JP2001227578A - Damping valve of hydraulic buffer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To demonstrate the excellent damping characteristic in a favorable manner over the whole range while suppressing generation of abnormal noises by keeping the valve opening pressure to a suitable level. SOLUTION: A damping valve 2 which is a non-return valve is kept in a closed condition with a low valve-opening pressure by a coil spring 18 which is an initially-set first spring member, a leaf spring 15 which is a second spring member is added to the coil spring 18 which is the first spring member in the middle of the opening action of the damping valve 2, and the valve opening pressure is kept at the predetermined value by the coil spring 18 as the first spring member and the leaf spring 15 as the second spring member.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a damper for a hydraulic shock absorber used in parallel with a suspension device of an automobile or the like, or a strut type hydraulic shock absorber used as a suspension device itself. The present invention relates to an improvement in a damping valve of a hydraulic shock absorber which can make a damping characteristic of the hydraulic shock absorber a preferable shape.

[0002]

2. Description of the Related Art Conventionally, as a damping valve in this type of hydraulic shock absorber, an axially movable disk valve is pressed against a seat surface of a piston with a coil spring or a leaf spring while being kept closed, and the damper valve of the hydraulic shock absorber is used. When operating in a predetermined direction, the disc valve is pushed open to allow the oil to flow against the set load of the coil spring or leaf spring, and the oil flows at this time, and the damping characteristics according to the expansion and contraction speed are generated by the flow resistance of the oil at this time. It has been known.

In addition, instead of keeping the disc valve closed by the spring member as described above, the inner peripheral portion of the disc valve is fixed to the piston rod and pressed against the seat surface of the piston while giving flexure. It is also widely known that the disk valve is further deflected from this state to flow the oil so that the flow resistance of the oil at this time generates a damping characteristic according to the expansion / contraction speed.

[0004]

However, in the case of the former, the set load and the spring constant of a coil spring or a leaf spring for pressing the disk valve against the seat surface of the piston in consideration of the size of the installation space are reduced. There are limitations,
Since these set loads and spring constants cannot be set high enough, the valve opening pressure of the disc valve is relatively low, so that not only a high damping force cannot be produced, but also the disc valve suddenly opens greatly, resulting in a large pressure difference. Causes abnormal noise.

[0005] On the other hand, according to the latter, the inner peripheral portion is fixed, so that the set load and the spring constant can be freely increased from the installation space to a certain extent as compared with the former, so that high damping force can be easily achieved. On the other hand, it is not possible to produce low damping force this time, and the spring constant becomes high, making it difficult to open the disc valve. become.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a novel structure capable of exhibiting an excellent damping characteristic in a preferable form over a high and low level while suppressing the generation of abnormal noise by keeping the valve opening pressure at an appropriate level. It is an object of the present invention to provide a damping valve for such a hydraulic shock absorber.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to maintain a damping valve in a closed state at a low valve opening pressure by a first spring member which is initially set, and to set the damping valve during the opening operation of the damping valve. This is achieved by adding a second spring member to the first spring member and increasing the valve opening pressure by the first and second spring members.

Preferably, a coil spring interposed between the piston rod and the damping valve is provided as a first spring member, and the coil spring is provided as a second spring member at intervals in the valve opening direction of the damping valve. A leaf spring fixed to the rod is used.

That is, by configuring as described above,
While the hydraulic shock absorber is in an inoperative state, the damping valve is pressed against the seat surface of the piston by the first spring member that is initially set regardless of the second spring member, and the spring force of the first spring member causes The damping valve 2 is kept closed at a low valve opening pressure.

In this state, if the hydraulic shock absorber causes a relative displacement in the axial direction between the cylinder tube and the piston while pushing the damping valve open, the hydraulic shock absorber is generated while the relative displacement speed is relatively low. Since the operating oil pressure is relatively low, only the weak first spring member having a low set load and a low spring constant is bent to open the damping valve, and the damping valve operates while generating a low damping force.

Subsequently, the relative displacement speed between the cylinder tube and the piston increases, and the operating oil flowing per unit time grows. As a result, the operating oil pressure increases, and the damping valve connects the first spring member. When the second spring member comes into contact with the first spring member while being further deflected, the second spring member is also deflected in addition to the first spring member, and the damping valve is pushed open while further increasing the generated damping force. Become like

In this manner, the damping valve also bends the second spring member in addition to the first spring member during the valve opening operation, and opens the valve by the first and second spring members. By increasing the pressure, a predetermined high damping characteristic is exhibited.

Thus, the valve opening pressure at the start of opening of the damping valve is controlled by the relatively weak first spring member so as to be easily opened. By generating the characteristic, the damping valve suddenly opens greatly at the initial stage of the operation of the hydraulic shock absorber to generate an excessive pressure difference, or it is difficult to open due to the occurrence of abnormal noise, and it is preferable over a range of heights. It is possible to exhibit excellent damping characteristics in the form.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A hydraulic damper damping valve according to an embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a longitudinal sectional front view of a main part showing an example in which the present invention is applied to a damping valve 2 which is a non-return valve indirectly involved in a compression damping characteristic of a hydraulic shock absorber 1. The hydraulic shock absorber 1 includes a cylinder tube 3 and a piston rod 4 which are relatively displaced in the axial direction, as is generally well known from the past.

The piston rod 4 has a piston 7 having two rows of inner and outer expansion-side oil passages 5 and a compression-side oil passage 6 which are arranged on a concentric circle and connected by annular grooves 5a and 6a. By sliding the surface in contact with the inner wall of the cylinder tube 3, the inside of the cylinder tube 3 is partitioned into an extension-side oil chamber 8 and a compression-side oil chamber 9.

The upper surface of the piston 7 is provided with an oil hole 10 which constantly communicates the annular groove 5a of the extension-side oil passage 5 with the extension-side oil chamber 8 and covers the annular groove 6a of the compression-side oil passage 6, A non-return valve damping valve 2 which controls the opening area of the pressure side oil passage 6 of the piston 7 in accordance with the compression speed of the hydraulic shock absorber 1 and is involved in the pressure side damping characteristic is provided.

On the lower surface side of the piston 7, an annular groove 5a communicating with the extension side oil passage 5 according to the extension speed of the hydraulic shock absorber 1 is provided.
The expansion-side damping valves 11 that are involved in the expansion-side damping characteristics by controlling the opening and closing of the opening area are provided respectively.

The expansion side damping valve 11 has a valve stopper 13 disposed with a spacer 12 interposed therebetween, and the damping valve 2 which is a non-return valve at the time of pressure side operation also has a spacer 14 interposed therebetween. It has a leaf spring 15 which is a second spring member disposed, and has a valve stopper 17 disposed with a spacer 16 interposed between the leaf spring 15 and the leaf spring 15.

In this case, as shown in FIG. 2, the damping valve 2 which is a non-return valve has a large and small annular valve portion 2a and a mounting portion 2b which are arranged on one plane while maintaining a concentric state by a connecting portion 2c. By connecting and forming integrally, the mounting portion 2b is mounted by being sandwiched between the piston 7 and the spacer 14,
The valve portion 2a is arranged so that it can easily move up and down in the opening and closing direction through the connecting portion 2c.

A coil spring 18 serving as a first spring member is interposed between the damping valve 2 which is a non-return valve and a valve stopper 17 involved in the compression side damping characteristic. Into the shoulder 20
, And fastened with a piston nut 21 for mounting.

Thus, while the hydraulic shock absorber 1 is in an inoperative state, the non-return valve is set by the coil spring 18, which is the first spring member, which is initially set regardless of the leaf spring 15, which is the second spring member. Is pressed against the seat surface, which is the upper surface of the piston 7, and the damping valve 2 which is a non-return valve with a low valve opening pressure due to the spring force of the coil spring 18.
Is kept closed.

In this state, if the hydraulic shock absorber 1 causes a relative displacement in the compression direction between the cylinder tube 3 and the piston 7 while pushing and opening the damping valve 2 which is a non-return valve, Since the generated hydraulic pressure is relatively low while the displacement speed is relatively low, only the coil spring 18 which is the weaker first spring member having a lower set load and a lower spring constant is bent to provide a non-return valve. Push open damping valve 2.

As described above, the set load on the damping valve 2 which is a non-return valve is only due to the coil spring 18 which is the first spring member having a smaller load than the leaf spring 15 which is the second spring member. The hydraulic shock absorber 1 operates while generating a low damping force by the damping valve 2 which is the non-return valve.

Subsequently, the cylinder tube 3 and the piston 7
And the amount of hydraulic oil flowing per unit time increases, the hydraulic oil pressure increases, and the damping valve 2, which is a non-return valve, is further pushed open.

For this reason, the damping valve 2 comes into contact with not only the coil spring 18 as the first spring member but also the leaf spring 15 as the second spring member, which is the first spring member. Coil spring 18 and leaf spring 15 as a second spring member
Are bent in parallel.

Then, the leaf spring 15 as the second spring member
Of the first spring member, the coil spring 1
8, the load for pushing back the damping valve 2 which is a non-return valve is greatly increased.

As a result, the combined spring load of the coil spring 18 and the leaf spring 15 as the first and second spring members with respect to the opening amount of the damping valve 2 as a non-return valve suddenly increases as shown in the diagram of FIG. Accordingly, the generated damping force corresponding to the contraction speed (compression speed) of the hydraulic shock absorber 1 changes from the low damping force type to the high damping force type as shown in FIG.

In this way, the opening pressure of the damping valve 2 which is a non-return valve at the beginning of opening is controlled by the coil spring 18 which is a relatively weak first spring member so as to be easily opened. By adding a leaf spring 15 which is a second spring member to exhibit a predetermined high damping characteristic, the damping valve 2 which is a non-return valve is suddenly opened at an early stage of the operation of the hydraulic shock absorber 1. In this way, it is possible to exhibit excellent damping characteristics in a preferable form over a high and low level, while suppressing an excessive pressure difference or a state where it is difficult to open and an abnormal noise.

In the embodiment shown in FIG. 5 instead of the embodiment shown in FIG. 1 described above, the leaf spring as the second spring member is oriented in the opening direction of the damping valve 2 as a non-return valve. In contrast, in the embodiment shown in FIG. 6, the damping valve 2, which is a non-return valve, has a fixed inner circumference and is changed from an upward lift operation to a bending operation. It is a thing.

As described above, the former embodiment shown in FIG. 5 has the following advantages.
FIG. 6 shows an example in which the number of components is reduced by eliminating the coil spring 18 as the first spring member.

In each of the embodiments described above, the case where the present invention is applied to a damping valve which is a non-return valve for controlling the back pressure when the hydraulic shock absorber 1 is operated on the pressure side will be exemplified and described. As shown in FIG. 7, both the damping valve 2 and the expansion damping valve 11, which are non-return valves for controlling the compression side back pressure, or the compression side damping valve provided in a known base valve. The same is true even when a similar two-stage spring mechanism is selectively provided.

Further, one or both of the first and second spring members may be made of an elastic material such as rubber, and such a change in the structure is at least included in the scope of the present invention. Needless to say.

[0034]

As described above, according to the first aspect of the present invention, the damping valve is set to the low damping force type by the first spring member having a relatively low spring force so that the valve can be easily opened. A second spring member is also added to the above-mentioned first spring member during the opening operation of the damping valve, and the damping characteristic is switched to a predetermined high damping force type by the first and second spring members. As a result, the damping valve suddenly opens greatly at the initial stage of the operation of the hydraulic shock absorber to generate an excessive pressure difference, or a state in which the damping valve is difficult to open and abnormal noise is suppressed. Excellent damping characteristics can be exhibited.

Further, as in the second aspect of the present invention, a coil spring interposed between a piston rod and a damping valve is used as the first spring member in the first aspect of the invention, and a second spring member is provided. By using a leaf spring fixed to the piston rod at intervals in the valve opening direction of the damping valve, the invention of claim 1 can be realized with a simpler configuration.

Also, the second spring member may be formed by a plate spring that is bent in a dish shape in the opening direction of the damping valve, as in the invention of claim 3, or as in the invention of claim 4. By configuring the damping valve with a fixed inner circumference disk valve, a spacer interposed between the damping valve and the second spring member, or a coil spring as the first spring member is unnecessary, It is possible to achieve the same effect as the first aspect of the present invention while simplifying the configuration by reducing the number of parts.

Further, one or both of the first and second spring members are made of an elastic material such as rubber as in the invention of claim 5, thereby further simplifying the structure. It is possible to achieve the same effect as the invention of Item 1.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional front view of a piston portion showing a case where the present invention is applied to a damping valve which is a non-return valve related to a pressure side damping characteristic of a hydraulic shock absorber.

FIG. 2 is a plan view of a damping valve which is a non-return valve related to a pressure damping characteristic of the hydraulic shock absorber.

FIG. 3 is a diagram illustrating a relationship between an opening amount of a non-return valve and a magnitude of a spring load applied to the non-return valve according to the opening amount.

FIG. 4 is a diagram showing the relationship between the compression speed (shrinkage speed) of the hydraulic shock absorber and the magnitude of the generated damping force.

FIG. 5 is a partial vertical front view of a main part showing another embodiment of the damping valve of the hydraulic shock absorber according to the present invention.

FIG. 6 is a partial vertical front view of a main part showing still another embodiment of the damping valve of the hydraulic shock absorber according to the present invention.

FIG. 7 is a partial vertical front view of a main part showing still another embodiment of the damping valve of the hydraulic shock absorber according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Hydraulic shock absorber 2 Damping valve which is a non-return valve 2a Valve part of a damping valve 2b Mounting part 2c Connecting part 3 Cylinder tube 4 Piston rod 7 Piston 11 Extension damping valve 12, 14 Spacer 15 Plate which is a second spring member Spring 15a Plate spring warped in a dish shape 16 Spacer 17 Valve stopper 18 Coil spring as first spring member

Claims (5)

[Claims] 1. The damping valve is kept closed at a low valve opening pressure by an initially set first spring member, and the second spring member is connected to the first spring member during the valve opening operation of the damping valve. A damping valve for a hydraulic shock absorber, wherein the valve opening pressure is increased by the first and second spring members. 2. A coil spring interposed between a piston rod and a damping valve as a first spring member, and fixed to the piston rod as a second spring member at intervals in the valve opening direction of the damping valve. 2. The damping valve for a hydraulic shock absorber according to claim 1, wherein said damping valve uses a leaf spring. 3. The damping valve for a hydraulic shock absorber according to claim 2, wherein the leaf spring serving as the second spring member is formed by a plate spring which is warped in a dish shape in the valve opening direction of the damping valve. 4. The damping device according to claim 2, wherein the damping valve is held closed by fixing an inner periphery of the damping valve instead of being held closed by a coil spring serving as a first spring member. valve. 5. The damping valve for a hydraulic shock absorber according to claim 1, wherein one or both of the first and second spring members are made of an elastic material such as rubber.