JP2002213410A - Fluid pressure cylinder with locking device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fluid pressure cylinder with a locking device capable of locking a piston, even when the pressure is sealed in the fluid pressure cylinder in emergency stop or the like, and surely unlocking the piston, when the working fluid is fed to a port at a side with a locking mechanism for unlocking the piston. SOLUTION: In this fluid pressure cylinder with the locking device, where a locking cylinder 15 in which a lock piston 16 is inserted, is connected to a head side or a rod side of a cylinder tube 10 in which the piston 6 is inserted and fitted, a pressure chamber 11 formed between the piston 6 and the lock piston 16 is made to communicate with a cylinder port 3a, and the pressure chamber 11 and an atmospheric pressure chamber 17 are cut off in airtight manner by the lock piston 16, a mechanism for communicating the pressure chamber 11 to the atmospheric pressure chamber 17, when the piston 6 approaches a stroke end at the head side or the rod side, is mounted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic cylinder with a lock device.

[0002]

2. Description of the Related Art Conventionally, a hydraulic cylinder with a lock device for locking a piston at a stroke end of the piston is already known without particular examples. FIGS. 5 to 7 show the structure of the conventional hydraulic cylinder with a lock device and the operation principle thereof.

[0003] The conventional hydraulic cylinder 5 with a lock device.
5, the head cover 5 is inserted into a cylinder tube 51 in which a piston 52 is slidably inserted in the axial direction as shown in FIG.
5 and the lock piston 5 is provided in the head cover 55.
6 is provided with a locking cylinder hole 57 which is slidably inserted in a direction perpendicular to the axis of the cylinder tube 51, and a pressure chamber 61 formed between the piston 52 and the lock piston 56 is communicated with a cylinder port 63. , The piston 5
A sleeve 54 forming a cushion ring is fixed to the tip of the piston rod 53 to which the piston 2 is fixed.
A taper portion 54a and a groove 54b into which the tip 56a of the lock piston 56 can be inserted are provided at the tip of the lock piston 56, and the lock piston 56 is urged toward the piston rod 53 by a lock spring 58. In FIG. 5, 66 is a cap serving as a spring seat for the lock spring 58, and 67 is a cushion ring functioning on the rod cover side.

In the hydraulic cylinder with a lock device 50, when the piston rod 53 approaches the stroke end while discharging the air in the head side pressure chamber 61 from the cylinder port 63, as shown in FIG. Of the lock piston 56
a, and the tapered portion 54a
Push up. When the piston rod 53 further approaches the stroke end, the lock piston 56 is further pushed up against the urging force of the lock spring 58, and the tip 56a of the lock piston 56 is moved to the groove 54b of the sleeve 54.
6, the tip 56a of the lock piston 56 enters the groove 54b of the sleeve 54, and the piston rod 53 is locked by the lock piston 56, as shown in FIG.

When the pressure fluid is supplied from the cylinder port 63 to the pressure chamber 61 in order to drive the piston rod 53 in the reverse direction from the locked state, the pressure of the fluid also acts on the lock piston 56 to lock the piston. In order to cause the piston 56 to stroke against the urging force of the lock spring 58, the tip 56a of the lock piston 16 comes out of the groove 54b of the cushion ring 54, and the piston rod 5
The lock state of the lock piston 3 and the lock piston 56 is released, and at the same time, the piston 52 and the piston rod 53 stroke in opposite directions by the action of the fluid pressure, as shown in FIG. In this manner, the hydraulic cylinder with lock device 50 can automatically lock and unlock the piston at the stroke end of the piston.

However, a three-position closed center perfect valve is used as a valve for supplying and discharging fluid to the rod side and head side ports of the fluid pressure cylinder, and the valve is set to a normally closed position in the event of an emergency stop or the like. In some cases, the operation of the piston is stopped by closing the both ports on the rod side and the head side of the fluid pressure cylinder and sealing the pressure in the fluid pressure cylinder. In such a case, the conventional hydraulic cylinder 50 with a lock device is used.
Then, there is a problem that the lock is not applied in some cases.

That is, in the hydraulic cylinder 50 with the lock device, the lock piston 56 does not move to the lock position unless the residual pressure in the pressure chamber 61 on the side with the end lock mechanism is exhausted. Is switched to the normally closed position to close both the rod side and head side ports of the hydraulic cylinder, the pressure in the pressure chamber 61 is discharged even if the piston 52 of the hydraulic cylinder is near the stroke end position. If the valve is operated immediately before the operation and the fluid pressure is kept sealed in the pressure chamber 61, the lock piston 56 does not move to the lock position, so that there is a problem that the lock is not applied.
In the hydraulic cylinder 50 with a lock device, when the cylinder 54 is in a locked state and both ports are evacuated and the pressure fluid is supplied to one of the cylinder port 63 pressure chambers 61, the piston 54 attempts to start the stroke. There is a problem that the groove 54b of the sleeve 54 at the tip of the piston rod 53 is locked to the tip 56a of the lock piston 56 and pressed down, so that the lock cannot be released.

[0008]

The object of the present invention is to close both ports on the rod side and the head side of a hydraulic cylinder by a three-position closed center perfect valve at an emergency stop or the like, and to seal the pressure in the hydraulic cylinder. It is an object of the present invention to provide a hydraulic cylinder with a lock device that can stably lock a piston even when the hydraulic cylinder is locked.
Another object of the present invention is to provide a hydraulic cylinder with a lock device that can be reliably unlocked when a working fluid is supplied to a port provided with a lock mechanism for unlocking. .

[0009]

In order to solve the above-mentioned problems, a hydraulic cylinder with a lock device according to the present invention has a head side and / or a rod side of a cylinder tube in which a piston is slidably fitted in an axial direction. A lock cylinder in which a lock piston is slidably inserted in the axial direction is connected, and a pressure chamber formed between the piston and the lock piston is connected to a cylinder port. A chamber in which a plurality of through holes are formed concentrically is provided on a piston rod to which the piston is fixed, and a steel ball having a diameter larger than the thickness of the sleeve is provided in the through hole. A projecting portion and a steel for pressing the steel ball from the outside of the sleeve to project inward in the locking cylinder by disposing the steel ball so as to be displaceable in the thickness direction as long as the steel ball does not fall off the sleeve. Each of the grooves is formed so as to allow the steel balls to protrude outward. The lock pistons are engaged with the steel balls fitted in the sleeve and protruded inward, and the steel balls are protruded outward and displaced inward. In a fluid pressure cylinder with a lock device in which the lock piston is urged toward the piston by a lock spring, the pressure chamber communicates with the atmosphere when the piston comes near the stroke end. An exhaust means for exhausting the exhaust gas is provided.

In the fluid pressure cylinder with a lock device, when the lock cylinder is connected to the head side of the cylinder tube, the exhaust means is connected to an axial through hole provided in the lock piston and to the through hole in the axial direction. A plunger that is slidably inserted and has one end protruding toward the pressure chamber and the other end having a through-hole blocking means for blocking communication between the pressure chamber and the outside; and blocking the plunger from the through-hole. It is suitable to comprise a plunger spring that biases in the direction, and a piston rod that presses the plunger in a direction to open the through hole when the piston comes near the stroke end on the head side. The through-hole blocking means is preferably a flange provided at an outer end of the plunger and provided with a seal member pressed around the through-hole of the lock piston.

In the hydraulic cylinder with a locking device, when the locking cylinder is connected to the rod side of the cylinder tube, the locking cylinder is fitted with the piston rod and the lock piston slidably in the axial direction. The lock piston has a through hole into which the piston rod is slidably inserted in the axial direction via a seal member, and the exhaust means is provided when the piston comes near the rod-side stroke end. It is preferable that the pressure chamber is an axial passage groove that bypasses a seal member between the lock piston and the piston rod and opens the pressure chamber to the atmosphere. A seal member for sealing between the lock piston and the piston rod is provided on an inner peripheral surface of a through hole of the lock piston, and the passage groove is provided on the piston rod and is at least longer than an axial length of the seal member. Preferably, it is a groove.

The hydraulic cylinder with a lock device according to the present invention is provided with exhaust means for exhausting the pressure chamber by communicating the pressure chamber to the outside when the piston comes near the stroke end on the head side or the rod side. Even when the 3-position closed center valve is switched to the normally closed position due to emergency stop, etc., both the rod side and head side ports of the hydraulic cylinder are closed, and the pressure is sealed in the hydraulic cylinder, the piston remains on the head side or the rod. When the pressure comes near the stroke end on the side, the pressure chamber can be opened to the atmosphere to discharge the enclosed fluid.

Accordingly, the discharge of the fluid allows the piston rod to move to the stroke end, and the lock piston is pushed by the urging force of the lock spring to reach the lock position. When the lock piston moves to the lock position, the steel ball enters the groove of the lock cylinder, and the inward displacement of the steel ball in the groove is regulated by the insertion portion of the lock piston. The piston rod is locked by engagement with the protrusion of the cylinder.

When the working fluid is supplied to the port provided with the lock mechanism for releasing the lock, the fluid pressure also acts on the lock piston to cause the lock piston to stroke against the urging force of the lock spring. Therefore, the insertion part of the lock piston comes out of the sleeve, the steel ball is allowed to displace inside the sleeve, the engagement between the steel ball and the projection of the locking cylinder is released, and the locked state of the piston rod is released. At the same time, the piston and the piston rod stroke in opposite directions by the action of the fluid pressure.

[0015]

1 to 3 show the configuration of an embodiment of a hydraulic cylinder with a lock device according to the present invention, and switch a three-position closed center valve to a normally closed position by an emergency stop or the like. This is to explain the operation principle when the rod side and the head side ports of the hydraulic cylinder are closed and the pressure is sealed in the hydraulic cylinder.

The hydraulic cylinder 1 with a locking device is provided with a locking piston 16 which is axially slidably fitted on the head side of a cylinder tube 10 in which a piston 6 is axially slidably fitted. The lock cylinder 15 in the cylinder mechanism 2 is connected via the head cover 3,
A pressure chamber 11 formed between the piston 6 and the lock piston 16 communicates with the cylinder port 3a, and a seal member 16b is interposed between the pressure chamber 11 and the inner peripheral surface of the lock cylinder 15. Thereby, the pressure chamber 11 and the atmospheric pressure chamber 17 in the lock cylinder 15 are airtightly shut off. An end of the locking cylinder 15 is closed by fixing a holding plate 19 having an opening for air release at the center with a retaining ring 29,
The above-mentioned atmospheric pressure chamber 17 is formed inside.

A sleeve 12 having a plurality of through holes 12a is fixed concentrically to the tip of the cushion ring 7 of the piston rod 9 to which the piston 6 is fixed. Large steel ball 13
It is disposed so as to be displaceable in the thickness direction as long as it does not fall off from the sleeve 12.
3 is provided around the sleeve 12 to protrude inward by pressing the same from outside the sleeve 12 and a groove 15b for allowing the steel ball 13 to protrude outward is provided around the lock piston 16.
An insertion portion 16a is provided for engaging the steel ball 13 that is fitted into the sleeve 12 and protruding inward, and that protrudes the steel ball 13 outward to restrict inward displacement. Urges the piston 6 side. The lock spring 22 is housed in the atmospheric pressure chamber 17, and the holding plate 19 serves as a spring seat for the lock spring 22 and a plunger spring 33 described later.

The hydraulic cylinder 1 with the lock device is
When the piston 6 comes to a stroke end position on the head side, the pressure chamber 11 is connected to an atmospheric pressure chamber 17 in the locking cylinder 15 and exhausted. The exhaust means is axially provided in the lock piston 16, and is slidably inserted into the through hole 16c. One end protrudes toward the pressure chamber and the other end includes the through hole 16c. A plunger 30 having a through-hole blocking means for blocking communication between the pressure chamber 11 and the atmospheric pressure chamber 17 due to the above, a plunger spring 33 for urging the plunger 30 in a direction for blocking the through-hole, The piston 6 presses the plunger 30 in a direction to open the through hole when the piston 6 comes near the stroke end on the head side. As the through hole blocking means, a flange portion 31 provided with a seal member 34 pressed around the through hole 16c of the lock piston 16 is provided.
Note that reference numeral 8 in the drawing denotes a cushion packing that cooperates with the cushion ring 8 to stop and stop the piston 6.

The operation principle when the 3-position closed center perfect valve is switched to the normally closed position by an emergency stop or the like, both the rod side and the head side ports of the hydraulic cylinder are closed, and pressure is sealed in the hydraulic cylinder. This will be described with reference to FIGS. When the working fluid is supplied to the port on the rod side through the three-position closed center valve, the piston 6 and the piston rod 9 discharge the fluid in the head side pressure chamber 24 and the fluid in the pressure chamber 11 from the cylinder port 3a. While moving to the right side of FIG. When the piston rod 9 approaches the stroke end, the tip of the sleeve 12 is inserted into the locking cylinder 15, and the steel ball 13 is accordingly moved by the protrusion 15 a of the locking cylinder 15 to the sleeve 12.
Is pressed from outside and protrudes inside.

At this time, as shown in FIG. 2, the lock piston 16 moves rightward against the urging force of the lock spring 22 due to the fluid pressure in the pressure chamber 11, but the plunger 30 moves to the plunger spring 33. Through hole 1
6c is urged in a direction to shut off the pressure chamber 11c.
Is shut off from the atmospheric pressure chamber 17 in the lock cylinder 15. That is, since the flange 31 of the plunger 30 is pressed against the wall surface of the lock piston 16 by the urging force of the plunger spring 33 via the seal member 34, the through-hole that allows the pressure chamber 11 to communicate with the atmospheric pressure chamber 17. 16c is airtightly shut off.

When the three-position valve is switched to the normally closed position near the stroke end, both ports on the rod side and the head side of the hydraulic cylinder are closed,
The pressure of the fluid on the rod side and the head side is sealed in the hydraulic cylinder. After the fluid pressure is sealed in the fluid pressure cylinder, the piston rod 9 continues to move rightward due to the pressure receiving area difference and the pressure difference, and the insertion portion 16a of the lock piston 16 is inserted into the sleeve 12 and the piston rod 9 9
Contacts the tip of the plunger 30 and pushes the plunger 30 rightward against the urging force of the plunger spring 33. Therefore, the flange 3 of the plunger 30
1 is separated from the wall surface of the lock piston 16 so that the through hole 1
When the pressure chamber 6c is opened and the pressure chamber 11 communicates with the atmospheric pressure chamber 17, the fluid in the pressure chamber 11 is exhausted through the atmospheric pressure chamber 17.

When the fluid in the pressure chamber 11 is exhausted, the piston rod 9 can move to the stroke end, and the lock piston 16 is biased by the lock spring 22 by discharging the fluid pressure sealed in the pressure chamber 11. Is pushed to the left. In this state, the sleeve 1
If 2 strokes, the steel ball 13 becomes the locking cylinder 1
5 to the groove 15b after passing through the projection 15a of the steel ball 1
3 is pressed at the tip of the insertion portion 16a and protrudes and displaces out of the sleeve 12, and the insertion portion 16a is
3 is inserted into the sleeve 12 by the urging force of FIG.
The piston rod is locked as shown in FIG. In this state, the inward displacement of the steel ball 13 that has entered the groove portion 15b is restricted by the insertion portion 16a of the lock piston 16, so that the steel ball 13 and the protrusion 15 of the locking cylinder 15 are formed.
a is engaged, and the locked state is maintained.

When a working fluid is supplied to the port 3a for releasing the lock, the fluid pressure also acts on the lock piston 16 to cause the lock piston 16 to stroke against the urging force of the lock spring 22. 1
6 is removed from the sleeve 12 and the steel ball 1 is inserted.
3 is allowed to move inward of the sleeve 12 and the steel ball 13
Is disengaged from the projection 15a of the locking cylinder 15, and the locked state of the piston rod 9 is released, and at the same time, the piston 6 and the piston rod 9 stroke in opposite directions by the action of the fluid pressure.

In a normal use state of the hydraulic cylinder with a lock device, when the working fluid is supplied to the port on the rod side via the three-position valve, the piston 6 and the piston rod 9 move the fluid in the head side pressure chamber 24. The fluid in the pressure chamber 11 moves to the right while being discharged from the cylinder port 3a, and when the piston rod 9 approaches the stroke end, the tip of the sleeve 12 is inserted into the locking cylinder 15 and, accordingly, The steel ball 13 is pressed from the outside of the sleeve 12 by the projection 15a of the locking cylinder 15 and projects inward.

When the pressure of the fluid in the pressure chamber 11 is high, the lock piston 16 moves rightward against the urging force of the lock spring 22 due to the pressure as shown in FIG. When the pressure of the fluid in the pressure chamber 11 is reduced by being discharged from the cylinder port 3a, the lock piston 16 moves leftward due to the urging force of the lock spring 22, so that the insertion portion 16a of the lock piston 16 is At the same time, the tip of the piston rod 9 contacts the tip of the plunger 30 and pushes the plunger 30 rightward against the urging force of the plunger spring 33. Thereby, the through hole 16c is opened, and the fluid in the pressure chamber 11 is exhausted not only from the cylinder port 3a but also from the through hole 16c.

When the fluid in the pressure chamber 11 is exhausted, the lock piston 16 is pushed to the left by the urging force of the lock spring 22, and when the sleeve 12 moves to the stroke end, the steel ball 13 is moved to the lock cylinder 15 Projection 15a
Passes through the groove 15b, so that the steel ball 13
The insertion portion 16a is pushed into the outside of the sleeve 12 by being pushed by the distal end of the sleeve 12 and is inserted into the sleeve 12 by the urging force of the lock spring 22, and reaches the lock position as shown in FIG.

By switching the three-position valve,
When the working fluid is supplied to the cylinder port 3a and the fluid is discharged from the port on the rod side, the fluid pressure of the working fluid also acts on the lock piston 16 and causes the lock piston 16 to move rightward against the urging force of the lock spring 22. The insertion portion 16a of the lock piston 16 is
And the displacement of the steel ball 13 to the inside of the sleeve 12 is allowed.
The engagement with 5a is released, and the locked state of the piston rod 9 is released, and at the same time, the piston 6 and the piston rod 9 stroke in opposite directions by the action of the fluid pressure.

FIG. 4 is a partial sectional view showing another embodiment in which the locking cylinder mechanism 2 of the hydraulic cylinder with a locking device according to the present invention is provided on the rod cover side. The hydraulic cylinder 1 with a locking device is provided with a locking cylinder 1 on the rod cover 4 side of a cylinder tube 10 in which a piston 6 is slidably inserted in the axial direction.
5 are connected. The lock cylinder 15 has a lock piston 16 and a piston rod 9 slidably inserted in the axial direction. The pressure chamber 11 formed between the piston 6 and the lock piston 16 has a cylinder port 4.
a, the lock piston 16 includes a through hole 16c into which the piston rod 9 is slidably inserted in the axial direction, and an outer peripheral surface of the piston rod 9 provided on an inner peripheral surface of the through hole 16c. A seal member 16d for sealing the space between the lock piston 16 and a seal member 16b for sealing between an inner peripheral surface of the lock cylinder 15 provided on the outer peripheral surface of the lock piston 16 are provided.
The pressure chamber 11 hermetically shuts off the pressure chamber 11 from the atmospheric pressure chamber 17 provided in the lock cylinder 15. More specifically, the seal member 16d includes an annular groove provided in the inner peripheral surface of the through hole 16c and an annular seal member mounted in the annular groove. And an annular seal member mounted on the annular groove.

A sleeve 42 also serving as a cushion ring is fixed to the piston rod 9 to which the piston 6 is fixed and the surface of the piston 6 on the rod side. The sleeve 42 has a plurality of through holes 12a formed at its tip. And the through hole 12
a, a steel ball 13 having a diameter larger than the thickness of the sleeve 42 is disposed so as to be displaceable in the thickness direction as long as the steel ball 13 does not fall off from the sleeve 12. 42 and a groove 1 for allowing the steel ball 13 to protrude outward.
5b are inserted around the lock piston 16 so as to engage the steel balls 13 which are fitted into the sleeve 12 and protrude inward, and which protrude the steel balls 13 outward to restrict the inward displacement. The lock piston 1 is provided with a portion 16a.
6 is urged toward the piston 6 by a lock spring 22.

The lock spring 22 is housed in an atmospheric pressure chamber 17 provided in the lock cylinder 15, and the atmospheric pressure chamber 17 communicates with the outside through a port 15b. Note that the protrusion 15 is provided in the lock cylinder 15.
a and the groove 15b, instead of being provided around each of the protrusions 15a and the groove 15b, as shown in FIG.
May be integrally fixed so as to straddle the locking cylinder 15 and the rod cover 4.

The hydraulic cylinder 1 with the lock device is
An exhaust means is provided for exhausting the pressure chamber 11 by communicating with the atmospheric pressure chamber 17 in the locking cylinder 15 when the piston 6 comes near the stroke end on the rod side. The exhaust means includes a shaft provided on the outer peripheral surface of the piston rod 9 for communicating the pressure chamber 11 with an atmospheric pressure chamber 17 in the locking cylinder 15 when the piston 6 comes near the rod-side stroke end. Direction groove 9a
It is. The passage groove 9a has at least the through hole 16c.
Is a passage groove in the axial direction longer than the axial length of the seal member 16d provided on the inner peripheral surface of the seal member. It can reach the atmospheric pressure chamber 17 side in the locking cylinder 15 over the member 16d, and the fluid in the pressure chamber 11 flows out to the atmospheric pressure chamber 17 through the passage groove 9a.

Next, the operating principle of the hydraulic cylinder with a lock device will be described. When the working fluid is supplied to the head-side port via the three-position valve, the piston 6 and the piston rod 9 move to the left while discharging the fluid in the pressure chamber 11 from the cylinder port 4a.
At this time, as shown in FIG. 4, the lock piston 16 moves to the left against the urging force of the lock spring 22 due to the fluid pressure in the pressure chamber 11, but the piston 6 and the piston rod 9 move on the rod side. Since it does not come near the end, the tip of the axial passage groove 9a provided in the piston rod 9 cannot reach the atmospheric pressure chamber 17 side in the lock cylinder 15 beyond the seal member 16d. . Therefore, the pressure chamber 11 is isolated from the atmospheric pressure chamber 17 in the lock cylinder 15.

When the three-position valve is switched to the normally closed position near the stroke end due to an emergency stop or the like, both the rod side and the head side ports of the hydraulic cylinder are closed, and the pressure of the fluid on the rod side and the head side is reduced. Enclosed in a hydraulic cylinder. Even after the fluid pressure is sealed in the fluid pressure cylinder, the piston rod 9 continues to move leftward due to the pressure receiving area difference and the pressure difference, and when the lock piston 16 comes near the rod-side stroke end, the lock piston 16 Since the distal end of the axial passage groove 9a provided in the pressure chamber 11 reaches the atmospheric pressure chamber 17 side beyond the sealing member 16d, the fluid in the pressure chamber 11 passes through the passage groove 9a to the atmospheric pressure chamber 17. leak.

When the fluid in the pressure chamber 11 is exhausted, the piston rod 9 can move to the stroke end, and the lock which has moved against the lock spring 22 by the pressure of the fluid sealed in the pressure chamber 11. Piston 16
Since the fluid sealed in the pressure chamber 11 is exhausted and the pressure is reduced, the pressure is pushed by the urging force of the lock spring 22 and moves rightward. In this state, the sleeve 4
If 2 strokes, the steel ball 13 becomes the locking cylinder 1
5 to the groove 15b after passing through the protrusion 15a of the steel ball 1
3 is pressed by the tip of the insertion portion 16a and is projected and displaced outside the sleeve 12, and the insertion portion 16a is
Is inserted into the inside of the sleeve 42 by the urging force, and returns to the locked position. In this state, the inward displacement of the steel ball 13 that has entered the groove 15b is regulated by the insertion portion 16a of the lock piston 16, so that the steel ball 13 engages with the protrusion 15a of the locking cylinder 15. , The piston rod 9 is locked.

When the working fluid is supplied to the port provided with the lock mechanism for releasing the lock, the fluid pressure also acts on the lock piston 16 and pushes the lock piston 16 against the urging force of the lock spring 22. The insertion portion 16a of the lock piston 16 is
2, the steel ball 13 is allowed to be displaced inward of the sleeve 12, the engagement between the steel ball 13 and the projection 15a of the locking cylinder 15 is released, and the locked state of the piston rod 9 is released. At the same time, the action of the fluid pressure causes the piston 6 and the piston rod 9 to stroke in opposite directions.

In a normal use state, the working fluid is alternately supplied or discharged to a port on the rod side or the head side of the hydraulic cylinder via a three-position valve. When the working fluid is supplied to the port on the head side via the valve, the piston 6 and the piston rod 9 move to the left while discharging the fluid in the pressure chamber 11 from the cylinder port 4a. When the lock piston 16 moves to the vicinity of the stroke end on the rod side, the tip of the axial passage groove 9a provided in the piston rod 9 reaches the atmospheric pressure chamber 17 side beyond the seal member 16d. The fluid in the pressure chamber 11 is exhausted not only from the cylinder port 4a but also from the passage groove 9a.

When the fluid pressure in the pressure chamber 11 is high,
As shown in FIG. 4, the lock piston 16 moves leftward against the urging force of the lock spring 22 due to the back pressure on the rod side, but when the fluid in the pressure chamber 11 is exhausted, the piston rod 9 moves The lock piston 16 can be moved to the end, and the lock piston 16 is pushed by the urging force of the lock spring 22 to move rightward because the fluid in the pressure chamber 11 is exhausted and the fluid pressure decreases. If the sleeve 42 further strokes in this state, the steel ball 13
Pass through the projection 15a of the locking cylinder 15 and
b, the steel ball 13 is pressed by the tip of the insertion portion 16a and protrudes and displaces out of the sleeve 12, and the insertion portion 16a is inserted into the sleeve 42 by the urging force of the lock spring 22, and returns to the locked position. I do. In this state, the inward displacement of the steel ball 13 that has entered the groove 15b is regulated by the insertion portion 16a of the lock piston 16, so that the steel ball 13 engages with the protrusion 15a of the locking cylinder 15. , The piston rod 9 is locked.

When the position of the valve body of the three-position valve is switched to supply the working fluid to the cylinder port 4a and discharge the fluid from the port on the head side, the pressure of the working fluid also acts on the lock piston 16 to lock. In order to move the piston 16 to the left against the urging force of the lock spring 22, the insertion portion 16a of the lock piston 16 comes out of the sleeve 12, and the steel ball 13 is allowed to displace inside the sleeve 12, and the steel ball 13 is displaced. The engagement between the lock 13 and the projection 15a of the locking cylinder 15 is released, and the locked state of the piston rod 9 is released, and at the same time, the piston 6 and the piston rod 9 stroke in opposite directions by the action of the fluid pressure.

As described in detail above, in the hydraulic cylinder with a lock device according to the present invention, the three-position valve is switched to the normally closed position upon an emergency stop or the like, and both the rod side and the head side of the hydraulic cylinder are operated. Even when the port is closed and the pressure of the fluid on the rod side and the head side is sealed in the fluid pressure cylinder, or under normal use,
Even when the working fluid is alternately supplied or discharged to the port on the rod side or the head side of the hydraulic cylinder, the piston can be locked at the stroke end of the piston or the lock can be reliably released. .
For example, in the conventional hydraulic cylinder with a lock device 50 shown in FIGS. 5 to 7, when the cylinder is locked and both ports are exhausted, the groove 54 b of the sleeve 54 fixed to the tip of the piston rod 53 is There was a problem that the lock could not be released even if the lock piston was pinched and pressed to supply the pressure fluid to the port 63 on the side with the lock mechanism. However, the hydraulic cylinder with the lock device was actually manufactured and tested. As a result, it was confirmed that the fluid pressure cylinder with the lock device according to the present invention can reliably release the lock at the stroke end when the air pressure of 0.1 Mpa or more is supplied to the unlocking port even when both ports are in the exhaust state. .

[0040]

As described in detail above, according to the present invention, in the event of an emergency stop or the like, the three-position valve closes both the rod-side port and the head-side port of the hydraulic cylinder to apply pressure to the hydraulic cylinder. A hydraulic cylinder with a lock device that can lock the piston even when sealed, and can be securely unlocked when working fluid is supplied to the port with the lock mechanism for unlocking. Can be provided.

[Brief description of the drawings]

FIG. 1 is a partial sectional view showing one embodiment of a hydraulic cylinder with a lock device according to the present invention.

FIG. 2 is a partial cross-sectional view of the same embodiment at an operation position different from that of FIG. 1;

FIG. 3 is a partial cross-sectional view at an operation position different from those in FIGS. 1 and 2 in the embodiment.

FIG. 4 is a partial sectional view showing another embodiment of the hydraulic cylinder with a lock device according to the present invention.

FIG. 5 is a partial sectional view showing a conventional hydraulic cylinder with a lock device.

FIG. 6 is a partial cross-sectional view at an operation position different from that in FIG. 5;

FIG. 7 is a partial cross-sectional view at an operation position different from FIGS. 5 and 6;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fluid pressure cylinder with a lock device 3a, 4a Cylinder port 6 Piston 9 Piston rod 10 Cylinder tube 11 Pressure chamber 12 Sleeve 13 Steel ball 15 Locking cylinder 15a Projection 15b Groove 16 Lock piston 17 Atmospheric pressure chamber

Claims (5)

[Claims] A locking cylinder in which a lock piston is slidably inserted in an axial direction is connected to a head side and / or a rod side of a cylinder tube in which a piston is slidably inserted in an axial direction. A pressure chamber formed between the piston and the lock piston is communicated with the cylinder port, and the lock piston airtightly shuts off the pressure chamber from the outside. A sleeve provided with a hole is provided concentrically, and a steel ball having a diameter larger than the thickness of the sleeve is disposed in the through hole so as to be displaceable in a thickness direction within a range in which the steel ball does not fall off the sleeve. Inside, a projection for pressing the steel ball from the outside of the sleeve to protrude inward and a groove for allowing the steel ball to protrude to the outside are respectively provided around the lock piston. An insertion portion is provided for engaging the steel ball that has been inserted and protruded inward, and for protruding the steel ball outward to restrict inward displacement, and urges the lock piston toward the piston by a lock spring. In the fluid pressure cylinder with a lock device, exhaust means for exhausting the pressure chamber by communicating with the atmosphere when the piston comes near the stroke end is provided.
A fluid pressure cylinder with a lock device. 2. The hydraulic cylinder with a lock device according to claim 1, wherein the lock cylinder is connected to a head side of the cylinder tube, and the exhaust means is provided in an axial direction provided on the lock piston. A plunger having a through hole, a through hole slidably inserted into the through hole, one end protruding toward the pressure chamber and the other end blocking through hole blocking means for blocking communication between the pressure chamber and the outside; A plunger spring for urging the jar in a direction to block the through hole, and a piston rod for pressing the plunger in a direction to open the through hole when the piston comes near the stroke end on the head side. A fluid pressure cylinder with a lock device. 3. The hydraulic cylinder with a lock device according to claim 2, wherein the through hole blocking means is provided at an outer end of the plunger, and includes a seal member pressed around the through hole of the lock piston. A fluid pressure cylinder with a lock device, characterized in that it is a flange provided. 4. The hydraulic cylinder with a lock device according to claim 1, wherein the lock cylinder is connected to the rod side of the cylinder tube, and the piston rod and the lock piston are slidably inserted in the axial direction. The lock piston has a through hole through which the piston rod is slidably inserted in the axial direction via a seal member. The exhaust means is configured such that the piston comes near a rod-side stroke end. A fluid pressure cylinder with a lock device, characterized in that it is an axial passage groove that opens the pressure chamber to the atmosphere by bypassing a seal member between the lock piston and the piston rod when the lock piston is in a closed state. 5. The hydraulic cylinder with a lock device according to claim 4, wherein a seal member for sealing between the lock piston and the piston rod is provided on an inner peripheral surface of a through hole of the lock piston, and the passage is provided. The groove provided in the piston rod and being longer than at least the axial length of the seal member.