JP4417823B2 - Shock absorber - Google Patents

Description

  The present invention relates to a shock absorber, and more particularly to an improvement of a shock absorber having a damping characteristic depending on piston displacement.

  In general, a shock absorber attenuates vibrations acting on vehicles, equipment, and structures. For example, if a high damping force is generated at the stroke end, the shock absorber and the piston at the time of maximum expansion or compression If the impact from the interference with the cylinder end can be mitigated, or if it is interposed between column beams as a vibration control device that suppresses vibration of the structure, a high damping force is applied at the center of the stroke. It may be advantageous to generate a low damping force at the stroke end for the purpose of dissipating the elastic energy accumulated in the columns and beams.

  As described above, depending on the application of the shock absorber, the shock absorber may be optimized for the application by having a damping characteristic depending on the piston displacement, and various kinds of such shock absorbers have been developed.

  This type of shock absorber has, for example, a cylinder, a piston slidably inserted in the cylinder, two pressure chambers partitioned by the piston in the cylinder, a rod connected to the piston, and hydraulic oil 2 A damping valve that provides resistance to the flow of hydraulic oil when alternating between the two pressure chambers, a pair of grooves provided along the axial direction on the inner periphery of both ends of the cylinder, and a piston provided in the piston with a predetermined amount with respect to the cylinder When it is displaced, that is, it is configured to include a bypass port that faces the groove in a predetermined stroke range, and when the predetermined stroke range is reached, the bypass port is opposed to the groove and a bypass path is formed. The pressure chamber is communicated via a bypass formed by the groove and the bypass port.

  Therefore, according to this shock absorber, in the vicinity of the piston neutral position, the hydraulic oil exchanges the two pressure chambers only through the damping valve and generates a high damping force, but the piston is displaced with respect to the cylinder. When approaching the stroke end, the hydraulic oil exchanges the two pressure chambers not only through the damping valve but also through the bypass, so that the shock absorber generates a low damping force ( For example, see Patent Document 1).

On the other hand, there is also a type in which a groove is formed in the spool that penetrates the piston to form a bypass passage. In this shock absorber, a low damping force is generated near the neutral position of the piston, and a high damping force is generated near the stroke end (for example, Patent Document 2).
JP 2003-322193 A (from page 6, left column, line 6 to line 46, FIGS. 1 and 3) JP 2004-11733 A (from page 6, line 6 to line 10, page 1)

  However, the above-described conventional shock absorber does not have a functional problem, but has the following disadvantages.

  In this type of shock absorber, the piston displacement, that is, the generated damping force is changed within a predetermined stroke range. Therefore, when the shock absorber is attached to the vehicle, equipment, or structure to be applied, the piston is just It is necessary to set the neutral position to be the mounting length (hereinafter referred to as “reference mounting length”) arranged at the center of the cylinder.

  In other words, if the mounting length of the shock absorber does not become the reference mounting length, the neutral position of the piston when the shock absorber is mounted will sway from side to side with respect to the cylinder, and the stroke range will sway from side to side. Become.

  Then, for example, even in a scene where the shock absorber must generate a low damping force, a bypass path cannot be formed due to the above-mentioned shaking, and a low damping force cannot be generated. It is possible for a bypass path to be formed.

  Therefore, in the conventional shock absorber, as described above, it is necessary to strictly manage the mounting length, but there may be a dimensional tolerance or the like in the mounting portion of the vehicle or the like, and the mounting length as set is realized. May be difficult, and there is a risk that the mounting operation to the mounting site becomes very complicated.

  In addition, there are ball joints that are equipped with ball joints at both ends of the shock absorber, and the distance between the ball joints can be finely adjusted by rotating the cylinder or rod with respect to the ball joint sphere. For shock absorbers used for seismic isolation applications, the shock absorber itself is large and the mounting space is small, so the above fine adjustment cannot be performed with the shock absorber attached to the attachment site. Temporarily fix to the attachment site, measure the installation length, then remove the shock absorber from the attachment site, perform the above fine adjustment, and reattach the shock absorber to the attachment site. Therefore, the mounting work of the shock absorber was very inconvenient.

  Accordingly, the present invention has been developed to improve the above-described adverse effects, and its object is to make the mounting work easy even in a position-dependent shock absorber.

In order to achieve the above object, a cylinder, a piston that is slidably inserted into the cylinder, two pressure chambers partitioned by the piston in the cylinder, and a rod connected to the piston are provided. In the shock absorber in which a bypass passage is formed to communicate two pressure chambers within the stroke range, the adjusting means for adjusting the predetermined stroke range is provided, and the adjusting means is communicated with the two pressure chambers. A housing having a hollow portion, a sleeve movably inserted into the hollow portion of the housing, a groove on the outer peripheral side portion and slidably inserted into the sleeve, and provided on the rod to the axis of the rod A spool whose tip is in contact with an inclined surface that is inclined with respect to the rod, and an urging means that urges the spool toward the rod, and within a predetermined stroke range, The is characterized in that is opposed to the opening of the passage communicating opening and the and the other pressure chamber sleeve passage communicating the inside and one pressure chamber sleeve.

  According to the present invention, it is possible to adjust the predetermined stroke range in which the damping force is changed by the adjusting means, and even if the mounting length of the shock absorber does not become the reference mounting length, that is, the piston neutral position is the shock absorber. Even when the mounting position is shifted from the center of the cylinder, the predetermined stroke range for changing the damping force can be set similarly to the case where the mounting length is the reference mounting length.

  Therefore, in the present invention, the mounting operation of the shock absorber can be made remarkably simple and easy as compared with the conventional shock absorber which must have a mounting length strictly equal to the reference mounting length. It can be done.

  In addition, since the above adjustment can be performed without requiring a large force, even when the shock absorber is large or when the mounting space is small, the adjustment work is performed with the shock absorber attached to the attachment site. Can be completed, and the position adjustment work becomes very easy.

  Furthermore, even in situations where the shock absorber must be kept in a compressed state when the shock absorber is installed, if the damping force is set low by the adjusting means, the compressed state can be maintained. Since it becomes very easy, the mounting work can be facilitated also in this respect.

  The present invention will be described below based on the illustrated embodiment. FIG. 1 is a cross-sectional view of the shock absorber according to the first embodiment. FIG. 2 is a partially enlarged longitudinal sectional view of the shock absorber according to the first embodiment. FIG. 3 is a diagram illustrating the damping characteristics of the shock absorber according to the first embodiment. FIG. 4 is a longitudinal sectional view of the shock absorber according to the second embodiment.

As shown in FIG. 1, the shock absorber D <b> 1 in the first embodiment includes a cylinder 1, a piston 2 slidably inserted into the cylinder 1, a rod 3 connected to the piston 2, and a cylinder 1. It is provided with two pressure chambers R1, R2 partitioned by a piston 2 and an adjusting means T, and is configured as a so-called double rod type shock absorber. In the drawing, this shock absorber D1 is a structure. It is embodied in the vibration damping device.
The adjusting means T includes a housing 10 having a hollow portion 12 communicated with two pressure chambers R1 and R2, a sleeve 25 movably inserted into the hollow portion 12 of the housing 10, and an outer peripheral side portion. And a spool 36 that is slidably inserted into the sleeve 25 and that has a tip abutting against an inclined surface that is provided on the rod 3 and that is inclined with respect to the axis of the rod 3; And an opening of the passage 14 that communicates the grooves 38 and 39 of the spool 36 with the inside of the sleeve 25 and one pressure chamber R1 and the sleeve 25 within a predetermined stroke range. It is made to oppose the opening of the channel | path 13 which connects an inside and the other pressure chamber R2.

  Hereinafter, in detail, the cylinder 1 is formed in a cylindrical shape, and the pressure chambers R1 and R2 partitioned by the piston 2 in the cylinder 1 are filled with a liquid such as hydraulic oil.

  Further, the piston 2 is provided with flow paths 4 and 5 communicating with the pressure chambers R1 and R2. Further, in the middle of the flow path 4, the liquid passes from the pressure chamber R2 to the pressure chamber R1. A damping valve 6 for blocking and allowing the flow of the liquid from the pressure chamber R1 to the pressure chamber R2 while blocking the passage of the liquid from the pressure chamber R1 to the pressure chamber R2 in the middle of the flow path 5 A damping valve 7 is provided for giving resistance to the flow of liquid while allowing passage from the chamber R2 to the pressure chamber R1.

  This damping valve 6 is a normally closed type damping valve urged in a closing direction by a spring (not shown), and the pressure on the upstream side of the flow path 4 is a pilot pressure, and the pilot pressure is a predetermined pressure. (Cracking pressure) or more, the thrust acting on the valve body (not shown) by this pilot pressure can overcome the spring force and open, and the cracking pressure when the damping valve 6 is opened is arbitrary. Set to

  Since the damping valve 7 has the same configuration as the damping valve 6, the description thereof will be omitted.

  Further, the housing 10 of the adjusting means T is provided at the left end of the cylinder 1 in FIG. 1, and the cylinder 8 is connected to the left end of the housing 10, and the ball joint B <b> 1 is connected to the left end of the cylinder 8. The cylinder 1 is attached to the attachment portion A1 which is a pillar or beam of the structure via the ball joint B1.

  The tube 8 is provided with a hole 9 that communicates the inside and the outside of the tube 8, and when the rod 3 advances and retreats to the tube 8, outside air flows into or out of the tube 8 through the hole 9. It is not hindered.

  On the other hand, a ball joint B2 similar to that connected to the cylinder 8 described above is provided at the right end of the rod 3 in FIG. 1, and the rod 3 is connected to the column of the structure through the ball joint B2. It attaches to attachment part A2 which is a beam.

  In turn, the adjusting means T includes a hollow housing 10, a sleeve 25 that is slidably inserted into the housing 10, a spool 36 that is slidably inserted into the sleeve 25, and a spring 41 that is a biasing means. It is configured with.

  Hereinafter, the adjustment means T will be described in detail. As shown in FIGS. 1 and 2, the housing 10 includes a guide hole 11 into which the rod 3 is slidably inserted, a hollow portion 12 orthogonal to the guide hole 11, A passage 13 communicating with the hollow portion 12 and the one pressure chamber R2, a passage 14 communicating with the hollow portion 12 and the other pressure chamber R1, and a communication path 15 communicating with the passage 13 and the passage 14. A communication passage 16 that communicates the passage 15 and the hollow portion 12, and a pair of check valves 17 and 18 that are provided in the middle of the communication passage 15 so as to face each other with the connection portion of the communication passage 16 as a boundary. Further, a screw groove 20 is provided in the vicinity of the opening of the hollow portion 12, that is, in the drawing.

  Further, at the left end of the rod 3 inserted into the guide hole 11, a tapered portion 19, which is an inclined surface inclined with respect to the axis, is formed in an annular shape along the circumference of the rod 3.

  The sleeve 25 inserted into the hollow portion 12 is formed in a bottomed cylindrical shape, and three pairs of annular grooves 26, 27, 28, 29, 30 formed at positions facing each other on the inner and outer peripheries thereof. , 31 are formed, and the paired annular grooves 26, 27, 28, 29, 30, 31 are communicated with each other through holes 32, 33, 34 penetrating through the bottoms thereof.

  Further, a screw thread 35 is provided on the outer periphery in the vicinity of the upper end of the sleeve 25. When the sleeve 25 is inserted into the hollow part 12 of the housing 10, the screw thread 35 is inserted into the screw groove 20 of the hollow part 12. Can be screwed together.

  In this state, the annular groove 26 of the sleeve 25 is set so as to face the passage 13 that communicates with the hollow portion 12, the annular groove 28 faces the communication passage 16, and the annular groove 30 faces the passage 14. Accordingly, the passages 13 and 14 and the communication passage 16 are communicated with each other in the sleeve 25.

  The annular grooves 26, 28, and 30 provided on the outer peripheral side of the sleeve 25 are provided so as to maintain a certain degree of communication even when the sleeve 25 is moved up and down with respect to the housing 10. It may be omitted, and an annular groove may be provided on the inner peripheral side of the hollow portion 12.

  The nut 25 is screwed onto the screw thread 35 from the outside of the housing 10 so that the sleeve 25 can be securely fixed to the housing 10.

  An annular groove (not shown) is formed on the inner peripheral side of the hollow portion 12 of the housing 10 and between the screw thread 35 and the annular groove 26 of the sleeve 25. An O-ring (not shown) is inserted to seal between the hollow portion 12 and the outer periphery of the sleeve 25 to prevent liquid leakage.

  Further, a spool 36 is slidably inserted into the sleeve 25, and the spool 36 includes a cylindrical main body 37, grooves 38 and 39 formed on the side of the main body 37, and the main body 37. The tip provided so as to protrude at the lower end in FIG. 1 is configured to include a spherical convex portion 40.

  Further, a spring 41 is interposed between the upper end of the spool 36 in the drawing and the bottom portion of the sleeve 25 which is the upper portion in the drawing, and the spool 36 is urged downward in the drawing by the spring 41. ing.

  The tip of the convex portion 40 of the spool 36 is in contact with the tapered portion 19 of the rod 3.

  Therefore, the spool 36 moves up and down along the taper portion 19 of the rod 3 when the rod 3 moves in the left-right direction in the figure with respect to the cylinder 1, that is, when the shock absorber operates.

  The urging means plays a role of bringing the spool 36 into contact with the tapered portion 19 of the rod 3 with respect to the left and right movement of the rod 3. As the urging means, an air spring is used in addition to the spring 41. Alternatively, other means may be used as long as it plays the above role.

  In addition, since the front-end | tip of the said convex part 40 is made into the spherical shape, when the rod 3 moves to the left-right direction in the figure with respect to the cylinder 1, the movement of the rod 3 is not prevented.

  In addition, the inclined surface may be formed by notching a part of the rod 3 or the like. However, since the inclined surface of the rod 3 is an annular tapered portion 19, when the rod 3 rotates in the circumferential direction, the spool There is an advantage that it is possible to prevent 36 from moving up and down as the rod 3 rotates.

  The vertical width in the figure, which is the axial width of the groove 38 of the spool 36, is set so as to face the annular groove 27 and the annular groove 29 of the sleeve 25 so that they can communicate with each other. The vertical width in the figure, which is the axial width, is set so as to oppose the annular groove 31 and the annular groove 29 of the sleeve 25 so that they can communicate with each other.

  The spool 36 moves up and down with respect to the left and right movement of the rod 3 as described above. However, in the illustrated case, when the rod 3 moves to the left and the piston 2 is displaced within a predetermined stroke range, the groove 39 is formed. The one pressure chamber R1 and the other pressure chamber R2 communicate with each other so as to face the annular groove 29 and the annular groove 31, and conversely, the rod 3 moves to the right in FIG. 1 so that the piston 2 is within a predetermined stroke range. When displaced, the groove 38 is set so as to face the annular groove 27 and the annular groove 29 so as to communicate with one pressure chamber R1 and the other pressure chamber R2, and when the piston 2 is not within a predetermined stroke range. Neither groove 38, 39 prevents the annular groove 29 from communicating with the annular grooves 27, 31.

  When the piston 2 moves to the left, the damping valve 6 opens and the liquid passes through the flow path 4 and moves from one pressure chamber R1 to the other pressure chamber R2.

  At this time, the shock absorber D1 generates a damping force commensurate with the pressure loss generated when the liquid passes through the damping valve 6.

  The piston 2 continues to move to a position where the spool 36 is pushed up by a distance H1 between the upper end of the groove 39 and the lower end of the annular groove 29 from the relationship with the inclination angle θ with respect to the axis of the tapered portion 19 of the rod 3. When the piston 2 is displaced, the groove 39 communicates with the annular groove 29 and the annular groove 31, and the pressure in the pressure chamber R1 is larger than the pressure in the pressure chamber R2. 17 is opened to flow from the pressure chamber R1 into the pressure chamber R2.

  That is, when the spool 36 rises by a distance H1 or more due to the displacement of the piston 2 to the left, the groove 39, the annular grooves 29 and 31, the passages 13 and 14, the communication passage 15 and the communication passage 16 are bypassed. The bypass path is formed, and the two pressure chambers R1 and R2 are communicated with each other through the bypass path.

  Accordingly, the liquid in the pressure chamber R1 moves into the pressure chamber R2 not only through the flow path 4 but also through the bypass path. Therefore, if the piston 2 is displaced to the extent that the spool 36 is pushed up by the distance H1 or more, the shock absorber The damping force generated by D1 is low.

  Further, when the piston 2 is displaced to the right in the figure after the piston 2 is displaced to the predetermined stroke range, the pressure in the pressure chamber R2 becomes larger than the pressure in the pressure chamber R1. Since the liquid cannot push open the check valve 17, a bypass path is not formed.

  Then, the liquid flows from the pressure chamber R2 into the pressure chamber R1 through the flow path 5 and passes through the damping valve 7. Therefore, when the piston 2 is displaced to the right after being displaced to the left, A high damping force will be generated.

  Conversely, when the piston 2 moves to the right, the damping valve 7 opens and the liquid passes through the flow path 5 and moves from the other pressure chamber R2 to the one pressure chamber R1.

  At this time, the shock absorber D1 generates a damping force commensurate with the pressure loss generated when the liquid passes through the damping valve 7.

  The position where the piston 2 continues to move and lowers the spool 36 by a distance H2 between the lower end of the groove 38 and the upper end of the annular groove 29 from the relationship with the inclination angle θ with respect to the axis of the tapered portion 19 of the rod 3. When the piston 2 is displaced up to, the groove 38 communicates with the annular groove 27 and the annular groove 29, and the pressure in the pressure chamber R2 is larger than the pressure in the pressure chamber R1, so that the liquid is a check provided in the communication path 15. The valve 18 is pushed open to flow from the pressure chamber R2 into the pressure chamber R1.

  That is, when the spool 36 is lowered by the distance H2 or more due to the displacement of the piston 2 to the right, the groove 38, the annular grooves 27 and 29, the passages 13 and 14, the communication passage 15 and the communication passage 16 are bypassed. The bypass path is formed, and the two pressure chambers R1 and R2 are communicated with each other through the bypass path.

  Accordingly, the liquid in the pressure chamber R2 moves into the pressure chamber R1 not only through the flow path 5 but also through the bypass path, so that if the piston 2 is displaced to the extent that the spool 36 is lowered by the distance H1 or more, the buffering is performed. The damping force generated by the device D1 is low.

  Furthermore, when the piston 2 is displaced to the left in the figure after the piston 2 is displaced within the predetermined stroke range, the pressure in the pressure chamber R1 becomes larger than the pressure in the pressure chamber R2 this time. Since the liquid cannot push open the check valve 18, a bypass path is not formed.

  Then, the liquid flows from the pressure chamber R1 into the pressure chamber R2 via the flow path 4 and passes through the damping valve 6. Therefore, when the piston 2 is displaced to the right after being displaced to the left, A high damping force will be generated.

  Therefore, the predetermined stroke range when the piston 2 moves to the left is determined by the distance H1 between the lower end of the groove 38 and the upper end of the annular groove 29 and the inclination angle θ with respect to the axis of the tapered portion 19, The predetermined stroke range when the piston 2 moves to the right is determined by the distance H2 between the upper end of the groove 39 and the lower end of the annular groove 29 and the inclination angle θ with respect to the axis of the tapered portion 19.

  Therefore, the predetermined stroke range in this case is the range in which the piston 2 displacement is greater than the distance H1 / tanθ when the piston 2 moves to the left from the neutral position, and the piston 2 when the piston 2 moves to the right from the neutral position. The displacement is in the range of distance H2 / tan θ or more.

  That is, the damping characteristic of the shock absorber D1 draws a hysteresis loop as shown in FIG. 3, and this shock absorber D1 has a so-called position-dependent shock absorber having a damping characteristic depending on the piston displacement. Function as.

  It continues and demonstrates the effect | action of the buffer D1 comprised as mentioned above. The shock absorber D1 is interposed between the attachment portions A1 and A2 as described above. When the shock absorber D1 is attached to the space between the attachment portions A1 and A2, the piston 2 is in the center with respect to the cylinder 1. Assume a case where it is not arranged.

  For example, when the interval between the attachment parts A1 and A2 is narrower than the reference attachment length of the shock absorber D1, the piston 2 neutral position is from the left in FIG.

  Therefore, in this case, the spool 36 looks like the rod 3 has moved to the left. Therefore, the spool 36 is slid on the tapered portion 19 of the rod 3 and pushed upward.

  Then, in this state, for example, the bypass path is formed before the piston 2 moves to the left by the distance H1 / tanθ from the neutral position where the piston 2 is shifted to the left. On the contrary, from the neutral position where the piston 2 is shifted to the left Even if the piston 2 moves to the right by the distance H2 / tan θ, the bypass path is not formed.

  Here, as described above, since the sleeve 25 is movable in the vertical direction with respect to the housing 10, if the distance that the piston 2 is shifted to the left is w, the sleeve 25 is moved to the housing 10 by wtan θ. When the piston 2 is moved upward and fixed at that position, the positional relationship between the sleeve 25 and the spool 36 can be the same as when the piston 2 is in the neutral position at the reference mounting length.

  That is, even if the neutral position of the piston 2 when the shock absorber is mounted deviates from the neutral position of the reference mounting length, the predetermined stroke range is adjusted by moving the sleeve 25 up and down with respect to the housing 10 as described above. Even if the mounting length does not become the reference mounting length, in short, even if the piston neutral position is shifted from the center of the cylinder 1 when the shock absorber D1 is mounted on the mounting portions A1 and A2, it is attenuated. The predetermined stroke range for changing the force can be set similarly to the case where the mounting length is the reference mounting length.

  Therefore, in the present invention, the mounting work of the shock absorber D1 to the mounting portions A1 and A2 is drastically compared with the conventional shock absorbers whose mounting length must be strictly the reference mounting length. It can be made simple and easy.

  Further, since the position of the sleeve 25 can be adjusted without requiring a large force, the shock absorber is attached to the attachment site even when the shock absorber is large or the mounting space is small. The adjustment work can be completed in the state, and the position adjustment work becomes very easy.

  Furthermore, even in a situation where the shock absorber must be maintained in a compressed state during the shock absorber mounting operation, if the damping force is set low by adjusting the position of the sleeve 25, Since the maintenance of the compressed state becomes very easy, the attachment work can be facilitated also in this respect.

  Further, as shown in FIG. 2, the position adjustment of the sleeve 25 with respect to the housing 10 when the neutral position of the piston 2 at the time of mounting the shock absorber deviates from the neutral position at the reference mounting length is performed in advance. By measuring the distance t from the lower end of the sleeve 25 to the taper portion 19 while maintaining a positional relationship in which a predetermined stroke range is correctly set, the following can be easily performed. .

  First, as shown by the one-dot chain line in FIG. 2, the sleeve 25 is once lowered until it comes into contact with the taper portion 19, and then the sleeve 25 is raised by the distance t to complete the adjustment operation.

  That is, since the inclination angle θ of the taper portion 19 does not change in the middle, and the arrangement of the spool 36 and the sleeve 25 in the left-right direction in FIG. 3 is unchanged, even if the rod 3 moves in the left-right direction, the lower end of the sleeve 25 This is because the axial position of the spool 36 with respect to the sleeve 25 is always constant if the distance between the rod 3 and the tapered portion 19 of the rod 3 is maintained to be the distance t.

  Therefore, by setting the lower end of the sleeve 25 so that the shock absorber D1 is attached to the attachment portion so as to be brought into contact with the tapered portion 19 which is the inclined surface of the rod 3, the shock absorption of the piston 2 is set. This makes it easy to adjust the position of the sleeve 25 with respect to the housing 10 when the neutral position at the time of mounting the device is shifted from the neutral position at the reference mounting length.

  Since the distance H1 and the distance H2 can be changed depending on the position of the sleeve 25 with respect to the housing 10, the predetermined stroke range in which the damping force is changed can be adjusted by adjusting the position where the bypass path is formed. It is possible to make the attenuation characteristics generated when the shock absorber D1 operates right and left different.

  Of course, if the spool 20 is positioned so that the distance H1 and the distance H2 are the same, the damping characteristics generated when the shock absorber D1 is operated to the left and right can be made the same.

  In addition, the directions of the check valves 17 and 18 are reversed, that is, in the middle of the communication path 15, the check valves 17 and 18 are back-to-back on both sides with the connection portion with the communication path 16 as a boundary. In this case, the predetermined stroke range can be set so that the bypass path is formed when the piston displacement is reversed after the piston 2 moves to the left and right sides of the shock absorber. Furthermore, the directions of the check valves 17 and 18 can be set so as to be in the same direction with respect to the communication path 15.

  Further, a predetermined stroke range can be set without providing the annular grooves 27, 29, 31. However, by providing the annular grooves 27, 29, 31, the grooves 38, 39 are formed into the annular grooves 27, 29, 31. Since the bypass path is formed when wrapping at 31, the predetermined stroke range can be set wider accordingly.

  Further, the grooves 38 and 39 formed in the spool 36 may have any shape, and a plurality of grooves having the same role in the circumferential direction may be provided.

  Further, the depth and the opening area may be changed in the axial direction of the grooves 38 and 39 in order to make the damping force variable according to the piston displacement.

  For positioning and fixing the sleeve 25, other methods may be used regardless of screw fixing.

  Next, the shock absorber D2 in the second embodiment shown in FIG. 4 will be described. It should be noted that the same members as those in the shock absorber D1 of the above-described embodiment are simply denoted by the same reference numerals, and the detailed description thereof will be omitted below, and the first of the shock absorber D2 in the second embodiment will be mainly described. The difference from the shock absorber D1 in the first embodiment will be described.

  The shock absorber D2 has a connection between a spool 50 movably inserted into the cylinder 1 and passages respectively communicating with the annular grooves 26, 28, 30 of the sleeve 25 provided in the housing 10. Different from the shock absorber D1 in the form.

  Hereinafter, the different parts will be described in detail. The spool 50 includes a cylindrical main body 51, a groove 52 formed on a side portion of the main body 51, and a spherical shape provided so as to protrude from the lower end of the main body 51. It is comprised with the convex part 53, and only one groove | channel is provided in 2nd Embodiment.

  Of the passages provided in the housing 10, a passage 61 that faces the annular groove 26 of the sleeve 25 and a passage 62 that faces the annular groove 30 communicate with the other pressure chamber R <b> 2 and face the annular groove 28. The passage 63 communicates with one pressure chamber R1.

  The sleeve 25 is positioned with respect to the housing 10 so that the groove 52 of the spool 50 faces only the annular groove 28 at the neutral position of the piston 2 when the shock absorber is attached.

  Therefore, when the piston 2 is in the neutral position, the groove 52 and the passages 61, 62, 63 are not communicated with each other, and a bypass passage that bypasses the flow passages 4, 5 is not formed.

  On the other hand, since the piston 2 is displaced to the left from the neutral position and the groove 52 of the spool 50 is opposed to the annular groove 27 and the annular groove 29, the displacement distance of the piston 2 from the neutral position is the groove. 52, the distance H3 between the upper end of 52 and the lower end of the annular groove 27 is equal to or greater than the distance obtained by dividing tan θ. Is a range where the displacement distance from the neutral position is equal to or greater than the distance obtained by dividing the distance H4 between the lower end of the groove 52 and the upper end of the annular groove 31 by tan θ.

  In this case as well, the axial positional relationship between the sleeve 25 and the spool 50 can be adjusted by moving the sleeve 25 in the vertical direction with respect to the housing 10.

  That is, by moving the sleeve 25 in the vertical direction with respect to the housing 10, it is possible to adjust a predetermined stroke range in which the damping force is changed. Even in the shock absorber D2, the mounting length is equal to the reference mounting length. Even if it is not possible, that is, even if the piston neutral position does not become the center of the cylinder 1, the predetermined stroke range for changing the damping force can be set similarly to the case where the mounting length is the reference mounting length. it can.

  Therefore, as in the first embodiment, the mounting operation of the shock absorber D2 to the mounting portions A1 and A2 is less than that of the conventional shock absorber in which the mounting length must be strictly the reference mounting length. It can be greatly simplified and made easy.

  Note that, in the present embodiment, the description is given on the assumption that the shock absorber is used as a vibration damping device. However, the shock absorber of the present invention can be used for vehicles, devices, etc. in addition to structures. It is natural.

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

It is sectional drawing of the shock absorber in 1st Embodiment. It is a partial expansion longitudinal cross-sectional view of the buffer in 1st Embodiment. It is a figure which shows the attenuation | damping characteristic of the buffer in 1st Embodiment. It is a longitudinal cross-sectional view of the buffer in 2nd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cylinder 2 Piston 3 Rod 4, 5 Flow path 6, 7 Damping valve 8 Cylinder 9 Hole 10 Housing 11 Guide hole 12 Hollow part 13, 14, 61, 62, 63 Passage 15 Communication path 16 Communication path 17, 18 Check valve 19 Tapered portion 20 Screw groove 25 Sleeve 26, 27, 28, 29, 30, 31 Annular groove 32, 33, 34 Hole 35 Screw thread 36, 50 Spool 37, 51 Main body 38, 39, 52 Groove 40, 53 Convex portion 41 Springs A1 and A2 as biasing means B1 and B2 Ball joints D1 and D2 Shock absorber N Nut R1 One pressure chamber R2 The other pressure chamber T Adjusting means

Claims (4)

A cylinder, a piston that is slidably inserted into the cylinder, two pressure chambers partitioned by the piston in the cylinder, and a rod connected to the piston change the damping force within a predetermined stroke range. The shock absorber is provided with an adjusting means for adjusting the predetermined stroke range, and the adjusting means is movably inserted into the hollow portion of the housing having a hollow portion communicating with the two pressure chambers. And a spool having a groove on the outer peripheral side, slidably inserted into the sleeve, and having a tip abutting against an inclined surface provided on the rod and inclined with respect to the axis of the rod, and a spool And an urging means for urging the rod toward the rod, and within a predetermined stroke range, the spool groove has an opening in the passage communicating with the inside of the sleeve and one of the pressure chambers and the spool. Buffer, characterized in that is opposed to over blanking the and the other pressure chamber to the opening of the passage communicating. Three annular grooves along the circumferential direction are formed on the inner circumferential side of the sleeve, the annular groove located on one end side communicates with one pressure chamber, and the annular groove located on the other end side communicates with the other pressure chamber. The annular groove located in the middle communicates with one pressure chamber and the other pressure chamber, and between the annular groove located in the middle and the one pressure chamber and between the annular groove located in the middle and the other pressure chamber. 2. The shock absorber according to claim 1, further comprising a check valve provided therebetween . The shock absorber according to claim 1 or 2, wherein the inclined surface is a tapered portion provided in an annular shape on the rod . The shock absorber according to any one of claims 1 to 3, wherein the tip of the sleeve can be brought into contact with the inclined surface in a state of being attached to the attachment portion .

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