JPH02278026A - Hydraulic shock absorber - Google Patents

Abstract

PURPOSE:To enhance the freedom of setting damping force by forming a back pressure chamber on the outside surface of a disc valve used for generating damping force, and communicating the back pressure chamber with a pressure chamber between the disc valve and a piston through a passage. CONSTITUTION:Disc valves 42, 37, 33 constitute a damping force generating mechanism 45 on an extension side together with an annulus ring-shaped oil chamber 32 of a piston 23, a passage 36 and a back pressure chamber 40, etc. The damping force generating mechanism 46 on a contraction side is installed between the piston 23 and a step part 22A of a piston rod 22. Valves 37, 51 are opened after opening the disc valves 32, 42, 47 to increase the pressure inside the back pressure chambers 40, 54. The freedom of setting damping force is thus enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a hydraulic shock absorber suitably used to dampen vertical vibrations applied to a vehicle, for example, and in particular,
The present invention relates to a hydraulic shock absorber that can obtain damping force characteristics with a high degree of freedom.

[Prior Art] FIGS. 7 and 8 show hydraulic shock absorbers according to the prior art.

In the figure, 1 is a cylinder, 2 is a piston rod that is provided to protrude into the cylinder 1, and 3 is a piston that is fixed to the piston rod 2 and slides along the inner wall of the cylinder 1. Then, piston 3 causes cylinder 1
There are two oil chambers A inside.

A damping force is generated in the oil flowing from one oil chamber to the other oil chamber when the piston 3 moves to the extension side or the contraction side, thereby providing a vibration damping effect. It is configured as follows.

Next, the above-mentioned damping force generation mechanism will be explained.

4.5 is a valve seat formed in an annular shape near the outer periphery of both ends of the piston 3, 6.7 is a protrusion provided on the inner periphery of both ends of the piston 3, and the valve seats 4 and 5 are the protrusions 6 and 7. It is in a slightly more prominent state. Further, 8.9 is fitted to the piston rod 2, and its inner peripheral edge is provided with protrusions 6 and 7, respectively.
The disk valves 10.11 on the contracting side and the extending side are in contact with the disk valves 8.9 and whose outer peripheral edges are seated on and off the valve seat 4.5, respectively, and 10.11 is a disk valve 8.9 in the direction in which each of the disk valves 8.9 is moved off the valve seat 4.5. 12.1 Spacer that enables deformation of
3 indicates a regulating member (retainer) that regulates the degree of opening of each disc valve 8.9, and the disc valve 8, spacer 10, and regulating member 12 are connected to the piston 3 and the piston rod 2.
The disc valve 9, the spacer 11, and the regulating member 13 are also sandwiched between the piston 3 and a lock nut 14 screwed onto the piston rod 2. Of the disk valves 8.9, the reduction side disk valve 8 is made up of two overlapping disks, and the expansion side disk valve 9 is made up of three overlapping disks. And disc valve 8.9
define annular oil chambers 15, 16 between the disc valve 8.9 and each end face of the piston 3 by abutting against the protrusions 6, 7 and the valve seat 4.5, respectively. Reference numerals 17 and 18 denote communication passages on the extension side and contraction side provided in the piston 3, respectively. The communication passage 17 on the extension side communicates between the oil chamber A and the annular oil chamber 16, and the communication passage 18 on the contraction side is for communicating the oil chamber B and the annular oil chamber 15, and each communication passage 1
7.18 is provided at an angle with respect to the axis of the piston 3. Furthermore, the innermost disk 9A of the disk valve 9 has a plurality of notches 19, 19. ... is formed.

The hydraulic shock absorber according to the prior art has the above-mentioned configuration, and its operation will now be explained with reference to FIG. 8.

Suppose now that the piston 3 is displaced together with the piston rod 2 in the direction of arrow X (extension side) in FIG. As a result, the pressure inside the oil chamber A becomes high, and a pressure difference is generated between the oil chamber A and the oil chamber B. For this reason, the oil in the oil chamber A is transferred from the communication passage 17 to the annular oil chamber 1.
6 and flows into the oil chamber B via a notch 19 provided in the disc valve 9. Since the flow path area of the notch 19 is narrowed to form an orifice, a predetermined damping force is generated as shown by the characteristic line ρ in FIG. 8 when passing through the northern part. When the piston 3 is displaced at high speed, the pressure within the oil chamber A increases, and this pressure is guided into the annular oil chamber 16 and acts on the disc valve 9 on the extension side. and,
When the pressure acting on the disc valve 9 reaches the level of the damping force F and becomes greater than the spring force (valve opening pressure) of the disc valve 9, its outer peripheral edge portion deforms and separates from the valve seat 5. As a result, the flow path area from the annular oil chamber 16 to the oil chamber B increases, and the damping force characteristic has a two-stage characteristic that changes as shown by the characteristic line ρ2.

On the other hand, when the piston 3 is displaced in the direction of arrow X (reduction side) contrary to the above, the same operation as described above is performed. however,
Since the disk valve 9 on the expansion side uses three disks, and the disk valve 8 on the contraction side uses two disks,
The opening pressure of the disc valve 9 is higher than that of the disc valve 8, so that the extension stroke in which the piston 3 is displaced in the X direction exhibits higher damping force characteristics than the contraction stroke in which the piston 3 is displaced in the X direction. .

[Problem to be Solved by the Invention J] By the way, in the above-mentioned prior art, the characteristic line β1. shown in FIG. Although the damping force characteristics change depending on the speed of the piston 3, such as ρ2, this characteristic is different from the disc valve 8.
．． Since it is determined by the preset valve opening pressure of 9,
For example, when trying to obtain a low damping force in a relatively low speed region of 0.1 to 0.3 m/s, there is a problem that it is not possible to generate a high damping force in a high speed region of about 0.6 m/s, for example. . Also, as shown in the characteristic line shown by the dotted line in Figure 8, if you try to obtain a high damping force at a high speed of about 0.6 m/s, conversely, if you try to obtain a high damping force at a high speed of about 0.1 to 0.3 m/s, There is a problem that the damping force becomes too high in the range.

The present invention was made in view of the problems of the prior art described above, and the present invention can obtain multi-stage damping force characteristics with a high degree of freedom in setting. For example, a low damping force is generated in a low piston speed range. The present invention provides a hydraulic shock absorber that can generate high damping force in high-speed ranges.

[Means for Solving the Problems] A feature of the configuration adopted by the present invention in order to solve the above-mentioned problems is that at least one of the damping force generation mechanisms on the extension side and the contraction side is connected to the end surface of the piston. a disc valve that generates a damping force by seating on and off a valve seat formed in the valve seat; A pressure chamber that applies valve pressure, a back pressure chamber located on the outer surface of the disc valve that applies back pressure to the disc valve, and a pressure chamber that is connected to the back pressure chamber through the inner circumference of the disc valve. A passage is provided between the back pressure chamber and the pressure chamber to communicate with each other, and the passage is closed with a valve opening pressure greater than that of the disc valve, and when the valve is opened, the pressure in the pressure chamber is reduced to the back pressure. and a valve for introducing the gas into the chamber through the passage.

[Operation J] With the above configuration, as the speed of the piston sliding in the cylinder increases and the pressure in the pressure chamber increases, the disc valve first opens, and then the valve opens to reduce the pressure in the pressure chamber. It can be introduced into the back pressure chamber through a passage, thereby increasing the pressure in the back pressure chamber, causing this pressure to act on the disc valve as back pressure, and adjusting the valve opening of the disc valve according to the back pressure. The opening can be adjusted to a higher degree, making it possible to generate high damping force.

〔Example〕

Embodiments of the present invention will be described below with reference to FIGS. 1 to 6.

In the figure, 21 is a cylinder, and 22 is one end of the cylinder 21.
The figure shows a piston rod that is inserted into the cylinder 21 and protrudes from the other end to the outside of the cylinder 21. A small diameter portion 22B is provided at one end of the piston rod 22 via a stepped portion 22A, and the outer periphery of the tip side of the small diameter portion 22B is A male thread 22C is formed in the. Reference numeral 23 indicates a piston fixed to the small diameter portion 22B of the piston rod 22 via a lock nut 24, etc., and the piston 23 defines the inside of the cylinder 21 into oil chambers A and H, almost the same as the piston 3 described in the prior art. and valve seat 25,2
6. The valve seat 2 located on the right side in FIG.
6 has a second notch 26A, 26A serving as an orifice.
The notches 26A are formed as shown in the figure, and each notch 26A has the same function as each notch 19 described in the prior art.

Further, the protrusions 27 and 28 of the piston 23 are provided with radial oil grooves 27A and 27 that communicate with annular oil chambers 31 and 32, which will be described later.
A, 28A, 28A are formed on the inner peripheral side of the piston 23, and each oil groove 27A.

Annular oil grooves 27B and 28B communicating with 28A are formed. Reference numerals 31 and 32 indicate annular oil chambers as pressure chambers located between the valve seats 25 and 26 and the protrusions 27 and 28 on both end sides of the piston 23;
2 is an end face of the piston 23 and a disc valve 47, which will be described later.
33, and is always in communication with the oil chambers B and A via communication passages 30.29.

Reference numeral 33 indicates a first disc valve on the extension side that is provided on one end side of the piston 23 so as to be seated on and off the valve seat 26, and the disc valve 33 has a plurality of disc valves, similar to the disc valve 9 described in the prior art. Although it is formed by overlapping two disks, there is a third disk on the inner circumference side.
As shown in the figure, for example, three oil grooves 33A, 33A,...
・is formed in an arc shape. An annular oil chamber 3 is provided on the inner side (left side in FIG. 1) of the disc valve 33.
The pressure inside the valve 2 acts as a valve opening pressure, and the pressure inside a back pressure chamber 4o, which will be described later, acts on the outer surface thereof as a back pressure.

34 is fitted into the small diameter portion 22B of the piston rod 22,
The holding member 34 is shown holding the disc valve 33 between it and the protrusion 28 of the piston 23, and the holding member 34 is formed into a stepped cylindrical shape with a large diameter portion 34A on the negative side in the axial direction (the right side in the figure). A valve seat 34B for a disk valve 37, which will be described later, is formed in an annular shape on the outer circumferential side of the large diameter portion 34A, and a protrusion 34C for sandwiching the disk valve 37 between it and a spacer 35 is formed on the inner circumferential side thereof. has been done. Moreover, the holding member 3
As shown in FIG. 4, for example, three oil grooves 34D, 34D, . Oil grooves 34E, 34E, . . . whose insides communicate with each oil groove 34D.
is formed in the radial direction. And each oil groove 34D,
34E constitutes a passage 36 that communicates between the annular oil chamber 32 and the back pressure chamber 40 together with the oil grooves 28A, 28B, and 33A.

Reference numeral 37 indicates a second disc valve as a valve that is seated on and off the valve seat 34B of the holding member 34. The disc valve 37 is formed to have a smaller diameter than the disc valve 33, and has a larger opening pressure than the disc valve 33. The passage 36 is normally closed. When the disc valve 37 is opened, the annular oil chamber 32 and the back pressure chamber 40 are connected to each other.
The pressure inside the annular oil chamber 32 is introduced into the back pressure chamber 40 by communicating with the inside through the passage 3G.

Reference numeral 38 indicates a bottomed cylindrical guide member fitted into the small diameter portion 22B of the piston rod 22, and a guide cylinder 38A extending in the axial direction toward the piston 23 is formed on the outer peripheral side of the guide member 38. A movable piston 39, which will be described later, is slidably inserted into the guide cylinder 38A. Further, a disc valve 42 (described later) is provided on the bottom side of the guide member 38.
The valve seat 38B and the protrusion 38C are formed in an annular shape,
Cuff holes 38D, 38D, . . . , which constantly communicate with the inside of the back pressure chamber 40, are bored at predetermined intervals in the circumferential direction in the radially inner portion of the valve seat 38B.

Reference numeral 39 indicates a movable piston located between the guide member 38 and the disc valve 33 and slidably inserted into the guide cylinder 38A. , surrounding the disc valve 37. The movable piston 39 defines a back pressure chamber 40 with the guide member 38, and the back pressure chamber 40
The internal pressure acts as a back pressure on the outer surface of the disc valve 33 at the radially inner portion via a small diameter portion 39A formed on the lid side of the movable piston 39. Also,
The cylindrical portion 39B of the movable piston 39 has a plurality of small holes 39C.
are drilled in the radial direction, and each of the small holes 39C allows the oil chamber B and the back pressure chamber 40 to communicate with each other at all times, so that when the piston 23 is stopped, the back pressure chamber 4o and the oil chamber B are returned to the same pressure. During sliding, a sudden increase in pressure within the back pressure chamber 40 is alleviated.

Reference numeral 41 indicates a spring that biases the movable piston 39 toward the disc valve 33 side with a weak spring load;
1 is located in the back pressure chamber 40, inserted through the small diameter portion 22B of the piston rod 22, and is held between the spacer 35 and the guide member 38. The spring 41 has three protrusions 41A that protrude in the radial direction as shown in FIG.
.

41A, . . . are formed, and each of the protruding portions 41A is bent slightly in advance toward the movable piston 39 to apply a small biasing force to the movable piston 39.

42 is a spacer 43. between the protrusion 38C of the guide member 38 and the nut 24. The third
The disc valve 42 is seated on and off the valve seat 38B of the guide member 38, and is set to have a larger opening pressure than the disc valve 37. The disc valve 42 has a back pressure chamber 4.
0 pressure acts through each sleeve hole 38D, and the back pressure chamber 40
The pressure within is the damping force F illustrated in FIG.

When the pressure rises to this level, the disc valve 42 opens to communicate the back pressure chamber 40 and the oil chamber B. Here, the disc valves 42, 37, 33, together with the annular oil chamber 32 of the piston 23, the passage 36, the back pressure chamber 40, etc., constitute a damping force generating mechanism 45 on the extension side.

Next, reference numeral 46 indicates a damping force generation mechanism on the reduction side provided between the piston 23 and the stepped portion 22A of the piston rod 22. disc valve 47, holding member 48, spacer 49, passage 50, second disc valve 51 as a check valve, guide member 52, movable piston 53, back pressure chamber 54, spring 55, third disc valve 56
, a spacer 57, a retainer 58, etc., and these are formed almost similarly to each member of the damping force generating mechanism 45 on the extension side. Oil grooves 47A are formed on the inner peripheral side of the disc valve 47, and the holding member 48 has a large diameter portion 48A and a valve seat 48, similar to the holding member 34.
B, a protrusion 4.8C, and oil grooves 48D and 48E are formed, and the passage 50 is the oil groove 27A, 27B, and 47A.

48D and 48E. The guide member 52 also includes a guide cylinder 52 similar to the guide member 38.
A, a valve seat 52B, a protrusion 52C, and each sleeve hole 52D are provided, and the movable piston 53 is provided with the movable piston 39.
Similarly, the small diameter portion 53A, the cylindrical portion 53B, and each small hole 53C.
The spring 55 is formed with three protrusions 55A, 55A, . . . as shown in FIG.

The hydraulic shock absorber according to this embodiment has the above-mentioned configuration, and for its operation, the piston rod 22 is
An example of displacement in the direction of arrow X (extension side) in the figure will be described with reference to FIG. 6.

First, the piston 23 and the piston rod 22 are
When the piston 23 is displaced in the direction, the inside of the oil chamber A becomes high pressure, so this pressure oil flows through the communication passages 29 of the piston 23 to the annular oil chamber 3.
2 and flows out to the oil chamber B side through each notch 26A serving as an orifice, the characteristic line C1 in FIG.
When the speed of the piston 23 increases and the pressure in the oil chamber 32 reaches the level of the damping force F, the disc valve 33 opens and the characteristic line C2
A damping force along the direction is generated. Also, at this time, the pressure inside the oil chamber 32 is equal to the oil grooves 28A and 28B.

The second
continues to act on the disc valve 37.

Then, the speed of the piston 23 further increases and the oil chamber 32
When the pressure inside the passage 36 reaches the level of the damping force F2, the disc valve 37 opens and the oil chamber 32 and the back pressure chamber 40 are opened.
The pressure inside the back pressure chamber 40 is the same as the pressure inside the oil chamber 32. This acts as back pressure on the radially inner portion of the disc valve 33, and this back pressure acts in a direction that restricts the opening degree of the disc valve 33, thereby changing the damping force characteristic along the characteristic line I2s in FIG. The slope of the slope suddenly becomes higher. moreover,
The speed of the piston 23 increases and the pressure is increased from the oil chamber 32 to the back pressure chamber 40.
When the pressure in the back pressure chamber 40 reaches the level of the damping force F, the third disc valve 42, which is acted upon by the pressure in the back pressure chamber 40 through the sleeve holes 3 and 8D, opens, so that the characteristic line 12
A damping force along 4 is generated.

Further, when the piston rod 22 is displaced together with the piston 23 in the direction of arrow Y (reduction side) in FIG.
The inside becomes high pressure, and this pressure oil is introduced into the annular oil chamber 31 through the communication path 30, and is introduced into the oil grooves 27A, 27B, 47A.
, 48D, and 48E on the second disc valve 51, first, when the pressure in the oil chamber 31 reaches the level of the damping force f, the first disc valve 47 opens; When the pressure in the oil chamber 31 and the passage 50 reaches the level of due to the damping force, the disc valve 51 opens and the pressure in the back pressure chamber 54 increases, and further, the pressure in the oil chamber 31 increases.
When the pressure in the back pressure chamber 54 reaches the level of the damping force f, the third disc valve 56 opens and four stages of damping force characteristics can be obtained as shown in FIG.

In this embodiment, the damping force generating mechanism 45.4 on the extension side and the reduction side is activated during the extension stroke and contraction stroke of the piston rod 22.
The first disc valves 33, 47, second disc valves 37.51, and third disc valves 42.56 that make up For example, when the speed of the piston 23° is 0.1 to 0.3 m/s, a relatively low damping force can be generated in a low speed range of about 0.6rn/s, and a high damping force can be generated in a high speed range of about 0.6rn/s. It has various effects such as being able to generate damping force and greatly improving the degree of freedom in setting the damping force.

In the above embodiment, the notch 26A as an orifice is formed in the valve seat 26 of the piston 23, but instead of this, for example, the disc valve 9 described in the prior art may be formed in the disc valve 33 on the extension side. Notch 1
A notch similar to 9 may be formed.

Further, in the above embodiment, the small holes 39G, 53C are formed in the cylindrical portions 39B, 53B of the movable piston 39.53, but instead of this, the guide members 38.52
A notch similar to the notch 26A may be formed in the valve seats 38B, 52B of the third disk valve (or a notch similar to the notch 19 may be formed in the third disc valve 42.56). .

Further, in the above embodiment, the damping force generating mechanisms 45 and 46 on the extension side and the contraction side are provided at both ends in the axial direction of the piston 23, but the present invention is not limited to this. .46 may be adopted, and the other damping force generating mechanism may be constructed in the same manner as that of the prior art. Further, a damping force generating mechanism 45, 46 equivalent to the damping force generating mechanism 45, 46 may be provided on the bottom side of the cylinder 21.

Further, in the above embodiment, the third disc valve 42.56 is used to obtain four stages of damping force characteristics, but these disc valves 42,56 may be abolished to provide three stages of characteristics. In this case, it is not necessary to form each oil filler 38D, 52D in the guide member 38.52.

Furthermore, in the embodiment, the passage 36.50 communicating between the annular oil chamber 32.31 and the back pressure chamber 40.54 is
The disc valve 37.51 is configured to be closed at all times, but instead of the disc valve 37.51, a check valve such as a ball valve body or the like is provided in the middle of the passage 36.50. This check valve may be set to have a greater opening pressure than the first disc valve 33, 47.

Further, in the embodiment, the first disc valve 33.4
between the movable piston 39.7 and the guide member 38.52.
53 to define the back pressure chamber 40.54, but instead of the movable piston 39.53, a cylinder made of an elastic material, for example, is installed on the outer surface side of the disc valve 33.47 at the radially inner portion. The cylindrical body may be slidably inserted into the guide member 38.52, in which case the guide member 38.52 may be formed with a small diameter to correspond to the cylindrical body. There are advantages such as being able to eliminate the springs 41.55.

〔Effect of the invention〕

As detailed above, according to the present invention, a back pressure chamber is formed on the outer (rear) side of the disc valve for generating damping force, and this back pressure chamber is connected to the pressure chamber between the disc valve and the piston via a passage. Since the passage is configured to be closed by a valve having a higher opening pressure than the disc valve, by opening this valve after opening the disc valve and increasing the pressure in the back pressure chamber, The valve opening of the disc valve can be adjusted according to the back pressure from the back pressure chamber, and low damping force can be generated in the low speed range of the piston and high damping force in the high speed range, improving the degree of freedom in setting the damping force. I can do it.

[Brief explanation of drawings]

1 to 6 show embodiments of the present invention, FIG. 1 is a longitudinal sectional view of a hydraulic shock absorber, FIG. 2 is a right side view of FIG. 1 showing a piston, and FIG. 3 is a disc valve. A side view showing the
Fig. 4 is a side view of the holding member, Fig. 5 is a side view of the spring, Fig. 6 is a damping force characteristic diagram, Figs. 7 and 8 show the prior art, and Fig. 7 is a hydraulic shock absorber. The longitudinal sectional view and FIG. 8 are damping force characteristic diagrams. 21...Cylinder, 22...Piston rod, 23
... Piston, 25.26 ... Valve seat, 27゜2
8... Projection, 29.30... Communication path, 31.32.
...Annular oil chamber (pressure chamber) 33, 42, 47° 56
... Disc valve, 34.53 ... Holding member, 3
6.50... Passage, 37.51... Disc valve (valve), 38.52... Guide member, 39.53...
・Movable piston, 40.54... Back pressure chamber, 41°55
... Spring, 45.46 ... Damping force generation mechanism.

Claims (1)

[Claims] a cylinder; a piston that is slidably inserted into the cylinder and defines two oil chambers; In a hydraulic shock absorber comprising a damping force generation mechanism on an extension side and a contraction side that generate damping force, at least one of the damping force generation mechanisms is attached to a valve seat formed on an end surface of the piston. A disc valve that is seated and separated to generate a damping force, and a pressure that is located inside the valve seat and is formed between the disc valve and the end surface of the piston and that applies valve opening pressure to the inner surface of the disc valve. a back pressure chamber located on the outer surface side of the disc valve to apply back pressure to the disc valve, and communicating the back pressure chamber and the pressure chamber via the inner peripheral side of the disc valve, A passage provided between the back pressure chamber and the pressure chamber, and closing the passage with a valve opening pressure greater than that of the disc valve, and transmitting the pressure of the pressure chamber to the back pressure chamber through the passage when the valve is opened. A hydraulic shock absorber comprising a valve for introducing the hydraulic shock absorber.