WO2014089655A1

WO2014089655A1 - An electric cooling system

Info

Publication number: WO2014089655A1
Application number: PCT/BR2013/000554
Authority: WO
Inventors: Flavio J.H. KALLUF; Felipe Augusto VON FRÜHAUF
Original assignee: Whirlpool S.A.
Priority date: 2012-12-11
Filing date: 2013-12-11
Publication date: 2014-06-19
Also published as: BR102012031607A2

Abstract

The present invention relates to an electric cooling system (1) comprising at least one low-power transformer (3) provided with a primary electric terminal (5) and a secondary electric terminal (6), a cooling equipment (7) fed by a network voltage (2), and a hermetic compressor provided with a pressure relief system (8). The electric cooling system (1 ) is configured so that the low-power transformer (3) is electrically connectable to the cooling equipment (7) and to the hermetic compressor provided with a pressure relief system (8), wherein the primary electric terminal (5) is electrically connectable to the cooling equipment (7) and the secondary electric terminal (6) is electrically connectable to the hermetic compressor provided with the pressure relief system (8).

Description

Specification of the Patent of Invention for: "AN ELECTRIC COOLING SYSTEM"

The present invention relates to an electric cooling system provided with bivolt cooling equipment of, a low-power transformer and of a compressor with pressure relief.

Description of the prior art

Electric cooling systems constitute a way to feed electricity to a cooling piece of equipment, such as an ice-box, a horizontal/vertical freezer and an air-conditioner, such equipment being provided with a hermetic com- pressor.

Hermetic cooling compressors usually do not have flexibility with respect to the feed voltage, the latter having to be 127VAC or 220VAC, wherein, depending on the location and conditions of the electrical facilities of the generation, transmission and distribution of electric energy, such feed values may undergo oscillations of up to ± 25% of the nominal feed value. These oscillations end up damaging the hermetic compressor and prevent the cooling equipment from operating at its optimum performance conditions.

With a view to prevent replacement of the hermetic compressor, or even the whole cooling system in cases where it is necessary to alter the feed voltage of the equipment, the use of voltage transformers came up as an apparently feasible alternative, since the use of transformers enable electric connection of the system on both 127VAC and 220VAC.

Transformers are electric devices that have the objective of transmitting electric energy or electric power from a circuit (terminal) to an- other, carrying out the conversion of voltage values and currents.

Structurally, a transformer comprises two electrically insulated coils, arranged around a common point (core). The basis principal of a transformer is to carry out transmission of energy from the first coil to the second coil, the first coil receiving energy from a source of energy, such as electric voltage supplied by the energy supply networks. On the other hand, the second coil supplies energy to a determined charge, such as a cooling item of equipment. The first coil and the second coil are usually called primary termi- nal of the transformer and secondary terminal of the transformer.

Supposing that the hermetic compressor has been designed for an electric feed of 220VAC and the voltage supplied by the network is of 127VAC, the use of a step up transformer (voltage values on the primary terminal of 127VAC and on the secondary terminal of 220VAC) would be acceptable, since the primary terminal of the transformer would be electrically connected and the network voltage (127VAC) and the secondary terminal of the transformer would be electrically connected to the cooling equipment and to the hermetic compressor, thus supplying 220VAC to the hermetic com- pressor, according to its nominal specifications.

The same thing occurs if the hermetic compressor is designed for electric feed of 127VC and the network voltage is 220VAC. In this case, one should use a step down transformer, where the voltage on the primary terminal of the transformer will be of 220VAC and the voltage on the second- ary terminal (connected to the hermetic compressor) of the transformer will be of 127 VAC, according to specifications..

In spite of enabling the electric connection of the cooling equipment and of the hermetic compressor for network voltage values of both 127VAC and 220VAC, the use of transformers has a few disadvantages, as set forth hereinafter.

As soon as it is connected between the energy distributing network and the cooling equipment, the transformer, be it a step up or step down one, should be kept permanently energized (on), regardless of whether the hermetic compressor is operating or not. In this way, the consumption of energy tends to increase significantly. Additionally, if the transformer remains connected to the network by a long period of time uninterruptedly, there is the possibility that it will undergo overheating on the coils of the primary terminal and of the secondary terminal, and such overheating may damage the transformer and affect its capability of converting energy, which will damage both the hermetic compressor and the cooling equipment.

Another obstacle existing when one uses transformers connected to the energy distributing network and the cooling equipment consists of the power demanded by the transformer at the moment of starting the hermetic compressor. As known in the prior art, hermetic compressors used on cooling equipment do not operate continuously, that means, a hermetic compressor will only act if the temperature of the cooling equipment needs to reach a determined value. So, at the moment when the compressor starts its operation, the required starting power will be a few times higher than the power required during normal operation of the compressor, this power being called steady-state power.

Since the transformer is electrically connected to the cooling equipment and to the hermetic compressor, the latter should be designed and specified so as to be capable of supplying the starting power required for starting the compressor, so that the transformer should be specified to have nominal power values equivalent to the starting power of the hermetic compressor, not a nominal power equivalent to the steady-state power.

In a practical example, one has a hermetic compressor used on household refrigerators, the compressor having a nominal power of approximately 100W, such compressor will require a starting power of about 2000VA. So, one should use a high-power transformer, capable of standing the starting power of the compressor, thus increasing the total cost of the system.

With a view to overcome the problems mentioned before and known from the prior art, the present invention describes an electric cooling system that makes use of a hermetic cooling compressor provided with a start-pressure relief system. Additionally, the electric cooling system de- scribed in the present invention uses a transformer of low nominal power (lower than 000VA in the case of the above example), such transformer being capable of standing integrally the starting power required by the compressor, without causing any damage to the system and to the cooling equipment.

The start-pressure relief system provides to the hermetic compressor with a reduced starting nominal power if compared with a hermetic compressor without pressure relief. In this way, the transformer used in the electric cooling system may have a lower nominal power if compared with the transformer used in conjunction with a hermetic compressor without pressure relief.

Pressure relief systems may be of various types, such as de- scribed in patent document US 2010/0329894, in which one describes a pressure relief pressure system that operates through control of valves, such valves being closed when the compressor is operating and open when the compressor is not in operation. With the system described in US 2010/0329894, the torque required for carrying out the start of the compres- sor is reduced and, as a result, its nominal starting power as well.

Other pressure relief systems that make use of additional valves are known from the prior art, such systems being described in documents US 7,721 ,757 and US 2005/0066673 and still in the case of the international patent WO 2010/060169. Further, pressure relief systems may be of other types, as for instance, those that use some type of wedge on at the suction valve of the hermetic compressor or still those that make use of an electromagnetic structure to provide interruption of the gas flow in the compressor.

Thus, since the electric cooling system described in the present invention makes use of an hermetic compressor with start pressure relief, it reduces the torque required for starting the compressor and, as a result, makes the use of a low-power transformer feasible.

Additionally, the electric cooling system described in the present invention reduces the total cost of the system and reduces the residual power of the transformer, since the latter will only operate in conjunction with the hermetic compressor. This is because, unlike the electric systems known from the prior art, the low-power transformer and the hermeticcompressor will be electrically energized through the cooling equipment, not through the network voltage.

Further, the electric cooling system described in the present in- vention provides the possibility that some loads of the refrigerator (electronic board, ventilators and illuminating lamps) will be electrically energized through the secondary electric terminal of the transformer. Objectives of the invention

It is an objective of the present invention to provide an electric cooling system comprising a hermetic compressor provided with a start pressure relief system and with a low-power transformer.

The present invention also has the objective of providing an electric cooling system in which the low-power transformer is electrically connected to the cooling equipment and to the hermetic compressor.

Additionally, it is an objective of the present invention to provide an electric cooling system in which the low-power transformer will only oper- ate when the hermetic compressor is in operation.

It is also an objective of the present invention to provide an electric cooling system in which determined loads of the cooling equipment may be electrically energized through the secondary electric terminal of the low- power transformer.

An additional objective of the present invention is to provide an electric cooling system with cooling equipment which may be fed by network voltage values of both 127VAC ± 5% and 220VAC ± 5%.

Brief description of the invention

The present invention relates to an electric cooling system con- figured so as to comprise at least one low-power transformer comprising a primary electric terminal and a secondary electric terminal, the cooling equipment being fed by a network voltage, and the hermetic compressor being provided with a pressure relief system. The electric cooling system is configured so that the low-power transformer will be electrically connectable to the cooling equipment and to the hermetic compressor provided with a pressure relief system. The primary electric terminal is electrically connectable to the cooling equipment and the secondary electric terminal is electrically connectable to the hermetic compressor provided with a pressure relief system. Brief description of the drawings

The present invention will now be described in greater detail with reference to the drawings attached, in which:

Figure 1 is a representation of an electric cooling system known from the prior art, in which figure 1A represents an electric system in which the network voltage is 220VAC ± 15% and figure 1 B represents an electric system in which the network voltage is 127VAC ± 15%;

Figure 2 represents a power x rotation graph showing a compari- son between the starting power and the steady-state power of a hermetic cooling compressor without a pressure relief system;

Figure 3 is the electric cooling system proposed in the present invention, considering the network voltage of 22VAC ± 15%;

Figure 4 represents the electric cooling system proposed in the present invention, considering the network voltage of 127VAC ± 15%;

Figure 5 represents an alternative construction of the electric cooling system 1 described in the present invention;

Figure 6 represents an alternative construction of the electric cooling system 1 described in the present invention, considering the network voltage of 127VAC ± 15%;

Figure 7 represents an alternative construction of the electric cooling system 1 described in the present invention, considering the network voltage of 220VAC ± 15%.

Detailed description of the figures

Figures 1A and 1B are a representation of an electric cooling system 3 known from the prior art. As can be observed, such system uses a high-power transformer 11 having the objective of providing greater flexibility of electrically feeding the hermetic compressor 12 of the cooling equipment 7.

If it is necessary to use a hermetic compressor 12 specified for operation on 220VAC at a network voltage 2 equal to 127VAC, as shown in figure 1B, one uses a high-power voltage step up transformer 11 , with voltage values at the primary terminal of 127VAC and voltage values at the secondary terminal of 220VAC. If the network voltage 2 is of 220VAC and the hermetic compressor 12 is specified for operation on 127VAC, one uses a high-power voltage step down transformer 11 , as shown in figure 1 A.

Due to the fact that the hermetic compressor 12 is not provided with a start pressure relief system, it is necessary that the high-pressure transformer 11 should be configured so as to meet the starting power values of the compressor, and this power may reach values of 2000VA for hermetic compressors used on household refrigerators, such a value being much higher than the nominal steady-state power of the hermetic compressor 12. Such relationship between the starting power values and the steady-state power of the hermetic compressor are better observed upon analyzing the graph shown in figure 2.

Figure 3 shows an electric cooling system 1 as proposed in the present invention, in which the hermetic compressor provided with a pressure relief system 8 is specified with nominal feed voltage of 127VAC and the network voltage 2 is of 220VAC.

One observes in this figure that, unlike what is shown in figures 1A and 1B, in the electric cooling system 1 of this invention the network volt- age 2 is electrically connected to the cooling equipment 7, that is, the cooling equipment is electrically energized by the network voltage 2. In order for this to be possible, it is necessary that the cooling equipment 7 should be bivolt, that is, the cooling equipment 7 should be able to work with network voltage values 2 of both 127VAC ± and 220VAC ± 15%. It is important to point out that, in the electric cooling system 1 shown in figure 3, the hermetic compressor provided with a pressure relief system 8 is specified for an electric feed voltage of 127VAC and, as mentioned, the cooling equipment 7 and its loads (electronic board, defrost heater element, ventilators and illuminating lamp) may be electrically fed by voltage values of both 127VAC AND 220VAC.

For the electrical feed of the hermetic compressor 8, one should use a low-power voltage step down transformer 3, so that the electric voltage at the primary electric terminal 5 of the transformer will be of 220VAC and the voltage at the secondary electric terminal 6 of the transformer will be of 127VAC.

Since the hermetic compressor 8 is provided with a starting pressure relief system (by using additional valves, wedges at the suction valve and use of electromagnetic structures), the transformer 3 used in the electric cooling system 1 shown in figure 3 is a low-power transformer 3 (with nominal power lower than or equal to 1000VA for household refrigerators), thus reducing the total cost of the electric cooling system 1.

For electrical feed of the hermetic compressor provided with a pressure relief system 8, one should connect the low-power transformer 3 to the cooling equipment 7, more specifically one should connect the primary electric terminal 5 of the transformer 3 to the cooling equipment 7 and the secondary electric terminal 6 of the transformer 3 to the hermetic compressor provided with a pressure relief system 8. This electric connection should be preferably inside the cooling equipment 7, so that it will not be necessary to add external components. In this way, in the electric cooling system 1 proposed in the present invention, the hermetic compressor provided with a pressure relief system 8 is electrically energized by the cooling equipment 7 after passage through the low-power transformer 3.

Thus, the low-power transformer 3 is electrically connected to the cooling equipment 7 and to the hermetic compressor provided with a pressure relief system 8. One observes that, due to such electric connection of the electric cooling system 1 described in the present invention, the low- power transformer 3 will only operate at the moment when the hermetic compressor provided with a pressure relieve system 8 operates. In other words, the operation state of the low-power transformer 3 is equal to the operation state of the hermetic compressor provided with a pressure relief system 8. In this way, the consumption of energy of the electric cooling system 1 will be lower than the consumption of energy of the electric cooling system known from the prior art and shown in figures 1A and 1 B.

The electric connection between the components that integrate the electric cooling system 1 is carried out by using conventional electric cables, the electric connection of the cooling equipment 7 to the network volt- age 2 takes place by means of the feed cable (power cord) itself of the cooling equipment 7. On the other hand, the electric connection between the low- power transformer 3, the cooling equipment 7 and the hermetic compressor provided with a pressure relief system 8 takes place by means of the primary electric terminal 5 and of the secondary electric terminal 6 of the transformer.

Figure 4 represents the electric cooling system 1 proposed in the present invention, considering the network voltage 2 with a value equal to 127VAC ±15% and the hermetic compressor provided with a pressure relief system specified with nominal operation voltage of 220VAC.

If the network voltage 2 is of 127VAC and the hermetic compressor provided with a pressure relief system 8 is specified for operation on 220VAC, one should only use a low-power voltage step up transformer 3, the electric connection scheme will be the same as shown in figure 3, that is, the cooling equipment 7 is connected to the network voltage 2 and the low-power transformer is electrically connected to the cooling equipment 7 and to the hermetic compressor provided with a pressure-relief system 8. Such a configuration is shown in figure 4.

It should be noted that in the electric cooling system 1 shown in figures 3 and 4, the electric loads 10 of the cooling equipment are electrically energized by the network voltage 2. Thus and as already mentioned, such electric loads (electronic boards, ventilators, illumination lamps and defrost heater element) should be specified for feed voltage of both 127VAC and 220 VAC.

An alternative connection to the electric cooling system 1 shown in figures 3 and 4 is shown in figure 5. As can be observed in this figures, determined electric loads 10 of the cooling equipment are electrically connected in parallel with to the hermetic compressor provided with a pressure relief system 8. In this way, the electric loads 10 are electrically energized by the secondary electric terminal 6 of the low-power transformer.

It should be noted that the electric loads 10 of the cooling equipment that enable this type of electric connection are the electric loads of low nominal power, such as ventilators, electronic board and illumination lamps.

Figure 6 and 7 represent an additional configuration of the electric cooling system 1 proposed in the present invention, but using a selection switch S1 at the entrance of the primary terminal 5 of the transformer 3. In this way and as can be better observed in figure 6, if the network voltage 2 is equal to 127VAC and the compressor 8 is projected for operation on 127VAC as well, it will not be necessary to use the transformer 3, and the selection switch S1 will be positioned so, as to deviate the electric current directly to the compressor 8.

If the network voltage 2 is equal to 220VAC and the hermetic compressor with a start pressure relief system 8 is projected for operation on 127VAC, the selection switch S1 will be commuted so as to direct the electric current to the primary terminal 5 of the transformer, resulting in a voltage on the secondary terminal 6 of the transformer equal to 127VAC, thus feeding the compressor 8 according to its nominal voltage. Such a configuration is better observed in figure 7.

It is important to point out that the commutation of the selection switch S1 may be made both manually by the user as automatically (elec- tronically) by the cooling system 1 itself, through an electronic control system that detects the amplitude of the feed voltage (network voltage 2). In this way, the cooling system 1 becomes a bivolt system.

In this way, one achieves an electric cooling system provided with an hermetic compressor with a start pressure relief system and a low- power transformer, the low-power transformer being electrically connected to the cooling equipment and to the hermetic compressor. The low-power transformer will operate only when the hermetic compressor provided with a pressure relief system is operating.

Claims

1. An electric cooling system (1) characterized by comprising at least:

- a low-power transformer (3) comprising a primary electric ter- minal (5) and a secondary electric terminal (6);

- a cooling equipment (7) fed by a network voltage (2); and

- a hermetic compressor provided with a pressure relief system

(8);

the electric cooling system (1) being configured so that: - the low-power transformer (3) is electrically connectable to the cooling equipment (7) and to the hermetic compressor provided with a pressure relief system (8), wherein:

the primary electric terminal (5) is electrically connectable to the cooling equipment (7) and the secondary electric terminal (6) is electrically connectable to the hermetic compressor provided with a pressure relief system (8).

2. The electric cooling system (1) according to claim 1 , characterized in that the network voltage (2) reaches values of 127VAC±15% OR 22vac±15%.

3. The electric cooling system (1) according to claim 1 , characterized in that the low-power transformer (3) and the hermetic compressor provided with a pressure relief system (8) are electrically fed by the cooling equipment (7).

4. The electric cooling system (1) according to claim 1 , character- ized in that the hermetic compressor provided with a pressure relief system

(8) comprises at least one method of relieving the starting pressure of the compressor.

5. The electric cooling system (1) according to claim 1 , characterized in that the hermetic compressor provided with a pressure relief system (8) is electrically connected to the low-pressure transformer (3).

6. The electric cooling system (1) according to claim 1 , characterized in that the cooling equipment (7) is provided with electric loads (10).

7. The electric cooling system (1) according to claim 6, characterized in that the electric loads (10) are electrically energized by the network voltage (2).

8. The electric cooling system (1) according to claim 6, character- ized in that the electric loads (10) are electrically energized by the secondary electric terminal (6) of the low-power transformer (3).

9. The electric cooling system (1) according to claim 6, characterized in that the electric loads (10) comprise the electronic control, the defrost heater element, ventilators, lamps, mechanical dampers and electric damp- ers.

10. The electric cooling system (1) according to claim 1 , characterized in that the low-power transformer (3) is a transformer of nominal electric power lower than or equal to 1000VA.

11. The electric cooling system (1) according to claim 1 , charac- terized in that the operation state of the low-power transformer (3) is equal to the operation state of the hermetic compressor of the pressure relief system (8).

12. The electric cooling system (1) according to claim 1 , characterized in that the electric connection between the cooling equipment (7) and the low-power transformer (3) is made by means of a selective switch (S1).

13. The electric cooling system (1) according to claim 12, characterized in that, according to the commutation of the selective switch (S1), the cooling equipment (7) is electrically connected to the primary terminal (5) or the cooling equipment (7) is electrically connected to the hermetic compres- sor provided with a pressure relief system (8).

14. The electric cooling system (1) according to claim 13, characterized in that the selective switch (S1) is commuted manually.

15. The electric cooling system (1) according to claim 13, characterized in that the selective switch (S1) is commuted electronically.