DOUBLE ACTING MCE-5 ENGINE

PAPER SUBMITTED BY: R.N.Rambalaji

Saravana Sridar

Pre-final year, mechanical engineering,

Coimbatore Institute of Technology,

Coimbatore.

PAPER CLUSTER : ADVANCED IC ENGINES

DOUBLE ACTING MCE-5 ENGINE R.N.Rambalaji, Saravana Sridar

Pre-final year Mechanical Engineering

Coimbatore Institute of Technology, Coimbatore r.n.rambalaji@gmail.com

saran.theprince@gmail.com

Abstract— In the present case scenario, the development of a new IC

engine with high efficiency, high power, low emission levels,

multi-fuel option with mass production capability is in high

demand. Hybrid vehicles conform to the above said criteria. Unfortunately, refining a technology until it is affordable and

performs well enough for the mass market takes a while, and we

might not have electric cars for a few more years. In the

meantime, we engineers are trying to squeeze more life out of

ICEs.

The double acting MCE-5 engine can produce high power

with high efficiencies. The MCE-5 is an all-in-one engine block

integrating both innovative components that transmit power

from the piston to the crankshaft, and exclusive actuators, which

permit controlling the engine Compression Ratio. . Based on the

combination between a rod-crank mechanism and long-life gears,

the MCE-5 is an all-in-one VCR technology integrating both

power transmission and Compression Ratio control.

Its conservative combustion chamber and its totally conventional

and invariable piston kinematics allow making the most of know-

how related to combustion and performance control.

The MCE-5 provides an individual, continuous and reactive

Compression Ratio control to each cylinder of the engine. Its

wide control range comprised between 7:1 and 20:1, permits

serving all VCR strategies with no limitation.

Thanks to its reasonable production costs and exclusive features,

the MCE-5 could rapidly lead to a new generation of fuel

efficient, powerful and attractive vehicles, while opening the way

to crucial engine design strategies for the future. With double

acting principle integration we get two power strokes for four

strokes rather than a single power stroke in conventional IC

engine

I. INTRODUCTION

It’s been more than two centuries earlier the first working IC

engine was developed. Since then the IC engines have

undergone numerous changes to improve its performance in

terms of power and efficiency.

Both power and efficiency can be improved by using the

piston to compress the charge on both sides of the piston.

Unfortunately our conventional engine does not have the

flexibility to support double acting principle.

With the development of advanced technologies, in the

present scenario, there is every possibility of developing a

double action IC engine. The MCE-5 technology provides a

lot of flexibility that our conventional engine doesn’t and

double acting principle can be easily applied.

II. WORKING PRINCIPLE OF A DOUBLE ACTING ENGINE

The double acting engine works on the principle that both

the sides of the piston are used to compress the charge

alternatively and produce two power strokes in four strokes of

the piston

The principle is explained as below,

A. INITIAL POSITION:

Let the piston be at its Top Dead Centre (TDC).

B. STROKE 1

During the first stroke the piston moves from TDC to BDC

thus producing vacuum and thus makes the charge to fill in

the upper part of the cylinder.

C. STROKE 2

Now during the second stroke, the piston moves from BDC

to TDC, thus compressing the charge in the upper part of the

cylinder. At the same time vacuum is created in the lower part

of the cylinder as the piston moves from BDC to TDC and

now charge enters the lower part of the cylinder i.e. the area

under the piston

D. STROKE 3

Now a spark is provided and the charge in the upper

cylinder burns and pushes the piston downwards (power

stroke), thus simultaneously compressing the charge in the

lower part of the cylinder.

E. STROKE 4:

Now a spark is provided in the lower combustion chamber and

now the piston is pushed above, thus enabling exhaust to take

place simultaneously.

And the process continues thus producing “two power

strokes” for four stokes of the piston.

This double acting principle can be successfully applied to our

conventional engine but with few cons. A conventional double

acting engine model is designed in CATIA and its kinematics

were simulated. The results were that such an assembly

working is completely feasible. The model designed is shown

in the fig below,

III. CHALLENGES MET BY CONVENTIONAL DOUBLE ACTING IC

ENGINES

The three main cons that affected the conventional double

acting IC engines is that

Piston radial stress is very high

At lower speeds of engine combustion in lower part of

cylinder doesn’t takes place

At higher speeds, the design leads to high possibilities

of detonations in the lower part of cylinder.

These disadvantages that will hinder the development of a

conventional double acting IC engine can be debugged by

using Variable Compression Ratio-intelligent MCE-5

technology.

IV. VCR-BRIEF INTRODUCTION

Most of us are probably anxious to get rid of internal

combustion engines (ICE) and move on to electric motors. But

it’s a situation that is highly unlikely to happen in the next 20

years. So one has to find a technology that is high efficient but

at affordable cost and environment friendly.

One promising technique is the use of variable compression

ratios

In an internal combustion engine, the compression ratio tells

you what the ratio is between the biggest and smallest

volumes of the combustion chamber in the cylinder. The

concept of modifying that ratio is very old (around the 1920s),

but very few cars have actually used it.

`

The benefits of having a variable compression ratio are that

you can control much more precisely combustion and adjust

the variable to get the best performance for each situation

(acceleration, cruising, deceleration, etc). It becomes

especially potent - in theory - when combined with other

technologies like turbochargers, direct injection, variable

valve timing and lift, etc., from a green point of view, this

mean you could downsize an engine quite a bit while still

getting enough power and achieving high thermal efficiency.

It might even help with the use of (cellulosic) ethanol (which

has different characteristics from gasoline), or to reduce

emissions by optimizing combustion.

This could bring fuel economy to 6.0 L/100 km while

producing 50 hp more! And also imagine a small car that

doesn't need 200+ hp. A 0.8-liter version (or whatever) could

probably get very good MPG, possibly running on cellulosic

ethanol made from agricultural waste.

Variable Compression Ratio is not a revolution; VCR is only a

major technical evolution, which could rapidly be as

indispensable for SI engines as multiple Direct Injections for

Diesel engines

V. THE MCE-5 TECHNOLOGY

Different VCR prototypes have confirmed the exceptional

potential of VCR strategy, but they also revealed that

designing VCR engines that respond to mass-production

requirements is a tremendous technological challenge.

In this context, next step is to identify and study a design that

fulfils all indispensable features for a mass-produced engine in

terms of functionalities, robustness, reliability and durability

while presenting reasonable production costs.

The engine that popped up fulfilling all these qualities is the

MCE-5 intelligent engine.

MCE-5 technology entirely revolutionizes the current working

concept of our conventional IC engine.

It throws away our conventional four bar mechanism, and

integrates a new mechanism to achieve both friction losses

reduction and implementation of VCR-i techniques.

VI. WORKING PRINCIPLE OF A MCE-5 ENGINE

The conventional four bar mechanism is the main source of

the piston radial stress that hinder the development of double

acting engine. The piston radial stress and piston slap is

completely removed by using a roller guided piston in MCE-5

technology

Here the piston is made to reciprocate in the cylinder by a

roller guide. The reciprocation motion is converted in to an

oscillatory motion of a gear wheel, which is also attached to a

control jack for compression ratio control. The oscillatory

motion of the gear is converted in to rotary motion of crank by

a short connecting rod.

VII. STRATEGY OF MCE-5 TECHNOLOGY

General strategy of the MCE-5 technology:

A)-Reduction of friction and pumping losses:

a) High downsizing;

b) High down speeding.

* enabling the reduction of frictional losses by a factor of

2.2 and pumping losses by 7

B) -Improvement of combustion-expansion effectiveness:

a) All loads optimization of relation between:

-Ignition Advance;

- Compression Ratio;

(CR for a wide range of (7:1 to18:1)

-EGR.

D) -Additional features:

a) Idle speed reduction;

b) Cold starting pollutant emissions reduction;

c) Maximum fuel flexibility (VCR)

MCE-5 technology eliminates the need for compromise

between BMEP and Compression Ratio. Fixed compression

ratio calls for compromise.

High BMEP (to serve downsizing + downspeeding)

penalizes possible max Compression Ratio;

High Compression Ratio (increased expansion

efficiency) penalizes possible max BM

.

MCE-5 technology thus combines the advantage of diesel and

gasoline engines.

VIII. MCE-5 TECHNOLOGY DESCRIPTION

A. – Crankcase:

The MCE-5 multi-cylinder crankcase is developed to

implement all VCR strategies without limitations in order to

derive maximum effectiveness without any associated risks. In

addition, this crankcase maintains all the MCE-5 technology’s

potential to reduce friction losses and to increase the

mechanical resistance and durability of engines, by providing

a more robust structure.

B. – Piston

Unconventional piston kinematics can lead to unexpected

behaviours and defects related to internal aerodynamics and

engine components noise emissions, durability, and

mechanical efficiency. Taking this in to account the guided

piston is an exclusive MCE-5 feature that radically simplifies

piston design with features like; high compression ratio

precision, conventional piston kinematics; low friction losses

and high reliability are the critical features that will eliminate

piston slap and radial stress, which have a direct impact on

friction losses, blow by, noise emissions, wear and oil

consumption

The opportunity to reduce rings’ tension and resulting friction

losses is mainly due to the fact that the MCE-5 roller-guided

piston preserves bore cylindricity, this ensures a well

distributed ring/cylinder pressure and an improved sealing and

oil consumption control during the whole engine life.

C. Roller:

The roller helps to guide the piston in a rack. As a result,

torque on crankshaft no longer results from forces applied to

the cylinder by the piston, but from forces applied to rollers.

D. Gear wheel:

The gear wheel is an asymmetrical component with a complex shape. It comprises 4 high-loaded teeth subject to gas pressure and high inertia forces at Top Dead Centre (TDC), and 4 low-loaded teeth only subject to low inertia forces at BDC. The gear wheel also comprises rolling surfaces, which work together with those of the piston rack and of the control rack. In addition, the opening made inside the gear wheel to house the rod small-end has 2 axial rod-stop surfaces.

Forging is taken as the mass-production technique for these

gears. Depending on instantaneous tangential stress applied to

their teeth, the MCE-5 spur gears present an efficiency that

always remains between 99.2 and 99.7%.

Thanks to their high efficiency, the MCE-5 spur gears

guarantee an advantageous final friction losses balance to the

entire engine block.

E. Control jack:

The control jack maintains a precise compression ratio

control with hydraulic jacks or with a ECU unit.

F. Crank and rod:

The MCE-5 crank and rod offers another potential friction

reduction source, due to the big-overlap and rigid MCE-5

crankshaft (its crank radius is reduced by half).

Indeed, hydrodynamic bearings diameter could be reduced

thanks to improved natural crankshaft rigidity

IX. COMPRESSION RATIO CONTROL TECHNIQUE

In fact, the first factor for the hindrance of the development of

double acting engine is removed by the roller guided piston.

The next two cons of double acting conventional IC engine

can only removed by applying VCR techniques.

In a MCE-5 engine, the compression ratio is controlled by

hydraulic jacks at present. With our current technological

revolution, an ECU unit and sensors can replace the hydraulic

jacks.

A) ECU and its evolution:

Engines are more sophisticated and efficient in 2008 than

they were in the past but less so than they will be in the future.

They are equipped with many sensors that send information to

the engine control unit (ECU) indicating the position of the

accelerator pedal, the intake airflow, and the oxygen content

in the exhaust gases or even the engine speed. The ECU can

thereby respond to the driver’s torque demand, prepare an air-

fuel mixture with the proper proportions or obtain the highest

efficiency from gas expansion. The ECU manages the

operation of the engine via actuators that it controls

electrically. These actuators are, for instance, used to regulate

the opening of the throttle valve, the amount of fuel injected,

the valve timing or the ignition timing. The ECU has “tables”

that indicate the adjustments required for each actuator given

the engine’s operating conditions.

The ECU also has logical functions that allow real-time

calculation of certain values that are not in its tables. All

modern engines today operate according to these principles.

There is, however, an essential parameter over which the ECU

has no control: the compression ratio. Yet, this parameter

directly conditions engine efficiency, pollutant emissions and

the engine’s torque and power performances. Compression

ratio control has so far never been possible for lack of an

appropriate technology. This shortcoming has led to increased

fuel consumption, limited torque and power and less control

over pollutant emissions. The fixed compression ratio

represents a real technological lock on gasoline engines that

MCE-5 is now opening by providing a variable compression

ratio. This new actuator, which allows compression ratio

control, drastically increases the performances and energy

efficiency of gasoline engines.

B) Compression ratio control in double acting engine:

There will be two knock sensor will be continuously

monitoring the pressure and temperature in both the upper and

lower combustion chamber and send signals to the ECU, thus

aiding to achieve the optimal compression ratio. The CR

sensor accurately points the position the control jack, thus

providing precision compression ratio control.

With the aid of the ECU unit it is possible to switch CR

from 7:1 to18:1 in a mere 25-50 ms.

Thus when the engine is at low speeds, the compression

ratio in the lower chamber is made high and thus aiding the

combustion in the lower chamber at low speeds.

When the engine operates at high speeds, the compression

ratio is made less, so that detonation does not occur.

X. POWER AND TORQUE COMPARISON BETWEEN A 4 CYLINDER

DMCE-5 ENGINE AND A V-6

Indicated power IP = (IMEP*A*L*n*100)/60 KW

IP = Indicated power

IMEP = Indicated mean effective pressure

A = Area of the bore

L = Stroke length

n= number of cycles per minute

Let us assume,

Let IMEP be 10 bar, bore diameter be 10cm, stroke length be

12cm

Speed of engine be 3500 rpm

Let the piston bar diameter be one fifth of piston diameter.

Power produced in the

Upper power stroke = {(10)*(π*(5*10^-

2)^2)*(12*10^-2)*3500*100}/60*2

=27.495 kW

~ 37 hp

Power produced in

Lower power stroke = {(10)*(π*(4*10^-2)^2)*(12*10^-

2)*3500*100}/60

=17.9 kW

~ 24 hp

Indicated Power produced by the double acting engine

= 37+24

= 61 hp

Assuming the same values,

Indicated Power produced by conventional

Single cylinder 4s engine = {(10)*(π*(5*10^-

2)^2)*(12*10^-2)*3500*100}/60*2

~ 37 hp

Increase in power produced with double acting principle per

cylinder = 65%

Let the MCE-5 double acting engine be a 4 cylinder,

Hence indicated power produced by a 4 cylinder MCE-5 =

244 hp

Frictional losses will account for 22% of the indicated power,

With our VCR concept MCE-5 technology integration, we

will have frictional losses less than that of the conventional IC

engine. The frictional losses in the MCE-5 engine are around

8-12%. Let us assume it to be 13% with a worst case scenario

For the DMCE-5 IC engine,

Assuming the frictional losses to be 13%,

Friction losses = 31.72 hp

Hence brake power produced by

4 cylinder DMCE-5 = 212.28 hp

For conventional IC engine,

Let the conventional engine be a V-6

Indicated power produced by V-6 =222 hp

Assuming frictional losses to be 22%

Frictional losses = 48.84 hp

Hence brake power produced by V-6 = 173.16 hp

BP produced by 4 cylinder DMCE-5 engine = 212.28 hp

BP produced by 6-cylinder

4s conventional engine = 173.16 hp

We know,

Torque produced = (BP*60000)/ (2*3.1428*N)

Torque produced by a 4 cylinder = 432 Nm

Torque produced by a V-6 = 352 Nm

Increase in torque = 23%

All these results yield a single fact that DMCE-5 can replace

much bigger engines but with comparable power and high

efficiency. Also the given figures will be doubled if a turbo

and direct injection is used with MCE-5 technology.

Thus comparing the performances of DMCE-5 and a V-6 we

find a 4-cyinder DMCE-5 producing more power and torque

than a much bigger conventional V-6.

XI. CONCLUSIONS

Thus there is every possibility of developing such a high

efficient, high power IC engine that is highly reliable and

robust which can be mass produced. Future cars and

automobiles require high efficient green technologies, with a

door opened for multi-fuel usage. This DMCE-5 technology

can provide all best possible solutions to our future cars, at

affordable prices.