FUTURE VALVE SYSTEMS IN ENGINES

PRESENTED BY

AAKASH RAJEEVANS7 MECHANICALROLL NO:1

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INTRODUCTION

CAM

•Control the valves of an IC engine•Cams push open valves at proper time & guide their closure•High power consumption•High sound & Vibration•They are inflexible except VTEC & VVT•Could not vary timing, lift & duration of valve opening

VALVE MECHANISM IN CONVENTIONAL ENGINE

• CAM SHAFT

• CAM FOLLOWER

• PUSH ROD

• ROCKER ARM

• VALVE SPRING

• VALVE GUIDE

• VALVE STEM

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WHAT IS CAMLESS ENGINE

• Which eliminates camshaft & mechanical linkage

• It uses electromagnetic or hydraulic to open the valves.

• Actuator can be used to both open and close the valve or an actuator opens while spring closes it.

• Ability to achieve truly variable valve timing in each

cycle.

• It can make engines clean, efficient & responsive

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OVERVIEW OF CAMLESS ENGINE

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ELECTRONIC CONTROL UNIT

VALVE ACTUATORS

SENSORS

MAIN SENSORS

•ENGINE LOAD SENSOR•ENGINE SPEED SENSOR•EXHAUST GAS SENSOR•VALVE POSITION SENSOR•AUXILARY SENSORS

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ELECTRONIC CONTROL UNIT(ECU)

•ECU contains microprocessors with associated software•Sensors sense parameters & send signals to ECU•This ECU controls the actuators to work according to requirements

VALVE ACTUATORS

2 Types of valve actuators are mainly used

•ELECTRO-MECHANICAL SYSTEM•ELECTRO-HYDRAULIC SYSTEM

ELECRO MECHANICAL SYSTEM

• These actuators are use electro magnetic effect

• Components used into these systems are coil , armature , solenoid…

There are 2 types of actuators

1. Double solenoid actuator 2. Moving coil actuator

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DOUBLE SOLENOID ACTUATOR

ELECTRONIC CONTROL UNIT

ENGINE SPEED SENSOR

EXHAUST GAS SENSOR

ENGINE LOAD SENSOR

VALVE POSITION SENSOR

•Sensor sense the parameters and send it to the ECU•ECU analyze the data and send an electric current to the solenoid•In the case of opening send current to solenoid 2 &for closing to the solenoid 1 •Send a feed back from solenoid to ECU

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DISADVANTAGE OF DOUBLE SOLENOID ACTUATOR

•It require high current for its operation•High energy consumption•Non linear behavior•High seating velocity•Require proper seating of valves•Wearing in valves•system cannot vary the amount of valve lift.

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MOOVING COIL ACTUATOR

•Air gap b/w coil &magnet are remain constant•A force produce on coil when it get energized•Variable valve lifting & timing can be possible by adjusting the current in coil•Almost linear behavior•Single coil & controlling is simple•Magnetic force is depends only in current not in position of coil•High precision position control•Seating of valve is an easy task

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Performance of cam-less VVT V/S Honda VTEC

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ELECTRO HYDRAULIC SYSTEM

• Electro hydraulic system uses the elastic property of fluids• A source of pressurized hydraulic fluid and a hydraulic

actuator coupled to the poppet valve.• In one design, the provision is made for solenoid valve to

control the flow of the fluid to the actuator.• Solenoid valves are controlled by ECU• provides continuously variable control of engine valve timing,

lift, and velocity

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Fig1: Layout of hydraulic system

Fig2: Cross section of cylinder head

WORKING OF HYDRAULIC VALVE

•Working based on hydraulic pendulum•During acceleration of valve PE of fluid is converted into KE of valve•During the deceleration KE of valve is converted into PE of fluid in both opening & closing•Minimize energy consumption•HP solenoid valve open the engine valve& LP close•Opening & closing of solenoid valve by ECU

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•Offers continuously variable & independent control of valve motion -lift, operation duration, event of opening•ECV system can control valve velocity, valve acceleration and deceleration•Better fuel economy- 7 to 10 % increase•Higher torque & power- 10 to 15 % increase•Lower exhaust emissions- reduces NO x emissions•Reduction in size & weight

DISADVANTAGE

•System is more complex•Maintenance is difficult•Cost of the system is high

ADVANTAGE OF CAMLESS ENGINE OVER CAMSHAFT ENGINE

CONCLUSION

Even though some disadvantages arepresent, we can expect electro-hydraulic &electromechanical valves to replace theconventional camshaft technology.

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REFERENCE

[1] Michael M.Schechter and Michael B.Levin “Camless Engine” SAE paper 960581.

[2] P. Kreuter, P. Heuser, and IvI. Schebitz, “Strategies to Improve Sl-Engine performance by Means of variable Intake Lift, Timing and Duration”, SAE paper g2044g.

[3] K.Hatano, k. Lida, H. Higashi, and S. Murata, "Development of a New Multi-Mode Variable Valve Timing Engine”,SAE paper 930878

[4] V. Pieron, Y. Postel, E. Nicot, and D. Durrieu, "Electro-Magnetic Valve

Actuation System: First Steps toward Mass Production," SAE 2008-011360.

[5] Y. Wang, T. Megli, M. Haghgooie, K. S. Peterson, and A. G.

Stefanopoulou, "Modeling and Control of Electromechanical Valve

Actuator," SAE 2002-01-1106.

[6] C. Sugimoto, H. Sakai, A. Umemoto, Y. Shimizu, and H. Ozawa, "Study

on Variable Valve Timing System Using Electromagnetic Mechanism,"

SAE 2004-01-1869.

[7] P. Eyabi and G. Washington, "Nonlinear Modeling of an Electromagnetic

Valve Actuator," SAE 2006-01-0043.

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