JPS5854648Y2 - Position sensing device for fluid pressure cylinders - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a position detection device for a fluid pressure cylinder, and more specifically, it is used to detect the position of a magnetic piston reciprocating within a fluid pressure cylinder having a cylinder made of a non-magnetic material. The present invention relates to a suitable position sensing device.

Hereinafter, one embodiment of the present invention will be explained with reference to the drawings.
The figure shows a position sensing device 20 according to the present invention attached to a fluid pressure cylinder 1.
In this fluid pressure cylinder 10, a magnetic piston 12 is reciprocatably fitted inside a cylinder 11 formed of a non-magnetic material such as an aluminum alloy or a synthetic resin material. ing.

The position detection device 20 is constructed by arranging magnets 23 and 24 parallel to each other as shown in FIGS. 2 and 3, and interposing a reed switch 25 between the pair of magnets 23 and 24. In this position detection device 20, as is clear from FIG. 4, a series circuit consisting of a neon lamp 26 and a resistor 27 is connected in parallel to a normally open reed switch 25, It is fixed together with a synthetic resin 28 and housed inside a casing 21 made of a magnetic material.

Further, in this case, the neon lamp 26 is embedded in the casing 21 with the synthetic resin 28 so that its blinking can be visually observed from outside the elongated hole 22 provided in the casing 21.

In particular, in this position detection device 20, the N poles of the pair of magnets 23 and 24 are both located at the bottom of the casing 21, and the S poles are located at the top (that is, the magnetization polar directions of both magnets are in the same direction). ) X arrangement such that both magnetic lines of force of these magnets 23 and 24, that is, both magnetic fluxes...
In an equilibrium state in which the magnetic pistons repel each other, they penetrate deeply into the cylinder 11 perpendicular to the reciprocating direction of the magnetic piston 12.

In other words, when both the magnetic fluxes of the magnets 23 and 24 are in an equilibrium state, as can be easily understood from the virtual lines shown in FIGS. 5 and 6, part of the magnetic flux generated from the magnets 23 and 24 enters the casing 21, and the remaining portions of both magnetic fluxes repel each other and penetrate deeply into the cylinder 11.

Therefore, there is little magnetic flux entering the reed switch 25 from both magnets 23 and 24 in its width direction, and therefore, even if both contact pieces constituting the reed switch 25 are magnetized in their width and thickness directions, this The magnetizing force does not reach a value that closes both contact pieces of the reed switch 25 in the open state against its elasticity.

Furthermore, even if some magnetic flux enters the reed switch 25 from both magnets 23 and 24 in its longitudinal direction, this magnetizing force is It acts to maintain the leaderch 25 in an open state.

Therefore, in the position detection device 20 configured as described above, when the magnetic piston 12 of the fluid pressure cylinder 10 slides to the left in FIG. , the equilibrium state of some of the magnetic fluxes of the magnets 23, 24 is disturbed, and the magnets 23.
Both magnetic fluxes from 24 penetrate the right arm of the node switch 25 in its longitudinal direction, enter the magnetic piston 12, and then return to the magnets 23 and 24 (see FIG. 7).

As a result, the right contact piece of the reed switch 25 is strongly magnetized in the longitudinal direction, and its inner end increases its magnetizing force as an S pole.

Thus, in the reed switch 25, the inner end of the left armature, which was weakly magnetized as an S pole, is magnetized as an N pole under the action of the strong magnetizing force of the inner end of the right armature as an S pole, and the reed switch Both contact pieces 25 close against their elasticity, and the neon lamp 26 becomes clear.

Therefore, in this position detection device 20, the position of the magnetic piston 12 can be detected with high sensitivity in a stable state by blinking the neon lamp 26, and the operating state of the reed switch 25 can also be confirmed. can.

Further, as described above, the reed switch 25 is connected to the magnet 2.
3.24, so even if the amount of both magnetic fluxes decreases due to an increase in ambient temperature, the change in the amount of magnetic flux acting on the reed switch 25 is very small, and the As a result, the detection sensitivity of the device of the present invention does not decrease.

In the above embodiment, an example was described in which the pair of magnets 23 and 24 were arranged such that their N poles were both located at the lower part of the casing 21, but these magnets 23.
24 may be arranged so that both S poles are located at the lower part of the casing 21.Also, in the above embodiment, an example was explained in which a neon lamp 26 was connected in parallel to the reed switch 25. It is clear that the semiconductor light emitting device may be connected in series with the reed switch 25 in this case.

Furthermore, in carrying out the present invention, both the magnets 23 and 24 may be arranged so as to be inclined to each other so that the distance between them becomes narrower as the distance approaches the outer circumference of the cylinder 11. As understood, the magnet 23
．． The magnetic flux entering the cylinder 11 from 24 is further increased, and the detection sensitivity and stability of the device of the present invention can be further improved.

Furthermore, in this case, by adjusting the position of the reed switch 25 relative to the magnets 23, 24 somewhat in the direction of the reciprocating movement of the magnetic piston 12, the detection characteristics of the device according to the invention can be adjusted as required.

In summary, in the present invention, as shown in the above embodiment, a pair of magnets are placed in a casing made of a magnetic material attached to the outer periphery of a cylinder made of a non-magnetic material, and the magnetization polarity direction of the pair is Both are arranged in the same direction so as to be substantially perpendicular to the reciprocating direction of the magnetic piston, and are arranged on the outer periphery of the cylinder so as to be substantially parallel to the reciprocating direction of the magnetic piston or a direction perpendicular thereto. and a normally open type reed switch that closes when the magnetic piston is located within the magnetic flux area of both the magnets is disposed between the two magnets, and both the magnets and the normally open type reed switch are respectively attached to the casing using synthetic resin. Its structural feature lies in that it is fixed at each of the above-mentioned positions within the cylinder, and as a result, each magnetic flux that penetrates deeply into the cylinder in a state of mutual repulsion from both magnetic fields is It acts effectively on the magnetic piston and the reed switch, and as a result, the operating sensitivity and stability of the reed switch are significantly improved.

In addition, in the present invention, if the piston that reciprocates within the cylinder is a magnetic piston made of iron or the like, the reed switch can be opened and closed without any processing on the piston. It has the advantage of being easily applicable to fluid pressure cylinders.

In addition, in the present invention, when both the magnets are arranged on the same plane at the outer circumference of the cylinder, the outer shape of the casing can be formed as flat and compact as possible, making it easy to attach it to the fluid pressure cylinder. You can get used to it.

[Brief explanation of drawings]

Fig. 1 is a front view with a main part cut away showing the position detection device according to the present invention installed on the outside of a fluid pressure synonda, Fig. 2 is a partially cutaway plan view of the same position detection device, and Fig. 3 is the same as in Fig. 2. 1-
4 is a cross-sectional view taken along line 1, FIG. 4 is an electric circuit configuration diagram of the position detection device shown in FIG. 1, and FIGS. 5 and 6 are respectively,
FIG. 3 and FIG. 1 are diagrams showing the balanced state of the magnetic flux distribution in the position detection device using imaginary lines, and FIG. 7 is a diagram showing the disturbed state of the magnetic flux distribution in FIG. 6 using imaginary lines. Explanation of symbols 10...Fluid pressure cylinder, 11.
...Cylinder, 12...Magnetic piston,
20...Position detection device, 21...Casing, 22...Elongated hole, 23.24...
・Magnet, 25... Reed switch, 28...
...Synthetic resin.

Claims (1)

[Scope of utility model registration request] In a fluid pressure cylinder in which a magnetic piston is fitted into a cylinder made of a non-magnetic material so as to be able to reciprocate in the axial direction, a pair of magnets are magnetized in a casing made of a magnetic material attached to the outer periphery of the cylinder. The cylinders are arranged so that their polar directions are the same and are substantially perpendicular to the reciprocating direction of the magnetic piston, and the cylinders are provided on the outer periphery of the cylinder so as to be substantially parallel to the reciprocating direction of the magnetic piston or a direction perpendicular thereto. A normally open reed switch that closes when the magnetic piston is located within the magnetic flux area of both magnets is disposed between both magnets, and both magnets and the normally open reed switch A position detection device for a fluid pressure cylinder fixed at each of the above-mentioned positions with synthetic resin inside the casing.