EP2126482B1 - Cooling furniture comprising two thermally separate compartments - Google Patents

Abstract

The refrigerating appliance has two blowers (21,21') separated thermally from each other. Each of the blowers is assigned to an evaporator (2,2') by which an expansion valve and the evaporator are switched one after the other in a refrigeration circuit (1) passing through the coolant. Two states are adjusted in an expansion valve with different non disappearing flow rate coefficient. An independent claim is also included for a method for operating the refrigerating appliance.

Description

The invention relates to a refrigerator with two thermally separated compartments, the evaporator are together with a compressor and a condenser in a refrigerant circuit and are acted upon by the compressor at a signaling of a refrigeration demand in the subjects with liquid refrigerant, wherein the amount of cold contributing cooling controlled is. Furthermore, the invention relates to a method suitable for operating this refrigerated appliance.

To control different subjects of a refrigerated cabinet to different temperature levels various designs of refrigeration units are known.

For example, in German Auslegeschrift DE 23 50 998 described a refrigeration cabinet with single circuit, which is designed inexpensively with only a single entry point for the refrigerant in the evaporator. Here, a freezer compartment and a normal refrigeration compartment each evaporator are assigned, which are connected in series in the refrigeration cycle. However, this series connection of the evaporator has the disadvantage that the dimensioning of the individual evaporator must be made according to the refrigeration demand existing in the individual subjects, or the temperature requirements given there. Consequently, the design of the evaporators can not be optimized with regard to a desired energy efficiency, since for this purpose the evaporators would have to be designed as large as possible. It is also of particular disadvantage that the temperature of the individual compartments can not be adjusted independently of each other, since in such refrigeration units with cooling required in a downstream in the refrigerant flow compartment also takes place in the upstream of this compartment subjects cooling.

In order to cool as possible independently of each other in refrigerated cabinets with multiple Kühlfächem, it is proposed to assign the individual Kühlfächem individually controlled bare cooling circuits. Such refrigeration furniture, for example, in the German patents DE 35 08 805 A1 or DE 40 20 537 A1 described. Here are the individual Kühlfächem associated evaporator in one Refrigerant circuit connected in parallel with each other. The entry points of the refrigerant in these evaporators have shut-off throttle valves. These throttle valves are individually controlled by a temperature control and thereby opened when a refrigeration demand is detected in the respective refrigeration compartment. In the in the DE 35 08 805 A1 described cooling furniture is provided in the refrigerant circuit in front of a branch leading to the evaporators, a reservoir for the intermediate storage of liquid refrigerant. From this it is possible to introduce additional refrigerant into the refrigerant circuit in a targeted manner by heating the reservoir in the event of an increased demand for refrigerant, in particular during simultaneous operation of both evaporators. In the in the DE 40 20 537 A1 described cooling furniture, the refrigerant to be introduced into the evaporator is withdrawn from the condenser according to its needs for one or simultaneously at several sampling points. A disadvantage of this prior art that, for the purpose of controlling the resulting from the connection or disconnection of the individual evaporator, variable amount of refrigerant energy-consuming storage means or inefficiently used condenser can be used. The parallel arrangement of several evaporators due to the dual design of the injection system (valve, throttle capillary, injection point) leads to significant additional costs compared to single circuits.

A single circuit, which is cost-effective and energy-efficient compared to the above systems and still makes the individual cooling compartments of the cabinet largely individually adjustable in their temperature, is in the German patent application DE 44 33 712 A1 described. Here are in the refrigeration cycle several evaporators in series, which are assigned along the flow direction of the refrigerant a freezer, a cold storage compartment and a Nonnalkühlfach. To individually cool the individual compartments of the refrigerator, the amount of cold introduced into the chain of evaporators is controlled specifically. Then, if only the first located behind the condenser evaporator of the freezer compartment to be cooled, the refrigerant circuit is withdrawn refrigerant and stored in a reservoir cached. This leads to a depletion of refrigerant in the evaporator chain, so that cooling no longer takes place in the downstream evaporator of the standard refrigeration compartment. But if now this normal refrigeration compartment be cooled, the coming of the condenser refrigerant flow is guided by deflection of the cooling circuit through the reservoir, so that in this way from this an increased amount of Refrigerant flows into the evaporator. By means of this controlled by a solenoid valve deflection mechanism in the refrigeration cycle, the amount of available refrigerant can be controlled with minimal energy consumption and at the same time the condenser even with low demand for refrigerant this unhindered produce for storage in the reservoir and caching. Again, the switched refrigerant line through the reservoir or past this leads to increased costs in the production of refrigerated cabinets.

The object of the invention is to find a cost-effective refrigerated cabinets with two thermally separated compartments and a suitable method for operating this cabinet in which a subject-specific temperature control using only a single common refrigeration cycle and given a uniform, modular production of evaporator components is possible.

The object is achieved by a refrigerated cabinet and a method suitable for operating this cabinet with the features of claims 1 and 8. Advantageous embodiments and further developments of the invention are described by the subclaims.

In the refrigerator with two thermally separated compartments each of these compartments is associated with an evaporator. Here, an expansion valve and these evaporators are connected in series in a refrigerant circuit. In an inventive manner, at least two states with different non-vanishing flow coefficients can be set on the expansion valve.

The invention is thus based on a targeted change in the flow coefficient of an expansion valve in the refrigerant circuit of a refrigerated cabinet. Hereby, the refrigerant flow through the evaporator of the refrigerator can be changed specifically. In a single circulation refrigerated cabinet, this causes a change in the ratio of liquid to gaseous refrigerant in the individual evaporators, and thus a change in the cooling capacity available in the evaporators.

From the variability of the cooling performance achieved in this way, the dimensions of the individual evaporators no longer exist, as was previously the case with refrigerated cabinets connected in series Evaporators usual, is determined by the expected ratio of the cooling capacities required in the individual subjects. The evaporators can therefore be sized large in terms of optimum energy efficiency.

Since the evaporator of the cabinet by the invention can be independent of the refrigeration demand in the individual compartments design / dimension, open up the potential profitable multi-zone refrigeration produce whose components (especially evaporator) uniformly (modular) can be used in large quantities and here the Advantages of known from the prior art refrigeration furniture in terms of energy efficiency and controllability of the subjects opened.

It is not necessary in the manufacture of the evaporator for the individual cooling compartments of the cabinet so that they can be manufactured as individual, individual components and to provide for mounting on the refrigerator. On the contrary, it is particularly advantageous to design the individual evaporators on a common carrier, thus creating a rapidly and cost-effectively installable evaporator module.

In order to enable a targeted control or regulation of the refrigerant flow through the evaporator, it is conceivable on the one hand to design the expansion valve such that its flow coefficient is infinitely adjustable. On the other hand, it is also very possible to carry out the expansion valve with switchable discrete flow coefficients. Such a discrete switchability is particularly useful in embodiments of refrigerated furniture, which have a few thermally separated compartments.

In order to regulate the temperature in the refrigeration furniture particularly advantageous, it is possible to assign the thermally separated compartments of the refrigerator temperature sensor. These temperature sensors are connected to an evaluation circuit for signaling a refrigeration demand in the individual compartments, this evaluation circuit forming part of a temperature control. If this Temperature control is signaled by one of the temperature sensor in at least one of the compartments of the refrigerator furniture a refrigeration demand, is set by the flow coefficient of the expansion valve so that the refrigerant flowing through it is preferably evaporated in the compartment in which the refrigeration demand was detected.

Fig. 1

ein Kühlmöbel mit einem Expansionsventil gemäß der vorliegenden Erfindung,

Fig. 2

mögliche Ausgestaltungen eines in dem Kühlmöbel einsetzbaren, dreistufig schaltbaren Expansionsventils.

Further advantages of the invention will become apparent from the following description of exemplary embodiments with reference to the accompanying figures. Show it:

Fig. 1

a refrigerator with an expansion valve according to the present invention,

Fig. 2

possible embodiments of an insertable in the refrigerator, three-stage switchable expansion valve.

In the Fig.1 According to the invention, a refrigerated cabinet with two compartments was used.

The Fig. 1 shows a refrigerated cabinet 20, which has two compartments 21, 21 ', which are to be regulated to different temperatures. Each of the compartments 21, 21 'is associated with an evaporator 2, 2'. These evaporators 2, 2 'lie in a refrigerant circuit 1 through which refrigerant flows in series behind a compressor 3, a condenser 4 and an expansion valve 5.

Each of the compartments 21, 21 'is associated with a temperature sensor 12, 12'. These temperature sensors 12, 12 'are connected to an evaluation circuit 11 for signaling a refrigeration demand, which forms part of a temperature control 10. In known manner, the temperature control 10 turns on a control line 14, the compressor 3 when in one of the subjects refrigeration demand is detected, and off again when no more refrigeration demand is detected. In addition, the temperature control 10 controls in the signaling of a refrigeration demand in at least one compartment 12, 12 'via a control line 13, the expansion valve 5 to set depending on the detected refrigeration demand whose flow coefficient.

As long as in any of the compartments 21, 21 'is a refrigeration demand and consequently the compressor 3 is turned off, the expansion valve 5 is kept closed by the temperature control 10. By thus preventing the pressure equalization between condenser 4 and evaporator 5 during the service life of the compressor 3 can be achieved depending on the design of the refrigerant circuit, an energy savings of about 3% -10%.

In order to be able to quickly introduce a larger amount of liquid refrigerant into the evaporators 2, 2 'in the event of a great need for refrigeration, it is advantageous to introduce into the refrigeration circuit 1 a reservoir 6 downstream of the condenser 4, which serves to receive liquid refrigerant. From this, if necessary, for example by heating the reservoir 6, additional short-term refrigerant can be introduced into the cooling circuit.

When refrigeration demand is detected in one of the compartments 21, 21 ', in a simple embodiment, the temperature control 10 at the expansion valve 5 will enter one of two discrete non-zero values of the flow coefficient, namely a low refrigeration requirement in the compartment 21' and a high value Refrigeration demand in compartment 21.

If the passage coefficient of the expansion valve 5 is set small by the temperature control 10, more refrigerant is extracted by the compressor 3 from the evaporators 2, 2 ', as is introduced via the expansion valve 5 in the evaporator 2, 2'. The pressure in the evaporators is low, the evaporation temperature accordingly low. In this way, the refrigerant evaporates only in the vicinity of its exit point from the expansion valve 5, in the evaporator 2 ', and essentially only the compartment 21' is cooled.

When the refrigeration demand is in the evaporator 2 farther from the expansion valve 5 along the flow path of the refrigerant, the passage coefficient of the expansion valve 5 is made large by the temperature control 10. Because of the Compressor 3 less refrigerant is sucked, as is introduced via the expansion valve 5 in the evaporator 2, 2 ', the pressure in the evaporator and, accordingly, the boiling point of the refrigerant increases. If it is higher than the temperature of the compartment 21 ', the refrigerant passes through the evaporator 2' without evaporating, and first evaporates in the evaporator 2 of the warmer compartment 21. In this way, substantially only the compartment 21 'is cooled.

A mean transmission coefficient can be selected if there is a simultaneous need for refrigeration in both compartments 21, 21 '. Then in each case a part of the refrigerant evaporates in the evaporator 21 'and the rest in the evaporator 21st

The same average transmission coefficient can be selected if the compartment 21 'has an unusually high refrigeration demand, for example during rapid freezing of newly stored refrigerated goods.

In order to set the required different values of the transmission coefficient, an expansion valve with continuously variable transmission coefficient can be used. Particularly simple and sufficient for most applications are expansion valves where only a small number of discrete values of the transmission coefficient are adjustable.

In the case of in Fig. 1 sketched cooling cabinet 20, which has two compartments to be cooled 21, 21 ', it is sufficient if two different non-vanishing transmission coefficients of the expansion valve 5 are adjustable. In this way, a very cost-effective temperature control can be realized profitably.

In the Fig. 2 Three possible embodiments of this suitable expansion valve 5 are shown. All embodiments are the same splitting (for example by means of T-piece) of the main line 31 of the refrigerant circuit at the entrance to the expansion valve 5 in two parallel conduit paths. After this splitting, these two conduction paths are fed to a blocking member 30. This locking member 30, z. B. a directional control valve, has a first switching stage, in which both conduction paths are shut off, a second switching stage, in which one of the two conduction paths open and the other is shut off, and a third switching stage, in which the other conduction path is open, wherein the a conduction path in this third switching stage may be open or disabled. At the exit of the locking member 30 is a capillary tube 34, which opens in a conventional manner directly into the evaporator 21 '.

When in the Fig. 2a ) outlined above exemplary embodiment of the expansion valve 5 include the above-mentioned parallel guided conduction paths upstream of the inputs of the locking member 30 capillary tubes 32, 33 of different length and the same cross-section. Depending on the switching stage of the blocking member 30, the refrigerant flows through the capillary tube 32, the capillary tube 33 or through both parallel, resulting in each case different flow coefficients of the expansion valve 5.

The same effect is when in the Fig. 2b ) sketched embodiment of the expansion valve 5 by using capillary tubes 42, 43 with different cross-sections.

In the in the Fig. 2c ) sketched expansion valve is provided on only one of the two line branches a capillary tube 52; the other line branch 53 has no significant flow resistance due to its short length or large cross-section. Turns the locking member 30 its passage on the line branch 53, this corresponds to a direct switching of the main line 31 to the capillary located at the output of the locking member 30 capillary 34. The line branch 53 thus forms a bypass around the capillary tube 52nd

Of course, the design of a multi-stage controllable expansion valve is not on in the Fig. 2 limited embodiments shown. Instead of Capillary tubes can be used in screens in an otherwise spacious refrigerant line. More than two non-zero values of the flow coefficient can be realized by providing a four-position directional control valve corresponding to the four possible combinations of "open" and "locked" of the two branches, or by making the main line 31 in the expansion valve 5 more than two parallel, individually switchable line branches is split.

Claims (11)

1. Cooling furniture (20) with two compartments (21,21') thermally separated from one another, wherein an evaporator (2, 2') is associated with each of the compartments (21, 21'), and with only a single common refrigerating circuit (1) flowed through by refrigerant, wherein the outlet of the first evaporator is directly connected with the inlet of the second evaporator, characterised in that an expansion valve (5) and these evaporators (2, 2') are connected in series in the refrigerating circuit and at least two states with different non-vanishing throughflow coefficients are settable at the expansion valve (5).
2. Cooling furniture according to claim 1, characterised in that the throughflow coefficient of the expansion valve (5) is steplessly settable.
3. Cooling furniture according to claim 1, characterised in that the expansion valve (5) can be switched over between discrete values of the throughflow coefficient.
4. Cooling furniture according to claim 3, characterised in that the expansion valve (5) comprises two parallel duct sections (32, 33, 42, 43, 52, 53) and a blocking element (30) for blocking one of the two duct sections in one of the two states.
5. Cooling furniture according to any one of the preceding claims, characterised in that a third state is additionally settable at the expansion valve (5), in which the valve is impassable by the refrigerant.
6. Cooling furniture according to any one of the preceding claims, characterised in that the evaporators (2, 2') are constructed on a common support.
7. Cooling furniture according to any one of the preceding claims, characterised in that arranged in the refrigerating circuit (1) downstream of the condenser (4) is a reservoir (6) serving for reception or intermediate storage of liquid refrigerant.
8. Cooling furniture according to any one of the preceding claims, characterised in that a respective temperature sensor (12, 12') is associated with each of the thermally mutually separate compartments, wherein these temperature sensors (12, 12') are connected with an evaluating circuit (11), which forms part of a temperature regulation (10), for signalling a requirement for refrigeration.
9. Method of operating an item of cooling furniture (20) according to any one of claims 1 to 8, in which a requirement for refrigeration in the compartments (21, 21') of the cooking furniture (20) is detected, characterised in that the control of the refrigerant supply is carried out by setting at least two states with different non-vanishing throughflow coefficients in a controllable expansion valve (5), wherein the state is selected in accordance with which of the compartments (21, 21') the requirement for refrigeration is detected.
10. Method according to claim 9, characterised in that on detection of a refrigeration requirement in the compartment of which the evaporator is remote from the expansion valve a higher throughflow coefficient expansion valve (5) is set and on detection of a refrigeration requirement in a compartment of which the evaporator is near the expansion valve (5) a lower throughflow coefficient of the expansion valve (5) is set.
11. Method according to claim 9 or 10, characterised in that if a requirement for refrigeration does not exist in either of the compartments (21, 21') of the cooling furniture (20) the expansion valve (5) is kept closed.

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