CA3189414A1 - Using a fluid as a virtual secondary compression piston for an internal combustion engine. - Google Patents

Abstract

The invention relates to a secondary compression system for an internal combustion engine using a fluid as a second virtual rapid variable-stroke compression piston. Said system enables the engine to behave like a variable compression ratio engine. It consists of an extension at the dead volume of the engine in the form of a relatively long and narrow duct in the cylinder head of the engine, serving as a bore for the virtual piston and opening into a valve. Said system aims to add a second compression of the air/fuel mixture when the piston is near top dead centre, by introducing a high-pressure jet of fluid via a valve controlled by the computer. Said introduction is manifested as a jet of fluid in a relatively long and narrow duct without being mixed with the air/fuel mixture. This makes it possible to regulate the pressure at the time of combustion according to the load and to increase the amount of material in the cylinder while maintaining parity with stochiometric combustion.

Description

Description Title of the invention: Use of a fluid as a virtual piston secondary compression for an internal combustion engine.
The present invention relates to a system for improving energy efficiency internal combustion engines and the reduction of polluting emissions which applies to all types of internal combustion engines, whether ignition ordered, HCCI (Homogcncous Charge Compression Ignition) or Diesel. In using a fluid as a second compression piston.

[0002] In recent years, several innovations have been made to improve energy efficiency and reduce polluting emissions from diesel engines.
combustion internal. Among these: Downsizing with air supercharging by a turbocom-presser, the adoption of direct injection which allows the air to be cooled admitted and by which generates a low charge stratified mixture and the recirculation burnt gases EGR (Exhaust Gas Recirculation) to control low oxygen levels charge.
Only, it should be noted that on the one hand, these solutions do not manage to answer to requirements of environmental standards in a satisfactory manner and on the other hand, we had to favor operation at low rpm and low load at the expense of the one above rpm and full load, in addition to the problem of unreliability that results.

[0003] To this end, among the desired innovations, motors with compression ratio variables which adapt according to the load. However, most breakthroughs accomplished are totally mechanical, the consequences of which are linked to moving parts born are not negligible: such as the increase in weight, friction, size, and number of moving parts and as well as the high position of the center of gravity. By elsewhere, there are many works that are very interested in the focus point of an HCCI-type motor whose main constraint to be overcome is power control the moment when the detonation engages independently of the charge.

[0004] The present invention provides a modification at the level of the engine dead volume internal combustion with the addition of an extension in the form of a duct relatively long with a small section in the cylinder head (2) of the engine which leads to a valve (3) controlled by the computer. Engine operation will remain globally even and unchanged.

[0005] Indeed, once the piston (1) has done most of compression, the air/air mixture fuel (or air only for Diesel engines) is found basically confined in the dead volume (4 and 5). Right now, the second compression is produced by the introduction of a fluid via the valve (3). This valve can be assimilated to a micro-valve or an injector controlled by the computer. This fluid will hunt the air/fuel mixture of the cramped part resembling a long and narrow of dead volume (5), to concentrate it almost totally at the level of the part in-lower dead volume (4), until reaching the pressure or temperature coveted regardless of engine load.

[0006] From the moment that the contact between the fluid introduced and the air/
fuel is carried out in a place with a relatively very small section and very little di-vergent in the direction of the flow (5), the scale of the structures whirlwinds is conditioned by the section of the conduit and thus, the mixing of the fluid with the blend air/fuel is extremely limited or even impossible. In addition, gases burnt from previous cycle stuck in the dead volume duct (5) after the exhaust cheek the role of insulation between the air/fuel mixture and the compression fluid.
Considering of these facts,

[0007] = The fluid will have the effect of a fast piston whose stroke is variable and depends on the amount of fluid introduced, in other words, depends on the time opening of the micro-valve (3). Therefore, the engine behaves like an engine with variable compression ratio depending on the load.
= Heating by compression of the air/fuel mixture by introduction of fluid is carried out even if the introduced fluid is relatively cold.

The present invention also makes it possible to control the self-ignition moment for the HCCI type engine and to reach the self-ignition conditions at pro-portions less poor and closer to stoichiometry, independently of there load whether for Diesel or HCCI engines. On the other hand, she increases at the times the amount of material in the cylinder while being at proportions close to the stoichiometry (air + fuel + compression fluid) and the size of the dead volume per relative to the cubic capacity (the addition of the duct (5)). Therefore, she decreases the rate of compression (compression ratio) of the engine without decreasing the pressure.
As a result, at the time of combustion, the peak temperature will not be as pupil than if the compression ratio were higher and the amount of material lesser. By therefore, harmful emissions such as nitrogen oxides NO, and monoxide of carbon CO will be greatly reduced.

[0009] Furthermore, the present invention makes it possible to operate type motors controlled ignition or HCCI with a cycle close to that of Sabathe without input of additional heat in relaxation. Indeed, during expansion, the fluid introduced who is extremely dense, as it mixes with gases burnt, go absorb the thermal energy of combustion. Thus, the pressure level will be maintained raised longer while decreasing the temperature of the gases, despite that the total gas volume increases. which will increase the torque and improve the engine fuel efficiency.

[0010] The lower part of the dead volume will be given the name of bedroom combustion (4) because this is where the mixture is essentially air/fuel at time of combustion. As for the cramped part of the dead volume which resembles has a duct (5), it will be given the name dc compression chamber, and in which there is no combustion due to lack of fuel, especially in the part near the micro-valve (3) for introducing the compression fluid. By against, for the lower part adjacent to the combustion chamber, it can be the pro-length of the combustion chamber according to the various parameters, such as that the load, temperatures and pressures of the air/fuel mixture and the communication fluid pressure. The compression chamber can be provided with fins in order to have the least turbulent flow possible, to minimize mixing between the compression fluid and the air/fuel mixture.

[0011] It is the computer that manages the moment of introduction of the compression fluid in the dead volume compression chamber (5), depending on the different parameters including it features like the compression fluid pressure.
roo121 = If the engine is of the Diesel type, the fluid pressure may be lower than peak of combustion pressure because the micro-valve (3) for introducing the fluid compression can be closed at the time of injection of fuel into the cylinder.
= If the engine is of the spark ignition type, the pressure of the compression fluid may be lower than peak combustion pressure because the micro-valve (3) for introducing the compression fluid can be closed when the candle starts combustion.
= If the motor is of the HCCI type, two cases arise:
I00131 a. If the pressure of the compression fluid is higher at the peak pressure of combustion, the micro-valve (3) for introducing the compression fluid may be in the open position when combustion begins. By therefore, the introduction of the fluid may be delayed until, even if the piston (1) exceeds the top dead center and begins the expansion stroke.
b. If the compression fluid pressure is lower at the peak pressure of combustion, the fluid introduction micro-valve (3) must be closed at the time of combustion. Therefore, the introduction of the fluid must be advanced and the start of combustion will be caused by the piston pressure (1) when it reaches top dead center.
[00141 Several fluids can be used such as gases exhaust, ambient air, liquid nitrogen and water. These fluids will be used to recover part thermal energy burnt gases escaping from the engine before their introduction into the combustion chamber com-engine pressure (5) to reach relatively cold temperatures compared with those of combustion but hot enough not to prevent the burning in the right conditions. For this, an electric heater is provided.
adjustment of the temperature, particularly during cold start phases upstream of the valve introduction of the fluid (3). The essential steps that the fluid of compression suit before introducing it into the compression chamber of the combustion engine internal are as follows:
1. Low pressure compression fluid intake.
2. Generation of the high fluid pressure by at least one compressor or a pump.
3. Accumulation of high pressure compression fluid in a ramp.
4.Heating the fluid at high pressure by the exhaust gases of the engine.
5. Electric heating if there is insufficient heat.
6. Introduction of fluid into the engine compression chamber.
[0016] In the case where the compression fluid is in a state:
[0017] = liquid before heating (water or liquid nitrogen), the high pressure is generated using a high pressure pump.
= gas before heating (exhaust gas or ambient air), the high pressure is generated using at least one well-cooled high-pressure compressor to limit the work spent on compression.
[0018] A high compression fluid storage ramp pressure is also essential thinkable. Furthermore, due to the fact of having fluid under high pressure in re-servos, allows it to be used to activate the micro-valve (3) which is already very light and small with high precision. On the other hand, this micro-valve (3) is there to ensure a pressure drop in the flow of the fluid and thus limit At maximum leakage when closed. Whereas, tightness is ensured by valves which are activated as soon as the engine is stopped in order to preserve the pressure of fluid in the ramp.
[0019] In the case where the fluid is in gaseous state at low pressure (atmospheric pressure) such as air or burnt gases, the high pressure is generated by compressors auxiliaries separated from the engine. Compression by compressors auxiliaries separated from the engine, provides the following advantages:
[0020] = To be able to recover part of the kinetic energy of the vehicle in the form of compressed gas using the compressor as a brake.
= Be able to operate the motor as an air motor without fuel consumption at brief moments when excess fuel is available compressed gas.
= To be able to cool the engine by compressed gas from the inside by doing operate as a pneumatic motor.

[0021] In the case where the fluid is fair, although fair contains 20% oxygen, this does not does not pose a problem of excess oxygen for the combustion reaction or for there NO production. Because this air is isolated in the compression chamber of the volume dead (5) when burning. On the other hand, it is relatively cold. Of more, the air that serves as an oxidizer perfectly mixed with the fuel is confined essen-partially in the combustion chamber of the dead volume (4) to proportions and well-balanced conditions of stoichiometry and combustion.
[0022] In the case where the compression fluid is di-nitrogen (N2), air or burnt gas exhaust: the fluid is in a supercritical state whether upstream of the microphone-valve (3) in the high pressure generation circuit or downstream, After the introduction of the fluid where it undergoes expansion.
In the case where the compression fluid is water. ( the water is more practical on large installations where the temperature of the exhaust gases is quite high and steady). two cases arise:
[0024] = The case where the water is in a liquid state or supercritical upstream of the valve introduction of water (3), the pressure must be greater than 221.20 bar where the exhaust gas thermal energy recovery exchanger is a simple exchanger without phase change and water introduction valve in the dead volume compression chamber is likened to an injector.
Downstream of the water introduction valve (3), once this fluid has been introduced and after undergoing expansion, it becomes a mixture of steam and liquid.
= The case where the water is in a superheated vapor state upstream of the valve introduction of water (3), the pressure must be less than 221.20 bar.
The exchanger will be assimilated to a boiler with liquid phase separation and steam, as for the valve (3), it will be likened to a micro-valve.
[0025] Finally, a significant part of the energy expended for the second compression will come from the thermal energy recovered from the exhaust gases, particular when the fluid is liquid nitrogen. which will help to improve the yield engine energy as well as the reduction of carbon dioxide CO2 product.
In summary, the present invention improves the efficiency overall engine energy and limits the polluting emissions produced without modifying the structure general and the operation of the internal combustion engine, thanks to the features following:
[0027] = Extract excess combustion thermal energy to convert it to mechanical work.
= Generate the most optimal pressure and temperature conditions of combustion for internal combustion engines of any type, independent depending on the load.

= Recover part of the thermal energy from the exhaust gases.
= Recover part of the kinetic energy during braking.
= Save some of the work needed for compression.
= Decrease the maximum peak combustion temperature.
= Initiate compression combustion for HCCI engines.
= Check the moment of self-ignition for HCCI motors.
= Operate Diesel and HCCI engines at lower proportions poor and close to stoichiometry.
Explanation of drawings [0028] The [Fig.1] represents a section of a four-stroke engine to which was added the dead volume pipe in the cylinder head (2) and the valve for introducing communication fluid pressure (3) and (1) is the piston.
[0029] The [Fig.2] represents a section of the dead volume of the engine with the bedroom combustion (4) and the compression chamber (5).
[0030] The [Fig.3] represents the shape of the dead volume of the engine in three dimensions with combustion chamber (4) and the compression chamber (5).

Claims

Claims [Claim 11 [added] A system for motors with internal combustion, including process is to introduce into the dead volume a fluid called fluid of compression pressure, while ensuring a heterogeneous mixture at the time of the initiation of combustion where, we distinguish the part of the dead volume essentially containing said introduced compression fluid and that the dead volume containing essentially air or the air/air mixture fuel.
[Claim 21 [added] According to claim 1, said system is characterized in that that it includes at least one chamber called the compression chamber, and at least one valve at the end of said so-called compression chamber compression chamber valve. Said valve of the chamber of compression introduces into said compression chamber said compression fluid: in predefined quantities depending on the load and the engine speed, and at a relatively cold temperature compared to the temperature of the burnt gases produced by combustion. Said room compression is in the form of a duct forming part of the dead volume and communicating with the combustion chamber. The said chamber of compression has a relatively small cross-sectional area or can be equipped with fins to limit mixing before priming the combustion, between said compression fluid and air or the air/air mixture fuel.
[Claim 31 [added] According to claim 1, a system of generation of the pressure and temperature of said compression fluid is characterized in what it may include.
-One or more compressors, in the event that said compression fluid is type to be in a gaseous state before putting it under high pressure.
- One or more pumps in the case where said compression fluid is type to be in a liquid state before putting it under high pressure.
-One or more heat exchangers heating said compression fluid, by recovering the thermal energy produced by the combustion engine internal or its accessories, such as the heat of the exhaust gases.
-One or more heat exchangers cooling said combustion fluid pressure.
-One or more electric heaters.
-One or more reservoirs of said compression fluid, waterproof and resistant to the pressure and the temperature of said compression fluid.