The growth of xEVs and improvements to ICE vehicles (Part 1)

Further innovations to achieve thermal efficiency of over 45%

2017/07/12

Summary

  Various forums were held at the Automotive Engineering Exposition 2017 YOKOHAMA, which was organized by the Society of Automotive Engineers of Japan, Inc. and marked its 70th anniversary. Among these, a discussion was held regarding the status of innovations of gasoline engines under the theme of "The World of Powertrains in Passenger Vehicles in 2030." It was two years since the forum was last held, and guests from the industry, government, and academia discussed progress in the development of internal combustion engines.

  Representatives from Toyota Motor Corporation, Honda R&D Co., Nissan Motor, Mazda, Robert Bosch, AVL List, Waseda University, and the Japan Science and Technology Agency held lectures, and a panel discussion followed. A net thermal efficiency of 45% will be achieved soon, and the panel discussion featured the theme of "What technology will come next?"

  Toyota has implemented gasoline engines with a thermal efficiency of 41% or more in HEVs such as the Prius, C-HR, and Camry; and is currently expanding its lineup of new powertrains based on its TNGA concept globally. Honda has achieved a net thermal efficiency of 45.2% or greater for individual chambers in its i-CVCC sub-chamber rapid combustion system. By using VC-Turbo, Nissan Motor claims it can achieve both a high compression ratio of 18.0 and long-stroke operation by adopting the VC-Turbo engine. Mazda presented its research on reducing cooling loss with the use of heat shields that will be a 3rd step for its SKYACTIV system. Waseda University has been tasked by the Ministry of Land, Infrastructure, Transport and Tourism with achieving a target corporate average fuel efficiency in the JC08 mode of 20.3 km/L by 2020, but reports that net thermal efficiency of 50.35% can be achieved in gasoline internal combustion engines.

The "Powertrain for
Passenger Vehicle after 2030" panelists The aluminum-jointed space
frame in the NSX
The "Powertrain for Passenger Vehicle after 2030" panelists The aluminum-jointed space frame in the NSX. It achieves a natural frequency of 66 Hz
(Photographed by MarkLines at the Automotive Engineering Exposition)


Related Reports:
Research on revolutionary combustion technology(2): Contemplating the limits of innovation (Jan. 2017)
Research on revolutionary combustion technology: Contemplating the limits of innovation (Nov. 2016)
Automotive technology on the road to 2050 (Oct. 2016)
Evolution of the internal combustion engine (Feb. 2016)
JSAE Exposition 2015: Envisioning future of powertrains for passenger cars (1) (trends in Japan) (Jun. 2015)
JSAE Exposition 2015: Envisioning future of powertrains for passenger cars (2) (trends in Europe) (Jul. 2015)



The direction of powertrain development at the dawn of the age of electrification: (Mr. Tomoda, Toyota Motor Corporation)

  Toyota has implemented gasoline engines with a thermal efficiency of 41% or more in HEVs such as the Prius, C-HR, and Camry. It is currently expanding its lineup of new powertrains based on its TNGA concept globally. Toyota will work to improve engine thermal and powertrain efficiency in HEVs until 2030 on a well-to-wheel basis. Mr. Tomoda stated that the reason for this is that it is possible to bring the CO2 levels emitted by HEVs closer to the amount from electricity generation in developed countries such as Japan, the US, and Europe. The OEM will achieve this by increasing engine thermal efficiency to 50% (developing SIP innovative combustion technology), and using fuels such as biofuel that generate zero CO2 during their manufacture.

  • The image on the left in the figure below shows how the well-to-wheel rating of PHEVs and EVs is affected by CO2 production in the power composition of power plants (thermal power, hydroelectric power, nuclear power, etc.). In developed countries, PHEVs and EVs generate less CO2, whereas in developing countries, it is HEVs (with a fuel consumption of 40km/L) that emit less.
  • The image on the right in the figure below shows that in the short-to-mid-term (until around 2030), by 1) improving powertrain efficiency and 2) improving HEVs, achieving similar CO2 performance to EVs in developed countries would be possible. Additionally, by using biofuel in the long-term, HEVs can achieve even better CO2 performance.
Created by MarkLines based
on Toyota documents Created by MarkLines based
on Toyota documents
(Created by MarkLines based on Toyota documents) (Created by MarkLines based on Toyota documents)


Honda's engine technology for the electric vehicle age: (Mr. Niizato, Honda R&D Co., Ltd.)

  In an effort to reduce CO2, Honda will accelerate the release of EVs and is currently developing vehicles with a goal to have them compose 2/3 of its total sales in 2030. However, 85% of EVs will feature engines. In other words, the number of engines for HEVs will increase. The operating points of EV engines are broader than expected in actual driving modes.

    With HV-use engines:
  1. Coolant temperature rises slowly. (High efficiency combustion mode transition point: 205 seconds)
  2. There are multiple restarts. (Emissions countermeasures during low water temperature restarts are still a challenge)
  3. Vibration (NV) demands disable the use of the most efficient point in the low load range, leading to a loss in fuel efficiency.

  Given the above factors, EV engines need special support.

i-CVCC engine research

  Honda is currently fully engaged in the research of its i-CVCC engine. The i-CVCC engine is a modern update of the CVCC engine that was first developed by the OEM in the 1970s, with fuel ignited in a sub-combustion chamber and put into the primary combustion chamber at high velocity. By using this method, Honda is able to achieve 40% faster combustion than conventional lean-burn methods.

  In the air-fuel ratio, A/F is burned until 35, and the engine is reported to have achieved a net maximum thermal efficiency of 47% (!!!).

Created by MarkLines based
on Honda documents Created by MarkLines based
on Honda documents
(Created by MarkLines based on Honda documents) (Created by MarkLines based on Honda documents)


The first step towards the next evolution in internal combustion engines: (Mr. Hiraku, Nissan Motor)

  In 2018, Nissan will mass-produce the world's first production-ready variable compression ratio engine and equip it in its Infiniti brand vehicles, for North America. The VC-Turbo Engine can change its compression ratio continuously from 8.5 to 14 on demand thanks to the link structure of its cranks. (Previous report "Research on revolutionary combustion technology: Contemplating the limits of innovation")

  On paper, the engine will have a thermal efficiency just short of 40%. Additionally, the engine has the benefit of being made into a long-stroke configuration to increase fuel efficiency without increasing engine height.

  Furthermore, with the e-POWER unit featured in the Nissan Note, thermal efficiency is improved by about 5% due to the operating conditions of the internal combustion engine (intensive use of the most fuel-efficient point, major use of steady-state operation).

  In the future, the VC-Turbo Engine and e-Power engine will be important units for improving thermal efficiency.

Nissan Motor VC-Turbo Engine
(Source: Infiniti press releases)
Nissan Motor VC-Turbo
Engine
Nissan Motor ePOWER
Nissan ePower BMW i3
Engine 1.2-liter 3-cylinder gasoline engine (HR12DE)
Manufactured by Aichi Machine Industry Co., Ltd.
0.65-liter 2-cylinder gasoline engine (W20K06A)
BMW scooter engine
Compression ratio 12.0   Miller cycle output 58kW Compression ratio 10.6   Output 28kW
Motor rated output 70kW 75kW
Battery Lithium-ion 1.47 kWh Lithium-ion 33 kWh
Fuel tank 41 liters (unleaded regular gasoline) 9 liters (unleaded premium gasoline)
Hybrid system HEV PHEV
Fuel efficiency 37.2 km/L (S type) JC08 mode 24.7 km/L JC08 mode
Gross vehicle weight 1445-1505kg, seating capacity for 5 1640 kg, seating capacity for 4
Price range JPY 2-3 million JPY 5 million or more
Created by MarkLines based
on Nissan and BMW press releases
(Created by MarkLines based on Nissan and BMW press releases)


The continued efforts of the internal combustion engine: (Mr. Yamamoto, Mazda)

SKYACTIV 3rd step

  The only OEM at the forum to not speak about xEVs was Mazda. As Mr. Tomoda from Toyota explained, the most effective way to reduce the well-to-wheel rating is to eliminate thermal power generation such as the use of coal. Additionally, the CO2 emissions from the SKYACTIV 3rd step engines comes extremely close to EV well-to-wheel levels.

  Mazda's policy will be to stick to internal combustion engines.

SKYACTIV
3rd step SKYACTIV 3rd step

  The SKYACTIV 3rd step engine reduces cooling loss to the utmost, and has cuts cooling loss 70% in comparison to the 1st step (above right image). As a result, the thermal efficiency shows a gross improvement from roughly 40% to 56% (red section in the top right image).

SKYACTIV 3rd step
(Created by MarkLines based on Mazda documents)

  The break specific fuel consumption (BSFC) at 1500 rpm shows an improvement from 53% in the G1 (1st step 2.0-liter gasoline SKYACTIV) to 34% in the G3 (3rd step 2.0-liter gasoline SKYACTIV) engine load.



Prospects for highly efficient engine systems and goals: (Professor Taisei, Waseda University Research Institute)

Passenger vehicle sales
forecast by IEA/ETP
(Passenger vehicle sales forecast by IEA/ETP (2012): Created by MarkLines based on Professor Taisei's documents)
Note) IEA/ETP: International Energy Agency/Energy Technology Perspectives

  A lecture was given by Waseda University regarding the "Possibilities of reducing CO2 by an additional 30% by 2030," determined by the history of automobile fuel efficiency improvement technology in Japan up to the present.

  • Gasoline engine thermal efficiency improvement: 35-40%⇒45-50% (diesel engines: 35-45%⇒50-55%)
  • Improvement of partial load fuel consumption
  • Utilization of exhaust heat
  • Reaping results from SIP "innovative combustion technology"

(Note): SIP = the Strategic Innovation Promotion Program, a program lead by top officials in the Japanese government.

The above items will advance in the next ten years, and 90% of global vehicle sales in the 2030s will consist of vehicles with highly efficient engines.


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Key words

IC, ICE, e-Power, VC-Turbo, electrification, PHEV, HEV, FCV, BEV, EV, Toyota, Honda, Nissan, Mazda

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