JPS6071859A - Heat pump - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heat pump having an electric motor that is cooled with a refrigerant.

In this specification, "heat pump" refers not only to heat pumps in a narrow sense that produce hot fluids, but also to heat pumps in a broad sense that includes refrigerators that produce cold fluids.

Furthermore, in this specification, the high-pressure gas flow path inside the condenser itself is also referred to as a "high-pressure gas flow path," including the high-pressure gas flow path outside the condenser.

Conventionally, two types of cooling methods have been used to cool the motor of a hermetic centrifugal refrigerator or the like: a refrigerant liquid cooling method and a refrigerant gas cooling method.

The refrigerant liquid cooling method is a method in which condensed liquid is fed into the motor maintained at approximately the evaporation pressure, evaporated under reduced pressure, and the motor is cooled by the latent heat of evaporation. This method has the disadvantage that the capacity of the evaporator is reduced by the amount of heat used to cool the motor, resulting in a lower buildup coefficient. Furthermore, in the conventional refrigerant gas cooling system, the gas in the condenser is sucked in by a motor-driven fan built into the motor, the refrigerant is cooled by gas, and then returned to the condenser. However, this method has the disadvantage that it is necessary to incorporate a fan inside the motor, making the structure of the motor very complicated.

An object of the present invention is to provide a heat pump having a refrigerant gas-cooled motor cooling method that does not require a complicated motor structure.

2- The present invention comprises an evaporator, a multi-stage compressor, a plurality of condensers,
a plurality of expansion devices, the plurality of condensers are arranged to be sequentially cooled in series by the fluid to be heated, the compressor is driven by an electric motor, and the cooling of the motor is provided downstream of the fluid to be heated; This heat pump is characterized in that the refrigerant gas that has cooled the motor is introduced into the high-pressure gas flow path upstream of the fluid to be heated.

The present invention will be explained with reference to the drawings based on examples.

Figure 1 shows a 70-sheet pump with four sets of condensers, four compressor impellers, and one pump.

There is only one evaporator 1, and it is heated by the heat source water that is sent up to the pipe 2, and the evaporated refrigerant gas is passed through the suction pipe 3 → suction header 4 → suction pipes 5.5', 5''.

5″ to the impellers of each stage of compression Wi6 7.7′, 7″.

The gas compressed by the compressor 6 is discharged into four condensers 8, 8', 8' and 8'. This condenser is cooled by a load fluid as a fluid to be heated. The load fluid is heated by the pump 9 as it flows through these four condensers in series.

Usually, the load fluid of this system is a load fluid with a large difference in temperature between the inlet and outlet, such as hot water supply or drying air. For example, if the water supplied from the load fluid outlet 10 is about 20°C, the temperature will be 10°C in each condenser.
The temperature at the load fluid outlet 11 reaches about 60° C. and is used for loading.

Conversely, the refrigerant gas is cooled and condensed, and the pipe 12° + 2'
, + 2″, 12″, expansion device 13° 13′
, +3", +3" and sent to the evaporator.

As mentioned above, since the temperature difference between the inlet and outlet of the load fluid is enormous, the condensation temperatures of the four condensers are different.

For example, in the case of the water heater mentioned above, the condensing temperature is approximately 3
5°C, 45°C, 55°C, and 65°C. Therefore, when the evaporation temperature is 15°C, the impeller 7 is
The pressure may be increased to a pressure equivalent to 5°C. Impeller 7″ is 1
It is necessary to raise the pressure from the pressure equivalent to 5°C to the pressure equivalent to 65°C.

To give an example 4--, cooling of the motor of the pump of this embodiment is carried out as follows. In other words, the refrigerant gas in the highest pressure condenser 8'', which is the most downstream of the load fluid, is transferred to the pipe 14.
The load fluid is guided to the motor 15, cools the stator 16 and rotor 17 inside the motor, and passes through the piping 18 to the condenser 8'' on the upstream side of the load fluid, which has a lower pressure than 8''.
will be introduced in

In this example, the gas flow is 8 IN→8'', but it may be 8''→8' or 8'→8, or if the pressure difference is small, 8''→8', 8''→8 It is also possible to set B′′→8. That is, the load fluid is caused to flow from the downstream condenser to the upstream condenser.

The refrigerant gas may be taken out from inside the condenser 8'', 8'', B itself or from a gas passage outside the condenser. The refrigerant gas is returned to condensers 8″ and 8′.

The high pressure on the downstream side of the load fluid is taken out from the gas flow path, cools the motor, and is returned to the high pressure gas flow path on the upstream side of the load fluid. do.

Although four condensers are shown in this example, it is not possible to partition the inside of the condenser 5-- into four parts and configure it as if it were one condenser from the outside. This is possible, and even in such a case, the condensing chamber is divided into four parts, each having a pressure difference, and therefore falls within the scope of the present invention. That is, the present invention includes all cases where the condensing pressure is functionally divided into a plurality of parts.

Note that not only the case where the number of stages of the compressor is four, but also the case where the compressor has multiple stages, the gist of the present invention is applicable to all cases and belongs to the scope of the present invention.

According to the present invention, since the flow of motor cooling gas is based on the pressure difference between a plurality of condensers, it is possible to provide a heat pump with a simple motor structure without the need to incorporate a fan into the motor, which is extremely practical in practice. It can have great effects.

[Brief explanation of the drawing]

The drawing is a flow diagram illustrating an embodiment of the invention. 1... Evaporator, 2... Piping, 3... Suction pipe, 46-... Suction header, 5.5', 5'', 5'''... Suction pipe, 6... Compressor, 7.7' , 7'', 7'''... Impeller, 8.8', 8'', 8'''... Condenser, 9... Pump, 10... Load fluid inlet, 11... Load fluid outlet, 1
2.12', +2", +2"'...Piping, +3
．． 13゜+3", +3"...expansion device, 14.
・Piping, 15...Motor, 16...Stator, 17...
Rotor, 18...Piping. Patent Applicant Ebara Corporation Representative Patent Attorney Masaru Takagi Sen Yukuma 1) Twisting Takao Maruyama 7-

Claims (1)

[Claims] 1. An evaporator, a multi-stage compressor, a plurality of condensers, and a plurality of expansion devices are provided, and the plurality of condensers are arranged to be sequentially cooled in series by the fluid to be heated, and the compressor is driven by an electric motor, and the motor is cooled by refrigerant gas guided to the electric motor from a high-pressure gas flow path downstream of the fluid to be heated, and the refrigerant gas that cooled the electric motor is cooled by the high-pressure gas flow upstream of the fluid to be heated. A heat pump characterized by being introduced into a flow path.