JP2012057746A - Shock absorber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a shock absorber capable of improving ride comfort in a vehicle by reducing damping force even when a piston speed is high, and to also provide the shock absorber capable of separately setting the damping force in extension operation and contraction operation.SOLUTION: In the shock absorber having a first passage 3 and a second passage 4 for communicating two operation chambers R1 and R2 arranged in a cylinder, a pressure chamber C arranged in the middle of the second passage 4, a free piston 9 movably inserted into the pressure chamber C and a spring element 10 for generating energizing force for restraining displacement to the pressure chamber C of the free piston 9, and the shock absorber is provided with a one side port 11 and the other side port 12 for communicating the two operation chambers R1 and R2, a one side relief valve 13 for opening-closing the one side port 11 and the other side relief valve 14 for opening-closing the other side port 12.

Description

  The present invention relates to an improvement of a shock absorber.

  Conventionally, in this type of shock absorber, a cylinder, a piston that is slidably inserted into the cylinder and divides the inside of the cylinder into an upper chamber and a lower chamber, and an upper chamber and a lower chamber provided in the piston communicate with each other. A first passage that opens from the tip of the piston rod to the side, a second passage that connects the upper chamber and the lower chamber, and a pressure chamber that is connected in the middle of the second passage and is attached to the tip of the piston rod And a free piston that is slidably inserted into the pressure chamber and divides the pressure chamber into one chamber and the other chamber, and a coil spring that biases the free piston. That is, one chamber in the pressure chamber communicates with the lower chamber through the second passage, and the other chamber in the pressure chamber communicates with the upper chamber through the second passage.

  In the shock absorber configured as described above, the pressure chamber is divided into one chamber and the other chamber by a free piston, and the upper chamber and the lower chamber are not directly communicated with each other via the second passage. However, when the free piston moves, the volume ratio between the one chamber and the other chamber changes, and the liquid in the pressure chamber enters and exits the upper and lower chambers according to the amount of movement of the free piston. And behave as if they were communicated through the second passage.

さらに、上記式（１）で示された伝達関数中のラプラス演算子ｓにｊωを代入して、周波数伝達関数Ｇ（ｊω）の絶対値を求めると、以下の式（２）が得られる。

上記各式から理解できるように、この緩衝装置における流量Ｑに対する差圧Ｐの伝達関数の周波数特性は、図１６のボード線図に示したように、Ｆａ＝Ｋ／｛２・π・Ａ^２・（Ｃ１＋Ｃ２＋Ｃ３）｝とＦｂ＝Ｋ／｛２・π・Ａ^２・（Ｃ２＋Ｃ３）｝の２つの折れ点周波数を持ち、また、Ｆ＜Ｆａの領域においては、伝達ゲインは略Ｃ１となり、Ｆａ≦Ｆ≦Ｆｂの領域においてはＣ１からＣ１・（Ｃ２＋Ｃ３）／（Ｃ１＋Ｃ２＋Ｃ３）まで漸減するように変化して、Ｆ＞Ｆｂの領域においては一定となる。すなわち、流量Ｑに対する差圧Ｐの伝達関数の周波数特性は、低周波数域では伝達ゲインが大きくなり、高周波数域では伝達ゲインが小さくなる。 Here, the differential pressure between the upper chamber and the lower chamber during expansion and contraction of the shock absorber is P, the flow rate of the liquid flowing out from the upper chamber is Q, the differential pressure P and the flow rate Q1 of the liquid passing through the first passage are Is a relationship between the difference between the pressure difference P and the pressure P1, and the flow rate Q2 of the liquid flowing from the upper chamber into the other chamber of the pressure chamber. The coefficient is C2, the pressure in one chamber of the pressure chamber is P2, the coefficient that is the relationship between the pressure P2 and the flow rate Q2 of the liquid flowing out from the one chamber into the lower chamber is C3, and the pressure receiving area of the free piston When the area is A, the displacement of the free piston with respect to the pressure chamber is X, the spring constant of the coil spring is K, and the transfer function of the differential pressure P with respect to the flow rate Q is obtained, Equation (1) is obtained. In equation (1), s represents a Laplace operator.

Furthermore, substituting jω for the Laplace operator s in the transfer function shown in the above equation (1) to obtain the absolute value of the frequency transfer function G (jω) yields the following equation (2).

As can be understood from the above equations, the frequency characteristic of the transfer function of the differential pressure P with respect to the flow rate Q in this shock absorber is expressed as Fa = K / {2 · π · A ² as shown in the Bode diagram of FIG. (C1 + C2 + C3)} and Fb = K / {2 · π · A ² · (C2 + C3)}, and in the region of F <Fa, the transfer gain is approximately C1, and Fa ≦ In the region of F ≦ Fb, it changes so as to gradually decrease from C1 to C1 · (C2 + C3) / (C1 + C2 + C3), and becomes constant in the region of F> Fb. That is, in the frequency characteristic of the transfer function of the differential pressure P with respect to the flow rate Q, the transfer gain increases in the low frequency range, and the transfer gain decreases in the high frequency range.

  Therefore, in this shock absorber, as shown by the frequency damping force characteristic in FIG. 17 (damping force characteristic with respect to the vibration frequency of the shock absorber), a large damping force is generated for low frequency vibration input, Since a small damping force can be generated for high-frequency vibration input, a high damping force can be reliably generated when the input vibration frequency is low, such as when the vehicle is turning, and the vehicle In a scene where the input vibration frequency is high, such as passing through the unevenness, a low damping force can be reliably generated to improve the riding comfort in the vehicle (see, for example, Patent Documents 1 and 2).

JP 2006-336816 A JP 2007-78004 A

  As described above, the conventional shock absorber is useful in that it can improve the riding comfort in the vehicle, but has the following problems.

  This is because the above shock absorber is provided in the housing in order to obtain a good frequency damping force characteristic that generates a large damping force for low frequency vibrations and a small damping force for high frequency vibrations. The one chamber is communicated with the lower chamber through an orifice that forms part of the second flow path, and the piston moves at a very high speed, for example, when the vehicle passes over the road surface. The flow resistance in the orifice described above is much higher than the flow resistance in the first flow path, and the flow rate flowing through the first flow path is significantly greater than the flow rate flowing through the second flow path. May not be realized.

  Thus, in the conventional shock absorber, when the piston speed is high, the damping force remains high, and the effect of insulating the transmission of vibration from the axle side to the vehicle body side disappears. There is a risk that riding comfort will be impaired.

  Moreover, the magnitude | size of the damping force anticipated at the time of the expansion | extension operation | movement of a shock absorber and a contraction operation | movement may differ.

  Therefore, the present invention was devised to improve the above-mentioned problems, and the object is to reduce the damping force even when the piston speed is high, thereby improving the riding comfort in the vehicle. It is to provide a shock absorber that can be set, and in addition, to provide a shock absorber that can set damping force separately during an extension operation and a contraction operation.

  In order to solve the above-described object, the problem solving means in the present invention communicates a cylinder, a partition member slidably inserted into the cylinder and partitioning the cylinder into two working chambers, and the two working chambers. The first passage, the second passage, the damping valve provided in the first passage, the pressure chamber provided in the middle of the second passage, and the pressure chamber communicated with one working chamber. A shock absorber comprising: a free piston that is divided into one chamber that is connected to the other chamber and the other chamber that communicates with the other working chamber; and a spring element that generates a biasing force that suppresses displacement of the free piston with respect to the pressure chamber. One side port communicating with one working chamber, the other side port communicating similarly with the two working chambers, one side relief valve opening and closing one side port using the pressure of one working chamber as a pilot pressure, and the other operation Room Characterized by providing the other side relief valve for opening and closing the other side port pressure as a pilot pressure.

  According to the shock absorber of the present invention, the frequency damping force characteristic and the speed damping force characteristic (buffer) of the conventional shock absorber can be used even when the piston speed is high such that the vehicle passes through the unevenness of the road surface while traveling. (The characteristic of damping force with respect to the piston speed of the device) By reducing the gradient of the damping force with respect to the piston speed, the damping force can be reliably reduced, so that the damping force remains high as with conventional shock absorbers. Thus, the problem that the effect of insulating the transmission of vibration from the axle to the vehicle body can be eliminated, and the riding comfort in the vehicle can be improved.

  Also, when the shock absorber is contracted, only the one side relief valve is opened, and when the shock absorber is extended, only the other side relief valve is opened, so each speed damping force characteristic when the shock absorber is contracted and extended. Can be set independently, and the degree of tuning is greatly improved.

  Thus, since the gradient of the speed damping force characteristic in the contraction stroke of the shock absorber can be reduced, the effect of reducing the impact shock when the wheel rides on the road surface is increased, and the gradient of the speed damping force characteristic in the extension stroke is reduced. Therefore, it is possible to mitigate the impact generated when the submerged vehicle body is turned back, and the speed damping force characteristics can be freely set on both sides of the expansion and contraction. At times, the shock can be reduced while firmly supporting the vehicle body, and the vehicle can be provided with a supple but firm suspension.

It is a longitudinal cross-sectional view of the shock absorber in one embodiment. It is a Bode diagram which showed the gain characteristic of the frequency transfer function of the pressure to the flow rate. It is the figure which showed the frequency damping force characteristic of the shock absorber. It is a figure which shows the characteristic (frequency damping force characteristic) of the damping force which a buffer device generate | occur | produces with respect to a vibration frequency when a piston speed exists in a high-speed area and a buffer device expands and contracts. It is a figure which shows the characteristic (speed damping force characteristic) of the damping force generate | occur | produced with respect to the piston speed of a buffering device, when a buffering device vibrates with a certain vibration frequency. It is a partially expanded longitudinal cross-sectional view of a specific shock absorber. It is a figure which shows one modification of a valve disc. It is a figure which shows the other modification of a valve disc. FIG. 9 is an exploded plan view of the one-side relief valve shown in FIG. 8. It is a figure explaining the frequency damping force characteristic of a specific shock absorber. It is a partially expanded longitudinal cross-sectional view of one modified example of a specific shock absorber. It is a partially expanded longitudinal cross-sectional view of another modification of a specific shock absorber. It is a partially expanded longitudinal cross-sectional view of another example of a specific shock absorber. It is a partially expanded longitudinal cross-sectional view of another modification of another example of a specific shock absorber. It is a partially expanded longitudinal cross-sectional view of another modification of another example of a specific shock absorber. It is the Bode diagram which showed the gain characteristic of the frequency transfer function of the pressure with respect to the flow volume of the conventional shock absorber. It is the figure which showed the characteristic of the damping force with respect to the vibration frequency of the conventional shock absorber.

  Hereinafter, the present invention will be described with reference to the drawings. As shown in FIG. 1, a shock absorber D of the present invention includes a cylinder 1 and a partition wall that is slidably inserted into the cylinder 1 and divides the cylinder 1 into two working chambers R1 and lower chamber R2. In the middle of the piston 2 as a member, the first passage 3 and the second passage 4 communicating the upper chamber R1 and the lower chamber R2, the damping valve V provided in the first passage 3, and the second passage 4. The provided pressure chamber C, the one chamber 7 that is movably inserted into the pressure chamber C and communicates with the lower chamber R2 as one working chamber, and the upper chamber R1 as the other working chamber. A free piston 9 partitioned into the other chamber 8 communicated, a spring element 10 that generates a biasing force that suppresses displacement of the free piston 9 relative to the pressure chamber C, and a one-side port that communicates the upper chamber R1 and the lower chamber R2. 11 and the other port 1 communicating the upper chamber R1 and the lower chamber R2 in the same manner And a one-side relief valve 13 that opens and closes the one-side port 11 using the pressure in the lower chamber R2 as a pilot pressure, and a second-side relief valve 14 that opens and closes the other-side port 12 using the pressure in the upper chamber R1 as a pilot pressure. It is configured and is interposed between a vehicle body and an axle in a vehicle to generate a damping force and suppress vibrations of the vehicle body.

  The upper chamber R1, the lower chamber R2, and the pressure chamber C are filled with a liquid such as hydraulic oil. The lower chamber R2 is in sliding contact with the inner periphery of the cylinder 1 in the lower part of the cylinder 1 in the figure. A sliding partition wall F that partitions the gas chamber G is provided.

  The liquid filled in the upper chamber R1, the lower chamber R2, and the pressure chamber C, which are the working chambers, may be liquids such as water and an aqueous solution in addition to the working oil.

  The piston 2 is connected to one end of a piston rod 16 that is movably inserted into the cylinder 1, and the piston rod 16 projects outward from the upper end of the cylinder 1 in the figure. The piston rod 16 and the cylinder 1 are sealed with a seal member (not shown), and the cylinder 1 is in a liquid-tight state. Since the shock absorber D is set to a so-called single rod type, the volume of the piston rod 16 that enters and exits the cylinder 1 as the shock absorber D expands and contracts is the volume of the gas in the gas chamber G. The sliding partition F is expanded or contracted to compensate for the vertical movement in FIG. Thus, the shock absorber D is set to a single cylinder type, but instead of installing the sliding partition wall F and the gas chamber G, a reservoir is provided on the outer periphery or outside of the cylinder 1, and the piston rod 16 is provided by the reservoir. Volume compensation may be performed. In this case, the shock absorber D may be set to a double rod type instead of a single rod type.

  Further, in this embodiment, a damping valve V such as an orifice or a leaf valve is provided in the middle of the first passage 3, and the flow of liquid passing through the first passage 3 is caused by the damping valve V. Resistance can be given. Although not shown in detail, when two or more first passages 3 are provided in parallel, a part of the first passage 3 is set to be one-way from the upper chamber R1 to the lower chamber R2. The remaining passage may be set to one-way from the lower chamber R2 to the upper chamber R1, and a damping valve V having a configuration in which a known orifice and a leaf valve are arranged in parallel may be provided at the outlet of each passage. In addition to the configuration in which only the orifice, the leaf valve, or the orifice and the leaf valve are arranged in parallel, the damping valve V may adopt other configurations such as a configuration in which the choke and the leaf valve are arranged in parallel or a poppet valve. Naturally, it can be done.

  Subsequently, in this case, the second passage 4 opens from the side facing the upper chamber R1 as the other working chamber of the piston rod 16, and faces the lower chamber R2 as one working chamber and opens the pressure chamber C. The housing 15 to be formed communicates with the lower end in FIG. 1, and a pressure chamber C is provided in the middle thereof.

  In the case of this embodiment, the pressure chamber C is formed by a hollow portion 15a that is connected to the lower side of the piston 2 and that is provided in the housing 15 facing the lower chamber R2 that is one working chamber. A free piston 9 that slides in contact with the side wall and can move in the vertical direction in FIG. 1 divides the hollow portion 15a into a lower chamber 8 in FIG. 1 and an upper chamber 8 in FIG. . That is, the free piston 9 is slidably inserted into the pressure chamber C, and can be displaced in the vertical direction in FIG.

  The free piston 9 is connected to the other end of the spring element 10 whose one end is connected to the lower end of the hollow portion 15a forming the pressure chamber C, whereby the free piston 9 is positioned at a predetermined position in the pressure chamber C. At the same time, when the pressure chamber C is displaced from this position (hereinafter simply referred to as “neutral position”), an urging force proportional to the amount of displacement is applied from the spring element 10. The neutral position described above is a position where the free piston 9 is positioned by the spring element 10 with respect to the pressure chamber C, and does not necessarily have to be set at an intermediate point in the vertical direction of the hollow portion 15a.

  The pressure chamber C is vertically divided into a first chamber 7 and a second chamber 8 by a free piston 9, and the vibration direction that the shock absorber D expands and contracts and the movement direction of the free piston 9 are the same. If the entire shock absorber D vibrates in the vertical direction in FIG. 1 to avoid exciting the vertical vibration of the free piston 9 relative to the pressure chamber C, the moving direction of the free piston 9 Can be set in a direction perpendicular to the expansion / contraction direction of the shock absorber D, that is, in the left-right direction in FIG. 1, and the one chamber 7 and the other chamber 8 can be arranged in the lateral direction in FIG.

  Returning, the second flow path 4 communicates the one-side passage 5 that communicates the pressure chamber C with the lower chamber R2 as one working chamber, and the upper chamber R1 that serves as the other working chamber. The other side passage 6 is constituted.

  Specifically, the one-side passage 5 is provided in the housing 15, and communicates the lower chamber R2 and the one chamber 7, and a throttle 5a is provided in the middle thereof, and the flow of liquid passing therethrough Can be given resistance.

  Furthermore, the other side passage 6 communicates the upper chamber R1 which is the other side of the working chamber and the other chamber 8, opens from the side facing the upper chamber R1 of the piston rod 16 and passes through the piston 2 and the housing 15 to the other chamber. Leading to 8.

  As described above, the throttle 5a is provided in the one-side passage 5, and when the moving speed of the piston 2 with respect to the cylinder 1 becomes high during the expansion / contraction stroke of the shock absorber D, the difference between the upper chamber R1 and the lower chamber R2 is increased. The pressure also increases, and the resistance given to the flow of the passing liquid in the throttle 5a of the one-side passage 5 also becomes very large, so that the liquid that tries to move from the one chamber 7 to the lower chamber R2 or from the lower chamber R2 to the one chamber 7 The flow resistance is much larger than the flow resistance of the liquid in the first passage 3, and the liquid is difficult to travel between the upper chamber R1 and the lower chamber R2 via the pressure chamber C. Therefore, the damping force at that time is The resistance given to the liquid flow in the first passage 3 is substantially controlled.

  Therefore, when the moving speed of the piston 2 with respect to the cylinder 1 becomes high, the one-side port 11 that communicates the upper chamber R1 and the lower chamber R2 and the upper chamber R1 and the lower chamber R2 are communicated to reduce the damping force. The other side port 12, the one side relief valve 13 that opens and closes the one side port 11 using the pressure in the lower chamber R2 as a pilot pressure, and the other side relief valve that opens and closes the other side port 12 using the pressure in the upper chamber R1 as a pilot pressure. 14 is provided.

  Specifically, the one-side port 11 is branched from the other-side passage 6 in the second passage 4 and is communicated with the lower chamber R2 as one working chamber. A lower chamber R2 as a chamber communicates with an upper chamber R1 as the other working chamber, and a one-side relief valve 13 is provided in the middle. The one-side relief valve 13 includes a valve main body 13a, a spring 13b that urges the valve main body 13a in a direction to close the one-side port 11, and one upstream working chamber that faces the urging force of the spring 13b on the valve main body 13a. And a pilot passage 13c for applying the pressure of the lower chamber R2. This one-side relief valve 13 has a high piston speed when the shock absorber D contracts, and the difference between the pressure in the lower chamber R2 as one working chamber and the pressure in the upper chamber R1 as the other working chamber. When the valve opening pressure is reached, the valve main body 13a is moved in a direction to overcome the urging force of the spring 13b and push and contract the spring 13b to open the one side port 11, and the upper chamber R1 and the lower chamber R2 through the other side passage 6. Are communicated with each other to release the pressure in the lower chamber R2 to the upper chamber R1. On the contrary, when the shock absorber D extends, the one-side port 11 is kept closed. That is, the one-side relief valve 13 opens with the pressure in the lower chamber R2 as one working chamber as the pilot pressure.

  Similarly to the one-side port 11, the other-side port 12 is branched from the other-side passage 6 in the second passage 4 and communicated with the lower chamber R 2 as one working chamber. The lower chamber R2 as one working chamber communicates with the upper chamber R1 as the other working chamber, and the other side relief valve 14 is provided in the middle. The other-side relief valve 14 includes a valve body 14a, a spring 14b that urges the valve body 14a in the direction to close the other-side port 12, and the other working chamber upstream of the valve body 14a opposite to the urging force of the spring 14b. And a pilot passage 14c for applying the pressure of the upper chamber R1. The other-side relief valve 14 has a high piston speed when the shock absorber D extends, and the difference between the pressure in the upper chamber R1 as the other working chamber and the pressure in the lower chamber R2 as one working chamber. When a predetermined valve opening pressure is reached, the valve main body 14a is moved in a direction to overcome the urging force of the spring 14b and push and contract the spring 14b to open the other side port 12, and the lower chamber R2 and the upper chamber are connected via the other side passage 6. R1 is communicated to release the pressure in the upper chamber R1 to the lower chamber R2. On the contrary, when the shock absorber D contracts, the other side port 12 is kept closed. That is, the other-side relief valve 14 is opened using the pressure in the upper chamber R1 as the other working chamber as the pilot pressure.

  The valve opening pressures of the one-side relief valve 13 and the other-side relief valve 14 can be set separately and independently of each other without depending on the counterpart side.

  The one side port 11 and the other side port 12 communicate with the second passage 4, but may be provided separately from the second passage 4, and may be provided as a lower chamber as one working chamber of the cylinder 1. Since R2 and the upper chamber R1 as the other working chamber need only be able to communicate with each other, they may communicate with each other outside the cylinder 1, or may communicate with each other via the pressure chamber C. The location is not limited to that illustrated. However, as described above, there is an advantage that the structure of the shock absorber D can be simplified by making the second passage 4 and a part of the passage common, and the housing 15 faces one working chamber R2. In relation, when the upper chamber R1 and the lower chamber R2 are communicated with each other, the one side port 11 and the other side port 12 are branched from the other side passage 6 so as to be branched from the one side passage 5. The total length of the ports 11 and 12 can be shortened, and there is an advantage that each port 11 and 12 can be efficiently arranged in the shock absorber D.

  Further, the one-side relief valve 13 has a pressure on the upstream side of the one-side port 11 irrespective of the pressure on the downstream side of the one-side port 11 as viewed from the one-side relief valve 13 (in this case, the pressure in the upper chamber R1). In this case, it may be set to open the one-side port 11 when the pressure in the lower chamber R2 becomes equal to or higher than a predetermined pressure. Further, even when the other-side relief valve 14 is present, the one-side port 11 is viewed from the other-side relief valve 14. Regardless of the pressure on the downstream side of the other port 12 (in this case, the pressure in the lower chamber R2), the pressure on the upstream side of the other port 12 (in this case, the pressure in the upper chamber R1) becomes a predetermined pressure or higher. It may be set to open the other side port 12.

  Next, the operation of the shock absorber D will be described. First, the operation when the piston speed of the shock absorber D is low and the one side relief valve 13 and the other side relief valve 14 are not opened will be described. In this case, when the shock absorber D exhibits an expansion / contraction operation in which the piston 2 moves up and down in FIG. 1 with respect to the cylinder 1, one of the upper chamber R1 and the lower chamber R2 is compressed by the piston 2, and the upper chamber R1 and the lower chamber R2 are compressed. Since the pressure of the upper chamber R1 and the lower chamber R2 to be compressed is increased, the pressure of the upper chamber R1 and the lower chamber R2 of which the volume is expanded is decreased. A differential pressure is generated, and the liquid on the compression side of the upper chamber R1 and the lower chamber R2 moves to the enlargement side of the upper chamber R1 and the lower chamber R2 via the first passage 3 and the second passage 4. In the second passage 4, since the pressure chamber C provided in the middle is partitioned by the free piston 9, strictly speaking, the liquid in the upper chamber R1 (lower chamber R2) completely passes through the second flow path 4. However, although it does not move to the lower chamber R2 (upper chamber R1), when the free piston 9 is displaced in the pressure chamber C, it apparently passes from the upper chamber R1 to the lower chamber R2 via the second passage 4. Alternatively, the liquid moves from the lower chamber R2 to the upper chamber R1.

  Assuming that the one-side relief valve 13 and the other-side relief valve 14 do not open, the frequency of vibration input to the shock absorber D, that is, the frequency of vibration in the expansion / contraction direction of the shock absorber D is low. Even when the frequency is high, the operation when the piston speed in the expansion / contraction stroke of the shock absorber D is the same will be described. First, the operation of the shock absorber D during low-frequency input will be described. In this case, since the amplitude of vibration input to the shock absorber D is large, the upper chamber R1 and the lower chamber R2 move from the compression side to the expansion side. The flow rate of the cycle increases. The displacement by which the free piston 9 moves is substantially proportional to the flow rate. However, since the free piston 9 is biased by the spring element 10, the spring element received by the free piston 9 when the displacement of the free piston 9 increases. The energizing force from the pressure chamber 10 also increases, and the pressure on the side communicating with the enlarged side of the upper chamber R1 and the lower chamber R2 in the one chamber 7 and the other chamber 8 of the pressure chamber C is correspondingly reduced between the upper chamber R1 and the lower chamber R1. The pressure is lower than the pressure on the side communicating with the compression side of the chamber R2. That is, when the shock absorber D is extended, the pressure in the one chamber 7 is lower than the pressure in the other chamber 8, and conversely, when the shock absorber D is contracted, the pressure in the other chamber 8 is Lower than pressure. Therefore, regardless of whether the shock absorber D is extended or contracted, the differential pressure between the one chamber 7 and the lower chamber R2 is reduced, the flow rate passing through the throttle 5a is reduced, and the flow rate passing through the throttle 5a is reduced. The reduced amount increases the flow rate passing through the damping valve V of the first passage 3, and the damping force is kept large.

  On the contrary, at the time of high frequency input, since the input amplitude of vibration input to the shock absorber D is small, the flow rate of one cycle moving from the upper chamber R1 to the lower chamber R2 is small, and the displacement of the free piston 9 is also small. Then, the biasing force is also reduced from the spring element 10 received by the free piston 9. Accordingly, the pressure in the one chamber 7 of the pressure chamber and the pressure in the other chamber 8 are substantially equal, and the differential pressure between the one chamber 7 and the lower chamber R2 is maintained large, so that the flow rate passing through the throttle 5a is low. Accordingly, the flow rate passing through the damping valve V of the first passage 3 is reduced, and the damping force is also reduced accordingly.

  Thus, when the piston speed is low, the gain characteristic with respect to the frequency of the frequency transfer function of the differential pressure with respect to the flow rate is the characteristic as shown in FIG. Further, the damping force characteristic in the shock absorber D indicating the gain of the damping force with respect to the input of the vibration frequency generates a large damping force with respect to the vibration in the low frequency region, as shown by the solid line in FIG. The damping force can be reduced with respect to the vibration in the frequency range, and the change in the damping force of the shock absorber D can be made to depend on the input vibration frequency.

The frequency damping force characteristic of the shock absorber D is expressed by two bending point frequencies of Fa = K / {2 · π · A ² · (C1 + C2 + C3)} and Fb = K / {2 · π · A ² · (C2 + C3)}. In the region where F <Fa, the transfer gain is substantially C1, and in the region where Fa ≦ F ≦ Fb, the transmission gain gradually changes from C1 to C1 · (C2 + C3) / (C1 + C2 + C3). It is constant in the region> Fb. As is apparent from FIGS. 2 and 3, the shock absorber D generates a high damping force when the frequency of the input vibration is lower than the breakpoint frequency Fa, and the input vibration frequency becomes the breakpoint frequency Fb. It can be understood that when the frequency is higher, a low damping force is generated, and when the input vibration frequency is not less than the break frequency Fa and not more than the break frequency Fb, the damping force gradually decreases. In the case where the breakpoint frequency Fb value is set below the value of the unsprung resonance frequency of the vehicle among the plurality of breakpoint frequencies Fa and Fb, the shock absorber D receives vibration of the unsprung resonance frequency. Since a low damping force is always generated, the riding comfort in the vehicle is not impaired. In the region where the input vibration frequency exceeds the breakpoint frequency Fb, the phase lag of the damping coefficient ζ tends to disappear, and the generation of damping force follows the vibration input without delay. Will not be damaged.

  Further, the damping device D is configured so that the minimum bending point frequency Fa is set to be not less than the value of the sprung resonance frequency of the vehicle and not more than the value of the unsprung resonance frequency. 3 can reliably generate a high damping force, stabilize the vehicle posture, and prevent the passenger from feeling uneasy when turning the vehicle, as indicated by a broken line in FIG. Thus, in the frequency region lower than the corner frequency Fa, there is a tendency that the phase lag of the damping coefficient disappears, and the generation of the damping force follows the vibration input without delay. Never give.

  On the other hand, in a scene in which a sudden large-amplitude vibration that passes through the unevenness of the road surface while the vehicle is traveling is input to the shock absorber D, the piston 2 with respect to the cylinder 1 does not depend on the input vibration frequency. When the moving speed reaches the high speed region, the flow rate from the upper chamber R1 to the lower chamber R2 increases, and the resistance given to the liquid flow in the throttle 5a is higher than the resistance given to the liquid flow by the damping valve V of the first passage 3. The liquid becomes very large, and the liquid tries to move from the upper chamber R1 to the lower chamber R2 only through the first passage 3. However, in the case of the shock absorber D of the present embodiment, when the piston speed is high and moves downward in FIG. 1 to exhibit a contraction operation, the high pressure in the lower chamber R2 acts on the one-side relief valve 13. Then, the one-side relief valve 13 opens and the upper chamber R1 and the lower chamber R2 communicate with each other through the one-side port 11. Further, when the piston speed is high and moves upward in FIG. 1 to exhibit an extension operation, the high pressure in the upper chamber R1 acts on the other side relief valve 14, and the other side relief valve 14 opens. The upper chamber R1 and the lower chamber R2 communicate with each other through the other side port 12.

  Accordingly, when the shock absorber D exhibits an expansion / contraction operation at a high speed, the liquid flows from the upper chamber R1 to the lower chamber R2 via the one side port 11 or the other side port 12 as well as the first passage 3 or The lower chamber R2 moves from the lower chamber R1 to the upper chamber R1, so that the damping force generated by the shock absorber D is reduced and does not increase to the value set in the specification of the damping valve V of the first passage 3.

  As described above, in the shock absorber D of the present embodiment, even in a scene where the piston speed is high such that the vehicle passes through the unevenness of the road surface while traveling, the broken line in FIGS. As shown by the solid lines in FIG. 4 and FIG. 5, the gradient of the damping force with respect to the piston speed with respect to the frequency damping force characteristic and the speed damping force characteristic of the conventional shock absorber shown in FIG. The damping force can be reliably reduced, so that the damping force stays high like the conventional shock absorber, and the effect of insulating the transmission of vibration from the axle to the vehicle body disappears. Can be eliminated, and the ride comfort in the vehicle can be improved.

  Further, when the shock absorber D is contracted, only the one-side relief valve 13 is opened, and when the shock absorber D is extended, only the other-side relief valve 14 is opened, so that the speed damping force characteristic when the shock absorber D is contracted. Can be adjusted by setting the one-side relief valve 13 and the one-side port 11, and the speed damping force characteristic when the shock absorber D is extended can be adjusted by setting the other-side relief valve 14 and the other-side port 12. That is, the speed damping force characteristics at the time of contraction and expansion of the shock absorber D can be set independently, and the degree of tuning freedom is greatly improved.

  That is, as shown in FIG. 5, the position of the contraction side folding point a of the shock absorber D on the contraction side, the inclination after the folding point a, and the speed damping force characteristic on the expansion side of the shock absorber D The position of the break point b on the extension side and the inclination after the break point b can be set independently. The position of the break point a is determined by the valve opening pressure of the one-side relief valve 13 and the inclination after the break point a. Is the opening pressure of the other side relief valve 14 at the position of the break point b, and the inclination after the break point b is due to the opening area of the other side port 12 and the passage resistance. Each can be freely set according to the intention of the designer.

  As described above, since the gradient of the speed damping force characteristic in the contraction stroke of the shock absorber D can be reduced, the effect of reducing the impact shock when the wheel rides on the road surface protrusion is increased, and the gradient of the speed damping force characteristic in the extension stroke is increased. Since it can be reduced, it is possible to mitigate the impact generated when the submerged vehicle body is turned back, and the speed damping force characteristics can be freely set on both sides of the expansion and contraction. The impact shock can be reduced while firmly supporting the vehicle body when turning, and the vehicle can be provided with a supple but firm suspension.

  The velocity damping force characteristics of the damping valve V shown in FIG. 5 are those when the damping valve V has a configuration in which an orifice and a leaf valve are arranged in parallel. As shown in FIG. 5, the damping force characteristic when the piston speed is in the extremely low speed range with the vibration input in the low frequency range is established by the liquid preferentially passing through the orifice in the damping valve V in the first passage 3. The inflection point appears in the damping force characteristic in the middle of the low speed region of the piston speed because the leaf valve is opened and the characteristic of the leaf valve becomes dominant.

  In addition, when the piston speed is in the extremely low speed range and the low speed range with vibration input in the high frequency range, as shown in FIG. 3, a relatively large damping force is applied to the low frequency, and to the high frequency. A relatively low damping force can be exhibited, and a damping force having an appropriate magnitude can be generated according to the frequency. 3 is set to a value greater than the value of the sprung resonance frequency of the vehicle and less than the value of the unsprung resonance frequency of the vehicle. By setting the point frequency Fb to be equal to or lower than the unsprung resonance frequency of the vehicle, the shock absorber D can generate a high damping force with respect to the vibration input of the sprung resonance frequency and stabilize the posture of the vehicle. Therefore, when the vehicle turns, it is possible to prevent the passenger from feeling uneasy, and when a vibration with an unsprung resonance frequency is input, a low damping force is always generated. This makes it possible to improve the riding comfort of the vehicle.

  Although it is conceivable to reduce the damping force when the piston speed becomes high by reducing the resistance at the damping valve V in the first passage 3, this is a case where the piston speed is low. The damping force generated with respect to the vibration in the low frequency range is also reduced, causing a deficiency in the damping force and causing the passenger to feel uneasy when turning the vehicle. However, in the shock absorber D of the present embodiment, Since the damping force when the piston speed is high can be reduced without reducing the resistance in the damping valve V of the first passage 3, such a problem does not occur.

  Further, as illustrated and described in FIG. 1, the one-side port 11 and the other-side port 12 are not connected via the pressure chamber C which is a mechanism for raising and lowering the damping force according to the vibration frequency of the shock absorber D. When the configuration in which the lower chamber R2 as the working chamber is communicated with the upper chamber R1 as the other working chamber, the operation of the one side relief valve 13 and the other side relief valve 14 is the same as that of the one chamber 7 in the pressure chamber C. Since the pressure in the other chamber 8 is less likely to be affected, when the piston speed is operated at a low speed or less, the damping device D can generate the desired frequency damping force characteristic as shown in FIG.

  Further, the housing 15 faces the lower chamber R2 as one working chamber, and the one side port 11 and the other side port 12 are branched from the other side passage 6, so that the housing 15 other than the housing 15 forming the pressure chamber C is provided. The one-side port 11 and the other-side port 12 can be formed, so that the structure of the housing 15 is not complicated and lengthened, and the one-side port 11 and the other-side port 12 are excessively installed in the shock absorber D. Therefore, it is possible to prevent unnecessary increase in the size of the shock absorber D.

  In the present embodiment, in order to explain the operation of the one-side relief valve 13 and the other-side relief valve 14, for the sake of convenience, the piston speed is divided into low speed and high speed sections. The boundary speed is a speed at which the one-side relief valve 13 and the other-side relief valve 14 are opened, and the low-speed and high-speed boundary speeds may not be the same on the expansion side and the contraction side.

  In the above-described shock absorber D, the pressure chamber is formed in the cylinder, but it can also be provided outside the cylinder.

  Although the shock absorber D has been conceptually described above, the structure of the shock absorber D1 in a specific example will be shown and described below.

  As shown in FIG. 6, the specific shock absorber D1 basically includes a cylinder 20, an upper chamber R1 and a lower chamber that are slidably inserted into the cylinder 20 and are two working chambers. A piston 21 as a partition member that is partitioned into R2, a piston rod 22 that is movably inserted into the cylinder 20 and connected to the piston 21 at one end, and is formed in the piston 21 and communicates with the upper chamber R1 and the lower chamber R2. One side attenuation passage 21a and the other side attenuation passage 21b as the first passage, one side passage 24 and the other side passage 25 as the second passage communicating the upper chamber R1 and the lower chamber R2, and as a damping valve The leaf valves V1 and V2, the housing 23 fixed to one end of the piston rod 22 to form the pressure chamber C1, and the pressure chamber C1 are slidably inserted into the housing 23. The chamber is divided into a first chamber 26 communicated with the lower chamber R2 as one working chamber via the side passage 24 and a second chamber 27 communicated with the upper chamber R1 as the other working chamber via the other passage 25. A free piston 28, a pair of coil springs 29 and 30 that are housed in the one chamber 26 and the other chamber 27 and elastically support the free piston 28 from both sides, and one that communicates the upper chamber R1 and the lower chamber R2. The side port 31, the other side port 32 that similarly communicates the upper chamber R1 and the lower chamber R2, and the one side relief valve 33 that opens and closes the one side port 31 using the pressure in the lower chamber R2 as one working chamber as a pilot pressure. And the other-side relief valve 34 that opens and closes the other-side port 32 using the pressure of the upper chamber R1 as the other working chamber as a pilot pressure. Although not shown in the drawing, similarly to the shock absorber D shown in FIG. 1, a sliding partition is provided below the cylinder 20 and a gas chamber is provided.

  Hereinafter, each part will be described in detail. First, the piston rod 22 has a small-diameter portion 22a formed on the lower end side in FIG. 6, and a screw portion 22b formed on the distal end side of the small-diameter portion 22a.

  The piston rod 22 is formed with the other side passage 25 that opens from the side facing the upper chamber R1 as the other working chamber of the piston rod 22 and passes through the tip of the small diameter portion 22a. In the figure, a valve that serves as a resistor is not provided in the middle of the other side passage 25, but a valve such as a throttle may be provided.

  The piston 21 is formed in an annular shape, and a small diameter portion 22a of the piston rod 22 is inserted on the inner peripheral side thereof. Specifically, the piston 21 includes a disk portion 21c having a one-side attenuation passage 21a and a second-side attenuation passage 21b as a first passage communicating the upper chamber R1 and the lower chamber R2, and a housing 23 from the outer periphery of the disk portion 21c. A cylindrical skirt 21d that rises toward the side and faces the inner surface of the cylinder is provided. Further, the upper end in FIG. 6 of the one-side damping passage 21a is opened and closed by a leaf valve V1 as a damping valve, and the lower end in FIG. 6 of the other other-side damping passage 21b is also laminated on the lower surface in FIG. It is opened and closed by a leaf valve V2 as a damping valve.

  The leaf valve V1 has an annular shape, and a small diameter portion 22a of the piston rod 22 is inserted on the inner peripheral side, and the annular valve stopper 35 for restricting the amount of deflection of the leaf valve V1 is shown in FIG. It is laminated on the middle upper surface. Similarly, the leaf valve V2 has an annular shape, and a small-diameter portion 22a of the piston rod 22 is inserted on the inner peripheral side, and is laminated on the lower surface of the disk portion 21c of the piston 21 in FIG.

  The leaf valve V1 is bent by the pressure difference between the lower chamber R2 and the upper chamber R1 when the shock absorber D1 contracts, opens the one-side damping passage 21a, and moves from the lower chamber R2 to the upper chamber R1. In addition to providing resistance to the flow, the one-side damping passage 21a is closed when the shock absorber D1 is extended, and functions as a one-side damping valve. In contrast to the leaf valve V1, the other leaf valve V2 opens the other-side damping passage 21b when the shock absorber D1 extends, and closes the other-side damping passage 21b when contracting, and serves as the other-side damping valve. Function. That is, the leaf valve V1 is a damping valve that generates a compression side damping force when the shock absorber D is contracted, and the other leaf valve V2 is a damping valve that generates an expansion side damping force when the shock absorber D is extended. . Even when the one-side attenuation passage 21a and the other-side attenuation passage 21b are closed by the leaf valves V1, V2, the upper chamber R1 and the lower chamber R2 are communicated with each other by a known orifice (not shown). The orifice is formed, for example, by providing a notch on the outer periphery of the leaf valves V1, V2, or by providing a recess in the valve seat on which the leaf valves V1, V2 are seated.

  The screw portion 22b of the piston rod 22 has a spacer 36, the other side relief valve 34, a valve disc 37 having one side port 31 and the other side port 32, and one side relief valve 33 from below the leaf valve V2. The notched spacer 38 and the partition wall cylinder 39 are stacked and assembled, and the housing 23 forming the pressure chamber C1 is screwed. The housing 23 allows the above-described piston 21, leaf valves V1, V2, valve stopper 35, The spacer 36, the other side relief valve 34, the valve disk 37, the one side relief valve 33, the notched spacer 38 and the partition cylinder 39 are fixed to the piston rod 22. Thus, the housing 23 not only forms the pressure chamber C1 inside, but also plays a role of fixing the piston 21 and the valve disc 37 having the one side port 31 and the other side port 32 to the piston rod 22. .

  The valve disk 37 is annular, and has an annular window 31a formed at the housing side end which is the lower end in FIG. 6, an annular window 32a formed at the piston side end which is the upper end in FIG. An inclined passage 31b that opens from the outer peripheral side of the annular window 32a at the end and communicates with the annular window 31a, and an inclined passage 32b that opens from the outer peripheral side of the annular window 31a at the housing side and communicates with the annular window 32a. The annular window 31a and the inclined passage 31b constitute one side port 31, and the annular window 32a and the inclined passage 32b constitute the other side port 32. Since the valve disc 37 is disposed in the lower chamber R2 as one working chamber, the one-side port 31 and the other-side port 32 communicate with the lower chamber R2, and a relief passage 41 and a second passage which will be described later. Of these, the other passage 25 communicates with the upper chamber R1 as the other working chamber.

  And the other side relief valve 34 which consists of an annular plate is laminated | stacked on the piston side end which is the upper end in FIG. 6 of the valve disc 37, This other side relief valve 34 opens and closes the annular window 32a. Specifically, the other-side relief valve 34 is fixed to the small-diameter portion 22a of the piston rod 22 by screwing the housing 23 to the piston rod 22, and the outer peripheral side is a free end. The other-side relief valve 34 serves as the other working chamber via the other-side port 32, a relief passage 41, which will be described later, and the other-side passage 25, with the area facing the annular window 32 a on the side surface of the valve disk as the pressure receiving area. The pressure of the upper chamber R1 is received, and the pressure of the lower chamber R2 as one working chamber is received on the side opposite to the valve disc, and the piston speed when the shock absorber D1 extends becomes high, and the upper chamber R1 Exceeds the pressure in the lower chamber R2, and when these differential pressures reach a predetermined valve opening pressure, the second port 32 is opened. That is, the other-side relief valve 34 opens using the pressure in the upper chamber R1 as the other working chamber as the pilot pressure.

  For setting the valve opening pressure of the other side relief valve 34, for example, a difference is provided in the axial direction height in FIG. 6 between the outer peripheral side and the inner peripheral side of the annular window 32a of the valve disk 37, and the other side relief valve is preset. When the initial deflection is given to 34, the initial deflection amount can be adjusted, and the other side relief valve 34 is composed of a plurality of annular plates, and the inner diameter is larger than the inner diameter of the annular plate. In the case of adopting a configuration in which a ring having a smaller diameter than the outer diameter is interposed between the annular plates and applying an initial deflection to the annular plate laminated on the side opposite to the valve disc from the ring, the initial deflection amount should be adjusted. Can also be performed. Note that the number of annular plates in the other-side relief valve 34 can be appropriately changed according to a desired speed damping force characteristic.

  The one side relief valve 33 which consists of an annular plate is laminated | stacked on the housing side end which is the lower end in FIG. 6 of the valve disc 37, and this one side relief valve 33 opens and closes the annular window 31a. Specifically, the one-side relief valve 33 is fixed to the small-diameter portion 22a of the piston rod 22 by screwing the housing 23 to the piston rod 22 in the same manner as the other-side relief valve 34, The outer peripheral side is a free end, and the pressure of the lower chamber R2 as one working chamber is received through the one side port 31 with the area facing the annular window 31a of the side surface of the valve disk as the pressure receiving area, Thus, the pressure of the upper chamber R1 as the other working chamber is received, the piston speed when the shock absorber D1 contracts becomes high, the lower chamber R2 exceeds the pressure of the upper chamber R1, and the differential pressure between them is a predetermined opening. When the valve pressure is reached, it bends and opens the one-side port 31. That is, the one-side relief valve 33 opens using the pressure in the lower chamber R2 as one working chamber as a pilot pressure. About the setting of the valve opening pressure of the one side relief valve 33, it can set by the method similar to the other side relief valve 34 mentioned above. Similarly to the other-side relief valve 34, the number of annular plates in the one-side relief valve 33 can be appropriately changed according to the desired speed damping force characteristic.

  Even if the one-side relief valve 33 and the other-side relief valve 34 are stacked on the valve disc 37, the inclined passages 31b and 32b open from the outer periphery of the annular windows 32a and 31a, respectively. The entrance of the other side port 32 is not blocked, and similarly, the other side relief valve 34 does not close the entrance of the one side port 31.

  When the one-side relief valve 33 and the other-side relief valve 34 are stacked on both ends of the valve disc 37, the one-side relief valve 33 does not block the inlet of the other-side port 32, and the other-side relief valve 34 Since it is sufficient that the entrance of the one side port 31 is not blocked, it is not necessary to provide the annular windows 31a and 32a. Furthermore, as shown in FIG. 7, the one side port 31 and the other side port 31 are not provided. When a so-called petal-type valve seat 37a that surrounds the outlet end of 32 is provided independently, the one-side port 31 and the other-side port 32 along the axial direction of the valve disc 37 are not provided without the inclined passages as described above. May be provided on the same circumference, and when the diameters of the annular groove 31a and the annular groove 32a are made different as shown in FIG. The passages 31c and 32c along the axial direction of the disk 37 are respectively connected to the annular grooves 31a and 32a, and the other side relief valve 34 for opening and closing the large-diameter annular groove 32a is disposed on the inner peripheral side from the other side port 32. The other side relief valve 34 may be provided with through holes 51 and 54 penetrating therethrough so that the one side port 31 is not blocked. The other side relief valve 34 in FIG. 8 is configured by laminating a plurality of annular plates 50. In this case, as shown in FIG. 9, the same circle of the annular plate 50 farthest from the valve disk 37 is used. If a plurality of through holes 51 are provided on the circumference, and the other annular plate 52 is provided with a through hole 54 on an arc facing the through hole 51, the lap area of these through holes 51 and 54 is reduced. Even if the annular plates 50 and 52 are not positioned in the circumferential direction, an unnecessary throttle valve is not formed at the inlet of the one-side port 31, and the assembling property is improved. When the other side port 32 is arranged on the inner peripheral side from the one side port 31, a through hole may be provided in the one side relief valve 33. In the valve disc 37 shown in FIGS. 7 and 8, the one-side port 31 and the other-side port 32 are opened in a direction along the axial direction of the valve disc 37, so that the valve disc has a structure requiring an inclined passage. Compared to the above, machining is easier, machining costs are reduced, and machining time is shortened.

  By the way, in the case of the present embodiment, the inner diameter of the skirt 21d in the piston 21 is larger than the outer diameter of the annular other-side relief valve 34 that directly faces the piston 21, and the valve disk 37 is placed inward of the skirt 21d. A part of can be put in. By doing so, the distance from the housing 23 to the piston 21 can be shortened while ensuring the sliding length that is the axial length of the piston 21 with respect to the cylinder 20, so that the stroke length of the shock absorber D1 can be reduced. It is easy to secure, and backlash with respect to the cylinder 20 of the piston 21 as a partition member is suppressed, so that sliding resistance can be reduced and a smooth stroke can be realized.

  The notched spacer 38 is stacked immediately below the one-side relief valve 33 in FIG. 6, and has a cylindrical shape with a top, and is provided with a hole 38 a through which the small diameter portion 22 a of the piston rod 22 is inserted. A plurality of notches 38b are provided at the lower end of the cylindrical portion. When the notched spacer 38 is fixed to the small diameter portion 22a of the piston rod 22, the inside of the notched spacer 38 branches off from the other side passage 25 provided in the piston rod 22 and opens to the side of the small diameter portion 22a. Facing the through hole 40, the inside of the notched spacer 38 communicates with the upper chamber R <b> 1 as the other working chamber via the other side passage 25.

  The partition wall tube 39 is a bottomed tube shape, and a hole 39a through which the small diameter portion 22a of the piston rod 22 is inserted is provided at the bottom, and the tube portion has a diameter that can cover the notched spacer 38. Is set. When the partition cylinder 39 is fixed to the small diameter portion 22 a of the piston rod 22, the cylinder portion is the outer periphery of the valve disc 37 with the one-side relief valve 33 and the notched spacer 38 sandwiched between the valve disc 37. And a gap is defined from the lower chamber R2 as one working chamber in cooperation with the valve disk 37. This gap communicates with the upper chamber R1 as the other working chamber via the notch 38b of the notched spacer 38, the through hole 40 and the other side passage 25, and the one side port 33 and the other side port formed in the valve disk 37. 34, a relief passage 41 is formed. That is, the partition cylinder 39 forms a relief passage 41 defined from the lower chamber R2 as one working chamber. Since the notch 38b to be provided in the notched spacer 38 is for connecting the relief passage 41 to the second passage, in addition to the notch formed from the lower end of the tubular portion, for example, the tubular portion In this case, the relief passage 41 can be partitioned and the opening and closing of the one-side port 31 in the one-side relief valve 33 accommodated in the partition tube 39 is also possible. Any shape that does not interfere with the piston 21 and that does not interfere with the piston 21 may be used, and is not limited to the shape illustrated and described above. The partition cylinder 39 may be integrated with the valve disk 37 or may be integrated with the housing 23. In this case, the partition cylinder 39 is provided on the outer periphery of the valve disk 37, or the housing 23 It is only necessary to provide the partition tube 39 in the nut portion 42 or the housing tube 44, and it is not necessary to directly fix to the small diameter portion 22a of the piston rod 22, and it is not necessary to prepare the partition tube as a separate part. There is no need to worry that a gap is generated between the valve disk 37 or the housing 23 and the liquid escapes from the gap.

  When a gap that cannot be overlooked is generated between the partition cylinder 39 and the valve disk 37, a seal member such as an O-ring, a square ring, or an annular packing may be interposed.

  Next, the housing 23 will be described. The housing 23 includes a nut portion 42 with a flange 43 that is screwed into the screw portion 22 b of the piston rod 22, and a bottomed cylindrical storage tube 44 that is suspended from the outer periphery of the nut portion 42. The upper end opening in FIG. 6 of the cylinder 44 is crimped toward the outer periphery of the flange 43 and attached to the outer periphery of the flange 43, and the housing cylinder 44 and the nut portion 42 are integrated. A pressure chamber C1 is defined in the lower chamber R2. In addition, when integrating the nut part 42 and the accommodation cylinder 44, it is also possible to employ | adopt other methods, such as welding other than the said caulking process.

  A free piston 28 is slidably inserted into the pressure chamber C1 formed as described above, and the pressure chamber C1 is connected to the other chamber 27 on the upper side and the one chamber 26 on the lower side in FIG. It is partitioned.

  Further, as described above, the nut portion 42 includes the flange 43 on the side, and a screw portion 42a is formed on the inner periphery thereof. By screwing the screw portion 42a to the screw portion 22b of the piston rod 22, The housing 23 can be fixed to the small diameter portion 22 a of the piston rod 22. Therefore, if the cross-sectional shape of the outer periphery of the housing cylinder 44 is a shape other than a perfect circle, for example, a shape with a part cut away or a hexagonal shape, the operation of screwing the housing 23 onto the tip of the piston rod 22 is performed. It becomes easy.

  The housing cylinder 44 has a bottomed cylindrical shape, and a lower inner periphery in FIG. 6 of the cylinder portion 44a is formed to have a small diameter, and a stepped portion 44b is formed therein, and the bottom portion 44c has a one-side passage. A fixed orifice 45 constituting a part of 24 is provided.

  The free piston 28 inserted into the pressure chamber C <b> 1 formed by the nut portion 42 and the housing cylinder 44 is formed in a bottomed tubular shape, and is slidably in contact with the sliding cylinder 28 a that is in sliding contact with the housing cylinder 44. A bottom 28b that closes one end of the contact tube 28a, a convex portion 28c that is provided at the lower end in FIG. 6 of the bottom 28b and protrudes toward the bottom 44c of the housing tube 44, and an annular groove formed on the outer periphery of the slide contact tube 28a 28d, a hole 28e for communicating the annular groove 28d with the one chamber 26, and an annular friction member receiving groove 28f formed on the outer periphery of the sliding contact tube 28a on the end side which is the upper side in FIG. 6 from the annular groove 28d. Are inserted into the pressure chamber C1 with the cylinder portion 28a being in sliding contact with the inner periphery of the housing cylinder 44 with the inner side facing the nut portion 42, and the pressure chamber C1 is connected to the one chamber 26 and the other chamber 27. It is divided into.

  Also, in order to apply an urging force to the free piston 28 in proportion to the amount of displacement of the free piston 28 with respect to the housing 23, the flange 43 of the nut portion 42 and the free piston 28 are provided in the other chamber 27. Coil springs 30 and 29 as spring elements, respectively, between the inside of the bottom portion 28b of the inner cylinder 44 and between the bottom portion 44c of the housing cylinder 44 and the outside of the bottom portion 28b of the free piston 28. The free piston 28 is sandwiched from above and below by the spring elements of the coil springs 29 and 30 and is elastically supported after being positioned at a predetermined neutral position in the pressure chamber C1.

  As the spring element, it is sufficient that the free piston 28 can be elastically supported, and other elements than the coil springs 29 and 30 may be employed. For example, the free piston 28 may be elastically supported using an elastic body such as a disc spring. It may be. When a single spring element whose one end is connected to the free piston 28 is used, the other end may be fixed to the nut portion 42 or the housing cylinder 44.

  The lower end of the coil spring 30 in the drawing is fitted to the innermost periphery of the deepest portion of the cylindrical portion 28 a of the free piston 28 and is positioned in the radial direction. By being inserted, it is centered to prevent positional displacement with respect to the free piston 28, thereby making it possible to stably apply an urging force to the free piston 28.

  In addition, the inner periphery of the cylindrical portion 28a of the free piston 28 is expanded in diameter compared to the deepest portion thereof, so that when the coil spring 30 is compressed and the winding diameter is expanded, the wire material of the coil spring 30 is the cylindrical portion. It is also possible to prevent the occurrence of contamination by preventing rubbing on the inner periphery of 28a.

  Further, as described above, the convex portion 28c has a function of centering the coil spring 29, and its height (vertical length in FIG. 6) is set to a height that can sufficiently prevent the coil spring 29 from climbing up. Has been.

  Subsequently, in the case of this embodiment, the above-described free piston 28 includes the hole 28e that passes through the thickness of the free piston 28 and communicates the annular groove 28d with the one chamber 26, as described above.

  Further, two variable orifices 46 communicating with the lower chamber R2 and the inside of the storage cylinder 44 are provided in the cylinder portion 44a of the storage cylinder 44, and the free piston 28 is elastically supported by the coil springs 29 and 30 in the variable orifice 46. When supported and in the neutral position, the one chamber 26 and the lower chamber R2 are always communicated with the annular groove 28d, and the free piston 28 is displaced to the stroke end. That is, the lower end of the nut portion 42 in FIG. Or if it displaces until it contacts the step part 44b of the accommodation cylinder 44, it will overlap with the outer periphery of the cylinder part 28a of the free piston 28 completely, and will be obstruct | occluded. That is, the one-side passage 24 includes an annular groove 28d, a variable orifice 46, a hole 28e, and a fixed orifice 45. Two variable orifices 46 are provided, but the number thereof is arbitrary, and the number of fixed orifices 45 is also the same.

  That is, in the case of this specific shock absorber D1, when the displacement amount from the neutral position of the free piston 28 becomes a predetermined displacement amount, the cylindrical portion 28a is in a state where all the openings of the variable orifice 46 face the annular groove 28d. Then, the flow area of the variable orifice 46 begins to decrease gradually, and the flow resistance in the one-side passage 24 gradually increases. Therefore, the predetermined displacement amount can be arbitrarily set by setting the vertical width of the annular groove 28d in FIG. 6 and the opening position of the variable orifice 46 on the inner peripheral side of the housing cylinder 44. In this embodiment, the flow area of the variable orifice 46 gradually decreases as the amount of displacement of the free piston 28 increases, and when the free piston 28 reaches the stroke end, the variable orifice 46 is completely cylindrical. The flow passage resistance in the one-side passage 24 is maximized, and the one chamber 26 is communicated with the lower chamber R2 only by the fixed orifice 45.

  Further, a friction member 48 having elasticity is mounted in the friction member housing groove 28 f of the free piston 28 of the present embodiment, and this friction member 48 slides on the inner periphery of the cylinder portion 44 a of the housing cylinder 44. In contact therewith, the displacement of the free piston 28 relative to the housing cylinder 44 is suppressed. Specifically, when the amplitude of the shock absorber D1 is large, that is, when the displacement of the free piston 28 is in a low frequency range, the friction member 48 suppresses the displacement of the free piston 28 relative to the housing 23, and the amplitude of the shock absorber D1. When the vibration is small, that is, when the displacement of the free piston 28 is small, the friction member 48 is elastically deformed and the frictional force becomes slight, so that the displacement of the free piston 28 relative to the housing 23 is not suppressed. ing. Although the friction member 48 is mounted on the free piston 28 side, an annular friction member storage groove may be provided in the storage cylinder 44, and the friction member may be mounted thereon.

  Although the shock absorber D1 is configured as described above, when the piston speed is in the extremely low speed region and the low speed region, as in the shock absorber D, the frequency of vibration input to the shock absorber D1 is low. Exhibits a large damping force, and conversely, when the frequency of vibration input to the shock absorber D1 is high, a small damping force is exhibited, and the riding comfort in the vehicle can be improved.

  Even in the shock absorber D1, like the shock absorber D, when the telescopic operation is performed at a high speed, the one-side relief valve 33 or the other-side relief valve 34 opens, so that the liquid is first From the upper chamber R1 to the lower chamber R2 or from the lower chamber R2 to the upper chamber R1 through the one side port 31 or the other side port 32 as well as the one side attenuation passage 21a and the other side attenuation passage 21b as passages. The damping force generated by the shock absorber D is reduced, and the value does not increase to the value set by the specifications of the leaf valves V1 and V2.

  Accordingly, even in the shock absorber D1 of the present embodiment, the piston speed functions in the same manner as the shock absorber D described above in a scene where the piston speed is high such that the vehicle passes through the road surface unevenness while traveling. Since the damping force can be reduced by reducing the gradient of the damping force against the vehicle, the damping force stays high like conventional shock absorbers, and the transmission of vibration from the axle to the vehicle body is insulated. The problem that the effect disappears can be solved, and the riding comfort in the vehicle can be improved.

  Further, when the shock absorber D1 contracts, only the one-side relief valve 33 opens, and when the shock absorber D1 extends, only the other-side relief valve 34 opens, so that the speed damping force characteristic when the shock absorber D1 contracts. Can be adjusted by setting the one-side relief valve 33 and the one-side port 31, and the speed damping force characteristic when the shock absorber D <b> 1 is extended can be adjusted by setting the other-side relief valve 34 and the other-side port 32. That is, the speed damping force characteristics of the shock absorber D1 during contraction and expansion can be set independently, and the degree of tuning freedom is greatly improved.

  Therefore, similarly to the shock absorber D, even with this shock absorber D1, it is possible to reduce impact shock while firmly supporting the vehicle body when turning, and to provide a supple but firm suspension to the vehicle. Can do.

  Further, the one-side port 31 and the other-side port 32 adopt a configuration in which the lower chamber R2 as one working chamber communicates with the upper chamber R1 as the other working chamber without passing through the pressure chamber C1. Since the operations of the relief valve 33 and the other-side relief valve 34 are less likely to affect the pressure in the one chamber 26 and the other chamber 27 in the pressure chamber C1, when the piston speed operates at a low speed or less, the shock absorber D1 is aimed as intended. It is possible to generate a frequency damping force characteristic.

  The housing 23 faces the lower chamber R2 as one working chamber, and the one side port 31 and the other side port 32 are branched from the other side passage 25, so that one side other than the housing 23 forming the pressure chamber C1 is provided. The port 31 and the other side port 32 can be formed, and the structure of the housing 23 is not complicated or lengthened. Excessive cost is required when installing the one side port 31 and the other side port 32 in the shock absorber D1. An increase in the size of the shock absorber D1 can be prevented, and an increase in the size of the shock absorber D1 can be prevented.

  In this case, since one side relief valve 33 and the other side relief valve 34 are stacked on one valve disk 37, one valve disk 37 is used for the two relief valves 33 and 34. As a result, the number of parts can be reduced and unnecessary weight increase of the shock absorber D1 can be avoided, and the entire length of the shock absorber D1 is not unnecessarily lengthened even when assembled to the piston rod 22. It becomes.

  Further, in the case of this embodiment, by fixing the housing 23 to the piston rod 22, the piston 21 as a partition member, leaf valves V1 and V2 as damping valves, one side relief valve 33, the other side relief valve 34, Since all of the housing 23 that forms the valve disk 37 and the pressure chamber C1 and accommodates the free piston 28 is fixed to the piston rod 22, the assembly of the shock absorber D1 is facilitated, and the processing cost is reduced.

  Further, in the shock absorber D1 of this embodiment, the free piston 28 is provided with a friction member 48 having elasticity, and the friction member 48 is a housing of the free piston 28 for vibration in a low frequency range. Therefore, the displacement of the free piston 28 relative to the housing 23 can be prevented from being suppressed with respect to vibration in a high frequency range. For this reason, the free piston 28 operates more than necessary with respect to vibrations in the low frequency range, resulting in a frequency damping characteristic in which the damping force decreases even with respect to vibrations in the low frequency range as shown by the broken line in FIG. As shown by the solid line in the figure, the desired frequency damping force characteristics can be obtained, so low damping force is ensured in scenes where the input vibration frequency is high, such as when the vehicle is traveling on uneven road surfaces. And a high damping force can be obtained in a scene where the input vibration frequency is low, such as when the vehicle is turning.

  As described above, when the friction member 48 is formed of a member suitable for sealing, such as an O-ring or a square ring, the one chamber 26 is connected to the one chamber 26 via a sliding gap between the free piston 28 and the housing cylinder 44. The alternating current of the liquid in the other chamber 27 can be prevented, and the drop of the damping force during the low frequency vibration can be more reliably prevented.

  Next, a shock absorber D2 as a modification of the specific shock absorber D1 described above will be described. In the shock absorber D2 in this modification, as shown in FIG. 11, a configuration of the partition cylinder 60 that defines the relief passage 61, and a configuration in which the relief passage 61 is connected to the second passage through the pressure chamber C1. Is different from the above-described shock absorber D1.

  In addition, since description overlaps, below, the buffer device D2 demonstrates in detail about a different part from the buffer device D1, and suppose that detailed description is abbreviate | omitted about the same part as the buffer device D1.

  First, the partition cylinder 60 has a structure in which the shock absorber D1 is fixed to the small diameter portion 22a of the piston rod 22. However, in the shock absorber D2, the outer periphery of the valve disk 37 and the housing 23 are arranged. A structure that fits to the outer periphery is adopted.

  Specifically, the partition wall cylinder 60 has a fitting portion 60a fitted to the outer periphery of the nut portion 42 of the housing 23 and an inner diameter larger than the fitting portion 60a, and the upper end in FIG. And a cylindrical portion 60b.

  The nut portion 42 of the housing 23 is thicker than the shock absorber D1 described above, and the outer periphery of the upper end in FIG. 11 is set to a small diameter to provide a small diameter portion 42b. The small diameter portion 42b The fitting portion 60a of the partition wall cylinder 60 is fitted to the fitting. A seal ring 62 is interposed between the fitting portion 60a and the small diameter portion 42b, and the space between the partition wall cylinder 60 and the housing 23 is sealed.

  Furthermore, in this embodiment, a disc-like plate 63 is laminated on the upper end of the nut portion 42 of the housing 23 in FIG. 11, and this plate 63 abuts on the upper end of the fitting portion 60 a of the partition wall cylinder 60. Thus, the fitting portion 60a is clamped in cooperation with the nut portion 42. Since the plate 63 is fixed to the small diameter portion 22a of the piston rod 22 when the housing 23 is screwed to the piston rod 22, the partition wall cylinder 60 is prevented from falling off the housing 23.

  A seal ring 64 is interposed between the partition wall cylinder 60 and the valve disk 37, and the space between the partition wall cylinder 60 and the valve disk 37 is sealed. In this way, by sealing with the seal rings 62 and 64, even if there is radial play between the partition wall cylinder 60 and the valve disk 37 and between the partition wall cylinder 60 and the housing 23, sealing can be performed. This is possible, and the processing cost can be reduced because the partition cylinder 60, the valve disk 37 and the housing 23 do not require high processing accuracy.

  Thus, the partition cylinder 60 is mounted on the valve disk 37 and the housing 23, thereby forming a relief passage 61 partitioned from the lower chamber R2 as one working chamber on the inside thereof.

  In the shock absorber D 2, an annular spacer 65 having an outer diameter smaller than that of the one-side relief valve 33 is provided between the plate 63 and the one-side relief valve 33 so as not to hinder the bending of the one-side relief valve 33. The relief passage 41 provided in the shock absorber D1 and the notched spacer 38 communicating with the second passage and the through hole 40 provided in the piston rod 22 are eliminated.

  Therefore, in the case of the shock absorber D2, in order to connect the relief passage 61 to the second passage, the nut portion 42 of the housing 23 is provided with a through hole 42c that communicates the pressure chamber C1 and the relief passage 61, and this through hole 42c. The plate 63 is provided with a through hole 63a so that the through hole 42c and the through hole 63a are opposed to each other, and the relief passage 61 communicates with the other chamber 27 in the pressure chamber C1.

  Therefore, in the case of this shock absorber D2, the one side port 31 and the other side port 32 are communicated with the lower chamber R2 because the valve disk 37 is disposed in the lower chamber R2 as one working chamber, The relief passage 61, the through hole 63a, the through hole 42c, the other chamber 27, and the other side passage 25 are communicated with the upper chamber R1 as the other working chamber.

  Even in the shock absorber D2 configured as described above, when the piston speed is in the extremely low speed region and the low speed region, similarly to the shock absorbers D and D1, the frequency of vibration input to the shock absorber D2 is low. When the frequency is low, a large damping force is exhibited. On the other hand, when the frequency of vibration input to the shock absorber D2 is high, a small damping force is exhibited, thereby improving the riding comfort of the vehicle. it can.

  And even in this shock absorber D2, as with the shock absorbers D and D1, when the telescopic operation is performed at high speed, the one-side relief valve 33 or the other-side relief valve 34 opens, so that the liquid is Not only the one-side attenuation passage 21a and the other-side attenuation passage 21b as the first passage, but also from the upper chamber R1 to the lower chamber R2 or from the lower chamber R2 to the upper chamber via the one-side port 31 or the other-side port 32. It moves to R1, the damping force generated by the shock absorbers D and D1 is reduced, and does not increase to the value set by the specifications of the leaf valves V1 and V2.

  Therefore, even in the shock absorber D2 of the present embodiment, in a scene where the piston speed is high such that the vehicle gets over the large unevenness, it functions in the same manner as the shock absorbers D and D1 described above, and the damping force against the piston speed. The damping force can be reliably reduced by reducing the gradient of the vibration, so that the damping force stays high like a conventional shock absorber, and the effect of insulating the transmission of vibration from the axle to the vehicle body disappears. In the vehicle, the ride comfort in the vehicle can be improved, the speed damping force characteristics of the shock absorber D2 when contracting and extending can be set independently, and the degree of freedom of tuning Has improved dramatically, can reduce impact shock while supporting the car body firmly when turning, providing a supple but firm undercarriage to the vehicle It is possible.

  Further, in this embodiment, the notched spacer 38 for directly connecting the relief passage 61 to the other side passage 25 is not required, and the length in the axial direction is such that the amount of bending of the one side relief valve 33 can be secured. A spacer 65 having a height may be incorporated instead, and the axial distance between the valve disk 37 and the housing 23 in the vertical direction in FIG. 11 between the valve disk 37 and the housing 23 can be shortened. It is easy to secure the stroke length of the shock absorber D2.

  Even in the shock absorber D2, the valve disk shown in FIGS. 7 and 8 can be applied, and the partition cylinder 60 can be integrated with either the valve disk 37 or the housing 23. In addition, a configuration in which the relief passage 61 is directly communicated with the second passage without passing through the pressure chamber C1 may be employed, and it is natural that the advantages of providing the variable orifice 46 and the friction member 48 described above can be benefited. Is possible. Further, the inner diameter of the skirt 21d in the piston 21 is made larger than the outer diameter of the annular other-side relief valve 34 that directly faces the piston 21, and a part of the other-side relief valve 34 is inserted inside the skirt 21d. As a result, it becomes easy to secure the stroke length of the shock absorber D2, and a smooth stroke can be realized.

  Next, a description will be given of a shock absorber D3 as another modification of the specific shock absorber D1 described above. In the shock absorber D3 in this other modification, as shown in FIG. 12, the structure of the housing 70 is different from that of the shock absorber D1, and the partition cylinder 80 that divides the relief passage 81 in the housing 70 is provided. It is integrated. Even in the description of the shock absorber D3, for the sake of duplication of explanation, portions where the shock absorber D3 is different from the shock absorber D1 will be described in detail, and detailed description of the same portions as the shock absorber D1 will be omitted. .

  The housing 70 includes a ring-shaped nut portion 72 that is screwed into a screw portion 22 b provided at the tip of the piston rod 22, and a housing cylinder 73 that is suspended from the outer periphery of the nut portion 72 and accommodates a free piston 82. 71 and a cap 74 that is attached to the opening end 73c of the container 71 and closes the opening end 73c of the container 71, and the container 71 and the cap 74 are provided in the lower chamber R2 as one working chamber. The pressure chamber C2 is partitioned. The pressure chamber C2 is connected to the other chamber 84 communicated with the upper chamber R1 as the other working chamber by the free piston 82 via the other side passage 25 which is a part of the second passage, and one of the second passages. It is partitioned into a first chamber 83 communicated with a lower chamber R2 as one working chamber via a first side passage 24 that is a part.

  Even in the shock absorber D3 of this embodiment, as in the shock absorbers D1 and D2, by screwing the housing 70, the piston 21 as a partition member, the leaf valves V1, V2 as damping valves, The one-side relief valve 33, the other-side relief valve 34, and the valve disc 37 are fixed to the piston rod 22.

  The nut portion 72 includes a female screw 72 a provided on the inner peripheral side, and a through hole 72 b that communicates the inside and the outside of the housing 70. A plurality of notches 72c extending radially from the inner edge of the coil spring 30 as a spring element to the through hole 72b are provided at the end of the nut portion 72 on the other chamber 84 side at intervals in the circumferential direction. Thus, the through hole 72b is not blocked by the upper end of the coil spring 30 accommodated in the other chamber 84 in FIG.

  On the outer periphery of the upper end in FIG. 12, which is the end of the nut portion 72 on the valve disk 37 side, a partition cylinder 80 is provided that fits on the outer periphery of the valve disk 37 stacked on the piston 21 side as a partition member from the housing 70. Yes. When the partition cylinder 80 is fitted to the outer periphery of the valve disc 37, a space defined from the lower chamber R2 as one working chamber is formed between the valve disc 37 and the housing 70, and a relief passage 81 is formed in the space. Is formed.

  A seal ring 66 is interposed between the partition wall cylinder 80 and the valve disk 37, and the space between the partition wall cylinder 80 and the valve disk 37 is sealed. In this way, by sealing with the seal ring 66, it is possible to seal even if there is a radial play between the partition wall cylinder 80 and the valve disk 37. This eliminates the need for high processing accuracy, thereby reducing processing costs.

  Even in the shock absorber D3, as in the shock absorber D2, an annular spacer 65 having an outer diameter smaller than that of the one-side relief valve 33 is provided in the housing so as not to hinder the bending of the one-side relief valve 33. 70 is provided between the nut portion 72 and the one-side relief valve 33, and is provided in the relief rod 41 and the piston rod 22 that communicate with the relief passage 41 and the second passage provided in the shock absorber D1. The through-hole 40 is discarded.

  In the case of the shock absorber D3, the relief passage 81 is connected to the other passage 25 in the second passage through a through hole 72b provided in the nut portion 72. Accordingly, the one-side port 31 and the other-side port 32 have an upper chamber R1 as the other working chamber and a lower chamber R2 as the one working chamber via the relief passage 81, the through hole 72b, and the other-side passage 25. Communicate.

  On the other hand, the accommodating cylinder 73 is suspended from the outer periphery of the lower end of the nut portion 72 in FIG. 12, and the inner diameter is expanded from the middle in FIG. 12, and a stepped portion 73a is provided on the inner periphery. Furthermore, a gripping portion 73 b for gripping with a tightening tool (not shown) is provided on the outer periphery of the housing cylinder 73. The cross-sectional shape of the grip portion 73b described above is a shape that can be gripped by a tightening tool (not shown), and is, for example, a shape other than a true circle such as a two-sided width shape or a hexagonal shape according to the shape of the tightening tool. The The gripping portion 73b may be accessible from the outside with a tightening tool, and only needs to have an axial length that can be gripped with the tightening tool. In addition, the storage cylinder 73 is provided with a variable orifice 73d that allows the lower chamber R2 and the container 71 to communicate with each other.

  The cap 74 is integrated with the container 71 configured in this manner by caulking the opening end 73 c of the housing cylinder 73 in FIG. 12 from the outer peripheral side toward the outer periphery of the cap 74. The cap 74 has a disc shape with a convex portion 74a protruding inward of the container 71 at the center, and a fixed orifice 74b constituting a part of one side passage passing through the convex portion 74a is provided. In addition, a chamfer 74c is provided on the outer periphery of the end surface facing the lower chamber R2 on the side opposite to the container to promote plastic deformation by caulking of the housing cylinder 73. The shape of the cap 74 may be a disc shape without the convex portion 74a, but the end surface on which the chamfered portion 74c is installed can be easily identified without providing a gaze by providing the convex portion 74a. Therefore, it is possible to prevent the occurrence of assembly failure. Moreover, the convex part 74a can be fitted to the inner periphery of the coil spring 29 accommodated in the one chamber 83, and can be positioned, and the axial displacement of the coil spring 29 can be prevented.

  In the pressure chamber C2 formed by the container 71 and the cap 74, a free piston 82 is slidably inserted in a direction opposite to the above-described shock absorbers D1 and D2, and this free piston 82 is inserted. Thus, the inside of the pressure chamber C2 is divided into the other chamber 84 communicated with the upper chamber R1 by the other passage 25 and the one chamber 83 communicated with the lower chamber R2 by the fixed orifice 74b and the variable orifice 73d. The free piston 82 is provided on a sliding contact cylinder 82a that is in sliding contact with the inner periphery of the housing cylinder 73, a bottom 82b that closes an end of the sliding contact cylinder 82a on the nut portion side that is the upper end in FIG. 12, and a bottom 82b. A projecting portion 82c projecting toward the nut portion 72, an anti-bottom side annular groove 82d and a bottom side annular groove 82e provided in an axial direction on the outer periphery of the sliding contact cylinder 82a, and the bottom side annular groove 82e in sliding contact. A hole 82f communicating with the cylinder 82a is provided.

  And the friction member 48 is accommodated in the said bottom bottom annular groove 82d similarly to the buffer device D1. Therefore, when the free piston 82 is incorporated into the container 71, the friction member 48 does not pass through the variable orifice 73d formed in the housing cylinder 73, so that the friction member 48 can be reliably prevented from being damaged.

  Furthermore, when the upper end of the bottom piston 82 abuts the stepped portion 73 a formed on the inner periphery of the container 71 of the container 71, the free piston 82 is further restricted from moving upward in FIG. When the lower end in FIG. 12 of the contact tube 82a abuts on the upper end in FIG. 12 of the cap 74, further downward movement in FIG. 12 is restricted.

  The variable orifice 73d provided in the housing cylinder 73 is always opposed to the bottom annular groove 82e when the free piston 82 is elastically supported by the coil springs 29, 30 as spring elements and is in the neutral position. When communicating with the lower chamber R2 and the free piston 82 is displaced to the stroke end, that is, until the free piston 82 contacts the stepped portion 73a or the cap 74, the free piston 82 is completely overlapped with the outer periphery of the sliding cylinder 82a. It is supposed to be blocked. That is, in this case, the one-side passage in the second passage is composed of a bottom-side annular groove 82e, a hole 82f, a variable orifice 73d, and a fixed orifice 74b. In the figure, two variable orifices 73d are provided, but the number thereof is arbitrary, and the same applies to the number of fixed orifices 74b.

  That is, even in the case of the shock absorber D3, when the amount of displacement from the neutral position of the free piston 82 is an arbitrary amount of displacement, all the openings of the variable orifice 73d face the bottom-side annular groove 82e. Transitioning to the situation where the outer periphery of the sliding cylinder 82a begins to face, the flow area of the variable orifice 73d gradually begins to decrease, and the flow resistance in the one-side passage gradually increases. Therefore, the above-mentioned arbitrary displacement amount is set by setting the vertical width in the figure of the bottom side annular groove 82e and the opening position of the variable orifice 73d on the inner peripheral side of the housing cylinder 73. In this embodiment, as the amount of displacement of the free piston 82 increases, the flow passage area of the variable orifice 73d gradually decreases, and when the free piston 82 reaches the stroke end, the variable orifice 73d completely slides. The cylinder 82a is closed facing the cylinder 82a, the flow path resistance in the one-side passage is maximized, and the one chamber 83 is communicated with the lower chamber R2 only by the fixed orifice 74b.

  Although the shock absorber D3 is configured as described above, as in the shock absorbers D to D2, when the telescopic operation is performed at a high speed, the one side relief valve 33 or the other side relief valve 34 opens, so that the liquid Is not only the one-side attenuation passage 21a and the other-side attenuation passage 21b as the first passage, but also from the upper chamber R1 to the lower chamber R2 or from the lower chamber R2 via the one-side port 31 or the other-side port 32. It moves to the upper chamber R1, and the damping force generated by the shock absorber D3 is reduced and does not increase to the value set by the specifications of the leaf valves V1 and V2.

  Therefore, even in the shock absorber D3 of the present embodiment, in a situation where the piston speed is high such that the vehicle gets over the large unevenness, the same function as the shock absorbers D to D2 described above, and the damping force against the piston speed The damping force can be reliably reduced by reducing the gradient of the vibration, so that the damping force stays high like a conventional shock absorber, and the effect of insulating the transmission of vibration from the axle to the vehicle body disappears. In the vehicle, the ride comfort of the vehicle can be improved, the speed damping force characteristics of the shock absorber D3 when contracting and extending can be set independently, and the degree of tuning freedom Has improved dramatically, can reduce impact shock while supporting the car body firmly when turning, providing a supple but firm undercarriage to the vehicle It is possible.

  Furthermore, in this embodiment, the notched spacer 38 for directly connecting the relief passage 81 to the other side passage 25 is not required, and the length in the axial direction is such that the deflection amount of the one side relief valve 33 can be secured. A spacer 65 having a length may be incorporated instead, and the axial distance between the valve disk 37 and the housing 70 in the vertical direction in FIG. It is easy to secure the stroke length of the shock absorber D3.

  Even in the shock absorber D3, the valve disk shown in FIGS. 7 and 8 can be applied. The bulkhead cylinder 80 can be integrated with the valve disk 37, or both the valve disk 37 and the housing 70 can be integrated. It is possible to adopt a configuration in which the relief passage 81 is directly connected to the second passage without passing through the pressure chamber C2, and it is possible to adopt a configuration in which the relief passage 81 is communicated directly to the second passage. Of course, it is possible to benefit from the effect of providing the variable orifice 73d and the friction member 48. Further, the inner diameter of the skirt 21d in the piston 21 is made larger than the outer diameter of the annular other-side relief valve 34 that directly faces the piston 21, and a part of the other-side relief valve 34 is inserted inside the skirt 21d. As a result, the stroke length of the shock absorber D3 can be easily secured, and a smooth stroke can be realized.

  Further, in the case of this shock absorber D3, when the piston 21, leaf valves V1, V2, valve disc 37, one side relief valve 33 and the other side relief valve 34 are fixed to the piston rod 22, a container 71 constituting the housing 70 is provided. Has a gripping portion 73b that can be gripped by a tightening tool, and can directly apply a tightening torque to the nut portion 72 without using the cap 74 attached to the container 71. The tightening torque is applied to the cap 74. Therefore, no backlash occurs between the container 71 and the cap 74, and the generation of abnormal noise can be prevented.

  Since no tightening torque is applied to the cap 74, there is no need to provide grooves or irregularities on the outer periphery of the cap 74 to prevent rotation at the crimped portion, the structure of the cap 74 is simplified, and the number of processing steps is reduced. Since it can be reduced, the economy is also improved.

  Subsequently, the configuration of the shock absorber D4 in another example in which the shock absorber D is embodied will be shown and described.

  As shown in FIG. 13, the shock absorber D4 includes a valve disk 90 for one side relief valve and a valve disk 91 for the other side relief valve, and is buffered in that there are two valve disks. Different from the devices D1, D2, D3. Even in the description of the shock absorber D4, for the sake of overlapping explanation, portions different from the shock absorber D1 described above will be described in detail.

  In this shock absorber D4, when the shock absorber D1 has laminated the one-side relief valve 33 and the other-side relief valve 34 on the valve disc 37, the one-side relief valve 33 is laminated on the one-side valve disc 90, and the other-side valve. The other-side relief valve 34 is stacked on the disk 91, and these are assembled to the small-diameter portion 22 a of the piston rod 22, and the housing 23 is fixed to the piston rod 22 together with the piston 21 as a partition member.

  Specifically, the one side valve disc 90 is annular and is laminated and assembled on the outer periphery of the small diameter portion 22a of the piston rod 22 and below the leaf valve V2 as the other side damping valve in FIG. An annular window 90a formed at the non-piston side end which is the lower end in FIG. 13, a passage 90b which opens from the piston side end which is the upper end in FIG. 13 and communicates with the annular window 90a, and an inner periphery of the piston side end A cylindrical valve holding portion 90c that rises is provided. The one-side port 92 is constituted by an annular window 90a and a passage 90b, and the one-side port 92 is opened and closed by the one-side relief valve 33 stacked on the non-piston side end of the one-side valve disc 90. It has become.

  Further, when the one-side valve disc 90 is laminated to the lower side in FIG. 13 of the leaf valve V2 laminated on the lower chamber R2 side end of the piston 21 as a partition member, a valve holding portion 90c provided on the one-side valve disc 90 is provided. Comes into contact with the inner periphery of the leaf valve V2 to suppress the inner periphery of the leaf valve V2 and allow the outer end of the leaf valve V2 to bend while being fixed to the piston rod 22. Yes. The valve holding portion 90c is not integrated with the one-side valve disk 90, but is separated from the one-side valve disk 90 as a spacer and is interposed between the one-side valve disk 90 and the leaf valve V2. Also good.

  And the other side valve disc 91 is also annular, is the outer periphery of the small diameter portion 22a of the piston rod 22, and is laminated and assembled via an annular spacer 93 below the one side relief valve 33 in FIG. An annular window 91a formed at the non-piston side end which is the lower end in FIG. 13, a passage 91b which opens from the piston side end which is the upper end in FIG. 13 and communicates with the annular window 91a, and an outer periphery of the piston side end A partition cylinder 94 that rises and an annular groove 95 that is provided on the inner periphery and communicates with the passage 91b are configured. The other side port 96 is constituted by an annular window 91a and a passage 91b, and the other side port 96 is opened and closed by the other side relief valve 34 stacked on the opposite piston side end of the other side valve disk 91. It has become. In this case, the spacer 93 may be integrated with the other side valve disk 91, and the bent one side relief valve 33 interferes with the other side valve disk 91 while suppressing the inner periphery of the one side relief valve 33. I try not to let you.

  Further, as described above, when the other side valve disk 91 is laminated on the one side valve disk 90 via the one side relief valve 33 and the spacer 93, the partition wall cylinder 94 is fitted to the outer periphery of the one side valve disk 90. In cooperation with the one side valve disk 90 and the other side valve disk 91, a space defined from the lower chamber R2 as one working chamber is created, and a relief passage 97 is formed in the space. A seal ring may be interposed between the one-side valve disk 90 and the partition wall cylinder 94 in order to make the sealing performance perfect. The partition cylinder 94 may be integrated with the one-side valve disk 90 instead of the other-side valve disk 91.

  Further, when the other side valve disc 91 is assembled to the small diameter portion 22 a of the piston rod 22, an annular groove 95 provided on the inner periphery opens from the side portion of the small diameter portion 22 a of the piston rod 22 and communicates with the other side passage 25. Opposing the through hole 98, the relief passage 97 communicates with the upper chamber R1 as the other working chamber. The relief passage 97 faces the one side valve disc 90 and the other side valve disc 91 and communicates with the one side port 92 and the other side port 96. Accordingly, the one-side port 92 and the other-side port 96 communicate the upper chamber R1 and the lower chamber R2 via the relief passage 97, the through hole 98, and the other-side passage 25.

  In the shock absorber D4, a cylindrical valve restraining portion 42d protruding toward the other side valve disc 91 is provided on the inner periphery of the valve disc side end of the nut portion 42 in the housing 23 forming the pressure chamber C1. Thus, the inner periphery of the other side relief valve 34 can be set as a fixed end by bringing the valve holding portion 42d into contact with the inner periphery of the other side relief valve 34. Even in the valve holding portion 42d, it may be separated from the housing 23.

  Although the shock absorber D4 is configured as described above, as with the shock absorbers D to D3, when the telescopic operation is performed at high speed, the one-side relief valve 33 or the other-side relief valve 34 opens, so that the liquid Is not only from the one-side attenuation passage 21a and the other-side attenuation passage 21b as the first passage, but also from the upper chamber R1 to the lower chamber R2 or from the lower chamber R2 via the one-side port 92 or the other-side port 96. Moving to the upper chamber R1, the damping force generated by the shock absorber D4 is reduced and does not increase to the value set by the specifications of the leaf valves V1 and V2.

  Therefore, even in the shock absorber D4 of the present embodiment, in a scene where the piston speed becomes high so that the vehicle gets over the large unevenness, it functions in the same manner as the shock absorbers D to D3 described above, and the damping force against the piston speed. The damping force can be reliably reduced by reducing the gradient of the vibration, so that the damping force stays high like a conventional shock absorber, and the effect of insulating the transmission of vibration from the axle to the vehicle body disappears. In the vehicle, the ride comfort in the vehicle can be improved, the speed damping force characteristics of the shock absorber D4 when contracting and extending can be set independently, and the degree of freedom of tuning Has improved dramatically, can reduce impact shock while supporting the car body firmly when turning, providing a supple but firm undercarriage to the vehicle It is possible.

  Further, since the one-side port 92 and the other-side port 96 adopt a configuration in which the lower chamber R2 as one working chamber communicates with the upper chamber R1 as the other working chamber without passing through the pressure chamber C1, Since the operations of the side relief valve 33 and the other side relief valve 34 are less likely to affect the pressure in the one chamber 26 and the other chamber 27 in the pressure chamber C1, when the piston speed is lower than the low speed, the shock absorber D4 is aimed. Street frequency damping force characteristics can be generated.

Further, in the shock absorber D4 of this embodiment, the other side relief valve 34 is laminated on the anti-piston side surface as the anti-partition member side surface of the other side valve disk 91, and one of the pistons 21 as the partition member is provided. Since the structure is such that the leaf valve V2 as the other-side damping valve stacked on the side of the lower chamber R2 as the working chamber and the other-side relief valve 34 do not face each other, the shock absorber D4 extends to extend the other working chamber. Even if the liquid passes through the leaf valve V2 and flows into the lower chamber R2 as one working chamber from the upper chamber R1 as a jet, the jet does not directly hit the other side relief valve 34. The valve opening operation of the other side relief valve 34 is not adversely affected. Similarly, since the one-side relief valve 33 does not face the leaf valve V1 as the one-side damping valve, the liquid jet that has passed through the leaf valve V1 does not affect the one-side relief valve 33. Therefore, the stable operation of the one-side relief valve 33 and the other-side relief valve 34 is ensured, and a stable speed damping force characteristic can be obtained without the speed damping force characteristic varying depending on the expansion / contraction state of the shock absorber D4. Furthermore, the collision of the liquid jet that has passed through the one-side relief valve 33 and the liquid jet that has passed through the leaf valve V1 as the one-side damping valve and the liquid jet that has passed through the other-side relief valve 34 and the other-side damping valve as Collision of a jet of liquid that has passed through the leaf valve V2 can also be avoided, and a swoosh noise caused by the collision of the jet can be prevented. In the above description, the one-side valve disc 90 and the other-side valve disc 91 are installed in the lower chamber R2 as one working chamber, but are provided in the upper chamber R1 as the other working chamber. Alternatively, the one-side valve disk 90 and the other-side valve disk 91 may be installed in separate working chambers. Even in such a case, the one-side relief valve 33 is replaced with the one-side valve disk. 90 is laminated on the opposite end of the partition wall member so as not to face the one-side damping valve, and the other-side relief valve 34 is laminated on the opposite end of the other-side valve disk 91 so as not to face the other-side damping valve. By doing so, it is possible to obtain a stable speed damping force characteristic and an effect of preventing the generation of the swoosh sound. When it is not necessary to obtain the effect of stabilizing the speed damping force characteristics and preventing the generation of the swoosh noise, as shown in FIG. 14, the one side valve disc 90, the one side relief valve 33, the other side valve disc 91, and the other side It is also possible to assemble the relief valve 34 on the small-diameter portion 22a of the piston rod 22 in the upside down direction without losing the effect of the present invention. By the way, in the shock absorber D4 shown in FIG. 13, the relief passage 97 and the second passage are communicated with the passage 91b of the other side port 96 through the annular groove 95 provided on the inner periphery of the other side valve disk 91. The annular groove 95 is made to face the through hole 98 provided in the piston rod 22, but the other side valve disc 91 is, for example, as a modification of the shock absorber D4 shown in FIG. Is provided with a large-diameter portion 100 which is formed by setting the inner diameter of the non-piston side end to be larger than the outer diameter of the piston rod 22 and is opposed to the through hole 98, and a spacer 93 is laminated on the other valve disc 91. In order to maintain communication between the large-diameter portion 100 and the other-side port 96, a notch 101 that leads from the large-diameter portion 100 to the other-side port 96 is provided. It may be configured to communicate the passage 97 to the second passage.

  Even in the shock absorber D4 of this embodiment, the housing 70 described in the shock absorber D3 can be applied instead of the housing 23. In that case, the partition wall cylinder 80 is removed and applied. do it. Further, even in the shock absorber D4 of this embodiment, it is naturally possible to receive the benefits of providing the variable orifice 46 and the friction member 48 described above.

  Further, in the shock absorber D4, as shown in FIGS. 13 and 14, the inner diameter of the skirt 21d is set to be larger than the outer diameter of the valve disks 90 and 91 that directly face the piston 21, and the skirt 21d. Since a part of the valve discs 90 and 91 can be inserted inward, the stroke length of the shock absorber D4 can be ensured and a smooth stroke can be realized. In this case, if the cross-sectional area of the annular gap between the skirt 21d and the valve discs 90 and 91 is larger than the flow area of the one-side attenuation passage 21a and the flow area of the other-side attenuation passage 21b, Since the resistance given to the liquid flow by the annular gap between the skirt 21d and the valve discs 90 and 91 does not exceed the resistance given to the liquid flow by the one-side damping passage 21a and the other-side damping passage 21b, the piston as the partition member The frequency attenuation characteristic and the speed damping force characteristic as set in the one-side attenuation passage 21a and the other-side attenuation passage 21b provided in the member 21 can be obtained.

  Next, a description will be given of a shock absorber D5 as another modification of the above-described specific shock absorber D4. In the shock absorber D5, as shown in FIG. 15, the structures of the one side valve disk 110, the other side valve disk 111, and the partition cylinder 112 are different from those of the shock absorber D4. Even in the description of the shock absorber D4, for the sake of duplication of explanation, portions where the shock absorber D5 is different from the shock absorber D4 will be described in detail, and detailed description of the same portions as the shock absorber D4 will be omitted. .

  In the shock absorber D4, the bulkhead cylinder 94 is integrated with the one side valve disk 90 or the other side valve disk 91. However, in this shock absorber D5, the one side valve disk 110 and the other side valve disk 111 have the same shape. The partition cylinder 112 is fitted to the outer periphery of the one side valve disc 110 and the other side valve disc 111, and a space defined from one working chamber is formed between the one side valve disc 110 and the other side valve disc 111. The relief passage 116 is formed in the space.

  Specifically, both the one-side valve disc 110 and the other-side valve disc 111 are annular and are assembled to the outer periphery of the small-diameter portion 22a of the piston rod 22, and the anti-piston side serving as the lower end in FIG. Annular windows 110a and 111a formed at the ends, passages 110b and 111b that open from the piston side end that is the upper end in FIG. 15 and communicate with the annular windows 110a and 111a, and an annular shape that extends over the entire outer periphery. The projections 110c and 111c are provided.

  The one-side port 113 is constituted by an annular window 110a and a passage 110b, and the one-side port 113 is opened and closed by the one-side relief valve 33 stacked on the non-piston side end of the one-side valve disk 110. It has become.

  The other side port 114 is constituted by an annular window 111a and a passage 111b, and the other side port 114 is opened and closed by the other side relief valve 34 stacked on the opposite end of the other side valve disk 111. It is like that.

  The partition cylinder 112 is cylindrical and is fitted to the outer periphery of the one-side valve disk 110 and the other-side valve disk 111, and the annular protrusion 110 c of the one-side valve disk 110 and the annular shape of the other-side valve disk 111. The protrusion 111c prevents the one-side valve disc 110 and the other-side valve disc 111 from coming off. A seal ring may be provided between the partition cylinder 112 and the one-side valve disk 110, and between the partition cylinder 112 and the other-side valve disk 111. By fitting the partition cylinder 112 to the outer circumferences of the one side valve disk 110 and the other side valve disk 111 in this way, a partition is formed from one working chamber between the one side valve disk 110 and the other side valve disk 111. In addition, a relief passage 116 communicating with the one side port 113 and the other side port 114 is formed.

  Between the one-side relief valve and the other-side valve disk 111, a cylindrical notched spacer 115 having the same shape as the notched spacer 38 of the shock absorber D1 is interposed. Is opposed to the through hole 98 formed in the small diameter portion 22 a of the piston rod 22, and the relief passage 116 is connected to the second passage, specifically the other side passage 25 through the notch 115 a provided in the notched spacer 115. Communicated. Therefore, the one-side port 113 and the other-side port 114 are communicated with the lower chamber R2 as one working chamber, and via the relief passage 116, the notch 115a, the through hole 98, and the other-side passage 25 in the second passage. The other working chamber communicates with the upper chamber R1.

  Although the shock absorber D5 is configured as described above, as with the shock absorbers D to D4, when the telescopic operation is performed at a high speed, the one side relief valve 33 or the other side relief valve 34 opens, so that the liquid Is not only from the one side attenuation passage 21a and the other side attenuation passage 21b as the first passage, but also from the upper chamber R1 to the lower chamber R2 or from the lower chamber R2 via the one side port 113 or the other side port 114. It moves to the upper chamber R1, the damping force generated by the shock absorber D5 is reduced, and does not increase to the value set by the specifications of the leaf valves V1, V2.

  Therefore, even in the shock absorber D5 of the present embodiment, in a scene where the piston speed is high such that the vehicle gets over the large unevenness, it functions in the same manner as the shock absorbers D to D4 described above, and the damping force against the piston speed. The damping force can be reliably reduced by reducing the gradient of the vibration, so that the damping force stays high like a conventional shock absorber, and the effect of insulating the transmission of vibration from the axle to the vehicle body disappears. In the vehicle, the ride comfort in the vehicle can be improved, the speed damping force characteristics of the shock absorber D5 when contracting and extending can be set independently, and the degree of tuning freedom Has improved dramatically, can reduce impact shock while supporting the car body firmly when turning, providing a supple but firm undercarriage to the vehicle It is possible.

  Further, since the one-side port 113 and the other-side port 114 adopt a configuration in which the lower chamber R2 as one working chamber communicates with the upper chamber R1 as the other working chamber without passing through the pressure chamber C1, Since the operations of the side relief valve 33 and the other side relief valve 34 are less likely to affect the pressure in the one chamber 26 and the other chamber 27 in the pressure chamber C1, the piston D5 is aimed at when the piston speed is low or lower. Street frequency damping force characteristics can be generated.

  In the case of this embodiment, the one side valve disc 110 and the other side valve disc 111 have the same shape, so that the production cost can be reduced by sharing parts, and the notched spacer 115 is provided. Since the relief passage 116 can be connected to the second passage, the structure of the one-side valve disc 110 and the other-side valve disc 111 is simplified, and the one-side port 113 and the other-side port 114 are also arranged on the one-side valve disc. 110 and the other side valve disc 111 can be provided along the axial direction, so that the processing cost is reduced.

  Further, in the shock absorber D5 of this embodiment, as in the shock absorber D4 shown in FIG. 13, the other side laminated on the side of the lower chamber R2 as one working chamber of the piston 21 as the partition member. Since the structure is such that the leaf valve V2 as the damping valve and the other side relief valve 34 do not face each other, the shock absorber D5 extends and the liquid passes through the leaf valve V2 from the upper chamber R1 as the other working chamber. Even if the jet flows into the lower chamber R2 as one working chamber, the jet does not directly hit the other-side relief valve 34, and the jet has an adverse effect on the opening operation of the other-side relief valve 34. There is no. Similarly, since the one-side relief valve 33 does not face the leaf valve V1 as the one-side damping valve, the liquid jet that has passed through the leaf valve V1 does not affect the one-side relief valve 33. Therefore, stable operation of the one-side relief valve 33 and the other-side relief valve 34 is ensured, and a stable speed damping force characteristic can be obtained without the speed damping force characteristic varying depending on the expansion / contraction state of the shock absorber D5. Furthermore, the collision of the liquid jet that has passed through the one-side relief valve 33 and the liquid jet that has passed through the leaf valve V1 as the one-side damping valve and the liquid jet that has passed through the other-side relief valve 34 and the other-side damping valve as Collision of a jet of liquid that has passed through the leaf valve V2 can also be avoided, and a swoosh noise caused by the collision of the jet can be prevented. In the case where it is not necessary to stabilize the velocity damping force characteristic and prevent the generation of the squish noise, the one-side valve disc 110, the one-side relief valve 33, the other-side valve disc 111, and the other-side relief valve 34 are stacked. It is also possible to assemble the piston rod 22 to the small diameter portion 22a in the upside down direction, and the effect of the present invention is not lost.

  Even in the shock absorber D5 of this embodiment, the housing 70 described in the shock absorber D3 can be applied instead of the housing 23. In this case, the partition tube 80 is removed and applied. do it. Further, even in the shock absorber D5 of this embodiment, it is naturally possible to receive the benefits of providing the variable orifice 46 and the friction member 48 described above. Further, the inner diameter of the skirt 21d in the piston 21 is made larger than the outer diameter of the one-side valve disk 110 directly facing the piston 21, and a part of the one-side valve disk 110 is inserted inside the skirt 21d. Thus, it is easy to secure the stroke length of the shock absorber D5, and a smooth stroke can be realized.

  In the above description, one working chamber is the lower chamber R2 and the other working chamber is the upper chamber R1, but one working chamber is the upper chamber R1, and the other working chamber is the lower chamber R2. A valve disk or a housing may be provided in the chamber R1.

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

  The shock absorber of the present invention can be used for vehicle vibration control.

DESCRIPTION OF SYMBOLS 1,20 Cylinder 2,21 Piston 3 as a partition member First passage 4 Second passage 5,24 One side passage 5a Restriction 6,25 Other side passage 7,26,83 One chamber 8,27,84 Other chamber 9, 28, 82 Free piston 10 Spring element 11, 31, 92, 113 One side port 12, 32, 96, 114 The other side port 13, 33 One side relief valve 13a, 14a Valve body 13b, 14b Spring 13c, 14c Pilot passage 14 , 34 Other side relief valve 15, 23, 70 Housing 15a Hollow portion 16, 22 Piston rod 21a One side damping passage 21b as first passage The other side damping passage 22a as first passage Small diameter portion 22b in piston rod In piston rod Screw part 21c Disk part 21d in the piston as a partition member Skirts 28a and 82a in all pistons Sliding cylinders 28b and 82b in free pistons Bottoms 28c and 82c in free pistons Protruding portions 28d in free pistons Annular grooves 28e and 82f in free pistons Friction member receiving grooves in free pistons 29, 30 Coil springs 31a, 32a As spring elements 31b, 32b Inclined passages 31c, 32c Passage 35 Valve stopper 36 Spacer 37 Valve disc 37a Valve seat 38 Notched spacer 38a Notched spacer hole 38b Notched spacer 39 60, 80, 94, 112 Bulkhead cylinder 39a Hole 40, 98 in the bulkhead cylinder Through hole 41, 61, 81, 97, 116 Relief passage 42, 72 Nut portion 42a, 72a Screw portion 42b Small-diameter portions 42c and 72b in the nut portion 42d through hole 42d in the nut portion Valve restraining portion 43 in the nut portion 44 housing 44a tube 44b in the housing tube step 44c in the housing tube 44c bottom portions 45 and 74b in the housing tube fixed Orifice 46, 73d Variable orifice 48 Friction member 50, 52 Annular plate 51, 54 Through hole 60a Fitting portion 60b in partition tube Tube portion 62, 64, 66 in partition tube Seal ring 63 Plate 63a Through hole 65, 93 in plate 71 Container 72c Notch 73 in nut portion Housing tube 73a Stepped portion 73b in housing tube Holding portion 73c in housing tube Open end 74 in housing tube Cap 74a Convex portion 74c in cap Chamfered portion 82d in cap Free chamfered portion 82d Shaped groove 82e bottom annular grooves 90, 110 in free piston one side valve discs 90a, 110a annular windows 90b, 110b in one side valve discs passage 90c in one side valve discs valve restraining portions 91, 111 in one side valve discs Valve discs 91a and 111a Annular windows 91b and 111b on the other side valve disc A passage 95 on the other side valve disc An annular groove 100 on the other side valve disc A large-diameter portion 101 on the other side valve disc The notch 110c on the other side disc Annular projection 111c annular projection C on the other side valve disc C, C1, C2 pressure chamber D, D1, D2, D3, D4, D5 shock absorber F sliding partition G gas chamber R1 as the other working chamber Upper chamber R2 Lower chamber V as one working chamber Damping valve V1 Leaf valve V2 as one side damping valve Leaf valve as the other side damping valve

Claims (23)

A cylinder, a partition member that is slidably inserted into the cylinder and partitions the inside of the cylinder into two working chambers, a first passage and a second passage communicating the two working chambers, and a damping valve provided in the first passage And a pressure chamber provided in the middle of the second passage, a first chamber that is movably inserted into the pressure chamber and communicates with the one working chamber, and a second chamber that communicates with the other working chamber. In a shock absorber provided with a free piston that partitions and a spring element that generates an urging force that suppresses displacement of the free piston with respect to the pressure chamber, one side port that communicates the two working chambers, and the two working chambers. The other side port that communicates with each other, the one side relief valve that opens and closes the one side port using the pressure in one working chamber as a pilot pressure, and the other side relief that opens and closes the other side port using the pressure in the other working chamber as a pilot pressure Damping device, characterized in that provided between the valve. The shock absorber according to claim 1, wherein the one side port and the other side port communicate with the two working chambers through the second passage. The shock absorber according to claim 1 or 2, wherein the one-side port and the other-side port are directly communicated with the second passage to communicate the two working chambers. The shock absorber according to claim 1 or 2, wherein the one-side port and the other-side port are communicated with the second passage through the pressure chamber to communicate the two working chambers. A piston rod that is movably inserted into the cylinder and has one end connected to the partition member and a housing that forms the pressure chamber in one working chamber, and the second passage includes the one working chamber and the one working chamber A one-side passage that communicates with the chamber, and a second-side passage that is provided on the piston rod and communicates the other working chamber and the other chamber, and communicates the one-side port and the other-side port to the other-side passage. The shock absorber according to any one of claims 1 to 4, wherein the shock absorber is provided. A valve disc provided with the one side port and the other side port is provided, one side relief valve is laminated on one end side of the valve disc, and the other side relief valve is laminated on the other end side of the valve disc. The shock absorber according to any one of claims 1 to 5. The partition member and the valve disc are assembled to one end of the piston rod, and the partition member and the valve disc are connected to one end of the piston rod by screwing a housing forming the pressure chamber to one end of the piston rod. The shock absorber according to claim 6, wherein the shock absorber is fixed to the shock absorber. A partition cylinder is provided between the valve disk and the housing, and a relief passage is defined by the partition cylinder from the one working chamber, and the one side port and the other side port are connected through the relief passage. The shock absorber according to claim 6 or 7, wherein the shock absorber communicates with the other side passage. 9. The shock absorber according to claim 8, wherein the partition cylinder is integrated with one of the valve disk and the housing and is fitted to the other outer periphery of the valve disk and the housing. The partition member includes a disk portion having a first passage, and a cylindrical skirt that rises from the outer periphery of the disk portion toward the housing and faces the inner surface of the cylinder, and the inner diameter of the skirt is one side relief valve or the other side relief. The shock absorber according to any one of claims 6 to 9, wherein the shock absorber has a larger diameter than the outer diameter of the relief valve disposed on the partition member side of the valve and directly facing the partition member. A one-side valve disk having the one-side port and a second-side valve disk having the other-side port are provided, the one-side relief valve is stacked on the one-side valve disk, and the one-side valve disk has the above-mentioned 6. The shock absorber according to claim 1, wherein the other side relief valve is laminated. 12. The shock absorber according to claim 11, wherein the one side valve disk and the other side valve disk have the same shape. The partition member, the one-side valve disk and the other-side valve disk are assembled to one end of the piston rod, and the partition member by screwing a housing forming the pressure chamber to one end of the piston rod, The shock absorber according to claim 11 or 12, wherein the one-side valve disk and the other-side valve disk are fixed to one end of a piston rod. The first passage includes a one-side damping passage and the other-side damping passage provided in the partition member, respectively, and a damping valve is stacked on one side of the working chamber of the partition member to open and close the outlet end of the one-side damping passage. A side damping valve and a second side damping valve stacked on the side of the other working chamber of the partition wall member to open and close the outlet end of the other side damping passage, and the one side relief valve on the side surface of the one side valve disk opposite to the partition wall member 14. The shock absorber according to any one of claims 11 to 13, wherein the other side relief valve is laminated on a side surface of the opposite partition member of the other side valve disk. A disk space wall cylinder is provided between the one side valve disk and the other side valve disk, and a disk space relief passage partitioned from the one working chamber is formed by the disk space wall cylinder. The shock absorber according to any one of claims 11 to 14, wherein the one-side port and the other-side port are communicated with the other-side passage through a port. The disc space wall cylinder is integrated with one of the one-side valve disc and the other-side valve disc, and is fitted to the other outer periphery of the one-side valve disc and the other-side valve disc. The shock absorber according to claim 15, characterized in that: The said one side valve disk and the said other side valve disk are made into the same shape, provided the annular protrusion on the outer periphery, respectively, The omission of the said disk space | interval wall cylinder was prevented by these protrusions, The shock absorber described. The partition member includes a disk portion having a first passage, and a cylindrical skirt that rises from the outer periphery of the disk portion toward the housing and faces the inner surface of the cylinder, and the one-side valve disk and the other-side valve disk The shock absorber according to any one of claims 11 to 17, wherein the inner diameter of the skirt is larger than the outer diameter of the valve disk disposed on the partition member side and directly facing the partition member. The partition member includes a disk portion having a first passage, and a cylindrical skirt that rises from the outer periphery of the disk portion toward the housing and faces the inner surface of the cylinder, and the inner diameter of the skirt is one side relief valve or the other side relief. The shock absorber according to any one of claims 11 to 17, wherein the shock absorber has a larger diameter than an outer diameter of a relief valve disposed on a partition member side of the valve and directly facing the partition member. The housing includes a nut portion that is screwed to a tip end of a piston rod, and an accommodating cylinder that is suspended from the outer periphery of the nut portion and accommodates a free piston. The shock absorber according to 13, 14, 15, 16, 17, 18 or 19. The housing includes a container having a nut portion screwed to the tip of the piston rod, a housing cylinder suspended from the outer periphery of the nut portion and accommodating a free piston, and an opening end of the container mounted on the opening end of the container. And a cap that can be gripped by a tightening tool that applies a tightening torque to the container, and is provided on the outer periphery of the container. The shock absorber according to 15, 16, 17, 18 or 19. The shock absorber according to any one of claims 1 to 21, wherein a friction member that suppresses displacement of the free piston relative to the housing is provided between the housing forming the pressure chamber and the free piston. The free piston includes a sliding contact cylinder that is in sliding contact with the container cylinder of the container, a bottom that closes an end of the sliding contact cylinder on the nut portion side, and an anti-bottom side annular groove that is arranged in the axial direction on the outer periphery of the sliding contact cylinder. And a bottom-side annular groove communicating with the sliding contact cylinder, and an annular friction member mounted in the non-bottom-side annular groove, and the one-side passage in the second passage is a bottom-side annular groove of the free piston A variable orifice that is formed in the housing cylinder of the container and faces the bottom annular groove of the free piston when the free piston is in a neutral position, and communicates one working chamber to the one chamber via the bottom annular groove; The shock absorber according to claim 21 or 22, wherein the shock absorber is formed by a fixed orifice that is formed in the cap and communicates between one working chamber and the one chamber.

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