JPH1054436A - Cylinder device - Google Patents

Abstract

(57) [Problem] To suppress an unnecessary increase in frictional resistance of a rod seal backed up by an O-ring. SOLUTION: A rod seal 18 for sealing a piston rod 3 extended from a piston in a cylinder is provided.
In the hydraulic cylinder in which the O-ring 19 disposed on the outer side of the cylinder is elastically urged against the piston rod 3, the stepped portion 4 is formed on the inner peripheral surface and the outer peripheral surface of the rod seal 18.
5 and 46 are provided, and the main body 30 and the lid 31 constituting the rod guide are provided with projections 47 and 48 which can be fitted to the step portions 45 and 46 respectively. When the pressure difference between the O-ring 19 and the O-ring 19 is strongly compressed and the urging force increases, the protrusion 4
7 and 48 share the urging force, and the rod seal 18
Is prevented from being pressed against the piston rod 3 by a strong force.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cylinder device mounted on a suspension system of an automobile.

[0002]

2. Description of the Related Art As a cylinder device mounted on a suspension system of an automobile, there are, for example, a hydraulic cylinder for adjusting a vehicle height and a hydraulic shock absorber for absorbing a shock.

FIG. 10 shows a hydraulic cylinder provided in a suspension control device for controlling a vehicle height. A piston 2 is slidably fitted in a cylinder 1 in which oil is filled, and a piston 2 The other end of the piston rod 3, one end of which is connected to the opening end of the cylinder 1, extends through the sealing means 4, which will be described later, in a liquid-tight manner and extends outside the cylinder 1. The cylinder 1 is housed in a bottomed outer cylinder 5, and the space between the two is closed by the sealing means 4 and provided as a drain chamber (annular chamber) 6. The piston 2 is provided with an oil passage 7 communicating the upper and lower chambers in the cylinder 1 and a disk valve 8 for controlling the flow of the oil liquid in the oil passage 7 to generate a damping force. On the other hand, an oil passage 9 for supplying / discharging the oil liquid to / from the cylinder 1 is provided in the piston rod 3, and the other end of the piston rod 3 is provided with a supply / discharge means 11 through a pipe joint 10, An accumulator 12 as a component and a damping force adjusting valve 13 as a damping component are connected. Reference numeral 14 denotes a protective cover fitted and fixed to the piston rod 3 at a position outside the cylinder 1.

In such a hydraulic cylinder, the length of the piston rod 3 is changed by supplying / discharging the oil liquid to / from the cylinder 1 through the oil passage 9 by the oil supply / drainage means 11, thereby adjusting the vehicle height. Further, the damping force is adjusted by changing the flow resistance of the oil liquid between the cylinder 1 and the accumulator 11 due to the expansion and contraction of the piston rod 3 by the damping force adjusting valve 13.

[0005] Incidentally, the above-mentioned sealing means 4 is conventionally used in FIG.
As shown in FIGS. 1 and 12, a rod guide 15 fitted to the cylinder 1 and the outer cylinder 5 to slidably guide the piston rod 3 and the rod guide 15 screwed to the outer cylinder 5 are provided.
And a lock block 16 for holding the lock block 16 from above. The rod guide 15 holds a double seal 20 including a rod seal 18 that slides on the piston rod 3 and an O-ring 19 that urges (backs up) the rod seal 18 toward the piston rod 3. The lock ring 16 holds an oil seal 21.

The rod seal 1 constituting the double seal 20
8 is made of a material having an excellent sliding performance with emphasis on sliding characteristics.
A slight oil leak occurs in accordance with an increase in the hydraulic pressure in the cylinder inner chamber 1a. On the other hand, the oil seal 21
Is formed of rubber having a good sealing property, and the oil liquid (leakage oil) leaked from between the rod seal 18 and the piston rod 2 is prevented from leaking outside by the oil seal 21. The oil liquid, which has been prevented from leaking to the outside, once accumulates in an oil sump chamber 22 formed between the double seal 20 and the oil seal 21 and then is returned to the rod guide 1.
5 is evacuated to the drain chamber 6 through an oil passage 23 provided in the drain chamber 5.

[0007]

However, in the above-mentioned conventional hydraulic cylinder, when the oil pressure in the cylinder inner chamber 1a rises above a certain value, the pressure difference ΔP from the oil reservoir chamber 22 causes
The O-ring 19 is pushed upward to be strongly compressed, and presses the rod seal 18 against the piston rod 3 with a strong force. As a result, the frictional resistance of the rod seal 18 increases,
The smooth expansion and contraction of the piston rod 3 is hindered, resulting in a deterioration in riding comfort. In addition, there is a problem that the wear of the rod seal 18 increases and oil leakage becomes severe. In addition,
Also in the hydraulic shock absorber, the rod seal 18 and the O
In many cases, a double seal 20 with the ring 19 is employed, and the same problem also occurs with this seal. However, in the case of a hydraulic shock absorber, the annular chamber 6 around the cylinder 1 is provided as a reservoir.

The present invention has been made in view of the above-mentioned conventional problems, and an object thereof is to suppress an unnecessary increase in the frictional resistance of a rod seal backed up by an O-ring. is there.

[0009]

According to the first aspect of the present invention, a piston is slidably fitted in a cylinder in which oil is sealed, and one end of the piston is fitted to the piston. The other end of the connected piston rod is inserted through a seal block attached to the open end of the cylinder, extends to the outside of the cylinder, and the piston is inserted into an annular groove provided on the piston rod side of the seal block. In a cylinder device holding a double seal composed of a rod seal slidably in contact with a rod and an O-ring for resiliently urging the rod seal toward the piston rod, a seal receiving surface on the outer side of the cylinder in the axial direction of the annular groove is provided. A projection is provided between the O-ring and the rod seal to receive a part of the urging force applied to the rod seal from the O-ring. To.

According to the cylinder device of the first aspect, when a large hydraulic pressure is applied to the O-ring and a large urging force is applied to the rod seal, the projection provided in the annular groove of the seal block is provided with the projection. Sharing the power, the rod seal is no longer pressed strongly against the piston rod.

According to a second aspect of the present invention, a piston is slidably fitted in a cylinder in which an oil liquid is sealed, and the other end of a piston rod having one end connected to the piston is connected to the piston. The seal block attached to the open end of the cylinder is inserted and extended to the outside of the cylinder, and in the annular groove provided on the piston rod side of the seal block,
In a cylinder device holding a double seal composed of a rod seal that slides on a piston rod and an O-ring that elastically urges the rod seal toward the piston rod,
A ring-shaped seal cover having an inner peripheral surface substantially slidably contacting the piston rod is provided between an end surface of the double seal outside the axial cylinder and an end surface of the annular groove outside the axial cylinder. , The piston cover is disposed so as to be movable in the radial direction of the piston rod, and the O-ring is provided between the O-ring and the rod seal on the seal receiving surface of the seal cover.
A projection for receiving a part of the urging force applied to the rod seal from the ring is provided.

According to the second aspect of the present invention, when a large hydraulic pressure is applied to the O-ring and a large urging force is applied to the rod seal, the projection provided on the seal cover shares the urging force. As in the case of the first aspect, the rod seal is not strongly pressed against the piston rod. In addition, since the seal cover is almost slidably in contact with the piston rod and is arranged so as to be movable in the radial direction of the piston rod, the rod seal does not bite into the gap between the piston rod and the seal block. Also, smooth expansion and contraction of the piston rod is guaranteed.

Further, according to the third aspect of the present invention, a piston is slidably fitted in a cylinder in which an oil liquid is sealed,
The other end of the piston rod, one end of which is connected to the piston, extends through the seal block attached to the open end of the cylinder, extends outside the cylinder, and the seal block slides on the piston rod. A double seal composed of an O-ring for resiliently urging the rod seal toward the piston rod, and an oil seal held in two stages in the cylinder axial direction, and an oil reservoir between the double seal and the oil seal. The pressure in the cylinder increases in a cylinder device in which the oil in the oil sump chamber escapes to an annular chamber between the cylinder and an outer cylinder surrounding the cylinder through an oil passage provided in a seal block. In this case, a pressure holding means is provided in the oil passage so that the pressure in the oil reservoir increases when the pressure is increased.

According to the third aspect of the present invention, when oil leakage from the first-stage double seal increases by the pressure holding means between the oil reservoir and the annular chamber, the pressure in the oil reservoir is reduced. As a result, the pressure difference between the cylinder inner chamber and the oil reservoir becomes smaller, and the O-ring is not strongly compressed. Therefore, the urging force of the O-ring does not increase so much, and the rod seal is strongly pressed against the piston rod. Will not be.

[0015]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIGS. 1 to 3 show a first embodiment of the present invention. In addition, the embodiment described below,
This is a modification of the sealing means 4 of the hydraulic cylinder provided in the suspension control device, and its entire structure is the same as that shown in FIG. 10 described above. The same parts are given the same reference numerals. In the first embodiment, the rod guide 15 constituting the seal block 17 of the seal means 4 includes a guide body 30 disposed on the cylinder 1 side and a lid 31 disposed on the lock ring 16 side. I have.

The guide body 30 has a small diameter portion 3 having a small outer diameter.
0a and a large-diameter portion 30b having a large outer diameter. The small-diameter portion 30a is fitted to the cylinder 1 via a sealing member 32, and the large-diameter portion 30b is connected to the outer cylinder 5 via a sealing member 33. To close the opening ends of the cylinder inner chamber 1a and the drain chamber 6 in a liquid-tight manner. Lid 31
Is fitted to the upper surface of the guide body 30 by screwing the lock ring 16 into the outer cylinder 5, and in this state,
That is, between the lower surface of the lid 31 and the upper surface of the guide body 30, an annular groove 34 opened toward the piston rod 3 for accommodating the double seal 20 composed of the rod seal 18 and the O-ring 19. (FIG. 2) is formed. A bush 35 is provided on the inner periphery of the guide body 30.
Are fitted, and the piston 2 in the cylinder 1 (FIG. 1)
The piston rod 3 extended from 0) is in indirect sliding contact with the guide body 30 via the bush 35.

As shown in FIG. 3, an annular groove 36 is formed on the outer peripheral surface of the large-diameter portion 30b of the guide main body 30, and the annular groove 36 is formed on the outer peripheral surface of the guide main body 30. The directional groove 37 communicates with the drain chamber 6 as an annular chamber, and communicates with the upper surface of the guide main body 30 through a radial hole 38a and an axial hole 38b provided inside the guide main body 30 (FIG. 3). . On the other hand, the upper and lower surfaces and the outer peripheral surface of the lid 31 are provided with the axial holes 3 of the guide body 30.
8b and a series of grooves 39 connected to the oil reservoir 22 are formed. The annular groove 36, the axial groove 37, the radial hole 38 a and the axial hole 38 b of the guide body 30, and the groove 39 of the lid 31 constitute an oil passage 40 that communicates the oil reservoir 22 with the drain chamber 6. doing.

At the bottom of the annular groove 36 of the guide body 30, a check valve 41 as pressure holding means is provided. As shown in FIG. 3, the check valve 41 includes a valve seat 42 formed at the opening end of the radial hole 38 a, a ball 43 detachably seated on the valve seat 42, and the ball 43. An elastic band 44 made of rubber or the like urges the valve seat 42 in a seating direction. That is,
The check valve 41 always acts to close the oil passage 40, so that a predetermined oil pressure is maintained in the oil reservoir 22.

Here, as shown in FIG. 2, the rod seal 18 constituting the double seal 20 held by the rod guide 15 has a lower portion of the inner peripheral surface thereof (a portion near the cylinder inner chamber 1a). And the upper part of its outer peripheral surface (oil reservoir 2
Step portions 45 and 46 are formed on the second portion.
On the other hand, the inner peripheral portion of the guide main body 30 and the lower surface of the lid 31 (the seal receiving surface outside the cylinder in the axial direction) constituting the rod guide 15 can be fitted to the step portions 45 and 46 of the rod seal 18, respectively. Projections 47 and 48 are provided, and the projection 48 is provided so as to be located between the rod seal 18 and the O-ring 19. The inner peripheral surface of the rod seal 18 is provided with a plurality of annular grooves 49, which are intended to retain an oil film by a so-called rubbing effect, thereby reducing frictional resistance. In addition, a communication path 5 for ensuring the flow of the oil liquid between the annular groove 34 and the inner periphery of the guide main body 30 is provided at the base of the projection 47 on the guide main body 30 side.
0 is provided.

In the hydraulic cylinder configured as described above, when the oil liquid is supplied into the cylinder 1 by the oil supply / drainage means 11 (FIG. 10) and the pressure in the cylinder inner chamber 1a increases,
Oil leakage occurs from a small gap between the rod seal 18 and the piston rod 3. At this time, an oil passage 40 communicating the oil reservoir 22 and the drain chamber 6 below the oil seal 21 is provided.
Is closed by the check valve 41, the above-mentioned leaking oil is gradually stored in the oil reservoir 22, and the pressure in the oil reservoir 22 increases. As a result, the cylinder inner chamber 1a and the oil reservoir 2
2, the O-ring 19 that backs up the rod seal 18 is not compressed so strongly, so that the rod seal 18 is not strongly pressed against the piston rod 3. That is,
An increase in frictional resistance of the rod seal 18 is suppressed, and smooth expansion and contraction of the piston rod 3 is guaranteed.

Under the above-mentioned state, when the pressure in the cylinder inner chamber 1a temporarily becomes high due to the influence of the load applied to the hydraulic cylinder, the differential pressure ΔP between the cylinder inner chamber 1a and the oil reservoir 22 becomes higher.
Increases temporarily. Then, as shown in FIG. 2, the O-ring 19 in the annular groove 34 is strongly compressed between the lid 31 and the rod seal 18 and tries to press the rod seal 18 against the piston rod 3 with a strong force. At this time, the projections 48 provided on the lower surface of the lid 31 share the pressing force. As a result, the rod seal 18 is not strongly pressed against the piston rod 3 and the increase in frictional resistance is suppressed, and The smooth extension and retraction of the rod 3 is guaranteed.

On the other hand, the amount of oil leaking from between the rod seal 46 and the piston rod 3 increases and the pressure in the oil reservoir 22 increases, and the above-described differential pressure ΔP may be constantly reversed. . When the reverse rotation pressure difference (-ΔP) temporarily increases, the O-ring 19 in the annular chamber 34 is pushed down and strongly compressed between the guide body 30 and the rod seal 18 to the piston rod 3. Attempts to press with strong force. At this time, the protrusions 4 provided on the guide body 30
7 share the pressing force, and as a result, the rod seal 18
Is no longer strongly pressed against the piston rod 3, the increase in frictional resistance is suppressed, and smooth expansion and contraction of the piston rod 3 is ensured in the same manner as described above. At this time, the rod seal 18 comes into close contact with the projection 47. However, since the flow of the oil liquid inside and outside the annular groove 34 is ensured by the communication path 50, the O-ring becomes smaller as the reverse rotation differential pressure becomes smaller. 1
9 returns to the upper original position.

Thereafter, when the amount of the leaking oil further increases and the pressure in the oil reservoir 22 further increases, the check valve 41 is opened, and the oil liquid in the oil reservoir 22 flows through the oil passage 40 to the drain chamber. 6, and the above-mentioned reverse rotation differential pressure (-ΔP) does not rise more than necessary. That is, the O-ring 19
The force for pressing the rod seal 18 against the piston rod 3 is suppressed, and an increase in frictional resistance is suppressed. Therefore, by appropriately setting the valve opening pressure of the check valve 41, the differential pressure Δ
P or the reverse rotation pressure difference (−ΔP) can be kept within a predetermined range, and increase in the frictional resistance of the rod seal 18 can be suppressed. However, as shown in FIG. 4, the pressure in the oil reservoir 22 and the frictional resistance of the oil seal 21 rapidly increase when the pressure in the oil reservoir 22 exceeds about 2 kgf / cm ² (about 196 Pa). Therefore, it is desirable that the valve opening pressure of the check valve 41 be an appropriate value of ² kgf / cm ² or less.

FIG. 5 shows a second embodiment. In the second embodiment, the check valve 41 in the first embodiment is abolished, and the axial hole 38b provided in the guide main body 30 is provided with an orifice 5 as a pressure holding means.
1 in that the drain chamber 6 is opened. According to the second embodiment, the oil reservoir 22 is
The hydraulic pressure is held in the cylinder chamber 1 as described above.
The pressure difference ΔP between a and the oil reservoir 22 does not increase so much,
The O-ring 19 is no longer strongly compressed, and the rod seal 18 is no longer strongly pressed against the piston rod 3. However, according to the check valve 41,
Since the pressure in the oil reservoir 22 cannot be constantly increased, there is a limit to reducing the differential pressure ΔP. For this reason, the chance of the pressure difference increasing due to the pressure increase in the cylinder inner chamber 1a is increased. Can be suppressed from increasing.

Here, the orifice 51 is provided in the axial hole 38b (oil passage 40) as in the second embodiment, or the orifice 51 is omitted and the oil passage 4 is omitted.
When the pressure in the oil reservoir 22 is completely opened, the pressure in the oil reservoir 22 does not rise so much or almost does not rise. Therefore, only the increase in the differential pressure ΔP due to the pressure rise in the cylinder inner chamber 1a needs to be considered. In this case, 6, the projections 47 (FIG. 2) on the outer side of the guide 30 may be omitted, and the projections 48 may be provided only on the lid 31.

In this case, as shown in FIG. 7, the projection 48 is provided between the O-ring of the seal receiving surface 31a of the ring-shaped member (seal cover) 55 separate from the lid 31 and the rod seal. May be provided. The seal cover 55 is provided between the end face of the double seal 20 outside the cylinder in the axial direction and the end face of the annular groove 34 outside the cylinder in the axial direction, and has a slight clearance (0.1 to 0.2) between the piston rod 3 and the annular groove 34. mm) is formed so as to form an inner diameter, and a radial bottom surface of the annular groove 34 (the guide body 30).
Relatively large clearance between the inner peripheral surface of the
7 mm). That is, the inner peripheral surface of the seal cover 55 is substantially in sliding contact with the piston rod 3, so that even when the rod seal 18 is pressed against the piston rod 3 and deformed, the piston rod 3 and the rod guide The rod seal 18 does not bite into the gap S between the cover 31 and the cover 31. Therefore, the rod seal 18
In addition to preventing damage to itself, increase in frictional resistance to the piston rod 3 is suppressed, and smooth expansion and contraction of the piston rod 3 is more reliably ensured.
The seal cover 55 almost slidably contacts the piston rod 3 and has a relatively large clearance between the seal cover 55 and the inner peripheral surface of the guide body 30, so that when a lateral load is applied to the piston rod 3. In addition, the piston rod 3 slides radially on the seal receiving surface 31a of the lid 31 integrally with the piston rod 3, so that there is no problem such as a galling between the piston rod 3 and the seal cover 55.

When the projection 48 is formed on the seal cover 55, as shown in FIG. 8, a low friction material such as polytetrafluoroethylene is provided on the seal receiving surface 31a of the lid 31 constituting the rod guide 15. It is desirable to provide a sliding receiving plate 56 made of, so that the movement of the seal cover 55 when a lateral load is applied to the piston rod 3 becomes smooth.

[0029]

As described above in detail, according to the first aspect of the present invention, the urging force applied from the O-ring to the rod seal is suppressed by the projection provided in the annular groove of the seal block, and the rod seal is thus reduced. The piston rod is no longer strongly pressed, the frictional resistance no longer increases more than necessary, and the smooth expansion and contraction of the piston rod is guaranteed, and furthermore, the wear of the rod seal is reduced and the sealing performance is reduced. Is prevented beforehand.

According to the second aspect of the present invention, in addition to the effect of the first aspect, the seal cover provided with the protrusion prevents the rod seal from biting into the gap between the piston rod and the seal block. As a result, damage to the rod seal itself is prevented, as well as an increase in frictional resistance to the piston rod is suppressed, and smooth expansion and contraction of the piston rod is more reliably ensured.

Further, according to the third aspect of the present invention,
2. The pressure holding means prevents the pressure difference between the cylinder inner chamber and the oil reservoir between the two-stage seal from becoming unnecessarily large, so that the urging force applied to the rod seal from the O-ring is suppressed. In the same manner as in the invention, smooth expansion and contraction of the piston rod is ensured.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a main structure of a hydraulic cylinder according to a first embodiment of the present invention.

FIG. 2 is an enlarged sectional view showing a portion A in FIG. 1;

FIG. 3 is an enlarged sectional view showing a portion B in FIG. 1;

FIG. 4 is a graph showing a correlation between the pressure of the oil reservoir and the frictional resistance of the oil seal.

FIG. 5 is a cross-sectional view illustrating a main structure of a hydraulic cylinder according to a second embodiment of the present invention.

FIG. 6 is a sectional view showing another embodiment of the double seal holding unit.

FIG. 7 is a sectional view showing still another embodiment of the double seal holding section.

FIG. 8 is a sectional view showing still another embodiment of the double seal holding portion.

FIG. 9 is a sectional view showing the entire structure of a general hydraulic cylinder.

FIG. 10 is a sectional view showing a conventional seal structure.

FIG. 11 is an enlarged sectional view showing a portion C in FIG. 10;

[Explanation of symbols]

 Reference Signs List 1 cylinder 1a cylinder inner chamber 2 piston 3 piston rod 4 sealing means 5 outer cylinder 6 drain chamber (annular chamber) 15 rod guide 16 lock ring 17 seal block 18 rod seal 19 O-ring 20 double seal 21 oil seal 22 oil sump chamber Reference Signs List 30 Guide body 31 Lid 31a Seal receiving surface 40 Oil passage 41 Check valve 45, 46 Step 47, 48 Projection 51 Orifice 55 Seal cover 56 Sliding receiving plate

Continued on the front page (72) Inventor Hiroshi Murata 1116 Koizono, Ayase-shi, Kanagawa Inside Tokiko Corporation Sagami Plant

Claims (3)

[Claims] 1. A seal in which a piston is slidably fitted into a cylinder in which an oil liquid is sealed, and the other end of a piston rod having one end connected to the piston is mounted on an open end of the cylinder. The block is inserted and extended to the outside of the cylinder, and a rod seal slidably in contact with the piston rod and the rod seal are elastically urged toward the piston rod in an annular groove provided on the piston rod side of the seal block. In a cylinder device holding a double seal composed of an O-ring and an O-ring, the O-ring is connected to the rod seal between the O-ring and the rod seal on a seal receiving surface of the annular groove outside the cylinder in the axial direction. A cylinder device provided with a projection for receiving a part of an applied urging force. 2. A seal in which a piston is slidably fitted in a cylinder in which oil is sealed, and the other end of a piston rod having one end connected to the piston is mounted on an open end of the cylinder. The block is inserted and extended to the outside of the cylinder, and a rod seal slidably in contact with the piston rod and the rod seal are elastically urged toward the piston rod in an annular groove provided on the piston rod side of the seal block. The cylinder device holding a double seal composed of an O-ring and an inner surface of the piston rod between an end surface of the double seal outside the axial cylinder and an end surface of the annular groove outside the axial cylinder. A ring-shaped seal cover having a circumferential surface substantially slidably contacting the seal block is disposed so as to be movable in the radial direction of the piston rod, and the seal cover is sealed with the seal cover. A cylinder device, wherein a projection is provided between the O-ring and the rod seal on the receiving surface to receive a part of the urging force applied to the rod seal from the O-ring. 3. A seal in which a piston is slidably fitted in a cylinder in which oil is sealed, and the other end of a piston rod having one end connected to the piston is mounted on an open end of the cylinder. The block is inserted and extended to the outside of the cylinder, and the seal block is provided with a double seal including a rod seal slidably in contact with the piston rod and an O-ring for urging the rod seal toward the piston rod, and an oil seal. The two-stage holding in the cylinder axis direction, and between the double seal and the oil seal as an oil reservoir,
When the pressure in the cylinder rises in a cylinder device in which oil in the oil reservoir chamber is allowed to escape to an annular chamber between the cylinder and an outer cylinder surrounding the cylinder through an oil passage provided in a seal block. A cylinder device, wherein a pressure holding means is provided in the oil passage so as to increase the pressure in the oil reservoir.