JPH0384372A - Engine driven heat pump - Google Patents

Abstract

PURPOSE:To improve the efficiency of heat recovery by allowing a cooling system of engine to comprise a cooling circuit which shares engine oil for an engine circulation system as refrigerant and connecting said cooling system with a heat exchanger which is installed to a refrigerant circulation system in parallel so that heat may be exchanged. CONSTITUTION:When an attempt made to drive an engine-driven heat pump for heating, a solenoid valve 17 of a supply pipe 14h for an engine waste heat recovery system is closed while a solenoid valve 18 is opened so that the engine oil which has recovered the waste heat of the engine may circulate through a circulation passage 19b. On the other hand, refrigerant flows in the direction marked with the sign A through an engine refrigerant circulation circuit 8 while a refrigerant solution robs the open air of its heat with a heat exchanger 19. Furthermore, it robs the engine oil flowing through the circulation passage 19b of its heat with a double pipe heat exchanger 9 and gets vaporized. When heating operation is carried out, the solenoid valve 17 is opened while the sole noid valve 18 is closed if an outdoor heat exchanger gets frosted. Under this condition, if an attempt is made to circulate the engine oil through the circula tion passage 19a, it will be possible to melt the frost.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an engine-driven pump in which a compressor is driven by an engine.

[Prior art]

Engine-driven heat pumps are generally designed to use waste heat from the engine for heating, from the perspective of effective energy use.

Engine cooling water is generally used to recover waste heat from the engine, and the cooling water that has recovered the waste heat is sent to a heat exchanger attached to the heat pump refrigerant circulation circuit, where it exchanges heat with the heat pump refrigerant. There is.

However, since the boiling point of engine cooling water is around 100°C, there is a limit to the amount of heat that can be recovered. Therefore, in order to achieve higher heat recovery efficiency, it is necessary to take measures such as increasing the amount of circulating cooling water. However, in order to increase the amount of circulation in this way, it is necessary to increase the size of the circulation pump, which inevitably leads to disadvantages in terms of cost and layout.

[Problem to be solved by the invention]

An object of the present invention is to provide an engine-driven heat pump that can improve the recovery efficiency of engine waste heat without increasing the size of the device.

[Means to solve the problem]

The present invention achieves the above object in an engine-driven heat pump in which a compressor is driven by an engine. It is characterized by being connected to a heat exchanger attached to the refrigerant circulation circuit for heat exchange.

In this way, since engine oil having a higher boiling point and larger heat capacity than conventional engine cooling water is used for waste heat recovery, heat recovery efficiency can be increased. Furthermore, if the same amount of waste heat is to be recovered as in the case of cooling water, a circulation pump with a smaller capacity can be used, making it possible to downsize the device.

〔Example〕

FIG. 1 schematically shows the main parts of an engine-driven heat pump according to an embodiment of the present invention.

1 is a gas engine, 2 is a piston, and 3 is a crankshaft. The gas engine 1 is driven by a fuel gas such as city gas or propane gas supplied from a supply pipe 4, and exhausts the exhaust gas after combustion through an exhaust pipe 5.

A compressor 6 is connected to one end of the crankshaft 3, and the compressor 6 compresses the refrigerant into a high-temperature, high-pressure gas, sends it out to a discharge pipe 7, and then forces the refrigerant into a heat pump refrigerant circulation circuit 8 consisting of a known tank bottom. That's what I do.

The refrigerant circulation path 8 is connected not only to an indoor heat exchanger and an expansion valve (not shown), but also to a double front heat exchanger 9 and an outdoor heat exchanger 10 shown in the figure. In this heat pump refrigerant circulation circuit 8, a refrigerant circulates in the direction shown by arrow A during heating, and in the opposite direction as shown by arrow B during cooling.

At the other end of the crankshaft 3, an engine oil supply pump 11
and the circulation pump 12 are driven. Further, since the engine 1 uses a dry sump type for lubrication, an oil tank 13 is provided on the outside. The supply pump 11 is designed to suck engine oil from an oil tank 13 and discharge it to a supply pipe 14, and the supply pipe 14 is branched into three routes: a supply pipe 14e and a supply pipe 14h. One supply pipe 14e sends engine oil at high pressure to the lubrication system in the engine 1, and the other supply pipe 14h sends engine oil at low pressure but at a large amount to the engine waste heat recovery system. The reason for supplying oil to the engine lubrication system at high pressure is to ensure smooth supply of engine oil to the entire engine, since oil passages in the lubrication system are generally narrow.

The supply pipe 14h of the engine waste heat recovery system is connected to a heat exchanger (jacket) 15 for cooling the engine and a heat exchanger 16 provided in the exhaust pipe 5, and these heat exchangers 15.1
6 to recover engine waste heat. The supply pipe 14h exiting the heat exchanger 16 is divided into two circulation paths 19a and 19b via electromagnetic valves 17 and 18, and is configured to flow selectively into either of the circulation paths. One circulation path 19a is configured to flow back to the oil tank 13 via a heat exchanger 20 installed opposite to the outdoor heat exchanger 10 of the heat pump refrigerant circulation circuit 8, and the other circulation path 19b is configured to flow back the heat pump refrigerant to the oil tank 13. The oil is also refluxed to the oil tank 13 via a double preheat exchanger 9 provided in the circulation circuit 8. 2
2 is a capillary tube, which serves as a bumper when excessive pressure is applied.

The other circulation pump 12 is configured to return engine oil sent into the engine 1 for lubrication at high pressure from the supply pipe 14e to the oil tank 13 again.

When the above-mentioned engine-driven heat pump is operated for heating, the solenoid valve 17 of the supply pipe 14h of the engine waste heat recovery system is closed, and the solenoid valve 18 is opened, so that the engine oil that has recovered the engine waste heat is circulated. It circulates through path 19b. On the other hand, in the heat pump refrigerant circulation circuit 8, the refrigerant flows in the direction of the arrow A, and the refrigerant liquid takes heat from the outside air in the heat exchanger 10, and further heats from the engine oil flowing in the circulation path 19b in the double front heat exchanger 9. It takes away and evaporates. During this heating operation, depending on outside air conditions, frost may form on the outdoor heat exchanger 10, reducing heat exchange efficiency. If frost forms in this way, open the solenoid valve 17 and close the solenoid valve 18.
If the valve is closed and the engine oil is circulated toward the circulation path 1.9a, the frost that has formed can be melted.

In the above heat pump, the engine oil used for engine waste heat recovery has a very high boiling point (generally about 140°C) and a large heat capacity compared to conventional engine cooling water, so it can improve heat recovery efficiency. can do.

In addition, because of this high heat recovery efficiency, circulation pumps (
The supply pump) can also be made smaller, which is advantageous in terms of cost and layout.

FIG. 2 shows another embodiment of the invention.

The embodiment shown in FIG. 1 uses a dry sump type for engine lubrication, but the embodiment shown in FIG. 2 differs in that it uses a wet sump type. For this reason, the engine 1 has an oil reservoir 13° on the bottom surface of the crankcase. In addition, as engine oil supply pumps, there is a supply pump lla for the engine lubrication system and a supply pump l for the engine waste heat recovery system.
lb and are provided independently from each other. The supply pump lla sends oil at a high pressure, but the supply pump llb has a lower pressure than this and is capable of sending a large amount of engine oil. Further, an air separator 21 is connected to a portion where the circulation paths 19a and 19b join, so that the air in the engine oil is separated there and then returned to the oil sump 13'.

In this embodiment, similarly to the first embodiment, during heating operation, engine oil from which engine waste heat has been recovered passes through the double-pipe heat exchanger 9 via the circulation path 19b, and at this time, the heat pump refrigerant circulation circuit 8 The refrigerant is evaporated by exchanging heat with the refrigerant liquid.

Furthermore, since engine oil is used for waste heat recovery, heat recovery efficiency is high and the device can be downsized.

〔Effect of the invention〕

As described above, the heat pump of the present invention is configured such that the engine cooling system is configured with a cooling circuit that shares the engine oil of the engine lubrication system as a refrigerant, and the cooling circuit is capable of heat exchange with the refrigerant circulation circuit of the heat pump. It is designed to be connected to an attached heat exchanger, and uses engine oil with a higher boiling point and larger heat capacity than conventional engine cooling water as the refrigerant for engine waste heat recovery, increasing heat recovery efficiency. can do. Furthermore, the device including the supply pump that circulates the engine oil can be downsized, which is advantageous in terms of cost and layout.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of the main parts of an engine-driven heat pump according to an embodiment of the present invention, and FIG. 2 is a schematic diagram of the main parts of an engine-driven heat pump according to another embodiment. 1... Gas engine, 3... Crankshaft, 5...
Exhaust pipe, 6... Compressor, 8... Refrigerant circulation circuit (for heat pump), 9... Double pipe heat exchanger, 10°15.16.20... Heat exchanger, 11. lla, 1- 1b... Supply pump, 13... Oil tank, 13°.
...Oil sump, 14e, 14h-Supply pipe, 19a, 19
b - circulation path;

Claims (1)

[Claims] In an engine-driven heat pump in which a compressor is driven by an engine, the engine cooling system is configured with a cooling circuit that shares engine oil in the engine lubrication system as a refrigerant, and the cooling circuit is attached to the refrigerant circulation circuit of the heat pump so as to be able to exchange heat. engine-driven heat pump connected to a heated heat exchanger.