JPH0320594Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a hydraulic shock absorber which is attached to a vehicle such as an automobile and is suitable for use in damping both expansion and contraction vibrations.

[Prior Art] Conventionally, this type of hydraulic shock absorber includes a piston that is slidably provided within a cylinder and defines two oil chambers within the cylinder, and a piston that is provided on both sides of the piston in the axial direction. disk valves on the extension side and contraction side are formed in the piston to communicate the two oil chambers, and openings on one side of each other are respectively closed by the disk valves,
In order to give the oil fluid flowing through the expansion side and contraction side communication passages whose openings on the other side open into the oil chamber, and one of the communication passages, an expansion and contraction rising characteristic, a fixed orifice formed in one of the disc valves or the piston and located on the side of the opening of the communication passage closed by one of the disc valves; A structure in which the area is smaller than the effective cross-sectional area of the communication path is known.

In a hydraulic shock absorber configured in this way, a predetermined damping force is generated in a low speed region by the pore resistance force of the oil flowing through a fixed orifice, and in a high speed region, the disc valve opens and a predetermined damping force is generated. It is possible to generate a damping force of 1,000,000,000,000,000,000,000,000,000,000,000,000, and provide a two-stage damping force characteristic.Moreover, the high-speed damping force characteristic in the reduction stroke is lowered in view of the ride comfort of the vehicle.

[Problem that the invention attempts to solve]

However, in the conventional technology described above, the gradient after opening the valve is determined primarily in both the extension stroke and the contraction stroke. On the other hand, if you want to keep the medium speed range low, the high speed range will only have the characteristic of extending the slope. In particular, during the reduction stroke, you want to set the medium speed range low to improve ride comfort, and the high speed range high due to vehicle strength.
It is impossible to achieve both. As a result, the number of disc valves on the extension side is greater than the number of disc valves on the contraction side, and the damping force characteristics in the extension stroke are higher.In addition, the low-speed damping force characteristics due to the fixed orifice are If you set a high characteristic that matches the high-speed damping force characteristic, the low-speed damping force characteristic will become too high on the reduction side.
The disadvantage is that low high-speed damping force characteristics cannot be obtained. Conversely, if the damping force at low speeds due to the fixed orifice is set to a low characteristic to match the high-speed damping force characteristics on the contraction side, the high-speed damping force characteristics on the extension side will become too low, resulting in poor handling stability and vehicle body. This will cause strength problems.

The present invention was devised in view of the problems of the prior art described above, and provides a degree of freedom in setting the damping force characteristics, especially on the reduction side. The object of the present invention is to provide a hydraulic shock absorber that can obtain a high damping force in the subsequent high speed range.

[Means for solving problems]

In order to solve the above problems, the feature of the configuration adopted by the present invention is that when the hydraulic pressure in the oil chamber reaches a predetermined value or more, at least one of the disc valves has a valve connected to the other disc valve in the communication passage. A valve body that closes the side opening is provided facing the opening, and a valve body is provided between the valve body and the other side opening of one communication passage even after the communication passage is closed by the valve body. Another fixed orifice is provided to allow oil to flow through the communication path.

[Effect]

With this configuration, when the piston is displaced to either the extension side or the contraction side, the first stage low-speed damping force is applied by the oil flowing through one fixed orifice when the piston speed is slow. Then, when the piston speed increases a little and the pressure in the oil chamber increases, the oil flowing in from the opening on the other side of the first communication passage opens the disc valve on the opposite side, and the relatively flat second disc valve opens. A medium-speed damping force is generated in the first stage, and then as the piston speed increases, a third stage damping force is generated that rises transiently until the valve body closes the opening on the other side of one communicating passage, and then After the piston speed increases and the valve body completely closes the opening on the other side, a high-speed damping force with high damping force can be obtained by the fixed orifice.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

1 to 3 show a first embodiment of a hydraulic shock absorber according to the present invention.

In the figure, 1 is a cylinder, 2 is a piston rod protruding into the cylinder 1, and 3 is a piston fixed to the piston rod 2 and sliding along the inner wall of the cylinder 1. and,
There are two oil chambers A in the cylinder 1 due to the piston 3,
A damping force is generated in the oil flowing from one oil chamber to the other oil chamber when the piston 3 is displaced as an extension stroke or a contraction stroke, thereby producing a vibration damping effect. is configured to do so.

Next, 5 and 6 are annular protrusions formed on the inner periphery of the inner end surface of the piston 3, 7 and 8 are valve seats formed on the outer periphery of the outer end surface of the piston 3, and 9 is located on the oil chamber B side. Another valve seat formed on the outermost circumference of the piston 3 is shown, and the valve seat 9 has a slightly smaller protrusion length in the axial direction than the valve seat 8.

Reference numerals 10 and 11 indicate disc valves located on both sides of the piston 3 and fitted into the piston rod 2. The inner peripheral edges of the disc valves 10 and 11 are in contact with the protrusions 5 and 6, and the outer peripheral edges are in contact with the valve seat 7. , 8, and there are protrusions 5, 6 between both end surfaces of the piston 3 and the disc valves 10, 11.
and the annular oil chambers 12 and 13 by the valve seats 7 and 8.
is formed. Here, one disc valve 10 is made by stacking three disc valves, and the other disc valve 11 is made by stacking four small-diameter disc valves 11A and one large-diameter disc valve 11B. diameter disc valve 1
The spring force of 1B is slight and is intended to prevent the check valve body 23, which will be described later, from coming off.

14 and 15 are spacers for holding each disc valve 10 and 11 between the protrusions 5 and 6; 16 and 1;
Reference numeral 7 indicates a regulating member that regulates the opening degree of each disc valve 10, 11, and the disc valve 10, spacer 14, and regulating member 16 are held between one end surface of the piston 3 and the stepped portion 2A of the piston rod 2,
Further, the disc valve 11, the spacer 15, the regulating member 17, and the other end surface of the piston 3 are held between a nut 18 screwed onto the tip of the piston rod 2.

Reference numerals 19 and 20 denote communication passages that are inclined and bored along the axial direction of the piston 3. One communication passage 19 communicates the annular oil chamber 12 with the oil chamber B, and the other communication passage 20 communicates the oil chamber B with the annular oil chamber 12. The chamber A and the annular oil chamber 13 are communicated with each other. The oil chamber B side opening 19A of one of the communication passages 19 opens into an annular oil chamber 21 formed between the valve seats 8 and 9.

Further, 22 is a notch formed on the outer peripheral side of the disc valve on the side facing the piston 3 of one disc valve 10, and permanently communicating between the oil chamber A and the annular oil chamber 12. The effective cross-sectional area of the notch 22 is formed to be smaller than the effective cross-sectional area of the communication path 19. Then, the notch 22
constitutes a fixed orifice that sets the low-speed damping force characteristics in both the extension stroke and the contraction stroke.

Next, 23 is an annular check valve body, and the inner peripheral edge of the check valve body 23 is connected to the other disc valve 1.
The small-diameter disc valve 1 is fitted onto the outer circumferential surface of the small-diameter disk valve 1 with a very small gap, and the outer circumferential edge facing the piston 3 is seated on and off the valve seat 9. The thickness of the check valve body 23 is the same as that of the small diameter disc valve 11A, and a small annular gap Δt is formed between the check valve body 23 and the valve seat 9. Further, the back side of the check valve body 23 is held by the aforementioned large-diameter disk valve 11B and is prevented from coming off, and when the oil chamber B side reaches a predetermined pressure corresponding to the medium speed region, the large-diameter The disk valve 11B is bent so that the check valve body 23 is seated on the valve seat 9.

Furthermore, 24 is another notch formed in the valve seat 9, and 24 constantly communicates the oil chamber B and the annular oil chamber 21 even after the check valve body 23 is seated on the valve seat 9. It is something to do. and,
The effective cross-sectional area of the notch 23 is the same as that of the notch 2 described above.
The fixed orifice is formed to have a larger effective cross-sectional area than the communication passage 20 and smaller than the effective cross-sectional area of the communication passage 20, and constitutes another fixed orifice that sets the high-speed damping force characteristic in the reduction stroke.

The present embodiment is constructed as described above, and its operation will now be described.

First, assume that the piston 3 is displaced together with the piston rod 2 in the extension direction (direction of arrow X in FIG. 1). As a result, the pressure inside the oil chamber A becomes high, and the pressure inside the oil chamber B becomes high.
A differential pressure occurs between the Therefore, the oil in the oil chamber A flows into the annular oil chamber 12 from the notch 22, flows into the annular oil chamber 21 from the communication passage 19, and further flows out into the oil chamber B. Since the effective cross-sectional area of the cutout 22 is smaller than that of the communication path 19, a predetermined damping force is generated when the cutout 22 passes through this portion. This is the third
Obtain the low-speed damping force characteristics on the extension side, shown as OA _X in the figure.

When the piston 3 is displaced at high speed, the pressure within the oil chamber A increases, and this pressure is led to the annular oil chamber 13 via the communication path 20 and acts on the disc valve 11. When this pressure becomes greater than the spring force of the disc valve 11, the disc valve 11 is separated from the valve seat 8, and due to the resistance force when the oil fluid flows through the communication passage _{20 ,} Obtain the high-speed damping force characteristics on the extension side as shown. Therefore, in the extension stroke, two stages of damping force characteristics are obtained as in the prior art.

Next, a case will be described in which the piston 3 is displaced in the contraction direction (direction of arrow Y in FIG. 1) opposite to that described above.

In this case, the pressure in the oil chamber B becomes high, and therefore the oil in the oil chamber B flows from the annular oil chamber 21 to the communication path 1.
9, annular oil chamber 12, oil chamber A via notch 22
leaks into At this time, a low-speed damping force characteristic on the reduction side shown as _Y in FIG. 3 is obtained. Note that this characteristic _Y is the same as the characteristic _X on the extension side.

Then, as the speed of the piston 3 increases, the pressure in the oil chamber B increases, and when this pressure becomes greater than the spring force of the disc valve 10, the disc valve 10 is separated from the valve seat 7, as shown in FIG. Inside _{Y Y}
The medium-speed damping force characteristic on the reduction side is obtained as shown as . If the point on the extension line of _{Y Y} is ′ _Y , then _{Y Y} ′ _Y
represents the high-speed damping force characteristic on the reduction side according to the prior art.

When the speed of the piston 3 gradually increases in the above state, the pressure in the oil chamber B further increases, and the pressure acting on the check valve body 23 causes it to gradually bend toward the valve seat 9, resulting in a predetermined pressure. When this point is reached, the check valve body 23 finally seats on the valve seat 9, resulting in the state shown in FIG. During this time, the minute distance shown as Δt in FIG. 1 gradually narrows, the effective cross-sectional area decreases, and the damping force increases. The characteristics during this period are the third
With the transient characteristics shown as B _{Y CY} in the diagram, the notch 24
From the time when the effective cross-sectional area due to Δt becomes smaller than the effective cross-sectional area of the communication passage 19 until the check valve body 23 is seated on the valve seat 9, there is a rapid change.

Furthermore, since the damping force characteristic after the check valve body 23 is seated on the valve seat 9 depends only on the effective cross-sectional area of the notch 24, _the damping force characteristic _YY due to the notch 24 shown in FIG. , high-speed damping force characteristics _{Y Y} can be obtained.

In this way, during the contraction stroke, multi-stage characteristics _{Y Y Y Y} can be obtained as shown in Figure 3, so even if the damping force characteristic _Y at low speed is set to the same characteristic as the expansion side, the multi-stage It is possible to suppress a low damping force in the mid-speed range that affects comfort, and generate a high damping force _{Y Y} in the high-speed range as well as on the extension side.
Stability of maneuvering can be ensured.

Next, FIG. 4 shows a second embodiment of the present invention,
FIGS. 5 and 6 show a third embodiment of the present invention, and in each of these embodiments, the same components as in the first embodiment are given the same reference numerals and their explanations will be omitted.

First, the features of the second embodiment shown in FIG.
They all have the same protruding length in the axial direction, and instead of this, another small-diameter disk valve 31 having a slightly larger diameter than the small-diameter disk valve 11A is provided on the side facing the piston 3 of the disk valve 11, and the small-diameter disk valve 31 The minute distance Δt is set according to the thickness of the plate. Furthermore, in this embodiment, a notch 32 is provided in the valve seat 7 instead of the disc valve 10.

This embodiment is configured as described above, but since there is no change in its operation, a detailed description will be omitted.
In this embodiment, the minute distance Δt can be arbitrarily adjusted by adjusting the plate thickness of the small-diameter disc valve 31.

Next, the feature of the third embodiment shown in FIGS. 5 and 6 is that the protrusion 6' formed on the piston 3 and the valve seats 8' and 9' are the same as in the second embodiment. with a protruding length, and a small diameter disc valve 31 instead.
and instead of providing a notch 22 in the valve seat 9', a notch 41 is provided in the valve body 23A on the side facing the piston 3 of the two stacked valve bodies 23A, 23B that constitute the check valve body 23. This is because it was established.

With this configuration, the effective cross-sectional area of the notch 41 can be easily adjusted, and the piston can be shared.

In each of the above-described embodiments, the damping force characteristic on the contraction stroke is described as having multiple stages, but the damping force characteristic on the extension side may also have multiple stages, or both characteristics may have multiple stages.

[Effect of idea]

Since the hydraulic shock absorber of the present invention is as described in detail above, even if the low-speed damping force characteristic is increased, the medium-speed damping force characteristic is low and the high-speed damping force characteristic is the desired high damping force characteristic. This not only improves riding comfort, but also improves steering stability and maintains the strength of the vehicle body by increasing the damping force at high speeds.

[Brief explanation of drawings]

1 to 3 relate to the first embodiment of the present invention, in which FIG. 1 is a vertical sectional view of the main part of the hydraulic shock absorber, and FIG.
The figure is an operating state diagram showing the operating state, Figure 3 is a damping force characteristic diagram, Figure 4 is a vertical sectional view of main parts showing the second embodiment of the present invention, and Figures 5 and 6 are the present invention. In the third embodiment, FIG. 5 is a vertical sectional view of the main part, and FIG. 6 is a plan view of the check valve body. 1...Cylinder, 2...Piston rod, 3...
... Piston, 7, 8, 9 ... Valve seat, 10, 1
DESCRIPTION OF SYMBOLS 1... Disk valve, 12, 13, 21... Annular oil chamber, 19, 20... Communication passage, 22... Notch (first fixed orifice), 23... Check valve body (valve body), 24... ...notch (other fixed orifice).

Claims (1)

[Scope of utility model registration request] A piston that is slidably provided in a cylinder and defines two oil chambers in the cylinder, a disk valve on an extension side and a reduction side that are provided on both sides of the piston in the axial direction, and two oil chambers. A communication passage on an extension side and a communication passage on a contraction side are formed in the piston to communicate the chambers, and the openings on one side are respectively closed by the respective disc valves, and the openings on the other side are open to the oil chamber, respectively. , and one fixed orifice formed in one of the disc valves or the piston in order to give the oil fluid flowing through one of the communication passages both expansion and contraction rising characteristics. In the hydraulic shock absorber, at least one of the disc valves is provided with a valve body that closes the opening on the other side of the one communication passage when the hydraulic pressure in the oil chamber exceeds a predetermined value. between the valve body and the opening on the other side of the first communication passage, allowing oil fluid to flow through the communication passage even after the communication passage is closed by the valve body. A hydraulic shock absorber characterized by being provided with another fixed orifice.