JP6376987B2 - Rotating electric machine - Google Patents

Description

  The present invention relates to a rotating electrical machine, and more particularly to a mounting structure for a rotation angle sensor of the rotating electrical machine.

  In the synchronous motor, since it is necessary to control the current flowing through the stator winding based on the rotation position of the rotor, a rotation angle sensor that detects the magnetic pole position of the rotor is provided. Some rotation angle sensors use magnetoresistive elements. This is to detect the direction of the magnetic field, and a sensor magnet having a magnetic field formed in the radial direction of the rotor is attached to the end of the rotating shaft, and a rotation angle sensor is attached so as to face it. This type of sensor is generally used from the viewpoint that durability and stability are not impaired even if foreign matter enters.

  For example, in Patent Document 1, a sensor magnet is fixed to one end of a rotating shaft, and a magnetic sensor is provided so as to face the sensor magnet in the axial direction. This magnetic sensor is a magnetoresistive element that is sensitive to a magnetic field parallel to the magnetosensitive surface, and outputs a signal corresponding to the magnitude of the internal resistance that changes with the rotation of the sensor magnet to the control board. The rotational position of the rotating shaft, that is, the magnetic pole position of the rotor is obtained based on the signal input from the magnetic sensor, and the result is output to the drive control device (see Patent Document 1).

JP 2014-109773 A

A permanent magnet constituting the field part of the rotating electrical machine is fixed to the rotor core, and this rotor core is fixed to the rotating shaft. On the other hand, the sensor magnet is fixed to the rear end of the rotation shaft, and the rotation angle sensor is arranged to face the sensor magnet. As described above, a plurality of members are interposed between the permanent magnet forming the field part and the sensor magnet. For this reason, there is a problem in that it is difficult to align the rotor magnets with the sensor magnets with high accuracy due to the accumulation of dimensional errors between the members.
The present invention has been made to solve the above-described problems. By positioning and fixing the sensor magnet directly to the rotor core, the positional deviation between the rotor core and the sensor magnet is minimized. For the purpose.

A rotating electrical machine according to the present invention includes a rotor and a stator disposed on an outer peripheral side of the rotor, the stator includes a stator core and a stator winding, and the rotor includes a rotor core and It has a permanent magnet fixed to the outer peripheral surface of this rotor core, and a rotation shaft is inserted into the center of the rotor core,
The rotating shaft is configured to protrude only from one axial end surface of the rotor core, and the sensor magnet is an end surface of the rotor core whose rotating shaft does not protrude with respect to the rotor core, and the center of the rotor core. directly fixed to the position Rutotomoni, the sensor magnet rotor core and the sensor magnet is disposed so as to have a predetermined phase with respect to the rotational direction of the rotor core, the rotational angle sensor and the void in the axial direction relative to the sensor magnet It is arranged via.

  According to the rotating electric machine configured as described above, since the sensor magnet can be directly attached to the rotor core, the magnetic field magnetic pole and the sensor magnet can be aligned with high accuracy and easily.

1 is a side cross-sectional view showing a rotating electrical machine according to Embodiment 1. FIG. FIG. 3 is a plan sectional view showing the rotating electrical machine according to the first embodiment. 1 is a side cross-sectional view showing a rotating electrical machine according to Embodiment 1. FIG. It is a perspective view which shows the relationship between a sensor magnet and a rotation angle sensor. 1 is a side cross-sectional view showing a rotating electrical machine according to Embodiment 1. FIG. 5 is a side cross-sectional view showing a rotating electrical machine according to Embodiment 2. FIG. 6 is a side cross-sectional view showing a rotating electrical machine according to Embodiment 3. FIG.

Embodiment 1 FIG.
FIG. 1 is a side sectional view showing the rotating electrical machine according to the first embodiment. In this embodiment, the sensor magnet is directly fixed to the rotor core to reduce the mounting error of the sensor magnet. The rotating electrical machine 1 is a brushless motor and has three or more phases. The frame 2, the stator 3, the rotor 4, the rotating shaft 5, the bearing holder 6, the bearing 7, the bearing 8, and the sensor magnet 9 The current control device 10 and the rotation angle sensor 11 are provided. The rotating electrical machine according to the present embodiment is an integrated rotating electrical machine in which the current control device 10 is integrated on the rear side of the motor unit 12. In the axial direction of the rotating electrical machine, the output end side 5a of the rotating shaft 5 is defined as the front side, and the opposite side is defined as the rear side. FIG. 2 is a plan sectional view showing a case where the motor unit 12 including the stator and the rotor is cut in a direction perpendicular to the axis.

  The stator 3 constitutes an armature portion of the rotating electrical machine, and is disposed on the outer peripheral side of the rotor 4 via a certain gap, and includes a stator core 13 and a stator winding 14. The stator core 13 has a substantially cylindrical shape and is configured by laminating thin plates in the axial direction. The stator core 13 is composed of an annular back yoke 15 and a plurality of radially extending tooth portions 16. The stator winding 14 is wound around a slot portion 17 provided between the tooth portions 16. ing. The stator core 13 is fixed by press fitting or the like in a cylindrical frame 2 made of a metal such as aluminum or iron.

  The rotor 4 constitutes a field part of a rotating electric machine, and an even number of permanent magnets 19 are fixed at an equal pitch on the outer peripheral surface of a rotor core 18 whose outer shape is substantially cylindrical. One of the magnetic poles of the permanent magnet 19 is arranged inside the rotor 4 and the other is arranged outside, and the polarity is reversed between the adjacent permanent magnets 19. The rotor core 18 is made of a ferromagnetic material, and is integrally formed by laminating thin plates or by forging or cutting. The center of the rotor core 18 is hollow, the rear end portion has a small diameter, and the rotary shaft 5 is press-fitted and fixed to the small diameter portion.

  The rotating shaft 5 is held in a rotatable state by a bearing holder 6 via a bearing 7 and a bearing 8. The bearing holder 6 is made of a metal such as aluminum or iron, and is formed in a cylindrical shape from an annular portion on the front side toward the rear side. A bearing 7 and a bearing 8 for rotatably holding the rotary shaft 5 are arranged inside the cylindrical portion of the bearing holder 6. Since the bearings 7 and 8 are fitted into the bearing holder 6 from the front side, the outer diameter of the bearing 8 disposed on the rear side is smaller than that of the bearing 7 disposed on the front side.

  Further, since the rotor core 18 is press-fitted into the rear end after passing the bearing 8 from the front side to the rotary shaft 5, the inner diameter of the bearing 8 is larger than the diameter of the press-fitted portion between the rotor core 18 and the rotary shaft 5. It is getting bigger. In the rotor core 18, only the vicinity of the permanent magnet 19 disposed on the outer periphery is a magnetically necessary portion, and the central portion is not a magnetic flux path. Therefore, the rotor iron core 18 is provided with a hollow portion 18a, the bearing holder 6 is disposed therein, and the rotor iron core 18 and the bearing holder 6 are overlapped in the axial direction so that the length of the entire rotating electrical machine in the axial direction is increased. It is shortened. The rotating shaft 5 is configured to protrude only from one end surface (front side end surface) in the axial direction of the rotor core 18, and is configured not to protrude from the other end surface (rear side end surface).

  In FIG. 1, the bearing holder 6 and the frame 2 are separate parts, and a fitting portion 28 is provided between them to ensure coaxiality. The bearing holder 6 and the frame 2 are fixed to each other in the axial direction by screws 20 provided on the outer peripheral portion. Although FIG. 1 shows the case of fixing with screws, it may be fixed by other methods such as adhesion, press fitting, and welding. FIG. 3 is a side sectional view showing a rotating electrical machine according to another embodiment. In FIG. 3, the bearing holder and the frame are constituted by an integral part 61.

  FIG. 4 is a perspective view showing the relationship between the sensor magnet 9 and the rotation angle sensor 11. A magnetoresistive effect element (GMR element) has a structure in which a nonmagnetic thin film is sandwiched between two magnetic thin films, and the resistance value of the nonmagnetic thin film decreases when the magnetization directions of the two magnetic thin films are parallel. . Conversely, when the magnetization directions of the two magnetic thin films are not parallel, the resistance value is large. When such a magnetoresistive effect element is applied to the rotation angle sensor 11, the direction of magnetization is fixed in one direction in one of the two magnetic thin films, and the other follows the external magnetic field and is magnetized. The direction is changing. Then, the resistance value changes due to the change in the direction of the external magnetic field, and the direction of the external magnetic field is obtained using this to detect the rotation angle. The rotation angle sensor 11 is packaged as shown in FIG. 4, and a sensor magnet 9 is arranged at a predetermined distance from the surface thereof. The magnetization direction of the sensor magnet 9 is set in a plane parallel to the rotation angle sensor 11, and when the sensor magnet 9 rotates, the rotation angle is detected by the magnetoresistive effect described above. In addition to the above, there are Hall elements, tunnel magnetoresistive elements (TMR elements), etc. as the elements of the rotation angle sensor, and the detection principles are different, but the change in the magnetization direction of the sensor magnet 9 is detected with the GMR element. Further, the positional relationship between the rotation angle sensor and the sensor magnet is the same as that of the GMR element.

  A sensor magnet 9 is fixed to the rear side end face of the rotor core 18. That is, the sensor magnet 9 is directly fixed to the rear side end face, which is one end face where the rotating shaft 5 does not protrude from the rotor core 18. FIG. 1 shows an example in which adhesion is used as a fixing method of both. On the other hand, as shown in FIG. 5, the pressing member 21 may be fixed to the rotor core 18 and the sensor magnet 9 may be pressed and fixed. In any fixing method, the sensor magnet 9 is positioned at the center of the rotor core 18 and the rotor core 18 and the sensor magnet 9 are in a predetermined phase with respect to the rotation direction of the rotor core 18. Positioning means is provided between the two. That is, the permanent magnet 19 is attached to the outer peripheral surface of the rotor core 18, and magnetic poles are alternately arranged in the circumferential direction from N → S → N → S. It is the role of the rotation angle sensor 11 to grasp the angle of the magnetic pole, but when the space for arranging the rotation angle sensor 11 is narrow, the direction of the magnetic pole of the permanent magnet 19 attached to the outer peripheral surface of the rotor is directly measured by the rotation angle sensor. 11 is difficult to measure. Therefore, a sensor magnet 9 is attached to the rotor 4, and the magnetic pole direction of the sensor magnet 9 is detected by the rotation angle sensor 11 to obtain the magnetic pole direction of the rotor. For this reason, the positioning of the sensor magnet 9 with respect to the magnetic pole direction of the rotor 4 is important. Positioning is roughly divided into two elements, one is positioning between the center of the sensor magnet 9 and the axis of the rotor 4, and the other is phase alignment of the rotation direction of the sensor magnet 9 with respect to the rotor magnetic pole direction. It is. In this embodiment, these positionings can be performed accurately.

  The rotation angle sensor 11 detects the magnetic pole direction of the sensor magnet 9 and is arranged to face the sensor magnet 9 with a predetermined gap in the rotation axis direction. The rotation angle sensor 11 is fixed to the sensor substrate 22. The sensor substrate 22 is disposed so as to be orthogonal to the axial direction of the rotating electrical machine, and is fixed to the current control device 10 so that the rotation angle sensor 11 is located on the front side of the sensor substrate 22. The rotation angle sensor 11 detects the direction of the magnetic poles of the sensor magnets 9 arranged to face each other, and outputs the rotation position of the rotor 4, that is, the magnetic pole position of the rotor 4. The current control device 10 controls the current flowing through the stator winding 14 using the magnetic pole position, and generates a rotating magnetic field. The rotor 4 rotates corresponding to the rotating magnetic field.

  In the conventional structure, the rotor core is fixed to the rotating shaft, and the sensor magnet is fixed to the rear side end of the rotating shaft. Therefore, there are two fixed portions between the rotor core and the rotation shaft and between the rotation shaft and the sensor magnet. On the other hand, in the structure according to the present embodiment, since the sensor magnet 9 can be directly positioned and fixed to the rotor core 18, the positional deviation between the rotor core 18 and the sensor magnet 9 can be minimized. . As a result, the rotor magnetic pole detection accuracy in the rotation angle sensor 11 is improved. In driving the rotating electrical machine, it is necessary to accurately detect the rotation angle of the rotor 4 in order to realize highly accurate current control. As a result, it is possible to improve the characteristics of the rotating electrical machine, such as improving torque and reducing torque ripple.

Embodiment 2. FIG.
FIG. 6 is a side sectional view showing a rotating electrical machine according to the second embodiment. In the present embodiment, the rotation angle sensor 11 is directly fixed to the control board 23 that is a component of the current control device 10. An arithmetic device 24 for operating the current control device 10 using an angle signal output from the rotation angle sensor 11 is mounted on the control board 23, and the arithmetic device 24 is rotated by a signal wiring incorporated in the control board 23. It is electrically connected to the angle sensor 11. Although FIG. 6 shows a case where the arithmetic unit 24 is arranged on the rear side of the control board 23, it may be arranged on the front side.

  When the rotating electrical machine is driven, the current flowing through the stator winding 14 is sequentially switched according to the magnetic pole position of the rotor 4. A large current needs to flow through the stator winding 14, and electromagnetic noise is generated when the current is switched. If electromagnetic noise is superimposed on the angle signal input from the rotation angle sensor 11 to the arithmetic unit 24, an error occurs in the angle signal, and high-precision current control cannot be performed. Therefore, in the present embodiment, by shortening the electrical wiring from the rotation angle sensor 11 to the arithmetic device 24, it is possible to suppress the superimposition of electromagnetic noise and to reduce the angle signal error.

Embodiment 3 FIG.
FIG. 7 is a side sectional view showing a rotating electrical machine according to the third embodiment. The current control device 10 includes a control unit and a power unit. In the control unit, an arithmetic device 24 that calculates an energization pattern to the stator winding 14 based on the angle information of the rotor 4 obtained by the rotational angle sensor 11, and a control board 23 on which the arithmetic device 24 is mounted. Consists of The power section is composed of a power transistor 25 that switches energization to the stator winding 14 in accordance with the energization pattern. In the power section, the power transistor 25 generates heat in order to switch a large current to the stator winding 14. For this reason, the power section is provided with a heat sink 26 made of a metal material having good thermal conductivity such as aluminum, and the heat generated in the power transistor 25 is released to the outside air.

  The bottom surface (the top surface in the figure) of the power transistor 25 is in contact with the heat sink 26 directly or via grease. When the power transistor 25 generates heat, the temperature of the heat sink 26 rises due to heat conduction. Since the outside of the heat sink 26 is exposed to the outside air, heat is radiated from the heat sink 26 to the outside air, and the heat generated in the power transistor 25 is finally radiated to the outside air. In the current control device 10, the components are arranged in the order of the control unit including the rotation angle sensor 11 and the power unit from the front side in the axial direction. In the power section, the power transistor 25 is disposed on the front side, and the heat sink 26 is disposed on the rear side.

  Since the power section switches the current flowing through the stator winding 14, a wiring 27 connecting the power section and the stator winding 14 is necessary. The wiring 27 is disposed on the outermost periphery in the current control device 10 and connects the power unit and the stator winding 14 by passing through the outer periphery of the control unit.

  A large current needs to flow through the stator winding 14, and the current is switched by the power transistor 25 to switch the energization current. However, when a large current is switched, electromagnetic noise is generated when switching the current in the power section. . To reduce the effect of electromagnetic noise, for example, connect a capacitor to reduce the electromagnetic noise, place an electromagnetic shield to shield the electromagnetic noise, and process the angle detection result with software according to the switching timing. There are methods such as canceling the influence of noise and increasing the distance from the electromagnetic noise source to the rotation angle sensor 11. Of the above measures, capacitors are generally mounted, but they are not sufficient as a measure against electromagnetic noise. Therefore, in the present embodiment, the distance from the rotation angle sensor 11 or a signal line connecting the rotation angle sensor 11 and the arithmetic unit 24 to the power unit that is the source of electromagnetic noise is increased.

  The components of the current control device 10 are roughly divided into a power unit including the power transistor 25, a rotation angle sensor 11 unit, and a control board 23 unit for performing arithmetic processing. When the motor is shortened by reducing the axial length of the motor, the motors are arranged close to each other. Even in such a case, the distance between the rotation angle sensor 11 and the power unit that is an electromagnetic noise generation source can be increased by arranging each unit from the motor unit 12 side with the rotation angle sensor 11, the control board 23, and the power unit. Can do.

In the present embodiment, since the distance from the rotation angle sensor 11 or the signal line connecting the rotation angle sensor 11 and the arithmetic unit 24 to the power unit that is the source of noise can be separated, electromagnetic noise to the angle signal Can be reduced. In addition, since the heat sink 26 is arranged on the rear side end surface of the rotating electrical machine, a large contact surface between the heat sink 26 and the outside air can be taken, so that the cooling performance of the power section is improved.
It should be noted that the present invention can be freely combined with each other within the scope of the invention, and each embodiment can be appropriately modified or omitted.

1 rotating electrical machine, 3 stator, 4 rotor, 5 rotating shaft, 9 sensor magnet,
11 Rotation angle sensor, 13 Stator core, 14 Stator winding, 18 Rotor core,
19 Permanent magnet, 24 arithmetic unit, 25 power transistor, 26 heat sink.

Claims (3)

A rotor and a stator disposed on the outer peripheral side of the rotor;
The stator includes a stator core and a stator winding,
The rotor includes a rotor core and a permanent magnet fixed to the outer peripheral surface of the rotor core,
In the center of the rotor core is a rotating electrical machine with a rotating shaft inserted,
The rotating shaft is configured to protrude only from one axial end surface of the rotor core, and the sensor magnet is an end surface of the rotor core where the rotating shaft does not protrude with respect to the rotor core. Rutotomoni directly fixed to the central position of the rotor core, the sensor magnet is the rotor core and the sensor magnet with respect to the rotation direction of the rotor core is installed to a predetermined phase,
The rotating electrical machine is characterized in that the rotational angle sensor is disposed with a gap in the axial direction with respect to the sensor magnet. 2. The rotating electrical machine according to claim 1, wherein the rotation angle sensor and an arithmetic unit for driving the rotating electrical machine using an angle signal output from the rotation angle sensor are attached to the same substrate. A power transistor that switches an energization current to the stator winding and a metal heat sink that cools the power transistor;
The rotation according to claim 1 or 2, wherein the rotor, the sensor magnet, the rotation angle sensor, the power transistor, and the heat sink are arranged in this order from one axial end side of the rotating electrical machine. Electric.

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