JPH0538433U - Hydraulic shock absorber - Google Patents

Abstract

(57) [Summary] [Object] To provide a hydraulic shock absorber capable of obtaining a stable sealing function while simplifying a sealing structure of a piston rod sliding portion. A hydraulic shock absorber in which a rod guide 6 slidably supporting a piston rod 5 is attached to the upper ends of cylinders 1 and 2, and an upper side of the rod guide 6 is covered with an oil seal 7, the oil seal 7 The check lip portion 18 provided on the lower side surface of the rod guide 6 is formed in a tongue-shaped cross-section that widens outward in the radial direction toward the tip so that the tip portion abuts the bottom surface 11a of the annular recess 11 provided in the rod guide 6. The elastic piece 18a and the reinforcing ribs 11b formed in at least two locations at intervals on the outer or inner sides of the curved elastic piece 11a and extending in the vertical direction.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a hydraulic shock absorber used in combination with a coil spring in, for example, an automobile suspension.

[0002]

[Prior Art]

 Conventionally, as this type of hydraulic shock absorber, there is one disclosed in Japanese Utility Model Laid-Open No. 2-87147. In this hydraulic shock absorber, a rod guide that slidably supports a piston rod is attached to an upper end portion of an outer cylinder, and an upper side of the rod guide is covered with an oil seal. This oil seal is provided on the inner peripheral part of the disc-shaped metal reinforcing ring part whose outer peripheral part is pressure-contacted to the throttle part of the outer cylinder in an airtight state, and the piston rod is in an airtight state. The inner peripheral seal lip part that slidably abuts on the inner peripheral part, the dust lip part provided on the inner peripheral part of the reinforcing ring part to prevent dust from entering above the inner peripheral seal lip part, and the lower part of the reinforcing ring. A check lip portion is provided on a side surface and is in contact with a bottom surface of an annular recess formed on the upper side surface of the rod guide. The space between the oil seal and the rod guide is divided into two spaces, the inner space and the outer space, by the check lip portion, and the inner space space passes through the gap between the rod guide and the piston rod and becomes The outer space portion is communicated with the reservoir chamber between the inner cylinder cylinder and the outer cylinder cylinder through a communication hole formed in the rod guide. Then, the bottom surface of the annular recess provided in the rod guide and the check lip portion provided in the oil seal allow the buffer oil to flow back from the inner cylinder cylinder into the reservoir chamber, but prevent the compressed gas from flowing in the opposite direction. A one-way valve that does not allow is configured. In other words, the piston rod and the piston fixed to it move downward, the lower cylinder chamber in the inner cylinder cylinder chamber is compressed and the buffer oil is pushed out, and this buffer oil causes the lower end of the outer cylinder cylinder and the valve provided on the piston. When they flow into the reservoir chamber and the upper cylinder chamber respectively (during shock absorption of the hydraulic shock absorber), the compressed gas filled in the reservoir chamber further increases in pressure, but the compressed gas filled in the rod guide does not hit the bottom surface of the annular recess provided in the rod guide. The compressed gas does not flow into the inner space portion through the outer space portion between the oil seal and the rod guide because the compressed gas is blocked by the check lip portion provided in the contacting oil seal. However, contrary to the above, when the piston rod and piston move upward and the upper cylinder chamber inside the inner cylinder chamber is compressed and the buffer oil is pushed out, this buffer oil is generated between the rod guide and the piston rod. Gap, the inner space between the oil seal and the rod guide, flows into the outer space without being hindered by the check lip, and returns to the reservoir chamber through the communication hole provided in the rod guide. It is supposed to do. In order to obtain such a function of the one-way valve, the check lip portion is radially outward as the tip end abuts the bottom surface of the annular recess provided in the rod guide and goes to the tip side where the whole is curved. It is formed into an elastic piece with a tongue-shaped cross-section.

[0003]

[Problems to be solved by the device]

 However, in the conventional hydraulic shock absorber described above, when a high-pressure back pressure acts on the check lip portion from the compressed gas in the reservoir chamber, the tip portion of the check lip portion may be pressed and held at a fixed position on the bottom surface of the annular recess. There is a risk that the check lip will deform and the tip will slide inward in the radial direction while being pressed against the bottom of the annular recess, and eventually the tip of the check lip will reverse and fall off the bottom of the annular recess. is there . If the tip of the check lip falls out of the annular recess, the backflow prevention function will not work, and the compressed gas in the reservoir chamber will flow back into the upper cylinder chamber, impairing the damping characteristics of the hydraulic shock absorber. It is necessary to improve the bending rigidity so that the will not reverse.

Therefore, it is conceivable to increase the thickness of the check lip portion, but according to this method, it is possible to prevent the compressed gas in the reservoir chamber from flowing back into the upper cylinder chamber, but the valve opening pressure is increased. Inevitably, the buffer oil cannot be smoothly returned from the inner cylinder to the reservoir chamber.

The present invention has been made to solve the above problems, and provides a hydraulic shock absorber capable of obtaining a stable sealing function while simplifying the sealing structure of the piston rod sliding portion. With the goal.

[0006]

[Means for Solving the Problems]

 This invention is a hydraulic shock absorber in which a rod guide that slidably supports a piston rod is attached to the upper end of a cylinder, and the upper side of the rod guide is covered with an oil seal. The lip has a tongue-shaped elastic piece whose cross-sectional shape spreads outward in the radial direction toward the tip so that the tip comes into contact with the bottom surface of the annular recess provided in the rod guide. It is composed of at least two reinforcing ribs formed in an outer or inner circumferential direction and spaced apart from each other in the circumferential direction.

[0007]

[Action]

 The bending rigidity of the elastic piece is increased where the reinforcing rib is provided. In this way, the elastic piece curved in the circumferential direction, which has the elastic piece with improved bending rigidity integrally on both sides, is less likely to be deformed inward in the radial direction. For this reason, when a high back pressure is applied to the check lip portion, the elastic piece is held in contact with a predetermined position on the bottom surface of the annular recess and is not reversed and dropped.

Further, when the pressure of the buffer oil acts on the check lip portion, the elastic piece between the reinforcing ribs bends to open between the tip portion of the check lip portion and the bottom surface of the annular recess.

[0009]

【Example】

 An embodiment of this invention will be described below with reference to FIGS.

The lower portion of the outer cylinder 1 is attached to a wheel (not shown) via a bracket 30, and the inner cylinder 2 is concentrically provided inside the outer cylinder 1 and A reservoir chamber 3 is formed between the cylinder chamber 2 and the cylinder 2. A piston (not shown) is slidably fitted in the inner cylinder cylinder 2, and the piston divides the inner cylinder cylinder 2 into an upper cylinder chamber 4 and a lower cylinder chamber (not shown). The piston is provided with a valve (not shown) that regulates the flow of the buffer oil from the lower cylinder chamber to the upper cylinder chamber 4.

The piston rod 5, to which the piston is fixed, extends above the outer cylinder 1 and is attached to a vehicle body (not shown) via a threaded portion 5 a formed at the upper end, and is not shown in the piston rod 5. The upper retainer is installed.

A bottom plate (not shown) that seals the outer cylinder 1 is attached to the lower end of the outer cylinder 1. Inside the bottom plate, a space between the reservoir chamber 3 and the inner cylinder cylinder 2 is provided. A bottom valve (not shown) that regulates the flow of the buffer oil is provided. A lower retainer 31 is attached to the outside of the outer cylinder 1.

A spring (not shown) is compressed between the upper retainer provided on the piston rod 5 and the lower retainer 31 provided on the outer cylinder 1.

A rod guide 6 that slidably supports the piston rod 5 is attached to the upper end of the outer cylinder 1, and an upper side of the rod guide 6 is covered with an oil seal 7.

The rod guide 6 has a body portion 8 that is press-fitted into the upper end portion of the outer cylinder 1, and the lower side surface of the body portion 8 is press-fitted into the upper end portion of the inner cylinder cylinder 2 and the outer cylinder. A press-fitting portion 9 for positioning and fixing the same with respect to the cylinder 1 is formed, a first annular recess 10 and a second annular recess 11 are formed concentrically with the body portion 8 on the upper side surface, and the second annular ring is provided on the side portion. A communication hole 12 that connects the inside of the recess 11 and the inside of the reservoir chamber 3 is formed. A guide bush 13 that slidably supports the piston rod 5 is attached to the inner peripheral portion of the rod guide 6.

The oil seal 7 is provided at the center of the disk-shaped metal reinforcing ring portion 14 and the inner peripheral portion of the reinforcing ring portion 14 and is slidably attached to the piston rod 5 in an airtight state. The inner peripheral seal lip portion 15 in contact with the reinforcing annular portion 14, the dust lip portion 16 provided on the inner peripheral portion of the reinforcing annular portion 14 to prevent dust from entering above the inner peripheral seal lip portion 15, and the outer periphery of the reinforcing annular portion 14. The outer cylinder so that the outer cylinder can be kept airtight when the outer circumference is pressed against the entire circumference of the throttle 1a formed by bending the upper end of the outer cylinder 1 toward the inner circumference. The cylinder 1 is provided with an outer peripheral seal lip portion 17 that is pressed against the inner surface of the upper end portion, and an annular check clip portion 18 that is provided on the lower side surface of the reinforcing ring 14 and that restricts the flow of buffer oil.

The inner peripheral seal lip portion 15 and the check lip portion 18 provided in the oil seal 7 are inserted into the first annular recess 10 and the second annular recess 11 provided in the rod guide 6, respectively.

The check lip portion 18 has an elastic piece formed in a tongue-shaped cross-section that widens radially outward toward the tip so that the tip portion abuts the bottom surface 11 a of the second annular recess 11 provided in the rod guide 6. 18a and reinforcing ribs 18b formed along the vertical direction at four locations on the outer side (FIGS. 1 and 2) or the inner side (FIGS. 3 and 4) of the elastic piece 18a at intervals in the circumferential direction. Has been done. The tip of the elastic piece 18a is in contact with the bottom surface 11a of the second annular recess 11 provided in the rod guide 6.

The space between the rod guide 6 and the oil seal 7 is divided into two space portions 19 and 20 inside and outside by the check lip portion 18. The inner space portion 19 communicates with the inside of the inner cylinder 2 through a gap between the piston rod 5 and the rod guide 6 (guide bush 13). Further, the outer space portion 20 communicates with the inside of the reservoir chamber 3 between the outer cylinder cylinder 1 and the inner cylinder cylinder 2 through a communication hole portion 12 provided in the rod guide 6.

The bottom 11a of the second annular recess 11 provided on the rod guide 6 and the check lip 18 provided on the oil seal 7 allow the buffer oil to flow back from the inner cylinder 2 into the reservoir chamber 3. The one-way valve A is configured to permit the flow of compressed gas in the opposite direction but not permit the flow of compressed gas in the reverse direction.

In such a hydraulic shock absorber, the elastic force of the spring compressed between the upper retainer on the piston rod 5 side and the lower retainer 31 on the outer cylinder 1 side causes the elastic force to the cylinders 1 and 2. When the piston rod 5 is lifted and the distance between the vehicle body and the wheel is kept constant, and when an impact is applied from the wheel side to the vehicle body side, the cylinders 1 and 2 move upward with respect to the piston rod 5 and the piston. , The lower cylinder chamber in the inner cylinder cylinder 2 is compressed and the buffer oil is pushed out, and this buffer oil passes through the lower end portion of the outer cylinder cylinder 1 and the valve provided in the piston, and the inside of the reservoir chamber 3 and the upper cylinder chamber 4 respectively. The shock is buffered by flowing into the inside.

During this shock buffering, the compressed gas filled in the reservoir chamber 3 is further increased in pressure, and passes through the communication hole 12 provided in the rod guide 6 and the outer space 20 between the rod guide 6 and the oil seal 7. Although a high back pressure acts on the check lip portion 18, the elastic piece 18a between the reinforcing ribs 18b and 18b has elastic pieces 18a whose bending rigidity is improved by the reinforcing ribs 18b integrally on both sides in the circumferential direction. The elastic piece 18a contacts the predetermined position of the bottom surface 11a of the second annular recess 11 even if a high back pressure is applied to the check lip portion 18, because it is curved inward and is hard to be deformed inward in the radial direction. It is held in close contact and will not fall out. Therefore, the high-pressure compressed gas is not blocked by the check lip portion 18 and flows into the inner space portion 19 between the rod guide 6 and the oil seal 7.

Further, at the time of returning after shock buffering, contrary to the above, the cylinders 1 and 2 move downward with respect to the piston rod 5 and the piston, the upper cylinder chamber 4 is compressed, and the buffer oil is pushed out. This buffer oil flows into the inner space portion 19 between the rod guide 6 and the oil seal 7 through the gap between the piston rod 5 and the rod guide 6 (guide bush 13), and the pressure of the buffer oil is reduced by the check lip portion 18. Act on. The elastic piece 18a between the reinforcing ribs 18b and 18b is elastically deformed so as to be separated from the bottom surface 11a of the second annular concave portion 11 under the pressure of the buffer oil, and the tip of the check lip portion 18 and the second annular concave portion 11 are separated. The space between the bottom surface 11a is opened. Therefore, the buffer oil flows into the outer space portion 20 between the rod guide 6 and the oil seal 7 without being hindered by the check lip portion 18, passes through the communication hole portion 12 provided in the rod guide 6, and becomes the reservoir. Reflux into chamber 3.

In the one-way valve A as described above, since the check lip portion 18 is in contact with the large-width bottom surface 11 a of the second annular recess 11, the check lip portion 18 is stable regardless of the radial accuracy. On-off valve pressure can be obtained.

In the embodiment, the elastic pieces 18a forming the annular check lip portion 18 provided on the lower surface of the oil seal 7 are circumferentially spaced on the outer side or the inner side of the elastic piece 18a. Although the reinforcing ribs 18b are formed, it is needless to say that the reinforcing ribs 18b are formed at least at two positions at intervals in the outer or inner circumferential direction of the elastic piece 18a and are not limited to four positions.

[0026]

[Effect of the device]

 As described above, according to this invention, the check lip portion provided on the lower surface of the oil seal spreads outward in the radial direction toward the tip end so that the tip end contacts the bottom surface of the annular recess provided in the rod guide. The elastic piece having a tongue-shaped cross-section and the reinforcing ribs formed in at least two locations at intervals in the outer or inner circumferential direction of the curved elastic piece and extending in the vertical direction are provided. Since the elasticity of the check lip part in the is maintained, it is not necessary to raise the valve opening pressure. In addition, the reinforcing ribs can prevent the tip of the check lip from reversing from the outer space between the rod guide and the oil seal to the inner space and dropping off from the bottom of the annular recess. The air will not flow back into the cylinder chamber and the damping characteristics of the hydraulic shock absorber will not be impaired. Therefore, while further simplifying the sealing structure of the piston rod sliding portion in the hydraulic shock absorber, a more stable sealing function can be obtained.

[Brief description of drawings]

FIG. 1 is a side view showing an entire embodiment of the present invention with a main part being a cross section.

FIG. 2 is an enlarged sectional view of a main part of FIG.

FIG. 3 is an enlarged view of the oil seal in FIG.
It is sectional drawing which follows the line.

FIG. 4 is a bottom view of FIG.

FIG. 5 is a side sectional view showing an essential part of another embodiment of the present invention.

6 is an enlarged view of the oil seal in FIG. 5, 6-6 in FIG.
It is sectional drawing which follows the line.

FIG. 7 is a bottom view of FIG.

[Explanation of symbols]

 1 Outer cylinder cylinder 2 Inner cylinder cylinder 3 Reservoir chamber 5 Piston rod 6 Rod guide 7 Oil seal 11 Second annular recess 11a Bottom 18 Check lip 18a Elastic piece 18b Reinforcing rib 19 Inner space 20 Outer space A One-way valve

Claims (1)

[Scope of utility model registration request] 1. A hydraulic shock absorber in which a rod guide slidably supporting a piston rod is attached to an upper end portion of a cylinder, and an upper side of the rod guide is covered with an oil seal, the hydraulic shock absorber being provided on a lower side surface of the oil seal. An elastic piece having a tongue-shaped cross section that spreads outward in the radial direction toward the tip side so that the tip end portion contacts the bottom surface of the annular recess provided in the rod guide, and the curved elastic piece. And a reinforcing rib extending in the up-and-down direction at least at two positions spaced apart in the outer or inner circumferential direction of the hydraulic shock absorber.