Modelling and optimizing two- and four-stroke hybrid pneumatic engines

Abstract

Hybrid pneumatic engines, which are designed to follow the downsizing and supercharging paradigm, offer a fuel-saving potential that is almost equal to that of hybrid electric powertrains while inducing much lower additional mass and cost penalties. This paper presents a systematic optimization of the operation of such an engine system. Both two-stroke and four-stroke modes are analysed. The optimized valve and throttle actuation laws for all modes and operating areas lead to generic maps that are independent of the engine size. So far, the pneumatic hybridization of internal combustion engines was thought to require two-stroke operation. This paper presents a novel hybrid pneumatic engine configuration that entails fixed camshafts for both intake and exhaust valves while utilizing variable valve actuation for one charge valve per cylinder only. This configuration is operated entirely in four-stroke modes. Such a configuration requires a careful optimization of its operating strategy to achieve its fuel economy potential. Compared with a full two-stroke operation, only small efficiency losses result from using four-stroke modes with these new operating strategies. Initial measurement results with such an engine system are presented in this paper to confirm the validity of the principles of operation.

Keywords

modelling optimization hybrid pneumatic engines

Get full access to this article

View all access options for this article.

References

Schechter

‘New cycles for automobile engines.’ SAE paper 1999–01-0623, 1999

Higelin

Charlet

Chamaillard

‘Thermodynamic simulation of a hybrid pneumatic combustion engine concept.’

Int. J. Appl. Thermodynamics 5 (1) (2002): 1–11

Tai

Tsao

T. C.

Levin

M. B.

Schechter

‘Using camless valvetrain for air hybrid optimization.’ SAE paper 2003–01-0038, 2003

Andersson

‘An air hybrid for high power absorption and discharge.’

SAE paper 2005–01-2137 (2005)

Vasile

Higelin

Charlet

Chamaillard

‘Downsized engine torque lag compensation by pneumatic hybridization.’ In Proceedings of the Conference on

Modelling Fluid Flow (CMFF ‘06), 13th International Conference on Fluid Flow Technologies, Budapest, Hungary, 6–9 September 2006

Dönitz

Vasile

Onder

Guzzella

Higelin

Charlet

Chamaillard

‘Pneumatic hybrid internal combustion engine on the basis of fixed camshafts.’ Eur. Pat. Applic. EP07018673.9, 2007

Higelin

Vasile

Charlet

Chamaillard

‘Parametric optimization of a new hybrid pneumatic combustion engine concept.’

Int. J. Engine Res. 5 (2) (2004): 205–217

Blumberg

P. N.

‘Features of a combined model of a camless 4-stroke internal combustion engine and 2-stroke air compressor/air-motor with pneumatic storage.’ In Proceedings of the GT-Suite Users Conference, 2004

Kang

Tai

Wang

Tsao

T. C.

Blumberg

P. N.

Stewart

‘Demonstration of air-power-assist (APA) engine technology for clean combustion and direct energy recovery in heavy-duty application.’ SAE paper 2008–01-1197, 2008.

10.

Trajkovic

Tunestal

Johansson

‘Investigation of different valve geometries and valve timing strategies and their effect on regenerative efficiency for a pneumatic hybrid with variable valve actuation.’ SAE paper 2008–01-1715, 2008.

11.

Sundström

Guzzella

Soltic

‘Optimal hybridization in two parallel hybrid electric vehicles using dynamic programming.’ In Proceedings of the 17th IFAC World Congress, Seoul, Republic of Korea, 6-11 July 2008.

12.

Serrao

Chehab

Guezennec

Rizzoni

‘An aging model of Ni—MH batteries for hybrid electric vehicles.’ In Proceedings of the IEEE Vehicle Power and Propulsion Conference 2005, pp. 78–85 (IEEE, New York).

13.

Guzzella

Sciarretta

Vehicle propulsion systems, 2nd edition (Berlin

Springer-Verlag

2007)

14.

Guzzella

Onder

C. H.

Introduction to modeling and control of internal combustion engine systems (Berlin

Springer-Verlag

2004)