SYSTEM AND METHOD OF DIAGNOSIS THROUGH DETECTION OF MECHANICAL WAVES IN REFRIGERATION SYSTEMS AND/OR HOUSEHOLD APPLIANCES

Abstract

The present invention relates to a system and a method of diagnosis for a refrigeration system and/or household appliance which, based on a multiplicity of physical magnitudes detected, determine and inform the operating condition of said refrigeration system and/or of its components. Basically, the magnitudes are divided into two groups, namely: (i) those from which spectral signatures will be generated (magnitudes relating to mechanical vibrations); and (ii) magnitudes from which spectral signatures will not be generated. The spectral signatures are compared with the standard signatures, and the diagnosis is provided Digital based on this comparison. After the operating condition has been diagnosed, it is stored in a database, and a processing record of the system operation is updated. The operating central conditions are made available for viewing, and based on the record viewed, it is possible to determine whether or not the refrigeration system and/or household appliance and the components thereof are malfunctioning or not. The application further describes a compressor whose diagnosis can be determined by the method and system of diagnosis according to the present invention.

Description

This application claims priority of Brazilian patent case No. P10702369-3 filed on May 29, 2007, the disclosure thereof being hereby incorporated by reference.

The present invention relates to a system and a method of diagnosis that enable the operating conditions of household appliances, refrigeration systems and/or components thereof to be made available to be viewed immediately or later. The present invention further relates to a compressor diagnosed by the system and method of diagnosis of the present invention.

DESCRIPTION OF THE PRIOR ART

Refrigeration systems, in general, are widely known by most people. Thus, since these systems are, in many cases, considered to be a human need, it is interesting to develop methods that are able to manipulate, control or diagnose their operation. However, before mentioning some types of methods for controlling refrigeration systems, a typical prior-art example of a refrigeration system and of the application thereof should be described.

Typically, a refrigeration system comprises a circuit, wherein a cooling fluid travels through several components, during which travel the volume of the fluid is expanded and compressed, and its temperature and pressure rise and fall. It is important to observe the close relationship between the aforementioned magnitudes when dealing with fluids.

The components which form an ordinary refrigeration system are, for example: compressor, evaporator, condenser and capillary tube. The compressor, as the name itself indicates, compresses the cooling fluid, increasing its pressure and consequently its temperature, so that the fluid is pumped and forced to flow through the cooling circuit.

After leaving the compressor, the cooling fluid circulates through the condenser, which is responsible for decreasing the fluid temperature without decreasing its pressure. This condenser is usually a long duct arranged in such a way as to have rectilinear parallel parts connected to one another, at their ends, by sinuous or curved parts, substantially shaped like an “S”. Thus, because this condenser is in contact with the environment, the cooling fluid loses heat to the environment as it circulates inside the condenser, thus having its temperature decreased.

From the condenser, the cooling fluid moves to the capillary tube, also known as expansion valve, whose function is to create resistance to the passage of the fluid, thus causing a large pressure difference between the fluid in the condenser and the fluid in the next component: the evaporator, where the pressure is low. Thus, due to the difference between the low pressure in the evaporator and the high pressure and fluid resistance in the capillary tube, the cooling fluid undergoes an abrupt transition when it moves towards the evaporator, having its volume suddenly expanded and being inserted into a low pressure environment. Therefore, considering the close relationship between the temperature, pressure and volume magnitudes, it can be concluded that: if the volume increases and the pressure decreases, and the temperature of the cooling fluid also decreases, which contributes to the absorption of the environment heat in contact with said evaporator.

Finally, the cooling fluid, in this condition of expanded volume, low pressure and low temperature, moves from the evaporator to the compressor, where its volume is then reduced and its pressure and temperature are increased, restarting the refrigeration cycle.

The typical system exemplified above can be applied in household refrigerators, air conditioners, commercial refrigerators, product display refrigerators and any other device that needs to be refrigerated or to have refrigeration.

Now that a refrigeration system has been described, we get back to the question of how its operation can be controlled, diagnosed or manipulated. In this regard, it should be pointed out that the prior art does anticipate a system and method to control the temperature in refrigeration and heating systems, however, it does not provide a method or system to diagnose malfunction and thus prevent major failures which can occur in this system.

Therefore, with respect to the diagnosis of a refrigeration system, it is fair to say that for said system to work properly, different robustness characteristics are required from the refrigeration system and from its components (fan, thaw resistance, shutdown valve, compressor etc.). However, these characteristics may vary depending on the environment where the refrigeration system is, considering that each environment has specific characteristics, which can vary with time, such as, for example: humidity, dust and ventilation. Moreover, other factors can alter the robustness properties of the components, among which the condition of use, wear and aging of the components. That is, along their useful life, the components, as any physical device, are subjected to wear and alterations in their working capacity due to the conditions of the environment or of use.

Thus, the conditions of use, wear and aging of the components can cause failures in these devices, which will reflect on the efficacy of the refrigeration system. These failures can be classified into two groups: (i) full collapse; and (ii) slight deviation.

In the full collapse situation, the defective element of the system can exhibit irregular or intermittent operation or can be completely inactive, jeopardizing the whole refrigeration cycle. Thus, a failure of this magnitude can bring huge losses, firstly because the elements of a typical refrigeration circuit are arranged in series, that is, one defective device can paralyze the activities of the system.

Secondly, the losses resulting from this type of failure occur, in some cases, due to the slow process of identification of the malfunction, since the system has very large time constants and the user can only notice a deviation in the refrigeration cycle after a long time has passed. In this scenario, when the defect is not detected, even if the system is still working, it will not operate correctly and will overload the components, substantially reducing their useful life. In many cases, the loss caused by the damage to the refrigerated load can exceed the cost of maintenance of the refrigeration system.

On the other hand, in the situation where there is a slight deviation in the operation the process to identify the defective element is even slower and more difficult, since the malfunction is easily mistaken for variations that the system can present due to changes in the temperature of the environment and/or in the thermal load. Thus, when a failure of this type is finally identified, the time during which the system was malfunctioning, unfortunately, may have been enough to jeopardize one or more components or even the refrigerated load. In addition to this complication, in most cases, the process for identifying the defect is performed empirically and based on the previous experience of the person in charge of the maintenance.

Additionally, some refrigeration system failures are caused by improper handling by the user and by the little attention given to the identification of the use by the people around or even interacting with the refrigeration system in an improper manner.

Nonetheless, when the concept of refrigeration system is extrapolated for the purpose of making diagnoses and household appliances in general are considered, the same types of failures and difficulties regarding their identification occur.

In this context, up to this moment, the prior art has not disclosed any system or method of diagnosis that is able to detect failures in components of a refrigeration system or in household appliances in general by using means that detect both magnitudes internal to the refrigeration system or household appliance and magnitudes representing characteristics of the environment or of the load to be refrigerated, in the case of a refrigeration system, alerting the user to the need for preventive maintenance, minimizing the downtime of the equipment.

Due to this gap in the prior art, there is nowadays no compressor, or another rotating element, of a refrigeration system being diagnosed by a system or method of diagnosis which is able to detect failures and which use means to detects magnitudes that are inside and outside the compressor, alerting the user to the need for preventive maintenance.

OBJECTS OF THE INVENTION

Therefore, the first objective of the present invention is to provide a method of diagnosis that is able to define the steps required to perform the diagnosis of the working condition of a refrigeration system or a household appliance.

The second objective of the present invention is to provide a diagnosis system for refrigeration systems or household appliances that is able to detect specific malfunctions relating to each component to be monitored. Finally, the third objective of the present invention is to provide a refrigeration system compressor whose diagnosis is defined by the system and/or method of diagnosis cited in the previous paragraphs.

BRIEF DESCRIPTION OF THE INVENTION

The first objective of the present invention is achieved by means of a method of diagnosis for refrigeration systems or household appliances, comprising the steps of:

(i) Detecting signals, wherein vibrating mechanical wave signals or sound pressure signals from the refrigeration system and the environment near the system or the appliance are detected;

(ii) Generating a spectral signature of the vibration parameters detected in step (i);

(iii) Assessing the operating condition of the components of the refrigeration system or household appliance: wherein the spectral signatures generated in step (ii) are compared with the spectral signatures relating to normal operating conditions of the refrigeration system or household appliance;

(iv) Updating the records: the operating condition of the components of the refrigeration system or household appliance assessed in step (iii) is registered in a database; and

(v) Operating condition alert/signaling: wherein the operating condition assessed in step (iii) is made available for viewing.

The second objective of this invention is achieved by means of a diagnosis system for a refrigeration system or household appliances in general, comprising at least:

• • a transducer that is able to detect mechanical vibrations or sound pressure waves of the components of the refrigeration system as a whole and its surroundings or of the household appliance and its surroundings; and
  • a digital processing unit that receives the parameters obtained by the transducer and is able to identify spectral patterns from the signals received from the transducer.

The diagnosis system determines the operating condition by comparing the spectral patterns identified with spectral patterns previously stored in a memory unit.

The third objective of the invention is achieved by means of a refrigeration system compressor whose diagnosis is made using the system and/or method of diagnosis of the first and second aims.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be described below in more detail, based on an example of execution represented in the drawings. The figures show:

FIG. 1—a schematic view of the diagnosis system according to the present invention, including the preferred embodiment with the alternative embodiment; and

FIG. 2—a flowchart of the method of diagnosis according to the present invention.

DETAILED DESCRIPTION OF DRAWINGS

Firstly, before starting the description of the system and of the method themselves, the various concepts and particularities involved in the subject matter of the present invention should be described, divided into topics as follows.

The Refrigeration System and Household Appliance

The refrigeration system whose operating conditions are to be diagnosed by the method and system of the present invention can be used for different refrigeration purposes, such as: commercial refrigerators, household refrigerators, freezers, air conditioners etc. The method and system of the present invention can also be used in possibilities other than the ones exemplified.

Preferably and conceptually, the refrigeration system to be diagnosed is defined as a system comprising the basic refrigeration elements, namely: compressor, condenser, expansion device and evaporator, and whose operation occurs as provided in the prior art.

Moreover, the present invention also contemplates in its system and method of diagnosis the possibility of diagnosing the operating conditions of a household appliance, not only of a refrigeration system. The household appliance may be any appliance known in the prior art that can be diagnosed by the method and/or system of diagnosis of the present invention.

Magnitudes and Transducers

For the system and method of diagnosis of the present invention to operate, several magnitudes need to be measured.

Thus, among the several physical magnitudes involved in a refrigeration system or in a household appliance, the ones that will preferably be used in the system and method of the present invention can be divided into two groups, namely:

(i) Mechanical wave signals or sound pressure waves of the components of the refrigeration system or of the refrigeration system as a whole and/or of the household appliance and of the surroundings of the refrigeration system and/or household appliance; and

(ii) parameters of the refrigeration system and of an environment to be refrigerated, or parameters of the household appliance.

As will be shown below, the first group is more important in determining the operating condition of the system, while the second group is used to reinforce or confirm the analysis made based on the first group.

More specifically, the magnitudes of group (i) are mechanical vibrations of the components of the refrigeration system and/or of the household appliance, which vibrations are caused by the fact that the components are associated with at least one compressor or another rotating element which may integrate the refrigeration system. This group further comprises the noise generated by the movement of people in the surroundings of the refrigeration system and/or of the household appliance.

The magnitudes of group (ii) are preferably, though not limited to, the following: external temperature; temperature of the environment to be refrigerated, in the case of the refrigeration system; voltage and electric current of the components of the refrigeration system and/or of the household appliance.

Thus, in view of the need to measure the aforementioned magnitudes, a plurality of transducers is required to detect all these parameters, so that, based on the data collected, the system and method of the present invention can diagnose the refrigeration system.

Therefore, at least one transducer 2, or a plurality of transducers 2, is responsible for detecting the magnitudes of group (i), that is, it is responsible for detecting the mechanical wave signals, which can also be referred to as mechanical vibrations or sound pressure waves of the components of the refrigeration system, of the refrigeration system as a whole and/or of the household appliance, preferably comprising: accelerometers, microphones or audio sensors that are able to detect the aforementioned mechanical vibrations or sound pressure waves of the components or, even, the noise generated by the people circulating or present in the surroundings of the refrigeration system and/or of the household appliance. However, any combination of the cited preferred examples can be used, that is, accelerometers, microphones or audio sensors can be used by themselves, or an accelerometer can be used with one or more microphones, or a microphone can be used with one or more audio sensors, and so on. Thus, it is obvious that the combination of these transducers is not a limiting factor to the scope of the present invention.

A second plurality of transducers 3, which is responsible for detecting the magnitudes of group (ii), preferably comprises: at least one temperature sensor to measure the internal temperature of the refrigeration system and, if applicable, of the household appliance; at least one temperature sensor to measure the temperature external to the refrigeration system and/or to the household appliance; and voltage and electric current sensors.

Preferably, the first plurality of transducers 2 comprises at least one microphone to detect the movement of people in the surroundings of the refrigeration system and/or of the household appliance and microphones to detect the mechanical vibrations or pressure waves of the refrigeration system and/or household appliance.

These transducers 2,3, the first plurality and the second plurality, can be placed in different positions of the refrigeration system and/or of the household appliance, depending on the magnitude to be detected. In this regard, for the first plurality of transducers 2, the microphone to detect the presence of people in the surroundings of the refrigeration system and/or household appliance, for example, should be put in a place where it can detect the noisy sound signals that indicate the presence and the circulation of people nearby. Taking as an example a refrigeration system associated with a commercial refrigerator (commonly used in supermarkets and also used to display products), the microphone in question can be placed in the front portion of the refrigerator, since this is the closest possible position to the people.

The external temperature sensors, in general, are preferably placed in the external portion of the refrigeration system, whereas the internal temperature sensor is placed in a position where it can detect the temperature in the region of the load to be refrigerated, in the case of a refrigeration system. Moreover, regarding the second plurality of transducers 3, the voltage and electric current sensors should be placed near the components from which a complement or confirmation to the diagnosis can be generated, as will be explained below.

Spectral Signature

The system and method of diagnosis of the present invention uses the spectral signatures so that the operating condition of the refrigeration system can be determined and the user or the person in charge of the maintenance can be alerted.

The spectral signature can be defined as a translation of the behavior of a component on the temporal basis into a magnitude in the frequency domain, in other words, the spectral signature is equivalent to the frequency spectrum of a vibrating element (motor, compressor, etc.). In the case of the present invention, the spectral signatures are preferably generated by the first plurality of transducers 2, the one intended to detect the mechanical vibration or the sound pressure waves of the refrigeration system and/or of the household appliance, and also to detect the noise surroundings of the refrigeration system and/or household appliance, that is, they are generated from mechanical wave signals (vibration and sound). Thus, first the magnitudes in question are detected by their respective transducers, and then, after the application of a specific algorithm, the frequency spectra, that is, the spectral signatures, are generated. Preferably, this specific algorithm is of the Fast Fourier Transform (FFT) type.

Thus, considering that a component of the refrigeration system, in a normal operating condition, vibrates in certain frequencies and has certain amplitudes (both identified through its spectral signature), even the smallest variation in the operation will alter its usual frequencies and amplitudes, and it will start to oscillate in other in other frequencies with other amplitudes, that is, in an abnormal operating condition.

This can be observed if we take as an example a motor or even a compressor. In this situation, when the compressor vibrates in a normal operating condition, it produces an audible noise at specific frequencies and amplitudes, however, the sound of this noise is altered when the motor is, for example, malfunctioning. In other words, if the sound consists of a series of frequencies and amplitudes relating to said frequencies, the altered sound of this malfunctioning motor indicates, automatically, a change in its normal operating condition, since the oscillation frequencies and the related amplitudes have been altered.

Based on this reasoning, an alteration in the operating condition can be detected by comparing the spectral signature obtained in a normal operating condition with the one generated from recently detected vibrations. Thus, the operating condition of the system and/or household appliance as a whole or of the components thereof associated with the first plurality of transducers 2 is duly monitored.

Similarly, in the case of detection of people in the surroundings of the refrigeration system and/or of the household appliance, the noise detected is transformed into the frequency domain, so that a pattern of frequencies of noises relating to the amount of people is generated, and when this pattern is altered, a clear reading of a change in behavior can be obtained by comparing the spectral signature of the standard condition with the one recently generated from the mechanical vibrations of the sound detected.

Operation Patterns

For the diagnosis of the system to be confirmed, as aforementioned, the standard spectral signature of the system needs to be compared with the spectral signature generated from the current operating conditions. For this purpose, the method and system of the present invention relies on standard spectral signatures stored in a database. It should be further pointed out that the system and method of the present invention can use spectral signature ranges or intervals associated to an operating condition to make diagnoses. In this case, the comparison would be made between the signature generated and the range of signatures stored in the database. Moreover, there is the possibility that the aforementioned database has a series of standard values for the parameters that will not generate spectral signatures, namely: current, voltage and temperature, that is, non-vibrating signals. Thus, a comparison between, for example, a standard voltage and a read voltage can be made to complement or confirm the result of the diagnosis already obtained by comparing spectral signatures. The system and method of the present invention also contemplates the possibility of storing operation patterns for more than one vibration mode. Conceptually, a vibration mode is the level at which the system and/or its components vibrate, that is, a level at which the components are set to oscillate. For example, a compressor set to work at zero or 3600 rpm comprises two vibration modes, namely: 0 and 3600 rpm. On the other hand, a variable speed compressor can comprise a variety of vibration modes, due to the variability of its rotation.

Thus, the database stores spectral signatures and operating condition patterns corresponding to each vibration mode that the components or the system has, that is, each mode of operation generates a specific spectral signature for a given related operating condition.

In this case, the comparison will be made only between the signatures defined or related to the same vibration mode, that is, if the signature generated was based in a reading of a vibration at 3600 rpm, it will be compared with the standard spectral signature of the operating condition for the same rotation.

Preferably, the components of the refrigeration system have at least two modes of operation, and, if applicable, may have more than two, as is the case with a variable speed compressor.

Record of Use

As the system and method of diagnosis detect the parameters and vibrations obtained through the first and second pluralities of transducers, the data relating to these consecutive readings are stored in the aforementioned database. These data include the date and time of the reading, the component that is being checked and the respective operating condition thereof, so that a record of use is created.

This record of use contains the data of each measurement, so that it is possible to keep track of the operating condition of the system and/or household appliance and of their components over time. Thus, in case the refrigeration system and/or household appliance is suffering a malfunction of the slight deviation type, said malfunction will be easily detected, since the user or the person in charge of maintenance will be constantly notified that the system is presenting slight variations in its operating behavior, thus excluding the possibility of mistaking a slight deviation for a minor variation in the operating conditions due to changes in the environment.

This confusion is cleared, in fact, when the record of use is analyzed, since the behavior of the physical magnitudes of the refrigerating system and/or household appliance tend to adapt to the variations in the environment (for example, to the temperature variations) and go back into balance after a short period of time, whereas in the situation of malfunction of failure, they tend to remain at an operating condition other than the normal one for a longer period of time.

Alert and Signaling

After the spectral signatures (and, if applicable, the other magnitudes which do not generate spectral signatures) have been compared, the system and method of the present invention need to be able to alert the user or the person in charge of maintenance to possible failures. Thus, the system and method of the present invention have an alert interface 6 which, as the name indicates, gives the user early warnings about deviations from the normal operating conditions of the system.

Preferably, this alert interface 6 comprises at least one display and/or terminals for a portable reading device to be connected, thus making the operating condition available for viewing.

Therefore, with the system and method of the present invention periodically diagnosing the operating conditions of the refrigeration system and/or household appliance and informing the user of these conditions, damages to their respective components can easily be prevented.

Diagnosis System

Now that the components and some particularities of the diagnosis system have been described, the interaction between the elements that form said system should also be described. Thus, as can be seen from FIG. 1, the diagnosis system 1 of the present invention comprises: a first plurality of transducers 2, a second plurality of transducers 3, a digital processing unit 4, at least one memory unit 5 and an alert interface 6. It should be pointed out that FIG. 1 illustrates the preferred embodiment of the diagnosis system of the present invention in combination with an alternative embodiment, considering that the second plurality of transducers 3 is optional for the realization of the present invention.

As aforementioned, the first plurality of transducers 2 detects the magnitudes relating to the mechanical vibrations both inside and outside the refrigeration system, collecting parameters regarding the movement of people and the oscillations of the refrigeration system.

In an alternative embodiment of this diagnosis system, the second plurality of transducers 3 detects the magnitudes that will support and complement the diagnostic conclusions reached based on the mechanical vibrations.

The magnitudes detected by the first and second plurality of transducers 2, 3 will be transmitted to the digital processing unit 4, which will be responsible for transforming the information read into a parameter to obtain the diagnosis. The association between the transducers and said digital processing unit 4 can be made by means of wires and cables or, if the designers and people skilled in the art prefer, by wireless technology, and it is important to point out that the data transmission means is not a limiting factor to the scope of the present invention, and therefore other means, forms and methods can be applied.

A memory unit 5, which stores in this database the standard spectral signatures and predefined parameter values of the refrigeration system and/or household appliance, in addition to the record of use (record of data obtained from the first and second pluralities of sensors), is associated with the digital processing unit 4. This memory unit 5 is preferably of the non-volatile type, such as, for example: EPROM, EEPROM, FLASH, among others.

Thus, for the diagnosis of the refrigeration system to be made, the digital processing unit 4 is set to generate the spectral signatures of the parameters obtained from the first plurality of transducers 2, that is, to identify spectral parameters from the signals received from at least one transducer, to compare the signatures generated with the standard spectral signatures and enter the record of use in the memory unit 5 database.

From the comparison between the recently generated spectral signatures and those corresponding the normal operating conditions stored in the database, it can be instantly detected whether the refrigeration system has failures of the full collapse type if, for example, a component is completely inactive.

On the other hand, in case a component of the refrigeration system exhibits an intermittent operation behavior, when the record of use is made available for viewing, it will indicate the malfunction, since the inconstancy of the activity of the system or of one or more components over time will have been identified. The same reasoning applies to slight deviations in the operating condition, as already discussed.

In an alternative embodiment, in addition to the diagnosis made by comparing spectral signatures, the diagnosis system of the present invention contemplates the possibility that other magnitudes may aid in ascertaining the operating condition, and said aid works as complementary information for confirmation purposes. For example, in case a component is found to be in a condition of complete inactivity, the current, the voltage, the temperature or other magnitudes which do not generate spectral signatures can be used to verify and confirm whether the component is indeed in inactive. In fact, the magnitudes that are read but do not generate spectral signatures are interpreted, or not, based on predetermined values stored in the memory unit 5.

It should be further noted that this digital processing unit 4 is associated with the alert interface 6, so that the data relating to the operating conditions of the refrigeration system will be made available for viewing through said interface 6 as soon as they have been obtained.

Method of Diagnosis

More specifically, the diagnosis system of the present invention provides the user with information regarding the refrigeration system and/or household appliance by means of a method of diagnosis which, through its steps, discriminates the actions performed by the diagnosis system.

Step (i)—Signal Detection

According to this method, a flowchart of which is illustrated in FIG. 2, the first step is signal detection, which comprises the detection of mechanical wave signals, vibrating signals or sound pressure signals from the refrigeration system and/or household appliance. In an alternative embodiment, this step may comprise the detection of non-vibrating signals relating to parameters of the system and/or household appliance.

Physically, said mechanical wave signals correspond to the mechanical waves which propagate through air or through the structure of the refrigeration system and/or household appliance, that is, they comprise signals relating to the noise generated by the people in the surroundings of the refrigeration system and signals relating to the mechanical vibration of the system and its components. The non-vibrating signals, in turn, correspond to parameters which do not relate to mechanical oscillations measured to obtain the diagnosis of the refrigeration system, such as temperature, voltage and electric current, referring to the system as a whole or to one or more of its components.

Relationship Between Step (i) and the Diagnosis System

The signal detection step is carried out by the first and second pluralities of transducers 2, 3. The mechanical wave signals are detected by the first plurality of transducers 2 and the non-vibrating signals are detected by the second plurality of transducers 3. Right after the detection, these signals are transmitted, as aforementioned, to the digital processing unit 4.

Step (ii)—Spectral Signature Generation

After the data detection, the method of diagnosis according to the present invention comprises the step of generating a spectral signature of the mechanical wave signals. In this step, similarly to what happens in the diagnosis system, the signals detected are transformed into the frequency domain for their spectral signatures to be then generated.

Relationship Between Step (ii) and the Diagnosis System

The spectral signatures of the second step of this method are generated in the digital processing unit 4 of the diagnosis system by an algorithm of the Fast Fourier Transform (FFT) type.

Step (iii)—Operating Condition Assessment

Once the spectral signatures of the mechanical wave signals detected have been obtained, the method makes an assessment of the operating condition of the components of the refrigeration system and/or household appliances, that is, the spectral signatures generated in step (ii) are compared with the standard spectral signatures relating to the normal operating conditions of the refrigeration system and/or household appliance. This information would be enough to determine whether or not the system is operating normally. However, in order to increase the reliability of the diagnosis provided by the method of the present invention, this step (ii) further comprises an interpretation of the values presented by the non-vibrating signals. Thus, the conclusions regarding the vibrating signals will be validated, reinforcing and ensuring the reliability of the diagnosis provided.

Similarly to what happens in the diagnosis system, this interpretation can be made based on predetermined values, through comparisons, or not.

In case the system has different vibration modes, the spectral signature generated will be compared with the standard spectral signature relating to the mode of vibration detected, thus ensuring that the diagnosis is obtained for the same vibration mode.

Relationship Between Step (iii) and the Diagnosis System

The assessment of the operating condition is made in the digital processing unit 4 by comparing the spectral signatures generated with the ones relating to normal operating conditions previously stored in the unit memory 5 database. Moreover, the digital processing unit 4 further verifies the cohesion of the parameters relating to the non-vibrating signals, interpreting them based on predefined values or on previously established settings. Thus, the diagnosis generated by the spectral signatures is confirmed by the non-vibrating magnitudes.

Step (iv)—Record Update

Once the operating condition of the components, and consequently of the system as a whole and/or of the household appliance, has been identified and confirmed, the method moves on to step (iv), which comprises updating the record of use, that is, the operating condition of the components of the refrigeration system assessed in step (iii) and the values of the non-vibrating signals obtained in step (i) are registered in a database.

Thus, with the creation of the record of use, it is possible to keep track of the variation of the operating condition of the refrigeration system and/or household appliance over time. Therefore, if the frequencies and amplitudes of a component remain altered for period of time exceeding the time required for them to adapt to the variations in the environment, it can be concluded or verified that there is a failure in the system.

Relationship Between Step (iv) and the Diagnosis System

The record generated in step (iv) by the digital processing unit 4 is stored in the memory unit 5 database.

Step (v)—Operating Condition Alert/Signaling:

Once the record has been updated, the user or person in charge of maintenance needs to be informed of the operating condition so that, in case any abnormality is occurring, the proper measures can be taken to solve the problem. Thus, the operating condition obtained in step (iii) is made available for viewing.

Relationship Between Step (v) and the Diagnosis System

The operating condition alert and signaling procedure of the diagnosis system is performed by the alert interface 6, which, as aforementioned, can be a display or terminals to which a portable reading device will be connected.

Compressor

In addition to the system and method of diagnosis, the present invention further relates to a compressor which acts as a component of a refrigeration system and whose diagnosis is determined by the system and method of diagnosis according to the present invention.

This compressor can be any conventional compressor in which the method and system of diagnosis of the present invention can be implemented.

Having described an example of a preferred embodiment, it should be understood that the scope of the present invention encompasses other possible variations and is limited only by the content of the appended claims, including therein the possible equivalents.

Claims

1. A method of diagnosis for refrigeration systems or household appliances, said method comprising the steps of:

(i) Detecting mechanical wave signals of the refrigeration system and of the environment near the system or household appliance, the mechanical waves comprising mechanical oscillations of the surroundings of the refrigeration system or household appliance;

(ii) Generating a spectral signature of the vibration parameters detected in step (i);

(iii) Assessing the operating condition of the components of the refrigeration system or household appliance: wherein the spectral signatures generated in step (ii) are compared with the spectral signatures relating to normal operating conditions of the refrigeration system or household appliance.

2. A method of diagnosis according to claim 1, wherein the operating condition of the components of the refrigeration system or household appliance assessed in step (iii) is registered in a database.

3. A method of diagnosis according to claim 1, wherein the operating condition obtained in step (iii) is made available for viewing through an alert interface.

4. A method of diagnosis according to claim 1, wherein the mechanical waves comprise mechanical oscillations of components of the system, of the refrigeration system as a whole, or of the household appliance.

5. A method of diagnosis according to claim 1, wherein for the different vibration modes of the mechanical wave signals of the refrigeration system or household appliance, the database stores a plurality of spectral signatures relating to the standard operating conditions.

6. A method of diagnosis according to claim 5, wherein, in step (iii), the spectral signature generated from a vibration mode is compared with a plurality of spectral signatures of standard operating conditions, said standard signatures relating to the same mode of oscillation as the spectral signature generated.

7. A diagnosis system for a refrigeration system or household appliances in general, said diagnosis system comprising at least one transducer (2) that is able to detect mechanical wave signals from the components of the refrigeration system as a whole and its surroundings or from the household appliance and its surroundings; and

a digital processing unit (4) that receives the parameters obtained by the transducer (2) and is able to identify spectral patterns from the signals received from the transducer.

8. A diagnosis system according to claim 7, wherein the digital processing unit (4) identifies the current operating condition of the system by comparing the spectral pattern of the signals with preestablished patterns stored in a memory unit (5).

9. A diagnosis system according to claim 7, wherein the digital processing unit (4) stores a record of the operating conditions of the system and identifies its patterns of behavior over time.

10. A diagnosis system according to claim 7, wherein the transducer (2) comprises accelerometers, microphones and audio sensors.

11. A diagnosis system according to claim 7, wherein the alert interface (6) comprises at least one display or terminals for the connection of a reading device.

12. A refrigeration system compressor diagnosed by a method comprising:

(i) Detecting mechanical wave signals of the refrigeration system and of the environment near the system or household appliance, the mechanical waves comprising mechanical oscillations of the surroundings of the refrigeration system or household appliance;

(ii) Generating a spectral signature of the vibration parameters detected in step (i);

(iii) Assessing the operating condition of the components of the refrigeration system or household appliance: wherein the spectral signatures generated in step (ii) are compared with the spectral signatures relating to normal operating conditions of the refrigeration system or household appliance.

13. A refrigeration system compressor diagnosed by a diagnosis system comprising:

at least one transducer (2) that is able to detect mechanical wave signals from the components of the refrigeration system as a whole and its surroundings or from the household appliance and its surroundings; and

a digital processing unit (4) that receives the parameters obtained by the transducer (2) and is able to identify spectral patterns from the signals received from the transducer.