JPH0734326Y2 - Piston position detection mechanism - Google Patents

Description

[Detailed description of the device]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piston position detecting mechanism, and more specifically, a sensor for detecting the position of a piston in a cylinder forming a fluid pressure circuit is provided with a magnetic field of a magnetic substance fixed to the piston. The present invention relates to a piston position detection mechanism attached to a position where strength is maximized.

[0002]

2. Description of the Related Art Conventionally, when an article is conveyed using a fluid pressure cylinder to perform a predetermined work, it is necessary to determine whether or not a piston reciprocating in the cylinder has reached a predetermined position in the cylinder. It is necessary to confirm. Therefore, the cylinder is fixed at the predetermined position by using a magnetoresistive element whose electric resistance changes according to the strength of the magnetic field, while
By embedding a permanent magnet in the piston, when the piston reciprocates and passes through the predetermined position, the position of the piston is detected by the resistance change of the magnetoresistive element.

3 and 4 show a cylinder provided with a piston position detecting device according to the prior art. The position detection device 2 mounted on this cylinder basically includes a magnetic field detection circuit unit 4 and a piston position detection unit (for example, a sequencer) 6. A magnetic body 12 containing magnetic powder is embedded in an annular shape in a piston 10 that reciprocates in the cylinder 8, and the magnetic body 12 and the magnetic field detection circuit unit 4 are within a certain distance, that is, the piston 10 has a detection range. When it is in F, the position detecting device 2 can determine that the piston 10 is at a predetermined position or is performing a normal reciprocating operation.

In this case, in the above-mentioned prior art, the groove 1 formed on the outer side portion of the cylinder 8 in relation to the position detecting device 2
A bulging portion 14 is formed in the center of the bulge 1 so as to extend in the axial direction, and the bulging portion 14 extends in the longitudinal direction to define a mounting groove 16. Then, the nut 18 is fitted into a desired position of the mounting groove 16, the mounting member 20 is stacked on the nut 18, and the bolt 22 and the nut 24 are tightened. The magnetic field detection circuit unit 4 is integrally fixed to the mounting member 20.

[0005]

However, in the above-mentioned prior art, the mounting groove 1 bulged on the outer surface of the cylinder.
Since 6 is disposed substantially in the center of the groove 11, the position of the sensor 26 as a magnetoresistive element incorporated in the magnetic field detection circuit unit 4 is deviated. That is, this may cause the position of the sensor 26 to deviate from the position showing the maximum magnetic field strength, and the position of the piston 10 may not be detected well. In other words, as shown in FIG. 4, when the position of the sensor 26 of the magnetic field detection circuit unit 4 deviates from the strongest magnetic field, the strength of the magnetic field reaching the sensor 26 decreases even if the piston 10 reciprocates. It becomes difficult for the magnetic field detection circuit unit 4 to detect the position of the piston 10.

The present invention has been made in order to overcome the above-mentioned inconvenience, and detects the maximum magnetic field of a magnetic body fixed to a piston at an arbitrary position along the longitudinal direction of the cylinder with a magnetic field detection circuit section. It is an object of the present invention to provide a piston position detection mechanism that can be attached to a position where the piston position is detected, and thereby can accurately detect the piston position.

[0007]

In order to achieve the above object, the present invention comprises a cylinder body having a substantially rectangular cross section.
A fixer with a circular cross section that reciprocates in a fluid pressure cylinder.
On the outer wall of the cylinder body
A mounting groove that extends along the axial direction and is displaced from the central portion
A mounting member but which is defined, is attached to the attachment groove, wherein
The magnetic field strength of the magnetic body is formed integrally with the mounting member.
With a magnetic sensor that detects the position of the piston
And a magnetic field detecting section for mounting the mounting member in the mounting groove.
The magnetic sensor is attached to the cylinder body
It is characterized in that it is positioned and arranged at a portion where the wall thickness is the thinnest .

[0008]

In the piston position detecting mechanism according to the present invention, it is possible to dispose a mounting member which is located outside the cylinder and which is suitable for detecting the maximum magnetic field of the magnetic material embedded in the piston. As a result, it is possible to accurately detect the position of the piston or confirm whether the reciprocating motion has been accomplished.

[0009]

【Example】

A preferred embodiment of the piston position detecting mechanism according to the present invention will be described below in detail with reference to the accompanying drawings.

In FIG. 1, reference numeral 30 indicates a piston position detecting mechanism according to the present invention. The piston position detecting mechanism 30 defines recesses 32a, 32b, and 32c that expand outward in the central portion in the longitudinal direction of a cylinder 32 having a rectangular cross section. Incidentally, these recesses 32b,
Since 32c has substantially the same shape as the recess 32a, the recess 32a will be described in detail below.

A step portion 34 is bulged at one corner of the recess 32a, and a groove 36 (mounting groove) is defined in the step portion 34 so as to extend in the longitudinal direction of the cylinder 32. The groove 36 is
As shown in FIG. 1, it is slightly deviated from the center of the recess 32a. A nut 38 is fitted in a predetermined position of the groove 36,
The tip of a bolt 40 is screwed onto this nut 38, and a mounting member 42 is fitted into this. The mounting member 42 is integral with the magnetic field detection unit 44, and the magnetic field detection unit 44 includes a magnetic sensor 48 at the bottom of a housing that incorporates a detection circuit (not shown). A nut 50 is screwed onto the mounting member 42, and the mounting member 42 is firmly fixed via a washer 53. With this structure, the magnetic sensor 48 is located at the center of the recess 32a and the cylinder 32.
Thickest thin site (maximum thin site), i.e., the magnetic field strength closest to the magnetic body 54 to be fitted to the piston 52 of
It will be readily appreciated that it will be positioned and placed at the site of greatest degree .

Since the recesses 32b and 32c are also formed with steps and grooves, the magnetic field detector 44 can be selectively positioned in any of the recesses 32a to 32c.
Here, in FIG. 2, reference numerals 56 a and 56 b indicate ports for supplying the pressure fluid to the cylinder 32.

Therefore, the operation of the piston position detecting mechanism constructed as described above will be described.

First, the pressure fluid is alternately supplied from the ports 56a and 56b through the pressure fluid pipeline (not shown) to the cylinder 32.
When introduced therein, the piston 52 performs a displacement operation. At this time, the ring-shaped magnetic body 54 fitted to the piston 52 slides inside the cylinder 32 made of a non-magnetic body together with the piston 52, and the magnetic field of the magnetic body 54 is detected by the magnetic field detector 44. Of the magnetic sensor 48. The magnetic sensor 48 is provided in the cylinder 32 as described above.
Since it is fixed to the thinnest portion, that is, to the portion of the cylinder 32 that is closest to the maximum magnetic field position detection position in the radial direction, the sliding displacement of the piston 52 can be easily detected. Therefore, according to the present embodiment, it is possible to accurately detect the position of the piston 52. From this, even when the magnetic body 54 that generates an extremely weak magnetic field line is attached to the piston 52, the magnetic field It is possible to easily detect the presence or absence of and confirm the piston position. Moreover, if the cylinder 32 itself also employs the above-described structure, it is possible to obtain an effect that the drawing or extrusion molding becomes easier than the conventional one and the material cost is reduced.

[0015]

As described above, according to the present invention, the magnetic sensor for detecting the piston position is mounted at the position where the magnetic flux of the magnetic body mounted on the piston is maximum. The position of the piston can be detected extremely easily, and it is possible to reduce the size of the magnetic body itself attached to the piston when trying to detect the piston position with the same magnetic field line as compared to the conventional piston position detection device. The effect is obtained.

[Brief description of drawings]

FIG. 1 is a sectional view of an embodiment of a piston position detection mechanism and a cylinder according to the present invention.

FIG. 2 is a perspective explanatory view of a piston position detection mechanism and a cylinder shown in FIG.

FIG. 3 is a vertical cross-sectional explanatory view of a piston position detecting device according to a conventional technique.

FIG. 4 is an explanatory view of a vertical section of mounting of a piston position detecting device according to a conventional technique.

[Explanation of symbols]

 30 ... Piston position detecting mechanism 32 ... Cylinder 34 ... Step portion 42 ... Mounting member 48 ... Magnetic sensor

Claims (1)

[Scope of utility model registration request] 1. A fluid comprising a cylinder body having a substantially rectangular cross section.
A piston with a roughly circular cross section that reciprocates in the pressure cylinder
The magnetic body to be mounted and the outer wall surface of the cylinder body are extended along the axial direction and
The mounting groove that deviates from the center is defined in the mounting groove.
A mounting member to be attached and a magnetic field of the magnetic body formed integrally with the mounting member.
Magnetic sensor for detecting the position of the piston by strength
And a magnetic field detector having, by mounting the mounting member in the mounting groove,
The magnetic sensor has the thinnest wall thickness of the cylinder body.
A piston position detecting mechanism characterized in that it is positioned and arranged in a different area.