JP3062757B2 - Drive wheel torque control device for vehicle - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Object of the Invention (1) Industrial application field The present invention relates to a driving slip reference value setting means for setting a driving slip reference value for detecting a slip state of a driving wheel of a vehicle. And a control amount determining means for determining a drive torque reduction control amount for reducing the drive wheel torque when the drive wheel slips beyond the drive slip reference value.

(2) Prior Art Conventionally, such an apparatus is known, for example, from Japanese Patent Publication No. 52-198.

(3) Problems to be Solved by the Invention By the way, in the above-mentioned conventional one, the driving torque of the driving wheels is reduced to obtain the maximum driving force by detecting the slip state of the driving wheels. The limit lateral force generated in the driving wheels increases when the driving force is reduced rather than when the maximum driving force is obtained. Therefore, when the vehicle is steered while the slip state is detected and the drive wheel torque is reduced as described above, the yaw motion requested by the driver is not required if the steering is within the range of the limit lateral force. However, if the vehicle turns beyond the limit lateral force, the yaw motion required by the driver does not occur, and the front engine / front drive (FF) type vehicle tends to understeer, and the front engine / rear Drive (FR) vehicles tend to be austere.

The present invention has been made in view of such circumstances,
An object of the present invention is to provide a drive wheel torque control device for a vehicle capable of realizing a desired yaw motion while suppressing a decrease in effective driving force in consideration of a turning motion state and a slip state.

B. Configuration of the Invention (1) Means for Solving the Problems The invention of claim (1) sets a drive slip reference value for setting a drive slip reference value for detecting a slip state of a drive wheel of a vehicle. Means, and a drive wheel torque control device for a vehicle, comprising: a control amount determining means for determining a drive torque reduction control amount for reducing the drive wheel torque when the drive wheel slips over the drive slip reference value. Turning motion state detection means for detecting an actual turning motion state of the vehicle based on the steering of the driver, turning motion state reference value setting means for setting a turning motion state reference value of the vehicle according to the steering of the driver, The drive slip reference value is corrected based on the actual turning movement state detected by the turning movement state detecting means and the turning movement state reference value set by the turning movement state reference value setting means. Reference value correcting means.

According to a second aspect of the present invention, in addition to the configuration of the first aspect, the turning motion state reference value of the actual turning motion state detected by the turning motion state detecting means is provided. And a correction value setting means for setting a correction value for correcting the drive slip reference value by the reference value correction means based on the deviation calculated by the deviation calculation circuit. Features.

According to a third aspect of the present invention, in addition to the configuration of the second aspect of the present invention, it is possible to determine whether the vehicle is in an over-steering state or an under-steering state, A steering characteristic determining circuit for reflecting a result of the determination to the correction value setting by the correction value setting means;

(2) Operation According to the configuration of the invention of the above-mentioned claim (1), based on the actual turning motion state of the vehicle based on the steering of the driver and the turning motion state reference value according to the steering of the driver. Since the drive slip reference value is corrected and the slip state of the drive wheel is detected based on the corrected drive slip reference value,
Drive while sufficiently considering information on the turning motion state of the vehicle (that is, the actual turning motion state of the vehicle generated based on the driver's steering and the turning motion state reference value set according to the driver's steering). The wheel torque can be controlled to accurately adjust the limit lateral force according to the driver's steering amount at the time of excessive slip, so that both the driving force and the turning motion without promoting unnecessary yaw motion. Can be appropriately controlled.

Further, according to the configuration of the invention of claim (2), the drive slip reference value is corrected by the correction value set based on the deviation of the turning motion state from the turning motion state reference value, so that the driver can Both the driving force and the turning motion are appropriately controlled according to the intended operation situation.

Further, according to the configuration of the invention of claim (3),
The correction value is set by the correction value setting means depending on whether the vehicle is in the over-steering state or the under-steering state, and the driving slip reference value is corrected by the correction value. It is possible to obtain an appropriate vehicle turning behavior by changing the determination condition of the slip state of the drive wheels between when the vehicle is in the understeering state and when the vehicle is in the understeering state.

(3) Embodiment Hereinafter, an embodiment of the present invention will be described with reference to the drawings. First, in FIG.
The drive wheel torque control device applied to the front drive type vehicle includes first and second reference wheels as drive slip reference values for detecting a slip state of the drive wheels of the vehicle, that is, the left and right front wheels Wfl, Wfr in the drive direction. a drive slip reference value setting means 1 for setting speed Vr _1, Vr _2, the driving wheel torque reduction control quantity a corresponding to the slip state when detecting the slip state on the basis of their reference wheel speed Vr _1, Vr ₂ Control amount determining means 2 for determining the vehicle, and yaw rate detecting means 10 as a turning motion detecting means for detecting a turning motion state of the vehicle.
A reference yaw rate setting means 11 as a turning movement state reference value setting means for setting a turning movement state reference value; and the first and second reference values based on signals from the yaw rate detection means 10 and the reference yaw rate setting means 11. Wheel speed Vr
_1, a correction value setting means 5 for setting a correction value B · K to fix Vr _2, the control amount determining unit front wheels Wfl under the control amount A from 2, driving for allowing reduction drive torque Wfr And a wheel torque reducing means 7.

Free rolling wheels of the vehicle, that is, left and right rear wheels in FF type vehicles
Wrl, Wrr are individually provided with speed sensors Srl, Srr, and the wheel speeds detected by these speed sensors Srl, Srr are input to the vehicle speed detector 8 and also to the yaw rate detecting means 10. You. The vehicle speed detector 8 averages both free rolling wheel speeds to obtain a vehicle speed Vv.
The vehicle speed Vv is input to the selection circuit 9, the drive slip reference value setting means 1, the reference yaw rate setting means 11, and the allowable deviation value setting means 4, respectively.

Speed sensors Sfl, Sfr are provided for the left and right front wheels Wfl, Wfr, which are drive wheels.
Are provided separately, and these speed sensors Sfl, Sfr
The wheel speeds detected in step (1) are input to the selection circuit 9, and one of the two drive wheel speeds is selected as the drive wheel speed Vw according to the vehicle speed Vv. That is, when the vehicle speed Vv is at an extremely low speed of, for example, less than 4 km, the lower one of the two drive wheel speeds is selected as the drive wheel speed Vw, and when the vehicle speed Vv is 4 km / h or more, The higher one is selected as the drive wheel speed Vw. The drive wheel speed Vw is input to the control amount determining means 2.

The steering wheel H is provided with a turning angle Ss. The turning angle δ detected at the turning angle Ss is input to the reference yaw rate setting means 11 and the allowable deviation value setting means 4.

In the drive slip reference value setting means 1, first and second reference wheel speeds Vr ₁ and Vr ₂ as drive slip reference values are set according to the vehicle speed Vv as shown in FIG.
First and second reference wheel speeds Vr ₁ and Vr ₂ corresponding to the input vehicle speed Vv are output from the drive slip reference value setting means 1. The first reference wheel speed Vr ₁ is determined according to an allowable slip ratio, and the second reference wheel speed Vr 1
₂ is set to be higher than the first reference wheel speed Vr ₁ as a state in which excessive slip occurs.

The first and second reference wheel speeds Vr ₁ , Vr ₂ obtained by the drive slip reference value setting means 1 are input to the reference value correction means 6, which input the correction values from the correction value setting means 5. The first and second reference wheel speeds Vr ₁ and Vr ₂ are respectively corrected by the correction values B · K as follows.

Vr ₁ = Vr ₁ -BK (1) Vr ₂ = Vr ₂ -BK (2) First and second reference wheel speeds Vr ₁ after being corrected by the reference value correcting means 6 in this way. , Vr ₂ to and the drive wheel speed Vw obtained by the selection circuit 9 are input to the control amount determination means 2. The control amount determining unit 2, the driving wheel torque reduction control quantity A corresponding to the slip state is as shown in the following equation, is determined on the basis of the first and second reference wheel speeds Vr _1, Vr _2.

The control amount A is intended to increase the torque reduction amount higher the value increases, if the (Vw-Vr ₁₎ is negative, namely the driven wheel speed Vw is lower speed than the first reference wheel speed Vr ₁ Is set to A = 0.

The yaw rate detecting means 10 includes a subtraction circuit 14to, a multiplication circuit 15
, A filter 16, a history storage circuit 17 for storing the output history of the multiplication circuit 15, and a history storage circuit 18 for storing the output history of the filter 16. The subtraction circuit 14 has a speed sensor Sr
The free rolling wheel speed obtained by l, Srr is input, and the difference r between the two free rolling wheel speeds is obtained by the subtraction circuit 14. The multiplier 15 multiplies the difference r by a constant proportionality constant d to obtain an approximate value y ′ (= r × d) of the yaw rate.
Here, the proportionality constant d is the tread width of the left and right rear wheels Wrl, Wrr, for example, d = 1.

The filter 16 eliminates the influence of the vibration of the vehicle suspension on the wheel speed, and a recursive filter is used. Here, the fluctuation of the wheel speed due to the resonance with the vibration of the suspension during rough road running is about 10 Hz, and the frequency range of the yaw rate used for controlling the vehicle motion is 0 to 20 Hz.
Therefore, the filter 16 filters the approximate value y 'of the yaw rate with the attenuation range of 2 Hz or more. That is, the filter 16 performs the operation of the following equation (4) when the output value is y '.

y _n = α ₁ · y _n-1 + α ₂ · y _n-2 + α ₃ · y _n-3 + β ₁ ·
y _n ′ + β ₂ yy _{n -1}・ β ₃ yy _{n -3} ′ (4) where α ₁ βα ₃ , β ₁ ββ ₃ are constants determined by experimental results. The subscripts _n '... _N-3 represent the current value, the previous value, etc. of the filtering since the filtering operation is repeated in a constant cycle. Is a history storage circuit
17 is input to the filter 16 and the previous value of the yaw rate y,
The value before the last time is input from the history accumulation circuit 18 to the filter 16.

The reference yaw rate setting means 11 includes a constant selection circuit 19, a history storage circuit 20, an arithmetic circuit 21, and a history storage circuit 22. The constant selection circuit 19 converts the constants a ₁ , a ₂ , b ₁ , b ₂ used for the calculation in the calculation circuit 21 into the vehicle speed V obtained by the vehicle speed detector 8.
The constants a ₁ , a ₂ ,... are determined according to the vehicle speed Vv, for example, as shown in FIG.
The values of b ₁ and b ₂ are input to the arithmetic circuit 21. The history accumulation circuit 20 inputs the history of the steering angle δ detected by the steering angle sensor Ss to the arithmetic circuit 21, and the history accumulation circuit 22
The output value of the arithmetic circuit 21 that is used to input the history of reference yaw rate y _b to the arithmetic circuit 21. Arithmetic circuit 21 is for calculating a history of turning angle δ from the history accumulation circuit 20, a reference yaw rate y _b is currently to be based on a history of the reference yaw rate y _b from the history accumulation circuit 22, the following No. (5)
An operation according to the equation is performed.

and the yaw rate y obtained in _{y b = -a 1 · y bn} -1 -a 2 · y bn-2 + b 1 · δ n-1 + b 2 · δ n-2 ... (5) yaw rate detecting means 10, the reference the reference yaw rate y _b obtained by the yaw rate setting unit 11 is inputted to the deviation value calculating circuit 12, the deviation calculation circuit
12 In the yaw rate y and the reference yaw rate y _b deviation between Dr
(= Y−y _b ) is calculated. The deviation Dr is input to the steering characteristic determination circuit 13.

The steering characteristic determination circuit 13, and the deviation Dr, the reference yaw rate y _b from the reference yaw rate setting unit 11 is inputted, the steering characteristic determination circuit 13, their input D _r, steering based on y _b The characteristics are determined. That is, the steering characteristic determination circuit 13 has predetermined criteria as shown in the following Table (1).
The result determined according to the determination criterion is output from the steering characteristic determination circuit 13.

In Table (1), the symbol O indicates over-steering, and the symbol U indicates under-steering.

The permissible deviation value setting means 4 receives the vehicle speed Vv from the vehicle speed detector 8, the turning angle δ from the turning angle sensor Ss, and a signal indicating the result of the discrimination from the steering characteristic discriminating circuit 13. Then, the permissible deviation value means 4 outputs the reference values y _D and y _c based on the input signals. That is, when the turning angle δ is relatively small, the vehicle speed Vv and the steering characteristic determining circuit
The reference values y _D and y _c are set as shown in FIG. 4 based on the discrimination result of 13, and when the turning angle δ becomes relatively large, the reference values y _D and y _c are set as shown in FIG. Is set larger than the value indicated by. The reference value y _c is set to correspond to a state where the actual steering characteristic from vehicle-specific steering characteristic begins to deviate, the reference value y _D is the deviation between the actual steering characteristic that the vehicle-specific steering characteristic It is set in response to progress to an unacceptable state.

The deviation Dr output from the deviation value calculation circuit 12 is input to the correction value setting means 5 after being converted into an absolute value by the absolute value conversion circuit 23, and the reference values y _D and y _c from the allowable deviation value setting means 4. Is input to the correction value setting means 5.

The correction value setting means 5 includes a correction value calculation circuit 24, a multiplication circuit
25, and the absolute value of the deviation Dr and the reference values y _D , y _c
Is input to the correction value calculation circuit 24. In the correction value calculation circuit 24, the following calculation is performed.

When (| Dr | −y _c ) is negative, B is set to 0.

The value B obtained by this operation is input to the next multiplication circuit 25, and the multiplication circuit 25 multiplies the constant B by the constant K to obtain a correction value B
K is obtained, and this correction value BK is input to the reference value correction means 6. Note that the first and second reference wheel speeds Vr ₁ and Vr ₂ corrected by the correction values BK become equal to the vehicle speed Vv when they become lower than the vehicle speed Vv.

The drive wheel torque control amount A output from the control amount determination unit 2 is input to the drive wheel torque reduction unit 7, and the drive wheel torque reduction unit 7 reduces the drive wheel torque according to the input control amount A. The drive wheel torque reducing means 7 reduces the amount of fuel supplied to the engine, reduces the throttle opening, reduces the transmission of the braking device and the continuously variable transmission, and delays the ignition timing of the engine. For example, one that cuts ignition or the like is used.

Next, the operation of this embodiment will be described. In the front engine / front drive vehicle, the driving force of the front wheels and the limiting lateral force are as shown in FIG. 5, and when the driving lateral force increases, the limiting force decreases. As the force decreases, the limit lateral force increases. Thus, according to the present invention, the reference values for determining the slip state of the drive wheels, that is, the first and second reference wheel speeds Vr ₁ and Vr ₂ are corrected according to the turning motion state of the vehicle, and after the correction. The drive wheel torque reduction control amount A is determined based on the first and second reference vehicle speeds Vr ₁ , Vr _2, and the drive wheel torque reduction means 7 operates based on the drive wheel torque reduction control amount A to drive the drive wheel torque. Is reduced. Therefore, by lowering the reference value for determining the slip state in accordance with the turning motion state according to the steering of the vehicle, the driving force can be reduced and the limit lateral force can be increased, and the driver's steering can be performed. The turning motion corresponding to the amount can be performed within the range of the limit lateral force.

Moreover correction value B in the modified value setting means 5 on the basis of a deviation Dr from the reference yaw rate y _b of the detected yaw rate y
K is set, and the first and second reference wheel speeds Vr ₁ and Vr ₂ are corrected by the correction value B · K, so that both the driving force and the turning motion are changed according to the operation situation intended by the driver. Is properly controlled. That yaw rate reference yaw rate y _b corrected value B · K in response to the deviation Dr is large from the y is set to be large, the correction value B · K
First and second reference wheel speeds Vr ₁ , Vr corrected by
By determining the slip state based on ₂ , the driving force and the turning force can be obtained up to the limit without exceeding the tire friction circle indicating the driving force and the turning limit of the tire.

Further, the correction value setting means 5 sets a correction value BK depending on whether the vehicle is in an over-steering state or an under-steering state, and the correction value BK is used to set the correction value BK. Since the first and second reference wheel speeds Vr ₁ , Vr ₂ are corrected, the conditions for determining the slip state of the drive wheels are changed depending on whether the vehicle is in the over-steering state or the under-steering state. Turning behavior can be obtained.

By the way, also in the rear drive vehicle, the relationship between the driving force and the limit lateral force exists in the rear wheel which is the driving wheel, and the lateral force required for the rear wheel with respect to the driving force acting on the rear wheel is the limit lateral force. If you change it, you will lose the lateral grip,
In a state where the required lateral force is estimated to exceed the limit lateral force, it is effective to increase the limit lateral force by reducing the driving force of the rear wheels. Therefore, the control of the driving force and the lateral force by the device of the present invention is also effective for a rear drive vehicle.

As a result, it is possible to realize the yaw motion desired by the driver while reducing the driving torque in accordance with the slip state of the driving wheels to suppress the reduction in the effective driving force.

Further, as another embodiment of the present invention, the slip state of the drive wheels is determined by determining whether at least one of the slip ratio and the differential value of the slip ratio exceeds a predetermined value, or whether the difference between the two drive wheel speeds exceeds a predetermined value. Alternatively, the detection may be performed. The reference yaw rate y _b may be a fixed value, in which case, the steering characteristics are set based on the yaw rate and deviation Dr. Further, the lateral acceleration of the vehicle may be used to detect the turning motion state.

C. Effects of the Invention As described above, the invention of claim (1) is based on the actual turning motion state of the vehicle based on the steering of the driver and the turning motion state reference value according to the steering of the driver. The driving slip reference value is corrected in accordance with the corrected driving slip reference value, and the slip state of the drive wheel is detected based on the corrected driving slip reference value. Therefore, information relating to the turning motion state of the vehicle (that is, based on the driver's steering). The driving wheel torque is controlled while sufficiently taking into account the actual turning motion state of the vehicle and a turning motion state reference value set according to the driver's steering, and the driver's steering amount during excessive slip The lateral force can be accurately adjusted in accordance with the driving force, so that both the driving force and the turning motion can be appropriately controlled without promoting unnecessary yaw motion. Desired turning movement It is possible to always accurately realized.

According to a second aspect of the present invention, in addition to the configuration of the first aspect, a deviation of the turning motion state detected by the turning motion detecting means from the turning motion state reference value is calculated. A deviation calculation circuit for calculating, and a correction value setting means for setting a correction value for correcting the drive slip reference value by the reference value correction means based on the deviation calculated by the deviation calculation circuit, the driver intends to do so. It is possible to appropriately control both the driving force and the turning motion in accordance with the operating situation being performed.

According to a third aspect of the present invention, in addition to the configuration of the second aspect of the present invention, it is determined whether the vehicle is in an over-steering state or an under-steering state, and the determination is made. Since a steering characteristic discriminating circuit for reflecting the result in the correction value setting of the correction value setting means is included, the condition for determining the slip state of the drive wheels is determined when the vehicle is in the oversteering state and when the vehicle is in the understeering state. And a suitable vehicle turning behavior can be obtained.

[Brief description of the drawings]

1 shows an embodiment of the present invention. FIG. 1 is a block diagram showing an overall configuration, FIG. 2 is a graph showing an example of output characteristics of a drive slip reference value setting means, and FIG. FIG. 4 is a graph showing an example of the output characteristics of the circuit, FIG. 4 is a graph showing an example of the output characteristics of the allowable deviation value setting means, and FIG. 5 is a diagram showing the relationship between the driving force and the limit lateral force. 1 ... drive slip reference value setting means, 2 ... control amount determination means, 5 ... correction value setting means, 6 ... reference value correction means, 10 ... yaw rate detection means as turning motion state detection means, 11 ... Reference yaw rate setting means as turning motion state reference value setting means, 12... Deviation calculating circuit, 13... Steering characteristic discriminating circuit, Wfl, Wfr.

Claims (3)

(57) [Claims] A drive slip reference value setting means (1) for setting a drive slip reference value for detecting a slip state of a drive wheel (Wfl, Wfr) of a vehicle, and the drive wheel (Wfl, Wfr) is driven by the drive wheel (Wfl, Wfr). A control amount determining means (2) for determining a drive torque reduction control amount for reducing the drive wheel torque when the vehicle slips over the slip reference value; Turning motion state detection means (10) for detecting an actual turning motion state of the vehicle based on the turning motion state reference value setting means (11) for setting a turning motion state reference value of the vehicle in accordance with the steering of the driver; The actual turning motion state detected by the turning motion state detecting means (10) and the turning motion state reference value setting means (1
A drive wheel torque control device for a vehicle, comprising: a reference value correcting means (6) for correcting the drive slip reference value based on the turning motion state reference value set in 1). 2. A deviation calculating circuit (12) for calculating a deviation of the actual turning motion state detected by the turning motion state detecting means (10) from the turning motion state reference value, and the reference value correcting means. And a correction value setting means (5) for setting a correction value for correcting the drive slip reference value in (6) based on the deviation calculated by the deviation calculation circuit (12). A drive wheel torque control device for a vehicle according to claim 1. 3. A correction value setting means for judging whether the vehicle is in an over-steering state or an under-steering state.
Characteristic (1)
3. The drive wheel torque control device for a vehicle according to claim 2, further comprising: