JP2017078507A - Single rod type double-acting hydraulic cylinder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a single rod type double-acting hydraulic cylinder configured such that the area of a working oil receiving surface when a piston is moved to a head side is equal to the area of a working oil receiving surface when the piston is moved to a cap side.SOLUTION: A single rod type double-acting hydraulic cylinder 1 comprises a cylinder 2, a piston 3, a piston rod 4, and a core member 5. The piston is inserted and fitted in an in-cylinder space part 9. The piston rod is coupled to a rear end part of the piston, and extends outward penetrating a rear wall part 8 of the cylinder. The core member extends backward from a front wall part 7 of the cylinder. A hollow part 10 is formed in the piston rod, and the core member is fitted to the hollow part, a part of which forms a first oil chamber 11. The in-cylinder space part is partitioned off into a front part and a rear part by the piston, and a second oil chamber 15 is formed on a rear side of the piston. The single rod type double-acting hydraulic cylinder is configured such that the first oil chamber and the second oil chamber are equal in cross-sectional area.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a cylinder, a piston fitted in the cylinder inner space, a hollow piston coupled to the rear end of the piston and extending from the cylinder inner space through the rear wall of the cylinder to the cylinder outer space. The present invention relates to a single rod type double acting hydraulic cylinder provided with a rod.

  In general, a hydraulic cylinder in which a piston slidably fitted in a cylinder reciprocates by the pressure of hydraulic oil discharged from a hydraulic pump is a mechanical actuator that reciprocates similarly, such as a rack and pinion mechanism. Compared with a ball screw mechanism or the like, the structure is simple, the output is high, and the life is long. Therefore, it is widely used as an actuator for various mechanical devices and civil engineering construction vehicles. As one of such hydraulic cylinders, various single rod type double acting hydraulic cylinders having a simple structure and capable of hydraulically driving the piston in both directions of the cap side and the head side are known (for example, Patent Documents 1 to 3).

JP-A-10-110710 JP 2003-74518 A JP 2004-68863 A

  However, for example, as shown in FIG. 6, in the conventional single rod type double acting hydraulic cylinder 100, the piston rod 102 is attached to the end of the piston 101 on the head side. The pressure receiving area is smaller than the pressure receiving area on the cap side. If the pressure receiving area of the piston 101 is different between the head side and the cap side in this way, when the pressure of the hydraulic oil supplied from the hydraulic oil supply device 103 is constant, the piston is caused by the difference in the pressure receiving area. The force applied to the piston 101, and thus the moving speed of the piston 101, differs when the 101 moves to the cap side and when it moves to the head side. For this reason, there is a problem that the piston 101 cannot be used when the driving force or the moving speed in both directions is required to be the same.

  Further, since the cross-sectional areas of the oil chamber are different between the cap side and the head side, when supplying hydraulic oil to the cap side oil chamber 104 and when supplying hydraulic oil to the head side oil chamber 105, The amount of hydraulic oil supplied or discharged will be different. Specifically, when the piston 101 moves from the head side to the cap side, the amount of hydraulic oil for one stroke supplied from the hydraulic oil tank (not shown) of the hydraulic oil supply device 103 to the head side oil chamber 105. However, since the amount of hydraulic oil for one stroke discharged from the cap-side oil chamber 104 to the hydraulic oil tank is smaller, the holding amount (liquid level) of the hydraulic oil in the hydraulic oil tank increases.

  Conversely, when the piston 101 moves from the cap side to the head side, the amount of hydraulic oil for one stroke supplied from the hydraulic oil tank to the cap side oil chamber 104 is discharged from the head side oil chamber 105 to the hydraulic oil tank. The amount of hydraulic oil in the hydraulic oil tank (liquid level) decreases because the amount of hydraulic oil is larger than the amount of hydraulic oil for one stroke. As described above, in the conventional single rod type double acting hydraulic cylinder 100, the amount of hydraulic oil retained (liquid level) in the hydraulic oil tank fluctuates. Therefore, in order to cope with the variation in the amount of hydraulic oil retained, There is a problem that a large amount of hydraulic oil must be retained.

  For example, as shown in FIG. 7, in the double rod type double acting hydraulic cylinder 100 ′, a piston rod 106 having the same diameter as that of the piston rod 102 on the head side is also attached to the end of the piston 101 on the cap side. Therefore, the pressure receiving areas on the cap side and the head side of the piston 101 become equal, and the above-described problem does not occur. However, when the piston 101 moves to the cap side, the cap-side piston rod 106 largely protrudes outward from the cylinder-side wall 107 on the cap side as shown by a broken line, so that a wasted space is secured accordingly. There must be. For this reason, the double rod type double acting hydraulic cylinder 100 ′ has a problem different from the above problem that the layout of components such as a mechanical device to which the double rod type double acting hydraulic cylinder 100 ′ is mounted is greatly restricted.

  The present invention has been made in order to solve the above-described conventional problems, and the area of the pressure receiving surface of the hydraulic oil and the cap when moving the piston and the member (piston rod, etc.) connected thereto to the head side. It is an object to be solved to provide a single rod type double acting hydraulic cylinder having the same area of the pressure receiving surface of hydraulic oil when moved to the side.

  A single rod double acting hydraulic cylinder according to the present invention, which has been made to solve the above problems, includes a cylinder, a piston, a substantially cylindrical piston rod, and a substantially cylindrical core member. Here, the cylinder is connected to the substantially cylindrical peripheral wall portion, the front wall portion connected to the front end (cap-side end portion) of the peripheral wall portion, and the rear end (head-side end portion) of the peripheral wall portion. And a rear wall portion. The piston is fitted into a substantially cylindrical space in the cylinder formed in the cylinder, and can slide in the direction in which the cylinder central axis extends. The piston rod is coupled or connected to the rear end portion of the piston, and extends from the inner space portion of the cylinder through the rear wall portion to the outer space portion of the cylinder. The core member is connected or connected to the front wall at the front end, and along the direction in which the cylinder central axis extends, to the position of the rear wall or near the rear wall (the front side or the rear side of the rear wall ) To the rear.

  In this single rod type double acting hydraulic cylinder, a substantially cylindrical hollow portion is formed in the piston rod, and the outer peripheral surface of the core member is slidably fitted to the inner peripheral surface of the hollow portion. A portion on the rear side of the rear end surface of the core member forms a first oil chamber. The core member is provided with a first hydraulic oil port formed at the front end of the core member, and a core internal oil passage whose front end communicates with the first hydraulic oil port and whose rear end communicates with the first oil chamber. It has been. The in-cylinder space is partitioned forward and backward by the piston, and as a result, an air chamber located on the front side (cap side) of the piston and a second oil chamber located on the rear side (head side) of the piston are formed. . The cylinder is provided with an air port communicating with the air chamber and a second hydraulic oil port communicating with the second oil chamber. In this single rod type double acting hydraulic cylinder, the cross-sectional area of the first oil chamber (corresponding to the pressure-receiving area on the cap side) and the cross-sectional area of the second oil chamber (when corresponding to the cross section of the second oil chamber) (Corresponding to the pressure receiving area on the head side) is equal (same).

  In the single rod type double acting hydraulic cylinder according to the present invention, the air chamber is defined by the inner peripheral surface of the peripheral wall portion, the rear end surface of the front wall portion, the outer peripheral surface of the core member, and the front end surface of the piston. The The second oil chamber is defined by the inner peripheral surface of the peripheral wall portion, the front end surface of the rear wall portion, the outer peripheral surface of the piston rod, and the rear end surface of the piston. The air port is preferably provided at the front end portion of the peripheral wall portion, the vicinity thereof, or the front wall portion. It is preferable that the second hydraulic oil port is provided at the rear end portion of the peripheral wall portion, the vicinity thereof, or the rear wall portion.

  In the single rod double acting hydraulic cylinder according to the present invention, when pressurized hydraulic oil is supplied to the first oil chamber via the first hydraulic oil port and the oil passage in the core material, Due to the pressure of the hydraulic oil acting on the inner surface (front surface) of the end wall, a backward force is applied to the piston rod and thus the piston, and the piston and the piston rod are moved rearward. Thereby, a piston rod moves the member (load) connected with this backward. At this time, the hydraulic oil staying in the second oil chamber is discharged to the outside (for example, a hydraulic oil tank) via the second hydraulic oil port. At that time, external air is sucked into the air chamber via the air port.

  On the other hand, when pressurized hydraulic oil is supplied to the second oil chamber via the second hydraulic oil port, a forward force is applied to the piston and thus the piston rod due to the pressure of the hydraulic oil acting on the rear end surface of the piston. The piston and the piston rod are moved forward. Thereby, a piston rod moves the member (load) connected with this to the front. At this time, the hydraulic oil staying in the first oil chamber is discharged to the outside (for example, a hydraulic oil tank) through the core oil passage and the first hydraulic oil port. Air is discharged to the outside through the air port.

  In the single rod double acting hydraulic cylinder according to the present invention, the cross-sectional area of the first oil chamber is equal to the cross-sectional area of the second oil chamber when cut along a plane perpendicular to the cylinder central axis. Therefore, the area of the pressure receiving surface of the hydraulic oil when moving the piston and piston rod forward (cap side) and the area of the pressure receiving surface of the hydraulic oil when moving backward (head side) with pressurized hydraulic oil Is the same. For this reason, when the pressure of the supplied hydraulic oil and the load on the piston rod are constant, the force applied to the piston and the piston rod when the piston and the piston rod move forward and when the piston rod moves backward, and thus These moving speeds can be made equal. In addition, since the supply and discharge amount of the hydraulic oil to the first oil chamber or the second oil chamber are equal regardless of whether the piston and the piston rod move forward or backward, the hydraulic oil tank The amount of hydraulic oil retained can be reduced.

  Further, the core member extends rearward along the direction in which the center axis of the cylinder extends to the vicinity of the rear wall (front side or rear side of the rear wall), and the inner surface of the core member and the hollow portion (piston rod) Since the peripheral surface is slidably fitted, the core member and the hollow portion (piston rod) are in sliding contact with each other over a relatively long distance in the cylinder central axis direction. For this reason, the reciprocating movement of the piston and piston rod in the cylinder central axis direction is stabilized or smoothed (not jerky).

It is a typical elevation sectional view of a single rod type double acting hydraulic cylinder concerning the present invention in the state where a piston moved to the head side (back) to the maximum. (A) is the same figure as FIG. 1 in the state which moved the piston to the intermediate position, (b) is the same figure as FIG. 1 in the state which moved the piston to the cap side (front) to the maximum. is there. It is a figure which shows the shape thru | or dimension of the single rod type double acting hydraulic cylinder which concerns on this invention. FIG. 2 is a hydraulic circuit diagram showing a schematic configuration of a hydraulic oil supply device that supplies and discharges hydraulic oil to and from a single rod type double acting hydraulic cylinder shown in FIG. (A) is an elevation view of a single rod type double acting hydraulic cylinder that the applicant of the present invention intends to actually manufacture and sell the present invention, and (b) is a single rod type shown in (a). It is a bottom view of the elevation view of a double acting hydraulic cylinder. It is a schematic diagram which shows schematic structure of the conventional single rod type double acting hydraulic cylinder. It is a schematic diagram which shows schematic structure of a double rod type double acting hydraulic cylinder.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
As shown in FIGS. 1 and 2 (a) and 2 (b), a single rod double acting hydraulic cylinder 1 (hereinafter referred to as "hydraulic cylinder 1" for short) according to an embodiment of the present invention is a cylinder 2 ( A cylindrical tube), a substantially cylindrical piston 3, a hollow substantially cylindrical or substantially cylindrical piston rod 4, and a substantially cylindrical core member 5. In the following, in order to clearly show the positional relationship of each component in the hydraulic cylinder 1, the position on the cap side in the hydraulic cylinder 1 is referred to as “front” and the position on the head side is referred to as “rear”.

  The cylinder 2 has a substantially cylindrical peripheral wall portion 6, a front wall portion 7 coupled to the front end of the peripheral wall portion 6, and a rear wall portion 8 coupled to the rear end of the peripheral wall portion 6. The piston 3 is fitted into a substantially cylindrical space 9 in the cylinder formed in the cylinder 2, and can slide in the direction in which the cylinder central axis extends (front-rear direction). The piston rod 4 is coupled or coupled (fastened) to the rear end portion of the piston 3 and extends from the cylinder inner space portion 9 through the rear wall portion 8 in the front-rear direction to the cylinder outer space portion. The piston rod 4 is formed with a cylindrical hollow portion 10.

  The front end of the core member 5 is coupled or connected (fastened) to the front wall portion 7 and extends rearward to a position slightly forward of the rear wall portion 8 along the direction in which the cylinder center line extends (front-rear direction). . Here, the rear end surface 5 a of the core member 5 is positioned in front of the inner surface 8 a in the vicinity of the inner surface 8 a (front surface) of the rear wall portion 8. Further, the outer peripheral surface of the core member 5 is slidably fitted to the inner peripheral surface of the hollow portion 10 of the piston rod 4, and a portion of the hollow portion 10 on the rear side of the rear end surface 5 a of the core member 5 is a hydraulic cylinder. 1 first oil chamber 11 is formed. That is, the first oil chamber 11 includes an inner peripheral surface of the cylindrical peripheral wall 4 a of the piston rod 4, a circular inner surface (front surface) of the rear wall 4 b of the piston rod 4, and a circular rear end surface 5 a of the core member 5. It is defined by. The core member 5 may extend to the position of the rear wall portion 8 or a position behind (or slightly behind) the rear wall portion 8.

  As described above, since the rear end surface 5a of the core member 5 is positioned in front of the inner surface 8a in the vicinity of the inner surface 8a of the rear wall portion 8, the rear end surface 5a has the piston 3 maximally rearward (head side). ), The core member 5 and the hollow portion 10 can be slidably fitted to each other. Although not shown in the drawings, the rear surface of the piston 3 is provided with a locking member that locks the piston 3 from moving backward from the position shown in FIG. On the front surface of the piston 3, there is provided a locking member for locking the piston 3 from moving forward from the position shown in FIG.

  The front end of the core member 5 is provided with a first hydraulic oil port 12 for supplying and discharging hydraulic oil to and from the first oil chamber 11. Further, the core member 5 is provided with a core internal oil passage 13 that penetrates the core member 5 in the front-rear direction, the front end communicates with the first hydraulic oil port 12, and the rear end communicates with the first oil chamber 11. It has been. In this embodiment, the core member 5 has a solid structure except for a portion where the core oil passage 13 is formed. However, in order to reduce the weight of the core member 5, the core member 5 is closed in the solid structure. A space (closed hollow space) may be provided.

  The in-cylinder space 9 is partitioned forward and backward by the piston 3. As a result, the portion in front of the piston 3 in the in-cylinder space 9 forms the air chamber 14, and the portion in the rear of the piston 3 forms the second oil chamber 15 of the hydraulic cylinder 1. That is, the air chamber 14 is formed by the inner peripheral surface of the cylindrical peripheral wall portion 6, the annular rear end surface of the front wall portion 7, the outer peripheral surface of the cylindrical core member 5, and the annular front end surface of the piston 3. It is defined. The second oil chamber 15 includes an inner peripheral surface of the peripheral wall portion 6, an annular front end surface 8 a of the rear wall portion 8, an outer peripheral surface of the cylindrical peripheral wall 4 a of the piston rod 4, and an annular rear surface of the piston 3. It is defined by the end face.

  In the vicinity of the front end of the cylinder 2, an air port 16 communicating with the air chamber 14 is provided in the peripheral wall 6. Further, a second hydraulic oil port 17 communicating with the second oil chamber 15 is provided in the peripheral wall 6 in the vicinity of the rear end of the cylinder 2. Note that the air port 16 may be provided in the front wall portion 7. Further, the second hydraulic oil port 17 may be provided in the rear wall portion 8. During operation or operation of a mechanical device or the like equipped with the hydraulic cylinder 1, hydraulic oil always stays in the first oil chamber 11 and the second oil chamber 15. The air chamber 14 is always in communication with the atmosphere.

  Thus, as shown in FIG. 1, when the piston 3 is moved to the maximum rearward (head side), the pressurized hydraulic oil enters the second oil chamber 15 via the second hydraulic oil port 17. When supplied, a forward force is applied to the piston 3 and consequently the piston rod 4 by the pressure of the hydraulic oil acting on the annular rear end surface of the piston 3, and the piston 3 and the piston rod 4 are moved forward. At this time, the hydraulic oil staying in the first oil chamber 11 is discharged to the outside through the core material oil passage 13 and the first hydraulic oil port 12. The air in the air chamber 14 is discharged to the outside through the air port 16. As a result, the hydraulic cylinder 1 goes through an intermediate state as shown in FIG. 2A, and the piston 3 is moved forward as much as possible as shown in FIG. 2B. Thereby, the piston rod 4 moves the member (load) connected to the rear end portion forward.

  On the other hand, as shown in FIG. 2B, when the piston 3 is moved forward as much as possible, the pressurized hydraulic oil passes through the first hydraulic oil port 12 and the core oil passage 13. When the oil is supplied to the first oil chamber 11, a backward force is applied to the piston rod 4 and the piston 3 by the pressure of the hydraulic oil acting on the circular inner surface (front surface) of the rear wall 4 b of the piston rod 4. 3 and the piston rod 4 are moved backward. At this time, the hydraulic oil staying in the second oil chamber 15 is discharged to the outside through the second hydraulic oil port 17. Further, outside air is sucked into the air chamber 14 via the air port 16. As a result, the hydraulic cylinder 1 enters a state in which the piston 3 has moved to the maximum extent as shown in FIG. 1 through an intermediate state as shown in FIG. Thereby, the piston rod 4 moves the member (load) connected with the rear-end part backward.

  Thus, when the piston 3 and the piston rod 4 move in the front-rear direction in the cylinder 2, the piston rod 4 slides in a state of being fitted on the core member 5, so that the movement of the piston rod 4 in the front-rear direction is the center. Guided by the member 5, the piston rod 4 does not run out (sideways). That is, the core member 5 has a function as a guide member for the piston rod 4. In the conventional single rod type double acting hydraulic cylinder, a guide member for guiding the piston rod is generally provided outside the cylinder so as to prevent the piston rod from vibrating.

  In this hydraulic cylinder 1, the area of the circular cross section of the first oil chamber 11 and the area of the ring-shaped (ring-shaped) cross section of the second oil chamber 15 when cut along a plane perpendicular to the cylinder central axis are as follows. Are equal to each other. That is, the area of the hydraulic oil pressure surface when the piston 3 and the piston rod 4 are moved forward (cap side) by the pressurized hydraulic oil, and the hydraulic oil pressure surface when the piston 3 and the piston rod 4 are moved backward (head side). The area is the same. For this reason, when the pressure of the hydraulic oil supplied to the hydraulic cylinder 1 and the load applied to the piston rod 4 are constant, when the piston 3 and the piston rod 4 move forward and when moving backward, The forces applied to the piston 3 and the piston rod 4, and hence the moving speeds thereof, are equal.

  Further, the flow rate of the hydraulic oil supplied to the first oil chamber 11 or the second oil chamber 15 in any of the cases where the piston 3 and the piston rod 4 move forward and backward, and accordingly. The flow rates of the hydraulic oil discharged from the second oil chamber 15 or the first oil chamber 11 are equal to each other. As a result, since the amount of hydraulic oil stored in the hydraulic oil tank 21 of the hydraulic oil supply device 20 does not vary and is substantially constant, the capacity of the hydraulic oil tank 21 can be reduced as much as possible (FIG. 4).

  Further, as described above, in the conventional single rod type double acting hydraulic cylinder 100, the pressure receiving area of the piston 101 is different between the head side and the cap side, so when the piston 101 is moved to the cap side, it moves to the head side. The amount of hydraulic oil supplied and discharged differs depending on when In the conventional single rod type double acting hydraulic cylinder 100, the hydraulic oil is supplied so that a predetermined output or work is realized even in a stroke (stroke) with a smaller hydraulic oil supply / discharge amount. Therefore, hydraulic oil is supplied and discharged more than necessary in the stroke (stroke) in which the hydraulic oil is supplied and discharged. For this reason, in the conventional single rod type double acting hydraulic cylinder 100, the flow rate of the hydraulic pump or hydraulic oil becomes larger than necessary, and the amount of energy consumption increases accordingly. On the other hand, in the hydraulic cylinder 1 according to the present invention, the area of the hydraulic oil pressure receiving surface is the same when the piston 3 and the piston rod 4 are moved forward and when they are moved backward. It does not occur and wasteful consumption of energy can be prevented.

Hereinafter, with reference to FIG. 3, the hydraulic cylinder 1 is configured so that the cross-sectional area of the first oil chamber 11 and the cross-sectional area of the second oil chamber 15 are equal when cut along a plane perpendicular to the cylinder central axis. A basic method for setting the shape or dimension will be described. The specifications of the hydraulic cylinder 1 that need to be considered at that time are approximately as follows.
(A) Inner diameter D of the peripheral wall 6 of the cylinder 2
(B) The outer diameter d ₁ of the peripheral wall 4a of the piston rod 4
(C) Inner diameter d ₂ of the peripheral wall 4a of the piston rod 4
(D) Thickness t (= (d ₁ −d ₂ ) / 2) of the peripheral wall 4 a of the piston rod 4
(E) The outer diameter d ₃ (= d ₂ ) of the core member 5
(F) Length L of the piston rod 4

(1) In this method, first, the cross-sectional area S of the first oil chamber 11 (the same as the cross-sectional area of the second oil chamber 15) is determined according to the specifications of the hydraulic cylinder 1 or the specifications of the mechanical device to which it is mounted. , namely in terms of setting the pressure receiving areas S of the hydraulic fluid required to achieve the desired output, the following equation 1 for calculating the inner diameter d ₂ of the piston rod 4.
^{_{π · d 2 2/4 =}} S ..................................................................... formula 1
d ₂ : inner diameter of the peripheral wall 4a
S: Pressure receiving area

(2) Next, based on the buckling load of the piston rod 4 set in accordance with the specifications of the hydraulic cylinder 1 or the specifications of the mechanical device to which the hydraulic cylinder 1 is mounted, the circumferential wall 4a of the piston rod 4 is expressed by the following formula 2. The wall thickness t (= (d ₁ −d ₂ ) / 2) of the outer diameter d ₁ or the peripheral wall of the piston rod 4 is calculated.
^{F = n · π 2 · E} · I / L 2 = ((n · π 2 · E) / L 2) · (π (d 1 4 -d 2 4) / 64) ............ formula 2
F: Buckling load
n: Coefficient according to the mounting end condition (1/4 to 4)
E: Young's modulus of the material of the piston rod 4
I: Second moment of inertia of piston rod 4
L: Length of piston rod 4
d ₁ : outer diameter of the peripheral wall 4a
d ₂ : inner diameter of the peripheral wall 4a

(3) Further, based on the outer diameter d ₁ and the inner diameter d ₂ of the peripheral wall 4a that has already been calculated, the inner diameter D of the peripheral wall portion 6 of the cylinder 2 is calculated by the following equation 3.
^{_{π · (D 2 -d 1 2}} ) / 4 = π · d 2 2/4 .................................... formula 3
The outer diameter d ₃ of the core member is substantially equal to the inner diameter d ₂ of the peripheral wall 4a (to fitted a core member into the hollow portion, it is slightly smaller.). Further, the thickness of the peripheral wall portion 6 of the cylinder 2 is set in accordance with the specification of the hydraulic cylinder 1 or the specification of the mechanical device to which it is attached. Therefore, the outer diameter of the peripheral wall portion 6 is obtained by adding the thickness of the peripheral wall portion 6 to the inner diameter D of the peripheral wall portion 6. Thereby, the basic shape or dimension of the hydraulic cylinder 1 is determined. Incidentally, according to Equation 3, for example, the inner diameter _{d 2} is 60mm of the peripheral wall 4a of the piston rod 4, the outer diameter _{d 1} of the peripheral wall 4a of the piston rod 4 is at 80 mm (i.e., thickness of the peripheral wall 4a is 10 mm) In this case, the inner diameter D of the peripheral wall portion 6 of the cylinder 2 is 100 mm.

  Hereinafter, the schematic configuration and function of the hydraulic oil supply device 20 that supplies and discharges hydraulic oil to and from the hydraulic cylinder 1 will be described with reference to FIG. 4. The hydraulic oil supply device 20 includes a hydraulic oil tank 21 that stores hydraulic oil, a hydraulic oil passage 22 that includes a plurality of oil passages, and a hydraulic pump that is driven by an electric motor 23 (motor) or a prime mover (engine). 24 and an oil passage switching valve 25 provided in the hydraulic oil passage 22 are provided. The hydraulic oil passage 22 includes a first hydraulic path 26 that connects the first hydraulic oil port 12 of the hydraulic cylinder 1 and the oil path switching valve 25, a second hydraulic oil port 17 and the oil path switching valve 25 of the hydraulic cylinder 1, and And a second oil passage 27 for connecting the two.

  Further, the hydraulic oil passage 22 has a third oil passage 29 having one end connected to the oil passage switching valve 25 and the other end immersed in the hydraulic oil in the hydraulic oil tank 21 via the oil filter 28. . The hydraulic pump 24 is provided in the third oil passage 29, sucks the hydraulic oil in the hydraulic oil tank 21, pressurizes and discharges it, and supplies the hydraulic oil to the oil passage switching valve 25 through the third oil passage 29. . The hydraulic oil passage 22 includes a fourth oil passage 30 that returns the hydraulic oil from the oil passage switching valve 25 to the hydraulic oil tank 21, and a first oil passage 26 and a fourth oil passage that bypass the oil passage switching valve 25. The fifth oil passage 31 that connects 30, the third oil passage 29 (portion downstream from the hydraulic pump 24), and the fourth oil passage 30 (portion downstream from the connection portion with the fifth oil passage 31) are connected. And a sixth oil passage 32.

  The second oil passage 27 includes, in order from the oil passage switching valve 25 side toward the second hydraulic oil port 17 side, a check valve 33, a first check flow adjustment valve 34, and a second check flow adjustment valve. 35 is interposed. Further, a first relief valve 36 and a second relief valve 37 are interposed in the fifth oil passage 31 and the sixth oil passage 32, respectively.

  The hydraulic oil supply device 20 has one end connected to the air port 16 of the hydraulic cylinder 1 and the other end introduced into (inserted into) a space (in the air) above the hydraulic oil in the hydraulic oil tank 21. A passage 40 is provided. The air passage 40 returns mist or droplets of the hydraulic oil accompanying the air discharged from the air chamber 14 of the hydraulic cylinder 1 to the hydraulic oil tank 21 and prevents it from leaking outside. When the hydraulic oil in the second oil chamber 15 leaks to the air chamber 14 via the sliding contact portion between the piston 3 and the cylinder 2, the hydraulic oil returns to the hydraulic oil tank 21 via the air passage 40. .

  The oil path switching valve 25 switches the supply / discharge path of hydraulic oil to the hydraulic cylinder 1. Although not shown in detail, the oil passage switching valve 25 is a solenoid valve controlled by a control device (not shown), and hydraulic oil discharged from the hydraulic pump 24 is hydraulically supplied via the first oil passage 26. The first state of supplying to the first oil chamber 11 of the cylinder 1, the second state of supplying to the second oil chamber 15 of the hydraulic cylinder 1 through the second oil passage 27, and hydraulic oil to the hydraulic cylinder 1 Can be set to any of the third states in which no is supplied. In the first state, the hydraulic oil in the second oil chamber 15 returns to the hydraulic oil tank 21 via the second oil passage 27 and the fourth oil passage 30, and in the second state, the first oil The hydraulic oil in the oil chamber 11 returns to the hydraulic oil tank 21 through the first oil passage 26 and the fourth oil passage 30. Further, in the third state, the first oil passage 26 and the second oil passage 27 communicate with the fourth oil passage 30.

  Thus, in the hydraulic cylinder 1, hydraulic oil is supplied to the first oil chamber 11 via the first oil passage 26 and the like, while the hydraulic oil in the second oil chamber 15 is supplied via the second oil passage 27 and the like. When discharged, the piston 3 and the piston rod 4 are moved rearward (head side) by hydraulic pressure. On the other hand, when the hydraulic oil is supplied to the second oil chamber 15 through the second oil passage 27 and the like, while the hydraulic oil in the first oil chamber 11 is discharged through the first oil passage 26 and the like, the piston 3 and the piston rod 4 are moved forward (cap side) by hydraulic pressure.

  As described above, in the hydraulic cylinder 1, the hydraulic oil supplied to the first oil chamber 11 or the second oil chamber 15 regardless of whether the piston 3 and the piston rod 4 move forward or backward. And the flow rate of hydraulic oil discharged from the second oil chamber 15 or the first oil chamber 11 along with this flow rate, the amount of hydraulic oil retained in the hydraulic oil tank 21 (liquid level) Does not change and is almost constant. For this reason, in the hydraulic pressure supply device 20, the capacity of the hydraulic oil tank 21 can be made as small as possible. Further, as described above, the area of the hydraulic oil pressure receiving surface is the same when the piston 3 and the piston rod 4 are moved forward and backward, so that the flow rate of the hydraulic pump 24 or hydraulic oil is more than necessary. It is not increased, and wasteful consumption of energy can be prevented.

  Further, the core member 5 extends rearward in the front-rear direction (direction in which the cylinder central axis extends) to the position of the rear wall 8 or its vicinity (front side or rear side from the rear wall 8), and the outer peripheral surface of the core member 5 And the inner peripheral surface of the hollow portion 10 (piston rod 4) are slidably fitted, so that the core member 5 and the hollow portion 10 (piston rod 4) are over a relatively long distance in the cylinder central axis direction. Make sliding contact. For this reason, the reciprocating movement of the piston 3 and the piston rod 4 in the cylinder central axis direction is stabilized or smoothed (not jerky).

5 (a) and 5 (b) show a single rod type double acting hydraulic cylinder which the applicant of the present application intends to actually manufacture and sell by implementing the present invention. The main specifications of the single rod type double acting hydraulic cylinder 1 are as follows. The single rod type double acting hydraulic cylinder 1 includes a connecting rod 50 for connecting the piston rod 4 and various devices to be driven by the single rod type double acting hydraulic cylinder 1, and the single rod type double acting. A flange 51 for fixing the hydraulic cylinder 1 to the fixing portion is provided.
(A) Total hydraulic cylinder length: 930 mm
(B) Cylinder inner diameter D: 150 mm
(C) Piston rod outer diameter d ₁ : 120 mm
(D) Piston rod inner diameter d ₂ : 90 mm
(E) First oil chamber cross-sectional area: 6360 mm ²
(F) Second oil chamber cross-sectional area: 6360 mm ²
(G) Maximum operating pressure: 7 MPa
(H) Hydraulic oil: General mineral hydraulic oil (i) Mass: 150 kg

  1 single rod type double acting hydraulic cylinder, 2 cylinder, 3 piston, 4 piston rod, 5 core member, 6 peripheral wall, 7 front wall, 8 rear wall, 9 cylinder internal space, 10 hollow, 11 1st Oil chamber, 12 First hydraulic oil port, 13 Core member internal oil passage, 14 Air chamber, 15 Second oil chamber, 16 Air port, 17 Second hydraulic oil port, 20 Hydraulic oil supply device, 21 Hydraulic oil tank, 22 Hydraulic oil passage, 23 Electric motor (motor), 24 Hydraulic pump, 25 Oil passage switching valve, 26 First oil passage, 27 Second oil passage, 28 Oil filter, 29 Third oil passage, 30 Fourth oil passage, 31 5 oil passage, 32 6th oil passage, 33 check valve, 34 flow check valve with first check, 35 flow control valve with second check, 36 first relief valve, 37 second relief valve, 40 air passage, 50 Connector, DESCRIPTION OF SYMBOLS 1 Flange, 100 Conventional single rod type double acting hydraulic cylinder, 100 'Double rod type double acting hydraulic cylinder, 101 Piston, 102 Piston rod, 103 Hydraulic oil supply device, 104 Cap side oil chamber, 105 Head side oil chamber, 106 Piston rod, 107 Cylinder end wall.

Claims (3)

A cylinder having a substantially cylindrical peripheral wall, a front wall connected to the front end of the peripheral wall, and a rear wall connected to the rear end of the peripheral wall;
A piston that is fitted into a substantially cylindrical space in the cylinder formed in the cylinder and can slide in a direction in which the cylinder central axis extends;
A substantially cylindrical piston rod coupled to a rear end portion of the piston and extending from the inner space portion of the cylinder to the outer space portion of the cylinder through the rear wall portion;
A substantially cylindrical core member having a front end coupled to the front wall portion and extending rearwardly to a position of the rear wall portion or a position in the vicinity of the rear wall portion along a direction in which a cylinder central axis extends. A single rod type double acting hydraulic cylinder,
A substantially cylindrical hollow portion is formed in the piston rod,
The outer peripheral surface of the core member is slidably fitted to the inner peripheral surface of the hollow portion, and the rear portion of the hollow portion from the rear end surface of the core member forms a first oil chamber,
The core member is provided with a first hydraulic oil port formed at the front end of the core member, and a core internal oil passage whose front end communicates with the first hydraulic oil port and whose rear end communicates with the first chamber. And
The in-cylinder space is partitioned forward and backward by the piston to form an air chamber located on the front side of the piston and a second oil chamber located on the rear side of the piston;
The cylinder is provided with an air port communicating with the air chamber and a second hydraulic oil port communicating with the second oil chamber,
A single-rod double-acting hydraulic cylinder characterized in that a cross-sectional area of the first oil chamber and a cross-sectional area of the second oil chamber are the same when cut along a plane perpendicular to the cylinder central axis. The air chamber is defined by an inner peripheral surface of the peripheral wall portion, a rear end surface of the front wall portion, an outer peripheral surface of the core member, and a front end surface of the piston,
The second oil chamber is defined by an inner peripheral surface of the peripheral wall portion, a front end surface of the rear wall portion, an outer peripheral surface of the piston rod, and a rear end surface of the piston. The single rod type double acting hydraulic cylinder according to claim 1. The air port is provided at or near the front end of the peripheral wall or the front wall.
3. The single-rod double acting hydraulic cylinder according to claim 1, wherein the second hydraulic oil port is provided in a rear end portion of the peripheral wall portion, in the vicinity thereof, or in the rear wall portion.

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