NOVEL DESIGN AND MODELING OF

SHUTTER VALVES FOR CAMLESS

ENGINES

Muhammad Arsalan Jalees Abro

Master’s Student, Department of Mechatronics Engineering, Institute of

Information Technology. Jamshoro (Pakistan)

E–mail: arsalan_jalees@hotmail.com

Saifullah Samo

Department of Mechanical Engineering, Mehran UET. Jamshoro (Pakistan)

E–mail: saifullah.samo@faculty.muet.edu.pk

Dur Muhammad Pathan

Department of Mechanical Engineering, Mehran UET. Jamshoro (Pakistan)

E–mail: dur.pathan@faculty.muet.edu.pk

Irfan Ahmed Halepoto

Department of Electronic Engineering, Mehran UET. Jamshoro (Pakistan)

E–mail: irfan.halepoto@gmail.com

Recepción: 05/03/2019 Aceptación: 27/03/2019 Publicación: 17/05/2019

Citación sugerida:

Abro, M. A. J., Samo, S., Pathan, D. M. y Halepoto, I. A. (2019). Novel Design and

Modeling of Shutter Valves for Camless Engines. 3C Tecnología. Glosas de innovación

aplicadas a la pyme. Edición Especial, Mayo 2019, pp. 518–533. doi: http://dx.doi.

org/10.17993/3ctecno.2019.specialissue2.518–533

Suggested citation:

Abro, M. A. J., Samo, S., Pathan, D. M. & Halepoto, I. A. (2019). Novel Design and

Modeling of Shutter Valves for Camless Engines. 3C Tecnología. Glosas de innovación

aplicadas a la pyme. Special Issue, May 2019, pp. 518–533. doi: http://dx.doi.

org/10.17993/3ctecno.2019.specialissue2.518–533

3C Tecnología. Glosas de innovación aplicadas a la pyme. ISSN: 2254–4143

520

ABSTRACT

For the intake of air fuel mixture and exhaust of gases camshaft operated valves

are mounted on the cylinder head. In this paper, we have proposed a novel

physical model of a shutter valve to replace the traditional camshaft operated

valve resulting in a camless four–stroke engine. The lift control for the opening

and closing of the intake and exhaust valves are monitored traditionally by a

camshaft which is a mechanical component having a xed shape. A camless

engine replaces the camshaft by allowing the control of valves through the

Electronic Control Unit (ECU). The already developed valves have limitations in

terms of lift, life expectancy or higher costs. This research work proposes a novel

shutter valve design instead of a poppet valve for intake and exhaust of four–

stroke engines. These valves are then operated directly by an ECU and controlled

through pulse width modulation. The proposed variation in shutter valve design

optimally adjusts and controls the fuel intake amount and the ow of exhaust

gases in and out of the cylinder respectively. The opening of the valve can be set

to maximum or at the desired angle so that the engine can run according to the

driver’s requirement. The novel design of the shutter valve will reduce the engine

cost and will improve the fuel economy. At the same time, providing complete

control to the driver’s performance preferences.

KEYWORDS

Camless engine, Camshaft engine, Four–stroke engine, Shutter valve, Poppet

valve.

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1. INTRODUCTION

The basic concept of an engine is to convert one form of energy into mechanical

energy and use that energy to do work. There are dierent types of engines

available but in this work, the focus will be given to four–stroke engines and their

performance factors. Since the invention of engines, society has upgraded a lot

of its norms. These engines are used in various types of transport models like

aircraft, ships, trains and road vehicles. For each of these types, the engine is

modied accordingly. Dierent vehicles are suitable for dierent ranges of torque

to be produced. The engine is built according to the environment where it is to be

used. Either a large load is to be carried along which requires heavy torque based

engines or quick mode of transportation is the key focus. In the latter case, high

speed producing engines are required such as in racecars. There are cases where

engines with both power and speed play a vital role. The vehicles have become

the most important part of our socio–economical activities which either run on

petrol, diesel or other forms of non–renewable fuels. The increasing number of

vehicles on road is stressing the non–renewable fuel resources as there hasn’t been

any major discovery since last two decades and reserves are depleting quickly.

On the other side, burning the fuels produce pollutants which are destroying the

environment. To overcome these issues, the researchers are working on dierent

alternatives to power up the engines by making internal and external design

changes for economical purposes and reducing carbon emission at the same time.

The already developed valves have limitations in terms of lift, life expectancy or

higher costs. This research work proposes a novel shutter valve design instead

of a poppet valve for intake and exhaust of four–stroke engines. These valves

are then operated directly by an ECU and controlled through pulse width

modulation. In this paper, we are proposing the design variations in shutter valve

to optimally adjust and control the fuel intake amount and the ow of exhaust

gases in and out of the cylinder respectively. The opening of the valve can be set

to maximum or at the desired angle so that the engine can run according to the

driver’s requirement.

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The valid scope of this research is to replace the traditionally used camshaft

based poppet valves with a suitable model of a shutter valve which eliminates

the requirement of a cam. The intention of the model designed is to increase the

overall economy of the engines and to reduce the rate of production of exhaust

gases by controlling the amount of fuel to be burnt.

The remainder of the paper is organized as under; in Section 2 a technical

comparison between the cam and camless engine is made. The working of IC

engine is discussed thoroughly. In response to existing poppet valve, the novel

prospect of shutter valve is discussed in Section 3. In Section 4, a novel model of

shutter valve for camless engines is proposed, designed and modelled. Section 5

concludes the paper and highlights future research potential.

2. CAM VS CAMLESS ENGINES

According to Heywood (1988), the working of an internal combustion engine

requires a proper balance of air and fuel intake and with that, proper timings are

required to allow the mixture to ow in the engine and the waste gases to ow

out of the engine. The general structure of the IC engine is shown in Figure 1.

According to Roan (1959), in this era, most of the vehicles are equipped with a

mechanical overhead camshaft. According to Siewert (1971), the idea of varying

the valve timing in a spark ignition engine for improved performance, better fuel

economy, improved power, improved turbocharging, ecient emission control

and other performance factors are under consideration since last century. The

most basic type of internal combustion (IC) engines is four stroke engines. The

piston covers four stages called strokes to cover a complete cycle. The movement

of the piston from TDC (top dead center) to BDC (bottom dead center) or vice

versa is called a stroke. These stokes are named as intake, compression, power

and exhaust respectively.

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Figure 1. General structure of the IC engine.

In this paper, we have concentrated on the intake and exhaust stroke. In an IC

engine, the intake of the fuel mixture and the exhaust of the dierent gases from

the cylinder are controlled by the intake and exhaust valves respectively. The

cylinder head has an intake opening and an exhaust opening so that the ow of

the uids can enter or leave the cylinder that is before and after the combustion

process for a required cycle. In a particular cycle, both valves operate only once.

As the cycle begins, the intake valve opens up that is in the rst stroke and at the

end of the cycle, at the last stoke, the exhaust valve opens up in order to release

the exhaust gases.

Traditionally, the types of valves used are the poppet valves. These valves are

operated by a camshaft which is a mechanical component having a xed shape

of lobes. The cam operates the pushrod or lifter which operates the rocker arm

in order to control the opening and the closing of the valves as shown in Figure

2. One of the drawbacks of a cam is that the timing of the valves remains xed

for a predetermined driving functionality. The duration of the opening and the

closing of the intake and exhaust valves are constant and depend on the shape

of the camshaft lobe. At increased revolutions per minute (RPM), the engine

requires a higher amount of air–fuel mixture to pass through the intake valve.

Due to the xed period of time for the opening of the intake valves, the air–fuel

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mixture can blow out of the cylinder and return to the intake manifold thus

creating a state of blowback.

Though a mechanism known as variable valve timing does change the timing

according to the ignition requirements in an Engine Control Unit (ECU) based

engines that is again for limited performance ranges. In a camless engine, the cam,

pushrod/lifter and rocker arm are removed. These alterations not only reduce

the size and the weight of the engine but also oer exible synchronization of

valve operation at particular RPM. The valves in a camless engine are directly

controlled by the ECU which eliminates the need for a timing belt to synchronize

the opening and the closing of the valves with the strokes of the pistons.

Figure 2. Operation of a Poppet value through a cam.

The concept of the camless engine valvetrain system has been revolving since

over the last decade. Though the potential has not yet met the high–performance

criteria. According to Postrioti, Battistoni, Foschini and Flora (2009) as compared

to conventional RPM ranges, the range was limited to much lower RPM values.

The valves in a camless engine are controlled electronically through the signals

from the ECU and a required control circuit according to the valve’s design. These

values can be remapped by mapping the ECU or by altering the programming

of the control circuit. A camless engine thus becomes more suitable and ecient

as compared to the camshaft based engine. It also becomes more economical due

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to the reduction in the size and weight of the engine. With the reduction in size,

as the engine bay is reduced in height, the overall dynamics of the vehicle can be

improved which results in faster accelerations. Other than this, the added cost of

the mechanical components is reduced which improves the manufacturing cost.

3. SHUTTER VALVES VS POPPET VALVES

Current research in the eld of camless engines is focused upon poppet valves.

They have controlled either through electro–hydraulic (Nam, Cho, Park, & Choi,

2017), electro–pneumatic or electro–magnetic circuits (Chen, Chang & Fan,

2019). The authors Tai, Stubbs and Tsao (2001) have developed electromagnetic

valves by using grey box approach through which system identication and

mathematical modelling was performed. The study states experimental results

for the quiet seating issue of the valves. They further recorded the error and

timing of the valves through feedback. As an extension of Tai, et al., (2001),

the authors Gillella and Sun (2011) have developed an improved version of a

camless–valve actuation system which included an internal feedback system to

monitor the working and the timings of the valves.

Current work has been carried out on camless engines using solenoid valves

(Liu & Chang, 2011) but still, there is a dire need to further work on the lifting

and the proper closing of the valves (Anderson, Tsao & Levin 1998). The other

replacement of the mechanical camshaft available in the literature is the electro–

hydraulic valve system (Sun & Kuo, 2010). This system has limits in terms of

practical implementation at low RPM. According to Haas (2010), an electro–

hydraulic valve system (EHVS) based control system was developed which utilizes

the xed volume of oil for the lift of the valves which limits the maximum valve

lift as compared to the cam prole. The intended research controls the valves

through electromagnetic circuit. The poppet valves have their limitations in terms

of use. They have limited lift which matters especially at higher RPMs. The lift

is an essential factor while considering the eciency and the power output of

an engine. Due to limited lift, at higher RPMs, the required fuel mixture does

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not reach the cylinder thus resulting in low engine performance. In the designed

shutter valve, the lift factor isn’t involved. Instead of the lift factor, the shutter

valves open radially which can be adjusted using a dierent number of blades in

a shutter valve. Another factor such as the heavy springs used in the poppet valves

in order to keep the valves properly closed at high pressures, produce a delay in

the lift’s response time and also results in a higher resistance when it comes to

operating them at the precise moment. This process is detailed in Figure 3.

Figure 3. Components of Poppet valves.

Poppet valves in a cam based engine can easily be operated as the driving force is

a heavy mechanical component but when it comes to an electronically controlled

engine, these can only be when provided with a high–power supply. The shutter

valves operate on a simple mechanism which eliminates the use of heavy springs

thus clearing the error of a delay factor and the loss of power from the crankshaft

which results in an ecient system of control. When using the poppet valves, the

pistons are aected by cavities which form over time as the engine is used. The

cavity thus results in a dimpled interior within the combustion chamber. Due to

these cavities, uneven ame propagation takes place. As the cavities increase in

depth, some air–fuel mixture is left unburnt leaving the car run rich and results in

uneconomic fuel combustion. This also results in the loss of energy which results

in the lower performance of the engine.

In the proposed shutter valve, cavities will not be formed due to the mode of

operation and the shape of the shutter valve. This will eliminate the drawbacks

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of loss of energy, engine running rich and out of order. Other than these factors,

poppet valves take up more space in an engine bay and increase the weight

of the engine as compared to shutter valves. Both of these factors reduce the

eciency of the engine. By further reducing the size of the engine, the vehicle’s

aerodynamics can be enhanced which results in an increase in the performance

of the vehicle. The eciency is also increased by the reduction in weight due

to the poppet valves and the required components to operate them. This will

slightly reduce the production cost of the engine. The electromagnetic valves

based camless engines were modelled but were limited in terms of lifting and the

proper closing of the valves (Lino, et al., 2016). Though improvements have been

made since the introduction of this method still there is a lot of work required

to reach the optimum results. An engine based on electro–pneumatic valves was

designed and nowadays it is in use for testing purpose. As per observations of

various researchers, the valves are expensive and there are lots of chances of

uid leakage at higher RPM but these observations need proper verication and

experimental setups to validate.

The purpose of this research is to propose a novel approach towards the camless

engines. For this purpose, the diaphragm shutters are used as shutter valves.

These shutter valves will reduce the loses carried out by the previous systems,

by reducing the use of noisy components and the risk of wear and expensive

maintenance. The implemented model of shutter valves will allow the separate

monitoring and easy tuning which eliminates the hectic process of altering the

camshaft of an engine.

4. THE PROPOSED NOVEL DESIGN OF SHUTTER VALVE

Figure 4 is the novel proposed design of shutter valve’s front view. The valve

consists of two circular disks, 6 blades in between which interlock with each other,

and a slider to operate the blades.

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Figure 4. The proposed novel design of shutter valve.

The interlocking mechanism is present so that the blades may not get bent out

of shape when aected by heavy pressures. At the instance of combustion, the

pressure in the cylinder rises. In the shutter valve, as compared to the poppet

valve, the spring is not required for the linear operation of the valve. The pressure

developed during the power stroke, it is necessary for the intake valves to remain

closed as well as during the compression and the exhaust stroke. On the other

hand, the exhaust valves sustain high pressures during the compression and the

power stoke. So, this shape of the shutter valves keeps the blades in xed shape

and remains tightly closed. This is shown in Figure 5.

Figure 5. Interlocking blades of shutter valve.

In a normal state, when the engine is powered o, the valves remain closed. The

bar on the shutter valve assists the opening and closing of the valve. The ECU

monitors the position of each of the pistons separately by using the crankcase

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sensor which regulates the voltage signal and is transmitted to the control circuit.

When the control circuit signal is activated due to dened pulse timing, the

magnetic contact becomes energized and attracts the rod towards itself as shown

in Figure 6.

Figure 6. Opening of shutter valve during the high state of the control circuit.

When the contact is closed, the operating bar rotates the slider. As the slider

rotates, the blades rotate allowing them to open up or close. This operation

is carried out separately for allowing either the air–fuel mixture to enter the

cylinder or the exhaust gases to leave the cylinder. For both the intake and the

exhaust operations, dierent conguration of the control circuit is required in

order to adjust the operating cycle of the shutter valves. The shutter valves are

enclosed within the casing structure through which the blades cooling mechanism

is achieved. At high temperatures, the blades will get deformed and to avoid that

both the material and the cooling of the blades is essential.

Another feature of these shutter valves is that the performance output is adjustable.

Depending on the drive requirements, the opening and closing diameter of the

shutter valves can be adjusted. There are dierent levels upon which the operating

contact of the control circuit is tuned. Potentially there can be dierent positions

of operating contact ranging from nearest to farthest. Fixing the contact at the

farthest end will result in the complete opening of the valve and adjusting it to the

nearest operating end will result in a narrow opening of the intake shutter valve.

The unburnt fuel will return in the tank to be utilized in the next cycle. Through

the change in the opening, the working of the engine will either produce an

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economic run or a power drive. On the operating bar of the shutter valves, a

spring is mounted as shown in Figure 7.

Figure 7. Cross–sectional view of shutter valve during blades opening.

The functionality of the spring is to keep the valves closed at all times and assist

in the closing of the valve once the control circuit switches from on state to an

o state. Normally when a magnetic circuit switches to the o state, there is a

delay time due to the demagnetizing factor of the attracting metals. The purpose

of this spring is to reduce the delay time and allow fast and easy switching of

the shutter valves. This proposed design alteration of shutter valves will save the

vehicles fuel consumption, resulting in a more economical model. This economy

lends a hand in reducing the nitrogen oxide emissions (NOx).

5. CONCLUSION

Camless engines are emerging research area and its true potential is yet to be

explored in the eld of automobiles. In this paper, the existing camless engines

are thoroughly studied. On the detailed study, a novel model of shutter valve for

camless engines is proposed, designed and modeled for fuel eciency, light weight,

cost eciency, variable valve control, aerodynamics and environmental friendly by

reducing NOx emission. The proposed shutter valve is easy and maintainable and

allows the industries to adapt without any hectic processes or heavy upgrades.

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The modeled design of shutter valve based camless engines will revolutionize

the automobile industry by opening the gates of the novel concept of hybrid

economical sports cars. This can be a new venture for automobile industries to

explore, invest and produce a high grossing production line of futuristic vehicles.

ACKNOWLEDGEMENTS

Authors are highly grateful to Mehran University of Engineering and Technology,

Jamshoro, Pakistan, for the support, the necessary laboratory facilities and

comfortable research environment. The rst author is highly in debt of Engr.

Muhammad Sharif Jamali for his support and guidance in understanding the

designing tools. Special thanks to Amjad Hussain, owner of Hi–Tech Motors

Hyderabad, Pakistan for sharing his technical automobile knowledge.

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