JPS6340759Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention is a refrigeration cycle for a heat pump used as an air conditioner or a water heater. The present invention relates to an engine-driven heat pump configured to provide circulating flow across an evaporator and the compressor.

In this type of heat pump, for example, when the condensing action in the condenser decreases, that is, as the condensing load increases, the pressure in the high-pressure refrigerant flow path from the compressor to the expansion valve gradually increases. If refrigeration operation continues under load conditions, there are problems such as damage to the compressor and seizure of the engine.

Conventionally, as a means of protecting the engine and compressor in the event of such overload, the transmission system from the engine to the compressor is equipped with a system that detects a load on the transmission system from the engine to the compressor, based on the detection results of an engine load detection device, when the detected load increases beyond a set value. There is a means to cut off the drive of the compressor, such as by intervening a clutch that is automatically disconnected or activated when the engine load increases beyond a set value, or by providing a device that automatically stops the engine drive when the engine load increases beyond a set value. However, this method had the disadvantage that the refrigeration operation was frequently interrupted and the desired air conditioning and hot water supply functions could not be performed sufficiently.

Therefore, the inventors of the present invention have designed the following configurations (a) and (b) to be able to protect the engine and compressor during overload while continuing refrigeration operation. Application (1986-214757) was filed first.

(a) A bypass path is provided between the high-pressure refrigerant flow path from the compressor to the expansion valve and the low-pressure refrigerant flow path from the evaporator to the compressor.

(b) A valve that is automatically controlled to open and close based on the increase or decrease in load detected by the engine load detection device is interposed in the bypass path.

With the configurations (a) and (b), even when the pressure in the high-pressure side refrigerant flow path increases due to a decrease in the condensing effect in the condenser, the resulting increase in engine load can be avoided. Based on this, the valve of the bypass passage is automatically controlled to open, and a part of the refrigerant in the high-pressure side refrigerant passage is short-circuited to the low-pressure side refrigerant passage. The engine and compressor can be protected by the pressure drop in the area.

However, in the earlier application mentioned above, the engine exhaust temperature was detected or the engine coolant temperature was detected as a means of detecting the engine load; in the former case, the engine exhaust temperature was detected. reacts sensitively to engine load fluctuations, it is easy to detect temporary engine load fluctuations and unnecessarily control the opening/closing of the valve; Since temperature changes are slow, the valves continue to be controlled to open and close even after the engine load returns to within the set range until the cooling water temperature returns to within the set range.

The purpose of the present invention is to improve the above-mentioned drawbacks in valve opening/closing control, and its characteristic configuration is a device that detects when the engine exhaust temperature rises above a set value. When both the device and the device that detects that the engine coolant temperature has risen above a set value are activated, the safety valve that opens and closes the bypass path is controlled to open, and in other detection conditions, the safety valve is controlled to close. Because of this, the following effects can be obtained.

In other words, by using the engine exhaust temperature, which responds sensitively to engine load fluctuations, and the engine cooling water temperature, which responds slowly to engine load fluctuations, as AND conditions for valve control, the valve control can be controlled based on temporary engine load fluctuations. By minimizing unnecessary opening/closing control of the valves and unnecessary opening/closing control of the valves even after the engine load has returned to within the set range, the engine and compression We were able to protect the aircraft.

Hereinafter, embodiments of the present invention will be described based on the drawings.

To configure the refrigeration cycle of an engine-driven heat pump, pressurized refrigerant from a compressor 3 connected to an engine 1 via a clutch 2 is transferred to a condenser 4, an expansion valve 5, an evaporator 6, an accumulator 7, and the compressor. The structure is configured to circulate the flow over three parts.

In this heat pump, the latent heat of condensation of the refrigerant during heat exchange in the condenser 4 is used as a heating source for heating or hot water supply, or the latent heat of vaporization of the refrigerant during heat exchange in the evaporator 6 is used for cooling. Or it can be used as a cooling source for freezing.

Therefore, the exhaust manifold 1A of the engine 1
A temperature switch (an example of a detection device) 9 that is turned on when the engine exhaust temperature rises above a set value is provided in the exhaust pipe 8 that is connected to the engine. A temperature switch (an example of a detection device) 10 that is turned on when the cooling water temperature rises above a set value is provided, and a high pressure side refrigerant flow path section _a1 between the condenser 4 and the expansion valve 5 is provided. A bypass passage 13 with a throttling device 12 is provided between the evaporator 6 and the low-pressure refrigerant flow passage _a2 between the accumulator 7, and the bypass passage 13 is provided with the temperature switches 9 and 1.
An electromagnetic valve is interposed as a safety valve 14 that is automatically and reversibly controlled to open when both of the two valves are detected. The temperature switch 9 and the temperature switch 1
0 and the solenoid valve 14 are connected in series as shown in FIG. 2, and constitute a control mechanism that controls the solenoid valve 14 to open only when both temperature switches 9 and 10 are detected.

When the engine load increases due to an increase in pressure in the high-pressure refrigerant flow path due to a decrease in the condensing action in the condenser 4, this is detected by the temperature switches 9 and 10, and the electromagnetic The valve 14 is automatically opened and a part of the refrigerant that has passed through the condenser 4 is passed through the bypass path 13 to the low pressure side refrigerant flow path _a2.
By causing the refrigerant to short-circuit and flow, the pressure in the high-pressure side refrigerant flow path portion is reduced, and the engine 1 and compressor 3 can be protected by reducing the load associated with this.

A throttle device 12 provided in the bypass path 13
consists of a capillary tube.

In the figure, 15 is a heat exchanger that heats and raises the temperature of fluid by heat exchange with engine cooling water, and the fluid heated by this can be used for hot water supply and space heating. 16 is a pump for forced circulation of engine cooling water.

As another embodiment, the bypass passage 13 is provided from a high-pressure refrigerant passage between the compressor 3 and the condenser 4 to a low-pressure refrigerant passage between the evaporator 6 and the compressor 3. It may be provided and configured.

Note that although reference numerals are written in the claims section of the utility model registration for convenience of comparison with the drawings, the present invention is not limited to the structure of the attached drawings by such entry.

[Brief explanation of the drawing]

Fig. 1 is a piping system diagram, and Fig. 2 is an electrical circuit diagram of the main parts. DESCRIPTION OF SYMBOLS 1... Engine, 3... Compressor, 4... Condenser, 5... Expansion valve, 6... Evaporator, 9... Engine exhaust temperature detection device, 10... Engine coolant temperature detection device, 13... ...Bypass path, 14...Safety valve.

Claims (1)

[Scope of utility model registration request] In an engine-driven heat pump configured to circulate and flow pressurized refrigerant from a compressor 3 driven by an engine 1 through a condenser 4, an expansion valve 5, an evaporator 6, and the compressor 3, the engine A device 9 for detecting that the exhaust gas temperature has risen above a set value and a device 10 for detecting that the engine cooling water temperature has risen above the set value are provided, and a A bypass passage 13 that is opened and closed by a safety valve 14 is provided across the high-pressure refrigerant flow path and the low-pressure refrigerant flow path from the evaporator 6 to the compressor 3. 10. An engine-driven heat pump characterized in that the engine-driven heat pump is provided with a control mechanism that controls the safety valve 14 to open when both of the safety valves 10 and 10 detect a temperature equal to or higher than a set value, and controls the safety valve 14 to close in other detection states.