DE102014211133A1 - Refrigerating appliance and chiller for it - Google Patents

Abstract

A refrigerating machine for a household refrigerating appliance comprises a first and a second evaporator (4, 5), which are arranged together with a respective upstream throttle point (12, 26) in mutually parallel branches (16, 17) of a refrigerant circuit (15). At the outlet of the second evaporator (4) a check valve (13) is arranged. The first throttle (26) connected upstream of the first evaporator (5) can be switched between a high and a low flow rate.

Description

The present invention relates to a refrigeration appliance, in particular a domestic refrigeration appliance, and more particularly to the construction of a refrigerator which can be used in such a refrigeration appliance.

Domestic refrigerators with two held at different operating temperatures storage compartments such as a freezer and a normal refrigeration compartment and a refrigerator, each having a first evaporator for cooling the first storage compartment and a second evaporator for cooling the second storage compartment in parallel branches of a refrigerant circuit, are known in the art , In order to enable energy-efficient operation of such a refrigeration device, it is desirable to be able to set different evaporation temperatures in the evaporators, each adapted to the operating temperature of the compartment to be cooled by them. The prerequisite for this is that different pressures prevail in the evaporators. In order to maintain such different pressures, a check valve at the outlet of the second evaporator is known to provide a check valve which prevents steam from flowing from the first evaporator into the second and heats the compartment associated with the second evaporator by condensing in the second evaporator.

Although the check valve prevents a pressure increase in the second evaporator during a cooling phase of the first evaporator, but not a reduction in the pressure in the first evaporator to the pressure prevailing in the second evaporator evaporation pressure during a cooling phase of the latter. This has the consequence that after a cooling phase of the second evaporator of the first evaporator is substantially empty. If at the beginning of a new cooling phase of the first evaporator liquid refrigerant is introduced into this, initially only a small amount of liquid refrigerant of the suction power of the compressor is exposed, the pressure in the first evaporator remains low, and it sets an uneconomically low evaporation temperature. If the amount of liquid refrigerant in the first evaporator has grown far enough to maintain a higher evaporation pressure, the cooling phase of the first evaporator is usually already largely over. During a large part of the cooling phase of the first evaporator, the chiller therefore operates with less than optimal efficiency.

Object of the present invention is to improve the energy efficiency of a refrigerator with two storage compartments or a suitable for use in such a refrigerator chiller.

The object is achieved on the one hand by a check valve is arranged in a chiller with a first and a second evaporator, which are arranged together with one upstream throttle in mutually parallel branches of a refrigerant circuit, and at the outlet of the second evaporator, the first evaporator upstream first throttle point between a high and a low flow rate is switchable. By selecting the high flow rate each at the beginning of a cooling period of the first evaporator, the amount of liquid refrigerant in the first evaporator can be rapidly increased at the beginning of the cooling phase, so that the period of low evaporation temperature at the beginning of the cooling phase is shortened and quickly reaches an energy-efficient operating state becomes.

Preferably, the chiller includes a control unit configured to set cooling phases of the first evaporator in which refrigerant flows through the first throttle and idle periods of the first evaporator in which no refrigerant flows through the first throttle, and the first throttle at the beginning of each cooling phase to switch to the high flow rate.

Switching the first throttle point to the low flow rate can be automatically timed, if a predetermined period of time has elapsed since the beginning of a cooling phase of the first evaporator.

Alternatively, the refrigerator may include a temperature sensor for detecting the refrigerant temperature disposed at the refrigerant circuit downstream of the first evaporator, and the throttle may be controlled by this temperature sensor.

In particular, the throttle body may be configured to switch to the low flow rate when a drop in the detected temperature below a threshold indicates that the ratio of heat to be absorbed by the refrigerant in the first evaporator to the amount of liquid refrigerant contained in the evaporator is low.

To allow switching between different flow rates, the restriction may include an expansion valve.

Alternatively, the throttle may include two parallel bottlenecks and a valve for controlling the distribution of the refrigerant to the two bottlenecks. The valve may be a directional valve, which acts on either one or the other of the two bottlenecks with the refrigerant, in which case the bottlenecks have to have different geometries in order to realize the high and the low flow rate. The valve could also be a check valve, which is arranged in the line only one of the two bottlenecks and this locks or releases. Thus, the low flow rate is realized when the refrigerant can only circulate through the other bottleneck, and the high flow rate is achieved when it circulates through both bottlenecks in parallel.

In order to be able to realize a lower evaporation pressure in the second evaporator than in the first, a throttling point upstream of the second evaporator can have a flow rate which is even lower than the low flow rate of the first throttling point.

In order to selectively pressurize the first or the second evaporator with refrigerant, a valve assembly is generally upstream of the parallel branches of the refrigerant circuit, which is switchable between a position in which only the first branch can be acted upon with refrigerant, and a position in which exclusively the second branch can be acted upon by refrigerant. Preferably, the valve assembly may still have a blocking position in which both branches are cut off from the supply of refrigerant. Such a blocking position makes it possible to hold refrigerant, which is present at the end of a cooling phase in a high pressure region of the refrigerant circuit, there and thus to prevent a backflow of warm refrigerant from the high pressure region into the evaporator.

The object is further achieved by a refrigeration device, in particular a domestic refrigerator, with a refrigerator as described above, a first storage compartment cooled by the first evaporator and a second storage compartment cooled by the second evaporator.

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

1 a schematic representation of a household refrigerator according to a first embodiment of the invention;

2 a schematic representation according to a second embodiment; and

3 a schematic representation according to a third embodiment.

This in 1 Household refrigeration unit shown is a combination refrigerator with two different temperature storage bins, here a freezer 1 and a normal refrigerator 2 in a thermally insulated housing 3 are housed. Each storage compartment 1 . 2 is an evaporator 4 respectively. 5 assigned. The evaporators can, as indicated, be Coldwall evaporators, other evaporator types are also considered.

The evaporators 4 . 5 are part of a chiller, which also has a compressor 6 , a liquefier 7 , Directional valves 8th . 9 and capillaries 10 . 11 . 12 and a check valve 13 includes. A refrigerant line 15 runs from an outlet of the compressor 6 to the directional valve 8th and shares in a freezer branch 16 at which the capillary 12 , the evaporator 4 and the check valve 13 are arranged, and a normal refrigerator compartment branch 17 at which the directional control valve 9 , the capillaries 10 . 11 and the evaporator 5 are arranged. At a merger point 18 in front of the suction connection of the compressor 6 meet the branches 16 . 17 again on each other. The directional valve 8th has a position in which the branch 16 supplied with refrigerant, a position in which the branch 17 is supplied with refrigerant, and possibly a blocking position, in which it is to neither of the two branches 16 . 17 is permeable.

At the subjects 1 . 2 are arranged in a conventional manner in the figure, not shown, temperature sensors and with an electronic control unit 14 connected by comparing the detected temperatures with set target temperatures of the subjects 1 . 2 possible cooling demand is determined and if there is a need for cooling the compressor 6 turns on and a position of the directional control valve 8th adjusts in which each refrigerated compartment 1 or 2 is charged with liquid refrigerant.

The directional valve 9 and the capillaries 10 . 11 form a throttle point 26 with controllable flow rate by the directional control valve 9 between a position in which there is the supply of liquid refrigerant to the evaporator 5 of the standard refrigerator compartment 2 over the capillary 10 allows, and a position in which it supplies the evaporator 5 over the capillary 11 allows, is switchable. The flow rate of the capillary 11 is smaller than that of the capillary 10 and dimensioned to a long-lasting operation of the compressor 6 without overfilling the evaporator 5 to allow.

If in the normal refrigerator 2 Cooling demand is determined, in most cases, the previously operated as the last evaporator of the evaporator 4 of the freezer compartment 1 been, leaving liquid refrigerant, resulting from an even earlier cooling phase of the evaporator 5 This is left behind during the cooling phase of the evaporator 4 through the compressor 6 has been essentially sucked off and the evaporator 5 practically empty. By the control unit 14 each before the start of a Cooling phase of the evaporator 5 the high flow rate capillary 10 in the path of the refrigerant, it reaches a fast filling of the evaporator 5 with liquid refrigerant, so that after a short time a high vapor pressure in the evaporator 5 and accordingly an evaporation temperature which is only a few degrees below the setpoint temperature of the normal refrigeration compartment 2 lies, stops. Once a sufficient filling of the evaporator 5 is achieved with liquid refrigerant throttles the control unit 14 the inflow of liquid refrigerant, passing through the directional valve 9 the capillary 11 Switches into the path of the refrigerant at a lower flow rate. This is an energy-efficient cooling operation of the normal refrigeration compartment 2 possible until the temperature sensor of the standard refrigerator compartment 2 indicates that the cooling demand is satisfied, and the control unit 14 the refrigerant supply to the evaporator 5 turns off again.

Switching from the capillary 10 on the capillary 11 at the directional valve 9 can from the control unit 14 in the simplest case timed, ie, assuming that a fixed period of refrigerant supply through the capillary 10 sufficient filling of the evaporator 5 with liquid refrigerant results, the control unit turns off 14 each time this period of time has passed to the capillary 11 around.

An alternative embodiment may result at the outlet of the evaporator 5 another temperature sensor 19 be provided to the temperature of the evaporator 5 sucked refrigerant to capture. If the temperature sensor 19 as shown in the figure, on the leg of the line 17 outside the evaporator 5 is arranged, it heats up in idle phases of the evaporator 5 , Cools as soon as the beginning of a cooling phase evaporation in the evaporator 5 begins, and passes through a minimum, since with increasing amount of the liquid refrigerant in the evaporator 5 during the cooling phase pressure and evaporation temperature rise there. If, after passing through this minimum, that of the temperature sensor 19 detected temperature exceeds a predetermined limit, this may be indicative of a sufficient filling of the evaporator 5 accepted and the directional control valve 9 on the capillary 11 be switched. It is also conceivable, a further drop in temperature after passing through the above-mentioned minimum as an indication of overfilling of the evaporator 5 to evaluate and then on the capillary 11 switch.

2 shows a partial representation of the refrigerator according to a second embodiment of the invention. Parts omitted in the figure of the refrigerator are with those of 1 identical. The throttle point 26 is here through the capillaries 10 . 11 , one to the capillaries 10 . 11 leading branch 21 and a shut-off valve 22 in one of the two from the junction 21 replaced outgoing line branches. One of the two capillaries 10 . 11 , which can have the same passage rates here, is constantly with the directional control valve 8th the other only when the shut-off valve 22 is open. So can by opening the shut-off valve 22 each at the beginning of a cooling phase of the evaporator 5 a fast filling can be achieved, and as soon as the filling is sufficient, by closing the shut-off valve 22 the inflow of liquid refrigerant can be reduced.

In the in 3 The embodiment shown is the throttle point 26 through an expansion valve 23 replaced with adjustable passage cross section. The passage cross section can, as indicated by a dashed line, the control by the control unit 14 be subject to, depending on since the beginning of a cooling phase of the evaporator 5 elapsed time or based on the output of the evaporator 5 detected refrigerant temperature, as above with respect to 1 described to be controlled. It is also conceivable here, the electronic temperature sensor 19 to be replaced by a hollow body filled with refrigerant 24 , the pressure of which depends on the temperature at the outlet of the evaporator 5 varies and over a pipeline 25 directly on a piston of the expansion valve 23 acts, which determines its passage cross-section.

LIST OF REFERENCE NUMBERS

1

 freezer

2

 Normal refrigeration compartment

3

 casing

4

 Evaporator

5

 Evaporator

6

 compressor

7

 condenser

8th

 way valve

9

 way valve

10

 capillary

11

 capillary

12

 capillary

13

 check valve

14

 control unit

15

 Refrigerant line

16

 freezer branch

17

 Normal refrigeration compartment branch

18

 rallying point

19

 temperature sensor

20

21

 branch

22

 shut-off valve

23

 expansion valve

24

 hollow body

25

 pipeline

26

 restriction

Claims (10)

Chiller with a first and a second evaporator ( 4 . 5 ), which together with an upstream throttle 26 . 12 ) in parallel branches ( 16 . 17 ) of a refrigerant circuit ( 15 ) are arranged, wherein at the outlet of the second evaporator ( 4 ) a check valve ( 13 ), characterized in that the first evaporator ( 5 ) upstream first throttle point ( 26 ) is switchable between a high and a low flow rate. Chiller according to claim 1, characterized in that a control unit ( 14 ), cooling phases of the first evaporator ( 5 ) in which refrigerant passes through the first restriction ( 26 ), and rest periods of the first evaporator ( 5 ) in which no refrigerant flows through the first restriction ( 26 ), and at the beginning of each cooling phase, the first throttle point ( 26 ) to switch to the high flow rate. Chiller according to claim 1 or 2, characterized in that the first throttle point ( 26 ) is set to switch to the low flow rate if, since the beginning of a cooling phase of the first evaporator ( 5 ) a predetermined period of time has elapsed. Chiller according to claim 1 or 2, characterized in that it comprises a temperature sensor ( 19 ) for detecting the refrigerant temperature downstream of the first evaporator ( 5 ) and the first throttle restriction ( 26 ) based on the temperature sensor ( 19 ) is controlled. Chiller according to claim 4, characterized in that the throttle point ( 26 ) is set to switch to the low flow rate when the detected temperature falls below a threshold value. Chiller according to one of the preceding claims, characterized in that the throttle point ( 26 ) an expansion valve ( 23 ). Chiller according to one of claims 1 to 5, characterized in that the throttle point ( 26 ) two parallel bottlenecks ( 10 . 11 ) and a valve ( 9 ; 22 ) for controlling the distribution of the refrigerant to the two bottlenecks ( 10 . 11 ). Chiller according to one of the preceding claims, characterized in that the second evaporator ( 4 ) upstream throttle point ( 12 ) has a flow rate that is less than the low flow rate of the first throttle point ( 26 ). Chiller according to one of the preceding claims, characterized in that the parallel branches ( 16 ; 17 ) a valve assembly ( 8th ) between a position in which only the first branch ( 17 ) can be acted upon with refrigerant, a position in which only the second branch ( 16 ) can be acted upon with refrigerant and a blocking position in which both branches ( 16 . 17 ) are cut off from the supply of refrigerant, is switchable. Refrigerating appliance, in particular household refrigerating appliance, with a refrigerator according to one of the preceding claims, one of the first evaporator ( 5 ) cooled first storage compartment ( 2 ) and one from the second evaporator ( 4 ) cooled second storage compartment ( 1 ).

Images