JP2696187B2 - Booster type hydraulic cylinder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic cylinder such as an air cylinder and a hydraulic cylinder, and more particularly to a pressure-increasing hydraulic cylinder which increases the operating force near the end of pushing a piston rod.

[0002]

2. Description of the Related Art Fluid pressure cylinders are used in various operating mechanisms such as a clamp mechanism, a compression mechanism, and a caulking mechanism.
At the start of operation, little operating force is required, but in the vicinity of the end of operation, a large amount of operating force is required in many cases. For this reason, the hydraulic cylinder that drives the mechanism is located near the end of pushing out the piston rod. Therefore, it is necessary to generate a larger operating force than the start position and the intermediate position.

For this reason, when determining the size of a hydraulic cylinder used for a clamp mechanism or the like, a hydraulic cylinder having a size (diameter of a cylinder tube) large enough to obtain a necessary operating force at the end of the operation is required. It is usually chosen. Therefore, even if a small (small cylinder tube diameter) fluid pressure cylinder is sufficient from the start of pushing out the piston rod to just before the end, even if a small (small cylinder tube diameter) hydraulic cylinder is sufficient, the end working force is large, heavy and expensive. There was a problem that a hydraulic cylinder had to be used.

[0004]

Therefore, conventionally, a booster device is connected to a pipeline for supplying a fluid pressure to a fluid pressure cylinder, and a higher pressure is applied near a pushing end position of a piston rod. The actuation force is increased near the end.

However, this type of booster has a problem that the structure is complicated and at least four solenoid valves need to be used, which increases the cost.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an increased pressure can be exerted in the vicinity of the pushing end of a piston rod. It is an object to provide a hydraulic cylinder.

[0007]

For this purpose, the booster type hydraulic cylinder of the present invention is provided with an auxiliary cylinder outside the rod cover.
An auxiliary cylinder chamber is formed by providing a cylinder tube and an auxiliary rod cover, and a booster piston is disposed in the auxiliary cylinder chamber so as to be slidable in the axial direction on the outer peripheral portion of the piston rod. Is connected to the air supply / exhaust port to assist
A passage for passing fluid pressure is formed in the cylinder chamber to supplement the passage.
Provide a valve seat at the end on the auxiliary cylinder chamber side and
A valve is formed by attaching a sealant to the opposing surface of the
Coil spring arranged between auxiliary rod cover and booster piston
Is a space having a tapered surface on the inner side of the pressure increasing piston around the piston rod is formed, locking steel balls for locking the booster piston to the piston rod is disposed on the space outer circumferential portion of the piston rod Of the piston rod
Immediately before the end of the extrusion, the pressure contact
A step is provided to open the valve section by pressing the ton.
Unlock the door cover toward the lock steel ball in the space
The part is protrudingly provided.

[0008]

The fluid pressure is applied to the cylinder chamber between the head cover and the piston, and the piston and the piston rod are driven in the pushing direction. At this time, when the piston rod reaches just before the end of extrusion, the step on the outer periphery of the piston rod
Abuts on the booster piston and pushes the booster piston.
The valve part opens more. For this reason, fluid pressure enters between the booster piston in the auxiliary cylinder chamber and the rod cover from the passage in the rod cover, and pushes the booster piston in the direction of the piston rod, while the locking steel ball inside the booster piston is in the space. The inner pressure is strongly pressed against the outer periphery of the piston rod by the tapered surface, and the pressure-intensifying piston is locked to the piston rod. As a result, while the piston rod is thereafter pushed to the end position, the operating force of the pressure-intensifying piston receiving fluid pressure and moving is added to the operating force of the piston rod, and the operating force of the piston rod is increased near the pushing end. You. On the other hand, when the piston rod pulls back,
Intensifier piston is also pulled back by coil spring and fluid pressure
The lock release part moves relatively to the locking direction.
By pressing the steel ball piston for locking in space
The lock on the rod is released and the piston rod is
Move away from the ston to the retraction end.

[0009]

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

FIG. 1 is a plan view of a hydraulic cylinder, and FIG. 2 is an enlarged sectional view taken along the line II-II of FIG. A head cover 2 is fixed to the end of the cylinder tube 1 so as to close the end, and a rod cover 4 is fixed to the tip side of the cylinder tube 1 so as to slidably support the piston rod 6 and close the tube opening. Is done. Further, the auxiliary cylinder tube 1a is connected and fixed to the outside of the rod cover 4, and the auxiliary rod cover 3 is fixed to the tip of the auxiliary cylinder tube 1a so as to close the end and slidably support the piston rod 6. , Auxiliary cylinder tube 1a
An auxiliary cylinder chamber 21 is formed therein.

A piston 5 is inserted into the cylinder tube 1 and a piston rod 6 fixed to the piston 5
As shown in FIG. 2, a large diameter portion 6a is provided at the base, and a rod having a normal thickness is extended from the large diameter portion 6a to the distal end via a tapered step portion 6b. You.

The rod cover 4 is provided at the center with a hole through which the piston rod 6 is inserted. The hole is formed to have a diameter through which the large-diameter portion 6a of the piston rod 6 can slide tightly.
The seal member 7 is fitted on the inner peripheral side of the hole. In the center of the auxiliary rod cover 3, a hole for slidably supporting the piston rod 6 is also provided in the auxiliary cylinder tube 1a between the rod cover 4 and the auxiliary rod cover 3 in which the bearing metal 8 and the seal member 9 are fitted. That is, the pressure-intensifying piston 10 is slidably fitted into the auxiliary cylinder chamber 21. A coil spring 11 is disposed between the pressure-intensifying piston 10 and the auxiliary rod cover 3, and the pressure-increasing piston 10 is urged by the coil spring 11 to the right side in FIG.

In the pressure-intensifying piston 10, a piston rod 6 is inserted into a hole formed in the center axis direction, and a contact portion 10a in which the step 6b of the piston rod 6 comes into contact with the outer periphery of the hole.
Is formed. Further, a tapered surface (conical inclined surface) 12 is provided around the piston rod 6 and inside the pressure-intensifying piston 10.
A space (substantially conical recess) 12 having a is formed. The space 12 is located so as to surround the periphery of the piston rod 6, and the tapered surface 12 a is formed so that the angle is widened toward the distal end side of the piston rod 6.

Further, in the space 12, for example, eight locking steel balls 13 are disposed so as to surround the periphery of the piston rod 6. The locking steel ball 13 has an outer diameter capable of contacting the tapered surface 12a and the outer peripheral surface of the piston rod when the large-diameter portion 6a of the piston rod 6 enters the space 12 of the pressure-intensifying piston 10. . A seal member 14 is fitted on the outer peripheral portion of the pressure-intensifying piston 10, and a seal member 15 is fitted on the inner peripheral portion thereof.

Further, on the side of the auxiliary cylinder chamber 21 of the rod cover 4, a lock releasing part 17 for releasing the lock by pushing the locking steel ball 13 to the distal end side when the piston rod 6 is pulled back is provided in the space 12. It is protruded so as to be inserted.

The rod cover 4 is provided with a supply / exhaust port 25 communicating with the cylinder chamber 20 through a passage 27.
Further, a supply / exhaust port 26 communicating with the auxiliary cylinder chamber 21 through the passage 28 is provided. A valve seat 29 is formed at the opening end of the passage 28 on the side of the auxiliary cylinder chamber 21, and the seal member 16 is fitted on the pressure-increasing piston side facing the valve seat 29. With the pressure-intensifying piston 10 in contact with the rod cover 4, the sealing material 16 comes into close contact with the valve seat 29 and the passage 28
Close the opening. That is, the sealing material 16 and the valve seat 29
Thereby, a valve portion is formed.

A passage 30 communicating with the auxiliary cylinder chamber 21 is formed in the auxiliary rod cover 3 at the distal end, and this passage 30 communicates with a passage 27 communicating with the cylinder chamber 20 via a pipe 31. On the other hand, a supply / exhaust port 24 communicating with the base side of the cylinder chamber 20 is provided in the head cover 2 at the base (FIG. 1).

Next, the operation of the fluid pressure cylinder having the above configuration will be described.

Both the supply / exhaust port 26 and the supply / exhaust port 24 are connected to one port of a directional control valve connected to a fluid pressure source, and the supply / exhaust port 25 is connected to the other port of the directional control valve. .

When the directional control valve is switched and the fluid pressure is applied to the supply / exhaust ports 24 and 26 with the piston rod 6 in the retracted position or the intermediate position (FIG. 2), the piston 5 moves to the left in FIG. The piston rod 6 advances in the pushing direction by receiving the operating force in the direction. At this time, the fluid pressure is also applied to the passage 28 through the air supply / exhaust port 26 and pushes the pressure-intensifying piston 10 leftward in FIG. 2, but the spring force of the coil spring 11 exceeds and the pressure-increasing piston 10 does not move. The piston rod 6 advances to the left in FIG. 2, and when the stepped portion 6 b enters the space 12 in the pressure-intensifying piston 10 from the rod cover 4, the tapered step causes each locking steel ball 13 to become a large diameter portion. Continue to the left while lifting around 6a.

When the piston rod 6 reaches the position shown in FIG.
a, whereby the pressure-intensifying piston 10 is pushed to the left and starts moving. Then, the back surface (seal member 16) of the pressure-intensifying piston 10, which is in close contact with the valve seat 29, separates, and the fluid flows into the auxiliary cylinder chamber 21 from the passage 28. By this fluid pressure, the pressure-intensifying piston 10 is pushed to the left,
At the same time, the pressure fluid also enters the space 12.

When the pressure-increasing piston 10 is moved to the left (the direction in which the piston rod 6 is pushed out) by being pushed by fluid pressure, the locking steel ball 13 in the space 12 is made larger by the tapered surface 12a. It is strongly pressed against the outer periphery of the portion 6a. Therefore, the pressure-intensifying piston 10 is locked to the piston rod 6 by the locking steel ball 13.

Therefore, the piston rod 6 which has reached the position shown in FIG. 5 is pushed out by applying the operating force of the pressure-intensifying piston 10 together with the operating force applied to the piston 5.
That is, just before the end of the pushing, the operating force of the piston rod 6 is increased by the pressure receiving area of the pressure-intensifying piston 10, and in a state where the pressure is increased, the piston rod 6 is pushed to the end.

On the other hand, when the piston rod 6 is pulled back, the direction switching valve is switched to apply fluid pressure from the supply / exhaust port 25, and the supply / exhaust port 26 is communicated with the exhaust side. As a result, the pressure on the rear side of the pressure-intensifying piston 10 is released, and the pressure-increasing piston 10 returns to the right in FIG. 5 together with the piston rod 6, and the position in FIG. When the pressure-intensifying piston 10 returns to the contact position, the locking steel ball 13 is
7 to the left side of the drawing to move,
Of the piston rod 6 is released.

The piston rod 6 is connected to the piston 5
Is pulled back from the cylinder chamber 20 to the distal end by the rightward pressure received at its front face.

If the diameter of the auxiliary cylinder tube 1a in the auxiliary cylinder chamber is made larger than the diameter of the cylinder tube 1 and the diameter of the pressure-intensifying piston is increased, the pressure receiving area is increased and the end of the piston rod ends. In the vicinity, the operating force can be further increased.

[0027]

As described above, according to the pressure-intensifying type hydraulic cylinder of the present invention, when the piston rod reaches just before the end of the pushing, the pressure-increasing piston and the rod in the auxiliary cylinder chamber pass through the passage in the rod cover. Since fluid pressure enters between the covers and pushes the pressure-intensifying piston in the direction in which the piston rod is pushed out, a steel ball for locking in the space of the pressure-increasing piston is configured to lock the pressure-intensifying piston with respect to the piston rod. While the piston rod is pushed out from there to the end position, the operating force of the booster piston receiving fluid pressure is added to the operating force of the piston, and the operating force of the piston rod near the end of extrusion is transferred to a hydraulic cylinder of the same diameter. It can be increased more. In addition,
Locking steel ball with tapered surface in space provided in pressure piston
By pressing to lock, a strong locking force is obtained .
A valve is installed at the end of the passage provided in the rod cover.
Only, and the step difference portion of the piston rod presses the pressure increasing piston
When the valve is opened, the fluid pressure acts on the booster piston.
The piston detector and the solenoid valve in the fluid pressure line.
The id valve can be omitted .

[Brief description of the drawings]

FIG. 1 is a plan view of a hydraulic cylinder showing one embodiment of the present invention.

FIG. 2 is an enlarged sectional view taken along line II-II of FIG.

FIG. 3 is a sectional view taken along line III-III of FIG. 2;

FIG. 4 is a cross-sectional view of a state where a step portion of a piston rod has contacted a pressure-intensifying piston.

FIG. 5 is a cross-sectional view showing a state where the pressure-intensifying piston is locked to a piston rod via a locking steel ball.

[Explanation of symbols]

4-rod cover, 5-piston, 6-piston rod, 10-pressure booster piston, 12-space, 12a-tapered surface, 13-locking steel ball, 21-auxiliary cylinder chamber, 28
-Passages.

Claims (1)

(57) [Claims] An auxiliary cylinder tube is provided outside the rod cover.
Formed auxiliary cylinder chamber by providing over blanking the auxiliary rod cover, the auxiliary cylinder pressure intensifying piston in chamber is slidably disposed in the axial direction at the outer peripheral portion of the piston rod, sheet in said rod cover The auxiliary system communicates with the exhaust port.
A passage for passing fluid pressure is formed in the cylinder chamber, and a supplementary passage for the passage is formed.
Provide a valve seat at the end on the auxiliary cylinder chamber side, and
A valve is formed by attaching a sealant to the opposite surface of the ston.
Between the auxiliary rod cover and the booster piston.
Roots are disposed, a space is formed with a tapered surface on the inside of the bulking pressure piston around the piston rod, in this space
Is provided with a locking steel ball for locking the pressure-intensifying piston to the piston rod, and an outer peripheral portion of the piston rod.
Before the end of the push out of the piston rod.
Abuts on the ston and pushes the booster piston to release the valve
An open step portion is provided, and the rod cover is provided in the space.
A pressure-intensifying fluid pressure cylinder, wherein an unlocking portion is protruded toward the locking steel ball .