EP0067523A1 - Vorrichtung zum Anzeigen von Frost - Google Patents

Vorrichtung zum Anzeigen von Frost Download PDF

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Publication number
EP0067523A1
EP0067523A1 EP82302383A EP82302383A EP0067523A1 EP 0067523 A1 EP0067523 A1 EP 0067523A1 EP 82302383 A EP82302383 A EP 82302383A EP 82302383 A EP82302383 A EP 82302383A EP 0067523 A1 EP0067523 A1 EP 0067523A1
Authority
EP
European Patent Office
Prior art keywords
resistor
frost
resistance
coil
heat pump
Prior art date
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.)
Withdrawn
Application number
EP82302383A
Other languages
English (en)
French (fr)
Inventor
Phillip D. Kruger
Ward J. Macarthur
Dale A. Mueller
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.)
Honeywell Inc
Original Assignee
Honeywell Inc
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Honeywell Inc filed Critical Honeywell Inc
Publication of EP0067523A1 publication Critical patent/EP0067523A1/de
Withdrawn legal-status Critical Current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
    • F25D—REFRIGERATORS; COLD ROOMS; ICE-BOXES; COOLING OR FREEZING APPARATUS NOT OTHERWISE PROVIDED FOR
    • F25D21/00—Defrosting; Preventing frosting; Removing condensed or defrost water
    • F25D21/02—Detecting the presence of frost or condensate

Definitions

  • This invention relates to frost sensing apparatus and has particular application in defrost control systems for refrigeration equipment.
  • apparatus for sensing the presence of frost on a refrigeration coil, said apparatus being characterized by an electrical resistor mounted on a surface of the coil, the resistor having a positive or negative temperature coefficient of resistance; and a control circuit including means periodically connecting the resistor to a source of electrical power for a fixed interval of time and means sensing the resistance of the resistor whereby to detect the magnitude of change of resistance during said time interval and hence the presence or not of frost on the coil.
  • the defrost control system 12 is connected to a power supply by conductors 13 and 14.
  • the system 12 is further connected in use by conductor 15 to a heat pump 16.
  • the heat pump 16 receives a defrost command on the conductor 15.
  • An electric resistor 20 is mounted on a refrigeration or evaporator coil of the heat pump 16, (indicated by dotted line 17), and is subject to becoming covered with frost or ice as the heat pump operates.
  • the evaporator coil typically is mounted external to the building to which the heat pump supplies heat.
  • the electric resistor 20 is also identified as R.
  • the electric resistor 20 would be a negative temperature coefficient resistor, but it could be a positive coefficient resistor.
  • the only requirement of the electric resistor is that it has a coefficient of resistance that is not zero. In other words, the resistor 20 must have a resistance value that changes positively or negatively as a change in temperature occurs.
  • the resistor 20 is connected by a pair of conductors 21 and 22 to a pair of terminals 23 and 24 which allow the interconnection of the resistor 20 to the defrost control system 12.
  • the connector 23 is directly connected to the supply line 13, while the connector 24 connects the conductor 22 to an analog to digital converter 25 that is included within the defrost control system 12.
  • the analog to digital converter 25 further receives power on conductor 26 from the conductor 13 along with a further power connection 27 which is connected to the ground conductor 14.
  • the analog to digital converter 25 is connected by a conductor 30 to the connector 24.
  • the resistance of the resistor 20 is capable of being measured at the analog to digital converter 25 and is supplied as a digital output signal on a group of conductors generally disclosed at 31.
  • the group of conductors 31 is connected at 32 to a microcomputer 33 which typically would be a microprocessor type of device.
  • the microcomputer 33 could be any type of analyzing circuitry, even in discrete component configuration, which is capable of providing functions which will be explained in connection with Figure 3 and the flow chart of Figure 4.
  • the microcomputer or microprocessor 33 is powered from conductors 34 and 35 which are in turn connected to the supply conductors 13 and 14. Only the functions of the microprocessor 33 which are directly related to the present invention have been disclosed and will be described. This microprocessor 33 could be similar to that disclosed in United States Patent No. 4,232,530. Only two outputs ports 36 and 37 from the microprocessor 33 are of interest in connection with the system disclosed in Figure 1, and they will be described in some detail. The output port 37 is connected to conductor 15 and supplies a defrost command signal from the microprocessor 33 to the heat pump 16 telling the heat pump to reverse its operation for a defrost cycle.
  • the output from port 36 is connected to a power control means 40.
  • the power control means 40 is specifically disclosed as a solid state switch having a pair of terminals 41 and 42 and a gate or control electrode 43. This control means could be an electromechanical relay.
  • the gate or control electrode 43 is connected to port 36 and is capable of receiving a gating signal to cause the power control means 40 to conduct between terminals 41 and 42.
  • the terminal 41 is connected to conductor 30, while the terminal 42 is connected to the group or conductor 14.
  • the control system 12 is completed by the addition of a resistor 44 that is connected across the power control means 40 and provides for the necessary voltage division for control and measuring of the resistor 20.
  • a curve 50 shows the resistance versus temperature characteristics of the electric resistor 20. This is a typical resistance versus temperature curve for a negative temperature coefficient resistance means. The significance of this curve and its application to the system of Figure 1 is explained in connection with Figure 3.
  • the power control means 40 is in a conduct mode thereby allowing energy to flow from the conductor 13 to the conductor 14 (and vice versa) through the power control means 40 and resistor 20. This allows the resistor 20 to heat along either of curves 51 or 52 disclosed in Figure 3 in dependence on the present or absent of frost on the evaporator coil.
  • the microprocessor 33 then provides a signal at port 36 to the gate 43 of the power control means 40 to operate the control means 40 to a nonconductive state. Power is then removed from the circuit directly connecting the resistor 20 across the conductors 13 and 14. With control means 40 in a nonconductive state, the analog to digital converter 25 provides a means of sensing the resistance between the conductors 26 and 30 through the interconnection 31 to the microprocessor 33.
  • the microprocessor 33 is capable of measuring the resistance and can determine whether the resistance of the resistor 20 is at point 55 of Figure 3 or is at 56 of Figure 3. With this arrangement, the microprocessor 33 obtains information as to whether or not frost or ice has built up on the resistor 20 to a point that requires defrosting. If such a defrost operation is necessary, the microprocessor 33 provides a signal at port 37 to the heat pump 16 indicating to the heat pump that a defrost cycle is to be undertaken.
  • the resistor 20 can supply continuous resistance information to the analog to digital converter 25 and then to the microcomputer means 33.
  • the microprocessor 33 can determine when the evaporator coil upon which the resistor 20 has been mounted has reached a high enough temperature to indicate that complete defrosting has occurred.
  • the temperature to which the coil would be raised is somewhere between 0 to 13 0 centigrade. The reason that the temperature of 13 0 Centigrade has been selected is to allow for an adequate period of time for water to run off of the coil upon which the resistor 20 is mounted.
  • the temperature indicated at the coil as measured by the resistor 20 is used to allow for the complete melting of any frost or ice, and for adequate run off of the defrost water.
  • the resistance 20 of Figure 1 along with the control circuit system 12 can directly determine the presence of frost or ice on the evaporator coil of a heat pump to cause the defrost cycle, and can be further extended to provide other functions.
  • Other functions that are readily available with this arrangement are the "permit” function and the "terminate” function.
  • the permit function determines if the evaporator coil is cold enough to be capable of collecting frost (that is, colder than 0° Centigrade).
  • the terminate function determines if the evaporator coil defrosting process is complete (that is, warmer than 0° Centigrade and generally up to some higher temperature to allow an adequate time for water run-off).
  • a flow chart shows a heat pump system.
  • the system is reset and then proceeds to determine whether the system is on or off. If the system is so on, the system then determines whether or not a time interval has been reached in which to measure the resistor 20 as indicated as the resistance R. If that time has been reached, the measurement of resistor 20 is accomplished. The resistor 20 is then checked to determine whether the resistor 20 is less than or equal to the "permit" temperature. If it is not, the mechanism is reset. If it is, the system energizes the power control means 40 for the time interval t. Deenergization of the resistor 20 occurs at the end of the time t, and the resistance of resistor 20 is again measured.
  • the system If no frost is present at this time, the system resets to measure a new time interval. If frost is present, the system waits for the resistor 20 to cool down to the temperature of the coil and its associated ice or frost. This prepares the resistor for the "terminate" function.
  • the microprocessor 33 commands a defrost cycle for the heat pump 16.
  • the function of the microprocessor 33 allows for a standard defrost cycle to proceed while measuring the resistor 20 to determine if R is greater than or equal to the "terminate" temperature. If it is not, the defrost cycle continues. When the terminate temperature is reached, it is indicative that the coil has been freed of frost or ice and has had time to drain. At this point the terminate function occurs and the defrost cycle is ended with the heat pump being put back into normal operation. The time increment measuring goes on to again measure for when frost or ice has built up on the refrigeration coil.

Landscapes

  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Physics & Mathematics (AREA)
  • Mechanical Engineering (AREA)
  • Thermal Sciences (AREA)
  • General Engineering & Computer Science (AREA)
  • Defrosting Systems (AREA)
EP82302383A 1981-05-28 1982-05-11 Vorrichtung zum Anzeigen von Frost Withdrawn EP0067523A1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US26731381A 1981-05-28 1981-05-28
US267313 1981-05-28

Publications (1)

Publication Number Publication Date
EP0067523A1 true EP0067523A1 (de) 1982-12-22

Family

ID=23018255

Family Applications (1)

Application Number Title Priority Date Filing Date
EP82302383A Withdrawn EP0067523A1 (de) 1981-05-28 1982-05-11 Vorrichtung zum Anzeigen von Frost

Country Status (2)

Country Link
EP (1) EP0067523A1 (de)
JP (1) JPS57198943A (de)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1985003135A1 (fr) * 1983-12-30 1985-07-18 Friedhelm Meyer Procede et sonde de mesure pour determiner la formation de glace ou de neige
EP0203669A1 (de) * 1985-05-30 1986-12-03 Koninklijke Philips Electronics N.V. Kühlschränke, insbesondere Haushaltskühlschränke
EP0315439A3 (de) * 1987-11-02 1990-09-19 The Coca-Cola Company Eisspeichersteuerungsverfahren für Getränkeausgabegerät
EP0644387A1 (de) * 1993-09-22 1995-03-22 IMI Cornelius Inc. Elektronisch gesteuerter Getränkespender
US5419461A (en) * 1992-08-26 1995-05-30 Imi Cornelius Inc. Flat carbonator for use with beverage dispenser
KR20010102639A (ko) * 2000-05-03 2001-11-16 김명희 중대형 건축구조물 지하용출수의 사이펀식 이송장치
CN115807983A (zh) * 2022-12-20 2023-03-17 珠海格力电器股份有限公司 空调机组

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3248892A (en) * 1963-02-25 1966-05-03 Texas Instruments Inc Refrigeration control regulating temperature and frost build-up
US4209994A (en) * 1978-10-24 1980-07-01 Honeywell Inc. Heat pump system defrost control
US4305259A (en) * 1980-04-03 1981-12-15 Eaton Corporation Frost sensor employing self-heating thermistor as sensor element

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3248892A (en) * 1963-02-25 1966-05-03 Texas Instruments Inc Refrigeration control regulating temperature and frost build-up
US4209994A (en) * 1978-10-24 1980-07-01 Honeywell Inc. Heat pump system defrost control
US4305259A (en) * 1980-04-03 1981-12-15 Eaton Corporation Frost sensor employing self-heating thermistor as sensor element

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1985003135A1 (fr) * 1983-12-30 1985-07-18 Friedhelm Meyer Procede et sonde de mesure pour determiner la formation de glace ou de neige
EP0203669A1 (de) * 1985-05-30 1986-12-03 Koninklijke Philips Electronics N.V. Kühlschränke, insbesondere Haushaltskühlschränke
EP0315439A3 (de) * 1987-11-02 1990-09-19 The Coca-Cola Company Eisspeichersteuerungsverfahren für Getränkeausgabegerät
AU617371B2 (en) * 1987-11-02 1991-11-28 Coca-Cola Company, The Ice bank control system for beverage dispenser
US5419461A (en) * 1992-08-26 1995-05-30 Imi Cornelius Inc. Flat carbonator for use with beverage dispenser
EP0644387A1 (de) * 1993-09-22 1995-03-22 IMI Cornelius Inc. Elektronisch gesteuerter Getränkespender
KR20010102639A (ko) * 2000-05-03 2001-11-16 김명희 중대형 건축구조물 지하용출수의 사이펀식 이송장치
CN115807983A (zh) * 2022-12-20 2023-03-17 珠海格力电器股份有限公司 空调机组

Also Published As

Publication number Publication date
JPS57198943A (en) 1982-12-06

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PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

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Effective date: 19831128

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Inventor name: MACARTHUR, WARD J.

Inventor name: MUELLER, DALE A.

Inventor name: KRUGER, PHILLIP D.