Control method of defrosting function in an air conditioning system

Abstract

Control method of defrosting function in an air conditioning system comprising a central unit (2) and a plurality of peripheral units (3) capable of performing alternatively a heating cycle and a defrosting cycle in which the ice previously formed on a heat exchanger during heating cycle is eliminated, the method including: a) checking (block 100) the status of the peripheral units (3) determining which units have generated an authorization request to start a defrost cycle; b) accumulate (block 110) the defrost requests received from the various units in a FIFO First-in / First Out array; c) determining (block 120) the maximum number NMAX of peripheral units (3) that can be activated at the same time to perform a defrosting cycle; d) checking (block 130) which is the actual number NIST of peripheral units (3) performing a defrost cycle; e) if the actual number of NIST active units is less than the maximum NMAX number, the FIFO array is scanned, thus enabling the peripheral unit that first entered its defrosting request into the array and increasing the number of active units by one; f) repeating steps a) - e) cyclically.

Description

[0001] CONTROL METHOD OF DEFROSTING FUNCTION IN AN AIR CONDITIONING SYSTEM

[0002] Cross-Reference to Related Applications

[0003] This Patent Application claims priority from Italian Patent Application No . 102022000003374 filed on February 23 , 2022 the entire disclosure of which is incorporated herein by reference .

[0004] Technical Field

[0005] The present invention relates to control method of defrosting function in an air conditioning system .

[0006] Background of the Invention

[0007] Air conditioning systems comprising a central unit and a plurality of peripheral units capable of performing alternatively a heating cycle and a defrosting cycle in which the ice previously formed on a heat exchanger during heating cycle is eliminated are well known in the art .

[0008] As it is known, the defrosting cycle is necessary to remove the ice that acts as a thermal barrier between the heat exchanger and the air and deteriorates the performance of the peripheral unit in the heating cycle . During the defrosting cycle the thermal phase is reversed and the peripheral unit produce cooled air .

[0009] In winter time , all the peripheral units operate in the heating cycle and therefore requests of de frosting periodically occur . When a noticeable number of peripheral units operate a defrosting cycle at the same time the central unit may be " stressed" ; moreover the environment where the peripheral unit operate may become too cold and people may feel uncomfortable .

[0010] It is therefore felt the need of providing an air conditioning system permitting the control of the peripheral units so that the above drawbacks may be eliminated .

[0011] CN110195921A discloses a continuously-heating defrosting control method and device, air conditioner unit and equipment . CN113154522A discloses a multi-split air conditioner system and defrosting control method .

[0012] Summary of the Invention

[0013] The above scope is obtained by the present invention that relates to a control method of defrosting function in an air conditioning system as defined in claim 1 .

[0014] Brief Description of the Drawings

[0015] For a better understanding of the present invention, a preferred embodiment is described below, by means o f a nonlimiting example , with reference to the attached drawings in which :

[0016] • Figure 1 schematically shows an air conditioning system; and

[0017] • Figure 2 schematically shows the operations of the method according to the present invention .

[0018] Detailed Description of the Invention

[0019] In figure 1 numeral 1 indicates an air conditioning system ( of known kind and represented schematically) comprising a central unit 2 and a plurality of peripheral units 3 connected with the central unit through respective piping 4 .

[0020] The peripheral units 3 are capable of performing alternatively a heating cycle and a defrosting cycle in which the ice previously formed on a heat exchanger 5 during heating cycle is eliminated .

[0021] Each peripheral unit 3 has known technical means to sense when is time to start a defrost cycle and send a defrosting request ( for instance by means of a wireless system 7 ) towards an electronic unit 6 that controls the peripheral units 3 providing authori zation to defrost according to the operation that shall be described in the following flow chart . Numeral 8 indicates a cable connecting each peripheral unit 3 with the electronic unit 6 .

[0022] Each peripheral unit 3 comprises a number of circuits Cl ...Cn; each circuit ( of known kind) comprises the heat exchanger 5 , a compressor 9 and an expansion valve 10 . The circuit of the same peripheral unit 3 have the same heat exchanger 11 that , in use , is designed to produce warm air in the heating cycle .

[0023] The operation of the method performed by the electronic unit 6 are the following : a ) checking the status (block 100 ) of the peripheral units 3 determining which units are currently carrying out a defrost cycle and which units have generated an authori zation request to start a defrost cycle ; b ) accumulate (block 110 ) the defrost requests received from the various units in a FI FO First-in / First Out array; c ) determining (block 120 ) the maximum number NMAX of units 3 that can be activated at the same time to perform a defrosting cycle ; d) checking (block 130 ) which is the actual number NIST of peripheral units 3 performing a defrost cycle ; e ) i f the actual number of NIS active units is less than the maximum NMAX number, the FI FO array is scanned (block 140 ) , thus enabling the peripheral unit that first entered its defrosting request into the array and increasing the number of active units by one ; f ) repeating steps 100 - 110 cyclically .

[0024] I f the actual number of NIST active units is greater than the maximum N X number, no pending defrosting request may be authori zed and the program goes back to block 100 to see i f the number of peripheral units performing a defrosting cycle has changed . In fact one ( or more ) peripheral unit may have ended the defrosting cycle .

[0025] Block 120 determining the maximum number NMAX of units 3 which can be activated simultaneously to perform a defrost cycle comprises the step of : calculating a first numerical parameter a defined as the ratio between the number of defrost requests coming from di f ferent circuits C of peripheral units 3 and the total number of the circuits of the air condition system; the said first parameter a represents the degree of suf fering of the system namely : a = (number of defrost requests coming from di f ferent circuits C of peripheral units 3 ) / ( the total number of the circuits of the air condition system) calculating a second numerical parameter k as a function of the ratio between total number of the circuits of the air condition system and the total number of peripheral units 3 namely : k = ( total number of the circuits of the air condition system ) / ( the total number of peripheral units 3 ) calculating a third numerical parameter p as a linear function of the second parameter, for instance :

[0026] P = k / 6 + 1 / 3 calculating the percentage of units N% that can be activated to perform simultaneously a defrosting cycle by multiplying the first numerical parameter by the third numerical parameter, namely N% = a * p ; calculating the maximum number NMAX of defrost units 3 that can be activated simultaneously by multiplying the percentage of defrosting units N% by the total number of peripheral units 3 of the system .

[0027] In view of the foregoing, the advantages of defrost control method according to the invention are apparent .

[0028] The proposed logic allows to avoid the defrost of a number of units that may decrease the quality of the arrangement and in order to increase its ef ficiency .

[0029] It is clear that modi fications can be made to the described defrost control method which do not extend beyond the scope of protection defined by the claims . Numerals

[0030] 1 air conditioning system

[0031] 2 central unit

[0032] 3 peripheral units 4 pipings

[0033] 5 heat exchanger

[0034] 6 electronic unit

[0035] 7 wireless

[0036] 8 cable 9 compressor

[0037] 10 expansion valve

[0038] 11 heat exchanger

Claims

CLAIMS1.- Control method of defrosting function in an air conditioning system comprising a central unit (2) and a plurality of peripheral units (3) capable of performing alternatively a heating cycle and a defrosting cycle in which the ice previously formed on a heat exchanger (5) during heating cycle is eliminated, the method being characterized by the fact that it includes the following steps: a) checking (block 100) the status of the peripheral units (3) determining which units are currently carrying out a defrost cycle and which units have generated an authorization request to start a defrost cycle; b) accumulate (block 110) the defrost requests received from the various units in a FIFO First-in / First Out array; c) determining (block 120) the maximum number NMAX of peripheral units (3) that can be activated at the same time to perform a defrosting cycle; d) checking (block 130) which is the actual number NIST of peripheral units (3) performing a defrost cycle; e) if the actual number of NIS active units is less than the maximum NMAX number, the FIFO array is scanned, thus enabling the peripheral unit that first entered its defrosting request into the array and increasing the number of active units by one; f) repeating steps a) - e) cyclically, characterized in that, if the actual number of NIST active units is greater than the maximum N X number, no pending defrosting request may be authorized and step a) is repeated to see if the number of peripheral units performing a defrosting cycle has changed because one or more peripheral unit has ended the defrosting cycle: wherein said step b) of determining the maximum number NMAX of peripheral units (3) which can be activated simultaneously to perform a defrost cycle comprises the stepof : calculating a first numerical parameter a defined as the ratio between the number of defrost requests coming from different circuits C of peripheral units (3) and the total number of the circuits of the air condition system; the said first parameter a represents the degree of suffering of the system namely: a = (number of defrost requests coming from different circuits C of peripheral units (3) ) / (the total number of the circuits of the air condition system) calculating a second numerical parameter k as a function of the ratio between total number of the circuits of the air condition system and the total number of peripheral units (3) namely: k = (total number of the circuits of the air condition system ) / (the total number of peripheral units ( 3 ) ) calculating a third numerical parameter p as a linear function of the second parameter, for instance: P = k / 6 + 1 / 3 calculating the percentage of units N% that can be activated to perform simultaneously a defrosting cycle by multiplying the first numerical parameter by the third numerical parameter, namely N% = a * p; calculating the maximum number NMAX of defrost units (3) that can be activated simultaneously by multiplying the percentage of defrosting units N% by the total number of peripheral units (3) of the system.2.- Method according to claim 1, wherein each peripheral unit (3) comprises a number of circuits Cl ...Cn; each circuit comprises said heat exchanger (5) , a compressor (9) and an expansion valve (10) ; the circuit of the same peripheral unit (3) have a same heat exchanger (11) that, in use, is designed to produce warm air in the heating cycle.

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