JP2011133007A - Fluid pressure cylinder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fluid pressure cylinder of satisfactory operability, capable of enhancing the operating pressure of a working fluid. <P>SOLUTION: This fluid pressure cylinder includes a cylinder body 22 having an end plate 21 in one end and opened in the other end, a pipe 23 arranged coaxially inside the cylinder body 22 and having one end penetrated through the end plate 21, a piston 24 fit slidably around the pipe 23 and inscribed slidably onto the cylinder body 22, a cylindrical rod 25 having one end adjacent to the piston 24, inscribed slidably onto the cylinder body 22, and having the other end projected outwards from the other end opening of the cylinder body 22, an end plate 26 adjacent to the other end of the pipe 23 and inscribed onto the rod 25 to slide the rod 25, the first fluid passage 28 for imparting the fluid pressure from the outside to a head side fluid chamber 27, and the second fluid passage 30 communicated with a rod side fluid chamber 29 from the other end of the pipe 23. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a fluid pressure cylinder.

  Fluid pressure cylinders are used as driving sources for various machines and equipment. FIG. 2 shows an example of a conventional fluid pressure cylinder. A cylinder body 2 having a head-side end plate 1 at one end and an opening at the other end, and a piston 3 slidably inscribed in the cylinder body 2. And an annular end plate 4 attached to the other end of the cylinder body 2, and a base end fixed to the piston 3 and slidably penetrating the end plate 4 so that the tip protrudes outward of the cylinder body 2. And a rod 5 to be used.

  At one end of the cylinder body 2, a first fluid passage 7 communicating from the outside of the cylinder body 2 is drilled into the head side fluid chamber 6 surrounded by the inner surface of the cylinder body 2, the end plate 1 on the head side, and the piston 3. Has been. The other end of the cylinder body 2 has a second fluid passage 9 communicating with the rod-side fluid chamber 8 surrounded by the inner surface of the cylinder body 2, the rod-side end plate 4, and the piston 3 from the outside of the cylinder body 2. Is drilled.

  10 and 11 are seal members fitted to the piston 3, and 12 is a seal member fitted to the hole 4a of the end plate 4 on the rod side. A clevis 13 is attached to the end plate 1 on the head side, and a boom of a hydraulic excavator is connected to the clevis 13. Reference numeral 14 denotes an eye attached to the tip of the rod, and an arm or the like pivotally supported on the boom is connected to the eye 14.

  In this fluid pressure cylinder, when a working fluid having a predetermined pressure is supplied to the first fluid passage 7 in a state where the piston 3 is positioned near the end plate 1 on the head side, the head is passed through the first fluid passage 7. Fluid pressure is applied to the inside of the side fluid chamber 6, the piston 3 moves toward the end plate 4 on the rod side, the rod 5 protrudes from the cylinder body 2, and the working fluid inside the rod side fluid chamber 8 is the second fluid. It is sent out from the fluid passage 9 to the outside.

  On the other hand, when a working fluid having a predetermined pressure is supplied to the second fluid passage 9 in a state where the piston 3 is located near the end plate 4 on the rod side, the rod-side fluid chamber is supplied from the second fluid passage 9. The fluid pressure is applied to the inside of the cylinder 8, the piston 3 moves toward the end plate 1 on the head side, the rod 5 is drawn into the cylinder body 2, and the working fluid in the head side fluid chamber 6 is moved to the first fluid passage. 7 to the outside.

  The pressure receiving area of the rod-side fluid chamber 8 of the piston 3 is smaller by the cross-sectional area of the rod 5 than the head-side fluid chamber 6 of the piston 3. For this reason, the force (tensile load) when the rod 5 is pulled into the cylinder body 2 is weaker than the force (extrusion load) when the rod 5 is projected from the cylinder body 2, and the rod 5 is pulled into the cylinder body 2. The moving speed when the rod 5 is moved is faster than the moving speed when the rod 5 is projected from the cylinder body 2. Further, when the rod 5 is drawn into the cylinder body 2, the working fluid delivered from the head side fluid chamber 6 becomes excessive with respect to the pipe diameter set in accordance with the working fluid discharge amount of the pump, and is caused by the flow path resistance. Causes energy loss.

  In addition, an actuator drive circuit having a reverse operation acceleration circuit that synchronizes and reverses the reverse operation of the rods of the first hydraulic cylinder and the second hydraulic cylinder (the movement of the rod being pulled into the cylinder) has been proposed ( For example, see Patent Document 1).

JP 2009-162257 A

  If the working pressure of the working fluid supplied to the head side fluid chamber 6 and the rod side fluid chamber 8 is increased, the pressure receiving area of the piston 3 can be reduced, and the cylinder body 2 and the piston 3 can be reduced in diameter. The rod 5 is required to have a secondary moment of inertia that can withstand a buckling load regardless of the working pressure of the working fluid, so there is a limit to reducing the diameter of the rod 5.

  That is, in a fluid pressure cylinder that has a predetermined stroke and is used under a constant load condition, the diameter of the rod 5 cannot be changed, so that the outer diameter of the piston 3 and the inner diameter of the cylinder body 2 are reduced. The ratio of the pressure receiving area of the rod side fluid chamber 8 to the pressure receiving area of the head side fluid chamber 6 of the piston 3 is further reduced.

  Therefore, the difference between the pushing load and the tensile load of the rod 5 and the difference between the moving speed when the rod 5 is projected and the moving speed when the rod 5 is retracted are further widened, and good operability cannot be obtained.

  The thing of patent document 1 is a precondition that the rod of two hydraulic cylinders is connected indirectly or directly, and cannot apply to a hydraulic cylinder single-piece | unit.

  The present invention has been made in view of the above-described circumstances, and an object thereof is to provide a fluid pressure cylinder that has good operability and can increase the working pressure of a working fluid.

  In order to achieve the above object, in the fluid pressure cylinder according to claim 1, a cylinder body having a head-side end plate at one end and an opening at the other end, a coaxial body disposed in the cylinder body, and one end thereof A pipe penetrating the end plate, a piston slidably fitted in the pipe and slidably inscribed in the cylinder body, and one end connected to the piston and slidably inscribed in the cylinder body And a hollow rod projecting outward from the other end opening of the cylinder main body, a rod-side end plate connected to the other end of the pipe and inscribed in the rod so that the rod can slide, A cylinder body inner surface, a head side end plate, a first fluid passage communicating from the outside of the cylinder body to a head side fluid chamber surrounded by the piston, a rod inner surface from the other end of the pipe, a rod side end plate, and On the piston And a second fluid passage communicating with the rod side fluid chamber surrounded me.

  The fluid pressure cylinder according to claim 2 has a configuration in which a proximal-side connector is attached to an end plate at one end of the cylinder body, and a distal-end connector is attached to the other end of the cylindrical rod. In the fluid pressure cylinder described in 1), the other end of the cylindrical rod is closed by the distal end side connector, and the air passage that communicates with the outside the rod inner surface, the rod side end plate, and the space surrounded by the distal end side connector. Is provided on the distal end side connector.

  According to the fluid pressure cylinder of the present invention, the following excellent effects can be obtained.

  (1) The cylindrical rod connected to the piston has a large outer diameter, a sufficient moment of inertia is obtained, and it can withstand a buckling load equal to or greater than that of the conventional rod-shaped rod. The difference between the pressure-receiving area of the head-side fluid chamber and the pressure-receiving area of the rod-side fluid chamber can be reduced, and the tensile load when the rod is pulled into the cylinder body and the extrusion load when the rod is projected from the cylinder body And the difference between the moving speed when the rod is pulled into the cylinder body and the moving speed when the rod is protruded from the cylinder body are reduced, and good operability is obtained.

  (2) Since rods with sufficient secondary moment of inertia have a small cross-sectional area, the cylinder body's inner and outer diameters, piston outer diameter and rod inner and outer diameters are reduced to reduce the size and size of the hydraulic cylinder. Even when the working pressure of the fluid is increased, the ratio of the pressure receiving area of the rod-side fluid chamber to the pressure receiving area of the piston head-side fluid chamber does not change so much, and the above-described good operability is not impaired.

It is a conceptual diagram which shows an example of the fluid pressure cylinder of this invention. It is a conceptual diagram which shows an example of the conventional fluid pressure cylinder.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 shows an example of a fluid pressure cylinder according to the present invention. A cylinder body 22 having a head-side end plate 21 at one end and an opening at the other end is coaxially disposed and fixed in the cylinder body 22. A pipe 23 having one end penetrating the end plate 21, an annular piston 24 slidably fitted to the pipe 23, and slidably inscribed in the cylinder body 22, and one end connected to the piston 24 A cylindrical rod 25 that is slidably inscribed in the cylinder body 22 and has the other end protruding outward from the opening of the other end of the cylinder body 22, and is connected to the other end of the pipe 23 and the rod 25 slides. In addition, a rod-side end plate 26 inscribed in the rod 25 is provided.

  A first fluid passage 28 communicating from the outside of the cylinder body 22 is formed in one end portion of the cylinder body 22 in a head side fluid chamber 27 surrounded by the inner surface of the cylinder body 22, the end plate 21 on the head side, and the piston 24. Has been. The rod-side end plate 26 has a second fluid passage 30 communicating from the other end of the pipe 23 to the rod 25 inner surface, the rod-side end plate 26, and the rod-side fluid chamber 29 surrounded by the piston 24. It has been drilled.

  Since the pipe 23 is not subjected to a bending load, the pipe 23 only needs to have a channel cross-sectional area corresponding to the flow rate of the working fluid entering and exiting the rod side fluid chamber 29 and a wall thickness that can withstand the working pressure of the working fluid.

  31 is a seal member fitted to the piston 24, 32 and 33 are seal members fitted to the holes 24a of the piston 24, and 34 is a seal member fitted to the end plate 26. Reference numeral 35 denotes a clevis attached to the end plate 21 on the head side, and a boom of an excavator is connected to the clevis 3521. Reference numeral 36 denotes an eye attached to the tip of the rod, and an arm or the like pivotally supported on the boom is connected to the eye 36. The eye 36 is formed with an air passage 38 that communicates the inner surface of the rod 25, the end plate 26 on the rod side, and a space 37 surrounded by the eye 36 to the outside.

  In the fluid pressure cylinder shown in FIG. 1, when a working fluid having a predetermined pressure is supplied to the first fluid passage 28 in a state where the piston 24 is positioned near the end plate 21 on the head side, the first fluid passage is provided. A fluid pressure is applied from 28 to the inside of the head-side fluid chamber 27. As a result, the piston 24 moves toward the end plate 26 on the rod side, the rod 25 protrudes from the cylinder body 22, and the working fluid inside the rod side fluid chamber 29 flows from the second fluid passage 30 and the pipe 23 to the outside. Sent out. At this time, the void 37 expands as the rod 25 moves, and air outside the fluid pressure cylinder flows into the void 37 through the air passage 38.

  On the contrary, when a working fluid having a predetermined pressure is supplied to the pipe 23 in a state where the piston 24 is positioned near the end plate 26 on the rod side, the rod side fluid chamber 29 is supplied from the pipe 23 and the second fluid passage 30. Fluid pressure is applied to the inside. As a result, the piston 24 moves toward the end plate 21 on the head side, the rod 25 is drawn into the cylinder body 22, and the working fluid inside the head side fluid chamber 27 is sent out from the first fluid passage 28 to the outside. The At this time, the space 37 narrows as the rod 25 moves, and the air in the space 37 flows out of the fluid pressure cylinder through the air passage 38.

  In the fluid pressure cylinder shown in FIG. 1, the difference between the pressure receiving area in the head-side fluid chamber 27 of the piston 24 and the pressure receiving area in the rod-side fluid chamber 29 is the sectional area of the cylindrical rod 25 connected to the piston 24. Equivalent to. Since the outer diameter of the rod 25 is the same as that of the piston 24 and a sufficient moment of inertia is obtained, the rod 25 can withstand a buckling load equal to or greater than that of a solid rod-shaped rod. Therefore, the difference between the pressure receiving area of the head-side fluid chamber 27 of the piston 24 and the pressure receiving area of the rod-side fluid chamber 29 is smaller than when a solid rod-shaped rod is used.

  Since the pipe 23 passes through both the head side fluid chamber 27 and the rod side fluid chamber 29 in the cylinder body 22, the pipe 23 itself is connected to the pressure receiving area of the head side fluid chamber 27 of the piston 24 and the rod side fluid chamber. The difference from the pressure receiving area of 29 is not affected.

  Therefore, the difference between the force (tensile load) when the rod 25 is pulled into the cylinder body 22 and the force (extrusion load) when the rod 25 is projected from the cylinder body 22, and the rod 25 is pulled into the cylinder body 22. The difference between the moving speed when the rod 25 is pushed out and the moving speed when the rod 25 is protruded from the cylinder body 22 is reduced compared with the case where a solid rod-like rod having a smaller outer diameter than the piston 24 is used. Sex is obtained.

  Further, since the difference between the pressure receiving area of the rod-side fluid chamber 29 of the piston 24 and the head-side fluid chamber 27 becomes small, the operation that is sent out from the head-side fluid chamber 27 when the rod 25 is pulled into the cylinder body 22. The excess of the fluid flow rate with respect to the pipe diameter set in accordance with the discharge amount of the working fluid of the pump is reduced, and energy loss due to flow path resistance is reduced.

  Further, since the rod 25 having a sufficient moment of inertia in section has a small sectional area from the beginning, the inner and outer diameters of the cylinder body 22, the outer diameter of the piston 24, and the inner and outer diameters of the rod 25 are reduced to reduce the size of the fluid pressure cylinder. Even if the working pressure of the working fluid is increased, the ratio of the pressure receiving area of the rod side fluid chamber 29 to the pressure receiving area of the head side fluid chamber 27 of the piston 24 does not change so much, and the above-described good operability is not impaired. .

  It should be noted that the fluid pressure cylinder of the present invention is not limited to the above-described embodiment, and it is needless to say that changes can be made without departing from the gist of the present invention.

21 End plate 22 Cylinder body 23 Piping 24 Piston 25 Rod 26 End plate 27 Head side fluid chamber 28 First fluid passage 29 Rod side fluid chamber 30 Second fluid passage

Claims (3)

A cylinder body having an end plate on the head side at one end and the other end opened;
A pipe disposed coaxially in the cylinder body and having one end penetrating the end plate;
A piston slidably fitted to the pipe and slidably inscribed in the cylinder body;
A hollow rod having one end connected to the piston and slidably inscribed in the cylinder body, and the other end protruding outward from the other end opening of the cylinder body;
A rod-side end plate that is continuous with the other end of the pipe and that is inscribed in the rod so that the rod can slide;
A first fluid passage communicating from the outside of the cylinder body to a cylinder body inner surface, a head side end plate, and a head side fluid chamber surrounded by the piston;
A fluid pressure cylinder comprising: a second fluid passage communicating from the other end of the pipe to a rod inner surface, a rod side end plate, and a rod side fluid chamber surrounded by a piston. Attach the proximal connector to the end plate of one end of the cylinder body,
The fluid pressure cylinder according to claim 1, wherein a distal end side connecting tool is attached to the other end of the cylindrical rod.   The other end of the cylindrical rod is closed by the distal end side coupling tool, and an air passage is provided in the distal end side coupling tool to communicate the inside of the rod, the end plate on the rod side, and the space surrounded by the distal end side coupling tool to the outside. The fluid pressure cylinder according to claim 2.

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