JP2542932Y2 - Variable damping force type hydraulic shock absorber - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a variable damping force type hydraulic shock absorber.

2. Description of the Related Art As a hydraulic shock absorber used for a suspension device of an automobile or the like,
A variable damping force type hydraulic shock absorber capable of adjusting the generated damping force is known (see, for example, Japanese Patent Application Laid-Open No. 63-42323).

In this variable damping force type hydraulic shock absorber, a reservoir is provided between the cylinder and the outer cylinder in contact with the bottom valve by mounting the bottom valve at the lower end of the cylinder while the outer cylinder is disposed outside the cylinder. A chamber is provided, and a cylinder is further defined by a piston inserted therein into an upper liquid chamber and a lower liquid chamber. The piston is opened during its extension stroke to allow the liquid in the upper liquid chamber to flow downward. An expansion-side damping force generating valve for displacing and flowing to the liquid chamber and generating a damping force at that time, and a tuck valve for allowing the flow of liquid from the lower liquid chamber to the upper liquid chamber during the contraction stroke of the piston are provided. The bottom valve has a contraction-side damping-force generating valve that opens during the piston's contraction stroke to replace and circulate the liquid in the lower liquid chamber to the reservoir chamber and generates a damping force at that time. It is disposed a check valve that allows the flow of liquid into the lower fluid chamber from. Further, the piston has a passage connecting the upper liquid chamber and the lower liquid chamber as an extension-side damping force adjusting means, and adjusts an opening area of the passage in response to a differential pressure between the upper liquid chamber and the lower liquid chamber. An expansion side spool valve is provided, and a bottom valve is provided in the bottom valve as a compression side damping force adjusting means in response to the liquid pressure in the lower liquid chamber (in the cylinder) and the passage communicating the lower liquid chamber and the reservoir chamber. A contraction-side spool valve that adjusts the opening area of this passage is provided, and when the differential pressure between the upper liquid chamber and the lower liquid chamber changes during the extension stroke, or when the liquid pressure in the lower liquid chamber changes during the contraction stroke. In this case, the expansion-side spool valve and the contraction-side spool valve respectively change the opening area of each passage to adjust the flow rate of the liquid passing through the expansion-side damping-force generating valve and the contracting-side damping-force generating valve. The power is adjusted automatically .

However, in the above-mentioned conventional damping force variable type hydraulic shock absorber, the structure in which the expansion spool valve and the contraction spool valve are arranged on the piston and the bottom valve as damping force adjusting means, respectively. Therefore, there is a problem that the number of parts is large and the cost is high.

Also, since the piston is a component that slides in the cylinder and has a limited space for mounting other components and requires structural strength, it is desirable that the piston has a simpler structure with few mounting components. It is rare.

Therefore, the present invention is to provide a variable damping force type hydraulic shock absorber which can reduce the number of parts and reduce the cost and simplify the piston.

Means for Solving the Problems The present invention provides means for solving the above-mentioned problems,
While the interior of the cylinder is defined by a piston as an upper liquid chamber and a lower liquid chamber, a reservoir chamber is provided in contact with a bottom valve arranged at the bottom of the cylinder, and the piston is opened during its extension stroke. And an expansion-side damping force generating valve for generating a damping force while displacing the liquid in the upper liquid chamber to the lower liquid chamber is provided, and the bottom valve is opened during the contraction stroke of the piston to open the lower liquid chamber. In a damping force variable type hydraulic shock absorber provided with a contraction side damping force generation valve that generates a damping force while displacing and flowing the liquid to the reservoir chamber,
A first bypass passage communicating the reservoir chamber with the lower fluid chamber via the bottom valve, and a second bypass passage communicating the upper fluid chamber are provided. The spool valve is provided so as to be slidable, and the spool valve is formed with passage holes that normally communicate with the bypass passages, and these passage holes are responsive to the hydraulic pressure of the lower liquid chamber during the compression stroke of the piston. A pressure receiving chamber for driving the spool valve in a direction to close each of the bypass passages is provided.

When the hydraulic pressure in the lower liquid chamber increases during the compression stroke of the piston, the hydraulic pressure in the pressure receiving chamber increases, and the spool narrows the passage hole on the first bypass passage side and the passage hole on the second bypass passage side to reduce the damping on the compression side. When the damping force generated by the force generating valve and the extension side damping force generating valve is increased, and conversely, when the hydraulic pressure of the lower liquid chamber decreases during the compression stroke of the piston, the hydraulic pressure of the pressure receiving chamber decreases and the spool becomes first. The passage hole on the passage side and the passage hole on the second passage side are opened to reduce the damping force generated by the contraction side damping force generation valve and the extension side damping force generation valve.

Embodiment Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. 1 to 3, and a second embodiment will be described with reference to FIGS.

 First, a first embodiment will be described.

1 to 3, reference numeral 1 denotes a cylinder. The cylinder 1 has a bottom valve 2 fitted in a lower portion thereof and an outer cylinder 3 disposed outside the cylinder 1, and is sandwiched between the cylinder 1 and the outer cylinder 3. The space formed is the reservoir chamber 4. The reservoir chamber 4 is provided in contact with the bottom valve 2. A piston 5 is slidably fitted into the cylinder 1,
The inside of the cylinder 1 is moved by the piston 5 to the upper liquid chamber 6.
And a lower liquid chamber 7. The lower part of the reservoir chamber 4 and the cylinder 1 are filled with liquid,
Gas is sealed in the upper part of. A rod guide 8 is fitted to the upper ends of the cylinder 1 and the outer cylinder 3, and a piston rod 9 extending upward from the piston 5 is slidably held by the rod guide 8.

The piston 5 is provided with a plurality of communication holes 10 and a plurality of communication holes 11 for communicating the upper liquid chamber 6 and the lower liquid chamber 7, respectively. Communication hole
Both 10 and 11 are arranged in an annular shape, and the communication hole 10 is located inside the communication hole 11. Reference numeral 12 denotes a leaf valve mounted on the lower surface of the piston 5 as an extension-side damping force generating valve. The leaf valve 12 opens the communication hole 10 during the extension stroke of the piston 5 and allows the liquid in the upper liquid chamber 6 to flow downward. At the same time, the fluid is replaced and circulated in the liquid chamber 7, and at that time, a flow resistance is given to the liquid to generate a damping force. Reference numeral 13 denotes a spring that urges the outer edge of the leaf valve 12 upward to thereby increase the damping action of the leaf valve 12. Also,
A check valve 14 is mounted on the upper surface of the piston 5 to open the communication hole 11 during the contraction stroke of the piston 5 and close the communication hole 11 during the extension stroke. The check valve 14 includes the upper liquid chamber 6 and the upper liquid chamber 6. An opening 15 for constantly communicating the communication hole 10 inside the piston 5 is formed.

Reference numeral 16 denotes a middle cylinder disposed between the cylinder 1 and the outer cylinder 3. The middle cylinder 16 has an upper end fixed to an outer peripheral wall of the cylinder 1 via a retainer 17 and a lower end connected to the bottom valve 2. It is fitted. On the upper wall of the cylinder 1, there is a middle cylinder 16
A through hole 18 is formed to communicate a cylindrical passage 19 sandwiched between the cylinder 1 and the upper space in the cylinder 1. still,
The through hole 18 is slightly above the highest position of the piston 5 on the wall surface of the cylinder 1 (as low as possible).
The middle cylinder 16 formed at the position and disposed outside the cylinder 1 is designed to minimize the volume of the reservoir chamber 4 as much as possible.

As shown in FIGS. 2 and 3, the valve body 2a of the bottom valve 2 is formed with a through hole 20 penetrating vertically through a central portion thereof.
A cylindrical bolt member 21 is inserted from the lower surface side of 2a, and a casing 22 is screwed to a distal end portion protruding toward the upper surface side of the valve body 2a. The valve body 2a is provided with a plurality of communication holes 23 and a plurality of communication holes 24, each of which communicates in the up-down direction, and the communication holes 23, 24 are both annularly arranged.
3 is located inside the communication hole 24. Reference numeral 25 denotes a communication hole that communicates the space 26 below the valve body 2a with the reservoir chamber 4. Also, the valve body 2a
And the bolt member 21, the upper passage of the valve body 2a communicates with the through hole 27 at the center of the bolt member 21, that is, the first passage 28 that communicates the lower liquid chamber 7 and the reservoir chamber 4, and the cylindrical passage 19 penetrates. A second passage 29 communicating with the hole 27, that is, communicating the cylindrical passage 19 with the reservoir chamber 4, is formed. The first passage 28
Constitutes a first bypass passage in the present invention, and a second passage
Numeral 29 together with the cylindrical passage 19 constitutes a second bypass passage in the present invention.

Reference numeral 30 denotes a leaf valve as a compression-side damping force generating valve which is fixedly fastened to the lower surface of the valve body 2a by a bolt member 21. The leaf valve 30 opens the communication hole 23 during the compression stroke of the piston 5 to open the lower fluid. The liquid in the chamber 7 is displaced and circulated through the reservoir chamber 4 and, at that time, a flow resistance is given to the liquid to generate a damping force. 31 is the valve body
A check valve mounted between the valve body 2a and the casing 22 on the upper surface side of 2a. The check valve 31 includes a check plate 32 and a check spring 33. In addition, an opening 34 for constantly communicating the communication hole 23 and the first passage 28 is formed.

On the other hand, the casing 22 includes a lid 36 having an orifice 35.
Is fixed to the upper end thereof, and a spool valve 37 is slidably fitted therein. Spool valve
37 is provided with a flange portion 38 which is fitted into the casing 22 to define the inside thereof into two upper and lower chambers, and a cylindrical portion 39 which is fitted into the through hole 27 of the bolt member 21. The upper chamber is a pressure receiving chamber 40 into which the liquid in the lower liquid chamber 7 is introduced via the orifice 35. On the other hand, the cylindrical portion 39 has a hollow portion 41 whose end is open to the space 26.
In addition, a communication hole 42 that communicates the hollow portion 41 with a lower room in the casing 22 is formed, and the lower room in the casing 22 communicates with the communication hole 42, the hollow portion 41, the space 26, Hole 25
Through the reservoir chamber 4. A spring 43 is provided in a lower room in the casing 22, and the spool valve 37 is constantly urged upward by the spring 43. In the case of this embodiment, a dash pot for suppressing a sudden displacement of the spool valve 37 is constituted by the orifice 35. For this reason, when the liquid pressure of the lower liquid chamber 7 exceeds the set pressure during the compression stroke of the piston 5 and the liquid in the lower liquid chamber 7 once flows into the pressure receiving chamber 40,
Most of the liquid in the pressure receiving chamber 40 does not immediately escape to the lower liquid chamber 7 because of the orifice 35 even when the piston 5 moves to the extension stroke, and remains largely as it is, and the spool valve 37 remains in the lowered state. Is maintained. The operating pressure of the spool valve 37 is determined by setting the set load of the spring 43, the spring constant, the diameter of the orifice 35, and the like.

Further, in the cylindrical portion 39 of the spool valve 37, a pair of annular grooves 44, 45 are formed so as to communicate with the first passage 28 and the second passage 29, respectively, when the spool valve 37 is in the highest position, Each of the annular grooves 44 and 45 communicates with the hollow portion 41 by passage holes 46 and 47 formed in the column portion 39.
The first passage 28 and the second passage 29 are reduced in a portion overlapping each other with the annular grooves 44 and 45 as the spool valve 37 is lowered, and the opening area is reduced, so that the spool valve 37 has a set amount. When it descends, it becomes completely closed. Therefore, the passage hole from the first passage 28 and the second passage 29
The flow rate of the liquid flowing into the reservoir chamber 4 after passing through 46 and 47 is
As the spool valve 37 is lowered, that is, as the hydraulic pressure in the lower liquid chamber 7 increases, the pressure is reduced.

In FIG. 1, reference numeral 48 denotes a rebound stopper fixed to the piston rod 9, reference numeral 49 denotes a rebound rubber fixed to the rebound stopper 48, and reference numeral 50 denotes a rod seal provided above the rod guide 8. .

With the above configuration, the variable damping force type hydraulic shock absorber according to the present invention basically operates as follows.

That is, during the contraction stroke of the piston 5, the piston 5
The side check valve 14 is opened to open the upper liquid chamber 6 and the lower liquid chamber 7
And the hydraulic pressure inside the cylinder 1 rises by the amount of the piston rod 9 to enter, the leaf valve 30 on the bottom valve 2 side opens, and the liquid in the lower liquid chamber 7 communicates with the opening 34 of the check plate 32 After passing through the hole 23, the space 26, and the communication hole 25, it flows into the reservoir chamber 4, and at this time, a damping force is generated by the leaf valve 30 (see FIG. 1). In the extension stroke of the piston 5, the check valve 14 on the piston 5 side closes and the hydraulic pressure in the upper liquid chamber 6 rises, whereby the leaf valve 12 is opened and the liquid in the upper liquid chamber 6 The liquid flows into the lower liquid chamber 7 through the opening 15 and the communication hole 10, and at this time, a damping force is generated by the leaf valve 12. At this time,
The check valve 31 on the bottom valve 2 side is opened, and the liquid in the reservoir chamber 4 flows into the lower liquid chamber 7 through the communication hole 25, the space 26, and the communication hole 24.

The variable damping force type hydraulic shock absorber operates as follows according to the liquid pressure in the lower liquid chamber 7 during the compression stroke of the piston 5.

In the state where the hydraulic pressure of the lower liquid chamber 7 acting on the pressure receiving chamber 40 via the orifice 35 during the compression stroke of the piston 5 does not reach the set pressure, as shown in FIG.
37 is maintained at the highest position by the elastic force of the spring 43, the first passage 38 and the second passage 39, or the passage hole 4
6,47 is completely open. Therefore, during the compression stroke of the piston 5, the amount of liquid flowing from the lower liquid chamber 7 through the first passage 28 to the passage hole 46, the space 26, the reservoir chamber 4,
The amount of liquid flowing from the upper liquid chamber 6 to the passage hole 47, the space 26, and the reservoir chamber 4 through the cylindrical passage 19 and the second passage 29,
The flow rate passing through the leaf valve 30 decreases, and the damping force generated there decreases (see the arrow in FIG. 1 for the flow of the liquid). In the extension stroke of the piston 5, the upper liquid chamber 6 passes through the cylindrical passage 19 and the second passage 29, and the communication holes 47,
The amount of the liquid flowing into the space 26 and the reservoir chamber 4 increases, and the flow rate passing through the leaf valve 12 decreases accordingly, and the damping force generated there decreases.
(See the arrow in the figure).

When the hydraulic pressure of the lower liquid chamber 7 acting on the pressure receiving chamber 40 via the orifice 35 during the compression stroke of the piston 5 becomes higher than the set pressure, the spool valve 37 responds to the liquid pressure of the lower liquid chamber 7, As shown in the figure, it descends against the spring 43 to reduce the opening area of the first passage 28 and the second passage 29. The first passage 28 and the second passage 29 are completely closed when the spool valve 37 is lowered by a set amount. Therefore, during the compression stroke of the piston 5, the amount of liquid flowing from the lower liquid chamber 7 through the first passage 28 to the passage hole 46, the space 26, and the reservoir chamber 4 and the amount of liquid flowing from the upper liquid chamber 6 to the cylindrical passage 19 And the amount of liquid flowing through the second passage 29 to the passage hole 47, the space 26, and the reservoir chamber 4 is reduced or completely eliminated, and the leaf valve 30 is accordingly reduced.
The damping force generated at the time increases. Also, in the extension stroke of the piston 5, the spool valve 37 which has been lowered in the contraction stroke is maintained as it is, so that the upper liquid chamber 6 passes through the cylindrical passage 19 and the second passage 29 and passes through the passage hole 47. ,
The amount of liquid flowing into the space 26 and the reservoir chamber 4 is reduced or completely eliminated, and the damping force generated in the leaf valve 12 is increased accordingly (the flow of liquid during the contraction stroke and the extension stroke of the piston 5). Is the arrow in FIG. 3).

Next, a second embodiment of the present invention will be described. The variable damping force type hydraulic shock absorber of this embodiment is different from the first embodiment only in the structure of the dash pot portion interposed between the working chamber 40 and the lower liquid chamber 7, and is different from the first embodiment. Since the structures are the same, only the structure of the dashpot portion will be described in detail, and the same reference numerals will be used for the same portions.

4 to 6, reference numeral 136 denotes a lid fixed to the upper end of the casing 22. The lid 136 is provided with an orifice 35 at a central portion thereof and has a lower surface surrounding the orifice 35. An annularly protruding valve seat 51 is provided. An orifice groove 52 is formed in a part of the valve seat 51. A retainer 53 is fixed to the upper end of the casing 22 together with the lid 136.A check plate 54 and a check spring 55 are interposed between the lid 136 and the retainer 53, and the check plate 54 is The spring of the check spring 55 is pressed against the valve seat 51. Retainer 53 and check plate
Openings 56 and 57 are provided in the 54, respectively, and the pressure receiving chamber 40 and the lower liquid chamber 7 are always in conduction through the openings 56 and 57, the orifice groove 52 and the orifice 35. The opening area of the orifice groove 52 is set smaller than the opening area of the orifice 35.

Because of the above configuration, the piston (not shown)
In the state where the hydraulic pressure of the lower liquid chamber 7 acting on the pressure receiving chamber 40 via the orifice 35 during the contraction stroke does not reach the set pressure, as shown in FIG. 4, the spool valve 37 is kept at the highest position. Has been maintained. Since the spool valve 37 does not descend, the first passage 28 and the second passage 29 remain unrestricted as in the case of the first embodiment. In any case during the stroke, the generated damping force is small.

When the displacement speed of the piston is increased from such a state, and the pressure of the lower liquid chamber 7 acting on the pressure receiving chamber 40 via the orifice 35 during the contraction stroke of the piston becomes higher than the set pressure, as shown in FIG. Then, the liquid in the lower liquid chamber 7 passes through the orifice 35 and pushes down the check plate 54, flows into the pressure receiving chamber 40 from the openings 57 and 56, and lowers the spool valve 37 against the spring 43. When the spool valve 37 is lowered in this manner, the first passage 28 and the second passage 29 are throttled, and the damping force generated during the compression stroke of the piston increases accordingly. Further, when the piston rises from this state and the liquid pressure in the lower liquid chamber 7 decreases, the check plate 54
Pressed again. For this reason, the liquid in the pressure receiving chamber 40 attempts to return to the lower liquid chamber 7 through the openings 56 and 57, the orifice groove 52, and the orifice 35, but the flow path is largely restricted by the orifice groove 52. Most of the liquid does not immediately fall into the lower liquid chamber 7 and remains as it is. Since the spool valve 37 is thus maintained in a substantially lowered state, the damping force generated during the extension stroke of the piston increases.

The variable damping force type hydraulic shock absorber of this embodiment has an orifice groove only when the liquid flowing into the pressure receiving chamber 40 returns to the lower liquid chamber 7.
Since the structure 52 functions as a restrictor, the opening area of the orifice groove 52 can be set freely without considering the effect when the liquid flows into the pressure receiving chamber 40 from the lower liquid chamber 7. Therefore, it is possible to arbitrarily set the time required for the spool valve 37 to return from the lowered state to the original state, and to obtain more desirable damping characteristics.

Effect of the Invention As described above, the present invention provides the reservoir chamber via the bottom valve, the first bypass passage communicating with the lower liquid chamber, and the second bypass passage communicating with the upper liquid chamber. The bottom valve is provided with a spool valve that slidably intersects the bottom valve, and the spool valve is formed with passage holes that normally communicate with the bypass passages, and these passage holes are formed in the lower liquid chamber during the compression stroke of the piston. A pressure receiving chamber that drives the spool valve in a direction to close each of the bypass passages in response to the hydraulic pressure of the piston valve is provided. By adjusting the opening area of the passage hole on the first bypass passage side and the passage hole on the second bypass passage side by the spool valve, the contraction side damping force generating valve and the extension side damping are provided. Since the respective damping forces generated by the force generating valves can be simultaneously adjusted, the cost can be reduced by reducing the number of parts, and the piston can be simplified.

[Brief description of the drawings]

FIGS. 1, 2, and 3 are sectional views showing a first embodiment of the present invention, and FIGS.
FIG. 3 is a sectional view showing a second embodiment of the present invention. 1 ... cylinder, 2 ... bottom valve, 4 ... reservoir chamber, 5 ... piston, 6 ... upper liquid chamber, 7 ... lower liquid chamber, 12 ... leaf valve (extension side damping force generating valve), 19 ...
... cylindrical passage (second bypass passage), 28 ... first passage (first bypass passage), 29 ... second passage (second bypass passage), 30 ... leaf valve (compression side damping force generating valve), 37
... Spool valve, 46, 47 ... Passage hole.

Claims (1)

(57) [Scope of request for utility model registration] 1. A cylinder having an upper liquid chamber and a lower liquid chamber defined by a piston, and a reservoir chamber provided in contact with a bottom valve disposed at a bottom of the cylinder.
The piston is provided with an expansion-side damping force generation valve that opens during the expansion stroke to displace the liquid in the upper liquid chamber to the lower liquid chamber and generates a damping force, and the bottom valve is configured to contract the piston. In the variable damping force type hydraulic shock absorber provided with a contraction-side damping force generating valve that opens during the stroke and displaces the liquid in the lower liquid chamber to the reservoir chamber and generates damping force, via the bottom valve The reservoir chamber is provided with a first bypass passage communicating with the lower liquid chamber, and a second bypass passage communicating with the upper liquid chamber, and a spool valve traversing each of these bypass passages is slidably mounted on the bottom valve. The spool valve is provided with passage holes that normally communicate with the bypass passages, and these passage holes are adapted to the hydraulic pressure of the lower liquid chamber during the compression stroke of the piston. Damping force variable hydraulic shock absorber is characterized by providing the pressure receiving chamber to drive the spool valve in a direction for closing the respective bypass passages and.