JP2000170713A - Cylinder with position detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cylinder with a position detector which can detect both stroke ends (position) by securing short space and attain shortening of whole length of mounting equipment and devices. SOLUTION: Knob type position detection members 18A, 18B, which can be moved to the direction in parallel with the direction of reciprocal motion of a piston 14 and of which one end side is normally moved and enforced to be protruded into a cylinder body 13 through elastic bodies 21A, 21B, are supported in a head cover 11 and a rod cover 12 at the ends of axis direction of the cylinder body 13, respectively. The knob type position detection members 18A, 18B are constructed to abut on the piston 14 when the piston 14 reaches close to the end of the direction of reciprocal motion, and to be pressed and moved to the direction for detection of position against the energizing force of elastic bodies 21A, 21B in accordance with the movement of the piston 14 to the stroke end afterward.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cylinder with a position detecting device which is used, for example, when a valve body or the like in an on-off valve is switched between a fully opened position and a fully closed position.

[0002]

2. Description of the Related Art Heretofore, for example, a cylinder having a structure as shown in FIG. That is, a piston rod 3 for operating a driven body (not shown) such as a valve body of an on-off valve is fixedly connected to a piston 2 fitted and held in a cylinder body 1 so as to be able to reciprocate in the axial direction.

A cam 4 is directly attached to the piston rod 3 or a cam is attached to a guide rod (not shown) which moves in synchronization with the piston 2.
2 at a distance L equal to the cylinder stroke
The two limit switches 5A and 5B are arranged, and when the piston 2 reaches the end (stroke end) in the reciprocating direction, the limit switch 5A or 5B is operated by the cam 4 which moves integrally with the piston 2 and the piston rod 3. Thereby, the stroke end of the cylinder is detected.

[0004]

In the conventional cylinder with a position detecting device having the above-described structure, when the limit switches 5A and 5B are arranged, the same distance L as the piston rod 2 or the guide rod moves by a full stroke. Space is required, and the length of the device and equipment on which the cylinder is mounted is long, so that there is a problem that the apparatus tends to be uneconomical.

[0005] The present invention solves the above-mentioned problems, and secures a short space so that both stroke ends (positions) are reduced.
It is an object of the present invention to provide a cylinder with a position detecting device that can detect the position of the mounting device and the length of the device.

[0006]

In order to solve the above-mentioned problems, a cylinder with a position detecting device according to the present invention has a piston fitted and held in a cylinder body so as to be reciprocally movable in an axial direction. Cylinder connected with a piston rod for driven body operation,
At each end of the cylinder body in the axial direction, a knob-shaped position detection member is supported so as to be movable in a direction parallel to the reciprocating direction of the piston. An elastic body is provided to move and urge to protrude, and when the piston reaches near the end in the reciprocating direction, the piston comes into contact with one end of the knob-shaped position detecting member to elastically move the knob-shaped position detecting member. It is configured to be pressed and moved in the position detection direction against the urging force of the body.

With the above structure, the two knob-shaped position detecting members are supported by moving and biasing both ends of the cylinder body in the axial direction so that one end of the cylinder body usually projects into the cylinder body. When the piston moves from near the end to the end in the reciprocating direction, the knob-shaped position detecting member is pressed by the piston and moved in the position detecting direction against the urging force. It is possible to detect both stroke ends (two positions) of the cylinder by detecting the movement of the state position detecting member in the position detecting direction. Therefore, it is not necessary to provide a space having a distance equal to the full stroke of the cylinder for position detection, and the length of the device and equipment on which the cylinder including the position detection member is mounted is short, so that it can be installed and used economically. Can be.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an external side view of an entire cylinder with a position detecting device according to the present invention, and FIG. 2 is a vertical side view of the cylinder. In the cylinder C, a piston 14 that can reciprocate in the axial direction along with the supply and discharge control of a pressure fluid such as water or air is provided in a cylinder body 13 in which a head cover 11 and a rod cover 12 are fixed at both ends in the axial direction. The piston 14 is fitted and held.
One end of a piston rod 15 for operating a driven body such as a valve body in an on-off valve is fixedly connected to the axial center portion of the on-off valve, and the other end of the piston rod 15 passes through a through hole 16 formed in the rod cover 12. It protrudes outward.

[0009] As clearly shown in FIG.
Through holes 17A and 17B are formed in the head cover 11 and the rod cover 12 at both ends in the axial direction at positions eccentric to the axis of the piston 14 in parallel with the reciprocating direction of the piston 14. These two through holes 1
7A and 17B, knob-shaped position detecting members 18A and 18B
Are air-tight and water-tight via O-rings 19A and 19B, and are movably supported in a direction parallel to the reciprocating direction of the piston 14.

[0010] Head cover 11 and rod cover 12
Large-diameter hole portion 20 following through holes 17A and 17B formed in
A and 20B include both knob-shaped position detecting members 18A and 18B.
Normally, elastic bodies 21A and 21B such as a coil spring and a laminated disc spring which move and urge B so that one end thereof protrudes into the cylinder body 13 are housed and held. The other end sides of both knob-shaped position detecting members 18A and 18B are
Normally, as shown by the phantom line in FIG.
1 and the rod cover 12 are flush with or slightly outward from the outer surface.

The outer surface of the head cover 11 in or near the cylinder C and the rod cover 12
On or near the outer surface of the
A and 22B are fixedly arranged. The operation pieces 22a and 22b of these limit switches 22A and 22B are provided facing the movement path of the knob-shaped position detecting members 18A and 18B. When the piston 14 reaches near the stroke end, the operation of the knob-shaped position detecting members 18A and 18B is stopped. The knob-shaped position detecting members 18A and 18B are pushed and moved outward in the position detecting direction, that is, outwardly, against the urging force in accordance with the movement from the point of contact with one end to the end of the stroke. The movement of the detection members 18A, 18B causes the operation pieces 22a, 22b of the limit switches 22A, 22B to operate.

In the cylinder C with the position detecting device having the above structure, the piston 14 reciprocates in the axial direction with the control of the supply and discharge of the pressurized fluid into the cylinder body 13.
By the reciprocating motion of the piston rod 15, for example, the valve body of the on-off valve is switched between the fully open position and the fully closed position.

Here, when the piston 14 reaches the vicinity of the stroke end, the end face of the piston 14 contacts one end of the knob-shaped position detecting member 18A or 18B, and further moves toward the stroke end from the contact point. As a result, the knob-shaped position detecting member 18A or 18B is pressed and moved outward against the urging force of the elastic body 21A or 21B, and moves outward from the knob-shaped position detecting member 18A or 18B. Is constant, that is, when the piston 14 reaches the stroke end, the operating piece 22a of the limit switch 22A or the operating piece 22b of the limit switch 22B is operated as shown by the solid line in FIG. By the operation signal, the supply / discharge control operation of the pressurized fluid into the cylinder body 13 and the operation of the cylinder C are performed. Locked, the valve body is fixed and held in the fully open position or fully closed position.

As described above, the limit switches 22A and 22B are operated via the knob-shaped position detecting members 18A and 18B which are arranged at both ends in the axial direction of the cylinder body 13 and are directly linked to the movement of the piston 14. Therefore, unlike the case where the limit switch is operated through the movement of the piston rod or the guide rod, the limit switches 22A and 22B do not need to be installed with a space equal to the stroke. The overall length of the device or device on which the device is mounted can be reduced.

In the above-described embodiment, the position detection function is realized by operating the limit switches 22A and 22B by moving the two knob-shaped position detection members 18A and 18B. It is also possible to color the outer end portions of the shape position detecting members 18A and 18B or to display "end", and detect the position by looking at it with the naked eye.

[0016]

As described above, according to the present invention, the two knob-shaped position detecting members supported at both axial ends of the cylinder body are directly linked to the reciprocating motion of the piston in the position detecting direction. By moving the cylinder and detecting the movement of the knob-shaped position detecting member, both stroke ends (two positions) of the cylinder can be detected. Therefore, there is no need to provide a space equal to the full stroke of the cylinder for position detection, and the cylinder itself can be shortened in length, and the length of the device and equipment on which the cylinder is mounted is also shortened to save space, and Can be installed and used economically.

[Brief description of the drawings]

FIG. 1 is an external side view of an entire cylinder with a position detecting device according to the present invention.

FIG. 2 is an enlarged vertical sectional side view of the cylinder.

FIG. 3 is an enlarged vertical sectional side view of a main part of the cylinder.

FIG. 4 is an external side view of a conventional cylinder with a position detecting device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Head cover 12 Rod cover 13 Cylinder main body 14 Piston 15 Piston rod 18A, 18B Knob-shaped position detecting member 21A, 21B Elastic body 22A, 22B Limit switch

Claims (1)

[Claims] 1. A cylinder having a piston fitted and held in a cylinder body so as to be reciprocally movable in an axial direction, and a piston rod for operating a driven body connected to the piston, wherein both ends of the cylinder body in the axial direction are provided. Each of the portions has a knob-shaped position detecting member movably supported in a direction parallel to the reciprocating direction of the piston, and both of the knob-shaped position detecting members are normally urged to move such that one end thereof protrudes into the cylinder body. When the piston reaches near the end in the reciprocating direction, the piston comes into contact with one end of the knob-shaped position detecting member, and the knob-shaped position detecting member is pressed against the urging force of the elastic body. A cylinder with a position detecting device, which is configured to be pressed and moved in a position detecting direction.