JPH0519623Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a hydraulic shock absorber used in automobile suspension systems and the like.

BACKGROUND ART Conventionally known hydraulic shock absorbers include, for example, as disclosed in Japanese Patent Application Laid-open No. 156739/1983.
An annular seal ring that fits around the outer periphery of the piston rod is movably accommodated in a ring groove provided on the inner circumference of the guide member that guides the insertion and removal movement of the piston rod, so that the piston rod moves downward (inward of the cylinder). When the seal ring is positioned below the ring groove and the lower surfaces of the seal ring and the ring groove are in contact with each other, the cylinder and the outer cylinder arranged concentrically around the outer circumference of the cylinder are connected. This prevents the sealed gas in the reservoir chamber formed between the cylinders from leaking into the cylinder, and when the piston rod moves upward, the seal ring is positioned above the ring groove, and the contact surface between the seal ring and the ring groove is A portion of the hydraulic fluid in the cylinder is guided to the upper side of the guide member through the groove formed in the guide member, thereby lubricating the seal member disposed there. A concave oil reservoir facing the seal member is provided at the upper part (axially outward) of the guide member, and the ring groove is located between this oil reservoir and the upper chamber of the cylinder. It is provided in the middle of the gap between the guide part and the piston rod. Therefore, the liquid and gas that have flowed into the upper part of the guide member are separated into gas and liquid in the oil reservoir, making it difficult for gas to enter the ring groove.

Problems to be solved by the invention However, in the case of such conventional examples,
Since the seal ring is made of resin material,
With long-term use, the contact surface with the ring groove wears out, and the cross-sectional area of the fine grooves decreases, or the grooves disappear, making it impossible to discharge the gas generated in the cylinder tube due to aeration, etc. As a result, gas remains in the cylinder tube, causing problems such as abnormal noises being generated during operation of the hydraulic shock absorber and failure to generate normal damping force.
In addition, it is difficult to precisely machine the minute grooves formed on the sliding contact surface of the seal ring, and it is also difficult to accurately machine the contact surface of the ring groove that is in close contact with the seal ring. Ta. Therefore, there has been a problem in that the damping force varies due to poor precision of these grooves and contact surfaces.

Therefore, the present invention aims to solve these problems of the prior art.

Means for Solving the Problems That is, the present invention includes a cylinder tube filled with a liquid, and a reservoir chamber disposed outside the cylinder tube and filled with gas and liquid between the cylinder tube and the cylinder tube. a reservoir tube; a piston rod that is removably inserted into the cylinder tube; a seal member that slides on the piston rod and seals between the piston rod and the reservoir tube; The piston rod is attached to the piston rod and supports the piston rod in a reciprocating manner, and has a concave oil reservoir portion facing the sealing member at an axially outer portion thereof, and a passage communicating the upper portion of the oil reservoir portion with the reservoir chamber. and a rod guide having a ring groove in a gap between the oil sump and the piston rod located between the oil reservoir and the upper chamber of the cylinder tube, and a rod guide that is loosely fitted into the ring groove and slidably fitted to the piston rod. In the hydraulic shock absorber, an orifice plate having an orifice groove that opens from the center side toward the outside in the radial direction is arranged in the ring groove adjacent to the outside in the axial direction of the seal ring. A spacer ring is disposed adjacent to the outer side of the orifice plate in the axial direction, and the spacer ring covers the outer circumferential side of the orifice groove of the orifice plate and forms a constant orifice with the inner circumference and the orifice groove. It is characterized by

Action When the pressure in the upper chamber of the cylinder tube increases more than the pressure in the reservoir chamber during the extension stroke of the piston rod, the seal ring, orifice plate, and spacer ring are pressed against one side of the ring groove, and the orifice groove of the orifice plate and the spacer ring are pressed against one side of the ring groove. A constant orifice is formed by the inner circumference of the ring.

Therefore, fluid in the upper chamber of the cylinder tube flows through this constant orifice into the reservoir chamber. Then, the flow of the fluid is throttled when passing through this constant orifice, and the amount of fluid flowing out is controlled.

On the other hand, during the compression stroke of the piston rod, if the pressure in the reservoir chamber becomes greater than the pressure in the upper chamber of the cylinder tube, the seal ring, orifice plate, and spacer ring are pressed against the other side of the ring groove, causing a gap between the reservoir chamber and the cylinder tube. Communication with the upper chamber is cut off. Further, the rod guide is provided with a concave oil reservoir facing the sealing member and a passage communicating the upper part of the oil reservoir with the reservoir chamber, and a ring groove is provided between the oil reservoir and the upper chamber of the cylinder tube. Because of this, the gas that flows into the upper part of the rod guide from the reservoir chamber through the passage is vertically separated from the liquid in the oil reservoir chamber, and this gas does not enter the ring groove.

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

FIG. 1 is a sectional view of a main part of a hydraulic shock absorber showing an embodiment of the present invention. In the figure, 1 is a cylinder tube filled with liquid. A reservoir tube 2 is arranged concentrically outside the cylinder tube 1. A reservoir chamber 3 is formed between the reservoir tube 2 and the cylinder tube 1, and gas and liquid are stored inside the reservoir chamber 3. is filled with. 4 is a piston rod, and this piston rod 4 is inserted and inserted into the cylinder tube 1 so as to be freely inserted and removed, and a piston (not shown) that reciprocates within the cylinder tube 1 is fixed to the tip.
It is supported by a rod guide 5 at the open end of the cylinder tube 1 so as to be able to reciprocate and slide. The rod guide 5 is fitted inside the reservoir tube 2, and has a three-stage recess 6 that opens upward in the figure. The three-stage recess 6 of this rod guide 5 consists of a large diameter recess 7, a medium diameter recess 8, and a small diameter recess 9.
Inside the large-diameter recess 7 is an annular space 1 serving as an oil storage chamber.
0 is formed in the medium diameter recess 8, and a fixing member 12 that closes the open end of the small diameter recess 9 to form a ring groove 11.
are fitted and fixed. A seal ring 13 is housed inside the ring groove 11 and is fitted with gaps in the axial and radial directions with respect to the ring groove 11 and is slidably fitted on the piston rod 4. There is. Further, on the axially outer side of the seal ring 13 in this ring groove 11, as shown in FIG. A constant orifice 16 is disposed adjacent to the orifice plate 15 and is made of a high hardness material and is in contact with the orifice plate 15 and forms a constant orifice 16 between the inner circumference of the orifice plate 15 and the orifice groove 14. A spacer ring 17 is provided. And these seal rings 1
3. The movement of the orifice plate 15 and the spacer ring 17 in the axial direction is performed using the side surface 1 of the ring groove 11.
8 and the side surface 19 of the fixing member 12. Reference numeral 20 denotes a sealing member disposed adjacent to the outside in the axial direction of the rod guide 5, and this sealing member 20
The outer periphery of the cylinder tube 1 is fitted into the reservoir tube 2, and the seal lip 21 is fitted onto the piston rod 4, and is caulked and fixed to the open end of the reservoir tube 2 together with the rod guide 5, thereby closing the open ends of the cylinder tube 1 and the reservoir tube 2. ing. Note that the annular space 10 serving as an oil reservoir is provided with a seal member 20.
It is provided so as to face the seal lip 21 of. 22 is a passage that communicates the reservoir chamber 3 and the annular space 10. Further, 23 is a gap between the fixed member 12 and the piston rod 4, and 24 is a gap between the bearing 5a of the rod guide 5 and the piston rod 4. The ring groove 11 is provided between the gaps 23 and 24 located between the annular space 10 and the upper chamber 1a of the cylinder tube 1.

According to the above embodiment structure, the piston rod 4
moves upward in the figure (during extension stroke), and the pressure in the upper chamber 1a becomes greater than the pressure in the reservoir chamber 3, the fluid in the upper chamber 1a passes through the gap 24 and enters the ring groove 11. Seal ring 1 leaked out
3. Press the orifice plate 15 and spacer ring 17 toward the fixing member 12. At this time, the spacer ring 17 is pinched between the orifice plate 15 and the fixing member 12, covers the outer peripheral side of the orifice groove 14 of the orifice plate 15, and forms a constant orifice 16 (see FIGS. 1 and 2). condition). Therefore, the fluid that has flowed into the ring groove 11 is transferred between the seal ring 13 and the ring groove 1.
1, the orifice groove 14, the constant orifice 16, and the gap 23, and flows into the annular space 10, and then passes through the passage 22 and flows into the reservoir chamber 3. In this manner, the flow rate of the fluid flowing out from the upper chamber 1a of the cylinder tube 1 into the reservoir chamber 3 is controlled by the constant orifice 16. By this,
The damping force of the hydraulic shock absorber becomes stable.

On the other hand, when the piston rod 4 moves downward in the figure (during the compression stroke), if the pressure in the reservoir chamber 3 becomes greater than the pressure in the upper chamber 1a, fluid flows from the reservoir chamber 3 side toward the upper chamber 1a side. The seal ring 13 is pressed against the side surface 18 of the ring groove 11. Therefore, the gap 24 is closed and the fluid in the reservoir chamber 3 is prevented from flowing into the upper chamber 1a. Note that when the piston rod 4 is in a stationary state, the gas in the reservoir chamber 3 flows into the passage 2.
2, but the rod guide 5 has a large diameter recess 7.
As a result, an annular space 10 is formed as an oil reservoir, and the passage 22 opens at the top of this annular space 10, so that liquid and gas are separated in the annular space 10, and after that, the piston rod 4 Gas does not flow into the ring groove 11 even when the compression stroke begins.

Effects of the invention As described above, in this invention, a constant orifice is formed by an orifice plate and a spacer ring that are separate from the seal ring, so the orifice plate and spacer ring are made of highly durable, high-hardness material. can be formed,
Furthermore, since a constant orifice is formed by the groove of the orifice plate that opens radially outward from the center side and the inner circumference of the spacer ring, if the orifice plate or spacer ring This has the effect that the area of the constant orifice does not change even if it is worn out over time.

In addition, the present invention provides the rod guide with a concave oil reservoir facing the sealing member and a passage communicating the upper part of the oil reservoir with the reservoir chamber, and between the oil reservoir and the upper chamber of the cylinder tube. Since a ring groove is provided for accommodating the seal ring in the oil sump, the fluid that flows from the reservoir chamber through the passage into the upper part of the rod guide is separated into gas and liquid in the oil sump. Gas will no longer flow into the ring groove located below.

Therefore, according to the present invention, without impairing the basic effect of reliably preventing gas from flowing into the upper chamber of the cylinder tube from the reservoir chamber, the constant orifice prevents gas generated in the upper chamber over time. to the reservoir chamber,
Moreover, the amount of fluid flowing out can be accurately controlled.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a main part of a hydraulic shock absorber showing an embodiment of the present invention, and FIG. 2 is a sectional view taken along line A--A in FIG. 1. 1... Cylinder tube, 2... Reservoir tube, 3... Reservoir chamber, 4... Piston rod, 5... Rod guide, 11... Ring groove, 1
3... Seal ring, 14... Orifice groove, 1
5... Orifice plate, 16... Constant orifice, 17... Spacer ring, 20...
...Seal member.

Claims (1)

[Scope of utility model registration request] a cylinder tube filled with liquid; a reservoir tube disposed outside the cylinder tube and defining a reservoir chamber filled with gas and liquid between the cylinder tube; A fitted piston rod, a sealing member that slides on the piston rod and seals between the piston rod and the reservoir tube, and a sealing member that is attached to straddle the open ends of the reservoir tube and the cylinder tube to support the piston rod in a reciprocating manner. and a concave oil sump portion facing the sealing member on an axially outer portion thereof, and a passage communicating the oil sump portion with the reservoir chamber, and between the oil sump portion and the upper chamber of the cylinder tube. A hydraulic shock absorber comprising: a rod guide having a ring groove in a gap between the rod guide and the piston rod; and a seal ring loosely fitted into the ring groove and slidably fitted to the piston rod. Inside the groove, an orifice plate having an orifice groove that opens radially outward from the center side is disposed adjacent to the axially outer side of the seal ring. A hydraulic shock absorber characterized in that a spacer ring is disposed adjacent to the axially outer side of an orifice plate to form a constant orifice with its inner circumferential portion and orifice groove.