JPS61285131A - Traction control device for vehicle - Google Patents

Abstract

PURPOSE:To enable traction control without need for using information on wheel speed on non-driving wheels by selecting the lowest value among the wheel speeds of plural driving wheels, and regarding a driving wheel the wheel speed of which is above a certain value with respect to this lowest value, as a spinning wheel. CONSTITUTION:A hydraulic multiple disc clutch 6 (subscripts omitted) is installed to the axle of each wheel and its clutch pressure can be adjusted by controlling a magnetic selector valve 10 by means of a control device. The control device has an operating circuits 22 for operating wheel speeds Vw from pulse signals from revolution sensors 21 attached to the axles and from the radii of gyration of wheels, an operating circuit 23 for operating wheel acceleration Vw' from the Vw, and a subtractor 24 which subtracts an allowable spinning quantity DELTAVw from the Vw. Also, a select low switch 38 which selects the lowest value among the wheel speeds Vw1 to Vw4 obtained by the operating circuits 22 respectively, is provided to detect the spinning of a wheel in accordance with the value of either the lowest value or a pseudo-car speed Vi whichever is the lower, by a comparator 20.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a traction control device h' that prevents wheel spin in a vehicle having a plurality of drive wheels.〇 (Prior art) Wheel spin is caused by This occurs when the torque transmitted to the drive wheels exceeds the road friction force, increasing power loss, making it difficult to start on low friction roads such as frozen roads, and causing skidding during acceleration.

Therefore, as previously disclosed in Japanese Patent Application Laid-Open No. 59-68587, the wheel speed of the non-driving wheels and the wheel speed of the driving wheels are compared, and if the latter wheel speed is higher than the former wheel speed, A technology has been proposed that determines that the drive wheels are spinning when the wheels spin, and reduces the torque 1 transmitted to the drive wheels.

(Problems to be Solved by the Invention) However, such traction control technology requires wheel speed detection means for non-driving wheels in addition to the driving wheels to be controlled, making the device expensive and prone to failure. In addition, in a full-width drive vehicle in which all wheels are driven, there are no non-driving wheels, so the wheel speed of the non-driving wheels is reduced as in conventional 1 above. It is not possible to employ a method of detecting the presence or absence of wheel spin by comparing the speed of the wheel and the wheel speed of the drive wheels.

(Means for solving the problem) The first aspect of the present invention is that in a vehicle having a plurality of drive wheels, it is rare for all of these drive wheels to spin at the same time, and most of the time there is a phase shift. Based on the fact that it is safe to regard the lowest value of the wheel speeds of multiple drive wheels as the value equivalent to the vehicle speed, a wheel speed detector for detecting the wheel speed of each drive wheel is installed. , ``A select low means is provided for selecting the lowest value among these wheel speeds, and a torque reduction means is provided for reducing the torque transmitted to the driving wheels whose wheel speed exceeds a predetermined value in comparison with the lowest value. By the way, such a traction control device is unable to detect if the driving wheels spin in synchronization, and the twenty-first invention of the present invention provides various measures to take measures against this. wheel speed detection means for detecting the wheel speed of the driving wheels; first select low means for selecting the lowest value among these wheel speeds; and creating one expected pseudo vehicle speed during wheelspin based on the lowest value. a pseudo vehicle speed generating means, a second select low means for selecting the lower of the minimum value and the pseudo vehicle speed, and a drive when the wheel speed becomes a predetermined value or more in comparison with the value selected by the second select low means. It is equipped with a torque reduction means for reducing the torque transmitted to the wheels.

(Action) In the first invention, select the lowest value of the wheel wheels detected by wheel speed detection means, and the torque decrease method is specified by the wheel speed in comparison with this lowest value. This reduces the torque transmitted to the drive wheels to prevent wheel spin of the drive wheels. Therefore, as is clear from the reasons mentioned above, the above minimum value can be regarded as a value equivalent to the vehicle speed (1), and the above comparison of this value with the wheel speed makes it possible to reliably detect the wheel spin of the driving wheels. Traction control can be performed accurately.

By the way, this traction control does not require the wheel speed of the non-driving wheels as information unlike conventional methods, so there is no need to provide wheel speed detection means for the non-driving wheels.
Therefore, the device can be constructed at a low cost, the occurrence of failures can be kept low, and it can also be applied to full-width drive vehicles that do not have non-drive wheels.

It is practical.

Further, in the second invention, the pseudo vehicle speed generating means generates a pseudo vehicle speed expected during wheelspin based on the minimum value selected by the first select low means, and the second select low means generates a pseudo vehicle speed expected during wheel spin. □ The lower one of the pseudo vehicle speeds is selected, and the torque reduction means reduces the torque transmitted to the drive wheel whose wheel speed exceeds a predetermined value in comparison with this selected value, thereby preventing wheelspin of the drive wheel.

By the way, this traffic control is the first (・1)
In addition to the above-mentioned effects of the invention, even if all of the drive wheels spin simultaneously, the wheel spin can be detected based on the pseudo vehicle speed, and traction control can be performed as prescribed.

(Example) Hereinafter, the present invention will be explained in detail based on the illustrated embodiment. The rear wheel, number 5 indicates the engine, and number 5 indicates the transmission. Hydraulic multi-plate clutches 6a to 6d are provided on the axles of each wheel so that the wheel drive torque can be controlled individually.0 Note that 7 is a center differential gear, 8 is a front wheel differential gear, and □ and 9 are rear wheels. When the clutches 6a to 6d are engaged, the power of the engine 4 is transmitted to the transmission 5 and the differential gears 7 to 7.
The signal is transmitted to all wheels via 9, allowing the vehicle to run with full width drive.

Clutches 6a to 6d have individual clutch pressures P. ,~P04
The fastening force (torque transmitted to the corresponding wheels) is controlled by
These clutch pressures are determined by individual control circuits. Note that since all the individual control circuits have the same configuration, the right front wheel I
Only □ related to R will be described in detail, and other control circuits are shown by giving the same reference numerals with different suffixes to corresponding parts in the drawings. In other words, clutch pressure P. , solenoid switching valve 1 to control
0a, and this valve has both solenoids lOa',・10
When power is reduced at a', the boat is placed in the center of the diagram, and constant 1 pressure valve 1
The oil from the oil pump 12, which has been regulated to a constant pressure in step 1, is supplied to the clutch 6a to set the clutch pressure P. , is increased to the same value as the above constant pressure, and when the solenoid 10a' is energized, the boat configuration shown in the upper side of the figure is achieved, and the clutch pressure P is increased. □ is held at the current value, and during the energization time of solenoid 10a', the boat is placed on the lower side, and the clutch pressure P. , is used as a spring center 2 8-position switching valve that drains and lowers the air. Solenoids 10a' and 10a' have one terminal connected to the t source 1110E, and the other terminal connected to the collectors of transistors 13a and 14a. Grounded through the emitter passage. The outputs of the OR gate 15a and the AND gate iaa are connected to the paces of the transistors 18a and 14a, respectively, and the output of the AND gate 17a is connected to the input of one of the OR gates 15a.

The output of the comparator 18a is connected to the other input of the R-15a. AND game) 17a is AND game) 16a
The AND gate 16a... takes the logical product of the L level output of the comparator 19a and the H level output of the comparator 19a, and the AND gate 16a...
It is assumed that the level output and the IH level output of the comparator 20a are ANDed.

A rotation sensor 21a is provided to detect the rotational speed of the wheel IR, and a pulse signal from the rotation sensor 21a is input to a wheel speed calculation circuit 22a. This circuit 22a calculates the wheel speed vWl of the wheel IR from the frequency of the pulse □ signal and the wheel rotation radius, and supplies the result to the wheel acceleration calculation circuit 28a1 subtractor 24a.

The circuit 28a calculates the wheel acceleration ζ from the wheel speed and inputs it to the comparators 18a and 19a.
・The comparator 18a indicates that the wheel deceleration vW is the deceleration reference value - b
The comparator 19a outputs an H level when the wheel acceleration ψ7 exceeds the acceleration reference value +a.The 0 subtractor 24a subtracts the allowable spin amount ΔvW from the wheel speed vWl, Input the result 1.V - ΔvW into the comparator goa ◇ Note that l The allowable spin amount Δvw is set to a value slightly larger than the wheel spin error that inevitably occurs while the wheels are being driven.

Drive wheel IR calculated by circuits 22a to 22d.

The wheel speeds vw□ to vw4 of IL, 2R, and 2L are supplied to the corresponding inputs of a common left-row switch 88, and this switch outputs the lowest value V of the wheel speeds v1□ to VW4.
The 0 pseudo vehicle speed generating circuit 40 selects 1 input of another select low switch 89 and supplies it to the pseudo vehicle speed generating circuit 40. The 0 pseudo vehicle speed generating circuit 40 generates a pseudo vehicle speed expected after wheelspin based on the minimum wheel speed value ■. Create v4 as described below,
The center) o-switch 89 selects the lower of the pseudo vehicle speed v1 and the minimum wheel speed vw, and selects the vehicle speed equivalent value viw.
is input to the comparator 2 oa-god as ◎ These comparators are input to the comparator 2θa.
Compare the calculated value VW□-ΔvW and the vehicle speed equivalent value viW, and find that VW,-ΔVw ≧Viy s Tsumari Vwx ≧”
When iw + ΔvW, the output is set to H level. The second @ shows a specific example of the pseudo vehicle speed generation circuit 40. 1 This circuit includes a sample hold circuit 26, a wheel acceleration calculation circuit 27, a comparator 2B, and a differentiation circuit 29' , monostable multipipe rake 80, and constant setting □ device 81
, an integrating circuit 82 , an adding circuit 88 , and an OR gate 84
．． 85 and inverters 86 and 87 are connected as shown in the figure. The 0 sample hold □ circuit 2B detects the minimum wheel speed value v selected by the select low switch 88.
W is input, the wheel speed VW(O) when the switching transistor 26a is turned on by the shot pulse is sampled and held, and this is input to the addition circuit 88. The wheel acceleration calculation circuit 27 calculates the wheel acceleration 9W from the wheel speed vW.
, and the comparator 28 compares this with the acceleration reference value a. ) Outputs an H level signal at 10a. In synchronization with the rising edge of this signal, the differentiating circuit 29 generates a shot bar signal, and the monostable multivibrator 80 outputs an H level signal for a set time. ON by
Otherwise, the constant value -m from the constant setter 81 is integrated, and the integrated value mf11'dt is input to the adding circuit 88.The zero adding circuit 88 outputs the wheel speed sampling value VW(O). In this configuration, the minimum wheel speed VW is as shown in Figure 8 (
Vehicle speed V. (also shown for reference), the pseudo vehicle speed V is determined as follows.

That is, in this case, the wheel acceleration ζ calculated by the circuit 27
is as shown in the same figure. During the instants t□ to tg and between t8 and t1 when the wheel acceleration 9W exceeds the reference value +a, the comparator 28 sets the output to the H level. In synchronization with the rise of the output, the monostable multivibrator 8o As shown in the figure, an H level signal is output for a set time ΔT,
From the instant t8 when the output of the comparator 28 rises during this set time Δτ, the monostable multivibrator 80 outputs an H level signal again for 31 hours, and at the instant t, 37 hours later, the monostable multivibrator 80 outputs an H level signal. The way sa comes out is L
Turn to level. Such a monostable multivibrator 80
The outputs of are inverted by inverters 86 and 87 as shown in FIG. 81 and input to OR gates 84 and 85.

At the moment t11t8 when the wheel acceleration ζ exceeds the reference value a and the output of the comparator 28 rises, the differentiating circuit 29 outputs a shot pulse as shown in FIG. 85. OR game! -) 134.8
Since 5 is supplied with the above-mentioned inverted output to another power, the switching transistors 26a and 132a are temporarily turned on, temporarily t□, t8 by the above-mentioned shot pulse.
Then, the wheel speed vw at this time is input to the sample hold circuit 26 as V.
It is extracted and held as W(O), and the integration circuit 82 is reset to restart integration. As shown in FIG. 8, VW(O) is instantaneous 1. , 18 wheel speed sampling values, and the integral value mf dt of the integrating circuit is the change in expected vehicle speed from the instant t Added value vW(o) 10m
Let fdt be the instant t, and the pseudo vehicle speed V expected after t8.
It can be defined as soil as shown in Figure 8. Note that the time gradient m can be arbitrarily set using the constant setting device 81. If the next output of the comparator 28 does not rise within 31 hours, the outputs of the inverters 86 and 87 will remain at the H level v(
0) = vW, mfdt = 0, the pseudo vehicle speed ■・ is the same as the minimum wheel speed ■...↓
Become W.

Here, each wheel IR, LL, 2R, 2L is the fourth
As shown in the upper part of the figure, when changing the wheel speed vWl~■74 (However, ■. is the vehicle speed shown for reference, and
w2=VW4) Specifically, the select low switch 38 in FIG.
Select as shown in the center of the figure, and select this minimum wheel speed value VW.
Based on this, the pseudo single series generation circuit 40 generates the pseudo vehicle speed vi as described above with reference to FIGS.
The select low switch 39 selects the lower of the pseudo vehicle speed V mode and the minimum wheel speed value VW, and selects the V mode as shown in the lower part of FIG. 4. is supplied to comparators 20a to 2od.

The effect of the above embodiment is as follows: All drive wheels IR, IL, ・2
For convenience of explanation, R and 2L rotated synchronously as shown by VW in Fig. 5 (VW ``' vWl '''' VW2 ''
VW3 "■.,)" case will be explained next.In this case, the wheel acceleration calculated by circuits 23a to 23ci in FIG. The wheel acceleration based on the minimum wheel speed calculated by the circuit 27 in FIG. 2 is also the same. As described above, the pseudo vehicle speed generation circuit 40 generates the instant 11.18.1 when the wheel acceleration* exceeds the reference speed a. , 47 per 1°
A pseudo vehicle speed vi is generated for the time, and the select low switch 89 supplies the lower of the pseudo vehicle speed and the wheel speed vw to the comparators 20a to 20d as a vehicle speed equivalent value vIW. As described above, each of the comparators 20a to 20god outputs an H level of 1.degree. as shown in FIG. 5 while the wheel speed VW exceeds viw+.DELTA.vW shown in FIG.

On the other hand, each of the comparators 18a to 18d outputs H as shown in FIG. 5 while the wheel deceleration ζ exceeds the deceleration reference value.
The level and comparators 19a to 19d are respectively wheel acceleration ■. comparator 18a N18d outputs an H level as shown in FIG.
, 19a N19d.

Depending on the output of 20a to 20d, OR Age-15a to 15
The outputs of AND gates 16a to 1ad(7) change in level as shown in FIG.

For the first time, the wheel acceleration ζ exceeds the reference value +a (up to the moment t□ in Fig. 5 is the OR gate 15a-15d and the AND game)
Since the output of 16a-16(i is at L level, transistors 18a-lad and 14a-14d are not conductive, and solenoid valves 10a-10d increase clutch pressure P. and Po4 by deenergizing all solenoids, respectively. Then, the wheel drive torque is increased as shown in Fig. 5 by increasing the engagement force of the corresponding clutch.0 As a result, when VW≧+a at instant t0,
OR Age-15a N15d output changes to H level)-
・Transistor 18a~ which is turned on by this output
When the solenoids 10a' to 10d' are energized via 1B+1, the solenoid valves 1oa-1od maintain the clutch pressure P.
. , ~P04 are held at their current values, and the wheel drive force is kept constant to prepare for wheel spin detection. 1 instant t, ~
During t8, when ζ<10a, there is clearly no wheel spin. During this time OR Age-15a-15d
The output returns to L level, and the clutch pressure P. , ~" Increase the vehicle width drive torque by increasing the pressure of 04. At instant t, VW≧10a,.

Then, as mentioned above, the clutch pressure P increases again. ,~lP
Hold O4 and prepare for wheel spin detection. Thereafter, when the wheel speed VW becomes equal to or higher than Vjw10Δ■o at instant t, it can be assumed that wheel spin has occurred, and at this time, the outputs of OR Age-15a to 1ad are set to L level and the AND game is ) 16a-1ad output to H
Thus, the transistors 18a-i8d are made non-conductive, deenergizing the solenoids lOa'-10d', and the transistors 14a-t4d are made conductive, energizing the solenoids 10a'-11.N10d". , the solenoid valves 10a to 10d reduce the clutch pressure P.
Due to this decrease in clutch pressure, the engagement force of the clutches 6a to 6d is weakened, and wheel drive torque can be reduced as shown in FIG. 5 to prevent wheel spin.Q This decreases wheel speed V, resulting in wheel deceleration (2). At the instant t, which is more than one, it can be assumed that the wheel spin has disappeared, and the outputs of the OR gates 15a to 15d change to H level, and the outputs of AND gates 16a to 16d change to L level. Clara.

Chi pressure P. , ~P04 are held at their current values and the wheel drive torque is
・Keep the torque constant and see how the wheels grip the road. At instant t6, when the wheel deceleration (VW becomes less than the reference value -b), the outputs of the OR gates 15a' to 15d change to the L level, and the wheel drive torque is increased by increasing the clutch pressure '1''OX to P04. 0
As a result of this rubbing, the moment t when the wheel acceleration ψ exceeds the standard driver a again
In , the outputs of OR Age-15a to 16d are changed to H level, so that 1...'clutch pressure'
OX~”04 is held at the current value, and during this period v
Unless w≧v1w+ΔvvI, the wheel acceleration t
At the instant t8 when becomes less than +a, the OR gate 15a
~15d output to L level and clutch pressure P. □〜P
At the moment t when the wheel acceleration ・■ becomes equal to or higher than the reference value +1 again, OR game) 15a-15
The output of d changes to H level, □Clutch pressure P
- OV, which holds P at its current value.

Wheel spin occurrence instant t1 when ≧vi, t+Δvw
From ゜, until the moment t0 when the wheel deceleration ψ becomes -5 or more, the outputs of OR game) 15a to 15d are set to L level and turned to 1 bell, and the outputs of AND game) 16a to 16d are changed to H level. , clutch pressure P. , ~Po, to reduce wheel drive torque and prevent wheel spin.

As a result of the above actions, the wheel drive torque is controlled so as to be kept as close as possible to the traction limit shown by TL in Fig. 5 when wheelspin occurs, and is kept at a maximum value in relation to this traction limit, thereby driving the vehicle. It is possible to run the vehicle without wheel spin or without unnecessarily restricting the wheel drive force.

(Effects of the Invention) Thus, as described above, the traction control device according to the first aspect of the present invention selects the lowest value among the wheel speeds for a vehicle with multiple driving wheels, and controls the wheel speed to be equal to or higher than a predetermined value with respect to the lowest wheel speed value. The driving wheel that has become ``driving wheel'' is regarded as wheel spin, and the torque transmitted to it is reduced to prevent wheel spin.Therefore, wheel speed information of the non-driving wheels is not required.
In addition, it becomes possible to perform traction control without the need for vehicle detection and means, which contributes to lower device costs and lower failure rates, as well as traction control even in all-drive vehicles that do not have non-drive wheels. enable.

Furthermore, as described above, the traction control device according to the second aspect of the present invention is configured such that the wheel speed is equal to or higher than a predetermined value with respect to the lower of the predicted pseudo vehicle speed during wheel spin created based on the minimum wheel speed value and the minimum wheel speed value. The driving wheels that have become . Even when there is no difference between wheel speeds, wheel spin can be detected using the above pseudo vehicle speed, and traction control can still be performed.

[Brief explanation of drawings]

Fig. 1 is a system diagram showing an embodiment of the traction control system according to the present invention; Fig. 2 is an electronic circuit diagram of a pseudo vehicle speed generation circuit on the same side; Fig. 8 is an explanatory diagram of operating waveforms of the same circuit; The figure is a diagram illustrating the vehicle speed equivalent value selected by the select low switch in the example shown in FIG. 1, and the second figure is an explanatory diagram of operation waveforms of the traction control device in FIG. 1. ...Wheels 1...Engine 5...Transmission 6a-6d...Hydraulic multi-disc clutches 7-9...D 7 Allencial gear 1oa-1Od...Spring center 2 8-position electromagnetic switching valve 11 . . . Constant pressure valve 12 . a -17d ・A N
D gates 18a to 18d, 19a to ioa,
S! Oa ~ 20d, - Comparator 21a ~ gxd
... Rotation sensors 22a to 22 (1... Wheel speed calculation circuits 28a to 28d
... Wheel acceleration calculation circuit la -24d - ... Subtractor 26 ... Sample hold circuit 27 ... Wheel acceleration calculation circuit 28 ... Comparator 29 ... Differentiation circuit 80 ... Monostable multivibrator 81 ...Constant setter 82...Integrator circuit 88...Addition circuit 84, 85...OR gate 86, 8? ...Reverser δ889...Select low switch 40...Pseudo vehicle speed generation circuit

Claims (1)

[Claims] 1. In a vehicle having a plurality of drive wheels, wheel speed detection means for detecting the wheel speed of each drive wheel, select low means for selecting the lowest value among these wheel speeds, and the lowest value. 1. A traction control device for a vehicle, comprising: torque reduction means for reducing torque transmitted to a drive wheel whose wheel speed exceeds a predetermined value in comparison with the above. 2. In a vehicle having a plurality of drive wheels, a wheel speed detection means for detecting the wheel speed of each drive wheel, a first select low means for selecting the lowest value among these wheel speeds, and based on the lowest value. a pseudo vehicle speed generating means for generating a pseudo vehicle speed expected during wheelspin; a second select low means for selecting the lower of the minimum value and the pseudo vehicle speed; and a value selected by the second select low means. A traction control device for a vehicle, characterized in that it is provided with a torque reduction means for reducing the torque transmitted to the driving wheels whose wheel speed exceeds a predetermined value in comparison.