EP0117425B1 - Signal transmitter for controlling the defrosting process on the air side of the evaporator of a heat pump or the like - Google Patents

Signal transmitter for controlling the defrosting process on the air side of the evaporator of a heat pump or the like Download PDF

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Publication number
EP0117425B1
EP0117425B1 EP84100705A EP84100705A EP0117425B1 EP 0117425 B1 EP0117425 B1 EP 0117425B1 EP 84100705 A EP84100705 A EP 84100705A EP 84100705 A EP84100705 A EP 84100705A EP 0117425 B1 EP0117425 B1 EP 0117425B1
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EP
European Patent Office
Prior art keywords
console
sensing device
sensing
temperature
evaporator
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Expired
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EP84100705A
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German (de)
French (fr)
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EP0117425A1 (en
Inventor
Wilhelm Korsmeier
Klaus Klein
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EON Ruhrgas AG
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Ruhrgas AG
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Priority to AT84100705T priority Critical patent/ATE26170T1/en
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    • 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
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B2700/00—Sensing or detecting of parameters; Sensors therefor
    • F25B2700/11—Sensor to detect if defrost is necessary
    • F25B2700/111—Sensor to detect if defrost is necessary using an emitter and receiver, e.g. sensing by emitting light or other radiation and receiving reflection by a sensor

Definitions

  • the invention relates to a signal transmitter for controlling the defrosting process on the air side of the evaporator of a heat pump or the like with the features described in the preamble of claim 1.
  • a defrosting device is known in which a sensor block is placed directly on the evaporator surface and contains two temperature sensors, one of which contacts the evaporator surface and measures its temperature and the other temperature sensor at a distance from it Evaporator surface which measures the falling temperature of the ambient air in the vicinity of the evaporator with increasing icing. The defrosting process is initiated depending on the difference between these two measured temperatures.
  • an optical reflex sensor emitting a signal in the event of stronger light reflection is aligned directly with the evaporator surface and is closed solely with the signal emitted by the optical reflex sensor from the presence of a layer of frost on the evaporator surface and the defrosting process is initiated.
  • the defrosting process initiated by the optical reflex sensor is completed with a thermostat that has a sensing element attached in the cooling pipe system of the cooling machine and that controls the normal function of the cooling machine between the defrosting processes.
  • a defrosting device is known from WO 83/00 211, in which a thermostat switch which responds to the temperature in the vicinity of the evaporator is heated by an electric heating element in order to switch on the power supply to the compressor of the refrigeration machine and to switch off the power supply to electrically defrost the evaporator .
  • the defrosting process is initiated by a trigger signal, which can be the signal of an optical reflex sensor alone or in conjunction with another temperature-independent signal, for example a timer.
  • the trigger signal switches off the electric heater, so that the thermostat switch, which then cools under the influence of the ambient temperature of the evaporator, switches off the power supply to the compressor and switches on the power supply to the electrical defrost heater of the evaporator.
  • the defrosting process is ended by the fact that the ambient temperature of the evaporator, which rises under the influence of the electrical defrosting heater, resets the thermostat switch to the starting position in which the power supply to the compressor is switched on and the power supply to the defrosting heater the evaporator is switched off.
  • the initiation of the defrosting process only with temperature sensors and depending solely on the surface temperature or ambient temperature of the evaporator and whether a set temperature threshold value below which icing could occur is not sufficiently satisfactory and reliable.
  • the optical reflective sensor can already result of milky turbid condensed water in a not yet leading to icing below the dew - can occur punk limit, deliver a signal and thereby initiate an unnecessary, the normal operation of the refrigerating machine unnecessarily disturbing and interrupting defrosting.
  • the object of the invention is therefore to find a solution with which the defrosting process can be reliably initiated when a risk of icing to be eliminated or when a frost layer to be removed arises and with which the defrosting process can also be reliably ended when the frost layer has been defrosted.
  • a signal transmitter of the type mentioned this object is achieved according to the invention by the features listed in the characterizing part of patent claim 1. With this signal transmitter, the temperature receiver of the temperature sensor measuring the evaporator surface temperature and the optical reflex signal of the optical reflex sensor monitoring the auxiliary reflective surface are fed to the signal receiver for the AND link for the initiation and termination of the defrosting process.
  • the defrosting process is only initiated when, in addition to signaling the temperature sensor via an evaporator temperature with the possibility of icing, there is also signaling from the optical reflex sensor about the presence of a layer of frost or ice, or when in addition to a signal from the optical reflex sensor which instead of a reflective white icing layer on the auxiliary reflex surface can also be caused by a whitish, cloudy condensation layer, there is also a signal from the temperature sensor that a low evaporator temperature leading to icing is present.
  • the defrosting process is only ended when the temperature signal from the temperature sensor and the reflex signal from the optical reflex sensor are canceled in the defrosting phase, i.e. when the frost layer has thawed and the evaporator surface temperature has risen to such an extent that ice or frost can no longer be present.
  • the signal generator shown contains a bracket 1 that can be attached to the evaporator and is made of heat-conducting material, for example copper, and a sensor block 2 attached to the bracket, preferably made of plastic.
  • the sensor block 2 contains embedded a temperature sensor 3, which touches the console in a heat-conducting manner, and an optical reflex sensor 4, which emits light and responds to the reflection of light by an emerging frost layer.
  • the signal lines 5 of both sensors are led out of the sensor block 2 in a moisture-tight manner and can be connected to a signal receiver.
  • the console 1 is plate-shaped, so that the console can be inserted into an air gap 6 between two evaporator fins 7.
  • the console 1 For simple attachment of the signal transmitter to the evaporator, the console 1 has a trapezoidal shape, so that opposite plate edges 9 run in a wedge shape with respect to one another and the console with these plate edges can be inserted in a clamping manner between two evaporator tubes 10. At least along a plate edge 9, the console 1 has break-off perforations 11 in a row or in several rows, so that the plate width between the wedge-shaped plate edges 9 can be adapted to larger differences in the distance between the evaporator tubes 10 by breaking off edge strips.
  • the temperature sensor 3 measures both the temperature of the air flowing through the evaporator and the surface temperature of the evaporator via the console 1.
  • the console 1 contains an auxiliary reflective surface 12 on which a frost layer likewise forms when the evaporator is iced up.
  • the reflex sensor 4 is aligned with this optical axis on this auxiliary reflex surface 12.
  • the auxiliary reflective surface 12 is formed on its surface facing the reflex sensor 4 matt black, so that no light reflection and therefore no output signal of the reflex sensor occurs if no white, highly reflective frost formation has occurred or if a transparent liquid condensation has occurred on the matt black surface flows off itself from the auxiliary reflex surface 12 and does not require defrost initiation.
  • the auxiliary reflecting surface 12 In order to promote the dripping of water from the auxiliary reflecting surface 12 which runs vertically in the installed state, the auxiliary reflecting surface 12 has a water drainage tip 13 which, in the installed state, is directed downwards at its lower edge Degree twisted position is applied. Furthermore, the auxiliary reflecting surface 12 has a reflecting point 14 which is curved toward the sensor block 2 and around which the water flows to the water outlet tip 13, so that the reflecting point 14 remains largely without a water film and reflects as little light as possible.
  • the design of the console 1 as a plate has the advantage that the signal transmitter by inserting the console between evaporator fins and clamping between evaporator tubes can be conveniently arranged at those points, for example on the suction side of the evaporator, where, depending on the type and flow of the evaporator Experience has shown that icing or frost formation, which disturbs the refrigeration cycle, is most likely to occur. If the surface temperature of the evaporator determined by the temperature sensor 3 via the console 1 drops below a set temperature threshold value at which a risk of icing can begin, the temperature sensor generates a first signal in the defrosting device.
  • a switching delay of the defrosting device can preferably be provided so that a short-term drop below the temperature threshold value and exceeding the light reflection threshold value does not yet lead to an initiation of the defrosting process.
  • a switching delay can also be provided for the termination of the defrosting process after the temperature and reflection signals have been canceled.
  • the formation of a frost layer by means of the reflex sensor can also be monitored in pulse mode if continuous operation of the light emitting diode of the reflex sensor is not desired.
  • the type of icing of evaporators is strongly influenced by the state of the outside air.
  • the ice layer on the evaporator can be found in a color range from transparent (ice partly with water) to white.
  • the reflex sensor must recognize this area.
  • the reflex sensor should not only evaluate the degree of reflection, but also the reflection distance in order to detect the ice layer thicknesses. From these conditions it can be seen that the reflex sensor cannot always provide the correct signal without additional information.
  • the signal of the Reflex sensor clearly assigned to the state of the evaporator.
  • the signal from the reflex sensor means the presence of icing at low temperatures and the presence of water at positive temperatures.
  • the temperature is a maximum of 0 ° C. Only when the temperature sensor reaches positive temperatures, the ice has melted and the defrosting process can then be ended at the right time.
  • the AND linkage of both signals is an important feature of the signal generator or defrost sensor.
  • the thickness of the ice layer is also determined with the reflex sensor.
  • the reflex sensor advantageously works in the infrared range and is clocked and a suitable light filter is arranged in front of the reflex sensor, which shields the reflex sensor against interfering light such as daylight or fluorescent lamps and thereby eliminates false influences of the reflex sensor by interfering light.

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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)
  • Investigating Or Analyzing Materials By The Use Of Fluid Adsorption Or Reactions (AREA)

Abstract

1. A signal transmitter arrangement for controlling the defrosing of the air side of an evaporator means of a heat pump or the like comprising a sensing assembly consisting of a temperature sensing device for measuring the temperature on the surface of said evaporator means and a sensing device responding to the formation of frost or ice, said two sensing devices being coupled to a receiver for the transmission of signals, wherein said signal transmittal arrangement comprises a thermally conductive console (1) attachable to said evaporator means to which said sensing assembly (2) is connected, said temperature sensing device (3) being connected with said sensing assembly in a thermally conductive fashing, and wherein said sensing assembly comprises a photosensitive sensing device (4) constituting the second sensing device the optic axis of said photosensitive sensing device being aligned to an auxiliary matte black reflective surface (12) arranged vertically on said console, said reflective surface having a circular area of reflection (14) convex relative to said sensing assembly (2).

Description

Die Erfindung betrifft einen Signalgeber zur Steuerung des Abtauvorganges an der Luftseite des Verdampfers einer Wärmepumpe oder dergleichen mit den im Oberbegriff des Patentanspruchs 1 beschriebenen Merkmalen.The invention relates to a signal transmitter for controlling the defrosting process on the air side of the evaporator of a heat pump or the like with the features described in the preamble of claim 1.

Aus der GB-A-2 068 100 ist eine Abtaueinrichtung bekannt, bei der ein Sensorblock direkt auf die Verdampferoberfläche aufgesetzt ist und zwei Temperatursensoren enthält, von denen ein Temperatursensor an der Verdampferoberfläche anliegt und deren Temperatur mißt und der andere Temperatursensor in einem Abstand von der Verdampferoberfläche die bei zunehmender Vereisung sinkende Temperatur der Umgebungsluft in der Nähe des Verdampfers mißt. In Abhängigkeit von der Differenz dieser beiden gemessenen Temperaturen wird der Abtauvorgang eingeleitet. Bei der aus der DE-A-2453140 bekannten Abtaueinrichtung ist ein bei stärkerer Lichtreflexion ein Signal abgebender optischer Reflexsensor direkt auf die Verdampferoberfläche ausgerichtet und wird allein mit dem vom optischen Reflexsensor abgegebenen Signal aus das Vorhandensein einer Reifschicht auf der Verdampferoberfläche geschlossen und der Abtauvorgang eingeleitet. Mit einem Thermostaten, der ein im Kühlrohrsystem der Kältemaschine angebrachtes Fühlglied hat und der die Normalfunktion der Kältemaschine zwischen den Abtauvorgängen steuert, wird der vom optischen Reflexsensor eingeleitete Abtauvorgang abgeschlossen. Aus der WO 83/00 211 ist eine Abtaueinrichtung bekannt, bei der ein auf die Temperatur in der Umgebung des Verdampfers ansprechender Thermostatschalter von einem elektrischen Heizkörper erwämt wird, um die Stromzufuhr zum Kompressor der Kältemaschine einzuschalten und die Stromzufuhr zu einer elektrischen Abtauheizung des Verdampfers abzuschalten. Die Einleitung des Abtauvorganges erfolgt durch ein Auslösesignal, welches das Signal eines optischen Reflexsensors allein oder in Verbindung mit einem anderen temperaturunabhängigen Signal zum Beispiel einer Zeitschaltuhr sein kann. Das Auslösesignal schaltet den elektrischen Heizkörper ab, so daß der dann unter dem Einfluß der Umgebungstemperatur des Verdampfers sich abkühlende Thermostatschalter die Stromzufuhr zum Kompressor abschaltet und die Stromzufuhr zu der elektrischen Abtauhe9- zung des Verdampfers einschaltet. Unabhängig davon, ob das Auslösesignal aufgehoben ist oder nicht, erfolgt die Beendigung des Abtauvorganges dadurch, daß die unter der Einwirkung der elektrischen Abtauheizung ansteigende Umgebungstemperatur des Verdampfers den Thermostatschalter in die Ausgangsstellung zurückstellt, in der die Stromzufuhr zum Kompressor eingeschaltet und die Stromzufuhr zu der Abtauheizung des Verdampfers abgeschaltet ist. Die Einleitung des Abtauvorganges nur mit Temperatursensoren und in Abhängigkeit allein davon, welche Oberflächentemperatur oder Umgebungstemperatur der Verdampfer hat und ob ein eingestellter Temperaturschwellenwert, bei dem eine Vereisung vorkommen könnte, unterschritten wird, ist nicht genügend befriedigend und zuverlässig. Wenn auf der Luftseite des Verdampfers der Taupunkt und ein dazu angepaßter Temperaturschwellenwert unterschritten wird, muß nicht sogleich schon eine den Wärmeübergang an der Verdampferoberfläche verschlechternde Reifschicht beziehungsweise Vereisung entstehen, sondern kann zunächst nur ein Kondenswasserschicht entstehen, die von selbst abfließt und keinen Abtauvorgang erfordert, der den Wärmepumpenbetrieb unnötig unterbrechen würde. Andererseits könnte bei zu niedrig eingestelltem Temperaturschwellenwert vor dessen Unterschreitung bereits eine Reifschicht entstanden sein, die den Wärmeübergang schon erheblich verschlechtert, und könnte der notwendige Abtauvorgang zu spät einsetzen. Ebenfalls ist die Einleitung des Abtauvorganges mit einem optischen Reflexsensor, auch bei Verknüpfung mit einem anderen gänzlich temperaturunabhängigen Signal, nicht genügend befriedigend und zuverlässig. Der optische Reflexsensor kann bereits aufgrund von milchig trübem Kondenswasser, das bei einem noch nicht zu einer Vereisung führenden Unterschreiten der Tau- punksgrenze auftreten kann, ein Signal abgeben und dadurch einen nicht erforderlichen, den Normalbetrieb der Kältemaschine unnötig störenden und unterbrechenden Abtauvorgang einleiten.From GB-A-2 068 100 a defrosting device is known in which a sensor block is placed directly on the evaporator surface and contains two temperature sensors, one of which contacts the evaporator surface and measures its temperature and the other temperature sensor at a distance from it Evaporator surface which measures the falling temperature of the ambient air in the vicinity of the evaporator with increasing icing. The defrosting process is initiated depending on the difference between these two measured temperatures. In the defrosting device known from DE-A-2453140, an optical reflex sensor emitting a signal in the event of stronger light reflection is aligned directly with the evaporator surface and is closed solely with the signal emitted by the optical reflex sensor from the presence of a layer of frost on the evaporator surface and the defrosting process is initiated. The defrosting process initiated by the optical reflex sensor is completed with a thermostat that has a sensing element attached in the cooling pipe system of the cooling machine and that controls the normal function of the cooling machine between the defrosting processes. A defrosting device is known from WO 83/00 211, in which a thermostat switch which responds to the temperature in the vicinity of the evaporator is heated by an electric heating element in order to switch on the power supply to the compressor of the refrigeration machine and to switch off the power supply to electrically defrost the evaporator . The defrosting process is initiated by a trigger signal, which can be the signal of an optical reflex sensor alone or in conjunction with another temperature-independent signal, for example a timer. The trigger signal switches off the electric heater, so that the thermostat switch, which then cools under the influence of the ambient temperature of the evaporator, switches off the power supply to the compressor and switches on the power supply to the electrical defrost heater of the evaporator. Regardless of whether the trigger signal is canceled or not, the defrosting process is ended by the fact that the ambient temperature of the evaporator, which rises under the influence of the electrical defrosting heater, resets the thermostat switch to the starting position in which the power supply to the compressor is switched on and the power supply to the defrosting heater the evaporator is switched off. The initiation of the defrosting process only with temperature sensors and depending solely on the surface temperature or ambient temperature of the evaporator and whether a set temperature threshold value below which icing could occur is not sufficiently satisfactory and reliable. If the dew point and an adapted temperature threshold value on the air side of the evaporator are not reached, a layer of frost or icing that worsens the heat transfer on the surface of the evaporator does not have to be created immediately, but rather only a layer of condensed water that flows off by itself and does not require a defrosting process that requires would unnecessarily interrupt heat pump operation. On the other hand, if the temperature threshold is set too low, a frost layer could already have formed before it was fallen below, which would already considerably impair the heat transfer, and the necessary defrosting process could start too late. Likewise, initiating the defrosting process with an optical reflex sensor, even when linked to another signal that is completely independent of temperature, is not sufficiently satisfactory and reliable. The optical reflective sensor can already result of milky turbid condensed water in a not yet leading to icing below the dew - can occur punk limit, deliver a signal and thereby initiate an unnecessary, the normal operation of the refrigerating machine unnecessarily disturbing and interrupting defrosting.

Die Erfindung hat daher zur Aufgabe, eine Lösung zu finden, mit der der Abtauvorgang zuverlässig beim Auftreten einer zu beseitigenden Vereisungsgefahr beziehungsweise beim Entstehen einer zu entfernenden Reifschicht eingeleitet werden kann und mit der der Abtauvorgang auch zuverlässig bei erfolgtem Abtauen der Reifschicht beendet werden kann. Ausgehend von einem Signalgeber der eingangs genannten Art wird diese Aufgabe erfindungsgemäß durch die im Kennzeichen des Patentanspruchs 1 aufgeführten Merkmale gelöst. Mit diesem Signalgeber werden dem Signalempfänger zur UND-Verknüpfung für die Einleitung und Beendigung des Abtauvorganges das Temperatursignal des die Verdampferoberflächentemperatur messenden Temperatursensors und das optische Reflexsignal des die Hilfsreflexfläche überwachenden optischen Reflexsensors zugeführt. Dadurch erfolgt eine Einleitung des Abtauvorganges erst dann, wenn zusätzlich zu der Signalgabe des Temperatursensors über eine Verdampfertemperatur mit der Möglichkeit einer Vereisung auch noch eine Signalgabe des optischen Reflexsensors über das Vorhandensein einer Reif- oder Eisschicht vorliegt, oder wenn zusätzlich zu einem Signal des optischen Reflexsensors, welches anstatt durch eine reflektierende weiße Vereisungsschicht auf der Hilfsreflexfläche auch durch ein weißlich trübe Kondenswasserschicht hervorgerufen sein kann, auch noch ein Signal des Temperatursensors über eine zu einer Vereisung führende niedrige Verdampfertemperatur vorliegt. Analog wird der Abtauvorgang erst beendet, wenn in der Abtauphase das Temperatursignal des Temperatursensor und das Reflexsignal des optischen Reflexsensors aufgehoben sind, das heißt wenn die Reifschicht abgetaut ist und die Verdampferoberflächentemperatur so weit angestiegen ist, daß kein Eis oder Reif mehr vorhanden sein kann.The object of the invention is therefore to find a solution with which the defrosting process can be reliably initiated when a risk of icing to be eliminated or when a frost layer to be removed arises and with which the defrosting process can also be reliably ended when the frost layer has been defrosted. Starting from a signal transmitter of the type mentioned, this object is achieved according to the invention by the features listed in the characterizing part of patent claim 1. With this signal transmitter, the temperature receiver of the temperature sensor measuring the evaporator surface temperature and the optical reflex signal of the optical reflex sensor monitoring the auxiliary reflective surface are fed to the signal receiver for the AND link for the initiation and termination of the defrosting process. As a result, the defrosting process is only initiated when, in addition to signaling the temperature sensor via an evaporator temperature with the possibility of icing, there is also signaling from the optical reflex sensor about the presence of a layer of frost or ice, or when in addition to a signal from the optical reflex sensor which instead of a reflective white icing layer on the auxiliary reflex surface can also be caused by a whitish, cloudy condensation layer, there is also a signal from the temperature sensor that a low evaporator temperature leading to icing is present. Similarly, the defrosting process is only ended when the temperature signal from the temperature sensor and the reflex signal from the optical reflex sensor are canceled in the defrosting phase, i.e. when the frost layer has thawed and the evaporator surface temperature has risen to such an extent that ice or frost can no longer be present.

In der Zeichnung ist ein Ausführungsbeispiel des Signalgebers nach der Erfindung dargestellt, und zwar zeigt

  • Figur 1 den Signalgeber in perspektivischer Darstellung,
  • Figur 2 den in einen Verdampfer eingesetzten Signalgeber der Figur 1 in der Ansicht von unten.
In the drawing, an embodiment of the signal generator according to the invention is shown, namely shows
  • FIG. 1 shows the signal transmitter in a perspective view,
  • Figure 2 shows the signal transmitter used in an evaporator of Figure 1 in the view from below.

Der dargestellte Signalgeber enthält eine am Verdampfer befestigbare Konsole 1 aus wärmeleitendem Material, zum Beispiel Kupfer, und einen an der Konsole angebrachten Sensorblock 2 vorzugsweise aus Kunststoff. Der Sensorblock 2 enthält eingebettet einen Temperatursensor 3, der wärmeleitend die Konsole berührt, und einen optischen Reflexsensor 4, der Licht aussendet und auf die Lichtreflexion durch eine entstehende Reifschicht anspricht. Die Signalleitungen 5 beider Sensoren sind feuchtigkeitsdicht aus dem Sensorblock 2 herausgeführt und mit einem Signalempfänger verbindbar. Die Konsole 1 ist plattenförmig ausgebildet, so daß die Konsole in einen Luftspalt 6 zwischen zwei Verdampferlamellen 7 einführbar ist. Zur einfachen Befestigung des Signalgebers an dem Verdampfer hat die Konsole 1 eine Trapezform, so daß gegenüberliegende Plattenränder 9 keilförmig zueinander verlaufen und die Konsole mit diesen Plattenrändern zwischen zwei Verdampferröhren 10 klemmend eingesteckt werden kann. Wenigstens längs eines Plattenrandes 9 besitzt die Konsole 1 Abbrechperforationen 11 in einer Reihe oder in mehreren Reihen, so daß sich die Plattenbreite zwischen den keilförmig zueinander verlaufenden Plattenrändern 9 durch Abbrechen von Randstreifen an größere Unterschiede des Abstandes zwischen den Verdampferröhren 10 anpassen läßt. Über die Konsole 1 wird vom Temperatursensor 3 sowohl die Temperatur der den Verdampfer durchströmenden Luft als auch die Oberflächentemperatur des Verdampfers gemessen. Die Konsole 1 enthält eine Hilfsreflexfläche 12, auf der sich bei einer Vereisung des Verdampfers ebenfalls eine Reifschicht bildet. Auf diese Hilfsreflexfläche 12 ist der Reflexsensor 4 mit seiner optischen Achse ausgerichtet. Die Hilfsreflexfläche 12 ist auf ihrer dem Reflexsensor 4 zugekehrten Oberfläche mattschwarz ausgebildet, damit keine Lichtreflexion und somit auch kein Ausgangssignal des Reflexsensors auftritt, wenn noch keine weiße, stark reflektierende Reifbildung eingetreten ist oder wenn erst auf dem mattschwarzen Untergrund ein durchsichtiger flüssiger Kondensniederschlag vorliegt, der von selbst von der Hilfsreflexfläche 12 abfließt und keine Abtaueinleitung erfordert. Um das Abtropfen von Wasser von der im Einbauzustand vertikal verlaufenden Hilfsreflexfläche 12 zu fördern, hat die Hilfsreflexfläche 12 eine im Einbauzustand an ihrer Unterkante abwärts gerichtete Wasserablaufspitze 13. Eine zusätzlich vorgesehene, horizontal gerichtete weitere Wasserablaufspitze verbessert das Abtropfen, wenn der Signalgeber in einer um 90 Grad verdrehten Position angewendet wird. Ferner besitzt die Hilfsreflexfläche 12 einen zu Sensorblock 2 hin gewölbt ausgebildeten Reflexpunkt 14, um den herum das Wasser zur Wasserablaufspitze 13 fließt, so daß der Reflexpunkt 14 weitgehend ohne Wasserfilm bleibt und möglichst wenig Licht reflektiert.The signal generator shown contains a bracket 1 that can be attached to the evaporator and is made of heat-conducting material, for example copper, and a sensor block 2 attached to the bracket, preferably made of plastic. The sensor block 2 contains embedded a temperature sensor 3, which touches the console in a heat-conducting manner, and an optical reflex sensor 4, which emits light and responds to the reflection of light by an emerging frost layer. The signal lines 5 of both sensors are led out of the sensor block 2 in a moisture-tight manner and can be connected to a signal receiver. The console 1 is plate-shaped, so that the console can be inserted into an air gap 6 between two evaporator fins 7. For simple attachment of the signal transmitter to the evaporator, the console 1 has a trapezoidal shape, so that opposite plate edges 9 run in a wedge shape with respect to one another and the console with these plate edges can be inserted in a clamping manner between two evaporator tubes 10. At least along a plate edge 9, the console 1 has break-off perforations 11 in a row or in several rows, so that the plate width between the wedge-shaped plate edges 9 can be adapted to larger differences in the distance between the evaporator tubes 10 by breaking off edge strips. The temperature sensor 3 measures both the temperature of the air flowing through the evaporator and the surface temperature of the evaporator via the console 1. The console 1 contains an auxiliary reflective surface 12 on which a frost layer likewise forms when the evaporator is iced up. The reflex sensor 4 is aligned with this optical axis on this auxiliary reflex surface 12. The auxiliary reflective surface 12 is formed on its surface facing the reflex sensor 4 matt black, so that no light reflection and therefore no output signal of the reflex sensor occurs if no white, highly reflective frost formation has occurred or if a transparent liquid condensation has occurred on the matt black surface flows off itself from the auxiliary reflex surface 12 and does not require defrost initiation. In order to promote the dripping of water from the auxiliary reflecting surface 12 which runs vertically in the installed state, the auxiliary reflecting surface 12 has a water drainage tip 13 which, in the installed state, is directed downwards at its lower edge Degree twisted position is applied. Furthermore, the auxiliary reflecting surface 12 has a reflecting point 14 which is curved toward the sensor block 2 and around which the water flows to the water outlet tip 13, so that the reflecting point 14 remains largely without a water film and reflects as little light as possible.

Die Ausbildung der Konsole 1 als Platte hat den Vorzug, daß der Signalgeber durch Einführen der Konsole zwischen Verdampferlamellen und Einklemmen zwischen Verdampferröhren bequem an denjenigen Stellen, zum Beispiel an der Ansaugseite des Verdampfers, angeordnet werden kann, an denen je nach Art und Durchströmung des Verdampfers erfahrungsgemäß am ehesten eine den Kältekreislauf störende Vereisung beziehungsweise Reifbildung auftritt. Sinkt die vom Temperatursensor 3 über die Konsole 1 festgestellte Oberflächentemperatur des Verdampfers unter einen eingestellten Temperaturschwellenwert ab, bei dem eine Vereisungsgefahr beginnen kann, entsteht in der Abtausteuerungseinrichtung durch den Temperatursensor ein erstes Signal. Erst wenn der Reflexsensor 4 auf eine an der Hilfsreflexfläche 12 entstehende, reflektierende Reifschicht anspricht und ein zweites Signal erzeugt, wird der Abtauvorgang eingeleitet. Hierbei kann vorzugsweise eine Schaltverzögerung der Abtausteuerungseinrichtung vorgesehen sein, damit eine kurzfristige Unterschreitung des Temperaturschwellenwertes und Überschreitung des Lichtreflexionsschwellenwerter noch nicht zu einer Einleitung des Abtauvorganges führen. Gleichartig kann auch für die Beendigung des Abtauvorganges nach Aufhebung des Temperatur- und des Reflexionssignals eine Schaltverzögerung vorgesehen werden. Die Überwachung einer Reifschichtbildung mittels des Reflexsensors kann auch im Impulsbetrieb stattfinden, falls ein Dauerbetrieb der Lichtsendediode des Reflexsensors nicht gewünscht wird.The design of the console 1 as a plate has the advantage that the signal transmitter by inserting the console between evaporator fins and clamping between evaporator tubes can be conveniently arranged at those points, for example on the suction side of the evaporator, where, depending on the type and flow of the evaporator Experience has shown that icing or frost formation, which disturbs the refrigeration cycle, is most likely to occur. If the surface temperature of the evaporator determined by the temperature sensor 3 via the console 1 drops below a set temperature threshold value at which a risk of icing can begin, the temperature sensor generates a first signal in the defrosting device. Only when the reflex sensor 4 responds to a reflective layer of frost arising on the auxiliary reflective surface 12 and generates a second signal, is the defrosting process initiated. In this case, a switching delay of the defrosting device can preferably be provided so that a short-term drop below the temperature threshold value and exceeding the light reflection threshold value does not yet lead to an initiation of the defrosting process. Similarly, a switching delay can also be provided for the termination of the defrosting process after the temperature and reflection signals have been canceled. The formation of a frost layer by means of the reflex sensor can also be monitored in pulse mode if continuous operation of the light emitting diode of the reflex sensor is not desired.

Die Art der Vereisung von Verdampfern wird stark von dem jeweiligen Zustand der Außenluft beeinflußt. Die Eisschicht am Verdampfer ist in einem Farbbereich von transparent (Eis zum Teil mit Wasser) bis weiß anzutreffen. Diesen Bereich muß der Reflexsensor erkennen. Ferner soll der Reflexsensor nicht nur den Reflexionsgrad, sondern auch den Reflexionsabstand auswerten, um die Eisschichtstärken zu erfassen. Aus diesen Bedingungen heraus ist zu erkennen, daß der Reflexsensor ohne eine zusätzliche Information nicht immer das richtige Signal liefern kann. Mit Hilfe des Temperatursensors wird das Signal des Reflexsensors dem Zustand des Verdampfers eindeutig zugeordnet. So zum Beispiel bedeutet das Signal des Reflexsensors bei niedrigen Temperaturen das Vorhandensein einer Vereisung und bei positiven Temperaturen ein Vorhandensein von Wasser. Solange beim Abtauvorgang noch Eis vorhanden ist, beträgt die Temperatur höchstens 0 °C. Erst wenn der Temperatursensor positive Temperaturen erreicht, ist das Eis geschmolzen und kann dann der Abtauvorgang zur richtigen Zeit beendet werden. Die UND-Verknüpfung beider Signale ist ein wichtiges Merkmal des Signalgebers beziehungsweise Abtausensors. Mit dem Reflexsensor wird auch die Stärke der Eisschicht bestimmt. Vorteilhafterweise arbeitet der Reflexsensor im Infrarotbereich und wird er getaktet und wird vor dem Reflexsensor ein geeignetes Lichtfilter angeordnet, welches den Reflexsensor gegen Störlicht wie zum Beispiel Tageslicht oder Leuchtstofflampen, abschirmt und dadurch Fehlbeeinflussungen des Reflexsensors durch Störlicht ausschaltet.The type of icing of evaporators is strongly influenced by the state of the outside air. The ice layer on the evaporator can be found in a color range from transparent (ice partly with water) to white. The reflex sensor must recognize this area. Furthermore, the reflex sensor should not only evaluate the degree of reflection, but also the reflection distance in order to detect the ice layer thicknesses. From these conditions it can be seen that the reflex sensor cannot always provide the correct signal without additional information. With the help of the temperature sensor, the signal of the Reflex sensor clearly assigned to the state of the evaporator. For example, the signal from the reflex sensor means the presence of icing at low temperatures and the presence of water at positive temperatures. As long as ice remains during the defrosting process, the temperature is a maximum of 0 ° C. Only when the temperature sensor reaches positive temperatures, the ice has melted and the defrosting process can then be ended at the right time. The AND linkage of both signals is an important feature of the signal generator or defrost sensor. The thickness of the ice layer is also determined with the reflex sensor. The reflex sensor advantageously works in the infrared range and is clocked and a suitable light filter is arranged in front of the reflex sensor, which shields the reflex sensor against interfering light such as daylight or fluorescent lamps and thereby eliminates false influences of the reflex sensor by interfering light.

Claims (3)

1. A signal transmitter arrangement for controlling the defrosting of the air side of an evaporator means of a heat pump.or the like comprising a sensing assembly consisting of a temperature sensing device for measuring the temperature on the surface of said evaporator means and a sensing device responding to the formation of frost or ice, said two sensing devices being coupled to a receiver for the transmission of signals, wherein said signal transmittal arrangement comprises a thermally conductive console (1) attachable to said evaporator means to which said sensing assembly (2) is connected, said temperature sensing device (3) being connected with said sensing assembly in a thermally conductive fashion, and wherein said sensing assembly comprises a photosensitive sensing device (4) constituting the second sensing device the optic axis of said photosensitive sensing device being aligned to an auxiliary matte black reflective surface (12) arranged vertically on said console, said reflective surface having a circular area of reflection (14) convex relative to said sensing assembly (2).
2. A signal transmitter arrangement according to claim 1 wherein said auxiliary reflective surface (12) comprises a prong-shaped drip surface (13) the tip of said drip surface pointing downwards when said sensing assembly is fitted to said console.
3. A signal transmitter arrangement according to claim 1 or 2 wherein said console (1) is plate-shaped, the opposite edges (9) of said console approaching each other in a wedge-type fashion and wherein perforations (11) provided along at least one edge of said plate-shaped console allow a relatively easy reduction in the size of said console.
EP84100705A 1983-01-29 1984-01-24 Signal transmitter for controlling the defrosting process on the air side of the evaporator of a heat pump or the like Expired EP0117425B1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT84100705T ATE26170T1 (en) 1983-01-29 1984-01-24 SIGNALS FOR CONTROLLING THE DEFROSTING PROCESS ON THE AIR SIDE OF THE EVAPORATOR OF A HEAT PUMP OR SIMILAR.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE3303054 1983-01-29
DE3303054A DE3303054C2 (en) 1983-01-29 1983-01-29 Signal generator for controlling the defrosting of the evaporator of a heat pump

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EP0117425A1 EP0117425A1 (en) 1984-09-05
EP0117425B1 true EP0117425B1 (en) 1987-03-25

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EP (1) EP0117425B1 (en)
AT (1) ATE26170T1 (en)
DE (1) DE3303054C2 (en)
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ITRM20050634A1 (en) * 2005-12-19 2007-06-20 Ixfin S P A SYSTEM FOR THE AUTOMATED DEFROSTING OF A REFRIGERATOR SYSTEM.
ITPD20120148A1 (en) * 2012-05-10 2013-11-11 Enerblue S R L HEAT PUMP AND AUTOMATIC DEFROSTING METHOD OF CHECKING A HEAT PUMP
CN112303947A (en) * 2020-11-02 2021-02-02 中科美菱低温科技股份有限公司 Double-evaporator refrigeration system, refrigeration equipment and control method of refrigeration system of refrigeration equipment

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WO1983000211A1 (en) * 1981-06-26 1983-01-20 Alsenz, Richard, H. Refrigerator defrost control

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US3280577A (en) * 1963-11-20 1966-10-25 Matsushita Electric Ind Co Ltd Automatic defrosting control device
FI345773A (en) * 1973-11-08 1975-05-09 Upo Oy
DE2637129A1 (en) * 1976-08-18 1978-02-23 Bosch Gmbh Robert DEVICE FOR DEFROSTING EVAPORATORS IN REFRIGERANT CIRCUITS, IN PARTICULAR OF HEAT PUMPS
DE3001019A1 (en) * 1980-01-12 1981-07-23 Danfoss A/S, 6430 Nordborg DEFROSTING DEVICE FOR THE EVAPORATOR OF A REFRIGERATION SYSTEM
DD152404A1 (en) * 1980-07-28 1981-11-25 Dieter Voekler DEFROST CONTROL FOR THE INTRODUCTION OF DEFROSTING FOR COOLANT EVAPORATOR
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WO1983000211A1 (en) * 1981-06-26 1983-01-20 Alsenz, Richard, H. Refrigerator defrost control

Also Published As

Publication number Publication date
EP0117425A1 (en) 1984-09-05
DE3303054A1 (en) 1984-08-02
DE3303054C2 (en) 1994-02-10
NO158269B (en) 1988-05-02
ATE26170T1 (en) 1987-04-15
NO158269C (en) 1988-08-10
NO840332L (en) 1984-07-30

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