JPH0421060B2 - - Google Patents

Description

[Detailed Description of the Invention] (Technical Field) The present invention relates to a slip rate control device for a vehicle.
In particular, the present invention relates to a device for controlling the slip rate of drive wheels when starting or accelerating a vehicle.

(Technical background of the invention and its problems) In general, when a vehicle starts or accelerates, the driving force of the drive wheels is the friction force between the tires and the road surface [friction coefficient between the tires and the road surface × load on the drive wheels of the vehicle weight] (vehicle load)], the drive wheels slip, and the slip rate λ, which represents the degree of slip, can be calculated using the following equation (1), where V _W is the circumferential speed of the drive wheels and V is the speed of the vehicle. It is determined by

λ=(V _W −V)/V _W …(1) Depending on this slip ratio λ, the frictional force between the tire and the road surface (i.e., the limit value of the driving force of the driving wheels) changes as shown in Fig. 4, At a predetermined value λ ₀ , this frictional force becomes maximum. Furthermore, the frictional force between the tires and the road surface is the frictional force in the direction of vehicle travel (vertical direction), but the frictional force in the lateral direction (lateral force) increases as the slip ratio λ increases, as shown by the dotted line in the figure. descend.

Based on this point, the longitudinal friction force between the tires and the road surface is maximized to maximize the driving efficiency of the vehicle.
In addition, in order to prevent the vehicle from skidding by minimizing the decrease in the lateral frictional force between the tires and the road surface,
There is a method of detecting the slip rate λ and controlling it to a value close to a predetermined value λ ₀ . More specifically, in this method, for example, a first reference slip ratio λ 1 close to the predetermined value λ ₀ and a second reference slip ratio λ ₂ larger than the predetermined value λ ₀ are set for the slip ratio λ according to the vehicle V. The torque of the drive wheels is controlled by the drive wheel torque control device according to the value of the slip ratio λ obtained from the drive wheel speed V _W and the vehicle speed V, and the circumferential speed V _W of the drive wheels is changed. The slip rate λ of the ring is feedback-controlled to be near the predetermined value λ ₀ .

However, if the response delay of the feedback system of the driving wheel torque control device is large (for example, if the driving wheel torque control device is a fuel whose amount of fuel is controlled by a fuel injection valve installed upstream of the intake valve of the internal combustion engine) If a supply control device is used), if the control is based only on the slip rate λ, the drive wheel torque control device will only start control when it detects that the slip rate λ has become excessive. It takes a long time for the wheel torque to decrease, and during this response delay time, the slip rate λ greatly exceeds the predetermined value λ ₀ , causing a problem in that the driving force and lateral force of the vehicle decrease.

(Object of the invention) The present invention has been made in view of the above circumstances, and
The system detects excessive drive wheel slip when starting or accelerating a vehicle with high horsepower, or when starting or accelerating a vehicle on a slippery road surface, until the torque of the drive wheels is reduced. It compensates for the response delay of the control system, thereby preventing the slip rate of the drive wheels from becoming excessive, thereby maintaining the maximum frictional force between the road surface and the tires, and improving the vehicle's drive efficiency. Another object of the present invention is to provide a slip rate control device for a vehicle that minimizes a decrease in lateral force that may occur in a tire.

(Structure of the Invention) In order to achieve the above object, according to the present invention,
a drive wheel speed sensor that detects the speed of the drive wheels; a vehicle speed sensor that detects the speed of the vehicle; and a slip rate calculation means that calculates the slip rate of the drive wheels based on the detected drive wheel speed and vehicle speed; A slip rate change amount calculation means for calculating the amount of change in the slip rate of the drive wheels in a slip rate control device for a vehicle comprising a drive wheel torque control device that controls the torque of the drive wheels based on the calculated slip rate. The drive wheel torque control device is configured such that the drive wheel speed or slip rate exceeds a first drive wheel speed reference value or a first slip rate reference value, and the amount of change in the slip rate exceeds a first slip rate. If the rate change amount reference value is exceeded, or if the drive wheel speed or slip rate exceeds the second drive wheel speed reference value that is greater than the first drive wheel speed reference value or the second drive wheel speed reference value that is greater than the first drive wheel speed reference value. 2, or when the amount of change in the slip rate exceeds a second slip rate change amount reference value that is larger than the first slip rate change amount reference value. In the above case, a slip rate control device for a vehicle is provided which is characterized by reducing the torque of the driving wheels.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 shows a vehicle 1 equipped with a slip rate control device for a vehicle according to the present invention. The vehicle 1 is, for example, a front wheel drive type, and front wheels 11 and 12 are drive wheels driven by an engine 31. and rear wheel 1
3 and 14 are driven wheels. (As will be clear from the following explanation, the present invention is equally applicable to rear-wheel drive vehicles.)
The driving wheels 11, 12 and the driven wheels 13, 14 are provided with driving wheel speed sensors 21, 22 and driven wheel speed sensors 23, 24, respectively, and the driving wheel speed sensors 21, 22 determine the left and right driving wheel speeds. ω ₁ and ω ₂ are detected, and left and right driven wheel speeds ω ₃ and ω ₄ are detected by the driven wheel speed sensors 23 and 24, and these detection signals are input to the ECU 35. The ECU 35 sets the larger value of the driving wheel speeds ω ₁ and ω ₂ as the driving wheel speed V _W in the above equation (1), and the average value of the driven wheel speeds ω ₃ and ω ₄ (ω ₃ +ω ₄ )/2.
Assuming that the velocity V in the above equation (1) is, the slip rate λ is determined by the following equation (2).

λ=(ω ₁ or ω ₂ )−ω ₃ /ω ₄ /ω ₁ or ω ₂ …(2
) In this case, ω ₁ or ω ₂ means that only the one with a larger wheel speed is selected. Furthermore, the ECU 35 determines the amount of change (differential value) λ〓 of the slip rate λ. For example, in digital control, this amount of change λ is obtained from the difference between the slip rates λ obtained for each calculation processing cycle.

Further, the clutch 15 and the transmission 16, which are interposed between the engine 31 and the drive wheels 11 and 12, are each equipped with a sensor (not shown), and the clutch signal and transmission signal from these sensors are
Input to ECU35. When the ECU 35 determines that the clutch 15 is engaged based on the clutch signal, the ECU 35 controls the engine 31 by a fuel supply control device (to be described later) to control the driving wheels 11, 12.
The slip rate λ (see equation (2) above) of the drive wheels 11 and 12 is controlled by controlling the torque of the drive wheels 11 and 12. More specifically, the ECU 35 sets the first excessive slip control reference value to the slip rate λ, which is determined according to the vehicle speed V and the gear ratio detected by the transmission signal.
the reference slip rate λ ₁ and the second reference slip rate λ ₂
(λ ₂ >λ ₁ ) is set in the vicinity of the predetermined value λ ₀ , and the first and second slip rate change control reference values λ〓 are set according to the gear ratio with respect to the slip rate change _λ〓. and λ〓 ₂
(λ〓 ₂ > λ〓 ₁ ) and set these reference values λ ₁ , λ ₂
，
The fuel supply control device is controlled based on the relationship between λ〓 ₁ , λ〓 ₂ and the actual slip rate and slip rate change amount. As will be detailed later, in this embodiment, the slip rate λ and the first and second reference slip rates λ ₁ and λ ₂ are not directly used for control, but the first and second reference slip rates are used for control. The first determined based on the rate
and second reference speeds V _R1 and V _R2 and driving wheel speed ω ₁
Or the comparison result with ω ₂ and the amount of change in slip rate λ〓
The fuel supply control device is controlled based on the comparison result between the reference values λ〓 ₁ and λ〓 ₂ for controlling the amount of slip rate change. That is, the ECU 35 uses the following control law (i)
~(iii) to control the fuel supply control device.

(i) If ω ₁ or ω ₂ >V _R1 and λ〓>λ〓 ₁ , control is performed in the direction of decreasing λ, for example, fuel is cut (predictive control).

(ii) If ω ₁ or ω ₂ > V _R2, control is performed in a direction that reduces λ, for example, fuel is cut (excessive slip rate control).

(iii) If λ〓>λ〓 ₂ , control is performed in a direction to decrease λ〓, for example, fuel is cut (excessive slip rate change speed control).

As shown in control laws (i) and (iii) above, in order to control the slip of the driving wheels, in addition to the comparison control between the driving wheel speed and the reference speed, the slip rate change rate (the amount of change in the slip rate) λ is used. The slip rate λ
Even if is less than the predetermined value λ ₀ , the slip rate change rate λ〓
is large, it is predicted that the slip rate λ will greatly exceed the predetermined value λ ₀ due to the above-mentioned response delay time. Therefore, excessive slip rate speed control or predictive control is performed to improve the responsiveness of the drive wheel slip control. This is to aim for.

FIG. 2 is an overall configuration diagram of the fuel supply control device. Reference numeral 31 indicates, for example, a four-cylinder internal combustion engine, and an intake pipe 32 is connected to the engine 31. The throttle body 3 is located in the middle of the intake pipe 32.
3, and a throttle valve 33' is provided inside. A throttle valve opening (θ _TH ) sensor 34 is connected to the throttle valve 33' and converts the valve opening of the throttle valve 33' into an electrical signal to be sent to an electronic control unit (hereinafter referred to as "ECU") 3.
It is set to be sent to 5th.

A fuel injection valve 36 is provided for each cylinder between the engine 31 and the throttle body 33 in the intake pipe 32, slightly upstream of the intake valve (not shown) of each cylinder. The fuel injection valve 36 is connected to a fuel pump (not shown) and electrically connected to the ECU 35, and the opening time of the fuel injection valve 36 is controlled by a signal from the ECU 35.

On the other hand, absolute pressure (P _BA ) is supplied downstream of the throttle valve 33' of the throttle body 33 via a pipe 37.
A sensor 38 is provided, and an absolute pressure signal converted into an electrical signal by the absolute pressure sensor 38 is sent to the ECU 35.

An engine cooling water temperature sensor (hereinafter referred to as "Tw sensor") 39 is provided in the engine 31 body,
The Tw sensor 39 consists of a thermistor or the like, is inserted into the circumferential wall of the engine cylinder filled with cooling water, and supplies its detected water temperature signal to the ECU 35. Engine speed sensor (hereinafter referred to as "Ne sensor") 4
0 is installed around the camshaft or crankshaft (not shown) of the engine, and the Ne sensor 40
is a crank angle position signal (hereinafter referred to as " This TDC signal is sent to the ECU 35.

A three-way catalyst 42 is arranged in the exhaust pipe 41 of the engine 31 to purify HC, CO, and NOx components in the exhaust gas. On the upstream side of this three-way catalyst 42,
An O ₂ sensor 43 is inserted into the exhaust pipe 41 , and this sensor 43 detects the oxygen concentration in the exhaust gas and supplies an O ₂ concentration signal to the ECU 35 .

Furthermore, the ECU 35 includes the drive wheel speed sensor 2.
1, 22, the driven wheel speed sensors 23, 24, and other parameter sensors 44, such as a sensor for detecting the engagement state of the clutch 15 and a sensor for detecting the gear ratio of the transmission 16, are connected. The parameter sensor 44 sends its detected value signal to the ECU.
35.

The ECU 35 includes various sensors (the driving wheel speed sensors 21, 22, the driven wheel speed sensors 23, 2,
4. Sensor of the clutch 15 and the transmission 1
The input circuit 35a has functions such as shaping the input signal waveform from the sensor 6), correcting the voltage level to a predetermined level, and converting an analog signal value into a digital signal value, and a central processing circuit (hereinafter referred to as " The CPU 35b includes a storage means 35c for storing various calculation programs and calculation results executed by the CPU 35b, an output circuit 35d for supplying a drive signal to the fuel injection valve 36, and the like.

Each time the TDC signal is input, the CPU 35b calculates the fuel injection time of the fuel injection valve 36, which is given by the following equation, based on the engine parameter signals from the various sensors described above supplied via the input circuit 35a.
Calculate T _OUT .

T _OUT =Ti×G ₁ +G ₂ (3) Here, Ti is a reference value for the fuel time of the fuel injection valve 36, and is determined according to the engine rotation speed Ne and the intake pipe absolute pressure P _BA .

G ₁ and G ₂ are calculated based on the engine parameter signals from each of the above-mentioned sensors so that various characteristics such as starting characteristics, exhaust gas characteristics, fuel efficiency characteristics, acceleration characteristics, etc., are optimized according to the engine operating condition. These are the correction coefficient and correction variable calculated based on the formula.

The CPU 35b supplies a drive signal for opening the fuel injection valve 36 to the fuel injection valve 36 via the output circuit 35d based on the fuel injection time T _OUT determined as described above.

Therefore, fuel is independently supplied to each cylinder by the sequential fuel injection method in which fuel is supplied to each cylinder corresponding to the TDC signal, that is, the cylinder where the intake stroke starts.

FIG. 3 is a logic circuit diagram showing the configuration of the main part _of the CPU _35b in FIG. The vehicle speed calculating circuit 52 selects the one showing a faster speed among the left and right driving wheels, and calculates the average value (ω ₃ +ω ₄ )/2 (=V) of the detected driven wheel speeds ω ₃ and ω ₄ . These selection circuit 51 and vehicle speed calculation circuit 52
The slip rate calculating circuit 53 calculates the slip rate λ based on the above equation (2) based on the output signal from the . Based on the output signal from the slip rate calculating circuit 53, the differentiating circuit 54 calculates the differential value λ of the slip rate. Also,
The setting circuit 60 determines the vehicle speed V based on the output signal from the vehicle speed calculation circuit 52 and the signal representing the gear ratio output from the sensor provided in the transmission 16.
and the first and second reference speeds according to the gear ratio.
_First and second correction coefficients and correction variables K ₁ , K ₂ , C ₁ , and C ₂ for determining V R1 and V _R2 are set, and the first and second correction coefficients are set according to the vehicle speed V and gear ratio, respectively. Second slip rate change reference values λ〓 ₁ and λ〓 ₂ are set. Note that the first and second reference values λ〓 ₁ and λ〓 ₂ are set based on the response delay of the control system described above.

Excessive λ〓 determination circuit 55 compares the output signal from the differentiating circuit 54 with the output signal representing the second reference value λ〓 ₂ from the setting circuit 60 and determines the differential value λ〓 of the slip ratio.
When it is determined that is larger than the second reference value λ〓 ₂ ,
A high level signal (hereinafter referred to as "H signal") is output to the AND circuit 57 via the OR circuit 56, and in other cases, a low level signal (hereinafter referred to as "L signal") is output. On the other hand, when the clutch 15 is engaged and the engine and drive wheels are connected, the sensor provided in the clutch 15 directly outputs an H signal to the AND circuit 57. AND circuit 57 is OR circuit 56
When an H signal is input from both the clutch 15 and the clutch 15 sensor, a fuel cut signal is output, the drive signal for opening the fuel injection valve 36 is cut, and the torque of the drive wheels 11, 12 is reduced. . In this way, when the differential value λ〓 of the slip rate is larger than the second reference value λ〓 ₂ , that is, when the slip rate λ is rapidly increasing, the slip rate change rate λ〓 is controlled in the direction of decreasing it. (excessive slip rate change speed control).

The first predictive control determination circuit 58 compares the output signal from the differentiating circuit 54 and the output signal representing the _first reference value λ〓 from the setting circuit 60, and determines whether the differential value λ〓 of the slip rate is the first. When it is determined that the reference value λ〓 is larger than ₁ , an H signal is output to the AND circuit 59, and in other cases, an L signal is output. On the other hand, the first speed calculation circuit 61 uses the vehicle speed signal from the vehicle speed calculation circuit 52 and the first correction coefficient k ₁ and first correction variable C ₁ determined according to the gear ratio in the setting circuit 60 to perform the following: A first reference speed V _R1 is determined based on equation (4).

V _R1 = k ₁ V + C ₁ ... (4) The constant k ₁ is set to, for example, k ₁ = 1.016, and the constant C ₁ is a predetermined value that is not 0 (for example, 4 Km/h).
is set to A second predictive control determination circuit 63 compares the output signal from the selection circuit 51 and the output signal from the first speed calculation circuit 61 to determine the driving wheel speed.
When it is determined that V _W is higher than the first reference speed V _R1 , an H signal is output to the AND circuit 59, and in other cases, an L signal is output. AND circuit 59 is the first
When the H signal is input from both the second predictive control determination circuits 58 and 63, the H signal is output to the OR circuit 56. Then, as described above, the OR circuit 56 outputs an H signal to the AND circuit 57, and if the clutch 15 is engaged, the AND circuit 57 outputs a fuel cut signal and fuel cut is performed.
As a result, driving wheel speed V _W >first reference speed V _R1 ,
If the differential value λ〓 of the slip rate > the first reference value λ〓 ₁ , it is predicted that the slip rate λ will exhibit excessive slip due to the control delay time. The torque of the drive wheels 11 and 12 is then reduced, and the slip rate λ is controlled in a direction that is small, thereby preventing the slip rate λ from becoming excessive (predictive control).

Further, the second speed calculation circuit 62 uses the speed signal V from the vehicle speed calculation circuit 52 and the second correction coefficient k ₂ and second correction variable C ₂ determined according to the gear ratio in the setting circuit 60. The second reference speed V _R2 is determined based on the following equation (5).

V _R2 = k ₂ V + C ₂ ... (5) The constant k ₂ is set to a value that satisfies, for example, k ₂ = 1.020, and the constant C ₂ is set to a predetermined value that is not 0 (for example, 5 km/h). Set. The excessive λ determination circuit 64 receives the output signal from the selection circuit 51 and the second
When it is determined that the drive wheel speed V _W is greater than the second reference speed V _R2 by comparing the output signal from the speed calculation circuit 62 , an H signal is output to the AND circuit 57 via the OR circuit 56 . . As described above, if the clutch 15 is engaged, the AND circuit 57 outputs a fuel cut signal and fuel cut is performed. As a result, when the driving wheel speed V _W is higher than the second reference speed V _R2 , the slip rate λ is excessive, and therefore the slip rate λ is controlled in a direction to become smaller (excessive slip rate control).

Furthermore, since the AND circuit 57 is provided as described above and the slip rate is not controlled when the clutch 15 is completely disengaged, the drive wheels 11,
There is no problem in which unnecessary slip rate control is performed even though no driving force is generated in clutch 12, and runaway control is avoided even though clutch 15 is completely disengaged and the engine speed is low. There is no problem of outputting a fuel cut signal and stalling the engine 31.

FIG. 5a is a graph showing an example of setting the first and second reference speeds V _R1 and V _R2 when the gear position is set to 1st or 2nd speed, according to the present invention. The solid line in the figure represents the relationship between the vehicle speed V and the driving wheel speed V _W when the slip rate λ = 0, that is, the driven wheels and the driving wheels are rotating at the same speed.The broken line represents the slip rate λ = λ ₀ (approximately 0.15) represents the above relationship when the drive wheels are rotating. On the other hand, V _R1
is set as shown in the dashed line, and V _R2 is set as shown in the chain double dotted line. Note that the reference slip rates λ ₁ and λ ₂ corresponding to the two reference speeds set in this way are obtained by the following equations (6) and (7), respectively.

λ ₁ =1-1/k ₁ +C ₁ /V (6) λ ₂ =1-1/k ₂ +C ₂ /V (7) These equations (6) and (7) are It is obtained by substituting V _R1 and V _R2 of the above equations (4) and (5) into V _W , respectively.

FIG. 5b shows the first and second reference slip rates λ ₁ and λ ₂ obtained from the above-mentioned equations (6) and (7).
As can be seen from this figure, at low vehicle speeds, the reference slip rates λ ₁ and λ ₂ are set to high values to allow large slips and to prevent engine stall due to the fuel cutoff control of the present invention. Furthermore, as the vehicle speed increases, the reference slip rates λ ₁ and λ ₂ gradually change.
This allows for proper control when transitioning from low to high speeds.
In other words, if the reference slip rates λ ₁ and λ ₂ are switched to values close to the predetermined value λ ₀ at the same time as the vehicle speed reaches a speed that does not cause engine stall, the driving wheels will suddenly obtain the maximum frictional force at the time of switching (the fourth (See figure) The vehicle grips the road surface, causing a shock to the vehicle body, but this can be avoided if the reference slip rates λ ₁ and λ ₂ are determined as in this embodiment (Figure 5b). There are no problems, and it is possible to prevent sudden changes in driving force while allowing a certain amount of slip.

The first and second speed calculation circuits 61 and 62 calculate the first and second reference speeds V _R1 and V _R2 by performing integration and addition according to equations (4) and (5) each time the control is performed. However, it is preferable to read the calculated values from the V-V _R1 table and the V-V _R2 table stored in advance in the storage means stage 5c. This reduces the processing time and reduces the slip rate. Control responsiveness is improved.

FIG. 6 shows another embodiment of the invention. In the embodiment shown in FIG. 3, the drive wheel speeds ω ₁ , ω ₂ are compared with the reference speeds V _R1 , V _R2 as a condition for performing excessive slip rate control and predictive control. Vehicle speed V according to the characteristics in Figure 5 b
A table of values of reference slip ratios λ ₁ and λ ₂ corresponding to the values of the slip ratios λ ₁ and λ 2 is stored, and the first and second reference slip ratios λ 1 and λ ₂ read from these tables and the output of the slip ratio calculation circuit 53, That is, the actual slip rate λ
I'm trying to compare.

That is, in this embodiment, the ECU 35 controls the fuel supply control device according to the following control laws ('), ('), and (iii).

(') If λ>λ ₁ and λ〓>λ〓 ₁ , control is performed in the direction of decreasing λ, for example, fuel is cut (predictive control).

(') If λ>λ ₂ , control is performed in the direction of decreasing λ, for example, fuel is cut (to prevent excessive slip rate).

(iii) If λ〓>λ〓 ₂ , control is performed in the direction of decreasing λ〓, for example, fuel is cut (to prevent excessive slip rate change speed).

The configuration of this embodiment can also provide the same effects as the configuration shown in FIG. 3 described above.

FIGS. 7a and 7b are graphs (FIG. 7a) showing temporal changes in the driving wheel speed _VW and vehicle speed V of the vehicle obtained by the driving wheel slip control device of the embodiment shown in FIG. FIG. 7B is a graph (FIG. 7b) showing a change over time in the amount of change λ in the slip rate determined from the relationship between the wheel speed _VW and the vehicle speed V. The drive wheels start accelerating and the first reference speed V _R1 for predictive control determined based on the vehicle speed V (dotted chain line)
, that is, in periods 78, 80, and 82, the comparator 63 in FIG.
Output to 9. Furthermore, the acceleration of the drive wheels progresses, and the second
When the reference speed V _R2 (double-dashed line) is exceeded, that is, 7
During periods 2, 74 and 76, comparator 64 of FIG.
outputs an H signal to the OR circuit 56, so if the clutch is engaged, the H signal of the OR circuit 56 is ANDed.
A fuel cut signal is output via circuit 57. The manner in which the slip rate variation λ〓 changes when the driving wheels are slipping as shown in FIG. 7a will be explained with reference to FIG. 7b. When the output of the differentiating circuit 54 in FIG. 3, that is, the amount of change in the slip rate (solid line) exceeds the first reference value λ ₁ (dotted chain line), that is, in periods 84, 86, and 88, Comparator 58 outputs an H signal to AND circuit 59. The AND circuit 59 outputs an H signal during the period when the outputs of the comparator 58 and the comparator 63 are both H signals, that is, the periods 90, 92, and 94, and the clutch is engaged via the OR circuit 56. If so, the AND circuit 57 outputs a fuel cut signal. When the slip rate variation λ〓 further increases and exceeds the second reference value λ〓 ₂ (two-dot chain line),
That is, in periods 96 and 98, the comparator 55 in FIG.
outputs an H signal, so OR circuit 56 and AND
If the clutch is engaged, a fuel cut signal is output via circuit 57. Therefore, the rising edges 100, 104 and 108 of the fuel cut signal are 84 and 108, respectively.
Starting from the starting point of 98,94, falling 102,1
06 occurs at the end of 72,74.

FIG. 7c shows how the change in driving wheel speed shown in FIG. 7a is converted into a slip ratio λ. Therefore, FIGS. 7b and 7c show the slip rate λ (FIG. 7c) and the time of the slip rate λ〓 (FIG. 7b) of the driving wheel obtained by the driving wheel slip control device of the embodiment shown in FIG. It is a graph showing changes. FIG. 7c is a graph showing how the slip rate λ changes when the speeds of the driven wheels and the driving wheels change as shown in FIG. 7a, and the output of the slip rate calculation circuit 53 in FIG. It changes as shown by the solid line. Furthermore, as mentioned above, the first and second reference slip rates λ ₁ and λ ₂ are obtained by simply converting the first and second reference speeds into reference slip rates using equations (6) and (7). Therefore, periods 110 and 72,
112 and 74, 114 and 76, 116 and 78, 1
Since 18 and 80 and 120 and 82 are completely synchronized, the fuel cut signals finally obtained are also exactly the same.

When excessive slip occurs in this way, excessive slip rate change speed control or predictive control can detect the excessive slip condition at an early stage, and furthermore, over-read large slip rate prevention control can ensure that excessive slip is occurring. Since fuel continues to be cut, responsive control can be performed.

Moreover, FIG. 8 shows yet another embodiment of the present invention. In the embodiment shown in FIG. 8, as the conditions for performing the slip rate control, the driving wheel speeds ω ₁ and ω ₂ are compared with the reference speed V _R1 for predictive control, and the direct slip rate λ is used for excessive slip rate prevention control. and a second reference value slip rate λ ₂ . That is, in this embodiment, the ECU 35 uses the control law
Controlling the fuel supply control device according to (i), (′), and (iii).

Furthermore, FIG. 9 shows yet another embodiment of the present invention. In the embodiment shown in FIG. 9, as the conditions for controlling the driving wheels, the direct slip rate λ is compared with the first reference slip rate λ ₁ for predictive control, and the driving wheel speed ω ₁ is used for excessive slip rate prevention control. , ω ₂ and the reference speed V _R2 are compared. That is,
In this embodiment, the ECU 35 uses the control laws ('), (ii),
and (iii) controlling the fuel supply control device.

The configurations shown in FIGS. 8 and 9 can also provide the same effects as the configurations shown in FIGS. 3 and 6 described above.

Furthermore, in the above method, the speed V is set to the driven wheels 13,
14, there is no effect of the difference between the left and right inner wheels when the vehicle turns, that is, there is no error in detecting the speed value V depending on whether the vehicle is turning to the right or to the left. , high-precision slip rate control can be performed. Note that for detecting the speed V, instead of using the driven wheel speed sensors 23 and 24, a speed sensor that detects the relative speed between the vehicle and the road surface using electromagnetic waves or ultrasonic waves generated from the vehicle may be used. Furthermore, the drive wheel speed V _W is set to the left and right drive wheels 11,1.
Since we adopted the HI-Select method, which selects the larger of the two speeds, the driving force is controlled by the wheel with the smaller slip ratio between the road surface and the tire, that is, the friction coefficient. Become. In this case, in normal wheels, a differential device is interposed between the left and right drive wheels 11 and 12, so that neither of the two drive wheels 11 and 12 is activated in any case when traveling in a straight line or when turning. Compared to the LOW-Select method, in which the driving force is not controlled to exceed the frictional force of the selected drive wheel, and as a result, the speed of the left and right drive wheels is selected to be the smaller one, the drive force on both sides is The wheels do not slip together and sufficient slip rate control can be performed. In addition, by adopting the HI-Select system, it is possible to reduce the drop in lateral force that can be generated by the tires on both drive wheels.

In the above embodiment, a fuel supply control device is used as the drive wheel torque control device, and the drive torque of the drive wheels 11 and 12 is reduced by cutting fuel at a predetermined time. However, the present invention is not limited to this, and the driving torque of the driving wheels 11 and 12 may be reduced by delaying the ignition timing using an ignition timing control device.

(Effects of the Invention) As explained above, according to the present invention, the slip rate of the drive wheels that occurs when a vehicle with large horsepower starts or accelerates, or when a vehicle starts or accelerates on a slippery road surface is reduced. It is possible to compensate for the response delay of the control system from when it is detected that the torque has become excessive until the torque of the driving wheels is reduced, thereby preventing the slip ratio of the driving wheels from becoming excessive.
That is, when a sudden slip occurs at the time of starting, excessive slip rate change control based on the slip rate change amount is effective, and predictive control based on both the slip rate (or driving wheel speed) and the slip rate change amount, When the slip rate of the drive wheel is about to deviate from a predetermined range, it can be predicted and controlled in advance so that it stays within the predetermined range, and the excessive slip rate change amount control can be terminated. Therefore, it is avoided that the torque reduction is stopped immediately, and furthermore, the excessive slip rate control based on the slip rate (or drive wheel speed) is effective for feedback controlling the slip rate within the predetermined range during the execution of the torque reduction control. It is valid. Therefore, by using the above-mentioned excessive slip rate change amount control, predictive control, and excessive slip rate control in combination, it is possible to perform slip rate control suitable for various slip rate occurrence states, and as a result, the relationship between the road surface and the tires can be controlled. The maximum frictional force between the two can be maintained. Therefore,
Vehicle driving efficiency can be improved, and
A decrease in lateral force that may be generated by the tire can be suppressed to a minimum.

[Brief explanation of drawings]

Fig. 1 is a block diagram of a vehicle equipped with the vehicle slip rate control device of the present invention, Fig. 2 is a block diagram of a fuel supply control device which is a driving wheel torque control device, and Fig. 3 is a logic diagram of the main parts of the ECU 35. Circuit diagram, Figure 4 is a characteristic diagram of the friction force between the tire and the road surface versus slip rate, Figure 5a is a graph showing the relationship between the reference speed of the driving wheels and the vehicle speed, and Figure 5b is the reference of the driving wheels. A graph showing the relationship between slip rate and vehicle speed, Figure 6 is a logic circuit diagram showing another example of the main part of the ECU, and Figure 7 is a graph showing the relationship between slip rate and vehicle speed.
The figure is a graph showing the driving wheel speed, vehicle speed, slip rate, and the amount of change thereof over time, and FIGS. 8 and 9 are logic circuit diagrams showing still other examples of the essential parts of the ECU 35. be. 11, 12... Drive wheel, 13, 14... Driven wheel, 1
5... Clutch, 16... Transmission, 21, 22... Driving wheel speed sensor, 23, 24... Driven wheel speed sensor,
31...Engine, 35...ECU (driving wheel torque control device).

Claims (1)

[Claims] 1. A drive wheel speed sensor that detects the speed of the drive wheels, a vehicle speed sensor that detects the speed of the vehicle, and a slip rate calculation means that calculates the slip rate of the drive wheels based on the detected drive wheel speed and vehicle speed. and a drive wheel torque control device that controls the torque of the drive wheels based on the calculated slip rate, a slip rate change amount calculation that calculates the amount of change in the slip rate of the drive wheels. The drive wheel torque control device is configured such that the drive wheel speed or slip rate exceeds a first drive wheel speed reference value or a first slip rate reference value and the amount of change in the slip rate exceeds a first drive wheel speed reference value or a first slip rate reference value. If the slip ratio change amount exceeds the reference value, or the driving wheel speed or slip ratio is larger than the first driving wheel speed reference value or the second driving wheel speed reference value or the first slip ratio reference value. Either one of the cases where the slip rate exceeds the second slip rate reference value, or the amount of change in the slip rate exceeds the second slip rate change standard value which is larger than the first slip rate change standard value. A slip rate control device for a vehicle, characterized in that the torque of a drive wheel is reduced in two or more cases.