Georgia Institute of Technology Marquette University Milwaukee School of Engineering North Carolina A&T State University Purdue University University of California, Merced University of Illinois, Urbana-Champaign University of Minnesota Vanderbilt University Modeling and Experimental Testing of the Hondamatic Hydro-Mechanical Power Split Transmission Xiaodong Hu, Zhejiang University Visiting PhD student at UMN Dr. Chongbo Jing, Beijing Institute of Technology Visiting Scholar at UMN Prof. Perry Y. Li, University of Minnesota
Motivation Hydro-mechanical Power Split transmission (HMT) combines the advantages of mechanical (efficient) and hydraulic (adjustability) transmission Traditional HMT is complex; requires planetary gear-set Hondamatic transmission achieves power split without planetary mechanisms pump motor Servo motor Hondamatic screw and ball Hydrostatic Transmission Traditional HMT Very compact (30cm),22kW
Outline Motivation Operating principle of Hondamatic Modeling Simulation Results Experimental Results (preliminary) Conclusions and next plan
Operating Principle The engine power drives the pump casing The pump swash plate rotates, makes the pump play the role of a planetary gear. pump Servo motor motor screw and ball Hondamatic symbol Fixed displacement wobble plate pump with rotating barrel Variable displacement motor Pump and motor are connected both mechanically and hydraulically The ratio of the power split and overall transmission can be adjusted by varying the motor displacement
Ideal Transmission Ratio Dm = [-0.9cc,18cc] Dp = 6cc Ratio : The theory range of ratio : 0.85 ~ 4 Mechanical transmission Tme= Ti High pressure Ti nin Tp=Ti np= ni-no + - P Hydraulic transmission Low pressure M Th y nm= no + + To=Ti+TM no nme= no
The Method of Modeling Wobble plate pump Distributor valve Variable Piston Motor Input torque Pump speed + Swash plate speed Pump Model - Pressure Flow Pump torque Barrel speed Pressure dynamics + + Barrel Inertial dynamics Pressure Flow Motor torque Barrel speed Motor model - Load torque Motor displacement
Wobble Plate Pump The torque equilibrium equation of the swash plate: The equilibrium equation of the pistons: The torque equilibrium equation of the barrel: is the mechanical transmission torque.
The axial piston motor The torque equilibrium equation of the barrel: the hydraulic power transmission torque is the mechanical transmission torque The equilibrium equation of the pistons:
Distributor Valves High pressure side Pump casing Low pressure side Distributor valves High pressure side Fixed Motor casing Low pressure side Pump barrel Piston chambers Motor barrel Pump casing and barrel rotate at different speeds with an eccentricity Motor casing is fixed while the barrel rotates Distributor valves move in and out radially as barrel rotates Less leakage and friction than valve plate
The power losses Valve friction losses: Depending on the charge pressure, input and output speed Key parameters: Piston and chamber gap: c_p &c_m Friction coefficient: C_f Two Bearing coefficient: Ka & Kr Oil bulk modulus: E Bearing losses of motor : Reactive force between swash plate & pistons Output speed Oil viscosity Bearing losses of pump: Reactive force between swash plate and pistons The difference of input and output speed Oil viscosity Oil compressibility losses Pistons and cylinder chamber losses, Leakage losses: Couette flow & Poiseuille flow Friction losses: Piston and chamber friction Couette & Poiseuille frictional force
The Simulink model of Hondamatic Simulates output and dynamic characteristics of Hondamatic
Simulation results Input parameters: Barrel and load inertia: Input speed: 3000rpm Load torque: 100Nm Transmission ratio: 4 In ideal mode, output parameters: Output speed: 750 rpm Input torque: 25Nm High pressure: 260bar
Simulation results Input parameters: Barrel and load inertia: Input speed: 1500rpm Load torque: From 120 to 30Nm Transmission ratio: From 4 to 1
Simulation results Input parameters: Barrel and load inertia: Input speed: 3000rpm to 1500rpm Load torque: 100Nm to 50Nm Transmission ratio: 4 The model follows variable speed and torque well The dynamic process is stable
The test bench The purpose of the test bench: I. Measure efficiency II. Identify the model The diagram of the test bench Hondamatic Dynamometer Prime mover Hondamatic testing box
Preliminary experimental results Volumetric efficiency: Mechanical efficiency: Overall efficiency: The volumetric and mechanical efficiencies are similar to the hydrostatic transmission, which is reasonable;
Conclusions I. Established a model for further analyze Hondamatic II. Built a test bench to measure the efficiency of Hondamatic, carried on preliminary experiment Next plan 1. Continue to test, acquire more data, drawing the efficiency map of Hondamatic; Analyze the no-load losses at different input speed; Expanding the scope of the test, measure the efficiency under high speed and torque; 2. Use the experimental data to identify the model; 3. Use the identified model to analyze the dynamic characteristics of Hondamatic ; 4. Discovery some new applications for Hondamatic;