BMW air conditioning heating water valve working principle and voltage

Cooling water circulation routes: The thermostat can make the cooling water have three circulation routes: small circulation, large circulation and mixed circulation.

1. Small cycle: When the engine water temperature is lower than 76°C, the main thermostat valve is closed, the bypass valve is opened, and the cooling water channel from the cylinder head to the radiator is cut off. The cooling water flows out from the cylinder head water jacket, enters the water pump through the thermostat bypass valve and bypass pipe, and is sent to the cylinder block water jacket through the water pump. Since the cooling water does not dissipate heat through the radiator, the engine temperature can increase rapidly. This type of cycle is called a small cycle.

2. Large cycle: When the engine water temperature is higher than 86°C, the main thermostat valve opens and the bypass valve closes. All the cooling water enters the radiator through the main valve for heat dissipation, and the water temperature drops rapidly, and then is sent to the cylinder block water jacket by the water pump. This type of cycle is called a macrocycle.

3. Mixed cycle: When the water temperature is between 76 and 86°C, the main valve and the bypass valve of the thermostat are partially open. At this time, both large and small cycles exist, and only part of the cooling water is dissipated through the radiator. 2. Working principle of wax thermostat Paraffin is solid at normal temperature. When the water temperature is lower than 349K (76℃), the main valve is completely closed and the bypass valve is fully opened. The water from the cylinder head directly enters the water pump through the bypass pipe. Therefore it is called a small cycle. Since the water only flows between the water pump and the water jacket without passing through the radiator, and the flow rate is small, the cooling intensity is weak.

When the engine water temperature reaches above 349K (76°C), the paraffin gradually turns into a liquid state, and the volume increases accordingly, forcing the rubber tube to shrink, thereby pushing upward on the lower cone surface of the center rod. Since the upper end of the rod is fixed, the center rod produces a downward reverse thrust on the rubber tube and the induction body, overcoming the spring tension to gradually open the main valve and gradually reduce the opening of the bypass valve.

Reason for installing a warm water valve:

If there is no valve, no matter whether it is winter or summer, the air conditioner is on or the heater is on, as long as the engine is running, there will be coolant with a temperature of more than 90 degrees. A small water tank circulates in the compartment. It's normal in winter because we need warm air. However, in the summer, this is redundant, because things over 90 degrees are still dissipating heat in the car. It is already hot outside, and the heat is dissipated in the car, and part of the temperature dropped by the air conditioner will definitely offset the heat emitted. . After driving for a certain distance, you can stop and touch the pipe above the accelerator. Be careful not to burn your hands. Warm it up. It is just a water pipe and not a water tank. Many people can feel it. If you drive for a long time, the pipe on your right leg will The bottom of the central control panel is hot to the touch. This is because the heater water tank is dissipating heat.