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Automotive

Mitsubishi Electric puts the hybrid system on the crankshaft

By Aaron Turpen
October 26, 2017
Mitsubishi Electric puts the hybrid system on the crankshaft
Most commonly, 48V hybrid systems are used in engine stop-start designs with the motor acting as both the starter and brake regeneration system
Most commonly, 48V hybrid systems are used in engine stop-start designs with the motor acting as both the starter and brake regeneration system
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Most commonly, 48V hybrid systems are used in engine stop-start designs with the motor acting as both the starter and brake regeneration system
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Most commonly, 48V hybrid systems are used in engine stop-start designs with the motor acting as both the starter and brake regeneration system

Mitsubishi Electric has begun mass-producing the first crankshaft-mounted integrated starter-generator system for 48V hybrid systems. This system will be used by Mercedes-Benz and is on display at Tokyo Motor Show 2017.

Most hybrid systems are belt-driven, with the motor transferring power to the engine or drive shaft through belts and pulleys. These can limit maximum torque output allowances and can bleed some of the energy off. The Mitsubishi Electric integrated starter-generator (ISG) system connects directly to the crankshaft and eliminates those issues.

Most commonly, 48V hybrid systems are used in engine stop-start designs with the motor acting as both the starter and brake regeneration system. These systems are relatively low-cost to implement and give high returns for fuel economy. Mitsubishi Electric's system is designed to fit on the engine's crankshaft between the engine and the transmission.

Today's hybrid systems are aiding fuel efficiency and demand for them is expected to rise, especially in Europe. Mitsubishi Electric is mass-producing this new ISG for use in upcoming Mercedes-Benz models which use a 48-volt hybrid system. The company is working towards smaller and lighter weight versions of these higher-power ISGs as well.

Going with these goals, Mitsubishi Electric has its own proprietary coil winding technology for high-density configurations in 48V motors. These motors are designed to be thin in profile for flexibility in vehicle layout. Mitsubishi Electric also developed a new transfer-molded power module (inverter) for these systems to reduce heat resistance for added durability.

Source: Mitsubishi Electric

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AutomotiveHybridMitsubishiMotorTokyo Motor Show 2017
10 comments
Aaron Turpen
Aaron Turpen
Aaron is a Wyoming-based automotive journalist with interests in electronic and engineering technology. Outside of New Atlas, Aaron is a prolific writer, father of two, and would-be chicken farmer.

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10 comments
BanisterJH
If the proprietary coil winding technology makes their system efficient enough for hybrids, they might be able to make some very nice little auto starting generator sets also.
highlandboy
Placing the electric motor on the crankshaft has 3 immediately apparent disadvantages. Firstly motors are usually heavier than the flywheel they replace, making the motor less responsive. Secondly, the hybrid can not be run in electric only mode (without turning the Internal Combustion Engine). Thirdly (and related to the second point) regenerative braking is less efficient as some energy is lost turning the ICE (engine braking) when this is unnecessary. That being said, the simplicity of the design should make for lower initial costs, maintenance costs and longer mean times between failures.
steph_tsf
Great ! Mitsubishi and Mercedes innovate in 2017, copying the Honda IMA (Integrated Motor Assist) dating back from 1999 (Honda Insight) followed by the Honda Civic in the USA, from 2001 to 2015. Since 2012, the DC brushless permanent magnet motor of the Honda Civic Hybrid provides 23 hp. Since 2013, the successor of the Honda IMA is the Honda i-MMD (intelligent Multi Mode Drive), kind of serial-hybrid featuring a clutch enabling the thermal engine to direct-drive the differential ring gear above 45 mph or so. This allows cruising on interstate without wasting power in electronics (Toyota HSD issue), and without wasting power in a automatic gearbox (German and Korean hybrid cars issue). The Honda Accord Hybrid (i-MMD) remains alert on interstate because upon flooring the accelerator while running at say 70 mph, the 181 hp electric motor instantly adds its 225 Nm torque, to the 175 Nm torque of the 143 hp petrol engine. This is thus 400 Nm, pushing the Honda through the equivalent of say a 5th gear. Grab a $33,000 Honda Accord Hybrid and test it against a $55,000 Mercedes Class E. The Mercedes will be even more alert on interstate because its 400 Nm torque gets exploited by a 8-speed automatic transmission, capable of quickly downshifting to the 4th gear, possibly the 3rd gear in sport mode. And the Mercedes engine will produce less noise while running at 120 mph, once in 8th gear. Ask yourself if you want such performance. Watch out the next Honda Civic Hybrid, possibly i-MMD, possibly basing on the 3-cyl 1.5 liter turbocharged petrol engine (129 hp and 200 Nm). Get an eye to the Chrysler Pacifica Hybrid. And to the Mitsubishi Outlander Hybrid also. There are intriguing similarities. Possibly the Honda i-MMD, Chrysler Pacifica Hybrid and Mitsubishi Outlander Hybrid all derive from the GKN Multi-Mode eTransmission, available from 2013.
JimFox
highlandboy 'the hybrid can not be run in electric only mode (without turning the Internal Combustion Engine)'.
Then how can it be a hybrid? I don't understand your comment; is there a sort of clutch that can disengage the ICE? Very baffling.
JimFox
http://www.mitsubishielectric.com/news/2017/pdf/1026-b.pdf
I still don't get it- so the ICE must run 100% of the time & the motor cannot power the vehicle in pure electric mode? The diagram & text in the .pdf explain nothing, to me.
Mzungu_Mkubwa
@highlandboy, I think you're misunderstanding the article's use of the word "hybrid" (and perhaps its being misused?) This is not intended to be a driving motor (propelling the car forward) but simply an electrical assist to the engine in terms of start-stop functionality and powering supplemental 48v systems. A very informative article on the topic is found here: jalopnik.com/everything-you-need-to-know-about-the-upcoming-48-volt-1790364465
piperTom
The second and third of highlandboy's objections can be overcome simply by inserting a clutch between the engine and the motor/generator. The engine would turn only when additional power is needed. As to the first objection, it is overcome by using the battery to boost power when demand is high -- it's a feature, not a flaw.
Nik
Could this be used instead of a separate starter motor?
Gregg Eshelman
All these designs putting a motor/alternator etc on the output end of the crankshaft owe inspiration to the Owen Magnetic. https://en.wikipedia.org/wiki/Owen_Magnetic
dylan
The first starter generator system attached directly to the crankshaft was used by several small cars in the 60's and 70's and was known as a 'Dynastart'. The rotor was attached to the crankshaft and the coil to the crankcase. There were two sets of brushes. When rotated the unit produced 12v DC to charge the battery through a regulator When starting the engine a relay connected the other brushes directly to the battery thus rotating the engine. There really is nothing new!