JP2011017405A - Shock absorber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a shock absorber achieving miniaturization by integrating two juxtaposed shock absorbers and also achieving simple assembly operation.SOLUTION: In this shock absorber D, a cylinder assembly to be integrated includes: a cylinder 1; a rod 2 movably inserted into the cylinder 1; a hollow rod 3 movably inserted into the cylinder 1 and also movably mounted on the periphery of the rod 2; a piston 4 arranged around the periphery of the rod 2 or hollow rod 3, slidably inserted into the cylinder 1, and partitioning the inside of the cylinder 1 into a rod chamber R1 and a piston chamber R2; an annular member 8 on the side of the rod chamber, fixed to the end of the cylinder 1 on the side of the rod chamber and inserting the hollow rod 3 into its inner side; and an annular member 12 on the side of the piston chamber, fixed to the end of the cylinder on the side of the piston chamber. The cylinder assembly is stored in an outer cylinder 6 forming a reservoir R between the cylinder 1 and the outer cylinder.

Description

  The present invention relates to an improved shock absorber.

  As this kind of shock absorber, in general, a cylinder, a piston that is slidably inserted into the cylinder and divides two pressure chambers in the cylinder, and is movably inserted into the cylinder and connected to the piston For example, in the case of a vehicle suspension application, it is interposed between the vehicle body and the axle and used for the purpose of attenuating the vibration of the vehicle body that is the object of vibration control. .

  As a suspension, there is a proposal of an active suspension in which a hydraulic cylinder is interposed between the vehicle body and the axle, and the vehicle height is positively adjusted by the hydraulic cylinder to suppress the vehicle body vibration. In some cases, a shock absorber is interposed between the vehicle body and the axle together with the hydraulic cylinder so that the vibration of the vehicle body is assisted by the shock absorber (see, for example, Patent Document 1).

Japanese Utility Model Publication No. 03-118106

  By the way, in the above-described active suspension, a hydraulic cylinder is used for vehicle height adjustment, but there are cases where it is desired to use an electric actuator which is excellent in terms of responsiveness.

  An electric actuator is advantageous in terms of responsiveness as described above, but unlike a hydraulic cylinder, it dislikes the input of high-frequency vibration. Therefore, it is desirable to insulate high-frequency vibration input to the actuator. It is difficult to suppress high-frequency vibration input to the actuator. Therefore, it is conceivable that a shock absorber that absorbs high-frequency vibrations is connected in series to the actuator in addition to the shock absorber described above.

  In this way, it is possible to adjust the vehicle height with good responsiveness while suppressing vibration input to the actuator. However, a shock absorber connected in series to the actuator and a shock absorber parallel to the actuator can be used. Two shock absorbers are required, and the entire apparatus as an active suspension becomes large.

  In addition to the vehicle suspension application described above, the same can be said for the case where two shock absorbers are used in parallel, and there is a problem that the apparatus including the two shock absorbers is enlarged.

  On the other hand, if a structure is adopted in which two shock absorbers are integrated by sharing a cylinder by using two shock absorber cylinders in common and allowing two rods to enter and exit from the cylinder. Although the size of the device can be reduced, the structure is complicated and the assembly work may be complicated as compared with a normal shock absorber.

  Therefore, the present invention was created in consideration of the above-mentioned problems, and the object of the present invention is to reduce the size by integrating two shock absorbers arranged in parallel and to perform a simple buffering operation. Is to provide a vessel.

  In order to achieve the above-described object, a shock absorber in the problem solving means of the present invention includes a cylinder, a rod that is movably inserted into the cylinder, a movably inserted into the cylinder, and an outer periphery of the rod. A hollow rod that is movably mounted on the rod, a piston that is provided on the outer periphery of the rod or the hollow rod and that is slidably inserted into the cylinder to partition the rod chamber and the piston chamber in the cylinder, and the rod chamber side of the cylinder A cylinder assembly integrated with a cylinder including a rod chamber-side annular member that is fixed to the end and through which a hollow rod is inserted, and a piston chamber-side annular member that is fixed to a piston chamber-side end of the cylinder. It is characterized by being housed in an outer cylinder that forms a reservoir between them.

  According to the shock absorber of the present invention, two parallel shock absorbers are integrated by sharing one cylinder, and function as two parallel shock absorbers, so that the entire apparatus becomes small.

  Then, in a state where the rod chamber side annular member, the piston chamber side annular member, the piston, the rod, the hollow rod and the coil spring, and the respective cushions are accommodated in the cylinder, the cylinder is integrated into one cylinder. Since the assembly is formed and the cylinder assembly is accommodated in the outer cylinder, the assembly work to the outer cylinder is easy, and the manufacturing efficiency of the shock absorber is improved.

It is a longitudinal cross-sectional view of the shock absorber in one embodiment of the present invention.

  The present invention will be described below based on the embodiments shown in the drawings. As shown in FIG. 1, the shock absorber D is a cylinder 1, a rod 2 that is movably inserted into the cylinder 1, a movably inserted into the cylinder 1, and moves to the outer periphery of the rod 2. A hollow rod 3 that is freely mounted, a piston 4 that is provided on the outer periphery of the rod 2 and that is slidably inserted into the cylinder 1 to partition the rod chamber R1 and the piston chamber R2 into the cylinder 1; A long outer cylinder 6 that covers the outer periphery of the cylinder 1 and forms an annular gap 5 between the cylinder 1 and the rod chamber side end 6a of the outer cylinder 6 is closed, and the outer periphery of the hollow rod 3 is pivotally supported. The rod guide 7, the rod chamber side annular member 8 that is fixed to the rod chamber side end 1 a of the cylinder 1 and through which the hollow rod 3 is inserted, and the rod chamber side annular member 8 and the rod guide 7 are interposed between them. Inside It is constituted by a cylindrical member 9 which the rod 3 is inserted.

  In the shock absorber D, a reservoir R is formed by the space 10 formed by the rod guide 7, the cylinder member 9, the rod chamber side annular member 8, and the outer cylinder 6, and the annular gap 5, and the cylinder 1 The inside is filled with working oil as working fluid, and the reservoir R is filled with gas in addition to working oil. In addition to the working oil, the working fluid may be a liquid such as water or an aqueous solution.

  More specifically, the cylinder 1 is cylindrical, and an annular rod chamber side annular member 8 is fitted to the inner periphery of the rod chamber side end portion 1a which is the upper end in FIG. An annular piston chamber side annular member 12 is fitted to the inner periphery of the piston chamber side end 1b. The rod chamber-side annular member 8 is fixed to the cylinder 1 by caulking the rod chamber-side end 1a of the cylinder 1, and conversely, the piston chamber-side annular member 12 is similarly the piston chamber-side end 1b of the cylinder 1. Is fixed to the cylinder 1 by caulking. The rod chamber side annular member 8 and the piston chamber side annular member 12 are urged in a direction protruding from the cylinder 1 by coil springs 34 and 35 described later, so that the rod side end 1a and the piston side end 1b of the cylinder 1 are biased. The rod chamber-side annular member 8 and the piston chamber-side annular member 12 can be fixed by caulking that each bends inward, but the rod-side end 1a and the piston-side end 1b are fixed to the cylinder 1 so that they cannot move. For example, a method other than caulking of the rod side end 1a and the piston side end 1b, for example, the rod chamber side annular member 8 and the piston chamber side annular member 12 are respectively connected to the inner circumferences of the rod side end 1a and the piston side end 1b. You may make it screw.

  The cylinder 1 configured as described above is accommodated in the outer cylinder 6 longer than the cylinder 1 as described above, and the annular rod guide 7 and the cylinder member 9 which are fitted to the upper end of the outer cylinder 6 in FIG. And a cap 11 that closes the lower end of the outer cylinder 6 in FIG. 1 and is fixed to the outer cylinder 6.

  When the cylinder 1 is accommodated and fixed in the outer cylinder 6 in this way, an annular gap 5 is provided between the cylinder 1 and the outer cylinder 6, and the outer cylinder 6, rod guide 7, cylinder member 9, and rod A space 10 is provided by the chamber-side annular member 8, and a reservoir R is formed by the annular gap 5 and the space 10. The reservoir R is provided to compensate for a volume change that occurs in the cylinder 1 as the rod 2 and the hollow rod 3 enter and exit the cylinder 1.

  The cylindrical member 9 has an inner diameter larger than the outer diameter of the seal case 18 provided at the lower end in FIG. 1 of the hollow rod 3 to be described later, and hinders the vertical movement in FIG. There is no. In this limit, the volume of the reservoir R can be increased by setting the outer diameter of the cylindrical member 9 as small as possible.

  Thus, by forming the reservoir R using the space 10 as well as the annular gap 5, even if the diameter of the outer cylinder 6 is set to a small diameter, a sufficient volume of the reservoir R can be secured, and the buffer The outer diameter of the vessel D can be reduced.

  An annular seal case 13 is fitted to the inner periphery of the rod chamber side end 6 a that is the upper end in FIG. 1 of the outer cylinder 6, and the rod guide 7 is fitted and fixed to the inner periphery of the seal case 13. Yes. Specifically, the seal case 13 is fixed to the outer cylinder 6 by welding or the like, and connected to the inner periphery from the upper end of the cylinder portion 13a toward the inner peripheral side with the cylindrical portion 13a in which the rod guide 7 is fitted to the inner periphery. And an annular flange portion 13b that comes into contact with the upper end of the rod guide 7 and a holding portion 13c that rises from the inner periphery of the flange portion 13b and holds the annular seal member 17, and is hollow inserted through the inner periphery side. The outer periphery of the hollow rod 3 is sealed by bringing the seal member 17 into sliding contact with the outer periphery of the rod 3. The rod guide 7 fitted to the inner periphery of the seal case 13 has an annular shape and includes a cylindrical bush 16 slidably contacting the outer periphery of the hollow rod 3 on the inner periphery. The hollow rod 3 is positioned in the radial direction with respect to the outer cylinder 6 and the cylinder 1 while allowing sliding.

  As described above, the hollow rod 3 is pivotally supported by the rod guide 7 via the bush 16, and the lower end in FIG. 1 is movably inserted into the cylinder 1. In this case, a flange 3a is provided at the upper end of the hollow rod 3 in FIG. 1, and the hollow rod 3 can be connected to a vibration suppression target via the flange 3a. In attaching the hollow rod 3 to the vibration suppression target, an attachment member suitable for the vibration suppression target may be used, and the hollow rod 3 is not limited to the flange 3a.

  The rod 2 is inserted into the hollow rod 3 and is provided with a screw portion 2b at the upper end in FIG. 1 so that the screw portion 2b can be connected to a vibration control target. A small diameter portion 2a is formed. The rod 2 is screwed with a cylindrical seal case 18 holding an annular seal member 19 at the lower end in FIG. 1 of the hollow rod 3, and the seal member 19 is in sliding contact with the outer periphery of the rod 2. 2 is sealed. In addition, a bush 20 that slides on the outer periphery of the rod 2 is provided on the inner periphery of the lower end of the seal case 18. The rod 2 is allowed to slide in the axial direction of the rod 2 while allowing the rod 2 to slide in the axial direction. Positioning. In addition, a flange 3b is provided on the outer periphery of the lower end of the hollow rod 3, and a cushion 39 mounted on the outer periphery of the hollow rod 3 is mounted on the upper right end of the flange 3b in FIG. When the rod 3 moves upward in FIG. 1 with respect to the cylinder 1, it finally collides with the rod guide 7 to restrict further upward movement of the hollow rod 3 and to reduce the impact. . That is, the cushion 39 sets the upper limit of movement of the hollow rod 3 relative to the cylinder 1.

  Thus, the rod 2 can move relative to the cylinder 1 and the hollow rod 3 in the vertical direction in FIG. 1, which is the axial direction. Since it is supported and can move relative to the cylinder 1 and the rod 2 in the up and down direction in FIG. 1, the rod 2 and the hollow rod 3 can move up and down independently of the cylinder 1. Can be done.

  A piston 4 is attached to the small diameter portion 2a at the lower end in FIG. The piston 4 is slidably inserted into the cylinder 1 to partition the rod chamber R1 and the piston chamber R2 in the cylinder 1.

  Specifically, the piston 4 includes a cylindrical collar 21 attached to the outer periphery of the small-diameter portion 2a of the rod 2 and an annular valve disk whose axial length is shorter than the collar 21 attached to the outer periphery of the collar 21. 22 and a sliding contact body 23 that holds the outer periphery of the valve disk 22 and is slidably contacted with the inner periphery of the cylinder 1 and fixed to the small diameter portion 2 a of the rod 2. The collar 21 is directly assembled to the small-diameter portion 2a of the rod 2 and fixed to the rod 2 with a piston nut 30 that is also screwed to the small-diameter portion 2a, and the valve disk 22 is attached to the rod 2 via the sliding contact body 23. It is designed to be connected. Thus, by fixing the sliding contact body 23 with the collar 21, the valve disk 22 can be connected to the rod 2 by the sliding contact body 23, but the collar 21 is integrated with the piston nut 30. Also good.

  The valve disk 22 includes passages 22a and 22b that communicate the rod chamber R1 and the piston R2. The passage 22a is stacked at the lower end of the valve disc 22 and is opened and closed by a check valve 24 urged from the back toward the valve disc 22 by a spring 25, and only the flow of hydraulic oil from the rod chamber R1 toward the piston chamber R2 is performed. Is set to allow one-way operation, and resistance is given to the flow of hydraulic oil through which the passage 22a itself passes. The passage 22b is stacked at the upper end of the valve disc 22 and is opened and closed by a check valve 26 urged from the back toward the valve disc 22 by a spring 27, and only the flow of hydraulic oil from the piston chamber R2 toward the rod chamber R1 is performed. Is set so as to allow the flow of hydraulic oil, and resistance is given to the flow of hydraulic fluid through which the passage 22b itself passes. In addition, in order to give resistance more than the flow path resistance of the passages 22a and 22b, an annular leaf valve whose outer periphery is held on the sliding contact body 23 and set to be opened in the same manner as the valve disk 22 is laminated. Also good.

  The sliding contact body 23 has an annular plate 23a fitted to the small-diameter portion 2a of the rod 2 and a cylindrical holding body in which the valve disk 22 is mounted on the inner periphery depending from the outer periphery of the plate 23a downward in FIG. Part 23b, a cylindrical part 23c that rises upward from the outer periphery of the plate 23a in FIG. 1, and a flange-like sliding contact ring 23d that is provided on the outer periphery from the upper end of FIG. It is configured with.

  More specifically, the plate 23a is provided with a through hole 23e that allows the rod chamber R1 and the piston chamber R2 to communicate with each other, and the passages 22a and 22b provided in the valve disk 22 fixed to the inner periphery of the holding portion 23b are through holes. It communicates with the rod chamber R1 through 23e.

  Further, a cylindrical cushion 31 mounted on the outer periphery of the rod 2 is laminated on the upper end of the plate 23a. The cushion 31 has its upper end opposed to the lower end of the seal case 18 provided at the lower end of the hollow rod 3. When the rod 2 is moved upward in FIG. Is engaged with the seal case 18 to restrict the upward movement of the rod 2 relative to the hollow rod 3 and to mitigate the impact. That is, the cushion 31 restricts the movement limit of the rod 2 and the hollow rod 3 in the approaching direction.

  The holding portion 23b is formed with a step portion 23f that fits the shoulder portion of the valve disc 22 at the outer periphery of the upper end in FIG. 1 on the inner periphery, and is mounted in an annular groove 23g provided on the inner periphery in the same manner as the step portion 23f. The snap ring 28 sandwiches the valve disc 22 fitted to the inner periphery, and holds and holds the valve disc 22 inside.

  Thus, since the valve disk 22 is held by the sliding contact body 23 on the piston chamber side and is connected to the rod 2 via the sliding contact body 23, the rod 2 and the hollow rod 3 Even when a large axial force (axial force) is applied to the sliding contact body 23 through the cushion 31 when the slidable contact member 23 approaches, the check valves 24 and 26 and the valve disk 22 on which these are stacked can be protected, and the hollow A situation in which the valve disk 22 is distorted due to repeated collisions between the rod 3 and the cushion 31 and the generated damping force of the shock absorber D does not deviate from the initial setting.

  Furthermore, since the valve disc 22 is held using the sliding contact body 23, a general-purpose piston can be used for the valve disc 22, and the check valve 24 stacked on the valve disc 22 and the valve disc 22 is used. , 26 is not increased in size, so that the manufacturing cost can be reduced.

  Further, by holding the valve disc 22 with the sliding contact 23, it is possible to avoid the input of axial force to the valve disc 22, so that the cushion 31 can be laminated on the sliding contact 23, and the valve disc 22. There is also an advantage that the axial length of the piston portion including the sliding contact body 23 and the cushion 31 can be shortened.

  A stopper 29 facing the cushion 32 fixed to the upper end of the piston chamber side annular member 12 fixed to the lower end of the cylinder 1 is attached to the lower end of the holding portion 23b. When the rod 2 moves downward in FIG. 1 with respect to the cylinder 1, the cushion 32 finally abuts against the stopper 29 to restrict further downward movement of the rod 2, and impact To ease. That is, the cushion 32 sets a lower limit of movement of the rod 2 relative to the cylinder 1. As described above, the valve disk 22 is housed and held in the holding portion 23b, and the stopper 29 that abuts the cushion 32 provided in the piston chamber R2 of the cylinder 1 is provided at the piston chamber side end of the holding portion 23b. Therefore, even if the rod 2 penetrates into the cylinder 1 to the deepest depth, the valve disk 22 is prevented from interfering with other members by the holding portion 23b, and is protected from an impact at the time of the most contraction.

  Returning, the slidable contact ring 23d has an annular groove 23h on the outer periphery, and a piston ring 33 that is in slidable contact with the inner periphery of the cylinder 1 is mounted in the annular groove 23h. Further, a coil spring 34 accommodated in the rod chamber R1 is interposed between the sliding contact ring 23d and the rod chamber side annular member 8, and between the sliding contact ring 23d and the piston chamber side annular member 12. The coil spring 35 accommodated in the piston chamber R2 is interposed, and the piston 4 is sandwiched and energized by the coil springs 34 and 35 from both the upper and lower sides. It is positioned at a predetermined neutral position where the urging forces of 34 and 35 are balanced. When the piston 4 is displaced with respect to the cylinder 1, the coil springs 34 and 35 are configured to return the piston 4 to the neutral position by the biasing force. Note that the neutral position is not necessarily set at the center of the cylinder 1. By providing the coil springs 34 and 35, it is possible to prevent the piston 4 from being disposed at the uppermost position or the lowermost position with respect to the cylinder 1 so that vibration cannot be absorbed. Further, in this case, since the coil springs 34 and 35 are accommodated in the cylinder 1, the positioning coil spring 34 is not enlarged without increasing the size of the shock absorber D in which the rod 2 and the hollow rod 3 operate independently. , 35 can be provided.

  Further, the rod chamber side annular member 8 fixed to the inner periphery of the rod chamber side end portion 1a serving as the upper end of the cylinder 1 includes a cylinder portion 8a fitted to the inner periphery of the cylinder 1, and an upper end of the cylinder portion 8a. A flange-shaped spring receiving portion 8b that protrudes inward on the inner periphery is configured, and the upper end of the coil spring 34 is supported by the spring receiving portion 8b. An annular cushion 38 that is fitted to the inner periphery of the cylinder 1 is laminated at the lower end in FIG. 1 of the cylindrical portion 8a. As it moves upward, it finally abuts against the sliding contact ring 23d to restrict further upward movement of the rod 2 and alleviate the impact. That is, the cushion 38 sets an upper limit of movement of the rod 2 relative to the cylinder 1.

  In this manner, the rod chamber side annular member 8 and the piston chamber side annular member 12 are fixed to the upper and lower opening ends of the cylinder 1, so that the piston 4, the rod 2, the hollow rod 3, and the coil spring 34 are placed in the cylinder 1. , 35, in a state in which the cushions 31, 32, 38, 39 are accommodated, these can be integrated into the cylinder 1 to form one cylinder assembly C, so that the assembly work to the outer cylinder 6 is easy. Manufacturing efficiency is improved.

  Even when the coil springs 34 and 35 are configured to be accommodated in the rod chamber R1 and the piston chamber R2, the rod chamber side annular member that functions as a spring receiver for the coil spring 34 at the upper and lower opening ends of the cylinder 1. 8 and the piston chamber-side annular member 12 that functions as a spring receiver for the coil spring 35 are fixed, so that it is not necessary to compress the coil springs 34 and 35 when assembled to the outer cylinder 6.

  In turn, a partition member 15 is interposed between the piston chamber side annular member 12 provided at the lower end of the cylinder 1 and the cap 11 closing the lower end in FIG. 1 is partitioned by the partition member 15.

  In addition, the partition member 15 includes passages 15a and 15b that allow the reservoir R and the piston chamber R2 to communicate with each other. As described above, the upper end outer shoulder is fitted to the inner periphery of the piston chamber-side annular member 12. ing. Thus, since the piston chamber side annular member 12 is provided in the piston chamber side end 1b of the cylinder 1 and the partition member 15 is fitted to the piston chamber side annular member 12, only the rod 2 is used. Instead of adjusting the outer diameter of the partition member 15 to the cylinder diameter that tends to increase the diameter by inserting the hollow rod 3, the piston member side annular member 12 having a uniform inner diameter is used for the partition member 15. The bale valve valve disk currently used can be utilized, and there exists a merit which can reduce manufacturing cost.

  Further, the passage 15a is opened and closed by a check valve 36 stacked on the upper end of the partition member 15. The check valve 36 allows only the flow from the reservoir R to the piston chamber R2. Yes. Further, the passage 15b is opened and closed by a leaf valve 37 stacked on the lower end of the partition member 15, is allowed to flow only from the piston chamber R2 toward the reservoir R, and passes through the passage 15b. The leaf valve 37 provides resistance to the flow of hydraulic oil.

  Next, the operation of the shock absorber D configured as described above will be described. As described above, the rod 2 and the hollow rod 3 can move relative to each other in the vertical direction in FIG. 1, which is the axial direction, and also relative to the cylinder 1 in the vertical direction in FIG. 1. The rod 2 and the hollow rod 3 can be displaced in the vertical direction in FIG.

  When the rod 2 is not displaced with respect to the cylinder 1 and only the hollow rod 3 moves downward with respect to the cylinder 1, the hydraulic oil in the rod chamber R <b> 1 accompanies the penetration of the hollow rod 3 into the cylinder 1. Flows out to the reservoir R through the passage 22 a provided in the piston 4 and the passage 15 b provided in the partition member 15. In order to give resistance to the flow of the hydraulic oil by the passage 22a and the leaf valve 37, the pressure in the rod chamber R1 rises, and the hollow rod 3 receives the pressure in the rod chamber R1, and thereby the above-described lower portion of the hollow rod 3 The movement to is suppressed.

  Further, when the rod 2 is not displaced with respect to the cylinder 1 and only the hollow rod 3 moves upward with respect to the cylinder 1, a passage provided in the piston 4 with the withdrawal of the hollow rod 3 from the cylinder 1. The hydraulic oil is supplied from the reservoir R into the rod chamber R1 whose volume is increased through the passage 15a provided in the partition member 15 and 22b. Since the check valve 36 is opened in the piston chamber R2, it is maintained at the same pressure as the reservoir R. However, in order to give resistance to the flow of hydraulic oil toward the rod chamber R1 in the passage 22b, the pressure in the rod chamber R1 is reduced. As a result, the upward movement of the hollow rod 3 is suppressed. Therefore, the shock absorber D exhibits a damping force that suppresses the movement of the hollow rod 3 with respect to the cylinder 1 in the vertical movement.

  Subsequently, when the hollow rod 3 is not displaced with respect to the cylinder 1 and only the rod 2 moves downward with respect to the cylinder 1, the inside of the piston chamber R <b> 2 is compressed as the rod 2 enters the cylinder 1. The hydraulic oil moves to the rod chamber R1 through the passage 22b provided in the piston 4 and becomes excessive from the piston chamber R2 as the volume of the cylinder 1 decreases due to the rod 22 entering the cylinder 1. Oil flows out to the reservoir R through the passage 15b. In order to give resistance to the flow of the hydraulic oil by the passage 22b and the leaf valve 37, a difference occurs between the pressures of the rod chamber R1 and the piston chamber R2, and the differential pressure acts on the piston 4 to cause the rod 22 to move downward. Movement is suppressed.

  Further, when the hollow rod 3 is not displaced with respect to the cylinder 1 and only the rod 2 moves upward with respect to the cylinder 1, the rod chamber R1 is compressed, so that the hydraulic oil is pistoned from the rod chamber R1 through the passage 22a. As the rod 2 moves to the chamber R2 and the rod 2 moves out of the cylinder 1, the volume of the rod 2 increases in the cylinder 1 and the hydraulic oil becomes insufficient. Therefore, the insufficient hydraulic oil passes through the passage 15a into the piston chamber R2. Via the reservoir R. Since the check valve 36 is opened in the piston chamber R2, the pressure is maintained at the same pressure as that of the reservoir R. However, in order to give resistance to the flow of hydraulic oil toward the piston chamber R2 through the passage 22a, the differential pressure is applied to the rod chamber R1 and the piston chamber R2. Occurs, the differential pressure acts on the piston 4 and the upward movement of the rod 2 is suppressed.

  That is, when the hollow rod 3 is not displaced with respect to the cylinder 1 and only the rod 1 is displaced with respect to the cylinder 1, the hollow rod 3 does not affect the increase or decrease in the volume in the cylinder 1. The same operation as a shock absorber having only an output shaft is exhibited, and a damping force that suppresses the movement of the rod 2 relative to the cylinder 1 is exhibited. That is, the shock absorber D generates a damping force that suppresses the displacement of the rod 2 and the hollow rod 3 with respect to the cylinder 1.

  Further, when the rod 2 and the hollow rod 3 operate in synchronism with each other, the rod 2 and the hollow rod 3 do not move relative to each other, so that it is the same as a shock absorber having only a single known output shaft. As a result, the damping force that suppresses the movement of the rod 2 and the hollow rod 3 with respect to the cylinder 1 is exhibited.

  Further, when the rod 2 and the hollow rod 3 operate in opposite phases, one of the rod 2 and the hollow rod 3 operates to enter the cylinder 1, but the other of the rod 2 and the hollow rod 3 is the cylinder 1. Since the operation of retreating from the inside is exhibited, the hydraulic oil of the volume difference that advances and retreats into the cylinder 1 of the rod 2 and the hollow rod 3 is supplied and discharged from the reservoir R to the cylinder 1. A damping force that suppresses each movement is generated.

  That is, the shock absorber D exhibits a damping force with respect to the movement of the rod 2 with respect to the cylinder 1, so that the rod 2 and the cylinder 1 function as a single shock absorber and the movement of the hollow rod 3 with respect to the cylinder 1. Since it also exhibits a damping force, the hollow rod 3 and the cylinder 1 function as another shock absorber separately, so that they function as two shock absorbers arranged in parallel.

  As described above, the shock absorber D in the present embodiment is, as it is, an apparatus in which two parallel shock absorbers are integrated by sharing one cylinder 1 and function as two parallel shock absorbers. The whole is small.

  Furthermore, in this shock absorber D, it is necessary to secure a large reservoir volume because of the configuration in which the two shock absorbers are integrated so that the hollow rod 3 and the rod 2 enter and leave the cylinder 1. Is formed longer than the cylinder 1, and is formed by the rod guide 7, the cylinder member 9, the rod chamber side annular member 8, and the outer cylinder 6 as well as the annular gap 5 between the outer cylinder 6 and the cylinder 1. Since the space 10 also contributes to the volume of the reservoir R, a sufficient reservoir volume can be secured without increasing the size of the outer cylinder 6 in the radial direction, and the shock absorber D can be further downsized. It becomes possible.

  For example, if the rod 2 of the shock absorber D is connected to the actuator, the hollow rod 3 is connected to the vehicle body, and the cylinder 1 is connected to the axle, the shock absorber composed of the rod 2 and the cylinder 1 can generate high-frequency vibrations. Absorption and direct input of high-frequency vibrations to the actuator can be avoided, and a shock absorber composed of the hollow rod 3 and the cylinder 1 is arranged in parallel with the actuator and interposed between the vehicle body and the axle so that the vehicle body vibration Can be attenuated. Conventionally, it has been difficult to install in a narrow space between the vehicle body and the axle, because two independent shock absorbers must be provided to avoid the input of high frequency vibration to the actuator and to reduce the vibration of the vehicle body. In order to use the electric actuator, it is necessary to take measures against vibrations of the motor, and the manufacturing cost is high. However, the shock absorber D of the present invention functions as two shock absorbers in parallel with each other. It can be mounted without difficulty in a narrow space between the axle and an electric actuator using an inexpensive motor can be used for vehicle height adjustment.

  The cylinder 1 accommodates the rod chamber side annular member 8, the piston chamber side annular member 12, the piston 4, the rod 2, the hollow rod 3 and the coil springs 34 and 35, and the cushions 31, 32, 38 and 39. In this state, the cylinder 1 is integrated with the cylinder 1 to form one cylinder assembly C, and the cylinder assembly C is accommodated in the outer cylinder 6. It is easy and the manufacturing efficiency of the shock absorber D is improved.

  Further, in the shock absorber D of this embodiment, the rod 2 is supported by the hollow rod 3 supported by the rod guide 7 and is also supported by two points by being guided by the piston 4 slidably contacting the cylinder 1. As a result, even when lateral force is input, the shaft is prevented from shaking and smooth movement in the axial direction is ensured, and the hollow rod 3 is also supported by the rod guide 7 and slidably contacted with the cylinder 1. Since it is guided by the connected rod 2 and supported at two points, as in the rod 2, the shaft shake is suppressed even when a lateral force is input, and smooth axial movement is ensured.

  Even if the piston 4 is provided on the outer periphery of the hollow rod 3 instead of the rod 2, a damping force can be exerted against the axial movement of the rod 2 and the hollow rod 3 relative to the cylinder 1, so that Also good. In this case, since the rod 2 is not supported by the piston 4, when it is considered that the rod 2 is supported at two locations between the hollow rod 3 and the rod 2, the rod 2 can be used in addition to being supported by the bush 20 at the lower end of the hollow rod 3. In this case, for example, a bush that is slidably contacted with the inner periphery of the hollow rod 3 is attached around the middle of the rod 2 or the rod 2 is longer than the hollow rod 3 even if the hollow rod 3 makes a full stroke upward. If the upper end of 2 is not reached, a bush slidably contacting the outer periphery of the rod 2 may be provided on the inner periphery of the upper end of the hollow rod 3.

  When the piston 4 is provided on the side of the hollow rod 3 as described above, the rod 2 is supported at two points. However, when the piston 4 is connected to the rod 2, the bush 16, 20 and the sliding contact body 23 are all immersed in the liquid in the cylinder 1 and can be lubricated with the liquid in the cylinder 1. The bushes 16 and 20 and the sliding contact body 23 can be lubricated, and the rod 2 and the hollow rod 3 can be lubricated. There is an advantage that smooth movement is guaranteed.

  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.

The present invention is applicable to a shock absorber such as a vehicle suspension.

DESCRIPTION OF SYMBOLS 1 Cylinder 1a Rod chamber side end 1b in cylinder Piston chamber side end 2 in cylinder 2 Rod 2b Screw part 2a in rod Small diameter part 3 in rod 3 Hollow rod 3a Flange 4 Piston 5 Annular gap 6 Outer cylinder 6a Rod chamber side in outer cylinder End 7 Rod guide 8 Rod chamber side annular member 8a Tube portion 8b in rod chamber side annular member Spring receiving portion 9 in rod chamber side annular member Cylindrical member 10 Space 11 Cap 12 Piston chamber side annular members 13, 18 Seal case 13a Seal case Cylinder portion 13b flange portion 13c in seal case holding portion 15 in seal case partition member 15a, 15b passage 16 and 20 in partition member bush 17, 19 seal member 21 collar 22 valve disc 22a and 22b passage in valve disc 23 sliding contact body 23a plate 23b in sliding contact body holding portion 23c in sliding contact body cylindrical portion 23d in sliding contact body sliding contact ring 23e in sliding contact body through hole 23f in plate holding portion 23g annular groove 23h in holding portion Ring groove 24, 26, 36 between sliding contacts Check valve 25, 27 Spring 28 Snap ring 29 Stopper 30 Piston nut 31, 32, 38, 39 Cushion 33 Piston ring 34, 35 Coil spring 37 Leaf valve C Cylinder assembly D Buffer R Reservoir R1 Rod chamber R2 Piston chamber

Claims (2)

A cylinder, a rod that is movably inserted into the cylinder, a hollow rod that is movably inserted into the cylinder and is movably mounted on the outer periphery of the rod, and a rod or an outer periphery of the hollow rod. And a piston that is slidably inserted into the cylinder and divides the rod chamber and the piston chamber in the cylinder, and a rod chamber-side annular member that is fixed to the rod chamber-side end of the cylinder and has a hollow rod inserted therethrough And a cylinder assembly integrated with a piston chamber side annular member fixed to the piston chamber side end of the cylinder, and accommodated in an outer cylinder that forms a reservoir between the cylinder assembly and the cylinder assembly vessel. A rod side spring housed in the rod chamber and interposed between the rod chamber side annular member and the piston, and a piston side spring housed in the piston chamber and interposed between the piston chamber side annular member and the piston The shock absorber according to claim 1, further comprising: positioning the piston to a neutral position.

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