JP4198555B2 - Seal structure - Google Patents

Description

  The present invention relates to, for example, an improvement in a seal portion structure embodied between a free piston accommodated in a front fork incorporating a damper and a cylindrical member whose outer periphery is in sliding contact with the inner periphery.

  It is a front fork that is mounted on the front wheel side of a motorcycle and absorbs the input to the front wheel of the motorcycle with a built-in damper, and by installing a free piston inside it, the internal pressure in the damper is guaranteed, and the front fork There is a proposal that enables a predetermined reaction force to be generated by a damper during a compression operation (see, for example, Patent Document 1).

  Therefore, according to this proposal, since it is possible to generate a predetermined reaction force by the damper during the compression operation of the front fork, it can be said that it is possible to maintain a good riding comfort in the two-wheeled vehicle, but for some reason, Therefore, there is a concern that the above-mentioned free piston prevents the so-called surplus oil accumulated in the damper from flowing out into a so-called reservoir in the front fork.

Therefore, in the above proposal, when surplus oil accumulates in the damper, the above-described free piston moves backward to make a so-called gap appear, and this surplus oil flows out to the reservoir. The reaction force is not increased more than necessary.
JP-A-6-147248 (Claims Claim 1, Paragraph 0004, FIG. 1)

  However, in the above proposal, the rod body in which the inner periphery of the free piston and the inner periphery of the free piston face each other when the free piston moves through a predetermined stroke for causing excess oil accumulated in the damper to flow into the reservoir. An annular gap that appears between the outer circumference of the rod body, i.e., an annular gap that appears between the outer circumference of the reduced diameter portion of the rod body, is used. Therefore, depending on the movement state of the free piston, there is a concern that the free piston may reverse while the excess oil cannot be completely discharged, and the excess oil may be trapped in the damper.

  Therefore, the applicant of the present application previously proposed in Japanese Patent Application No. 2003-079679, but an annular gap that appears between the outer periphery of the free piston and the inner periphery of the cylindrical member facing the outer periphery of the free piston, that is, In addition, it can be said that a configuration in which excess oil in the damper is allowed to flow out by utilizing an annular gap that appears between the expanded inner circumference of the cylindrical member is preferable because a larger flow path area can be secured. .

However, at this time, the seal member housed in the annular groove formed on the outer periphery of the free piston is rich in elasticity to ensure a tightening allowance for closely contacting the inner periphery with the bottom of the annular groove. Because it is made of material, when excess oil in the damper tries to pass through the annular gap that appears between the outer periphery of the free piston and the inner periphery of the cylindrical member, the pressure caused by this excess oil is Since it may act on the inner side of the seal member, the seal member is crushed so that the outer peripheral side of the seal member swells, and the outer periphery of the seal member is brought into close contact with the inner periphery of the cylindrical member. A situation will appear where the oil cannot pass between the outer periphery of the seal member and the inner periphery of the cylindrical member.

  As a result, not only may there be a risk that excess oil in the damper cannot flow into the reservoir, but the seal member remains in a crushed state, that is, the outer periphery of the seal member remains within the cylindrical member. When the free piston moves so as to be reversed while being in close contact with the circumference, the seal member is sandwiched between the inner circumference of the cylindrical member that should originally slide and the outer circumferential edge of the annular groove. Therefore, there is a concern that the sealing member cannot be expected to exhibit a predetermined function because the sealing member is damaged.

  The present invention was created in view of such a current situation, and the purpose of the invention is to ensure a predetermined sealing property, as well as avoid damage to the sealing member, Permanent use becomes possible, for example, between a free piston housed in a front fork and a cylindrical member whose outer periphery is in sliding contact with the inner periphery so as to enable pressure guarantee in the damper. The present invention relates to an improvement in a seal structure that is optimal for realization.

In order to achieve the above-described object, the means of the present invention includes a cylindrical member having an enlarged diameter portion on one side and a high-pressure side chamber that is movably accommodated in the cylindrical member. seal and having a bounding member defining on the low pressure side vessel chamber, the seal member which is housed in an annular recessed groove formed in the outer periphery of the bounding member is in sliding contact with the inner periphery of the tubular member In the structure, a flow path for communicating the annular groove with the low-pressure side chamber is formed in the defining member, the defining member moves in the direction of the bulging portion, and the sealing member reaches the bulging portion. The oil in the high-pressure side chamber is caused to flow out from the annular groove to the low-pressure side chamber through the flow path, and the seal member is prevented from expanding by the internal pressure of the annular groove. It is characterized by.

  In the second aspect of the present invention, a flow passage that allows communication between the annular groove and the high-pressure side chamber is formed in a thick portion between the annular groove and the end surface facing the high-pressure side chamber in the defining member. Even at this time, it is preferable that the flow path is formed of a communication hole opened in a direction along the moving direction of the defining member.

  According to a third aspect of the present invention, there is provided a flow passage that allows communication between the annular groove and the high-pressure side chamber on the outer periphery of the thick portion between the annular groove and the end surface facing the high-pressure chamber in the defining member. In this case, it is preferable that the flow path is formed of a communication groove opened in a direction along the moving direction of the defining member.

According to the present invention, the following effects can be obtained.
According to the invention of claim 1, when the defining member moves in the cylindrical member and the seal member reaches the inside of the expanded diameter portion of the cylindrical member, the outer periphery of the defining member is Oil flows into the annular groove through the space between the inner periphery of the tubular member, but the pressure in the annular groove acting on the inner periphery of the seal member is released from the flow path to the low pressure side chamber. As a result, the pressure action for expanding the sealing member does not occur, and the sealing member itself is not sandwiched between the inner periphery of the expanding portion and the outer periphery of the defining member.
Therefore, the oil flows out to the low-pressure side chamber through the inner circumference of the expanded diameter portion of the cylindrical member and the outer circumference side of the seal member.
As a result, even if the sealing member is formed of a material rich in elasticity from the viewpoint of securing the tightening allowance and has a property of easily expanding, the seal member is moved when the defining member moves in a so-called reverse manner in the cylindrical member. The member is not sandwiched between the inner periphery of the cylindrical member and the outer peripheral side edge of the annular groove, and therefore the predetermined function of the seal member is made permanent without causing damage to the seal member. It is possible to make it manifest.

  And in invention of Claim 2 and Claim 3, a flow path is formed in the thick part by the side of the defining member facing the high voltage | pressure side container, or a flow path is formed in the outer periphery of a thick part. Therefore, the oil from the high-pressure side chamber is guided directly into the annular groove formed in the defining member through this flow path. The efficiency of outflow to the side chamber will be improved.

  As a result, according to the present invention, it is possible to guarantee a predetermined sealing property, as well as to prevent damage to the sealing member, and to use it permanently, for example, to ensure pressure in a damper Therefore, it is optimal to be realized between a free piston housed in the front fork and a cylindrical member whose outer periphery is in sliding contact with the inner periphery.

The present invention will be described below based on the illustrated embodiments .
As shown in FIGS. 1 and 2, the basic structure of the present invention is a cylindrical member 2 having an enlarged diameter portion 21 on one side, and the cylindrical member 2 is movably accommodated in the cylindrical member 2. 2 has a free piston 1 as an defining member that defines a high-pressure side chamber R1 and a low-pressure side chamber R2, and is housed in an annular groove 11 formed on the outer periphery of the free piston 1. This is a seal structure in which the seal member 3 is in sliding contact with the inner periphery of the tubular member 2.
In the present invention, the free piston 2 is further provided with a communication hole 13 as a flow path for communicating the annular groove 11 to the low-pressure side chamber R2 in the free piston 2, and the free piston 2 moves in the direction of the expanded diameter portion 21. When the seal member 3 reaches the inside of the enlarged diameter portion 21, the oil in the high-pressure side chamber flows out from the annular groove 11 into the low-pressure side chamber R2 through the communication hole 13, and the annular recess. It is characterized in that the diameter of the seal member 3 is prevented from expanding due to the internal pressure of the groove 11.

  To explain a little, the front fork is not shown in the figure, but in this embodiment, an inner tube, which is a vehicle body side tube, is inserted into an outer tube, which is a wheel side tube, so as to be able to protrude and retract. It is assumed that a predetermined damping action is exerted by the damper during the expansion and contraction operation of the front fork in which the tube appears and disappears.

  In this embodiment, the damper is set upside down, and the cylinder body serving as the upper member is suspended from the shaft core portion of the inner tube, and the rod body serving as the lower member is the outer tube. It is assumed that a predetermined damping force is generated by the damping valve during expansion and contraction of the damper in which the rod body protrudes and retracts with respect to the cylinder body.

  In this embodiment, the damping valve is disposed in the piston portion that is connected to the tip of the rod body and moves in the cylinder body, and is disposed in the base valve portion that is disposed inside the bottom portion of the cylinder body. When the expansion side oil chamber and the pressure side oil chamber defined by the piston portion communicate with each other in the cylinder body, and when the pressure side oil chamber and the so-called reservoir side beyond the base valve portion communicate with each other In addition, each of them generates a damping force having a predetermined magnitude.

  Incidentally, the outside of the damper, that is, the inside of the outer tube and the inner tube is used as a reservoir, and excess oil in the damper, that is, from a high-pressure side chamber R1, which will be described later, communicates with the base valve portion. The oil is allowed to flow in through a low pressure side chamber R2 and a later-described expanded diameter cavity R communicating with the low pressure side chamber R2 (see FIG. 2).

  By the way, as shown in FIGS. 1 and 2, the seal portion structure in the present invention includes a cylindrical member 2, a free piston 1, and a seal member 3, and the cylindrical member 2 is free. The piston 1 has an expanded diameter portion 21 that enables the high-pressure side chamber R1 and the low-pressure side chamber R2 to be defined and forms an expanded space R that communicates with the low-pressure side chamber R2.

  The free piston 1 is movably accommodated inside the tubular member 2 and defines the inside of the tubular member 2 into a high-pressure side chamber R1 and a low-pressure side chamber R2. Is accommodated in an annular groove 11 formed on the outer periphery of the free piston 1, and the outer periphery is in sliding contact with the inner periphery of the cylindrical member 2.

  To explain a little, the cylindrical member 2 is integrally connected to the bottom portion constituting the cylinder body in the above-described damper, that is, the bottom portion having the base valve portion on the inside, although not shown, in this embodiment. In this case, it is formed of a portion connected to the inner tube in a liquid-tight state.

  If the cylindrical member 2 is a portion integrally connected to the bottom end of the cylinder body in the damper, as described above, the damper has the base valve portion, and thus the high-pressure side chamber R1 described above. Is defined between the base valve portion and the free piston 1 opposed thereto.

  In contrast, the low-pressure side chamber R2 is defined behind the free piston 1, and at this time, the low-pressure side chamber R2 is not shown in FIG. It is assumed that the expansion space R (see FIG. 2) which is the inside of the diameter portion 21 (see FIG. 2) communicates.

  In addition, a communication hole 22 that penetrates the wall thickness of the expanded diameter portion 21 is opened in the expanded diameter portion 21, and communication between the inside and the outside of the expanded diameter portion 21 is allowed. Therefore, the oil that has flowed out of the high-pressure side chamber R1 into the low-pressure side chamber R2 can flow out of the enlarged diameter portion 21 through the communication hole 22.

  Incidentally, the outer side of the expanded diameter portion 21, that is, the outer side of the cylindrical member 2, is a reservoir defined inside the front fork, which is the outer side of the damper, as described above.

  When the cylindrical member 2 is integrally connected to the bottom portion of the cylinder body in the damper, in many cases, a portion corresponding to the cylindrical member is formed at the time of forming the cylinder body. At this time, in this embodiment, the above-mentioned expanded diameter portion 21 will also be formed.

  On the other hand, in this seal portion structure, the annular groove 11 and the low-pressure side chamber R2 are formed in the thick portion 12 between the annular groove 11 in the free piston 1 and the end surface facing the low-pressure side chamber R2. When the free piston 1 moves in the tubular member 2 and the seal member 3 reaches the expanded diameter portion 21 of the tubular member 2, the communication hole 13 is formed. It is assumed that the outer periphery of the member 3 is separated from the inner periphery of the enlarged diameter portion 21 of the tubular member 2 to allow communication with the low-pressure side chamber R2 in the annular groove 11.

That is, when the free piston 1 moves in the cylindrical member 2 and the seal member 3 reaches the inside of the expanded diameter portion 21 of the cylindrical member 2, the outer periphery of the free piston 1 and the cylindrical shape are formed from the high-pressure side chamber R1. The oil that has flowed into the annular groove 11 through the space between the inner periphery of the member 2 is between the inner periphery of the seal member 3 and the bottom of the annular groove 11, as indicated by a broken line arrow a in FIG. 2. It flows into the communicating hole 13 through the leakage gap and flows out from the communicating hole 13 to the low-pressure side chamber R2 . At this time, the pressure in the annular groove 11 acting on the inner peripheral side of the seal member 3 is released from the communication hole 13 to the low-pressure side chamber R2, and as a result, the pressure action that expands the diameter of the seal member. The seal member is not sandwiched between the inner periphery of the enlarged diameter portion and the outer periphery of the defining member.
Therefore, the oil flows out to the low-pressure side chamber R <b> 2 side through the inner periphery of the enlarged diameter portion 21 in the cylindrical member 2 and the outer periphery side of the seal member 3.
As a result, even if the seal member 3 is formed of a material rich in elasticity from the viewpoint of securing the tightening allowance and has the property of being easily expanded if there is no restriction, the free piston 1 reverses the inside of the cylindrical member 2 so-called. When moving, the seal member 3 is not sandwiched between the inner periphery of the tubular member 2 and the outer peripheral side edge of the annular groove 11, and therefore the seal member 3 is not damaged. Thus, the predetermined function of the seal member 3 can be made permanent.

  As a result, even if the seal member 3 is formed of a material rich in elasticity from the viewpoint of securing the tightening allowance and has the property of being easily expanded if there is no restriction, the free piston 1 reverses the inside of the tubular member 2 so-called. When moving, the seal member 3 is not sandwiched between the inner periphery of the tubular member 2 and the outer peripheral side edge of the annular groove 11, and therefore the seal member 3 is not damaged. Thus, the predetermined function of the seal member 3 can be made permanent.

  In view of the above, in this seal portion structure, the oil that has flowed into the annular groove 11 from the high-pressure side chamber R1 initially becomes between the inner periphery of the seal member 3 and the bottom of the annular groove 11. Since it suffices to pass through the leakage gap, as long as the flow on the inner peripheral side of the seal member 3 is not obstructed, as shown in FIG. 3, the annular groove 11 and the high-pressure side chamber R1 in the free piston 1 A flow allowing the annular groove 11 and the high-pressure side chamber R1 to communicate with the thick portion 14 between the opposing end surfaces, and allowing the oil to flow into the annular groove 11 from the high-pressure side chamber R1. A communication hole 15 may be provided, and as shown in FIG. 4, a flow path that allows the oil from the high-pressure side chamber R <b> 1 to be guided to the annular groove 11 on the outer periphery of the thick portion 14. It can be said that the communication groove 16 may be provided.

  Incidentally, at this time, it goes without saying that the axial direction of the communication hole 15 and the communication groove 16 does not have to coincide with the axial direction of the communication hole 13.

  Therefore, in the case of the embodiment shown in FIGS. 3 and 4, the oil from the high-pressure side chamber R <b> 1 is directly guided into the annular groove 11 through the communication hole 15 and the communication groove 16. Accordingly, the efficiency of oil flow from the high-pressure side chamber R1 to the low-pressure side chamber R2 is improved.

  In the above description, the defining member is composed of the free piston 1, but from the viewpoint of the present invention, although not shown, the defining member may be a piston connected to the piston rod. Of course, the effect of the case is not different.

It is a figure which shows in principle the seal part structure by this invention. It is a figure which shows the operating state of the seal | sticker part structure of FIG. 1 similarly to FIG. It is a figure which shows the seal | sticker part structure by other embodiment similarly to FIG. It is a figure which shows the seal | sticker part structure by other embodiment similarly to FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Free piston as defining member 2 Cylindrical member 3 Seal member 11 Annular groove 12, 14 Thick part 13, 15 Communication hole which is flow path
16 channels of communication groove 21 expanded diameter portion 22 communication hole
R upset spatial R1 pressure side vessel chamber R2 the low pressure side vessel chamber

Claims (3)

A cylindrical member having an enlarged diameter portion on one side, and a defining member that is movably accommodated in the cylindrical member and defines the inside of the cylindrical member into a high-pressure side chamber and a low-pressure side chamber the a, in the sealing structure sealing member that is accommodated in an annular recessed groove formed in the outer periphery of the bounding member is in sliding contact with the inner periphery of the tubular member, the low pressure of the annular groove in the bounding member A flow path communicating with the side chamber is formed, and when the defining member moves in the direction of the enlarged diameter portion and the seal member reaches the inside of the enlarged diameter portion, the oil in the high-pressure side chamber is removed from the annular recess. A seal portion structure that prevents the seal member from flowing out from the groove through the flow path to the low-pressure side chamber and expanding the seal member with the internal pressure of the annular groove. The flow path which permits the communication between the inside of an annular groove and a high voltage | pressure side is formed in the thick part between the annular groove and the end surface which opposes a high voltage | pressure side container in an defining member. Seal structure A flow passage that allows communication between the annular groove and the high-pressure side chamber is formed on the outer periphery of the thick portion between the annular groove and the end surface facing the high-pressure chamber in the defining member. 1. Seal part structure according to

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