JP2020041650A - damper - Google Patents

Abstract

To provide a damper which enables easy optimization of characteristics of an accumulator and easy installation work.SOLUTION: A damper D1 of the invention includes: a cylinder 1; a piston 2 which is slidably inserted into the cylinder 1 and partitions an interior of the cylinder 1 into an expansion side chamber R1 and a pressure side chamber R2; a rod 3 which is inserted into the cylinder 1 and coupled to the piston 2; an outer cylinder 4 which forms a reservoir R communicating with the interior of the cylinder 1 with the cylinder 1; a cylindrical housing 5 housed in the reservoir R between the cylinder 1 and the outer cylinder 4; a closing member 6 which closes a space between one of the cylinder 1 and the outer cylinder 4 and the housing 5; a first free piston 7 which has an annular shape, slidably contacts with the one of the cylinder 1 and the outer cylinder 4 and the housing 5, and defines an air chamber G with the closing member 6 in between the one of the cylinder 1 and the outer cylinder 4 and the housing 5; and a spring element S which biases the first free piston 7 in a direction in which the air chamber G is expanded.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a damper.

  2. Description of the Related Art Dampers are widely used to suppress vibrations of damping targets such as machines, structures, and vehicles. The damper includes, for example, a cylinder, a piston slidably inserted into the cylinder to partition the inside of the cylinder into an extension side chamber and a compression side chamber, and a rod inserted into the cylinder and connected to the piston. In addition, a pressure difference is generated between the extension side chamber and the compression side chamber during expansion and contraction, and a damping force that resists expansion and contraction is exhibited.

  Normally, in the case of a single rod type, the damper compensates for the volume change due to the temperature change of the working liquid and the volume when the rod enters and exits the cylinder when the rod is a double rod type. A reservoir is provided for storing gas and working liquid to compensate for volume changes.

  In order for such a damper to exhibit the damping force as set irrespective of the mounting position on the damping target, it is necessary to prevent the gas in the reservoir from entering the cylinder. It is preferable that the accumulator has a structure that is separated so as not to mix with the working liquid.

  For example, if there is a damper in which an accumulator is formed in a rod, but there is no room in the installation space, the outer diameter of the damper is limited and the rod has to be reduced in diameter, and the capacity of the accumulator may not be secured ( For example, see 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 (for example, see Patent Document 2).

JP 2004-116552 A JP-A-11-82605

  By the way, when the damper is fully extended, it is necessary to make sure that the pressure inside the cylinder does not become lower than the atmospheric pressure. When the damper is fully contracted, the force for pushing the rod out of the cylinder by the pressure in the cylinder (rod It is necessary to take care that the reaction force does not become excessive. In order to satisfy such a demand, in a damper provided with an accumulator, a preload may be applied to the extension side chamber and the compression side chamber in the cylinder by the accumulator.

  However, the length and thickness of the cylinder and the outer cylinder are uniquely determined in design according to the installation space and the vibration damping target. As described above, if an attempt is made to use the space between the cylinder and the outer cylinder as an accumulator, the volume of the accumulator is uniquely determined by design. 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 an accumulator is provided separately from the outside of the damper, the size of the entire damper is increased and the asymmetric shape is required. The installation work is very troublesome because it may cause interference with parts.

  Therefore, an object of the present invention is to provide a damper that can easily optimize the characteristics of an accumulator and can be easily installed.

  In order to achieve the above object, a damper according to the present invention includes a cylinder, a piston slidably inserted into the cylinder to partition the cylinder into an extension side chamber and a compression side chamber, and a piston inserted into the cylinder and A rod connected to the cylinder, an outer cylinder disposed radially outside of the cylinder and covering the cylinder to form a reservoir communicated with the cylinder, and a reservoir between the cylinder and the outer cylinder. A cylindrical housing to be housed, a closing member for closing between one of the cylinder and the outer cylinder, and the housing, and an annular cylinder that slides on both the one of the cylinder and the outer cylinder and the housing. A first free piston movable axially between the one of the cylinder and the outer cylinder and the housing and defining an air chamber between the closing member and a first free piston in a direction to expand the air chamber. And a spring element for biasing the piston.

  The damper thus configured allows the reservoir to function as an accumulator, and can arbitrarily set the accumulator volume as long as it is allowed in the reservoir. Since the housing that functions as the accumulator, the closing member, the first free piston and the spring element are housed in the reservoir between the cylinder and the outer cylinder, it is possible to avoid an increase in the size of the damper and an asymmetric shape, When the damper is installed in the installation space, interference with other components does not occur.

  The damper may be a second free piston in which the closing member has an annular shape and is slidably in contact with one of the cylinder and the outer cylinder and the housing and is axially movable with respect to both. In the damper configured as described above, the housing is positioned in the radial direction by the closing member that functions as the first free piston and the second free piston that is in sliding contact with the cylinder, and the housing has a simple tube structure that easily provides dimensional accuracy. Therefore, the accumulator can be configured in the reservoir without requiring precise processing, and the manufacturing cost is reduced.

  The closing member of the damper includes a cylinder fitting portion fitted to one end of a cylinder formed by a step portion, a housing fitting portion fitted to one end of the housing formed by the step portion, and a stepped portion. An outer cylinder fitting portion to which one end of the outer cylinder is fitted. In the damper configured as described above, since the rod guide, which is a component generally required for the damper, can be used as the closing member, the number of components can be reduced when forming the air chamber, and the assemblability of the damper is improved. Thus, the damper can be manufactured at lower cost.

  Further, the spring element is a coil spring, and the closing member is fitted to one end of the coil spring to position a radial position of one end of the coil spring at a position separated from both the cylinder and one of the outer cylinder and the housing. The first free piston is fitted to the other end of the coil spring to separate the radial position of the other end of the coil spring from both the cylinder, one of the outer cylinder, and the housing. May be provided at the first free piston side aligning portion positioned at a position where the first free piston moves. According to the damper configured in this manner, the interference of the spring element with one of the cylinder and the outer cylinder and the housing can be prevented, and the one of the cylinder and the outer cylinder and the housing can be protected. Can smoothly move in the axial direction with respect to one of the cylinder and the outer cylinder and the housing 5.

  The damper may be configured such that the spring element applies an initial load to the closing member and the first free piston in a state where the closing member and the first free piston are maximally separated in the axial direction. According to the damper configured as described above, even when the contraction operation is performed after the extension operation, the compression-side damping force can be exhibited with good responsiveness, and the occurrence of "running" can be suppressed.

  Further, the damper is configured to reduce the surface hardness of the sliding surface of the first free piston that slides into contact with one of the cylinder and the outer cylinder and the housing, and the surface hardness of the sliding surface that slides with the first free piston of the cylinder and one of the outer cylinder and the housing. It may be configured to be smaller. According to the damper thus configured, the first free piston easily slides with respect to one of the cylinder and the outer cylinder and the housing, and a smooth expansion and contraction operation is also realized.

  ADVANTAGE OF THE INVENTION According to the damper of this invention, optimization of the characteristic of an accumulator is easy and installation work also becomes easy.

It is sectional drawing of the damper in 1st Embodiment. It is sectional drawing of the damper in the 1st modification of 1st Embodiment. It is sectional drawing of the damper in 2nd Embodiment.

  Hereinafter, the present invention will be described based on the embodiment shown in the drawings. Note that the same reference numerals are given to configurations common to the dampers D1 and D2 of each embodiment described below, and to avoid duplication of description, the configuration described in the description of the damper D1 of one embodiment will be described. In the description of the damper D2 of another embodiment, detailed description is omitted.

<First embodiment>
As shown in FIG. 1, the damper D1 in the first embodiment includes a cylinder 1 and a piston 2 slidably inserted into the cylinder 1 to partition the inside of the cylinder 1 into an extension chamber R1 and a compression chamber R2. A rod 3 inserted into the cylinder 1 and connected to the piston 2; an outer cylinder 4 disposed radially outside the cylinder 1 to cover the cylinder 1 and form a reservoir R between the cylinder 1 and A cylindrical housing 5 housed in a reservoir R between the cylinder 1 and the outer cylinder 4; a closing member 6 for closing between the cylinder 1 and one end of the housing 5; A first free piston 7 that partitions the air chamber G with the closing member 6 and a spring element S that urges the first free piston 7 in a direction to expand the air chamber G are provided.

  Hereinafter, each part of the damper D1 will be described in detail. A rod guide 8 is fitted to one end of the cylinder 1, and a valve case 9 is fitted to the other end. An outer cylinder 4 is provided radially outside the cylinder 1 to form a reservoir R that covers the outer periphery of the cylinder 1 and communicates with the cylinder 1 and communicates with the cylinder 1. One end of the outer cylinder 4 is closed by a rod guide 8, the other end of the outer cylinder 4 is closed by a valve case 9, and a cap 10 is attached. The cylinder 1 is sandwiched and fixed by a rod guide 8 mounted on the outer cylinder 4 and a valve case 9 abutting on the cap 10 while being housed in the outer cylinder 4.

  The piston 2 is slidably inserted into the cylinder 1 and divides the inside of the cylinder 1 into an extension chamber R1 and a compression chamber R2. Each of the expansion side chamber R1 and the compression side chamber R2 is filled with a working oil as a working liquid. In this example, the working liquid is hydraulic oil, but may be another liquid such as water or an aqueous solution.

  The piston 2 includes a rectifying passage 2a that communicates between the expansion side chamber R1 and the compression side chamber R2, and a check valve 2b that is provided in the rectification passage 2a and allows only the flow of hydraulic oil from the compression side chamber R2 to the expansion side chamber R1. ing.

  Further, the rod guide 8 is annular and includes a cylinder fitting portion 8a fitted into the cylinder 1 and an outer cylinder fitting portion 8b fitted to the inner periphery of the outer cylinder 4. Further, the rod guide 8 is opened from the right end in FIG. 1 of the cylinder fitting portion 8a, communicates with the right end in FIG. 1 of the outer cylinder fitting portion 8b, and communicates with the extension side chamber R1 and the reservoir R; A damping valve 8d is provided in the discharge passage 8c to allow only the flow of hydraulic oil from the extension side chamber R1 to the reservoir R and to provide resistance to the flow of hydraulic oil passing therethrough. In the present embodiment, the discharge passage 8c and the damping valve 8d form a damping passage DP.

  Further, the valve case 9 includes a small-diameter portion 9a fitted in the cylinder 1 and a large-diameter portion 9b fitted on the inner periphery of the outer cylinder 4. The valve case 9 has a suction passage 9c which opens from the left end of the small diameter portion 9a in FIG. 1 and communicates with the pressure chamber R2 and the reservoir R through the left end of the large diameter portion 9b in FIG. A check valve 9d that is installed and allows only the flow of hydraulic oil from the reservoir R toward the pressure side chamber R2.

  One end of the rod 3 is movably inserted into the cylinder 1 through the rod guide 8, is connected to the piston 2, and has the other end protruding 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 extension side chamber R1, but it is also inserted into the compression side chamber R2 so that both ends of the rod 3 are both ends of the cylinder 1. So-called double-rod type dampers projecting outward from the respective members. The damper D1 is provided with brackets 3a and 9e at both ends of the rod 3 and the cap 10 so that the damper D1 can be connected to a vibration damping target.

  The housing 5 has an inner diameter larger than the outer diameter of the cylinder 1 and an outer diameter smaller than the inner diameter of the outer cylinder 4, and is housed between the cylinder 1 and the outer cylinder 4. The housing 5 includes C-rings 5c and 5d mounted on annular grooves 5a and 5b formed on the inner circumferences at both ends. In addition, a gap is formed between the housing 5 and the outer cylinder 4 to allow passage of hydraulic oil.

  The closing member 6 is annular and includes seal rings 6c and 6d mounted in annular grooves 6a and 6b provided on the inner and outer circumferences, respectively. The closing ring 6 is provided on the outer circumference of the cylinder 1 and the inner circumference of the housing 5, respectively. The second free piston is allowed to slide in the axial direction with respect to both the cylinder 1 and the housing 5 by sliding contact. When the closing member 6 is inserted between the cylinder 1 and the housing 5, the closing member 6 slides on the cylinder 1 and the housing 5 to close the gap between the cylinder 1 and one end of the housing 5. When the closing member 6 comes into contact with a C-ring 5c provided at the left end of the housing 5, further movement of the closing member 6 to the left in FIG. The closing member 6 includes an annular closing member-side centering portion 6e that protrudes toward the air chamber G from the right end of the air chamber G in FIG.

  The first free piston 7 is annular and includes seal rings 7c and 7d mounted in annular grooves 7a and 7b provided on the inner and outer circumferences, respectively. The outer circumference of the cylinder 1 and the inner circumference of the housing 5 are provided. Are allowed to slide in the axial direction with respect to both the cylinder 1 and the housing 5. When the first free piston 7 is inserted between the cylinder 1 and the housing 5, the first free piston 7 slides on the cylinder 1 and the housing 5, closes the gap between the cylinder 1 and one end of the housing 5, and closes the cylinder 1 and the housing 5. The air chamber G is defined between the space 5 and the closing member 6 in cooperation with the closing member 6. When the first free piston 7 abuts on a C-ring 5d provided at the right end of the housing 5, further movement of the first free piston 7 to the right in FIG. In addition, the first free piston 7 includes an annular first free-piston-side aligning portion 7e protruding from the left end of the air chamber G in FIG.

  As described above, the closing member 6 abuts on the C ring 5c on the left end side of the housing 5 in FIG. 1 so that the movement to the left with respect to the housing 5 is restricted, and the first free piston 7 is The rightward movement of the housing 5 is restricted by contacting the C ring 5d on the right side of the center 1. Therefore, the closing member 6 and the first free piston 7 are prevented from coming out of the housing 5 by the C rings 5c and 5d. The blocking of the closing member 6 and the first free piston 7 from the housing 5 may be prevented by a component that can function as a stopper other than the C-ring, and the stopper may be provided in the cylinder 1.

  There is no limitation on the setting of the surface hardness on the sliding surfaces of the closing member 6, the first free piston 7, the cylinder 1 and the housing 5, but the closing member 6 and the cylinder 1 and the housing 5 of the first free piston 7 are smoother. In order to move in the axial direction, the following operation may be performed. Specifically, the surface hardness of the sliding contact surface of the closing member 6 and the first free piston 7 sliding on the cylinder 1 and the housing 5 is determined by the sliding contact surface of the closing member 6 of the cylinder 1 and the first free piston 7 sliding on each other. The surface hardness of an inner peripheral surface which is a sliding contact surface between a certain outer peripheral surface, a closing member 6 of the housing 5 and the first free piston 7 is made softer (lower). In the present embodiment, the closing member 6 and the first free piston 7 are formed of a material having a lower hardness (softer hardness) than the material of the cylinder 1 and the housing 5. As described above, when the surface hardness of the sliding contact surface between the closing member 6 and the first free piston 7 is made softer than the surface hardness of the sliding contact surface between the cylinder 1 and the housing 5, the closing member 6 and the first free piston 7 become the cylinder. 1 and the housing 5 are easily slid, so that the closing member 6 and the first free piston 7 can move smoothly in the axial direction. In addition to changing the materials of the closing member 6, the first free piston 7, the cylinder 1, and the housing 5, the sliding surface may be subjected to a surface treatment to set the surface hardness as described above.

  The air chamber G formed on the outer periphery of the cylinder 1 and between the housing 5, the closing member 6 and the first free piston 7 is provided with a seal ring 6c provided on the closing member 6 as a second free piston. 6d and the seal rings 7c and 7d provided on the first free piston 7 are airtightly held. Note that gas is sealed in the air chamber G.

  In the present embodiment, the spring element S is a coil spring, one end of which is fitted on the outer periphery of the closing member-side aligning portion 6e provided on the closing member 6, and the other end of which is connected to the first free piston 7. It is fitted to the outer periphery of the provided first free piston side aligning portion 7e. The spring element S is interposed between the closing member 6 and the first free piston 7 in this manner, and is a direction in which the closing member 6 and the first free piston 7 are separated from each other in the axial direction. Is urged to expand. Further, even when the damper D1 is fully extended, the spring element S is pressed by the hydraulic oil stored in the reservoir R via the closing member 6 and the first free piston 7 and is compressed from its natural length. Thus, both the closing member 6 and the first free piston 7 are urged in the direction in which the air chamber G is enlarged, and an initial load is applied. When the damper D1 is in the maximum extension state, the amount of hydraulic oil in the reservoir R is the minimum, and the closing member 6 and the first free piston 7 are most separated in the axial direction to maximize the volume of the air chamber G. However, the spring element S is in a compressed state and urges the closing member 6 and the first free piston 7 in a direction to be separated. Therefore, the spring element S always urges both the closing member 6 and the first free piston 7 in the direction of expanding the air chamber G.

  The outer diameters of the closing member side aligning portion 6e and the first free piston side aligning portion 7e into which the spring element S fits are smaller than the inner diameter of the housing 5, and the outer diameter of the spring element S is also smaller than that of the housing. 5 is smaller than the inner diameter. Therefore, the radial position of one end of the spring element S is positioned at a position separated from both the cylinder 1 and the housing 5 by the closing member side alignment portion 6e, and the radial position of the other end of the spring element S is The first free piston side centering portion 7e is positioned at a position separated from both the cylinder 1 and the housing 5. Since the spring element S, which is a coil spring, is positioned at a position radially separated from both the cylinder 1 and the housing 5, interference of the spring element S with the cylinder 1 and the housing 5 is prevented. In the present embodiment, the spring element S is fitted on the outer periphery of the closing member side aligning portion 6e and the outer periphery of the first free piston side aligning portion 7e. The inner peripheral diameter of the free piston side aligning portion 7e is made larger than the outer diameter of the cylinder 1, and the outer periphery of the spring element S is formed on the inner peripheral surfaces of the closing member side aligning portion 6e and the first free piston side aligning portion 7e. They may be fitted. In this case, if the inner diameter of the spring element S, which is a coil spring, is made larger than the outer diameter of the cylinder 1, the interference of the spring element S with the cylinder 1 and the housing 5 can be prevented. The closing member-side aligning portion 6e and the first free piston-side aligning portion 7e only have to play a role of positioning the spring element S, which is a coil spring, in the radial direction. The fitting structure may be adopted. When both the closing member side aligning portion 6e and the first free piston side aligning portion 7e are fitted to the inner periphery or the outer periphery of the spring element S, the closing member 6 Since the first free piston 7 and the first free piston 7 can be formed in the same shape, parts management in manufacturing is simplified, and the manufacturing cost is reduced.

  The spring element S may be an air spring composed of the air chamber G and the gas filled in the air chamber G instead of the coil spring. As described above, when the spring element S is formed by an air spring, the closing member-side aligning portion 6e provided on the closing member 6 and the first free piston-side aligning portion 7e provided on the first free piston 7 are unnecessary. is there.

  The damper D1 is configured as described above, and the operation of the damper D1 will be described below. First, the operation when the damper D1 performs the extension operation will be described. When the damper D1 extends and the piston 2 moves leftward in FIG. 1 with respect to the cylinder 1, the expansion-side chamber R1 is compressed, and the volume of the compression-side chamber R2 is increased. Then, the hydraulic oil in the expansion side chamber R1 to be compressed moves to the reservoir R through the damping passage DP. Further, hydraulic oil is supplied from the reservoir R to the expanding pressure side chamber R2 via the suction passage 9c.

  Then, the damping valve 8d gives resistance to the flow of hydraulic oil from the expansion side chamber R1 to the reservoir R via the above-described attenuation passage DP, so that the pressure in the expansion side chamber R1 increases, while the compression side chamber R2 is It becomes equal to the pressure in the reservoir R. Therefore, a difference is generated between the pressures of the extension side chamber R1 and the compression side chamber R2, and the damper D1 exerts an extension side damping force in a direction that hinders the extension operation according to the pressure difference.

  During the extension operation of the damper D1, the amount of hydraulic oil in the reservoir R decreases in order to supply the cylinder 1 with hydraulic oil of a volume that allows the rod 3 to withdraw from the cylinder 1, but the hydraulic fluid decreases in the reservoir R. One or both of the free pistons 7 move in the direction away from the housing 5 to increase the volume of the air chamber G by the reduced amount of hydraulic oil. As described above, when the damper D <b> 1 extends, the volume of the rod 3 withdrawing from the cylinder 1 is increased by the one or both of the closing member 6 and the first free piston 7 with respect to the housing 5 so as to enlarge the air chamber G. Compensated for moving.

  The operation when the damper D1 performs the contraction operation will be described. When the damper D1 contracts and the piston 2 moves rightward in FIG. 1 with respect to the cylinder 1, the compression-side chamber R2 is compressed and the volume of the expansion-side chamber R1 is increased. Then, the hydraulic oil in the compression side chamber R2 to be compressed pushes open the check valve 2b, passes through the straightening passage 2a, and moves to the expansion side chamber R1. Further, the amount of hydraulic oil corresponding to the volume of the rod 3 entering the cylinder 1 becomes excessive in the cylinder 1, and the excess hydraulic oil is discharged to the reservoir R via the damping passage DP. Then, the damping valve 8d gives resistance to the flow of the hydraulic oil from the expansion side chamber R1 to the reservoir R via the above-described attenuation path DP, so that the pressures of the expansion side chamber R1 and the compression side chamber R2 both increase equally. . In the present embodiment, the damper D1 is a single-rod damper, and has a pressure-receiving area on the compression-side chamber R2 side larger than the pressure-receiving area on the expansion-side chamber R1 side of the piston 2, so that the damper D1 exhibits a compression-side damping force that hinders the contraction operation. I do.

  During the contraction operation of the damper D1, since the rod 3 enters the cylinder 1, the amount of hydraulic oil corresponding to the volume of the rod 3 entering the cylinder 1 is discharged from the cylinder 1 to the reservoir R. Therefore, although the amount of hydraulic oil increases in the reservoir R, the closing member 6 and the first free piston 7 move in the direction approaching each other with respect to the housing 5, and the amount of hydraulic oil integrated by the increased amount of the air chamber G increases. Reduce the volume. As described above, when the damper D <b> 1 is contracted, the volume of the rod 3 entering the cylinder 1 is such that one or both of the closing member 6 and the first free piston 7 are moved relative to the housing 5 so as to reduce the air chamber G. Compensated for moving.

  The amount of hydraulic oil in the reservoir R is the smallest when the damper D1 extends the most, and becomes the largest when the damper D1 contracts the most. Therefore, the closing member 6 and the first free piston 7 are most separated from each other when the damper D1 extends most, to maximize the volume of the air chamber G, and come closest to each other when the damper D1 contracts most. The volume of Even when the damper D1 is fully extended, the movement of the closing member 6 and the first free piston 7 is not restricted by the C rings 5c and 5d of the housing 5, and the damper D1 is fully contracted. Also, the amount of hydraulic oil in the reservoir R and the capacity of the air chamber G are set so that the spring element S does not have a close contact length. Therefore, the operating oil in the reservoir R is pressurized through the closing member 6 and the first free piston 7 by the resilient force exerted by the gas in the spring element S and the air chamber G. That is, the reservoir R functions as an accumulator by the cylinder 1, the housing 5, the closing member 6, the first free piston 7, and the spring element S, and constantly pressurizes the inside of the cylinder 1 that is communicated with the reservoir R. It compensates for the volume of the rod 3 going in and out. In addition, even if the housing 5 is sufficiently long and the damper D1 is fully extended and the volume of the air chamber G is maximized, the amount of hydraulic oil is adjusted so that the closing member 6 and the first free piston 7 do not fall out of the housing 5. If the natural length and the spring constant of the spring element S are set, the C-rings 5c and 5d functioning as stoppers for the closing member 6 and the first free piston 7 can be omitted.

  As described above, the damper D1 of the present invention is inserted into the cylinder 1, the piston 2 which is slidably inserted into the cylinder 1, and defines the extension side chamber R1 and the compression side chamber R2 inside the cylinder 1, and the cylinder 1. A rod 3 connected to the piston 2, an outer cylinder 4 disposed outside the cylinder 1 and forming a reservoir R that covers the cylinder 1 and communicates with the cylinder 1 and the cylinder 1; A cylindrical housing 5 housed in a reservoir R between the outer cylinder 4, a closing member 6 for closing between the cylinder 1 and the housing 5, a ring-shaped closing member 6 for both the cylinder 1 and the housing 5. A first free piston 7 which is slidably movable in the axial direction with respect to the two and which defines an air chamber G between the cylinder 1 and the housing 5 and between the closing member 6; In the direction of And a spring element S for biasing the piston 7.

  The damper D1 configured as described above allows the reservoir R to function as an accumulator, and can arbitrarily set the accumulator volume as long as it is allowed in the reservoir R. Therefore, in the damper D1 of the present invention, the accumulator volume can be adjusted so that the rod reaction force is appropriate from the maximum extension to the maximum contraction, and the accumulator characteristics can be tuned so as to be optimal for the damper D1.

  Further, since the housing 5, the closing member 6, the first free piston 7, and the spring element S for making the reservoir R function as an accumulator are accommodated in the reservoir R between the cylinder 1 and the outer cylinder 4, the size of the damper D1 is large. It can be avoided that the damper D1 is mounted on the installation space without interference with other components. As described above, according to the damper D1 of the present invention, it is easy to optimize the accumulator characteristics, and the installation work is also easy.

  Further, in the damper D1 of the present embodiment, the closing member 6 is a second free piston. In the damper D1 configured as described above, the housing 5 is positioned in the radial direction by the first free piston 7 that slides on the cylinder 1 and the closing member 6 that functions as the second free piston, so that the housing 5 can easily achieve dimensional accuracy. Since it has a simple pipe structure, an accumulator can be formed in the reservoir R without requiring precise processing. Therefore, according to the damper D1 of the present invention, the manufacturing cost is also reduced.

  Further, in the damper D1 of the present embodiment, the spring element S is a coil spring, and the closing member 6 is fitted to one end of the coil spring (spring element S) so that the diameter of one end of the coil spring (spring element S) is increased. It has a closing member side aligning portion 6e for positioning the directional position at a position separated from both the cylinder 1 and the housing 5, and the first free piston 7 is fitted to the other end of the coil spring (spring element S). And a first free piston side centering portion 7e for positioning the other end of the coil spring (spring element S) in the radial direction at a position separated from both the cylinder 1 and the housing 5. According to the damper D1 configured as described above, the interference of the spring element S with the cylinder 1 and the housing 5 can be prevented, the cylinder 1 and the housing 5 can be protected, and the closing member 6 and the first free piston 7 can be used for a long time. And can smoothly move in the axial direction with respect to the cylinder 1 and the housing 5.

  Then, in the damper D1 of the present embodiment, the spring element S initially moves the closing member 6 and the first free piston 7 in a state where the closing member 6 and the first free piston 7 are maximally separated in the axial direction. Applying a load. In the damper D1 configured as described above, since the inside of the reservoir R is constantly pressurized, the hydraulic oil can be sufficiently supplied from the reservoir R into the pressure side chamber R2 that expands when the damper D1 extends, and the pressure in the cylinder 1 can be increased. Poor suction of hydraulic oil is less likely to occur. Therefore, even when the damper D1 performs the contraction operation after the extension operation, the pressure in the cylinder 1 is quickly increased, so that the damper D1 can exhibit the compression-side damping force with good responsiveness. More specifically, if a suction failure occurs in the cylinder 1 during the extension operation of the damper D1, the pressure in the cylinder 1 does not increase easily when the damper D1 changes from the extension operation to the contraction operation, and the pressure-side damping force is exerted temporally. A phenomenon referred to as "running" occurs, but when the spring element S applies an initial load to the closing member 6 and the first free piston 7 as described above, occurrence of "running" can be suppressed. It is.

  Furthermore, in the damper D1 of the present embodiment, the surface hardness of the sliding surface of the first free piston 7 that slides on the cylinder 1 and the housing 5 is determined by the surface hardness of the sliding surface of the cylinder 1 and the housing 5 on which the first free piston 7 slides. Softer than surface hardness. According to the damper D1 configured as described above, the first free piston 7 easily slides with respect to the cylinder 1 and the housing 5, and a smooth expansion and contraction operation is also realized.

  Note that, instead of the configuration of the damper D1 shown in FIG. 1, the closing member 6 and the first free piston 7 are provided between the outer cylinder 4 and the housing 5 like the damper D2 of the first modification shown in FIG. The air chamber G may be formed by inserting and sliding in contact with both the inner circumference of the outer cylinder 4 and the outer circumference of the housing 5. In the damper D1, the air chamber G is formed using the cylinder 1. However, the air chamber G may be formed using the outer cylinder 4 instead of the cylinder 1, as in the damper D2 shown in FIG. Also in this case, the damper D2 allows the reservoir R to function as an accumulator, and can arbitrarily set the accumulator volume as long as it is allowed in the reservoir R. Therefore, in the damper D2 of the present invention, the accumulator volume can be adjusted so that the rod reaction force is appropriate from the maximum extension to the maximum contraction, and the accumulator characteristics can be tuned to be optimal for the damper D2.

  Further, since the housing 5, the closing member 6, the first free piston 7, and the spring element S for making the reservoir R function as an accumulator are housed in the reservoir R between the cylinder 1 and the outer cylinder 4, the size of the damper D2 is large. It can be avoided that the damper D2 is installed in the installation space without causing interference with other components. As described above, according to the damper D2 of the present invention, it is easy to optimize the accumulator characteristics, and the installation work is also easy.

  Further, even with the damper D2, the advantage that the closing member 6 is the second free piston is obtained. The spring element S is a coil spring, and the closing member 6 is provided with the closing member-side centering portion 6e. The first free piston side centering portion 7e is provided, and the closing member 6 and the first free piston 7 are arranged so that the spring element S is maximally separated in the axial direction between the closing member 6 and the first free piston 7. The advantage of applying an initial load to (1) and (2) can be enjoyed similarly to the damper D1 of the first embodiment. In the damper D2, the surface hardness of the sliding surface of the first free piston 7 that slides on the outer cylinder 4 and the housing 5 is set to the surface hardness of the sliding surface of the outer cylinder 4 and the first free piston 7 on the housing 5 that slides. When the first free piston 7 is softer than the surface hardness, the first free piston 7 slides easily with respect to the outer cylinder 4 and the housing 5, and a smooth expansion and contraction operation is also realized.

<Second embodiment>
As shown in FIG. 3, a damper D3 according to the second embodiment includes a cylinder 1 and a piston 2 which is slidably inserted into the cylinder 1 to partition 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 connected to the piston 2; an outer cylinder 4 disposed radially outside the cylinder 1 to cover the cylinder 1 and form a reservoir R between the cylinder 1 and A cylindrical housing 5 housed in a reservoir R between the cylinder 1 and the outer cylinder 4; a rod guide 8 as a closing member for closing between the cylinder 1 and one end of the housing 5; 5, a first free piston 7 defining an air chamber G between the rod guide 8 and the rod guide 8, and a spring element S for urging the first free piston 7 in a direction to expand the air chamber G. I have.

  That is, in the damper D3 of the second embodiment, the rod guide 8 is used as a closing member, and the housing 5 is fitted to the rod guide 8 together with the cylinder 1 so that the rod guide 8 serves as a closing member for the air chamber G. It functions as a member to be formed. Other structures of the damper D3 are the same as those of the damper D1. Hereinafter, only a portion where the damper D3 is different from the damper D1 will be described in detail.

  The rod guide 8 is annular and has a cylinder fitting portion 8a fitted into the cylinder 1, an outer cylinder fitting portion 8b fitted on the inner periphery of the outer cylinder 4, a cylinder fitting portion 8a and the outer cylinder. A housing fitting portion 8e formed of a step provided between the fitting portion 8b and a closing member side aligning portion formed of a step provided between the cylinder fitting portion 8a and the housing fitting portion 8e. 8f. That is, the rod guide 8 of the present embodiment has four steps on the outer periphery, and these steps allow the cylinder fitting portion 8a having the smallest outside diameter and the closing member side adjustment having the second smallest outside diameter. A core portion 8f, a housing fitting portion 8e having the third smallest outer diameter, and an outer cylinder fitting portion 8b having the largest outer diameter among the fitting portions are provided.

  One end of the cylinder 1 is fitted to the cylinder fitting portion 8a of the rod guide 8, and one end of the housing 5 is fitted to the outer periphery of the housing fitting portion 8e of the rod guide 8. And one end of the housing 5 is closed by a rod guide 8. Since the housing 5 is fitted to the rod guide 8 and does not move relative to the rod guide 8, the C ring 5c provided on the housing 5 in the damper D1 is eliminated.

  A first free piston 7 that slides on both the cylinder 1 and the housing 5 is inserted between the cylinder 1 and the housing 5, and between the cylinder 1 and the housing 5, An air chamber G is formed between one free piston 7. Sealing rings 8g and 8h are mounted in annular grooves (not shown) provided on the outer periphery of the cylinder fitting portion 8a and the housing fitting portion 8e, respectively, between the cylinder 1 and the rod guide 8, and between the cylinder 1 and the rod guide 8. The space between the rod guide 8 and the rod guide 8 is sealed, and the air chamber G is kept airtight.

  Further, the spring element S is a coil spring, and one end, which is the left end in FIG. 3, of the spring element S is fitted to the outer periphery of the closing member-side centering portion 8 f of the rod guide 8. The other end, which is the right end in FIG. 3, of the spring element S is fitted on the outer periphery of the first free piston-side aligning portion 7 e of the first free piston 7. Therefore, the spring element S is positioned in the radial direction by the rod guide 8 and the first free piston 7 serving as the closing member, and the interference between the cylinder 1 and the housing 5 is prevented.

  The spring element S is interposed between the rod guide 8 which is a closing member and the first free piston 7, and is a direction in which the first free piston 7 is separated from the rod guide 8 in the axial direction. The room G is urged in a direction to expand. Further, even when the damper D3 is fully extended, the spring element S is pressed by the hydraulic oil stored in the reservoir R via the rod guide 8 and the first free piston 7 and is compressed from its natural length. Thus, the first free piston 7 is urged in a direction to expand the air chamber G to apply an initial load. When the damper D3 is in the maximum extension state, the amount of hydraulic oil in the reservoir R is the minimum, and the rod guide 8 and the first free piston 7 are most separated in the axial direction to maximize the volume of the air chamber G. However, the spring element S is in a compressed state and urges the rod guide 8 and the first free piston 7 in a direction to be separated. Therefore, the spring element S always urges the first free piston 7 in a direction to expand the air chamber G.

  The damper D3 is configured as described above, and the operation of the damper D3 will be described below. First, the operation when the damper D3 performs the extension operation will be described. When the damper D3 extends and the piston 2 moves leftward in FIG. 3 with respect to the cylinder 1, the expansion-side chamber R1 is compressed, and the volume of the compression-side chamber R2 is increased. Then, the hydraulic oil in the expansion side chamber R1 to be compressed moves to the reservoir R through the damping passage DP. Further, hydraulic oil is supplied from the reservoir R to the expanding pressure side chamber R2 via the suction passage 9c.

  Then, the damping valve 8d gives resistance to the flow of hydraulic oil from the expansion side chamber R1 to the reservoir R via the above-described attenuation passage DP, so that the pressure in the expansion side chamber R1 increases, while the compression side chamber R2 is It becomes equal to the pressure in the reservoir R. Therefore, a difference is generated between the pressure in the expansion side chamber R1 and the pressure in the compression side chamber R2, and the damper D3 exerts an expansion side damping force in a direction that hinders the expansion operation according to the pressure difference.

  During the extension operation of the damper D3, the amount of hydraulic oil in the reservoir R decreases in order to supply the hydraulic oil of the volume of the rod 3 withdrawing from the cylinder 1 into the cylinder 1, but the first free piston 7 The air chamber G is moved in a direction away from the rod guide 8 which is a closing member, and the volume of the air chamber G is increased by the reduced amount of hydraulic fluid. As described above, when the damper D3 extends, the volume of the rod 3 withdrawing from the cylinder 1 is compensated for because the first free piston 7 moves with respect to the housing 5 so as to enlarge the air chamber G.

  The operation when the damper D3 contracts will be described. When the damper D3 contracts and the piston 2 moves rightward in FIG. 3 with respect to the cylinder 1, the compression-side chamber R2 is compressed and the volume of the expansion-side chamber R1 is increased. Then, the hydraulic oil in the compression side chamber R2 to be compressed pushes open the check valve 2b, passes through the straightening passage 2a, and moves to the expansion side chamber R1. Further, the amount of hydraulic oil corresponding to the volume of the rod 3 entering the cylinder 1 becomes excessive in the cylinder 1, and the excess hydraulic oil is discharged to the reservoir R via the damping passage DP. Then, the damping valve 8d gives resistance to the flow of the hydraulic oil from the expansion side chamber R1 to the reservoir R via the above-described attenuation path DP, so that the pressures of the expansion side chamber R1 and the compression side chamber R2 both increase equally. . In the present embodiment, the damper D3 is a single-rod type damper, and has a pressure-receiving area on the compression-side chamber R2 side larger than the pressure-receiving area on the extension-side chamber R1 side of the piston 2, and thus exhibits a compression-side damping force that prevents the contraction operation. I do.

  During the contraction operation of the damper D3, since the rod 3 enters the cylinder 1, the amount of hydraulic oil corresponding to the volume of the rod 3 entering the cylinder 1 is discharged from the cylinder 1 to the reservoir R. Therefore, although the amount of hydraulic oil increases in the reservoir R, the first free piston 7 moves in a direction in which the first free piston 7 approaches the rod guide 8 which is a closing member, and the amount of the hydraulic oil in the air chamber G is increased by the increased amount of hydraulic oil. Reduce the volume. As described above, at the time of the contraction operation of the damper D <b> 3, the volume of the rod 3 entering the cylinder 1 is such that one or both of the closing member 6 and the first free piston 7 are moved relative to the housing 5 so as to reduce the air chamber G. Compensated for moving.

  The amount of hydraulic oil in the reservoir R is the smallest when the damper D3 extends the most, and becomes the largest when the damper D3 contracts the most. Therefore, the first free piston 7 maximizes the volume of the air chamber G by farthest from the rod guide 8 when the damper D3 extends most, and becomes closest to the rod guide 8 when the damper D3 contracts most. Minimize the volume of chamber G. In addition, even when the damper D3 is fully extended, the movement of the first free piston 7 is not restricted by the C-ring 5d of the housing 5, and even when the damper D3 is fully contracted, the spring element S is in tight contact. The hydraulic oil amount in the reservoir R and the capacity of the air chamber G are set so as not to be long. Therefore, the hydraulic oil in the reservoir R is pressurized via the first free piston 7 by the resilient force exerted by the gas in the spring element S and the gas in the air chamber G. That is, the reservoir R functions as an accumulator by the cylinder 1, the housing 5, the rod guide 8, the first free piston 7, and the spring element S, and constantly pressurizes the inside of the cylinder 1 that is communicated with the reservoir R. It compensates for the volume of the rod 3 going in and out. In addition, even if the housing 5 is sufficiently long and the damper D3 is fully extended and the volume of the air chamber G is maximized, the spring element S of the hydraulic oil amount is set so that the first free piston 7 does not fall out of the housing 5. If the natural length and the spring constant are set, the C ring 5d functioning as a stopper for the first free piston 7 can be omitted.

  As described above, the damper D3 of the present invention is inserted into the cylinder 1, the piston 2 which is slidably inserted into the cylinder 1, and defines the extension side chamber R1 and the compression side chamber R2 inside the cylinder 1, and the cylinder 1. A rod 3 connected to the piston 2, an outer cylinder 4 disposed outside the cylinder 1 and forming a reservoir R that covers the cylinder 1 and communicates with the cylinder 1 and the cylinder 1; A cylindrical housing 5 housed in a reservoir R between the outer cylinder 4, a rod guide (closing member) 8 for closing between the cylinder 1 and the housing 5, an annular cylinder 1 and a housing 5 And a first free piston which is slidably in contact with both of them and is axially movable with respect to both of them, and defines an air chamber G between the cylinder 1 and the housing 5 and between the rod guide (closing member) 8. 7 and And a spring element S for biasing the first free piston 7 in the direction to expand the air chamber G.

  The damper D3 configured as described above allows the reservoir R to function as an accumulator, and can arbitrarily set the accumulator volume as long as it is allowed in the reservoir R. Therefore, in the damper D3 of the present invention, the accumulator volume can be adjusted so that the rod reaction force is appropriate from the maximum extension to the maximum contraction, and the accumulator characteristics can be tuned so as to be optimal for the damper D3.

  Further, the housing 5, the rod guide (blocking member) 8, the first free piston 7, and the spring element S that make the reservoir R function as an accumulator are housed in the reservoir R between the cylinder 1 and the outer cylinder 4, so that It is possible to avoid an increase in the size of the damper D3 and an asymmetric shape, and it is possible to avoid interference with other components when the damper D3 is mounted in the installation space. As described above, according to the damper D3 of the present invention, it is easy to optimize the accumulator characteristics, and the installation work is also easy.

  In the damper D3 of the present embodiment, the rod guide (blocking member) 8 is formed in a stepped portion and the cylinder fitting portion 8a in which the cylinder is fitted, and the housing 5 formed in the stepped portion is fitted. It has a housing fitting portion 8e and an outer tube fitting portion 8b formed of a step portion and fitted with the outer tube 4. In the damper D3 configured as described above, a component (rod guide 8) generally required for the damper can be used as the closing member, so that the number of components can be reduced in forming the air chamber G, and the assembling property of the damper D3 can be reduced. And the damper D3 can be manufactured at lower cost.

  Further, in the damper D3 of the present embodiment, the spring element S is a coil spring, and the rod guide (closing member) 8 is fitted to one end of the coil spring (spring element S) and is connected to the coil spring (spring element S). Has a closing member side aligning portion 8f for positioning a radial position of one end of the coil spring at a position separated from both the cylinder 1 and the housing 5, and the first free piston 7 is provided at one end of the coil spring (spring element S). It has a first free piston side centering portion 7e that fits and positions one end of the coil spring (spring element S) in a radial direction at a position separated from both the cylinder 1 and the housing 5. According to the damper D3 configured as described above, the interference of the spring element S with the cylinder 1 and the housing 5 is prevented, the cylinder 1 and the housing 5 can be protected, and the rod guide (blocking member) 8 and the first free piston 7 It is possible to smoothly move in the axial direction with respect to the cylinder 1 and the housing 5 over a long period of time.

  In the damper D3 of the present embodiment, the rod element (blocking member) 8 and the first free piston 7 are separated from the rod guide (blocking member) 8 in the state where the spring element S is maximally separated in the axial direction. An initial load is applied to the free piston 7. In the damper D3 configured as described above, since the inside of the reservoir R is constantly pressurized, the hydraulic oil can be sufficiently supplied from the reservoir R into the pressure side chamber R2 that expands when the damper D3 extends, and the pressure in the cylinder 1 can be reduced. Poor suction of hydraulic oil is less likely to occur. Therefore, even when the damper D3 performs the contraction operation after the extension operation, the pressure in the cylinder 1 is rapidly increased, so that the damper D3 can exhibit the pressure-side damping force with good responsiveness, and the occurrence of "running" can be reduced. It can be suppressed.

  Furthermore, in the damper D3 of the present embodiment, the surface hardness of the sliding surface of the first free piston 7 that slides on the cylinder 1 and the housing 5 is determined by the surface hardness of the sliding surface of the first free piston 7 on which the cylinder 1 and the housing 5 slide. Softer than surface hardness. According to the damper D3 configured as described above, the first free piston 7 is easily slid with respect to the cylinder 1 and the housing 5, and a smooth expansion and contraction operation is also realized.

  Although not shown, instead of the configuration of the damper D3 shown in FIG. 3, one end of the outer cylinder 4 and the housing 5 is fitted to the rod guide 8 to close the open ends thereof, thereby forming the air chamber G. The housing 5 may be fitted to the valve case 9 so as to close the open ends of the housing 5 and the cylinder 1. Even with the damper configured as described above, the same function and effect as the damper D3 can be exerted.

  In the dampers D1, D2, and D3 of the present embodiment, the spring element S is a coil spring. Instead of this, the first free piston 7 is urged by the pressure of the gas sealed in the air chamber G. The spring element S may be an air spring or a combination of a coil spring and an air spring. Further, the spring element S may be formed of an elastic body such as rubber instead of the coil spring.

  Note that, as described above, the dampers D1, D2, and D3 are configured as uniflow-type dampers in which hydraulic oil circulates in the order of the reservoir R, the compression-side chamber R2, and the expansion-side chamber R1 during expansion and contraction operations. It may be a damper. In the case of a biflow damper, for example, the rectifying passage 2a is abolished and the expansion-side passage that gives resistance to the flow of the hydraulic oil from the expansion-side chamber R1 to the compression-side chamber R2 and the hydraulic oil from the compression-side chamber R2 to the expansion-side chamber R1 The piston 2 is provided with a pressure side passage which gives resistance to the flow, and the damping passage DP of the rod guide 8 is eliminated, and the valve case 9 is provided with a damping passage which gives resistance to the flow of hydraulic oil from the pressure side chamber R2 toward the reservoir R. I just need. The configuration of the biflow damper described above is merely an example, and may be another configuration. The structure of the present invention in which the reservoir R functions as an accumulator is applicable to various dampers.

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

DESCRIPTION OF SYMBOLS 1 ... cylinder, 2 ... piston, 3 ... rod, 4 ... outer cylinder, 5 ... housing, 6 ... closing member (second free piston), 6e, 8f ... Closing member side aligning portion, 7 ... First free piston, 7e ... First free piston side aligning portion, 8 ... Rod guide (closing member), 8a ... Cylinder fitting portion, 8b ... outer cylinder fitting part, 8e ... housing fitting part, D1, D2, D3 ... damper, G ... air chamber, R ... reservoir, R1 ... extension side chamber, R2 ... ..Compression side chamber, S ... spring element

Claims (6)

A cylinder,
A piston slidably inserted into the cylinder to partition the cylinder into an extension chamber and a compression chamber;
A rod inserted into the cylinder and connected to the piston;
An outer cylinder disposed radially outside the cylinder to form a reservoir that covers the cylinder and communicates with the cylinder between the cylinder and the outer cylinder;
A cylindrical housing housed in a reservoir between the cylinder and the outer cylinder;
A closing member that closes between the cylinder and any one of the outer cylinders and the housing;
An annular, slidably contacting both the one of the cylinder and the outer cylinder and the housing and being axially movable with respect to the two, and the one of the cylinder and the outer cylinder and the housing; A first free piston that defines an air chamber between and between the closing member,
A spring element for urging the first free piston in a direction to enlarge the air chamber. The closing member is a ring-shaped second free piston which is slidably in contact with both the one of the cylinder and the outer cylinder and the housing and is axially movable with respect to the two. The damper according to claim 1. The closing member,
A cylinder fitting portion formed by a step portion and fitted with the cylinder,
A housing fitting portion formed by a step portion and fitted with the housing;
An outer cylinder fitting portion formed by a step portion and fitted with the outer cylinder,
The damper according to claim 1, wherein: The spring element is a coil spring,
The closing member is fitted to one end of the coil spring to position a radial position of one end of the coil spring at a position separated from both the one of the cylinder and the outer cylinder and the housing. It has a side alignment part,
The first free piston is fitted to the other end of the coil spring so that a radial position of the other end of the coil spring is located at a position separated from both the one of the cylinder and the outer cylinder and the housing. The damper according to any one of claims 1 to 3, further comprising a first free piston-side centering portion for positioning. The spring element applies an initial load to the closing member and the first free piston in a state where the closing member and the first free piston are maximally separated in the axial direction. The damper according to any one of claims 1 to 4. The surface hardness of a sliding surface of the first free piston that slides on the one of the cylinder and the outer cylinder and the housing is such that the one of the cylinder and the outer cylinder slides on the first free piston of the housing. The damper according to claim 1, wherein the damper has a surface hardness smaller than that of the sliding surface.

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