JP4252868B2 - Non-contact position sensor - Google Patents

Description

  The present invention relates to a non-contact type position sensor that detects linear displacement and rotational displacement in a non-contact manner.

  FIG. 5A shows an example of a conventional configuration of a position sensor that detects a displacement position of a linearly displaced movable body as an example of this type of non-contact type position sensor. In this example, a pair of movable sensors (sliders) 11 are paired with each other. Magnets (permanent magnets) 12 and 13 are attached, and cores 14 and 15 made of a soft magnetic material and a magnetic sensor 16 are arranged on the fixed side with respect to the movable body 11.

  The core 14 is formed in a U shape, and both leg portions 14 a and 14 b of the U shape are arranged in the displacement direction of the movable body 11 (indicated by arrows in the figure). The core 15 is disposed with a predetermined gap therebetween. The front end surfaces of both leg portions 14a and 14b of the core 14 and the outer surface of the core 15 are located on the same plane.

  The pair of magnets 12 and 13 are formed in a plate shape and arranged in the displacement direction of the movable body 11, and are displaced in close proximity to the cores 14 and 15 as the movable body 11 is displaced. . These magnets 12 and 13 are magnetized in directions opposite to the cores 14 and 15, that is, in opposite directions in the plate thickness direction.

  The magnetic sensor 16 is located in a gap 17 between the inner surface of the core 15 and the U-shaped intermediate portion 14 c of the core 14, and detects the strength of the magnetic field between the cores 14 and 15 in the gap 17. Is done. The magnetic sensor 16 is, for example, a Hall IC configured using a Hall element.

  According to the position sensor 18 configured as described above, when the magnets 12 and 13 are located at the center of the cores 14 and 15, the magnetic flux passing through the magnetic sensor 16 becomes 0. When the magnets 12 and 13 are displaced from the center, the magnetic flux passes through the magnetic sensor 16. The direction of magnetic flux passing through the magnetic sensor 16 and the magnetic flux density change according to the displacement position of the movable body 11, and the magnetic sensor 16 outputs a voltage according to the change of the magnetic field. Therefore, the linear displacement position of the movable body 11 can be detected by the change in the output voltage (see, for example, Patent Document 1).

  On the other hand, FIG. 6A shows an example of a conventional configuration of a non-contact type position sensor that detects the rotational displacement position (rotation angle) of the rotation shaft. In this example, the displacement side core 21 and the rotation shaft (not shown) are connected to the rotation shaft. A pair of magnets 22 and 23 are attached, and a pair of fixed-side cores 24 and 25 and a magnetic sensor 26 are arranged on the fixed side with respect to the rotating shaft.

  The displacement-side core 21 has a cylindrical shape centered on the axis of the rotation shaft, and a pair of semi-cylindrical magnets 22 and 23 are arranged on the inner peripheral surface of the displacement-side core 21 so as to form a cylinder as a whole. ing. These magnets 22 and 23 are magnetized in directions opposite to each other in the radial direction of the cylinder. The displacement-side core 21 and the pair of magnets 22 and 23 are attached to the tip of the rotating shaft via an attachment member (attachment plate) or the like.

  The fixed-side cores 24 and 25 are positioned in a cylinder formed by the magnets 22 and 23, and each of the fixed-side cores 24 and 25 has a semi-columnar shape, and a predetermined gap is provided between the peripheral surface and the inner peripheral surfaces of the magnets 22 and 23. ing. The fixed cores 24 and 25 are opposed to each other via a gap 27 extending in the radial direction, and a magnetic sensor 26 is positioned in the gap 27. The magnetic sensor 26 is the same as the magnetic sensor 16 described above, and both the displacement side core 21 and the fixed side cores 24 and 25 are made of a soft magnetic material.

According to the position sensor 28 shown in FIG. 6A, the displacement side core 21 and the magnets 22 and 23 rotate around the fixed side cores 24 and 25 along with the rotation of the rotation shaft, and the magnetic field rotates. , The magnetic flux passing through the magnetic sensor 26 changes. Therefore, the rotational displacement position of the rotating shaft can be detected by the change in the output voltage of the magnetic sensor 26 (see, for example, Patent Document 2).
JP 2001-74409 A Japanese Patent No. 2920179

  As described above, the conventional non-contact type position sensor can detect the displacement position of the movable body in a non-contact manner by detecting the displacement of the movable body by the change of the magnetic field. There is a limit to the amount of displacement that can be detected, and there is a problem that the detection range cannot be made large.

  That is, in the position sensor 18 for detecting the linear displacement shown in FIG. 5A, the magnets 12 and 13 move rightward from the state where they are located at the center with respect to the cores 14 and 15, that is, move toward the leg 14b of the core 14. Accordingly, the magnetic flux passing through the magnetic sensor 16 gradually increases from 0, and when the magnet 13 comes to the right end facing the leg portion 14b, the magnetic flux becomes maximum. On the other hand, when the magnets 12 and 13 are moved to the left, that is, in the direction of the legs 14a of the core 14, the direction of the magnetic flux passing through the magnetic sensor 16 is opposite to that when moving to the right and moves. Accordingly, the magnetic flux passing through the magnetic sensor 16 gradually increases. When the magnet 12 comes to the left end facing the leg portion 14a, the magnetic flux becomes maximum.

FIG. 5B shows the relationship between the output of the position sensor 18 and the displacement amount due to such a change in magnetic flux, and the detectable displacement amount is 2L (−L to + L).
Here, a both L ₁ legs 14a, 14b of the length of the displacement direction of the core 14 of the movable member 11, the length L ₂ of the core 15, when both L ₃ the length of the magnet 12, 13, In order to obtain good detection sensitivity, these are for example
L ₁ = L ₂ = L ₃
L ₃ ≒ 2L
That is, in this case, the detectable amount of displacement is about the length of each of the magnets 12 and 13.

On the other hand, FIG. 6B shows the relationship between the output of the position sensor 28 for detecting the rotational displacement shown in FIG. 6A and the displacement amount (rotation angle), and the detectable rotation angle is 180 ° (−90 ° to +90). °) or less.
In view of such a situation, an object of the present invention is to provide a non-contact type position sensor capable of increasing the detection range as compared with the prior art and capable of detecting a wide range of displacement.

  According to the first aspect of the present invention, the non-contact type position sensor that detects the displacement position of the movable body in a non-contact manner is movable on the fixed side with respect to the movable body, the ring-shaped magnet attached to the movable body and displaced together with the movable body. A core made of a soft magnetic material that is arranged extending in the body displacement direction and forms a cylindrical outer peripheral surface as a whole, and is divided into two by a helical slit around the axis of the cylinder, and the slit The ring-shaped magnet has one semicircular part and the other semicircular part of the ring magnetized in opposite directions in the radial direction, and the outer peripheral surface of the core is sandwiched through a predetermined gap. It is assumed that it is arranged to surround.

  According to the second aspect of the present invention, the non-contact type position sensor for detecting the displacement position of the movable body in a non-contact manner is a magnet attached to the movable body and displaced together with the movable body, and the movable body on the fixed side with respect to the movable body. A core made of a soft magnetic material which is arranged extending in the displacement direction and has a cylindrical shape as a whole and divided into two by two opposing spiral slits around the axis of the cylinder, and the slit The magnet is formed in a ring shape or a cylindrical shape, and one semicircular portion and the other semicircular portion are magnetized in opposite directions in the radial direction, and the core It is assumed that it is located in a cylinder formed through a predetermined gap from the inner peripheral surface of the core.

  In the invention of claim 3, in the invention of claim 1 or 2, the movable body is assumed to be rotationally displaced, and the core is extended so as to form an arc.

  According to the present invention, in a position sensor that detects a displacement position of a movable body in a non-contact manner using a change in a magnetic field, the amount of displacement that can be detected can be greatly increased compared to the conventional case, and a wide range of displacement detection is possible. It becomes.

The best mode for carrying out the present invention will be described by way of example with reference to the drawings.
FIG. 1 shows a configuration of a position sensor that detects a displacement position of a linearly movable body as an embodiment of a non-contact position sensor according to the present invention. In this example, the position sensor 30 is a fixed core 31. , 32, a magnetic sensor 33, a separator 34, a magnet 35, and a displacement side core 36. In addition, illustration of a movable body is abbreviate | omitted.

  The fixed-side cores 31 and 32 constitute a cylindrical outer peripheral surface as a whole, and are divided into two by a spiral slit 37 around the axis of the cylinder. It is extended | stretched and arrange | positioned in the displacement direction (it shows with an arrow in a figure). In this example, the fixed-side cores 31 and 32 have a cylindrical shape as a whole, and are divided by two spiral slits 37 facing each other.

  The magnetic sensor 33 is accommodated and disposed in one slit 37 on one end side of the fixed cores 31 and 32, and a separator 34 is disposed in the other slit 37 and in both slits 37 on the other end side. Yes. In this example, the fixed cores 31 and 32 are fixedly integrated with each other while maintaining a slit 37 with a predetermined gap by a total of three separators 34 disposed at both ends thereof.

  The displacement-side core 36 has a ring shape, and a ring-shaped magnet 35 is fixedly disposed on the inner peripheral surface of the displacement-side core 36. In the magnet 35, one semicircular portion and the other semicircular portion of the ring are magnetized in opposite directions in the radial direction.

  The magnet 35 integrated with the displacement side core 36 is inserted by the fixed side cores 31 and 32 and is positioned so as to surround the fixed side cores 31 and 32, and the outer peripheral surface of the fixed side cores 31 and 32 and the magnet 35. Is opposed to the inner peripheral surface of the first through a predetermined gap 38. Thus, the magnet 35 integrated with the displacement side core 36 and positioned around the fixed side cores 31 and 32 is attached to a movable body that is linearly displaced, and maintains a predetermined gap 38 with the fixed side cores 31 and 32. It is assumed that it is linearly displaced with the movable body.

  In the above-described structure, the fixed side cores 31 and 32 and the displacement side core 36 are both made of a soft magnetic material, and for example, silicon steel or the like is used as the material. The magnet 35 is, for example, a bonded magnet, and powder of samarium cobalt or ferrite is used as the permanent magnet powder mixed with the resin. The separator 34 is made of a nonmagnetic material.

  The magnetic sensor 33 is, for example, a Hall IC configured using a Hall element, and detects a change in the magnetic field between the fixed cores 31 and 32 in the slit 37. In the figure, 33a indicates a terminal. The fixed cores 31 and 32 are not shown in the figure, but are fixed to a housing or the like.

  FIG. 2 shows magnetic flux lines (shown by dotted lines) formed by the magnet 35. The magnet 35 is displaced together with the movable body, and moves in the extending direction of the fixed cores 31 and 32, thereby forming a spiral shape. The magnetic flux passing through the slit 37 formed to change is changed.

  FIG. 2A shows a state in which the magnet 35 is located substantially in the center in the extending direction (axial direction) of the fixed cores 31 and 32. In this state, the magnetic flux passing through the slit 37 is zero. FIG. 2B shows a state when the magnet 35 is located to the left of the center in FIG. 1A. In this state, the magnetic flux passes through the slit 37 as shown in the drawing.

  In this example, the spiral slit 37 has a magnetic flux passing through the magnetic sensor 33 so that the magnetic flux passing through the slit 37 is maximized when the magnets 35 are positioned at both ends of the stationary cores 31 and 32 in the extending direction. In other words, that is, the magnet 35 when the magnet 35 is positioned at the right end of the fixed cores 31 and 32 and the magnet 35 when the magnet 35 is positioned at the left end. Between the center of the width of 35, the spiral of the slit 37 is rotated 180 ° around the axis.

  With such a configuration, the direction of magnetic flux passing through the magnetic sensor 33 and the magnetic flux density change according to the displacement over the entire length of the fixed cores 31 and 32 of the magnet 35, and the magnetic sensor 33 responds to the change of the magnetic field. The linear displacement position of the movable body to which the magnet 35 is attached can be detected by the change in the output voltage of the magnetic sensor 33.

  According to the position sensor 30 having the above-described configuration, the amount of displacement that can be detected is the length obtained by subtracting the width of the magnet 35 from the length of the fixed cores 31 and 32, and thus the conventional position shown in FIG. 5A. Compared with the sensor 18, the detection range can be greatly increased. For example, the detection range can be about 20 times the width of the magnet 35.

Next, an embodiment of the position sensor according to the present invention which can detect the rotational displacement position (rotation angle) of the movable body that is rotationally displaced will be described with reference to FIG.
The position sensor 40 shown in FIG. 3 is obtained by extending the fixed cores 31 and 32 in the position sensor 30 shown in FIG. 1 so as to form an arc. In this example, the center angle of the arc is about 270 °. In other words, the fixed-side cores 31 and 32 constitute approximately 3/4 arcs.

  The displacement-side core 36 and the magnet 35 integrated in a ring shape are attached to a movable body (not shown) that is rotationally displaced, and the magnet 35 maintains a predetermined gap 38 with the fixed-side cores 31 and 32. It is assumed to be rotationally displaced. For example, when the rotationally movable body is a rotary shaft, the displacement-side core 36 may be directly fixed to the peripheral surface thereof, or may be attached via a required attachment member, for example.

  According to the position sensor 40 shown in FIG. 3, the detectable rotational displacement amount (rotation angle) is an angle corresponding to a length (arc) obtained by subtracting the width of the magnet 35 from the length of the fixed cores 31 and 32. Therefore, the detection range greatly exceeds the detection range of 180 ° or less in the conventional position sensor 28 shown in FIG. 6A. For example, by further extending the arc formed by the fixed side cores 31 and 32, the detection range is nearly 360 °. The detection range can be increased.

  In each of the position sensors 30 and 40 shown in FIGS. 1 and 3, the fixed-side cores 31 and 32 have a cylindrical shape as a whole, that is, have a hollow structure. The fixed cores 31 and 32 may have a columnar shape as a whole. In this case, the fixed cores 31 and 32 are divided by one spiral slit around the axis, and the inner surfaces are opposed to each other through the slit.

  4 is different from the position sensors 30 and 40 described above, the magnet 35 attached to the movable body and displaced together with the movable body is located inside the cylinder of the fixed side cores 31 and 32 having a cylindrical shape as a whole. The position sensor 50 is shown as a structure that undergoes linear displacement, and such a configuration can also be adopted.

  The magnet 35 is formed in a ring shape, and one semicircular portion and the other semicircular portion are magnetized in opposite directions in the radial direction, and a cylindrical shape formed by the outer peripheral surface and the fixed side cores 31 and 32 is formed. A predetermined gap 38 'is provided between the inner peripheral surface and the magnet 35 is linearly displaced while maintaining this gap 38'. The two slits 37 having a spiral shape dividing the fixed-side cores 31 and 32 into two are formed in the same manner as the slits 37 in FIG. A displacement side core 36 ′ formed is fixedly arranged.

  Also in the position sensor 50 shown in FIG. 4, the direction of magnetic flux passing through the magnetic sensor 33 and the magnetic flux density change according to the displacement of the magnet 35 attached to the movable body. A corresponding voltage is output, and the linear displacement position of the movable body can be detected by the change in the output voltage.

  In this example, a ring-shaped magnet 35 is disposed around a columnar displacement-side core 36 '. For example, the magnet 35 has a columnar shape and the displacement-side core 36' does not exist. Also good. In this case, as in the case of the ring shape, the magnet 35 has one semicircular part and the other semicircular part magnetized in opposite directions in the radial direction.

  In the above-described example, the magnetic sensor 33 has a structure that is disposed in one slit 37 on one end side of the fixed cores 31 and 32, and the magnetic sensor 33 is disposed at such a fixed core 31. , 32, but also in the slit 37 at the intermediate portion in the extending direction of the stationary cores 31, 32.

The number of magnetic sensors 33 arranged in the slit 37 is not limited to one, and a plurality of magnetic sensors 33 may be arranged. For example, the magnetic sensors 33 may be arranged at both ends of the fixed cores 31 and 32 in the extending direction. In this case, if the outputs of the plurality of magnetic sensors 33 are averaged to detect the displacement position, the detection accuracy can be improved.
In the above-described example, the magnet 35 is a single magnet whose magnetization direction is changed in the middle. However, the magnet 35 may be composed of two magnets whose magnetization directions are opposite to each other.

The figure which shows one Example of invention of Claim 1, A is a perspective view, B is a left view, C is a right view. The figure which shows a mode that the magnetic flux which passes the slit in the non-contact-type position sensor shown in FIG. 1 changes. A perspective view showing an embodiment of the invention of claim 3. The figure which shows one Example of invention of Claim 2, A is a perspective view, B is a left view, C is a right view. A is a perspective view showing a conventional configuration of a non-contact type position sensor that detects linear displacement, and B is a graph showing the relationship between the displacement and output. A is a perspective view showing a conventional configuration of a non-contact type position sensor that detects rotational displacement, and B is a graph showing the relationship between the displacement (rotation angle) and output.

Claims (3)

A sensor that detects a displacement position of a movable body in a non-contact manner,
A ring-shaped magnet attached to the movable body and displaced together with the movable body;
A soft magnet which is arranged on the fixed side with respect to the movable body so as to extend in the displacement direction of the movable body, forms a cylindrical outer peripheral surface as a whole, and is divided into two by a spiral slit around the axis of the cylinder A core made of material,
It consists of a magnetic sensor arranged in the slit,
The ring-shaped magnet is arranged so that one semicircle part and the other semicircle part of the ring are magnetized in opposite directions in the radial direction and surround the outer peripheral surface of the core with a predetermined gap. A non-contact type position sensor. A sensor that detects a displacement position of a movable body in a non-contact manner,
A magnet attached to the movable body and displaced together with the movable body;
The movable body is arranged on the fixed side with respect to the movable body so as to extend in the displacement direction of the movable body, forms a cylindrical shape as a whole, and is divided into two by two spiral slits facing each other around the axis of the cylinder. A core made of soft magnetic material;
It consists of a magnetic sensor arranged in the slit,
The magnet has a ring shape or a columnar shape, and one semicircle portion and the other semicircle portion are magnetized in opposite directions in the radial direction, and the core is formed in a cylinder formed by the core. A non-contact type position sensor, wherein the position sensor is positioned via a predetermined gap from an inner peripheral surface. The non-contact position sensor according to claim 1 or 2,
The movable body is assumed to be rotationally displaced,
The non-contact type position sensor, wherein the core is extended so as to form an arc.

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