Overview: a hydraulic stop & start system for larger engines used on urban vehicles. The heart of CleanStart(TM) is a hydraulic motor starter that is mounted directly on the crankshaft of the combustion engine. The engine can be turned off while boarding and unboarding passengers, in traffic jams as well as stopping at street lights, thus saving fuel and eliminating pollution. Using energy storage accumulators to power the motor, the engine starter is extremely responsive, thus quickly enabling the vehicles movement again.
Summary
o The Stop and Start: How is it relevant to "heavy" vehicles?
o Poclain Hydraulic's Technical Solution
o Hydraulic Starters in Comparison to Electric Starters
o Present Results
The Stop and Start: How is it relevant to "heavy" vehicles?
The Stop and Start, launched by Citroën in 2004 on a light urban vehicle, the C3, then re-worked by Mercedes on utility vehicles, enables engines to be stopped when the vehicle has been standing still for more than three seconds.(traffic lights, traffic jams, etc.). When the brake pedal is released, the engine instantly starts-up again (0.4 second response time).
The Potential Fuel Consumption
A study conducted in the USA by Southwestern Research Institute highlighted the various levels of action to reduce fuel consumption. They are proportionally different depending on the type of cycle (urban or Sabathé) required by the driving in a country. The road to consumption reduction:
In Japan Improvement in Combustion Recuperation of Braking Stopping the (urban cycle) Engine Efficiency (50%) Energy (25%) Engine (25%)
In the USA Improvement in Combustion Recuperation of Braking Stopping the (Sabathé's cycle) Engine Efficiency (45%) Energy (30%) Engine (10%)
In effect, light vehicle manufacturers announce (% of litre consumption /100km): (Sources: PSA and moteurnature.com) Citroën (Sabathé's cycle on the C3) 6 % Mercedes (Sabathé's cycle on the Sprinter) 5 - 8 %
With the strength of these results, the use of stop and start in heavy vehicles subject to frequent stopping is today relevant and even more so since the number of this type of vehicle manufactured each year is substantial: Urban Buses 25 000* Urban Garbage Trucks 10 000* Road Tractor 300 000*
* estimated for 2006 Hydraulic Starters in Comparison to Electric Starters
HES 02 Electric Starter
Performance / Consumption
Starts combustion engines, up to 16 liters Starts combustion engines, up to 16 liters
High speed cranking (600 RPM), enough to Low cranking speed (200 RPM), that directly crank the engine requires overfueling to enrich the fuel, causing a peak in consumption
Greater responsiveness due to its Low responsiveness as it acts on the positioning on the crankshaft (0.4 seconds), reduction ring (> 0.5s) with high without mechanical loss mechanical losses
Can perform a high number of start-ups in a Number of start-ups limited by smaller amount of time thanks to the battery power accumulator
Recharges very quickly as it requires a low Charging takes a long time due to high power charge supplied by the accumulator amount of power required
Compact and light weight: 17 kg ( 35lbs)
Safety
No electrical dangers Very high intensity required (500 amps) Fire-resistant as a high torque is needed, thus a high capacity battery. The electrical circuit dangers may cause fires.
Robust and sealed from exterior agents Not sealed
Enables start-up in absence of energy reserve Start-up not possible with a flat battery
Present Results
o Fuel Consumption Reduction: 5%
o Increased Safety
o Comfort: Noise and Vibration Reduction
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