JP4220790B2 - Magnetic detector - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a magnetic detector, and more particularly to an iron plate proximity type cylinder switch and an iron plate proximity type magnetic proximity switch.
[0002]
[Prior art]
As a proximity switch for detecting a magnetic material, an operation adjusting magnet or a magnetic material is provided so that the magnetic detection element is outside the operation limit with respect to the magnetic field of the magnet built in the proximity switch, or a plurality of magnets are used for magnetism. A method is known in which a detection element is placed outside the magnetic operating limit and a magnetic field exceeding the operating point is applied when the detection body approaches.
[0003]
[Problems to be solved by the invention]
As a proximity switch for detecting magnetic material according to the prior art, for example, in an iron plate proximity type cylinder switch, when a detected magnetic material (iron plate of the piston part inside the cylinder) is mounted on the outside of the cylinder tube, In this cylinder, the distance between the switch and the detection body is often 5 to 10 mm due to the influence of the wall pressure of the tube of the cylinder.
[0004]
For this reason, as shown in FIG. 6, for example, when using a reed switch 2001, a reed switch having a relatively low moving value (high sensitivity) is used as the magnetic detection element which is a main component of the switch. Used in combination with a magnet 2002 having a large magnetic force.
[0005]
At this time, when the magnet 2002 side is incorporated in a state close to the magnetic substance to be detected, the detection performance cannot be ensured, for example, the reed switch 2001 is always turned on. For this reason, each component configuration of the switch 200 with respect to the detected magnetic body is such that the reed switch 2001 and the operating point adjusting magnetic body from the side close to the detected magnetic body, that is, the side close to the BB surface as the detection surface. In general, 2003 and magnet 2002 were housed in case 2004 and sealed with mold resin 2005. That is, in order to reduce the influence of an external magnetic field and to maintain the position of each component, the reed switch 2001 and the operating point adjustment magnetism are detected from the detection surface side by an iron case 2004 that forms a magnetic path. The body 2003 and the magnet 2002 were wrapped and provided in this order.
[0006]
There are three problems in these configurations. First, since the reed switch of the magnetic detection element is arranged almost near the surface, there is anxiety in terms of strength. Since the surface side is closest to the tube of the cylinder when mounted on the cylinder, the protective material that protects the magnetic detection element in the structure where the magnetic detection element needs to be arranged on the surface side from the viewpoint of performance as described above. The thickness of (mold resin) must be thin.
[0007]
Secondly, in the conventionally used iron plate proximity type cylinder switch, the magnet as the magnetic source is not symmetrically arranged with respect to the reed switch which is a magnetic detection element. For this reason, intermediate detection is impossible, and its use is almost limited to end detection.
[0008]
Third, depending on the operating temperature range, the function of the switch may not be satisfied mainly due to the temperature coefficient of the magnet.
[0009]
The present invention has been made in consideration of the above circumstances, and even if the magnetic detection element uses a glass that is a brittle material such as a reed switch, the magnetic detection element is placed at a position where there is no fear of strength. As a cylinder switch, etc. that can be detected without hindrance when detecting not only the stroke end of the cylinder but also the middle point, and avoiding fluctuations in the operating characteristics of the low temperature side and high temperature side due to the temperature coefficient of the magnet An object of the present invention is to provide a magnetic substance detector that can be used.
[0010]
[Means for Solving the Problems]
In order to solve the above problem, in the present invention according to claim 1, a magnetic detection element;
A magnet for magnetically adjusting the magnetic detection element outside the operating limit in a normal state and applying a magnetic field exceeding the operating point when approaching a detected magnetic body to be detected;
The magnetism detection element and the magnet are accommodated in the case in the order of the magnet and the magnetism detection element from the side close to the detection surface facing the magnetic substance to be detected, and between the magnet and the magnetism detection element, There is provided a magnetic substance detector characterized in that a magnetic path member for attenuating magnetic force supplied from a magnet is interposed.
According to a second aspect of the present invention, in the magnetic substance detector according to the first aspect, the magnetic path member is interposed between at least opposing surfaces of the magnetic detection element and the magnet. A body detector is provided.
According to a third aspect of the present invention, in the magnetic substance detector according to the first aspect, the magnet has a magnetic pole axis direction substantially parallel to the operation direction of the detected magnetic body when the detected magnetic body is closest. Provided is a magnetic detector characterized by being arranged as follows.
According to a fourth aspect of the present invention, in the magnetic substance detector according to the first aspect, the magnet has a magnetic pole axis direction substantially equal to an operating direction of the detected magnetic body when the detected magnetic body is closest. Provided is a magnetic detector, which is arranged so as to be in an orthogonal direction.
According to a fifth aspect of the present invention, in the magnetic detector according to the first aspect, the magnets are composed of a set of two magnets, and the magnetic detection element is arranged from the center of the two magnets to the magnetic path member. There is provided a magnetic substance detector, which is magnetically arranged at substantially the same distance via the.
According to a sixth aspect of the present invention, in the magnetic substance detector according to the fifth aspect, two sets of auxiliary magnets are magnetically substantially equidistant from the magnetic detection element, and A magnetic material detector characterized in that an imaginary line connecting the centers of two auxiliary magnets is accommodated in a case in a positional relationship parallel to the imaginary line connecting the centers of the two magnets. I will provide a.
According to a seventh aspect of the present invention, in the magnetic substance detector according to the sixth aspect, magnets having the same temperature coefficient are selected as the magnets constituting the two sets of magnets, and the two sets of auxiliary devices are selected. While the magnets constituting the magnet are selected to have the same temperature coefficient,
The temperature coefficient differs between the two sets of magnets and the two sets of auxiliary magnets,
The magnetic flux density ratio between the two sets of magnets and the two sets of auxiliary magnets at the installation point of the magnetic detection element is the reciprocal of the temperature coefficient ratio between them,
A magnetic material detector, wherein magnetic lines of force between the set of two magnets and the set of auxiliary magnets in the installation point of the magnetic detection element are provided in a repulsive direction. I will provide a.
In this invention of Claim 8, in the magnetic body detector of any one of Claims 5-7, the said magnetic path member is an at least opposing surface of the said magnetic detection element and the said 2 sets of magnets. Provided is a magnetic substance detector which is interposed between them.
According to a ninth aspect of the present invention, in the magnetic detector according to the sixth or seventh aspect, each of the two magnets and the two auxiliary magnets has a magnetic pole axis direction to be detected. Provided is a magnetic substance detector, which is arranged so as to be substantially parallel to an operation direction of a magnetic substance to be detected when the magnetic substance is closest.
According to a tenth aspect of the present invention, in the magnetic detector according to the sixth or seventh aspect, each of the two magnets and the two auxiliary magnets has a magnetic pole axis direction to be detected. Provided is a magnetic substance detector which is arranged so as to be in a direction substantially perpendicular to the operation direction of a magnetic substance to be detected when the magnetic substance is closest.
According to the eleventh aspect of the present invention, in the magnetic detector according to any one of the first to tenth aspects, the magnetic path member is made of a soft magnetic material having a thickness of 2 mm or less. A magnetic material detector is provided.
[0011]
(Function)
According to the present invention, since the magnetic path member that attenuates the magnetic force supplied from the magnet is interposed between the magnet and the magnetic detection element, the magnetic detection element is arranged with respect to the detection surface (surface). It can be placed at a position away from the magnet. Thereby, when it attaches to attachment object parts, such as a cylinder, the influence of the external force by the tightening torque etc. at the time of attachment can be avoided, and there is no fear of an intensity | strength aspect.
[0012]
In addition, by arranging a set of two magnets magnetically at approximately the same distance from the magnetic detection element, the two magnets are connected to each other on the line connecting the approximate centers of the two magnets. Since the operation width (ON width) of the magnetic substance to be detected that moves in the direction parallel to the ellipse is almost constant regardless of the movement direction, there is no problem in the reciprocal operation. Therefore, when it is used as an iron plate proximity type cylinder switch, it is possible to detect not only the stroke end but also the midpoint of the stroke in which the piston reciprocates.
[0013]
Furthermore, in addition to a set of two magnets, a set of two auxiliary magnets are used so that the temperature coefficients of both are different and the magnetic forces of both are in the direction of repulsion, the temperature characteristics can be improved. In particular, if the magnetic flux density ratio between a set of two magnets and a set of two auxiliary magnets at the installation point of the magnetic sensing element is selected as the reciprocal of the temperature coefficient ratio, the temperature coefficient of the magnet used will be offset, As long as there is no such factor (for example, there is a temperature dependency that cannot be ignored by the magnetic detection element), an ideal magnetic detector having no theoretical temperature dependency can be provided.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the magnetic detector of the present invention will be described in more detail based on the embodiments shown in the drawings. FIG. 1 is a schematic view showing a structural example of an iron plate proximity type cylinder switch which is a magnetic substance detector according to a first embodiment of the present invention. (A) is a top view, (b) is a front perspective view. However, parts that do not directly affect the magnetic operation are omitted except for some parts.
[0015]
In FIG. 1, the magnetic detection element 1001 (shown here in the form of a reed switch, but may be another Hall element, magnetoresistive element, magnetoimpedance element, etc.) is located below the magnetic path member 1004, Above the magnetic path member 1004, a set of two magnets (hereinafter referred to as “main magnets”) 1002 and 1003 are arranged in parallel with the X axis at a magnetically approximately equal distance from the magnetic detection element 1001. . In FIG. 1, the main magnets 1002 and 1003 are on the X axis of the Y coordinate 0, but the Y coordinate may not be 0. In this embodiment, as shown in FIG. 1, the magnetic pole axis directions of the main magnets 1002 and 1003 are substantially orthogonal to the operation direction of the detected magnetic body when the detected magnetic body is closest. Is set to This also applies to auxiliary magnets 1005 and 1006 described later. The magnetic pole axis direction of each magnet can be set to a direction substantially parallel to the operation direction of the detected magnetic body when the detected magnetic body is closest, depending on the use of the magnetic body detector (see FIG. 5).
Here, the main magnets 1002 and 1003 are for adjusting the magnetic detection element 1001 magnetically outside the operating limit in a normal state and applying a magnetic field exceeding the operating point when the detected magnetic body to be detected approaches. It is.
[0016]
On the other hand, a set of two auxiliary magnets 1005 and 1006 are arranged below the magnetic detection element 1001 at a substantially equal distance from the magnetic detection element 1001. Further, the auxiliary magnets 1005 and 1006 are in a positional relationship in which the imaginary line connecting the centers of the two magnets is parallel to the imaginary line connecting the centers of the two main magnets 1002 and 1003, that is, FIG. It arrange | positions in parallel with the X-axis shown to (b). However, the Y coordinate may not be 0 as described above. The auxiliary magnets 1005 and 1006 may be disposed in close contact with the lower surface of the magnetic path member 1004.
[0017]
Each of the above components is housed in a case 1007 (mainly made of iron) and sealed with a mold resin 1008. In addition, the AA surface, which is a detection surface, is attached to the cylinder so as to face the cylinder tube through an appropriate gasket or the like.
[0018]
When the piston of the cylinder, which is the magnetic body to be detected, is separated, most of the lines of magnetic force of the main magnets 1002 and 1003 pass through the magnetic path member 1004 and the case 1007 as shown in FIG. It leaks from 1004 and acts on the magnetic detection element 1001.
[0019]
Similarly, most of the magnetic lines of force of the auxiliary magnets 1005 and 1006 pass through the case 1007, and a part of them acts in a direction repelling the magnetic lines of force generated by the main magnets 1002 and 1003 on the magnetic detection element 1001.
[0020]
Here, the necessity of the magnetic path member 1004 will be described. Generally, when the object to be detected is not a magnet but a magnetic body, it is advantageous to use a strong magnet as an element for improving detection performance. Become. For this reason, the conventional iron plate proximity type cylinder switch 200 is used in combination with a large magnet as shown in FIGS. 6 (a) and 6 (b).
[0021]
The disadvantage of the conventional cylinder switch 200 is that the positional relationship between the reed switch 2001, which is a magnetic detection element, and the magnet 2002 cannot be made magnetically symmetrical as described above. The detection operation for the piston of the cylinder moving upward (X → −X or −X → X) cannot be performed symmetrically. For this reason, it is unsuitable for detecting the intermediate point of the reciprocating piston, and its use is limited for detecting the stroke end. On the other hand, according to the present embodiment, the two main magnets 1002 and 1003 are magnetically arranged at substantially equal distances from the respective centers to the magnetic detection element 1001, so that the detection target piston Regardless of the movement direction (X → −X or −X → X), the operation width (ON) width can be made constant, and an intermediate point can be detected.
[0022]
On the other hand, in the arrangement structure in which the main magnets 1002 and 1003, the magnetic path member 1004, and the magnetic detection element 1001 are arranged in this order from the side close to the detection surface (AA plane) as in the present embodiment, the magnetic path member 1004. Without this, in most cases, the magnetic detection element 1001 cannot be turned on. Even if the main magnets 1002 and 1003 are considerably weakened or the auxiliary magnets are strengthened and can be adjusted to the state immediately before being turned on, the original purpose cylinder for the small change in magnetic force when the piston comes close. Therefore, the magnetic detection element 1001 does not react.
[0023]
However, if the magnetic path member 1004 is provided, the main magnets 1002 and 1003 can be selected as magnets having the strength necessary to obtain a change in magnetic force depending on the presence or absence of the piston of the cylinder that is the detected magnetic body. As is convenient for the operating range, the magnetic force from the main magnets 1002 and 1003 can be attenuated and supplied to the magnetic detection element 1001. Then, by interposing the magnetic path member 1004 between the main magnets 1002 and 1003 and the magnetic detection element 1001, the main magnets 1002 and 1003 are disposed on the detection surface (AA plane) side as described above. This makes it possible to eliminate the anxiety of the strength of the magnetic detection element 1001 when it is attached to the cylinder.
[0024]
In FIG. 1, the magnetic path member 1004 is simply shown as a flat plate, but the magnetic path member 1004 is physically shielded between the magnetic detection element 1001 and the main magnets 1002 and 1003 at least between the opposing surfaces. Anything to do. Therefore, the present invention is not limited to the shape shown in FIG. 1, and is effective, for example, as a structure that is bent toward the magnetic detection element 1001 and covers at least one other surface of the magnetic detection element 1001 or the entire surrounding area. . It can also be bent toward the main magnets 1002, 1003. However, in this case, the detection surface (A-A surface) is bent so long as it is not covered.
[0025]
As a material of the magnetic path member, a soft magnetic material such as permalloy, electromagnetic soft iron, electromagnetic stainless steel, soft ferrite, SPC, or the like is suitable so as to meet the above-described action. The thickness is preferably 2 mm or less, more specifically, 2 mm or less in the case of soft ferrite, and 0.5 mm or less in the case of the other soft magnetic materials.
[0026]
It is assumed that the piston of the cylinder, which is the magnetic body to be detected, approaches the iron plate proximity cylinder switch 100, which is the magnetic body detector of the present embodiment, and is 10 mm above the AA plane in FIG. To do. In this case, the total magnetic flux entering and exiting from the main magnets 1002 and 1003 is unchanged, and there is no change before and after the detected magnetic body approaches, but the path is considered to change. That is, the main magnets 1002 and 1003 form a magnetic field as shown in FIG. 2 before the piston of the cylinder, which is the magnetic body to be detected, approaches. On the other hand, when the piston 4001 of the cylinder, which is the magnetic body to be detected, is in the immediate vicinity, as shown in FIG. 3, a part of the magnetic flux that has leaked from the main magnets 1002 and 1003 to the case side before that time. It passes through the cylinder piston and its vicinity.
[0027]
Therefore, as the return path of the magnetic flux, since the magnetic path member 1004 is partially in a magnetic saturation state, the amount of magnetic flux leaking out to the periphery and passing through the magnetic detection element 1001 increases. As a result, the magnetic detection element 1001 Since the operating point is exceeded, the engine is turned from OFF to ON, and the piston 4001 of the cylinder is detected.
[0028]
Now, the operation of the auxiliary magnets 1005 and 1006 will be described. The auxiliary magnets 1005 and 1006 according to the present invention are not simply magnets for adjusting the direction of canceling the magnetic flux by the main magnets 1002 and 1003 as is well known.
[0029]
The purpose of providing the auxiliary magnets 1005 and 1006 in the present invention is to improve the temperature characteristics and is not necessary when the operating temperature range is narrow, but for the case where the operating temperature range is wide and the influence of temperature on the detection characteristics cannot be ignored. Therefore, it provides a very effective means.
[0030]
That is, as shown in FIG. 4 in which the main magnets 1002 and 1003 and the auxiliary magnets 1005 and 1006 in FIG. 1A are extracted, the magnetic flux by the main magnets 1002 and 1003 at the point P assuming the installation point of the magnetic detection element 1001. Assuming that the density is B ₁ and the magnetic flux density by the auxiliary magnets 1005 and 1006 is B ₂ , B _{1 (T)} and B _{2 (T) at} the temperature T (° C.) can be expressed by the following equations (based on the B ₁ direction) And).
[0031]
B _{1 (T)} = B ₁ (1 + αΔT) (1)
−B _{2 (T)} = − B ₂ (1 + βΔT) (2)
The negative sign of _{B 2} is _{B 2} means the opposite direction to the _{B 1.}
In the above equations (1) and (2), α and β are the temperature coefficients of the main magnet and the auxiliary magnet.
[0032]
Here, if terms that affect the temperature change are extracted from Equations (1) and (2),
B _{1 (ΔT)} = B ₁ αΔT (3)
−B _{2 (ΔT)} = − B ₂ βΔT (4)
It becomes.
[0033]
Therefore, in order for the resultant magnetic flux density at point P not to affect the temperature change,
B _{1 (ΔT)} −B _{2 (ΔT)} = 0 (5)
B ₁ αΔT-B ₂ βΔT = 0 (6)
Therefore, B ₁ / B ₂ = β / α (7)
The following relational expression holds.
That is, two sets of main magnets 1002 and 1003 are composed of magnets having the same temperature coefficient, and two sets of auxiliary magnets 1005 and 1006 are also composed of magnets having the same temperature coefficient. The combination of the magnets 1002 and 1003 and the auxiliary magnets 1005 and 1006 have different temperature coefficients, and the magnetic flux density ratio at the installation point of the magnetic detection element 1001 is the reciprocal of the temperature coefficient ratio. The structure is such that the magnetic lines of force of the two sets of magnets at the installation point of the magnetic detection element 1001 are in a direction in which they repel each other.
[0034]
For example, when a cobalt rare earth magnet is used for the main magnets 1002 and 1003 and a ferrite magnet is used for the auxiliary magnets 1005 and 1006, the temperature coefficient of the cobalt rare earth magnet is −0.03% / ° C. and the temperature of the ferrite magnet Since the coefficient is −0.18% / ° C., the magnetic flux density ratio by the main and auxiliary magnets at the point P is substituted into the equation (7).
B ₁ / B ₂ = −0.18% / ° C./−0.03%/° C. = 6/1
The relationship. Thereby, the iron plate proximity type cylinder switch which is not influenced by temperature can be provided. Therefore, it is preferable to provide auxiliary magnets 1005 and 1006 as in this embodiment.
[0035]
FIG. 5 shows a second embodiment of the present invention. FIG. 5 is a schematic structural diagram of a normally close type iron plate proximity magnetic proximity switch 600, and members that do not affect the magnetic operation are omitted. In FIG. 5, a magnetic detection element 6001 (shown here in the form of a reed switch, but may be another Hall element, magnetoresistive element, or magnetoimpedance element) is placed inside a magnetic path member 6003 bent into an L shape. The magnet 6002 having a magnetic pole axis direction parallel to the operation direction of the iron plate 6004 to be detected is fixed to the magnetic path member 6003 at the substantially central portion outside.
[0036]
The magnetic path member 6003 is selected so that the magnetic detection element 6001 reverses its operation (ON → OFF) when the detected iron plate 6004 approaches within a predetermined interval. The difficulty when the iron plate is a magnetic body to be detected is that the magnetization state of the iron plate changes, and if you want to avoid the influence of the magnetization state, a large or small magnet with a strong coercive force is required. It is.
[0037]
On the other hand, in response to the conflicting demand to make the switch as small a shape as possible, conventionally, a magnetic circuit has been created by trial and error (for example, an empirical arrangement is employed in combination with a repulsive opposing magnet). ) However, in the conventional method, there are not a few defects due to component variations and the like. In the iron plate proximity type magnetic proximity switch 600 of this embodiment, the conventional problem is solved by arranging the magnetic path member 6003 bent into an L shape between the magnet 6002 serving as a magnetic source and the magnetic detection element 6001 as an example. Is.
[0038]
That is, since the magnetic path member 6003 is provided, as described in the above embodiment, a small and strong magnet that gives a sufficient magnetic force to the iron plate 6004 can be adopted as the magnet 6002, and the magnetic force at the position of the magnetic detection element can be adopted. There is room for change, and it can absorb fluctuations in the magnetic operating point due to component variations. In this embodiment, the L-shaped magnetic path member 6003 is used. However, as long as it is interposed between at least the opposing surfaces of the magnet 6002 and the magnetic detection element 6001, other shapes are used as described in the above embodiment. Also good.
[0039]
However, when a strong magnet is used as the magnet 6002, the area is dominant when the magnetic path member 6003 is made of the same material and has the same thickness in order to limit the magnetic force more than necessary to enter the magnetic detection element 6001. In order to make the iron plate proximity type magnetic proximity switch 600 as compact as possible, it is preferable to bend the magnetic path member 6003 as shown in FIG.
[0040]
【The invention's effect】
The magnetic substance detector of the present invention is accommodated in the case in the order of the magnet and the magnetic detection element from the side close to the detection surface, and a magnetic path member that attenuates the magnetic force supplied from the magnet is interposed therebetween. Yes. Accordingly, a thicker protective material (mold resin) for protecting the magnetic detection element can be secured, and the anxiety regarding the strength of the magnetic detection element when attached to the attachment target site can be eliminated.
In addition, by using two magnets as a set and arranging them magnetically at substantially equal distances from the magnetic detection elements, it is a magnetic material to be detected when used as an iron plate proximity type cylinder switch. Regardless of the moving direction of the piston, the operation width (ON width) is substantially constant, so that the detected magnetic body can be detected not only at the stroke end of the cylinder but also at the midpoint of the stroke. In addition to the magnet (main magnet) for operating the magnetic sensing element, an auxiliary magnet is provided, and a combination that takes into account the temperature coefficient of the magnet used for these, theoretically temperature dependence if necessary. It is possible to provide a magnetic material detector that does not have any.
Furthermore, according to the magnetic substance detector of the present invention, when used as a normally closed type switch, the magnetic path member is interposed between the magnet and the magnetic detection element, thereby There is no problem with respect to the adverse effect on the detection characteristics due to the change in the magnetization state of a certain iron plate or the like.
[Brief description of the drawings]
FIG. 1 is a schematic view showing the structure of an iron plate proximity cylinder switch according to a first embodiment constituting a magnetic detector of the present invention, wherein (a) is a plan view and (b) is a front perspective view. Each is shown.
FIG. 2 is a distribution diagram of magnetic lines of force when there is no detected magnetic body of the iron plate proximity type cylinder switch according to the first embodiment.
FIG. 3 is a distribution diagram of lines of magnetic force when the detected magnetic body of the iron plate proximity cylinder switch according to the first embodiment is in the immediate vicinity.
FIG. 4 is a diagram for explaining a temperature operation in which a magnet arrangement of the iron plate proximity type cylinder switch according to the first embodiment is extracted.
FIGS. 5A and 5B are schematic structural views of a normally closed type iron plate proximity magnetic proximity switch according to a second embodiment constituting the magnetic detector of the present invention, wherein FIG. 5A is a plan view and FIG. 5B is a plan view; Front views are shown respectively.
6A and 6B are schematic views showing the structure of a conventional iron plate proximity cylinder switch, where FIG. 6A is a plan view and FIG. 6B is a front perspective view.
[Explanation of symbols]
100 Iron Plate Proximity Type Cylinder Switch 1001 Magnetic Detection Element 1002 Main Magnet 1003 Main Magnet 1004 Magnetic Path Member 1005 Auxiliary Magnet 1006 Auxiliary Magnet 1007 Case 1008 Mold Resin 4001 Detected Magnetic Body 600 Iron Plate Proximity Type Magnetic Proximity Switch 6001 Magnetic Detection Element 6002 Magnet 6003 Magnetic passage member 6004 Detected iron plate

Claims (11)

A magnetic sensing element;
A magnet for magnetically adjusting the magnetic detection element outside the operating limit in a normal state and applying a magnetic field exceeding the operating point when approaching a detected magnetic body to be detected;
The magnetism detection element and the magnet are accommodated in the case in the order of the magnet and the magnetism detection element from the side close to the detection surface facing the magnetic substance to be detected, and between the magnet and the magnetism detection element, A magnetic material detector comprising a magnetic path member for attenuating magnetic force supplied from a magnet. 2. The magnetic substance detector according to claim 1, wherein the magnetic path member is interposed between at least opposing surfaces of the magnetic detection element and the magnet. 2. The magnetic body detector according to claim 1, wherein the magnet is arranged so that a magnetic pole axis direction thereof is substantially parallel to an operation direction of the detected magnetic body when the detected magnetic body is closest. Characteristic magnetic detector. 2. The magnetic body detector according to claim 1, wherein the magnet is arranged such that a magnetic pole axis direction thereof is substantially perpendicular to an operation direction of the detected magnetic body when the detected magnetic body is closest. A magnetic substance detector. The magnetic body detector according to claim 1, wherein the magnet is composed of a set of two magnets, and the magnetic detection element is magnetically equidistant from the center of the two magnets via the magnetic path member. It is arrange | positioned in the magnetic substance detector characterized by the above-mentioned. 6. The magnetic substance detector according to claim 5, further comprising: a set of two auxiliary magnets that are substantially equidistant from each other and spaced between the centers of the two auxiliary magnets. A magnetic substance detector characterized in that an imaginary line to be connected is housed in a case in a positional relationship parallel to an imaginary line connecting the centers of the two magnets. 7. The magnetic detector according to claim 6, wherein magnets having the same temperature coefficient are selected as the magnets constituting the two sets of magnets, and the magnets constituting the two sets of auxiliary magnets are heated to each other. While equal coefficients are selected,
The temperature coefficient differs between the two sets of magnets and the two sets of auxiliary magnets,
The magnetic flux density ratio between the two sets of magnets and the two sets of auxiliary magnets at the installation point of the magnetic detection element is the reciprocal of the temperature coefficient ratio between them,
A magnetic material detector, wherein magnetic lines of force between the set of two magnets and the set of auxiliary magnets in the installation point of the magnetic detection element are provided in a repulsive direction. . 8. The magnetic detector according to claim 5, wherein the magnetic path member is interposed between at least opposing surfaces of the magnetic detection element and the set of two magnets. 9. Magnetic substance detector. 8. The magnetic material detector according to claim 6, wherein the two sets of magnets and the two sets of auxiliary magnets are detected when their magnetic pole axis directions are closest to the detected magnetic material. A magnetic body detector, characterized in that the magnetic body detector is arranged so as to be substantially parallel to an operation direction of the magnetic body. 8. The magnetic material detector according to claim 6, wherein the two sets of magnets and the two sets of auxiliary magnets are detected when their magnetic pole axis directions are closest to the detected magnetic material. A magnetic material detector, wherein the magnetic material detector is disposed so as to be substantially perpendicular to an operation direction of the magnetic material. 11. The magnetic substance detector according to claim 1, wherein the magnetic path member is made of a soft magnetic material having a thickness of 2 mm or less.

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