GB2040427A - Single-compressor refrigerator and freezer - Google Patents

Abstract

A combination refrigerator and freezer, 10, in which a single compressor, 11, services the evaporators, 15 and 16, of the refrigerator and the freezer sections respectively. The evaporators are arranged in a cascade set up. A solenoid valve, 14, shifts the fluid from the compressor to the freezer evaporator only, or to both evaporators, as commanded by their respective thermostats. <IMAGE>

Description

SPECIFICATION Single-compressor refrigerator and freezer This invention relates to improvements in or relating to the refrigeration circuits for combination refrigerator-freezer machines.

The combination refrigerator-freezers are usually equipped with two compartments, viz.: one compartment, the refrigerator proper, in which a temperature is maintained, internally of the cupboard, which is a few degrees above zero Celsius for preserving, for example, foodstuffs intended for shortterm consumption, and a compartment, the freezer, which has an internal temperature in the order of several degrees below zero and is thus adapted for the long-term storage of foodstuffs.

Considering now the different thermal conditions of the two compartments, which must be maintained within a narrow range astride the preselected temperatures, it becomes often necessary to equipe each individual compartment with a discrete refrigerating circuit, with a compressor of its own and attendant throttling and expansion valve and like members. In this case, the problem is solved by having each refrigerating circuit working independently of the other one responsively to a thermostatic device arranged in the relevant compartment.

Whenever, conversely, it is desired to exploit a single refrigeration circuit for cooling both compartments, the problem is to make possible the necessary withdrawal of calories from both cells, even though it is quite obvious that the relevant demands are extremely variable in time inasmuch as a condition of stable thermal equilibrium cannot be established. In this connection, it is sufficient to have in mind the unbalances as caused by merely opening the door, the introduction in a compartment of materials having a comparatively high temperature and which must be refrigerated and so forth.

An objective of this invention is to provide an improved refrigeration circuit which, by exploiting a single unit for compression, throttling and condensation, enables calories to be withdrawn from two compartments having two different temperatures, such a circuit being capable, in a specially advantageous manner, of coping with the demands, which are variable, of calorie withdrawal as required for maintaining the preselected temperatures in each compartment.

This objective is achieved according to the basic principles of this invention buy a refrigeration circuit in which a compressor sends the frigorific fluid, as compressed, to evaporators via a condenser, characterized in that said evaporators are two, the first for a refrigeration compartment, and the second for a freezer compartment, the former discharging fluid into the input to the latter, valve means connecting in alternate sequence the first or the second evaporator to the delivery side of the compressor, said valve means being driven by devices which are responsive to the temperatures of the respective compartments.

The features and advantages of the machine constructed according to this invention will become clearer anymore easily understandable by scrutinizing the description of an exemplary embodiment thereof as illustrated in the accompanying drawings, wherein: FIGURE 1 is a diagrammatical view of a combination refrigerator and freezer.

FIGURES 2 and 3 are views, fragmentary and in cross-section, of a solenoid valve having two ways and three outputs, which are a component part of the machine in question as shown in FIGURE 1, the Figures showing two different working positions of the valve.

FIGURE 4 is a simplified wiring diagram showing the electric connection provided between the components of the machine of FIGURE 1.

By way of illustrative example only, a combination refrigerator and freezer 10 is composed by a compressor 11, a condenser 12, a dehydration unit 13, a two-way, three-output solenoid valve 14, an evaporator 15, for example, of the plate type, housed in the refrigerator compartment and a similar evaporator 16 intended to be housed in the freezer compartment, said means being mutually connected by pipes in which a refrigerating fluid flows.

As regards the circuital connections of the principal component parts indicated above, it is observed that the delivery side of the compressor 11 is connected via a tube 20 to the condenser 12 wherein the fluid is condensed and yields heat to the external environment.

From the condenser 12 the fluid (refrigerating fluid) reaches a capillary tube 22 in which a dehydrator 13 is serially connected, the tube being extended by a piping 26 opening into a valve 14. The valve 14, moreover, is also connected to a piping 25 which feeds the evaporator 15, and to a piping 24 which opens into a fitting 28.

The fitting 28 is connected also to the discharge conduit 21 of the evaporator 15 and the conduit 29 of input to the evaporator 16, which latter discharges via the duct 27 into the intake side of the compressor 11.

The electromagnetic valve 14 is best seen in FIG URES 2 and 3.

FIGURE 2 shows valve 14 in its de-energized position, wherein the valve connects the conduits 26 and 25 and cuts off the duct 24.

FIGURE 3 shows the valve 14 energized, a position in which the valve cuts off the conduit 25 and establishes a communication between the conduits 26 and 24.

The solenoid, not shown in detail, of the valve 14, and the motor of the compressor 11 are electrically connected to a feeding circuit exemplified in FIG. 4.

The motor 11 is fed by the main 30 via the thermostatic switch 40: this is intended to be installed in the freezer compartment or outside it and is closed when the sensed temperature is above a preselected threshold, whereas it is open at lower temperatures.

A thermostatic switch 41 is mounted in the refrigerator compartment: the main contact is closed at temperatures above a preselected threshold value of temperature and is opened at a lower temperature value.

The contact 3-2, when closed, feeds the compres sor motor and, when opened, (contact3-4) feeds the solenoid of valve 14.

With a circuit arrangement as shown and described herein, it is apparent that, when the temperature is too high in either compartment, the electric motor of the compressor is started.

If the temperature in the freezer is too high, but the temperature in the refrigerator is already sufficiently low (contact 3-2 of the thermostat 41 open), the valve 14 is in the position of FIGURE 3 and the evaporator 16, alone, is fed since the feed for evaporator 15 is cut off. It is thus prevented the shortcoming that the necessity of removing calories from the freezer compartment may depress too much and undesirably the temperature in the refrigerator compartment.

If the temperature, in the refrigerator compartment, attains too high a value (contact 3-2 of thermostat 41 closed), the compressor 11 is started, the valve 14 is set in the position of Figure 2 and the evaporator 15 is fed, the evaporator 16 being also fed due to the cascade arrangement of the two evaporators.

The result is thus a complementary withdrawal of heat from the freezer compartment, the latter, as a rule, requiring more frequent actions for maintaining the very low temperatures requested therefor: in the freezer no supercooling is to be feared, whereas, conversely, even temporary temperature rises would be highly undesirable.

Claims (4)

1. A refrigeration circuit in which a compressor sends the compressed refrigerating fluid to evaporators via a condenser, characterized in that said evaporators are two, the first for a refrigerator compartment and the second for a freezer compartment, the former discharging the fluid into the input to the latter, valve means connecting in alternate sequence the first and the second evaporator to the delivery side of the compressor, said valve means being driven by devices which are responsive to the temperature of the two compartments.

2. A machine according to claim 1, wherein said means are a valve which alternately driven cuts off in a first position the fluid flow from the compressor to the input of the second evaporator by connecting the latter to the discharge of the first evaporator or cuts off in its second position the feed to the first evaporator by connecting the input to the second evaporator to the compressor.

3. A machine according to claim 1, equipped with temperature responsive means for the refrigerator compartment, said means being adapted to start the compressor and to drive the valve in its first position when the temperature in the compartment is above a preselected threshold value, and to cut off the feed to the compressor while driving said valve to the second position thereof when said temperature is below the preselected threshold value.

4. A machine according to claim 1, equipped with means responsive to the temperature in the freezer compartment for starting the compressor whenever a temperature rise above the preselected value is sensed in the freezer compartment.