JPS5912438Y2 - hydraulic shock absorber - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hydraulic shock absorber, and more particularly to a gas-filled hydraulic shock absorber that is extremely suitable for being installed in automobiles and the like to absorb vibrations.

Generally, a gas-filled hydraulic shock absorber has a damping force generating mechanism (generally a valve mechanism) that generates a resistance force in both reciprocating directions.

However, in this type of gas-filled hydraulic shock absorber, a piston-piston rod assembly is slidably inserted into an inner cylinder containing oil, and the piston-piston rod assembly reciprocates within the inner cylinder. A valve mechanism is provided on the piston portion that acts to generate hydraulic resistance against the operation in both directions, and an outer cylinder is loosely fitted into the inner cylinder to form a reservoir chamber between the two. , the lower part of this reservoir chamber accommodates the oil liquid, and the lower part of the reservoir chamber and the chamber below the piston of the inner cylinder communicate with each other through a communication hole that does not have a restricting effect on the flow of the oil liquid. A gas chamber filled with high-pressure gas was provided in the upper part, and the gas chamber compensated for the volume when the piston rod moved into and out of the inner shell.

However, in this structure, the pressure change in the chamber below the piston as the piston descends is directly propagated to the gas chamber through the communication hole that does not have a throttling effect, so that the gas pressure in the gas chamber is controlled by the valve corresponding to the piston speed. If the pressure is too large to generate in the chamber below the piston to open the valve element against the valve load of the mechanism, pressure below atmospheric pressure (hereinafter referred to as negative pressure) will occur in the chamber above the piston. It is not possible to secure a predetermined resistance force.

Therefore, in order to generate a specified resistance force without generating negative pressure in the chamber above the piston, it is necessary to fill the gas chamber with extremely high pressure gas (for example, 20 atmospheres or more).
This high pressure constantly acts on the sealing member installed inside,
The amount of wear on the sealing member is large, and as a result, the function of maintaining internal airtightness or liquidtightness is significantly reduced, and if it breaks, it is extremely dangerous.

Furthermore, it has many drawbacks, such as the need for a sealing member that can withstand high pressure, making it impossible to reduce costs.

Furthermore, in order to reduce manufacturing costs, in this type of known shock absorber, the high pressure gas and oil are brought into direct contact with each other, so that the high pressure gas in the gas chamber is reduced by aeration that occurs during vehicle operation or operation. invades the inside of the inner letter.

For this reason, it is necessary to return the air that has entered the inner cylinder to the reservoir chamber.

For this purpose, a return passage is required, but since the pressure in the reservoir chamber forming the outer cylinder increases somewhat during the compression stroke, it is necessary to prevent air from entering the inner cylinder through the return passage. It is necessary to provide a check valve in this return flow path.

Various structures have been announced so far to fulfill such functions.

For example, Japanese Utility Model Publication No. 48-25495 discloses that a lip is integrally provided at the lower end of a sealing member for sealing the penetration part of a piston rod, and the lip allows a flow path of fluid from inside the cylinder to a reservoir chamber, while A dual-tube hydraulic shock absorber is disclosed that is a one-way valve that acts to block fluid flow from the chamber into the cylinder.

However, the hydraulic shock absorber with the above structure has a lip integrally provided at the lower end of the sealing member, and from a manufacturing standpoint, there is a limit to how thin the base of the lip can be made. It becomes thicker and becomes bulkier to operate as a one-way valve.

In addition, since the sealing member and the lip are integrated and made of the same material, if a material with a certain degree of rigidity is selected to suit the lip's one-way valve function, the sealing performance against the piston rod will be poor; In order to ensure sealing performance, the lip must be soft to some extent, which has the drawback of deteriorating the one-way valve function of the lip.

Furthermore, the movement of the sealing member accompanying the movement of the piston rod is directly transmitted to the lip, resulting in a deterioration in its function as a one-way valve.

Therefore, the present invention has a damping force generation mechanism in the piston that operates in both expansion and contraction, and can generate resistance force in both expansion and contraction at extremely low gas pressure, and is a valve that always operates properly as a one-way valve and has a long life. The object of the present invention is to provide a hydraulic shock absorber having a mechanism.

A specific example of the present invention will be described below.

FIG. 1 is a sectional view of a shock absorber according to the present invention, with number 1
, 2 are mounting rings for mounting on the sprung and unsprung parts of the vehicle, respectively.

One end of a piston rod 3 is fixed to the mounting ring 1 by known means, and the other end of the piston rod 3 is provided with a disc valve 10 as a damping force generating means for generating both expansion and contraction damping force in the shock absorber. A piston 11 having a piston 11 is fixed thereto.

The piston 11 slides inside the inner cylinder 4 filled with oil.

The upper end of the inner cylinder 4 is sealed by a rod guide 9 that guides the piston rod 3, while the lower end of the inner cylinder 4 is tightly fitted into a bottom cap 12 fixed to the mounting ring 2 by known means. Retained.

There is a throttle hole 5 near the lower end of the inner cylinder 4, and this throttle hole 5 connects the inside of the inner cylinder 4, the outside of the inner cylinder 4, and the outer wall surface of the bottom cap 12 to seal the lower end of the outer cylinder 13. It communicates with the annular space defined by the interior of the space.

The annular space is divided into a gas chamber 6A filled with low-pressure gas and an oil chamber 6B filled with oil, forming a volume compensation chamber or reservoir chamber 6.

The piston 11 is slidably disposed within the inner cylinder 4, and the inner cylinder 4 is divided into two chambers: an upper oil chamber 4A and a lower oil chamber 4B.

The upper end of the outer cylinder 13 is hermetically supported by the hanging part of the packing cap 7 which holds the rod guide 9.

The packing cap 7 has a sealing member 8 between the packing cap 7 and the rod guide 9.

The seal member 8 is tightly fitted to the piston rod 3 on the inner circumferential side and to the packing cap 7 on the outer circumferential side to seal the inside of the shock absorber.

A rod guide 9, which is disposed at a predetermined distance from the seal member 8 in the shock absorber, has an annular recess 9A and an end surface of the rod guide 9 formed in the center thereof so as to protrude upward in the axial direction. The valve seat 9B has a truncated conical shape.

- 14 is an annular valve body made of an elastic body (such as rubber) having a thick wall portion 14A and a thinner valve portion 14B; The thin valve part 14B is integrally fixed to the inner peripheral side of the rod guide 9, that is, the cylindrical part 15A, by baking or other means, and the thin valve part 14B hangs downward to apply its own interference to the valve seat 9B of the rod guide 9 from the outside in the radial direction. It is pressed into contact with the valve part to form a valve part.

The valve seat 9B and the valve body 14 constitute a valve means.

The rod guide 9 has a through hole 9C in its center, which has a diameter somewhat larger than the diameter of the piston rod 3, and an annular recess 9A in its outer periphery. It has a notch 9D that communicates with the gas chamber 6A.

Further, the seal member 8 is in close contact with the piston rod 3, and is constantly pressed against the bottom of the packing cap 7 by a spring 16 interposed in a space 18 between the seal member 8 and the rod guide 9 via the core metal 15. This prevents the oil adhering to the piston rod 3 or the oil inside the piston rod 3 from leaking to the outside.

Note that the valve body 14 is connected to the upper part of the rod guide 9 and the seal member 8.
A space portion 17A through which the piston rod 3 directly passes through a space 18 formed between the lower part of the piston rod and a space portion 17B in which the spring 16 is accommodated and communicates with the upper part of the reservoir chamber 6 via a notch 9D. It is separated into two rooms.

Here, the through hole 9C, the space portion 17A, the space portion 17B,
The cutout portion 9D defines a passage that communicates the gas chamber 6A and the oil chamber 4A.

The throttle hole 5 bored in the lower part of the inner cylinder 4 provides resistance to the amount of flowing oil. It has a cross-sectional area that creates a throttling effect on the flow of oil.

The installation position thereof is not limited to the lower part of the inner cylinder 4, and may be, for example, between the lower end of the inner cylinder 4 and the inner wall of the bottom cap 12.

Further, the spring force of the disk valve 10 provided on the piston 11 in the contraction direction is caused by the gas pressure in the gas chamber 6A of the reservoir chamber 6 and the throttling effect of the throttle hole 5 when the piston 11 moves in the contraction direction. Oil chamber 4A in relation to
The size is such that it maintains a positive pressure.

A washer 19, which is clamped and supported between the seal member 8 and the packing cap 7, is used when filling compressed gas into this shock absorber.

The present invention has the structure as described in detail above, and its operation will be described below.

First, the operation of the contraction stroke of the hydraulic shock absorber will be explained.

The piston 11-piston rod 3 assembly is connected to the inner cylinder 4
When the oil in the oil chamber 4B is pressurized, the oil in the oil chamber 4B flows out into the oil chamber 6B in the reservoir chamber 6 through the throttle hole 5 and the elastic force of the disc valve 10. That is, the outer peripheral edge of the disc valve 10 is bent upward against the spring force, causing a flow to flow into the oil chamber 4A, and at this time, a damping force is generated.

Further, the oil increased by the piston rod 3 entering the inner cylinder 4 flows into the reservoir chamber 6 through the throttle hole 5.

Even if the pressure of the compressed gas above the reservoir chamber 6 increases by the volume of oil entering and moves into the space 18 through the notch 9D,
In the space 18, the valve portion 14B of the valve body 14 is seated on the valve seat 9B, blocking the flow of compressed gas from the space 18 to the space portion 17A, the passage 9C, and the inner cylinder 4. The compressed gas that has moved to will not enter the inner cylinder 4.

Here, in conventional gas-filled hydraulic shock absorbers, this communication path (
In this case, the effective cross-sectional area of the throttle hole 5) is 4B below the piston.
There is no throttling effect between the piston 1 and the reservoir chamber 6, and the pressure change in the chamber below the piston as the piston descends.
The gas was designed to have a large cross-sectional area so that the gas could directly propagate to the gas chamber 6A over the entire speed range of 1.

Therefore, if the pressure in the gas chamber 6A does not reach a value sufficient to open the disc valve 10, negative pressure will be generated in the upper oil chamber 4A of the cylinder 4 during the piston's contraction stroke, resulting in a predetermined resistance force or damping. power cannot be secured.

Therefore, the pressure of the sealed gas in conventional hydraulic shock absorbers of this type that is commonly used is generally 20 atmospheres or more.

The use of such high pressure created harsh conditions for the manufacture and maintenance of the shock absorber, as well as for each component, but the hydraulic shock absorber of the present invention has a communication passage, that is, the throttle hole 5. The effective cross-sectional area of the oil chamber 4B is made small so as to cause a pressure drop between the oil chamber 4B and the reservoir chamber 6, thereby creating a throttling effect.

Therefore, in the high piston speed range, the throttling effect of the throttle hole 5 becomes large, and the pressure of the oil in the oil chamber 4B is not directly propagated into the reservoir chamber 6, and the pressure in the oil chamber 4B is throttled. It rises due to the throttling effect of hole 5, and [(piston 1
1 cross-sectional area - piston rod 3 cross-sectional area) x piston 11 movement amount] opens against the valve load of the disc valve 10, flows into the oil chamber 4A above the piston 11, and flows into the reservoir chamber 6. Only the excess oil due to the entry of the piston rod 3 flows out, and a predetermined resistance force can be generated without generating negative pressure in the oil chamber 4A.

However, if the lowering speed of the piston 11-piston rod 3 assembly is slow, the throttling effect of the throttle hole 5 will be reduced, and at this time most of the pressure in the oil chamber 4B will propagate into the reservoir chamber 6.

Therefore, if the gas pressure in the gas chamber 6A of the reservoir chamber 6 is low, the pressure in the oil chamber 4B will not increase enough to open the disc valve 10 against the spring force, and the pressure in the oil chamber 4B will not increase enough to open the disc valve 10 against the spring force. The oil will not flow out properly.

As a result, the flow rate that should flow from the oil chamber 4B into the oil chamber 6 through the throttle hole 5 becomes larger than the flow rate that originally flows out (piston rod cross-sectional area x piston rod movement distance).
Negative pressure is generated within A, making it impossible to secure the specified resistance force.

Therefore, in order to prevent this phenomenon, when the piston speed is slow, gas pressure is required in the gas chamber 6A to pressurize the oil chamber 4B so that the disc valve 10 can open against the valve load.

Since this required gas pressure is necessary only in the low speed range of the piston, it is sufficient that it is much lower than the conventional gas pressure, for example, 5 atmospheres is sufficient.

In the present invention, the gas pressure of the gas sealed in the gas chamber 6A in the reservoir chamber 6 has the effect of opening the disc valve 10 against the valve load only in the low piston speed range. In the piston high-speed range, the throttling effect of the throttle hole 5 that communicates the oil chamber 4B and the oil chamber 6B below the piston acts greatly to prevent the negative pressure from occurring in the oil chamber 4A. This prevents the generation of pressure.

Next, the operation of the hydraulic shock absorber in the extension direction will be explained.

The piston 11-piston rod 3 assembly is connected to the inner cylinder 4
When the piston 11 moves upward, the oil above the piston 11 bends the inner peripheral edge of the disc valve 10 downward, forming a flow path or flowing into the oil chamber 4B below it.

At this time, a damping force is generated.

Also, as the piston rod 3 moves out of the inner cylinder 4, the volume of oil in the oil chamber 6B flows through the throttle hole 5 to the oil chamber 4B.
By flowing into the interior, the volume compensation is threatened.

On the other hand, the gas that has entered the inner cylinder mixes with the oil that adheres to the surface of the piston rod 3 when the piston rod is extended, passes through the through hole 9C, is scraped off by the seal member 8, and is removed from the rod guide 9 and seal member 8. , and accumulates in the space 17A defined by the valve body 14.

The oil liquid containing gas in the space portion 17A is transferred to the piston 11-
During the next upward stroke of the piston rod 3 assembly, it is discharged into the space 17B.

That is, due to the pressure increase in the oil chamber 4A, a radially outward force is generated on the valve portion 14B of the valve body 14, and this force causes the vicinity of the boundary between the thick wall portion 14A and the valve portion 14B of the valve body 14 to The tip of the valve portion 14B bends radially outward with the bending center at , and is separated from the valve seat 9B, and the oil in the space portion 17A flows into the recess 9A.

Thereafter, when this force is released, the valve portion 14B acts as a one-way valve that is brought into contact with the valve seat 9B due to its own elasticity.

Here, the valve body extends in the axial direction between the rod guide and the sealing member, and the valve part is movable in the radial direction, so the pressure receiving area that contributes to opening the valve body extends from the rod guide abutting part to the center of bending. The distance is multiplied by the inner circumference of the valve portion, resulting in a wide area, resulting in extremely good valve opening responsiveness.

Furthermore, since the sealed gas pressure is extremely low, the pressure acting on the valve body 14 from the reservoir chamber side is also small, which prevents abnormal deformation of the valve body (such as wilting) and improves the responsiveness of the valve. .

Further, the valve body 14 is supported in contact with the lower part of the seal member 8 by a spring 16 interposed between the annular recess 9A and the lower surface of the core metal 15.

In this case, the core metal 15 has a tapered flange portion 1
The outer side of 5B is fitted into the inner side of the packing cap 7, and is positioned between the cap 7 and the seal member 8.

This positions the valve body 14.

In the embodiment, the mounting portion of the valve body 14 was placed in contact with the lower end of the seal member 8, but the installation position of the valve body 14 is not limited to this position. For example, the mounting portion may be placed on the rod guide side. Alternatively, the valve portion may be positioned on the sealing member 8 side.

In the figure, an example is shown in which the thick part 14A of the valve body 14 is fixed only to the cylindrical part 15A of the core bar 15, but in order to increase the rigidity of the one-way valve, the thick part 14A of the valve body 14 is integrally attached to the core bar 14. 1
Any structure can be used as long as it fixes the thick part 14 to the flange part 15B.
A may be extended.

The space 18 is separated into a space portion 17A and a space portion 17B by a valve body 14 that contacts the valve seat 9B of the rod guide 9 from the outside in the radial direction and acts as a one-way valve in the radially outward direction. .

Furthermore, in this embodiment, the valve body 14 is separate from the seal member 8, but they may be integrated with each other, and even when the mounting portion is located on the rod guide side as described above, the core can be removed. It would be good to set aside money.

In this embodiment, the damping force generation mechanism is a disc valve, but the present invention is not limited to this, and it is of course possible to use other damping force generation mechanisms such as an orifice or other valve. It is about.

Since the present invention has the structure as described in detail above, by appropriately setting the effective cross-sectional area of the throttle hole, the pressure of the filled gas, etc., it is possible to ensure a predetermined resistance force without generating negative pressure in the oil chamber 4A. may occur.

In addition, if the piston part has a damping force generating mechanism that operates in both directions, and the effective cross-sectional area of the throttle hole is set small, the gas pressure accommodated in the upper part of the reservoir chamber can be kept at an extremely low pressure.
High gas pressure does not act on the valve means and seals in the hydraulic shock absorber, improving the responsiveness of the valve means, reducing the amount of wear on the seals, and extending the life of the seals.As a result, the internal airtightness and liquidtightness can be maintained for a long time. This brings about a number of advantages, including:

Furthermore, since the valve part of the valve stage is arranged to extend in the axial direction between the rod guide and the sealing member, the pressure receiving area that contributes to valve opening is large, and the response of valve opening can be further improved. .

Furthermore, in the shock absorber of the present invention, since the core metal is integrally fixed to the valve body, the rigidity of the valve part of the one-way valve is increased, and even if the pressure in the reservoir chamber rises abnormally, the one-way valve can be completely prevented. It can fulfill its function.

In addition, the outer periphery of the core metal is fitted and supported by the inner surface of the packing cap to ensure positioning of the valve body, and the valve portion of the valve body can be reliably and uniformly seated on the valve seat. It becomes possible.

Furthermore, since the sealing member and the valve body are separate bodies, both can be made from the optimal materials for each, allowing the valve to fully function as a one-way valve.

Furthermore, since the sealing member and the valve body are separate members,
Since the movement of the seal member accompanying the movement of the piston rod does not directly act on the valve body, it is possible to obtain a stable function as a one-way valve.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of the hydraulic shock absorber of the present invention, and FIG. 2 is a partially enlarged sectional view of FIG. 3: Piston rod, 4: Inner cylinder, 4A: Oil chamber, 4B: Oil chamber, 5: Throttle hole, 6: Reservoir chamber, 6A: Gas chamber, 6B
: Oil chamber, 8: Seal member, 9: Rod guide, 9A: Annular recess, 9B: Valve seat, 9C: Through hole, 9D: Notch, 1
0: Disc valve, 11: Piston, 13: Outer cylinder, 1
4: Valve body, 15: Core metal, 16: Spring, 17A, 17B:
Spatial part, 18: Space.

Claims (7)

[Scope of utility model registration request] (1) Oil is stored in the lower part between the inner cylinder filled with oil and the inner cylinder loosely fitted outside the inner cylinder, and gas with a pressure exceeding atmospheric pressure is always stored in the upper part. an outer cylinder forming a reservoir chamber; a piston that is slidably provided within the inner cylinder and defines the interior into two upper and lower chambers; one end is fixed to the piston and the other end is a rod guide and a piston; A piston rod that penetrates a sealing member that seals the inside and outside of the shock absorber and slidably projects from the inside of the inner cylinder to the outside, and an oil liquid portion in a lower piston chamber in the inner cylinder and a lower part of the reservoir chamber. A gas portion of the reservoir chamber is formed between the rod guide and the piston rod, and the gas portion of the reservoir chamber is formed between the rod guide and the piston rod. a passageway that communicates with a chamber above the piston in the inner cylinder through an annular gap, and a valve located within the passageway that allows flow only from the chamber side above the piston to the reservoir chamber side. The body is provided with a valve body having a thick inner base and a valve part, and is provided on the piston, and when the piston moves in the contraction direction, positive pressure is applied to the chamber above the piston by the gas pressure and the throttle effect of the throttle hole. It consists of a damping force generation mechanism that maintains the
The valve body is disposed in a space forming a part of the passage and between the rod guide and the seal member, which are disposed apart from each other in the axial direction, without contacting the piston rod. Yes, and the valve body extends in the axial direction,
It is movable in the radial direction, so that the valve body contacts the fixed annular valve seat from the outside in the radial direction of the piston rod, blocking the flow of gas and liquid, and only when it moves radially outward, the air is released. A hydraulic shock absorber characterized by comprising a check valve that allows liquid to flow. (2) Utility model registration claim (1) characterized in that the base of the valve body is provided on the sealing member side, and the valve part is configured to take off and sit on a valve seat formed on the end face of the rod guide. Hydraulic shock absorber described in ). (3) The hydraulic shock absorber according to claim (2), wherein the base of the valve body is integrally formed with the seal member. (4) The hydraulic shock absorber according to claim (2), wherein the base of the valve body is constructed separately from the seal member. (5) The scope of the utility model registration claim, characterized in that the base of the valve body is provided on the rod guide side, and the valve portion is configured to take off and sit on a valve seat provided on the sealing member side. 1
Hydraulic shock absorber described in ). (6) Utility model registration claim (2) or (5) characterized in that the valve body is integrally fixed to a core metal.
Hydraulic shock absorber as described in section. (7) The hydraulic shock absorber according to claim (6), wherein the core metal receives one end of a spring disposed between the rod guide and the seal member.