Title of Invention

FUEL INJECTION SYSTEM OF INTERNAL COMBUSTION ENGINE

Abstract To provide a fuel injection system of an internal combustion engine where operational status of the engine is sectioned into plural areas and a correction factor of the frequently used area can be precisely updated. [Solution] Basic fuel injection quantity is calculated based upon engine speed Ne and a throttle angle Th, referring to a first map 40. A variable KBUK for correction corresponding to a current area is read. A variable K02 as feedback correction quantity depending upon the density of 02 in an exhaust system is calculated to approach air-fuel ratio calculated beforehand. Correction by KBUK and K02 is applied to the basic fuel injection quantity so as to determine final fuel injection quantity and fuel is injected. The variation of K02 for a reference value is transferred to KBUK at a predetermined cycle and at a predetermined rate and the KBUK is stored in a nonĀ¬volatile storage. In first to tenth areas 70a to 70j, in a location Nel in which engine speed Ne is the same, the smaller the throttle angle Th is, the smaller the height of the area in an axial direction of the throttle angle is also. [Selected Drawing] Fig. 3
Full Text [Document Name] Specification
[Title of the Invention] FUEL INJECTION SYSTEM OF INTERNAL COMBUSTION ENGINE
[Technical Field]
[0001]
The present invention relates to a fuel injection system of an internal combustion engine where fuel injection quantity is calculated based upon the number of revolutions of a crank of an internal combustion engine and a throttle angle, final fuel correction quantity is calculated by operating feedback correction quantity based upon an output signal output from an 02 sensor provided to an exhaust system to approach air-fuel ratio calculated beforehand, and learning control based upon the feedback correction quantity is executed.
[Background Art]
[0002J
Fuel injection quantity for acquiring ideal air-fuel ratio of an internal combustion engine is substantially set based upon the number of revolutions of a crank and intake quantity, however, in place of the intake quantity, a throttle angle is sometimes used. When a throttle angle is large, actual intake quantity and the throttle angle are considerably closely correlated, however, when a throttle angle is small, correlation with actual intake quantity decreases because of the viscosity of air and the effect of a bypass passage and others, and an error with the ideal air-fuel ratio may be made based upon the fuel injection

quantity acquired based upon the throttle angle.
[0003]
In an area in which a throttle angle is small, a method of estimating intake quantity based upon a negative pressure sensor is conceivable. In a patent document 1, a negative pressure sensor is provided to an intake system and when there are the variation in environment of a vehicle and aged deterioration, fuel injection quantity is controlled based upon the output of the sensor. However, the negative pressure sensor is higher-priced, compared with a throttle angle sensor and the cost is increased.
[0004]
Then, in a patent document 2, it is proposed that feedback correction quantity is operated based upon an output signal output from an 02 sensor provided to an exhaust system to approach air-fuel ratio calculated beforehand, fuel injection quantity is corrected and final fuel injection quantity is determined. In the patent document 2, fuel injection quantity and ignition timing are controlled based upon stored learned correction quantity based upon the feedback correction quantity,
[0005J
In a patent document 3, learning control that operational status of an engine is sectioned into plural areas and feedback correction quantity for reducing an extra amount or supplementing a short amount in the quantity of supplied fuel is calculated by a feedback control system is performed. As described above, suitable

control according to the sectioned area is enabled by setting an individual control parameter to the individual area plurally sectioned. [0006]
[Patent document 1] JP-A Ho. H5-59997 [Patent document 2] JP-A No. H9-4554 [Patent document 3] JP-B No. H5-26935 [Disclosure of the Invention] [Problem to be Solved by the Invention] [0007]
According to a control method disclosed in the patent document 3, control according to the plural areas is enabled, however, it is desirable that a control parameter is suitably updated based upon an 02 feedback value and others to correspond to environmental variation. [0008]
However, the plural areas sectioned according to the operational status of the engine are not necessarily executed at the same frequency, when a general vehicle is run in a town, the running in a state in which a throttle angle is small is considerably frequent, and a control parameter is frequently updated in the area corresponding to this state, however, a control parameter of the area corresponding to a state in which the throttle angle is large is not updated so much. Therefore, for example, immediately after the vehicle enters a highway from the town and the running transfers to running in which the throttle angle is increased, the corresponding control

parameter is not suitable and ideal air-fuel ratio is not immediately acquired. [0009]
Further, as running in a state in which a throttle angle is small is considerably frequent when a general vehicle is run in a town, it is desirable that a correction factor for such an area is particularly precisely updated. [0010]
The invention is made in view of such a problem and its object is to provide a fuel injection system of an internal combustion engine where operational status of the engine is sectioned into plural areas, a control parameter recorded every area can be as promptly updated to a suitable value as possible and further, a correction factor for a frequently used area can be precisely updated. [Means for Solving the Problem] [0011]
The fuel inj ection system of the internal combustion engine according to the invention is provided with the following features. [0012]
According to a first feature of the present invention, there is provide a fuel injection system of an internal combustion engine provided with basic injection quantity calculating means that calculates basic fuel injection quantity based upon a throttle angle and engine speed, referring to a basic fuel injection map based upon the throttle angle of a throttle valve provided to an intake

system of an internal combustion engine and the engine speed of the internal combustion engine, feedback correction factor calculating means that calculates a feedback correction factor for feedback-controlling fuel injection at a predetermined cycle based upon an output signal output from an 02 sensor provided to an exhaust system, final fuel injection quantity calculating means that determines final fuel injection quantity by multiplying the basic fuel injection quantity by the feedback correction factor to approach target air-fuel ratio and feedback learned correction factor storage means that store the feedback correction factor in a non-volatile storage as a learned correction factor at predetermined timing, the feedback learned correction factor storage means stores the calculated learned correction factor every corresponding area in the basic fuel injection map sectioned into plural areas according to operational status beforehand, the plural areas are compared in the same location in the engine speed in the basic fuel injection map and in the area in which the throttle angle is smaller, the height of the area in an axial direction of the throttle angle is smaller. [0013]
As described above, the area ordinarily used is limited by setting so that the smaller the throttle angle is, the smaller the height of the area is also and a correction factor of the area can be precisely updated. [0014]

According to a second feature of the present invention, the side on which the throttle angle is the largest out of the plural areas is set to one area independent of the engine speed and the side on which the throttle angle is the smallest is set to plural areas according to the engine speed. [0015]
It is reasonable that the side on which the throttle angle is the largest is set to one integrated area because there is difference in a frequency in use based upon engine speed. In the meantime, the side on which the throttle angle is the smallest is set to plural areas according to engine speed and as a result, more precise control is enabled. Locations in which the throttle angle is middle may be sorted into suitable areas according to a condition of design. [0016]
According to a third feature of the present invention, a representative area is provided to one area set on the side on which the throttle angle is the largest and a learned correction factor acquired in relation to the representative area is reflected as that of the whole one area. [0017]
The learned correction factor can be simply and precisely applied to the whole one area by calculating the learned correction factor based upon the representative area.

[0018]
According to a fourth feature of the present invention, the area includes an idle area corresponding to idling, a large throttle angle area on the side on which the throttle angle is the largest and a middle/small throttle angle area except the idle area and the large throttle angle area and a learned correction factor of the middle/small throttle angle area is calculated based upon a learned correction factor of the idle area and a learned correction factor of the large throttle angle area. [0019]
When the three areas are used as described above, the number of provided areas is reduced, storage capacity for storing parameters such as a learned correction factor is reduced, and a procedure for control is also simplified. [0020]
According to a fifth feature of the present invention, there is provided a fuel injection system of an internal combustion engine which is provided with basic injection quantity calculating means that calculates basic fuel injection quantity based upon a throttle angle and engine speed, referring to a basic fuel injection map based upon the throttle angle of a throttle valve provided to an intake system of the internal combustion engine and the engine speed of the internal combustion engine, feedback correction factor calculating means that calculates a feedback correction factor for feedback-controlling fuel injection at a predetermined cycle based upon an output

signal output from an 02 sensor provided to an exhaust system, final fuel injection quantity calculating means that determines final fuel injection quantity by multiplying the basic fuel injection quantity by the feedback correction factor to approach target air-fuel ratio and feedback learned correction factor storing means that store the feedback correction factor as a learned correction factor in a non-volatile storage at predetermined timing and in which the final fuel injection quantity calculating means calculates final fuel injection quantity using the learned correction factor in operation status in which no feedback control based upon the output signal from the 0^ sensor is made, and estimation-correcting means that holds a basic rate of a change of the learned correction factor every plural areas or every some adjacent areas in a predetermined recording unit and corrects the learned correction factor of at least one of the other areas based upon a current area variation and a corresponding basic rate of a change when the current area variation for a reference value of the learned correction factor in a current area is equal to or exceeds predetermined quantity. [0021]
As described above, when the operational status of the engine is sectioned into plural areas and a correction factor of one area is updated, correction factors of the other areas can be updated to appropriate values as promptly as possible by estimation-correcting about the

other areas according to a trend of its variation. [0022]
According to a sixth feature of the present invention, in the estimation-correcting means, predetermined limitation is provided to the correction quantity of the other areas. Estimated correction is estimation to the end and it is desirable that excessive correction is prevented. Then, a correction factor of an area to be a target of estimated correction is prevented from being excessively corrected by providing predetermined limitation. [0023]
According to a seventh feature of the present invention, the limitation is equivalent to a variation of a current area. As described above, it is suitable to use the variation of the current area variation for the limitation and in addition, a process is simple. [0024]
According to an eighth feature of the present invention, the plural areas include an independent idling area corresponding to idling. The idling area is frequently used, in addition, is an area having large disturbance, and as the idling area is independent, minute correspondence is enabled. [0025]
According to a ninth feature of the present invention, when the current area variation is equal to or exceeds predetermined quantity in idling of a vehicle, the correction factors of all the areas except the idling area

are estimation-corrected based upon a variation of the learned correction factor and the basic rate of a change. As disturbance is large in the idling area, it is suitable to precisely correct all the other areas based upon the basic rate of a change.
[Effect of the Invention]
[0026]
According to the fuel injection system of the internal combustion engine of the present invention, the operational status of the engine is sectioned into plural areas, a control parameter recorded every area can be updated to an appropriate value as promptly as possible, and further, the correction factor of the frequently used area can be precisely updated.
[Best Mode for Carrying Out the Invention]
[002-7]
An embodiment of a fuel injection system of an intPrnal combustion engine according to the present invention will be described below. A fuel injection system of an internal combustion engine equivalent to this embodiment and shown in the attached drawings. Figs. 1 to 12 is applied to a vehicle such as a motorcycle and a four-wheeled vehicle.
[0028]
As shown in Fig. l, the fuel injection system 10 of the engine (the internal combustion engine) in this embodiment is applied to an engine system 11 of a motorcycle. The engine system 11 includes the engine 12, a

controller 14, a fuel injection 16, an ignition plug 18, a throttle valve 20 provided to an intake pipe, a catalyst 22 and an 02 sensor 24 respectively provided to an exhaust pipe, an acceleration sensor 26 and a revolution speed sensor 30 that detects the revolution speed of a crank 28.
[0029]
The controller 14 reads a value of the acceleration sensor 26 and opens and closes the throttle valve 20 via an actuator 32. The 02 sensor 24 detects the density of 02 in the exhaust pipe and supplies its value to the controller 14 . The controller 14 executes predetermined operation based upon signals from the acceleration sensor 26, the 02 sensor 24, the revolution speed sensor 30 and others, judges injection quantity and ignition timing, and controls the fuel injection 16 and the ignition plug 18. To facilitate understanding, a manipulated variable of the acceleration sensor 26 and an angle of the throttle valve 20 (hereinafter called a throttle angle Th} shall be proportional and the throttle angle Th can be specified by detecting a signal from the acceleration sensor 26. Means for detecting the throttle angle Th is not limited to the acceleration sensor 26 and for example, a throttle angle sensor may be also provided to the throttle valve 20.
[0030]
Different control over the controller 14 can be realized by software and first to third control methods will be described below. The first control method is based upon a first map 40, the second method is based upon a

second map 80 (see Fig. 10), and the third control method is based upon a third map 90 (see Fig. 11). First, the first control method will be described. [0031]
As shown in Fig. 2, in the first control method, the controller 14 is provided with a basic fuel injection quantity calculating unit (basic fuel injection quantity calculating means) 42 that calculates basic fuel injection quantity based upon engine speed Ne acquired from the revolution speed sensor 30 and the throttle angle Th acquired from the acceleration sensor 26, referring to the first map 40, an 02 feedback unit (a feedback correction factor calculating means) 44 that corrects a feedback correction factor based upon the density of 02 (an output signal) output from the 02 sensor 24 so that the density is close to ideal air-fuel ratio (target air-fuel ratio) and executes feedback control, a correction quantity recording unit 4G that can read and write a parameter, a correcting unit 48 that corrects based upon correction quantity acquired in the 02 feedback unit 44 in consideration of the basic fuel injection quantity and a fuel injection time calculating unit (final fuel injection quantity calculating means) 50 that calculates fuel injection time corresponding to acquired final fuel injection quantity. The controller 14 is also connected to a water temperature sensor 51 that detects the water temperature of the engine 12. [0032]
The fuel injection time calculating unit 50 instructs

the fuel injection 16 to open at predetermined timing based upon the acquired fuel injection time so as to inject fuel. Hereby, air-fuel ratio varies, its effect is detected by the 02 sensor 24 in the exhaust pipe, and a feedback system is formed. [0033]
The 02 feedback unit 44 is provided with a rich/lean determining unit 52 that determines how exhaust is rich or lean based upon the density of 02 and a parameter calculating unit (feedback learned correction factor storage means) 54 that calculates parameters for correcting the feedback correction factor and the basic fuel injection quantity based upon the result of the determination. The 02 feedback unit 44 does not execute feedback control during warming up when operation is started. [0034]
The parameter calculating unit 54 records a predetermined parameter in the correction quant ity recording unit 46 at a predetermined cycle and reads these parameters when the system is activated (when an ignition key is turned on). The correction quantity recording unit 46 is non-volatile recording means and is an EEPROM and a flash memory for example. [0035]
Figs. 1 and 2 show an example of a single cylinder, however, needless to say, the engine system can be similarly configured in an engine with plural cylinders. In the case of the engine with plural cylinders, the

controller 14 and the acceleration sensor 26 for example
can be shared.
[0036]
As shown in Fig. 3, the first map 40 is two-dimensional data referred based upon the engine speed Ne and the throttle angle Th and is stored in a predetermined storage device. Fig. 3 schematically shows the contents of the first map 40 to facilitate understanding and any recording mode may be adopted in the storage device. [0037]
In the first map 40, the basic fuel injection quantity corresponding to the engine speed Ne and the throttle angle Th is recorded. The basic fuel inj ection quantity is set based upon calculation and simulation or experiments beforehand to acquire ideal air-fuel ratio. That is, combustion considerably close to the ideal air-fuel ratio can be realized by injecting fuel based upon the basic fuel injection quantity, however, combustion off the ideal air-fuel ratio may be made depending upon the operation of the engine 12, and to eliminate such an error, feedback by the 02 sensor 24 is made. In the first map 40, the data range upward to the right. This reason is that the throttle angle Th is also large when the engine speed Ne is great. [0038]
A map 60 shown in Fig. 4 schematically shows a degree of an error with the ideal air-fuel ratio in experimental operation by the basic fuel injection quantity based upon

the first map 40 when no feedback control by the 02 sensor 24 is executed (that is, in an open loop). The map 60 shows that the darker color in a piece is, the larger the error is and that the lighter the color is, the smaller the error is. The map 60 is utilized in the estimation learning of feedback control. Concretely, the variation due to large discrepancy (a variation) in estimation of driveability can be inhibited by using the data in the map 60 for an initial value of discrepancy in estimation learning. [0039]
As understandable from Fig. 4, the error with the ideal air-fuel ratio can be sectioned into areas to some extent and concretely, there is a trend that the larger the throttle angle Th is, the smaller the error is and the smaller the throttle angle Th is, the larger the error is. In addition, there is a trend that the larger engine speed Ne is, the larger the error is and the smaller engine speed He is, the smaller the error is. Further, in an area corresponding to idle speed, there is a trend that the error is large. [0040]
To consider such trends, it is reasonable to similarly control over areas having the same trend together. That is, it is expected that if the same control is applied to locations having the same trend, results having the same trend are acquired to an extent that there is substantially no problem and in addition, the number of parameters is to

be inhibited by the number of areas. The first map 40 in Fig. 3 shows plural areas sectioned beforehand according to deviation from the ideal air-fuel ratio and operational status (that is, the engine speed Ne and the throttle angle Th) .
[0041]
As shown in Fig. 3, it is suitable that the whole area is sectioned into approximately ten sections for example, the whole area is sectioned into nine areas by substantial vertical lines 62 and 64 respectively sectioning the engine speed Ne and upward straight lines
(or upward curves) 66 and 68 respectively sectioning the throttle angle Th, and the whole area is sectioned into total ten areas by adding the independent idle area to the nine areas. The straight lines 66 and 68 correspond to an upward trend in the whole first map 40. The lines 62 and 64 and the straight lines 66 and 68 are set so that errors shown in the map 60 in Fig. 4 are in the substantial same range in the same area.
[0042]
A first area 70a is the idle area, a second area 70b, a third area 70c and a fourth area 70d are areas where the engine speed Ne is the lowest, and the above-mentioned areas are set in order from the area in which the throttle angle Th is the lowest. A fifth area 70e, a sixth area 70f and a seventh area 70g are areas where the engine speed Ne is medium and are set in order from the area in which the throttle angle Th is the lowest. An eighth area 70h, a

ninth area 70i and a tenth area 70j are areas where the engine speed Ne is the highest and are set in order from the area in which the throttle angle Th is the lowest. [0043]
As understandable from Fig. 3, to compare the areas having the same engine speed Ne, the smaller the throttle angle Th is, the smaller the height H of the area is also. For example, in the areas where the engine speed Ne is low and has a fixed value Nel, the height H4 of the upper fourth area 70d, the height H3 of the middle third area 70c and the height H2 of the lower second area 70b become lower in their order. [0044]
Hereby, the ordinarily used areas the throttle angle Th of which is small (that is, the first area 70a, the second area 70b, the fifth area 70e, the eighth area 70h and others) are limited and KBUK which is a correction factor of the areas can be updated precisely and frequency [0045]
To take a look at Fig. 3, it is considered that the first area 70a may be included in the second area 70b, however, the idle area is frequently used, in addition, is an area in which disturbance is frequency caused, and fine handling can be expected by setting the idle area as an independent area. [0046]
As for the first area 70a to the tenth area 70j, a variable K02 [x] and a variable KBUK [x] (correction

factors) respectively for executing 02 feedback are provided. In this case, its argument x is an identifier equivalent to any of ten areas and any value of 1 to 10 is input. Hereinafter, the variable K02 [x] and the variable KBUK [x] will be simply and representatively called called K02 and KBUK if necessary.
[0047]
In the 02 feedback, K02 is a primarily used variable every predetermined control period and basically, the 02 feedback is executed based upon K02 to approach the ideal air-fuel ratio. KBUK is an auxiliary variable of K02 and complements K02 in a suitable period to restore K02 to an initial value 1.
[0048]
In other words, K02 is the variable for corresponding to a state transition process in control or for corresponding to considerably frequent variation and KBUK is the variable for corresponding to a medium- and long-term trend including a medium period, a long period and an aperiodic frequency. KBUK is recorded in the correction quantity recording unit 46 at a predetermined cycle, its value is held also after the system is halted (after the ignition key is turned off), the value is read when the system is started, and so-called learning control is executed.
[0049]
Concretely, K02 as feedback correction quantity is calculated based upon a degree of the richness or the

leanness exhaust of gas determined by the rich/lean determining unit 52 based upon the density of 02 read from the 02 sensor 24. In this case, a total correction factor KT is acquired by calculating the following expression (1). K02 is a value in a range of +0.5 to +2.0 for example, and K02 and KBUK are a reference value 1 in a default mode. KTW denotes an engine water temperature factor, KBUR denotes an aged deterioration supplementary factor, KALT denotes an environment supplementary factor, and to simplify explanation, KTW, KBUR and KALT shall be 1.
KT - K02 * KTW * KBUK * KBUR * KALT (1)
[0050]
Afterward, corrected fuel injection quantity Tl is acquired by calculating the following expression (2) in which TO represents the basic fuel injection quantity read from the first map 40 and is supplied to the fuel injection time calculating unit 50. That is, the basic fuel injection quantity TO is multiplied by KT as the feedback correction factor and the final fuel injection quantity is determined to approach the ideal air-fuel ratio.
Tl - TO * KT (2)
[0051]
K02 acts so that fuel injection quantity is less than its current value when K02 is in a range of +0.5 to +1.0, acts so that fuel injection quantity is more than its current value when K02 is in a range of +1.0 to +2.0, and the feedback system is formed. When combustion is made at the ideal air-fuel ratio, K02 is 1. As for 02 feedback

control, a feedback system in which K02 is a plus or minus value, addition or subtraction to/from the basic fuel injection quantity is made, further, predetermined gain or a predetermined correction factor (for example, a PID factor) is multiplied and its result is output for example may be also adopted. [0052]
K02 can also correspond to considerably frequent variation, however, as a long-period or aperiodic variation component is also superimposed, it is desirable that the component is recorded in the correction quantity recording unit 46 after transition to KBUK. Then, a correction factor reflecting process for reflecting a value of K02 in KBUK at a predetermined rate is executed. [0053]
That is, K02 is put close to the reference value 1 at a predetermined rate, maintaining a value acquired by "K02 v KBUK" and a variation from the reference value 1. is complemented in KBUK. For example, K02flUE = 1.2 (a subscript AVE shows an average value (for example, an average of movement in a predetermined period)), when KBUK is 1.0 {K02AVE * KBUK = 1.2), conversion is made so that K02 is 1.1 and KBUK is 1.0909 (K02AVE * KBUK a 1.2). K02 or its average value approaches 1 by repeating such a conversion process at a predetermined cycle, only the considerably frequent component is included, and a frequent component to some extent and medium-period, long-period or aperiodic components are included in KBUK. As KBUK complements K02AVE

which is an average value of K02, a component of an error (noise and others) is removed. [0054]
Fig. 5 shows the transition of K02AVE and KBUK. KBUK is converted at a predetermined cycle or is converted when K02AVE is equal to or above a predetermined value or is equal to or below the predetermined value. In Fig. 5, K02BVE and KBUK smoothly vary, however, they microscopically vary stepwise. [0055]
As described above, as KBUK is complemented and converted so that K02RVE approaches 1.0 and is recorded in the correction quantity recording unit 46, a value recorded before the system is halted is reflected in KBUK when the system is restarted after the system is halted, even when K02 is initialized to 1, the feedback system is immediately restored to a state before the system is halted, the combustion of the engine 12 is close to the ideal air-fuel ratio, and the effect of learning control is acquired. [0056]
The above-mentioned K02 and KBUK are provided to each of the first area 70a to the tenth area 70j and suitable feedback control according to a characteristic of each area is executed. [0057]
The K02 and KBUK are provided to each of the first area 70a to the tenth area 70j, are processed and updated, however, these areas 70a to 70j are not necessarily

executed at the same frequency, and for example, when the vehicle is run in a town, running in a condition in which the throttle angle Th and the engine speed Ne are small is frequent. In an actual running condition, for example, in the first area 70a, the second area 70b, the third area 70c, the sixth area 70f and the seventh area 70g, corresponding K02 and KBUK (that is, K02 [1], K02 [2], K02 [3], K02 [6], K02 [7] , KBUK [1] , KBUK [2] , KBUK [3] , KBTJK [6] , KBUK [7] ) are frequently updated. In the meantime, when no special means is provided, in the fourth area 70d, the fifth area 70e, the eighth area 70h, the ninth area 70i and the tenth area 70j, corresponding K02 and KBUK (that is, K02 [4], K02
[5] , K02 [8] , K02 [9] , K02 [10] , KBUK [4] , KBUK [5] , KBUK
[8], KBUK [9], KBUK [10]) are not frequently updated so much.
[0058]
To enable also promptly updating a parameter in such areas, the following estimation learning control is executed in the fuel injection system 10 in this embodiment.
[0059]
In estimation learning control, a basic rate of a change RATE [x] of basic fuel injection quantity in each of areas 70a to 70j is calculated beforehand and is recorded in a predetermined recording unit.
[0060]
As shown in Fig. 6, the basic rate of a change RATE
[x] is provided corresponding to the first area 70a to the tenth area 70j and shows a degree of a relative change of

KBUK among respective areas 70a to 70j . The basic rate of a change RATE [x] is acquired by an experiment for example, the variation of KBUK when air quantity passing the throttle varies by predetermined quantity is measured as basic data, values of RATE [2] to RATE [10] of the other areas are adjusted so that RATE [1] of the first area 70a is 1 with ratio between areas held, and the values are recorded. The reason why RATE [1] of the first area 70a is set to 1 as .a reference value is that it is convenient so as to execute estimation learning control in an idle area as described later.
[0061]
In addition, an average value of RATE [4], RATE [7] and RATE [10] in the upper stage is calculated as the average of the upper stage RATEl, an average value of RATE
[3], RATE [6] and RATE [9] in a middle stage is calculated as the average of the middle stage RATE2, and an average value of RATE [2], RATE [5] and RATE [8] in a lower stage is calculated as the average of the lower stage RATE3, and the average values are recorded.
[0062]
The timing of calculating the basic rates of the change RATE [x], RATEl, RATE2 and RATE3 may be also in the initial operation of the vehicle (timing equivalent to a so-called break-in), the timing may be also in the stage of adjustment before the vehicle is passed to a user (for example, on a bench tester) beforehand, and a value experimentally acquired may be also recorded beforehand.

The calculation of the basic rates of the change RATE [x], RATE1, RATE2 and RATE3 is not necessarily executed only once in the initial stage and may be also repeated at a suitable cycle (for example, every ten thousand km on an odometer and in motor vehicle inspection). [0063]
Estimation learning control is classified into estimation learning control in idling and estimation learning control in running. [0064]
The estimation learning control in idling is executed when the vehicle idles. As shown in Fig. 7, each KBUK is initially 1.000. Suppose that from this state, KBUK of the first area 70a which is the idle area decreases by a threshold 0.100 and varies to 0.900. At this time, values of all KBUK [2] to KBUK [10] of the second area 70b to the tenth area 70j are corrected based upon the current area variation V of KBUK [1] (in this case, -0.100) and the basic rates of a change RATE [2] to RATE [10]. For example, KBUK [4] is updated to 0.992 as KBUKNEW [4] acquired by calculating KBUK0LD [4] + V * RATE [4] = 1.000 + (-0.100) x 0.080 based upon its initial value 1.000. Subscripts "OLD" and "NEW" denote before and after updating. As for the other areas, updated values are also acquired by the similar calculation. [0065]
As disturbance is large in the idle area, it is suitable to precisely correct all the other areas based

upon the basic rates of the change RATE as described above. [0066]
Next, the estimation learning control in running will be described. The estimation learning control in running is executed in running. [0067]
As shown in Pig. 8, suppose that KBUK [6] of the sixth area 70f decreases by the threshold 0.100 from a state of 0.988 while the vehicle is run and varies to 0.888. At this time, each KBUK in the upper stage, the middle stage and the lower stage is corrected based upon the current area variation V (in this case, -0.100), the average of the upper stage RATEl, the average of the middle stage RATE2 and the average of the lower stage RATE3 or the correction quantity of each KBUK is limited. In the limit of correction quantity, quantity that varies by correction shall not exceed the current area variation V.
[OOfiR]
As shown in Fig. 9, for example, KBUK [4] in the upper stage is updated to 0.936 as KBUKj*EW [4] acquired by calculating KBUK0LD [4] + V * RATEl/RATE [6] = 0.992 + (-0.100) * 0.067/0.12 based upon its initial value 0.992 using the average of the upper stage RATEl. In this case, quantity that varies by correction is 0.056 acquired by calculating 0.992 - 0.936 and as the value is smaller than the current area variation V, the limit is not required. Updated values of the other areas are also acquired by the similar calculation. As for KBUK [4], RATE [4] may be also

used in place of the average of the upper stage RATE1. The processing of KBUK [4], KBUK [7] and KBUK [10] in the upper stage is simplified by using the average of the upper stage RATE1. [0069]
Next, as for KBUK [3] in the middle stage, the similar correction to KBUK [4] is basically made, however, as the basic current area variation V is multiplied by RATE2/RATE [6] in a process of the calculation, quantity that varies by correction when RATE2/RATE [6] > 1 is equal to or exceeds the current area variation V. Therefore, at that time, limitation based upon the current area variation V is made. In this case, as RATE2/RATE [6] = 0.12/0.12 > 1, limitation based upon the current area variation V is made and 0.884 as KBUKNEw [3] is acquired by calculating KBUK0LD [3] + V = 0.984 - 0.100. As for KBUK [9] in the middle stage, the similar calculation is also made. [0070]
The case of the lower stage is also similar to the middle stage and for example, as for KBUK [2], as RATE3/RATE [6] = 0.44/0.12 > 1, limitation based upon the current area variation V is made and 0.868 as KBUKNEW [2] is acquired by calculating KBUKOLD [2] + V = 0.968 - 0.100. As for KBUK [5] and KBUK [8], the similar calculation is also made. [0071]
As described above, as in the estimation learning control in running, disturbance in running seldom occurs,

simple calculation has only to be executed and simplification is attempted using the average of the upper stage RATE1, the average of the middle stage RATE2 and the average of the lower stage RATE3 and by limitation based upon current area variation V,
[0072]
Estimated correction is estimation to the end and it is desirable that excessive correction is prevented. Then, KBUK is prevented from being excessively corrected by limiting based upon current area variation V. It is suitable to set a limiting value to current area variation V and in addition, processing is simple.
[0073]
As described above, according to the fuel injection system 10 of the engine in this embodiment, when the operational status of the engine is sectioned into ten areas and KBUK of one area is updated by predetermined quant]ty, KBOKs of the other areas nan be updated to a suitable value as promptly as possible by correcting KBUKs of the other areas by estimation according to a trend of the variation. Therefore, for example, immediately after transition to running in which the throttle angle Th is increased when the vehicle enters a highway after running in a state in which the throttle angle Th is small in a town, KBUK of a corresponding control parameter is also substantially a suitable value and the ideal air-fuel ratio is acquired soon.
[0074]

Next, the second control method executed by the controller 14 will be described. In the second and third control methods, the same reference numeral and the same name are allocated to the same component and the same process as those in the first control method and their detailed description is omitted. In the second control method, the controller 14 refers to the second map 80. [0075]
As shown in Fig. 10, the second map 80 is set based upon the engine speed Ne and the throttle angle Th as the first map 40 and its external frame is set to the same range. Areas 82a (an idle area), 82b, 82c, 82e, 82f, 82h and 82i in the second map 80 are set to be similar to the areas 70a, 70b, 70c, 70e, 70f, 70h and 70i in the first map 40 and an area 82d in the second map 80 is set to an area which has a larger throttle angle Th than the corresponding area in the first map 40 and in which the three areas 70d, 70g and 70j on the upside in the graph are integrated. To clarify correspondence with each area in the first map 40, areas 82g and 82j are omitted in the second map 80. [0076]
In the second map 80, in the areas 82a, 82b, 82c, 82e, 82f, 82h and 82i, the same control as that in the areas 70a, 70b, 70c, 70e, 70f, 70h and 70i in the first map 40 is executed. [0077]
In the area 82d on the upside, a representative area 84 in calculation is provided substantially in the center

and slightly on the upside and parameters set in the representative area 84 are handled as those of the whole area 82d. The representative area 84 is in the shape of a similar rectangle having slightly larger width than that of each area 82e, 82f and having moderate height so as to simplify setting. When the engine speed of the representative area 84 is set to an range including intermediate engine speed Nee in a region in which the engine speed Ne is used (from engine idle speed Nel to critical engine speed Ne2), a frequency of updation increases and it is favorable. Further, it is suitable that the width in the engine speed Ne of the representative area 84 is approximately 4000 to 8000 rpm and it is suitable that the height in the throttle angle Th is
approximately 10 to 40" (under a condition that 02 feedback
is performed).
[0078]
The representative area 84 is an area substantially equal to the area 70g and a parameter equivalent to KBUK [7] corresponding to the area 70g is also used for the area 82d. [0079]
The representative area 84 is a location which has a large throttle angle Th on which aged deterioration hardly has an effect and in which the variation of taken air is stable and stable precise control is enabled by learning the variation of air density in such an area. Parameters in the representative area 84 initially act as

deterioration/environment correction factors (factors for correcting long-term variation such as aged deterioration in the internal combustion engine and short-term variation such as the variation of atmospheric pressure) and are reflected in the whole area 82d twice or later.
[0080]
According to results of experiments by these inventors, in an area having a large throttle angle Th such as the area 82d, left and right parts (that is, a part in which the engine speed Ne is low and a part in which it is high} are hardly used, compared with a central part frequently used. Therefore, parameters are frequently updated in the central part, while parameters are almost unchanged in the left and right parts and convergence upon appropriate values may be delayed, however, parameters are integrally updated in the area 82d by integrating locations having a large throttle angle Th into one area 82d as in the second map 80 and can be promptly set to appropriate values. As the area 82d is one area, control is made based upon the same parameters even if the engine speed Ne varies from low speed to high speed in the area 82d and a useless change of a state hardly occurs.
[0081]
Further, as parameters in the representative area 84 in the central part frequently used represent those of the whole area 82d, they are frequently updated and learning control is enabled. Furthermore, as the number of the areas is smaller than that in the first map 40, a procedure

for control is simplified, a load of control is decreased, and the storage capacity of parameters is reduced.
[0082]
According to a condition of design that CPU has margin for a load of calculation, the number of areas may be also further increased. At this time, it is desirable that the area 82d having the large throttle angle Th is left as it is and the areas 82c, 82f and 82i in which the throttle angle Th is middle are divided in two maximum by a virtual line 86. In this case, it is desirable that the straight line 66 is slightly lowered and in the area in which the throttle angle Th is smaller in its axial direction, the width of the area in an axial direction of the throttle angle Th is reduced.
[0083]
As described above, according to the second control method, the side on which the throttle angle Th is the largest is set to one area 82d which is not related to the engine speed Ne and the side on which the throttle angle Th is the smallest is set to the plural areas 82a, 82b, 82e and 82h according to the engine speed Ne in the second map 80 .
[0084]
It is reasonable that as there is difference in a used frequency based upon the engine speed Ne, the side on which the throttle angle Th is the largest is integrated into one area. In the meantime, the side on which the throttle angle Th is the smallest is set to the plural

areas according to the engine speed Ne and more precise control is enabled. A location in which the throttle angle Th is middle has only to be divided into suitable areas according to a condition of design and in the map 80, the location is divided into the three areas 82c, 82f and 82i. [0085]
In one area 82d set on the side on which the throttle angle Th is the largest, the representative area 84 is provided and a learned correction factor can be simply and precisely applied to the whole one area by using the learned correction factor acquired in the representative area 84 for that for the whole one area. [0086]
Next, the third control method executed by the controller 14 will be described. In the third control method, the controller 14 refers to the third map 90. [0087]
As shown in Fig. 11, the third map 90 is set based upon the engine speed Ne and the throttle angle Th as in the first map 40 and its external frame is set to the same range. [0088]
An area 92a related to idling (an idle area) in the third map 90 is set to be similar to the area 70a in the first map 40. An area 92b in which the throttle angle Th is middle and small (a middle/small throttle angle area) in the third map 90 is an area acquired by integrating the areas 70b, 70c, 70e, 70f, 70h and 70i in the first map 40

and similarly, an area 92c in which the throttle angle Th is large (a large throttle angle area) is an area acquired by integrating the areas 70d, 70g and 70j . As described above, in the third map 90, only three areas 92a to 92c are provided. The area 92c is equivalent to the area 82d in the second map 8 0 and the same representative area 94 as the representative area 84 is provided. In the area 92a in the third map 90, the same control as the control in the area 70a in the first map 40 is executed and in the area 92c, the same control as the control in the area 82d in the second map 80 is executed. [0089]
In the third control method, parameters KAD [1], KAD [2] and KAD [3] (hereinafter also representatively called KAD) respectively equivalent to KBUK are calculated in connection with the areas 92a, 92b and 92c. A reference value of KAD is 1.0. KAD is properly updated like KBUK, a total correct ion factor KT is pal nil ated using the following expression (3), corrected fuel injection quantity Tl is calculated using the above-mentioned expression (2), and the acquired corrected fuel injection quantity is supplied to the fuel injection time calculating unit 50.
KT - K02 x KTW * KAD * KBUR - KALT (3)
[0090]
KAD [1] of the area 92a related to an idle condition is acquired by subtracting a mean value of K02 at that time from a target K02 in the idle condition like KBUK [1] of the area 70a. KAD [3] of the area 92c in which the

throttle angle Th is large is calculated based upon the representative area 94 and the substantially same value as the value of KBUK [7] of the area 70g is acquired. KAD [2] of the area 92b in which the throttle angle Th is middle and small is calculated based upon KAD [1] and KAD [3] using the following expression (4).
KAD [2] Ā«- ((KAD [1] - 1.0) * Kc + 1.0) * KAD [3]
(4) [0091]
In this case, the parameter Kc is a value acquired referring to a table 100 shown in Fig. 12. In the table 100, the throttle angle Th of the area 92b is sorted in seven levels and the engine speed Ne is sorted in five levels (for example, every 1000 rpm) , As for the parameter Kc, left and upper fields are blank according to a shape of the area 92b, however, needless to say, data may be also recorded in this part. [00921
In the expression (4), first, a variation of KAD [1] for the reference value 1.0 is calculated, the calculated variation is weighted by multiplying the variation by the parameter Kc, and further, after the reference value 1.0 is added to the weighted variation, the value is multiplied by KAD [3] . Therefore, an effect of KAD [1] according to sorting is applied to KAD [3] and correction is made. An expression for acquiring KAD [2] is not limited to the expression (4) and an appropriate another method based upon KAD [1] and KAD [3] may be also used.

[0093]
Divergence due to these effect can be absorbed by-learning a variation of KAD [3] as a variation by a change due to atmospheric pressure or the deterioration of an engine and others and reflecting the variation in KAD [1].
[0094]
As described above, according to the third control method, the third map 90 includes the area 92a as the idle area corresponding to idling, the area 92c as the large throttle angle area on the side on which the throttle angle Th is the largest and the area 92b as the middle/small throttle angle area except the areas 92a and 92c, and KAD
[2] which is a learned correction factor of the area 92b is calculated based upon KAD [1] of the area 92a and KAD [3] of the area 92c. As described above, when the three areas 92a to 92c are used, the number of areas is reduced enough and storage capacity for storing parameters such as a
1 earned correct ion factor can be reduced. As the number of parameters is reduced, a load in computing onto CPU decreases and a procedure for processing is simplified.
[0095]
In this embodiment, an electronic throttle valve system in which the throttle valve is opened and closed by the actuator has been described, however, the invention can be also applied to a mechanical throttle valve system in which the throttle valve is opened and closed by wire. Further, in place of the water temperature sensor, an oil temperature sensor for detecting the temperature of

lubricating oil of the engine may be also used. [0096]
The fuel injection system of the internal combustion engine according to the invention is not limited to the above-mentioned embodiment and it need scarcely be said that various configurations may be adopted without deviating from the subject matter of the invention. [Brief Description of the Drawings] [0097]
[Fig. 1] Fig. 1 is a schematic drawing showing an engine system.
[Fig. 2] Fig. 2 is a block diagram showing a controller. [Fig. 3] Fig. 3 shows plural areas in a first map where basic fuel injection quantity is recorded.
[Fig. 4] Fig. 4 schematically shows a degree of each error with ideal air-fuel ratio when no feedback is made. [Fig. 5] Fig. 5 is a time chart showing the transition of variables K02 and KBUK.
[Fig. 6] Fig. 6 is a table showing a basic rate of a change RATE every area.
[Fig. 7] Fig. 7 is a table showing a change of KBUK in an idle area.
[Fig. 8] Fig. 8 is a table showing the updates of KBUKs by estimation learning control in idling.
[Fig. 9] Fig. 9 is a table showing the updates of KBUKs by estimation learning control in running.
[Fig. 10] Fig. 10 shows plural areas in a second map where basic fuel injection quantity is recorded.

[Fig. 11] Fig. 11 shows plural areas in a third map where basic fuel injection quantity is recorded.
[Fig. 12] Fig. 12 is a table in which a parameter Kc is recorded.
[Description of Reference Numerals and Letters]
[0098]
10 ... Fuel injection system
11 ... Engine system
12 ... Engine
14 ... Controller
16 ... Fuel injection
18 ... Ignition plug
20 ... Throttle valve
24 . . . 02 sensor
26 ... Acceleration sensor
2 8 ... Crank
30 ... Revolution speed sensor
40, fin, 80, 90 ... Map
42 ... Basic fuel injection quantity calculating unit
44 ... Feedback unit
46 ... Correction quantity recording unit
48 ... Correcting unit
50 ... Fuel injection time calculating unit
70a to 70j, 82a to 82f, 82h, 82i, 92a to 92c ... Area
Ne ... Engine speed
Th ... Throttle angle


[Document Name] Scope of Claims [Claim 1]
A fuel injection system of an internal combustion engine comprising:
basic injection quantity calculating means that calculates basic fuel injection quantity based upon a throttle angle and engine speed, referring to a basic fuel injection map based upon the throttle angle of a throttle valve provided to an intake system of the internal combustion engine and the engine speed of the internal combustion engine;
feedback correction factor calculating means that calculates a feedback correction factor for feedback-controlling fuel injection at a predetermined cycle based upon an output signal output from an 03 sensor provided to an exhaust system;
final fuel injection quantity calculating means that determines final fuel injection quantity by multiplying the basic fuel injection quantity by the feedback correction factor to approach target air-fuel ratio; and
feedback learned correction factor storing means that stores the feedback correction factor as a learned correction factor in a non-volatile storage at predetermined timing,
wherein: the feedback learned correction factor storing means stores the calculated learned correction factor every corresponding area sectioned into plural areas beforehand according to operational status in the basic

fuel injection map; and
in the area in which the throttle angle is smaller of the plural areas, the height of the area in an axial direction of the throttle angle is made smaller in comparison in locations in which the engine speed is the same in the basic fuel injection map. [Claim 2]
The fuel injection system of the internal combustion engine according to Claim 1,
wherein: the side on which the throttle angle is the largest out of the plurality of areas is set to one area independent of the engine speed; and
the side on which the throttle angle is the smallest is set to a plurality of areas according to the engine speed. [Claim 3]
The fuel injection system of the internal combustion engine according to Claim 2,
wherein: a representative area is provided to one area set on the side on which the throttle angle is the largest; and
the learned correction factor acquired in relation to the representative area is reflected as a learned correction factor of the whole one area. [Claim 4]
The fuel injection system of the internal combustion engine according to Claim 1,
wherein: the area includes an idle area corresponding

to idling, a large throttle angle area on the side on which the throttle angle is the largest and a middle/small throttle angle area except the idle area and the large throttle angle area; and
a learned correction factor of the middle/small throttle angle area is calculated based upon a learned correction factor of the idle area and a learned correction factor of the large throttle angle area. [Claim 5]
A fuel injection system of an internal combustion engine comprising:
basic injection quantity calculating means that calculates basic fuel injection quantity based upon a throttle angle and engine speed, referring to a basic fuel injection map based upon the throttle angle of a throttle valve provided to an intake system of the internal combustion engine and the engine speed of the internal combustion engine ,-
feedback correction factor calculating means that calculates a feedback correction factor for feedback-controlling fuel injection at a predetermined cycle based upon an output signal output from an 02 sensor provided to an exhaust system;
final fuel injection quantity calculating means that determines final fuel injection quantity by multiplying the basic fuel injection quantity by the feedback correction factor to approach target air-fuel ratio; and
feedback learned correction factor storing means that

stores the feedback correction factor as a learned correction factor in a non-volatile storage at predetermined timing and in which the final fuel injection quantity calculating means calculates final fuel injection quantity using the learned correction factor in operational status in which no feedback control based upon the output signal from the 02 sensor is made,
wherein the fuel injection system includes estimation-correcting means that holds a basic rate of a change of the learned correction factor every plural areas or every some adjacent areas in a predetermined recording unit and corrects the learned correction factor of at least one of the other areas based upon a current area variation and the corresponding basic rate of a change when the current area variation for a reference value of the learned correction factor in a current area is equal to or exceeds predetermined quantity. [Claim fi]
The fuel injection system of the internal combustion engine according to Claim 5, wherein in the estimation-correcting means, predetermined limitation is provided to the correction quantity of the other area. [Claim 7]
The fuel injection system of the internal combustion engine according to Claim 6, wherein the limitation is equivalent to the current area variation. [Claim 8]
The fuel injection system of the internal combustion

engine according to Claim 5 or 6, wherein the plural areas include an independent idling area corresponding to idling. [Claim 9]
The fuel injection system of the internal combustion engine according to Claim 8, wherein when the current area variation is equal to or exceeds predetermined quantity in idling of a vehicle, the correction factors of all the areas except the idling area are estimation-corrected based upon a variation of the learned correction factor and the basic rate of a change.


Documents:

http://ipindiaonline.gov.in/patentsearch/GrantedSearch/viewdoc.aspx?id=wpva16og/d0v7HezK7z8cQ==&loc=egcICQiyoj82NGgGrC5ChA==


Patent Number 268565
Indian Patent Application Number 210/CHE/2009
PG Journal Number 36/2015
Publication Date 04-Sep-2015
Grant Date 03-Sep-2015
Date of Filing 29-Jan-2009
Name of Patentee HONDA MOTOR CO., LTD.
Applicant Address 1-1, MINAMI-AOYAMA 2-CHOMEMINATO-KUTOKYO 107-8556.
Inventors:
# Inventor's Name Inventor's Address
1 NISHIZAWA, KENICHI, C/O HONDA R&D CO; LTD. 4-1, CHUO 1-CHOME, WAKO-SHI, SAITAMA 351-0193
2 TANAKA, HIROSHI, C/O HONDA R&D CO; LTD. 4-1, CHUO 1-CHOME, WAKO-SHI, SAITAMA 351-0193
3 ONISHI, KENTA, C/O HONDA R&D CO; LTD. 4-1, CHUO 1-CHOME, WAKO-SHI, SAITAMA 351-0193
4 TAKANO, YUKI, C/O HONDA R&D CO; LTD. 4-1, CHUO 1-CHOME WAKO-SHI SAITAMA 351-0193.
5 AKAMATSU, SHUNJI, C/O HONDA R&D CO; LTD. 4-1, CHUO 1-CHOME, WAKO-SHI, SAITAMA 351-0193
6 SHIMADA, NOBUHIRO, C/O HONDA R&D CO; LTD. 4-1, CHUO 1-CHOME, WAKO-SHI, SAITAMA 351-0193
PCT International Classification Number F02M63/00
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 2008-141991 2008-05-30 Japan
2 2008-021848 2008-01-31 Japan