A method for controlling the speed of a condenser fan and an air-cooled refrigerator

Abstract

This invention discloses a method for controlling the speed of a condenser fan and an air-cooled refrigerator, relating to the field of refrigeration equipment control technology. The method includes: real-time acquisition of exhaust temperature Texhaust and ambient humidity RH, and determination of whether defrosting has ended within 4 hours; dynamic correction of the base temperature threshold T0 based on RH and post-defrosting conditions to obtain the actual threshold T; calculation of the temperature difference ΔT = |Texhaust - T|, determining the speed adjustment step S based on the magnitude of ΔT, with a larger ΔT resulting in a larger S; comparison of Texhaust and T, decreasing the speed when Texhaust < T, increasing the speed when Texhaust > T, and maintaining the speed when Texhaust = T; repeating the above steps for continuous dynamic adjustment. This invention adaptively adjusts the fan speed based on exhaust temperature, ambient humidity, and post-defrosting conditions, improving refrigeration efficiency while ensuring timely evaporation of moisture from the drip tray, avoiding high-temperature damage or water accumulation problems. The control logic is simple, highly adaptable, and applicable to various types of air-cooled refrigeration equipment.

Description

Technical Field

[0001] This invention relates to the field of refrigeration equipment control technology, specifically to a method for controlling the speed of a condenser fan and an air-cooled refrigerator, applicable to various refrigeration systems with condenser fans, such as air-cooled refrigerators. Background Technology

[0002] In typical refrigeration systems of air-cooled refrigerators, a condensate drain pan and evaporator tube are connected between the compressor exhaust and the condenser. The high-temperature gas discharged from the compressor evaporates the condensate produced during defrosting. The condenser fan is a core auxiliary component of the refrigeration system. Its main function is to dissipate heat from the condenser through forced convection, promoting the condensation of the refrigerant from a gaseous state to a liquid state, thereby ensuring the stable and efficient operation of the refrigeration cycle. Its rotational speed directly determines the condenser's heat dissipation efficiency and, consequently, the temperature of the evaporator tube in the drain pan. Currently, existing condenser fan speed control methods mostly use fixed speed control or rely solely on condensing pressure adjustment, which has several drawbacks. On the one hand, when the exhaust temperature of the refrigeration system is too low, if the condenser fan maintains its original speed, the temperature of the exhaust pipe will remain low, preventing the condensate in the drip tray from evaporating in time. Long-term accumulation of condensate can breed bacteria, produce odors, and may even damage equipment components due to overflow, increasing maintenance costs. On the other hand, when the exhaust temperature is too high, a fixed speed or single pressure regulation method cannot quickly improve heat dissipation efficiency, leading to increased condensing pressure in the refrigeration system, decreased refrigeration efficiency, and potentially accelerated compressor valve fatigue and refrigerant oil carbonization due to prolonged high-temperature operation, shortening equipment lifespan. Furthermore, most existing control methods neglect factors affecting the amount of water in the drip tray, such as the higher humidity levels in a high-humidity environment and the larger water volume in the drip tray immediately after defrosting. Summary of the Invention

[0003] The main objective of this invention is to provide a method for controlling the speed of a condenser fan and an air-cooled refrigerator, aiming to solve existing technical problems.

[0004] To achieve the above objectives, the present invention provides a method for controlling the speed of a condenser fan, comprising the following steps: Step 1: Real-time collection of the exhaust temperature T_exhaust and the current ambient humidity RH of the refrigeration system, and determination of whether the refrigeration equipment is within the preset time period after defrosting; Step 2: Based on the collected ambient humidity RH and the post-defrost condition judgment results, dynamically correct the preset basic temperature threshold T0 to obtain the actual temperature threshold T used for judgment. Step 3: Calculate the absolute value of the temperature difference ΔT between the exhaust temperature T_exhaust and the temperature threshold T, which is ΔT = |T_exhaust - T|. Determine the speed adjustment step S based on the magnitude of the absolute value of the temperature difference ΔT, wherein the larger the absolute value of the temperature difference ΔT, the larger the speed adjustment step S. Step 4: Compare the exhaust temperature T_exhaust with the temperature threshold T, and adaptively adjust the condenser fan speed based on the comparison result and the speed adjustment step S. When Tout < T, reduce the speed of the condenser fan according to the speed adjustment step S; When T_out > T, increase the speed of the condenser fan by adjusting the step size S according to the aforementioned speed adjustment; When T_out = T, maintain the current speed of the condenser fan unchanged; Step 5: Repeat steps 1 to 4 to continuously and dynamically adjust the condenser fan speed.

[0005] Furthermore, the preset time period after the defrosting process in step 1 is within 4 hours after the defrosting process ends.

[0006] Furthermore, the dynamic correction of the baseline temperature threshold T0 in step 2 specifically includes: The base temperature threshold T0 is corrected for humidity based on the ambient humidity RH to obtain a first correction threshold T1; Based on the time t at the end of defrosting and the compensation temperature ΔT_defrost(t), the second correction threshold T2 = T1 + ΔT_defrost(t) is obtained; Set the maximum threshold T max If T2 > T max Then T=T max Otherwise, T = T2.

[0007] Furthermore, the method for correcting the base temperature threshold T0 based on the ambient humidity RH is as follows: When RH≤60%RH, T1=T0; When 60%RH < RH ≤ 80%RH, T1 = T0 + (RH - 60) × 0.8℃; When RH > 80%RH, T1 = T0 + 20 + (RH - 80) × 1.2℃.

[0008] Furthermore, the method of superimposing the compensation temperature ΔT_defrost(t) based on the length t at the end of defrosting is as follows: When 0h < t ≤ 1h, ΔT_defrost = 12℃; When 1h < t ≤ 2h, ΔT_defrost = 8℃; When 2h < t ≤ 4h, ΔT_defrost = 5℃; When t > 4h, ΔT_defrost = 0℃.

[0009] Furthermore, the method for determining the speed adjustment step S based on the absolute value of the temperature difference ΔT in step 3 is as follows: Preset speed adjustment step reference value S0; When ΔT≤2℃, S=0.5×S0; When 2℃<ΔT≤5℃, S=1.0×S0; When ΔT > 5℃, S = 1.5 × S0 - 2.0 × S0.

[0010] Furthermore, the minimum value of the speed adjustment step S is not less than 5 r / min, and the maximum value does not exceed 10% of the rated speed of the condenser fan.

[0011] Furthermore, in step 4, after reducing the condenser fan speed, ensure that the condenser fan speed is not lower than the equipment's preset minimum safe speed; after increasing the condenser fan speed, ensure that the condenser fan speed does not exceed the equipment's preset maximum safe speed.

[0012] A refrigerated refrigerator includes a refrigeration system, a condenser fan, a temperature sensor, a humidity sensor, and a controller. The controller controls the rotational speed of the condenser fan using the condenser fan speed control method described above.

[0013] Furthermore, the temperature sensor is installed on the exhaust pipe of the refrigeration system to collect the exhaust temperature T_exhaust; the humidity sensor is installed at the unobstructed front of the refrigerator to collect the ambient humidity RH.

[0014] The beneficial effects of this invention are reflected in: (1) To achieve adaptive adjustment of the condenser fan speed, the speed is dynamically adjusted according to the exhaust temperature. When the exhaust temperature is too high, the speed is increased to improve the cooling efficiency and avoid equipment damage due to high temperature. When the exhaust temperature is too low, the speed is reduced and the residual heat of the exhaust pipe is used to evaporate the water in the water collection pan, reducing the problem of water accumulation, bacterial growth, overflow or freezing damage to the equipment, and reducing maintenance costs.

[0015] (2) Introducing environmental humidity factors and dynamically correcting the temperature threshold T solves the problem of inaccurate adjustment caused by ignoring the influence of humidity in the existing control method. In high humidity environment, the threshold T is increased to ensure that the water in the water tray can evaporate in time; in low humidity environment, the threshold is reasonably set to take into account the cooling efficiency, so that the control method is more in line with the actual operating conditions.

[0016] (3) Added the condition judgment within 4 hours after defrosting, and specifically increased the temperature threshold T, which solved the pain points of excessive water accumulation and slow evaporation in the water tray after defrosting, and prevented water accumulation and freezing and mold growth after defrosting, further improving the reliability of equipment operation, especially suitable for equipment that is prone to defrosting water accumulation such as cold storage and low temperature air conditioning.

[0017] (4) At the same time, the step size of the speed adjustment of the condenser fan can be changed according to the temperature difference between the exhaust temperature and the threshold T, so as to ensure that the speed of the condenser fan can be quickly adjusted to the target speed.

[0018] (5) The control logic is simple and easy to implement. It does not require complex hardware modification and can be directly applied to the control of condenser fans of various existing refrigeration equipment. It has strong adaptability. At the same time, by setting the speed adjustment dead zone, the fan speed fluctuation is reduced, the equipment wear and energy consumption are reduced, and the service life of the equipment is extended.

[0019] (6) Compared with traditional fixed speed or single pressure control methods, this method can keep the refrigeration system in the optimal operating state at all times, which not only ensures refrigeration efficiency, but also realizes the automatic evaporation of water in the drip tray. It is especially suitable for scenarios with large changes in operating conditions and humidity after defrosting (such as the plum rain season in the south and the dry winter environment in the north), taking into account both practicality and economy. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the method for controlling the speed of the condenser fan according to the present invention. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Unless otherwise specified, the embodiments and features in the embodiments of this application can be combined with each other. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] Please see Figure 1 This invention provides a method for controlling the speed of a condenser fan, specifically including: Step 1: Parameter Acquisition and Operating Condition Determination After the air-cooled refrigerator is powered on and running, the controller performs the following operations in real time according to the preset sampling period: The current exhaust temperature Texhaust is collected using an exhaust temperature sensor. For example, under a certain operating condition, the collected exhaust temperature Texhaust = 65℃.

[0023] The ambient humidity (RH) is collected using an ambient humidity sensor. For example, under certain operating conditions, the collected ambient humidity (RH) is 75%.

[0024] The defrosting status signal output by the defrosting controller determines whether the current time is within 4 hours after the defrosting ended. Assuming the time difference between the current time and the last defrosting end time is t=1.5h, since t≤4h, it is determined that the current time is "within 4 hours after the defrosting ended".

[0025] Step 2: Determining the temperature threshold T. Based on the collected ambient humidity (RH) and the results of the defrosting condition judgment, the controller dynamically corrects the preset basic temperature threshold T0 to obtain the actual temperature threshold T used for judgment.

[0026] In this embodiment, the base temperature threshold T0 is preset to the compressor's discharge temperature under normal operating conditions. The compressor's discharge temperature under normal operating conditions refers to the typical discharge temperature of the compressor when the refrigeration system is running stably under standard ambient temperature and humidity conditions. For commonly used air-cooled refrigerator refrigeration systems, the value of T0 is typically between 50℃ and 70℃, preferably 60℃. In this embodiment, T0 = 60℃. The specific correction process is as follows: The ambient humidity correction controller corrects the base temperature threshold T0 for humidity based on the collected ambient humidity RH according to the following piecewise linear correction rule, to obtain the first correction threshold T1: When RH≤60%RH: T1=T0. That is, in a low humidity environment, the ambient humidity does not have a corrective effect on the exhaust temperature threshold, and T1 remains at the base temperature threshold T0.

[0027] When 60%RH < RH ≤ 80%RH: T1 = T0 + (RH 60)×0.8℃. That is, in a moderate humidity environment, the temperature threshold increases linearly with increasing humidity; for every 1% increase in RH, the temperature threshold increases by 0.8℃. For example, when RH=75%RH, T1=60+(75)×0.8℃. 60)×0.8=60+12=72℃.

[0028] When RH > 80%RH: T1 = T0 + 20 + (RH) 80)×1.2℃. That is, in a high humidity environment, the temperature threshold increases further with increasing humidity; for every 1% RH increase in humidity, the temperature threshold increases by 1.2℃. For example, when RH = 90% RH, T1 = 60 + 20 + (90)×1.2℃. 80)×1.2=60+20+12=92℃.

[0029] The above piecewise linear correction rule fully considers the nonlinear influence of the evaporation rate of water in the drip tray in different humidity ranges. In low humidity environments, the air itself is relatively dry, and the evaporation rate of water in the drip tray is fast, so there is no need to increase the temperature threshold. In medium humidity environments, the air humidity is moderate, and the evaporation rate of water decreases, so the temperature threshold needs to be appropriately increased to enhance the evaporation effect. In high humidity environments, the air is close to saturation, and the evaporation rate of water decreases significantly, so the temperature threshold needs to be greatly increased to ensure that the water in the drip tray can evaporate in time.

[0030] The defrost time decay compensation controller determines whether the refrigeration system is within 4 hours of defrosting completion. If it is, the compensation temperature ΔT_defrost(t) is added based on the defrosting time t at the end of the defrost process. If it is not within 4 hours of defrosting completion, ΔT_defrost(t) = 0. The specific compensation rules are as follows: When 0h < t ≤ 1h: ΔT_defrost = 12℃. Within 1 hour immediately after defrosting, the water collection tray has the most water and the need for evaporation is the most urgent. Therefore, the maximum compensation temperature of 12℃ is given to ensure that the large amount of water can evaporate quickly.

[0031] When 1h < t ≤ 2h: ΔT_defrost = 8℃. In the first 1-2 hours after defrosting, some of the water in the drip tray has evaporated, but a higher temperature threshold is still needed to maintain the evaporation rate, so the compensation temperature is reduced to 8℃.

[0032] When 2h < t ≤ 4h: ΔT_defrost = 5℃. In the 2nd to 4th hour after defrosting, most of the water in the drip tray has evaporated, reducing the evaporation demand and further lowering the compensation temperature to 5℃.

[0033] When t > 4h: ΔT_defrost = 0℃. More than 4 hours after defrosting ends, the water in the drip tray has usually completely or almost completely evaporated, requiring no further compensation.

[0034] Continuing with the example above, the defrost ends at a time t=1.5h, which falls within the range of 1h<t≤2h, therefore ΔT_defrost=8℃.

[0035] Threshold calculation and the limiter controller calculate the second corrected threshold T2 = T1 + ΔT_defrost (t). Continuing the example above, T1 = 72℃, ΔT_defrost = 8℃, therefore T2 = 72 + 8 = 80℃.

[0036] The controller further sets the maximum temperature threshold T. max=T0+25℃. The maximum temperature threshold is set to prevent the condenser fan from operating at high speed for extended periods due to excessively high temperatures, thus avoiding unnecessary energy consumption and fan wear. In this embodiment, T... max =60+25=85℃.

[0037] The controller will connect T2 and T max Comparison: If T2 > T max Then T=T max Otherwise, T = T2. Continuing with the example above, T2 = 80℃ < T max =85℃, therefore T=80℃.

[0038] Through the above dual correction, the temperature threshold T can adapt to the needs of different humidity environments and also be suitable for the working conditions after defrosting, avoiding the problem of water not evaporating in time in high humidity environments and after defrosting, while also taking into account the cooling efficiency in low humidity environments.

[0039] Step 3: Determine the speed adjustment step rule. The controller presets the speed adjustment step reference value S0, which is determined according to the model, rated speed and speed range of the condenser fan.

[0040] For condenser fans using stepless speed regulation, the step reference value S0 can be set to 50 r / min-100 r / min, preferably 50 r / min. The stepless speed regulation fan can continuously adjust its speed via a PWM signal; when the step reference value is set to 50 r / min, smooth speed regulation can be achieved.

[0041] For condenser fans that use graded speed regulation, a corresponding reference step can be set according to the speed level. For example, if the fan has 10 speed levels and the rated speed is 2000 r / min, then the speed interval of each level is 200 r / min, and the reference value S0 of the step can be set to 200 r / min.

[0042] In this embodiment, the condenser fan adopts a stepless speed-regulating brushless DC motor with a rated speed of 2500 r / min and a step reference value S0 = 50 r / min.

[0043] The controller calculates the absolute value of the temperature difference between the exhaust temperature T_exhaust and the actual judgment threshold T, ΔT = |T_exhaustT|. Continuing the example above, T_exhaust = 65℃, T = 80℃, therefore ΔT = |6580| = 15℃.

[0044] The controller determines the speed adjustment step S according to the absolute value of the temperature difference ΔT, following these rules: When ΔT ≤ 2℃: S = 0.5 × S0. At this point, the exhaust temperature is close to the threshold, and only a small adjustment of the engine speed is needed to avoid excessive speed fluctuations that could cause system oscillations. For example, S = 0.5 × 50 = 25 r / min.

[0045] When 2℃ < ΔT ≤ 5℃: ​​S = 1.0 × S0. At this point, there is a certain difference between the exhaust temperature and the threshold temperature. A conventional step adjustment is used to balance response speed and stability. For example, S = 1.0 × 50 = 50 r / min.

[0046] When ΔT > 5℃: S = 1.5 × S0 - 2.0 × S0. At this point, the exhaust temperature differs significantly from the threshold, requiring a substantial adjustment of the engine speed to ensure rapid approach to the target speed and improve response efficiency. The specific value can be determined by linear interpolation within the range of 1.5 × S0 - 2.0 × S0 based on the temperature difference; the larger the temperature difference, the larger the step size. For example, when ΔT = 15℃, S can be taken as 2.0 × 50 = 100 r / min.

[0047] Continuing with the example above, ΔT = 15℃ > 5℃, therefore S = 2.0 × 50 = 100 r / min.

[0048] Meanwhile, the controller sets upper and lower limits for the adjustment step: the minimum adjustment step is not less than 5 r / min, and the maximum adjustment step does not exceed 10% of the rated speed of the condenser fan. In this embodiment, the rated speed is 2500 r / min, the maximum adjustment step does not exceed 250 r / min, and S=100 r / min is within the safe range.

[0049] Step 4: The speed control controller based on exhaust temperature and step size rules compares the real-time collected exhaust temperature T_exhaust with the corrected temperature threshold T, and, combined with the speed adjustment step size S determined in Step 3, adaptively adjusts the condenser fan speed. The specific adjustment rules are as follows: When the exhaust temperature T_exhaust is less than the temperature threshold T, the controller determines that the exhaust temperature is too low and reduces the speed of the condenser fan by the determined adjustment step S.

[0050] Continuing the example above, Toutlet = 65℃, T = 80℃, and Toutlet < T. Therefore, the controller reduces the speed of the condenser fan by S = 100 r / min. Assuming the current condenser fan speed is 1800 r / min, the reduced speed will be 1700 r / min.

[0051] Reducing the rotation speed decreases the condenser's heat dissipation efficiency, slightly increasing the condensing pressure of the refrigeration system, which in turn raises the temperature of the exhaust pipe. This increased exhaust pipe temperature raises the temperature of the high-temperature gas flowing through the evaporator tubes of the drip tray, enabling more effective evaporation of moisture from the drip tray and preventing water accumulation, freezing, or mold growth.

[0052] When reducing the speed, the controller must ensure that the condenser fan speed does not fall below the equipment's preset minimum safe speed to prevent the fan from stopping or malfunctioning. The minimum safe speed setting needs to be determined based on the fan model, and is generally not lower than 20% of the rated speed. In this embodiment, the rated speed is 2500 r / min, and the minimum safe speed is 500 r / min. The currently reduced speed is 1700 r / min, which is greater than 500 r / min, thus meeting the safety requirements.

[0053] When the exhaust temperature T_exhaust > temperature threshold T, the controller determines that the exhaust temperature is too high, and at this time, the speed of the condenser fan is increased by the determined adjustment step S.

[0054] For example, under another operating condition, the collected exhaust temperature T_exhaust = 95℃, the ambient humidity RH = 55%RH, and the defrosting duration t = 5 hours. Then T1 = T0 = 60℃, ΔT_defrost = 0℃, and T = 60℃. ΔT = |9560| = 35℃ > 5℃, S = 2.0 × 50 = 100 r / min. T_exhaust > T, therefore the controller increases the speed of the condenser fan by 100 r / min.

[0055] Increasing the rotation speed improves the condenser's heat dissipation efficiency, which can quickly reduce the condensing pressure of the refrigeration system, reduce the residence time of the refrigerant in the condenser, and thus improve the refrigeration cycle efficiency, avoiding equipment damage problems such as compressor valve plate fatigue and refrigeration oil carbonization caused by excessively high exhaust temperature.

[0056] When increasing the speed, the controller must ensure that the condenser fan speed does not exceed the equipment's preset maximum safe speed to prevent fan overload. The maximum safe speed generally does not exceed 110% of the rated speed. In this embodiment, the rated speed is 2500 r / min, and the maximum safe speed is 2750 r / min.

[0057] When the exhaust temperature T_exhaust equals the temperature threshold T, the controller determines that the exhaust temperature is equal to the threshold and maintains the current speed of the condenser fan unchanged to ensure that the refrigeration system is in a stable operating state. At this time, it indicates that the current operating state of the refrigeration system has reached equilibrium, and no speed adjustment is required.

[0058] Step 5: The continuous dynamic adjustment controller repeats steps 1 to 4 according to the preset sampling cycle, collects exhaust temperature T_exhaust and ambient humidity RH in real time, determines the post-defrost operating conditions in real time, dynamically corrects the temperature threshold T, calculates the temperature difference ΔT in real time and adjusts the step size S, and continuously adjusts the condenser fan speed according to the comparison results of exhaust temperature and threshold and the step size rules.

[0059] Through continuous dynamic adjustment, the refrigeration system can balance the needs of refrigeration efficiency, water evaporation in the drip tray, safe operation of equipment, and rapid speed adjustment under different operating conditions, ambient humidity, and after defrosting, thus achieving dynamic balance of the refrigeration system.

[0060] This invention also provides a frost-free refrigerator. The refrigeration system of the frost-free refrigerator includes a compressor, a condenser, a throttling device, an evaporator, and refrigerant piping connecting the above components. A condenser fan is located on one side of the condenser and is used to dissipate heat from the condenser through forced convection. A water-receiving evaporator pipe is provided on the exhaust pipe between the compressor's exhaust port and the condenser. This water-receiving evaporator pipe is placed in a water-receiving pan and is used to evaporate the condensate produced during defrosting of the frost-free refrigerator by the high-temperature gas discharged from the compressor.

[0061] To implement the control method of this invention, the air-cooled refrigerator is also equipped with the following hardware: Exhaust Temperature Sensor: A temperature sensor is installed on the exhaust pipe of the refrigeration system to collect the exhaust temperature T_exhaust in real time. This temperature sensor is preferably a PT100 platinum resistance temperature sensor or an NTC thermistor temperature sensor. The PT100 sensor has the advantages of high measurement accuracy and good stability, making it suitable for applications requiring high temperature measurement accuracy; the NTC thermistor sensor has the advantages of fast response speed and lower cost, making it suitable for cost-sensitive mass production applications.

[0062] The specific installation location for the temperature sensor is either the pipe section between the compressor exhaust port and the evaporator tube of the drip tray, or the pipe section between the evaporator tube of the drip tray and the condenser. During installation, ensure that the temperature sensor's probe is in close contact with the outer wall of the exhaust pipe, and apply thermal grease to the contact area to reduce thermal resistance and improve the accuracy and response speed of temperature measurement. The temperature sensor is electrically connected to the controller of the air-cooled refrigerator via a signal line, transmitting the collected exhaust temperature signal to the controller in real time.

[0063] Ambient humidity sensor: An ambient humidity sensor is installed at an unobstructed location on the front of the refrigerator to collect real-time ambient humidity (RH). The ambient humidity sensor is preferably a capacitive or resistive humidity sensor, with a preferred measurement range of 0%RH-100%RH and a preferred measurement accuracy of ±3%RH.

[0064] The humidity sensor should be installed on the upper part or side of the front panel of the refrigerator, avoiding locations such as the refrigerator's air vents and condenser vents that may be affected by localized temperature and humidity interference. This ensures that the collected humidity data accurately reflects the humidity conditions of the environment in which the refrigerator is located. The humidity sensor is electrically connected to the controller via a signal cable, transmitting the collected ambient humidity signal to the controller in real time.

[0065] Defrosting Status Monitoring: Frost-free refrigerators typically come with a defrost sensor and a defrost controller. The defrost sensor is usually located on the evaporator surface to detect the degree of frost buildup. When the evaporator surface temperature is below the preset defrost start temperature threshold, the defrost controller activates the defrost heater to defrost; when the evaporator surface temperature rises to the preset defrost end temperature threshold, the defrost controller stops defrosting.

[0066] In this invention, the determination of defrosting completion is obtained through the defrosting sensor or controller output signal integrated into the refrigeration system. Specifically, the controller receives the defrosting status signal from the defrosting controller in real time. When the defrosting status signal switches from "defrosting in progress" to "defrosting completed," the controller records the current time as the defrosting completion time and starts timing. If the time difference between the current time and the defrosting completion time is ≤4h, it is determined to be "within 4h after defrosting ended"; if the time difference is >4h, it is determined to be "not within 4h after defrosting ended."

[0067] Controller: The controller is the core execution unit of the control method of this invention, preferably a microcontroller or digital signal processor. The controller integrates a memory to store preset control parameters such as the base temperature threshold T0, the speed adjustment step reference value S0, the maximum temperature threshold Tmax, the minimum safe speed, and the maximum safe speed. The controller also integrates a timer to record the duration t after defrosting ends.

[0068] The controller is connected to the exhaust temperature sensor, ambient humidity sensor, and defrost controller via signal lines, receiving exhaust temperature signals, ambient humidity signals, and defrost status signals transmitted by these components. The controller is electrically connected to the condenser fan motor via a drive circuit, controlling the condenser fan speed by outputting a PWM signal or voltage signal. For condenser fans using brushless DC motors, the controller can achieve stepless speed regulation by adjusting the duty cycle of the PWM signal; for condenser fans using AC asynchronous motors, the controller can achieve graded speed regulation by adjusting the output voltage or frequency.

[0069] Example 1: Control process under high temperature and high humidity environment Assume a frost-free refrigerator is operating in southern China during the rainy season, with an ambient temperature of 30℃ and an ambient humidity of RH = 88%RH. The refrigerator has just completed one defrosting cycle, which lasted for t = 0.5 hours. The current exhaust temperature T_exhaust = 68℃, and the current condenser fan speed is 1500 r / min.

[0070] The controller operates according to the following steps: Step 1: Collect data at T_outlet = 68℃, RH = 88%RH, t = 0.5h ≤ 4h, and determine it as "within 4 hours after defrosting ends".

[0071] Step 2: Determining the temperature threshold T. Humidity correction: RH = 88%RH > 80%RH, T1 = T0 + 20 + (8880) × 1.2℃. Assuming T0 = 60℃, then T1 = 60 + 20 + 9.6 = 89.6℃. Defrosting compensation: t = 0.5h is in the interval 0h < t ≤ 1h, ΔT_defrost = 12℃. T2 = T1 + ΔT_defrost = 89.6 + 12 = 101.6℃. Limiting: Tmax = T0 + 25 = 85℃, T2 = 101.6℃ > 85℃, therefore T = 85℃.

[0072] Step 3: ΔT = |T_displacementT| = |6885| = 17℃ > 5℃, S = 2.0 × 50 = 100 r / min.

[0073] Step 4: T_exhaust = 68℃ < T = 85℃, reduce the speed by S = 100r / min. After reduction, the speed is 1500 × 100 = 1400r / min, which is higher than the minimum safe speed of 500r / min.

[0074] Step 5: Continuous dynamic adjustment. Under harsh operating conditions of high temperature and humidity and just after defrosting, this embodiment significantly increases the temperature threshold T to 85°C, so that the exhaust temperature of 68°C is much lower than the threshold of 85°C. The controller controls the condenser fan to reduce its speed, and uses the residual heat of the exhaust pipe to fully evaporate the large amount of water accumulated in the water tray, effectively avoiding the problem of bacteria growth and odor caused by water accumulation in the water tray under high humidity conditions.

[0075] Example 2: Control process under low temperature and low humidity environment Assume the same air-cooled refrigerator is operating in a northern winter environment with an ambient temperature of 10℃ and an RH of 30%. The refrigerator is not within 4 hours of defrosting. The current exhaust temperature T_exhaust = 72℃, and the current condenser fan speed is 2000 r / min. The controller operates according to the following steps: Step 1: Collect data at T_outlet = 72℃, RH = 30%RH, t = 6h > 4h, and determine it as "within 4 hours after defrosting ends".

[0076] Step 2: Determining the temperature threshold T. Humidity correction: RH = 30%RH ≤ 60%RH, T1 = T0 = 60℃. Defrost compensation: t = 6h > 4h, ΔT_defrost = 0℃. T2 = T1 + 0 = 60℃. Limitation: T2 = 60℃ < Tmax = 85℃, therefore T = 60℃.

[0077] Step 3: ΔT = |T_displacementT| = |7260| = 12℃ > 5℃, S = 2.0 × 50 = 100 r / min.

[0078] Step 4: T_exhaust = 72℃ > T = 60℃, increase the rotation speed by S = 100 r / min. The increased rotation speed is 2000 + 100 = 2100 r / min, which is lower than the maximum safe rotation speed of 2750 r / min.

[0079] Step 5: Continuous dynamic adjustment. In a low-temperature and low-humidity environment, the temperature threshold T in this embodiment is maintained at the base value of 60℃. The exhaust temperature of 72℃ is higher than the threshold of 60℃. The controller controls the condenser fan to increase its speed, enhance the condenser's heat dissipation efficiency, and improve the refrigeration cycle efficiency. At the same time, in a low-humidity environment, the water evaporation demand of the drip tray is low, so there is no need to deliberately reduce the speed to increase the exhaust temperature, thus maximizing the refrigeration efficiency.

[0080] Example 3: Control process under moderate humidity and non-defrost conditions Assume the air-cooled refrigerator is operating under normal conditions: ambient temperature 25℃, ambient humidity RH = 70%RH. The refrigerator is not within 4 hours of defrosting. The current exhaust temperature T_exhaust = 62℃, and the current condenser fan speed is 1800 r / min. The controller operates according to the following steps: Step 1: Collect data at T_outlet = 62℃, RH = 70%RH, t = 8h > 4h, and determine it as "within 4 hours after defrosting ends".

[0081] Step 2: Determining the temperature threshold T. Humidity correction: 60%RH < RH = 70%RH ≤ 80%RH, T1 = T0 + (7060) × 0.8℃ = 60 + 8 = 68℃. Defrost compensation: t = 8h > 4h, ΔT_defrost = 0℃. T2 = 68 + 0 = 68℃. Limitation: T2 = 68℃ < Tmax = 85℃, therefore T = 68℃.

[0082] Step 3: ΔT = |T_displacedT| = |6268| = 6℃ > 5℃, S = 2.0 × 50 = 100 r / min.

[0083] Step 4: T_exhaust = 62℃ < T = 68℃, reduce the speed by S = 100r / min. After reduction, the speed is 1800 × 100 = 1700r / min, which is higher than the minimum safe speed of 500r / min.

[0084] Step 5: Continuous dynamic adjustment. In a moderate humidity environment, the temperature threshold T in this embodiment is moderately increased to 68°C, so that the exhaust temperature of 62°C is slightly lower than the threshold of 68°C. The controller controls the condenser fan to slightly reduce its speed. While ensuring cooling efficiency, the waste heat of the exhaust pipe is used to appropriately evaporate the small amount of water in the water collection pan, thus achieving a good balance between cooling efficiency and water evaporation.

[0085] Example 4: Fine-tuning process when the temperature difference is small Assume the air-cooled refrigerator is operating stably under stable conditions, with an ambient temperature of 25℃ and an ambient humidity of RH = 60%RH. The refrigerator is not within 4 hours of defrosting. The current exhaust temperature T_exhaust = 61℃, and the current condenser fan speed is 1600 r / min. The controller operates according to the following steps: Step 1: Collect data at T_out = 61℃, RH = 60%RH, t > 4h.

[0086] Step 2: Humidity correction: RH=60%RH≤60%RH, T1=T0=60℃. Defrosting compensation is 0. T=60℃.

[0087] Step 3: ΔT = |T_displacedT| = |6160| = 1℃ ≤ 2℃, S = 0.5 × 50 = 25 r / min.

[0088] Step 4: T_discharge = 61℃ > T = 60℃, increase the rotation speed by S = 25 r / min. The increased rotation speed is 1600 + 25 = 1625 r / min.

[0089] Step 5: Continuous dynamic adjustment. When the difference between the exhaust temperature and the threshold temperature is small, this embodiment uses a small adjustment step of S=25r / min for fine adjustment, avoiding system oscillation and equipment wear caused by large fluctuations in speed, and ensuring the stable operation of the refrigeration system.

[0090] Variations in temperature threshold correction methods: In the above embodiments, the ambient humidity correction uses a piecewise linear correction method. Alternatively, the ambient humidity correction can also use a continuous function correction method, for example: T1 = T0 + α × (RHRH0) where RH0 is the reference humidity and α is the humidity correction factor. When RH < RH0, T1 < T0; when RH > RH0, T1 > T0. Alternatively, the environmental humidity correction can also be performed using a lookup table. That is, a table showing the correspondence between environmental humidity and temperature threshold correction values ​​is pre-stored in the controller's memory, and the controller directly looks up the corresponding correction value based on the collected environmental humidity.

[0091] Variations in the post-defrost compensation method: In the above embodiments, the post-defrost compensation temperature ΔT_defrost(t) adopts a piecewise constant method. Alternatively, the post-defrost compensation temperature can also adopt a continuously decaying function method, for example: ΔT_defrost(t) = ΔT0 × e^(λt), where ΔT0 is the initial compensation temperature immediately after defrosting, λ is the decay coefficient, and t is the duration after defrosting ends. This method achieves a smooth decay of the compensation temperature, allowing for more precise control. Alternatively, the post-defrost compensation temperature can also adopt a linear decay method, for example: ΔT_defrost(t) = ΔT0 × (1t / 4), where 0 < t ≤ 4h. In this method, the compensation temperature decreases linearly with time, reaching its maximum at t = 0 and decreasing to 0 at t = 4h.

[0092] Variations in step size determination: In the above embodiment, the speed adjustment step size S is determined based on the segmented intervals of the temperature difference ΔT. Alternatively, the speed adjustment step size S can also be determined proportionally to the temperature difference ΔT, for example: S = K × ΔT, where K is the proportionality coefficient and ΔT is the absolute value of the temperature difference. This method allows the step size to change continuously with the temperature difference, resulting in smoother control. Alternatively, the speed adjustment step size S can also be determined using PID control, that is, by comprehensively considering the current temperature difference, the rate of change of the temperature difference, and the cumulative value of the temperature difference to determine the optimal speed adjustment step size, achieving more precise control.

[0093] Variations in the sampling period: In the above embodiments, the preferred sampling period of the controller is 5 seconds. Alternatively, the sampling period can be adjusted within the range of 1 to 60 seconds according to actual needs. For applications requiring high control response speed, a shorter sampling period can be used; for applications requiring high control stability, a longer sampling period can be used.

[0094] Variation Example 5: Applicable to other refrigeration equipment The above embodiments use a frost-free refrigerator as an example for illustration, but the control method of the present invention is also applicable to various refrigeration equipment with condenser fans and defrosting functions, such as cold storage, low-temperature air conditioners, and display cases. For different types of refrigeration equipment, the base temperature threshold T0, step reference value S0, and maximum temperature threshold T can be adaptively adjusted according to the specific operating conditions and design parameters of the equipment. max The same control effect can be achieved by adjusting control parameters such as minimum safe speed and maximum safe speed.

[0095] The following comparative experimental data further illustrates the beneficial effects of the technical solution of the present invention.

[0096] (I) Comparison of Water Evaporation Effect in the Drip Tray: Under the same conditions of ambient temperature 25℃ and ambient humidity 80%RH, two identical air-cooled refrigerators were compared using the traditional fixed speed control method and the control method of this invention, respectively. After defrosting, the initial water volume in the drip tray was 200mL in both cases.

[0097] In refrigerators using the traditional fixed-speed control method, the condenser fan always operates at its rated speed, and the exhaust pipe temperature is maintained between 58℃ and 62℃. Four hours after defrosting, approximately 45mL of water remains in the drip tray, representing an evaporation rate of approximately 77.5%.

[0098] In a refrigerator using the control method of this invention, within 0-1 hour after defrosting, the temperature threshold T rises to a relatively high level, the controller reduces the speed of the condenser fan, and the exhaust pipe temperature rises to 75℃-80℃. Within 1-2 hours after defrosting, the temperature threshold T gradually decreases, and the exhaust pipe temperature remains at 70℃-75℃. Within 2-4 hours after defrosting, the temperature threshold T further decreases, and the exhaust pipe temperature remains at 65℃-70℃. Four hours after defrosting, approximately 8 mL of water remains in the drip tray, with a water evaporation rate of approximately 96%. Therefore, the control method of this invention significantly improves the water evaporation efficiency of the drip tray after defrosting.

[0099] (II) Comparison of Refrigeration Efficiency Under high temperature conditions of 35°C, two air-cooled refrigerators of the same model were compared and tested using the traditional fixed speed control method and the control method of the present invention, respectively.

[0100] In a refrigerator using the traditional fixed-speed control method, the condenser fan always maintains its rated speed, the condensing pressure of the refrigeration system is stable at 1.8MPa, the compressor exhaust temperature is stable at 95℃, and the time required for the freezer compartment to cool down to 18℃ is 120 minutes.

[0101] In a refrigerator employing the control method of this invention, the controller dynamically adjusts the condenser fan speed based on the relationship between exhaust temperature and a threshold. When the exhaust temperature rises, the controller increases the fan speed to enhance heat dissipation; when the exhaust temperature decreases, the controller decreases the fan speed to reduce heat dissipation. Throughout the entire operation, the condensing pressure remains stable at 1.5MPa-1.7MPa, the compressor exhaust temperature remains stable at 85℃-90℃, and the time required for the freezer compartment to cool to 18℃ is 105 minutes. It is evident that the control method of this invention can effectively reduce condensing pressure and exhaust temperature under high-temperature conditions, improving refrigeration efficiency by approximately 12.5%.

[0102] The comparative experiments above show that the control method of the present invention, by dynamically adjusting the speed of the condenser fan, avoids problems such as compressor valve plate fatigue and refrigerant oil carbonization caused by excessively high exhaust temperature, and avoids problems such as water accumulation and freezing in the drip tray caused by excessively low exhaust temperature. This effectively extends the service life of the refrigeration equipment and reduces maintenance costs.

[0103] It is understood that the systems, devices, and storage media provided in the embodiments of the present invention correspond to the methods provided in the embodiments of the present invention, and the explanations, examples, and beneficial effects of the relevant content can be referred to the corresponding parts of the above methods.

[0104] In the above embodiments, implementation can be achieved entirely or partially through software, hardware, firmware, or any combination thereof. When implemented using software, it can be implemented entirely or partially as a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, all or part of the processes or functions described in the embodiments of this application are generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, the computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired (e.g., coaxial cable, fiber optic, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium can be any available medium that a computer can access or a data storage device such as a server or data center that integrates one or more available media. The available medium can be a magnetic medium (e.g., floppy disk, hard disk, magnetic tape), an optical medium (e.g., DVD), or a semiconductor medium (e.g., solid state disk (SSD)).

[0105] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0106] The various embodiments in this specification are described in a related manner. Similar or identical parts between embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, the system embodiments are basically similar to the method embodiments, so the description is relatively simple; relevant parts can be referred to the descriptions of the method embodiments.

[0107] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for controlling the speed of a condenser fan, characterized in that, Includes the following steps: Step 1: Real-time collection of the exhaust temperature T_exhaust and the current ambient humidity RH of the refrigeration system, and determination of whether the refrigeration equipment is within the preset time period after defrosting; Step 2: Based on the collected ambient humidity RH and the post-defrost condition judgment results, dynamically correct the preset basic temperature threshold T0 to obtain the actual temperature threshold T used for judgment. Step 3: Calculate the absolute value of the temperature difference ΔT between the exhaust temperature T_exhaust and the temperature threshold T, which is ΔT = |T_exhaust - T|. Determine the speed adjustment step S based on the magnitude of the absolute value of the temperature difference ΔT, wherein the larger the absolute value of the temperature difference ΔT, the larger the speed adjustment step S. Step 4: Compare the exhaust temperature T_exhaust with the temperature threshold T, and adaptively adjust the condenser fan speed based on the comparison result and the speed adjustment step S. When Tout < T, reduce the speed of the condenser fan according to the speed adjustment step S; When T_out > T, increase the speed of the condenser fan by adjusting the step size S according to the aforementioned speed adjustment; When T_out = T, maintain the current speed of the condenser fan unchanged; Step 5: Repeat steps 1 to 4 to continuously and dynamically adjust the condenser fan speed.

2. The method for controlling the speed of a condenser fan according to claim 1, characterized in that: The preset time period after the defrosting process in step 1 is within 4 hours after the defrosting process ends.

3. The method for controlling the speed of a condenser fan according to claim 1, characterized in that: The dynamic correction of the baseline temperature threshold T0 in step 2 specifically includes: The base temperature threshold T0 is corrected for humidity based on the ambient humidity RH to obtain a first correction threshold T1; Based on the time t at the end of defrosting and the compensation temperature ΔT_defrost(t), the second correction threshold T2 = T1 + ΔT_defrost(t) is obtained; Set the maximum threshold T max If T2 > T max Then T=T max Otherwise, T = T2.

4. The method for controlling the speed of a condenser fan according to claim 3, characterized in that: The method for correcting the base temperature threshold T0 based on ambient humidity (RH) is as follows: When RH≤60%RH, T1=T0; When 60%RH < RH ≤ 80%RH, T1 = T0 + (RH - 60) × 0.8℃; When RH > 80%RH, T1 = T0 + 20 + (RH - 80) × 1.2℃.

5. The method for controlling the speed of a condenser fan according to claim 3, characterized in that: The method of superimposing the compensation temperature ΔT_defrost(t) based on the length t at the end of defrosting is as follows: When 0h < t ≤ 1h, ΔT_defrost = 12℃; When 1h < t ≤ 2h, ΔT_defrost = 8℃; When 2h < t ≤ 4h, ΔT_defrost = 5℃; When t > 4h, ΔT_defrost = 0℃.

6. The method for controlling the speed of a condenser fan according to claim 1, characterized in that: The method for determining the speed adjustment step S based on the absolute value of the temperature difference ΔT in step 3 is as follows: Preset speed adjustment step reference value S0; When ΔT≤2℃, S=0.5×S0; When 2℃<ΔT≤5℃, S=1.0×S0; When ΔT > 5℃, S = 1.5 × S0 - 2.0 × S0.

7. The method for controlling the speed of a condenser fan according to claim 6, characterized in that: The minimum value of the speed adjustment step S is not less than 5 r / min, and the maximum value does not exceed 10% of the rated speed of the condenser fan.

8. The method for controlling the speed of a condenser fan according to claim 1, characterized in that: In step 4, after reducing the condenser fan speed, ensure that the condenser fan speed is not lower than the equipment's preset minimum safe speed; after increasing the condenser fan speed, ensure that the condenser fan speed does not exceed the equipment's preset maximum safe speed.

9. A refrigerated refrigerator, comprising a refrigeration system, a condenser fan, a temperature sensor, a humidity sensor, and a controller, characterized in that, The controller uses the condenser fan speed control method as described in any one of claims 1 to 8 to control the speed of the condenser fan.

10. The air-cooled refrigerator according to claim 9, characterized in that: The temperature sensor is installed on the exhaust pipe of the refrigeration system to collect the exhaust temperature T_exhaust; the humidity sensor is installed at the unobstructed front of the refrigerator to collect the ambient humidity RH.

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