JPH0585135A - Suspension device for vehicle - Google Patents

Abstract

PURPOSE:To improve both the performance of running the whole distance of a bad road and the running stability during the normal running effectively by varying the roll rigidity of a vehicle in a simple constitution. CONSTITUTION:Coil springs 22, 23 and pneumatic dampers 24,25 are arranged side by side corresponding to right and left wheels 3FL, 3FR, respectively. Air chambers 24a, 25a of both pneumatic dampers 24, 25 are connected to each other by a communicating path 31, and a cut-off valve 32 is disposed in the communicating path 31. Under the control of a control unit 11, during running on a bad road, the cut-off valve 32 is opened to lower the roll rigidity of a vehicle, and during normal running, the cut-off valve 32 is closed to increase the roll rigidity of the vehicle. Though the cut-off valve 32 is also opened during rectilinear running of the vehicle, the communicating resistance at that time is made larger than that during running on a bad road.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle suspension device, and more particularly to a suspension device having a mechanical spring means and a fluid damper.

[0002]

2. Description of the Related Art Generally, a vehicle suspension system is
A two-degree-of-freedom system is configured for vertical vibration, and a mechanical spring means such as a coil spring or a leaf spring and a shock absorber or the like are provided between an unsprung part (vehicle body side) and an unsprung part (wheel side). A fluid damper is disposed in parallel (see Japanese Utility Model Laid-Open No. 63-189705).

On the other hand, the traveling stability during normal traveling, for example, when traveling at high speed on a highway, and the operating performance when traveling on a bad road, for example, when traveling at a low speed on a road where many rocks are exposed such as a riverbed or a mountain road. However, when attention is paid to the roll rigidity of the suspension, opposite characteristics are required. In other words, in order to ensure running stability during high-speed running, the roll rigidity should be increased to maintain the vehicle body posture strongly, and to maintain a high level against lateral force when receiving a side wind or turning a curve. Required to be able to. On the other hand, in order to ensure running performance on rough roads, roll rigidity can be lowered to prevent rolling of the vehicle body, the suspension stroke can be effectively pulled out, and the ground load on both wheels can be stabilized. Required to do so.

[0004]

However, the above-mentioned conventional suspension device employs the rigid type suspension device. Therefore, if the running stability is ensured at high speed running, the running performance on rough roads is improved. On the other hand, if an attempt is made to improve the running performance on a bad road, the running stability at high speed running will be deteriorated.

Therefore, the inventors of the present invention have previously proposed a new suspension device for improving both the running stability at high speed running and the running performance on rough roads (Japanese Patent Application No. 3-103).
61539). Specifically, the proposed suspension device includes first and second air spring type dampers provided corresponding to the left and right wheels, respectively, and a spring in a vehicle width direction central portion corresponding to the both dampers. A third air-spring damper of variable air pressure that elastically supports the upper part is provided, and during normal traveling, the air pressure of the third air-spring damper is set to zero to enhance the roll rigidity of the vehicle and travel on rough roads. At this time, the air pressure of the third air spring damper is maintained at a predetermined value to weaken the roll rigidity of the vehicle.
However, in the proposal, three expensive air spring type dampers are required for each of the front wheel side and the rear wheel side of the vehicle, which is disadvantageous in terms of cost.

The present invention has been made in view of the above points, and an object of the present invention is to make the roll rigidity of a vehicle variable by a simple structure, to drive on rough roads and to stabilize running during normal running. It is intended to provide a suspension device for a vehicle, which can effectively improve both the property and the property.

[0007]

In order to achieve the above object, the invention according to claim 1 is a suspension device for a vehicle, comprising a pair of left and right mechanical spring means provided corresponding to the left and right wheels respectively. A fluid damper arranged in parallel with each of the spring means, a communication passage communicating the fluid chambers of the fluid dampers, a shutoff valve provided in the communication passage, and a road surface on which the vehicle travels. A bad road determining means for judging that the road is a bad road and a control means for receiving a signal from the bad road judging means and controlling to open the shut-off valve at least during traveling on a bad road are provided.

The invention according to claim 2 is dependent on the invention according to claim 1, and in addition to the constituent elements thereof, further comprises a straight running detection means for detecting the straight running time of the vehicle. And
The shutoff valve is provided such that the communication resistance can be changed in at least two stages in an open state in which the communication passage is in communication. In the control means, the signal from the straight road detection means is received together with the signal from the rough road determination means, the shutoff valve is opened during traveling on a rough road and straight ahead, and the communication resistance at the shutoff valve is It is configured to be smaller when traveling on a rough road than when traveling straight.

An invention according to claim 3 is dependent on the invention according to claim 1, and further comprises a vehicle speed sensor for detecting a vehicle speed in addition to the constituent features thereof. The control means receives the signal from the vehicle speed sensor together with the signal from the rough road determination means, and closes the shutoff valve when the vehicle speed is equal to or higher than a predetermined speed even when traveling on a rough road.

[0010]

With the above construction, in the invention according to claim 1,
Under control of the control means, when traveling on a rough road, the shutoff valve is opened, the fluid chambers of the left and right fluid dampers communicate with each other through the communication passage, and the volume doubles. Will be lower. As a result, the grounding property of the wheel is enhanced, and the running performance on rough roads is improved. On the other hand, when the vehicle is not traveling on a rough road, the shutoff valve shuts off the communication passage, so that the roll rigidity of the vehicle is increased and the running stability is improved.

According to the second aspect of the invention, the shutoff valve is opened not only when traveling on a rough road but also when traveling straight, and the fluid chambers of the left and right fluid dampers communicate with each other through the communication passage. , The roll rigidity of the vehicle becomes low, and the riding comfort becomes good.

Further, according to the third aspect of the present invention, even when traveling on a rough road, when the vehicle speed is equal to or higher than a predetermined speed, the shutoff valve is closed to shut off the communication passage, so that high roll rigidity ensures traveling stability. become.

[0013]

Embodiments of the present invention will be described below with reference to the drawings.

1 to 3 show a vehicle suspension device 1 according to an embodiment of the present invention. As shown schematically in FIG. 1, this suspension device 1 is a device for suspending a vehicle body 2 on a total of four wheels in front, rear, left and right,
A front suspension device 1A for suspending the front portion of the vehicle body 2 on the left and right front wheels 3FL, 3FR (see FIGS. 2 and 3), and a rear portion of the vehicle body 2 on the left and right rear wheels 4RL (right rear wheel is not shown). And a rear suspension device 1B for suspending the vehicle.

The above suspension devices 1A and 1B are
Although the configuration will be described in detail later, the suspension device 1 includes the shock absorbers 5A and 5B having a plurality of air spring dampers, and the suspension device 1 includes the air supply device in order to introduce compressed air into the air spring dampers. 6 is provided in the vehicle body 2. The air supply device 6 includes an air pump 7 driven by an engine (not shown), an accumulator 8 for temporarily storing compressed air discharged from the air pump 7,
It is composed of valve mechanisms 9A and 9B for appropriately supplying the compressed air accumulated in the accumulator 8 to the front and rear suspension devices 1A and 1B. The air pump 7 and the valve mechanisms 9A and 9B are both connected to a control unit 11 as a control means, and are drive-controlled under the control of the control unit 11.

Further, 12 is a vehicle speed sensor for detecting the vehicle speed,
Reference numerals 13A and 13B denote vehicle height sensors that detect the vehicle heights of the front wheel side and the rear wheel side, respectively, and 14 denotes a steering angle sensor that detects the steering angle of the steering wheel. The steering angle sensor 14 has a steering wheel steering angle of substantially zero. By having a certain time when the vehicle is traveling straight, the vehicle has a function as a straight traveling detection unit. The detection signals of these various sensors 12 to 14 are sent to the control unit 11 described above.
Is supplied to the valve 11 and is used for switching control of the valve mechanisms 9A and 9B by the unit 11.

Further, reference numeral 16 denotes a manual switch provided at a position accessible by a driver sitting in a driver's seat such as an instrument panel.
Is for manually switching the suspension devices 10A and 10B between a bad road running mode and a normal running mode other than this by a driver. When the suspension device 10A, 10B is turned on, the bad road running mode is turned off, and the normal running mode is turned off. Each mode is set manually. Therefore, the manual switch 16 has a function as a bad road judging means for judging that the road surface on which the vehicle is traveling is a bad road, and the mode setting information and thus the bad road judging information by the manual switch 16 are Control unit 11
Entered in. In this embodiment, the vehicle is configured as a four-wheel drive vehicle, and is equipped with an auxiliary transmission (not shown) for switching between the rear wheel drive mode and the four-wheel drive mode.

Next, referring to FIGS. 2 and 3, the structure of the front and rear suspension devices 1A and 1B will be described in detail. In the present embodiment, as described above, the vehicle is a four-wheel drive vehicle, so the front side and rear side suspension devices 1A and 1B have substantially the same configuration with respect to the features of the present invention. Therefore, in the following description, the front suspension device 1A will be described.
Of the rear suspension device 1B, and the suspension device 1A will be simply described.
Shall be abbreviated.

That is, as shown in FIGS. 2 and 3, the suspension device 1A includes left and right wheels (front wheels) 3F.
An axle housing 21 extending along the vehicle width direction between L and 3FR is provided. Inside the axle housing 21, a final gear, a differential device, and an axle shaft, which are not shown, are built in. They are integrally assembled to form a well-known rigid axle type (that is, fixed axle type) suspension device. As is well known, the left and right wheels 3FL and 3FR are connected to both ends of the axle shaft via wheel supports (not shown), and the wheels 3FL and 3FR are driven according to the rotation of the axle shaft. It is supposed to be done.

On the other hand, the front side shock absorber 5A is provided at both ends of the axle housing 21, that is, the left and right wheels 3.
First and second coil springs 22, 23 as mechanical spring means for elastically supporting the front part of the vehicle body 2 at positions corresponding to FL, 3FR, and these first and second coil springs 22, 23, and first and second air spring type dampers 24 and 25 as fluid type dampers that are respectively provided in parallel with each other and that dampen the vertical vibration of the sprung body (vehicle body 2). The air spring dampers 24 and 25 are configured such that their respective damping coefficients are set to arbitrary values according to the pressure in the air chambers (fluid chambers) 24a and 25a, that is, the air pressure. Since its configuration is well known, its description is omitted.

Further, the valve mechanism 9A constituting the air supply device 6 includes the first and second air spring dampers 2 described above.
It is provided with first and second control valves 26 and 27 which are provided corresponding to 4 and 25, respectively. Both control valves 26, 2
7 receives the control signal from the control unit 11,
It is designed to be driven and controlled. Here, each control valve 2
6 and 27 connect the air chambers 24a and 25a of the corresponding air spring dampers 24 and 25 to the accumulator 8 to increase the internal pressure, and the air chambers 24a of the corresponding air spring dampers 24 and 25. , 25a is closed to keep the internal air pressure, and the corresponding air spring dampers 24, 25 are moved to an open position where the air chambers 24a, 25a of the dampers 24, 25 are opened to the atmosphere to lower the internal pressure. It is provided so that it can be moved and driven to a predetermined position and held at that position based on a control signal from the control unit 11. The control unit 1
1 is set so that the control amounts of the first and second control valves 26 and 27 are the same in order to maintain the left-right balance of the vehicle body 2.

Further, the air chambers 24a, 25a of the first and second air spring type dampers 24, 25 are communicated with each other through a communication passage 31, and a shutoff valve 32 is provided in the communication passage 31. Has been done. The shutoff valve 32 has a communication passage 31.
And a first communication position A having a closed position for shutting off the communication passage and a large throttle that opens the communication passage 31 and generates a relatively large communication resistance.
And a second communication position B having a small throttle that opens the communication passage 31 and generates a relatively small communication resistance. The control unit 11 is provided in the same manner as the control valves 26 and 27. On the basis of a control signal from the device, it is moved and driven to a predetermined position and held at that position.

The switching of the position of the shutoff valve 32 by the control unit 11 is performed according to the control flow shown in FIG.

That is, after starting, first of all,
In step S1, it is determined based on the signal from the vehicle speed sensor 12 whether or not the vehicle speed is equal to or lower than a predetermined value (for example, 10 km / h).
In step 2, it is determined based on the signal from the manual switch 16 whether the traveling road surface is a bad road. Then, if this determination is YES, the shutoff valve 32 is switched to the second communication position B in step S3, and the communication passage 31 is made to communicate in a state where a relatively small communication resistance is generated (communication B), and thereafter. To return.

On the other hand, when the determination in step S1 or S2 is NO, it is determined in step S4 based on the signal from the steering angle sensor 14 whether the vehicle is traveling straight ahead. When the vehicle is traveling straight ahead with the determination being YES, the shutoff valve 32 is switched to the first communication position A in step S5, and the communication passage 31 is communicated in a state where a relatively large communication resistance is generated (communication A). , And then return. On the other hand, if the determination is NO, the shutoff valve 32 is switched to the closed position to shut off the communication passage 31 in step S6, and thereafter the process returns.

Next, the operation of the above embodiment, particularly the operation associated with the position switching of the shutoff valve 32 under the control of the control unit 11 will be described.

When traveling at a low vehicle speed (10 km / h or less) on a bad road such as a riverbed or a mountain road where many rocks are exposed, the shut-off valve 32 is switched to the second communication position B, and the left and right air flows. The air chambers 24a, 25a of the spring dampers 24, 25 communicate with each other through the communication passage 31 and the volume doubles, so that the roll rigidity of the vehicle becomes low. Therefore, it is possible to improve the grounding property of the wheels 3FL and 3FR,
It is possible to improve running performance on rough roads.

When traveling straight on a general road,
The shutoff valve 32 is switched to the first communication position A, and the air chambers 24a and 25a of the left and right air spring dampers 24 and 25 are changed.
By communicating with each other through the communication passage 31,
The roll rigidity of the vehicle becomes low. Therefore, it is possible to prevent the rugged feeling due to the road surface projection or the like from being transmitted to the vehicle body, and it is possible to improve the riding comfort.

Here, when the first communication position A and the second communication position B of the shutoff valve 32 are compared, the communication resistance is large at the first communication position A and at the second communication position. Is set to be small, the roll rigidity becomes lower when traveling on a bad road where the second communication position B is switched to, compared to when traveling straight on an ordinary road. Therefore, it is possible to improve the running performance on rough roads and the riding comfort when traveling straight ahead at a high level.

On the other hand, when the vehicle travels on an ordinary road, the shutoff valve 32 is switched to the closed position to shut off the communication passage 31, so that the roll rigidity of the vehicle is increased.
Therefore, the posture of the vehicle body can be strongly maintained, and the running stability can be improved.

As described above, the roll rigidity of the vehicle can be changed by changing the air chamber 24 of the left and right air spring dampers 24, 25.
Since a and 25a are communicated with each other through the communication passage 31 and the shutoff valve 32 is provided in the communication passage 31, it can be implemented at low cost.
It is very advantageous for implementation.

The present invention is not limited to the above embodiment, but includes various other modifications.
For example, in the above embodiment, the determining means for determining whether the road surface on which the vehicle is traveling is a bad road is constituted by the manual switch 16 operated by the driver. However, instead of the manual switch 16, the vertical acceleration of the vehicle body is changed. May be detected by a sensor, and the rough road may be determined based on the detected value.

[0033]

As described above, according to the vehicle suspension device of the first aspect of the present invention, the fluid chambers of the left and right fluid dampers communicate with each other through the communication passage when the vehicle travels on a rough road. Since the roll rigidity of is reduced, the running performance on rough roads can be improved. Further, during normal traveling, the communication passage is blocked by the shut-off valve, and the roll rigidity of the vehicle is increased, so that traveling stability can be improved.
In addition, since the structure is simple, it can be implemented at low cost, which is very advantageous in terms of implementation.

According to the second aspect of the present invention, the shut-off valve is opened not only when traveling on a rough road but also when traveling straight, so that the fluid chambers of the left and right fluid dampers communicate with each other through the communication passage. As a result, the roll rigidity of the vehicle becomes low, so that the riding comfort can be improved.

Further, according to the third aspect of the present invention, even when traveling on a rough road, when the vehicle speed is equal to or higher than a predetermined speed, the shutoff valve is closed to shut off the communication passage, so that high roll rigidity ensures traveling stability. it can.

[Brief description of drawings]

FIG. 1 is a side view schematically showing an overall configuration of a vehicle suspension device according to an embodiment of the present invention.

FIG. 2 is a perspective view showing the structure of the front suspension device in a similar manner.

FIG. 3 is a front view schematically showing the structure of the front suspension device.

FIG. 4 is a flowchart showing a control flow for switching the position of the shutoff valve.

[Explanation of symbols]

 11 Control Unit (Control Means) 12 Vehicle Speed Sensor 14 Rudder Angle Sensor (Detecting Means When Driving Straight) 16 Manual Switch (Bad Road Judging Means) 22,23 Coil Spring (Mechanical Spring Means) 24, 25 Air Spring Damper (Fluid) Type damper) 24a, 25a Air chamber (fluid chamber) 31 Communication passage 32 Shut-off valve

Claims (3)

[Claims] 1. A pair of left and right mechanical spring means provided corresponding to the left and right wheels respectively, a fluid damper arranged in parallel with the spring means, and fluid chambers of the fluid dampers. A communication passage communicating with the communication passage, a shut-off valve provided in the communication passage, a bad road determination means for determining that the road surface on which the vehicle travels is a bad road, and a signal from the bad road determination means, at least A suspension device for a vehicle, comprising: a control unit that controls to open the shutoff valve when traveling on a rough road. 2. The vehicle further comprises a straight traveling time detecting means for detecting a straight traveling time of the vehicle, and the shutoff valve is capable of changing the communication resistance in at least two stages in an open state in which the communication passage is in communication. The control means receives the signal from the straight ahead detection means together with the signal from the rough road determination means, opens the shutoff valve at the time of traveling on a rough road and at the time of straight traveling, and straightens the communication resistance at the shutoff valve. The vehicle suspension device according to claim 1, wherein the suspension device is made smaller when traveling on a rough road than when traveling. 3. A vehicle speed sensor for detecting a vehicle speed is further provided, wherein the control means receives a signal from the vehicle speed sensor together with a signal from the bad road determination means, and when the vehicle speed is equal to or higher than a predetermined speed even when traveling on a bad road. The vehicle suspension device according to claim 1, wherein the shutoff valve is closed.