Heat source unit and refrigeration device having low-stage and high-stage compressors with four-way switching valve

Patent metadata

Field	Value
Publication number	US-12123629-B2
Application number	US-202318371553-A
Country	US
Kind code	B2
Filing date	Sep 22, 2023
Priority date	Mar 29, 2021
Publication date	Oct 22, 2024
Grant date	Oct 22, 2024

Abstract

A heat source unit connected to a utilization-side unit and configured to perform a refrigeration cycle includes a low-stage compressor, a high-stage compressor, a four-way switching valve, a low-stage pipe, and a controller. The low-stage pipe is provided in parallel with the low-stage compressor, and the refrigerant flows therethrough while the low-stage compressor is stopped. The controller outputs an instruction signal for actuating the four-way switching valve, to the four-way switching valve while the low-stage compressor is stopped and the high-stage compressor is operating.

First claim

The invention claimed is:

1. A heat source unit connected to a utilization-side unit and configured to perform a refrigeration cycle, the heat source unit comprising:
a heat-source-side heat exchanger;
a low-stage compressor;
a high-stage compressor configured to suck and compress a refrigerant discharged from the low-stage compressor;
a four-way switching valve;
a low-stage pipe which is provided in parallel with the low-stage compressor and through which the refrigerant flows while the low-stage compressor is stopped; and
a controller, wherein
the controller is configured to activate the four-way switching valve between a first state and a second state,
wherein
in the first state, the refrigerant having evaporated in the utilization-side unit is sucked into the low-stage compressor and refrigerant discharged from the high-stage compressor is supplied to the heat-source side heat exchanger, and
in the second state, the refrigerant having evaporated in the heat source-side heat exchanger is sucked into the low-stage compressor and the refrigerant discharged from the high-stage compressor is supplied to the utilization-side unit, and wherein

the controller is further configured to:
output an instruction signal for activating the four-way switching valve to switch an operation performed by the heat source unit while the low-stage compressor is stopped and the high-stage compressor is operating, and
output the instruction signal to the four-way switching valve after stopping the low-stage compressor, if the low-stage compressor is operating at a time of switching the operation performed by the heat source unit.

2. The heat source unit of claim 1 , wherein
the four-way switching valve includes a valve element configured to be actuated by a pressure of the refrigerant.

3. The heat source unit of claim 2 , wherein
the controller outputs the instruction signal to the four-way switching valve after decreasing the rotational speed of the high-stage compressor.

4. The heat source unit of claim 3 , further comprising:
a suction pipe through which the refrigerant sucked into the low-stage compressor flows;
a discharge pipe through which the refrigerant discharged from the high-stage compressor flows;
a bypass pipe connecting the suction pipe and the discharge pipe; and
a control valve provided in the bypass pipe and having a variable opening degree, wherein
the controller outputs the instruction signal to the four-way switching valve after opening the control valve.

5. The heat source unit of claim 4 , wherein
the utilization-side unit to which the heat source unit is connected includes: a first utilization-side unit and a second utilization-side unit,
the low-stage compressor includes: a first low-stage compressor configured to suck the refrigerant from the first utilization-side unit; and a second low-stage compressor configured to suck the refrigerant from the second utilization-side unit,
the four-way switching valve switches a flow path of the refrigerant sucked into the first low-stage compressor and a flow path of the refrigerant discharged from the high-stage compressor, and
the controller outputs the instruction signal to the four-way switching valve while the first low-stage compressor is stopped and the high-stage compressor is operating.

6. The heat source unit of claim 4 , wherein
the controller opens the control valve and then outputs the instruction signal to the four-way switching valve.

7. The heat source unit of claim 2 , further comprising:
a suction pipe through which the refrigerant sucked into the low-stage compressor lows;
a discharge pipe through which the refrigerant discharged from the high-stage compressor flows;
a bypass pipe connecting the suction pipe and the discharge pipe; and
a control valve provided in the bypass pipe and having a variable opening degree, wherein
the controller outputs the instruction signal to the four-way switching valve after opening the control valve.

8. The heat source unit of claim 1 , wherein
the controller outputs the instruction signal to the four-way switching valve after decreasing the rotational speed of the high-stage compressor.

9. The heat source unit of claim 8 , further comprising:
a suction pipe through which the refrigerant sucked into the low-stage compressor lows;
a discharge pipe through which the refrigerant discharged from the high-stage compressor flows;
a bypass pipe connecting the suction pipe and the discharge pipe; and
a control valve provided in the bypass pipe and having a variable opening degree, wherein
the controller outputs the instruction signal to the four-way switching valve after opening the control valve.

10. The heat source unit of claim 1 , further comprising:
a suction pipe through which the refrigerant sucked into the low-stage compressor flows;
a discharge pipe through which the refrigerant discharged from the high-stage compressor flows;
a bypass pipe connecting the suction pipe and the discharge pipe; and
a control valve provided in the bypass pipe and having a variable opening degree, wherein
the controller outputs the instruction signal to the four-way switching valve after opening the control valve.

11. The heat source unit of claim 10 , wherein
the controller opens the control valve and then outputs the instruction signal to the four-way switching valve.

12. The heat source unit of claim 10 , wherein
the controller closes the control valve after the output of the instruction signal to the four-way switching valve.

13. The heat source unit of claim 1 , wherein
the utilization-side unit to which the heat source unit is connected includes: a first utilization-side unit and a second utilization-side unit,
the low-stage compressor includes: a first low-stage compressor configured to suck the refrigerant from the first utilization-side unit; and a second low-stage compressor configured to suck the refrigerant from the second utilization-side unit,
the four-way switching valve switches a flow path of the refrigerant sucked into the first low-stage compressor and a flow path of the refrigerant discharged from the high-stage compressor, and
the controller outputs the instruction signal to the four-way switching valve while the first low-stage compressor is stopped and the high-stage compressor is operating.

14. The heat source unit of claim 13 , further comprising:
a suction pipe through which the refrigerant sucked into the first low-stage compressor flows;
a discharge pipe through which the refrigerant discharged from the high-stage compressor flows;
a bypass pipe connecting the suction pipe and the discharge pipe; and
a control valve provided in the bypass pipe and having a variable opening degree, wherein
the controller outputs the instruction signal to the four-way switching valve after opening the control valve.

15. The heat source unit of claim 14 , wherein
the controller opens the control valve and then outputs the instruction signal to the four-way switching valve.

16. The heat source unit of claim 14 , wherein
the controller closes the control valve after the output of the instruction signal to the four-way switching valve.

17. A refrigeration apparatus comprising:
the heat source unit of claim 1 , and
a utilization-side unit connected to the heat source unit.

18. A heat source unit connected to a utilization-side unit and configured to perform a refrigeration cycle, the heat source unit comprising:
a heat-source-side heat exchanger;
a low-stage compressor;
a high

Assignees

• Daikin Ind Ltd

Inventors

• Takegami Masaaki
• Kimura Naoto
• Kaneda Masahiko

Classifications

• F25B2600/0251

  with on-off operation · CPC title

• F25B13/00

  Compression machines, plants or systems, with reversible cycle (defrosting cycles F25B47/02) · CPC title

• F25B2600/2501

  Bypass valves · CPC title

• F25B2600/025

  by controlling speed · CPC title

• F25B2400/075

  with parallel compressors · CPC title