Search Results

The use of hydrodynamic transmission with lock-up clutch for a Chinese city bus leads to good fuel economy and ease of operation. Many examples have shown that the microprocessor-based control system used in a vehicle powertrain has the advantage with high control speed over a manual one, but most of the time, its control qualities are poor, especially when outside conditions change. In this paper, a synthetic control method for hydrodynamic transmission for a Chinese city bus is proposed with respect to control qualities of lock-up control. The lock-up control process is divided into two steps, i.e., ‘estimate’ step and ‘fine’ step, so we can apply different control schedules to realize different control demands and get better control qualities.

A newly developed GYB-100 hydrodynamic transmission consisting of DFZFB-323 torque converter with lock-up clutch and power shift gearbox for Chinese city bus has been put into operation. The locking-up process of the torque converter is a transient one, and it will bring great shudder to powertrain and thus reduce the lifespan of the clutch. Measures must be taken to eliminate the shudder. In this paper, the city bus powertrain is supposed to be a concentrated mode, i.e, a spring-mass system having multi-degrees of freedom. From analysis of dynamic characteristics of the lock-up clutch it gives that the friction characteristics of the lock-up clutch are of main importance for avoidance of shudder and the proper control of oil pressure operating the lock-up clutch and oil-filling time will lead to improved friction characteristics. The judgement of quality of the lock-up clutch is presented. Using modern control theory, we get optimal control schedule of the lock-up clutch.

In this paper,the flywheel is considered to be linear elastic composition in accordance with its operating characteristic, mechanical and mathematical model are presented,the finite element method is employed to carry out the numerical analysis of steady and unsteady stresses within the high speed flywheel in the regenerative braking system of a city bus,and these provide the basis foŕ its structural modification and further rational design.

The city buses start and stop frequently, therefore significant amount of kinetic energy is wasted on friction plates. In order to retrieve this amount of energy, various feasible and efficient energy storage systems have been suggested by researchers to reuse the energy to improve the efficiency of the city bus. Due to small size, high energy density, cleanliness and easiness to absorb/reuse the energy, the storage system of flywheel is hopeful to be coming into wide use. In this paper, a dynamic model is analyzed to study the characteristics of the system using time series. Finally, comparison between simulation and experiment is given.

In this paper, the powertrain of passenger car is supposed to be a concentrated parameter model with its inertia neglected, the transfer function of the system is deduced, the relationship of natural frequency between hydromechanical and mechanical & hydraulic system is revealed, and several measures to increase values of powertrain freqency are proposed. Finally, the computer calculated result of dynamic characteristics of the powertrain is given.

In this paper, a quasi-three-dimensional design method of torque converter blade is presented, and a turbine example is designed. In addition, a new way that three-dimensional flow field calculation is added into traditional blade design is given and the judge rule of flow field is presented. The blade system of a Chinese made YB 300 torque converter has been redesigned with the aid of the new way, and its performance has been improved. The experiment shows that the maximum efficiency has been raised from original 84. 7% to 86%, with other factors such as stall torque ratio and so on unchanged or a little better.

A SRM* type torque converter and power shift gear box were designed and trial-produced for Chinese city bus, considering the cost of manufacture as the first factor. The SRM type torque converter used in this transmission was independently developed and tested in China with very good results. The combination of SRM torque converter with lock-up clutch and two forward speeds including one overdrive speed has made the Chinese city bus perform better in fuel economy, gradeability, ease of handling and in start quality than the conventional mechanical gear box.