JP4405901B2 - Hydraulic shock absorber - Google Patents

Description

  The present invention relates to a hydraulic shock absorber, and more particularly to an improvement of a hydraulic shock absorber that is mounted on a front wheel side of a two-wheeled vehicle and is used for a front fork that absorbs road surface vibrations input to the front wheel.

  There have been various proposals for a hydraulic shock absorber used for a front fork that is mounted on the front wheel side of a two-wheeled vehicle and absorbs road surface vibration input to the front wheel. In the proposal of the disclosure, it is assumed that the fork main body constituting the front fork, that is, the shaft part of the fork main body, which is a telescopic body in which the inner cylinder is inserted and retracted into the outer cylinder, has a damper portion. Yes.

  The damper portion is formed into an upright type in which a rod body, which is an upper member, is inserted in a retractable manner relative to a cylinder body, which is a lower member. In other words, the rod body appears and disappears from the cylinder body, and a predetermined damping force is generated at the damping force generation section in the damper section.

  On the other hand, in the proposal disclosed in Patent Document 1, the base valve portion is provided in the bottom end portion of the cylinder body constituting the damper portion, and the oil chamber in the cylinder body is interposed via the base valve portion. And a reservoir chamber outside the damper section, and a free piston as a partition member is provided between the base valve section and the reservoir chamber, and the free piston slides between the free piston and the base valve section. The oil amount compensation chamber is made wide by dynamic movement.

  The free piston is allowed to flow in and out of hydraulic oil corresponding to the rod volume with respect to the oil amount compensation chamber by sliding between the free piston and the oil chamber in the cylinder body in the region of the normal expansion / contraction stroke in the damper portion. Yes.

  In addition, this free piston is, for example, when there is so-called surplus working oil in the cylinder body due to pressure accumulation in the oil chamber of the cylinder body or volume expansion accompanying an increase in oil temperature, etc. The oil amount compensation chamber moves, that is, slides to the reservoir chamber via a flow path that appears between the inner periphery of the cylinder body and the outer periphery of the free piston. To release.

Therefore, according to the proposal disclosed in Patent Document 1, since the hydraulic pressure in the oil chamber in the cylinder body can be always kept normal, it is possible to generate the damping force generated by the damping force generation unit in the damper unit as set. It becomes possible.
Japanese Patent No. 3207967 (Claims Claims 1, Paragraphs 0009, 0019, 0021, FIGS. 1 and 3)

  However, in the proposal disclosed in Patent Document 1 described above, there is a possibility that it is pointed out that there are the following problems.

  In other words, the above proposal uses a flow path that appears between the inner periphery of the cylinder body and the outer periphery of the free piston when the free piston is slid to release the excess hydraulic oil in the cylinder body to the reservoir chamber. If so.

  At this time, in order to form the flow path, a so-called retreating part having a concave shape is formed on the inner periphery of the cylinder body, and this flow path appears when the free piston is aimed at the retreating part. .

  Therefore, when the free piston is aimed at the retracted portion, the seal interposed on the outer periphery of the free piston is separated from the inner periphery of the cylinder body and expands to face the retracted portion. When the so-called return after the free piston is brought into sliding contact with the inner periphery of the cylinder body, the seal passes through the boundary portion between the inner periphery and the retracted portion of the cylinder body and is contracted.

  As a result, if the free piston is repeatedly slid repeatedly, the seal reciprocates at the boundary between the inner periphery of the cylinder body and the retreating portion while repeating so-called expansion and contraction, and the base valve portion by the free piston is damaged. There is a risk that the definition during the period, that is, the definition of the oil compensation chamber will not be guaranteed.

  The present invention was devised in view of such a current situation, and the object of the present invention is to provide a front fork so that a predetermined oil amount compensation function by the oil amount compensation chamber can be exerted permanently. This is to provide a hydraulic shock absorber that is optimal for use in the field and is expected to be expected to improve its versatility.

  In order to achieve the above-described object, the structure of the hydraulic shock absorber according to the present invention is basically as set forth in claim 1, wherein the inner cylinder is inserted into the outer cylinder so that the inner cylinder can protrude and retract. In addition to having an upright damper portion through which a rod body, which is an upper member, can be inserted and retracted with respect to a cylinder body, which is a lower member, an oil chamber and a cylinder in the cylinder body inside or outside the damper portion In a hydraulic shock absorber having a free piston that defines a reservoir chamber outside the body, the free piston slides the outer periphery on the inner periphery of the cylinder body, or the inner cylinder of the fork body or the inner periphery of the outer cylinder. A partition body and an operation check valve disposed in the partition body. The operation check valve maintains a closed state by hydraulic pressure in an oil chamber in the cylinder body, Chamber to be operate check valve is opening operation interferes with the stopper portion which is opposed to when the partition wall body is high pressure is lowest sliding.

  Preferably, in claim 2, when the oil chamber in the cylinder body has a negative pressure tendency as compared with the reservoir chamber outside the cylinder body, the operation check valve is opened to operate the cylinder of the hydraulic oil from the reservoir chamber. Suppose that it is allowed to flow into the oil chamber in the body.

  Therefore, in the invention of claim 1, the operation check distributed in the partition body constituting the free piston by moving the free piston in the damper portion with a large stroke, that is, by sliding most. If the valve interferes with the stopper portion, it is forcibly opened by an external input.

  Therefore, the seal is separated from the inner periphery of the cylinder body as compared with the case where the flow path is formed by separating the seal from the inner periphery of the cylinder body and facing the recessed receding portion formed on the inner periphery of the cylinder body. The situation of passing through the boundary with the retreating part is not expressed, and since the expansion and contraction of the seal is not repeated, it becomes possible to prevent the seal from being damaged, and the function of the seal can be guaranteed permanently. It will be.

  As a result, according to the hydraulic shock absorber of the present invention, the predetermined oil amount compensation function in the oil amount compensation chamber defined by the free piston is permanently guaranteed in the front fork without fear of sealing pain. Will get.

  In the invention of claim 2, when the oil chamber in the cylinder body tends to have a negative pressure as compared with the reservoir chamber side, the operation check valve is released and the hydraulic oil from the reservoir chamber is released. Therefore, the shortage of hydraulic oil is not expressed in the oil chamber in the cylinder body, and the damping force generated in the damping force generation unit in the cylinder body, that is, the damping force in the damper unit is generated as set. It will be.

  In the following, the present invention will be described based on the illustrated embodiment. In the hydraulic shock absorber according to the present invention, as shown in FIG. 1 as a principle diagram, first, the inner cylinder T2 can appear and disappear in the outer cylinder T1. It is assumed that the damper portion is housed in the shaft core portion of the fork main body, which is a stretchable body inserted through the shaft.

  At this time, the fork main body is set to an inverted type in which the outer cylinder T1 is a vehicle body side member while the inner cylinder T2 is a wheel side member as shown in FIG. As shown, the outer cylinder T1 is set as a wheel side member, whereas the inner cylinder T2 is set as an upright type as a vehicle body side member. Of course, it is not a limiting condition for the realization.

  Incidentally, in each fork main body shown in FIGS. 1 and 2 configured as described above, the fork main body is energized in the so-called extension direction by the suspension spring S accommodated therein.

  Next, it is assumed that the damper portion is set to be an upright type in which a rod body 2 as an upper member is inserted into a cylinder body 1 as a lower member so that the rod body 2 can protrude and retract. In the place shown in FIG. 1, it stands up in the axial part of the inner cylinder T2, and in the place shown in FIG. 2, it stands up in the axial part of the outer cylinder T1.

  Further, the rod body 2 is suspended from the shaft core portion of the outer cylinder T1 as shown in FIG. 1, and the rod body 2 is suspended from the shaft core portion of the inner cylinder T2 as shown in FIG. 2, the base end side which is the lower end side is inserted into the cylinder body 1 so as to be able to appear and retract.

  The damper portion has a free piston P that defines an oil chamber in the cylinder body 1 and a reservoir chamber R side outside the cylinder body 1, and in the place shown in FIG. It is assumed that the piston P is accommodated inside the bottom end portion of the cylinder body 1 and is accommodated in the reservoir chamber R outside the cylinder body 1 as shown in FIG.

  Incidentally, in the damper portion shown in FIGS. 1 and 2, the piston portion 3 integrally held at the base end portion which is the lower end portion in the drawing of the rod body 2 is slidably accommodated in the cylinder body 1. It is assumed that the rod-side oil chamber R1 and the piston-side oil chamber R2 are defined in the cylinder body 1 by the piston portion 3.

  In each damper portion, the rod-side oil chamber R1 and the piston-side oil chamber R2 are mutually connected via a damping valve 3a disposed in the piston portion 3 and an extension-side check valve 3b parallel to the damping valve 3a. To communicate with.

  Each of the damper portions has a base valve portion 4 inside the bottom end portion of the cylinder body 1, and a damping valve 4a disposed in the base valve portion 4 and the damping valve 4a in parallel. The piston side oil chamber R2 and the reservoir chamber R side are allowed to communicate with each other via the extending side check valve 4b.

  Therefore, in each of the damper parts formed as described above, when the fork main body expands and contracts, the rod body 2 appears and disappears in synchronization with the cylinder body 1 and expands and contracts.

  In each damper portion, for example, when the piston portion 3 is in a contracting operation in which the piston portion 3 descends in the cylinder body 1, the working oil from the piston-side oil chamber R <b> 2 is connected to the extension side check valve 3 b disposed in the piston portion 3. And flows out to the reservoir chamber R side through the damping valve 4a disposed in the base valve portion 4 and the hydraulic oil passes through the damping valve 4a. The compression side damping force is generated.

  In each of the damper portions, contrary to the above, during the extension operation in which the piston portion 3 moves up in the cylinder body 1, the hydraulic oil from the rod side oil chamber R1 is distributed to the piston portion 3 and the damping valve 3a. Then, the hydraulic oil flows out through the damping valve 3a and a predetermined extension side damping force is generated.

  At this time, in each damper portion, the hydraulic oil that is insufficient in the piston-side oil chamber R2 due to the retraction of the piston portion 3 passes from the reservoir chamber R side to the base valve portion 4 via the pressure-side check valve 4b. To be replenished.

  At this time, the hydraulic fluid that flows from the reservoir chamber R side into the piston-side oil chamber R2 in the cylinder body 1 via the base valve portion 4 becomes hydraulic fluid on the lower bottom side in the reservoir chamber R, and therefore the reservoir chamber R Therefore, the damping force generated in the damper portion is easily stabilized.

  On the other hand, when the damper portion is formed as described above, in the present invention, the free piston P is, as shown in FIG. Are defined on the so-called upstream side base valve portion 4 side and on the downstream side reservoir chamber R side.

  In addition, the free piston P includes a chamber portion formed by a lower portion and a lower end portion of the reservoir chamber R in the figure of the base valve portion 4 as shown in FIG. The upper part in the drawing, that is, the reservoir chamber R part is defined.

  At this time, as shown in FIG. 1, the chamber portion defined above the free piston P and between the base valve portion 4 is the oil amount compensation chamber A according to the present invention. 2, it is assumed that the volume chamber portion formed by the lower portion of the base valve portion 4 and the lower end portion of the reservoir chamber R is an oil amount compensation chamber A. The oil amount compensation chamber A is the base valve portion 4. It communicates with the piston side oil chamber R2 in the cylinder body 1 via the cylinder, and communicates with the reservoir chamber R outside the damper portion via the operation check valve 6 that opens, as will be described later.

  As shown in FIG. 1, the free pistons P arranged as described above are arranged in an annular partition wall 5 in which the outer periphery slides on the inner periphery of the cylinder body 1, and the partition body 5. The operation check valve 6 is maintained in a closed state by the hydraulic pressure in the oil chamber in the cylinder body 1, that is, the hydraulic pressure in the cylinder body 1, and the hydraulic pressure in the cylinder body 1 is maintained. When the pressure is increased and the partition wall 5 is in the lowest sliding position in the drawing, it interferes with the stopper portion 7 on which the operation check valve 6 is opposed, that is, with the stopper portion 7 fixed on the bottom surface of the inner cylinder T2. It is said that it will open.

  In the free piston P shown in FIG. 2, the outer periphery of the annular partition wall 5 is in sliding contact with the inner periphery of the outer cylinder T <b> 1 forming the fork main body, and is operated in the partition body 5. The check valve 6 is kept closed by the hydraulic pressure in the cylinder body 1 and the operation check valve 6 is opposed at the time of the maximum sliding when the hydraulic pressure in the cylinder body 1 is increased and the partition wall body 5 rises most in the drawing. It is assumed that the opening operation is performed by interfering with the stopper portion 7 arranged, that is, in the reservoir chamber R and being fixed to the outer periphery of the cylinder body 1.

  The operation check valve 6 is formed so as to be kept closed by the hydraulic pressure in the cylinder body 1 as described above, while the oil chamber in the cylinder body 1 is in the reservoir chamber R outside the cylinder body 1. When the pressure tends to be negative, the opening operation is performed to allow the hydraulic oil from the reservoir chamber R to flow into the oil chamber in the cylinder body 1.

  At this time, the operation check valve 6 may be of any configuration as long as it is configured to allow the above-described closed state and opening operation. For example, FIG. 3, FIG. 4 and FIG. As shown, the operation check valve 6 is so-called hydraulic pressure on the oil chamber side in the cylinder body 1 on the rear side with the pointed end facing the stopper portion 7, that is, specifically, hydraulic pressure in the oil amount compensation chamber A. It is assumed that a poppet body 61 that is a valve body that maintains a closed state, that is, a seated state on a valve seat portion (not shown), is provided. In addition, in FIG. The valve body that maintains the above-mentioned closed state with the oil pressure in the oil chamber in the cylinder body 1 on the back side, that is, specifically, the oil pressure in the oil amount compensation chamber A while facing the It has become a needle body 62.

  Further, in each of the operation check valves 6, the poppet body 61 and the needle body 62, which are valve bodies, are arranged on the back side of each so as to seat the poppet body 61 and the needle body 62 on the valve seat portion. The urging spring 63 is urged in the so-called forward direction.

  At this time, the spring force in the biasing spring 63 is such that the hydraulic pressure in the cylinder body 1, that is, specifically, the hydraulic pressure in the oil amount compensation chamber A tends to be negative compared to the reservoir chamber R side. Further, the poppet body 61 and the needle body 62 which are valve bodies overcome the spring force of the urging spring 63 and move backward to connect the oil amount compensation chamber A to the oil chamber in the cylinder body 1, that is, from the reservoir chamber R. It is set to allow the inflow of hydraulic oil.

  Therefore, in each of the operation check valves 6 formed as described above, when the partition body 5 constituting the free piston P descends with a large stroke in FIGS. 3, 4, and 5, In FIG. 6, when ascending with a large stroke, that is, when sliding most, the poppet body 61 and the needle body 62 as the valve bodies interfere with the stopper portion 7 and are forcibly retracted. When this occurs, a gap appears between the valve body and the valve seat portion, allowing hydraulic fluid to flow.

  By the way, when the above gap appears between the valve body and the valve seat portion, a gap serving as a flow path is formed between the outer periphery of the partition body 5 and the inner periphery of the cylinder body 1 or the inner periphery of the inner cylinder T2. Since it does not appear, even if a seal is interposed on the outer periphery of the partition body 5, compared to the proposal disclosed in Patent Document 1 described above, this seal does not get over the stepped portion, Since the expansion and contraction of the seal is not repeated, there is no need to worry that the seal is damaged and the definition function in the free piston P is lowered, and the oil amount compensation function in the oil amount compensation chamber A can be permanently secured. become.

  The partition body 5 slides most when the so-called surplus hydraulic oil is present in the cylinder body 1 due to pressure accumulation in the oil chamber in the cylinder body 1 or an increase in the oil temperature. Interferes with the stopper portion 7 and a so-called flow path is formed, so that excess hydraulic oil in the cylinder body 1 is released to the reservoir chamber R, and this excess hydraulic oil is released in the cylinder body 1. Therefore, the hydraulic pressure in the oil chamber in the cylinder body 1 is maintained in a normal state.

  When the free piston P has the operation check valve 6 inside the partition body 5 in the above place, it means that the free piston P is formed in a divided structure. Since the outer periphery of the body 5 is in sliding contact with the inner periphery of the cylinder body 1 and the inner periphery of the inner cylinder T2, the operation check valve 6 is in sliding contact with the outer periphery of the center rod 41 and the outer periphery of the cylinder body 1. Sliding resistance is small and sliding performance is ensured even if precise concentricity between the inner circumference and the outer circumference of the center rod 41 or between the outer circumference of the cylinder body 1 and the inner circumference of the inner cylinder T2 is not ensured. This is advantageous.

  In addition, in the present invention, the operation check valve 6 can freely move with respect to the partition body 5, and therefore, when the inside of the cylinder body 1 tends to have a so-called negative pressure, the operation check valve 6 is operated to be opened outside the cylinder body 1. That is, since the inflow of the hydraulic oil from the reservoir chamber R into the cylinder body 1 is allowed, the inflow of the hydraulic oil into the cylinder body 1 in which a so-called vacuum phenomenon is caused, for example, the rod body 2 with respect to the cylinder body 1 This is advantageous in that the vacuum phenomenon in the cylinder body 1 can be quickly eliminated as compared with the case where the operation only depends on the movement operation.

  The above is the characteristic operation state and effect of the free piston P according to the present invention, and the specific configuration is as follows.

  That is, for example, in the places shown in FIGS. 3, 4, and 6, the poppet body 61 constituting the operation check valve 6 is formed in the axial core portion of the partition body 5, that is, in the annular partition body 5. It is supposed that it is arranged to be movable inside, that is, to be able to move up and down.

  At this time, as shown in FIG. 3 and FIG. 4, the partition wall 5 is interposed on the outer side of the center rod 41 that stands on the shaft core portion of the cylinder body 1 and holds the base valve portion 4 at the upper end portion. Of course, the poppet body 61 disposed inside the partition body 5 is configured such that the inner periphery thereof is in sliding contact with the outer periphery of the cylinder body 1.

  The poppet body 61 shown in FIGS. 3 and 4 embodies a so-called closed state when seated on the valve seat portion formed in the partition wall body 5, and at this time, the poppet body 61 shown in FIG. It is assumed that the generation of so-called noise is prevented by sitting on the cushioning material 51 disposed in the valve seat portion.

  On the other hand, in the place shown in FIG. 5, the needle body 62, which is a valve body, is arranged on the outer peripheral side portion of the partition wall body 5, that is, is incorporated in the partition wall body 5.

  Thus, by incorporating the needle body 62 as a valve body into the partition body 5, the free piston P has a poppet body 61 as a valve body inside the partition body 5. Assembly can be made possible.

  In the place shown in FIG. 6, since the free piston P is arranged outside the cylinder body 1 in the damper portion, compared to the case where the free piston P is arranged inside the cylinder body 1. There is an advantage that not only the machining for the cylinder body 1 can be reduced, but also the cylinder body 1 can be shortened.

  Incidentally, in the place shown in FIG. 6, the free piston P is accommodated in a case body C formed of a cylindrical body arranged inside the inner cylinder T2, and the outer periphery of the partition body 5 is the case body. Although it is supposed that the inner periphery of C is slidably contacted, if the present invention intends, the arrangement of the case body C is omitted, and the outer periphery of the free piston P is directly slidably contacted with the inner periphery of the inner cylinder T2. It may be.

It is a longitudinal cross-sectional view which shows an example of the hydraulic shock absorber by this invention in principle. It is a longitudinal cross-sectional view which shows in principle the other example of the hydraulic shock absorber by this invention. It is a fragmentary longitudinal cross-sectional view which expands and shows one Embodiment of a free piston. It is a figure which shows other embodiment of a free piston similarly to FIG. It is a figure which shows other embodiment of a free piston similarly to FIG. It is a figure which shows other embodiment of a free piston similarly to FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cylinder body 2 Rod body 3 Piston 4 Base valve part 5 Partition body 5a Outer peripheral part 6 Operate check valve 7 Stopper part 51 Buffer material 61 Poppet body 62 Needle body A Oil amount compensation chamber P Free piston R Reservoir chamber R1 Rod side oil chamber R2 Piston side oil chamber T1 Outer cylinder T2 Inner cylinder

Claims (7)

The upright rod body which is an upper member with respect to the cylinder body when the inner cylinder into the outer cylinder are lower member in the axial core portion of the fork body ing is capable inserted retractable is inserted in retractably A hydraulic shock absorber having a damper portion and a free piston that defines an oil chamber inside the cylinder body and a reservoir chamber outside the cylinder body inside or outside the damper portion. Or a partition body that slidably contacts the inner periphery of the inner cylinder or outer cylinder that constitutes the fork main body, and an operation check valve disposed in the partition body. Stopper part that maintains the closed state by the oil pressure in the oil chamber, and the operation check valve is arranged oppositely when the oil chamber in the cylinder body is pressurized and the partition wall slides most. Hydraulic shock absorber, characterized in that interference to opening operation When the oil chamber in the cylinder body tends to have a negative pressure compared to the reservoir chamber outside the cylinder body, the operation check valve is opened to allow the operating oil from the reservoir chamber to flow into the oil chamber in the cylinder body. The hydraulic shock absorber according to claim 1. 2. The hydraulic shock absorber according to claim 1, wherein the operation check valve is disposed on the partition wall under a separation structure or under an integral structure. 2. The hydraulic shock absorber according to claim 1, wherein the operation check valve has a poppet body or a needle body that maintains a closed state by oil pressure in an oil chamber in the cylinder body on the rear side with a tip end facing the stopper portion. The poppet body that constitutes the operating check valve stands on the shaft core portion of the cylinder body while being arranged on the shaft core portion of the partition wall body, and on the outer periphery of the center rod that holds the base valve portion on the upper end portion or on the outer periphery of the cylinder body The hydraulic shock absorber according to claim 4, wherein the hydraulic shock absorber is in sliding contact. The shock absorbing material which accept | permits the contact of the tip part in a poppet body is interposed between the poppet body which comprises an operate check valve, and the valve seat part which seats the tip part in this poppet body. Hydraulic shock absorber The hydraulic shock absorber according to claim 4, wherein the needle body constituting the operate check valve is disposed on the outer peripheral side portion of the partition wall body.

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