Advanced Gasoline Engine Turbocharging Technology for Fuel Economy Improvements

a b s t r a c tIncreasingly stringent emissions legislation combined with consumer performance demand has created the need for complex automotive engines. The control of this complex system relies heavily on control oriented models. Models capable of describing all operating modes of the systems are beneficial, and the models should be easily parametrized and enable extrapolation. A large database of automotive compressor maps is characterized, and used to develop, validate and automatically parametrize a compressor flow model capable of describing reversed flow, normal operation and choke. Measurement data from both an engine test stand and a surge test stand is used to parametrize and validate the surge capability of the model. The model is shown to describe all modes of operation with good performance, and also to be able to extrapolate to small turbo speeds. The extrapolation capability is important, since compressor maps are shown to lack information for low speeds, even though they frequently operate there in an engine installation.

Section: Introductionmentioning

confidence: 99%

A surge and choke capable compressor flow model—Validation and extrapolation capability

Leufvén

Eriksson

2013

“…The main goal is to decrease fuel consumption and emissions, while keeping the performance of the engine constant. A way of achieving this goal is the introduction of turbocharging (Emmenthal, Hagermann, & Hucho, 1979;Guzzella, Wenger, & Martin, 2000;Petitjean, Bernardini, Middlemass, Shahed, & Hurley, 2004). Lately, more than one turbo has been added to increase flexibility.…”

Section: Introductionmentioning

confidence: 99%

Modeling and validation of a boost pressure actuation system, for a series sequentially turbocharged SI engine

Thomasson

Leufvén

Criscuolo

et al. 2013

a b s t r a c tAn actuation system for flexible control of an advanced turbocharging system is studied. It incorporates a vacuum pump and tank that are connected to pulse width modulation controlled vacuum valves. A methodology for modeling the entire boost pressure actuation system is developed. Emphasis is placed on developing component models that are easily identified from measured data, without the need for expensive measurements.The models have physical interpretations that enable handling of varying surrounding conditions.The component models and integrated system are evaluated on a two stage series sequential turbo system with three actuators having different characteristics.Several applications of the developed system model are presented, including a nonlinear compensator for voltage disturbance rejection where the performance of the compensator is demonstrated on an engine in a test cell. The applicability of the complete system model for control and diagnosis of the vacuum system is also discussed.

“…This is beneficial in low-to mid-load operating points where the engine usually operates, since pumping and friction losses are reduced, Guzzella et al (2000). More advanced turbocharging concepts are being developed to further increase power density, Petitjean et al (2004). A configuration that has increased in popularity is the use of two parallel identical turbochargers for V-type engines, one powered by each bank of cylinders.…”

Section: Introductionmentioning

confidence: 99%

Co-surge in bi-turbo engines: Measurements, analysis and control

Thomasson

Eriksson

2014

In parallel turbocharged V-engines, with two separate air paths connected before the throttle, an oscillation in the flow can occur. If the compressor operates close to the surge line, typically during low speed and high load, and a disturbance alters the mass flow balance, the compressors can begin to alternately go into surge. This phenomenon is called co-surge and is unwanted due to high noise and risk for turbocharger destruction. Co-surge is measured on a test vehicle in a chassis dynamometer and the system analyzed and modeled using a mean value engine model. The investigation shows that the alternating compressor speeds have an important role in the prolonged oscillation. A reconstruction of the negative flow from measurements is made and compared to simulation results, showing similar amplitudes, and supports the model validation. A new co-surge detection algorithm is presented, suitable for a pair of sensors measuring either mass flow, boost pressure or turbo speed in the two air paths. Furthermore, a new controller is proposed that uses a model based feedforward for the throttle, together with wastegate actuation to force the compressor speeds together and improve balance at the recovery point. This has shown to be sufficient with moderate to high pressure ratios over the throttle, only for zero or very low pressure drop the use of bypass valves are necessary. The advantage of not opening the bypass valves is a smaller drop in boost pressure which also reduces the torque disturbance. The performance of the controller is evaluated both in simulation and in the test vehicle.