JP5080507B2 - Shock absorber - Google Patents

Description

The present invention relates to an improvement of a shock absorber.

  Conventionally, particularly in a shock absorber capable of adjusting damping force, for example, a cylinder, a piston rod movably inserted into the cylinder, and a piston rod slidably inserted into the cylinder A piston having a main damping passage that divides the inside of the cylinder into an upper chamber and a lower chamber and communicates the upper chamber and the lower chamber, and bypasses the upper damping chamber and the lower chamber by bypassing the main damping passage. And a bypass passage that communicates, and a rotary valve provided in the middle of the bypass passage changes the flow passage area in the bypass passage to adjust the damping force.

  As a structure for enabling the damping force adjustment, in detail, a hollow hole that opens from the tip of the piston rod to the lower chamber and leads to the lower chamber and an outer periphery of the piston rod that is mounted on the upper chamber side from the piston A chamber formed by the valve disk and a cap fitted to the lower side of the valve disk, a first passage communicating the chamber formed in the valve disk to the upper chamber, and opening from the outer periphery of the piston to avoid the main damping passage A second passage communicating with the inner periphery of the piston, a first port provided in the piston rod for communicating the hollow hole and the chamber, and a second port provided for the piston rod for communicating the hollow hole and the second passage. The rotary valve is accommodated in the hollow hole of the piston rod so as to be rotatable in the circumferential direction. The rotary valve is formed in a cylindrical shape and can be opposed to the first port. And the orifice hole, and a opposable second orifice hole to the second port (e.g., see Patent Document 1).

  In this shock absorber, the rotary valve is rotated with respect to the piston rod to change the degree of overlap (wrap) between the port and the orifice hole, thereby changing the flow passage area, so that the hydraulic oil can be rotated. It is possible to change the pressure loss when passing through the valve, thereby adjusting the damping force generated by the shock absorber.

JP 2008-39065 A (FIG. 1)

  As described above, the above-described rotary valve is accommodated in the piston rod, and in order to adjust the damping characteristic (characteristic of the generated damping force with respect to the piston speed) of the buffer over a wide range from soft to hard. In addition to the pair of first orifice holes, a pair of second orifice holes are juxtaposed in the bypass passage. The first orifice hole is formed by a valve disk and a cap mounted on the piston rod above the piston. For the convenience of allowing the second orifice hole to communicate with the second passage provided in the piston, the length of the second orifice hole is inevitably long.

  In addition, it is troublesome to provide the piston with the second passage leading from the side surface of the upper chamber of the piston to the inner periphery of the piston. Therefore, the piston in the prior art is formed by combining three pieces divided into three parts. A structure that simplifies the formation of the piston is used, and even if the second passage is post-processed or formed with a divided piece, the conventional shock absorber does not have this second passage. The piston cannot be used.

  Thus, in the shock absorber that realizes the damping force adjustment using the rotary valve, a special piston and a long rotary valve are necessary, and the manufacturing cost increases.

  In order to solve this, for example, a cylindrical spacer that forms a second passage is interposed between the cap and the piston, and a second port to be provided on the piston rod is provided at a position facing the spacer. do it. However, when using a spacer in this way, the positional relationship in the vertical direction is such that the cap is sandwiched between the first port and the second port, and between the inner periphery of the cap and the outer periphery of the piston rod. There is a problem that not only the second port but also the first port communicates with the second passage through the generated fitting gap.

  Since the first port does not allow hydraulic oil to pass through unless the leaf valve stacked on the valve disc is opened, the second passage and the first port communicate with each other through the fitting gap as described above. If this happens, even if you do not want the hydraulic oil to pass through the first port, it will pass through it, so there is a risk that this will not be possible even if you want to increase the damping characteristics and adjust to hardware. There is also a problem that the damping force varies greatly due to variations in the fitting gap.

  Therefore, the present invention was created to improve the above-described problems, and the object of the present invention is to shorten the rotary valve to reduce the manufacturing cost and to adjust a wide range of damping characteristics. Is to provide a shock absorber.

  In order to solve the above-described object, the problem solving means in the present invention includes a cylinder, a piston rod that is slidably inserted into the cylinder, and is slidably inserted into the cylinder and attached to the outer periphery of the piston rod. A piston having a main damping passage that divides the inside of the cylinder into an upper chamber and a lower chamber and communicates the upper chamber and the lower chamber; and a bypass passage that bypasses the main damping passage and communicates the upper chamber and the lower chamber. A hollow hole that opens from the tip of the piston rod and leads to the lower chamber, and a valve disc that is mounted on the outer periphery of the piston rod and on the upper chamber side from the piston, and is fitted to the lower side of the valve disc. A chamber formed by the cap, a first passage communicating the chamber formed by the valve disk to the upper chamber, and a space interposed between the cap and the piston. A second port provided in the piston rod to communicate the hollow hole and the chamber, and a second port provided in the piston rod to communicate the hollow hole and the second passage. In addition, in a shock absorber that accommodates a rotary valve that can be rotated in a circumferential direction in a hollow hole and that opens and closes a first port and a second port, In this case, a seal member, which is compressed in the axial direction and whose inner diameter is reduced and is in close contact with the outer periphery of the piston rod, is laminated on the cap in a compressed state.

  According to the shock absorber of the present invention, the rotary valve can be shortened in the axial direction, and the use of a special piston cannot be forced. Therefore, the manufacturing cost is reduced, which is economically advantageous.

  Further, the fitting gap between the cap and the piston rod is a dish-shaped ring or an annular ring having a cross-sectional shape, and when compressed in the axial direction, the inner diameter is reduced and the seal member is in close contact with the outer periphery of the piston rod. Since it is sealed, communication between the first port and the second passage is prevented, and it is possible to adjust a wide range of damping characteristics while enjoying the advantage of shortening the rotary valve and reducing the manufacturing cost.

  Furthermore, since the seal member is formed into an annular flat plate shape when compressed, the seal member is arranged in the axial direction even when compared with a seal member such as an O-ring or U-packing that seals between the cap and the piston rod. There is no space, and the length of the rotary valve can be set shorter.

It is a partial expanded longitudinal cross-sectional view of the shock absorber in one embodiment of the present invention. It is a side view of the rotary valve of the shock absorber in one embodiment of the present invention. It is a perspective view of the seal member in the shock absorber of one embodiment of the present invention. It is a perspective view which shows the modification of the sealing member in the buffer of one embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. As shown in FIG. 1, the shock absorber D of the present invention includes a cylinder 1, a piston rod 2 that is slidably inserted into the cylinder 1, and an outer periphery of the piston rod 2 that is slidably inserted into the cylinder 1. The piston 3 having main damping passages 3a and 3b that divide the inside of the cylinder 1 into an upper chamber R1 and a lower chamber R2 and communicate the upper chamber R1 and the lower chamber R2, and main damping passages 3a and 3b. The cylinder 1 includes a bypass passage 4 that bypasses and communicates the upper chamber R1 and the lower chamber R2 and a rotary valve 5 that is provided in the middle of the bypass passage 4 and changes the flow passage area of the bypass passage 4. A working fluid such as hydraulic oil is enclosed in the inside. In the shock absorber D, the damping force is adjusted by changing the flow passage area in the bypass passage 4 by the rotary valve 5 described above.

  Although not shown, the upper and lower ends of the cylinder 1 in FIG. 1 are sealed with a sealing member (not shown), and the cylinder 1 is held in a sealed state. When the working fluid is a liquid, when the shock absorber D expands or contracts, the piston rod 2 enters or leaves the cylinder 1 to compensate for the amount of liquid that becomes excessive or insufficient in the cylinder 1. Therefore, although not shown, it is natural that a gas chamber defined by a free piston inserted below the cylinder 1 or a reservoir communicating with the cylinder 1 is provided.

  Hereinafter, each member will be described in detail. The cylinder 1 is formed in a cylindrical shape, and a rod guide (not shown) for slidably supporting the piston rod 2 is provided at the upper end in FIG. .

  The piston rod 2 includes a hollow hole 2a that opens from the lower end in FIG. 1 and faces the lower chamber R2, and a control rod insertion hole 2b that continues to the hollow hole 2a and communicates with an upper end (not shown). 1, a spacer 6, a cap 10, and a valve disk 9 are mounted on the piston 3 and the upper chamber R <b> 1 side that is above the piston 3 in FIG. 1.

  A cylindrical rotary valve 5 is rotatably accommodated in the hollow hole 2a of the piston rod 2, and the lower side of the piston rod 2 is set to a small diameter to form a small diameter portion 2c and a step portion 2d. In addition, the small-diameter portion 2c is arranged so that the hollow hole 2a communicates with the outside of the piston rod so as to face each other, that is, two first pairs of upper and lower sides arranged at an interval of 180 degrees in the circumferential direction. Ports 2e and 2f and a pair of second ports 2g that communicate with each other through the hollow hole 2a to the outside of the piston rod are opened. In this embodiment, the first ports 2e and 2f described above are circular, and the second port 2g is a long hole along the longitudinal direction of the piston rod 2, but the shape is not limited thereto.

  The piston 3 is formed in an annular shape, and when the shock absorber D extends through the upper chamber R1 and the lower chamber R2, the working fluid passes and the main damping passage 3a on the expansion side, the upper chamber R1 and the lower chamber R2 are passed. And a pressure-side main damping passage 3b through which the working fluid passes when the shock absorber D is compressed. The leaf valves V1 and V2 are stacked on the upper and lower sides of the piston 3, respectively, and the lower end serving as the outlet end of the main damping passage 3a is opened and closed by the leaf valve V1, and conversely, the outlet end of the main damping passage 3b. The upper end is opened and closed by a leaf valve V2.

  Therefore, when the shock absorber D is extended, the leaf valve V1 applies a resistance to the flow of the working fluid that passes through the main damping passage 3a on the expansion side and moves from the upper chamber R1 to the lower chamber R2, thereby shock absorber. The other leaf valve V2 generates an extension-side damping force in D, and when the shock absorber D is compressed, the working fluid moves from the lower chamber R2 to the upper chamber R1 through the compression-side main damping passage 3b. A resistance is applied to the flow of the pressure to generate a compression side damping force in the shock absorber D.

  The spacer 6 is formed in a bottomed cylindrical shape, and a hole 6a that allows insertion of the small-diameter portion 2c of the piston rod 2 is provided at the bottom, and a notch 6c that communicates inside and outside is provided in the cylindrical portion 6b. The rod 2 is assembled on the outer periphery of the small diameter portion 2c. In addition, the notch 6c may be provided in the edge part of the cylinder part 6b, and may be provided in the middle of the cylinder part 6b in the shape of a hole. In this embodiment, the spacer 6 is directly stacked on the leaf valve V2 stacked above the piston 3, and functions as a valve stopper that regulates the amount of deflection of the leaf valve V2. Also good.

  Further, in the upper part of the spacer 6 in FIG. 1, an annular valve disk 9 assembled to the outer periphery of the small diameter portion 2 c of the piston rod 2 and an outer periphery of the piston rod 2 and fitted to the outer periphery of the valve disk 9. A bottomed cylindrical cap 10 is provided, and the valve disk 9 and the cap 10 partition the room 11 in the upper chamber R1.

  Specifically, the valve disk 9 includes an extension side passage 9a that penetrates the valve disk 9 and a pressure side passage 9b. The outlet end of the extension side passage 9a is opened and closed by a leaf valve V3 stacked below the valve disk 9 in FIG. 1, and the extension side passage 9a is a one-way passage that is opened only during the extension stroke of the shock absorber D. The resistance is set by the leaf valve V3 to the set working fluid. On the other hand, the outlet end of the pressure side passage 9b is opened and closed by a leaf valve V4 stacked above the valve disc 9 in FIG. 1, and the pressure side passage 9b is set as a one-way passage that is opened only during the compression stroke of the shock absorber D. The leaf valve V4 provides resistance to the working fluid passing therethrough. Since the bending rigidity of the leaf valves V3 and V4 is set to be smaller than the bending rigidity of the leaf valves V1 and V2 stacked on the piston 3, the valve opening pressure is lower than the valve opening pressure of the leaf valves V1 and V2. The expansion side passage 9a and the pressure side passage 9b are opened by the pressure.

  The cap 10 is formed in a bottomed cylindrical shape, and a hole 10a that allows the small-diameter portion 2c of the piston rod 2 to be inserted is provided at the bottom, and the opening of the cylindrical portion is fitted to the outer periphery of the valve disc 9. Are combined. And between the bottom part of this cap 10 and the valve disc 9, the valve | bulb restraint 12 which is a bottomed cylinder shape and is set to a diameter smaller than the cap 10 is interposed, The said valve | bulb restraint 12 is the bottom part. The leaf valve V3 is set to open outward by preventing the leaf valve V3 from lifting from the inner periphery of the valve disc 9. Further, the valve restraint 12 includes a notch 12b in the cylindrical portion 12a, and the inside and the outside communicate with each other by the notch 12b. In addition, the notch 12b may be provided in the edge part of the cylinder part 12a, and may be provided in the middle of the cylinder part 12a in the shape of a hole.

  Further, a seal member 7 is interposed between the cap 10 and the upper end of the spacer 6, and the fitting gap between the cap 10 and the piston rod 2 is sealed by the seal member 7. Specifically, as shown in FIGS. 1 and 3, the seal member 7 has a frustum side shape, and when compressed in the axial direction, the seal member 7 is deformed from a dish-like shape to a flat annular shape. However, the inner diameter is reduced and the outer diameter is increased. Note that the seal member 7 may have a dish-like shape formed by rotating an arc, and even if the cross-section is an arc, the inner diameter is reduced and the outer diameter is increased when crushed as described above. Diameter.

  When the seal member 7 is interposed between the cap 10 and the spacer 6 as described above, the seal member 7 is compressed in the axial direction, the inner diameter is reduced, and the inner circumference is in close contact with the outer circumference of the piston rod 2. Thus, the flow of the hydraulic oil is blocked through the inside of the seal member 7.

  Further, the seal member 7 is sandwiched between the cap 10 and the spacer 6, and the upper surface in FIG. 1 is in close contact with the lower end of the cap 10, so that the fitting gap between the cap 10 and the piston rod 2 is sealed. become.

  Thus, since the inner diameter of the seal member 7 is reduced when the seal member 7 is compressed in the axial direction, the seal member 7 is compressed in the axial direction to be flat when it is attached. In addition, when the seal member 7 is attached to the piston rod 2, the inner diameter of the seal member 7 is set to the piston due to the characteristic of the seal member 7 that the inner periphery is in close contact with the outer periphery of the piston rod 2 when the seal member 7 is compressed. Since the seal member 7 may be attached to the piston rod 2 in a non-compressed state that is larger than the outer diameter of the rod 2, the attachment to the piston rod 2 can be performed smoothly.

  The seal member 7 may be laminated on the upper surface of the cap 10 in FIG. 1, and in this case, the seal member 7 may be sandwiched between the cap 10 and the valve restraint 12 to be in a compressed state.

  Further, as shown in FIG. 4, the seal member 7 can be an annular shape having a cross-sectional mountain shape, and even if the seal member 7 is set to have a cross-sectional mountain shape, When the load is applied and compressed, the inner diameter is reduced, so that the outer periphery of the piston rod 2 can be sealed at the inner periphery as in the seal member 7 shown in FIGS. The mounting property to the piston rod 2 is also good. In addition, in the place shown in FIG. 4, although the cross section of the sealing member 7 is made into the triangular shape where the top part was sharp, it is good also as circular arc shape.

  Further, the small diameter portion 2c of the piston rod 2 includes, in order from the top in FIG. 1, a valve stopper 13, a leaf valve V4, a valve that is restricted from moving upward with respect to the piston rod 2 by the step portion 2d of the piston rod 2. A disc 9, a leaf valve V3, a valve restraint 12, a cap 10, a seal member 7, a spacer 6, a leaf valve V2, a piston 3, a leaf valve V1, and an annular valve stopper 14 that regulates the amount of deflection of the leaf valve V1 are assembled. Each member described above is fixed to the piston rod 2 by a piston nut 15 screwed to the lowermost end of the piston rod 2.

  Thus, in a state where each member is assembled and fixed to the piston rod 2, the second port 2 g provided on the piston rod 2 faces the cylindrical portion 6 b of the spacer 6, and further, the cylindrical portion 12 a of the valve retainer 12. The first ports 2e and 2f provided on the piston rod 2 are opposed to each other, and the hollow hole 2a facing the lower chamber R2 is connected to the upper chamber R1 via the second port 2g and the notch 6c provided in the spacer 6. Are connected to the hard side ports 2e and 2f, the notch 12b provided in the valve retainer 12, the chamber 11 partitioned by the valve disc 9 and the cap 10, and the extension side passage 9a and the pressure side passage 9b provided in the valve disc 9. Via the upper chamber R1.

  Therefore, in this embodiment, the bypass passage 4 includes the hollow hole 2a that opens from the tip of the piston rod 2 and communicates with the lower chamber R2, the second port 2g, the notch 6c provided in the spacer 6, the first port 2e, 2f, a notch 12b provided in the valve retainer 12, a chamber 11, an extension side passage 9a and a pressure side passage 9b. In this embodiment, the first passage is an extension side passage 9a provided in the valve disc 9. The second passage is formed by a notch 6 c provided in the spacer 6.

  Note that the extension side passage 9a and the pressure side passage 9b functioning as the first passage are set to be one-way, and are opened and closed by the leaf valves V3 and V4, so that the valve opening pressure of the leaf valves V3 and V4 is reached. Up to this point, the corresponding extension side passage 9a and pressure side passage 9b are closed, and the bypass passage 4 communicates the upper chamber R1 and the lower chamber R2 through the hollow hole 2a, the second port 2g and the notch 6c provided in the spacer 6. It is like that.

  Subsequently, the rotary valve 5 accommodated in the hollow hole 2a of the piston rod 2 has its outer peripheral surface in sliding contact with the inner peripheral surface of the hollow hole 2a, and is rotatable in the circumferential direction. The rod 2 is connected to the control rod 16 inserted into the control rod insertion hole 2b.

  The control rod 16 is connected to an output shaft of a stepping motor (not shown) fixed to the upper end of the piston rod 2, and the rotary valve 5 is moved in the circumferential direction with respect to the piston rod 2 by driving the stepping motor. Step rotation can be performed for each predetermined rotation angle.

  Further, a cylindrical stopper 18 is press-fitted in the hollow hole 2a of the piston rod 2 below the rotary valve 5 in FIG. 1, and this stopper 18 prevents the rotary valve 5 from falling off the piston rod 2. doing. In addition, a cylindrical resin bearing 17 is interposed between the stopper 18 and the rotary valve 5 to ensure smooth rotation of the rotary valve 5.

  The rotary valve 5 includes two pairs of upper and lower first orifice holes 19 and 20 that communicate with the inside and outside of the side and face the first ports 2e and 2f formed in the small diameter portion 2c of the piston rod 2, and a second port. And a pair of second orifice holes 21 that can face 2g.

  As shown in FIG. 2, the orifice holes 19 and 20 are both provided with circular holes 19a and 20a and slits 19b and 20b communicating with the circular holes 19a and 20a, respectively, along the circumferential direction. The slits 19b and 20b themselves also pass through the thickness of the valve body 8 and communicate with the inside and outside of the valve body 8. Further, as shown in FIG. 2, the second orifice hole 21 has a long hole 21a along the axis of the valve body 8 and the same shape as the second port 2g, and a groove 21b communicated with the long hole 21a along the circumferential direction. The long hole 21 a communicates with the inside and outside of the valve body 8, but the groove 21 b itself does not penetrate the thickness of the valve body 8 and only communicates with the long hole 21 a and does not communicate with the inside and outside of the valve body 8. It is like that.

  Then, by making the second orifice hole 21 face the second port 2g, the notch 6c as the second passage and the inside of the rotary valve 5 are communicated, and the notch 6c, the rotary valve 5 and the hollow hole 2a of the piston rod 2 are communicated. The upper chamber R1 and the lower chamber R2 are in communication with each other, and the second orifice hole 21 is not opposed to the second port 2g, and the side surface of the rotary valve 5 is opposed to the second port 2g. Is closed, the communication between the upper chamber R1 and the lower chamber R2 is blocked, and the degree of overlap between the second port 2g and the second orifice hole 21 is changed to change the second port 2g and the second chamber R2. The channel area in the channel formed by the two orifice holes 21 can be changed. In addition, when only the groove 21b is made to oppose the port 2g without making the long hole 21a oppose the port 2g, the flow area can be made extremely small and the change ratio of the flow area to the rotation of the rotary valve 5 can be made small. However, whether or not to install the groove 21b is arbitrary and can be abolished.

  Similarly, the first orifice holes 19 and 20 are made to face the corresponding first ports 2e and 2f, respectively, so that the chamber 11 and the rotary valve 5 communicate with each other, and the leaf valve V3 stacked on the valve disk 9 is stacked. If one of the V4 is opened, the upper chamber R1 and the lower chamber R2 are in communication with each other, and the side surface of the rotary valve 5 is made to face the first port 2e without the first orifice holes 19 and 20 facing the first ports 2e and 2f. When the first ports 2e and 2f are closed so as to face 2f, the communication between the upper chamber R1 and the lower chamber R2 through the space 11 is blocked, and the first ports 2e and 2f By changing the overlapping degree of the first orifice holes 19 and 20, the flow area in the flow path formed by the first ports 2e and 2f and the first orifice holes 19 and 20 is changed. So that the can Rukoto.

  The first orifice holes 19 and 20 include not only circular holes 19a and 20a that are longer in the circumferential direction than the long hole 21a of the second orifice hole 21, but also slits 19b and 20b that are longer than the groove 21b. Therefore, the rotary valve 5 is made to face the first ports 2e, 2f with the slits 19b, 20b of the first orifice holes 19, 20 from the state in which the long hole 21a of the second orifice hole 21 faces the second port 2g. In this way, the second orifice hole 21 cannot face the second port 2g before the first orifice holes 19 and 20 cannot face the first ports 2e and 2f. 2 g is blocked. In a state where the second orifice hole 21 is directly opposed to the second port 2g, that is, in a state where the long hole 21a is completely opposed to the second port 2g, the circular holes 19a of the first orifice holes 19, 20 are provided. , 20a are directly opposed to the first ports 2e, 2f, the flow passage area of the bypass passage 4 is maximized, and the rotary valve 5 is opposed to the slits 19b, 20b of the first orifice holes 19, 20 to the first ports 2e, 2f. When the rotation is performed in the circumferential direction, the flow passage area in the bypass passage 4 is gradually reduced. Finally, not only the second port 2g but also the first ports 2e and 2f are side surfaces of the valve body 8. As a result, the bypass area 4 is closed because the flow area is zero. In this way, by rotating the rotary valve 5 with respect to the piston rod 2, the flow passage area in the bypass passage 4 can be changed.

  When the second orifice hole 21 and the second port 2g are in communication when the shock absorber D expands and contracts, the main fluid passes through the main damping passages 3a and 3b opened and closed by the leaf valves V1 and V2. Priority is given to the upper chamber R1 and the lower chamber R2 through the second orifice hole 21 and the second port 2g. At this time, the first orifice holes 19 and 20 are opposed to the first ports 2e and 2f, but when the expansion / contraction speed of the shock absorber D is in a low speed region, the pressure in the upper chamber R1 or the lower chamber R2 is changed to the leaf valve V3. , V4 does not reach the valve opening pressure, the expansion side passage 9a and the pressure side passage 9b remain closed, the expansion / contraction speed of the shock absorber D is in the high speed region, and the pressure in the upper chamber R1 or the lower chamber R2 is the leaf valve. Even if the valve opening pressure of V3 and V4 is reached and the expansion side passage 9a or the pressure side passage 9b is opened, the working fluid is preferentially connected to the second orifice hole 21 and the second orifice because the resistance in the leaf valves V3 and V4 is large. Passes through the port 2g and goes back and forth between the upper chamber R1 and the lower chamber R2.

  And when the 2nd orifice hole 21 and the 2nd port 2g are a communication state, since the flow-path area in the bypass path 4 is large and flow-path resistance becomes small, the damping coefficient in the buffer D (damping force with respect to expansion-contraction speed) The shock absorber D generates a soft damping force.

  On the other hand, when the rotary valve 5 is rotated from the above-described state to reduce the lap area between the second orifice hole 21 and the second port 2g, the working fluid becomes the second orifice hole 21 and the second port. The resistance at the time of passing through 2g becomes large and it becomes difficult to pass through this, and the bending rigidity in the leaf valves V3 and V4 is set to be smaller than the bending rigidity in the leaf valves V1 and V2. , V4 are pushed open to move back and forth between the upper chamber R1 and the lower chamber R2 through the first orifice holes 19 and 20. The damping force can be adjusted by changing the lap area between the first orifice holes 19 and 20 and the first ports 2e and 2f. Further, when the expansion / contraction speed of the shock absorber increases, the piston 2 is finally stacked. The leaf valves V1 and V2 thus opened are opened. Also in this case, since the working fluid in the upper chamber R1 and the lower chamber R2 exchanges with each other through the first orifice holes 19 and 20, the lap area between the first orifice holes 19 and 20 and the first ports 2e and 2f is reduced. The damping force can be adjusted by changing, and the smaller the wrap area between the first orifice holes 19 and 20 and the first ports 2e and 2f, the smaller the flow path area and the damping in the shock absorber D. As the coefficient increases, the flow resistance in the bypass 4 that bypasses the main damping passages 3a and 3b increases, and the shock absorber D generates a hard damping force.

  Now, in the shock absorber D configured as described above, the spacer 6 is interposed between the cap 10 and the piston 3, and the second passage is formed in the spacer 6. Compared to the conventional shock absorber, at least the thickness of the leaf valve V2 and the valve stopper can be shortened in the axial direction.

  Furthermore, since the second passage is formed in the spacer 6, it is not necessary to form the second passage in the piston 3, so that a general piston having no second passage can be used.

  As described above, according to the shock absorber D of the present invention, the rotary valve 5 can be shortened in the axial direction, and the use of a special piston cannot be forced. Therefore, the manufacturing cost is reduced, which is economically advantageous.

  Further, the fitting gap between the cap 10 and the piston rod 2 is a dish-shaped ring or an annular ring having a cross section, and when compressed in the axial direction, the inner diameter is reduced and the piston rod 2 is in close contact with the outer periphery. Since it is sealed by the seal member 7, the communication between the first ports 2e, 2f and the notch 6c as the second passage is prevented, and the rotary valve 5 can be shortened and the manufacturing cost can be reduced while being widely used. It is possible to adjust the attenuation characteristics.

  Further, since the seal member 7 becomes an annular flat plate shape when compressed, the seal member 7 can be compared with a seal member such as an O-ring or U-packing that seals between the cap 10 and the piston rod 2. Does not take a space in the axial direction, and the length of the rotary valve 5 can be set to be shortened accordingly.

  The number of the first orifice holes and the number of the first ports facing the first orifice holes and the shapes of the first orifice holes 19 and 20, the second orifice holes 21, the first ports 2e and 2f, and the second port 2g are arbitrary. , It can be set to a suitable shape according to the damping characteristic to be achieved by the shock absorber D.

 This is the end of the description of the embodiment of the shock absorber D, but the scope of the present invention is not limited to the details shown or described.

The present invention can be used, for example, in a shock absorber that suppresses vibration of a vibration control target such as a vehicle or a building.

DESCRIPTION OF SYMBOLS 1 Cylinder 2 Piston rod 2a Hollow hole 2b in piston rod Control rod insertion hole 2c in piston rod Small diameter part 2d in piston rod Step part 2e in piston rod, 2f First port 2g in piston rod Second port 3 in piston rod Piston 3a 3b Main damping passage 4 Bypass passage 5 Rotary valve 6 Spacer 6a Hole 6b in spacer 6b Spacer cylinder 6c Notch 7 as second passage 7 Seal member 9 Valve disk 9a Extension side passage 9b Pressure side passage 10 Cap 10a Hole 11 in cap 12 Valve restraint 12a Tube portion 12b for valve restraint Notches 13 and 14 for valve restraint Valve stopper 15 Piston nut 16 Control rod 17 Bearing 18 Stopper 19, 20 first orifice hole 19a, 20a circular hole 19b, 20b slit 21 second orifice hole 21a long hole 21b in orifice hole groove D in orifice hole buffer R1 upper chamber R2 lower chamber V1, V2, V3, V4 leaf valve

Claims (1)

A cylinder, a piston rod that is slidably inserted into the cylinder, and is slidably inserted into the cylinder and mounted on the outer periphery of the piston rod to divide the inside of the cylinder into an upper chamber and a lower chamber; A piston having a main damping passage that communicates with the chamber, and a bypass passage that bypasses the main damping passage and communicates the upper chamber and the lower chamber. The bypass passage opens from the tip of the piston rod to the lower chamber. A chamber formed by a hollow hole that communicates, a valve disk that is mounted on the outer chamber side of the piston rod on the upper chamber side from the piston, and a cap that fits on the lower side of the valve disk; and a chamber that is formed on the valve disk. A first passage communicating with the upper chamber, a second passage provided in a spacer interposed between the cap and the piston, a hollow hole provided in the piston rod and the chamber And a second port provided in the piston rod to communicate the hollow hole and the second passage, and is rotatable in the circumferential direction in the hollow hole. And a shock absorber containing a rotary valve that opens and closes the second port, which is a dish-shaped ring or a circular ring with a cross-section, and when compressed in the axial direction, the inner diameter is reduced and the piston rod A shock absorber characterized in that a seal member that is in close contact with the outer periphery is laminated on a cap in a compressed state.

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