What does a car expansion valve do, and what can it cause if it breaks?

The function of the automobile expansion valve: it is the main component of the automobile air conditioning and refrigeration system, which is installed at the inlet of the evaporator and is the dividing point between the high and low pressure of the automobile air conditioning and refrigeration system.

If it is broken, it will lead to: the low pressure is abnormal, either too low or not too high.

Functions of Automobile Expansion Valve:

The high-pressure liquid refrigerant from the liquid storage dryer is throttled and depressurized, and the liquid refrigeration dose entering the evaporator is adjusted and controlled to adapt to the change of refrigeration load, and at the same time, the liquid shock phenomenon of the compressor can be prevented, that is, the unevaporated liquid refrigerant is compressed after entering the compressor, which is easy to cause damage to the compressor valve plate and abnormal overheating of the vapor at the outlet of the evaporator.

The expansion valve is installed at the inlet of the evaporator, often called the expansion valve, and has two main functions:

1.Throttling: After the high-temperature and high-pressure liquid refrigerant is throttled 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: Once the liquid refrigerant enters the evaporator, the refrigerant is evaporated into a gaseous state, absorbing heat and reducing the temperature inside the vehicle.

The expansion valve controls the flow of refrigerant to ensure that the outlet of the evaporator is completely gaseous refrigerant, if the flow rate is too large, the outlet contains liquid refrigerant, which may enter the compressor and produce liquid shock; If the refrigerant flow rate is too small, the evaporation will be completed in advance, resulting in insufficient refrigeration.

Hello! It is to control the length of the water channel circulation of the engine cooling water (when the circulating water channel is long, the cooling fan ** reduces the temperature of the cooling water, and the circulating water channel is short to increase the engine warm-up speed), if it is broken when it is closed, it will cause the water temperature to be very high, if it is bad when it is turned on, it will cause the engine to warm up slowly, and it will also increase fuel consumption! (Warm-ups are most useful in winter).

Control the pressure ratio of the two ends of the air conditioner, if it is broken, the pressure at both ends of the high and low pressure of the air conditioner may be the same, or there is pressure at one end and there is no pressure at the other end.

The impact of a broken expansion valve in an automobile air conditioner is as follows:

The expansion valve is an important component in the refrigeration system and is generally installed between the reservoir and the evaporator. The expansion valve is composed of three parts: the valve body, the temperature sensing bag, and the balance pipe.

The expansion valve of automobile air conditioner mainly plays the role of throttling and reducing pressure 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.

In the refrigeration system, the expansion valve is one of the four major components of the refrigeration system (compressor, condenser, throttle valve, evaporator). Throttle valves can also be called expansion valves or regulating valves.

From the balance mode, the expansion valve can be divided into two types: internal balance type and external balance type. The equilibrium pressure is taken at the inlet of the evaporator for the internally balanced type, and the equilibrium pressure is taken at the outlet of the evaporator for the externally balanced type. Internally balanced expansion valves are generally used in household air conditioners.

The cooling capacity of automobile air conditioners is generally relatively large, and the pressure loss of refrigerant in the evaporator is also large, so only the external balanced type is used.

From the adjustment structure of superheat, the expansion valve is divided into internal adjustment type and external adjustment type. The internal adjustment type can only be adjusted before the installation of the air conditioning system, and its advantages are that it is small in size and compact in structure, which is suitable for batch stereotyped products. The externally adjustable type can be adjusted at any time on the air conditioning system according to the situation, which has a great deal of flexibility, but the increase in parts makes it larger in size and weight.

Hello, the performance is that the low-pressure pipe does not ice hands, the drying bottle is frosted, the condenser is frosted, the expansion valve or condenser can not hear the swishing sound, the high pressure and low pressure are abnormal (the high pressure is very high, the low pressure has no pressure or is very small, and the throttle does not respond or the reaction is not obvious), the temperature of the high-pressure pipe is abnormal, and so on are the reasons why the expansion valve is broken or cannot be opened.

The phenomenon that the expansion valve of the automobile air conditioner is broken is:

There is a fault of blockage or throttling failure, resulting in no or insufficient cooling of the air conditioning and refrigeration system. Expansion valve is a relatively common component, is widely used in refrigeration system, expansion valve can make the liquid refrigerant at medium temperature and high pressure into low temperature and low pressure wet steam through its throttling, so as to control the valve flow, often installed at the refrigerant inlet of the evaporator.

The working principle of the expansion valve is:

The expansion valve regulates the refrigerant flow according to the amount of superheat of the refrigerant at the evaporator outlet. The thermostatic expansion valve controls the flow of refrigerant into the evaporator by feeling the superheat of the gaseous refrigerant at the evaporator outlet. According to the different balance methods, thermostatic expansion valves are divided into external balance and internal balance type.

It is composed of an induction mechanism, an actuator, an adjustment mechanism and a valve body. During operation, the temperature sensing bag fixed on the outlet pipe of the evaporator senses the superheating temperature of the evaporator outlet, so that the pressure in the temperature sensing package is generated, and the space on the upper part of the diaphragm is transmitted by the capillary tube, and the diaphragm transmits the signal to the thimble (actuator) in an elastic deformation mode under the action of pressure, so as to adjust the opening of the valve and control the flow of refrigerant.

Blockages of thermostatic expansion valves in refrigeration systems are frequent, including dirty blockages and "ice blockages". The main reason for dirty plugging is the presence of impurities in the system, such as welding slag, copper code, iron filings, fibers, etc.

Hello, the air conditioner will appear not to refrigerate!

If the expansion valve is damaged, the temperature difference between the two air conditioning pipes connected to it will be very large, and the temperature difference between the two pipes is generally in a small range. You can touch it with your hands.

Brief elaboration; The expansion valve is the 'watershed' between high pressure and low pressure, generally it is blocked, connect the Gaffer meter to the low pressure and high pressure pipes respectively, start the car, turn on the air conditioner, under normal circumstances, a gas pedal, low pressure decreases, high pressure rises. If the expansion valve is blocked, when refueling, the pressure of the high pressure rises very fast, the low pressure pressure does not fall, and the air conditioner does not have a cool breeze, the high-pressure pipe does not dare to touch, the high-pressure pipe and the liquid inlet pipe of the evaporation box have a viewing window, and there will be a small number of bubbles when refueling, the bubbles are thick, the refrigerant is not enough, the air bubbles are excessive.

The role of the expansion valve.

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.

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

3. Control the flow of refrigerant.

Prevents liquid shock and abnormal overheating. (Liquid shock phenomenon: The refrigerant liquid (or lubricating oil) is sucked into the compressor, causing a liquid shock accident of the compressor.)

The function of the thermostatic expansion valve in the automotive air conditioning system: The thermostatic expansion valve is installed at the inlet of the evaporator, often called the expansion valve, and has two main functions:

1) Throttling of expansion valve: After throttling through the throttle hole of the expansion valve, the liquid refrigerant with high temperature and high pressure becomes a low-temperature and low-pressure mist hydraulic refrigerant, which creates 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.

If the flow rate is too large, the outlet contains liquid refrigerant, which may enter the compressor and produce liquid shock; If the refrigerant flow rate is too small, the evaporation will be completed in advance, resulting in insufficient refrigeration.

Expansion valves are an important component in refrigeration systems and are generally installed between the reservoir and the evaporator. The phenomenon of the bad expansion valve of the automobile is that the low-pressure pipe does not freeze, the drying bottle is frosted, the condenser is frosted, the expansion valve or condenser cannot hear the whooshing sound, the high pressure and low pressure are abnormal, and the temperature of the high-pressure pipe is abnormal.

The function of the thermal expansion valve: The thermal expansion valve is installed at the inlet of the evaporator, commonly known as the expansion valve, and has two main functions:

1.Throttling: After the high-temperature and high-pressure liquid refrigerant is throttled 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: The liquid refrigerant entering the evaporator evaporates from the liquid state to the gaseous state after passing through the evaporator, absorbing heat and reducing the temperature in the vehicle.

Controls the flow of refrigerant in the expansion valve to ensure that the outlet of the evaporator is entirely gaseous refrigerant. If the flow rate is too high, the outlet contains liquid refrigerant, which may enter the compressor and generate liquid hammer; If the refrigerant flow is too low, it will evaporate prematurely, resulting in insufficient refrigeration.

Judging method:1At a temperature of 30 degrees Celsius, within 10 minutes after starting the air adjustment, the pressure on the low-pressure side is about 40ps, and the pressure on the high-pressure side is normal.

2.When the temperature is 30 degrees, after 10 minutes of starting, the pressure on the low-pressure side is 40ps, and the pressure on the high-pressure side is above, which is a problem of bad heat dissipation.

3.At a temperature of 30 degrees Celsius, the pressure on the low pressure side of the accelerator can be reduced to 22 ps after 10 minutes of starting the air conditioning system, and the pressure on the high side can be reduced to 22 ps.

4.At a temperature of 30 degrees, the air conditioning has been started for a long time, and the pressure on the high side has not yet been reached, while the pressure on the low side is around 40ps. The air conditioning system has added a calibration refrigerant, but the liquid window is still bubbling.

At the same time, there is water on the compressor casing on the low-pressure side of the compressor. Expansion valve body failure.