A method of applying two-pump system in automatic transmissions for energy conservation

Abstract

In order to improve the hydraulic efficiency, modern automatic transmissions tend to apply electric oil pump in their hydraulic system. The electric oil pump can support the mechanical oil pump for cooling, lubrication, and maintaining the line pressure at low engine speeds. In addition, the start-stop function can be realized by means of the electric oil pump; thus, the fuel consumption can be further reduced. This article proposes a method of applying two-pump system (one electric oil pump and one mechanical oil pump) in automatic transmissions based on the forward driving simulation. A mathematical model for calculating the transmission power loss is developed. The power loss transfers to heat which requires oil flow for cooling and lubrication. A leakage model is developed to calculate the leakage of the hydraulic system. In order to satisfy the flow requirement, a flow-based control strategy for the electric oil pump is developed. Simulation results of different driving cycles show that there is a best combination of the size of electric oil pump and the size of mechanical oil pump with respect to the optimal energy conservation. Besides, the two-pump system can also satisfy the requirement of the start-stop function. This research is extremely valuable for the forward design of a twopump system in automatic transmissions with respect to energy conservation and start-stop function.

RETRACTED: Generic control flow for the four types of clutch-to-clutch shifts

“…Many researches have been done on the clutch-to-clutch shifts. For the power-on upshift, the slide mode control is adopted by Runde 1 in both torque phase and inertia phase; an open-loop control based on randomized algorithms is proposed by Yoon and Khargonekar; 2 the optimal control based on the cost functions is used by Haj-Fraj and Pfeiffer; 3 Bai et al 4 proposes a hydraulic washout technique to control the synchronization of the oncoming and the offgoing clutches; a robust adaptive scheme with intelligent supervision is used to reduce the shock and prevent an excessive slip by Kim et al; 5 the close-loop control and output torque control are adopted by Goetz et al; 6 the dynamic characteristics of the shift events of DCT are studied by Kulkarni et al; 7 Dong et al 8 investigates the pressure control of clutch for start stop function; and the vibration response during shift is analyzed by Walker and colleagues. 9,10 For the power-on downshift, the shift processes including engine torque control, clutch slip control, and transmission output torque control are designed by Goetz et al; 11 shift control strategy and experimental validation in DCT are studied by Liu et al; 12,13 and the constant output torque control technology based on a power-based integrated powertrain control system is developed by Bai et al 14 In previous researches, they mainly focus on the study of control methods for the torque phase and the inertia phase during the clutch-to-clutch shift process, and the control strategies for the power-on upshift and power-on downshift are often analyzed separately.…”

Optimization design of powertrain mounting system considering vibration analysis of multi-excitation

“…The major contribution of this article is to optimize design methods for determining mount stiffness and considering vibration analysis of multi-excitation under excitation of engine and ground. First, take the front-drive powertrain as the research object [22][23][24] and built the model with rigid body dynamics and energy method. Then, optimize the stiffness of the PMS through calculating and analyzing the decoupling rate and the corresponding modal frequency of PMS.…”

Hardware-in-the-loop validation of speed synchronization controller for a heavy vehicle with Hydraulics AddiDrive System

“…Thus, the core of the SSCS lies in the displacement control of the VDP, which decides the speed of the front wheels through adjusting the swash-plate angle of the VDP. 11 The changing driving conditions demand that the VDP displacement should be controlled in real time to meet actual load requirements. [12][13][14][15] An optimum slip ratio-based proportional-integral-derivative (PID) control algorithm was proposed to adjust the displacement of VDP.…”