JP4584844B2 - Shock absorber valve structure and shock absorber - Google Patents

Description

  The present invention relates to an improved shock absorber valve structure and shock absorber.

  Conventionally, this kind of shock absorber valve structure is embodied in, for example, a piston portion of a shock absorber for a vehicle, and an annular leaf valve is laminated on the outlet end of a port provided in the piston portion. A valve that opens and closes a port is known.

  In particular, in the above-described shock absorber valve structure in which the inner periphery of the leaf valve is fixedly supported and the port is opened and closed by bending the outer peripheral side, the damping force in the medium and high speed regions becomes too large in the vehicle. In order to solve this problem, the inner circumference of the leaf valve L is not fixedly supported and the inner circumference of the leaf valve L is screwed to the piston rod R as shown in FIG. Then, a valve structure of a shock absorber in which the back surface of the leaf valve L is urged by the spring S through the main valve M by being brought into sliding contact with the outer periphery of a cylindrical piston nut N or the like that fixes the piston P has been proposed. As shown in the figure, it is embodied in the expansion side damping valve of the shock absorber (see, for example, Patent Document 1).

In the shock absorber to which this valve structure is applied, as shown in the figure, when the piston speed when the piston P moves upward is in a low speed region, the outer peripheral side of the leaf valve L is stacked on the leaf valve L. Since it bends with the contact part as a fulcrum, it exhibits damping characteristics almost the same as a valve structure in which the inner periphery is fixedly supported, and when the piston speed reaches the middle-high speed range, the pressure of the hydraulic oil passing through the port Po Acts on the leaf valve L, and the leaf valve L lifts in the axial direction from the piston P together with the main valve M against the urging force of the spring S, so that the inner periphery is fixedly supported. Compared to the valve structure, the flow path area is increased and the damping force is suppressed from being excessive, thereby improving the riding comfort in the vehicle.
Japanese Patent Laid-Open No. 9-291196 (FIG. 1)

  However, in the proposed valve structure and the shock absorber to which the valve structure is applied as described above, although it is a useful technique in terms of improving the ride comfort in the vehicle, there is a possibility that it is pointed out that there are the following problems. is there.

  This is because, as described above, when the piston speed when the piston P moves downward in the drawing reaches the medium-high speed region, the leaf valve L moves backward from the piston P in the axial direction, and lifts from there. When the moving direction reverses and starts moving upward in the figure, the force that has pushed up the leaf valve L by the hydraulic oil until then decreases or disappears, so the leaf valve L tries to return to the position where it abuts on the piston P. When the lifted leaf valve L returns to the position where it abuts against the piston P, for example, when the inner periphery of the leaf valve L is squeezed in the middle of the piston rod R or the outer peripheral surface of the guide cylinder, the leaf valve L returns to the valve seat a. When the leaf valve L is formed by laminating a plurality of leaves to form a laminated leaf valve, each leaf is properly stacked. It has been kept securely there is no guarantee that the return to the original position together, in this respect, there is a possibility that the seating state of the valve seat a leaf valve L is not constant.

  As described above, in the conventional valve structure described above, the seated state of the leaf valve L on the valve seat a may not be constant, so that each time the shock absorber expands / contracts, the damping characteristic varies and the generated damping force may vary. There is sex.

  Therefore, the present invention was devised in order to improve the above-described problems, and the object of the present invention is to provide a valve structure capable of generating a stable damping force in a shock absorber and to be stable. A shock absorber capable of generating a damping force is provided.

  In order to solve the above-mentioned object, the valve structure of the shock absorber in the problem solving means of the present invention includes a valve disk in which a port is formed, a shaft member rising from the axial center of the valve disk, and a hole communicating with the port. A holding member that is attached to the shaft member so as to be movable in the axial direction and is stacked on the valve disc and holds an inner peripheral portion of an annular leaf valve that opens and closes the hole, and the holding member faces the piston. And energizing means for energizing.

  In order to solve the above-described object, a shock absorber in the problem solving means of the present invention includes a cylinder, a piston that is slidably inserted into the cylinder and that separates two pressure chambers in the cylinder, and a piston. A piston rod movably inserted into the cylinder, a port communicating with the two pressure chambers provided in the piston, and a cylindrical piston screwed to the tip of the piston rod to fix the piston to the piston rod A holding member that holds an inner peripheral portion of an annular leaf valve that has a hole that communicates with the port, is attached to the piston nut so as to be axially movable and is stacked on the piston, and opens and closes the hole; Biasing means for biasing the member toward the piston side.

  According to the valve structure of the present invention, the seating state of the leaf valve with respect to the holding member is constant, and it is the holding member that is directly seated on the valve disk, and the seating state is also constant because the movement in the axial direction is smooth. In the shock absorber to which this valve structure is applied, the damping characteristics are different every time it expands and contracts, so that the generated damping force does not vary, and a stable damping force can be generated.

  According to the shock absorber of the present invention, the seated state of the leaf valve with respect to the holding member is constant, and it is the holding member that is directly seated on the piston, and the seated state is also constant because it moves smoothly in the axial direction. It is possible to generate a stable damping force without causing a variation in the generated damping force due to different damping characteristics each time.

  The valve structure of the present invention will be described below with reference to the drawings. FIG. 1 is a longitudinal sectional view of a piston portion of a shock absorber in which a valve structure according to an embodiment is embodied.

  As shown in FIG. 1, the valve structure in one embodiment is embodied as an expansion-side damping valve of a piston portion of a shock absorber, and includes a piston 1 that is a valve disk in which a port 2 is formed, and a shaft of the piston 1. A cylindrical piston nut 6 as a shaft member rising from the center and a hole 25 communicating with the port 2 are mounted on the piston nut 6 so as to be freely movable in the axial direction, and are stacked on the piston 1 and the hole 25 is provided. A holding member 20 that holds the inner peripheral portion of the annular leaf valve 10 that opens and closes and a spring member 15 that is a biasing means that biases the holding member 20 in the direction of closing the port 2 are configured.

  On the other hand, a shock absorber in which the valve structure is embodied is well known and will not be described in detail, but specifically, for example, a cylinder 40 and a head member (not shown) that seals the upper end of the cylinder 40. ), A piston rod 5 slidably penetrating a head member (not shown), and a piston 1 fixed to the tip 5a of the piston rod 5 by a piston nut 6 screwed to the tip of the piston rod 5. An upper chamber 41 and a lower chamber 42 that are two pressure chambers separated by the piston 1 in the cylinder 40, a sealing member (not shown) that seals the lower end of the cylinder 40, and a piston rod that protrudes and retracts from the cylinder 40 The cylinder 40 is configured to include a reservoir or an air chamber (not shown) that compensates for a change in the cylinder volume corresponding to 5 volumes, and the cylinder 40 is filled with a fluid, specifically, hydraulic oil.

  In the valve structure, when the piston 1 moves upward in FIG. 1 with respect to the cylinder 40, the pressure in the upper chamber 41 rises and the port 2 is connected from the upper chamber 41 to the lower chamber 42. When the hydraulic oil moves through the leaf valve 10, the leaf valve 10 provides resistance to the hydraulic oil to cause a predetermined pressure loss, thereby generating a predetermined damping force in the shock absorber. Function as.

  Hereinafter, the valve structure will be described in detail. The piston 1 serving as a valve disk is formed in a bottomed cylindrical shape, and has the same circumference as the insertion hole 1b into which the piston rod 5 of the shock absorber is inserted into the shaft center portion of the bottom 1a. A plurality of ports 2 provided above, an annular window 3 communicating with each port 2, a valve seat 1c formed on the outer peripheral side of the window 3 serving as an outlet end of the port 2, and an outer periphery of the bottom portion 1a The outer cylinder portion 1d is provided. The piston 1 has a plurality of compression-side ports 1e that allow the flow of hydraulic oil from the lower chamber 42 to the upper chamber 41 when the shock absorber contracts, on the same circumference, and extend the bottom 1a. It is provided on the outer peripheral side from the side port 2.

  As described above, the piston rod 5 is inserted into the insertion hole 1b of the piston 1, and the tip 5a of the piston rod 5 is protruded downward in FIG. The outer diameter of the tip 5a of the piston rod 5 is set to be smaller than the outer diameter on the upper side in FIG. 1 from the tip 5a, and a step portion 5b is formed at a portion where the outer diameters of the upper side and the tip are different. Yes.

  The tip of the piston rod 5 is inserted into the insertion hole 1b of the piston 1 together with a pressure side leaf valve 30, a valve stopper 31 and the like formed by laminating a plurality of leaves. The cylindrical piston nut 6 is screwed into a screw portion 5c provided at the tip 5a of the piston rod 5, whereby the piston 1 is sandwiched between the step portion 5b of the piston rod 5 and the upper end of the piston nut 6. 5 is fixed.

  The piston nut 6 is formed in a cylindrical shape, and has a flange portion 6a at the tip which is the lower end in FIG. 1, and is screwed onto the tip 5a of the piston rod 5 as described above. The shaft member rises from the shaft center portion.

  As described above, by making the piston 1 have a bottomed cylindrical shape, the length from the upper end of the piston 1 (not shown) to the lower end of the piston nut 6 can be reduced, and the piston portion can be downsized. However, the shape of the piston 1 is not limited to this.

  In addition, a holding member 20 slidably contacting the outer periphery of the piston nut 6 is laminated on the bottom portion 1 a of the piston 1. The holding member 20 is specifically formed from an annular plate portion 21 and an inner peripheral portion of the plate portion 21. 1 is provided, and is mounted on the outer peripheral side of the piston nut 6 so as to be axially movable in the vertical direction in FIG.

  The holding member 20 has an outer diameter larger than that of the valve seat 1c provided on the piston 1 and a diameter that does not block the port 1e. Further, the plate portion 21 penetrates the upper and lower sides thereof. A plurality of holes 25 are provided on the same circumference.

  Further, in this holding member 20, a leaf valve 10 constituted by laminating a plurality of annular leaves, a spacer 7 serving as a fulcrum for bending the leaf valve 10 downward in FIG. While inserting the said cylinder part 22 in the stopper 8, the front-end | tip of the cylinder part 22 is crimped to the outer peripheral side, the control part 23 is formed, and the inner peripheral part of the leaf valve 10 is formed with this control part 23 and the board part 21. keeping.

  As described above, the leaf valve 10 has a so-called outward opening in which the inner peripheral side is sandwiched between the plate portion 21 and the holding portion 23, the inner peripheral portion is a fixed end, and the outer peripheral side is a free end. Further, an annular seat portion 21a disposed on the outer peripheral side of the hole 25 protrudes from the lower end of the plate portion 21 in FIG. 1, and the outer peripheral portion of the leaf valve 10 is seated on the seat portion 21a. That is, the leaf valve 10 closes the hole 25 when seated on the seat portion 21a, and opens the hole 25 when the outer peripheral side is bent and separated from the seat portion 21a.

  In addition, by projecting the seat portion 21a from the lower surface of the plate portion 21, an axial difference is provided between the support positions of the outer peripheral portion and the inner peripheral portion of the leaf valve 10, and the outer peripheral side of the leaf valve 10 is downward in FIG. By bending, the leaf valve 10 is given initial deflection, and by adjusting the initial deflection of the leaf valve 10, the pressure when the leaf valve 10 is separated from the seat portion 21a, that is, the valve opening pressure is adjusted. Can be done. The adjustment of the initial deflection described above is performed by, for example, inserting a spacer having a smaller diameter than the leaf valve 10 that does not block the hole 25 between the leaf valve 10 and the plate portion 21. This can be done by adjusting the difference in the axial direction to the support position of the portion and the inner peripheral portion.

  Further, in the holding member 20 of the present embodiment, the tip end of the cylindrical portion 22 is crimped to the outer peripheral side to form the holding portion 23 to hold the leak valve 10. 23, a screw portion is provided at the lower end that is the tip of the cylindrical portion 22, and an annular holding portion separate from the cylindrical portion 22 is screwed to the screw portion so that the leaf valve 10 and the separate portion The valve stopper 8 and the plate portion 21 may be sandwiched and held, or the valve stopper 8 may be used as the suppression portion if the valve stopper 8 is welded to the cylindrical portion 22.

  The spacer 7 serves as a fulcrum for the bending of the leaf valve 10, but an annular protrusion having the same shape as the spacer 7 is provided at the upper end of the valve stopper 8 in FIG. 1, and the protrusion 7 functions as the spacer 7. In the case where it is used, the spacer 7 can be omitted.

  Further, the axial length of the holding member 20 in the vertical direction in FIG. 1 is inclined with respect to the axis of the piston nut 6 in the vertical direction in FIG. The length is set so as not to be caught, and smooth movement of the holding member 20 in the axial direction with respect to the piston rod 5 and the piston nut 6 is ensured.

  In order to further prevent the above-mentioned galling, a chamfered portion or a chamfered portion that bends in a direction away from the piston nut 6 to the inner periphery of the lower end in FIG. 1 of the cylindrical portion 22 and the inner periphery of the upper end in FIG. May be provided.

  A spring member 15 as an urging means is interposed between the holding member 20 configured as described above and the flange 6a of the piston nut 6. The spring member 15 allows the holding member 20 to be attached to the piston 1. It is pressed and seated on the valve seat 1c side.

  That is, the urging force of the spring member 15 is applied to the holding member 20 to urge the holding member 20 in the direction of closing the port 2 with the spring member 15. Specifically, the upper end of the spring member 15 in FIG. 1 is supported by the lower end of the valve stopper 8 in FIG. 1, but the urging force of the spring member 15 acts on the holding member 20. Yes. Therefore, when the holding member 20 is urged, the urging force of the spring member 15 may finally act on the holding member 20, and thus the holding member 20 is indirectly applied to the holding member 20 via other members such as the valve stopper 8. An urging force may be applied.

  When the holding member 20 configured as described above is stacked on the bottom 1a of the piston 1 and seated on the valve seat 1c, the port 2 communicates with the lower chamber 42 through the hole 25. Furthermore, since the valve 2 is opened and closed by the leaf valve 10, the port 2 is opened and closed by the leaf valve 10 in such a state.

  On the other hand, when the holding member 20 moves against the piston 1 against the biasing force of the spring member 15 and moves downward in FIG. 1 from the state shown in FIG. When the piston 1 moves backward from the piston 1 and lifts, the holding member 20 is separated from the valve seat 1c to open the port 2.

  Next, the operation of the above-described valve structure will be described. As described above, when the piston 1 moves upward in FIG. 1 with respect to the cylinder 40, the pressure in the upper chamber 41 increases, and the operation in the upper chamber 41 increases. The oil tries to move through the port 2 and into the lower chamber 42.

  When the piston speed is in the low speed region, the holding member 20 is urged by the spring member 15 to be pressed so as to close the port 2, so that the piston 1 is kept seated on the valve seat 1 c. . Then, since the pressure in the upper chamber 41 does not form a gap between the valve seat 1c and the upper end of the plate portion 21 of the holding member 20 in FIG. 1, the hole 25 communicating with the port 2 is blocked. The leaf valve 10 acts on the leaf valve 10, and the outer peripheral side of the leaf valve 10 whose inner peripheral portion is held by the holding member 20 bends with the contact portion of the leaf valve 10 contacting the outer peripheral edge of the spacer 7 as a fulcrum. The hydraulic oil passes away through the gap between the leaf valve 10 and the seat portion 21a.

  On the other hand, the speed of the piston 1 is high, the difference between the pressure in the upper chamber 41 and the pressure in the lower chamber 42 is increased, and the force for pushing the holding member 20 downward in FIG. When the urging force is overcome, the entire holding member 20 is moved backward in the axial direction from the piston 1, that is, moved downward in FIG.

  At this time, it moves backward in the axial direction, that is, downward along with the holding member 20, but the leaf valve 10 is held by the holding member 20, and the holding member 20 is in sliding contact with the outer periphery of the piston nut 6. The inner circumferential side of each leaf having a very short axial length is not caught by the outer circumferential surface of the piston nut 6, and the holding member 20 is smoothly retracted from the piston 1.

  Therefore, when the holding member 20 is lifted from the piston 1 and retreats in the axial direction, the hydraulic oil passes through the annular gap formed between the valve seat 1c and the plate portion 21 of the holding member 20 and moves downward from the upper chamber 41. When the annular gap formed between the valve seat 1c and the plate part 21 of the holding member 20 is used as a flow path, the flow path area is as follows. The damping force generated by the shock absorber when the speed of the piston 1 is in the middle to high speed region is fixed to the inner periphery of the leaf valve. As a result, the valve structure can be kept low compared to the valve structure supported.

  When the piston speed decreases from that state and the difference between the pressure in the upper chamber 41 and the pressure in the lower chamber 42 decreases, the spring member 15 is now driven by the force that pushes the holding member 20 downward in FIG. However, since the holding member 20 is in sliding contact with the outer periphery of the guide cylinder 6, the axial direction of the leaf valve 10 is also increased. The inner periphery of each leaf having a very short length is not caught by the outer peripheral surface of the piston nut 6, and the holding member 20 can be smoothly moved in the direction of the piston 1.

  Further, since the holding member 20 holds the inner peripheral portion of the leaf valve 10, even if the holding member 20 repeatedly moves in the axial direction with respect to the piston nut 6 as the shaft member as described above, Since the inner peripheral portion does not move with respect to the holding member 20 and only the outer peripheral end side is separated from the seat portion 21a, each leaf of the leaf valve 10 can be separated from the holding member 20. Without being laminated, the seating portion 21a is only repeatedly detached and seated as a unit.

  Therefore, the seating state of the leaf valve 10 with respect to the seat portion 21a of the holding member 20 is constant, and it is the holding member 20 that is directly seated on the piston 1, and the seating state is also constant because the movement in the axial direction is smooth. In the shock absorber to which the valve structure is applied, the damping characteristic is different every time it expands and contracts, and the generated damping force does not vary, and a stable damping force can be generated.

  Further, according to the above description, in the valve structure according to this embodiment, the holding member 20 that holds the inner peripheral portion of the leaf valve 10 is in sliding contact with the outer periphery of the piston nut 6 that is a shaft member. Since the structure which advances and retreats with respect to 1 is adopted, the holding member 20 moves smoothly as compared with the conventional valve structure in which the leaf valve directly contacts the piston nut.

  Therefore, it is possible to prevent a situation in which the inner periphery of each leaf of the leaf valve 10 interferes with the outer periphery of the piston nut 6 as a shaft member and becomes a resistance to movement in the axial direction. The opening / closing operation of the port 2 by the holding member 20 corresponding to the opening / closing operation of the port 2 by lift and return becomes smoother than the conventional valve structure, and the response of the damping force generation of the shock absorber can be improved. .

  In particular, in the aspect where the moving direction of the piston 1 is reversed, that is, in the case of this embodiment, the shock absorber is switched from the expansion stroke to the compression stroke, the port 2 is quickly connected to the holding member 20 and the leaf. Since it is possible to close with the valve 10, it is possible to reduce the time for the hydraulic oil to freely pass from the lower chamber 42 to the upper chamber 41 via the port 2. Sufficient damping force can be generated.

  Further, since the holding member 20 holds the inner peripheral portion of the leaf valve 10 and the outer end of the leaf valve 10 only bends, the outer peripheral surface of the piston nut 6 as a shaft member is squeezed by the inner periphery of the leaf valve 10. There is no danger of contamination.

  In the above description, the shaft member is the piston nut 6. However, when the piston 1 can be directly fixed to the piston rod 5, the shaft member may be constituted by the tip of the piston rod 5. Further, the shaft member may be integrally formed on the shaft center portion of the piston 1.

  Further, in the above description, the urging means is the spring member 15 which is a coil spring in the figure, but a predetermined urging force may be applied to the holding member 20, and this may be applied to, for example, a disc spring or a leaf spring. Or an elastic body such as rubber.

  This is the end of the description of the embodiment of the valve structure, but the valve structure of the present invention can be embodied in the compression side damping valve of the piston portion of the shock absorber, or in the base valve portion. Of course, the present invention can be applied to a damping valve that functions as a damping force generating element that generates a damping force.

 It should be noted that the scope of the present invention is not limited to the details shown or described.

It is a longitudinal cross-sectional view in the piston part of the shock absorber in which the valve structure in one embodiment was embodied. It is a longitudinal cross-sectional view of the conventional valve structure.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Piston 1a which is a valve disc Bottom part 1b Insertion hole 1c Valve seat 1d Outer cylinder part 1e Pressure side port 2 Port 3 Window 5 Piston rod 5a Piston rod tip 5b Step part 5c Screw part 6 Piston nut 6a collar part 7 Spacer 8 Valve Stopper 10 Leaf valve 15 Spring member 20 as an urging means Holding member 21 Plate portion 21a Sheet portion 22 Tube portion 23 Holding portion 25 Hole 40 Cylinder 41 Upper chamber 42 Lower chamber

Claims (3)

A valve disk in which a port is formed, a shaft member that rises from the axial center of the valve disk, a hole that communicates with the port, is mounted on the shaft member so as to be axially movable, and is laminated on the valve disk and A shock absorber valve structure comprising: a holding member that holds an inner peripheral portion of an annular leaf valve that opens and closes a hole; and a biasing means that biases the holding member toward the piston. The valve disc has an annular valve seat disposed on the outer peripheral side from the port, and the holding member has an annular plate portion that has a hole communicating with the port and is seated on the valve seat, and a leaf that rises from the inner peripheral portion of the plate portion. The valve structure of the shock absorber according to claim 1, further comprising a cylinder portion inserted into the valve, wherein the inner peripheral portion of the leaf valve is held by a holding portion and a plate portion provided at a tip of the cylinder portion. A cylinder, a piston slidably inserted into the cylinder and separating two pressure chambers in the cylinder, a piston rod movably inserted into the cylinder via the piston, and the 2 provided in the piston A port that connects two pressure chambers, a cylindrical piston nut that is screwed to the tip of the piston rod and fixes the piston to the piston rod, and a hole that communicates with the port. A shock absorber provided with a holding member that holds the inner peripheral portion of the annular leaf valve that is stacked on the piston and opens and closes the hole, and a biasing means that biases the holding member toward the piston.

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