WO2013000759A2 - Refrigeration device with evaporation pan and auxiliary device for promoting evaporation - Google Patents

Abstract

A refrigeration device, especially a household refrigeration device, comprises at least one storage chamber (3) that can be closed by a door (2), an evaporation pan (9) for evaporating condensed water that is drained off from the storage chamber (3) and an auxiliary device (10, 12) which can be switched on additionally by a control unit (13) to increase the evaporation rate in the evaporation pan (9). The control unit (13) is designed to decide on whether the auxiliary device (10, 12) is switched on additionally based on the change of the temperature detected by the temperature sensor (14, 17) over time (S31-S33, S83-S84; S93-S96; S102-S107).

Description

 Refrigerating appliance with evaporation tray and auxiliary device for

 evaporation promotion

The present invention relates to a refrigeration appliance, in particular a household refrigeration appliance such as a refrigerator or freezer, with an evaporation tray for the evaporation of condensate discharged from a storage chamber of the device, and a

 Auxiliary device, which is switchable to promote the evaporation of the dew water in the evaporation tray, if necessary.

Each time you open a door of the refrigerator with the ambient air also

Moisture in the storage chamber of a refrigerator and is reflected there over time at the coldest point down, that is, depending on the design of the refrigerator, for example, directly to an evaporator or cooled by the evaporator wall of the storage chamber. From there, the moisture must be removed so that it does not affect the heat exchange between the storage chamber and the evaporator and thus the efficiency of the refrigerator and / or so that drained from this coldest point water does not wet the refrigerated goods. It is therefore usually below this coldest point a gutter or shell provided in which the condensation can collect and from where it through a passage in the

heat-insulating wall of the refrigerator is passed to an evaporation tray. The evaporation tray is located beyond the heat-insulating wall to release moisture evaporating from it freely to the environment. To the

To promote evaporation in the shell, it is traditionally in one

Engine room of the refrigerator mounted on a compressor to pass through

Waste heat to be heated.

Improvements in insulation and cooling in modern refrigeration appliances mean that the ratio of accumulating condensate to the waste heat available at the compressor is becoming increasingly unfavorable. However, if the condensation is faster than it can evaporate in the evaporation tray, it overflows, and the leaking water can damage the unit and its surroundings. One way to replace the lack of waste heat from the compressor is to attach an electrical heater to the evaporation tray. However, it is obvious that the operation of such a heater, especially if he does not

controlled in a demand-oriented manner, which impairs the overall energy efficiency of the refrigeration device and improves efficiency through improved insulation or improved

Largely destroys refrigeration. Although it would be conceivable to attach a level sensor to the evaporation tray and to operate the heater only if it indicates the exceeding of a critical water level. However, such a level sensor must have a high degree of reliability, because if a fault of the level sensor is that an exceeding of the critical water level is not detected, overflowing the evaporation tray threatens with the resulting consequential damage. If, on the other hand, a malfunction of the level sensor leads to the fact that an exceeding of the critical water level is constantly detected, then the heating device runs non-stop, and energy is wasted uselessly. Since such a disturbance does not immediately manifest itself externally, it may be overlooked for a long time and cause considerable costs for the user. However, a level sensor with the reliability required for practice leads to not negligible and often dissuasive for the user costs in the device manufacturing. Object of the present invention is therefore to provide an inexpensive and reliable solution with which sufficient evaporation of condensation can be ensured and at the same time a good energy efficiency of the refrigerator is maintained.

Under a refrigeration device is in particular a household refrigeration appliance understood, ie a refrigeration appliance for household management in households or possibly in the

 Catering area is used, and in particular serves to store food and / or drinks in household quantities at certain temperatures, such as a refrigerator, a freezer, a fridge-freezer, a freezer or a wine storage cabinet.

The problem is solved by a refrigeration device, in particular a

Domestic refrigeration appliance, with at least one storage chamber, arranged in thermal contact with the storage chamber temperature sensor, an evaporation tray for Evaporation of discharged from the storage chamber condensation and a

Auxiliary device, which can be switched by a control unit to increase the evaporation rate in the evaporation tray, the control unit is set up, a decision on the connection of the auxiliary device (10, 12) based on the time course of the temperature sensor (14, 17) detected temperature hold true.

As an intermediate in the decision making, the control unit

expediently calculate a count quantity correlated with the amount of water in the evaporation tray. The decision that the connection of the auxiliary device is necessary can be made if the count size exceeds a limit value.

The temperature detected by the sensor is linked by various relationships with the accumulating amount of condensate. For example, each opening of a door of the storage chamber leads to an inflow of warm, moist ambient air in the

Bearing chamber. Therefore, a jump in the detected temperature caused by this inflow can be used by the control unit to detect that moisture has entered the storage chamber and will soon reach the evaporation tray as well.

Another related fact is that the cooling of an evaporator located at the storage chamber is delayed when moisture from the air flows through the air

Storage chamber condensed thereon. If the cooling rate is known, which is known to the evaporator with known moisture content of the air of the storage chamber, especially if it is dry and no condensation takes place, then by a deviation between this and a measured

Cooling Rate the extent of condensation can be estimated. For such an estimate, a short observation period is sufficient; in particular, in the case of a refrigeration device with an intermittently operated compressor, a judgment of the

Condensation rate already possible after an observation period, which is significantly shorter than an operating phase of the compressor. In order to measure the effect of the condensation on the evaporator temperature exactly, it is expedient if the temperature sensor is mounted on the evaporator. The count size may optionally be incremented in proportion to the calculated deviation by the amount accumulated in a given period of time or, in the case of an intermittently operated compressor, during an operating phase of the compressor

To reflect condensation. A delay in cooling by condensation may also be exploited by integrating, when an expected temperature is known as a function of time, the difference between a temperature measured by the temperature sensor and the expected temperature over time. Also this integral is proportional to the accumulating

Condensate volume.

Also, the integral thus obtained or a variable proportional to it may serve as the above-mentioned count quantity.

It is also expedient, if the control unit is set up, to take into account the temperature of the storage chamber and / or the ambient temperature when determining the connection, since the ambient temperature determines how much moisture may be present in a given amount of ambient air contained in the storage chamber, and the temperature of the storage chamber (in which both an actual temperature, for example the temperature detected by the temperature sensor and a setpoint temperature set by a user can be taken as a basis), allows conclusions to be drawn as to what percentage of the ingress of moisture will actually condense out.

This consideration of the temperature can be done easily by the control unit weighting the increment with a temperature dependent on the temperature of the storage chamber and / or the ambient temperature factor.

In order to take the ambient temperature into account, the control unit may be connected to an ambient temperature sensor. With comparable reliability cheaper techniques are feasible

Estimation of the ambient temperature on the basis of related variables. Thus, for example, if the refrigeration device comprises a compressor which is operated intermittently in a manner known per se, the control unit can be set up Estimate ambient temperature based on the duration of an operating phase of the compressor. The duration of an operating phase depends not only on the difference between the switch-on and switch-off temperature of the compressor, but also on the rate at which ambient heat penetrates into the storage chamber and delays its cooling during operation of the compressor. The higher the ambient temperature, the higher the rate, and accordingly, each operating phase lasts longer.

Refrigeration appliances are also known, in which the capacity of the compressor is variable and regulated to a value at which the compressor can run continuously or almost continuously while keeping the temperature of the storage chamber constant. The capacity of the compressor to equalize the flow of heat from the storage compartment environment depends on the ambient temperature, specifically the difference between the ambient temperature and the temperature of the storage chamber, so that the performance to which the compressor is subjected at one such refrigeration device is regulated, also allows a conclusion on the ambient temperature.

If the average operating temperature of the evaporator is so low that

Humidity precipitated as frost, which does not defrost between two phases of operation of the evaporator, then defrosting can be provided for defrosting the evaporator. Liquid condensate then essentially only accumulates when the defrost heater is in operation. Therefore, the control unit is in such a case

Preferably arranged to operate the auxiliary device together with the defrost heater to eliminate this condensation quickly.

As an auxiliary device, in particular a heater and / or a fan come into consideration.

Further features and advantages of the invention will become apparent from the following description of embodiments with reference to the accompanying figures. From this description and the figures are also features of the

Embodiments, which are not mentioned in the claims. Such features may also occur in combinations other than those specifically disclosed herein. The fact that several such features are mentioned in the same sentence or in a different type of textual context therefore does not justify that Conclusion that they can occur only in the specifically disclosed combination;

instead, it must be assumed that, of several such characteristics, it is also possible to omit or modify individual ones, provided that this is the case

Functionality of the invention is not in question. Show it:

Figure 1 is a schematic section in the width direction by a household refrigerator according to the present invention.

2 shows a section in the depth direction through the refrigeration device.

Fig. 3 is a flowchart of a method for controlling the evaporation

 supporting auxiliary device;

4 shows an exemplary temperature profile in the storage chamber of the refrigerator of FIGS. 1 and 2;

FIG. 5 is a flowchart of a method of controlling the auxiliary device based on the temperature history shown in FIG. 4; FIG.

6 is a flowchart of a second on the temperature profile of FIG .. 4

 based method;

7 shows exemplary temperature profiles on the evaporator of the refrigerator of FIGS. 1 and 2; and

FIG. 8 is a flow chart of a method of controlling the auxiliary device based on the temperature characteristics shown in FIG. 7; FIG.

FIG. 9 is a flowchart of a second method based on the temperature characteristics of FIG. 7; FIG. and

10 is a flowchart of another, on temperature measurement in the

Bearing chamber based method. Figs. 1 and 2 show schematic sections through a household refrigerator, to which the present invention is applicable. The sectional planes of the two figures are shown in the other Fig. As dash-dotted lines ll or II-II.

The household refrigerator, here a refrigerator, has in the usual way

heat-insulating housing having a body 1 and a door 2 defining a storage chamber 3. The storage chamber 3 is here cooled by a coldwall evaporator 4 arranged on its rear wall between an inner container of the body 1 and an insulating foam layer surrounding it, but it should be immediately obvious to the person skilled in the art that the features of the invention explained below also apply in connection with FIG any other types of evaporator are applicable.

The evaporator 4 is part of a refrigerator which further comprises a compressor 6 housed in a machine room 5 recessed from the cabinet 1 and a condenser not shown in the figures, which may for example be accommodated on the outside of the rear wall of the cabinet 1 or in the machine room 5 ,

At the foot of the cooled by the evaporator 4 rear wall of the storage chamber 3, a collecting channel 7 extends for condensed water, which is reflected at the area cooled by the evaporator 4 of the inner container and flows down there. A pipeline 8 leads from the lowest point of the gutter 7 through the insulating

 Foam layer through to an evaporation tray 9, which is mounted on a housing of the compressor 6, to be heated by waste heat of the compressor 6. An electric heater 10 is here in the form of a inside of the

Evaporation tray 9 extending heating loop shown; It could also, for example, in the form of a film heater on an outer wall 1 1 of

Evaporation tray 9 may be mounted, in which case outside the film heater around still an insulating layer may be provided to ensure that the heater emits its heat substantially in the evaporation tray 9 inside. In order to promote the evaporation of condensate in the evaporation tray 9, instead of the heater 10 or in addition to this still a fan 12 may be arranged in the engine room 5 so that it drives an air flow over the water level of the evaporation tray 9. Since the on and off times of the Heater 10 and the fan 12 are linked and preferably the same, the description may be limited to the case that both are present.

Heating device 10 and fan 12 are controlled by an electronic

Control unit 13, which is shown here for simplicity in the engine room 5, but in practice largely arbitrarily on the refrigerator and in particular adjacent to a - not shown - control panel can be arranged. The control unit 13 also controls the operation of the compressor 6 on the basis of a temperature sensor 14 arranged on the bearing chamber 3. As will be explained in more detail below, a simple on-off control of the compressor 6 can be provided within the scope of the invention, in which the control unit 13 turns on the compressor 6, when the temperature of the storage chamber, a switch-on threshold T _a exceeds 3, and it turns off again as soon as the temperature of the storage chamber 3 is below a switch-off threshold T _off. However, it is also a continuous control of the power, in particular the speed of the compressor 6 or switching between numerous discrete non-vanishing power levels of the compressor 6 in dependence on the measured temperature into consideration.

On a side wall of the body 1 an operable by the door 2 switch 15 is mounted, which can serve in a conventional manner for switching on and off a lamp 16 of the storage chamber 3 when opening or closing the door 2. The switch 15 may be connected to the control unit 13 in order to allow detection of the opening and closing of the door 2 by the control unit 13 in the context of a control method which will be described below.

For some of the control methods described below, a second temperature sensor 17 may be arranged directly on the evaporator 4 in order to control its temperature

To detect temperature and report to the control unit 13. 3 is a schematic flow diagram of a method executable in the control unit 13 according to a first embodiment of the invention to control the operation of the heater 10 and the fan 12. In step S31, the

Control unit 13 from that opening of the door 2 is detected. This detection can by means of of the switch 15 or by one of the methods described later with reference to FIGS. 4 to 6.

If a door opening has been detected, an internal counter c of FIG

Control unit 13 by an increment incr (T _ext , ...) increases, the value of which is proportional to an estimated amount of passing through the door opening in the storage chamber 3

Moisture level is set. This amount can be estimated on the basis of parameters such as the temperature T _ext in the vicinity of the refrigerator or the duration of the door 2 open. It is easy to understand that the amount of ambient air that enters the storage chamber 3 when opening the door 2, the greater, the longer the door 2 is open, and that, accordingly, the amount of water introduced with the ambient air increases. However, as soon as the air in the storage chamber 3 is completely replaced, the registered amount of moisture increases only slowly. Therefore, it can be assumed in a simple embodiment of the method that with each door opening the air is completely replaced; then only the number of door openings, but not their duration in the increment needs to be considered. A more accurate estimate of the moisture input is achieved if a correspondingly reduced increment is taken as the basis for a short door open which is insufficient for complete air exchange.

In order to be able to estimate the ambient temperature T _ext , a

Ambient temperature sensor may be provided on the refrigeration device outside the insulating layer; an alternative, less expensive feasible option, if the compressor 6 is operated intermittently, to measure the duration of an operating phase of the compressor 6 and the ambient temperature based on a previously determined empirically

_Estimate relationship between the ambient temperature T _ext and the actual detected by the temperature sensor 14 temperature T or set by the user set temperature of the storage chamber 3 and the duration of the operating phase.

When the compressor 6 operates continuously and from the control unit to a

Level of performance is regulated, in which a constant temperature T of the

Storage chamber 3 results, then the ambient temperature T _ext in an analogous manner estimated from a known relationship between temperature T, compressor power and ambient temperature.

A disadvantage of these approaches based on the control of the compressor 6, however, is that changes in the ambient temperature can be correctly taken into account only with great delay, when the control of the compressor has adapted to it. Procedures that allow faster consideration of a changed

Ambient temperature will be described later with reference to FIGS. 7 to 9.

In step S33, it is checked whether the counter has exceeded a limit value c _ma x which corresponds to a critical water level in the evaporation tray 9. If so, in step S34, the heater 10 and / or the fan 12

turned on, the counter c is reset in step S35, and the process returns to the output. While heater 10 and fan 12 are in operation, the detection of door openings continues with steps S31, S32, S33 and the concomitant re-increment of counter c. In each case, after a predetermined operating time, which is determined empirically as sufficient to evaporate an amount of water corresponding to the limit c _ma x and so to reduce the water level in the evaporation tray 9 back to a safe level, heating device 10 and fan 12 are turned off again.

To the contribution of the waste heat of the compressor 6 to the evaporation in the shell. 9

In the case of on-off control of the compressor 6 by the control unit 13, it may be provided that, when the compressor 6 is in operation, the count value c is reduced by a predetermined decrement at regular time intervals. In the case that the compressor 6 is operated continuously at variable power, the amount of decrement can be set proportional or the time interval between two decrements inversely proportional to the compressor power.

Fig. 4 shows typical courses of the temperature sensor 14 over time

measured temperatures, each as a solid line in the absence of

Door openings and dashed in the case of a door opening. Each to having _a t

designated time reaches the temperature T in the storage chamber 3 a

Switch-T _a, which causes the control unit 13, the compressor 6 turn on; at the designated time points with t _from the temperature T reaches a switch-off threshold _of T, in which the control unit 13 turns off the compressor 6. As long as the door remains closed, the time between these times changes

Temperature T continuous. If, during the operation of the compressor 6, the door is opened, such as at times t1, t2, t4, then this results in a

Temperature increase, but if after a short time the heat of the penetrated air has been distributed in the storage chamber 3, the detected by the sensor 14 differs

Temperature T is no longer significantly different from the temperature, which is without a

Door opening would have resulted. When the compressor 6 between times _t, and t _a is turned off, the temperature T is continuously increasing, especially when passing through a door opening of warm air into the storage chamber. 3 A drop in temperature that occurs when the compressor is switched off when the heat introduced in the storage chamber 3, however, allows a clear conclusion that a door opening has taken place.

FIG. 5 shows a flowchart of a first method which employs the monitoring of the temperature T in the storage chamber 3 to carry out the step S31. The process is repeated at regular intervals, regardless of whether the compressor 6 is turned on or not. In step S51, the temperature T, which

Storage chamber 3 detected at the time of the ith iteration of the process. If the compressor is turned on at this time, the process branches in step S52 to step S53, where it is checked whether the measured value T, is higher than the measured value Τ, .- ι obtained in the previous iteration. If not, the iteration is finished. Otherwise, the method reaches step S55.

If it is determined in S52 that the compressor is off, it is checked in S54 whether the temperature T, is lower than the temperature Tu measured in the previous iteration. If not, the iteration is finished again, if yes, step S55 is reached. In S55 it is concluded that the door has been opened.

To ensure that a door opening is not counted several times, in step S56 wait until either the compressor 6 changes its operating state or, if at the time of detection of the door opening the compressor 6 was turned on, the Temperature T begins to fall again or, if the compressor 6 was off, the temperature T starts to rise again.

A higher detection sensitivity is achievable with the method of FIG. 6.

A prerequisite for this method is that the control unit 13 normal values for the time derivative of the temperature T with switched on and off compressor 6 are known. These values can be programmed by the manufacturer, or they can be based on measurements of the temperature profile that the control unit 13 itself performs on the refrigeration device. Again, in step S61, first the current temperature T, at the time of the ith

Iteration measured. The time derivative dT, / dT is calculated in step S62 on the basis of a temperature value Tu measured in the respectively preceding iteration. Step S63 checks whether the derivative thus calculated is more positive than normal, i. as the rate of change of temperature that would be expected with the door closed, taking into account the compressor operating condition. If this is not the case, then the iteration ends; if it is the case, it is concluded in S64 that the door has been opened. Again, to avoid multiple counts, in S65 the temperature T is still measured at regular intervals and its derivative calculated, but for

The starting point of the process is only returned when the thus obtained

Derivative values are normalized again, i. the disturbance caused by the door opening has subsided in the normal course of temperature.

A method for controlling the operation of heater 10 and fan 12, which is not based on an estimate of the ambient temperature is explained with reference to Figures 7 and 8. The diagram of FIG. 7 shows two curves of the temperature Tv of the evaporator 4 as a function of the time t, it being assumed in each case that the control unit 13 switches on the compressor 6 at a time tO. Before the switch-on time tO, with the compressor 6 switched off, the temperature Tv of the evaporator 4 rises very slowly together with the temperature T of the storage chamber 3. A short time after switching on the compressor 6, the temperature Tv starts to fall. The speed of the temperature drop depends on the humidity in the storage chamber 3 and the rate at which this humidity on the evaporator 4 is reflected as condensation. The fastest drop, shown as curve A in Fig. 7, is given when the air in the storage chamber 3 is dry and no condensation heat through

Condensation water is released at the evaporator 4. However, when condensation is precipitated, it delays the cooling of the evaporator 4 and results in a curve such as curve B. The method illustrated in the flow chart of FIG. 8 utilizes this variable one

Cooling behavior of the evaporator 4 to control the heater 10 and the fan 12: in step S81, the control unit 13 waits until the temperature T of the

Storage chamber 3 has risen above the switch-on threshold T _a . Once this is the case, in step S82, the compressor 6 is turned on, and a timer is set in motion to measure the elapsed time t from the switch-on time tO.

In step S83, the actual temperature Tv at the evaporator at the current time t is measured by means of the temperature sensor 17 and compared with a value Tv _ref (t), which would be expected according to curve A at this time t, when the air in the

Storage chamber 3 would be completely dry. The difference between the two temperatures Tv (t) and Tv _ref (t) is a measure of the rate at which condensation on the evaporator 4

reflected. A count c is incremented by this difference. In step S84, the count value c is compared with a threshold value c _ma x, and as described with reference to Fig. 3, when the threshold value c _max heater 10 and fan 12 are exceeded (S85), the count value c is reset (S86). The steps S83, S84 are repeated so long until it is determined in step S87 that the storage chamber to the switch-off temperature T _out is cooled. Once this is the case, the process returns to the origin S81. The repeated summation in step S83 corresponds to a numerical integration of the difference between the two curves B, A of FIG. 7. The value of the integral, c, can be assumed to be proportional to the accumulated amount of condensation water. The period of time during which the heater 10 and fan 12 remain on after step S85 is empirically determined to be sufficient to correspond to the c _ma x

Amount of condensation water to evaporate. This period obviously depends on the power of the heater 10 and the fan 12, but also on the waste heat capacity of the compressor 6 in operation. 9 shows a flow chart of a second on the evaluation of

Condensation heat based method. The steps of waiting for reaching the switch-T _{is a} S91 and the starting of the compressor S92 and starting the timer correspond to steps S81, S82. When the compressor has run for a first predetermined time t1, a first measurement of the

Evaporator temperature Tv (t1) instead (S93). A second measurement (S94) takes place at time t2. On the basis of these two measured values, a typical rate of decrease of the curve B can be determined. In step S95, the difference between this decrease rate and a decrease rate Tv _ref (t2) -Tv _ref (t1) of the curve A stored beforehand empirically and stored in the control unit is calculated at these two points in time. This difference is again representative of the condensation rate at the evaporator 4 and thus for the total amount of moisture contained in the air of the storage chamber 3 and will be reflected in the course of the current operating phase of the compressor 6 at the evaporator 4. Accordingly, the count c is incremented by this difference in S95. The value of c is thus representative of the amount of condensation water at the end of the

Operating phase of the compressor 6 of the evaporation tray 9 would be included, unless the evaporation is promoted by operation of the heater 10 and the fan 12.

In step S96, it is checked whether the count value c has exceeded the threshold c _max . If not, in the current operating phase of the compressor, the fan 12 and the heater 10 are not needed, and the process returns to step S91 to await the next compressor operation phase. If c _{max is} exceeded, heater 10 and fan 12 are turned on (S97) and remain in operation as long as necessary to evaporate the amount of water corresponding to c _ma x.

Accordingly, the count value is decremented by c _ma x in step S98 before the process returns to step S91.

A further embodiment of a method for controlling heating device 10 and fan 12 is shown in FIG. 10 on the basis of the temperature T detected by temperature sensor 14 of storage chamber 3. Again, in step S101, first, the current temperature T, the storage chamber 3 is measured. In step S102, it is checked whether this temperature is higher than the normal temperature corresponding to the solid curve in FIG. 4. If not, the iteration ends, otherwise, in step S103 the extent of deviation d, between actual temperature T, and

Normal temperature calculated. Step S104 compares this deviation d, with a value d _ma x stored from a previous iteration. If the deviation d, is greater, d _ma x is overwritten with d, in S105, and the iteration ends. In the opposite case, the maximum of the deviation from the normal temperature occurring after a door opening is exceeded, and the stored value d _max denotes the maximum of this temperature deviation. This maximum may be understood as a measure of the amount of ambient air entering the storage chamber 3 at the door opening, and the amount of moisture contained in this ambient air is estimated by measuring dmax in step S106 with a function of, for example, a suitably arranged sensor Ambient temperature T _{ext is} multiplied. In order to estimate the ambient temperature T _ex t without using a separate sensor, the control unit may, for example, a known relationship between ambient temperature, target temperature of the storage chamber 3 and - with intermittently operating compressor 6 - the duration (t _from -t _e in) an operating phase of the compressor , or the average power of the compressor 6 draw. A count c representative of the water level in the evaporation tray is incremented around the product thus obtained, and d _ma x is reset to zero to prepare for detection of a later door opening.

The subsequent steps S107 of the comparison with the limit value c _max , possibly the switching on S108 of heater 10 and fan and the resetting S109 of the count value c correspond exactly to the steps S33 to S35 of the method of Fig. 3. This method allows door openings of the same Duration, which lead to different lengths of deviations from the normal temperature, because in one case (eg t1 of Fig. 4) chilled removed, in the other case (eg t2 of Fig. 4) warmed refrigerated goods was invited to treat the same, long Continuous door openings, the penetration of a large amount of ambient air and a

correspondingly high temperature deviation (such as t4 of Fig. 4), but to weight higher.

Claims

Refrigerating appliance with at least one storage chamber (3), a temperature sensor (14, 17) arranged in thermal contact with the storage chamber (3), an evaporation tray (9) for evaporating condensate discharged from the storage chamber (3) and an auxiliary device (10, 12 ), which is switchable by a control unit (13) to the evaporation rate in the Evaporation tray (9) to increase, characterized in that the Control unit (13) is arranged, a decision on the connection of the auxiliary device (10, 12) based on the time course of the Temperature sensor (14, 17) detected temperature (S31-S33, S83-S84; S93-S96; S102-S107). Refrigeration appliance according to claim 1, characterized in that the control unit (13) is arranged to calculate a count quantity (c) correlated with the amount of water in the evaporation tray (9) (S32; S83; S95; S106) and to decide (S33; S84 S96, S107) that the connection of the auxiliary device (10, 12) is necessary when the count size (c) exceeds a limit value (c _ma x). Refrigeration appliance according to claim 2, characterized in that the control unit (13) is set up, the count size (c) upon detection (S51-S54; S61-S63) of a jump caused by opening a door (2) of the storage chamber (3) to increase the temperature detected by the temperature sensor (14) (S32). Refrigeration appliance according to claim 1, characterized in that the control unit (13) is set up the time profile of the temperature detected by the temperature sensor (14, 17) by calculating (S62; S95) a deviation of the time derivative (dT dt; Tv (t2 ) -Tv (t1)) of the temperature from a reference value (Tv _ref (t2) -Tv _ref (t1)). Refrigerating appliance according to claim 4, as far as dependent on claim 2, characterized in that the control unit (13) is arranged to increment the count size (c) in proportion to the calculated deviation (S95). Refrigeration appliance according to claim 1, characterized in that the control unit (13) is adapted to the time course of the temperature sensor (17) detected temperature by integrating (S83) the difference between one of the temperature sensor (17) measured and an expected temperature consider. Refrigerating appliance according to claim 6, characterized in that the temperature sensor (17) is attached to an evaporator (4). Refrigerating appliance according to claim 6 or 7, as far as dependent on claim 2, characterized in that the control unit (13) is adapted to use a proportional to the integral of the difference size as the count size (c). Refrigerating appliance according to one of the preceding claims, characterized in that the control unit (13) is set up, in the decision (S33, S107) via the connection, the temperature of the storage chamber (3) and / or  Ambient temperature to be considered (S32, S106). Refrigerating appliance according to claim 9, as far as dependent on claim 3 or 5, characterized in that the control unit (13) is arranged, the increment with one of the temperature of the storage chamber (3) and / or the  Ambient temperature dependent factor (S32, S106). Refrigerating appliance according to one of claims 9 to 1 1, characterized by an ambient temperature sensor connected to the control unit. Refrigerating appliance according to one of claims 9 to 1 1, characterized in that it comprises an intermittently operated compressor (6) and that the Control unit (13) is _{adapted to} estimate the ambient temperature (T _ext ) on the basis of the duration (t) of an operating phase of the compressor (6). 13. Refrigerating appliance according to one of claims 9 to 1 1, characterized in that it comprises a compressor (6) for holding the storage chamber (3) on a Target temperature variable power is operable, and that the control unit (13) is arranged, the ambient temperature based on the performance of the  Estimate compressor (6). 14. Refrigerating appliance according to one of the preceding claims, characterized in that it comprises a humidity sensor for detecting the humidity in the  Storage chamber and the control unit is adapted to take into account the measured humidity in controlling the operation of the auxiliary device. 15. Refrigerating appliance according to one of the preceding claims, characterized in that it has a defrost heater and that the control unit is arranged to operate the auxiliary device together with the defrost heater. 16. Refrigerating appliance according to one of the preceding claims, characterized in that the auxiliary device comprises a heater (10) and / or a fan (12).