JP2008215944A - Rotation detecting apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rotation detecting apparatus capable of precisely detecting rotation of a rotational axis which does not slide axially as a matter of course, and even a rotation axis which slides axially, without malfunction. <P>SOLUTION: The rotation detecting apparatus comprises: a cylindrical body 2 made of a magnetic material which is coupled with a rotating body 1a which slides axially, so as to be rotated thereby, and has a plurality of magnetic poles 5 being disposed along its circumferential surface; and magnetic detection means 3, 4 facing the cylindrical body 2 through a prescribed spacing, wherein the magnetic field area formed by the magnetic detection means 3, 4 and the magnetic poles 5 is equivalent to or exceeds the amount of slide of the rotating body 1a in the direction of the rotational axis. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a rotation detection device that detects rotation of a rotation shaft, and more particularly to a rotation detection device used for rotation detection of a rotation shaft that has a large amount of sliding in the axial direction.

  There are optical, magnetic, inductive, and mechanical types of rotation detectors based on the detection principle, and there are pulse transmission types and resolver types based on the signal classification. in use. As these rotation detection devices, various types of rotation detection devices that detect a rotation shaft with a large radial shaft runout, or rotation detection devices that are insensitive to axial sliding of the rotation shaft, have been proposed. be able to.

  That is, as a rotational position detector of the rotating shaft, a circular magnet is magnetized on the outer periphery, and a Hall element is placed at a position where the magnetic flux of the rotor rotating around the shaft extends. Has been proposed (see, for example, Patent Document 1).

  In addition, a soft magnetic body having magnetic anisotropy formed on the flat surface at the end of the rotating shaft and a coil fixed to face the soft magnetic body and having magnetic anisotropy There has been proposed a rotation speed sensor that detects a change in magnetic permeability accompanying rotation with a coil (see, for example, Patent Document 2).

  Further, a rotation angle detection device using a ferromagnetic magnetic sensor has been proposed that is small in size, can improve resolution, and can detect the absolute rotation angle (for example, Patent Documents). 3).

  In addition, as a rotation detection device that detects rotation information of a rotating shaft with a large radial shaft shake in a non-contact manner, a rotation detector and a shaft shake detector that detects the shaft shake of a rotating body are provided. There has been proposed a rotation detection device provided with signal processing means for processing a rotation detection signal and an axial vibration detection signal from an axial vibration detector and removing an axial vibration component from the signal component of the rotation detection signal (for example, a patent Reference 4).

  Furthermore, a rotation angle sensor that allows a shaft deflection in the radial direction of the rotating shaft and can be used for a machine that rotates at an ultra high speed, a special machine, or an industrial rotating machine has been proposed (for example, see Patent Document 5).

Japanese Patent Laid-Open No. 58-162813 (claimed column, FIG. 4) JP-A-5-333032 (Summary column, FIG. 1) JP-A-61-292503 (page 2, upper right column, lines 12 to 15, line 1) JP 2001-201362 A (summary column, FIG. 1) JP-A-4-366716 (paragraph 0001, FIG. 1)

  As described above, many proposals have been made for a rotation detection device that detects the rotation of the rotary shaft. However, a rotary shaft having a large amount of sliding in the rotary shaft direction, such as a large motor or a rotary machine, has been proposed. There is no proposal or disclosure of a rotation detection device applicable to rotation detection.

  By the way, a rolling bearing is adopted for a general industrial rotating electric machine, for example, a bearing of an electric motor. However, a sliding bearing is adopted for a bearing in a large rotating machine such as a large electric motor. This is because the application of rolling bearings is limited by the peripheral speed conditions, load conditions, vibration conditions, etc. of the sliding surface. In particular, a large size rotating machine with a large capacity will inevitably adopt a sliding bearing. . However, a problem in detecting the rotation of the rotary shaft in a large-sized rotating machine in which the slide bearing is employed is the amount of sliding in the axial direction of the rotary shaft generated from the structure of the slide bearing.

  In other words, rolling bearings (especially ball bearings) have a structure that suppresses sliding in the axial direction, and the sliding of the rotating shaft is about the degree of thermal expansion accompanying the rise in temperature, whereas large rotating machines have a sliding bearing. Since it is adopted, a sliding amount in the axial direction is generated on the rotating shaft. The amount of sliding is called an end play, and the total amount of sliding at both ends is called an end float. This end play is 5 mm for a large rotating machine, and the end float is twice as large as 10 mm.

  Normally, in the case of a rotating machine such as an electric motor, the rotating shaft is attracted to the center of the end float (the center position of the magnet) by the electromagnetic force generated by the startup. However, the thrust force from the mechanical shaft of the driven mechanical device is reduced. In response, the rotating shaft slides. Generally, the end play value of the machine shaft is set smaller than the end play value of the rotating shaft and is limited from the machine side, so the actual distance that the rotating shaft slides is less than half of the end float of the rotating shaft. In many cases, however, sliding of about several mm occurs on the rotating shaft.

  Even in this large rotating machine, a rotation detecting device is used to detect the actual rotation and achieve the purpose for the purpose of monitoring or protection or variable speed control. There is no current state of obtaining a rotation detecting device that can satisfy the detection accuracy by sliding in the direction.

  The present invention has been made in view of the above-described situation in the prior art. In addition to a rotating shaft that does not slide in the axial direction, rotation of the rotating shaft does not malfunction even with respect to a rotating shaft that slides in the axial direction. An object of the present invention is to provide a rotation detection device that can detect with high accuracy.

  A rotation detection device according to the present invention is a rotation detection device that detects the rotation of a rotating body that slides in the direction of the rotation axis in a non-contact manner, and is connected to the rotating body to rotate, and a plurality of magnetic poles are circumferential surfaces. A magnetic body formed along the cylindrical body, and a magnetic detection means facing the cylindrical body with a predetermined gap therebetween, and a magnetic field region formed by the magnetic detection means and the magnetic pole is rotated. The magnetic field region is greater than the amount of sliding of the body in the rotation axis direction.

  According to the rotation detection device of the present invention, the rotational position of the rotary shaft can be detected with high accuracy without malfunction, not only for the rotary shaft that does not slide in the axial direction but also for the rotary shaft that slides in the axial direction. There is.

  Exemplary embodiments of a rotational axis detection device according to the present invention will be described below with reference to the accompanying drawings. For convenience of explanation, an electric motor is taken as an example of a rotating machine, and a rotation detecting device that detects the rotation of the rotating shaft will be described. However, the present invention is not limited to this, and other rotating machines such as a generator. The present invention can be applied to the rotation detection of the rotation shaft.

Embodiment 1 FIG.
FIG. 1 is a configuration diagram of a rotation detection device according to the first embodiment. In FIG. 1, a cylindrical body, for example, a cylindrical disk 2 is mechanically attached and connected to a rotating shaft 1a of an electric motor 1 so as to be concentric. An MR detector (a magnetoresistive effect detector, hereinafter simply referred to as a detector) 3 is fixedly installed through a certain gap from the outer peripheral surface of the cylindrical disk 2, and this detector A detector 4 is fixedly installed oppositely through 3 and a cylindrical disk 2. The electric motor 1 is a large-capacity large electric motor, and the rotating shaft 1a generates an end float of about several millimeters as described above.

  On the other hand, an even number of strip-shaped magnetic poles 5 are formed in parallel and uniformly on the outer peripheral surface of the cylindrical disk 2 in the axial direction of the rotating shaft 1 a of the electric motor 1. The magnetic pole 5 is configured, for example, by applying a magnetic material to the outer peripheral surface of the cylindrical disk 2 to form a magnetic material layer and magnetizing the magnetic material layer. The magnetic pole 5 and the detector 3 constitute a first non-contact detecting means 6, and the magnetic pole 5 and the detector 4 constitute a second non-contact detecting means 7. The output voltage that is the detection signal of the detector 3 and the detector 4 is output to the correction circuit 8 of the combined signal generation unit, and is output from the correction circuit 8 to the signal processing circuit 9 of the signal processing unit. ing. Further, the axial length, that is, the thickness of the cylindrical disk 2 is configured to be not less than the sliding amount Lmm of the rotating shaft 1a of the electric motor 1, and the magnetic pole 5 is similarly not less than the sliding amount Lmm of the rotating shaft 1a of the electric motor 1. It is configured and arranged. The operations and actions of the correction circuit 8 and the signal processing circuit 9 will be described later.

  FIG. 2 is a configuration diagram of the rotation detection device in which the rotation detection device shown in FIG. 1 is provided with a detection signal monitoring circuit which is a monitoring means for monitoring the detection result. In this figure, the monitoring means for monitoring the detection result of the rotation detecting device, that is, the detection signal monitoring circuit 20 is composed of an arithmetic processing circuit 22 including a logic circuit 21 and a display means 23. The output voltage of the detector 3 is input to the waveform amplitude average value calculator 24 and the maximum and minimum amplitude calculator 25, and the output voltage of the detector 4 is input to the waveform amplitude average value calculator 26 and the maximum and minimum amplitude calculator 27. Each amplitude is calculated. The calculation results of the waveform amplitude average value calculators 24 and 26 and the maximum and minimum amplitude calculators 25 and 27 are output to the logic circuit 21 and also to the display means 23.

The rotation detection device according to the first embodiment is configured as described above, and the operation and action thereof will be described next.
When the rotating shaft 1a of the electric motor 1 rotates, the cylindrical disk 2 that is mechanically attached and connected rotates, and the magnetic pole 5 formed on the outer periphery rotates. By this rotation, the detectors 3 and 4 sense a change in magnetic flux and output a voltage associated with the change in magnetic flux. And even if the rotating shaft 1a slides in the axial direction, the detectors 3 and 4 can obtain a continuous output voltage without departing from the magnetic field region. In addition, the conventional rotation detection device used for detecting the rotation of the motor shaft or the like is for the rotation shaft 1a not to slide in the axial direction or to absorb the sliding with the extent of expansion or contraction due to heat even if sliding. The object to be detected is a combination of the rotating shaft 1a and the shaft of the rotation detector by a flexible coupling, both of which are based on the assumption that the positions of the cylindrical disk 2 and the rotation detector do not shift, It has been difficult to apply to applications where the rotating shaft 1a slides.

  When the rotating shaft 1a of the electric motor 1 rotates to rotate the cylindrical disk 2, the output voltage shown in FIG. FIG. 3 is a graph showing time on the horizontal axis and the output voltage of the detector 3 or the detector 4 on the vertical axis, and FIG. 3a shows a case where the rotating cylindrical disk 2 is not attached to the shaft (an ideal case). FIG. 3b shows the case where the mounting of the rotating cylindrical disk 2 causes an axial runout (the figure is the same even with a declination).

  In FIG. 3a, the detection signal waveforms of the detectors 3 and 4 have the same shape and the same phase. FIG. 3b shows the maximum shaft deflection time point, and the output voltage of the detector 3 becomes the maximum value at the position where the distance between the detector 3 and the magnetic pole 5 is closest, but it is farthest from the magnetic pole 5 on the detector 4 side. The output voltage becomes the minimum value. These output voltages are input to the correction circuit 8, and the voltage is added by the correction circuit 8 to become a combined voltage of the detectors 3 and 4, but is corrected to a voltage that does not include the shaft shake shown in FIG. Is done. FIG. 4 shows the output voltage (combined voltage) of the correction circuit 8, where the horizontal axis represents time and the vertical axis represents the combined voltage of the output voltages of the detectors 3 and 4.

  FIG. 5 shows an output voltage waveform of the signal processing circuit 9. The signal processing circuit 9 thresholds the composite voltage output from the correction circuit 8 at a predetermined level to obtain a short-wave output voltage. This output voltage has a pulse waveform. If the sliding amount of the rotating shaft 1a of the electric motor 1 is within Lmm, the amount of magnetic flux received from the magnetic pole 5 does not change, that is, if the sliding amount is within Lmm, the magnetic flux received by the detectors 3 and 4 at any sliding position. The amount does not change and the output voltage is uniform.

  FIG. 6 is a diagram showing an operation flow of the logic circuit 21, and the logic circuit 21 operates as follows. That is, when the average amplitude value from the waveform amplitude average value calculators 24 and 26 and the maximum and minimum amplitude values from the maximum and minimum amplitude calculators 25 and 27 are input (ST1), first, the waveform amplitude average value calculator 24 is set. Are compared with the average amplitude value of the waveform amplitude average value calculator 26 (ST2). As a result, if the average amplitude value of the waveform amplitude average value calculator 24 is large, the detector 3 and the cylindrical disk 2 are too close, the mounting position of the detector 3 is corrected (ST3), and the waveform amplitude average If the average amplitude value of the value calculator 24 is small (ST4), the detector 4 and the cylindrical disk 2 are too close, and the mounting position of the detector 4 is corrected (ST5).

  Thereafter, it is confirmed whether the maximum amplitude value and the minimum amplitude value of the maximum and minimum amplitude calculator 25 or 27 are greatly separated (ST6), and if they are largely separated, the cylindrical disk 2 is axially shaken or eccentric. The mounting position of the cylindrical disk 2 is corrected (ST7).

  The calculation results of the waveform amplitude average value calculators 24 and 26 and the maximum and minimum amplitude calculators 25 and 27 are displayed on the respective display units 23a to 23d of the display means 23 as shown in the display example in FIG. .

  As described above, according to the rotation detection device according to the first embodiment, the rotation shaft 1a rotates with respect to the rotation shaft 1a that slides in the axial direction while corresponding to the radial shaft runout of the rotation shaft 1a. Can be accurately detected without malfunction, and the detection state can be monitored.

Embodiment 2. FIG.
Next, a second embodiment will be described. In the first embodiment, it is assumed that an even number of strip-like magnetic poles 5 are formed in parallel and uniformly on the outer peripheral surface of the cylindrical disk 2 in the axial direction of the rotating shaft 1a of the electric motor 1. However, in actual manufacture, it may be difficult to form the magnetic pole 5 in a uniform shape. This will be described with reference to FIG. 8. FIG. 8 a is an enlarged schematic view of the relationship between one magnetic pole 80 and the detector 3 when the rotary shaft 1 a slides, and the shape (boundary) of the magnetic pole is not accurately formed. The case where the nonuniform part 81 has arisen is shown. The broken line indicates the position of the magnetic pole 80 when the rotating shaft 1a moves in the axial direction.

  FIG. 8b shows the output voltage of the detector 3 in FIG. 8a, which is simulated for the sake of convenience. Although the output voltage of the detector 3 is generated by the magnetic flux, the axial movement of the rotating shaft 1a starts and the rotating part (magnetic pole) 80 moves, and the detector 3 catches the passage of the magnetic flux non-uniform part 81. The output voltage changes. The detector 3 passes through the non-uniform part 81 of the magnetic flux and is located at a magnetic pole part where the magnetic flux is uniform after t seconds. The output voltage of the detector 3 is distorted before and after passing through the non-uniform part 81 of the magnetic flux as compared with the case where the magnetic flux is uniform, and is in a kind of “blurred” state. Become.

  In this way, especially when the rotating shaft 1a moves in the axial direction during the stop and an erroneous pulse is generated, the start-up condition is not satisfied and the start-up is impossible in a system provided with an interlock such as a complete stop. The second embodiment obtains a rotation detection device that prevents the generation of erroneous pulses during sliding due to non-uniformity of magnetic poles by devising the shape of the magnetic poles.

  That is, FIG. 9 is a block diagram showing the rotation detecting device according to the second embodiment, in which the shape of the belt-like magnetic pole 91 is formed by providing a slight angle in the axial direction (a few degrees or less with respect to the horizontal axis). That is, the strip-shaped magnetic pole 91 is formed in a skewed pattern. Since other configurations are the same as those in the first embodiment, the same reference numerals are used and description thereof is omitted.

  Next, the improvement effect by Embodiment 2 is demonstrated using FIG. That is, FIG. 10A is a schematic diagram showing an enlarged relationship between one magnetic pole 91 and the detector 3 when the rotary shaft 1a slides in the axial direction, and the shape (boundary) of the magnetic pole is not accurately formed. The case where the nonuniform part 81 has arisen is shown. In addition, the broken line has shown the position of the magnetic pole 91 at the time of the axial movement of the rotating shaft 1a.

  FIG. 10b shows the output voltage of the detectors 3 and 4 and the output voltage of the correction circuit 8 in FIG. 10a, and for the sake of convenience, is simulated in a state where rotation is stopped. Although the outputs of the detectors 3 and 4 are generated by the magnetic flux, the axial movement of the rotating shaft 1a starts and the rotating part (magnetic pole) 91 moves. In FIG. 10b, when the rotary shaft 1a is moved in the axial direction, the detector 3 moves closer to the magnetic pole 91, that is, in a region where the magnetic flux increases, based on the relationship between the skew direction of the magnetic pole 91 and the moving direction of the rotary shaft 1a. The detector 4 mounted oppositely moves in a direction away from the magnetic pole 91, that is, in a region where the magnetic flux decreases. The detector 3 captures the passage of the magnetic flux non-uniform part 81 and the output voltage changes. Although the output voltages of the detectors 3 and 4 are synthesized by the correction circuit 8, a short waveform “blade” state does not occur in the synthesized waveform (voltage), and the rise (fall) time of the waveform is delayed. appear.

  As described above, according to the second embodiment, the generation of erroneous pulses due to the axial movement of the rotating shaft 1a is prevented, and it is particularly effective for the axial movement of the rotating shaft 1a that is stopped. Note that if the skew angle is set large, the rotation angle of the detection signal will be shifted before and after sliding of the rotary shaft 1a. In the case of rotation angle control, the skew angle is set within a range that does not hinder the control. There is a need to.

Embodiment 3 FIG.
Next, a third embodiment will be described. In the first embodiment, it is assumed that an even number of strip-like magnetic poles 5 are formed in parallel and uniformly on the outer peripheral surface of the cylindrical disk 2 in the axial direction of the rotating shaft 1a of the electric motor 1. However, it may be difficult to form a uniform and elongated magnetic pole. In the third embodiment, the magnetic pole has a shape (structure) that easily forms a uniform magnetic flux such as a circle, and conversely, the detectors facing each other are attached as elongated shapes in the axial direction. When it is difficult to manufacture a long and narrow detector, it can be realized by applying a plurality of detectors in the axial direction.

  As described above, in the third embodiment, the magnetic pole has a circular shape or the like and the detection width is widened on the detector side to prevent the magnetic pole from being unevenly formed (magnetic flux nonuniformity) and to slide. A rotation detection device that prevents generation of erroneous pulses during movement is obtained.

  That is, FIG. 11 is a block diagram showing the rotation detecting device according to the third embodiment. Instead of the strip-shaped magnetic poles 5 and 91 of the first or second embodiment, a circular magnetic pole 110 is used instead of the first or second embodiment. An even number is arranged on the circumferential surface of the cylindrical disc 111 having a thickness smaller than that of the cylindrical disc 2 of the second embodiment, and detectors 112 and 113 are attached instead of the detectors 3 and 4. The detector 112 has a structure capable of detecting in the axial direction longer than the sliding distance L of the rotating shaft 1a, and the detector 113 facing the detector 112 via the cylindrical disk 111 is the same. Since other configurations are the same as those in the first embodiment or the second embodiment, the same reference numerals are given and description thereof is omitted.

  Since Embodiment 3 has the above-described configuration, even when it is difficult to form a uniform and elongated magnetic pole, the magnetic pole has a shape such as a circular shape that facilitates the formation of a uniform magnetic pole, and the magnetic pole moves along with the movement of the rotating shaft 1a. Even if the rotating disk 111 moves, detection by the detectors 112 and 113 is possible over the entire sliding region without departing from the detection region of the fixedly mounted detectors 112 and 113, and the rotating shaft 1a on which the motor 1 slides. The rotation detection device suitable for the rotation detection can be obtained.

  In each of the above-described embodiments, the case has been described in which the MR detector that is opposed to the outer peripheral surface of the cylindrical body through a certain gap is used as the non-contact detection means. However, the present invention is not limited to this. Rather, it encompasses various design changes.

  The rotation detecting device according to the present invention can be used for detecting rotation of a rotating shaft of a large-sized electric motor or rotating machine, particularly a rotating machine having a large amount of sliding in the axial direction.

It is a block diagram of the rotation detection apparatus which concerns on Embodiment 1 of this invention. It is a block diagram of the rotation detection apparatus which provided the detection signal monitoring circuit which monitors the detection result in the rotation detection apparatus which concerns on Embodiment 1 of this invention. It is a figure which shows the detection signal of the rotation detection apparatus which concerns on Embodiment 1 of this invention, shows a time on a horizontal axis, and a detection signal on a vertical axis. It is a figure which shows the output voltage (synthetic signal) of the correction circuit of the rotation detection apparatus according to Embodiment 1 of the present invention, wherein the horizontal axis represents time and the vertical axis represents the output voltage (synthetic voltage). It is a figure which shows the output signal waveform of the signal processing circuit of the rotation detection apparatus which concerns on Embodiment 1 of this invention. It is a figure which shows the operation | movement flow of the logic circuit of the rotation detection apparatus which concerns on Embodiment 1 of this invention. It is a figure which shows the example of a display displayed on the indicator of the rotation detection apparatus which concerns on Embodiment 1 of this invention. It is a schematic diagram explaining the operation | movement background of the rotation detection apparatus which concerns on Embodiment 2 of this invention. It is a block diagram of the rotation detection apparatus which concerns on Embodiment 2 of this invention. It is a schematic diagram explaining operation | movement of the rotation detection apparatus which concerns on Embodiment 2 of this invention. It is a block diagram of the rotation detection apparatus which concerns on Embodiment 3 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electric motor 1a Rotating shaft 2,111 Cylindrical disk 3,4,112,113 MR detector 5,80,91,110 Magnetic pole 6 1st detection means 7 2nd detection means 8 Correction circuit 9 Signal processing circuit 20 Detection signal monitoring circuit 21 Logic circuit 22 Arithmetic processing circuit 23 Display means 23a to 23d Display units 24 and 26 Waveform amplitude average value calculators 25 and 27 Maximum and minimum amplitude calculators 81 Magnetic pole nonuniformity portion

Claims (7)

A rotation detection device that detects rotation of a rotating body that slides in the direction of the rotation axis in a non-contact manner, wherein the magnetic material is connected to the rotating body and rotates, and a plurality of magnetic poles are formed along a circumferential surface. A cylindrical body, and magnetic detection means facing the cylindrical body via a predetermined gap,
A rotation detection device, wherein a magnetic field region formed by the magnetic detection means and the magnetic pole is a magnetic field region equal to or greater than a sliding amount in the rotation axis direction of the rotating body.   The magnetic pole is a strip-shaped magnetic pole, and the length in the rotation axis direction of the cylindrical body is configured to be longer than the sliding amount in the rotation axis direction of the rotation body, and the length of the band-shaped magnetic pole is set in the rotation axis direction of the rotation body. The rotation detection device according to claim 1, wherein the rotation detection device is configured to have a length equal to or greater than a sliding amount.   The rotation detecting device according to claim 2, wherein the strip-shaped magnetic poles are formed in parallel to each other in the rotation axis direction of the cylindrical body.   The rotation detecting device according to claim 2, wherein the belt-like magnetic poles are formed to be inclined with respect to the rotation axis direction of the cylindrical body, and the magnetic poles are formed in parallel to each other.   2. The rotation detection device according to claim 1, wherein the length of the cylindrical body of the magnetic detection means in the rotation axis direction is longer than the sliding amount of the rotation body in the rotation axis direction.   The magnetic detection means is composed of first and second magnetic detection means facing each other through the cylindrical body, and a detection signal of the first magnetic detection means and a detection signal of the second magnetic detection means 6. A composite signal generating means for generating a composite signal of the above and a signal processing means for generating a pulse signal from an output signal of the composite signal generating means. The rotation detection device described.   The rotation according to claim 6, further comprising monitoring means for monitoring a detection result of the rotation detection device based on a detection signal of the first magnetic detection means and a detection signal of the second magnetic detection means. Detection device.

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