Rotating electric machine

Abstract

Provided is a rotary electric machine having a variable flux mechanism in which a stator and a rotor can move relative to each other, the rotary electric machine being thin and small in diameter, and a cooling passage being easily arranged. The rotating electrical machine includes: a rotating shaft; a rotor which has a permanent magnet, applies a rotational force to the rotating shaft, and is assembled so as to be axially movable with respect to the rotating shaft; a moving mechanism that moves the rotor in the axial direction; a stator that is disposed so as to have a gap in the radial direction from the outer periphery of the rotor, and that has a coil; and a rotation prevention mechanism that prevents rotation of the movement mechanism, the movement mechanism having: a screw shaft member that rotates together with the rotor, has a helical thread groove formed on the outer peripheral surface thereof, and has the rotation shaft passed through the inner peripheral surface thereof; and a screw nut member screwed into the screw groove of the screw shaft member, the rotation prevention mechanism having: a guide part formed on the screw shaft member; and a sliding part provided in the housing.

Description

Technical Field

[0001] This invention relates to rotary electric motors, and more particularly to rotary electric motors used as in-wheel motors incorporated in the wheels of motor vehicles. Background Technology

[0002] In recent years, it has become known that rotary motors can obtain output characteristics corresponding to the rotational speed by adjusting the output at low and high speeds. Various structures are known for such rotary motors, such as the following rotary motor having a stator, a rotor that is coaxially arranged and rotatable relative to the stator, and a moving mechanism that changes the relative position of the stator with respect to the rotor in the axial direction, wherein an armature coil and an iron core are provided in the stator, and a magnet is provided in a manner opposing the iron core.

[0003] According to such a rotary motor, when rotating at low speed, the stator is moved axially by increasing the opposing area of ​​the stator and rotor using a moving mechanism, thereby increasing the effective magnetic flux through the stator and achieving high torque. When rotating at high speed, the stator is moved by decreasing the opposing area of ​​the stator and rotor, thereby decreasing the effective magnetic flux through the stator and achieving high-speed rotation.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2008-141900 Summary of the Invention

[0007] The problem that the invention aims to solve

[0008] However, based on conventional rotary motors, when using rotary motors as in-wheel motors, a thin and small-diameter structure is sought, considering the impact of increased unsprung mass on ride comfort and the reduction in accommodation space caused by the suspension geometry being offset inwards by compressing the chassis space.

[0009] Traditional rotary motors have mechanisms for axially moving the stator around the rotation axis, which makes it difficult to reduce the diameter of the rotary motor itself.

[0010] Furthermore, if the relative movement between the stator and rotor is set such that the stator, which is located inside the rotor, moves axially as in conventional rotary motors, then when the stator coils need to be cooled, the passage for the cooling refrigerant needs to be set in the axially moving stator, which presents a problem of difficulty in constructing such a passage.

[0011] The present invention was made to solve the above-mentioned problems, and its purpose is to provide a rotary motor having a variable flux mechanism in which the stator and rotor can move relative to each other, which enables the rotary motor to be thin and small in diameter, and can be easily configured with cooling passages.

[0012] Methods for solving problems

[0013] The rotary electric motor of the present invention, which solves the above-mentioned problems, is characterized in that it comprises: a rotating shaft; a rotor having a permanent magnet, imparting a rotational force to the rotating shaft, and assembled in a manner capable of axial movement relative to the rotating shaft; a moving mechanism that moves the rotor axially; a stator configured to have a radial clearance with the outer periphery of the rotor, and having coils; and a rotation prevention mechanism that prevents rotation of the moving mechanism, the moving mechanism comprising: a lead screw member that rotates with the rotor and has a helical threaded groove formed on its outer peripheral surface, and an inner peripheral surface through which the rotating shaft passes; and a lead screw nut member that engages with the threaded groove of the lead screw member; the rotation prevention mechanism comprising: a guide portion formed on the lead screw member; and a sliding portion disposed in the housing.

[0014] Invention Effects

[0015] The rotary motor according to the present invention comprises: a stator configured with a radial clearance from the outer periphery of the rotor and having coils; and a rotation prevention mechanism that prevents rotation of a moving mechanism, the moving mechanism comprising: a lead screw member that rotates with the rotor and has a helical threaded groove formed on its outer peripheral surface and through which a rotating shaft passes; and a lead screw nut member that engages with the threaded groove of the lead screw member; the rotation prevention mechanism comprising: a guide portion formed on the lead screw member; and a sliding portion disposed in the housing, thereby enabling the prevention of rotation of the lead screw member while guiding its axial movement, thus enabling the construction of a thin and small-diameter rotary motor.

[0016] Furthermore, in the rotary motor according to the present invention, the variable flux mechanism is arranged in a so-called inner rotor type rotary motor having a stator with a radial gap from the outer periphery of the rotor and having coils. Therefore, even when the stator needs to be cooled, since the stator does not move axially, a cooling passage can be easily formed. Attached Figure Description

[0017] Figure 1 This is a diagram showing the rotary motor of an embodiment of the present invention used in an in-wheel motor.

[0018] Figure 2 This is a front view of a rotary electric motor according to an embodiment of the present invention.

[0019] Figure 3 yes Figure 2 AA section view in the image.

[0020] Figure 4 yes Figure 3 Enlarged view of part B in the image.

[0021] Figure 5 This is a perspective view illustrating the rotation prevention mechanism of a rotary electric motor according to an embodiment of the present invention.

[0022] Figure 6 This is a cross-sectional view illustrating the operation of the variable flux mechanism of the rotary electric machine according to an embodiment of the present invention. Detailed Implementation

[0023] The embodiments of the rotary electric motor of the present invention will now be described with reference to the accompanying drawings. It should be noted that the following embodiments do not limit the invention involved in each technical solution, and the combinations of features described in the embodiments are not all necessary for the solution of the invention.

[0024] Figure 1 This is a diagram illustrating the use of the rotary motor according to an embodiment of the present invention in an in-wheel motor. Figure 2 This is a front view of a rotary electric motor according to an embodiment of the present invention. Figure 3 yes Figure 2 AA section view, Figure 4 yes Figure 3 Enlarged view of part B in the image. Figure 5 This is a perspective view illustrating the rotation prevention mechanism of a rotary electric motor according to an embodiment of the present invention. Figure 6 This is a cross-sectional view illustrating the operation of the variable flux mechanism of the rotary electric machine according to an embodiment of the present invention.

[0025] like Figure 1 As shown, the rotary motor 10 of this embodiment is preferably used as a so-called in-wheel motor assembled on a wheel 1 of a motor vehicle or the like. The wheel 1 has a tire 3 assembled on a rim (not shown), and the rotary motor 10 is built into the rim. In addition, a brake disc 2 is mounted on the rotation shaft 31 of the rotary motor 10.

[0026] like Figure 2 as well as Figure 3 As shown, the rotary motor 10 includes a housing 40 that houses a stator 20 and a rotor 30 that is rotatable relative to the stator 20. The stator 20 is configured to have a radial clearance with the outer periphery of the rotor 30. The rotor 30 includes a rotating shaft 31 and bolts 32 that rotate together with the rotating shaft 31. A wheel rim (not shown) of the wheel 1 is mounted to the bolts 32.

[0027] In the stator 20, armature coils, formed by winding wires onto a stator core (not shown), are arranged circumferentially. The rotor 30 includes: a rotor body 34, which is assembled to the moving mechanism 50; and a rotor core 33, which is circumferentially opposite the rotor body 34 and the stator 20. In the rotor core 33, a plurality of permanent magnets (not shown) are arranged circumferentially. Additionally, a cooling mechanism (not shown) is provided in the stator 20 for cooling.

[0028] like Figure 4 as well as Figure 5 As shown, the moving mechanism 50 includes: a spline nut member 53, which is movably mounted on a spline groove 31a formed along the axial direction of the rotating shaft 31; a lead screw member 51, which is mounted on the outer periphery of the spline nut member 53 via a bearing 56; and a lead screw nut member 52, which is rotatably mounted on the lead screw member 51.

[0029] The rotating shaft 31 is a component that rotates around the axis together with the rotor 30, and is supported by a rotating bearing 57 mounted on the housing 40 to enable it to rotate.

[0030] The lead screw shaft member 51 has a helical threaded groove formed on its outer peripheral surface, and a hollow shape formed in its central part to allow the bearing 56, spline nut member 53, and rotating shaft 31 to pass through. The lead screw shaft member 51 has a guide portion 59 extending axially. Furthermore, the lead screw nut member 52 is configured to be divided into multiple parts (e.g., two) axially. It should be noted that the lead screw nut member 52 may also be formed as a single piece without axial division.

[0031] Preferably, a pair of guide portions 59 are formed along the horizontal direction. The guide portions 59 are guided as cam followers 58 mounted on the sliding portion of the housing 40 to form a rotation prevention mechanism.

[0032] The lead screw nut component 52 has a nut-side threaded groove formed on its inner circumferential surface, corresponding to the threaded groove, and rolling elements 54 are arranged spirally between the threaded groove and the nut-side threaded groove. In addition, a gear portion 52a that meshes with the drive motor 60 is installed at the end of the lead screw nut component 52.

[0033] The spline nut component 53 is a cylindrical component with a nut-side spline groove corresponding to the spline groove 31a, and a rotor body 34 is assembled on its outer circumferential surface. A plurality of rolling elements 55 are arranged axially between the spline groove 31a and the nut-side spline groove.

[0034] The cam follower 58 is a shaft bearing, comprising: a shaft fixed to the housing 40; and a bearing assembled to rotate freely about the shaft. The outer peripheral surface of the bearing abuts against the upper surface of the aforementioned guide portion 59, and guides the axial movement of the lead screw shaft member 51 by means of the guide portion 59. It should be noted that the guide portions 59 are preferably formed in a pair in a horizontal direction relative to the ground. By such a horizontal arrangement, the guide portions 59 and the cam follower 58 can be used to properly absorb the impact when the vehicle is impacted from the ground.

[0035] Next, the operation of the rotary motor 10 in this embodiment will be explained. Figure 3 In this state, when current is supplied to the coil of stator 20, rotor 30 rotates relative to stator 20 under the interaction with the magnetic field based on the permanent magnets disposed in rotor 30.

[0036] In this configuration, with the rotor 30 inserted to its deepest point relative to the stator 20, the opposing area between the stator 20 and the rotor 30 is maximized, and the output characteristics of the rotary motor 10 become high torque / low rotation type. This configuration is the most suitable for output characteristics under conditions of slow speed but high torque requirement, such as when a motor vehicle is starting.

[0037] Furthermore, in this state, the power supply to the stator 20 stops due to the increase in back electromotive force, and the generator can generate electricity efficiently when the wheel 1 is braked and decelerated, thus functioning as a highly efficient regenerative brake.

[0038] Next, the operation of the moving mechanism 50 will be explained. The rotor body 34 is mounted on the spline nut member 53, so the rotation of the rotor body 34 is transmitted to the rotating shaft 31 via the spline nut member 53 and the spline groove 31a. In addition, a bearing 56 is sandwiched between the spline nut member 53 and the lead screw member 51, so the rotation of the rotor 30 is not transmitted to the lead screw member 51, but is interrupted by the bearing 56.

[0039] By driving the drive motor 60, the gear portion 52a mounted on the lead screw nut component 52 is rotated, thereby causing the lead screw shaft component 51 to move axially. At this time, since the spline nut component 53 and the rotating shaft 31 are assembled by means of the spline groove 31a, the spline nut component 53 moves axially together with the rotor body 34.

[0040] At this time, through such Figure 6As shown, the rotor 30 is axially withdrawn relative to the stator 20, thus minimizing the opposing area between the rotor core 33 of the rotor 30 and the stator 20. In this state, the back electromotive force is reduced, and the output characteristics of the rotary motor 10 become low torque / high rotation type. This state of withdrawing the rotor 30 relative to the stator 20 is the most suitable state for output characteristics when high-speed operation does not require torque.

[0041] It should be noted that the moving mechanism 50 enables the rotor 30 to move infinitely in the axial direction. Therefore, by controlling the rotation of the drive motor 60, the position of the rotor 30 can be adjusted to a position corresponding to the desired output characteristics.

[0042] The rotary motor 10 of this embodiment, configured in this way, is a rotary motor having a variable flux mechanism based on a moving mechanism 50. The hollow lead screw member 51, which slides axially along the rotation shaft 31, is provided with a guide portion 59 extending axially. This guide portion 59 is guided by a sliding portion based on a cam follower 58. Thus, while guiding the sliding of the hollow lead screw member 51, the cam follower 58 guides the two guide portions 59 from above, thereby forming a variable flux mechanism that prevents rotation of the lead screw member 51 with the guide portions 59. In this case, the cam follower 58 guides the respective guide portions 59 from the same direction (above), thereby more effectively preventing rotation of the lead screw member 51 by suppressing both forward and reverse rotation around the axis. It should be noted that the direction in which the cam follower 58 guides the guide portions 59 is not limited to above; it can also be from below, etc., with the cam follower 58 guiding a pair of guide portions 59 from the same direction.

[0043] Furthermore, regarding the isolation of vehicle load in the rotary motor 10 of this embodiment, the driving torque and braking torque are isolated by using the bearing 56 sandwiched between the spline nut member 53 and the lead screw member 51, and the axial impact load is isolated by using the spline nut member 53. This allows for the miniaturization of the components of the moving mechanism 50 that allows the magnetic flux to be variable, and also suppresses damage to the rotor core.

[0044] Furthermore, since the components of the moving mechanism 50 can be arranged axially, the radial dimension of the rotary motor 10 can be prevented from becoming excessive. Moreover, by using the lead screw and nut member 52 in the moving mechanism 50 and the cam follower 58 in the sliding part, further miniaturization can be achieved.

[0045] Furthermore, the cam follower 58 and guide 59, as well as the rotating shaft 31 and spline nut member 53, which are sliding parts, employ rolling guidance by means of rolling elements, so that the resistance can be set to be small, thereby preventing the drive motor 60 from becoming bulky and deteriorating over time.

[0046] In addition, the rotary motor 10 of this embodiment has a variable flux mechanism that fixes the stator 20 that needs to be cooled and moves the rotor 30 in the axial direction, so that the cooling passage can be easily configured.

[0047] The rotary motor 10 of this embodiment described above illustrates the case where rolling elements 54 and 55 are sandwiched between the lead screw shaft member 51 and the lead screw nut member 52, and between the spline groove 31a and the spline nut member 53, and the case where rolling guidance is applied to guide the guide portion 59 by means of a cam follower 58. However, these can also be configured as sliding guidance where the members directly slide into contact with each other without the presence of rolling elements. Furthermore, the case where a pair of guide portions 59 are formed in the horizontal direction has been described, but the number of guide portions 59 can be two or more, for example, multiple guide portions 59 can be formed at equal intervals in the circumferential direction of the lead screw shaft member 51. Moreover, the case where a pair (two) of guide portions 59 are formed on the lead screw shaft member 51 has been described, but two or more guide portions 59 can also be formed on the lead screw shaft member 51. In this case, it is preferable that the cam follower 58 guides at least two of the guide portions 59 from the same direction. In this case, the two guide portions 59 are preferably arranged symmetrically about their respective axes. As can be seen from the description of the technical solution, any modifications or improvements made in this way are also included within the technical scope of this invention.

[0048] Explanation of reference numerals in the attached figures

[0049] 3 Tire; 10 Rotary motor; 20 Stator; 30 Rotor; 31 Rotating shaft; 31a Spline groove; 40 Housing; 50 Moving mechanism; 51 Lead screw shaft assembly; 52 Lead screw nut assembly; 52a Gear; 53 Spline nut assembly; 58 Cam follower; 59 Guide; 60 Drive motor.

Claims

1. A rotary electric motor, characterized in that, The rotary motor has: Rotation axis; The rotor has permanent magnets that impart rotational force to the rotating shaft and is assembled in a manner that allows it to move axially relative to the rotating shaft; A moving mechanism that moves the rotor axially; A stator, which is configured with a radial gap from the outer periphery of the rotor, and has coils; and A rotation prevention mechanism prevents the movement mechanism from rotating. The moving mechanism includes: a lead screw shaft member that rotates together with the rotor and has a helical threaded groove formed on its outer circumferential surface, and an inner circumferential surface through which the rotating shaft passes; and a lead screw nut member that engages with the threaded groove of the lead screw shaft member. The rotation prevention mechanism has: a guide portion formed on the lead screw member; and a sliding portion disposed in the housing.

2. The rotary motor according to claim 1, characterized in that, A spline groove extending axially is formed on the outer periphery of the rotating shaft. The rotor has a spline nut component that engages with the spline groove.

3. The rotary motor according to claim 2, characterized in that, The spline nut component can be inserted into the inner circumference of the lead screw component.

4. The rotary motor according to claim 1, characterized in that, The moving mechanism has a drive motor that imparts rotational force to the lead screw and nut assembly.

5. The rotary motor according to claim 4, characterized in that, The lead screw nut component has teeth formed on its outer periphery that mesh with the drive motor.

6. The rotary motor according to claim 1, characterized in that, A tire is disposed on the outer periphery of the stator, the tire is mounted on a rim, and the rim is mounted to rotate together with the rotor.

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