Download presentation
Presentation is loading. Please wait.
Published byClinton King Modified over 5 years ago
1
The European Approach to HDV Fuel Economy - VECTO
HD Fuel Economy measurement workshop GRPE, 7 January 2019
2
Content Background Overview “VECTO method”
Simulation tool Component testing Validation Open issues VECTO application in Commission Regulation (EU) 2017/2400 as regards the determination of the CO2 emissions and fuel consumption of heavy-duty vehicles Main principles Vehicle Segmentation Generic data
3
Background
4
Background: Possible options for HDV CO2 certification
Engine test: CO2 emissions of the engine in [g/kWh] in a standard cycle (WHTC) + Test procedure already defined – No assessment on vehicle efficiency Road load test + chassis dynamometer test: + Fuel consumption of entire vehicle [g/km] o Needs separate testing of air drag and rolling resistance as input – Costly due to manifold combinations of engines, gearboxes, axle, tires.. – Vehicles might be optimised for chassis dyno testing For the HDV CO2 certification different methods have been discussed. Testing only the combustion engine would be rather simple because the test procedures are already defined. But a truck is not only the engine. To assess the efficiency of the whole vehicle several other components need to be considered. Road load tests and chassis dynamometer tests measure the fuel consumption of the entire vehicle. However, the main downsides are that it is costly, both in time and resources, due to manifold combinations of engines, gearboxes, axle, tires, etc. Testing a vehicle on the chassis dynamometer always requires some modifications in the vehicle’s internal control to trick the vehicle it is driving on a road. So this opens the door for optimizing the vehicle’s control units for chassis dyno tests.
5
Background: Possible options for HDV CO2 certification
On-road test: + Fuel consumption of entire vehicle [g/km] – Costly due to manifold combinations of engines, gearboxes, axle, tires.. – Poor reproducibility Component tests plus vehicle simulation: + Fuel consumption of the entire vehicle [g/km] + Cost efficient since measured component data can be applied in all vehicles + High reproducibility and flexibility – Regular updates of simulation tool necessary to cover relevant technologies On-road tests would also measure the fuel consumption of the entire vehicle. But similar as with chassis dyno tests the effort is quite high due to the many possible combinations. Optimizing controllers is hardly possible, but the reproducibility of results is very poor due to different environmental conditions and can (at least with current available methods) not meet the demands of a CO2 certification. The selected and implemented method is a combination of hardware component tests and a software simulation. This approach considers (potentially) the whole vehicle and appears to be the optimum of the trade off between effort and accuracy/reproducibility of the results. Measured component data can be used for simulating all vehicles where this component is installed – so every component (more precisely family of components) is only measured once. This allows to easily simulate thousands of different combinations of powertrain components. The downside of this approach is that it requires constant maintenance and updates to cover upcoming relevant technologies. Certain OEM-specific functionality, implemented in the vehicle’s control units, is currently not reflected in the simulation models.
6
Overview VECTO method
7
Overview “VECTO method”
Full load curve Fuel map Correction factors Loss maps igears, max. torque rdyn, RRC Cd x A, Mass,… Model Input Tires Vehicle Auxiliaries *generic data for trucks *specific for buses Pe = PAir + PRoll + PAcc PGrd + PLoss + PAux Air Compressor HVAC Alternator Cooling fan Steering pump HDH System motor, battery RESS Motor Component tests N [rpm] T [Nm] From a high-level perspective, the VECTO process works as follows: All relevant powertrain components are measured and the measurements are evaluated according to the technical descriptions. This component data is the basis for the simulations For a vehicle, the model data is created from (a) vehicle specific parameters such as curb mass or axle configuration etc. and (b) the component data of all installed powertrain components. So we get a quite large set of model parameters for a single vehicle. VECTO now computes the fuel consumption by calculating the equations for longitudinal dynamics, taking into account the losses of all relevant components.
8
VECTO simulation tool VECTO (“Vehicle Energy Consumption calculation TOol) is a simulation tool for energy demand, fuel consumption and CO2 emissions with the main features: longitudinal dynamics modelling “backward” calculation approach (predominantly) “Look ahead” functionalities approx. 0.5 s simulation time steps
9
Mission profiles and driver model
Mission profiles are target-speed cycles over distance Generic driver model Acceleration/deceleration behaviour Coasting Overspeed Gearshift strategy (MT, AMT, AT) … Individual vehicle specific realistic vehicle specific speed profiles Fully comparable results between different vehicles (no oscillations like in forward models) It is important to understand that the simulation results reflect a realistic, vehicle-specific speed profile. The mission profiles themselves are defined as target speed over distance. So every vehicle drives exactly the same distance, independent of the vehicle configuration – some may be slower, some are faster (in time). The driver model now yields a realistic speed profile by (a) limiting the acceleration/deceleration, (b) do coasting in certain situations, (c) allow certain overspeed, … The vehicle-specific speed profile is not a pre-processing step of the target-speed cycle but is a result of the simulation. It is important that the driver’s acceleration limits are reasonable. As a consequence, the simulation results of different vehicles give comparable results. Comparing driving a truck with a 500kW engine or a 250kW engine, for example, will typically not show twice the acceleration from standstill in a real-world situation, but the higher-powered truck can reach the target speed in a steep uphill situation whereas the lower-powered truck will drive at lower speeds. The picture shows part of Regional Delivery cycle, the red curve depicts the target speed while the blue curve is the vehicle’s actual speed in the simulation. The green curve shows the road gradient. Mission profiles for trucks: Long haul, regional delivery, urban delivery, municipal delivery, construction
10
Component testing Constant speed test with „standard body“ and/or trailer. Measure torque at wheels and air speed. Slope = r/2 x Cd A Drum test according to Regulation (EC) No 1222/2009 Specific tire label value e.g kg/ton The vehicle’s air drag resistance (combined Cd * A value) is obtained from a constant speed test. In this test the vehicle is equipped with a standard body and, depending on the vehicle group, a standard trailer. On a test track measurements at high and low vehicle speeds are conducted. Based on these measurements and advanced evaluation tools the CdxA value can be derived. Details about this will be given in a dedicated session on air drag measurements. The tire’s rolling resistance is measured on a drum test according to EC regulation 1222/2009. Output if the tire testing is the rolling resistance coefficient (RRC) for a given tire test load (FzISO)
11
Component testing Loss map options: 1) default values 2) measured idle losses + calc. torque dependency 3) Complete measurement Map for losses for each gear Engine test bed according to UN/ECE Regulation 49: WHTC, full load curve, motoring curve and steady state fuel map Fuel map, Full load, motoring curve WHTC correction factors For torque transferring components, i.e., gearbox, angledrive, axlegear, the loss maps are measured on a test stand. The EC regulation defines the torque and speed set points where the torque loss has to be measured. It is possible to reduce the testing effort and measure only the idle losses and calculate the torque dependent losses. The result is a loss-map for each gear. Combustion engines are measured on a test bed according to R49. Measurements contain the engine’s full-load curve, motoring curve and a steady state fuel map. Transient effects in the fuel map are considered in the so-called WHTC correction factors. These are obtained by comparing the simulated fuel consumption of the WHTC cycle with the measured fuel consumption on the WHTC cycle. For the retarder only the idling losses are measured.
12
Standard values for component data
Vehicle Component VECTO Input Component Test Generic “standard values” Engine Engine dyno Not applicable Air drag Constant speed test (test track) Available Rolling resistance Tire drum Transmission Test rig Test rig + generic Generic only Retarder Axle Angle drive Auxiliaries Lorries: not applicable Technology dependent Plus “Family concepts” to reduce number of component tests This table gives an overview on the availability of standard values for different components. For the engine it is mandatory to do a component test on an engine dyno. For all other components generic default values are available. Please note, that the generic values reflect CO2 related properties which are worse than a worst-case real component. So the decision whether to save efforts for component testing have to be considered carefully. For the gearbox it is possible to measure only the higher gears and use default values for the lower, not so fuel consumption relevant, gears. Hence, a combination of component testing and generic values is allowed. To reduce the number of required component tests, the component manufacturer may group similar components into a family. A single component test is then representative for the whole family. For component families the worst case principle applies. This means the worst component needs to be measured. The rules for grouping components into a family are defined for every component type.
13
General approach for auxiliaries (Lorries)
Considered auxiliary units: Engine cooling fan Steering pump Electric system Pneumatic system HVAC system Power take off (PTO) Technology dependent generic tables or functions for constant average power demand in VECTO simulations Auxiliary technology has to be defined in VECTO input data Auxiliary power demand depends on technology and driving cycle For trucks the following 5 (resp. 6, when considering PTO) auxiliary types are considered: Engine cooling fan, Steering pump Electric system (lights) Pneumatic system (air compressor) AC system Gearbox power take off (PTO) The PTO idling losses are modeled similar to auxiliaries with a constant power demand. For every auxiliary type a technology has to be selected from a predefined list. The average (constant) power demand used in the simulation depends on the selected technology and the driving cycle.
14
Example: Engine cooling fan
The table on this slide shows the average mechanical power demand for the engine cooling fan on different driving cycles. The power demand depends on the fan drive and fan control technology. For all other auxiliaries the power demand is defined in the same way.
15
Model validation (“Proof of concept”)
Measurements conducted by OEMs (component tests) and JRC (on-road full vehicle tests) Test route near JRC (Ispra, IT) Test Equipment: FC on-board measurement GPS and ECU data Torque-measurement rims On-board anemometer ... Comparison of measured and simulated fuel consumption in on-road full vehicle tests Mercedes-Benz Actros DAF CF75 40t (33.6t test weight), EURO VI, 330kW 18.6t (14.3t test weight), EURO V, 265kW Application Deviation Target speed cycle with VECTO driver model % Measured vehicle speed as input % Application Deviation Target speed cycle with VECTO driver model -0.5% Measured vehicle speed as input +1.8% During the course of the VECTO development the approach has been validated several times. The best documented validation excercise was the “proof of concept” performed in 2014 by DG JRC in cooperation with ACEA. Two different vehicles were equipped with measurement equipment for fuel consumption, torque measurement rims, GPS, etc. and the measured fuel consumption was compared with the simulated fuel consumption. The deviation between the simulated and measured results for a Mercedes-Benz Actros were in the range of +1.1% to -3 % and for a DAF truck between -0.5% and +1.8%.
16
VECTO: Main Open Issues and Future Challenges
Update generic gear shift strategies (AMT, AT) in progress Advanced Driver Assistance Systems (“ADAS”) Engine stop-start, Eco-roll, predictive cruise control in progress Advanced engine technologies e.g. dual fuel engines, waste heat recovery in progress Methods for buses and coaches in progress Vehicles not exceeding 7.5 tons under preparation Hybrid electric vehicles (He-HDV) in progress Incorporation of specific designs of bodies, trailers and semitrailers into the CO2 certification in progress Incorporation of OEM specific control strategies long term challenge
17
Application of VECTO according to Commission Regulation (EU) 2017/2400
18
The “VECTO process” Main principles:
Every vehicle gets an individual VECTO result All data shall be handled in electronic form Data integrity measures installed “hashing” The EC regulation requires that every vehicle gets its individual VECTO result. The vehicle identification number (VIN) is part of the vehicle description and part of the VECTO result reports. VECTO is among the first, if not the first, legislation that is based on simulated data. Consequently, all VECTO related data shall be handled in electronic form. Measurement data is evaluated according to regulation EU 2017/2400 in component evaluation tools and the result is the component’s model data in XML format. For air drag and engine evaluation TUG provides a component evaluation tool. For all other components, unfortunately, no common evaluation tool exists. The VECTO results are two XML reports, one as customer information (CIF) and another for certification and monitoring (MRF). The high-level VECTO process is visualized on this slide. Output of the component measurements is a set of files with the measurement data. This measurement data is evaluated according to the EC regulation 2017/2400 and the component data is put into a defined XML structure. The component data is stored of course by the component manufacturer but also the vehicle manufacturer requires the component data for vehicle certification. When the vehicle is produced, the vehicle manufacturer creates the vehicle description (job data) from its database and simulates the vehicle in VECTO. VECTO generates two XML reports, the Customer’s Information File (CIF) and the Manufacturer’s Record File. The former is used for customer information and the Certificate of Conformity while the latter is for certification and monitoring. Note: the XML reports have a stylesheet information included (hosted on CITnet server) so the XML files are nicely rendered in a modern web browser.
19
Vehicle segmentation (lorries)
All generic model data is defined based on the “vehicle group” Driving cycles (“mission profiles”) Standard body and/or trailer Payload and load distribution Auxiliary power demand Vehicle group is defined by Axle configuration (e.g. 4x2) Chassis configuration (rigid, tractor) Technically permissible maximum laden mass (TPMLM) Before discussing the generic data we need to introduce the vehicle “segmentation” (i.e. the allocation of a particular vehicle to a certain “group”). Trucks are assigned to a vehicle group depending on three vehicle parameters, namely the axle configuration (e.g, 4x2, 6x2, 6x4), the chassis type (rigid or tractor), and the maximum technical gross vehicle mass. In total 18 groups are defined and 10 out of this are subject to CO2 declaration (groups 4, 5, 9 & 10 as from ; groups 1, 2 & 3 as from , groups 11, 12, 16 as from ). The vehicle segmentation is used to assign generic model data such as the Standard body and/or trailer Payloads and load distribution Auxiliary power demand Driving cycles
20
Lorry Segmentation (Table 1 of Annex I to Commission Regulation (EU) 2017/2400)
* EMS - European Modular System ** in these vehicle classes tractors are treated as rigids but with specific curb weight of tractor T…Tractor R… Rigid & standard body T1,T2… Standard trailers ST…Standard semitrailer D… Standard dolly This screenshot of the segmentation table from HDV CO2 Annex I, Table 1 shows the allocation of mission profiles and the simulated vehicle configuration for every mission profile. A group 9 vehicle, for example, is a 6x2 rigid truck, independent of the technical max laden mass. Such vehicles are simulated on the long haul, regional delivery, and the Municipal utility missions. The default body for a group 9 rigid truck is a B5 body. The long haul cycle is simulated with a T2 standard trailer while the regional delivery and municipal utility cycles are simulated without a trailer. If the vehicle’s engine power is above a certain threshold (300 kW), the long haul and regional delivery cycle are in addition simulated in the EMS configuration. In the EMS configuration a dolly plus a standard semitrailer are considered. This means for a group 9 vehicle 10 simulation runs (5 cycles with two different payloads) are required.
21
VECTO mission profiles: Long haul
Trip length: 100 km Average speed: approx. 80km/h Stop time: 67 s This slide depicts the mission profile (target speed, road gradient, stop time) for the long haul cycle. The long haul cycle is characterized by driving at a constant speed for a long distance. It has only two stops.
22
VECTO mission profiles: Regional delivery
Trip length: 100 km Average speed: approx. 60km/h Stop time: 746 s This slide depicts the mission profile (target speed, road gradient, stop time) for the regional delivery cycle. The regional delivery cycle contains 3 phases. First an urban part, driving at low speeds with many speed changes and several stops, second a rural part driving at about 70km/h target speed with a few stops, and third a highway part, driving at 80 to 85 km/h.
23
VECTO mission profiles: Municipal utility
Shall reflect typical operation of a refuse truck of type “rear loader”. The cycle consists of three parts: 1. Approach to the area of garbage collection 2. Collection part 3. Drive from the area of garbage collection to the waste processing side Vehicle is simulated with a generic refuse body incl. PTO Collection part: Trip length: 2.9 km Average speed: approx. 3 km/h Total cycle: Trip length: 11.2 km Average speed: approx. 9 km/h This slide depicts the mission profile (target speed, road gradient, stop time) for the municipal utility cycle. The municipal utility cycle consists of 3 parts: first approaching to the area of garbage collection, second the garbage collection part and third driving to the waste processing site. This cycle is considerably shorter as the others due to the collecting part. During garbage collection a load pattern typical for a rear loading refuse body is applied to the engine. The other cycles (regional delivery, urban delivery) are currently being updated
24
Thank you for your attention. For more info: JRC-VECTO@ec.europa.eu
25
Verification Testing Procedure (VTP)
On-road test to verify the CO2 emissions of new vehicles after production To be carried out by the vehicle manufacturer, verified by the approval authority Main measurement signals: Torque and speed at the driven wheels Engine speed Fuel consumption Signals for 1. and 2. are provided as “cycle” input to VECTO „VTP mode“ together with the vehicle related input data from the CO2 certification Pass/Fail check: Wheel work specific fuel consumption (g/kWh) from VTP measurement has to be lower than VECTO simulation result plus tolerance (7.5%) Additionally correctness of vehicle input data shall be checked (hashes, components, technology selection for auxiliaries etc.)
26
Verification Testing Procedure (VTP)
27
VECTO VTP Mode Vehicle verification implemented as separate simulation mode Input: measured cycle Output: comparison of (corrected) measured cycle with declared CO2 value Separate XML report
Similar presentations
© 2025 SlidePlayer.com. Inc.
All rights reserved.