JP6565442B2 - Cylinder device - Google Patents

Description

  The present invention relates to a cylinder device that is installed in a building structure such as a building or a factory and is suitably used for buffering vibrations such as earthquakes.

  In general, a cylinder device such as an oil damper configured to use the resistance of hydraulic fluid passing through an orifice as a piston moves in a cylinder as a device for damping and buffering vibration in a building structure, mechanical equipment, etc. Are known. This type of prior art employs a so-called double rod type cylinder device in which a long piston rod extending on both sides in the axial direction is provided for a piston that defines a cylinder in two chambers. For this reason, the two chambers in the cylinder have the advantage that the volume difference of the rod cross-section integral does not occur when the piston rod is displaced in one direction and the other direction, and the generated damping force in both strokes can be made uniform. (For example, refer to Patent Document 1).

JP-A-1-320341

  By the way, there is also a so-called single rod type cylinder device in which one end side of a piston rod is fixed to a piston in a cylinder and the other end side of the piston rod protrudes outside the cylinder. In the case of the single rod type, there is a problem that it is difficult to equalize the generated damping force in both strokes because a volume difference of the rod cross-section integral occurs between the extension stroke and the reduction stroke of the piston rod.

  The present invention has been made in view of the above-described problems of the prior art, and an object of the present invention is to provide a cylinder device capable of equalizing the generated damping force in the expansion stroke and the reduction stroke of the piston rod. There is to do.

In order to solve the above-described problems, a cylinder device according to the present invention includes a cylinder in which a working fluid is sealed, and a piston that is slidably fitted in the cylinder and defines the inside of the cylinder into one side chamber and another side chamber. A piston rod having one end connected to the piston and the other end extending to the outside of the cylinder, a volume compensation mechanism for compensating for a volume change generated in the one side chamber and the other side chamber due to the movement of the piston, and the piston The hydraulic fluid in the one-side chamber is provided with the volume compensation until the piston slides and displaces by a predetermined dimension from the neutral position to the one side in the axial direction. a first one-way passage to prevent the flow of reverse allowed to flow toward the mechanism, provided at a distance from each other in the axial direction from the neutral position of the piston to the other side, the piston from the neutral position A second one-way passage portion until only slidably displaced a predetermined distance to the other side in the direction that prevents the flow of reverse allowing the hydraulic fluid of the other side chamber flows toward the volume compensation mechanism Are provided.

  According to the present invention, even in a so-called single rod type cylinder device, it is possible to equalize the generated damping force in the expansion / contraction stroke.

It is a longitudinal section showing a hydraulic shock absorber as a cylinder device by an embodiment of the invention. It is a longitudinal cross-sectional view which shows the state which the piston rod in FIG. 1 displaced to the expansion | extension direction. It is a longitudinal cross-sectional view which shows the state which the piston rod in FIG. 1 displaced to the reduction | decrease direction. It is a characteristic diagram which shows the relationship between the displacement of a piston rod, and generated damping force. It is a longitudinal cross-sectional view which shows the hydraulic shock absorber as a cylinder apparatus by the 1st modification. It is a longitudinal cross-sectional view which shows the hydraulic shock absorber as a cylinder apparatus by the 2nd modification.

  Hereinafter, the case where the cylinder device according to the embodiment of the present invention is applied to a hydraulic shock absorber used for vibration damping of a building or the like will be described in detail with reference to the accompanying drawings.

  In the figure, the hydraulic shock absorber 1 shows a typical example of a cylinder device. The hydraulic shock absorber 1 includes a bottomed cylindrical cylinder 2 that forms an outer shell, a rod guide 3, a piston 4, a piston rod 7, a volume compensation mechanism 8, and first and second one-way passage portions 15 described later. , 16 and so on. A working fluid as a working fluid is sealed in the cylinder 2. The working fluid is not limited to working oil and oil, and for example, water mixed with additives can be used.

  The cylinder 2 of the hydraulic shock absorber 1 has a closed end 2A closed at one end (right end in FIG. 1) by a bottom cap (not shown) and the other end is an open end 2B. A rod guide 3 is fitted and provided on the opening end 2 </ b> B side of the cylinder 2. The rod guide 3 is formed in a stepped cylindrical shape, and guides a piston rod 7 described later on the inner peripheral side thereof so as to be slidable in the axial direction.

  The piston 4 is a movable partition wall that is slidably fitted (inserted) into the cylinder 2. The piston 4 is divided into two chambers, a bottom side chamber A as one side chamber and a rod side chamber B as another side chamber. The piston 4 is provided with oil passages 5A and 5B capable of communicating the bottom side chamber A and the rod side chamber B and damping force generation mechanisms 6A and 6B on the extension side and the reduction side.

  The extension-side damping force generation mechanism 6A is configured as a relief valve, for example, by a disk valve or the like. When the piston 4 slides and displaces in the cylinder 2 in the direction of the rod side chamber B in the extension stroke of the piston rod 7, the extension-side damping force generating mechanism 6A gives a resistance force to the working fluid flowing through the oil passage 5A. To generate an extensional damping force. On the other hand, the reduction-side damping force generation mechanism 6B is configured as a relief valve by a disk valve or the like, for example. When the piston 4 slides and displaces in the cylinder 2 in the direction of the bottom side chamber A in the reduction stroke of the piston rod 7, the reduction-side damping force generation mechanism 6B gives a resistance force to the working fluid flowing through the oil passage 5B. The damping force on the reduction side is generated.

  One end of the piston rod 7 is connected to the piston 4 in the cylinder 2. The other end side of the piston rod 7 projects so as to extend and contract so as to extend to the outside of the cylinder 2 via the rod guide 3 and the like. The protruding end side of the piston rod 7 is swingably attached to a beam (not shown) of a building structure, for example. On the other hand, the closed end 2A of the cylinder 2 is provided with a mounting portion (not shown) such as a mounting eye connected to other beams or the like of the building structure.

  The hydraulic shock absorber 1 includes a volume compensation mechanism 8 that compensates for volume changes that occur in the bottom side chamber A and the rod side chamber B due to the movement of the piston 4 (ie, sliding displacement). The volume compensation mechanism 8 is disposed outside the cylinder 2 (for example, radially outside), and a reservoir 9 in which hydraulic fluid is stored, and the hydraulic fluid in the reservoir 9 is sucked into the bottom chamber A in the cylinder 2. The suction valve 10 on the bottom side that allows the flow in the reverse direction and prevents the reverse flow, and allows the hydraulic fluid in the reservoir 9 to flow into the rod side chamber B in the cylinder 2 to flow in the reverse direction. And a suction valve 11 on the rod side that prevents the flow of gas.

  Here, the suction valves 10 and 11 are opened and closed so that when the piston 4 is slid in the axial direction in the cylinder 2, the inside of the cylinder 2 is always kept filled with the working fluid. That is, when the piston 4 slides and displaces in the cylinder 2 in the direction of the rod side chamber B in the extension stroke of the piston rod 7, the bottom side suction valve 10 opens and the working fluid in the reservoir 9 enters the bottom side chamber A. And sucked. On the other hand, when the piston 4 slides and displaces in the cylinder 2 in the direction of the bottom side chamber A in the reduction stroke of the piston rod 7, the rod side suction valve 11 opens and the hydraulic fluid in the reservoir 9 moves to the rod side chamber B. And sucked.

  Between the rod side chamber B and the reservoir 9 in the cylinder 2, an extension side damping valve 12 is provided in parallel with the rod side suction valve 11. As shown in FIG. 2, the extension side damping valve 12 is disposed in the rod side chamber B when the piston 4 in the cylinder 2 is slidably displaced by a predetermined dimension L or more from the neutral position C in the axial direction (rod extension side). The valve opens when the pressure exceeds a predetermined valve opening pressure. At this time, the expansion side damping valve 12 gives a throttle resistance to the hydraulic fluid flowing from the rod side chamber B toward the reservoir 9 and generates a predetermined damping force in a direction to suppress the extension operation of the piston rod 7.

  On the other hand, a contraction side damping valve 13 is provided between the bottom side chamber A in the cylinder 2 and the reservoir 9 in parallel with the bottom side suction valve 10. As shown in FIG. 3, the compression side damping valve 13 is disposed in the bottom side chamber A when the piston 4 in the cylinder 2 is slidably displaced from the neutral position C in the axial direction (rod reduction side) by a predetermined dimension L or more. The valve opens when the pressure exceeds a predetermined valve opening pressure. At this time, the contraction-side damping valve 13 gives a throttling resistance to the working fluid flowing from the bottom-side chamber A toward the reservoir 9 and generates a predetermined damping force in a direction that suppresses the contraction operation of the piston rod 7.

  On the inner peripheral surface of the cylinder 2, a plurality of bypass grooves 14 extending to both sides in the axial direction with respect to the neutral position C of the piston 4 shown in FIG. 1 are provided. These bypass grooves 14 are arranged on the inner peripheral surface of the cylinder 2 with a space in the circumferential direction, and the entire length extends in the axial direction with a length of, for example, a dimension 2L. That is, each bypass groove 14 has a dimension L (a total dimension of 2L) in which the end 14A on one side in the axial direction and the end 14B on the other side in the axial direction are left and right (axial direction) with respect to the neutral position C of the piston 4. ). Each bypass groove 14 bypasses the piston 4 and connects the bottom side chamber A and the rod side chamber B to each other when the piston 4 is in a sliding range less than a dimension L (ie, ± L) from the neutral position C. It is a groove to communicate.

  The hydraulic shock absorber 1 includes a first one-way passage portion 15 including the end portion 14A side of the bypass groove 14 and a second one-way passage including the end portion 14B side of the bypass groove 14. Part 16. The first one-way passage portion 15 is provided such that the end portion 14A side of the bypass groove 14 is spaced apart from the neutral position C of the piston 4 by a predetermined dimension L in the axial direction (in the direction of the bottom side chamber A). The hydraulic fluid is allowed to flow toward the reservoir 9 of the volume compensation mechanism 8 and the reverse flow is prevented. The second one-way passage portion 16 is provided such that the end portion 14B side of the bypass groove 14 is spaced apart from the neutral position C of the piston 4 by a predetermined dimension L in the axial direction (in the direction of the rod side chamber B). The hydraulic fluid is allowed to flow toward the reservoir 9 of the volume compensation mechanism 8 and the reverse flow is prevented.

  The first one-way passage portion 15 is provided in the middle of the communication passage 17, for example, a portion of the bypass groove 14 on the one end portion 14 </ b> A side, a communication passage 17 that connects a midway portion of the bypass groove 14 to the reservoir 9. The check valve 18 is configured to allow the working fluid to flow from the bypass groove 14 toward the reservoir 9 and prevent a reverse flow. The second one-way passage portion 16 includes a portion on the other end portion 14B side of the bypass groove 14, and a communication passage 17 and a check valve 18 that are used in common with the first one-way passage portion 15. Has been.

  The first and second one-way passage portions 15 and 16 are passages joined to each other on the connection point side with the communication passage 17 by the bypass groove 14. For this reason, when the piston 4 is within the sliding range less than the dimension L from the neutral position C, the first and second one-way passage portions 15 and 16 (bypass groove 14) bypass the piston 4 and bottom. The side chamber A and the rod side chamber B are communicated with each other. However, when the piston 4 is slid and displaced from the neutral position C to the dimension L or more in the extension stroke of the piston rod 7, the end 14B side of the bypass groove 14 is connected to the rod side chamber B by the piston 4 as shown in FIG. Communication is cut off. Further, in the reduction stroke of the piston rod 7, for example, as shown in FIG. 3, the end portion 14 </ b> A side of the bypass groove 14 is disconnected from the bottom chamber A by the piston 4.

  A characteristic line 19 shown in FIG. 4 shows that when the piston rod 7 of the hydraulic shock absorber 1 is displaced from the neutral position (for example, the neutral position C shown in FIG. 1) to the expansion side and the contraction side, It represents the damping force characteristics to be generated. Of the characteristic line 19, characteristic line portions 19A and 19C are damping force characteristics when the piston 4 is displaced from the neutral position C to the expansion side and the contraction side within a range less than the dimension L. Of the characteristic line 19, characteristic line portions 19B and 19D are damping force characteristics when the piston 4 is displaced from the neutral position C to the expansion side and the contraction side within the range of the dimension L or more. The dimension L from the neutral position C of the piston 4 is a dimension that is appropriately determined according to the installation location of the hydraulic shock absorber 1 and the like, and is also a design value determined based on the test data and the like so far.

  The hydraulic shock absorber 1 as a cylinder device according to the present embodiment has the above-described configuration. Next, the operation thereof will be described.

  The cylinder 2 of the hydraulic shock absorber 1 is connected at its closed end 2A side to a beam or the like of a building structure via a mounting portion (not shown) such as a mounting eye. Further, the protruding end side of the piston rod 7 is swingably attached to another beam or the like of the building structure. Thereby, for example, when vibration occurs in the building structure due to an earthquake or the like, the piston rod 7 extends in the axial direction from the cylinder 2 or contracts in the axial direction into the cylinder 2 to It can be buffered to damp vibrations.

  That is, when the piston rod 7 is in the extension stroke, when the piston 4 is displaced from the neutral position C within a range less than the dimension L, the bottom side chamber A and the rod side chamber B in the cylinder 2 are the first and second ones. The direction passage portions 15 and 16 (a plurality of bypass grooves 14) bypass the piston 4 and communicate with each other. The second one-way passage portion 16 is configured such that the end portion 14B side of the bypass groove 14 communicates with the inside of the rod side chamber B so that the hydraulic fluid in the rod side chamber B is directed to the reservoir 9 of the volume compensation mechanism 8. Allowed to circulate through. Further, the suction valve 10 on the bottom side of the volume compensation mechanism 8 compensates for the hydraulic fluid in the reservoir 9 being sucked into the bottom side chamber A as the piston rod 7 extends.

  For this reason, when the piston 4 is displaced from the neutral position C to the rod extension side within a range less than the dimension L, a large pressure difference does not occur between the rod side chamber B and the bottom side chamber A in the cylinder 2. The damping force generating mechanism 6A on the extension side of the piston 4 and the extension side damping valve 12 do not substantially generate a damping force. As a result, the hydraulic shock absorber 1 generates a relatively small damping force like the characteristic line portion 19A of the characteristic line 19 shown in FIG. This is a damping force due to, for example, the flow resistance of the hydraulic fluid flowing through each bypass groove 14 and the communication passage 17.

  Next, as shown in FIG. 2, when the piston 4 is displaced by the dimension L or more from the neutral position C to the extension side in the extension stroke of the piston rod 7, the end 14 </ b> B side of the bypass groove 14 is blocked from the rod side chamber B by the piston 4. Thus, in the rod side chamber B in the cylinder 2, the communication between the bottom side chamber A and the reservoir 9 is cut off. On the other hand, the suction valve 10 on the bottom side of the volume compensation mechanism 8 compensates for the working fluid in the reservoir 9 being sucked into the bottom side chamber A as the piston rod 7 extends.

  For this reason, when the piston 4 slides and displaces from the neutral position C to the rod extension side by a dimension L or more, the pressure in the rod side chamber B rises in the cylinder 2 and a large pressure is generated between the rod side chamber B and the bottom side chamber A. A difference occurs. As a result, when the pressure in the rod side chamber B exceeds a predetermined valve opening pressure, the extension side damping valve 12 is opened, and a throttle resistance is given to the working fluid flowing from the rod side chamber B toward the reservoir 9. A predetermined damping force is generated in a direction to suppress the extension operation of the piston rod 7.

  The damping force generation mechanism 6A on the extension side of the piston 4 opens when the pressure difference between the rod side chamber B and the bottom side chamber A exceeds a predetermined relief setting pressure, and opens the oil passage 5A of the piston 4. A throttle force is given to the hydraulic fluid flowing from the rod side chamber B toward the bottom side chamber A, and a predetermined damping force is generated in a direction to suppress the extension operation of the piston rod 7.

  As a result, like the characteristic line portion 19B in the characteristic line 19 shown in FIG. 4, the hydraulic shock absorber 1 can generate a large damping force so as to suppress the expansion operation of the piston rod 7, and the piston rod 7 is subjected to the stroke on the expansion side. It can be suppressed to extend to the end. During this time, the rod side suction valve 11 is closed and the check valve 18 is kept closed. However, when the bottom side suction valve 10 is opened, the hydraulic fluid in the reservoir 9 is supplied to the bottom of the cylinder 2. The side chamber A can be replenished.

  On the other hand, when the piston rod 7 is in the reduction stroke, when the piston 4 is displaced within the range less than the dimension L from the neutral position C, the bottom side chamber A and the rod side chamber B in the cylinder 2 are the first and second ones. The direction passage portions 15 and 16 (a plurality of bypass grooves 14) bypass the piston 4 and communicate with each other. The first one-way passage portion 15 is configured such that the end portion 14 </ b> A side of the bypass groove 14 communicates with the bottom chamber A so that the hydraulic fluid in the bottom chamber A is directed toward the reservoir 9 of the volume compensation mechanism 8. Allowed to circulate through. Further, the rod side suction valve 11 of the volume compensation mechanism 8 compensates for the hydraulic fluid in the reservoir 9 being sucked into the rod side chamber B as the piston rod 7 is contracted.

  For this reason, when the piston 4 is displaced from the neutral position C to the rod reduction side within a range of less than the dimension L, a large pressure difference does not occur between the bottom side chamber A and the rod side chamber B in the cylinder 2, The damping force generation mechanism 6B on the reduction side of the piston 4 and the compression side damping valve 13 do not substantially generate a damping force. As a result, the hydraulic shock absorber 1 generates a relatively small damping force like the characteristic line portion 19C of the characteristic line 19 shown in FIG. This is a damping force due to, for example, the flow resistance of the hydraulic fluid flowing through each bypass groove 14 and the communication passage 17.

  Next, as shown in FIG. 3, when the piston 4 is displaced from the neutral position C to the reduction side by a dimension L or more in the reduction stroke of the piston rod 7, the end 14 </ b> A side of the bypass groove 14 is blocked from the bottom side chamber A by the piston 4. Thus, the communication between the rod side chamber B and the reservoir 9 is cut off in the bottom side chamber A in the cylinder 2. On the other hand, the rod side suction valve 11 of the volume compensation mechanism 8 compensates for the hydraulic fluid in the reservoir 9 being sucked into the rod side chamber B as the piston rod 7 is contracted.

  For this reason, when the piston 4 slides and displaces from the neutral position C to the rod reduction side by a dimension L or more, the pressure in the bottom side chamber A rises in the cylinder 2 and a large pressure is generated between the bottom side chamber A and the rod side chamber B. A difference occurs. As a result, when the pressure in the bottom side chamber A exceeds a predetermined valve opening pressure, the compression side damping valve 13 is opened, and a throttle resistance is given to the working fluid flowing from the bottom side chamber A toward the reservoir 9. A predetermined damping force is generated in a direction that suppresses the reduction operation of the piston rod 7.

  Further, the reduction force generation mechanism 6B on the reduction side of the piston 4 opens when the pressure difference between the bottom side chamber A and the rod side chamber B exceeds a predetermined relief setting pressure, and opens the oil passage 5B of the piston 4. A throttle resistance is given to the working fluid flowing from the bottom side chamber A toward the rod side chamber B, and a predetermined damping force is generated in a direction that suppresses the reduction operation of the piston rod 7.

  As a result, like the characteristic line portion 19D of the characteristic line 19 shown in FIG. 4, the hydraulic shock absorber 1 can generate a large damping force so as to suppress the contraction operation of the piston rod 7, and the piston rod 7 can move toward the contraction side. It is possible to suppress the shrinkage to the end. During this time, the suction valve 10 on the bottom side is closed and the check valve 18 is also kept closed. However, when the suction valve 11 on the rod side is opened, the hydraulic fluid in the reservoir 9 is supplied to the rod in the cylinder 2. The side chamber B can be replenished.

  Thus, according to the present embodiment, when external vibration is applied between the closed end 2A of the cylinder 2 and the protruding end of the piston rod 7 due to the earthquake motion of the building structure or the like, the piston 4 becomes neutral. It is displaced from the position C to the expansion side and the contraction side. However, when the piston 4 is displaced to the expansion side or the contraction side within the range where the displacement amount is less than the dimension L from the neutral position C, the damping force characteristic of the hydraulic shock absorber 1 is expressed by the characteristic line portions 19A and 19C. In addition, the damping force region can be set, and the damping force on the expansion side and the contraction side can be set to an equal magnitude.

  Here, the hydraulic shock absorber 1 is a so-called single rod type cylinder device in which one end of the piston rod 7 is fixed to the piston 4 and the other end protrudes out of the cylinder 2. A volume difference of (entrance volume of the piston rod 7) is generated. However, the hydraulic shock absorber 1 is disposed outside the cylinder 2 and allows the working fluid to be stored therein, and allows the working fluid in the reservoir 9 to flow into the cylinder 2 so as to flow in the reverse direction. A volume compensation mechanism 8 including a suction valve 10 and 11 on the bottom side and the rod side for blocking the flow is provided.

  In addition, the hydraulic shock absorber 1 is provided at a predetermined distance L from the neutral position C of the piston 4 on the rod reduction side, and the hydraulic fluid in the bottom side chamber A flows toward the reservoir 9 of the volume compensation mechanism 8. A first one-way passage portion 15 including a bypass groove 14 that permits reverse flow and prevents reverse flow, and is provided in a rod-side chamber B spaced apart from the neutral position C of the piston 4 by a predetermined dimension L on the rod extension side. And a second one-way passage portion 16 including a bypass groove 14 that allows the hydraulic fluid to flow toward the reservoir 9 of the volume compensation mechanism 8 and prevents a reverse flow.

  Therefore, while the piston 4 is displaced in the vicinity of the neutral position (that is, displaced from the neutral position C to the rod extension side and the reduction side within a range less than the dimension L), the bottom side chamber A and the rod side chamber B within the cylinder 2. A large pressure difference does not occur between the hydraulic shock absorber 1 and the hydraulic shock absorber 1 with a relatively small damping force, such as the characteristic line portions 19A and 19C of the characteristic line 19 shown in FIG. 14 and the flow resistance of the hydraulic fluid flowing through the communication passage 17 can be generated.

  Thus, even in the single rod type hydraulic shock absorber 1 in which the volume difference of the rod cross-section integral occurs between the expansion stroke and the reduction stroke of the piston rod 7, the volume compensation mechanism 8 and the first and second one-way passage portions are provided. By adopting 15, 16, it is possible to equalize the generated damping force on the expansion side and the contraction side (that is, the generated damping force in both strokes), and suppress variations in the generated damping force due to the volume difference. Can do.

  Moreover, since the hydraulic shock absorber 1 is a so-called single rod type cylinder device in which one end of the piston rod 7 is fixed to the piston 4 and the other end side protrudes outside the cylinder 2, it is compared with a so-called double rod type cylinder device. Thus, the overall length can be shortened, and the whole can be made compact and light and compact. Thereby, the hydraulic shock absorber 1 can be easily installed even in a small installation place such as a narrow corner or a small building which is a corner of a building structure, and the versatility thereof can be enhanced.

  In the above embodiment, the case where the first and second one-way passage portions 15 and 16 are constituted by the bypass groove 14, the communication passage 17, and the check valve 18 has been described as an example. However, the present invention is not limited to this. For example, as in the first modification shown in FIG. 5, the first one-way passage 22 configured to include the first bypass 21 and the second bypass It is good also as a structure provided with the 2nd one way passage part 24 comprised including the path | route 23. FIG.

  Here, the first bypass passage 21 is connected to the bottom side chamber A at a position spaced apart by a predetermined dimension L in the axial direction from the neutral position C of the piston 4 shown in FIG. An annular groove 21A opened on the inner peripheral surface and a liquid passage 21B having one end communicating with the groove 21A and the other end communicating with a communication passage 25 described later. The second bypass passage 23 has an inner peripheral surface of the cylinder 2 so as to communicate with the rod side chamber B at a position spaced apart from the neutral position C of the piston 4 shown in FIG. And a liquid passage 23B having one end communicating with the concave groove 23A and the other end communicating with a communication passage 25 described later.

  In the first modification shown in FIG. 5, the first one-way passage portion 22 includes a first bypass passage 21, a communication passage 25 that connects the first bypass passage 21 to the reservoir 9, and a communication passage, for example. 25, and a check valve 26 that allows the working fluid to flow from the first bypass passage 21 toward the reservoir 9 and prevents a reverse flow. The second one-way passage portion 24 includes a second bypass passage 23, and the communication passage 25 and the check valve 26 that are used in common with the first one-way passage portion 22.

  The concave grooves 21A and 23A of the first and second bypass passages 21 and 23 are formed as annular grooves extending on the inner peripheral surface of the cylinder 2 over the entire circumference (or a part in the circumferential direction) as shown in FIG. be able to. The liquid passages 21B and 23B of the first and second bypass passages 21 and 23 are passages that merge with each other on the leading end side (connection point side with the communication passage 25). For this reason, when the piston 4 is in the sliding range less than the dimension L from the neutral position C, the first and second bypass passages 21 and 23 bypass the piston 4 and the bottom side chamber A and the rod side chamber B Communicate with each other.

  However, when the piston 4 is slid and displaced from the neutral position C to the dimension L or more in the extension stroke of the piston rod 7, the communication between the concave groove 23 </ b> A and the rod side chamber B is interrupted by the piston 4. Further, in the reduction stroke of the piston rod 7, the communication between the concave groove 21 </ b> A and the bottom side chamber A is cut off by the piston 4. Therefore, even in such a first modification, it is possible to obtain the same effect as that of the above-described embodiment.

  Moreover, you may comprise the 1st, 2nd one-way channel | path parts 31 and 35 like the 2nd modification shown, for example in FIG. The first one-way passage portion 31 includes a concave groove 32 provided on the inner peripheral surface of the cylinder 2 in the same manner as the annular concave groove 21A described in the first modification, and one end portion of the concave groove 32. The other end of the communication is connected to the reservoir 9 and the communication passage 33 is provided in the middle of the communication passage 33, for example, allowing the working fluid to flow from the concave groove 32 toward the reservoir 9 and preventing the reverse flow. And a check valve 34. The second one-way passage portion 35 includes a concave groove 36 provided on the inner peripheral surface of the cylinder 2 in the same manner as the annular concave groove 23 </ b> A described in the first modified example, and one end portion formed in the concave groove 36. The other end of the communication is connected to the reservoir 9, a communication passage 37 having a passage length equal to that of the communication passage 33, and a working fluid is provided toward the reservoir 9 from the concave groove 36 provided in the middle of the communication passage 37, for example. It is constituted by a check valve 38 that allows circulation and prevents reverse flow. Even in the second modified example, the same effect as that of the above-described embodiment can be obtained.

  Furthermore, in the said embodiment, the hydraulic shock absorber 1 which attenuate | damps vibrations, such as a building structure, was mentioned as the representative example of the cylinder apparatus, and was demonstrated. However, the present invention is not limited to this, and can also be applied to a shock absorber such as a vibration damping oil damper, a dashpot, or the like used for machine equipment in a factory. Furthermore, the present invention may be applied to a cylinder device used for a shock absorber of an automobile or the like.

  Next, the invention included in the embodiment will be described. According to the present invention, the first one-way passage portion communicates with the one-side chamber until the piston slides and displaces by a predetermined dimension from the neutral position to one side in the axial direction. The second one-way passage portion communicates with the other chamber until the piston slides and displaces by a predetermined dimension from the neutral position to the other side in the axial direction. In this case, the piston is cut off from the other chamber by the piston.

  Further, according to the present invention, the hydraulic fluid flows from the one-way passage portion toward the volume compensation mechanism until the piston passes through the first and second one-way passage portions from the neutral position. By being discharged, the piston extends until it passes from the neutral position to the position of the first and second one-way passage portions (that is, the range less than the dimension L in the vicinity of the neutral position C). It is set as the structure which makes equal the damping force of a stroke and a contraction stroke. Thereby, the generated damping force on the expansion side and the contraction side (that is, the generated damping force in both strokes) can be equalized, and variations in the generated damping force due to the volume difference of the rod cross-section integral can be suppressed.

1 Hydraulic shock absorber (cylinder device)
2 cylinder 3 rod guide 4 piston 6A, 6B damping force generation mechanism 7 piston rod 8 volume compensation mechanism 9 reservoir 10, 11 suction valve 12 expansion side damping valve 13 contraction side damping valve 14 bypass groove 15, 22, 31 first one Direction passage portion 16, 24, 35 Second one-way passage portion 17, 25, 33, 37 Communication passage 18, 26, 34, 38 Check valve 21 First bypass passage 21A, 23A, 32, 36 Concave groove 23 Second bypass path A Bottom side chamber (one side chamber)
B Rod side chamber (other side chamber)

Claims (3)

A cylinder filled with hydraulic fluid;
A piston that is slidably fitted in the cylinder, and that defines the inside of the cylinder into one side chamber and another side chamber;
A piston rod having one end connected to the piston and the other end extending to the outside of the cylinder;
A volume compensation mechanism for compensating for a volume change generated in the one-side chamber and the other-side chamber by the movement of the piston;
The piston is provided so as to be axially separated from the neutral position to one side, and the hydraulic fluid in the one-side chamber is moved until the piston is slid by a predetermined dimension from the neutral position to one side in the axial direction. A first one-way passage section that allows flow towards the volume compensation mechanism and prevents reverse flow;
The hydraulic fluid in the other side chamber is provided so as to be axially spaced from the neutral position of the piston to the other side until the piston slides and displaces by a predetermined dimension from the neutral position to the other side of the axial direction. A second one-way passage section that allows flow towards the volume compensation mechanism and prevents reverse flow;
A cylinder device comprising: The first one-way passage portion communicates with the one-side chamber until the piston is slidably displaced from the neutral position to one side in the axial direction by a predetermined dimension, and when the piston is further displaced, the one-side chamber is It is configured to be blocked from
The second one-way passage portion communicates with the other side chamber until the piston slides and displaces by a predetermined dimension from the neutral position to the other side in the axial direction. The cylinder device according to claim 1, wherein the cylinder device is configured to be cut off from the cylinder.   Until the piston passes the position of the first and second one-way passages from the neutral position, the hydraulic fluid is discharged from the respective one-way passages toward the volume compensation mechanism, The damping force of the extension stroke and the contraction stroke is equalized between the neutral position and the passage of the first and second one-way passage portions. Cylinder device.

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