JPH0534266Y2 - - Google Patents

Description

[Detailed description of the invention] <Industrial field of application> This invention is an automobile that improves the ability to escape from rough roads or uneven terrain by limiting the function of the differential mechanism built into the automobile's drive system. Regarding the limited slip differential (meaning a differential equipped with a mechanism that limits the operation of a differential mechanism; the same applies hereinafter), in detail, it is a device that allows the degree of restriction to be variably controlled based on an external signal. It is related to.

<Prior Art> When one drive wheel of an automobile gets stuck in a low-friction road surface such as a muddy or snowy road, the ground resistance (transmitted torque) of this drive wheel becomes small. In this case, only a similar small torque can be transmitted to the opposite drive wheel due to the differential operation by the differential mechanism, and the drive torque of the entire vehicle decreases, making it difficult to escape.

In order to solve this problem, various limited slip differentials have been proposed in which a clutch mechanism is provided inside the differential mechanism and the reduction in drive torque is prevented by operating this clutch mechanism. It has been put into practical use.

In other words, in the past, torque proportional By incorporating a type operation limiter, preload type differential limiter, torque proportional preload type differential limiter, mechanical differential limiter, or ZF type differential lock mechanism into the differential mechanism, it is possible to prevent single-wheel slippage. In addition to preventing the steering wheel from being taken off, it also improved the ability to escape from low-friction roads.

<Problems to be solved by the invention> However, in conventional limited slip differentials, the differential mechanism is not restricted until the rotational difference between the left and right drive wheels becomes sufficiently high. Since the left and right axle shafts were configured to be fixed when the function was restricted, there was a problem in that the torque applied to each axle shaft suddenly changed, reducing running stability.
Furthermore, when an on/off type differential limiting device that is manually operated is provided, as seen in Japanese Patent Publication No. 43-30338, the degree of limiting the differential function changes rapidly. Put it away. Therefore, if the technical concept of such an on-off type differential limiting device is applied as is to a variable limited slip differential of an automobile, a problem arises in that the driving stability of the automobile is impaired.

The present invention was devised to solve these conventional problems, and when it becomes necessary to limit the differential function or when it is convenient to limit the operating function, it is possible to The purpose is to gradually activate the differential limiting function to prevent sudden changes in torque and improve vehicle driving stability without reducing escape performance on low-friction roads. There is.

<Means for solving the problem> In order to achieve the above purpose, in this invention,
A spring is provided that urges the side gear, which is movably mounted in the axial direction, to slide toward the center of the differential case. Further, the clutch plate that is engaged with the side gear in a non-rotating manner and the friction plate that is engaged with the differential case in a non-rotating manner are arranged between a positioning surface formed on the outer surface of the side gear and a support surface provided on the inner surface of the differential case. They are alternately polymerized to form a friction clutch mechanism. The side gear is coupled to a piston inserted into a cylinder formed on the outer surface of the differential case, and a control means is provided for controlling the internal pressure of the cylinder to increase or decrease in accordance with the rotation difference between the left and right drive wheels. The present invention is characterized in that the side gear is moved outward against a spring as the internal pressure increases, thereby increasing the transmission torque of the friction clutch mechanism.

[Effect]

In the automatic variable limited slip differential configured as described above, the control means lowers the internal pressure of the cylinder under normal running conditions in which the rotational difference between the left and right drive wheels is smaller than a predetermined value. Then, because the side gear moves toward the center of the differential case under the biasing force of the spring, the distance between the positioning surface formed on the side gear and the support surface provided on the differential case increases. In this way, as the distance between the positioning surface and the support surface increases, the frictional force between the clutch plate and the friction plate (the transmission torque of the friction clutch) becomes smaller, and the frictional force between the side gear and the differential case becomes smaller. Therefore, the operation restriction function deteriorates, and the turning performance (maneuvering performance) of the car decreases.
is ensured.

Note that when the internal pressure of the cylinder is maintained at the same value as atmospheric pressure, for example, the biasing force of the spring moves and holds the side gear largely toward the center, preventing the friction clutch mechanism from dragging and creating a smooth differential. In addition to ensuring operational efficiency, this movement reduces backlash of the side gears to substantially zero, thereby reducing differential noise.

Further, for example, if one of the drive wheels gets stuck in a low-friction road surface and the rotation difference between the left and right drive wheels becomes larger than a predetermined value, the control means increases the internal pressure of the cylinder. Then, the side gear is pulled outward against the biasing force of the spring, reducing the distance between the positioning surface and the supporting surface. This increases the frictional force between the clutch plate and the friction plate, causing the friction clutch to tighten. Transmitted torque increases. In this way, when the transmission torque of the friction clutch increases, the friction force between the side gear and the differential case increases, and the operation limiting function increases, so the escape performance on low-friction roads is improved, or on straight roads. Improves straight-line performance (driving stability).

<Example> Embodiments of the present invention will be described in detail below.

FIG. 1 is a schematic cross-sectional view of the essential parts of an embodiment of the variable limited slip differential for an automobile according to the present invention, in which a pair of left and right side gears 2 are pivotally attached to a differential case 1 housed in a differential carrier (not shown). At the same time, the spider 3 fixed to the differential case 1
By pivotally mounting a pinion 4 to the shaft, both side gears 2 are interlocked via the pinion 4. Note that this configuration is similar to that of a conventional differential mechanism. 5 is a ring gear fixed to the differential case 1, and 6 is an axle shaft spline-fitted to the side gear 2, through which the side gear 2 and a driving wheel (not shown) are interlocked.

Of the pair of left and right side gears 2, the side gear 2 located on the right side in the figure is pivotally attached so as to be slidable in the axial direction of the gear 2 (left-right direction in the figure).
Also, the side gear 2 is slidably supported in the axial direction.
The positioning surface 7 formed on the outer end surface of the differential case 1
A clutch plate 9 is placed between the support surface 8 formed on the inner surface of the
and the friction plates 10 are alternately superposed. The clutch plate 9 is engaged with the side gear 2 in a non-rotating manner, and the friction plate 10 is engaged with the differential case 1 in a non-rotating manner to form a friction clutch mechanism.

On the other hand, a cylinder 11 is formed at the end of the differential case 1 along the axial direction of the side gear 2, and a piston 12 is slidably fitted into the cylinder 11.
is tightened and fixed to the tip of the boss portion of the side gear 2 with a bolt (not shown), so that as the piston 12 moves within the cylinder 11, the side gear 2 moves in the left-right direction in the figure, and the clutch plate 9 and the friction plate 10 are moved. It is designed to increase or decrease the frictional force between the

Furthermore, by interposing an electromagnetic three-way valve 15 in the pipe line 14 connecting the inside of the cylinder 11 and the working fluid supply source (air tank in the embodiment) 13,
Based on the output of the controller 16, the electromagnetic three-way valve 1
The internal pressure of the cylinder 11 can be increased or decreased by opening and closing the cylinder 5. Reference numeral 17 denotes a spring that slides and biases the side gear 2 to the right in the figure in order to reduce the pressing force between the clutch plate 9 and the friction plate 10. Signals related to vehicle number, vehicle speed, etc. are each supplied as control information.

In the variable limited differential of an automobile configured in this way, when the rotation difference between the left and right drive wheels (rear wheels) is smaller than a predetermined value, that is, when the automobile is being driven normally, the signal from the controller 16 is Therefore, the electromagnetic three-way valve 15 opens the inside of the cylinder 11 to the atmosphere.

Therefore, in this state, the internal pressure of the cylinder 11 is maintained at the same level as the atmospheric pressure, so the spring 17
The side gear 2 is pushed to the left side in the figure by the urging force of , and the contact pressure between the clutch plate 9 and the friction plate 10 is made sufficiently low. For this reason, the friction clutch mechanism constituted by the clutch plate 9, friction plate 10, etc. does not transmit torque, and the side gear 2 rotates freely with respect to the differential case 1, so that a differential operation is performed. Maneuverability of the vehicle is ensured. Note that in normal running conditions where differential restriction is not performed as described above, the side gear 2 is moved and held toward the center by the biasing force of the spring 17, and the backlash between the side gear 2 and the pinion 4 is substantially zero. . Therefore, the noise emitted from the actuating device as the vehicle travels is extremely low, and since the side gear is used as a moving part of the friction clutch mechanism, the number of component parts of the friction clutch mechanism can be reduced. You can also do that.

On the other hand, when the rotation difference between the left and right drive wheels becomes larger than a predetermined value, such as when one of the drive wheels gets stuck in a low-friction road surface, a signal from the controller 16 causes the electromagnetic three-way valve 15 to close the cylinder 11. The inside is switched and connected to the air tank 13. Then, the air in the air tank 13 flows through the pipe 14 to the cylinder 1.
1, the internal pressure of the cylinder 11 increases and a thrust force is generated that moves the piston 12 to the right in the figure.

Then, in response to this thrust, the piston 12 moves to the right in the figure, and in order to move the side gear 2 in the same direction, the distance between the positioning surface 7 of the side gear 2 and the support surface 8 of the differential case 1 is adjusted. becomes smaller, increasing the contact pressure between the clutch plate 9 and the friction plate 10, increasing the transmission torque of the friction clutch mechanism and increasing the frictional force between the side gear 2 and the differential case 1. Furthermore, since this frictional force increases as the internal pressure of the cylinder 11 increases, the degree of differential limiting action can be adjusted by controlling the internal pressure of the cylinder 11 to increase or decrease. Therefore, the cylinder 11 is adjusted depending on the degree of rotation difference between the left and right drive wheels (the degree of slip of the drive wheel on one side).
All you have to do is adjust the internal pressure.

On the other hand, the working fluid is also supplied to the cylinder 11 when the automobile is running at high speed and the steering angle is sufficiently small, that is, when it is detected that the vehicle is running at high speed in a straight line.
This performs a differential limiting action and improves straight-line performance. Furthermore, even when there is a possibility of entering a low-friction road surface, the working fluid is supplied to the cylinder 11 to perform differential limiting action, but in such cases and during the above-mentioned high-speed straight travel, the internal pressure of the cylinder 11 is maintained at an appropriate level. By lowering the degree of differential limiting action, it is desirable to improve the driving stability while ensuring the maneuverability of the vehicle.

In addition, by changing the frictional force between the side gear and the differential case, the OS-US characteristics (steering characteristics) of the vehicle can be changed.
The internal pressure of the cylinder 11 is changed according to the vehicle speed.
OS-US can also be optimally controlled according to vehicle speed.

Although air is used as the working fluid in the embodiment, the cylinder 11 can also be made smaller by using hydraulic pressure.

<Effects of the invention> As is clear from the above explanation, in the present invention, the control means variably controls the internal pressure of the cylinder in accordance with the rotation difference between the left and right drive wheels to change the frictional force between the side gear and the differential case. The degree of differential restriction is changed by Therefore, when driving with a small rotational difference between the left and right drive wheels, such as during normal driving, the biasing force of the spring moves and holds the side gear toward the center, so that the transmission torque of the friction clutch mechanism is sufficient. It becomes smaller and performs smooth differential operation. However, if the rotation difference between the left and right drive wheels becomes large due to one of the drive wheels getting stuck on a low-friction road surface and slipping, the differential function is automatically limited according to this rotation difference. Escape performance on low-friction road surfaces is improved, and sudden changes in torque due to differential differential restriction are prevented. Furthermore, by arbitrarily changing the external signal and appropriately adjusting the internal pressure of the cylinder, the degree of differential limiting action can be adjusted, making it possible to obtain OS-US characteristics according to the road surface or driving conditions. This makes it possible to improve both the maneuverability and running stability of the vehicle. Furthermore, by moving the side gear in the axial direction, the transmission torque of the friction clutch is changed to perform a differential limiting action, so the number of component parts of the friction clutch mechanism can be reduced. Moreover, in normal running conditions, the biasing force of the spring moves and holds the side gear toward the center, thereby reducing the bump crash to substantially zero, thereby effectively reducing the noise of the differential gear. You can also do that.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view of essential parts showing an embodiment of a variable limited slip differential for an automobile according to the present invention. 1...Differential case, 2...Side gear, 3...
Spider, 4...pinion, 5...ring gear,
6...Axle shaft, 7...Positioning surface, 8
... Support surface, 9 ... Clutch plate, 10 ... Friction plate, 11 ... Cylinder, 12 ... Piston, 13
... Source of working fluid, 14 ... Piping, 15 ...
Solenoid three-way valve, 16...controller.

Claims (1)

[Scope of utility model registration request] In an automobile in which a pair of side gears spline-fitted to an axle shaft are pivotally attached to a differential case, the side gears are pivotably attached to be movable in the axial direction, and a spring that biases the side gears to slide toward the center side of the differential case. A clutch plate engaged with the side gear in a non-rotating manner, a friction plate of the differential case with a non-rotating engagement, a piston inserted into a cylinder formed on the outer surface of the differential case, and a rotation difference between the left and right drive wheels. A friction clutch mechanism is provided, comprising a control means for controlling an increase or decrease of the internal pressure of the cylinder, and in which the clutch plate and the friction plate are alternately overlapped between a positioning surface formed on the outer surface of the side gear and a support surface provided on the inner surface of the differential case. , the side gear is coupled to the piston, and as the internal pressure of the cylinder increases, the side gear is moved outward against a spring to increase the transmission torque of the friction clutch mechanism. A variable limited slip differential for an automobile, which is characterized by: