Rotation angle detection device

Abstract

The rotation angle detection device of the present invention can reduce costs and achieve thinning. The rotation angle detection device includes: a housing; a rotation shaft rotatably disposed on the housing; a rotating body configured to rotate integrally with the rotation shaft; a first internal gear concentrically disposed with the rotation shaft and fixed to the housing; a second internal gear concentrically disposed with the rotation shaft, having a number of teeth different from that of the first internal gear, and rotatably disposed on the housing; an external gear rotatably disposed at a position spaced apart from the rotation shaft in the rotating body and meshing with the first internal gear and the second internal gear; and a detection unit that detects the rotation angle of the second internal gear.

Description

Technical Field

[0001] The present invention relates to a rotational angle detection device. Background Art

[0002] As an existing rotational angle detection device, a potentiometer is known, for example, which detects the rotational angle of a rotating member included in office automation equipment, industrial machinery, etc., or the amount of a wire fed out from a reel as a movement amount. In addition, among such rotational angle detection devices, some devices detect multi-turn rotation (for example, rotation dozens of turns) of a rotating member and a reel. For example, in order to detect multi-turn rotation of a rotating member or the like, a reduction mechanism capable of obtaining a large reduction ratio is required.

[0003] For example, Patent Document 1 discloses a potentiometer including a shaft and a reduction mechanism that converts the rotational angle of a reduced spur gear into voltage. The reduction mechanism includes four spur gears and reduces the rotation of the shaft.

[0004] In addition, for example, Patent Document 2 discloses such a potentiometer that includes a screw, a worm gear that rotates integrally with the screw, a gear that meshes with the worm gear, and an indicator that rotates together with the gear.

[0005] Prior Art Documents

[0006] Patent Documents

[0007] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2014-167427

[0008] Patent Document 2: Japanese Utility Model Registration No. 57-037205 Summary of the Invention

[0009] Problems to be Solved by the Invention

[0010] However, in the potentiometer described in Patent Document 1, in order to obtain a large reduction ratio, small-diameter gears are required. In addition, it is necessary to improve the dimensional accuracy and assembly accuracy of the gears and the bearing portions of the gears. As a result, there is a problem of cost increase. In addition, in the case where gears are arranged in multiple stages in order to obtain a large reduction ratio, for example, it is necessary to increase the length in the rotational axis direction (depth direction) of the gears, so there is a problem that it is difficult to make the device thin.

[0011] In addition, in the potentiometer described in Patent Document 2, it is necessary to improve the dimensional accuracy and assembly accuracy of the worm gear and the gear. As a result, there is a problem of cost increase. In addition, since the rotational axis of the worm gear and the rotational axis of the gear are perpendicular to each other, there are problems of enlargement of the potentiometer and increase in the mounting surface of the potentiometer.

[0012] An object of the present invention is to provide a rotational angle detection device capable of reducing costs and achieving thinning.

[0013] Solution to the problem

[0014] To achieve the above object, the rotation angle detection device of the present invention includes:

[0015] A housing;

[0016] A rotating shaft rotatably disposed on the housing;

[0017] A rotating body configured to rotate integrally with the rotating shaft;

[0018] A first internal gear concentrically disposed with the rotating shaft and fixed to the housing;

[0019] A second internal gear concentrically disposed with the rotating shaft, having a different number of teeth from that of the first internal gear, and rotatably disposed on the housing;

[0020] An external gear rotatably disposed at a position spaced apart from the rotating shaft in the rotating body and meshing with the first internal gear and the second internal gear; and

[0021] A detection unit for detecting the rotation angle of the second internal gear.

[0022] Advantages of the invention

[0023] According to the rotation angle detection device of the present invention, cost can be reduced and thinning can be achieved. Description of the drawings

[0024] Figure 1 It is a top view showing an example of the rotation angle detection device according to an embodiment of the present invention.

[0025] Figure 2 It is a front view showing an example of the rotation angle detection device according to an embodiment of the present invention.

[0026] Figure 3 It is Figure 1 A sectional view taken along line A-A of

[0027] Figure 4 It is a partial exploded perspective view showing a part of the rotation angle detection device.

[0028] Figure 5 It is a perspective view showing the inside of the rotation angle detection device.

[0029] Figure 6 It is Figure 2 A sectional view taken along line B-B of

[0030] Figure 7 It is Figure 3 A partial enlarged view of

[0031] Figure 8 This is a diagram showing an example of the correspondence between the rotational speed of the shaft and the output level.

[0032] Figure 9 This is an exploded perspective view showing an example of a rotational angle detection device.

[0033] Explanation of reference numerals

[0034] 1 Rotational angle detection device

[0035] 10 Housing

[0036] 10a Hole

[0037] 11 First space

[0038] 11a, 12a, 13a Surfaces

[0039] 11b, 12b, 13b Inner circumferential surfaces

[0040] 12 Second space

[0041] 13 Third space

[0042] 20 Mounting screw

[0043] 30 Shaft

[0044] 32 Lower end portion

[0045] 35 E-ring

[0046] 40 Rotating body

[0047] 42 Outer fitting portion

[0048] 44 Arm portion

[0049] 46 Rod portion

[0050] 50 Fixed-side internal gear

[0051] 60 Movable-side internal gear

[0052] 70 External gear

[0053] 80 Detection portion

[0054] 82 Magnet

[0055] 84 Integrated circuit

[0056] 85 Magnetic sensor

[0057] 90 Wiring board

[0058] 92 Spacer

[0059] 95 leads

[0060] 96 sealing member Detailed implementation manners

[0061] Next, the implementation manners of the present invention will be described with reference to the drawings.

[0062] Figure 1 FIG. is a top view showing an example of the rotation angle detection device 1 according to the implementation manner of the present invention. Figure 2 FIG. is a front view showing an example of the rotation angle detection device 1 according to the implementation manner of the present invention. Figure 3 is Figure 1 sectional view taken along line A-A of Figure 2 The X-axis and Y-axis are depicted in. In Figure 2 , the up-and-down direction is referred to as the "X direction" or "axial direction", the upper side is referred to as the "upper side", "+X side" or "+X direction", and the lower side is referred to as the "lower side", "-X side" or "-X direction". In Figure 2 , the left-and-right direction is referred to as the "Y direction" or "radial direction", the direction away from the X-axis is referred to as the "radial outer side" or "+Y direction", and the direction approaching the X-axis is referred to as the "radial inner side" or "-Y direction".

[0063] As Figures 1 to 3 shown, the rotation angle detection device 1 includes: a housing (case) 10, mounting screws 20, a shaft 30 (rotation shaft), a rotating body 40, a fixed-side internal gear 50 (first internal gear), a movable-side internal gear 60 (second internal gear), an external gear 70, a detection unit 80, and a wiring board 90.

[0064] The housing 10 has a substantially cylindrical shape, and a hole 10a extending upward from the lower end is provided at the center of the housing 10. In other words, the housing 10 is a bottomed cylindrical shape, and includes a circular plate portion 10b and a cylindrical portion 10c extending downward from the circular plate portion 10b.

[0065] The outer shape of the circular plate portion 10b is a circular plate shape centered on the X-axis. The outer shape of the cylindrical portion 10c is a cylindrical shape centered on the X-axis. A first space 11 is formed at the deep end side (upper end side) of the hole 10a. The first space 11 is defined by a circular surface 11a facing downward (-X direction) and an inner peripheral surface 11b located at a position lower than the surface 11a and facing the radial inner side (-Y direction).

[0066] A second space 12 (corresponding to the "accommodating space" of the present invention) is formed so as to extend radially outward (+Y direction) from the lower end edge of the inner peripheral surface 11b. The second space 12 is defined by an annular surface 12a located radially outward of the lower end edge of the inner peripheral surface 11b and facing downward (-X direction), and an inner peripheral surface 12b located below the surface 12a and facing radially inward (-Y direction).

[0067] A third space 13 is formed so as to extend radially outward (+Y direction) from the lower end edge of the inner peripheral surface 12b. The third space 13 is defined by an annular surface 13a located radially outward of the lower end edge of the inner peripheral surface 12b and facing downward (-X direction), and an inner peripheral surface 13b located below the surface 13a and facing radially inward (-Y direction).

[0068] The mounting screw 20 is insert-molded at the center of the circular plate portion 10b of the housing 10. The mounting screw 20 has a through hole 22 extending in the axial direction (X direction).

[0069] The shaft 30 is rotatably disposed on the housing 10. The shaft 30 extends in the vertical direction (X direction). The shaft 30 is rotatably supported by the mounting screw 20. The shaft 30 is inserted into the through hole 22. The lower end portion 32 of the shaft 30 projects into the first space 11.

[0070] The E-ring 35 is fitted onto the shaft 30. By abutting the E-ring 35 against the peripheral portion of the upper port of the through hole 22, the movement of the shaft 30 in the -X direction is restricted. The lower end portion of the shaft 30 is insert-molded in the rotating body 40. By abutting the rotating body 40 against the surface 11a, the movement of the shaft 30 in the +X direction is restricted.

[0071] Figure 4 is a partial exploded perspective view showing a part of the rotation angle detection device 1.

[0072] As Figure 3 and Figure 4 shown, the rotating body 40 has a fitting portion 42, an arm portion 44, and a rod portion 46. As described above, the lower end portion of the shaft 30 is insert-molded in the rotating body 40. Thus, the rotating body 40 rotates integrally with the shaft 30. Specifically, the fitting portion 42 is fitted onto the lower end portion 32 of the shaft 30 from the outside. The arm portion 44 extends radially outward (+Y direction) from the fitting portion 42. The rod portion 46 is disposed at the front end portion of the arm portion 44. The rod portion 46 extends in the vertical direction (X direction).

[0073] Figure 5 is a perspective view showing the inside of the rotation angle detection device 1. Figure 6 is Figure 2 a sectional view taken along line B-B of

[0074] As Figure 3 、 Figure 5 and Figure 6 shown, the tooth portion of the fixed-side internal gear 50 is formed on the lower end side of the inner circumferential surface 11b. The number of teeth of the fixed-side internal gear 50 is, for example, 36 teeth.

[0075] As Figure 3 、 Figure 5 and Figure 6 shown, the movable-side internal gear 60 is rotatably fitted into the second space 12. Specifically, the movable-side internal gear 60 is rotatably fitted into the space defined by the surface 12a, the upper end surface 92b (described later) of the spacer 92, and the inner circumferential surface 12b, and the spacer 92 is disposed in contact with the surface 13a. The movable-side internal gear 60 is arranged to overlap the fixed-side internal gear 50 in the vertical direction (X direction). In other words, the fixed-side internal gear 50 and the movable-side internal gear 60 are arranged in two levels, one above the other.

[0076] As Figure 3 shown, the movable-side internal gear 60 has a disk shape, and a hole 60a that is recessed downward from the upper end is provided at the center of the movable-side internal gear 60. In other words, the movable-side internal gear 60 includes a disk-shaped bottom portion 60b and an annular portion 60c that extends upward from the disk-shaped bottom portion 60b.

[0077] The disk-shaped bottom portion 60b has a fitting recess 60d. The fitting recess 60d is a hole that opens downward. The fitting recess 60d has the downward-facing surface of the disk-shaped bottom portion 60b as the bottom wall surface. The peripheral wall of the fitting recess 60d protrudes from the second space 12 into the third space 13.

[0078] As Figure 3 shown, the tooth portion of the movable-side internal gear 60 is formed on the inner circumferential surface of the annular portion 60c. The number of teeth of the movable-side internal gear 60 is, for example, 35 teeth.

[0079] Figure 7 is Figure 3 A partial enlarged view. As Figure 3 and Figure 7As shown, the inner peripheral surface 12b is spaced apart from the outer peripheral surface of the annular portion 60c in the radially outer direction (+Y direction). Thus, a gap GP is provided between the outer peripheral surface of the annular portion 60c and the inner peripheral surface 12b. The gap GP extends in the radially outer direction (+Y direction) with respect to the annular portion 60c. The size of the gap GP is 0.5% to 5% of the diameter of the movable-side internal gear 60. In addition, the gap GP on the lower end side (-X side) of the outer peripheral portion of the movable-side internal gear 60 is wider than the gap GP on the upper end side (+X side) of the outer peripheral portion of the movable-side internal gear 60. Moreover, at the gap GP on the -X side, the inner peripheral surface 12b is inclined in the radially outer direction (+Y direction) with respect to the -X direction. Thus, the gap GP on the -X side expands more and more in the radially outer direction as it goes from the upper side to the lower side. A lubricant with a consistency of 200 to 350 is accommodated in the gap GP.

[0080] As Figures 3 to 6 shown, the external gear 70 is rotatably supported by the rod portion 46. The external gear 70 meshes with the fixed-side internal gear 50 and the movable-side internal gear 60.

[0081] The rotating body 40, the fixed-side internal gear 50, the movable-side internal gear 60, and the external gear 70 constitute an epicyclic mechanism. For example, the fixed-side internal gear 50 has 36 teeth, and the movable-side internal gear 60 has 35 teeth. Thus, when the shaft 30 rotates 36 revolutions, the movable-side internal gear 60 rotates 1 revolution in the rotation direction of the shaft 30. That is, the reduction ratio of the movable-side internal gear 60 with respect to the rotating body 40 (shaft 30) is 1 / 36. In other words, when the rotational speed of the shaft 30 is N (N is a natural number), the rotational speed of the movable-side internal gear 60 is N / 36. Therefore, in the rotation angle detection device 1 of the present embodiment, the detectable range when detecting the rotation angle of the rotating member or the reel is the range from when the shaft 30 rotates 0 degrees to when the shaft 30 rotates 36 revolutions (= 36 * 360 degrees).

[0082] As Figure 3 shown, the detection unit 80 includes a magnet 82 and an integrated circuit 84. The magnet 82 is disposed on the disk-shaped bottom 60b. Specifically, the magnet 82 is fitted in the fitting recess 60d. For example, a disk-shaped neodymium magnet magnetized in the radial direction or the like is used as the magnet 82.

[0083] The integrated circuit 84 is mounted on the wiring board 90. The integrated circuit 84 has a magnetic sensor 85. The magnetic sensor 85 is disposed opposite to the magnet 82 so as to be spaced apart from the magnet 82 by a predetermined distance in the vertical direction (X direction). The magnetic sensor 85 converts the direction of the magnetic field emitted by the magnet 82 into a change in an electrical signal (such as voltage) and outputs the change in the electrical signal.

[0084] Figure 8It is a diagram showing an example of the correspondence relationship between the rotational speed of the shaft 30 and the output level output from the magnetic sensor 85. Figure 8 The horizontal axis represents the rotational speed of the shaft 30, and the vertical axis represents the output level (%). According to Figure 8 the shown correspondence relationship, for example, when the shaft 30 rotates 18 turns, the output level of the magnetic sensor 85 is 50%. Additionally, when the shaft 30 rotates 36 turns, the output level of the magnetic sensor 85 is 100%.

[0085] Figure 9 It is an exploded perspective view showing an example of the rotational angle detection device 1.

[0086] As Figure 9 shown, the outer shape of the spacer 92 is tubular. Additionally, as Figure 3 shown, the spacer 92 is configured such that its outer peripheral surface 92a is along the inner peripheral surface 13b and its upper end surface 92b abuts against the surface 13a. The upper end surface 92b extends radially inward (-Y direction) from the surface 13a. As described above, the surface 12a extending in the -Y direction and the inner peripheral surface 12b together define a receiving space in which the movable-side internal gear 60 is engaged. Additionally, in order to space apart the magnet 82 disposed on the disk-shaped bottom 60b and the magnetic sensor 85 disposed on the wiring board 90 by a predetermined distance, the spacer 92 has a predetermined length in the tube axis direction (vertical direction).

[0087] As Figure 9 shown, the outer shape of the wiring board 90 is disk-shaped. As Figure 3 shown, the wiring board 90 is fitted into the third space 13. The wiring board 90 is fixed to the lower end surface 92c of the spacer 92 with an adhesive. Thus, the wiring board 90 is disposed at a distance from the disk-shaped bottom 60b on which the magnet 82 is disposed. The lead wire 95 is connected to the wiring on the wiring board 90. The gap between the outer peripheral surface of the wiring board 90 and the inner peripheral surface 13b is blocked with a sealing member 96.

[0088] The rotational angle detection device 1 of the above-described embodiment includes: a housing 10; a shaft 30 rotatably disposed on the housing 10; a rotating body 40 configured to rotate integrally with the shaft 30; a fixed-side internal gear 50 concentrically disposed with the shaft 30 and fixed to the housing 10; a movable-side internal gear 60 concentrically disposed with the shaft 30, having a different number of teeth from the fixed-side internal gear 50, and rotatably disposed on the housing 10; an outer gear 70 rotatably disposed at a position spaced apart from the shaft 30 in the rotating body 40 and meshing with the fixed-side internal gear 50 and the movable-side internal gear 60; and a detection unit 80 that detects the rotational angle of the movable-side internal gear 60.

[0089] With the above structure, the movable-side internal gear 60 is rotatably disposed on the housing 10, and the external gear 70 is engaged with the fixed-side internal gear 50 and the movable-side internal gear 60, whereby a large reduction ratio can be obtained. Therefore, it is not necessary to reduce the diameter of the fixed-side internal gear 50 or the movable-side internal gear 60, and it is not necessary to improve the dimensional accuracy and assembly accuracy of the movable-side internal gear 60 or the like. Thereby, the cost can be reduced. In addition, since it is not necessary to arrange the gears in multiple stages, the device can be made thinner.

[0090] In addition, the rotation angle detection device 1 of the above embodiment is configured such that the fixed-side internal gear 50 and the movable-side internal gear 60 overlap in the vertical direction. Thereby, the device can be made further thinner.

[0091] In addition, the internal cycloid mechanism of the above embodiment can obtain a large reduction ratio even when the number of gears is small. Thereby, the number of components can be reduced, and thus the cost can be reduced.

[0092] In addition, in the rotation angle detection device 1 of the above embodiment, even when the gap GP between the movable-side internal gear 60 and the housing 10 becomes narrower due to external stress or thermal shrinkage of each component, the size of the gap GP is between 0.5% and 5% of the diameter of the movable-side internal gear 60. Thereby, it is possible to avoid the situation where the movable-side internal gear 60 cannot rotate.

[0093] In addition, the gap GP on the -X side (the lower end side of the outer peripheral portion of the movable-side internal gear 60) of the rotation angle detection device 1 of the above embodiment is wider than the gap GP on the +X side (the upper end side of the outer peripheral portion of the movable-side internal gear 60). Moreover, the gap GP on the -X side becomes wider as it gets closer to the -X side. Thus, when a large external force is applied to the housing 10, although the gap GP on the -X side, which is set wider, becomes narrower, it still maintains a specified width, so it is possible to prevent the situation where the movable-side internal gear 60 cannot rotate.

[0094] In addition, the rotation angle detection device 1 of the above embodiment accommodates a lubricant having a consistency of 200 to 350 in the gap GP. It is possible to prevent the movable-side internal gear 60 from unexpectedly moving within the gap GP. Thereby, it is possible to prevent the generation of noise and vibration.

[0095] In addition, the above embodiments only represent an example of the implementation when implementing the present invention, and the technical scope of the present invention should not be limited by these embodiments. That is, the present invention can be implemented in various forms without departing from its gist or its main features.

[0096] In the above-described embodiment, the case where the rotation angle of the movable-side internal gear 60 is detected using the detection unit 80 having the magnet 82 and the magnetic sensor 85 is shown. However, the present invention is not limited thereto. For example, it may be a method of irradiating visible light or infrared rays to the movable-side internal gear 60 and detecting the rotation angle of the movable-side internal gear 60 based on the change in the amount of light reflected or transmitted by the movable-side internal gear 60, or a contact-type detection unit in which a brush is used instead of the magnet 82 and a resistor is used instead of the magnetic sensor 85.

[0097] This application is based on Japanese Patent Application No. 2019-220280 filed on December 5, 2019, the content of which is incorporated herein by reference.

[0098] Industrial Applicability

[0099] The present invention is suitable for a rotation angle detection device that requires cost reduction and thinning.

Claims

1. A rotation angle detection device, comprising: A housing; A rotating shaft rotatably disposed on the housing; A rotating body configured to rotate integrally with the rotating shaft; A first internal gear concentrically disposed with the rotating shaft, having an internal tooth structure with tooth portions formed on the inner peripheral surface opposite to the rotating shaft, and fixed to the housing; A second internal gear concentrically disposed with the rotating shaft so as to overlap the first internal gear in the direction along the rotating shaft, having an internal tooth structure with tooth portions formed with a number of teeth different from that of the first internal gear, and rotatably disposed on the housing; An external gear disposed at a position spaced apart from the rotating shaft in the rotating body so as to be able to rotate inside the first internal gear and the second internal gear, having tooth portions formed on the outer peripheral surface corresponding to the inner peripheral surfaces of the first internal gear and the second internal gear, and the tooth portions formed on the outer peripheral surface meshing with the respective tooth portions of the first internal gear and the second internal gear; And A detection unit that detects the rotation angle of the second internal gear based on the rotation amount of the second internal gear.

2. The rotation angle detection device according to claim 1, wherein The housing has a receiving space into which the second internal gear is rotatably inserted.

3. The rotation angle detection device according to claim 2, wherein The size of the gap between the outer peripheral surface of the second internal gear and the inner peripheral surface of the receiving space is 0.5% to 5% of the diameter of the second internal gear.

4. The rotation angle detection device according to claim 3, wherein The gap extends radially with respect to the second internal gear.

5. The rotation angle detection device according to claim 4, wherein The gap expands more and more radially outward as it goes from one side to the other side in the direction of the rotating shaft.

6. The rotation angle detection device according to any one of claims 3 to 5, wherein The consistency of the lubricant contained in the gap is 200 to 350.

7. The rotational angle detection device according to claim 1, wherein, The detection unit has: A magnet disposed on the second internal gear; and An integrated circuit including a magnetic sensor disposed opposite to the magnet, which converts the direction of the magnetic field emitted by the magnet into a change in an electrical signal and outputs the change in the electrical signal.

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