What is an Electronic Expansion Valve? What is the use of an electronic expansion valve

First, the role of electronic expansion valve.

An electronic expansion valve is a device that can automatically adjust parameters such as condensation pressure, evaporation pressure, evaporation temperature and refrigerant flow in a refrigeration system. In refrigeration systems, electronic expansion valves regulate the inflow and outflow of refrigerant to enable the compressor to operate at optimal conditions, thereby improving energy efficiency, reducing energy consumption, and extending the life of the refrigeration system.

Second, the principle of electronic expansion valve.

The electronic expansion valve consists of an electromagnet, a main part, a regulating component, and a sensor. When the refrigerant in the refrigeration system passes through the electronic expansion valve, the electromagnet attracts the magnetic substance, causing the expansion valve to open; Conversely, when the electromagnet is not affected by the current, the expansion valve closes. The regulating part is responsible for adjusting the opening of the expansion valve to control the pressure and temperature of the refrigeration system.

3. The importance of electronic expansion valves.

The electronic expansion valve has a great impact on the refrigeration system, not only to control the flow of refrigerant, but also to improve the stability and accuracy of the refrigeration system. Under low load conditions, the electronic expansion valve can maintain the stability of the refrigeration effect, and at the same time, it can also improve the response speed of the refrigerant flow, making the operation of the refrigeration system more efficient.

Fourth, the selection of electronic expansion valves.

When selecting an electronic expansion valve, it should be selected based on factors such as pressure, temperature, flow and type of refrigerant of the refrigeration system. At the same time, aspects such as the accuracy, control range and durability of the electronic expansion valve should also be taken into account.

5. Maintenance of electronic expansion valves.

Electronic expansion valves require regular cleaning, calibration, and replacement of components during use to ensure proper functioning. At the same time, care should be taken to avoid damage to the electronic expansion valve caused by excessive pressure or excessive temperature, and it is best to maintain it once a year.

The electronic expansion valve is a new type of throttling control device, which uses the electrical signal generated by the adjusted parameters to control the voltage or current applied to the expansion valve, and then adjusts the opening of the expansion valve to realize the normal liquid supply to the evaporator. Figure 4-28 shows the outline drawing.

Figure 4-28 Outline diagram of an electronic expansion valve.

Electronic expansion valves can be divided into two categories: electromagnetic electronic expansion valves and electric electronic expansion valves. Among them, the electric electronic expansion valve is divided into two types: direct-acting electric electronic expansion valve and reduced-type electric electronic expansion valve.

The electronic expansion valve overcomes the shortcomings of slow signal feedback, low control accuracy and narrow adjustment range of the thermodynamic expansion valve, and provides conditions for the intelligent control of the refrigeration device.

Electronic expansion valvesThe role is as follows:

1. Throttling.

Liquid refrigerants at high temperature and pressure.

After throttling through the throttle hole of the expansion valve, it becomes a low-temperature and low-pressure mist hydraulic refrigerant, creating conditions for the evaporation of the refrigerant.

2. Control the flow of refrigerant.

Enter the vaporizer.

After passing through the evaporator, the refrigerant evaporates from the liquid state to the gaseous state, absorbing heat and reducing the temperature in the car. The expansion valve controls the flow of refrigerant to ensure that the outlet of the evaporator is completely gaseous refrigerant. If the refrigerant flow rate is too small, the evaporation will be completed in advance, resulting in insufficient refrigeration.

How the Electronic Expansion Valve Works:

The electronic expansion valve adjusts the liquid supply of the evaporator through the preset program of the internal dust beating, because it is more in line with the requirements of the integration of refrigeration motors, and the electronic expansion valve gradually replaces the thermodynamic expansion valve.

At present, there are two main types of electronic expansion valves: solenoid expansion valves and electric expansion valves, and the working principles of the two are somewhat different. The solenoid expansion valve has an electromagnetic coil inside.

The flow rate of the system is controlled by means of an electromagnetic coil as a medium. Before the solenoid coil is energized, the valve pin is open, and after the solenoid coil is energized, the opening of the valve pin is controlled by the voltage on the solenoid coil.

Thus, the voltage of the solenoid coil controls the flow of the expansion valve, and the response of the solenoid expansion valve is fast, and the refrigeration system is usually energized all the time when it is working.

The electric expansion valve is a type of stepper motor.

A device that is driven by a logical digital signal supplied to a stepper motor.

to control the movement of the thread-driven valve pin into the inlet, so as to control the flow and area of the valve.

In the automotive air conditioning system, the expansion valve is a key component, what are the classifications of the expansion valve and what is the function of the expansion valve?

At present, there are up to two types of F-type expansion valves and H-type expansion valves used in automotive air conditioners.

<> whether it is an F-type expansion valve or an H-type expansion valve, the working process is the same, the automobile air-conditioning expansion valve is generally installed at the entrance of the evaporator, which is the demarcation point between high pressure and low pressure of the automobile air-conditioning refrigeration system, after the high-temperature and high-pressure supercooled liquid from the condenser enters the expansion valve, due to the reduction of the internal section of the expansion valve, so as to achieve the effect of throttling, the refrigerant pressure decreases, and the refrigerant fluid channel suddenly becomes larger after the expansion valve, and the saturated liquid expands rapidly and becomes a low-temperature and low-pressure unsaturated liquid. That is, it becomes a refrigerant in a gas-liquid state, so that the evaporator heat works in the best state.

From the above working process, it can be concluded that the expansion valve of automobile air conditioner has three main functions. Lead wax scattered.

1. Due to the small size of the inlet of the expansion valve of the automobile air conditioner, the refrigerant pressure can be reduced, which has the effect of throttling and depressurizing.

2. The expansion valve of automobile air conditioning can automatically adjust the flow rate of refrigerant according to the size of the inlet pressure, so as to stabilize the temperature in the car and the comfort of the whole vehicle.

3. Control the flow of refrigerant to prevent liquid shock and abnormal overheating. The expansion valve uses the temperature sensing bag as the temperature sensing element to control the flow rate to ensure that the evaporator outlet has a certain amount of superheat. Prevents liquid refrigerant from liquid shock to the compressor from the local source.

The expansion valve is an important part of the cold system, which is generally installed between the reservoir and the evaporator. The expansion valve makes the liquid refrigerant at medium temperature and high pressure brighten up through its throttling into wet steam at low temperature and low pressure, and then the refrigerant absorbs heat in the evaporator to achieve the refrigeration effect, and the expansion valve controls the valve flow through the superheat change at the end of the evaporator to prevent the underutilization of the evaporator area and the phenomenon of knocking the cylinder.

The driving mode of the electronic expansion valve is that the controller calculates the parameters collected by the sensor, sends an adjustment command to the drive board, and the drive board outputs an electrical signal to the electronic expansion valve to drive the action of the electronic expansion valve. The electronic expansion valve only takes a few seconds from the fully closed to the fully open state, the reaction volt and action speed is fast, there is no static bending combustion state superheat, and the opening and closing characteristics and speed can be artificially set, especially suitable for the use of heat pump units with severe virtual motion under working conditions.

There is a hole on the side of the expansion valve of the automobile air conditioner, which can be directly adjusted by using the old beam, and the twist is smaller when it is twisted inward, and it is adjusted larger when twisted outward. The way to judge whether the expansion valve of the automobile air conditioner is large or small is to judge by observing the pressure of the air conditioner.

If the high pressure is high and the low pressure is low, the expansion valve is not normal. If the expansion valve is not normal, it will affect the refrigeration state of the air conditioner.

Turn the superheat adjustment bolt and observe the low pressure pressure: rotate the adjusting bolt of the valve in the opposite direction, the spring elasticity increases, the opening of the valve decreases, that is, the flow rate decreases. Rotate the adjusting bolt in the opposite direction, the spring elasticity weakens, and the opening of the valve increases, that is, the flow rate increases.

Generally, the bolt is rotated once, and the superheat change is about 0 degrees. The slag expansion valve is a highly sensitive component in the refrigeration system, and special care should be taken during maintenance to prevent damage.

1. Throttling and depressurizing.

The expansion valve makes the high-temperature and high-pressure liquid refrigerant from the condenser throttle and depressurize into a low-temperature and low-pressure mist refrigerant that is easy to evaporate into the evaporator, and divides the refrigerant into the high-pressure side and the low-pressure side, but the liquid state of the working fluid does not change.

2. Automatically adjust the refrigerant flow rate.

The expansion valve automatically regulates the flow into the evaporator to meet the requirements of the refrigeration cycle.

3. Control the flow of refrigerant.

Prevents liquid shock and abnormal overheating. (Liquid hammer phenomenon: The refrigerant liquid (or lubricating oil collapsing sail) is sucked into the compressor, resulting in a hydraulic shock accident of the compressor.

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Chinese name. Electric vehicle.

Foreign name. Battery Electric Vehicle is a pilot company.

Audi, BMW, Daimler, Ford, GM, Porsche, Volkswagen.

System structure. Electric drive, speed control stool rotten control, transmission device.

Impetus. On-board power supply.

Class. Battery electric vehicles (BEVs), hybrid electric vehicles (HEVs), fuel cell vehicles (FCEVs).

The main species. Types of electric vehicles: BEVs, HEVs, and FCEVs.

Electric. Electricity.

The expansion valve is an important component in the refrigeration system and is generally installed between the reservoir and the evaporator. The expansion valve makes the liquid refrigerant at medium temperature and high pressure become wet steam at low temperature and low pressure through its throttling, and then the refrigerant absorbs heat in the evaporator to achieve the refrigeration effect, and the expansion valve controls the valve flow through the superheat change at the end of the evaporator to prevent the underutilization of the evaporator area and the phenomenon of knocking the cylinder.

When the high-pressure refrigerant liquid condensed by the condenser passes through the throttle valve, the pressure drops due to obstruction, resulting in the vaporization of part of the refrigerant liquid, and at the same time absorbs the latent heat of gasification, and its own temperature is also reduced accordingly, becoming a wet steam at low temperature and low pressure, and then enters the evaporator for several days.

The thermostatic expansion valve is installed at the inlet of the evaporator, often referred to as the expansion valve, and has two main functions:

1) Throttling: The liquid refrigerant with high temperature and high pressure becomes a mist hydraulic refrigerant with low temperature and low pressure after throttling through the throttle hole of the expansion valve, creating conditions for the evaporation of the refrigerant;

2) Control the flow of refrigerant: The liquid refrigerant entering the evaporator, after passing through the evaporator, the refrigerant evaporates from the liquid state to the gaseous state, absorbs heat, and reduces the temperature in the car. The expansion valve controls the flow of refrigerant to ensure that the outlet of the evaporator is completely gaseous refrigerant. If the refrigerant flow rate is too small, the evaporation will be completed in advance, resulting in insufficient refrigeration.

It mainly plays the role of throttling and depressurizing and regulating the flow rate. At the same time, it also has the function of preventing wet compression and liquid shock, protecting the compressor and abnormal overheating.

The superheat signal can be collected through the temperature sensor and pressure sensor set at the evaporator outlet (sometimes the temperature sensor installed in the middle of the evaporator is also used to collect the evaporation temperature), and the opening of the expansion valve can be controlled by feedback adjustment.

Feedforward and feedback compound adjustment can also be used to eliminate the superheat control lag caused by the heat capacity of the evaporator tube wall and the sensor, improve the quality of system adjustment, and control the superheat within the target range in a wide evaporation temperature area.

The electronic expansion valve is mainly composed of four parts:

Rotor: Equivalent to the rotor of a synchronous motor, its connection valve stem controls the size of the valve hole opening.

Stator: a stator equivalent to a synchronous electron; It converts electrical energy into a magnetic field to drive the rotor to turn.

Valve pin (core): It is driven by a rotor, the end is tapered, and it moves up and down for flow regulation.

Valve body: generally made of brass.