JPH02266105A - Hydraulic cylinder device - Google Patents

Abstract

PURPOSE:To perform automatic switching between a differential circuit and a normal circuit according to load condition without using an electric control circuit by disposing a back pressure generating valve between a smaller cylinder chamber and a fluid discharge port, and disposing a switching valve, in a position, for making or breaking communication between smaller and larger cylinder chambers. CONSTITUTION:The inside of a cylinder tube 11 is divided with a piston 14 into a larger and a smaller cylinder chambers 51, 52. A back pressure generating valve 31 is disposed between a fluid discharge port 21 and the smaller cylinder chamber 52. Disposing a switching valve 33 in a piston 14, the larger and smaller cylinder chamber 51, 52 are communicated to each other when pressurized fluid is supplied to the larger cylinder chamber 51 at a pressure lower than a specified value, and the communication between the is shut off when a pressure higher than the specified value is produced in the smaller cylinder chamber 52. Switching between a differential circuit and a normal circuit is performed automatically without using an electric control circuit.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a fluid pressure cylinder device that can automatically configure a differential circuit depending on the load.

[Conventional technology and its problems]

2. Description of the Related Art Conventionally, a differential circuit has been used as one method of using double-acting hydraulic cylinders.

In the differential circuit, the cylinder chambers on both sides of the piston are communicated with each other, and pressure oil flows from the cylinder chamber with a smaller pressure-receiving area to the larger cylinder chamber, thereby increasing the moving speed of the piston. Therefore, by switching between a normal circuit and a differential circuit, for example, when there is no load, the differential circuit performs fast forwarding, and when the load increases, the normal circuit presses the load with high output, thereby making the work easier. Used to increase efficiency. In other words, a differential circuit is rarely used only as a differential circuit, and is often used in combination with a normal circuit.

In order to use a differential circuit, conventional hydraulic cylinders use an electromagnetic switching valve to configure the differential circuit, and are also equipped with a limit switch to detect the switching position between the differential circuit and the normal circuit. , the piston rod of the hydraulic cylinder was configured to switch the above-mentioned electromagnetic switching valve when its limit switch was actuated.

Therefore, it is necessary to install the limit switch in an appropriate position, and an electric control circuit is required to switch the electromagnetic switching valve according to the signal from the limit switch, resulting in a complex configuration and high cost. Ta.

In addition, since the differential circuit is switched by a limit switch, it is not necessarily switched in accordance with the load state; for example, even if there is no load before a load is applied, the circuit is switched to a normal circuit. There is a problem in that the time between switching to a normal circuit and applying a load is slow and wastes time, resulting in a correspondingly longer cycle time.

In view of the above-mentioned problems, the present invention provides a fluid system in which a differential circuit and a normal circuit are automatically switched according to the load condition without using an electric control circuit, and there is no wasted operation time. The purpose is to provide a pressure cylinder device.

[Means to solve the problem]

In order to solve the above-mentioned problem, the invention of claim 1 provides a cylinder tube, a cylinder cover that closes both ends of the cylinder tube, a piston that slides inside the cylinder tube, and a cylinder cover that is connected to the piston. and a piston rod passing through at least one of In the cylinder device, a back pressure generation valve is provided between the small cylinder chamber and the fluid discharge port for generating a back pressure of a certain level or more in the small cylinder chamber, and the piston is provided with a back pressure generating valve in the large cylinder chamber. A switching valve is provided for communicating or blocking communication between the large cylinder chamber and the small cylinder chamber, and the switching valve is in a communicating state when pressurized fluid is supplied to the large cylinder chamber and the pressure thereof is below a certain level. The small cylinder chamber is configured to be in a shut-off state when a pressure above a certain level is generated in the small cylinder chamber.

In addition to the above configuration, the invention of claim 2 provides that the switching valve includes a valve chamber provided in the piston and having a valve hole communicating with the large cylinder chamber and the small cylinder chamber, respectively, and an inner portion of the valve chamber. The valve body is configured to have a valve body that can move and close each of the valve holes with a pressure above a certain level.

In addition to the above-mentioned structure, the invention of claim 3 includes:
A spring member is provided that biases the valve body in a direction to close the valve hole on the side of the small cylinder chamber, and in a free state, the spring member protrudes and presses the surface of the valve body on the side of the small cylinder chamber. A pylon spool is provided that contracts when the pressure of the cylinder reaches a certain level or more, thereby allowing the valve body to close the valve hole on the small cylinder chamber side.

[For production]

When pressure fluid is being supplied to the large cylinder chamber, if the pressure within the large cylinder chamber is below a certain level, the switching valve is placed in a communicating state to form a differential circuit.

The back pressure generation valve generates back pressure in the small cylinder chamber, and when the back pressure exceeds a certain level, the switching valve switches to cut off the large cylinder chamber and the small cylinder chamber, and the differential circuit is released. It becomes a normal circuit.

By moving within the valve chamber, the valve body of the switching valve operates to switch between a blocking state in which the valve holes are closed and a communicating state in which none of the valve holes are closed.

The spring member constantly biases the valve body in the direction of closing the valve hole on the small cylinder chamber side.

The pilot spool makes it possible to configure a differential circuit by pressing the valve body in a free state, and also contracts when the pressure in the small cylinder chamber exceeds a certain level, thereby causing the valve body to press against the valve body in the small cylinder chamber. It is possible to close the hole and put it in a blocked state.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional front view of a fluid pressure cylinder device 1 according to the present invention, and FIG. 2 is a hydraulic circuit diagram of the fluid pressure cylinder device 1.

In these figures, the fluid pressure cylinder device 1 includes a cylinder tube 11, cylinder covers 12 and 13 that close both ends of the cylinder tube 11, a piston 14 that slides inside the cylinder tube 11, and one cylinder cover that is connected to the piston 14. It is composed of a piston rod 15 passing through the piston rod 12 and the like.

A large cylinder chamber 51 in which the piston 14 has a larger pressure receiving area and a small cylinder chamber 52 in which the piston has a smaller pressure receiving area are formed in the cylinder tube 11. The cylinder cover 12.13 is provided with ports 21.22 for supplying and discharging pressure oil.

The cylinder cover 12 includes a small cylinder chamber 52 and a port 2.
1, a back pressure generation valve 31 for generating back pressure PH of a certain level or more in the small cylinder chamber 52, and port 2.
A check valve 32 is provided which allows free flow from the cylinder chamber 1 to the small cylinder chamber 52. The piston 14 is provided with a switching valve 33 for communicating or blocking communication between the large cylinder chamber 51 and the small cylinder chamber 52.

The back pressure generating valve 31 consists of a spherical valve body 63 pressed against a valve seat 64 by a compression spring 62, and an adjustment screw 61 that adjusts the compression force of the compression spring 62.
1, the magnitude of the back pressure PH generated in the small cylinder chamber 52 is adjusted. In other words, the back pressure generating valve 31 of this embodiment is a type of pressure regulating valve or relief valve that utilizes the cranking pressure of the check valve.

The check valve 32 is connected to a spherical valve body 6 by a compression spring 69.
This is a known structure in which the valve seat 67 is pressed against the valve seat 67.

The switching valve 33 has a valve seat 1-71.72 and a valve seat 72 fitted into a hole 14a provided in the piston 14.
A cap screw 73 that fixes the valve to the piston 14, a valve spool 74 that can slide within the valve seat 71, a compression spring 75 that biases the valve spool 74 to the right in FIG. 1 (in the direction of arrow M1), and is continuous with the hole 14a. The pilot spool 76 is slidably provided in the hole 14b, and the pilot spool 76 is moved in the direction of the valve spool 74 (arrow M
It is made up of a compression spring 77 that presses in two directions.

The valve seats 71 and 72 are provided with valve holes 81 and 82 that communicate with the large cylinder chamber 51 or the small cylinder chamber 52, and a valve chamber 83 is formed inside the valve seat 71.

The valve spool 74 is provided with a communication hole 84 so that it can move freely within the valve chamber 83, and when the valve spool 74 moves within the valve chamber 83 to the left and right stroke ends, the valve spool 74 moves freely within the valve chamber 83. Close holes 81,82.

In other words, when the valve spool 74 is pressed against the valve seat 71, it functions as a check valve that allows free flow from the small cylinder chamber 52 to the large cylinder chamber 51.
When the valve spool 74 is pressed against the valve seat 72, it functions as a check valve that allows free flow from the large cylinder chamber 51 to the small cylinder chamber 52, and when the valve spool 74 is in the intermediate position of the valve chamber 83, It functions as a communication path that communicates between the large cylinder chamber 51 and the small cylinder chamber 52.

The pylon toss spool 76 has a shaft portion 76a that penetrates inside the valve hole 82 and presses the valve spool 74 toward the valve seat 72, and in a free state where the pressure is zero, it is stronger than the compression spring 75. The valve hole 81 is closed by being pushed by the compression spring 77. The length of the shaft portion 76a is
The length is such that the valve spool 74 can close the valve hole 82 when the pilot spool 76 is in contact with the bottom of the hole 14b, that is, at the stroke end in the direction of arrow M1.

Note that 85 connects the inside of the valve hole 82 and the hole 14b to the small cylinder chamber 5.
A communication hole 86 is a communication hole for communicating the chamber in which the compression spring 77 is installed in the hole 14b with the outside air.

Next, the operation of the fluid pressure cylinder device 1 configured as described above will be explained.

Note that the pressure in the large cylinder chamber 51 is Pl, and the pressure in the small cylinder chamber 5 is
Let the pressure of 2 be P2.

The back pressure PH generated by the back pressure generating valve 31 is the pressure (
(No-load working pressure)
Here, adjust screw 6 to make it 30 Kg/Cm2.
1 is adjusted.

The set pressure of the compression spring 77 is such that the valve hole 82 is pressed against the halve spool 74 by a pressure higher than the back pressure PH caused by the back pressure generating valve 31.
In order to move the pilot spool 76 in the direction of arrow M1 so that it can be closed by
g/Cm2 or more.

The compression spring 75 is set to have a force of 0.5 kg here since it is sufficient to press the valve spool 74 in the direction of arrow M1 by overcoming frictional resistance.

When the boats 21, 22 are not supplied with pressure oil, that is, in a free state, they are in the state shown in FIGS. 1 and 2.

In this state, if pressure oil is supplied from the boat 22,
Pressure oil flows into the large cylinder chamber 51. In addition, boat 2]
is connected to the oil tank.

When pressure oil flows into the large cylinder chamber 51, the piston 14 moves in the direction of arrow M1 under no load. At this time,
The pressure P1 in the large cylinder chamber 51 becomes the no-load operating pressure,
For example, it is about 10KH/Cm2. Therefore, the valve spool 74 is pushed in the direction of arrow M1 to open the valve hole 81, and also contacts the tip of the shaft portion 76a to open the valve hole 81.
is also open. In other words, the valve spool 74 and the valve chamber 8
3, and the switching valve 33 functions as a communication path. Therefore, the large cylinder chamber 51 and the small cylinder chamber 52
It is in communication with.

As a result, the fluid pressure cylinder device 1 is operated by the differential circuit, and as the piston 14 moves in the direction of arrow M1, the pressure oil in the small cylinder chamber 52 flows into the large cylinder chamber 51 through the switching valve 33. .

When the piston rod 15 comes into contact with the workpiece W, the pressure P1
．． P2 rises together, and the pressure causes the pilot spool 76 to move to the stroke end in the direction of arrow M1 against the compression spring 77, and the valve spool 74 moves against the compression spring 75.
to close the valve hole 82.

As a result, the connection between the large cylinder chamber 51 and the small cylinder chamber 52 is cut off, and the differential circuit disappears, resulting in a normal circuit.

The pressure P1 in the large cylinder chamber 51 is a pressure sufficient to overcome the load caused by the workpiece W on the screw 14, for example, 30 Kg/cm" or more within the maximum pressure range of the hydraulic source,
It rises to several hundred Kg/Crr+2.

The pressure P2 in the small cylinder chamber 52 becomes equal to the back pressure PH1, that is, 30 Kg/Cm2, generated by the back pressure generating valve 31, and this pressure maintains the state of the stroke end position of the pilot spool 76.

In this state, the piston 14 continues to move in the direction of arrow M1.

When the movement (pressing) of the workpiece W is completed and the supply of pressure oil from the boat 22 is stopped, the pressure PI in the large cylinder chamber 5I decreases, and the valve spool 74 moves in the direction of arrow M2 due to the residual pressure P2. .

As a result, the switching valve 33 becomes in a communicating state, the pressure P2 in the small cylinder chamber 52 also decreases, and soon the pressures PL and P2
becomes zero, and the valve spool 74 enters an initial state in which it closes the valve hole 81.

Next, when pressure oil is supplied from the boat 21 and the boat 22 is connected to an oil tank, the pressure oil flows into the small cylinder chamber 52 through the check valve 32 and moves the piston 14 in the direction of arrow M2. At this time, the valve spool 74 is pushed in the direction of arrow M2 by the pressure P2 of the small cylinder chamber 52, and the switching valve 33 maintains the closed state.

According to the embodiment described above, when pressure oil is supplied from the boat 22, when the piston rod 5 is not in contact with the workpiece W and there is no load, the switching valve 33 is brought into communication and automatically switched to the differential circuit. , piston 14 by a differential circuit
moves at high speed.

When the piston rod 15 comes into contact with the workpiece W and a load is applied, the switching valve 33 is cut off, the differential circuit is automatically released and becomes a normal circuit, and the piston 14 moves at low speed and high output.

Therefore, there is no waste in the operation of the piston 14, and its cycle time is shortened compared to the conventional method.

Further, the fluid pressure cylinder device 1 has a built-in switching valve 33 that constitutes a differential circuit, and since it is only necessary to switch the supply and discharge of pressure oil to the fluid pressure cylinder device 1, the differential circuit Hydraulic piping, electrical wiring, and electrical control circuits for configuring the differential circuit and switching between the differential circuit and the normal circuit are not required. Therefore, it is easy to use without requiring complicated work, and is low cost.

In the embodiments described above, the valve spool 74 may be spherical. The back pressure generation valve 31 and the switching valve 33 can have structures, dimensions, and shapes other than those described above. Back pressure generation valve 31, compression spring Z, 75, compression spring 7
7 can be set to various states other than those described above depending on the load state, the dimensions of the fluid pressure cylinder device 1, the state of each part, etc. In addition, the fluid pressure cylinder device l
The structure of can be of various other types.

〔Effect of the invention〕

According to the present invention, there is provided a fluid pressure cylinder device in which a differential circuit and a normal circuit are automatically switched according to the load condition without using an electric control circuit, and there is no wasted operation time. can do.

[Brief explanation of drawings]

FIG. 1 is a sectional front view of a fluid pressure cylinder device according to the present invention, and FIG. 2 is a hydraulic circuit diagram of the fluid pressure cylinder device. DESCRIPTION OF SYMBOLS 1... Fluid pressure cylinder device, 1]... Cylinder cover, 12.13... Cylinder cover, 14... Piston, 15... Piston rod, 21... Bow 1
- (fluid discharge port), 31... back pressure generation valve, 33...
Switching valve, 51... Large cylinder chamber, 52... Small cylinder chamber, 74... Valve spool (valve body), 75.
... Compression C2 (spring member), 76... Pilot spool, 81 82... Valve hole, 83... Valve chamber.

Claims (3)

[Claims] (1) A cylinder tube, a cylinder cover that closes both ends of the cylinder tube, a piston that slides within the cylinder tube, and a piston rod that is connected to the piston and passes through at least one of the cylinder covers. A fluid pressure cylinder device in which a large cylinder chamber in which a piston has a larger pressure receiving area and a small cylinder chamber in which a piston has a smaller pressure receiving area are formed in a cylinder tube, the small cylinder chamber and a fluid discharge port. A back pressure generation valve is provided between the small cylinder chamber and the back pressure generating valve for generating a back pressure of a certain level or more in the small cylinder chamber, and the piston is provided with a valve for communicating between the large cylinder chamber and the small cylinder chamber, or A switching valve for shutting off is provided, and the switching valve is in communication when pressurized fluid is supplied to the large cylinder chamber and the pressure is below a certain level, and a pressure above a certain level is generated in the small cylinder chamber. A fluid pressure cylinder device characterized in that it is configured to be in a cutoff state when (2) The switching valve has a valve chamber provided in the piston and having a valve hole that communicates with the large cylinder chamber and the small cylinder chamber, respectively; A fluid pressure cylinder device comprising a valve body capable of closing the valve hole. (3) The valve chamber is provided with a spring member that biases the valve body in the direction of closing the valve hole on the side of the small cylinder chamber, and in a free state, the spring member protrudes and closes the valve hole on the side of the small cylinder chamber of the valve body. A pilot spool is provided which presses the surface and contracts when the pressure in the small cylinder chamber exceeds a certain level, thereby allowing the valve body to close the valve hole on the small cylinder chamber side. Characteristic fluid pressure cylinder device.