JP2012002716A - Rotation detection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rotation detection device for detecting positioning of a rotation axis at a predetermined rotation angle without calculating a rotation angle.SOLUTION: A shift position detection device 2 includes: a magnet 21 arranged to change the direction of a magnetic field in accordance with the rotation of a shaft 3; MR sensors which output signals according to the magnetic field of the magnet 21 and are arranged to change over the signals to be outputted when the shaft 3 is at a predetermined rotation angle; and shift position detection means 801 for detecting the angular range of the shaft 3 in accordance with the combination of the signals to be outputted from the multiple MR sensors 200a-200d by arranging the MR sensors 200a-200d so as to respectively differ the rotation angles to change over the signals to be outputted from the multiple MR sensors 200a-200d.

Description

  The present invention relates to a rotation detection device that detects a rotation angle of a rotation shaft.

  2. Description of the Related Art Conventionally, there is a rotation detection device that detects a rotation angle of a rotation shaft by detecting a change in a magnetic field using a magnetic detection element (see, for example, Patent Document 1). The rotation detection device includes two magnets that rotate around the rotation shaft as the rotation shaft rotates, and a magnetic sensor that detects a change in the magnetic field generated from the two magnets when the rotation shaft rotates and outputs a signal. And an arithmetic circuit for calculating the rotation angle of the rotary shaft from the signal output from the magnetic sensor and a control unit.

  According to this rotation detection device, two detection units each including a magnetoresistive element as a magnetic sensor configured by a bridge circuit are provided so that each detects a magnetic field differently, and a difference between output signals of the two detection units is calculated. By doing so, the change of the magnetic field emitted from the two magnets rotating around the rotation axis with the rotation of the rotation axis is detected. For this reason, the rotation angle of a rotating shaft can be detected continuously.

JP 2010-38766 A

  However, the rotation detection device disclosed in Patent Document 1 detects the rotation angle of the rotation axis after calculating the rotation angle of the rotation axis in order to determine whether the detected rotation angle of the rotation axis is within a predetermined rotation angle range. It has been necessary to determine whether the rotation angle is within a predetermined rotation angle range.

  Accordingly, an object of the present invention is to provide a rotation detection device that can detect that the rotation axis is positioned at a predetermined angle without calculating the rotation angle.

  One embodiment of the present invention outputs a signal according to a magnet disposed with respect to the rotating shaft so that the direction of the magnetic field changes with rotation of the rotating shaft, and the rotating shaft is previously A plurality of the magnetic sensors are arranged so that a rotation angle at which a signal output from the magnetic sensor is switched is different from a magnetic sensor arranged so that a signal output when the rotation angle is at a predetermined rotation angle, and the plurality of magnetic sensors There is provided a rotation detecting device having detecting means for detecting an angle range of the rotating shaft in accordance with a combination of signals output from a sensor.

  The rotation detection device may further include a speed reducer that transmits a rotation angle of the rotation shaft and a rotation angle of the magnet in a magnetic field direction at a predetermined ratio.

  The magnet of the rotation detecting device may be formed in a flat plate shape and magnetized so as to generate a magnetic field in parallel with the surface, and the magnetic sensor may be arranged in parallel with the surface of the magnet.

  According to the present invention, it is possible to detect that the rotation axis is positioned at a predetermined angle without calculating the rotation angle.

FIG. 1 is a schematic perspective view showing a shift position detection device according to a first embodiment of the present invention. 2A and 2B are schematic views showing the configuration of the shift position detection device 2 according to the first embodiment of the present invention, where FIG. 2A is a plan view and FIG. Is a front view. 3A and 3B are diagrams for explaining the arrangement relationship of the MR sensor 200a according to the first embodiment of the present invention. FIG. 3A is a schematic plan view, and FIG. b) is a chart showing an arrangement relationship with respect to the reference direction A; FIG. 4 is a block diagram for explaining a circuit configuration of the shift position detection apparatus 2 according to the first embodiment of the present invention. FIG. 5 is a diagram showing the contents of the shift position information 810 according to the first embodiment of the present invention. 6A to 6E are schematic plan views showing the arrangement of the magnet 21 and the shift lever 4 at the shift positions 70a to 70e according to the first embodiment of the present invention. 7A to 7C are a graph and a correspondence table showing output signals of the MR sensors 200a to 200d of the shift position detection device 2 according to the first embodiment of the present invention. FIG. 8 is a schematic perspective view showing a shift position detecting apparatus according to the second embodiment of the present invention.

[First Embodiment]
(Configuration of shift position detection device)
FIG. 1 is a schematic perspective view showing a shift position detection device according to a first embodiment of the present invention.

  The shift position detection device 2 is provided, for example, in a shift unit 1 of a vehicle, and changes with the rotation of the shaft 3 and a disk-shaped magnet 21 attached to one end of a metal shaft 3. And a magnetic sensor unit 20 that detects the direction of the magnetic field of the magnet 21. The magnetic sensor unit 20 outputs a signal according to the detected direction of the magnetic field, and an ECU described later determines the rotational position of the shaft 3 from the output signal.

  The magnetic sensor unit 20 has a plurality of MR (Magneto Resistance) sensors, which will be described later. The MR sensor, for example, an IC that converts a bridge circuit using a plurality of MR elements and outputs the signal by converting the output of the bridge circuit. Consists of. The bridge circuit has a predetermined magnetic sensing direction and outputs a value proportional to a sine component of an external magnetic field with respect to the magnetic sensing direction. That is, when the magnetic sensing direction and the direction of the external magnetic field coincide (or when the magnetic sensing direction and the direction of the external magnetic field are opposite to each other), the output value is the largest (or smaller). Further, when the magnetic sensing direction and the direction of the external magnetic field are orthogonal, the output value is zero. The IC outputs a high signal (for example, + 5V) when the output of the bridge circuit is positive, and outputs a low signal (for example, 0V) when the output is negative.

  The shift unit 1 is visually operated with a shift lever 4 having one end connected to the shaft 3 by a connecting member 30 and the other end as a grip portion, a shift gate 5 for guiding the shift lever 4, and a shift position of the shift lever 4. And a shift panel 6 made of a synthetic resin having a shift position display portion 7 to be presented to a person.

  The shift lever 4 is configured to move the shift positions 70a to 70e according to the indications “P”, “R”, “N”, “D”, and “L” on the shift position display unit 7 in a stepped manner. The shaft 3 has notches and the like (not shown) at positions corresponding to the shift positions 70a to 70e so that the shift lever 4 moves in a stepped manner. “P”, “R”, “N”, “D”, and “L” indicate the operating state of the drive system of the vehicle, and indicate the states of parking, rear, neutral, drive, and low gear. Moreover, the other end opposite to the one end where the magnet 21 of the shaft 3 is provided may be connected to another mechanism such as a shift lock mechanism.

  2A and 2B are schematic views showing the configuration of the shift position detection device 2 according to the first embodiment of the present invention, where FIG. 2A is a plan view and FIG. Is a front view.

  The magnetic sensor unit 20 includes a plurality of MR sensors 200a to 200d arranged on a disk-shaped circuit board 200. The magnet 21 is composed of a semicircular N pole 21a and S pole 21b, has a disk shape with a diameter of about 15 mm, and is attached to one end of the shaft 3 by bonding or the like. In addition, the magnitude | size of the magnet 21 is an example and may be changed suitably.

  The magnetic sensor unit 20 and the magnet 21 each have a center on the central axis of the shaft 3 and are arranged close enough so that the disk surfaces are parallel to each other and the magnetic field of the magnet 21 can be detected.

  The MR sensors 200a to 200d are arranged inside the board surface of the magnet 21 projected from the axial direction of the shaft 3 on the board surface of the circuit board 200 in order to detect a magnetic field parallel to the board surface of the magnet 21, and the respective magnetosensitive directions are set. Set to a different orientation. Note that the number of MR sensors is not limited to four, and may be increased or decreased based on the number of shift positions.

  3A and 3B are diagrams for explaining the arrangement relationship of the MR sensor 200a according to the first embodiment of the present invention. FIG. 3A is a schematic plan view, and FIG. b) is a chart showing an arrangement relationship with respect to the reference direction A;

As shown in FIG. 3 (a), MR sensor 200a has its magneto-sensitive direction _{B a} non-magnetism-sensitive directions NB _a perpendicular to, with respect to the reference direction A Mukan磁direction NB _a is predetermined It is disposed at an angle of alpha _a Te. Although not shown, the same applies to the MR sensor 200B～200d, are disposed at an angle of alpha _b to? _D relative to Mukan磁direction _NB b to NB _d is the reference direction A. Further, the reference direction A may be set freely by the manufacturer or the user.

As shown in FIG. 3 (b), MR sensor 200a~200d is no magneto-sensitive direction _NB a to NB _d are each 15 ° to the reference direction A, respectively, 30 °, 45 °, an angle of 60 ° Are arranged as follows. These angles can be freely set as long as the MR sensor detects the magnetic field within a period of 180 °. In addition, when the MR sensor has a period with an angle different from 180 °, the MR sensor can be set within the period.

  FIG. 4A is a block diagram for explaining a circuit configuration of the shift position detection apparatus 2 according to the first embodiment of the present invention.

  The shift position detection device 2 is connected to a plurality of MR sensors 200a to 200d, receives an output signal and outputs a calculation result by calculation or the like, a storage unit 81 such as a nonvolatile flash memory for storing information, and the like. And an output unit 82 that converts an output signal based on the calculation result of the ECU 80 into a signal suitable for an output destination and outputs the signal.

  The ECU 80 is based on the MR sensor output receiving means 800 that receives the output signals of the MR sensors 200a to 200d, the output signal received by the MR sensor output receiving means 800, and shift position information 810 described later stored in the storage unit 81. Shift position detecting means 801 for detecting whether the shift lever 4 is located in any of the shift positions 70a to 70e. The shift position detection unit 801 generates an output signal as a calculation result based on the detected shift position and outputs the output signal to the output unit 82.

  The output unit 82 receives the output signal of the shift position detecting means 801 of the ECU 80, converts it into a signal suitable for the output destination, and outputs it. The output destination is, for example, a shift position display lamp provided on the meter panel, and outputs a signal for lighting the corresponding shift position lamp.

FIG. 5 is a diagram showing the contents of the shift position information 810 according to the first embodiment of the present invention.
The shift position information 810 is information registered in advance, and defines combinations of output signals of the MR sensors 200a to 200d in association with the shift positions 70a to 70e. The shift position detection means 801 determines that the shift lever 4 is located at a shift position that matches the combination of output signals of the MR sensors 200a to 200d in the shift position information 810.

(Operation)
First, when the driver moves the shift lever 4 to any one of the shift positions 70 a to 70 e along the shift gate 5, the shaft 3 rotates as the shift lever 4 moves. The magnet 21 rotates together with the shaft 3, and the direction of the magnetic field changes following it.

  6A to 6E are schematic plan views showing the arrangement of the magnet 21 and the shift lever 4 at the shift positions 70a to 70e according to the first embodiment of the present invention.

  As shown in FIG. 6A, when the shift lever 4 is positioned at the shift position 70a, the direction of the magnetic field on the surface of the magnet 21 is within the range of 15 ° counterclockwise from the rotation angle at which the direction of the magnetic field is parallel to the reference direction A. A magnet 21 is disposed on the surface.

  The magnets 21 in FIGS. 6B to 6E are rotated by 15 ° in the counterclockwise direction with reference to the rotation angle of FIG. 6A, and the shift lever 4 is in the shift positions 70b to 70e, respectively. Located in.

  Next, the MR sensors 200a to 200d of the magnetic sensor unit 20 detect a magnetic field generated by the magnet 21 and output a Low (L) signal or a High (H) signal.

  FIGS. 7A and 7B are diagrams illustrating output signals of the MR sensors 200a to 200d of the shift position detection device 2 according to the first embodiment of the present invention, and FIG. 7 is a graph showing the relationship between the magnetic field detected by the sensors 200a to 200d and the angle of the magnet 21, and FIG. 7B is a graph showing the relationship between the signal output from the MR sensors 200a to 200d and the angle of the magnet 21. FIG.

Since the MR sensors 200a to 200d detect the sine component of the magnetic field with respect to the magnetosensitive direction B _i , as shown in FIG. 7A, each of the MR sensors 200a to 200d behaves as a sine function with a period of 180 ° based on the rotation angle of the shaft 3. The sine function becomes 0 when the magnetically insensitive direction NB _i of the MR sensors 200a to 200d and the direction of the magnetic field of the magnet 21 coincide, and becomes opposite when the magnetically sensitive direction B _i and the direction of the magnetic field of the magnet 21 coincide. When it reaches the maximum or minimum value.

Since the MR sensors 200a to 200d output an H signal when a positive magnetic field is detected, and output an L signal when a negative magnetic field is detected, as shown in FIG. 200 a to 200 d output signals so that the L signal and the H signal are switched at the rotation angles at which the insensitive direction NB _i and the direction of the magnetic field of the magnet 21 coincide with each other.

  Next, the MR sensor output receiving means 800 of the ECU 80 receives the output signals of the MR sensors 200a to 200d, and the shift position detecting means 801 determines the shift position that matches the combination of the received L signal and H signal as the shift position. Detection is based on information 810.

  For example, when the shift lever 4 is located at the shift position 70b, the direction of the magnetic field of the magnet 21 is located within a rotation angle range of 15 ° to 30 ° with respect to the reference direction A. Therefore, the MR sensor 200a outputs an H signal. The MR sensors 200b to 200d output an L signal. The shift position detecting means 801 detects the shift lever 4 at the position of the shift position 70b from these signals and the shift position information 810.

(Effects of the first embodiment)
According to the first embodiment described above, the shift position detecting means 801 has the shaft based on the combination of the L signal or H signal output depending on the relationship between the arrangement angle of the MR sensors 200a to 200b and the direction of the magnetic field of the magnet 21. 3 is detected, it is possible to detect that the rotation axis is positioned at a predetermined angle without performing an operation such as calculating the rotation angle from the magnetic resistance of the MR element or the like.

  Further, since none of the MR sensors 200a to 200b and the shift position detecting means 801 need to detect the strength of the magnetic field, precise alignment and the like are not required when the shift position detecting device 2 is assembled. The process can be reduced.

  The shift position detection device 2 is not limited to the shift unit 1 and may be installed on, for example, a brake pedal, an accelerator pedal, a steering shaft, or the like as long as it has a shaft 3.

[Second Embodiment]
FIG. 8 is a schematic perspective view showing a shift position detecting apparatus according to the second embodiment of the present invention.

  The shift position detection device 2A further includes a speed reducer 22 in addition to the configuration of the shift position detection device 2 of the first embodiment. The speed reducer 22 is configured by meshing a gear 22 a connected to the shaft 3 and a gear 22 b connected to the magnet 21. The speed reducer 22 sets the number of teeth of the gear 22a to be smaller than the number of teeth of the gear 22b, reduces the rotation angle of the shaft 3 by the gear ratio of the gear 22a and the gear 22b, and transmits it to the magnet 21.

(Effect of the second embodiment)
According to the second embodiment described above, since the rotation angle of the shaft 3 is reduced by the gear ratio of the gear 22a and the gear 22b and transmitted to the magnet 21, the rotation angle cycle of the magnetic sensor unit 20 is obtained. The position of the rotation angle of the shaft 3 of 180 ° or more can be detected.

  Further, the rotation angle of the shaft 3 can be detected more precisely by reversing the gear ratio.

  The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from or adjusting the technical idea of the present invention.

DESCRIPTION OF SYMBOLS 1 ... Shift unit, 2, 2A ... Shift position detection apparatus, 3 ... Shaft, 4 ... Shift lever, 5 ... Shift gate, 6 ... Shift panel, 7 ... Shift position display part, 15 ... Rotation angle, 20 ... Magnetic sensor unit , 21 ... Magnet, 21a ... N pole, 21b ... S pole, 22 ... Reduction gear, 22a, 22b ... Gear, 30 ... Connecting member, 70a-70e ... Shift position, 81 ... Storage part, 82 ... Output part, 200 ... Circuit board, 200a-200d ... MR sensor, 800 ... MR sensor output receiving means, 801 ... shift position detecting means, 810 ... shift position information,

Claims (3)

A magnet arranged with respect to the rotation axis such that the direction of the magnetic field changes with rotation of the rotation axis;
A magnetic sensor arranged to output a signal in accordance with the magnetic field of the magnet and to switch a signal to be output when the rotation axis is at a predetermined rotation angle;
Detecting means for arranging a plurality of magnetic sensors so that rotation angles at which signals output from the magnetic sensors are switched are different, and detecting an angle range of the rotating shaft according to a combination of signals output from the plurality of magnetic sensors; Rotation detection device.   The rotation detection device according to claim 1, further comprising a speed reducer that transmits a rotation angle of the rotation shaft and a rotation angle of the magnet in a magnetic field direction at a predetermined ratio. The magnet is formed in a flat plate shape and is magnetized so that a magnetic field is generated parallel to the surface,
The rotation detection device according to claim 1, wherein the magnetic sensor is arranged in parallel to a surface of the magnet.

Images