EP0547310B1 - Two-temperature household refrigeration apparatus with a single cycle - Google Patents

Description

The invention relates to a two-temperature single-circuit refrigerator for the household, comprising an evaporator which essentially has two sections and forms a system of connected refrigerant channels, the first section of which forms a ceiling, an upright wall and a bottom of a freezer compartment, as a room evaporator in one section serving below the freezer compartment is connected upstream, the refrigerant supplied from the injection point into the channel system flows from a downward-running supply channel in the upright wall of the first evaporator section into a channel arranged in a meandering manner in the bottom of the freezer section, which channel flows into a channel in the upright wall of the first evaporator section leading discharge channel opens, which merges in the ceiling in a channel arrangement laid in turns, the output of which is directed downward in the upright wall with the input d it is connected to the second section forming the space evaporator.

Due to the peculiar series connection of such an evaporator construction between freezer compartment evaporator and refrigerator compartment evaporator, the freezer compartment evaporator being connected upstream of the refrigerator compartment evaporator, it can happen that even during the defrosting phase with the refrigerant compressor at a standstill, as a result of pressure differences prevailing in the refrigerant system, drops of liquid refrigerant evaporator from the refrigeration compartment evaporator to the common refrigeration compartment evaporator from the refrigeration unit Connection point can be pressed. When the liquid refrigerant enters the connection point to the warmer refrigerator compartment evaporator, the refrigerant evaporates there immediately, so that the temperature at this point does not exceed the melting temperature of the ice until the refrigerant compressor starts up again. This results in permanent icing at the critical connection point, which increases over time, the removal of which would mean the cooling device being temporarily shut down.

From DE-PS 31 34 300 an evaporator for a two-temperature single-circuit refrigerator is known, which has a freezer compartment and a section associated with its normal refrigerator compartment. The freezer evaporator upstream of the defrostable normal refrigerator compartment evaporator in the refrigerant circuit is formed from an upright wall provided with refrigerant channels and two legs bent in the same direction, which serve as a ceiling and a floor and are also equipped with refrigerant channels.

The channel structure in the bottom of this evaporator essentially has three interconnected sections, each of which is formed from two large-volume pipelines communicating with one another via transverse channels, the predominant length of which is arranged perpendicular to the free end of the bottom. One of the three sections is connected on the outlet side in the floor to two parallel duct runs, which are connected to each other in the upright wall via a transverse duct and merge into a single refrigerant duct laid in turns in the ceiling.

Due to the channel arrangement of the evaporator, when the refrigerant compressor is at a standstill, a first separation between the gaseous and liquid components of the refrigerant flow in the floor and in the upright wall is to take place, the large-volume pipelines in the floor serving as collectors for the liquid refrigerant. A further separation of the gaseous from the liquid refrigerant should be achieved by the inclined arrangement of the ceiling to the upright wall, the liquid refrigerant flowing back into the bottom of the freezer compartment evaporator following gravity. In the event that refrigerant flows in from the condenser, pressure is exerted on the liquid refrigerant which has accumulated in the front region of the floor due to production and which completely fills the channels. Since the individual sections of the channel arrangement in the floor are always connected to one another only via a single line, the pressure inevitably propagates onto the section connected to the outlet side with the parallel channel lines and pushes the accumulated liquid volume into the parallel channel lines arranged in the upright wall. If refrigerant flows from the condenser to the evaporator over a longer period of time, For example, as a result of the cooling of the refrigerant compressor, there is a risk that, despite the elaborate measures taken, grafts of liquid refrigerant will get to the connection point between the freezer compartment evaporator and the normal refrigeration compartment evaporator and evaporate there, so that the connection point is constantly iced up despite cyclical defrosting.

The invention has for its object to design the channel system in the freezer compartment evaporator in cooling devices of the type mentioned so that it is ensured at all times that no liquid refrigerant reaches the connection point between the freezer compartment evaporator and the refrigerator compartment evaporator during the downtime of the refrigerant compressor.

The object is achieved according to the invention in that the feed channel and the discharge channel are connected via a bypass arranged at a distance above the bottom of the first evaporator section, which has an increased flow resistance in the bottom compared to the bridged channel arrangement.

The solution according to the invention ensures that the pressure generated by the refrigerant flowing in from the condenser to the evaporator when the refrigerant compressor is at a standstill, for example caused by the cooling refrigerant compressor, is reduced without this influencing the liquid refrigerant resting in the bottom of the freezer compartment evaporator can, so that no liquid refrigerant reaches the connection point between the two evaporator sections even over long periods of time. Furthermore, the Cooling capacity in the cooling compartments is not affected by the bypass. In addition, standing time noises caused by air bubbles rising from the liquid refrigerant are significantly reduced.

According to a further advantageous embodiment of the object of the invention, it is provided that the bypass connecting the feed channel to the discharge channel and having a higher flow resistance is arranged in the ceiling of the first evaporator section.

A solution according to these features has the advantage that the pressure propagating from the condenser to the evaporator is diverted to the cooling compartment evaporator shortly after it enters the ceiling.

According to a further advantageous embodiment of the subject matter of the invention, it is provided that the increased flow resistance of the bypass is determined by a corresponding length arranged in turns and / or in particular by a reduction in cross section.

This solution has the advantage that the parameters defining the flow resistance are simple and economical to manufacture and also have a good, constant accuracy.

Without production-related, complex additional measures and within narrow tolerance limits, the channels of the bypass are sufficiently large when the flow resistance differs from the rest of the channel arrangement if, according to a preferred embodiment of the object of the invention it is provided that the channel cross sections of the bypass and the feed channel are in a ratio of 1: 3 to 1: 7, but preferably in a ratio of 1: 5.

According to a next preferred embodiment of the subject matter of the invention, it is provided that the feed channel has a main channel and at least one secondary channel running parallel thereto, the main channel being equipped with transverse channels which branch off approximately perpendicularly from it and are spaced apart from one another and which is fluidically connected to the secondary channel connect.

Such a solution has the advantage that an uneven distribution, which is essentially independent of the channel cross-section of the main channel and the feed channel, occurs as a result of the inertia of the refrigerant flowing into the feed channel, so that essentially the main channel is exposed to liquid refrigerant, while the secondary channel has hardly any liquid Refrigerant leads.

According to a further preferred embodiment of the subject matter of the invention, it is provided that the discharge channel has a main channel and at least one secondary channel running parallel to it, the main channel being equipped with transverse channels which branch off approximately perpendicularly from it and are spaced apart from one another and which is fluidically connected to the secondary channel connect.

The advantage here is that, with simple means, according to the laws of gravity, gaseous inclusions can escape within the liquid refrigerant stream without them pushing grafts of liquid refrigerant in front of them.

According to a further preferred embodiment of the object of the invention, it is provided that both the transverse channels of the feed channel and those of the discharge channel are at a distance from one another which is greater than the height of the upright wall, but is preferably dimensioned such that the transverse channels are in the vicinity of the transition lie on the upright wall in the floor or in the ceiling.

The solution has the advantage that both the feed channel and the discharge channel are guided in two strands over the bending zones of the U-shaped evaporator section, so that the cross section of the two channels can be reduced compared to a single channel, whereby the influence on their flow cross section by constriction is considerably reduced , and thus the transitions do not have a flow-restricting effect on the circulating refrigerant.

The channel cross sections of the supply and discharge channels are particularly expedient if, according to a preferred embodiment of the subject matter of the invention, it is provided that the main and the secondary channel of the supply and discharge channels have the same cross section.

The liquid refrigerant is significantly more difficult to enter the bypass if, according to an advantageous embodiment of the subject of the invention, that the transverse channel of the supply channel branches in the ceiling with the bypass in such a way that the refrigerant can enter the bypass after a sharp deflection.

According to a next preferred embodiment of the object of the invention it is provided that the main channel of the discharge channel downstream of its branching transverse channel in the ceiling merges into a collector-shaped channel section provided with button-like impressions, which is arranged parallel to the free end of the ceiling.

The advantage of such a solution is that, in addition to a further possibility of separating the gaseous liquid from the liquid refrigerant, additional collection volume is created for liquid plugs which may be pressed out of the ground into the ceiling and then evaporate there because of the slightly higher temperature than that in the ground and do not reach the connection point between the freezer compartment and the refrigerator compartment evaporator.

According to a further advantageous embodiment of the subject matter of the invention, it is provided that the feed channel merges into a channel piece in the area after its entry into the ground, the channel section opening into at least two mutually parallel, opening into the discharge channel, essentially the same cross section as the channel piece having duct sections branched, the predominant length of which is arranged parallel to the free end of the base and which cross at least in a common duct bed downstream of the branching.

A solution corresponding to these features on the one hand has a favorable effect on the separation of the liquid and the gaseous refrigerant, and on the other hand it is ensured in a simple manner that sufficient volume is available in the standstill phase of the refrigerant compressor for the liquid refrigerant collecting in the soil.

The arrangement of the feed and discharge channel in the upright wall is particularly expedient and space-saving if, according to a preferred embodiment of the object of the invention, it is provided that the channels are arranged vertically in the upright wall.

A channel system of a freezer evaporator provides additional security in order to prevent liquid refrigerant from being able to pass from the freezer compartment evaporator into the refrigerator compartment evaporator during the standstill phase of the refrigerant compressor, if, according to an advantageous embodiment of the object of the invention, it is provided that the ceiling duct arrangement connected downstream of the floor arrangement is in relation to the latter has lower capacity for liquid refrigerant, but has a larger capacity compared to the ceiling channel arrangement upstream of the floor.

Fig. 1

im Ausschnitt einen Zweitemperaturen-Einkreiskühlschrank, mit einem Gefrierfach und einem unterhalb diesem angeordneten Normalkühlfach, teilweise geschnitten, um dessen Verdampfersystem sichtbar zu machen, in raumbildlicher Darstellung,

Fig. 2

das als walzgeschweißte Platine ausgebildete Verdampfersystem des Kühlschranks entsprechend Fig. 1 in abgewickelter Darstellung,

Fig. 3

in Ansicht von oben, die mit den Ausprägungen für die Kältemittelkanäle versehene Seite des einbaufertig geformten Verdampfersystems in raumbildlicher Darstellung,

Fig. 4

in Ansicht von unten den als Gefrierfachverdampfer ausgebildeten Abschnitt des Verdampfersystems in raumbildlicher Darstellung.

The invention is explained in a description below with reference to an embodiment shown in simplified form in the drawing. Show it:

Fig. 1

in the cutout a two-temperature single-circuit refrigerator, with a freezer compartment and a normal refrigerator compartment arranged below it, partially cut to make its evaporator system visible, in spatial representation,

Fig. 2

the developed as a roll-welded circuit board evaporator system of the refrigerator according to FIG. 1 in a developed representation,

Fig. 3

in a view from above, the side of the ready-to-install shaped evaporator system provided with the characteristics for the refrigerant channels in a spatial representation,

Fig. 4

in view from below the section of the evaporator system designed as a freezer compartment evaporator in a spatial representation.

1, a two-temperature single-circuit refrigerator 10 is shown, which, as usual, is equipped with an overhead freezer compartment 11 and a normal refrigerator compartment 13 arranged underneath and separated from this by a heat-insulating intermediate wall 12. The side walls of the normal cooling compartment 13 are provided with grooves 14 formed in the inner container of the refrigerator 10 for inserting shelves (not shown).

The refrigerator 10, which is equipped with a refrigerant compressor (not shown), is equipped with an evaporator 15 having two sections A and B and forming a system of coherent refrigerant channels, which is formed from two circuit boards connected by roller welding and receiving the refrigerant channels between them.

The section of the evaporator 15, designated A, assigned to the freezer compartment 11 has a ceiling 16, an upright wall 17 serving as the rear wall and a bottom 18, which are formed from a one-piece circuit board section. Below the freezer compartment 11, in the normal cooling compartment 13, the section B downstream of section A is arranged in the refrigerant circuit of the evaporator 15 and is designed as a defrostable room evaporator.

The sections A and B of the evaporator 15 are connected to one another by a web-like connecting bridge 19 (cf. in particular FIGS. 2 and 3).

The evaporator 15 shown in the development in FIG. 2 from a roll-welded circuit board is formed into a U-shaped profile, shown in particular in FIG. 1, by bending along the bending zones located between the individual sections and delimited by dash-dotted lines both ends are open. The legs of the U-shaped profile bent in the same direction from the upright wall 17 have a slightly larger angle than 90 ° with respect to the upright wall 17 after the bending process.

In a manner known per se, the liquid refrigerant is fed to the duct system of the evaporator 15 via a throttle tube 21 which is installed in a suction pipe 20 and is arranged in the ceiling 16 (cf. FIGS. 2 and 3 in this regard). The refrigerant flows through the ceiling 16 in a large-volume channel part 22 which runs close to the transition to the upright wall 17 and which is still in the ceiling 16, outside the bending zone, connects to a downwardly extending feed channel 23 arranged in the upright wall 17 of the first evaporator section (see also FIG. 3). The connection point between the channel part 22 and the feed channel 23, which has a main channel 24 and a secondary channel 25 running parallel thereto, is designed such that the channel routing of the channel part 22 continues seamlessly in the main channel 24. The main channel 24 and the secondary channel 25 have the same channel cross-section and are connected to one another in terms of flow technology with two transverse channels 26 which branch off perpendicularly from the main channel 24 and are arranged at a distance from one another and have a short channel length. The distance between the two transverse channels 26 branching off from the main channel 24 is such that the respective branch point from the main channel 24 lies outside the bending zones of the evaporator section denoted by A in its ceiling 16 or in its bottom 18 in the vicinity of the transitions to the upright wall 17 (See Fig. 3 and Fig. 4). Outside the bending zone, in the floor 18, near its transition to the upright wall, the main channel 24 of the feed channel 23 continues seamlessly in a channel piece 27. After a relatively short path, this branches symmetrically into two channels 28, which run parallel to one another and run in a meandering manner in the bottom 18, each having the same channel cross section of the channel piece 17, the predominant length of which is arranged parallel to the free end of the bottom. Downstream after the branching, the channels 28 are briefly combined in a common channel bed 29, but then separated again. For this purpose, the channel bed 29 divides both upstream and downstream symmetrically with a channel cross section corresponding to the channels 28 in each case. The channels 28 are at their output end connected in the bottom 18 by an essentially circular connection piece 30, which is arranged outside the bending zone, to a discharge channel 31 rising vertically in the upright wall 17 of the first evaporator section.

The discharge channel 31, like the feed channel 23, has a main channel 32 and a secondary channel 33 running parallel thereto, which is arranged adjacent to the secondary channel 25 of the feed channel 23. Just like the main channel 24 of the feed channel 23, the main channel 32 of the discharge channel 31 is also equipped with transverse channels 34 branching perpendicularly from it, but the transverse channel arranged in the bottom 18 is formed by an annular sector of the annular connecting piece 30. The transverse channels 34 are arranged at a distance from one another which is greater than the height of the upright wall 17 and corresponds to the distance between the transverse channels 26 of the feed channel 23.

The outlet-side end of the feed channel 23 is connected to the outlet-side end of the discharge channel 31 in the ceiling 16 which is arranged directly next to it, by means of a bypass 35 which has an increased flow resistance and bridges the channel arrangement in the bottom 18, the bypass 35 at the junction of the transverse channels in the Secondary channels are connected to this. The increased flow resistance of the bypass 35 is achieved, in addition to a corresponding length arranged in turns, additionally by a reduced channel cross section compared to the channels of the feed channel 23 and the discharge channel 31, the ratio of the channel cross sections between the bypass 35 and the main or secondary channels of the Feed channel 23 or the discharge channel 31 is approximately 1: 5.

Approximately at the level of the connection point of the bypass 35 to the secondary duct 33 of the discharge duct 31, the cross section of its main duct 32 widens downstream after its branching transverse duct 34 in the ceiling 16, before being formed in a collector-like manner in a parallel to the free end of the ceiling 16 Channel section 36 merges, the volume of which is interrupted by button-like impressions 37 (see FIGS. 2 and 3).

The channel section 36 designed in the manner of a collector belongs to a channel arrangement which is laid in turns in the ceiling 16 and has the same channel cross section as the expanded main channel 32. The outlet of the channel arrangement is connected to a channel line 38, which is directed downward on the connecting bridge 19 and is designed as a double channel across the bending zones, with the input of the section, which is not explained in more detail and which forms the space evaporator and is designated by B (see also FIG 3).

When the refrigerant compressor is in operation, the design of the feed channel 23 ensures that the liquid refrigerant flows mainly in its main channel 24 and, in relation thereto, a small proportion in its secondary channel 25. As a result of this measure, the bypass 35 connected to the secondary duct 25, which is also equipped with an increased flow resistance in comparison to the duct cross-sections of the feed duct 23, is only acted on with small amounts of liquid refrigerant, so that there is no loss of performance in the freezer compartment evaporator during the running time of the refrigerant compressor .

In the standstill phase of the refrigerant compressor, the pressure drop between the condenser and evaporator, which e.g. created by the cooling compressor, and which usually manifests itself in the afterflow of essentially gaseous refrigerant from the condenser to the evaporator, is reduced via the bypass 35. Due to the fact that the flow resistance for the medium flowing in the bypass 35 is less than the resistance that the liquid accumulated in the bottom 18 of the freezer evaporator during the standstill phase of the refrigerant compressor opposes the pressure of the flowing medium during its movement, the inflowing refrigerant becomes transferred to the backspace evaporator. The liquid refrigerant accumulated in the bottom 18 thus remains at rest.

If individual liquid fractions act on the refrigerant flow flowing from the condenser into the evaporator, these are evaporated at the latest in the channel section 36 provided with the button-like impressions, unless this has already been done in the feed line to the bypass 35.

Claims (13)

1. Two-temperature single-circuit refrigerator for the household, with an evaporator (15), which displays substantially two sections and forms a system of contiguous refrigerant channels and the first section (A) of which forms a ceiling (16), an upright wall (17) and a base (18) of a freezing compartment and is connected upstream of its second section (B) serving as space evaporator in a normal cooling compartment underneath the freezing compartment, wherein the refrigerant, which is fed into the channel system from an injection point, flows from a feed channel (23), which extends downwardly in the upright wall (17) of the first evaporator section (A), into a channel (28),which is laid in meander shape at the base (18) of the freezing compartment and opens into a discharge channel (31), which rises in the upright wall (17) of the first evaporator section (A) and passes over in the ceiling (16) into a channel arrangement which is laid in coils and the exit of which is connected with entry of the second section (B), which forms the entry of the space evaporator, by a channel strand (38), which is directed downwardly in the upright wall (17), characterised thereby, that the feed channel (23) and the discharge channel (31) are connected by way of a bypass (35), which is arranged at a spacing above the base (18) of the first evaporator section (A) and which by comparison with the bridged-over channel arrangement in the base (18) displays an increased flow resistance.
2. Two-temperature single-circuit refrigerator according to claim 1, characterised thereby, that the bypass (35), which connects the feed channel (23) with the discharge channel (31) and displays a higher flow resistance, is arranged in the ceiling (16) of the first evaporator section (A).
3. Two-temperature single-circuit refrigerator according to claim 1 or 2, characterised thereby, that the increased flow resistance of the bypass (35) is determined by an appropriate length arranged in coils and/or particularly by a reduction in cross-section.
4. Two-temperature single-circuit refrigerator according to claim 3, characterised thereby, that the channel cross-sections of the bypass (35) and of the feed channel (23) are in a ratio in the range of 1:3 to 1:7, preferably however 1.5.
5. Two-temperature single-circuit refrigerator according to one of the claims 1 to 4, characterised thereby, that the feed channel (23) displays a main channel (24) and at least one secondary channel (25) extending parallelly thereto, wherein the main channel (24) is equipped with transverse channels (26), which branch off from it nearly perpendicularly, are arranged at a spacing one from the other and connect it with the secondary channel (25) in terms of flow technique.
6. Two-temperature single-circuit refrigerator according to one of the claims 1 to 4, characterised thereby, that the discharge channel (31) displays a main channel (32) and at least one secondary channel (33) extending parallelly thereto, wherein the main channel (32) is equipped with transverse channels (34), which branch off from it nearly perpendicularly, are arranged at a spacing one from the other and connect it with the secondary channel (33) in terms of flow technique.
7. Two-temperature single-circuit refrigerator according to claim 6, characterised thereby, that the transverse channels (26) of the feed channel (23) as well as also the transverse channels (34) of the discharge channel (31) display a spacing one among the other, which is greater than the height of the upright wall (17), but is preferably so dimensioned that the transverse channels (26, 34) lie in either the base (18) or the ceiling (16) near to the transition to the upright wall (17).
8. Two-temperature single-circuit refrigerator according to claim 6 or 7, characterised thereby, that the main channel (24, 32) and the secondary channel (25, 33) respectively of the feed channel (23) and the discharge channel (31) display equal cross-sections.
9. Two-temperature single-circuit refrigerator according to one of the claims 5 to 8, characterised thereby, that the transverse channel (26) of the feed channel (23) is branched by the bypass (35) in the ceiling (16) in such a manner that the refrigerant is capable of entering into the bypass (35) after a sharp deflection.
10. Two-temperature single-circuit refrigerator according to one of the claims 6 to 9, characterised thereby, that the main channel (32) of the discharge channel (31) downstream of its branching-off transverse channel (33) passes over in the ceiling (16) into a channel portion (36), which is constructed in the manner of a collector, is provided with button-like indentations and is arranged parallelly to the free end of the ceiling (16).
11. Two-temperature single-circuit refrigerator according to one of the claims 1 to 10, characterised thereby, that the feed channel (23) in the region downstream of its entry into the base (18) passes over into a channel member (27), which branches out into at least two mutually parallel channels (28), which open into the discharge channel (31) and each display substantially the same cross-section as the channel member (27) and the predominant length of which is arranged parallelly to the free end of the base (18) and which cross over in at least one common channel (29) downstream of the branching.
12. Two-temperature single-circuit refrigerator according to one of the claims 1 to 11, characterised thereby, that the feed channel (23) and the discharge channel (31) are arranged vertically in the upright wall (17).
13. Two-temperature single-circuit refrigerator according to one of the claims 1 to 12, characterised thereby, that the ceiling channel arrangement connected downstream of the base channel arrangement by comparison therewith displays a smaller holding capacity for liquid refrigerant, but has a greater holding capacity by comparison with the ceiling channel arrangement connected upstream of the base (18).

Images