Rotary Encoder

Abstract

To provide a rotary encoder capable of fixedly keeping distance between a spindle magnet and a spindle sensor and stabilizing characteristics of the spindle magnet.SOLUTION: A rotary encoder includes: a spindle 20; a spindle gear 40; a spindle magnet 29; a spindle sensor 151; a spindle sensor board 150; and a support 90 for supporting the spindle sensor board 150. A thermal resistance part made of a hollow cylindrical part 25a is provided between a connection part of one end 504 of a motor shaft in the spindle 20 and a fixed place of the spindle gear 40.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a rotary encoder. [Background technology]

[0002] In the encoder disclosed in Patent Document 1, a main shaft connected to a motor output shaft is housed in a case via a ball bearing, and the motor is fixed to one end of the case and a circuit board is fixed to the other end. A magnet is fixed to the main shaft. A sensor provided on the board detects changes in the magnetic field corresponding to the rotation of the main shaft. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2016-109431 A Summary of the Invention [Problem to be solved by the invention]

[0004] By the way, the magnet on the spindle and the sensor on the circuit board are arranged facing each other with a gap between them, and there is a demand to improve the rotation detection accuracy by keeping the gap between the sensor and magnet constant with high precision. There is also a demand to stabilize the characteristics of the magnet. [Means for solving the problem]

[0005] A rotary encoder for solving the above problem includes a main shaft connected to a motor shaft, a main shaft gear fixed to the main shaft, a main shaft magnet held on the main shaft, a main shaft sensor arranged opposite the main shaft magnet in the axial direction of the main shaft and detecting changes in magnetic field associated with rotation of the main shaft magnet, a main shaft sensor board on which the main shaft sensor is mounted, and a support for supporting the main shaft sensor board, and the rotary encoder has a thermal resistance portion consisting of a hollow cylindrical portion provided between the connection portion of the motor shaft on the main shaft and the fixed point of the main shaft gear.

[0006] According to this, since a thermal resistance part consisting of a hollow cylindrical part is provided between the connecting part of the motor shaft on the main shaft and the fixing part of the main shaft gear, the heat generated in the motor is not easily transferred to the main shaft magnet. Therefore, the distance between the main shaft magnet and the main shaft sensor can be kept constant. Also, the characteristics of the main shaft magnet can be stabilized.

[0007] In the rotary encoder, a convex surface may be formed on the motor mounting surface of the support, and a tip surface of the convex surface may be in contact with the motor. According to this, the motor mounting surface of the support is formed with a convex surface, and the tip surface of the convex surface is in contact with the motor side, so that the heat generated in the motor is not easily transferred to the support, and therefore the distance between the spindle magnet and the spindle sensor can be kept constant, and the characteristics of the spindle magnet can be stabilized.

[0008] In the rotary encoder, it is preferable that a spindle magnet holder for holding the spindle magnet is screwed onto the spindle. According to this, the spindle magnet holder that holds the spindle magnet is screwed together with the spindle, which results in the following advantages over the case where the spindle magnet holder and the spindle are constructed as a single part: By separating the spindle magnet holder and the spindle and screwing them together, heat generated in the motor is less likely to be transmitted to the spindle magnet holder. As a result, the distance between the spindle magnet and the spindle sensor can be kept constant, and the characteristics of the spindle magnet can be stabilized.

[0009] In the above rotary encoder, the support may have a support column extending in an axial direction of the spindle, and the support column may have a positioning surface for the spindle sensor board in the axial direction of the spindle.

[0010] According to this, the spindle sensor board is positioned in the axial direction of the spindle on the positioning surface of the support pillar, so that the distance between the spindle magnet and the spindle sensor can be kept constant compared to when the spindle sensor board is installed on the support via an intermediary object.

[0011] The above rotary encoder may further include a countershaft gear that meshes with the main shaft gear, a countershaft that rotatably supports the countershaft gear, a countershaft magnet held by the countershaft gear, a countershaft sensor arranged opposite the countershaft magnet in the axial direction of the countershaft and detecting a change in magnetic field associated with rotation of the countershaft magnet, and a countershaft sensor board on which the countershaft sensor is mounted, and the support body may support the main shaft sensor board and the countershaft sensor board.

[0012] Here, the above rotary encoder may further include a gear housing case that houses the meshing main shaft gear and countershaft gear, and the support body may have a support pillar extending in the axial direction of the main shaft, and the support pillar may have a positioning surface for the main shaft sensor board, a positioning surface for the gear housing case, and a positioning surface for the countershaft sensor board, at different positions in the axial direction of the main shaft.

[0013] According to this, the main shaft sensor board, the gear housing box, and the counter shaft sensor board are positioned on the positioning surface of the support column in the axial direction of the main shaft. Meanwhile, since the counter shaft magnet is held by the counter shaft gear, the position of the counter shaft magnet is determined by the position of the gear housing box. Therefore, the distance between the main shaft magnet and the main shaft sensor, and the distance between the counter shaft magnet and the counter shaft sensor can be kept constant. Effect of the Invention

[0014] According to the present invention, the distance between the spindle magnet and the spindle sensor can be kept constant, and the characteristics of the spindle magnet can be stabilized. [Brief description of the drawings]

[0015] [Figure 1] FIG. 2 is a perspective view showing an electric actuator and a rotary encoder. [Diagram 2] FIG. 2 is an exploded perspective view of the electric actuator and the rotary encoder. [Diagram 3] FIG. 2 is a cross-sectional view of a rotary encoder. [Figure 4] FIG. 2 is an exploded perspective view of the electric actuator and the rotary encoder. [Diagram 5] FIG. 2 is a perspective view showing an electric actuator and a rotary encoder. [Figure 6] FIG. [Figure 7] FIG. [Figure 8] FIG. 2 is a perspective view showing a main shaft gear, a first countershaft gear, and a second countershaft gear. [Figure 9] FIG. 2 is a perspective view showing a main shaft gear, a first countershaft gear, and a second countershaft gear. [Figure 10] FIG. 2 is a perspective view of a main body of the gear housing box. [Figure 11] FIG. 2 is a perspective view of a main body of the gear housing box. [Figure 12] FIG. 2 is a perspective view showing a main body of a gear housing box, a main shaft gear, a first countershaft gear, and a second countershaft gear. [Figure 13]FIG. 4 is a perspective view of a cover of the gear housing box. [Figure 14] FIG. 4 is a perspective view of a cover of the gear housing box. [Figure 15] FIG. 2 is a plan view showing a main body of the gear accommodating box, a main shaft gear, a first countershaft gear, and a second countershaft gear. [Figure 16] FIG. 2 is a plan view showing a main body of the gear accommodating box, a main shaft gear, a first countershaft gear, and a second countershaft gear, for illustrating the flow of grease. [Figure 17] FIG. 11 is a plan view showing a main body, a main shaft gear, and a countershaft gear of a gear housing box according to another example. [Figure 18] FIG. 11 is a plan view showing a main body, a main shaft gear, and a countershaft gear of a gear housing box according to another example. [Figure 19] FIG. 11 is a partial cross-sectional view of a rotary encoder according to another embodiment. [Figure 20] FIG. 11 is a partial cross-sectional view of a rotary encoder according to another embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, an embodiment of an electric actuator will be described with reference to the drawings. As shown in Figs. 1 and 2, an electric actuator 500 has a motor 501. The motor 501 is equipped with a stator 502 and a bearing holder 503. One end 504 of a motor shaft protrudes vertically from the bearing holder 503. The other end of the motor shaft protrudes on the opposite side of the bearing holder 503 and is connected to a rotating part of an actuator (not shown) to constitute an electric actuator driven by the motor. The axial direction of one end 504 of the motor shaft is defined as the X direction, and a plane perpendicular to the X direction is defined as the YZ plane. A rotary encoder 10 is provided on the bearing holder 503 from which one end 504 of the motor shaft protrudes.

[0017] One surface 503a of the bearing holder 503 serves as a reference surface when installing the rotary encoder. The mounting positions of each component in the X, Y, and Z directions are determined based on the one surface 503a of the bearing holder 503.

[0018] The rotary encoder 10 is for detecting the position of the electric actuator 500 , that is, the rotational position of the motor 501 . <Overall configuration of the rotary encoder 10> The rotary encoder 10 is an absolute rotary encoder. As shown in Fig. 2 and Fig. 3, the rotary encoder 10 includes a rod-shaped main shaft 20, a main shaft gear 40, a first counter shaft 50 formed of a round pin, a first counter shaft gear 61, a second counter shaft 70 formed of a round pin, and a second counter shaft gear 81. The rotary encoder 10 also includes a support 90, a gear housing box 110 formed of a main body 120 and a cover 140, a main shaft sensor board 150, a counter shaft sensor board 160, and a shield cover 170. The rotary encoder 10 also includes a main shaft magnet 29, counter shaft magnets 181, 191, a main shaft sensor 151, and counter shaft sensors 161, 162.

[0019] The rotary encoder 10 can measure the absolute rotation speed of the motor 501 by utilizing the phase difference between the main shaft gear 40, the first countershaft gear 61, and the second countershaft gear 81. The main shaft 20 is arranged coaxially in the X direction at the tip side of one end 504 of the motor shaft. The main shaft 20, the first countershaft 50, and the second countershaft 70 have their axes extending parallel to the X direction and are arranged spaced apart in the Y direction. The main shaft sensor board 150 and the countershaft sensor board 160 are arranged on a plane perpendicular to the axial direction of the main shaft 20, the first countershaft 50, and the second countershaft 70.

[0020] Three gears 40, 61, 81 are housed in the gear accommodating box 110. The X direction is the tooth width direction of each gear 40, 61, 81 and extends in the YZ plane. A sensor board 160 having sensors 161, 162 mounted thereon is disposed closer to the motor than the gear accommodating box 110 in the X direction, and a sensor board 150 having a sensor 151 mounted thereon is disposed closer to the motor than the gear accommodating box 110. The sensor boards 150, 160 and the gear accommodating box 110 are supported by a support body 90.

[0021] <Configuration of spindle-related parts> As shown in FIG. 3 and FIG. 4, the main shaft 20 is generally cylindrical. The main shaft 20 has a large diameter portion 21 on the motor side, which is the base end side, and a small diameter portion 22 on the opposite side to the motor side, which is the tip end side. The main shaft 20 has a motor shaft insertion hole 23 with a large diameter formed on the base end side, and a female screw hole 24 with a small diameter formed on the tip end side. The periphery of the motor shaft insertion hole 23 in the small diameter portion 22 is a thin cylindrical portion 25a. One end 504 of a motor shaft of a motor 501 is inserted into the motor shaft insertion hole 23 of the main shaft 20 with their axes aligned. The main shaft 20 is fixed to the one end 504 of the motor shaft by set screws Sc1 and Sc2 that are screwed in from a direction perpendicular to the axial direction. As a result, the main shaft 20 is connected to the one end 504 of the motor shaft. Then, the main shaft 20 rotates integrally with the one end 504 of the motor shaft as the one end 504 of the motor shaft rotates.

[0022] The main shaft gear 40 is a spur gear. A through hole 41 is formed in the center of the main shaft gear 40. The through hole 41 of the main shaft gear 40 is inserted into the outer circumferential surface of the tip end of the main shaft 20, which is on the side opposite the motor, in a fitted state.

[0023] A magnet holder 25 is screwed into the female screw hole 24 of the main shaft 20. The magnet holder 25 has a main body 26, a male screw shaft 27, and a magnet accommodating recess 28. The male screw shaft 27 protrudes from the main body 26 toward the motor side in the X direction. A circular magnet accommodating recess 28 is formed on the end face of the main body 26 on the opposite side to the motor. The magnet holder 25 is fixed to the main shaft 20 by screwing the male screw shaft 27 of the magnet holder 25 into the female screw hole 24 of the main shaft 20. The magnet holder 25 rotates integrally with the main shaft 20 as the main shaft 20 rotates. The main shaft gear 40 is fixed to the main shaft 20 by screwing the magnet holder 25 to the main shaft 20. The main shaft gear 40 rotates integrally with the main shaft 20 as the main shaft 20 rotates.

[0024] As shown in FIG. 3, the magnet holder 25 protrudes from the main shaft gear 40 toward the motor side and toward the opposite side to the motor in the X direction. In the magnet accommodating recess 28 of the magnet holder 25, the spindle magnet 29 and the spindle magnet magnetic shielding member 30 are arranged so as to overlap in the X direction. The spindle magnet 29 held by the spindle 20 is disk-shaped. The spindle magnet 29 can be appropriately adapted to have two poles magnetized or four poles magnetized on both sides. The spindle magnet magnetic shielding member 30 is disk-shaped. The spindle magnet 29 and the spindle magnet magnetic shielding member 30 have the same diameter. In the magnet accommodating recess 28, the spindle magnet 29 is on the opening side, which is the side opposite to the motor, and the spindle magnet magnetic shielding member 30 is on the bottom side, which is the side of the motor, and are adhered and fixed to the magnet holder 25 in a stacked and closely contacted state. The spindle magnet 29 is made of a hard magnetic material. The spindle magnet magnetic shielding member 30 is made of a soft magnetic material.

[0025] In this manner, the main shaft gear 40 is fixed to the main shaft 20 by screwing the magnet holder 25, to which the magnet 29 and the main shaft magnet magnetic shielding member 30 are fixed, to the main shaft 20 fixed to one end 504 of the motor shaft. Also, the main shaft magnet 29 is adhesively fixed to the magnet holder 25. The main shaft gear 40 is fixed by screwing the magnet holder 25 to the main shaft 20.

[0026] As shown in FIG. 3, in the motor shaft insertion hole 23 at the center of the main shaft 20, a gap V1 is formed between the tip surface of one end 504 of the motor shaft and the bottom of the motor shaft insertion hole 23. In detail, when the one end 504 of the motor shaft is press-fitted into the motor shaft insertion hole 23 of the main shaft 20, the one end 504 of the motor shaft is not inserted until the tip surface of the one end 504 of the motor shaft contacts the bottom of the motor shaft insertion hole 23, but a gap V1 is formed between the tip surface of the one end 504 of the motor shaft and the bottom of the motor shaft insertion hole 23. As a result, a large heat resistance part is formed in a thin part of the outer periphery of the gap V1 in the main shaft 20. In other words, the length of the part on the tip side of the one end 504 of the motor shaft in the motor shaft insertion hole 23 is increased to increase the length of the cylindrical part 25a with a small cross-sectional area. As a result, a heat resistance part consisting of the hollow cylindrical part 25a is provided between the connecting part of the one end 504 of the motor shaft in the main shaft 20 and the fixing part of the main shaft gear 40.

[0027] 3, a screw portion is formed between the female screw hole 24 of the spindle 20 and the male screw shaft 27 of the magnet holder 25. This forms a large thermal resistance portion between the magnet holder 25 and the spindle 20. In addition, the tip surface of the spindle 20 on the side opposite to the motor and the magnet holder 25 are in surface contact. This forms a large thermal resistance portion between the magnet holder 25 and the spindle 20.

[0028] As shown in Fig. 5, a first countershaft gear 61 meshes with the mainshaft gear 40. The first countershaft gear 61 is a spur gear. A second countershaft gear 81 meshes with the mainshaft gear 40. The second countershaft gear 81 is a spur gear. The mainshaft gear 40, the first countershaft gear 61, and the second countershaft gear 81 are arranged side by side with the mainshaft gear 40 located in the middle in the Y direction.

[0029] Regarding the number of teeth of the main shaft gear 40, the number of teeth of the first countershaft gear 61, and the number of teeth of the second countershaft gear 81, for example, the number of teeth of the main shaft gear 40 is "21," the number of teeth of the first countershaft gear 61 is "23," and the number of teeth of the second countershaft gear 81 is "25."

[0030] 15, the main shaft gear 40, the first countershaft gear 61, and the second countershaft gear 81 are housed inside a gear accommodating box 110. The inside of the gear accommodating box 110 is filled with grease Gr1.

[0031] <Configuration of the support 90> As shown in Figs. 6 and 7, the support 90 is made of metal, and is made of a non-magnetic and conductive material. The support 90 is made of die casting. The support 90 has a square base portion 91 extending in the YZ plane, and a support column 92 extending in the X direction from the base portion 91. The support 90 is processed by metal processing, so that the dimensional accuracy is high. A circular through hole 93 is formed in the center of the square base portion 91. As shown in Fig. 3, the main shaft 20 passes through the circular through hole 93.

[0032] As shown in Figs. 6 and 7, a support pillar 92 is erected on the outer periphery of the square base portion 91. Three through holes 94 are formed in the square base portion 91 of the support 90. The through holes 94 are elongated holes. As shown in Fig. 2, mounting screws Sc3, Sc4, and Sc5 are screwed into female screw holes 505, 506, and 507 of a bearing holder 503 of the motor through the through holes 94, so that the support 90 is fixed to the bearing holder 503 of the motor in alignment with the axis of one end 504 of the motor shaft. In addition, two through holes 95 are formed in the square base portion 91.

[0033] As shown in Fig. 7, convex surfaces 96 are formed around the through holes 94, 95 on the back surface of the square base portion 91, i.e., the surface on the motor side. Convex surfaces 97 are also formed at the corners on the back surface of the square base portion 91. The tip surfaces of the convex surfaces 96, 97 come into contact with one surface 503a of the bearing holder 503 of the motor, as shown in Fig. 3. The convex surface 97 is provided to balance the support body 90 so that it does not tilt.

[0034] Since the sensor boards 150, 160 and the gear housing box 110 are directly supported independently on the support body 90, the positions of the sensors 151, 161, 162 and the positions of the magnets 29, 181, 191 can be kept constant. Specifically, the support body 90 is machined to determine its height in the X direction and its dimensions in the planar direction based on the central through-hole 93 and the bottom surface on which the motor 501 is mounted, and machined surfaces 98, 99, 100 are provided. The machined surfaces 98, 99, 100 are used to determine the positions of the two sensor boards 150, 160 and the resin gear housing box 110. The machined surfaces 98, 99, 100 will be described later.

[0035] The support 90 is attached to the motor 501 so that the motor shaft end 504 and the central through-hole 93 are aligned and coaxial. The spindle 20 is directly fixed to one end 504 of the motor shaft so that the distance from the motor end face is constant. Since the distance of the spindle 20 from one face 503a of the bearing holder 503, which is the motor end face, is determined, the support 90 also determines the height of the machining faces 98, 99, 100 in the X direction.

[0036] As shown in FIGS. 3 and 7, the convex surfaces 96, 97 form a large thermal resistance portion between the support 90 and one surface 503a of the bearing holder 503 of the motor. As shown in Fig. 6, countershaft sensor board positioning machined surfaces 98 are formed in three places at a low position in the X direction on the support 92 as positioning surfaces for the countershaft sensor board 160. The countershaft sensor board 160 is disposed so as to contact the countershaft sensor board positioning machined surfaces 98 as shown in Fig. 3. This determines the position of the countershaft sensor board 160 in the X direction. As shown in Fig. 6, protrusions 101 with which the outer peripheral end face of the countershaft sensor board 160 comes into contact are formed on the countershaft sensor board positioning machined surfaces 98, thereby determining the position of the countershaft sensor board 160 in the YZ plane. The countershaft sensor board 160 is fixed to the support 90 by mounting screws Sc6 and Sc7 as shown in Fig. 2.

[0037] As shown in Fig. 6, at a position higher than the countershaft sensor board positioning processed surface 98 in the X direction on the support 92, two box body positioning processed surfaces 99 are formed as positioning surfaces for the gear accommodating box 110. As shown in Fig. 3, the gear accommodating box 110 is arranged to contact the box body positioning processed surfaces 99. This determines the position of the gear accommodating box 110 in the X direction. As shown in Fig. 6, a protrusion 102 with which the outer peripheral end face of the gear accommodating box 110 comes into contact is formed on the box body positioning processed surfaces 99, and the position of the gear accommodating box 110 in the YZ plane is determined. As shown in Fig. 2, the gear accommodating box 110 is fixed to the support 90 by mounting screws Sc8 and Sc9.

[0038] As shown in Fig. 6, at a position higher than the processed surface 99 for positioning the box body in the X direction on the support 92, processed surfaces 100 for positioning the spindle sensor board are formed in two places as a positioning surface for the spindle sensor board 150. As shown in Fig. 3, the spindle sensor board 150 is arranged so as to contact the processed surface 100 for positioning the spindle sensor board. This determines the position of the spindle sensor board 150 in the X direction. As shown in Fig. 6, protrusions 103 with which the outer peripheral end face of the spindle sensor board 150 comes into contact are formed on the processed surface 100 for positioning the spindle sensor board, and the position of the spindle sensor board 150 in the YZ plane is determined. The spindle sensor board 150 is fixed to the support 90 by mounting screws Sc10 and Sc11 as shown in Fig. 2.

[0039] Thus, the support 90 has a support pillar 92 extending in the axial direction of the main shaft 20. The support pillar 92 has, at different positions in the axial direction of the main shaft 20, a machined surface 98 serving as a positioning surface for the main shaft sensor board 150, a machined surface 99 serving as a positioning surface for the gear housing case 110, and a machined surface 100 serving as a positioning surface for the countershaft sensor board 160.

[0040] <Configuration of countershaft related parts> 3 and 9, the gear body 60 is composed of a first countershaft gear 61 and a magnet holding portion 62, which are molded as one piece. The magnet holding portion 62 is for holding the first countershaft magnet 181 while holding the first countershaft gear 61. The first countershaft gear 61 and the magnet holding portion 62 are molded as one piece on the same axis.

[0041] The magnet holding portion 62 extends in the X direction. A first countershaft gear 61 is formed on the outer periphery of one end of the magnet holding portion 62 on the side opposite the motor. As shown in Figs. 3 and 8, a circular recess 64 is formed on one end face of the magnet holding portion 62 on the side opposite the motor. A circular protrusion 65 is formed in the center of the recess 64 on the one end face of the magnet holding portion 62. A pin press-in hole 66 is formed in the center of the circular protrusion 65 as a shaft fixing hole. The tip of the pin press-in hole 66 has a small diameter and penetrates the magnet holding portion 62. As shown in Figs. 3 and 9, a circular recess 67 is formed on the other end face of the magnet holding portion 62 on the motor side. The recess 67 is for holding the first countershaft magnet 181. The pin press-in hole 66 opens at the bottom of the recess 67. The first countershaft 50 is inserted into the pin press-in hole 66 as shown in Fig. 3. 3 and 10, the first countershaft (pin) 50 is press-fitted and fixed into the pin insertion hole 125 of the main body 120 of the gear accommodating box 110. The first countershaft 50 supports a first countershaft gear 61 for rotation.

[0042] 3 and 9, the gear body 80 is composed of a second countershaft gear 81 and a magnet holder 82, which are molded as a single unit. The magnet holder 82 is for holding the second countershaft magnet 191 while holding the second countershaft gear 81. The second countershaft gear 81 and the magnet holder 82 are molded as a single unit on the same axis.

[0043] The magnet holding portion 82 extends in the X direction. A second countershaft gear 81 is formed on the outer periphery of one end of the magnet holding portion 82 on the side opposite the motor. As shown in Figs. 3 and 8, a circular recess 84 is formed on one end face of the magnet holding portion 82 on the side opposite the motor. A circular protrusion 85 is formed in the center of the recess 84 on the one end face of the magnet holding portion 82. A pin press-in hole 86 is formed in the center of the circular protrusion 85 as a shaft fixing hole. The tip of the pin press-in hole 86 has a small diameter and penetrates the magnet holding portion 82. As shown in Figs. 3 and 9, a circular recess 87 is formed on the other end face of the magnet holding portion 82 on the motor side. The recess 87 is for holding the second countershaft magnet 191. The pin press-in hole 86 opens at the bottom of the recess 87. The second countershaft 70 is inserted into the pin press-in hole 86 as shown in Fig. 3. 3 and 10, the second countershaft (pin) 70 is press-fitted and fixed into the pin insertion hole 126 of the main body 120 of the gear accommodating box 110. The second countershaft 70 supports a second countershaft gear 81 for rotation.

[0044] <Configuration of parts related to the gear housing body 110> As shown in FIG. 2, the gear housing box 110 is composed of a main body 120 on the side opposite the motor in the X direction and a cover 140 on the motor side. As shown in FIG. 10 and FIG. 11, the main body 120 has a flat plate portion 121 extending in the YZ plane. A through hole 122 is formed in the center of the flat plate portion 121. As shown in FIG. 11, on the surface of the flat plate portion 121 that corresponds to the outer surface of the gear housing box 110, two cylindrical portions 123, 124 are protruded around the through hole 122 at 180° intervals with the through hole 122 as the center. One of the cylindrical portions 123 is formed with a pin insertion hole 125. This pin insertion hole 125 opens to the inner surface of the gear housing box 110. As shown in FIG. 3, the first countershaft 50 is press-fitted into the pin insertion hole 125.

[0045] As shown in Fig. 11, a pin insertion hole 126 is formed in the other cylindrical portion 124. This pin insertion hole 126 opens to the inner surface of the gear accommodating box 110. As shown in Fig. 3, the second countershaft 70 is press-fitted into the pin insertion hole 126.

[0046] As shown in FIG. 11, on one surface of the flat plate portion 121 on the side opposite to the motor, a convex portion 127 protrudes on the outer peripheral portion. As shown in FIG. 10, on the surface of the flat plate portion 121 corresponding to the inner surface of the gear housing 110, arc-shaped convex portions 128a and 128b project around the through hole 122. As shown in FIG. 12, the main shaft gear 40 is disposed inside the arc-shaped convex portions 128a and 128b. That is, the convex portions 128a and 128b form a part of a circle centered on the through hole 122, and protrude slightly larger than the tooth width of the main shaft gear 40 in the X direction. The inner diameter of the arc-shaped convex portions 128a and 128b is slightly larger than the diameter of the tooth crest of the main shaft gear 40. A rotational clearance is formed between the teeth of the main shaft gear 40 and the convex portions 128a and 128b of the gear housing 110. As shown in FIG. 15, a grease reservoir 146 is formed between the inner diameter surface of the arc-shaped convex portions 128a and 128b and the tooth valleys of the main shaft gear 40.

[0047] As shown in FIG. 10, on the surface of the flat plate portion 121 corresponding to the inner surface of the gear housing 110, an arc-shaped convex portion 129 projects around one pin insertion hole 125 (the first sub-shaft 50). As shown in FIG. 12, the first sub-shaft gear 61 is disposed inside the arc-shaped convex portion 129. That is, the convex portion 129 forms a part of a circle centered on the pin insertion hole 125 (the first sub-shaft 50), and protrudes slightly larger than the tooth width of the first sub-shaft gear 61 in the X direction. The inner diameter of the arc-shaped convex portion 129 is slightly larger than the diameter of the tooth crest of the first sub-shaft gear 61. A rotational clearance is formed between the teeth of the first sub-shaft gear 61 and the convex portion 129 of the gear housing 110. As shown in FIG. 15, a grease reservoir 147 is formed between the inner diameter surface of the arc-shaped convex portion 129 and the tooth valleys of the first sub-shaft gear 61.

[0048] As shown in FIG. 10, on the surface of the flat plate portion 121 corresponding to the inner surface of the gear housing box 110, an arc-shaped convex portion 130 is provided around the other pin insertion hole 126 (second countershaft 70). The second countershaft gear 81 is disposed inside the arc-shaped convex portion 130 as shown in FIG. 12. That is, the convex portion 130 forms a part of a circle centered on the pin insertion hole 126 (second countershaft 70) and protrudes slightly larger than the tooth width of the second countershaft gear 81 in the X direction. The inner diameter of the arc-shaped convex portion 130 is slightly larger than the diameter of the crest of the tooth of the second countershaft gear 81. A rotation gap is formed between the tooth of the second countershaft gear 81 and the convex portion 130 of the gear housing box 110. A grease reservoir 148 is formed between the inner diameter surface of the arc-shaped convex portion 130 and the tooth valley of the second countershaft gear 81 as shown in FIG. 15.

[0049] 10, the interiors of the three arc-shaped protrusions 128a, 128b, 129, and 130 formed side by side in the Y direction are in communication with each other. That is, the arc-shaped protrusions 128a, 128b formed around the through hole 122 and the arc-shaped protrusion 129 formed around one pin insertion hole 125 (first countershaft 50) are partially overlapped with each other, so that the interiors of the arc-shaped protrusions 128a, 128b and the interior of the arc-shaped protrusion 129 are in communication with each other. Similarly, the arc-shaped protrusions 128a, 128b formed around the through hole 122 and the arc-shaped protrusion 130 formed around the other pin insertion hole 126 (second countershaft 70) are partially overlapped with each other, so that the interiors of the arc-shaped protrusions 128a, 128b and the interior of the arc-shaped protrusion 130 are in communication with each other.

[0050] In this manner, the first countershaft gear 61 and the second countershaft gear 81 are arranged on either side of the mainshaft gear 40 inside the gear housing case 110 as shown in FIG. As shown in FIG. 10, on the surface of the flat plate portion 121 corresponding to the inner surface of the gear housing box 110, a first grease circulation path forming convex portion 131 and a second grease circulation path forming convex portion 132 are formed on the outer diameter side of the convex portions 128a, 128b around the through hole 122. A first grease circulation path R1 is formed between the convex portion 128a around the through hole 122 and the first grease circulation path forming convex portion 131. One end of the first grease circulation path R1 opens at a connection portion between the arc-shaped convex portion 128a and the arc-shaped convex portion 129 to form an opening OP1. The other end of the first grease circulation path R1 opens at a connection portion between the arc-shaped convex portion 128a and the arc-shaped convex portion 130 to form an opening OP2. In addition, as shown in FIG. 10, a second grease circulation path R2 is formed between the convex portion 128b around the through hole 122 and the second grease circulation path forming convex portion 132. One end of the second grease circulation path R2 opens to a connection portion between the arc-shaped protrusion 128b and the arc-shaped protrusion 129 to form an opening OP3. The other end of the second grease circulation path R2 opens to a connection portion between the arc-shaped protrusion 128b and the arc-shaped protrusion 130 to form an opening OP4.

[0051] As shown in FIG. 10, on a surface of the flat plate portion 121 corresponding to the inner surface of the gear housing box 110, a circular protrusion 133 is provided around one of the pin insertion holes 125 (first countershaft 50) to protrude. This circular protrusion 133 is formed inside the arc-shaped protrusion 129. The amount of protrusion of this circular protrusion 133 in the X direction is smaller than the amount of protrusion of the arc-shaped protrusion 129 in the X direction. Similarly, on a surface of the flat plate portion 121 corresponding to the inner surface of the gear housing box 110, a circular protrusion 134 is provided around the other pin insertion hole 126 (second countershaft 70). This circular protrusion 134 is formed inside the arc-shaped protrusion 130. The amount of protrusion of this circular protrusion 134 in the X direction is smaller than the amount of protrusion of the arc-shaped protrusion 130 in the X direction.

[0052] As shown in FIG. 10, a convex portion 135 protrudes from the outer periphery of the surface of the flat plate portion 121 that corresponds to the inner surface of the gear accommodating box 110 . 13 and 14, the cover 140 of the gear accommodating box 110 has a flat plate portion 141 extending in the YZ plane. Three through holes 142, 143, and 144 are formed in the flat plate portion 141 and aligned in the Y direction. As shown in Fig. 14, on the surface of the flat plate portion 141 that corresponds to the inner surface of the gear accommodating box 110, a circular protrusion 145 is formed on the inner diameter portion of each of the through holes 142, 143, and 144.

[0053] The cover 140 is disposed on the side of the flat plate portion 121 that corresponds to the inner surface of the gear accommodating box 110. In this state, as shown in FIG. 2, mounting screws Sc8 and Sc9 that penetrate the main body 120 and the cover 140 are screwed into the support body 90, whereby the gear accommodating box 110 is fixed to the support body 90.

[0054] As shown in Fig. 3, the outer periphery and tooth width direction of the gears 40, 61, 81, excluding the magnet mounting end, are surrounded by the gear housing box 110 with a gap formed. The countershaft gears 61, 81 have their tooth width sandwiched between the gear housing box 110 and their rotation centers are positioned by the countershafts 50, 70. Only the countershafts 50, 70 require bearing lubrication. The gears 40, 61, 81 and the gear housing box 110 are made of resin with the same linear expansion coefficient.

[0055] As shown in Fig. 15, the gears 40, 61, and 81 in the gear housing box 110 shown in Fig. 12 are filled with grease Gr1. The grease circulation paths R1 and R2 are also filled with grease Gr1, so the amount of grease enclosed increases. At this time, the grease circulation paths R1 and R2 connect the grease discharge portion and the grease intake portion of the meshing portion that are generated when the gears 40, 61, and 81 rotate, preventing fluctuations in grease pressure when the gears 40, 61, and 81 rotate and suppressing the generation of outflow pressure. Furthermore, the outflow of grease Gr1 is suppressed by increasing the contact area of ​​grease Gr1 and the surface tension due to the gap.

[0056] As shown in FIG. 3, the main shaft 20 passes through the central through hole 142 of the three through holes 142, 143, and 144 in the cover 140 of the gear accommodating box 110. A small gap is formed between the through hole 142 and the main shaft 20. The magnet holding part 62 passes through the through hole 143. A small gap is formed between the through hole 143 and the magnet holding part 62. In other words, the cylindrical outer part of the magnet holding part 62 forms a gap with the gear accommodating box 110 to prevent the grease from leaking out. The magnet holding part 82 passes through the through hole 144. A small gap is formed between the through hole 144 and the magnet holding part 82. In other words, the cylindrical outer part of the magnet holding part 82 forms a gap with the gear accommodating box 110 to prevent the grease from leaking out.

[0057] 3, a magnet holder 25 for the main shaft is disposed in a through hole 122 of a main body 120 of the gear housing box 110. A small gap is formed between the through hole 122 and the magnet holder 25.

[0058] In the X direction, the tip of the protrusion 65 of the magnet holding part 62 comes into contact with the flat plate part 121 of the main body 120 of the gear accommodating box 110. Also, in the X direction, the end face of the first countershaft gear 61 comes into contact with the tip face of the protrusion 145 of the cover 140. This determines the axial positions of the first countershaft gear 61 and the magnet holding part 62. At this time, the protrusion 133 of the main body 120 of the gear accommodating box 110 is placed in the recess 64 of the magnet holding part 62. Since the recess 64 and the protrusion 133 are spaced apart by a certain distance in the X and Y directions, grease Gr1 is filled between the recess 64 and the protrusion 133.

[0059] Similarly, the tip of the protrusion 85 of the magnet holding portion 82 comes into contact with the flat plate portion 121 of the main body 120 of the gear accommodating box 110. Also, the end face of the second countershaft gear 81 comes into contact with the tip face of the protrusion 145 of the cover 140 in the X direction. This determines the axial positions of the second countershaft gear 81 and the magnet holding portion 82. At this time, the protrusion 134 of the main body 120 of the gear accommodating box 110 is disposed in the recess 84 of the magnet holding portion 82. Since the recess 84 and the protrusion 134 are spaced apart by a certain distance in the X and Y directions, grease Gr1 is filled between the recess 84 and the protrusion 134.

[0060] The opening of the main body 120 shown in FIG. 10 is covered by a flat cover 140 shown in FIG. As shown in FIG. 3, one end of the first countershaft 50 is press-fitted into a pin insertion hole 125 of the main body 120 of the gear accommodating box 110. The magnet holder 62 faces the other end of the first countershaft 50. The other end of the first countershaft 50 is slidably arranged in a pin press-fit hole 66 of the magnet holder 62. The first countershaft 50 is slidably and rotatably inserted into the pin press-fit hole 66 to form a sliding bearing. Similarly, one end of the second countershaft 70 is press-fitted into a pin insertion hole 126 of the main body 120 of the gear accommodating box 110. The magnet holder 82 faces the other end of the second countershaft 70. The other end of the second countershaft 70 is slidably arranged in a pin press-fit hole 86 of the magnet holder 82. The second countershaft 70 is slidably and rotatably inserted into the pin press-fit hole 86 to form a sliding bearing.

[0061] In this manner, the gear housing box 110 positions the main shaft gear 40 and the counter shaft gears 61, 81 in the axial direction by the tooth width, and supports the counter shaft gears 61, 81 rotatably. As shown in FIG. 3, the first countershaft 50 is fixed to the gear housing box 110 by press-fitting toward the motor side in the X direction, and the gear 61 is rotatably inserted on the countershaft 50. The magnet holder 180 is fixed to the circular recess 67 of the magnet holder 62 by press-fitting. At this time, a gap Sp1 is provided between the magnet holder 180 and the bottom of the recess 67. Grease Gr2 is stored in this gap Sp1. The gap Sp1 in which the grease is stored is a grease reservoir larger than the diameter of the countershaft 50. In other words, the gap Sp1 is set to be left at the bottom of the recess 67 when the magnet holder 180 is inserted into the recess 67, and is used as a reservoir for the grease Gr2. The pin press-fit hole 66 faces this portion, making it possible to supply grease.

[0062] The magnet holder 180 rotates integrally with the magnet holder 62 as it rotates. The magnet holder 180 is cylindrical with a bottom. Inside the cylindrical magnet holder 180 with a bottom, the first countershaft magnet 181 and the first countershaft magnet shielding member 182 are arranged so as to overlap in the X direction. The first countershaft magnet 181 held by the first countershaft gear 61 is disk-shaped. The first countershaft magnet 181 can be appropriately adapted to two-pole magnetization or double-sided four-pole magnetization. The first countershaft magnet shielding member 182 is disk-shaped. The first countershaft magnet 181 and the first countershaft magnet shielding member 182 have the same diameter. Inside the cylindrical magnet holder 180 with a bottom, the first countershaft magnet 181 is bonded and fixed to the magnet holder 180 in a state of being stacked and in close contact with each other so that the first countershaft magnet 181 is on the opening side and the first countershaft magnet shielding member 182 is on the bottom. The first countershaft magnet 181 is made of a hard magnetic material, and the first countershaft magnet magnetic shielding member 182 is made of a soft magnetic material.

[0063] Similarly, in the X direction, the second countershaft 70 is fixed to the gear housing box 110 by press-fitting toward the motor side, and the gear 81 is rotatably inserted on the countershaft 70. The magnet holder 190 is fixed to the circular recess 87 of the magnet holder 82 by press-fitting. At this time, a gap Sp2 is provided between the magnet holder 190 and the bottom of the recess 87. Grease Gr3 is stored in this gap Sp2. The gap Sp2 in which the grease is stored is a grease reservoir larger than the diameter of the countershaft 70. In other words, the gap Sp2 is set to be left at the bottom of the recess 87 when the magnet holder 190 is inserted into the recess 87, and is used as a reservoir for the grease Gr3. The pin press-fit hole 86 faces this portion, making it possible to supply grease.

[0064] The magnet holder 190 rotates integrally with the magnet holder 82 as it rotates. The magnet holder 190 is cylindrical with a bottom. Inside the cylindrical magnet holder 190, the second countershaft magnet 191 and the second countershaft magnet shielding member 192 are arranged so as to overlap in the X direction. The second countershaft magnet 191 held by the second countershaft gear 81 is disk-shaped. The second countershaft magnet 191 can be appropriately adapted to two-pole magnetization or double-sided four-pole magnetization. The second countershaft magnet shielding member 192 is disk-shaped. The second countershaft magnet 191 and the second countershaft magnet shielding member 192 have the same diameter. Inside the cylindrical magnet holder 190, the second countershaft magnet 191 is bonded and fixed to the magnet holder 190 in a state of being stacked and in close contact with each other so that the second countershaft magnet 191 is on the opening side and the second countershaft magnet shielding member 192 is on the bottom. The second countershaft magnet 191 is made of a hard magnetic material, and the second countershaft magnet magnetic shielding member 192 is made of a soft magnetic material.

[0065] The diameter of the main shaft magnet 29 is, for example, 5 mm, and the diameter of the counter shaft magnets 181, 191 is, for example, 4 mm. The diameter of the main shaft magnet 29 is made large so as to generate a stable magnetic field. The thickness of the main shaft magnet magnetic shielding member 30 is, for example, 0.5 mm. The thickness of the counter shaft magnet magnetic shielding members 182, 192 is, for example, 1 mm. Thus, the thickness of the counter shaft magnet magnetic shielding members 182, 192 in the tooth width direction is thicker than the thickness of the main shaft magnet magnetic shielding member 30 in the tooth width direction.

[0066] <Configuration of sensor-related parts> As shown in Fig. 3, the spindle sensor board 150 is arranged to face the gear accommodating box 110 on the side opposite the motor of the gear accommodating box 110 in the X direction. A spindle sensor 151 is mounted on the spindle sensor board 150. The spindle sensor 151 is arranged to face the spindle magnet 29 across a gap. The spindle sensor 151 is arranged to face the spindle magnet 29 in the axial direction of the spindle 20. The spindle sensor 151 detects a change in the magnetic field accompanying the rotation of the spindle magnet 29.

[0067] A countershaft sensor board 160 is disposed between the support 90 and the gear housing box 110 in the X direction so as to face the gear housing box 110. A first countershaft sensor 161 and a second countershaft sensor 162 are mounted on the countershaft sensor board 160. The first countershaft sensor 161 is disposed facing the first countershaft magnet 181 across a gap. The second countershaft sensor 162 is disposed facing the second countershaft magnet 191 across a gap. The first countershaft sensor 161 is disposed facing the first countershaft magnet 181 in the axial direction of the first countershaft 50. The first countershaft sensor 161 detects a change in the magnetic field accompanying the rotation of the first countershaft magnet 181. Similarly, the second countershaft sensor 162 is disposed facing the second countershaft magnet 191 in the axial direction of the second countershaft 70. The second countershaft sensor 162 detects a change in the magnetic field accompanying the rotation of the second countershaft magnet 191.

[0068] At this time, the heights of the sensor substrates 150 and 160 are determined by the processed surfaces 98, 99, and 100 of the support 90, and also the heights of the sensors 151, 161, and 162. The heights of the magnets 181 and 191 are also determined. Therefore, the distance between the magnets and the sensors is constant.

[0069] The shield cover 170 is a magnetic shielding member. The shield cover 170 is made of a soft magnetic material and a conductive material. The shield cover 170 has a rectangular tube portion 171 and a flat plate portion 172 that closes one opening of the rectangular tube portion 171. As shown in FIG. 2, mounting screws Sc10 and Sc11 that pass through the shield cover 170 are screwed into the support 90, whereby the shield cover 170 is fixed to the end of the support 90 facing the motor with the spindle sensor board 150 sandwiched between them. At this time, the shield cover 170 does not come into contact with motor-side components made of a magnetic material.

[0070] The shield cover 170 is spaced apart from the three pairs of sensors 151, 161, 162, the magnets 29, 181, 191, and the magnetic shielding members 30, 182, 192. That is, the shield cover 170 surrounds the components of the rotary encoder 10, such as the main shaft 20, the first counter shaft 50, the second counter shaft 70, the support 90, the gear housing case 110, the main shaft sensor board 150, and the counter shaft sensor board 160. Specifically, the shield cover 170 made of a magnetic shielding member is disposed so as to surround, at a distance, the surface of the main shaft sensor 151 opposite to the surface facing the main shaft magnet 29, the surface (side surface) of the main shaft sensor 151 perpendicular to the surface facing the main shaft magnet 29, and the surfaces (side surfaces) of the counter shaft sensors 161, 162 perpendicular to the surfaces facing the counter shaft magnets 181, 191.

[0071] The shield cover 170, which is a magnetic shielding member, covers the outer surface of the entire sensor. The shield cover 170 and the magnetic shielding members 30, 182, 192 are made of soft magnetic materials, the magnets 29, 181, 191 are made of hard magnetic materials, and the rest are made of non-magnetic materials. The shield cover 170 is configured so that there is no magnetic body in close proximity to the magnets 29, 181, 191 without contacting them. The sensor board 150 and the shield cover 170 made of a conductive member are fixed to the support 90 made of a conductive member. The ground line of the sensor board 150 is in a conductive state with the support 90 and the shield cover 170. In other words, the shield cover 170 is fixed to the support 90 with the spindle sensor board 150 on which the spindle sensor 151 is mounted sandwiched therebetween. The shield cover 170 and the support 90 are connected to the frame ground pattern of the signal ground pattern and the frame ground pattern arranged on the spindle sensor board 150.

[0072] The gear housing box 110, the main shaft gear 40, the first countershaft gear 61, and the second countershaft gear 81 are made of the same resin material, and therefore have the same linear expansion coefficient. Specifically, the gear housing box 110, the main shaft gear 40, the first countershaft gear 61, and the second countershaft gear 81 are made of, for example, polyacetal (POM). Other materials that can be used include, for example, polyamide and polyphenylene sulfide (PPS).

[0073] The material of the first countershaft 50 and the second countershaft 70 is stainless steel. Next, the operation of the rotary encoder 10 will be described. The main shaft 20 is fixed to one end 504 of the motor shaft. The rotation angle of the motor 501 is detected using sensors 151, 161, and 162. The number of teeth of the gears 40, 61, and 81 of the main shaft 20 and the sub-shafts 50 and 70 are different, and they rotate with different phases. Specifically, for example, the number of teeth of the main shaft is the least, such as "21" for the main shaft teeth and "23" and "25" for the sub-shaft teeth. The rotation angles of the main shaft gear 40 and the sub-shaft gears 61 and 81 are measured, and the rotation angle and rotation speed of the main shaft 20 can be calculated as a function of the phase shift and the number of teeth of each gear. Since it is not restricted by the relationship of the number of teeth, the measured rotation speed can be changed by replacing the gear housing body 110. At this time, since the measurable rotation speed can be calculated by the integrated value of the number of teeth of the sub-shaft, it is also possible to set conditions without changing the sensor pitch.

[0074] <Function of the lubrication mechanism for gears and sliding bearings> As shown in FIG. 15, the main shaft gear 40 is located inside the gear housing body 110. The gear housing body 110 houses the main shaft gear 40, the first sub-shaft gear 61, and the second sub-shaft gear 81 in a state of surrounding the periphery of the meshing main shaft gear 40, the first sub-shaft gear 61, and the second sub-shaft gear 81 with a minute gap. The gear housing body 110 is filled with grease Gr1. The gear housing body 110 has grease storage portions 146, 147, 148 and grease circulation paths R1, R2 as shown in FIG. 15. The grease storage portions 146, 147, 148 are formed between the tooth valleys of the main shaft gear 40 and the sub-shaft gears 61, 81 and the gear housing body 110. The grease circulation paths R1, R2 extend such that one end opens at the meshing portion of one adjacent gear and the other end opens at the meshing portion of the other adjacent gear as shown in FIG. 15.

[0075] When the main shaft 20 and the main shaft gear 40 rotate counterclockwise as indicated by arrow A1 in FIG. 16 with the rotation of one end 504 of the motor shaft, with the rotation of this main shaft gear 40, the first sub-shaft gear 61 and the second sub-shaft gear 81 meshing with the main shaft gear 40 rotate clockwise as indicated by arrows B1 and C1.

[0076] At this time, as shown in FIG. 16, the grease Gr1 fills the space between the gear housing box 110 and the tooth valleys of the gears 40, 61, and 81. Then, it moves with the teeth of the gears 40, 61, and 81 as shown by the arrows A10, A11, B10, B11, C10, and C11. When the grease Gr1 reaches the meshing portion of the gears 40, 61, and 81 in FIG. 16, the grease Gr1 is pushed out from the tooth valleys. A new valley space is generated on the opposite side where the rotation has progressed, but it is difficult to supply the grease Gr1. When the gap is narrow as described above, the pressure of the grease Gr1 increases at the meshing portion, and it is easily discharged to the outside.

[0077] In this embodiment, the gear housing box 110 is provided with openings OP1, OP2, OP3, and OP4 from the gaps as shown in Fig. 15. A circulation path R1 is formed in a space connecting the opening OP1 and the opening OP2 of the adjacent meshing portion. A circulation path R2 is formed in a space connecting the opening OP3 and the opening OP4 of the adjacent meshing portion. Grease Gr1 discharged from the meshing portion circulates through the circulation paths R1 and R2 as shown by arrows D1, D2, and D3 and arrows E1, E2, and E3 in Fig. 16, and is replenished into the newly generated valley space.

[0078] In this way, the grease pressure is not increased, so that leakage to the outside is suppressed and the grease can be supplied to the valley portions of the rotating teeth. When the rotation direction of the main shaft gear 40 is reversed, the discharge side of the grease Gr1 and the side where new tooth valleys occur are reversed, and the supply and demand relationship is switched.

[0079] Therefore, a large amount of grease can be used, the lubricating performance is good, and lubrication is maintained for a long period of time. As a result, reliability is improved. In other words, heat generation and wear are prevented by stable lubrication.

[0080] The cross-sectional area of ​​the circulation paths R1, R2 may be the cross-sectional area of ​​the tooth width x the cross-sectional area of ​​the tooth valley, but may be configured to be larger than that so as to have a grease storage function as shown in FIG. The sliding surfaces of the gears 61, 81 and the gear housing box 110 are uneven. That is, as shown in FIG. 3, between the inner surface of the gear housing box 110 at the end face side of the countershaft gears 61, 81 and the magnet holder 62, 82, the convex parts 133, 134 formed on one side are inserted into the concave parts 64, 84 formed on the other side with a certain interval. With this configuration, the contact area and space of the grease are increased compared to when the end face side of the countershaft gears 61, 81 is flat, and the grease Gr1 can be prevented from moving to the outer diameter side due to the centrifugal force when the gears rotate. Therefore, the grease retention of the contact end faces of the countershaft gears 61, 81 is improved. That is, the gear end faces at the magnet holder 62 prevent the grease from flowing out in the radial direction by the unevenness that meshes with the gear housing box 110. The gear end face in magnet holding portion 82 has a projection and recess that mesh with gear housing box 110 to prevent grease from flowing out in the radial direction.

[0081] Since the gears 40, 61, 81 and the gear housing body 110 are made of the same material, dimensional changes in the minute gaps around the gears 40, 61, 81 are suppressed even if the temperature rises due to heat generation by the motor 501.

[0082] The magnet holding portion 62, 82 has a recess 67, 87 into which the magnet holding body 180, 190 that holds the countershaft magnet 181, 191 is inserted. The pin press-fit hole 66, 86 as a shaft fixing hole opens to the bottom surface of the recess 67, 87. A gap Sp1, Sp2 is formed between the bottom surface of the recess 67, 87 and the magnet holding body 180, 190. Grease Gr2, Gr3 is stored in the gap Sp1, Sp2. This lubricates the sliding bearing.

[0083] <Effects of the structure that reduces thermal effects and improves positional accuracy> As shown in FIG. 3, the main shaft 20 has a thermal resistance portion formed by the hollow cylindrical portion 25a extending the motor shaft insertion hole 23. Therefore, the thermal resistance increases due to the reduction in the cross-sectional area, and the amount of heat transferred decreases, resulting in a temperature gradient. As a result, since the heat source is the motor 501, the motor heat is less likely to be transferred to the sensors 151, 161, 162 and the magnets 29, 181, 191. Therefore, the heat transferred from one end 504 of the motor shaft is reduced, the gap accuracy of the sensors 151, 161, 162 is maintained, and the gear housing box 110 and the gears 40, 61, 81 are easily attached. That is, as shown in FIG. 3, heat Q1 toward the main shaft magnet 29 out of the heat generated in the motor 501 passes through the main shaft 20. At this time, the thermal resistance portion formed by the hollow cylindrical portion 25a suppresses the heat transfer from the motor 501 to the main shaft magnet 29 of the main shaft 20. This reduces the heat transferred from the motor 501 side. In order to reduce the positional deviation due to heat, the thermal resistance can be adjusted by adjusting the thickness and length of the hollow cylindrical portion 25a.

[0084] In addition, convex surfaces 96, 97 are formed on the mounting surface of the motor 501 on the support 90, and the tip surfaces of the convex surfaces 96, 97 are in contact with the motor 501 side. As a result, as shown in FIG. 3, heat Q2 generated in the motor 501 and directed toward the rotary encoder 10 passes through the support 90, but the heat transfer from one surface 503a of the bearing holder 503 to the support 90 is suppressed. Specifically, a thermal resistance portion is provided by the convex surfaces 96, 97 at the motor mounting portion on the bottom surface of the support 90. More specifically, the contact portions of the convex surfaces 96, 97 are concentrated around the through holes 94, 95, etc., and reduced to a minimum area. This reduces the amount of heat transfer, thereby reducing the temperature rise and dimensional change due to temperature. The amount of contact area may be adjusted so that the amount of temperature change in the gap between the spindle magnet 29 and the sensor 151 is reduced.

[0085] Furthermore, the spindle magnet holder 25 that holds the spindle magnet 29 is screwed into the spindle 20. As a result, as shown in FIG. 3, heat Q1 generated in the motor 501 and directed toward the spindle magnet 29 passes through the spindle 20, but the heat transfer from the motor 501 to the spindle magnet 29 of the spindle 20 is suppressed. In other words, the magnet holder 25 is made a separate part from the spindle 20 and is fastened with a screw, which acts as a contact resistance and reduces the temperature. This prevents the temperature of the magnets 29, 181, and 191 from rising. This prevents a decrease in magnetic field strength and suppresses positional deviation of the tips of the magnets 29, 181, and 191.

[0086] In addition, since the tip surface of the spindle 20 on the side opposite to the motor and the magnet holder 25 are in surface contact with each other, heat Q1 generated in the motor 501 and directed toward the spindle magnet 29 passes through the spindle 20, but heat transfer from the motor 501 to the spindle magnet 29 of the spindle 20 is suppressed.

[0087] The main shaft sensor board 150 is attached to the machined surface 100 of the support 90 at the tip of the support pillar that protrudes from the square base portion 91. Therefore, the distance between the magnet 29 and the sensor 151 is set with high precision. Also, the counter shaft sensor board 160 is fixed to the machined surface 98 of the support 90, and the gear housing box 110 is fixed to the machined surface 99 of the support 90. This allows the distance between the sensors 161, 162 on the counter shaft side and the magnets 181, 191 to be set with high precision. In this way, the machined surfaces 98, 99, 100 are used as positioning parts to determine the distance between the sensors 151, 161, 162 and the magnets 29, 181, 191 as well as the positioning of the sensor centers.

[0088] Since the gear housing body 110 and the gears 40, 61, 81 are molded from the same resin material, positional deviation due to heat is suppressed. In addition, the support 90 and the outermost shield cover 170 are also thermally connected to each other, which improves the dissipation of heat Q10 generated by the motor 501 as shown in FIG.

[0089] <Function of magnetic shielding structure> As shown in FIG. 3, the main shaft magnet 29 is arranged so that the main shaft sensor 151 arranged on one side of the meshed main shaft gear 40 and counter shaft gears 61, 81 faces in the tooth width direction. The counter shaft magnets 181, 191 are arranged so that the counter shaft sensors 161, 162 arranged on the other side face face face face. The main shaft magnet magnetic shielding member 30 is arranged on the side of the main shaft magnet 29 opposite to the side facing the main shaft sensor 151. The counter shaft magnet magnetic shielding members 182, 192 are arranged on the side of the counter shaft magnets 181, 191 opposite to the side facing the counter shaft sensors 161, 162. This makes it possible to reduce the influence between magnets, especially the main shaft magnet 29. In a broad sense, the main shaft sensor 151 is less susceptible to the influence of the magnetic field of the counter shaft magnets 181, 191, and the counter shaft sensors 161, 162 are less susceptible to the influence of the magnetic field of the main shaft magnet 29. Specifically, by mounting the magnetic shielding members 30, 182, 192, leakage of the magnetic field to the mounting side is suppressed, and the strength of the magnetic field distribution on the opposite side can be adjusted, suppressing mutual magnetic field influence. The thickness of the magnetic shielding members 182, 192 on the countershaft 50, 70 side is thicker than the magnetic shielding member 30 on the main shaft 20 side. Therefore, the magnetic field distribution on the main shaft sensor 151 side in the countershaft magnets 181, 191 is weakened. This reduces the influence on the highly sensitive main shaft sensor 151. More specifically, the main shaft sensor 151 is required to have high detection accuracy, but the detection accuracy of the countershaft sensors 161, 162 may be low. Specifically, the current angle is determined by calculating whether the main shaft 20 is rotating for the first or second rotation, i.e., by determining whether the main shaft 20 is rotating for the first or second rotation, based on the detection result of the main shaft sensor 151. In this case, the magnetic field is more likely to be generated because the main shaft magnet magnetic shielding member 30 is thinner. In other words, by setting the virtual distance between the magnets 29, 181, and 191 long, it is possible to reduce the mutual influence of the magnets and shorten the physical distance, thereby achieving miniaturization.

[0090] Electromagnetic noise is effectively blocked by the shield cover 170. More specifically, the influence of external magnetic fields is suppressed by the shield cover 170. Even if a magnetic field is induced by an external magnetic field, the shield cover 170 makes it difficult for the magnets 29, 181, and 191 to be affected.

[0091] According to the above embodiment, the following effects can be obtained. (1) Since a thermal resistance portion consisting of hollow cylindrical portion 25a is provided between the connecting portion of one end 504 of the motor shaft in main shaft 20 and the fixed portion of main shaft gear 40, heat generated in motor 501 is less likely to be transmitted to main shaft magnet 29. Therefore, the distance between main shaft magnet 29 and main shaft sensor 151 can be kept constant. Also, the characteristics of main shaft magnet 29 can be stabilized.

[0092] (2) The mounting surface of motor 501 on support 90 has convex surfaces 96, 97 formed thereon, and the tip surfaces of convex surfaces 96, 97 are in contact with the motor side, so that heat generated in motor 501 is less likely to be transmitted to support 90. Therefore, the distance between spindle magnet 29 and spindle sensor 151 can be kept constant, and the characteristics of spindle magnet 29 can be stabilized.

[0093] (3) Because the spindle magnet holder 25 that holds the spindle magnet 29 is screwed together with the spindle 20, the following advantages are obtained compared to the case where the spindle magnet holder 25 and the spindle 20 are configured as a single part. By making the spindle magnet holder 25 and the spindle 20 separate and screwing them together, heat generated in the motor 501 is less likely to be transmitted to the spindle magnet holder 25. As a result, the distance between the spindle magnet 29 and the spindle sensor 151 can be kept constant, and the characteristics of the spindle magnet 29 can be stabilized.

[0094] (4) The spindle sensor board 150 is positioned on the machining surface 100, which serves as the positioning surface of the support 90 for the pillars 92 in the axial direction of the spindle 20. Therefore, the distance between the spindle magnet 29 and the spindle sensor 151 can be kept constant, compared to the case where the spindle sensor board 150 is installed on the support 90 via an intermediate object.

[0095] (5) The main shaft sensor board 150, the gear housing box 110, and the counter shaft sensor board 160 are positioned on the machined surfaces 98, 99, and 100, which serve as positioning surfaces of the support 90's pillars 92 in the axial direction of the main shaft 20. Meanwhile, the counter shaft magnets 181, 191 are held by the counter shaft gears 61, 81, so that the positions of the counter shaft magnets 181, 191 are determined by the position of the gear housing box 110. Thus, the distance between the main shaft magnet 29 and the main shaft sensor 151, and the distance between the counter shaft magnets 181, 191 and the counter shaft sensors 161, 162 can be kept constant. In addition, since the support 90 is a single positioning part, errors do not accumulate. Furthermore, errors can be eliminated by machining them simultaneously.

[0096] The embodiment is not limited to the above, and may be embodied as follows, for example. Although there are two countershafts in the embodiment shown in Fig. 15 etc., this is not limiting. For example, as shown in Fig. 17, a structure having a countershaft gear 200 attached to one countershaft may be used. Also, as shown in Fig. 18, a structure having countershaft gears 210, 220, 230 attached to three countershafts may be used.

[0097] 17, the gear housing box 110 has grease reservoirs 146, 201 and grease circulation paths R10, R11. The grease reservoirs 146, 201 are formed between the tooth valleys of the main shaft gear 40 and the countershaft gear 200 and the gear housing box 110. The grease circulation paths R10, R11 extend so that one end opens into the meshing portion of one adjacent gear and the other end opens into the meshing portion of the other adjacent gear.

[0098] 18, the gear housing box 110 has grease reservoirs 146, 211, 221, 231 and grease circulation paths R20, R21, R22. The grease reservoirs 146, 211, 221, 231 are formed between the tooth valleys of the main shaft gear 40 and the countershaft gears 210, 220, 230 and the gear housing box 110. The grease circulation paths R20, R21, R22 extend so that one end opens into the meshing portion of one adjacent gear and the other end opens into the meshing portion of the other adjacent gear.

[0099] In the above embodiment shown in Fig. 3 etc., the countershaft is a stainless steel round bar, but this is not limited thereto. For example, as shown in Fig. 19, the countershaft 240 may be made of porous ceramic. Alternatively, as shown in Fig. 20, the countershaft 250 may be a hollow metal pipe, for example a stainless steel pipe.

[0100] If the countershaft is a stainless steel pipe, the amount of grease can be increased. Also, in the case where a hollow metal pipe is used as the countershaft 250 in Fig. 20, a horizontal hole 251 can be provided. The countershaft may be made of ceramic.

[0101] In this way, the material of the countershaft can be stainless steel, ceramic, etc. If a stainless steel pipe or porous ceramic is used, the grease retention effect is higher. [Explanation of symbols]

[0102] 10...rotary encoder, 20...main shaft, 25...magnet holder, 25a...cylindrical portion, 29...main shaft magnet, 40...main shaft gear, 50...first counter shaft, 61...first counter shaft gear, 70...second counter shaft, 81...second counter shaft gear, 90...support, 92...pillar, 96...convex surface, 97...convex surface, 98...machined surface for positioning counter shaft sensor board (positioning surface), 99...machined surface for positioning box (positioning surface), 100...machined surface for positioning main shaft sensor board (positioning surface), 110...gear accommodating box, 150...main shaft sensor board, 151...main shaft sensor, 160...counter shaft sensor board, 161...first counter shaft sensor, 162...second counter shaft sensor, 181...first counter shaft magnet, 191...second counter shaft magnet.

Claims

1. A main shaft connected to the motor shaft; A main shaft gear fixed to the main shaft; A main shaft magnet held by the main shaft; a spindle sensor disposed opposite the spindle magnet in the axial direction of the spindle and configured to detect a change in a magnetic field caused by rotation of the spindle magnet; a spindle sensor board on which the spindle sensor is mounted; A support for supporting the spindle sensor substrate; A rotary encoder comprising: a heat resistance portion formed of a hollow cylindrical portion is provided between a connecting portion of the motor shaft on the main shaft and a fixing portion of the main shaft gear; the support body is configured as an integral body including a base portion through which the spindle passes and a support column extending from the base portion in the axial direction of the spindle, The support has a positioning surface for positioning the spindle sensor board in the axial direction of the spindle. A rotary encoder comprising:

2. A convex surface is formed on the motor mounting surface of the support, and the tip surface of the convex surface is in contact with the motor side.

2. The rotary encoder according to claim 1 .

3. A main shaft magnet holder that holds the main shaft magnet is screwed into the main shaft.

3. The rotary encoder according to claim 1, wherein the rotary encoder comprises:

4. a countershaft gear that meshes with the mainshaft gear; A countershaft that rotatably supports the countershaft gear; a countershaft magnet held by the countershaft gear; a counter shaft sensor disposed opposite the counter shaft magnet in the axial direction of the counter shaft and configured to detect a change in a magnetic field caused by rotation of the counter shaft magnet; a secondary shaft sensor board on which the secondary shaft sensor is mounted; Further comprising: The support supports the main shaft sensor substrate and the secondary shaft sensor substrate.

4. The rotary encoder according to claim 1, wherein the rotary encoder is a rotary encoder having a first end and a second end.

5. The gear receiving box further includes a gear receiving box for receiving the meshed main shaft gear and the counter shaft gear, The support body has a support pillar extending in the axial direction of the main shaft, The support pillar has a positioning surface for the main shaft sensor board, a positioning surface for the gear accommodating box, and a positioning surface for the counter shaft sensor board, which are located at different positions in the axial direction of the main shaft.

5. The rotary encoder according to claim 4.

6. A main shaft connected to the motor shaft; A main shaft gear fixed to the main shaft; A main shaft magnet held by the main shaft; a spindle sensor disposed opposite the spindle magnet in the axial direction of the spindle and configured to detect a change in a magnetic field caused by rotation of the spindle magnet; a spindle sensor board on which the spindle sensor is mounted; A support for supporting the spindle sensor substrate; A rotary encoder comprising: a heat resistance portion formed of a hollow cylindrical portion is provided between a connecting portion of the motor shaft on the main shaft and a fixing portion of the main shaft gear; a countershaft gear that meshes with the mainshaft gear; A countershaft that rotatably supports the countershaft gear; a countershaft magnet held by the countershaft gear; a counter shaft sensor disposed opposite the counter shaft magnet in the axial direction of the counter shaft and configured to detect a change in a magnetic field caused by rotation of the counter shaft magnet; a secondary shaft sensor board on which the secondary shaft sensor is mounted; a gear housing box that houses the meshing main shaft gear and the counter shaft gear; Further comprising: the support body has a support pillar extending in an axial direction of the main shaft and supports the main shaft sensor board and the counter shaft sensor board; The support pillar has a positioning surface for the main shaft sensor board, a positioning surface for the gear accommodating box, and a positioning surface for the counter shaft sensor board, which are located at different positions in the axial direction of the main shaft. A rotary encoder comprising:

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