JPS6359030B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION An object of the present invention is to reduce the size and weight of a compressor that rotates at a higher speed than the rotation speed obtained at the commercial power frequency, and particularly to reduce vibration by increasing the resonance frequency of the rotating shaft.

In the past, compressors have been proposed that have a power frequency higher than the commercial power frequency, making them faster, smaller, and lighter. There was no attempt to reduce the vibrations of the compressor itself.
As a result, when the electric compressor is rotated at high speed,
Abnormal vibrations occurred, resulting in extremely high levels of noise. That is, conventional electric compressors generally employ a two-pole motor, and as shown in FIG. It consists of a compressor section that contracts and compresses, and an electric motor section consisting of a rotor 6 and a stator 7 connected to the rotating shaft 4, and the rotor 6
is cantilevered by the upper bearing 2 of the compressor section. The stator 7 has a coil end 8, which is provided in the space between the stator 7 and the upper bearing 2. However, since it is a two-pole motor, the coil of the stator 7 has a maximum semicircular circumference at the coil end. As a result, the coil end becomes high, forcing a large distance from the upper bearing 2 to the stator 7. As a result, the center of gravity of the rotor 6 relative to the rotating shaft 4 becomes If the position is M and the apparent fulcrum of the rotating shaft 4 is P, then the above center of gravity M and the fulcrum P
As the distance between them increases, the resonant frequency F of the rotary shaft 4 becomes lower, and if this electric compressor is rotated at high speed, the rotary frequency approaches this resonant frequency F, and the rotary shaft 4 becomes in a resonant state, causing vibrations and The noise increased, and in the worst case, there was a risk that the rotating shaft 4 would be damaged.

The present invention is intended to improve these drawbacks, and will be described below with reference to FIGS. 2 and 3, which show one embodiment of the present invention.

That is, a piston 14 that rotates around a rotating shaft 13 is provided in a space surrounded by a cylinder 10, an upper bearing 11, and a lower bearing 12, sucks refrigerant gas through a suction pipe 15, compresses the refrigerant gas with the piston 14, and discharges the piston 14. Compressor section A that discharges from valve 16
The compressor section A is composed of a rotor 17 and a stator 18 connected by a rotating shaft 13, and has an electric motor section B that drives the compressor section A. is provided in the sealed housing 19 and constitutes an electric compressor C. The rotating shaft 13 is cantilevered by the upper bearing 11. On the other hand, the motor section B is composed of a four-pole induction motor, and includes the coil end 2 of the stator 18.
0 height is smaller than that of conventional two-pole motors. As a result, the space between the upper bearing 11 and the stator 18 can be reduced, and the space between the upper bearing 11 and the stator 18 can be reduced.
8 can be brought close to each other, and the distance between the center of gravity m of the rotor 17 with respect to the rotation shaft 13 and the apparent fulcrum p of the rotation shaft 13 can be reduced, and as a result, the resonance frequency of the rotation shaft 13 can be reduced. F ₀ can be increased. That is, the resonant frequency
Roughly speaking, if the diameter of the rotating shaft and the weight of the rotor are the same, F ₀ is inversely proportional to the 3/2 power of the distance between the center of gravity m and the fulcrum p, so the frequency is much higher than that of conventional electric compressors. It can be done. As a result, even when the electric compressor is driven at high speed, the resonance frequency can be set to a value sufficiently high relative to the rotational frequency, and an electric compressor with low vibration and noise can be provided.
Further, the electric compressor section A and the electric motor section B can be provided close to each other, and the electric compressor C can be made low in height. Furthermore, the fact that the height of the coil end 20 is low means that the length of the copper wire used is short, which reduces copper loss in the motor section B and increases efficiency. 21 is a terminal provided in the sealed housing 19, which connects the power source to the electric motor section B.
It is provided to supply the stator 18 of.

That is, the power supply section of the electric compressor C uses a three-phase commercial power supply (this may be a single phase) 22 as a primary power supply, and six diodes D ₁ , D ₂ , D ₃ , D ₄ , D ₅ ,
It is rectified by a rectifier circuit D consisting of a capacitor _C1 , a chopper coil CH _{1 ,} and a capacitor C1.
Tr ₁ is driven to control the voltage of the DC power supply, and the voltage is smoothed by a chiyoke coil CH ₂ and a capacitor C ₂ . This adjusted and smoothed DC power supply is input to the bridge inverter control circuit H to generate a frequency corresponding to the DC voltage, and the transistors Tr ₂ and Tr ₃ of the bridge inverter circuit I connected to the chopper circuit G are connected to the bridge inverter control circuit H. , Tr ₄ , Tr ₅ , Tr ₆ , and Tr ₇ to generate a three-phase rectangular wave power source with a frequency more than twice as high as the commercial power frequency, and supply power to the motor section B via the terminal 21. In addition, each transistor
Diodes D ₇ , D ₈ , D ₉ , D ₁₀ , D ₁₁ , _{and D 12 are} connected in parallel with Tr ₂ , Tr ₃ , Tr ₄ , Tr ₅ , Tr ₆ , and _{Tr 7 .} This is for passing the back electromotive force of the motor section B when it is turned off, and serves to protect each of the transistors Tr ₂ to _{Tr 7} .

The motor section B of the electric compressor of the present invention shown in FIG. 2 is a four-pole induction motor, but if it is a six-pole induction motor, the height of the coil end 20 can be further reduced. However, the rate of decrease is not very large. On the other hand, in order to achieve the same rotation speed as the electric compressor of the present invention, the electric motor part B
The frequency of the power supply must be increased by 3/2. As a result, the bridge inverter circuit I
Transistors Tr ₂ , Tr ₃ , Tr ₄ , Tr ₅ , Tr ₆ , Tr ₇
As the number of ON-OFF turns increases, the transistor
Power loss due to ON-OFF will increase. As a result, the efficiency of the power supply section decreases, leading to an increase in the primary power input. This value becomes larger as the number of poles of the motor increases. From the above, it is possible to increase the resonant frequency of the rotating shaft to a level that poses no practical problems by making the motor of the electric compressor four poles and increasing the frequency of the power applied to it to be more than twice that of the commercial power supply. As soon as possible,
This is the optimal combination that can be used without reducing the efficiency of the power supply section.

As is clear from the above embodiments, the electric compressor of the present invention includes a compressor section that sucks in gas, increases the pressure, and discharges the gas, and a compressor section that is connected to the compressor section by a rotating shaft and that is attached to a bearing of the compressor section. The coil end of the stator of the four-pole motor has a four-pole motor section having a supported rotor, and a power supply section that supplies power at a frequency that is twice or more higher than the commercial power frequency to the four-pole motor section. is as low as possible, and the stator is located as close as possible to the bearing section. By using the four-pole motor, the dimensions of the coil end section can be reduced and the resonance of the rotating shaft of the compressor section can be reduced. It is possible to increase the frequency to a level that does not cause any practical problems, and it is the optimal combination of the motor and power supply that can be used without reducing the efficiency of the power supply. Loss can be reduced and efficiency can be increased. As a result, it is possible to provide a small electric compressor with low vibration and noise.

[Brief explanation of drawings]

Fig. 1 is a longitudinal sectional view of a conventional electric compressor, Fig. 2 is a longitudinal sectional view of an electric compressor showing an embodiment of the present invention, and Fig. 3 is a circuit diagram of the power supply section of the electric compressor. . A... Compressor section, B... Electric motor section, C... Electric compressor, 10... Cylinder, 13... Rotating shaft, 1
4... Piston, 17... Rotor, 18... Stator, 20... Coil end.

Claims (1)

[Claims] 1. A compressor section that sucks in gas, raises the pressure, and discharges it; a 4-pole electric motor section that is connected to this compressor section by a rotating shaft and has a rotor that is cantilever-supported by a bearing of the compressor section; and a power supply section that supplies power at a frequency that is at least twice as high as the commercial power supply frequency to the pole motor section, and the coil end of the stator of the four-pole motor is set as low as possible, and the rotor is set as low as possible. An electric compressor installed near the bearing.