Refrigerating system with reduced noise emission

Abstract

The present invention relates to refrigerating system with reduced noise emission. The refrigerating system includes a fridge compartment for cooling items and comprising one or more sensors for controlling the temperature in the compartment. The refrigerating system further includes a machine room comprising fans, pipes for refrigerant, and a compressor, wherein the compressor is contained in a compressor module, and where the machine room comprises at least one temperature sensor connected to a processing unit adapted for processing temperature data using experimental data to determine the required fan speed for reducing thermal load and adjusting the fan speed. The invention also relates to method for controlling fan speed and reduce noise of one and more fans in a refrigerating system.

Description

Technical Field

[0001] The present invention relates to a refrigerating system equipped with a temperature sensor detecting the temperature inside a machine room and is configured to control the speed of a fan based on the temperature detected by the temperature sensor and reduce the noise emissions.Background

[0002] In households and commercial applications, refrigeration appliances are one of the main noise sources and can be a cause of annoyance due to their on / off operation. The EU has introduced a new energy label (EU) 2019 / 2019 where besides the mandatory declaration of sound power (Lw) for household appliances, the airborne acoustical noise is further split into emission classes. Therefore, the EU noise labelling directive offers a strong motivation to address appliance noise.

[0003] The noise source of the refrigerator is mainly the compressor, refrigerant flow and fan noise during operation. The noise evaluation of product problems in the product design stage is the sound power evaluation. However, although the product meets the noise nominal, noise problems may still occur. This is because the different proportions of noise at different frequencies will give people different hearing sensations. For example, high-frequency noise is sharp and harsh, and even if the value is not large, it will still annoy users.

[0004] As a household appliance that operates continuously for 24 hours, the noise performance index of a refrigerator is easily perceived by users.

[0005] As an essential household appliance, the refrigerator is in a state of constant power supply all year round. People expect the refrigerator to not only achieve the effect of preserving freshness and saving energy, but also reduce the noise generated during operation and provide users with a good rest environment.

[0006] The noise of refrigerators is relatively low most of the time, but when the compressor speed increases, the noise will increase significantly. To solve the difference in users' needs for refrigerator noise at different times, some refrigerators are equipped with infrared sensors or photoelectric sensors. The infrared sensors detect when people are approaching and operate with noise reduction. The photoelectric sensors determine whether it is day or night and operate in silent mode at night. There are also one-button silent air conditioners. A refrigerator collects the user's instructions to turn on the silent mode or return to the normal mode through the silent button, and reduce the speed of the variable frequency compressor, the speed-adjustable evaporator fan, and the speed-adjustable condenser fan in the silent mode. To achieve the purpose of effectively reducing the operating noise of the air-cooled refrigerator and providing users with a quiet resting space.

[0007] The above-mentioned existing noise reduction methods for controlling refrigerators cannot determine the silent operation period according to the user's daily routine, and through photoelectric sensors or one-button mute methods, the refrigerator will run silently for a long time, but cooling properties required according to ambient temperature will not be achieved. The evaporator fan and condenser fan run at low speed for a long time, which affects the cooling effect of the refrigerator and fails to achieve the intelligent noise reduction function.

[0008] Thus, there is a need for a refrigerating system in which the noise is reduced, while a sufficient cooling capacity is maintained.Disclosure of the Invention

[0009] An aspect of the invention is to provide a refrigerating system which can provide cooling with low noise emissions.

[0010] Another aspect of the invention is to provide a refrigerating system which automatically adjust cooling and noise emissions depending on ambient temperature.

[0011] In an aspect the present invention relates to a refrigerating system with reduced noise emission, where the refrigerating system includes a fridge compartment for cooling items and comprising one or more sensors for controlling the temperature in the compartment. The refrigerating system further includes a machine room comprising fans, pipes for refrigerant, and a compressor, wherein the compressor is contained in a compressor module comprising a box having walls covered with sound insulation material and fitted with noise filter at the inlet and at the outlet for noise mitigation. Moreover, the machine room comprises at least one temperature sensor connected to a processing unit adapted for processing temperature data using experimental data to determine the required fan speed for reducing thermal load and adjusting the fan speed.

[0012] The experimental data are stored in a memory, which may also referred to as an archive or LUT (look up table).

[0013] The fridge compartment according to the invention is adapted for cooling items such as food and beverage, and the refrigerating system is adapted for providing an optimized cooling with reduced noise due to use of a processing unit and experimental data. The reduction of noise is mainly obtained by controlling and optimizing the rotation speed of the fans. The experimental data is obtained by performing several experiments where temperature and associated fan speed are measured and recorded and the obtained data is stored in a memory or archive. The data may be stored as temperature curves with associated fan speed curves. Besides fan speeds and temperatures, the noise emission and energy consumption and compressor performance may be measured and recorded and stored in an memory such as a look up table (LUT). The data obtained by measuring the temperature, fan speed, noise emission and energy consumption in different situations can be used in an algorithm for calculating the optimal fan speed when the temperature has a certain value. When the refrigerating system operates in any ambient conditions from 10-43°C, the processing unit selects the predetermined fan curves from the LUT, which are optimised by balancing noise, temperature, performance and energy. The ambient temperature may also be measured and used in the algorithm for determining the fan curves.

[0014] In an embodiment at least one temperature sensor in the machine room is located next to the compressor in the compressor module and in close vicinity to the compressor. Close vicinity means that the temperature sensor is located in a distance from about 1 cm to about 15 cm from the outer surface of the compressor. Thus, it is possible for the temperature sensor to measure the temperature in the compressor module with high precision and thereby making it possible to adjust the fan speed to an optimized value, by using the temperature for processing by the algorithm and by using the data stored in the memory.

[0015] The refrigerating system according to the invention includes at least one evaporator fan and at least one machine room fan. The one or more evaporator fans ensure the cooling in the fridge compartment, and the at least one machine room fan ensures the cooling in the machine room. The evaporator fan and machine room fan are controlled by the processing unit which utilize input from the temperature sensors and data in an archive to adjust the speed of the fans.

[0016] To obtain maximum temperature control in the refrigerating system the one or more sensors in the fridge compartment are connected to the processing unit. The processing unit may process the input from the one or more sensors in the fridge compartment and adjust the speed of the fan or fans to obtain an optimized speed in respect of cooling and noise emission.

[0017] To obtain optimised sound reduction in the refrigerating system the sound insulation material in the machine room is selected from polyurethane foam, polypropylene foam, melamine foam, polyester, neoprene, cork, mineral fibre, fiberglass, or a combination of the materials which are all materials with excellent noise damping properties.

[0018] In an embodiment the fridge compartment comprises a temperature sensor in the upper part of the fridge compartment (i.e. the top part of the fridge compartment) and a temperature sensor in the lower part of the fridge compartment (i.e. the bottom part of the fridge compartment). By having a temperature sensor both in the upper part and in the lower part of the fridge compartment the temperature in the compartment is measured in different places apart from each other and thereby the cooling properties can be optimized by utilizing the different measurements and process the measurements in the processing unit.

[0019] In yet an aspect the present invention relates to a method for controlling fan speed of one and more fans in a refrigerating system including a fridge compartment for cooling items and comprising one or more sensors for controlling the temperature in the compartment, and further including a machine room comprising fans, pipes for refrigerant and a compressor module, said method comprising: measuring the temperature and fan speed in the machine room; transferring the measured temperature and fan speed to a processing unit for processing by an algorithm calculating an optimized fan speed using temperature and fan speed data from an archive; adjusting the fan speed in the machine room to a fan speed calculated by the algorithm as optimal in relation to the measured temperature in the machine room; wherein the temperatures and fan speed data in the archive are obtained from experimental data and stored in the archive for use in the algorithm for calculating fan speed in the machine room such that the fan speed is optimized to provide optimal cooling and noise reduction in the machine room at a specific temperature.

[0020] According to the method experimental data is used to determine the optimal fan speed in the refrigerating system, thus, the archive may comprise data about fan speed and temperature in the machine room and also data about fan speed and temperature in the fridge compartment. By use of the method it is possible to obtain reduced noise emission and optimizing the temperature, performance and energy. By using the method, the noise emission may be reduced with about 5 dBA, e.g. from 36,7 dBA to 31,8 dBA which is an improvement of 67 % in noise reduction.

[0021] In an embodiment of the method, the method also comprises the step of measuring the temperature and fan speed in the fridge compartment and transferring the measured temperature and fan speed to the processing unit for processing by the algorithm calculating an optimized fan speed using temperature and fan speed data from the archive. The method can also be used to control the temperature and fan speed in the fridge compartment and thereby, also control the noise emission from the fans in the fridge compartment.

[0022] According to an embodiment of the method the temperature is measured at two positions in the fridge compartment, preferably the temperature is measured in an upper position and in a lower position, i.e. the temperature is preferably measured in the upper part of the fridge compartment and at the bottom of the fridge compartment. Thereby it is possible to register it there is differences in the temperature and to obtain a well-controlled temperature level in the fridge compartment.

[0023] The method is able to detect by the input from the temperature sensors if the temperature in the refrigerating system becomes critical, e.g. the temperature rises to too high a temperature. In such a situation the processing unit based on a threshold temperature from the archive determines if the measured temperature in the machine room is critical and if increased cooling is required. If the temperature is critical the processing unit initiates cooling by increasing the fan speed.

[0024] In embodiments of the method when increased cooling is required the increased cooling is obtained be increasing the fan speed. Thus, the method may control the temperature in the refrigerating system by controlling the fan speed, and by controlling the fan speed the method can also control the noise emission from the fans, and thereby obtaining optimised cooling with lowest possible noise emission from the fans.

[0025] The experimental data which are utilized in the method and for calculations by the algorithm includes data about temperature and fan speed and may also include data about energy consumption and performance. Moreover, the data may include information about ambient temperature.

[0026] As mentioned the experimental data includes data about the fan speeds and related temperatures in the system, and these data are processed by the algorithm to obtain an optimized relation between fan speeds, temperature and noise emission. The fan speeds serve to adjust the temperature in the refrigerating system as the flow of cooled air in the system is determined by the fan speeds circulating the cooled air in the system. As a general rule the majority of noise emission depends partly on the fan speeds and partly on the operation of the compressor, and according to the invention the noise emission from the fans are optimised, i.e. optimized to be as low as possible, by using the experimental data and temperature measurements which are processed in the processing unit by the algorithm. The algorithm compares the measured temperature with fan speeds and related temperatures in the archive and select the fan curve with optimized properties in relation to the measured temperature, thereby ensuring optimized cooling with the lowest possible noise emission from the fans. The noise emission from the compressor is controlled by the compressor module with the noise insulation.Detailed description of the InventionBrief Description of the Drawing(s)

[0027] The invention will be explained with reference to a drawing in which Fig. 1 shows a refrigerating system according to the invention; Fig. 2 shows the principles of the invention in a diagram; Fig. 3 shows details of the compressor module.

[0028] Figure 1 is view on a refrigerating system according to the invention with a refrigerator 1 seen from the front A and from the back B.

[0029] The refrigerator 1 has a fridge compartment 2 with shelves 3 for storing the items to be cooled. The fridge compartment 2 includes variable speed evaporator fans 4 located in the upper part of the fridge compartment 2. The evaporator fans 4 are controlled by using real time measurements of temperature in the machine room, in particular the compressor module 20. The evaporator fan's 4 speed is independent of the compressor speed, set-point and the internal temperature sensing provided by the upper temperature sensor 5 and the bottom temperature sensor 6. This constillation will minimise noise emissions during long cooling periods or other scenarios.

[0030] The principles of the invention is outlined in the basic block diagram presented in fig. 2. The controller 11 recieves input from the temperature sensor A 12 (corresponding to temperature sensor 5 in the fridge compartment in fig. 1), temperature sensor B 13 (corresponding to temperature sensor 6 in the fridge compartnent in fig. 1), and the machine room temperature sensor 14 (corresponding to the temperature sensor 27 in fig. 3). When the user activates the unit and selects a set-point temperature from the user interface 10, the controller 11 evaluates the temperature inside the machine room. Based on that input the controller 11 uses an algorithm for calculations based on predifidefined fan curves stored in a memory or archive comprising data for the evaporator and machine room fans. In case the ambient conditions change, the controller 11 will receive input from the sensors 12, 13 and 14, and adjust the fans speed according to fan curves in the LUT (look up tables). The fan curves are optimised by balancing noise, temperature perfomance and energy to obtain the best possible performance and will depend on each particular appliance. Furthermore, safety features relating to the compressor 15 including information about compressor temperature overload are also stored in the memory or archive, so if a temperature threshold is reached the controller 11 will try to cool the machine room by increasing progressively the fan speed including the speed of the compressor module fan 17.

[0031] The controller 11 may also receive information and data about other features, such as energy consumption and ambient conditions, such as ambient temperature.

[0032] Fig. 3 illustrates the compressor module 20 where fresh airflow intake is brought into the module through inlet filter 21, which also acts as a discontinuity in the noise path. The module 20 is made out of steel sheets 22 folded in a L-shaped design and fixed to the compressor rail 23 by bolts. The modular design allows for easy parts replacement or service. Sheets of 10 mm thickenss of melamine foam 24 are placed to cover the inside walls of the module. The melamine foam will serve to minimize sound refections and reduce noise. As the fresh air passes thorugh the module, the temperature of the air will increase due to the heat transfer from the compressor 25. The compressor 25 is fitted on the top with a tray 26 for excess defrost water. Moreover, the change in the air temperature is continuosly monitored by the temperature sensor 27 placed in close proximity to the compressor 25.

[0033] The airflow exits the module 20 through the outlet filter 28 - which also acts as a barrier in the noise path - and the airflow continues via the variable speed fan 29 that dictates the airflow rate of the module. Finally, silencer 30 is installed at the fan outlet in order to reduce air turbulence and noise.List of reference numbers:

[0034] 1fridge 2fridge compartment 3shelves 4evaporator fans 5upper temperature sensor 6lower temperature sensor 10user interface 11controller 12temperature sensor 13temperature sensor 14temperature sensor 15compressor 16evaporator fans 17compressor module fan 20compressor module 21inlet filter 22steel sheets 23compressor rail 24melamine foam 25compressor 26tray 27temperature sensor 28outlet filter 29fan 30silenser

Claims

1. A refrigerating system with reduced noise emission, said refrigerating system including a fridge compartment for cooling items and comprising one or more sensors for controlling the temperature in the fridge compartment, said refrigerating system further including a machine room comprising fans, pipes for refrigerant, and a compressor, wherein the compressor is contained in a compressor module comprising a box having walls covered with sound insulation material and fitted with noise filter at the inlet and at the outlet for noise mitigation, and wherein the machine room comprises at least one temperature sensor connected to a processing unit adapted for processing temperature data using experimental data to determine the required fan speed for reducing thermal load and adjusting the fan speed.

2. A refrigerating system according to claim 1, wherein at least one temperature sensor in the machine room is located next to the compressor and in close vicinity to the compressor.

3. A refrigerating system according to claim 1 or 2, wherein the one or more sensors in the fridge compartment are connected to the processing unit.

4. A refrigerating system according to any one of the claims 1-3, wherein the system includes at least one evaporator fan and at least one machine room fan5. A refrigerating system according to any one of the claims 1-4, wherein the sound insulation material is selected from polyurethane foam, polypropylene foam, melamine foam, polyester, neoprene, cork, mineral fiber, fiberglass or combinations of the materials.

6. A refrigerating system according to any one of the claims 1-5, wherein the fridge compartment comprises a temperature sensor in the upper part of the fridge compartment and a temperature sensor in the lower part of the fridge compartment.

7. A method for controlling fan speed (and reducing noise) of one and more fans in a refrigerating system including a fridge compartment for cooling items and comprising one or more sensors for controlling the temperature in the compartment, and further including a machine room comprising fans, pipes for refrigerant and a compressor module, said method comprising: - measuring the temperature and fan speed in the machine room; - transferring the measured temperature and fan speed to a processing unit for processing by an algorithm calculating an optimized fan speed using temperature and fan speed data from an archive; - adjusting the fan speed in the machine room to a fan speed calculated by the algorithm as optimal in relation to the measured temperature in the machine room; wherein the temperatures and fan speed data in the archive are obtained from experimental data and stored in the archive for use in the algorithm for calculating fan speed in the machine room such that the fan speed is optimized to provide optimal cooling and noise reduction in the machine room at a specific temperature.

8. A method according to claim 7, wherein the method comprises the step of measuring the temperature and fan speed in the fridge compartment and transferring the measured temperature and fan speed to the processing unit for processing by the algorithm calculating an optimized fan speed using temperature and fan speed data from the archive9. A method according to claim 7 or 8, wherein the temperature is measured at two positions in the fridge compartment, preferably the temperature is measured in an upper position and in a lower position.

10. A method according to claim 7, 8 or 9, wherein the processing unit based on a threshold temperature from the archive determines if the measured temperature in the machine room is critical and if increased cooling is required.

11. A method according to any one of the claims 7 to 10, wherein the increased cooling is obtained be increasing the fan speed.

12. A method according to any one of the claims 7 to 11, wherein the method comprises the step of measuring the ambient temperature and transferring the measured temperature to the processing unit for processing by the algorithm calculating optimized fan speeds using temperature and fan speed data from the archive.

13. A method according to any one of the claims 7 to 12, wherein the method comprises the step of measuring the energy consumption and transferring the measured data to the processing unit for processing by the algorithm for calculating optimized fan speeds.

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