JP2004170205A - Rotation angle detecting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To maintain a high detection precision of a multiple rotation type rotation angle detecting device over a long period of time. <P>SOLUTION: The rotation of a main gear 3 coaxial with a shaft 2 to be measured is transmitted to a reduction gear train 4. A quantity of rotation of the first gear 41 of the gear train 4 and a quantity of rotation of the third gear of the gear train 4 are detected, and an absolute rotation angle of the shaft 2 is calculated. The circular hub 32 of the first gear 41 is supported so as to be displaceable in an adjustment direction X, by a positioning unit 22 flatter a little than the circle of a positioning member 20 to be fixed to a first housing 11. An elastic member 34 elastically urges the first gear 41 via its hub 32 to the main gear 3 side, adjusts the distance D between the centers of the main gear 3 and the first gear 41, and removes the backlash between the main gear 3 and the first gear 41. <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]
[Prior 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, Patent Documents 1 and 2).
In the rotation angle detecting devices disclosed in Patent Documents 1 and 2, a pair of small diameter gears having different numbers of teeth are meshed with a large diameter gear surrounding a multi-rotation body, and a rotation angle corresponding to the rotation angle of each small diameter gear is detected. By detecting with the sensor, the absolute rotation angle is detected based on the phase difference between the small diameter gears.
[0003]
Further, there has been provided a rotation angle detection device that obtains an absolute rotation angle by combining detection angles of first and second sensors that accelerate the rotation angle of a multi-rotation body at first and second speed ratios (for example, provided). Patent Document 3).
[0004]
[Patent Document 1]
JP-A-11-500828 [Patent Document 2]
Japanese Patent Application Publication No. 2001-505667 [Patent Document 3]
JP 2000-9415 A
[Problems to be solved by the invention]
However, in the rotation angle detection devices of Patent Document 1 and Patent Document 2, the detection of the absolute rotation angle is based on the deviation of the rotation angle of the pair of small-diameter gears, each of which is accelerated with respect to the rotation angle of the multi-rotor, To increase the detection accuracy, the two rotation angle detection sensors are both required to have high accuracy.
In the rotation angle detection device of Patent Document 3, the detection of the absolute rotation angle is based on the detection angles of a pair of sensors that both accelerate the rotation angles of the multi-rotation body. Both require high precision.
[0006]
Further, in any of Patent Documents 1, 2, and 3, when the rotary sliding portion that rotatably supports the gears wears, the center-to-center distance between the gears fluctuates, the backlash increases, and the detection accuracy decreases. There is a problem.
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 capable of maintaining high detection accuracy for a long period of time.
[0007]
Means for Solving the Problems and Effects of the Invention
In order to achieve the above object, a first aspect of the present invention provides a main rotating body provided coaxially and integrally rotatable with a rotatable shaft to be measured, a first rotating body that is driven to rotate by gear transmission on the main rotating body, and A deceleration rotating body row including a final rotating body, a first rotation amount sensor for detecting the rotation amount of the first rotating body, a second rotation amount sensor for detecting the rotating amount of the final rotating body, Calculating means for detecting the absolute rotation angle of the shaft to be measured based on the amount of rotation detected by the first and second rotation amount sensors; A rotation angle detecting device is provided, comprising: a supporting means for supporting the first rotating body so as to be displaceable; and an elastic member for urging the first rotating body at least in a direction in which a center distance between the first rotating body and the main rotating body is reduced.
[0008]
In the present invention, when the shaft to be measured makes multiple rotations together with the main rotating body, the first rotating body and the last rotating body in the rotating body row are driven to rotate by gear transmission. At this time, based on the rotation of the first rotating body, the first rotation amount sensor for detecting one rotation outputs a detection signal that is highly accurate but is periodically repeated according to the rotation angle of the measured shaft. The second rotation amount sensor for multi-rotation detection detects the period of the detection signal of the first rotation amount sensor based on the rotation of the final rotating body, thereby obtaining the absolute value of the axis to be measured. The rotation angle can be accurately detected. Since the first rotation amount sensor for one rotation does not have to be disposed coaxially with the axis to be measured, the degree of freedom in layout is increased, and the versatility is excellent.
[0009]
In particular, a preload can be applied between the first rotating body and the main rotating body related to the first rotation amount sensor that requires high accuracy, and if the rotating sliding portions of these rotating bodies are worn, etc. However, the backlash of the gear transmission between these rotating bodies can be maintained at zero for a long time. As a result, high detection accuracy can be maintained for a long time.
In addition, as for the final rotating body, since the second rotation amount sensor related thereto is not required to have high accuracy, it is not necessary to particularly apply a preload, but the preload is also applied between the first rotating body and the final rotating body. May be added.
[0010]
According to a second aspect of the present invention, there is provided the rotation angle detecting device, further comprising a first unit and a second unit which can be attached to each other, wherein the first unit includes a main rotator and a second rotator which rotatably supports the main rotator. A first housing, wherein the second unit includes a rotator row, a second housing rotatably supporting the plurality of rotators of the rotator row, and attachable to the first housing; When the second housing is attached to the first housing, the urging force of the elastic member is applied to the main rotating body via the first rotating body, the second rotating amount sensor including the second rotation amount sensor, the supporting means, and the elastic member. Is provided.
[0011]
In the present invention, the preload can be automatically applied between the first rotating body and the main rotating body only by assembling the second unit to the first unit.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Preferred embodiments of the present invention will be described with reference to the accompanying drawings.
FIG. 1 is a schematic sectional view of a rotation angle detecting device according to an embodiment of the present invention. Referring to FIG. 1, the present rotation angle detecting device 1 includes a main gear 3 as a main rotating body which is concentrically disposed around a rotatable shaft 2 to be measured and rotates integrally with the shaft 2 to be measured. In order to detect the rotation amount of the first gear 41 and the gear train 4 as a rotating body row from a first gear 41 as a first rotating body to a third gear 43 as a final rotating body (final gear) meshing with the first gear 41. The first rotation amount sensor 5, the second rotation amount sensor 6 connected to the main gear 3 via the gear train 4, and the rotation amount detected by the first and second rotation amount sensors 5 and 6. An absolute angle calculation unit 7 (see FIG. 3) for calculating the absolute rotation angle of the measured shaft 2 based on the rotation angle is provided.
[0013]
Each of the gears 3, 41 to 43 is composed of a spur gear. The main gear 3 and the first gear 41 have, for example, the same diameter and a gear ratio of 1: 1. The diameter of the second gear 42 is set to, for example, １ ／ of the diameter of the third gear 43. Thereby, the rotation of the measured shaft 2 (main gear 3) can be reduced to, for example, 1/8.
However, the above reduction ratio can be freely set as long as multiple rotations can be detected, and the rotation angle of the measured shaft 2 may be reduced, for example, in the range of 1/4 to 1/10.
[0014]
Further, the first rotation amount sensor 5 is for detecting one rotation for detecting the rotation amount of the first gear 41, and the second rotation amount sensor 6 is for detecting the rotation amount of the third gear 43 as the final gear. For detecting multiple rotations.
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.
[0015]
The rotation angle detection device 1 includes first and second units 8 and 9 that can be attached to each other. The first unit 8 includes the main gear 3 and a first housing 10 that rotatably supports the main gear 3. The second unit 9 includes the gear train 4 and a second housing 11 that rotatably supports the gears 41, 42, and 43 of the gear train 4 and that can be attached to the first housing 10 by, for example, screws. Including.
[0016]
Referring to FIG. 2 and FIG. 1 which are cross-sectional views taken along line II-II of FIG. 1, the gear train 4 includes a first shaft 12 as an intermediate shaft and a second shaft 13 as a final shaft. Prepare. The first and second axes 12 and 13 are parallel to the axis 2 to be measured.
As shown in FIG. 1, the second housing 11 is provided with an opening 15 on a surface 14 on the side of attachment to the first housing 10, and as shown in FIG. , 9 are assembled so that the main gear 3 and the first gear 41 mesh with each other through the opening 15.
[0017]
With reference to FIGS. 1 and 2, the housing 16 is a housing formed in the second housing 11 and houses the gear train 4 and the like.
Referring to FIG. 2, the second housing 11 of the second unit 9 is formed by combining an upper housing 17 and a lower housing 18 in a mode in which the above-described housing portion 16 for the gear train 4 is provided inside. The upper and lower housings 17, 18 are sandwiched between a boss 17a having screw holes provided at, for example, four corners of the upper housing 17 and a corresponding portion 18a of the lower housing 18, with the circuit board 19 and the positioning member 20 being sandwiched therebetween. Are fastened using, for example, four fixing screws 21.
[0018]
Referring to FIGS. 3 and 4 which are cross-sectional views taken along the line III-III in FIG. 2, positioning member 20 includes a positioning member formed of a cylindrical projection for positioning first gear 41 and third gear 43. Parts 22, 23 (supporting means), a connecting part 24 connecting the positioning parts 22, 23 to each other, a pair of support arms 25, 26 extending radially from the positioning part 22, and a pair of supporting arms radially extending from the positioning part 23. Support arms 27 and 28. Bosses 29 are formed at the distal ends of the support arms 25 to 28 so that the corresponding fixing screws 21 are inserted therethrough. Actually, as shown in FIG. 2, the collar 30 is inserted into the boss 29 and the insertion hole of the circuit board 19, and the fixing screw 21 is inserted into the collar 30.
[0019]
As shown in FIGS. 3 and 4, the positioning portion 22 has a substantially circular shape, but is slightly flattened in an adjustment direction X described later.
Referring again to FIG. 2, on the same axis of the first shaft 12, the first gear 41 meshing with the main gear 3 and the second gear 42 having a smaller diameter and integrally rotating with the first gear 41 are provided. Can be Specifically, the first shaft 12 protrudes from the first surface 41 a of the first gear 41, and a second gear 42 is formed around an intermediate portion of the first shaft 12 in the axial direction. The tip 12 a of the shaft 12 is rotatably supported by a support hole 31 of the upper housing 17.
[0020]
On the other hand, a hub 32 formed of a circular annular projection concentric with the first shaft 12 is formed on the second surface 41 b of the first gear 41. The hub 32 is rotatably fitted to the corresponding positioning portion 22 of the positioning member 20. The first and second gears 41 and 42, the hub 32, and the first shaft 12 are formed of, for example, an integral synthetic resin molded product, thereby reducing costs.
Referring to FIG. 3, positioning portion 22 has a substantially circular shape, but is slightly flattened in a direction (corresponding to adjustment direction X) connecting center C1 of main gear 3 and center C2 of first gear 41. Thereby, a predetermined amount of movement of the hub 32 with respect to the positioning portion 22 is allowed. That is, a gap S is provided between the hub 32 and the positioning portion 22 in the adjustment direction X, and the first gear 41 moves closer to the center distance D with the main gear 3 (that is, the distance between the center C1 and the center C2). It can be displaced in the direction.
[0021]
Further, an elastic member 34 for urging the first gear 41 toward the main gear 3 via the hub 32 is interposed between the receiving portion 33 provided on the lower housing 18 and the hub 32. As the elastic member 34, a U-shaped leaf spring that slides the pair of spring pieces 35, 35 on the peripheral surface of the hub 32 can be used. The central portion of the square of the elastic member 34 (the connecting portion between the pair of spring pieces 35, 35) is received by the receiving portion 33. The elastic member 34 elastically urges the first gear 41 displaceable in the adjustment direction X toward the main gear 3 via the hub 32 as described above, and adjusts the center-to-center distance D so that the main gear 3 and the It functions to remove backlash between the first gear 41.
[0022]
Referring to FIG. 2, on the same axis as second shaft 13 as the last shaft, there is provided a third gear 43 as the last gear, which has a larger diameter than second gear 42 and meshes with second gear 42. One end 13a of the second shaft 13 projects from the first surface 43a of the third gear 43, and is rotatably supported by a corresponding support hole 36 of the upper housing 17.
The other end 13b of the second shaft 13 has a larger diameter than the one end 13a and protrudes from the second surface 43b of the third gear 43. At the other end 13b, a hub 37 formed of a circular annular projection concentric with the center C3 of the third gear 43 is formed. The hub 37 is rotatably fitted in the positioning portion 23 of the positioning member 20 formed of a circular annular projection. The third gear 43, the second shaft 13, and the hub 37 are formed of, for example, an integral synthetic resin molded product, and cost reduction is achieved.
[0023]
The end surface of the positioning portion 22 of the positioning member 20 receives the second surface 41b of the first gear 41, and the end surface of the positioning portion 23 receives the annular step portion 38 at the base end of the hub 37. 22 and 23 also function as thrust bearings for receiving the first and third gears 41 and 43 in the axial direction, respectively.
The first rotation amount sensor 5 has a movable portion 5a and a fixed portion 5b facing each other. The movable portion 5a is fixed to the second surface 41b of the first gear 41 coaxially with the first gear 41, and rotates integrally with the first gear 41. The fixing portion 5b is fixed to a circuit board 19 as a fixing member.
[0024]
Similarly, the second rotation amount sensor 6 has a movable portion 6a and a fixed portion 6b facing each other. The movable portion 6a is coaxial with the third gear 43 serving as the final gear, and is provided with, for example, a concave portion 39 of the second surface 43b of the third gear 43 (the concave portion 39 is the other end 13b of the second shaft 13 as shown in FIG. (Which may be formed on the end surface of the third gear 43). The fixing portion 6b is fixed to the circuit board 19. The above-described absolute angle calculation unit 7 is mounted on the circuit board 19.
[0025]
It is possible to use, for example, an annular plate-shaped sintered permanent magnet as the movable parts 5a, 6a of the rotation amount sensors 5, 6, and to use, for example, a magnetic sensor as the fixed parts 5b, 6b.
The movable portion 6a made of a permanent magnet may be fixed to the concave portion 39 of the third gear 43 made of a resin molded body, for example, by press fitting or bonding. The movable part 6a slips or falls off the concave portion 39 when the temperature changes due to a problem that the positioning accuracy of the movable part 6a cannot be made very high or a difference in temperature expansion between the movable part 6a and the third gear 43. There is a concern that this problem will occur.
[0026]
Therefore, as shown in FIG. 6A, one or a plurality of rotation regulating and retaining stopper projections 50 are provided on the peripheral surface of the movable portion 6a formed of an annular plate, and the inside of the molding die of the third gear 43 is formed. Preferably, the movable portion 6a is inserted into the third gear 43, and the protrusion 50 is embedded in the third gear 43 as shown in FIG.
In this case, a unit in which the movable portion 6a is fixed to the third gear 43 at the same time as the resin molding of the third gear 43 is obtained by insert molding, and the number of steps can be reduced. In addition, since the positioning pin of the molding die can be inserted into the center hole 51 of the movable portion 6a during resin molding, the positioning accuracy of the movable portion 6a with respect to the third gear 43 can be increased. Further, since the projection 50 is fitted into the third gear 43, it is possible to prevent the movable portion 6a from slipping or slipping out. Further, the projection 50 can be formed with high precision at the same time when the movable portion 6a is formed by the sintering die, and it does not require much labor.
[0027]
Referring to FIG. 7, detection signals from first rotation amount sensor 5 and second rotation amount sensor 6 are input to absolute angle calculation unit 7 as calculation means. The absolute rotation angle of the measured shaft 2 is calculated based on the rotation amounts of the first gear 41 and the third gear 43 detected by the second rotation amount sensors 5 and 6.
Next, FIG. 8 is a graph showing the relationship between the rotation angle of the measured shaft 2 and the output waveforms of the rotation amount sensors 5 and 6. When the gear ratio between the main gear 3 and the fourth gear 41 is, for example, 1: 1, the rotation of the measured shaft 2 is transmitted to the first gear 41 at a constant speed. When, for example, the steering shaft as the measured shaft 2 is rotated four times, as shown in FIG. 8, the output S1 of the first rotation amount sensor 5 for detecting the rotation amount of the first gear 41 (in FIG. Is a sawtooth waveform having a period of, for example, 360 deg. Although the output S1 of the first rotation amount sensor 5 has high detection accuracy, the output S1 is repeated four times in a 360 deg cycle, so it is not known which cycle the output S1 is.
[0028]
On the other hand, the rotation of the third gear 43 as the final gear is reduced to, for example, ８ times the rotation of the main gear 3, and the output of the second rotation amount sensor 6 for detecting the rotation amount of the third gear 43. S2 (indicated by a broken line in FIG. 8) has a waveform that rises substantially linearly up to, for example, 1440 deg. Based on the level of the output S2 of the second rotation amount sensor 6, it is possible to determine in which cycle the output value of the first rotation amount sensor 5 is a value. Therefore, the absolute rotation angle of the measured shaft 2 can be detected with high accuracy.
[0029]
In particular, as shown in FIG. 3, since a preload can be applied by the elastic member 34 between the first gear 41 and the main gear 3 related to the first rotation amount sensor 5 that requires high accuracy, the main gear 3 and the Even if the rotational sliding portion of the first gear 41 wears or the like, the backlash of the gear transmission between the main gear 3 and the first gear 41 can be maintained at zero for a long time. As a result, high detection accuracy can be maintained for a long time.
[0030]
As shown in FIG. 3, as the elastic member 34, a pair of spring pieces 35 of a U-shaped leaf spring are brought into sliding contact along the tangential direction of the peripheral surface of the hub 32. Is preferable because the rotation resistance can be reduced.
Further, as shown in FIG. 5, simply by assembling the second unit 9 to the first unit 8, a preload can be automatically applied between the main gear 3 and the first gear 41, and the assembly is easy.
[0031]
Further, the first and second gears 41 and 42 are provided as two-stage gears on the first shaft 12, and the large-diameter third gear 43 meshes with the small-diameter second gear 42, as shown in FIG. When viewed from the axial direction, the third gear 43 can be laid out such that a part of the third gear 43 overlaps a part of the first gear 41, and the size can be reduced.
In addition, the fixing portions 5b and 6b of the first and second rotation amount sensors 5 and 6 can be mounted on a common substrate, and cost can be reduced.
[0032]
The present invention is not limited to the above-described embodiment. For example, as for the third gear 43 as the final rotating body, the second rotation amount sensor 6 related to the third gear 43 does not need to have so high accuracy. It is not particularly necessary to apply a preload, but a preload may be applied between the first gear 41 and the third gear 43. For example, as shown in FIG. 9, the gap S <b> 1 between the positioning portion 22 and the hub 32 is not only the increase or decrease of the center distance D between the main gear 3 and the first gear 41, but also the first gear 41 and the third gear 41. The center-to-center distance d from the center 43 (the distance between the center C1 and the center C3) is allowed to increase or decrease. For example, the adjustment is performed so that the U-shaped elastic member 34 can be urged in both the adjustment directions X and Y. The urging force F works obliquely with respect to the directions X and Y.
[0033]
A known resolver can be used as the first rotation amount sensor, and various modifications can be made within the scope of the claims of the present invention, such as using a compression coil spring as the elastic member.
[Brief description of the drawings]
FIG. 1 is a schematic sectional view showing a schematic configuration of a rotation angle detecting device according to an embodiment of the present invention.
FIG. 2 is a sectional view taken along the line II-II in FIG.
FIG. 3 is a sectional view taken along line III-III in FIG. 2;
FIG. 4 is a schematic plan view of a positioning member.
FIG. 5 is a partially exploded view showing one process when assembling the rotation angle detecting device into a unit.
6A is a plan view of a movable portion of a second rotation amount sensor, and FIG. 6B is a cross-sectional view of a main part of a third gear in which the movable portion is insert-molded.
FIG. 7 is a block diagram showing a main part of an electrical configuration of the rotation angle detection device.
FIG. 8 is a graph showing the relationship between the rotation angle of the measured shaft and the output of each rotation angle detection sensor.
FIG. 9 is a schematic diagram of a rotation angle detection device according to another embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Rotation angle detection device 2 Measured shaft 3 Main gear (main rotating body)
4 Gear train (rotating body row)
5 First rotation amount sensor 6 Second rotation amount sensor 5a, 6a Movable section 5b, 6b Fixed section 7 Absolute angle calculation section (calculation means)
8 First unit 9 Second unit 10 First housing 11 Second housing 12 First shaft 13 Second shaft (final shaft)
15 Opening part 17 Upper housing 18 Lower housing 19 Circuit board 20 Positioning members 22, 23 Positioning part (supporting means)
32 hub 33 receiving part 34 elastic member 35 spring piece 37 hub 41 first gear (first rotating body)
42 2nd gear 43 3rd gear (final rotating body)
50 Projection C1, C2, C3 Center D, d Distance between centers X, Y Adjustment direction

Claims (2)

A main rotating body provided coaxially and rotatable with a rotatable shaft to be measured,
A row of decelerating rotators including a first rotator and a final rotator that are driven to rotate by gear transmission on the main rotator;
A first rotation amount sensor for detecting a rotation amount of the first rotating body;
A second rotation amount sensor for detecting the rotation amount of the final rotating body;
Calculating means for detecting the absolute rotation angle of the measured shaft based on the rotation amounts detected by the first and second rotation amount sensors;
Support means for supporting the first rotating body so that it can be displaced in a direction in which at least the center-to-center distance with the main rotating body is far away;
An elastic member for urging the first rotating body at least in a direction in which a center distance between the first rotating body and the main rotating body is reduced. In claim 1,
A first unit and a second unit attachable to each other,
The first unit includes a main rotating body and a first housing rotatably supporting the main rotating body,
The second unit includes a rotating body row, a second housing rotatably supporting the plurality of rotating bodies in the rotating body row and attachable to the first housing, and the first and second rotation amount sensors. And, including the supporting means, and the elastic member,
A rotation angle detecting device, wherein when the second housing is attached to the first housing, the urging force of the elastic member is applied to the main rotating body via the first rotating body.

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