JPH0749888B2 - heat pump - Google Patents

Description

TECHNICAL FIELD The present invention relates to a heat pump using a centrifugal compressor driven by an electric motor for cooling a refrigerant, and particularly to dichlorotrifluoroethane (hereinafter referred to as R-) as a refrigerant. (Referred to as 123) can be used for a heat pump using a centrifugal compressor driven by an electric motor.

[Conventional technology]

Conventionally, as a kind of heat pump, it is composed of a centrifugal compressor driven by an electric motor, a condenser, a pressure reducing device, an evaporator, and a piping path connecting these devices, and is the same as the refrigerant circulating in these devices. There is a heat pump in which the electric motor is cooled by the refrigerant, but in this foot pump, trichloromonofluoromethane (hereinafter referred to as R-11) is used as the refrigerant.

[Problems to be Solved by the Invention]

However, this R-11 has a problem that it destroys the ozone layer in the stratosphere, and its regulation is being made worldwide.

Although R-123 is being researched as a candidate for the alternative refrigerant, this refrigerant has a strong dissolving action and a swelling action on the organic insulating material of the electric wire of the electric motor, which causes a large dielectric breakdown accident of the electric motor winding. Since it has a defect, it cannot be used for a heat pump driven by an electric motor for cooling a refrigerant.

[Means for Solving the Problems]

The present invention is composed of a centrifugal compressor driven by an electric motor, a condenser, a decompression device, an evaporator, and a pipe path connecting these devices, and the same refrigerant as the refrigerant circulating in these devices is used. In a heat pump in which an electric motor is cooled, R-123 is used as the refrigerant, and a temperature control device that directly or indirectly detects the temperature of the electric motor coil portion and sets the temperature to 120 ° C. or less is provided. Then
In addition, the above problem has been solved by a heat pump characterized in that the motor winding is a polyimide wire.

By configuring the heat pump as described above, it is possible to provide a heat pump having a long life even if R-123, which hardly destroys the stratospheric ozone layer, is used.

In this heat pump, the refrigerant is cooled by directly contacting the coil portion of the electric motor, so that the cooling efficiency is good.

Here, the heat pump includes not only a heat pump in a narrow sense for producing a warm fluid but also a refrigerator for producing a cold fluid.

The polyimide wire in the present invention refers to a copper wire covered with a polyimide layer, and may or may not have a coating layer of other synthetic resin or the like in the middle. Further, the polyimide layer may be further coated with another coating layer such as polyester.

[Work]

Since the polyimide wire of the motor winding in the present invention hardly melts or swells with R-123, even if the motor winding is cooled by directly contacting with R-123, a dielectric breakdown accident will occur. It never happens. However, since the polyimide wire becomes soluble and swellable with respect to R-123 when the temperature exceeds 130 ° C, it is necessary to keep the temperature of the coil below 120 ° C so that the temperature of the winding does not exceed 120 ° C in practice. is there.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. However, this embodiment is merely an example of the embodiment of the present invention, and examples having the technical idea of the present invention are included in the present invention.

FIG. 1 is a diagram showing a schematic configuration of a heat pump according to the present invention. In the figure, 1 is a centrifugal compressor, 2 is a condenser, 3 is a decompression device, and 4 is an evaporator. These centrifugal compressor 1, condenser 2, decompression device 3 and evaporator 4 are connected by a refrigerant path to form a refrigerant circulation flow path.

In the heat pump configured as described above, the refrigerant gas compressed by the compressor 1 is cooled and condensed by the load fluid sent from the flow path 5 in the condenser 2 and decompressed by the decompression device 3, and then the evaporator. Up to 4. The evaporator 4 is heated and evaporated by the heat source fluid sent from the flow path 6 and returns to the centrifugal compressor 1 again to form a heat pump cycle. On the other hand, the load fluid flowing through the flow path 5 is heated by the condenser 2,
It is supplied to a load (not shown). In this heat pump, R-123 is used as the refrigerant.

Further, a part of the R-123 liquid condensed in the condenser is sent to the electric motor 8 by the refrigerant pump 7, cools the winding 9 of the electric motor, and the refrigerant itself is heated and evaporated. Then, it returns to the condenser 2 again.

A polyimide wire is used for the winding 9.
A temperature detector 10 is attached to the surface of the winding. This temperature signal is sent to the controller 11, but the temperature rises
When it reaches 120 ° C, measures are taken to reduce the winding temperature of the motor. For example, the load of the compressor, that is, the load of the electric motor 8 is reduced by operating the motor 13 that drives the suction vane control device 12, which is the capacity control device of the centrifugal compressor 1. Further, as a measure for decreasing the winding temperature of the electric motor, the operation of the electric motor may be stopped. As a result, the coil of the electric motor is kept at 120 ° C or lower.

With the above configuration, the heat pump of the present invention could be efficiently operated for a long period of time.

As described above, the present invention, the motor winding is a polyimide wire, the maximum operating temperature is controlled to be suppressed to 120 ℃,
By satisfying all three conditions that R-123 is used as a refrigerant, a heat pump using an electric motor cooled by a refrigerant that does not adversely affect the stratospheric ozone layer is realized. This is because the conditions under which R-123 can be used for a long period of time in order to set the two conditions are sought, and the material of the winding wire of the electric motor is deeply examined.

According to the research results, the polyimide wire can sufficiently withstand R-123, and its practical resistance can be judged by looking at the dielectric breakdown voltage at each temperature. FIG. 2 shows the dielectric breakdown voltage of the polyimide wire at each temperature in the R-123 atmosphere, the vertical axis represents the dielectric breakdown voltage, and the horizontal axis represents the atmospheric temperature.

As shown in the figure, this winding does not lower the dielectric breakdown voltage up to about 120 ° C, but it rapidly deteriorates at higher temperatures.
This phenomenon was unexpected for a person skilled in the art.

〔The invention's effect〕

Since the heat pump of the present invention is configured as described above, it has the following excellent effects.

(1) The heat pump can be operated using R-123 as the refrigerant. And, even if it leaks, it hardly destroys the stratospheric ozone layer.

(2) The motor coil does not deteriorate.

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic structure of a heat pump according to the present invention, and FIG. 2 shows a dielectric breakdown voltage of a polyimide wire in an R-123 atmosphere at various temperatures. 1 ... Centrifugal compressor, 2 ... Condenser, 3 ... Pressure reducing device,
4 ... Evaporator, 7 ... Refrigerant pump, 8 ... Electric motor, 9 ...
… Winding

Claims (1)

[Claims] Claims: 1. A centrifugal compressor driven by an electric motor, a condenser, a decompression device, an evaporator, a piping path connecting these devices, and the like, and the same refrigerant that circulates in these devices. In the heat pump adapted to cool the electric motor, dichlorotrifluoroethane is used as the refrigerant, and the temperature of the electric motor coil portion is directly or indirectly detected, and the temperature control device is 120 ° C. or lower. And a heat pump characterized in that the motor winding is a polyimide wire.