Camless Engine Research Articles

A Robust Cascade Sliding Mode Control for a Hybrid Piezo-Hydraulic Actuator in Camless Internal Combustion Engines

This paper deals with a hybrid actuator composed by a piezo and a hydraulic part and with a cascade sliding mode control structure for camless engine motor applications. The idea is to use the advantages of both, the high precision of the piezo and the force of the hydraulic part. In fact, piezoelectric actuators (PEAs) are commonly used for precision positionings, despite PEAs present nonlinearities, such as hysteresis, saturations, and creep. In the control problem such nonlinearities must be taken into account. In this paper the Preisach dynamic model of the piezo actuator with the above mentioned nonlinearities is considered. The control structure consists of two feedforward controllers and two cascade sliding mode ones. The robustness of the proposed scheme consists of the fact that the sliding control structure is independent of the dynamic model of the controlled system. Simulations with real data are shown.

Development of a camless engine valve actuator system for robust engine valve timing control

In this paper, a camless engine valve actuator (CEVA) system for robust engine valve timing control is presented. A particularly challenging control obstacle, shown in hydraulic actuation system for camless engine valve actuators, is the sluggish response of valve actuators at a cold operating condition. This is mainly due to the characteristics of oil viscosity with respect to temperature changes. At a low temperature condition, CEVA shows the very sluggish response. The retarded valve opening and closing timing, by CEVA’s slow response at low temperature, causes an increase in pollutant emission and cylinder temperature during engine operation. In order to avoid these adverse effects by retarded timing, the new valve timing controller is proposed to control opening timing and closing timing, which is robust against temperature variations. A proposed valve timing controller is for guaranteeing the valve timing repeatability without using expensive position sensors. Experimental results indicate the feasibility of a fully variable valve timing control and CEVA system which can be constructed at a low cost.

The Optimal Strategies for Improving Efficiency in Camless Engines

In this paper, an unthrottled camless engine model, which equipped electromagnetic valvetrain (EMV), has been built for performance simulation of engine dynamics. The combination of the techniques of cylinder deactivation (CDA) and variable valve timing (VVT) has been examined for different engine speeds and engine loads. The results concluded that the mode of two-cylinder deactivation considerably improves the fuel consumption at low engine load. Meanwhile, the one-cylinder deactivation mode is an optimal fuel economy mode for medium engine load. The normal engine mode fairly satisfies the driving torque and fuel economy in a vehicle, and thus it fits the optimal mode for the full loads. Additionally, the results also show that the optimal intake valve closing (IVC) timing for different engine speeds and loads. The IVC timing depends on engine speed linearly while the optimal IVC timing insignificantly changes at different engine loads when CDA is applied. By the determined CDA-VVT strategy, a camless unthrottled engine can maintain high efficiency operation for different speeds and loads.

Verification of Hybrid Automata Diagnosability by Abstraction

A notion of diagnosability for hybrid systems is defined, which generalizes the common notion of observability. We propose an abstraction procedure to translate a hybrid automaton into a timed automaton, in order to verify observability and diagnosability properties. We introduce a procedure to check diagnosability, and show that for the system class of our abstraction (namely for a subclass of timed automata: the durational graphs) the verification problem belongs to the complexity class P. We apply our procedure to an electromagnetic valve system for camless engines.

Design, Modeling, and Control of a Camless Valve Actuation System With Internal Feedback

This paper presents the modeling and control design of a new fully flexible engine valve actuation system, which is an enabler for camless engines. Unlike existing electromechanical or servo-actuated electrohydraulic valve actuation systems, precise valve motion control is achieved using a very stiff hydromechanical internal-feedback mechanism. The entire feedback mechanism is built into the physical design of the system. The external control only activates or deactivates the feedback mechanism in real time using simple two-state valves. This helps reduce the system cost, and thus enables mass production. The trajectory of the closed-loop system is purely dependent on the design parameters of the internal-feedback system. A mathematical model of the system has been developed and validated with experimental results from a prototype system. The “area-schedule” is identified as the most critical design feature, which affects the trajectory of the closed-loop system and, therefore, needs to be designed systematically to optimize the performance of the system as well as improve its robustness. By treating this feature as the feedback-control variable, the design problem is transformed into a nonlinear optimal control problem and solved numerically using dynamic programming. The effectiveness of the proposed design procedure is verified with case studies.

Simultaneous Improvement of Fuel Consumption and Exhaust Emissions on a Multi-Cylinder Camless Engine

Simultaneous Improvement of Fuel Consumption and Exhaust Emissions on a Multi-Cylinder Camless Engine

Simultaneous Improvement of Fuel Consumption and Exhaust Emission by Using Multi-Cylinder Camless Engine

Simultaneous Improvement of Fuel Consumption and Exhaust Emission by Using Multi-Cylinder Camless Engine

816 小型単気筒用カムレスエンジンの開発 : ミラーサイクルエンジンへの適用(OS10-3 エンジンシステム(3),オーガナイズドセッション:10 エンジンシステム)

816 小型単気筒用カムレスエンジンの開発 : ミラーサイクルエンジンへの適用(OS10-3 エンジンシステム(3),オーガナイズドセッション:10 エンジンシステム)

1308 カムレスエンジン用電子油圧動弁アクチュエータの研究(流体アクチュエータ,一般講演)

In recent years, two types of variable valve actuators, electromagnetic and electro-hydraulic, have been developed for cam-less engines. The issue of these actuators is how to attain reliable control of the valve landing-velocity deceleration without any electronic position sensor. With this in mind, the former type of actuator is not so resistant to gas-pressure change, while the latter has issues of power waste and limited speed for quick motion control. The authors developed a sensor-less electro-hydraulic valve actuator (EHVA), with a hydro-mechanical position feedback mechanism in 2002 by using a 2-port switching valve. It operated in 24ms for positioning 12mm in stroke. This paper presents acceleration technology for working at an engine speed of 2100rpm and total valve opening time of 19ms, by applying a 3-port switching valve to the EHVA. The parameters of the EHVA were optimized using the bond graphs simulation program, and it succeeded in completing the valve lift motion within 19ms in a full stroke. Moreover, another type of electro-hydraulic valve-actuator for a four-valve engine succeeds to position the intake valve 11mm in displacement within 35ms and to close it under 0.25m/s in landing velocity.

Electromechanical Valve Actuator with Hybrid MMF for Camless Engine

As one of variable valve timing (VVT) approaches, the electromechanical valve actuator (EMVA) uses solenoid to actuate valve movement independently for the application of internal combustion engine. This paper proposed an EMVA structure by incorporating the hybrid magneto-motive force (MMF) implementation in which the magnetic flux is combined by the coil excitation and permanent magnets. Making use of the dedicated flux arrangement, the proposed device can be used to fulfill the VVT features with reduced power source requirement and less electric device components. A dual flux channels EMVA is detailed and the design procedures are presented. Comparing with the conventional EMV, the proposed prototype shows a lot of advantages such as compactness, high temperature tolerance, fast response, relieve of starting current, and variable current actuating timing.

Non-linear control of electromagnetic valves for camless engines

Conventional internal combustion engines use mechanical camshafts to command the opening and closing phases of the intake and exhaust valves. The lift valve profile is designed in order to reach a good compromise among various requirements of the engine operating conditions. In principle, optimality in every engine condition can be attained by camless valvetrains. In this context, electromagnetic valves appear to be promising, although there are some relevant open problems. In fact, in order to eliminate acoustic noises and avoid damage to the mechanical components, the control specifications require sufficiently low impact velocities between the valve and the constraints (typically the valve seat), so that “soft-landing” is obtained. In this paper, the soft–landing problem is translated into a regulation problem for the lift valve profile, by imposing that the valve position tracks a desired reference, while the modelled disturbances are rejected. Both reference and disturbance are generated by an autonomous system. The submanifold characterized by the zeroing of the tracking error and the rejection of the disturbance, is determined. Finally, the stabilization problem of the system trajectory on such a manifold is solved.

Fuel economy and torque tracking in camless engines through optimization of neural networks

The feed forward controller of a camless internal combustion engine is modeled by inverting a multi-input multi-output feed forward artificial neural network (ANN) model of the engine. The engine outputs, pumping loss and cylinder air charge, are related to the inputs, intake valve lift and closing timing, by the artificial neural network model, which is trained with historical input–output data. The controller selects the intake valve lift and closing timing that will mimimize the pumping loss and achieve engine torque tracking. Lower pumping loss means better fuel economy, whereas engine torque tracking gurantees the driver’s torque demand. The inversion of the ANN is performed with the complex method constrained optimization. How the camless engine inverse controller can be augmented with adaptive techniques to maintain accuracy even when the engine parts degrade is discussed. The simulation results demonstrate the effectiveness of the developed camless engine controller.

３ポート高速電磁弁によるカムレスエンジン用電子油圧可変動弁の高速化

In recent years, two types of variable valve actuators, electromagnetic and electro-hydraulic, have been developed for cam-less engines. The issue of these actuators is how to attain reliable control of the valve landing-velocity deceleration without any electronic position sensor. With this in mind, the former type of actuator is not so resistant to gas-pressure change, while the latter has issues of power waste and limited speed for quick motion control. The authors developed a sensor-less electro-hydraulic valve actuator (EHVA), with a hydro-mechanical position feedback mechanism in 2002 by using a 2-port switching valve. It operated in 24ms for positioning 12mm in stroke. This paper presents acceleration technology for working at an engine speed of 2100rpm and total valve opening time of 19ms, by applying a 3-port switching valve to the EHVA. The parameters of the EHVA were optimized using the bond graphs simulation program, and it succeeded in completing the valve lift motion within 19ms in a full stroke.

DEVELOPMENT OF A SENSOR-LESS ELECTRO-HYDRAULIC VALVE ACTUATOR FOR A CAM-LESS ENGINE

A fully electronically controllable valve-actuator has potentials of improving volumetric efficiency at gas exchange, and of presenting variable compression-ratio. This paper describes a new type of hydro-mechanical position-servo electro-hydraulic valve actuator for a cam-less engine. The piston is positioned hydro mechanical feedback mechanism, which balances the flow rate of the feedback slot to the pilot valve. The feedback-slot opens its area in proportion to the piston displacement. This mechanism succeeds to decelerate the landing-velocity of 0.2m/s at a working speed of 1.0m/s for valve lift of 12mm, and to actuate the valve at a volumetric efficiency of 95% within lag times of opening 18ms and closing 8ms, that is possible to work at an equivalent engine rotational speed of 2100rpm. The actuator is energized by the hydraulic power source of flow-rate of 6.7L/min and pressure of 14MPa.

Development of a piezoelectrically-controlled hydraulic actuator for a camless engine. Part 1: System design

A camless engine proof-of-concept prototype was completed on the basis of the use of piezoelectric control of a hydraulic actuator. This novel approach was taken in an attempt to enhance earlier solenoid-based camless engine prototypes, several of which are reviewed as an introduction to camless engine technology. Following a historical review, an overview of the piezoelectrically- controlled camless engine actuator is discussed. The prototype system is capable of displacing an engine valve up to 12.4 mm, and valve actuation frequencies of up to 500 Hz have been obtained. The proof of concept can be considered successful, as it demonstrates the potential of piezoelectric control of hydraulics for use as an internal combustion engine valve actuator. Furthermore, in conjunction with variable timing, the piezoelectric control based pilot allows for direct regulation of other engine valve parameters including variable lift and seating velocity.

Development of a piezoelectrically-controlled hydraulic actuator for a camless engine. Part 2: System modelling

An analysis of existing models for hydraulic servo valves is presented for use in simulations of a camless engine actuator. Because of the limitations of the accepted models, a new servo valve model is derived, presented and verified. The updated model allows for more complex internal geometry, including new port shapes and port lapping parameters. Comparative results are presented, outlining the significant improvement in valve lift versus time simulation of the newly derived model. The improved model results allow for better simulations and control system design for camless engine valve actuators.

Control of an electro‐mechanical valve actuator for a camless engine

AbstractIn an electro‐mechanical valve actuated engine, the valves are driven by solenoid‐type actuators and cam‐shaft is eliminated. Individual control of each valve provides flexibility in valve timings over all engine conditions and fully exploits the benefits of variable valve timing. This paper pertains to the closed‐loop control of an electro‐mechanical valve actuator. The primary emphasis is on the soft‐seating problem, in which the valve and the moving actuator parts need to be brought to a soft‐stop at the end of their travels. The actuator control features which provide reliable valve motion are discussed in detail. Several illustrative experimental results are also presented. Copyright © 2004 John Wiley & Sons, Ltd.

Iterative learning control for soft landing of electromechanical valve actuator in camless engines

Variable valve timing allows improvements of internal combustion engines and can be achieved by camless actuation technology. In this paper we consider an electromechanical valve (EMV) actuator. One of the main problems in the EMV actuator is the noise and wear associated with high contact velocities during the closing and opening of the valve. The contact velocity of the actuator parts can be reduced by designing a tracking controller that consists of a linear feedback and a nonsquare iterative learning controller (ILC). With the ILC methodology we update the feedforward signal of the feedback controller every cycle based on the error between the actual valve position and the desired position. The methodology is reviewed and both simulation and experimental results are presented. We explore the disturbance rejection capability of the control scheme by simulating conditions with an unknown force acting on the valve similar to the ones present during varying engine load.

Inherent limitations and control design for camless engine idle speed dynamics

AbstractThe idle speed control problem of a spark‐ignited engine equipped with a camless valvetrain is considered. The camless valvetrain allows control of the individual intake and exhaust valves of each cylinder and can be used to achieve unthrottled operation, and consequently, optimize the engine performance. We formulate the speed control problem for this engine and show that it exhibits unstable open‐loop behaviour with a significant delay in the feedback loop. The instability is intrinsic to the unthrottled operation and specific to the camless actuation used to achieve the unthrottled operation. The delay is caused by the discrete combustion process and the sensor/computer/actuator interface. We demonstrate the inherent system limitations associated with the unstable dynamics and the delay and provide insight on the structural (plant) design that can alleviate these limitations. Finally, stabilizing controllers using classical and modern robust design techniques are presented and tested on a nonlinear simulation model. Copyright © 2001 John Wiley & Sons, Ltd.