JPH04515Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] The present invention relates to a magnetic material detection switch among proximity switches that operate using a reed switch, and is capable of widening the detection area width. This is how it was done.

[Conventional technology]

As is well known, among the proximity switches that operate using a reed switch, a magnetic body detection switch has a configuration in which the reed switch and a permanent magnet are moved relative to each other, and a permanent magnet is assembled and fixed to the reed switch. There is a configuration that changes the magnetic flux distribution of the permanent magnet by moving a sensing object made of a magnetic material into the magnetic field formed by the permanent magnet, which changes the magnetic field acting on the reed switch. This is intended to turn on and off (for example, Japanese Utility Model Publication No. 53-34636).

Since it is convenient in terms of operation and handling that the reed switch and the permanent magnet are integrated, the latter magnetic substance detection switch described above is generally widely adopted.

However, in the case of the latter type of magnetic material detection switch, the operating magnetic field region of the reed switch formed by the permanent magnet is relatively gentle in many parts along the moving direction of the detected object. Due to the hysteresis characteristic of the response, there is a drawback that the response difference due to the difference in the moving direction of the detected object becomes large.

In addition, most of the latter magnetic body detection switches that are commonly used are of the magnetic shield type, and therefore, the magnetic flux applied to the reed switch is reduced by the shield plate or shield case. There is also the disadvantage that sensitivity is reduced.

An invention such as Japanese Patent Application No. 198567-1983 has been proposed as a magnetic material detection switch that solves these problems.

In the above invention, as shown in FIGS. 5 and 6, a pair of bias magnets 2 are attached to one magnetic pole surface of a permanent magnet 1.
is attracted with the magnetic pole faces facing each other, and the reed switch 3 is placed between the pair of bias magnets 2, which reduces the variation in left and right hysteresis compared to conventional products. Since the pair of bias magnets 2 are arranged so as to be attracted to the permanent magnet 1, it is easy to adjust the mutual assembly of the permanent magnet 1 and the bias magnet 2. By attaching a shield case or the like, the influence of external magnetic fields can be reduced, which has produced excellent effects.

[Problem that the invention attempts to solve]

However, according to actual measurements, the above invention is
The operating magnetic field region is drawn in the form shown in the figure, and therefore, as is clear from FIG. However, in reality, due to the thickness of the outer case and the clearance for installation space, the above distance is a little longer than h1, and the conventional In this case, the operating region l1 is short, leaving concerns about reliable detection.

That is, in the state of this operating region l1, when the detected object 4 moves at high speed, the output time width of the detection signal of the reed switch 3 becomes short, so the reed switch 3 is used to control the relay, etc. When attempting to drive a load that requires a response time longer than 100 hrs., the output time of the detection signal from the reed switch 3 becomes shorter than the response time of this load.
This resulted in the inconvenience that the load would not operate even though the reed switch 3 outputs a detection signal.

That is, if the distance from the detected object 4 is h2 in FIG. 6, the operating region width l2 will be long, so the output time of the detection signal of the reed switch 3 can be lengthened without any problem. If the above-mentioned interval is h1, the operating region width l1 is short, so when the detected object 4 moves at high speed, the output time of the detection signal of the reed switch 3 becomes short, and there is a drawback that the load cannot be driven. It is.

In the case of the prior art shown in FIGS. 5 and 6,
Since the bias magnet 2 is attached to the permanent magnet 1 in a position that increases the magnetic force on the reed switch 3, the operating range of the reed switch 3 is widened, and the attachment position of the bias magnet 2 with respect to the permanent magnet 1 can be adjusted. , since it is shifted to one side (left side) from the center of the permanent magnet 1, the operating area of the enlarged reed switch 3 does not expand symmetrically with respect to the center of the permanent magnet 1, but is biased to one side. By enlarging it, it is possible to obtain a large operating area with a large operating area width l.

However, the expansion of the operating range in the above conventional technology is obtained by applying the magnetic force of the bias magnet 2 to the permanent magnet 1, and the magnetic force of the bias magnet 2 is biased toward one side of the permanent magnet 1. Therefore, bias magnet 2
Since it also works to attract the magnetic force on the other side of the permanent magnet 1 to one side, the expanded operating area becomes such that one side of the permanent magnet 1 is extremely larger than the other side. .

The present invention was devised to solve the problems, drawbacks, and inconveniences of the conventional examples described above.
The purpose of this is to lengthen the detection area and make the detection area almost flat.

[Means and actions for solving problems]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A magnetic substance detection switch according to the present invention will be described below with reference to drawings showing an embodiment of the present invention.

The magnetic substance detection switch according to the present invention has a pair of bias magnets 2 placed at both ends of one magnetic pole surface of a permanent magnet 1 with their respective magnetic pole surfaces facing the above-mentioned one magnetic pole surface at a constant interval. The side of each bias magnet 2 that is attached to the above-mentioned permanent magnet 1 at one end is the S pole, and the opposite side is the N pole. The bias magnet 2 is constructed so that the polarity of the bias magnet 2 is different between one end and the other end, with the side facing the bias magnet 2 being an N pole and the opposite side being an S pole.

Further, a reed switch 3 is disposed between the pair of bias magnets 2 described above, and the reed switch 3 is arranged along the magnetic pole of the permanent magnet 1 from one end to the other end of the single bias magnet 2 described above. The posture is perpendicular to the direction.

As a result, according to actual measurements, the detection area here takes the form shown in Fig. 2 and can be made almost flat, and the operating area width is
As shown in the figure, the distance to the detected object 4 is h1 and h2.
This results in l1 and l2 with almost no difference.

That is, in a state where the detected object 4 is not approaching, the magnetic force acting on the reed switch 3 is equal to the magnetic force acting between the permanent magnet 1 and the bias magnet 2;
The magnetic force acting between both magnetic poles of bias magnet 2 is
Since these two magnetic forces act in opposite directions, they cancel each other out, so that the reed switch 3 is turned off. When the detected object 4 enters the operating area from this state, the magnetic force acting mainly between the permanent magnet 1 and the bias magnet 2 is attracted to the detected object 4. Only the magnetic force acting between the two magnetic poles acts strongly, thereby turning the reed switch 3 on.

In this way, the on/off operation of the reed switch 3 causes the magnetic force of the permanent magnet 1 and the magnetic force of the bias magnet 2 to repel, and the balance of this repulsion is adjusted to the detected object 4.
Since the ON operation of the reed switch 3 is achieved by the magnetic force of the bias magnet 2, the operating area formed is the same as that of the permanent magnet 1, as shown in FIG. In the interval h distance range in which the magnetic force of the bias magnet 2, which has a weaker magnetic force than that, acts, the side where the bias magnet 2 is assembled with a bias toward the permanent magnet 1, that is, from this bias magnet 2 by the bias of the bias magnet 2. By being strongly subjected to the repulsive magnetic force of the permanent magnet 1, the magnetic force of the permanent magnet 1 is greatly biased toward the side where the magnetic force acting on the permanent magnet 1 is weaker.

In this way, if the operating region width l can be secured long, even if the detected object 4 moves at high speed in the h1 portion, the output time of the detection signal of the reed switch 3 can be lengthened. Even if the load requires a long response time, sufficient time can be secured to drive the load. Therefore, even if the load requires a certain amount of response time, such as a relay, can also be reliably driven by the magnetic proximity switch according to the present invention.

In addition, the width of the operating magnetic field region formed by the permanent magnet 1 and the pair of bias magnets 2 along the moving direction of the detected object 4, that is, the width of the operating magnetic field region, is slightly different in size from the reed switch 3. Even if there is a magnetic field, it remains almost constant with almost no change, so the mounting of the magnetic proximity switch of the present invention provides a constant operating magnetic field width l as long as the distance from the detected object 4 is within a certain range. As a result, it is possible to eliminate the instability of the detection operation in which the detection operation changes significantly due to a slight error in the mounting dimensions.

〔Example〕

FIG. 4 shows the configuration of an embodiment of the magnetic substance detection switch of the present invention, in which a combination of a permanent magnet 1 and a bias magnet 2 is immovably assembled and fixed in an assembly case 5. A reed switch 3 is embedded and fixed integrally with a combination of a permanent magnet 1 and a bias magnet 2 using a resin molding material 6, and furthermore, a magnetic shield against external magnetism is achieved on the outer surface of this assembly case 5. It is constructed by covering and fixing a shield case 7.

[Effect of idea]

As is clear from the above description, the present invention can increase the width of the detection area along the moving direction of the detected object, and the detection area that is formed can rise up with its width being approximately constant. In addition, the detection area is formed over the entire detection surface of the switch, so
Even if the relative movement speed with the detected object is high, the output time of the detection signal from the reed switch can be made sufficiently long, and the load can be reliably driven according to this detection signal. Since there is little hysteresis along the moving direction of the detected object, accurate sensing operation can be obtained.Furthermore, the size of the entire combination of magnet and reed switch can be reduced, so it can be constructed compactly. Even if there is some error in the installation dimensions, accurate operation can be obtained, making it easy to handle.
It exhibits many excellent effects.

[Brief explanation of the drawing]

FIG. 1 shows a magnetic substance detection switch according to the present invention, in which a is a front view, b is a side view, and c is a rear view. FIGS. 2 and 3 are actual measurement diagrams of the operating magnetic field area of the magnetic body detection switch according to the present invention. FIG. 4 is a sectional view showing an embodiment of the magnetic substance detection switch according to the present invention. FIGS. 5 and 6 are actual measurement diagrams of the operating magnetic field area of a conventional magnetic body detection switch. Explanation of symbols, 1...Permanent magnet, 2...Bias magnet, 3...Reed switch, 4...Detected object,
5... Assembly case, 6... Resin mold, 7...
shield case.

Claims (1)

[Scope of utility model registration request] At both ends of one magnetic pole surface of the permanent magnet 1,
A pair of bias magnets 2 with each magnetic pole face facing the one magnetic pole face are arranged at a constant interval, and each bias magnet 2 faces the permanent magnet 1 at one end. The side facing the permanent magnet 1 at the other end of each bias magnet 2 is the N pole, and the opposite side is the S pole, and further between the pair of bias magnets 2. A magnetic substance detection switch comprising a reed switch 3 disposed along the single bias magnet 2 from one end to the other end in a posture orthogonal to the magnetic pole direction of the permanent magnet 1.