Title of Invention	A POWER SPLIT ELECTRICALLY VARIABLE TRANSMISSION WITH DIFFERENTIAL GEARING WITHOUT TRANSMITTING ALL POWER THROUGH VARIABLE ELEMENTS
Abstract	A vehicle transmission includes a differential gear set having five coaxial gear elements and an output member. Two of the gear elements are controllable via torque transmitting mechanisms such as electric motors to establish a plurality of speed ratios between the input shaft and the output shaft. Two of the other gear elements are selectively operatively connectable to an output shaft via a gear arrangement that allows for a plurality of speed ratios between the gear elements and the output shaft. Additional torque transmitting mechanisms such as clutches are selectively engageable to provide continuously variable speed ranges between the input shaft and the output shaft, fixed gear ratios and an electric drive mode. The various speed ratios enable a plurality of compound split operating modes as well as an input split mode.

Title of Invention

A POWER SPLIT ELECTRICALLY VARIABLE TRANSMISSION WITH DIFFERENTIAL GEARING WITHOUT TRANSMITTING ALL POWER THROUGH VARIABLE ELEMENTS

Abstract

A vehicle transmission includes a differential gear set having five coaxial gear elements and an output member. Two of the gear elements are controllable via torque transmitting mechanisms such as electric motors to establish a plurality of speed ratios between the input shaft and the output shaft. Two of the other gear elements are selectively operatively connectable to an output shaft via a gear arrangement that allows for a plurality of speed ratios between the gear elements and the output shaft. Additional torque transmitting mechanisms such as clutches are selectively engageable to provide continuously variable speed ranges between the input shaft and the output shaft, fixed gear ratios and an electric drive mode. The various speed ratios enable a plurality of compound split operating modes as well as an input split mode.

Full Text	ELECTRICALLY VARIABLE TRANSMISSION WITH INPUT SPLIT MODE AND COMPOUND SPLIT MODES TECHNICAL FIELD [0001] The present invention relates to vehicle transmissions having a differential gear set and selectively engageable torque transmitting mechanisms including two electric motor-generators to provide continuously variable speed ranges, fixed gear ratios and an electric drive mode. BACKGROUND OF THE INENTION [0002] A vehicle transmission can deliver mechanical power from an engine to the remainder of a drive system, typically fixed gearing, axles, and wheels. A transmission allows some freedom in engine operation, usually through alternate selection of five or six different drive ratios, a neutral selection that allows the engine to operate accessories with the vehicle stationary and reverse. Transmission gear selection typically allows power from the engine to be delivered to the rest of the drive system with a ratio of torque multiplication and speed reduction and with a ratio of torque reduction and speed multiplication known as overdrive. [0003] An electric generator can transform mechanical power from the engine into electrical power, and an electric motor can transform that electric power back into mechanical power at different torques and speeds for the remainder of the vehicle drive system. This arrangement allows a continuous variation in the ratio of torque and speed between the engine and the remainder of the drive system, within the limits of the electric machinery. An electric storage battery used as a source of power for propulsion may be added to this arrangement, forming a series hybrid electric drive system. 10004] The series hybrid system allows the engine to operate relatively independently of the torque, speed, and power to propel a vehicle, so as to be controlled for improved emissions and efficiency. This system also allows the electric machine attached to the engine to function as a motor to start the engine and allows the electric machine attached to the remainder of the drive train to act as a generator, recovering energy into the battery by regenerative braking. However, a series electric drive requires that the electrical machinery be sufficiently sized to transform all engine power from mechanical to electrical form and from electrical to mechanical form, and useful power is lost in this double conversion. \|0005] A power split transmission can use what is commonly understood to be "differential gearing" to achieve a continuously variable torque and speed ratio between input and output without sending all power through the variable elements. One form of differential gearing may constitute a planetary gear set. In fact, planetary gearing is usually the preferred embodiment employed in differentially geared inventions, with the advantage of compactness and different torque and speed ratios among all members of the planetary gear set. However, it is possible to construct this invention without planetary gears, as by using bevel differential gears or other differential gears. [0006] A simple electrically variable transmission can use differential gearing to split power from the engine into two power paths to the wheels of the vehicle; an electro- mechanical path through a pair of electric machines or motor-generators and an all- mechanical parallel path that is fixed ratio or alternatively selectable. Electrically variable transmissions may form input-power-split, compound-power-split, or output-power-split configurations. [0007] An electrically variable transmission in a vehicle can simply transmit mechanical power. To do so, the electric power produced by one motor-generator balances the electrical losses and the electric power consumed by the other motor- generator. A hybrid electrically variable transmission system in a vehicle includes an electrical storage battery, so the electric power generated by one motor-generator can be greater than or less than the electric power consumed by the other. Electric power from the battery can sometimes allow both motor-generators to act as motors, especially to assist the engine with vehicle acceleration. Both motors can sometimes act as generators to recharge the battery, especially in regenerative vehicle braking. Electric power from the battery also allows engine starting with the transmission system. [0008] One of the most successful substitutes for the series hybrid transmission is the variable, two-mode, input-split, parallel-hybrid electric transmission. Such a transmission utilizes an input means to receive power from the vehicle engine and a power output member to deliver power to drive the vehicle. First and second motor- generators are connected to an energy storage device, such as a battery, so that the energy storage device can accept power from and supply power to the first and second motor- generators. A control means regulates power flow among the energy storage devices and the motor-generators as well as between the first and second motor-generators. [0009] Operation in a first or second mode may be selectively achieved by using clutches. In one mode, the output speed of the transmission is directly proportional to the speed of one motor-generator, and in the second mode the output speed of the transmission increases along with the speed of the other motor-generator. [0010] In some embodiments of the variable, two-mode, input-split, parallel- hybrid electric transmission a planetary gear set is selectively employed for torque multiplication. In addition, some embodiments may utilize three torque transmitting mechanisms—two to select the operational mode desired of the transmission and the third selectively to disconnect the transmission from the engine. [0011] As those skilled in the art will appreciate, a transmission system using a power split arrangement may receive power from two sources. However, the prior art does not include any practical gear schemes with an input-split operating mode and more than two compound split operating modes. The prior art document US6558283 discloses a transmission for motor vehicles, comprising two planetary trains; an input shaft introducing a torque of an internal combustion engine and coupled to one of said planetary trains; an output shaft coupled to said one planetary train; two electrical machines disposed in operative connection with said one planetary trains; said electrical machines being coupled neither to said input shaft nor to said output shaft and being variable independently of one another, each of said two electrical machines being each coupled to a respective one of said two planetary trains, each of said planetary trains being coupled to a separate gear shaft disposed in operative connection with said output shaft. The prior art document US7101298 discloses a two-mode compound split hybrid electro-mechanical transmission, comprising; first and second motor/generators; first, second and third planetary gear sets, each planetary gear set utilizing first, second and third gear members; said first and second motor/generators being coaxially aligned with each other and with said three planetary gear sets; at least one of said gear members in said first or second planetary gear set being connected to said first motor/generator; at least one of said gear members in said third planetary gear set being connected to said second motor/ generator; a first torque-transmitting mechanism selectively connecting one of said gear members of said third planetary gear set with ground; a second torque-transmitting mechanism selectively connecting one of said gear members associated with each of said first, second and third planetary gear sets to each other and to said output member; a third torque-transmitting mechanism selectively connecting one of said gear members of said second planetary set with ground; a fourth torque-transmitting mechanism selectively connecting one of said gear members with another of said gear members; a fifth torque-transmitting mechanism selectively connecting one of said gear members of said second planetary gear set with one of said gear members of said third planetary gear set; a first interconnecting member continuously connecting one of said gear members of said first planetary gear set with one of said gear members of said second planetary gear set; and a second interconnecting member continuously connecting another one of said gear members of said first planetary gear set with another one of said gear members of said second planetary gear set. The prior art document US7264071 discloses a hybrid powertrain comprising: an engine; a first motor/generator; a second motor/generator; a transmission output; at least two planetary gearsets selectively interconnecting said engine, said first motor/generator, and said second motor/generator to supply power to said transmission output, each of said gearsets having a plurality of gear elements; and a torque-transmitting mechanism selectively connective between said second motor/generator and a stationary member of said transmission to prevent rotation thereof and eliminate electrical power generation thereby, said torque transmitting mechanism being directly connected to said stationary member and said second motor generator, and continuously connected to at least one of said plurality of gear elements of each of a pair said at least two planetary gearsets. Objects of the Invention Therefore, it is an object of the invention to propose 'a power split electrically variable transmission with differential gearing without transmitting all power through variable elements which is capable of achieving a continuously variable torque and speed ratio between input and output. Another object of the invention is to propose "a power split electrically variable transmission with differential gearing without transmitting all power through variable elements" which can use differential gearing to split power from the engine into two power paths to the wheels of the vehicle, one being electro mechanical path through a pair of electric machines and the other being an all mechanical parallel path that is fixed ratio. A further object of the invention is to propose 'a power split electrically variable transmission with differential gearing without transmitting all power through variable elements', which is capable of providing operation in fixed gear ratio allowing the transmission to function without using the electric motor- generators to carry power from input to output. A still further object of the invention is to propose 'a power split electrically variable transmission with differential gearing without transmitting all power through variable elements', which allows the motor-generators to be used solely to convert battery power to output power or to convert power from the output into battery power at their full, combined capacity. SUMMARY OF THE INVENTION [0012] The present invention combines the use of an input-split mode with any number of compound-split modes as provided by the transmission gearing. It also provides for operation in fixed gear ratios, to allow the transmission to function without using the electric motor-generators to carry power from input to output. This fixed gear operation allows the transmission to operate even if one or both of the motor-generators are disabled; it allows the transmission to be designed to carry more power without enlarging the capacity of the motor-generators; it allows the motor-generators to be used solely to convert battery power to output power or to convert power from the output into battery power at their full, combined capacity. [0013] The mechanism consists of a compound planetary gear set attached to: the input, two electric motor-generators, and two selectable mechanical power paths to the output. The compound planetary gear set is interconnected to provide two independent speed variables, such as the input speed and a speed ratio through the gear set. The input, motor-generators, and output elements are attached to the compound planetary gear set such that their speeds may all be different from one another. Overall the speed of any element may be defined by a linear algebraic combination of the speeds of any two other elements. [0014] Thus, the operation of a single mechanical power path from the compound planetary gear set to the output results in a continuously-variable speed ratio range for the transmission, which may be controlled by the action of the motor-generators. [0015\| The simultaneous operation of two mechanical power paths from the compound planetary gear set to the output results in a mechanical speed ratio. There is, further, at least one selectable connection between at least one of the electric motor- generators and the output. These selectable connections may be used to provide a low, launch range and a reverse launch range using an input power split. A lockup clutch may be provided to selectively operate the compound planetary gear set in direct drive, so that additional fixed gear ratios may be selected. [0016] A vehicle transmission is.provided. The transmission includes a differential gear set having first, second, third, fourth, and fifth gear elements operatively interconnected with one another. An input shaft is operatively connected to the first gear element. A first selectively engageable torque transmitting mechanism is mounted to a stationary member and is operatively connected to the second gear element. A second selectively engageable torque transmitting mechanism is mounted to the stationary member and is operatively connected to the third gear element. A first output means is operatively connected to the fourth gear element, and a second output means is operatively connected to the fifth gear element. Furthermore, at least one of the second or third gear elements may be operatively connected to an output member, and at least one of said fourth or fifth gear element may be operatively connected to the output by more than one selectively engageable torque transmitting mechanism. [0017] The transmission of the invention may operate with fixed ratios, or may be employed with motor-generators as the first and second torque transmitting mechanisms to provide a large number of ratio ranges as a continuously variable transmission. Other torque transmitting mechanisms or clutches are selectively engageable to operatively connect various components of the transmission to provide continuously variable speed ranges, fixed gear ratios and electric drive. The gear set is configured such that the rotational speeds of two of the gear elements may be independently established and determine the rotational speeds of the other three gear elements. [0018] The power required from the motor-generators in continuously variable operation is kept to a small fraction of power through the transmission while the ratio spread can be wide. The overall capacity or "corner power" of the motor-generators can also be kept as low as practical differential gearing will allow. Since electric motors are relatively expensive and inefficient as compared with gearing, limiting their size will help make the transmission relatively inexpensive and efficient. The input-split mode of operation prevents the counter flow of power or power loop that would be formed at launch with a compound-power-split operating range, easing the requirements for the electric motors. [0019] The above features and other features and advantages of the present invention are readily apparent from the following detailed description of the best modes for carrying out the invention when taken in connection with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS [00201 FIGURE 1 is a schematic illustration of a vehicle transmission including a differential gear set according to the invention; and [0021] FIGURE 2 is a chart depicting some of the operating characteristics of the vehicle transmission shown in Figure 1. DESCRIPTION OF THE PREFERRED EMBODIMENTS [0022] The invention described herein is related to U.S Application S.N. 10/819,399 filed April 7, 2004, entitled "Compound Differential Dual Power Path Transmission" which is commonly assigned with this application to General Motors, and which is hereby incorporated by reference in its entirety. [0023] Referring to Figure 1, a vehicular transmission 10 is schematically depicted. The transmission 10 includes a compound differential, Ravineaux gear set 14. The gear set 14 includes a first ring gear member 18, a second ring gear member 22, a planet carrier assembly member 26 including a first set of pinion gears 30 and a second set of pinion gears 34 rotatably mounted thereto, a first sun gear member 38, and a second sun gear member 42. The first sun gear member 38 is meshingly engaged with the first set of pinion gears 30. The second sun gear member 42 is meshingly engaged with the second set of pinion gears 34. The first ring gear member 18 is meshingly engaged with the first set of pinion gears 30, and the second ring gear member 22 is meshingly engaged with the second set of pinion gears 34. The first set of pinion gears 30 is meshingly engaged with the second set of pinion gears 34. [0024] The differential gear set 14 has five members 18, 22, 26, 38, 42 on a common axis A, and is configured so that the speeds of any two of the gear members are capable of being established independently of one another, and the speeds of the other three gear members are dependent on the speeds established for the two gear members. Thus, for example, the rotational speeds of the planetary carrier 26 and the first sun gear 38 may be established independently, and the rotational speeds of the second sun gear 42, the first ring gear 18, and the second ring gear 22 are determined by the speeds of the planetary carrier 26 and the first sun gear 38. Similarly, the rotational speeds of the planetary carrier 26 and the second sun gear 42 may be established independently, and the rotational speeds of the first sun gear 38, the first ring gear 18, and the second ring gear 22 are determined by the speeds of the planetary carrier 26 and the second sun gear 42. The transmission 10 further comprises an input shaft 46. [0025] A first torque transmitting mechanism 50 operatively interconnects the second sun gear member 42 and a stationary member such as the transmission housing 54. A second torque transmitting mechanism 58 operatively interconnects the first sun gear member 38 and the transmission housing 54. The first and second torque transmitting mechanisms 50, 58 may be friction brakes, electric motor-generators, combinations thereof etc., within the scope of the claimed invention. In a preferred embodiment, the torque transmitting mechanisms 50, 58 are electric motors each having a stator 62 rigidly mounted to the housing 54 and a rotor 66 rigidly affixed to one of the sun gears 38, 42 for rotation therewith. The rotor 66 of the first torque transmitting mechanism 50 is affixed to sun gear 42 via a sleeve 70 around the input shaft 46. Output Members [0026[ The transmission 10 includes two output members, namely, a first countershaft 78 and a second countershaft 80, that are operatively connected to the gear set 14 and that together provide three selectable power paths by which power may flow to an output shaft 76. Four gear members 82, 84, 86 and 88 are connected to the first countershaft 78 for rotation therewith. Four gear members 90, 92, 94 and 96 are connected to the second countershaft 80 for rotation therewith. Gear members 102, 106 and 110 are rotatably supported by a central shaft 77. Gear member 114 is rotatably supported by the output shaft 76. The gear members 102, 106, 110 and 114 are meshingly engaged with gear members 82, 84, 86 and 88, respectively. The gear members 102, 106, 110 and 114 are meshingly engaged with gear members 90, 92, 94 and 96, respectively. Clutches [0027] As illustrated in the embodiment shown in Figure 1, multiple torque transmitting mechanisms, such as clutches, are configured to selectively establish a drive connection between various components of the transmission 10. A first clutch 72 is selectively engageable to operatively connect an input shaft 46 to the planet carrier assembly member 26. [0028] A second clutch 74 is selectively engageable to operatively connect the first ring gear member 18 to the second ring gear 22, through a central shaft 77. A sleeve 75 surrounds the central shaft 77. [0029] A third clutch 100 is selectively engageable to operatively connect the first sun gear member 38 (and rotor 66 of the second torque transmitting mechanism 58) to a gear member 102. Gear member 102 is rotatably supported by the central shaft 77: Gear member 102 is connected to countershafts 78 and 80 through meshing engagements with gear members 82 and 90, respectively. [0030] A fourth clutch 104 is selectively engageable to operatively connect the first ring gear member 18 to a gear member 106. Gear member 106 is rotatably supported by the central shaft 77. Gear member 106 is connected to countershafts 78 and 80 through meshing engagements with gear members 84 and 92, respectively. [0031] A fifth clutch 108 is selectively engageable to operatively connect the first ring gear member 18 to a gear member 110. Gear member 110 is rotatably supported by the central shaft 77. Gear member 110 is connected to countershafts 78 and 80 through meshing engagements with gear members 86 and 94, respectively. [0032] A sixth clutch 112 is selectively engageable to operatively connect the second ring gear 22, through the central shaft 77, to a gear member 114 which is connected to the output shaft 76. Modes of Operation \|0033] As shown in Figure 2 and described below, the torque-transmitting mechanisms and clutches shown in Figure 1 are selectively engageable to provide multiple continuously variable speed ranges (V1-V4), fixed gear ratios (F1-F7) and an electric drive mode (El). Fixed Speed Ratios [0034] A first forward speed ratio Fl is established with the engagement of first clutch 72, second clutch 74 and third clutch 100. The first clutch 72 operatively connects the input shaft 46 to the planet carrier assembly member 26. The second clutch 74 operatively connects the first ring gear member 18 to the second ring gear member 22. The third clutch 100 operatively connects the first sun gear member 38 to two output members, the first countershaft 78 and the second countershaft 80. [0035] A second forward speed ratio F2 is established with the engagement of first clutch 72, third clutch 100 and fourth clutch 104. The first clutch 72 operatively connects the input shaft 46 to the planet carrier assembly member 26. The third clutch 100 operatively connects the first sun gear member 38 to two output members, the first countershaft 78 and the second countershaft 80. The fourth clutch 104 operatively connects the first ring gear member 18 to one of the two output members, the first countershaft 78 and the second countershaft 80. [0036] A third forward speed ratio F3 is established with the engagement of first clutch 72, second clutch 74 and fourth clutch 104. The first clutch 72 operatively connects the input shaft 46 to the planet carrier assembly member 26. The second clutch 74 operatively connects the first ring gear member 18 to the second ring gear member 22. The fourth clutch 104 operatively connects the first ring gear member 18 to two output members, the first countershaft 78 and the second countershaft 80. (0037] A fourth forward speed ratio F4 is established with the engagement of first clutch 72, fourth clutch 104 and sixth clutch 112. The first clutch 72 operatively connects the input shaft 46 to the planet carrier assembly member 26. The fourth clutch 104 operatively connects the first ring gear member 18 to two output members, the first countershaft 78 and the second countershaft 80. The sixth clutch 112 operatively connects the second ring gear 22 to the output shaft 76. [0038] A fifth forward speed ratio F5 is established with the engagement of first clutch 72, second clutch 74 and sixth clutch 112. The first clutch 72 operatively connects the input shaft 46 to the planet carrier assembly member 26. The second clutch 74 operatively connects the first ring gear member 18 to-the second ring gear member 22. The sixth clutch 112"operatively connects the second ring gear 22 to the output shaft 76. [0039] A sixth forward speed ratio F6 is established with the engagement of first clutch 72, fifth clutch 108 and sixth clutch 112. The first clutch 72 operatively connects the input shaft 46 to the planet carrier assembly member 26. The fifth clutch 108 operatively connects the first ring gear member 18 to two output members, the first countershaft 78 and the second countershaft 80. The sixth clutch 112 operatively connects the second ring gear 22 to the output shaft 76. [0040] A seventh forward speed ratio F7 is established with the engagement of first clutch 72, second clutch 74 and fifth clutch 108. The first clutch 72 operatively connects the input shaft 46 to the planet carrier assembly member 26. The second clutch 74 operatively connects the first ring gear member 18 to the second ring gear member 22. The fifth clutch 108 operatively connects the first ring gear member 18 to two output members, the first countershaft 78 and the second countershaft 80. Electric Drive Mode [0041] An electric drive mode El is established with the engagement of the third clutch 100. The third clutch 100 operatively connects the first sun gear member 38 to two output members, the first countershaft 78 and the second countershaft 80. The input shaft 46 is not connected to the rest of the transmission 10 i.e. the engine is disconnected from the transmission 10. Power is provided by the torque transmitting mechanisms 50, 58 functioning as electric motors. Continuously Variable Range Modes [0042] When the torque transmitting mechanisms 50, 58 are motors or include motors, the transmission 10 can be operated as a CVT, by absorbing power with one motor and using it in the other motor. The transmission 10 of Figure 1 is capable of multiple continuously variable ranges or modes. [0043] A first variable speed range VI is established with the engagement of first clutch 72 and third clutch 100. The first clutch 72 operatively connects the input shaft 46 to the planet carrier assembly member 26. The third clutch 100 operatively connects the first sun gear member 38 to two output members, the first countershaft 78 and the second countershaft 80. [0044] A second variable speed range V2 is established with the engagement of first clutch 72 and fourth clutch 104. The first clutch 72 operatively connects the input shaft 46 to the planet carrier assembly member 26. The fourth clutch 104 operatively connects the first ring gear member 18 to two output members, the first countershaft 78 and the second countershaft 80. [0045] A third variable speed range V3 is established with the engagement of first clutch 72 and sixth clutch 112. The first clutch 72 operatively connects the input shaft 46 to the planet carrier assembly member 26. The sixth clutch 112 operatively connects the second ring gear 22 to the output shaft 76. [0046] A fourth variable speed range V4 is established with the engagement of first clutch 72 and fifth clutch 108. The first clutch 72 operatively connects the input shaft 46 to the planet carrier assembly member 26. The fifth clutch 108 operatively connects the first ring gear member 18 to two output member the first countershaft 78 and the second countershaft 80. [0047] The continuously variable ranges are input power split when third clutch 100 is engaged i.e. variable range VI is input split. Modes V2, V3 and V4 are compound split. The input-power-split configuration has special advantage for vehicle launching, because one of the electric motor-generators is at zero speed with the output at zero speed; no power loop is present during launch. A compound power split configuration has special advantage for operation with finite speed ratios because they have a definite and relatively broad range where transmission power is fed forward and no power loop is present in this range. [0048] Each CVT range or mode is covered as the speed of one torque transmitting mechanism is decreasing and the speed of the other is increasing. Thus, each CVT mode corresponds to a shift between the fixed speed ratios of the transmission as described above. Transitions between successive modes or ranges occur as the countershaft gearing is selectively engaged and disengaged, and correspond to fixed speed ratios of the transmission described above. [0049] Thus, the same transmission gearing, compound planetary gearing, and dual countershaft gearing can be useful in both stepped ratio and continuously variable transmissions, and, in fact, a transmission can be constructed to operate effectively in both ways. The transmission 10 can be operated practically as a stepped ratio transmission, CVT, or combination of the two. [0050] It should be noted that the first countershaft 78 and the second countershaft 80 may be operatively connected to the output shaft 76 simultaneously so that both countershafts transmit power to the output shaft. [0051] The torque transmitting mechanisms 50, 58 selectively control the rotational speed of the sun gears 42, 38. As described above, different speed ratios between the input shaft 46 and the two countershafts 78 and 80 are established through selective engagement of the torque transmitting mechanisms 50, 58 and clutches 72, 74, 100, 104, 112, 108 and corresponding control of sun gear speed. [0052] While countershafts 78, 80 are employed together as a single operative output means and the output shaft is employed directly as another output means in a preferred embodiment, those skilled in the art will recognize a variety of different output member configurations that may be employed within the scope of the invention to form dual power paths from the gear set 14 to an output shaft 76. For example, members of a second planetary gear set may be operatively connected to the first and second ring gears 18 and 22 and selectively engageable via clutches to an output shaft. Moreover, those skilled in the art will recognize that it may be desirable to add additional gears to the countershafts and the output shaft to increase the number of speed ratios available between the countershafts and the output shaft. [0053] In a preferred embodiment, the transmission 10 also includes an energy storage device such as a battery 136 operatively connected via conductive wires 134 to the motors of torque transmitting mechanisms 50, 58 to receive power from them and to supply power to them. A controller 132 is operatively connected to the battery and the motors to regulate the flow of power among them. Thus, a hybrid transmission is formed. If torque transmitting mechanisms 50, 58 are electric generators, they can apply torque indefinitely even' if their shafts are rotating. Thus, the shifts described above can be transformed into compound power split operating ranges. That is, the braking torque and speed applied by one of the torque transmitting mechanisms to spin the gear set element corresponding to one of the countershafts slower than the input can be transformed into power used by the other torque transmitting mechanism to spin the element corresponding to the other countershaft faster than the input. [0054] While the best modes for carrying out the invention have been described in detail, those familiar with the art to which this invention relates will recognize various alternative designs and embodiments for practicing the invention within the scope of the appended claims. WE CLAIM: 1. A power split electrically variable transmission with differential gearing without transmitting all power through variable elements, the said vehicle transmission comprising; a stationary member (54); a differential gear set (14) having first (18), second (22), third (26), fourth (38), and fifth (42) coaxial gear elements operatively interconnected with one another; an input shaft (46); an output shaft (76); Characterized in that, first (72), second (74), third (100), fourth (104), fifth (112) and sixth (108) torque-transmitting mechanisms selectively engageable to operatively connect one of said gear elements with said stationary member or with said output shaft; wherein the first (72) and second (74) of said torque-transmitting mechanisms are capable of operatively exchanging power with one another; wherein said torque-transmitting mechanisms are configured to produce an input-split operating mode (V1), a first compound-split operating mode (V2), a second compound-split operating mode (V3) a third compound-split operating mode (V4) of the transmission (10); wherein said third torque (100) transmitting mechanism is selectively engageable to operatively connect one of said gear elements to the output shaft (76) to form an input-split operating mode (V1), wherein said one of said gear element is continuously connected to said first or second troque transmitting mechanism such that the rotational speed of said one of said gear elements is proportional to the rotational speed of said first or second torque transmitting mechanism; wherein the differential gear set (14) is configured such that the rotational speeds of two of the gear elements (26,38) may be independently established and determine the rotational speeds of the three gear elements (42,18,22). the fourth torque transmitting mechanism (104) is selectively engageable to operatively connect the fourth gear element (38) to the output shaft (76) to form the first compound-split operating mode (V2); the fifth torque transmitting mechanism (112) is selectively engageable to operatively connect the fifth gear elements (42) to the said output shaft (76) to form the second compound-split operating mode (V3) and the sixth torque transmitting mechanism (108) is selectively engageable to operatively connect said fourth gear element (38) to the output shaft (76) to form the third compound-split operating mode (V4); 2. A vehicle transmission (10) comprising; a stationary member (54); a differential gear set (14) having first (18), second (22), third (26), fourth (38), and fifth (42) coaxial gear elements operatively interconnected with one another; an input shaft (46); an output shaft (76); first (72), second (74), third (100), fourth (104), fifth (112) and sixth (108) torque-transmitting mechanisms selectively engageable to operatively connect one of said gear elements with said stationary member or with said output shaft; wherein the first (72) and second (74) of said torque-transmitting mechanisms are capable of operatively exchanging power with one another; operation of said torque-transmitting mechanisms results in an input-split operating mode (V1), a first compound-split operating mode (V2), a second compound- split operating mode (V3) and a third compound-split operating mode (V4) of the transmission (10); the input shaft (46) is operatively connected to the first gear element (18); the first torque-transmitting mechanism (72) is mounted to the stationary member (54) and is selectively engageable to operativeiy connect to the second gear element (22); the second torque transmitting mechanism (74) is mounted to the stationary member (54) and is selectively engageable to operatively connect to the third gear element (26); the third torque transmitting mechanism (100) is selectively engageable to operatively connect one of said gear elements to the output shaft (76) to form an input- split operating mode, wherein said one of said gear elements is operativeiy connected to said first or second torque transmitting mechanism; the fourth torque transmitting mechanism (104) is selectively engageable to operatively connect the fourth gear element (22) to the output shaft (76) to form a first compound- split operating mode (V2); the fifth torque transmitting mechanism (112) is selectively engageable to operatively connect the fifth gear elements (22) to said output shaft (76) to form the second compound-split operating mode (V3); and the sixth torque transmitting mechanism (108) is selectively engageable to operatively connect said fourth gear element (18) to the output shaft (76) to form the third compound-split operating mode (V4). 3. The transmission as claimed in claim 1, wherein the output member includes at least one countershaft (78, 80). 4. The transmission as claimed in claim 2, optionally comprising a seventh torque transmitting mechanism (50) selectively engageable to operatively connect one gear element to another gear element in such a way as to cause all of the gear elements of the gear set to rotate at substantially the same speed. 5. The transmission as claimed in claim 4, optionally comprising an eighth torque transmitting mechanism (58) selectively disengageable to operatively disconnect the input shaft (46) from the first gear element (38). 6. The transmission as claimed in claim 1, wherein the speed ratio between the input shaft (46) and output shaft (76) is selectively variable by selectively engaging the first (72) and second (74) torque transmitting mechanisms to control the rotational speed of the second (22) and third (26) gear elements, respectively. 7. The transmission as claimed in claim 4: wherein a first speed ratio (F2) is established between the input shaft (46) and the output shaft (76), when the third (100) and seventh (54) torque transmitting mechanisms are selectively engaged; wherein a second speed ratio (F2) is established between the input shaft and the output shaft, when third (100) and fourth (104) torque transmitting mechanisms are selectively engaged; wherein a third speed ratio (F3) is established between the input shaft (46) and the output shaft (76), when the fourth (104) and seventh (54) torque transmitting mechanisms are selectively engaged; wherein a fourth speed ratio is established between the input shaft (46) and the out shaft (76), when the fourth (104) and fifth (112) torque transmitting mechanisms are selectively engaged; wherein a fifth speed ratio (F5) is established between the input shaft (46) and the output shaft (76), when the fifth (112) and seventh (54) torque transmitting mechanisms are selectively engaged;, wherein a sixth speed ratio (F6) is established between the input shaft and the output shaft, when the fifth (112) and sixth (108) torque transmitting mechanisms are selectively engaged; and wherein a seventh speed ration (F7) is established between the input shaft (46) and the output shaft (76), when the sixth (108) and seventh (54) torque transmitting mechanisms are selectively engaged. 8. The transmission as claimed in claim 1, wherein the differential gear set (14) includes a planet carrier (26), a first sun gear (38), a second sun gear (42), a first ring gear (18) and a second ring gear (22); wherein the planet carrier (26) is equipped with a first set of planet pinion gears (30) which mesh with the first sun gear (38) and first ring rear (18) and a second set of planet pinion gears (30) which mesh with the second sun gear (42) and second ring gear (42); and wherein the first set of planet pinion gears (30) meshes with the second set of planet pinion gears (34). 9. The transmission as claimed in claim 8, wherein the first gear element is the planet carrier (26), the second gear element is one of the sun gears (38/42), the third gear element is the other of the sun gears (38/42), the fourth gear element is one of the ring gears (18/22);and the fifth gear element is the other of the ring gears (18/22). 10. The transmission as claimed in claim 2, wherein the first torque transmitting mechanism (50) and the second torque transmitting mechanism (58) are electric motor- generators. 11. The transmission as claimed in claim 1, optionally comprising an energy storage device for accepting power from, and supplying power to, the first and second torque transmitting mechanisms (50,58); and a controller for regulating power flow among the energy storage device and the first and second torque transmitting mechanisms (50,58). 12. The transmission as claimed in claim 11, wherein the output (76) may be driven by power from the energy storage device alone, without power from the input (46), through the action of at least one of the first or second torque transmitting mechanisms (50,58). ABSTRACT A POWER SPLIT ELECTRICALLY VARIABLE TRANSMISSION WITH DIFFERENTIAL GEARING WITHOUT TRANSMITTING ALL POWER THROUGH VARIABLE ELEMENTS. A vehicle transmission includes a differential gear set having five coaxial gear elements and an output member. Two of the gear elements are controllable via torque transmitting mechanisms such as electric motors to establish a plurality of speed ratios between the input shaft and the output shaft. Two of the other gear elements are selectively operatively connectable to an output shaft via a gear arrangement that allows for a plurality of speed ratios between the gear elements and the output shaft. Additional torque transmitting mechanisms such as clutches are selectively engageable to provide continuously variable speed ranges between the input shaft and the output shaft, fixed gear ratios and an electric drive mode. The various speed ratios enable a plurality of compound split operating modes as well as an input split mode.

Full Text

ELECTRICALLY VARIABLE TRANSMISSION WITH INPUT SPLIT MODE AND
COMPOUND SPLIT MODES
TECHNICAL FIELD
[0001] The present invention relates to vehicle transmissions having a differential
gear set and selectively engageable torque transmitting mechanisms including two
electric motor-generators to provide continuously variable speed ranges, fixed gear ratios
and an electric drive mode.
BACKGROUND OF THE INENTION
[0002] A vehicle transmission can deliver mechanical power from an engine to
the remainder of a drive system, typically fixed gearing, axles, and wheels. A transmission allows some freedom in engine operation, usually through alternate
selection of five or six different drive ratios, a neutral selection that allows the engine to
operate accessories with the vehicle stationary and reverse. Transmission gear selection
typically allows power from the engine to be delivered to the rest of the drive system with
a ratio of torque multiplication and speed reduction and with a ratio of torque reduction
and speed multiplication known as overdrive.
[0003] An electric generator can transform mechanical power from the engine
into electrical power, and an electric motor can transform that electric power back into
mechanical power at different torques and speeds for the remainder of the vehicle drive
system. This arrangement allows a continuous variation in the ratio of torque and speed
between the engine and the remainder of the drive system, within the limits of the electric
machinery. An electric storage battery used as a source of power for propulsion may be
added to this arrangement, forming a series hybrid electric drive system.

10004] The series hybrid system allows the engine to operate relatively

independently of the torque, speed, and power to propel a vehicle, so as to be controlled

for improved emissions and efficiency. This system also allows the electric machine
attached to the engine to function as a motor to start the engine and allows the electric
machine attached to the remainder of the drive train to act as a generator, recovering
energy into the battery by regenerative braking. However, a series electric drive requires
that the electrical machinery be sufficiently sized to transform all engine power from
mechanical to electrical form and from electrical to mechanical form, and useful power is
lost in this double conversion.
|0005] A power split transmission can use what is commonly understood to be
"differential gearing" to achieve a continuously variable torque and speed ratio between input and output without sending all power through the variable elements. One form of
differential gearing may constitute a planetary gear set. In fact, planetary gearing is
usually the preferred embodiment employed in differentially geared inventions, with the
advantage of compactness and different torque and speed ratios among all members of
the planetary gear set. However, it is possible to construct this invention without
planetary gears, as by using bevel differential gears or other differential gears.
[0006] A simple electrically variable transmission can use differential gearing to
split power from the engine into two power paths to the wheels of the vehicle; an electro-
mechanical path through a pair of electric machines or motor-generators and an all-
mechanical parallel path that is fixed ratio or alternatively selectable. Electrically variable
transmissions may form input-power-split, compound-power-split, or output-power-split
configurations.
[0007] An electrically variable transmission in a vehicle can simply transmit
mechanical power. To do so, the electric power produced by one motor-generator
balances the electrical losses and the electric power consumed by the other motor-
generator. A hybrid electrically variable transmission system in a vehicle includes an
electrical storage battery, so the electric power generated by one motor-generator can be
greater than or less than the electric power consumed by the other. Electric power from

the battery can sometimes allow both motor-generators to act as motors, especially to
assist the engine with vehicle acceleration. Both motors can sometimes act as generators
to recharge the battery, especially in regenerative vehicle braking. Electric power from
the battery also allows engine starting with the transmission system.
[0008] One of the most successful substitutes for the series hybrid transmission is
the variable, two-mode, input-split, parallel-hybrid electric transmission. Such a
transmission utilizes an input means to receive power from the vehicle engine and a
power output member to deliver power to drive the vehicle. First and second motor-
generators are connected to an energy storage device, such as a battery, so that the energy
storage device can accept power from and supply power to the first and second motor-
generators. A control means regulates power flow among the energy storage devices and
the motor-generators as well as between the first and second motor-generators.
[0009] Operation in a first or second mode may be selectively achieved by using
clutches. In one mode, the output speed of the transmission is directly proportional to the
speed of one motor-generator, and in the second mode the output speed of the
transmission increases along with the speed of the other motor-generator.
[0010] In some embodiments of the variable, two-mode, input-split, parallel-
hybrid electric transmission a planetary gear set is selectively employed for torque
multiplication. In addition, some embodiments may utilize three torque transmitting
mechanisms—two to select the operational mode desired of the transmission and the third
selectively to disconnect the transmission from the engine.
[0011] As those skilled in the art will appreciate, a transmission system using a
power split arrangement may receive power from two sources. However, the prior art
does not include any practical gear schemes with an input-split operating mode and more
than two compound split operating modes.

The prior art document US6558283 discloses a transmission for
motor vehicles, comprising two planetary trains; an input shaft introducing a
torque of an internal combustion engine and coupled to one of said planetary
trains; an output shaft coupled to said one planetary train; two electrical machines
disposed in operative connection with said one planetary trains; said electrical
machines being coupled neither to said input shaft nor to said output shaft and
being variable independently of one another, each of said two electrical machines
being each coupled to a respective one of said two planetary trains, each of said
planetary trains being coupled to a separate gear shaft disposed in operative
connection with said output shaft.
The prior art document US7101298 discloses a two-mode compound
split hybrid electro-mechanical transmission, comprising; first and second
motor/generators; first, second and third planetary gear sets, each planetary gear
set utilizing first, second and third gear members; said first and second
motor/generators being coaxially aligned with each other and with said three
planetary gear sets; at least one of said gear members in said first or second
planetary gear set being connected to said first motor/generator; at least one of
said gear members in said third planetary gear set being connected to said second
motor/ generator; a first torque-transmitting mechanism selectively connecting
one of said gear members of said third planetary gear set with ground; a second
torque-transmitting mechanism selectively connecting one of said gear members
associated with each of said first, second and third planetary gear sets to each
other and to said output member; a third torque-transmitting mechanism
selectively connecting one of said gear members of said second planetary set with
ground; a fourth torque-transmitting mechanism selectively connecting one of said
gear members with another of said gear members; a fifth torque-transmitting
mechanism selectively connecting one of said gear members of said second
planetary gear set with one of said gear members of said third planetary

gear set; a first interconnecting member continuously connecting one of said gear
members of said first planetary gear set with one of said gear members of said
second planetary gear set; and a second interconnecting member continuously
connecting another one of said gear members of said first planetary gear set with
another one of said gear members of said second planetary gear set.
The prior art document US7264071 discloses a hybrid powertrain
comprising: an engine; a first motor/generator; a second motor/generator; a
transmission output; at least two planetary gearsets selectively interconnecting
said engine, said first motor/generator, and said second motor/generator to supply
power to said transmission output, each of said gearsets having a plurality of gear
elements; and a torque-transmitting mechanism selectively connective between
said second motor/generator and a stationary member of said transmission to
prevent rotation thereof and eliminate electrical power generation thereby, said
torque transmitting mechanism being directly connected to said stationary member
and said second motor generator, and continuously connected to at least one of
said plurality of gear elements of each of a pair said at least two planetary
gearsets.
Objects of the Invention
Therefore, it is an object of the invention to propose 'a power split
electrically variable transmission with differential gearing without transmitting all
power through variable elements which is capable of achieving a continuously
variable torque and speed ratio between input and output.
Another object of the invention is to propose "a power split electrically variable
transmission with differential gearing without transmitting all power through
variable elements" which can use differential gearing to split power from the

engine into two power paths to the wheels of the vehicle, one being electro
mechanical path through a pair of electric machines and the other being an all
mechanical parallel path that is fixed ratio.
A further object of the invention is to propose 'a power split
electrically variable transmission with differential gearing without transmitting all
power through variable elements', which is capable of providing operation in fixed
gear ratio allowing the transmission to function without using the electric motor-
generators to carry power from input to output.
A still further object of the invention is to propose 'a power split
electrically variable transmission with differential gearing without transmitting all
power through variable elements', which allows the motor-generators to be used
solely to convert battery power to output power or to convert power from the
output into battery power at their full, combined capacity.

SUMMARY OF THE INVENTION
[0012] The present invention combines the use of an input-split mode with any
number of compound-split modes as provided by the transmission gearing. It also
provides for operation in fixed gear ratios, to allow the transmission to function without
using the electric motor-generators to carry power from input to output. This fixed gear
operation allows the transmission to operate even if one or both of the motor-generators
are disabled; it allows the transmission to be designed to carry more power without
enlarging the capacity of the motor-generators; it allows the motor-generators to be used
solely to convert battery power to output power or to convert power from the output into
battery power at their full, combined capacity.
[0013] The mechanism consists of a compound planetary gear set attached to: the
input, two electric motor-generators, and two selectable mechanical power paths to the
output. The compound planetary gear set is interconnected to provide two independent
speed variables, such as the input speed and a speed ratio through the gear set. The input,
motor-generators, and output elements are attached to the compound planetary gear set
such that their speeds may all be different from one another. Overall the speed of any
element may be defined by a linear algebraic combination of the speeds of any two other
elements.
[0014] Thus, the operation of a single mechanical power path from the compound
planetary gear set to the output results in a continuously-variable speed ratio range for the
transmission, which may be controlled by the action of the motor-generators.
[0015| The simultaneous operation of two mechanical power paths from the
compound planetary gear set to the output results in a mechanical speed ratio. There is,
further, at least one selectable connection between at least one of the electric motor-
generators and the output. These selectable connections may be used to provide a low,
launch range and a reverse launch range using an input power split. A lockup clutch may
be provided to selectively operate the compound planetary gear set in direct drive, so that
additional fixed gear ratios may be selected.

[0016] A vehicle transmission is.provided. The transmission includes a
differential gear set having first, second, third, fourth, and fifth gear elements operatively
interconnected with one another. An input shaft is operatively connected to the first gear
element. A first selectively engageable torque transmitting mechanism is mounted to a
stationary member and is operatively connected to the second gear element. A second
selectively engageable torque transmitting mechanism is mounted to the stationary
member and is operatively connected to the third gear element. A first output means is
operatively connected to the fourth gear element, and a second output means is
operatively connected to the fifth gear element. Furthermore, at least one of the second
or third gear elements may be operatively connected to an output member, and at least
one of said fourth or fifth gear element may be operatively connected to the output by
more than one selectively engageable torque transmitting mechanism.
[0017] The transmission of the invention may operate with fixed ratios, or may be
employed with motor-generators as the first and second torque transmitting mechanisms
to provide a large number of ratio ranges as a continuously variable transmission. Other
torque transmitting mechanisms or clutches are selectively engageable to operatively
connect various components of the transmission to provide continuously variable speed
ranges, fixed gear ratios and electric drive. The gear set is configured such that the
rotational speeds of two of the gear elements may be independently established and
determine the rotational speeds of the other three gear elements.
[0018] The power required from the motor-generators in continuously variable
operation is kept to a small fraction of power through the transmission while the ratio
spread can be wide. The overall capacity or "corner power" of the motor-generators can
also be kept as low as practical differential gearing will allow. Since electric motors are
relatively expensive and inefficient as compared with gearing, limiting their size will help
make the transmission relatively inexpensive and efficient. The input-split mode of
operation prevents the counter flow of power or power loop that would be formed at
launch with a compound-power-split operating range, easing the requirements for the
electric motors.

[0019] The above features and other features and advantages of the present
invention are readily apparent from the following detailed description of the best modes
for carrying out the invention when taken in connection with the accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[00201 FIGURE 1 is a schematic illustration of a vehicle transmission including a
differential gear set according to the invention; and
[0021] FIGURE 2 is a chart depicting some of the operating characteristics of the
vehicle transmission shown in Figure 1.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0022] The invention described herein is related to U.S Application S.N.
10/819,399 filed April 7, 2004, entitled "Compound Differential Dual Power Path
Transmission" which is commonly assigned with this application to General Motors, and
which is hereby incorporated by reference in its entirety.
[0023] Referring to Figure 1, a vehicular transmission 10 is schematically
depicted. The transmission 10 includes a compound differential, Ravineaux gear set 14.
The gear set 14 includes a first ring gear member 18, a second ring gear member 22, a
planet carrier assembly member 26 including a first set of pinion gears 30 and a second
set of pinion gears 34 rotatably mounted thereto, a first sun gear member 38, and a
second sun gear member 42. The first sun gear member 38 is meshingly engaged with
the first set of pinion gears 30. The second sun gear member 42 is meshingly engaged
with the second set of pinion gears 34. The first ring gear member 18 is meshingly
engaged with the first set of pinion gears 30, and the second ring gear member 22 is
meshingly engaged with the second set of pinion gears 34. The first set of pinion gears
30 is meshingly engaged with the second set of pinion gears 34.

[0024] The differential gear set 14 has five members 18, 22, 26, 38, 42 on a
common axis A, and is configured so that the speeds of any two of the gear members are
capable of being established independently of one another, and the speeds of the other
three gear members are dependent on the speeds established for the two gear members.
Thus, for example, the rotational speeds of the planetary carrier 26 and the first sun gear
38 may be established independently, and the rotational speeds of the second sun gear 42,
the first ring gear 18, and the second ring gear 22 are determined by the speeds of the
planetary carrier 26 and the first sun gear 38. Similarly, the rotational speeds of the
planetary carrier 26 and the second sun gear 42 may be established independently, and
the rotational speeds of the first sun gear 38, the first ring gear 18, and the second ring
gear 22 are determined by the speeds of the planetary carrier 26 and the second sun gear
42. The transmission 10 further comprises an input shaft 46.
[0025] A first torque transmitting mechanism 50 operatively interconnects the
second sun gear member 42 and a stationary member such as the transmission housing
54. A second torque transmitting mechanism 58 operatively interconnects the first sun
gear member 38 and the transmission housing 54. The first and second torque
transmitting mechanisms 50, 58 may be friction brakes, electric motor-generators,
combinations thereof etc., within the scope of the claimed invention. In a preferred
embodiment, the torque transmitting mechanisms 50, 58 are electric motors each having a
stator 62 rigidly mounted to the housing 54 and a rotor 66 rigidly affixed to one of the
sun gears 38, 42 for rotation therewith. The rotor 66 of the first torque transmitting
mechanism 50 is affixed to sun gear 42 via a sleeve 70 around the input shaft 46.
Output Members
[0026[ The transmission 10 includes two output members, namely, a first
countershaft 78 and a second countershaft 80, that are operatively connected to the gear
set 14 and that together provide three selectable power paths by which power may flow to
an output shaft 76. Four gear members 82, 84, 86 and 88 are connected to the first
countershaft 78 for rotation therewith. Four gear members 90, 92, 94 and 96 are
connected to the second countershaft 80 for rotation therewith. Gear members 102, 106

and 110 are rotatably supported by a central shaft 77. Gear member 114 is rotatably
supported by the output shaft 76. The gear members 102, 106, 110 and 114 are meshingly
engaged with gear members 82, 84, 86 and 88, respectively. The gear members 102, 106,
110 and 114 are meshingly engaged with gear members 90, 92, 94 and 96, respectively.
Clutches
[0027] As illustrated in the embodiment shown in Figure 1, multiple torque
transmitting mechanisms, such as clutches, are configured to selectively establish a drive
connection between various components of the transmission 10. A first clutch 72 is
selectively engageable to operatively connect an input shaft 46 to the planet carrier
assembly member 26.
[0028] A second clutch 74 is selectively engageable to operatively connect the
first ring gear member 18 to the second ring gear 22, through a central shaft 77. A sleeve
75 surrounds the central shaft 77.
[0029] A third clutch 100 is selectively engageable to operatively connect the first
sun gear member 38 (and rotor 66 of the second torque transmitting mechanism 58) to a
gear member 102. Gear member 102 is rotatably supported by the central shaft 77: Gear
member 102 is connected to countershafts 78 and 80 through meshing engagements with
gear members 82 and 90, respectively.
[0030] A fourth clutch 104 is selectively engageable to operatively connect the
first ring gear member 18 to a gear member 106. Gear member 106 is rotatably supported
by the central shaft 77. Gear member 106 is connected to countershafts 78 and 80 through
meshing engagements with gear members 84 and 92, respectively.
[0031] A fifth clutch 108 is selectively engageable to operatively connect the first
ring gear member 18 to a gear member 110. Gear member 110 is rotatably supported by
the central shaft 77. Gear member 110 is connected to countershafts 78 and 80 through
meshing engagements with gear members 86 and 94, respectively.
[0032] A sixth clutch 112 is selectively engageable to operatively connect the
second ring gear 22, through the central shaft 77, to a gear member 114 which is
connected to the output shaft 76.

Modes of Operation
|0033] As shown in Figure 2 and described below, the torque-transmitting
mechanisms and clutches shown in Figure 1 are selectively engageable to provide
multiple continuously variable speed ranges (V1-V4), fixed gear ratios (F1-F7) and an
electric drive mode (El).
Fixed Speed Ratios
[0034] A first forward speed ratio Fl is established with the engagement of first
clutch 72, second clutch 74 and third clutch 100. The first clutch 72 operatively connects
the input shaft 46 to the planet carrier assembly member 26. The second clutch 74
operatively connects the first ring gear member 18 to the second ring gear member 22.
The third clutch 100 operatively connects the first sun gear member 38 to two output
members, the first countershaft 78 and the second countershaft 80.
[0035] A second forward speed ratio F2 is established with the engagement of
first clutch 72, third clutch 100 and fourth clutch 104. The first clutch 72 operatively
connects the input shaft 46 to the planet carrier assembly member 26. The third clutch
100 operatively connects the first sun gear member 38 to two output members, the first
countershaft 78 and the second countershaft 80. The fourth clutch 104 operatively
connects the first ring gear member 18 to one of the two output members, the first
countershaft 78 and the second countershaft 80.
[0036] A third forward speed ratio F3 is established with the engagement of first
clutch 72, second clutch 74 and fourth clutch 104. The first clutch 72 operatively
connects the input shaft 46 to the planet carrier assembly member 26. The second clutch
74 operatively connects the first ring gear member 18 to the second ring gear member 22.
The fourth clutch 104 operatively connects the first ring gear member 18 to two output
members, the first countershaft 78 and the second countershaft 80.
(0037] A fourth forward speed ratio F4 is established with the engagement of first
clutch 72, fourth clutch 104 and sixth clutch 112. The first clutch 72 operatively
connects the input shaft 46 to the planet carrier assembly member 26. The fourth clutch
104 operatively connects the first ring gear member 18 to two output members, the first

countershaft 78 and the second countershaft 80. The sixth clutch 112 operatively
connects the second ring gear 22 to the output shaft 76.
[0038] A fifth forward speed ratio F5 is established with the engagement of first
clutch 72, second clutch 74 and sixth clutch 112. The first clutch 72 operatively connects
the input shaft 46 to the planet carrier assembly member 26. The second clutch 74
operatively connects the first ring gear member 18 to-the second ring gear member 22.
The sixth clutch 112"operatively connects the second ring gear 22 to the output shaft 76.
[0039] A sixth forward speed ratio F6 is established with the engagement of first
clutch 72, fifth clutch 108 and sixth clutch 112. The first clutch 72 operatively connects
the input shaft 46 to the planet carrier assembly member 26. The fifth clutch 108
operatively connects the first ring gear member 18 to two output members, the first
countershaft 78 and the second countershaft 80. The sixth clutch 112 operatively
connects the second ring gear 22 to the output shaft 76.
[0040] A seventh forward speed ratio F7 is established with the engagement of
first clutch 72, second clutch 74 and fifth clutch 108. The first clutch 72 operatively
connects the input shaft 46 to the planet carrier assembly member 26. The second clutch
74 operatively connects the first ring gear member 18 to the second ring gear member 22.
The fifth clutch 108 operatively connects the first ring gear member 18 to two output
members, the first countershaft 78 and the second countershaft 80.
Electric Drive Mode
[0041] An electric drive mode El is established with the engagement of the third
clutch 100. The third clutch 100 operatively connects the first sun gear member 38 to two
output members, the first countershaft 78 and the second countershaft 80. The input shaft
46 is not connected to the rest of the transmission 10 i.e. the engine is disconnected from
the transmission 10. Power is provided by the torque transmitting mechanisms 50, 58
functioning as electric motors.

Continuously Variable Range Modes
[0042] When the torque transmitting mechanisms 50, 58 are motors or include
motors, the transmission 10 can be operated as a CVT, by absorbing power with one
motor and using it in the other motor. The transmission 10 of Figure 1 is capable of
multiple continuously variable ranges or modes.
[0043] A first variable speed range VI is established with the engagement of first
clutch 72 and third clutch 100. The first clutch 72 operatively connects the input shaft 46
to the planet carrier assembly member 26. The third clutch 100 operatively connects the
first sun gear member 38 to two output members, the first countershaft 78 and the second
countershaft 80.
[0044] A second variable speed range V2 is established with the engagement of
first clutch 72 and fourth clutch 104. The first clutch 72 operatively connects the input
shaft 46 to the planet carrier assembly member 26. The fourth clutch 104 operatively
connects the first ring gear member 18 to two output members, the first countershaft 78
and the second countershaft 80.
[0045] A third variable speed range V3 is established with the engagement of first
clutch 72 and sixth clutch 112. The first clutch 72 operatively connects the input shaft 46
to the planet carrier assembly member 26. The sixth clutch 112 operatively connects the
second ring gear 22 to the output shaft 76.
[0046] A fourth variable speed range V4 is established with the engagement of
first clutch 72 and fifth clutch 108. The first clutch 72 operatively connects the input shaft
46 to the planet carrier assembly member 26. The fifth clutch 108 operatively connects
the first ring gear member 18 to two output member the first countershaft 78 and the
second countershaft 80.
[0047] The continuously variable ranges are input power split when third clutch
100 is engaged i.e. variable range VI is input split. Modes V2, V3 and V4 are compound
split. The input-power-split configuration has special advantage for vehicle launching,
because one of the electric motor-generators is at zero speed with the output at zero
speed; no power loop is present during launch. A compound power split configuration

has special advantage for operation with finite speed ratios because they have a definite
and relatively broad range where transmission power is fed forward and no power loop is
present in this range.
[0048] Each CVT range or mode is covered as the speed of one torque
transmitting mechanism is decreasing and the speed of the other is increasing. Thus, each
CVT mode corresponds to a shift between the fixed speed ratios of the transmission as
described above. Transitions between successive modes or ranges occur as the
countershaft gearing is selectively engaged and disengaged, and correspond to fixed
speed ratios of the transmission described above.
[0049] Thus, the same transmission gearing, compound planetary gearing, and
dual countershaft gearing can be useful in both stepped ratio and continuously variable
transmissions, and, in fact, a transmission can be constructed to operate effectively in
both ways. The transmission 10 can be operated practically as a stepped ratio
transmission, CVT, or combination of the two.
[0050] It should be noted that the first countershaft 78 and the second
countershaft 80 may be operatively connected to the output shaft 76 simultaneously so
that both countershafts transmit power to the output shaft.
[0051] The torque transmitting mechanisms 50, 58 selectively control the
rotational speed of the sun gears 42, 38. As described above, different speed ratios
between the input shaft 46 and the two countershafts 78 and 80 are established through
selective engagement of the torque transmitting mechanisms 50, 58 and clutches 72, 74,
100, 104, 112, 108 and corresponding control of sun gear speed.
[0052] While countershafts 78, 80 are employed together as a single operative
output means and the output shaft is employed directly as another output means in a
preferred embodiment, those skilled in the art will recognize a variety of different output
member configurations that may be employed within the scope of the invention to form
dual power paths from the gear set 14 to an output shaft 76. For example, members of a
second planetary gear set may be operatively connected to the first and second ring gears
18 and 22 and selectively engageable via clutches to an output shaft. Moreover, those

skilled in the art will recognize that it may be desirable to add additional gears to the
countershafts and the output shaft to increase the number of speed ratios available
between the countershafts and the output shaft.
[0053] In a preferred embodiment, the transmission 10 also includes an energy
storage device such as a battery 136 operatively connected via conductive wires 134 to
the motors of torque transmitting mechanisms 50, 58 to receive power from them and to
supply power to them. A controller 132 is operatively connected to the battery and the
motors to regulate the flow of power among them. Thus, a hybrid transmission is
formed. If torque transmitting mechanisms 50, 58 are electric generators, they can apply
torque indefinitely even' if their shafts are rotating. Thus, the shifts described above can
be transformed into compound power split operating ranges. That is, the braking torque
and speed applied by one of the torque transmitting mechanisms to spin the gear set
element corresponding to one of the countershafts slower than the input can be
transformed into power used by the other torque transmitting mechanism to spin the
element corresponding to the other countershaft faster than the input.
[0054] While the best modes for carrying out the invention have been described
in detail, those familiar with the art to which this invention relates will recognize various
alternative designs and embodiments for practicing the invention within the scope of the
appended claims.

WE CLAIM:
1. A power split electrically variable transmission with differential gearing without
transmitting all power through variable elements, the said vehicle transmission
comprising;
a stationary member (54);
a differential gear set (14) having first (18), second (22), third (26), fourth (38),
and fifth (42) coaxial gear elements operatively interconnected with one another;
an input shaft (46);
an output shaft (76);
Characterized in that,
first (72), second (74), third (100), fourth (104), fifth (112) and sixth (108)
torque-transmitting mechanisms selectively engageable to operatively connect one of
said gear elements with said stationary member or with said output shaft;
wherein the first (72) and second (74) of said torque-transmitting mechanisms
are capable of operatively exchanging power with one another;
wherein said torque-transmitting mechanisms are configured to produce an
input-split operating mode (V1), a first compound-split operating mode (V2), a second
compound-split operating mode (V3) a third compound-split operating mode (V4) of the
transmission (10);
wherein said third torque (100) transmitting mechanism is selectively engageable
to operatively connect one of said gear elements to the output shaft (76) to form an
input-split operating mode (V1), wherein said one of said gear element is continuously
connected to said first or second troque transmitting mechanism such that the
rotational speed of said one of said gear elements is proportional to the rotational
speed of said first or second torque transmitting mechanism;

wherein the differential gear set (14) is configured such that the rotational
speeds of two of the gear elements (26,38) may be independently established and
determine the rotational speeds of the three gear elements (42,18,22).
the fourth torque transmitting mechanism (104) is selectively engageable to
operatively connect the fourth gear element (38) to the output shaft (76) to form the
first compound-split operating mode (V2);
the fifth torque transmitting mechanism (112) is selectively engageable to
operatively connect the fifth gear elements (42) to the said output shaft (76) to form
the second compound-split operating mode (V3) and
the sixth torque transmitting mechanism (108) is selectively engageable to
operatively connect said fourth gear element (38) to the output shaft (76) to form the
third compound-split operating mode (V4);
2. A vehicle transmission (10) comprising;
a stationary member (54);
a differential gear set (14) having first (18), second (22), third (26), fourth (38),
and fifth (42) coaxial gear elements operatively interconnected with one another;
an input shaft (46);
an output shaft (76);
first (72), second (74), third (100), fourth (104), fifth (112) and sixth (108)
torque-transmitting mechanisms selectively engageable to operatively connect one of
said gear elements with said stationary member or with said output shaft;
wherein the first (72) and second (74) of said torque-transmitting mechanisms
are capable of operatively exchanging power with one another;

operation of said torque-transmitting mechanisms results in an input-split
operating mode (V1), a first compound-split operating mode (V2), a second compound-
split operating mode (V3) and a third compound-split operating mode (V4) of the
transmission (10);
the input shaft (46) is operatively connected to the first gear element (18);
the first torque-transmitting mechanism (72) is mounted to the stationary
member (54) and is selectively engageable to operativeiy connect to the second gear
element (22);
the second torque transmitting mechanism (74) is mounted to the stationary
member (54) and is selectively engageable to operatively connect to the third gear
element (26);
the third torque transmitting mechanism (100) is selectively engageable to
operatively connect one of said gear elements to the output shaft (76) to form an input-
split operating mode, wherein said one of said gear elements is operativeiy connected
to said first or second torque transmitting mechanism;
the fourth torque transmitting mechanism (104) is selectively engageable to
operatively connect the fourth gear element (22) to the output shaft (76) to form a first
compound- split operating mode (V2);
the fifth torque transmitting mechanism (112) is selectively engageable to
operatively connect the fifth gear elements (22) to said output shaft (76) to form the
second compound-split operating mode (V3); and
the sixth torque transmitting mechanism (108) is selectively engageable to
operatively connect said fourth gear element (18) to the output shaft (76) to form the
third compound-split operating mode (V4).
3. The transmission as claimed in claim 1, wherein the output member includes at
least one countershaft (78, 80).

4. The transmission as claimed in claim 2, optionally comprising a seventh torque
transmitting mechanism (50) selectively engageable to operatively connect one gear
element to another gear element in such a way as to cause all of the gear elements of
the gear set to rotate at substantially the same speed.
5. The transmission as claimed in claim 4, optionally comprising an eighth torque
transmitting mechanism (58) selectively disengageable to operatively disconnect the
input shaft (46) from the first gear element (38).
6. The transmission as claimed in claim 1, wherein the speed ratio between the
input shaft (46) and output shaft (76) is selectively variable by selectively engaging the
first (72) and second (74) torque transmitting mechanisms to control the rotational
speed of the second (22) and third (26) gear elements, respectively.
7. The transmission as claimed in claim 4:
wherein a first speed ratio (F2) is established between the input shaft (46) and
the output shaft (76), when the third (100) and seventh (54) torque transmitting
mechanisms are selectively engaged;
wherein a second speed ratio (F2) is established between the input shaft and the
output shaft, when third (100) and fourth (104) torque transmitting mechanisms are
selectively engaged;
wherein a third speed ratio (F3) is established between the input shaft (46) and
the output shaft (76), when the fourth (104) and seventh (54) torque transmitting
mechanisms are selectively engaged;
wherein a fourth speed ratio is established between the input shaft (46) and the
out shaft (76), when the fourth (104) and fifth (112) torque transmitting mechanisms
are selectively engaged;

wherein a fifth speed ratio (F5) is established between the input shaft (46) and
the output shaft (76), when the fifth (112) and seventh (54) torque transmitting
mechanisms are selectively engaged;,
wherein a sixth speed ratio (F6) is established between the input shaft and the
output shaft, when the fifth (112) and sixth (108) torque transmitting mechanisms are
selectively engaged; and
wherein a seventh speed ration (F7) is established between the input shaft (46)
and the output shaft (76), when the sixth (108) and seventh (54) torque transmitting
mechanisms are selectively engaged.
8. The transmission as claimed in claim 1, wherein the differential gear set (14)
includes a planet carrier (26), a first sun gear (38), a second sun gear (42), a first ring
gear (18) and a second ring gear (22); wherein the planet carrier (26) is equipped with
a first set of planet
pinion gears (30) which mesh with the first sun gear (38) and first ring rear (18) and a
second set of planet pinion gears (30) which mesh with the second sun gear (42) and
second ring gear (42); and wherein the first set of planet pinion gears (30) meshes with
the second set of planet pinion gears (34).
9. The transmission as claimed in claim 8, wherein the first gear element is the
planet carrier (26), the second gear element is one of the sun gears (38/42), the third
gear element is the other of the sun gears (38/42), the fourth gear element is one of
the ring gears (18/22);and the fifth gear element is the other of the ring gears (18/22).
10. The transmission as claimed in claim 2, wherein the first torque transmitting
mechanism (50) and the second torque transmitting mechanism (58) are electric motor-
generators.

11. The transmission as claimed in claim 1, optionally comprising an energy storage
device for accepting power from, and supplying power to, the first and second torque
transmitting mechanisms (50,58); and
a controller for regulating power flow among the energy storage device and the
first and second torque transmitting mechanisms (50,58).
12. The transmission as claimed in claim 11, wherein the output (76) may be driven
by power from the energy storage device alone, without power from the input (46),
through the action of at least one of the first or second torque transmitting mechanisms
(50,58).

ABSTRACT

A POWER SPLIT ELECTRICALLY VARIABLE TRANSMISSION WITH
DIFFERENTIAL GEARING WITHOUT TRANSMITTING ALL POWER
THROUGH VARIABLE ELEMENTS.
A vehicle transmission includes a differential gear set having five
coaxial gear elements and an output member. Two of the gear elements are
controllable via torque transmitting mechanisms such as electric motors to
establish a plurality of speed ratios between the input shaft and the output shaft.
Two of the other gear elements are selectively operatively connectable to an
output shaft via a gear arrangement that allows for a plurality of speed ratios
between the gear elements and the output shaft. Additional torque transmitting
mechanisms such as clutches are selectively engageable to provide continuously
variable speed ranges between the input shaft and the output shaft, fixed gear
ratios and an electric drive mode. The various speed ratios enable a plurality of
compound split operating modes as well as an input split mode.

Documents:

00943-kol-2006-abstract.pdf

00943-kol-2006-claims.pdf

00943-kol-2006-correspondence others-1.1.pdf

00943-kol-2006-correspondence others.pdf

00943-kol-2006-description(complete).pdf

00943-kol-2006-drawings.pdf

00943-kol-2006-form-26.pdf

00943-kol-2006-from-1.pdf

00943-kol-2006-from-2.pdf

00943-kol-2006-from-3.pdf

00943-kol-2006-from-5.pdf

00943-kol-2006-priority document-1.1.pdf

00943-kol-2006-priority document.pdf

943-KOL-2006-(28-03-2014)-ABSTRACT.pdf

943-KOL-2006-(28-03-2014)-ANNEXURE TO FORM 3.pdf

943-KOL-2006-(28-03-2014)-CLAIMS.pdf

943-KOL-2006-(28-03-2014)-CORRESPONDENCE.pdf

943-KOL-2006-(28-03-2014)-DESCRIPTION (COMPLETE).pdf

943-KOL-2006-(28-03-2014)-DRAWINGS.pdf

943-KOL-2006-(28-03-2014)-FORM-1.pdf

943-KOL-2006-(28-03-2014)-FORM-2.pdf

943-KOL-2006-(28-03-2014)-OTHERS.pdf

943-KOL-2006-(28-03-2014)-PETITION UNDER RULE 137.pdf

943-KOL-2006-ASSIGNMENT.pdf

943-KOL-2006-CANCELLED PAGES.pdf

943-KOL-2006-CORRESPONDENCE 1.1.pdf

943-KOL-2006-CORRESPONDENCE.pdf

943-KOL-2006-EXAMINATION REPORT.pdf

943-KOL-2006-FORM 18-1.1.pdf

943-kol-2006-form 18.pdf

943-KOL-2006-FORM 26.pdf

943-KOL-2006-GRANTED-ABSTRACT.pdf

943-KOL-2006-GRANTED-CLAIMS.pdf

943-KOL-2006-GRANTED-DESCRIPTION (COMPLETE).pdf

943-KOL-2006-GRANTED-DRAWINGS.pdf

943-KOL-2006-GRANTED-FORM 1.pdf

943-KOL-2006-GRANTED-FORM 2.pdf

943-KOL-2006-GRANTED-FORM 3.pdf

943-KOL-2006-GRANTED-FORM 5.pdf

943-KOL-2006-GRANTED-SPECIFICATION-COMPLETE.pdf

943-KOL-2006-OTHERS.pdf

943-KOL-2006-PETITION UNDER RULE 137.pdf

943-KOL-2006-REPLY TO EXAMINATION REPORT.pdf

943-KOL-2006-TRANSLATED COPY OF PRIORITY DOCUMENT.pdf

abstract-00943-kol-2006.jpg

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Patent Number

264175

Indian Patent Application Number

943/KOL/2006

PG Journal Number

50/2014

Publication Date

12-Dec-2014

Grant Date

11-Dec-2014

Date of Filing

19-Sep-2006

Name of Patentee

GM GLOBAL TECHNOLOGY OPERATION INC

Applicant Address

300 GM Renaissance Center Detroit, Michigan 48265-3000

Inventors:

#	Inventor's Name	Inventor's Address
1	ALAN G. HOLMES	6520 HADLEY HILLS COURT CLARKSTON, MICHIGAN 48348

PCT International Classification Number

F16H3/72; F16H37/02

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	11/263,175	2005-10-31	U.S.A.