JPH0222483Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field] The present invention relates to an actuator piston position detection device, and in particular, it detects the actuator's operation by detecting the position of a magnet that is moved together with a moving member such as a reciprocating rack. The present invention relates to a piston position detection device that allows the situation to be grasped from the outside.

[Background technology]

2. Description of the Related Art As an actuator for machine tools and various automatic working machines, there is, for example, a rack and pinion type rotary actuator.

In other words, compressed air pressure is applied to a piston formed at the end of the rack to cause it to reciprocate, and the pinion meshed with the rack converts it into torque for a shaft, etc., which drives a predetermined external load. It is configured to do so.

In such a rotary actuator, the direction and amount of rotation of the shaft or the amount and direction of movement of the piston or rack are detected, and based on the detection results, the operation of the rotary actuator itself is controlled or the external load is controlled. It may be necessary to control the amount of movement, etc., and for this purpose a piston position detection device may be provided.

This piston position detection device can detect the position of a moving member such as a rack by providing a ring-shaped magnet on a moving member such as a rack or a piston, and providing a magnetic sensor that is sensitive to the magnet outside the cylinder. It is conceivable to configure the system so that it can be understood from the outside.

However, in the piston position detection device as described above, the magnetic sensor is provided on a part of the outer circumference of the cylinder, whereas the magnet is provided in a ring shape around the entire circumference of the rod or piston.
This magnet also occupies space other than that required for sensing the magnetic sensor.

For this reason, there is a problem that the shape of the cylinder in which the moving member is housed becomes large, and furthermore, the shape of the entire actuator becomes larger than necessary.

Furthermore, in order to detect the two moving ends of the rack, conventionally two ring-shaped magnets were installed at both ends of the rod, and the positions of these magnets were detected by magnetic sensors installed at each end of the cylinder. There was a problem in that the axial dimensions of the rack and cylinder became long.

[Purpose of invention]

An object of the present invention is to provide a piston position detection device that can be miniaturized.

Another object of the present invention is to provide a piston position detection device that can reduce the size of an actuator to which it is attached.

[Summary of the idea]

In the present invention, an actuator piston position detection device that detects the stroke amount of a moving member that is reciprocated within a cylinder by fluid pressure is provided in the axial direction at a position eccentric from the axis of the moving member's cylinder. The piston position detection device itself can be miniaturized by comprising a magnet embedded in a hole and a magnetic sensor placed on the outer periphery of the cylinder at a position corresponding to the stroke end of the magnet. At the same time, the space occupied by the magnet inside the moving member, that is, inside the cylinder, is greatly reduced, and by detecting the short stroke of a single magnet, the reciprocating position of the moving member can be grasped. The actuator to which the detection device is attached can be made smaller.

〔Example〕

FIG. 1 is a sectional view showing the installed state of a piston position detection device for a rotary actuator which is an embodiment of the present invention, and FIG. 2 is an external plan view thereof;
Fig. 3 is a side view seen from the direction indicated by the line - in Fig. 1, and Fig. 4 is a side view seen from the direction indicated by the line - in Fig. 1.
FIG.

Inside the main body 1, cylinders 2 and 3 having parallel axes in the same plane are formed, and a pinion 4 is provided perpendicularly to the plane and penetrating the boundary between the cylinders 2 and 3.

A pair of bearings 5 that are fitted into the main body 1 are provided at both ends of the pinion 4, and the pinion 4 is rotatably supported.

Furthermore, a main shaft 6 (shaft body) coaxial with the pinion 4 is formed at one end of the pinion 4 so as to protrude to the outside of the main body 1 .

The teeth of this pinion 4 are exposed inside the cylinders 2 and 3 provided in parallel, and are linearly attached to the side surfaces of cylindrical members housed in the cylinders 2 and 3 so as to be movable in the axial direction. It has a structure in which it is simultaneously engaged with a pair of racks 7 and 8 (moving members) formed by forming teeth.

Furthermore, at one end of the pair of racks 7 and 8,
Pistons 9 and 10 are formed respectively, and two fluid chambers are independently constructed together with a cylinder cover 11 that closes one end of the cylinders 2 and 3.

Around the pistons 9 and 10 are piston gaskets 12, and around the cylinders 2 and 3, respectively.
O-rings 13 are installed between the cylinder cover 11 and the cylinder cover 11 to maintain airtightness of the two fluid chambers.

Then, by applying, for example, compressed air pressure (fluid pressure) to the two fluid chambers alternately through pressure ports 14 and 15 formed in the cylinder cover 11 and communicating with the two fluid chambers individually. , the rack 7 or 8 is linearly reciprocated, and a predetermined swing torque is generated on the main shaft 6 via the pinion 4.

In this case, a horizontal hole is formed in the rack 7 in a direction perpendicular to the paper surface of FIG. It is configured to be mounted inside the rack 7, fixed by a stopper 16, and moved together with the rack 7.

On the other hand, on the external wall surface of the main body 1 on the side of the cylinder 2, a pair of magnetic sensors S1 and S2 that are sensitive to the magnetism of the magnet M are installed at positions corresponding to the stroke ends of the magnet M that reciprocates with the rack 7. It is fixedly disposed by a holder 17 and a screw 18, and is connected to a predetermined control device via cables 19 and 20 when the magnet M is located directly below the wall surface of the main body 1. By transmitting electrical signals, etc., the positions of the racks 7 and 8, the rotation angle of the pinion 4, that is, the main shaft 6, etc. can be grasped from the outside.
A piston position detection device is configured.

These magnetic sensors S1 and S2 are, for example,
It consists of a reed switch that opens and closes depending on the presence or absence of magnetic action.

As described above, in the piston position detection device of this embodiment, one magnet M is mounted at an eccentric position inside one of the racks 7, so that the magnet M occupies the external space of the rack 7. Moreover, since the teeth of the rack 7 and the magnet M mounted inside the rack 7 do not interfere with each other, there is no need to increase the diameter of the rack 7.

As a result, the rotary actuator to which the piston position detection device is mounted can be downsized.

Furthermore, since the position of the rack 7 within the cylinder 2 can be determined by detecting the relatively short stroke of one magnet M mounted inside the rack 7, It becomes possible to provide the magnetic sensors S1 and S2 close to each other, the length of the cylinder 2, that is, the main body 1 of the rotary actuator can be shortened, and the rotary actuator is made smaller.

Further, a dustproof cover 21 is provided at a position facing the cylinder cover 11, and
It is configured to prevent dust, foreign matter, etc. from entering the inside.

The operation of this embodiment will be explained below.

First, compressed air is introduced into the cylinder 3 through, for example, the pressure port 15, and air pressure is applied to the piston 10 formed at the end of the rack 8, so that the rack 8 is moved to the left in FIG.

At this time, the pinion 4 meshed with the rack 8 receives rotational force due to the movement of the rack 8, and a predetermined torque is generated on the main shaft 6, which is formed coaxially and integrally with the pinion 4, and is connected to the main shaft 6. A predetermined load (not shown) is driven.

On the other hand, the rack 7 which is engaged with the pinion 4 together with the rack 8 is driven in the opposite direction to the rack 8 via the pinion 4, and a piston 9 formed at the end thereof is driven.
is stopped at the position where it comes into contact with the cylinder cover 11, that is, at the stroke end, and the movement of the rack 8 is also stopped at the same time by the reaction force acting on the rack 7.

Furthermore, the magnet M installed inside the rack 7 senses the magnetic sensor S2 installed outside the cylinder 2, which corresponds directly above the magnet M, and sends a predetermined electrical signal to the control equipment etc. through the cable 20. is transmitted, it is recognized that the rack 7 is located at the stroke end on the cylinder cover 11 side, and a predetermined control operation, such as canceling the action of air pressure on the pressure port 15, is performed.

Similarly, when air pressure is applied to the pressure port 14, the rack 7 is moved to the stroke end on the side of the dustproof cover 21, and the piston 10 of the rack 8, which is driven via the pinion 4, comes into contact with the cylinder cover 11. The magnet M installed in the rack 7 is stopped at the position where it touches the magnetic sensor S.
1 is sensed, and it is understood that the rack 7 is located at the stroke end on the dustproof cover 21 side.

In this way, by detecting the position of the rack 7 on which the magnet M is attached, it is possible to accurately grasp the operating conditions such as the amount of rocking of the pinion 4 meshed with this rack 7, and it is possible to accurately grasp the operating status such as the amount of swing of the pinion 4 that is engaged with the rack 7. The movement of the load driven by the main shaft 6 is precisely controlled.

Although the present invention has been specifically explained above based on the examples, it goes without saying that the present invention is not limited to the above-mentioned examples and can be modified in various ways without departing from the gist thereof.

For example, the fluid for driving the racks 7 and 8 is not limited to compressed air, but may also be pressurized oil.

The cross-sectional shape of the magnet can also be arbitrary, such as circular, square, or other polygonal shapes.

Furthermore, magnetic sensors and magnets may be provided separately on both sides of the cylinder corresponding to each rack, as shown by the two-dot chain line in Figure 1, making it easy to detect the piston position even when the piston stroke is short. There is also the advantage that the lead wires can be wired in the same direction for both sensors.

〔effect〕

(1) The piston position detection device uses a magnet embedded in a hole provided in the axial direction of the cylinder at a position eccentric from the axis of the cylinder of a moving member that is moved within the cylinder, and the movement of the outer circumference of the cylinder. It consists of a magnetic sensor that is placed at a position corresponding to the stroke end of the member and is sensitive to a magnet held eccentrically inside the moving member.
The piston position detection device is miniaturized.

(2) As a result of (1) above, the magnet does not occupy the external space of the rack, and the teeth of the rack and the magnet installed inside the rack do not interfere, so the actuator to which the piston position detection device is installed is The rack and cylinder can be made smaller in diameter.

(3) As a result of (1) above, the position of the rack inside the cylinder can be accurately determined by detecting the short stroke of the magnet installed inside the rack. It becomes possible to provide a magnetic sensor close to the cylinder, ie, the length of the actuator body.

(4) As a result of (2) and (3) above, the entire actuator to which the piston position detection device is attached can be downsized.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing the installed state of a piston position detection device of a rotary actuator which is an embodiment of the present invention, Fig. 2 is an external plan view thereof, and Fig. 3 is indicated by a line - in Fig. 1. FIG. 4 is a sectional view of the portion indicated by the line - in FIG. 1. 1...Body, 2, 3...Cylinder, 4...Pinion,
5...Bearing, 6...Main shaft (shaft body), 7, 8...Rack,
9, 10...Piston, 11...Cylinder cover, 1
2...Piston seal, 13...O ring, 14,
15...Pressure port, 16...Plug, 17...Sensor holder, 18...Screw, 19, 20...Cable, 21...
Dust cover, M...Magnet, S1, S2...Magnetic sensor.

Claims (1)

[Claims for Utility Model Registration] 1. An actuator that extracts reciprocating motion within a cylinder of a movable member driven by fluid pressure as torque of a shaft body, wherein the cylinder of a movable member that is moved within the cylinder a magnet embedded in a hole provided in the axial direction of the cylinder at a position eccentrically outward from the axis of the cylinder;
A piston position detecting device for an actuator, comprising: a magnetic sensor that is disposed on the outer periphery of the cylinder at a position corresponding to a stroke end of the moving member and that is sensitive to the magnet. 2. A piston position detection device for an actuator according to claim 1, wherein the moving member is a rack having a piston disposed at an end thereof. 3. The actuator piston according to claim 1, wherein the actuator is a rack and pinion type rotary actuator that obtains the torque of the shaft body through a pinion meshed with a reciprocating rack. Position detection device.