JPH04292227A - Differential controller - Google Patents

Abstract

PURPOSE:To control the extent of differential limit by means of a factor other than a steering angle at a time when a signal out of a steering angle detecting means has gone wrong. CONSTITUTION:A controller or a central processing unit finds 119 added hydraulic pressure P from an car speed and a steering angle, and controls an operating means in order to give this added hydraulic pressure P to a differential limiting mechanism, and when the signal out of the steering angle detecting means is out of order, it operates a speed difference DELTAomega between front and rear wheels, and the added hydraulic pressure P is found 128 out of a map through this speed difference, thus the operating means is controlled in order to impart the added hydraulic pressure P to the differential limiting mechanism.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a differential control device, and more particularly, to a vehicle in which left and right wheels are driven by a differential device having a differential limiting mechanism that can continuously change the differential limiting amount. The present invention relates to a device for controlling the differential of the differential device.

0002

[Prior Art] A controller installed in a differential control device is
In addition to calculating the rotation speed difference between the left and right drive wheels, a reference rotation speed difference is determined from the vehicle speed and steering angle, and the reference rotation speed difference is compared with the calculated rotation speed difference, and the calculated rotation speed difference is determined as the reference rotation speed. When the difference is greater than the difference in rotation speed, a differential limiting signal that changes according to the difference between the calculated rotation speed difference and the reference rotation speed difference is output, and after that, when the calculated rotation speed difference becomes less than or equal to the reference rotation speed difference. A differential control device has been proposed that calculates a correction value that changes depending on the accelerator opening or the engine speed, and outputs a differential limit signal obtained by subtracting this correction value from the value of the differential limit signal. (Utility Application No. 1-109640).

0003

[Problems to be Solved by the Invention] In a differential control device that obtains a reference value from vehicle speed and steering angle, it is necessary to adjust the steering angle so that the change in differential restriction amount due to changes in steering angle becomes large. It may be set. In this case, if an abnormality occurs in the means for detecting the rudder angle itself or in the wiring from this means to the controller, and a situation occurs in which a normal rudder angle signal does not reach the controller, the control will become abnormal or the control will be interrupted. It will have to be canceled.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a differential control device that can control the differential limiting amount based on factors other than the steering angle when the signal from the steering angle detection means becomes abnormal.

[0005]

[Means for Solving the Problems] The present invention provides a differential system for a vehicle in which left and right wheels are driven by a differential system having a differential limiting mechanism that can continuously change the differential limiting amount. It is a device that controls the The differential control device is
Means for detecting vehicle speed, means for detecting steering angle, means for detecting the number of revolutions of the left front wheel, means for detecting the number of revolutions of the right front wheel, and means for detecting the number of revolutions of the left rear wheel. and means for detecting the rotational speed of the right rear wheel, a controller receiving signals from these means, and means controlled by the controller to operate the differential limiting mechanism. When the signal from the steering angle detection means is normal, the controller controls the operating means to apply additional hydraulic pressure determined from the vehicle speed and the steering angle to the differential limiting mechanism, When the signal is abnormal, the operating means is controlled to provide the differential limiting mechanism with additional oil pressure determined from the rotational speed difference between the front and rear wheels.

[0006]

[Operations and Effects] When the signal from the steering angle detecting means is normal, the controller controls the operating means to apply the additional hydraulic pressure determined from the vehicle speed and the steering angle to the differential limiting mechanism. If a disconnection, short circuit, damage, or other accident occurs in the steering angle detection means itself or in the wiring from the steering angle detection means to the controller, and the signal is determined to be abnormal, the controller will The additional hydraulic pressure is determined and the operating means is controlled to apply the additional hydraulic pressure to the differential limiting mechanism.

[0007] Even if the signal from the steering angle detection means is abnormal, the additional oil pressure is determined from the difference in rotational speed between the front and rear wheels and the differential limiting mechanism is controlled, thereby avoiding situations such as control suspension. Can be done.

When the signal from the steering angle detection means is abnormal, the turning radius is estimated from the rotational speed difference between the two non-driven left and right wheels, and the turning radius is controlled to match the rotational speed difference between the driving wheels. Can be done. This makes it possible to ensure acceleration.

[0009]

[Embodiment] As shown in FIG. 1, a differential control device controls the differential of a differential device in a vehicle in which left and right wheels (not shown) are driven by a differential device having a differential limiting mechanism 10. 12, a means 14 for detecting the steering angle, a means 16 for detecting the rotation speed of the left front wheel, a means 17 for detecting the rotation speed of the right front wheel, and a means 17 for detecting the rotation speed of the right front wheel. Means 18 for detecting the rotation speed of the rear wheel, means 19 for detecting the rotation speed of the right rear wheel, and means 20 for detecting the presence or absence of braking.
and a controller 22 receiving signals from these means.
and an operating means 24.

[0010] As the differential device, a known one having a differential limiting mechanism that can continuously change the differential limiting amount can be used. In the differential device 26 shown in FIG. 2, a plurality of pinions 3 disposed within the differential case 28
A pair of side gears 32 that mesh with 0 (both 1 and 3 in the figure)
A differential limiting mechanism 10 is provided in association with one of the shafts 34 connected to the differential case 28 and one of the shafts 34 connected to the differential case 28, respectively.

The differential limiting mechanism 10 has one shaft 34
a plurality of first friction plates 3 that engage with each other via spacers 36;
8, and a plurality of second friction plates 42 that engage with the differential case 28 via a transmission member 40. 1st
A friction plate 38 is supported by the spacer 36 so as to be non-rotatable but movable in the axial direction of the shaft 34 . A second friction plate 42 is supported by the enlarged diameter portion of the transmission member 40 so as to be non-rotatable and movable in the axial direction. 1st
The friction plates 38 and the second friction plates 42 are arranged alternately.

A piston chamber 46 is provided in the differential carrier 44, and a piston 48 is disposed within the piston chamber 46 so as to be non-rotatable and movable in the axial direction. A piston 50 is non-rotatably but movably supported by the spacer 36 and is spaced apart from the piston 48 . A thrust bearing 52 is located between piston 48 and piston 50.

When hydraulic pressure is introduced into the piston chamber 46 from the outside through the pipe 54, the piston 48 moves into the thrust bearing 5.
2, and a friction force proportional to the pressing force is generated between the first friction plate 38 and the second friction plate 42. This frictional force continuously limits the differential movement of the differential device 26.

The means 12 for detecting the vehicle speed, the means 14 for detecting the steering angle, the means 16 to 19 for detecting the number of rotations, and the means 20 for detecting the presence or absence of braking are per se known detectors.

The controller 22 is a CPU or a computer, and as described later, the steering angle detecting means 14
When the signal from the steering angle detecting means 14 is normal, the operating means 24 is controlled to apply additional hydraulic pressure determined from the vehicle speed and steering angle to the differential limiting mechanism 10, and when the signal from the steering angle detecting means 14 is abnormal, the front and rear wheels The operating means 24 is controlled to apply the additional oil pressure determined from the rotational speed difference to the differential limiting mechanism 10.

In the embodiment shown in FIG. 1, the operating means 24 includes:
Liquid pump 60, unload relief valve 62, accumulator 64, current control pressure reducing valve 66, check valve 6
8.

A tube 54 is connected to the pump 60 and the differential limiting mechanism 10. An unload relief valve 62 is installed in the pipe 54, and a current-controlled pressure reducing valve 66 is installed in a portion leading from the unload relief valve 62 to the differential limiting mechanism 10. Further, the accumulator 64 is connected to the unload relief valve 6.
2 and the current-controlled pressure reducing valve 66, the check valve 6
8 is an unload relief valve 62 and an accumulator 64
It is incorporated between. Check valve 68 only allows liquid flow or pressure transfer from unload relief valve 62 to accumulator 64 .

When pressure fluid is supplied from the pump 60, the unload seat of the unload relief valve 62 is closed.
Check valve 68 opens. As a result, pressurized fluid from pump 60 is directed through pipe 54 to accumulator 64, where the fluid pressure increases. When the pressure in the accumulator 64 reaches the adjustment pressure of the unload relief valve 62, the unload relief valve 62 instantly opens, the pressurized liquid from the pump 60 flows back to the reservoir tank 70, and the check valve 68 closes. In this way, a constant pressure is stored in the accumulator 64.

The current-controlled pressure reducing valve 66 is equipped with a DC solenoid in its pilot section, and by controlling the input current to this solenoid, pressure is controlled continuously and steplessly. The control pressure in this case is then substantially proportional to the input current. Therefore, if the current applied to the current-controlled pressure reducing valve 66 is controlled by the controller 22, an appropriate pressure can be obtained.

The controller 22 performs calculations and judgments as shown in FIG. 3, and controls the operating means 24.

After initialization, read the steering angle δ (100
), read the vehicle speed u (101), and calculate the rotation speed ω1 of each wheel,
ω2, ω3, and ω4 are read (102). after that,
The rudder angle δ is compared with the reference value δ1 (103), and when the rudder angle δ is less than the reference value δ1, the rudder angle δ is set to the reference value δ.
2 (104).

The steering angle detection means generally converts the magnitude of the angle into the magnitude of the voltage value and outputs the voltage value. Its value is
For example, 2.5v is set as neutral, that is, the steering angle is zero, 0.25v is set as the limit for turning to the left, and 4.75v is set as the limit for turning to the right. Therefore, for example, the value of δ1 is 5v and the value of δ2 is 0.1.
By setting v, it is possible to determine whether the state is normal or abnormal.

When the steering angle δ is greater than the reference angle δ1, it is determined whether the flag is ON (105). If the flag is not ON, turn the flag ON (106);
Set T=0 (107). When the flag is ON, T
=T+1 (108), and then the magnitude of T and the reference value TK is determined (109). This is because an abnormality is recognized only after the routine has been executed a predetermined number of times. T
is greater than TK, turn on the abnormality flag (1
10).

When the steering angle δ is less than the upper limit reference value δ1, the magnitude of the steering angle δ and the lower limit reference value δ2 is compared (
104). Then, when the steering angle δ is equal to or greater than the reference value δ2, the flag is turned OFF and the abnormality flag is turned OFF (111). This is a state in which a signal indicating a normal steering angle is output.

When the steering angle δ is smaller than the reference value δ2, it is determined whether the flag is ON or not (112). If the flag is not ON, turn the flag ON (113) and set T=
Set to 0 (114). When the flag is ON, T=T
+1 (115), and then the magnitude of T and the reference value TK is determined (116). When T is greater than TK,
The abnormality flag is turned ON (117).

[0026] Determine whether the abnormality flag is ON or not (
118), if there is no abnormality, the additional oil pressure P is determined from the steering angle δ and the vehicle speed u (119). The additional oil pressure P is stored in advance as a map 80, as shown in FIG. This map 80 shows that in the low speed range, the differential is limited up to a medium steering angle, in the medium speed range, the differential is released at a relatively small steering angle, and in the high speed range above a certain vehicle speed, the differential is limited. The differential restriction is set to be strongly applied up to the steering angle. and,
Even if the vehicle speed is constant, when the steering angle increases, the effect of differential limiting is gradually reduced. In other words, as the steering angle decreases, the effect of differential limiting is gradually increased. It has been set.

By using the map set as described above, it is possible to impose a relatively strong differential restriction up to a certain steering angle in the low speed range, which improves the ease of getting out of the mud and the different friction coefficients of the left and right drive wheels. It is possible to ensure starting acceleration when the vehicle is on a road surface of 300 degrees, and to prevent the occurrence of tight corner braking by canceling the differential restriction when the steering angle is large. By releasing the differential restriction relatively early in the medium speed range, it is possible to improve the ease with which the front portion of the vehicle turns, that is, the turning performance when entering a turn from straight ahead. By increasing the differential restriction over a wide steering angle range at high speeds, it is possible to prevent changes in lane change performance, steering response, and vehicle steering characteristics due to changes in the strength of the differential restriction.

After determining the additional hydraulic pressure P to be applied to the differential limiting mechanism, the current i corresponding to this additional hydraulic pressure P is determined from the map 82 shown in FIG. 5 (120). After that, the brake signal is read (121), and it is determined whether or not braking is being performed (122). When braking is not being performed, the current i is output to the current-controlled pressure reducing valve 66 (123). Then, the hydraulic pressure P is supplied to the piston chamber 46, and a frictional force proportional to the hydraulic pressure is generated by contact between the friction plates 38 and 42, and the differential movement of the differential device 26 is restricted. When braking, i=0 (124) and output this current (12
3). This avoids limiting the differential during braking.

When the abnormality flag is ON, the rotational speed difference Δωf of the front wheels and the rotational speed difference Δωr of the rear wheels are calculated (1
25), further, the difference Δω between the rotational speed difference Δωr of the rear wheels and the rotational speed difference Δωf of the front wheels is determined (126). Then, the magnitude of the difference Δω and the reference value ωK is determined (127). In the example, it is assumed that the rear wheels are the driving wheels, but the difference Δ
It is determined whether the rear wheels are slipping based on the magnitude of ω. Therefore, the reference value ωK is set to a value larger than the rotational speed difference due to the difference in turning radius between the front wheels and the rear wheels during turning.

[0030] When the difference Δω is larger than the reference value ωK,
The additional oil pressure P corresponding to Δω is determined from the map 84 shown in FIG. 6 (128), and the control current i is determined from the additional oil pressure P (128).
120). In addition, the rotational speed difference Δω between the front and rear wheels is the reference value ωK
If it is below, P=0 (129). this is,
When there is no difference in rotational speed between the front and rear wheels, there is no slippage, so the idea is to cancel the differential restriction and ensure turning performance.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a differential control device.

FIG. 2 is a cross-sectional view of the differential.

FIG. 3 is a control flowchart.

FIG. 4 is a map stored in the controller.

FIG. 5 is a map stored in the controller.

FIG. 6 is a map stored in the controller.

[Explanation of symbols]

10 Differential limiting mechanism 12 Vehicle speed detection means 14 Rudder angle detection means 16, 17, 18, 19 Rotation speed detection means 20 Brake detection means 22 Controller 24 Operation means 26 Differential device 66 Current control pressure reducing valve

Claims (1)

[Claims] 1. A device for controlling the differential of a differential device in a vehicle in which left and right wheels are driven by a differential device having a differential limiting mechanism that can continuously change the differential limiting amount, comprising: Means for detecting vehicle speed, means for detecting steering angle, means for detecting the number of revolutions of the left front wheel, means for detecting the number of revolutions of the right front wheel, and means for detecting the number of revolutions of the left rear wheel. means for detecting the rotational speed of the right rear wheel; a controller receiving signals from these means; and means controlled by the controller to operate the differential limiting mechanism; When the signal from the detection means is normal, controlling the operating means to apply additional hydraulic pressure determined from the vehicle speed and steering angle to the differential limiting mechanism, and when the signal from the steering angle detection means is abnormal, A differential control device that controls the operating means to apply additional hydraulic pressure determined from a rotational speed difference between front and rear wheels to the differential limiting mechanism.