JP3685884B2 - Vehicle driving force control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a driving force control device for a vehicle that reduces the driving force of a driving wheel and suppresses the excessive slip when an excessive slip of the driving wheel is detected.
[0002]
[Prior art]
A so-called traction control device for preventing excessive slip of the drive wheel includes slip ratio calculation means for calculating the slip ratio of the drive wheel, and drive force reduction level determination means for determining the drive force reduction level according to the slip ratio of the drive wheel. And a driving force reducing means for reducing the driving force of the driving wheel in accordance with the driving force reduction level. The slip ratio of the driving wheel is calculated based on the driving wheel speed detected by the driving wheel speed sensor and the driven wheel speed detected by the driven wheel speed sensor.
[0003]
By the way, when the vehicle travels on a rough road and a large body vibration occurs, or when noise acts on the output of the drive wheel speed sensor, the detected drive wheel speed is slightly fluctuated. The apparent driving wheel speed may increase. When the apparent drive wheel speed increases in this way, the slip ratio of the drive wheel calculated by the traction control device based on the drive wheel speed increases, unlike the actual one, and precise traction control becomes difficult.
[0004]
Conventionally, this has been dealt with by filtering the detected driving wheel speed or adjusting the weighting factor for control.
[0005]
[Problems to be solved by the invention]
However, when the above conventional means is employed, the actual driving wheel speed is reduced when an excessive slip occurs due to vehicle start, acceleration, shift change, etc., or when an excessive slip occurs due to a sudden change in the road surface friction coefficient. It is determined that the increase is an increase in the apparent driving wheel speed described above, and the response of the driving force reduction of the driving wheel may be reduced.
[0006]
The present invention has been made in view of the above-described circumstances, and reliably detects actual fluctuations in the drive wheel speed while eliminating the influence of apparent fluctuations in the drive wheel speed, thereby accurately preventing excessive slip of the drive wheel. For the purpose.
[0007]
[Means for Solving the Problems]
In the first aspect of the present invention, the driving force reduction level determining means determines the driving force reduction level according to the slip ratio of the driving wheel calculated by the slip ratio calculating means, and the driving force is reduced according to the driving force reduction level. The reducing means reduces the driving force of the driving wheel. At this time, a plurality of driving wheel speeds sampled with time intervals are stored in the first storage means, and the stored data are added by the first addition means, and sampled with time intervals. A plurality of driving wheel speeds, which are sampled on average faster than the plurality of driving wheel speeds stored in the first storage means, are stored in the second storage means, and the stored data Are added by the second adding means. The subtraction means subtracts the addition value obtained by the second addition means from the addition value obtained by the first addition means, and the slip level determination means determines the slip level of the drive wheel based on the obtained subtraction value. Based on the determined slip level, the driving force reduction level correcting means corrects the driving force reduction level.
[0008]
When the slip level is determined, the addition value obtained by adding the plurality of data stored in the first storage means and the addition value obtained by adding the plurality of data stored in the second storage means are used. It is possible to eliminate the influence of the instantaneous fluctuation of the driving wheel speed, which is short in time, and to calculate the deviation between the data of the first storage means and the data of the second storage means having a time difference, so that the driving wheels The actual fluctuation in speed can be accurately detected.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described based on examples of the present invention shown in the accompanying drawings.
[0010]
1 to 10 show an embodiment of the present invention. FIG. 1 is an overall configuration diagram of a vehicle equipped with a driving force control device, FIG. 2 is a block diagram of a control system, and FIG. 3 is a flowchart of a main routine. 4 is an explanatory diagram of sampling of the driving wheel speed, FIG. 5 is an explanatory diagram of the ring buffer, FIG. 6 is an explanatory diagram of the operation of the ring buffer, FIG. 7 is a flowchart of the driving wheel speed addition processing routine, and FIG. FIG. 9 is an explanatory diagram of the action of determining the slip level, and FIG. 10 is an explanatory diagram of the action of reducing the engine output.
[0011]
As shown in FIG. 1, this vehicle is a front wheel drive vehicle, and a pair of left and right drive wheels W _FL and W _{FR to} which the driving force of the four-cylinder engine E is transmitted via an automatic transmission M and accompanying traveling. And a pair of left and right driven wheels W _RL and W _RR that rotate. The left and right driving wheels W _FL and W _FR are provided with driving wheel speed sensors S ₁ and S ₁ for detecting the driving wheel speed, and the left and right driven wheels W _RL and W _RR are driven wheels for detecting the driven wheel speed. Speed sensors S ₂ and S ₂ are provided.
[0012]
The electronic control unit U to which signals from the drive wheel speed sensors S ₁ and S ₁ and the driven wheel speed sensors S ₂ and S ₂ are input is used to control the engine E to suppress excessive slip of the drive wheels W _FL and W _FR . The output of the engine E is controlled by controlling the opening of the throttle valve 2 interposed in the intake passage 1, the ignition timing of the spark plug 3 of the engine E, and the fuel injection amount of the fuel injection valve 4 of the engine E. To reduce.
[0013]
As shown in FIG. 2, the electronic control unit U includes a slip ratio calculating means M1, a driving force reduction level determining means M2, a driving force reducing means M3, a first storage means M4, a second storage means M5, First addition means M6, second addition means M7, subtraction means M8, slip level determination means M9, and driving force reduction level correction means M10 are provided.
[0014]
Next, the outline of the operation of the embodiment of the present invention will be described with reference to the block diagram of FIG. 2 and the flowchart of the main routine of FIG.
[0015]
First, in step S1, the driving wheel speed detected by the driving wheel speed sensors S ₁ and S ₁ is stored in the ring buffer, and the stored data is updated for each loop. As will be described in detail later, the ring buffer includes a window A constituting the first storage means M4 and a window B constituting the second storage means M5, and a plurality of data stored in the window A in step S2 and The plurality of data stored in the window B are added by the first addition means M6 and the second addition means M7, respectively. In the next step S3, the addition value of the data stored in the window B is subtracted by the subtraction means M8 from the addition value of the data stored in the window A, and the deviation is calculated in step S4. Based on this, the slip levels of the drive wheels W _FL and W _FR are determined.
[0016]
In step S5, the slip ratio calculating means M1 drives the driving wheel W based on the driving wheel speed detected by the driving wheel speed sensors S ₁ and S ₁ and the driven wheel speed detected by the driven wheel speed sensors S ₂ and S _2. The slip ratios of _FL and _WFR are calculated, and in the subsequent step S6, the driving force reduction level determination means M2 determines eight levels of engine output reduction levels from “0” to “7” according to the slip ratio. If the slip level is level 2 (highest level) in steps S7 to S10, the driving force reduction level correction means M10 increases the engine output reduction level by two steps, and if the slip level is level 1 (intermediate level), the engine The output reduction level is increased by one step. If the slip level is level 0 (minimum level), the engine output reduction level is left as it is.
[0017]
When the corrected engine output reduction level is determined in this way, the driving means of the spark plugs 3... And the fuel injection valves 4. _FL, to suppress the excess slip of W _FR.
[0018]
Hereinafter, the contents of each step of the flowchart of the main routine described above will be described in further detail. Since the process related to the right drive wheel speed and the process related to the left drive wheel are substantially the same, the process related to the right drive wheel speed will be described below as a representative.
[0019]
First, the contents of step S1 in the flowchart of FIG. 3 will be described. As shown in FIG. 5, the ring buffer is composed of a window A and a window B. The window A includes 6-byte buffers # VWRBF1 to # VWRBF6, and the window B includes 6 bytes # VWRBF7 to # VWRBF12. With a buffer. The pointer VWPOT represents the difference from the start address of each window A, B to 00h to the address of the buffer storing the oldest data in the windows A, B.
[0020]
As shown in FIG. 4, the driving wheel speed LVWFR is sampled at intervals of 30 ms, for example, and the latest data is stored in window A, and data 30 ms older than that is stored in window B. This will be further described with reference to FIG. 6. First, the initial value of the pointer VWPOT is set to 00h, and the buffer data corresponding to # VWRBF1 + VWPOT is moved to the buffer corresponding to # VWRBF6 + VWPOT. As a result, new driving wheel speed LVWFR data is stored in a buffer corresponding to # VWRBF1 + VWPOT which has become empty. The above process is repeated while incrementing VWPOT, and when VWPOT reaches # 06h, it is reset to # 00h.
[0021]
In this way, each data stored in the six buffers # VWRBF1 to # VWRBF6 of window A is sequentially moved to # VWRBF7 to # VWRBF12 to the corresponding six buffers of window B, so that window A Compared with the data of window B, the data of is relatively new by 30 ms which is the sampling interval.
[0022]
Next, the contents of steps S2 and S3 in the flowchart of FIG. 3 will be described. In the flowchart of FIG. 7, the addition value GA (n) of the data stored in the six buffers # VWRBF1 to # VWRBF6 of the window A in steps S11 and S12 is calculated using the previous value GA (n-1). To do. Specifically, in step S11, the old data of window A (data moved to window B) is subtracted from the previous value GA (n-1) of the addition value, and further stored in current window A in step S12. The added value GA (n) for this time is calculated by adding the obtained data. Similarly, the addition value GB (n) of the data stored in the six buffers # VWRBF7 to # VWRBF12 of the window B in steps S13 and S14 is calculated using the previous value GB (n-1). Specifically, in step S13, the old data of window B (data deleted from window B) is subtracted from the previous value GB (n-1) of the addition value, and in step S14, the current window A is transferred to window B. The added value GB (n) this time is calculated by adding the obtained data.
[0023]
When the addition value GA (n) of window A and the addition value GB (n) of window B are calculated in this way, the addition value GB (n) is subtracted from the addition value GA (n) to obtain the deviation GN ( n) is calculated. The large deviation GN (n) means that the data of the window A is larger than the data of the window B older than that, and thereby the driving wheel speed increases and a large slip occurs. Can be determined.
[0024]
Next, the contents of step S4 in the flowchart of FIG. 3 will be described. In the flowchart of FIG. 8, if the deviation GN is greater than or equal to the first reference value R ₁ in step S21, the slip level of the drive wheels is set to level 2 (large slip) in step S22. If the deviation GN is less than the first reference value R _{1 and} greater than or equal to the second reference value R ₂ (R ₁ > R ₂ ) in steps S21 and S23, the drive wheel slip level is set to level 1 (medium slip) in step S24. To do. Also if the deviation GN is smaller than the second reference value R ₂ at step S23, it sets the level 0 (small slip) slip level at step S25. Incidentally, the slip level is determined respectively for the right driving wheel W _FR and the left driven wheels W _FL, larger one of them is selected as the final slip level. FIG. 9 shows an example of the slip level determined by increasing / decreasing the deviation GN.
[0025]
Next, the contents of steps S5 and S6 in the flowchart of FIG. 3 will be described. The determination of the slip state of the driving wheel is performed in general traction control, and is performed by comparing the driving wheel slip ratio calculated based on the driving wheel speed and the driven wheel speed with the target slip ratio. . Then, eight stages of engine output reduction levels from level 0 to level 7 are determined according to the deviation between the drive wheel slip ratio and the target slip ratio.
[0026]
FIG. 10 shows an example of the engine output reduction level. At the engine output reduction level 0 where the deviation between the drive wheel slip ratio and the target slip ratio is small, the engine output reduction control is not performed, and the deviation increases and the engine output decreases. When the reduction level 1 is reached, ignition timing control (ignition retarding control) is executed, and when the deviation further increases and the engine output reduction level 2 is reached, the air-fuel ratios of all the cylinders are made lean. In the engine output reduction level 3 to level engine output reduction 7 where the deviation further increases, the air-fuel ratio leaning and fuel cut are used in combination, and in the engine output reduction level 3, the ½ amount fuel cut of the # 1 cylinder, engine output At the reduction level 4, the entire fuel cut of the # 1 cylinder is performed, at the engine output reduction level 5, the fuel cut of the # 1 and # 2 cylinders is performed, and at the engine output reduction level 6, the fuel cut of the # 1, # 2, and # 3 cylinders is performed. Then, at the engine output reduction level 7 where the deviation becomes the maximum, the fuel cut of all cylinders is performed.
[0027]
When the engine output reduction control described above is performed, if the slip level determined in the flowchart of FIG. 8 is level 2 (large slip), the engine output reduction level determined in step S6 is increased by two stages. For example, if the original engine output reduction level is 3, the engine output reduction level is increased by two stages to 5 so that the engine output is further reduced to effectively prevent excessive slip of the drive wheels. can do.
[0028]
If the slip level is level 1 (medium slip), the engine output reduction level determined in step S6 is increased by one step. If the slip level is level 0 (small slip), the engine output reduction determined in step S6. Adopt the level as it is. In addition, when the limit level (all-cylinder fuel cut level 7) is reached by increasing the engine output reduction level, the engine output is not further reduced.
[0029]
In this way, fine driving wheel slip control can be performed by correcting the engine output reduction level according to the slip level. In addition, when the slip level is determined, the addition value GA obtained by adding the data stored in the six buffers # VWRBF1 to # VWRBF6 of the window A and the six buffers # VWRBF7 to # VWRBF12 of the window B are stored. Since the added value GB is calculated by adding the obtained data, it is possible to eliminate the influence of noise and disturbance on the driving wheel speed sensor S ₁ , S ₁ output due to fluctuations in the driving wheel speed due to rough road driving, By calculating the deviation between the data of the window A and the data of the window B having a time difference, the actual fluctuation tendency of the driving wheel speed, that is, the slip level of the driving wheel is accurately detected, and the responsiveness is lowered. And driving force can be reduced.
[0030]
As mentioned above, although the Example of this invention was explained in full detail, this invention can perform a various design change in the range which does not deviate from the summary.
[0031]
For example, a throttle valve driving means can be added to the driving force reducing means M3 shown in FIG. As an example, in FIG. 10, engine output reduction control is not performed at engine output reduction level 0, ignition timing control (ignition retarded control) is performed at engine output reduction level 1, and throttle opening is performed at engine output reduction level 2. By performing the control, the throttle opening control, the lean air-fuel ratio and the fuel cut can be used together at the engine output reduction level 3 to 6, and the fuel cut of all cylinders can be performed at the engine output reduction level 7. Further, the driving force reducing means M3 is not limited to the one that reduces the engine output, but may be one that brakes the driving wheels W _FL and W _FR to reduce the driving force.
[0032]
【The invention's effect】
As described above, according to the first aspect of the present invention, when the slip level is determined, an addition value obtained by adding a plurality of data stored in the first storage means and the second storage means are stored. Further, since the added value obtained by adding a plurality of data is used, it is possible to eliminate the influence of the fluctuation in the apparent driving wheel speed having a short duration due to the vehicle body vibration or noise. Further, by calculating the deviation between the data of the first storage means and the data of the second storage means having a time difference, the actual fluctuation of the drive wheel speed caused by the time difference can be accurately detected as the slip level. Since the driving force reduction level is corrected based on the slip level, when the driving wheel actually slips, the driving force can be reduced without delay and the excessive slip of the driving wheel can be effectively suppressed.
[Brief description of the drawings]
FIG. 1 is an overall configuration diagram of a vehicle equipped with a driving force control apparatus. FIG. 2 is a block diagram of a control system. FIG. 3 is a flowchart of a main routine. Fig. 6 is an explanatory diagram of the buffer. Fig. 6 is an operation diagram of the ring buffer. Fig. 7 is a flowchart of a driving wheel speed addition processing routine. Fig. 8 is a flowchart of a slip level determination routine. ] Explanation of engine output reduction [Explanation of symbols]
M1 Driving wheel slip ratio calculation means M2 Driving force reduction level determination means M3 Driving force reduction means M4 First storage means M5 Second storage means M6 First addition means M7 Second addition means M8 Subtraction means M9 Slip level determination means M10 Driving force Reduction level correction means W _FL drive wheel W _FR drive wheel

Claims (1)

A slip ratio calculating means (M1) for calculating a slip ratio of the driving wheels (W _FL , W _FR ), a driving force reduction level determining means (M2) for determining a driving force reduction level according to the slip ratio, and a driving force; In a vehicle driving force control device comprising driving force reduction means (M3) for reducing the driving force of driving wheels (W _FL , W _FR ) according to the reduction level,
First storage means (M4) for storing a plurality of drive wheel speeds sampled at time intervals;
A plurality of driving wheel speeds sampled at time intervals, and a plurality of driving wheel speeds sampled on average faster than a plurality of driving wheel speeds stored in the first storage means (M4). Second storage means (M5) for storing;
First addition means (M6) for adding the drive wheel speed stored in the first storage means (M4);
Second addition means (M7) for adding the drive wheel speed stored in the second storage means (M5);
Subtracting means (M8) for subtracting the added value by (M7) from the added value by the first adding means (M6) to the second adding means;
Slip level determination means (M9) for determining the slip level of the drive wheels (W _FL , W _FR ) based on the subtraction value by the subtraction means (M8);
Driving force reduction level correction means (10) for correcting the driving force reduction level based on a slip level;
A driving force control apparatus for a vehicle, comprising:

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