JP2007166771A - Stator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a stator that more effectively reduces the vibrations and noises of a dynamo-electric machine. <P>SOLUTION: In the stator 1, comprising a plurality of teeth 11b, on which stator coils are wound, and a yoke 11a that links a plurality of the teeth 11b, a piezoelectric element 13 that converts the vibrational energy of the corresponding teeth 11b into electrical energy is provided to each of the teeth 11b. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a stator used in a rotating electrical machine such as a motor.

  Japanese Patent Application Laid-Open No. 2004-228561 discloses a technique for damping vibration and noise of a motor by attaching a piezoelectric element (piezo element) to the motor and consuming electric energy generated in the piezoelectric element due to vibration of the motor with a load. Yes. In Patent Document 1, as a mode of attaching a piezo element to a motor, as shown in FIG. 11, a mode of attaching a ring-shaped piezo element 160 around the air inlet 141A of a fan case 141 of an electric blower 140, a fan case A mode in which a flexible piezo element 162 is attached to the peripheral wall surface 141B of 141, and a mode in which a cylindrical piezo element 164 is attached to the outside of the sound absorbing material of the motor case 142 are described.

JP 2002-369450 A JP-A-6-284754 JP 2000-116160 A JP 2002-359984 A JP 2005-20839 A

  By the way, in each tooth of the stator of the permanent magnet motor, an exciting force having an integer multiple of the number of poles of the rotor magnet is generated by the electromagnetic force between the rotor magnet and the stator teeth. For example, in an 8-pole motor, as shown in FIG. 12, an excitation force having a rotation order of an integer multiple of 8 is generated. FIG. 12 is a diagram showing the relationship between the rotational order actually measured for the 8-pole 48-slot motor and the excitation force gain.

  FIG. 13 shows theoretical spatial waveforms of the 48th-order component and the eighth-order component of the excitation force for an 8-pole 48-slot motor. As shown in FIG. 13, for the 48th-order component of rotation, the spatial wavelength coincides with the tooth interval, and force is applied to each tooth in the same direction. As for the rotating 8th order component, the spatial wavelength is 6 times the tooth interval, and a force is applied in the opposite direction every 3 teeth. In this way, the excitation force acts on each tooth at a different wavelength for each rotation order, and acts on a different phase for each tooth (excluding the rotation 48th-order component).

  The excitation force vibrates each tooth to generate motor vibration and noise (so-called motor electromagnetic sound (300 to 5 kHz)).

  As a technique for suppressing vibration and noise of the motor, the technique described in Patent Document 1 has been proposed. However, in this technique, only a piezo element is attached to a motor case or the like, and different vibrations are applied to each tooth. No consideration is given to the point where the force acts, and the vibration and noise of the motor cannot be effectively reduced.

  Therefore, the present invention provides a stator that can more effectively reduce vibration and noise of a rotating electrical machine.

  A stator according to the present invention is a stator having a plurality of teeth around which a stator coil is wound, and a yoke for connecting the plurality of teeth to each other, and vibration energy of the corresponding teeth is converted into electric energy for each of the teeth. A piezo element for conversion into the above is provided.

  In a preferred aspect of the present invention, the piezo element is embedded in the yoke at the base of the corresponding tooth.

  According to a preferred aspect of the present invention, there is provided a stator having a plurality of teeth around which a stator coil is wound and a yoke for connecting the plurality of teeth to each other, and vibrations of the teeth are applied to the yoke as electrical energy. Piezo elements to be converted into are embedded.

  In a preferred aspect of the present invention, both electrodes of the piezo element are electrically connected via the yoke.

  In a preferred aspect of the present invention, a circuit including a resistor and constituting a filter circuit together with the piezo element is connected between both electrodes of the piezo element.

  In a preferred aspect of the present invention, a negative feedback circuit is connected between both electrodes of the piezo element.

  Further, in a preferred aspect of the present invention, a voltage is applied to the piezoelectric element so that a deformation in the opposite direction to the deformation generated in the piezoelectric element due to the vibration of the corresponding teeth occurs between the electrodes of the piezoelectric element. A voltage application circuit to be applied is connected.

  ADVANTAGE OF THE INVENTION According to this invention, the stator which can reduce the vibration and noise of a rotary electric machine more effectively can be provided.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[First Embodiment]
FIG. 1 is a plan view showing a configuration of a stator 1 according to the first embodiment. In FIG. 1, the stator 1 has a substantially cylindrical shape, and mainly includes a stator core 11 and a stator coil (not shown) wound around the stator core 11. Here, the stator core 11 is a laminated core formed by laminating a plurality of electromagnetic steel plates. However, the structure of the stator core 11 is not limited to this, For example, a dust core etc. may be sufficient.

  The stator core 11 includes a substantially cylindrical stator yoke (hereinafter simply referred to as “yoke”) 11a, and a plurality (48 in this example) extending toward the central axis at predetermined intervals inside the yoke 11a. Stator teeth (hereinafter simply referred to as “teeth”) 11b. A stator coil (not shown) is wound around each tooth 11b.

  Inside the stator 1, for example, an eight-pole permanent magnet rotor (not shown) is disposed coaxially with the stator 1 via an air gap, thereby forming a permanent magnet motor. Although this permanent magnet motor can be applied to various uses, for example, it is suitably applied to an electric vehicle such as a hybrid vehicle including an electric motor as a drive source.

  In the present embodiment, as shown in FIG. 1, the yoke 11a has an insertion hole 12 for inserting a piezo element in the root portion of each tooth 11b (here, on the outer peripheral side of each tooth 11b). Yes. A rod-shaped piezo element 13 is inserted into each insertion hole 12.

  FIG. 2 is a partially enlarged view focusing on the specific piezoelectric element 13 of FIG. As shown in FIG. 2, both electrodes 13a and 13b of the piezo element 13 are arranged perpendicular to the projecting direction of the corresponding tooth 11b (the radial direction of the stator 1, the arrow X direction in FIG. 2). In the present embodiment, both electrodes 13a and 13b of the piezo element 13 are in contact with the cut surface of the yoke 11a (electromagnetic steel plate), and the two electrodes are electrically connected via the yoke 11a. ing.

  Next, the operation of the stator 1 according to the present embodiment will be described with reference to FIG. As shown in FIG. 3, when an excitation force F is applied to the teeth 11b and the piezo element 13 is distorted, the piezo element 13 generates an electromotive force due to the piezoelectric effect. As a result, a current flows through the electromagnetic steel plate between the electrodes of the piezo element 13 to generate heat loss, resulting in attenuation of vibration energy. That is, the vibration energy of the teeth 11b is converted into electric energy by the piezo element 13, and the electric energy is consumed as heat in the electromagnetic steel sheet. Thereby, the vibration energy of the teeth 11b is consumed.

  As described above, in the present embodiment, a piezo element that converts vibration energy of a corresponding tooth into electrical energy is provided for each tooth in a stator having a plurality of teeth. For this reason, according to the present embodiment, vibration energy for each tooth due to different excitation force for each tooth can be efficiently converted into electric energy by a piezoelectric element for each tooth, Noise (electromagnetic sound) can be effectively reduced.

  In the present embodiment, the piezoelectric element is embedded in the yoke at the base of the corresponding tooth. For this reason, according to the present embodiment, vibration energy can be more efficiently converted into electric energy, and vibration and noise of the motor can be reduced more effectively. Further, if the piezoelectric element is press-fitted into the yoke, the mechanical coupling between the electromagnetic steel sheets can be strengthened. Further, the magnetic steel sheets can be temporarily fixed, and a temporary fixing member can be dispensed with when the magnetic steel sheets are required to be temporarily fixed.

  In the present embodiment, both electrodes of the piezo element are electrically connected via a yoke, and electric energy is consumed by the yoke. Therefore, it is not necessary to provide a special power consumption circuit, and the motor can be manufactured at low cost. Vibration and noise can be reduced.

[Second Embodiment]
FIG. 4 is a schematic diagram showing the configuration of the stator 2 according to the second embodiment. Hereinafter, the stator 2 will be described with reference to FIG. 4, but since the present embodiment is almost the same as the first embodiment, common portions are denoted by the same reference numerals and description thereof is omitted. .

  In the present embodiment, the outer periphery of each piezo element 13 is insulated from the electrical steel sheet by the insulator 21. Between both electrodes of each piezo element 13, a circuit 22 including a resistor and constituting a filter circuit together with the piezo element 13 is connected. Specifically, the circuit 22 includes a series connection of an inductor L, a capacitor C, and a resistor R, or a series connection of an inductor L and a resistor R, and constitutes an LCR series resonance circuit together with a capacitance component of the piezo element 13 and the like. . Preferably, the resonance frequency of the filter circuit composed of the piezo element 13 and the circuit 22 is set so as to substantially match the frequency of the vibration to be damped, such as the natural frequency of the stator 2 or the frequency of an annoying sound. The

  The operation of the stator 2 having the above configuration will be described. When an excitation force is applied to the teeth 11b and the piezoelectric element 13 is distorted, the piezoelectric element 13 generates an electromotive force due to the piezoelectric effect. As a result, a current flows through the filter circuit composed of the piezo element 13 and the circuit 22, heat loss occurs in the resistor R, and vibration energy is attenuated as a result. At this time, the vibration is attenuated according to the frequency characteristic of the filter circuit (for example, the frequency characteristic as shown in FIG. 5). That is, a large resonance current is obtained in a frequency band near the resonance frequency of the filter circuit, and the vibration is selectively greatly attenuated.

  As described above, in the present embodiment, a circuit that includes a resistor and constitutes a filter circuit together with the piezoelectric element is connected between both electrodes of the piezoelectric element. For this reason, according to the present embodiment, it is possible to selectively attenuate vibrations in a desired frequency band by adjusting the frequency characteristics of the filter circuit.

  Further, if the frequency characteristics of the filter circuit are shifted for each tooth, vibrations in a plurality of frequency bands can be attenuated. For example, in the case where the natural frequency of the stator includes f1 and f2, if the filter circuit having the resonance frequency f1 and the filter circuit having the resonance frequency f2 are alternately provided along the teeth arrangement, the frequency bands f1 and f2 Vibration can be damped.

[Third Embodiment]
FIG. 6 is a schematic diagram showing the configuration of the stator 3 according to the third embodiment. Hereinafter, the stator 3 will be described with reference to FIG. 6, but since the present embodiment is almost the same as the first embodiment, common portions are denoted by the same reference numerals and description thereof is omitted. .

  In the present embodiment, the outer periphery of each piezo element 13 is insulated from the magnetic steel sheet by the insulator 31. A negative feedback circuit 32 is connected between both electrodes of each piezo element 13.

  FIG. 7 is a circuit diagram illustrating an example of the negative feedback circuit 32. In FIG. 7, the negative feedback circuit 32 includes an NPN transistor Tr. The base of the transistor Tr is connected to the positive electrode of the DC power source E through the resistor R1, and is connected to one electrode of the piezo element 13 through the capacitor C1. The other electrode of the piezo element 13 is connected to the ground. The collector of the transistor Tr is connected to the positive electrode of the DC power supply E via the resistor R2 and to one electrode of the capacitor C2. The other electrode of the capacitor C2 is connected to the output terminal OUT and connected to the ground via the resistor RL. The emitter of the transistor Tr is connected to the ground via a resistor RE.

  The operation of the stator 3 having the above configuration will be described. When an excitation force is applied to the teeth 11 b and the piezo element 13 is distorted, an input voltage is generated for the negative feedback circuit 32. Then, as shown in FIG. 8, the negative feedback circuit 32 feeds back a feedback voltage (solid line in FIG. 8) having an opposite phase to the piezoelectric generation voltage (broken line in FIG. 8) to the piezo element 13. Since this feedback voltage acts in a direction that distorts the piezo element 13 in the direction opposite to the input, vibration is reduced.

  As described above, in this embodiment, the negative feedback circuit is connected between both electrodes of the piezo element. For this reason, according to the present embodiment, the feedback current automatically changes according to the magnitude of the distortion of the piezo element, so that a damping effect according to the magnitude of the vibration can be obtained.

[Fourth Embodiment]
FIG. 9 is a schematic diagram showing the configuration of the stator 4 according to the fourth embodiment. Hereinafter, the stator 4 will be described with reference to FIG. 9, but since the present embodiment is almost the same as the first embodiment, common portions are denoted by the same reference numerals and description thereof is omitted. .

  In the present embodiment, the outer periphery of each piezo element 13 is insulated from the electrical steel sheet by the insulator 41. A voltage application circuit 42 is connected between both electrodes of each piezo element 13. The voltage application circuit 42 is a circuit that applies a voltage to the piezo element 13 such that the piezo element 13 undergoes deformation in a direction opposite to that generated in the piezo element 13 due to vibration of the teeth 11b. Specifically, the voltage application circuit 42 applies a voltage to the piezo element 13 that causes the piezo element 13 to undergo deformation in the opposite direction to the piezo element 13 estimated from the rotation angle of the rotor and the stator current. Apply.

  The voltage application circuit 42 can be realized with an appropriate configuration. In the configuration example shown in FIG. 9, the amplifier 42a that applies a voltage to the piezo element 13 based on a drive signal from the outside, and the amplifier 42a is driven. And a waveform generation circuit 42b for supplying a signal. A motor ECU (electronic control unit) 51 that controls the motor including the stator 4 is connected to the waveform generation circuit 42b. A resolver 53 is connected to the motor ECU 51 via an RD converter 52, and a current sensor 54 for detecting a current flowing in the stator coil is connected. Here, the resolver 53 outputs a signal corresponding to the rotation angle of the rotor to the RD converter 52, and the RD converter 52 outputs a current phase signal to the motor ECU 51 based on the signal from the resolver 53. Further, the current sensor 54 outputs a signal of the peak value of the stator current to the motor ECU 51. The motor ECU 51 outputs the current phase signal input from the RD converter 52 and the peak value signal input from the current sensor 54 to the waveform generation circuit 42b.

  The operation of the stator 4 having the above configuration will be described. The waveform generation circuit 42b receives signals of current phase and peak value from the motor ECU 51, and based on these signals, the voltage (magnitude) generated in each piezo element 13 by the force of each rotational order input to each tooth 11b. And phase). Then, the waveform generation circuit 42b outputs a drive signal to the amplifier 42a so that a voltage obtained by inverting the phase of the calculated voltage is applied to the piezo element 13. Based on the drive signal from the waveform generation circuit 42b, the amplifier 42a, as shown in FIG. 10, is a voltage (control voltage, diagram) obtained by inverting the phase of the calculated voltage (piezo generation voltage, broken line in FIG. 10). 10) is applied to the piezo element 13. Here, from the viewpoint of effectively suppressing the vibration of the teeth 11b, the control voltage is preferably higher than the piezoelectric generation voltage. However, the control voltage may be equal to or smaller than the piezoelectric generation voltage.

  As described above, in the present embodiment, the piezoelectric element 13 is applied with a voltage obtained by inverting the voltage generated when the force is applied to the teeth 11b and the piezoelectric element 13 is distorted. Arise. The excitation force is canceled by the antiphase force generated in the piezo element 13, and the vibration of the teeth 11b is suppressed.

  As described above, in the present embodiment, a voltage is applied to the piezo element so that the piezo element undergoes deformation in the opposite direction to the deformation that occurs in the piezo element due to the vibration of the teeth. For this reason, according to the present embodiment, it is possible to actively cancel the vibration of the teeth by using the force due to the inverse piezoelectric effect of the piezoelectric element, and a great vibration damping effect can be obtained.

  For example, in an electric vehicle such as a hybrid vehicle, if the voltage application circuit is configured to apply a control voltage having the same phase as the piezo generated voltage to the piezo element in accordance with an instruction from the user, the electromagnetic sound is And a function (caring horn) that emits a warning sound that is kind to pedestrians and other drivers can be realized.

  In addition, this invention is not limited to the said embodiment, It can change variously within the range which does not deviate from the summary of this invention. For example, the circuit connected to both poles of the piezo element 13 is not limited to that shown in the above embodiment, and may be another power consuming circuit that consumes the electric energy of the piezo element 13. Moreover, although the case where the stator of the present invention is applied to an inner rotor type permanent magnet motor is illustrated in the above embodiment, the stator of the present invention is applied to other rotating electric machines such as other types of motors and generators. Is also applicable.

  In the second embodiment, the filter circuit may be configured so that the resonance frequency is variable, and control may be performed to change the resonance frequency of the filter circuit according to the rotor rotational speed. According to this configuration, it is possible to appropriately cope with a change in vibration frequency according to the rotor rotational speed.

  In the fourth embodiment, vibration may be actually measured, and a voltage may be applied from the voltage application circuit 42 to the piezo element 13 so that vibration having an opposite phase to the measured vibration occurs.

  In the above embodiment, the piezoelectric element 13 is embedded in the yoke 11a. However, the installation position of the piezoelectric element 13 is not limited to this, and may be attached to the outer peripheral surface of the yoke 11a, for example.

  According to the configuration in which the piezoelectric element that converts the vibration of the teeth into electrical energy is embedded in the yoke, the vibration of the teeth is more efficient than the configuration in which the piezoelectric element is installed at other positions (for example, the motor case or the outer wall of the yoke). Can be converted into electrical energy, and vibration can be effectively reduced. Such an effect can be obtained without necessarily providing a piezo element for each tooth. For example, the above effect can be obtained even if one piezoelectric element is provided for N teeth (N is an integer of 2 or more).

It is a top view which shows the structure of the stator which concerns on 1st Embodiment. It is the elements on larger scale which paid its attention to the specific piezoelectric element of FIG. It is a figure for demonstrating the effect | action of the stator which concerns on 1st Embodiment. It is the schematic which shows the structure of the stator which concerns on 2nd Embodiment. It is a figure which shows the frequency characteristic of the filter circuit in 2nd Embodiment. It is the schematic which shows the structure of the stator which concerns on 3rd Embodiment. It is a circuit diagram which shows an example of the negative feedback circuit in 3rd Embodiment. It is a wave form diagram which shows the piezo generation voltage and feedback voltage in 3rd Embodiment. It is the schematic which shows the structure of the stator which concerns on 4th Embodiment. It is a wave form diagram which shows the piezo generation voltage and control voltage in 4th Embodiment. It is an exploded perspective view of the electric blower described in patent documents 1. It is a figure which shows the relationship between a rotation order and excitation force gain. It is a wave form diagram of the rotation 48th-order component and rotation 8th-order component of an exciting force.

Explanation of symbols

  1-4 Stator, 11 Stator core, 11a Yoke, 11b Teeth, 12 Insertion hole, 13 Piezo element, 13a, 13b Electrode, 21, 31, 41 Insulator, 22 circuit, 32 Negative feedback circuit, 42 Voltage application circuit, 42a Amplifier , 42b waveform generation circuit, 51 motor ECU, 52 RD converter, 53 resolver, 54 current sensor.

Claims (7)

A stator having a plurality of teeth around which a stator coil is wound, and a yoke for connecting the plurality of teeth to each other,
A stator comprising a piezoelectric element for converting vibration energy of a corresponding tooth into electric energy for each tooth. The stator according to claim 1,
The stator is characterized in that the piezo element is embedded in the yoke at the base of a corresponding tooth. A stator having a plurality of teeth around which a stator coil is wound, and a yoke for connecting the plurality of teeth to each other,
A stator in which a piezo element for converting vibration of the teeth into electric energy is embedded in the yoke. The stator according to claim 2 or 3,
A stator in which both electrodes of the piezo element are electrically connected via the yoke. The stator according to any one of claims 1 to 3,
A stator comprising a resistor between both electrodes of the piezo element, and a circuit constituting a filter circuit together with the piezo element. The stator according to any one of claims 1 to 3,
A stator comprising a negative feedback circuit connected between both electrodes of the piezoelectric element. The stator according to any one of claims 1 to 3,
A voltage applying circuit for applying a voltage to the piezo element is connected between both electrodes of the piezo element so that the piezo element undergoes deformation in a direction opposite to that caused by the vibration of the corresponding tooth. A stator characterized by that.

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