JP2019060452A - damper - Google Patents

Abstract

To provide a damper which enables easy optimization of characteristics of an accumulator and enables easy installation operation.SOLUTION: A damper D of the invention includes: a cylinder 1; a piston 2 which is slidably inserted into the cylinder 1 and partitions the interior of the cylinder 1 into an extension side chamber R1 and a pressure side chamber R2; a rod 3 which is inserted into the cylinder 1 and connected to the piston 2; an external cylinder 4 which is disposed at the outer periphery side of the cylinder 1 and covers the cylinder 1; and an accumulator A installed between the cylinder 1 and the external cylinder 4. The accumulator A has: a housing 10 provided with one or more holes 10a; free pistons 11, each of which is slidably inserted into the hole 10a; and spring elements 12, each of which biases the free piston 11 to the liquid chamber side.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a damper.

  The damper is widely used to suppress the vibration of a vibration control target such as a machine, a structure or a vehicle. The damper includes, for example, a cylinder, a piston slidably inserted into the cylinder to divide the inside of the cylinder into an expansion side chamber and a compression side chamber, and a rod inserted into the cylinder and connected to the piston. During expansion and contraction, a pressure difference is generated between the expansion side chamber and the compression side chamber to exhibit a damping force that resists expansion and contraction.

  Usually, in the case of a single rod type, the damper compensates for the volume change when the rod moves in and out of the cylinder if it is a single rod type and the volume change due to the temperature change of the working fluid. In order to compensate for the volume change, a reservoir for storing the gas and the working fluid is provided.

  In order for such a damper to exert the set damping force regardless of the mounting posture to the object to be damped, it is necessary to prevent the gas in the reservoir from mixing into the cylinder, in which case the reservoir is The accumulator is preferably configured to be separated so as to mix with the working fluid.

  For example, although there is a damper in which the accumulator is formed in the rod, when there is no space in the installation space, the outer diameter of the damper is limited and the rod must be reduced in diameter, which may make it impossible to secure the capacity of the accumulator ( For example, refer to Patent Document 1).

  On the other hand, there is a damper in which an outer cylinder is provided on the outer periphery of a cylinder and an annular gap between the cylinder and the outer cylinder is used as an accumulator (see, for example, Patent Document 2).

Unexamined-Japanese-Patent No. 2004-116552 Japanese Patent Application Laid-Open No. 11-82605

  By the way, when the damper is most extended, it is necessary to take care so that the pressure in the cylinder does not fall below atmospheric pressure, and when the damper is fully contracted, the pressure in the cylinder pushes the rod out of the cylinder (rod Care must be taken so that the reaction force does not become excessive. In order to satisfy such a requirement, in a damper provided with an accumulator, the accumulator may apply a preload to the expansion side chamber and the pressure side chamber in the cylinder.

  However, the length and thickness of the cylinder and the outer cylinder are uniquely determined in design depending on the installation space and the object to be damped. As described above, if it is attempted to use the space between the cylinder and the outer cylinder as an accumulator, the volume of the accumulator is uniquely determined in the design, and therefore, the rod reaction force even if the damper is maximally contracted It is very difficult to adjust the characteristics of the accumulator so that is optimal.

  In order to solve this problem by adopting a structure in which a separate accumulator is provided on the outside of the damper, the whole damper becomes large in size, and the damper is asymmetric because it has an asymmetric shape. The installation work becomes very troublesome without any interference with parts.

  Therefore, an object of the present invention is to provide a damper that is easy to optimize the characteristics of the accumulator and easy to install.

  In order to achieve the above object, the damper of the present invention comprises: a cylinder; a piston slidably inserted in the cylinder to divide the cylinder into an expansion side chamber and a compression side chamber; A housing provided with a rod to be connected, an outer cylinder disposed on the outer peripheral side of the cylinder and covering the cylinder, and an accumulator installed between the cylinder and the outer cylinder, the accumulator being provided with one or more holes A free piston slidably inserted in the hole; and a spring element biasing the free piston toward the fluid chamber.

  Further, another damper according to the present invention includes a cylindrical accumulator, a piston slidably inserted in the accumulator to divide the accumulator into an expansion side chamber and a pressure side chamber, and is inserted into the accumulator and connected to the piston. A cylindrical housing having at least one hole provided with an accumulator, a free piston slidably inserted in the hole, and a spring for biasing the free piston toward the liquid chamber And an element.

  Furthermore, another damper of the present invention includes a cylinder, a piston slidably inserted in the cylinder to divide the cylinder into an expansion side chamber and a pressure side chamber, a rod inserted into the cylinder and connected to the piston A housing provided with a cylindrical accumulator disposed on the outer periphery of the cylinder and covering the outer periphery of the cylinder, the accumulator being provided with one or more holes, a free piston slidably inserted in the holes, and a free And a spring element for biasing the piston toward the fluid chamber.

  According to the damper configured as described above, the accumulator volume of the accumulator can be adjusted so that the rod reaction force becomes appropriate from the maximum extension to the maximum contraction of the damper, and the characteristics of the accumulator can be tuned to be optimum for the damper. In addition, it is possible to avoid the enlargement of the damper and the asymmetrical shape.

  Further, the housing in the accumulator may have a straightening passage leading from one end to the other end, and according to the damper configured in this way, the working fluid reduces the flow velocity when passing through the straightening passage, and the working fluid is in the working fluid Since the generation of air bubbles can be prevented, the damping force as set at all times can be exhibited.

  Furthermore, the damper may be configured by arranging a plurality of accumulators in an axial direction between the cylinder and the outer cylinder. According to the damper configured as described above, it is possible to secure the volume of the accumulator while shortening the axial dimension of the housing in each accumulator, and it becomes very easy to process each accumulator.

  Furthermore, the housing of the accumulator may have a damping passage communicating the fluid chamber with the cylinder or the accumulator, and a damping valve for resisting the flow of liquid passing through the damping passage. According to the damper configured as described above, the number of parts can be reduced by the structure of the damper, or the length in the longitudinal direction of the damper can be shortened.

  According to the damper of the present invention, optimization of the characteristics of the accumulator is easy, and installation work is also easy.

It is sectional drawing of the damper in 1st embodiment. It is a top view of the accumulator in the damper of a first embodiment. It is sectional drawing of the damper in the 1st modification of 1st embodiment. It is sectional drawing of the damper in the 2nd modification of 1st embodiment. It is sectional drawing of the damper in the 3rd modification of 1st embodiment. It is sectional drawing of the damper in the 4th modification of 1st embodiment. It is sectional drawing of the damper in the 5th modification of 1st embodiment. It is sectional drawing of the damper in the 6th modification of 1st embodiment. It is sectional drawing of the damper in 2nd embodiment. It is sectional drawing of the damper in the 1st modification of 2nd embodiment. It is sectional drawing of the damper in 3rd embodiment.

  Hereinafter, the present invention will be described based on the embodiments shown in the drawings. In addition, the same reference numerals are given to the configurations common to the dampers of the respective embodiments described below, and in order to avoid the duplication of the description, the other configurations are implemented for the configuration described in the description of the damper of one embodiment. The detailed description is omitted in the description of the damper in the form of.

First Embodiment
The damper D1 in the first embodiment is, as shown in FIG. 1, a cylinder 1 and a piston 2 slidably inserted in the cylinder 1 to divide the inside of the cylinder 1 into an expansion chamber R1 and a compression chamber R2. A rod 3 inserted into the cylinder 1 and coupled to the piston 2, an outer cylinder 4 disposed on the outer peripheral side of the cylinder 1 to cover the cylinder 1, and an accumulator installed between the cylinder 1 and the outer cylinder 4 A is configured.

  Hereinafter, each part of the damper D1 will be described in detail. The valve case 5 is fitted to one end of the cylinder 1 and the rod guide 6 is fitted to the other end. Further, on the outside of the cylinder 1 is provided an outer cylinder 4 which covers the outer periphery of the cylinder 1 and forms an annular gap S communicated with the inside of the cylinder 1 with the cylinder 1. One end of the outer cylinder 4 is closed by the cap 7, and the other end of the outer cylinder 4 is closed by the rod guide 6. The cylinder 1 is held by a rod guide 6 mounted on the outer cylinder 4 and a valve case 5 in contact with the cap 7 and is fixed while being accommodated in the outer cylinder 4.

  The piston 2 is slidably inserted in the cylinder 1 and divides the inside of the cylinder 1 into an expansion chamber R1 and a compression chamber R2. Each of the expansion side chamber R1 and the pressure side chamber R2 is filled with a hydraulic fluid as a hydraulic fluid. In addition, although a working fluid is used as working oil in this example, you may be used as other liquids, such as water and aqueous solution.

  The piston 2 is provided with an extension side passage 2a and a pressure side passage 2b that communicate the extension side chamber R1 with the pressure side chamber R2. The expansion-side passage 2a is provided with an expansion-side damping valve 2c that allows only the flow of hydraulic fluid from the expansion-side chamber R1 to the pressure-side chamber R2 and provides resistance to this flow, and the pressure-side passage 2b includes A pressure-side damping valve 2d is provided which allows only the flow of hydraulic oil toward the expansion side chamber R1 and which resists the flow. In addition, various damping valves, such as a pressure regulation valve and a relief valve, can be used for expansion side damping valve 2c and pressure side damping valve 2d. As described above, in the present embodiment, although both the extension side passage 2a and the pressure side passage 2b are set as one-way passages, instead of the extension side passage 2a and the pressure side passage 2b, the extension side chamber R1 communicates with the pressure side chamber R2. A passage may be provided to allow bidirectional flow, and a damping valve may be provided in this passage to allow bidirectional flow such as a throttle.

  Further, one end of the rod 3 is movably inserted into the cylinder 1 through the inside of the rod guide 6 and is connected to the piston 2, and the other end protrudes outside the cylinder 1. In this example, the damper D1 is a so-called single rod type damper in which the rod 3 is inserted only into the expansion chamber R1. However, the damper D1 is also inserted into the pressure chamber R2 and both ends of the rod 3 are both ends of the cylinder 1 It may be a so-called double rod type damper which protrudes outward from each other. The damper D1 is provided with brackets 3a and 7a on both of the cap 7 and the other end of the rod 3 so as to be able to be connected to the vibration control target.

  The valve case 5 includes a discharge passage 5a and a suction passage 5b that communicate the pressure side chamber R2 with the annular gap S. The discharge passage 5a is provided with a base valve 5c that resists the flow of hydraulic fluid from the pressure side chamber R2 toward the annular gap S, and the suction passage 5b includes hydraulic fluid from the annular gap S toward the pressure side chamber R2. There is provided a check valve 5d which allows only flow. As the base valve 5c, damping valves of various structures can be used in the same manner as the expansion damping valve 2c and the compression damping valve 2d. The base valve 5c may allow only the flow of fluid from the pressure side chamber R2 to the annular gap S, or may allow bi-directional flow.

  As shown in FIGS. 1 and 2, the accumulator A energizes a cylindrical housing 10 having a plurality of holes 10a, a free piston 11 slidably inserted into the holes 10a, and a free piston 11 And a coil spring 12 as a spring element.

  The housing 10 has a thick cylindrical shape and is sandwiched by C rings 13 and 14 mounted on the inner periphery of the outer cylinder 4 so that the axial movement is restricted. It is accommodated in the annular clearance S between. The C rings 13 and 14 may be mounted on the outer periphery of the cylinder 1. Further, in the present embodiment, as shown in FIG. 2, the housing 10 is provided with six holes 10a formed along the axial direction, and is provided with two rectification passages 10b opened from one end and connected to the other end. There is.

  The diameter of the flow straightening passage 10b is set smaller than the diameter of the hole 10a. Further, in this example, the hole 10a is a through hole which penetrates the housing 10 in the axial direction, and the head end which is the left end in FIG. 1 is opened, while the bottom end which is the right end in FIG. It is closed by a plug 15 attached to the bottom end of 10a. The volume of the hole 10a contributes to the accumulator volume in the accumulator A, and the number and the volume of the holes 10a may be set to be suitable for the damper D1. In addition, the plug 15 may be eliminated and the hole 10a may be a blind hole having a bottom. The housing 10 may be formed of metal but may be formed of synthetic resin. When the housing 10 is molded with a synthetic resin, since manufacturing using a mold such as injection molding can be performed, no drilling process is required, and the number of processing steps can be reduced.

  The free piston 11 is slidably inserted into the hole 10a. The free piston 11 divides the inside of the hole 10a into a liquid chamber L communicated with the pressure side chamber R2 in the cylinder 1 through the annular gap S and the discharge passage 5a or the suction passage 5b and a sealed chamber C sealed. There is. The fluid chamber L and the annular gap S are filled with the working fluid as the working fluid, similarly to the expansion side chamber R1 and the pressure side chamber R2.

  In the closed chamber C, a gas is filled and a coil spring 12 is accommodated. The gas may be an inert gas such as nitrogen, but the use of other gases such as the atmosphere is also possible. One end of the coil spring 12 is fitted with a protrusion 11 a provided at the end of the free piston 11, and the other end of the coil spring 12 is fitted with a protrusion 15 a provided at the end of the plug 15. Thus, the free piston 11 is prevented from falling out of the hole 10 a of the housing 10 by the coil spring 12 and the plug 15 so as not to be pulled outward. The free piston 11 is biased toward the liquid chamber L by the pressure in the closed chamber C and the elastic force of the coil spring 12, and pressurizes the annular gap S and the cylinder 1. The spring element may be an elastic body such as a spring of a coil spring 12 or rubber, or may be an air spring configured by enclosing a gas in the closed chamber C.

  The operation of the damper D1 configured as described above will be described. First, an operation in the case where the damper D1 is operated to extend will be described. When the damper D1 operates to extend and the piston 2 moves to the left in FIG. 1 with respect to the cylinder 1, the expansion side chamber R1 is compressed and the volume of the pressure side chamber R2 is expanded. Then, the hydraulic oil in the expansion side chamber R1 to be compressed passes through the expansion side passage 2a and moves to the pressure side chamber R2. In addition, although the amount of hydraulic oil for which the rod 3 is withdrawn from the cylinder 1 runs short in the cylinder 1, the free piston 11 moves to the liquid chamber L side, and the hydraulic oil corresponding to the shortage is pushed out from the liquid chamber L The pressure is supplied into the cylinder 1 via the suction passage 5b. As described above, the hydraulic fluid for the volume of the rod 3 exiting from the cylinder 1 is supplied into the cylinder 1 by the accumulator A, and the volume compensation during the extension stroke of the damper D1 is performed. Then, the expansion damping valve 2c resists the flow of the hydraulic oil from the expansion chamber R1 to the compression chamber R2 through the expansion passage 2a, so that the pressure in the expansion chamber R1 rises. The pressure in the pressure side chamber R2 that receives the supply of hydraulic oil from the other accumulator A becomes equal to the pressure in the accumulator A. Therefore, a difference occurs between the pressure of the expansion side chamber R1 and the pressure side chamber R2, and the damper D1 exerts an expansion side damping force in the direction that prevents the expansion corresponding to the pressure difference.

  Subsequently, an operation when the damper D1 is contracted will be described. When the damper D1 is contracted to move the piston 2 relative to the cylinder 1 to the right in FIG. 1 with respect to the cylinder 1, the pressure side chamber R2 is compressed and the volume of the expansion side chamber R1 is enlarged. Then, the hydraulic oil in the pressure side chamber R2 to be compressed passes through the pressure side passage 2b and moves to the expansion side chamber R1. Further, the volume of hydraulic oil for which the rod 3 enters the cylinder 1 is excessive in the cylinder 1. The excess hydraulic oil is discharged to the annular gap S through the discharge passage 5a, and the free piston 11 moves in the hole 10a in the direction to compress the sealed chamber C to enlarge the liquid chamber L, and the accumulator A is used. Absorbed As described above, the hydraulic oil for the volume in which the rod 3 enters the cylinder 1 is absorbed by the accumulator A, and the volume compensation at the contraction stroke of the damper D1 is performed. Then, the base valve 5c gives resistance to the flow for operation from the pressure side chamber R2 to the accumulator A through the discharge passage 5a, and the flow of hydraulic oil from the pressure side chamber R2 to the expansion side chamber R1 through the pressure side passage 2b. Against the expansion damping valve 2c provides resistance. Therefore, as the pressure in the pressure side chamber R2 rises, the pressure in the expansion side chamber R1 drops and a difference occurs between the pressure in the expansion side chamber R1 and the pressure side chamber R2, and the damper D1 prevents the contraction corresponding to the pressure difference. Demonstrate pressure side damping force. The accumulator A can displace the free piston 11 to expand / contract the liquid chamber L and absorb the volume change of the working oil when the volume change due to the temperature change of the working oil occurs.

  As mentioned above, the damper D1 exerts a damping force by the base valve 5c provided in the discharge passage 5a, the expansion side damping valve 2c and the pressure side damping valve 2d provided in the piston 2. Alternatively, the cylinder 1 may be provided with an orifice communicating with the fluid chamber L via the annular gap S to exert a damping force. In this case, if the orifices are arranged in a plurality of axial directions, the damper D1 moves the expansion side chamber R1 or the pressure side chamber R2 as the liquid chamber L as the piston 2 is displaced from the center of the cylinder 1 toward the stroke end. Since the number of orifices communicating with the valve D changes, the damper D1 can exert a damping force that changes depending on the position of the piston 2. The addition of such an orifice can also be employed for the dampers of the embodiments described below.

  During the contraction stroke of the damper D1, the hydraulic fluid flows from the cylinder 1 toward the fluid chamber L of the accumulator A, but when the contraction speed is high, the hydraulic fluid passing through the discharge passage 5a vigorously flows into the annular gap S. However, the liquid chamber L of the accumulator A is opened to the left in FIG. 1 on the head side of the damper D1, and the hydraulic oil passes through the small diameter passage 10b provided in the housing 10 to the liquid chamber L. To reach. The flow velocity of the hydraulic oil is decelerated by the passage of the straightening passage 10 b before reaching the fluid chamber L.

  Therefore, when the flow straightening passage 10b is provided as described above, the flow velocity of the hydraulic fluid is reduced to suppress the stirring of the hydraulic fluid in the annular gap S, and the gas dissolved in the hydraulic fluid appears as bubbles. You can prevent When air bubbles appear in the hydraulic oil, the damper D1 hardly exerts the set damping force. However, in the damper D1 of this example, the generation of the air bubbles can be prevented, so that the set damping force can always be exhibited.

  Although the straightening passage 10b is formed so as to penetrate the meat of the housing 10 in the axial direction in this example, a groove may be provided on the outer periphery or the inner periphery of the housing 10 to be a straightening passage for reducing the flow velocity. Further, like the damper D11 of the first modified example of the first embodiment shown in FIG. 3, the inner diameter of the housing 10 is set between the cylinder 1 and the outer diameter of the housing 10 such that the outer diameter can be fitted to the outer cylinder 4 The gap between the housing 10 and the cylinder 1 may be used as a flow straightening passage for reducing the flow velocity, as a diameter capable of forming a gap capable of reducing the flow velocity. Furthermore, like the damper D12 of the second modified example of the first embodiment shown in FIG. 4, with the inside diameter of the housing 10 being a diameter that can be fitted to the cylinder 1, the outside diameter of the housing 10 is The gap between the housing 10 and the outer cylinder 4 may be used as a flow straightening passage for reducing the flow velocity as a diameter capable of forming a gap capable of reducing the flow velocity therebetween. In this case, the accumulator A may be fixed to the cylinder 1 using C rings 13 and 14 mounted on the outer periphery of the cylinder 1. In addition, when it is not necessary to reduce the flow velocity, the accumulator A may be disposed such that the opening of the liquid chamber L faces the bottom side of the damper D1.

  And, in the damper D1 of the present invention, the annular gap S between the cylinder 1 and the outer cylinder 4 is not used as it is as an accumulator, but the annular gap S is provided with one or more holes 10a. The accumulator A is provided with a housing 10, a free piston 11 for dividing the liquid chamber L into the hole 10a, and a coil spring (spring element) 12.

  Since the volume of the holes 10a contributing to the accumulator volume of the accumulator A and the number of installed holes can be set arbitrarily as far as the housing 10 permits, according to the damper D1 provided with the accumulator A, the rod anti The accumulator volume of the accumulator A can be adjusted so that the force is appropriate, and the characteristics of the accumulator A can be tuned to be optimal for the damper D1. In addition, since the accumulator A is accommodated in the annular gap S between the cylinder 1 and the outer cylinder 4, it is possible to prevent the damper D1 from becoming large and having an asymmetrical shape, and when attaching the damper D1 to the installation space There is no need to cause interference with other parts. As mentioned above, according to the damper D1 of this invention, optimization of the characteristic of the accumulator A is easy, and installation operation also becomes easy. When tuning the characteristics of the accumulator A, the number and the volume of the holes 10a provided in the housing 10 may be changed according to the specifications of the damper D1, but the number and the volume of the holes 10a are determined The characteristics of the accumulator A may be tuned by providing the free piston 11 and the spring element only in the number of holes 10a that is optimum for the damper D1 according to the required accumulator volume.

  In this example, since the accumulator A is accommodated in the annular gap S between the cylinder 1 and the outer cylinder 4, the shape of the housing 10 viewed in the axial direction is not limited to a circle, but may be a sector or a C. May be

  Further, in the present embodiment, the valve case 5 is provided, but the valve case 5 is eliminated and the damper D13 of the third modification of the first embodiment shown in FIG. A through hole 1a communicating with the annular gap S is provided at the right end, and a damping passage 16 and a suction passage 17 leading from one end of the housing 10 to the other end of the housing 10 in the accumulator A and a damping valve 18 provided in the damping passage 16 And a check valve 19 provided in the suction passage 17. In this case, the housing 10 does not include the rectifying passage 10b.

  The bottom side on the right of the accumulator A in the annular gap S in FIG. 5 is communicated with the inside of the cylinder 1 by the through hole 1a and functions as a part of the pressure side chamber R2. The damping valve 18 resists the flow of hydraulic fluid from the pressure side chamber R2 to the fluid chamber L in the accumulator A. The check valve 19 allows only the flow of hydraulic oil from the liquid chamber L to the pressure side chamber R2 in the accumulator A. Therefore, when the damper D13 extends, the hydraulic oil for the volume by which the check valve 19 opens and the rod 3 exits from the fluid chamber L is supplied to the pressure side chamber R2 to perform volume compensation, and the damper D13 The expansion side damping force corresponding to the pressure difference between the expansion side chamber R1 and the compression side chamber R2 generated by the expansion side damping valve 2c is exerted. Further, when the damper D1 is contracted, hydraulic oil of a volume in which the rod 3 enters the cylinder 1 passes from the pressure side chamber R2 through the damping valve 18 and moves to the liquid chamber L to perform volume compensation. D13 exerts a pressure side damping force corresponding to the pressure difference between the pressure side chamber R2 and the expansion side chamber R1 generated by the pressure side damping valve 2d and the damping valve 18.

  Thus, in the damper D13 of the third modified example of the first embodiment, the bottom side of the right side of the accumulator A in FIG. 5 functions as a part of the pressure side chamber R2, and the damping valve 18 functions as a base valve. Therefore, the accumulator A functions as the valve case 5. The function of the valve case 5 is to form the discharge passage 5a and the suction passage 5b that divide the accumulator and the pressure side chamber R2 and communicate the accumulator A and the pressure side chamber R2, and hold the base valve 5c and the check valve 5d. , This function can be integrated into accumulator A. Therefore, since the number of parts of the damper D13 can be reduced, the damper D13 becomes inexpensive.

  As in the damper D14 of the fourth modification of the first embodiment shown in FIG. 6, a plurality of accumulators A are axially arranged in the annular gap S between the cylinder 1 and the outer cylinder 4 May be In this case, even if the accumulators A are arranged side by side, a notch 10c is provided on the outer periphery of the head side end which is the left end in FIG. 3 of the housing 10 so that the openings of the holes 10a and 10b are not blocked by the adjacent accumulators A. ing. Thus, the open end of the hole 10a and the straightening passage 10b face the notch 10c. Then, if the housings 10 of the respective accumulators A are arranged in the same direction, the end of the housing 10 not provided with the notch 10c is in contact with the end of the housing 10 provided with the notch 10c. It is possible to prevent the open end and the straightening passage 10b from being blocked.

  When the damper D14 is long, the housing 10 may become long when securing the accumulator volume with one accumulator A and processing may become difficult. However, when installing a plurality of accumulators A While making it possible to secure the accumulator volume while shortening the axial dimension of the housing 10 in the accumulator A, the processing of each accumulator A becomes very easy.

  In addition, although the accumulator A is applied to the biflow type damper D1 as described above, the uniflow type damper D15 is used as the damper D15 of the fifth modification example of the first embodiment shown in FIG. 7. An accumulator A may be applied.

  Specifically, in damper D15, check valve 2f is set in piston passage 2e and piston passage 2e in a one-way passage which permits only the flow of hydraulic fluid from pressure side chamber R2 to extension side chamber R1. Provided in the valve case 5, the discharge passage 5a and the base valve 5c are eliminated and only the suction passage 5b and the check valve 5d are provided, and the rod guide 6 communicates with the expansion side chamber R1 and the annular gap S A damping valve 21 is provided which allows only the flow of hydraulic fluid passing through the passage 20 from the expansion side chamber R1 to the annular gap S and provides resistance to this flow. The accumulator A is accommodated in the annular gap S in the same manner as the damper D1. In this example, the accumulator A is fixed by the C rings 13 and 14 with the opening of the liquid chamber L directed to the bottom side on the right side in FIG. ing.

  When the damper D15 configured as described above is operated to extend, hydraulic oil is discharged from the expansion side chamber R1 compressed by the piston 2 into the annular gap S via the damping passage 20. In addition, hydraulic oil of a volume in which the rod 3 exits from the inside of the cylinder 1 is supplied from the liquid chamber L to the pressure side chamber R2 which is expanded through the suction passage 5b. Then, the damping valve 21 resists the flow of hydraulic fluid from the expansion side chamber R1 toward the annular gap S, so the pressure in the expansion side chamber R1 rises, and the pressure in the pressure side chamber R2 is equal to the pressure in the accumulator A. Become. Therefore, when the damper D15 operates to extend, a pressure difference is generated between the expansion side chamber R1 and the pressure side chamber R2 by the damping valve 21, and the damper D15 exerts an expansion side damping force corresponding to the pressure difference to prevent the expansion operation.

  Further, when the damper D15 is contracted, the hydraulic oil moves from the pressure side chamber R2 compressed by the piston 2 to the expansion side chamber R1 via the piston passage 2e. Further, since the volume of hydraulic oil in which the rod 3 enters the cylinder 1 is excessive in the cylinder 1, the excess hydraulic oil is discharged into the annular gap S through the damping passage 20. The excess hydraulic oil passes through the annular gap S and passes through the straightening passage 10b to reduce the flow velocity, and the free piston 11 retracts toward the sealed chamber C in the hole 10a to expand the liquid chamber L Absorption and volume compensation during contraction operation. Then, the damping valve 21 provides resistance to the flow of the hydraulic oil from the expansion side chamber R1 toward the annular gap S, and the check valve 2f is opened so that the expansion side chamber R1 and the pressure side chamber R2 communicate with each other in the piston passage 2e. Since the pressure is generated, the pressures of the expansion side chamber R1 and the pressure side chamber R2 rise equally. Since the area of the piston 2 facing the expansion side chamber R1 is smaller than the area of the piston 2 facing the pressure side chamber R2 by the cross sectional area of the rod 3, the piston 2 is pushed leftward in FIG. Thus, the damper D15 exerts a pressure side damping force that hinders the contraction operation.

  As described above, in the damper D15, the hydraulic oil is always discharged from the expansion side chamber R1 to the annular gap S via the damping passage 20 when the expansion and contraction operation is performed, and the hydraulic oil is one-way circulating in the order of the accumulator A, pressure side chamber R2 and expansion side chamber R1. Is a uniflow type damper. Even with the damper D15 configured as described above, the damping force in the direction that hinders expansion and contraction can be exhibited at the time of expansion and contraction operation, and volume compensation is performed by the accumulator A. Therefore, even in the uniflow type damper D15 provided with the accumulator A, the accumulator volume of the accumulator A can be adjusted so that the rod reaction force is appropriate from the maximum extension to the maximum contraction, and the characteristics of the accumulator A are optimized for the damper D15. Can be tuned to In addition, since the accumulator A is accommodated in the annular gap S between the cylinder 1 and the outer cylinder 4, it is possible to prevent the damper D15 from becoming large and having an asymmetrical shape, and when attaching the damper D15 to the installation space. And avoid causing interference with other parts. As mentioned above, the damper D15 of this example makes optimization of the characteristic of the accumulator A easy, and installation operation also becomes easy.

  As in the damper D16 of the sixth modification of the first embodiment shown in FIG. 8, the damping valve 21 provided in the rod guide 6 may be provided in the accumulator A. In this case, in the rod guide 6, instead of the damping passage 20 and the damping valve 21, only the passage 22 communicating the expansion side chamber R1 with the head side in FIG. 8 from the accumulator A in the annular gap S is provided. The rectifying passage 10b of the housing 10 in the accumulator A may be eliminated, and the damping passage 23 and the damping valve 24 may be provided in the housing 10. In this case, the opening of the liquid chamber L is directed to the bottom side which is the right side in FIG. 8, and the damping valve 21 is the right side in FIG. It is set to allow only the flow of hydraulic oil to the bottom side of. The damper D16 configured in this way functions as a uniflow type damper as the damper D15, but since the damping passage 23 and the damping valve 24 are provided in the accumulator A, it is not necessary to provide the rod guide 6 with the damping valve Thus, the axial length of the rod guide 6 can be shortened. Thus, the longitudinal dimension of the damper D16 set to the uniflow type can be shortened.

Second Embodiment
As shown in FIG. 9, the damper D2 in the second embodiment uses the housing 30 of the accumulator A1 as it is as a cylinder. Specifically, the damper D2 is inserted into the cylindrical accumulator A1, the piston 2 slidably inserted in the accumulator A1 and partitioning the inside of the accumulator A1 between the expansion side chamber R1 and the pressure side chamber R2, and the accumulator A1 And a rod 3 connected to the piston 2.

  The accumulator A1 in this example includes a housing 30 having a plurality of holes 30a, a free piston 31 slidably inserted in the holes 30a, and a coil spring 32 as a spring element for biasing the free piston 31. ing.

  The housing 30 has a cylindrical shape in addition to the hole 30a and the passage 30b, and the piston 2 is slidably inserted in the inner periphery, and an annular shape which is fitted to the rod guide 6 and the cap 7 at both outer peripheral portions. Sockets 30c and 30d. Therefore, in this case, the housing 30 is attached to the rod guide 6 and the cap 7, and functions as a strength member in the damper D2 and also functions as a cylinder. It is divided into R2. Also, in the present example, the housing 30 is provided with six holes 30a formed along the axial direction, as with the housing 10 in the accumulator A of the first embodiment, and is open from one end to the other end It has two flow straightening passages 30b communicating with each other. The diameter of the flow straightening passage 30b is set to be smaller than the diameter of the hole 30a. Further, in the present embodiment, the holes 30a are through holes that penetrate the housing 30 in the axial direction, and are opened to the inside of the sockets 30c and 30d at both ends of the housing 30, respectively. The head end, which is the left end in FIG. 9 of the hole 30a, faces the annular recess 6a provided on the outer periphery of the rod guide 6, and is communicated with the flow straightening passage 30b via the annular recess 6a. Further, the bottom end which is the right end in FIG. 9 is closed by a plug 33 attached to the bottom end of the hole 30a. The bottom end on the right end in FIG. 9 of the flow straightening passage 30b faces the annular recess 5e provided on the outer periphery of the valve case 5, and communicates with the pressure side chamber R2 through the discharge passage 5a and the suction passage 5b. Thus, the fluid chamber L in the accumulator A1 is in communication with the pressure side chamber R2 provided in the housing 30 through the annular recesses 5e and 6a and the straightening passage 30b, but a flow path communicating the fluid chamber L with the pressure side chamber R2. The structure is not limited to this. Further, the volume of the hole 30a contributes to the accumulator volume as well as the hole 10a of the accumulator A, and the number and the volume of the holes 30a may be set to be suitable for the damper D2. In addition, the plug 33 may be eliminated and the hole 30a may be a blind hole having a bottom.

  The free piston 31 is slidably inserted into the hole 30a. The free piston 31 divides the inside of the hole 30a into a liquid chamber L communicated with the pressure side chamber R2 in the cylinder 1 through the discharge passage 5a or the suction passage 5b and a closed chamber C sealed. The fluid chamber L is filled with a hydraulic fluid as a working fluid, similarly to the expansion side chamber R1 and the pressure side chamber R2.

  In the closed chamber C, a gas is filled and a coil spring 32 is accommodated. The gas may be an inert gas such as nitrogen, but the use of other gases such as the atmosphere is also possible. One end of the coil spring 32 is fitted with a protrusion 31 a provided at the end of the free piston 31, and the other end of the coil spring 32 is fitted with a protrusion 33 a provided at the end of the plug 33. Accordingly, the free piston 31 is prevented from falling out of the hole 10 a of the housing 10 by the coil spring 32 and the plug 15 so as not to be pulled outward. The free piston 31 is biased toward the liquid chamber L by the pressure in the closed chamber C and the elastic force of the coil spring 32, and pressurizes the expansion side chamber R1 and the pressure side chamber R2 provided inside the accumulator A. There is. The spring element may be an elastic body such as a spring of a coil spring 32 or rubber, or may be an air spring configured by sealing a gas in the closed chamber C.

  The piston 2 is slidably inserted into the inner periphery of the housing 30, and the space in the accumulator A is partitioned by the piston 2 into an expansion chamber R1 and a compression chamber R2. Further, the piston 2 includes an extension side passage 2a and a pressure side passage 2b for communicating the extension side chamber R1 and the pressure side chamber R2, an extension side damping valve 2c provided in the extension side passage 2a, and a pressure side damping provided in the pressure side passage 2b. A valve 2d is provided.

  That is, the damper D2 differs from the damper D1 in that the cylinder 1 and the outer cylinder 4 are eliminated and the accumulator A1 functions as the cylinder 1, and exhibits the same operation as the damper D1. Thus, even if the damper D2 is configured, the volume and the number of the holes 30a contributing to the accumulator volume of the accumulator A1 can be arbitrarily set as long as the housing 30 permits. Therefore, according to the damper D2 provided with the accumulator A1, the accumulator volume of the accumulator A1 can be adjusted so that the rod reaction force becomes appropriate from the maximum extension to the maximum contraction, and the characteristics of the accumulator A1 are optimized for the damper D2. It can be tuned. Further, the accumulator A1 doubles as the cylinder 1 and can prevent the damper D2 from becoming large and having an asymmetrical shape, and when the damper D2 is attached to the installation space, interference with other parts can be avoided. As mentioned above, according to the damper D2 of this invention, optimization of the characteristic of accumulator A1 is easy, and installation operation also becomes easy. When tuning the characteristics of the accumulator A1, the number and volume of the holes 30a provided in the housing 30 may be changed according to the specifications of the damper D2, but the number and volume of the holes 30a are determined in advance. The characteristics of the accumulator A1 may be tuned by providing the free piston 31 and the spring element only in the number of holes 30a that is optimum for the damper D2 according to the required accumulator volume.

  Further, since the damper D2 of the present example includes the straightening passage 30b in the housing 30, the hydraulic fluid can reduce the flow velocity from the pressure side chamber R2 to the liquid chamber L during the contraction stroke of the damper D2, It is possible to prevent the occurrence and always exert the set damping force.

  Even when the housing 30 of the accumulator A1 is made to function as a cylinder in this manner, a base valve is provided to the accumulator A1 like the damper D13 of the third modification of the first embodiment. Adoption is also possible, and application of accumulator A1 to a damper of uni-flow structure is also possible like damper D15 of the 5th modification of a first embodiment, and damper D16 of a 6th modification.

  Further, like the damper D21 in the first modified example of the second embodiment shown in FIG. 10, the outer cylinder 40 is provided on the outer periphery of the accumulator A1 functioning as a cylinder, and the axial force and other loads are You may receive it.

Third Embodiment
Furthermore, in addition to the structure of the damper D2 of the second embodiment as in the damper D3 of the third embodiment shown in FIG. 11, the cylinder 1 may be provided on the inner periphery of the accumulator A1.

  The damper D3 of the third embodiment is inserted into the cylinder 1, the piston 2 slidably inserted in the cylinder 1 and partitioning the inside of the cylinder 1 into the expansion side chamber R1 and the pressure side chamber R2, and the cylinder 1 And a cylindrical accumulator A1 disposed on the outer periphery of the cylinder 1 and covering the outer periphery of the cylinder 1. Even in the damper D3 configured in this way, the same operation as the damper D2 of the second embodiment is exhibited, and the accumulator volume of the accumulator A1 is set such that the rod reaction force becomes appropriate from the maximum extension to the maximum contraction. The characteristics of the accumulator A1 can be tuned so as to be optimum for the damper D3. In addition, since the accumulator A1 has a cylindrical shape covering the outer periphery of the cylinder 1, it is possible to prevent the damper D3 from becoming large and having an asymmetrical shape, and when the damper D3 is attached to the installation space You do not have to invite me. As mentioned above, according to the damper D3 of this invention, optimization of the characteristic of accumulator A1 is easy, and installation operation also becomes easy.

  Further, in the damper D3 of this embodiment, the cylinder 1 in sliding contact with the piston 2 can be used as a strength member, and since the piston 2 does not receive an attack, the freedom of material selection of the housing 30 of the accumulator A1 is improved.

  Even in the damper D3 configured in this way, it is possible to adopt a structure in which the base valve is provided to the accumulator A1 like the damper D13 of the third modified example of the first embodiment, Like the damper D15 of the fifth modification and the damper D16 of the sixth modification, the application of the accumulator A1 to the damper of uniflow structure is also possible.

  While the preferred embodiments of the present invention have been described above in detail, modifications, variations and changes are possible without departing from the scope of the claims.

DESCRIPTION OF SYMBOLS 1 ... cylinder 2, 2 ... piston, 3 ... rod, 4, 40 ... outer cylinder, 10, 30 ... housing, 10a, 30a ... hole, 10b, 30b ... rectification Passages 11, 31 ... Free pistons 12, 32 ... Coil springs (spring elements) 16, 20 ... Damping passages 18, 21 ... Damping valves A, A1 ... Accumulators C: Sealed chamber, D1, D11, D12, D13, D14, D15, D16, D2, D21, D3: Damper, L: liquid chamber, R1: extension side chamber, R2: pressure side Chamber, S ... annular clearance,

Claims (6)

With the cylinder,
A piston which is slidably inserted in the cylinder and divides the inside of the cylinder into an expansion side chamber and a compression side chamber;
A rod inserted into the cylinder and coupled to the piston;
An outer cylinder disposed on the outer peripheral side of the cylinder to cover the cylinder and form an annular gap communicated with the cylinder between the cylinder and the outer cylinder;
And an accumulator installed in the annular gap,
The accumulator is
A housing provided with a hole communicating within the one or more annular gaps;
A free piston which is slidably inserted in the hole and which divides the inside of the hole into a fluid chamber and a closed chamber communicated with the annular gap;
And a spring element for biasing the free piston toward the liquid chamber. A cylindrical accumulator,
A piston slidably inserted into the accumulator to divide the accumulator into an expansion chamber and a compression chamber;
A rod inserted into the accumulator and coupled to the piston;
The accumulator is
A cylindrical housing in which the piston is slidably inserted in the inner circumference and which has one or more holes communicating with the inner circumference;
A free piston which is slidably inserted in the hole and which divides the inside of the hole into a fluid chamber communicated with the accumulator and a closed chamber;
And a spring element for biasing the free piston toward the liquid chamber. With the cylinder,
A piston which is slidably inserted in the cylinder and divides the inside of the cylinder into an expansion side chamber and a compression side chamber;
A rod inserted into the cylinder and coupled to the piston;
A cylindrical accumulator disposed on the outer periphery of the cylinder and covering the outer periphery of the cylinder;
The accumulator is
A housing provided with a bore in communication with the one or more cylinders;
A free piston which is slidably inserted into the hole and which divides the inside of the hole into a liquid chamber communicated with the cylinder and a closed chamber;
And a spring element for biasing the free piston toward the liquid chamber. The damper according to claim 1, wherein the housing has a straightening passage leading from one end to the other end. A plurality of the accumulators,
The damper according to claim 1 or 4, wherein the accumulator is axially arranged between the cylinder and the outer cylinder. The housing is
A damping passage communicating the fluid chamber with the interior of the cylinder or the accumulator;
The damper according to any one of claims 1 to 5, further comprising: a damping valve that resists the flow of liquid passing through the damping passage.

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