Rotary apparatus

Abstract

To provide a rotary apparatus that can further improve heat radiation properties.SOLUTION: A rotary apparatus 1 comprises: gears 50, 51; a motor 4; a housing 2 that accommodates the gears 50, 51 and the motor 4; and a member 17 that has thermal conductivity. The housing 2 includes a wall 21b that crosses between the gears 50, 51 and the motor 4 arranged side by side in an axial direction. The member 17 having thermal conductivity is in contact with the wall 21b and the motor 4 in the axial direction.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a rotating device.

Background Art

[0002] Patent Document 1 discloses a geared motor having a motor and a speed reducer. In this geared motor, the heat generated by the motor is radiated to the outside from a partition wall that separates the motor and the speed reducer.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a geared motor, it is required to further improve heat dissipation.

[0005] Therefore, one of the problems of the present invention is to provide a rotating device capable of further improving heat dissipation.

Means for Solving the Problems

[0006] A rotating device according to an aspect of the present invention includes a gear, a motor, a housing that houses the gear and the motor, and a member having thermal conductivity. The housing includes a wall that crosses between the gear and the motor arranged in the axial direction, and in the axial direction, the member having thermal conductivity is in contact with the wall and the motor.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Figure 3

Figure 4

DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a perspective view schematically showing the structure of a rotating device 1 according to an embodiment of the present invention. FIG. 2 is a cross-sectional view taken along the 2-2 line of FIG. 1. FIG. 2 is a cross-section along a virtual plane including the rotation axis x. This rotating device 1 is a rotating device having a motor and a speed reducer for reducing the rotation of the motor, and is incorporated in, for example, an electric assist bicycle. The rotating device 1 includes a housing 2. The housing 2 generally has a substantially cylindrical shape as a whole, for example. The housing 2 is fixed to the frame of a bicycle, for example. Note that the bicycle includes all types of bicycles such as road bicycles, cross bicycles, mountain bicycles, and city bicycles.

[0009] A crankshaft 3 is rotatably supported in the housing 2 about the rotation axis x. In this example, the rotation axis x coincides with the central axis of the housing 2. The crankshaft 3 has one end 3a on one side S1 in the direction along the rotation axis x (hereinafter referred to as the "rotation axis direction"), and the other end 3b on the other side S2 opposite to the one side S1. Both the one end 3a and the other end 3b protrude from the housing 2 in the rotation axis direction. Crank arms (not shown) extending in a direction orthogonal to the rotation axis x are attached to the one end 3a and the other end 3b, respectively. A pedal (not shown) is attached to the tip of the crank arm. A chain ring (not shown) is further attached to the crank arm attached to the one end 3a.

[0010] The housing 2 has a housing (hereinafter referred to as "motor housing") 20 that houses the motor 4, a housing (hereinafter referred to as "gear housing") 21 that houses the speed reducer 5, and a cover (hereinafter referred to as "gear cover") 22. The motor housing 20, the gear housing 21, and the gear cover 22 are coupled to each other by fastening components 23 such as bolts extending in the rotational axis direction. An annular member (hereinafter referred to as "gasket") 24 seals between the motor housing 20 and the gear housing 21. An annular member (hereinafter referred to as "gasket") 25 seals between the gear housing 21 and the gear cover 22. The housing 2 is formed of, for example, a metal material or a resin material. From the viewpoint of thermal conductivity, the motor housing 20 and the gear housing 21 are preferably formed of a metal material. The gaskets 24 and 25 are formed of a metal material or a resin material having elasticity or resilience.

[0011] The motor housing 20 has a cylindrical outer portion (hereinafter referred to as "outer peripheral portion") 20a centered on the rotational axis x, a cylindrical inner portion (hereinafter referred to as "inner peripheral portion") 20b centered on the rotational axis x, and a wall 20c connecting the outer peripheral portion 20a and the inner peripheral portion 20b. In this example, the wall 20c connects the ends on the other side S2 of the outer peripheral portion 20a and the inner peripheral portion 20b. The outer peripheral portion 20a surrounds the motor 4 from the outer peripheral side in the radial direction orthogonal to the rotational axis x. The inner peripheral portion 20b is disposed inside the motor 4. The inner peripheral surface of the inner peripheral portion 20b faces the outer peripheral surface of the crankshaft 3. The wall 20c extends along a virtual plane orthogonal to the rotational axis x in this example. That is, the wall 20c faces the motor 4 in the rotational axis direction and forms a bottom.

[0012] A bearing 10 is disposed between the inner peripheral side end of the wall 20c and the outer peripheral surface of the crankshaft 3. The bearing 10 is a bearing having rolling elements, for example, a ball bearing. In this way, the motor housing 20 supports the crankshaft 3 so as to be relatively rotatable via the bearing 10 at the inner peripheral side end of the wall 20c. The housing 2 further has an annular end cover 26. The end cover 26 covers the other side S2 of the bearing 10 along the rotational axis direction. The end cover 26 is fixed to the wall 20c by fastening parts 27 such as screws, for example. The other end 3b of the crankshaft 3 projects from the housing 2 to the other side S2 through the hole (through hole) of the end cover 26 formed along the rotational axis x.

[0013] Figure 3 is a cross-sectional view taken along line 3-3 of Figure 2. Referring to Figures 2 and 3 together, the motor 4 has a stator 40 and a rotor 41 that is relatively rotatable with respect to the stator 40. The stator 40 has a magnetic body (hereinafter referred to as "yoke"), that is, a stator core 42, a coil 43, and an insulator 44. The stator core 42 is formed from a laminate in which a plurality of annular silicon steel plates or electromagnetic steel plates are laminated in the rotational axis direction. The stator core 42 is fixed to the inner peripheral surface of the outer peripheral portion 20a of the motor housing 20. The stator core 42 has a plurality of teeth 42a arranged circumferentially around the rotational axis x. The coil 43 is wound around each tooth 42a. The insulator 44 insulates the stator core 42 and the coil 43.

[0014] The stator 40 is covered with a predetermined member 45 (see FIG. 2). The predetermined member 45 is formed of, for example, a resin material having thermal conductivity. A substrate (hereinafter referred to as a "printed circuit board") 46 is fixed to the other side S2 of the predetermined member 45. The printed circuit board 46 is provided with a plurality of electronic components such as wiring for electrically connecting a coil, a temperature sensor for detecting temperature, and a magnetic sensor. The printed circuit board 46 is electrically connected to, for example, the outer peripheral surface of the rotating device 1 or another substrate provided outside. Alternatively, the printed circuit board 46 may be composed of a printed circuit board and a plurality of bus bars, and the printed circuit board and the plurality of bus bars may be electrically connected. A sensor (not shown) for detecting the torque acting on the crankshaft 3 is incorporated in the rotating device 1. A control circuit capable of determining the current value of the current supplied to the coil 43 based on the detected value of the torque from this sensor is mounted on the printed circuit board 46. The coil 43 is supplied with current from, for example, a battery (not shown) mounted on a bicycle. In this way, the control circuit can control the rotational speed of the motor 4 according to the value of the torque of the crankshaft 3.

[0015] The rotor 41 has a magnet 47 and a magnetic body (hereinafter referred to as a "yoke") 48. The yoke 48 is formed of, for example, a magnetic material. A plurality of magnets 47 arranged in the circumferential direction are supported by the yoke 48. The magnet 47 faces the outer peripheral surface of the magnetic pole portion (hereinafter referred to as "teeth") 42a of the stator core 42 with a predetermined magnetic gap. When current is supplied to the coil 43, the rotor 41 can rotate relative to the stator 40 about the rotation axis x due to the magnetic interaction between the coil 43 and the magnet 47. Note that the yoke 48 may be, for example, a cylindrical member centered on the rotation axis x. The magnet 47 may be a single cylindrical permanent magnet, or a plurality of permanent magnets may be connected to each other in the circumferential direction to form a cylindrical shape.

[0016] The rotor 41 is attached to the motor shaft 49. For example, the rotor 41 is fixed to the outer peripheral surface of the motor shaft 49, for example, by press-fitting. The motor shaft 49 is formed in a cylindrical shape centered on, for example, the rotation axis x. The motor shaft 49 extends from inside the motor housing 20 to inside the gear housing 21. The motor shaft 49 is supported so as to be relatively rotatable via a bearing 11 on the outer peripheral surface of the inner peripheral portion 20b of the motor housing 20 adjacent to the end portion on the other side S2. The bearing 11 is a bearing having rolling elements, for example, a ball bearing. In the rotation axis direction, the inner peripheral surface of the motor shaft 49 faces the outer peripheral surface of the crankshaft 3 on one side S1 from the inner peripheral portion 21b. In the gear housing 21, a speed reducer 5 described later is connected to the end portion on one side S1 of the motor shaft 49.

[0017] The gear housing 21 has a cylindrical outer portion (hereinafter referred to as the "outer peripheral portion") 21a centered on the rotation axis x and a wall 21b extending inward from the outer peripheral portion 21a toward the rotation axis x. In this example, the wall 21b extends inward from the end portion on the other side S2 of the outer peripheral portion 21a. The gear cover 22 has a cylindrical outer portion (hereinafter referred to as the "outer peripheral portion") 22a centered on the rotation axis x and a cylindrical inner portion (hereinafter referred to as the "inner peripheral portion") 22b having a smaller diameter and located inside the outer peripheral portion 22a and centered on the rotation axis x. The speed reducer 5 is housed in the gear housing 21 and the gear cover 22. The speed reducer 5 is arranged side by side with the motor 4 in the rotation axis direction. The wall 21b is formed in an annular shape extending across between the motor 4 and the speed reducer 5. That is, the speed reducer 5 is arranged on the opposite side of the motor 4 with the wall 21b interposed therebetween in the rotation axis direction.

[0018] The speed reducer 5 is configured as a cycloid speed reducer as an example. The speed reducer 5 has a first gear 50 supported on the outer peripheral surface of the motor shaft 49 via a bearing 12, and a second gear 51 disposed on the outer peripheral side of the first gear 50. The bearing 12 is a bearing having rolling elements, for example, a ball bearing. The second gear 51 is fixed to the inner peripheral surface of the outer peripheral portion 21a. A plurality of teeth (not shown) are formed in the circumferential direction on the outer peripheral surface of the first gear 50. On the other hand, a plurality of teeth (not shown) are formed in the circumferential direction on the inner peripheral surface of the second gear 51. The teeth of the first gear 50 and the teeth of the second gear 51 mesh with each other. Thus, the first gear 50 and the second gear 51 fit together in the radial direction. In this example, the central axis of the cylindrical surface forming the outer peripheral surface of the motor shaft 49 is defined eccentrically from the rotation axis x in the region supporting the first gear 50. As a result, the rotational speed of the motor shaft 49 is reduced by a predetermined reduction ratio by the first gear 50 and the second gear 51.

[0019] The speed reducer 5 has a carrier 52 disposed on one side S1 in the rotational axis direction of the first gear 50 and the second gear 51. The carrier 52 is formed, for example, in a cylindrical shape around the rotation axis x. The carrier 52 is connected to the first gear 50 in the rotational axis direction. The carrier 52 is configured to reduce the rotational force of the motor shaft 49 by a predetermined reduction ratio via the first gear 50 and the second gear 51 and transmit it to an output shaft described later. The carrier 52 is supported on the outer peripheral surface of the motor shaft 49 via a bearing 13 on its inner peripheral surface, while being supported on the inner peripheral surface of the outer peripheral portion 21a of the gear housing 21 via a bearing 14 on its outer peripheral surface. The bearing 13 is a bearing having rolling elements, for example, a ball bearing. The bearing 14 is a bearing having rolling elements, for example, a needle bearing. Note that at least a part of the region including the meshing region of the teeth of the first gear 50 and the second gear 51 is covered with a fluid, that is, a lubricant (not shown). The lubricant is in contact with the wall 21b at least partially.

[0020] The speed reducer 5 has a cylindrical output shaft 53 around the rotation axis x. The output shaft 53 is arranged side by side with the motor shaft 49 in the rotation axis direction. The output shaft 53 is supported on the inner peripheral surface of the inner peripheral part 22b of the gear cover 22 via the bearing 15 on its outer peripheral surface, while it is supported on the outer peripheral surface of the crankshaft 3 via the bearing 16 on its inner peripheral surface. The inner peripheral surface of the carrier 52 facing each other and the outer peripheral surface of the output shaft 53 are connected via a one-way clutch 54. Similarly, the inner peripheral surface of the output shaft 53 facing each other and the outer peripheral surface of the crankshaft 3 are connected via a one-way clutch 55. Note that at least a part of the one-way clutches 54 and 55 is covered with a fluid, i.e., a lubricant (not shown). This lubricant is different from the lubricant covering the first gear 50 and the second gear 51.

[0021] The one-way clutches 54 and 55 can transmit the rotational force of the carrier 52 to the output shaft 53 in one direction around the rotation axis x (i.e., rotate the carrier 52 and the output shaft 53 in the same direction), while being configured to allow relative rotation between the carrier 52 and the output shaft 53 in the other direction around the rotation axis x. The end of the other side S2 of the output shaft 53 faces the motor shaft 49, while the end of the one side S1 of the output shaft 53 is arranged outside the gear cover 22. The end of the one side S1 of the output shaft 53 is connected to a chain ring fixed to the crank arm on the one side S1. Thus, the rotational force generated by the motor 4 is decelerated by the speed reducer 5 at a predetermined reduction ratio and transmitted from the output shaft 53 to the chain ring.

[0022] FIG. 4 is an enlarged cross-sectional view of a part of the cross-sectional view of FIG. 2. Referring to FIGS. 2 and 4 together, between the end face 45a on one side S1 of a predetermined member 45 covering the stator 40 of the motor 4 and the end face 21c on the other side S2 of the wall 21b of the gear housing 21, a member having thermal conductivity (hereinafter referred to as "thermal conductive member") 17 is disposed. The thermal conductive member 17 is formed of, for example, an adhesive having thermal conductivity, a resin material having a filler of a metal material having thermal conductivity such as a metal material, or a metal material having thermal conductivity such as aluminum or copper. The thermal conductive member 17 is, for example, annularly arranged around the rotation axis x and is in contact with both the predetermined member 45 and the wall 21b in the rotation axis direction. The thermal conductive member 17 preferably at least partially faces the coil 43 of the stator 40 in the rotation axis direction.

[0023] An example of the usage mode of the rotating device 1 as described above will be described. When a user of a bicycle in which the rotating device 1 is incorporated pedals the pedal to rotate the crank arm, the crankshaft 3 rotates around the rotation axis x. In this example, when viewed from one side S1, the crankshaft 3 rotates clockwise. When the torque sensor detects an increase in the torque acting on the crankshaft 3 equal to or greater than a predetermined threshold value, the control circuit of the printed circuit board 46 electrically connected from an external power source via another substrate supplies current to the coil 43 of the motor 4. Due to the magnetic interaction between the coil 43 and the magnet 47, the rotor 41 rotates relative to the stator 40 around the rotation axis x. The rotational force generated by this rotation is transmitted from the motor shaft 49 to the speed reducer 5. The rotor 41 and the motor shaft 49 rotate counterclockwise when viewed from one side S1.

[0024] In the speed reducer 5, rotational force is transmitted from the carrier 52 to the output shaft 53 while reducing the rotational speed by the engagement of the first gear 50 and the second gear 51. Note that due to the function of the speed reducer 5, the rotational direction of the motor shaft 49 is opposite to that of the output shaft 53. That is, when viewed from one side S1, the output shaft 53 rotates clockwise. The rotational force with the reduced rotational speed is transmitted from the output shaft 53 to the chain ring and the crankshaft 3. As a result, the rotational force of the motor 4 assists the rotation of the crank arm of the bicycle while increasing its torque. Thus, the user of the bicycle can easily pedal with the rotational force of the motor 4 even in situations where the torque is large.

[0025] In such a rotating device 1, the heat conductive member 17 is in contact with both the wall 21b crossing between the motor 4 and the speed reducer 5 arranged in the rotational axis direction and the stator 40 of the motor 4. In the motor 4, when an electric current is supplied to the coil 43, the coil 43 generates heat. The heat of the coil 43 is transmitted from a predetermined member 45 to the outer peripheral portion 20a of the motor housing 20 and then released to the external space. Similarly, the heat of the coil 43 is transmitted from a predetermined member 45 to the wall 21b via the heat conductive member 17. This heat is transmitted from the wall 21b to the outer peripheral portion 21a and then released to the external space. Thus, the heat dissipation performance of the motor 4 can be further enhanced by the heat conductive member 17.

[0026] Further, the second gear 51 of the speed reducer 5 is fixed to the gear housing 21. Also, the lubricant covering the portion where the first gear 50 and the second gear 51 mesh with each other is at least partially in contact with the wall 21b. Therefore, the heat of the coil 43 is directly or indirectly transmitted to the lubricant via a predetermined member 45, the wall 21b, and the first gear 50 and the second gear 51. As a result, the heat raises the temperature of the lubricant. For example, the temperature of the lubricant of the speed reducer 5 is raised immediately after the start of the rotating device 1. Due to this temperature rise, the fluidity of the lubricant increases, so that the lubricity of the lubricant can be improved. As a result, the operation of the speed reducer 5 can be stabilized immediately after the start. Note that the heat conductive member 17 may be in direct contact with the coil 43.

[0027] Note that although the rotating device 1 according to an embodiment of the present invention is incorporated in an electric assist bicycle, the rotating device 1 may be used for other applications such as industrial robots and machine tools instead of the electric assist bicycle. Further, although the speed reducer 5 described above constitutes a cycloid speed reducer as an example, it may be another type of speed reducer such as a harmonic gear speed reducer.

[0028] The embodiments described above are for facilitating the understanding of the present invention and are not for limiting and interpreting the present invention. Further, the above-described embodiments do not limit the objects to which the present invention is applied, and the present invention may include any object as its application target. Each component included in the above embodiments, as well as its arrangement, material, conditions, shape, size, etc. are not limited to those illustrated and can be changed as appropriate. For example, the present invention includes differences that occur in implementation such as manufacturing tolerances. Further, within a technically non-contradictory range, the components shown in different embodiments can be partially replaced or combined with each other. Also, each configuration can be appropriately and selectively combined so as to achieve at least a part of the above-described problems and effects.

Description of Reference Numerals

[0029] 1 Rotating machine, 10 Bearings, 11 Bearings, 12 Bearings, 13 Bearings, 14 Bearings, 15 Bearings, 16 Bearings, 17 Member having thermal conductivity (thermal conductivity member), 2 Housing, 20 Motor housing, 20a Outer portion (outer peripheral portion), 20b Inner portion (inner peripheral portion), 20c Wall, 21 Gear housing, 21a Outer portion (outer peripheral portion), 21b Wall, 22 Gear cover, 22a Outer portion (outer peripheral portion), 22b Inner portion (inner peripheral portion), 23 Fastening parts, 24 Annular member (gasket), 25 Annular member (gasket), 26 End cover, 27 Fastening parts, 3 Crankshaft, 3a One end, 3b The other end, 4 Motor, 40 Stator, 41 Rotor, 42 Magnetic body (stator core), 42a Magnetic pole portion (teeth), 43 Coil, 44 Insulator, 45 Predetermined member (resin), 45a End face, 46 Substrate (printed circuit board), 47 Magnet, 48 Magnetic body (yoke), 49 Motor shaft (shaft), 5 Reducer, 50 First gear (gear), 51 Second gear (gear), 52 Carrier, 53 Output shaft, 54 One-way clutch, 55 One-way clutch, S1 One side, S2 The other side, x Axis of rotation

Claims

1. a gear, a motor, a housing that houses the gear and the motor, a member having thermal conductivity, and the housing includes a wall that crosses between the gear and the motor arranged in the axial direction, in the axial direction, the member having thermal conductivity is in contact with the wall and the motor, a rotating device.

2. a part of the gear is covered by a fluid, and the gear is in contact with the housing directly or via another member, the rotating device according to claim 1.

3. a speed reducer having a plurality of gears including the gear, and the speed reducer is on the side opposite to the motor with respect to the wall, the rotating device according to claim 1 or 2.

4. the motor includes a stator having a coil, and the member having thermal conductivity is in contact with the stator, the rotating device according to any one of claims 1 to 3.

5. the stator is covered with resin, and the resin is in contact with the member having thermal conductivity, the rotating device according to claim 4.

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