JP6029273B2 - Gear transmission - Google Patents

Description

  The present invention relates to a gear transmission provided with an axial gap motor.

  A gear transmission in which an external gear rotates eccentrically while meshing with an internal gear is known. Such a gear transmission is sometimes called a cycloid reducer, and an example thereof is disclosed in Patent Document 1. In the gear transmission of Patent Document 1, the external gear engages with an eccentric body fixed to the crankshaft and rotates eccentrically. A rotor of a radial gap motor is attached to the crankshaft.

International Publication WO2009 / 081793 Pamphlet

  In order to realize a thin gear transmission, it is preferable to use a thin motor. Therefore, in order to realize a thin gear transmission, it is preferable to use an axial gap motor.

  On the other hand, in the axial gap motor in which the rotor and the stator are opposed in the axial direction, the width of the gap between the rotor and the stator is likely to change. If the width of the gap changes during rotation, the generated torque will change. The present specification provides a gear transmission having a new structure that maintains a constant gap width between a rotor and a stator by utilizing a structure peculiar to an eccentric oscillating gear transmission.

  A gear transmission disclosed in this specification includes a case, a carrier, a crankshaft, an external gear, and an axial gap motor. An internal gear is formed on the inner periphery of the case. The carrier is supported by the case coaxially with the internal gear. The crankshaft is supported on the carrier by a pair of bearings. The crankshaft has an eccentric body. The external gear engages with the eccentric body and rotates eccentrically while meshing with the internal gear. The motor of the axial gap motor is attached to the crankshaft. In this gear transmission, the rotor of the axial gap is located between a pair of bearings that support the crankshaft.

  Between the pair of bearings, the vibration of the rotating crankshaft is strictly suppressed. However, the crankshaft is cantilevered outside the pair of bearings, and shaft runout may occur with rotation. If the rotor of the axial gap motor is fixed to the crankshaft between the pair of bearings, the rotor can be maintained at a fixed position, and the gap width between the rotor and the stator can be maintained constant. As a result, the output torque of the axial gap motor can be kept constant.

  In the gear transmission disclosed in the present specification, two axial gap motors may be mounted facing the crankshaft. In this case, the rotors of both axial gap motors are preferably located between the pair of bearings. The attractive force generated in the two axial gap motors is balanced, and the gap between the rotor and the stator can be made more difficult to change.

  The crankshaft may be disposed coaxially with the carrier, or may be disposed at a position offset from the carrier axis. If the crankshaft is arranged coaxially with the carrier, torque can be transmitted to the central portion of the external gear. Torque can be uniformly transmitted to the external gear.

  When the crankshaft is disposed coaxially with the carrier, a through hole concentric with the carrier axis is formed in the crankshaft, and the rotor of the axial gap motor may be fixed in the through hole. A gear transmission equipped with a compact motor can be realized by effectively using the through hole.

  When the crankshaft is arranged coaxially with the carrier, it is engaged with the external gear at a position offset from the carrier axis, and has a plurality of driven crankshafts that rotate as the external gear rotates eccentrically. It may be. In this case, the respective driven crankshafts are preferably arranged at equal intervals around the carrier axis. By providing the driven crank, rattling of the external gear is suppressed, and the external gear can be smoothly rotated.

  In the gear transmission disclosed in this specification, the crankshaft may include a plurality of eccentric bodies. In this case, it is preferable that the eccentric bodies are fixed to the crankshaft so that the eccentric directions of the eccentric bodies are different, and the centers of the eccentric bodies are positioned at equal intervals on a concentric circle with the axis of the crankshaft. In such a gear transmission, the eccentric directions of the plurality of external gears are different. The position where each external gear meshes with the internal gear is dispersed in a balanced manner in the circumferential direction of the gear transmission. A gear transmission with good driving balance can be realized.

  In the gear transmission disclosed in the present specification, the eccentric body may be positioned between a pair of bearings supporting the crankshaft. Since shakiness of the eccentric body is suppressed, the external gear engaged with the eccentric body can be rotated more smoothly.

  The technology disclosed in the present specification can realize a gear transmission in which the axial gap motor that drives the crankshaft outputs a stable torque in a gear transmission that includes an axial gap motor.

Sectional drawing of the gear transmission of 1st Example is shown. The expanded sectional view of the part II enclosed with the broken line of FIG. 1 is shown. The top view of the state which removed the cover from the carrier about the gear transmission of 1st Example is shown. Sectional drawing of the gear transmission of 2nd Example is shown.

(First embodiment)
A gear transmission 100 shown in FIG. 1 is an eccentric oscillating type speed reducer in which an external gear 24 rotates eccentrically while meshing with an internal gear 32. In the gear transmission 100, the carrier 8 rotates according to the difference between the number of teeth of the external gear 24 and the number of teeth of the internal gear 32. The internal gear 32 includes a case 6 and a plurality of internal gear pins 34 disposed on the inner periphery of the case 6. Note that this type of gear transmission is sometimes called a cycloid reducer.

  The gear transmission 100 includes a case 6, a carrier 8, a crankshaft 12, an external gear 24, and axial gap motors 18 and 48. The carrier 8 includes a first plate 8a and a second plate 8c. A columnar portion 8b extends from the first plate 8a toward the second plate 8c. The columnar portion 8b and the second plate 8c are fixed. The columnar portion 8 b passes through the through hole 52 of the external gear 24. The carrier 8 is supported on the case 6 coaxially with the internal gear 32 by a pair of angular ball bearings 4. In other words, the movement of the carrier 8 in the axial direction and the radial direction is restricted by the angular ball bearing 4. The axis 40 corresponds to the axis of the carrier 8. The axis 40 corresponds to the axis of the internal gear 32 (case 6). The groove formed in the carrier 8 corresponds to the inner race of the angular ball bearing 4.

  The crankshaft 12 is disposed coaxially with the carrier 8. That is, the axis of the crankshaft 12 is equal to the axis 40 of the carrier 8. The crankshaft 12 is supported on the carrier 8 by a pair of deep groove ball bearings 50. That is, the movement of the crankshaft 12 in the axial direction and the radial direction is regulated by the pair of deep groove ball bearings 50. The crankshaft 12 includes two eccentric bodies 22. The eccentric body 22 is located between the pair of deep groove ball bearings 50 in the direction of the axis 40. Each eccentric body 22 is symmetrically eccentric with respect to the axis 40. Each eccentric body 22 is engaged with an individual external gear 24 via a cylindrical roller bearing 23. The crankshaft 12 has a through hole 12a, and axial gap motors 18 and 48 are attached in the through hole 12a (see FIG. 2). An encoder 20 is attached to the crankshaft 12. Details of the encoder 20 and the axial gap motors 18 and 48 will be described later.

  The driven crankshaft 26 is disposed at a position offset from the axis 40. The driven crankshaft 26 extends parallel to the crankshaft 12. In other words, the axis 36 of the driven crankshaft 26 is parallel to the axis 40 of the crankshaft 12. The driven crankshaft 26 is supported on the carrier 8 by a pair of tapered roller bearings 38. The driven crankshaft 26 includes two driven eccentric bodies 35. The driven eccentric body 35 is located between the pair of tapered roller bearings 38 in the direction of the axis 36. In addition, each driven eccentric body 35 is eccentrically symmetrical with respect to the axis 36. Each driven eccentric body 35 is engaged with an individual external gear 24. A brake 28 is attached to the end of the driven crankshaft 26. A motor is not attached to the driven crankshaft 26.

  When the crankshaft 12 rotates, the eccentric body 22 rotates eccentrically around the axis 40. As the eccentric body 22 rotates eccentrically, the external gear 24 rotates eccentrically around the axis 40 while meshing with the internal gear 32. The number of teeth of the external gear 24 and the number of teeth of the internal gear 32 (number of internal pins 34) are different. Therefore, when the external gear 24 rotates eccentrically, the carrier 8 rotates relative to the internal gear 32 (case 6) according to the difference in the number of teeth between the external gear 24 and the internal gear 32. The driven crankshaft 26 does not transmit the motor torque directly, and rotates as the external gear 24 rotates eccentrically. The driven crankshaft 26 suppresses rattling of the external gear 24 and assists in smoothly rotating the external gear 24 eccentrically.

  The axial gap motors 18 and 48 will be described in detail with reference to FIGS. 1 and 2. In the following description, the first axial gap motor 18 and the second axial gap motor 48 may be referred to. The first axial gap motor 18 includes a first rotor 16 and a first stator 14. A gap 60 exists between the first rotor 16 and the first stator 14. The first rotor 16 includes a rotor plate 17 and a first permanent magnet 15. The first permanent magnet 15 is fixed to one surface of the rotor plate 17. The rotor plate 17 is press-fitted into the inner wall of the through hole 12a of the crankshaft 12. Therefore, the first rotor 16 can also be expressed as being attached to the crankshaft 12 in the through hole 12a of the crankshaft 12. The through hole 12 a is formed concentrically with the axis 40 of the carrier 8. In addition, the rotor plate 17 includes an extension portion 17 a extending along the axis 40 from one surface.

  The first stator 14 includes a first stator core 13 and a first winding 11. The first stator 14 is disposed in the through hole 12a. Therefore, it can be expressed that the first axial gap motor 18 is disposed in the through hole 12 a of the crankshaft 12. The first winding 11 is wound around a first stator core 13 formed of a dust core. The first stator core 13 is fixed to the first stator plate 21. The first stator plate 21 is fixed to the carrier 8 (first plate 8a). Therefore, it can be expressed that the first stator 14 is fixed to the carrier 8. A through hole 13 a is formed in the first stator core 13. The extension 17a of the rotor plate 17 passes through the through hole 13a. The encoder 20 is fixed to the end portion of the extension portion 17a. That is, the encoder 20 is fixed to the extension portion 17 a of the rotor plate 17 outside the first stator plate 21. The rotation angle of the crankshaft 12 can be detected by the encoder 20.

  In addition, although illustration is abbreviate | omitted, the 1st permanent magnet 15 has the permanent magnet in which the N pole faces outside, and the permanent magnet in which the S pole faces outside. On the rotor plate 17, permanent magnets with N poles facing outward and permanent magnets with S poles facing outward are alternately fixed in the circumferential direction. In the first stator 14, a winding through which a U-phase current flows, a winding through which a V-phase current flows, and a winding through which a W-phase current flows are arranged in order in the circumferential direction.

  The structure of the second axial gap motor 48 is substantially the same as the structure of the first axial gap motor 18. The second axial gap motor 48 will not be described in duplicate with the first axial gap motor 18 and will be briefly described below.

  The second axial gap motor 48 includes a second rotor 46 and a second stator 44. A gap 62 exists between the second rotor 46 and the second stator 44. The second rotor 46 includes the rotor plate 17 and the second permanent magnet 45. The second rotor 46 is integrated with the first rotor 16. That is, the first rotor 16 and the second rotor 46 use a common rotor plate 17. More specifically, the first permanent magnet 15 is fixed to one surface of the rotor plate 17, and the second permanent magnet 45 is fixed to the other surface of the rotor plate 17. The second stator 44 includes a second stator core 43 and a second winding 41. The second stator core 43 is fixed to the second stator plate 39. The second stator plate 39 is fixed to the carrier 8 (second plate 8c). The second stator 44 can also be expressed as being fixed to the carrier 8. The second axial gap motor 48 can also be expressed as being disposed in the through hole 12a of the crankshaft 12. The first axial gap motor 18 and the second axial gap motor 48 have the same phase.

  The characteristics of the gear transmission 100 will be described. As described above, the crankshaft 12 is supported on the carrier 8 by the pair of deep groove ball bearings 50. In the range 72 sandwiched between the pair of deep groove ball bearings 50, the crankshaft 12 is supported at both ends. In other words, within the range 72, the crankshaft 12 is severely restricted from moving (vibrating) in the axial and radial directions during rotation. On the other hand, outside the range 72, the crankshaft 12 can be said to be cantilevered. Therefore, the crankshaft 12 tends to vibrate outside the range 72. In the gear transmission 100, the rotors 16 and 46 are attached to the crankshaft 12 within a range 72. Since the positions of the rotors 16 and 46 do not change, the gap 60 between the first rotor 16 and the first stator 14 and the gap 62 between the second rotor 46 and the second stator 44 are maintained constant. As a result, since the axial gap motors 18 and 48 can output a constant torque, the output torque of the gear transmission 100 can be maintained constant.

  Other features of the gear transmission 100 will be described. The first axial gap motor 18 and the second axial gap motor 48 are attached to the crankshaft 12 so as to face each other. More specifically, the first rotor 16 and the second rotor 46 are disposed between the first stator 14 and the second stator 44. In the case of an axial gap motor, an attractive force acts between the rotor and the stator. By attaching the two axial gap motors 18 and 48 to the crankshaft 12 so as to face each other, the suction forces of the two axial gap motors 18 and 48 act on the crankshaft 12 in opposite directions. In the direction of the axis 40, the force applied to the crankshaft 12 is balanced.

  As described above, the axial gap motors 18 and 48 are disposed in the through hole 12 a of the crankshaft 12. In the case of an axial gap motor, the inertial force increases with the diameter. When the inertial force of the axial gap motor increases, for example, when the drive of the gear transmission is stopped, the stop operation is delayed. By disposing the axial gap motors 18 and 48 in the through hole 12a of the crankshaft 12, the gear transmission 100 can be driven by a motor having a small inertial force. In addition, by arranging two axial gap motors in the through hole 12a, the overall size of the gear transmission with motor can be reduced.

  As described above, the two eccentric bodies 22 are symmetrically eccentric with respect to the axis 40. The direction of eccentricity of the external gear 24 is symmetric, and the balance can be maintained well when the gear transmission 100 is driven. The relationship between the eccentric body 22 and the crankshaft 12 can also be expressed as follows. The crankshaft 12 includes two eccentric bodies 22. The eccentric directions of the eccentric bodies 22 are different. The eccentric bodies 22 are fixed to the crankshaft 12 so that the centers of the respective eccentric bodies 22 are located 180 degrees apart about the axis 40 of the crankshaft.

  Two oil seals 70 are arranged between the crankshaft 12 and the carrier 8 (see FIG. 2). The oil seals 70 are respectively arranged outside the pair of deep groove ball bearings 50. In other words, the pair of deep groove ball bearings 50 is disposed between the two oil seals 70. The oil seal 70 lubricates from the outside of the crankshaft 12 (the space where the external gear 24, the internal gear 32, etc. are present) to the inside of the crankshaft 12 (the space where the axial gap motors 18, 48 and the encoder 20 are present). It is possible to prevent the agent from entering.

  An oil seal 25 is disposed between the driven crankshaft 26 and the carrier 8 (see FIG. 1). The oil seal 25 is located between the tapered roller bearing 38 and the brake 28 in the direction of the axis 36. The oil seal 25 can prevent the lubricant from entering the space where the external gear 24 and the like are present into the space where the brake 28 is present. The cover 30 is fixed to the carrier 8 so as to cover the encoder 20 and the brake.

  Two oil seals 2 are arranged between the case 6 and the carrier 8. The oil seals 2 are respectively arranged outside the pair of angular ball bearings 4. In other words, a pair of angular ball bearings 4 is disposed between the two oil seals 2. Further, a cap 37 is fitted in a hole formed in the second plate 8c. The lubricant sealed in the gear transmission 100 (the space where the external gear 24, the internal gear 32, etc. exist) by the oil seals 70 and 25 and the oil seal 2 and the cap 37 described above is transmitted to the gear transmission. Leaking outside the apparatus 100 is prevented.

  The advantages of having the driven crankshaft 26 will be described with reference to FIGS. FIG. 3 shows a plan view of the gear transmission 100 with the cover 30 removed from the carrier 8. A cross section taken along the line I-I in FIG. As shown in FIG. 3, the gear transmission 100 includes three driven crankshafts 26. The three driven crankshafts 26 are arranged at equal intervals around the axis 40. A brake 28 is attached to each of the three driven crankshafts 26. As described above, the driven crankshaft 26 does not transmit the motor torque to the external gear 24. The driven crankshaft 26 prevents the external gear 24 from rattling. In other words, the driven crankshaft 26 maintains the posture of the external gear 24. The eccentric rotation of the external gear 24 becomes smooth, and backlash or the like can hardly occur. Further, by attaching the brake 28 to the driven crankshaft 26, it is not necessary to attach both the encoder 20 and the brake to the crankshaft 12. As a result, the axial thickness of the gear transmission 100 can be reduced.

(Second embodiment)
The gear transmission 200 will be described with reference to FIG. The gear transmission 200 is a modification of the gear transmission 100, and the same components as the gear transmission 100 may be denoted by the same reference numerals or the same two lower digits, and the description thereof may be omitted.

  The gear transmission 200 includes a central through hole 80 concentric with the axis 40. The gear transmission 200 uses two hollow axial gap motors 218 and 248. More specifically, a through hole 221 a is formed in the first stator plate 221 of the first hollow axial gap motor 218, a through hole 214 a is formed in the first stator 214, and a through hole 216 a is formed in the first rotor 216. Is formed. The second rotor 244 of the second hollow axial gap motor 248 has a through hole 244a, the second stator 246 has a through hole 246a, and the second stator plate 239 has a through hole 239a. ing. In the gear transmission, a through hole 230 a is further formed in the cover 230.

  A hollow shaft 82 is fixed to the through holes 230a and 239a. The hollow shaft 82 passes through the through holes 221a, 214a, 216a, 244a and 246a. By using the central through hole 80, the cable, the shaft, and the like can be passed through the gear transmission 200 in the direction of the axis 40.

  As with the gear transmission 100, the gear transmission 200 includes three driven crankshafts 226. In FIG. 4, only one crankshaft 226 appears, and the other two crankshafts 226 are hidden. In the gear transmission 200, an encoder 220 is attached to one driven crankshaft 226. Brakes (not shown) are attached to the other two driven crankshafts 226.

  Points to be noted in the examples are described. In the above-described embodiment, the form in which the crankshaft is supported using the pair of deep groove ball bearings has been described. Instead of the deep groove ball bearing, an angular ball bearing, an angular roller bearing, a tapered roller bearing or the like may be used. The bearing that supports the crankshaft may be of a type that bears loads in the axial direction and the radial direction.

  In the above-described embodiment, the form in which the crankshaft includes two eccentric bodies has been described. The number of eccentric bodies may be one or three or more. In other words, the number of external gears may be one, or three or more. When the crankshaft is provided with a plurality of eccentric bodies, the eccentric bodies have different directions, and the eccentric bodies are cranked so that the centers of the eccentric bodies are located at equal intervals around the axis of the crankshaft. It is preferably fixed to the shaft. In addition, the balance of a gear transmission can be improved, so that the number of eccentric bodies (the number of external gears) increases.

  In the above-described embodiment, an embodiment in which three driven crankshafts are provided has been described. The number of driven crankshafts may be two, or four or more. The gear transmission may not include a driven crankshaft. As the diameter of the gear transmission, that is, the diameter of the external gear increases, the external gear is more likely to rattle, and the usefulness of the driven crankshaft increases.

  Specific examples of the present invention have been described in detail above, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above. The technical elements described in this specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology exemplified in this specification or the drawings achieves a plurality of objects at the same time, and has technical utility by achieving one of the objects.

6: Case 8: Carrier 12: Crankshaft 16: First rotor 18: First axial gap motor 22: Eccentric body 24: External gear 32: Internal gear
46: second rotor 48: second axial gap motor 50: deep groove ball bearing (a pair of bearings)
100: Gear transmission

Claims (5)

A case in which an internal gear is formed on the inner periphery;
A carrier supported by the case coaxially with the internal gear;
A crankshaft supported by a carrier by a pair of bearings, having an eccentric body and having a through hole ;
An external gear engaged with the eccentric body and rotating eccentrically while meshing with the internal gear;
A rotor is attached to the crankshaft and a stator is attached to the carrier, and two axial gap motors arranged facing each other, and
The rotor is fixed to the rotor plate on a rotor plate fixed to the inner peripheral surface of the through hole, a first permanent magnet fixed to the surface of the rotor plate, and a surface opposite to the first permanent magnet. A second permanent magnet,
The rotor is located between the pair of bearings;
Each of the stators is fixed to a stator plate;
The stator plate is fixed to the carrier without protruding from the axial end surface of the carrier,
When the stator plate is fixed to the carrier, each stator is fixed to the carrier in a state of facing each of the first permanent magnet and the second permanent magnet with a gap. Gear transmission. The gear transmission according to claim 1, wherein the crankshaft is disposed coaxially with the carrier. It is engaged with the external gear at a position offset from the carrier axis, and has a plurality of driven crankshafts that rotate with the eccentric rotation of the external gear,
3. The gear transmission according to claim 2 , wherein the driven crankshafts are arranged at equal intervals around the carrier axis. The crankshaft has a plurality of eccentric bodies,
The eccentric direction of each eccentric body is different,
As the center of each of the eccentric body is positioned at equal intervals on the axis and concentric crankshaft, the eccentric body according to any one of claims 1 to 3, characterized in that it is fixed to the crankshaft Gear transmission. The gear transmission according to any one of claims 1 to 4 , wherein an eccentric body is located between the pair of bearings.

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