JPH0330018B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a differential gear with a variable differential limiting device used in a vehicle.

BACKGROUND TECHNOLOGY To explain the conventional differential device 01 with a differential limiting device shown in FIG. 13, four pinion gears are rotatably supported by a cruciform pinion shaft 35 fixed to a differential case 32. 36 and side gears 37 and 38, which are spline-coupled to axle shafts 2 and 3 connected to left and right drive wheels, mesh with each other. Two pressure rings 39 and 40 are pinion shaft 3
5 and are splined to the case 32. Between each pressure ring 39, 40 and the case 32 are clutches 42, 4, each consisting of a plurality of friction disks 44, 47 and friction plates 45, 48 arranged alternately.
3 are interposed therebetween, and the disks 44 and 47 are spline-coupled to the side gears 37 and 38, and the plates 45 and 48 are spline-coupled to the case 32, respectively. When the road surface resistance of the left and right drive wheels is equal when the vehicle is traveling straight, the resistance applied to the left and right side gears 37 and 38 is equal, so the pinion gear 36 does not rotate, and the differential case 32 to which the ring gear 34 is fixed, and the front The gear rings 39 and 40, the pinion shaft 35, the pinion gear 36, and the side gears 37 and 38 rotate as a unit and transmit equal driving torque to the left and right wheels. On the other hand, when the vehicle turns, or when one wheel contacts a road surface with a high friction coefficient (paved road, etc.) and the opposite wheel contacts a road surface with a low friction coefficient (muddy ground, uneven ground, etc.), the ring gear 34
When the differential case 32 is rotated through the differential case 32, the pressure rings 39 and 40 rotate at the same speed. The side gear on the side (referred to as the locking wheel) rotates slower than the case 32, and the side gear on the side of the outer wheel or the opposite wheel (hereinafter referred to as the rotating wheel) during turning rotates faster than the case 32. For this reason, the V-shaped cam 50 formed at the end of the pinion shaft 35,
By cooperating with V-shaped grooves 51 and 52 formed in pressure rings 39 and 40, the rings are separated from each other and friction disks 44, 47 are moved.
and the friction plates 45 and 48 are pressed together to drive the locking wheel side gear, while the rotating wheel side gear is braked, and the friction torque resulting from this braking is transmitted to the locking wheel side gear via the case 32. The driving torque will increase.

Problems to be Solved by the Invention In such a conventional differential device, the differential limiting torque obtained by the friction torque is the same as that of the friction disks 44, 47 when the differential device is assembled.
It is preset to a predetermined value by the pressing force of clutches 42 and 43 made up of friction plates 45 and 48. This differential limiting torque is normally determined by: A braking phenomenon occurs due to the motion.

(2) If the differential limiting torque is set to a low value, it will be difficult to escape from muddy or uneven ground, and driving and braking stability of the vehicle on snowy roads etc. cannot be ensured.

It was set as a compromise between two contradictory factors. For this reason, it is practically impossible to always obtain optimal driving and braking stability for the vehicle depending on the road surface conditions. If you want to change the differential limiting torque depending on road conditions, you need to disassemble the differential, replace the clutch, and change the pushing force, which is not only very time-consuming, but also requires a lot of effort. This is not something a vehicle driver can easily do.

The purpose of the present invention is to make the differential limiting torque of the differential device variable in accordance with the driver's commands, driving conditions, or road surface conditions, thereby avoiding the above-mentioned braking phenomenon, escaping from muddy terrain, etc. It is an object of the present invention to provide a differential gear with a variable differential differential limiting device that facilitates running and improves driving and braking stability of a vehicle.

Means for Solving the Problems In order to achieve the above object, a differential device with a variable differential limiter for a vehicle according to the present invention is rotatably mounted on a pinion shaft fixed in a differential case. a pinion gear, a pair of left and right side gears meshing with the pinion gear and rotatably disposed within the differential case, and a pair of left and right side gears disposed between the differential case and the side gears to allow relative rotation of the side gears via the pinion gear. A differential device main body having a clutch that exerts a torque that limits the resulting differential operation, and a piston disposed within the differential case that applies a pressing force to the clutch in accordance with hydraulic pressure; a hydraulic pump that is installed in a differential carrier in which a differential case is housed and is rotationally driven by the differential case to suck in and discharge hydraulic oil stored in the differential carrier; The hydraulic control valve is selectively operated in accordance with the running condition of the vehicle to control the hydraulic pressure supplied from the hydraulic pump to the piston.

Effect According to the configuration of the present invention, the hydraulic pressure supplied to the pinion via the hydraulic control pulp can be controlled to a desired pressure value to change the differential limiting torque of the differential main body, so the differential By adjusting the limit torque to a desired torque value, it is possible to avoid braking phenomena, facilitate escape or travel from muddy terrain, and improve the driving and braking stability of the vehicle.

Embodiments Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

In the first embodiment of the differential gear with a variable differential limiting device according to the present invention shown in FIGS. 1 to 7,
The differential device includes a differential device main body 1 with a differential limiting device that transmits drive torque from an engine to axle shafts 2 and 3 connected to left and right drive wheels of a vehicle,
As will be described later, there is a hydraulic pump disposed inside the differential gear body 1 and an on/off control type hydraulic system that supplies the hydraulic oil pressure-fed from the pump 4 to the piston in the differential gear body 1 or returns it to the reservoir 5. control valve 6
If impurities clog the oil lines or hydraulic pipes 7 to 12 that connect the differential device body, the pump, the reservoir, and the valves, the hydraulic control valve 6, etc., the pressure in the pipe 8 increases, causing the pump 4 to overflow. It consists of a check valve 13 in the pipe line 12 that prevents loads from being applied.

The differential gear main body 1 with a differential limiting device has left and right ends in FIG.
The differential case 32 is rotatably supported within the vehicle via a bearing 31 (only the left side is shown in FIG. 1). The differential case 32 has two parts 32a.
and 32b, and are integrally fixed together with the ring gear 34 by a plurality of bolts 33. A cross-shaped pinion shaft 35 is fixedly disposed within the differential case 32, and four pinion gears 36 (only two are shown in FIG. 1) are rotatably mounted at the ends of the shaft. It is exteriorized. Side gears 37 and 38 splined to the axle shafts 2 and 3, respectively, mesh with the pinion gear 36.

The differential limiting device has two left and right pressure rings 39 and 40 that are arranged on both sides of the pinion shaft 35 and surround gears 36, 37, and 38, and the rings are connected to the differential case portion 32a.
The differential is movable in the axial direction of the axle shaft via a plurality of circumferentially spaced grooves or splines 41 (only one is shown in FIG. 1) in the inner wall of the differential. Sial case 3
2 is spline connected. Clutches 42 and 43 are interposed between the pressure rings 39 and 40 and the inner wall of the differential case 3. The clutch 42 consists of a plurality of annular friction disks 44 and friction plates 45 arranged alternately, and the friction disks 44 are provided on the outer surface of the shaft portion of the left side gear 37 at intervals in the circumferential direction. Via a plurality of grooves or splines 46, the friction plate 45 is spline-coupled to the gear 37 so as to be movable in the axial direction, while the friction plate 45 is spline-coupled to the differential case 32 so as to be movable in the axial direction via splines 41. has been done. Similarly, the clutch 43 consists of a plurality of alternating annular friction disks 47 and friction plates 48,
The friction disk 47 is the right side gear 3.
The friction plate 48 is spline-coupled to the gear 38 via a plurality of grooves or splines 49 provided at intervals in the circumferential direction on the outer surface of the shaft portion of the gear 8, and the friction plate 48 is connected to the differential case via the splines 41. 32 with a spline connection.

When a rotational speed difference occurs between the axle shafts 2 and 3 depending on the vehicle running condition, the clutch 4
A V-shaped cam 50 is formed at each end of the pinion shaft 35 to press the friction disks 44, 47 and the friction plates 45, 48 together.
V-shaped grooves 51 and 52 that fit with the cam 50 are formed on opposing surfaces of the cam 50.

Further, in order to be able to change the pressing force arbitrarily, an annular groove 53 is formed in the inner wall of the differential case portion 32b facing the left friction plate 45, and an annular piston 54 is formed in the groove 53. is mounted so as to be movable in the axial direction and engages with the friction plate 45, forming a pressure chamber 55 within the groove 53. The pressure chamber 55 is connected to the hydraulic control valve 6 via an oil passage 56 in the case portion 32b and an oil passage 63 in the differential carrier 30.

Furthermore, the hydraulic pump 4 is installed within the differential carrier 30. This hydraulic pump 4
is a gear pump consisting of an internal gear 91 and an external gear 92 that mesh with each other and are disposed in a pump 90 formed in the differential carrier 30. The external gear 92 is rotatably supported, and is assembled integrally or separately to the differential case portion 32b, and rotates together with the differential case portion 32b. The differential carrier 30 has the same carrier 30.
An oil passage 7 that communicates the reservoir 5 configured as an oil reservoir therein with the pump suction port 14 and an oil passage 95 that communicates the pump discharge port 15 with the inlet 70 of the hydraulic control valve 6 are provided. Therefore, when the differential case 32 rotates, the hydraulic oil in the reservoir 5 is sent to the suction port 14 via the oil path 7, and is sent through the discharge port 15 and the oil path 95 by the internal gear 91 and the external gear 92. The oil is then pressure-fed to the hydraulic control valve 6.
The hydraulic oil that has passed through the hydraulic control valve 6 is guided into the pressure chamber 55 through an oil passage 63 and directly through an oil passage 56 . Therefore, this hydraulic pump 4 uses differential gear oil for lubrication as the hydraulic oil.

Since the hydraulic pump 4 is of a variable flow rate type, in order to keep the flow rate of hydraulic oil to the hydraulic control valve 6 constant, a flow rate control is installed in the middle of the pipe line 8 connecting the hydraulic pump 4 and the hydraulic control valve 6. A valve 24 is provided. The flow control valve 24 includes a metering orifice 123 in an oil passage 122 between an inlet 120 connected to the hydraulic pump and an outlet 121 connected to the inlet 70 of the hydraulic control valve 6 . Oil passages 126 and 12 between the upstream and downstream sides of orifice 123 of oil passage 122 and two return ports 124 and 125 connected to reservoir 5
7, a flow rate regulating valve 128 and a metering orifice 129 are provided, respectively. The metering orifices 123 and 129 maintain a constant flow rate of the hydraulic oil guided to the outlet 121 and the hydraulic control valve 6, while the flow rate regulating valve 128 maintains the hydraulic pressure upstream of the orifice 123 in the oil passage 122 acting on its pressure receiving surface. When the force of the flow rate adjusting spring (not shown) becomes greater due to the action of the orifice 123, a portion of the hydraulic oil is transferred to the oil passage 126 and the return port 124.
It works to return the water to the reservoir 5 through the process. Since such a flow control valve is well known, a detailed explanation of its structure will be omitted.

The on/off control type hydraulic control valve 6 is connected to the conduit 8
Inlet 70 connected to pump 4 via line 9
a valve body 74 with an outlet 71 connected to the pressure chamber 55 of the differential body 1 via a valve body 74 and two return ports 72 and 73 connected to the reservoir 5 via lines 10 and 11; a spool 77 with two lands 75 and 76 slidably fitted therein to control communication between the inlet, outlet and return ports;
and solenoids 80 and 81 disposed about both enlarged shaft portions 78 and 79 of the same spool and corresponding ends of the valve body 74. Spool 77
is usually two opposing centering springs 8
2 and 83, it is held in the neutral or non-operating position A shown in FIGS. 2 and 3, communicating the inlet 70 and the return port 72, and the outlet 71 and the return port 73. When the solenoid 80 is energized, the spool 77 moves against the spring 82 to the point 1 in FIG.
It is sucked rightward toward the operating position B shown by the dotted chain line, communicating the inlet 70 and the outlet 71, while blocking the return ports 72 and 73. On the contrary, solenoid 81
When the spool 77 is energized, the spring 83
It is sucked to the left toward the oil pressure holding position C shown by the two-dot chain line against the pressure, thereby communicating the inlet 70 and the return port 72, while blocking the outlet 71 and the return port 73.

Solenoids 80 and 81 of the above hydraulic control valve 6
The supply and discharge of hydraulic oil to and from the differential main body 1 through excitation and demagnetization and hydraulic control are performed according to the driver's commands, which are arbitrarily set according to the operating conditions and road surface conditions, as shown in Fig. 4. Alternatively, as shown in FIG. 5, it can be performed automatically according to the road surface condition using information from the wheel speed sensors.

In the example shown in FIG. 4, a differential limiting torque adjustment switch 16 is disposed around the driver's seat in the vehicle interior. The driver sets switch 1 according to driving conditions and road surface conditions.
When the movable contact 17 of No. 6 is moved to the predetermined operating position,
Amplifier 20 built into controller 19
A constant voltage generated from the switch 16 is changed by a resistor 18 in the switch 16 and then inputted to the controller 19. The controller 19 issues a drive signal in response to this input voltage, moves the hydraulic control valve 6 to the operating position, holds this position for a predetermined time until a predetermined oil pressure is generated, and then moves the valve to the oil pressure holding position. As a result, from reservoir 5 to pump 4
The hydraulic oil pressure-fed through the hydraulic control valve 6
The differential gear body 1 is adjusted to a predetermined oil pressure by
It acts on the piston 54 inside, applying a predetermined pressing force to the clutch 42.

On the other hand, in the example of Fig. 5, axle shafts 2 and 3
Two wheel speed sensors 21 are mounted on the axle housing (not shown) to sense the rotational speed of each wheel, and these sensors may be of any conventional type. A speed signal from sensor 21 is input to controller 19. When the controller 19 detects from this input signal that the rotational speed difference between the axle shafts 2 and 3 is greater than or equal to a predetermined value, it issues a drive signal and operates the hydraulic control valve 6 as described above.

Next, the operation of the above-described differential gear with a limited slip differential device will be explained.

First, it is assumed that the hydraulic control valve 6 is in the non-operating position shown in FIGS. 2 and 3, the pressure chamber 55 of the differential gear body 1 is communicated with the reservoir 5, and no hydraulic pressure is generated.

When the road surface resistance of the left and right drive wheels is equal when the vehicle is traveling straight, when the ring gear 34 and the differential case 32 are rotated by the drive torque from the engine via the propulsion shaft and drive pinion (not shown), the case 32 The pressure rings 39 and 40, which are spline-coupled to each other, rotate at the same speed, and the V-shaped grooves 51 and 52 of the rings push the V-shaped cam 50 of the pinion shaft 35, so that the pressure rings 39 and 40 are rotated against each other. A clutch 4 comprising friction disks 44 and 47 and friction plates 45 and 48 spaced apart from each other.
Press 2 and 43 to engage them. Furthermore, since the resistance acting on the left and right side gears 37 and 38 is equal, the pinion gear 36 does not rotate. Therefore, differential loose 32, pressure rings 39 and 4
0, pinion shaft 35, pinion gear 36,
The side gears 37 and 38 and the axle shafts 2 and 3 rotate together, and an equal drive torque is transmitted to the drive wheels.

On the other hand, when the ring gear 34 and the differential case 32 are rotated when the vehicle turns, etc., the pressure rings 39 and 40 rotate at the same speed, but because they operate differentially due to the difference in road resistance. , the side gear 37 or 38 on the locking wheel side, which is the inner ring when turning, rotates slower than the case 32, and the side gear 37 or 38 on the rotating wheel side, which is the outer ring when turning, rotates slower than the case 32.
8 or 37 rotates faster than case 32. Therefore, by the action of the clutches 42 and 43 in the engaged state, the side gear on the rotating wheel side is braked, while the side gear on the locking wheel side is pulled in the driving direction, and the friction torque due to the braking of the clutch on the rotating wheel side is applied to the case. 32 and the lock wheel side clutch to the lock wheel side gear. As a result,
The driving torque of the rotating wheel is reduced by the amount of the friction torque, and conversely, the driving torque of the locking wheel is increased by the amount of the friction torque. Therefore, this friction torque constitutes a differential limiting torque that limits the differential operation of the differential gear main body 1, and as described above,
It is preset by the pressing force of 2 and 43.

Depending on driving conditions and road surface conditions, for example, when one wheel is in contact with a road surface with a high coefficient of friction such as a paved road, and the other wheel is in contact with a road surface with a low coefficient of friction such as a muddy, uneven, or snowy road, this may occur. If it is necessary to increase the differential limiting torque in order to prevent the opposite wheel from spinning, the controller 19 causes the adjustment switch 16 to be actuated to a predetermined position by the driver as described with respect to FIG. Alternatively, a drive signal is input to the hydraulic control valve 6 in response to a speed signal from the wheel speed sensor 21, as described in connection with FIG.

The solenoid 80 of the hydraulic control valve 6 is first energized and energized by the drive signal from the controller 19, and the spool 77 moves rightward from the non-operating position shown by the solid line in FIG. 3 to the operating position shown by the dashed-dotted line. be moved by As a result, the return ports 72 and 73 are blocked by the lands 75 and 76, while the inlet 70
and the outlet 71 are communicated with each other, and the hydraulic oil pumped from the hydraulic pump 4 is connected to the oil line 95, the pipe line 8, the flow control valve 24, the inlet 70, the outlet 71, the pipe line 9, and the oil line 63.
and 56 to the pressure chamber 55, and hydraulic pressure is generated in the same chamber. At this time, the controller 19
The energization time to the solenoid 80 is determined according to the operating position of the adjustment switch 16 or the rotational speed difference between the axle shafts 2 and 3 detected from the wheel speed sensor 21, and the hydraulic control valve 6 is activated as shown in FIG. The hydraulic pressure inside the pressure chamber 55 is controlled to a predetermined pressure value by changing the opening operation time t ₀ . The oil pressure in the pressure chamber 55 controlled in this way is controlled by the piston 54.
This hydraulic pressure forces the clutches 42 and 43 in the operating direction, and this hydraulic pressure increases the friction torque of the clutches and therefore increases the differential limiting torque.

When the oil pressure in the pressure chamber 55 reaches a predetermined pressure value, the controller 19 stops energizing the solenoid 80 of the hydraulic control valve 6 to demagnetize it, and at the same time energizes the solenoid 81 to excite it. As a result, the spool 77 moves from the operating position to 2 in FIG.
It is moved to the left to the hydraulic pressure holding position shown by the dotted chain line, and the inlet 70 and the return port 72 are communicated with each other, while the outlet 7
1 and the return port 73 are shut off, and the oil pressure in the pressure chamber 55 is maintained at the predetermined pressure value.

If it is necessary to reduce or cancel the increased differential limiting torque, the controller 19
stops energizing the solenoid 81 and demagnetizes it. As a result, the spool 77 is moved to the non-operating position by the action of both centering springs 82 and 83, and the hydraulic oil in the pressure chamber 55 flows through the oil lines 56 and 63, the line 9, the outlet 71, the return port 73 and the line Road 1
1 and 10, and is returned to the reservoir 5, and the pressure chamber 5
The oil pressure inside 5 decreases or becomes zero.

FIG. 7 shows the torque characteristics of a differential device with a variable differential limiting device that can obtain variable differential limiting torque in this manner. This differential limiting torque T ₀ is as follows: T ₀ = A・r・p・μ It can be expressed as a coefficient of friction, and therefore, the differential limiting torque T ₀ can be freely changed by changing the oil pressure p acting on the piston 54 at the driver's will or automatically.

Therefore, if the differential limiting torque T ₀ is set to a low torque value to prevent the occurrence of braking phenomena due to the rotation difference between the front and rear wheels or the left and right wheels when the vehicle turns at low speed, this torque T ₀ can be By increasing the number in this manner, it is possible to easily escape from or run on muddy or uneven ground. Furthermore, by appropriately adjusting this torque T ₀ , it is possible to obtain the optimum driving and braking stability of the vehicle according to the road surface conditions, and it is also possible to freely select the cornering characteristics of the vehicle according to the driving conditions.

A number of modifications of the first embodiment will be described.

In the first embodiment, the hydraulic pump 4 has a bearing 3
1 and the differential case 32, but it can also be installed outside the bearing 31, that is, on the left side of the bearing. or,
The oil passage 63 may communicate with the pressure chamber 55 via an oil reservoir in the axle shaft 2 and an oil passage in the differential case portion 32b.

In a modified example of the differential gear body with a differential limiting device, only the piston 54 that engages with the left clutch 42 is provided in the first embodiment, but a piston that engages with the right clutch 43 may be additionally provided. Of course it is possible.

In another modification of the differential gear body with a differential limiting device, in the first embodiment, there is a groove between the groove 53 of the differential case portion 32b and the piston 54.
If there is a gap, there is a risk that when hydraulic pressure is generated in the pressure chamber 55, hydraulic oil may leak into the differential case 32 through this gap, resulting in a decrease in the hydraulic pressure and thus the differential limiting torque. However, in order to prevent this oil pressure drop, there are two holes between the groove 53 and the piston 54.
Two inner and outer annular seals may be provided.

In yet another modification of the differential device body with a differential limiting device, in the first embodiment, the friction plate 45 of the clutch 42 in contact with the piston 54
is in the form of a disc spring, and even when no hydraulic pressure is generated in the pressure chamber 55, the clutches 42 and 43 are
A certain amount of pressing force is applied to the friction plate 45 in advance, and an initial value of the differential limiting torque is set. However, if it is not necessary to set this initial value in advance, the friction plate 45 may be replaced with a flat ring. It may be of any shape.

A first modification of the hydraulic circuit shown in FIG. 8 is one in which the four-port hydraulic control valve 6 in the above embodiment is replaced with a three-port hydraulic control valve 6'.
This hydraulic control valve 6' has an inlet connected to the pump 4 via a pipe line 8 and a flow rate control valve 24, an outlet connected to a pressure chamber 55 of the differential gear body 1 via a pipe line 9, and a pipe line. It has a return port connected to the reservoir 5 via 10. As in the first embodiment, the valve 6' is normally held in the inactive position A to provide communication between the inlet, outlet and return port, and is moved to the activated position B when one of the solenoids is energized. The inlet and outlet are communicated and the return port is blocked, and when the other solenoid is energized, it is moved to the oil pressure holding position C to block the outlet and communicate the inlet and return port. In this hydraulic circuit, the first
The pipe line 11 in the embodiment can be omitted, and the piping can be simplified.

In a second modification of the hydraulic circuit shown in FIG. 9, the hydraulic control valve 6 in the first embodiment is replaced with two hydraulic control valves 6''a and 6''b. The hydraulic control valve 6″a is a four-port type, and has an inlet connected to the pump 4 via a pipe line 8 and a flow rate control valve 24, and communicates with the pressure chamber 55 of the differential gear body 1 via a pipe line 9. The hydraulic control valve 6″b is of the open/close type;
It is arranged in the middle of the conduit 9. In the inoperative position, the valve 6''a is in a position A' communicating between the inlet and one return port and the outlet and the other return port, and the valve 6''b is in an open position C'. Pressure chamber 55
In the operating position, the solenoid of valve 6″a is energized, and the valve
The valve 6''b moves to position B', which communicates between the inlet and the outlet and blocks both return ports, and the valve 6''b remains in the open position C'. The solenoid of valve 6″a is de-energized and returns to position A′, and the solenoid of valve 6″b is energized and the valve is in the closed position.
Move to D′.

The hydraulic control valve 6 used in the hydraulic circuit of the first embodiment is an on-off control type;
A second embodiment of the differential gear with a variable differential limiting device according to the present invention shown in FIGS. The hydraulic pressure inside the pressure chamber 55 of the differential gear body 1 with a differential limiting device is duty-controlled.

The hydraulic control valve 22 has an inlet 1 connected to the hydraulic pump 4 via a conduit 8 and a flow control valve 24.
00, the pressure chamber 5 of the differential device main body 1 via the pipe line 9
A valve body 103 includes an outlet 101 connected to the reservoir 5 and a return port 102 connected to the reservoir 5 via a conduit 10; Spool 1 with two lands 104 and 105 for controlling communication
06 and a solenoid 107 disposed around one end of the spool. The spool 106 is normally connected to the inlet 1 by a return spring 108.
00, is held in the inoperative position shown to allow free flow of hydraulic fluid between outlet 101 and return port 102. Displacement of spool 106 from the inoperative position is controlled by duty control of solenoid 107 by controller 19. This controller 19 responds to the input voltage corresponding to the operating position of the differential limiting torque adjustment switch 16, as explained in connection with FIG. 4, or the speed signal from the wheel speed sensor 21, as explained in connection with FIG. A drive pulse signal is input to the solenoid 107. In addition, the controller 19 has
The amount of displacement x of the spool 106 detected by the displacement sensor 23 provided at the opposite end of the spool 106 is fed back.

To explain the operation of this hydraulic control valve 22, the solenoid 107 is not energized and the spool 1
06 is in the non-operating position shown, hydraulic oil led from the pump 4 to the inlet 100 passes through two orifices 109 and 110 formed between both edges of the outlet 101 and both sides of the land 104. Since the oil can freely flow to the return port 102, no hydraulic pressure is generated in the pressure chamber 55 of the differential device main body 1.

If it is necessary to increase the differential limiting torque,
The solenoid 107 is energized and excited by a drive pulse signal from the controller 19, and the spool 106 is moved to the left in the figure. As a result, orifice 109 is opened and at the same time orifice 1 is opened.
10 is squeezed, hydraulic pressure is generated in the outlet 101,
This oil pressure communicates with the pressure chamber 55 of the differential main body 1 and applies a pressing force to the clutches 42 and 43. At this time, the controller 19 determines the energization time ₁ to the solenoid 107 per unit time t according to the operating position of the adjustment switch 16 or the rotational speed difference between the axle shafts 2 and 3 detected from the wheel speed sensor 21. Then, as shown in FIG. 11, the spool 106 is displaced as a function of the effective value of the voltage applied to the solenoid, and the valve opening y at the orifice 109 is adjusted. Spool 1
The actual displacement amount x of 06 is detected by the displacement sensor 23 and fed back to the controller 19, and the controller compares this actual displacement amount with a preset displacement amount, and if necessary, matches the two displacement amounts. Thus, the energization time to the solenoid 107 is corrected.

A modification of the second embodiment shown in FIG. 12 is such that the hydraulic control shown in FIG. This is a modification of the valve 22. This duty control type hydraulic pressure control valve 22' is not subjected to feedback control based on the amount of displacement of the spool 106, but is subjected to feedback control based on the oil pressure in the pipe line 9 connecting the outlet 101 and the differential gear main body 1. It is becoming more and more common. For this reason, a pressure sensor 25 is disposed in the middle of the conduit 9, and a pressure signal detected by the sensor is fed back to the controller 19. During generation of the drive pulse signal, the controller 19 controls the solenoid 10 while comparing the actual pressure value in the conduit 9 with a preset desired pressure value.
The power supply time t ₁ to 7 is corrected.
The rest of the structure and operation is the same as described with respect to FIG.

Although a number of embodiments of the invention have been illustrated and described, the invention is not limited thereto, and can be practiced with numerous changes and modifications without departing from the scope of the invention.

Effects of the Invention As described above, the differential gear with a variable differential limiting device according to the present invention has a piston that engages the clutch in the differential gear body, and adjusts the speed of movement according to operating conditions or road surface conditions via a hydraulic control valve. The differential limiting torque of the differential gear body can be changed by the driver's command or by applying automatically controlled hydraulic pressure to the piston. (1) By lowering the differential limiting torque. Therefore, it is possible to avoid the braking phenomenon of the vehicle that occurs due to the difference in rotation between the front and rear wheels or the left and right wheels when the vehicle turns at low speed on a paved road.

(2) By increasing the differential limiting torque, it is possible to make it easier to escape from or drive on muddy or uneven ground.

(3) By appropriately adjusting the differential limiting torque, it is possible to obtain optimal driving and braking stability for the vehicle depending on the road surface conditions, and it is also possible to freely adjust the cornering characteristics of the vehicle when turning to suit the driving conditions. can be selected.

It is possible to achieve the following effects.

Furthermore, according to the present invention, the hydraulic pump is incorporated into the differential gear body and sucks in and discharges oil stored in the differential carrier, making the device more compact and easier to assemble. It is possible to achieve excellent practical effects such as sharing oil for differential limiting control and lubrication.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a differential device main body showing a first embodiment of a differential device with a variable differential limiting device according to the present invention, FIG. 2 is a schematic hydraulic circuit diagram in the first embodiment, and FIG. 2 is a detailed sectional view of the hydraulic control valve shown in FIG. 2, FIG. 4 is a block diagram showing an example of a control circuit for a hydraulic control valve, and FIG. 5 is a block diagram showing another example of a control circuit for a hydraulic control valve. Figure 6 is a voltage characteristic diagram for the hydraulic control valve by the control circuit, Figure 7
The figure is the differential limiting torque characteristic diagram of the differential gear main body, No. 8
The figure shows a first modification of the hydraulic circuit, FIG. 9 shows a second modification of the hydraulic circuit, and FIG. 10 shows a second embodiment of a differential with a variable differential limiting device. A schematic sectional view of the control valve, FIG. 11 is a voltage characteristic diagram to the hydraulic control valve in the second embodiment, and FIG.
The figure is a schematic sectional view of a hydraulic control valve showing a modification of the second embodiment of the differential, and FIG. 13 is a sectional view of a conventional differential with a differential limiting device. DESCRIPTION OF SYMBOLS 1... Differential gear body with differential limiting device, 4... Hydraulic pump, 5... Reservoir, 6, 22... Hydraulic control valve, 16... Differential limiting torque adjustment switch, 19...
Controller, 21... Wheel speed sensor, 23... Displacement sensor, 24... Flow rate control valve, 25... Pressure sensor, 30... Differential carrier, 32
...differential case, 34...ring gear, 35...pinion shaft, 36...pinion gear, 37, 38...side gear, 39,40...pressure ring, 42,43...clutch, 44,4
7... Friction disk, 45, 48... Friction plate, 50... Cam, 51, 52... Groove,
54... Piston, 55... Pressure chamber, 77... Spool, 80, 81, 107... Solenoid, 90... Pump chamber, 91... Internal gear, 92... External gear.

Claims (1)

[Claims] 1. A pinion gear rotatably mounted on a pinion shaft fixed in the differential case, a pair of left and right side gears meshing with the pinion gear and rotatably disposed in the differential case, a clutch disposed between the differential case and the side gear, which exerts a torque to limit differential operation caused by relative rotation of the side gear via the pinion gear; and a clutch disposed within the differential case, which responds to hydraulic pressure. a differential gear body having a piston that applies a pressing force to the clutch; and a differential carrier in which the differential case is housed; A hydraulic pump that sucks in and discharges hydraulic oil stored in the allencial carrier, and a hydraulic control valve that is selectively operated according to the running condition of the vehicle and controls the hydraulic pressure supplied from the hydraulic pump to the piston. A differential gear with a variable differential limiting device for a vehicle, comprising: