Energy Efficiency of Automobiles A Pragmatic View

Transcription

1 Energy Efficiency of Automobiles A Pragmatic View Bob Lee Vice President Powertrain Product Engineering Chrysler Group LLC IEEE Vehicle Power and Propulsion Conference Dearborn, Michigan September 9, 29

2 IEEE Space 2

3 Outline Energy efficiency space Fuel economy and energy efficiency Where does the energy go Fuel economy ideal function Pragmatic energy efficiency improvement model Summary 3

4 Energy Efficiency Space 4

5 What is Efficiency? The dictionary defines efficiency as: The ratio of the effective or useful output to the total input in any system The ratio of the energy delivered by a dynamic system to the energy supplied for its operation 5

6 What is Energy Efficiency Take the Stairs Be More Energy Efficient 6

7 The Physics: Converting Fuel Energy to Work Fuel Economy generally refers to how much distance a specific vehicle can be moved from A to B with a given volume of fuel. Fuel Efficiency generally refers to how well the energy of the fuel is converted into useful work. F aero F tire F brake Mg F trac Laws of Physics Force = Mass x Acceleration Torque = Inertia x Angular Accel Conservation of Energy 1 st Law of Thermodynamics Lower Heating Value of Fuel Work = Force x Distance and so on FEC (Highway) Drive Trace Mph Fuel Economy = 28.6 mpg Time 7

8 Key Fuel Economy Metrics Fuel Economy Labels Regulatory requirement, but also used competitively (can be advertised) Administered by EPA with Manufacturer self certification Consumer Reports Competitive testing by highly influential Independent 3 rd party Cannot be advertised Chrysler strategic objective is to be top quartile in each segment Corporate Average Fuel Economy (CAFE) Fleet mpg average, administered by NHTSA European Union Fuel Consumption Expressed as Liters/1 Km on unique New European Driving Cycle (NEDC) Homologation testing conducted by Manufacturer with an EU approved witness Widely reported (German Auto Motor und Sport is similar to Consumer Reports) and can be advertised CO 2 Emissions (Greenhouse gas pollutant ) Inversely proportional to mpg fuel economy (directly proportional to fuel consumption) for a given fuel. Expressed as gm/mi or gm/km Voluntary fleet average agreement exists between Manufacturers Association (ACEA) and the European Union 8

9 Key Metrics & Cycles Fuel Economy Labels EPA City and Highway label values are calculated as weighted combinations of 5 key tests. They are posted on the new vehicle s window label along with a competitive segment position. The city, highway and cold city cycles feature light engine loads and mostly low vehicle speeds. FTP City Drive Cycle 57 mph HWFET Highway Drive Cycle 6 mph 81 mph US6 High Speed Drive Cycle SC3 Air Conditioning Drive Cycle 2 F Cold City Drive Cycle 55 mph 57 mph The FTP City and HWFET Highway are also combined into an EPA unadjusted value for use in CAFE 9

10 Energy Supply from Internal Combustion Engine Only about 1/3 of the fuel energy is converted by the internal combustion gasoline engine into vehicle work. Advanced gasoline engine technologies (and diesels as well) are aimed at improving the efficiencies and reducing the losses associated with the other 2/3 of the energy available. To Work Losses 1

11 Where the Vehicle Energy is Spent in City Driving Most of the fuel energy on a city type cycle is consumed by (repeatedly) accelerating the mass (weight) of the vehicle, but other vehicle demands & losses take energy also. 11

12 Where the Vehicle Energy is Spent in Highway Driving Most of the fuel energy on a highway type cycle is consumed overcoming the aerodynamic drag of the vehicle, but other demands & losses take energy as well. 12

13 Energy Supply and Vehicle Demand The Physics: Fuel Economy is a function of the total vehicle system, comprising both energy supply in the propulsion system and energy demand of and from the vehicle. Improving it thus requires a total vehicle solution. Energy Supply (Conversion Efficiency and Losses) Thermal Efficiency (Comp Ratio) Combustion Efficiency Heat/Mass Loss Pumping Work Mechanical Friction Technologies Energy Demand (Vehicle Loads, Efficiencies, and Losses) Variable Compression Ratio Direct Injection Downsizing & Pressure Charging Variable Valve Lift/Timing Multi Displacement Sys (Cyl Deact) Diesel Hybrid (Regen Braking, E drive) Fuel Cell Weight Aero Drag Road Loads Accessory Loads Drivetrain Losses Design Technologies Design Technologies Design Technologies Design Technologies Design Technologies Vehicle Size Material Substitution Weight Optimization Loads / Duty Cycles Frontal Area / Height Drag Coefficient Front End Sealing Belly Pans/Fairings Grille Shutters Rolling Resistance Brake Drag Bearing Drag Electric Pwr Steering Var Disp Compressor Electrical Load Mgmt LED tail lights Var Speed Fuel Pump Radiator Sizing Var Speed Fan Reflective Coatings Torque Converter Dual Clutch Trans Cont Variable Trans Axle/ Lube Front Axle Disconnect Wheel Size (Inertia) 13

14 Road Load Subsystem Contributors 4 35 Aerodynamic Transmission/Driveline Hubs/Bearings 3 Brakes Road Load Power [hp] Tires P225/55/R19 Kumho Solus KH16 EPA City Average Speed 21 mph EPA Combined Average Speed 33 mph EPA Highway Average Speed 48 mph CR Highway Average Speed 65 mph Data Source: Chrysler LLC, Dept. 73 Vehicle Speed [mph] 14

15 Pragmatic Efficiency Improvement Model Driver Customers Regulations Competition Suppliers Energy Cost Vehicle Energy Demand Transmission / Driveline Matching Electrification (HEV, ReEV, BEV) Engine Improvement Overall Objectives Improve fuel economy Refinement Cost and complexity reduction Competitive performance Priority: Best Bang for Buck Gains in propulsion efficiency are best built upon reduced vehicle energy demand, as it maximizes the impact of transmission matching and allows engine size and technology to be optimized. 15

16 Pragmatic Efficiency Improvement Model Driver Customers Regulations Competition Suppliers Energy Cost Vehicle Energy Demand Transmission / Driveline Matching Electrification (HEV, ReEV, BEV) Engine Improvement Overall Objectives Improve fuel economy Refinement Cost and complexity reduction Competitive performance Priority: Best Bang for Buck Gains in propulsion efficiency are best built upon reduced vehicle energy demand, as it maximizes the impact of transmission matching and allows engine size and technology to be optimized. 16

17 Transmission and Driveline Efficient and Light Weight Axle Technology Technology Fuel Efficient Rear and Front Drive Units for Pass Car & SUV Open diff, LSD, elsd Benefits Products 17

18 Pragmatic Efficiency Improvement Model Driver Customers Regulations Competition Suppliers Energy Cost Vehicle Energy Demand Transmission / Driveline Matching Electrification (HEV, ReEV, BEV) Engine Improvement Overall Objectives Improve fuel economy Refinement Cost and complexity reduction Competitive performance Priority: Best Bang for Buck Gains in propulsion efficiency are best built upon reduced vehicle energy demand, as it maximizes the impact of transmission matching and allows engine size and technology to be optimized. 18

19 Controls & Simulation Electrified System Optimization Electrical Losses EMA 1 Combustion Engine Losses P VM [KW] M VM [Nm] 4 2 n VM [1/min] P VEM1 [KW] M -2 EM1 [Nm ] P VEM1 [KW] -1 1 n EM1 [1 Electrical Losses EMB 2 M -2 EM1 [Nm ] -1 1 n EM1 [1 Battery Losses + = P VG [KW] n AB [1/min] 4 2 n VM [1/min] Transmission Pump Losses P L [KW] T IC E [Nm ] Overall Powertrain System Loss 5 M [Nm] N IC E [1 P VB [KW] M VM [Nm] 5 n VM [1/min] The optimal solution is found in the minimal point of the sum of all losses 19

20 Pragmatic Model Driver Customers Regulations Competition Suppliers Energy Cost Vehicle Energy Demand Transmission / Driveline Matching Electrification (HEV, ReEV, BEV) Engine Improvement Overall Objectives Improve fuel economy Refinement Cost and complexity reduction Competitive performance Priority: Best Bang for Buck Gains in propulsion efficiency are best built upon reduced vehicle energy demand, as it maximizes the impact of transmission matching and allows engine size and technology to be optimized. 2

21 Summary Automobile energy efficiency can be viewed as the relationship between Vehicle Demand Energy and Propulsion Efficiency over a given drive cycle Increasing energy efficiency should be a total vehicle exercise requiring detailed improvements in both Vehicle Demand Energy and Propulsion Efficiency Reductions in Vehicle Demand Energy typically provide better "Bang for the Buck" and are synergistic with electrification scenarios Electrified powertrains require closer cooperation between the traditional mechanical and electrical disciplines to maximize energy efficiency 21

22 Thank You 22