CA2731299A1 - Novel simpler and efficient internal combustion engine - Google Patents

Abstract

This invention mainly consists of a geometric novel system that can be mainly used as 1) an efficient internally heated combustion engine that can perform a high-efficient 2-stroke clean Otto or Diesel cycle 2) a simpler externally heated steam engine with no boiler requirement 3) an improved stirling engine system operating under two-phase flow conditions with high heat transfer rates from the heat source to the working gas. The new proposed geometry uses a novel concept system established between piston and cylinder that uses incompressible fluid like water as a medium to facilitate the sealing operation of the working fluid, gases for internal combustion engine configuration, steam for the steam engine or a gas/vapour to the stirling engine. The new sealing system totally avoids hot gases/ steam to escape from the cylinder during the combustion and expansion processes of the engine thermodynamic cycle. It also can eliminate the need of special lubricants in the cylinder walls as typically occurs in convention internal and external heated piston engines. This sealing concept allows injection of large amounts of water inside the cylinder that can be used in two different ways: a) for internal combustion engine configuration the water can be easily injected at the end of the expansion stroke to capture sensible heat from the gases producing steam that provides extra positive work in the expansion phase; b) for external heated steam engine, the water can be injected during the end of the compression phase against a hot surface producing steam necessary during the expansion phase. At the beginning of the compression phase water is injected against the steam reducing the cylinder pressure and the compression work; c) for the stirling engine liquid can be injected in the hot section by the displacer movement when located in the cold region.. Another extreme advantage is that for internal combustion engine applications, the geometry allows the use of an efficient simple scavenging pump outside the engine crankshaft area, allowing excellent scavenging process. This fact favors low-emissions production associated with possibility of achieving high amounts of work per cycle. Additionally the geometry favours the use of an efficient uniflow type scavenging procedure that can also uniquely use valves in both cylinder and piston that can favor engine cycle optimization. The possibility of using these valves allows the engine to easily perform operations close to Atkinson cycle. Alternatively, as an external heated steam engine, the use of valves or not can be adopted, depending on how complex and efficient the steam engine system is desired. Both these internal and external heated configurations are also very suitable as a cogeneration unit since water can be directly heated by the combustion gases and cylinder cooling walls without the need of complicated heat exchangers. The low-temperature of the sealing components, the absence of high-temperature lubrication, the possibility of not having valves can also make this design very suitable as a low-maintenance engine that can be used, as said above, for residential cogenaration systems or for third-world rural area power applications. For the stirling two-phase flow system can solve some of the problems associated with stirling engines in terms of the difficulties in transferring heat from the outside heat source and the working fluid. A liquid being injected against the hot surfaces of the stirling engine parts can easily remove heat and transfer it to the gas as part of the working fluid. This can simplify the heat exchanger components of this engine.

Description

Novel Simpler and Efficient Internal Combustion Engine This invention application as a novel internal combustion engine uses a new sealing concept between the piston and cylinder where incompressible fluid is used as a medium to seal the engine working gas. Because of that, the engine has several advantages over conventional ones: possibility of operating as a clean 2-stroke engine with extreme high efficiencies operating close to the Atkinson extended expansion cycle. This engine is also very suitable as a cogeneration unit since water can be directly heated by the combustion gases without the need of complicated heat exchangers.

BACKGROUND:

Traditionally internal combustion engines use metal rings in the piston to seal the combustion gases inside the cylinder. Lubricant oil becomes necessary not only to enhance the sealing but also lubricates the ring movement against the cylinder walls.
With time the oil is partially oxidized and needs to be changed. Specially in an Otto two-stroke engine the oil is inevitably burned since the fuel air mixture or just air for fuel injection systems is pumped to the cylinder from the lower part of the engine.
So, two-stroke engines despite of their simplicity burn significant amounts of oil releasing high amounts of unburned hydrocarbons to the environment. A conventional four-stroke burn much less oil engine minimizing this problem but it has limitations in terms of extending the expansion of the combustion gases due to its 4- stroke symmetric travel of the piston to effectuate a cycle. The new engine overcomes all these limitations:
1) It can operate in a very clean combustion process as a two-stroke engine without the problems of oil burning.

2) It can perform high-efficient 2-stroke cycles even not using valves due to the possibility of having excellent scavenge process due to the possibility of having good effective air pumping action.

3) If using valves on both cylinder and piston, in a manner much simpler than used by traditional four-stroke engines, it can easily approach an efficient Atkinson cycle where an extend expansion of the combustion gases can be executed.

4) It can also be used for cogeneration applications since the exhaust and engine heat can be easily transferred to water or another incompressible fluid.

5) The engine cost can be extremely low due to the average low temperature of the parts in contact to the combustion gases and the system with no valves can be even cheaper.

6) The engine can easily use large amounts of water injected at the end of the expansion work transforming sensible heat from the exhaust gas into latent heat changing phase from water to steam, which produces additional extra work. This can significantly increase engine efficiency. Traditional internal combustion engines cannot inject water at the expansion phase due to lubrication problems plus the complication of having an external water injection system.

7) The engine needs very little maintenance due to the simplicity of the sealing mechanism plus the fact that the lubrication oil is not in contact with the combustion gases.

Novel Simpler and Efficient External Heated Engine This invention application as a novel external combustion engine uses a new sealing concept between the piston and cylinder where incompressible fluid is used as a medium to seal the engine working gas. Because of that, the engine has several advantages over conventional ones: possibility of operating as a externally heated engine.
Steam can be provided externally by a boiler or in a much simpler proposed configuration, be generated inside the cylinder using a hot internal part where water is injected against it. This engine is also very suitable as a cogeneration unit since water can be directly heated by the exhaust steam without the need of complicated heat exchangers.

BACKGROUND:

Traditionally externally heated steam engines use metal rings in the piston to seal the combustion gases inside the cylinder. Lubricant oil becomes necessary not only to enhance the sealing but also lubricates the ring movement against the cylinder walls. In a conventional steam engine, steam needs to have few condensing water droplets otherwise it will create problems on engine efficiency and lubrication. The new engine overcomes several traditional internal combustion/ steam engine limitations:

a) It can operate in a very clean externally heated combustion process using gaseous, liquid or solid fuel. The continuous combustion process can provide ultra-low emissions.
b) It can use external heat sources other than burning fuel such as solar energy or steam from industrial processes.
c) It can also be used for cogeneration applications since the exhaust steam and engine heat can be easily transferred to water or another incompressible fluid.

d) The engine cost can be extremely low due to the average low temperature of all moving parts.

e) A relative easy way of internally producing steam is the use of internal hot parts inside the cylinder where water can impinge against it producing steam at the beginning of the expansion phase.

f) Water can also be injected as fine spray against the steam, to condense it at the beginning of the compression phase, reducing the negative work on the thermodynamic cycle. The condensed water will just accumulate with the rest of liquid water located at the bottom of the engine cylinder. Water can be injected in a direction without cooling much the piston walls. The piston and cylinder walls can also be coated with composite materials to reduce heat transfer losses from the working fluid. Traditional steam engines have more problems doing this because of the nature of the internal sealing required from engine piston rings and cylinder.

Because of these features, the engine has innumerous applications for both power generation and heat production:

A) Residential cogeneration that can be used to produce power in residences that today burn natural gas for heating purposes only. This will open a new market with more than 500 million houses worldwide.

B) Small high efficient generators in a $ 7 billion/ year market requiring extremely low-maintenance requirements.

C) It can be used on other applications where size and weight per power produced is not so critical.

D) It can use any source of fuel or heat for the externally heated configuration. This fact creates great flexibility of operating the engine in rural areas.

E) This is a unique design where there is no requirements to have a boiler dedicated to produce steam in the engine. Steam can be quickly produced every cycle internally inside the cylinder.

F) Conventional steam engines cannot easily inject water inside the engine cylinder because of limitations on efficiency and lubrication on the cylinder walls.
Also a complicated injection system would be required. The water sealing configuration facilitates the use of water from inside the engine cylinder to be pumped against either the cylinder hot part (expansion phase) or steam fluid (compression phase) G) The injection of water for either expansion or compression phase can be easily achieved by the piston movement inside the water, since a simple small pump system can be attached to it and used to promote compression of water inside the cylinder itself.

n SUMMARY OF THE INTERNAL COMBUSTION ENGINE INVENTION:

It is the obiect of the present invention to provide a more efficient, cleaner and simpler 15 internal combustion engine configuration.
This invention uses a typical engine crankshaft that can use self-lubricating bearings so that the lubrication of its components requires very little maintenance. it does not require an oil mist around it since the engine piston does not require oil for lubrication. The connecting rod is linked to a piston that has an inverted shape so that its moves inside a cylinder where there is a liquid, such as water that being incompressible behaves as an intermediate medium between the exhaust gases and the sealing system that prevent this liquid to escape from the cylinder. The engine can operate with or without valves. On Fig 1, a scavenging port and an exhaust valve are shown, and the later can be activated by pressure differential between the cylinder and the scavenging areas, but on Fig 2 there is no valves at all and rather inlet and exhaust ports. On Fig IA an alternative sealing system where the rings are located in the internal part of the moving piston, attached to the internal fixed cylinder where the exhaust valve is located. This sealing system receives a jet of water to cool it down at the moment a port is uncovered by the piston movement. Still on both Fig 1 and 2, there is a scavenge pump activated by the so called stationary piston located on the other side of the piston. This pump can be as large as desire, different than crankcase conventional pumps that have same displacement as the engine piston. A larger scavenge pump and the total absence of oil in the combustion chamber can provide clean fresh combustion air followed by a much cleaner combustion process than those obtained by traditional two-stroke gas engines. Similarly a fuel pump or a water pump can be easily incorporated in the other side of the piston as indicated on n Fig 1. The fuel pump can compress gas fuel and inject it at the beginning of the compression phase. A water pump can be used to repose the water lost inside the cylinder due to evaporation or leak from the engine piston seals, as shown on Fig 5.
Another water pump similar to the one shown of Fig 5 can be used to easily inject water inside the cylinder at the end of the expansion stroke to use exhaust gases heat to produce steam to convert into extra pressure and increase efficiency. Outside the engine the liquid level covers the engine cylinder and partially the piston so that engine rejected heat is in direct contact w/ water through the piston and exhaust gases (no heat exchangers).

Following Fig 2, the engine can perform a clean two-stroke cycle with no valves at all.
The scavenge and exhaust ports are located in the piston that moves and that is discovered when surpasses the piston seals. In this case a duct links the air compressed by the piston and the stationary cylinder through the piston seals and finally the cylinder.
Following Fig 3, the use of valves allows the break of the symmetry from the compression and exhaust phases of the two-stroke cycle, similar to a Miller cycle approaching an Atkinson cycle. One advantage at this point is that the 4-stroke Miller cycle partially uses twice the movement of the piston around the lower dead center to admit and reject some of the incoming air or mixture while in a 2-stroke, this is only used once with the addition that during this time the scavenging process is taking place.
After the ignition and combustion, the gases will expand pushing the piston upwards. The exhaust valve controlled by a spring will only open when the engine gas pressure drops below a certain value due to the expansion of the exhaust gases. Once it is open, the cylinder gas pressure will drop sharply allowing the scavenging valve, also controlled by a small spring, to open and inject air pushing more exhaust gas across the exhaust valve.

1f The exhaust valve in this figure is controlled by the movement of the piston as indicated.
As this exhaust valve opens, it changes the position of small arm of the valve control mechanism (see Fig 3) so that when the piston moves downward, it pushes the valve down until the cylinder gas pressure completely closes the valve. As the exhaust valve opens and the cylinder exhaust gas pressure sharply drops, the admission scavenging valve opens through pressure difference and help cleaning the cylinder with excess of scavenging air that was pumped by the scavenging pump. The piston starts moving downwards and the scavenging valve closes and the exhaust valve starts closing due to the valve control mechanism movement. As it closes, fuel can be injected as indicated by the fuel compressor that can easily be built in the stationary piston.
Alternatively, a compression ignition system can be used for a Diesel version of this engine.
At the end of the compression phase, fuel is well-mixed with the fresh scavenging air and combustion takes place similar for what occur for either Otto or Diesel cycles. The combustion gases expand pushing the piston upwards and now having a longer expansion phase than compression. That guarantees high values of efficiency similar to what happens to an Atkinson cycle. Fig 4 shows a system with no scavenging pump where the cylinder air recharging occurs due to the temporarily cylinder low-pressure system created during the cylinder blow down phase. This system uses an air admission valve operated by pressure differential from inside and outside the cylinder. In this case, the scavenging process is not as effective as the other configurations shown on Fig 2 and Fig 3, so that the combustion process is not as clean and efficient. However, Fig configuration reflects an engine with fewer moving parts so that cost and maintenance are big pluses for this proposed configuration.

SUMMARY OF THE EXTERNAL HEATED ENGINE INVENTION:

It is the object of the present invention also to provide a more efficient, cleaner and 15 simpler external heated engine configuration (Fig 5 and 6). One big advantage of this configuration over traditional steam engine configurations is that it does not need boilers to produce steam as a working fluid. It rather uses ax extreme simple water injection system to generate steam internally to the engine cylinder. This is possible due to the sealing system that uses water as the medium that facilitates water injection and steam generation internally to the engine. Finally the idea of having liquid present inside the cycle can also be applied to Stirling engines: Fig 7 shows an scheme of a classical free piston Stirling engine operating with an internal liquid injection system connected to the engine displacer. So that at the end of the displacement stroke, water is injected against the hot cylinder walls, enhancing heat transfer and therefore increasing cycle efficiency.
STEAM ENGINE OPERATION- Similarly to the internal combustion engine version, this configuration uses a typical engine crankshaft that can adopt self-lubricating bearings so that the lubrication of its components requires very little maintenance. It also does not require an oil mist around it since the engine piston does not require oil for lubrication. The connecting rod is linked to a piston that has an inverted shape so that its moves inside a cylinder where there could be a liquid, such as water that being incompressible behaves as an intermediate medium between the steam and the sealing system preventing steam to leak from the cylinder. If there is no liquid inside the cylinder (dry mode), than the piston rings are located around the central body (stationary) of the cylinder. The engine can operate with and without valves. On Fig 5, the engine shown has valves activated by pressure difference (cylinder interior and vapour pressure inside injector) and exhaust ports. Similarly a water injection pump can be easily incorporated in the other side of the piston as indicated on Fig 5. This pump is actuated at the end of In the compression phase and injects water against the Hot Spot Cylinder that receives heat from any External Heat Source. The Inverted Piston has a central body that is introduced as the piston moves down against the Hot Spot Cylinder. As the water is pumped internally through small ducts inside the Inverted Piston, it is released against the Hot Spot Cylinder creating vapour almost immediately. This vapour will ultimately increase the cylinder pressure pushing the Inverted Piston upwards during the expansion phase. A check valve can be used in the water pump system rod tip. The internal generation of steam enormously simplify the steam engine system, eliminating the need for a boiler. Similarly, water could also be injected at the beginning of the compression phase against the steam volume to reduce compression work. The interior of the cylinder can be coated with an insulating material to reduce direct heat transfer from the steam/
water to the piston, improving steam cycle efficiency.

STIRLING ENGINE OPERATION - Fig 7 shows a classical view of a free piston stirling engine: The piston and the displacer connected plus the regenerator. The insertion of a simple internal liquid pumping system is the main innovation on this configuration. At the position where the displacer is going downwards and the working fluid is going the hot section of the engine, liquid is injected against the hot walls changing phase, increasing the cylinder pressure and enhancing heat transfer from the hot walls to the working fluid. Therefore, heat transfer rates are enhanced and despite the relative lower temperatures, less heat losses will guarantee a better efficiency. Also as the gas/vapour working fluid moves to the colder engine cycle, a partial condensation of the vapour favours heat transfer of the working gas to the cylinder walls.

industry Industrie ?,rPJlj Cenada 'tiUD
Ceneda Application for Letters Patent ININIIIINIINIINI
INIINIIANINIIIINiI

CiPO OPiC E001217096 Novel Heat Engines Luiz Claudio Vieira Fernandes Table of Contents INVENTOR:

Luiz Claudio Vieira Fernandes 4 Boswell Ave, Toronto, ON, M5R 1 M4 Canada Tel: (647) 981-0956

Claims (18)

1. The use of a liquid (water) as an intermediate medium between the working fluid such as exhaust gases inside an engine cylinder and a low-temperature sealing system improving sealing effectiveness of internal combustion engines, as shown on Fig 1.

2. The use of an inverted shape piston that operates in an environment created by a cylinder filled with liquid that act an effective sealing mechanism, as shown on Figs 1 to 6. The inverted piston arrangement allows the liquid from claim 1 to remain stationary either on fig 1 or 1A.

3. The use of a injection of water against the piston sealing at the end of every stroke during the scavenging phase as shown by figure 1A. This water will maintain the seal cool so that oil lubrication is not necessary.

4. The use of an scavenge pump that operates on the other side of the piston described on claim 2 and that can supply large amounts of air or air-fuel mixtures to the engine cylinder, as shown on Fig 1.

5. The use of a liquid medium as described on claim 1, an inverted piston as described on claim 2 and an scavenge pump as described on claim 4 that can use an admission valve located at the mentioned piston and that allows a uniflow scavenging process to occur that is not limited by the movement of the piston as normally occurs with cylinder ports, as shown on Fig 1.

6. The use of an engine operating under a two-stroke system using the inverted piston as mentioned on claim 2, the liquid sealing mechanism as described on item 1 and the scavenge pump as described on claim 4 and that can execute a two-stroke engine internal combustion cycle with no valves and just inlet and exhaust ports as shown on Fig2.

7. The use of an engine operating under a two-stroke system using the inverted piston as mentioned on claim 2, the liquid sealing mechanism as described on item I
and the scavenge pump as described on claim 4 and that can execute a two-stroke engine internal combustion cycle with a unique inlet valve at the piston and exhaust valves at the engine cylinder, as shown by Fig 3.

8. The use of and engine as described on claim 7 with a simple valve control mechanism that can be either activated by pressure difference or by the piston movement as sketched on Fig 3.

9. The use of an extended expansion concept in an engine as described on claim 7 where the exhaust valve opens initially by pressure difference and it closes by the movement of the piston. The expansion stroke is much longer than the compression stroke and the scavenging process can use substantial travel of the initial downward movement of the engine. The admission valve, located at the piston, only opens after the exhaust valve opening has significantly decrease the engine cylinder pressure described above. The admission valve closes by pressure difference from the scavenge pump delivery and the engine cylinder. A small spring can also be used with the admission valve to make more difficult its opening.

10. The use of an engine with a sealing mechanism as described on item 1, an inverted piston as described as claim 2 that uses an admission valve that opens by pressure difference induced by the movement of exhaust gases through exhaust ports in the two-stroke engine as indicated by Fig 4.

11. The use of the exhaust gases and engine cooling being in direct contact with water to heat it directly in a very efficient manner as described on Fig 1. The engine is based on engine description on claims 6, 7 and 8.

12. The use of an engine as described on claim 11 and that internally injects water during the expansion stroke, removing heat from the exhaust gas and using it to produce steam, further increasing the exhaust gas pressure, significantly enhancing the engine overall efficiency. This water injection in significant amounts is only possible due to the sealing mechanism described on claim 1 and the use of an internal liquid pump attached to the movement of the piston as shown of Fig 5.

13. The use of the an engine that uses a sealing mechanism as described on claim 1, an inverted piston as described on claim 2 and that uses an internal water pump to inject water against a hot spot inside the engine cylinder as shown of Fig5. That creates steam internally in an engine that operates with steam as a working fluid and that does not require an external boiler, as shown on Fig 6.

14. The use of a sealing mechanism as described on claim 1 and the concept of steam generation as mentioned on claim 12 that uses a simple water/ liquid pumping system internally to the engine cylinder and that is activated by the piston movement.

15. The use of a liquid pumping system described on claim 13 and sketched on Fig 5 that uses internal circuits in the moving piston to direct to a hot area inside the engine being heated externally. The water in contact to this hot area produces steam necessary to produce pressure inside the cylinder and expand producing useful work.

The water can be injected under pressure and velocities inside the cavities of the hot spot body.

16. The use of a water injection system in the steam engine described on claim 13 and that can be injected by an internal liquid pumping system as described on claim 15 into the steam during the compression phase reducing the cylinder engine pressure and consequently the negative compression work.

17. The use of an liquid inside a stirling engine sitting on the bottom of the cold zone that can be pumped internally by the displacer movement as shown on Fig 7. A small piston is attached to the displacer mechanism as sketched by the Fig 7 that can pump simply and effective inject liquid against the hot surfaces of the engine.

18. The use of the pumping system described on claim 15 and that can be pumped to the hot zone by the time the displacer displaces gas to the hot section. A two-phase flow system is formed and an enhancement of the heat transfer mechanism from the heated walls to the working gas can be executed. Similar condensation mode occurs once the liquid looses heat to the cooling engine zone, that reduces engine negative work. A
sketch is shown on Fig 7.