Power Matching Research Of Parallel Hydraulic Hydrid Vehicle

Along with the development of the car industry and the drain of petroleum resources, the increasing of energy and environmental problem has been drawing more and more attention of human beings to the urgent requirement of the low energy consumption and low emission green motors. The rapid development of vehicle technology brings a great opportunity to energy saving and the reduction of pollutant emission, which includes electric vehicle technology, fuel cell electric vehicle technology, hybrid electric vehicle technology, hydraulic energy saving vehicle technology, etc.Hydraulic hybrid vehicle adopts the hydraulic accumulator as the energy storage element and the hydraulic pump/motor as the energy conversion element. Hydraulic hybrid vehicle makes full use of the advantage of hydraulic accumulator in high power density and rapid dynamic response by recovering the braking and inertial energy to meet the intermittence and high power requirement in the starting and accelerating process of vehicle. Hydraulic pump/motor can works in the four torque-angle quadrants (as a motor to drive the load and as a pump to decelerate the load), which has advantages in easy realization of positive inversion, high maneuverability and high reliability. According to certain energy recovery strategy, Hydraulic hybrid vehicle recovers the braking and inertial energy and releases the energy in starting and accelerating process. This design has a dramatic effect on improvement of the fuel economy and reduction of emission, etc. Hydraulic hybrid vehicle technology has gain a wider application in large vehicles and frequent start-stop cases, such as heavy trucks, transporters, and urban buses, etc.This paper originates from the Jilin S&T Bureau Fund project-'The application research on the secondary regulation technology in hydraulic energy saving vehicle' and the school-enterprise cooperation project-'The development of concrete mixing truck based on the hydraulic energy saving technology'. The main content of this paper is that through the optimization of vehicles and components parameters constitute energy control strategy based on logic threshold method to improve the fuel economy and reduce emission on the base of ensuring the braking efficiency and comfort. Vehicle mathematical mode and simulation model were established. A simulation test bench is developed to validate the correctness of the theory analysis, simulation analysis.The major research work of hydraulic hybrid vehicle in this paper includes the following aspects: First analyze the working principle of parallel hydraulic hybrid vehicles, and briefly describe energy control strategy under the start, uniform speed, acceleration, deceleration and braking condition; through comparative axis configuration and single configuration power transmission structure, choose the axis power transmission structure as the transmission structure of hydraulic hybrid concrete mixing truck; According to the hydraulic hybrid system control rules, combined with the vehicle actual condition to determine the selection principle of dynamic components; Vehicle mathematical mode and simulation model were established; Use simulation software AMESim to establish AMESim hydraulic hybrid system model, including: engine system model, hydraulic power system model.Research the control strategy of hydraulic hybrid vehicles power matching, combined with the analysis of the degree of hybrid vehicles, constitute the energy control strategy based on logic threshold. Real-time control energy distribution of hydraulic hybrid system, achieve different operating modes of Hybrid system and dynamic switching between modes; Research the method for determining optimal working curve and efficient work area the upper and lower limits, based on the engine speed; Use AMESim software to build the simulation model of control strategy, including engine control model, the hydraulic pump/motor control model, etc.Use AMESim and VB to establish the united simulation platform (AMEVT), using the powerful computing capabilities, and modeling and simulation of AMESim simulation software and the developing Windows applications ability of VB6.0 software. AMEVT separates the building of simulation models and simulation test analyzed, to improve the efficiency of design simulation. AMEVT is better than AMESim software in processing simulation data.Based on the Established hydraulic hybrid system simulation model, analyze the impact of hydraulic accumulator volume and initial pressure and the set pressure, hydraulic pump/motor displacement, vehicle inertia, the engine power enter on vehicle performance, such as power, comfort, energy efficiency, etc.To validate the correctness of the theory analysis, simulation analysis, a simulation test bench is developed to study experimentally starting performance of the vehicle and braking energy recovery.