A control method of a variable frequency fan of a refrigerator

Abstract

The application discloses a control method of a variable frequency fan of a refrigerator, the fan is used for promoting the release of cold quantity of an evaporator of the refrigerator, and the rotating speed of the fan is controlled according to the temperature difference between the inlet and outlet of the evaporator. In the prior art, the gear of the fan corresponds to the gear of the compressor one by one, and only the relatively optimal matching effect in each temperature interval can be achieved. The rotating speed of the fan is controlled according to the temperature difference between the inlet and outlet of the evaporator in the application, the temperature difference between the inlet and outlet of the evaporator reflects the state of the refrigerant in the evaporator, that is, the cold quantity output of the evaporator is controlled according to the state of the refrigerant in the evaporator, and undoubtedly the evaporator can maintain the optimal heat exchange effect under various ambient temperatures.

Description

Technical Field

[0001] This invention relates to household refrigerators, specifically a method for controlling a refrigerator's inverter fan. Background Technology

[0002] In existing technologies, the control rules for fans in variable frequency refrigerator control systems are based on the compressor frequency or the same control rules used for the compressor to control the fan speed. The fan speed corresponds one-to-one with the compressor speed. This control method cannot achieve an optimal matching effect for the heat exchange efficiency of the evaporator under different ambient temperatures.

[0003] The fan described in this invention is installed above the evaporator to facilitate the release of cold energy from the evaporator into the chamber. The speed of the fan affects the heat exchange efficiency of the evaporator. Summary of the Invention

[0004] To avoid the shortcomings of the existing technology, the purpose of this invention is to provide a control method for a refrigerator inverter fan, so that the heat exchange efficiency of the evaporator can achieve the optimal matching effect under different ambient temperatures.

[0005] The objective of this invention is achieved through the following technical solution: a control method for a refrigerator inverter fan, wherein the fan is used to promote the release of cold energy from the refrigerator evaporator, characterized in that the fan speed is controlled according to the temperature difference between the inlet and outlet of the evaporator.

[0006] The temperature difference between the evaporator inlet and outlet reflects the state of the refrigerant inside the evaporator. This invention directly controls the cooling output of the evaporator based on the state of the refrigerant inside the evaporator (achieved by controlling the fan speed), which undoubtedly enables the evaporator to maintain the best heat exchange effect under various ambient temperatures.

[0007] If the refrigerator compressor stops when the fan runs continuously at the same speed for a specified period of time, the fan is then controlled to run at a lower speed. This step can avoid frequent short-term starts of the compressor and help extend the compressor's lifespan.

[0008] The control method further includes the following step: controlling the fan speed according to the condensing pressure of the refrigerator's condenser.

[0009] The condensing pressure reflects the refrigerant flow rate. An increase in condensing pressure leads to a greater refrigerant flow rate into the evaporator, which in turn requires a corresponding increase in fan speed; conversely, a decrease in condensing pressure results in a decrease in fan speed. This invention adds this step to enable a more rapid response to changes in ambient temperature, internal temperature, etc. (these changes are more sensitively reflected in the condensing pressure).

[0010] When the compressor is powered on for the first time, control the fan to run at its maximum speed.

[0011] The specific method for controlling the fan speed based on the temperature difference between the evaporator inlet and outlet is as follows:

[0012] The evaporator inlet temperature is T1, the evaporator outlet temperature is T2, and the temperature difference between the two is ΔT = T2 - T1. Determine whether ΔT is less than the first preset value A. If so, increase the fan speed by 1 level.

[0013] Determine if ΔT is greater than the second preset value B. If so, reduce the fan speed by 1 level.

[0014] B is greater than A. Thresholds A and B are used to control the state of the refrigerant in the evaporator to prevent the refrigerant from evaporating incompletely or turning into a superheated gaseous state.

[0015] The specific method for controlling the fan speed based on the condensing pressure of the refrigerator's condenser is as follows:

[0016] Determine if P is less than the third preset value C. If so, reduce the fan speed by 1 level.

[0017] Determine if P is greater than the fourth preset value D. If so, increase the fan speed by 1 level.

[0018] D is greater than C.

[0019] Beneficial effects:

[0020] 1) In the prior art, the fan speed and the compressor speed correspond one-to-one, which can only achieve a better matching effect in various temperature ranges. The present invention controls the fan speed by the temperature difference between the inlet and outlet of the evaporator. The temperature difference between the inlet and outlet of the evaporator reflects the state of the refrigerant in the evaporator. That is, the present invention controls the cooling output of the evaporator according to the state of the refrigerant in the evaporator, which can undoubtedly enable the evaporator to maintain the best heat exchange effect under various ambient temperatures.

[0021] 2) This invention adds a step of controlling the fan speed according to the condensing pressure of the refrigerator's condenser, thereby enabling the control method of this invention to respond more quickly to changes in ambient temperature, changes in the internal temperature of the refrigerator, etc. (these changes will be more sensitively reflected in the condensing pressure). Attached Figure Description

[0022] Figure 1 This is a flowchart of the control method according to a preferred embodiment of the present invention. Detailed Implementation

[0023] The principles and features of the present invention are described below with reference to the accompanying drawings. The examples given are only for explaining the present invention and are not intended to limit the scope of protection of the present invention.

[0024] In this embodiment, the refrigerator is configured as follows: it includes at least one refrigerator compartment or one freezer compartment; at least one temperature sensor located within the compartment (the compartment is a collective term for both the refrigerator and freezer compartments); at least two temperature sensors located on the evaporator; at least one ambient temperature sensor; at least one pressure sensor; at least one inverter fan; at least one compressor; and at least one condenser. The inverter fan is mounted above the evaporator and is used to release the evaporator's cooling capacity into the compartment. The compartment temperature sensor is used to obtain the current temperature of the compartment; the evaporator temperature sensor is used to obtain the current temperatures of the evaporator's inlet and outlet; the ambient temperature sensor is used to obtain the current ambient temperature; and the condenser pressure sensor is used to obtain the current condensing pressure.

[0025] Generally, the compressor starts when the refrigerator is powered on, or when the refrigerator temperature exceeds the set temperature range after the compressor has stopped running for a period of time. In this case, the refrigerator will automatically control the compressor to start running.

[0026] In this embodiment, the variable frequency fan speed is divided into 7 levels, with a speed difference of 100 rpm between different levels. During compressor operation, the temperature difference between the evaporator inlet and outlet is obtained through an evaporator temperature sensor, and the condensing pressure is obtained through a condenser pressure sensor. Based on the temperature difference between the evaporator inlet and outlet and the condensing pressure, the fan is controlled to operate at the corresponding speed. If the fan runs continuously at the same speed for a specified period of time and then the compressor stops, the variable frequency fan is controlled to operate at a lower speed.

[0027] like Figure 1 The diagram shown is a flowchart illustrating the control method for the refrigerator inverter fan in this embodiment. As can be seen from the diagram, this control method includes the following steps:

[0028] 1) The compressor starts;

[0029] 2) Determine if this is the first power-on:

[0030] If so, the fan runs at a preset speed, usually set to the maximum speed;

[0031] If not, proceed to the next step;

[0032] 3) Determine if the compressor's last running time was longer than the preset time, such as 5 minutes;

[0033] If so, the fan will run at the speed it was at during the last shutdown and proceed to the next step;

[0034] If not, the fan will run at a speed one level lower than the speed at which it last stopped, and proceed to the next step;

[0035] 4) Every time the fan runs for a preset time, such as 1 minute, collect the evaporator inlet temperature T1, evaporator outlet temperature T2, and condenser pressure P, and calculate the temperature difference between the two points ΔT = T2 - T1.

[0036] 5) Determine if △T is less than the first preset value A. If so, increase the fan speed by 1 level and return to step 4);

[0037] Determine if △T is greater than the second preset value B. If so, reduce the fan speed by 1 level and return to step 4.

[0038] Determine if P is less than the third preset value C. If so, reduce the fan speed by 1 level and return to step 4.

[0039] Determine if P is greater than the fourth preset value D. If so, increase the fan speed by one level and return to step 4.

[0040] Step 3) is used to avoid frequent short-term starts of the compressor, which helps to extend the compressor's lifespan.

[0041] In step 5), B is greater than A, and D is greater than C.

[0042] Thresholds A and B are set to control the evaporator outlet temperature, ensuring it remains consistent with the inlet temperature to maintain optimal heat exchange performance. In this embodiment, A = -1 and B = 1. A lower outlet temperature than inlet temperature indicates incomplete refrigerant evaporation, requiring enhanced heat exchange. If the evaporator outlet temperature is more than 1°C higher than the inlet temperature, some of the refrigerant inside the evaporator transforms into a superheated gaseous state. In this superheated gaseous state, the refrigerant's specific volume increases dramatically, occupying more heat exchange area and reducing heat exchange efficiency; therefore, its heat exchange capacity needs to be reduced.

[0043] When the condensing pressure P increases, the refrigerant flow rate into the evaporator increases, and the corresponding fan speed should also increase; conversely, the fan speed decreases. Setting the thresholds C and D allows for optimal matching between the fan speed and the refrigerant flow rate.

[0044] This invention regulates the fan speed by coordinating ΔT and P. Although changes in condenser pressure affect the refrigerant flow, the feedback of the evaporator inlet and outlet temperature difference ΔT has a certain lag. By combining this with the setting of the P value, a reaction can be made in advance, and then the ΔT setting can be used for control, which can make more precise control over the heat exchange of the evaporator.

[0045] When setting the third preset value C and the fourth preset value D, the ambient temperature Tam and the refrigerant type should be taken into account. Taking R600a refrigerant as an example, the recommended configuration for C and D is as follows: C = 0.1758 * (Tam + 20). 2 +0.65*(Tam+20)+207.09, D=0.1758*(Tam+24)2 +0.65*(Tam+24)+207.09.

[0046] This invention adjusts the fan speed by controlling the evaporator inlet and outlet temperatures and the condenser pressure, so that the heat exchange efficiency of the evaporator can achieve optimal matching effect under different ambient temperatures.

[0047] This invention is not limited to the specific embodiments described above. Based on the above content and in accordance with common technical knowledge and conventional methods in the field, without departing from the basic technical concept of this invention, this invention can also make other equivalent modifications, substitutions or alterations, all of which fall within the protection scope of this invention.

Claims

1. A method for controlling a refrigerator inverter fan, wherein the fan is used to promote the release of cooling capacity from the refrigerator's evaporator, characterized in that... It includes the following steps: The evaporator has an inlet temperature of T1 and an outlet temperature of T2. The fan speed is controlled based on the temperature difference between the evaporator inlet and outlet, ΔT = T2 - T1. Specifically: If ΔT is less than -1, the fan speed increases by 1 level; If ΔT is greater than 1, the fan speed is reduced by 1 level; The control method further includes controlling the fan speed according to the condensing pressure of the refrigerator's condenser.

2. The control method according to claim 1, characterized in that, Specifically, it includes: Determine whether the refrigerator compressor is being powered on for the first time: If so, control the fan to run at its maximum speed. If not, determine whether the compressor's previous running time was greater than a preset time: If so, the fan operates at the speed it was at during the last shutdown; If not, the fan will operate at a speed one level lower than the speed at which it was last stopped; Then, every preset running time, the fan collects the evaporator inlet temperature T1, evaporator outlet temperature T2, and condenser pressure P, and calculates the temperature difference between the two locations ΔT = T2 - T1: If ΔT is less than -1, the fan speed increases by 1 level; If ΔT is greater than 1, the fan speed is reduced by 1 level; If P is less than the third preset value C, the fan speed is reduced by 1 level; If P is greater than the fourth preset value D, the fan speed increases by 1 level; D is greater than C.

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