Marvin Paul Kraska

Dynamic modeling of a variable force solenoid and a clutch for hydraulic control in vehicle transmission system

A control oriented solenoid and clutch model for a passenger car automatic transmission is presented. The model captures the essential dynamics of the variable force solenoid and clutch circuit, which operates on a given pressure range commanded by transmission shifting signal. Based on the hardware design parameters and experimental measurements, a nonlinear low frequency model is developed using SIMULINK/sup MT/. The model simulates the key phenomena of the component, such as pressure filling and stroking of the clutch during engagement. Comparing to the first principal models described in other publications, the simple structure and closed form of this model provides a computational test bench for control analysis. The model is validated against the data obtained from a FORD modified CD4E transaxle and the comparison shows a good agreement. The nonlinearity and the time delay presented in the model suggests that a controller other than conventional PID should be considered when designing the control strategy.

Incorporating an electric machine into the transmission control of ford's modular hybrid transmission

Ford recently introduced an industry first Modular Hybrid Transmission (MHT) in the Model U concept vehicle at the 2003 North American International Auto Show. The MHT is a full function hybrid system (i.e. capable of electric drive) that utilizes a modular approach to leverage high volume conventional driveline components to create a lower-cost hybrid system [1]. In the MHT, the torque converter of a conventional automatic transmission is removed and in its place is packaged a single high voltage electric machine and an engine disconnect clutch. Advanced controls are used to enable hybrid functions. A critical element in the development of the MHT is the ability to replicate the functions of the torque converter without compromise to the vehicle drivability. In this paper, the control of four transmission functions in the MHT will be discussed: 1) transmission engagement, 2) vehicle launch, 3) power-on up-shift and 4) coast downshift. Data from test vehicles will be presented that demonstrates the ability of the MHT to meet the drivability requirements of todays production automatic transmissions.