JP7144248B2 - Magnetic displacement detector that can reduce detection error - Google Patents

Description

The present invention relates to a magnetic displacement detector capable of reducing detection errors.

In machine tools, forging machines, injection molding machines, industrial machines, or robots, there are shafts of tools and hands, and sensors connected to the tools and hands to detect the actual positions of the tools and hands. A magnetic displacement detector is attached to detect the angle and position of the motor shaft. Magnetic displacement detectors include an angle detector that acquires information (angle, angular velocity, etc.) related to the rotational displacement of a rotating shaft, and a linear position detector that acquires information (position and velocity) related to linear displacement of a linear motor shaft. There are utensils.

In a magnetic displacement detector, the magnetic flux density of a body to be detected that is fixed to an object (hereinafter referred to as the "object") whose displacement is to be detected, such as a motor or shaft, is detected by the detection body, and the detected Displacement information such as angle, angular velocity, position, and velocity is obtained based on the change in magnetic flux density. For attaching the detection object to the object such as the motor or the shaft, for example, fixation by tightening screws or fixation by shrinkage fitting is used. If you want to avoid the effects of dimensional errors on the object, or if the object is large and difficult to shrink fit, place a They are often fixed with screws. Further, in order to avoid the influence of shaft deflection, the magnetic flux density of the object to be detected may be detected by a plurality of detection objects.

For example, a rotating part that rotates around the central axis of the motor together with the motor rotor, a detecting part that detects the rotational position of the rotating part, and a rotor hollow part that extends concentrically from one shaft end face of the motor rotor. and a bracket protruding into the rotor hollow portion from a portion of the motor housing facing the shaft end face,
The rotating part is fixed to the motor rotor inside the rotor hollow part,
The detection unit is fixed to the bracket in a state in which the detection unit is opposed to the rotation unit in the motor radial direction inside the rotor hollow portion,
The rotating part is a magnet having a circular outer peripheral surface that is multipolarized along the circumferential direction,
The magnet is coaxially fixed to the motor rotor inside the rotor hollow portion,
The detection unit is a plurality of magnetic detection elements arranged at regular intervals with respect to the circular outer peripheral surface of the magnet,
The rotor hollow portion has a large-diameter hollow portion on the rear side of the shaft end face side and a small-diameter hollow portion on the front side. The rear end face protrudes into the large-diameter hollow portion, and the magnet is fixed to the rear end face,
The bracket is coaxially fixed to an annular member fixed to the rear side end plate of the motor housing and to the front side of this annular member, and is installed inside the large-diameter hollow portion of the rotor hollow portion from the rear side. a projecting cylindrical member and a retaining member coaxially fixed to the front side of the cylindrical member, the retaining member having a forwardly open cylindrical portion coaxially surrounding the magnet. and
There is known a rotational position detector for a motor, characterized in that the magnetic detection elements are attached at predetermined angular intervals along the circumference of the inner peripheral surface of the cylindrical portion (for example, , see Patent Document 1).

For example, a rotational position detection magnet for detecting rotation angle information, a magnetic pole position detection magnet for detecting the energized position of the drive coil of the motor, and is fixed, the position detecting magnet and the magnetic pole position detecting magnet are aligned with respect to one rotating base fixed to the rotating shaft in a magnetic pole positional relationship with each other A magnetic encoder device is known which is characterized by being mounted integrally (see, for example, Patent Document 2).

Japanese Patent No. 4964303 Japanese Patent Application Laid-Open No. 2001-004405

A magnetic displacement detector obtains displacement information such as angle, angular velocity, position, or speed based on changes in the magnetic flux density of an object to be detected that is fixed to an object such as a motor or shaft. When the object and the object to be detected are fixed by screwing, stress is applied to the fixing part of the object to be detected by screwing, and the magnetic flux density is distorted. For this reason, in the object to be detected, the distortion of the magnetic flux density is greater in the screw-mounted portion than in the non-screw-mounted portion. Distortion of the magnetic flux density generated in the screw mounting portion of the object to be detected affects the detection accuracy of the magnetic displacement detector. In particular, in a magnetic displacement detector configured to detect the magnetic flux density of an object to be detected by a plurality of detection bodies in order to avoid the influence of shaft deflection, the distortion of the magnetic flux density is detected by the plurality of detection bodies. Therefore, the detection error of the magnetic displacement detector becomes larger. Therefore, in the magnetic displacement detector that obtains the displacement information of the object by detecting the magnetic flux density of the object to be detected that is fixed to the object via the fastener, the effect of the fastener on the detection error is reduced. A technology to

According to one aspect of the present disclosure, a magnetic displacement detector that detects displacement of an object includes a detection object fixed to the object and a change in magnetic flux density caused by movement of the detection object. and a plurality of detection bodies that individually output signals corresponding to the positions of the detection bodies, and each of the plurality of detection bodies has a magnetic flux density detection range of at least one of the plurality of detection bodies. It is arranged so that the region of the detection body that is not fixed to the object is positioned.

Further, according to one aspect of the present disclosure, the magnetic displacement detector that detects the displacement of the object is a plurality of detected objects fixed to the object, wherein the detected objects and the object are the first and a second fastener between each of the objects to be detected. and a plurality of detection bodies that individually output signals corresponding to the positions of the detection bodies, and each of the plurality of detection bodies is within the magnetic flux density detection range of at least one detection body among the plurality of detection bodies. A region that is not fixed to the object or a region that includes the mounting portion of the first fastener in the detected object is positioned.

According to one aspect of the present disclosure, in a magnetic displacement detector that obtains displacement information of an object by detecting the magnetic flux density of an object to be detected that is fixed to the object via a fastener, the fastener The influence on detection error can be reduced.

1 is a schematic diagram of a magnetic displacement detector according to a first embodiment of the present disclosure; FIG. 1 is a diagram showing a magnetic displacement detector according to a first embodiment of the present disclosure, where (A) is an exploded perspective view showing the relationship between an object to be detected and an object, and (B) is a signal processing unit; 1 is a schematic perspective view of a magnetic displacement detector including; FIG. 1 is a schematic diagram of a conventional magnetic displacement detector; FIG. FIG. 4 is a schematic diagram illustrating a case where three detection bodies are provided in the magnetic displacement detector according to the first embodiment of the present disclosure; FIG. 4 is a schematic diagram of a magnetic displacement detector according to a second embodiment of the present disclosure; FIG. 10 is a diagram showing a magnetic displacement detector according to a second embodiment of the present disclosure, where (A) is an exploded perspective view showing the relationship between an object to be detected and an object, and (B) is a signal processing unit; 1 is a schematic perspective view of a magnetic displacement detector including; FIG. FIG. 10A is a schematic diagram and FIG. 1B is a perspective view showing another example of the arrangement of the detection bodies according to the second embodiment of the present disclosure; FIG. 4 is a schematic diagram of a magnetic displacement detector according to a third embodiment of the present disclosure; FIG. 10 is a diagram showing a magnetic displacement detector according to a third embodiment of the present disclosure, where (A) is an exploded perspective view showing the relationship between an object to be detected and an object, and (B) is a signal processing unit; 1 is a schematic perspective view of a magnetic displacement detector including; FIG. FIG. 5 is a schematic diagram of a magnetic displacement detector according to a fourth embodiment of the present disclosure;

A magnetic displacement detector capable of reducing detection errors will be described below with reference to the drawings. In order to facilitate understanding, the scales of these drawings are appropriately changed. The form shown in the drawings is an example of implementation and is not limited to the illustrated embodiment.

Specific examples of objects whose displacement is detected by the magnetic displacement detector according to the embodiment of the present disclosure include machine tools, forging machines, injection molding machines, industrial machines, shafts of tools and hands such as robots, and motors. , etc. Some embodiments of the magnetic displacement detector are listed below. In the following embodiments, screws, for example, are used as fasteners for fixing the detected body and the object and as fasteners for fixing the detected bodies to each other. Alternatively, the fasteners for fixing the object to be detected and the object to be detected and the fasteners for fixing the objects to be detected may be fasteners having a pressing mechanism other than screws.

1 is a schematic diagram of a magnetic displacement detector according to a first embodiment of the present disclosure; FIG. 2A and 2B are diagrams showing the magnetic displacement detector according to the first embodiment of the present disclosure, in which (A) is an exploded perspective view showing the relationship between an object to be detected and an object; ) is a schematic perspective view of a magnetic displacement detector including a signal processing unit. A magnetic displacement detector 1 according to the first embodiment of the present disclosure is an angle detector that acquires information about rotational displacement of a rotating motor, shaft, or the like.

A magnetic displacement detector 1 for detecting the displacement of an object 2 includes a detection object 11, a plurality of detection objects 12-1 and 12-2, and a signal processing section 13. FIG.

The object 11 to be detected is fixed to the object 2 and moves integrally with the object 2 . For example, a screw 21 is used as a fastener for fixing the object 11 to be detected and the object 2 . That is, the detected object 11 is fixed to the object 2 by fastening the screw 21 . FIG. 1 shows the axial end face of the detected body 11 (the end face facing the axial direction of the rotating shaft 100 of the detected body 11). As shown in FIG. 2, the object to be detected 11 is directly fixed to the object 2 via a screw 21. may be indirectly fixed via screws 21 to the .

The object 11 to be detected is, for example, a magnetic drum having a cylindrical shape. Alternatively, the detected body 11 may be, for example, a sensor gear. A track portion 41 having an uneven shape like a tooth portion of a gear is provided on the cylindrical circumferential surface of the detection object 11 . Since the track portions 41 have an uneven shape, the magnetic flux densities detected by the detection bodies 12-1 and 12-2, which will be described later, vary according to the shape of the track portions 41. FIG.

A screw hole 31 is provided in the end surface of the cylindrical shaft of the object 11 to be detected. In addition, on the shaft end surface of the object 2, in positions corresponding to the respective screw holes 31 of the object 11, so that the rotation axis 100 of the object 2 and the rotation axis 100 of the object 11 are aligned. A screw hole 32 is provided. The screw 21 passes through the screw hole 31 of the detection object 11 and the screw hole 32 of the object 2 and is fastened, so that the detection object 11 and the object 2 are connected while having a common rotation axis 100 . can be fixed.

The detection bodies 12-1 and 12-2 detect changes in the magnetic flux density accompanying the rotation of the detection body 11 and individually output signals corresponding to the position of the detection body 11. FIG. The detection bodies 12-1 and 12-2 are arranged side by side in the circumferential direction so as to face the cylindrical circumferential surface of the detection target body 11. As shown in FIG. The detection bodies are arranged such that a line connecting the detection bodies 12-1 and 12-2 is along the diameter direction of the cylindrical shape of the detection body 11. FIG. In the embodiment shown in FIGS. 1 and 2, the number of detection bodies is two as an example, but the number may be three or more. Therefore, the "detection bodies 12-1 and 12-2" described here can be read as "a plurality of detection bodies".

Specific examples of the detection bodies 12-1 and 12-2 include a magnetic sensor that measures the magnetic flux density using the Hall effect of a Hall element, and a magnetic resistance element that changes the resistance value depending on the magnetic flux density. There are magnetic sensors that output , magnetic sensors that use electromagnetic induction of coils, and the like. Regardless of which form of magnetic sensor the detection bodies 12-1 and 12-2 are composed of, the magnetic sensor generally has a range in which the magnetic flux density can be detected (referred to as a "magnetic flux density detection range"). . In the magnetic displacement detector 1, considering the magnetic flux density detection range of the detection bodies 12-1 and 12-2, the arrangement positions of the detection bodies 12-1 and 12-2 and the detection body 11 is determined.

At least one of the detection bodies 12-1 and 12-2 is detected at any time (moment) during the rotation of the detection target 11 (that is, the object 2). A non-fixed portion (that is, a region that does not include the screw 21 attachment portion), which is a region of the detected body 11 that is not fixed to the object 2, is positioned within the magnetic flux density detection range of the body. A portion of the object 11 to be fixed to the object 2, that is, “a region including a mounting portion of the screw 21” is a region where the object 11 is pressed against the object 2 by the screw 21, and is therefore called a “holding portion”. be able to. In addition, in the non-fixed portion, that is, the “area not including the mounting portion of the screw 21 ”, which is the area of the object 11 to be detected that is not fixed to the object 2 , the object 11 is not pressed against the object 2 by the screw 21 . Since it is a region, it can be called a "non-pressing portion". In the detected object 11 , the portion where the screw 21 is attached for fixing to the object 2 has a larger distortion in the magnetic flux density than the portion other than the portion where the screw 21 is attached. In this embodiment, during the rotation of the detected body 11 (that is, the object 2), the magnetic flux density detection range of one of the detected bodies 12-1 and 12-2 includes the mounting portion of the screw 21. When the area is positioned, the non-fixed part (area not including the mounting part of the screw 21), which is not a fixed part to the object 2, is positioned in the magnetic flux density detection range of the other detection body. . As described above, the detection bodies 12-1 and 12-2 are provided to avoid the influence of the vibration of the rotating shaft 100 of the object 2. FIG. "At any time during the rotation of the detection object 11 (that is, the object 2), the magnetic flux density detection range of at least one detection object has a non-fixed area, which is a portion of the detection object 11 that is not fixed to the object 2. The positional relationship of "the part is located" should be satisfied between the detection bodies provided in order to avoid the influence of the vibration of the rotating shaft 100 of the object 2.

The object 11 to be detected is provided with a screw hole 31 as a mounting portion for a screw 21 for fixing to the object 2 . More specifically, the fixed part (area including the mounting part of the screw 21) of the detected body 11 to the object 2 is in the magnetic flux density detection range of one of the detected bodies 12-1 and 12-2. A non-fixed portion, which is a region of the detected body 11 that is not fixed to the object 2, is positioned within the magnetic flux density detection range of at least one of the detected bodies 12-1 and 12-2. , the object 11 to be detected is provided with a screw hole 31 into which the screw 21 that is a fixing portion to the object 2 is mounted. For example, FIG. 1 shows the position of the screw 21 of the object 11 to be detected at a certain point in time. In addition, the non-fixed portion (area not including the mounting portion of the screw 21), which is the region not fixed to the object 2 in the detected body 11, is positioned in the magnetic flux density detection range of the detected body 12-1. do.

For example, as shown in FIGS. 1 and 2, when the detection body 12-1 and the detection body 12-2 are provided so as to face each other along the diameter direction of the cylindrical shape of the detection body 11 If an odd number (seven in the example shown) of screw holes 31 are arranged on the axial end face of the object 11 to be detected at regular intervals along the circumference of the object 11, the rotation of the object 11 can be controlled. At any point in time, in the above-mentioned "magnetic flux density detection range of at least one of the detection bodies 12-1 and 12-2, in the area where the detection body 11 is not fixed to the object 2 A certain non-fixed portion (an area that does not include the mounting portion of the screw 21) is located” can be satisfied. When designing the magnetic displacement detector 1, considering the magnetic flux density detection range of the detection bodies 12-1 and 12-2 and the size of the screw 21, the screw hole provided on the axial end surface of the detection target body 11 Preferably, the number of 31 is determined. For example, when the magnetic flux density detection range of the detection bodies 12-1 and 12-2 is wide, the size of the fixed portion of the detection body 11 to the object 2 is reduced, or 2, it becomes easier to satisfy the above positional relationship. Further, for example, when the magnetic flux density detection range possessed by the detection bodies 12-1 and 12-2 is narrow, the fixing portion of the detection body 11 to the object 2 is increased, or By increasing the number of fixing portions, it becomes easier to satisfy the above positional relationship. The size of the fixed portion of the detected body 11 to the object 2 depends on the size of the screw 21 , and the number of fixed portions of the detected body 11 to the object 2 depends on the number of screw holes 31 .

According to the present embodiment, the number of detection objects that can detect the area including the mounting portion of the screw 21 with a distorted magnetic flux density during rotation of the detection object 11 is at most one. 21 on the detection error of the magnetic displacement detector is reduced. In this embodiment, during the rotation of the detection object 11, the non-fixed portion (screw 21 However, in this case, distortion of the magnetic flux density due to the mounting of the screw 21 does not occur in the region that does not include the mounting portion of the screw 21 in the first place. The detection error of the displacement detector 1 is not affected.

As described above, since the track portion 41 having an uneven shape is provided on the cylindrical circumferential surface of the detection object 11, the detection objects 12-1 and 12-2 can be detected by rotating the detection object 11. A change in the magnetic flux density corresponding to the shape of the track portion 41 is detected, and a signal corresponding to the position of the detected object 11 (a signal corresponding to the change in the magnetic flux density) is individually output. The detection bodies 12-1 and 12-2, for example, output a signal (electrical signal) having a larger amplitude as the detected magnetic flux density increases.

The signal processing unit 13 acquires the displacement information of the object 2 by arithmetic processing based on the signals output from the detection bodies 12-1 and 12-2. Note that the detection bodies 12-1 and 12-2 are provided as a set in order to avoid the influence of the vibration of the rotating shaft 100 of the object 2. A single displacement information of the object 2 is acquired based on the signals output from 1 and 12-2 respectively. The displacement information of the object 2 includes the rotation angle, rotation angular velocity, rotation angular acceleration, and the like of the object 2 . The signal processing unit 13 is configured by, for example, an arithmetic processing device having a CPU (Central Processing Unit). The signal processing unit 13 outputs the acquired displacement information of the object 2 to the external device 3 . For example, the external device 3 is a machine tool control device or a robot control device. The external device 3 can perform predetermined control based on the obtained displacement information of the object 2 .

FIG. 3 is a schematic diagram of a conventional magnetic displacement detector. FIG. 3 shows the axial end face of the detected body 111 (that is, the end face of the detected body 111 facing the axial direction of the rotating shaft 100). In the conventional magnetic displacement detector 101 provided with the detection bodies 112-1 and 112-2 to avoid the influence of the deflection of the rotation axis 100 of the object 2, the magnetic flux of both the detection bodies 112-1 and 112-2 When the area including the mounting portion of the screw 121 is positioned within the density detection range, the detection bodies 112-1 and 112-2 detect the magnetic flux density including the strain caused by the stress of the screw 121, and detect the magnetic flux density including the strain. A signal corresponding to the magnetic flux density is output to the signal processing unit 113 . The signal processing unit 113 acquires the displacement information of the object 2 by arithmetic processing based on the signal affected by the distortion of the magnetic flux density. Therefore, the detection error of the conventional magnetic displacement detector 101 becomes large. On the other hand, in the present embodiment, at any time during the rotation of the detection object 11, the magnetic flux density detection range of at least one detection object includes A certain non-fixed part is located. In other words, the number of detection objects that detect the magnetic flux density including the strain caused by the stress of the screw 21 during rotation of the detection object 11 is only one at most. The influence on the detection error of the magnetic displacement detector due to is reduced.

In the embodiment shown in FIGS. 1 and 2, the number of detection bodies is two as an example, but the number may be three or more. FIG. 4 is a schematic diagram illustrating a case where three detection bodies are provided in the magnetic displacement detector according to the first embodiment of the present disclosure. FIG. 4 shows the axial end face of the detected body 11 (that is, the end face of the detected body 11 facing in the axial direction of the rotating shaft 100). In the example shown in FIG. 4, detection bodies 12-1, 12-2 and 12-3 are provided in order to avoid the influence of vibration of the rotating shaft 100 of the object 2. FIG. Detection bodies 12-1, 12-2, and 12-3 are at least one of detection bodies 12-1, 12-2, and 12-3 at any time during rotation of detection object 11. The non-fixed portion (the region not including the mounting portion of the screw 21), which is the region of the detected body 11 that is not fixed to the object 2, is positioned within the magnetic flux density detection range of . For example, as shown in FIG. 4, an odd number (three in the illustrated example) of detection bodies 12-1, 12-2 and 12-3 are provided at equal intervals along the circumference of the detection body 11. In this case, if an even number (eight in the illustrated example) of screw holes 31 are arranged on the axial end face of the object 11 to be detected at equal intervals along the circumference of the object 11 to be detected, the above positional relationship can be achieved. meet.

FIG. 5 is a schematic diagram of a magnetic displacement detector according to a second embodiment of the present disclosure; 6A and 6B are diagrams showing a magnetic displacement detector according to a second embodiment of the present disclosure, in which (A) is an exploded perspective view showing the relationship between a body to be detected and an object; ) is a schematic perspective view of a magnetic displacement detector including a signal processing unit. A magnetic displacement detector 1 according to the second embodiment of the present disclosure is an angle detector that acquires information about rotational displacement of a rotating motor, shaft, or the like. FIG. 5 shows the axial end face of the detected body 11-2 (that is, the end face of the detected body 11 facing the axial direction of the rotating shaft 100).

In the second embodiment, two objects to be detected 11-1 and 11-2 are superimposed on the object 2 along the direction of the rotating shaft 100 and move integrally with the object 2. FIG. In the embodiment shown in FIGS. 5 and 6, the number of objects to be detected is two as an example, but the number may be three or more. Therefore, the "objects to be detected 11-1 and 11-2" described here can be read as "a plurality of objects to be detected". FIG. 5 shows the axial end face of the detected body 11-2 (that is, the end face of the detected body 11 facing the axial direction of the rotating shaft 100).

The object to be detected 11-1 and the object to be detected 11-2 are fixed by fastening screws 21. FIG. The objects 11-1 and 11-2 to be detected and the object 2 are fixed by fastening screws 22. FIG. The axial end faces of the objects to be detected 11-1 and 11-2 are provided with a screw hole where the screw 21 is mounted and a screw hole 33 where the screw 22 is mounted. A threaded hole 32, which is the mounting portion of 22, is provided.

The detection bodies 12-1 and 12-2 face the cylindrical circumferential surface of the detection body 11-1 (that is, the line connecting the detection bodies 12-1 and 12-2 is the detection body 11) and along the circumferential direction. The detection bodies 12-1 and 12-2 detect changes in the magnetic flux density accompanying the rotation of the detection body 11-1, and generate signals corresponding to the position of the detection body 11 (signals corresponding to changes in the magnetic flux density). Output them individually. Further, the detection bodies 12-5 and 12-6 face the cylindrical circumferential surface of the detection body 11-1 (that is, the line connecting the detection bodies 12-5 and 12-6 (along the diameter direction of the cylindrical shape of the detection body 11) and along the circumferential direction. The detection bodies 12-5 and 12-6 detect changes in the magnetic flux density accompanying the rotation of the detection body 11-2, and generate signals corresponding to the position of the detection body 11 (signals corresponding to changes in the magnetic flux density). Output them individually. Specific examples of the detection bodies 12-1, 12-2, 12-5, and 12-6 are as described in the first embodiment.

The objects to be detected 11-1 and 11-2 are, for example, cylindrical magnetic drums. Alternatively, the objects to be detected 11-1 and 11-2 may be sensor gears, for example. A track portion 41 having an uneven shape like a tooth portion of a gear is provided on the cylindrical circumferential surface of the object 11-1 to be detected. Since the track portion 41 has an uneven shape, the magnetic flux densities detected by the detection bodies 12-1 and 12-2 change according to the shape of the track portion 41. FIG. Similarly, a track portion 42 is provided on the cylindrical circumferential surface of the detected body 11-2, and the track portion 42 has a concave or convex shape, so that the detected bodies 12-5 and 12-6 A change occurs in the magnetic flux density detected by , depending on the shape of the track portion 42 . The shape of the track portion 41 of the object to be detected 11-1 and the shape of the track portion 42 of the object to be detected 11-2 is merely an example. For example, if the track portion 42 of the object to be detected 11-2 also has an uneven shape and is configured to be out of phase with the uneven shape of the track portion 41 by 90 degrees, the detection object 12-1 and An A-phase signal and a B-phase signal can be output from 12-2 and detection bodies 12-5 and 12-6.

In the second embodiment, considering the magnetic flux density detection ranges of the detection bodies 12-1, 12-2, 12-5 and 12-6, for example, the detection bodies 12-1, 12- 2, 12-5 and 12-6, and the arrangement positions of the screws 21 and 22 on the detected bodies 11-1 and 11-2 should be designed.

For example, as shown in FIGS. 5 and 6, if the detection bodies 12-1 and 12-5, and the detection bodies 12-2 and 12-6 are arranged so as to overlap in the axial direction of the rotating shaft 100, each The positions of the detection bodies and the arrangement positions of the screws 21 and 22 in the detection bodies 11-1 and 11-2 can be designed in the same manner as in the first embodiment. That is, at any time during the rotation of the detection objects 11-1 and 11-2, the pair of the detection objects 12-1 and 12-5 and the detection objects 12-2 and 12-6 In the magnetic flux density detection range of at least one of the sets, the non-fixed portion (not including the mounting portion of the screws 21 and 22), which is the region that is not the fixed portion to the object 2 in the detected objects 11-1 and 11-2 Detecting bodies 12-1, 12-2, 12-5 and 2-6 are provided around the detected bodies 11-1 and 11-2 so that the regions) are positioned. As a result, the magnetic flux density detection range of any one of the set of the detection bodies 12-1 and 12-5 and the set of the detection bodies 12-2 and 12-6 is detected. When the regions (regions including the mounting portions of the screws 21 and 22) that are fixed portions to the countermeasure 2 in the bodies 11-1 and 1-2 are located, the set of the detection bodies 12-1 and 12-5 and a region of the detected bodies 11-1 and 11-2 which is not fixed to the object 2 in the magnetic flux density detection range of at least one set of the detected bodies 12-2 and 12-6. A non-fixed part is located.

Also, an example of arrangement of the detection bodies different from those in FIGS. 5 and 6 is conceivable. 7A and 7B are diagrams showing another example of the arrangement of the detection bodies according to the second embodiment of the present disclosure, where (A) is a schematic diagram and (B) is a perspective view. As shown in FIG. 7, along the diameter direction of the cylindrical shape of the detection object 11, the detection objects 12-1 and 12-2 face each other (that is, the detection objects 12-1 and 12-2 -2 is provided along the diameter direction of the cylindrical shape of the detection object 11) and the detection objects 12-5 and 12-6 face each other (that is, the detection object 12-5 and the detection body 12-6 is provided along the diameter direction of the cylindrical shape of the detection body 11). The set of the detection bodies 12-1 and 12-2 and the set of the detection bodies 12-5 and 12-6 are provided 90 degrees apart. An odd number of screws 21 and 22 in total are arranged on the axial end face of the object 11 to be detected at regular intervals along the circumference of the object 11 to be detected. As a result, the magnetic flux density detection range of one of the detection bodies 12-1 and 12-2, which is the fixed part of the detection body 11-1 with the object 2 (the attachment of the screws 21 and 22) When the magnetic flux density detection range of at least one of the detection bodies 12-1 and 12-2 is located, the area where the detection body 11-1 is not fixed to the object 2 is located. A certain non-fixed portion comes to be located. Similarly, when the area including the mounting portions of the screws 21 and 22 in the detected body 11-2 is positioned within the magnetic flux density detection range of either of the detected bodies 12-5 and 12-6, the detected body A non-fixed portion, which is a region of the detected object 11-2 that is not fixed to the object 2, is positioned within the magnetic flux density detection range of at least one of the detected objects 12-5 and 12-6.

In the second embodiment shown in FIGS. 5 to 7, the signal processing unit 13 performs arithmetic processing on the object 2 (detected object 11- 1) acquires the first information about the displacement, and based on the signals output by the detection bodies 12-5 and 12-6, performs arithmetic processing to obtain the second information about the displacement of the object 2 (detection body 11-2). Get information. The first information and second information regarding the displacement of the object 2 include the rotation angle, rotation angular velocity, rotation angular acceleration, or one-rotation signal of the object 2 . Depending on the type of displacement information of the object 2 to be acquired, the shape of the slit portion 41 provided in the detection object 11-1, the shape of the slit portion 42 provided in the detection object 11-2, and the signal processing unit 13 What is necessary is just to design the content of arithmetic processing suitably. The signal processing unit 13 is configured by, for example, an arithmetic processing device having a CPU (Central Processing Unit). The signal processing unit 13 outputs the acquired first and second information regarding the displacement of the object 2 to the external device 3 . For example, the external device 3 is a machine tool control device or a robot control device. The external device 3 can perform predetermined control based on the obtained first and second information regarding the displacement of the target object 2 .

FIG. 8 is a schematic diagram of a magnetic displacement detector according to a third embodiment of the present disclosure; 9A and 9B are diagrams showing a magnetic displacement detector according to a third embodiment of the present disclosure, in which (A) is an exploded perspective view showing the relationship between an object to be detected and an object; ) is a schematic perspective view of a magnetic displacement detector including a signal processing unit. A magnetic displacement detector 1 according to the third embodiment of the present disclosure is an angle detector that acquires information about rotational displacement of a rotating motor, shaft, or the like.

The third embodiment is a modification of the second embodiment. In the third embodiment, as in the second embodiment, two detection objects 11-1 and 11-2 are provided to overlap the object 2 along the direction of the rotation axis 100, and move together. In the third embodiment shown in FIGS. 8 and 9, the number of objects to be detected is two as an example, but the number may be three or more. Therefore, the "objects to be detected 11-1 and 11-2" described here can be read as "a plurality of objects to be detected". FIG. 8 shows the axial end face of the detected body 11-2 (that is, the end face of the detected body 11 facing the axial direction of the rotating shaft 100).

The screws 22 fix the objects 11-1 and 11-2 and the object 2 to be detected. For example, a threaded hole 32 (female thread) is formed by tapping as a portion for attaching the screw 22 to the object 2 . On the other hand, simple through-holes that are not tapped are formed in the objects to be detected 11-1 and 11-2 as mounting portions for the screws 22. As shown in FIG. If the screw 22 is passed through the through holes provided in the objects to be detected 11-1 and 11-2 and further tightened to the screw hole 32 provided in the object 2, the bearing surface of the head of the screw 22 is used to detect the object. The body 11-1 is pressed in the direction of the object 2, and the objects 11-1 and 11-2 to be detected and the object 2 can be fixed. At this time, since the screw 22 only passes through the through-holes of the objects to be detected 11-1 and 11-2, the area including the arrangement position of the screw 22 in the objects to be detected 11-1 and 11-2 is The distortion of the magnetic flux density is smaller than the distortion of the magnetic flux density in the area including the arrangement position (screw hole 32) due to the "fastening" of the screw 21 in the objects to be detected 11-1 and 11-2. In the third embodiment, in the magnetic flux density detection range of at least one of the set of the detection bodies 12-1 and 12-5 and the set of the detection bodies 12-2 and 12-6, " A non-fixed portion (a region that does not include the mounting portion of either the screw 21 or the screw 22), which is a region that is not fixed to the object 2 in the detected objects 11-1 and 11-2, or “the detected object 11-1 and Detecting bodies 12-1, 12-2, 12-5 and 12-6 are positioned around the detected bodies 11-1 and 11-2 so that a region including the mounting portion of the screw 22 in 11-2 is positioned. placed. In the magnetic flux density detection range of either one of the set of the detection bodies 12-1 and 12-5 and the set of the detection bodies 12-2 and 12-6, the screw 21 At the time when the area including the mounting portion is located, the magnetic flux density detection range of the other detection body includes "non-fixed area, which is the area that is not fixed to the object 2 in the detection objects 11-1 and 11-2. "part" or "area including the mounting part of the screw 22" is located. There is no magnetic flux density distortion in the "non-fixed portions, which are regions of the objects to be detected 11-1 and 11-2 which are not fixed to the object 2". Further, the distortion of the magnetic flux density is smaller in the "region including the mounting portion of the screw 22" than in the "region including the mounting portion of the screw 21". Therefore, the magnetic displacement detector 1 according to the third embodiment also reduces the influence of the screw 21 on the detection error of the magnetic displacement detector.

FIG. 10 is a schematic diagram of a magnetic displacement detector according to a fourth embodiment of the present disclosure; A magnetic displacement detector 1 according to the fourth embodiment of the present disclosure is a linear position detector that acquires information on linear displacement of the shaft of a linear motor or the like.

A track portion (not shown) having an uneven shape like a tooth portion of a gear is provided on the side surface of the object 11 to be detected, which is affirmed by the object 2 moving linearly. Since the track portions have an uneven shape, the magnetic flux densities detected by the detection bodies 12-1 and 12-2 change according to the shape of the track portions. A screw hole is provided by tapping from a surface of the object 11 to be detected, which is different from the side surface on which the track portion is provided, toward the surface with which the object 2 is in contact. The detection object 11 and the object 2 are fixed by fastening the screw 21 through the screw hole. Thereby, the detected object 11 linearly moves integrally with the object 2 .

The detection bodies 12-1 and 12-2 detect changes in the magnetic flux density accompanying the linear movement of the detection body 11, and individually output signals corresponding to the position of the detection body 11. FIG. The detection bodies 12-1 and 12-2 are arranged side by side in the linear movement direction of the detection body 11 fixed to the object 2 that moves linearly. In the embodiment shown in FIG. 10, the number of detection bodies is two as an example, but the number may be three or more. Therefore, the "detection bodies 12-1 and 12-2" described here can be read as "a plurality of detection bodies". Specific examples of the detection bodies 12-1 and 12-2 are as described in the first embodiment.

At any time during the linear movement of the detected object 11 (that is, the object 2), at least one of the detected objects 12-1 and 12-2 It is provided around the object 11 to be detected so that a region of the object 11 to be detected that does not include the mounting portion of the screw 21 is positioned within the magnetic flux density detection range. That is, when the area including the mounting portion of the screw 21 in the detected body 11 is positioned within the magnetic flux density detection range of one of the detected bodies 12-1 and 12-2, the detected body 12-1 and 12-2, so that an area not including the mounting portion of the screw 21 in the detection object 11 is positioned within the magnetic flux density detection range of at least one of the detection objects 12-2. A hole is provided.

In order that the above-described positional relationship between the detection bodies 12-1 and 12-2 and the area of the detection body 11 not including the mounting portion of the screw 21 is established at any time during the linear movement of the detection body 11, The positions of the detection bodies 12-1 and 12-2 and the arrangement positions of the screws 21 on the detection body 11 should be designed. For example, as shown in FIG. 10, when the detection body 12-1 and the detection body 12-2 are provided side by side along the linear movement direction of the detection body 11, the screw provided in the detection body 11 21 is sufficiently longer than "the length along the direction of linear movement of the object to be detected 11 with respect to the magnetic flux density detection range of the detection object 12-1 or 12-2", the position fulfill the relationship.

In the fourth embodiment, since the above-described positional relationship holds at any time during the linear movement of the detection object 11, the magnetic flux density of either one of the detection objects 12-1 and 12-2 is At the time when the area including the mounting portion of the screw 21 is positioned in the detection range, the area not including the mounting portion of the screw 21 is positioned in the magnetic flux density detection range of the other detection body. Therefore, even if the two detection bodies 12-1 and 12-2 detect the magnetic flux density of the detection target 11, the maximum number of detection bodies that detect the magnetic flux density including the distortion caused by the attachment of the screw 21 is one. Therefore, the influence of the screw 21 (fastener) on the detection error of the magnetic displacement detector is reduced as compared with the conventional example. In this embodiment, while the detection object 11 (that is, the object 2) is rotating, an area that does not include the mounting portion of the screw 21 is positioned in the magnetic flux density detection range of both the detection objects 12-1 and 12-2. However, in this case, distortion of the magnetic flux density due to the attachment of the screw 21 does not occur in the area not including the attachment portion of the screw 21, so the magnetic displacement detector by the screw 21 (fastener) does not occur. No effect on the detection error occurs in the first place.

1 Magnetic Displacement Detector 2 Object 3 External Device 11, 11-1, 11-2 Detected Object 12-1, 12-2, 12-3, 12-4, 12-5, 12-6 Detected Object 13 Signal processing unit 21, 22 Screw 31, 32 Screw hole 33 Through hole 41, 42 Track unit 100 Rotation shaft

Claims (9)

A magnetic displacement detector for detecting displacement of an object,
a detectable object fixed to the object;
a plurality of detection bodies that detect changes in magnetic flux density accompanying movement of the detection body and individually output signals corresponding to the positions of the detection bodies;
with
Each of the plurality of detection bodies is arranged such that a region of the detection body that is not fixed to the object is positioned within a magnetic flux density detection range of at least one of the plurality of detection bodies. ,
The fixing part includes a screw that is a fastener,
The object to be detected is a magnetic displacement detector fixed to the object by fastening the screw . at least one of the plurality of detection bodies when a portion fixed to the detection body of the detection body is positioned within a magnetic flux density detection range of any one of the plurality of detection bodies 2. The object to be detected is provided with a fixed portion to the object such that a region of the object to be detected that is not a fixed portion to the object is located in the magnetic flux density detection range of Magnetic displacement detector. The object to be detected has a cylindrical shape,
The cylindrical axial end face of the detected object is fixed to the object so that the rotation axis of the object and the rotation axis of the detected object match,
3. The magnetic displacement detector according to claim 1, wherein each of said plurality of detection bodies is arranged side by side facing said cylindrical circumferential surface of said detection target body. a plurality of the objects to be detected are superimposed and fixed in the direction of the rotation axis;
4. The magnetic displacement detector according to claim 3 , wherein the detection bodies are arranged side by side so as to face the cylindrical circumferential surfaces of the plurality of detection bodies. A magnetic displacement detector for detecting displacement of an object,
A plurality of objects to be detected fixed to the object, wherein the objects to be detected and the object are fixed via a first fastener, and a second fastener is provided between each of the objects to be detected. A detected object fixed via
a plurality of detection bodies that detect changes in magnetic flux density accompanying movement of the detection body and individually output signals corresponding to the positions of the detection bodies;
with
Each of the plurality of detection bodies has a magnetic flux density detection range of at least one detection body among the plurality of detection bodies. Arranged so that the region including the mounting portion of the first fastener is located ,
the first fastener and the second fastener are screws;
A magnetic displacement detector in which the object to be detected and the object are fixed by tightening the screw, and the portions between the objects to be detected are fixed . When the area including the mounting portion of the second fastener of the object to be detected is positioned within the magnetic flux density detection range of any one of the plurality of detection objects, one of the plurality of detection objects So that a region of the detected body that is not fixed to the object or a region that includes the mounting portion of the first fastener in the detected body is located in the magnetic flux density detection range of at least one detection body, 6. The magnetic displacement detector according to claim 5 , wherein the body to be detected is provided with mounting portions for the first fastener and the second fastener. The object to be detected has a cylindrical shape,
The first fastener and the second fastener are attached to the cylindrical shaft end surfaces of the respective detection objects so that the rotation axis of the object and the rotation axis of the detection object are aligned,
7. The magnetic displacement detector according to claim 5 , wherein each of said plurality of detection bodies is arranged side by side facing said cylindrical circumferential surface of said detection target body. 7. The object according to any one of claims 1 , 2, 5, or 6 , wherein each of said plurality of detection bodies is arranged side by side in a linear movement direction of said detection object fixed to said object that moves linearly. Magnetic displacement detector. The magnetic displacement detector according to any one of claims 1 to 8 , further comprising a signal processing unit that acquires displacement information of the object based on the signal output by the detection body.

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