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  • 1.
    Agrell, Fredrik
    KTH, Superseded Departments, Machine Design.
    Control of HCCI by aid of variable valve timings2003Licentiate thesis, comprehensive summary (Other scientific)
  • 2.
    Agrell, Fredrik
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Control of HCCI by aid of Variable Valve Timings with Specialization in Usage of a Non-Linear Quasi-Static Compensation2006Doctoral thesis, comprehensive summary (Other scientific)
    Abstract [en]

    This doctoral thesis is about controlling the combustion timing of the combustion concept Homogeneous Charge Compression Ignition, HCCI, by means of variable valve timings.

    The HCCI research usually is regarded to have started in Japan during the later part of the 1970´s. The world of HCCI has since grown and HCCI is of today researched worldwide. Of particular interest from a Swedish point of view is that Lund Institute of Technology has emerged as one of the world leading HCCI laboratories.

    The idea with HCCI is to combine the Otto and Diesel engine. As in an Otto engine the charge is premixed but as in a Diesel engine the operation is unthrottled and the compression heat causes the ignition. The combustion that follows the ignition takes place homogeneously and overall lean. The result is ultra low NOx and particulate emissions combined with high total efficiency. A difficulty with the HCCI-concept is that it only works in a narrow area and that there is no direct way to control the Start Of Combustion, SOC. Out of this follows that timing/phasing of the combustion is one of the main difficulties with HCCI combustion concepts. This is particularly emphasized during transient operation and calls for feedback control of the combustion timing.

    This work investigates one method, the variable valve timing, to achieve feedback control of the combustion phasing. From the work it can be concluded that the variable valve timing can control the combustion phasing during engine transients. In order to improve the performance a non-linear compensation from ignition delay to valve timings has been suggested, incorporated in a control structure and tested in engine test. The engine test has been performed in a single cylinder engine based on a Scania truck engine. The speed range from 500 to 1750 rpm and the load range 1.26 and 10.5 bar of netIMEP has been covered with fair transient performance.

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  • 3.
    Agrell, Fredrik
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Ångström, Hans-Erik
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Eriksson, Bengt
    Wikander, Jan
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Linderyd, Johan
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Control of HCCI During Engine Transients by aid of Variable Valve Timings Through the use of Model Based Non-Linear Compensation2005In: SAE transactions, ISSN 0096-736X, Vol. 114, no 3, p. 296-310Article in journal (Refereed)
    Abstract [en]

    One of the main challenges with the Homogeneous Charge Compression Ignition, HCCI, combustion system is to control the Start Of Combustion, SOC, for varying load and external conditions. A method to achieve this on a cycle-by-cycle basis is to vary the valve timing based on a feedback signal from the SOC of previous cycles. The control can be achieved with two basic valve-timing strategies named the Overlap- and the IVC-method. The Overlap-method works by trapping of residuals while the IVC-method affects the effective compression ratio. In an earlier paper it has been shown that if the two methods are incorporated into one controller, SOC can be controlled in a relatively large operating window although the transient performance was not sufficient. The reason is that the simple PI-controller cannot be made fast enough to cope with the transients without magnifying the cycle-to-cycle variations of the combustion into instability. In this work a model based control system that features a non-linear compensation, based on the inverse of the non-linear function from valve timings to ignition delay, is suggested and evaluated. The results show good transient performance. Control performance from engine tests is reported. A combined engine and control simulation system is used for the development of the control strategies. The simulations are accomplished with a commercial cycle simulation code linked with a commercial control simulation code. The simulations are iteratively verified against engine test data. Engine tests are conducted on a single cylinder engine equipped with a hydraulic valve system.

  • 4.
    Agrell, Fredrik
    et al.
    KTH, Superseded Departments, Machine Design.
    Ångström, Hans-Erik
    KTH, Superseded Departments, Machine Design.
    Eriksson, Bengt
    Wikander, Jan
    KTH, Superseded Departments, Machine Design.
    Linderyd, Johan
    Integrated Simulation and Engine Test of Closed Loop HCCI Control by aid of Variable Valve Timings2003In: SAE transactions, ISSN 0096-736X, Vol. 112, no 3, p. 1078-1091Article in journal (Refereed)
  • 5.
    Agrell, Fredrik
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Ångström, Hans-Erik
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Eriksson, Bengt
    Wikander, Jan
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Linderyd, Johan
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Practical Modeling of HCCI for Combustion Timing Control and Results from Engine Test2005In: KTH Internal Combustion Engine Report MFM, Vol. 162Article, review/survey (Refereed)
  • 6.
    Agrell, Fredrik
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Ångström, Hans-Erik
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Eriksson, Bengt
    Wikander, Jan
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Linderyd, Johan
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Transient Control of HCCI Combustion by aid of Variable Valve Timing Through the use of a Engine State Corrected CA50-Controller Combined with an In-Cylinder State Estimator Estimating Lambda2005Conference paper (Refereed)
    Abstract [en]

    One of the main challenges with the Homogeneous Charge Compression Ignition, HCCI, combustion system is to control the Start Of Combustion, SOC, for varying load and external conditions. A method to achieve this on a cycle-by-cycle basis is to vary the valve timing based on a feedback signal from the SOC of previous cycles. The control can be achieved with two basic valve-timing strategies named the Overlap- and the IVC-method. The Overlap-method works by trapping of residuals while the IVC-method affects the effective compression ratio

  • 7.
    Agrell, Fredrik
    et al.
    KTH, Superseded Departments, Machine Design.
    Ångström, Hans-Erik
    KTH, Superseded Departments, Machine Design.
    Eriksson, Bengt
    Wikander, Jan
    KTH, Superseded Departments, Machine Design.
    Linderyd, Johan
    Transient Control of HCCI Through Combined Intake and Exhaust Valve Actuation2003Conference paper (Refereed)
    Abstract [en]

    Homogeneous Charge Compression Ignition, HCCI, has the attractive feature of low particulate emission and low Nitrogen Oxides, NOx, emission combined with high efficiency. The principle is a combination of an Otto and a Diesel engine in that a premixed charge is ignited by the compression heat.

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