JPH11303811A - Automatic expansion cylinder device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an automatic expansion cylinder device with can reciprocate at a prescribed period by only a hydraulic mechanism. SOLUTION: A hydraulic selector valve 14 for opening/closing the communication of right/left oil chambers 12, 13 is provided in a piston 11. A first port 17 for selectively communicating with one side oil chamber 12 and a second port 18 for selectively communicating with the other oil chamber 13 are provided on the spool 15 of the selector valve 14 and both first/second ports 17, 18 are intercepted at a spool neutral position and when they are displaced from their positions to either way, they are communicated with either oil chamber 12 or 13 mutuary and contrarily and the first port 17 and always communicated with the oil chamber 13. The second port 18 always communicated with the port of a low pressure side and the oil chamber 12 is connected to a pump side, while the pressure receive area of one side oil chamber 12 side of the spool 15 is set to smaller than that of the other oil chamber 13 side.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic cylinder device that automatically extends and retracts.

[0002]

2. Description of the Related Art Conventionally, a switching valve as shown in FIG. 6, for example, is used to extend and retract a hydraulic cylinder or the like at a constant cycle.

A switching valve 2 for supplying and discharging hydraulic oil from a hydraulic source 1 is provided. When a high pressure is selectively supplied to the oil chambers 4A and 4B of the cylinder 3 by the switching valve 2, the switching valve The piston 5 moves. The switching valve 2 is switched at a constant cycle by a signal (not shown), for example, and the one oil chamber 4
The operation of introducing high pressure into A and releasing the other oil chamber 4B to the tank side is repeated and continued. This allows the cylinder 3
Repeats the expansion and contraction operation at a constant cycle.

[0004]

However, in such an apparatus, the following problems cannot be avoided.

[0005] When the cylinder is reciprocated with full stroke, the piston collides with the cylinder end wall at the stroke end and generates an impact.

As the reciprocating frequency of the cylinder is increased,
The cylinder amplitude decreases, and in this case, the center of the amplitude gradually shifts due to oil leakage or the like, and eventually reaches the stroke end and cannot be displaced toward the extension or contraction side.

An object of the present invention is to solve such a problem by providing an automatic telescopic cylinder device capable of reciprocating at a certain cycle only by a hydraulic mechanism.

[0008]

According to a first aspect of the present invention, there is provided a cylinder device in which a piston is slidably housed in a cylinder, and a rod-side oil chamber and a cylinder-side oil chamber are respectively defined on both sides thereof. A hydraulic switching valve for opening and closing the communication between the left and right oil chambers is provided on the piston, and the switching valve is provided with a spool that slides in parallel with the piston, and both ends of the spool are projected from both surfaces of the piston so as to be able to abut the cylinder inner wall. Along with
The spool has a first port selectively communicating with one of the rod-side oil chambers, a second port selectively communicating with the other cylinder-side oil chamber, and the first port in the spool neutral position. Is shut off from one oil chamber, the second port is also shut off from the other oil chamber, and when displaced from either position, the first and second ports are reciprocally opposed to each other. The first and second port positions are set so as to communicate with the oil chamber. The first port always communicates with the other oil chamber, and the second port constantly communicates with the low-pressure side port provided in the piston. The low pressure side port is connected to an external tank side through a passage inside the piston, and the rod side oil chamber is connected to the pump side, while the pressure receiving area of one rod side oil chamber of the spool is connected. Is the other cylinder side oil chamber Characterized in that it is smaller than the pressure receiving area.

According to a second aspect of the present invention, in the first aspect of the present invention, in the switching valve, the stopper penetrates coaxially and slidably inside the spool, and the end of the cylinder side oil chamber of the stopper contacts the spool. Sometimes, an intermediate chamber is formed between the two, and the intermediate chamber communicates with the first port and communicates with the cylinder-side oil chamber via a fixed throttle provided in a stopper.

In a third aspect based on the first or second aspect, the low pressure side port provided in the piston communicates with an internal chamber inside the piston, and the cylinder provided in the cylinder slides into the piston internal chamber. The cylinder is freely movably inserted, and the cylinder is connected to an external tank via a passage provided in the cylinder.

[0011]

In the first invention, when high pressure is introduced into one rod-side oil chamber, the opposite cylinder-side oil chamber is released to low pressure, so that the spool of the switching valve is pushed. The first port is closed and the piston moves toward the other oil chamber. Near the moving end, the spool comes into contact with the inner wall of the cylinder and stops, but the piston moves as it is, and the spool switches beyond the neutral position. As a result, the first port is opened, and the second port is closed to shut off the other pressure chamber from the low pressure side. Thereby, the high pressure in one pressure chamber is guided to the other pressure chamber via the inside of the spool. Because the spool has a large pressure receiving area on the other pressure chamber side, it is pushed by one pressure chamber side, and the introduction of high pressure to the other pressure chamber is maintained. Then, due to the difference in the pressure receiving area, it moves toward the opposite side.

In the vicinity of the moving end of the piston, the opposite end of the spool comes into contact with the inner wall of the cylinder and stops, and the movement of the piston causes the spool to switch over from the neutral position to the opposite side. This causes the piston to move again in the opposite direction. In this way, the reciprocating motion is continuously repeated.

In this case, when the piston moves,
After the spool collides with the cylinder end wall, the opening area of the first or second port for discharging the hydraulic oil from the oil chamber is gradually narrowed, so that the moving speed of the piston decreases accordingly. Even without providing a special cushion mechanism, the piston does not collide with the cylinder end wall, and no impact is generated when the direction of the piston is reversed. The moving speed of the piston is proportional to the flow rate of the high-pressure hydraulic oil to be introduced, and the speed increases as the flow rate increases.However, since the piston is always inverted at the same position, the stroke amount is independent of the flow rate. Is constant, and its amplitude center is also constant, so that the amplitude center does not shift.

In the second aspect of the invention, when the piston reaches the limit of the movement of the cylinder side oil chamber, the pressure oil from the rod side oil chamber flows from the intermediate chamber between the stopper and the spool via the fixed throttle, As a result, a pressure difference is sequentially formed between the intermediate chamber and the cylinder-side oil chamber, and the switching of the switching valve can be smoothly performed.

According to the third aspect of the present invention, even if the piston reciprocates, the low pressure side is always communicated from the piston to the cylinder, so that a smooth operation can be guaranteed.

[0016]

FIG. 1 shows an embodiment of the present invention.

In the drawing, reference numeral 10 denotes a cylinder, and 11 denotes a single-rod type piston slidably housed in the cylinder 10.
Thus, an oil chamber 13 on the cylinder side is defined.

A spool type hydraulic switching valve 14 is provided inside the piston 11, and the switching valve 14
Stepped sliding hole 1 whose inner diameter changes in the middle provided in parallel with
6, a stepped spool 15 is slidably disposed, and a stopper 24 penetrates freely through the axis of the spool 15.
And 23 project.

The spool 15 has a sectional area A on the oil chamber 13 side.
1 is larger than the sectional area A2 on the oil chamber 12 side.

Annular ports 17 and 18 having a predetermined width are formed around the spool 15 at intervals. One of the annular ports (first port) 17 is the spool 1
Oil chamber 13 on the opposite side via a through hole 19 provided at the center of
Always communicate with This annular port 17 is provided with a spool 15
When the high pressure of the oil chamber 12 acts on the right end of the spool 15 through the through hole 22A, the communication with the oil chamber 12 is interrupted when the left side of the spool 15 is displaced in the drawing until the left end of the spool 15 contacts the stopper 24. Conversely, when the flange 15A at the left end of the spool 15 on the oil chamber 13 side is displaced rightward until it comes into contact with the left end face of the piston, the spool 15 communicates with the oil chamber 12.

On the other hand, the annular port (second port) 18 on the oil chamber 13 side is always in communication with an internal oil chamber 20 formed inside the piston 11 via a port 21. The annular port 18 communicates with the oil chamber 13 when the spool 15 is displaced to the left similarly to the above, but the communication with the oil chamber 13 is cut off when the spool 15 is displaced to the right.

However, when the spool 15 comes to the neutral position (the state shown in FIG. 2), both of the annular ports 17 and 18 are shut off with respect to the oil chambers 12 and 13, and when the spool 15 is slightly displaced from this neutral position. , One of which always communicates with one of the oil chambers.

When the left end of the spool 15 in the figure comes into close contact with the stopper 24, an intermediate chamber 25 formed therebetween communicates with the oil chamber 13, so that a fixed orifice (throttle) is provided at the enlarged end 23 of the stopper 24. 24A are formed. The intermediate chamber 25 is always in communication with the through hole 19.

The internal oil chamber 20 has a cylindrical portion 26 projecting coaxially with the piston 11 from the end wall 10A of the cylinder 10.
The cylindrical portion 26 is provided in the oil chamber 2 of the piston 11.
0 is slidably inserted in an oil-tight manner. The cylindrical portion 26 is connected to a discharge passage 28 formed in a part of the cylinder 10, and the internal oil chamber 20 always communicates with the tank 27 via the discharge passage 28. On the other hand, the oil chamber 12 is connected to the discharge side of a pump 30 via a pump port 29, and a high pressure is introduced into the oil chamber 13.

The operation will be described below with reference to FIGS. 1 and 2 to 4.

When a high pressure is introduced into the oil chamber 12 on the right side of the piston 11 from the state shown in FIG. 1, the spool 15 of the switching valve 14 is pushed, and the annular port 17 closes the communication with the oil chamber 12. At this time, the left oil chamber 13 communicates with the internal oil chamber 20 via the annular port 18 and has a low pressure, so that the piston 11 starts moving leftward in the drawing.

During the movement of the piston 11, the spool 15 of the switching valve 14 is pushed by the pressure of the oil chamber 12 and is in the state shown in the figure, and the annular port 17 and the oil chamber 12 are shut off.

When the piston 11 moves to the vicinity of the limit to the left, the stopper 24 hits the cylinder end wall and is pushed back to the right together with the spool 15 as shown in FIG. During this process, the annular port 18 is closed, and when passing through the neutral position of the switching valve 14, the annular port 17 is opened.

Then, the pressure oil in the oil chamber 12 flows into the intermediate chamber 25, and the pressure in the intermediate chamber 25 increases. When the pressure rises to half the pressure of the oil chamber 12, the pressures at both ends of the spool 15 become equal. However, since the oil chamber 13 communicates with the intermediate chamber 25 via the fixed orifice 24A,
The pressure in the intermediate chamber 25 is higher. Depending on the pressure receiving area of the oil chambers 12 and 13, if the pressure receiving area A1 of the oil chamber 13 is twice or more the pressure receiving area A2 of the oil chamber 12, the pressure difference between the oil chambers 12 and 13 causes the piston 11 to move to the left. The piston 11 moves to the left while the force acting toward it is large.

Thus, the annular port 17 of the switching valve 14
Open further, the pressure of the intermediate chamber 25 further increases, and from the relationship between the left and right pressure receiving areas of the spool 15, when the pressure of the intermediate chamber 25 increases to half or more of the pressure of the oil chamber 12,
The spool 15 is pushed rightward until it comes into contact with the piston 11 (see FIG. 3).

Therefore, the annular port 1 is connected to the oil chamber 13.
8 is completely closed and the annular port 17 is greatly opened to the oil chamber 12 side, so that the oil chambers 12 and 13 have the same pressure. Since the pressure receiving area of the piston 11 on the oil chamber 13 side is large, the piston 11 starts to move in the opposite direction.

Then, when the piston 11 moves rightward to the vicinity of the limit, the right end of the stopper 24 hits the cylinder end wall.
4, the spool 15 moves in the opposite direction, and the switching valve 14
The annular port 17 is closed as shown in FIG. As a result, the pressure in the oil chamber 13 decreases, and the pressure in the oil chamber 13 decreases.
When the pressure is reduced to half of the pressure, the forces acting on both ends of the switching valve 14 are balanced. However, since the pressure receiving area ratio of the piston 11 exceeds twice, the piston 11 still continues to move to the right.

When the pressure in the oil chamber 13 falls below half of the pressure in the oil chamber 12 as the switching valve 14 passes the neutral position and the annular port 18 opens, the switching valve 14 moves as shown in FIG. Switch to the left side.

Then, returning to the initial state, the oil chamber 13 becomes almost the same pressure as the tank pressure, and the piston 11 starts moving leftward due to the pressure of the oil chamber 12.

In this manner, the above operation is repeated thereafter, and the piston 11 reciprocates at a predetermined cycle at a speed corresponding to the supplied hydraulic oil flow rate.

In this case, for example, the piston 11
Moves to the left, the switching valve 15 in FIG.
Moves at a high speed up to a stroke L1 at which the piston 11 collides with the cylinder end wall. Thereafter, the opening area of the annular port 18 for discharging the hydraulic oil from the oil chamber 13 is gradually reduced to the stroke L2. The speed of the oil chamber 13 reverses from a low pressure to a high pressure until the end of the stroke, and the piston 11 is connected to the cylinder end wall without providing a special cushion mechanism. There is no collision, and no impact occurs when the direction of the piston 11 is reversed. The same occurs when the piston 11 moves to the right, and the piston 11 reverses direction while decelerating as it approaches the stroke end.

The moving speed of the piston 11 is proportional to the flow rate of the hydraulic oil introduced from the pump port 29, and the speed increases as the flow rate increases. However, the reversal of the moving direction of the piston 11 is always performed at the same position. Therefore, the stroke amount is constant irrespective of the magnitude of the flow rate, and its amplitude center is also constant and does not shift.

In this case, the strokes L1 and L1
By setting 2, the stroke of the reciprocating piston can be freely adjusted.

Next, a second embodiment will be described with reference to FIG.

This is a cylindrical part 26A integrated with the piston 11.
Which is slidably inserted into an internal chamber 20A formed inside the end wall of the cylinder 10.

By machining the piston 11 and the cylindrical portion 26A integrally, the accuracy of the concentricity is improved and the cylinder 1
By machining the inner chamber 20A concentrically on the 0 side,
6A and the inner chamber 20A can be smoothly slid. The operation is not different from that of the first embodiment.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a cross-sectional view illustrating an operating state.

FIG. 3 is a cross-sectional view illustrating an operating state.

FIG. 4 is a cross-sectional view illustrating an operating state.

FIG. 5 is a cross-sectional view showing another embodiment.

FIG. 6 is an explanatory diagram of a conventional example.

[Explanation of symbols]

 Reference Signs List 10 cylinder 11 piston 12 oil chamber 13 oil chamber 14 switching valve 15 spool 17 annular port (first port) 18 annular port (second port) 19 through hole 20 internal chamber 24 stopper 24B fixed orifice 25 intermediate chamber

Claims (3)

[Claims] A piston is slidably housed in a cylinder,
In a cylinder device in which a rod-side oil chamber and a cylinder-side oil chamber are respectively defined on both sides thereof, a hydraulic switching valve for opening and closing communication between the left and right oil chambers is provided on the piston, and the switching valve slides in parallel with the piston. The both ends of this spool are protruded from both surfaces of the piston so as to be able to contact the inner wall of the cylinder. The spool has a first port selectively communicating with one rod-side oil chamber, and a second port on the other cylinder side. A second port selectively communicating with the oil chamber, and when the first port is disconnected from the one oil chamber in the spool neutral position, the second port is also disconnected from the other oil chamber; When displaced to either of the positions, the first and second ports are set with the first and second port positions so that the first and second ports communicate with one of the oil chambers in a manner contrary to each other. The other The second port is always in communication with a low pressure side port provided in the piston, and the low pressure side port is connected to an external tank through a passage inside the piston. The one rod-side oil chamber is connected to the pump side, and the pressure receiving area of one rod-side oil chamber of the spool is set to be smaller than the pressure receiving area of the other cylinder-side oil chamber. Cylinder device. 2. The switching valve has a stopper coaxially and slidably penetrating inside the spool, and an intermediate chamber is formed between the end of the cylinder side oil chamber of the stopper and the piston when the piston comes into contact with the stopper. 2. The automatic telescopic cylinder device according to claim 1, wherein the intermediate chamber communicates with the first port and communicates with a cylinder-side oil chamber via a fixed throttle provided in a stopper. 3. The low pressure side port provided in the piston,
The cylinder part provided in the cylinder is slidably inserted into the piston internal chamber in communication with the internal chamber inside the piston, and the cylindrical part is connected to an external tank through a passage provided in the cylinder. 6. The automatic telescopic cylinder device according to claim 1.