Automotive Systems course (Module 05) - Preheating Systems for vehicles with Internal Combustion Engines

18 de novembro de 2016 | 1
SistemasAutomóveis
ICE (pre)Heating Systems
Mário Alves (mjf@isep.ipp.pt)

SistemasAutomóveis
Outline
• Classification of (pre)heating systems
• Combustion chamber preheating
• Intake air heating
• Fuel & exhaust system heating
• Glossary
• Recommended references

SistemasAutomóveis
Classification of (pre)heating systems
• Combustion chamber preheating
• Intake air heating
• Fuel & exhaust system heating

SistemasAutomóveis
Combustion chamber preheating
• In CI engines, air/fuel mix ignition results from compression
and temperature
• for cold engine (specially in cold weather), the inertial mass of
engine cylinders/block absorb the heat of compression, preventing
ignition
• glow-plugs are used to aid the engine
• cranking (helps vaporizing the fuel)
• warming up (reduces smoke and engine knocking)
• Glow-plugs
• long-shaped electric heaters
• reach ≈1000 ºC in a couple of seconds
• glow-plug tip pointed to
• pre-chamber  indirect injection
• combustion chamber  direct injection
http://www.eurotechmotors.com/lit-up-like-a-christmas-tree/

SistemasAutomóveis
https://www.ngk.de/en/technology-in-detail/glow-plugs/glow-plugs-basic-principles/

SistemasAutomóveis
https://www.quora.com/What-is-the-difference-between-direct-and-
indirect-fuel-injection
Glow-plug location in direct injection
Glow-plug location in indirect injection

SistemasAutomóveis
• Glow-plug
• pencil-shaped device with heating element at tip
• Construction
• metal sheathing – metallic heating coil
• ceramic sheathing
http://www.ngkntk.co.uk/index.php/technical-centre/glow-plugs/

SistemasAutomóveis
• Metal sheathed glow-plug
• glow tube filled with magnesium oxide powder:.
(electrical insulator, heat conductor and
vibration/impact absorber)
http://www.ngk.com.au/glow-plugs/technical-information/glow-plug-types
https://www.ngk.de/en/technology-in-detail/glow-plugs/design-of-a-glow-plug/design-of-a-metal-glow-plug/

SistemasAutomóveis
• Ceramic (silicon nitrite) sheathed glow plug
• compact design, good thermal conductivity
• higher glow temperatures and faster heating
https://www.ngk.de/en/technology-in-detail/glow-plugs/design-of-a-glow-plug/design-of-a-ceramic-glow-plug/

SistemasAutomóveis
• States of a glow-plug
• <80s  several tens of seconds to reach max temperature
• >80s  few seconds to reach max temperature
https://www.ngk.de/en/technology-in-detail/glow-plugs/glow-plugs-basic-principles/

SistemasAutomóveis
• Self-regulating glow-plugs
• auto-protection against overheating, by
limiting the current from the battery
• why? to prevent glow-plugs from burning out
• due to the heating of the glow-plug itself
• due to sudden rise in charging system
voltage (when alternator starts
generating)
• due to the heating of the engine warming-
up
• regulator coil
• resistance grows with temperature
• inserted in series with the heating coil
http://www.google.gg/patents/US5132516

SistemasAutomóveis
• Self-regulating glow-plug (example by Bosch)
http://www.ebay.com/itm/4-x-BOSCH-Duraterm-Glow-Plug-SET-TOYOTA-
1AZ-FSE-2RZ-FE-2KD-FTV-KZ-Diesel-Engines-/171077062129

SistemasAutomóveis
• Self-regulating glow-plug (example by NGK)
https://www.ngkntk.in/ngk-glow-plugs/

SistemasAutomóveis
• Self-regulating glow-plug (example by Brisk)
http://www.brisk.biz/catalogues/glow-plugs/tube-glow-plugs-for-diesel-engines

SistemasAutomóveis
• Glow-plug control
• “old” systems used dedicated hardware
• current systems are controlled by the engine ECU
• may feature a separated glow-plug controller/power unit
• Preheating phases
• pre-glowing
• starts at ignition ON (until engine cranking)
• glow plugs at full power
• cranking (starting)
• starts at ignition STA (until cranking ends)
• glow-plugs at full power
• after-glowing
• starts when cranking ends (engine running autonomously)
• for improved combustion, reduced exhaust gas emissions and smoother
engine operation
• duration may depend on coolant temperature

SistemasAutomóveis
• Glow-plug control (typical timing/state diagram)

SistemasAutomóveis
• Inputs (sensors)
• ignition switch position (OFF, ON, STA)
• coolant (or oil) temperature (for controlling glow timing)
• alternator charging signal (for signaling engine running)
• (glow plug current sensor (via low resistor voltage))
• (intake air pressure)
• (glow-plug voltage)
• Outputs (actuators)
• relay(s) (or electronic switches)  glow plugs (1 per cylinder)
• main relay (pre-glow)
• secondary relay (after-glow)
• glow plugs indicator light (instrument panel)
• (intake air preheater – for heavy-duty engines)

SistemasAutomóveis
• relay(s)  glow plugs (1 per cylinder)
• main relay (pre-glow)  full power/voltage
• secondary relay (after-glow)  reduced power (voltage
divider)
http://www.tb-training.co.uk/MarineE07.html

SistemasAutomóveis
http://www.moranbahweather.com/toyota/hilux/repair2/html/frame_rm000000wrb001x.html
• Glow-plug control (example 1)
http://www.moranbahweather.com/toyota/hilux/repair2/html/frame_rm000000w0b003x.html

SistemasAutomóveis
http://forum.ih8mud.com/threads/12v-super-glow-experts.537246/

SistemasAutomóveis
http://www.ford-trucks.com/forums/1034500-cold-start-issue.html

SistemasAutomóveis
(example 4)
http://www.moranbahweather.com/toyota/hilux/repair2/html/frame_rm000000wrb001x.html

SistemasAutomóveis
Intake air heating
• Heating intake air (specially in cold weather conditions)
• improves engine cranking
• smoothens cold-start engine operation (warm-up phase)
• helps reducing exhaust gas emissions (specially HC)
• Available technologies
• filament glow plugs
• simple to apply, proven design, long service intervals
• heating flange
• fast heating up, long life, very effective lowering emissions
• flame (combustion) start systems
• high heating, low electrical energy consumption, mitigates
white smoke
http://www.phillipsandtemro.com/heating_technology/air_intake_heaters.asp

SistemasAutomóveis
Intake air heating
• Flame Start Systems (based on a “flame” glow plug)
• once the heating temperature has been reached, fuel enters the
evaporator in the flame glow plug via a solenoid valve
• then, a flame is produced that heats the intake air
• Example (by BERU)
1. Electrical connection
2. Insulation
3. Plug housing
4. Fuel connection
5. Fuel feed
6. Metering device
7. Evaporator sieve
8. Evaporator pipe
9. Electrically heated
heater rod
10. Protective tube
11. Flame sleeve
http://beru.federalmogul.com/diesel-cold-start-technology/product-
description/diesel-cold-start-technology

SistemasAutomóveis
Intake air heating
• Heating flange systems
• electrical heating output is transmitted to the ambient or through-
flowing air via a heating coil
• heating coil consists of highly corrosion-resistant flat wires
• special form of the heating coil add to its vibration resistance,
guaranteeing play-free expansion during temperature increase
• Example (by DBK)
• voltage range: 12V / 24V
• power range: up to 7 kW
• Heating time: 3 s
http://www.dbk-group.com/us/195/dbk-solutions/automotive-%2B-power-applications/intake-air-preheating.html

SistemasAutomóveis
Intake air heating
• Filament glow plug
• for older heavy-duty diesel vehicles (tractors, tow trucks and
construction machines), as well as stationary engines
• wire filament is the heating element
https://www.rpmoutlet.com/diaafe222a.htm
http://www.brisk.biz/catalogues/glow-plugs/intake-air-heaters

SistemasAutomóveis
Intake air heating
• Example (2000 Ford F250/350 series)
http://www.justanswer.com/ford/4epb5-ford-f350-superduty-pickup-4x4-
2000-ford-f350-7-3-diesel.html

SistemasAutomóveis
Fuel & exhaust system heating
• Heating Diesel fuel may be needed because
• at low temperatures, diesel fuel forms paraffin crystals
(suspended in the liquid)
• as the concentration increases, the fuel filter may become blocked
• the engine could stall (diesel waxing)
• so fuel is preheated in the fuel line, where it melts the paraffin
crystals before they reach the primary filter
• Types
• in-line fuel heaters
• found in most Diesel vehicles, usually located upstream
(attached to) the main filter
• in-tank fuel heaters
• only in heavy-duty vehicles and extreme weather conditions

SistemasAutomóveis
• In-line fuel heaters
• Electrical heater
• in the fuel filter
• inside fuel line
http://www.arctic-fox.com/products/arctic-fox174-in-tank-fuel-warmers
http://www.autozone.com/repairguides/Ford-Tempo-Topaz-1984-1994-Repair-Guide/ROUTINE-MAINTENANCE/Fuel-Filter/_/P-0900c1528005d3e0

SistemasAutomóveis
• In-tank fuel heaters
• maintains fuel temperature levels recommended by engine
manufacturers for electronic fuel systems
• uses coolant fluid heat to warm-up the fuel
• optional integrated mechanical thermostat to by-pass fuel
warming loop when fuel temperature reaches optimum

SistemasAutomóveis
• Diesel Exhaust Fluid (DEF, aka as AdBlue)
• solution composed of urea (32,5%) and deionized water (67.5%)
• used in Selective Catalytic Reduction (SCR) systems to reduce
NOx concentration in Diesel exhaust emissions
• this solution (adBlue; a consumable) must be heated and injected
into the exhaust system
• DEF is a consumable (2% of fuel consumption), thus vehicles
using these catalytic converters have a specific tank for DEF
• DEF tank/injector heaters
• DEF cannot freeze (< 11º C; ideal = -5º to 30º C)
• heating for the DEF tank and supply lines must be provided
• DEF heating can be electrical and/or engine coolant-based

SistemasAutomóveis
• DEF heating (Example 1 – Isuzu)
http://collision.enterprise.alldata.com/online2help/techRef/Diesel_Car_and_Truck_Visual_In
spections/Isuzu.htm

SistemasAutomóveis
• DEF heating (Example 2 – Bosch)
http://www.technology.matthey.com/article/59/3/221-232/

SistemasAutomóveis
• DEF heating (Example 3 – Delphi)
http://www.delphi.com/manufacturers/auto/powertrain/diesel/em-tech/scrds

SistemasAutomóveis
• SCR heating
• SCR needs exhaust gas temperature > 200°C to ensure a complete
decomposition and hydrolysis of urea to ammonia
• typically depends on engine/exhaust gas temperatures to reach its
operating temperature
• electrically heated catalyst minimizes cold start emissions by
reducing SCR heating time: Emicat
http://www.emitec.com/en/technology/catalyst-substrates/emicat/

SistemasAutomóveis
• Emicat
http://www.car-engineer.com/emitecs-e-scr-system-for-nox-reduction/

SistemasAutomóveis
• Oxygen sensors
• oxygen (aka O2 or lambda) sensors monitor the amount of
unburned oxygen is in the exhaust system
• informs ECU about (burned) A/F mixture oxygen content – rich
(less oxygen) or lean (more oxygen)
• currently two O2 sensors per exhaust manifold (upstream &
downstream the catalyst)  for testing catalyst malfunctioning
• O2 sensors preheating
• O2 sensors only operate above  600º C
• cold-start  A/F mixture is computed without
feedback from O2 sensors (open-loop)
• electrical heating helps reaching
operating temperature more quickly
http://www.autocodes.com/articles/oxygen_sensor_location.php
https://www.volvoclub.org.uk/faq/EngineSensors.html

SistemasAutomóveis
• O2 sensors components/wiring
• unheated: 1-2 wires (obsolete)
• heated: 3-4 wires
http://www.autozone.com/repairguides/Acura-Coupes-and-Sedans-1994-2000-Repair-Information/Electronic-Engine-Controls/Oxygen-Sensor/_/P-0900c1528008be6b
http://www.lambdapower.co.uk/TechNotes/Tech-6.asp

SistemasAutomóveis
Glossary (English/Portuguese)
• …

SistemasAutomóveis
Recommended references
• https://aa-boschap-
uk.resource.bosch.com/media/parts/engine_systems__auto_parts_1/diesel__engine_syst
ems_1/glow_plugs/pia_glow_plugs_en_58333.pdf
• https://suw.biblos.pk.edu.pl/resources/i9/i9/i4/r994/IdziorM_ProblemsStarting.pdf
• http://www.beru.com/download/produkte/TI01_en.pdf
• http://emissions.borgwarner.com/download/produkte/whitepaper_iss_en.pdf
• M. N. Azpiazu, C. Bustamante, J. M. Morquillasz, “Effect of air preheating on
automotive emissions”, Springer journal of Water, Air, and Soil Pollution, Volume 51,
Issue 3, June 1990, pp 231-237. DOI: 10.1007/BF00158221
• http://www.lambdapower.co.uk/
• …

Automotive Systems course (Module 05) - Preheating Systems for vehicles with Internal Combustion Engines

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