Car engine pump (with photos)
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September 27 06:00:56, 2024
Pump is an important part of the engine cooling system, its role is to pump coolant, the coolant flow in the engine cooling water quickly to take away the engine heat generated by the work to maintain the normal operating temperature of the engine. Pumps have a large pump capacity, such as a V8 engine pump, which pumps at about 750 L / h of idle speed. Pump classification Figure 1 Mechanical Pump According to the different driving methods, pumps are generally divided into mechanical pump (Figure 1) and electric pump (Figure 2). At present, most engines use mechanical water pumps, and electric water pumps have been used on some newly developed and technologically advanced engines such as the BMW 6 Series (E63). Figure 2 electric pump and installation location (1) mechanical pump mechanical pump driven by the engine crankshaft through the transmission tape, and its speed is proportional to the engine speed. Mechanical pumps have advantages and disadvantages of working methods. When the engine working under high-speed and high-load conditions, the engine generates more heat and the high speed of the pump increases the circulating flow of the coolant so as to improve the cooling capacity of the engine. When the engine is working at low speed and heavy load When, for example, pulling other vehicles or air conditioning, low engine speed at this time the pump speed is also low, thus reducing the cooling capacity of the engine. (2) electric pump Electric pump by the engine control unit through the current control, it is not affected by the engine speed at that time, according to the actual cooling needs of the engine to work flexibly. As the electric pump consumes very little engine power, the fuel consumption of the engine can be reduced with the electric pump. The following is the most common mechanical pump, for example, explain the car pump related knowledge. Structure of the pump The water pump used in automobile engine is a centrifugal pump, which consists of shell, impeller, bearing, pump shaft, water seal and drive pulley. (1) Housing The pump housing is made of cast iron or cast aluminum. Cast iron shell wall thickness and quality, with the lighter weight requirements of the engine, only some large commercial vehicles are still using cast iron shell pump. Many cast iron housings also feature partial waterways and thermostat mounting chambers, which adds further weight to the housing. Most car pumps use cast aluminum housing, and the size of the shell is getting smaller and smaller, many of the shell no longer has the function of waterways. (2) Impeller The pump impeller is made of metal, such as cast iron, or engineering plastic. The impeller adopts a semi-circular arc, double circular arc or multi-circular arc blades that bend backward. The blades are in the same direction as the water flow, and pump water efficiency is high. Made of cast iron pump impeller quality, but higher mechanical strength, is now more used in large commercial vehicles on the engine. Plastic impeller easy to miniaturization and lightweight, and good corrosion resistance, easy to control the shape processing, so more and more car engine pumps use plastic impeller. Figure 3 shaft bearing (3) bearing water pump bearing is an important part of the pump, a considerable part of the pump failure is caused by the pump bearing damage. As the engine gradually to the direction of high-power, water pump bearings need to have higher thermal stability, greater load carrying capacity and better sealing, so some automotive pumps use shaft bearings (Figure 3). Shaft bearing is actually a simplified structure of the double bearing, the two bearing no inner ring, rolling the raceway directly on the pump shaft, the two bearing outer ring made of a whole, both ends with The seal is sealed to form a shaft bearing. Under the same carrying capacity, the size of the shaft bearing is smaller than the bearing of the general type. Under the same size, the bearing capacity of the shaft bearing is larger than the bearing of the general type. (4) pump shaft pump shaft is generally made of forged steel. The pump impeller is mounted on one end of the pump shaft and the pump shaft is supported on the pump housing by the bearing. The other end of the pump shaft mounted drive pulley, the crankshaft by the toothed belt or V-shaped tape drive. (5) The role of water seal is to seal the coolant to avoid leakage, while the coolant and pump bearings isolated to protect the bearings. At present the pump has been widely used double-layer ceramic water seal, two coaxial ceramic water seal installed by the coil spring pressed together. Compared with the rubber seal, the ceramic seal is more wear-resistant, longer service life, but there are also easy to bruise the hard particles in the coolant defects. Although the water seal processing has been continuously improved, but the water seal damage caused by water pump leakage is still the main reason for damage to the pump. (6) drive pulley According to the transmission belt with different profiles, the drive pulley can be divided into toothed pulley and V-shaped pulley. With fewer and fewer drive belts on the engine, more pumps and generators, air conditioning compressors, and steering booms share the same toothed belt drive, making the toothed belt more and more available. Pump Maintenance In order to make the maintenance of vehicles more efficient, many automotive components are designed to be maintenance-free form, the pump is no exception, the grease filling hole is gradually disappearing from the pump. Even so, the pump in the maintenance process there is still a need to pay attention to. Figure 4 pump and other components sharing drive belt (1) drive belt and pump using the same drive belt to drive more and more parts (Figure 4), in which one of the parts problems will affect other parts. The components driven by the drive belt will generate different frequency vibrations during operation. The vibration is transmitted to the pump shaft through the transmission tape. The long-term abnormal vibration can damage the seal of the pump. Therefore, when inspecting the components such as the pump, you should check the drive Tape other parts, found that the problem should be promptly ruled out. In the installation of the traditional pump belt drive will be related to the tension of the tape, if the tightness of the drive belt properly adjusted, can cause premature damage to the pump. At present most of the engine has been used to adjust the automatic tensioning belt drive, thus reducing the occurrence of similar problems. (2) Coolant The coolant has some lubricating effect on the water seal of the pump. If the coolant loses lubrication due to the high temperature or impurities, it will shorten the service life of the pump. Poor quality coolants may be highly corrosive and must not be underestimated for their ability to corrode the seals on the cooling system. This can cause serious cooling system leaks or excessive water temperatures. Common pump failure In the engine failure, the pump failure to occupy a certain percentage, such as the water temperature is a common engine failure, and a considerable part of the water temperature is caused by the pump failure. In general, the engine's water pump in the use of 100,000 km or so entered the period of high incidence of failure, in order to ensure the maintenance of quality, many of the pump after damage can only take the overall replacement of maintenance, only a small part of the commercial car engine can pump Take a separate replacement bearing or water seal and other parts of the maintenance methods. More and more pumps use camshaft timing tape as the drive belt, and most of the timing tape has a plastic guard outside, so it is difficult to find the hidden trouble of the pump during routine maintenance of the vehicle. trouble. Common pump failure impeller damage, pump leaking and bearing lock. Figure 5 pump impeller cracking (1) impeller damage Impeller damage common forms of impeller cracking (Figure 5), the impeller from the pump shaft or impeller corrosion, impeller corrosion generally does not cause engine failure. After the impeller is cracked or the impeller is loosened from the pump shaft, the circulation speed of the coolant becomes slow, which may easily cause the engine to overheat. The damaged impeller may also hit the pump housing while rotating, causing the housing to crack. Impeller damage is usually due to engine abnormal temperature conditions, and some because of the pump impeller quality problems. Check the impeller is damaged, most of the pump can only be removed after the impeller to see the status of some of the engine can remove the thermostat can touch the pump impeller. (2) pump leakage Pump leaks common parts have water seal leakage and the combination of water pump and cylinder leaking. After the water seal is damaged, the coolant usually leaks from the pump shaft. Some pumps have overflow holes in the pump shaft, its role is to determine whether the water seal leaks and discharge water from the pump. When the water seal is damaged, the coolant will flow out of the overflow hole. If the overflow hole is blocked, the leaking coolant will enter the pump bearing and cause damage to the bearings. Common causes of water leakage at the junction of the pump and the cylinder are damage to the rubber seal of the pump or the gasket between the pump housing and the cylinder mating face. Antifreeze has a certain color and will emit a special smell when heated, so you can work through the engine