JP4651437B2 - Hydraulic cylinder - Google Patents

Description

  The present invention relates to a hydraulic cylinder having an accumulator disposed in a piston rod.

  Conventionally, for example, hydraulic cylinders are used to drive working machines such as buckets in various civil engineering machines such as hydraulic excavators. The hydraulic cylinder includes a piston rod that reciprocates in the cylinder, and a piston that is fitted into the cylinder is fixed to one end of the piston rod. The cylinder is divided into two cylinder chambers by the piston.

  By supplying pressure oil to the cylinder chamber or discharging pressure oil from the cylinder chamber, the piston rod can be expanded and contracted. By a telescopic operation with respect to the piston rod, it is possible to drive and operate a working machine such as a bucket connected to the tip of the piston rod or the bottom side of the cylinder.

  In order to control the movement of the work implement, the supply of pressure oil to the cylinder chamber or the discharge of pressure oil from the cylinder chamber may be stopped, and the linear sliding of the piston rod may be temporarily stopped. In some cases, the piston is caused to collide with a cylinder bottom or the like to suddenly stop the sliding of the piston. In these cases, if the sliding of the piston is suddenly stopped, the pressure oil in the cylinder chamber is compressed by the inertial force of the piston. At this time, since the hydraulic oil is an incompressible fluid, a hydraulic pressure peak occurs in the cylinder chamber.

  The sliding of the piston suddenly stops due to the hydraulic pressure in the cylinder chamber that has reached the hydraulic pressure peak. However, a large impact is generated on the cylinder itself due to the occurrence of a hydraulic pressure peak. This impact is transmitted to a working machine or the like connected to a hydraulic cylinder or piston rod, and generates severe vibration and noise.

  In order to alleviate this, it is effective to use an accumulator, but a space is required to install the accumulator. Further, when the accumulator is disposed outside, there is a problem that the responsiveness as the accumulator is deteriorated due to the length of the pipe connecting the accumulator and the hydraulic cylinder. In order to solve these problems, there has been proposed an accumulator provided in a hydraulic cylinder.

  As an apparatus in which an accumulator is disposed in a hydraulic cylinder, a cylinder device (see Patent Document 1) has been proposed. Further, as an accumulator provided in a piston rod, an accumulator cylinder (see Patent Document 2) has been proposed.

  FIG. 11 shows a cross-sectional view of the cylinder device described in Patent Document 1 as Conventional Example 1 in the present invention. As shown in FIG. 11, a piston 52 is slidably fitted in a cylinder body 51 of the cylinder device 50. A piston rod 53 is integrally provided on one surface of the piston 52.

  The piston rod 53 protrudes outward from one end of the cylinder body 51, and an idler (not shown) is connected to the tip of the piston rod. External force applied to the idler or the like can be received by the piston rod 53.

  The cylinder body 51 is defined by a piston 52 into a first oil chamber 54a and a second oil chamber 54b. The first oil chamber 54a is connected to a hydraulic circuit by a port 55 formed in the cylinder body. The second oil chamber 54b is connected to the hydraulic circuit by a port 58 formed in the cylinder body. Pressure oil of an incompressible fluid can be supplied to the first oil chamber 54a and the second oil chamber 54b.

  An air chamber 56 filled with a compressible gas is formed on the left side of the second oil chamber 54b. A diaphragm 57 is defined between the second oil chamber 54 b and the air chamber 56. The diaphragm 57 and the air chamber 56 constitute an accumulator function. By controlling the switching valve of the hydraulic circuit connected to the ports 55 and 58, it is possible to control the supply and discharge of pressure oil to and from the first oil chamber 54a and the second oil chamber 54b. Forward and backward movement and positioning stop can be performed.

  It is assumed that the hydraulic pressure in the first oil chamber 54a is lower than the pressure in the air chamber 56 when the rod 53 is in the holding position. At this time, the diaphragm 57 is deformed to the second oil chamber 54b side by the pressure in the air chamber 56, and the piston 52 is moved in a direction to reduce the first oil chamber 54a via the pressure oil in the oil chamber 54b. be able to. Thereby, the pressure drop in the first oil chamber 54a can be compensated.

  Further, when an external force is applied to the rod 53, the diaphragm 57 is expanded in the air chamber 56 via the pressure oil in the second oil chamber 54b, and the piston 52 is compressed while compressing the inert gas in the air chamber 56. Can be retreated. Thereby, the external force applied to the rod 53 can be absorbed.

  FIG. 12 shows a cross-sectional view of an accumulator cylinder described in Patent Document 2 as Conventional Example 2 of the present invention. As shown in FIG. 12, a piston rod 73 is provided in the cylinder 60. A space 63 is formed at one end of the piston rod 73, and a piston 62 is formed at the tip thereof. The cylinder 62 is defined by the piston 62 into two cylinder chambers 74 and 75.

  The cylinder chamber 74 is connected to a hydraulic circuit (not shown) through a port 70, and the cylinder chamber 75 is connected to a hydraulic circuit (not shown) through a port 69. By supplying pressure oil to the cylinder chamber 74 or the cylinder chamber 75, the piston rod 73 can be driven to extend and contract.

  In the space 63, a spring 68 and an accumulator piston 67 pressed by the spring 68 are housed, and one end of the accumulator piston 67 is slidably fitted into a pressure oil hole 72 formed in the ground 66. . The ground 66 is supported and fixed by a piston rod 73 and a ground presser 65 fixed to the opening of the space 63. A pressure oil hole 72 formed in the gland 66 communicates with a through hole 64 formed in the gland retainer 65. The space 63 communicates with the cylinder chamber 74 through the pressure oil hole 71.

  Even when the pressure in the cylinder chamber 75 decreases when the piston rod 73 is in the holding position, the accumulator piston 67 can be moved toward the cylinder chamber 75 by the biasing force of the spring 68. Thereby, the pressure drop in the cylinder chamber 75 can be compensated.

When an external force is applied to the piston rod 73 in the direction in which the cylinder chamber 75 is compressed, the pressure in the cylinder chamber 75 increases when the piston 62 moves rapidly in the direction in which the cylinder chamber 75 is contracted. At this time, pressurized oil that has become high pressure from the through hole 64 of the gland retainer 65 acts on the accumulator piston 67 and compresses the spring 68 to absorb the pressure increase due to external force.
JP 2003-343516 A Japanese Patent Laid-Open No. 49-104075

  The volume as the accumulator and the gas pressure set in the accumulator need to be optimally set according to the use of the working machine driven by the hydraulic cylinder equipped with the accumulator. In particular, when the volume of the accumulator is not set to an optimal volume and is smaller than the optimal volume, the function as an accumulator will not work. Further, when the accumulator volume is larger than the optimum volume, the accumulator functions only in a slick manner, and the actual work cannot be performed by the working machine.

  In the cylinder device 50 described in Patent Document 1, since the volume of the air chamber 56 is fixed, the cylinder device 50 can be applied only to the cylinder device 50 for a working machine that has been determined in advance. Even when the cylinder device provided with the air chamber 56 is used for another working machine, the above-described problems occur. Further, in order to change the volume of the air chamber 56, individual processing corresponding to the volume of the air chamber is required. In addition, the processing for setting the volume of the air chamber to the optimum volume requires precise processing, which makes the processing work difficult and increases the cost.

  Also in the accumulator cylinder described in Patent Document 2, in order to make the accumulator volume optimal, the spring force of the spring 68 must be adjusted or the stroke of the accumulator piston 67 must be changed. However, adjusting the spring force of the spring 68 and changing the stroke of the accumulator piston 67 are extremely difficult operations.

  In order to change the volume of the accumulator, it is necessary to prepare a plurality of types of springs having different spring forces, and a plurality of accumulator pistons with different thicknesses of the head portions of the accumulator piston 67 are provided. I had to prepare. However, preparing a plurality of springs and accumulator pistons increases costs.

  An object of the present invention is to solve these problems and provide a hydraulic cylinder capable of changing the volume of an accumulator disposed in a piston rod with a simple configuration.

The object of the present invention can be achieved by the inventions described in claims 1 and 2 .
That is, in the present invention, as described in claim 1, in the hydraulic cylinder in which the accumulator is disposed in the piston rod, an adjusting member is disposed in the piston rod, and the gas of the accumulator is determined by the volume of the adjusting member. will by adjusting the chamber volume, wherein the adjusting member is constituted by a member of the volume fixed, Ri Na is disposed in the gas chamber or an oil chamber in the piston rod, wherein the adjustment member is in said piston rod The main feature is that the core is disposed in the gas chamber or the oil chamber .

Further, as described in claim 2 , the main feature is that the arrangement portion of the adjustment member and the configuration of the adjustment member are specified.

  In the present invention, the volume of the gas chamber of the accumulator disposed in the piston rod can be freely adjusted by the volume of the adjusting member disposed in the piston rod. Thereby, only by changing the volume of the adjusting member disposed in the piston rod, the gas chamber volume can be made optimum depending on the application of the hydraulic cylinder. In addition, a hydraulic cylinder with a high-performance accumulator can be provided.

  The adjusting member disposed in the piston rod can be disposed in either the gas chamber or the oil chamber in the piston rod. When the adjusting member is disposed in the gas chamber, the gas chamber volume can be adjusted between the accumulator piston and the adjusting member that define the inside of the piston rod into the gas chamber and the oil chamber. Further, when the adjustment member is disposed in the oil chamber, the gas chamber volume can be adjusted by changing the stroke amount of the accumulator piston.

As an adjustment member, it can comprise from a volume fixed member. In the case where the adjustment member is formed of a fixed-volume member, a member that can be disposed in the piston rod, such as a core , can be used. By changing the length, diameter, etc., as the core, the gas chamber volume can be changed easily and accurately to the optimum volume. Alternatively, by preparing a plurality of cores with a short length and arranging the cores with the short length in the piston rod according to the number corresponding to the hydraulic cylinder, the gas chamber volume can be easily made the optimum volume. Can be changed as follows. When a plurality of cores are used, it is desirable to connect and fix the cores to each other.

  When the core is slidably fitted in the piston rod, even if the piston rod vibrates due to the impact generated when the piston rod is stopped rapidly, the core and the piston rod A minute relative displacement can be generated through the minute gap. This minute relative displacement is consumed as frictional heat between the core and the piston rod, and vibration energy can be consumed as heat energy. Thereby, the vibration of the piston rod can be attenuated early, and the generation of vibration noise can be suppressed.

  Further, when an accumulator port connecting the accumulator and the cylinder chamber in the hydraulic cylinder is disposed in the vicinity of the piston of the hydraulic cylinder, bending stress acts on the piston rod with the piston root portion as a fulcrum. As a result, stress concentration occurs in the accumulation port. However, by arranging the core as the adjusting member in the present invention on the piston side, the bending rigidity in the vicinity of the accumulation port can be increased, and the risk of the piston rod being damaged can be greatly reduced. it can.

  Preferred embodiments of the present invention will be specifically described below with reference to the accompanying drawings. As the configuration of the hydraulic cylinder according to the present invention, in addition to the shape and arrangement described below, if the shape and arrangement can solve the problems of the present invention, those shapes and arrangement are adopted. It is something that can be done. For this reason, this invention is not limited to the Example demonstrated below, A various change is possible.

  FIG. 1 shows a cross-sectional view of a hydraulic cylinder according to an embodiment of the present invention. The hydraulic cylinder 1 includes a cylinder tube 2, a piston 3 and a piston rod 4. A cylinder head 6 is fixed to one end portion of the cylinder tube 2 with a bolt 30, and a cylinder bottom 7 is welded to the other end portion.

  Inside the cylinder tube 2, a reciprocating piston 3 is disposed, and the piston 3 is fixed to a piston rod 4 penetrating the cylinder head 6. Pressure oil can be supplied to the cylinder chamber 5a on the head side through the oil passage 9, and pressure oil is supplied to the cylinder chamber 5b on the bottom side through the oil passages 8a and 8b formed in the cylinder bottom 7. be able to.

  The piston rod 4 is hollow, the piston 3 is fixed to the outer peripheral side of one end, and a retaining member 11 is disposed on the inner peripheral side. A connecting member 15 is detachably fixed to the other end of the piston rod 4. An accumulator piston 13 is slidably disposed in the piston rod 4, and is defined by a gas chamber 31 and an oil chamber 32 by the accumulator piston 13. The oil chamber 32 communicates with the cylinder chamber 5a via an accumulation port 23 formed on the piston side of the piston rod 4.

  In the gas chamber 31, a core 14 as an adjusting member is disposed. The core 14 is fitted between the inner peripheral surface of the piston rod 4 through a minute gap. Although the core 14 can be press-fitted into the piston rod 4, the core 14 can be detachably disposed with respect to the piston rod 4 in order to adjust the length of the core 14 and the like. Is also desirable.

  The core 14 is sandwiched between the end of the piston rod 4 and the connecting member 15 via a flange portion 14 a formed at one end of the core 14. The flange portion 14a is sandwiched between the end portion of the piston rod 4 and the connecting member 15 so as to be able to move a minute distance in the piston axial direction. The core 14 has a through hole 14b formed in the axial direction thereof. The passage 15a formed in the connecting portion 15 and the gas chamber 31 can be communicated with each other through the through hole 14b. The gas filled in the gas chamber 31 can be supplied from the outside through the nipple 15b provided at the end of the passage 15a. The volume of the core 14 can be changed by changing the length or outer diameter of the core 14. It can also be changed by changing the diameter of the through hole 14b formed in the core 14.

  Next, the operation of the accumulator 12 will be described with reference to FIG. As shown in FIG. 1, it is assumed that the piston 3 is at the stroke end on the cylinder bottom 7 side. When pressure oil is supplied from the oil passage 8a, the end surface of the piston 3 is pressed by the supplied pressure oil as a pressure receiving surface. In order to secure a pressure receiving area on the end surface of the piston 3, a cross groove may be formed on the end surface of the piston 3.

  The piston 3 slides on the cylinder head 6 by the pressure oil supplied from the oil passage 8a, and the cylinder rod 4 can be extended. Thereby, the space | interval of the connection hole 34a formed in the connection part 15 and the connection hole 34b formed in the cylinder bottom 7 can be expanded. One of the pair of connection holes 34a and 34b is connected to a working machine (not shown) and the other connection hole is connected to a support member such as a boom. For this reason, a working machine etc. can be operated by widening or narrowing the space | interval of a pair of connection hole 34a, 34b.

  If the sliding of the piston 3 suddenly stops or the piston 3 collides with the cylinder head 6 during the sliding of the piston 3 by the pressure oil supplied from the oil passage 8a, the pressure in the cylinder chamber 5a becomes high. End up. That is, even if the supply of pressure oil supplied from the oil passage 8a is stopped to stop the sliding of the piston 3, the piston 3 reduces the cylinder chamber 5a by the inertial force of the piston 3 or the piston rod 4. Try to slide in the direction. For this reason, the pressure in the cylinder chamber 5a suddenly rises to a high pressure.

  When the pressure in the cylinder chamber 5 a increases and the increased pressure becomes higher than the pressure in the gas chamber 31, the pressure oil whose pressure has increased is introduced into the oil chamber 32 of the accumulator 12 from the accumulator port 23. The accumulator piston 13 is slid in the direction in which the gas chamber 31 is reduced by the pressure oil introduced into the oil chamber 32. Thereby, the pressure rise in the cylinder chamber 5a can be absorbed by raising the pressure of the gas chamber 31 in the accumulator 12.

  The amount of pressure increase in the cylinder chamber 5 a that can be absorbed by the gas chamber 31 of the accumulator 12 is set by the volume of the gas chamber 31 and the gas pressure charged in the gas chamber 31. In the present invention, since the volume of the gas chamber 31 can be adjusted by the volume of the core 14 disposed in the gas chamber 31 of the accumulator 12, the optimum state for the hydraulic cylinder 1 together with the gas pressure charged in the gas chamber 31 is achieved. Can be kept.

  When the piston 3 is slid to the cylinder bottom 7 side from the state in which the piston 3 is stopped, the piston 3 is slid by the pressure oil discharged from the accumulator port 23 of the accumulator 12 together with the pressure oil from the oil passage 9. it can. At this time, due to the gas pressure in the gas chamber 31, the accumulator piston 13 slides in a direction to reduce the volume of the oil chamber 32 until the volume of the gas chamber 31 returns to a preset volume.

  In FIG. 1, the plunger 10 that provides a cushioning action against the sliding of the piston 3 is not provided. However, as shown in FIG. 2, the plunger 10 may be disposed on the cylinder bottom 7 side of the piston 3 so as to extend from the center of the piston 3 in the piston axial direction.

  The plunger 10 can be engaged with the oil passage 8b opened in the cylinder bottom 7 so as to be freely inserted and removed. When pressure oil is supplied from the oil passage 9 and the piston 3 slides toward the cylinder bottom 7, the plunger 10 is inserted into the oil passage 8 b at the stroke end of the piston 3. As a result, the flow rate of the pressure oil flowing out from the cylinder chamber 5b through the oil passage 8b can be reduced, and a cushioning action can be given to the sliding of the piston 3.

  Further, in the hydraulic cylinder 1 shown in FIG. 1, when the piston 3 slides toward the cylinder head 6, the accumulator 12 absorbs the pressure increase in the cylinder chamber 5 a due to the sliding stop of the piston 3. Show. As the structure of the accumulator, the structure of an accumulator 12 'as shown in FIG. 3 may be used.

  In the accumulator 12 'shown in FIG. 3, instead of disposing the plunger 10 on the piston end surface, an accumulator port 23 is formed on the piston end surface. Since the accumulation port 23 is formed on the piston end face, no accumulation port is formed on the piston rod 4 as shown in FIG. The accumulator port 23 is configured to communicate with the oil chamber 32 through an oil passage 11 a formed in the retaining member 11.

  In FIG. 3, the plunger 10 is not disposed, but the plunger 10 may be disposed as shown in FIG. In that case, the accumulation port 23 can be formed so as to communicate with the cross groove formed in the piston end surface on the outer peripheral side of the plunger 10. The number of accumulation ports 23 can be at least one. Then, the oil passage 11 a can be formed in the retaining member 11 so that the accumulation port 23 and the oil chamber 32 communicate with each other.

  In the above description, when the piston 3 starts to slide from the stroke end on the cylinder bottom 7 side to the cylinder head 6 side, a cross groove is formed on the end surface of the piston 3 so that the piston 3 slides smoothly. I explained that I can do it. Instead of forming a cross groove on the end surface of the piston 3, an oil groove communicating with the oil passage 8b may be formed on the surface of the cylinder bottom 7 facing the piston 3. In this case, the accumulator port 23 formed so as to communicate with the cross groove can be formed at a portion of the piston 3 facing the oil groove communicated with the oil passage 8b.

  The operation of the accumulator 12 'will be described with reference to FIG. The piston 3 slides toward the cylinder bottom 7 by the pressure oil supplied from the oil passage 9. When sliding stops rapidly during the sliding of the piston 3 or at the stroke end, the pressure in the cylinder chamber 5b rises and tends to be high.

  When the pressure in the cylinder chamber 5b becomes higher than the pressure in the gas chamber 31 of the accumulator 12 ', the pressure oil in the cylinder chamber 5b is passed through the accumulator port 23 and the oil passage 11a so as to reduce the volume of the gas chamber 31. The oil chamber 32 is introduced. Thereby, the pressure rise in the cylinder chamber 5b can be absorbed by the accumulator 12 '. Thus, the pressure increase in the cylinder chamber 5a or the cylinder chamber 5b can be absorbed by the accumulators 12 and 12 '.

  Due to the rapid sliding stop of the piston 3, the piston 3 is repelled from the high pressure cylinder chamber and slides in the opposite direction to the previous sliding. When the piston 3 tries to return in the opposite direction, the pressure in the cylinder chamber in the direction in which the piston 3 tries to return rises and tries to push the piston 3 back. The vibration of the piston 3 is repeated until the pressures in both cylinder chambers are balanced. Due to the vibration of the piston 3, the piston rod 4 also vibrates.

  The vibration of the piston rod 4 causes a minute relative displacement between the core 14 and the piston rod 4 through a minute gap between them. In particular, in the present invention, the core 14 that adjusts the volume of the gas chamber 31 holds the flange portion 14 a between the connecting member 15 and the end of the piston rod 4 with a slight gap.

  For this reason, minute relative displacement is likely to occur between the core 14 and the piston rod 4, and the vibration of the piston rod 4 can be consumed as frictional heat between the core 14 and the piston rod 4. Therefore, the vibration energy by the piston rod 4 is consumed as thermal energy, and the vibration of the piston rod 4 can be attenuated at an early stage. Generation of vibration noise can be suppressed by damping the vibration at an early stage.

  The configuration in which the core 14 is held between the connecting member 15 and the end of the piston rod 4 via a slight gap has been described. However, the core 14 is connected to the end of the connecting member 15 and the end of the piston rod 4. It is also possible to keep it immovable in the piston axis direction.

  4-5 is sectional drawing which shows other embodiment concerning this invention. 4 and 5, in order to facilitate the explanation of the configuration of each member, the arrangement relationship of each member is schematically illustrated in an exaggerated manner. For this reason, a part of the configuration is omitted. The second embodiment is characterized by the arrangement of the cores 18 and 17b in the piston rod 4. Other configurations can be the same as those in the first embodiment. For this reason, about the structure similar to Example 1, the description is abbreviate | omitted by using the same member code | symbol as the member code | symbol used in Example 1. FIG.

  In FIG. 4, the core 18 is supported by a support piece 15 c extending from the connecting member 15 in a state in which minute movement in the piston axial direction is allowed. As a result, the core 18 can be easily inserted into and removed from the piston rod 4. Further, since relative displacement can be generated between the core 18 and the piston rod 4, vibration generated in the piston rod 4 is quickly attenuated by frictional heat between the core 18 and the piston rod 4. Can be made.

  FIG. 5 shows an example in which the core 17 b is disposed on the oil chamber 32 side of the accumulator 12. The core 17b is fixed to the piston 17 of the hydraulic cylinder. In FIG. 6, the structure of the core 17b fixed to the piston 17 is shown as a perspective view. The core 17b is formed with an oil groove 17a that allows the accumulation port 23 and the oil chamber 32 to communicate with each other. Thereby, the cylinder chamber and the oil chamber 32 are communicated with each other by the accumulation port 23 and the oil groove 17a.

  The core 17 b can be formed integrally with the piston 17, or can be formed separately from the piston 17 and detachably attached to the piston 17. The volume of the gas chamber 31 can be easily adjusted by the volume of the core 17b.

  Further, as shown in FIG. 5, by arranging the core 17b on the accumulator port 23 side, the piston rod 4 and the cylinder tube (not shown in FIG. 5) are located when the piston rod 4 is extended. Even if a bending moment acts on the core 17b, it is possible to prevent the stress concentration at the accumulation port 23 from occurring due to the core 17b.

  7-10 is sectional drawing which shows another embodiment concerning this invention. 7 to 10, in order to easily explain the configuration of each member, the arrangement relationship of each member is schematically shown exaggeratedly. For this reason, a part of the configuration is omitted. The third embodiment is characterized in that an adjusting member having a variable volume is used as an adjusting member for adjusting the volume of the gas chamber 31. As other configurations, the same configurations as those in the first and second embodiments can be used. For this reason, about the structure similar to Example 1 and Example 2, the description is abbreviate | omitted by using the same member code | symbol as the member code | symbol used in Example 1 and Example 2. FIG.

  In FIG. 7, a balloon 20 having a variable volume is disposed in the gas chamber 31. A solid line state indicates a state where the balloon 20 is inflated, and a dotted line state indicates a state where the balloon 20 is deflated. By supplying the medium from the balloon filling port 21, the balloon 20 can be inflated to occupy a desired volume in the gas chamber 31. As the medium filled in the balloon 20, a compressible material such as gas can be used, but it is desirable to use an incompressible oil or the like that can arbitrarily adjust the volume of the balloon 20 according to the injection amount. .

  In the balloon 20, a pipe line 22 for filling the gas chamber 31 with gas is disposed. The gas can be filled into the gas chamber 31 from the accumulator gas filling port 22 a at one end of the pipe line 22. The duct 22 may be disposed in the gap between the balloon 20 and the piston rod 4 instead of being disposed in the balloon 20, or may be formed as a ventilation groove along the piston axial direction on the inner peripheral surface of the piston rod 4. It can also be left.

  In FIG. 8, a second oil chamber 25 having a variable volume is disposed in the gas chamber 31. The second oil chamber 25 is configured as an oil chamber defined by the second oil chamber piston 26. The periphery of the second oil chamber piston 26 is sealed by a piston seal 26a. In the second oil chamber 25, a telescopic tube 27 for supplying gas to the gas chamber 31 is disposed.

  Oil can be supplied into the second oil chamber 25 from the port 28, and the volume of the second oil chamber 25, that is, the volume of the gas chamber 31 can be adjusted by the amount of the supplied oil. The gas chamber 31 can be filled with a gas from the port 29 via the tube 27 that can be expanded and contracted. For this reason, even if the volume of the second oil chamber 25 is changed, the tube 27 expands and contracts as the volume of the second oil chamber 25 changes, so that the gas chamber 31 and the port 29 can always be in communication. it can. The port 29 can be provided with a nipple such as an automatic closing valve.

  Instead of using the tube 27 shown in FIG. 8, a gas filling pipe 33 is attached to the end of the flow path 29a in the piston rod 4 communicating with the accumulator gas filling port 29 as shown in FIG. You can also. The second oil chamber piston 26 can be slidably disposed by using the pipe line 33 as a guide path. Between the second oil chamber piston 26 and the inner peripheral surface of the piston rod 4 and between the second oil chamber piston 26 and the conduit 33 are sealed by piston seals 26a and 26b.

  8 and 9 show an example in which the second oil chamber 25 is disposed in the gas chamber 31, but the second oil chamber 40 may be formed in the oil chamber 32 of the accumulator as shown in FIG. it can. The second oil chamber 40 can be formed by being defined with the oil chamber 32 of the accumulator by a hydraulic piston 36. The hydraulic piston 36 has a cup shape in which a recess is formed around the central axis. This is to improve the slidability by reducing the mass of the hydraulic piston 36. The hydraulic piston 36 may be configured as a solid hydraulic piston without forming a recess.

  A spring 41 is disposed between the hydraulic piston 36 and the face plate 37 fixed to the end of the piston rod 4. The hydraulic piston 36 is biased toward the face plate 37 by the spring 41. The face plate 37 is fixed to the end of the piston rod 4 by fixing means such as screwing.

  The spring 41 performs the action of returning the hydraulic piston 36 to the face plate 37 side when the amount of pressure oil filled in the second oil chamber 40 decreases. However, when the amount of pressure oil in the oil chamber 40 decreases, the hydraulic piston 36 can return to the face plate 37 side by the oil pressure of the oil chamber 32 of the accumulator 12. For this reason, it is not always necessary to provide the spring 41. When the spring 41 is not provided, it is not always necessary to provide the face plate 37.

  An oil groove 36 a that connects the accumulator port 23 and the oil chamber 32 is formed in a part of the outer peripheral surface of the hydraulic piston 36. The oil groove 36 a is formed in parallel with the axial direction of the hydraulic piston 36. Thereby, even if the hydraulic piston 36 moves to the cylinder head side, the oil chamber 5a and the oil chamber 32 of the cylinder tube 2 can be communicated with each other by the accumulator port 23 and the oil groove 36a.

  Further, a cross-shaped oil groove 36 b communicating with the oil groove 36 a can be formed on the end face of the hydraulic piston 36. Even if the accumulator piston 13 is in close contact with the hydraulic piston 36 by the oil groove 36b, the accumulator piston is pressed and slid to the cylinder head side by the pressure oil from the oil chamber 5a of the cylinder tube 2. Can do.

  A hole for filling the oil chamber 40 with oil is formed in the vicinity of the face plate 37 side of the piston rod 4. The hole is sealed by an automatic opening / closing valve 38 disposed on the piston rod 4. The automatic opening / closing valve 38 is opened on the side of the hole 44 formed in the piston 3, and can come to a position facing the nipple 39 provided in the cylinder tube 2 at the stroke end of the piston rod 4.

  By removing the nipple 39 and connecting a pressure oil supply nozzle (not shown) to the automatic opening / closing valve 38, the oil chamber 40 can be filled with pressure oil, and the volume of the oil chamber 40 can be freely changed. it can. When the nipple 39 is closed, the automatic opening / closing valve 38 is positioned in the piston 3, so that the sliding of the piston 3 is not affected. In FIG. 10, a piston seal 43 is disposed between the hydraulic piston 36 and the piston rod 4.

  Thus, in the present invention, the volume of the gas chamber of the accumulator can be freely adjusted by the adjusting member, and the volume of the gas chamber can be adjusted with a very simple configuration. As a result, an optimal gas chamber volume corresponding to the hydraulic cylinder can be obtained.

  In the present invention, the technical idea of the present invention can be applied to various hydraulic cylinders in which an accumulator that absorbs an impact in the hydraulic cylinder is required to be disposed in the piston rod.

It is sectional drawing of a hydraulic cylinder. Example 1 It is sectional drawing which shows the other modification of a hydraulic cylinder. Example 1 It is sectional drawing which shows another modification of a hydraulic cylinder. Example 1 It is a principal part schematic sectional drawing of a hydraulic cylinder. (Example 2) It is a principal part schematic sectional drawing which shows the other modification of a hydraulic cylinder. (Example 2) It is a perspective view of a piston with a core. (Example 2) It is a principal part schematic sectional drawing of a hydraulic cylinder. Example 3 It is a principal part schematic sectional drawing which shows the other modification of a hydraulic cylinder. Example 3 It is a principal part schematic sectional drawing which shows another modification of a hydraulic cylinder. Example 3 It is a principal part schematic sectional drawing which shows another modification of a hydraulic cylinder. Example 3 It is sectional drawing of a hydraulic cylinder. (Conventional example 1) It is sectional drawing of a hydraulic cylinder. (Conventional example 2)

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Hydraulic cylinder, 2 ... Cylinder tube, 3 ... Piston,
4 ... piston rod, 6 ... cylinder head, 7 ... cylinder bottom, 10 ... plunger, 12, 12 '... accumulator,
DESCRIPTION OF SYMBOLS 13 ... Piston for accumulators 14 ... Core, 15 ... Connection member, 15c ... Supporting piece, 17 ... Piston with a core, 17b ... Core,
18 ... core, 20 ... balloon, 23 ... accum port,
25 ... second oil chamber, 26 ... second piston for oil chamber, 27 ... tube,
31 ... Gas chamber, 32 ... Oil chamber, 33 ... Pipe line,
36 ... Piston for hydraulic pressure, 37 ... Face plate, 40 ... Second oil chamber,
50 ... Cylinder device, 51 ... Cylinder body, 52 ... Piston,
53 ・ ・ ・ Piston rod, 56 ・ ・ ・ Air chamber, 57 ・ ・ ・ Diaphragm,
60 ... Cylinder, 62 ... Piston, 63 ... Space,
64 ・ ・ ・ Through hole, 66 ・ ・ ・ Ground, 67 ・ ・ ・ Accumulator piston, 68 ・ ・ ・ Spring, 73 ・ ・ ・ Piston rod.

Claims (2)

In a hydraulic cylinder with an accumulator in the piston rod,
An adjustment member is disposed in the piston rod,
By adjusting the volume of the accumulator by the volume of the adjustment member,
The adjusting member is constituted by a member of the volume fixed, Ri Na is disposed in the gas chamber or an oil chamber in the piston rod,
The hydraulic cylinder , wherein the adjusting member is a core disposed in a gas chamber or an oil chamber in the piston rod . The core, the piston via a minute clearance between the inner circumferential surface of the rod is fitted, and according to claim 1, characterized by comprising movably supported small relative to the piston axis Hydraulic cylinder.

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