JPH03217332A - Control device for limited slip differential - Google Patents

Abstract

PURPOSE:To improve starting ability on a slope by exerting a given working pressure on a cylinder during braking even when a car speed is approximately zero, in a device which performs a differential limit by bringing friction discs located between the one side gear and a differential case into a connection state by means of a cylinder. CONSTITUTION:A limited slip differential engages a drive pinion 10 at the tip part of a propeller shaft with a ring gear 14 secured to a differential case 16. Side gears 17 and 18 and four differential pinions 21 and 22 rotatably mounted on a cross-shaped spider 23 are disposed in the differential case 16. An air cylinder 27 is mounted on the one side of the differential case 16, and by operating a piston 28 therein, friction discs 29... and 30... spline-coupled with the casing 27 and the side gear 17, respectively, are pressed to perform a differential limit. In this case, control is made such that even when a car speed is approximately zero, a given working pressure is exerted on the air cylinder 27 and especially starting ability on a slope is improved.

Description

[Detailed description of the invention]

K Field of Industrial Application] The present invention relates to a limited slip differential control device,
In particular, it relates to a IIIll device in a limited slip differential in which a friction plate is provided between one side gear and a differential case, and the differential is limited by connecting the friction plate with an actuator such as an oil cylinder or an air cylinder. .

[Summary of the invention]

In a limited slip differential, the differential is limited by applying operating pressure to an actuator such as an air cylinder and frictionally coupling a friction plate.
Moreover, the differential of the limited slip differential is limited during braking, and for example, when starting on a slope, the differential of the limited slip differential can be limited immediately after starting. This is what I did. K. Prior Art When an automobile turns, the outer wheels travel a longer distance than the inner wheels. In order to absorb the difference in rotational speed between the left and right wheels, especially the drive wheels, when turning, a differential gear device, or differential, is installed between the left and right drive shafts. Due to the difference in resistance applied to the left and right drive wheels when turning, the rotation of the propeller shaft is transmitted to the left and right wheels at different rates by the differential device, allowing the car to turn without straining each part. . However, if such a differential is provided, the wheels will slip when one of the wheels falls into mud or when driving on a road surface with a low coefficient of friction such as a snowy road. In other words, the differential impairs the ability to start and run on a road surface with a low coefficient of friction. In order to eliminate these drawbacks, a differential lock device or a limited slip differential is installed on the differential. [Problems to be solved by the K invention] A limited slip differential is provided with a plurality of friction plates between the side gear of the differential gear and the differential case, and these friction plates are frictionally connected by an air cylinder or the like. The differential is limited by the following. The above air cylinder is tIIJI! by computer.
In addition, computers are
The rotational speeds of the left and right front wheels and the left and right rear wheels are respectively detected and input by rotation detection sensors. A predetermined operating pressure is applied to the air cylinder depending on the state of the vehicle. Further, when slip of the drive wheels is detected, the limited slip differential is locked, thereby preventing slip. A brake signal is supplied to the computer of such an electronically controlled limited slip differential, and when the brake pedal is depressed, the limited slip differential is released. Therefore, in the case of a hill start where the start operation is performed immediately after the brake pedal is released, no operating pressure is applied to the limited slip differential cylinder immediately after the start, and the limited slip differential is activated after a time lag period has elapsed. The cylinder operating pressure will rise. Therefore, when starting on a slope on a road surface with a low coefficient of friction, the limited slip differential cannot be expected to prevent slipping as described above, so the wheels will slip, which may reduce the starting performance. Ta. The present invention has been made in view of these problems, and is a limited vehicle that prevents the wheels from slipping when starting on a slope on a road surface with a low coefficient of friction, thereby improving starting performance. Slip differential tjlJIll
The purpose is to provide a device. [Means for Solving the κ Problem] The present invention provides a friction plate between one side gear and a differential case, and performs a differential limit by connecting the friction plate with a cylinder constituting an actuator. In the limited slip differential, a predetermined operating pressure is applied to the cylinder when the vehicle speed is approximately O and braking is in progress. K effect 1 Therefore, when the vehicle speed is near O and braking is in progress, a predetermined operating pressure is applied to the cylinder.
When starting on a slope, the starting operation is performed with operating pressure applied to the limited slip differential. Therefore, the limited slip differential comes into play from the moment you start, and even if you start on a slope on a road surface with a low coefficient of friction, the drive wheels will be prevented from slipping, thereby improving the performance of starting on a slope. . K Embodiment FIG. 1 shows a limited slip differential according to an embodiment of the present invention, and this limited slip differential includes a drive pinion 10. As shown in FIG. The drive binion 10 is connected to the tip of the blower shaft, and is rotatably supported by the housing 11 by front and rear bearings 12 and 13. The drive pinion 10 is adapted to mesh with the ring gear 14. The ring gear 14 is fixed to the differential case 16 with bolts 15. Inside the differential case 16 are a pair of left and right side gears 17 and 18.
are arranged. These side gears 17 and 18 are fixed to drive shafts 19 and 20, respectively, and are connected to drive shaft 1.
Torque is transmitted to the drive wheels via the wheels 9 and 20. In addition, there are four differential binions 2 inside the differential case 16.
1 and 22 are arranged. These differential binions 21,
22 is connected to the differential case 1 via a cross-shaped divider 23.
6 is supported. The differential case 16 is fixed to the carrier case by bearings 24 on both sides, and is supported rotatably about the axes of the drive shafts 19 and 20. A casing 27 constituting an air cylinder is attached to the right side of the differential case 16 in FIG. A piston 28 is disposed within the air cylinder 27 and is configured to press friction plates 29 and 30 that are stacked on top of each other. Friction plate 29 among friction plates 29 and 30 in casing 27
The outer peripheral part is the spline 31 of the casing 27.
At the same time, the center portion of the friction plate 30 is engaged with the spline 32 of the side gear 17. An air pipe 36 is connected to the casing 27 constituting the air cylinder of the limited slip differential via a joint 35. An air tank 37 is connected to this air piping 36, and a solenoid valve 38 is connected in the middle of the air piping 36. Further, a branch pipe 39 for exhaust is connected to the air pipe 36, and a solenoid valve 40 is connected to this branch pipe 39. The pair of electromagnetic valves 38 and 40 are controlled by a controller 43 consisting of a computer. Further, a pressure gauge 44 connected to the branch pipe 39 is connected to the controller 43. Further, rotation detection sensors 45 to 48 are connected to the controller 43 to detect the respective rotational speeds of the left and right front wheels and the left and right rear wheels of the vehicle. Furthermore, a brake switch 49 that detects whether or not the brake is activated, and a manual switch 50 that manually switches the operation of the limited slip differential are connected to the controller 43. In the above configuration, if the air cylinder 27 having the friction plates 29 and 30 is removed from the limited slip differential shown in FIG. 1, it functions as a normal differential. That is, the torque transmitted via the brake shaft is transmitted to the ring gear 14 by the drive unit 10, and the differential case 16 to which the ring gear 14 is fixed rotates. Since the four differential binions 21 and 22 are attached to the differential case 16 via the divider 23, when the resistance of the left and right drive wheels is the same, the differential binions 21 and 22
2 hooks the left and right side gears 17 and 18 and rotates. Therefore, in this case, torque is transmitted to the left and right drive wheels through the drive shafts 19 and 20 at the same rotation speed. The rotational speed of the drive wheels at this time is equal to the rotational speed of the ring gear 14. On the other hand, when the resistance of one of the drive wheels increases, the side gear 17 connected to this drive wheel becomes difficult to rotate, so the differential gears 21 and 22 rotate together with the differential case 16 while shifting on the side gear 17. Therefore, in this case, the rotation accompanying the revolution of the differential case 16 and the rotation accompanying the rotation of the differential binions 21 and 22 are caused by the rotation of the side gear 1.
8 to the drive shaft 20, and the rotational speed of the drive wheel with less resistance increases. In this way, when the vehicle turns, the difference in rotational speed is absorbed depending on the travel distance of the left and right drive wheels. When the solenoid valve 38 is switched by the controller 43, the air stored in the air tank 37 is supplied to the air cylinder 27 through the air pipe 36, and the piston 28 is pushed to the left in FIG. The piston 28 then frictionally connects the friction plates 29 and 30 to each other. The friction plate 29 is attached to the spline 31 on the case 27 side.
o are respectively engaged with the splines 32 on the outer peripheral surface of the boss of the side gear 17, so when the friction plates 29, 3o are frictionally coupled to each other, the side gear 17 is connected to the friction plates 29, 3o.
30 and the casing 27 to be mechanically coupled to the differential case 16. Then, the relative movement between the side gears 17 and the differential binions 21 and 22 supported by the differential case 16 via the slider 23 is not allowed, resulting in a limited differential state. As a result, the original function of the differential is limited, and it only has the function of transmitting approximately equal rotational speed to the left and right drive wheels. FIG. 2 shows the control operation of the limited slip differential by the computer 43.
The rotation speed of the left and right front wheels and the left and right rear wheels is measured by the rotation sensor 45~
48, and the vehicle speed is calculated from the number of rotations of the driven wheels. Also, a brake signal is read from the output of the brake switch 49. When there is no brake signal, that is, when the brake pedal is not depressed, the brake pedal 43 performs a normal differential limiting operation of a limited slip differential. This differential limiting operation is performed by adjusting the air cylinder 27 of the limited slip differential to an appropriate operating pressure according to the vehicle speed while referring to a map stored in the memory of the computer 43.
A pair of solenoid valves 38 and 40 are controlled to maintain the internal pressure. If pressure is insufficient, solenoid valve 3
8 to supply compressed air into the air cylinder 27. When the operating pressure is excessive, the solenoid valve 40 is opened and the compressed air in the air cylinder 27 is discharged. Therefore, the frictional coupling force between the friction plates 29 and 30 of the limited slip differential has a value that corresponds to the vehicle speed, and the torque that limits the differential is maintained at an appropriate value. If a brake signal is present, that is, if the brake pedal is being depressed, the presence or absence of vehicle speed is determined. If the brake signal is ON and the vehicle speed is present, the differential of the limited slip differential is released. This is because the differential limiting operation of the limited slip differential inhibits the operation of the anti-skid brake.
By freeing the limited slip differential, reliable operation of the anti-skid brake is achieved. Further, when the brake signal is ON and the vehicle is not speeding, that is, when the vehicle is stopped and the brake pedal is depressed, a predetermined operating pressure is applied to the limited slip differential. Previously, when the brake pedal was pressed, the limited slip differential was unconditionally released, so when starting on a slope, where the starting operation is performed immediately after the brake pedal is released, the limited slip differential is automatically released after the brake pedal is released. There was a time lag before the system started working, and there was a possibility that the wheels could slip during this time. However, when the brake signal is ON and the vehicle speed is O, applying operating pressure to the limited slip differential as described above improves the ability to start on a slope on a road surface with a low coefficient of friction. That is, due to the above operation, even if the brake is depressed when the vehicle is stopped, a medium operating pressure is applied to the air cylinder 27, and the limited slip differential is in a state where the differential is limited. Therefore, even when starting by switching from the brake pedal to the accelerator pedal, such as when starting on a slope, it is possible to immediately utilize the limited slip differential from the time of starting. Therefore, hill start performance is improved on road surfaces with a low friction coefficient or on road surfaces with different friction coefficients between the left and right wheels. Effects of the Invention 1 As described above, in the present invention, a predetermined operating pressure is applied to the cylinder when the vehicle speed is approximately 0 and the brake is being applied. Therefore, even when starting on a slope where the starting operation is performed by changing the foot from the brake pedal, the limited slip differential can be applied immediately from the start, improving hill starting performance on road surfaces with a low coefficient of friction. Become.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a limited slip differential control device according to an embodiment of the present invention, and FIG. 2 is a flow chart of the control operation. The names of the main parts in the drawings are as follows. 16...Differential case 17...Side gear 27...Casing (air cylinder) 29, 30
...Friction plates 38, 40...Solenoid valve 43...Controller (computer) 45...
... Wheel rotation sensor (front left) 46 ... Wheel rotation sensor (front right) 47 ... Wheel rotation sensor (left rear)
48... Wheel rotation sensor (right rear) 49...
Brake switch diagram 2

Claims (1)

[Claims] 1. In a limited slip differential, a friction plate is provided between one side gear and the differential case, and the differential is limited by connecting the friction plate with a cylinder that constitutes an actuator. A limited slip differential control device, characterized in that a predetermined operating pressure is applied to the cylinder when braking is in progress.