CN114251896A - Refrigerator and defrosting control method thereof - Google Patents

Abstract

The invention discloses a refrigerator and a defrosting control method thereof, which can establish the corresponding relation between the frosting amount of an evaporator and the temperature difference between the evaporator and a compartment by utilizing the correlation between the frosting on the surface of the evaporator and the reference temperature difference between the temperature of the evaporator and the temperature of the compartment when a compressor is stopped when the refrigerator is in a refrigeration cycle. When the refrigerator is in the shutdown moment of the compressor in the refrigeration cycle, the temperature of the evaporator is detected and compared with the initial temperature difference, the frost amount of the evaporator is indirectly judged according to the comparison result, and defrosting is started timely. Can accurately discern the evaporimeter degree of frosting, open the defrosting heating pipe at better moment and change the frost to the evaporimeter, avoid too early defrosting to cause the energy extravagant, also avoid changing the frost untimely refrigerator refrigeration performance that leads to worsen, realize changing the frost as required in the in-service use process.

Description

Refrigerator and defrosting control method thereof

Technical Field

The invention relates to the technical field of refrigerator control, in particular to a refrigerator and a defrosting control method thereof.

Background

The defrosting energy consumption accounts for 10% -20% of the operation energy consumption of the air-cooled refrigerator, and the energy efficiency index of the whole refrigerator can be remarkably improved by optimizing the defrosting control of the refrigerator. At present, the defrosting judgment condition commonly adopted by refrigerator products is the accumulated running time of a complete machine or a compressor, and the defrosting judgment condition is also called as a variable defrosting period control method. Namely: a minimum defrosting time tmin and a maximum defrosting time tmax are set. In detail, defrosting intervals of different environment temperatures/humidities, set gears and door opening and closing time are respectively set according to experience, a defrosting heater is started to defrost when the defrosting time set by a program is reached, and the defrosting heater is stopped after frost is judged to be completely frosted, refrigeration is resumed, and the process is repeated.

The defrosting method using time as a control parameter cannot accurately capture the actual frosting amount of the surface of the evaporator under different working conditions, and has the problems of premature defrosting, untimely defrosting and the like. For example, when a user actually uses the evaporator, frost formation of the evaporator can be accelerated by putting high-water-content food or frequently opening and closing the door, and when the defrosting time interval set by a program is not reached, frost layers on the surface of the evaporator are excessively accumulated to influence normal heat exchange, so that the refrigerating efficiency is reduced; when a user does not put food or open the door for a long time, the evaporator frosts less, the heat exchange performance is not obviously reduced when the defrosting time interval meets the program setting, and the problems that the energy consumption of the refrigerator is increased due to premature defrosting, the food quality is influenced by frequent defrosting and temperature rise and the like are caused.

Disclosure of Invention

The embodiment of the invention aims to provide a refrigerator and a defrosting control method thereof, which can accurately identify the frosting degree of an evaporator, open a defrosting heating pipe to defrost the evaporator at a better time, avoid energy waste caused by premature defrosting, avoid the refrigeration performance deterioration of the refrigerator caused by untimely defrosting, and realize defrosting as required in the actual use process.

To achieve the above object, an embodiment of the present invention provides a refrigerator, including:

the cold air circulating system comprises an evaporator and a fan, the evaporator is arranged between the box body air duct and the inner container, the fan is positioned at the upper part of the evaporator, and the fan transfers the cold energy of the evaporator into the compartment through air circulation;

the controller is configured to:

after the refrigerator is defrosted, respectively acquiring reference temperature differences of the evaporator temperature and the compartment temperature of a compressor at the stop moment in the first M refrigeration cycles of the refrigerator; the first M refrigeration cycles are all refrigeration cycles executed by the refrigerator after defrosting, and the reference temperature differences corresponding to the first M refrigeration cycles are all obtained when a preset temperature difference obtaining condition is met;

calculating an initial temperature difference according to the reference temperature difference;

when the refrigerator is in the Nth refrigeration cycle and the temperature difference obtaining condition is met, obtaining the real-time temperature difference between the evaporator temperature and the compartment temperature of the refrigerator at the stop moment of the compressor in the current refrigeration cycle; wherein N is more than or equal to 4, N is more than M, and N and M are integers;

and determining the defrosting requirement of the evaporator according to the temperature difference value between the real-time temperature difference and the initial temperature difference, and performing defrosting operation on the evaporator when the defrosting requirement meets a preset defrosting condition.

As an improvement of the above, the controller is further configured to:

starting with the current refrigeration cycle, and acquiring a temperature difference value between the real-time temperature difference and the initial temperature difference in each refrigeration cycle after at least one continuous refrigeration cycle; then, the determining the defrosting requirement of the evaporator according to the temperature difference value between the real-time temperature difference and the initial temperature difference comprises:

when the temperature difference value corresponding to each refrigeration cycle is greater than or equal to a preset temperature difference threshold value, determining that the defrosting requirement is defrosting;

and when the temperature difference value corresponding to any refrigeration cycle is smaller than a preset temperature difference threshold value, determining that the defrosting requirement is that defrosting is not needed.

As an improvement of the above, the calculating an initial temperature difference according to the reference temperature difference includes:

taking the average value of all the reference temperature differences as the initial temperature difference.

As an improvement of the above scheme, the temperature difference obtaining condition is that no user operation is detected in the current refrigeration cycle; the user operation comprises at least one of a refrigerator door opening action, a gear changing action and a forced stopping action.

As an improvement of the above, the controller is further configured to:

acquiring the real-time temperature of the evaporator in the defrosting operation process;

and when the real-time temperature is greater than or equal to a preset defrosting exit temperature, exiting the defrosting mode.

In order to achieve the above object, an embodiment of the present invention further provides a refrigerator defrosting control method, including:

after the refrigerator is defrosted, respectively acquiring reference temperature differences of the evaporator temperature and the compartment temperature of a compressor at the stop moment in the first M refrigeration cycles of the refrigerator; the first M refrigeration cycles are all refrigeration cycles executed by the refrigerator after defrosting, the reference temperature differences corresponding to the first M refrigeration cycles are all acquired when a preset temperature difference acquisition condition is met, N is more than or equal to 4, N is more than M, and N and M are integers;

calculating an initial temperature difference according to the reference temperature difference;

when the refrigerator is in the Nth refrigeration cycle and the temperature difference obtaining condition is met, obtaining the real-time temperature difference between the evaporator temperature and the compartment temperature of the refrigerator at the stop moment of the compressor in the current refrigeration cycle; wherein N is more than or equal to 4, N is more than M, and N and M are integers;

and determining the defrosting requirement of the evaporator according to the temperature difference value between the real-time temperature difference and the initial temperature difference, and performing defrosting operation on the evaporator when the defrosting requirement meets the preset defrosting condition.

As an improvement of the above, the method further comprises:

starting with the current refrigeration cycle, and acquiring a temperature difference value between the real-time temperature difference and the initial temperature difference in each refrigeration cycle after at least one continuous refrigeration cycle; then, the determining the defrosting requirement of the evaporator according to the temperature difference value between the real-time temperature difference and the initial temperature difference comprises:

when the temperature difference value corresponding to each refrigeration cycle is greater than or equal to a preset temperature difference threshold value, determining that the defrosting requirement is defrosting;

and when the temperature difference value corresponding to any refrigeration cycle is smaller than a preset temperature difference threshold value, determining that the defrosting requirement is that defrosting is not needed.

As an improvement of the above, the calculating an initial temperature difference according to the reference temperature difference includes:

taking the average value of all the reference temperature differences as the initial temperature difference.

As an improvement of the above scheme, the temperature difference obtaining condition is that no user operation is detected in the current refrigeration cycle; the user operation comprises at least one of a refrigerator door opening action, a gear changing action and a forced stopping action.

As an improvement of the above, the method further comprises:

acquiring the real-time temperature of the evaporator in the defrosting operation process;

and when the real-time temperature is greater than or equal to a preset defrosting exit temperature, exiting the defrosting mode.

Compared with the prior art, the refrigerator and the defrosting control method thereof disclosed by the embodiment of the invention can establish the corresponding relation between the frosting amount of the evaporator and the temperature difference between the evaporator and the compartment by utilizing the correlation between the frosting on the surface of the evaporator and the reference temperature difference between the temperature of the evaporator and the temperature of the compartment at the stop moment of the compressor when the refrigerator is in a refrigerating cycle. When the refrigerator is in the shutdown moment of the compressor in the refrigeration cycle, the temperature of the evaporator is detected and compared with the initial temperature difference, the frost amount of the evaporator is indirectly judged according to the comparison result, and defrosting is started timely. Can accurately discern the evaporimeter degree of frosting, open the defrosting heating pipe at better moment and change the frost to the evaporimeter, avoid too early defrosting to cause the energy extravagant, also avoid changing the frost untimely refrigerator refrigeration performance that leads to worsen, realize changing the frost as required in the in-service use process.

Drawings

Fig. 1 is a schematic structural diagram of a refrigerator according to an embodiment of the present invention;

fig. 2 is a flowchart illustrating an operation of a controller in a refrigerator according to an embodiment of the present invention;

fig. 3 is another operation flowchart of the controller in the refrigerator according to the embodiment of the present invention;

fig. 4 is a flowchart of a refrigerator defrosting control method according to an embodiment of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Referring to fig. 1, fig. 1 is a schematic structural diagram of a refrigerator according to an embodiment of the present invention, where the refrigerator includes:

the cold air circulating system 10 comprises an evaporator and a fan, the evaporator is arranged between the box body air duct and the inner container, the fan is positioned at the upper part of the evaporator, and the fan transfers the cold energy of the evaporator into a compartment through air circulation;

the controller 20 is configured to:

after the refrigerator is defrosted, respectively acquiring reference temperature differences of the evaporator temperature and the compartment temperature of a compressor at the stop moment in the first M refrigeration cycles of the refrigerator; the first M refrigeration cycles are all refrigeration cycles executed by the refrigerator after defrosting, and the reference temperature differences corresponding to the first M refrigeration cycles are all obtained when a preset temperature difference obtaining condition is met;

calculating an initial temperature difference according to the reference temperature difference;

when the refrigerator is in the Nth refrigeration cycle and the temperature difference obtaining condition is met, obtaining the real-time temperature difference between the evaporator temperature and the compartment temperature of the refrigerator at the stop moment of the compressor in the current refrigeration cycle; wherein N is more than or equal to 4, N is more than M, and N and M are integers;

and determining the defrosting requirement of the evaporator according to the temperature difference value between the real-time temperature difference and the initial temperature difference, and performing defrosting operation on the evaporator when the defrosting requirement meets a preset defrosting condition.

For example, the conventional air-cooled refrigerator mainly includes a refrigeration system including a compressor, a condenser, a capillary tube, and an evaporator, a cold air circulation system including an evaporator, a fan, an air duct, and a compartment, and a control system. The evaporator is arranged between the box body air duct and the inner container, the fan is located on the upper portion of the evaporator, and when the fan operates, the cold quantity of the evaporator is transferred into the compartment through air circulation, so that the refrigerating and cooling processes are achieved. In addition, the bottom of the evaporator is provided with a defrosting heating pipe, and when a defrosting command is received, the defrosting heating pipe is electrified to generate heat so that frost condensed on the evaporator is melted into water and drips and is discharged outside the box body. An evaporation temperature sensor is arranged on an inlet pipeline of the evaporator, so that the temperature of the evaporator can be detected in real time and is transmitted back to the controller for judgment. The refrigerator is characterized in that a compartment temperature sensor is arranged on the inner container of the refrigerator body, and the refrigerator is controlled to be started and stopped through the detected temperature change, so that the compartment is maintained in a periodically fluctuating temperature range.

During the actual operation of the refrigerator, at the end of a refrigeration cycle, the compressor needs to be stopped at this time, and the difference Δ T (Δ T-tff-Tevap) between the evaporation temperature Tevap and the room temperature Tf at the stop time of the compressor increases as the amount of frost increases. In the process, the refrigerator undergoes a total of 3 operating states: 1) and (3) a stable operation stage: the evaporator gradually frosts, and Tf, Tevap and delta T are unchanged at the shutdown time; 2) a refrigeration performance reduction stage: along with the thickening of the frost layer, the heat exchange performance of the evaporator is deteriorated, the shutdown time Tf is unchanged, Tevap is gradually reduced, and delta T is increased; 3) temperature rise stage of the freezing chamber: along with the frosting heat exchange deterioration of the evaporator, the provided cold quantity is not enough to maintain the low temperature in the box, the compressor is forcibly stopped due to protection, the stop moment Tf is increased, Tevap is reduced, and the delta T is rapidly increased. Therefore, the stop time Δ T indirectly reflects the degree of frosting of the evaporator, and can be used as an identification parameter for defrosting control. By utilizing the characteristic, the corresponding relation between the frost formation amount of the evaporator and the temperature difference delta T at the shutdown time can be established. The frost amount of the evaporator is indirectly judged by detecting the change of the temperature difference value at the shutdown time, and the defrosting is started in time.

Optionally, the calculating an initial temperature difference according to the reference temperature difference includes:

taking the average value of all the reference temperature differences as the initial temperature difference.

Optionally, the controller 20 is further configured to:

acquiring the real-time temperature of the evaporator in the defrosting operation process;

and when the real-time temperature is greater than or equal to a preset defrosting exit temperature, exiting the defrosting mode.

Specifically, referring to fig. 2, when N is 4 and M is 3, after the refrigerator finishes defrosting once, the refrigerator enters a refrigeration cycle again, and after 3 refrigeration cycles have elapsed, reference temperature differences Δ T1, Δ T2 and Δ T3 between the evaporator temperature and the compartment temperature are recorded at the end time of the 3 refrigeration cycles respectively; calculating an average value Δ T0 ═ Aveg (Δ T1, Δ T2, Δ T3) of the reference temperature difference, Δ T0 being an initial temperature difference; then, detecting the real-time temperature difference delta Tn between the temperature of the evaporator and the temperature of the room at the end of each refrigeration cycle; and comparing the difference between the real-time temperature difference delta Tn and the initial temperature difference delta T0, and when the delta Tn-delta T0 is larger than or equal to a, determining that the evaporator has a defrosting requirement, starting a defrosting heating component, and heating the evaporator. And detecting the temperature of the evaporator in the heating process, and exiting the defrosting mode when the temperature of the evaporator reaches a preset defrosting exit temperature Th. And after refrigeration is recovered, the initial temperature difference delta T0 is collected and calculated again.

Optionally, the temperature difference obtaining condition is that no user operation is detected in the current refrigeration cycle; the user operation comprises at least one of a refrigerator door opening action, a gear changing action and a forced stopping action.

For example, in order to avoid influence on stability of the reference temperature difference data caused by opening and closing of a door, gear adjustment, and forced shutdown of a user, before the reference temperature difference data is collected each time, it is necessary to determine whether a user operation exists in the refrigeration cycle (i.e., from the end time of the previous refrigeration cycle to the end time of the refrigeration cycle), and if so, the user operation is skipped over the cycle and is not collected. In addition, 3 sets of reference temperature difference data collected cumulatively need to be subjected to error analysis. If the difference between the maximum value and the minimum value in the reference temperature difference exceeds 0.2 ℃, the 1 st group of data is abandoned, and the reference temperature difference at the end moment of the next refrigeration cycle is collected again for re-judgment until all the reference temperature difference data meet the requirement that the error does not exceed the preset temperature difference error (for example, the temperature difference error is 0.2 ℃). The defrosting exit temperature Th is related to the evaporator structure and the assembling manner, and can be determined through experiments, and the present invention is not particularly limited herein. And monitoring the temperature of the evaporator in real time, and when the temperature of the evaporator reaches a preset defrosting exit temperature Th, indicating that the frost layer on the evaporator is completely evaporated at the moment, exiting the defrosting mode and entering a periodic refrigeration process.

It is worth mentioning that in the running process of the refrigerator, whether the evaporator is frost-blocked or not needs to be monitored, if the refrigeration is finished in a mode of the compressor protection shutdown in two continuous periods without opening and closing the door and adjusting the gear, the evaporator is considered to be covered by a frost layer, the heat exchange is poor, and the defrosting needs to be executed immediately. The refrigerator also comprises a timing module which is used for collecting the running time of the whole refrigerator, defrosting is executed after the running time of the whole refrigerator exceeds the set maximum running time tm, tm is determined by a designer through a specific prototype test, and in the embodiment, tm is set to be 120 h.

Further, referring to fig. 3, the controller 20 is further configured to:

starting with the current refrigeration cycle, and acquiring a temperature difference value between the real-time temperature difference and the initial temperature difference in each refrigeration cycle after at least one continuous refrigeration cycle; then, the determining the defrosting requirement of the evaporator according to the temperature difference value between the real-time temperature difference and the initial temperature difference comprises:

when the temperature difference value corresponding to each refrigeration cycle is greater than or equal to a preset temperature difference threshold value, determining that the defrosting requirement is defrosting;

and when the temperature difference value corresponding to any refrigeration cycle is smaller than a preset temperature difference threshold value, determining that the defrosting requirement is that defrosting is not needed.

For example, a difference between the real-time temperature difference Δ Tn and the initial temperature difference Δ T0 at this time is determined, so as to avoid misdetermination caused by a single sampling error, for example, it is set that when the determination results of D consecutive refrigeration cycles (D being the current refrigeration cycle + passing through at least one consecutive refrigeration cycle) are all greater than a, defrosting is started, for example, D is 3.

Furthermore, in order to further increase the applicability of the scheme under variable working conditions, a self-adaptive adjusting method of the temperature difference threshold value a is added. The temperature difference threshold value a satisfies the following formula:

a＝a0+f(Tan-Ta0)+f(Gn-G0)+f(Fn-F0)；

a0＝f(Ta0,G0,F0)；

wherein a is the temperature difference threshold; a0 is the defrosting temperature difference increment corresponding to the initial temperature difference; ta0 is the environmental temperature of the last refrigeration cycle in the M refrigeration cycles, and Tan is the environmental temperature of the nth refrigeration cycle; g0 is the refrigerator gear of the last refrigerating cycle in the M refrigerating cycles, and Gn is the refrigerator gear of the nth refrigerating cycle; f0 is the compressor speed of the last refrigeration cycle in M refrigeration cycles, Fn is the compressor speed of the nth refrigeration cycle; f (Tan-Ta0) is a correction value corresponding to the change of the environmental temperature; f (Gn-G0) is a correction value corresponding to the gear change; f (Fn-F0) is a correction value corresponding to the change in the compressor rotational speed.

For example, when the initial temperature difference Δ T0 is calculated according to the first 3(M ═ 3) refrigeration cycles, the loop temperature Ta0, the gear G0 and the compressor speed F0 of the last (mth) refrigeration cycle in the first 3 refrigeration cycles are recorded at the same time, and the corresponding defrosting temperature difference increment a0 in this operating condition is calculated, where N ═ 4, M ═ 3 and D ═ 3. Then, at the end of each refrigeration cycle, acquiring a real-time temperature difference Δ Tn, a loop temperature Tan, a gear Gn and a compressor rotation speed Fn, and calculating a defrosting temperature difference increment a, for example, judging whether Δ T4- Δ T0 is greater than or equal to a once in the 4 th refrigeration cycle (at this time, n is 4), and continuously judging whether Δ T5- Δ T0 in the 5 th refrigeration cycle is greater than or equal to a and whether Δ T6- Δ T0 in the 6 th refrigeration cycle is greater than or equal to a because D is 3, if the temperature difference value is greater than or equal to the temperature difference threshold value a in the 4-6 refrigeration cycles, it is indicated that the evaporator has a large frost amount, and defrosting is required. In the process, if the 4 th refrigeration cycle is met and the 5 th refrigeration cycle is not met, the 6 th refrigeration cycle is taken as the current cycle, and whether the corresponding temperature difference values in the D continuous refrigeration cycles are larger than or equal to the temperature difference threshold value or not is calculated again until the temperature difference values corresponding to the D continuous refrigeration cycles are larger than or equal to the temperature difference threshold value, and the defrosting requirement is determined to be defrosting.

Compared with the prior art, the refrigerator disclosed by the embodiment of the invention can establish the corresponding relation between the frosting amount of the evaporator and the temperature difference between the evaporator and the compartment by utilizing the correlation between the frosting amount on the surface of the evaporator and the reference temperature difference between the temperature of the evaporator and the temperature of the compartment at the stop moment of the compressor when the refrigerator is in the refrigeration cycle. When the refrigerator is in the shutdown moment of the compressor in the refrigeration cycle, the temperature of the evaporator is detected and compared with the initial temperature difference, the frost amount of the evaporator is indirectly judged according to the comparison result, and defrosting is started timely. Can accurately discern the evaporimeter degree of frosting, open the defrosting heating pipe at better moment and change the frost to the evaporimeter, avoid too early defrosting to cause the energy extravagant, also avoid changing the frost untimely refrigerator refrigeration performance that leads to worsen, realize changing the frost as required in the in-service use process.

In the embodiment of the invention, the temperature difference between the evaporator temperature and the compartment temperature is collected at the shutdown time, the temperature difference amplification is judged at each shutdown time, the thickness of the frost layer on the evaporator is indirectly predicted, and defrosting is switched in at a proper time, so that the function of defrosting the refrigerator as required is realized; the initial temperature difference is acquired and calculated based on the actual running state of the refrigerator after defrosting is completed every time, so that the judgment error of frosting amount caused by uncertain factors such as air duct assembly, sensor error and fluctuation of controller hardware parameters in batch production, gradual reduction of refrigerator use performance and the like due to different food storage amounts and different food stacking modes of users is avoided, and the detection accuracy is improved.

In addition, the refrigerator comprehensively considers the influence on the temperature difference when the factors such as door opening of a user, gear adjustment, environment temperature change, compressor control and the like change, and the temperature difference increment a can be subjected to self-adaptive calculation adjustment when the refrigerator runs under the interference factors, so that the defrosting cut-in time under a new working condition is accurately judged; defrosting judgment only needs to detect the temperature of the evaporator, the temperature of the room and the ambient temperature at the shutdown time, and reads gear and compressor rotating speed information, and does not need to collect data regularly or frequently for judgment, so that the data collection processing amount is small, the operation is simple, and the control is stable and reliable. Before data acquisition, whether the refrigerator operates in an unstable state is discriminated, and if so, skipping and not judging is carried out. Whether the evaporator is in a frost blocking state or not is detected in real time, and if yes, defrosting is immediately executed, so that the influence of temperature rise of the room temperature on food preservation is prevented.

Referring to fig. 4, fig. 4 is a flowchart of a refrigerator defrosting control method according to an embodiment of the present invention, where the refrigerator defrosting control method includes:

s1, respectively acquiring reference temperature differences of the evaporator temperature and the compartment temperature of the compressor at the stop moment in the first M refrigeration cycles of the refrigerator after the refrigerator is defrosted; the first M refrigeration cycles are all refrigeration cycles executed by the refrigerator after defrosting, and the reference temperature differences corresponding to the first M refrigeration cycles are all obtained when a preset temperature difference obtaining condition is met;

s2, calculating an initial temperature difference according to the reference temperature difference;

s3, when the refrigerator is in the Nth refrigeration cycle and the temperature difference obtaining condition is met, obtaining the real-time temperature difference between the evaporator temperature and the compartment temperature of the refrigerator at the stop moment of the compressor in the current refrigeration cycle; wherein N is more than or equal to 4, N is more than M, and N and M are integers;

s4, determining the defrosting requirement of the evaporator according to the temperature difference value between the real-time temperature difference and the initial temperature difference, and when the defrosting requirement meets the preset defrosting condition, carrying out defrosting operation on the evaporator.

For example, during the actual operation of the refrigerator, at the end of a refrigeration cycle, the compressor needs to be shut down at this time, and the difference Δ T (Tf-Tevap) between the evaporating temperature Tevap and the compartment temperature Tf at the time of the shutdown of the compressor increases as the amount of frost increases. In the process, the refrigerator undergoes a total of 3 operating states: 1) and (3) a stable operation stage: the evaporator gradually frosts, and Tf, Tevap and delta T are unchanged at the shutdown time; 2) a refrigeration performance reduction stage: along with the thickening of the frost layer, the heat exchange performance of the evaporator is deteriorated, the shutdown time Tf is unchanged, Tevap is gradually reduced, and delta T is increased; 3) temperature rise stage of the freezing chamber: along with the frosting heat exchange deterioration of the evaporator, the provided cold quantity is not enough to maintain the low temperature in the box, the compressor is forcibly stopped due to protection, the stop moment Tf is increased, Tevap is reduced, and the delta T is rapidly increased. Therefore, the stop time Δ T indirectly reflects the degree of frosting of the evaporator, and can be used as an identification parameter for defrosting control. By utilizing the characteristic, the corresponding relation between the frost formation amount of the evaporator and the temperature difference delta T at the shutdown time can be established. The frost amount of the evaporator is indirectly judged by detecting the change of the temperature difference value at the shutdown time, and the defrosting is started in time.

Optionally, in step S2, the calculating an initial temperature difference according to the reference temperature difference includes:

taking the average value of all the reference temperature differences as the initial temperature difference.

Optionally, the refrigerator defrosting control method further includes S5 to S6:

s5, acquiring the real-time temperature of the evaporator in the defrosting operation process;

and S6, when the real-time temperature is greater than or equal to the preset defrosting exit temperature, exiting the defrosting mode.

Specifically, referring to fig. 2, when N is 4 and M is 3, after the refrigerator finishes defrosting once, the refrigerator enters a refrigeration cycle again, and after 3 refrigeration cycles, reference temperature differences Δ T1, Δ T2 and Δ T3 between the evaporator temperature and the compartment temperature are recorded at the end time of the 3 refrigeration cycles respectively; calculating an average value Δ T0 ═ Aveg (Δ T1, Δ T2, Δ T3) of the reference temperature difference, Δ T0 being an initial temperature difference; then, detecting the real-time temperature difference delta Tn between the temperature of the evaporator and the temperature of the room at the end of each refrigeration cycle; and comparing the difference between the real-time temperature difference delta Tn and the initial temperature difference delta T0, and when the delta Tn-delta T0 is larger than or equal to a, determining that the evaporator has a defrosting requirement, starting a defrosting heating component, and heating the evaporator. And detecting the temperature of the evaporator in the heating process, and exiting the defrosting mode when the temperature of the evaporator reaches a preset defrosting exit temperature Th. And after refrigeration is recovered, the initial temperature difference delta T0 is collected and calculated again.

Optionally, the temperature difference obtaining condition is that no user operation is detected in the current refrigeration cycle; the user operation comprises at least one of a refrigerator door opening action, a gear changing action and a forced stopping action.

For example, in order to avoid influence on stability of the reference temperature difference data caused by opening and closing of a door, gear adjustment, and forced shutdown of a user, before the reference temperature difference data is collected each time, it is necessary to determine whether a user operation exists in the refrigeration cycle (i.e., from the end time of the previous refrigeration cycle to the end time of the refrigeration cycle), and if so, the user operation is skipped over the cycle and is not collected. In addition, 3 sets of reference temperature difference data collected cumulatively need to be subjected to error analysis. If the difference between the maximum value and the minimum value in the reference temperature difference exceeds 0.2 ℃, the 1 st group of data is abandoned, and the reference temperature difference at the end moment of the next refrigeration cycle is collected again for re-judgment until all the reference temperature difference data meet the requirement that the error does not exceed the preset temperature difference error (for example, the temperature difference error is 0.2 ℃). The defrosting exit temperature Th is related to the evaporator structure and the assembling manner, and can be determined through experiments, and the present invention is not particularly limited herein. And monitoring the temperature of the evaporator in real time, and when the temperature of the evaporator reaches a preset defrosting exit temperature Th, indicating that the frost layer on the evaporator is completely evaporated at the moment, exiting the defrosting mode and entering a periodic refrigeration process.

It is worth mentioning that in the running process of the refrigerator, whether the evaporator is frost-blocked or not needs to be monitored, if the refrigeration is finished in a mode of the compressor protection shutdown in two continuous periods without opening and closing the door and adjusting the gear, the evaporator is considered to be covered by a frost layer, the heat exchange is poor, and the defrosting needs to be executed immediately. The refrigerator also comprises a timing module which is used for collecting the running time of the whole refrigerator, defrosting is executed after the running time of the whole refrigerator exceeds the set maximum running time tm, tm is determined by a designer through a specific prototype test, and in the embodiment, tm is set to be 120 h.

Further, the refrigerator defrosting control method further includes step S21:

s21, starting with the current refrigeration cycle, and acquiring the temperature difference value of the real-time temperature difference and the initial temperature difference in each refrigeration cycle after at least one continuous refrigeration cycle; then, the step S4 of determining the defrosting requirement of the evaporator according to the temperature difference value between the real-time temperature difference and the initial temperature difference includes steps S41 to S42:

s41, when the temperature difference value corresponding to each refrigeration cycle is larger than or equal to a preset temperature difference threshold value, determining that the defrosting requirement is defrosting;

and S42, when the temperature difference value corresponding to any refrigeration cycle is smaller than a preset temperature difference threshold value, determining that the defrosting requirement is that defrosting is not needed.

For example, a difference between the real-time temperature difference Δ Tn and the initial temperature difference Δ T0 at this time is determined, so as to avoid misdetermination caused by a single sampling error, for example, it is set that when the determination results of D consecutive refrigeration cycles (D being the current refrigeration cycle + passing through at least one consecutive refrigeration cycle) are all greater than a, defrosting is started, for example, D is 3.

Furthermore, in order to further increase the applicability of the scheme under variable working conditions, a self-adaptive adjusting method of the temperature difference threshold value a is added. The temperature difference threshold value a satisfies the following formula:

a＝a0+f(Tan-Ta0)+f(Gn-G0)+f(Fn-F0)；

a0＝f(Ta0,G0,F0)；

wherein a is the temperature difference threshold; a0 is the defrosting temperature difference increment corresponding to the initial temperature difference; ta0 is the environmental temperature of the last refrigeration cycle in the M refrigeration cycles, and Tan is the environmental temperature of the nth refrigeration cycle; g0 is the refrigerator gear of the last refrigerating cycle in the M refrigerating cycles, and Gn is the refrigerator gear of the nth refrigerating cycle; f0 is the compressor speed of the last refrigeration cycle in M refrigeration cycles, Fn is the compressor speed of the nth refrigeration cycle; f (Tan-Ta0) is a correction value corresponding to the change of the environmental temperature; f (Gn-G0) is a correction value corresponding to the gear change; f (Fn-F0) is a correction value corresponding to the change in the compressor rotational speed.

For example, when the initial temperature difference Δ T0 is calculated according to the first 3(M ═ 3) refrigeration cycles, the loop temperature Ta0, the gear G0 and the compressor speed F0 of the last (mth) refrigeration cycle in the first 3 refrigeration cycles are recorded at the same time, and the corresponding defrosting temperature difference increment a0 in this operating condition is calculated, where N ═ 4, M ═ 3 and D ═ 3. Then, at the end of each refrigeration cycle, acquiring a real-time temperature difference Δ Tn, a loop temperature Tan, a gear Gn and a compressor rotation speed Fn, and calculating a defrosting temperature difference increment a, for example, judging whether Δ T4- Δ T0 is greater than or equal to a once in the 4 th refrigeration cycle (at this time, n is 4), and continuously judging whether Δ T5- Δ T0 in the 5 th refrigeration cycle is greater than or equal to a and whether Δ T6- Δ T0 in the 6 th refrigeration cycle is greater than or equal to a because D is 3, if the temperature difference value is greater than or equal to the temperature difference threshold value a in the 4-6 refrigeration cycles, it is indicated that the evaporator has a large frost amount, and defrosting is required. In the process, if the 4 th refrigeration cycle is met and the 5 th refrigeration cycle is not met, the 6 th refrigeration cycle is taken as the current cycle, and whether the corresponding temperature difference values in the D continuous refrigeration cycles are larger than or equal to the temperature difference threshold value or not is calculated again until the temperature difference values corresponding to the D continuous refrigeration cycles are larger than or equal to the temperature difference threshold value, and the defrosting requirement is determined to be defrosting.

Compared with the prior art, the refrigerator defrosting control method disclosed by the embodiment of the invention can establish the corresponding relation between the evaporator frosting amount and the temperature difference between the evaporator and the compartment by utilizing the correlation between the evaporator surface frosting and the reference temperature difference between the evaporator temperature and the compartment temperature of the compressor at the stop time when the refrigerator is in the refrigeration cycle. When the refrigerator is in the shutdown moment of the compressor in the refrigeration cycle, the temperature of the evaporator is detected and compared with the initial temperature difference, the frost amount of the evaporator is indirectly judged according to the comparison result, and defrosting is started timely. Can accurately discern the evaporimeter degree of frosting, open the defrosting heating pipe at better moment and change the frost to the evaporimeter, avoid too early defrosting to cause the energy extravagant, also avoid changing the frost untimely refrigerator refrigeration performance that leads to worsen, realize changing the frost as required in the in-service use process.

While the foregoing is directed to the preferred embodiment of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention.

Claims (10)

1. A refrigerator, characterized by comprising:

the cold air circulating system comprises an evaporator and a fan, the evaporator is arranged between the box body air duct and the inner container, the fan is positioned at the upper part of the evaporator, and the fan transfers the cold energy of the evaporator into the compartment through air circulation;

the controller is configured to:

after the refrigerator is defrosted, respectively acquiring reference temperature differences of the evaporator temperature and the compartment temperature of a compressor at the stop moment in the first M refrigeration cycles of the refrigerator; the first M refrigeration cycles are all refrigeration cycles executed by the refrigerator after defrosting, and the reference temperature differences corresponding to the first M refrigeration cycles are all obtained when a preset temperature difference obtaining condition is met;

calculating an initial temperature difference according to the reference temperature difference;

when the refrigerator is in the Nth refrigeration cycle and the temperature difference obtaining condition is met, obtaining the real-time temperature difference between the evaporator temperature and the compartment temperature of the refrigerator at the stop moment of the compressor in the current refrigeration cycle; wherein N is more than or equal to 4, N is more than M, and N and M are integers;

and determining the defrosting requirement of the evaporator according to the temperature difference value between the real-time temperature difference and the initial temperature difference, and performing defrosting operation on the evaporator when the defrosting requirement meets a preset defrosting condition.

2. The refrigerator of claim 1, wherein the controller is further configured to:

starting with the current refrigeration cycle, and acquiring a temperature difference value between the real-time temperature difference and the initial temperature difference in each refrigeration cycle after at least one continuous refrigeration cycle; then, the determining the defrosting requirement of the evaporator according to the temperature difference value between the real-time temperature difference and the initial temperature difference comprises:

when the temperature difference value corresponding to each refrigeration cycle is greater than or equal to a preset temperature difference threshold value, determining that the defrosting requirement is defrosting;

and when the temperature difference value corresponding to any refrigeration cycle is smaller than a preset temperature difference threshold value, determining that the defrosting requirement is that defrosting is not needed.

3. The refrigerator of claim 1, wherein said calculating an initial temperature difference from said reference temperature difference comprises:

taking the average value of all the reference temperature differences as the initial temperature difference.

4. The refrigerator according to claim 1, wherein the temperature difference obtaining condition is that no user operation is detected in a current cooling cycle; the user operation comprises at least one of a refrigerator door opening action, a gear changing action and a forced stopping action.

5. The refrigerator of claim 1, wherein the controller is further configured to:

acquiring the real-time temperature of the evaporator in the defrosting operation process;

and when the real-time temperature is greater than or equal to a preset defrosting exit temperature, exiting the defrosting mode.

6. A refrigerator defrosting control method is characterized by comprising the following steps:

after the refrigerator is defrosted, respectively acquiring reference temperature differences of the evaporator temperature and the compartment temperature of a compressor at the stop moment in the first M refrigeration cycles of the refrigerator; the first M refrigeration cycles are all refrigeration cycles executed by the refrigerator after defrosting, and the reference temperature differences corresponding to the first M refrigeration cycles are all obtained when a preset temperature difference obtaining condition is met;

calculating an initial temperature difference according to the reference temperature difference;

when the refrigerator is in the Nth refrigeration cycle and the temperature difference obtaining condition is met, obtaining the real-time temperature difference between the evaporator temperature and the compartment temperature of the refrigerator at the stop moment of the compressor in the current refrigeration cycle; wherein N is more than or equal to 4, N is more than M, and N and M are integers;

and determining the defrosting requirement of the evaporator according to the temperature difference value between the real-time temperature difference and the initial temperature difference, and performing defrosting operation on the evaporator when the defrosting requirement meets the preset defrosting condition.

7. The refrigerator defrosting control method of claim 6, wherein the method further comprises:

starting with the current refrigeration cycle, and acquiring a temperature difference value between the real-time temperature difference and the initial temperature difference in each refrigeration cycle after at least one continuous refrigeration cycle; then, the determining the defrosting requirement of the evaporator according to the temperature difference value between the real-time temperature difference and the initial temperature difference comprises:

when the temperature difference value corresponding to each refrigeration cycle is greater than or equal to a preset temperature difference threshold value, determining that the defrosting requirement is defrosting;

and when the temperature difference value corresponding to any refrigeration cycle is smaller than a preset temperature difference threshold value, determining that the defrosting requirement is that defrosting is not needed.

8. The refrigerator defrosting control method of claim 6, wherein the calculating an initial temperature difference according to the reference temperature difference comprises:

taking the average value of all the reference temperature differences as the initial temperature difference.

9. The refrigerator defrosting control method of claim 6, wherein the temperature difference obtaining condition is that no user operation is detected in a current cooling cycle; the user operation comprises at least one of a refrigerator door opening action, a gear changing action and a forced stopping action.

10. The refrigerator defrosting control method of claim 6, wherein the method further comprises:

acquiring the real-time temperature of the evaporator in the defrosting operation process;

and when the real-time temperature is greater than or equal to a preset defrosting exit temperature, exiting the defrosting mode.

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