JPH10225053A - Motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to transmit a reduced rotating speed of a motor and thereby simplify the structure and reduce the size of a power transmitting system by installing a one-way clutch for transmitting power only to the output side between a stator and a rotor which faces the stator. SOLUTION: An output shaft 17 rotatably supports a rotor 20 in the outer periphery through bearings 21, 22. In the rotor 20, a one-way clutch 25 is installed between the output shaft 17 and a yoke 23. The one-way clutch 25 has such a structure that it may transmit power only when a motor 3 is turning in the forward direction. In the case that the motor is stopped at a speed exceeding a limitation speed for helping electric driving or a vehicle runs when the motor 3 is not supplied with power, rotating torque of a pedal crank shaft 2 is transmitted from a resultant shaft 7 also to the output shaft 17 of the motor 3 through a speed reducer 27, however there is no increase in load since the one-way clutch 25 is in an uncoupled state. As a result, a small capacity one-way clutch can be used and thereby the structure of a power transmitting system can be simplified and the size is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric motor having a one-way clutch.

[0002]

2. Description of the Related Art Conventionally, an electric bicycle using an electric motor as an auxiliary power source (see, for example, Japanese Patent No. 2506047).
In, the rotation of the motor is greatly reduced by a speed reducer in order to match the rotation of the brushed DC motor with the rotation of the human power drive system. The reduction gear of the electric bicycle disclosed in the publication includes a first-stage planetary roller reduction gear having a structure in which a sun roller rotates together with an output shaft of the motor, and a planetary roller support as an output member of the planetary roller reduction gear. And a second-stage speed reducer composed of a bevel gear and a ring gear connected to the carrier.

Further, in this electric bicycle, in order to prevent the electric motor from being dragged by itself and becoming a resistance when the electric bicycle is driven only by human power without using the electric motor, a one-way power transmission system is provided. The clutch is interposed. The one-way clutch is disposed between the planetary roller supporting carrier and the bevel gear in the power transmission system. That is, the one-way clutch is disposed at a portion where the rotation of the electric motor is transmitted while being reduced.

[0004]

However, if a one-way clutch is interposed at a portion where the rotation of the electric motor is transmitted while being decelerated, a rotational torque increased by the reduction ratio acts on the one-way clutch. Therefore, a one-way clutch having a relatively large capacity must be used. That is, since a large one-way clutch must be provided in the power transmission system of the electric motor, not only the configuration of the power transmission system becomes large, but also the weight becomes heavy. Such a problem occurs not only in the electric bicycle drive device but also in most drive devices having a structure in which a speed reducer and a one-way clutch are interposed in the power transmission system of the electric motor.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and it is intended to reduce the transmission of rotation of an electric motor while interposing a one-way clutch having a small capacity,
An object of the present invention is to simplify and reduce the size of a power transmission system.

[0006]

An electric motor according to the present invention comprises:
A one-way clutch for transmitting power only from the rotor to the output shaft is interposed between the output shaft and a rotor mounted on the output shaft and facing the stator. According to the present invention, a one-way clutch can be provided at a portion of the power transmission system that rotates at the highest speed. For this reason, the rotational torque acting on the one-way clutch becomes the smallest in the power transmission system of the electric motor, so that a one-way clutch with a small capacity can be used.

According to another aspect of the present invention, there is provided an electric motor having a sun gear rotating with the rotor, and a planetary gear support rotating with the output shaft, between an output shaft penetrating the housing and a rotor facing the stator. A planetary gear reducer including a carrier for the vehicle, and a one-way clutch having a structure in which power is transmitted only from the sun gear to the carrier side between the outer peripheral gear of the planetary gear reducer and the housing. It was interposed.

When the one-way clutch regulates the rotation of the outer peripheral gear, the rotational torque acting on the one-way clutch is:
Since it is substantially equal to the rotational torque transmitted from the sun gear to the planetary gear, it becomes the smallest in the power transmission system of this electric motor. Therefore, according to the present invention, a one-way clutch having a small capacity can be used.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION

First Embodiment Hereinafter, an embodiment of an electric motor according to the present invention will be described in detail with reference to FIG. Here, an example of a driving device for an electric bicycle using the electric motor according to the present invention as an auxiliary power source will be described.

FIG. 1 is a sectional view of an electric bicycle driving device incorporating an electric motor according to the present invention. In the figure, reference numeral 1 denotes an electric bicycle driving device according to the present embodiment. The driving device 1 transmits a driving force obtained by combining the manual power applied to the pedal crankshaft 2 and the power of the electric motor 3 according to the present invention to the rear wheel driving sprocket 4, and drives a rear wheel (not shown). It has a structure. The drive device 1 detects the force of stepping on a pedal (not shown) as a rotational torque of the pedal crankshaft 2 by a torque sensor described later, and increases or decreases the output of the electric motor 3 according to the stepping force. .

The pedal crankshaft 2 is formed so that a pedal-equipped crank (not shown) can be attached to both ends, and the drive unit housing 5 is arranged so that the axial direction is directed to the left and right direction of the vehicle body (not shown). It is supported rotatably. The drive device housing 5 is fixed to a vehicle body frame (not shown) of the electric bicycle. The left side of the pedal crankshaft 2 is supported by the drive unit housing 5 via a bearing 6, and the right side of the vehicle body is supported by the drive unit housing 5 via a resultant shaft 7 through which the pedal crankshaft 2 passes and bearings 8 and 9. Let me. The resultant shaft 7 has a small-diameter portion 7a that supports the pedal crankshaft 2 via the bearing 8 and protrudes laterally from the drive device housing 5, and the rear wheel driving sprocket 4 is fixed to a distal end portion. The sprocket 4 winds a chain (not shown) between the sprocket and the rear wheel sprocket.

The pedal crankshaft 2 has a one-way clutch 1 at a position on the right side of the vehicle body from the center in the axial direction.
The large-diameter portion 7b of the resultant force shaft 7 is connected to the large-diameter portion 7b.
The one-way clutch 10 is of a ratchet type, and is formed so that rotation is transmitted only from the pedal crankshaft 2 to the resultant shaft 7 side.

In order to detect the rotational torque of the pedal crankshaft 2, a non-contact magnetostrictive torque sensor indicated by reference numeral 11 in the figure is used. The torque sensor 11 includes spiral inclined grooves 12, 12... Engraved on the outer peripheral surface of the pedal crankshaft 2 on the left side of the vehicle body, and an exciting coil 13 provided to cover the periphery of the inclined grooves 12. It comprises a detection coil 14 and the like. A large number of the inclined grooves 12 are arranged in the circumferential direction of the pedal crankshaft 2 and are formed at two positions in the axial direction of the pedal crankshaft 2. Further, the inclined grooves 12 of these two inclined groove groups are formed such that the inclination direction is symmetric with respect to the axis.

Here, the operation of the torque sensor 11 will be described. When the pedal crankshaft 2 is twisted, a tensile stress is generated in one inclined groove group, and a compressive stress is generated in the other inclined groove group. As a result, the magnetic permeability in each inclined groove group increases and decreases due to the inverse magnetostriction effect. A change in the magnetic permeability due to the inverse magnetostriction effect is generated as an induced electromotive force in the detection coils 14 for each of the inclined groove groups, and this is DC-converted and differentially amplified by a controller (not shown), thereby outputting a voltage proportional to the torque. Is obtained. At this time, the detected output voltage from the coil system increases because of the permeability increase due to the tensile stress in the inclined groove group where the tensile stress occurs, and the detection from the coil system due to the decrease in the magnetic permeability due to the compressive stress in the other inclined groove group. The output voltage decreases. The controller employs a circuit for increasing and decreasing the supply current of the electric motor 3 according to the change in the output voltage. Note that this controller is configured so that the output of the electric motor becomes 0 when the traveling speed of the vehicle body exceeds the electric assist limit speed defined by law.

The electric motor 3 is a brushless DC motor, and is assembled inside the electric motor housing 3a comprising the driving device housing 5 and the cover 15 connected thereto so that the axial direction coincides with the left and right direction of the vehicle body. I have. The stator 16 of the electric motor 3 has a conventionally well-known structure including an iron core 16a and a coil 16b, and is fixed in the electric motor housing 3a to the drive device housing 5 side. The output shaft 17 is rotatably supported by the drive device housing 5 and the cover 15 by bearings 18 and 19.

A rotor 20 is rotatably supported on the outer peripheral portion of the output shaft 17 via bearings 21 and 22. The rotor 20 includes a cylindrical yoke 23 and a permanent magnet 24 fixed to an outer peripheral surface of the yoke 23.
A one-way clutch 25 is interposed between the yoke 7 and the yoke 23.

The output shaft 17 has an output gear 26 formed at the tip on the right side of the vehicle body, and is connected to the resultant shaft 7 via a helical gear type reduction gear 27 which meshes with the output gear 26. The reduction gear 27 is formed on a first gear 28 that meshes with the output gear 26, a reduction gear shaft 29 that supports the first gear 28 and rotates at the same rotation speed as the first gear 28, and a reduction gear shaft 29. And a third gear 31 formed on the large diameter portion 7b of the resultant shaft 7 and meshing with the second gear 30. That is, the speed reducer 27 adopts a structure in which the rotation of the output shaft 17 is reduced to two stages and transmitted to the resultant shaft 7.

The permanent magnet 24 is formed of a rare earth magnet material and is opposed to the inner surface of the stator 16 with a small gap. In the present embodiment, a one-way clutch 25 interposed between the yoke 23 and the output shaft 17 uses a roller type one. When the electric motor 3 rotates forward, that is, the stator 16 Power is transmitted only when the yoke 24 and the yoke 23 are urged in the forward direction of the vehicle. The one-way clutch 25
The roller may be of various structures such as a ratchet type in addition to the roller type. However, a large type which cannot secure the thickness of the yoke 23 is avoided. This is because if the yoke 23 is thin, magnetic leakage to the one-way clutch 25 will occur and the output performance of the electric motor 3 will be reduced.

In the motor 3 configured as described above, when the coil 16b of the stator 16 is excited with a voltage corresponding to the force of depressing the pedal, the rotation torque is applied to the rotor 20 including the yoke 23 and the permanent magnet 24. Occurs. This rotor 2
The rotation of 0 is transmitted to the output 17 via the one-way clutch 25, and transmitted from the output shaft 17 to the resultant shaft 7 via the speed reducer 27. Then, the resultant force obtained by adding the power of the electric motor 3 to the pedaling force (the rotational torque of the pedal crankshaft 2) is transmitted from the resultant shaft 7 to the rear wheels via the sprocket 4 and the rear wheel drive chain. A known freewheel is interposed between the rear wheel and the rear wheel-side sprocket so that the vehicle can coast freely without stepping on the pedal.

When the running speed of the vehicle body exceeds the electric assist limit speed defined by law and the motor 3 is stopped, or when the vehicle runs without supplying power to the motor 3, the rotational torque of the pedal crankshaft 2 is reduced. The power is also transmitted from the resultant shaft 7 to the output shaft 17 of the electric motor 3 via the speed reducer 27. However, at this time, since the one-way clutch 25 in the electric motor 3 is in the non-coupled state, the load does not increase due to the yoke 23 and the permanent magnet 24 being rotated together with the human-powered drive system having the pedal crankshaft 2. .

Therefore, the electric motor 3 is connected to the rotor 20
Between the yoke 24 and the output shaft 17 from the yoke 24 to the output shaft 1
Since the one-way clutch 25 that transmits power only to the side 7 is interposed, the one-way clutch 25 can be disposed at the portion of the power transmission system of the electric motor 3 that rotates at the highest speed. For this reason, the one-way clutch 25 may transmit a smaller rotational torque compared to the case where the one-way clutch 25 is interposed in a decelerated portion, and may use a small-capacity clutch that has a small occupied space and a relatively light weight. Can be used.

Further, the electric motor 3 shown in this embodiment
Is a brushless DC motor in which the permanent magnet 24 is formed of a rare-earth magnet material (an AC synchronous motor that is easy to be a low-speed and high-torque type compared to a DC motor with a brush). The reduction ratio can be reduced as compared with a motor using a motor. That is, as compared with a drive device for an electric bicycle using a DC motor with a brush, the drive device 1 may reduce the reduction ratio, and for example, reduces the output of the motor in three stages and guides the output to the resultant shaft, for example. This can be reduced to two stages as in the present embodiment, so that the power transmission system can be simplified and downsized, the drive efficiency can be improved, and the noise generated by the gears can be reduced. .

Second Embodiment An electric motor according to another embodiment of the present invention will be described in detail with reference to FIG. In this embodiment, an example will be described in which an electric motor according to another invention is applied to a driving device for an electric bicycle that can run only by the power of the electric motor. FIG. 2 is a sectional view of an electric bicycle drive device incorporating an electric motor according to another invention. In this figure, the same or equivalent members as those described in FIG. 1 are denoted by the same reference numerals, and detailed description is omitted.

An electric motor indicated by reference numeral 41 in FIG. 2 has a structure in which the output is increased or decreased by an accelerator device (not shown) provided on a handle portion, and an axial center of a housing 42 fixed to a body frame (not shown) of the electric bicycle. Through the pedal crankshaft 2 and the pedal crankshaft 2
, A stator 16 and a rotor 43 are arranged.
At one shaft end of the pedal crankshaft 2, a manual drive sprocket 44 for transmitting pedaling force to the rear wheel is mounted. The sprocket 44 is connected to a rear wheel via a manual drive system having a chain and a freewheel (not shown). The pedal crankshaft 2 is rotatably supported on one side in the axial direction by a housing 42 by a bearing 6, and the other is provided on bearings 8 and 9 and an output shaft 44 described later.
The housing 42 is rotatably supported by the housing 42.

The output shaft 44 is provided coaxially with the pedal crankshaft 2 and passes through the housing 42. The rotor 43 includes a cylindrical yoke 23 rotatably supported via bearings 45 and 46 on a cylindrical portion 42 a of the housing 42 through which the pedal crankshaft 2 is inserted, and the yoke 2.
3 and a permanent magnet 24 opposed to the inner peripheral surface of the stator 16 with a small gap between the inner peripheral surface of the stator 16 and a planetary gear reducer 47 between the rotor 43 and the output shaft 44. It is interposed. A rear wheel drive sprocket 4 is attached to the output shaft 44.
So that the rotation of the output shaft 44 is transmitted to the rear wheels via a rear wheel drive chain (not shown). The power transmission system having this chain does not include a one-way clutch.

The planetary gear reducer 47 is provided with the yoke 23
And a plurality of planetary gears 49 meshing with the sun gear 48, an outer peripheral gear 50 disposed outside the sun gear 48 and the planetary gear 49 and meshing with the planetary gear 49. , The support arm 44 of the output shaft 44
a and a carrier 51 which is provided at a and rotatably supports the planetary gears 49.

The outer peripheral gear 50 is formed by carving teeth on the inner peripheral surface of the annular body, and is attached to the housing 42 via a one-way clutch 52. The one-way clutch 52 has a conventionally well-known structure such as a ratchet type or a roller type, and is provided in several places along the outer periphery of the outer peripheral gear 50. Power is transmitted only to the vehicle.

The electric motor 41 thus configured is configured such that when the coil 16b of the stator 16 is excited, the yoke 2
Rotation torque is generated in the rotor 43 including the permanent magnet 3 and the permanent magnet 24. The rotation of the rotor 43 is controlled by the planetary gear reducer 4.
The transmission is transmitted to the output shaft 44 via the output shaft 7 and transmitted to the rear wheels from the output shaft 44 via the rear wheel driving sprocket 4 and the chain wound around the sprocket.

When traveling downhill or when the electric motor 41 is not energized, the output shaft 44 that rotates with the rear wheels exceeds the rotation of the sun gear 48.
However, at this time, the one-way clutch 52 in the electric motor 41 is disengaged and the outer peripheral gear 50 rotates in accordance with the rotation of the output shaft 44, so that the sun gear 48 and the yoke together with the output shaft 44 and the carrier 51. 23, the permanent magnet 24 and the like do not rotate, and they do not become resistance. That is, the electric bicycle using the electric motor 41 has a low resistance when the electric motor 41 is stopped and the vehicle runs by inertia. Therefore, when the vehicle body goes down the slope, the power supply to the electric motor 41 is cut off to save battery power. can do.

Further, since the resistance is small when the vehicle is running by inertia, by intermittently energizing the electric motor 41 when running on level ground, the vehicle can run while utilizing the inertia force of the vehicle body. . That is, by adopting this traveling method, the distance (cruising distance) that can be traveled with one charge can be extended as much as possible.

When the one-way clutch 52 regulates the rotation of the outer peripheral gear 50, the rotational torque acting on the one-way clutch 52 is substantially equal to the rotational torque transmitted from the sun gear 48 to the planetary gear 49. 41 is the smallest among the power transmission systems. Therefore, since the one-way clutch 52 having a small capacity can be used, the space occupied by the one-way clutch 52 can be reduced, and the one-way clutch 52 having a relatively light weight can be used.

Further, the electric motor 41 shown in this embodiment
Is a brushless DC motor (a low-speed high-torque AC motor) in which the permanent magnet 24 is formed of a rare-earth magnet material. As a result, the reduction ratio can be reduced. That is, in the electric bicycle using the electric motor 41, the power transmission system can be simplified and downsized by reducing the reduction ratio as compared with the case of using a brushed DC motor, and the driving efficiency is improved. Also, noise generated from the gears can be reduced.

The electric motor 41 shown in this embodiment
Has a structure in which the vehicle can run by depressing a pedal, but the pedal crankshaft 2 is eliminated and a fixed shaft is inserted in place of the pedal crankshaft. It can also be configured to run. Further, the pedal crankshaft 2 is eliminated and a rear wheel axle is inserted in place of the pedal crankshaft 2.
A rear wheel hub may be connected to the sprocket 4 instead of the sprocket 4.

Further, in the above two embodiments,
Although the example in which the electric motor according to the present invention is applied to the electric bicycle has been described, the present invention is not limited to such a limitation, and the present invention can be applied to an electric motor used in any device. Furthermore, in the above-described two embodiments, the rotor is an inner rotor type.
The present invention can also be applied to an outer rotor type in which a stator is provided inside and a rotor is provided outside, and a flat rotor type used in a flat electric motor.

[0035]

The electric motor according to the present invention has a structure in which an output shaft and a rotor mounted on the output shaft and facing the stator are disposed between the output shaft and the rotor.
Since a one-way clutch for transmitting power only from the rotor to the output shaft is interposed, the one-way clutch can be disposed at a portion of the power transmission system that rotates at the highest speed.

Accordingly, since the rotational torque applied to the one-way clutch is the smallest in the power transmission system, a one-way clutch having a small capacity can be used. Therefore, the space occupied by the one-way clutch can be reduced, and a one-way clutch having a relatively light weight can be used, so that the configuration of the power transmission system can be simplified and downsized. .

According to another aspect of the present invention, there is provided an electric motor having a sun gear rotating with the rotor and a planetary gear support rotating with the output shaft between an output shaft penetrating the housing and a rotor facing the stator. A one-way clutch having a structure in which a planetary gear reducer including a carrier for a vehicle is interposed, and power is transmitted only from the sun gear to the carrier side between the outer peripheral gear of the planetary gear reducer and the housing. The rotation torque acting on the one-way clutch when the one-way clutch regulates the rotation of the outer peripheral gear is substantially equal to the rotation torque transmitted from the sun gear to the planetary gear, and the power transmission system of the electric motor is provided. Among the smallest.

Therefore, a one-way clutch having a small capacity can be used, so that the space occupied by the one-way clutch can be reduced, and a relatively light one-way clutch can be used. The configuration of the system can be simplified and downsized.

[Brief description of the drawings]

FIG. 1 is a sectional view of an electric bicycle drive device incorporating an electric motor according to the present invention.

FIG. 2 is a sectional view of an electric bicycle drive device incorporating an electric motor according to another invention.

[Explanation of symbols]

2: pedal crankshaft, 3, 41: electric motor, 16: stator, 17: output shaft, 20: rotor, 23: yoke, 24 ...
Permanent magnet, 25, 52 one-way clutch, 42 housing, 43 rotor, 44 output shaft, 47 planetary gear reducer, 48 sun gear, 49 planetary gear, 50 peripheral gear, 51 carrier .

Claims (2)

[Claims] 1. A one-way clutch for transmitting power only from the rotor to the output shaft is interposed between the output shaft and a rotor mounted on the output shaft and facing the stator. An electric motor characterized in that: 2. A sun gear rotates with the rotor between an output shaft penetrating the housing and a rotor opposed to a stator in the housing, and a carrier supporting a planetary gear rotates with the output shaft. A planetary gear reducer having a structure to be interposed is provided, and an outer peripheral gear meshing with the planetary gear in the planetary gear reducer is connected to the housing via a one-way clutch. A motor in which power is transmitted only from a sun gear to the carrier side.