Title of Invention

BALANCER FOR AN ENGINE

Abstract

A balancer for an engine comprising: a crankshaft (7); a balance shaft (32) being positioned substantially parallel to said crankshaft (7); a first balance weight (33) being provided on a distal end of said balancer shaft (32); a second balance weight (34) being provided on a distal end of said balancer shaft (32); and said first and second balance weights (33, 34) are rotated by a balancer driven gear (31) interlocked with the crankshaft (7) for rotating said first and second balance weights (33, 34); characterized by, an accessory (40) is driven by an accessory drive shaft (39) and an accessory drive gear (38) which is smaller than said second balance weight (34), characterized by, a gear (37) for driving said accessory (40) is provided to the inner side of the second balance weight (34) and said gear (37) is meshed with said accessory drive gear (38), and said accessory drive shaft (39) is provided between said second balance weight (34) and said balancer driven gear (31).

Full Text

FORM 2 THE PATENTS ACT 1970 [39 OF 1970] & THE PATENTS RULES, 2003 COMPLETE SPECIFICATION [See Section 10; rule 13] "BALANCER FOR AN ENGINE" HONDA GIKEN KOGYO KABUSHIKI KAISHA, a corporation of Japan, 1-1, Minamiaoyama 2-chome, Minato-ku, Tokyo, Japan, The following specification particularly describes the invention and the manner in which it is to be performed: The present invention relates to a balancer for an engine. [Prior Art] In Japanese published examined patent application No. Hei 2-118227, a balancer of an engine provided with a balance weight at both ends of a balancer shaft is disclosed. A balance weight on the side of a balancer gear is separate from the balancer gear, is formed so that the outer diameter is smaller than the root circle diameter and is arranged inside the balancer gear. [Problem to be Solved by the Invention] It is also conceivable that a balancer gear is made to have the form of a balance weight, however, as such a gear has an anomalous outline, it has a tendency for the precision of the gear to be deteriorated by the distortion after heat treatment. Then, when the balance weight is made separate from the balancer gear, the above-mentioned problem can be solved, however, in the case of a balance weight having a smaller diameter than the root circle diameter, the width of the balance weight is increased to secure sufficient unbalance amount, an engine is large-sized and the weight is increased. Then, the object of the invention is to provide a balancer that can acquire unbalance amount efficiently and can contribute to the -2- miniaturization and the lightening of an engine. [Means to Solve the Problem] To solve the problem, the invention Claim 1 is based upon a balancer of an engine configured so that a balance weight provided on a balancer shaft parallel to a crankshaft of the engine is rotated by a balancer gear interlocked with the crankshaft and is characterized in that the balance weight is formed as another member the diameter of which is larger than the root circle diameter of the balancer gear and is jointly fastened to the side of the balancer gear. The invention is based upon Claim 1 and is characterized in that the balancer gear is fitted to the balancer shaft via a spline, a fitting hole is provided to the end on the side of the balancer gear of the balancer shaft and an accessory driving member is fitted into the fitting hole. The invention is based upon a balancer of an engine in which a balance weight is provided to both ends of a balancer shaft parallel to a crankshaft of the engine and which is configured so that these balance weights are rotated by a balancer gear interlocked with the crankshaft and is characterized in that a balancer driven gear is provided to one end of the balancer shaft, a balance weight is integrated with the other end a gear for driving an accessory is provided to the inner side of the balance weight. -3- [Effect of the Invention) According to the invention, as the outer diameter of the balance weight is made larger than the root circle diameter of a balancer driven gear in structure that a separate balance weight is formed outside the balancer driven gear rotated by the transmission of power from a balancer drive gear fixed to the crankshaft, sufficient unbalance amount can be efficiently secured, as a result, the width of the balance weight can be minimized, the increase of the width of the engine is inhibited and the engine can be lightened and miniaturized. Also, as the balance weight is separate from the balancer driven gear, the balance weight the diameter of which is made larger than the root circle diameter of the balancer driven gear can be arranged very near to the balancer driven gear. In case a balance weight having such a large diameter is integrated with a balancer driven gear, the teeth of the balancer driven gear cannot be worked, however, such a manufacturing problem is not caused. Then, the balance weight can be easily fixed to the balancer shaft by jointly fastening the balance weight to the side of the balancer driven gear. According to the invention, as the balancer gear is fitted to the balancer shaft via a spline, the fitting hole is provided to the end on the side of the balancer gear of the balancer shaft and the accessory driving member is fitted into the fitting hole, the accessory can be -4- coaxially driven by the balancer shaft and as it does not require a large location to couple the accessory driving member though the balancer gear and the balancer weight are provided to the end of the shaft, the engine can be miniaturized. According to the invention, as the balance weight is provided to both ends of the balancer shaft, the balancer driven gear is provided to one end, the balance weight is integrated with the other end and the gear for driving the accessory is provided to the inner side of the balance weight, the gear for driving the accessory can be provided very near to the balance weight and it does not require a large location to attach the gear for driving the accessory. In addition, on the side of one end of the balancer shaft on which the balancer driven gear is provided, the driving shaft of one accessory is coaxially connected, the driving shaft of the other accessory is turned in parallel with the balancer shaft via the gear for driving the accessory on the side of the other end and the other accessory can be also arranged near one accessory. Therefore, the engine can be miniaturized. [Mode for carrying out the Invention] Referring to the drawings, one embodiment will be described below. Fig. 1 is a left side view showing a water-cooled four-cycle engine to which this embodiment is applied, Fig-2 is a sectional view showing a crankshaft, a main shaft and a countershaft of it and Fig. 3 is a sectional view showing a balancer mechanism. -5- As shown in Fig. 1, in this engine, a cylinder block 2 is provided over a crankcase 1, and a cylinder head 3 and a cylinder head cover 4 are provided on/over the cylinder block. A piston 5 is slid in the cylinder block 2 so that it can be reciprocated and rotates the crankshaft 7 (the reference number indicates the center) via a connecting rod 6. The crankshaft 7 is housed in the crankcase 1 and is engaged with a primary driven gear 11 integrated with a clutch 10 via a primary drive gear 9 provided on the crankshaft 7. The main shaft 12 and the countershaft 13 (the reference numbers indicate the respective center) respectively forming a transmission mechanism are arranged in parallel with the crankshaft 7 and plural transmission gears 14 and 15 provided on the respective shafts are always engaged. These are housed in a transmission case in the crankcase 1. The main shaft 12 is connected to the clutch 10 and intermittently operates the clutch 10 by a clutch lever 17. The combination of the transmission gears 14 and 15 is selected by a well-known gear selecting mechanism and a shift is output to an output sprocket 18 provided to one end of the countershaft 13. As shown in Fig. 2, the crankcase 1 is divided into right and left parts. The crankcase is composed of a case L 20 on the left side and a case R 21 on the right side, and a case L cover 22 and a case R cover 23 are attached to the respective outsides. -7- The crankshaft 7, the main shaft 12 and the countershaft 13 are respectively supported by a bearing between the case L 20 and the case R 21, and the crankshaft 7 is housed in the crankcase 8 formed in a sealed state between the case L 20 and the case R 21. The transmission mechanism including the main shaft 12, the countershaft 13 and the transmission gears 14 and 15 is housed in a transmission case 16 formed between the case L 20 and the case R 21 next to the crankcase 8. The crankcase 8 is partitioned by the transmission case 16 and a partition to be sealed. A clutch housing 25 is formed among the case R 21, the case R cover 23 and a clutch cover 24, and a wet clutch is housed here. The main shaft 12 connected to the clutch 10 is a hollow shaft, a push rod 26 pierces the main shaft and the clutch is intermittently operated by pushing one end of the push rod by a cam 27 formed at one end of the clutch lever 17. A reference number 28 denotes ACG provided to one end of the crankshaft 7. As shown in Fig. 3, a balancer drive gear 30 is provided in the vicinity of the primary drive gear 9 on the crankshaft 7, and a balancer driven gear 31 engaged with the balancer drive gear is provided at one end of a balancer shaft 32. The balancer shaft 32 is arranged in parallel with the crankshaft 7, is supported between the case L 20 and the case R 21 and balance weights 33 and 34 are provided at both ends One balance weight -8- 33 is provided separately from the balancer driven gear 31 and with one balance weight axially overlapped with the balancer driven gear, and the other balance weight 34 is integrated with the other end of the balancer shaft 32. An axial fitting hole 32a is provided to the end to which the balance weight 33 is provided of the balancer shaft 32, the end with an anomalous outline 36a formed on a driving shaft 36 of a water pump 35 is fitted into the axial fitting hole and is coupled to the axial fitting hole so that they can be coaxially rotated integrally and drives the water pump 35 together with the balancer shaft 32. A separate gear 37 is provided to a boss of the other balance weight 34 so that the gear can be integrally rotated. The gear 37 is engaged with an oil pump gear 38, the oil pump gear 38 rotates an integrated driving shaft 39 and drives an oil pump 40. The driving shaft 39 is supported by the case L 20 in parallel with the balancer shaft 32. The oil pump 40 is formed on the side of the case L 20 and in a part combined with the case R 21. For the supply of oil to the oil pump 40, oil is sent from an oil reservoir 41 formed at the bottom of the case R 21 of the crankcase 8 to an oil pan via a lead valve not shown by the rotation of a crank web 42. Oil sent from the oil-pump 40 in a state in which pressure is applied is supplied from a discharge passage 43 to required locations such as an oil -9- passage 46 provided to the core of the crankshaft 7 via an oil filter 44 provided on the inner side of the case L cover 22 and an oil passage 45 formed inside the case L cover 22. Fig. 4 shows the balancer shaft shown in Fig. 3 in an enlarged state and referring to Fig. 4, a balancer mechanism will be described further in detail below. One end of the balancer shaft 32 is protruded right in Fig. 4 from a ball bearing 50 provided to the case R, a boss 51 of the balancer driven gear 31 is fitted to the protruded end and is connected via a spline. The balance weight 33 is overlapped outside the balancer driven gear 31, is connected to the end of the balancer shaft 32 via a spline, and the balancer driven gear 31 and the balance weight 33 are fixed to the end of the balancer shaft 32 by a nut 53 via a washer 52. The balance weight 33 has non-circular form such as substantially a semicircle, the outer diameter R2 of a part having the maximum outer diameter is larger than the root circle diameter RI of the balancer driven gear 31 and is substantially equal to the outside periphery of the balancer driven gear 31. The maximum diameter is slightly larger, compared with that of the balance weight 34 on the left side, the thickness is substantially equal to a half and is substantially equal to the thickness of the tooth of the balancer driven gear 31. The maximum diameter of the balance weight 34 is substantially equal to the root circle diameter of the balancer driven gear 31 and is protruded outside from the case L. -10- The fitting hole 32a formed at the end of the balancer shaft 32 protruded from the nut 53 is a hole with an anomalous outline such as a square, the end with the anomalous outline 36a which is one end of the driving shaft 36 of the water pump which is one of accessories is fitted and locked into/in the fitting hole so that they can be integrally rotated. The end on the left side of the balancer shaft 32 is supported by a needle bearing 54 provided to the case L and a part protruded from the needle bearing 54 has a slightly larger diameter to be a boss 55 of the balance weight 34. The gear 37 for driving the oil pump which is one of accessories is press-fitted to the outside periphery of the boss 55, is integrated with the boss, one side is closely touched to the inner side 56 of the balance weight 34 and is fixed onto the inner side. The width of the gear 37 is wider than that of the oil pump gear 38. The oil pump gear 38 is locked in the driving shaft 39 by a pin 57 and is prevented from falling by a snap ring 58. Next, the action of this embodiment will be described. When the crankshaft 7 is rotated, the balancer shaft 32 is reversely rotated with the balancer shaft interlocked with the crankshaft 7 via the balancer drive gear 30 and the balancer driven gear 31, the balance weights 33 and 34 are integrally rotated and the vibration of the crankshaft 7 is reduced. -11- Simultaneously, a driving part of the water pump 35 is integrally rotated via the driving shaft 36 by the rotation of the balancer shaft 32 and cooling water is equipped. Simultaneously, the oil pump 40 is driven by rotating the oil pump gear 38 by the gear 37 integrated with the balance weight 34 and oil is supplied to required locations such as the crankshaft 7. As the separate balance weight 33 is arranged outside the balancer driven gear 31 rotated by the transmission of power from the balancer drive gear 30 fixed to the crankshaft 7 and the outer diameter R2 of the balance weight 33 is made larger than the root circle diameter Rl of the balancer driven gear 31, sufficient unbalance amount can be efficiently secured, as a result, the width of the balance weight 33 can be minimized, the increase of the width of an engine is inhibited and the engine can be lightened and miniaturized. In addition, as the balance weight 33 is separate from the balancer driven gear 31, the balance weight 33 larger than the root circle diameter Rl of the balancer driven gear 31 can be arranged very near to the balancer driven gear 31. In case the balance weight 33 having such a large diameter is integrated with the balancer driven gear 31, the gear has a tendency for the precision to be deteriorated by the distortion after heat treatment because the balancer driven gear 31 has an anomalous outline and the teeth having unbalanced form cannot be worked, however, such a manufacturing problem -12- is not caused. Then, the balance weight 33 can be fixed to the balancer shaft 32 easily and compactly by jointly fastening the balance weight 33 to the side of the balancer driven gear. Also, as the balancer driven gear 31 is fitted to the balancer shaft via a spline, the fitting hole 32a is provided to the end on the side of the balancer driven gear of the balancer shaft 32, the fitting end 36a of the driving shaft 36 of the water pump is fitted into the fitting hole 32a and the fitting end and the fitting hole are coupled by fitting, the water pump 35 which is an accessory can be coaxially driven by the balancer shaft 32 and as it does not require a large location to couple the driving shaft 36 though the balancer driven gear 31 and the balance weight 33 are provided to the end of the shaft, the engine can be miniaturized. Further, as the balance weights 33 and 34 are provided to both ends of the balancer shaft 32, the balancer driven gear 31 is provided to one end (the side R), the balance weight 34 is integrated with the other end, the gear 37 for driving the accessory that drives the oil pump gear 38 can be provided to the inner side 56 of the balance weight 34 and it does not require a large location to attach the gear 37, the engine can be miniaturized. In addition, the driving force transmission path to the oil pump 40 is turned and the oil pump 40 can be arranged near -13- the water pump 35 by coaxially coupling the driving shaft 36 of the water pump 35 to the side of one end of the balancer shaft 32 on which the balancer driven gear 31 is provided and arranging the driving shaft 39 to which the oil pump gear 38 engaged with the gear 37 for driving the accessory provided at the other end is provided in parallel with the balancer shaft 32. Therefore, the engine can be further miniaturized. The invention is not limited to the above-mentioned embodiment and various transformation and application are allowed in the principle of the invention. For example, required unbalance amount is secured by building a part made of material having large specific gravity between the balancer driven gear 31 and the balance weight 33 and the engine can be also miniaturized and lightened. -14- We claim: 1. A balancer for an engine comprising: a crankshaft (7); a balance shaft (32) being positioned substantially parallel to said crankshaft (7); a first balance weight (33) being provided on a one end of the balancer shaft (32); a second balance weight (34) being provided on a distal end of said balancer shaft (32); and said first and second balance weights (33, 34) are rotated by a balancer driven gear (31) interlocked with the crankshaft (7) for rotating said first and second balance weights (33, 34); characterized by, an accessory (40) is driven by an accessory drive shaft (39) and an accessory drive gear (38) which is smaller than said second balance weight (34), and a gear (37) for driving said accessory (40) is provided to the inner side of the second balance weight (34) and said gear (37) is meshed with said accessory drive gear (38), and said accessory drive shaft (39) is provided between said second balance weight (34) and said balancer driven gear (31). 2. The balancer for an engine as claimed in claim 1, wherein: the balancer gear (31) is fitted to the balancer shaft (32) via a spline; a fitting aperture (32a) is provided to an end on the side of the balancer gear (31) of the balancer shaft (32) ; and an accessory driving member (36a) is fitted into the fitting aperture (32a). 3. A balancer for an engine as claimed in claim 1, wherein: -16- a balance weight (33) provided on a balancer shaft (32), said balancer shaft (32) being parallel to a crankshaft (7) of the engine, said balance weight (33) being rotated by a balancer gear (31) interlocked with the crankshaft (7); said balancer weight (33) includes a diameter that is larger than a root circle diameter of the balancer gear (31); and said balancer weight \33) being jointly fastened onto a side of the balancer gear. 4. A balancer of an engine substantially as hereinbefore described with reference to the accompanying drawings. Dated this 15th day of May, 2002 [RAJAN AILAVADI] OF REMFRY & SAGAR ATTORNEY FOR THE APPLICANTS

Documents:

435-mum-2002-abstract(19-04-2007).doc

435-mum-2002-abstract(19-04-2007).pdf

435-mum-2002-cancelled pages(15-05-2002).pdf

435-mum-2002-claims(granted)-(10-01-2008).doc

435-mum-2002-claims(granted)-(10-01-2008).pdf

435-mum-2002-correspondence(10-01-2008).pdf

435-mum-2002-correspondence(ipo)-(10-01-2007).pdf

435-mum-2002-drawings(10-01-2008).pdf

435-mum-2002-form 1(19-04-2007).pdf

435-mum-2002-form 18(07-04-2006).pdf

435-mum-2002-form 2(granted)-(10-01-2008).doc

435-mum-2002-form 2(granted)-(10-01-2008).pdf

435-mum-2002-form 3(13-04-2004).pdf

435-mum-2002-form 3(15-05-2002).pdf

435-mum-2002-form 3(19-04-2007).pdf

435-mum-2002-form 5(15-05-2002).pdf

435-mum-2002-petition under rule 137(19-04-2007).pdf

435-mum-2002-petition under rule 138(19-04-2007).pdf

435-mum-2002-power of attorney(04-07-2002).pdf

435-mum-2002-power of attorney(19-04-2007).pdf

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