JPH03262718A - Air suspension - Google Patents

Abstract

PURPOSE:To always generate optimum damping force by actuating an air cylinder by the internal pressure of an air spring suspending an axle to a car body and also varying the damping force of the shock absorber installed between the axle and the car body by the internal pressure of the air cylinder. CONSTITUTION:A wheel 10 is suspended from a frame 9 by a suspension comprising a leaf spring 11 and an air spring 12. A shock absorber 16 is installed between the leaf spring 11 and a frame bracket 17. In such device, the shock absorber 16 is provided with a lever 27 for adjusting damping force, which is connected to the piston rod 29 of an air cylinder 28. When the internal pressure of the air spring 12 is increased, for example, this internal pressure is supplied to the air cylinder 28. This pressure supplying allows the piston rod 29 to move opposing to a return spring 30 for rotating the adjusting lever 27 resulting in the improvement in the damping force of the shock absorber 16.

Description

[Detailed Description of the Invention] Field of Industrial Application] The present invention relates to an air suspension device, and in particular, an air suspension device in which an axle is suspended on a vehicle body via an air spring, and a shock absorber is interposed between the axle and the vehicle body. , relates to an F suspension device in which the vibration of an air spring is damped by this shock absorber.

(Summary of the invention) The rear axle of the truck is suspended by a suspension system that combines a leaf spring and an air spring, and a variable damping force shock absorber is installed between the rear end of the leaf spring and the frame. The internal pressure of the spring is supplied to the air cylinder through the throttle,
This air cylinder is used to switch the damping force of the shock absorber, and the damping force of the shock absorber is directly switched via the air cylinder by the internal pressure of the air spring.

K. Prior Art) As a suspension device for a truck, a leaf air combination type suspension device using a leaf spring and an air spring is used.

In this kind of suspension device, when the load increases, the leveling valve opens and air is supplied to the air spring, which increases the pressure of the air spring and increases the spring constant. .

Therefore, the suspension spring of the truck has a substantially constant resonance frequency when the truck is empty and when the truck is loaded, improving ride comfort.

In order to further improve the riding comfort of a truck having such a suspension device, it is preferable to always set the damping coefficient ratio of the shock absorber to an optimal value regardless of the load. Therefore, for example, a variable damping force type shock absorber may be used in conjunction with the suspension device, and the suspension device may be switched by an actuator.

[Problems to be Solved by the Invention] Conventionally, the live load or sprung load is detected by a leveling sensor, etc., and the detection output is supplied to a microcomputer, which controls the actuator. . The actuator switches the shock absorber according to instructions from the microcomputer, so that the shock absorber generates an optimal damping force depending on the load. Such a structure requires an electronic control device and its wiring, and also requires installation space for the electronic control W device including a computer. In addition, by adopting such a structure,
There is a drawback that the cost of the suspension HIM increases.

The present invention has been made in view of these problems, and allows the spring to have a nearly constant resonant frequency regardless of the load, without using a microcomputer, and to ensure that the shock absorber is always optimal. An object of the present invention is to provide an air suspension device that generates a damping force.

Means for Solving Problem 1 1 In the first invention, an axle is suspended on a vehicle body via an air spring, a shock absorber is interposed between the axle and the vehicle body, and the air is absorbed by the shock absorber. In a device designed to dampen the vibration of a spring,
The shock absorber is constructed of a variable damping force type, and an air cylinder operated by the internal pressure of the air spring is provided, and the damping force of the shock absorber is changed by the air cylinder.

In a second aspect of the invention, in the first aspect, a throttle means is connected between the air spring and the air cylinder.

[1] According to the first invention, the internal pressure of the air spring that changes depending on the load is supplied to the air cylinder, and this air cylinder is actuated by the internal pressure to increase the damping force of the shock absorber. This means switching to the optimum value corresponding to the live load.

Further, according to the second invention, dynamic pressure fluctuations of the air spring can be absorbed by the throttle means connected between the air spring and the air cylinder,
This prevents the shock absorber from being switched unnecessarily due to vibrations or the like during driving.

(Embodiment) FIG. 1 shows an air suspension device according to an embodiment of the present invention, in which the rear axle 10 of a truck is mounted on a frame 9 by a leaf air combination suspension device consisting of a leaf spring 11 and an air spring 12. It is designed to be suspended. A bracket 13 is fixed to the frame 9, and a pin 14 implanted in the bracket 13 is engaged with an eyepiece 15 of the leaf spring 11. Further, the rear end portion of the leaf spring 11 is connected to the lower end side of the shock absorber 16. The upper part of the shock absorber 16 is fixed to the frame 9 via a bracket 17. The air spring 12 is interposed between the leaf spring 11 and the frame 9 at an intermediate position between the axle 10 and the shock absorber 16.

Air spring 12 is connected to air tank 21 via air conduit 20. A leveling valve 22 is attached to the air pipe line 20. A detection lever 23 is provided on the leveling valve 22 so as to project rearward. The tip of this lever 23 is a link rod 24
It is connected to the axle 10 via.

Next, a mechanism for changing the damping force of the shock absorber 16 will be explained. Shock absorber 16
At the top of the is an adjustment lever 27 for adjusting the damping force.
is provided, and the tip of this adjustment lever 27 is connected to a piston rod 29 of an air cylinder 28. Note that an air spring 12 is installed inside the air cylinder 28.
Return spring 3 facing the air pressure supplied from
0 is built-in. The air cylinder 28 is connected to the air pipe 20 via a pressure regulator 31, a throttle valve 32, and a thin vibrator 33, and the air inside the air spring 12 is supplied to the air cylinder 28 through the air pipe 20. I try to do that.

In the above configuration, the rear axle 10 of the truck is buffered by the leaf springs 11 and air springs 12, and these springs 11 and 12 prevent vibrations from the road surface from being transmitted to the frame 9. ing. Further, vibrations of the springs 11 and 12 are damped by a shock absorber 16.

In addition, the air spring 12 is controlled by the leveling valve 22.
It tries to adjust the internal pressure. When a large load is applied to the truck, the detection lever 23 of the leveling valve 22 is compressed because the air spring 12 is compressed.
is rotated upward, thereby opening the leveling valve 22, compressed air in the air tank 21 is supplied to the air spring 12 through the air pipe line 20, the pressure in the air spring 12 increases, and the leveling valve 22 is opened. Spring constant increases.

On the other hand, when the live load decreases, air spring 1
Since the frame 9 is pushed up by the elastic restoring force of the air spring 12, the detection lever 23 is rotated downward, and the air inside the air spring 12 is discharged through the leveling valve 22. The constant is kept low.

Next, the operation of changing the damping force of the shock absorber 16 will be explained. The internal pressure of the air spring 12 is supplied to the air cylinder 28 via the air pipe line 20, the thin vibrator 33, the compensating valve 32, and the pressure regulator 31. When the internal pressure of the air spring 12 increases, the internal pressure of the air cylinder 28 increases. The piston provided there overcomes the return spring 30 and moves to the right, rotating the adjustment lever 27. The shock absorber 16 is provided with a throttle in its oil passage, and this throttle is made variable to adjust the damping force, and when the adjustment lever 27 is rotated as described above, the damping force increases. become.

On the other hand, when the load of the truck decreases, the internal pressure of the air spring 12 also decreases, and therefore the air pressure applied to the air cylinder 28 also decreases. Therefore, the built-in return spring 30 pushes back the piston, and as a result, the air cylinder 28 retracts the piston rod 29. Therefore, the adjustment lever 27 is rotated in the opposite direction, and the damping force of the shock absorber 16 is reduced.

Moreover, this suspension KN has an air spring of 12
A thin vibrator 33 and a compensating valve 32 are provided between the air cylinder 28 and the air cylinder 28, and by these restricting means,
The air cylinder 28 is prevented from operating due to dynamic pressure changes of the air spring 12. Therefore, as shown in FIG. 2, the air cylinder 28 does not respond to changes in the internal pressure of the air spring 12 during traveling, that is, dynamic changes, and static loads such as changes in the load of the truck. The damping force of the shock absorber 16 is changed in accordance with the pressure difference in the air spring 12 due to the change in the damping force, thereby preventing unnecessary damping force adjustment operations.

Further, a pressure regulator 31 is connected between the throttle valve 32 and the air cylinder 28, and the pressure regulator 31 changes the internal pressure of the air cylinder 28 as shown in FIG. Therefore, even if the pressure of the air cylinder 12 changes near the switching pressure, the air cylinder 28 is prevented from performing frequent switching operations, thereby eliminating unstable operation. In addition, pressure regulator 3
1 and the throttle valve 32 may be integrated. It is also possible to incorporate the air cylinder 28 into the shock absorber 16 and integrate it.

Generally, the air pressure of the air spring 12 is automatically adjusted according to the applied load, and as the load increases, the spring constant increases, making it possible to obtain a nearly constant resonance frequency when the vehicle is empty and when the vehicle is loaded. , and the ride becomes more comfortable. In order to further improve this ride comfort, it is desirable to optimize the damping coefficient ratio when the vehicle is empty and when the vehicle is loaded. The damping coefficient ratio C/Ca is expressed as: C/C - C/J mk -. In the case of an air suspension device, as the mass increases, the spring constant also increases, so when the mass increases, such as when loaded, the shock absorber 1
By increasing the damping force C of 6, the ride comfort is further improved. In particular, in the case of a truck, since the air-to-volume ratio is large, the effect is large, and the combination of the air spring 12 and the shock absorber 16 provides a truck with good riding comfort.

Moreover, conventionally a sensor, a microcomputer, and a motor have been used to switch the shock absorber 16, but in this embodiment, an air cylinder 28 that utilizes the internal pressure of the air spring 12 is used. Therefore, there is no need for electronic control parts such as sensors, microcomputers, motors, etc.
4-build construction is simple, highly reliable, and low cost. In addition, the system can be installed using only piping, and there is no need for wiring for electronic circuits or space for installing a computer.

Moreover, pressure regulator 31 and air spring 1
A throttle valve 32 is inserted between the air spring 1 and the air spring 1.
A thin vibrator 33 is connected between the air spring 1 and the throttle valve 32 to increase the resistance.
2 dynamic pressure fluctuations are absorbed. On the other hand, the throttle valve 32 and the pressure regulator 31 are connected by a thick vibrator to increase the volume and reduce the pulsating pressure. Therefore, the effect of reducing pulsating pressure is further enhanced, and the switching operation of the shock absorber 16 becomes stable.

Effects of the Invention 1 As described above, the first invention consists of a shock absorber of a variable damping force type, and also includes an air cylinder operated by the internal pressure of an air spring, and the air cylinder acts as a shock absorber. The damping force is changed. Therefore, air spring 12
It is now possible to directly utilize the internal pressure of the shock absorber to change the damping force of the shock absorber via the air cylinder, thereby providing a suspension system that always provides good ride comfort regardless of changes in the live load.

According to the second invention, in which a throttle means is connected between the air spring and the air cylinder, dynamic pressure changes of the air spring can be absorbed by the throttle means, and the shock absorber It becomes possible to prevent unnecessary switching.

[Brief explanation of drawings]

FIG. 1 is a piping diagram showing the configuration of an air suspension device according to an embodiment of the present invention, FIG. 2 is a graph showing the operation of the throttle, and FIG. 3 is a graph showing the operation of the pressure regulator. The names of the main parts in the drawings are as follows. 9 ・ 10 ・ 11 ・ 12 ・ 16 ・ 21 ・ 22 ・ 27 ・ 28 ・Frame・Axle・Leaf spring・Air spring・Shock absorber・Air tank・Leveling valve・Adjustment lever・Air cylinder 31...Pressure regulator 32・... Throttle valve 33... Thin pipe

Claims (1)

[Claims] 1. The axle is suspended on the vehicle body via an air spring, and a shock absorber is interposed between the axle and the vehicle body, and the vibration of the air spring is damped by the shock absorber. In the device, the shock absorber is configured with a variable damping force type, and an air cylinder operated by the internal pressure of the air spring is provided, and the damping force of the shock absorber is changed by the air cylinder. Features an air suspension device. 2. The air suspension device according to claim 1, wherein a throttle means is connected between the air spring and the air cylinder.