We know that many of the auto parts are gear constructions, and these gears are made by powder metallurgy. With the development of China's auto industry and the improvement of energy saving and emission reduction requirements, the application of powder metallurgy technology in the automotive industry. More and more, more and more metal parts will be produced by powder metallurgy. At present, the average powder metallurgy product usage per car in Europe is 14kg, Japan is 9kg, the United States has reached 19.5kg or more, and it is expected to reach 22kg in the next few years. At present, the average amount of powder metallurgy products per automobile in China is only 5-6 kg. Considering the factors of energy saving and emission reduction, domestic enterprises will use more powder metallurgy processes to produce auto parts in the future.
The distribution of powder metallurgy parts in automobiles is shown in Figure 2. Among them, there are shock absorber parts, guides, pistons and low valve seats in the chassis; ABS sensors, brake pads, etc. in the brake system; pump parts mainly include key components in fuel pump, oil pump and transmission pump; engine There are conduits, races, connecting rods, housings, variable valve timing system (VVT) key components and exhaust pipe bearings, etc.; the transmission has components such as synchronous hub and planetary carrier.
With the improvement of energy-saving and emission-reduction requirements for automobiles, in recent years, VVT parts, variable pumps and brake vacuum booster pump parts have been widely developed and applied in these three categories of energy-saving and emission-reduction auto parts.
1.VVT powder metallurgy parts
VVT or VCT (Variable Cam Timing System) adjusts the phase of the engine cam through the equipped control and execution system, so that the valve opening and closing time changes with the engine speed to improve the charging efficiency. , a system that increases engine power. The actuators of VVT or VCT systems—the core components of the phaser, the stator, the rotor, and the end caps are mostly powder metallurgy.
The principle is to adjust the intake and exhaust volume and valve opening and closing time and angle according to the operation of the engine to optimize the amount of incoming air, improve combustion efficiency and reduce emissions. Its advantages are fuel economy and power boost.
In 1980, Alfa Romeo first used VVT technology; in 1989, Honda first used VVT technology with variable valve lift capability; in 2001, BMW replaced VVT with traditional throttle for the first time.
There are different names for the various auto companies in the technology, such as Toyota's VVT-i, Honda's VTEC and i-VTEC, Mitsubishi's MIVEC, Nissan's CVVT, and European and American companies' VCTs, which are different technologies. The actuators of the VVT or VCT system—the core component sprocket, stator, rotor (see Figure 3) and end caps in the phaser are mostly powder metallurgy processes.
The use of VVT technology is in line with the trend of international automotive technology development, namely energy saving, miniaturization, light weight and fuel economy. According to the actual detection of a domestic enterprise, the economical car with a displacement of 1.3L can increase the power of the engine by VVT technology by 4.6% and save fuel by 18.6%.
2. Powder metallurgy parts in the oil pump
At present, most of the engine oil pump and the automatic transmission oil pump use a quantitative oil pump, and the quantitative oil pump is generally an external gear pump, an internal meshing cycloid pump or an internal gear pump. The gears of this type of pump are manufactured using a powder metallurgy process.
3. Powder metallurgy parts in the oil pump
For the quantitative oil pump, the oil output increases with the increase of the engine speed, and the two are linear. In order to ensure the minimum oil output at low speed and the minimum oil pressure at high speed, the oil pump will be designed to be larger, which puts higher requirements on the engine compartment layout. At the same time, when the engine is at high speed, excess oil will return from the oil circuit, resulting in increased engine power consumption. The variable oil pump will adjust the oil pressure and oil quantity according to the working condition of the engine, so as to achieve the purpose of fuel saving.
According to the research data, in the engine with fixed displacement oil pump, when the speed is >2500r/min, about 50% of the power oil directly flows back to the oil pump inlet or oil sump through the pressure relief valve, bringing energy. Waste; the use of variable oil pumps instead of quantitative oil pumps can generally save 2% to 5% of fuel, and CO2 emissions by 1% to 2%.
Variable displacement pumps generally have a type of structure such as an external gear pump, a vane pump, and a vane pump. External gear pump such as Volkswagen's EA888 project, one of which has a fixed axial position of the gear, and the other axial direction of the gear is adjusted with the pressure. When the idling speed, both gears are meshed. When the speed increases, the pressure of the pump also follows. When the pressure is raised, the gear meshing portion of the compression spring is shortened, so that the flow rate of the oil pump can be adjusted at any time. The gears of such pumps are manufactured by a powder metallurgy process.
The vane type variable pump (see Fig. 4) is mainly composed of a stator, a rotor and a vane, wherein the stator and the rotor are both powder metallurgy parts. The vane type variable pump works by adjusting the eccentricity by pressure to adjust the flow.
The principle of the vane type variable pump is basically the same as that of the vane type variable pump, and the eccentricity is adjusted to adjust the flow rate. Its structure is shown in Figure 5a, in which the sliding piece is a steel piece, the intermediate piece is connected to the sliding piece, the outer part is a sliding sleeve, and the middle is a rotor, and these three pieces are powder metallurgy pieces (see Fig. 5b).
4. Brake booster vacuum pump in powder metallurgy parts
Vehicles equipped with gasoline engines, because the engine is ignited, can generate high vacuum pressure in the intake manifold, which can provide sufficient vacuum source for the vacuum assisted braking system. Most of the current vacuum pumps are connected to the intake manifold. At the office. In order to meet the high emission and environmental protection requirements, the gasoline direct injection engine cannot provide the same level of vacuum pressure at the intake manifold to meet the requirements of the vacuum brake boosting system. Therefore, a vacuum pump needs to be installed.
For diesel-driven vehicles, the same level of vacuum pressure cannot be provided at the intake manifold because the engine is pressure-combusted, so a vacuum pump is required to provide a vacuum source. The power of the vacuum pump (see Figure 6) is obtained directly from the engine. The power is driven by the powder metallurgy coupling to drive the powder metallurgy rotor (see Figure 7) and then drive the plastic valve. The rotor and the pump chamber have a certain amount of eccentricity. The rotation of the valve plate generates a vacuum, and finally the brake assisting effect is completed. This type of vacuum pump was developed primarily to meet the high emission requirements of gasoline and diesel engines, and has played a role in reducing emissions.
The above is about the application of powder metallurgy technology in the automotive industry. Whether it is by weight or by the number of parts, the proportion of powder metallurgy gears in automobiles and motorcycles is far greater than that of powder metallurgy parts in other fields. With the development of China's automobile industry and the improvement of energy-saving and emission-reduction requirements, more and more metal parts will be produced by powder metallurgy.