JP3584019B2 - Refrigerant compressor - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a refrigerant compressor, and more particularly to a refrigerant compressor capable of supporting a new refrigerant (a single HFC-based refrigerant or a mixed refrigerant thereof).
[0002]
[Prior art]
As the refrigerant for compressors such as air conditioners, CFC-based and HCFC-based CFCs, which have been used conventionally, cause destruction of the ozone layer. Various new refrigerants such as HFCs have been proposed as candidates. In addition, the voltage control of the drive power supply of a DC brushless motor for driving a compressor such as an air conditioner has shifted from the conventional PWM (pulse width modulation) control method to a PAM (pulse amplitude modulation) control method capable of reducing loss. ing.
[0003]
Even when a new refrigerant is used for the refrigerant compressor, it is necessary to suppress the leakage current of the electric motor within a specified value (for example, 1.0 mA). However, a combination of an HFC-based refrigerant and an ether-based or ester-based lubricating oil is used. In this case, the leakage current tends to increase as compared with the conventional case.
[0004]
In addition, the insulation paper used for the stator of the motor is attacked by some new refrigerants, and the insulation performance is reduced. The dielectric constant increases, the capacitance of the insulation paper increases, the leakage current increases, and the power loss increases. Was the cause.
[0005]
[Problems to be solved by the invention]
Therefore, the present invention has been made in view of the above problems, and uses a new refrigerant that is a combination of an HFC-based refrigerant and an ether-based or ester-based lubricant, and has a large BH product in the magnet material of the rotor of the DC brushless motor. To reduce the stacking height of the core, reduce the volume of the stator winding, and thus the amount of copper wire used, to reduce the copper loss, iron loss and impedance of the copper wire, An object of the present invention is to provide a refrigerant compressor that suppresses leakage current by reducing the capacitance by using an insulating film having a small dielectric constant.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, a refrigerant compressor according to claim 1 of the present invention encloses a compression element and a DC brushless motor that drives the compression element in an airtight container, and has a single HFC-based refrigerant or A refrigerant compressor in which the mixed refrigerant and an ether-based or ester-based lubricating oil are sealed in the closed container, wherein the DC brushless electric motor has a three-phase stator winding on a PEN film of the stator. And a composite product of PPS film or aramid paper or a combination of these and PET film, and a four-pole rare earth magnet is inserted into the rotor core and an inverter is connected to the three-phase stator winding. Power is supplied via a circuit.
[0007]
Thus, the DC brushless motor for a compressor according to the present invention can use a HFC-based refrigerant such as R410A or R407C and an ether-based or ester-based lubricating oil as a new refrigerant, as compared with a normal ferrite magnet as a rotor magnet. Although the price per unit weight is expensive, the BH product is extremely large. By using rare earth magnets such as neodymium and boron, the stack height of the core can be reduced, and the volume of the stator winding can be reduced. That is, the loss of the motor can be reduced by reducing the amount of copper wire used.
[0008]
At the same time, the use of PEN film, PPS film or composite paper of aramid paper or a combination of these and PET film as insulating paper, etc., reduces the relative dielectric constant, reduces the capacitance, and reduces the impedance of the motor. This makes it possible to reduce the loss of the motor.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described below. FIG. 1 is a principle block diagram of a drive circuit of a commonly used DC brushless motor for a compressor. In the figure, 1 is a DC power supply obtained by rectifying an AC power supply, 2 is a permanent magnet rotor, 3 is an inverter circuit that supplies power to a stator winding to generate a rotating magnetic field in a stator 4, and 6 is an inverter circuit. Rotor position detecting means for detecting a rotational position of the rotor based on a comparison between a terminal voltage of the stator winding and a neutral point voltage. In the inverter circuit 3, six transistors Tr1 to Tr6 are connected in a three-phase bridge.
[0010]
The control circuit 5 is a control circuit that outputs a signal for controlling the energization of the transistors Tr1 to Tr6 constituting such an inverter 3 in a predetermined combination, and the permanent magnet (2) detected by the rotor position detecting means 6 Pole) The combination of energization to the stator windings is switched in a predetermined order in accordance with the rotational position of the rotor to maintain the rotation of the rotor. The rotation speed of the rotor is controlled by changing the voltage of the DC power output from the DC power supply 1.
[0011]
FIG. 2 shows an embodiment of the refrigerant compressor of the present invention. FIG. 2 is a longitudinal sectional view of the refrigerant compressor, in which 21 is a stator core of the electric motor, 22 is a three-phase stator winding fixed to and inserted into the core 21, 23 is a coil end of the stator winding, 24 is a rotor shaft to which the rotor is fixed, 25 is a cup fixed to the compressor, 26 is a cylinder block of a compressor (not shown), and 27 is a storage case of the compressor.
[0012]
FIG. 3 is a cross-sectional view of the electric motor, and the same components as those in FIG. 2 are denoted by the same reference numerals. The stator winding 22 is a three-phase winding of A phase, B phase, and C phase. The windings of the respective layers are respectively wound (distributed winding) of an intermediate magnetic pole system called an image pole system, and are wound in two layers: an L coil having a long winding width and an M coil having a short winding width.
[0013]
Four plate-shaped rare earth magnets 28 made of neodymium or the like are arranged in the iron core of the rotor 2. The plate-shaped rare earth magnet 28 has a stronger magnetic force than a normal ferrite magnet, and uses magnet materials that are not subjected to corner chamfering and surface treatment as they are, thereby facilitating manufacturing and managing the magnet materials. ing.
[0014]
In the DC brushless motor for a compressor having such a configuration, as a new refrigerant replacing the conventional refrigerant, as a result of experiments, the present applicant has effectively used an HFC-based refrigerant and an ether-based or ester-based lubricating oil. Was found. In particular, polyol ester oil for R134a, polyvinyl ether oil for R410A or R407C, and either polyol ester oil or polyvinyl ester oil for R404A are preferable. On the other hand, it was also found that this new refrigerant tends to increase the leakage current of the compression motor.
[0015]
In the present invention, HFC-based refrigerants such as R410A and R407C and ether-based or ester-based lubricating oil are used as new refrigerants. However, the leakage current depends on the volume of the motor (the length of the stator winding). Although the price per unit weight is higher than that of a normal ferrite magnet, the BH product is a rare-earth magnet made of neodymium, boron, etc. The thickness direction is reduced, and the stack thickness of the stator is reduced accordingly. As a result, the volume (length) of the stator winding is reduced, and the leakage current from the stator winding is reduced accordingly. be able to.
[0016]
That is, by reducing the volume of the stator windings, it is possible to reduce the leakage current more than the leakage current increased by using the new refrigerant.
[0017]
Further, in the present invention, as described above, the stator winding of the electric motor is a winding of an intermediate magnetic pole (image pole) type. Next, the image pole type winding of the stator winding will be briefly described with reference to FIGS. FIG. 4 shows an image pole system in which two poles form four poles (abbreviated as IP in the figure), an image pole system in which three poles form six poles, and an image pole system in which four poles form eight poles. FIG. 4 shows a diagram illustrating an example symbolically.
[0018]
For example, an image pole system in which four poles are formed by two poles will be described. The A-phase long stator winding 22L and the short winding width stator winding 22M wound around the opposing position in FIG. And the same poles N collide with each other. As a result, another pole S is virtually generated in the direction perpendicular to the poles, and four poles are formed by two stator windings. is there.
[0019]
As a result, the leakage current of the motor tends to increase in proportion to the surface area of the winding, so that in the image pole method, the stator winding becomes half the desired number of poles, and the amount of copper wire used can be reduced, so that the winding is reduced. The leakage current can be reduced by reducing the number and amount of wires, and as a result, the leakage current can be suppressed within a specified value.
[0020]
Further, the insulating paper in the winding groove of the electric motor is attacked by the HFC-based refrigerant such as R410A and R407C and the new refrigerant using the ether-based or ester-based lubricating oil, thereby deteriorating the insulation and reducing the insulation effect. In addition, the relative dielectric constant is increased to cause an increase in capacitance, which is a cause of an increase in leakage current (loss).
[0021]
Therefore, in order to solve this problem, a PEN (polyethylene naphthalate) film, a PPS (polyphenylene sulfide) film or a composite product of aramid paper or a combination thereof with a PET (polyethylene terephthalate) film is used as insulating paper for a motor. As the wire slot insulating paper or wedge insulating paper, a material other than the PET film was mainly used.
[0022]
That is, for example, a PEN film, a PPS film, or a composite of aramid paper having a relative dielectric constant of less than 3.1 at 25 ° C. and 1 KHz or a combination thereof with a PET film is used for the groove insulating paper of the winding. By mainly using a non-PET film as the slot insulating paper or wedge insulating paper, the use of insulating paper having a small relative dielectric constant can reduce the capacitance and suppress the leakage current.
[0023]
【The invention's effect】
As described above, the present invention relates to a refrigerant compressor using a DC brushless motor driven by an inverter using a new refrigerant obtained by combining an HFC-based refrigerant such as R410A and R407C with an ether-based or ester-based lubricant. By employing a rare earth magnet as the magnet material of the rotor, the core lamination height is reduced, the volume of the motor and the amount of copper wire used are reduced, and the leakage current can be suppressed within a specified value.
[0024]
In addition, the leakage current can be suppressed within a specified value by reducing the capacitance by using insulating paper having a small relative dielectric constant.
[Brief description of the drawings]
FIG. 1 is a block diagram of a drive circuit of a DC brushless motor for a compressor.
FIG. 2 is a layout diagram of a refrigerant compressor.
FIG. 3 is a sectional view of a DC brushless motor for a compressor according to the present invention.
FIG. 4 is an explanatory diagram of a symbolic image pole system.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 DC power supply 2 Permanent magnet rotor 3 Inverter circuit 4 Stator 5 Control circuit 6 Rotor position detecting means 21 Stator core 22 Stator winding 23 Coil end 24 Rotor shaft 25 Cup 26 Cylinder block 27 Storage case 28 Flat Rare earth magnet

Claims (1)

In addition to enclosing a compression element and a DC brushless motor that drives the compression element in a closed container, a single HFC-based refrigerant or a mixed refrigerant thereof, and an ether-based or ester-based lubricating oil are sealed in the closed container. The DC brushless motor comprises a three-phase stator winding formed on a stator thereof by using a composite product of a PEN film, a PPS film or an aramid paper, or a combination of these and a PET film. A refrigerant compressor, wherein a four-pole rare earth magnet is inserted into the rotor core and power is supplied to the three-phase stator windings via an inverter circuit.

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