JP2004061458A - Rotation sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To univocally output a precise detection result irrespective of a detection range. <P>SOLUTION: This sensor is provided with: the first rotational angle detecting means 10L for outputting a detection signal of a prescribed period in response to rotational angle change of a detection object; the second rotational angle detecting means 10R for outputting a detection signal of the same period as that of the first rotational angle detecting means 10L in response to the rotational angle change of the detection object, and of which the phase is shifted by 1/4 of the period; and a rotational angle determining part 20 for determining the detection phase of the first rotational angle detecting means 10L based on whether a detection signal S2 acquired from the second rotational angle detecting means 10R exceeds an average level VM, when the detection signal S1 acquired from the the first rotational angle detecting means 10L is within a high linearity range, and for determining a rotational angle, based on the thus determined detection phase and the detection signal S1 from the the first rotational angle detecting means 10L. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a rotation sensor for detecting a change in the rotation angle of a detection target.
[0002]
[Prior art]
FIG. 6 and FIG. 7 show this kind of prior art. This rotation sensor is provided in, for example, an automobile, and detects a relative rotation angle between a steering shaft S formed by a driving shaft MS and a driven shaft SS connected via a torsion joint TJ and a vehicle body. , A core 1, a stator 2 and a rotor 3.
[0003]
The core 1 is formed in a large-diameter annular shape by an insulating magnetic material, and is attached to a reference plate 4. The stator 2 is formed in an annular shape from an insulating magnetic material, and is attached to the reference plate 4 in a state where the stator 2 is coaxial with the core 1 with a gap secured between the stator 2 and the inner peripheral surface of the core 1. It is. The stator 2 has a conductor 5, for example, a copper foil, and an excitation coil 6. The conductor 5 is affixed in a thin layer in the range of 180 ° on the outer peripheral surface of the stator 2. The exciting coil 6 is for forming a magnetic field between itself and the core 1 when energized. The rotor 3 is formed in a semi-cylindrical shape using a conductive material such as copper, copper alloy, aluminum, and aluminum alloy. The rotor 3 is arranged between the core 1 and the stator 2 such that the axis of the semi-cylinder matches the axis of the core 1 and rotates around the axis.
[0004]
In the rotation sensor configured as described above, when an alternating current flows through the exciting coil 6, an alternating magnetic field is formed between the core 1 and the stator 2. Here, in the rotation sensor, the strength of the magnetic field is different between the portion where the conductor 5 is provided and the portion where the conductor 5 is not provided in the stator 2, and the magnetic flux density is not along the circumferential direction. Become uniform. That is, in the portion where the conductor 5 is provided, an eddy current is induced in the conductor 5 and a magnetic field is formed in the opposite direction by the eddy current. Density decreases. As a result, a region Fa where the conductor 5 is present and the magnetic flux density is low and a region Fb where the conductor 5 is not present and the magnetic flux density is high are formed by 180 ° between the core 1 and the stator 2. become.
[0005]
When the stator 2 and the rotor 3 are relatively rotated with respect to such a non-uniform magnetic field along the circumferential direction, the area of the rotor 3 located in the region Fa having a small magnetic flux density and the region located in the region Fb having a large magnetic flux density are located. The ratio with the area to be changed gradually. For this reason, the magnitude of the eddy current induced in the rotor 3 changes according to the relative rotation angle between the stator 2 and the rotor 3, and the impedance of the exciting coil 6 changes accordingly. Therefore, for example, while the stator 2 is fixedly provided on the vehicle body side, the rotor 3 is connected to the steering shaft S, and when the rotation angle changes between the vehicle body side and the steering shaft S, the stator 2 and the rotor 3 are connected. By arranging relative rotation, it is possible to detect a change in the relative rotation angle between the vehicle body and the steering shaft S through a change in the impedance of the exciting coil 6.
[0006]
FIG. 8 is a graph showing detection results for a change in the relative rotation angle between the stator 2 and the rotor 3 in the above-described rotation sensor. As is clear from FIG. 8, according to the rotation sensor, it is possible to obtain a substantially triangular detection signal having a cycle of 360 °.
[0007]
[Problems to be solved by the invention]
By the way, in the above-mentioned rotation sensor, two values can be taken as a rotation angle for one detected value. Specifically, as illustrated in FIG. 8, when the detected value is V1, α1 and α2 are candidates for the rotation angle, and it is difficult to identify which of them is the rotation angle.
[0008]
In addition, when 0 ° (360 °) and 180 ° are detected in FIG. 8, as shown in FIGS. 6A and 6B, the edge of the conductor 5 provided on the stator 2 and the edge of the rotor 3 Are in proximity to each other. As described above, when the edge of the conductor 5 and the edge of the rotor 3 are close to each other, a change in the relative rotation angle between the two does not necessarily change the impedance of the exciting coil 6 linearly. Depending on the case, it may be difficult to expect high detection accuracy.
[0009]
In view of the above circumstances, an object of the present invention is to provide a rotation sensor that can uniquely output a highly accurate detection result regardless of a detection range.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, a rotation sensor according to claim 1 of the present invention comprises: first rotation angle detection means for outputting a detection signal of a predetermined period in accordance with a change in the rotation angle of a detection target; The second rotation angle detection means for outputting a detection signal having the same cycle as the first rotation angle detection means and having a phase shifted by 1/4 cycle in accordance with the angle change, and one of the rotation angle detection means. When the detection signal is within a preset output level range, the detection phase of one rotation angle detection means is determined based on the output level of the detection signal obtained from the other rotation angle detection means, and the determined detection is performed. A rotation angle determination unit that determines a rotation angle based on a phase and a detection signal obtained from the one rotation angle detection unit.
[0011]
That is, according to the present invention, regardless of the detection range, the detection signal obtained from one of the rotation angle detection means can be set to a predetermined output level range, for example, a high linearity range. By doing so, a highly accurate detection result can be obtained. Moreover, the two values obtained from the output result of one of the rotation angle detecting means are different from each other in the output level of the detection signal obtained from the other rotation angle detecting means. The output result of the angle detecting means can be uniquely determined.
[0012]
According to a second aspect of the present invention, there is provided the rotation sensor according to the first aspect, wherein the rotation angle detecting means is made of a magnetic material, and when the excitation coil is energized, the magnetic flux along the circumferential direction between the core and the core. A first rotation angle detecting element for forming a magnetic field having a non-uniform density, and an area formed of a conductive material and having an area crossing the non-uniform magnetic field when rotated relative to the first rotation angle detecting element. A second rotation angle detection element that moves so as to change the ratio, wherein the first rotation angle detection element and the second rotation angle detection element relatively rotate according to a change in the rotation angle of the detection target. And outputting a detection signal in accordance with an impedance change of the exciting coil based on a relative rotation of the first and second rotation angle detecting elements.
[0013]
Also, in the rotation sensor according to claim 3 of the present invention, the non-uniformity is obtained by disposing a conductor in a part of the first rotation angle detection element along a circumferential direction in the above-described claim 1 or 2. The magnetic field is formed as follows.
[0014]
According to a fourth aspect of the present invention, in the rotation sensor according to the third aspect, a conductor is continuously disposed within a range of 180 ° of the first rotation angle detecting element, and the second rotation The corner detecting element is formed in an arc shape having a size corresponding to the conductor.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, preferred embodiments of a rotation sensor according to the present invention will be described in detail with reference to the accompanying drawings.
[0016]
1 and 2 show a rotation sensor according to an embodiment of the present invention. Although the rotation sensor exemplified here is not explicitly shown in the drawing, it is provided in, for example, an automobile, and detects a relative rotation angle between the steering shaft and the vehicle body. Have. Since the two rotation angle detecting means 10 have the same configuration, hereinafter, the suffix "L" will be added to the configuration of the rotation angle detecting means 10 located on the left side in FIG. The configuration of the rotation angle detecting means 10 located on the side will be described with a suffix “R” attached.
[0017]
As shown in FIGS. 1 and 2, the rotation angle detecting means 10L, 10R includes support shafts 11L, 11R, cores 12L, 12R provided around the support shafts 11L, 11R, stators 13L, 13R, and rotors 14L, 14R. And
[0018]
The support shafts 11L and 11R are rotatably disposed with respect to the reference plates 15L and 15R, and have input gears 16L and 16R at ends protruding from the reference plates 15L and 15R. Note that the reference plates 15L and 15R are provided fixed to the housing 115.
[0019]
The cores 12L and 12R are formed in a cylindrical shape with a large diameter by using an insulating magnetic material, and are attached to the reference plates 15L and 15R in a state where the axis of the cylinder matches the axis of the support shafts 11L and 11R.
[0020]
The stators 13L and 13R are formed in an annular shape, and the reference plates 15L and 15R are coaxial with the cores 12L and 12R in a state where a gap is secured between the stators 13L and 13R. Attached and fixed. These stators 13L, 13R are formed by providing conductors 17L, 17R on coil cores 13aL, 13aR formed in an annular shape by an insulating magnetic material, and by providing exciting coils 18L, 18R. The conductors 17L, 17R are formed in a thin foil shape of about 0.2 mm from a metal such as copper, aluminum, silver, or the like, and have a 180 ° range with the same starting point on the outer peripheral surfaces of the stators 13L, 13R. It is affixed in layers to cover. The conductors 17L, 17R do not necessarily have to be attached to the outer peripheral surfaces of the stators 13L, 13R, but may be attached to the inner peripheral surfaces of the cores 12L, 12R. The excitation coils 18L and 18R are for forming an AC magnetic field between the core 12L and the coil core 13aL and between the core 12R and the coil core 13aR when an AC excitation current flows.
[0021]
The rotors 14L and 14R include disk-shaped bases 14aL and 14aR, and semi-cylindrical rotors 14bL and 14bR protruding along the axial direction from the outer peripheral edges of the bases 14aL and 14aR. Then, the rotors 14bL and 14bR are fixed to the support shafts 11L and 11R via the bases 14aL and 14aR, and rotate about the axes of the support shafts 11L and 11R between the cores 12L and 12R and the stators 13L and 13R. It is configured in. In the rotors 14L and 14R, at least the rotor portions 14bL and 14bR described above are formed of a conductive material such as copper, a copper alloy, aluminum, or an aluminum alloy.
[0022]
The two rotation angle detecting means 10L and 10R configured as described above mesh the individual input gears 16L and 16R directly or via appropriate gear trains. For example, as shown in FIG. The conductor 17L of the rotor 13L and the rotor portion 14bL of the rotor 14L are set facing each other over a range of 90 °, whereas the conductor 17R of the stator 13R and the rotor portion 14bR of the rotor 14R are set so as not to face each other. The phases of the rotors 14L, 14R with respect to the stators 13L, 13R are set so as to be shifted from each other by 90 °.
[0023]
The rotation sensor includes a rotation angle determination unit 20. The rotation angle determination unit 20 determines the rotation angle based on the detection signals when the detection signals are given from the rotation angle detection units 10L and 10R, and outputs the determined rotation angle to the outside. The principle of outputting a detection signal from each of the rotation angle detecting means 10L and 10R is as follows.
[0024]
First, in the rotation sensor configured as described above, when an AC current is applied to the excitation coils 18L, 18R of the rotation angle detection units 10L, 10R, an AC magnetic field is generated between the cores 12L, 12R and the stators 13L, 13R, respectively. It is formed. In this case, similarly to the conventional rotation sensor shown in FIG. 6, in the stators 13L and 13R, the portions where the conductors 17L and 17R are provided and the portions where the conductors 17L and 17R are not provided have different magnetic field strengths. Thus, a region Fa where the conductors 17L and 17R are present and the magnetic flux density is low and a region Fb where the conductors 17L and 17R are not present and the magnetic flux density is high are formed by 180 °.
[0025]
When the stators 13L, 13R and the rotors 14L, 14R are relatively rotated with respect to such a non-uniform magnetic field along the circumferential direction, the rotors 14L, 14R are located in the region Fa of the rotor portion 14bL, 14bR where the magnetic flux density is small. And the ratio of the area located in the region Fb where the magnetic flux density is large gradually changes. For this reason, the magnitude of the eddy current induced in the rotor portions 14bL and 14bR of the rotors 14L and 14R changes according to the relative rotation angle between the stators 13L and 13R and the rotors 14L and 14R. The impedance of the 18R also changes accordingly.
[0026]
FIGS. 3A and 3B are graphs showing detection results with respect to changes in the relative rotation angles between the stators 13L, 13R and the rotors 14L, 14R in the rotation angle detection means 10L, 10R described above. As is apparent from FIG. 3, the respective rotation angle detecting means 10L and 10R output the same substantially triangular detection signals S1 and S2 having a period of 360 °.
[0027]
Here, even in the rotation sensor of the present embodiment, since the configuration of each of the rotation angle detection means 10L and 10R is the same as that of the conventional rotation sensor shown in FIG. The rotation angle can take two values with respect to the detected value. Further, when the edges of the conductors 17L and 17R provided on the stators 13L and 13R and the edges of the rotors 14L and 14R are close to each other, a change in the relative rotation angle between the two necessarily changes the impedance of the exciting coils 18L and 18R linearly. However, high accuracy cannot be expected. This is because the magnetic flux density at the boundary between the low magnetic flux density area Fa and the high magnetic flux density area Fb formed between the cores 12L, 12R and the stators 13L, 13R does not fluctuate sharply, and is within a certain angle range. This occurs because there is a gradually changing area inside. That is, when the edge which is the circumferential end of the rotors 14L and 14R crosses the region where the magnetic flux density gradually changes, the amount of change (gradient) in the output signal level also becomes small, so that the corresponding signal peaks and valleys Is rounded. For example, in FIG. 3, in a range exceeding a high threshold level (for example, 4/5 level = VH) and a range below a low threshold level (for example, 1/5 level = VL), Deterioration of linearity becomes relatively significant.
[0028]
However, in the rotation sensor of the present embodiment, as described above, the two rotation angle detecting means 10L and 10R are set so that the phases of the rotors 14L and 14R with respect to the stators 13L and 13R are shifted from each other by 90 °. , A phase difference of 90 °, that is, a 1/4 cycle occurs in the detection signals S1 and S2.
[0029]
Therefore, according to the rotation sensor of the present embodiment, even if two rotation angles can be obtained for one detection value given from one rotation angle detection means, the other rotation angle detection means Depending on whether the given detection signal exceeds a predetermined threshold level (for example, 1/2 level = average level VM), it differs from each other, and if the output level of the other rotation angle detecting means is referred to, The rotation angle can be determined by specifying the detection phase of one rotation angle detection means.
[0030]
Further, when the detection signal given from one rotation angle detection means is in a range exceeding the high threshold level or below the low threshold level, the detection signal given from the other rotation angle detection means always becomes high. The range is between the threshold level and the low threshold level. In other words, according to the rotation sensor of the present embodiment, the detection signal given from either one of the rotation angle detection means always falls between the high threshold level and the low threshold level (hereinafter, referred to as a high linearity range). Value.
[0031]
Therefore, the rotation angle determination unit 20 solves the above-described problem by using the detection signals S1 and S2 output from these two rotation angle detection units 10L and 10R.
[0032]
FIG. 4 is a flowchart illustrating a processing procedure of the rotation angle determination unit 20 described above. Hereinafter, the processing contents of the rotation angle determination unit 20 will be described with reference to FIG. 4, and the characteristic parts of the present invention will be described in further detail. In the following, the rotation angle detecting means disposed on the left side in FIG. 1 is referred to as first rotation angle detecting means 10L, and the detection signal output from the first rotation angle detecting means 10L is referred to as S1 and the right. The rotation angle detection means disposed on the side is referred to as a second rotation angle detection means 10R, and the detection signal output from the second rotation angle detection means 10R will be described as S2. In the following description, it is assumed that the fluctuation range of the signal levels of the detection signals S1 and S2 is measured in advance, and VM, VH, and VL are set in accordance with the range. In this case, VM is an average level substantially in the middle of the signal fluctuation range, VH is about 4/5 level (high threshold level) of the signal fluctuation range, and VL is about 1/5 level (low threshold level) of the signal fluctuation range. is there. It is the same as above that the area between the high threshold level VH and the low threshold level VL is simply referred to as the high linearity range.
[0033]
First, the rotation angle determination unit 20 acquires the respective detection signals S1 and S2 from the first rotation angle detection unit 10L and the second rotation angle detection unit 10R (step S101), and detects the detection signals of the first rotation angle detection unit 10L. It is determined whether or not S1 is in the high linearity range (step S102). For example, as shown by V0 in FIG. 3A, when the detection signal S1 is in the high linearity range, the rotation angle is calculated based on the detection signal S1 (step S103). In this case, since the rotation angle is calculated based on the detection signal S1 in the high linearity range, it goes without saying that the calculation result becomes an accurate value. However, as described above, two rotation angles α01 and α02 corresponding to V0 are calculated from only the detection signal S1 of the first rotation angle detection unit 10L.
[0034]
Thereafter, the rotation angle determination unit 20 determines whether the detection signal S2 of the second rotation angle detection unit 10R is higher than the average level VM in order to specify the detection phase of the detection signal S1 given from the first rotation angle detection unit 10L. It is determined whether or not it is (step S104).
[0035]
In the determination in step S104, when the detection signal S2 of the second rotation angle detection means 10R is equal to or lower than the average level VM, it is specified that the detection phase is less than 180 ° as shown in FIG. Can be performed (step S105). Therefore, the rotation angle determination unit 20 determines the rotation angle as α01 based on the result calculated in step S103 and the detected phase specified in step S105, and can output this (step S106). , Step S112).
[0036]
On the other hand, when the detection signal S2 of the second rotation angle detection means 10R exceeds the average level VM in the determination in step S104, as shown in FIG. It can be specified as a range (step S107). Accordingly, the rotation angle determining unit 20 determines the rotation angle as α02 based on the result calculated in step S103 and the detected phase specified in step S107, and can output this (step S106). , Step S112).
[0037]
On the other hand, if it is determined in step S102 that the detection signal S1 of the first rotation angle detection unit 10L is not within the high linearity range, the procedure proceeds to step S108, and the procedure is performed based on the detection signal S2 of the second rotation angle detection unit 10R. Calculate the rotation angle. Here, when the detection signal S1 of the first rotation angle detection means 10L is not in the high linearity range, the detection signal S2 of the second rotation angle detection means 10R becomes high as shown by V9 in FIG. 3B, for example. Since the rotation angle is within the linearity range, the rotation angle can be accurately calculated. However, also in this case, two rotation angles α91 and α92 are calculated from only the detection signal S2 of the second rotation angle detection means 10R.
[0038]
After that, the rotation angle determination unit 20 determines whether the detection signal S1 of the first rotation angle detection unit 10L exceeds the average level VM in order to specify the detection phase of the detection signal S2 given from the second rotation angle detection unit 10R. It is determined whether or not it is (step S109).
[0039]
In the determination of step S109, when the detection signal S1 of the first rotation angle detection unit 10L is equal to or lower than the average level VM, as shown in FIG. ) Or 270 ° or more (less than 360 °) (step S110). Therefore, the rotation angle determination unit 20 determines the rotation angle as α91 based on the result calculated in step S108 and the detection phase specified in step S110, and can output this (step S106). , Step S112).
[0040]
On the other hand, if the detection signal S1 of the first rotation angle detection means 10L exceeds the average level VM in the determination in step S109, the detection phase is 90 ° or more and 270, as shown in FIG. It can be specified that the angle is within the range of less than ° (step S111). Therefore, the rotation angle determination unit 20 determines the rotation angle as α92 based on the result calculated in step S108 and the detected phase specified in step S111, and can output this (step S106). , Step S112).
[0041]
As described above, according to the rotation sensor of the present embodiment, even if two rotation angles can be taken for one detection value given from one rotation angle detection means, the other rotation angle can be obtained. The rotation angle can be determined by specifying the detection phase of one rotation angle detection means based on whether the detection signal given from the angle detection means exceeds the average level VM. In addition, according to the rotation sensor of the present embodiment, the detection signal given from either one of the rotation angle detection means is always a value in the high linearity range, so that the calculated rotation angle is independent of the detection range. High accuracy can always be expected. Therefore, for example, if a change in the relative rotation angle between the steering shaft and the vehicle body is input from one of the input gears, the change in the relative rotation angle between the steering shaft and the vehicle body is always uniquely detected with high accuracy regardless of the detection range. Will be able to
[0042]
Note that the detailed configuration of the rotation angle detecting means is not limited to the above-described embodiment. For example, the exciting coils 18L, 18R may be provided on the cores 12L, 12R, or the cores 12L, 12R and the stators 13L, 13R may be arranged in reverse. Further, the stators 13L and 13R may be connected to the support shafts 11L and 11R to form a rotor, while the rotors 14L and 14R may be fixed to form a stator. Since the non-uniform magnetic field is provided in the range of 180 °, the detection range can be set to 360 °, but it is not always necessary to provide the detection range in the range of 180 °. In this case, the period of the detection signal does not become 360 °, but the same operation and effect can be obtained by shifting the phase by １ ／ period.
[0043]
Further, the two rotation angle detecting means 10L and 10R are arranged side by side on the left and right. However, it is only necessary to output detection signals which are out of phase with each other by 1/4 cycle, and any arrangement can be adopted. It is also possible to provide them on the same axis, for example, as in a modification shown in FIG.
[0044]
The rotation sensor of the modified example shown in FIG. 5 is also provided in, for example, an automobile and detects the relative rotation angle between the steering shaft and the vehicle body similarly to the first embodiment. 10 is provided. Since the two rotation angle detecting means 10 have the same configuration, the suffix “U” and the suffix “U” in FIG. In the figure, the suffix "D" is added to the configuration of the rotation angle detecting means 10 located below, while the configuration common to both is described without the suffix.
[0045]
As shown in FIG. 5, the rotation angle detecting means 10U and 10D include a support shaft 11 which is common to the upper and lower parts, a core 12 which is common to the upper and lower parts provided around the support shaft 11, upper and lower individual stators 13U and 13D, and a common part which is upper and lower parts. It has a rotor 14 and is housed inside a housing 115.
[0046]
The support shaft 11 is provided so as to be rotatable around a predetermined axis with respect to the housing 115.
[0047]
The core 12 is formed in a large-diameter cylindrical shape with an insulating magnetic material, and is fixed to the housing 115 in a state where the axis of the cylinder coincides with the axis of the support shaft 11.
[0048]
The stators 13U and 13D are formed in an annular shape, and are attached and fixed to the reference plates 15U and 15D so as to be coaxial with the core 12 in a state where a gap is secured between the stators 13U and 13D. You. As is apparent from the figure, the upper reference plate 15U is attached to the lower rotation angle detecting means 10D via the lower stator 13D, and is fixed to the housing 115 via the lower reference plate 15D. ing.
[0049]
These stators 13U and 13D are formed by providing conductors 17U and 17D on coil cores 13aU and 13aD formed in an annular shape by an insulating magnetic material, and by providing exciting coils 18U and 18D. The conductors 17U and 17D are made of a metal such as copper, aluminum, silver or the like, and are formed in a thin foil shape of about 0.2 mm. Are affixed in layers so as to be shifted from each other by 180 °. The conductors 17U and 17D do not necessarily need to be attached to the outer peripheral surfaces of the stators 13U and 13D, and may be attached to the inner peripheral surface of the core 12. The exciting coils 18U and 18D are for forming an alternating magnetic field between the core 12 and the coil core 13aU and between the core 12 and the coil core 13aD when an alternating current is applied.
[0050]
The rotor 14 includes a disk-shaped base portion 14a and a semi-cylindrical rotor portion 14b protruding from an outer peripheral edge of the base portion 14a along the axial direction, and is supported via the base portion 14a. The rotor portion 14b is fixed to the shaft 11, and is configured to rotate around the axis of the support shaft 11 between the core 12 and the stators 13U and 13D. In the rotor 14, at least the rotor portion 14b described above is formed of a conductive material such as copper, copper alloy, aluminum, and aluminum alloy.
[0051]
When the relative rotation angle changes between the stators 13U, 13D and the rotor 14 from the rotation angle detecting means 10U, 10D configured as described above, each has a cycle of 360 ° as in the first embodiment. , The detection signals S1 and S2 having the same substantially triangular waveform and having phases shifted from each other by 90 ° are output.
[0052]
Although not explicitly shown in the figure, the rotation sensor is provided with a rotation angle determination unit similar to that of the first embodiment, and a detection signal is given from each of the rotation angle detection units 10U and 10D. In this case, the rotation angle is determined according to the flowchart shown in FIG. 4, and the determined rotation angle is output to the outside.
[0053]
Therefore, according to the rotation sensor of this modified example, even if two rotation angles can be obtained for one detection value given by one rotation angle detection means, the rotation angle is not given by the other rotation angle detection means. The rotation angle can be determined by specifying the detection phase of one of the rotation angle detecting means based on whether or not the detected signal exceeds the average level VM. In addition, since the detection signal given from either one of the rotation angle detection means always has a value in the high linearity range, it is possible to always expect high accuracy in the calculated rotation angle regardless of the detection range. . Therefore, for example, if the change in the relative rotation angle between the steering shaft and the vehicle body is input from the support shaft, the change in the relative rotation angle between the steering shaft and the vehicle body can be uniquely detected with high accuracy regardless of the detection range. Will be able to
[0054]
In this modification, the detailed configuration of the rotation angle detecting means is not limited to the above-described one. For example, the exciting coils 18U and 18D may be provided on the core 12, or the core 12 and the stators 13L and 13R may be connected to each other. The arrangement may be reversed. Further, the stators 13L and 13R may be connected to the support shaft 11 to form a rotor, while the rotor 14 may be fixed to form a stator.
[0055]
【The invention's effect】
As described above, according to the present invention, two rotation angle detection units are provided so as to output detection signals that are shifted from each other by 周期 period, and the detection signal obtained from one of the rotation angle detection units is set in advance. If it is within the range of the output level, the detection phase of one rotation angle detecting means is determined based on the output level of the detection signal acquired from the other rotation angle detecting means, and the determined detection phase and the one rotation Since the rotation angle is determined based on the detection signal obtained from the angle detection means, the change in the rotation angle can always be uniquely detected with high accuracy regardless of the detection range.
[Brief description of the drawings]
FIG. 1 is a conceptual diagram showing a rotation sensor according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view of the rotation sensor shown in FIG.
FIGS. 3 (a) and 3 (b) are graphs showing output results from the rotation sensor shown in FIG.
FIG. 4 is a flowchart illustrating a processing procedure of a rotation angle determining unit illustrated in FIG. 1;
5A and 5B show a modified example of the rotation sensor shown in FIG. 1, wherein FIG. 5A is a sectional side view, FIG. 5B is a sectional view taken along the line BB in FIG. 10 is a sectional view taken along line CC in FIG.
FIGS. 6A and 6B show a conventional rotation sensor.
FIG. 7 is a sectional view of the rotation sensor shown in FIG. 6;
FIG. 8 is a graph showing an output result of the rotation sensor shown in FIG.
[Explanation of symbols]
10L, 10R, 10U, 10D rotation angle detecting means
11L, 11R, 11 Support shaft
12L, 12R, 12 core
13L, 13R, 13U, 13D Stator
13aL, 13aR, 13aU, 13aD Coil core
14L, 14R, 14 rotor
14aL, 14aR, 14a Base
14bL, 14bR, 14b Rotor part
15L, 15R, 15U, 15D Reference plate
16L, 16R input gear
17L, 17R, 17U, 17D conductor
18L, 18R, 18U, 18D excitation coil
20 Rotation angle determination unit
115 housing
Area where the magnetic flux density is small
Fb High magnetic flux density area

Claims (4)

First rotation angle detection means for outputting a detection signal of a predetermined cycle according to a change in the rotation angle of the detection target;
A second rotation angle detection unit that outputs a detection signal having the same cycle as the first rotation angle detection unit and a phase shifted by 1/4 cycle in accordance with a change in the rotation angle of the detection target;
If the detection signal obtained from one of the rotation angle detection means is within a preset output level range, the detection of one of the rotation angle detection means is performed based on the output level of the detection signal obtained from the other rotation angle detection means. A rotation sensor comprising: a rotation angle determination unit that determines a phase and determines a rotation angle based on the determined detection phase and a detection signal obtained from the one rotation angle detection unit. The rotation angle detecting means,
A first rotation angle detection element formed of a magnetic material and forming a magnetic field having a non-uniform magnetic flux density along a circumferential direction between the core and the core when a current is applied to the excitation coil;
A second rotation angle detection element made of a conductive material, the second rotation angle detection element moving so as to change a ratio of an area crossing the non-uniform magnetic field when relatively rotated with respect to the first rotation angle detection element; The first rotation angle detection element and the second rotation angle detection element relatively rotate according to a change in the rotation angle of the detection target, and the excitation based on the relative rotation of the first and second rotation angle detection elements is performed. The rotation sensor according to claim 1, wherein a detection signal is output according to a change in impedance of the coil. 3. The rotation sensor according to claim 1, wherein the non-uniform magnetic field is formed by disposing a conductor on a part of the first rotation angle detection element along a circumferential direction. 4. A conductor is continuously arranged in a range of 180 ° of the first rotation angle detection element, and the second rotation angle detection element is formed in an arc shape having a size corresponding to the conductor. The rotation sensor according to claim 3.

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