FIELD OF THE INVENTION

The present invention relates to cleanliness determination for an air conditioner, and more particularly, to a system for determining cleanliness of an indoor unit of an air conditioner and a method therefor.

BACKGROUND OF THE INVENTION

In view of growing demand for air conditioning, it becomes important to maintain cleanliness of an air conditioner in order to ensure its maximum life span. Dirt buildup in the air conditioner could cause serious performance and efficiency issues. For example, when an air filter of an air conditioner gets clogged with dirt, it might obstruct cold air from passing through, leading to production of uncomfortably warm air instead of refreshing cold air. Nevertheless, it seems to be troublesome for a person to manually check the cleanliness of the air conditioner on a regular basis as most air conditioners are usually installed at a higher position or near to a ceiling of a building which may not be conveniently accessible.

There have been a number of examples over the prior art aiming to facilitate process of determining cleanliness of the air conditioner without causing hassle to user in order to ensure the air conditioner working at optimum efficiency from time to time. One of the prior art documents is CN107702283B that provides a method of determining cleanliness of an air conditioner based on opening degree of an electronic expansion valve. In this method, the actual opening degree of the electronic expansion valve is obtained to compare with a standard opening degree of the electronic expansion valve that is determined using inlet air temperature of an indoor unit of the air conditioner and outdoor ambient temperature. According to their difference, cleanliness of the indoor unit is determined. Nevertheless, accuracy of such determination method solely based on the opening degree of the electronic expansion valve might be questionable as there are other possibilities that could affect the opening degree of the electronic expansion valve, for example, abnormal refrigerant charging level.

Another prior art document CN1 1041 1086B discloses a method for determining cleanliness of an air conditioner, in particular a method for determining clogging of a filter before an expansion valve in the air conditioner. In this prior art, there are few parameters taken into consideration to determine clogging of the filter, including liquid pipe temperature, gas pipe temperature, opening degree of the expansion valve, inlet temperature of the filter and outlet temperature of the filter. As such method involves more parameters, it requires more sensors or devices for detection. Also, handling of the parameter data seems to involve more complicated process in this method.

Further, prior art document JP2016121867A discloses another method for determining cleanliness of an air conditioner. In detail, cleanliness of filter of an indoor unit is determined by monitoring trend of compressor frequency, outdoor fan speed as well as opening degree of expansion valve over certain operation period. However, this method may require more time for monitoring the trend of these parameters before making judgement. Also, such method may be incapable of providing quick indication on abnormal cleanliness status of the indoor unit filter.

In view of the shortcomings of the prior art documents, there is a need to provide an improved system and method for determining cleanliness of an air conditioner in a more efficient and reliable manner. The improved system shall be capable of reducing misjudgment errors and providing quick response on reporting the cleanliness status to users.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a system that is capable of determining abnormality in performance of an air conditioner caused by cleanliness of an indoor unit of the air conditioner. Another object of the present invention is to provide a system for determining cleanliness of an indoor unit of an air conditioner with an improved accuracy and reliability by taking evaporating temperature of an indoor heat exchanger into consideration.

It is also an object of the present invention to provide a system that allows user to be aware of early sign of poor cleanliness in an indoor unit of an air conditioner so as to prevent degradation in performance of the air conditioner.

A further object of the present invention is to provide a system that facilitates determination of cleanliness of an indoor unit of an air conditioner without involving complicated process of handling different parameter data.

According to an aspect of the present invention, the above objects can be accomplished by the provision of a system for determining cleanliness of an indoor unit of an air conditioner. The system comprising a first detection means for obtaining an indoor wet bulb temperature, a second detection means for obtaining an outdoor ambient temperature, a third detection means for obtaining an evaporating temperature, and a controller having a computing module for computing a reference evaporating temperature using the indoor wet bulb temperature and the outdoor ambient temperature as obtained by the first and second detection means.

The controller further comprising a determining module for determining the cleanliness of the indoor unit. The cleanliness status of the indoor unit is determined as dirty when the evaporating temperature is lower than the reference evaporating temperature.

In a preferred embodiment of the present invention, the computing module computes the reference evaporating temperature by using the equation of: where

T _e denotes the reference evaporating temperature;

Tin denotes the indoor wet bulb temperature;

Tout denotes the outdoor ambient temperature; and a, b, c, d, e and f are constant values.

Preferably, the evaporating temperature is an evaporating temperature of an indoor heat exchanger in the indoor unit of the air conditioner.

Further, the first detection means comprising a temperature sensor and a humidity sensor which are placed in an area where the indoor unit is installed for obtaining the indoor wet bulb temperature. In another embodiment of the present invention, the first detection means is a wet bulb temperature sensor used for obtaining the indoor wet bulb temperature.

Furthermore, the second detection means is preferably a temperature sensor that is placed near an outdoor unit of the air conditioner, preferably an air inlet of the outdoor unit, while the third detection means is preferably a temperature sensor which is arranged at a position on the indoor heat exchanger.

The system further comprising a database for storing a set of precomputed reference evaporating temperatures based on a plurality of indoor wet bulb temperatures and outdoor ambient temperatures. Also, the system further comprising an indicator for providing indication of the cleanliness status of the indoor unit.

It is preferred that the cleanliness of the indoor unit is determined when the operation of the air conditioner is in a predefined condition for a predetermined operating duration of the air conditioner. The predefined condition of the operation of the air conditioner includes having any one or a combination of compressor frequency, indoor unit fan speed and outdoor unit fan speed to be operated within a manufacturer’s predefined operating range. Further, the predetermined operating duration is preferably in a range of 10 to 90 minutes. In a more preferred embodiment of the present invention, the system is to determine cleanliness of the indoor heat exchanger and cleanliness of an air filter of the indoor unit.

According to another aspect of the present invention, there is provided a method for determining cleanliness of the indoor unit of the air conditioner, wherein the method comprising obtaining an indoor wet bulb temperature via a first detection means, obtaining an outdoor ambient temperature via a second detection means, obtaining an evaporating temperature via a third detection means, and computing a reference evaporating temperature using the indoor wet bulb temperature and the outdoor ambient temperature as obtained by the first and second detection means by a computing module of a controller. The cleanliness status of the indoor unit is determined a dirty by a determining module of the controller when the evaporating temperature as obtained is less than the reference evaporating temperature.

BRIEF DESCIRPTION OF THE ACCOMPANYING DRAWINGS

The features of the invention will be readily understood and appreciated from the following detailed description when read in conjunction with the accompanying drawings of the preferred embodiments of the present invention, in which:

Figure 1 illustrates a system for determining cleanliness of an indoor unit of an air conditioner according to a preferred embodiment of the present invention

Figure 2 is a flow chart illustrating steps executed by a system for determining cleanliness of an indoor unit of an air conditioner according to a preferred embodiment of the present invention.

Figure 3(a) is a line chart illustrating relationship between evaporating temperature of an indoor heat exchanger and indoor wet bulb temperature, while Figure 3(b) is a line chart illustrating relationship between evaporating temperature of an indoor heat exchanger and indoor dry bulb temperature.

Figure 4 is a line chart illustrating relationship between evaporating temperature of an indoor heat exchanger and outdoor dry bulb temperature.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The abovementioned and other features and objects of this invention will become more apparent and better understood by reference to the following detailed description. It should be understood that the detailed description made known below is not intended to be exhaustive or limit the invention to the precise form disclosed as the invention may assume various alternative forms. All the relevant modifications and alterations made to the present invention as covered in the detailed description should be construed to fall within the scope of the appended claims. Therefore, the configuration of the invention is not limited to the configuration mentioned in the following description.

The present invention relates to a system (100) for determining cleanliness of an indoor unit of an air conditioner that could affect operation and performance of the air conditioner. The system (100) is provided to aid in detecting poor cleanliness of the indoor unit that may lead to deterioration in the operation and performance of the air conditioner. Further, the system (100) allows the indoor unit to perform self-diagnosis on its cleanliness in order to identify the need of cleaning and maintenance service, so that user is alert to any unnoticeable abnormality in operation and performance of the air conditioner at an early stage that could be caused by dirt accumulation or impurities clogging in the indoor unit.

With reference to Figure 1 , the system (100) of the present invention comprising a first detection means (1 10) for obtaining an indoor wet bulb temperature, a second detection means (1 12) for obtaining an outdoor ambient temperature, a third detection means (114) for obtaining an evaporating temperature and a controller (130) that is configured to process the temperature information as obtained by each detection means so as to determine the cleanliness of the indoor unit.

The controller (130) of the present invention is provided with a computing module (132) for computing a reference evaporating temperature using the indoor wet bulb temperature and the outdoor ambient temperature as obtained by the first and second detection means (110, 1 12). The controller (130) further comprises a determining module (134) for determining the cleanliness of the indoor unit, in which the cleanliness status of the indoor unit is determined as dirty when the evaporating temperature as detected is lower than the reference evaporating temperature. If the evaporating temperature as detected is not lower than the reference evaporating temperature, the cleanliness status of the indoor unit is determined as acceptable.

In a preferred embodiment of the present invention, the computing module (132) is configured for computing the reference evaporating temperature using the equation of: where T _e denotes the reference evaporating temperature; Tin denotes the indoor wet bulb temperature; Tout denotes the outdoor ambient temperature; and, a, b, c, d, e and f are constant values. The constant values could be determined via multiple regression analysis using a plurality of indoor wet bulb temperature data and a plurality of outdoor ambient temperature data as input variables, and a plurality of reference evaporating temperature data as output variable. These temperature data may be obtained under different operating conditions.

In one embodiment of the present invention, the first detection means (110) is preferably comprising a temperature sensor and a humidity sensor disposed in an area where the indoor unit is installed for obtaining the indoor wet bulb temperature. In another embodiment of the present invention, the first detection means (1 10) could be a wet bulb temperature sensor for obtaining the indoor wet bulb temperature. Further, the second detection means (112) is a temperature sensor disposed near an outdoor unit of the air conditioner for obtaining the outdoor ambient temperature. The second detection means (112) is preferably disposed at a position at the air inlet area before air passing an outdoor heat exchanger in the outdoor unit.

The evaporating temperature of the present invention is an evaporating temperature of an indoor heat exchanger in the indoor unit. The evaporating temperature is obtained by the third detection means (1 14) which is preferably a temperature sensor disposed at a position on the indoor heat exchanger. The third detection means (1 14) may be disposed at any position on the indoor heat exchanger where the temperature of the indoor heat exchanger is detectable. Preferably, it may be disposed at a position near the middle part of the indoor heat exchanger.

According to a preferred embodiment of the present invention, the system (100) may further comprising a database (150) for storing a set of pre-computed reference evaporating temperatures based on a plurality of indoor wet bulb temperatures and outdoor ambient temperatures in order to provide quick and accurate result of the reference evaporating temperature. Preferably, the set of pre-computed reference evaporating temperatures are determined based on the plurality of indoor wet bulb temperatures and outdoor ambient temperatures that are obtained under different conditions where the indoor unit is clean. When the computing module (132) receives information of the indoor wet bulb temperature and the outdoor ambient temperature from the first and second detection means (1 10, 1 12), the reference evaporating temperature corresponding to the indoor wet bulb temperature and the outdoor ambient temperature could be found and retrieved from the set of pre-computed reference evaporating temperatures in the database. Storing of the set of pre-computed reference evaporating temperatures in the database (150) could facilitate retrieval of the reference evaporating temperature by the system (100). According to another preferred embodiment of the present invention, the system (100) may further comprising an indicator (140) for providing an indication of the cleanliness status of the indoor unit. The indicator (140) shows the cleanliness status in a form visually and/or audibly noticeable by the user of the system. The indicator (140) may be a LED light which will blink in certain manner to indicate the cleanliness status. It is possible that the indicator (140) to be disposed on a display of the air conditioner unit or a display of a separate remote controller.

Optionally, the indicator (140) could be an application installed in a mobile device which may establish connection with the system (100) in a wireless manner. Users may receive notification on the cleanliness status via the application installed in their mobile device. In a possible embodiment of the present invention, users may use the same application in the mobile device to control the system (100) for determination of cleanliness of the indoor unit. The application in the mobile device may be optionally used to initiate or/and interrupt determination of cleanliness of the indoor unit. On the other hand, the system (100) could be initiated automatically once the air conditioner starts to operate without the need of user input as activation.

In a preferred embodiment of the present invention, the cleanliness of the indoor unit is determined when the operation of the air conditioner is in a predefined condition for a predetermined operating duration of the air conditioner. The predefined condition of the operation of the air conditioner preferably includes having any one or a combination of compressor frequency, indoor unit fan speed and outdoor unit fan speed to be operated within a manufacturer’s predefined operating range. It is important to ensure that the performance of the compressor, the indoor unit fan and/or the outdoor unit fan is in stable and normal state so as to eliminate other possibilities that could affect operation of the indoor unit before determining cleanliness of the indoor unit. Moreover, the predetermined operating duration is preferably in a range of 10 to 90 minutes, more preferably 15 to 60 minutes. But it is possible to have a different predetermined operating duration to suit different specification of air conditioner. In a further embodiment of the present invention, an opening of an expansion valve of the indoor unit is checked to be operated in a predefined range of opening degree before determination of the cleanliness of the indoor unit in order to identity any issue of refrigerant charging.

Another embodiment of the present invention relates to a method for determining cleanliness of the indoor unit of the air conditioner via the aforementioned system (100). The steps of the method have been primarily described and illustrated in the preceding paragraphs. As shown in Figure 2, before the method is initiated by the system (100) at step 220, the operation of the air conditioner is checked to confirm that it is in a predefined condition for a predetermined operation duration to ensure overall operation is stable and normal. This includes having compressor frequency, indoor unit fan speed, and outdoor unit fan speed to be operated within a manufacturer’s predefined operating range for the predetermined operating duration.

After carrying out step 210 for checking the operation of the air conditioner, the method is initiated by the system (100) to perform the determination of cleanliness of the indoor unit of the air conditioner. The method preferably comprises obtaining an indoor wet bulb temperature, an outdoor ambient temperature and an evaporating temperature via the first, second and third detection means (1 10, 1 12, 114) at step 230, and subsequently computing a reference evaporating temperature using the indoor wet bulb temperature and the outdoor ambient temperature as obtained by the first and the second detection means (1 10, 1 12) by the computing module (132) of the controller (130) at step 240. At step 250, the cleanliness status of the indoor unit is determined as dirty by the determining module (134) of the controller (130) when the evaporating temperature as detected is less than the reference evaporating temperature. The system (100) will then provide an indication of the cleanliness status of the indoor unit to user via the indicator (140) at step 260. In a preferred embodiment of the present invention, the method as performed by the system (100) is configured to determine cleanliness of components of the indoor unit which may affect operation of the air conditioner, preferably the indoor heat exchanger and an air filter of the indoor unit. If any of these components is clogged or filled with dirt and dust at early stage, the system (100) is able to detect this issue which is unnoticeable at that stage, and to notify user at the earliest convenience in order to take necessary action, for instance, to initiate self-cleaning function available in the indoor unit or to schedule maintenance service on a timely basis.

Figure 3(a) shows the effect of indoor wet bulb temperature on the evaporating temperature of the indoor heat exchanger, while Figure 3(b) shows the effect of indoor dry bulb temperature, which is also known as indoor ambient temperature, on the evaporating temperature of the indoor heat exchanger. It can be seen that the indoor wet bulb temperature has significant impact on the evaporating temperature, while there is no much impact of the indoor dry bulb temperature on the evaporating temperature. As the indoor wet bulb temperature increases, the evaporating temperature increases. On the other hand, when the indoor dry bulb temperature increases, the evaporating temperature does not change significantly. Thus, by taking the indoor wet bulb temperature into determination of the reference evaporating temperature, the accuracy of determining the cleanliness of the indoor unit can be greatly improved.

Figure 4 shows the effect of outdoor dry bulb temperature on the evaporating temperature of the indoor heat exchanger. The outdoor dry bulb temperature is also commonly known as outdoor ambient temperature. As the outdoor dry bulb temperature increases, the evaporating temperature increases too. It is apparent that the outdoor dry bulb temperature contributes to a significant impact on determination of the reference evaporating temperature and eventually this could improve accuracy of determination of the cleanliness of the indoor unit. Based on Figures 3 and 4, it is apparent that combination of the indoor wet bulb temperature and the outdoor dry bulb temperature is capable of contributing to a higher reliability and accuracy in determining cleanliness of the indoor unit as both parameters are able to reflect the preferred evaporating temperature of the indoor heat exchanger when the indoor unit is in clean condition.

Various modifications to these embodiments are apparent to those skilled in the art from the description and the accompanying drawings. The principles associated with the various embodiments described herein may be applied to other embodiments. Therefore, the description is not intended to be limited to the embodiments shown along with the accompanying drawings but is to be providing broadest scope of consistent with the principles and the novel features disclosed or suggested herein. Accordingly, the invention is anticipated to hold on to all other such alternatives, modifications, and variations that fall within the scope of the present invention and appended claims.