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
  • F25D21/002—Defroster control
• • 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
• • 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
  • F25D2400/00—General features of, or devices for refrigerators, cold rooms, ice-boxes, or for cooling or freezing apparatus not covered by any other subclass
  • F25D2400/34—Temperature balancing devices
• • 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
  • F25D2700/00—Means for sensing or measuring; Sensors therefor
  • F25D2700/10—Sensors measuring the temperature of the evaporator
• • 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
  • F25D2700/00—Means for sensing or measuring; Sensors therefor
  • F25D2700/12—Sensors measuring the inside temperature
• • 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
  • F25D2700/00—Means for sensing or measuring; Sensors therefor
  • F25D2700/14—Sensors measuring the temperature outside the refrigerator or freezer

Definitions

• the present invention relates to a refrigerator with automatic defrost, also referred to as a no-frost refrigerator.
• Such refrigeration devices are e.g. used as household refrigerators or freezers.
• the evaporators of such refrigeration devices are equipped with heating devices which are operated from time to time in order to heat the evaporator to a temperature above 0.degree. C. and thus to melt frost, which is deposited on the evaporator during operation and the like Cooling performance affected.
• a temperature-dependent control of the automatic defrost system is also used.
• it is known to measure the evaporation temperature and the air temperature at the evaporator inlet or outlet of an evaporator through which air flows, and to trigger a defrost process whenever the difference between these two temperatures directly affects one initial value measured after a defrost process exceeds a predetermined percentage
• the object of the present invention is to provide a refrigeration device with automatic defrosting which also maintains a favorable time interval for the defrosting processes in the event of changes in the outside temperature or the desired temperature of the cooling space set by a user.
• a refrigeration device with a cooling space, an evaporator for a refrigerant arranged on the cooling space, a first sensor for detecting a temperature of the cooling space and a second sensor for detecting a temperature of the refrigerant, a heating device for the evaporator and a control device for operation of the heating device as a function of the temperatures measured by the two sensors, in that a third sensor is provided for detecting an outside temperature, and in that the control circuit is set up to activate the heating device if the temperature measured by the second sensor falls below a limit value , which is determined as a function of the temperatures measured by the first and third sensors.
• the control circuit can be implemented in a simple manner with a memory which records values of the limit value for different pairs of outside and cold room temperature.
• the control circuit can further comprise an interpolation unit for calculating the limit value for pairs of temperatures measured by the first and third sensors on the basis of the values recorded in the memory.
• the limit values for all pairs of outside and cold room temperature are preferably selected such that they correspond to a predetermined frost layer thickness on the evaporator. These values can be measured, for example, on a prototype of the refrigeration device under standardized operating conditions, and the limit values thus obtained are stored in the control devices of the refrigeration devices supplied by the manufacturer, According to a simple embodiment, these limit values can be predetermined, but it is also conceivable to design the control device in such a way that it is able to change these limit values
• the control device is preferably able to measure the time required by the heating device to defrost the evaporator and thus to draw a conclusion about the amount or layer of frost actually present on the evaporator if the time required for defrosting deviates from a desired value corresponding to the optimal amount of frost , the control device changes the limit values of the second sensor so that the time required for defrosting converges to the setpoint value. That is, if the defrost takes too long, the limit value of the temperature difference is reduced, if it does not last long enough, it is increased
• Such an adjustment of the limit values is preferably carried out selectively only for those limit values which are assigned to pairs of outside and cold room temperature which are only a short distance from the outside temperature-cold room temperature pair at which the defrosting time was measured.
• This selective readjustment acquires a cold device according to the invention during its operation a set of limit values of the second temperature sensor, which is adapted absolutely flexibly to the specific conditions of use of the cold device
• Fig. 1 is a highly schematic representation of a cold device according to the invention.
• FIG. 2 shows a flow chart of a control method carried out by the control device of the cold device
• FIG. 1 shows a highly schematic illustration of a cold device with an insulating housing 1, which encloses a cooling chamber 2. From a cold medium circuit of the cold device, an evaporator 3 inside the cooling room and a compressor 4 are shown in the figure, which evaporator 3 contains liquefied refrigerant supplied and extracted evaporated refrigerant therefrom
• a first sensor 5 is in the cold room for detection arranged from its temperature Ti.
• a second temperature sensor 6 is located on the evaporator 3 in the vicinity of the refrigerant inlet in order to measure the evaporating temperature T v of the refrigerant.
• a third sensor 7 for measuring the outside temperature T e is arranged outside the housing 1. All three sensors are connected to a control device, here a microprocessor 8.
• the microprocessor 8 regulates the operation of the compressor 4 on the basis of the temperature Ti measured by the first sensor 5, and it controls the operation of a heating element 9 arranged on the evaporator 3 on the basis of the temperatures measured by all three sensors 5, 6, 7 and a set of limit values, the memory 10 connected in another microprocessor 8 is stored.
• a first step S1 the microprocessor 8 detects the temperatures Ti of the interior, T e of the surroundings and T v of the evaporator measured by the sensors 5, 6, 7.
• step S2 he determines a limit value Tu ,, assigned to the measured values of T,, T e , of the evaporator temperature.
• This determination can be carried out, for example, by storing the microprocessor 8 among the pairs of inside and outside temperature for which a limit value is stored in the memory 10, which determines the one closest to the measured pair of inside and outside temperature and assumes its limit value as the assigned limit value. It is also conceivable to round the measured temperature values to the next higher or lower temperature value, for which a limit value is present in the memory 10.
• microprocessor 8 for a pair (T ,, T e ) of measured inside and outside temperatures those four pairs (Ti-, T e .), (Tj., T e + ), (T i + , T e .) and (Tj +, T e +) determined for the Tj.
• (T e .) Is the temperature value closest to T, (T e ) and T, + (T e + ) the temperature value next to T, (T e ), for which a limit value is stored in the memory 10, and that the Microprocessor sets the limit for (Ti, T e ) by interpolating the limits to (T,., T e .), (T,., T e + ), (T i + , T e .) And (T i + , T e + ) certainly,
• step S3 the found limit value T m is compared with the evaporator temperature T v . If the evaporator temperature is higher than the limit, it is concluded that defrosting is not yet necessary and the process returns to the beginning. If the evaporator temperature T v is lower than the limit value, it is assumed that a frost layer has formed on the evaporator which must be defrosted. As a result, the microprocessor 8 sets a timer to 0 in step S4 and starts supplying the heater 9 with power to defrost the evaporator 3.
• step S5 the power supply to the heating device 9 is interrupted and the microprocessor 8 reads out the timer in order to find out the duration t of the defrosting process (step S5).
• step S6 the duration t is compared with a first limit value. If the duration t is greater than this limit value liml, the limit value read from the memory 10 in step S2 is reduced in step S7. All other limit values in the memory remain unchanged. If t is smaller than the target value liml, a comparison of the time period t with a smaller target value Iim2 follows in step S8. If the time period t falls below this target value, the limit value Tii m determined in step S2 is increased in the memory 8 in step S9.
• steps S7 or S9 can be done by subtracting or adding a fixed, small positive value or by subtracting or adding a value proportional to the difference between t and the setpoint liml or Iim2.
• a reduction or enlargement by multiplying or dividing by a predetermined fixed factor or a factor proportional to the difference is also possible.
• becomes over time for each operating condition of the cold device defined by a pair (of an outside temperature T e and an inside or cold room temperature T 1) lm obtained for the evaporator temperature, which corresponds exactly to a predetermined target thickness of a frost layer on the evaporator 3, changes in the operating conditions, be it due to fluctuations in the outside temperature T e or because a user sets a changed cooling chamber temperature T between two defrosting processes can no longer cause problems in the Carry out the rhythm of the defrosting processes since the suitable evaporator limit temperature T v is stored as a limit value in the memory 10 for all combinations of these temperatures.
• the defrost control is therefore completely independent of time.
• the door of the cold appliance is not opened and no moisture can penetrate inside and frost can form on the evaporator. If the door remains open for a longer period of time and accordingly more moisture than usual penetrates into the appliance, defrosting will occur more often This does not entail a change in the behavior of the control, which could lead to an inappropriate control during subsequent normal operation

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• 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)
• Devices That Are Associated With Refrigeration Equipment (AREA)

Applications Claiming Priority (3)

Publications (2)

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Family Applications (1)

Country Status (7)

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Family Cites Families (8)

• 2000
  • 2000-10-27 DE DE10053422A patent/DE10053422A1/de not_active Withdrawn
• 2001
  • 2001-10-09 CN CN01818141.4A patent/CN1471622B/zh not_active Expired - Fee Related
  • 2001-10-09 ES ES01982413T patent/ES2266279T3/es not_active Expired - Lifetime
  • 2001-10-09 EP EP01982413A patent/EP1332325B1/fr not_active Expired - Lifetime
  • 2001-10-09 WO PCT/EP2001/011660 patent/WO2002035165A1/fr active IP Right Grant
  • 2001-10-09 BR BR0114956-3A patent/BR0114956A/pt not_active IP Right Cessation
  • 2001-10-09 AT AT01982413T patent/ATE329217T1/de not_active IP Right Cessation
  • 2001-10-09 DE DE50110072T patent/DE50110072D1/de not_active Expired - Lifetime

Non-Patent Citations (1)

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