Rotary apparatus

Abstract

To provide a rotary apparatus that can prevent leakage of lubricant with a small number of components.SOLUTION: A rotary apparatus 1 comprises: gears 50, 51; a motor 4 having a shaft 49 that supports the gears 50, 51; a housing 2 that accommodates the gears 50, 51 and the motor 4; and a sleeve 17. The housing 2 has a wall 21b that crosses the gears 50, 51 and the motor 4 arranged side by side in an axial direction. An inner peripheral part 21c of the wall 21b is connected to an outer peripheral surface of the shaft 49 with the sleeve 17 therebetween.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 including a gearbox having gears, and a motor connected to the gearbox. In this geared motor, the lubricant for the gears is sealed by an oil seal attached to the gearbox side, a collar press-fitted onto the shaft, or the like.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In this geared motor, when sealing the lubricant, a plurality of components are required, and space is required in the direction of the rotation axis of the motor.

[0005] Therefore, one of the problems of the present invention is to provide a rotating device capable of suppressing leakage of lubricant with a small number of component parts.

Means for Solving the Problems

[0006] A rotating device according to an aspect of the present invention includes a gear, a motor having a shaft that supports the gear, a housing that houses the gear and the motor, and a sleeve. The housing includes a wall that crosses between the gear and the motor arranged in the axial direction, and an inner peripheral portion of the wall is connected to an outer peripheral surface of the shaft via the sleeve.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Figure 3

Figure 4

MODE FOR CARRYING OUT 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 the rotating device 1 according to an embodiment of the present invention. FIG. 2 is a cross-sectional view taken along line 2-2 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, for example, an overall substantially cylindrical shape. The housing 2 is fixed to, for example, a bicycle frame. 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 project from the housing 2 in the rotation axis direction. Crank arms (not shown) extending in a direction orthogonal to the rotation axis x are respectively attached to the one end 3a and the other end 3b. 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 (second housing) 20 that houses the motor 4 (hereinafter referred to as the "motor housing"), a housing (first housing) 21 that houses the speed reducer 5 (hereinafter referred to as the "gear housing"), and a cover (hereinafter referred to as the "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. The space between the motor housing 20 and the gear housing 21 is sealed by an annular member (hereinafter referred to as the "gasket") 24. The space between the gear housing 21 and the gear cover 22 is sealed by an annular member (hereinafter referred to as the "gasket") 25. Note that the housing 2 is formed of, for example, a metal material or a resin material. From the viewpoint of thermal conductivity, it is preferable that the motor housing 20 and the gear housing 21 are 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 the "outer peripheral portion") 20a centered on the rotational axis x, a cylindrical inner portion (hereinafter referred to as the "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. In this example, the wall 20c extends along a virtual plane orthogonal to the rotational axis x. That is, the wall 20c faces the motor 4 in the rotational axis direction and forms a bottom.

[0012] A bearing (first 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 protrudes from the housing 2 to the other side S2 through a hole (through hole) of the end cover 26 formed along the rotational axis x.

[0013] FIG. 3 is a cross-sectional view taken along line 3-3 of FIG. 2. Referring to FIGS. 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 a "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 in the circumferential direction 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 "printed circuit board") 46 is fixed to the other side S2 of the predetermined member 45, and 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. This printed circuit board 46 is electrically connected to, for example, the outer peripheral surface of the rotating device 1 or another substrate provided outside. Further, the printed circuit board 46 may be configured by 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. Current is supplied to the coil 43 from, for example, a battery (not shown) mounted on a bicycle. Thus, 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 "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 pole portion (hereinafter referred to as "tooth") 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. Further, 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 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 20b. In the gear housing 21, a speed reducer 5 described later is connected to the end 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 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 (second 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. In this way, 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 in a cylindrical shape around the rotation axis x, for example. The carrier 52 is connected to the first gear 50 in the rotational axis direction. The carrier 52 is configured to decelerate 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 W.

[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 portion 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, that is, a lubricant (not shown). This lubricant is different from the lubricant W that covers 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 (that is, 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, the wall 21b of the gear housing 21 has an annular inner peripheral side end portion (hereinafter referred to as "inner peripheral portion") 21c. An annular sleeve 17, for example, is sandwiched between this inner peripheral portion 21c and the motor shaft 49. The inner peripheral portion 21c is connected to the motor shaft 49 via the sleeve 17. That is, the sleeve 17 is disposed between the rotor 41 and the bearing 12 in the rotational axis direction. In this example, the sleeve 17 is a cylindrical member having a constant length along the rotational axis direction. The sleeve 17 is supported, for example, by press-fitting on the inner peripheral surface of the inner peripheral portion 21c. The inner peripheral surface of the sleeve 17 supports the outer peripheral surface of the motor shaft 49 so as to be relatively rotatable.

[0023] The sleeve 17 is, for example, a sintered bearing formed of sintered metal. In this example, the sleeve 17 is a bearing formed by impregnating the pores of the sintered metal with a fluid, i.e., a lubricant. This lubricant may have the same composition as the lubricant W filled in the meshing region of the teeth of the first gear 50 and the second gear 51 of the speed reducer 5, or may have a composition that repels the lubricant W. A lubricant is disposed between the outer peripheral surface of the sleeve 17 and the inner peripheral surface of the inner peripheral portion 21c, and between the inner peripheral surface of the sleeve 17 and the outer peripheral surface of the motor shaft 49. Thus, the sleeve 17 constitutes a so-called sliding bearing. Note that, instead of the bearing impregnated with the lubricant, a bearing not impregnated with the lubricant may be used for the sleeve 17.

[0024] An example of the usage mode of the rotating device 1 as described above will be explained. When a user of a bicycle equipped with the rotating device 1 pedals 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, which is 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.

[0025] In the speed reducer 5, the 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 rotation direction of the motor shaft 49 is opposite to the rotation direction 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. In this way, the user of the bicycle can easily pedal even in a situation where the torque is large by the rotational force of the motor 4.

[0026] In such a rotating device 1, a sleeve 17 is disposed between the inner peripheral portion 21c of the wall 21b and the motor shaft 49. The sleeve 17 supports the motor shaft 49 in a relatively rotatable manner. As a result, the wall 21b and the sleeve 17 can prevent the lubricant W covering at least a part of the speed reducer 5 from scattering or leaking from the speed reducer 5 side to the motor 4 side. Further, since the wall 21b of the housing 2 and the sleeve 17 extend in the radial direction, no space is required in the rotational axis direction. Further, since the sleeve 17 is attached to the wall 21b of the housing 2, the number of components can be reduced in preventing the scattering or leakage of the lubricant W.

[0027] Moreover, on the motor 4 side, due to the heat generation of the coil 43, a positive pressure is generated in the motor housing 20 in which the motor 4 is accommodated. The generated positive pressure acts on the lubricant W that tries to leak from the gear housing 21 in which the speed reducer 5 is accommodated to the motor housing 20 side through the space between the inner peripheral surface of the sleeve 17 and the outer peripheral surface of the motor shaft 49. As a result, the leakage of the lubricant W from between the inner peripheral surface of the sleeve 17 and the outer peripheral surface of the motor shaft 49 to the motor 4 side can be reliably suppressed. In addition, since the sleeve 17 functions as a sliding bearing that supports the motor shaft 49, it can also function to suppress the shaft vibration of the motor shaft 49.

[0028] 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, other types of speed reducers such as a harmonic gear speed reducer may be used.

[0029] The embodiments described above are for facilitating the understanding of the present invention and are not for limiting and interpreting the present invention. Also, the above-described embodiments do not limit the objects to which the present invention is applied, and the present invention can 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 exemplified and can be changed as appropriate. For example, the present invention includes differences that occur in the implementation such as manufacturing tolerances. Also, 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 selectively combined as appropriate so as to achieve at least part of the above-described problems and effects.

Explanation of Reference Numerals

[0030] 1 Rotating device, 10 Bearing (first bearing), 11 Bearing, 12 Bearing (second bearing), 13 Bearing, 14 Bearing, 15 Bearing, 16 Bearing, 17 Sleeve, 2 Housing, 20 Motor housing (second housing), 20a Outer portion (outer peripheral portion), 20b Inner portion (inner peripheral portion), 20c Wall, 21 Gear housing (first housing), 21a Outer portion (outer peripheral portion), 21b Wall, 21c Inner peripheral side end (inner peripheral portion), 22 Gear cover, 22a Outer portion (outer peripheral portion), 22b Inner portion (inner peripheral portion), 23 Fastening part, 24 Annular member (gasket), 25 Annular member (gasket), 26 End cover, 27 Fastening part, 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, 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, W Lubricant, x Axis of rotation

Claims

1. a gear, a motor having a shaft for supporting the gear, a housing for accommodating the gear and the motor, and a sleeve, comprising: the housing includes a wall that crosses between the gear and the motor arranged axially; a rotating device, wherein an inner peripheral portion of the wall is connected to an outer peripheral surface of the shaft via the sleeve.

2. comprising a speed reducer having the gear, wherein the speed reducer is on the opposite side of the motor with respect to the wall axially, the rotating device according to Claim 1.

3. the housing includes an outer portion surrounding the motor and an inner portion inside the motor; a rotating device according to Claim 1 or 2, wherein the inner portion supports the shaft via a first bearing radially.

4. the shaft rotates with respect to the wall, a rotating device according to any one of Claims 1 to 3, wherein there is fluid between the sleeve and the shaft or between the sleeve and the inner peripheral portion of the wall.

5. a rotating device according to any one of Claims 1 to 4, wherein the motor includes a rotor connected to the shaft and a stator facing the rotor radially.

6. the gear is connected to the shaft via a second bearing, a rotating device according to Claim 5, wherein the sleeve is axially between the second bearing and the rotor.

7. the housing includes a first housing for accommodating the gear and a second housing for accommodating the motor; a rotating device according to any one of Claims 1 to 6, wherein the first housing includes the wall.

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