JP4336220B2 - Oil seal structure of hydraulic shock absorber - Google Patents

Description

  The present invention relates to an oil seal structure of a hydraulic shock absorber.

  As the oil seal structure of the hydraulic shock absorber, a gas filling port is provided on the side near the tip of the damper tube, gas is sealed from the gas filling port to the inside of the damper tube, and then the oil seal and rod guide are installed in the opening of the damper tube. The gas seal is sealed by the outer peripheral lip of the oil seal, the oil seal and rod guide are held by the end crimping part of the damper tube, and the piston rod inserted through the oil seal and rod guide is Some are inserted inside the tube.

In such a conventional oil seal, in order to prevent gas leakage during gas filling, an outer peripheral lip that has a tightening margin from the beginning of the oil seal alone is sealed at a position where the opening of the damper tube does not reach the gas filling port. Although there is no allowance for tightening, the outer peripheral lip pushed out by the lip widening portion of the rod guide is sealed, and as a result, gas leakage from the opening is prevented.
JP2000-74124

  However, in the conventional oil seal, the oil seal and the rod guide are pushed into the opening of the damper tube after the gas is filled, and the oil seal and the rod guide are positioned inward of the gas fill port. When sealing, there is a risk of scratching the outer peripheral lip. That is, when the outer peripheral lip having a tightening margin or being spread passes through the gas filling port while being pressed against the damper tube, the outer lip is pressed against the edge of the gas filling port to be scratched, and the subsequent sealing performance is impaired.

  An object of the present invention is to prevent an oil seal from being damaged in an oil seal structure of a hydraulic shock absorber provided with a gas filling port on a side portion near the tip of a damper tube.

According to the first aspect of the present invention, a gas sealing port is provided in a side portion near the tip of the damper tube, and an oil seal and a rod guide are pushed into the opening of the damper tube in a laminated form, and the gas sealing port is formed by the outer peripheral lip of the oil seal. In the oil seal structure of the hydraulic shock absorber that is sealed, the oil seal and the rod guide are held by the tip crimping portion of the damper tube, and the piston rod inserted through the oil seal and the rod guide is inserted into the damper tube. on the lower surface side of the oil seal provided in contact with the elastic projections in the rod guide, resilient projections during lamination to the rod guide oil seal is to allow contact with the rod guide before the outer peripheral lip, the elastic projections of the oil seal rod When compressed by abutting against the guide, the outer peripheral lip is spread out by the lip widening part of the rod guide, causing an elastic protrusion. When a compressive elastic projections are released was separated depressing the rod guide, in which circumferential lip has to be canceled widened by lip expanding portion of the rod guide.

  According to a second aspect of the invention, in the first aspect of the invention, the oil seal is formed by connecting an elastic protrusion to an outer peripheral lip.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, the oil seal further includes elastic protrusions at a plurality of positions in the circumferential direction.

(Claim 1)
(a) In the state of a single oil seal, an oil seal having an outer peripheral lip with no allowance for the inner diameter of the damper tube can be used.

  When gas is filled, the piston rod and rod guide are pulled up to the gas filling position, the elastic protrusion of the oil seal is compressed by the rod guide, and the outer lip of the oil seal is positioned outside the gas filling port at the opening of the damper tube. In addition, by pushing the outer peripheral lip with the lip widening portion of the rod guide, the outer peripheral lip is pressed against the inner diameter of the damper tube to prevent gas leakage.

  When the lifting of the piston rod and rod guide is released after gas filling, the compression of the elastic projection on the oil seal is released, and the elastic projection restored by this pushes the rod guide down, and the outer lip of the oil seal is the lip of the rod guide. The expansion by the expanding portion is released, and the gas tube is opened slightly to prevent gas leakage by the action of the gas pressure, and comes into contact with the inner diameter of the damper tube.

  Subsequently, the oil seal and rod guide are pushed into the opening of the damper tube, and the oil seal and rod guide are positioned inward of the gas filling port. Since the protrusion pushes in the rod guide with the above-mentioned restoration, the outer peripheral lip is slightly opened as described above and passes through the gas filling port without being pressed against the inner peripheral surface of the damper tube, so that there is no scratch.

Finally, when the rod guide reaches the insertion end, the elastic protrusion of the oil seal is compressed again by the rod guide, the outer lip is pushed again by the lip expansion part of the rod guide, and the outer lip is pressed against the inner diameter of the damper tube. To prevent gas leakage. In this state, the tip of the damper tube is crimped, the oil seal and the rod guide are held by the crimped portion, and the above-described compression of the elastic projection of the oil seal and the above-described expansion of the outer peripheral lip are maintained.
In other words, after gas filling, the outer lip of the oil seal is pressed against the inner peripheral surface of the damper tube so that it can pass through the gas inlet without touching it, and the outer lip can be prevented from being damaged. The outer peripheral lip can be expanded to securely seal.

(Claim 2)
(b) Since the oil seal is formed by connecting the elastic protrusion to the outer peripheral lip, the rubber seal is good and easy to form when forming the oil seal.

(Claim 3)
(c) Since the oil seal is provided with elastic protrusions at a plurality of positions in the circumferential direction, an oil return flow path can be easily secured in the rod guide with which the elastic protrusions abut.

  1 is an overall sectional view showing a hydraulic shock absorber, FIG. 2 is a sectional view showing an oil seal structure of Example 1, FIG. 3 is a rod guide, (A) is a sectional view, (B) is a plan view, FIG. 4 shows an oil seal, (A) is a cross-sectional view, (B) is a plan view, FIG. 5 is a schematic view showing a gas sealing procedure in a damper tube, and FIG. 6 is a cross-sectional view showing an oil seal structure of Example 2. 7 shows a rod guide, (A) is a sectional view, (B) is a plan view, FIG. 8 shows an oil seal, (A) is a sectional view, (B) is a plan view, and FIG. 9 shows an embodiment. 3 is a sectional view, and (B) is a plan view.

Example 1 (FIGS. 1 to 5)
As shown in FIG. 1, the hydraulic shock absorber 10 includes a double tube in which a cylinder 12 is built in a damper tube 11, a piston rod 13 is inserted into the cylinder 12, and an axle side including an eye joint is formed below the damper tube 11. A mounting portion 14 is provided, and a vehicle body side mounting portion 15 is provided above the piston rod 13 to constitute a vehicle suspension device.

  The hydraulic shock absorber 10 has a suspension spring 17 interposed between a lower spring seat 16 on the outer periphery of the damper tube 11 and an upper spring seat (not shown) provided on a vehicle body side mounting portion 15 at an upper end portion of the piston rod 13. To do.

  The hydraulic shock absorber 10 clamps a rod guide 21, a bush 22, and an oil seal 23 for the piston rod 13 inserted into the cylinder 12 between the upper end crimping portion 24 of the damper tube 11 and the upper end portion of the cylinder 12. It is fixed.

  The hydraulic shock absorber 10 includes a piston valve device 30 and a bottom valve device 40, and controls the expansion and contraction vibration of the piston rod 13 accompanying the absorption of the impact force by the suspension spring 17 by the damping force generated by them.

(Piston valve device 30)
The piston valve device 30 is provided with a valve stopper 31, a pressure side valve device 32 including a damping valve, a piston 33, an expansion side valve device 34 including a disk valve, and a valve stopper 35 mounted on the piston rod 13. It is fixed.

  At the time of compression, the oil in the piston-side oil chamber 37A passes through the pressure-side oil passage 38A of the piston 33 to bend and deform the pressure-side valve device 32 and is led to the rod-side oil chamber 37B. Further, at the time of extension, the oil in the rod side oil chamber 37B passes through the extension side oil passage 38B (not shown) of the piston 33, bends and opens the extension side valve device 34, and is led to the piston side oil chamber 37A. Generate extension side damping force.

(Bottom valve device 40)
In the hydraulic shock absorber 10, a gap between the damper tube 11 and the cylinder 12 serves as a reservoir chamber 41, and the interior of the reservoir chamber 41 is partitioned into an oil chamber and a gas chamber. The bottom valve device 40 closes the bottom 11A of the damper tube 11 by spinning molding, and arranges a bottom piece 43 that partitions the piston-side oil chamber 37A and the reservoir chamber 41 inside the cylinder 12 at the lower end of the cylinder 12, The piston-side oil chamber 37 </ b> A and the reservoir chamber 41 can be communicated with each other through a flow path (not shown) provided in the bottom piece 43. Bolts 44 and nuts 45 are fastened to the bottom piece 43, and between the bolts 44 and nuts 45, a pressure side valve device 46 including a disc valve, a bottom piece 43, an extension side valve device 47 including a check valve, and a valve stopper 48 are provided. It is intervening.

  During compression, the oil corresponding to the volume of the piston rod 13 entering the cylinder 12 is opened by bending the pressure side valve device 46 from the piston side oil chamber 37A through the pressure side oil passage 49A of the bottom piece 43, and opening the reservoir. Extruded into the chamber 41 to obtain a compression side damping force. At the time of extension, the oil corresponding to the retraction volume of the piston rod 13 that retreats from the cylinder 12 pushes and opens the expansion side valve device 47, and the piston side oil passes from the reservoir chamber 41 via the expansion side oil passage 49 </ b> B (not shown) of the bottom piece 43. The chamber 37A is replenished.

  The hydraulic shock absorber 10 includes a first collar 51 fixed to the piston 33 side (lower side) and the rod guide 21 side (upper side) around the piston rod 13 located in the rod side oil chamber 37B of the cylinder 12. ) Is interposed between the second collar 52 loosely inserted in the rebound spring 53 that is compressed and deformed when the piston rod 13 is extended (the most extended state of the hydraulic shock absorber 10). And the rebound sheet | seat 50 is fixed to the outer periphery of the part inserted in the cylinder 12 of the piston rod 13, and the 1st color | collar 51 loaded in the lower end part of the rebound spring 53 is mounted on the rebound sheet | seat 50, and is supported.

  Further, the hydraulic shock absorber 10 has a bump stopper cap 54 attached around the upper end portion of the damper tube 11, and a bump rubber (not shown) provided on the piston rod 13 side is bump stopper when the hydraulic shock absorber 10 is compressed most. It is possible to collide with the cap 54.

  However, the hydraulic shock absorber 10 has the following oil seal structure in relation to sealing pressurized gas in the gas chamber of the reservoir chamber 41 in the gap between the damper tube 11 and the cylinder 12 (FIG. 2). FIG. 5).

  As shown in FIG. 2, the hydraulic shock absorber 10 has a gas sealing port 25 formed in a side portion near the upper end of the damper tube 11 and is covered around the upper end portion of the damper tube 11 before the bump stopper cap 54 is attached. The pressurized gas supplied by the gas sealing head to be supplied can be sealed in the reservoir chamber 41 from the gas sealing port 25.

  As shown in FIG. 3, the rod guide 21 is provided with a gas introduction path 21 </ b> A (which may be a groove or a hole) penetrating a part of the outer periphery from the upper surface to the lower surface. The rod guide 21 also has a hole-like oil return passage 21B that returns the oil scooped up by the piston rod 13 from the oil chamber 37B through the bush 22 to the reservoir chamber 41 side from the upper surface to the lower surface of the rod guide 21. Yes. The rod guide 21 is provided with a conical lip expanding portion 61 on the upper surface side, which presses against a tapered inner peripheral surface 75A of an outer peripheral lip 75 described later of the oil seal 23 and expands the outer peripheral lip 75 outward. The rod guide 21 includes an annular flat surface portion 62 (which can be a receiving portion to which the elastic protrusion 76 can contact) on the upper surface side, on which an elastic protrusion 76 described later of the oil seal 23 contacts. In the present embodiment, a flat portion 62 is provided on the upper side of the lip expanding portion 61.

  As shown in FIG. 4, the oil seal 23 includes a cored bar 71 made of a perforated disk-like flat plate that is placed on the upper end surface of the rod guide 21 and is held by the crimping portion 24 of the damper tube 11. An oil lip 72 made of rubber or the like, a check lip 73, a dust lip 74, and an outer peripheral lip 75 are provided on the metal core 71 by baking or the like. The oil lip 72 is annularly arranged below the inner periphery of the metal core 71, slidably contacts the outer peripheral surface of the piston rod 13 with its own elastic force and the tightening force of the tightening spring 72 </ b> A, and adheres to the outer periphery of the piston rod 13. Scrape off the oil. The check lip 73 is annularly arranged around the oil lip 72 on the inner peripheral side of the lower surface of the cored bar 71, comes into contact with the upper surface of the rod guide 21 by its own elasticity, and the oil scraped by the oil lip 72 is removed. The rod guide 21 is allowed to flow to the oil return flow path 21B side, and the pressurized gas in the reservoir chamber 41 has a non-return action that prevents the pressurized gas in the reservoir chamber 41 from flowing from the oil return flow path 21B side to the oil lip 72 side. The dust lip 74 is annularly arranged above the inner periphery of the metal core 71 and faces the outside. The dust strip 74 is in sliding contact with the outer peripheral surface of the piston rod 13 by its own elastic force, and external foreign matter attached to the outer periphery of the piston rod 13 is damped. Intrusion into the tube 11 is prevented. The outer peripheral lip 75 is annularly arranged on the outer periphery of the core bar 71 and below the outer periphery of the core bar 71. Although the oil seal 23 is a single product, there is no allowance for the inner diameter of the damper tube 11, but the core bar 71 is on the upper end surface of the rod guide 21. A taper-shaped inner peripheral surface 75A that is in pressure contact with the lip widening portion 61 of the rod guide 21 while being in close contact with the inner surface of the damper tube 11 is expanded by being pressed against the lip widening portion 61. Pressed.

  Then, after the gas is sealed from the gas filling port 25, the hydraulic shock absorber 10 pushes the oil seal 23 and the rod guide 21 into the opening of the damper tube 11 in a stacked manner, and the gas sealing port 25 is opened by the outer peripheral lip 75 of the oil seal 23. The oil seal 23 and the rod guide 21 are held by the crimping portion 24 of the damper tube 11 and the piston rod 13 inserted through the oil seal 23 and the rod guide 21 is inserted into the damper tube 11. To do.

  At this time, the hydraulic shock absorber 10 has an elastic protrusion 76 that contacts the flat surface portion 62 of the rod guide 21 on the lower surface side of the oil seal 23 and on the upper side of the tapered inner peripheral surface 75A of the outer peripheral lip 75 in this embodiment. It is provided. The elastic protrusion 76 is made of the same rubber as the outer peripheral lip 75, and the rod is formed before the outer peripheral lip 75 comes into contact with the rod guide 21 (tapered expanding portion 61) when the oil seal 23 is stacked on the rod guide 21. It abuts on the guide 21 (plane portion 62).

  The elastic protrusion 76 of the oil seal 23 has an annular shape that is continuous over the entire circumference in the circumferential direction, and is formed so as to be connected to the outer peripheral lip 75 so as to form one lump.

Therefore, the gas filling procedure in the hydraulic shock absorber 10 is performed as follows (FIG. 5).
(1) An oil seal 23 having an outer peripheral lip 75 with no allowance for the inner diameter of the damper tube 11 is prepared (FIG. 5A).

  (2) At the time of gas filling, as shown in FIG. 5B, the cylinder assembly (the lower end small diameter portion of the rod guide 21 is inserted into the upper end inner diameter portion of the cylinder 12 in the damper tube 11, and the bush 22 is attached to the rod guide 21. The oil seal 23 is incorporated, the piston rod 13 with the piston valve device 30 is inserted into the bush 22 and the oil seal 23), and the gas filled head is covered over the opening of the damper tube 11. With the core 71 of the oil seal 23 pressed from above by the oil seal stopper of the gas filled head, the piston rod 13 and the rod guide 21 are pulled up to the gas filled position by the lifting tool, and the elastic protrusion 76 of the oil seal 23 is moved to the rod guide. The outer peripheral lip 75 of the oil seal is positioned outward of the gas filling port 25 at the opening of the damper tube 11, and the outer peripheral lip 75 is positioned at the lip widening portion 61 of the rod guide 21. The gas is sealed into the damper tube 11 from the gas filling port 25 in a state where the outer peripheral lip 75 is pressed against the inner diameter of the damper tube 11 to prevent gas leakage.

  (3) When the lifting of the piston rod 13 and the rod guide 21 by the lifting tool is released after gas filling, the compression of the elastic protrusion 76 of the oil seal 23 is released as shown in FIG. The protrusion 76 pushes down and separates the rod guide 21 (h in FIG. 5C), and the outer peripheral lip 75 of the oil seal 23 is released from being expanded by the lip expanding portion 61 of the rod guide 21, and gas pressure is applied by the action of gas pressure. It opens slightly to prevent leakage and contacts the inner diameter of the damper tube 11.

  (4) Subsequently, the oil seal 23 and the rod guide 21 are pushed into the opening of the damper tube 11, and the oil seal 23 and the rod guide 21 are positioned inward of the gas filling port 25, so that the gas filling port 25 is formed. When sealing, the elastic protrusion 76 of the oil seal pushes the rod guide 21 with the above-mentioned restoration, so that the outer peripheral lip 75 remains slightly open as described above and is not pressed against the inner peripheral surface of the damper tube 11. It passes through the gas filling port 25 and is not scratched.

  (5) Finally, when the cylinder 12 integrated with the rod guide 21 abuts against the bottom 11A of the damper tube 11 and the rod guide 21 reaches the pushing-in end, the elasticity of the oil seal 23 is obtained as shown in FIG. The protrusion 76 is compressed again by the flat portion 62 of the rod guide 21, the cored bar 71 comes into close contact with the upper end surface of the rod guide 21, and the outer peripheral lip 75 is expanded again by the lip expanding portion 61 of the rod guide 21. The outer peripheral lip 75 is pressed against the inner diameter of the damper tube 11 to prevent gas leakage. In this state, the tip of the damper tube 11 is crimped, and the crimping portion 24 holds the oil seal 23 and the rod guide 21 between the bottom portion 11A of the damper tube 11 via the cylinder 12, and the oil seal The above-described compression of the 23 elastic protrusions 76 and the above-described expansion of the outer peripheral lip 75 are maintained.

According to the present embodiment, the following operational effects can be obtained.
(a) After gas filling, the outer peripheral lip 75 of the oil seal 23 is pressed against the inner peripheral surface of the damper tube 11 and can pass through the gas inlet 25 without contacting, and the outer peripheral lip 75 can be prevented from being damaged. When the tip is caulked, the outer peripheral lip 75 of the oil seal 23 can be expanded to securely seal.

  (b) Since the oil seal 23 is formed by connecting the elastic protrusion 76 to the outer peripheral lip 75, when the oil seal 23 is formed, the surroundings of the rubber are good and easy to form.

Example 2 (FIGS. 6 to 8)
The hydraulic shock absorber 10 of the second embodiment is different from the hydraulic shock absorber 10 of the first embodiment in that the flat portion 62 of the rod guide 21 is connected to the upper end surface (the oil seal 23 of the oil seal 23) as shown in FIGS. The elastic protrusion 76 of the oil seal 23 is provided on the inner peripheral side of the outer peripheral lip 75 on the lower surface of the core metal 71 and between the outer peripheral lip 75 as shown in FIG. It exists in the state through the valley.

  Also in the second embodiment, the elastic protrusion 76 is formed so that the rod guide 21 (planar portion 62) comes before the outer peripheral lip 75 contacts the rod guide 21 (lip expanding portion 61) when the oil seal 23 is laminated on the rod guide 21. Abut. The elastic protrusion 76 has an annular shape that is continuous over the entire circumference in the circumferential direction, and is formed by being connected to the outer peripheral lip 75 via a thin rubber portion on the cored bar 71.

Example 3 (FIG. 9)
The hydraulic shock absorber 10 of the third embodiment is different from the hydraulic shock absorber 10 of the second embodiment in that the elastic protrusion 76 of the oil seal 23 is connected to the inner periphery of the outer peripheral lip 75 on the lower surface of the metal core 71 as shown in FIG. (It forms one lump with the outer peripheral lip 75) and is distributed at a plurality of positions in the circumferential direction. The rod guide 21 is the same as the rod guide 21 of the third embodiment.

  Also in the third embodiment, the elastic protrusion 76 is formed so that the rod guide 21 (planar portion 62) comes before the outer peripheral lip 75 contacts the rod guide 21 (lip expanding portion 61) when the oil seal 23 is stacked on the rod guide 21. Abut.

  According to the third embodiment, since the oil seal 23 is provided with the elastic protrusions 76 at a plurality of positions in the circumferential direction, the oil return channel 21B can be easily secured in the rod guide 21 with which the elastic protrusions 76 abut.

  Although the embodiments of the present invention have been described in detail with reference to the drawings, the specific configuration of the present invention is not limited to these embodiments, and even if there is a design change or the like without departing from the gist of the present invention. It is included in the present invention. For example, the elastic protrusion provided on the oil seal of the present invention corresponds to the receiving portion such as the flat portion of the rod guide, and is formed in any number and at any position as long as the oil return flow path of the rod guide is not blocked. May be.

FIG. 1 is an overall cross-sectional view showing a hydraulic shock absorber. FIG. 2 is a cross-sectional view showing the oil seal structure of the first embodiment. 3A and 3B show a rod guide, where FIG. 3A is a cross-sectional view and FIG. 3B is a plan view. 4A and 4B show an oil seal, where FIG. 4A is a sectional view and FIG. 4B is a plan view. FIG. 5 is a schematic diagram showing a procedure for gas filling into the damper tube. FIG. 6 is a cross-sectional view showing an oil seal structure according to the second embodiment. FIG. 7 shows a rod guide, where (A) is a cross-sectional view and (B) is a plan view. FIG. 8 shows an oil seal, (A) is a sectional view, and (B) is a plan view. FIG. 9 shows an oil seal of Example 3, (A) is a sectional view, and (B) is a plan view.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Hydraulic buffer 11 Damper tube 13 Piston rod 21 Rod guide 23 Oil seal 24 Clamping part 25 Gas filling port
61 Lip expansion part 75 Outer peripheral lip 76 Elastic protrusion

Claims (3)

A gas inlet is provided on the side near the tip of the damper tube, and an oil seal and a rod guide are pushed into the opening of the damper tube in a stacked manner, and the gas inlet is sealed by the outer peripheral lip of the oil seal. In the oil seal structure of the hydraulic shock absorber, in which the oil seal and the rod guide are held by the tip caulking portion, and the piston rod inserted through the oil seal and the rod guide is inserted into the damper tube.
An elastic protrusion that contacts the rod guide is provided on the lower surface side of the oil seal, and when the oil seal is stacked on the rod guide, the elastic protrusion can contact the rod guide before the outer lip ,
When the elastic protrusion of the oil seal contacts the rod guide and is compressed, the outer peripheral lip is pushed out by the lip widening part of the rod guide, the compression of the elastic protrusion is released, and the elastic protrusion pushes down the rod guide. An oil seal structure for a hydraulic shock absorber , wherein the outer lip is released from being pushed by the lip expanding portion of the rod guide when the lip is expanded .   The oil seal structure for a hydraulic shock absorber according to claim 1, wherein the oil seal is formed by connecting an elastic protrusion to an outer peripheral lip.   The oil seal structure for a hydraulic shock absorber according to claim 1 or 2, wherein the oil seal is provided with elastic protrusions at a plurality of positions in a circumferential direction.

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