JP5315193B2 - Double acting hydraulic cylinder - Google Patents

Description

  The present invention relates to a double-acting hydraulic cylinder that uses a hydraulic pressure to actuate a piston that operates a punch up and down when drilling a workpiece placed on a die with a hydraulically operated drilling machine, for example. It is.

  Conventional double-acting hydraulic cylinders use a solenoid valve or a manual switching valve to switch the reciprocating motion of the piston. For example, as shown in Japanese Patent No. 3712260, there are two drive parts for pumping oil for forward movement. Such double-acting hydraulic cylinders require peripheral equipment for operating the solenoid valve or need to provide pumps at two locations. The double-acting hydraulic cylinder itself is difficult to reduce in size and weight because of its complicated structure and a large number of parts. Therefore, it is difficult to reduce the size of the hydraulically operated processing machine using this. There was a problem.

  In view of this, the present inventor has proposed a double-acting hydraulic cylinder that solves the above-described problems and is miniaturized without using a solenoid valve or a manual switching valve, as in Japanese Patent No. 3615183.

Japanese Patent No. 3712260 Japanese Patent No. 3615183

  However, even in the double acting hydraulic cylinder of Japanese Patent No. 3615183 devised by the present inventor, the pressure oil moving path is still complicated and the number of parts is still large, so that in terms of productivity, Have many problems.

  Therefore, the present invention simplifies the complicated pressure oil movement path of the conventional double-acting hydraulic cylinder and simplifies the structure by reducing the number of parts, making it smaller and lighter, inexpensive and excellent in mass productivity. It aims to provide an innovative double-acting hydraulic cylinder.

  The gist of the present invention will be described with reference to the accompanying drawings.

  In a double-acting hydraulic cylinder that supplies pressure oil into a cylinder chamber to operate the piston 1 up and down, the piston chamber 1 divides the cylinder chamber to provide a first cylinder chamber 2 on one side and a second cylinder on the opposite side. The chamber 3 and the third cylinder chamber 4 are provided, pressure oil is supplied to the first cylinder chamber 2, and the valve body 5 is provided in the piston 1 that moves forward by the oil pressure of the pressure oil. A first valve portion 7 is provided for switching the first cylinder chamber 2 and the first series chamber 6 serving as a path for discharging the pressure oil from the first cylinder chamber 2 between a communication state and a closed state, and a drive unit. A second communication chamber 9 serving as a path for supplying pressurized oil from the side supply path 8 to the first cylinder chamber 2 through the second cylinder chamber 3 is provided. A valve body supply path 10 is provided as a path for supplying pressurized oil to the chamber 2. This valve body supply path 10 and the second communication chamber 9 are provided with a second valve portion 11 for switching between a communication state and a closed state, and when the piston 1 moves forward, the valve 1 is retracted to obtain a spring force to obtain this spring. An opening spring 12 that pushes up the valve body 5 by force is provided on the inner surface of the valve body 5 or the third cylinder chamber 4 facing the valve body 5, and the valve body 5 is pushed upward by the opening spring 12. When the first valve portion 7 is opened, the first cylinder chamber 2 and the first communication chamber 6 are in communication with each other, and the valve body 5 is closed so that the second valve portion 11 is closed. The valve body 5 is pushed upward by the operation of the release spring 12, the second valve portion 11 is closed, and the supply of pressure oil to the first cylinder chamber 2 is stopped. Is switched to the second cylinder chamber 3 and pressure oil is supplied into the second cylinder chamber 3. Is, it relates to a double acting hydraulic cylinder, wherein the piston 1 moves back pushed up by oil pressure of the hydraulic oil gel pushed the upper inner surface of the second cylinder chamber 3.

  The first cylinder chamber 2 has the upper surface of the piston 1 as the bottom surface, and the third cylinder chamber 4 has the lower surface of the piston 1 as the upper surface, and contacts the upper surface and the lower inner surface of the third cylinder chamber 4. A piston return spring 13 is provided so that a force for pushing up the piston 1 is applied. The second cylinder chamber 3 is positioned between the first cylinder chamber 2 and the third cylinder chamber 4. The double-acting hydraulic cylinder according to claim 1, wherein a concave portion is formed along the circumferential surface of the piston 1.

  The concave portion is formed along the peripheral surface of the piston 1, and the area of the upper surface of the concave portion is set larger than the area of the lower surface. This relates to the double-acting hydraulic cylinder described in 1.

  Further, the opening spring 12 is provided with two or more springs having different expansion / contraction forces, and is configured such that when the piston 1 moves forward, the spring having a low expansion / contraction force is first retracted, and the expansion / contraction force is low. 4. The structure according to claim 1, wherein when the valve body cannot be pushed up by a spring, a spring having a stronger expansion / contraction force than the spring having a lower expansion / contraction force is in a contracted state. This relates to the double-acting hydraulic cylinder described.

  Further, the opening spring 12 is composed of a first opening spring 14 and a second opening spring 15 having different expansion / contraction forces, and the first opening spring 14 moves into a retracted state when the piston 1 moves forward to obtain a spring force, and The second opening spring 15 has a stretching force stronger than the stretching force of the first opening spring 14 and has a stretching force that expands when the spring force becomes larger than the oil pressure acting on the upper surface of the piston 1. The first opening spring 14 and the second opening spring 15 are connected to the first opening spring 14 downward, or the length of the first opening spring 14 is longer than the length of the second opening spring 15. 5. The double-acting hydraulic cylinder according to claim 1, wherein the double-acting hydraulic cylinder is long and concentrically provided.

  Further, the piston 1 moves backward, the upper end portion of the valve body 5 comes into contact with the upper inner surface of the first cylinder chamber 2, and the first valve portion 7 moves downward. 7 and the joint portion 16 of the piston 1 joined to the first valve portion 7 are gradually narrowed to form a constricted portion 17 that narrows the path of the pressure oil, and the constricted portion 17 forms the first cylinder. Since the discharge speed of the pressure oil from the chamber 2 to the first communication chamber 6 decreases and the oil pressure in the first cylinder chamber 2 increases, the oil pressure in the first cylinder chamber 2 and the piston The constricted portion so that the sum of the oil pressure acting on the upper surface of the second cylinder chamber 3 that causes the piston 1 to move backward and the spring force of the piston return spring 13 is in an equilibrium state and the piston 1 stops moving backward. The double-acting oil according to any one of claims 1 to 5, wherein 17 is set. This relates to the pressure cylinder.

  Further, the constricted portion 17 is configured such that the piston 1 moves backward, the first valve portion 7 is pushed downward, and the facing distance between the lower horizontal surface of the first valve portion 7 and the upper horizontal surface of the joint portion 16 is increased. When the first narrowed portion is formed by narrowing, the lower vertical surface of the first valve portion 7 and the side surface of the joint portion 16 face each other, and the first valve portion 7 The narrowed portion 17 is provided in which the lower vertical surface and the side surface of the joint portion 16 form a second constricted portion having a narrower facing distance than the first constricted portion, and the pressure oil path becomes a narrow shape. The double-acting hydraulic cylinder according to claim 1, wherein:

  When the valve body 5 is pushed upward by the release spring 12 and the first valve portion 7 is opened, and the first cylinder chamber 2 and the first communication chamber 6 are in communication with each other, The double-acting hydraulic pressure according to any one of claims 1 to 7, wherein an open holding spring 18 is provided for maintaining a communication state between the first cylinder chamber 2 and the first communication chamber 6. It concerns the cylinder.

  Since the present invention is configured as described above, the piston is moved forward by the hydraulic pressure of the pressure oil, and when the piston reaches the lowest point, the release spring pushes up the valve body to automatically provide the valve body. Since the respective valve states are switched, the operation is smoothly switched to the backward operation. Further, during the backward operation, the pressure oil is supplied to the second cylinder chamber, and the piston is moved backward by the oil pressure of the pressure oil. However, the number of parts can be greatly reduced by adopting a configuration in which the pressure oil supply destination can be switched with a single valve body, and a supply path has been provided in the valve body. Thus, the cylinder chamber can be reduced in size and weight, and the revolutionary double-acting hydraulic cylinder is excellent in practicality, and has a simple configuration and excellent productivity that can be easily realized.

  Further, in the invention according to claim 2, since the second cylinder chamber is provided by forming a recess in the peripheral surface of the piston, it is possible to further reduce the size with a simple configuration, and particularly in the invention according to claim 3. When the pressure oil is supplied to the second cylinder chamber, the oil pressure of the pressure oil and the spring force of the piston return spring act in the direction of pushing the piston upward, so the piston can be configured with a very simple configuration. This is an excellent double-acting hydraulic cylinder that is extremely suitable for reducing the size and weight of a cylinder that can reliably return.

  Further, in the inventions according to claims 4 and 5, since the upward movement of the valve body when the piston is moved backward can be performed more reliably, the operation from the forward movement to the backward movement can be performed stably. It becomes a double-acting hydraulic cylinder with excellent utility for switching.

  In the inventions of claims 6 and 7, even if the pressure oil is continuously supplied, the piston finishes moving backward and does not move forward again. Check the state of the piston and check the operation switch. There is no need for operation, and a double-acting hydraulic cylinder with even more practicality that can be easily operated and can secure safety during operation is obtained.

  In the invention according to claim 8, since the valve body can be kept pushed upward by the release spring, the piston is surely returned and can be operated stably. A double acting hydraulic cylinder.

It is explanatory sectional drawing which shows the state at the time of the piston forward movement start of a present Example. It is explanatory sectional drawing which shows the state at the time of the end of piston forward movement of a present Example. It is explanatory sectional drawing which shows the state at the time of the piston backward movement start of a present Example. It is explanatory sectional drawing which shows the state at the time of the piston backward movement end of a present Example. It is a description perspective view which shows the piston of a present Example. It is explanatory sectional drawing which shows the 2nd cylinder chamber of a present Example. It is explanatory sectional drawing which shows the state by which the valve body of the present Example was pushed down. It is explanatory sectional drawing which shows the state by which the valve body of the present Example was pushed up. It is explanatory sectional drawing which shows the constriction part of a present Example.

  Embodiments of the present invention that are considered suitable (how to carry out the invention) will be briefly described with reference to the drawings, illustrating the operation of the present invention.

  In a state immediately before the piston 1 starts moving forward, the piston 1 is located above the cylinder chamber, the upper end portion of the valve body 5 is in contact with the upper surface of the first cylinder chamber 2, and the valve body 5 is pushed downward. The first valve section 7 is closed, the first cylinder chamber 2 and the first communication chamber 6 are closed, the second valve section 11 is opened, and the second communication chamber 9 and the valve body supply path 10 are Communication is established.

  In this state, the pressure oil is pumped through the drive part side supply path 8 and is supplied to the first cylinder chamber 2 through the second cylinder chamber 3 through the second communication chamber 9 and the valve body supply path 10. Is closed in the first cylinder chamber 2 because the first valve portion 7 is closed, the oil pressure in the first cylinder chamber 2 gradually increases, and the upper surface of the piston 1 is pressed by the oil pressure of the pressure oil, and the piston 1 will move downward.

  When the piston 1 moved forward by the hydraulic pressure of the pressure oil supplied into the first cylinder chamber 2 moves downward, the valve body 5 or the inner surface of the third cylinder chamber 4 facing the valve body 5 is provided. The open spring 12 is degenerated, and a spring force is generated in the open spring 12, and this spring force is less than the force pushing down the valve body 5 generated by the pressure oil supplied into the first cylinder chamber 2. When it becomes larger, the valve body 5 is pushed upward, the first valve portion 7 is opened, the first cylinder chamber 2 and the first communication chamber 6 are in communication with each other, and the second valve portion 11 is closed and the second valve portion 11 is closed. The two communication chambers 9 and the valve body supply path 10 are closed.

  When the release spring 12 pushes up the valve body 5, the work is very hard or abnormal resistance occurs due to a malfunction, and an oil pressure higher than expected is generated in the first cylinder chamber 2, and the release spring 12 is degenerated. When the spring force generated by the pressure is weaker than the force pushing down the valve body 5, the release spring 12 cannot push the valve body 5 upward, and the valve state of the valve body 5 cannot be switched. Therefore, the piston 1 does not return.

  In such a case, for example, the open spring 12 is composed of a plurality of springs having different stretching forces, and the spring having the weakest stretching force assuming the oil pressure during normal work and the spring having a stronger stretching force than this weak spring. Since the valve body 5 can be pushed upward by the spring force of the spring having a strong expansion / contraction force, the piston 1 does not move backward without switching the valve state of the valve body 5.

  Further, for example, the valve body 5 pushed up above is positioned below the first valve portion 7 so as not to be pushed down again by the pressure oil and the oil pressure in the first cylinder chamber 2. If the open holding spring 18 is provided so as to push up the valve body 5, the open state of the first valve portion 7 is held by the spring force of the open holding spring 18, and the first valve portion 7 is closed and the first valve portion 7 is closed. The cylinder chamber 2 and the first series passage chamber 6 are closed, and the pressure oil is supplied to the first cylinder chamber 2, thereby preventing the piston 1 from moving forward again.

  Thus, the second valve portion 11 is closed and the second communication chamber 9 and the valve body supply path 10 are closed, whereby the supply of pressure oil to the first cylinder chamber 2 is stopped, and the piston 1 is moved forward. It will end.

  Further, the second valve portion 11 is closed, the second communication chamber 9 and the valve body supply path 10 are closed, and the pressure oil is supplied to the second cylinder chamber 3 instead of being supplied to the first cylinder chamber 2. Since the first valve portion 7 is opened and the first cylinder chamber 2 and the first communication chamber 6 are in communication with each other, the hydraulic pressure of the pressure oil supplied into the second cylinder chamber 3 is reduced to the second cylinder chamber. By pushing up the upper inner surface of the piston 3, the piston 1 starts moving backward.

  Due to the backward movement of the piston 1, the pressure oil in the first cylinder chamber 2 moves to the first series passage chamber 6, and from the first series passage chamber 6 through the third cylinder chamber 4 through the piston oil drain passage 19. Since it moves to the drive part side oil discharge path | route 20, the piston 1 will return smoothly without the oil pressure in the 1st cylinder chamber 2 rising.

  In addition to the first cylinder chamber 2 and the third cylinder chamber 4 positioned above and below, which are partitioned by the piston 1 in this way, a second cylinder chamber 3 is provided by providing a recess in the peripheral surface of the piston 1, and this second cylinder A configuration in which pressure oil is supplied through the chamber 3 and a configuration in which a valve body 5 provided adjacent to the piston 1 and a valve portion that is automatically switched by an opening spring 12 in contact with the valve body 5 are provided are provided. Since the number of parts can be greatly reduced compared to cylinders, for example, by applying the present invention to a hydraulically operated drilling machine, it is possible to manufacture an inexpensive drilling machine that is easy to design with a simple structure and that is small and lightweight. This is an epoch-making double-acting hydraulic cylinder with excellent productivity and practicality.

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

  In this embodiment, as shown in FIGS. 1 to 4, the pressure oil is supplied to the first cylinder chamber 2, and the piston 1 is pushed forward by the oil pressure of the pressure oil, and the valve portion provided in the valve body 5. The supply of pressure oil to the first cylinder chamber 2 is stopped by automatically switching the state of, and instead of supplying pressure oil to the second cylinder chamber 3, the piston 1 is driven by the oil pressure of this pressure oil. This is a double-acting hydraulic cylinder that pushes up and moves backward.

  A specific configuration of this embodiment is shown below.

  In the present embodiment, as shown in FIG. 5, the cylinder chamber is divided into three chambers by the piston head portion 21 of the piston 1 provided in the cylinder chamber, and the first cylinder chamber 2 having the upper surface of the piston head portion 21 as the lower inner surface, A third cylinder chamber 4 having the lower surface of the piston head portion 21 as the upper inner surface is formed, and a recess is provided on the peripheral surface of the piston head portion 21, and this recess is used as the second cylinder chamber 3.

  As shown in FIG. 6, the second cylinder chamber 3 communicates with the drive unit side supply path 8. Even when the piston 1 moves up and down, the second cylinder chamber 3 is always in communication with the drive unit side supply path 8. And a U-shaped recess is provided at a substantially intermediate position in the height direction of the piston head portion 21.

  Further, when the pressure oil is supplied to the second cylinder chamber 3 and an oil pressure is generated by the pressure oil, the area of the upper inner surface of the recess is increased so that the oil pressure causes the piston 1 to be pushed upward. The cylinder chamber has an inner diameter that is longer from the middle position to a larger area than the inner surface of the lower part, and a lower part that is shortened on the lower side. The upper side has a longer diameter and the lower side has a shorter shape.

  Further, the third cylinder chamber 4 is provided with a driving portion side discharge path 20 for discharging the pressure oil downward, and a piston that is in contact with the lower surface of the piston head portion 21 and the lower inner surface of the third cylinder chamber 4. A return spring 13 is provided.

  The piston return spring 13 is used to push up the piston 1 so that the piston 1 does not fall downward due to its own weight when the piston 1 is located above the cylinder chamber and is in an inoperative state. At the same time, the piston 1 is pushed up in an auxiliary manner.

  In addition, a through-hole penetrating the first cylinder chamber 2 and the third cylinder chamber 4 is formed in the piston head portion 21, and the valve body 5 is provided in the through-hole.

  The through hole is provided with a first communication chamber 6 that communicates with the first cylinder chamber 2, and a second communication chamber 9 that is located below the first communication chamber 6 and communicates with the second cylinder chamber 3. ing.

  In addition, the first cylinder chamber 2 and the first series chamber 6 communicating with the valve body 5 are provided in the first valve portion 7 for switching the communication state and the closed state, the second communication chamber 9 and the valve body 5. A second valve portion 11 is provided for switching the valve body supply path 10 between a communication state and a closed state.

  The valve body side supply path 10 is formed up to the upper end portion of the valve body 5. Further, a concave groove is formed in the upper end portion of the valve body 5 to provide a pressure oil supply port 22, and the upper end portion of the valve body 5 is the first end portion. Even in a state of being in contact with the upper inner surface of one cylinder chamber 2, the pressure oil fed from the pressure oil supply port 22 through the valve element side supply path 10 can be supplied into the first cylinder chamber 2. .

  As shown in FIGS. 7 and 8, the first valve portion 7 and the second valve portion 11 are closed when the valve body 5 is pushed downward, and the first valve portion 7 is closed. The first communication chamber 6 is closed, the second valve portion 11 is opened, the second communication chamber 9 and the valve body supply path 10 are in communication, and the valve body 5 is pushed upward. In the state, the first valve portion 7 is opened and the first cylinder chamber 2 and the first communication chamber 6 are in communication with each other, the second valve portion 11 is closed and the second communication chamber 9 and the valve element side supply path 10 are closed. The configuration is in a state.

  In addition, the upper end of the piston 1 is formed with an upper horizontal surface that is slightly lower than the upper surface of the piston 1, and a joining portion 16 that joins the first valve portion 7 in a bowl shape is provided.

  Even when the lower horizontal surface of the first valve portion 7 and the upper horizontal surface of the joint portion 16 are joined, the joint portion is formed between the lower vertical surface of the first valve portion 7 and the side surface of the joint portion 16. A slight gap is formed between them.

  Furthermore, an opening spring 12 that abuts against the lower inner surface of the third cylinder chamber 4 is suspended from the lower end of the valve body 5, and the opening spring 12 is divided into two types, a first opening spring 14 and a second opening spring 15. Consists of springs with different stretching forces.

  The first opening spring 14 is longer than the second opening spring 15 described later, and contacts the lower inner surface of the third cylinder chamber 4 before the second opening spring 15 when the piston 1 moves forward. In this configuration, the valve body 5 is pushed upward by contracting and generating a spring force.

  The second opening spring 15 cannot push up the valve body 5 by the spring force obtained by the contraction of the first opening spring 14, and is formed on the lower inner surface of the third cylinder chamber 4 when the piston 1 further moves forward. The valve body 5 is pushed upward by generating a spring force stronger than the spring force obtained by abutting and retracting and the first opening spring 14 retracting.

  In the present embodiment, the opening spring 12 has a configuration in which a first opening spring 14 and a second opening spring 15 having two different stretching forces are arranged concentrically, but the first opening spring 14 and the second opening spring 15 are A configuration in which the two are connected in series may be used, or two types of springs having different stretching forces may be used, and one type of unequal pitch springs may be used, or three or more types of springs may be used.

  As described above, the present embodiment has a very simple configuration as compared with a complicated structure such as a conventional double-acting hydraulic cylinder, and the number of parts is smaller than the conventional structure. For example, if applied to a hydraulically operated processing machine such as a punching machine, it can be made smaller and lighter than a conventional machine, and can be manufactured at a lower cost. A double acting hydraulic cylinder.

  Next, specific operations of the present embodiment will be described below.

  The state before the operation of this embodiment is a state in which the piston 1 is pushed upward by the piston return spring 13 provided in the third cylinder chamber 4 and positioned at the uppermost position. At this time, the upper end portion of the valve body 5 is Since the valve body 5 itself is in a state of being pressed downward while being in contact with the upper inner surface of the first cylinder chamber 2, the first valve portion 7 is closed, and the first cylinder chamber 2 and the first continuous passage. The chamber 6 is closed, the second valve portion 11 is opened, and the second communication chamber 9 and the valve element side supply path 10 are in communication.

  The pressure oil pumped by the drive of the drive unit into the cylinder chamber in such a state is supplied from the drive unit side supply path 8 to the second communication chamber 9 through the second cylinder chamber 3.

  Since the second communication chamber 9 and the valve body side supply path 10 are in communication with each other, the pressure oil supplied to the second communication chamber 9 is directly passed through the valve body side supply path 10 from the pressure oil supply port 22 to the first cylinder. Oil pressure is generated in the first cylinder chamber 2 by the pressure oil supplied into the chamber 2 and accumulated in the first cylinder chamber 2, and the upper surface of the piston 1 (the lower inner surface of the first cylinder chamber 2) by this oil pressure. Is pushed downward, and the piston 1 starts moving against the spring force of the piston return spring 13 provided in the third cylinder chamber 4.

  When the piston 1 starts moving forward, the upper end portion of the valve body 5 is separated from the upper inner surface of the first cylinder chamber 2, and at this time, the open holding spring 18 provided in the first series passage chamber 6 is connected to the first valve portion 7. Although the force which pushes up the valve body 5 from below acts, this open holding spring 18 uses a spring having a spring force weaker than the oil pressure when the piston 1 starts to move forward. The piston 1 continues to move forward without opening 7.

  When the piston 1 continues to move forward, the first opening spring 14 suspended from the lower end of the valve body 5 comes into contact with the lower inner surface of the third cylinder chamber 4 and begins to degenerate. When the spring force is larger than the force that pushes down the valve body 5 generated by the pressure oil supplied into the first cylinder chamber 2, the valve body 5 is pushed upward, When the valve portion 7 is opened, the second valve portion 11 is closed, and this state is maintained by the open holding spring 18, the first cylinder chamber 2 and the first series passage chamber 6 are in communication with each other. The communication chamber 9 and the valve body side supply path 10 are closed.

  Accordingly, the supply of pressure oil into the first cylinder chamber 2 is stopped, and the oil pressure in the first cylinder chamber 2 is reduced by the communication between the first cylinder chamber 2 and the first communication chamber 6. By doing so, the forward movement of the piston 1 is completed.

  Further, when the piston 1 is in an operating state, for example, the work is made of a very hard material or a soft material causes a problem such as being caught, so that the oil pressure in the first cylinder chamber 2 is normal. When the valve body 5 cannot be pushed upward by the spring force of the first opening spring 14 and the piston 1 moves further forward than the normal forward end position. As a result of this forward movement, the second opening spring 15, which has a stronger expansion / contraction force than the first opening spring 14, comes into contact with the lower inner surface of the third cylinder chamber 4, and the second opening spring 15 is retracted to generate a spring force. The spring force becomes larger than the force that pushes down the valve body 5 generated by the pressure oil supplied into the first cylinder chamber 2, and the forward movement of the piston 1 is completed by pushing the valve body 5 upward. .

  The piston 1 that has finished the forward movement is then switched to the backward movement, but the state immediately before the backward movement in this embodiment is the state in which the valve body 5 is pushed upward, so the first valve portion 7 is opened. The first cylinder chamber 2 and the first communication chamber 6 are in communication with each other, the second valve portion 11 is closed, and the second communication chamber 9 and the valve-body-side supply path 10 are closed.

  The pressure oil pumped by the drive of the drive unit into the cylinder chamber in such a state is supplied from the drive unit side supply path 8 to the second communication chamber 9 via the second cylinder chamber 3. Since the pressure oil cannot be moved beyond the second communication chamber 9, the pressure oil is supplied to the second cylinder chamber 3. The pressure oil supplied to the second cylinder chamber 3 is thus closed. The piston 1 starts moving backward when the hydraulic pressure of the cylinder pushes up the upper inner surface of the second cylinder chamber 3.

  Further, when the piston 1 moves backward, the piston return spring 13 provided in the third cylinder chamber 4 is in contact with the lower surface of the piston head portion 21, and the spring force of the piston return spring 13 is the piston 1. The force that pushes up upwards also acts as an auxiliary.

  When the piston 1 moves backward, the pressure oil in the first cylinder chamber 2 is pushed out from the first cylinder chamber 2 to the first communication chamber 6, and then from the first communication chamber 6 through the in-piston oil discharge passage 19. It is discharged to the drive unit side discharge path 20 through the three cylinder chamber 4.

  When the backward movement further proceeds and the piston 1 approaches the uppermost part in the cylinder chamber, the upper end portion of the valve body 5 comes into contact with the upper inner surface of the first cylinder chamber 2, and a force that pushes down the valve body 5 acts. .

  As the valve body 5 is gradually pushed down, the first valve portion 7 tends to close and the second valve portion 11 gradually opens, so that the oil pressure in the second cylinder chamber 3 gradually decreases. At the same time, the pressure oil is again supplied to the first cylinder chamber 2.

  In this manner, with both the first valve portion 7 and the second valve portion 11 being opened, the upper end portion of the valve body 5 is the upper portion of the first cylinder chamber 2 as the piston 1 gradually moves upward. Since it is in contact with the inner surface, the valve body 5 is gradually pushed downward. As shown in FIG. 9, the joint 16 provided on the lower horizontal surface of the first valve portion 7 and the upper end portion of the piston 1 The opposing gap with the upper surface is narrowed to form the first constricted portion, and the lower vertical surface of the first valve portion 7 and the side surface of the joint portion 16 are also opposed to each other, so that the second constricted portion with an opposing interval narrower than the first constricting portion is formed. Form.

  By the first narrowed portion and the second narrowed portion, the pressure oil path from the first cylinder chamber 2 to the first series passage chamber 6 becomes a constricted state, and the flow of the pressure oil is suppressed, thereby discharging the pressure oil. The speed decreases, the oil pressure in the first cylinder chamber 2 gradually increases, and the first cylinder and the force that pushes up the piston 1 due to the oil pressure in the second cylinder chamber 3 and the spring force of the piston return spring 13 The force that pushes down the piston 1 due to the oil pressure in the chamber 2 is in an equilibrium state, the piston 1 does not move upward or downward, and the return movement of the piston 1 is temporarily terminated.

  In this state, by stopping the driving of the driving unit and stopping the supply of the pressure oil, the supply of the pressure oil to the first cylinder chamber 2 and the second cylinder chamber 3 is stopped, and the first cylinder chamber 2 and the second cylinder chamber 2 are stopped. The hydraulic pressure acting on the cylinder chamber 3 is reduced, and the piston 1 is pushed up to the top of the cylinder chamber by the spring force of the piston return spring 13, the first valve portion 7 is closed, and the second valve portion 11 is opened. The return movement is completed in a state similar to the pre-operation state.

  As described above, the pressure oil pumped by the drive of the drive unit is supplied into the first cylinder chamber 2 so that the piston 1 is moved forward, and automatically by the opening spring unit 12 suspended from the lower end of the valve body 5. Thus, the state of the valve is switched, the supply destination of the pressure oil is changed to the second cylinder chamber 3, and the upper inner surface of the second cylinder chamber 3 is pushed up by the oil pressure to move backward. By providing such a constricted portion, even if the pressure oil continues to be fed, the return movement is completed and the piston 1 can be kept in a stopped state without moving forward again. Double acting hydraulic cylinder.

  Note that the present invention is not limited to this embodiment, and the specific configuration of each component can be designed as appropriate.

DESCRIPTION OF SYMBOLS 1 Piston 2 1st cylinder chamber 3 2nd cylinder chamber 4 3rd cylinder chamber 5 Valve body 6 1st series communication chamber 7 1st valve part 8 Drive part side supply path 9 2nd communication chamber
10 Valve side supply path
11 Second valve
12 Release spring
13 Piston return spring
14 First opening spring
15 Second opening spring
16 joints
17 Stenosis
18 Opening holding spring

Claims (8)

  In a double-acting hydraulic cylinder in which pressurized oil is supplied into a cylinder chamber and the piston is operated up and down, the piston chamber is partitioned by the piston to provide a first cylinder chamber on one side and a second cylinder chamber and a second cylinder on the opposite side. Three cylinder chambers are provided, pressure oil is supplied to the first cylinder chamber, and a valve body is provided on the piston that moves forward by the oil pressure of the pressure oil. The valve body includes the first cylinder chamber and the first cylinder chamber. A first valve portion is provided for switching the first series of chambers, which serve as a path for discharging the hydraulic oil from the cylinder chamber, between a communication state and a closed state, and the drive unit side supply path is configured to pass the second cylinder chamber through the second cylinder chamber. A second communication chamber serving as a path for supplying pressure oil to the first cylinder chamber is provided, and a valve body supply path serving as a path for supplying pressure oil from the second communication chamber to the first cylinder chamber is provided. The valve body supply path and the second communication chamber A second valve portion that switches between a communication state and a closed state is provided, and when the piston moves forward, the valve body is retracted to obtain a spring force, and an opening spring that pushes up the valve body by the spring force is provided by the valve body or the valve body. The first valve portion is opened when the valve body is pushed upward by the opening spring, and the first cylinder chamber and the first continuous chamber are provided. The valve body is configured such that the second valve portion is closed while being in a communication state, and the valve body is pushed upward by the operation of the release spring, and the second valve portion is closed. The supply of the pressure oil to the one cylinder chamber is stopped, the supply destination of the pressure oil is switched to the second cylinder chamber, the pressure oil is supplied to the second cylinder chamber, and the oil pressure of the pressure oil is changed to the second cylinder chamber. By pushing up the upper inner surface of the cylinder chamber Double-acting hydraulic cylinder piston is characterized by backward pushed up.   The first cylinder chamber has an upper surface of the piston as a bottom surface, the third cylinder chamber has a lower surface of the piston as an upper surface, and a piston return spring that contacts the upper surface and a lower inner surface of the third cylinder chamber is provided, The second cylinder chamber is formed with a recess along the circumferential surface of the piston at a position between the first cylinder chamber and the third cylinder chamber. The double-acting hydraulic cylinder according to claim 1, wherein the double-acting hydraulic cylinder is provided.   The said recessed part was formed along the surrounding surface of the said piston, and the area of the upper surface of this recessed part was set to the area larger than the area of a lower surface, The any one of Claims 1, 2 characterized by the above-mentioned. Double acting hydraulic cylinder.   The opening spring is provided with two or more springs having different expansion / contraction forces, and is configured such that when the piston moves forward, a spring having a low expansion / contraction force is first retracted. The double acting according to any one of claims 1 to 3, wherein when the body cannot be pushed up, a spring having a stronger stretching force than the spring having a lower stretching force is in a retracted state. Hydraulic cylinder.   The opening spring is composed of a first opening spring and a second opening spring having different expansion / contraction forces, and the first opening spring is an oil that acts on the upper surface of the piston by obtaining a spring force when the piston moves forward and retracts. The second opening spring has a stretching force stronger than that of the first opening spring, and the first opening spring and the first opening spring have a stretching force that extends when the spring force becomes larger than the pressure. 2. The two opening springs are provided concentrically with the first opening spring connected downward or the length of the first opening spring being longer than the length of the second opening spring. The double-acting hydraulic cylinder of any one of -4.   The piston moves backward, the upper end portion of the valve body comes into contact with the upper inner surface of the first cylinder chamber, and the first valve portion moves downward. A narrowing portion is formed in which the interval between the piston and the joint portion to be joined gradually narrows to narrow the path of the pressure oil, and the pressure oil from the first cylinder chamber to the first communication chamber is formed by the narrowing portion. When the discharge speed of the first cylinder chamber decreases and the oil pressure in the first cylinder chamber increases, the oil pressure in the first cylinder chamber, the oil pressure acting on the upper surface of the second cylinder chamber that moves the piston back, and the The compounding device according to any one of claims 1 to 5, wherein the constriction is set so that the sum of the force and the spring force of the piston return spring is in an equilibrium state and the return movement of the piston is stopped. Dynamic hydraulic cylinder.   The constricted portion is formed such that the piston moves backward and the first valve portion is pushed downward, and the facing distance between the lower horizontal surface of the first valve portion and the upper horizontal surface of the joint portion is narrowed to form the first constricted portion. When the first constricted portion is formed, the lower vertical surface of the first valve portion and the side surface of the joint portion are opposed to each other, and the lower vertical surface of the first valve portion and the joint portion are 7. The stenosis portion having a side surface formed with a second stenosis portion having a narrower facing distance than the first stenosis portion and having a pressure oil path having a constricted shape, is provided. The double-acting hydraulic cylinder as described in item 1.   When the valve body is pushed upward by the release spring, the first valve portion is opened, and the first cylinder chamber and the first communication chamber are in communication with each other. The double-acting hydraulic cylinder according to any one of claims 1 to 7, further comprising an open holding spring for holding a communication state with the first series of chambers.

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