JP3079857B2 - Wheel slip control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wheel slip control device and, more particularly, to a wheel slip control device configured to detect a slight occurrence of a slip on a drive wheel and to control a drive force transmitted to the drive wheel.

[0002]

2. Description of the Related Art Conventionally, a wheel slip control device has been developed which suppresses the rotation of a drive wheel when a slip occurs, in order to prevent the slip of the drive wheel caused when the vehicle is accelerated. As this kind of wheel slip control device, there is a device having a configuration as disclosed in, for example, Japanese Patent Application Laid-Open No. 63-20253. In the device of this publication, the drive wheel speed is equal to or higher than a preset control start reference vehicle speed (not lower than a set slip ratio).
In this case, the engine output is reduced to suppress the driving force transmitted to the driving wheels, thereby preventing the driving wheels from slipping.

[0003]

[SUMMARY OF THE INVENTION] However, in the above arrangement, immediately to the drive wheels even if the driving wheel speed V _R as shown in FIG. 9 consist follower wheel speeds V _F and large (V _R> V _F) Does not start the drive force transmitted to the vehicle (traction control control). Note that FIG. 9 and FIGS.
In the above, “TRC control” is an abbreviation for traction control control.

[0004] That is, conventionally, when the speed difference between the drive wheel against the driven wheel exceeds a predetermined slip rate, the drive wheel speed for the driven wheel speed V _F V _R control start reference vehicle speed V _S (control start slip ratio) because of the additional level atmospheric (V _R> V _S), starts the traction control. Thus, for example when the drive wheel has a slight slip, since the driving wheel speed V _R is not a control start reference vehicle speed V _S or higher against the follower wheel speed _{V F (V R <V S} ), the slip control is not performed, the drive Wheel slip cannot be prevented.

[0005] The control start reference vehicle speed V _S is determined by the wheel speed disturbance (temporary apparent slip) due to unevenness of the road surface.
In addition, it is necessary to set in consideration of the vibration of the driving system and the correction error of the tire diameter. Therefore, when the control start reference vehicle speed V _S becomes set too low, for example because the driving force control will be performed each time the drive wheel passes an unevenness of the road surface, lower the control start reference vehicle speed V _S There is a limit to setting the value.

However, when the vehicle travels on a wet road surface or a sloping road, etc., a slight slip tends to occur continuously. The lateral force of the tire becomes maximum when the slip ratio = 0%. Since this lateral force decreases with an increase in the slip ratio, the balance of the lateral forces of the front and rear wheels is lost near the maximum lateral force even when a slight slip occurs, and the vehicle becomes unstable.

Therefore, in the above-mentioned conventional apparatus, when the drive wheels travel on a road surface where a slight slip is likely to occur, such as a slightly wet road surface or a sloping road, poor acceleration due to a large slip or rear wheel misalignment in the lateral direction. Although not such vehicle attitude varies greatly Te, the vehicle by slight slippage of the drive wheels are continuously generated is to travel remains unstable, the driving wheel speed subsequently against the driven wheel speed V _F order to perform the first traction control when V _R becomes the control start reference vehicle speed or higher, there is a problem easily causing discomfort to the driver.

In view of the above problems, the present invention calculates the slip occurrence time or slip amount of a drive wheel to determine the occurrence of minute slip on the drive wheel, and drives the drive wheel to prevent the occurrence of minute slip. It is an object of the present invention to provide a wheel slip control device configured to reduce a driving force transmitted to a wheel.

[0009]

FIG. 1 is a principle diagram of a wheel slip control device according to the present invention.

In the drawing, the invention of claim 1 is based on a wheel speed detecting means A1 for detecting the rotational speed of each wheel, and a control start reference based on the speed of the driven wheel A2 detected by the wheel speed detecting means A1. A wheel speed comparing means A4 for comparing the speed with the speed of the driving wheel A3; and when the speed difference between the driven wheel A2 and the driving wheel A3 is detected by the wheel speed comparing means A4, the speed is determined. Clocking means A5 for measuring the time of occurrence of the difference, the driven wheel A2 and the driving vehicle
Excessive slip or minute slip based on the speed difference from wheel A3
A first slip determining means for determining whether the lips, the
The occurrence of a minute slip is determined by the first slip determination means.
When another, the determined presence or absence of slip occurrence based on timed speed difference generation time by the timing means A5, the second slip is determined that slip occurs when the speed difference generating time is longer or equal to a predetermined time and determining means A6, the first
Is judged to be excessive slip by the slip discriminating means.
And when the second slip discriminating means A6 determines that a slip has occurred, a driving force control means A7 for controlling so as to reduce the driving force transmitted to the driving wheel A3. And

FIG. 2 is a principle diagram of a wheel slip control device according to the present invention.

In the figure, a second aspect of the present invention is a wheel speed detecting means A1 for detecting the rotational speed of each wheel, and a control start reference speed based on the speed of the driven wheel A2 detected by the wheel speed detecting means A1. the drive wheel and the wheel speed comparison means A4 for comparing the speed of the drive wheels A3, and the driven wheel A2
Excessive slip or minute slip based on speed difference from A3
A first slip determining means for determining whether-up, said
The occurrence of minute slip is determined by the slip determination means 1
When it is performed, the following wheels A2 and the driving wheels A3
The slip amount of the drive wheel A3 is calculated from the speed difference,
A slip generation amount calculating means A8 for calculating the sum of the slip generation amounts by integrating the slip amounts , and determining whether or not a slip has occurred based on the total of the slip generation amounts calculated by the slip generation amount calculation means A8. It is determined that a slip has occurred when the total amount of slip occurrences exceeds a predetermined value.
The second slip determination means A9 and the first slip determination
When it is determined that excessive slip has occurred by another means,
A driving force control means A10 for controlling the driving force transmitted to the driving wheel A3 to be reduced when the second slip discriminating means A9 determines that a slip has occurred;
It is characterized by comprising.

[0013]

According to the first aspect , the first slip discriminating means is provided.
Based on the speed difference between the driven wheel A2 and the drive wheel A3,
No excessive slip has occurred and a slight slip has occurred.
The life is determined and the second slip determination means A6
If the speed difference occurrence time is longer than the specified time, drive wheels
A3 determines that a minute slip has occurred, and the driving force control means A7 controls the driving force transmitted to the driving wheel A3 to decrease so that the driving wheel A
3. Prevent the occurrence of slight slip. In addition, driven wheel A
Excessive slip is generated based on the speed difference between the wheel 2 and the driving wheel A3.
If it has occurred, the second slip determination means A6
The driving force control means A7 does not perform the
Control is performed to reduce the driving force transmitted to A3.

Further, according to the second aspect , the first slip size
The speed difference between the driven wheel A2 and the drive wheel A3 is determined by another means.
No excessive slip has occurred based on the
When the occurrence of slip is determined, the slip occurrence amount calculating means A8
Drive from the speed difference between driven wheel A2 and drive wheel A3
The slip amount of the wheel A3 is calculated, and the slip amount is integrated.
To determine the total amount of slip generated by the drive wheel A3.
When the sum of the amount of generated trips is equal to or greater than a predetermined value, the second switch
The lip discriminating means determines that a slight slip has occurred on the driving wheel A3, and the driving force controlling means A10
Controls the driving force transmitted to the driving wheel A3 so as to reduce the driving force transmitted to the driving wheel A3. Also, the speed between the driven wheel A2 and the driving wheel A3.
If excessive slip has occurred based on the difference,
Without performing the determination process by the second slip determination unit A6
Driving force transmitted to driving wheel A3 by driving force control means A7
Is controlled to decrease.

[0015]

3 and 4 show an embodiment of a braking control device according to the present invention.

In both figures, an example in which the present invention is applied to a vehicle provided with an acceleration slip control device and an anti-skid control device is shown below. FIG. 3 is a schematic diagram of an engine brake system and a control system of the front engine / rear drive (FR) type vehicle of this embodiment.

In both figures, a vehicle having an acceleration slip control device 1 includes a brake master cylinder 2, wheel cylinders 5 and 6 for left and right front wheels 3 and 4 as idle wheels, and left and right rear wheels 7 and 8 as drive wheels. A hydraulic source 11, an anti-skid control hydraulic circuit 12, and an acceleration slip control hydraulic circuit 13 are provided between the wheel cylinders 9 and 10.
The vehicle of the present embodiment is a vehicle equipped with an automatic transmission.

In the brake hydraulic circuit extending from the first hydraulic chamber 2a of the brake master cylinder 2 to the wheel cylinders 5, 6 of the left and right front wheels 3, 4, left and right front wheel anti-skid control capacity control valves 14, 15 are provided. Has been established. The brake hydraulic circuit extending from the second hydraulic chamber 2b of the brake master cylinder 2 to the wheel cylinders 9, 10 of the left and right rear wheels 7, 8 includes a proportioning valve 16, a rear wheel anti-skid control capacity control valve 17, A first solenoid valve 18, a check valve 19, and a displacement control valve 20 for accelerating slip control are provided in parallel.

At the time of anti-skid control, the first solenoid valve 18 is not energized and is at the position shown in the drawing.
The rear wheel anti-skid control displacement control valve 17 and the acceleration slip control displacement control valve 20 are kept in communication. or,
Control input port 2 of acceleration slip control displacement control valve 20
Since the second solenoid valve 21 and the third solenoid valve 22 arranged in series with 0a are not energized and are at the positions shown in the figure, the acceleration slip control displacement control valve 20
Is kept in communication with the reservoir 23 of the hydraulic power source 11.

Accordingly, the acceleration slip control displacement control valve 2
The zero piston 20c is maintained at the position shown in the figure by the bias of the spring 20d. At this time, the rear-wheel anti-skid control displacement control valve 17 is connected to the rear-wheel second switching valve 25 connected in series to the rear-wheel first switching valve 24 communicating with the first control input port 17a. The following three states change according to the combination of excitations.

(1) Pump drive motor 26 of hydraulic power source 11
Output port 29a of a regulator 29 that converts a hydraulic pressure from a pump 27 driven by a motor and an accumulator 28 that accumulates the hydraulic pressure into a hydraulic pressure corresponding to a brake operation amount
And a communication state with the first control input port 17a,
(2) First control input port 17a, regulator 29,
(3) a state of communication between the first control input port 17a and the reservoir 23;

The second control input port 17a is always in communication with the output port 29a of the regulator 29. Accordingly, the rear wheel anti-skid control displacement control valve 17 operates as follows in accordance with the above three states.

That is, the pressure in the first hydraulic chamber 17c having the first control input port 17a is increased (1), maintained (2) or reduced (3), and is reduced to the pressure in the first hydraulic chamber 17c. The volume of the brake hydraulic chamber 17d changes accordingly.
As a result, the rear wheel anti-skid control displacement control valve 17
Increases (1), maintains pressure (2), or reduces (3) the pressure in the left and right rear wheel cylinders 9, 10 via the first solenoid valve 18 or the check valve 19.

Incidentally, the left front wheel first and second switching valves 30, 31,
The left and right front wheel anti-skid control displacement control valves 14 and 14 are energized and de-energized by the right and left front wheel first and second switching valves 32 and 33, respectively.
15 also acts on the left and right front wheel cylinders 5 and 6 in the same manner. Each of the switching valves 24, 25, 30, 3 as described above
Excitation and non-excitation of 1, 32, and 33 are performed by an anti-skid control device (not shown).

At the time of the acceleration slip control, the first solenoid valve 18 is excited to switch to the shut-off state. Therefore, the first solenoid valve 18 and the check valve 19
Thus, the communication between the rear wheel anti-skid control displacement control valve 17 and the acceleration slip control displacement control valve 20 is cut off. At this time, the acceleration slip control displacement control valve 20
Changes to the following four states by a combination of excitation and non-excitation of the second and third solenoid valves 21 and 22 communicating with the control input port 20a.

(11) The state of communication between the accumulator 28 and the control input port 20a, (12) the accumulator 28
Communicating with the control input port 20a via a throttle valve,
(13) A state of communication between the reservoir 23 and the control input port 20a via the throttle valve, and (14) a state of communication between the reservoir 23 and the control input port 20a. Therefore, capacity control for acceleration slip control corresponding to the above four states. Valve 20 operates as follows.

That is, the pressure in the control hydraulic chamber 20b having the control input port 20a increases (11) and gradually increases (1).
2), the pressure in the control hydraulic chamber 20b is changed by gradually reducing the pressure (13) or gradually reducing the pressure (14), and the piston 20c is opposed to the biasing force of the spring 20d as shown in FIG.
Move in the middle left and right directions.

Thus, the hydraulic pressure is supplied to the left and right rear wheel cylinders 9 and 10 from the output port 20f of the brake hydraulic chamber 20e. Therefore, the pressure in the left and right rear wheel cylinders 9 and 10 is increased (11), gradually increased (12), gradually reduced (13), or gradually reduced (1).
4) Yes.

The acceleration slip control device 1 includes a pedal switch 34 for outputting an on / off signal in response to the operation of the brake pedal 34a, and a left front wheel rotational speed sensor (wheel speed detecting means) 35 for detecting the rotational speed of the left front wheel 3. A right front wheel rotation speed sensor (wheel speed detection means) 36 for detecting the rotation speed of the right front wheel 4; a rear wheel rotation speed sensor (wheel speed detection means) 37 for detecting the rotation speeds of the left and right rear wheels; An engine speed sensor 38 for detecting speed and an acceleration sensor 39 for detecting acceleration of the vehicle are provided. still,
The detection signal output from the acceleration sensor 39 is used, for example, to correct the estimated vehicle speed at the time of deceleration when performing acceleration slip control, and to obtain the inclination angle of the vehicle in the front-rear direction as described later. used.

The detection signals output from the sensors 35 to 39 are input to the acceleration slip control circuit 40. or,
The acceleration slip control circuit 40 includes the first to third solenoid valves 18, 21, 22 and the pump drive motor 26.
Drive control.

The acceleration slip control device 1 detects the occurrence of a slip based on the difference between the vehicle speed and the wheel rotation speed based on the detection signals output from the sensors 35 to 39, and performs an engine slip control prior to the acceleration slip control by the brake. The acceleration slip control is performed by adjusting the intake air amount of the vehicle.

That is, the acceleration slip control device 1 outputs a control signal to a driving motor 46 of a sub-throttle valve 44 provided in an intake pipe 42 of an engine that applies driving force to the driving wheels 7 and 8. The closing prevents an excessive slip due to the rapid opening of the main throttle valve 49 linked to the accelerator pedal 48.

The throttle position sensor 49a includes an idle switch that issues an ON signal when the main throttle valve 49 is fully closed. The throttle position sensor 49a outputs a signal corresponding to the opening to execute the map processing and the like described later in the acceleration slip control circuit 40. Output to

Here, the configuration of the acceleration slip control circuit 40 will be described with reference to FIG.

The acceleration slip control circuit 40 includes a CPU 40
a, ROM 40b, RAM 40c, backup RAM
The input port 40f and the output port 4 are configured as a logical operation circuit around the
0g for input and output with the outside.

The detection signals from the pedal switch 34, the engine speed sensor 38, the acceleration sensor 39, and the throttle position sensor 49a are directly or to the left and right.
The detection signals of the rotation speed sensors 35 to 37 of the right rear wheel are transmitted from the input port 40f to the CP through the waveform shaping circuit 40h.
It is input to U40a.

Further, the driving circuits 40i to 40i to 4 of the first to third solenoid valves 18, 21 and 22, the pump driving motor 26 and the sub throttle valve driving motor 46 described above.
0n is also provided, and the CPU 40a outputs a control signal to the drive circuits 40i to 40n via the output port 40g. Further, a control program for executing a process for preventing the vehicle from moving backward when the vehicle stops on an uphill road, as described later, is input to the CPU 40a. That is, when the driving force transmitted from the engine to the left and right rear wheels 7, 8 as the driving wheels is stopped on an uphill road, the braking force is applied when the driving force is smaller than the reversing force acting on the vehicle.

Here, the processing executed by the CPU 40a will be described with reference to FIG.

The CPU 40a repeatedly executes the processing of S1 to S18 shown in FIG. 5 every predetermined time. In FIG. 5, in step S1 (hereinafter "step" is omitted), a signal from a rear wheel rotational speed sensor 37 for detecting the rotational speed of the left and right rear wheels 7, 8 serving as drive wheels is read and the drive wheel speed V is read. _R
Is calculated. Subsequently, left and right front wheel rotation speed sensors 35 and 36 for detecting rotation speeds of left and right front wheels 3 and 4 serving as driven wheels.
The signals from the calculating the read follower wheel speeds V _F (S
2).

[0040] In the next S3, and calculates the following equation a control start reference speed V _S.

V _S = V _T3 + K (1) V _T3 = V _F + C (2) where V _T3 is the control target speed, K is the allowable slip amount, and C is the target slip amount.

Then, at S4 (wheel speed comparison means, first
The slip determination means), comparing the driving wheel speed V _R and the control start reference velocity V _S. In this S4, V _R > V
_{If S} , proceed to S5; if V _R ≤ V _S , S10 (wheel
Speed comparing means, first slip determining means) . If V _R > V _S in S4, the driving wheel speed V _R
There therefore sufficiently greater than the follower wheel speeds V _F, excessive slip proceeds to step S5 it is judged that the generated left and right rear wheel 7, 8 as a drive wheel.

In S5, since an excessive slip has occurred at the driving wheel, a timer T for counting the time of occurrence of the minute slip is set.
Reset to zero. Then, the process proceeds to S6, where the integrated value A of the micro slip counter for integrating the micro slip generation amount is reset to zero.

In the next S7, the control target speed _VT3 is set. However, it is set so that C> D in the above equation (2). Then, the process proceeds to S8, the driving wheel speed V _R to execute the traction control to control target velocity V _T3 (driving force control means). That is, the driving motor 46
And a sub-throttle valve 44 provided in the intake pipe 42 of the engine is closed. As a result, the main throttle valve 49 linked to the accelerator pedal 48 is rapidly opened, so that the left and right rear wheels 7,
8 prevents the occurrence of excessive slip.

Further, the vehicle of this embodiment has the acceleration slip control device 1 including the anti-skid control hydraulic circuit 12 and the acceleration slip control hydraulic circuit 13 described above. The first solenoid valve 18 is excited and switches to the shut-off state. Therefore, the communication between the rear wheel anti-skid control displacement control valve 17 and the acceleration slip control displacement control valve 20 is cut off by the first solenoid valve 18 and the check valve 19. At this time, the acceleration slip control displacement control valve 20 changes to the four states (11) to (14) described above, and the pressure in the control hydraulic chamber 20b having the control input port 20a is increased (11), Gradually increase pressure (12), gradually reduce pressure (13),
Alternatively, the pressure in the control hydraulic chamber 2 is gradually reduced (14).
The volume in 0b changes, and the piston 20c moves left and right in FIG.

Thus, the hydraulic pressure is supplied to the left and right rear wheel cylinders 9 and 10 from the output port 20f of the brake hydraulic chamber 20e. Therefore, the pressure in the left and right rear wheel cylinders 9 and 10 is increased (11), gradually increased (12), gradually reduced (13), or gradually reduced (1).
4) to prevent the left and right rear wheels 7, 8 from slipping.

In the next S9, it is checked whether or not the traction control control has been completed. If the left and right rear wheels 7, 8 are no longer slipping, it is determined that the traction control control has been completed and the process returns to S1. . However, when the left and right rear wheels 7, 8 are slipping, the process of S8 is repeated.

In S4 described above, if V _R ≤ V _S , the process proceeds to S10, where the rotational speeds of the left and right front wheels 3, 4 and the left and right speeds are determined.
The presence / absence of a minute slip is determined by comparing the rotational speeds of the right rear wheels 7 and 8 (wheel speed comparing means). If V _R > V _F + α in S10, the difference between the rotation speeds of the left and right front wheels 3, 4 and the rotation speeds of the left and right rear wheels 7, 8 is equal to or greater than a predetermined value, and the process proceeds to S11, where V _R ≦ V _F. If it is + α, the process proceeds to S17 because the difference between the rotational speeds of the left and right front wheels 3, 4 and the rotational speeds of the left and right rear wheels 7, 8 is equal to or less than a predetermined value.

[0049] As shown in FIG. 6, will be to determine the presence or absence of micro-slip caused by a change in the driving wheel speed V _R for only large V _F + alpha alpha than the follower wheel speed V _F, the driving wheel speed V _R is when V _R> V _F + α time T ₀ from when has elapsed, traction control is started as described below.

The above α is a coefficient for preventing the drive wheel from calculating as a very small slip even if the drive wheel slips on the uneven road surface, and is set so that D <α <C. I do.

In S11, since the difference between the rotational speeds of the left and right front wheels 3 and 4 and the rotational speeds of the left and right rear wheels 7 and 8 is greater than a predetermined value and a minute slip has occurred, a timer for measuring the minute slip occurrence time is performed. T is incremented by 1 so that T = T + 1 (timing means). That is, the timer T counts up every calculation cycle.

[0052] In the next S12, since slight slip occurs, it calculates the current amount of slip _{S (= V R -V F)} . Then, the process proceeds to S13, where an integrated value A (= A + S) of the minute slip counter is calculated. That is, the integral value (A = ∫Sdt) of the slip generation amount at the drive wheel is calculated.

[0053] When the minor skid occurrence amount in S13 as described above is calculated, the process proceeds to S14, slight slip occurrence time T to check whether reaches the set time T ₀ which is set in advance (second slip Determination means). If S14
When the micro slip occurrence time T has not reached the set time T ₀ (T ≦ T ₀ ), the process proceeds to S15, where the integrated value A of the micro slip counter has reached the preset reference integrated value A ₀ . It is checked whether it is (slip generation amount calculation means, second slip determination means). Further, in S14, slight slip occurrence time T has reached the set time T ₀ (T> T ₀₎ time, the process proceeds to S16.

[0054] In the above S15, the integrated value A of the counter for small slip reaches the reference accumulated value A ₀ (A> A
_{If 0} ), it is determined that the slip integrated value A is excessive, and the process proceeds to S16. As shown in FIG. 7, even if the minute slip occurrence time T has not reached the set time T _0, when the accumulated value A of the minute slip counter reaches the reference accumulated value A ₀ , the traction control is performed at this time. Control is started.

However, in S15, for a slight slip
The integrated value A of the counter is the reference integrated value A ₀Not reached
(A <A₀), The processing of S16 and S8, S9 is executed.
A series of processing is temporarily ended without performing.

As described above, in this embodiment, since the occurrence of the minute slip is constantly monitored from both the condition of the minute slip occurrence time T and the integrated value A of the minute slip occurrence amount, the left and right wheels that are the driving wheels are surely monitored. It can be determined that a slight slip has occurred in the right rear wheels 7, 8, and the reliability of the traction control control is improved.

Therefore, in S14, when the minute slip occurrence time T reaches the set time T ₀ (T> T ₀ ), or in S15, the integrated value A of the minute slip counter reaches the reference integrated value A ₀ ( When A> A ₀ ), S1
Then, the program proceeds to 6, and a new control target speed V _T3 ′ is calculated and set by the following equation.

V _T3 '= V _F + D ...
(3) Here, D is a target slip amount, which is smaller than the target slip amount C in S7 (D <C).

As shown in FIG. 8, the control target speed V _T3 ′ (see the diagram in FIG. 8) set in S16 is equal to S7.
Control target speed V _T3 set by (see the diagram in FIG. 8)
The speed becomes closer to the driven wheel speed V _F (see the diagram in FIG. 8), so that the start timing of the traction control control is advanced and the slight slip generated in the left and right rear wheels 7, 8 can be promptly prevented. it can.

As described above, by setting the control target speed V _T3 ′ as in the above equation (3), the slip ratio is smaller than that in the case where the normal traction control is performed. ) To start the traction control.

When the control target speed V _T3 ′ is set in S16, the above-described processing in S8 and S9 is executed, and the drive wheel speed V _R (see the diagram in FIG. 8) becomes the control target speed V _T3 ′.
Execute the traction control control so that That is, a control signal is output to the drive motor 46 to output the sub-throttle valve 4
4 is closed to prevent the occurrence of slight slippage of the left and right rear wheels 7, 8. Then, when the slight slippage of the left and right rear wheels 7, 8 disappears, it is determined that the traction control control has been completed, and the process returns to S1.

The vehicle of this embodiment has the acceleration slip control device 1 including the anti-skid control hydraulic circuit 12 and the acceleration slip control hydraulic circuit 13 described above. The first solenoid valve 18 is excited to switch to the shut-off state, and the acceleration slip control displacement control valve 20 is operated as described above (1).
The brake hydraulic chamber 20 changes to the four states (1) to (14).
The hydraulic pressure of e is supplied to the left and right rear wheel cylinders 9, 10. Therefore, the left and right rear wheel cylinders 9 and 10
The inside pressure is increased (11), gradually increased (12), gradually reduced (13), or gradually reduced (14) to prevent the left and right rear wheels 7, 8 from slipping.

In S10 described above, V _R ≤V _F + α
Judges that substantially equal slip of the left and right rear wheel 7, 8 driving wheel speed V _R is the driven wheel speed V _F is close to zero, the process proceeds to step S17 when the. Accordingly, in S17, since the left and right rear wheels 7, 8 are not slipping, the timer T for measuring the time during which the slight slip occurs is reset to zero. continue,
Proceeding to S18, the integrated value A of the minute slip counter for integrating the minute slip occurrence amount is reset to zero.

As described above, the minute slip occurs in the left and right rear wheels 7 and 8 as the driving wheels, and the minute slip occurrence time T reaches the set time T ₀ (T> T ₀ ) or the minute slip occurs. When the integrated value A of the application counter reaches the reference integrated value A ₀ (A> A ₀ ), a new control target speed V _T3 ′
, The driving force transmitted to the left and right rear wheels 7, 8 can be reduced to prevent the occurrence of slip, so that the stability of the vehicle can be ensured, for example, on a wet road surface where a slight slip easily occurs. It can run stably on roads and slopes.

In the above embodiment, the traction control is performed when one of the conditions of the minute slip occurrence time T and the integrated value A of the minute slip occurrence amount is satisfied. However, the present invention is not limited to this, and it is a matter of course that the occurrence of the minute slip may be determined by checking only one of the conditions of the minute slip occurrence time T and the integrated value A of the minute slip occurrence amount from the beginning.

[0066]

As described above, according to the first aspect of the present invention, the driven wheel and the driving wheel are determined by the first slip determining means.
No excessive slip has occurred based on the speed difference with
The occurrence of a minute slip is determined and the second slip
When the speed difference occurrence time exceeds a predetermined time by another means
At the same time, it is determined that a slight slip has occurred in the drive wheel, and the drive force control means controls the drive force transmitted to the drive wheel to decrease so as to prevent the occurrence of a minute slip in the drive wheel. For example, the vehicle can run stably on a wet road surface or a sloping road where a slight slip easily occurs. Also, the speed between the driven wheel and the drive wheel
If an excessive slip has occurred based on the difference,
Driving force without performing the discriminating process by the slip discriminating means 2
The control means reduces the driving force transmitted to the driving wheels.
, And the occurrence of excessive slip can be prevented.

According to the second aspect of the present invention, the first slot is provided.
Based on the speed difference between the driven wheel and the drive wheel
No excessive slip has occurred, and
When occurrence is determined, the slip occurrence amount calculating means
From the speed difference between the driven wheel and the drive wheel,
The slip amount is calculated, the slip amount is integrated, and the drive wheel slip is calculated.
The sum of the lip generation amounts is calculated, and the sum of the slip generation amounts is
When it is equal to or more than the predetermined value, the second slip determination means
In order to determine that a slight slip has occurred in the drive wheels and to control the drive force control means to reduce the drive force transmitted to the drive wheels, the control is started in the same manner as in the first aspect of the present invention. The timing can be advanced to prevent the occurrence of minute slippage of the driving wheels, and, for example, stable running can be achieved even on a wet road surface or a sloping road where minute slippage is likely to occur. Also, based on the speed difference between the driven wheel and the drive wheel,
If an excessive slip has occurred, the second slip
Drive force control means without performing the discrimination processing by the
Control to reduce the driving force transmitted to the driving wheels
And the occurrence of excessive slip can be prevented.

[Brief description of the drawings]

FIG. 1 is a diagram showing the principle of the invention of claim 1;

FIG. 2 is a principle diagram of the invention according to claim 2;

FIG. 3 is a schematic configuration diagram of a wheel slip control device according to the present invention.

FIG. 4 is a block diagram of a wheel slip control device.

FIG. 5 is a flowchart illustrating a process executed by a CPU.

FIG. 6 is a graph for explaining a control start reference based on a slip occurrence time.

FIG. 7 is a graph for explaining a control start criterion based on a slip generation amount.

FIG. 8 is a graph for explaining a change in a control reference speed set by a process executed by a CPU.

FIG. 9 is a graph for explaining a conventional control start criterion.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Acceleration slip control device 2 Brake master cylinder 3, 4 Front wheel 5, 6, 9, 10 Wheel cylinder 7, 8 Rear wheel 12 Anti-skid control hydraulic circuit 13 Acceleration slip control hydraulic circuit 18 First solenoid valve 20 Acceleration slip control Capacity control valve 21 second solenoid valve 22 third solenoid valve 35 right front wheel rotation speed sensor 36 left front wheel rotation speed sensor 37 rear wheel rotation speed sensor 40 acceleration slip control circuit 40a CPU 44 sub throttle valve 48 accelerator pedal 49 main throttle valve

Continuation of front page (56) References JP-A-62-15125 (JP, A) JP-A-4-126636 (JP, A) JP-A-5-163972 (JP, A) JP-A-5-634 (JP) JP-A-4-292253 (JP, A) JP-A-63-259131 (JP, A) JP-A-63-20253 (JP, A) JP-A-4-328035 (JP, A) 1-269624 (JP, A) JP-A-1-113665 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B60K 41/20 F02D 29/02 311

Claims (2)

(57) [Claims] 1. A wheel speed detector for detecting a rotational speed of each wheel.
Output means, and the speed of the driven wheel detected by the wheel speed detection means.
The wheel that compares the control start reference speed with the drive wheel speed
Speed comparing means, and the driven wheel and the driving wheel by the wheel speed comparing means.
When it is detected that a speed difference has occurred, the speed
A timing means for timing the difference occurrence time,Excessive based on the speed difference between the driven wheel and the drive wheel
A first switch for determining the presence or absence of slip or minute slip
Lip determining means, The first slip discriminating means generates a slight slip.
When determined, said Speed difference timed by timing means
The presence or absence of occurrence of slip is determined based on the occurrence time, and the speed is determined.
Slip occurs when the time difference occurrence time exceeds the specified time
JudgeSecondSlip determining means;The occurrence of excessive slip is determined by the first slip determination means.
When it is determined, or the second For slip determination means
When it is determined that slippage has occurred, the power is transmitted to the drive wheels.
Driving force control hand that controls to reduce the reached driving force
A wheel slip control device, comprising: a step; 2. A wheel speed detection for detecting a rotation speed of each wheel.
Output means, and the speed of the driven wheel detected by the wheel speed detection means.
The wheel that compares the control start reference speed with the drive wheel speed
Speed comparison means;Excessive based on the speed difference between the driven wheel and the drive wheel
A first switch for determining the presence or absence of slip or minute slip
Lip determining means, The first slip discriminating means generates a slight slip.
When determined, the speed of the driven wheel and the drive wheel
The slip amount of the drive wheel is calculated from the difference, and the slip amount is calculated.
Integrate the quantity Slip for calculating the sum of slip occurrences
Generation amount calculation means; and a slip generation calculated by the slip generation amount calculation means.
Determine the presence or absence of slip based on the total amount of raw
When the total amount of slip generation exceeds a predetermined value, the slip
Judge thatSecondSlip determining means;The occurrence of excessive slip is determined by the first slip determination means.
When judged, again Is the second For slip determination means
When it is determined that slippage has occurred, the power is transmitted to the drive wheels.
Driving force control hand that controls to reduce the reached driving force
A wheel slip control device, comprising: a step;