JPH11202036A - Magnetic sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a compact magnetic sensor that can also be used near equipment for generating a storing magnetic field. SOLUTION: A magnetic sensor 1 accommodates two permanent magnets 3A and 3B and a Hall IC 2 in a container 6. In the magnets 3A and 3B, the same-polarity sides oppose each other and a magnetic flux is concentrated at the Hall IC 2 by cores 4A, 4B. A balancing point is provided at the middle part of the both magnets so that it cancels a magnetic flux in the direction of a straight line for connecting the both magnets. An auxiliary core 5 adjusts the magnetic distribution of the magnet 3A and adjusts the amount of offset of the balancing point of the magnetic flux for the detection surface of the Hall IC 2. As result, by offsetting the balancing point of the magnetic flux due to the magnetic in the sensor from the detection surface of the Hall element by given amount in accordance with the density and direction of the magnetic flux being generated by peripheral equipment in advance, a magnetic sensor can be used also near an electromagnetic clutch or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic sensor particularly suitable for use as a rotation sensor, and more particularly to a magnetic sensor which is small and can be used near an apparatus which generates a strong magnetic field.

[0002]

2. Description of the Related Art Conventional magnetic sensors of this type include:
For example, an electromagnetic power generation type magnetic sensor using a coil and a permanent magnet is widely known. In this magnetic sensor, when a magnetic body approaches or separates from the detection end face, the magnetic flux passing through the sensor changes, and an alternating voltage is generated at both ends of the coil.

In order to obtain a sufficient output in such an electromagnetic power generation type magnetic sensor, it is necessary to increase the number of turns of the coil or to make the magnet strong. However, increasing the number of turns of the coil causes a problem that the sensor becomes large. In order to make the magnet strong, the size of the iron core and the like are increased, and the material cost is increased. Further, the electromagnetic power generation type has a problem that the output fluctuates depending on the moving speed of the magnetic substance to be detected, and there is a possibility that a sufficient output cannot be obtained particularly in a low speed region.

Therefore, in addition to the electromagnetic power generation type, a semiconductor type using a Hall element as a magnetoelectric conversion element or a Hall IC combining a Hall element and an amplifier circuit is known. The Hall element performs an analog output according to the magnetic flux density. The Hall IC internally processes the output of the Hall element and outputs an ON-OFF signal. Both are essentially the same, but here, Hall I
C will be described as an example with reference to FIGS. FIG.
3 is a characteristic diagram of a Hall IC that is a magnetoelectric conversion element. The horizontal axis of this characteristic diagram represents the density and direction of a magnetic flux component (hereinafter, referred to as an orthogonal magnetic flux component to the Hall IC) perpendicular to the detection surface of the magnetic flux passing through the detection surface of the Hall element in the Hall IC. The direction of the magnetic flux component is reversed in the normal and reverse directions with respect to the point where the density of the orthogonal magnetic flux component becomes zero with respect to. The vertical axis indicates the output voltage of the Hall IC. Hall I
FIG. 2C shows an alternating magnetic field type in which operating points are set substantially symmetrically with respect to a magnetic flux density of 0 point as shown in FIG.
As shown in (B), there is a one-side magnetic field type in which the operating point is slightly shifted to one of the magnetic poles, but the operation method is the same in both cases.

The Hall IC changes the output voltage Vout to a high output state H and a low output state L depending on the intensity of the magnetic flux received from the outside.
The output voltage Vout changes from H to L when the orthogonal magnetic flux component density for the Hall IC changes from left to right in FIG. 2 and exceeds the operating magnetic flux density Bop. When the magnetic flux density becomes equal to or lower than the return magnetic flux density Brp in the low output state L, the output voltage changes from L to H.

In a magnetic sensor using this Hall IC as a magnetoelectric conversion element, the positional relationship between the Hall IC and a magnet is fixed, and a magnetic substance such as iron, which is a detection target, is moved closer to or away from the magnetic sensor, so that the magnetic flux passing through the Hall IC is reduced. There is a type that changes the distribution, and a type that changes the magnetic flux distribution with respect to the Hall IC by moving by attaching the magnet itself that generates the magnetic flux as a detection target to a rotating part of the device to be protected. The operation when this magnetic sensor is used for a compressor for a car air conditioner will be described. Usually, a compressor for a car air conditioner obtains a driving force from an engine via a belt or the like, and the driving force is transmitted and released by an electromagnetic clutch. The magnetic sensor detects the rotation of the compressor, and when the compressor becomes locked due to some cause and cannot rotate, disconnects the electromagnetic clutch so that the engine will not be affected. . FIG. 3 shows the distance D between the end face of the magnetic sensor and the magnetic material to be detected on the horizontal axis.
And the vertical axis shows the magnetic flux component density B orthogonal to the Hall IC in the magnetic sensor, showing the relationship between the two. FIG. 3 shows an example of characteristics of a conventional magnetic sensor.
In (B), the Hall IC depends on the position of the detection target.
The magnetic flux component density orthogonal to the above changes with a characteristic as shown by a curve L3, for example.

In this example, when the sensor is used alone, the magnetic flux density component orthogonal to the Hall IC is set to be equal to or lower than the return magnetic flux density Brp. Or it is shifted to the south pole side. In this example, the position is shifted to the S pole side by approaching. Here, in the case where there is no influence from the leakage magnetic flux from the outside, in order to obtain a signal due to the operation of the detection target by using the one-sided magnetic field type Hall IC, the magnetic flux density component orthogonal to the Hall IC becomes the operating magnetic flux density Bop and It is sufficient that the moving range of the detection target includes the positions Dc and Dd so as to change beyond the range of the return magnetic flux density Brp, and the moving distance of the detection target needs to be at least d2 or more.

However, in FIG. 3B, the orthogonal magnetic flux component of the leakage magnetic flux density from the outside by a device mounted around the magnetic sensor with respect to the Hall IC greatly exceeds the operating magnetic flux density Bop as shown by a curve L2. When the distance D between the magnetic sensor and the detection target such as a magnetic material is within the range shown in the figure, the synthetic magnetic flux does not drop below the operating magnetic flux density Bop, as shown by the curve L3 + L2. The output from the sensor is always in a high output state. In other words, if the magnetic sensor is at the same position as the conventional one and the magnetic body is close to or separated by a distance of about d2, the orthogonal magnetic flux component cannot be changed across the magnetic flux density for the operation and return of the Hall IC. However, the output of the magnetic sensor cannot be changed. In FIG. 3, the leakage magnetic flux indicates a value in a state where the electromagnetic clutch is completely connected, and indicates a steady state magnetic flux density when the reluctance at the moment of suction or release of the clutch movable plate is not included. ing.

Further, in a magnetic sensor in which a Hall IC and one permanent magnet are mounted in one housing, it is more difficult to make the magnetic sensor compact and operate sufficiently. This will be described with reference to FIG. The leakage magnetic flux orthogonal to the Hall IC is indicated by a curve L2 as in the above-described example. For example, when the direction of the leakage magnetic flux and the direction of the magnetic flux of the magnet are the same, the combined magnetic flux of the two is naturally stronger than this curve L2, and is not smaller than the operating magnetic flux density Bop and the return magnetic flux density Brp of the Hall IC, and the output is smaller. Needless to say, the switching is not performed, and the description is omitted.

Next, even when the magnetic flux is directed in the direction to cancel the leakage magnetic flux, the magnetic flux density on the surface of the magnet is usually much higher than the leakage magnetic flux.
The Hall IC and the magnet cannot be adjacent to each other because the magnetic flux passing through the hole becomes too strong in the opposite direction. Therefore, it is necessary to reduce the magnetic flux density passing through the Hall IC by dispersing the magnetic flux by increasing the distance between the Hall IC and the magnet or devising the shape of the iron core or the like. Here, when the distance between the Hall IC and the magnet is increased to reduce the magnetic flux density reaching the Hall IC, in order to obtain a sufficient distance, the magnetic sensor itself containing the magnet and the Hall IC must be downsized. Becomes difficult.

On the other hand, when the shape of the iron core is devised so as to reduce the magnetic flux density by mounting a large iron core with a smaller magnet, the distance between the magnet and the Hall IC is increased. The synthesized magnetic flux can be reduced to near the operation and return magnetic flux densities without significantly increasing the size of the sensor. This state is shown in FIG.
It is shown in (C). However, along with the movement of the magnetic material, the leakage magnetic flux density perpendicular to the Hall IC shown by the curve L2 changes, and at the same time, the magnetic flux from the magnet shown by the curve L4 applied in the opposite direction to the leakage magnetic flux also changes. Therefore, the magnetic flux from the magnet cancels out the increase in the magnetic flux density when the magnetic body approaches the magnetic sensor.
The change rate of the synthetic magnetic flux indicated by L2 is reduced.

That is, if the magnetic flux density passing from the magnet to the Hall IC is constant, the leakage magnetic flux L2 is offset in the same curve shape downward in the figure, and the rate of change can be used. Can be obtained so as to pass through the operation and return magnetic flux densities. However, in practice, the magnet is also affected by the distance from the magnetic body, and when the magnetic body approaches as shown by the curve L4, the magnetic flux density becomes stronger in the direction opposite to the leakage magnetic flux. Combined magnetic flux L4 combined with magnetic flux L4
At + L2, the rate of change of each magnetic flux is canceled out and hardly changes. Therefore, the combined magnetic flux L4 + L2
Becomes difficult to change beyond the range of the operating magnetic flux density Bop and the return magnetic flux density Brp.

[0013] Accordingly, the applicant has filed Japanese Patent Application No. 9-145875.
No. 2 has a magnet for generating a magnetic field and a magnetoelectric conversion element,
In a magnetic sensor that detects a change in a magnetic field due to proximity and separation of a magnetic body, the magnet is configured with at least two magnets, and the magnetoelectric conversion element is arranged so as to be sandwiched in a detection direction, and the same poles face each other. A magnetic sensor characterized by being arranged as described above was proposed. In this magnetic sensor, a magnetically sensitive element is disposed at a position where a magnetic flux component in a direction connecting both magnets is canceled between magnets having the same poles facing each other. With this configuration, the magnetic flux component in the short distance direction connecting between the magnets becomes maximum in the positive direction on one of the magnet surfaces, becomes 0 at the intermediate point,
It becomes maximum in the negative direction at the other magnet surface. On the other hand, when the number of magnets is one, the point at which the magnetic flux becomes maximum on the magnet surface is the same, but the magnetic flux component becomes zero at a position at infinity from the surface and the rate of change of the magnetic flux density is low. By using two magnets in this way, the rate of change of the magnetic flux component density in the direction connecting the two magnets becomes larger than that of the conventional one, and the magnetism due to the magnetic body approaching and separating from the detection end face of the magnetic sensor. The amount of change in magnetic flux passing through the sensitive element can be increased.

[0014]

As described above, one of the use environments of the magnetic sensor is to detect the rotation of a compressor for a car air conditioner. This is to prevent the engine that is driving the compressor from rotating even if the compressor becomes locked due to some cause and does not affect the engine.If the rotation detection signal from the magnetic sensor is interrupted, the engine will stop. By disconnecting the power supply to the electromagnetic clutch that connects the compressor and the compressor, the connection is released, and damage to the engine and the belt for driving the compressor can be prevented.

However, when a magnetic sensor for detecting a relatively small change in magnetic flux is attached to a compressor for a car air conditioner, a magnetic flux leaking from the electromagnetic clutch which generates a strong magnetic field reaches the magnetic sensor. The detection part of the sensor has a magnetic flux density exceeding the operating range of the sensor, and as it is
There has been a problem that a change in magnetic flux due to separation cannot be detected.

[0016]

Accordingly, a magnetic sensor according to the present invention is disposed in a magnetic circuit through which a magnetic flux generated by a device to be protected or its peripheral device passes, and includes a magnet for generating a magnetic field and a magnetoelectric conversion element. The magnetic flux of the magnetic circuit has an orthogonal magnetic flux component on the detection surface of the magneto-electric conversion element, and in a magnetic sensor for detecting a change in a magnetic field due to the proximity and separation of a magnetic body, the magnet is sufficient for the magneto-electric conversion element. The magnet is composed of at least two magnets, and the magnet is arranged so as to sandwich the magneto-electric conversion element in the detection direction, and the same poles face each other. Are arranged in a predetermined offset amount from the position of the magneto-electric conversion element in advance, where the orthogonal magnetic flux component density on the sensing surface of the magneto-electric conversion element between the magnets is substantially zero. When the device to be protected is operating, the magnetic flux generated by the device to be protected or its peripheral devices is stationary, and by synthesizing this magnetic flux, the position where the magnetic flux density between the magnets becomes almost zero is determined. The magnet is changed to a position where the magnetic flux of the magnet is balanced with the magneto-electric conversion element so as to be moved to or near the detection surface of the magneto-electric conversion element.

In this way, by taking into account the density and direction of the orthogonal magnetic flux component with respect to the Hall IC at the mounting position in advance, the magnetic flux balance position is offset by a predetermined amount from the position of the magneto-electric conversion element, so that the magnetic sensor can be operated at a predetermined magnetic field. When the magnetic sensor is mounted near a peripheral device which generates magnetic flux, the magnetic flux balance position of the magnetic sensor is offset by a predetermined amount due to the magnetic flux generated by the device, and the magnetic flux can be balanced on or near the magnetoelectric conversion element. Therefore, even if there is an electric device or the like that generates a strong magnetic field in the vicinity, it is possible to use an element that operates with high accuracy in a relatively low magnetic flux density range, such as a Hall IC, for example, as a magnetoelectric element, The influence of the magnetic flux exerted from the surroundings can be substantially neglected, and a signal can be output reliably due to the proximity / separation of the magnetic material.

Another feature is that the orthogonal magnetic flux component of the magnetic flux generated by the device to be protected or its peripheral device on the detection surface of the magneto-electric conversion element of the magnetic circuit determines the magnetic flux density passing through the magneto-electric conversion element. That changes in conjunction with the operation of.

Another feature is that it comprises a main body having a magneto-electric conversion element and a separate magnet for generating a magnetic field. The magnet is attached to an operating portion of a device to be protected, and a magnetic flux caused by the proximity and separation of the magnet. In a magnetic sensor for detecting a change in density, a sensor main body is disposed in a magnetic circuit through which a magnetic flux generated by a device to be protected or its peripheral device passes, and the magnetic circuit passes through a magneto-electric conversion element with the operation of the device to be protected. The magnet for generating a magnetic field is attached to the magneto-electric conversion element so as to generate a magnetic flux in a direction that substantially cancels a magnetic flux component orthogonal to a detection surface of the magneto-electric conversion element by the magnetic circuit. It is in.

As described above, in a device in which the magnetic flux density passing through the magnetic circuit changes due to a change in the position of the magnetic material in the magnetic circuit accompanying the operation of the device to be protected, a magnetic sensor is mounted on the magnetic circuit. When the protection target device operates, the change in magnetic flux density by the magnetic sensor itself and the change in magnetic flux density by the magnetic circuit can be overlapped during operation of the device to be protected, and the change in the orthogonal magnetic flux component density with respect to the magnetoelectric conversion element in the magnetic sensor is further increased. As a result, the operation as a sensor can be made more reliable, and downsizing can be facilitated.

[0021]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a magnetic sensor according to an embodiment of the present invention. A magnetic sensor 1 shown in a cross-sectional view in FIG. 1 has a Hall IC 2 as a magnetoelectric conversion element and two rare-earth magnets 3A and 3B as magnets for generating a magnetic field arranged so as to sandwich the Hall IC 2.
have. The magnets 3A and 3B are magnetized in the left-right direction in the figure, and have the same polarity, for example, S poles with the hole I.
I'm aiming for C2. The distance between the magnet and the Hall IC is defined by the iron cores 4A and 4B. In addition, this iron core 4A, 4
The shape B is a shape for concentrating the magnetic flux of the magnets 3A and 3B on the Hall IC. The reason for using a rare earth magnet in the present embodiment is that it does not demagnetize even at low temperatures,
When the use environment is not so severe, it is sufficiently possible to use a ferrite magnet or the like.

Here, the magnets 3A and 3B are directed to the Hall IC 2 with the same polarity to each other as described above, and have a position between the two magnets to substantially cancel the orthogonal magnetic flux component with respect to the detection surface of the Hall IC. The reason will be described. The graph of FIG. 5 shows the magnetic flux density distribution between the two magnets 3A and 3B when the same poles face each other at a distance d0 as shown in FIG. The horizontal axis of this graph represents the distance D in the vertical direction to the surface of the magnet 3A,
The vertical axis indicates the magnetic flux density B of the vertical component, and shows the relationship between the two. For example, assuming that the magnet 3B has been removed here, the magnetic flux from the magnet 3A is represented by a curve B
As shown in FIG. 1, at the position of D = 0 on the magnet surface, it is B0, and approaches 0 at infinity while decreasing the change rate.

For example, the magnetic flux density on the magnet surface in the magnetic sensor is very high. For example, when the rare earth magnet used in the embodiment is used, the magnetic flux density on the magnet surface is about 20%.
As many as 00 Gauss. On the other hand, the leakage magnetic flux density received by the magnetic sensor from the device to be protected differs depending on the device to be protected and the mounting position, but is usually several tens of gauss.
It is necessary to increase the distance between the hole IC and the detection surface 2A of the Hall IC. Therefore, if one magnet is used, the number of parts is reduced, but the size of the sensor is not reduced. If a weak magnet is used, the distance between the magnet and the Hall IC does not need to be increased, but in this case, a sufficient change in magnetic flux density can be achieved unless the difference between the distance to the detection target and the distance to the detection target is increased. There is a problem that cannot be obtained. Further, since the magnetic flux B1 cannot be 0 or less, an alternating magnetic field type Hall IC cannot be used.

On the other hand, in the case of the present invention, since the magnetic field is canceled by a plurality of magnets, the magnetic flux density in the direction orthogonal to the detection surface of the Hall IC is reduced to 0 regardless of the strength of the magnet alone. Since it can be made to be about Gaussian, it is easy to select a magnet and the magnetic sensor can be downsized. Also, by using a strong magnet, the rate of change of the magnetic flux density between the magnets, particularly the rate of change near the detection region of the magnetic sensor, can be increased, and the sensitivity as a sensor can be increased.

That is, referring to FIG. 5, by arranging the magnet 3B with the same polarity facing the position of d0 from the surface of the magnet 3A, the magnetic flux B1 from the magnet 3A and the magnetic flux B1 from the magnet 3B in the axial direction of the magnetic sensor. The combined magnetic flux with the magnetic flux B2 is as shown by the curve B1 + B2. In other words, the composite magnetic flux density is maximum on the surface of the magnet 3A, temporarily becomes 0 gauss, that is, a balanced position in the middle, and the direction of the magnetic flux is reversed forward and reverse at the balanced position, and is maximized in the reverse direction on the surface of the magnet 3B. . As can be seen from FIG. 5, this synthetic magnetic flux has a large change rate of the magnetic flux density B with respect to the distance D, and changes from the operating magnetic flux density Bop to the return magnetic flux density Brp in a narrower range d than in the case of one magnet. be able to. Thus, by arranging two magnets in the magnetic sensor, the size of the sensor is reduced and the sensitivity is increased. In addition, magnet 3A,
By adjusting the positional relationship of the sensing surface 2A in the Hall IC with respect to the Hall IC 3B, the magnetic flux component density perpendicular to the Hall IC can be reduced to 0 Gauss or less, so that an alternating magnetic field type Hall IC can be used. . Here, for the sake of simplicity, an example has been described in which the combined magnetic flux with respect to the Hall IC is adjusted by changing the positional relationship between the magnet and the Hall IC. For example, in the magnetic sensor 1, the shapes of the iron cores 4A and 4B are changed. By changing the magnetic flux from the magnets 3A and 3B, the Hall I
The resultant magnetic flux for C is adjusted.

The leakage magnetic flux density received by the magnetic sensor from the device to be protected varies depending on the device to be protected and the mounting position. For example, when the magnetic sensor is mounted on the compressor for a car air conditioner of the embodiment, the leakage magnetic flux density from the electromagnetic clutch is 6%.
It is about 0 Gauss. Therefore, the magnetic flux distribution in the magnetic sensor is offset to such an extent that the magnetic flux density component orthogonal to the Hall IC due to the leakage magnetic flux is eliminated.

As shown in FIG. 1, in this embodiment, an auxiliary iron core 5 is provided on the back surface of the magnet 3A. Therefore, the magnetic flux from the magnet 3A toward the Hall IC becomes stronger than the magnetic flux from the magnet 3B, and the magnetic flux is balanced by the magnet 3B.
Offset to the side. This offset amount is set according to the strength and direction of the leakage magnetic flux received by the sensor in the device to be protected to which the magnetic sensor 1 is attached. For example, instead of providing the auxiliary core 5, the core 4
Adjustment can also be made by changing the shape of A, 4B or by changing the strength of each of the magnets 3A, 3B.

These components are integrally housed in a nonmagnetic case 6 and sealed and fixed by a filler 7 such as a synthetic resin. From the Hall IC 2, a plurality of lead terminals 8 for inputting / outputting a control signal and a detection signal are drawn out.
Terminals 9 electrically connected to the respective lead terminals 8 are led out. In this embodiment, an example is described in which the internal components are put into a case and sealed with a filler, but for example, the internal components are securely fixed in the case and sealed to the extent that there is no problem in use. In this case, the filler is not always necessary. On the contrary, it is needless to say that the case may be omitted by molding the whole with resin or the like.

In a state in which no magnetic flux from the outside acts on the magnetic sensor 1, the balanced position of the magnetic flux is largely offset from the detection surface of the Hall IC, which is a magneto-electric conversion element. In a method in which the body is only close to / separated from the body, there is no change in magnetic flux such that the amount of movement of the balance position is sufficient for the operation of the magnetic sensor. The magnetic sensor 1 is attached to the device to be protected, and the magnetic flux distribution in the magnetic sensor 1 is offset in consideration of the density and direction of the magnetic flux generated by the device to be protected or its peripheral devices during the operation of the device to be protected. Thus, when the leakage magnetic flux flows, a predetermined magnetic flux density is provided in the vicinity of the magnetoelectric conversion element, so that the magnetic sensor operates reliably as a magnetic sensor. Further, by arranging the magnetic sensor on a magnetic circuit including a magnetic material that is close to / separated from the magnetic circuit, by using a change in the leakage magnetic flux density accompanying the movement of the magnetic material, the change in magnetic flux to the magnetic sensor can be increased. It realizes a reliable output change of the magnetic sensor.

This point will be described by taking as an example a case where the magnetic sensor is mounted on a compressor for a car air conditioner which is a device to be protected. First, the operation of the magnetic sensor on the compressor will be described. 4 is connected to an automobile engine via a pulley 202 and a belt (not shown). Here, an electromagnetic clutch 204 is attached between the rotating shaft 203 of the compressor 201 and the pulley 202, and the electromagnetic clutch is not normally connected, and the pulley 202 is freely rotatable, and transmitted from the engine. The rotation is not transmitted to the rotary shaft 203 of the compressor.

When the coil 204A of the electromagnetic clutch 204 is energized, the friction plate 20 rotates in conjunction with the pulley.
2A, a clutch plate 205 made of a magnetic material is pressed to connect the clutch, and the rotating shaft 2 connected to the clutch plate 205
The scroll type compressor unit 206 is driven via the control unit 03.
The compressor 201 is provided with a magnetic sensor 1 for detecting the operation state of the compressor unit 206, and detects the movement of the proximity and separation of a detection target made of a magnetic material in conjunction with the rotational movement of the compressor unit. Output a signal. In this embodiment, the output signal voltage is switched between high and low by detecting the reciprocating motion of the Oldham ring 207 made of a magnetic material provided as a scroll rotation preventing mechanism. This magnetic sensor 1 has a detection end face 6A formed of a magnetic material such as an iron-based material or the like.
07, and is attached so that the output changes between the proximity position and the separation position of the detection target. The circuit for driving the electromagnetic clutch 204 is provided with a signal from the magnetic sensor 1 so as not to affect the engine driving the compressor unit 206 even if the compressor unit 206 becomes locked due to some cause and cannot rotate. The rotation detection signal is constantly monitored. Here, when the rotation detection signal does not change in the high output state or the low output state, it is determined that there is an abnormality, and the connection between the engine and the compressor is released by cutting off the energization to the electromagnetic clutch, and the engine, the timing belt, etc. Damage can be prevented.

Next, the operation of the magnetic sensor 1 in this case will be described. Here, in the invention of claim 1, the leakage magnetic flux is, for example, from a peripheral device that generates a magnetic flux placed in the vicinity of the compressor, and constitutes a magnetic circuit that does not pass through the Oldham ring. Value. Since the magnetic flux distribution in the magnetic sensor 1 is set in advance so as to offset the leakage magnetic flux, the change in the magnetic flux in the magnetic sensor 1 changes the positional relationship between the Oldham ring 207 and the magnets 3A and 3B as in the conventional example. It depends only on the change. The magnetic flux density in this case is not shown, but is obtained by, for example, offsetting the curve L1 shown in FIG. For example, with the amount of movement of the Oldham ring in the compressor as in the embodiment, the magnetic flux density has a fluctuation range of about 5 to 10 Gauss at the mounting position of the Hall IC 2. Even in this state, the magnetic sensor can be used, but the operating magnetic flux density Bop of the Hall IC and the return magnetic flux density Brp
Since there is a difference of several Gauss, the selection range of the model of the Hall IC is narrowed as it is, and the accuracy of adjusting the magnetic flux density with respect to the operating point becomes slightly strict.

On the other hand, in the invention of claim 2,
The leakage magnetic flux is generated by, for example, the above-described electromagnetic clutch 204,
The magnetic material is bypassed into the magnetic sensor 1 via the rotating shaft 203 and the Oldham ring 207 which are magnetic materials. First, no leakage magnetic flux is generated while the electromagnetic coil 204A of the compressor 201 is not energized.
The Hall IC, which is a magnetoelectric conversion element, is kept in a high output state or a low output state regardless of the stop position of the Oldham ring 207 because the magnetic flux distribution in the inside is offset in advance. In the case of the embodiment, the magnetic flux component orthogonal to the Hall IC in the state of the magnetic sensor 1 alone is offset to the N pole side as shown by a curve L1 in FIG. This offset amount is determined by the strength of the magnetic field generated by the device to be protected and its peripheral devices. For example, in this embodiment, the leakage magnetic flux density from the electromagnetic coil passing through the inside of the magnetic sensor 1 is about 60 gauss, and the core and the auxiliary core of the magnetic sensor are selected and offset according to this.

When the compressor 201 is driven, the electromagnetic coil 204A is energized to connect the electromagnetic clutch 204. At this time, the electromagnetic coil 204A is
The main magnetic circuit generates a strong magnetic field for connecting the clutch plate 205 and the clutch plate 205 to the friction plate 2.
Generates a suction force for connecting to 02A. Since this leakage magnetic flux is the same as the above-mentioned conventional example, it is shown as a curve L2 in FIG. The leakage magnetic flux in FIG. 3A shows a relationship in a state where the electromagnetic clutch is completely connected, as in FIG. 3B. The magnetic flux distribution offset in advance in the magnetic sensor 1 is almost canceled by the leakage magnetic flux, and the balanced position of the magnetic flux moves to the vicinity of the detection position of the Hall IC in the magnetic sensor. In the embodiment, by slightly increasing the magnetic offset amount of the magnetic sensor 1, the magnetic flux combined with the leakage magnetic flux is slightly reduced as compared with the conventional example as shown by the curve L1 + L2. When the electromagnetic coil 204A is energized in this way and the electromagnetic clutch 204 is connected, the compressor unit 206 rotates and the Oldham ring 207 starts reciprocating. Thus, the Oldham ring 207 repeatedly approaches and separates from the magnetic sensor 1, and the magnetic flux distribution in the magnetic sensor 1 changes accordingly.

In this embodiment, since the magnetic sensor 1 is mounted on the magnetic circuit including the magnetic material to be detected and approached and separated as described above, for example, the magnetic force due to the proximity and separation of the Oldham ring 207 which is a magnetic material is obtained. Since the strength of the leakage magnetic flux passing through the magnetic circuit changes with the change of the air gap between the sensor 1 and the detection end face 6A, the magnetic sensor 1 can obtain a larger change in the magnetic flux density with respect to the rotation of the compressor unit. . For example, in the embodiment, the leakage magnetic flux density changes by 5 to 10 gauss at the position of the Hall IC at the top dead center and the bottom dead center of the Oldham ring. The magnetic flux density passing through the Hall IC can be changed by about 10 to 20 gauss with the rotation of the compressor unit together with the magnetic flux density change due to only the Oldham ring described above, so that there is sufficient margin for the operation return range of the Hall IC. As a result, the selection operation of the Hall IC and the positioning work at the time of assembly are facilitated.

Referring to FIG. 3A, the magnetic flux L1 + L2 after the synthesis has a large change rate of the magnetic flux density B with respect to the distance D between the sensor and the magnetic substance such as the Oldham ring, so that the operating magnetic flux density is large. The moving distance d1 between the position Da of the detection target that becomes Bop and the position Db of the detection target that becomes the return magnetic flux density Brp can be made smaller than d2 according to the above-described conventional example. In other words, the change in the magnetic flux density can be increased while the detection target has the same moving distance. This is because, in addition to the change in the magnetic flux density of the magnetic sensor alone, the magnetic flux synthesized because the change in the bypass amount of the leakage magnetic flux to the magnetic sensor due to the proximity of the Oldham ring to the magnetic sensor is superimposed. Change rate increases. Further, by appropriately setting the offset amount of the magnetic sensor, the operation and return magnetic flux density B
It is possible to arbitrarily select the positions Da and Db of the detection target corresponding to op and Brp and the moving distance d1 to some extent.

Next, another embodiment will be described. FIG.
FIG. 4 is a partially enlarged view showing a state where a magnetic sensor is attached to a compressor 201 for a car air conditioner similar to the above-described embodiment. This magnetic sensor 11 is a sensor body 1
2 and a separate permanent magnet 13 for generating a magnetic field, and a Hall IC 14 as a magnetoelectric conversion element is disposed in the main body 12. The magnet 13 is attached to the tip of the Oldham ring 207 in the compressor 201 as a detection target, and is arranged so as to be close to and apart from the detection end face 11A of the magnetic sensor 11 when the compressor operates. Also in this embodiment, although not shown, the compressor 201 has an electromagnetic clutch as in the above-described example, and the sensor body 12 and the magnet 13 are both arranged in a magnetic circuit due to magnetic flux leaking from the electromagnetic clutch. You. The magnet 13 is arranged so as to substantially cancel the orthogonal magnetic flux component due to the leakage magnetic flux with respect to the magnetic sensor, and changes the magnetic flux passing through the Hall IC 14 from the operating magnetic flux density to the return magnetic flux density by approaching / separating from the sensor main body 12. It is changed in the range including up to.

In the case of this embodiment, since the magnet is arranged to be close to and separated from the sensor body as a detection object, the same movement is made as compared with the case where the magnetic body is close to and separated as in the above-described example. Even the amount can greatly change the magnetic flux density passing through the magnetoelectric conversion element. Also in this case, the variation range of the orthogonal magnetic flux component density with respect to the magnetic sensor can be set to an arbitrary value by selecting the type of the magnet, the distance when approaching the sensor body, and the like according to the strength of the leakage magnetic flux. Therefore, it is possible to use an alternating magnetic field type or a one-side magnetic field type for the Hall IC. The operation of the sensor due to the change in the magnetic flux density is the same as that in the above-described example, and the description is omitted.

The above-described magnetic sensor changes its output by a change in magnetic flux due to the proximity and separation of a magnetic body or a magnet as a portion to be detected. In the above description, the case of detecting a substantially linear movement of a magnetic body such as an Oldham ring is described. However, it is needless to say that the magnetic body can be used to detect the proximity or separation by attaching the magnetic body to a rotating shaft or the like. No.

[0040]

According to the magnetic sensor of the present invention, in a magnetic sensor arranged in a magnetic circuit through which a magnetic flux generated by a device to be protected or its peripheral device passes, a plurality of magnets are arranged so that the same poles face each other. Thus, a balanced position of the magnetic flux at which the magnetic flux density between the magnets becomes substantially 0 is set in advance to a predetermined offset amount from the position of the magnetoelectric conversion element, and the target device or its peripheral device is operated when the target device is operating. The balance of the magnetic flux of the magnet with respect to the magneto-electric conversion element is adjusted so that the position where the magnetic flux density between the magnets becomes substantially zero is moved to or near the magneto-electric conversion element by synthesizing the steady magnetic flux generated. ing. Therefore, when the magnetic sensor is mounted in the vicinity of a peripheral device that generates a predetermined magnetic field, it receives a leakage magnetic flux, so that the magnetic flux balanced position of the magnetic sensor can be set to a position on or near the magnetoelectric conversion element. Therefore, even if there is a device or the like that generates a strong magnetic field in the vicinity, it is possible to use a magnetoelectric conversion element that operates in a range where the magnetic flux density is relatively low, such as a Hall IC, for example. The influence can be substantially ignored and a signal can be output reliably due to the close proximity of the magnetic material.

The orthogonal magnetic flux component of the magnetic flux generated by the device to be protected or its peripheral device on the detection surface of the magneto-electric conversion element of the magnetic circuit changes the magnetic flux density passing through the magneto-electric conversion device in conjunction with the operation of the device to be protected. When the device to be protected is operating, the change in magnetic flux density due to the magnetic sensor itself and the change in magnetic flux density due to the magnetic circuit can be superimposed. Can be made larger and the operation as a sensor can be facilitated.

Further, by adopting a structure in which a plurality of magnets substantially cancel out magnetic fluxes perpendicular to the magneto-electric conversion element, the strength of the single magnet is not particularly a problem, so that selection of the magnet is easier than in the conventional case. Can be. Also, by using a strong magnet such as a rare-earth magnet, the rate of change in magnetic flux density between magnets, especially in the vicinity of 0 gauss, which is the detection area of the magnetic sensor, can be increased, thereby increasing the sensitivity as a sensor. Can also downsize the magnetic sensor.

[Brief description of the drawings]

FIG. 1 shows an embodiment of a magnetic sensor according to the present invention.

FIG. 2 is a characteristic diagram of a magnetoelectric conversion element used for the magnetic sensor of the present invention.

FIG. 3 is a characteristic diagram showing a relationship between a distance between a magnetic sensor and a detection target and a magnetic flux density passing through a magnetoelectric conversion element.

FIG. 4 is a partial sectional view showing a state where the magnetic sensor of FIG. 1 is attached to a compressor for a car air conditioner.

FIG. 5 is a magnetic characteristic diagram for explaining the operation of the magnetic sensor.

FIG. 6 is a schematic diagram for explaining FIG. 5;

FIG. 7 is a partially enlarged view showing a state where another embodiment of the present invention is attached to a compressor for a car air conditioner.

[Explanation of symbols]

1: Magnetic sensor 2: Hall IC (Magnetoelectric conversion element) 3A, 3B: Magnet (magnet for generating magnetic field) 4A, 4B: Iron core 5: Auxiliary iron core 6: Case 7: Filler 13: Magnet for generating magnetic field 201: Car air conditioner Compressor (protection target equipment) 207: Oldham ring (detection target)

Claims (3)

[Claims] 1. A device for protection or a peripheral device thereof, which is disposed in a magnetic circuit through which a magnetic flux generated by the device passes and has a magnet for generating a magnetic field and a magnetoelectric transducer, wherein the magnetic flux of the magnetic circuit is detected by the magnetoelectric transducer. In a magnetic sensor having an orthogonal magnetic flux component in a plane and detecting a change in a magnetic field due to proximity and separation of a magnetic body, the magnet generates a magnetic flux having a strength enough to cause an output change to a magnetoelectric conversion element. The magnets are composed of at least two magnets, and the magneto-electric conversion elements are arranged so as to be sandwiched in the detection direction and are arranged so that the same poles face each other. The equilibrium position of the magnetic flux at which the orthogonal magnetic flux component density on the surface is substantially zero is set in advance to a predetermined offset amount from the position of the magnetoelectric conversion element, and the target device is protected when the target device is operating. The magnetic flux generated by the magnet or its peripheral device is stationary, and by synthesizing this magnetic flux, the position where the magnetic flux density between the magnets becomes almost zero is moved to or near the detection surface of the magnetoelectric conversion element. A magnetic sensor wherein the magnetic flux is changed to a position where the magnetic flux of the magnet is balanced with the magnetoelectric conversion element as much as possible. 2. The orthogonal magnetic flux component of the magnetic flux generated by the device to be protected or its peripheral device on the detection surface of the magneto-electric conversion element of the magnetic circuit is linked to the magnetic flux density passing through the magneto-electric conversion element in conjunction with the operation of the device to be protected. 2. The magnetic sensor according to claim 1, wherein the magnetic sensor changes. 3. A main body having a magnetoelectric conversion element, and a separate magnet for generating a magnetic field, wherein the magnet is attached to an operating portion of a device to be protected, and a change in magnetic flux density due to proximity and separation of the magnet. In a magnetic sensor that detects
The sensor body is arranged in a magnetic circuit through which a magnetic flux generated by the device to be protected or its peripheral device passes, and the magnetic circuit changes the magnetic flux density passing through the magnetoelectric conversion element with the operation of the device to be protected. A magnetic sensor, wherein the generating magnet is attached to the magnetoelectric conversion element so as to generate a magnetic flux in a direction substantially canceling a magnetic flux component orthogonal to a detection surface of the magnetoelectric conversion element by the magnetic circuit.