Transient Control of a Camless Valve Actuation System Using a Time-Varying Repetitive Controller

2010 ◽  
Author(s):  
Pradeep Gillella ◽  
Zongxuan Sun
Keyword(s):  
Engine Speed ◽  
Combustion Engine ◽  
Sampling Rate ◽  
Control Design ◽  
Time Varying ◽  
Rotational Angle ◽  
Actuation System ◽  
Valve Motion ◽  
Actuation Systems ◽  
Valve Actuation

Camless valve actuation systems, also referred to as Fully Flexible Valve Actuation systems, use electronically controlled actuators to replace the camshaft in an internal combustion engine. This paper presents the control design for such an actuation system to enable the precise valve motion control during engine speed transients. The desired valve motion (reference) remains periodic in the crank angle domain, but becomes cyclic and aperiodic in the time domain when the engine speed changes in real-time. This phenomenon motivates the control design in the rotational angle domain. However, this approach results in a time-varying model for the plant. A systematic method for obtaining the discrete time-varying Input/Output representation of higher order systems is developed to enable the application of the newly developed time-varying repetitive control to plants with complex dynamics. The use of a variable sampling rate helps accurately represent complex reference signals using low dimensional models. The implementation of the simulations on a rapid control prototyping system helps identify and address potential issues that influence the controller execution time which directly affects the maximum engine speed at which it can be used.

Improved Mechanical Design for a Fully Variable Electromechanical Valve Actuation System for Internal Combustion Engines

2010 ◽  
Author(s):  
Hossein Rokni Damavandi Taher ◽  
Rudolf J. Seethaler ◽  
Abbas S. Milani
Keyword(s):  
Internal Combustion Engines ◽  
Mechanical Design ◽  
Experimental Tests ◽  
Internal Combustion ◽  
Combustion Engines ◽  
Mechanical Vibrations ◽  
Actuation System ◽  
Ohmic Losses ◽  
Valve Motion ◽  
Valve Actuation

This study aims to improve the mechanical design of a fully flexible valve actuation system (FFVA) for intake valves of internal combustion engines. Optimization procedures for increasing the reliability and efficiency of the mechanical design of the FFVA system are presented. Simulations and experimental tests are carried out in order to validate the system performance. It is shown that position, velocity and acceleration of the valve obtained by simulations are consistent with those observed experimentally. Furthermore, it is observed that the mechanical vibrations are considerably reduced in the redesigned FFVA system. As a result, current levels and ohmic losses in the electric motor are also reduced. The present redesigned FFVA system then provides more reliable valve motion and better efficiency than the previously shown design [25].

Simulation of a Camless Engine Valve Actuator With Mechanical Feedback

2008 ◽  
Author(s):  
Norman K. Bucknor
Keyword(s):  
Flow Control ◽  
Control Valve ◽  
Feedback Mechanism ◽  
Simulation Software ◽  
Flow Control Valve ◽  
Engine Valve ◽  
Valve Motion ◽  
Actuation Systems ◽  
Mechanical Feedback ◽  
Valve Actuation

Fully flexible engine valve actuation systems are enablers for improvements in engine fuel consumption and power delivery, as well as the implementation of advanced combustion strategies like homogeneous charge compression ignition (HCCI). Hydraulically actuated valve actuation systems provide the greatest operating flexibility but have generally required precision flow control (i.e., servovalves) for viable operation while consuming more power than conventional cam-driven valvetrains. This paper describes an electrohydraulic fully flexible engine valve actuator with a mechanical feedback linkage between the engine valve and the spool in the hydraulic flow control valve. This feedback linkage is intended to simplify the control of the engine valve motion and eliminate the need for servovalve-class performance in the hydraulic control valve. The feedback mechanism reduces the control effort needed to operate the flow control valve since the spool position is not solely a function of the control input. With the assistance of mechanical feedback, the flow through the control valve is throttled in proportion to the engine valve motion. Thus, while throttling losses are not eliminated, there is no excessive flow throttling. This will have a beneficial impact on the energy consumption of the actuator. For preliminary study and validation of the concept, a model of the actuator was developed using ADAMS mechanical system simulation software and AMESim hydraulic simulation software. Results for the combined mechano-hydraulic model are presented to illustrate potential performance benefits and pitfalls of the concept, including effects of dimensional tolerances in the flow control valve. The simulation data was also used to size an electromechanical actuator that would be used to the flow control valve in conjunction with the feedback mechanism.

Optimal Slip Control of a Torque Converter Clutch

2015 ◽  
Author(s):  
Yaoying Wang ◽  
Zongxuan Sun
Keyword(s):  
Engine Speed ◽  
Control Method ◽  
Torque Converter ◽  
Time Varying ◽  
Rotational Angle ◽  
Engine Torque ◽  
Slip Control ◽  
Energy Saving Potential ◽  
Vehicle Engine ◽  
Simulation Results

Slip control of a torque converter clutch (TCC) has been developed for years but most approaches are focused on time-based methods without offering a systematic approach for dealing with the time-varying signals associated with the engine torque pulsation. As one of the major vibration sources of a vehicle, engine torque is periodic in the crankshaft rotational angle but aperiodic in time as the engine speed changes in real-time. This paper first presents a powertrain vibration analysis based on the transient engine torque input and the conventional TCC slip control. Simulation results show that the conventional time-based TCC slip control does not settle the periodic nature of the engine torque vibration with respect to crankshaft angle. However, a time-varying angle-based control method can solve this issue. The paper then proposes an optimal TCC torque trajectory by using dynamic programming for this time-varying angle-based control method. Simulation results demonstrate the energy saving potential of the optimal trajectory over the conventional method.

Variable Interval Sampling Based Time Varying Tracking Control With Application to Camless Engine

2014 ◽  
Author(s):  
Meng Yang ◽  
Zongxuan Sun
Keyword(s):  
Tracking Control ◽  
Variable Interval ◽  
Sampling Interval ◽  
Tracking Performance ◽  
Time Varying ◽  
Rotational Angle ◽  
Actuation System ◽  
Sampling Points ◽  
Camless Engine ◽  
Interval Sampling

This paper investigates the variable interval sampling based time-varying tracking control in the rotational angle domain. It is found that more sampling points per revolution provide better tracking performance but increase the computational burden. To solve the problem, a varying interval sampling approach is presented to optimize the angular sampling interval for the reference profile, while maintaining the same total number of sampling points. The tracking performance is improved by considering the tracking errors between the sampling points in selecting the optimal sampling intervals. Experimental results from a time-varying internal model based camless engine valve actuation system demonstrate the effectiveness of the proposed method. A quantitative analysis helps to highlight the strength of the variable interval sampling on less computational complexity and better tracking performance.

A New Valve Lift Control Technique in Electrohydraulic Variable Valve Actuation Systems

2010 ◽  
Author(s):  
Mohammad Pournazeri ◽  
Amir Khajepour ◽  
Amir Fazeli
Keyword(s):  
Control Valve ◽  
Operating Conditions ◽  
Valve Lift ◽  
Control Technique ◽  
Variable Valve Actuation ◽  
Actuation System ◽  
Lift Control ◽  
Variable Valve ◽  
Actuation Systems ◽  
Valve Actuation

Besides valve timings and opening duration control, several benefits could be achieved in engine operation if the valve actuation system could control the maximum valve displacement during a particular engine condition. Typically, in most electro-hydraulic variable valve actuation systems (VVA), the maximum valve lift along with valve opening/closing events are adjusted simultaneously by precise control of the spool travel in servo-valves. However, at high engine speeds, concurrent control of timings and peak valve lift becomes difficult and sometimes even impossible due to servo-valve response time limitations. In this paper, a new lift control technique is proposed using a control-valve located in the hydraulic supply line. Using this technique, it is possible to precisely control the valve lift even at high engine speeds. With this mechanism, the control-valve flow area could be adjusted using a low-speed actuator such as an electric motor. In contrast to conventional approaches, where maximum lift is repeatedly controlled within each cycle, valve lift in this technique can be adjusted after few engine cycles, thereby reducing control signal fluctuations and also eliminating the need for ultra-high-speed actuators. The proposed hydraulic VVA system is mathematically modeled, and a non-linear sliding mode controller is designed based on the derived equations. Finally, the performance of the proposed lift control technique is verified under different operating conditions.

Effect of Chemical Hythane Composition on Pressure in Combustion Chamber of Engine

2019 ◽  
pp. 36-42
Author(s):  
A. P. Shaikin ◽  
I. R. Galiev
Keyword(s):  
Natural Gas ◽  
Combustion Chamber ◽  
Power Plants ◽  
Engine Speed ◽  
Combustion Engine ◽  
Fuel Mixture ◽  
Maximum Pressure ◽  
Chamber Volume ◽  
Excess Air ◽  
Scientific Papers

The article analyzes the influence of chemical composition of hythane (a mixture of natural gas with hydrogen) on pressure in an engine combustion chamber. A review of the literature has showed the relevance of using hythane in transport energy industry, and also revealed a number of scientific papers devoted to studying the effect of hythane on environmental and traction-dynamic characteristics of the engine. We have studied a single-cylinder spark-ignited internal combustion engine. In the experiments, the varying factors are: engine speed (600 and 900 min-1), excess air ratio and hydrogen concentration in natural gas which are 29, 47 and 58% (volume).The article shows that at idling engine speed maximum pressure in combustion chamber depends on excess air ratio and proportion hydrogen in the air-fuel mixture – the poorer air-fuel mixture and greater addition of hydrogen is, the more intense pressure increases. The positive effect of hydrogen on pressure is explained by the fact that addition of hydrogen contributes to increase in heat of combustion fuel and rate propagation of the flame. As a result, during combustion, more heat is released, and the fuel itself burns in a smaller volume. Thus, the addition of hydrogen can ensure stable combustion of a lean air-fuel mixture without loss of engine power. Moreover, the article shows that, despite the change in engine speed, addition of hydrogen, excess air ratio, type of fuel (natural gas and gasoline), there is a power-law dependence of the maximum pressure in engine cylinder on combustion chamber volume. Processing and analysis of the results of the foreign and domestic researchers have showed that patterns we discovered are applicable to engines of different designs, operating at different speeds and using different hydrocarbon fuels. The results research presented allow us to reduce the time and material costs when creating new power plants using hythane and meeting modern requirements for power, economy and toxicity.

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