Air conditioner using oil return operation based on outdoor air temperature

Patent metadata

Field	Value
Publication number	US-9285148-B2
Application number	US-201113499834-A
Country	US
Kind code	B2
Filing date	Jan 7, 2011
Priority date	Jan 25, 2010
Publication date	Mar 15, 2016
Grant date	Mar 15, 2016

Abstract

In an air conditioner provided with an oil-return-operation control portion that performs an oil-return operation, when oil-return conditions are satisfied, by controlling the rotational speed of a compressor, the degree of opening of an expansion valve, etc., with a predetermined refrigerant cycle and provided with high-outdoor-air-temperature oil-return operation means for performing a forced oil-return operation via the oil-return-operation control portion when an outdoor temperature increases and a state in which a detection value of an outdoor air temperature sensor is higher than a set value continues for a predetermined period of time, the oil-return operation is prohibited for a certain period of time after performing the forced oil-return operation via the high-outdoor-air-temperature oil-return operation means.

First claim

The invention claimed is:

1. An air conditioner which is provided with an oil-return-operation control portion that performs an oil-return operation, when oil-return conditions are satisfied, by controlling a compressor rotational speed and a degree of opening of an expansion valve with a predetermined refrigerant cycle, the air conditioner comprising:
an outdoor air temperature sensor; and
high-outdoor-air-temperature oil-return operation means for performing a forced oil-return operation via the oil-return-operation control portion when an outdoor temperature increases and a state in which a detection value from the outdoor air temperature sensor is higher than a set value continues for a predetermined period of time,
wherein the oil-return operation is prohibited for a certain period of time after performing the forced oil-return operation via the high-outdoor-air-temperature oil-return operation means.

2. An air conditioner according to claim 1 , wherein the forced oil-return operation due to re-detection of the outdoor air temperature at or above the set value and the oil-return operation due to detection of oil-return conditions are prohibited during the certain period of time in which the oil-return operation is prohibited.

3. An air conditioner according to claim 1 , wherein the prohibition of the oil-return operation for the certain period of time is removed when the outdoor air temperature is below the set value.

4. An air conditioner according to claim 1 , further comprising high-pressure-protection-value changing means for increasing a high-pressure-protection value, at which the compressor is halted in association with an increase in refrigerant pressure by a predetermined value, at least when performing the forced oil-returning operation via the high-outdoor-air-temperature oil-return operation means.

Assignees

• Kasagi Tsukasa
• Hiramatsu Seiji
• Tsuji Tetsuo
• Mitsubishi Heavy Ind Ltd

Inventors

• Kasagi Tsukasa
• Hiramatsu Seiji
• Tsuji Tetsuo

Classifications

• F25B43/02 Primary

  for separating lubricants from the refrigerant · CPC title

• F25B31/004

  oil recirculating arrangements · CPC title

• F25B2500/16

  Lubrication · CPC title

• F25B2700/2106

  of fresh outdoor air · CPC title

• F25B1/00

  Compression machines, plants or systems with non-reversible cycle (F25B3/00, F25B5/00, F25B6/00, F25B7/00, F25B9/00 take precedence) · CPC title