Rotary compressor and heat pump system

Abstract

A problem to be solved by the present invention is that the temperature of a refrigerant discharged from a compression section can be detected more exactly without being influenced by variable factors existing around the compression section. In a rotary compressor 1 having a motor 6 and a compression section 3 provided in a closed container 2, and also having a discharge pipe 26 provided in an upper part of the closed container 2 to discharge a refrigerant compressed by the compression section 3 to the outside of the closed container 2, a refrigerant discharge part 462 for discharging the refrigerant compressed by the compression section 3 toward the inner peripheral surface of the closed container 2 is provided, and a discharge temperature sensor 20 for detecting the discharge temperature of compressed refrigerant is arranged in a portion opposed to the refrigerant discharge part 462 on the outer peripheral surface side of the closed container 2.

Description

TECHNICAL FIELD[0001]The present invention relates to a rotary compressor used for air conditioners and water heaters. More particularly, it relates to a technique used to control the capacity of a heat pump system and to ensure the reliability of a compressor by exactly detecting the discharge temperature of a refrigerant compressed by a compression section.BACKGROUND ART[0002]The compressor used for the refrigeration cycle of a heat pump system has a problem in that if the degree of superheat of the intake refrigerant thereof is too high, the density of intake refrigerant decreases, so that the capacity and efficiency of compressor decreases, and a problem in that the temperature of the whole of the compressor rises, so that the reliability of compressor, especially the durability of motor winding and insulating paper, decreases.[0003]On the other hand, if the intake refrigerant is not in a superheated state but in a wet state, that is, in a state in which the ratio of liquid is h...

AI Technical Summary

Benefits of technology

[0025]A heat pump system provided with a gas injection cycle, which includes a basic refrigeration cycle in which a compressor, a condenser, a basic cycle expansion mechanism, and an evaporator are connected in succession by a line; a branch pipe which branches some of a high-pressure refrigerant behind the outlet of the condenser from the basic refrigeration cycle as an injection refrigerant; an injection expansion mechanism which decompresses the injection refrigerant to an intermediate pressure between the pressure of the condenser and the pressure of the evaporator; an internal heat exchanger which heat-exchanges the decompressed injection refrigerant with the branched high-pressure refrigerant of basic refrigeration cycle; an injection line which sucks the injection refrigerant, having been subjected to the heat exchange, during the compression process of the compressor; and a control unit which detects the temperatures of a plurality of locations of the refrigeration cycle and controls the number of revolutions of the compressor, the throttle amount of the basic cycle expansion mechanism, and the throttle amount of the injection expansion mechanism, wherein the rotary compressor described in claim 8 is used as the compressor, the discharge pipe of the compressor is connected to the condenser, the low-pressure suction pipe of the compressor is connected to the evaporator, and the intermediate-pressure suction pipe of the compressor is connected to the injection line; and based on the temperature detected by a discharge temperature sensor provided on the outer peripheral surface of a closed container of the compressor, the throttle amount of the injection expansion mechanism and the number of revolutions of the compressor are controlled, and the degree of superheat or the dryness of a refrigerant sucked into the intermediate-pressure suction pipe of the compressor is kept proper.

[0027]According to the present invention, in the rotary compressor in which the motor and the compression section are contained in the closed container, the temperature of refrigerant discharged from the compression section can be detected more exactly without being influenced by variable factors, such as the motor, existing around the compression section.

[0028]Thereby, the state of refrigerant sucked into the compressor, that is, the degree of superheat or the dryness thereof can be estimated more exactly, and therefore the capacity of heat pump system can be controlled and the reliability of compressor can be ensured at a low cost.

[0029]Also, in a speed variable compressor, in the case where the required capacity as a heat pump system is low and the number of revolutions is small, that is, in the case where the refrigerant circulating amount is small, the change in temperature caused by an influence of the surroundings from immediately after the discharge from the compression section to the discharge pipe in the upper part of the compressor is large, so that the effect of the present invention increases.

[0030]Further, according to the present invention, in the gas injection cycle, the degree of superheat or the dryness of injection refrigerant sucked into the compressor can be kept proper.

Problems solved by technology

The compressor used for the refrigeration cycle of a heat pump system has a problem in that if the degree of superheat of the intake refrigerant thereof is too high, the density of intake refrigerant decreases, so that the capacity and efficiency of compressor decreases, and a problem in that the temperature of the whole of the compressor rises, so that the reliability of compressor, especially the durability of motor winding and insulating paper, decreases.

On the other hand, if the intake refrigerant is not in a superheated state but in a wet state, that is, in a state in which the ratio of liquid is high, the lubricating oil in the compression section is diluted by a liquid refrigerant, resulting in poor lubrication.

If the ratio of liquid increases further, the intake refrigerator becomes in a liquid compression state, which presents a problem in that an abnormal rise in pressure leads to damage of compression section.

However, the mode in which the discharge temperature sensor is provided in the discharge pipe above the compressor as in Patent Document 1 has problems described below.

Therefore, this method is insufficient for detecting exact temperature immediately after the discharge from the compression section, which is necessary for estimating the degree of superheat of intake refrigerant, so that this method must be improved.

Also, in the mode in which the discharge temperature sensor is provided within the compressor as in Patent Document 2, since the signal of the discharge temperature sensor is taken out to the outside, a pressure-tight junction terminal must be provided in the closed container of compressor, which leads to an increase in cost, so that this method must be improved.

Images