increasing fuel efficiency of engine

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Serguei
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increasing fuel efficiency of engine

Postby Serguei » Sun Nov 19, 2017 5:23 pm

Improving fuel efficiency of the engine.
The modern scales of the production of the piston engines of the internal combustion have resulted in their significant impact on an environment. The emission from engines of internal combustion essentially increase the concentration of the chemical substances in the air, water, soil and become dangerous to the human life. The problem now has no solution and at the same time is characterized by the steady tendency of the increase.
One of the basic ways to decrease the harmful emission of by-product gases is to improve fuel efficiency of engines. The size of harmful emissions is determined by the perfection of a design of the internal combustion engine.
It is necessary to note, that the huge work on the perfection of the engines now is being done and significant results in the decrease of emissions in an environment are being achieved.
At the same time, the tendency of the increasing impact on an environment remains, and prompts the search for the new solutions of the problem.
The conventional engine of the internal combustion are constructed under the classical circuit, namely, a cylinder, a piston, a rod and a crankshaft. It is necessary to note, that in traditional engines a number of well-known deficiencies takes place, namely:
1. An inefficient combination of the pressure upon the piston and the tangential force on the crankshaft.
Here it is necessary to note two aspects:
а)The process of the combustion of the mixture begins before the piston arrives at the “top dead point” and it means that the movement of the piston to the ”top dead point” is counteracted by the total pressure: the sum of the degree of the compression, and the increasing pressure of the inflamed mixture, and that results in loss of the power.
b) During the maximal increase of the pressure and the combustion of the significant part of the mixture, the crankshaft turns by the angle from 0 ° up to 90 °. Thus the coefficient of the tangential force to the force working on the piston changes from the value of 0 up to the value of 1.
Thus, during the turn of the crankshaft from 0 up to 90 degrees, the combination of two phenomena is observed:
а) The change of the pressure from maximal up to minimal;
b) The change of a coefficient of the tangential force to the force working on the piston from the value of 0 up to the value of 1. 2.The engine of the internal combustion uses in the best case scenario only 75 % of the fuel and 25 % goes in the exhaust pipe and the muffler. Namely, this part of the fuel is burning in the catalyst. But catalyst is the very expensive device and it requires the substantial part of the powerful of the engine for pumping the fuel through a dense net of the surfaces of the catalyst. There are several reasons for this phenomenon and one of them is the very short time of the process of the burning. The average time of the burning of the fuel in the cylinder is 0.001sec. In other words the effectivity of the engine depends on the length of the motion of the piston. But the length of the motion of the piston is directly related with the size of the crankshaft and this relationship limits the length of the motion of the piston.
3. The significant influence on the fuel efficiency makes also a short time for the exhaustion of the burned mixture. It means that the new portion of the fresh air-gas mixture is mixed with remains of the burned mixture. These phenomenon decreases the powerful of the engine.
4. When the piston is at the “top dead point”, the compressed mixture is ignited. It is known that for the full and complete combustion of the fuel vapor desirable the high temperature and the high pressure. But immediately, when the piston passed the “top dead point”, it starts to move down with the significant increasing of the space above the piston. With the spread of the flame front of the mixture in the combustion chamber the first portions of the mixture will burnt at the high temperature and the high pressure. But the latest portion of the hot mixture burns under the condition of the sharply declining of the pressure and the falling of the temperature. For this reason, the part of the mixture does not have the time to burn or not burn fully.
On the video is shown a two-stroke engine.
https://www.youtube.com/watch?v=tVGRqrjPzDw
The engine consists of two pistons (a black main and a red additional), as well as, two valves. The first valve, the intake valve, provides intake of the fresh air-gas mixture into the volume above the additional piston. The second one provides transfer of the compressed fresh air-gas mixture from the volume above the additional piston into the volume above the main piston and separates (closes) volumes above the main and the additional pistons after the ignition of the fuel in the volume above the main piston. There is also a port for the exhaustion. The transfer of the power from the force of the pressure above the main piston to the power shaft is provided by a crémaillère.
There are several differences from the classical engine, namely:
1. In the “top dead points” the piston is motionless while racks run around sprockets. When the piston in the “top dead point” and motionless is created the situation of the possibility for the burning of the mixture in the chamber with the constant volume. It will result to the significant increasing of the pressure and the temperature. The meaning of the pressure and the temperature could be a very high and may result to the destroying of the engine. It means that moment of the time of the ignition of the mixture must be optimized and will allow having the significant optimized pressure and will not allow destroying of the engine. In this case Carnot Cycle will look in a new image.
2. In the “bottom dead point” the piston is motionless, also like in the “top dead point”, while racks run around sprockets. This result to the significant increase of the time for the exhaustion of the burned gas. It means that the inner volume of the cylinder is ready to take the new fresh portion of the air-gas mixture. In the suggested design of the engine two strokes fulfill simultaneously, namely the work stroke (combustion) and the intake stroke. Both strokes are separated. When both (main and additional) pistons move upwards, the fresh air-gas mixture pumped by the additional piston into the volume above the main piston.
3. A distinctive feature of the suggested engine is that the shoulder of tangential force on the power shaft on all way of the moving of the piston remains constant. The change of the magnitude of the torque in this case is defined only by one factor, namely, the change of pressure in the cylinder in the process of the moving of the piston. Statistical meanings of variations of moments in the suggested design and in the design with the crankshaft during the turning of the power shafts from 0 to 180 degrees could be characterized by an average arithmetic values. The average arithmetic value of the moment in the suggested design is 1.83 times greater than the average arithmetic value of the moment in the existing design.
4. Also necessary to note that in the new design of the engine exists possibility significantly increase the length of the motion of the piston that increasing the time for the effective burning of the fuel.
It is natural that both engines must be equipped with flywheels to compensate an uneven rotation.
In conclusion possible to say that suggested engines have a row of advantages that are mentioned above and like classical two-stroke engine it has not a camshaft and valves connected with it. The identified reserves of the capacity allow have the powerful engine with the low number of the revolution that results to decreasing of the thermal intensity, increasing of the reliability and wear resistance and as well as decreasing the fuel consumption and the harmful emission.
Last edited by Serguei on Sun Nov 26, 2017 9:38 am, edited 3 times in total.

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Merlyn
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Re: increasing fuel efficiency of engine

Postby Merlyn » Mon Nov 20, 2017 1:51 am

So it would appear from all the foregoing that PV /T still remains a Constant then.
Remembering The Good Old days, when Chiefs stood watches and all Torque settings were F.T.

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Big Pete
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Re: increasing fuel efficiency of engine

Postby Big Pete » Mon Nov 20, 2017 5:50 am

..and PV to the power 1.4 is also a constant where 1.4 is the adiabatic index for air / Nitrogen. (the ratio of the specific heat capacities at constant volume and constant pressure)
Engines can easily be made with a higher thermal efficiency (Carnot efficiency) by increasing the peak pressure and temperature, however, that requires more expensive heat resistant materials and thicker metal to contain the pressure. However this means the engine is heavier for its power output as well as being more expensive to build and having more "Embodied Energy" in it.
The reason that fuel injection is continued after TDC is to increase the power output without increasing the size, weight, cost, and Embodied Energy of the engine.
Current production designs are optimised between the Capital Cost of the engine and its running costs, except where there has been Political interference which makes the engines more expensive to buy and operate.
BP
It is always better to ask a stupid question than to do a stupid thing.

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Merlyn
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Re: increasing fuel efficiency of engine

Postby Merlyn » Mon Nov 20, 2017 6:35 am

And on a lot of engines with multipoint injections ( some as many as eight before, during , after and in case of injections ) that last squirt is to burn off scale/ slag / carbon buildups to reduce DPF periods.
( although the exhaust uptakes still clag up, dirty job too )
Add blue is sometimes added in a special tank which automatically squirts in the exhaust at timed intervals on a lot of smaller stuff to do the same job.
It's not cheap for what it is and what's the main ingredient .
Distilled water is about 80% of its makeup.
Remembering The Good Old days, when Chiefs stood watches and all Torque settings were F.T.

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Big Pete
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Re: increasing fuel efficiency of engine

Postby Big Pete » Mon Nov 20, 2017 10:22 am

That last 20 per cent, is Urea ammonium nitrate also known as Pig's Piss or Pig's Urine.
It is always better to ask a stupid question than to do a stupid thing.

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Merlyn
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Re: increasing fuel efficiency of engine

Postby Merlyn » Tue Nov 21, 2017 1:41 am

Add Blue tester is off my job list then.
Wonder what's next in this bid to emit fresh air only to atmosphere.
Hybrid seems to be gathering pace plus loads of gas of all descriptions / types / makes / blends etc .
Even human waste powered diesels are being tried over here.
Image being a futuristic plumber on a ship with all toilets plumbed straight into the fuel storage tanks.
Compressed air blockages set ups or in the tank you go.
Well and truly in the sh one t jobby.
Remembering The Good Old days, when Chiefs stood watches and all Torque settings were F.T.

Serguei
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Re: increasing fuel efficiency of engine

Postby Serguei » Tue Nov 21, 2017 8:45 am

Dear friends Mr. Big Pete and Merlyn,
thank you so much for participation in discussion. Please note that in your comments and in my abstract the key word is optimized, namely " moment of time of ignition of mixture must be optimized..... ". In my opinion it is possible to define "gold middle" where will be taken into consideration pressure, temperature, weight and cost of engine etc. And more one note. It seems that you did not have a look at video that mentioned in abstract. If you have time and wish, please have a look.

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Merlyn
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Re: increasing fuel efficiency of engine

Postby Merlyn » Tue Nov 21, 2017 9:54 am

Sergei,
Had a look at your video with interest, different use of a rack I have to say.
Don't know about it flying around at speed though in a crankcase.
Splash lubed?
Struggling to factor into the equation of mechanical efficiency the cost input?
Wondered if that was separate?
Remembering The Good Old days, when Chiefs stood watches and all Torque settings were F.T.

Serguei
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Re: increasing fuel efficiency of engine

Postby Serguei » Tue Nov 21, 2017 2:41 pm

Merlyn,
Thank you for interest.
I think there is not problem. Racks move straight and rotate but crankshaft as well as rotates. Lubrication system has long time history of using and perfection of design of system is without doubt. The Capital Cost of the engine and its running costs I think is in good proportion. As you noted it is two stroke engine which always has a simpler design and less expensive

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Merlyn
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Re: increasing fuel efficiency of engine

Postby Merlyn » Wed Nov 22, 2017 12:55 am

That's why, like it or not CR is here to stay for internal combustion engines.
Best all us older hands get on this CR roundabout or trail behind.
Cast adrift that is.
Remembering The Good Old days, when Chiefs stood watches and all Torque settings were F.T.

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Big Pete
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Re: increasing fuel efficiency of engine

Postby Big Pete » Wed Nov 22, 2017 9:22 am

I read the original Post, but it appears to have been translated using Google Translate and the meaning is not clear to me at all. Your later Post is written much more clearly.
I do not I see how it will be mechanically more efficient than a traditional engine. In a normal Reciprocating engine, although the "Lever arm" of the crank varies from "0" at TDC and BDC and to a maximum at Half Stroke, the pressure in the cylinder will merely drive the piston faster when the crank arm is small so that the instantaneous power generated at any crank angle would almost certainly be the same in a conventional engine as it would be for the same piston position in the engine in the link. (Power = Force x Distance/time)
You can't get power for nothing.

BP

BP
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Serguei
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Re: increasing fuel efficiency of engine

Postby Serguei » Fri Nov 24, 2017 12:47 pm

Dear Big Pete,
First at all I apologize for my English. I am only 7 years in Canada and I am trying to improve my English using every opportunity. And you encouraged me when you say "Your later Post is written much more clearly":-).
About our discussion. The main indicators for the engine of internal combustion are the moment and the capacity.
M= L*Fτ;
L- The “lever arm” on the crankshaft
Fτ =the tangential force;
Fτ =Fd*sin(ɣ + Ψ)/cos ψ; (1)
Fd –the force along the axe of the piston;
ɣ - The angle between axes of the piston and the connecting rod;
Ψ – The angle between axes of the piston and the crank;
Please note that the tangential force Fτ has meaning 0 in the TDC and in the BDC. Between this centers Fτ changes in accordance with the equation (1).
In the offered engine the “lever arm” is constant during all way.
It is known that the capacity (N) is defined by multiplying of the meaning of the moment(M) and the number (n)of revolutions and dividing by the time(t).
N =M*n/t;
The statistical meanings of the variations of the moments in the suggested design and in the conventional design during the turning of the power shafts from 0 till 180 degrees could be characterized by the average arithmetic values. The average arithmetic value of the moment in the suggested design is 1.83 times greater than the average arithmetic value of the moment in the existing design.

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Merlyn
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Re: increasing fuel efficiency of engine

Postby Merlyn » Sat Nov 25, 2017 1:41 am

Over to you BP I am thinking?
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Big Pete
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Re: increasing fuel efficiency of engine

Postby Big Pete » Mon Nov 27, 2017 1:31 am

Serguie you are obviously a keen young Engineer who is looking for good ideas everywhere and trying to put them together, so I congratulate you on being interested in the subject and spending time researching it. Your English is much better than most English peoples foreign Languages and you are obviously learning fast.

I apologise for not answering your last post earlier, but I have been thinking about how to explain it to you.

Going back to basics, Power is the rate of doing work, in the case of both a traditional engine with a crankshaft and the design you propose,

The work is the force on the piston X the distance moved. The force on the piston is obviously the pressure above the piston X the area of the piston.

Therefore in both types of engine the work done per firing stroke, would be the mean pressure X Piston Area X Length of Stroke.

So, if both engines have the same Bore, Stroke and running speed and are burning the same quantity of fuel per stroke, with the same combustion efficiency they should produce the same Indicated Power, for the same fuel consumption, so there would be no change in fuel efficiency.
The Tangential Force, FT you talk about, does not produce any movement, so it does absorb any power. It is a force that is neutralised by the resisting force of tension in the connecting rod, Force X Distance = Zero.


I agree that in a traditional engine the Torque produce by the engine will be proportional to the lever arm of the crank radius, in your proposed engine it will be proportional to the radius of the gear wheel driven by the Rack.

With your design the linear speed of the piston accelerates very rapidly at the start of the stroke and de-celerates very rapidly at the end of the stroke when compared with a conventional engine where the pistons accelerate and de celerate throughout the entire stroke, so the inertia forces on the piston and connecting rod will be much greater on "Your" engine.

With regard to lubrication it is much easier to lubricate a rotating shaft than a reciprocating movement, (Hydrodynamic Wedge Lubrication), in order to lubricate the racks and gear teeth there would have to be oil sprayers all round them.

Also, as an Engineer, I do not like the idea of these long, heavy racks swinging round at each end of the stroke, there would a lot of inertia to overcome and big forces to control.

Keep on asking the questions and thinking!

BP
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Serguei
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Re: increasing fuel efficiency of engine

Postby Serguei » Wed Nov 29, 2017 9:31 am

Hi Big Pete,
If you have one apple and I have one apple and I give you my apple and you give me your apple so in result each of us will have only one apple. But if you have one idea and I have one idea so in result we are both will have two ideas.:-)
I support your reasoning that “both engines have the same Bore, Stroke and running speed and are burning the same quantity of fuel per stroke, with the same combustion efficiency they should produce the same Indicated Power”. But, such a miracle English word “but”, we should note that the force which appears as the result of the interaction of the pressure and an area of the piston is divided into two forces, namely, the force which acts perpendicular to the wall of the sleeve and the force which acts along the connecting rod. And last one in its turn is divided again into two forces, namely the tangential force and the force which acts along the crank to an axis. It is this tangential force creates a torque M which is result of interaction of tangential force and a meaning of the crank. In this case power is defined in accordance with equation.
N = M x ω;
M- Torque, N X m;
ω- Number of the revolution per minute.
As you see here the meaning of the tangential force differs from the meaning of the force which is created as result of interaction of the pressure and an area of the piston. And more, meaning of the tangential force changes in accordance with an equation
Fτ =Fd x sin (ɣ + Ψ)/cos ψ; (1)
Fd –the force along the axis of the piston;
ɣ - The angle between an axis of the piston and an axis of the connecting rod;
Ψ – The angle between an axis of the piston and an axis of the crank;
As usual in the calculation is using the average arithmetic meaning of the tangential force because people did invent nothing to characterize the set of values of the phenomenon. Using the above mentioned approach we can compare the tangential force, the torque and the power in the conventional and the suggested engines. Please take into the consideration, that in the suggested engine the force, which is created in result of the interaction of the pressure and an area of the piston is interacting directly with the gear without a loses such as the force which is perpendicular to the wall of the sleeve and the force which is acting along the crank to the axis, which we can observe in the conventional engines.
About a “accelerates and a decelerates”. You are right. But, again this miracle English word “but” .It is well known that the revolutions in the engine are quasi-uniform. The uniformity of rotation is ensured by the flywheel. In the suggested engine a role of the flywheel will be as well as significant. Here, in our discussion, we are trying to analyze disadvantages and advantages. It is so pity that impossible to create an experimental model and check our considerations. May be the role of the flywheel will be sufficient or may be will be required an additional elements to compensate the acceleration and the deceleration.
About lubrication I agree. Well known three kinds of the lubrication, namely lubrication under pressure, spray and the combination of both early mentioned allow using any of them. Your question is right.
And, finally, about inertia. . In conventional engines as well as use so many parts, which are rotating and moving simultaneously, for example, the connecting rod and the crankshaft. The crankshaft has a very ugly view. The long history of the Otto engine overcomes so many deficiencies. The main requirement for the moving parts is the fine balance. The balancing of the crankshaft is the one of the last process. I understand your question and I think that there is an enough big area for finding solutions for the balancing of moving parts in the suggested engine.
I am very thankful to you for your questions, which push me to think more.
Best regards
Serguei


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