JPS6192927A - Differential control device of vehicle - Google Patents

Abstract

PURPOSE:To prevent right and left drive wheels from being simultaneously locked by providing control means for periodically increasing and decreasing a differential limit action in response to conditions of damping a vehicle, in a differential limit mechanism for producing differential resistance whereby limiting a differential operation of a differential mechanism. CONSTITUTION:A differential mechanism 1 is arranged such that engine power is distributed to left and right drive shafts 3, and includes a drive pinion 6 provided at the end of an input shaft 2, a driven gear 8 engaged with said drive gear and disposed on the outer periphery of a differential case 7, a couple of pinion gears 11 with its shaft rotatably supported 10 in the differential case 7, and a side gear 12 engaged with said pinion gears 11 and disposed on the left and right drive shafts 3. Thereupon, a differential limit mechanism 4 is provided for limiting differential rotation of the left and right drive shafts 3, and arranged to drive two left and right sets of clutch mechanisms 15 by operating a piston 26 via a push rod 25. Delivery/discharge of pressure oil to/ from the piston 26 is controlled by a solenoid valve 31 in response to an output from a brake sensor, whereby a differential limit action is periodically increased and decreased.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a differential control device for a vehicle, and more specifically, a differential control device for a vehicle that rotates an outer wheel faster than an inner wheel during a turn. When this occurs, the system controls the differential action of the differential device, which has a differential limiting action, to limit the differential action and transmit even stronger torque to the other axle to facilitate escape, depending on the vehicle braking situation. The present invention relates to a differential control device for a vehicle.

(Prior Art) A differential device having such a differential limiting action has conventionally been disclosed in Nirasan Service Bulletin No. 446 (October 1982).
(Limited slip differential) as described on page 69 and after (published by Nissan Motor Co., Ltd.). In this conventional differential device, as described in the same magazine, the pressure ring is pushed away from each other by the cam action with the pinion mate shaft, and this pressing force generates a clutch action, preventing the fixed side from idling. With a fixed torque ratio, it is possible to transmit a torque several times the torque transmitted to a wheel that is idling. Even if the torque transmitted to the wheel on the idling side is extremely small, the preload created by the action of the disk spring makes it possible to transmit the initial torque to the other grounded wheel on the fixed side and run.

On the other hand, if the rear wheels are simultaneously locked before the front wheels when braking the vehicle, the road friction force in the left and right direction of the rear wheels will be almost eliminated.
Even the slightest imbalance can cause what is called a tail swing, which can be extremely dangerous. Steering operation is possible, but
If the tail wagging phenomenon occurs more rapidly than expected, it will be difficult to correct it. At this time, if only one of the rear wheels is not locked, hip swing can be prevented to a minimum.

However, in the conventional differential system as described above, a preload is always exerted between the left and right driven wheels due to the action of the disc spring, and even when the torque transmitted to the wheel is extremely small when the wheels are idling, Although the structure is capable of transmitting initial torque to the ground-contact wheels, during braking when no driving torque is applied, it was not possible to bring the left and right wheels close to a directly connected state. Therefore, if the road friction coefficients of the left and right wheels are slightly different, and one wheel is locked first, the locked state is released by rotating the locked wheel with the other wheel using the initial torque. I couldn't. In addition, if the initial torque is set high to prevent the one-wheel lock described above, the limit of single-wheel lock will increase, but if both wheels eventually lock, it will be difficult to release the lock, and the above-mentioned tail wobbling phenomenon will occur. There has been a problem in that there is a risk that the running stability of the vehicle may deteriorate due to the above.

(Object of the Invention) Therefore, the present invention prevents the left and right drive wheels from being locked at the same time and deteriorating the running stability of the vehicle by providing a control means that controls the differential limiting action according to the vehicle braking situation. The purpose is to

(Structure of the Invention) A differential control device for a vehicle according to the present invention is a differential control device that distributes and transmits driving force input from an input section to left and right drive wheels via two output sections that can be differentially applied to each other. a differential limiting mechanism that generates a differential resistance force to limit the differential operation of the differential mechanism; and a differential limiting mechanism that is connected to the differential limiting mechanism and periodically limits the differential depending on the vehicle braking situation. A control means for controlling increase/decrease;
It is configured to have the following.

(Example) Hereinafter, an example of the present invention will be described based on the drawings. 1 to 6 are diagrams showing a differential control device for a vehicle according to an embodiment of the present invention.

First, to explain the configuration, in FIG. 1, an output shaft of an engine is connected to an input shaft (input section) 2 of a differential mechanism 1 via a transmission and a propeller shaft. This differential mechanism 1 transmits the power of the engine to two left and right drive shafts (output parts) 3 in order to distribute it to the left and right drive wheels, and also has a differential limiter that limits the differential rotation of the left and right drive wheels. It is equipped with a mechanism 4.

More specifically, the differential mechanism 1 includes a driven gear 8 fixed to the outer periphery of the differential case 7 so as to mesh with a drive pinion 6 fitted to the end of the input shaft 2. 2, the differential case 7 rotates. A pinion mate shaft 10 is disposed inside the differential case 7 in a direction perpendicular to the axis on which the differential case 7 rotates, and a pair of pinion mate gears 11 (one shown in the figure) is attached to both ends of the pinion mate shaft 10. omitted)
is rotatably supported. Also, inside the differential case 7, a pair of side gears 12 mesh with both pinion mate gears 11 and coaxially face each other, and can rotate integrally with the left and right drive shafts 3 rotatably supported by the housing 22. is connected to.

The differential limiting mechanism 4 also includes a pinion mate gear 11.
A pressure ring 13 covering the side gear 12 is disposed within the differential case 7. This pressure ring 13 is divided into left and right halves, with a square groove (not shown) provided at each opposing end, and a binion mate shaft that fits into this groove and has a substantially square cross section. It supports both ends of 10. Further, a protrusion formed in the axial direction on the outer periphery of the pressure ring 13 is slidably fitted into a groove formed in the inside of the differential case 7, so that the pressure ring 3 and the differential case 7 are connected to each other in the axial direction (Fig. It can slide in the left and right direction. Furthermore, between the differential case 7 and the pressure ring 13 in the differential case 7, there are two sets of clutch mechanisms 15 on the left and right in the figure, which are made up of multiple plates and connect the differential case 7 and the shaft portions 12a of the left and right side gears 12. It is provided.

Each clutch mechanism 15 is provided between the pressure ring 13 and the differential case 7 in the left and right direction (drive shaft 3
It is composed of friction disks 16 and friction plates 17 which are arranged so as to overlap alternately in the axial direction). The friction disk 16 has a protrusion on its inner circumference that is slidably fitted into a groove on the outer circumference of the shaft portion 12a of the side gear 12, and rotates integrally with the side gear 12. On the other hand, the friction plate 17 has a protrusion on its outer periphery that is slidably fitted into a groove on the inner periphery of the differential case 7, and rotates integrally with the differential case 7. Furthermore, reaction plates 18 made of annular disks are disposed outside both ends of the differential case 7, and a plurality of protrusions 18a are formed on the side of the differential case 7 of each reaction plate 18, and each of these protrusions 18a loosely passes through a plurality of corresponding holes provided in the differential case 7 and comes into contact with the friction plate 17. An annular spacer 21 is attached to the side of each reaction plate 18 opposite to the differential case 7 via a bearing 20, and the rear crayon plate 1 is rotatably supported coaxially with the differential case 7 by the bearing 20. ing. Further, each spacer 21 is connected to the differential case 7.
The bearing 2 is fitted into a housing 22 that houses the bearing 2.
0, clutch mechanism 1 via reaction plate 18
5 can be slid in the direction of pressing. Furthermore, an insertion hole 23 is formed at the left end of the housing 22 in the figure, and opens opposite to the spacer 21 and extends parallel to the drive shaft 3. A bushing rod 25 is inserted into the insertion hole 23, and one end of the bushing rod 25 is connected to the spacer. 21 so as to come into contact with it. An annular piston 26 is disposed in contact with the other end of the bushing rod 25, and this piston 26 is connected to the housing 2.
2 is slidably housed in an annular cylinder hole 27 formed in the cylinder hole 27 .

An oil passage 28 is connected to the left side of the cylinder hole 27 in the figure, and when pressure oil is supplied from this oil 17828, the piston 2
6 presses the bushing rod 25 to the right in the figure and opens the oil passage 28.
By removing the pressure oil from the bushing rod 25, the pressing force on the bushing rod 25 is reduced. An oil-tight seal member 30 is interposed between the piston 26 and the housing 22 forming the cylinder hole 27. As shown in FIG. 2, the oil passage 28 is connected to the reservoir tank 3 via a solenoid valve 31.
2 and a hydraulic pump 35 via a check valve 33. The opposite side of the check valve 33 from the hydraulic pump 35 communicates with the reservoir tank 32 via a relief valve 36 , and the hydraulic pump 35 is driven by a motor 37 . The oil pressure supplied to the cylinder hole 27 through the oil passage 28 is detected by the pressure switch 38, and when the oil pressure is less than the set value, the pressure switch 38 sends a signal to the control circuit 40, and the control circuit 40 operates based on this signal. A signal is sent to the motor 37 to drive the hydraulic pump 35. When the oil pressure rises significantly above the set value, it is lowered by the relief valve 36. The control circuit 40 receives a signal output from a brake sensor (vehicle braking detection means) 41 and controls the duty of the solenoid valve 31 based on this signal. The brake sensor 41 detects the braking state of the vehicle by measuring the braking pressure or braking deceleration of the vehicle. As shown in FIG. 3, the control circuit 40 receives a signal from the brake sensor 41 and operates as shown in FIG.
A set voltage generator 42 outputs a set voltage signal E as shown in FIG. 1, a triangular wave generator 43 generates a triangular wave signal as shown in FIG.
The comparator 45 outputs a pulse signal P as shown in FIG. As shown in FIG.
is a brake maintenance sensor unit 46 that detects the brake maintenance state of the vehicle.
, a square wave generator 47 that generates a square wave signal, and
The square wave generator 4 is activated by the signal from the braking maintenance sensor section 46.
It has a relay 49 that outputs the rectangular wave signal from 7 to the outside. Further, the set voltage generator 42 is connected to a reference voltage generator 48 that generates a reference voltage, and a reference voltage generator 4 that receives a rectangular wave input signal in both positive and negative directions as shown in FIG. 6 from the brake sensor 41. The sixth voltage is determined by the generated reference voltage.
The adder 50 corrects the rectangular wave to a positive-direction only rectangular wave and outputs it to the comparator 45 as shown in FIG. The comparator 45 inputs such a rectangular wave signal from the set voltage generator 42, and when ON, it receives the set voltage signal E corresponding to the upper limit value at this time and the triangular wave signal from the triangular wave generator 43 as described above. Based on this, a pulse signal P as shown in FIG. 4(b) is output to the solenoid valve 31, and such a pulse signal P is not output to the solenoid valve 31 when it is OFF. The period of the rectangular wave generated by the rectangular wave generator 47 is about 1 to 2 seconds, and the period of the triangular wave generated by the triangular wave generator 43 is set to about 1/100 seconds.

By the way, while driving, a predetermined pressure is always introduced into the cylinder hole 27 from the oil passage 28, and for this reason, the piston 26
, bushing rod 25, spacer 21, bearing 20
Preload is always applied to the clutch mechanism 15 via the reaction plate 18.

Next, the effect will be explained. When the left and right drive wheels of the vehicle are both in contact with the ground and the vehicle is turning, the differential mechanism 1 rotates the outer wheels faster than the inner wheels to enable smooth turning. When one of the drive wheels gets stuck in mud or the like and its drive torque becomes small, the differential limiting mechanism 4 as described above applies a constant torque ratio to the other ground drive wheel so that it does not drive at all in mud or the like. It is possible to transmit a torque several times larger than the drive torque of the wheels, making it easier to escape from muddy areas and the like.

The road surface is partly puddled or frozen, and the coefficient of friction between each wheel and the road surface is not constant.
Particularly when the respective road surface friction coefficients of the left and right rear driving wheels of the vehicle are slightly different, when the vehicle starts a braking operation, the brake maintenance sensor section 46 of the brake sensor 41 outputs a signal to the relay 49. As a result, the relay 49 is turned on, outputting the rectangular wave signal from the rectangular wave generator 47 to the adder 50 of the set voltage generator 42, and further outputting the rectangular wave signal from the rectangular wave generator 47 to the adder 50
0 adds the rectangular wave signal to the level of the reference signal from the reference voltage generator 48 and outputs the result to the comparator 45. When this rectangular wave signal is ON (Fig. 6 (E value in C1)), the comparator 45 outputs the set voltage E from the set voltage generator 42 and the triangular wave generator 43 as shown in Fig. 4 (al). Fig. 4('b) is calculated based on this comparison.
A pulse signal P as shown in is generated and output to the solenoid valve 31 to control the solenoid valve 31 in duty. When the solenoid valve 31 is duty-controlled by inputting the pulse signal P, the oil pressure supplied from the oil passage 28 to the cylinder hole 27 increases, and the oil pressure is increased through the piston 26, bushing rod 25, spacer 21, bearing 20, and reaction plate 18. A pressure greater than the preload is applied to the clutch mechanism 15. The square wave signal is OFF (
O value in TCI in FIG. 6), the comparator 45 does not compare the signals as in FIG.
A pulse signal P as shown in bl is not generated, and furthermore, a signal is not output to the solenoid valve 31. Therefore, the oil pressure supplied from the oil passage 28 to the cylinder hole 27 becomes low again, and the pressure applied to the clutch mechanism 15 returns to the original preload. In this way, the oil pressure fluctuates by increasing or decreasing due to the 0N-OFF change of the square wave signal from the set voltage generator 42, and as a result, the pressure applied to the clutch mechanism 15 also increases or returns to the preload. and fluctuates at 1.2 second intervals (depending on the period of the square wave).

When a pressure greater than the preload is applied to the clutch mechanism 15, even if one wheel attempts to lock first during vehicle braking due to a low coefficient of road friction, the other wheel that is not yet locked will attempt to lock one wheel. A torque is transmitted to the wheels that is capable of rotating one of the wheels.

Therefore, the limit value at which one wheel tends to lock can be improved. However, if a pressure greater than the preload remains applied to the clutch mechanism 15 during vehicle braking, if both the left and right wheels are locked, even if at least one wheel attempts to rotate due to the reverse driving force from the road surface, it will be difficult to rotate, and both wheels will be locked. Continue. Therefore, in order to satisfy these conflicting demands, the present invention varies the pressure applied to the clutch mechanism 15 as described above.

(Effects of the Invention) As described above, according to the present invention, it is possible to prevent the left and right drive wheels from being locked at the same time and the running stability of the vehicle from being deteriorated.

[Brief explanation of the drawing]

1 to 6 are diagrams showing a differential control device for a vehicle according to an embodiment of the present invention, FIG. 1 is a cross-sectional side view of a differential mechanism having a differential limiting mechanism, and FIG. FIG. 3 is a correlation diagram between the hydraulic circuit that supplies hydraulic pressure from the oil passage 28 into the cylinder hole 27 and the block diagram of the control means that controls the differential limiting action according to the vehicle braking situation. A block diagram showing details of the control circuit 40 in the figure, FIG. 4(a) is a set voltage signal E outputted by the control voltage generator 42 in FIG.
FIG. 4 (b) is a waveform diagram showing a state in which the comparator 45 compares the triangular wave signal output from the triangular wave generator 43 and the triangular wave signal output from the triangular wave generator 43.
) is a waveform diagram of the pulse signal P outputted by the comparator 45 based on the comparison of the waveform diagrams in FIG. 4(a), and FIG.
Brake sensor 41 and set voltage generator 4 in the figure
Block diagram showing details of 2, 6th TI! J(a) is a diagram showing the state in which the brake maintenance sensor unit 46 outputs a signal when the vehicle is braked, FIG. 4 is a waveform diagram of a signal output from a set voltage generator 42 to a comparator 45 during braking. FIG. 1------1 differential mechanism, 2-----input shaft (input section), 3---1 drive shaft (output section), 4-- differential limiting mechanism, 31・-・Solenoid valve, 40・-----control circuit, 41----brake sensor (vehicle braking detection means)
.

Claims (2)

[Claims] (1) A differential mechanism that distributes and transmits the driving force input from the input section to the left and right drive wheels via two output sections that can be differentially applied to each other, and a differential mechanism that generates a differential resistance force to drive the differential The present invention is characterized by comprising a differential limiting mechanism that limits the differential operation of the mechanism, and a control means that is connected to the differential limiting mechanism and that periodically increases or decreases the differential limiting effect in accordance with vehicle braking conditions. differential control device for vehicles. (2) The control means includes a vehicle braking detection means for detecting the presence or absence of braking of the vehicle, a control circuit that outputs a signal based on a signal from the vehicle braking detection means, and a control circuit coupled to the differential limiting mechanism. a solenoid valve that controls the differential limiting action of the differential limiting mechanism based on a signal from a control circuit;
A differential control device for a vehicle according to claim 1, comprising: