JP2009244044A - Magnetic rotational position detection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetic rotational position detection device having a small size on a rotational plane on which one of a first magnet and a magnetic detection means rotates with respect to the other. <P>SOLUTION: A magnetic rotational position detection device 4 comprises: a rotary magnet 6 that rotates according to lever operation of a select lever; a bias magnet 7 for generating a bias magnetic field therearound; and an MR sensor 10 for detecting a rotational position of the rotary magnet 6 by detecting a synthetic magnetic field of these magnets 6, 7. The bias magnet 7 is disposed on the back face position of the MR sensor 10 (magnetic detection unit 8). The bias magnet 7 is disposed next to the MR sensor 10 (magnetic detection unit 8) in the Z- axis direction. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a magnetic rotation position detection device that detects a rotation operation position of an operation unit by magnetism.

  2. Description of the Related Art Conventionally, in an operation system (operation device) used when operating various devices and apparatuses, there is a rotation operation type in which an operation action is performed by rotating an operation unit. When detecting the rotational operation position (rotational operation angle) of the operation unit in this rotational operation system, a rotational position detection device capable of detecting the rotational operation position of the operation unit is attached to this type of operation system. As this rotation detection device, for example, a magnetic type that detects the rotation operation position of the operation unit using a magnetic detection element is widely used. In this magnetic rotational position detection device, when one of the magnetic detection element and the magnet is attached to the operation part side, and the other is attached to the fixed part side that rotatably supports the operation part, the operation part is operated. The relative positional relationship between the magnet and the magnetic detection element changes, and the magnetic field applied from the magnet to the magnetic detection element changes. By detecting this magnetic field change with the magnetic detection element, the rotational operation position of the operation unit Is detected.

  This magnetic rotational position detection device includes a two-magnet type that generates a more suitable magnetic field using two magnets. This type of two-magnet type is disclosed in, for example, Patent Document 1. 8 and 9 show a magnetic rotational position detection device 81 of Patent Document 1. The magnetic rotational position detection device 81 includes a rotary magnet (counter magnet) that is attached to an operation unit 82 and generates a main magnetic field. ) 83, a bias magnet 84 that is attached to a fixed portion (not shown) and generates an auxiliary magnetic field (bias magnetic field) for the rotary magnet 83, and is also provided in the fixed portion and these magnets 83, 84. An MR sensor (magnetoresistance sensor) 85 for detecting the combined magnetic field is provided. In the case of the two-magnet type, variations in the magnetic field applied to the MR sensor 85 can be varied, so that the position detection characteristics of the magnetic rotational position detection device 81 can be improved.

The rotary magnet 83 of Patent Document 1 has a cylindrical shape with a reduced diameter, and is attached in a direction to rotate along its circumferential direction when the operation unit 82 is operated. Further, the bias magnet 84 has a circular ring shape extending along the rotating direction of the rotary magnet 83, thereby arranging the rotary magnet 83 from the periphery. The MR sensor 85 is disposed between the rotary magnet 83 and the bias magnet 84 on the rotation plane of the rotary magnet 83 (the plane in the direction of the arrow in FIG. 8), and is a combined magnetic field generated by the magnets 83 and 84 located on both sides of the MR sensor 85. The rotation operation position of the operation unit 82 is determined by detecting the magnetic field direction.
JP 2006-38821 A

  However, since the technique of Patent Document 1 arranges the MR sensor 85 between the rotary magnet 83 and the bias magnet 84 arranged side by side along the rotation plane direction, the MR sensor 85 is arranged in the rotation plane direction. It is necessary to prepare a space to do. Therefore, in the magnetic rotational position detection device 81 in which the magnets 83 and 84 and the MR sensor 85 have such a positional relationship, the magnets 83 and 84 and the MR are equivalent to the space for arranging the MR sensor 85 in the rotation plane direction. There is a problem that the size of the device group consisting of the sensors 85, that is, the magnetic rotational position detecting device 81, is increased in the direction of the rotational plane.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a magnetic rotational position detecting device capable of reducing the size of the device on the rotating plane when one of the first magnet and the magnetic detecting means rotates with respect to the other. There is.

  In order to solve the above problems, in the present invention, a first magnet provided on one of the operation part and its support part, a second magnet provided on the other of these and generating a bias magnetic field, and the other And a magnetic detection means for detecting a combined magnetic field generated by the two magnets, and when the operation section is operated, the first magnet and the magnetic detection means on the operation section side Is rotated about the axis of the first magnet with respect to the support side, and the change of the combined magnetic field due to the rotation is detected by the magnetic detection means, whereby the operation position of the operation unit is In the magnetic rotational position detecting device for detecting the magnetic field, the magnetic detection means is arranged at a position adjacent to the first magnet in the direction orthogonal to the axis, There is a gist in that a second magnet on the back surface position of the magnetic detection means.

  According to this configuration, since the second magnet is disposed at the back surface position in the axial direction of the magnetic detection means, in this case, it is not necessary to provide an arrangement space for the second magnet in the direction orthogonal to the axial center of the first magnet. Therefore, it is possible to reduce the apparatus size in the direction perpendicular to the axis of the magnetic rotational position detection device by the amount that the arrangement space of the first magnet can be omitted in the direction perpendicular to the axis of the second magnet. .

The gist of the present invention is that the magnetic detection means is disposed at an end position near the second magnet in the axial direction.
According to this configuration, as a result of conducting an experiment for actually measuring the detection output of the magnetic detection means, the detection output of the magnetic detection means is more linear when the magnetic detection means is disposed at the end position near the second magnet in the axial direction. In this state, a magnetic field that can be applied to the magnetic detection means is applied. Therefore, if the magnetic detection means is arranged at the end position closer to the second magnet in the axial direction, a more accurate linear output can be obtained, and the rotational position can be detected with higher accuracy. .

The gist of the present invention is that the coercive force ratio obtained by dividing the coercive force of the first magnet by the coercive force of the second magnet is set to a value lower than 1.
According to this configuration, as a result of conducting an experiment for actually measuring the detection output of the magnetic detection means, if the coercive force ratio between the first magnet and the second magnet is set to a value lower than 1, the detection output of the magnetic detection means is The state is given to the magnetic detection means that can be more linear. Therefore, if the coercive force ratio of the two magnets is set to be lower than 1, it is possible to obtain a more accurate linear output and to detect the rotational position with higher accuracy.

  In the present invention, half of the first magnet is magnetized to the N pole and the other half is magnetized to the S pole in the orthogonal plane of the axis, and the second magnet is opposite to the side facing the first magnet. The main point is that the magnetization is switched between the two sides.

  According to this configuration, as a result of conducting an experiment for actually measuring the detection output of the magnetic detection means, if the first magnet and the second magnet have such a magnetization pattern, the detection output of the magnetic detection means becomes more linear. A state is given to the possible magnetic detection means. Therefore, if these magnets are used as the above magnetized pattern, it is possible to obtain a more accurate linear output and to detect the rotational position with higher accuracy.

  According to the present invention, the device size can be reduced in the rotation plane when one of the first magnet and the magnetic detection means rotates with respect to the other.

Hereinafter, an embodiment of a magnetic rotational position detector embodying the present invention will be described with reference to FIGS.
As shown in FIG. 1, an automatic transmission type vehicle 1 is provided with a select lever 2 movably with respect to a vehicle body 3 as a lever for operating an automatic transmission (automatic transmission). The select lever 2 is, for example, a rotary operation type that can be rotated about a lever base end, for example, a parking range (P range), a reverse range (R range), a neutral range (N range), a drive Each range position such as a range (D range), a second range (2 ranges), and a first range (1 range) can be selectively operated. The select lever 2 corresponds to the operation unit, and the vehicle body 3 corresponds to the support unit.

  As shown in FIGS. 2 and 3, between the select lever 2 and the vehicle body 3, a non-contact type rotational position detection device 4 that detects the rotational operation position of the select lever 2 in a non-contact manner is assembled. As the non-contact rotational position detection device 4 of this example, a magnetic rotational position detection device 4 that uses a magnetic sensor to check the rotational operation position of the select lever 2 is employed. In this magnetic rotation position detection device 4, a rotary magnet 6 that generates a main magnetic field in a sensor position detection environment is attached to a rotation shaft 5 of a select lever 2 so as to be integrally rotatable. The rotary magnet 6 has a circular ring shape, and is attached so that the central axis L1 has the same axis center with respect to the rotary shaft 5 of the select lever 2. In the plane, half of them are magnetized with N poles and the other half with S poles. The rotary magnet 6 rotates in synchronization with the select lever 2 when the select lever 2 is operated. The rotary magnet 6 corresponds to the first magnet, the central axis L1 corresponds to the axis, and the XY plane corresponds to the orthogonal plane.

  On the other hand, a bias magnet 7 that generates a bias magnetic field in a sensor position detection environment is fixed to the vehicle body 3. The bias magnet 7 is formed in a substantially flat plate shape, and the surface opposite to the rotary magnet 6 is magnetized to the N pole, and the surface facing the rotary magnet 6 is magnetized to the S pole. The bias magnet 7 cooperates with the rotary magnet 6 to generate a combined magnetic field in the sensor position detection environment. When the rotary magnet 6 rotates, the direction of the magnetic field applied to the bias magnet 7 by the rotary magnet 6 changes. As a result, the magnetic field direction of the combined magnetic field generated in cooperation with the rotary magnet 6 and the bias magnet 7 changes. The bias magnet 7 corresponds to the second magnet.

  A magnetic detection unit 8 is attached and fixed to the vehicle body 3 as a sensor component of the magnetic rotational position detection device 4. The magnetic detection unit 8 is provided with a substrate 9 for mounting a sensor. An MR sensor (magnetic resistance sensor) 10 is provided as a magnetic sensor of the magnetic rotational position detection device 4 on the mounting surface which is the surface side of the substrate 9. Has been implemented. As shown in FIG. 4, the MR sensor 10 is composed of a circuit in which four magnetoresistors R1 to R4 are assembled in a bridge shape. The potential difference from the midpoint potential is output as a sensor signal (voltage signal) Vout. The MR sensor 10 detects the direction of the magnetic field applied to itself on the detection surface 11 and outputs a sensor signal Vout having a value corresponding to the detected magnetic field direction. Note that the MR sensor 10 of this example detects the magnetic field direction of the combined magnetic field generated by the rotary magnet 6 and the bias magnet 7. The MR sensor 10 corresponds to magnetic detection means.

  Further, as shown in FIG. 5, the sensor signal Vout of the MR sensor 10 is output as a signal value having a sinusoidal waveform with respect to the change in the magnetic field direction of the detected magnetic field, and one cycle is 180 degrees. By the way, in the rotational position detection device 4 using this type of MR sensor 10, the rotational position is generally detected by the substantially linear output portion Er (solid arrow region in FIG. 5) of the sensor signal Vout. If this approximate linear output portion Er is used when calculating the rotational position with the sensor output, the expression used at this time can be a simple proportional expression, so that the position calculation process can be simplified and the position calculation time can be reduced. This is because the time can be shortened.

  Further, when this rotational position detection is performed in a wide range (for example, a range of 85 degrees), when the rotary magnet 6 is rotated over this wide range, the sensor output of the MR sensor 10 is applied to the detection surface 11 of the MR sensor 10. A magnetic field that takes an output change of the substantially linear output portion Er shown in FIG. 5 must be applied. In other words, as can be seen from FIG. 5, the sensor output of the MR sensor 10 is in a linear output state when the magnetic field direction takes a value of about −22.5 degrees to about +22.5 degrees. For example, even if the rotary magnet 6 is rotated over a wide range, the magnetic field applied to the MR sensor 10 at this time is changed from the state of about −22.5 degrees to the state of about +22.5 degrees. Must take a magnetic field change that changes approximately proportionally. Further, in order to make the rotational position detection of the rotary magnet 6 more accurate, the non-linearity of the substantially linear output portion Er should be optimized so that the sensor output of the MR sensor 10 takes a more linear waveform. Must be planned. Therefore, in this example, even if the rotary magnet 6 is rotated over a wide range, the arrangement position, the arrangement interval of the rotary magnet 6, the bias magnet 7 and the MR sensor 10, so that the sensor output at this time takes a linear output, The characteristic value is characterized.

  This will be described. As shown in FIGS. 2 and 3, the MR sensor 10 (magnetic detection unit 8) is disposed adjacent to the rotary magnet 6 in the radial direction (the direction of the arrow W <b> 1 in FIG. 2). Yes. That is, for example, assuming that the horizontal direction in FIG. 2 is the X axis, the vertical direction in FIG. 2 is the Y axis, and the horizontal direction in FIG. 3 is the Y axis, the MR sensor 10 (magnetic detection unit 8) The rotary magnets 6 are arranged side by side in the direction (XY plane). Further, the rotary magnet 6 and the magnetic detection unit 8 are arranged side by side so that the bottom surfaces thereof are positioned at the same height, but the MR sensor 10 is + Z-axis from the end surface of the rotary magnet 6 by the thickness of the substrate 9. Arranged to float in the direction. The radial direction W1 corresponds to the direction perpendicular to the axis.

  Further, the bias magnet 7 of the present example is arranged offset to the side away from the rotary magnet 6 in the radial direction (arrow W1 direction in FIG. 2), and also in the axial direction (arrow W2 direction in FIG. 3). It is arranged offset on the far side. That is, the bias magnet 7 is offset with respect to the rotary magnet 6 in the + Y axis direction and is also offset in the −Z axis direction. Further, the bias magnet 7 is disposed at the back surface position of the magnetic detection unit 8 (substrate 9) in the axial direction of the rotary magnet 6 (the direction of the arrow W2 in FIG. 3). That is, the bias magnet 7 is arranged side by side with the MR sensor 10 (magnetic detection unit 8) in the Z-axis direction. The axial direction W2 corresponds to the axial direction.

  By the way, the rotary magnet 6 and the bias magnet 7 have a parameter called coercive force as the strength of each magnetic force. If these coercive forces have a strong value, the magnets 6 and 7 are in a state of being more strongly attracted to a magnetic material such as metal. In this example, when the coercive force of the rotary magnet 6 is Ha and the coercive force of the bias magnet 7 is Hb, the coercive force ratio Hx obtained by dividing the coercive force Ha of the rotary magnet 6 by the coercive force Hb of the bias magnet 7 (= Ha / Hb) is set to a value lower than “1”. The coercive force ratio Hx of this example is set to “0.82”, for example.

Next, sensor output characteristics of the MR sensor 10 in the magnetic rotational position detection device 4 of this example will be described.
As shown in FIG. 6, for example, when the rotary magnet 6 is rotated from −60 degrees to +60 degrees, the sensor signal Vout of the MR sensor 10 at this time is about −47. The output waveform is a substantially linear output in a rotation angle range Km of 85 degrees from 5 degrees to about +37.5 degrees. That is, the sensor output of the MR sensor 10 is a substantially linear output when the rotation angle of the rotary magnet 6 is within a rotation angle range Km of about -47.5 degrees to about +37.5 degrees and 85 degrees. Therefore, when the rotation angle of the rotary magnet 6 is calculated by the substantially linear output portion of the MR sensor 10, the rotary magnet 6 changes the rotation angle over a wide rotation angle range Km of about −47.5 degrees to about +37.5 degrees. It becomes possible to calculate.

Further, there is a characteristic value called output nonlinearity S (%) as a measure of how much nonlinearity (nonlinearity) the sensor output of the MR sensor 10 has. Here, an approximate value (ideal value) of the sensor signal (output voltage) Vout at each rotation angle of the rotary magnet 6 is Va, and a simulation value of the sensor signal (output voltage) Vout at each rotation angle of the rotary magnet 6 ( Measured value) is Vx, and the full-scale value that is the voltage difference between the sensor value Vmin at the lowest linear output and the sensor value Vmax at the highest linear output is F (= Vmax−Vmin). The output nonlinearity S is calculated by the following equation.
S = (Va−Vb) / F
If the output non-linearity S falls within a range of, for example, −0.5 to +0.5, it can be said that the linearity is basically high. Therefore, when the change waveform of the output nonlinearity S of this example is shown in FIG. 7, in the rotation angle range of about −47.5 degrees to about +37.5 degrees, which apparently takes a linear waveform in FIG. The output non-linearity S is in the range of approximately −0.5 to +0.5 (exactly, the value of the rotary magnet 6 except for the values around −47.5 degrees and about +37.5 degrees is excluded). Therefore, it can be said that the sensor output within the rotation angle range Km of about −47.5 degrees to about +37.5 degrees, which is the target range of angle detection, has very high linearity, and the rotation angle calculation of the rotary magnet 6 can be performed more. It can be said that it can be executed with high accuracy.

  In this example, in the magnetic rotational position detection device 4 that detects the rotation angle of the rotary magnet 6 by detecting the combined magnetic field of the rotary magnet 6 and the bias magnet 7 with the MR sensor 10, the back surface of the MR sensor 10. A bias magnet 7 was disposed at the position. Therefore, for example, compared to the case where the bias magnet 7 and the MR sensor 10 are arranged side by side in the radial direction of the rotary magnet 6, the arrangement space of the bias magnet 7 can be omitted in the radial direction. It is possible to reduce the device size in the radial direction of the rotary position detector 4.

  In this example, in addition to the arrangement relationship in which the MR sensor 10 is arranged at the radial position of the rotary magnet 6 and the bias magnet 7 is arranged at the rear surface position of the MR sensor 10, the axis of the rotary magnet 6 is also arranged. In this example, the coercive force ratio obtained by dividing the coercive force of the rotary magnet 6 by the coercive force of the bias magnet 7 while disposing the MR sensor 10 at a position near the direction end is lower than “1” (for example, “ 0.82 "). As a result, the arrangement relationship of these parts and the characteristic values of the parts are advantageous, and the output nonlinearity S of the sensor output of the MR sensor 10 is a wide rotation of about 85 degrees of about −47.5 degrees to about +37.5 degrees. It takes a state that falls within −0.5 to +0.5 over the angle range Km. Therefore, when the rotation angle of the rotary magnet 6 is calculated using the substantially linear output portion Er of the MR sensor 10, the rotation angle calculation can be performed with high accuracy over a wide range.

According to the configuration of the present embodiment, the following effects can be obtained.
(1) A bias magnet 7 that generates a combined magnetic field together with the rotary magnet 6 is disposed at the back surface position of the MR sensor 10. Accordingly, since it is not necessary to provide a space for arranging the bias magnet 7 in the radial direction of the rotary magnet 6, the apparatus size in the radial direction of the magnetic rotational position detecting device 4 can be reduced by an amount corresponding to the space omission.

  (2) The MR sensor 10 is disposed near the axial end of the rotary magnet 6 and the coercivity ratio between the rotary magnet 6 and the bias magnet 7 is set to a value lower than “1”. As a result, the output nonlinearity S of the sensor output of the MR sensor 10 falls within −0.5 to +0.5 over a wide rotation angle range Km of about −47.5 degrees to about +37.5 degrees and 85 degrees. Therefore, this rotation angle calculation can be performed with high accuracy over a wide range.

  (3) Of the rotary magnet 6 and the MR sensor 10 (bias magnet 7), the rotary magnet 6 is disposed on the select lever 2 side, and the MR sensor 10 is disposed on the vehicle body 3 side. Thus, since the MR sensor 10 is attached to the vehicle body 3 side that does not move when the lever is operated, no operating stress is applied to the MR sensor 10 when the lever is operated. Therefore, since it is difficult for the MR sensor 10 to fail or drop out, the effect of improving the durability of the magnetic rotational position detection device 4 is high.

(4) Since the rotary magnet 6 has a circular ring shape and the bias magnet 7 has a substantially flat plate shape, the shapes of the magnets 6 and 7 can be simplified.
Note that the embodiment is not limited to the configuration described so far, and may be modified as follows.

  The MR sensor 10 is not necessarily arranged at a position near the radial end of the rotary magnet 6, and the arrangement position thereof is not particularly limited, for example, an axial center position with respect to the rotary magnet 6.

The coercive force ratio between the rotary magnet 6 and the bias magnet 7 is not necessarily limited to a value lower than “1”, and may be changed as appropriate.
The rotary magnet 6 is not necessarily limited to the circular ring shape, and may have another shape such as a disk shape. Further, the shape of the bias magnet 7 is not limited to a substantially flat plate shape, and other shapes such as a cylindrical shape may be employed.

  The arrangement position of the MR sensor 10 only needs to be arranged in the radial direction with respect to the rotary magnet 6, and the arrangement position of the rotary magnet 6 in the axial direction is not particularly limited. Further, the bias magnet 7 is disposed at the back surface position of the MR sensor 10, and this position is centered with respect to the surface direction of the detection surface 11 of the MR sensor 10 (essentially, the center with respect to the MR sensor 10. ), But may be offset from the center position by a predetermined amount.

  The rotary magnet 6 is not disposed on the select lever 2 side, and the MR sensor 10 (bias magnet 7) is not disposed on the vehicle body 3 side, and this combination may be reversed.

  The mounting target of the magnetic rotational position detection device 4 is not necessarily limited to the range position detection of the select lever 2 but may be a neutral start switch, for example. The neutral start switch is capable of starting the engine only when the select lever is in the neutral position and the parking position.

  The mounting target of the magnetic rotational position detection device 4 is not necessarily limited to the vehicle 1. That is, as long as it is necessary to detect the rotational operation position when the operation unit is operated, the device and apparatus on which the magnetic rotational position detection device 4 is mounted are not particularly limited.

Next, technical ideas that can be grasped from the above-described embodiment and other examples will be described below together with their effects.
(1) The first magnet, the second magnet, and the magnetic detection means according to any one of claims 1 to 4, wherein the first magnet is assembled to the operation portion side, and the second magnet and the magnetic detection means Is assembled to the support portion side. According to this configuration, since the magnetic detection means is on the fixed side, the magnetic detection means does not have to move when the operation unit is operated. Therefore, since it is not necessary to apply stress acting on the operation unit to the magnetic detection means, it is possible to make it difficult for the magnetic detection means to fail.

  (2) In any one of claims 1 to 4 and the technical idea (1), the first magnet is formed in a circular ring shape, and the second magnet is formed in a plate shape. In this case, since the shape of these magnets may be a simple shape that is generally used, it is highly effective in simplifying the structure of the magnetic rotational position detection device.

The perspective view which shows the external appearance in the vehicle in one Embodiment. The top view which shows schematic structure of a magnetic type rotational position detection apparatus. The side view which shows schematic structure of a magnetic type rotational position detection apparatus. The circuit diagram which shows schematic structure of MR sensor. The output waveform figure which shows the output change with respect to the detection magnetic field of MR sensor. The wave form diagram which shows the output change of the sensor with respect to the rotation change of a rotary magnet. The wave form diagram which shows the change of the linearity with respect to the rotation change of a rotary magnet. The perspective view which shows schematic structure of the conventional magnetic type rotational position detection apparatus. Sectional drawing which shows schematic structure of the magnetic type rotational position detection apparatus similarly.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 2 ... Shift lever as an operation part, 3 ... Vehicle body as a support part, 4 ... Magnetic rotational position detection apparatus, 6 ... Rotary magnet as 1st magnet, 7 ... Bias magnet as 2nd magnet, 10 ... Magnetic detection MR sensor as means, L1 ... center axis as axis, W1 ... radial direction as axis orthogonal direction, W2 ... axis direction as axis, Ha, Hb ... coercivity, Hx ... coercivity ratio.

Claims (4)

A first magnet provided on one of the operating part and its support part, a second magnet provided on the other of these and generating a bias magnetic field, and a composite also provided on the other and generated by the two magnets Magnetic detection means for detecting a magnetic field, and when the operation portion is operated, the first magnet and the magnetic detection means on the operation portion side are more than the support portion side on the first magnet. In the magnetic rotational position detection device that detects the operation position of the operation unit by detecting the change of the combined magnetic field accompanying the rotation by the magnetic detection means.
The magnetic detection means is disposed at a position adjacent to the first magnet in the direction perpendicular to the axis, and the second magnet is disposed at a back surface position of the magnetic detection means in the axis direction of the first magnet. Magnetic rotational position detector.   2. The magnetic rotational position detection device according to claim 1, wherein the magnetic detection unit is disposed at an end position near the second magnet in the axial direction.   The magnetic rotational position according to claim 1 or 2, wherein a coercive force ratio obtained by dividing the coercive force of the first magnet by the coercive force of the second magnet is set to a value lower than one. Detection device.   Half of the first magnet is magnetized in the N-pole and the other half is magnetized in the orthogonal plane of the axis, and the second magnet is magnetized on the side opposite to the side facing the first magnet. The magnetic rotational position detection device according to any one of claims 1 to 3, wherein magnetism is switched.

Images