Bus Technology and Research Application of AMT Automatic Shift Transmission in City Bus Lu Yongsheng (Guangzhou Junwei Bus Co., Ltd., Guangzhou 510430, Guangdong) Transmission, Explain its development process, working principle, performance characteristics and its application prospects in urban passenger cars .
1Automatic transmission speed governor and AMT CVT continuously variable transmission have limited transmission power (limited to 135N.m or less), the clutch is unstable, and the entire transmission mechanism loses a large amount of power. It has not been generally accepted by the automotive industry.
The AT automatic transmission, although its fueling speed (fueling amount) and engine operating conditions are better than the MT manual mechanical transmission, can reduce the fuel consumption of the engine, but the transmission efficiency of the torque converter is lower than the mechanical transmission efficiency. Therefore, its overall working oil consumption is still higher than that of a manual mechanical transmission. Due to the frequent starting of the city bus and the high labor intensity of the driver, the automatic transmission is convenient and simple to operate, and the fatigue strength of the driving can be greatly reduced. Therefore, the use of the automatic transmission in the city bus is increasing day by day.
The AMT automatic shifting transmission has simple structure, easy maintenance, convenient maintenance, low fuel consumption and low input cost. The use rate in the past two years is faster than that of the automatic transmission. However, if it is improperly controlled at the start, it will have an impact. It is mainly used in trucks and road buses. As the technology of automatic shifting mechanical transmissions matures, it will enter the urban bus system and replace the automatic transmission.
2AMT development process AMT, fully automatic AMT, intelligent AMT and other stages, developed to date, to the overall control stage - AMT and engine control computer matching, mainly used in trucks and road passenger cars. The representative models are mainly the Italian "Iveco" Stralis tractor (with the German ZF company's 16-speed Eurotronic automatic transmission), the German), the Swedish "Volvo" FM and FH series trucks (with the Volvo's IShift automatic transmission) , Sweden's "Scania" P114GA tractor (equipped with Scania's Opticruise 12-speed automatic transmission) and so on. Companies mainly engaged in the development and production of AMT technology include Germany's Getrag and ZF, USA's Eaton and Allison, Sweden's Volvo and Scania. .
At present, about 400,000 vehicles in Europe are equipped with automatic shift transmissions, and the usage has gradually evolved (see the European Demand Comparison Table). It can be seen from Table 1 (the amount of AMT vehicles used in 1997 is 1), and the usage of AMT products is rising. The use of AT/CVT products is also rising, but its average growth rate is decreasing. The use of MT products has declined.
AT/CVT, AMT demand comparison table AMT automatic shift transmission appeared in the 20th century 60~70 AMT1997*1999 started, 1999*2003 is the age, the initial listing in the mid-to-late 70s. AMT has experienced a semi-self-long-term growth and its growth rate is relatively fast. 2003*2006 is a perfect period for the design and calculation of AMT. Due to the lack of application in urban buses, its growth rate is relatively slow. It is estimated that 2006 is a turning point. After the products are maturely applied to city buses, the number of vehicles using AMT will increase rapidly. AT/CVT is growing continuously, but its growth rate is decreasing (the average growth rate in 1997-2001 is 16%, the average growth rate in 2001-2003 is 14% 2003-2004 growth rate is 11% estimated 2004- The average growth rate in 2007 was 8%).
The number of vehicles using MT vehicles reached its peak in 1999, and then began to decrease year by year.
In China, Shanghai, Beijing, Nanjing and other places and Dongfeng Motor Corporation have research and development of AMT. Take Shanghai Yingdaxin Company as an example. In 1990, Yingdaxin Company applied for 27 AMT series patents and a software copyright, and passed them in SUV, Samsung Haiba van, Santana 2000 sedan, and military high. SUV and Guangzhou Junwei Bus Co., Ltd. GZ6120S low-entry city bus and other products. AMT is now in an intelligent stage. The development of China's AMT technology is waiting for the joint efforts of domestic research and development units, automobile manufacturing enterprises and bus companies.
3AMT working principle AMT automatic shift transmission (electromechanical shifting technology) is automatic shifting by electronically controlled mechanical shifting. It is based on the traditional mechanical transmission and dry clutch, applying electronic fuzzy control theory to achieve clutching. Coordinates movements with selected shifts to achieve full automatic shifting during driving.
The automatic shift transmission utilizes various types of sensors to simultaneously transmit engine operating conditions (power and speed), such as vehicle speed, throttle, brakes and roads, to the electronic processing unit (ECU), and analyzes the signal source via the ECU. Processing, and then issue instructions, so that the hydraulic actuator (the stepper motor actuator used on the small car) completes the corresponding action at the appropriate speed at the appropriate time, coordinates the two mechanical actions of the clutch and shift, and realizes the automatic change. Gear shifting.
The car's automatic shifting transmission system is an automatic control system that integrates electronics, mechanics and hydraulics. It is composed of ECU data processing system, signal acquisition system, hydraulic execution system, shift selection control mechanism, throttle execution control mechanism and brake execution control mechanism with original mechanical transmission and dry clutch. The working principle is that the ECU data processing system compares, processes, and memorizes the signals collected by the signal acquisition system, and is the core of the automatic shifting shifting system.
The signal acquisition system includes a throttle sensor, a speed sensor, a brake state sensor, and a throttle sensor. The signal is collected and transmitted to the ECU data processing system via the CAN bus.
The hydraulic actuator system includes a power source consisting of a power oil pump, an accumulator, a cooler, and a filter, as well as a shift selector actuator and a clutch actuator. According to the instruction of the ECU, the shift actuator and the clutch actuator are selected to perform the coordinated action of the shift selection and the clutch.
The shift control mechanism is installed on the right side of the driver. According to different driving requirements, the gear position is adjusted to neutral (N), reverse (R), forward 1 (D1), forward 2 (D2), and forward 3 ( 3) and advance 4 (4). Depending on the road conditions, the car can be forced in 1st gear (D1), 2nd gear (D2) and full gear automatic shifting (4).
The throttle execution control mechanism collects the throttle signal, and after being processed by the ECU, according to the instruction of the ECU, the throttle is coordinated with the road condition and the gear position at the optimal position, so that the vehicle operates under the optimal state of power and economy.
The brake execution control mechanism collects the brake signal and transmits it to the ECU, and the ECU issues an instruction to coordinate the movement of the shift, the clutch, and the vehicle speed (throttle).
Advantages and Disadvantages of 4AMT Compared with automatic transmission, AMT automatic shift transmission has the advantages of simple structure, easy manufacture, convenient maintenance, low fuel consumption and low input cost. Compared to the automatic transmission, the flexibility at the start is insufficient.
The ECU system of the automatic shifting shifting system perfectly coordinates the four mechanical actions of oil supply, clutch, gear shifting and braking (the torque converter + planetary gear system of the automatic shifting system, the fueling rate, time, clutch) And the selection of shifts into one). The current automatic shifting system uses mechanical refueling. At the beginning, the coordination of fueling rate and time and clutch is the key to the coordination of the four mechanical actions of “oil supply, clutch, gear shifting and brakingâ€. The start, fueling rate and time of the automatic shifting shifting system depend on the driver's operation to coordinate with the clutch.
Improper driver operation can cause an impact when the car starts. The automatic shifting shifting system is more compliant, and like the mechanical transmission system, it basically relies on the driver's proficiency; therefore, the city bus driver is not easy to accept. This is the biggest gap between the automatic shifting system and the automatic shifting system.
From the structure of the automatic shifting shifting system, it can be seen that the actuator of a hydraulic torque converter + planetary gear system is much simpler than the actuator of the automatic shifting system, so its manufacturing and maintenance design calculation research passenger car technology and Research and maintenance are easier and more convenient than automatic transmissions and can be modified by mechanical transmissions. Therefore, its input cost is much lower than that of an automatic transmission system.
One of the actuators of the automatic transmission system, the transmission torque is only 83% and the mechanical transmission efficiency is 98%, although the automatic transmission system's fueling speed (fueling amount) is better than the engine operating condition. Reduces engine fuel consumption, but its transmission efficiency is low, and the overall working fuel consumption is still higher than the mechanical transmission system.
The matching speed of the automatic shifting transmission system and the engine operating condition is similar to that of the automatic transmission system, and the mechanical transmission efficiency is 98%, so the automatic shifting shifting system is more fuel-efficient than the automatic shifting system.
Compared with the mechanical transmission system, the automatic shifting shifting system has the advantages of simple operation and reduced labor intensity of the driver. The disadvantage is that the input cost is large; the start of the smooth driver needs to have a re-familiar process.
The characteristics of urban public transport are: low speed and overload, slowdown, clutching, shifting, starting and accelerating frequently. According to statistics, the average number of passengers on the bus is about 2,000 to 3,000 times per day. Every day, the left and right feet move simultaneously, coordinate the clutch and accelerate, the driver's labor intensity can be imagined, the automatic shifting shifting system will shift, shift and accelerate into automatic shifting, which can greatly reduce the driver's labor. strength. However, the automatic shifting system is used at the current stage, and the driver needs to control the fueling rate and the coordination of the time and the clutch by the right foot. Although this coordination is different from the mechanical transmission system, the driver's adaptation takes a while; and the driver needs By adjusting the fueling rate and the coordination of the time and the clutch by the right foot, it is necessary to achieve a high level of concentration in order to achieve the smooth start of the car. Compared with the automatic transmission system, the usage rate of the automatic shifting transmission system in urban public transportation is currently difficult to improve.
5AMT application prospects in urban public transportation China's automatic transmission technology is seriously behind the world level. At present, there is no transmission manufacturer with independent intellectual property rights of automatic transmission system. Foreign automatic transmission technology is confidential to China. The introduction of an automatic transmission system production line is costly. The technical features of the automatic shifting transmission system are simple structure, low cost, high transmission efficiency, fuel saving, convenient maintenance, and can be modified on the manual transmission. However, its fuel consumption is high, maintenance is troublesome, and the cost is high. The bus company can afford it and it is difficult to raise it. This is the advantage of the automatic shifting transmission system. There are many mechanical transmission manufacturers in China, and the automatic shifting and shifting technology has independent intellectual property rights and is in the stage of industrial transformation. The application prospect of the automatic shifting shifting system on urban passenger cars is broad.
Speeding up the application of the automatic shifting shifting system in urban passenger cars, the bus company is now required to deepen its understanding of the automatic shifting shifting system. Although the automatic shifting shifting system is difficult to grasp at the start than the automatic shifting system, it is not difficult to grasp the automatic shifting shifting system like the mechanical shifting system when starting the vehicle. China's current automatic shifting transmission system is safe and reliable. The driver's labor intensity is lower than that of the mechanical shifting system. Its fuel consumption is lower than that of automatic transmission and mechanical transmission.
To speed up the application of the automatic shifting shifting system in urban passenger cars, the research and development unit should upgrade the current automatic shifting shifting system to a grade, and use the electronic throttle to transform the manual control of the fueling rate and time and clutch coordination into the ECU. The program is controlled so that it is as flexible as the automatic transmission system at the start. This will be more popular with bus companies.
6 Conclusion The research and development of China's automatic shifting technology is different from that of foreign countries. Foreign research and development is affiliated to the research and development department of large automobile companies, and its research results are generally tested by subsidiaries of the company.
The research and development unit of China's automatic shifting and shifting technology is an independent legal person. The automatic shifting and shifting technology is transformed into productivity, and the technological progress of the passenger car industry in China is accelerated. It requires the bold trials of automobile manufacturers and the bold trials of bus companies. In addition, it is hoped that relevant government departments will adapt to the characteristics of China and formulate development policies and regulations that are conducive to promoting China's automobile industry to promote the advancement of independent technologies in China's automobile industry.
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