DE3340356A1 - Process for the operation of the prefreezing device of a freezing appliance equipped with an electronic control - Google Patents

Abstract

The process, especially for an upright or chest household freezer, is characterised by the following process steps, introduced on switching on the prefreezing device:   (a) Detection of the amount and kind of the new load (mNL) and switching of the refrigerating unit into permanent operation,   (b) Interrogation as to whether preconditions for the measurement and testing of given operating conditions are fulfilled,   (c) Determination of the temperature gradients with respect to time in the user space of the freezing appliance to determine the basic load (mGL) of the appliance,   (d) Determination of the ideal prefreezing temperature or determination of the permissible amount of the new load (mNL) for the prevailing basic load (mGL),   (e) Setting the calculated prefreezing temperature as the new controller reference value, and   (f) Switching off the prefreezing switch after the new controller reference value has been reached and indicating the readiness of the appliance for freezing. <IMAGE>

Description

BOSCH-SIEMENS HAUSGERÄTE GMBH 8000 Munich 80, October 13, 1983 7000 Stuttgart Hochstrasse 17

TZP 83Λ16 Wi / hü ·

Method for operating the pre -freezing device of a freezer equipped with an electronic control system

The invention relates to a method for operating the pre-freezing device a freezer equipped with an electronic control, in particular a domestic freezer or a household freezer.

Freezers of the type mentioned are usually with a Fast freezing circuit equipped, with the help of which the refrigeration unit of the device is switched to continuous operation and the The lower switch-off temperature of the controller is temporarily reduced considerably. When activated, this quick freeze circuit switches the refrigeration unit on regardless of the respective switching status of its temperature controller. As a result of this The setting of a sharp drop in temperature will be new The goods to be stored are quickly deprived of heat, which means that they are quickly frozen to the prescribed storage temperature. In this way you want to prevent some of the freshly stored, still warm goods in the "usable space of the freezer The amount of heat introduced is transferred to the frozen food that has already been stored for a long time and this exceeds the maximum permissible Temperature warmed. A further warming even for a short time could otherwise cause it to last longer In unfavorable circumstances, stored goods are sometimes even warmed to above freezing point and thus their quality and shelf life is significantly impaired.

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However, these known quick freeze switches cannot with certainty prevent larger quantities from being brought into the home Items to be newly frozen the temperature in the usable space of the freezer is temporarily above the maximum permissible temperature increases. In such cases, users of freezers are advised to freeze new ones for a long time Good thing to operate the quick freeze switch and thereby the Reduce the temperature in the usable space of the freezer well below the normal lower switch-off point of the regulator in order to In this way, thermal energy can be withdrawn from the stored base load, which is referred to in the following as "cooling capacity" To create a reserve that prevents the temperature from rising above the maximum permissible temperature in the freezer. The usual Rapid freeze switches thus have the function of a "pre-freeze switch".

The refrigeration capacity to be created in the manner described with the help of the pre-freezing switch depends to a large extent on the thermal capacity of the usable space of the device as well as on the amount of frozen food that has been stored for a long time and its nature - the so-called "base load" (m ",) - and depending on the lower switch-off temperature. If this base load is small, its cooling capacity is significantly lower when the lower switch-off point, which is set temporarily lower, is reached than is the case with a high base load. On the other hand, when the base load is high, the lower switch-off point is only reached after the refrigeration unit has been running for a considerably longer period of time, and in this case, under certain circumstances, a significantly higher refrigeration capacity is created than is the case for the respective quantity of goods to be newly frozen - the so-called "new load ¹¹ (m ™.)" If known pre-freezing switches are used with a small new load and a high base load, more energy than necessary is consumed, while with a low base load and a high new load, a corresponding cooling capacity can only be achieved by an uneconomical, very low lowering of the lower switch-off temperature.

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_ //. TZP 83/416

The invention is based on the object of specifying a method for pre-freezing in freezers of the type described in detail above, according to which the _{problems arising as a result of different base loads (nip, ·) and new loads (only T} ) are reliably eliminated in a simple manner.

This object is achieved according to the present invention in that when the pre-freezing device is switched on, the the following procedural steps are initiated:

a) Detecting the mass and type of the new load and switching of the refrigeration unit in continuous operation

b) Query whether preconditions for measuring and testing certain operating conditions are met *,

c) Determining the temperature gradient over time in the usable space of the freezer to determine the base load of the device,

d) Determining the ideal pre-freezing temperature or the permissible mass of the new load for the prevailing base load,

e) Set the calculated pre-freezing temperature as the new one Controller setpoint and

f) Switching off the pre-freezing switch after reaching the new controller setpoint and signaling that the device is ready to freeze.

With the sequence of the individual method steps according to the invention, the pre-freezing circuit is switched on for this ensured that regardless of the respective base load in the freezer, an optimal cooling capacity for the new to be frozen Well created.

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TZP 83/416

The method according to the invention is in the description below with the aid of a flowchart shown in simplified form in the accompanying drawing and three graphical ones Illustrations explained. Show it:

Fig. 1 is a flow chart showing the sequence of individual process steps after triggering the pre-freezing process emerges,

Fig. 2 is a graphical representation of the "when switching on the Pre-freeze switch occurring temperature decrease with different base load,

Fig. 3 and

FIG. H shows further graphic representations to explain individual method steps according to the flowchart.

In the diagram according to FIG. 2, the temperature o) L is plotted as the ordinate over the time t as the abscissa. Here, <\ 9) is the prescribed storage temperature of -18 ° C for long-term storage of frozen goods. This temperature corresponds to the upper switching point set on the controller of the freezer, and if this is exceeded, the refrigeration unit is switched on.

From this diagram it can be seen how the temperature in the interior of the device drops when the upper temperature is reached Switching point of the controller responds and the refrigeration unit switches on. The upper flat curve illustrates this Temperature profile in the case of a large base load, while the lower curve, which drops significantly more steeply, shows the temperature profile with a low base load. From this it can be seen that under the premise

* 2 " ¹ I ⁼ * 2

^ 4. τζρ 83Λ16

after the constant time interval represented by this has elapsed, in the case of a high base load the temperature * ^ L and in the case of a low base load the considerably lower temperature ^) is reached. The prevailing base load or the thermal capacity in the interior of the device can be determined on the basis of these relationships via the gradient of the interior temperature over time.

It is assumed that the pre-freezing cycle starts at a starting temperature A ^ triggered, the temperature gradient is then obtained with a constant time interval for the case of a small base load as

For the case of a different base load, the dependent, different temperature gradient results in an analogous way, In the following considerations, only the case is less Base load taken into account.

In the decomposed in the flowchart of FIG. 1 in the individual process steps procedure during pre-freezing process and during its release with "pre-freezing start" optionally simultaneous input of the mass m of the new _NL

First load the refrigeration unit in a temporary continuous run

·. in the flow chart

switched. Then according to (I) / it is checked whether corresponding preconditions are fulfilled, i.e. whether the device temperature is lower than the upper switching point of the controller, in this case -18 ° C. A precondition for this is that after the last closing of the door of the device, one of the device type The dependent minimum time has passed and the disruptive influences resulting from the last door opening have subsided.

If the above-mentioned preconditions are met, the temperature gradient becomes, as explained above, according to (2) for example with the help of a microprocessor

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averages. Here, however, it must be taken into account that this gradient of the puncture = F /. ν is not only _{dependent on the basic load ni GL} , but also on the absolute temperature inside the device, since the rate of fall also changes as the temperature drops.

These relationships, which emerge from the diagram according to FIG. 3, according to which the temperature mean (* ϋ ^ 2 ~ ^{Λ /} ±) ^{ί 2} changes, are caused by the deterioration in the efficiency of the refrigeration unit as the evaporator temperature drops and that with the decrease in the internal temperature increasing temperature difference to the outside temperature and the resulting increasing heat incidence through the thermal insulation of the device. For this reason, it is not yet possible to draw an exact conclusion about the base load m "from the size of the temperature gradient measured at any starting temperature below the upper switching point. If one does not want to be dependent on a fixed starting temperature, it must also be known at which temperature the gradient was measured.

According to (3), therefore, an arithmetic intermediate ^{value m} GL ^{must first be calculated from the} S ^e S enwär ' ^fci S ^en temperature gradient according to the time, whereby

is (evaluation of the gradient with the assumption ^ o ~ ^ ± ~ ^ o * ~ ^ '± * ⁼

c = constant).

In order to also take into account the absolute temperature in the measuring interval, according to (h) m _nr * must be multiplied by the factor nu, / m », - * from Fig. H in order to obtain the basic load of m« _T. From the base load m “obtained exactly from (k) in this way ^and the value of the new load m ™ to be inserted when the pre-freezing process was initiated, a function is then used with

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two variables, the ideal pre-freezing temperature for the special case λΛ calculated. This is then transferred to the ler program as the new setpoint.

temperature λΛ calculated. This is then sent to the temperature regulator

As soon as this temperature i / V is reached, the last Step of the procedure the readiness for the input Set amount of Neulast m ™ optically and / or acoustically signals. In the event that the amount entered at the beginning of the new load for the actually existing Grundalst and the cold capacity to be created by the pre-freezing process is too high, it can be provided that the highest, for In this case, the permissible new load is indicated by a visual display.

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Claims (1)

Claim Method for operating the pre-freezing device with one a freezer equipped with an electronic control system, in particular a household freezer or a household freezer, characterized by the following, Process steps initiated when switching on the pre-freezing device: a) Recording the mass and the type of new load (1%,) ^and switching the refrigeration unit to continuous operation, b) Query whether preconditions for measuring and testing certain operating conditions are met, c) Determination of the temperature gradient over time in the usable space of the freezer to determine the base load (fflp _T ) of the device, d) Determining the ideal pre-freezing temperature or determining the mass of the new load (nkr _T ) permissible for the prevailing base load (iHqt) » e) Set the calculated pre-freezing temperature as the new one Controller setpoint and f) Switching off the pre-freezing switch after reaching the new controller setpoint and signaling that the device is ready to freeze.