JPH0285533A - Variable damping force hydraulic shock absorber - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a hydraulic shock absorber whose damping force can be changed.

(Prior Art) As a conventional variable damping force type hydraulic shock absorber, for example, one described in Japanese Utility Model Application Publication No. 164836/1983 is known.

In this conventional structure, as a means for generating damping force during the extension stroke, an orifice hole is bored in the piston to communicate the upper liquid chamber and the lower liquid chamber, and a disk pulp is provided to open and close this orifice hole. Furthermore, a communication passage is formed in the piston rod in parallel with the orifice hole to communicate the upper liquid chamber and the lower liquid chamber, and the cross-sectional area of the passage is changed in the middle of the communication passage to adjust the damping force characteristics. A damping force variable means for switching was provided.

Therefore, when it is desired to increase the generated damping force, if the communication path is blocked by the damping force variable means, during the extension stroke, the hydraulic fluid in the -L liquid chamber passes only through the orifice hole, opens the disc valve, and opens the upper liquid chamber. A damping force is generated at the orifice hole and the opening part of the disc valve, resulting in the damping force characteristic as shown in Figure 9 (■).6 If you want to lower the generated damping force, you can change the The flow area of the communication path is increased by the change stage. Then, during the extension stroke, the working fluid in the upper fluid chamber flows toward the lower fluid chamber through two paths: the orifice hole and the communication path. In this way, the flow path area is expanded, so for example, as shown in
The generated damping force can be lowered.

(Problem to be Solved by the Invention) However, in the conventional variable damping force type hydraulic shock absorber described in I-5, there is a communication path in the = Im row with respect to the orifice hole which is a means for generating damping force. As shown in Figure 9, in the low piston speed range, the damping force is generated by the passage section as the upper body, and in the medium and high piston speed range, the damping force is generated mainly by the restriction and orifice hole generated in the disc valve. occurs, and there is a problem in that the damping force variable rate cannot be made equal in the low piston speed range and in the middle and high piston speed range.

Furthermore, since the damping force characteristics of each range cannot be linear with respect to the piston speed,
The problem was that it was not possible to achieve both handling stability and ride comfort in all ranges.

The present invention was made by focusing on the conventional problems as described above, and it is possible to obtain a linear damping force characteristic in the extension stroke.
The objective is to provide a variable damping force hydraulic shock absorber that achieves both handling stability and ride comfort in all ranges.

(Means for Solving the Problems) In order to achieve the above-mentioned objects, the variable damping force type hydraulic shock absorber of the present invention has an interior defined by a piston into an upper liquid chamber and a lower liquid chamber, A cylinder filled with hydraulic fluid, an inner groove and an outer groove formed double inside and outside on the end surface of the lower liquid chamber side of the piston, and an inner sheet formed between the two grooves and an outer periphery of the outer groove. an outer sheet surface that has been
an extension side disc valve provided on the lower liquid chamber side end surface of the piston in contact with both seat surfaces to open and close both grooves;
A first communication passage that communicates the inner groove and the upper liquid chamber, a second communication passage that communicates the outer groove and the upper liquid chamber, and a variable iris provided in the middle of one of the two communication passages. Ta.

(Function) In the variable damping force type hydraulic edge 1◆i device of the present invention, during the extension stroke,
That is, when the piston moves in a direction to narrow the volume of the upper liquid chamber, the following operation is performed.

In other words, when the liquid in the upper liquid chamber rises due to the extension stroke,
The liquid in the inner groove and the outer groove is raised through the first and second communication passages.

Then, the growth side disc valve receives the hydraulic pressure in both grooves, and the growth side disc valve is opened by a predetermined hydraulic pressure.
l' from the upper liquid chamber via the first communication path and the second communication path.
ff Working fluid flows into the liquid chamber.

In other words, the work that goes through the first communication path! J] From there, the liquid passes through the inner groove, then passes through the gap (restriction) created between the inner seat surface and the expansion side valve disk by opening the expansion side disc valve, and flows to the outside groove side. From there, it also passes through the gap (throttle) formed between the outer seat surface and the growth side disc valve by opening the growth side disc valve.
It flows out into the lower liquid chamber.

In addition, the hydraulic fluid passing through the second communication passage passes from the outer groove, through the gap (restriction) formed between the outer seat surface and the growth side damping valve by opening the growth side disc valve, to the lower fluid chamber. flows out to.

As described above, in the case of the present invention, between the expansion side disc valve and the piston, there are two throttles in series at the inner seat surface position and the outer seat surface position, and in the low speed range of the piston, these Damping force is generated based on the throttles, and in medium and high speed ranges where these throttles are wide open, damping force is generated on the side of the communication path that includes the variable orifice.

In other words, when the piston is in a low-speed operation range, a restriction created at the outer seat surface position will reduce the flow of fluid before and after the restriction based on the closing force of the expansion-side disc valve when the piston speed is in the low-speed area. The rate of change of the pressure difference increases, and the rate of change of the damping force also increases.On the other hand, when the piston speed is in the low speed range, the throttle at the inner seat surface position increases. Therefore, there is a small change in the hydraulic pressure difference before and after the throttle at this inner seat surface position, and a small change in the damping force.

In this way, the damping force characteristics due to the aperture at both seat surface positions are symmetrical, with one having a large rate of change and the other having a small rate of change, so both damping force characteristics are added in series. The characteristics obtained are close to a first-order linear rate of change.

In medium and high speed ranges, a damping force is generated based on the flow path cross section of both communicating passages, and in this case, a first-order linear characteristic is obtained.

In addition, if you want to change the range of the damping force characteristics, you can change the cross-sectional area of the communication path using a variable orifice provided in the middle of one of the communication paths.
As the flow rate ratio of the hydraulic fluid changes, the range of the damping force characteristics changes.

(Example) Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

First, the configuration of the embodiment will be explained.

FIG. 1 is a sectional view showing the main parts of a variable damping force type hydraulic shock absorber according to an embodiment of the present invention, and 1 in the figure indicates a cylindrical cylinder. This cylinder 1 is defined by a slidably mounted piston 2 into an upper liquid chamber A and a lower liquid chamber B, and the inside thereof is filled with a hydraulic fluid such as oil.

The piston 2 has a retainer 4 at the tip of the piston rod 3. Washer 5. Compression side disc valve 6, piston body 7, first expansion side disc valve 8, second expansion side disc valve 9. Washer lO.

Spring seat 11. Install the springs 12 in sequence,
It is configured to be fastened with a nut 13.

More specifically, in the piston body 7, a pressure side communication passage 7a is bored in the axial direction near the outer periphery, communicating the upper liquid chamber A and the lower liquid chamber B. The pressure side communication passage 7a is provided at three locations, as shown in FIG. 2 showing the top surface of the piston body 7 and FIG. Around the
A pressure side sheet surface 7b is formed. As shown in FIG. 1, the pressure side disc valve 6 is provided in contact with this pressure side seat surface 7b.

Further, on the lower surface of the piston body 7, an annular inner groove 7C and an outer groove 7d are provided at a position inside the pressure side communication passage 7a.
are formed (see Figure 3).

The inner groove 70 has six first communication holes (first
The communication path) 7e communicates with the upper liquid chamber A (the second.
3), and an inner sheet surface 7f is formed on the outer periphery of the inner groove 70.

Note that a boss portion 7g is provided inside the inner groove 70.

On the other hand, an outer seat surface 7h is formed on the outer periphery of the outer groove 7d, and the outer groove 7d is connected to an annular structure 3a formed between the piston body 7 and the piston rod 3 via the second communication hole 7j. is communicated with.

That is, a through hole 3b is bored in the axial center of the piston rod 3 upward from the lower end, and the through hole 3b is opened to the upper liquid chamber A at a position above the piston 2 and is opened to the upper liquid chamber A. A boat 3c is bored in the radial direction, and the annular structure 3a
A lower boat 3d is formed at a position corresponding to , which communicates the annular structure 3a with the through hole 3b.

Therefore, the outer groove 7d is connected to the second communication hole 7j and the annular structure 3.
8, a lower boat 3d, a through hole 3b, and an upper boat 3c.

A large diameter communication hole 13a is formed in the lower part of the nut 13 to communicate the communication hole 3b with the lower liquid chamber B. A check valve 14 is provided that allows the flow of hydraulic fluid from the through hole 3a to the lower fluid chamber B, and conversely restricts the flow of hydraulic fluid from the through hole 3a to the lower fluid chamber B. This check valve 14 includes a valve body 14 fitted into a communication hole 13a of a nut 13.
a, a check plate 14b that abuts against the valve body 14a, and a spring 14c that biases the check plate 14b in the valve closing direction.

By the way, a first extension side disc valve 8 is provided on the lower surface of the piston body 7 in contact with the inner seat surface 7f and the outer seat surface 71. The inner groove 7c and the outer groove 7d can be opened and closed. Furthermore, a second expansion side disc valve 9 is provided on the lower surface of the first expansion side disc valve 8, and the outer peripheral portion of the second expansion side disc valve 9 is formed to have an outer diameter that corresponds to the inner seat surface 7r. Spring seat on the periphery of the expansion side disc valve 9! The biasing force of the spring 12 is applied via +.

Furthermore, the through hole 3 constituting the passage C (second communication passage)
Inside C, an adjuster 15 as a variable orifice is rotatably provided while being sandwiched between an upper thrust bush 16 and a lower thrust bush 17.

The adjuster 15 is formed into a cylindrical shape with a hollow portion 15a, and has an upper small-diameter orifice hole 15b and an upper large-diameter hole 15b at positions corresponding to the upper port 3c and the lower port 3d, respectively. A diameter orifice hole 15c, a lower small diameter orifice hole 15d, and a lower large diameter orifice hole 15e having a larger diameter are bored in the radial direction, and between the upper port 3c and the lower port 3d and the hollow part 15a. The cross-sectional area of the flow path can be changed.

Note that the adjustment element 15 is rotated by a control rod 18 provided within the piston rod 3. This control rod 18 extends to the upper end of the piston rod 3, and is configured to be given rotational force by an actuator (not shown) provided at a portion of the piston rod 3 that is attached to the vehicle body.

By the way, an outer cylinder 19 is provided outside the cylinder 1 as shown in FIG. A reservoir chamber filled with hydraulic fluid is formed.

Furthermore, a base 20 defining the lower liquid chamber B and a reservoir chamber is provided at the bottom of the cylinder 1.

This base 20 includes a growth side communication path 20a and a compression side communication path 20a.
A check plate 21 is provided on the upper surface of the base 20 to allow only the flow of hydraulic fluid from the reservoir chamber to the lower fluid chamber B in the expansion side communication path 20a. A first pressure-side disc valve 22 and a first pressure-side disc valve 22 are provided on the lower surface in contact with the inner seat surface 20c in order to generate a damping force when the hydraulic fluid flows from the lower liquid chamber B to the reservoir chamber via the pressure-side communication path 20b. Outer seat surface 2
A second pressure side disc valve 23 that is in contact with 0d is provided.

These double pressure side disc valves 22.23 form a series two-stage valve, and both positive side disc valves 22.23
A washer 24 is provided between the two to allow the first pressure disc valve 22 to flex.

Further, an orifice 20e is provided on the outer sheet surface 20d.
is stamped.

Next, the operation of the embodiment will be explained.

First, the operation during the extension stroke in which the piston 2 moves in a direction to narrow the volume of the upper liquid chamber A will be described.

During the extension stroke, the hydraulic fluid in the upper fluid chamber A flows into the lower fluid chamber B as the hydraulic pressure in the upper fluid chamber A increases. At this time, there are two paths for the hydraulic fluid to flow. Firstly, the first path is from the first communication hole 7e through the inner groove 70 to the first expansion side disc valve 8 at the inner seat surface 7f position. and open the second expansion side disc valve 9, and further open the outer groove 7.
There is a path that passes through d and flows into the lower liquid chamber B by opening the first expansion side disc valve 8 at the position of the outer seat surface 7h.

In addition, as a second path, the liquid flows from the upper liquid chamber A, passes through the upper port 3c, and flows into the hollow part 15a via either the mountain top orifice hole 15b or 15c, and the liquid flows into the hollow part 15a.
From there, it passes through the lower boat 3d and the annular groove 38 through either of the lower rain orifice holes 15d and 15e, and then the second
This path passes through the communication hole 7j, reaches the outer groove 7d, opens the first expansion side disc valve 8 at the position of the outer seat surface 7h, and flows into the lower liquid chamber B.

In this way, in this embodiment, the inner groove 7c and the outer groove 7
The pressure distribution applied to both elongation side disc pulps 8.9 at d changes, and throttles with a predetermined opening degree occur in series at the inner sheet surface 7f position and the outer sheet surface 7h position, and in the low speed operating range. , the hydraulic fluid is throttled by these throttles and a damping force is generated. Furthermore, in the medium/high speed operation range, the opening degree of these throttles becomes large, and a damping force is generated based on the cross-sectional area of the flow path formed by the first communication hole 7e and each orifice hole 15b-15e.

That is, FIG. 5 shows the hydraulic pressure difference between the inner groove 7c and the outer groove 7d, which sandwich the throttle at the inner seat surface 7f position.
In the low speed range, the rate of change is small (and in the medium and high speed ranges, the rate of change is large and linear.

Further, FIG. 6 shows the hydraulic pressure difference between the outer groove 7d sandwiching the throttle at the outer seat surface 7h position and the lower liquid chamber B.
In the low speed range, the rate of change is thick (and in the medium and high speed ranges, the rate of change is small (and linear).

Since these are in a series relationship, the damping force characteristic of this hydraulic shock absorber is the sum of both characteristics.In other words, as shown in Figure 7, the damping force characteristic is the sum of both characteristics. Over the entire region, the characteristic is proportional to the piston speed close to a linear straight line.

By the way, in this second path, by rotating the adjuster 15, the upper port 3c and the lower port -3d are connected to the upper two orifice holes 15b, 15c and the lower inner orifice hole 1.
5d and 15e, or both ports 3 without matching each orifice hole 15b-15e.
It is possible to change the damping force characteristics by changing the cross-sectional area of the flow path by completely blocking the flow paths c and 3d, and by changing the flow rate ratio based on the cross-sectional area.

That is, in FIGS. 5 to 7 and FIG. 8, which will be described later, ■ indicates that the two vehicle diameter orifice holes 15c and 15e are aligned with both ports 3c and 3d, and ■ indicates that both vehicle diameter orifice holes 15b and If 15d is matched, ■ is both Po)
-3c and 3d are cut off.

In addition, during the extension stroke as described above, the check plate 21 of the base 20 is opened and the hydraulic fluid in the reservoir chamber is transferred to the lower fluid chamber B in order to compensate for the change in volume caused by the withdrawal of the piston rod 3. is flowing into the country.

Next, the operation during the pressure stroke in which the piston 2 moves in a direction to narrow the volume of the lower liquid chamber B will be described.

Even during the pressure stroke, between the upper liquid chamber A and the lower liquid chamber 8, 2
The hydraulic fluid flows through two parallel channels.

That is, the first flow path is a flow path that runs from the lower liquid chamber B through the communication path 7a, opens the pressure side disc valve 6, and reaches the upper liquid chamber A. In addition, the second flow path is opened from the lower liquid chamber B by opening the check valve 14 provided in the nut 13 at the lower end of the piston rod 3, and connecting the communication hole 13a to either of the orifice holes 15b and 15C to the upper part. This is a flow path that flows to the upper liquid chamber A via the boat 3c.

Further, during this pressure stroke, the hydraulic fluid also moves between the lower fluid chamber B and the reservoir chamber via the base 20. That is, the hydraulic fluid in the lower fluid chamber B flows from the pressure side communication path 20b to the first
The pressure side disc valve 22 is opened, and in the case of a low speed range, it passes through the carved orifice 20e, and also
In the case of high speed range, the second pressure side disc valve 23 is opened and the air flows into the reservoir chamber.

Therefore, a low damping force is generated in the orifice 20e in the low speed range, and a higher damping force is generated in the second pressure side disc valve 23 in the middle and high speed ranges.

Also, in the case of this pressure stroke, by rotating the adjuster 15,
Both orifice holes 15b, 1 aligned with the upper port 3c
By selectively switching 5c, the damping force characteristics can be changed as shown in FIG. In this FIG. 8, ■■■ indicates the case where each orifice hole 15b-15e is aligned with both ports 3c and 3d in the same manner as described above, and the dotted line indicates the damping force characteristic at the base 20. There is.

As explained above, in the variable damping force type hydraulic shock absorber of this embodiment, during the extension stroke, the damping force characteristics are
First-order linear characteristics are obtained from low to medium and high speeds, and across all ranges, resulting in damping force with an excellent balance between handling stability and ride comfort across all ranges. It has the characteristic of being controllable.

Further, the outer groove 7d and the inner groove 7c both have a simple shape and are easy to manufacture.Moreover, by adjusting the widths of both grooves 7c and 7d, it is possible to easily connect the first expansion side disc. The pressure-receiving area of the valve 8 can be adjusted, and by increasing the pressure-receiving area, the opening performance of the first expansion side disc valve 8 is improved, and the generation of lower damping force is realized, and the pressure-receiving area of the inner groove 70 can be adjusted. It has the characteristic that it can easily be made to generate a high damping force by making it small.

Although the embodiments of the present invention have been described above in detail with reference to the drawings, the specific configuration is not limited to these embodiments, and the present invention may be modified without departing from the gist of the present invention. included.

For example, in the embodiment, the variable orifice is provided in the second communication path, but the variable orifice may be provided in the first communication path.

Further, in the embodiment, an example is shown in which a piston rod is used as the second communication passage, but this second communication passage may also be formed in the piston body, and a part of this second communication passage may be formed in the piston body. , may be shared with the first communication path.

(Effects of the Invention) As explained above, with the variable damping force hydraulic shock absorber of the present invention, it is possible to obtain first-order linear damping force characteristics in both the low piston speed range and the medium and high speed ranges. As a result, it is possible to achieve both steering stability and ride comfort in all ranges.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing the main parts of a variable damping force type hydraulic shock absorber according to an embodiment of the present invention, Fig. 2 is a plan view showing the top surface of the piston of the embodiment, and Fig. 3 is a bottom view of the piston. Bottom view, 4th
The figure is a sectional view showing the base of the embodiment, Figure 5 is a graph showing the relationship between the pressure difference between the inner groove and the outer groove and the piston speed during the extension stroke of the embodiment, and Figure 6 is the outer groove of the embodiment. A graph showing the relationship between the hydraulic pressure difference with the lower liquid chamber and the piston speed, FIG. 7 is a graph showing the relationship between the damping force generated during the extension stroke of the embodiment and the piston speed, and FIG. A graph showing the relationship between the damping force generated in the pressure stroke and the piston speed, and FIG. 9 is a graph showing the damping force characteristics of a conventional example. A... Upper liquid chamber B... Lower liquid chamber C... Passage (second communication passage) D... Reservoir chamber ■... - Cylinder 2... Piston 3a... - Annular groove (second Communication path) 3b...Through hole (second communication path) 3c...Upper port (second communication path) 3d...Lower port (second communication path) 7...Inside of piston body 70-... Side groove 7d...Outer groove 7e...First communication hole (first communication path) 7f...-Inner seat surface 7h...Outer seat surface 7J...Second communication hole 8...First extension Side disc valve 15...Adjustor (variable orifice) Patent application Hito Atsugi Auto Parts Co., Ltd. Figure 5 Figure 6 Piston movement Figure 7 Piston movement

Claims (1)

[Scope of Claims] 1) A cylinder whose interior is defined by the piston into an upper liquid chamber and a lower liquid chamber, and which is filled with hydraulic fluid, and an inner and outer cylinder formed on the end surface of the lower liquid chamber side of the piston. an inner seat surface formed between the two grooves and an outer seat surface formed on the outer periphery of the outer groove; and a lower portion of the piston in contact with both seat surfaces to open and close both grooves. an expansion-side disc valve provided on the end surface of the liquid chamber; a first communication passage that communicates the inner groove with the upper liquid chamber; a second communication passage that communicates the outer groove with the upper liquid chamber; A variable damping force type hydraulic shock absorber, comprising: a variable orifice provided in the middle of one of the passages;