JP4750593B2 - Shock absorber - Google Patents

Description

  The present invention relates to an improved shock absorber.

  Conventionally, in this type of shock absorber, generally, a piston portion is provided with a damping force generation element. As this damping force generation element, for example, an annular end is provided at an outlet end of a port provided in the piston portion. It is known that a leaf valve is stacked and a port is opened and closed with this leaf valve.

  In particular, in a shock absorber equipped with a damping force generating element that opens and closes a port with a leaf valve by fixing and supporting the inner peripheral side of the leaf valve and bending the outer peripheral side, the damping force is large in the medium to high speed region. In order to solve this problem, there is a case where the ride comfort in the vehicle becomes too bad. To eliminate this, as shown in FIG. 7, the inner periphery of the leaf valve L is not fixedly supported, and the inner periphery of the leaf valve L is fixed to the piston rod. A damping force generating element is provided which is slidably brought into contact with the outer periphery of a cylindrical piston nut N or the like which is screwed to R to fix the piston P, and the back surface of the leaf valve L is urged by a coil spring S through a valve restraining member M. A shock absorber has been proposed (see, for example, Patent Documents 1 and 2).

In the shock absorber having such a damping force generating element, the outer peripheral side of the leaf valve L is stacked on the leaf valve L when the piston speed when the piston P moves upward is in the low speed region as shown in the figure. Since it bends with the contact part of the valve restraining member M as a fulcrum, it exhibits the same damping characteristics as the valve structure in which the inner periphery is fixedly supported, and passes through the port Po when the piston speed reaches the middle-high speed region. The pressure of the hydraulic oil acting on the leaf valve L acts against the biasing force of the coil spring S, and the leaf valve L lifts and retreats in the axial direction from the piston P together with the valve restraining member M, so that the inner periphery is fixed. Compared to the valve structure of the shock absorber to be supported, the flow path area is increased, and as shown in FIG. 8, it is possible to suppress the damping force from becoming excessive and to improve the riding comfort in the vehicle.
JP-A-9-291196 (FIG. 1) Japanese Patent Laying-Open No. 2005-330975 (FIG. 1)

  However, in the proposed shock absorber as described above, although it is a useful technique in that the ride comfort in the vehicle can be improved, it may be pointed out that there are the following problems.

  This is because, for example, when the piston speed when the piston P moves upward reaches the high speed region, in the conventional shock absorber, the leaf valve L moves backward from the piston P in the axial direction according to the piston speed and lifts. The attenuation coefficient does not increase.

  Therefore, when the piston speed reaches the high speed region, the damping force is insufficient, and the vibration is not sufficiently suppressed, so that the riding comfort in the vehicle is deteriorated.

  Therefore, the present invention was devised to improve the above problems, and the object of the present invention is to improve the riding comfort in the vehicle even when the piston speed reaches the high speed region. Is to provide a shock absorber.

In order to achieve the above object, the means of the present invention includes a cylinder, a head member that closes the end of the cylinder, and two slidably inserted into the cylinder while being pivotally supported by the head member . A piston separating the pressure chambers, a piston rod connected to the piston and movably inserted into the cylinder, a passage communicating the two pressure chambers provided in the piston, and at least provided in the middle of the passage In a shock absorber having a damping force generating element that provides resistance to a flow from one pressure chamber to the other pressure chamber, and a reservoir that communicates with the other pressure chamber, a bypass passage that communicates one pressure chamber with the reservoir the provided a valve element provided in the middle of the bypass passage, the valve element, the bypass passage side to be communicated with the reservoir while opening the surface facing the one of the pressure chambers of the head member A valve body, a valve body slidably received in the recess, and a biasing means for biasing the valve body in a direction protruding from the recess. An annular groove provided on the outer periphery of the main body and a hole for communicating the annular groove with one of the pressure chambers. When the piston speed is in the low speed and high speed range, the outer periphery of the valve body is opened from the side of the recess The communication between the pressure chamber and the reservoir is blocked by facing the bypass passage, and the annular groove is made to face the bypass passage opened from the side of the recess when the piston speed is in the medium speed region. One pressure chamber and the reservoir are communicated with each other.
In this case, the passage is composed of a first passage that allows a flow from one pressure chamber to the other pressure chamber and a second passage that allows a flow from the other pressure chamber to the one pressure chamber. The generating element is preferably provided only in the first passage.
Similarly, an outer cylinder that covers the cylinder and a head member that closes the cylinder and the end of the outer cylinder and supports the piston rod are provided, and a gap between the cylinder and the outer cylinder is used as a reservoir and bypassed to the head member. A passage may be formed and the valve element may be provided in the head member.
Similarly, a socket-shaped cylinder is raised above the top outer periphery of the valve body, and a spring is interposed between the top of the valve body and the upper end of the recess, and this spring biases the valve body in a direction that protrudes from the recess. It is preferable.
Similarly, the recess is an annular recess that opens from the outer peripheral side of the piston rod of the head member and faces one pressure chamber, and the valve body is preferably formed in an annular shape.
Furthermore, a check valve that allows a flow from one pressure chamber to the reservoir, but prevents a flow from the reservoir to the one pressure chamber, may be provided in the middle of the bypass passage.

  According to the shock absorber of the present invention, when the piston speed is in the medium speed region, the damping force does not become too large to deteriorate the riding comfort of the vehicle. The damping coefficient can be increased, and even when the piston speed reaches the high speed region, the damping force is not insufficient, vibration is sufficiently suppressed, and riding comfort in the vehicle can be improved.

  Furthermore, under conditions where the shock absorber amplitude is large and the piston speed reaches the high speed region, the damping coefficient can be increased to increase the damping force generated by the shock absorber. It can be quickly reduced, and the impact at the time of maximum extension or compression can be alleviated.

  Hereinafter, the shock absorber of the present invention will be described with reference to the drawings. FIG. 1 is a longitudinal sectional view of a shock absorber according to an embodiment. FIG. 2 is an enlarged longitudinal sectional view of the valve element of the shock absorber in one embodiment. FIG. 3 is an enlarged vertical cross-sectional view of the shock absorber according to the embodiment in a state where a valve element is opened. FIG. 4 is an enlarged longitudinal sectional view of the valve element of the shock absorber in one embodiment when the piston speed is in the high speed region. FIG. 5 is a diagram showing damping characteristics in a shock absorber in which the valve structure of the shock absorber of the present invention is embodied. FIG. 6 is an enlarged longitudinal sectional view of a valve element of a shock absorber according to a modification of the embodiment.

  As shown in FIG. 1, the shock absorber in one embodiment includes a cylinder 1, a piston 2 that is slidably inserted into the cylinder 1 and that separates two pressure chambers R <b> 1 and R <b> 2 into the cylinder 1, and a piston 2, a piston rod 3 that is movably inserted into the cylinder 1, a first passage 2a and a second passage 2b that communicate with the two pressure chambers provided in the piston 2, and a first passage 2a. A laminated leaf valve 4 that is a damping force generating element provided in the middle of this, a reservoir R that communicates with the other pressure chamber R2, a bypass passage B that communicates one pressure chamber R1 to the reservoir R, The valve element 10 provided in the middle is provided.

  In the following, the cylinder 1 is formed in a cylindrical shape, and the upper and lower ends thereof are respectively closed by a head member 5 and a bottom member 6 as cylinder end portions. A is separated, and the working chamber A is partitioned into one pressure chamber R1 and the other pressure chamber R2 by a piston 2 that is slidably inserted into the cylinder 1, and is filled with hydraulic oil. Has been.

  Further, an outer cylinder 7 that covers the cylinder 1 is disposed outside the cylinder 1. The upper and lower ends of the outer cylinder 7 are closed by the head member 5 and the bottom member 6, respectively. A sealed state is established, and a gap between the cylinder 1 and the outer cylinder 7 is a reservoir R. The reservoir R is filled with hydraulic oil and gas. As shown in FIGS. 1 and 2, the head member 5 is inserted into the outer cylinder 7 while inserting the lower step portion 5 c having the smallest diameter into the cylinder 1, and the seal member S is disposed above the head member 5. The head member 5 is fixed to the cylinder 1 and the outer cylinder 7 by caulking the upper end portion of the outer cylinder 7 together with the seal member S, and the cylinder 1 and the outer cylinder 7 are positioned concentrically by the head member 5. It has become. Further, the lower end of the outer cylinder 7 in FIG. 1 is closed by a cap C, and the outer cylinder 7 is sealed by a seal member S and a cap C arranged on the upper end side.

  The laminated leaf valve 4 as a damping force generating element is laminated at the lower end in FIG. 1 of the piston 2, closes the lower end of the first passage 2 a provided in the piston 2, and the second passage provided in the piston 2. The upper end of 2b is closed by a check valve 8.

  Therefore, when the shock absorber extends and the piston 2 moves upward relative to the cylinder 1, the hydraulic oil in one pressure chamber R1 is closed at the upper end of the second passage 2b by the check valve 8. Therefore, the laminated leaf valve 4 closing the lower end of the first passage 2a is bent downward, passes through the first passage 2a, and moves into the other pressure chamber R2.

  On the other hand, when the shock absorber is compressed and the piston 2 moves downward relative to the cylinder 1, the lower end of the first passage 2 a is closed by the laminated leaf valve 4 for the hydraulic oil in the other pressure chamber R 2. Therefore, the check valve 8 that closes the upper end of the second passage 2b is bent upward, passes through the second passage 2b, and moves into one pressure chamber R1.

  When the shock absorber extends, the laminated leaf valve 4 gives a predetermined resistance to the flow of the hydraulic oil, causing a difference in pressure between the pressure chambers R1 and R2, and the shock absorber exerts a damping force. It can be generated. On the other hand, when the shock absorber is compressed, the pressures in the pressure chambers R1 and R2 are maintained at substantially the same pressure, and the pressure difference between the reservoir R and the other pressure chamber R2, which will be described later. Thus, the shock absorber can generate a damping force.

  In other words, the first passage 2a only allows the flow of hydraulic oil from one pressure chamber R1 to the other pressure chamber R2, and the other second passage 2b extends from the other pressure chamber R2 to one pressure chamber. Only the flow of hydraulic oil toward R1 is allowed, and the laminated leaf valve 4 that is a damping force generation element provides resistance only to the flow of hydraulic oil from one pressure chamber R1 to the other pressure chamber R2. It has become.

  Further, when the piston 2 moves in the cylinder 1, the piston rod 3 enters and exits the cylinder 1, but the hydraulic oil corresponding to the volume of the piston rod 3 entering and exiting the cylinder 1 is excessive and insufficient in the working chamber A. However, the excess or deficient hydraulic oil is supplied or discharged from the reservoir R through the flow paths 6 a and 6 b provided in the bottom member 6.

  More specifically, the bottom member 6 is provided with flow paths 6a and 6b communicating the other pressure chamber R2 and the reservoir R. The lower end of the flow path 6a in FIG. The upper end in FIG. 1 of the path 6b is closed by a check valve 6d.

  Accordingly, when the hydraulic oil corresponding to the volume of the piston rod 3 entering the cylinder 1 is compressed in the working chamber A due to the compression of the shock absorber, the working oil in the other pressure chamber R2 passes through the flow path 6a. It is discharged to the reservoir R. When the hydraulic oil passes through the flow path 6a, the leaf valve 6c acts as a resistance to the flow to increase the pressure in the other pressure chamber R2, and the shock absorber reduces the damping force during compression. The situation that cannot be generated is avoided. On the other hand, when the shock absorber expands and hydraulic oil corresponding to the volume of the piston rod 3 that retreats from the cylinder 1 becomes insufficient in the working chamber A, the working oil in the reservoir R passes through the flow path 6b. It is supplied to the reservoir R. When the hydraulic oil passes through the flow path 6b, the check valve 6d gives little resistance to the flow.

  Next, as shown in FIGS. 1 and 2, the head member 5 has a shape having two step portions on the outer peripheral side, and a piston rod 3 is inserted into the center portion so that the piston rod 3 can be inserted therethrough. A rod insertion hole 5a is provided, and the piston rod 3 is slidably supported by the piston rod insertion hole 5a.

  The lower step portion 5c having the smallest diameter is fitted into the cylinder 1, and the head member 5 is provided with a concave portion 11 having a circular cross section that opens from a surface facing the one pressure chamber R1 of the lower step portion 5c. Yes. Further, the side portion 11a of the concave portion 11 communicates with a bypass passage B opened from the lower end of the middle step portion 5d of the head member 5 facing the reservoir R, and the bypass passage B is connected to one pressure chamber R1 via the concave portion 11. And the reservoir R are communicated with each other.

  Further, an annular check valve 9 is sandwiched between the upper end in FIG. 1 of the cylinder 1 and the lower end of the middle step portion 5d of the head member 5, and this check valve 9 is connected to the outlet end of the bypass passage B. Is closed to allow the flow of hydraulic oil from one pressure chamber R1 to the reservoir R, but conversely to prevent the flow of hydraulic oil from the reservoir R to the one pressure chamber R1.

  As the configuration of the check valve 9, it is possible to adopt a configuration other than that described above, but the check valve 9 sandwiches the annular plate between the end of the cylinder 1 and the head member 5 as described above. With this configuration, the structure of the check valve 9 is greatly simplified, the volume of the reservoir R is not compressed, and problems such as increasing the overall length of the shock absorber are avoided.

  Subsequently, the valve element 10 includes the concave portion 11, a valve body 12 that is slidably accommodated in the concave portion 11, and a spring 13 that is a biasing means that biases the valve body 12 in a direction protruding from the concave portion 11. It is configured.

  Specifically, as shown in FIG. 2, the valve body 12 includes a valve body 12a formed in a cylindrical shape whose top is closed, an annular groove 12b provided on the outer periphery of the valve body 12a, and an annular groove 12b. 2 is provided with a hole 12c communicating with the pressure chamber R1, and a socket-shaped cylindrical portion 12d rises above the outer periphery of the top of the valve body 12a in FIG. 2, and the top of the valve body 12a and the upper end of the recess 11 The valve body 12 is urged in a direction protruding from the recess 11 by a spring 13 interposed therebetween. The outer peripheral surface of the valve body 12a is in sliding contact with the side portion 11a of the recess 11 except for the annular groove 12b, and the recess of the valve body 12 is provided by a snap ring 11b installed near the lower end of the side portion 11a of the recess 11. 11 is prevented from falling out. Further, the cylindrical portion 12d prevents the spring 13 interposed between the top of the valve main body 12a and the upper end of the concave portion 11 from being eccentric with respect to the valve main body 12a, and the valve main body 12a slides smoothly into the concave portion 11. It is possible.

  Further, an annular groove 12b provided on the outer periphery of the valve body 12a and an inner side facing the one pressure chamber R1 of the valve body 12a are communicated with each other through a hole 12c. The pressure chamber R1 and the reservoir R are communicated only when facing the outlet end of the bypass passage B communicated with the portion 11a.

  As shown in FIG. 2, when the piston speed when the shock absorber is extended is in the low speed region, the valve element 10 has a bypass passage that opens the outer periphery of the valve body 12a from the side portion 11a of the recess 11. As shown in FIG. 3, when the piston speed is increased and exceeds the low speed and is in the middle speed region, the communication between the pressure chamber R1 and the reservoir R is set to be opposed to B. The one pressure chamber R1 and the reservoir R are communicated with each other so that the annular groove 12b faces the bypass path B opened from the side portion 11a of the recess 11.

  That is, when the piston speed is in the middle speed region, the pressure in one pressure chamber R1 causes the valve body 12a to be pushed in the direction toward the back of the recess 11 against the urging force of the spring 13, and the annular groove 12b. Is opposed to the bypass path B, whereby the one pressure chamber R1 and the reservoir R communicate with each other.

  When the shock absorber is suddenly compressed when the valve element 10 is in the open state in this way, the pressure in one pressure chamber R1 may suddenly decrease, but in such a case In this case, the check valve 9 is quickly closed, and a situation in which gas is mixed into the reservoir R into one pressure chamber R1 is prevented.

  Furthermore, when the piston speed exceeds the medium speed and is in the high speed region, the valve body 12a moves further into the recess 11 as shown in FIG. By moving to the rear side, the bypass path B is blocked and the communication between the one pressure chamber R1 and the reservoir R is cut off.

  Conversely, when the shock absorber is compressed, the pressure in the one pressure chamber R1 and the other pressure chamber R2 are substantially the same as described above, and the reservoir R is provided by the leaf valve 6c provided in the flow path 6a. Since the pressure in each of the pressure chambers R1 and R2 is maintained higher than the internal pressure, when the piston speed is in the middle speed region, the valve element 10 is increased by the increase in the pressure in one pressure chamber R1. Will open, and the valve element 10 will close when the piston speed is low or in the high speed region.

  That is, the valve element 10 is closed when the piston speed when the shock absorber is expanded and contracted is in the low speed and high speed areas, and is opened only when the piston speed is in the medium speed area.

  The piston speed at which the valve element 10 opens and closes on the expansion side and the compression side of the shock absorber may be set to be the same or different. In other words, it can be set arbitrarily according to the damping characteristics (damping force with respect to the piston speed) required during expansion and compression of the shock absorber, and the standard of low, medium, and high speed piston speeds on the expansion side and compression side. May be different. The piston speeds are classified into low speed, medium speed, and high speed, which are standards for the timing of each switching operation in which the valve element 10 opens from the closed state and then closes again. Can be set arbitrarily so as to satisfy the attenuation characteristics as shown in FIG. 5 to be described later.

  Therefore, in this shock absorber, when the piston speed when the shock absorber is extended is in the middle speed region, the hydraulic oil in one pressure chamber R1 passes through the first passage 2a provided in the piston 2. In addition to moving into the other pressure chamber R2, the valve element 10 opens and moves into the reservoir R via the bypass B. On the other hand, when the piston speed is in the low speed region or in the high speed region, the valve element 10 remains closed as described above, so that the hydraulic oil in one pressure chamber R1 passes only through the first passage 2a. Through the other pressure chamber R2.

  On the contrary, when the piston speed at the time of compression of the shock absorber is in the middle speed region, the hydraulic oil in the other pressure chamber R2 passes through the second passage 2b provided in the piston 2 and is one pressure chamber. While moving into R1, the volume of hydraulic oil that enters the cylinder 1 of the piston rod 3 moves to the reservoir R through the flow path 6a, but the inside of one pressure chamber R1 and the other pressure chamber R2 Since the pressure in the pressure chambers R1 and R2 is maintained higher than the pressure in the reservoir R by the leaf valve 6c, the valve element 10 opens and moves into the reservoir R via the bypass passage B. Will come to do. On the other hand, when the piston speed is in the low speed region or in the high speed region, the valve element 10 remains closed as described above, so that the hydraulic oil in the working chamber A is stored in the reservoir only through the flow path 6a. Move into R.

  Then, when the piston speed when the shock absorber is extended is in the low speed region, the shock absorber generates a damping force only by the laminated leaf valve 4 that closes the end of the first passage 2a until the valve element 10 is opened. Therefore, as shown in FIG. 5, the damping characteristic (damping force with respect to the piston speed) has a relatively large damping coefficient (a value obtained by dividing the damping force by the piston speed), and the piston speed is within the middle speed range. When the valve element 10 is open, the pressure increase in the one pressure chamber R1 with respect to the increase in the piston speed is suppressed more than when the piston speed is in the low speed region, so that the damping coefficient is compared with that in the low speed region. And the inclination becomes smaller. Further, when the piston speed increases and reaches the high speed region, the valve element 10 is closed again, and the pressure increase in one pressure chamber R1 with respect to the increase in the piston speed is larger than when the piston speed is in the medium speed region. Therefore, the damping coefficient is larger than that in the medium speed region, and the slope of the damping characteristic is increased.

  Conversely, when the piston speed during compression of the shock absorber is in the low speed region, the shock absorber is only in the pressure chambers R1, R2 and the reservoir R by the leaf valve 6c of the flow path 6a until the valve element 10 is opened. As shown in FIG. 5, the damping coefficient (change rate of damping force with respect to the piston speed) is relatively large and has a large slope. Is in the medium speed region, the valve element 10 is opened, and an increase in the differential pressure between the pressure chambers R1, R2 and the reservoir R with respect to the increase in the piston speed is suppressed compared to when the piston speed is in the low speed region. Therefore, the attenuation coefficient is smaller than that in the low speed region, and the inclination is small. Further, when the piston speed increases and reaches the high speed region, the valve element 10 is closed again, and the pressure chambers R1, R2 and the reservoir R for the increase in the piston speed than when the piston speed is in the medium speed region, The increase in the differential pressure becomes larger, the damping coefficient becomes larger than that in the medium speed region, and the slope of the damping characteristic becomes larger.

  Therefore, in the shock absorber according to the present embodiment, when the piston speed is in the medium speed region, the damping force does not become too large to deteriorate the riding comfort of the vehicle, and the piston speed is high. When reaching the region, the damping coefficient can be increased, and even when the piston speed reaches the high speed region, the damping force is not insufficient, vibration is sufficiently suppressed, and the riding comfort in the vehicle is improved. be able to. In the present embodiment, the above effect can be obtained both when the shock absorber is expanded and when it is compressed.

  Furthermore, in a situation where the amplitude at which the shock absorber is fully extended and the piston speed reaches the high speed region, the damping coefficient can be increased to increase the damping force generated by the shock absorber. Therefore, the piston speed can be quickly reduced, and the impact at the maximum extension can be reduced. In this embodiment, even when the shock absorber is at the maximum compression, the damping coefficient can be increased to increase the generated damping force of the shock absorber, so that the piston speed can be quickly reduced and the maximum compression is achieved. The impact of time can be reduced.

  Then, only by adding the valve element 10 and the bypass passage B to the shock absorber, the damping characteristics on both the expansion side and the pressure side of the shock absorber can be made suitable for the vehicle. In other words, when a special valve or spring is incorporated in the piston section to exhibit the damping characteristics on the expansion side and the compression side, a special mechanism must be provided on both sides of the piston. It is very advantageous that the damping characteristic can be realized by controlling both damping characteristics by only adding the valve element 10.

  Further, since the valve element 10 is provided on the head member 5, the stroke length of the shock absorber (in comparison with a case where a special valve or spring is incorporated in the piston portion to exhibit the damping characteristics on the expansion side and the compression side) This is advantageous in that it does not affect the stretchable range length). That is, when a special mechanism is provided at one end or both ends of the piston portion, the piston portion may be elongated in the axial direction of the shock absorber (the vertical direction in FIG. 1), thereby shortening the stroke length. Alternatively, if the stroke length is maintained, the shock absorber may become long. However, in the present embodiment, since the valve element 10 and the bypass path B are provided in the head member 5, the above-described problems are caused. There is no.

  The piston speed at the boundary where the valve element 10 changes from the closed state to the open state, that is, the piston speed at the boundary between the low speed region and the medium speed region and the boundary between the medium speed region and the high speed region is the pressure received by the valve body 12a. Although it can be arbitrarily determined by the area, the spring constant of the spring 13 as the biasing means, and the communication position to the side portion 11a of the recess 11 of the bypass B, the boundary between the medium speed region and the high speed region can be determined. If the piston speed is within the range of 1 m / s or more and 2 m / s or less, the damping coefficient can be kept relatively small when the piston speed is in the medium speed region, so that the damping force is large. The ride comfort in the vehicle can be ensured without becoming too much, making it suitable for an actual vehicle to which the shock absorber is applied, and improving the practicality of the shock absorber.

  In addition, in the place mentioned above, although the recessed part 11 is formed as a mere hole, this is formed in the outer peripheral side of the piston rod 3 like the shock absorber in the modification of one Embodiment shown in FIG. A coil spring that is formed as an annular recess 21 that opens from the surface facing the one pressure chamber R1 of the lower step portion 5c, and that the valve main body 22 accommodated in the annular recess 21 is also annular, and is also accommodated in the annular recess 21 in the urging means. 23 may be used. Even in this case, if the annular groove 22a is provided on the outer periphery of the valve main body 22 and the hole 22b communicated with the annular groove 22 is provided, the piston speed is medium as in the case of the valve element 10 described above. When in the region, the one pressure chamber R1 and the reservoir R can be communicated with each other, and the same operational effects as the shock absorber in the above-described embodiment can be obtained. In this case, the pressure receiving area of the valve body 22 can be increased, and the opening area of the annular recess 21 can be increased, which is advantageous in that the flow rate can be secured.

  Further, in the above description, the damping force generation element is provided only in the first passage 2a. However, in the case where the damping force generation element is provided also on the second passage 2b side, the pressure in the one pressure chamber R1 and the other pressure are provided. Since a large difference occurs in the pressure in the chamber R2, it becomes impossible to control the damping characteristic when the shock absorber is compressed by the valve element 10 and the bypass B, but the damping characteristic when the shock absorber is extended is shown in FIG. 5 can be controlled in the same way as shown in FIG. 5, so that when the damping characteristics during compression do not need to be as shown in FIG. 5, both the passages 2a and 2b provided in the piston 1 are attenuated. Of course, a force generating element may be provided, and the effect of the present invention is not lost.

  Moreover, although the constituent member of the urging means is a spring, it is sufficient to apply a predetermined urging force to the valve bodies 12a and 22, so this may be, for example, a disc spring or a leaf spring, or an elastic body such as rubber. Or you may.

  Although the description of the embodiment of the shock absorber according to the present invention has been described above, the scope of the present invention is not limited to the details shown or described.

It is a longitudinal cross-sectional view of the shock absorber in one embodiment. It is an expanded longitudinal cross-sectional view of the valve element of the shock absorber in one embodiment. It is an expanded vertical sectional view in the state where the valve element of the shock absorber in one embodiment opened. It is an expanded longitudinal cross-sectional view of the valve element of the shock absorber in one embodiment when the piston speed is in the high speed region. It is a figure which shows the damping characteristic in the buffer which embodied the valve | bulb structure of the buffer of this invention. It is an expansion longitudinal cross-sectional view of the valve element of the shock absorber in the modification of one Embodiment. It is a longitudinal cross-sectional view of the piston part of the buffer which actualized the valve structure of the conventional buffer. It is a figure which shows the damping characteristic in the buffer which actualized the valve structure of the conventional buffer.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cylinder 2 Piston 2a 1st channel | path 2b 2nd channel | path 3 Piston rod 4 Laminated leaf valve 5 which is a damping force generation element Head member 5a Piston rod insertion hole 5c Lower stage part 5d Middle stage part 6 Bottom member 6a, 6b Flow path 6c Leaf valve 6d , 8 Check valve 7 Outer cylinder 9 Check valve 10 Valve element 11 Concave portion 11a Concave side portion 11b Snap ring 12 Valve body 12a, 22 Valve body 12b, 22a Annular groove 12c, 22b Hole 12b Cylindrical portion 13 Spring as biasing means 21 Circular groove 23 Coil spring A serving as an urging means Working chamber B Bypass path C Cap R Reservoir R1 One pressure chamber R2 The other pressure chamber S Seal member

Claims (6)

A cylinder, a head member that closes the end of the cylinder, a piston that is slidably inserted into the cylinder while being axially supported by the head member, and that separates the two pressure chambers in the cylinder; A piston rod that is movably inserted into the cylinder, a passage that communicates the two pressure chambers provided in the piston, and a flow that is provided in the middle of the passage from at least one pressure chamber to the other pressure chamber. In a shock absorber provided with a damping force generating element that gives a pressure and a reservoir that communicates with the other pressure chamber, a bypass path that communicates one pressure chamber with the reservoir is provided, and a valve element is provided in the middle of the bypass path, The valve element opens from the surface facing the one pressure chamber of the head member, and a bypass passage communicating with the reservoir is opened from the side, and is slidable in the recess. And a biasing means for biasing the valve body in a direction protruding from the recess. The valve body includes a valve body, an annular groove provided on an outer periphery of the valve body, and an annular groove. The pressure chamber is provided with a hole communicating with the pressure chamber, and when the piston speed is in the low speed and high speed regions, the outer periphery of the valve body faces the bypass passage opened from the side of the recess, and the one pressure chamber and the reservoir And the pressure chamber and the reservoir are communicated with each other so that the annular groove faces the bypass passage opened from the side of the recess when the piston speed is in the medium speed region. Shock absorber. The passage includes a first passage that allows a flow from one pressure chamber to the other pressure chamber and a second passage that allows a flow from the other pressure chamber to the one pressure chamber. The shock absorber according to claim 1, wherein the shock absorber is provided only in the first passage. An outer cylinder that covers the cylinder, a head member that closes the ends of the cylinder and the outer cylinder, and that supports the piston rod are provided. The gap between the cylinder and the outer cylinder serves as a reservoir, and a bypass path is provided to the head member. 3. A shock absorber according to claim 1, wherein the shock absorber is formed and a valve element is provided in the head member. The valve element is opened from a surface facing the one pressure chamber of the head member and has a recess in which a bypass passage communicating with the reservoir is opened from the side, a valve body slidably accommodated in the recess, a valve The valve body includes a valve body, an annular groove provided on the outer periphery of the valve body, and a hole communicating with the annular groove and one pressure chamber. And, when the piston speed is in the low speed and high speed regions, the outer periphery of the valve body is opposed to the bypass passage opened from the side of the recess to block communication between one pressure chamber and the reservoir, 4. The buffer according to claim 3, wherein when the piston speed is in a medium speed region, the pressure groove and the reservoir are communicated with each other so that the annular groove faces a bypass passage opened from the side of the recess. vessel. 5. The buffer according to claim 4, wherein the recess is an annular recess that opens from a surface facing the one pressure chamber on the outer peripheral side of the piston rod of the head member, and the valve body is formed in an annular shape. vessel. Although permits flow towards the middle of the bypass passage from the one pressure chamber to the reservoir any one of claims 1, characterized in that a check valve that prevents flow toward the one pressure chamber from the reservoir of 5 1 The shock absorber described in the paragraph .

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