JP2019075927A - Electric motor - Google Patents

Abstract

To provide an electric motor capable of reducing vibration and noise to be generated by a motor.SOLUTION: An electric motor 1 comprises a stator 3 which has a cylindrical part 7, a plurality of stator teeth 20 projecting toward the inside of the cylindrical part 7, and a coil 8 wound around the stator teeth 20, and a rotor 2 which rotates on a center axis of the cylindrical part 7, wherein one end in the cylindrical part 7 is fastened to a stationary part 5 so as to close the one end. The electric motor further comprises: an annular hub 21 provided on the center axis of the cylindrical part 7; and a plurality of columns 19 coupled with the hub 21. In the plurality of columns 19, one ends are coupled with the hub 21, and the other ends are coupled with the other ends in the cylindrical part 7.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a structure for suppressing (reducing) vibration and noise due to power generated by an electric motor.

  For example, a large motor such as a motor used as a driving force source of a vehicle generates relatively large torque. Also, the motor is not housed alone in the casing but is housed in the casing together with peripheral members such as bearings. The motor of this type is configured to suppress the vibration with respect to the torque generated by the motor. Patent Document 1 describes an example of a configuration that suppresses vibration in the motor.

  The motor described in Patent Document 1 includes an annular stator, a rotor accommodated on the inner peripheral side of the stator, and a motor case accommodating the stator. Further, an inner frame (supporting member) for fixing one end in the axial direction of the stator to the motor case is provided, and the stator is configured to be supported by the motor case via the inner frame. Furthermore, in the motor described in Patent Document 1, when the stator is fixed to the motor case via the above inner frame, vibration and noise in the radial direction are suppressed. Specifically, a clearance is provided between the outer peripheral surface of the stator in the radial direction and the inner peripheral surface of the motor case in the radial direction, and the motor case is not supported in the radial direction. The stator is configured to be fixed to the motor case via the frame. On the other hand, in the case of fixing in the radial direction, a thinned portion is formed in the circumferential direction on the outer side in the radial direction of the inner frame. The motor described in Patent Document 1 has a cantilever structure in which the stator is supported at one end in the axial direction in order to suppress the above-mentioned vibration in the radial direction. It is being fixed by the fastening member.

Patent No. 5862831 gazette

  The stator in the motor as described in Patent Document 1 is composed of a stator core and an electromagnetic coil, and generates a torque by energizing the electromagnetic coil, that is, the stator is an oscillating source of vibration, The generated vibrations are relatively large, for example, on the outer peripheral side (radial direction) of the stator core. Therefore, in order to suppress the vibration, it is effective to suppress the vibration in the radial direction of the stator as described in Patent Document 1. In the configuration described in Patent Document 1, as described above, a clearance is provided between the stator and the motor case, and the stator is fixed to the motor case in the axial direction via the inner frame, or the outer periphery of the inner frame By forming a lightening portion on the side, vibration in the radial direction is suppressed. On the other hand, in the configuration described in Patent Document 1, as described above, since the stator is supported on the motor case in a cantilevered structure, the rigidity on the head side of the bolt for fixing the stator to the motor case is low. . Therefore, as described in Patent Document 1, even when the vibration in the radial direction is reduced, the vibration may still be insufficient to suppress the vibration, and there is room for improvement.

  SUMMARY OF THE INVENTION The present invention has been made in consideration of the above technical problems, and an object thereof is to provide a motor capable of reducing vibration and noise generated by the motor.

  In order to achieve the above object, the present invention provides a stator having a cylindrical portion, a plurality of stator teeth projecting toward the inside of the cylindrical portion, and a coil wound around the stator teeth, and the cylinder An electric motor having a rotor rotating about a central axis of the part, wherein one end of the cylindrical part is fastened to the fixed part so as to close the one end, provided on the central axis of the cylindrical part Annular hub and a plurality of pillars connected to the hub, the plurality of pillars having one end connected to the hub and the other end being the other end of the cylindrical portion It is characterized in that it is connected to

  According to the motor of the present invention, one end of the stator is configured to reinforce the other end in a state of being fastened to the fixing portion so as to close the end (cantilever state) . Specifically, an annular hub provided on a central axis of a cylindrical portion constituting the stator and a plurality of columns connected to the hub are provided. Further, one end of each of the plurality of pillars is connected to the hub, and the other end is connected to the end of the cylindrical portion opposite to the fixed portion. Thus, by reinforcing the opposite end of the cylindrical portion fastened to the fixed portion with the hub and the plurality of columns, for example, the vibration transmitted from each column toward the hub and the hub The vibration transmitted to each column is canceled (cancelled) or reduced. That is, the vibration in the radial direction described above can be reduced, so that the vibration generated by the torque of the motor can be reduced.

It is a sectional view showing typically one embodiment of this invention. It is a figure explaining the example which provided three pillars in a reinforcement member in the structure of FIG. It is a figure explaining the example which provided eight pillars in a reinforcement member in the structure of FIG. It is a figure explaining the example which provided ten pillars in a reinforcement member in the structure of FIG. It is a graph which shows the relationship of the frequency and vibration in the example of FIGS. 2-4 and FIG. It is a figure explaining the other example of the reinforcement member in embodiment of this invention. It is a reference example to be compared with the configuration of FIG. 2 to FIG.

  An embodiment of the present invention will be described. An electric motor (motor generator) according to the present invention is used as a power source of, for example, a hybrid vehicle or an electric vehicle, and is a three-phase induction motor, a permanent magnet synchronous motor (PM motor), or the like. In addition, this motor (hereinafter referred to as a motor) has both a function (powering function) as a motor driven by supply of electric power and a function (regeneration function) as a generator for converting mechanical energy into electric energy. There is. Hereinafter, the motor 1 will be specifically described with reference to the drawings.

  FIG. 1 is a view schematically showing a motor according to an embodiment of the present invention, and a rotor (rotor) 2 which is a main component of the motor 1 and a stator (stator) 3 are inside the motor. Is located in The rotor 2 and the stator 3 may be similar to those of general configurations conventionally known. Specifically, the stator 3 has an annular shape and is formed in a tubular shape, and the rotor 2 is enclosed in a tubular shape and accommodated therein, and the inner peripheral surface of the rotor 2 is cylindrical. It is disposed to face the outer peripheral surface. Further, as shown in FIG. 1, an air gap 4 is a gap where the inner peripheral surface of the stator 3 and the outer peripheral surface of the rotor 2 face each other. In other words, in the motor 1, the rotor 2 is rotatably supported together with the rotor shaft 2 a in the inner peripheral portion of the stator 3 with a predetermined slight air gap 4 in the radial direction. A magnetic attraction force in which the stator 3 and the rotor 2 work with each other is determined by the air gap 4, and the interval is set by the size of the motor 1 or the like.

  In addition, a casing 5 is provided on the outer peripheral side of the stator 3 so as to cover the outer peripheral surface thereof, and the stator 3 is accommodated in the casing 5 and fixed by a fastening member 6 such as a bolt. The stator 3 is configured as an electromagnet having a stator core 7 in which a plurality of electromagnetic steel plates are arranged and stacked, and an electromagnetic coil 8 in which a lead such as a copper wire is wound. The electromagnetic coil 8 wound around the stator core 7 is configured to generate torque in the rotor 2 by changing the current flow to change the magnetic field, and the axial direction of the stator core 7 at both ends of the electromagnetic coil 8 The folded portion is a coil end 9 of the electromagnetic coil 8. The coil end 9 is provided with an insulating film. Further, the above-mentioned casing 5 corresponds to the "fixed portion" in the embodiment of the present invention, and the stator core 7 corresponds to the "cylindrical portion" in the embodiment of the present invention.

  Then, a lead wire (not shown) connected and connected to the electromagnetic coil 8 is electrically connected to an inverter (not shown), and is electrically connected from the inverter to the battery by another lead wire. For example, when the motor 1 is a three-phase AC motor, a terminal box (not shown) having a U terminal, a V terminal and a W terminal, etc. is provided in the casing 5 and the conductors from the inverter are respectively provided. Wired Further, in the inverter, the operation of the driver's accelerator pedal and brake pedal (both not shown) is detected by a sensor (not shown), and the operation of the inverter via the electronic control unit (not shown) is performed. Information representative of the situation is communicated as an electrical signal. Then, when the inverter receives the electric signal, the inverter instructs the battery to an amount of electric power, converts the direct current from the battery into an alternating current, and supplies the electric power to the motor.

  On the other hand, the rotor 2 rotates about the central axis O of the above-mentioned stator, has a hollow cylindrical rotor shaft 2a on the central axis O, and the rotary shaft 10 is inserted into the rotor shaft 2a so as to be relatively rotatable. It is done. The rotation shaft 10 rotates about a central axis O (hereinafter, also simply referred to as an axial direction), has a predetermined length in the axial direction, and can transmit power to a power transmission element or the like (not shown).

  The rotor 2 has a rotor core (rotor core) 11 formed of laminated steel plates, and is attached to the rotor shaft 2a in a state where a load is applied in the axial direction and tightened so that the steel plates are in close contact. Specifically, mounting members (locking portions) 12 and 13 integral with the rotor shaft 2 a are provided on both end sides of the rotor 2 in the axial direction. As a result, both end surfaces of the rotor 2 abut and are sandwiched, and the position of the rotor 2 in the axial direction is defined.

  Furthermore, the rotor 2 shown in FIG. 1 has an end plate (end plate) 14 at the end of the rotor 2 that abuts one of the fixtures 12 (13). The end plate 14 is configured to prevent the plurality of electromagnetic steel plates having the laminated structure of the rotor core 11 from being sandwiched and dispersed. That is, the magnetic steel plates are attached to the rotor shaft 2a in a state in which a load is applied in the axial direction so as to be in close contact with each other and tightened. The rotor shaft 2a is fixed to the rotor shaft 2a by an appropriate method such as screwing, caulking, or press-fitting, and rotates integrally with the rotor shaft 2a. Thus, since the end plate 14 is fastened, the rotor core 11 also rotates integrally with the end plate 14. The end plate 14 and the plurality of electromagnetic steel plates are configured such that fastening members such as screws and bolts are inserted into and fastened to the end plate 14 and the plurality of electromagnetic steel plates, and integrally rotate. It is also good.

  The end of the rotor shaft 2a is rotatably supported on the casing 5 by a bearing member 15 such as a ball bearing, and the rotation shaft 10 is also rotatably supported on the casing 5 by the bearing member 16.

  The motor 1 configured as described above is applied to a hybrid vehicle or an electric vehicle as described above, and generates and drives power (torque) by supplying power, for example. Specifically, when the electromagnetic coil 8 provided in the stator 3 is energized, the rotor 2 is rotated (driven) by the electromagnetic force generated by the stator 3. The power output from the motor 1 is transmitted as a rotational force to a wheel (not shown) via an output shaft (not shown), and the vehicle can be made to travel by integrally rotating the wheel with the output shaft. . Further, at the time of regeneration, the wheel is rotated by the inertial force of the vehicle body, and the motor 1 is driven through the output shaft by the rotational force from the wheel. At this time, the motor 1 operates as a generator, and the generated electric power is stored in the battery via the inverter.

  On the other hand, since the motor used as a driving force source of the vehicle in this manner generates a relatively large torque, the generated vibration and the accompanying noise become large accordingly. For example, it vibrates at the time of generation of driving force as a motor and at the time of power generation as a generator. Specifically, as described above, since the torque is generated by energizing the electromagnetic coil 8, the stator core 7 becomes an oscillation source of vibration, and such generated vibration is generated, for example, between the rotor 2 and the stator 3. The distance between the air gaps 4 fluctuates and becomes relatively large in the radial direction (outer peripheral side) of the stator core 7. Therefore, vibration and noise are generated by such electromagnetic excitation force in the radial direction of the stator 3. Further, as described above, in order to reduce (or suppress) radial vibration, it is preferable to use a cantilever structure supported at one end of the stator, and from the viewpoint of assemblability, the cantilever structure is preferable. . Therefore, when the stator 3 is supported with respect to the casing 5 in such a cantilever structure, the rigidity on the head side of the fastening member 6 for fastening the stator 3 to the casing 5 is reduced, and vibration and noise in the radial direction are more There is a risk of becoming large. Therefore, in the embodiment of the present invention, the vibration and the noise are reduced.

  Specifically, a reinforcing member 17 is provided to reduce the vibration and noise. The reinforcing member 17 has a cylindrical portion 18 continuously connected to the outer peripheral portion of the stator 3, ie, the stator core 7 in the axial direction, and a plurality of columns (stiffeners or beams so as to partially close the opening of the cylindrical portion 18). And 19). The cylindrical portion 18 may not have a structure in which a plurality of electromagnetic steel plates are stacked as in the stator core 7.

  2 to 4 show an example showing the stator 3 provided with the reinforcing member 17, and FIG. 2 shows an example provided with three columns 19 and FIG. 3 shows an example provided with eight columns 19 FIG. 4 shows an example in which ten columns 19 are provided. FIG. 7 is a reference example showing an example of a motor in which such a reinforcing member 17 is not provided, such as Patent Document 1 mentioned above. Although the inner peripheral side of the stator 3 in FIGS. 2 to 4 and 7 has a smooth shape (reference numeral 20), in the actual stator 3, a plurality of grooves are formed on the inner peripheral side of the stator 3 The plurality of grooves formed correspond to stator teeth (or slots) 20 in which the electromagnetic coil 8 is wound.

  More specifically, the reinforcing member 17 is configured such that a part of the opening of the cylindrical portion 18 is closed as described above, and the cylindrical portion 18 and the rotor shaft 2a are inserted. An annular center hub 21 and a pillar 19 radially extending from the center hub 21 in the radial direction. Further, a plurality of the columns 19 is provided, and the number of the columns 19 is an appropriate number as shown in FIGS. 2 to 4 described above. As shown in FIGS. 1 and 2, a predetermined clearance C is provided between the rotor shaft 2 a and the center hub 21 in consideration of bending of the column 19 and the like. The stator 3 is fixed by the above-described fastening member (bolt) 6 via the reinforcing member 17. In addition, the code | symbol 6a shown to FIGS. 2-4 is a hole in which the fastening member 6 is inserted.

  In addition, it is preferable that the intervals of each column 19 provided radially be configured at equal intervals in the circumferential direction, and in the example illustrated in FIGS. 2 to 4, the intervals of each column 19 in the circumferential direction are configured to be equal. That is, the distance between values obtained by dividing the number of columns 19 in the circumferential direction (360 °). That is, in the example shown in FIG. 2, the number of the pillars 19 is three, so the pillars 19 are provided at an interval of 120 °.

  Furthermore, in the embodiment of the present invention, it is preferable to determine the number of columns 19 in the reinforcing member 17 in accordance with the number of poles of the motor 1. FIG. 5 shows the relationship between vibration and frequency when the reinforcing member 17 is provided for an 8-pole motor. Specifically, for an 8-pole motor without the reinforcing member 17 (example in FIG. 7), when the number of the columns 19 of the reinforcing member 17 is three (example in FIG. 2), the columns of the reinforcing member 17 In the case where the number of 19 is eight (example in FIG. 3), the case where the number of the columns 19 of the reinforcing member 17 is ten (example in FIG. 4) is compared based on each example. Each line in FIG. 5 shows a change in vibration according to the number of the columns 19 of the reinforcing member 17 in each example, the vertical axis shows the vibration, and the horizontal axis shows the frequency. The solid line shows an example where the number of columns 19 of the reinforcing member 17 is eight, the broken line shows an example where there is no reinforcing member, and the dashed dotted line shows when the number of columns 19 of the reinforcing member 17 is ten. An example of the case where the number of the columns 19 of the reinforcing member 17 is three is shown.

  As shown in FIG. 5, the value of the vibration has a peak at a predetermined frequency α. At this peak point, when there are no reinforcing members 17, the number of columns 19 of the reinforcing members 17 is three, eight or ten. It can be understood that the vibration value is the largest. Then, the vibration value decreases in the order of ten, three, and eight columns 19 of the reinforcing member 17, that is, in this 8-pole motor, the reinforcing member indicated by the solid line in the vibration at the peak point. The case where the number of pillars 19 at 17 is eight is the smallest. From this result, in the embodiment of the present invention, it is preferable to provide pillars 19 corresponding to the number of poles, and in the case of an eight-pole motor, it is preferable to provide eight pillars 19.

  Next, the operation of the embodiment of the present invention will be described. As described above, in the examples shown in FIGS. 2 to 4, the reinforcing member 17 for reducing the vibration of the motor 1 is provided. Specifically, the reinforcing member 17 is provided on the inner peripheral side of the cylindrical portion 18 provided so as to be continuous in the axial direction, so that the plurality of pillars 19 are centered so as to partially close the opening of the cylindrical portion 18 It is provided radially from the hub 21. Each of the plurality of columns 19 has one end connected to the center hub 21 and the other end connected to the end of the stator core 7 opposite to the casing 5 (cylindrical in the example of FIGS. 2 to 4 Unit 18). Accordingly, by thus reinforcing the casing 5 and the end opposite to the casing 5 by the center hub 21 and the plurality of columns 19, for example, the vibration transmitted from each column 19 toward the center hub 21 and the center hub Since the vibrations transmitted from the point 21 to each column 19 cancel each other, the vibrations are reduced. That is, the vibration in the radial direction described above can be reduced, so that the vibration generated by the torque of the motor 1 can be reduced.

  Further, in each of the above-described examples, the plurality of columns 19 are provided at equal intervals radially in the circumferential direction. Therefore, the vibration received by the center hub 21 is uniformly dispersed in the circumferential direction, and the vibration and the vibration transmitted from each pillar 19 to the center hub 21 cancel each other, so that the vibration can be further reduced. In other words, by providing the respective columns 19 at equal intervals in such a manner, the balance as the entire reinforcing member 17 can be maintained, so the durability as the entire reinforcing member 17 and the stator 3 can be reduced while reducing the vibration. It can be improved.

  Moreover, in addition to the ability to reduce the vibration and noise in the radial direction described above, the vibration (ring vibration) in the circumferential direction of the stator 3 can also be reduced by the same action. And as shown in the experimental result shown in FIG. 5, the vibration at the peak time can be reduced by matching the number of poles 19 with the number of poles.

  As mentioned above, although several embodiment of this invention was described, this invention is not limited to the example mentioned above, Comprising: You may change suitably in the range which achieves the objective of this invention. As described above, it is preferable to make the number of columns 19 of the reinforcing member 17 correspond to the number of poles of the motor 1. On the other hand, the number of columns 19 may be N times (i.e., a multiple) of the number of poles, and may be 8, 16, 24 in the case of an 8-pole motor, for example. Further, in the above-described example, although the shape of the center hub 21 is formed by an annular circle, as shown in FIG. 6, for example, in the case of an 8-pole motor, this shape is a regular octagon according to the number of poles. (Or, N times the shape) may be used. Further, correspondingly, the shape of the end face of the cylindrical portion 18 connected via the column 19 may be similar.

  Furthermore, in each of the examples described above, although the reinforcing member 17 is constituted by the cylindrical portion 18 continuously connected to the stator 3, the center hub 21, and the plurality of columns 19, it is not limited thereto. The cylindrical portion 18 may not be provided. That is, when the electromagnetic coil 8 does not protrude in the axial direction from the stator core 7 as in the above-described example, the reinforcing member 17 may be configured to close a part of the opening on one side of the stator 3 .

  DESCRIPTION OF SYMBOLS 1 ... motor (motor generator), 2 ... rotor, 3 ... stator, 7 ... stator core, 8 ... coil, 17 ... reinforcement member, 19 ... pillar (stiffener), 20 ... stator teeth, 21 ... center hub, O ... center Axis.

Claims (1)

A stator having a cylindrical portion, a plurality of stator teeth projecting toward the inside of the cylindrical portion, a coil wound around the stator teeth, and a rotor rotating around a central axis of the cylindrical portion A motor in which one end of the cylindrical portion is fastened to the fixed portion so as to close the one end,
An annular hub provided on a central axis of the cylindrical portion;
And a plurality of columns connected to the hub;
The motor according to claim 1, wherein the plurality of columns have one end connected to the hub and the other end connected to the other end of the cylindrical portion.

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