JP2013204669A - Suspension device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress a lubrication shortage at a part with a foreign matter or a defect with respect to improvement of a suspension device.SOLUTION: A suspension device includes an air chamber A formed inside of an outer tube 1 and an inner tube 2, a cylindrical clearance 3 formed between overlapping parts of the outer tube 1 and the inner tube 2, an outer bearing 4 held on an inner periphery of the outer tube 1 to come into sliding contact with an outer peripheral surface of the inner tube 2, and an oil seal 50 that is serially held on an inner periphery closer to an outside air side than the outer bearing 4 of the outer tube 1 and closes an outside air side opening of the cylindrical clearance 3. The cylindrical clearance 3 stores a lubricant, and communicates with the air chamber A via a hole 20 formed in the inner tube 2. The cylindrical clearance 3 includes a free piston 6 whose specific gravity is lighter than that of the lubricant and which is axially movable in a fixed range of the cylindrical clearance 3.

Description

  The present invention relates to an improvement of a suspension device.

  In general, in transportation equipment such as automobiles and motorcycles, a suspension device is interposed between a vehicle body and a wheel, and the suspension device suppresses an impact caused by road surface unevenness from being transmitted to the vehicle body.

  The suspension device includes a suspension spring that elastically supports the vehicle body and a shock absorber that generates a damping force. The suspension spring absorbs an impact caused by road surface unevenness, and a telescopic motion associated with the impact absorption. Is suppressed by the shock absorber.

  For example, a suspension device for suspending a front wheel in a straddle-type vehicle such as a motorcycle is called a front fork, and the suspension device main body includes an outer tube and an inner tube that is inserted into and retracted from the outer tube. The suspension spring and the shock absorber are accommodated in the suspension device main body.

  Moreover, in the said front fork, what is sealing and enclosing gas in a suspension apparatus main body, producing the reaction force according to the compression amount of the suspension apparatus main body, and making it function as an air spring is known ( Patent Document 1).

  The front fork stores the lubricating liquid in a cylindrical gap formed between the overlapping portions of the outer tube and the inner tube, and holds an annular oil seal on the inner periphery of the opening end of the outer tube. The gas is sealed in the main body of the suspension device by bringing the oil seal into sliding contact with the inner tube through the liquid film of the lubricating liquid.

JP 2010-164167 A

  However, when the gas is compressed and sealed in the suspension device main body and functions as a suspension spring like the above-described conventional front fork, the following problems may be pointed out.

  That is, the front fork is used in a harsh environment, foreign matter is caught in the inner peripheral surface of the oil seal that is covered with muddy water and slidably contacts the inner tube, or the outer peripheral surface of the inner tube that is slidably contacted by the oil seal is In the case of wrinkling, there is a possibility that the liquid film of the lubricating liquid is cut off at the foreign matter or the wrinkle portion and the lubrication is partially insufficient.

  And if the gas tightness is lowered at the part where the lubrication is insufficient and the gas in the suspension device main body leaks to the outside of the suspension device main body (outside air side), the internal pressure of the air chamber is lowered and the predetermined reaction force cannot be obtained. The ride comfort of the vehicle may be deteriorated.

  Accordingly, an object of the present invention is to use a front fork (suspension device) in a harsh environment, where foreign matter is caught between the inner peripheral surfaces of the oil seal that is in sliding contact with the inner tube, or the outer periphery of the inner tube that is in sliding contact with the oil seal. It is to provide a suspension device that can positively supply a lubricating liquid to the foreign matter or the portion of the heel even when the surface is crushed by a stepping stone or the like, thereby suppressing the lack of lubrication. .

  Means for solving the above problems include an outer tube, an inner tube inserted into the outer tube so as to be able to appear and retract, and formed inside the outer tube and the inner tube so as to be sealed while gas is compressed. An air chamber, a cylindrical gap formed between overlapping portions of the outer tube and the inner tube, an outer bearing held on the inner periphery of the outer tube and in sliding contact with the outer peripheral surface of the inner tube, and the outer A suspension device comprising an oil seal that is held in series with the outer bearing on the inner circumference of the tube outside the outer bearing and is in sliding contact with the outer circumferential surface of the inner tube and closes the outside air opening of the cylindrical gap. In addition, the cylindrical gap contains the lubricating liquid and has the air through the hole formed in the inner tube. It communicates with, the aforementioned cylindrical gap, lighter specific gravity than the lubricating fluid, is that the free piston which can move a certain range in the axial direction of the tubular gap is provided.

  According to the present invention, since the free piston is provided in the cylindrical gap, foreign matter is sandwiched between the inner peripheral surfaces of the oil seal that is in sliding contact with the inner tube, or the outer peripheral surface of the inner tube that is in sliding contact with the oil seal is a stepping stone. Even when it gets stuck due to, for example, it becomes possible to positively supply the lubricating liquid to the foreign matter or the wrinkle portion to suppress the lack of lubrication.

It is a front view which partially cuts and shows the principal part of the front fork which is a suspension apparatus concerning one embodiment of this invention. It is a top view which expands and shows the outer side bearing of the front fork which is a suspension apparatus concerning one embodiment of this invention. It is a front view which expands the principal part of the front fork which is a suspension apparatus concerning other embodiment of this invention, and shows it partially notching. It is the front view which shows the modification of the front fork which is a suspension apparatus concerning one embodiment of this invention, expands the deformed part, and is partially cut away. It is XX sectional drawing of FIG.

  A suspension device according to an embodiment of the present invention will be described below with reference to the drawings. The same reference numerals given throughout the several drawings indicate the same or corresponding parts.

  As shown in FIG. 1, the suspension device according to the present embodiment includes an outer tube 1, an inner tube 2 that can be inserted into and retracted into the outer tube 1, and an inner side of the outer tube 1 and the inner tube 2. Is held in the inner periphery of the outer tube 1, the air gap A that is formed while the gas is compressed and sealed, the cylindrical gap 3 formed between the overlapping portions of the outer tube 1 and the inner tube 2, and The outer bearing 4 that is in sliding contact with the outer peripheral surface of the inner tube 2 and the outer periphery of the inner tube 2 that is held in series with the outer bearing 4 on the inner periphery of the outer tube 1 on the outside air side of the outer bearing 4. And an oil seal 50 that slides on the surface and closes the opening on the outside of the cylindrical gap 3.

  The cylindrical gap 3 contains the lubricating liquid and communicates with the air chamber A through a hole 20 formed in the inner tube 2. The cylindrical gap 3 includes the lubricating liquid. A free piston 6 having a lighter specific gravity and capable of moving in the axial direction within a certain range of the cylindrical gap 3 is provided.

  Hereinafter, in detail, the suspension device according to the present embodiment is a front fork that suspends the front wheel of a straddle-type vehicle such as a motorcycle. Although not shown, the outer tube 1 is interposed via a vehicle body side bracket. The inverted front fork is connected to the steering shaft on the vehicle body side and the inner tube 2 is connected to the axle of the front wheel via the wheel side bracket.

  Furthermore, the outer tube 1 and the inner tube 2 constitute a suspension device main body F, and the upper and lower openings in FIG. 1 of the suspension device main body F are closed by a cap member and the wheel-side bracket (not shown). . In addition, in the suspension apparatus main body F, the outside air side opening of the cylindrical gap 3 formed between the overlapping portions of the outer tube 1 and the inner tube 2 is closed by the seal member 5. For this reason, the inside of the suspension device main body F is partitioned from the outside air side, and the working fluid or gas can be sealed in the suspension device main body F.

  In the suspension device main body F, a shock absorber D is accommodated inside the outer tube 1 and the inner tube 2, and a reservoir R is formed outside the shock absorber D. The reservoir R stores a working fluid for temperature compensation and volume compensation of the shock absorber D, and an air chamber A is formed on the upper side through the liquid surface. Gas is sealed while being compressed.

  Further, since the air chamber A expands and contracts according to the expansion and contraction of the suspension device main body F, the gas enclosed in the air chamber A generates a reaction force corresponding to the compression amount of the suspension device main body F, It functions as a suspension spring (air spring) that elastically supports the vehicle body by always urging the suspension device main body F in the extending direction. For this reason, the front fork according to the present embodiment is reduced in weight by eliminating a suspension spring made of a metal coil spring. In the present embodiment, the hydraulic fluid is a liquid such as water, an aqueous solution, or oil, and the gas is an inert gas such as nitrogen.

  Subsequently, the configuration of the shock absorber D accommodated in the suspension device main body F may adopt any known configuration, and although not shown in detail, the shock absorber D is the axis of the suspension device main body F. A cylinder 9 that stands up in the section, a rod (not shown) that can be moved into and out of the cylinder 9 as the suspension device main body F expands and contracts, and is held at the tip of the rod and is in sliding contact with the inner peripheral surface of the cylinder 9. A piston (not shown). In the cylinder 9, two chambers (not shown) that are partitioned by the piston and filled with the working fluid are formed.

  Further, although not shown, the shock absorber D includes a flow path that communicates the two chambers, and a damping force generating means such as a leaf valve or an orifice that provides resistance to the working fluid that passes through the flow path. .

  By providing the above configuration, the hydraulic fluid in one chamber that is pressurized when the front fork is expanded and contracted moves through the flow path to the other chamber. A damping force due to the resistance is generated, and the expansion and contraction motion of the front fork can be suppressed.

  Subsequently, a lubricating liquid is accommodated in the cylindrical gap 3 formed between the overlapping portion of the outer tube 1 and the inner tube 2 of the suspension device main body F. In this embodiment, the lubricating liquid is composed of oil having a higher viscosity than the hydraulic fluid used in the shock absorber D or grease having a low consistency, but the same fluid as the hydraulic fluid used in the shock absorber D is used. You may do that.

  Further, the cylindrical gap 3 includes an outer bearing 4 which is held on the inner periphery at the lower end side in FIG. 1 of the outer tube 1 and is in sliding contact with the outer peripheral surface of the inner tube 2, and an outer periphery on the upper end side in FIG. An inner bearing 8 is provided which is held and slidably contacts the inner peripheral surface of the outer tube 1 and is disposed on the anti-oil seal side (anti-outside air side) of the outer bearing 4. The outer bearing 4 and the inner bearing 8 support the inner tube 2 so that the outer tube 1 can protrude into and out of the outer tube 1.

  Further, the cylindrical gap 3 is disposed between the sliding gap 30 disposed on the anti-oil seal side (anti-outside air side) of the outer bearing 4 and the communication path disposed between the outer bearing 4 and the oil seal 50. A liquid reservoir chamber 31 communicating with the sliding gap 30 via L is formed. When the front fork is initially set (when assembly is completed, maintenance is completed, etc.), the sliding gap from the liquid reservoir chamber 31 is formed. The lubricating liquid is stored over 30.

  Subsequently, a free piston 6 that is formed in an annular shape and is disposed on the outer periphery of the inner tube 2 is provided in the sliding gap 30. The free piston 6 is lighter in specific gravity than the lubricating liquid, has an inner diameter slightly larger than the outer diameter of the inner tube 2, and does not have a tightening allowance for the inner tube 2.

  Further, since the sliding gap 30 communicates with the air chamber A through the hole 20 formed in the inner tube 2, the internal pressure of the air chamber A acts on the lubricating liquid via the free piston 6. . The hole 20 formed in the inner tube 2 is provided on the inner bearing side of the non-sliding contact portion 2a where the outer bearing 4 does not slide in the inner tube 2, and always faces the sliding gap 30. Yes.

  On the other hand, in the outer tube 1, an enlarged diameter portion 10 is formed on the outer bearing side of the non-sliding contact portion 1 a where the inner bearing 8 is not slidably contacted. It always faces the sliding gap 30. Further, an annular step surface 11 is formed at the boundary of the enlarged diameter portion 10 where the inner diameter changes in the non-slidable contact portion 1 a, and this step surface 11 is outside air than the hole 20 formed in the inner tube 2. Placed on the side.

  And the said free piston 6 is arrange | positioned at the inner peripheral side of the said enlarged diameter part 10, The outer diameter is formed a little smaller than the internal diameter of the said enlarged diameter part 10, and it is not compressed by the outer tube 1. ing. For this reason, in this embodiment, the free piston 6 moves in the axial direction (vertical direction in FIG. 1) from the position contacting the outer bearing 4 to the position contacting the stepped surface 11 in the sliding gap 30. be able to.

  Further, at the time of initial setting of the front fork, the level of the lubricating liquid contained in the sliding gap 30 is set so that the free piston 6 floats on the level of the lubricating liquid. For this reason, at the initial setting of the front fork, the internal pressure of the air chamber A acts on the lubricating liquid via the free piston 6, and the weight of the free piston 6 itself also acts on the lubricating liquid, so that the lubricating liquid is pressurized. ing.

  Subsequently, in the liquid reservoir chamber 31 formed between the outer bearing 4 and the oil seal 50 in the cylindrical gap 3, a washer 7 that contains lubricating liquid and is held on the inner periphery of the outer tube 1 is provided. Is arranged.

  As shown in FIG. 1, the washer 7 is formed in an inverted L-shaped cross section, as shown in FIG. 1, and has a stopper portion 70 protruding to the inner peripheral side, and an outside air side (see FIG. 1) and a cylindrical portion 71 provided continuously to the outer peripheral portion. The outer bearing 4 is supported by the stopper portion 70. Further, since the inner circumference of the cylindrical portion 71 is formed to have a larger diameter than the inner circumference of the stopper portion 70, the volume of the liquid reservoir chamber 31 can be increased.

  Further, the inner periphery of the stopper portion 70 is formed to have a larger diameter than the inner tube 2, and an annular gap 7 a is formed between the inner periphery of the stopper portion 70. For this reason, the lubricating liquid can easily move on the inner peripheral side of the washer 7 without partitioning the cylindrical gap 3 with the washer 7.

  Subsequently, the communication path L communicating the sliding gap 30 and the liquid reservoir 31 is embodied in the outer bearing 4 in the present embodiment. As shown in FIG. 2, the outer bearing 4 includes joint portions 40 and 41 that are formed in a C-shape and face each other. Then, the gap between the joint portions 40 and 41 is caused to function as the communication path L, and the lubricating liquid contained in the sliding gap 30 is quickly moved to the liquid reservoir chamber 31 side.

  Returning, the sealing member 5 for closing the opening on the outside side of the cylindrical gap 3 is formed in an annular shape as shown in FIG. 1, and is an oil seal disposed on the liquid reservoir side (upper side in FIG. 1). 50 and a dust seal 51 arranged in series on the outside air side of the oil seal 50. The oil seal 50 includes an oil seal lip 50a that extends toward the inner peripheral liquid reservoir and whose tip is pressed against the outer peripheral surface of the inner tube 2 by a garter spring (not shown) attached to the outer periphery. Yes. The dust seal 51 includes a dust seal lip 51a that extends toward the inner and outer air sides and that has a tip portion pressed against the outer peripheral surface of the inner tube 2 by a garter spring (not shown) attached to the outer periphery.

  By providing the above configuration, the seal member 5 scrapes off the foreign matter adhering to the outer peripheral surface of the inner tube 2 with the dust seal lip 51a, so that the foreign matter is sandwiched between the inner peripheral surface of the oil seal lip 50a and the inner portion of the oil seal lip 50a. Suppresses the peripheral surface from getting stuck with foreign matter. Further, the seal member 5 scrapes off the lubricating liquid adhering to the outer peripheral surface of the inner tube 2 by the oil seal lip 50a, prevents the lubricating liquid from flowing out to the outside air side, and removes the oil seal lip 50a from the lubricating liquid. The hydraulic fluid and gas can be sealed inside the suspension device main body F and kept airtight by being brought into sliding contact with the outer peripheral surface of the inner tube 2 through the liquid film.

  Next, the effect of the front fork as a suspension device according to the present embodiment will be described. At the initial setting of the front fork according to the present embodiment, the liquid level of the lubricating liquid is located on the side opposite to the outside air (upper side in FIG. 1) within the movable range of the free piston 6, and the free piston is positioned on the liquid level of the lubricating liquid. 6 is set to float.

  For this reason, the lubricating liquid in the cylindrical gap 3 receives the internal pressure of the air chamber A through the free piston 6 and is pressurized by the weight of the free piston 6 itself. The space is filled with the lubricant.

  Accordingly, the front fork is used in a harsh environment, foreign matter is caught between the inner peripheral surfaces of the oil seal 50 that is in sliding contact with the inner tube 2, or the outer peripheral surface of the inner tube 2 that is in sliding contact with the oil seal 50 is Even when it is attached, it is possible to positively supply the lubricating liquid to the foreign matter or the wrinkle portion, and to suppress the lack of lubrication in the foreign matter or the wrinkle portion.

  Further, since insufficient lubrication is suppressed, airtightness can be maintained, and the gas in the air chamber A is prevented from leaking out of the suspension device main body F (outside air side), and the ride comfort of the vehicle is deteriorated. It is possible to suppress this.

  Further, in this situation, since the lubricating liquid gradually travels down the outer peripheral surface of the inner tube 2 exposed from the outer tube 1, the user is informed that the lubricating liquid is leaking, It becomes possible to make it easy to take measures such as replacing the oil seal 50 and repairing the wrinkles.

  Subsequently, when the liquid level of the lubricating liquid falls to the outside air side, for example, when the free piston 6 is not floated on the liquid level of the lubricating liquid located in the communication path L or the liquid reservoir chamber 31, the suspension device main body is moved from the air chamber A. Since the gas that is about to flow out of F passes through the gap between the free piston 6 and the inner tube 2, the free piston 6 hinders the movement of the gas and delays the decrease in the internal pressure of the air chamber A due to the outflow of gas. Is possible.

  Further, as in the present embodiment, when the front fork eliminates the suspension spring made of the coil spring and causes the gas accommodated in the air chamber A to function as the suspension spring, the front fork provided with the suspension spring made of the coil spring; In comparison, since the ride comfort of the vehicle greatly changes due to a decrease in the internal pressure of the air chamber A, it is particularly effective to suppress insufficient lubrication as in the present invention.

  In the present embodiment, since the viscosity of the lubricating liquid is higher than that of the hydraulic fluid for generating damping force used in the shock absorber D, the lubricating liquid is sandwiched between the inner peripheral surfaces of the oil seal 50 that is in sliding contact with the inner tube 2. It is easy to fill the foreign matter and the wrinkle portion formed on the outer peripheral surface of the inner tube 2 with which the oil seal 50 is in sliding contact. For this reason, the effect which suppresses that lubrication becomes insufficient in the said foreign material and the said wrinkle part is high, and it is easy to suppress that a partial airtight fall occurs.

  Further, in this embodiment, even if a liquid different from the working liquid is used as the lubricating liquid, the free piston 6 floats on the liquid surface of the lubricating liquid when the front fork is initially set. It is difficult for the liquid to mix, and the viscosity of the lubricating liquid can be maintained high.

  Further, in the present embodiment, the step surface 11 that restricts the movement of the free piston 6 toward the non-outside air side (upper side in FIG. 1) is located on the outside air side with respect to the hole 20 formed in the inner tube 2. For this reason, even if the free piston 6 moves in the sliding gap 30 due to vibrations or impacts input from the road surface, the free piston 6 stops at the stepped surface 11 and the lubricating liquid passes through the hole 20 on the reservoir side (inside the inner tube 2). It is possible to suppress the movement.

  Further, in the present embodiment, the free piston 6 is formed in an annular shape, does not have a tightening allowance with respect to the inner tube 2, and is set so as not to be compressed by the outer tube 1. For this reason, it becomes possible to move the free piston 6 according to the position of the liquid surface of the lubricating liquid while suppressing the free piston 6 from mixing the lubricating liquid and the working liquid. Further, the free piston 6 does not hinder the reciprocating motion of the inner tube 2.

  Next, a front fork as a suspension device according to another embodiment of the present invention will be described with reference to FIG. In the present embodiment, the shape of the free piston and the outer bearing side of the sliding gap is different from that of the embodiment, and the other configurations and the effects thereof are the same as those of the embodiment. Therefore, here, a configuration different from that of the embodiment will be mainly described. The same reference numerals are given to the same configurations as those in the embodiment, and the description of the embodiment is referred to, and the detailed description thereof is omitted here.

  In the present embodiment, the free piston 6A is formed in an annular shape as in the embodiment, and has a specific gravity lighter than that of the lubricating liquid. And in this Embodiment, free piston 6A consists of the column-shaped main-body part 60, and the conical part 61 connected to the external air side of this main-body part 60, and an outer periphery is gradually diameter-reduced toward the external air side. .

  In the state where the free piston 6 </ b> A floats on the liquid surface of the lubricating liquid, the main body portion 60 is formed with an inner diameter slightly larger than the outer diameter of the inner tube 2, and the outer diameter is an enlarged diameter of the outer tube 1. It is formed slightly smaller than the inner diameter of the portion 10, does not have a tightening allowance for the inner tube 2, and is not compressed by the outer tube 1. Furthermore, the free piston 6A in the present embodiment is made of an elastic body such as rubber and can be elastically deformed.

  Subsequently, in the present embodiment, a slope portion 12 whose inner diameter gradually decreases toward the outside air side is continuously provided on the outside air side of the enlarged diameter portion 10 of the outer tube 1, and the slope portion 12 and the inner tube 2 are connected. That is, an annular pocket 32 is formed on the outer bearing side in the sliding gap 30A.

  And, in the middle of the pocket 32, the cross-sectional area when the pocket 32 is cut in the radial direction (left and right direction in FIG. 3) is the cross section when the free piston 6A is cut in the radial direction (left and right direction in FIG. 3). It becomes smaller than the area. For this reason, when the free piston 6A receives the internal pressure of the air chamber A and moves to the outside air side, the movement to the outside air side is regulated in the middle of the pocket 32.

  That is, the free piston 6A of the present embodiment can move in the axial direction from the position where movement is restricted by the pocket 32 to the position where it abuts on the step surface 11 (see FIG. 1) in the cylindrical gap 30A. .

  Next, the effect of the front fork as a suspension device according to the present embodiment will be described. Also in the present embodiment, as in the first embodiment, at the time of initial setting of the front fork, the liquid level of the lubricating liquid is located on the side opposite to the outside air (upper side in FIG. 3) within the movable range of the free piston 6A. The free piston 6A is set to float on the surface of the lubricating liquid.

  For this reason, the lubricating liquid in the cylindrical gap 3 receives the internal pressure of the air chamber A through the free piston 6A and is pressurized by the weight of the free piston 6A itself, and the free piston 6A and the oil seal 50 The space is filled with the lubricant.

  Therefore, as in the embodiment, the front fork is used in a harsh environment, foreign matter is sandwiched between the inner peripheral surfaces of the oil seal 50 that is in sliding contact with the inner tube 2, or the inner tube 2 in which the oil seal 50 is in sliding contact. Even when the outer peripheral surface of the slag is clogged with a stepping stone or the like, it is possible to positively supply a lubricating liquid to the foreign matter or the part of the heel so as to suppress the lack of lubrication at the foreign matter or the heel part. It becomes possible.

  Further, since insufficient lubrication is suppressed, airtightness can be maintained, and the gas in the air chamber A is prevented from leaking out of the suspension device main body F (outside air side), and the ride comfort of the vehicle is deteriorated. It is possible to suppress this.

  Further, in this situation, since the lubricating liquid gradually travels down the outer peripheral surface of the inner tube 2 exposed from the outer tube 1, the user is informed that the lubricating liquid is leaking, It becomes possible to make it easy to take measures such as replacing the oil seal 50 and repairing the wrinkles.

  Subsequently, when the level of the lubricating liquid decreases and the free piston 6A moves along the pocket 32 to the outside air side, the movement of the free piston 6A is regulated in the middle of the pocket 32. When the internal pressure of the air chamber A acts on the free piston 6A with the liquid level of the lubricating liquid further lowered, the free piston 6A is pressed into the pocket 32 (two-dot chain line in FIG. 3).

  For this reason, the outer bearing side of the cylindrical gap 30 is plugged with the free piston 6A, and the free piston 6A hinders the movement of the gas that is about to flow out of the suspension device main body F. It is possible to delay the decrease in the internal pressure of the chamber A.

  In the present embodiment, since the free piston 6A includes the conical portion 61, the free piston 6A is easily inserted into the pocket 32.

  Although preferred embodiments of the present invention have been described in detail above, it should be understood that modifications, variations and changes may be made without departing from the scope of the claims.

  For example, the suspension device according to the above embodiment is a front fork that suspends a front wheel in a straddle-type vehicle such as a motorcycle, but a rear cushion unit for a rear wheel in a straddle-type vehicle, an automobile, etc. It may be a suspension device for other transportation equipment.

  Moreover, in the said embodiment, although between the joint parts 40 and 41 of the outer side bearing 4 formed in C ring shape functions as the communicating path L which connects the sliding gaps 30 and 30A and the liquid reservoir chamber 31, For example, as shown in FIGS. 4 and 5, a plurality of grooves 13 that are formed along the axial direction on the inner peripheral surface of the outer tube 1 that holds the outer bearing 4 and are arranged side by side in the circumferential direction. And the space between the groove 13 and the outer bearing 4 may function as the communication path L. In this case, it is preferable to provide a notch along the radial direction in the stopper portion 70 of the washer 7 in order to move the lubricating liquid passing through the groove 13 toward the liquid reservoir. FIG. 4 shows a modification of one embodiment, but other embodiments can be similarly modified.

  Further, in each of the above embodiments, the liquid level of the lubricating liquid at the time of initial setting of the front fork is set on the outside air side with respect to the step surface 11 of the outer tube 1. However, when the lubricating liquid and the working liquid may be mixed, such as when the working liquid used in the shock absorber D is used as the lubricating liquid, the level of the lubricating liquid at the initial setting is the stepped surface 11 of the outer tube 1. It may be set on the upper side (anti-air side).

  In this case, when the level of the lubricating liquid is above the stepped surface 11, the free pistons 6 and 6A are disposed in the lubricating liquid in contact with the stepped surface 11, but from the foreign matter and the flaw portion. When the lubricating liquid flows out and the liquid level falls below the stepped surface 11, the free pistons 6 and 6A are lifted to the liquid level of the lubricating liquid, and are in the same state as in the initial setting of one embodiment or other embodiments. It becomes.

  In the above embodiments, the movable range of the free pistons 6, 6 </ b> A is in the sliding gaps 30, 30 </ b> A, but is not limited thereto, and may be in the liquid reservoir 31.

  Further, the shape of the free pistons 6 and 6A is not limited to the above, and the shape can be selected as appropriate.

  Moreover, in the said embodiment, although the level | step difference surface 11 is formed in the internal peripheral surface of the outer tube 1, and the movement to the anti-air side of the free pistons 6 and 6A is controlled by this level | step difference surface 11, it does not necessarily have a level | step difference surface. 11 need not be provided, and the enlarged diameter portion 10 may not be provided. In this case, the outer diameters of the free pistons 6 and 6A may be appropriately changed so that the free pistons 6 and 6A can move in the lubrication gap 30 in the axial direction.

A Air chamber D Buffer F Suspension device body L Communication path 1 Outer tube 2 Inner tube 3 Cylindrical gap 4 Outer bearing 5 Seal member 6, 6A Free piston 7 Washer 8 Inner bearing 13 Groove 30, 30A Sliding gap 31 Liquid reservoir Chamber 32 Pockets 40, 41 Joint 50 Oil seal 51 Dust seal 70 Stopper 71 Tube

Claims (6)

An outer tube, an inner tube inserted in and out of the outer tube, an air chamber formed inside the outer tube and the inner tube and sealed while gas is compressed, the outer tube and the inner tube A cylindrical gap formed between the overlapping portions of the tubes, an outer bearing that is held on the inner periphery of the outer tube and is in sliding contact with the outer peripheral surface of the inner tube, and an outer air side of the outer tube of the outer tube. In the suspension device comprising an oil seal that is held in series with the outer bearing on the inner periphery, slidably contacts the outer peripheral surface of the inner tube, and closes the outside air side opening of the cylindrical gap.
The cylindrical gap contains the lubricating liquid and communicates with the air chamber through a hole formed in the inner tube. The cylindrical gap has a specific gravity lighter than the lubricating liquid, and A suspension device comprising a free piston capable of moving in a axial direction within a certain range of a cylindrical gap. The cylindrical gap is disposed between the outer bearing and the oil seal side of the outer bearing, and between the outer bearing and the oil seal, and communicates with the sliding gap via a communication path. A liquid storage chamber is formed,
The suspension device according to claim 1, wherein the free piston is provided in the sliding gap.   The suspension device according to claim 1 or 2, wherein the free piston is set to float on a liquid surface of the lubricating liquid at the time of initial setting.   The free piston is formed in an annular shape, so that when the free piston floats on the surface of the lubricating liquid, the free piston has no allowance for the inner tube and is not compressed by the outer tube. The suspension device according to claim 2 or 3, wherein the suspension device is set. The free piston is made of an annular elastic body, and an annular pocket is formed on the outer bearing side in the sliding gap,
The sectional area when the pocket is cut in the radial direction gradually decreases toward the outer bearing side, and movement of the free piston toward the outside air is restricted in the middle of the pocket. Suspension system.   5. The suspension device according to claim 4, wherein the free piston has a conical portion whose outer periphery is gradually reduced in diameter toward the outside air side.

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