JP2004061373A - Rotation angle detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rotation angle detector of multi-rotation type having high detection accuracy. <P>SOLUTION: A second gear 4 comprising a spur gear meshes in the gear ratio of 1 to 1 with a first gear 3 comprising a shaft to be measured 2 and a spur gear coaxial therewith. A vortical guide track 5 centering around a rotation axis line 4c is formed on a first end face 4a of the second gear 4. A swing arm 6 is provided turnable around a prescribed axis line 7 serving as a fulcrum. When the shaft to be measured 2 rotates, a second end part 6b of the swing arm 6 traces the guide track 5 to cause the swing arm 6 to make turning motion around the prescribed axis line 7. When the shaft 2 makes multiple rotation, rotation angle output of the second gear 4 detected by a second rotation angle detection sensor 12 is given a repetitive wave form of a fixed period with respect to the rotation angle of the second gear 4. Rotation angle output of the swing arm detected by a first rotation angle detection sensor 11 is used to determine, to which period the output value of the second sensor 12 corresponds. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a rotation angle detection device that detects an absolute rotation angle of a multi-rotation shaft.
[0002]
2. Description of the Related Art
Usually, the measurement range of the rotation angle detection sensor is within one rotation (360 °). A rotation angle detection device that detects the absolute rotation angle of a multi-rotation type rotation shaft using such a rotation angle detection sensor has been provided (for example, JP-A-10-30909 and JP-A-2974717). reference).
In the former rotation angle detecting device disclosed in Japanese Patent Application Laid-Open No. 10-30909, a single rotation angle detection sensor is used to detect the absolute rotation angle of a multi-rotation type rotation shaft. Therefore, multiple rotations (for example, four rotations) of the rotating shaft are decelerated within the measurement range of the rotation angle detection sensor (within one rotation), and the rotation reduced by the deceleration is detected by the rotation angle detection sensor. For this reason, the resolution decreases and the detection accuracy deteriorates.
[0003]
In the latter rotation angle detecting device of Japanese Patent No. 2974717, a first rotation angle detection sensor outputs a fine signal that is repeated every rotation of the rotation shaft, and the second rotation angle detection sensor rotates the rotation shaft. And outputs the coarse signal detected over the entire range, and detects the absolute rotation angle of the rotary shaft based on the fine signal and the coarse signal.
In this rotation angle detection device, an annular detection member is provided coaxially with the rotation axis, and a spiral guide track is provided on the annular detection member. The second rotation angle detection sensor comprises a linear sliding potentiometer, and linearly tracks the spiral guide trajectory to output a coarse signal.
[0004]
However, in this rotation angle detection device, there is a problem that the output of the second rotation angle detection sensor is not proportional to the rotation angle of the rotation shaft (that is, the detection member), and linear detection characteristics cannot be obtained.
The present invention has been made in view of the above problems, and has as its object to provide a multi-rotation type rotation angle detection device with high detection accuracy.
[0005]
Means for Solving the Problems and Effects of the Invention
To achieve the above object, the invention according to claim 1 includes a first gear disposed coaxially with a rotatable shaft to be measured, a second gear meshing with the first gear, and a second gear. A spiral guide track provided on the end face of the gear, and first and second ends. The first end is swingably supported around a predetermined fulcrum, and A swing arm whose end is guided by the spiral guide track, first rotation angle detection means for detecting the rotation angle of the swing arm, and detection of the rotation angle of the second gear And a calculating means for calculating the absolute rotation angle of the shaft to be measured based on the rotation angles detected by the first and second rotation angle detecting means. Provided is a rotation angle detection device.
[0006]
In the present invention, when the measured shaft makes multiple rotations, the second rotation angle detecting means outputs a detection signal which is highly accurate but is periodically repeated according to the rotation angle of the measured shaft. In which period the detection signal of the second rotation angle detection means is a detection signal is detected based on the rotation angle of the swing arm by the first rotation angle detection means, and the absolute rotation of the measured shaft is determined. The angle can be detected with high accuracy.
If a spiral guide path is provided on an annular member disposed coaxially with the measured axis around the measured axis, the rotation angle range of the swing arm is narrowed. However, in the present invention, the second gear is meshed with the first gear coaxial with the axis to be measured, and a spiral guide track is provided on the end face of the second gear. The rotation angle range of the swing arm can be widened, and the detection accuracy of the rotation angle of the swing arm can be increased.
[0007]
According to a second aspect of the present invention, in the first aspect, the predetermined fulcrum is arranged at a position facing an end face of the second gear. According to the present invention, since the span of the swing arm can be shortened, the rotation angle of the swing arm with respect to the rotation angle of the shaft to be measured can be increased. As a result, the detection accuracy of the first rotation angle detecting means can be increased.
According to a third aspect of the present invention, in the first aspect, the predetermined fulcrum comprises a movable fulcrum rotatable around a predetermined central axis. In the present invention, since the rotation angle of the swing arm changes substantially linearly with respect to the rotation angle of the shaft to be measured, the calculation processing by the calculation means is simplified.
[0008]
According to a fourth aspect of the present invention, in the third aspect, a guide member facing the end face of the second gear is provided, and the guide member has a curved shape for guiding the second end of the swing arm. In which the guide track is provided. In the present invention, it is possible to further improve the detection accuracy by obtaining a linear detection characteristic.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Preferred embodiments of the present invention will be described with reference to the accompanying drawings.
1 and 2 are a schematic plan view and a schematic cross-sectional view of a rotation angle detection device according to one embodiment of the present invention. Referring to FIG. 1, the present rotation angle detection device 1 includes a first gear 3 that is coaxially disposed around a rotatable shaft 2 to be measured and rotates integrally with the shaft 2 to be measured, and a first gear 3 And a second gear 4 meshing with the third gear 3. The first and second gears 3, 4 are spur gears. The first and second gears 3 and 4 have, for example, the same diameter and a gear ratio of 1: 1.
[0010]
In the present embodiment, a description will be given of a case where the rotation angle detection device 1 is applied to an electric power steering device to detect the rotation angle of a steering member (not shown) such as a steering wheel. In this case, the measured shaft 2 is constituted by a shaft that rotates integrally with the steering member. However, the present invention can be applied to general absolute angle detection of multiple rotation axes.
Referring to FIGS. 1 and 2, the second gear 4 has a first end face 4a and a second end face 4b, and the first end face 4a has a rotation axis 4c of the second gear 4 as a center. A spiral guide track 5 is formed. The spiral guide track 5 may be formed of a groove or a ridge.
[0011]
The guide track 5 guides the swing of the swing arm 6. The swing arm 6 has first and second ends 6a and 6b, and the first end 6a is swingably supported around a predetermined axis 7 as a predetermined fulcrum. You. The tracer 6c provided at the second end 6b is engaged with the spiral guide track 5, and is guided by the guide track 5 when the swing arm 6 swings.
As shown in FIG. 2, when the spiral guide track 5 has, for example, a semicircular cross section, the tracer 6c at the second end 6b may be spherical. The spherical body may be supported at the second end 6b so that it can roll, for example, a groove as the guide track 5.
[0012]
The predetermined axis 7 is the center axis of a support shaft 8 as a fulcrum forming means. The support shaft 8 is rotatably supported around the predetermined axis 7 by a fixing member 9 such as a sensor housing fixed to the steering column, for example. On the same axis as the support shaft 8, a rotating body 10 made of, for example, a disk and rotating integrally with the support shaft 8 is provided, and the swing arm 6, the support shaft 8 and the rotating body 10 rotate integrally.
A first rotation angle detection sensor 11 for detecting the rotation angle (swing angle) of the swing arm 6 is provided coaxially with the rotating body 10. The first rotation angle detection sensor 11 has a movable part 11a and a fixed part 11b. The movable portion 11a is fixed to a second end surface 10b, which is a surface opposite to the first end surface 10a on which the support shaft 8 of the rotating body 10 is provided, and rotates integrally with the rotating body 10. The fixing portion 11b is fixed to a fixing member (not shown) such as a substrate.
[0013]
On the other hand, a second rotation angle detection sensor 12 for detecting the rotation angle of the second gear 4 is provided coaxially with the rotation axis 4c of the second gear 4. The second rotation angle detection sensor 12 has a movable part 12a and a fixed part 12b. The movable portion 12a is fixed to a second end surface 4b which is a surface opposite to the first end surface 4a on which the guide track 5 of the second gear 4 is provided, and rotates integrally with the second gear 4. The fixing portion 12b is fixed to a fixing member (not shown) such as a substrate.
[0014]
Detection signals from the first rotation angle detection sensor 11 and the second rotation angle detection sensor 12 are input to an absolute angle calculation unit 13 as calculation means, and the absolute angle calculation unit 13 outputs the first and second rotation angles. The absolute rotation angle of the measured shaft 2 is calculated based on the rotation angles of the swing arm 6 and the second gear 4 detected by the detection sensors 11 and 12.
Next, FIG. 3 is a graph showing the relationship between the rotation angle of the measured shaft 2 and the output waveforms of the rotation angle detection sensors 11 and 12. When, for example, the steering shaft as the measured shaft 2 is rotated four times, as shown in FIG. 3, the output S2 of the second rotation angle detection sensor 12 that detects the rotation angle of the second gear 4 (in FIG. 3, (Indicated by a solid line) is a saw-tooth waveform having a period of, for example, 180 deg. Although the output S2 of the second rotation angle detection sensor 12 has high detection accuracy, the output S2 is repeated eight times in a 180 deg cycle, so it is not known which cycle it is.
[0015]
On the other hand, the output S1 of the first rotation angle detection sensor 11 that detects the rotation angle of the swing arm 6 has a waveform that rises substantially linearly up to, for example, 1440 deg. Based on the level of the output S1 of the first rotation angle detection sensor 11, it is possible to determine in which cycle the output value of the second rotation angle detection sensor 11 is a value. Therefore, the absolute rotation angle of the measured shaft 2 can be detected with high accuracy.
Further, the second gear 4 is meshed with the first gear 3 coaxial with the shaft 2 to be measured, and the spiral guide track 5 is provided on the end face 4a of the second gear 4. There is also an advantage that the rotation angle range of the swing arm 6 can be widened and the detection accuracy of the rotation angle of the swing arm 6 can be increased.
[0016]
4 and 5 show another embodiment of the present invention. Referring to FIGS. 4 and 5, rotation angle detecting device 1A of the present embodiment is mainly different from rotation angle detecting device 1 of the embodiment of FIGS. 1 and 2 in that swing arm 6 swings. The point is that a predetermined axis 7 as a predetermined fulcrum is laid out at a position facing the end face 4 a of the second gear 4.
Specifically, an extension arm 14 fixed to a fixing member 9 such as a sensor housing fixed to the steering column and extending parallel to the end face 4a of the second gear 4 is provided. The swing arm 6 is supported via the shaft 8.
[0017]
In the present embodiment, the first rotation angle detection sensor 15 for detecting the rotation angle of the swing arm 6 is arranged on the side opposite to the second rotation angle detection sensor 12. The first rotation angle detection sensor 15 includes a movable portion 15a that rotates integrally with the support shaft 8, and a fixed portion 15b that is fixed to a fixed member such as a substrate. In the present embodiment, the same components as those in the embodiment of FIG. 2 are denoted by the same reference numerals in the drawings, and description thereof will be omitted.
According to the present embodiment, as shown in FIG. 4, the span of the swing arm 6 can be shortened, so that the rotation angle of the swing arm 6 with respect to the rotation angle of the measured shaft 2 can be increased, and as a result, the first rotation angle The detection accuracy of the detection sensor 15 can be increased.
[0018]
6 and 7 show still another embodiment of the present invention. Referring to FIGS. 6 and 7, the main difference between the present embodiment and the embodiment shown in FIGS. 1 and 2 is that in the embodiment shown in FIGS. Although the predetermined axis 7 is made to coincide with the rotation axis of the rotating body 10, in the present embodiment, the predetermined axis 7 a serving as a fulcrum of the swing of the swing arm 6 is shifted from the rotation axis 16 of the It is offset by a predetermined offset amount D. Therefore, the predetermined axis 7 a as a fulcrum becomes a movable fulcrum that moves along an arc-shaped trajectory 17 centered on the rotation axis 16.
[0019]
The support shaft 8 of the first end 6a of the swing arm 6 is rotatably supported by the receiving portion 18 fixed to the first end face 10a of the rotating body 10. An extension shaft 6d extending parallel to a predetermined axis 7a extends from the second end 6b of the swing arm 6, and a tracer 6c is provided at the tip of the extension shaft 6d. .
The extension shaft 6d passes through a guide groove 20 as a guide track formed on a guide member 19 parallel to the first end face 4a of the second gear 4. The guide member 19 is fixed to a fixing member such as a sensor housing fixed to the steering column. Referring to FIG. 8, the guide groove 20 has a curved shape, and guides the displacement of the second end 6b of the swing arm 6 via the extension shaft 6d.
[0020]
According to the present embodiment, by setting the shape of the guide groove 20, it is possible to obtain a linear detection characteristic of the first rotation angle detection sensor 11 with respect to the rotation of the measured shaft 2, and as a result, the detection accuracy Can be further improved. Further, since a linear detection characteristic is obtained, the processing of the detection signal is also simplified.
Next, FIG. 9 is a schematic sectional view showing an example of a case where the rotation angle detecting device 1B of the embodiment shown in FIGS. 6 to 8 is schematically packaged, and FIG. It is a top view of the positioning member used.
[0021]
Referring to FIG. 9, a support shaft 21 protruding along a rotation axis 4c of the second gear 4 is provided on the first end surface 4a of the second gear 4 so as to be integrally rotatable. On the other hand, on the second end face 4b of the second gear 4, an annular projection 22 centering on the rotation axis 4c is formed.
A support shaft 23 that protrudes along the rotation axis 16 of the rotating body 10 is provided on the first end face 10 a of the rotating body 10 so as to be integrally rotatable. On the other hand, on the second end face 10 b of the rotating body 10, an annular projection 24 centering on the rotation axis 16 is formed.
[0022]
In a state where the substrate 27 and the positioning member 28 are sandwiched between the first case 25 and the second case 26, the first and second cases 25 and 26 Be concluded. The screw 40 passes through the first case 25, the positioning member 28, and the substrate 27 in order, and is screwed into the screw hole 41 of the second case 26. The above-mentioned substrate 27 mounts the fixing portions 11b and 12b of the rotation angle detecting means 11 and 12, respectively. Reference numeral 42 denotes a circuit element group mounted on the substrate 27.
[0023]
The support shaft 21 of the second gear 4 and the support shaft 23 of the rotating body 10 are fitted into support holes 29 and 30 formed in the first case 25, respectively, and are rotatably supported. On the other hand, the second gear 4 and the annular projections 22 and 24 of the rotating body 10 are rotatably fitted to positioning portions 31 and 32 formed on the positioning member 28 and formed of, for example, a cylinder. This fit may be loose.
In addition, the second gear 4 is received in the axial direction by receiving the second end face 4 b of the second gear 4 by the end face of the positioning part 31, and the rotating body 10 is received by the end face of the positioning part 32. By receiving the second end face 10b, the rotating body 10 is received in the axial direction. The positioning portions 31 and 32 function as thrust bearings of the second gear 4 and the rotating body 10, respectively.
[0024]
9 and 10, positioning member 28 is formed of, for example, an integrally molded product of synthetic resin. The positioning member 28 includes a connecting portion 33 for connecting the positioning portions 31 and 32 to each other, a pair of support arms 34 and 35 extending radially from the positioning portion 31, and a pair of support arms 36 and 37 extending radially from the positioning portion 32. And Bosses 39 each having a screw insertion hole 38 through which a fixing screw 40 of the first and second cases 25 and 26 is inserted are formed at the distal end of each of the support arms 34 to 37. That is, the positioning member 28 is fixed together with the substrate 27 to the first and second cases 25 and 26 by joint fastening.
[0025]
According to the present embodiment, the inclination of second gear 4 and rotating body 10 is suppressed by supporting both second gear 4 and rotating body 10 associated with each other via swing arm 6. As a result, it is possible to prevent variations in detection accuracy.
In particular, since the second gear 4 and the support shafts 21 and 23 of the rotating body 10 are positioned relative to each other only through the first case 25 which is a single member, the positioning accuracy between the support shaft 21 and the support shaft 23 is determined. Is high.
[0026]
Similarly, since the second gear 4 and the annular projections 22 and 24 of the rotating body 10 are positioned with respect to each other only through the positioning member 28 which is a single member, the positioning accuracy between the annular projection 22 and the annular projection 24 is improved. high.
In addition, since the positioning member 28 is an integrally molded product of synthetic resin, it can be manufactured at low cost.
Note that the present invention is not limited to the above embodiments, and various changes can be made within the scope of the claims of the present invention.
[Brief description of the drawings]
FIG. 1 is a schematic plan view showing a schematic configuration of a rotation angle detection device according to an embodiment of the present invention.
FIG. 2 is a partially cutaway schematic side view of the rotation angle detection device of FIG.
FIG. 3 is a graph showing a relationship between a rotation angle of a measured shaft and an output of each rotation angle detection sensor in the embodiment of FIG. 1;
FIG. 4 is a schematic plan view illustrating a schematic configuration of a rotation angle detection device according to another embodiment of the present invention.
5 is a schematic side view, partially broken away, of the rotation angle detecting device of FIG. 4;
FIG. 6 is a schematic plan view showing a schematic configuration of a rotation angle detection device according to still another embodiment of the present invention.
7 is a schematic side view, partially broken away, of the rotation angle detection device of FIG. 6;
FIG. 8 is a plan view of the guide member in which the extension shaft is inserted in the embodiment of FIG. 6;
9 is a schematic cross-sectional view of the rotation angle detection device, showing an example of a case where the rotation angle detection device according to the embodiment of FIGS. 6 to 8 is actually packaged.
FIG. 10 is a plan view of a positioning member used in the embodiment of FIG.
[Explanation of symbols]
1, 1A, 1B Rotation angle detecting device 2 Measured shaft 3 First gear 4 Second gear 4a First end face 4b Second end face 4c Rotation axis 5 Spiral guide track 6 Swing arm 6a First End 6b Second end 6c Tracer 7 Predetermined axis (predetermined fulcrum)
7a Predetermined axis (movable fulcrum)
8 Support shaft 9 Fixed member 10 Rotary body 11 First rotation angle detection sensor 12 Second rotation angle detection sensor 13 Absolute angle calculation unit (calculation means)
14 Extension arm 15 First rotation angle detection sensor 16 Rotation axis 17 Locus 18 Receiving part 19 Guide member 20 Guide groove (curved guide track)
28 Positioning members 31, 32 Positioning part

Claims (4)

A first gear disposed coaxially with the rotatable shaft to be measured;
A second gear meshing with the first gear;
A spiral guide track provided on an end face of the second gear;
A swinging guide having a first end and a second end, wherein the first end is swingably supported around a predetermined fulcrum, and the second end is guided by the spiral guide track. A moving arm,
First rotation angle detection means for detecting the rotation angle of the swing arm;
Second rotation angle detection means for detecting the rotation angle of the second gear;
A rotation angle detection device comprising: a calculation unit configured to calculate an absolute rotation angle of the measured shaft based on the rotation angles detected by the first and second rotation angle detection units. 2. The rotation angle detecting device according to claim 1, wherein the predetermined fulcrum is arranged at a position facing an end face of the second gear. 2. The rotation angle detecting device according to claim 1, wherein the predetermined fulcrum comprises a movable fulcrum rotatable around a predetermined central axis. 4. The device according to claim 3, further comprising a guide member facing an end surface of the second gear, wherein the guide member has a curved guide track for guiding the second end of the swing arm. Rotation angle detecting device.

Images