Systematic Optimisation of Gearboxes for Hybrid and Electric Vehicles in Terms of Efficiency, NVH and Durability

Transcription

1 Systematic Optimisation of Gearboxes for Hybrid and Electric Vehicles in Terms of Efficiency, NVH and Durability Dr. Artur Grunwald GKN Driveline 1

2 Content of presentation Scope and introduction Gearbox layout and main components Methodology of application development Simulation tools for evaluation Macro geometry optimisation Micro geometry optimisation Experimental evaluation Conclusions and outlook 2

3 Scope of the optimisation Balance gearbox efficiency, NVH and Durability by identifying main contributing design parameters and evaluation of the level of influence. Our goal is systematically to separate the design parameters and to enable biggest benefit at acceptable cost level. 3

4 Introduction Electric vehicle application Front drive gearbox Input torque: 200Nm Max. input speed: 14000rpm Max. input power: 87kW Gearbox weight: Gearbox ratio: < 25kg 9.5 (further options available) SOP: end of

5 Gearbox layout and main components Single speed gearbox Dual stage gear layout Integrated park lock system Low viscosity synthetic oil Ground and powerhoned gears 6 ball bearings & 3 radial sealing devices Two pin open differential assembly Optimised for efficiency, NVH and durability 5

6 Methodology of application development INPUT > Specification > Packaging > Duty Cycle OUTPUT Optimised gearbox design followed by verification & validation Task 1 Layout definition with ratio split, centre of distances, modules, tooth count, initial bearing sizing and sizing of the housing Continues check against knowledge, experience & benchmarking Task 5 Analyse and optimize required micro corrections for balanced durability, NVH and the efficiency Task 2 Balance the life time expectations for gears, shafts & bearings Task 4 Check excitation frequencies & deflection form within modal analysis Task 3 Balance the durability, NVH & efficiency expectations for gearbox 6

7 Simulation tools and evaluation matrix Selective software pool for effective gearbox analysis ISO rating methodology for bearings and gears System and component level capability Collaborative way of working with software suppliers 7

8 Example of applicable simulation tools SABR, GPS & user interface for performance evaluation SABR / GEAR (Ricardo Software) GPS (Dontyne Systems Software) LAM INTERFACE ASCII / USER INTERFACE for further evaluation 8

9 Macro geometry optimisation Systematic variation of Pressure angle Helix angle Gear module Addendum modification Face width Ratio split Axle angles and further features Balancing of relevant features for NVH Efficiency Durability 9

10 Macro geometry optimisation Systematic variation of Pressure angle Helix angle Gear module and further features Examples for results visualization Evaluation of Bending stress Contact stress Bearing damage Bearing power losses Contact ratio 10

11 Micro geometry optimisation Detailed evaluation across the flank and profile of Gear root stress Gear contact stress Investigation across the flank and profile of Specific oil film thickness Contact temperature Power losses in the mesh 11

12 Micro geometry optimisation Transmission Error optimisation TE optimisation due to modification of profile slope, profile crowning, flank slope, flank crowning and others. Experimental verification Experimental verification of gear contact pattern on the bench in the gearbox assembly. 12

13 Experimental evaluation of NVH Drive and coast conditions for gear whine measurements Harmonics of tooth meshing rates during the speed run up Discrete FFT to identify the relevant order Evaluation of vibration amplitude versus speed 13

14 Experimental evaluation of durability Condensed duty cycle fatigue tests Whole gearbox life testing in less than 500h Static and dynamic peak load tests Evaluation of system performance and components 14

15 Experimental evaluation of efficiency Performance evaluation on system level on GKN bench Drive and coast conditions measurements Dynamic calibration of torque cells on the rig Measurements of drag torque at controlled temperatures Example of experimental evaluation at +20 C of system performance at GKN test bench for a reference hybrid gearbox set up. 15

16 Conclusion and outlook GKN Driveline will continue to develop and enhance the product performance to meet today s and future customer demands. Consistent development methodology is enabling us to develop best in class components and driveline systems. We will continue our collaborative way of working with our software suppliers using existing standards and developing methodologies beyond these standards. 16

17 Thank you very much for your interest and your attention! 17