Mohammad Pournazeri - Academia.edu (original) (raw)

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Papers by Mohammad Pournazeri

Research paper thumbnail of Improving energy efficiency and robustness of a novel variable valve actuation system for engines

Research paper thumbnail of Development of a new fully flexible hydraulic variable valve actuation system for engines using rotary spool valves

Research paper thumbnail of Precise lift control in a new variable valve actuation system using discrete-time sliding mode control

Mechanism and Machine Theory

Research paper thumbnail of A Robust Variable Valve Actuation System With Energy Recovery Mechanism

ASME 2012 Internal Combustion Engine Division Spring Technical Conference, 2012

Research paper thumbnail of A Cam-Based Electro-Hydraulic Variable Valve Timing System for Pneumatic Hybrid Engines

Volume 13: New Developments in Simulation Methods and Software for Engineering Applications; Safety Engineering, Risk Analysis and Reliability Methods; Transportation Systems, 2009

Research paper thumbnail of A Robust Lift Control Technique in Electro-Hydraulic Camless Valves Using System Average Model

Volume 8: Dynamic Systems and Control, Parts A and B, 2010

Research paper thumbnail of Air Hybrid Engine Torque Control Using Adaptive Sliding Mode Control

Volume 8: Dynamic Systems and Control, Parts A and B, 2010

ABSTRACT In this work, a new air hybrid engine configuration is introduced in which two throttles... more ABSTRACT In this work, a new air hybrid engine configuration is introduced in which two throttles are used to manage the engine load in three modes of operation i.e. braking, air motor, and conventional mode. A Mean Value Model (MVM) of the engine is developed at braking mode and a new Adaptive Sliding Mode Controller (ASMC), recently proposed in the literature, is applied to control the engine torque at this mode. The results show that the controller performs remarkably well in terms of the robustness, tracking error convergence and disturbance attenuation. Chattering effect is also removed by utilizing the ASMC scheme.

Research paper thumbnail of Regenerative braking torque control of air hybrid engines with cam-based valvetrains

International Journal of Powertrains, 2011

In this work, a novel air hybrid engine configuration is introduced in which cam-based valvetrain... more In this work, a novel air hybrid engine configuration is introduced in which cam-based valvetrain along with three-way and unidirectional valves make the implementation of different engine operational modes possible. In the proposed configuration, an electronic ...

Research paper thumbnail of A New Valve Lift Control Technique in Electrohydraulic Variable Valve Actuation Systems

ASME 2010 Internal Combustion Engine Division Fall Technical Conference, 2010

Research paper thumbnail of An Efficient Lift Control Technique in Electro-hydraulic Camless Valvetrain Using Variable Speed Hydraulic Pump

SAE International Journal of Engines, 2011

Significant improvement in fuel consumption, torque delivery and emission could be achieved throu... more Significant improvement in fuel consumption, torque delivery and emission could be achieved through flexible control of the valve timings, duration and lift. In most existing electrohydraulic variable valve actuation systems, the desired valve lift within every engine cycle is achieved by accurately controlling of the solenoid-valve opening interval; however, due to slow response time, precision control of these valves is difficult particularly during higher engine speeds. In this paper a new lift control strategy is proposed based on the hydraulic supply pressure and flow control. In this method, in order to control the peak valve lift, the hydraulic pump speed is precisely controlled using a two-input gearbox mechanism. This eliminates the need for precision control of the solenoid valves opening interval within every cycle. To achieve a smooth control signal, it is worthwhile to control the maximum valve lift within few engine cycles rather than every cycle; therefore, instead of using the governing nonlinear differential equations of the mechanism, a novel average model of the system is developed based on energy conservation equations. A non-linear sliding mode controller (SMC) is also designed based on the developed average model and the boundary layer method is used to eliminate the chattering problem. The performance of the proposed controller is then examined through some simulations. Moreover, the new lift control technique is implemented experimentally by reconfiguration of the existing electro-hydraulic valve system prototype and empirical results are then compared with those obtained from the simulations.

Research paper thumbnail of Diesel EGR fuel reformer improvement with flow reversal and central fueling

SAE Technical Papers, 2008

Abstract Empirical work has been conducted with an EGR fuel reformer configured in a flow reversa... more Abstract Empirical work has been conducted with an EGR fuel reformer configured in a flow reversal and central fueling embedment to improve the fuel dispersion quality and the reforming energy efficiency. Comprehensive comparison analyses are made between the ...

Research paper thumbnail of A new electro-hydraulic valvetrain configuration with improved lift controllability

International Journal of Powertrains, 2012

Research paper thumbnail of A Novel Air Hybrid Engine Configuration Utilizing Cam-Based Valvetrain

SAE Technical Paper Series, 2011

Abstract In this work, a new air hybrid engine configuration is introduced in which cam-based val... more Abstract In this work, a new air hybrid engine configuration is introduced in which cam-based valvetrain along with three-way and unidirectional valves make the implementation of different air hybrid engine operational modes possible. This configuration simplifies the air ...

Research paper thumbnail of An Efficient Lift Control Technique in Electro-hydraulic Camless Valvetrain Using Variable Speed Hydraulic Pump (2011-01-0940)

Significant improvement in fuel consumption, torque delivery and emission could be achieved throu... more Significant improvement in fuel consumption, torque delivery and emission could be achieved through flexible control of the valve timings, duration and lift. In most existing electrohydraulic variable valve actuation systems, the desired valve lift within every engine cycle is achieved by accurately controlling of the solenoid-valve opening interval; however, due to slow response time, precision control of these valves is difficult particularly during higher engine speeds. In this paper a new lift control strategy is proposed based on the hydraulic supply pressure and flow control. In this method, in order to control the peak valve lift, the hydraulic pump speed is precisely controlled using a two-input gearbox mechanism. This eliminates the need for precision control of the solenoid valves opening interval within every cycle. To achieve a smooth control signal, it is worthwhile to control the maximum valve lift within few engine cycles rather than every cycle; therefore, instead of using the governing nonlinear differential equations of the mechanism, a novel average model of the system is developed based on energy conservation equations. A non-linear sliding mode controller (SMC) is also designed based on the developed average model and the boundary layer method is used to eliminate the chattering problem. The performance of the proposed controller is then examined through some simulations. Moreover, the new lift control technique is implemented experimentally by reconfiguration of the existing electro-hydraulic valve system prototype and empirical results are then compared with those obtained from the simulations.

Research paper thumbnail of Improving energy efficiency and robustness of a novel variable valve actuation system for engines

Research paper thumbnail of Development of a new fully flexible hydraulic variable valve actuation system for engines using rotary spool valves

Research paper thumbnail of Precise lift control in a new variable valve actuation system using discrete-time sliding mode control

Mechanism and Machine Theory

Research paper thumbnail of A Robust Variable Valve Actuation System With Energy Recovery Mechanism

ASME 2012 Internal Combustion Engine Division Spring Technical Conference, 2012

Research paper thumbnail of A Cam-Based Electro-Hydraulic Variable Valve Timing System for Pneumatic Hybrid Engines

Volume 13: New Developments in Simulation Methods and Software for Engineering Applications; Safety Engineering, Risk Analysis and Reliability Methods; Transportation Systems, 2009

Research paper thumbnail of A Robust Lift Control Technique in Electro-Hydraulic Camless Valves Using System Average Model

Volume 8: Dynamic Systems and Control, Parts A and B, 2010

Research paper thumbnail of Air Hybrid Engine Torque Control Using Adaptive Sliding Mode Control

Volume 8: Dynamic Systems and Control, Parts A and B, 2010

ABSTRACT In this work, a new air hybrid engine configuration is introduced in which two throttles... more ABSTRACT In this work, a new air hybrid engine configuration is introduced in which two throttles are used to manage the engine load in three modes of operation i.e. braking, air motor, and conventional mode. A Mean Value Model (MVM) of the engine is developed at braking mode and a new Adaptive Sliding Mode Controller (ASMC), recently proposed in the literature, is applied to control the engine torque at this mode. The results show that the controller performs remarkably well in terms of the robustness, tracking error convergence and disturbance attenuation. Chattering effect is also removed by utilizing the ASMC scheme.

Research paper thumbnail of Regenerative braking torque control of air hybrid engines with cam-based valvetrains

International Journal of Powertrains, 2011

In this work, a novel air hybrid engine configuration is introduced in which cam-based valvetrain... more In this work, a novel air hybrid engine configuration is introduced in which cam-based valvetrain along with three-way and unidirectional valves make the implementation of different engine operational modes possible. In the proposed configuration, an electronic ...

Research paper thumbnail of A New Valve Lift Control Technique in Electrohydraulic Variable Valve Actuation Systems

ASME 2010 Internal Combustion Engine Division Fall Technical Conference, 2010

Research paper thumbnail of An Efficient Lift Control Technique in Electro-hydraulic Camless Valvetrain Using Variable Speed Hydraulic Pump

SAE International Journal of Engines, 2011

Significant improvement in fuel consumption, torque delivery and emission could be achieved throu... more Significant improvement in fuel consumption, torque delivery and emission could be achieved through flexible control of the valve timings, duration and lift. In most existing electrohydraulic variable valve actuation systems, the desired valve lift within every engine cycle is achieved by accurately controlling of the solenoid-valve opening interval; however, due to slow response time, precision control of these valves is difficult particularly during higher engine speeds. In this paper a new lift control strategy is proposed based on the hydraulic supply pressure and flow control. In this method, in order to control the peak valve lift, the hydraulic pump speed is precisely controlled using a two-input gearbox mechanism. This eliminates the need for precision control of the solenoid valves opening interval within every cycle. To achieve a smooth control signal, it is worthwhile to control the maximum valve lift within few engine cycles rather than every cycle; therefore, instead of using the governing nonlinear differential equations of the mechanism, a novel average model of the system is developed based on energy conservation equations. A non-linear sliding mode controller (SMC) is also designed based on the developed average model and the boundary layer method is used to eliminate the chattering problem. The performance of the proposed controller is then examined through some simulations. Moreover, the new lift control technique is implemented experimentally by reconfiguration of the existing electro-hydraulic valve system prototype and empirical results are then compared with those obtained from the simulations.

Research paper thumbnail of Diesel EGR fuel reformer improvement with flow reversal and central fueling

SAE Technical Papers, 2008

Abstract Empirical work has been conducted with an EGR fuel reformer configured in a flow reversa... more Abstract Empirical work has been conducted with an EGR fuel reformer configured in a flow reversal and central fueling embedment to improve the fuel dispersion quality and the reforming energy efficiency. Comprehensive comparison analyses are made between the ...

Research paper thumbnail of A new electro-hydraulic valvetrain configuration with improved lift controllability

International Journal of Powertrains, 2012

Research paper thumbnail of A Novel Air Hybrid Engine Configuration Utilizing Cam-Based Valvetrain

SAE Technical Paper Series, 2011

Abstract In this work, a new air hybrid engine configuration is introduced in which cam-based val... more Abstract In this work, a new air hybrid engine configuration is introduced in which cam-based valvetrain along with three-way and unidirectional valves make the implementation of different air hybrid engine operational modes possible. This configuration simplifies the air ...

Research paper thumbnail of An Efficient Lift Control Technique in Electro-hydraulic Camless Valvetrain Using Variable Speed Hydraulic Pump (2011-01-0940)

Significant improvement in fuel consumption, torque delivery and emission could be achieved throu... more Significant improvement in fuel consumption, torque delivery and emission could be achieved through flexible control of the valve timings, duration and lift. In most existing electrohydraulic variable valve actuation systems, the desired valve lift within every engine cycle is achieved by accurately controlling of the solenoid-valve opening interval; however, due to slow response time, precision control of these valves is difficult particularly during higher engine speeds. In this paper a new lift control strategy is proposed based on the hydraulic supply pressure and flow control. In this method, in order to control the peak valve lift, the hydraulic pump speed is precisely controlled using a two-input gearbox mechanism. This eliminates the need for precision control of the solenoid valves opening interval within every cycle. To achieve a smooth control signal, it is worthwhile to control the maximum valve lift within few engine cycles rather than every cycle; therefore, instead of using the governing nonlinear differential equations of the mechanism, a novel average model of the system is developed based on energy conservation equations. A non-linear sliding mode controller (SMC) is also designed based on the developed average model and the boundary layer method is used to eliminate the chattering problem. The performance of the proposed controller is then examined through some simulations. Moreover, the new lift control technique is implemented experimentally by reconfiguration of the existing electro-hydraulic valve system prototype and empirical results are then compared with those obtained from the simulations.