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Starting from the real vehicle working conditions and taking that engine works at the optimum economic line as a foundation, this paper gives the power transmissive principle of hybrid vehicle with energy storage flywheel working in process of accelerating, uniformly running and braking, derives the relationship of the ratio and time in continuously - variable transmission(CVT) under working conditions of adjusting engine load, recovering and releasing energy etc., and provides the theoretic foundation for transmission system of flywheel energy storage vehicle to realize optimum economic control.

The paper details an analytical redundancy fault diagnosis method of automated mechanical transmission (AMT) control system. The basic principle of AMT is depicted. After concisely introducing the models of engine, gear box and clutch, which are used to provide redundant information, the diagnostic logic is illustrated in detail. The information redundancy in the local models of the powertrain and the structure logic relations among the assemblages is used to detect and diagnose the faults of the sensors, the actuators and the unit assemblages of the AMT system. The fault codes and fault process measures are listed out.

The main objective of designing the powertrain mount system is to decrease the vibration transmission from the powertrain to the body. The powertrain mount system has enormous effect on the ride comfort of the automobile. The reasonable design of powertrain mount system could not only decrease greatly vibration and noise produced by engine, but also could lengthen the life of the parts. Therefore, it is very important that design of powertrain mount system. The purpose of this paper is to develop an analytical optimum software to assist the design engineer in arriving at a mounting configuration with the most potential to achieve all the desired performance goods without violating size of the engine compartment. 6 DOF (Degree of Freedom) nonlinear mechanical model of powertrain hydraulic mount system is set up. The hydraulic mount''s position, orientation, stiffness and damping are considered as the optimum variables.

A novel hydraulic transmission system-Hydraulic Energystorage Transmission System(HESTS) which contains a Hydraulic Continuously Variable Transmission(HCVT) and a flow controllable accumulator is proposed. The power flows of the HESTS has been analyzed. Computer simulations show the potentialities of improving fuel economy of a vehicle with a HESTS. A fuzzy logic controller with two regulating factors is developed to improve the performance of the HESTS with variable loads.

In View of the performance of high output torque moment, good response and continuously variable transmission of hydrostatic transmission, a new concept of Hydraulic Energy Storage Transmission System (HESTS) of city bus was put forward, although the hydraulic-mechanical split power hybrid city bus had run effectively in some cities, such as Copenhagen, Stockholm and Berlin, etc.[1][2]. HESTS was comprised of a variable displacement pump, a variable displacement pump/motor unit, two accumulators and an Electrical Control Unit (ECU). The high pressure accumulator could be controlled to absorb braking energy in hydraulic energy and reuse the stored energy to restart the prime mover or accelerate the vehicle. HESTS could operate in seven modes while the ECU outputs different combined control signals to pump, pump/motor and directional valves. The mathematical model of a HESTS for a city bus was established.

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 working principle of hydraulic branch of the hydromechanical transmission is introduced, dynamic characteristic analysed, its actuating medium enclosed in the working space consists that of pump, soft pipeline and motor considered to be a torsional hydraulic spring whose torsional stiffness and damping provided. The multidegrees-of-freedom of the concentrated mass-elasticity discrete mechanics model is utilized to analyze the transmission system, and the finite element method is employed to model it, the torsional natural characteristic of the system are calculated, these provide the scientific basis for structural modification of controlling the vibration and noise.

A systematic analysis method of the mechanism and simulation of self-excited vibration in the transmission is proposed. The fact that there is self-excited vibration with hard excitation characteristics in the vehicle transmission at high slip rate is observed by analyzing the results of the experiments. The cause of the self-excited vibration is found by means of the phase plane analysis and the vibration energy analysis approach. A 21-degree-of-freedom variable parameter model of the vehicle torsional vibration is established to simulate the nonlinear vehicle feedback-control system of the self-excited oscillation. A good agreement is shown by comparing the predicted results with measured ones.

The paper introduces an on-board fault diagnosis strategy based on analytical redundancy suit for automated mechanical transmission (AMT). Through experiment and theory analysis an identified engine model, a gear box model and a dry clutch model controlled by hydraulic actuators are respectively established. The information redundancy in the local models of the power train and the structure logic relations among the assemblages is used to detect and diagnose the fault in the sensors, the actuators and the unit assemblages of the AMT system. The method has been used in the AMT control system developed for the SVWSANTANA2000.

The control of vehicle clutches is somehow different of non-linearity from others and needs consideration of control matching between the clutch and engine. For that reason, an expert fuzzy control is proposed in this paper, which is integrated with expert control, fuzzy control and hierarchical control. By real vehicle test results, the control function is verified.

Hydraulic retarder, as an auxiliary braking device, is widely used in commercial vehicles. Nowadays, the hydraulic retarder’s internal oil is mainly cooled by the coolant circuit directly. It not only aggravates the load of engine cooling system, but also makes the abundant heat energy not be recycled properly. In this study, an independent energy supply device with organic Rankine cycles is applied to solve the problems above. In the structure of this energy supply device, the evaporator’s inlet and outlet is connected in parallel with the oil outlet and inlet of the retarder respectively. A part of oil enters the evaporator to transfer heat with the organic fluid, and the rest of oil enters the oil-water heat exchanger to be cooled by the coolant circuit. According to the different braking conditions of the retarder, the oil temperature in the inlet of the hydraulic retarder can be kept within the proper range through adjusting the oil flow rate into the evaporator properly.