JPH0943260A - Mr element type rotation sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an MR element type rotation sensor capable of detecting a POS signal having small change of an output level and detecting an REF signal even if a magnetic interference is effected from the REF protrusion of a signal rotor. SOLUTION: A gear 14 for REF is disposed between a first gear 12 and a second gear 13 for POS, and the protrusions 15 of the gear 12 and the protrusions 16 of the gear 13 are formed with the deviation of the phase of P/2 from each other at a pitch P. A protrusion 17 for REF is formed oppositely to the gear 14, a PS detecting MR element 18 is formed oppositely to the gear 12, a POS detecting MR element 19 is formed oppositely to the gear 13, and REF detecting MR elements 20, 21 are formed at a pitch P/2 oppositely to the gear 14.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotation sensor,
In particular, the present invention relates to an MR element type rotation sensor having a signal rotor attached to a rotating body and an MR element arranged so as to face the signal rotor.

[0002]

2. Description of the Related Art As a conventional MR element type rotation sensor,
Japanese Patent Laid-Open No. 6-137891 discloses that the rotation of a gear having a POS protrusion indicating a rotation angle and the rotation of a gear having a REF protrusion indicating a reference position are opposed to each gear. The rotation angle signal and the reference position signal are obtained by the detection by the MR element arranged at the position.

[0003]

In the above-mentioned conventional rotation sensor, since the POS protrusion and the REF protrusion are arranged adjacent to each other, an M for POS signal detection is provided.
The R element receives the magnetic interference from the adjacent REF protrusion and receives the POS.
There is a problem that the output level of the signal fluctuates. The present invention has been made to solve the above-mentioned problems, and an MR capable of detecting a POS signal and a REF signal with a small output level fluctuation even when receiving magnetic interference from a REF protrusion.
An object is to provide a device type rotation sensor.

[0004]

The MR element type rotation sensor of the present invention has been made in view of the above-mentioned problems, and is attached to a rotating body and shows an SOS projection indicating a rotation angle and a reference position. A signal rotor having REF protrusions formed thereon, and an M arranged at a position facing each protrusion.
An MR element having an R element and a bias magnet disposed across the MR element on the opposite side of the signal rotor, and a detection means for detecting the midpoint potential of two MR elements connected in series as a rotation signal. In the rotation sensor, the signal rotor includes a POS first gear having a POS first protrusion indicating a rotation angle, a POS second gear having a POS second protrusion, and a REF protrusion indicating a reference position. Have REF
The POS first protrusion and the POS second protrusion have the same pitch P, and are arranged with a pitch shift of λP (0 <λ <1). The REF protrusion is the POS first protrusion. It is sandwiched between the protrusion and the second protrusion for POS. Furthermore, one MR element is provided at each of the same positions facing the first POS projection and the second POS projection, and at the same pitch P as facing the REF projection.
A plurality of are arranged in.

That is, the object of the present invention is, as described in the claims, to detect the change of the magnetic field by the magnetic rotating body opposite to the bias magnet as the rotation signal at the midpoint potential of the MR element. In the MR element type rotation sensor for outputting the angle signal and the reference signal of the rotating body by the detecting means, the first angle signal displaying means and the first angle signal means formed at the pitch P provided on the rotating body. ΛP (0 <λ <with respect to the first angle signal display means at the pitch P coaxially with
1) second angle signal display means formed by shifting the phase, and reference position signal display means formed coaxially between the first angle detection means and the second angle detection means, Bias magnets provided close to the first and second angle signal display means and the reference position signal display means in the radial direction of the magnetic rotating body are opposed to the first and second angle signal display means, respectively. The angle detecting MR element sandwiched between the bias magnet and the reference position signal display means, and sandwiched between the bias magnet and the first and second MR elements. This is achieved by an MR element type rotation sensor characterized by having a plurality of reference position detecting MR elements formed with a phase difference of pitch P with respect to the angle signal display means.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The principle of the present invention will be described below with reference to FIGS. First, a process in which the MR element for POS detection receives magnetic interference by the REF protrusion and the output level thereof changes will be described. FIG. 1 is a plan view showing the basic principle of the MR element type rotation sensor of the present invention, FIG. 2 is a partial front view thereof, and FIG. 3 is a view showing the same wiring circuit. As shown in FIGS. 1 and 2, the POS gear 1 and the REF gear 2 are arranged adjacent to each other. The gear 1 and the gear 2 are provided with a POS protrusion 3 and a REF protrusion 4, respectively. The POS detection MR element 5 is provided at a position facing the gear 1.
And 6, and M for REF detection at a position facing the gear 2.
R elements 7, 8 are arranged, and these MR elements 5, 6, 7,
A bias magnet 9 is provided on the back surface of 8. Each MR
Since the element has resistance temperature characteristics, M for POS detection
The R elements 5 and 6, and the REF detecting MR elements 7 and 8 are connected in series as shown in FIG. 3, and the midpoint potential is measured and used as a rotation signal, so that the resistance value changes depending on the temperature. The effects are offset. Further, in order to increase the detection sensitivity, as shown in FIG. 2, when the formation pitch of the POS protrusions 3 is P, two MR elements 5 arranged in parallel in the rotation direction are provided.
The MR element 6 is arranged with a phase shift of P / 2. When the gears 1 and 2 to be detected rotate, R
When the EF protrusion 4 is located away from the MR element 5 and the MR element 6, the magnetic flux density B ₅ and the magnetic flux density B ₆ applied perpendicularly to the MR element 5 and the MR element ₆ are as shown in FIG. To change. In the MR element made of a semiconductor typified by In-Sb, the relationship between the value of the magnetic flux density B applied perpendicularly to the MR element and the resistance value shows a change characteristic as shown in FIG. As a result, the sensor output Vp indicating the POS signal exhibits a sinusoidal change characteristic with a constant output peak value, as shown in FIG. 4B.

On the other hand, the REF projection 4 has the MR element 5
When passing through the vicinity of the MR element 5 and the MR element 6, the magnetic flux is pulled by the REF protrusion 4.
The value of the magnetic flux density applied to is decreased before and after the REF protrusion 4 passes, and the magnetic flux density B ₅ and the magnetic flux density B ₆ are shown in FIG.
It changes as shown in FIG. As a result, the sensor output Vp indicating the POS signal is output as shown in FIG.
The value does not become constant but changes while fluctuating.

<First Embodiment> FIGS. 7 and 8 are views showing the configuration of a rotation sensor according to a first embodiment of the present invention. In FIG. 7 and FIG. 8, the signal lo
The controller 11 includes a first POS gear 12, a second POS gear 13, and a REF gear 14.
The gear 14 has a structure sandwiched between a first POS gear 12 and a second POS gear 13. First protrusions 15 for POS are formed at a pitch P on the first gear 12 for POS. The second gear 13 for POS has the same shape as the first gear 12 for POS and has a first protrusion 16 for POS. As shown in FIG. 8, the first for POS
The gear 12 and the second gear 13 for POS have a protrusion pitch P.
Are arranged in parallel with each other with a phase difference of P / 2. Further, the REF gear 14 is formed with a REF projection 17 indicating a reference position. An POS detecting MR element 18 is arranged at a position facing the POS first gear 12,
Another POS is provided at a position facing the second gear 13 for the OS.
An MR element 19 for detection is provided. The MR element 18 and the MR element 19 are arranged in the same phase with respect to the rotation direction. Further, the REF detecting MR elements 20 and 21 are arranged at positions facing the REF gear 14, and the two MR elements 20 and 21 arranged in parallel in the rotation direction are P / 2.
It is arranged with the phase shifted in the rotational direction only. A bias magnet 2 is provided on the back surface of the MR elements 18, 19, 20 and 21.
2 are arranged.

The MR elements 18 to 21 have resistance temperature characteristics. For example, in the case of an In-Sb semiconductor thin film MR element, if the resistance value at a temperature of 25 ° C. is 1, then
It becomes about 7 at 0 ° C and about 0.2 at 150 ° C. As shown in FIG. 9, POS detection MR elements 18 and 19 are connected in series, and the midpoint potential Vp thereof is used as a rotation angle signal. Similarly, the MR elements 20 and 21 for REF detection are connected in series, and the midpoint potential Vr thereof is used as a reference position signal.

The signal rotor 11 is made of a material having a high magnetic permeability such as pure iron. It is manufactured by pressing pure iron powder, compression molding, and sintering. Since pure iron is easily corroded, surface treatment such as zinc plating or nickel plating is applied depending on the usage environment. Further, a material having a high magnetic permeability and a high corrosion resistance such as an electromagnetic stainless material may be used. In that case, surface treatment becomes unnecessary.
The signal rotor 11 of this embodiment is the first for POS.
Gear 12, second POS gear 13 and REF gear 1
4 may be formed separately, and then assembled by welding, or may be integrally attached to a rotary shaft (not shown). Alternatively, the signal rotor 11 including the rotating shaft may be manufactured as one component.

The MR elements 18 to 21 are types of magnetic devices whose resistance value changes depending on the magnitude of magnetic flux density, and are represented by semiconductors represented by In-Sb and Ni-Fe. It is roughly divided into ferromagnetic materials. The resistance value of the semiconductor MR element changes according to the magnitude of the magnetic flux density of the magnetic field perpendicular to the element, whereas the ferromagnetic MR element changes according to the magnitude of the magnetic flux density of the magnetic field parallel to the element. There is a big difference in that the resistance value changes. A rotation sensor of a type in which a bias magnet is arranged on the back surface of the MR element to detect the rotation of the gear has a relatively large resistance change rate of about 5% per 100 gauss, and
It is preferable to use a semiconductor MR element having no limitation on the applied magnetic flux density B. In this embodiment, an In-Sb semiconductor thin film is used.

For the bias magnet 22, an appropriate magnet material is selected and used according to its operating temperature environment, detection air gap, and the like. In the case of a consumer-use rotation sensor that has a low operating temperature and a narrow air gap, it is desirable to use a ferrite magnet or an alnico magnet for cost reduction. Also,
In the case of a rotation sensor for an automobile having a high operating temperature of 120 ° C. or more and a relatively wide air gap, an Nb-Fe-B magnet or an Sm-Co magnet having a large energy product is often used.

The first protrusion 15 for POS and the second protrusion 15 for POS
The relationship of the protrusions 16 is arranged with a phase shift of P / 2 with respect to the rotation direction. Also, the first gear 12 for POS
The second gear 13 for POS and the POS second gear 13 are formed in the same shape using the same material. Therefore, the REF protrusion 17 is PO
When it is located away from the S detection MR elements 18 and 19, as shown in FIG. 10A, the magnetic flux densities B ₁₈ and B applied perpendicularly to the MR elements 18 and 19 are obtained.
_{In the case of 19} , almost the same waveform changes with the phase shifted by P / 2. As a result, as shown in FIG.
It is possible to obtain the POS signal output Vp corresponding to the rotation and having no change in the output peak value.

On the other hand, the REF protrusion 17 is the MR for POS detection.
When passing through the vicinity of the elements 18 and 19, the MR elements 18 and 19 are affected by the REF projection 17, and the magnitude of the magnetic flux density applied before and after the REF projection 17 passes is reduced. However, since the MR elements 18 and 19 are arranged at the same position with respect to the rotation direction, the corresponding signals from the REF protrusion 17 can be received at substantially the same level with no time delay. Therefore, the magnetic flux densities B ₁₈ and B ₁₉ applied to the MR elements 18 and ₁₉ change as shown in FIG. As a result, in the POS signal output Vp, the peak value of the output hardly changes as shown in FIG.

Further, the REF detecting MR elements 20 and 21 receive magnetic interference from the POS first protrusion 15 and the POS second protrusion 16. However, the MR elements 20 and 21 have P
Similar to the phase shift between the OS first protrusion 15 and the POS second protrusion 16, the MR element 20 is arranged with a phase shift of P / 2 in the rotational direction, and the MR element 20 causes magnetic interference from the POS first protrusion 15. The MR element 21 is affected by the magnetic interference from the POS second protrusion 16 at substantially the same level. Therefore, the magnetic flux densities B ₂₀ and B ₂₁ applied to the REF detecting MR elements ₂₀ and ₂₁ change as shown in FIG. As a result, FIG.
As shown in (b), the waveform of the REF signal output Vr is P
The influence of the magnetic interference of the OS first protrusion 15 and the POS second protrusion 16 is hardly seen.

Further, MR elements 18 and 19 for POS detection
Are arranged at the same position with respect to the rotation direction. Therefore, regardless of the pitch P at which the POS first protrusions 15 and the POS second protrusions 16 are formed, the POS first protrusions 15 and P
If the OS second protrusions 16 are arranged with a phase shift of P / 2, the same element can be used.

<Second Embodiment> A second embodiment of the present invention will be described with reference to FIGS. Signal rotor 31
Has a POS first slit 32 and a POS second slit 33 formed therein, and a REF slit 34 is formed between the POS first slit 32 and the POS second slit 33. Similar to the first embodiment, the POS
The first slit 32 for POS and the second slit 33 for POS are
They are arranged with a phase shift of P / 2 of the formed pitch P. Further, the MR elements 18 to 21 and the bias magnet 22 are arranged at the same relational positions as in the first embodiment.

The signal rotor 31 is press-molded and is made of a stainless material which does not require surface treatment. It is desirable that the signal rotor 31 has a plate thickness of about 1 mm in order to secure the amount of change in the magnetic flux density and the ease of forming by pressing.
Since 2, 33 and 34 can be processed and formed at the same time, the weight of the signal rotor can be reduced.

By rotating the signal rotor 31, the POS
The MR elements 18 and 19 for detection use the REF slit 34,
The REF detecting MR elements 20 and 21 receive magnetic interference from the POS slits 32 and 33, respectively. However, due to the same operation as in the first embodiment, the POS signal output Vp and the REF signal output Vr can obtain signals that are hardly affected by magnetic interference. In the present embodiment, the slit is used to indicate the reference position, but conversely, the remaining portion punched out of the slit may be used as the reference position.

<Third Embodiment> A third embodiment of the present invention will be described with reference to FIGS. Signal rotor 4
1 is the first gear for POS 12, P as in the first embodiment.
It is composed of the second OS gear 13 and the REF gear 14. The first POS gear 12 and the second POS gear 13 are
The phase is shifted by P / 4. With such a configuration, the sensitivity of the sensor is reduced, but the POS signal output Vp, which is hardly affected by the magnetic interference from the REF protrusion 17, is obtained by the same operation as in the first embodiment.
Can be obtained. In the first embodiment, the REF detecting MR elements 20 and 21 are arranged with a phase shift of P / 2 in the rotational direction. However, in the present embodiment, the phase is shifted by P, so that By the same operation as that of the first embodiment, it is possible to obtain the REF signal output Vr in which the influence of the magnetic interference from the POS first projection 15 and the POS second 216 is hardly seen.

As described above, according to the above-described embodiment, the signal rotor having the POS protrusion showing the rotation angle and the REF protrusion showing the reference position is used as the POS protrusion having the same protrusion forming pitch P. The first projection and the second POS projection are arranged with a phase shift of λP (0 <λ <1), and the REF projection is sandwiched between the first POS projection and the second POS projection. Further, by disposing two MR elements for detecting the POS signal, one each facing the first POS protrusion and the second POS protrusion, at the same position in the rotation direction, Even if the MR element for POS detection receives magnetic interference from the REF protrusion, it is possible to obtain the POS signal output Vp with almost no effect. It is possible to obtain the effect that the POS detection MR element having the same pattern can be used regardless of the formation pitch P of the POS protrusions. Further, by disposing two MR elements for detecting the REF signal with the phase shifted by P in the rotation direction, the MR element for REF detection becomes POS.
Even if it receives magnetic interference from the protrusion, it has almost no effect.
The effect that the EF signal output Vr can be obtained is obtained.

As shown in the first embodiment, λ = 0.5
With this, the sensitivity of the sensor can be increased. Further, in this case, even if the phase difference between the two MR elements for detecting the REF signal is set to P / 2, the influence of magnetic interference from the POS protrusion can be reduced. As a result, the reference position signal having a steeper rising characteristic can be obtained, and the reference position detection accuracy can be improved. As shown in the second embodiment,
It goes without saying that a similar effect can be obtained by using a slit instead of a projection as means for giving information on the rotation angle and the reference position to the rotor.

[0023]

According to the embodiment of the present invention, the PO by the POS protrusion which indicates the rotation angle of the signal rotor attached to the rotating body.
The S signal has an effect that it is possible to accurately obtain the output signal of the detection of the rotation angle and the reference position detection in which the output level fluctuates little even if the S signal is subjected to the magnetic interference from the REF protrusion indicating the reference position. Is.

[Brief description of drawings]

FIG. 1 is a plan view showing the basic principle of an MR element type rotation sensor.

FIG. 2 is a partial front view showing the basic principle of an MR element type rotation sensor.

FIG. 3 is a diagram showing a wiring circuit of the MR element type rotation sensor of FIGS. 1 and 2;

FIG. 4 is a diagram showing change characteristics of the magnetic flux density (a) and the output voltage (b) of the MR element type rotation sensor of FIGS. 1 and 2 when the REF protrusion is separated from the MR element.

FIG. 5 is a diagram showing change characteristics of magnetic flux density (a) and output voltage (b) of the MR element type rotation sensor of FIGS. 1 and 2 when the REF protrusion and the MR element are close to each other.

FIG. 6 is a characteristic diagram showing the relationship between the value of magnetic flux density applied perpendicularly to the MR elements of FIGS. 1 and 2 and the resistance value.

FIG. 7 is a plan view showing the configuration of the MR type rotation sensor according to the first embodiment of the present invention.

FIG. 8 is a partial front view showing the configuration of the MR type rotation sensor according to the first embodiment of the present invention.

FIG. 9 is a diagram showing a wiring circuit of the MR element type rotation sensor according to the first embodiment of the present invention.

FIG. 10 is a diagram showing change characteristics of magnetic flux density (a) and output voltage (b) of the MR element type rotation sensor according to the first embodiment of the present invention.

FIG. 11 is a diagram showing changes in magnetic flux density (a) and output voltage (b) of the MR element type rotation sensor according to the first embodiment of the present invention.

FIG. 12 is a diagram showing change characteristics of magnetic flux density (a) and output voltage (b) of the MR element type rotation sensor according to the first embodiment of the present invention.

FIG. 13 is a plan view showing a configuration of an MR type rotation sensor according to a second embodiment of the present invention.

FIG. 14 is a partial front view showing the configuration of the MR type rotation sensor according to the second embodiment of the present invention.

FIG. 15 is a plan view showing a configuration of an MR type rotation sensor according to a third embodiment of the present invention.

FIG. 16 is a partial front view showing the configuration of an MR type rotation sensor according to a third embodiment of the present invention.

[Explanation of symbols]

1 ... POS gear 2 ... REF gear 3 ... POS protrusion 4 ... REF protrusion 5, 6 ... POS detection element 7, 8 ... REF detection element 9, 22 ... Bias magnet 11, 31, 41 ... Signal rotor 12 ... POS first gear 13 ... POS second gear 14 ... REF gear 15 ... POS first protrusion 16 ... POS second protrusion 17 ... REF protrusion 18, 19 ... POS detection MR element 20, 21 ... R
MR element for EF detection 32 ... POS first slit 33 ... POS second slit 34 ... REF slit Vp ... POS signal output Vr ... REF signal output

Claims (4)

[Claims] 1. An MR element for outputting an angle signal and a reference signal of the rotating body by a detecting means for detecting a change of a magnetic field by a magnetic rotating body opposed to a bias magnet as a rotation signal at a midpoint potential of the MR element. In the rotary sensor, the first angle signal display means formed at the pitch P provided on the rotating body, and λP (with respect to the first angle signal display means at the pitch P coaxially with the first angle signal means. 2nd angle signal display means formed by shifting the phase by 0 <λ <1), and a reference position signal sandwiched between the first angle detection means and the second angle detection means and formed coaxially. Display means, a bias magnet provided in the radial direction of the magnetic rotating body in proximity to the first and second angle signal display means and the reference position signal display means, and the first and second angle signal display Facing each of the means,
And an angle detection M sandwiched between the bias magnet and
A plurality of references that are formed between the R element and the reference position signal display means and are sandwiched between the bias magnet and the first and second angle signal display means with a phase difference of pitch P. An MR element type rotation sensor, comprising an MR element for position detection. 2. The MR element type rotation sensor according to claim 1, wherein the angle signal display means has at least one of a protrusion and a slit. 3. The second angle signal display means includes the λ
The MR element type rotation sensor according to claim 1, wherein λ = 0.5 at a phase shift of P. 4. The plurality of reference position detecting MR elements,
The phase difference is formed with a pitch of 0.5 P with respect to the rotating direction of the rotating body.
An MR element type rotation sensor according to the above item.