JPH06129729A - Stirling engine driven heat pump device - Google Patents

Abstract

PURPOSE:To reduce the number of operating gas tank by a method wherein the opening degree of an auxiliary expansion valve is controlled based on the suction side pressure of a compressor for a refrigerant circuit while cooling water for a Stirling engine is introduced into a refrigerant-cooling water heat exchanger. CONSTITUTION:A branched refrigerant circuit 23 is provided in parallel to indoor heat exchangers 16, 17 in a refrigerant circuit 11 while a refrigerant flow passage for an auxiliary expansion valve 24 and a refrigerant-cooling water heat exchanger 25 is arranged in the branched refrigerant circuit 23. On the other hand, the cooling water flow passage of the refrigerant-cooling water heat exchanger 25 is arranged in a cooling water circuit 26 wherein a radiator 19 is arranged. Further, a bypass circuit 27, connecting the upstream side of the auxiliary expansion valve 24 and the downstream side of the refrigerant-cooling water heat exchanger 25, is arranged in the branched refrigerant circuit 23 while an expansion valve 28 is arranged in the bypass circuit 27. The opening degree of the auxiliary expansion valve 24 is controlled by detecting a refrigerant pressure at a point P1 through a pressure detecting means and controlling the same based on the output of the pressure detecting means. Further, the opening degree of the expansion valve 28 is controlled based on the refrigerant pressure at a point P2 and the superheating degree of the refrigerant at the same point P2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a Stirling engine drive type heat pump device, and more particularly to a heat pump device which operates during cooling operation.

[0002]

Various types of conventional Stirling engine driven heat pump devices have been proposed, but generally, a compressor, an outdoor heat exchanger, an expansion valve and a plurality of indoor heat exchanges are provided on a refrigerant circuit. A compressor is installed and the compressor is driven by a Stirling engine.

Since a plurality of indoor heat exchangers can be turned on / off independently of each other, the amount of the refrigerant flowing through the refrigerant circuit depends on the load condition of the refrigerant circuit (the number of operating indoor heat exchangers, indoor set temperature, and indoor temperature). (Difference from temperature, etc.). Therefore, in a heat pump device driven by a gas engine or the like, the number of revolutions of the gas engine is made variable to cope with a change in the amount of refrigerant.

[0004]

However, the Stirling engine, which is an external combustion engine, can easily change the number of revolutions by changing the supply air amount or the fuel supply amount like a gasoline engine or a gas engine. Instead, for example, the working gas pressure in the working space is changed to change the rotation speed.
However, when the number of indoor heat exchangers connected is large and it is necessary to have a large control range of the number of revolutions, prepare multiple gas tanks with different filling pressures and select the gas tank connected to the working gas space. Have to control.
For this reason, there is a problem that the equipment becomes large and the safety measures become complicated.

Therefore, in the present invention, the reduction of the working gas tank of the Stirling engine drive type heat pump device is
This is a technical issue.

[0006]

[Constitution of the invention]

[0007]

The technical means of the present invention taken to solve the above-mentioned technical problems of the present invention include a refrigerant circuit, a compressor arranged on the refrigerant circuit, and outdoor heat exchange. In a Stirling engine drive type heat pump device having a heat exchanger, an expansion valve and a plurality of indoor heat exchangers and a Stirling engine for driving a compressor, an auxiliary expansion valve and a refrigerant-cooling water heat exchanger are provided in parallel with the indoor heat exchanger. Is provided, the opening degree of the auxiliary expansion valve is controlled based on the compressor suction side pressure of the refrigerant circuit, and the cooling water of the Stirling engine is introduced into the refrigerant-cooling water heat exchanger.

[0008]

According to the above-described technical means of the present invention, when some of the plurality of indoor heat exchangers stop operating, the pressure on the compressor suction side of the refrigerant circuit decreases, and the branch refrigerant circuit is cooled. The auxiliary expansion valve is opened, and the cooling water of the Stirling engine and the refrigerant exchange heat with the refrigerant-cooling water heat exchanger.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments embodying the technical means of the present invention will be described below with reference to the accompanying drawings.

In the Stirling engine driven heat pump device 10 shown in FIG. 1, a compressor 12, an outdoor heat exchanger 13, a plurality of expansion valves 14 and 15 and a plurality of indoor heat exchangers 16 and 17 are arranged on a refrigerant circuit 11. Set up. Compressor 12
Is driven by a Stirling engine 18, and its high-temperature cooling water is cooled by a radiator 19 which can be thermally coupled to the outdoor heat exchanger 13. The outdoor heat exchanger 13 and the indoor heat exchangers 16 and 17 have fans 20 and 2 respectively.
1, 22 are arranged to enhance the heat exchange efficiency in each heat exchanger. In this embodiment, the number of indoor heat exchangers is two, but the number is not limited to this number, and it goes without saying that any number may be used.

In the refrigerant circuit 11, the indoor heat exchanger 1
A branch refrigerant circuit 23 is arranged in parallel with Nos. 6 and 17, and an auxiliary expansion valve 24 and a refrigerant flow path of the refrigerant-cooling water heat exchanger 25 are arranged on the branch refrigerant circuit 23. Further, the cooling water flow path of the refrigerant-cooling water heat exchanger 25 is arranged on the cooling water circuit 26 in which the radiator 19 is arranged.

Further, in the branch refrigerant circuit 23, a bypass circuit 27 connecting the upstream side of the auxiliary expansion valve 24 and the downstream side of the refrigerant-cooling water heat exchanger 25 is arranged, and the expansion valve is provided on the bypass circuit 27. 28 are provided.

The opening of the auxiliary expansion valve 24 is controlled on the basis of the suction side pressure of the compressor 12 of the refrigerant circuit 11. Specifically, the refrigerant pressure at the point P1 is detected by pressure sensing means (pressure sensor or differential pressure). It is sensed by a drive type actuator, etc., and controlled based on the output. In addition, the expansion valve 28
The opening degree of is controlled based on the refrigerant pressure and the degree of refrigerant superheat at point P2.

Reference numeral 29 indicates an outdoor unit, and reference numerals 30 and 31 indicate a plurality of indoor units.

The operation of the Stirling engine drive type heat pump device 10 having the above construction will be described below.

It is assumed that the user turns on a main switch (not shown) of the Stirling engine drive type heat pump device 10, and first, all of the plurality of indoor units 30, 31 are in an operating state. At this time, since the Stirling engine 18 is started to drive the compressor 12,
The refrigerant circulates in the refrigerant circuit 11. Since the present embodiment is effective only during the cooling operation of the Stirling engine driven heat pump device 10, each operation during the cooling operation will be described below.

The gaseous high-temperature and high-pressure refrigerant discharged from the compressor 12 is condensed by a heat exchanger 13 which removes lubricating oil and then radiates heat to the outside air by an outdoor heat exchanger 13 to condense it. It becomes a high temperature and high pressure refrigerant. Next, after passing through a receiver (not shown), the expansion valves 14 and 15 expand it to become a liquid low-temperature low-pressure refrigerant, which absorbs heat from the indoor air in the indoor heat exchangers 16 and 17 and evaporates to a gaseous low temperature.・ It becomes a low-pressure refrigerant. in this way,
Since the refrigerant absorbs heat from the indoor air, the room is cooled. Then, the gaseous low temperature / low pressure refrigerant is sucked into the compressor 12 after passing through an accumulator (not shown).
The opening degrees of the expansion valves 14 and 15 are controlled based on the refrigerant pressure and the refrigerant superheat degree on the suction side of the compressor 12.

The rotational speed of the Stirling engine 18 is controlled according to the load state of the compressor 12 (the number of operating indoor units 30, 31 and the difference between the set temperature and the indoor temperature). Since all of 30 and 31 are in the operating state, the refrigerant discharge amount of the compressor 12 is equal to the indoor unit 3
The values 0 and 31 are variable depending on the difference between the set temperature Tset in the room in which it is installed and the actual room temperature Treal. That is, the larger the difference between the set temperature Tset and the room temperature Treal, the larger the refrigerant discharge amount of the compressor 12, and the smaller the difference, the smaller the refrigerant discharge amount of the compressor 12 is controlled.
The rotation speed of the Stirling engine 18 changes according to the refrigerant discharge amount of the compressor 12. However, since the variation width of the rotation speed is relatively small, it can be dealt with by making the working gas pressure of the Stirling engine 18 variable within a small range.

Now, if the operation of a certain indoor unit is stopped, the pressure at the point P1 will drop almost at the same time as the stop of the operation. Point P if the number of stopped indoor units is small
The degree of pressure drop of 1 is small, and the excess refrigerant in the refrigerant circuit 11 due to the decrease in the number of operating indoor units can be dealt with by lowering the rotation speed of the Stirling engine 18. However, when the number of stopped indoor units increases, the Stirling engine 1
Since the control width of the rotation speed of 8 is limited, point P1
The pressure drops below a certain set value and the auxiliary expansion valve 24 is opened.

As a result, the refrigerant flowing through the outdoor heat exchanger 13 flows into the operating indoor unit and the branch refrigerant circuit 23.
It also flows to. The refrigerant flowing into the branch refrigerant circuit 23 is expanded by the auxiliary expansion valve 24 to become a liquid low temperature / low pressure refrigerant, and the refrigerant-cooling water heat exchanger 25 is used for the Stirling engine 18
It absorbs heat from the high temperature cooling water and evaporates to become a gaseous low temperature low pressure refrigerant. In order to adjust the degree of superheat of the refrigerant at point P2, the expansion valve 28 is opened appropriately based on this degree of superheat.

Therefore, even when some of the plurality of indoor units stop operating, the refrigerant-cooling water heat exchanger 25 takes the place of the indoor heat exchanger that is not in operation, so that the compressor 12 of the compressor 12 is operated. The control range of the rotation speed of the Stirling engine 18, which is the drive source, can be small. As a result, it is possible to reduce the number of working gas tanks and improve the safety because a large number of working gas tanks are not required unlike the conventional case.

[0022]

As described above, in the Stirling engine drive type heat pump device of the present invention, when some of the plurality of indoor heat exchangers stop operating, the compressor suction side pressure of the refrigerant circuit decreases. The auxiliary expansion valve of the branch refrigerant circuit is opened. As a result, since the excess refrigerant and the cooling water of the Stirling engine are heat-exchanged in the refrigerant-cooling water heat exchanger, it is not necessary to reduce the rotation speed of the Stirling engine to reduce the refrigerant circulation amount, and The amount of change in the number of rotations can be reduced.

Further, since the cooling water of the Stirling engine is dissipated not only by the radiator but also by the refrigerant-cooling water heat exchanger, the cooling water temperature of the Stirling engine is lowered and the engine thermal efficiency is improved as a characteristic of the Stirling cycle.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a Stirling engine drive type heat pump device 10 according to an embodiment of the present invention.

[Explanation of symbols]

 10 Stirling engine drive type heat pump device, 11 Refrigerant circuit, 12 Compressor, 13 Outdoor heat exchanger, 14,15 Expansion valve, 16,17 Indoor heat exchanger, 18 Stirling engine, 23 Branch refrigerant circuit, 24 Auxiliary expansion valve, 25 Refrigerant-cooling water heat exchanger.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Masahiro Ichikawa, Hiroshi Ichikawa 2-chome, Asahi-cho, Kariya-shi, Aichi Aisin Seiki Co., Ltd. (72) Inventor Makoto Nakamura 3-2-1 Nishikubo, Musashino-shi, Tokyo −209 (72) Inventor Yoshiharu Ito 19-18 Sakurada-cho, Atsuta-ku, Nagoya-shi, Aichi Toho Gas Co., Ltd.

Claims (1)

[Claims] 1. A Stirling engine having a refrigerant circuit, a compressor, an outdoor heat exchanger, an expansion valve and a plurality of indoor heat exchangers arranged on the refrigerant circuit, and a Stirling engine for driving the compressor. In the drive heat pump device, a branch refrigerant circuit having an auxiliary expansion valve and a refrigerant-cooling water heat exchanger is provided in parallel with the indoor heat exchanger, and an opening of the auxiliary expansion valve is set to the compressor suction of the refrigerant circuit. A Stirling engine drive type heat pump device, characterized in that the cooling water of the Stirling engine is introduced into the refrigerant-cooling water heat exchanger while controlling based on the side pressure.