US3744267A - Liquid level protection system for refrigeration compressor - Google Patents

Liquid level protection system for refrigeration compressor Download PDF

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Publication number
US3744267A
US3744267A US00234822A US3744267DA US3744267A US 3744267 A US3744267 A US 3744267A US 00234822 A US00234822 A US 00234822A US 3744267D A US3744267D A US 3744267DA US 3744267 A US3744267 A US 3744267A
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US
United States
Prior art keywords
coupled
semiconductor switch
circuit
thermistor
control circuit
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Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US00234822A
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English (en)
Inventor
D Norbeck
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
York International Corp
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Borg Warner Corp
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Publication of US3744267A publication Critical patent/US3744267A/en
Assigned to YORK INTERNATIONAL CORPORATION, 631 SOUTH RICHLAND AVENUE, YORK, PA 17403, A CORP. OF DE reassignment YORK INTERNATIONAL CORPORATION, 631 SOUTH RICHLAND AVENUE, YORK, PA 17403, A CORP. OF DE ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: BORG-WARNER CORPORATION
Assigned to CANADIAN IMPERIAL BANK OF COMMERCE reassignment CANADIAN IMPERIAL BANK OF COMMERCE SECURITY INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: YORK INTERNATIONAL CORPORATION
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Expired - Lifetime legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B49/00—Arrangement or mounting of control or safety devices
    • F25B49/02—Arrangement or mounting of control or safety devices for compression type machines, plants or systems
    • F25B49/022—Compressor control arrangements
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B49/00—Arrangement or mounting of control or safety devices
    • F25B49/005—Arrangement or mounting of control or safety devices of safety devices
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F23/00—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm
    • G01F23/22—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water
    • G01F23/24—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water by measuring variations of resistance of resistors due to contact with conductor fluid
    • G01F23/246—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water by measuring variations of resistance of resistors due to contact with conductor fluid thermal devices
    • G01F23/247—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water by measuring variations of resistance of resistors due to contact with conductor fluid thermal devices for discrete levels
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B2700/00—Sensing or detecting of parameters; Sensors therefor
    • F25B2700/04—Refrigerant level

Definitions

  • the thermistor has a negative temperature coefficient of resistivity and is mounted in a housing wall [52] U S C :4:g?b? a f i above the normal liquid level, where the liquid includes [51] Int. C] Fz'sb 47/00 at least some refrigerant.
  • the thermistor is connected [58] Field 85 192 in a circuit which is normally energized, so that the 62/l93 thermistor is self-energized and its impedance is low. If i 2 refrigerant accumulates and contacts the thermistor, the refrigerant boils off and rapidly cools the thermis- [56] References cued tor, increasing its impedance.
  • compressors are generally used to raise the temperature and pressure of the gaseous refrigerant before it enters the condensor to remove heat from the system.
  • a hermetic compressor generally has a motor in the upper portion of the housing, coupled over a shaft to the compressor itself in the lower portion of the housing. Oil can be contained in the bottom of the housing, where it contacts the shaft to provide lubrication for the driving system.
  • refrigerant enters the lower part of the housing and increases the liquid level, the liquid can enter the compressor cylinders and damage the compressor.
  • Various systems have been devised to protect against such a high liquid level condition in compressors (or in the receiver or other system component), but none has proved satisfactory.
  • Another important consideration of the invention is the provision of such a protective arrangement which is effective when the liquid level is excessive at the time the system is energized to prevent energization of the electric motor.
  • the present invention includes a control circuit for protecting a refrigeration system which includes an electric motor.
  • the system includes a housing for retaining liquid which has at least some refrigerant at a given level in its lower portion.
  • the control circuit includes a voltage divider circuit, having an impedance component coupled over a common terminal to an element which has a negative temperature coefficient of resistivity; this element is mounted in the housing above the given liquid level.
  • An a-c voltage is applied over a pair of conductors to the voltage divider circuit.
  • a rectifier is coupled to one of the conductors, and a d-c relay has its winding coupled between this rectifier and the other conductor.
  • the relay has a contact set connected to regulate power transfer to the electric motor.
  • FIG. 1 is a block diagram showing the incorporation of the control circuit of this invention with an energizing system for a motor-driven compressor;
  • FIG. 2 is a schematic diagram depicting details of the control circuit shown generally in FIG. 1.
  • FIG. 1 depicts a general arrangement for energizing a compressor 10.
  • Three phase a-c energy is received from a conventional power source (not shown) over lines 11a, 1 lb and 1 1c and applied to maintain controller 12.
  • Energy from one phase circuit is passed over line 13 to power control unit 14; of course line 13 represents two conductors but a single line is depicted for simplicity of explanation.
  • This energy is then passed over line 15 to compressor control circuit 16, which also receives a control signal over line 17.
  • This control signal can be a temperature-representative signal from a thermostat.
  • the output signal from control circuit 16 is passed over line 18 to a liquid level control circuit 20.
  • a thermistor 21 is positioned in the crankcase of compressor 10 above a reference level 4] representing the normal upper surface of the liquid 22, including oil and refrigerant. Under normal conditions the liquid level remains below the given level 41, when additional refrigerant does not leak down to increase the level of the refrigerant-andoil mixture.
  • the signal from thermistor 21 is applied over line 23 to liquid level control circuit 20.
  • the output signal from circuit 20 is passed over line 29 to controller 12. If the oil-refrigerant liquid rises above level 41, it represents a dangerous and undesired condition, in that liquid could enter the compressor cylinders and damage the compressor.
  • controller 12 When the liquid level in compressor 10 is below thermistor 21, controller 12 is effective to complete a circuit for passing electrical energy over lines 40a, 40b and 400 to energize motor 10a in the upper portion of the compressor assembly.
  • the liquid level control circuit 20 is not effective to energize and deenergize the compressor itself, but rather is in series with the signal from compressor control circuit 16 to regulate operation of controller 12.
  • thermistor element 21 is shown within control circuit 20 in FIG. 2, although physically it is mounted in the crankcase of compressor 10 as shown generally in FIG. 1. Electrically thermistor 21 is coupled over a common terminal 24 to an impedance component 25. Component 25 is shown as a resistor in FIG. 2, and with thermistor 21 forms a voltage divider circuit between a pair of conductors 18a, 18b over which the a-c voltage is applied to control circuit 20. Another series circuit between conductors 18a and 18b includes a thermostat 26, a diode 27, a resistor 28, and a relay winding 42. Relay winding 42 with its associated contact set 43 can be considered as a switching means for regulating de-energization of the compressor motor when the excess liquid level condition is detected.
  • Unit 31 is shown as a lightemitting diode (LED), because such units provide a visible indication of current flow and exhibit only a very small voltage drop, usually less than 2 volts.
  • LED lightemitting diode
  • Conventional indicator lamps (such as incandescent bulbs) which have a drop of several volts may not be workable in the circuit, ashe units 31, 32 must provide a virtural short circuit across winding 42 when switch 32 is turned on.
  • Switch 32 can be a silicon-controlledrectifier (SCR) or any other suitable switch with input, output and gate connections. Thev input and output connections are coupled in series with unit 31 as shown.
  • the gate connection of switch 32 is coupled over a series circuit including a resistor 33, a second semiconductor switch 34, a diode 35, and a resistor 45 to common terminal 24.
  • the second switch 34 can be another SCR, with its gate coupled over resistor 46 to conductor 18b.
  • a Zener diode 47 is coupled between the anode and the gate of second switch 34 as shown.
  • a resistor 36 is connected as shown between the oath ode of switch 34 and conductor 18b.
  • a capacitor 37 is coupled between resistor 45 and conductor 18b to complete an RC filter 45, 37 for protection against noise and other transients which might otherwise effect spurious triggering of SCR 32.
  • Another filter capacitor 38 is coupled between diode7 and line 18b to filter the d-c voltage provided by diode 27 for energizinghe d-c relay winding 42, and for maintaining first SCR 32 in the conducting state after it is gated on.
  • the thermistor is a self-heated unit; it can be considered a heater, radiating heat to the interior of the compressor crankcase. As the thermistor is heated, its effective resistance value is decreased, so that most of the potential across the voltage divider circuit appears across resistor 25. The potential across thermistor 21 is sufficiently low so that the positive excursions of the a-c voltage passing through diode 35 are not sufficient to pass any pulse through Zener diode 47 to the gate of SCR 34. With SCR 34 off, there is no drive to the gate of SCR 32,'relay windings 42 and 30 remain energized and contact set 44 is closed.
  • the boiling heat transfer, as the refrigerant contacts the thermistor, is very important. This provides a substantial impedance change and consequent large change in the signal voltage developed across the thermistor. This large change in the signal or control voltage is sufficient both to overcome any variations caused by changes in the ambient temperature, and to minimize voltage fluctuations caused by power supply variations.
  • thermostat switch 26 is momentarily opened to interrupt the current through SCR 32.
  • the dial of the thermostat can be turned to effect the circuit interruption.
  • Use of the switch in conjunction with the thermostat element is preferable because actuation of the switch does not change the room temperature setting on the thermostat.
  • the effective resistance of thermistor 21 will have reached a suitably low value when switch 26 is restored to the closed circuit condition so that there will be no gate drive to the SCR 34, and SCR 32 will be off.
  • relay winding 42 will again be energized to close contact set 43, energize winding 30 and complete the power transfer circuit for the compressor.
  • SCR 34 will immediately turn on SCR' 32 to prevent the operation of the compressor motor 100.
  • thermistor 21 is contacting the oil-and-refrigerant liquid and is being cooled.
  • a voltage divider circuit including an impedance component coupled over a common terminal to an element having a negative temperature coefficient of resistivity and mounted in said housing above said given level;
  • a d-c relay having a winding coupled between said rectifier and the other of said conductors, and having a contact set connected to regulate power transfer to the electric motor;
  • a first semiconductor switch having input, output, and gate connections, coupled in parallel with said relay winding
  • a filter capacitor coupled between said rectifier and said other conductor, for maintaining a d-c energizing voltage across the first semiconductor switch
  • circuit means including a second semiconductor switch, coupled between the gate connection of the first semiconductor switch and the common terminal in the voltage divider circuit, to provide a turnon signal for the first semiconductor switch as a function of an impedance change in said element signifying cooling as the refrigerant liquid contacts the element and boils off.
  • a voltage divider circuit including an impedance component coupled over a common terminal to a thermistor having a negative temperature coefficient of resistivity and mounted in the compressor housing above said given level;
  • a d-c relay having a winding coupled between said rectifier and the other of said conductors and having a contact set connected in the power transfer path for the electric motor;
  • a first semiconductor switch having input, output and gate connection, coupled in parallel with said relay winding to effectively short the relay winding when the semi-conductor switch is conducting;
  • a filter capacitor coupled between said rectifier and said other conductor, for maintaining a d-c energizing voltage across the first semiconductor switch and the d-c relay winding;
  • circuit means including a second semiconductor switch, coupled between said first semiconductor switch and the common terminal in the voltage divider circuit, to gate on the first semiconductor switch as the impedance of the thermistor increases to signify increased heat conduction by contact with the refrigerant.
  • a voltage divider circuit coupled between said pair of conductors, including a resistor coupled over a common terminal to a thermistor which has a negative temperature coefficient of resistivity, which thermistor is mounted in the compressor housing above said given level;
  • a series circuit coupled between said pair of conductors, including a rectifier and the winding of a d-c relay, so that a-c voltage supplied over the pair of conductors is rectified by the rectifier to energize the relay winding, which relay has a contact set connected in the power transfer path for the electric motor;
  • a first silicon controlled rectiifer having its anode and cathode connections coupled in parallel with the d-c relay winding, and having a gate connection;
  • a filter capacitor coupled in parallel with the anodecathode path of the first silicon controlled rectifier, and in parallel with the d-c relay winding, to maintain a d-c energizing voltage across these components;
  • a trigger circuit for said first silicon controlled rectifier coupled between its gate connection and the common terminal in the voltage divider circuit, comprising a diode and a second silicon controlled rectifier, to gate on the first silicon controlled rectifier as the impedance of the thermistor rises when refrigerant contacts the thermistor, boils off to cool the thermistor and thus increases its impedance.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Thermal Sciences (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Fluid Mechanics (AREA)
  • General Physics & Mathematics (AREA)
  • Control Of Positive-Displacement Pumps (AREA)
  • Compressor (AREA)
  • Measurement Of Levels Of Liquids Or Fluent Solid Materials (AREA)
  • Lubrication Details And Ventilation Of Internal Combustion Engines (AREA)
US00234822A 1972-03-15 1972-03-15 Liquid level protection system for refrigeration compressor Expired - Lifetime US3744267A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US23482272A 1972-03-15 1972-03-15

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US3744267A true US3744267A (en) 1973-07-10

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US (1) US3744267A (Sortimente)
JP (1) JPS5330364B2 (Sortimente)
AU (1) AU471560B2 (Sortimente)
CA (1) CA972855A (Sortimente)
DE (1) DE2311821C3 (Sortimente)
FR (1) FR2176125B1 (Sortimente)
GB (1) GB1389767A (Sortimente)
IT (1) IT981377B (Sortimente)

Cited By (24)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4004431A (en) * 1975-05-22 1977-01-25 The Johnson Corporation Control for cooling unit
DE2639019A1 (de) * 1976-08-30 1978-03-09 Danfoss As Kaeltemaschine
US4090371A (en) * 1975-11-24 1978-05-23 Technological Enterprises Corp. Monitor and control for refrigeration system
US4285207A (en) * 1978-07-31 1981-08-25 Diesel Kiki Company, Ltd. Air conditioning apparatus comprising refrigerant shortage sensor
US4794763A (en) * 1985-02-25 1989-01-03 Sanden Corporation Device for protecting a compressor from damage
EP0300866A1 (fr) * 1987-07-24 1989-01-25 L'unite Hermetique S.A. Motocompresseur hermétique
US5062277A (en) * 1990-10-29 1991-11-05 Carrier Corporation Combined oil heater and level sensor
US5253481A (en) * 1991-08-29 1993-10-19 Zexel Corporation Control unit for activating compressor
US5289692A (en) * 1993-01-19 1994-03-01 Parker-Hannifin Corporation Apparatus and method for mass flow control of a working fluid
US5335513A (en) * 1993-01-19 1994-08-09 Parker-Hannifin Corporation Apparatus and method for detecting characteristics of a working fluid
US5477701A (en) * 1993-01-19 1995-12-26 Parker-Hannifin Corporation Apparatus and method for mass flow control of a working fluid
US5660052A (en) * 1993-01-19 1997-08-26 Parker-Hannifin Corporation Apparatus and method for detecting characteristics of a working fluid
US5884494A (en) * 1997-09-05 1999-03-23 American Standard Inc. Oil flow protection scheme
US6091218A (en) * 1998-11-04 2000-07-18 Ritch; Harold D. Energy conservation circuit and method for use with multi-phase motors used to power a variable load
US6460354B2 (en) 2000-11-30 2002-10-08 Parker-Hannifin Corporation Method and apparatus for detecting low refrigerant charge
US20080000246A1 (en) * 2006-06-28 2008-01-03 Computime, Ltd. Conveying Temperature Information in a Controlled Variable Speed Heating, Ventilation, and Air Conditioning (HVAC) System
US20080250798A1 (en) * 2007-04-11 2008-10-16 American Standard International Inc Method for sensing the liquid level in a compressor
WO2016071947A1 (ja) * 2014-11-04 2016-05-12 三菱電機株式会社 冷凍サイクル装置及び冷凍サイクル装置の異常検知システム
US9851135B2 (en) * 2012-11-16 2017-12-26 Emerson Climate Technologies, Inc. Compressor crankcase heating control systems and methods
US9879894B2 (en) 2013-09-19 2018-01-30 Emerson Climate Technologies, Inc. Compressor crankcase heating control systems and methods
EP3246571A4 (en) * 2015-01-16 2018-06-20 Mitsubishi Electric Corporation Compressor
US10041487B2 (en) 2013-08-30 2018-08-07 Emerson Climate Technologies, Inc. Compressor assembly with liquid sensor
US10125768B2 (en) 2015-04-29 2018-11-13 Emerson Climate Technologies, Inc. Compressor having oil-level sensing system
CN114034140A (zh) * 2021-11-29 2022-02-11 四川虹美智能科技有限公司 化霜方法和装置

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4220041A (en) 1977-04-07 1980-09-02 Potter Bronson M Alien liquid detector and control

Cited By (39)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4004431A (en) * 1975-05-22 1977-01-25 The Johnson Corporation Control for cooling unit
US4090371A (en) * 1975-11-24 1978-05-23 Technological Enterprises Corp. Monitor and control for refrigeration system
DE2639019A1 (de) * 1976-08-30 1978-03-09 Danfoss As Kaeltemaschine
US4285207A (en) * 1978-07-31 1981-08-25 Diesel Kiki Company, Ltd. Air conditioning apparatus comprising refrigerant shortage sensor
US4794763A (en) * 1985-02-25 1989-01-03 Sanden Corporation Device for protecting a compressor from damage
AU589602B2 (en) * 1985-02-25 1989-10-19 Sanden Corporation Protecting device for compressor
EP0300866A1 (fr) * 1987-07-24 1989-01-25 L'unite Hermetique S.A. Motocompresseur hermétique
FR2618537A1 (fr) * 1987-07-24 1989-01-27 Unite Hermetique Sa Motocompresseur hermetique a securite amelioree
US5062277A (en) * 1990-10-29 1991-11-05 Carrier Corporation Combined oil heater and level sensor
US5253481A (en) * 1991-08-29 1993-10-19 Zexel Corporation Control unit for activating compressor
US5289692A (en) * 1993-01-19 1994-03-01 Parker-Hannifin Corporation Apparatus and method for mass flow control of a working fluid
US5335513A (en) * 1993-01-19 1994-08-09 Parker-Hannifin Corporation Apparatus and method for detecting characteristics of a working fluid
US5477701A (en) * 1993-01-19 1995-12-26 Parker-Hannifin Corporation Apparatus and method for mass flow control of a working fluid
US5522231A (en) * 1993-01-19 1996-06-04 Parker-Hannifin Corporation Apparatus and method for mass flow control of a working fluid
US5660052A (en) * 1993-01-19 1997-08-26 Parker-Hannifin Corporation Apparatus and method for detecting characteristics of a working fluid
US5884494A (en) * 1997-09-05 1999-03-23 American Standard Inc. Oil flow protection scheme
US6091218A (en) * 1998-11-04 2000-07-18 Ritch; Harold D. Energy conservation circuit and method for use with multi-phase motors used to power a variable load
US6460354B2 (en) 2000-11-30 2002-10-08 Parker-Hannifin Corporation Method and apparatus for detecting low refrigerant charge
US20080000246A1 (en) * 2006-06-28 2008-01-03 Computime, Ltd. Conveying Temperature Information in a Controlled Variable Speed Heating, Ventilation, and Air Conditioning (HVAC) System
US20080250798A1 (en) * 2007-04-11 2008-10-16 American Standard International Inc Method for sensing the liquid level in a compressor
US7874724B2 (en) 2007-04-11 2011-01-25 Trane International Inc. Method for sensing the liquid level in a compressor
US20110075700A1 (en) * 2007-04-11 2011-03-31 Okoren Ronald W Method for sensing a fluid in a compressor shell
US20110075699A1 (en) * 2007-04-11 2011-03-31 Okoren Ronald W Method for sensing a fluid in a compressor shell
US8393787B2 (en) 2007-04-11 2013-03-12 Trane International Inc. Method for sensing a fluid in a compressor shell
US8454229B2 (en) 2007-04-11 2013-06-04 Trane International Inc. Method for sensing a fluid in a compressor shell
US9851135B2 (en) * 2012-11-16 2017-12-26 Emerson Climate Technologies, Inc. Compressor crankcase heating control systems and methods
US10801764B2 (en) 2012-11-16 2020-10-13 Emerson Climate Technologies, Inc. Compressor crankcase heating control systems and methods
US10041487B2 (en) 2013-08-30 2018-08-07 Emerson Climate Technologies, Inc. Compressor assembly with liquid sensor
US9879894B2 (en) 2013-09-19 2018-01-30 Emerson Climate Technologies, Inc. Compressor crankcase heating control systems and methods
WO2016071947A1 (ja) * 2014-11-04 2016-05-12 三菱電機株式会社 冷凍サイクル装置及び冷凍サイクル装置の異常検知システム
JPWO2016071947A1 (ja) * 2014-11-04 2017-04-27 三菱電機株式会社 冷凍サイクル装置及び冷凍サイクル装置の異常検知システム
US20170268811A1 (en) * 2014-11-04 2017-09-21 Mitsubishi Electric Corporation Refrigeration cycle apparatus, and abnormality detection system for refrigeration cycle apparatus
US10161661B2 (en) * 2014-11-04 2018-12-25 Mitsubishi Electric Corporation Refrigeration cycle apparatus, and abnormality detection system for refrigeration cycle apparatus
GB2546657B (en) * 2014-11-04 2020-09-02 Mitsubishi Electric Corp Refrigeration cycle apparatus, and abnormality detection system for refrigeration cycle apparatus
GB2546657A (en) * 2014-11-04 2017-07-26 Mitsubishi Electric Corp Refrigeration cycle device and abnormality detection system for refrigeration cycle device
EP3246571A4 (en) * 2015-01-16 2018-06-20 Mitsubishi Electric Corporation Compressor
US10125768B2 (en) 2015-04-29 2018-11-13 Emerson Climate Technologies, Inc. Compressor having oil-level sensing system
US10180139B2 (en) 2015-04-29 2019-01-15 Emerson Climate Technologies, Inc. Compressor having oil-level sensing system
CN114034140A (zh) * 2021-11-29 2022-02-11 四川虹美智能科技有限公司 化霜方法和装置

Also Published As

Publication number Publication date
DE2311821B2 (de) 1979-01-11
DE2311821C3 (de) 1979-09-13
AU471560B2 (en) 1976-04-29
DE2311821A1 (de) 1973-10-04
IT981377B (it) 1974-10-10
FR2176125B1 (Sortimente) 1975-10-31
FR2176125A1 (Sortimente) 1973-10-26
GB1389767A (en) 1975-04-09
JPS48102307A (Sortimente) 1973-12-22
AU5272773A (en) 1974-08-29
JPS5330364B2 (Sortimente) 1978-08-26
CA972855A (en) 1975-08-12

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