JP2015158258A - Double motion type fluid pressure cylinder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fluid pressure cylinder capable of driving a high load without being influenced by pressure state in one chamber of a cylinder main body by supplying a high pressure working fluid to the other chamber at the time of both elongation and retraction thereof.SOLUTION: A cylinder main body 20 has at an upper end part thereof a partition wall 22 fixed, a movable cylinder 23 is inserted and fitted into the cylinder main body 20, the movable cylinder 23 is arranged to pass through the partition wall 22, a first oil chamber 24 is provided between a lower end part of the movable cylinder 23 and the cylinder main body 20, a second oil chamber 25 is provided between a lower part of the movable cylinder 23 and the fixed partition wall 22, a third oil chamber 26 is provided between the fixed partition wall 22 and an upper part of the movable cylinder 23, and a changing-over of a directional control valve 40 provides a selective connection of both the first oil chamber 24 and the third oil chamber 26, the second oil chamber 25 to a high-pressure side from a hydraulic pump 43, and a low-pressure side of a working oil tank 44, respectively.

Description

  The present invention relates to a double-acting hydraulic cylinder in which a driving force based on fluid pressure acts on both an expansion side and a reduction side.

  As a fluid pressure cylinder, for example, a hydraulic cylinder has a piston that divides a cylinder body into two chambers, a piston rod is connected to the piston, and the piston rod protrudes from one end of the cylinder body. In other words, the driving force is generated by extending or contracting the piston rod connected to the piston with respect to the cylinder body. As a hydraulic cylinder, a single-acting type and a double-acting type are known. The single-acting hydraulic cylinder has a hydraulic drive force acting on either side of the push-pull, and the return side (reduction side) is of the type that depends on its own weight or load, or depends on the spring force. . On the other hand, the double-acting type hydraulic cylinder drives both pushing and pulling (extension side and reduction side) by the action of hydraulic pressure.

  A schematic configuration of a general double-acting hydraulic cylinder is shown in FIG. In the figure, 1 is a cylinder body, 2 is a piston, and 3 is a piston rod. A piston rod 3 is connected to the piston 2, and the piston rod 3 is led out from the rod end side of the cylinder body 1. The piston 2 is divided into two chambers, a bottom chamber 1a and a rod chamber 1b. The piston 2 slides inside the cylinder body 1 according to supply and discharge of pressure oil, and the load W is connected to the end of the piston rod 3 connected to the piston 2.

  The cylinder body 1 is provided with a port a communicating with the bottom chamber 1a and a port b communicating with the rod chamber 1b. Pipes 4a and 4b connected to the direction switching valves are connected to the ports a and b, respectively. As a result, the bottom chamber 1a and the rod chamber 1b are switched and connected to a hydraulic pump or a hydraulic oil tank.

  When the direction of the direction switching valve is switched, when the bottom chamber 1a side of the cylinder body 1 becomes a high pressure (pump pressure) and the rod chamber 1b side becomes a low pressure (tank pressure), the piston rod 3 expands due to the differential pressure, and the piston rod 3 The load W connected to the tip is lifted. Further, when the rod chamber 1b side is set to a high pressure and the bottom chamber 1a side is set to a low pressure, the piston rod 3 is reduced, and the load W is reduced. Further, the direction switching valve is provided with a shut-off position. In this shut-off position, neither the bottom chamber 1a nor the rod chamber 1b is connected to either the hydraulic pump or the hydraulic oil tank, and the piston 2 and the piston rod 3 are locked. It becomes a state.

  In this way, since the hydraulic driving force acts when the piston rod is extended and contracted, the hydraulic cylinder can be operated regardless of the direction in which the load W is applied. In this stroke, it is possible to stop at an arbitrary position and hold at the stop position.

  Here, an example of a double-acting hydraulic cylinder is shown in Patent Document 1. In Patent Document 1, a cylinder body defined by a piston is partitioned into a bottom chamber and a rod chamber by a piston, but the bottom chamber is always connected to a hydraulic oil tank. The piston is connected to a hollow piston rod with a lid, and this piston rod extends from the rod chamber side to the outside of the cylinder body. Thus, in the rod chamber, an annular chamber is formed between the inner wall of the cylinder body and the piston rod, and the inside of the hollow piston rod is a cylindrical chamber. A first pressure receiving surface on the outer peripheral side of the piston faces the annular chamber, and an inner surface of the upper end portion of the cylindrical chamber is a second pressure receiving surface.

  The first and second pressure receiving surfaces are provided with ports, and each port is selectively connected to a hydraulic pump or a hydraulic oil tank. When a high pressure is applied to the first pressure receiving surface in the annular chamber and the second pressure receiving surface is at the tank pressure, the piston rod is displaced in the reduction direction, the first pressure receiving surface is at a low pressure, The pressure receiving surface becomes high pressure, and the piston rod extends. Here, since the bottom chamber in the cylinder body is always connected to the hydraulic oil tank, when the piston is displaced, the bottom chamber expands and contracts, and thus the volume change of the bottom chamber is absorbed.

JP 2000-346012 A

Generally, in a double-acting hydraulic cylinder, when it is stably stopped at a predetermined position, the bottom chamber and the rod chamber are kept in a pressure balanced state, that is, maintained at the same pressure state. Will be. The hydraulic cylinder is driven by a differential pressure between the bottom chamber and the rod chamber. Accordingly, in order to operate the hydraulic cylinder in a direction opposite to gravity in a state where a load is applied, approximately twice as much driving force is required. For this reason, the cylinder and the piston rod need to have durability against this driving force, and their rigidity must be increased, resulting in an increase in weight.
In Patent Document 1, a hydraulic cylinder structure is prevented from buckling by supporting a load on the hydraulic cylinder by filling a cylinder body formed of a cylindrical chamber with a working fluid. However, in this structure, the pressure receiving area in the piston rod is small, and the working fluid is at a higher pressure than the conventional hydraulic cylinder, and the strength of the structure becomes a problem. On the other hand, in order to reduce the pressure of the working fluid, it is necessary to increase the pressure receiving area, and there is a problem that the diameter of the hydraulic cylinder increases.

  By the way, in the hydraulic cylinder of Patent Document 1, since the bottom chamber is connected to the hydraulic oil tank, the first pressure receiving surface and the second pressure receiving pressure can be stopped at a position in the middle of the stroke of the hydraulic cylinder. The pressure balance with the surface must be accurate. Therefore, in a state where a load is applied to the piston rod, the hydraulic cylinder is stabilized at the most contracted position and cannot be stably held at a position in the middle of the stroke. That is, there is a problem similar to that of a single-acting hydraulic cylinder.

  The present invention has been made in view of the above points. The object of the present invention is to supply a high-pressure working fluid to the one side chamber of the cylinder body both at the time of expansion and at the time of contraction. It is an object of the present invention to provide a fluid pressure cylinder capable of driving a large load without being affected by the pressure state.

  In order to achieve the above-mentioned object, the present invention includes a cylinder body, a fixed partition fixed to the cylinder body, and at least one working fluid chamber formed on both sides of the fixed partition. In order to define each working fluid chamber, at least one movable partition wall slidable on the cylinder body and working fluid chambers located on both sides of the fixed partition wall are divided into a high pressure side and a low pressure side. And a control valve that is switched and connected.

  Here, the fixed partition is fixedly held with respect to the cylinder body, and at least two working fluid chambers are provided inside the cylinder body. These working fluid chambers are disposed at least on both sides of the fixed partition wall. The surface opposite to the side facing the fixed partition wall is a movable partition wall, and the movable partition wall is slidably displaced with respect to the cylinder body by supplying and discharging the working fluid. Accordingly, working fluid chambers for supplying and discharging working fluid are formed on both sides of the fixed partition wall.

  The cylinder body can be configured to have a rod on its central axis. The rod guides the movable partition. The rod can be connected to the fixed partition, or provided so as to penetrate the fixed partition, and the movable partition can be connected to both ends thereof.

  Among the working fluid chambers provided in the cylinder body, the movable partition wall facing the working fluid chamber on either side moves along the cylinder body when high-pressure working fluid is supplied into the working fluid chamber. A load is connected to the movable partition, and the load is driven up and down together with the movable partition. At this time, the working fluid chamber on the other movable partition side is at a lower pressure than the working fluid chamber on the high pressure side. As a result, the load can be driven by the pressure of the working fluid chamber on the high-pressure side, a predetermined pressure can be applied to the other working fluid chamber on the low-pressure side, and no pressure is applied (fluid pressure is generated. Or a negative pressure state.

  If the low-pressure side working fluid chamber is in a non-pressure state, the load can be driven only by the high-pressure side pressure, and the low-pressure side working fluid chamber does not become a resistance when the hydraulic cylinder operates. That is, the same function as that of a single-acting cylinder is exhibited, and the load can be driven with a pressure lower than that of a conventional double-acting cylinder. Even if the fluid cylinder extends or contracts, it substantially functions as a single-acting cylinder. Here, the load may act not only on the cylinder body in the compression direction but also on the tension direction.

  The fixed partition is fixed to the cylinder body, the movable partition slides along the inner surface of the cylinder body, and at least one of the movable partitions is a movable cylinder formed in a telescope shape that can slide relative to the cylinder body. The cylinder body and the movable cylinder overlap each other, and the length of the entire cylinder is shortened accordingly. The rod guides the movable partition in the cylinder operating direction, and can also be configured to exhibit the function of connecting the two movable partitions.

  When configured as a hydraulic cylinder that uses hydraulic fluid as the working fluid, the control valve switches the direction in which the hydraulic pump and the hydraulic oil tank are selectively connected to the hydraulic fluid chamber on one side and the hydraulic fluid chamber on the other side. A valve. The direction switching valve is provided with two switching positions in which one of the two working fluid chambers is connected to the hydraulic pump and the other is connected to the hydraulic oil tank. It is desirable to provide a neutral position that does not connect to the tank. The oil passage for supplying and discharging the working fluid to and from the working fluid chamber formed on both sides of the fixed partition can be provided in the length direction of the rod, and the oil passage is provided in the fixed partition. You can also.

  In order to minimize the pressure of the cylinder body when the hydraulic cylinder is stationary, electromagnetic relief valves are connected to both chambers with the movable partition interposed therebetween. The electromagnetic relief valve exhibits a relief function, and can adjust the relief pressure in the oil chambers on both sides of the movable partition wall in proportion to the current applied to the pilot portion from the outside. Therefore, when the hydraulic cylinder is stationary, the relief pressure is set according to the load acting on the hydraulic cylinder and based on the pressure receiving area difference on both sides of the movable partition wall, so that the hydraulic cylinder is held stationary with the minimum pressure. Will be able to. Further, when the hydraulic cylinder is driven, the set pressure of the electromagnetic relief valve connected to the working fluid chamber on the high pressure side is increased to apply the driving pressure to the movable partition wall.

  When driving the load connected to the fluid pressure cylinder, it can be driven by the high-pressure working fluid supplied to the working fluid chamber on one side in either the extending direction or the contracting direction. Therefore, the cylinder body and the rod can be prevented from being deformed or damaged, and the fluid pressure cylinder can be driven smoothly.

1 is a configuration explanatory diagram of a double-acting hydraulic cylinder and a hydraulic circuit showing a first embodiment of the present invention. FIG. It is composition explanatory drawing which shows the modification of the hydraulic circuit in the 1st Embodiment of this invention. FIG. 4 is a configuration explanatory diagram of a double-acting hydraulic cylinder showing a second embodiment of the present invention. In the 2nd Embodiment of this invention, it is a structure explanatory drawing which shows the hydraulic circuit which provided the electromagnetic relief valve. It is composition explanatory drawing of the double acting type hydraulic cylinder which shows the 3rd Embodiment of this invention. It is a structure explanatory view of the double action type hydraulic cylinder showing the 4th embodiment of the present invention. It is a structure explanatory view of a double acting type hydraulic cylinder showing a 5th embodiment of the present invention. It is composition explanatory drawing of the double acting type hydraulic cylinder which shows the 6th Embodiment of this invention. It is composition explanatory drawing of the double acting type hydraulic cylinder which shows the 7th Embodiment of this invention. It is a structure explanatory view of a double acting hydraulic cylinder showing an eighth embodiment of the present invention. It is composition explanatory drawing of the double acting type hydraulic cylinder which shows the 9th Embodiment of this invention. FIG. 2 is a configuration explanatory diagram of a general double-acting hydraulic cylinder.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. First, FIG. 1 shows a schematic configuration of a double-acting hydraulic cylinder as a first embodiment of a double-acting hydraulic cylinder. In the following description, a hydraulic cylinder using hydraulic oil is used as the working fluid. However, it can be configured as a fluid pressure cylinder using other working fluid such as air. In the following description, the vertical direction refers to the vertical direction of the drawings.

  In the figure, 10 is a double-acting hydraulic cylinder, 11 is a hydraulic circuit for supplying and discharging pressure oil to and from this hydraulic cylinder 10, and 12 is a load acting on the hydraulic cylinder 10.

  The hydraulic cylinder 10 has a cylinder main body 20 made of a cylindrical member with a bottom and no lid. The cylinder main body 20 is connected to a fixed portion such as a predetermined structural member. The load 12 is movable with respect to the fixed portion, and is operated by a hydraulic driving force to drive the load 12 itself or a movable member connected to the load 12.

  A rod 21 is fixedly provided on the bottom surface 20 a of the cylinder body 20. The rod 21 extends upward so as to penetrate the cylindrical body portion 20 b, and a fixed partition 22 is connected to the tip of the rod 21. A movable cylinder 23 is telescopically inserted from the upper end opening 20c side of the cylinder body 20, and the movable cylinder 23 is reciprocally slid along the inner surface of the cylinder body 20 in the direction of the arrow in the figure. Become.

  Three oil chambers 24 to 26 are defined in the hydraulic cylinder 10 by the cylinder body 20 and the movable cylinder 23 connected in a telescopic manner. A first oil chamber 24 is defined between the bottom surface 20a of the cylinder body 20 and the lower end surface of the movable cylinder 23, and a second oil chamber 25 is defined between the movable cylinder 23 and the fixed partition wall 22. A third oil chamber 26 is defined between the first oil chamber 26 and the second oil chamber 26. The lower end surface of the movable cylinder 23 becomes the first pressure receiving surface 27 that receives the pressure of the first oil chamber 24, and the upper inner surface of the movable cylinder 23 becomes the second pressure receiving surface 28. Further, the lower inner surface of the movable cylinder 23 is a third pressure receiving surface 29. Here, seal members 30 are interposed between the first oil chamber 24 and the second oil chamber 25 and between the second oil chamber 25 and the third oil chamber 26, respectively. .

  In the hydraulic cylinder 10 having the above configuration, a load 12 acts on the upper end surface of the movable cylinder 23, and the load 12 is driven by the operation of the hydraulic cylinder 10. The rod 21 is provided with a first oil passage 31 and a second oil passage 32, the first oil passage 31 is connected to the third oil chamber 26, and the second oil passage 32 is It is connected to the second oil chamber 25. Further, the cylinder body 20 is formed with a port 33 of the first oil chamber 24.

  The hydraulic circuit 11 connected to the hydraulic cylinder 10 has a direction switching valve 40 as a control valve. The second oil passage 32 leading to the port 33 of the first oil chamber 24 and the third oil chamber 26 becomes a joined pipe 41, and the first oil passage 31 leading to the second oil chamber 25 is connected to the pipe 42. Is connected. The other ends of these pipes 41 and 42 are connected to the direction switching valve 40. A hydraulic pump 43 and a hydraulic oil tank 44 are connected to the direction switching valve 40, and a pipe 41 and a pipe 42 are selectively connected to the hydraulic pump 43 and the hydraulic oil tank 44 via the direction switching valve 40. It will be. That is, the direction switching valve 40 connects the pipes 41, 42 to the hydraulic pump 43 and the hydraulic oil tank 44, the neutral position (A), the pipe 41 to the hydraulic pump 43, and the pipe 42 to the hydraulic oil. It is possible to switch between the first switching position (b) connected to the tank 44 and the second switching position (c) where the pipe 41 is connected to the hydraulic oil tank 44 and the pipe 42 is connected to the hydraulic pump 43. ing.

  The hydraulic cylinder 10 configured as described above drives the load 12 by supplying and discharging pressure oil. When the directional control valve 40 constituting the hydraulic circuit 11 is operated to switch from the neutral position (A) to the first switching position (B), the pipe 41 is connected to the hydraulic pump 43 to become a high pressure state, that is, a pump pressure. The pipe 42 is connected to the hydraulic oil tank 44 to be in a low pressure state, that is, a tank pressure. As a result, pump pressure is supplied to the first oil chamber 24 and the third oil chamber 26, and the second oil chamber 25 becomes tank pressure. While the pump pressure acts on the first pressure receiving surface 27 and the third pressure receiving surface 29, the second pressure receiving surface 28 is in a tank pressure state, so that the movable cylinder 23 of the hydraulic cylinder 10 extends with respect to the cylinder body 20. Thus, a driving force is applied in the direction of lifting the load 12.

  On the other hand, when the direction switching valve 40 is switched to the second switching position (c), pump pressure acts on the pipe 42 and the pipe 41 becomes tank pressure. As a result, the pump pressure is guided to the second oil chamber 25, and the first and third oil chambers 24 and 26 become the tank pressure. As a result, the first pressure receiving surface 27 and the third pressure receiving surface 29 become tank pressure, and the pump pressure acts on the second pressure receiving surface 28, so that the movable cylinder 23 of the hydraulic cylinder 10 moves against the cylinder body 20. The driving force acts in the direction in which the load 12 is pulled down.

  Here, the load 12 acts on the movable cylinder 23. The movable cylinder 23 is slidably displaced in the direction of the arrow in FIG. Will expand and contract.

  When the hydraulic cylinder 10 is extended, pressure is supplied into the third oil chamber 26, and pump pressure acts on the second pressure receiving surface 28. The surface facing the second pressure receiving surface 28 is fixed to the fixed partition wall 22. Therefore, it is driven by the pressure supplied to the third oil chamber 26 without being affected by the pressures of the other oil chambers 24, 26. Since the pump pressure is introduced into the first oil chamber 24 when the hydraulic cylinder 10 is extended, the same pressure as the third pressure receiving surface 29 acts on the first pressure receiving surface 27. Therefore, the pressure acting on the first pressure receiving surface 27 functions as a driving force in the extending direction of the hydraulic cylinder 10. On the other hand, when the hydraulic cylinder 10 is contracted, pressure is supplied into the second oil chamber 25, and pump pressure acts on the third pressure receiving surface 29, and the surface facing the third pressure receiving surface 29. Is also a fixed partition wall 22. Therefore, it is driven by the pressure of the second oil chamber 25 at the time of reduction. As a result, the load 12 moves up and down by the stroke S.

  Here, the first oil chamber 24 becomes a pump pressure at the time of expansion and a tank pressure at the time of contraction. This is due to the movement of the movable cylinder 23, resulting in a change in volume of the second and third oil chambers 25 and 26. Correspondingly, the driving pressure is the pressure of the third oil chamber 26 and the second oil chamber 25 at the time of extension. That is, even when the hydraulic cylinder 10 is extended or contracted, the hydraulic cylinder 10 is driven only by the pressure supplied to the oil chamber on either side across the fixed partition wall 22 and is affected by the pressure in the other oil chambers. Not receive.

  By the way, since the same pressure as that of the third oil chamber 26 is introduced into the first oil chamber 24 at the time of extension, it may be at the time of extension or at the time of reduction despite being a double-acting hydraulic cylinder. However, it operates in the same manner as a single-acting hydraulic cylinder. Therefore, the load 12 can be driven with a pressure lower than that of a general double-acting hydraulic cylinder.

  As a result, the supply pressure to the hydraulic cylinder by the hydraulic pump can be suppressed, and the load on the hydraulic pump can be reduced. Further, since it is not necessary to introduce an excessive pressure to the hydraulic cylinder, the hydraulic cylinder 10 can be smoothly operated even when a heavy load is applied, and the cylinder body 20 and the movable cylinder constituting the hydraulic cylinder 10 can be operated. It is possible to prevent the rod 23 and the rod 21 from being deformed or damaged by hydraulic pressure or the like, and further to prevent the seal member 30 from leaking. Thereby, the hydraulic cylinder 10 can be reduced in size and weight, and the operating efficiency is improved.

  FIG. 2 shows a modification of the hydraulic circuit connected to the hydraulic cylinder 10 of FIG. In the hydraulic circuit of FIG. 1, the port 33 of the first oil chamber 24 and the second oil passage 32 that communicates with the third oil chamber 26 merge with the pipe 41, and the first oil that communicates with the second oil chamber 25. A pipe 42 is connected to the passage 31. However, in the configuration of the hydraulic circuit in FIG. 2, the pipe 41 a is connected to the port 33, and the second oil passage 32 is connected to a pipe 41 b different from the pipe 41 a. The pipe 41 a and the pipe 41 b merge at the direction switching valve 40. Further, the first oil passage 31 is connected to the pipe 42 and is connected to the direction switching valve 40. This is the same as the configuration of FIG. Further, proportional electromagnetic relief valves 50, 51 and 52 are connected to the pipes 41a, 41b and 42, respectively, and these proportional electromagnetic reliefs 50, 51 and 52 have independent relief set pressures.

  By configuring as shown in FIG. 2, the relief pressures of the three oil chambers 24 to 26 can be set independently, and can be arbitrarily set based on an external control signal. Therefore, the pressure in each of the oil chambers 24 to 26 can be minimized, particularly when the hydraulic cylinder 10 is stationary. As a result, damage to each part such as buckling of the piston rod 21 and damage to the cylinder body 20 is not received.

  In the first embodiment described above, the rod 21 is provided with the oil passages 31 and 32, but the second embodiment shown in FIG. 3 and the hydraulic pressure shown in FIG. In the circuit configuration, a fixed partition wall 122 is fixedly provided at an intermediate position of the cylinder body 120. A movable cylinder 123 is inserted in a telescope shape above the fixed partition wall 122. A movable partition 150 is provided below the fixed partition 122, and the movable partition 150 slides along the inner surface of the cylinder body 120. The rod 121 extends so as to penetrate the fixed partition wall 122, the portion of the third pressure receiving surface 129 of the movable cylinder 123 is fixed to the upper end of the rod 121, and the movable partition wall is connected to the lower end portion. 150 are connected.

  First, second, and third oil chambers 124, 125, 126 are formed in the cylinder body 120 from the upper side, and the first oil chamber 125 and the third oil chamber 126 communicate with the first oil chamber 125. The second oil passages 131 and 132 are formed in the fixed partition wall 122.

  In the case of the second embodiment, when the hydraulic circuit is provided with a relief function, proportional electromagnetic relief valves 150 and 151 are connected to the pipes 141 and 142, respectively. However, the port 133 of the oil chamber 124 is not merged with the first oil chamber 124 and is always kept at the tank pressure.

  In FIG. 3, the movable cylinder 123 is inserted into the cylinder body 120. However, the movable cylinder 123 may be inserted into the cylinder body 120 like the movable cylinder 123 ′ shown in FIG. 3 and 5, the movable cylinders 123, 123 ′ and the movable partition wall 150 are connected to both ends of the rod 121 that penetrates the fixed partition wall 122. There is no possibility that the cylinders 123 and 123 ′ deviate from the cylinder body 120.

  Next, in the fourth and fifth embodiments shown in FIGS. 6 and 7, the cylinder body 120 ′ is formed in a cylindrical shape with both ends opened, and the lower surface of the movable partition wall 150 is exposed to the outside. doing. Therefore, in these embodiments, the second and third oil chambers 125 and 126 are formed, but the first oil chamber is not formed. Components other than those described above are denoted by the same reference numerals as those in FIGS. 3 and 4, and descriptions of specific configurations thereof are omitted.

  By the way, in each of the above-described embodiments, the movable cylinder is directed upward, and the load is applied in the direction in which the movable cylinder positioned on the upper side is compressed. However, the embodiment of FIG. In FIG. 2, the configuration in which the direction in which the load 212 acts is the pulling direction of the movable cylinder 223 is shown. The cylinder body 220 has a lid, and a fixed partition 222 is formed at an intermediate position. In addition, a movable partition wall 250 is provided at an upper position of the fixed partition wall 222, whereby the first oil chamber 224 is movable between the end wall portion and the movable partition wall 250 inside the cylinder body 220. A second oil chamber 225 is formed between the partition wall 250 and the fixed partition wall 222, and a third oil chamber 226 is formed between the fixed partition wall 222 and the movable cylinder 223. The rod 221 is connected between the movable partition wall 251 and the movable cylinder 223, and has a first oil passage 231 that communicates with the first oil chamber 224 and a second oil passage that communicates with the second oil chamber 225. 232 is provided.

  By configuring as described above, the load 212 acts in the direction of pulling the movable cylinder 223 and the rod 221 downward. As a result, even when a large pressure is applied, the movable cylinder 223 and the rod 221 are deformed. Can be prevented. In the sixth embodiment shown in FIG. 8, the movable cylinder 223 is fitted to the cylinder body 220. However, as in the seventh embodiment shown in FIG. 9, the movable cylinder 223 ′ is replaced with the cylinder body. You may comprise so that it may insert in 220.

  10 and 11 show an embodiment of the eighth and ninth embodiments in a hydraulic cylinder having a load 312 acting in the direction of pulling downward. In these embodiments, as in the embodiments of FIGS. 4 and 5, the cylinder body 320 has a cylindrical shape with both ends open, and the upper surface of the movable partition wall 350 is exposed to the outside. 4 and 5, the movable cylinder 323 is fitted into the cylinder main body 320, and FIG. 9 is the movable cylinder 323 'inserted into the cylinder main body 320. Is shown. A second oil passage connected to a third oil chamber 326 located on the upper side of the movable partition wall 350 is connected to the rod 321 penetrating the fixed partition wall 322 and having both ends connected to the movable partition wall 350 and the movable cylinder 323. 332 is formed, and a port 333 communicating with the second oil chamber 325 is formed in the movable cylinders 323 and 323 ′. With this configuration, even when a large pressure is applied to the movable cylinders 323, 323 ′ and the rod 321 when the load 312 is driven, the movable cylinders 323, 323 ′ and the rod 321 are deformed. Can be prevented.

  Here, in the hydraulic cylinder shown in FIG. 4 and subsequent figures, the hydraulic circuit including the direction switching valve connected to the hydraulic cylinder can have the same configuration as that shown in FIG. 1, and the same as that shown in FIG. A proportional electromagnetic relief may be provided.

DESCRIPTION OF SYMBOLS 10 Hydraulic cylinder 11 Hydraulic circuit 12,212,312 Load 20,120,220,3120 Cylinder main body 21,121,221,321 Rod 22,122,222,322 Moving partition 23,123,123 ', 223,223', 323, 323 'movable cylinders 24, 124, 224 first oil chambers 25, 125, 225, 325 second oil chambers 26, 126, 226, 326 third oil chamber 40 direction switching valves 50.51, 52 proportional Solenoid relief valve

Claims (5)

A cylinder body,
A fixed partition wall fixed to the cylinder body;
Formed on both sides of the fixed partition wall, each of at least one working fluid chamber;
At least one movable partition wall slidable on the cylinder body to partition each working fluid chamber;
A double-acting fluid pressure cylinder having a control valve for switching and connecting a working fluid chamber located on both sides of the fixed partition wall to a high pressure side and a low pressure side.   2. The compound according to claim 1, wherein a rod is provided on a central axis of the cylinder body, and the movable partition is guided by the rod and is slidably displaced inside the cylinder body. Dynamic fluid pressure cylinder.   The double-acting fluid pressure cylinder according to claim 2, wherein the pipe connected to the control valve is connected to each working fluid chamber via an oil passage formed in the rod or the fixed partition wall. .   The movable cylinder is connected to the cylinder body in a telescope shape, and at least the one working fluid chamber is formed between the fixed partition wall and the movable cylinder. The double-acting fluid pressure cylinder according to claim 2.   5. The electromagnetic relief valve capable of adjusting a set pressure is connected to the working fluid chambers located on both sides of the fixed partition wall, respectively. 5. A double-acting fluid pressure cylinder as described in the paragraph.