JP2000065013A - Speed control of pneumatic cylinder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To smoothly control a speed even at a high speed by changing an air flow by driving a valve rod of a flow control valve by the inclined face parts of cams interlocking with a piston rod. SOLUTION: In a state where a piston rod 1a exists in a drawing-back position and cams 4 push in a valve rod 5a to a maximum, when compressed air is supplied to an air vent A by passing through a flow control valve 5, the piston rod 1a moves outward at a low speed together with the cams 4, and an air flow increases by a return movement of the valve rod 5a brought into pressure contact with the inclined face part 4a, so that a speed of the piston rod 1a increases. The other inclined face part 4a starts to push in the valve rod 5a in the vicinity where the piston rod 1a finishes an outward movement, and when a supply air flow of the air vent A reduces, the piston rod 1a reduces in a speed. The piston rod 1a can be controlled on a speed in an optional position between strokes by setting a shape of the inclined face part 4a. When the piston rod 1a moves inward by supplying the compressed air to an air vent B, the flow control valve 5 controls an exhaust flow from the air vent A.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to speed control of a pneumatic cylinder for mechanically controlling a moving speed of a piston operated by using a fluid pressure such as compressed air.

[0002]

2. Description of the Related Art In conventional speed control of a pneumatic cylinder, a flow rate control valve for a fluid (hereinafter, referred to as air) communicating with the cylinder is manually adjusted, or a flow rate is controlled for a cushion effect at a piston stroke end portion. It had a built-in control ventilation circuit.

[0003]

In conventional speed control of a pneumatic cylinder, it is difficult to control the flow rate of air supply and exhaust in relation to the position of movement of the piston. There is a problem that the conveyed object receives an impact particularly at a high speed due to a large speed change.

SUMMARY OF THE INVENTION An object of the present invention is to provide a speed control of a pneumatic cylinder capable of smoothly controlling a speed even at a high speed by changing an air flow rate in conjunction with a movement position of a piston.

[0005]

In order to achieve the above object, in a speed control of a pneumatic cylinder according to the present invention, for example, in a direct acting cylinder, a joint and a cam base are provided on a piston rod forming one end of a piston. The air flow rate is controlled by driving the valve rod of the flow control valve by pressing against the inclined surface of the cam mounted via the valve. The slope of the cam may be flat or curved. Also,
When the valve stem of the flow control valve is pushed in, the air flow rate may decrease or increase depending on the shape of the cam slope. In the case of an oscillating cylinder, a disc-shaped cam is attached to the oscillating and rotating piston shaft.

The flow control valve controls the air flow rate by changing the clearance area between the tip end of the valve stem and the slot hole by moving the valve stem driven by the cam. The mounting position of the flow rate control valve may be on both sides of the air supply side and the exhaust side of the cylinder vent, or any one side. The cam mounted on the cam base is provided at a position where control is required in the stroke of the piston rod. Further, a cam base plate may be interposed between the cam and the cam base.

In order to change the moving speed of the piston rod in a cam curve (for example, a modified sinusoidal curve), the slope of the cam is set to a desired cam curved surface, and the relationship between the moving distance of the valve rod and the air flow rate is roughly determined. It is better to make it directly proportional. When the moving distance of the piston rod and the moving distance of the valve rod are approximately directly proportional, the tip of the valve rod is deformed to change the air flow rate in a cam curve.

[0008] The control of the air flow rate changes the gap by inserting and moving the tapered tip of the valve stem into the slot hole. Further, the tip of the valve stem may have a curved conical shape, and the air flow rate may be changed in a cam curve.

If an electromagnetic switching valve is provided between the flow control valve and the cylinder vent and the other can be vented, the supply and exhaust are not restricted by the flow control valve. Is faster than during control.

[0010] The positional relationship between the cylinder, the flow control valve, and the cam base is kept constant via the frame.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described based on embodiments with reference to the drawings. In FIG. 1, a cam 4 is mounted via a joint 2 and a cam base 3 in parallel or in parallel with a piston rod 1a fixed to a piston of a cylinder 1.
The valve stem 5 a of the flow control valve 5 communicating with the ventilation hole A of the cylinder 1 is disposed so as to be able to press against the slope 4 a of the cam 4. In this case, when the cam 4 pushes the valve stem 5a, the air flow rate is in a direction to decrease.

When the compressed air passes through the flow control valve 5 and is supplied to the vent hole A when the piston rod 1a is at the retracted position and the cam 4 has pushed the valve rod 5a to the maximum, the piston rod 1a moves out together with the cam 4 at a low speed, and the return movement of the valve rod 5a pressed against the slope 4a increases the air flow rate, thereby increasing the velocity of the piston rod 1a. In the vicinity of the end of the movement of the piston rod 1a, if the other slope 4a starts pushing the valve rod 5a and the flow rate of air supplied to the ventilation hole A decreases, the piston rod 1a moves up. Also, by setting the shape of the slope 4a,
The speed of the piston rod 1a can be controlled at an arbitrary position between strokes. When the compressed air is supplied to the vent hole B and the piston rod 1a enters and moves, the flow control valve 5 controls the exhaust flow rate from the vent hole A.

In the embodiment shown in FIG. 2, the flow control valve 5
Is provided in the ventilation hole B.

In the embodiment shown in FIG. 3, the flow control valve 5
Are provided on both sides of the ventilation hole A and the ventilation hole B.

In the embodiment shown in FIG. 4, an electromagnetic switching valve 7 is provided in the ventilation pipe 6 between the ventilation hole A and the flow control valve 5, and the ventilation is opened to the ventilation pipe 6a.

In FIG. 5, the valve stem tip 5b is inserted and moved into the slot hole 5c to control the flow rate of air between the ventilation holes C and D.

[0017]

Since the present invention is configured as described above, the following effects can be obtained. Since the valve stem of the flow control valve is reliably driven on the slope of the cam that is linked to the movement of the piston rod, even without using electrical control or shock absorbing devices,
Smooth speed control that minimizes the impact on conveyed objects during high-speed movement has become possible.

[Brief description of the drawings]

FIG. 1 is a perspective view of speed control of a pneumatic cylinder.

FIG. 2 is a perspective view showing an embodiment of mounting a flow control valve.

FIG. 3 is a perspective view showing an embodiment of mounting a flow control valve.

FIG. 4 is a perspective view showing a mounting example of an electromagnetic switching valve.

FIG. 5 is a longitudinal sectional view showing an embodiment of the flow control valve.

[Explanation of symbols]

 1a Piston rod Cam base Cam 4a Slope Flow control valve 5a Valve rod 5b Valve rod tip 5c Slot hole

Claims (3)

[Claims] 1. A valve rod (5) of a flow control valve (5) is provided on a slope (4a) of a cam (4) interlocked with a piston rod (1a).
a) Speed control of the pneumatic cylinder driving the. 2. The speed control of a pneumatic cylinder according to claim 1, wherein the slope (4a) is a curved surface. 3. The speed control of a pneumatic cylinder according to claim 1, wherein the valve stem tip (5b) of the valve stem (5) is curved and deformed.