JP2020188676A - Rotary electric machine and in-wheel motor using the same - Google Patents

Abstract

To provide a compact rotary electric machine which can smoothly drive a movement mechanism with a reduced component weight.SOLUTION: The rotary electric machine includes: a stator having a stator core on which an armature coil is wound; and a rotor having a magnet which is freely rotatably arranged by the intermediary of a predetermined gap to the stator to face the stator. The stator is attached to a movement mechanism which is movable in a revolving shaft direction. At least an opposite face of the magnet out of mutually opposite faces of the magnet and the stator core is formed in a sectional stepwise shape which expands to the radial direction along the movement direction of the stator, and a larger space than the gap is formed between a corner part of the magnet and the stator core.SELECTED DRAWING: Figure 3

Description

The present invention relates to a rotary electric machine having a magnetic flux variable mechanism and an in-wheel motor using this rotary electric machine.

Conventionally, there is known a rotary electric machine capable of obtaining output characteristics according to the rotation speed by adjusting the output of the rotary electric machine at low speed and high speed. Various structures are known for such a rotary electric machine. For example, in the axial direction of the stator, the rotor provided coaxially with the stator and rotatably provided, and the stator with respect to the stator. A rotary electric machine is known which has a moving means for changing the relative position of the stator, an armature coil and a core are provided on the stator, and a magnet is provided so as to face the core.

According to such a rotating electric machine, at low speed rotation, the stator is moved in the axial direction by a moving mechanism so that the facing area between the stator and the rotor becomes large so that the effective magnetic flux passing through the stator becomes large. At the time of high-speed rotation, the stator is moved so as to reduce the facing area between the stator and the rotor so that the effective magnetic flux passing through the stator becomes small, and high-speed rotation is realized. There is.

Further, various forms are known in order to further increase the variable range of the output characteristic as the stator moves along the axial direction. For example, as shown in FIG. 5, as the stator 111 moves, the facing surfaces of the stator 111 and the magnet 114 are formed in a stepped shape in order to reduce the area where the stator 111 and the magnet 114 face each other. The magnetic flux acting on the stator 111 with the axial movement of the stator 111 is effectively reduced to increase the variable range of the output characteristics.

Japanese Unexamined Patent Publication No. 2008-141900

However, according to the conventional rotary electric machine, when the magnet 114 of the rotor is formed in a stepped shape and the stator 111 is moved so as to be inserted and removed from the rotor by a moving mechanism, the stator 111 is inserted and removed during the insertion and removal operation. It was found that the attractive force increased when the corners of the magnet 114 and the magnet 114 were facing each other.

If the suction force increases during the insertion / removal operation of the stator 111 in this way, it is necessary to output the output of the drive device that drives the moving mechanism against the suction force, which increases the size and weight of the drive device. There was a problem that it would lead to an increase in the number of people.

The present invention has been made to solve the above problems, and is a rotary electric motor capable of reducing the size of the rotary electric motor, reducing the weight of parts, and smoothly driving the moving mechanism, and the rotation thereof. An object of the present invention is to provide an in-wheel motor using an electric machine.

The rotary electric machine according to the present invention for solving the above problems is rotatably arranged with respect to a stator having a stator core around which an armature coil is wound and the stator through a predetermined gap, and is placed on the stator. In a rotary armature including a rotor having opposing magnets, the stator is attached to a moving mechanism that is movable in the direction of the axis of rotation, and the magnets and the stator cores facing each other move the stator. It is formed in a stepped cross section extending in the radial direction along the direction, and is characterized in that a space larger than the gap is formed between the corner portion of the magnet and the stator core.

According to the rotary electric machine according to the present invention, the stator core of the stator facing each other and the facing surface of the magnet of the rotor are formed in a stepped shape, and the corners of the stepped shape of the magnet are chamfered. When inserting and removing, the increase in attractive force due to the corners of the stator core and magnet facing each other is suppressed, and the drive device, etc. that constitutes the moving mechanism is made smaller and lighter to reduce the size and weight of the rotary electric machine. Can be done.

A cross-sectional view of a rotary electric machine according to an embodiment of the present invention. The cross-sectional perspective view which shows the sectional state of the stator and the rotor of the rotary electric machine which concerns on embodiment of this invention. FIG. 2 is an enlarged view of part A in FIG. The figure which shows the modification of the stator core. The graph which shows the relationship between the pull-out amount and the attractive force with respect to the magnet of the stator core which concerns on embodiment of this invention and the stator core of a comparative example. The cross-sectional view which shows the form of the stator core and the magnet of the comparative example.

Hereinafter, embodiments of the rotary electric machine according to the present invention will be described with reference to the drawings. It should be noted that the following embodiments do not limit the invention according to each claim, and not all combinations of features described in the embodiments are essential for the means for solving the invention. ..

FIG. 1 is an axial sectional view of a rotary electric machine according to an embodiment of the present invention, and FIG. 2 is a sectional perspective view showing a cross-sectional state of a stator and a rotor of the rotary electric machine according to the embodiment of the present invention. 3 is an enlarged view of part A in FIG. 2, FIG. 4 is a view showing a modified example of the stator core, and FIG. 5 is a drawing of the stator core according to the embodiment of the present invention and the stator core of the comparative example with respect to the magnet. It is a graph which shows the relationship between the difference amount and the attractive force, and FIG. 6 is a cross-sectional view which shows the form of the stator core and the magnet of the comparative example.

As shown in FIG. 1, the rotary electric machine 10 according to the present embodiment is preferably used as a so-called in-wheel motor incorporated in a wheel 1 of an automobile or the like. The wheel 1 includes an axle 4 that is attached to the vehicle body of an automobile and rotatably supports the wheel 1, and a tire 2 that is attached to the wheel 3 and an elastic body such as rubber attached to the outer peripheral surface of the wheel 3. ..

The rotary electric machine 10 according to the present embodiment is arranged inside the wheel 3, and by transmitting the rotational force of the rotary electric machine 10 to the wheel 3, the driving force of the automobile to which the rotary electric machine 10 is attached is generated. There is.

The wheel housing 15 is a hollow disk-shaped member, and is assembled so as to sandwich a flange portion extending in the radial direction of the back yoke 13. Further, a moving mechanism 20 described later is housed inside the wheel housing 15. Further, the wheel housing 15 is rotatably assembled with respect to the axle 4 by hub members 16 assembled at both ends in the axial direction.

Further, the stator 11 is attached to a moving mechanism 20 that can move in the axial direction of the axle 4. In the moving mechanism 20, the axle 4 is arranged coaxially with the rotation center axis of the stator 11, and the ball spline nut member 24 is rotatably assembled to the outer peripheral surface of the axle 4 and rotatably assembled to the outer peripheral surface of the axle 4. The ball screw nut member 25 is provided.

Further, the ball screw nut member 25 is configured so that a rotational force is applied by a drive motor 27 as a drive source to which a gear 28 is attached to the output shaft. With this configuration, the gear 28 rotates as the drive motor 27 rotates, and the gear 28 meshes with the outer peripheral surface of the ball screw nut member 25 to bring the drive motor 27 to the ball screw nut member 25. It transmits the rotational force.

Further, the axle 4 is a hollow shaft in which a through hole 21 is formed in the axial direction, and a ball spline groove (not shown) formed along the axial direction is formed on one end side in the axial direction of the outer surface and is formed on the other end side. A spiral ball screw groove 23 is formed. The ball spline groove and the ball screw groove 23 are formed adjacent to each other so as to overlap each other in the vicinity of the center of the axle 4.

Further, a pair of rolling grooves 29, 29 on which a rolling element, which will be described later, can roll are formed on the outer surface of the axle 4. The rolling groove 29 is formed along the circumferential direction of the axle 4, and is formed on the axial end side of the axle 4. That is, the rolling groove 29 is arranged on the shaft end side of each of the ball spline groove and the ball screw groove 23, and the ball spline groove and the ball screw groove 23 are arranged between the pair of rolling grooves 29. There is.

The ball spline nut member 24 is a cylindrical member, and the axle 4 is inserted into the inner circumference thereof. Further, a second ball spline groove corresponding to the ball spline groove of the axle 4 is formed on the inner peripheral surface of the ball spline nut member 24, and is not shown between the ball spline groove and the second ball spline groove. The ball spline nut member 24 is movably assembled in the axial direction of the axle 4 by interposing a rolling element or the like. Further, one end of the ball spline nut member 24 is inserted into the inner ring of the bearing 26 and is attached to the moving base 30 of the stator 11 as shown in FIG.

The ball screw nut member 25 is an annular member in which a spiral second ball screw groove 25a corresponding to the ball screw groove 23 is formed on the inner circumference, and a third screw groove in which the gear 28 meshes is formed on the outer peripheral surface. Has been done. The ball screw nut member 25 is rotatably assembled with respect to the axle 4 by interposing a rolling element (not shown) or the like between the second ball screw groove 25a and the ball screw groove 23. Further, one end side of the ball screw nut member 25 is attached to the inner ring of the bearing 26.

Further, as shown in FIG. 1, a second rolling groove 33 corresponding to a rolling groove 29 formed on the outer surface of the axle 4 is formed on the inner peripheral surface of the insertion hole into which the axle 4 of the hub member 16 is inserted. Is formed, and a plurality of rolling elements 32 are arranged between the rolling groove 29 and the second rolling groove 33.

In the rotary electric machine 10 according to the present embodiment configured as described above, when the drive motor 27 of the moving mechanism 20 is rotated to rotate the ball screw nut member 25 via the gear 28, the ball screw nut member 25 becomes the axle 4 Is formed in the ball and moves in the axial direction along the ball screw groove 23. Since the ball screw nut member 25 is assembled to the ball spline nut member 24 via the bearing 26, the moving base portion 30 is moved axially together with the stator 11.

As described above, in the rotary electric machine 10 according to the present embodiment, the ball screw nut member 25 is rotationally moved by the drive motor 27 of the moving mechanism 20, so that the stator 11 is inserted and removed from the rotor 12 in the axial direction. Since the stator 11 can be moved to the rotor 12, the output characteristics can be changed according to the relative position of the stator 11 with respect to the rotor 12.

As shown in FIG. 1, the rotor 12 has a back yoke 13 made of a conductive metal or the like, and a magnet 14 arranged so as to face the stator 11, and the back yoke 13 has a wheel 3. It is assembled to the wheel housing 15 attached to the wheel 3, and the wheel 3 rotates with the rotation of the rotor 12.

The rotary electric machine 10 according to the present embodiment has a stator 11 in which an armature coil 11b wound around a stator core 11a is arranged along the circumferential direction as shown in FIG. 2, and a stator 11 as shown in FIG. It is provided with a rotor 12 that is rotatably arranged with respect to a predetermined gap. As the winding method of the armature coil, various conventionally known winding methods can be adopted.

As shown in FIG. 3, the facing surfaces of the magnet 14 and the stator core 11a are formed in a stepped shape extending in the radial direction along the axial direction of the stator 11, for example, a three-step stepped shape. ing. By forming the facing surface between the magnet 14 and the stator core 11a in a stepped shape in this way, the gap between the magnet 14 and the stator core 11a is increased as the stator 11 moves by the moving mechanism described later. There is.

Further, a chamfered portion C is provided at the corner portion of the stepped shape of the magnet 14, and a space S larger than the gap is formed between the corner portion and the stator core 11a. The cross-sectional shape of this space S can be formed into a substantially triangular shape.

Further, it is preferable that the ratio of the radial length to the axial length of the cross-sectional shape of the space S is set to 1: 1 to 1: √3. By forming the space S between the staircase-shaped corners of the magnet 14 and the stator core 11a in this way, even when the corners face each other as the stator 11 moves, the corners face each other. It is possible to reduce the increase in suction force due to the approaching magnets.

Further, by forming the chamfered portion C at the corner portion of the stepped shape of the magnet 14, even if the corner portions face each other due to the movement of the stator 11, the corner portions are attracted by approaching each other. The increase in force can be reduced.

Further, the axial lengths L1 to L3 of each step in the staircase shape may be equally divided in the axial direction to have the same length, but it is preferable to form the lengths in the rotation axis direction so as to be different from each other. By setting the length of each stage in the rotation axis direction to a different length in this way, the timing at which the suction force increases with the movement of the stator 11 in the axial direction by the movement mechanism described later is dispersed, and the suction force is dispersed. It is possible to lower the maximum value of.

The shape of the surface of the stator core 11a facing the magnet 14 is not limited to the cross-sectional staircase shape, and may be formed in a tapered shape that is inclined with respect to the moving direction of the stator 11 as shown in FIG. ..

By forming the stator core 11a'in a tapered shape in this way, in the stepped stator core 11a, a loss due to eddy currents generated in a plurality of stepped portions of the staircase shape occurs when the stator 11 is pulled out. By doing so, the stepped portion can be formed only on the end surface of the stator core 11a', so that the loss due to the eddy current e can be reduced.

More specifically, as shown in FIG. 5, when the stator 11 is most inserted into the rotor 12, the facing area between the stator 11 and the rotor 12 is the largest, and the stator 11 and the rotor 12 have the largest facing area. Since the gap between the 12 is also the smallest, the output characteristics of the rotary electric machine 10 are high torque and low rotation. In such a state, the output characteristics are most suitable when a high torque is required although the speed is slow, such as when the vehicle starts.

Further, in this state, since the counter electromotive force increases, the power supply to the armature coil 11b is stopped, and during deceleration for braking the wheel 1, the counter electromotive force increases, so that power can be generated efficiently. It can act as a highly efficient regenerative brake.

When the drive motor 27 is rotated to apply a rotational force to the ball screw nut member 25, the ball screw nut member 25 rotates along the ball screw groove 23 of the axle 4 as the ball screw nut member 25 rotates. Move in the direction.

Here, in the state where the stator 11 is pulled out with respect to the rotor 12 and the corners of the staircase shape are closest to each other in the middle of FIG. 5, the suction force is most increased, but the pull-out amount is 2. .Since the inclination between 5 and 5 (mm) is small and the peak of attractive force is also small as compared with the comparative example, a chamfered portion C is provided at the corner of the magnet 14, and the corner and the stator core are provided. It can be confirmed that the suction force is suppressed by forming the space S between the 11a.

When the moving mechanism 20 is driven, the stator 11 is most extracted from the rotor 12, the facing area between the stator 11 and the rotor 12 is the smallest, and the gap between the stator 11 and the rotor 12 is large. It will be in the largest state. In this state, the counter electromotive force decreases, and the output characteristics of the rotary electric machine 10 become low torque and high rotation. In the state where the stator 11 is most extracted from the rotor 12 in this way, the output characteristics are most suitable for high-speed traveling which does not require torque.

On the other hand, when the corners of the stator core 111 and the magnet 114 are formed so as to face each other as the stator core 111 moves as in the comparative example shown in FIG. 6, the stator core 111 is inserted and removed as shown in FIG. When doing so, the suction force increases further when the corners are closest to each other and face each other.

Since the rotary electric machine 10 according to the present embodiment is rotationally held with respect to the axle 4 by hub members 16 arranged at both ends in the axial direction of the wheel housing 15, the rotary electric machine 10 can be reduced in size by reducing the size of the hub member 16. It is possible to reduce the weight, and it is possible to improve the response performance by shortening the arrival time to the required number of revolutions with the weight reduction.

Further, since the rotating shaft and the driving shaft are arranged coaxially, it is possible to reduce the size of the rotating electric machine 10. Further, the rotary electric machine 10 according to the present embodiment has a deceleration effect due to the ball screw nut member 25 and the ball screw groove 23 formed on the outer surface of the axle 4, so that the output of the drive motor 27 can be reduced. By downsizing the drive motor 27, the rotary electric machine 10 can be further downsized.

Further, since the moving mechanism 20 moves the stator 11 by the ball screw nut member 25 and the ball spline nut member 24, it is possible to control the movement of the stator 11 with good responsiveness and high energy efficiency. Become. Further, since the amount of movement by the moving mechanism 20 is controlled by the amount of rotation of the ball screw nut member 25, the most suitable output characteristic can be obtained by arbitrarily setting the position of the stator 11 according to the required output characteristic. It is possible to drive the rotary electric machine 10 with.

In the above-described embodiment, the case where the axle 4, the ball spline nut member 24, and the ball screw nut member 25 are assembled via the rolling element has been described, but these members do not pass through the rolling element. You may assemble them so that they slide against each other. Further, in the rotary electric machine 10 according to the present embodiment described above, the case where the rotary electric machine 10 according to the present embodiment is applied to the wheel 1 of an automobile has been described, but the application is not limited to the automobile, for example, wind power. It may be applied to a generator or a press processing machine. It is clear from the description of the claims that the form with such changes or improvements may be included in the technical scope of the present invention.

4 axles, 10 rotors, 11 stators, 11a, 11a'stator cores, 12 rotors, 14 magnets, 20 moving mechanisms, C chamfers, S space.

Claims (5)

A rotary electric machine having a stator having a stator core around which an armature coil is wound, and a rotor having a magnet that is rotatably arranged with respect to the stator through a predetermined gap and has a magnet facing the stator. In
The stator is attached to a moving mechanism that can move in the direction of the axis of rotation.
Of the facing surfaces of the magnet and the stator core, at least the facing surface of the magnet is formed in a cross-sectional stepped shape extending in the radial direction along the moving direction of the stator.
A rotary electric machine characterized in that a space larger than the gap is formed between the corner portion of the magnet and the stator core. In the rotary electric machine according to claim 1,
A rotary electric machine characterized in that the length in the direction of the rotation axis in each step of the staircase shape is different. In the rotary electric machine according to claim 1 or 2.
The space is a rotary electric machine characterized in that the ratio of the radial length to the axial length is 1: 1 to 1: √3. In the rotary electric machine according to any one of claims 1 to 3,
The facing surface of the stator core is formed in a stepped cross section extending in the radial direction along the moving direction of the stator or a tapered cross section inclined with respect to the moving direction of the stator. Electric. An in-wheel motor using the rotary electric machine according to any one of claims 1 to 4.

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