Ignition Control of Advanced Combustion Engines - A ...

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Recent Patents on Mechanical Engineering 2009, 2, 154-164

Ignition Control of Advanced Combustion Engines - A Patent Landscape Chellapilla Kameswara Rao* Hi-Tech College of Engineering & Technology, Gandipet-Himayatnagar, Hyderabad, Andhra Pradesh, India Received: January 23, 2009; Accepted: March 27, 2009; Revised: April 30, 2009

Abstract: Global research and development on an innovative engine concept known as Homogeneous Charge Compression Ignition (HCCI) is being pursued aggressively and the gas engines employing this concept are expected to become commercially viable soon. The U.S. government is expected to institute the emission standard by 2009 and the same needs to be complied thereafter. Gas engines using HCCI will be gaining around 20 percent in fuel consumption. The present paper aims at mapping the patented technologies related to this engine concept. Global patent search retrieved a total of 171 patent families and an attempt is made in this paper to undertake mapping of these patents to get a clear idea about the major players in this area, technologies developed and country-wise patenting activity.

Keywords: Advanced combustion engines, homogeneous charge compression ignition (HCCI), ignition control & gas engines. INTRODUCTION Combining features of spark ignition (SI) and diesel engines both, the HCCI engine is promising the high efficiency of a diesel engine with virtually no NOx or particulate emissions. The engine can operate using a variety of fuels. Given this mix of attributes, it is not surprising that considerable research is going on around the world on the HCCI engine. Many annual and introductory reports [1-7] are made available in the open literature on the extensive sponsored research studies being made by several automotive industry leaders and University research laboratories in the area of HCCI engine development. Several studies [8-11] are focused on developing suitable fuel injection and ignition control strategies. Developing and controlling alternative fuels [12-17] is also extensively undertaken. Numerical modeling and simulation of combustion in HCCI engines is also undertaken by several researchers [18-26]. Effects of negative overlap and variable valve timing are also investigated [27-30]. HCCI BACKGROUND In the HCCI engine, fuel is homogeneously premixed with air, as in a spark-ignited engine, but with a high proportion of air to fuel. When the piston reaches its highest point, this lean fuel auto-ignites i.e., spontaneously combusts, from compression heating, as in a diesel engine. But it is this auto-ignition which causes knock in a spark-ignited engine. Knock is undesirable in spark-ignited engines because it enhances heat transfer within the cylinder and may burn or damage the piston. But, in a HCCI engine, with its high air-to-fuel ratio, knock does not damage the engine because the presence of excess air keeps the maximum temperature of the burned gases relatively low. When the *Address correspondence to this author at the Hi-Tech College of Engineering & Technology, Gandipet-Himayatnagar, C.B. Post, Hyderabad - 500075, Andhra Pradesh, India; Tel: 91-40-23811623; Mobile: 91-09849198548; E-mail: [email protected]

1874-477X/09 $100.00+.00

danger of engine damage is eliminated, auto-ignition becomes a desirable mode of operation. During mid-1990s, researchers realized that understanding chemical kinetics was the key to control HCCI combustion. This realization, combined with the access to detailed chemical kinetics codes such as HCT (hydrodynamics, chemistry, and transport), quickly resulted in experimental and theoretical analysis of HCCI combustion with an ultimate aim to gain control in efficiently running gas engines using this concept. A single-cylinder HCCI engine has been operating at the University of Berkeley campus and producing data since April 1999. A four-cylinder diesel engine is modified as an HCCI engine and the data from the theoretical models tallied very well with experimental results obtained on this engine. Auto-ignition must occur almost exactly at the point where the piston reaches its maximum height within the cylinder. Timing of auto-ignition is thus critical, but the HCCI engine gives up two timing control mechanisms: The start of ignition is not directly controlled by an external event such as the beginning of injection in the standard diesel or the sparking of the spark plug; and the heat release rate is not controlled by either the rate and duration of the fuel-injection process, as in the diesel engine, or by the turbulent flame propagation time, as in the spark-ignited engine. Detailed modeling of engines using a homogeneous charge of various fuels has shown that by knowing the precise conditions (fuel species, temperature, and density) at the start of compression, the beginning of combustion can be accurately predicted. But the control problem is what is keeping the HCCI engine out of the auto showroom and the researchers’ world over are innovating on various options. One option is to inject re-circulated exhaust gases (EGR) into the fuel-air mixture to raise the fuel temperature quickly. Another option is to use small amounts of dimethyl ether to enhance ignition slightly. In the present paper an attempt has been made to present results of a global patent search carried out for ignition control technologies related to the advanced combustion © 2009 Bentham Science Publishers Ltd.

Advanced Combustion Engines

Recent Patents on Mechanical Engineering 2009, Vol. 2, No. 2

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engines based on Homogeneous Charge Compression Ignition (HCCI), Premixed Charge Compression Ignition (PCCI), Reformed Charge Compression Ignition (RCCI) and Stratified Charge Compression Ignition (SCCI) concepts. Global patent search retrieved a total of 171 patent families in this area and an attempt is made in this paper to undertake mapping of these patent records to get a clear idea about the major players in this area, technologies developed and country-wise patenting activity.

11. General Motors Corp. (4)

BIBLIOGRAPHIC DATA

MINOR ASSIGNEES

Figures 1 & 2 show the priority of year wise patent filing activity. From this data we can see that the patent filing in HCCI engines started some where in 1997 and started progressively increasing up to the year 2004. In the year 2004 around 47 patent applications were filed and this is a sign of gearing up of automotive companies to face the challenge of meeting the US emissions standards to be implemented from 2009 as envisaged.

Assignees having two records are: Mendler, Cummins Engine Company, Inc., Daimlerchrysler Ag,Energy U.S. Department, Lotus Cars Limited, Avl List Gmbh, Mazda Motor Company.

MAJOR ASSIGNEES From Fig. (2), major assignees can be seen as: 1.

Ford Global Tech. (28)

2.

Caterpillar Inc. (16)

3.

GM Global Tech. (10)

4.

Honda Motor Co. Ltd. (6)

5.

Southwest Research Institute (6)

6.

International Engine IP Company (7)

7.

Kabushiki Kaisha.(5)

8.

Siemens AG. (4)

9.

Siemens Aktiengesollschaft (4)

10. Toyota Industries Corporation (4)

Fig. (1). Priority Year vs. Number of Patents.

12. Scania Cv Ab (Publ) (4) 13. US Environmental (3) 14. Yamaha Motor Co. Ltd. (4) 15. AVI List GMBH (4) Numbers in brackets designate number of patent filed by them.

ASSIGNEES HAVING ONE RECORD EACH Perkins Engines Company Limited, Pattakos, Manousos, US Environmental Protection Agency, The Nippon Oil Corporation, Clean Air Partners, Inc., Sandia National Laboratories, Massachusetts Institute of Technology, Suzuki Motor Corp, Chevron U.S.A. Inc., Lew Holdings, Llc, Exxonmobil Research and Engineering Company, Janhunen, Timo, Tapani, Agilepower Systems, Inc., Ut Battelle, Llc, Visteon Global Technologies, Inc., Thomas Tsoi Hei Ma, Hitachi, Ltd., Heyder, Michael, Hatamura Koichi, Bank of America, N.A., As Administrative Agent, Aspen Engineering Services, Llc, Robert Bosch Gmbh, Idemitsu Kosan Co Ltd, Tiax, Llc, Inst Fr Petrole, Lin-Shu Wang, The Regents of The University of California, Delphi Technologies, Inc., Wisconsin Alumni Research Foundation, Renault S.A.S Société Par Actions Simplifiée, Shell Oil Company, C.R.F. Societa Consortile Per Azioni, Shell International Research Maatschappij B.V., Peugeot Citroën Automobiles S.A., Sasol Technology (Pty) Limited.

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Chellapilla K. Rao

Fig. (2). Priority Year vs. Assignee vs. Number of Patents.

CITATION VELOCITY STUDY US5875743 [31] patent, issued in 1999 to Southwest Research Institute has been found to have an average citation velocity of 9.7 per year. Next patent, US6276334 [32] issued in 2001 to Cummins Engine Company Inc., has got an average citation velocity of 9.6 per year. US6390054 [33] patent issued in 2002 to Ford Global Technologies got an average citation velocity of 6.5 per year. INVENTOR TRACKING Yang Jialin of Ford Global Technologies filed 9 patent applications with his name as the first inventor. Out of these, five patents are granted and the rest four are published applications. Kuo Tang Wei of GM Global Technologies Operations Inc., filed a total of four US patent applications. Kamio Junichi of Honda Motor Co. Ltd., filed four US patent applications and one Japanese patent application. Liu Zhengbai of International Engine IP Company filed three US patent applications out of which one is granted. Gray Charles, Hashimoto Kohtaro, Koopmans Lucien and Linderyd Johan filed two US patent applications each with their names as the first inventor. IPC AND US CLASS-WISE PATENT FILING From the detailed study of the patented literature, it appears that soon the HCCI engine control gains 20% higher efficiency and becomes commercially viable. Figures 3-7 presented below, show the number of patent records filed as per US classes and International Patent Classifications (IPC), respectively. In this regard it is not out of place to mention US President Bush’s request to his countrymen to reduce the fuel consumption in petrol engines by around 20% by the end of this decade, which means that clean diesel engines with negligible or no NOx emissions are required in

achieving this goal. US Department of Energy has taken considerable initiatives in financially supporting and promoting the research and development programs in this area involving many Universities and major original engine manufacturers (OEMs). The catalytic converters used today in spark-ignited gasoline automobiles are responsible for major reductions in tail-pipe emissions of carbon monoxide, hydrocarbons, and NOx. But that kind of catalysis does not work well on diesel engines, which operate on lean fuel-to-air mixtures. Exhausts from these engines contain an excessive amount of oxygen that inhibits the chemical reduction of NOx to nitrogen (N2), rendering catalytic converters useless for NOx removal. Lean-burn engines such as the diesel are the focus of most engine research today because they offer fuel economy unmatched by any other commercially viable engine. But they must run cleaner and produce fewer emissions if they are to gain more widespread use. While diesel engines can rather easily be optimized to reduce either NOx or particulate matter, cutting one usually causes an increase in the other. California's Air Resources Board and the U.S. Environmental Protection Agency are proposing regulations for substantially reducing emissions of NOx and particulate matter. These regulations will pose a major challenge for diesel engines, which currently produce significant amounts of both types of emissions. Given world over developing high profile lifestyle, it is clear that automobiles powered by the internal combustion engine are with us to stay, at least until some better mode of transportation comes along. For most consumers, the car's flexibility and relatively low cost outweigh its deleterious effects on petroleum reserves and the environment. But it is no accident that the US Department of Energy and other organizations are focusing most of their research on diesel and HCCI engines. These fuel-efficient engines promise to make oil supplies last longer. Once auto-ignition



Fig. (3). US Classes vs. Number of Patents.

Fig. (4). Priority Year vs. US Classes vs. Number of Patents. Some of the US classifications, which are mostly based on functionalities, pertinent to the present topic are as follows: 123: Internal-Combustion Engines 141: Fluent Material Handling 180: Motor Vehicles 208: Mineral Oils: Processes and products 261: Gas and liquid contact apparatus 701: Data Processing; Vehicles, navigation etc.

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Some of the important IPC classifications, which are based on technologies, are given below: F02B: Internal-combustion piston engines; F02D: Controlling combustion engines; F02M: Supplying combustion engines in general F01L: Cyclically operating valves for machines or engines; F02P: Ignition, other than compression ignition;

Fig. (5). Main IPC Classes vs. Number of Patents.

Fig. (6). Assignee vs. US Classes vs. Number of Patents.

Chellapilla K. Rao



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Fig. (7). Priority Year vs. IPC Classes vs. Number of Patents.

in the HCCI engine is effectively controlled, it may well be the engine we use until the fuel cell becomes an economic option. Developing fuels that burn cleaner and affect the environment less will improve the overall picture even more. Modeling engine processes is the key to this research. HCCI combustion engines require precise control of the in-cylinder mixture to be useful. One way of doing this is with completely flexible valve timing. This allows for the composition cylinder charges to be controlled for each cylinder and for each combustion event. Perhaps the most practical way to obtain variable valve timing is to use electromagnetic solenoid valves. However, these valves require feedback motion control in order to be robust to disturbances and achieve the low valve seating velocity needed for engine wear and noise requirements. MODELING OF HCCI COMBUSTION Single-zone or multi-zone models require initial conditions to be specified at (1) IVC (Inlet Valve Control), including (2) the average temperature, (3) pressure of the mixture, and, (4) each concentration of species (fuel) in the cylinder. These initial conditions are difficult to obtain in a test engine. Considering the importance of these initial conditions simulation accuracy, one-dimensional (1D) HCCI engine models combining both detailed combustion chemistry and gas exchange processes need to be developed so that the initial conditions at IVC (Inlet Valve Closing) no longer have to be set. Homogeneous Charge Compression Ignition (HCCI) combustion has advantages of thermal efficiency and low emissions and is becoming a promising combustion mode in internal combustion (IC) engines. However, HCCI still faces the challenges of (1) Ignition timing control, (2) Combustion rate control, and, (3) Operating range extension.

Thus the objectives of ongoing research in various universities are three fold: (1) Control of solenoid valve will provide a tremendous ability to examine interesting combustion phenomena in IC engines - including HCCI combustion; (2) Control of solenoid valves is an interesting control problem to exercise and develop new methodologies; (3) Combination of physically understanding electro-magnetic system, modeling them using finite element modeling and building a control oriented model for control design and designing the controller is typical to control design. This procedure is used for Electromagnetic Actuators and will also be used to help design effective actuators for the microfluidic application discussed above. Generally, HCCI engine cycle models are constructed by combining CHEMKIN code package and engine simulation code. The gas exchange process affects the engine parameters and charge properties and therefore plays a significant role in determining the control of the HCCI process. Therefore, 1D modeling is usually is used to analyze the influence of the variable valve timing strategy on the gas exchange process. In HCCI combustion, since there are no compulsive triggers, such as spark in traditional gasoline engines and fuel injection in diesel engines, optimization of combustion phase is more difficult than that in SI or diesel engines. HCCI combustion is mostly controlled by chemical kinetics. DATA ON GLOBAL PATENT FAMILIES HCCI is a low temperature chemically controlled (flameless) combustion process as traditional flame-based combustion concepts no longer apply. HCCI combustion is sensitive to changes in temperature, pressure, and fuel type making combustion control more complex and hence spark and injection timing no longer relevant In this paper patented technologies are studied using patent information available from paid as well as free databases. Patent landscape of all


patents filed on HCCI engine concept is studied with a special focus on technologies adopted for combustion and ignition control. Reducing to one per family, a total of 171 patents are used in mapping the Figs. (8) & (9), which are shown above. From the data mapped in these figures, we can find that 69 US patents are granted on HCCI technology and around 47 US patent applications are published. Granted EP patents are 10 and EP published applications are 31. Granted JP patents are 3 and 36 JP patent applications are published. PCT applications filed are a total of 58. Besides these, around 16 patents are granted in other countries, in addition to 81 published applications. This shows that globally the patenting activity is quite impressive in the area of HCCI engine technology and the activity is likely to increase further until technologies developed become commercially viable and cost effective. IGNITION TIMING Figure (10) shows the patented ignition control data mapped against Assignee versus priority year of patent filing. From these patented technologies, we can find that the ignition timing and combustion rate in the HCCI engine can be adjusted by (1) intake temperature (2) boost pressure, (3) compression ratio (4) Exhaust Gas Recirculation (EGR) ratio and (5) fuel property. In all these parameters, the temperature control usually has a slow response. Meanwhile, with the engine speed and load change, the ignition timing varies as well.

Fig. (8). Family Status vs. Number of Patents.

Chellapilla K. Rao

In order to control ignition timing, additional devices are needed, for instance, (1) dual-fuel with different ignition property, (2) mixing peroxide additive to improving ignition property, and (3) introducing a laser to stimulate HCCI ignition. But these methods or devices are not suitable for practical application on a commercial engine currently. COMBUSTION RATE To control HCCI combustion, several indirect control methods which influence HCCI combustion have been applied to gasoline HCCI investigation, including (1) air preheating, (2) supercharging (3) VCR (4) EGR etc. Stable HCCI combustion can be achieved at different operation conditions and HCCI engines can become commercial products only if a robust method with fast response and easy adjustment in engine operation are found. Three factors influence combustion which are; 1) Temperature, (2) Concentration and, (3) Components. If you consider Temperature -- it has a slow response to control. .However, it is possible to control the concentration and components precisely and rapidly. Figure 11 shows the patenting activity in temperature control area mapped against Assignee versus priority year. Using variable valve actuation (VVA) and negative valve overlap (NVO) type valve manipulation techniques; there are three methods to influence the auto-ignition process: (1) Achieving the in-homogeneity of temperature and concentration; (2) Distribution using direct fuel injection, (3) Introducing external energy such as laser stimulation or


Fig. (9). Priority Year vs. Family Status vs. Number of Patents.

Fig. (10). Ignition Control - Assignee vs. Priority Year.


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Chellapilla K. Rao

Fig. (11). Temperature Control - Assignee vs. Priority Year.

high- energy spark ignition, and fuel reforming to enhance the ignition property. Figures 12 and 13 show the patented Valve timing control and combustion control data mapped against Assignee versus priority year. CONCLUSIONS From the patent analysis presented in this paper, we can conclude the following: 1.

Patenting activity in the advanced combustion engines area started around 1997 or so and is steadily increasing since then. The engine control technology is still under improvement and may require five more years for maturing and for becoming commercially viable.

2.

All major global automotive companies such as Ford, Caterpillar, GM, Honda, Toyota, Siemens, Kabushiki Kaisha, Yamaha are actively innovating and filing patent applications.

3.

US Governments initiatives in encouraging, awarding and rewarding financial support in this area also resulted in an upward swift in patent filing and the year 2004 recorded the maximum number of patent filings.

4.

After US emissions standard gets implemented from the year 2009 onwards, surely by the year 2012 commercial vehicles may be launched by all the major innovating automotive companies thus maintaining competition in this important market area.

CURRENT & FUTURE DEVELOPMENTS A global patent search was carried out for ignition control technologies related to the advanced combustion

engines based on homogeneous charge compression ignition (HCCI), premixed charge compression ignition (PCCI), reformed charge compression ignition (RCCI) and stratified charge compression ignition (SCCI) concepts. The patent search retrieved a total of 171 patent families in this area and an attempt is made in this paper to undertake mapping of these patent records to get a clear idea about the major players in this area, technologies developed and countrywise patenting activity. The concept of HCCI is proven beyond doubt but many problems are yet to be solved in scaling up the same from the laboratory models to the ones to perform on the road in the commercial environment. The ignition and combustion control of these HCCI engine vehicles is becoming highly complicated in view of a variety of parameters involved. The mathematical modeling and the simulation of the ignition and combustion mechanisms and the development of suitable and efficient sensors for measuring and monitoring the same is in the focus of many of the patents reviewed and mapped in this paper. Many top-class automotive companies such as Ford Global Tech., Cummings Inc., GM Global Tech., International Engine IP., etc. are in the race to bring this concept to market as soon as possible. ACKNOWLEDGMENTS The independent and original research work reported in this paper was carried out when the author was working as Client Manager at SciTech Patent Art Services Private Limited. Author is highly grateful to the management of ScitTech Patent Art Services Private Limited, Hyderabad for all the support and encouragement received from them during the preparation of this paper. Author wants to spe-



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Fig. (12). Valve Timing Control - Assignee vs. Priority Year.

Fig. (13). Combustion Control - Assignee vs. Priority Year.

cially thank Mr. K. Venkataramana, for the help rendered by him in preparing the graphical illustrations presented in this paper.

This paper was presented by the author at the International Conference on Embedded Systems, Embedasia 2007, which was held at Bangalore, India during November 15-17, 2007. Author is grateful to SciTech Patent Art


Services Private Limited for financially sponsoring him for attending the Conference.

Chellapilla K. Rao [15]

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