JPS6215126A - Traction controlling device for vehicle - Google Patents

Abstract

PURPOSE:To enhance the starting performance with the provision of the improved control stability at a high speed by providing a vehicle with a vehicle start sensing means, a means which measures the time elapsed from the start of the vehicle, and a threshold level changing means which changes a set threshold depending on the time elapsed. CONSTITUTION:A set threshold level is changed by a threshold level changing means 60 depending on the time elapsed which is measured by a time counting means 61 since the time, which is detected by a start sensing means 11, when a vehicle has started. Accordingly, the threshold level can be set in such a way that the sensitivity for detecting a wheel spin is made dull shortly after the start of the vehicle so as to hardly effect the traction control, and later on with the elapse of time, the threshold level can be changed in such a way that the sensitivity for detecting the wheel spin is made sharp so as to effect the traction control with ease. Accordingly, this configuration allows the decrease in power, which is common to the plural number of driving wheels, to be delayed shortly after the start of the vehicle enabling the starting performance to be enhanced because the start had been made possible during the period of the said delayed time. Since then, the traction control is quickly effected with the elapse of time where the wheel spin is not permitted to take place, and the stability at a high speed can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a traction control device for preventing wheel spin in a vehicle having multiple drive wheels.

(Prior Art) Conventionally, this type of traction control device compares rotational information such as the wheels (circumferential speed) and acceleration of the plurality of drive wheels with a set value to determine the presence or absence of wheel spin. There is a system that prevents wheel spin by reducing the power common to multiple drive wheels when it occurs (
(such as that described in Japanese Patent Application Laid-open No. 49-61590).

(Problem to be solved by the invention) However, in this type of traction control device, common power is transmitted to each drive wheel under distribution by front and rear differential gears, and wheels can spin individually. Wheel spin alone reduces the common power, making the vehicle unable to start due to wheel spin of only one driven wheel.

In order to solve this problem, it is possible to prevent the above-mentioned traction control from being executed when the wheel spin of one driving wheel occurs. When wheel spin occurs in the rear wheels, it may cause a shudder phenomenon, and when wheel spin occurs in the front wheels, it may cause unstable steering.

(Means for Solving the Problem) From this point of view, the present invention improves starting performance by setting the above-mentioned threshold value so that traction control is difficult to perform at the beginning of starting, and traction control becomes more difficult as time elapses after starting. Based on the idea that it would be better to increase steering stability by setting the vehicle so that it is easy to move, the system includes a start detection means that detects the start of the vehicle based on the vehicle speed, a timing means that measures the elapsed time from the start, and a timer that measures the time elapsed since the start of the vehicle. The present invention is characterized by a configuration including threshold value changing means for changing the set threshold value according to time.

(Function) In such a configuration, when wheel spin occurs, which is determined by comparison with a set threshold value based on rotation information of multiple drive wheels,
In reducing the power common to the plurality of driving wheels, the threshold value changing means changes the set threshold according to the elapsed time detected by the start detecting means and measured by the timer means after the start.

Therefore, the threshold value is set so that the wheel spin detection sensitivity is dull at the beginning of the vehicle, making it difficult to perform traction control, and then as time passes, the threshold value is set so that the wheel spin detection sensitivity becomes sharper, making it easier to perform traction control. It becomes possible to change the set threshold value, such as by determining the threshold value. Therefore, at the beginning of the start, traction control, that is, the reduction of the common power described above, is delayed, and while it is possible to start during this time and improve starting performance, after that, as time passes, traction control is quickly executed and the wheels spin. This allows for improved handling stability at high vehicle speeds.

(Example)' Hereinafter, the present invention will be described in detail based on illustrated embodiments.

Figure 1 shows an embodiment of the traction control device of the present invention applied to a four-wheel drive vehicle. In the figure, IL and IR are left and right front wheels, 2L and 2R are left and right rear wheels, and 4 provides common power to all these wheels. 5 is a transmission, 7 is a transfer, 8 is a front wheel differential gear, and 9 is a rear wheel differential gear. The power from the engine 4 is input to the transfer 7 via the transmission 5, and is then distributed to the differential gear 8.9.
By distributing the input power to the differential gear 8 to the left and right front wheels IL and IR, and by distributing the input power to the left and right rear wheels 2L and 2R by the differential gear 9, the vehicle is driven by four-wheel drive. Run.

The power of the engine 4 is adjusted by a throttle valve 42, which is shown separately from the engine 4 for convenience in the figure, and due to the decrease in power (in this example, a decrease in the opening degree of the throttle valve 420), traction control is performed as described later. In order to do this, the throttle valve 42 is not mechanically linked to the accelerator pedal 43 as in the prior art, but is electronically controlled by the following configuration.

That is, the throttle valve shirt) 42a has a reducer 44.
A motor 45 is connected for driving through the motor, and the motor increases the throttle opening as shown in FIG. 3 in proportion to the amount of forward rotation, and decreases the throttle opening in the same direction during reverse rotation. Both terminals of the motor 45 are connected to the power supply element E via an interlocking relay 46 and a relay 47, and while the relay 47 is open due to deenergization of the solenoid 47a, the motor 45 is stopped, and the relay 47 is energized to the solenoid 47a. If the contacts of the relay 46 are in the fixed line position while closed, the motor 45 rotates in the normal direction, and if the contacts of the relay 46 are in the dotted line position, the motor 45 rotates normally.
shall be reversed. It is assumed that the contact point of the relay 46 is at the solid line position when the solenoid 46a is de-energized and at the line position when the solenoid 46a is energized.

Each of the relay solenoids 46a and 47a has one end connected to the power supply terminal 0, and the other end connected to ground through collector emitter paths of transistors 48 and 49. The base of transistor 48 is connected to power supply element E via the collector-emitter path of transistor 50 and to the output of comparator 51. The base of the transistor 49 is connected to the power supply E through the collector-emitter path of the transistor 52 on the negative side and to ground through the collector-emitter path of the transistor 53, and is connected to the output of the NAND gate 54 on the other side. A comparator 51 for each of the two NAND gates 54
．． 55, and manually input a signal relating to the opening degree of the throttle valve 42 (throttle opening degree) and a signal relating to the depression amount of the accelerator pedal 43 to these comparators as shown below. - A low-return encoder 56 is provided on the throttle valve shirt 42a to detect its rotational position, and based on the signal from this, a throttle opening detection circuit 57 increases the rotational position (throttle opening) of the throttle valve shirt) 42a. Generate voltage TH. This voltage is the resistance R
,, R2 divides the voltage, and the diode D1 installed between these resistors causes a difference in the voltages generated at points d and e before and after the resistor, which is equivalent to the voltage drop of the diode D, between the two voltages as shown in Fig. 4. Set the dead zone shown with hatching. Further, an accelerator opening sensor 58 is provided which is linked to the accelerator pedal 43 and generates a voltage ACC which increases in proportion to the amount of pedal depression.The voltage ACC is divided by resistors R3 and R4. A comparator 51 calculates the voltage at point f between these resistors.
．． 55, and the voltages at the points d and e are applied to the other inputs of the comparators 51 and 55, respectively.

The transistors 50, 52, and 53 are used for traction control to maintain or forcibly reduce the throttle opening (engine power 9) at the current value regardless of the amount of accelerator pedal depression. 52 and 53 are controlled by the outputs of AND gates 3 and 14 connected to their respective bases.The output of AND gate 13 is connected to the base of transistor 530, and the output of AND gate 14 is connected to the base of transistor 50 and 52
The manual power of these gates will be explained in detail later, and first the operation of the throttle opening control system will be explained.

As will be described later, while traction control is not executed, the output of gate 13.14 is at L level, transistors 50, 52, and 53 are all turned off, and transistors 48.49 are turned on and off by comparator 51 and N.
It is controlled by the output of the AND gate 54, and during this time, normal throttle opening control is executed as described below to make the opening of the throttle valve 42 correspond to the amount of depression of the accelerator pedal 43. That is, if the driver operates the accelerator pedal 43 so that the voltage ACC changes as shown in FIG. 4, the voltage at point f changes accordingly. During such accelerator operation, the voltage at point d corresponding to the throttle opening is at instant t in FIG. -1, between f
While the voltage is lower than the voltage at the point (while the throttle opening is less than the value equivalent to the accelerator pedal depression), the output of the comparator 51 is at the L level and the output of the comparator 55 is at the H level, so the transistor 48 is non-conducting. , the transistor 49 becomes conductive.

At this time, the relay 47 is closed and the contact point of the relay 46 is at the solid line position, so the motor 45 rotates in the normal direction, and the throttle opening increases to a value equivalent to the amount of accelerator pedal depression, as is clear from the change in voltage TH. let

As a result, the voltage at point d matches the voltage at point f at the fourth T.
During sA, from instant t1 to instant t2 in FIG. 4 when the voltage at point f drops to the voltage at point e, that is, while the throttle opening has settled down to a value equivalent to the amount of accelerator pedal depression, the comparator 51 is Since the comparator 55 changes the output to the H level and keeps the output at the H level, the NANO gate 54 changes the output to the L level and opens the relay 47 by making the transistor 49 non-conductive. At this time, the motor 45 is stopped and the throttle opening degree is maintained at the current value as is clear from the change in voltage TH.

Between instants t2 and t3 in FIG. 4 when the voltage at point f becomes equal to or less than the voltage at point e due to a decrease in the amount of depression of the accelerator pedal 43, that is, while the throttle opening is equal to or greater than the value equivalent to the amount of depression of the accelerator pedal, the comparator Although 51 keeps the output at H level,
Since the comparator 55 changes the output to the L level, the NANO gate 54 closes the relay 47 by conducting the transistor 49, and the comparator 51 sets the contact point of the relay 46 to the dotted line position. At this time, the motor 45 rotates in reverse, and the throttle opening is controlled by the voltage T.
As is clear from the change in H, the direction is decreased to a value equivalent to the amount of depression of the accelerator pedal.

As a result, from instant t3 in FIG. 4, when the voltage at point e matches the voltage at point f, to instant t4 when the voltage at point f is within the voltage at point d, that is, the throttle opening changes when the accelerator pedal is depressed. While the amount has settled down to the equivalent value, the instant t1 to t
During the second interval, the motor 45 is stopped in the same manner as described above, and the throttle opening is maintained at the current value.

As a result of the above action, the throttle opening is brought to a value equivalent to the amount of depression of the accelerator pedal, and the output of the engine can be controlled by the accelerator pedal 43 as usual.

By the way, at instant t in FIG. 4, the accelerator pedal 43 is depressed and the voltage ACC and the voltage at point f are accelerated as shown in the figure, causing wheel spin, and as will be described later, at instant t... During t3, the output of gate 13 becomes H level, the output of gate H4 becomes L level, and after instant t5, the output of gate 13 becomes L level, and the output of Lehenope gate 14 becomes H level. Throttle opening control during traction control is as follows. It is done as follows.

That is, at instants t, to t, the output of the gate 13 is at H level, so that the transistor 53 is made conductive, the transistor 49 is made non-conductive, and the relay 47 is turned off.
do. Therefore, even if the voltage at point f exceeds the voltage at point d as shown in FIG. 4, the motor 45 is kept in a stopped state, and the throttle opening is maintained at the current value as seen from the change in voltage TH. Therefore, the engine power is maintained at the current value, as requested, despite depression of the accelerator pedal 43. After the instant t5, the output of the gate 13 and the output of the L lechenope gate 14 are at the H level, so that the transistor 53 is rendered non-conductive and the transistors 50 and 52 are rendered conductive. ON1 of transistor 52
When the transistor 53 is turned off, the transistor 49 is turned on regardless of the output of the NAN log gate 54, and the relay 47 is closed. When the transistor 50 is turned on, the transistor 48 is turned on regardless of the output of the comparator 51, and the relay 46 is placed in the dotted line state. Thus, the motor 45 is reversed and the throttle opening is reduced despite the depression of the accelerator pedal, as is clear from the change in voltage TH in FIG. 4, reducing engine power and preventing wheelspin. can do.

Next, to explain the human power of AND gates 13 and 14, one man power of gates 13 and 14 requires OR gate 15 and A, respectively.
Connect the output of ND game) 16. [The output of the AND gate 17 is connected to the single power of JR Agate 5, and the output of the comparator 18 is connected to the other power of OR Age-15. AN
The D gate 17 performs a logical product between the L level output of the AND gate 16 and the H level output of the comparator 19, and the AND gate 16 performs a logical product between the L level output of the comparator 18 and the H level output of the comparator 20. shall be taken.

Rotation sensors 21a and 21b that detect the rotation speeds of the right front wheel IR and left front wheel 1, and rotation sensors 21c and 21d that detect the rotation speeds of the right rear wheel 2R and left rear wheel 2L are provided, and wheel rotations from these are provided. Pulse signals with frequencies corresponding to the numbers are input to wheel speed calculation circuits 22a to 22d, respectively.

Each of these circuits determines the peripheral speed (wheel speed) of the corresponding wheel based on the frequency of the input pulse signal and the rotation radius of the corresponding wheel.
Vw, ˜Vw, are calculated.

These wheel speeds are input to a select low switch 10 which is also a vehicle speed detection means, and this select low switch 10 selects the lowest value among the wheel speeds Vw and xVw as the minimum wheel speed value Vw. Since this is the wheel speed closest to
2R and 2L are also input to the wheel acceleration calculation circuit 23 and the subtractor 24 as wheel rotation information for executing traction control when the wheels are in a state where the wheels spin.

The circuit 23 calculates the wheel acceleration Vw from the minimum wheel speed value Vw, and inputs the result to the comparators 18 and 19. Comparator 1
8 outputs the H level when the wheel deceleration Vw exceeds the deceleration reference value (threshold value) -b, and the comparator 19 outputs the H level when the wheel deceleration Vw exceeds the deceleration reference value (threshold value) -b.
It is assumed that the H level is output when w exceeds the acceleration reference value (threshold value) +4.

The pseudo vehicle speed generating circuit 25 generates a vehicle speed expected after wheelspin as a pseudo vehicle speed vK as described later, since the wheel speed does not simulate the vehicle speed when the minimum wheel speed value Vw indicates wheel spin. , which is supplied to the select low switch 12.

As will be clear from what will be described later, the lower of the minimum wheel speed value Vw and the pseudo vehicle speed Vi is closer to the vehicle speed, so the select low switch 12 selects the lower one as the vehicle speed equivalent value Viw.
, and manually input it to the comparator 20.

The subtractor 24 calculates the allowable spin amount △Vw from the minimum wheel speed value Vw.
is subtracted, and the result Vw-ΔVw is input to the comparator 20. The comparator 20 compares the calculated value Vw-△Vw of the subtractor 24 and the vehicle speed equivalent value Viw, and determines that vIll-△vIIl≧v
IW, Tsumari VW≧Viw +△Vw (Viw+△V
When v is a threshold value), the output is set to H level.

In the present invention, threshold values -b, +a, Viw +△V
In order to change w in accordance with the elapsed time after starting, a threshold value changing means 60 is provided, and this means has the following configuration in this example. That is, the comparator 11 is used as a start detection means,
This comparator uses the minimum wheel speed value Vw as vehicle speed information, and outputs an H level after the vehicle starts when this value becomes equal to or higher than the set vehicle speed Vs. The set vehicle speed Vs is set near the lower limit value of the vehicle speed corresponding to the wheel speed that can be detected by the rotation sensors 21a to 21d and the wheel speed calculation circuits 22a to 22d. The output of the comparator 11 is connected to the input of the AND gates 13 and 14, and is also connected to the human power of retriggerable timers 61 to 63, and these timers are set in synchronization with the rise of the human power (starting when Vw≧Vs). Pulse width ΔTl+ ΔT2. A negative polarity pulse signal of ΔT3 is output.

The pulse width of the negative pulse signal from the timer 61 is T1, and the pulse width of the negative pulse signal from the timer 62 is T2.
and the pulse width △T of the negative pulse signal from the timer 63
3, the relationship △T, < 8T2 < △T3 is established, so that the timers 61 to 63 are used as a time measuring means for measuring the elapsed time after starting the vehicle, and these timers 61 to 63
Gates 64 to 67 are provided which determine the levels of select signals S and -S4 based on the combination of outputs (elapsed time after starting).

AND gate 64 logically ANDs the H level outputs from timers 61 to 63 to set select signal SI to H level,
AND gate 65 logically ANDs the H level output of timers 61 and 62 and the L level output of timer 63 to set select signal S2 to H level, and AND gate 66 connects tie 761.
(7) Take the AND of the H level output and the L level output of timers 62 and 63 to set the select signal S3 to H level,
ljA N D gate 67 logically ANDs the L level outputs of timers 61 to 63 and sets the select signal S to H level. Thus, the H level of the select signal S1 indicates that more than T3 hours have passed since the start, and the H level of the select signal S2 indicates that less than ΔT1 hours and more than 612 hours have passed since the start. H level represents the passage of time less than 612 hours, △T, or more than 612 hours after the start,
The H level of the select signal S4 indicates that 611 hours have passed since the start of the vehicle.

After the gates 64 to 67, analog switches 68b to
68d, 69a ~ 69d, 7Qa ~ 70d
and analog switches 68a, 69a, 70
A is an analog switch 68b which is turned on while the select signal S1 is at H level.

59b and 70b are O while the select signal S2 is at H level.
N, analog switches 68c, 69c, 70c
- is turned on while the select signal S3 is at H level, and is the analog switch 68d.

69d and 70d are O while the select signal S4 is at H level.
It shall be N. Switches 68a to 68d are each set to O.
N time ΔVw, ~△vI114 is selectively input to the subtracter 24 as the allowable spin amount △Vw, and these △Vw, ~△V
Between w4, △Vwa > △Vw3 > △Vw2 as shown in Figure 5
>△Vw+0) relationship. Switches 698-69
d is selectively inputted to the comparator 19 and the pseudo vehicle speed generation circuit 25 as the acceleration reference value +a when turned ON, and between these 1a and +a1 as shown in FIG.
＞+a3＞+a2＞+a.

have a relationship of Also, the switches 70a to 70d are each set to O.
The comparator 1 is set to the deceleration reference value at N time -b1 to -b.
8, and create the relationships between -b1 to -b9 as shown in FIG. 5: <b, >b, >b2>b.

FIG. 2 shows a specific example of the pseudo vehicle speed generation circuit 25, which includes a sample hold circuit 26, a wheel acceleration calculation circuit 27, a comparator 28, a differentiation circuit 29, a monostable multi-bi break 30, and a constant setting. 31 and an integrating circuit 32
, an adder circuit 33, OR gates 34, 35, and inverters 36, 37 are connected as shown in the figure.

The sample hold circuit 26 is a select low switch 10
The lowest wheel speed value Vw selected by is inputted, the wheel speed Vw (0) when the switching transistor 26a is turned on by the shot pulse is sampled and held, and this is inputted to the addition circuit 33. Wheel acceleration calculation circuit 27
calculates the wheel acceleration Vw from the minimum wheel speed value Vw, and the comparator 28 compares this with the acceleration reference value +a to find that Vw>
When +a, an H level signal is output. The differentiating circuit 29 emits a shot pulse in synchronization with the rise of this signal, and the monostable multi-by-break 30 outputs an H level signal for a set time. Integrating circuit 32 is switching transistor 3
It is cleared when 2a is turned ON by the input of an H level signal, and otherwise it integrates the constant value -m from the constant setter 31 and inputs the integrated values mJ and dt to the adder circuit 33.

The addition circuit 33 calculates the wheel speed sampling value Vw (0)
The pseudo vehicle speed Vi is obtained by adding the integral value m,/,'dt to

In such a configuration, when the minimum wheel speed value Vw and its wheel acceleration Vw are as shown in FIG. 6 (vehicle speed Vc is also shown for reference), the pseudo vehicle speed Vi is determined as follows.

Note that in reality, the acceleration reference value +a changes between +a1 and +a4 (see Figure 1), but to make the explanation easier to understand, the following will be written assuming that the acceleration reference value +a is constant as shown in Figure 6. I will explain the following. That is, between instants t1 and t2 and t when the wheel acceleration Vw becomes equal to or higher than the reference value +8.
3 to t9, the comparator 28 sets its output to H level. In synchronization with the rise of the output, the monostable multi-bi break 30 outputs an H level signal for a set time ΔT as shown in FIG. , the monostable multi-bi break 30 again outputs an H level signal for a time ΔT, and at an instant t after this ΔT time, the monostable multi-bi break 30 changes its output to an L level. The output of the monostable multi-bi break 30 is inverted by inverters 36 and 37 as shown in FIG. 6, and is input to the OR3L35.

The moment when the wheel acceleration Vw exceeds the reference value +a and the output of the comparator 28 rises 1. ．． 1. Then, the differentiating circuit 29 outputs a shot pulse as shown in FIG.
Enter in 34 and 35. Since the OR gates 34 and 35 are supplied with the above-mentioned inverted outputs, the switching transistors 26a and 35 are switched by the above-mentioned shot pulse.
32a temporarily ONL, instantaneous t1. The minimum wheel speed value Vw at this time is input to the t3 sample hold circuit 26.
(0), and integrate circuit 3.
2 and restart the integration. Vw (0) is instantaneous 1. as shown in FIG. ．． 13 wheel speed sampling values, and the integral value nJ:dt of the integrating circuit is the instantaneous tInt.
It is the change in expected vehicle speed with the time gradient from 3 as m,
Added value Vw (0) +m of the circuit 33 that adds these
/'dt, instantaneous 1. ．． The pseudo vehicle speed Vi expected from 13 onwards can be determined as shown in FIG. In addition,
The time gradient m can be arbitrarily set using the constant setter 31. If the next output of the comparator 28 does not rise within 61 hours, the outputs of the inverters 36 and 37 will maintain the H level as after instant t5 in FIG.
w(0)=Vw, m,/' dt=Q, so that the pseudo vehicle speed Vi becomes the same as the minimum wheel speed value Vw.

Here, in the case where each wheel speed Vw, ~Vw4 changes as shown in the upper part of FIG. 7 (however, Vw2=Vw, and Vc
(vehicle speed shown for reference) In particular, the select low switch 10 in FIG.
Select the one closest to c as shown in the center of the figure,
Based on this, the pseudo vehicle speed generating circuit 25 generates the pseudo vehicle speed Vi as described above with reference to FIGS. 2 and 6 (however, while the pseudo vehicle speed Vi is not generated, as described above (Vi=Vw). In Figure 1, the select low switch 12 is the pseudo vehicle speed v1.
and the lowest wheel speed value Vw is selected as the vehicle speed equivalent value Viw corresponding to the vehicle speed Vc, as shown in the lower part of FIG.
This is supplied to the comparator 20.

The operation of the above-mentioned embodiment will now be described in the case where the minimum wheel speed value Vw and the wheel acceleration Vw are as shown in FIG. Note that here too, the acceleration reference value +a is actually +a, ~+a
4 (see Figure 1), and the deceleration reference value -b is -b1~
- 9 (see Figure 1), and the allowable spin amount △Vw changes between △Vw and △Vw4 (see Figure 1), but for convenience of explanation, the following explanation assumes that these are constant. Let's do it.

The pseudo vehicle speed generation circuit 25 operates at the moment 1. when the wheel acceleration Vw exceeds the acceleration reference value +a. , 13.11.1. Creates a pseudo vehicle speed Vi for 61 hours every time, select low switch 1
2 supplies the lower of the pseudo vehicle speed Vi and the minimum wheel speed value Vw to the comparator 20 as a vehicle speed equivalent value 'Viw. As described above, the comparator 20 operates between instants t4 and t5 and t when the minimum wheel speed value Vw becomes equal to or higher than viw+Δ%1w shown in FIG.
l.

Between t12 and t12, the output is set to H level as shown in the figure.

On the other hand, the comparator 18 indicates that the wheel deceleration Vw is the deceleration reference value - b
The comparator 19 sets the output to H level between the instants t and t6 when the wheel acceleration exceeds the acceleration reference value +a, and after t11.
The output is set to H level between 7 and t8, between t, and t, and '.

Further, depending on the outputs of the comparators 18-20, the levels of the outputs of the OR gate 15 and the AND gate 16 change as shown in FIG. 8, respectively.

Incidentally, the comparator 11 maintains its output at L level until instant t0 in FIG. 8, when starting is detected due to Vw≧Vs.

Therefore, the AND game (13.14) is prohibited from outputting an H level, and the transistors 50, 52, and 53 are turned off to make the throttle opening (engine power) correspond to the amount of depression of the accelerator pedal 43, as described above.

Therefore, in a state where the rotation sensors 21a to 21C and the wheel speed calculation circuits 22a to 22C cannot detect the wheel speeds vw, to Vw4 (Vw < Vs), the gate 15.16
In order to prevent traction control from malfunctioning due to an erroneous signal from the vehicle, traction control can be inhibited.

Start instant t in FIG. 8 at which Vw≧Vs. From now on, comparator 11
Converts the output to H level, AND game) 13.H level output from 14, that is, enables Titraction control. However, until time t1 in FIG. 8 when the wheel acceleration Vw exceeds the reference value +a for the first time, the OR gate 15 and the AND
Since the outputs of the gates 16 are both at the L level, the outputs of the AND gates 13 and 14 are also at the L level, and the transistors 50, 52, and 53 all remain OFF. Therefore, the throttle opening is determined by the transistor 4 as described above.
The engine power is controlled as usual to be linked to the accelerator pedal 43 through ON and OFF of 8.49.
As shown in the figure, it increases to follow the accelerator operation.

By the way, moment 1. When Vw≧rice, the output of the OR gate 15 changes to the H level, so the output of the AND gate 13 also changes to the H level, and the throttle opening (engine power) is maintained at the value at this time as described above. During this time, check whether the wheel spin is certain or not.

However, when it returns to VW<+a at instant t2, wheel spin is not certain, so next OW≧+a
Until the instant t3, OR Age-15 (AND gate 13
) is returned to the L level, and the throttle opening (engine power) is increased to correspond to the amount of accelerator pedal depression. After the instant t3 when l/w≧+a, the throttle opening (engine power) is maintained by the H level output of the OR gate 15 (AND gate 13) again as described above, and it is confirmed whether the wheel spin is certain. .

Then, when Vw≧Viw+△Vw at instant t4, wheel spin is certain.
3) to L level, and the output of AND gate 16,
Therefore, the output of AND gate 14 is set to H level. As a result, the throttle opening (engine power) is reduced despite depression of the accelerator pedal as described above, and wheel spin can be prevented.

At the instant t5 when the wheel deceleration Ow exceeds the reference value -b due to the decrease in the minimum wheel speed value Vw, it is assumed that the wheel spin has disappeared, and OR Age-15 (AND gate 13)
The output of AND gate 16 (A
Since the output of the ND gate 14) changes to L level,
The throttle opening (engine power) is maintained at the current value. Thereafter, the instant t when the wheel deceleration Vw becomes equal to or less than the reference value -b
After 6, the output of the OR gate 15 (AND gate 13) changes to the L level, so the output of the AND gate 16 (AND'7
The throttle opening (engine power) is increased in conjunction with the L level output maintenance in step 14).

The above cycle is repeated after the instant t7 when the wheel acceleration exceeds the reference value +a, and the engine power is eventually maintained at its maximum in relation to the traction limit shown by TL in Figure 8, causing the vehicle to avoid wheelspin. On the other hand, it is possible to run the vehicle without restricting the engine power more than necessary.

Incidentally, the starting instant t in FIG. 8 is when the output of the comparator 11 rises. In synchronization with , the retriggerable timers 61 to 63 have pulse widths △Tl+ △t2+ △T, respectively, as shown in the figure.
3 negative polarity pulse signal is emitted. During the period △T after starting when the outputs of timers 61 to 63 are all at L level,
The gate 67 sets the select signal S to the H level, and then the gate 66 sets the select signal S3 to the H level until the output of the timer 62 changes to the H level, and then the output of the timer 63 changes to the H level. Until then, the gate 65 sets the select signal S2 to H level, and after that, the gate 64
keeps the select signal S at H level.

Therefore, during the ΔT+ time at the beginning of the start, the analog switches 68d, 69d, 70 are activated by the H level select signal S4.
d is ONL, allowable spin amount △Vw is △VW4, acceleration reference value +a is +a4, deceleration reference value -b is -b4
Nasu. After that, the analog switches 68c, 69c, and 70c are turned ON and △ by the H level select signal S.
Vw=△Vw3. +a=+a3°-b=-b3, and the analog switch 6 is activated by the H level select signal S2.
8b, 69b, 70b mouth N, △Vw=△Vw2
．． +a=+a2. -b=-b2, and then H
The analog switch 68a is controlled by the level select signal S.
, 69a, 70a are ONL, △VW=△Vw,
, +a=+a, , -b=-b.

becomes. Thus, the allowable spin amount △Vw, acceleration reference value + a
and deceleration reference value -b will change as shown in Fig. 5 depending on the time elapsed from the advance, respectively, and the threshold values Viw + △Vw, +a, -b, which are used as criteria for determining wheel spin in the traction control described above, will be changed as shown in Fig. 5. The absolute value can be increased at the beginning of the vehicle and then decreased over time. Therefore, at the beginning of starting, the traction control sensitivity becomes dull, which makes it possible to delay the reduction of the power common to each drive wheel (power of the engine 4), and during this time, it is possible to start and improve the starting performance.

On the other hand, as time passes after the vehicle starts, the traction control sensitivity becomes sharper, and at high vehicle speeds after the vehicle starts, wheel spin is not tolerated at all, and unstable steering due to wheel spin can be prevented.

In the above example, when setting the allowable spin amount ΔVw, ΔVw, ~ΔVw4 are selectively used by the select signals S, ~S4, but the select signal Sl""S
4, the allowable slip rate is selected by multiplying the selected slip rate by the pseudo vehicle speed Vi from the circuit 25 as the allowable spin amount △Vw, or the allowable spin amount obtained in this way is added to the allowable spin amount for each S1 to S4. The result of correction by adding the fixed value can also be set as the final allowable spin amount ΔVw.

(Effects of the Invention) Thus, as described above, the traction control device of the present invention is configured to change the threshold value with which driving wheel rotation information is compared in determining wheel spin depending on the elapsed time after starting. For example, a set threshold value is determined so that the wheel spin detection sensitivity becomes dull so that traction control is difficult to perform, and then a set threshold value is determined so that the wheel spin detection sensitivity becomes sharper as time passes so that traction control becomes easier to perform. It becomes possible to change the set threshold value. Therefore, at the beginning of the start, traction control, that is, the reduction of the common power described above, is delayed, and while it is possible to start during this time and improve starting performance, after that, as time passes, traction control is quickly executed and the wheels spin. This allows for improved handling stability at high vehicle speeds.

[Brief explanation of drawings]

Fig. 1 is an overall system diagram showing one embodiment of the traction control device of the present invention, Fig. 2 is an electronic circuit diagram of a pseudo vehicle speed generation circuit in the same device, and Fig. 3 is a throttle opening diagram for normal rotation I of the motor in the same device. Figure 4 is a time chart showing voltage changes at each point in the throttle opening control system in the same device, Figure 5 is a threshold change characteristic diagram in the device shown in Figure 1, and Figure 6 is a time chart showing voltage changes at each point in the throttle opening control system of the device. 7 and 8 are operation time charts of the device shown in FIG. 1, respectively. IL, IR, 2L, 2R... Drive wheel 4...
Engine 5...Transmission 7...Transfer 8.9...Differential gear 10, 12...Select yaw switch 11...Comparator (start detection means) 13, 14...AND gate 15.・OR
Gate 16.17...AND gate 18-20
...Comparators 21a to 21d...Rotation sensors 22a to 22d...Wheel speed calculation circuit 23...Wheel acceleration calculation circuit 24...Subtractor 25
... Pseudo vehicle speed generation circuit 42 ... Throttle valve 43 ... Accelerator pedal 44 ... Reducer 45 ... Motor 46
, 47...Relays 48-50.52.53...Transistors 51.55
... Comparator 54 ... NANO gate 56
...Rotary encoder 5T...Throttle opening detection circuit 58...Accelerator opening sensor 60...Threshold value changing means 61 to 63...Retriggerable timer (timekeeping means)
64-66...AND gate 67...NAN
O gates 68a to 68d, 69a to 69d, 70a
~70d -Analog switch Figure 2 Figure 3 Mogel IT Drinking amount Figure 4 Figure 5 (-b)

Claims (1)

[Scope of Claims] 1. A vehicle that determines wheel spin by comparing rotation information of a plurality of drive wheels with a set threshold value, and reduces power common to the plurality of drive wheels when wheel spin occurs to prevent wheel spin. The traction control device includes a start detection means for detecting the start of the vehicle based on the vehicle speed, a timer means for measuring the elapsed time since the start, and a threshold value changing means for changing the set threshold according to the elapsed time. A vehicle traction control device characterized by: