Refrigerant circulating system

• US 5,737,931 A
• Filed: 06/21/1996
• Issued: 04/14/1998
• Est. Priority Date: 06/23/1995
• Status: Expired due to Term

• Current Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Inventors: Ueno, Yoshio, Sumida, Yoshihiro, Morimoto, Osamu, Kasai, Tomohiko
• Primary Examiner(s): Wayner, William E.
• Application Number:
  US08/668,155
• Time in Patent Office: 662 Days
• Field of Search: 62/126, 62/502, 62/228.4, 62/204
• US Class Current: 62/126
• CPC Class Codes: F25B 13/00 Compression machines, plants or systems, with reversible cycle defrosting cycles F25B47/02
• CPC Class Codes: F25B 2313/023 using multiple indoor units
• CPC Class Codes: F25B 2313/0294 related to the outdoor fan, e.g. controlling speed
• CPC Class Codes: F25B 2313/0314 Temperature sensors near the indoor heat exchanger
• CPC Class Codes: F25B 2400/08 Refrigeration machines, plants and systems having means for detecting the concentration of a refrigerant
• CPC Class Codes: F25B 2600/02 Compressor control
• CPC Class Codes: F25B 2600/2513 Expansion valves
• CPC Class Codes: F25B 2700/1931 Discharge pressures
• CPC Class Codes: F25B 41/385 Dispositions with two or more expansion means arranged in parallel on a refrigerant line leading to the same evaporator
• CPC Class Codes: F25B 9/006 the refrigerant containing more than one component F25B9/004 takes precedence

Abstract

A refrigerant circulating system using non-azeothropic mixture as refrigerant, which comprises: a main refrigerant circuit connected by a compressor, a fore-way valve, an outdoor heat-exchanger, a first throttling device, a plurality of indoor heat-exchangers, and a low-pressure receiver; a bypass circuit diverging from the discharge portion of the compressor, and extending through a composition detecting heat-exchanger and a second throttling device to a low-pressure portion; an outdoor fun attendant of the outdoor heat-exchanger; first temperature detector to detect a refrigerant temperature at the upstream of the second throttling device; second temperature detector to detect a refrigerant temperature at the downstream of the second throttling device; first pressure detector to detect a pressure at the downstream of the second throttling device; third temperature detector to detect temperature in the main circuit between the first throttling device and the indoor heat-exchanger; forth temperature detector to detect temperature at the low-pressure portion; second pressure detector to detect the pressure at the high-pressure portion; a composition calculating device for calculating the composition of the mixture refrigerant; a main controller for controlling the number of rotation of the compressor and the number of rotation of an outdoor fun; a throttle controller for controlling the opening of the first throttling device.

Claims

1. A refrigerant circulating system comprising:

a main refrigerant circuit for circulating mixture refrigerant, said main refrigerant circuit including a compressor, a directional control valve, a condenser, a first throttling device and an evaporator;

a bypass circuit diverging from a point between a discharge portion of said compressor and said directional control valve, and connected through a composition detecting heat-exchanger and a second throttling device to a point between an intake portion of said compressor and said directional control valve;

first temperature detecting means located to a point between said composition detecting heat-exchanger and said second throttling device, said first temperature detecting means detecting refrigerant temperature at an upstream of said second throttling device;

second temperature detecting means located to a point between said composition detecting heat-exchanger and said second throttling device, said second temperature detecting means detecting refrigerant temperature at a downstream of said second throttling device;

first pressure detecting means located at an intake side of said compressor, and for detecting a pressure of refrigerant at its located place;

a composition calculating device for calculating a composition of mixture refrigerant on the basis of the detected refrigerant temperature and pressure;

second pressure detecting means located at the discharge side of said compressor, and for detecting the pressure of refrigerant at its located place; and

a main controller for controlling at least compressor speed or fan speed provided to said condenser or evaporator, on the basis of the calculated composition of refrigerant and detected pressure of refrigerant.

2. A refrigerant circulating system as claimed in claim 1, wherein said main refrigerant circuit further includes a an accumulator, and the bypass circuit is connected to a point between the accumulator and the directional control valve;

the refrigerant circulating system further comprising a third throttling device for coupling a high-pressure side inlet of said composition detecting heat-exchanger and a low-pressure side outlet of said composition detecting heat-exchanger.

3. A refrigerant circulating system as claimed in claim 1, wherein said main refrigerant circuit includes an outdoor heat-exchanger and an indoor heat-exchanger, said compressor, said outdoor heat-exchanger and said bypass circuit being housed within an outdoor machine.

4. A refrigerant circulating system as claimed in claim 1, further comprising:

a throttle controller for controlling the opening of said first throttling device; and

a total controller including a timer and for controlling the control timings of said composition calculating device, main controller and throttle controller.

5. A refrigerant circulating system as claimed in claim 4, wherein the control timing of said total controller is controlled on the basis of the time interval of the composition calculation of said composition calculating device.

6. A refrigerant circulating system as claimed in claim 4, wherein a first throttling device for a indoor machine which is not in operation is controlled to have a predetermined opening at the time of the heating operation.

7. A refrigerant circulating system as claimed in claim 4, wherein a first throttling device for a indoor machine which is not in operation is controlled to be closed at the time of the heating operation.

8. A refrigerant circulating system as claimed in claim 1, wherein said bypass circuit is diverged from a discharge portion of said compressor, and extended to a low-pressure portion;

said refrigerant circulating system further comprising;

is third temperature detecting means for detecting temperature in the main circuit between said first throttling device and said indoor heat-exchanger; and

forth temperature detecting means for detecting temperature at the low-pressure portion.

9. A refrigerant circulating system as claimed in claim 1, wherein said composition calculating device detects a physical quantity representative of an operational state of refrigerant circulation, and changes time interval for the composition calculation when the time change of said detected value is above a predetermined value.

10. A refrigerant circulating system as claimed in claim 1, wherein said indoor heat-exchanger comprises a plurality of heat-exchangers adapted to be operated so that a part thereof is in operation and the other is not in operation.

11. A refrigerant circulating system as claimed in claim 10, wherein a respective first throttling device for a respective indoor machine which is not in operation is controlled so that it is opened at different timings, when refrigerant resident in the indoor machines which are not in operation is returned to the main circuit.

12. A refrigerant circulating system as claimed in claim 1, wherein said second throttling device and a pipe portion between said second throttling device and said composition detecting heat-exchanger are heat-isolated.

13. A refrigerant circulating system as claimed in claim 1, wherein the circulation composition obtained through the calculation of said composition calculating device is compensated for with respect to the outside air temperature.

14. A refrigerant circulating system as claimed in claims 1, wherein the refrigerant circulating system includes a safety device for examining whether the composition calculated by said composition calculating device is within a range of a predetermined composition and stooping the unit when the examination showed that the detected composition is not within a proper range, and/or a display device for displaying the composition when its abnormality was detected.

15. A refrigerant circulating system as claimed in claim 1, wherein said main refrigerant circuit further includes an oil separator, the a bypass circuit is diverged from a point between the oil separator and the directional control valve, and a third throttling device is provided to couple the high-pressure side inlet of the composition detecting heat-exchanger to the low-pressure side outlet of the composition detecting heat-exchanger.

16. A refrigerant circulating system as claimed in claim 1, wherein said second pressure detecting means is located on a pipe connecting the inlet portion of said compressor and said directional control valve which is located at the connection of the low-pressure side of said composition detecting heat-exchanger to the pipe connecting the inlet portion of said compressor and said directional control valve.

17. A refrigerant circulating system as claimed in claim 1, wherein said second temperature detecting means is located to be separated from said second throttling device by at least a distance corresponding to pipe length through which the flow of two-phase refrigerant develops.

18. A refrigerant circulating system as claimed in claim 1, wherein pressure loss at the low-pressure side of said composition detecting heat-exchanger is set such that pressure at a low-pressure pressure sensor is substantially coincident with pressure at the inlet portion of said compressor.

19. A refrigerant circulating system as claimed in claim 1, further comprising:

a low-pressure side pressure loss calculating device for said composition detecting heat-exchanger.

20. A refrigerant circulating system as claimed in claim 1, further comprising:

a composition regulating operation controller providing an operation state in which the circulation composition is pre-known; and

a composition compensating value calculating device for calculating difference between the composition value calculated at that time and a pre-known circulation composition; and

wherein the composition calculated in said composition calculating device is compensated for on the basis of the composition compensating value which has sought at the time of the composition regulating operation.