JP2005031011A - Position detecting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the number of parts, the size, and the cost of the device for detecting the multiple rotational absolute positions of rotation axis which is an object of position detection. <P>SOLUTION: The position detecting device is constituted for detecting the absolute position within one rotation, gears are provided on the object position detection axes, not only for detection, but also for a role of driving transmitting rotation to a speed reducing mechanism. The position detecting device calculates the multiple rotational absolute position, based on the absolute position within one rotation, and the number of rotations calculated by a multiple rotation detection unit having the speed reducing mechanism. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a position detection device used for industrial machines, machine tools, and the like, and more particularly to a structure of a position detection device capable of detecting an absolute position.

  In recent years, in the industrial machine and machine tool industries, absolute position detectors are used as detectors for motors such as feed shafts.

  For absolute position detection, it is sufficient if the absolute position within one rotation is known, such as the main spindle of a machine tool, and multiple rotations are required in addition to the absolute position within one rotation, such as a feed shaft. That is, it is divided into those that require multi-rotation absolute position detection.

  As shown in FIG. 4, there is a method for detecting an absolute position within one rotation. A rotating shaft 101 that is a position detection target is supported by a plurality of bearings (not shown) and is rotatable. A detection gear for detecting the rotational position of the rotation shaft 101 is fixed coaxially with the center of the rotation shaft. The detection gear is composed of two gears 102 and 403 having different numbers of teeth. The stators 104 and 105 for detecting the gear teeth are arranged so as to surround each of the two gears 102 and 403. The stator has pole teeth arranged to face the gear teeth, and a coil is wound around the pole teeth. When the tooth tip of the gear made of a magnetic material approaches the coil, the coil excited by an excitation circuit (not shown) generates a voltage change corresponding to the change in reluctance. From the output of this voltage, the rotation of the rotating shaft that is the position detection target is detected.

  Two detection gears 102 and 403 and two sets of stators 104 and 105 are arranged by combining detection information based on the difference in the number of teeth of the detection gears 102 and 403 and processing circuit boards (not shown). This is for calculating the absolute position within one rotation at (1). The combination means that if the number of teeth of the two detection gears is different by one within one rotation of the mechanical angle of the rotating shaft to be detected, the combination of electrical angle data having a period corresponding to the number of teeth is Since there is only one way for the value of the mechanical angle, this means that the absolute position within one rotation of the mechanical angle of the rotating shaft can be uniquely determined.

  According to the structure of this position detection device, when the power is turned on again, the rotation angle within one rotation of the rotation shaft that is the position detection target at that time, that is, the absolute position within one rotation can be read.

  However, in a feed shaft for moving a table of a machine tool or the like, it is necessary to detect the number of rotations of the feed shaft because only the absolute position within one rotation is detected and the position over the multiple rotations is not known. This is called multi-rotation absolute position detection.

  In such multi-rotation absolute position detection, the number of rotations is counted, and even when the main power is turned off, it is necessary to always turn on the power for counting the number of rotations, and the type that does not need it There is. In recent years, a type that does not require a power source for counting the number of rotations is attracting attention in consideration of running costs required for periodic replacement of batteries and high costs and reduced reliability due to the need for battery supply lines. It has become like this.

  As a type that does not require a power source, there is a type in which a multi-rotation detection unit capable of detecting the number of rotations is provided on the shaft of a speed reduction mechanism connected to a rotation shaft that is a position detection target. The number of rotations may be calculated by incorporating a shaft that rotates once when the rotation shaft to be detected rotates a plurality of times in the multi-rotation detection unit, and detecting the rotation angle of the shaft with the above-described stator.

  FIG. 5 is a perspective view showing an example of a conventional structure of a detector capable of detecting a multi-rotation absolute position.

  The rotation shaft 101 that is the target of position detection can detect the absolute position within one rotation with the same structure as in FIG. 4, and the multi-rotation detection unit 113 is driven above the rotation shaft 101. A driving gear 507 is press-fitted to mesh with the driven gear 108. The rotary shaft 509 into which the driven gear 108 is press-fitted is supported and rotated by a plurality of bearings (not shown), and the bearings are housed in a housing (not shown).

  A pinion 110 is press-fitted and fixed to one end of the rotation shaft 509 of the driven gear 108. The pinion 110 is coupled to the first stage gear 111 of the multi-rotation detection unit 113 including a plurality of speed reduction mechanisms and a plurality of detection mechanisms. A detection signal from the multi-rotation detection unit 113 is sent to a processing circuit board (not shown).

  The one-turn absolute position information obtained from the stators 104 and 105 in which coils are wound around the pole teeth and the number of rotations obtained from the multi-turn detection unit 113 are sent to the processing circuit board, and the multi-turn absolute position information is calculated. Is done. The calculation of the number of rotations is as described above.

  However, in the case of this multi-rotation absolute position detection device, there are problems such as an increase in the size of the position detection device and an increase in the number of parts by connecting to a speed reduction mechanism. For example, if the rotating shaft whose position is to be detected has a relatively large diameter, use a driven gear with the same or larger diameter for deceleration from the large-diameter driving gear attached to the rotating shaft. In addition, the size of the position detection device that includes those rotating shafts and various gears has increased.

  A conventional multi-rotation absolute position detection device is a device that counts the number of rotations of the main shaft before connecting a speed reduction mechanism from a rotation shaft to be position-detected. As shown in FIG. 5, the drive gear 507 and the driven gear 108 that transmit the rotation of the rotary shaft 101 to the multi-rotation detection unit 113 are necessary, the number of parts increases, the size of the position detection device increases, and accordingly Cost.

  The present invention has been made in view of the above-described circumstances, and an object of the present invention is to provide a position detection device capable of detecting a multi-rotation absolute position that achieves reduction in the number of parts, size reduction, and cost reduction. It is to provide.

  A position detection device according to the present invention is arranged at a position where a first gear made of a magnetic material that rotates integrally with a first rotation shaft that is a position detection target and a tooth unevenness of the first gear can be detected. The absolute position detecting unit for detecting the absolute position within one rotation based on the output of the magnetic sensor that magnetically detects the tooth tip position of the first gear, and the second gear meshing with the first gear. A rotation number counting unit that is driven by a first gear and counts the number of rotations of the first rotation shaft, and from the outputs of the absolute position detection unit and the rotation number counting unit, multiple rotations of the first rotation shaft The absolute position is detected.

  In addition, another position detection device according to the present invention is made of a magnetic material, a first gear that rotates integrally with a first rotation shaft that is a target of position detection, and a position that can detect unevenness of teeth of the first gear. And an in-pitch absolute position detector that calculates an absolute position in one pitch of the teeth of the first gear based on the output of a magnetic sensor that magnetically detects the tooth tip position of the first gear. A multi-rotation absolute position detector that is driven by the first gear via a second gear that meshes with the first gear and that calculates the absolute position and the number of rotations in one rotation of the first rotation shaft. Is.

  According to another aspect of the present invention, there is provided a magnetic sensor that is arranged at a position where a rack made of a magnetic material and the unevenness of the teeth of the rack can be detected and magnetically detects the tooth tip position of the rack. Based on the output, the absolute position within one pitch of the rack teeth is calculated by an absolute position detecting unit that calculates the absolute position within one pitch and the gear meshing with the rack, and the absolute position on the rack is calculated. A rack absolute position detecting unit.

  Further, the second gear meshing with the first gear or the gear meshing with the rack can be made of a resin material.

  According to the position detection device of the present invention, since the gear used for detecting the position of the rotating shaft also serves as a drive gear, a dedicated drive gear that has been conventionally required is not required. This has the effect of reducing the number of parts and reducing costs. In addition, since the dedicated drive gear is not required, the axial length of the rotating shaft can be particularly shortened, and the effect of downsizing can be achieved.

  Hereinafter, embodiments of the present invention will be specifically described.

  FIG. 1 is a perspective view showing an example of a position detection device according to an embodiment of the present invention. In addition, the same code | symbol is attached | subjected to the same component as FIG.4 and FIG.5.

  A rotating shaft 101 that is a position detection target is supported by a plurality of bearings (not shown) and is rotatable. A detection gear for detecting the rotational position of the rotation shaft 101 is fixed coaxially with the center of the rotation shaft. The detection gear is composed of two gears 102 and 103 having different numbers of teeth. The stators 104 and 105 for detecting the gear teeth are arranged so as to surround each of the two gears 102 and 103. The stator has pole teeth arranged to face the gear teeth, and a coil is wound around the pole teeth. When a tooth tip made of a magnetic material approaches the coil, the coil is excited to generate a voltage. From the output of this voltage, the rotation of the rotating shaft that is the position detection target is detected.

  The two detection gears 102 and 103 and the stators 104 and 105 are arranged by combining the detection information based on the difference in the number of teeth of the detection gears 102 and 103 into a processing circuit board (not shown). This is for calculating the absolute position within one rotation at (1).

  The combination means that if the number of teeth of the two detection gears is different by one within one rotation of the mechanical angle of the rotating shaft to be detected, the combination of electrical angle data having a period corresponding to the number of teeth is Since there is only one way for the value of the mechanical angle, this means that the absolute position within one rotation of the mechanical angle of the rotating shaft can be uniquely determined.

  Here, as shown in FIG. 1, the detection gear 103 is thicker than the detection gear 403 of FIGS. 4 and 5, and the magnetic force generated by the stator is below the tooth surface of the gear. Detection is performed, and the upper part of the tooth surface is used as a driving gear. That is, in addition to the role of magnetic detection by the stator, this gear also serves to transmit the rotation of the rotating shaft 101 to the multi-rotation detection unit 113 via the driven gear 108.

  The rotating shaft 109 into which the driven gear 108 is press-fitted is supported and rotated by a plurality of bearings (not shown), and the bearings are housed in a housing (not shown).

  Thus, in this example, the detection gear 103 also serves as a drive gear that transmits the rotation to the multi-rotation detection unit 113, so that the number of parts is reduced and the position detection device can be downsized. ing.

  Next, FIG. 2 is a perspective view showing an example different from FIG. 1 showing the position detection apparatus of the embodiment of the present invention, and the same components as those in FIG.

  The rotating shaft 101 is supported by a plurality of bearings (not shown) and is rotatable. The position detection unit 214 including a magnetoresistive element or the like cannot detect the absolute position within one rotation of the detection gear 202 that also serves as a drive gear, but can accurately detect information for each pitch of the gear. The detection gear 202 meshes with the driven gear 108 that transmits the rotation to the multi-rotation detection unit 213.

  In this example, the multi-rotation detection unit 213 can calculate an absolute position within one rotation of the rotation shaft 101 and the number of rotations over multiple rotations, that is, a multi-rotation absolute position detection unit. The absolute position within one rotation is provided in the multi-rotation detection unit 113 by, for example, a shaft that makes one rotation in the same manner when the rotation shaft that is the position detection target makes one rotation. What is necessary is just to detect a position.

  Therefore, the number of gears on the rotating shaft 101 side can be reduced, and further space saving can be achieved. In addition, if a position detection unit is provided at a position facing the tooth surface of the detection gear 202 that also serves as a drive gear, the absolute position within one gear pitch can be detected. Based on the detection result, for example, backlash There is an advantage that can be corrected.

  FIG. 3 is a perspective view showing a case where the drive gear in FIGS. 1 and 2 is a rack.

  A rack 316 having gear-like irregularities on the surface is fixed to a non-movable part (for example, a bed) of the machine. A rack position detection unit 315 that magnetically detects the uneven portion of the rack 316 is fixed to a movable part (for example, a table) of the machine via the rack 316 and an appropriate air gap, and the rack 316 advances with respect to a predetermined movement. Move in the direction. The multi-rotation detection unit 319 includes the above-described multi-rotation absolute position detector, and is fixed to the movable part of the machine in the same manner as the rack position detection unit 315. It is the pinion gear 318 that meshes with the rack 316 in the same module and the rotating shaft 317 that is mechanically connected to the multi-rotation detection unit 319 to transmit the information on the movement (movement) of the machine.

  The rack position detection unit 315 can detect an absolute position within one rack pitch, and has an advantage that, for example, backlash can be corrected based on the detection result.

  The driven gear 108 in FIGS. 1 to 3 is made of a resin whose hardness is lower than that of a drive gear using a magnetic material, and the driven gear 108 is less likely to wear the detection portion of the detection gear 202. is there. By using resin, it is possible to reduce the weight of the position detection device, reduce noise, and reduce costs. Specifically, POM (polyacetal) resin, PPS (polyphenylene sulfide) resin, nylon, polyamide and the like are used.

  In the above description, a specific embodiment has been described, but the present invention is not limited to this. That is, as for the magnetic sensor, any magnetic sensor such as one in which a coil is wound around an iron core, one using a magnetoresistive element, or one using a Hall element can be used as the position detection device of the present invention. In addition, if the detection gear or rack or the like plays a role of a drive gear or the like for transmitting movement information to another detection device represented by a multi-rotation detection unit, the position detection of the present invention is naturally performed. It can be a device.

It is a perspective view which shows an example of the position detection apparatus of this embodiment. It is a perspective view which shows another example of the position detection apparatus of this embodiment. It is a perspective view which shows an example of the position detection apparatus different from the example of FIG.1 and FIG.2 of this embodiment. It is a perspective view which shows an example of the structure of the conventional hollow type detector. It is a perspective view which shows an example of the hollow type detector in which the conventional multi-rotation absolute position detection is possible.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Rotating shaft 102 Detection gear 103 Detection gear 104 Stator 105 Stator 106 Spacer 108 Driven gear 109 Rotating shaft 110 Pinion 111 Gear 112 Input shaft 113 Multi-rotation detection unit 202 Detection gear 213 Multi-rotation detection unit 214 Position detection Unit 315 Rack position detection unit 316 Rack 317 Rotating shaft 318 Gear 319 Multi-rotation detecting unit 403 Detection gear 507 Drive gear 509 Rotating shaft

Claims (4)

A first gear that is made of a magnetic material and rotates integrally with a first rotation shaft to be position-detected;
Absolute position detection that detects the absolute position within one rotation based on the output of the magnetic sensor that is arranged at a position where the unevenness of the teeth of the first gear can be detected and magnetically detects the tooth tip position of the first gear. And
A rotation number counting unit that is driven by the first gear through a second gear meshing with the first gear and counts the number of rotations of the first rotation shaft;
With
A position detection device for detecting a multi-rotation absolute position of the first rotation shaft from outputs of the absolute position detection unit and the rotation number counting unit. A first gear that is made of a magnetic material and rotates integrally with a first rotation shaft to be position-detected;
An absolute position within one pitch of the teeth of the first gear based on the output of a magnetic sensor that is disposed at a position where the unevenness of the teeth of the first gear can be detected and magnetically detects the tooth tip position of the first gear. An absolute position detector within one pitch for calculating the position;
A multi-rotation absolute position detector that is driven by the first gear via a second gear meshing with the first gear and calculates the absolute position and the number of rotations in one rotation of the first rotation shaft;
A position detection device comprising: A rack made of magnetic material for position detection;
One pitch for calculating the absolute position within one pitch of the rack teeth based on the output of a magnetic sensor that is disposed at a position where the unevenness of the teeth of the rack can be detected and magnetically detects the tooth tip position of the rack. Inner absolute position detector,
A rack absolute position detector that is driven by the rack via a gear meshing with the rack and calculates an absolute position of a movable part that moves with the gear on the rack;
A position detection device comprising: The position detection device according to any one of claims 1 to 3,
A position detecting device, wherein the second gear meshing with the first gear or the gear meshing with the rack is made of a resin material.