Patent Grant
9032749
1. Field of the Invention
The present invention relates to multi-room air conditioning apparatuses and, more particularly, relates to an initialization procedure for an electronic expansion valve that serves as a decompression device for the multi-room air conditioning apparatuses.
2. Description of the Related Art
A refrigerant circuit configuration of a typical multi-room air conditioning apparatus includes a plurality of indoor units and an outdoor unit having a compressor, an outdoor heat exchanger, and a four-way valve for switching a refrigerant flow direction. Also, each indoor unit has an electronic expansion valve for decompressing a condensed refrigerant. The electronic expansion valve is disposed in the outdoor unit, the indoor unit, or a branch box. The compressor, the four-way valve, and the electronic expansion valve are connected to and controlled by a control device, depending on various operating conditions.
In response to an operation command issued by any of the indoor units in the rooms all of which are in a shutdown state, the compressor starts up and delivers a refrigerant, which goes through the four-way valve to the outdoor heat exchanger where, in a cooling mode, the refrigerant is condensed. Then, the refrigerant is decompressed through an electronic expansion valve and is subjected to heat exchange using evaporation action in the indoor unit, and is finally returned to the compressor. In a heating mode, a refrigerant flow is turned by the four-way valve to the opposite direction of that in the cooling mode. Then the refrigerant is condensed at the indoor unit, is decompressed through the electronic expansion valve, and then goes to the outdoor unit where the refrigerant is subjected to heat exchange using evaporation action in the outdoor heat exchanger and is finally returned to the compressor.
The electronic expansion valve can adjust the decompression degree and the amount of refrigerant circulation by changing the valve opening degree. The electronic expansion valve corresponding to the indoor unit which has issued the operation command is controlled with regard to the valve opening degree by monitoring the rotational speed of the compressor, discharge temperatures, the degree of supercooling, and the like so as to provide a proper refrigerating cycle. Other electronic expansion valves corresponding to indoor units which have issued no operation command are also controlled not to full close but to slight opening degree so as to prevent valve sticking or refrigerant pooling.
As described above, in order to provide valve opening degree control for the electronic expansion valve, the opening degrees of all of the electronic expansion valves are all closed so as to adjust the zero (starting) point before the refrigeration cycle is activated. This operation is referred to the initialization of the electronic expansion valve.
A specific initialization control operation is described below. Assuming that the electronic expansion valve that has not yet been initialized had a full open opening degree A, the control device issues a command for closing the electronic expansion valve by the amount of −A or more. This operation inevitably results in adjusting zero point, regardless of any opening degree before the initialization. This operation takes a few seconds for each electronic expansion valve.
When the initialization of the electronic expansion valves does not complete, the procedure for activating the refrigerating cycle is as follows: First, all of the electronic expansion valves are initialized. Then, immediately after activation of the compressor following the completion of the expansion valve initialization, the electronic expansion valves is operated and set to a predetermined opening degree.
However, the more the number of the indoor units to be connected to the entire system increase, the more the number of the corresponding electronic expansion valves increase. As described above, the completion of the initialization of all the electronic expansion valves followed by the activation of the compressor results in a significant loss of time from the issuance of an operation command until the activation of the refrigerating cycle.
The relationship between the refrigerating cycle operation and the electronic expansion valve initialization of conventional multi-room air conditioning apparatuses is disclosed in Patent Literature 1 and Patent Literature 2.
Patent Literature 1 discloses a multi-room air conditioning apparatus employing an electronic expansion valve that allows a certain amount of a refrigerant to flow even at the fully closed opening degree for the purpose of fully closing the electronic expansion valves for initialization without suspending the compressor during the system operation.
Patent Literature 2 discloses a multi-room air conditioning apparatus in which a plurality of electronic expansion valves are arranged so as to correspond to one indoor unit, one of which is initialized in advance to provide a predetermined opening after the initialization and subsequently the remaining electronic expansion valves are preformed the same operation in order, for the purpose of fully closing the electronic expansion valves for initialization without suspending the compressor during the system operation.
However, these publications disclose a procedure for initializing the electronic expansion valves without suspending the compressor during the system operation, but do not disclose electronic expansion valves initialization procedure to be performed before the system operation, namely, before the activation of the compressor.
To initiate the refrigerating cycle when the electronic expansion valves have not yet been initialized, first, all of the electronic expansion valves are initialized. Then, immediately after activation of the compressor following the completion of the expansion valve initialization, each electronic expansion valve proceeds to a step of adjusting to a predetermined opening degree.
However, the multi-room air conditioning apparatus has recently showed a tendency toward further increasing number of indoor units. The increasing number of indoor units causes the corresponding electronic expansion valves to also increase in number. Since it takes several seconds to initialize one electronic expansion valve, one-by-one initialization of all the electronic expansion valves requires several tens of seconds to several minutes if a great number of indoor units are provided. This initialization followed by the activation of the compressor will lead to a significant loss of time from the issuance of an operation command until the activation of the refrigerating cycle, giving inconvenience to users who want sooner start-up of cooling/heating capabilities.
To solve this problem, simultaneous initialization of more than one electronic expansion valve is conceivable, but it will result in the necessity for more complicated electronic expansion valve control devices, leading to increased costs.
The present invention has been achieved in light of the foregoing and an object thereof is to provide a multi-room air conditioning apparatus which, without using a complicated control device for simultaneously controlling the opening degree of a plurality of electronic expansion valves, reduces a waiting time associated with the initialization of the electronic expansion valves to be performed before the activation of the compressor, thereby reducing a loss of time until the activation of a refrigerating cycle and giving no inconvenience to users.
A multi-room air conditioning apparatus according to a first aspect of the present invention includes a plurality of indoor units, a compressor, an outdoor heat exchanger, a four-way valve, a plurality of electronic expansion valves corresponding to the plurality of indoor units, respectively, and a control device for controlling the compressor, the outdoor heat exchanger, the four-way valve, the plurality of indoor units, and the plurality of electronic expansion valves, wherein the control device performs the following processing steps of activating a refrigerating cycle when the opening degree of the electronic expansion valves has not yet been initialized:
(a) Each opening degree of only electronic expansion valves corresponding to all of the indoor units which have issued an operation command is initialized; (b) after the initialization is completed for all of the electronic expansion valves corresponding to all of the indoor units which have issued an operation command, the compressor is activated; (c) every opening degree of the electronic expansion valves whose initialization has been completed is adjusted to a predetermined operational opening degree; (d) the opening degree of electronic expansion valves corresponding to indoor units which have issued no operation command is initialized and is adjusted to a predetermined opening degree.
A multi-room air conditioning apparatus according to a second aspect of the present invention includes a sensor for sensing a compressor discharge temperature, wherein, if the discharge temperature abnormally rises when the opening degree of electronic expansion valves corresponding to indoor units which have issued no operation command is being initialized, the control device has a function to suspend closing of such electronic expansion valves for a certain period of time and to maintain the current opening degree for a certain period of time.
A first aspect of the present invention has the effect of reducing a waiting time associated with the initialization of the electronic expansion valves to be performed before the activation of the compressor of a multi-room air conditioning apparatus without using a complicated control device for simultaneously controlling the opening degree of the plurality of electronic expansion valves, thereby reducing a loss of time until the activation of the refrigerating cycle and giving no inconvenience to users.
A second aspect of the present invention has the effect of preventing an ejection of a compressor oil from the compressor due to a rapid temperature rise of the refrigerant that is envisioned at the time of the initialization of the electronic expansion valves corresponding to indoor units which have issued no operation command in the first aspect, thereby avoiding a risk of damage to the compressor.
Four refrigerant circuit configurations applicable to a multi-room air conditioning apparatus according to the present invention are shown in
In addition, the outdoor unit 9 is provided on the upper portion of the compressor shell or on the discharge tubes with a discharge temperature sensor 7 for sensing the temperature of a refrigerant discharged through the compressor. The control device 6 can receive temperature information provided by the discharge temperature sensor 7.
Like that of Embodiment 1, the outdoor unit 9 is provided on the upper portion of the compressor shell or on the discharge tubes or the like with a discharge temperature sensor 7 for sensing the temperature of a refrigerant discharged through the compressor. The control device 6 can receive temperature information provided by the discharge temperature sensor 7.
Like those of Embodiments 1 and 2, the outdoor unit 9 is provided on the upper portion of the compressor shell or on the discharge tubes or the like with a discharge temperature sensor 7 for sensing the temperature of a refrigerant discharged through the compressor. The control device 6 can receive temperature information provided by the discharge temperature sensor 7.
Like those of Embodiments 1 to 3, the outdoor unit 9 is provided on the upper portion of the compressor shell or on the discharge tubes or the like with a discharge temperature sensor 7 for sensing the temperature of a refrigerant discharged through the compressor. The control device 6 can receive temperature information provided by the discharge temperature sensor 7.
An electronic expansion valve opening degree initialization procedure for the multi-room air conditioning apparatus shown in
In the case of a multi-room air conditioning apparatus provided with an electronic expansion valve 13 having no corresponding indoor unit (see
If there are not many indoor units that have issued an operation command, Embodiments 1 to 4 allow the compressor to be activated sooner as compared to the case where the compressor is activated after the completion of electronic expansion valve initialization. This allows speedier start-up of cooling/heating capabilities, giving no inconvenience to users.
In a multi-room air conditioning apparatus configured as in
In order to solve this problem, an electronic expansion valve initialization procedure for preventing an ejection of a lubricating oil from the compressor due to the abrupt temperature rise of the refrigerant in the compressor and thereby avoiding a risk of damage to the compressor is described below on the basis of
In the flowchart of
Please note that
As shown in
As described above, in Embodiments 1 to 4, if, after the compressor is activated, an attempt is made to initialize an electronic expansion valve corresponding to an indoor unit which has issued no operation command, application of processing steps of
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