MBECS-III

Motor Vehicle Brake Energy Conservation System

New Aerostar Now on Sale Featuring MBECS-III First hybrid commuter bus with one-step system

Mitsubishi Motors Corp. earned widespread plaudits for its innovative MBECS-II, a revolutionary diesel/accumulator hybrid system that completely met long-term regulatory targets for slashing exhaust gas production in its vehicles. On October 19, 1996, Mitsubishi Motors launched an advanced version, the MBECS-III, in a bid to create a people-friendly bus for the 21st century. Incorporated in the new model of the New Aerostar, a large commuter bus, MBECS-III represents a quantum leap in environment-friendliness, safety, economy and comfort. Sales began at the end of 1996 in Japan.
MBECS: Motor vehicle Brake Energy Conservation System

System Summary

MBECS-III is formed centering on a brake energy conservation system and an oxidation catalyst and idling stop and start system. MBECS-III aims to drastically reduce nitrous oxide, particulates(substance of particles) and the emission of black smoke; and attain a further improvement in mileage.

Brake Energy Conservation System

In conventional vehicles, kinetic energy which had developed was transformed into frictional energy during braking and emitted into the air. This system materializes energy conservation and a reduction in emissions gas by efficiently accumulating energy emitted into the air and reusing such as an energy source when starting the vehicle.

Idling Stop & Start System

Until now, 5-10% of the fuel used by city busses on their routes was used while the engine was idling during stops.
MBECS-III enables a further conservation of energy by including a function which automatically stops the engine while the bus is stopped and thus restrains the wasteful consumption of fuel while stopped.

Oxidation catalyst

The regeneration of the brake energy results in the reduction of the engine load and thus use of an oxidation catalyst, which had been said to be impossible during high load, becomes possible. This results in a large reduction of particulates.

MBECS-III includes several conventional improvements

The capacity of the hydraulic pump/motor was increased and the pump/motor clutch was enhanced to deliver further reductions in fuel consumption, improved internal noise reduction and simpler maintenance. Mitsubishi Motors also improved the design of system components such as the differential and hydraulic fluid tank to enable a low one-step vehicle structure to be incorporated into the cabin floor.

Effects of MBECS-III

Reduced gas emission

Note: MBECS-III also meets or exceeds other long-term restriction target values for black smoke and other exhaust gas criteria not shown above.

Practical application

While actual fuel consumption varies considerably with driving conditions, in city driving the MBECS-III obtains an average 23% improvement in fuel consumption over conventional vehicles. The greatest improvement in energy conservation is seen in routes with frequent bus stops and no traffic congestion, when the MBECS-III achieves a striking 30% saving in fuel consumption.
Black smoke, the worst emissions of which occur at engine start and acceleration, is reduced as much as 50-70% by assisting engine drive with a hydraulic motor.

Overview of New Aerostar incorporating the MBECS-III

The New Aerostar is the world's first hybrid commuter bus to enable inclusion of low-floor one-step construction (550mm from ground to floor at front door).
Changes were added to the MP337 (leaf suspension) and MP737 (air suspension) models such as two-step and one-step configuration as well as wheel-base and door position specifications to specify 4 models in a total of 12 types for the New Aerostar (main components such as the engine, transmission, and electronically controlled kneeling system are the same as in existing vehicles).

New one-step setting (first in a hybrid bus)
The New Aerostar lineup includes a one-step type that makes boarding and disembarking easy for everyone from children to seniors.

Two-Steps Model

One-Step Model

Major Specifications (For Japan Models)

Model Code		KC-MP337K(F)	KC-MP337M(VF)	KC-MP737K(F)	KC-MP737M(VF)
Suspension		Leaf suspension		Air suspension
Step & Door type		Two-steps Front and middle doors	One-step Front and middle doors	Two-steps Front and middle doors	One-step Front and middle doors
Dimensions (mm)	Overall length	10,195	10,695	10,195	10,695
	Overall width	2,490
	Overall height	3,090	3,045	3,090	3,045
Gross vehicle weight (kg)		14,360	14,520	14,410	14,670
Passenger capacity		73 passengers + 1 crew	71 passengers + 1 crew	69 passengers + 1 crew	69 passengers + 1 crew
Engine	Model code	6D24 (L6, D1)
	Bore x stroke (mm)	130.0 x 150.0
	Total displacement (cc)	11,945
	Max. output (JIS)	240 ps (175kw)/ 2,200 rpm
	Max. torque (JIS)	85 kg-m (835 N-m)/ 1,400 rpm
Hydraulic pump / motor	Structure	Inclined plate type axial plunger model
	Capacity	125 cc / rev x 2 (twin)
	Operation pressure range	19.6-34.3MP2 (200-350 kg/cm2)
Accumulator	Model	Piston model
Accumulator	Capacity	46 litres x 2

NEXT TOPIC:"Preparation of the Vehicle Overhaul Manual"