CAMLESS ENGINE

Created by ROYAL MADAN & VIVEK KUMAR

Asst. prof. at Mechanical dept

royalmadan6293@gmail.com

INDEX

1. INTRODUCTION

2. FUNCTION OF CAM

3. EXISTING TECHNOLOGY

4. CAMLESS VALVE TRAIN OPERATION

5. ELECTRO/MECHANICAL

6. ELECTRO /HYDRAULIC

7. BENEFITS

8. CONCLUSION

9. REFERENCES

INTRODUCTIONVarious engine systems have been developed in the effort to improve the engine performance and fuel economy of an automobile.The engine will either have powerful performance or increased fuel economy, but with the existing technology it is difficult to achieve both simultaneously. The conceptual development, design, manufacture, and analysis of a piezoelectric controlled hydraulic actuator. This actuator was developed for use as a replacement for the camshaft in an internal combustion engine, its development results in a new device; called, the camless engine (CLE).

CAMA cam is a mechanical member

that impart desired motions.

Single Cam and Valve

FUNCTION OF CAMSHAFTAs the camshaft rotates, cam lobes,

attached to the camshaft, interface with the engine’s valves.

This interface may take place via a mechanical linkage, but the result is, as the cam rotates it forces the valve open.

The spring return closes the valve when the cam is no longer supplying the opening force.

CAM VALVE TRAIN1.The valve train in a typical internal combustion

engine comprises several moving components that are

cam, camshaft, cam lobes ,poppet valves ,with valve

springs.

2.The camshaft is attached to the crankshaft of IC

engine and rotates relatively to rotation of crankshaft.

3.This dependence on the rotational velocity of the

crankshaft provides the primary limitation on the use of

cam.

4.Since the timing of engine dependent on the shape of

the cam lobes and rotational velocity of camshaft

5.This resulting design represent s a compromise

between fuel efficiency and engine power.

6.Considering this compromise ,automobile

manufacturers have been attempting to provide vehicles

capable of cylinder deactivation ,by variable valve timing

(VVT). 7. Camless VVT allows an engine to experience maximum engine performance and fuel efficiency at each and every engine speed

WHAT IS CAMLESS ENGINE A camless engine uses

electromagnetic, hydraulic, or pneumatic actuator to open the poppet 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.

Camless VVT Models

EXPLANATIONThey are Composed of two

superimposed electromagnets, between which moves a metal part that is interdependent with a push rod.

Electromechanical actuators are placed at the tail-end of the valves.

Management unit send command to the electromagnets which alternatively attract the moving component i.e. push rod.

CONT.Once the solenoid get actuated,

the rocker arm pivots and compresses the valve and valve spring which in turn releases the flow of air in to the engine cylinder.

BLOCK DIAGRAM

SEQUENCE OF OPERATION :

SENSORSELECTRONIC

CONTROL UNIT

ACTUATORS

EXISTING TECHNOLOGYIn response to the needs of improved engines, some

manufacturers have designed mechanical devices to

achieve some variable valve timing. These devices are

essentially camshafts with multiple cam lobes or engines

with multiple camshafts. For example, the Honda VTEC

uses three lobes, low, mid, and high to create a broader

power band. This does represent an increased level of

sophistication, but still limits the engine timing to a few

discrete changes.

Honda VTEC Schematic

The types of camless variable valve actuating systems

being developed can be classed in two groups:

1. Electromechanical

2. Electrohydraulic

Camless Valve train Operation

ELECTROMECHANICAL1. Electromechanical actuators, commanded by a

distribution management unit, control the movement of the valves. There is therefore no longer any direct mechanical bond between the valves and the crankshaft.

2. Camless valve variable timing is electronically operated by a microcontroller which will control electro-mechanical rotary solenoid actuators.

3. The required amount of force and speed needed from a solenoid in order for this system to be effective, rotary solenoids meet the requirement for this system.

4. Each of these solenoids will be connected to the intake and exhaust valves relieving the engine of the load of a cam system.

Camless VVT Models

5.Depending on the load and engine speed, the microcontroller will process the information given and use pulse width modulation (PWM) to actuate the solenoid valves.6.These PWMs will generate square waves that are identical to the timing profile for the most efficient engine at that particular speed and load combination. 7.These PWMs will be sent to the solenoids to actuate the timing of these devices. Once the solenoid is actuated, the rocker arm pivots and compresses the valve and valve spring which in turn releases the flow of air into the engine’s cylinder. 8. Theses generated PWMs are predetermined square waves that will be hard coded and referenced by the microcontroller depending on the load and speed of the engine for maximum engine efficiency.

Advantages of camless VVT versus the Honda VTEC.

Shown above is a screenshot of the program used to simulate the engine performance of an Acura Integra 1.8L with timing profiles that were tailored for each engine speed from 1000 rpm to 5500 rpm in 500 rpm increments.

Below displaying the timing profiles of exhaust and intake valves at 1000 rpm, 2500 rpm and 5500 rpm. Neglecting the other 500 rpm increments between 1000 and 5500 rpm

@ 5500rpm

@ 2500rpm

@ 1000rpm

Exhaust

Intake

these plots were organized in this manner in order to illustrate how the timing profiles change as the engine speed increases.

From the observed data, the brake torque of the crankshaft was plotted against the volumetric flow rate of consumed fuel within the each system.

Overall, the camless VVT system produces more crankshaft torque while consuming the same amount of fuel for each engine speed.

1.By use of this design, the flow of air through the engine’s cylinder can be directly controlled by microprocessor to supply the engine with precise amounts of air at designated engine speeds.2.As a result, the valve lift and timing events of the valve train were experimentally balanced to gain the largest amount of engine performance while limiting fuel consumption.3.The results show that this design would improve the fuel economy of an engine by 2.3% overall compared with the Honda VTEC, ranging from a high 6.5% at engine idle to a low 0.3% at mid range speeds.

Advantage of Electromechanical

ELECTOHYDRAULICIn general terms, electrohydraulic valves comprise poppet valves moveable between a first and second position. Used in a source of pressurised hydraulic fluid and a hydraulic actuator coupled to the poppet valve. The motion between a first and second position is responsive to the flow of the pressurised hydraulic fluid. An electrically operated hydraulic valve controls the flow of the pressurised hydraulic fluid to the hydraulic actuator. In one design, the provision is made for a three-way electrically operated valve to control the flow of the pressurised hydraulic fluid to the actuator. This supplies pressure when electrically pulsed open, and dumps actuator oil to the engine oil sump when the valve is electrically pulsed to close. The use of engine oil as the hydraulic fluid simplifies and lowers the cost of the design by removing the need for a separate hydraulic system.

As is the trend with all modern engine systems, the camless

engine has an even greater reliance on sensors.

The valve actuation and control system typically needs a

manifold pressure sensor, a manifold temperature sensor, a

mass flow sensor, a coolant temperature sensor, a throttle

position sensor, an exhaust gas sensor, a high resolution

engine position encoder, a valve/ignition timing decoder

controller, injection driver electronics, valve coil driver

electronics, ignition coil driver electronics, air idle speed

control driver electronics and power down control

electronics.

BENEFITS OF CAMLESSMore torque is made available.Optimal volumetric efficiency.Increase engine performance.Decrease fuel consumption.Decrease harmful emissionCylinder deactivationIncreasing durability and engine

life

The improvement in the speed of operation valve actuation and control system can be readily appreciated with reference to Figure

It shows a comparison between valve speeds of a mechanical camshaft engine and the camless engine valve actuation. The length of the valve stroke in inches versus degrees of rotation of a mechanical camshaft is illustrated.

APPLICATIONSIn automobile & heavy vehiclesReverse operation is

advantageous in marine equipment having dual outdrives or T-drives.

CONCLUSIONCamless engine provide a great development, in IC engine and mark beginning of 2nd generation engine. However, the future is not necessarily rosy. There are many problems to be overcome with the electronically controlled valves. The problems lie not only in the software required but also the mechanisms of the actuators. Coil transient response times and saturation effects at high rpm are just some of the issues.

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