JPH0534167B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a vehicle suspension system which is of a gas spring type and whose spring constant can be varied.

[Technical background of the invention and its problems]

2. Description of the Related Art A vehicle suspension system is known in which a cylinder contains gas and oil to provide a spring function using the gas and a damping function using the oil. A suspension system of this type in which the spring constant can be changed was developed by the present inventors, and patent application filed in 1982-
It has already been filed as No. 42889. This thing is
An auxiliary tank is provided separately from the cylinder, the gas chamber of the cylinder and the gas chamber of the auxiliary tank are connected by a gas pipe, and an on-off switching valve is provided in the middle of the gas pipe, and this on-off switching valve is controlled. In particular, the gas volume functioning as a gas spring is changed to change the spring constant.

However, in this case, a separate auxiliary tank is required, making the entire device bulky. Additionally, it requires gas piping that is difficult to seal, which is disadvantageous in terms of gas leakage prevention. In addition, there were other problems that needed to be resolved, such as the use of long gas pipes increased flow path loss, making it difficult for short-cycle vibrations to be transmitted to the auxiliary tank, and making it difficult to ride in response to high-frequency vibrations.

[Object of the Invention] The present invention has been made based on the above-mentioned circumstances, and its purpose is to miniaturize the device and facilitate sealing measures in a vehicle suspension device capable of changing the spring constant. Furthermore, the object is to obtain a vehicle suspension system that is effective against high-frequency vibrations.

[Summary of the invention]

The gist of the present invention is to provide a suspension system for a vehicle comprising a cylinder and a rod having a piston part and an orifice part housed inside the cylinder, in which the cylinder has a double layer consisting of an outer cylinder and an inner cylinder. The structure is such that the inner cylinder is provided with an inner gas chamber filled with compressed gas serving as a gas spring that urges the rod in a direction to push the rod out of the cylinder, and an inner oil chamber filled with oil. The piston portion is disposed in the inner oil chamber, and an outer gas chamber is formed between the outer cylinder and the inner cylinder in which compressed gas is filled as a gas spring that biases the rod in a direction to push the rod out of the cylinder. However, the outer gas chamber and the inner gas chamber are connected by a gas passage, and an opening/closing switching mechanism is provided for opening and closing the gas passage.

According to the suspension system having the above structure, when the inner gas chamber and the outer gas chamber are in communication with each other, the gas volumes of both act as a gas spring, so that the spring constant is reduced and flexible cushioning properties are obtained. Furthermore, when the gas passage is shut off, only the inner gas chamber functions as a gas spring, making it possible to increase the spring constant.

In addition, in the present invention, one cylinder has the above two
Since two types of gas chambers are provided, it is possible to integrate the two gas chambers that function as gas springs, the gas passage, and the opening/closing switching mechanism into a unit, eliminating the need for separate auxiliary tanks and gas piping. This is very advantageous in terms of compactness of the device and sealing measures. Therefore, costs are also reduced. Furthermore, the inner gas chamber and the outer gas chamber are located close to each other, eliminating the need for long gas piping. Therefore, there is little flow path loss, and the outer gas chamber can easily follow high-frequency vibrations in the inner gas chamber, leading to improved riding comfort.

[Embodiments of the invention]

A first embodiment of the present invention will be described below with reference to FIG. In the figure, 1 is a cylinder, into which a rod 4 having a piston part 2 and an orifice part 3 is inserted. This rod 4 projects from the underside of the cylinder 1.
Further, a mounting part 5 is provided at the lower end of the rod 4 for mounting to the axle, and a mounting part 6 is provided at the upper end of the cylinder 1 for mounting to the vehicle body.
It is now used as a so-called inverted suspension system.

Further, the rod 4 is hollow, and oil is housed inside to improve heat dissipation.
Further, a motor is housed inside the rod 4 as an example of a drive mechanism 7 for driving an orifice movable member 14, which will be described later, and is controlled to be driven by an external motor controller 9 through wiring 8. There is. Further, a substantially cylindrical bumper rubber 10 is mounted upward on a support plate 11 so as to cover the lower side of the rod 4.

The orifice section 3 includes a well-known plate valve type orifice 13 provided on the piston section 2, and a rotary movable member 1 that can change the cross-sectional area of the flow path.
It consists of a variable orifice 15 with 4. The movable member 14 is rotationally driven by the drive mechanism 7 so as to change the cross-sectional area of the flow path, and the damping force can be arbitrarily switched. 16
17 is a dry bearing, and 17 is a rebound stopper lever.

On the other hand, the cylinder 1 has a double structure consisting of an outer cylinder 20 and an inner cylinder 21. An inner gas chamber 22 for storing high-pressure nitrogen gas is formed at the upper part of the inner cylinder 21, and an inner oil chamber 23 is formed at the lower side of the inner gas chamber 22. This inner oil chamber 23
The piston portion 2 is disposed therein.

Furthermore, an outer gas chamber 25 is formed between the outer cylinder 20 and the inner cylinder 21. An inner oil chamber 27 is provided below the gas chamber 25 via a free piston 26 having a sealing function. A hydraulic unit 29 is connected to an oil port 28 communicating with the outer oil chamber 27, so that oil can be taken in and out of the outer oil chamber 27. 30 is a hydraulic power source, and 31 is an oil tank.

Further, a gas passage 36 communicating with the inner gas chamber 22 and the outer gas chamber 25 is formed in the upper wall 35 of the cylinder 1.
An opening/closing switching mechanism 37 for opening and closing 6 is provided. The opening/closing switching mechanism 37 includes, for example, a plunger-shaped solenoid 38, a valve body 39 provided on the plunger of the solenoid, a return spring 40, and the like.

A dry bearing 42 and a hydraulic seal 43 are provided on the lower wall 41 of the cylinder 1 at a portion that comes into sliding contact with the rod 4. Furthermore, a second bumper rubber 44 is provided to protrude downward so as to surround the upper outer side of the bumper rubber 10.

The first embodiment of the device having the above configuration has the following effects: the rod 4 expands and contracts relative to the cylinder 1;
It can perform spring function and damping function. That is, when the rod 4 moves in the direction of contraction, the piston part 2 moves upward in the inner oil chamber 23 while passing oil through the orifice 13, thereby generating a damping force and compressing the gas in the inner gas chamber 22. The pressure increases, and the repulsive force of the rod 4 increases. On the other hand, when the rod 4 moves in the extending direction, the inner gas chamber 22 expands, contrary to the above, and a damping force is generated by the movement of the piston portion 2.

In the above configuration, when the valve body 39 is open and the inner gas chamber 22 and the outer gas chamber 25 are in communication, both gas chambers 22 and 25 function as gas springs, so the spring constant decreases, resulting in a flexible suspension. As a result, a good ride comfort can be obtained.

Furthermore, when the valve body 39 is switched to block the gas passage 36, only the inner gas chamber 22 functions as a gas spring, so the spring constant increases. Therefore, it is useful for stabilizing the vehicle body posture when driving around a curve, suddenly starting, or stopping suddenly. In other words, it is preferable to open and close the gas passage 36 depending on the driving situation of the vehicle or the road surface condition. This switching may be performed manually, but it is also possible to use sensors to detect driving conditions, road surface conditions, etc., and to actually switch the opening and closing of the gas passage 36.

On the other hand, using the hydraulic unit 29, the outer oil chamber 27
By putting oil in and taking out the oil, the internal pressure or volume of the gas chambers 25, 25 changes as the oil amount changes, and as a result, the elongation of the rod 4 can be adjusted. In other words, it is possible to adjust the vehicle height. Furthermore, the damping force can also be adjusted by operating the drive mechanism 7 to change the rotational position of the movable member 14 of the orifice and by changing the cross-sectional area of the flow path.

According to the suspension system having the above configuration, the gas chambers 22 and 25 are provided in a double cylindrical shape in one cylinder, and the outer gas chamber 25 is provided with a function as an auxiliary tank, so the auxiliary tank is installed separately. It can be configured more compactly than the . Further, the gas passage 36 only needs to be formed in a part of the cylinder 1, and no gas piping is required, which is extremely advantageous in terms of gas sealing. In addition, the gas passage 36 is short,
Since the flow path loss is small, high-frequency vibrations can be easily followed, which improves riding comfort.

Next, a second embodiment of the present invention will be described with reference to FIG. It should be noted that since the basic structure, operation, and effects are the same as those of the first embodiment, the same reference numerals are given to the common parts and the explanation thereof will be omitted.

In this second embodiment, a free piston 50 having a sealing function to partition the inner gas chamber 22 and the inner oil chamber 23 is provided inside the inner cylinder 21, and the inner oil chamber 23 is connected to the inner oil chamber 23 through the oil passage 51. A hydraulic unit 29 is connected thereto, so that oil can be injected into both the inner oil chamber 23 and the outer oil chamber 27. Note that a check valve 52 is provided in the oil passage 51.

Furthermore, a rod 4 is attached to the lower wall 41 of the cylinder 1.
A first seal 53 and a second seal 5 are placed in the sliding contact area with the
4,55 are provided. The first seal 53 is located on the inner oil chamber 23 side, and is designed to allow a slight flow of oil.
A drain pipe 57 is connected via a drain passage 56 between the first seal 53 and the second seal 54. This drain pipe 57 is connected to the on-off valve 6
0 to the tank 61.

In the second embodiment having the above configuration, oil from the hydraulic unit 29 can flow into both the inner oil chamber 23 and the outer oil chamber 27, and the vehicle height can be adjusted. In addition,
The oil that has flowed into the inner oil chamber 23 can be collected into the tank 61 via the drain pipe 57 by switching the on-off valve 60.

FIG. 3 shows a third embodiment of the present invention, in which only a gas chamber 25 is provided between the outer cylinder 20 and the inner cylinder 21, but other points are the same as the second embodiment. It is. That is, the hydraulic unit 29 is
It is configured so that oil can be taken in and out only to the inner oil chamber 23 via the oil passage 51. Also in the third embodiment, the vehicle height can be adjusted, the damping force can be adjusted, and the spring constant can be changed in the same manner as in the first and second embodiments.

4 to 6 show a fourth embodiment of the present invention. In this device, a rod-shaped movable member 70 is used to change the flow path cross-sectional area of the orifice.
This embodiment is different from the first embodiment in that the movable member 70 is rotated by a drive mechanism 71 provided at the upper part of the cylinder 1. More specifically, as illustrated in FIG. 6, the movable member 70 has a flow portion 72 cut off on one side, and is rotatably inserted into a guide tube 73. In addition, the guide tube 73 has a hole 7.
4 is provided, and this hole 74 and the above-mentioned circulation part 7
The cross-sectional area of the flow path is maximized when the two directly face each other. Although a rotary solenoid is suitable for the drive mechanism 71, other known drive means may be employed. In this example,
The vertical movement of the valve body 39 is also guided by the guide tube 73.

Furthermore, FIGS. 7 to 9 show a fifth embodiment of the present invention. In this embodiment, the lower side of the cylinder 1 and the rod 4 are housed in a support tube 81 equipped with an axle pin 80, and the outer circumferential surface of the cylinder 1 is oriented in the axial and periaxial directions with respect to the support tube 81. It is slidable. 82, 83
84 indicates a dry bearing, and 84 indicates a bellows-shaped dust cover. Further, the lower end of the rod 4 is supported via a bumper lever 85 so as to be movable vertically and laterally. Reference numeral 86 is a member for preventing slippage.

Furthermore, in this fifth embodiment, a tubular movable member 9 is used to change the flow passage cross-sectional area of the orifice.
0 is adopted, and this movable member 90 is rotated by a drive mechanism 71 at the top of the cylinder. More specifically, as illustrated in FIG. 9, the movable member 90 has a flow portion 91 cut off on one side, and is rotatably inserted into the guide tube 73. And the guide tube 73 has a hole 7.
4 is provided, and this hole 74 and the above-mentioned circulation part 9
The cross-sectional area of the flow path is maximized when the two are directly facing each other.

Further, an oil passage 92 is formed in the center of the movable member 90 in the axial direction thereof, so that oil from the hydraulic unit 29 can be taken in and out of the inner oil chamber 23 via a rotary joint 93. .

According to the fifth embodiment with the above configuration, the cylinder 1 is rotatable and telescopic with respect to the support tube 81, so that it is not necessary to not only extend and contract but also rotate, as in the case of a front suspension strut of an automobile, for example. Valid in certain cases. Moreover, the first
As in the fourth embodiment, it is of course possible to change the spring constant, adjust the vehicle height, and adjust the damping force.

FIG. 10 shows a sixth embodiment of the invention.
In this embodiment, the movable member 14 for changing the flow passage cross-sectional area of the orifice is rotated by a drive mechanism 7 such as a motor housed in the rod 4, as in the first embodiment. There is. Furthermore, in this sixth embodiment, a drain pipe 100 and an oil feed pipe 101 are inserted into the gap between the outer cylinder 20 and the inner cylinder 21, that is, the outer gas chamber 25. This drain pipe 100 is connected to a drain passage 56 having a structure similar to that described in the second embodiment (see FIG. 2), and drain can be recovered via an on-off valve 60. One end of the oil pipe 101 is connected to an inner oil chamber 23, and the other end is connected to a hydraulic unit 29, so that oil can be taken in and out of the inner oil chamber 23 and the vehicle height can be adjusted. It's summery.

[Effects of the Invention] As described above, according to the present invention, in a gas-filled suspension system that can change the spring constant, two types of gas chambers that function as gas springs are built into one cylinder. These gas chambers, gas passages, opening/closing switching mechanisms, etc. can be integrated into a unit, eliminating the need for separate auxiliary tanks and gas piping.
This has the effect of making the device more compact and making gas sealing easier.

In addition, the inner gas chamber and outer gas chamber are located close to each other, eliminating the need for long gas piping.
Flow path loss is low, and the outer gas chamber can easily follow high-frequency vibrations in the inner gas chamber.
The ride comfort is good when the spring constant is lowered.

[Brief explanation of drawings]

1 to 4 are sectional views showing the first to fourth embodiments of the present invention, respectively, FIG. 5 is an enlarged view of the orifice portion in FIG. 4, and FIG. 6 is a - line in FIG. 5. FIG. FIG. 7 is a sectional view showing the fifth embodiment of the present invention, FIG. 8 is an enlarged view of the orifice portion in FIG. 7, and FIG. 9 is a -
FIG. 10 is a sectional view taken along a line showing a sixth embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Cylinder, 2... Piston part, 3... Orifice part, 4... Rod, 20... Outer cylinder, 21... Inner cylinder, 2
2...Inner gas chamber, 23...Inner oil chamber, 25...Outer gas chamber, 27...Outer oil chamber, 36...Gas passage, 37...
Open/close switching mechanism.

Claims (1)

[Claims] 1. A vehicle suspension system comprising a cylinder and a rod having a piston part and an orifice part installed inside the cylinder, wherein the cylinder has a double structure consisting of an outer cylinder and an inner cylinder. and an inner gas chamber filled with compressed gas serving as a gas spring that urges the rod in a direction to push the rod out of the cylinder, and an inner oil chamber filled with oil are provided inside the inner cylinder, and In addition to arranging the piston portion in the oil chamber, an outer gas chamber is also provided between the outer cylinder and the inner cylinder in which compressed gas is filled as a gas spring that biases the rod in a direction to push the rod out of the cylinder, A suspension system for a vehicle, characterized in that the inner gas chamber and the outer gas chamber are connected by a gas passage, and an opening/closing switching mechanism is provided for opening and closing the gas passage. 2. An outer oil chamber partitioned from the outer gas chamber by a free piston is provided between the outer cylinder and the inner cylinder, and a hydraulic unit is connected to the outer oil chamber for taking oil in and out. A vehicle suspension system according to scope 1. 3. The system according to claim 1 or 2, wherein a free piston is provided inside the inner cylinder to partition the inner gas chamber and the inner oil chamber, and a hydraulic unit is connected to the inner oil chamber. Vehicle suspension system. 4. Claims characterized in that the orifice section is configured with a movable member that can change the cross-sectional area of the flow path, and the movable member is controlled by a drive mechanism provided on the cylinder or rod. The vehicle suspension system described in any one of Items 1 to 3. 5 A first seal and a second seal are provided at the sliding portion of the cylinder with respect to the rod, spaced apart from each other in the axial direction, and the first seal located on the inner oil chamber side allows oil to flow slightly. The vehicle suspension system according to any one of claims 1 to 4, wherein a drain pipe is connected between the first seal and the second seal. 6. The lower side of the cylinder and the rod are housed in a support cylinder equipped with an axle pin, and the outer peripheral surface of the cylinder is slidable with respect to the support cylinder, and the center part of the cylinder is arranged in the axial direction. The vehicle suspension system according to any one of claims 1 to 5, characterized in that oil is taken in and out of the inner oil chamber through an oil feed pipe that passes through it. 7. The lower side of the cylinder and the rod are housed in a support cylinder equipped with an axle pin, and the outer circumferential surface of the cylinder is slidable with respect to the support cylinder, and there is a gap between the inner cylinder and the outer cylinder. The drain pipe is inserted between the inner cylinder and the outer cylinder to lead to the outside of the cylinder, and the oil pipe of the hydraulic unit is also inserted between the inner cylinder and the outer cylinder, and this oil pipe is connected to the inner oil chamber. A vehicle suspension system according to claim 5, characterized in that: