JPH03153936A - Fluid pressure type suspension - Google Patents

Abstract

PURPOSE:To carry out accurate centering in installation of both cylinders by forming the inner end surface of a bottom member to be welded and fixed to the blocked end of the outer cylinder in the spherical concave state and by forming the outer end surface of an inner bottom member to be fitted to the blocked end surface of the inner cylinder in the spherical convex state with the same radius of curvature. CONSTITUTION:The inner end surface of an outer bottom member 10 to be fixed to the blocked end surface of an outer cylinder 3 is made in the spherical concave state with the radius of curvature of R. An inner bottom member 15 to be liquid-tightly fitted to the blocked end surface of an inner cylinder 4 inserted and arranged concentrically on the inside of the outer cylinder 3 through a sealant 18 for the bottom is formed in the spherical convex state with the same radius of curvature R as the radius of curvature R of the outer bottom member 10. After insertion, when a seal housing 61 is attached on the opening end of the outer cylinder 3 and the inner cylinder is pressed, centering is automatically carried out as both the bottoms are in the spherical state.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a hydraulic suspension device used in a suspension system of a vehicle such as an automobile.

[Prior Art] A hydraulic suspension device includes a housing having a liquid chamber therein, a rod inserted into the housing, and the like. An example of a housing is an oil housing that has a double wall structure (twin tube) consisting of an outer cylinder and an inner cylinder, and uses the sealed space between the outer cylinder and the inner cylinder as a liquid chamber or an air chamber. Dampers or hydropneumatic suspensions are also known.

In the case of a double-walled housing consisting of an outer cylinder and an inner cylinder, the outer circumference of the piston portion provided on the rod is in slidable contact with the inner surface of the inner cylinder.

Further, the longitudinally intermediate portion of the rod is slidably supported in the axial direction by a rod guide bushing provided near the open end of the housing. Therefore, if the centers of the outer cylinder and inner cylinder or wood guide bushings are misaligned with each other, or if the housing and rod are not parallel, the rod will not be able to slide smoothly, which will deteriorate the quality of the suspension system. Become. Therefore, the outer cylinder, inner cylinder, guide bushing, etc. must be assembled with high precision.

Conventional double-walled housings are known, for example, from Japanese Patent Application Laid-open No. 1986-
As seen in Japanese Patent No. 67410, a structure is adopted in which an end member provided at the closed end of the inner cylinder is butted against an end surface of an end member provided at the closed end of the outer cylinder.

[Problems to be Solved by the Invention] In the case of a conventional double-walled housing, the end member provided at the closed end of the inner cylinder is welded to the inner cylinder. Even if a steel pipe is used, a portion of the inner cylinder will become brittle due to the heat during welding. Therefore, the strength of the inner cylinder must be set based on the vicinity of the welded portion where the strength is reduced, and the inner cylinder becomes thicker.

Furthermore, accuracy is also important in assembling the guide bushing provided on the open end side of the housing. That is, as mentioned above, the rod is supported by the guide bushing so that it can move freely in the axial direction, so if the center of the guide bushing deviates even slightly from the center of the inner cylinder, the parallelism of the rod to the inner cylinder will be affected. This will damage the rod and prevent it from sliding smoothly.

Therefore, an object of the present invention is to be able to easily regulate the parallelism of the rod with respect to the inner cylinder with high precision;
Moreover, it is an object of the present invention to provide a fluid pressure suspension system that does not cause problems even if the axes of the outer cylinder and the inner cylinder are slightly inclined relative to each other.

[Means for Solving the Problems] The present invention developed to achieve the above object includes an outer cylinder and an outer bottom member fixed to the closed end side of the outer cylinder and having a spherical concave support seat on the inner end surface. a straight inner cylinder disposed concentrically inside the outer cylinder; and a support seat for the outer bottom member that is fluid-tightly fitted to the closed end side of the inner cylinder via a bottom sealing material. an inner bottom member having a spherical convex end surface in contact with the inner bottom member, a rod inserted into the inner cylinder from the open end side of the inner cylinder, and a rod that is fluid-tightly fitted to the open end of the inner cylinder via a sealing material. a rod guide bushing held by the bushing housing and whose inner circumferential surface is in sliding contact with the outer circumferential surface of the rod, and a rod guide bushing which is inserted into the open end of the outer cylinder and of the inner bottom member. and a seal housing that presses the inner cylinder in a direction that presses the spherical convex end surface against the support seat of the outer bottom member.

[Function] When assembling the inner cylinder inside the outer cylinder, the suspension system of the present invention can be assembled by inserting the inner cylinder inside the outer cylinder and inserting the seal housing into the open end of the outer cylinder. Press the cylinder in the axial direction. By doing so, the spherical convex end surface of the inner bottom member is pressed against and comes into contact with the spherical concave support seat of the outer bottom member, thereby automatically centering the inner cylinder with respect to the outer cylinder. Further, a bushing housing is fitted near the open end of the inner cylinder, and the rod guide bushing is held by this bushing housing.
Since the axially intermediate portion of the rod is slidably supported by the rod guide bushing, the parallelism between the rod and the inner cylinder can be accurately regulated.

Since the closed end of the outer cylinder and the closed end of the inner cylinder are in contact with each other at the spherical support seat, even if the axis of the outer cylinder and the axis of the inner cylinder are similar to each other to some extent, the inclination of both axes will be the same as the above-mentioned spherical surface. absorbed by the shaped parts.

[Example 1] An example of the present invention will be described below with reference to FIGS. 1 to 3.

A double-walled housing 2 employed in the illustrated hydraulic suspension system 1 includes an outer cylinder 3 and a straight inner cylinder 4 disposed concentrically inside the outer cylinder 3. .

The inner cylinder 4 made of a steel pipe has its strength increased by, for example, drawing, and has a mirror-finished inner surface. Then, the rod 6 is inserted into the inner cylinder 4 from the open end 5 side located at the upper side of the inner cylinder 4 in the figure.

An outer bottom member 10 is fixed to the closed end (lower end side in the drawing) of the outer cylinder 3 by welding. Welding part 1
1 extends around the entire circumference of the outer bottom member 10. A spherical concave support seat 12 with a radius of curvature R is formed on the inner end surface of the outer bottom member 10.

On the other hand, an inner bottom member 15 is provided on the closed end side of the inner cylinder 4. This inner bottom member 15 is
As shown in FIG. 3, etc., there is a short cylindrical body 16 that is inserted into the end of the inner cylinder 4, an annular groove 17 formed in the body 16 over the entire circumferential direction, and a It is configured to include a bottom sealing material 18 such as an O-ring attached to a groove 17, a flange portion 19 having a larger outer diameter than the body portion 16, and the like. And the inner bottom member 15 is
It has a spherical convex end surface 20. The radius of curvature of this end face 20 matches the radius of curvature R of the support seat 12 described above. This inch bottom member 15 is fluid-tightly fitted and maintained at the end of the inner cylinder 4 without welding by inserting the body 16 into the inner cylinder 4 until the flange 19 abuts the end surface of the inner cylinder 4. be done.

The inside of the inner cylinder 4 is partitioned into a first liquid chamber 25 on the upper side in the figure and a second liquid chamber 26 on the lower side in the figure, with a valve base 33 below as a boundary. These liquid chambers 25 and 26 accommodate oil as an example of hydraulic fluid.

A connecting member 27 having a mount insulator is provided at the upper end of the rod 6, and the upper end of the rod 6 is fixed to a member on the vehicle body side via this connecting member 27. A bracket 28 is provided at the bottom of the outer cylinder 3 for connection to an axle side member.

A stud 30 is fixed to the lower end of the rod 6 located inside the inner cylinder 4. This stud 30 is provided with a rebound stopper 31, a damping force generating mechanism 32, and the like. A slide bearing 3 is attached to a piston-shaped valve base 33 that constitutes a part of the damping force generation mechanism 32.
4 is provided. The valve base 33 is fixed to the stud 30 by a nut 35.

At the center of the rod 6, there is an in-rod communication hole 40 along the axial direction.
is provided. A rotary valve 4 is provided between this communication hole 40 and a stud communication hole 41 provided in the stud 30.
A variable orifice mechanism 43 using 2 is provided.

The variable orifice mechanism 43 is configured such that by rotating the rotary valve 42 to an appropriate position, an orifice flow passage cross-sectional area can be obtained depending on the rotational position. That is, depending on the rotational position of the rotary valve 42, the first liquid chamber 25
and the second liquid chamber 26 and the in-rod communication hole 4
0 and the stud flow hole 41 can be changed. The rotary valve 42 is rotated by a predetermined angle by an actuator 45 such as a stepping motor via a control shaft 44 passing through the in-rod communication hole 40 .

A shaft seal assembly 50 is provided on the open end 5 side (upper end side in the drawing) of the outer cylinder 3 and the inner cylinder 4.

The configuration of the shaft seal assembly 50 will be described below.

A bushing housing 52 is fluid-tightly inserted into the open end 5 of the inner cylinder 4 via a sealing material 51 such as an O-ring. A rod guide bushing 53 is provided inside the bushing housing 52, and the inner circumferential surface of the rod guide bushing 53 is in slidable contact with the outer circumferential surface of the rod 6.

An intermediate sleeve 55 is provided on the outer end side of the bushing housing 52, and a high pressure sealing device 56 is provided between the intermediate sleeve 55 and the bushing housing 52.

A sealing material 57 such as an O-ring is also provided between the intermediate sleeve 55 and the bushing housing 52.

A low pressure seal device 60 using an oil seal or the like is provided inside the seal housing 61.

A male thread 62 is provided on the outer periphery of the seal housing 61. By screwing the male thread 62 into a female thread 63 provided on the inner surface of the outer cylinder 3, the seal housing 61 is fixed to the outer cylinder 3, and the seal housing 61 is fixed to the outer cylinder 3. As 61 is screwed in, the end face of the inner cylinder 4 is pushed in the axial direction and an axial force is generated.

That is, in this shaft seal assembly 50, by screwing the seal housing 61, the end face of the intermediate sleeve 55 is pushed in the axial direction, and by the intermediate sleeve 55 pushing the end face of the bush housing 52 in the axial direction, the inner cylinder 4 The structure is such that the spherical end surface 20 of the inner bottom member 15 is pressed against the spherical support seat 12 of the outer bottom member 10.

Therefore, according to this shaft seal assembly 50, not only is the centering of the inner cylinder 4 with respect to the outer cylinder 3 automatically performed, but also the axis of the inner cylinder 4 may be misaligned with the outer cylinder 3 due to processing errors or dimensional tolerances of various parts. Even if the assembly is somewhat inclined with respect to the axis of the outer bottom member 10 and the inner bottom member 15, the spherical fitting between the outer bottom member 10 and the inner bottom member 15 can absorb such an inclination of the axis.

Further, the bushing housing 52 can be fitted into the mirror-finished inner cylinder 4 with high accuracy, and the axially intermediate portion of the rod 6 is supported by the rod guide bushing 53 held by the bushing housing 52. At the same time, since the mirror-finished inner cylinder 4 has a two-point support structure in which the slide bearing 34 located at the end of the rod 6 is slidably supported by the inner surface of the inner cylinder 4, the rod 6 is parallel to the inner cylinder 4. degree can be regulated accurately. In this way, the rod 6 supported by the inner cylinder 4 can slide smoothly in the axial direction of the inner cylinder 4 with respect to the outer cylinder 3, regardless of the mold.

Between the seal housing 61 and the intermediate sleeve 55 there is a small gap 70 communicating between the high pressure sealing device 56 and the low pressure sealing device 60. In addition, the bush housing 5
A plurality of small holes 71 communicating with the gap 70 are provided in the circumferential direction near the outer periphery of 2. These small holes 71 and gaps 70 guide leak liquid leaked from the high-pressure sealing device 56 to the drain storage section 72 . The drain storage section 72 is
This utilizes the sealed space between the outer cylinder 3 and the inner cylinder 4. Further, a drain discharge lower 3 is provided at an axially intermediate portion of the outer cylinder 3. The drain discharge lower 3 is normally blocked by a plug 74, but if necessary, by removing the plug 74,
The liquid and pressure accumulated in the drain storage section 72 can be discharged.

A first chamber 81 and a second chamber 82 are attached to a bracket 80 provided near the upper end of the rod 6. The first chamber 81 includes a retractable partition member 84 using a metal bellows inside a chamber body 83. A liquid chamber 85 defined by the inner surface of the partition member 84 communicates with the in-rod communication hole 40 via a flow path 86 provided in the bracket 80 .

An air chamber 87 defined between the outer surface of the partition member 84 and the inner surface of the chamber body 83 is filled with high-pressure inert gas such as nitrogen. The pressure of the high-pressure gas in the air chamber 87 acts in a direction to contract the partition member 84, and also acts on the hydraulic fluid in the liquid chamber 25, 26 via the in-rod communication hole 40. Therefore, the pressure of the gas acts in a direction to push the rod 6 out of the housing 2. The gas is sealed at a pressure sufficient to support the sprung load of the suspension system 1. The gas pressure depends on the sprung load, but is, for example, around 50 to 80 kg f/am 2 in neutral conditions.

The second chamber 82 also includes a retractable partition member 91 using a metal bellows inside the chamber body 90. A liquid chamber 92 defined by the inner surface of the partition member 91 communicates with the in-rod communication hole 40 via an on-off valve 93 and a flow path 94 provided in the bracket 80 . The opening and closing of the on-off valve 93 is controlled by an actuator 95 such as a solenoid. An air chamber 96 defined between the outer surface of the partition member 91 and the inner surface of the chamber body 90 is filled with high-pressure gas similar to the air chamber 87. A bump stopper 97 and a dust cover 98 are attached to the lower surface side of the bracket 80.

The bump stopper 97 is connected to the rod 6 against the housing 2.
Specifies the contraction side stroke end of .

Next, the operation of the suspension system 1 having the above configuration will be explained.

When the rod 6 moves from the neutral state to the direction in which it is pushed into the inner cylinder 4 (retraction side), a part of the working fluid in the second fluid chamber 26 passes through the damping force generation mechanism 32 and is transferred to the first fluid chamber 25 side. At the same time, a portion of the hydraulic fluid in the inner cylinder 4 passes through the rotary valve 42 and the in-rod communication hole 40 and flows into the first chamber 81 according to the increase in the amount of pushing of the rod 6 into the inner cylinder 4 . The liquid flows into the liquid chamber 85 and further compresses the air chamber 87. At this time, the on-off valve 93 of the second chamber 82
If the valve is opened, the liquid chamber 92 of the second chamber 82
Oil also flows into the air chamber 96 and compresses the air chamber 96. That is, when the on-off valve 93 is in the open state, the two air chambers 8
Since 7 and 96 work together as a gas spring, the spring constant can be lowered. If the on-off valve 93 is closed, only the air chamber 87 of the first chamber 81 acts as a gas spring.
Spring constant increases.

Contrary to the above, when the rod 6 moves in the direction of withdrawal from the inner cylinder 4 (extension side), a part of the hydraulic fluid in the first fluid chamber 25 passes through the damping force generation mechanism 32 and flows into the second fluid. room 2
At the same time, the hydraulic fluid in the first chamber 81 flows into the inner cylinder 4 through the in-rod communication hole 40 and the rotary valve 42 in accordance with the decrease in the pushing amount of the rod 6 relative to the inner cylinder 4. , air chamber 87
capacity increases. At this time, if the on-off valve 93 of the second chamber 82 is opened, the oil in the second chamber 82 will also flow into the inner cylinder 4, so the two air chambers 87 and 96 will act as gas springs. They work together to provide a low bounce constant.

The hydraulic pressure in the inner cylinder 4 is always maintained by the sealing device 56.6.
Acts on 0. In the high-pressure sealing device 56, there is a possibility that a portion of the working fluid leaks little by little when the rod 6 moves to the extension side, but the leaked fluid is blocked by the low-pressure sealing device 60, and the gap 70 and small hole 71
It can be made to flow into the drain storage part 72 through.

In the above embodiment, the seal housing 61 is attached to the outer cylinder 3 by screwing, but instead, as shown in FIG. 4, the seal housing 61 is pressed in the axial direction using a jig 99. However, it may also be fixed to the outer cylinder 3 by seam welding.

〔Effect of the invention〕

According to the present invention, the assembly of the inner cylinder to the outer cylinder can be carried out smoothly and with high precision.
The parallelism of the inner cylinder and rod can also be regulated with high precision. Moreover, since there is no need to weld the inner cylinder, various problems associated with welding, such as a decrease in the strength of the inner cylinder and welding distortion, can be avoided.

[Brief explanation of the drawing]

1 to 3 show one embodiment of the present invention, FIG. 1 is a longitudinal sectional view showing a part of the suspension system, and FIG. 2 is a longitudinal sectional view showing the entire suspension system shown in FIG. 1. 3 is a perspective view showing the cylinder and the bottom member, and FIG. 4 is a sectional view showing a modification of the shaft seal assembly. 1... Fluid pressure suspension system, 3... Outer cylinder,
4... Inner cylinder, 5... Open end, 6... Rod, 10... Outer bottom member, 12... Spherical concave support seat, 15... Inner bottom member, 18... Bottom seal Material, 20... Spherical convex end surface, 34...
・Slide bearing, 50... Shaft seal assembly, 5
DESCRIPTION OF SYMBOLS 1... Seal material for housing, 52... Bushing housing, 53... Rod guide bushing, 55...
・Intermediate sleeve, 56...High pressure sealing device, 60...
・Low pressure seal device, 61...Seal housing, 72
...Drain storage section.

Claims (1)

[Claims] an outer cylinder, an outer bottom member fixed to a closed end side of the outer cylinder and having a spherical concave support seat on an inner end surface, a straight inner cylinder disposed concentrically inside the outer cylinder; an inner bottom member that is liquid-tightly fitted to the closed end side of the inner cylinder via a bottom sealing material and has a spherical convex end surface that comes into contact with the support seat of the outer bottom member; and an open end side of the inner cylinder. a rod that is inserted into the inner cylinder from above; a bushing housing that is fluid-tightly fitted to the open end of the inner cylinder via a sealing material; a rod guide bush that slides into contact with the outer cylinder; and a seal housing that is inserted into the open end of the outer cylinder and presses the inner cylinder in a direction that presses the spherical convex end surface of the inner bottom member against the support seat of the outer bottom member. A fluid pressure suspension system comprising: