JP6522451B2 - Fluid pressure cylinder - Google Patents

Description

  The present invention relates to a fluid pressure cylinder.

  In the patent document 1, a passage extending from the working chamber to the port, the opening and the passage are communicated, and the working chamber is operated to the fitting portion of the first covering member which covers the cylinder tube and closes the end face opening. A hydraulic cylinder is disclosed which is formed with a throttle hole which serves to restrict the flow of fluid and discharge it towards the port, wherein a cushion ring is provided on the piston rod adjacent to the piston.

  In this hydraulic cylinder, when the piston rod moves in the direction to discharge the working fluid in the working chamber, the cushion ring is fitted in the enlarged diameter hole near its movement end and serves to close the enlarged diameter hole. As a result, the working fluid in the working chamber is discharged from the opening to the port through the throttling hole with a restricted flow rate, and a cushioning action is imparted at the end of movement of the piston rod.

JP, 2001-82415, A

  In the fluid pressure cylinder disclosed in Patent Document 1, when adjusting the cushioning performance, it is necessary to remove the first covering member from the cylinder tube and adjust the diameter of the throttle hole. However, removing the first covering member every time the cushion performance is adjusted is troublesome.

  The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a fluid pressure cylinder capable of easily adjusting cushioning performance.

A first invention is a fluid pressure cylinder, and a piston rod inserted into the cylinder tube, an annular cushion bearing provided on the piston rod, and an approach of the cushion bearing provided on the cylinder tube near the stroke end of the piston rod And a cushion that provides resistance to the flow of working fluid that is formed between the cushion bearing and the receptacle when the cushion bearing enters inside the receptacle near the stroke end of the piston rod The cushion adjustment unit includes a passage, a plurality of bypass passages provided in the receiving unit and bypassing the cushion passage, and a cushion adjustment unit that selectively switches the opening and closing of the plurality of bypass passages. A plurality of adjustment holes communicating with each and a plurality of adjustment holes And having been a plurality of switching member which is accommodated to open or close the bypass passage, the.
According to a second aspect of the present invention, the switching member includes an opening bolt for fully opening the bypass passage, and a closing bolt for completely closing the bypass passage, the switching member housed in the adjustment hole being the closing bolt and the opening bolt Switching between the two, selectively switching the opening and closing of the bypass passage.

In the first and second inventions, near the stroke end, the working fluid passes through the cushion passage and the open bypass passage. By selectively switching the opening and closing of the plurality of bypass passages by the cushion adjustment unit and changing the number of bypass passages to be opened, the total flow passage area through which the working fluid passes is adjusted. Therefore, the cushioning performance can be adjusted without disassembling the fluid pressure cylinder.

In the third invention, the cylinder tube has an opening at one end, the receiving portion is provided in the cylinder head that seals the opening of the cylinder tube, and the cylinder tube and the cylinder head are aligned in the circumferential direction A plurality of fastening bolts are connected, and a plurality of adjustment holes are provided between circumferential directions of the plurality of fastening bolts.

According to the third aspect of the present invention, more bypass passages opened and closed by the switching member accommodated in the adjustment hole can be provided, so that the adjustable range of the cushioning performance of the fluid pressure cylinder can be enlarged.

The fourth invention further includes a piston which divides the inside of the cylinder tube into two fluid pressure chambers, and the bypass passage communicates with the first bypass passage communicating with one of the fluid pressure chambers and the first bypass passage through the adjustment hole. And the switching member is brought into contact with the opening of the second bypass passage to the adjustment hole to close the bypass passage.

  According to the present invention, the cushioning performance of the fluid pressure cylinder can be easily adjusted.

It is a sectional view of a fluid pressure cylinder concerning an embodiment of the present invention. It is a top view of a fluid pressure cylinder concerning an embodiment of the present invention. It is a sectional view showing the closure bolt of the fluid pressure cylinder concerning the embodiment of the present invention. It is a sectional view showing the opening bolt of the fluid pressure cylinder concerning the embodiment of the present invention. It is a sectional view showing the 1st modification of the fluid pressure cylinder concerning the embodiment of the present invention. It is sectional drawing which shows the 2nd modification of the fluid pressure cylinder which concerns on embodiment of this invention.

  Hereinafter, a fluid pressure cylinder according to an embodiment of the present invention will be described with reference to the drawings. Below, the case where a fluid pressure cylinder is hydraulic cylinder 100 which drives hydraulic fluid as a hydraulic fluid is explained.

  As shown in FIG. 1, the hydraulic cylinder 100 is connected to the cylindrical cylinder tube 10, the piston rod 20 inserted into the cylinder tube 10, and the tip of the piston rod 20, and along the inner circumferential surface of the cylinder tube 10. The piston 30 includes a sliding piston 30 and an annular cushion bearing 40 provided on the outer periphery of the piston rod 20.

  The inside of the cylinder tube 10 is divided by the piston 30 into two fluid pressure chambers, a rod side chamber 1 and an opposite rod side chamber 2. The hydraulic cylinder 100 is telescopically operated by hydraulic pressure guided from a hydraulic source (hydraulic fluid pressure source) to the rod side chamber 1 or the rod side chamber 2. A seal member 31 seals between the inner periphery of the cylinder tube 10 and the outer periphery of the piston 30. As a result, the communication between the rod side chamber 1 and the non-rod side chamber 2 is interrupted between the inner periphery of the cylinder tube 10 and the outer periphery of the piston 30.

  The cylinder tube 10 is provided with a cylindrical cylinder head 50 for sealing the opening 10A at one end and for slidably supporting the piston rod 20. The cylinder head 50 has a receiving portion 51 that allows the cushion bearing 40 to enter near the extension stroke end of the piston rod 20. Inside the cylinder tube 10, a part of the receiving portion 51 is inserted. The cylinder head 50 is fastened to the cylinder tube 10 via a plurality of fastening bolts 53 aligned in the circumferential direction, as shown in FIGS. 1 and 2. In FIG. 2, the piston rod 20 is not shown.

  As shown in FIG. 1, a bush 55, a sub seal 56, a main seal 57, and a dust seal 58 are interposed on the inner periphery of the cylinder head 50.

  The sliding contact of the bush 55 with the outer peripheral surface of the piston rod 20 supports the piston rod 20 to move in the axial direction of the cylinder tube 10.

  The cylinder head 50 is formed with a supply / discharge port 3 communicating with the rod side chamber 1 through an annular groove 4 formed on the inner peripheral surface. The hydraulic oil is supplied and discharged to the rod side chamber 1 through the supply and discharge port 3.

  The piston rod 20 has a main body portion 21 slidably contacting the inner periphery of the cylinder head 50, a small diameter portion 22 formed to have a smaller outer diameter than the main body portion 21, and an annular shape formed between the main body portion 21 and the small diameter portion 22. It has a step portion 23 and a screw portion 24 formed at the tip of the piston rod 20 and to which the piston 30 is fastened.

  The piston 30 is screwed into the screw portion 24 of the piston rod 20 and is fastened to the piston rod 20 by a predetermined clamping force.

  The cushion bearing 40 is provided on the outer periphery of the small diameter portion 22 of the piston rod 20. The inner diameter of the cushion bearing 40 is larger than the outer diameter of the small diameter portion 22 of the piston rod 20 and smaller than the outer diameter of the main portion 21 of the piston rod 20. The cushion bearing 40 is sandwiched by the stepped portion 23 of the piston rod 20 and the end surface 30 A of the piston 30.

  The outer diameter of the cushion bearing 40 is larger than the outer diameter of the main body portion 21 of the piston rod 20 and smaller than the inner diameter of the receiving portion 51. Thereby, the cushion bearing 40 enters inside the receiving portion 51 near the extension stroke end of the piston rod 20. The cushion bearing 40 enters the inside of the receiving portion 51 to form the cushion passage 5 between the cushion bearing 40 and the receiving portion 51. Resistance is applied to the flow of hydraulic fluid passing through the cushion passage 5. When the hydraulic oil passes through the cushion passage 5, a cushion pressure acts on the rod side chamber 1. As a result, in the hydraulic cylinder 100, a cushioning action is exerted in which the extension speed is reduced near the extension stroke end.

  Further, the hydraulic cylinder 100 includes a plurality of bypass passages 60 provided in the receiving portion 51 of the cylinder head 50 and bypassing the cushion passage 5, and a cushion adjustment unit 70 selectively switching the opening and closing of the plurality of bypass passages 60; Further comprising

  The bypass passage 60 bypasses the cushion passage 5 and communicates the rod side chamber 1 with the supply / discharge port 3 through the annular groove 4. That is, the bypass passage 60 guides a part of the hydraulic oil in the rod side chamber 1 to the supply and discharge port 3 without passing the cushion passage 5. The plurality of bypass passages 60 are provided independently of each other without communicating with each other, and are respectively disposed between the circumferential directions of the annularly arranged fastening bolts 53 (see FIG. 2). The plurality of bypass passages 60 are all formed in the same shape. The flow of the hydraulic fluid passing through the bypass passage 60 is given resistance in accordance with the minimum cross-sectional area of the bypass passage 60 (hereinafter simply referred to as “the cross-sectional area of the bypass passage 60”).

  As shown in FIGS. 3 and 4, the cushion adjustment unit 70 is accommodated in a plurality of adjustment holes 71 provided separately from each of the plurality of bypass passages 60 and in the plurality of adjustment holes 71 to open the bypass passage 60. Or a switching bolt as a plurality of switching members to be closed.

  The plurality of adjustment holes 71 are provided to open at the outer peripheral surface of the cylinder head 50. Similar to the bypass passage 60, the plurality of adjustment holes 71 are also disposed between the circumferential direction of the annularly arranged fastening bolts 53 (see FIG. 2). By providing the adjustment hole 71 in communication with the bypass passage 60, the bypass passage 60 communicates with the first bypass passage 61 opened to the rod side chamber 1 and the first bypass passage 61 through the adjustment hole 71 and the annular groove 4. And a second bypass passage 62 that opens to the In other words, a part of the adjustment hole 71 functions as a part of the bypass passage 60. In the hydraulic cylinder 100, the cross-sectional area of the second bypass passage 62 corresponds to the minimum cross-sectional area of the bypass passage 60.

  As the switching bolt housed in the adjustment hole 71, a closing bolt 75 (see FIG. 3) for closing the bypass passage 60 in a state housed in the adjustment hole 71 and a length shorter than the closing bolt 75 are accommodated in the adjustment hole 71 Two types are used: an open bolt 76 (see FIG. 4) which opens the bypass passage 60 in the state where the valve is installed. One of the closing bolt 75 and the opening bolt 76 is accommodated in the plurality of adjustment holes 71.

  As shown in FIG. 3, the closing bolt 75 has a bolt head 75A, an adjusting screw portion 75B screwed into the adjusting hole 71, and a cylindrical portion 75C provided at the tip of the adjusting screw portion 75B. The closure bolt 75 is accommodated over the entire length of the adjustment hole 71.

  The cylindrical portion 75C is provided with a seal member 77 that closes a gap between the outer periphery of the cylindrical portion 75C and the inner periphery of the adjustment hole 71. The seal member 77 is provided between the first bypass passage 61 and the second bypass passage 62. When the closing bolt 75 is accommodated in the adjustment hole 71, the cylindrical portion 75C is disposed between the first bypass passage 61 and the second bypass passage 62, and the communication between the two is interrupted. Further, by providing the seal member 77 on the outer periphery of the cylindrical portion 75C, communication between the first bypass passage 61 and the second bypass passage 62 through a gap between the outer periphery of the cylindrical portion 75C and the inner periphery of the adjustment hole 71. Is also blocked. As a result, the bypass passage 60 is closed, and the flow of hydraulic fluid through the bypass passage 60 is completely shut off. The sealing member 77 is not limited to the outer periphery of the cylindrical portion 75C, and may be provided between the end face of the cylindrical portion 75C and the bottom of the adjustment hole 71.

  As shown in FIG. 4, the opening bolt 76 has a bolt head 76A and an adjusting screw 76B screwed into the adjusting hole 71, but does not have a cylindrical portion 75C like the closing bolt 75. That is, the open bolt 76 is formed to a length that does not reach the bypass passage 60. Thus, the bypass passage 60 is not closed when the open bolt 76 is accommodated in the adjustment hole 71, and the flow of hydraulic oil through the bypass passage 60 is permitted.

  In this manner, the opening and closing of the bypass passage 60 can be selectively switched depending on whether the adjustment bolt 71 is accommodated in the adjustment hole 71 or the opening bolt 76 is accommodated.

  Next, the operation of the hydraulic cylinder 100 will be described.

  When the hydraulic pressure source communicates with the rod side chamber 1 and the tank (not shown) communicates with the opposite rod side chamber 2, the hydraulic fluid is supplied to the rod side chamber and the hydraulic fluid in the opposite rod side chamber is discharged to the tank. Thus, the hydraulic cylinder 100 is contracted.

  When the hydraulic pressure source communicates with the opposite rod side chamber 2 and the tank communicates with the rod side chamber 1, the hydraulic fluid is supplied to the opposite rod side chamber 2 and the hydraulic fluid in the rod side chamber 1 is discharged to the tank. For this reason, the hydraulic cylinder 100 operates to extend.

  When the piston rod 20 is moved near the end of the extension stroke as shown in FIG. 1 by the extension operation of the hydraulic cylinder 100, the cushion bearing 40 enters the inside of the receiving portion 51, and the outer peripheral surface of the cushion bearing 40 and the receiving portion 51 The cushion passage 5 is formed by the inner circumferential surface.

  The hydraulic oil in the rod side chamber 1 is led to the inlet / outlet 3 through the cushion passage 5 and the open bypass passage 60 and discharged from the rod side chamber 1. Because the flow of hydraulic fluid passing through the cushion passage 5 and the bypass passage 60 is resisted, the rod side chamber 1 is cushioned according to the resistance applied by the cushion passage 5 and the resistance applied by the bypass passage 60 Pressure acts. Thus, the cushioning action near the extension stroke end of the piston rod 20 is exhibited.

  Specifically, when the closing bolt 75 is accommodated in all the adjustment holes 71 and all of the plurality of bypass passages 60 are closed, the hydraulic oil in the rod side chamber 1 is discharged only through the cushion passage 5 . That is, when all of the plurality of bypass passages 60 are closed, the total flow passage area of the flow passage (hereinafter referred to as “discharge flow passage”) through which the hydraulic oil discharged from the rod side chamber 1 passes is It corresponds to the cross-sectional area of the cushion passage 5. Therefore, in this case, the flow of the hydraulic fluid is given resistance according to the cross-sectional area of the cushion passage 5, and a cushion pressure is generated according to the given resistance. In this state, the resistance applied to the hydraulic fluid is the largest, and the highest cushion pressure is generated.

  When a part of the plurality of bypass passages 60 is opened, the hydraulic oil in the rod side chamber 1 is discharged through the cushion passage 5 and a part of the bypass passages 60 opened. In this case, the total flow passage area of the discharge flow passage corresponds to the sum of the cross sectional area of the open bypass passage 60 and the cross sectional area of the cushion passage 5. Therefore, the flow of the hydraulic oil discharged from the rod side chamber 1 is given a resistance according to the sum of the cross sectional areas of the bypass passage 60 and the cushion passage 5 to be opened, and a cushion pressure according to the applied resistance is generated. Do.

  When the opening bolts 76 are accommodated in all the adjustment holes 71 and all of the plurality of bypass passages 60 are opened, the hydraulic oil in the rod side chamber 1 is discharged through the cushion passage 5 and all of the plurality of bypass passages 60. Therefore, the total flow passage area of the discharge flow passage corresponds to the total of the cross sectional area of the plurality of bypass passages 60 and the cross sectional area of the cushion passage 5. The flow of hydraulic fluid discharged from the rod side chamber 1 is given resistance according to the sum of the cross-sectional areas of all of the plurality of bypass passages 60 and the cushion passage 5, and cushion pressure is generated according to the applied resistance. Do. In this case, the resistance applied to the hydraulic fluid is the smallest, and the smallest cushion pressure is generated.

  As described above, the cushion pressure generated near the end of the extension stroke is generated according to the sum of the cross-sectional areas of the bypass passage 60 and the cushion passage 5 which are opened. Therefore, when the operator changes the type of the switching bolt accommodated in the adjustment hole 71 and changes the number of bypass passages 60 to be opened, the total passage cross-sectional area of the discharge passage is adjusted. Therefore, it is not necessary to remove the cylinder head 50 each time the cushion performance is adjusted, and the cushion performance can be easily adjusted.

  Further, in the hydraulic cylinder 100, the cushioning performance is adjusted by selectively switching the opening and closing of the plurality of bypass passages 60. Therefore, the cushioning performance is not continuous by opening or closing one bypass passage 60. , Change gradually. Therefore, in the hydraulic cylinder 100, the same cushioning performance is exhibited if the number of bypass passages 60 to be opened, in other words, the sum of the cross-sectional areas of the bypass passages 60 to be opened is the same. As described above, in the hydraulic cylinder 100, cushioning performance is achieved with high repeatability by selectively switching between opening and closing of the plurality of bypass passages 60 so that the sum of the cross-sectional areas of the opened bypass passages 60 becomes the same. It can be adjusted.

  The cushioning performance of the hydraulic cylinder 100 is adjusted according to the operating conditions of the hydraulic cylinder 100 such as the hydraulic pressure supplied to the hydraulic cylinder 100 and the load driven by the hydraulic cylinder 100. Since the hydraulic cylinder 100 selectively switches the opening and closing of the plurality of bypass passages 60, the cross-sectional area of the cushion passage 5 is obtained by multiplying the number of bypass passages 60 to be opened by the cross-sectional area of the bypass passage 60. By adding, it is possible to easily obtain the total flow area of the discharge flow channel. Therefore, it is possible to easily obtain the total flow passage area that exhibits the optimum cushioning performance adjusted in accordance with the operating conditions of the hydraulic cylinder 100. By accumulating the information of the optimum total flow passage area thus obtained together with the operating conditions, it can be used as basic information at the time of development and design of the hydraulic cylinder 100. That is, the total flow passage cross-sectional area of the discharge flow passage that exhibits the optimum cushioning performance of the hydraulic cylinder 100 used under the new operating condition can be predicted and determined based on the accumulated information.

  Next, a modification of the present embodiment will be described.

  In the above embodiment, the plurality of bypass passages 60 are all formed in the same shape. Alternatively, the plurality of bypass passages 60 may have different shapes, and a plurality of types of bypass passages 60 having different cross-sectional areas may be provided. In this case, marks such as markings may be provided so that bypass passages 60 having different cross-sectional areas can be identified.

  Further, in the above embodiment, the tip end of the closing bolt 75 is formed as a cylindrical portion 75C, and the seal member 77 is provided on the outer periphery of the cylindrical portion 75C, whereby communication between the first bypass passage 61 and the second bypass passage 62 is achieved. Completely shut off. If the communication between the first bypass passage 61 and the second bypass passage 62 through a slight gap between the closing bolt 75 and the adjustment hole 71 does not affect the cushioning performance, the sealing member 77 may not be provided.

  In addition, the closure bolt 75 may be formed in any shape as long as it blocks the communication between the first bypass passage 61 and the second bypass passage 62.

  For example, as shown in FIG. 5, a spherical portion 75D is provided at the tip of the cylindrical portion 75C of the closing bolt 75, and the spherical portion 75D is pressed toward the opening of the second bypass passage 62 to the adjustment hole 71. The bypass passage 61 and the second bypass passage 62 may be shut off.

  Alternatively, a tapered surface 75E may be formed at the tip of the cylindrical portion 75C of the closing bolt 75, and the opening of the second bypass passage 62 to the adjustment hole 71 may be sealed by the tapered surface 75E. In this case, as shown in FIG. 6, the sealability can be improved by forming the bottom of the adjustment hole 71 on the tapered surface 71A corresponding to the tapered surface 75E of the closing bolt 75.

  Further, in the above embodiment, the cushion bearing 40 is sandwiched by the piston rod 20 and the piston 30. Instead of this, the cushion bearing 40 is provided with a gap between it and the outer periphery of the piston rod 20, and can be slightly moved axially between the step 23 of the piston rod 20 and the end surface 30A of the piston 30. It may be a so-called floating support provided in

  According to the above embodiment, the following effects can be obtained.

  In the hydraulic cylinder 100, the opening and closing of the plurality of bypass passages 60 are selectively switched by replacing the switching bolt of the cushion adjusting unit 70, and the number of bypass passages 60 to be opened is changed. The area is adjusted. Therefore, the cushioning performance of the hydraulic cylinder 100 can be adjusted without disassembling the hydraulic cylinder 100 by removing the cylinder head 50. Therefore, the cushioning performance of the hydraulic cylinder 100 can be easily adjusted.

  Further, in order to adjust cushion performance by selectively switching the opening and closing of the plurality of bypass passages 60, the hydraulic cylinder 100 opens and closes the bypass passage 60 so that the total cross sectional area of the opened bypass passages 60 becomes the same. By switching, the cushioning performance can be adjusted with high reproducibility.

  Further, since the plurality of bypass passages 60 are respectively provided in the circumferential direction of the plurality of fastening bolts 53 connecting the cylinder head 50 and the cylinder tube 10, more bypass passages 60 may be provided in the cylinder head 50. it can. Therefore, the adjustable range of the cushioning performance of the hydraulic cylinder 100 can be enlarged.

  Hereinafter, the configuration, operation, and effects of the embodiment of the present invention will be collectively described.

  The hydraulic cylinder 100 includes a cylinder tube 10, a piston rod 20 inserted into the cylinder tube 10, an annular cushion bearing 40 provided on the piston rod 20, and a cushion near the stroke end of the piston rod 20 provided on the cylinder tube 10. When the cushion bearing 40 enters the inside of the receiving portion 51 near the stroke end of the piston rod 20, the receiving portion 51 which allows the entry of the bearing 40 and is formed and passed between the cushion bearing 40 and the receiving portion 51 A cushion adjustment unit that selectively switches the opening and closing of the cushion passage 5 that provides resistance to the flow of hydraulic fluid, the plurality of bypass passages 60 provided in the receiving unit 51 and bypassing the cushion passage 5, and the plurality of bypass passages 60 With 70, cushion adjustment 70 are a plurality of adjustment holes 71 communicating with each of the plurality of bypass passages 60, and a plurality of switching bolts respectively accommodated in the plurality of adjustment holes 71 to open or close the bypass passage 60 (closing bolt 75 and opening bolt 76 And.

  In this configuration, near the stroke end, the hydraulic oil passes through the cushion passage 5 and the open bypass passage 60. By opening and closing the plurality of bypass passages 60 selectively by the cushion adjustment unit 70 and changing the number of bypass passages 60 to be opened, the total flow passage area through which the hydraulic oil passes is adjusted. Therefore, the cushioning performance can be adjusted without disassembling the hydraulic cylinder 100. Therefore, the cushioning performance of the hydraulic cylinder 100 can be easily adjusted.

  Further, the hydraulic cylinder 100 has a cylinder head 50 in which the cylinder tube 10 seals the opening 10A at one end and the receiving portion 51 is provided, and the cylinder tube 10 and the cylinder head 50 are aligned in the circumferential direction. The plurality of adjustment holes 71 are provided between the plurality of fastening bolts 53 in the circumferential direction.

  According to this configuration, it is possible to provide more bypass passages 60 opened and closed by the switching bolt accommodated in the adjustment hole 71, and therefore, the range in which the cushioning performance of the hydraulic cylinder 100 can be adjusted can be enlarged.

  Further, in the hydraulic cylinder 100, the piston 30 divides the inside of the cylinder tube 10 into two fluid pressure chambers (the rod side chamber 1 and the rod side chamber 2), and the bypass passage 60 communicates with the rod side chamber 1 a first bypass passage. 61 and a second bypass passage 62 communicating with the first bypass passage 61 through the adjustment hole 71, and the switching bolt (closing bolt 75) abuts on the opening of the second bypass passage 62 to the adjustment hole 71 Causes the bypass passage 60 to be closed.

  As mentioned above, although the embodiment of the present invention was described, the above-mentioned embodiment showed only a part of application example of the present invention, and in the meaning of limiting the technical scope of the present invention to the concrete composition of the above-mentioned embodiment. Absent.

  100 ... hydraulic cylinder (fluid pressure cylinder), 5 ... cushion passage, 10 ... cylinder tube, 10 A ... opening, 20 ... piston rod, 30 ... piston, 40 ... cushion bearing, 50 ... cylinder head, 51 ... receiving part, 53 ... fastening bolt, 60 ... bypass passage, 70 ... cushion adjustment part, 71 ... adjustment hole, 75 ... closing bolt (switching member), 76 ... open connection bolt (switching member)

Claims (4)

Cylinder tube,
A piston rod inserted into the cylinder tube;
An annular cushion bearing provided on the piston rod;
A receptacle provided on the cylinder tube for allowing entry of the cushion bearing near the stroke end of the piston rod;
A cushion passage that provides resistance to the flow of working fluid formed between the cushion bearing and the receiving portion when the cushion bearing enters the inside of the receiving portion near the stroke end of the piston rod; ,
A plurality of bypass passages provided in the receptacle and bypassing the cushion passage;
A cushion adjustment unit that selectively switches the opening and closing of each of the plurality of bypass passages;
The cushion adjustment unit is
A plurality of adjustment holes communicating with each of the plurality of bypass passages;
And a plurality of switching members respectively accommodated in the plurality of adjustment holes to fully open or fully close each of the plurality of bypass passages. The switching member includes an opening bolt that fully opens the bypass passage, and a closing bolt that completely closes the bypass passage.
The fluid according to claim 1, wherein the opening and closing of the bypass passage is selectively switched by exchanging the switching member accommodated in the adjustment hole between the closing bolt and the opening bolt. Cylinder. The cylinder tube has an opening at one end,
The receiving portion is provided to a cylinder head sealing the opening of the cylinder tube,
The cylinder tube and the cylinder head are connected by a plurality of fastening bolts arranged in the circumferential direction,
The fluid pressure cylinder according to claim 1 or 2 , wherein the plurality of adjustment holes are provided in the circumferential direction of the plurality of fastening bolts. The apparatus further comprises a piston that divides the inside of the cylinder tube into two fluid pressure chambers,
The bypass passage is
A first bypass passage communicating with one of the fluid pressure chambers;
And a second bypass passage communicating with the first bypass passage through the adjustment hole.
The fluid pressure cylinder according to any one of claims 1 to 3, wherein the bypass passage is closed when the switching member abuts on an opening of the second bypass passage to the adjustment hole.

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