Hydrogen-powered Vehicles: Electronic water pump
structure and working principle
Excessive engine temperature will reduce the lubrication ability of the engine oil, causing increased wear of the parts. When the temperature reaches a certain value, it will cause serious faults such as engine cylinder pulling or burning, and eventually cause the engine to burn out and be scrapped. The water pump is an important component of the automobile engine cooling system. Its main function is to drive the coolant circulation, absorb the engine's excess heat and transfer it to the outside air through the heat dissipation device to prevent the engine temperature from being too high.
Water pumps are divided into traditional mechanical water pumps and electronic water pumps. Traditional engines generally use mechanical water pumps, which drive the water pump bearings and impellers to rotate through pulleys. The coolant in the water pump is driven by the impeller to rotate together, and is thrown to the edge of the water pump housing under the action of centrifugal force, while generating a certain pressure, and then flows out from the outlet or water pipe. The pressure at the center of the impeller is reduced due to the coolant being thrown out. The coolant in the water tank is sucked into the impeller through the water pipe under the pressure difference between the water pump inlet and the impeller center, realizing the reciprocating circulation of the coolant.
Traditional mechanical water pumps work based on engine speed, which means that even in cold start and low-load high-speed conditions where flow demand is not high, a lot of power is still needed to drive. At this time, the cooling capacity provided is far greater than the actual demand of the engine, and a lot of power is needed to drive it, which will cause the engine's power performance and economy to decline.
The working principle of the electronic water pump is as follows: The ECU (electronic control unit) adjusts the duty cycle through PWM (pulse width modulation) according to feedback signals such as water temperature, and transmits the signal to the controller inside the electronic water pump. The controller controls the motor to rotate according to the duty cycle, thereby driving the impeller rotor to rotate, thereby realizing the circulation of coolant.
The electronic water pump consists of a pump housing, an impeller, a sealing ring, a motor housing, an electrical plug, a motor assembly, a bearing, a rotor, a controller, a controller seat, a back cover, fixing bolts, etc.
Electronic water pump structure diagram
The ECU adjusts the duty cycle through PWM according to feedback signals such as water temperature. The controller connects the wiring harness through the electrical plug, and then controls the motor to drive the impeller and rotor according to the duty cycle, thereby realizing the coolant circulation and ensuring the precise control of the coolant flow; the sealing ring ensures the sealing between the pump housing and the motor housing, the controller seat and the back cover; the pump housing, the motor housing, and the back cover seal the internal components of the electronic water pump in a dust-free environment to ensure the reliability of the electronic water pump.
2. Characteristics of electronic water pumps
1) Provide timely and appropriate cooling capacity, low energy consumption, high efficiency, and realize precise control of the coolant flow according to information such as water temperature, reduce the coolant flow distance, and reduce the water pump displacement by about 60%.
2) Reduce friction. The electronic water pump is electrically driven. Compared with the mechanical water pump, which is driven by the accessory belt, it reduces friction work. The NEDC (New European Driving Cycle, which is the European endurance test standard) cycle can reduce fuel consumption by about 2%.
3) Accelerate warm-up. For hybrid engines, due to frequent start-stop, a faster warm-up speed is required. Since the displacement of the electronic water pump can be controlled in real time, reducing the coolant flow during cold start can achieve the effect of accelerating warm-up, reducing fuel consumption and emissions.
4) Longer service life, continuous working time is more than 20,000 hours.
5) The risk of water leakage is greatly reduced. The impeller of the mechanical water pump is pressed on the water pump bearing with an interference fit, while the integrated magnetic impeller of the electronic water pump is driven by a magnetic core installed in the water pump housing, which can achieve the separation of the water cavity and the outside, remove the water seal, and reduce the risk of friction loss and water leakage.
6) Flexible control mode (PWM, bus). 7) Multiple working protections (overtemperature, overvoltage, overcurrent, etc.).
