JP7277190B2 - absolute encoder - Google Patents

Description

The present invention relates to absolute encoders.

2. Description of the Related Art Conventionally, rotary encoders are known that are used to detect the position and angle of movable elements in various types of control machinery. Such encoders include incremental encoders that detect relative positions or angles, and absolute encoders that detect absolute positions or angles. For example, Patent Literature 1 discloses an absolute-type rotary actuator equipped with a plurality of magnetic encoder units that detect the angular positions of the main shaft and sub-shafts using magnetism, and measuring the absolute position of the main shaft from the detection results. Encoders are listed.

JP 2013-24572 A

However, in the magnetic encoder disclosed in Patent Document 1, for example, a part of the magnetic flux generated by each of the plurality of adjacent permanent magnets does not correspond to each of the plurality of permanent magnets. , the detection accuracy may deteriorate due to the influence of noise due to external factors other than the magnetic flux from the permanent magnet that is originally desired to be detected.

The present invention has been made in view of the above, and is intended to reduce the adverse effects of leakage magnetic flux from permanent magnets that should not be detected on a magnetic sensor that detects magnetic flux from permanent magnets that should be detected. An object of the present invention is to provide an absolute encoder that enables

An absolute encoder according to an embodiment of the present invention includes a first driving gear that rotates according to the rotation of a main shaft, a first permanent magnet provided on the tip side of the first driving gear, and a magnetic flux generated from the first permanent magnet. a first angle sensor for detecting the rotation angle of the first driving gear corresponding to a change in the first driven gear whose central axis is perpendicular to the central axis of the first driving gear and meshes with the first driving gear; a second drive gear provided coaxially with the first driven gear and rotating according to the rotation of the first driven gear; and a central axis orthogonal to the central axis of the first driven gear and meshing with the second drive gear. a second driven gear; a second permanent magnet provided on the tip side of the second driven gear; an angle sensor; and a first magnetic flux shield that surrounds at least part of the periphery of the first drive gear and the second driven gear.

ADVANTAGE OF THE INVENTION The absolute encoder which concerns on this invention is effective in the ability to reduce the influence of leakage magnetic flux with respect to a magnetic sensor.

FIG. 2 is a perspective view showing a state where absolute encoder 100-1 according to Embodiment 1 of the present invention is attached to motor 200; FIG. 2 is a perspective view showing a state in which a lid portion 116 is removed from a case 115 shown in FIG. 1; FIG. 3 is a perspective view showing a state in which a board 120 and board mounting screws 122 are removed from the absolute encoder 100-1 shown in FIG. 2; 4 is a bottom view of the substrate 120; FIG. FIG. 4 is a plan view of the absolute encoder 100-1 shown in FIG. 3; FIG. 2 is a cross-sectional view of the absolute encoder 100-1 cut along a plane parallel to the XZ plane passing through the center of the motor shaft 201; However, the second subshaft gear 138 and the magnetic sensor 90 are shown. FIG. 2 is a cross-sectional view of the absolute encoder 100-1 taken along a plane perpendicular to the center line of the first intermediate gear 102 and passing through the center of the first countershaft gear 105; FIG. 4 is a cross-sectional view of the absolute encoder 100-1 cut along a plane parallel to the Z-axis direction passing through the center of the second subshaft gear 138 and the center of the second intermediate gear 133, viewed from the substantially right side; FIG. 2 is a diagram showing the functional configuration of a microcomputer 121 included in the absolute encoder 100-1 according to Embodiment 1 of the present invention; FIG. 4 is a diagram showing a first modification of the absolute encoder 100-1 according to Embodiment 1 of the present invention; FIG. 11 is a perspective view of the magnetic flux shield 500 shown in FIG. 10; FIG. 11 is a vertical cross-sectional view of the magnetic flux shielding portion 500 shown in FIG. 10; FIG. 5 is a plan view showing a second modification of the absolute encoder 100-1 according to Embodiment 1 of the present invention; FIG. 14 is a perspective view of the magnetic flux shielding portion 501 and the magnetic flux shielding portion 502 shown in FIG. 13; FIG. 14 is a vertical cross-sectional view of the magnetic flux shielding portion 502 shown in FIG. 13; FIG. 11 is a perspective view showing a state in which an absolute encoder 100-2 according to Embodiment 2 of the present invention is attached to a motor 200; FIG. 17 is a perspective view showing a state in which a case 15 and mounting screws 16 are removed from the absolute encoder 100-2 shown in FIG. 16; FIG. 18 is a perspective view showing a state in which the substrate 20 and the substrate mounting screws 13 are removed from the absolute encoder 100-2 shown in FIG. 17; 19 is a perspective view showing a state in which the motor 200 and the screw 14 are removed from the perspective view in which the absolute encoder 100-2 shown in FIG. 18 is attached to the motor 200; FIG. The figure which shows the state which planarly viewed the main base 10, the intermediate gear 2, etc. which are shown by FIG. FIG. 21 is a cross-sectional view of the absolute encoder 100-2 shown in FIG. 20 taken along a plane passing through the center of the intermediate gear 2 and parallel to the XY plane; FIG. 22 is an enlarged partial cross-sectional view showing a state in which the bearing 3 shown in FIG. 21 is removed from the intermediate gear 2; FIG. 21 is a cross-sectional view of the absolute encoder 100-2 shown in FIG. 17 taken along a plane passing through the center of the main shaft gear 1 shown in FIG. 20 and perpendicular to the center line of the intermediate gear 2; However, the substrate 20 and the magnetic sensor 40 are not sectioned. FIG. 21 is a cross-sectional view of the absolute encoder 100-2 shown in FIG. 17 taken along a plane that passes through the center of the countershaft gear 5 shown in FIG. 21 and is perpendicular to the centerline of the intermediate gear 2; However, the substrate 20 and the magnetic sensor 50 are not sectioned. FIG. 19 is a perspective view showing a state in which an intermediate gear 2 is removed from among the multiple parts shown in FIG. 18; FIG. 25 shows a state in which the screw 12 is removed from the wall portion 70, a state of the plate spring 11 after the screw 12 is removed, and a wall portion 70 provided with a plate spring mounting surface 10e facing the plate spring 11. The perspective view which shows this. However, the motor 200 and the main shaft gear 1 are not shown. FIG. 17 is a cross-sectional view of the absolute encoder 100-2 shown in FIG. 17 taken along a plane parallel to the Z-axis direction passing through the center of the substrate positioning pin 10g and the center of the substrate positioning pin 10j shown in FIG. 20; However, the magnetic sensor 40 is not sectioned. The figure which looked at the board|substrate 20 shown by FIG. 17 from the lower surface 20-1 side. A view of the state shown in FIG. 16 with the motor 200 removed and viewed from the lower surface 10-2 side of the main base 10. FIG. FIG. 17 is a perspective view of the case 15 shown in FIG. 16; 17 is a cross-sectional view of the absolute encoder 100-2 shown in FIG. 16 taken along a plane parallel to the Z-axis direction passing through the center of the substrate positioning pin 10g and the center of the substrate positioning pin 10j shown in FIG. 18; FIG. However, the motor 200 and the main shaft gear 1 are not sectioned. FIG. 25 is an exploded perspective view of the permanent magnet 8, magnet holder 6, countershaft gear 5 and bearing 7 shown in FIG. 24; 24 is an exploded perspective view of the permanent magnet 9, main shaft gear 1 and motor shaft 201 shown in FIG. 23; FIG. Waveform (A) obtained by detecting the magnetic flux of the permanent magnet 9 provided on the main shaft gear 101 (main shaft gear 1) by the magnetic sensor 40, and the magnetic flux of the permanent magnet 8 provided on the first sub shaft gear 105 (sub shaft gear 5). Waveform (B) of the magnetic flux detected by the magnetic sensor 50 and magnetic interference waveform (C) detected by the magnetic sensor 40 in a state in which part of the magnetic flux of the permanent magnet 8 is superimposed on the magnetic flux of the permanent magnet 9 as leakage flux. Conceptual diagram. Waveform (A) obtained by detecting the magnetic flux of the permanent magnet 8 provided on the first subshaft gear 105 (subshaft gear 5) by the magnetic sensor 50, and the magnetic flux of the permanent magnet 9 provided on the main shaft gear 101 (main shaft gear 1). Waveform (B) of the magnetic flux detected by the magnetic sensor 40 and magnetic interference waveform (C) detected by the magnetic sensor 50 in a state in which part of the magnetic flux of the permanent magnet 9 is superimposed on the magnetic flux of the permanent magnet 8 as leakage flux. Conceptual diagram. FIG. 10 is a diagram showing the functional configuration of a microcomputer 21 included in an absolute encoder 100-2 according to Embodiment 2 of the present invention; FIG. 11 is a plan view showing a modification of the absolute encoder 100-2 according to the second embodiment of the present invention; FIG. 38 is a perspective view showing a state in which an intermediate gear 2 is removed from among the multiple parts shown in FIG. 37; FIG. 38 is a cross-sectional view of the magnetic flux shielding portion 61 shown in FIG. 37; FIG. 38 is a cross-sectional view of the magnetic flux shielding portion 62 shown in FIG. 37; FIG. 4 shows a permanent magnet 9A applicable to absolute encoders 100-1 and 100-2 of the first and second embodiments; FIG. 4 shows a permanent magnet 9B applicable to absolute encoders 100-1 and 100-2 of the first and second embodiments;

A configuration of an absolute encoder according to an embodiment of the present invention will be described in detail below with reference to the drawings. In addition, this invention is not limited by this embodiment.

<Embodiment 1>
FIG. 1 is a perspective view showing a state where absolute encoder 100-1 according to Embodiment 1 of the present invention is attached to motor 200. FIG. The following description is based on the XYZ orthogonal coordinate system. The X-axis direction corresponds to the horizontal left-right direction, the Y-axis direction corresponds to the horizontal front-back direction, and the Z-axis direction corresponds to the vertical up-down direction. The Y-axis direction and the Z-axis direction are orthogonal to the X-axis direction. The X-axis direction may be referred to as the leftward or rightward direction, the Y-axis direction as the forward direction or the rearward direction, and the Z-axis direction as the upward direction or downward direction. In FIG. 1, a state viewed from above in the Z-axis direction is called a plan view, a state viewed from the front in the Y-axis direction is called a front view, and a state viewed from the left and right in the X-axis direction is called a side view. Such direction notation does not limit the use attitude of the absolute encoder 100-1, and the absolute encoder 100-1 can be used in any attitude. Note that the shape of the tooth portion is omitted in the drawings.

FIG. 2 is a perspective view showing a state in which lid portion 116 is removed from case 115 shown in FIG. FIG. 3 is a perspective view showing a state in which the substrate 120 and the substrate mounting screws 122 are removed from the absolute encoder 100-1 shown in FIG. 4 is a bottom view of the substrate 120. FIG. FIG. 5 is a plan view of absolute encoder 100-1 shown in FIG. FIG. 6 is a cross-sectional view of the absolute encoder 100-1 cut along a plane that passes through the center of the motor shaft 201 and is parallel to the XZ plane. However, the second subshaft gear 138 and the magnetic sensor 90 are shown. FIG. 7 is a sectional view of the absolute encoder 100-1 taken along a plane perpendicular to the center line of the first intermediate gear 102 and passing through the center of the first countershaft gear 105. FIG. Illustration of the case 115 and the lid portion 116 is omitted in FIG. FIG. 8 is a cross-sectional view of the absolute encoder 100-1 cut along a plane parallel to the Z-axis direction passing through the center of the second subshaft gear 138 and the center of the second intermediate gear 133, viewed substantially from the right side. . Also, in FIG. 8, the illustration of the case 115 and the lid portion 116 is omitted.

The configuration of the absolute encoder 100-1 will be described in detail below with reference to FIGS. 1 to 8. FIG. The absolute encoder 100-1 is an absolute type encoder that specifies and outputs the amount of rotation of the main shaft of the motor 200 over a plurality of rotations. Motor 200 may be, for example, a stepping motor or a DC brushless motor. As an example, the motor 200 may be applied as a driving source for driving an industrial robot through a reduction mechanism such as a strain wave gearing. A motor shaft 201 of the motor 200 protrudes to both sides of the motor 200 in the Z-axis direction. Absolute encoder 100-1 outputs the amount of rotation of motor shaft 201 as a digital signal. Note that the motor shaft 201 is an example of a main shaft.

Absolute encoder 100-1 is provided at the end of motor 200 in the Z-axis direction. Although there is no particular limitation on the shape of the absolute encoder 100-1, in the embodiment, the absolute encoder 100-1 has a substantially rectangular shape in a plan view, and extends in the main axis extension direction (hereinafter referred to as In the first embodiment, the axial direction is a direction parallel to the Z-axis direction) and has a thin horizontally long rectangular shape. That is, the absolute encoder 100-1 has a rectangular parallelepiped shape that is flattened in the Z-axis direction.

The absolute encoder 100-1 has a hollow rectangular tubular case 115 that houses the internal structure. The case 115 includes a plurality (eg, four) of outer wall portions 115a, 115b, 115c, and 115d surrounding at least the main shaft and the intermediate rotor. A lid portion 116 is fixed to the ends of the outer wall portion 115 a , the outer wall portion 115 b , the outer wall portion 115 c and the outer wall portion 115 d of the case 115 . The lid portion 116 is a plate-like member that has a substantially rectangular shape in plan view and is thin in the axial direction.

The outer wall portion 115a, the outer wall portion 115b, the outer wall portion 115c, and the outer wall portion 115d are connected in this order. The outer wall portion 115a and the outer wall portion 115c are provided parallel to each other. The outer wall portion 115b and the outer wall portion 115d span the side ends of the outer wall portion 115a and the outer wall portion 115c and are provided parallel to each other. In this example, the outer wall portions 115a and 115c extend in the X-axis direction in plan view, and the outer wall portions 115b and 115d extend in the Y-axis direction in plan view.

Absolute encoder 100 - 1 includes main base 110 , case 115 , lid 116 , substrate 120 , leaf spring 111 , and multiple screws 164 . The main base 110 is a base that supports each rotating body and each gear. The main base 110 includes a base portion 110 a , a plurality of (for example, four) struts 141 , and shafts 106 , 134 and 139 .

A base portion 110a of the main base 110 is a plate-like portion facing the motor 200 side of the absolute encoder 100-1 and extends in the X-axis direction and the Y-axis direction. A hollow rectangular tubular case 115 is fixed to the base portion 110 a of the main base 110 with a plurality of (for example, three) screws 164 .

A column 141 provided on the main base 110 is a substantially cylindrical portion that protrudes axially away from the motor 200 from the base 110 a and supports the substrate 120 . A substrate 120 is fixed to the protruding end of the column 141 using a substrate mounting screw 122 . FIG. 2 shows how the substrate 120 is provided to cover the inside of the encoder. The board 120 is a plate-like printed wiring board that has a substantially rectangular shape in plan view and is thin in the axial direction. The substrate 120 mainly mounts the magnetic sensor 50 , the magnetic sensor 40 , the magnetic sensor 90 and the microcomputer 121 .

The absolute encoder 100-1 includes a main shaft gear 101, a worm gear portion 101c, a worm wheel portion 102a, a first intermediate gear 102, a first worm gear portion 102b, a worm wheel portion 105a, a first countershaft gear 105, and a second worm gear portion 102h. , and a worm wheel portion 133a. Also, the absolute encoder 100-1 includes a second intermediate gear 133, a fourth driving gear portion 133d, a fourth driven gear portion 138a, a second counter shaft gear 138, a permanent magnet 8, a permanent magnet 9, a permanent magnet 17, a magnetic sensor 50 , the magnetic sensor 40 , the magnetic sensor 90 , and the microcomputer 121 .

The main shaft gear 101 rotates according to the rotation of the motor shaft 201, and transmits the rotation of the motor shaft 201 to the worm gear portion 101c. As shown in FIG. 6, the main shaft gear 101 includes a first cylindrical portion 101a fitted to the outer circumference of the motor shaft 201, a disk portion 101b having a worm gear portion 101c, and a magnet holding portion holding the permanent magnet 9. 101d. The magnet holding portion 101d has a cylindrical concave shape provided in the central portion of the disk portion 101b and the upper end surface of the first cylindrical portion 101a. The first tubular portion 101a, the disk portion 101b, and the magnet holding portion 101d are integrally formed such that their central axes are substantially aligned. The main shaft gear 101 can be made of various materials such as resin material and metal material. The main shaft gear 101 is made of polyacetal resin, for example.

The worm gear portion 101c is an example of a first drive gear that drives the worm wheel portion 102a. In particular, the worm gear portion 101c is a worm gear with the number of threads=1 formed on the outer circumference of the disk portion 101b. The rotation axis of the worm gear portion 101 c extends in the axial direction of the motor shaft 201 .

As shown in FIG. 5 , the first intermediate gear 102 is a gear portion that transmits the rotation of the main shaft gear 101 to the worm wheel portion 105 a and the second intermediate gear 133 . The first intermediate gear 102 is supported by a shaft 104 around a rotation axis La extending substantially parallel to the base portion 110a. The first intermediate gear 102 is a substantially cylindrical member extending in the direction of its rotation axis La. The first intermediate gear 102 includes a base portion 102c, a first cylindrical portion 102d having a worm wheel portion 102a, a second cylindrical portion 102e having a first worm gear portion 102b, and a second worm gear portion 102h. A through hole is formed inside, and the shaft 104 is inserted through the through hole. The first intermediate gear 102 is pivotally supported by inserting the shaft 104 through holes formed in a support portion 110b and a support portion 110c provided in the base portion 110a of the main base 110 . Grooves are provided near both ends of the shaft 104 projecting outward from the support portions 110b and 110c, respectively, and a retaining ring 107 and a retaining ring 108 are fitted into the grooves to prevent the shaft 104 from coming off. , the shaft 104 is prevented from coming off.

The outer wall portion 115 a is provided on the side of the first intermediate gear 102 opposite to the motor shaft 201 . The outer wall portion 115c is provided on the side of the first intermediate gear 102 on which the motor shaft 201 is arranged, parallel to the outer wall portion 115a. The first intermediate gear 102 may be arranged so that its rotational axis La faces in any direction. The rotation axis La of the first intermediate gear 102 is inclined in a range of 5° to 30° with respect to the extending direction of the outer wall portion 115a provided on the side opposite to the motor shaft 201 of the first intermediate gear 102 in plan view. may be provided as In the example of FIG. 5, the rotation axis La of the first intermediate gear 102 is inclined by 20° with respect to the extending direction of the outer wall portion 115a. In other words, the case 115 includes an outer wall portion 115a extending in a direction inclined in a range of 5° to 30° with respect to the rotation axis La of the first intermediate gear 102 in plan view. In the example of FIG. 5, the inclination Ds between the extending direction of the outer wall portion 115a and the rotation axis La of the first intermediate gear 102 is set at 20°.

In Embodiment 1, the base portion 102c of the first intermediate gear 102 has a cylindrical shape, and the first cylindrical portion 102d, the second cylindrical portion 102e, and the third cylindrical portion 102f have a cylindrical shape with a diameter larger than that of the base portion 102c. . A through hole is formed in the center of the first intermediate gear 102 . The base portion 102c, the first tubular portion 102d, the second tubular portion 102e, the third tubular portion 102f, and the through hole are integrally formed such that their central axes substantially coincide with each other. The second tubular portion 102e, the first tubular portion 102d, and the third tubular portion 102f are arranged in this order at positions separated from each other. The first intermediate gear 102 can be made of various materials such as resin material and metal material. In Embodiment 1, the first intermediate gear 102 is made of polyacetal resin.

Each of the support portion 110b and the support portion 110c is a projection-shaped member projecting in the positive direction of the Z-axis from the base portion 110a of the main base 110 by cutting and raising a portion of the base portion 110a of the main base 110. is formed with a hole through which the is inserted. Grooves are provided near both ends of the shaft 104 protruding from the support portions 110b and 110c. It prevents from falling out. With this configuration, the first intermediate gear 102 is rotatably supported on the rotation axis La.

The leaf spring 111 will be explained. As the worm wheels of the first intermediate gear 102 are driven by the first worm gear portion 102b and the second worm gear portion 102h, a reaction force acts in the axial direction Td of the first intermediate gear 102, and the position in the axial direction Td is changed to Subject to change. Therefore, in Embodiment 1, the plate spring 111 that applies the biasing force to the first intermediate gear 102 is provided. The leaf spring 111 suppresses positional fluctuation in the axial direction Td by applying a biasing force in the direction of the rotation axis La of the first intermediate gear 102 to the first intermediate gear 102 . The leaf spring 111 includes an attachment portion 111b attached to the base portion 110a of the main base 110, and a sliding portion 111a extending from the attachment portion 111b and contacting the hemispherical protrusion 102g. The mounting portion 111b and the sliding portion 111a are formed of a thin plate-like spring material, and the base of the sliding portion 111a is bent halfway at a substantially right angle with respect to the mounting portion 111b. In this manner, the leaf spring 111 directly contacts and presses the hemispherical projection 102g of the first intermediate gear 102, thereby urging the first intermediate gear 102 in the axial direction Td. Further, the sliding portion 102i of the first intermediate gear 102 contacts and slides on the supporting portion 110c of the main base 110. As shown in FIG. As a result, it is possible to suppress variation in the position of the first intermediate gear 102 in the axial direction Td.

In the first embodiment, the first intermediate gear 102 receives a reaction force from the worm wheel portion 105a of the first countershaft gear 105 due to the rotation of the first worm gear portion 102b that meshes with the worm wheel portion 105a of the first countershaft gear 105. The direction of the force is the direction of the reaction force received by the first intermediate gear 102 from the worm wheel portion 133a of the second intermediate gear 133 as the second worm gear portion 102h meshing with the worm wheel portion 133a of the second intermediate gear 133 rotates. is set to the contrary. That is, the tooth shape of each worm gear is set so that the components of the respective reaction forces in the axial direction Td of the first intermediate gear 102 are directed in opposite directions. Specifically, the inclination directions of the teeth of the worm gears are set so that the axial direction Td components of the respective reaction forces applied to the first intermediate gear 102 are opposite to each other. In this case, the combined reaction force in the axial direction Td is smaller than when the direction of the axial direction Td component of the reaction force received by the first intermediate gear 102 from each worm gear is the same. can be made smaller. As a result, the rotation resistance of the first intermediate gear 102 can be reduced and the gear can be smoothly rotated.

In the above method, the sliding resistance due to the engagement between the worm gear portion 101c of the main shaft gear 101 and the worm wheel portion 102a of the first intermediate gear 102 is relatively small, and the rotation of the main shaft gear 101 gives the first intermediate gear 102 the axial direction Td. is relatively small compared to the reaction force received by the first intermediate gear 102 from the worm wheel portion 105a of the first countershaft gear 105 and the worm wheel portion 133a of the second intermediate gear 133. However, when the sliding resistance of the engagement between the worm gear portion 101c of the main shaft gear 101 and the worm wheel portion 102a of the first intermediate gear 102 is relatively large, the following method is effective.

In FIG. 5, when the main shaft gear 101 rotates to the right, sliding resistance due to meshing between the worm gear portion 101c of the main shaft gear 101 and the worm wheel portion 102a of the first intermediate gear 102 causes the first intermediate gear 102 to move in the axial direction Td. , and the first intermediate gear 102 tries to move rightward. At this time, if the force in the axial direction Td generated by the worm gears at both ends of the first intermediate gear 102 is set to cancel out by the method described above, the worm gear portion of the main shaft gear 101 as described above The rightward force acting on the first intermediate gear 102 is relatively increased due to the sliding resistance due to the meshing of the worm wheel portion 102a of the first intermediate gear 102 with 101c. In order to prevent the rightward movement of the first intermediate gear 102 against the rightward force acting on the first intermediate gear 102, the pressing force of the leaf spring 111 must be increased. As a result, the sliding resistance between the sliding portion 111a of the leaf spring 111 and the hemispherical protrusion 102g of the first intermediate gear 102 that is in contact with and pressed against the sliding portion 111a and the first intermediate gear of the semispherical protrusion 102g The sliding resistance between the sliding portion 102i located at the opposite end of the gear 102 and the supporting portion 110c increases, and the rotation resistance of the first intermediate gear 102 increases.

When the main shaft gear 101 rotates to the right, the first worm gear portion 102b meshing with the worm wheel portion 105a of the first countershaft gear 105 rotates. The direction of the reaction force received by 102 and the rotation of the second worm gear portion 102h meshing with the worm wheel portion 133a of the second intermediate gear 133 cause the first intermediate gear 102 to move from the worm wheel portion 133a of the second intermediate gear 133. By setting the direction of the received reaction force to a force in the direction to move the first intermediate gear 102 to the left with respect to the axial direction Td, the worm gear portion 101c of the main shaft gear 101 and the first intermediate The rightward force acting on the first intermediate gear 102 can be reduced by the sliding resistance caused by the meshing of the gear 102 with the worm wheel portion 102a. As a result, the biasing force applied to the first intermediate gear 102 by the leaf spring 111 can be reduced. As a result, the rotation resistance of the first intermediate gear 102 can be reduced and the gear can be smoothly rotated.

On the other hand, when the main shaft gear 101 rotates to the left, the first intermediate gear 102 moves in the axial direction Td due to the sliding resistance caused by the engagement between the worm gear portion 101c of the main shaft gear 101 and the worm wheel portion 102a of the first intermediate gear 102. , and the first intermediate gear 102 tries to move to the left. At this time, the reaction forces received by the first worm gear portion 102b and the second worm gear portion 102h at both ends of the first intermediate gear 102 are forces that move the first intermediate gear 102 to the right. Therefore, also in this case, the leftward force acting on the first intermediate gear 102 can be reduced. Since the biasing force applied to the first intermediate gear 102 by the leaf spring 111 is always leftward with respect to the axial direction Td, the leftward force acting on the first intermediate gear 102 due to the meshing of the three gears is reduced. Accordingly, the total leftward force applied to the first intermediate gear 102 is also reduced. As a result, the rotational resistance due to sliding between the sliding portion 102i on the left end of the first intermediate gear 102 in the drawing and the support portion 110c provided on the base portion 110a of the main base 110 can be reduced.

In FIG. 5 , the worm wheel portion 102 a is an example of a first driven gear meshing with the worm gear portion 101 c of the main shaft gear 101 . The worm wheel portion 102a is a worm wheel having 20 teeth formed on the outer circumference of the first tubular portion 102d. The worm gear portion 101c and the worm wheel portion 102a constitute a first worm transmission mechanism. The rotation axis of the worm wheel portion 102 a extends in a direction perpendicular to the axial direction of the motor shaft 201 .

When the number of threads of the worm gear portion 101c of the main shaft gear 101 is 1 and the number of teeth of the worm wheel portion 102a of the first intermediate gear 102 is 20, the reduction ratio is 20. That is, when the main shaft gear 101 makes 20 rotations, the first intermediate gear 102 makes 20/20=1 rotation.

The first worm gear portion 102 b is an example of a second drive gear that drives the worm wheel portion 105 a and is a gear portion of the first intermediate gear 102 . In particular, the first worm gear portion 102b is a worm gear with five threads formed on the outer circumference of the second tubular portion 102e. The rotation axis of the first worm gear portion 102 b extends in a direction perpendicular to the axial direction of the motor shaft 201 .

5 and 7, the first countershaft gear 105 is decelerated and rotates together with the permanent magnet 8 as the motor shaft 201 rotates. The first subshaft gear 105 includes a cylindrical bearing portion 105b supported by a shaft 106 protruding substantially vertically from a base portion 110a of the main base 110, a disk portion 105c formed with a worm wheel portion 105a, and a permanent magnet. 8, and a holding portion 105d that holds .

In FIG. 7, the disc portion 105c has a disc shape protruding radially from the outer circumference of the bearing portion 105b. In Embodiment 1, the disk portion 105c is provided at a position closer to the end of the bearing portion 105b farther from the base portion 110a. The holding portion 105d has a cylindrical concave shape provided on the end surface of the disk portion 105c that is farther from the base portion 110a in the axial direction. The bearing portion 105b, the disk portion 105c, and the holding portion 105d are integrally formed so that their central axes are substantially aligned. The first countershaft gear 105 can be made of various materials such as resin material and metal material. In Embodiment 1, the first subshaft gear 105 is made of polyacetal resin.

The worm wheel portion 105a is an example of a second driven gear with which the first worm gear portion 102b meshes. In particular, the worm wheel portion 105a is a gear having 25 teeth formed on the outer circumference of the disk portion 105c. The first worm gear portion 102b and the worm wheel portion 105a constitute a second worm transmission mechanism. The rotation axis of the worm wheel portion 105 a extends in a direction parallel to the axial direction of the motor shaft 201 .

When the number of threads of the first worm gear portion 102b of the first intermediate gear 102 is five and the number of teeth of the worm wheel portion 105a of the first subshaft gear 105 is twenty-five, the reduction ratio is five. That is, when the first intermediate gear 102 rotates five times, the first subshaft gear 105 rotates once. Therefore, when the main shaft gear 101 rotates 100 times, the first intermediate gear 102 rotates 100/20=5, and the first counter shaft gear 105 rotates 5/5=1. Since the first countershaft gear 105 rotates integrally with the permanent magnet 8, the permanent magnet 8 rotates once when the main shaft gear 101 rotates 100 times. That is, the magnetic sensor 50 can identify the amount of rotation of the main shaft gear 101 for 100 rotations.

The absolute encoder 100-1 configured in this way can specify the amount of rotation of the main shaft gear 101. FIG. As an example, when the main shaft gear 101 rotates once, the first counter shaft gear 105 and the permanent magnet 8 rotate 1/100, that is, 3.6 degrees. Therefore, if the rotation angle of the first subshaft gear 105 is 3.6° or less, it can be determined that the rotation amount of the main shaft gear 101 is within one rotation.

In FIG. 5, the second worm gear portion 102h is an example of a third drive gear that drives the worm wheel portion 133a and is also a gear portion of the first intermediate gear 102. As shown in FIG. In particular, the second worm gear portion 102h is a worm gear with one thread number formed on the outer circumference of the third tubular portion 102f. The rotation axis of the second worm gear portion 102h extends in a direction perpendicular to the axial direction of the motor shaft 201. As shown in FIG.

In FIG. 5 , the second intermediate gear 133 is a disc-shaped gear portion that rotates according to the rotation of the motor shaft 201 , decelerates the rotation of the motor shaft 201 and transmits it to the second countershaft gear 138 . The second intermediate gear 133 is provided between the second worm gear portion 102h and the fourth driven gear portion 138a provided on the second countershaft gear 138. As shown in FIG. The fourth driven gear portion 138a meshes with the fourth drive gear portion 133d. The second intermediate gear 133 has a worm wheel portion 133a that meshes with the second worm gear portion 102h of the third drive gear, and a fourth drive gear portion 133d that drives the fourth driven gear portion 138a. The second intermediate gear 133 is made of polyacetal resin, for example. The second intermediate gear 133 is a substantially circular member in plan view. The second intermediate gear 133 includes a bearing portion 133b pivotally supported by the base portion 110a of the main base 110, and an overhang portion 133c formed with a worm wheel portion 133a.

In FIG. 5, by providing the second intermediate gear 133, a second subshaft gear 138, which will be described later, can be arranged at a position away from the second worm gear portion 102h. Therefore, the distance between the permanent magnets 9 and 17 can be lengthened to reduce the mutual influence of leakage magnetic flux. Also, by providing the second intermediate gear 133, the range in which the speed reduction ratio can be set is expanded accordingly, and the degree of freedom in design is improved.

In FIG. 8, the projecting portion 133c has a disk shape projecting radially from the outer circumference of the bearing portion 133b. In Embodiment 1, projecting portion 133c is provided at a position closer to the end of bearing portion 133b farther from base portion 110a of main base 110 . The fourth drive gear portion 133d is formed on the outer periphery of a region closer to the base portion 110a than the projecting portion 133c of the bearing portion 133b. The bearing portion 133b and the projecting portion 133c are integrally formed so that their central axes are substantially aligned.

The worm wheel portion 133a is a gear portion of the second intermediate gear 133 that meshes with the second worm gear portion 102h. In particular, the worm wheel portion 133a is a worm wheel having 30 teeth formed on the outer periphery of the projecting portion 133c. The second worm gear portion 102h and the worm wheel portion 133a constitute a third worm transmission mechanism. The rotation axis of the worm wheel portion 133 a extends in a direction parallel to the axial direction of the motor shaft 201 .

When the number of threads of the second worm gear portion 102h of the first intermediate gear 102 is 1 and the number of teeth of the worm wheel portion 133a of the second intermediate gear 133 is 30, the reduction ratio is 30. That is, when the first intermediate gear 102 rotates 30 times, the second intermediate gear 133 rotates once. Therefore, when the main shaft gear 101 rotates 600 times, the first intermediate gear 102 rotates 600/20=30 times, and the second intermediate gear 133 rotates 30/30=1 time.

The fourth drive gear portion 133d is a transmission element that drives the fourth driven gear portion 138a. The fourth drive gear portion 133d is provided on the opposite side of the main shaft gear 101 from the first counter shaft gear 105 side, and rotates according to the rotation of the worm wheel portion 133a. The fourth drive gear portion 133d is a spur gear having 24 teeth formed on the outer periphery of the bearing portion 133b.

In FIG. 8 , the second subshaft gear 138 is a circular gear portion that rotates in accordance with the rotation of the motor shaft 201 , decelerates the rotation of the motor shaft 201 and transmits it to the permanent magnet 17 . The second countershaft gear 138 is pivotally supported around a rotation axis extending substantially vertically from the base portion 110a of the main base 110 . The second countershaft gear 138 includes a bearing portion 138b that is pivotally supported by the base portion 110a of the main base 110, a protruding portion 138c that forms the fourth driven gear portion 138a, and a magnet holding portion 138d that holds the permanent magnet 17. and including. The bearing portion 138b has a cylindrical shape surrounding the shaft 139 protruding from the base portion 110a of the main base 110 with a gap therebetween.

The protruding portion 138c has a disc shape protruding radially from the outer periphery of the bearing portion 138b. In Embodiment 1, projecting portion 138c is provided at a position near base portion 110a of main base 110 of bearing portion 138b. The magnet holding portion 138d has a cylindrical concave shape provided on the end surface of the bearing portion 138b that is farther from the base portion 110a in the axial direction. The bearing portion 138b, the protruding portion 138c, and the magnet holding portion 138d are integrally formed such that their central axes are substantially aligned. The second countershaft gear 138 can be made of various materials such as resin material and metal material. In Embodiment 1, the second countershaft gear 138 is made of polyacetal resin.

The fourth driven gear portion 138a is a transmission element driven by the fourth drive gear portion 133d. The fourth driven gear portion 138a and the fourth drive gear portion 133d constitute a reduction mechanism. In particular, the fourth driven gear portion 138a is a spur gear having 40 teeth formed on the outer periphery of the projecting portion 138c.

When the number of teeth of the fourth drive gear portion 133d is 24 and the number of teeth of the fourth driven gear portion 138a is 40, the reduction ratio is 40/24=5/3. When the main shaft gear 101 rotates 1000 times, the first intermediate gear 102 rotates 1000/20=50, and the second intermediate gear 133 rotates 50/30=5/3. Therefore, the second subshaft gear 138 rotates by 5/3÷5/3=1 rotation. Since the second countershaft gear 138 rotates integrally with the permanent magnet 17, the permanent magnet 17 rotates once when the main shaft gear 101 rotates 1000 times. That is, the magnetic sensor 90 can identify the amount of rotation of the main shaft gear 101 for 1000 rotations.

5 to 8, permanent magnet 9 is the first permanent magnet, permanent magnet 8 is the second permanent magnet, and permanent magnet 17 is the third permanent magnet. Each of the permanent magnet 8, the permanent magnet 9, and the permanent magnet 17 (hereinafter referred to as each permanent magnet) has a substantially cylindrical shape that is flat in the axial direction. Each permanent magnet is made of a magnetic material such as ferrite, Nd (neodymium)--Fe (iron)--B (boron). Each permanent magnet may be, for example, a rubber magnet containing a resin binder, or a bonded magnet. Each permanent magnet is provided with a magnetic pole. Although the magnetization direction of each permanent magnet is not limited, in Embodiment 1, two magnetic poles are provided on the end surface of each permanent magnet facing the magnetic sensor as shown in FIGS. 41 and 42 . The magnetic flux density distribution in the rotation direction of each permanent magnet may be trapezoidal, sinusoidal, or rectangular.

Each permanent magnet is partly or wholly housed in a recess formed at the end of each rotor, and fixed by, for example, adhesion, caulking, or press-fitting. The permanent magnet 8 is adhesively fixed to the holding portion 105 d of the first countershaft gear 105 . The permanent magnet 9 is adhesively fixed to the magnet holding portion 101 d of the main shaft gear 101 . The permanent magnet 17 is adhesively fixed to the magnet holding portion 138 d of the second countershaft gear 138 .

If the distance between the permanent magnets is short, the detection error of the magnetic sensor will increase due to the influence of the leakage flux of the magnets adjacent to each other. Therefore, in the example of FIG. 5, the permanent magnets 9 and 8 are spaced apart on the line of sight Lm that is inclined with respect to the outer wall portion 115a of the case 115 in plan view. Line of sight Lm is equal to an imaginary line connecting permanent magnets 8 and 9 . Permanent magnets 9 and 17 are spaced apart on line of sight Ln inclined with respect to outer wall portion 115 a of case 115 . Line of sight Ln is equal to an imaginary line connecting permanent magnet 17 and permanent magnet 9 . In the first embodiment, since the lines of sight Lm and Ln are inclined with respect to the outer wall portion 115a, the distance between the permanent magnets is reduced compared to the case where the lines of sight Lm and Ln are parallel to the outer wall portion 115a. can be lengthened.

Each of the magnetic sensor 50, the magnetic sensor 40, and the magnetic sensor 90 (hereinafter referred to as each magnetic sensor) detects an absolute rotation angle in the range of 0° to 360° corresponding to one rotation of each rotating body. sensor. Each magnetic sensor outputs a signal (for example, a digital signal) corresponding to the detected rotation angle to the microcomputer 121 . Each magnetic sensor outputs the same angle of rotation as before the energization is stopped even when the energization is once stopped and then energized again. Therefore, a configuration without a backup power supply is possible.

As shown in FIG. 4, each magnetic sensor is fixed on the same plane on the surface of the substrate 120 on the side of the base portion 110a of the main base 110 by a method such as soldering or adhesion. The magnetic sensor 40 is fixed to the substrate 120 so as to face the end face of the permanent magnet 9 provided on the main shaft gear 101 with a certain gap therebetween. The magnetic sensor 40 is a first angle sensor that detects the rotation angle of the main shaft gear 101 corresponding to changes in magnetic flux generated by the permanent magnet 9 . The magnetic sensor 50 is fixed to the substrate 120 so as to face the end face of the permanent magnet 8 provided on the first countershaft gear 105 with a certain gap therebetween. The magnetic sensor 50 is a second angle sensor that detects the rotation angle of the first subshaft gear 105 corresponding to changes in magnetic flux generated by the permanent magnet 8 . The magnetic sensor 90 is fixed to the substrate 120 so as to face the end face of the permanent magnet 17 provided on the second countershaft gear 138 with a certain gap therebetween. The magnetic sensor 90 is a third angle sensor that detects the rotation angle of the second countershaft gear 138 corresponding to changes in magnetic flux generated by the permanent magnet 17 .

Magnetic angle sensors with relatively high resolution may be used for each magnetic sensor. The magnetic angle sensor is arranged to face the end face including the magnetic poles of each permanent magnet in the axial direction of each rotating body with a certain gap therebetween, and detects the rotation angle of the opposing rotating body based on the rotation of these magnetic poles. Identifies and outputs a digital signal. A magnetic angle sensor includes, for example, a sensing element that senses magnetic poles, and an arithmetic circuit that outputs a digital signal based on the output of the sensing element. The sensing element may include a plurality (eg, four) of magnetic field sensing elements such as Hall elements and GMR (Giant Magneto Resistive) elements.

The arithmetic circuit may identify the rotation angle by table processing using a lookup table, for example, using the difference or ratio of outputs of a plurality of sensing elements as a key. The sensing element and arithmetic circuit may be integrated on one IC chip. This IC chip may be embedded in resin having a thin rectangular parallelepiped outer shape. Each magnetic sensor outputs to the microcomputer 121 an angle signal, which is a digital signal corresponding to the rotation angle of each rotating body detected via a wiring member (not shown). For example, each magnetic sensor outputs the rotation angle of each rotor as a multi-bit (for example, 7-bit) digital signal.

FIG. 9 is a diagram showing a functional configuration of microcomputer 121 included in absolute encoder 100-1 according to Embodiment 1 of the present invention. The microcomputer 121 is fixed to the surface of the substrate 120 on the side of the base portion 110a of the main base 110 by a method such as soldering or bonding. The microcomputer 121 is composed of a CPU, acquires digital signals representing rotation angles output from the magnetic sensors 40 , 50 and 90 and calculates the amount of rotation of the main shaft gear 101 . Each block of the microcomputer 121 shown in FIG. 9 represents a function realized by the CPU as the microcomputer 121 executing a program. Each block of the microcomputer 121 can be implemented by hardware such as a CPU (central processing unit) of a computer and other elements and mechanical devices, and is implemented by computer programs etc. in terms of software. The functional blocks realized by their cooperation are drawn. Therefore, those skilled in the art who have read this specification will understand that these functional blocks can be realized in various ways by combining hardware and software.

The microcomputer 121 includes a rotation angle acquisition section 121p, a rotation angle acquisition section 121q, a rotation angle acquisition section 121r, a table processing section 121b, a rotation amount identification section 121c, and an output section 121e. The rotation angle acquisition unit 121q acquires the rotation angle Aq, which is angle information indicating the rotation angle of the main shaft gear 101, based on the signal output from the magnetic sensor 40. FIG. The rotation angle acquisition unit 121p acquires the rotation angle Ap, which is angle information indicating the rotation angle of the first subshaft gear 105, based on the signal output from the magnetic sensor 50. FIG. The rotation angle acquisition unit 121r acquires the rotation angle Ar, which is angle information indicating the rotation angle of the second countershaft gear 138 detected by the magnetic sensor 90 .

The table processing unit 121b refers to the first correspondence table that stores the rotation angle Ap and the rotation speed of the main shaft gear 101 corresponding to the rotation angle Ap, and rotates the main shaft gear 101 corresponding to the acquired rotation angle Ap. identify the number. Further, the table processing unit 121b refers to the second correspondence table that stores the rotation angle Ar and the number of revolutions of the main shaft gear 101 corresponding to the rotation angle Ar, so that the main shaft gear 101 corresponding to the obtained rotation angle Ar to specify the number of revolutions of

The rotation amount specifying unit 121c specifies a first rotation amount over multiple rotations of the main shaft gear 101 according to the rotational speed of the main shaft gear 101 specified by the table processing unit 121b and the acquired rotation angle Aq. The output unit 121e converts the amount of rotation over multiple rotations of the main shaft gear 101 specified by the rotation amount specifying unit 121c into information indicating the amount of rotation, and outputs the information.

Actions and effects of the absolute encoder 100-1 according to the first embodiment configured as described above will be described.

Absolute encoder 100-1 according to the first embodiment is an absolute encoder that specifies the amount of rotation over a plurality of rotations of motor shaft 201, and includes worm gear portion 101c that rotates according to the rotation of motor shaft 201, worm gear portion 101c, and worm gear portion 101c. A worm wheel portion 102a that meshes, a first worm gear portion 102b that rotates as the worm wheel portion 102a rotates, a worm wheel portion 105a that meshes with the first worm gear portion 102b, and a first countershaft gear that rotates as the worm wheel portion 105a rotates. 105 , a permanent magnet 8 that rotates integrally with the first subshaft gear 105 , and a magnetic sensor 50 that detects the rotation angle of the permanent magnet 8 . According to this configuration, it is possible to specify the amount of rotation over multiple rotations of the motor shaft 201 according to the detection result of the magnetic sensor 50 . A first worm transmission mechanism including a worm gear portion 101c and a worm wheel portion 102a meshing with the worm gear portion 101c, and a second worm transmission mechanism including a first worm gear portion 102b and a worm wheel portion 105a meshing with the first worm gear portion 102b. and , the absolute encoder 100-1 can be made thinner by forming a curved transmission path.

Absolute encoder 100-1 according to the first embodiment is an absolute encoder that specifies the amount of rotation over a plurality of rotations of motor shaft 201, and is a first intermediate encoder that rotates at a first reduction ratio as motor shaft 201 rotates. A gear 102, a first countershaft gear 105 that rotates at a second reduction ratio as the first intermediate gear 102 rotates, a permanent magnet 8 that rotates integrally with the first countershaft gear 105, and a rotation angle of the permanent magnet 8. The rotation axis of the motor shaft 201 is at a twisted position with respect to the rotation axis of the first intermediate gear 102, and is set parallel to the rotation axis of the first countershaft gear 105. ing. According to this configuration, it is possible to specify the amount of rotation over multiple rotations of the motor shaft 201 according to the detection result of the magnetic sensor 50 . Since the rotation axis of the first intermediate gear 102 is at a twisted position with respect to the rotation axes of the motor shaft 201 and the first countershaft gear 105 and is perpendicular to the rotation axis when viewed from the front, the absolute encoder 100-1 forms a curved transmission path. can be made thinner.

Absolute encoder 100-1 according to the first embodiment is an absolute encoder that specifies the amount of rotation over multiple rotations of motor shaft 201, includes a first worm transmission mechanism, and rotates a permanent magnet as motor shaft 201 rotates. 8, and a magnetic sensor 50 for detecting the rotation angle of the permanent magnet 8 according to the magnetic pole of the permanent magnet 8. The rotation axis of the motor shaft 201 is parallel to the rotation axis of the permanent magnet 8. is set. According to this configuration, it is possible to specify the amount of rotation over multiple rotations of the motor shaft 201 according to the detection result of the magnetic sensor 50 . Since the first worm speed change mechanism is included and the rotation axis of the motor shaft 201 and the rotation axis of the permanent magnet 8 are set in parallel, the absolute encoder 100-1 can form a curved transmission path and can be made thinner. .

Absolute encoder 100 - 1 according to the first embodiment includes magnetic sensor 40 that detects the rotation angle of motor shaft 201 . With this configuration, the rotation angle of the motor shaft 201 can be specified according to the detection result of the magnetic sensor 40 . The absolute encoder 100-1 can improve the resolution of the identifiable rotational angle of the motor shaft 201 compared to the case where the magnetic sensor 40 is not provided.

In the absolute encoder 100-1 according to the first embodiment, the second worm gear portion 102h rotates as the worm wheel portion 102a rotates, the worm wheel portion 133a meshes with the second worm gear portion 102h, and the worm wheel portion 133a rotates as the worm wheel portion 133a rotates. , a permanent magnet 17 that rotates integrally with the second countershaft gear 138 , and a magnetic sensor 90 that detects the rotation angle of the permanent magnet 17 . According to this configuration, it is possible to specify the amount of rotation over multiple rotations of the motor shaft 201 according to the detection result of the magnetic sensor 90 . Compared to the case where the magnetic sensor 90 is not provided, the absolute encoder 100-1 can widen the identifiable rotation amount range of the motor shaft 201. FIG.

The absolute encoder 100-1 according to the first embodiment includes the first intermediate gear 102 provided with the first worm gear portion 102b and the second worm gear portion 102h. is set opposite to the direction of the reaction force received by the first intermediate gear 102 due to the rotation of the second worm gear portion 102h. According to this configuration, the combined reaction force of both reaction forces can be made smaller than when the directions of the reaction forces are the same.

In absolute encoder 100-1 according to the first embodiment, the outer diameter of worm wheel portion 102a is set smaller than the outer diameter of worm gear portion 101c. With this configuration, it is easier to reduce the thickness of the worm wheel portion 102a than when the outer diameter of the worm wheel portion 102a is large.

Here, for example, when the main shaft gear 101 and the first counter shaft gear 105 are arranged adjacent to each other, part of the magnetic flux generated by each of the permanent magnets 8 and 9 is transferred to the permanent magnets 8 and 9 . We describe the so-called magnetic interference that affects magnetic sensors that are not compliant with each other.

FIG. 34 shows the waveform (A) of the magnetic flux of the permanent magnet 9 provided on the main shaft gear 101 (main shaft gear 1) detected by the magnetic sensor 40, and the waveform (A) provided on the first sub shaft gear 105 (sub shaft gear 5). A waveform (B) of the magnetic flux of the permanent magnet 8 detected by the magnetic sensor 50 and a magnetic interference waveform ( It is a figure showing the concept of C). The vertical axis represents the magnetic flux, and the horizontal axis represents the rotation angle of the main shaft gear 101 . Thus, in the magnetic sensor 40, although it is desirable to detect the waveform of (A), when magnetic interference occurs, the waveform becomes as shown in (C), and an accurate waveform cannot be detected. Gone.

Similarly, FIG. 35 shows a waveform (A) of the magnetic flux of the permanent magnet 8 provided on the first countershaft gear 105 (countershaft gear 5) detected by the magnetic sensor 50, and the main shaft gear 101 (mainshaft gear 1). A waveform (B) obtained by detecting the magnetic flux of the provided permanent magnet 9 by the magnetic sensor 40, and a magnetic sensor 50 detecting a state in which a part of the magnetic flux of the permanent magnet 9 is superimposed on the magnetic flux of the permanent magnet 8 as leakage magnetic flux. It is a figure showing the concept with an interference waveform (C). The vertical axis represents the magnetic flux, and the horizontal axis represents the rotation angle of the first countershaft gear 105 . Thus, in the magnetic sensor 50, although it is desirable to detect the waveform of (A), when magnetic interference occurs, the waveform becomes as shown in (C), and an accurate waveform cannot be detected. Gone. Further, magnetic interference may occur between the main shaft gear 101 and the second counter shaft gear 138 as in FIG. 35(C).

Absolute encoder 100-1 according to Embodiment 1 includes case 115 including outer wall portion 115a arranged on the opposite side of motor shaft 201 of first intermediate gear 102, and in plan view, the first intermediate gear 102 The rotation axis La is inclined at 20° with respect to the extending direction of the outer wall portion 115a. According to this configuration, compared to the case where the rotation axis La of the first intermediate gear 102 is not inclined, it is possible to increase the inclination of the arrangement straight line of each permanent magnet with respect to the outer wall portion 115a. Therefore, the distance between each permanent magnet can be increased. In this way, by increasing the distance between the respective permanent magnets, part of the magnetic flux generated by each of the permanent magnets 8, 9 and 17 is transferred to the permanent magnets 8, 9 and 17. It is possible to reduce the occurrence of magnetic interference that affects magnetic sensors that are not compatible with each of the above. For example, the magnetic sensor 50 provided for the original purpose of detecting a change in the magnetic flux generated by the permanent magnet 8 provided on the first countershaft gear 105 may generate a magnetic flux generated by the permanent magnet 9 provided on the main shaft gear 101 . A part of the generated magnetic flux can reduce interference as leakage magnetic flux. Also, part of the magnetic flux generated by the permanent magnet 8 provided on the first counter shaft gear 105 leaks to the magnetic sensor 40 provided for the original purpose of detecting changes in the magnetic flux generated by the permanent magnet 9. Interference as magnetic flux can be reduced. Therefore, it is possible to reduce the influence of the leakage magnetic flux of the adjacent magnets.

FIG. 10 is a diagram showing a first modification of absolute encoder 100-1 according to Embodiment 1 of the present invention. FIG. 11 is a perspective view of the magnetic flux shield 500 shown in FIG. FIG. 12 is a vertical cross-sectional view of the magnetic flux shielding portion 500 shown in FIG. FIG. 11 shows magnetic flux shielding portion 500 provided in absolute encoder 100-1 according to the first modification of the first embodiment. The distance from the magnetic sensor 40 to the magnetic sensor 50 and the distance from the magnetic sensor 40 to the magnetic sensor 90 tend to become relatively shorter as the dimension of the absolute encoder 100-1 in the direction orthogonal to the Z-axis direction becomes smaller. There is When the distance between adjacent permanent magnets is shortened in this way, the above-described magnetic interference is likely to occur.

On the other hand, the absolute encoder 100-1 according to the first embodiment uses the first intermediate gear 102 to obtain a small size and a large reduction ratio. , the dimension of the absolute encoder 100-1 in the Z-axis direction becomes smaller. Therefore, the distance in the Z-axis direction from the magnetic sensor 40 to the motor 200 is relatively short, and the magnetic flux leaking from the motor 200 may adversely affect the magnetic sensor 40, the magnetic sensor 50, the magnetic sensor 90, and the like. be. Absolute encoder 100-1 according to the first modification of the first embodiment is constructed in view of such problems, and base 110a of main base 110 is constructed of a magnetic material that functions as a magnetic shield. there is

The magnetic flux shielding portion 500 is a first magnetic flux shielding portion provided at a position facing the worm gear portion 101c. The magnetic flux shielding portion 500 includes a first plate surface 500a facing the worm gear portion 101c and a second plate surface 500b opposite to the first plate surface 500a side of the magnetic flux shielding portion 500. As shown in FIG. The magnetic flux shielding portion 500 has a first end surface 500c facing the worm wheel portion 133a, a second end surface 500d facing the first intermediate gear 102, and a third end surface 500e facing the lower surface 120-1 of the substrate 120 shown in FIG. Prepare.

The magnetic flux shielding portion 500 is an arc-shaped plate member extending from the base portion 110a of the main base 110 in the positive direction of the Z axis. Each of the first plate surface 500a and the second plate surface 500b is curved in a projecting shape in the direction from the first plate surface 500a to the second plate surface 500b. For example, the magnetic flux shielding portion 500 is provided on the base portion 110a of the main base 110 so that the imaginary line extending in the Z-axis positive direction of the wall surface 110-1a forming the opening portion 110-1 passes over the first plate surface 500a. . The magnetic flux shielding part 500 is a member made of iron, for example.

Note that magnetic flux shielding portion 500 is not limited to being manufactured separately from base portion 110a of main base 110, and absolute encoder 100-1 according to the first modification of Embodiment 1 can be formed by pressing, forging, or casting. It may be configured by the base portion 110a of the main base 110 and the magnetic flux shielding portion 500 which are integrally molded with or lost wax. Moreover, the material of the magnetic flux shielding part 500 is not limited to iron as long as it can shield the magnetic flux generated from each of the plurality of permanent magnets. However, when the magnetic flux shielding portion 500 is integrally molded with the base portion 110a of the main base 110, the magnetic flux shielding portion 500 is more difficult than when the base portion 110a of the main base 110 and the magnetic flux shielding portion 500 are separately manufactured. In some cases, the accuracy of the position and dimensions of such as is improved.

The first plate surface 500a of the magnetic flux shielding portion 500 is provided at a position spaced apart from the worm gear portion 101c by a certain distance so as not to interfere with the worm gear portion 101c. Also, the first end surface 500c of the magnetic flux shielding portion 500 is provided at a certain distance from the worm wheel portion 133a so as not to interfere with the worm wheel portion 133a. A portion of the magnetic flux shielding portion 500 close to the first end surface 500c is arranged between the permanent magnet 17 and the magnetic sensor 40 or between the permanent magnet 17 and the magnetic sensor 90 so as to block the line of sight Ln between the permanent magnet 17 and the magnetic sensor 40 or between the permanent magnet 9 and the magnetic sensor 90. 40 or provided between the permanent magnet 9 and the magnetic sensor 90 . As a result, part of the magnetic flux generated by the permanent magnet 17 can be reduced from flowing into the magnetic sensors 40 and 50 as leakage magnetic flux. In addition, it is possible to reduce the flow of part of the magnetic flux generated by the permanent magnet 9 into the magnetic sensor 90 as leakage magnetic flux.

The second plate surface 500b of the magnetic flux shielding portion 500 is provided at a position a certain distance away from the fourth driven gear portion 138a so that the portion near the first end surface 500c does not interfere with the fourth driven gear portion 138a. ing.

A second end surface 500d of the magnetic flux shielding portion 500 is provided at a position spaced apart from the first intermediate gear 102 by a certain distance so as not to interfere with the first intermediate gear 102 . A portion of the magnetic flux shielding portion 500 closer to the second end surface 500d is arranged so as to block the line of sight Lm between the permanent magnet 8 and the magnetic sensor 40 or between the permanent magnet 8 and the magnetic sensor 50. 40 is provided between the permanent magnet 9 and the magnetic sensor 50 . As a result, part of the magnetic flux generated by the permanent magnet 8 can be reduced from flowing into the magnetic sensor 40 and the magnetic sensor 90 as leakage magnetic flux. In addition, it is possible to reduce the flow of part of the magnetic flux generated by the permanent magnet 9 into the magnetic sensor 50 as leakage magnetic flux.

The height of the magnetic flux shielding portion 500 in the Z-axis direction is equal to the width in the Z-axis direction from the third end surface 500e of the magnetic flux shielding portion 500 to the base portion 110a of the main base 110 . As shown in FIG. 12, the position of the third end surface 500e of the magnetic flux shielding portion 500 may be provided above the position of the upper surface 9a of the permanent magnet 9 in the Z-axis positive direction. For example, the third end face 500e of the magnetic flux shielding portion 500 may be provided so as to contact the lower surface 120-1 of the substrate 120. FIG.

By providing the magnetic flux shielding portion 500 in this manner, it is possible to reduce the flow of part of the magnetic flux generated by the permanent magnet 9 into the magnetic sensors 50 and 90 as leakage magnetic flux. Further, by providing the magnetic flux shielding part 500, it is possible to reduce the flow of part of the magnetic flux generated by the permanent magnet 8 as leakage flux into the magnetic sensor 40, and part of the magnetic flux generated by the permanent magnet 17 as leakage flux. , flow into the magnetic sensor 40 can be reduced.

Furthermore, by providing the magnetic flux shielding portion 500, even if the magnetic flux generated by the motor 200 reaches the magnetic sensor 40 through the opening 110-1, it becomes difficult for the magnetic flux to reach the magnetic sensors 50 and 90.

As a result, in the absolute encoder 100-1 according to the first modification of the first embodiment, the rotation angle or the rotation angle of the first countershaft gear 105 by the magnetic sensor 50 is greater than when the magnetic flux shielding portion 500 is not provided. It is possible to reduce the decrease in the detection accuracy of the amount. In addition, deterioration in detection accuracy of the rotation angle or rotation amount of the main shaft gear 101 by the magnetic sensor 40 can be reduced, and deterioration in detection accuracy of the rotation angle or rotation amount of the second counter shaft gear 138 by the magnetic sensor 90 can be reduced.

As the absolute encoder 100-1 is miniaturized, the influence of leakage magnetic flux increases. Therefore, in order to miniaturize the absolute encoder 100-1, it is desirable to provide the magnetic flux shielding portion 500 at the base portion 110a of the main base 110. .

FIG. 13 is a plan view showing a second modification of absolute encoder 100-1 according to Embodiment 1 of the present invention. FIG. 14 is a perspective view of magnetic flux shielding portion 501 and magnetic flux shielding portion 502 shown in FIG. FIG. 15 is a vertical cross-sectional view of the magnetic flux shield 502 shown in FIG.

Each of the magnetic flux shielding portion 501 and the magnetic flux shielding portion 502 is an arc-shaped plate-like member obtained by omitting a portion of the magnetic flux shielding portion 500 shown in FIG. Each of the magnetic flux shielding portion 501 and the magnetic flux shielding portion 502 extends in the Z-axis positive direction from the base portion 110a of the main base 110 and functions as a magnetic shield, similarly to the magnetic flux shielding portion 500 shown in FIG.

The magnetic flux shielding portion 501 is provided at a position facing the worm gear portion 101 c and is a third magnetic flux shielding portion that shields magnetic flux generated from at least one of the permanent magnets 17 and 9 . The magnetic flux shielding part 501 is provided on the base part 110a of the main base 110 so as to block the line of sight Ln between the permanent magnet 17 and the magnetic sensor 40 or between the permanent magnet 9 and the magnetic sensor 90 . The magnetic flux shielding portion 502 is provided at a position facing the worm gear portion 101 c and is a second magnetic flux shielding portion that shields magnetic flux generated from at least one of the permanent magnets 8 and 9 . The magnetic flux shielding part 502 is provided on the base part 110a of the main base 110 so as to block the line of sight Lm between the permanent magnet 8 and the magnetic sensor 40 or between the permanent magnet 9 and the magnetic sensor 50. FIG. It should be noted that the magnetic flux shielding portion 501 is not limited to being molded separately from the base portion 110a of the main base 110, and the absolute encoder 100-1 according to the second modification of the first embodiment can be formed by pressing, forging, or casting. It may be configured by the base portion 110a of the main base 110 and the magnetic flux shielding portion 501, which are integrally molded with , lost wax, or the like. The magnetic flux shielding part 502 is also the same.

The height of the magnetic flux shielding portion 501 in the Z-axis direction is equal to the width in the Z-axis direction from the front end surface 501a of the magnetic flux shielding portion 501 in the positive Z-axis direction to the base portion 110a of the main base 110 . The position of the tip surface 501a of the magnetic flux shielding portion 501 may be provided above the position of the upper surface 9a of the permanent magnet 9 in the Z-axis positive direction. For example, the tip surface 501a of the magnetic flux shielding portion 501 may be provided so as to contact the bottom surface 120-1 of the substrate 120. FIG. By setting the position of the front end face 501a of the magnetic flux shielding portion 501 in the positive direction of the Z-axis in this manner, it is possible to reduce the flow of part of the magnetic flux generated by the permanent magnet 9 into the magnetic sensor 90 as leakage magnetic flux. Also, by providing the magnetic flux shielding portion 501, it is possible to reduce the flow of part of the magnetic flux generated by the permanent magnet 17 into the magnetic sensor 40 as leakage magnetic flux. Further, by providing the magnetic flux shielding portion 501, even if the magnetic flux generated by the motor 200 reaches the magnetic sensor 40 through the opening 110-1, it becomes difficult for the magnetic flux to reach the magnetic sensor 90. FIG.

The height of the magnetic flux shielding portion 502 in the Z-axis direction is equal to the width in the Z-axis direction from the front end surface 502a of the magnetic flux shielding portion 502 in the positive Z-axis direction to the base portion 110a of the main base 110 . As shown in FIG. 15, the position of the tip surface 502a of the magnetic flux shielding portion 502 may be provided above the position of the upper surface 9a, which is the tip of the permanent magnet 9, in the positive Z-axis direction. For example, the tip surface 502a of the magnetic flux shielding portion 502 may be provided so as to contact the bottom surface 120-1 of the substrate 120. FIG. By setting the position of the tip surface 502a in this way, it is possible to reduce the flow of part of the magnetic flux generated by the permanent magnet 9 into the magnetic sensor 50 as leakage magnetic flux. Further, by providing the magnetic flux shielding portion 502, it is possible to reduce the flow of part of the magnetic flux generated by the permanent magnet 8 into the magnetic sensor 40 as leakage magnetic flux. Further, by providing the magnetic flux shielding portion 502, even if the magnetic flux generated by the motor 200 reaches the magnetic sensor 40 through the opening 110-1, it becomes difficult for the magnetic flux to reach the magnetic sensor 50. FIG.

As a result, in the absolute encoder 100-1 according to the second modification of the first embodiment, as compared with the case where the magnetic flux shielding portion 501 and the magnetic flux shielding portion 502 are not provided, It is possible to reduce the decrease in detection accuracy of the rotation angle or amount of rotation. In addition, deterioration in the detection accuracy of the rotation angle or rotation amount of the main shaft gear 101 by the magnetic sensor 40 can be reduced. Furthermore, in the absolute encoder 100-1 according to the second modification of the first embodiment, it is possible to reduce the decrease in the detection accuracy of the rotation angle or rotation amount of the second subshaft gear 138 by the magnetic sensor 90. FIG.

Absolute encoder 100-1 according to the second modification of Embodiment 1 includes magnetic flux shielding portion 501 and magnetic flux shielding portion 502, but may be configured to include magnetic flux shielding portion 501 or magnetic flux shielding portion 502. good. Even in such a configuration, the magnetic sensor 40, the magnetic sensor 50, the magnetic sensor 90, etc. are more effective than the case where the base portion 110a of the main base 110 is not provided with either the magnetic flux shielding portion 501 or the magnetic flux shielding portion 502. It is possible to reduce the decrease in the detection accuracy of the rotation angle or rotation amount due to. However, the smaller the absolute encoder 100-1, the greater the influence of leakage magnetic flux. Preferably, it is provided at the base portion 110a of 110 .

The magnetic flux shielding portion 501 and the magnetic flux shielding portion 502 are made of the same magnetic material as the magnetic flux shielding portion 500 described above. However, when the magnetic flux shielding portion 501 and the magnetic flux shielding portion 502 are integrally formed with the base portion 110a of the main base 110, the base portion 110a of the main base 110, the magnetic flux shielding portion 501, and the magnetic flux shielding portion 502 are manufactured separately. In some cases, the accuracy of the positions and dimensions of the magnetic flux shielding portion 501 and the magnetic flux shielding portion 502 is improved compared to the case where the magnetic flux shielding portion 502 is provided.

Further, in the absolute encoder 100-1 according to the modification of the first embodiment, a magnetic material such as iron is provided between the second angle sensor and the motor 200 or between the third angle sensor and the motor 200. A base portion 110a of a main base 110, which is a plate-like member, is provided. That is, the base portion 110 a functions as a magnetic shield against magnetic flux leaking from the motor 200 . Therefore, it becomes difficult for the magnetic flux leaking from the motor 200 to reach the magnetic sensor 40 or the like. As a result, compared with the case where the base portion 110a is made of a non-magnetic material such as aluminum having a low magnetic permeability, it is possible to reduce the decrease in accuracy in detecting the rotation angle or rotation amount of the gear by the magnetic sensor.

<Embodiment 2>
FIG. 16 is a perspective view showing a state where absolute encoder 100-2 according to Embodiment 2 of the present invention is attached to motor 200. FIG. Hereinafter, as in the first embodiment, the description will be made based on the XYZ orthogonal coordinate system. The X-axis direction corresponds to the horizontal left-right direction, the Y-axis direction corresponds to the horizontal front-back direction, and the Z-axis direction corresponds to the vertical up-down direction. The Y-axis direction and the Z-axis direction are orthogonal to the X-axis direction. The X-axis direction may be referred to as the leftward or rightward direction, the Y-axis direction as the forward direction or the rearward direction, and the Z-axis direction as the upward direction or downward direction. In FIG. 16, a state viewed from above in the Z-axis direction is called a plan view, a state viewed from the front in the Y-axis direction is called a front view, and a state viewed from the left and right in the X-axis direction is called a side view. Such directional notation does not limit the use posture of the absolute encoder 100-2, and the absolute encoder 100-2 can be used in any posture. FIG. 16 transparently shows the parts provided inside the case 15 of the absolute encoder 100-2. Note that the shape of the tooth portion is omitted in the drawings.

FIG. 17 is a perspective view showing a state in which the case 15 and mounting screws 16 are removed from the absolute encoder 100-2 shown in FIG. 17 transparently shows a plurality of components provided on the lower surface 20-1 of the substrate 20. FIG. FIG. 18 is a perspective view showing a state in which the board 20 and the board mounting screws 13 are removed from the absolute encoder 100-2 shown in FIG. FIG. 19 is a perspective view showing a state in which the motor 200 and the screw 14 are removed from the perspective view in which the absolute encoder 100-2 shown in FIG. 18 is attached to the motor 200. FIG. 20 is a plan view of the main base 10, the intermediate gear 2, etc. shown in FIG. 19. FIG. FIG. 20 shows the arrangement of main parts among the plurality of parts included in absolute encoder 100-2. FIG. 21 is a cross-sectional view of the absolute encoder 100-2 shown in FIG. 20 taken along a plane passing through the center of the intermediate gear 2 and parallel to the XY plane.

22 is an enlarged partial cross-sectional view showing a state in which the bearing 3 shown in FIG. 21 is removed from the intermediate gear 2. FIG. In FIG. 22 , the bearing 3 is separated from the press-fit portion 2 d of the intermediate gear 2 in order to facilitate understanding of the arrangement relationship between the bearing 3 and the press-fit portion 2 d formed in the intermediate gear 2 . Further, in FIG. 22, the bearing 3 is separated from the wall portion 80 in order to facilitate understanding of the arrangement relationship between the bearing 3 and the wall portion 80 provided on the base portion 60 of the main base 10 .

23 is a cross-sectional view of the absolute encoder 100-2 shown in FIG. 17 taken along a plane passing through the center of the main shaft gear 1 shown in FIG. 20 and perpendicular to the center line of the intermediate gear 2. FIG. However, the substrate 20 and the magnetic sensor 40 are not sectioned. FIG. 23 shows how the permanent magnet 9 is attached to the main shaft gear 1 and how the main shaft gear 1 is attached to the motor shaft 201 . 23 shows a state in which the worm gear portion 1d of the main shaft gear 1 and the worm wheel portion 2a of the intermediate gear 2 are in mesh. According to FIG. 23, it can be seen that the upper surface 9a of the permanent magnet 9 provided on the main shaft gear 1 is located at a certain distance from the magnetic sensor 40 in the Z-axis direction.

24 is a cross-sectional view of the absolute encoder 100-2 shown in FIG. 17 taken along a plane that passes through the center of the countershaft gear 5 shown in FIG. 21 and is perpendicular to the centerline of the intermediate gear 2. FIG. However, the substrate 20 and the magnetic sensor 50 are not sectioned. FIG. 24 shows a state in which the worm wheel portion 5a and the worm gear portion 2b are engaged with each other. 24 shows a state in which the shaft portion 6b of the magnet holder 6 is held by two bearings 7 and a state in which the permanent magnet 8 is held by the magnet holder 6. As shown in FIG. FIG. 24 also shows a state in which the radially outer surface of the head 6c provided on the magnet holder 6 is separated from the addendum circle of the worm gear portion 2b. Further, according to FIG. 24, it can be seen that the surface 8a of the permanent magnet 8 provided in the magnet holder 6 is located at a certain distance from the magnetic sensor 50 in the Z-axis direction. 24 shows the cross-sectional shape of the bearing holder portion 10d of the main base 10. As shown in FIG.

25 is a perspective view showing a state in which the intermediate gear 2 is removed from among the multiple parts shown in FIG. 18. FIG. 26 shows a state where the screw 12 is removed from the wall portion 70 shown in FIG. 25, a state of the plate spring 11 after the screw 12 is removed, and a plate spring mounting surface 10e facing the plate spring 11. 3 is a perspective view showing a wall portion 70 with a side wall portion. FIG. However, the motor 200 and the main shaft gear 1 are not shown.

27 is a cross-sectional view of the absolute encoder 100-2 shown in FIG. 17 taken along a plane parallel to the Z-axis direction passing through the center of the substrate positioning pin 10g and the center of the substrate positioning pin 10j shown in FIG. is. However, the magnetic sensor 40 is not sectioned.

FIG. 28 is a view of the substrate 20 shown in FIG. 17 viewed from the lower surface 20-1 side. FIG. 29 is a view of the state of FIG. 16 with the motor 200 removed and viewed from the lower surface 10-2 side of the main base 10. FIG. The lower surface 10-2 of the main base 10 is the surface opposite to the upper surface of the main base 10 shown in FIG. The lower surface 10 - 2 of the main base 10 is also the surface facing the motor 200 . 30 is a perspective view of the case 15 shown in FIG. 16. FIG.

31 is a cross-sectional view of the absolute encoder 100-2 shown in FIG. 16 taken along a plane parallel to the Z-axis direction passing through the center of the substrate positioning pin 10g and the center of the substrate positioning pin 10j shown in FIG. be. However, the motor 200, the main shaft gear 1, and the magnetic sensor 40 are not cross-sectioned. In FIG. 31, the claw 15a provided on the case 15 is engaged with the concave portion 10aa provided on the main base 10, and the claw 15b provided on the case 15 is engaged with the concave portion 10ab provided on the main base 10. Multiplied states are shown. 32 is an exploded perspective view of the permanent magnet 8, magnet holder 6, countershaft gear 5 and bearing 7 shown in FIG. 33 is an exploded perspective view of the permanent magnet 9, main shaft gear 1 and motor shaft 201 shown in FIG.

The configuration of the absolute encoder 100-2 will be described in detail below with reference to FIGS. 16 to 33. FIG. The absolute encoder 100-2 includes a main shaft gear 1, an intermediate gear 2, a bearing 3, a shaft 4, a sub shaft gear 5, a magnet holder 6, a bearing 7, a permanent magnet 8, a permanent magnet 9, a main base 10, a leaf spring 11, a screw 12 , board mounting screws 13 and 14 , case 15 , mounting screws 16 , board 20 , microcomputer 21 , bidirectional driver 22 , line driver 23 , connector 24 , magnetic sensor 40 and magnetic sensor 50 .

Motor 200 is, for example, a stepping motor, a DC brushless motor, or the like. The motor 200 is used, for example, as a driving source for driving an industrial robot through a reduction mechanism such as a strain wave gearing. The motor 200 has a motor shaft 201 . As shown in FIG. 23, one end of the motor shaft 201 protrudes from the housing 202 of the motor 200 in the Z-axis positive direction. Further, as shown in FIG. 16, the other end of the motor shaft 201 protrudes from the housing 202 of the motor 200 in the Z-axis negative direction. Also, the motor shaft 201 is an example of a main shaft.

The outer shape of the motor 200 in plan view is, for example, square. The length of each of the four sides forming the outer shape of the motor 200 is, for example, 25 mm. Of the four sides forming the outer shape of motor 200, the first side and the second side parallel to the first side are parallel to the Y-axis. Further, among the four sides, the third side adjacent to the first side and the fourth side parallel to the third side are parallel to the X axis. The absolute encoder 100-2 provided in the motor 200 is 25 mm square in conformity with the outer shape of the motor 200 which is 25 mm square in plan view.

Next, each of the plurality of components included in absolute encoder 100-2 will be described.

As shown in FIG. 23 , the main shaft gear 1 is a cylindrical member provided coaxially with the motor shaft 201 . The main shaft gear 1 includes a tubular first tubular portion 1a, and a tubular second tubular portion 1b provided coaxially with the first tubular portion 1a on the Z-axis positive direction side of the first tubular portion 1a. Prepare. In addition, the main shaft gear 1 includes a communicating portion 1c that connects the first tubular portion 1a and the second tubular portion 1b provided radially inside the second tubular portion 1b, and a communicating portion 1c that is provided radially outwardly of the second tubular portion 1b. and a worm gear portion 1d provided. By forming the communicating portion 1 c in this way, the communicating portion 1 c functions as an escape route for air when the main shaft gear 1 is press-fitted onto the motor shaft 201 . The inner diameter of the communicating portion 1c is smaller than the inner diameter of the first cylindrical portion 1a and the inner diameter of the second cylindrical portion 1b. The space surrounded by the bottom surface 1e, which is the end surface of the communicating portion 1c in the Z-axis negative direction, and the inner peripheral surface of the first cylindrical portion 1a is a press-fitting portion for fixing the main shaft gear 1 to the end portion of the motor shaft 201. 1f. The press-fit portion 1f is a recess that is recessed from the end of the first tubular portion 1a on the negative Z-axis direction toward the positive Z-axis direction. A motor shaft 201 is press-fitted into the press-fit portion 1f, and the main shaft gear 1 rotates integrally with the motor shaft 201. As shown in FIG. The worm gear portion 1 d is a gear portion of the main shaft gear 1 .

A space surrounded by the bottom surface 1g, which is the end surface of the communicating portion 1c in the positive direction of the Z-axis, and the inner peripheral surface of the second tubular portion 1b is a magnet holding portion 1h for fixing the permanent magnet 9 therein. The magnet holding portion 1h is a recess that is recessed from the end of the second cylindrical portion 1b on the Z-axis positive direction side toward the Z-axis negative direction side. A permanent magnet 9 is press-fitted into the magnet holding portion 1h. The permanent magnet 9 press-fitted into the magnet holding portion 1h has an outer peripheral surface in contact with the inner peripheral surface of the second cylindrical portion 1b and a lower surface 9b in contact with the bottom surface 1g. As a result, the permanent magnet 9 is positioned in the axial direction and in the direction orthogonal to the axial direction. The axial direction of the permanent magnet 9 is the same as the central axial direction of the motor shaft 201 .

As shown in FIGS. 19 to 21 and 23 , the worm gear portion 1 d is composed of helically formed teeth and meshes with the worm wheel portion 2 a of the intermediate gear 2 . The worm wheel portion 2 a is a gear portion of the intermediate gear 2 . Illustration of the shape of the tooth portion is omitted in FIG. The worm gear portion 1d is made of, for example, polyacetal resin. The worm gear portion 1d is an example of a first drive gear.

As shown in FIGS. 19 to 22 and the like, the intermediate gear 2 is supported by the shaft 4 on the upper surface of the main base 10 . The central axis of intermediate gear 2 is parallel to the XY plane. Also, the central axis of the intermediate gear 2 is not parallel to each of the X-axis and the Y-axis in plan view. That is, the central axis direction of the intermediate gear 2 is oblique to the directions in which the X-axis and the Y-axis extend. That the direction of the central axis of the intermediate gear 2 is oblique to the directions in which the X-axis and the Y-axis respectively extend means that the central axis of the intermediate gear 2 extends obliquely to the four sides of the main base 10. means. As shown in FIGS. 19 and 20, the four sides of the main base 10 are a first side 301 parallel to the YZ plane, a second side 302 parallel to the first side 301, and a second side 302 parallel to the XZ plane. It is composed of a third side 303 adjacent to the first side 301 and a fourth side 304 parallel to the third side 303 . The first side 301 is a side provided on the X-axis positive direction side of the main base 10 . The second side 302 is a side provided on the X-axis negative direction side of the main base 10 . The third side 303 is a side provided on the Y-axis positive direction side of the main base 10 . A fourth side 304 is a side provided on the Y-axis negative direction side of the main base 10 .

The dimensions of the absolute encoder 100-2 in a plan view are, for example, matched to the dimensions of the motor 200, which is 25 mm square. Therefore, the intermediate gear 2 arranged parallel to the XY plane is provided so as to extend obliquely with respect to the four sides of the main base 10, thereby reducing the dimension of the absolute encoder 100-2 in the horizontal direction. be able to. The horizontal direction is equal to the direction orthogonal to the center axis of the motor shaft 201 and equal to the direction parallel to the XY plane.

As shown in FIGS. 18 to 22 and the like, the intermediate gear 2 has a worm wheel portion 2a, a worm gear portion 2b, a bearing portion 2c, a press-fitting portion 2d, a sliding portion 2e, a bottom surface 2f, and a through hole 2g. The intermediate gear 2 is a cylindrical member in which a shaft 4 is inserted through a through hole 2g extending along the central axis. The through hole 2 g is a space surrounded by the inner peripheral surface of the intermediate gear 2 . The intermediate gear 2 is a member integrally molded of metal, resin, or the like, and is formed of polyacetal resin as an example here.

The worm wheel portion 2a is a gear with which the worm gear portion 1d of the main shaft gear 1 meshes. The worm wheel portion 2 a is an example of a first driven gear and is a gear portion of the intermediate gear 2 . The worm wheel portion 2 a is provided at a location near the center of the intermediate gear 2 in the axial direction of the intermediate gear 2 . The worm wheel portion 2 a is composed of a plurality of teeth provided on the outer peripheral portion of the cylindrical portion of the intermediate gear 2 .

The outer diameter of the worm wheel portion 2a is smaller than the outer diameter of the worm gear portion 1d. Since the central axis of the worm wheel portion 2a is parallel to the upper surface of the main base 10, the outer diameter of the worm wheel portion 2a is reduced, thereby miniaturizing the absolute encoder 100-2 in the Z-axis direction (height direction). is possible.

The worm gear portion 2b is composed of spirally formed teeth, and is coaxially adjacent to the worm wheel portion 2a. The worm gear portion 2 b is provided on the outer peripheral portion of the cylindrical portion of the intermediate gear 2 . The rotational force of the intermediate gear 2 is transmitted to the subshaft gear 5 by the worm gear portion 2b meshing with the worm wheel portion 5a provided on the subshaft gear 5 . The worm gear portion 2b is an example of a second driving gear and also a gear portion of the intermediate gear 2. As shown in FIG. The worm wheel portion 5 a is a gear portion of the countershaft gear 5 . The center line of the worm wheel portion 5a and the center line of the worm gear portion 2b are perpendicular to each other when viewed from a direction perpendicular to the center line of the worm wheel portion 5a and perpendicular to the center line of the worm gear portion 2b.

The outer diameter of the worm gear portion 2b is set to a value as small as possible in order to reduce the size of the absolute encoder 100-2 in the Z-axis direction (height direction).

As shown in FIG. 21, the bearing portion 2c is provided on the radially inner inner peripheral surface of the intermediate gear 2 on the side opposite to the press-fitting portion 2d side of the intermediate gear 2, that is, on the sliding portion 2e side of the intermediate gear 2. It is A shaft 4 is slidably inserted through the bearing portion 2c, and the intermediate gear 2 is rotatably supported by the shaft 4. As shown in FIG.

The press-fit portion 2d is a recess that is recessed from the end surface of the intermediate gear 2 toward the center of the intermediate gear 2 in the axial direction Td inside the worm gear portion 2b, and communicates with the through hole 2g. The press-fit portion 2d can also be interpreted as a portion in which the opening diameter of the end portion of the through hole 2g is increased. The outer ring 3a of the bearing 3 is press-fitted and fixed in the press-fit portion 2d.

As shown in FIGS. 19 to 21, 25, 26, etc., the sliding portion 2e of the intermediate gear 2 is located on one end side of the intermediate gear 2, that is, opposite to the worm gear portion 2b side in the axial direction Td of the intermediate gear 2. provided on the side. A sliding portion 2 e of the intermediate gear 2 contacts a sliding portion 11 a of the plate spring 11 . The leaf spring 11 is an example of an elastic member, and is made of metal, for example. The sliding portion 11a of the leaf spring 11 is composed of two branched bodies bifurcated from the base portion 11d of the leaf spring 11 . The base portion 11 d of the leaf spring 11 is a plate-like member provided between the mounting portion 11 b and the sliding portion 11 a in the entire leaf spring 11 .

A gap larger than the diameter of the shaft 4 is formed between the two branches forming the sliding portion 11 a of the leaf spring 11 . Therefore, the two branches straddle the shaft 4, and the mounting portion 11b of the plate spring 11 is attached to the plate spring mounting surface 10e provided on the wall portion 72 of the main base 10 by the screws 12 so as not to come into contact with the shaft 4. Fixed.

The sliding portion 11a of the leaf spring 11 is provided at a position facing the sliding portion 2e of the intermediate gear 2 after the intermediate gear 2 is assembled. The sliding portion 2e of the intermediate gear 2 contacts and is pressed against the sliding portion 11a of the plate spring 11, thereby moving along the central axis of the shaft 4 from one end 4a side of the shaft 4 to the other end 4b side of the shaft 4. is biased in a direction toward When the intermediate gear 2 rotates in this state, the sliding portion 2e of the intermediate gear 2 slides in contact with the sliding portion 11a of the plate spring 11. As shown in FIG.

A bottom surface 2f of the intermediate gear 2 is positioned next to the press-fit portion 2d and contacts a side surface 3c of the outer ring 3a of the bearing 3. As shown in FIG. The outer ring 3a is press-fitted into the press-fit portion 2d until the side surface 3c of the outer ring 3a contacts the bottom surface 2f.

The through hole 2g of the intermediate gear 2 penetrates along the central axis of the intermediate gear 2 from the bearing portion 2c toward the press-fitting portion 2d, and is arranged coaxially with the shaft 4. As shown in FIG. Since the inner diameter of the through hole 2 g is larger than the outer diameter of the shaft 4 , a space is secured between the through hole 2 g and the outer peripheral surface of the shaft 4 .

As shown in FIGS. 21 and 22, the bearing 3 has an outer ring 3a, an inner ring 3b, side faces 3c and side faces 3d. A side surface 3c of the bearing 3 is a side surface of the outer ring 3a in the axial direction Td of the shaft 4 indicated by an arrow in FIG. 21, and a side surface 3d of the bearing 3 is a side surface of the inner ring 3b in that direction. In addition, in the embodiment of the present invention, the (center) axial direction of the intermediate gear 2 or the shaft 4 is denoted as Td.

The outer ring 3a of the bearing 3 is press-fitted and fixed in the press-fit portion 2d, and the side surface 3c is fixed in contact with the bottom surface 2f. A shaft 4 is inserted inside the inner ring 3b. As shown in FIG. 21, the side surface 3d of the inner ring 3b contacts the contact surface 10c of the wall portion 80 of the main base 10. As shown in FIG. The contact surface 10c defines the position of the intermediate gear 2 in the axial direction Td. As described above, the intermediate gear 2 is biased by the plate spring 11 in the axial direction Td from the one end 4a of the shaft 4 toward the other end 4b of the shaft 4, so that the intermediate gear 2 is in contact with the bottom surface 2f. The side surface 3c of the outer ring 3a of the bearing 3 is also biased in the same direction. As a result, the inner ring 3b of the bearing 3 is also urged in the same direction, and the side surface 3d of the inner ring 3b of the bearing 3 contacts the contact surface 10c of the wall portion 80. As shown in FIG. As a result, the biasing force is transmitted to the contact surface 10c of the wall portion 80, and the intermediate gear 2 is stably supported in the axial direction Td of the shaft 4. Details of the biasing force will be described later.

The outer ring 3a of the bearing 3 is rotatably provided with respect to the inner ring 3b. Therefore, the intermediate gear 2 is rotatably supported by the shaft 4 at two points, the bearing portion 2c and the bearing 3 of the intermediate gear 2 shown in FIG. The shaft 4 is made of stainless steel, for example.

As shown in FIG. 21 , the wall portion 70 and the wall portion 80 are an example of a holding portion that holds the intermediate gear 2 rotatably via the shaft 4 . The wall portion 80 is integrally provided on the upper surface of the base portion 60 so as to form a pair with the wall portion 70 and extends from the upper surface of the base portion 60 in the positive Z-axis direction. The wall portion 80 is provided in a region on the second side 302 side of the center in the X-axis direction and on the third side 303 side of the center in the Y-axis direction in the entire upper surface of the base portion 60 in plan view. Further, the wall portion 80 is provided at a position closer to the second side 302 in the region and closer to the center in the Y-axis direction. The wall portion 70, the wall portion 80, and the shaft 4 function as a holding portion that holds the intermediate gear 2 rotatably. The shaft 4 is a cylindrical member and has one end 4a and the other end 4b. The other end 4b of the shaft 4 is press-fitted into a hole 10b formed in the wall portion 80 of the main base 10 and then fixed. On the other hand, the one end 4a of the shaft 4 only needs to be inserted into the hole 10a formed in the wall portion 70 and then positioned, and the one end 4a of the shaft 4 need not be press-fitted into the hole 10a. By inserting the one end 4a of the shaft 4 into the hole 10a rather than press-fitting it into the hole 10a, assembly of the shaft 4 becomes easier than when the one end 4a of the shaft 4 is press-fitted into the hole 10a.

As shown in FIG. 20 and the like, in the absolute encoder 100-2, the counter shaft gear 5 is provided on the side of the intermediate gear 2 opposite to the main shaft gear 1 side. For example, the sub-shaft gear 5 is arranged in a region near the corners of the main base 10 in the region surrounded by the four sides of the main base 10 . The corner portion is, for example, a portion where the second side 302 and the third side 303 shown in FIG. 20 intersect. In this manner, the subshaft gear 5 and the main shaft gear 1 are arranged so as to sandwich the intermediate gear 2 using a limited area on the main base 10 . This makes it possible to increase the distance from the sub-shaft gear 5 to the main shaft gear 1 compared to the case where the sub-shaft gear 5 and the main shaft gear 1 are arranged adjacent to each other without interposing the intermediate gear 2 therebetween. .

The magnetic sensor 40 can detect the rotation angle of the corresponding main shaft gear 1 by detecting a change in the magnetic flux generated by the permanent magnet 9 caused by the rotation of the permanent magnet 9 that rotates together with the main shaft gear 1 . On the other hand, the magnetic sensor 50 can detect the rotation angle of the corresponding subshaft gear 5 by detecting a change in the magnetic flux generated by the permanent magnet 8 due to the rotation of the permanent magnet 8 that rotates together with the subshaft gear 5 . .

Here, for example, when the main shaft gear 1 and the sub shaft gear 5 are arranged adjacent to each other, part of the magnetic flux generated by each of the permanent magnets 8 and 9 is transferred to each of the permanent magnets 8 and 9. So-called magnetic interference that affects magnetic sensors that are not compatible with

FIG. 34 shows the waveform (A) of the magnetic flux of the permanent magnet 9 provided on the main shaft gear 1 detected by the magnetic sensor 40 when the main shaft gear 1 is rotated, and the magnetic flux of the permanent magnet 8 provided on the sub shaft gear 5. The concept of the waveform (B) detected by the magnetic sensor 50 and the magnetic interference waveform (C) detected by the magnetic sensor 40 in a state in which a part of the magnetic flux of the permanent magnet 8 is superimposed on the magnetic flux of the permanent magnet 9 as leakage flux It is a figure showing. The vertical axis represents the magnetic flux, and the horizontal axis represents the rotation angle of the main shaft gear 1 . Thus, in the magnetic sensor 40, although it is desirable to detect the waveform of (A), when magnetic interference occurs, the waveform becomes as shown in (C), and an accurate waveform cannot be detected. Gone.

Similarly, FIG. 35 shows a waveform (A) of the magnetic flux of the permanent magnet 8 provided on the countershaft gear 5 detected by the magnetic sensor 50 when the main shaft gear 1 is rotated, and a waveform (A) of the permanent magnet provided on the main shaft gear 1 . 9 detected by the magnetic sensor 40, and a magnetic interference waveform (C) detected by the magnetic sensor 50 in a state in which part of the magnetic flux of the permanent magnet 9 is superimposed on the magnetic flux of the permanent magnet 8 as leakage flux. It is a figure showing the concept of. The vertical axis represents the magnetic flux, and the horizontal axis represents the rotation angle of the countershaft gear 5 . Thus, in the magnetic sensor 50, although it is desirable to detect the waveform of (A), when magnetic interference occurs, the waveform becomes as shown in (C), and an accurate waveform cannot be detected. Gone.

Therefore, according to the absolute encoder 100-2 according to the second embodiment, the main shaft gear 1 and the permanent magnet 9 and the sub shaft gear 5 and the permanent magnet 8 are arranged with the intermediate gear 2 therebetween at a distance from each other. Therefore, it is possible to reduce the occurrence of magnetic interference in which a part of the magnetic flux generated by each of the permanent magnets 8 and 9 affects a magnetic sensor that does not correspond to each of the permanent magnets 8 and 9. . For example, a magnetic sensor 50 provided for the original purpose of detecting a change in the magnetic flux generated by the permanent magnet 8 provided on the sub shaft gear 5 may detect the magnetic flux generated by the permanent magnet 9 provided on the main shaft gear 1 . can reduce interference as leakage magnetic flux. In addition, a part of the magnetic flux generated by the permanent magnet 8 provided on the counter shaft gear 5 is detected as leakage flux in the magnetic sensor 40 provided for the original purpose of detecting changes in the magnetic flux generated by the permanent magnet 9. Interference can be reduced.

As described above, according to the absolute encoder 100-2 according to the second embodiment, the rotation angle of the countershaft gear 5 detected by the magnetic sensor 50 can be detected while the dimension of the absolute encoder 100-2 in a plan view is relatively small. Alternatively, it is possible to prevent a decrease in detection accuracy of the amount of rotation. In addition, according to the absolute encoder 100-2, the size of the absolute encoder 100-2 when viewed from above is relatively small, while preventing deterioration in detection accuracy of the rotation angle or rotation amount of the main shaft gear 1 by the magnetic sensor 40. be able to.

As shown in FIG. 24, the sub-shaft gear 5 is a cylindrical member that is press-fitted into and fixed to the shaft portion 6b of the magnet holder 6. As shown in FIG. The countershaft gear 5 has a worm wheel portion 5a and a through hole 5b. The countershaft gear 5 is a member integrally molded of metal or resin, and is formed of polyacetal resin as an example here.

The worm wheel portion 5a is a gear that meshes with the worm gear portion 2b. The worm wheel portion 5a is an example of a second driven gear. The worm wheel portion 5 a is composed of a plurality of teeth provided on the outer peripheral portion of the cylindrical portion of the countershaft gear 5 . In FIG. 19, as the intermediate gear 2 rotates, the rotational force of the intermediate gear 2 is transmitted to the countershaft gear 5 via the worm gear portion 2b and the worm wheel portion 5a.

The through hole 5 b is a hole that penetrates along the central axis of the cylindrical countershaft gear 5 . The shaft portion 6b of the magnet holder 6 is press-fitted into the through hole 5b, and the sub-shaft gear 5 rotates integrally with the magnet holder 6. As shown in FIG.

As shown in FIGS. 24 and 32, the magnet holder 6 has a magnet holding portion 6a, a shaft portion 6b, and a head 6c. The magnet holder 6 is a member integrally molded of metal or resin, and is made of non-magnetic stainless steel as an example here.

Outer rings 7a of two bearings 7 are press-fitted into an inner peripheral surface 10dc of a bearing holder portion 10d formed on the main base 10. As shown in FIG. Each of the two bearings 7 has an outer ring 7a and an inner ring 7b.

The shaft portion 6b of the magnet holder 6 is a cylindrical member and is press-fitted into the through-hole 5b of the countershaft gear 5, and the lower portion of the shaft portion 6b is inserted into the inner rings 7b of the two bearings 7. As shown in FIG. Therefore, the magnet holder 6 is pivotally supported with respect to the main base 10 by the two bearings 7 and rotates integrally with the sub shaft gear 5 .

A head 6 c is provided at the upper end of the magnet holder 6 . The head 6c is a bottomed cylindrical member. A magnet holding portion 6a is formed in the head 6c. The magnet holding portion 6a is a recess that is recessed downward from the upper end surface of the head 6c. The outer peripheral surface of the permanent magnet 8 arranged in the magnet holding portion 6a is in contact with the inner peripheral surface of the head 6c. As a result, the permanent magnet 8 is fixed to the magnet holding portion 6a of the head 6c.

Since the shaft portion 6b of the magnet holder 6 is pivotally supported by two bearings 7 disposed in the bearing holder portion 10d formed on the main base 10, the magnet holder 6 can be prevented from tilting. Therefore, if the two bearings 7 are arranged as far apart as possible in the axial direction of the shaft portion 6b, the effect of preventing the magnet holder 6 from tilting can be expected.

As shown in FIG. 24, the upper portion 10db of the bearing holder portion 10d is the upper region of the bearing holder portion 10d in the Z-axis direction in the entire bearing holder portion 10d. One bearing 7 is provided inside the upper portion 10db of the bearing holder portion 10d. Further, the lower portion 10da of the bearing holder portion 10d is a lower region of the bearing holder portion 10d in the Z-axis direction in the entire bearing holder portion 10d. One bearing 7 is provided inside the lower portion 10da of the bearing holder portion 10d.

As shown in FIG. 24, a notch 202a is provided in a portion of the housing 202 of the motor 200. As shown in FIG. The notch portion 202a is a depression that is depressed toward the Z-axis negative direction side. Since the lower part 10da of the bearing holder part 10d is protruded from the main base 10, the casing 202 of the motor 200 is provided with a notch 202a to prevent mutual interference. A lower portion 10da of the bearing holder portion 10d is a lower region of the bearing holder portion 10d in the Z-axis direction in the entire bearing holder portion 10d. One bearing 7 is provided inside the lower portion 10da of the bearing holder portion 10d. By providing the notch 202a in the housing 202 of the motor 200 in this way, it is possible to set the two bearings 7 apart from each other in the Z-axis direction as compared to the case where the notch 202a is not provided. It is possible. The upper portion 10db of the bearing holder portion 10d is the upper region of the bearing holder portion 10d in the Z-axis direction in the entire bearing holder portion 10d.

If the bearing 7 is installed at a position closer to the magnet holding portion 6a and the permanent magnet 8 in the axial direction of the shaft portion 6b of the magnet holder 6, it is possible to reduce shaft shake during rotation of the magnet holder 6 and the permanent magnet 8. . On the other hand, since the outer diameter of the upper portion 10db of the bearing holder portion 10d is close to the intermediate gear 2, the upper portion 10db of the bearing holder portion 10d is formed with a slope to avoid interference with the addendum circle of the intermediate gear 2. In addition, it is possible to install the bearing 7 at a position closer to the magnet holding portion 6a and the permanent magnet 8.

The magnetic sensor 40 can detect the rotation angle of the corresponding main shaft gear 1 by detecting a change in the magnetic flux generated by the permanent magnet 9 caused by the rotation of the permanent magnet 9 that rotates together with the main shaft gear 1 . On the other hand, the magnetic sensor 50 can detect the rotation angle of the corresponding subshaft gear 5 by detecting a change in the magnetic flux generated by the permanent magnet 8 due to the rotation of the permanent magnet 8 that rotates together with the subshaft gear 5 . .

As shown in FIGS. 24 and 32, the permanent magnet 8 has a surface 8a. The permanent magnet 8 has a substantially cylindrical shape. The center axis GC1 of the gear 5 and the center axis BC of the bearing 7 are aligned. The surface 8a of the permanent magnet 8 faces the surface 50a of the magnetic sensor 50 at a certain distance. By aligning the respective central axes in this way, it becomes possible to detect the rotation angle or rotation amount with higher accuracy.

In this embodiment, as shown in FIG. 32, the two magnetic poles (N/S) of the permanent magnet 8 are arranged within a plane (XY plane) perpendicular to the central axis MC1 of the permanent magnet 8. formed side by side. That is, it is desirable that the center of rotation of the permanent magnet 8 coincides with the center of the magnetic pole boundary on the central axis MC1. This further improves the detection accuracy of the rotation angle or rotation amount.

As shown in FIGS. 23 and 33, the permanent magnet 9 is a substantially cylindrical permanent magnet press-fitted inside the magnet holding portion 1h of the main shaft gear 1, and has an upper surface 9a and a lower surface 9b. The upper surface 9a faces the surface 40a of the magnetic sensor 40 at a certain distance. The lower surface 9b is in contact with the bottom surface 1g of the magnet holding portion 1h of the main shaft gear 1, and defines the position of the main shaft gear 1 in the central axis GC2 direction (the position in the Z-axis direction). The central axis MC2 of the permanent magnet 9 (the axis representing the center of the permanent magnet 9 or the axis passing through the center of the magnetic pole boundary) coincides with the central axis GC2 of the main shaft gear 1 and the central axis RC of the motor shaft 201. . By aligning the respective central axes in this way, it becomes possible to detect the rotation angle or rotation amount with higher accuracy.

In this embodiment, as shown in FIG. 33, the two magnetic poles (N/S) of the permanent magnet 9 are arranged within a plane (XY plane) perpendicular to the central axis MC2 of the permanent magnet 9. It is desirable that they are formed side by side. This further improves the detection accuracy of the rotation angle or rotation amount.

Each of the permanent magnets 8 and 9 is made of a magnetic material such as ferrite, Nd (neodymium)--Fe (iron)--B (boron). Each of the permanent magnets 8 and 9 may be, for example, a rubber magnet containing a resin binder, a bond magnet, or the like.

FIG. 28 shows positioning holes 20a, positioning holes 20b, holes 20c, holes 20d, and holes 20e, which are a plurality of through holes formed in the substrate 20. FIG. The shape of the wall surface forming the positioning hole 20a is, for example, a circle. The shape of the wall surface forming the positioning hole 20b is, for example, an ellipse. Each of the holes 20c, 20d, and 20e is a through hole for fixing the board 20 to the main base 10 with the board mounting screws 13 shown in FIG. The shape of the wall surface forming each of the holes 20c, 20d and 20e is, for example, a circle. The diameter of the wall surface forming each of the holes 20 c , 20 d and 20 e is larger than the diameter of the male threaded portion of the board mounting screw 13 and smaller than the diameter of the head of the board mounting screw 13 .

As shown in FIGS. 18 to 21, 25 to 27, etc., the main base 10 includes a hole 10a, a hole 10b, a contact surface 10c, a bearing holder portion 10d, a leaf spring mounting surface 10e, a base portion 60, a wall portion 70, and a , a wall portion 80, an opening 10-1, and a screw hole 10f. The main base 10 has a board positioning pin 10g, a board positioning pin 10j, a tip 10h, a tip 10k, a column 10m, a column 10q, a column 10s, a screw hole 10u, a screw hole 10v, and a screw hole 10w. The board positioning pin 10g, the board positioning pin 10j, the column 10m, the column 10q, and the column 10s are examples of columnar members. A step portion 10i is formed between the tip portion 10h of the board positioning pin 10g extending in the Z-axis direction from the main base 10 and the base portion 10g1 of the board positioning pin 10g. When the tip portion 10h of the substrate positioning pin 10g is inserted into the positioning hole 20a formed in the substrate 20, a gap is formed between the lower surface 20-1 of the substrate 20 and the stepped portion 10i. Similarly, a step portion 10l is formed between a tip portion 10k of a substrate positioning pin 10j extending in the Z-axis direction from the main base 10 and a base portion 10j1 of the substrate positioning pin 10j. When the tip portion 10k of the substrate positioning pin 10j is inserted into the positioning hole 20b formed in the substrate 20, a gap is formed between the lower surface 20-1 of the substrate 20 and the stepped portion 10l. Thus, when the two substrate positioning pins 10g and 10j are used, the position of the substrate 20 in the direction orthogonal to the Z-axis direction is defined. However, since a gap is formed between each of the stepped portions 10i and 10l and the substrate 20, the position of the substrate 20 in the Z-axis direction is defined by the two substrate positioning pins 10g and 10j. no.

The base portion 60 of the main base 10 is, for example, an integrally molded aluminum die-cast member, and is a substantially square plate-like member in a plan view. The base portion 60 is an example of a plate portion. Base 60 is attached to the top surface of motor 200 .

The opening 10-1 shown in FIG. 18 penetrates the base 60 in the thickness direction (Z-axis direction). The main shaft gear 1 is inserted through the opening 10-1. The opening 10-1 is an example of a first through hole.

As shown in FIGS. 19, 20, 25, 26, etc., the wall portion 70 has a wall portion 71 and a wall portion 72. As shown in FIGS. The wall portion 70 has the function of supporting the shaft 4 and fixing the leaf spring 11 . The wall portion 71 is integrally provided on the upper surface of the base portion 60 and extends from the base portion 60 in the positive Z-axis direction. The wall portion 70 is provided in a region on the first side 301 side of the center in the X-axis direction and on the fourth side 304 side of the center in the Y-axis direction in the entire upper surface of the base portion 60 in plan view. The wall portion 71 has a mounting surface 10ad located on the positive side of the X-axis and a screw hole 10ae penetrating in the X-axis direction. As shown in FIGS. 16, 29, and 30, the mounting screws 16 are inserted through the holes 15d of the case 15 and screwed into the screw holes 10ae so that the mounting surface 10ad of the wall portion 71 is mounted on the case 15. The inner surface abuts and is fixed.

As shown in FIG. 20, the wall portion 72 is located on the side of the first side 301 from the center in the X-axis direction and on the third side 303 from the center in the Y-axis direction in the entire upper surface of the base portion 60 in plan view. provided in the side area. The wall portion 72 is connected to the wall portion 71 and extends from the wall portion 71 toward the vicinity of the center of the third side 303 . An end portion of the wall portion 72 on the side of the third side 303 is connected to the pillar 10s. The pillar 10s connected to the wall portion 72 is provided at a position near the center of the main base 10 in the X-axis direction and at a position near the third side 303 of the main base 10 . Thus, the wall portion 72 extends from the wall portion 71 toward the pillar 10s. That is, the wall portion 72 extends obliquely with respect to each of the X-axis and the Y-axis in plan view.

As shown in FIG. 26, the screw 12 is inserted through the hole 11c formed in the mounting portion 11b of the leaf spring 11 and screwed into the screw hole 10f formed in the wall portion 72 of the main base 10. As shown in FIG. As a result, the mounting portion 11 b of the leaf spring 11 comes into contact with the leaf spring mounting surface 10 e formed on the wall portion 72 , and the leaf spring 11 is fixed to the wall portion 72 . The wall portion 72 functions as a fixing portion to which the leaf spring 11 is fixed. At this time, as shown in FIGS. 20 and 21, the sliding portion 11a of the leaf spring 11 comes into contact with the sliding portion 2e of the intermediate gear 2 into which the shaft 4 is inserted.

The mounting angle θ shown in FIG. 21 will be described. Since the worm gear portion 1d of the main shaft gear 1 is meshed with the worm wheel portion 2a, as the worm gear portion 1d of the main shaft gear 1 rotates, the intermediate gear 2 moves from the other end 4b of the shaft 4 to the one end of the shaft 4. A first thrust force is generated in the direction toward 4 a or in the direction from one end 4 a of shaft 4 toward the other end 4 b of shaft 4 . Furthermore, the meshing of the worm gear portion 2b with the worm wheel portion 5a of the auxiliary shaft gear 5 also allows the intermediate gear 2 to move in the direction from the other end 4b of the shaft 4 toward the one end 4a of the shaft 4 or in the direction toward one end of the shaft 4. A second thrust force is generated in the direction from 4 a toward the other end 4 b of shaft 4 . Thus, in order to accurately transmit the amount of rotation of the worm gear portion 1d of the main shaft gear 1 to the worm wheel portion 5a of the sub shaft gear 5 even when the first thrust force and the second thrust force are generated, the shaft 4 It is necessary to suppress the movement of the intermediate gear 2 in the axial direction Td. The leaf spring 11 applies a biasing force to the intermediate gear 2 in a direction from one end 4 a of the shaft 4 toward the other end 4 b of the shaft 4 . The biasing force generated by the leaf spring 11 is set to a higher value than the sum of the first thrust force and the second thrust force in the direction from the other end 4b of the shaft 4 toward the one end 4a of the shaft 4. .

In FIG. 21, the mounting angle .theta. It is equal to the angle formed by the side surface 73 of the intermediate gear 2 side of the surface of the wall portion 72 on which the hole 10a is formed. In this embodiment, the side surface 73 and the shaft 4 are perpendicular to each other, but this need not be the case. When the intermediate gear 2 is mounted on the shaft 4, the sliding portion 11a of the leaf spring 11 comes into contact with the sliding portion 2e of the intermediate gear 2, and the leaf spring 11 is deflected by a predetermined amount. 2 to give an appropriate biasing force to the shaft 4 in the axial direction Td. Therefore, the leaf spring 11 urges the intermediate gear 2 in the direction from the one end 4a side of the shaft 4 to the other end 4b side of the shaft 4, so that the direction from the other end 4b of the shaft 4 to the one end 4a of the shaft 4 Movement of the intermediate gear 2 due to the total force of the first thrust force and the second thrust force is suppressed. As a result, it is possible to prevent deterioration of the rotational accuracy of the countershaft gear 5 . It should be noted that the greater the biasing force, the greater the sliding resistance when the intermediate gear 2 shown in FIG. 21 rotates. Therefore, the mounting angle θ is set to an appropriate value so as to generate a sufficient biasing force that can suppress the movement of the intermediate gear 2 due to the thrust force while minimizing the sliding resistance when the intermediate gear 2 rotates. should be set to In order to set the mounting angle .theta. There is a need.

In the absolute encoder 100-2 according to the second embodiment, since the main base 10 is made of die-cast aluminum, compared to the case where the base portion 60 and the wall portion 70, which are individually manufactured by, for example, sheet metal, are combined with each other. Therefore, the mounting angle error of the wall portion 70 to the base portion 60 can be reduced, and the surface accuracy of the plate spring mounting surface 10e is improved. As a result, the error in the attachment angle θ of the leaf spring 11 to the wall portion 72 is reduced, and the biasing force can be easily managed.

As shown in FIG. 25, the main base 10 is fixed by inserting three screws 14 through three holes formed in the main base 10 and screwing them into screw holes formed in the motor 200. be done. A threaded hole 10v, a threaded hole 10u and a threaded hole 10w are formed on the leading end sides of the columns 10q, 10m and 10s extending in the positive Z-axis direction from the main base 10, respectively. Board mounting screws 13 inserted through holes 20c, 20e and 20d formed in the board 20 shown in FIG. 17 are screwed into the respective screw holes 10v, 10u and 10w. As a result, the top surfaces 10r, 10p and 10t of the columns 10q, 10m and 10s are in contact with the bottom surface 20-1 of the substrate 20 shown in FIG. The bottom surface 20-1 of the substrate 20 is the surface facing the main base 10 among the two substrate surfaces of the substrate 20 in the Z-axis direction. As a result, the position of the substrate 20 in the Z-axis direction is defined.

As shown in FIGS. 16, 29 to 31, etc., the case 15 has an upper surface portion 15-1, a first side surface portion 15A, a second side surface portion 15B, a third side surface portion 15C, and a fourth side surface portion 15D. It is a box-shaped member with one side open. The case 15 is made of resin, for example, and is an integrally molded member. The top surface 15-1 corresponds to the bottom of the box-shaped member. The upper surface portion 15-1 is a surface facing the upper surface 20-2 of the substrate 20 shown in FIG. The upper surface 20-2 of the substrate 20 is the substrate surface opposite to the lower surface 20-1 of the substrate 20. As shown in FIG. The first side surface portion 15A is a plate-like member extending in the negative Z-axis direction from the side portion of the upper surface portion 15-1 on the positive X-axis direction side. The second side surface portion 15B is a plate-like member extending in the negative Z-axis direction from the side portion of the upper surface portion 15-1 on the negative X-axis direction side. The third side surface portion 15C is a plate-like member extending in the negative Z-axis direction from the side portion of the upper surface portion 15-1 on the negative Y-axis direction side. The fourth side surface portion 15D is a plate-like member extending in the negative Z-axis direction from the side portion of the upper surface portion 15-1 on the positive Y-axis direction side. The shape of the case 15 in plan view is a rectangular shape corresponding to the shape of the motor 200 in plan view. A space inside the case 15 accommodates a plurality of components of the absolute encoder 100-2.

As shown in FIG. 30, the case 15 has claws 15a, claws 15b, claws 15c, a hole 15d, a recess 15e, a recess 15f, a recess 15g, a connector case portion 15h, and an opening 15i. The claw 15a is provided near the end of the fourth side surface portion 15D in the negative direction of the Z axis. The claw 15a extends in the Y-axis negative direction from the fourth side surface portion 15D so as to face the third side surface portion 15C. The claw 15a is engaged with a recess 10aa provided in the main base 10 shown in FIG. The claw 15b is provided near the end of the third side surface portion 15C in the negative direction of the Z axis. The claw 15b extends in the positive direction of the Y-axis from the third side surface portion 15C so as to face the fourth side surface portion 15D. The claw 15b is engaged with a recess 10ab provided in the main base 10 shown in FIG. The claw 15c is provided near the end of the second side surface portion 15B in the negative direction of the Z axis. The claw 15c extends in the X-axis negative direction from the second side surface portion 15B so as to face the first side surface portion 15A. The claw 15c is engaged with a recess 10ac provided in the main base 10 shown in FIG.

The recess 15e, recess 15f, and recess 15g shown in FIG. 30 are partially formed on the upper surface 5-1 of the case 15 in order to avoid interference with the heads of the three board mounting screws 13 shown in FIG. This recess is formed so as to be recessed in the positive direction of the Z-axis.

The connector case portion 15h is a recess formed by partially recessing the upper surface 5-1 of the case 15 in the positive direction of the Z-axis in order to cover the connector 24 shown in FIG. The shape of the bottom surface of the connector case portion 15h in plan view is a rectangle. The connector case portion 15h is provided in a region of the upper surface 5-1 closer to the first side surface portion 15A than the center in the X-axis direction and near the center in the Y-axis direction. Further, the connector case portion 15h is provided in a portion closer to the first side surface portion 15A in the region.

The opening 15i is formed between the bottom surface of the connector case portion 15h and the first side surface portion 15A. Connector 24 shown in FIG. 17 is arranged to face the bottom surface of connector case portion 15h. The connector 24 is, for example, a female connector, and a male connector provided at one end of the external wiring is inserted into the connector 24 . The male connector is inserted through the opening 15i shown in FIG. 30 into the connector 24 arranged in the connector case 15h. As a result, the conductive terminals of the male connector provided at one end of the external wiring are electrically connected to the conductive terminals provided on the connector 24 . As a result, the connector 24 is electrically connected to the external device connected to the other end of the external wiring, enabling signal transmission between the absolute encoder 100-2 and the external device.

Further, by providing the connector case portion 15h at a position closer to the first side surface portion 15A, as shown in FIG. equal to position. By configuring the absolute encoder 100-2 in this way, the position where the external wiring electrically connected to the conductive pins provided on the connector 24 is pulled out is electrically connected to the conductive pins provided on the connector 400. It is possible to approach the position where the external wiring to be connected is drawn out. Therefore, these external wires can be bundled together near the absolute encoder 100-2 and the motor 200, and the bundled wire group can be easily routed to the external device.

As shown in FIG. 28, the lower surface 20-1 of the substrate 20 is provided with the magnetic sensor 40, the magnetic sensor 50, the microcomputer 21, the bidirectional driver 22, and the line driver 23. FIG. A lower surface 20-1 of the substrate 20 is a mounting surface for the magnetic sensors 40 and 50. FIG. As described above, the bottom surface 20-1 of the substrate 20 is in contact with the top surface 10r of the column 10q, the top surface 10p of the column 10m, and the top surface 10t of the column 10s. As shown in FIG. 19, the pillars 10q, 10m, and 10s are provided on the main base 10 so that the difference in distance between them when the main base 10 is viewed from above is small. For example, the column 10q is provided near the second side 302 near the center of the main base 10 in the Y-axis direction. The pillar 10q is integrated with the wall portion 80. As shown in FIG. The pillar 10m is provided near the corner where the first side 301 and the fourth side 304 intersect. The column 10s is provided near the third side 303 in the vicinity of the center of the main base 10 in the X-axis direction. The post 10s is integrated with the wall portion 70 and the board positioning pin 10g. By providing the pillars 10q, 10m, and 10s in this manner, the positions of the magnetic sensors 40 and 50 provided on the substrate 20 in the Z-axis direction can be accurately defined. If the pillars 10q, 10m, and 10s are formed on the main base 10 as far apart as possible in the XY plane direction, the position of the substrate 20 can be held more stably.

In absolute encoder 100-2 according to the second embodiment, main base 10 is formed by die casting. Therefore, for example, the base 60 of the main base 10 is manufactured by sheet metal, and the columns 10q, 10m, 10s, the board positioning pins 10g, the board positioning pins 10j, the walls 70, 80, etc. are separately manufactured and assembled. The positional accuracy between each part is improved compared to the case. In addition, by reducing the number of parts in manufacturing, the structure of the absolute encoder 100-2 can be simplified, the assembly can be facilitated, the manufacturing time can be shortened, and the reliability of the absolute encoder 100-2 can be improved. be able to.

The magnetic sensor 40 is an example of a spindle angle sensor. The magnetic sensor 40 is arranged right above the permanent magnet 9 with a predetermined space therebetween. The magnetic sensor 40 detects and identifies the rotation angle of the corresponding main shaft gear 1 by detecting a change in the magnetic flux generated from the permanent magnet 9 caused by the rotation of the permanent magnet 9 that rotates together with the main shaft gear 1, and detects the identified rotation angle. is output as a digital signal.

Magnetic sensor 50 is an example of an angle sensor. Also, the countershaft gear 5 is a rotating body that rotates according to the rotation of the worm wheel portion 5a that is the second driven gear. The magnetic sensor 50 is arranged right above the permanent magnet 8 with a predetermined space therebetween. The magnetic sensor 50 detects and specifies the rotation angle of the corresponding subshaft gear 5 by detecting a change in the magnetic flux generated from the permanent magnet 8 due to the rotation of the permanent magnet 8 that rotates together with the subshaft gear 5. Angle information indicating the rotation angle is output as a digital signal.

Each of the magnetic sensors 40 and 50 includes, for example, a sensing element that senses changes in magnetic flux, and an arithmetic circuit that outputs a digital signal representing the rotation angle based on the output of the sensing element. The sensing element may be a combination of a plurality of magnetic field sensing elements such as Hall elements and GMR (Giant Magneto Resistive) elements. The number of magnetic field sensing elements is for example four.

When the number of threads of the worm gear portion 1d of the main shaft gear 1 is four and the number of teeth of the worm wheel portion 2a of the intermediate gear 2 is twenty, the reduction ratio is five. That is, when the main shaft gear 1 rotates five times, the intermediate gear 2 rotates once. Further, when the number of threads of the worm gear portion 2b of the intermediate gear 2 is 1 and the number of teeth of the worm wheel portion 5a of the countershaft gear 5 is 18, the reduction ratio is 18. That is, when the intermediate gear 2 rotates 18 times, the countershaft gear 5 rotates once. Therefore, when the main shaft gear 1 rotates 90 times, the intermediate gear 2 rotates 90/5=18 times, and the sub shaft gear 5 rotates 18/18=1 time.

The main shaft gear 1 and the sub shaft gear 5 are provided with permanent magnets 9 and 8 that rotate integrally with each other. Therefore, the rotation amount of the motor shaft 201 can be specified by detecting the rotation angles of the main shaft gear 1 and the sub shaft gear 5 with the corresponding magnetic sensors 40 and 50 . When the main shaft gear 1 rotates once, the counter shaft gear 5 rotates 1/90, that is, 4°. Therefore, when the rotation angle of the sub-shaft gear 5 is less than 4 degrees, the rotation amount of the main shaft gear 1 is less than one rotation. is more than 1 rotation and less than 2 rotations. In this manner, the absolute encoder 100-2 can specify the rotation speed of the main shaft gear 1 according to the rotation angle of the sub shaft gear 5. FIG. In particular, the absolute encoder 100-2 utilizes the speed reduction ratio between the worm gear portion 1d and the worm wheel portion 2a and the speed reduction ratio between the worm gear portion 2b and the worm wheel portion 5a, so that the number of rotations of the main shaft gear 1 can be increased by a plurality of rotations. However, the rotation speed of the main shaft gear 1 can be specified.

The microcomputer 21 , bidirectional driver 22 , line driver 23 and connector 24 are mounted on the board 20 . The microcomputer 21 , bidirectional driver 22 , line driver 23 and connector 24 are electrically connected by pattern wiring on the substrate 20 .

The microcomputer 21 is composed of a CPU (Central Processing Unit), acquires digital signals representing rotation angles output from the magnetic sensors 40 and 50, and calculates the amount of rotation of the main shaft gear 1. do.

Bidirectional driver 22 performs bidirectional communication with an external device connected to connector 24 . The bidirectional driver 22 converts data such as operation signals into differential signals for communication with an external device. The line driver 23 converts data representing the amount of rotation into a differential signal and outputs the differential signal to an external device connected to the connector 24 in real time. A connector of an external device is connected to the connector 24 .

FIG. 36 is a diagram showing the functional configuration of microcomputer 21 included in absolute encoder 100-2 according to the second embodiment of the present invention. Each block of the microcomputer 21 shown in FIG. 36 represents a function realized by the CPU as the microcomputer 21 executing a program.

The microcomputer 21 includes a rotation angle acquisition section 21p, a rotation angle acquisition section 21q, a table processing section 21b, a rotation amount identification section 21c, and an output section 21e. The rotation angle acquisition unit 21q acquires the rotation angle Aq of the main shaft gear 1 based on the signal output from the magnetic sensor 40. FIG. The rotation angle Aq is angle information indicating the rotation angle of the main shaft gear 1 . The rotation angle acquisition unit 21p acquires the rotation angle Ap of the sub shaft gear 5 based on the signal output from the magnetic sensor 50. FIG. The rotation angle Ap is angle information indicating the rotation angle of the subshaft gear 5 . The table processing unit 21b refers to a correspondence table that stores the rotation angle Ap and the rotation speed of the main shaft gear 1 corresponding to the rotation angle Ap, and calculates the rotation speed of the main shaft gear 1 corresponding to the acquired rotation angle Ap. Identify. The rotation amount specifying unit 21c specifies the rotation amount of the main shaft gear 1 over a plurality of rotations according to the rotational speed of the main shaft gear 1 specified by the table processing unit 21b and the acquired rotation angle Aq. The output unit 21e converts the identified amount of rotation of the main shaft gear 1 over a plurality of rotations into information indicating the amount of rotation and outputs the information.

As described above, in the absolute encoder 100-2 according to Embodiment 2, as shown in FIG. Therefore, it is possible to reduce the occurrence of magnetic interference that affects magnetic sensors that do not correspond to the permanent magnets 8 and 9 respectively. In this way, the absolute encoder 100-2 employs a structure that can reduce the occurrence of magnetic interference, so that the size of the absolute encoder 100-2 can be made relatively small when viewed from above. Therefore, it is possible to prevent deterioration in the magnetic flux detection accuracy of each of the magnetic sensors 40 and 50 while miniaturizing the absolute encoder 100-2.

Further, in the absolute encoder 100-2 according to the second embodiment, the intermediate gear 2 arranged parallel to the upper surface of the main base 10 extends obliquely with respect to the four sides of the main base 10. A main shaft gear 1 and a counter shaft gear 5 are provided on opposite sides of the intermediate gear 2 from each other. Therefore, the main shaft gear 1, the intermediate gear 2, and the sub shaft gear 5 can be arranged in a narrow region of the entire upper surface of the main base 10, and the dimension of the absolute encoder 100-2 in the horizontal direction can be reduced. .

Further, in the absolute encoder 100-2 according to the second embodiment, the outer diameter of the worm wheel portion 2a and the outer diameter of the worm gear portion 2b are set to small values within the possible range. As a result, the dimension in the Z-axis direction (height direction) of the absolute encoder 100-2 can be reduced.

As described above, according to the absolute encoder 100-2 according to the second embodiment, the dimension in the Z-axis direction and the dimension in the direction perpendicular to the Z-axis direction can be detected while preventing deterioration in detection accuracy of the amount of rotation of the main shaft gear 1. and can be made smaller.

Further, in the absolute encoder 100-2 according to the second embodiment, the intermediate gear 2 is axially supported, that is, rotatably supported by the shaft 4 fixed or inserted in each of the wall portion 80 and the wall portion 72. However, the method of supporting the intermediate gear 2 is not limited to this as long as the intermediate gear 2 can be pivotally supported.

For example, the absolute encoder 100-2 is configured such that one end 4a of the shaft 4 is inserted into a hole 10a formed in the wall portion 72, and the other end 4b of the shaft 4 is press-fitted into a hole 10b formed in the wall portion 80. configured to Further, the absolute encoder 100-2 is configured such that the outer ring 3a of the bearing 3 is press-fitted into the press-fitting portion 2d formed in the intermediate gear 2, and the shaft 4 is press-fitted into the inner ring 3b of the bearing 3. good too. This restricts the movement of the intermediate gear 2 fixed to the shaft 4 in the axial direction Td. Even when the absolute encoder 100-2 is configured in this manner, the intermediate gear 2 is supported by the shaft 4. As shown in FIG. Furthermore, the axial movement of the shaft 4 in the axial direction Td is restricted by the walls 72 and 80, and the axial movement of the intermediate gear 2 is also restricted by the inner ring 3b of the bearing 3 fixed to the shaft 4. . Therefore, the leaf spring 11 becomes unnecessary.

In addition, for example, the absolute encoder 100-2 is provided on at least one of the wall portion 72 and the wall portion 80 with the intermediate gear 2 fixed to the shaft 4 without using the bearing 3 shown in FIG. The shaft 4 may be supported by bearings (not shown).

When the outer ring of the bearing (not shown) is fixed to the wall portion 72 or the wall portion 80 and the one end 4a or the other end 4b of the shaft 4 is inserted into the inner ring, the intermediate gear 2 is fixed to the shaft 4 and the shaft 4 is not shown. , the shaft 4 and the intermediate gear 2 can rotate together. In this case, the shaft 4 is not fixed to the inner ring of the bearing, but merely inserted into the inner ring, so that the shaft 4 can move along with the intermediate gear 2 in the axial direction Td. Therefore, the leaf spring 11 is required to urge the intermediate gear 2 in the axial direction Td and to regulate the position.

Alternatively, the outer ring of the bearing (not shown) may be fixed to the wall portion 72 or the wall portion 80, and the one end 4a or the other end 4b of the shaft 4 may be press-fitted into the inner ring (not shown). At this time, the movement of the intermediate gear 2 fixed to the shaft 4 in the axial direction Td is restricted. Therefore, not only is the intermediate gear 2 fixed to the shaft 4 rotatably supported by bearings (not shown), but also the movement of the shaft 4 in the axial direction Td is restricted. movement is also restricted. Therefore, the leaf spring 11 becomes unnecessary.

As shown in FIG. 23, the magnetic sensor 40 originally detects and specifies the rotation angle of the main shaft gear 1 by detecting changes in the magnetic flux from the permanent magnet 9 that rotates together with the main shaft gear 1 . Further, as shown in FIG. 24, the magnetic sensor 50 detects changes in the magnetic flux of the permanent magnet 8 that rotates together with the subshaft gear 5 to detect and specify the rotation angle of the subshaft gear 5 . Absolute encoder 100-2 of the second embodiment can reduce the influence of magnetic flux from permanent magnet 8 on magnetic sensor 40 by adopting a structure capable of reducing the occurrence of magnetic interference, as described above. Also, the influence of the magnetic flux from the permanent magnet 9 on the magnetic sensor 50 can be reduced. In other words, it is possible to prevent deterioration in rotation detection accuracy due to mutual magnetic interference between the main shaft gear 1 and the sub shaft gear 5 .

FIG. 16 shows a state in which the absolute encoder 100-2 is attached to the motor 200. The motor 200 has a built-in permanent magnet and a driving coil. Therefore, the motor 200 generates magnetic flux even when the motor shaft 201 is not rotating. Further, when a drive signal is applied to the motor 200 from the outside to rotate the motor shaft 201, the generated magnetic flux further increases. The magnetic flux generated by the motor 200 may adversely affect the magnetic sensors 40 and 50 provided inside the absolute encoder 100-2, resulting in deterioration of detection accuracy. If the main base 10 is made of a ferromagnetic material such as iron, the influence of the magnetic flux from the motor 200 can be reduced.

In addition to the motor 200, even if other electronic equipment or the like is arranged near the outside of the absolute encoder 100-2, the magnetic flux generated from the equipment or the like may cause a magnetic flux generated inside the absolute encoder 100-2. The sensor 40 and the magnetic sensor 50 may be adversely affected.

Absolute encoder 100-2 according to the modification of the second embodiment is configured in view of such problems.

FIG. 37 is a plan view showing a modification of absolute encoder 100-2 according to the second embodiment of the present invention. 38 is a perspective view showing a state in which the intermediate gear 2 is removed from among the multiple parts shown in FIG. 37. FIG. FIG. 39 is a cross-sectional view of the magnetic flux shielding portion 61 shown in FIG. FIG. 40 is a cross-sectional view of the magnetic flux shielding portion 62 shown in FIG. 37 and 38 show only essential components of absolute encoder 100-2 according to the modification of the second embodiment. FIG. 38 shows the magnetic flux shielding portion 61 and the magnetic flux shielding portion 62 shown in FIG. 37, respectively.

An absolute encoder 100-2 according to a modification of the second embodiment is provided with a magnetic flux shielding portion 61 and a magnetic flux shielding portion 62 at a base portion 60 of a main base 10. FIG. The magnetic flux shielding portion 61 is an arc-shaped plate member provided at a position facing the worm gear portion 1d. The magnetic flux shielding portion 61 has a first plate surface 61a facing the worm gear portion 1d and a second plate surface 61b opposite to the first plate surface 61a side of the magnetic flux shielding portion 61 . Each of the first plate surface 61a and the second plate surface 61b curves projectingly in the direction from the first plate surface 61a toward the second plate surface 61b. The first plate surface 61a of the magnetic flux shielding portion 61 is provided at a position spaced apart from the worm gear portion 1d by a certain distance so as not to interfere with the worm gear portion 1d.

The magnetic flux shielding portion 61 has a first end face 61c facing the worm wheel portion 2a, a second end face 61d facing the wall portion 80, and a third end face 61e facing the lower surface 20-1 of the substrate 20 shown in FIG. . The first end face 61c of the magnetic flux shielding portion 61 is provided at a position spaced apart from the intermediate gear 2 by a certain distance so as not to interfere with the intermediate gear 2. As shown in FIG. The second end face 61d of the magnetic flux shielding portion 61 is provided at a position spaced apart from the intermediate gear 2 by a certain distance so as not to interfere with the intermediate gear 2. As shown in FIG. A third end surface 61e of the magnetic flux shielding portion 61 is a front end surface of the magnetic flux shielding portion 61 in the positive direction of the Z axis.

The magnetic flux shielding portion 61 extends from the base portion 60 of the main base 10 in the positive Z-axis direction. For example, the magnetic flux shielding portion 61 is provided at the base portion 60 of the main base 10 so that an imaginary line extending in the Z-axis positive direction from the wall surface 10-1a forming the opening 10-1 passes over the first plate surface 61a. . The magnetic flux shielding part 61 is, for example, a member made of a ferromagnetic material such as iron. Note that the magnetic flux shielding portion 61 is not limited to one manufactured separately from the base portion 60 of the main base 10, and the absolute encoder 100-2 according to the modification of the second embodiment can be manufactured by pressing, forging, casting, lost wax, or the like. The base 60 of the main base 10 and the magnetic flux shielding part 61 integrally molded from a ferromagnetic material by the manufacturing method of 1. above may be used.

The height of the magnetic flux shielding portion 61 in the Z-axis direction is equal to the width in the Z-axis direction from the third end face 61 e of the magnetic flux shielding portion 61 to the base portion 60 of the main base 10 . As shown in FIG. 39, the position of the third end surface 61e of the magnetic flux shielding portion 61 may be provided above the position of the upper surface 9a of the permanent magnet 9 shown in FIG. 23 in the positive Z-axis direction. For example, the third end surface 61e of the magnetic flux shielding portion 61 may be provided so as to contact the lower surface 20-1 of the substrate 20. FIG. By setting the position of the third end surface 61 e of the magnetic flux shielding portion 61 in this way, it is possible to reduce the flow of unnecessary magnetic flux from the outside into the magnetic sensor 50 .

The magnetic flux shielding portion 62 is provided at a position facing the worm wheel portion 5a provided on the opposite side of the worm gear portion 1d of the worm wheel portion 2a. be. The magnetic flux shielding portion 62 includes a first plate surface 62a facing the head 6c of the magnet holder 6, and a second plate surface 62b opposite to the first plate surface 62a side of the magnetic flux shielding portion 62. Each of the first plate surface 62a and the second plate surface 62b is curved in a projecting shape in the direction from the first plate surface 62a toward the second plate surface 62b. The first plate surface 62a of the magnetic flux shielding portion 62 is arranged so as not to interfere with both the head 6c of the magnet holder 6 and the worm wheel portion 5a shown in FIG. 5a at a fixed distance.

The magnetic flux shielding portion 62 has a first end face 62c facing the wall portion 80, a second end face 62d facing the worm wheel portion 2a, and a third end face 62e facing the lower surface 20-1 of the substrate 20 shown in FIG. . The second end face 62d of the magnetic flux shielding portion 62 is spaced apart from the intermediate gear 2 by a certain distance so as not to interfere with the intermediate gear 2 when the intermediate gear 2 and the shaft 4 are attached to the wall portion 70 and the wall portion 80. placed in position. In the absolute encoder 100-2 according to the modification of the second embodiment, the first end surface 62c of the magnetic flux shielding portion 62 is provided at a position spaced apart from the wall portion 80 by a certain distance. , the first end surface 62 c may be configured to contact the wall portion 80 .

The magnetic flux shielding portion 62 extends from the base portion 60 of the main base 10 in the positive Z-axis direction. For example, an imaginary line extending in the Z-axis positive direction of the wall surface 10-3a forming the outer shape 10-3 of the upper portion 10db of the bearing holder portion 10d shown in FIGS. A magnetic flux shielding portion 62 is provided on the base portion 60 of the main base 10 so as to pass over the plate surface 62a. The magnetic flux shielding portion 62 is made of the same magnetic material as the magnetic flux shielding portion 61 . Note that the magnetic flux shielding portion 62 is not limited to one manufactured separately from the base portion 60 of the main base 10, and the absolute encoder 100-2 according to the modification of the second embodiment can be manufactured by pressing, forging, casting, lost wax, or the like. The base 60 of the main base 10 and the magnetic flux shielding part 62 integrally molded using a ferromagnetic material by the manufacturing method of .

The height of the magnetic flux shielding portion 62 in the Z-axis direction is equal to the width in the Z-axis direction from the third end surface 62e of the magnetic flux shielding portion 62 to the base portion 60 of the main base 10 . As shown in FIG. 40, the position of the third end surface 62e of the magnetic flux shielding portion 62 may be provided above the position of the surface 8a of the permanent magnet 8 shown in FIG. 24 in the Z-axis positive direction. For example, the third end surface 62e of the magnetic flux shielding portion 62 may be provided so as to contact the lower surface 20-1 of the substrate 20. FIG. By setting the position of the third end surface 62 e of the magnetic flux shielding portion 62 in this manner, it is possible to reduce the flow of unnecessary magnetic flux from the outside into the magnetic sensor 40 .

Although the absolute encoder 100-2 according to the modification of the second embodiment includes the magnetic flux shielding portion 61 and the magnetic flux shielding portion 62, only one of the magnetic flux shielding portion 61 and the magnetic flux shielding portion 62 is provided. It may be configured as Even with such a configuration, the magnetic sensor 40 is less likely to be affected by unnecessary magnetic flux from the outside than when both the magnetic flux shielding portion 61 and the magnetic flux shielding portion 62 are not provided in the base portion 60 of the main base 10 . , the deterioration of the detection accuracy of the rotation angle or rotation amount by the magnetic sensor 50 or the like can be reduced.

Further, the material of the magnetic flux shielding portion 61 and the magnetic flux shielding portion 62 may be any material that can shield unnecessary magnetic flux from the outside, and is not limited to iron or the like. However, by integrally molding the base 60 of the main base 10 and these magnetic flux shielding parts by a method such as casting, the magnetic flux shielding part 61 and the like and the base 60 of the main base 10 are manufactured separately. , the accuracy of the position and dimensions of the magnetic flux shielding portion 61 is improved.

FIG. 41 shows a permanent magnet 9A applicable to absolute encoders 100-1 and 100-2 of the first and second embodiments. FIG. 42 shows a permanent magnet 9B applicable to the absolute encoders 100-1 and 100-2 of the first and second embodiments. FIG. 41 shows a permanent magnet 9A according to the first configuration example. In the permanent magnet 9A, a first magnetic pole portion N with a first polarity and a second magnetic pole portion S with a second polarity different from the first polarity are arranged in the radial direction D1 of the permanent magnet 9A. FIG. 42 shows a permanent magnet 9B according to the second configuration example. In the permanent magnet 9B, the first magnetic pole portion N and the second magnetic pole portion S are arranged in the left half of the figure in the axial direction D2 of the permanent magnet 9B with the center of the permanent magnet 9B as a boundary, while in the right half of the figure. 1, the first magnetic pole portion N and the second magnetic pole portion S are arranged in the axial direction D2 of the permanent magnet 9 in the vertical direction opposite to the left half. The arrow "DM" shown in FIGS. 41 and 42 represents the direction of magnetization.

Both the permanent magnet 9A and the permanent magnet 9B can be used as the permanent magnet 9 of the absolute encoders 100-1 and 100-2 of the first and second embodiments. However, in the permanent magnet 9B, the magnetic field formed by a plurality of lines of magnetic force is distributed so as to expand in the axial direction D2 compared to the magnetic field generated in the permanent magnet 9A. On the other hand, in the permanent magnet 9A, the magnetic field formed by a plurality of lines of magnetic force is distributed so as to expand in the radial direction D1 compared to the magnetic field generated in the permanent magnet 9B. Therefore, when the permanent magnet 9A is used in the absolute encoders 100-1 and 100-2 of the first and second embodiments, the magnetic field generated by the permanent magnet 9A so as to spread outward in the radial direction causes the other magnetic sensors described above to Magnetic interference influenced by magnetic flux is more likely to occur.

Absolute encoders 100-1 and 100-2 according to the respective modifications of Embodiments 1 and 2, when permanent magnet 9B is used as permanent magnet 9, compared to when permanent magnet 9A is used, permanent magnet Leakage magnetic flux generated from 9 is less likely to flow into the magnetic sensor 50 . Also, when the permanent magnet 9B is used as the permanent magnet 8, less leakage magnetic flux generated from the permanent magnet 8 flows into the magnetic sensor 40 than when the permanent magnet 9A is used. As a result, deterioration in detection accuracy of the rotation angle or amount of rotation of the subshaft gear 5 or the main shaft gear 1 can be reduced. In addition, the absolute encoders 100-1 and 100-2 can be further miniaturized by the extent to which the decrease in detection accuracy of the rotation angle or rotation amount can be reduced.

Absolute encoder 100-1 of Embodiment 1 is configured such that the central axes of permanent magnet 8 and magnet holder 6 are aligned with each other, similar to permanent magnet 8 and magnet holder 6 shown in FIG. be. Further, the absolute encoder 100-1 of the first embodiment is configured so that the central axes of the permanent magnet 17 and the second subshaft gear 138 are aligned with each other like the permanent magnet 8 and the magnet holder 6 shown in FIG. configured to Absolute encoder 100-1 of Embodiment 1 is configured such that the respective central axes of permanent magnet 9 and main shaft gear 1 coincide with each other, similar to permanent magnet 9 and main shaft gear 1 shown in FIG. be. With this configuration, the absolute encoder 100-1 of the first embodiment can detect the rotation angle or rotation amount with higher accuracy.

It should be noted that the configuration shown in the above embodiment shows an example of the contents of the present invention, and it is possible to combine it with another known technique, and the configuration can be changed without departing from the gist of the present invention. It is also possible to omit or change part of

1 main shaft gear 1a first cylindrical portion 1b second cylindrical portion 1c communicating portion 1d worm gear portion 1e bottom surface 1f press-fit portion 1g bottom surface 1h magnet holding portion 2 intermediate gear 2a worm wheel portion 2b worm gear portion 2c bearing portion 2d press fitting portion 2e sliding portion 2f bottom surface 2g through hole 2h third worm gear 3 bearing 3a outer ring 3b inner ring 3c side surface 3d side surface 4 shaft 4a one end 4b other end, 5 counter shaft gear, 5-1 upper surface, 5a worm wheel portion, 5b through hole, 6 magnet holder, 6a magnet holding portion, 6b shaft portion, 6c head, 7 bearing, 7a outer ring, 7b inner ring, 8 permanent Magnet 8a Surface 9 Permanent magnet 9A Permanent magnet 9B Permanent magnet 9a Top surface 9b Bottom surface 10 Main base 10-1 Opening 10-1a Wall surface 10-2 Bottom surface 10-3a Wall surface 10a Hole , 10aa recessed portion, 10ab recessed portion, 10ac recessed portion, 10ad mounting surface, 10ae screw hole, 10b hole, 10c contact surface, 10d bearing holder portion, 10da lower portion, 10db upper portion, 10dc inner peripheral surface, 10e leaf spring mounting surface, 10f screw hole, 10g substrate positioning pin, 10g1 base, 10h tip, 10i step, 10j substrate positioning pin, 10j1 base, 10k tip, 10l step, 10m pillar, 10p top surface, 10q pillar, 10r top surface, 10s pillar 10t upper end surface 10u screw hole 10v screw hole 10w screw hole 11 plate spring 11a sliding part 11b mounting part 11c hole 11d base 12 screw 13 substrate mounting screw 14 screw 15 case 15-1 upper surface portion, 15A first side surface portion, 15B second side surface portion, 15C third side surface portion, 15D fourth side surface portion, 15a claw, 15b claw, 15c claw, 15d hole, 15e recess, 15f recess, 15g recess , 15h connector case portion, 15i opening, 16 mounting screw, 17 permanent magnet, 20 substrate, 20-1 lower surface, 20-2 upper surface, 20a positioning hole, 20b positioning hole, 20c hole, 20d hole, 20e hole, 21 microcomputer , 21b table processing unit, 21c rotation amount identification unit, 21e output unit, 21p rotation angle acquisition unit, 21q rotation angle acquisition unit, 22 bidirectional driver, 23 line driver, 24 connector, 40 magnetic sensor, 40a surface, 50 magnetism Sensor 50a surface 60 base 61 magnetic flux shielding portion 61a first plate surface 61b second plate surface 61c first end surface 61d second end surface 61e third end surface 62 magnetic flux shielding portion 62a first plate surface , 62b second plate surface 62c first end surface 62d second end surface 62e third end surface 164 screw 70 wall portion 71 wall portion 72 wall portion 73 side surface 80 wall portion 90 magnetic sensor 100- 1 absolute encoder, 100-2 absolute encoder, 101 main shaft gear, 101a first cylindrical portion, 101b disk portion, 101c worm gear portion, 101d magnet holding portion, 102 first intermediate gear, 102a worm wheel portion, 102b first worm gear portion , 102c base portion, 102d first cylindrical portion, 102e second cylindrical portion, 102f third cylindrical portion, 102g hemispherical projection, 102h second worm gear portion, 102i sliding portion, 105 first countershaft gear, 105a worm wheel portion, 105b bearing portion, 105c disk portion, 105d holding portion, 106 shaft, 110 main base, 110a base portion, 110b support portion, 110c support portion, 107 retaining ring, 108 retaining ring, 110-1 opening, 110-1a wall surface, 111 Leaf spring 111a Sliding portion 111b Mounting portion 115 Case 115a Outer wall portion 115b Outer wall portion 115c Outer wall portion 115d Outer wall portion 116 Lid portion 120 Substrate 121 Microcomputer 121b Table processing portion 121c Rotation amount identification Part 121e Output Part 121p Rotation Angle Acquisition Part 121q Rotation Angle Acquisition Part 121r Rotation Angle Acquisition Part 133 Second Intermediate Gear 133a Worm Wheel Part 133b Bearing Part 133c Overhang Part 133d Fourth Drive Gear Part , 138 second countershaft gear, 138a fourth driven gear portion, 138b bearing portion, 138c projecting portion, 138d magnet holding portion, 139 shaft, 141 support, 200 motor, 201 motor shaft, 202 housing, 202a notch portion , 301 first side, 302 second side, 303 third side, 304 fourth side, 400 connector, 500 magnetic flux shielding portion, 500a first plate surface, 500b second plate surface, 500c first end surface, 500d second end surface , 500e third end surface 501 magnetic flux shielding portion 501a tip surface 502 magnetic flux shielding portion 502a tip surface Td axial direction of intermediate gear 2 or shaft 4;

Claims (8)

a first drive gear that rotates according to the rotation of the main shaft;
a first permanent magnet provided on the tip side of the first drive gear;
a first angle sensor for detecting a rotation angle of the first driving gear corresponding to a change in magnetic flux generated from the first permanent magnet;
a first driven gear having a center axis orthogonal to the center axis of the first drive gear and meshing with the first drive gear;
an intermediate gear formed with the first driven gear and having a predetermined length along an axis of rotation perpendicular to the main shaft;
a second drive gear provided coaxially with the first driven gear and rotating according to the rotation of the first driven gear;
a second driven gear having a central axis perpendicular to the central axis of the first driven gear and meshing with the second drive gear;
a second permanent magnet provided on the tip side of the second driven gear;
a second angle sensor for detecting a rotation angle of the second driven gear corresponding to a change in magnetic flux generated from the second permanent magnet;
a first magnetic flux shielding part surrounding at least part of the periphery of the first drive gear and the second driven gear;
provided at a position facing the second driven gear provided on the side opposite to the first drive gear side of the first driven gear, the magnetic flux generated from at least one of the first permanent magnet and the second permanent magnet; a shielding second magnetic flux shielding part;
a fourth drive gear provided on the opposite side of the first drive gear to the second drive gear and rotating according to the rotation of the first driven gear;
a fourth driven gear meshing with the fourth drive gear;
a third permanent magnet provided on the tip side of the fourth driven gear;
a third angle sensor for detecting a rotation angle of the fourth driven gear corresponding to a change in magnetic flux generated from the third permanent magnet;
with
A plate-shaped member made of a magnetic material is provided between the first angle sensor and a drive source that rotates the main shaft or between the second angle sensor and the drive source,
The first magnetic flux shielding part is provided integrally with the plate-shaped member,
the second driven gear and the fourth driven gear are arranged opposite to each other via the intermediate gear;
The absolute encoder , wherein the rotation axis of the intermediate gear is in a twisted position with respect to the main shaft . The first magnetic flux shielding portion is provided at a position that shields an imaginary line connecting the first permanent magnet and the second permanent magnet and an imaginary line connecting the first permanent magnet and the third permanent magnet. The absolute encoder according to claim 1. 3. The absolute encoder according to claim 2 , further comprising a third magnetic flux shielding portion provided at a position that shields an imaginary line connecting said first permanent magnet and said third permanent magnet. 4. The absolute encoder according to any one of claims 1 to 3 , wherein the position of the tip of the first magnetic flux shielding portion is above the sensor-side end surface of the first permanent magnet. 5. The absolute encoder according to any one of claims 1 to 4 , wherein the position of the tip of the second magnetic flux shielding portion is above the sensor-side end surface of the second permanent magnet. 4. The absolute encoder according to claim 3, wherein the position of the tip of the third magnetic flux shielding portion is above the sensor-side end surface of the third permanent magnet. A plate-shaped member made of a magnetic material is provided between the first angle sensor and a drive source that rotates the main shaft or between the second angle sensor and the drive source,
7. The absolute encoder according to claim 1 , wherein the second magnetic flux shielding portion is provided integrally with the plate-like member. A plate-shaped member made of a magnetic material is provided between the first angle sensor and a drive source that rotates the main shaft or between the second angle sensor and the drive source,
7. The absolute encoder according to claim 3 , wherein the third magnetic flux shielding portion is provided integrally with the plate-like member.

Images