JPH06115373A - Idler wheel differential limiting device of vehecle - Google Patents

Abstract

PURPOSE:To provide an idler wheel differential limiting device of a vehicle excellent in reliability and durability and capable of carrying out differential limiting in accordance with a travelling condition and carrying out differential limiting in accordance with a road surface mu. CONSTITUTION:So as to limit differential of left and right front wheels (idler wheels) of a rear wheel drive automobile, a pair of left and right shaft members 11a, 11b are arranged on axles 9a, 9b of left and right front wheels 8a, 8b respectively through adjustable joints 10a, 10b and a multiple disc viscous clutch 12 is provided between the both shaft members 11a, 11b, and by controlling a driving electric current to its solenoid 21 by a control unit 20, differential limiting in accordance with a travelling condition of the automobile 1 and simultaneously, as a road surface mu becomes low mu, differential limiting is relaxed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driven wheel differential limiting device for a vehicle, and more particularly to a differential limiting device for performing differential limiting according to a running state of the vehicle and performing differential limiting correction according to road surface μ. Regarding

[0002]

2. Description of the Related Art Generally, an automobile is provided with a pair of left and right driving wheels and a pair of left and right driven wheels. However, in a conventional automobile, in order to achieve smooth turning, there is a space between the left and right driving wheels. Although a differential device that allows differential is provided, the left and right driven wheels are configured to independently follow the road surface, and the differential limiting device that limits the differential between the left and right driven wheels is Not provided at all.

That is, the left and right driven wheels of a conventional automobile are
It simply supports the weight, secures posture stability, secures braking force, and achieves the function of sharing the turning lateral force.It also changes the steering characteristics and driving characteristics of the vehicle via the left and right driven wheels. It is not configured to let. Here, in Japanese Utility Model Application Laid-Open No. 61-94427, in order to improve the straight running stability of the vehicle, a differential limiting means including a multi-plate friction clutch is provided between the axles of the left and right driving wheels, and There is disclosed a vehicle axle device in which differential limiting means including the same multi-disc friction clutch as described above is provided between the axles.

[0004]

In the vehicle axle device of the above publication, since the differential limiting means composed of the multi-plate friction clutch is not configured to be controlled at all, the steer characteristic is understeered to improve straight running stability. Although it can be increased, there is a problem that the turning performance is extremely deteriorated. In particular, since it is not possible to limit the differential according to the magnitude of the friction coefficient μ of the road surface, it is difficult to secure the turning performance and traveling stability when traveling on a low μ road such as a snowy road. An object of the present invention is to provide a driven wheel differential limiting device for a vehicle, which can perform differential limiting according to a running state and can perform differential limiting according to a friction coefficient μ of a road surface.

[0005]

According to a first aspect of the present invention, there is provided a differential limiting device for a vehicle, wherein a left-right driven wheel differential is limited in a vehicle having a pair of left and right driving wheels and a left and right pair of driven wheels. Differential limiting means, a running state detecting means for detecting various physical quantities related to the running state of the vehicle, and a differential limiting according to the running state of the vehicle based on the output of the running state detecting means. The control means for controlling the differential limiting means, the road surface μ detecting means for detecting the friction coefficient μ of the road surface, and the output of the road surface μ detecting means, and the differential restriction is loosened in response to the low μ. Thus, the correction means for correcting the control amount in the control means is provided.

The driven wheel differential limiting device for a vehicle according to claim 2 is
In a vehicle including a pair of left and right driving wheels and a pair of left and right driven wheels, a differential limiting unit that limits a differential between the left and right driven wheels, and traveling that detects various physical quantities related to a traveling state of the vehicle. State detecting means, control means for controlling the differential limiting means so as to perform differential limiting according to the running state of the vehicle based on the output of the running state detecting means, and a road surface for detecting a friction coefficient μ of the road surface. In response to the μ detection means and the output of the road surface μ detection means, when traveling on a low μ road, the differential limit is not relaxed in the small steering angle region, and the differential limit is relaxed in the large steering angle region,
And a correction means for correcting the control amount in the control means.

[0007]

In the driven wheel differential limiting device for a vehicle according to the present invention, the differential limiting means limits the differential between the left and right driven wheels, and the running state detecting means sets the running state of the vehicle. The related physical quantities are detected, the control means controls the differential limiting means so as to perform the differential limiting according to the running state of the vehicle based on the output of the running state detecting means, and the road surface μ detecting means,
The friction coefficient μ of the road surface is detected, and the correction means receives the output of the road surface μ detection means and corrects the control amount in the control means so as to loosen the differential limitation as the μ becomes low. Here, the differential limitation according to the traveling state is, for example, a differential limitation in which the differential limitation is loosened as the steering angle increases or the differential limitation is strengthened as the vehicle speed increases. . The correction means corrects so that the differential limitation is relaxed as the value of μ decreases, so that it is possible to achieve both steering stability on high μ roads and low μ roads.

According to another aspect of the present invention, there is provided a driven wheel differential limiting device, which is a differential limiting device, a running condition detecting device, a control device,
The road surface μ detection means and the road surface μ detection means operate in the same manner as in claim 1. The correction means receives the output of the road surface μ detection means, and
When traveling on a road, the control amount in the control means is corrected so as not to loosen the differential limit in the small steering angle region and loosen the differential limit in the large steering angle region. In this way, by not loosening the differential limit in the small rudder angle range, the steering stability when driving at high speeds in the small rudder angle is enhanced, and by reducing the differential limit in the large rudder angle range, It is possible to prevent deterioration of turning performance when turning at an angle.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. This embodiment is an example in which the present invention is applied to a driven wheel differential limiting device (hereinafter referred to as a differential limiting device) of a rear wheel driving type automobile, and as shown in FIG. In an automobile 1, an engine 2 and an automatic transmission 3 are vertically arranged at a front portion of a vehicle body, and an output rotation from the automatic transmission 3 is generated by a drive shaft 5 and a pair of left and right rear wheels 6a and 6b.
Differential device 5 provided between the axles 7a and 7b of (driving wheels)
Is transmitted to the left and right axles 7a, 7b via.

A universal joint 10a, 1 capable of transmitting rotation is attached to the axles 9a, 9b of a pair of left and right front wheels 8a, 8b (driven wheels).
A pair of left and right axle members 11a and 11b are connected via 0b, respectively, and a multi-plate viscous clutch 12 of the differential limiting device is provided between the left and right axle members 11a and 11b (this corresponds to a differential limiting mechanism). And the left axle member 11a is
The shaft member of the multi-plate viscous clutch 12 is integrally connected, and the right axle member 11b is integrally connected to the case of the multi-plate viscous clutch 12. Incidentally, the steering wheel 14
The steering mechanism 14 coupled to the is also shown.

The differential limiting device includes left and right front wheels 8a, 8a.
This is for limiting the differential (rotational speed difference) of b according to the running state of the automobile 1. This differential limiting device includes the multi-disc viscous clutch 12, a control unit 20 for controlling the same, It is composed of various sensors 22 to 26 that detect various physical quantities related to the running state of the automobile. The multi-plate viscous clutch 12 includes a plurality of inner clutch plates fixed to its shaft member, a plurality of outer clutch plates arranged between the inner clutch plates and fixed to a case, and filled in the case. It is composed of an electromagnetic viscous fluid that exerts a viscous force between the inner clutch plate and the outer clutch plate, a solenoid 21 provided on one end side portion in the case, and the like. As the magnetic field applied to the electromagnetic viscous fluid by the solenoid 21 is strengthened, the viscosity of the electromagnetic viscous fluid is increased and the viscous force acting between the inner clutch plate and the outer clutch plate is strengthened, that is, the left and right sides. Front wheel 8a,
The differential limiting force for limiting the differential of 8b is strengthened.

The sensors include a steering angle sensor 22 for detecting a steering angle θh of a steering wheel, a vehicle speed sensor 23 for detecting a vehicle speed V of the automobile 1, a hydraulic pressure sensor 24 for detecting a brake hydraulic pressure P of a brake device, and a rough road. A vertical acceleration sensor 25 for detecting the vertical acceleration G of the vehicle body, a μ sensor 26 for detecting the friction coefficient μ of the road surface, etc. are provided for the determination, and detection signals of these sensors are supplied to the control unit 20.

The control unit 20 comprises an A / D converter for converting a detection signal, a waveform shaping circuit, an input / output interface, a microcomputer, a drive circuit for supplying a controlled drive current to the solenoid 21, and the like. A control program for differential limiting control, which will be described later, is input and stored in advance in the microcomputer. Here, the differential limiting device is provided to correct the running characteristics to the understeer side, improve the straight running stability at high speed running, and the steering stability during acceleration, and at the same time provide a differential according to the road surface μ. By restricting it, it enhances the driving stability of low μ road running,
This is to suppress slippage during braking and improve safety.

Next, a differential limiting control routine for controlling the differential limiting force in the multi-plate viscous clutch 12 of the differential limiting device according to the running state of the automobile 1 will be described with reference to the flow chart of FIG. explain. In FIG. 2, Si (i = 1, 2, ...) Indicates each step. When the control is started when the engine 2 of the automobile 1 is started,
In S1, various physical quantities (steering angle θh, vehicle speed V, brake oil pressure P,
The signals of vertical acceleration G and road surface μ) are read. next,
In S2, it is determined whether or not the vertical acceleration G is equal to or greater than a predetermined value, and whether or not the road on which the vehicle is running is a bad road. If it is not a bad road, the differential between the left and right front wheels 8a and 8b is limited in S3. The differential limiting force F is shown in the map (Map of FIG. 3).
(Θh, V)).

The map of FIG. 3 sets the differential limiting force F using the steering angle θh and the vehicle speed V as parameters, and ensures straight running stability during high speed running while ensuring turning performance during low speed running. In order to improve, the differential limiting force F is set to be smaller as the steering angle θh is increased, and the differential limiting force F is set to be larger as the vehicle speed V is increased. Here, in order to prevent the differential limiting force F from fluctuating as much as possible during high-speed traveling with a small steering angle, the change rate of the differential limiting force F is set to zero below a predetermined steering angle, and points a1, a2, and As indicated by a3, the predetermined steering angle is set to increase as the vehicle speed V increases. As a result, when traveling at high speed, the vehicle speed V
It is possible to improve the straight running stability according to the above and to enhance the understeer tendency to enhance the steering stability.

Further, the differential limiting force F when turning at a large steering angle
In order to prevent fluctuation of
The rate of change of the differential limiting force F is set to zero, and points b1, b2 and
As indicated by b3, the predetermined steering angle is set to increase as the vehicle speed V increases. This prevents fluctuations in turning performance when turning at a relatively low speed.

On the other hand, as a result of the determination in S2, when traveling on a rough road, the process proceeds to S4, and in S4, the differential limiting force F is calculated from the map (Map (G)) in FIG. 4, and at the same time, the correction coefficient F1, F2, F3, and F4 are all set to 1.0. The map of FIG. 4 sets the differential limiting force F in the region of the rough road where the vertical acceleration G is equal to or more than a predetermined value, and is set so that the differential limiting force F becomes smaller as the vertical acceleration G increases. There is. As a result, it is possible to ensure running performance on rough roads. After the calculation of S4, the process proceeds to S13. However,
The map of FIG. 4 may be set as a map having vertical acceleration G and vehicle speed V as parameters.

If the road is not a bad road, after the differential limiting force F is calculated in S3, the process proceeds to S5, and it is determined whether or not the braking state is based on the brake oil pressure P. If the braking state is present, the braking correction coefficient is determined in S6. When F1 is set to F1 = 1.2, and when the braking state is not established, the braking correction coefficient F1 is set to F in S7.
1 = 1.0 is set, and the process proceeds to S8. next,
In S8, the differential limiting force F is increased in response to the decrease of the road surface μ.
The road surface μ correction coefficient F3 for correcting the value is calculated from the map (Map (μ)) of FIG.

Next, in S9, it is judged whether or not the vehicle is in an accelerating state based on the rate of change of the vehicle speed V. If the vehicle is in an accelerating state, S1 is determined.
At 0, the acceleration correction coefficient F3 is set to F3 = 1.2, and when not in the acceleration state, the acceleration correction coefficient F3 is set to F3 = 1.0 at S11, and the process proceeds to S12. Next, in S12, the steering angular velocity correction coefficient F
4 is calculated from the map of FIG. The map of FIG. 6 sets the steering angular speed correction coefficient F4 to a value of 1.0 or less using the steering angular speed (dθ / dt) and the vehicle speed V as parameters, and the steering angular speed correction coefficient F4 is set according to the increase of the steering angular speed. F4 is set to be small, and the steering angular velocity correction coefficient F4 is set to be large as the vehicle speed V is increased. As a result, the differential limiting force F can be set small according to the steering angular velocity during turning, and the differential limiting force F can be set large according to the vehicle speed V.

After the calculation of S12, the target differential limiting force Ft is calculated by the following equation in S13. Ft = F × F1 × F2 × F3 × F4 Next, in S14, the target differential limiting force Ft is the predetermined value F.
It is determined whether or not it is less than c. If Ft <Fc, the process proceeds to S16.
t is set to Fc, and then the process proceeds to S16. The F
c is for clipping the target differential limiting force Ft in order to allow a slight differential even when maximum differential limiting is performed, but when differential is not allowed at all, high speed is achieved. This is because running stability is impaired due to slight irregularities on the road surface during running.

Next, in S16, a control signal based on the target differential limiting force Ft set in S13 is output to the drive circuit of the solenoid 21, and a drive current is output from the drive circuit to the solenoid 21. After that, the process returns and the steps S1 to S16 are repeated. As a result, the differential limiting force of the multi-plate viscous clutch 12 is controlled so as to become the target differential limiting force Ft, and the differential limiting for limiting the differential between the left and right front wheels 8a and 8b is performed. Incidentally, S6, S10
The value of "1.2" shown in is only a value showing an example, and is not limited to this value.

Next, the operation of the driven wheel differential limiting device for an automobile described above will be described. Since the multi-plate viscous clutch 12 is configured to transmit the differential limiting force via the electromagnetic viscous fluid, the clutch plate does not wear,
The characteristics do not change due to the wear of the clutch plate, and it has excellent reliability and durability. Further, as set in the map of FIG. 3, since the differential limitation is relaxed in accordance with the increase of the steering angle θh,
It is possible to secure the turning performance when winding on a mountain pass or turning at an intersection or the like.

At the same time, when the vehicle speed is lower than 40 km / h, the differential limitation is not performed, and the differential limitation is strengthened in accordance with the increase of the vehicle speed V, so that the turning performance at low speed is secured and the straight running stability at high speed is secured. It is possible to increase the running stability by increasing the understeer tendency. Furthermore, when going straight (steering angle θh =
0) is subjected to maximum differential limitation, and S in FIG.
Since the target differential limiting force Ft is clipped via 14 and S15 to allow a slight differential even at the maximum differential limiting during high-speed traveling, straight running stability during straight running is achieved. It is possible to prevent the deterioration of the running stability due to the unevenness of the road surface while extremely improving the

Further, since the points a1, a2, and a3 in FIG. 3 are sequentially shifted toward the larger steering angle, the range in which the differential limiting force does not change during high speed traveling at a small steering angle is widened, and the range during high speed traveling is increased. Stability can be secured. Since the points b3, b2, and b1 in FIG. 3 are sequentially shifted toward the smaller steering angle, it is possible to secure the turning stability by widening the range in which the differential limiting force does not change at the low speed and large steering angle. By loosening the differential limitation when traveling on a rough road, the running performance on a rough road can be enhanced.

Further, since the differential limiting force F is corrected to become smaller as the road surface μ becomes lower μ, the steering stability at the time of traveling on a low μ road such as a snow road or a wet road surface is improved. It is possible to achieve both steering stability when traveling on a high μ road. Further, by increasing the differential limitation during acceleration, it is possible to reduce the oversteer tendency in a rear-wheel drive vehicle that has a strong oversteer tendency.

Here, instead of the map of FIG. 5, the road surface μ correction coefficient F3 may be set based on the map of FIG. That is, in the map of FIG. 7, the road surface μ correction coefficient F3 is set to 1.0 for the high μ road where the road surface μ is larger than the predetermined value μ0. On the other hand, for a low μ road where the road surface μ is a predetermined value μ0 or less, the road surface μ correction coefficient F3 is set to 1.0 in the small steering angle region, as shown by the solid line in the figure, and In the large steering angle region, the road surface μ correction coefficient F3 is set to be significantly smaller than 1.0. When the road surface μ correction coefficient F3 is set in this way,
Understeering can be achieved during high-speed traveling with a small steering angle to improve straight-line stability, and turning characteristics can be secured during traveling with a large steering angle. However, the map of FIG. 7 may be a map in which the road surface μ is divided into a plurality of stages.

First Alternative Embodiment Next, an embodiment in which a part of the above embodiment is modified will be described. The present embodiment relates to a driven wheel differential limiting device that limits the differential between the left and right rear wheels of a front-wheel drive type automobile, and as shown in FIG. A power unit 33 including an engine and an automatic transmission is horizontally disposed between the axles 32a and 32b of the front wheels 31a and 31b, and a steering handle 34 and a steering mechanism 35 connected thereto are also illustrated.

A pair of left and right rear wheels 36a, 36b (driven wheels)
A multi-disc viscous clutch 38 similar to the multi-disc viscous clutch 12 is laterally disposed between the axles 37a, 37b of the left side wheel, and the axle 37a of the left rear wheel 36a is integrally connected to the shaft member of the multi-disc viscous clutch 38. Further, the axle 37b of the right rear wheel 36b is integrally connected to the case of the multi-plate viscous clutch 38, and the left and right rear wheels 3 are
It is configured so that the differential between 6a and 36b can be limited.
The multi-plate viscous clutch 38, like the multi-plate viscous clutch 12, is configured to be filled with an electromagnetic viscous fluid. The left and right rear wheels 36 depending on the running state of the automobile 30
The differential limiting device for limiting the differential between a and 36b includes a multi-plate viscous clutch 38, a control unit 39, and sensors similar to those in the above-described embodiment.

The control routine for controlling the solenoid of the multi-plate viscous clutch 38 by the control unit 39 is as follows.
The description is omitted because it is the same as the above-mentioned embodiment. However, in the front-wheel drive type vehicle 30, the running characteristics tend to be understeer. Therefore, in order to mitigate the understeer tendency during acceleration, the acceleration correction coefficient F3 is set to F3 = 0.8 in S10 of FIG. It The operation and effect of the above-described differential limiting device is basically the same as that of the above-described embodiment, and therefore description thereof will be omitted.

Second Alternative Embodiment Next, an embodiment of a differential limiting device for limiting the differential between the left and right rear wheels of a front-wheel drive type automobile through fluid pressure or fluid force will be described. As shown in FIG. 9, in a front-wheel drive type automobile 40, a pair of left and right front wheels 41a and 41b, a power unit 42, a steering handle 43, a steering mechanism 44, etc. are provided in the same manner as in the first embodiment. Has been.

Further, a pair of left and right hydraulic pumps / motors 47a, 47b fixed to the vehicle body are provided as differential limiting means for limiting the differential between the left and right rear wheels 45a, 45b via fluid pressure or fluid force. And its shaft members are hydraulic pumps / motors 47a and 47b connected to the axles 46a and 46b of the left and right rear wheels 45a and 45b, respectively, and the discharge port 48a of the left hydraulic pump / motor 47a and the right side. Hydraulic pump/
An oil passage 50 connecting to the suction port 49b of the motor 47b,
An oil passage 51 connecting the discharge port 48b of the right hydraulic pump / motor 47b and the suction port 49a of the left hydraulic pump / motor 47a, and an oil passage 50 and an oil passage 51 near the left hydraulic pump / motor 47a. And a control valve 52a interposed in an oil passage connecting the hydraulic pump / motor 4 on the right side.
A control valve 52b provided in an oil passage connecting the oil passage 50 and the oil passage 51 is provided near 7b.
The control valves 52a and 52b are configured so that their flow rates can be electrically controlled. The differential limiting device is composed of the differential limiting means, a control unit 53, and sensors similar to those in the above-described embodiment, and the control unit 53 has a left side and a right side depending on a traveling state detected by the sensors. The control valves 52a and 52b are controlled to perform differential limiting control.

Explaining the operation of this differential limiting device, when the left and right control valves 52a and 52b are kept fully closed, the entire amount of oil discharged from the hydraulic pump / motor 47a is sucked into the hydraulic pump / motor 47b. Also, since the entire amount of oil discharged from the hydraulic pump / motor 47b is sucked into the hydraulic pump / motor 47a, the left and right rear wheels 4
When there is no differential between 5a and 45b, both hydraulic pumps /
The motors 47a, 47b rotate with almost no resistance, but when a differential occurs between the left and right rear wheels 45a, 45b, fluid resistance in the direction of eliminating the differential acts to limit the differential. When both control valves 52a and 52b are opened, a flow rate of oil flows according to the opening degree, so that the differential limiting action decreases according to the opening degree. When both control valves 52a and 52b are fully opened, the entire amount of hydraulic pressure discharged from the hydraulic pump / motor 47a is sucked into the hydraulic pump / motor 47a via the control valve 52a, and the hydraulic pump / motor 47b is also supplied.
Since the entire amount of hydraulic pressure discharged from the pump is sucked into the hydraulic pump / motor 47b via the control valve 52b, the differential limiting action cannot be obtained.

Therefore, the differential limiting force can be changed from the maximum range to the minimum range by controlling the opening degrees of both the control valves 52a and 52b in the range from fully closed to fully open. The control characteristic of controlling both control valves 52a and 52b by the control unit 53 is the same as that of the above-mentioned embodiment, and therefore its explanation is omitted. As the hydraulic pumps / motors 47a and 47b, for example, vane pumps / motors and other hydraulic pumps / motors can be applied, and the effect of oil viscosity due to oil temperature may be compensated.

In the differential limiting device of this embodiment, the hydraulic pumps / motors 47a and 47b are connected to the left and right rear wheels 45a and 45b.
Since it can be placed close to the vehicle, it can be placed without any restrictions on the space in the center of the vehicle body, which is advantageous in terms of layout, and because it is configured to be differentially limited by fluid pressure or fluid force, wear of the clutch plate etc. occurs. It has excellent reliability and durability.

Third Embodiment Next, another embodiment of the differential limiting device for limiting the differential between the left and right rear wheels of a front-wheel drive type automobile by means of fluid pressure or fluid force will be described. As shown in FIG. 10, a front wheel drive type automobile 60 is provided with a pair of left and right front wheels 61a and 61b, a power unit 62, a steering handle 63, a steering mechanism 64, and the like, as in the first embodiment.

Further, a pair of left and right hydraulic pumps / motors 67a, 67b fixed to the vehicle body are provided as a differential limiting means for limiting the differential between the left and right rear wheels 65a, 65b via fluid pressure or fluid force. And its shaft members are hydraulic pumps / motors 67a, 67b connected to the axles 66a, 66b of the left and right rear wheels 65a, 65b, respectively, and a discharge port 68a and a suction port 69a of the hydraulic pump / motor 67a. Oil passage 70a for connecting the discharge port 68 of the hydraulic pump / motor 67b
b and the oil passage 70b connecting the suction port 69b and the oil passage 7b
A pair of left and right control valves 7 which are respectively installed in 0a and 70b
1a and 71b are provided.

In each of the hydraulic pumps / motors 67a and 67b, if the control valves 71a and 71b are held in the fully opened state, the entire amount of the discharged oil is sucked into the same hydraulic pump / motor, so that the differential limiting action is completely obtained. However, if the opening of the control valve 71a is reduced, fluid resistance acts on the hydraulic pump / motor 67a, and if the opening of the control valve 71b is reduced, fluid resistance acts on the hydraulic pump / motor 67b. Become.

Therefore, the control unit 72 controls the control valves 71a and 71b in accordance with the traveling state detected by the sensors, so that the rear wheel 6 having the higher rotational speed can be controlled.
5a or the rear wheel 65b corresponding to the control valve 71a or the control valve 71b is throttled to reduce the rotational speed of the rear wheel 65a or the rear wheel 65b having a higher rotational speed,
The differential between the left and right rear wheels 65a and 65b can be limited. The control characteristic of differentially limiting the right and left control valves 70 is basically the same as that of the above-described embodiment, and therefore the description thereof is omitted. According to the differential limiting device of this embodiment, the same action and effect as those of the second alternative embodiment can be obtained.

Fourth Alternative Embodiment Next, an embodiment of a differential limiting device constructed so as to limit the differential between the left and right rear wheels of a front-wheel drive type automobile through a brake unit for the left and right rear wheels explain. As shown in FIG. 11, in a front-wheel drive type automobile 80, left and right front wheels 81a and 81b and a power unit 8 are provided in front of the automobile 80.
2, a steering handle 83, a steering mechanism 84 and the like are provided.

The brake device for braking the left and right rear wheels 85a, 85b will be described. The brake discs 87a, 87b of the brake device are respectively provided on the axles 86a, 86b of the left and right rear wheels 85a, 85b. The brake disks 87a and 87b are fixedly connected to each other, and calipers 88a and 88b are attached to the brake discs 87a and 88b, respectively. 91 and is supplied to the hydraulic cylinders of the left and right calipers 88a and 88b from the master cylinder 91, respectively. The above braking device has a general structure provided in a normal automobile.

Here, in the differential limiting device of this embodiment, the left and right brake discs 87 are used as the differential limiting means.
auxiliary calipers 92a and 9a attached to a and 87b, respectively
2b and a hydraulic pressure supply device 93 that supplies hydraulic pressure to these auxiliary calipers 92a and 92b. However,
The auxiliary calipers 92a and 92b are provided so that when the hydraulic pressure is supplied from the hydraulic pressure supply device 93 to the hydraulic cylinders of the left and right calipers 88a and 88b to limit the differential, the left and right calipers 88a and 88a are This is because the hydraulic pressure of the hydraulic cylinder 88b cannot be kept constant and the braking performance of the brake device fluctuates, which is to be prevented.

The hydraulic pressure supply device 93 includes an electric motor 94.
A hydraulic pump 95 driven by, a distribution valve 96 for distributing the hydraulic pressure generated by the hydraulic pump 95, an oil passage 98a extending from the distribution valve 96 and connected to a hydraulic cylinder of an auxiliary caliper 92a on the left side, and a distribution valve The oil passage 98b extends from 96 and is connected to the hydraulic cylinder of the auxiliary caliper 92b on the right side, and the control valves 97a and 97b interposed in the oil passages 98a and 98b, respectively. Therefore, by controlling the hydraulic pressures of the hydraulic cylinders of the left and right auxiliary calipers 92a and 92b via both control valves 97a and 97b, the differential limitation of the left and right rear wheels 85a and 85b can be performed.

As described above, the differential limiting device includes the pair of left and right auxiliary calipers 92a and 92b attached to the pair of left and right brake discs 87a and 87b, the hydraulic pressure supply device 93, and the control valves 97a and 97b. The control unit 99 includes a control unit 99 for controlling the vehicle and sensors similar to those in the above-described embodiment.
The differential limitation for the left and right rear wheels is performed by controlling. However, the control characteristic of the differential limitation control is the same as that of the above-described embodiment, and therefore the description thereof is omitted.

Fifth Alternative Example Next, an example of a differential limiting device to which a multi-plate friction clutch is applied will be described. As shown in FIG. 12, a differential limiting device for limiting the differential between the left and right rear wheels of a front-wheel drive type automobile includes a hydraulically-biased multi-plate friction clutch 100, a hydraulic supply device 101, and a control device. It is composed of the unit 102. The hydraulically biased multi-plate friction clutch 100 will be described. The case 103 is integrally connected to the axle 105 of the left rear wheel, and the shaft member 10 is provided.
4 is integrally connected to the axle 106 of the right rear wheel, a plurality of inner clutch plates 107 are spline-fitted to the shaft member 104 in the case 103, and the inner clutch plates 107 are arranged between the inner clutch plates 107 in the case 103. A plurality of positioned outer clutch plates 108 are spline-fitted to the inner peripheral portion of the case 103, and further, a disc spring 109 and a piston member 11 are provided.
0 is provided as shown in the drawing, and the hydraulic pressure supply device 101 is provided in the oil chamber 111 on the right side of the piston 110 in the case 103.
The hydraulic pressure is supplied from the control unit, and the hydraulic pressure in the oil chamber 111 is controlled to limit the differential between the shaft member 105 and the shaft member 106. The disc spring 109 can be omitted.

The hydraulic pressure supply device 101 includes an electric motor 112.
The hydraulic pump 113 is driven by an oil passage, an oil passage 114 extending from its discharge port and connected to the oil chamber 111, and a control valve 115 interposed in the oil passage 114. The control valve 115 is a control unit. Controlled by 102. When the oil pressure in the oil chamber 111 is sufficiently low, the frictional force does not act between the inner clutch plate 107 and the outer clutch plate 108, so that the differential limiting action cannot be obtained. Since a frictional force acts between the inner clutch plate 107 and the outer clutch plate 108 according to the hydraulic pressure, a differential limiting action is obtained.

Since the control characteristic of the differential limiting control performed by the control unit 102 is basically the same as that of the above-mentioned embodiment, the description thereof will be omitted. The differential limiting device can also be applied to limit the differential between the left and right front wheels of a rear-wheel drive vehicle. Incidentally, the multi-plate friction clutch 1
In place of 00, an electromagnetic clutch having a mechanism for transmitting the fastening force by frictional contact between the friction plates is provided, and the electromagnetic clutch is configured so that the fastening force can be changed according to the magnitude of the drive current supplied to it. The differential limiting force may be controlled by controlling the drive current supplied to the electromagnetic clutch.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a driven wheel differential limiting device for a rear wheel drive type automobile according to an embodiment.

FIG. 2 is a flowchart of a differential limiting control of the differential limiting device in FIG.

FIG. 3 is a diagram of a map of differential limiting force.

FIG. 4 is a diagram of a map of differential limiting force.

FIG. 5 is a diagram of a map of a road surface μ correction coefficient.

FIG. 6 is a diagram of a map of steering angular velocity correction coefficients.

FIG. 7 is a diagram of a map of road surface μ correction coefficient.

FIG. 8 is a configuration diagram of a driven wheel differential limiting device for a front wheel drive type automobile according to a first alternative embodiment.

FIG. 9 is a configuration diagram of a driven wheel differential limiting device for a front wheel drive type automobile according to a second alternative embodiment.

FIG. 10 is a configuration diagram of a driven wheel differential limiting device for a front wheel drive type automobile according to a third embodiment.

FIG. 11 is a configuration diagram of a driven wheel differential limiting device for a front wheel drive type automobile according to a fourth alternative embodiment.

FIG. 12 is a configuration diagram of a differential limiting device according to a fifth alternative embodiment.

[Explanation of symbols]

 8a, 8b Front wheel 9a, 9b Axle 12 Multi-plate viscous clutch 20 Control unit 22-26 Sensors 36a, 36b Rear wheel 37a, 37b Axle 38 Multi-plate viscous clutch 39 Control unit 45a, 45b Rear wheel 46a, 46b Axle 47a, 47b Hydraulic pump / motor 50,51 Oil passage 52a, 52b Control valve 53 Control unit 65a, 65b Rear wheels 66a, 66b Axle 67a, 67b Hydraulic pump / motor 70a, 70b Oil passage 71a, 71b Control valve 72 Control unit 85a, 85b Rear Wheel 86a, 86b Axle 87a, 87b Caliper 92a, 92b Auxiliary caliper 93 Hydraulic supply device 97a, 97b Control valve 99 Control unit 100 Hydraulically energized multi-disc friction clutch 101 Oil Feeder 102 control unit 115 control valve

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takao Imada 3-1, Shinchi, Fuchu-cho, Aki-gun, Hiroshima Prefecture Mazda Motor Corporation

Claims (2)

[Claims] 1. A vehicle having a pair of left and right driving wheels and a pair of left and right driven wheels, differential limiting means for limiting a differential between the left and right driven wheels, and various elements related to a traveling state of the vehicle. A running state detecting means for detecting a physical quantity, a control means for controlling the differential limiting means so as to perform a differential limiting according to the running state of the vehicle based on the output of the running state detecting means, and a friction coefficient of a road surface. a road surface μ detection means for detecting μ, and a correction means for receiving the output of the road surface μ detection means and correcting the control amount in the control means so as to loosen the differential limitation in response to a low μ, A driven wheel differential limiting device for a vehicle, comprising: 2. A vehicle provided with a pair of left and right driving wheels and a pair of left and right driven wheels, a differential limiting means for limiting a differential between the left and right driven wheels, and various elements related to a traveling state of the vehicle. A running state detecting means for detecting a physical quantity, a control means for controlling the differential limiting means so as to perform a differential limiting according to the running state of the vehicle based on the output of the running state detecting means, and a friction coefficient of a road surface. In response to the road surface μ detecting means for detecting μ and the output of the road surface μ detecting means, when traveling on a low μ road, the differential limit is not relaxed in the small steering angle region, and the differential limit is set in the large steering angle region. A driven wheel differential limiting device for a vehicle, comprising: a correction unit that corrects a control amount in the control unit so as to be loosened.