Linear cooling control method of environmental test box and environmental test box

Abstract

The invention discloses a linear cooling control method of an environmental test box and the environmental test box. The method comprises the following steps: determining a linear cooling rate of a to-be-controlled environmental test box; determining a linear target temperature at any moment based on the linear cooling rate; acquiring a current temperature parameter of the to-be-controlled environment test box; based on the linear target temperature and the current temperature parameter, the opening degree of a main path electronic expansion valve, the opening degree of a liquid bypass electronic expansion valve and the rotating speed of an evaporator fan of the environment test box to be controlled are calculated; based on the calculated opening degree of the main electronic expansion valve, the calculated opening degree of the liquid bypass electronic expansion valve and the calculated rotating speed of the evaporator fan, the main electronic expansion valve, the liquid bypass electronic expansion valve and the evaporator fan of the to-be-controlled environment test box are controlled to act, and linear cooling control over the to-be-controlled environment test box is achieved. The technical problem that in the linear cooling process of an existing environmental test box, the stability of a linear cooling temperature curve and the reliability of system operation are poor is solved.

Description

[0001] This application is a divisional application of the patent application filed on May 24, 2024, application number 2024106563969, entitled "A linear cooling control method for an environmental test chamber and an environmental test chamber". Technical Field

[0002] This invention relates to the field of temperature control technology, and in particular to a linear cooling control method for an environmental test chamber and an environmental test chamber. Background Technology

[0003] Currently, most linear cooling systems use fixed-frequency compressors. In the early and middle stages of cooling, the cooling capacity demand is significantly less than the compressor's capacity. Therefore, the expansion valve employs a multi-branch combination, with on / off control for different temperature ranges. When the expansion valves in different branches open, the system's cooling capacity suddenly increases, causing significant fluctuations in the linear cooling temperature curve. At this point, the system uses heating to counteract the fluctuations and achieve curve stabilization again. If the expansion valve is not properly selected or adjusted when open, it may cause liquid to be drawn into the compressor's suction, affecting system reliability. Simultaneously, fan control is also crucial. If the fan airflow is too low, the refrigerant in the evaporator cannot evaporate completely; if the fan airflow is too high, energy efficiency is poor.

[0004] Furthermore, in the initial cooling phase, the high starting temperature leads to a high compressor suction temperature. To prevent the compressor motor from overheating, liquid needs to be sprayed into the compressor suction pipe to lower the suction temperature. However, if the liquid spraying volume is not accurately controlled, liquid may be carried into the compressor suction, affecting the system's operational reliability.

[0005] Therefore, optimizing the system control and operation during the linear cooling process is crucial for the stability of the linear cooling temperature curve, system simplification, system energy saving, and system operational reliability. Summary of the Invention

[0006] This invention provides a linear cooling control method and an environmental test chamber for an environmental test chamber, which solves the technical problems of poor stability of the linear cooling temperature curve and poor system reliability in the linear cooling process of existing environmental test chambers.

[0007] In a first aspect, embodiments of the present invention provide a linear cooling control method for an environmental test chamber, the control method comprising: Determine the linear cooling rate of the controlled environment test chamber; The linear target temperature at any given time is determined based on the linear cooling rate. Obtain the current temperature parameters of the controlled environment test chamber, wherein the current temperature parameters include the internal temperature of the controlled environment test chamber, the evaporator inlet temperature, the evaporator outlet temperature, the evaporator inlet air temperature, and the compressor suction temperature; Based on the linear target temperature and the current temperature parameters, calculate the opening degree of the main circuit electronic expansion valve, the opening degree of the liquid bypass electronic expansion valve, and the evaporator fan speed of the controlled environment test chamber, respectively. Based on the calculated opening degree of the main circuit electronic expansion valve, the opening degree of the liquid bypass electronic expansion valve, and the speed of the evaporator fan, the main circuit electronic expansion valve, the liquid bypass electronic expansion valve, and the evaporator fan of the test chamber under control are respectively controlled to achieve linear cooling control of the test chamber under control. The calculation of the evaporator fan speed of the controlled environment test chamber based on the linear target temperature and the current temperature parameters includes: Based on the linear target temperature and the current temperature parameters, the evaporator fan speed formula is used. Calculate the evaporator fan speed, where, H The evaporator fan speed is [missing information]. K 3. I 3. D 3 represents the proportional coefficient, integral coefficient, and derivative coefficient of the proportional-integral-derivative control of the evaporator fan speed, respectively. h ( t This refers to the deviation in the evaporator fan speed control. t Total cooling time t At any time within, , T ai The evaporator inlet air temperature, T The temperature inside the chamber, B s The second target value in the second database. s This is the number for the linear target temperature.

[0008] Optionally, determining the linear cooling rate of the controlled environment test chamber includes: Obtain the preset temperature parameters of the controlled environment test chamber; wherein, the preset temperature parameters include at least one of the following: starting temperature, ending temperature, and total cooling time; The linear cooling rate of the controlled environment test chamber is determined using the preset temperature parameters.

[0009] Optionally, the initial temperature T0 and the final temperature T of the controlled environment test chamber can be obtained. SV And the total cooling time t, then using the formula Determine the linear cooling rate of the controlled environment test chamber, where V is the linear cooling rate.

[0010] Optionally, determining the linear target temperature at any given time based on the linear cooling rate includes: Based on the linear cooling rate, utilizingT n = T 0- Vt n Determine the linear target temperature at any given time, where, T n The linear target temperature, n The linear target temperature and any time t The corresponding number, V The linear cooling rate is... T 0 represents the starting temperature.

[0011] Optionally, calculating the opening degree of the liquid bypass electronic expansion valve of the controlled environment test chamber based on the current temperature parameter includes: Based on the linear target temperature and the current temperature parameters, the main circuit electronic expansion valve opening formula is used. Calculate the opening degree of the main circuit electronic expansion valve, where, Z The opening degree of the main circuit electronic expansion valve. K 1. I 1. D 1 represents the proportional coefficient, integral coefficient, and derivative coefficient of the proportional-integral-derivative control of the main circuit electronic expansion valve, respectively, and e(τ) is the main circuit control deviation. t Total cooling time t At any time within, , T The temperature inside the chamber, T 0 is the starting temperature. T SV The final temperature, p Main path gain coefficient, , V The linear cooling rate is... V C The rate constant is T C It is a temperature constant. T n Let n be the linear target temperature, and n be the number corresponding to the linear target temperature and the corresponding time.

[0012] Optionally, before calculating the opening degree of the liquid bypass electronic expansion valve of the controlled environment test chamber based on the current temperature parameter, the control method further includes: A first database is established to compare the evaporation temperature of the controlled environment test chamber, the temperature inside the chamber, and a first target value, wherein the first target value is a target value that is the difference between the compressor suction temperature and the evaporator outlet temperature.

[0013] Optionally, calculating the opening degree of the liquid bypass electronic expansion valve of the controlled environment test chamber based on the current temperature parameter includes: Based on the current temperature parameters, the opening formula of the liquid bypass electronic expansion valve is used. Calculate the opening degree of the liquid bypass electronic expansion valve, where, Q The opening degree of the liquid bypass electronic expansion valve. K 2. I 2. D 2 represents the proportional coefficient, integral coefficient, and derivative coefficient of the proportional-integral-derivative control of the liquid bypass electronic expansion valve, respectively, and q(τ) represents the liquid bypass control deviation. t Total cooling time t At any time within, , T a The compressor suction temperature is... T eo The outlet temperature of the evaporator. A ij The first target value in the first database. i This is the number for the evaporation temperature. j The temperature inside the chamber is designated as a number. m This is the liquid bypass gain coefficient. , T The temperature inside the chamber, T Q This is the temperature constant of the electronic expansion valve.

[0014] Optionally, after determining the linear target temperature at any given time based on the linear cooling rate, the control method further includes: A second database is established between the linear target temperature, the linear cooling rate, and the second target value, wherein the second target value is a target value representing the difference between the evaporator inlet air temperature and the chamber temperature.

[0015] In a second aspect, embodiments of the present invention provide an environmental test chamber, the environmental test chamber including a chamber body, a control system and a refrigeration system, wherein the control system executes the linear cooling control method for the environmental test chamber described in the first aspect above; The control system includes a display unit, a sensor unit, and a control unit. The sensor unit is disposed inside the housing, the display unit is disposed on the surface of the housing, and the control unit is disposed inside or outside the housing. The display unit and the sensor unit are electrically connected to the control unit. The refrigeration system is installed inside the housing and includes a compressor, a condenser, an evaporator, an evaporator fan, a main electronic expansion valve, and a liquid bypass electronic expansion valve. The main circuit electronic expansion valve, the evaporator, the compressor, and the condenser are connected in series to form a circuit. The liquid bypass electronic expansion valve is connected in parallel at both ends of the evaporator and the main circuit electronic expansion valve. The evaporator fan is located at the evaporator.

[0016] Optionally, the sensor unit includes an internal temperature sensor, an evaporator inlet temperature sensor, an evaporator inlet air temperature sensor, an evaporator outlet temperature sensor, and a compressor suction air temperature sensor. The evaporator inlet temperature sensor is located at the inlet of the evaporator; the evaporator air inlet temperature sensor is located at the air inlet of the evaporator; the evaporator outlet temperature sensor is located at the outlet of the evaporator; and the compressor suction temperature sensor is located at the compressor suction port. The control unit includes a liquid bypass electronic expansion valve control module, a main circuit electronic expansion valve control module, and a data acquisition and calculation control module. The data acquisition, calculation, and control module is electrically connected to the sensors in the sensor unit, the liquid bypass electronic expansion valve control module, and the main electronic expansion valve, respectively. The liquid bypass electronic expansion valve control module is electrically connected to the liquid bypass electronic expansion valve. The main circuit electronic expansion valve control module is electrically connected to the main circuit electronic expansion valve and the evaporator fan, respectively.

[0017] This invention discloses a linear cooling control method for an environmental test chamber and an environmental test chamber. The control method includes determining the linear cooling rate of the environmental test chamber to be controlled; determining the linear target temperature at any time based on the linear cooling rate; obtaining the current temperature parameters of the environmental test chamber to be controlled; calculating the opening degree of the main circuit electronic expansion valve, the opening degree of the liquid bypass electronic expansion valve, and the evaporator fan speed of the environmental test chamber to be controlled based on the linear target temperature and the current temperature parameters; and controlling the operation of the main circuit electronic expansion valve, the liquid bypass electronic expansion valve, and the evaporator fan of the environmental test chamber to be controlled based on the calculated opening degree of the main circuit electronic expansion valve, the opening degree of the liquid bypass electronic expansion valve, and the evaporator fan speed, thereby realizing the linear cooling control of the environmental test chamber to be controlled. This application solves the technical problems of poor stability of the linear cooling temperature curve and poor system reliability in the linear cooling process of existing environmental test chambers by accurately calculating the opening degree of the main circuit electronic expansion valve, the opening degree of the liquid bypass electronic expansion valve, and the speed of the evaporator fan, and using the calculation results to control the corresponding mechanisms. It achieves the technical effects of improving the stability of the linear cooling control of the environmental test chamber, improving the reliability of system operation, reducing system energy consumption, and simplifying the system control structure. Attached Figure Description

[0018] Figure 1This is a flowchart of a linear cooling control method for an environmental test chamber provided in an embodiment of the present invention; Figure 2 This is a structural diagram of an environmental test chamber provided in an embodiment of the present invention. Detailed Implementation

[0019] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, and not all of the structures.

[0020] It should be noted that the terms "first," "second," etc., in the specification, claims, and drawings of this invention are used to distinguish different objects, not to limit a specific order. The various embodiments of this invention described below can be performed individually or in combination with each other; the embodiments of this invention do not impose specific limitations in this regard.

[0021] Figure 1 This is a flowchart of a linear cooling control method for an environmental test chamber provided in an embodiment of the present invention, as shown below. Figure 1 As shown, the linear cooling control method of this environmental test chamber specifically includes the following steps: S101, determine the linear cooling rate of the controlled environment test chamber.

[0022] Optionally, S101 specifically includes: acquiring preset temperature parameters of the controlled environment test chamber; wherein the preset temperature parameters include at least one of the following: initial temperature, final temperature, and total cooling time; and determining the linear cooling rate of the controlled environment test chamber using the preset temperature parameters.

[0023] Specifically, the environmental test chamber is equipped with a control system, which includes a display unit, a sensor unit, and a control unit. The control unit includes a liquid bypass electronic expansion valve control module, a main circuit electronic expansion valve control module, and a data acquisition and calculation control module. The initial temperature of the environmental test chamber can be obtained through the data acquisition and calculation control module within the test chamber. T 0. Final temperature T SV And the total cooling time t, then using the formula Determine the linear cooling rate of the controlled environment test chamber, where, V The cooling rate is linear.

[0024] S102 determines the linear target temperature at any given time based on the linear cooling rate.

[0025] Optionally, S102 specifically includes: Based on linear cooling rate utilizationT n = T 0- Vt n Determine the linear target temperature at any given time, where, T n For linear target temperature, n For linear target temperature and arbitrary time t The corresponding number, V For linear cooling rate, T 0 represents the starting temperature.

[0026] S103, obtain the current temperature parameters of the controlled environment test chamber, including the internal temperature of the controlled environment test chamber, the evaporator inlet temperature, the evaporator outlet temperature, the evaporator inlet air temperature, and the compressor suction temperature.

[0027] Specifically, the control system of the environmental test chamber includes a sensor unit, which includes an internal temperature sensor, an evaporator inlet temperature sensor, an evaporator inlet air temperature sensor, an evaporator outlet temperature sensor, and a compressor suction temperature sensor, respectively used to acquire the internal temperature, evaporator inlet temperature, evaporator inlet air temperature, evaporator outlet temperature, and compressor suction temperature of the environmental test chamber under control.

[0028] S104, based on the linear target temperature and the current temperature parameters, calculate the opening degree of the main circuit electronic expansion valve, the opening degree of the liquid bypass electronic expansion valve, and the evaporator fan speed of the test chamber under control.

[0029] Specifically, after obtaining the linear target temperature and the current temperature parameters, the opening degree or speed of the main circuit electronic expansion valve, the liquid bypass electronic expansion valve, and the evaporator fan are calculated using the linear target temperature, the current temperature parameters, the main circuit electronic expansion valve opening degree formula, the liquid bypass electronic expansion valve opening degree formula, and the evaporator fan speed formula.

[0030] S105 controls the operation of the main circuit electronic expansion valve, the liquid bypass electronic expansion valve, and the evaporator fan based on the calculated opening degree of the main circuit electronic expansion valve, the liquid bypass electronic expansion valve, and the evaporator fan speed, thereby achieving linear cooling control of the test chamber.

[0031] Specifically, by using the calculated opening degree of the main circuit electronic expansion valve, the opening degree of the liquid bypass electronic expansion valve, and the evaporator fan speed to control the main circuit electronic expansion valve, liquid bypass electronic expansion valve, and evaporator fan of the environmental test chamber under test, stable linear cooling control of the environmental test chamber under test can be achieved, and the risk of liquid carryover during compressor suction can be avoided.

[0032] This application solves the technical problems of poor stability of the linear cooling temperature curve and poor system reliability in the linear cooling process of existing environmental test chambers by accurately calculating the opening degree of the main circuit electronic expansion valve, the opening degree of the liquid bypass electronic expansion valve, and the speed of the evaporator fan, and using the calculation results to control the corresponding mechanisms. It achieves the technical effects of improving the stability of the linear cooling control of the environmental test chamber, improving the reliability of system operation, reducing system energy consumption, and simplifying the system control structure.

[0033] Based on the above technical solutions, S104, the calculation of the main electronic expansion valve opening of the controlled environment test chamber based on the linear target temperature and the current temperature parameters includes: Based on the linear target temperature and current temperature parameters, the main circuit electronic expansion valve opening formula is used. Calculate the opening degree of the main circuit electronic expansion valve, where, Z The opening degree of the main circuit electronic expansion valve K 1. I 1. D 1 represents the proportional coefficient, integral coefficient, and derivative coefficient of the proportional-integral-derivative control of the main circuit electronic expansion valve, respectively; e(τ) is the main circuit control deviation. t Total cooling time t At any time within, , T The temperature inside the chamber. T 0 is the starting temperature. T SV The final temperature, p Main path gain coefficient, , V For linear cooling rate, V C The rate constant is T C It is a temperature constant. T n Let n be the linear target temperature, and n be the number corresponding to the linear target temperature and the corresponding time.

[0034] Based on the above technical solutions, before S104 calculates the opening degree of the liquid bypass electronic expansion valve of the test chamber under control based on the current temperature parameters, the control method also includes: A first database is established to compare the evaporation temperature, the internal temperature of the test chamber, and the first target value of the controlled environment test chamber. The first target value is the target value of the difference between the compressor suction temperature and the evaporator outlet temperature.

[0035] Specifically, the first target value can be an empirically based calibration value, a theoretically analyzed value, or a value obtained from experimental measurements; no specific limitations are made here. Table 1 is a record table of the first database.

[0036] Table 1. Records of the First Database Based on the above technical solutions, S104, the calculation of the liquid bypass electronic expansion valve opening of the controlled environment test chamber based on the current temperature parameters includes: Based on the current temperature parameters, the opening formula of the liquid bypass electronic expansion valve is used. Calculate the opening degree of the liquid bypass electronic expansion valve, where, Q For the opening degree of the liquid bypass electronic expansion valve, K 2. I 2. D 2 represents the proportional coefficient, integral coefficient, and derivative coefficient of the proportional-integral-derivative control of the liquid bypass electronic expansion valve, respectively, and q(τ) represents the liquid bypass control deviation. t Total cooling time t At any time within, , T a This refers to the compressor suction temperature. T eo This refers to the evaporator outlet temperature. A ij The first target value in the first database. i This is the number for the evaporation temperature. j This is a number indicating the temperature inside the chamber. m This is the liquid bypass gain coefficient. , T The temperature inside the chamber. T Q This is the temperature constant of the electronic expansion valve.

[0037] Based on the above technical solutions, in S102, after determining the linear target temperature at any time based on the linear cooling rate, the control method further includes: A second database is established to connect linear target temperature, linear cooling rate, and second target value, where the second target value is the target value of the difference between the evaporator inlet air temperature and the box temperature.

[0038] Specifically, the second target value can be an empirically based calibration value, a theoretically analyzed value, or a value obtained from experimental measurements; no specific limitations are made here. Table 2 is a record table of the second database.

[0039] Table 2. Records of the Second Database Based on the above technical solutions, S104, the calculation of the evaporator fan speed of the controlled environment test chamber based on the linear target temperature and the current temperature parameters includes: Based on the linear target temperature and the current temperature parameters, the evaporator fan speed formula is used. Calculate the evaporator fan speed, where, H This refers to the evaporator fan speed. K 3. I 3. D 3 represents the proportional coefficient, integral coefficient, and derivative coefficient of the proportional-integral-derivative control for the evaporator fan speed. h ( t This refers to the deviation in the evaporator fan speed control. t Total cooling time t At any time within, , T ai This refers to the evaporator inlet air temperature. T The temperature inside the chamber. B s The second target value in the second database. s This is the number for the linear target temperature.

[0040] Figure 2 This is a structural diagram of an environmental test chamber provided in an embodiment of the present invention.

[0041] The environmental test chamber includes a chamber body, a control system, and a refrigeration system. The control system executes the linear cooling control method of the environmental test chamber in any of the above embodiments.

[0042] The control system includes a display unit, a sensor unit, and a control unit. The sensor unit is located inside the enclosure, the display unit is located on the surface of the enclosure, and the control unit is located inside or outside the enclosure. The display unit and the sensor unit are electrically connected to the control unit. The refrigeration system is located inside the cabinet and includes a compressor 1, a condenser 2, an evaporator 3, an evaporator fan 4, a main electronic expansion valve 5, and a liquid bypass electronic expansion valve 6. like Figure 2 As shown, the main circuit electronic expansion valve 5, evaporator 3, compressor 1 and condenser 2 are connected in series to form a circuit. The liquid bypass electronic expansion valve 6 is connected in parallel at both ends of the evaporator 3 and the main circuit electronic expansion valve 5. The evaporator fan 4 is located at the evaporator.

[0043] Optionally, the sensor unit includes an internal temperature sensor 7, an evaporator inlet temperature sensor 8, an evaporator inlet air temperature sensor 9, an evaporator outlet temperature sensor 10, and a compressor suction temperature sensor 11; the evaporator inlet temperature sensor 8 is located at the inlet of the evaporator 3; the evaporator inlet air temperature sensor 9 is located at the air inlet of the evaporator 3; the evaporator outlet temperature sensor 10 is located at the outlet of the evaporator 3; and the compressor suction temperature sensor 11 is located at the suction port of the compressor 1.

[0044] The control unit includes a liquid bypass electronic expansion valve control module 12, a main circuit electronic expansion valve control module 13, and a data acquisition and calculation control module 14. The data acquisition and calculation control module 14 is electrically connected to the sensor in the sensor unit, the liquid bypass electronic expansion valve control module 12, and the main circuit electronic expansion valve control module 13, respectively. The liquid bypass electronic expansion valve control module 12 is electrically connected to the liquid bypass electronic expansion valve 6. The main circuit electronic expansion valve control module 13 is electrically connected to the main circuit electronic expansion valve 5 and the evaporator fan 4, respectively.

[0045] Specifically, the data acquisition and calculation control module 14 is used to determine the linear cooling rate of the environmental test chamber; determine the linear target temperature at any time based on the linear cooling rate; acquire the current temperature parameters of the environmental test chamber through various sensors; calculate the opening degree of the main circuit electronic expansion valve, the opening degree of the liquid bypass electronic expansion valve, and the speed of the evaporator fan based on the linear target temperature and the current temperature parameters, and then generate corresponding control commands based on the calculated opening degree of the main circuit electronic expansion valve, the opening degree of the liquid bypass electronic expansion valve, and the speed of the evaporator fan, and transmit the corresponding control commands to the liquid bypass electronic expansion valve control module 12 and the main circuit electronic expansion valve control module 13, so that the liquid bypass electronic expansion valve control module 12 and the main circuit electronic expansion valve control module 13 control the main circuit electronic expansion valve 5, the liquid bypass electronic expansion valve 6, and the evaporator fan 4 of the environmental test chamber to perform corresponding actions, thereby realizing the linear cooling control of the environmental test chamber.

[0046] The environmental test chamber provided in this embodiment of the invention uses the linear cooling control method of the environmental test chamber in the above embodiment. Therefore, the environmental test chamber provided in this embodiment of the invention also has the beneficial effects described in the above embodiment, which will not be repeated here.

[0047] In the description of the embodiments of the present invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the present invention based on the specific circumstances.

[0048] Finally, it should be noted that the above are merely preferred embodiments of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and various obvious changes, readjustments, and substitutions can be made without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments, and may include many other equivalent embodiments without departing from the concept of the present invention, the scope of which is determined by the scope of the appended claims.

Claims

1. A linear cooling control method for an environmental test chamber, characterized in that, The control method includes: Determine the linear cooling rate of the controlled environment test chamber; The linear target temperature at any given time is determined based on the linear cooling rate. Obtain the current temperature parameters of the controlled environment test chamber, wherein the current temperature parameters include the internal temperature of the controlled environment test chamber, the evaporator inlet temperature, the evaporator outlet temperature, the evaporator inlet air temperature, and the compressor suction temperature; Based on the linear target temperature and the current temperature parameters, calculate the opening degree of the main circuit electronic expansion valve, the opening degree of the liquid bypass electronic expansion valve, and the evaporator fan speed of the controlled environment test chamber, respectively. Based on the calculated opening degree of the main circuit electronic expansion valve, the opening degree of the liquid bypass electronic expansion valve, and the speed of the evaporator fan, the main circuit electronic expansion valve, the liquid bypass electronic expansion valve, and the evaporator fan of the test chamber under control are respectively controlled to achieve linear cooling control of the test chamber under control. The calculation of the evaporator fan speed of the controlled environment test chamber based on the linear target temperature and the current temperature parameters includes: Based on the linear target temperature and the current temperature parameters, the evaporator fan speed formula is used. Calculate the evaporator fan speed, where, H The evaporator fan speed is [missing information]. K 3. I 3. D 3 represents the proportional coefficient, integral coefficient, and derivative coefficient of the proportional-integral-derivative control of the evaporator fan speed, respectively. h ( τ This refers to the deviation in the evaporator fan speed control. τ Total cooling time t At any time within, , T ai The evaporator inlet air temperature, T The temperature inside the chamber, B s The second target value in the second database. s This is the number for the linear target temperature.

2. The linear cooling control method for the environmental test chamber according to claim 1, characterized in that, Determining the linear cooling rate of the controlled environment test chamber includes: Obtain the preset temperature parameters of the controlled environment test chamber; wherein, the preset temperature parameters include at least one of the following: starting temperature, ending temperature, and total cooling time; The linear cooling rate of the controlled environment test chamber is determined using the preset temperature parameters.

3. The linear cooling control method for the environmental test chamber according to claim 2, characterized in that, Obtain the initial temperature T0 and the final temperature T of the controlled environment test chamber. SV And the total cooling time t, then using the formula Determine the linear cooling rate of the controlled environment test chamber, where V is the linear cooling rate.

4. The linear cooling control method for the environmental test chamber according to claim 1, characterized in that, Determining the linear target temperature at any given time based on the linear cooling rate includes: Based on the linear cooling rate, utilizing T n = T 0- Vτ n Determine the linear target temperature at any given time, where, T n The linear target temperature, n The linear target temperature and any time τ The corresponding number, V The linear cooling rate is... T 0 represents the starting temperature.

5. The linear cooling control method for the environmental test chamber according to claim 4, characterized in that, The calculation of the liquid bypass electronic expansion valve opening of the controlled environment test chamber based on the current temperature parameters includes: Based on the linear target temperature and the current temperature parameters, the main circuit electronic expansion valve opening formula is used. Calculate the opening degree of the main circuit electronic expansion valve, where, Z The opening degree of the main circuit electronic expansion valve. K 1. I 1. D 1 represents the proportional coefficient, integral coefficient, and derivative coefficient of the proportional-integral-derivative control of the main circuit electronic expansion valve, respectively, and e(τ) is the main circuit control deviation. τ Total cooling time t At any time within, , T The temperature inside the chamber, T 0 is the starting temperature. T SV The final temperature, p Main path gain coefficient, , V The linear cooling rate is... V C The rate constant is T C It is a temperature constant. T n Let n be the linear target temperature, and n be the number corresponding to the linear target temperature and the corresponding time.

6. The linear cooling control method for the environmental test chamber according to claim 1, characterized in that, Before calculating the opening degree of the liquid bypass electronic expansion valve of the controlled environment test chamber based on the current temperature parameter, the control method further includes: A first database is established to compare the evaporation temperature of the controlled environment test chamber, the temperature inside the chamber, and a first target value, wherein the first target value is a target value that is the difference between the compressor suction temperature and the evaporator outlet temperature.

7. The linear cooling control method for the environmental test chamber according to claim 6, characterized in that, The calculation of the liquid bypass electronic expansion valve opening of the controlled environment test chamber based on the current temperature parameters includes: Based on the current temperature parameters, the opening formula of the liquid bypass electronic expansion valve is used. Calculate the opening degree of the liquid bypass electronic expansion valve, where, Q The opening degree of the liquid bypass electronic expansion valve. K 2. I 2. D 2 represents the proportional coefficient, integral coefficient, and derivative coefficient of the proportional-integral-derivative control of the liquid bypass electronic expansion valve, respectively, and q(τ) represents the liquid bypass control deviation. τ Total cooling time t At any time within, , T a The compressor suction temperature is... T eo The outlet temperature of the evaporator. A ij The first target value in the first database. i This is the number for the evaporation temperature. j The temperature inside the chamber is designated as a number. m This is the liquid bypass gain coefficient. , T The temperature inside the chamber, T Q This is the temperature constant of the electronic expansion valve.

8. The linear cooling control method for the environmental test chamber according to claim 1, characterized in that, After determining the linear target temperature at any given time based on the linear cooling rate, the control method further includes: A second database is established between the linear target temperature, the linear cooling rate, and the second target value, wherein the second target value is a target value representing the difference between the evaporator inlet air temperature and the chamber temperature.

9. An environmental test chamber, characterized in that, The environmental test chamber includes a chamber body, a control system, and a refrigeration system. The control system executes the linear cooling control method for the environmental test chamber according to any one of claims 1-8. The control system includes a display unit, a sensor unit, and a control unit. The sensor unit is disposed inside the housing, the display unit is disposed on the surface of the housing, and the control unit is disposed inside or outside the housing. The display unit and the sensor unit are electrically connected to the control unit. The refrigeration system is installed inside the housing and includes a compressor, a condenser, an evaporator, an evaporator fan, a main electronic expansion valve, and a liquid bypass electronic expansion valve. The main circuit electronic expansion valve, the evaporator, the compressor, and the condenser are connected in series to form a circuit. The liquid bypass electronic expansion valve is connected in parallel at both ends of the evaporator and the main circuit electronic expansion valve. The evaporator fan is located at the evaporator.

10. The environmental test chamber according to claim 9, characterized in that, The sensor unit includes an internal temperature sensor, an evaporator inlet temperature sensor, an evaporator inlet air temperature sensor, an evaporator outlet temperature sensor, and a compressor suction air temperature sensor. The evaporator inlet temperature sensor is located at the inlet of the evaporator; the evaporator air inlet temperature sensor is located at the air inlet of the evaporator; the evaporator outlet temperature sensor is located at the outlet of the evaporator; and the compressor suction temperature sensor is located at the compressor suction port. The control unit includes a liquid bypass electronic expansion valve control module, a main circuit electronic expansion valve control module, and a data acquisition and calculation control module. The data acquisition, calculation, and control module is electrically connected to the sensors in the sensor unit, the liquid bypass electronic expansion valve control module, and the main electronic expansion valve, respectively. The liquid bypass electronic expansion valve control module is electrically connected to the liquid bypass electronic expansion valve. The main circuit electronic expansion valve control module is electrically connected to the main circuit electronic expansion valve and the evaporator fan, respectively.

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