JP2000060060A - Motor with control unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively reduce noise with a simple constitution by providing a silencer which damps a prescribed frequency of acoustic waves generated from a motor section in a control case. SOLUTION: A control unit 8 is positioned on the right side of a motor section 1 in the axial direction. The unit 8 is constituted by providing an inverter device 10 in a control case 9. The inverter device 10 is provided with capacitors 12 and a switching element 13 mounted on a control circuit board 11 and constitutes a control circuit, etc. The space 14 in the case 9 is communicated with the inside of the motor section 1 which generates acoustic waves through a hole 15 formed through a bearing bracket 2c. The space 14 and hole 15 constitute a silencer 16. When the damping frequency of the silencer 16 is made coincident with the frequency of principal noise in the frequency band of a carrier for controlling inverter, the noise can be damped efficiently.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor with a control unit having a control unit in a motor section.

[0002]

2. Description of the Related Art As a motor, there is a motor with a control unit in which a control unit is integrally provided in a motor unit. In this type of motor, the motor unit has a configuration having a stator and a rotor in a motor frame, and the control unit has a configuration in which an inverter device is provided in a control case. As is well known, the inverter device includes a DC power supply circuit, a switching circuit that switches DC power from the DC power supply circuit, and a control circuit that controls ON / OFF of a switching element of the switching circuit. Circuits include electronic components such as capacitors and I
A switching element such as a GBT is included. By the way, when the motor is operated, noise mainly at the carrier frequency of the inverter control is generated, and this noise is quite loud and becomes a problem when the motor is operated.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide a motor with a control unit which can effectively reduce noise with a simple structure. .

[0004]

According to a first aspect of the present invention, there is provided a motor unit having a stator and a rotor in a motor frame;
A control unit provided with an inverter device in the control case, a bearing bracket provided between the motor frame and the control case, and a silencer for attenuating a predetermined frequency of sound waves generated from the motor unit. It is characterized by being provided inside.

According to this configuration, the noise generated from the motor can be effectively reduced. According to the second aspect of the present invention, the muffler is constituted by the hole provided in the bearing bracket and the space in the control case, and it is not necessary to provide another muffler, and the control case serving as the cover of the inverter device can be effectively used. Available.

According to a third aspect of the present invention, there is provided a motor unit having a stator and a rotor in a motor frame, and a control unit provided with an inverter device in a control case, wherein a bearing is provided between the motor frame and the control case. The present invention is characterized in that a control unit provided with a bracket is provided, and a resonator for resonating sound waves generated from the motor unit is provided in the control case.

According to this configuration, the noise generated from the motor can be effectively reduced as in the first aspect of the present invention. The invention according to claim 4 includes a motor unit having a stator and a rotor in a motor frame, and a control unit in which an inverter device is provided in a control case, and a bearing bracket is provided between the motor frame and the control case. ,And,
An interference body having a first passage and a second passage that bypasses the first passage is provided in the control case, and the length of the second passage is reduced by the length of the first passage from the motor unit. It is characterized in that it differs by a length obtained by multiplying a half wavelength of a generated sound wave of a predetermined frequency by an integer.

According to this structure, the sound wave from the first passage and the sound wave from the second passage are superimposed on each other in a phase opposite to each other, so that the sound wave is canceled out and the noise is attenuated. .

According to a fifth aspect of the present invention, there is provided a motor unit having a stator and a rotor in a motor frame, and a control unit provided with an inverter device in a control case, wherein a bearing is provided between the motor frame and the control case. The present invention is characterized in that a control unit provided with a bracket is provided, and dimensions of three sides of the control case are set to lengths that do not coincide with wavelengths of sound waves of a predetermined frequency generated from the motor unit.

According to this configuration, sound waves of a predetermined frequency generated from the motor section can be effectively reduced.
The invention of claim 6 is characterized in that cooling fins are provided on the motor frame and the control case, and the natural frequency of these cooling fins and the predetermined frequency of the sound wave generated from the motor unit are not made to match.

According to this configuration, since the natural frequencies do not coincide with each other, radiation noise to the outside of the case is reduced. The invention according to claim 7 is characterized in that cooling fins are provided in the motor case and the control case, and the interval between the cooling fins is set so that the wavelength of the sound wave generated from the motor unit does not coincide with the natural frequency of the cooling fins. Have. According to this configuration, sound waves generated from the motor unit can be effectively reduced.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIGS. The motor unit 1 includes an outer portion formed by a motor frame 2, and the motor frame 2 is configured by connecting bearing brackets 2b and 2c to a cylindrical portion 2a. A stator 3 having a stator core 3a and a winding 3b is arranged on the inner surface of the cylindrical portion 2a. A rotating shaft 6 is rotatably supported on the bearing brackets 2a and 2c via bearings 4 and 5, and a rotor 7 is mounted on the rotating shaft 6. And this rotor 7
Has a left end projecting from the bearing bracket 2a and serving as an output shaft.

A control unit 8 is provided on the right side of the motor unit 1 in the axial direction. The control unit 8 includes an inverter device 10 provided in a control case 9. The inverter device 10 includes a capacitor 12 and a switching element (IGB) provided on a control circuit board 11.
T) 13 to constitute a DC power supply circuit, an inverter main circuit, and a control circuit.

A space 14 in the control case 9 has an internal volume V. The space 14 communicates with the inside of the motor unit 1 which is a sound source via a hole 15 provided in the bearing bracket 2c. The space 14 and the hole 15 constitute a silencer 16. Here, the attenuation frequency in the silencer 16 is obtained by the following equation (1).

[0015]

(Equation 1)

Here, c is the speed of sound, V is the internal volume of the silencer 16, that is, the volume of the space excluding the inverter device 10 and the control circuit in the control case 9, and Co is the conductivity of the sound of the hole 15 ( Conductivity). When the hole 15 is circular as in the present embodiment, Co is expressed by the following equation (2).

[0017]

(Equation 2)

Here, n is the number of the holes 15, a is the radius of the holes 15, and l is the length (depth) of the holes 15. The attenuation frequency fr is determined by appropriately selecting V, n, and l in consideration of Expressions (1) and (2).

According to this embodiment, the noise can be efficiently attenuated by setting the attenuation frequency of the muffler 16 to the frequency of the main noise in the carrier frequency band of the inverter control, for example. For example, the operation of the motor generates noise mainly at the carrier frequency of the inverter control, and the fundamental frequency of the noise is 1000H.
If z, the attenuation frequency of the silencer 16 is also 1000 Hz
Since V, n, and l are set so as to be equal to the fundamental frequency of the noise, a sound wave of this frequency is transmitted from the hole 15 of the bearing bracket 2c, and the air of the silencer 16 resonates and the hole 15 The air in the portion vibrates violently, and the sound energy is mainly converted to thermal energy due to friction in the hole 15 portion, and the noise mainly in the frequency band near 1000 Hz is effectively attenuated.

FIG. 2 is a comparative diagram showing the effect of noise reduction. FIG. 3 shows a second embodiment of the present invention, and different points from the first embodiment will be described.

Reference numeral 17 denotes a resonator provided in the control case 9.
This resonator 17 has an internal volume V, and the bearing bracket 2c
In communication with the hole 15 provided in the hole. This resonator 17
Is obtained by the following equation (3).

[0022]

(Equation 3)

Here, c is the speed of sound, V is the internal volume of the resonance box 17, and G is the conductivity of the sound in the hole 15 (Condu).
activity). If the number of holes 15 communicating with the resonator 17 is one and the hole 15 is circular, G
Is given by the following equation (4).

[0024]

(Equation 4)

Here, S is the opening area of the hole 15 and l is the hole 1
The length (depth) of 5 and a is the radius of the hole 15. Here, by making the resonance frequency fr of the resonator 17 coincide with, for example, the frequency of the main noise in the carrier frequency band of the inverter control, the noise can be reduced efficiently. For example, when the operation of the motor generates noise mainly at the carrier frequency of the inverter control, and the fundamental frequency of the noise is 1000 Hz, the internal volume V and the like are set so that the resonance frequency of the resonator 17 also becomes 1000 Hz. When the sound wave of this frequency propagates through the motor frame 2 and reaches the resonator 17, the sound wave and the air in the resonator 17 resonate with each other, so that the hole 1
Five parts of air vibrate violently. As a result, sound energy is mainly converted to thermal energy due to friction, and noise in a frequency band near 1000 Hz is effectively reduced.

FIG. 4 shows a third embodiment of the present invention. Reference numeral 18 denotes an interfering body, in which a first passage 18a and a second passage 18b which bypasses the first passage 18a are provided. The second passage 18b is bent in a U-shape, branches from the entrance of the first passage 18a, and communicates with the exit. In this case, the lengths L1 and L2 from the branch point A to the junction B of the first and second passages 18a and 18b are set as follows.

Assuming that the wavelength of the sound wave of a predetermined frequency generated from the motor section 1 is λ, L2−L1 = (λ / 2) × NN = 1,2,3,... , L2,
The difference is set to be a length obtained by multiplying the half wavelength (λ / 2) by an integer. In this example, 10000H
z, and when the sound speed is 340 m / s, the wavelength λ becomes 9.4 cm. Therefore, L1 is set to λ / 4
Is set to 2.35 cm, and L2 is set to 7.05 cm, which is equivalent to λ × 3/4.
L1 = λ / 2. Alternatively, L1 is set to 4.7 cm corresponding to λ / 2, and L2 is set to 9.4 corresponding to λ.
cm.

According to this configuration, the sound waves generated by the motor unit 1 are once separated and propagated into the first passage 18a and the second passage 18b, and then superimposed at the junction of the two passages. In this case, since the lengths of both passages are different by a length obtained by multiplying the half wavelength λ / 2 of the sound wave by an integer, the sound wave from the first passage 18a and the sound wave from the second passage 18b are mutually different. The sound waves are canceled out because they are superimposed in opposite phases, thereby attenuating noise.

A fourth embodiment of the present invention will be described with reference to FIG. The following relationship exists between the frequency f of the noise generated from the motor unit 1 and the wavelength λ of the sound wave.

Λ = c / fc = sound speed Here, the length dimensions Lx, Ly, Lz of the three sides of the control case 9 shown in FIG. 5 (b) are half wavelengths of the frequency of the noise generated from the motor unit 1. It is set so that it does not coincide with λ / 2 or an integral multiple or 1 / integer multiple of half wavelength λ / 2.

That is, Lx ≠ (λ / 2) × NN = 1, 2, 3,..., 1/2, 1/3, Ly (λ / 2) × NN = 1, 2, 3,. Ly ≠ (λ / 2) × N N = 1, 2, 3,... 1/2, 1/3,... In the internal space of the control case 9, a natural frequency (a kind of reverberation) ), And there is a characteristic that only a certain number of frequencies sound well. Therefore, only some frequency components are emphasized by the natural frequency and sound well.

For example, if the motor generated noise frequency is 1000
In the case of 0 Hz, the wavelength λ is λ = 340/10000 = 3.4 cm, the half wavelength λ / 2 is 1.7 cm, and λ / 4 is 0.85.
Since cm and λ / 8 are 0.425 cm, Lx and L shown in the schematic explanatory view of FIG.
Set y and Lz. Here, the natural frequency fn of the space inside the motor frame 2 and the space inside the control case 9 is expressed by the following equation (5), where the sound speed in the air is c.

[0033]

(Equation 5)

(Refer to “Practical Vibration Calculation Method” (published by Kogaku Tosho Co., Ltd.), page 214) where Lx, Ly, and Lz are the lengths of three sides in the control case, and Nx, NY, and Nz are 0 or any arbitrary value. It is a positive integer and there is one eigenmode for a set of Nx, NY, Nz.

Here, L is set so that it does not coincide with an integral multiple or 1 / integer multiple of a half wavelength of a sound wave generated from the motor unit 1.
Since x, Ly and Lz are set, the radiation noise from the control case 9 is reduced.

Although the setting of the outer dimensions of the control case 9 has been described above, for example, in the small space U in the control case 9, another natural frequency exists, and this small space U
In this case, the harmonic components of the noise have an effect. Therefore, in the small space U, the small space U
If the dimensions lx, ly, lz are set, the noise can be reduced more effectively.

FIGS. 6 and 7 show a fifth embodiment of the present invention. The motor frame 2 and the control case 9 are provided with cooling fins 19, 20, and 21, respectively. Is represented by

[0038]

(Equation 6)

Here, D, l, and b are set so that the wavelength of the frequency of the noise generated from the motor unit 1 or its integral multiple does not match the natural frequency of the cooling fin. The radiation noise to the outside is reduced.

The following relationship exists between the frequency f of the noise generated from the motor unit 1 and the wavelength λ of the sound wave. λ = c / fc = sound speed Here, as shown in FIG. 6 and FIG.
The interval K between 0 and 21 is set so as not to coincide with a half wavelength λ / 2 of the frequency of the noise generated from the motor unit 1 or an integral multiple or 1 / integer multiple of the half wavelength λ / 2.

That is, there is a natural frequency (a kind of reverberation) in the space between the cooling fins, and there is a characteristic that only sounds of certain specific frequencies resonate well. Therefore, only some frequency components are emphasized by the natural frequency and sound well.

Therefore, for example, when the motor-generated noise frequency is 10000 Hz, the wavelength λ is λ = 340/10000 = 3.4 cm, the half wavelength λ / 2 is 1.7 cm, and λ / 4 is 0.85.
Since cm and λ / 8 are 0.425 cm, noise can be effectively reduced by setting the interval between the cooling fins so as to avoid these dimensions.

[0043]

As apparent from the above description, according to the motor with the control unit according to the first aspect, the noise generated from the motor can be effectively reduced.
According to the motor with the control unit according to the second aspect, the noise generated from the motor unit can be effectively reduced, and it is not necessary to provide another muffler, and the control case serving as the cover of the inverter device can be effectively used. It is.

According to the motor with the control unit according to the third aspect, the noise generated from the motor section can be effectively reduced as in the first aspect of the invention. According to the motor with the control unit according to the fourth aspect, the sound wave from the first passage and the sound wave from the second passage are superimposed on each other in a state opposite to each other, so that the sound wave is canceled out, thereby attenuating noise. Things.

According to the motor with the control unit according to the fifth aspect, sound waves of a predetermined frequency generated from the motor unit can be effectively reduced. According to the motor with the control unit according to the sixth aspect, since the natural frequencies do not match, radiation noise to the outside of the case is reduced. According to the motor with the control unit according to claim 7,
Sound waves generated from the motor unit can be effectively reduced.

[Brief description of the drawings]

FIG. 1 is a cross-sectional plan view showing a first embodiment of the present invention;

FIG. 2 is a diagram showing a noise level according to the related art and the present invention;

FIG. 3 is a cross-sectional plan view showing a second embodiment of the present invention;

FIG. 4 is a cross-sectional plan view showing a third embodiment of the present invention;

FIG. 5 is a cross-sectional plan view showing a fourth embodiment of the present invention;

FIG. 6 is a plan view showing fifth and sixth embodiments of the present invention;

FIG. 7 is an explanatory view of a cooling fin,

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Motor part, 2 ... Motor frame, 2b, 2c ... Bearing bracket, 3 ... Stator, 7 ... Rotor, 8 ... Control unit, 9 ... Control case, 10 ... Inverter device, 14 ... Space, 15 ... Hole, 16 ... silencer, 17 ... resonator, 18 ... interference body, 19, 20, 21 ... cooling fins.

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Shiyasu Mochizuki 2121 Ryousei, Asahi-cho, Mie-gun, Mie Prefecture F-term in Toshiba Mie Plant (reference) 5H605 AA01 AA05 BB05 CC01 CC02 DD07 DD23 5H607 AA03 AA04 AA12 BB01 BB14 CC01 DD01 DD02 DD08 DD09 DD16

Claims (7)

[Claims] A control unit having a motor unit having a stator and a rotor in a motor frame, a control unit having an inverter device provided in a control case, and a bearing bracket being provided between the motor frame and the control case. A motor with a control unit, wherein a silencer for attenuating a predetermined frequency of a sound wave generated from the motor unit is provided in a control case. 2. The motor with a control unit according to claim 1, wherein the muffler comprises a hole provided in the bearing bracket and a space in the control case. 3. A control unit having a motor unit having a stator and a rotor in a motor frame, a control unit provided with an inverter device in a control case, and a bearing bracket provided between the motor frame and the control case. A motor with a control unit, wherein a resonance body for resonating sound waves generated from the motor unit is provided in a control case. 4. A control unit having a motor unit having a stator and a rotor in a motor frame, a control unit having an inverter device provided in a control case, and a bearing bracket being provided between the motor frame and the control case. Motor with a first passage and a first passage in the control case.
And an interfering body having a second passage detouring the path of the second path, wherein the length of the second path is made an integral multiple of the length of the first path by a half wavelength of a sound wave of a predetermined frequency generated from the motor section. A motor with a control unit, characterized in that the length differs. 5. A control unit having a motor unit having a stator and a rotor in a motor frame, a control unit provided with an inverter device in a control case, and a bearing bracket provided between the motor frame and the control case. A motor with a control unit, wherein three sides of the control case have a length that does not coincide with a wavelength of a sound wave of a predetermined frequency generated from the motor unit. 6. A motor with a control unit, wherein cooling fins are provided on a motor frame and a control case, and a natural frequency of these cooling fins and a predetermined frequency of a sound wave generated from the motor unit are not made to coincide with each other. 7. A control characterized in that cooling fins are provided on a motor case and a control case, and the interval between the cooling fins is set so that the wavelength of a sound wave generated from the motor unit does not coincide with the natural frequency of the cooling fins. Motor with unit.