Abstract:
A reciprocating internal combustion engine ( 10 ) which comprises a tank ( 23 ), at least one cylinder ( 11 ), a piston ( 12 ) that can perform an axial reciprocating movement housed within this cylinder, this piston including a head and an arm hinged to this head, and at least one intake valve ( 19 ) and one exhaust valve ( 20 ) provided on the cylinder above said piston ( 12 ) and above two injectors ( 21   a  and  21   b ). The engine ( 10 ) is equipped with a device ( 27 ) for producing, by electrolysis of water, gaseous dihydrogen that is fed in the cylinder ( 11 ) and an explosion starts moving the piston ( 12 ) beyond a top dead center (TDC). A predetermined volume of water is then injected and instantaneously vaporized by the heat produced by the explosion of the gaseous dihydrogen. The hot steam pushes the piston ( 12 ) towards the bottom dead center (BDC) where the steam is then discharged through the exhaust valve ( 20 ). This engine only produces steam and thus is clean.

Description:
[0001]    This application is a national stage completion of PCT/IB2010/001242 filed May 26, 2010 which claims priority from French application Ser. No. 09/53465 filed May 26, 2009. 
       TECHNICAL SCOPE 
       [0002]    The invention relates to a method for operating a reciprocating internal combustion engine comprising a water tank, at least one cylinder, a piston that can perform an axial reciprocating movement housed inside this cylinder, this piston including a head and an arm hinged to this head, and at least one intake valve and one exhaust valve provided on the cylinder above said piston, method using gaseous dihydrogen. 
         [0003]    It also relates to a reciprocating internal combustion engine comprising a water tank, at least one cylinder, a piston that can perform an axial reciprocating movement housed inside this cylinder, this piston including a head and an arm hinged to this head, at least one intake valve and at least one exhaust valve provided on the cylinder above said piston. 
       PRIOR TECHNIQUE 
       [0004]    There are many engine types based on the combustion of a fuel, in particular of a fossil fuel. The operating principle of these engines is well known, even though important improvements aiming to increase the efficiency, decrease the consumption and reduce pollution have been made during these last years and still remain to be made. It is moreover known that many natural energy sources, and mainly the fossil fuel reserves, are becoming scarce. Furthermore, agriculture, whose products could allow generating oils or ethanols, in particular from rapeseed and sugar cane, must first of all allow feeding the human and animal population. The agricultural resources are no more sufficient today to achieve these goals. 
         [0005]    It is thus advantageous to look for sources of energy that both are abundant and have the advantage of being renewable to provide for the constantly increasing needs. The sun and the wind are already widely used to produce electrical energy, but there is the problem of storing this energy, which reduces the scope of its use. 
         [0006]    Freshwater may represent an appealing solution, but the global warming shows that this resource also may become scarce, since it is absolutely indispensable to provide for the needs of the human population, of animal life and of vegetal life. 
         [0007]    On the other hand, sea water represents 70% of the surface of the earth and regenerates with rain and ice melt. Using sea water as a source of energy may represent an interesting alternative for the current sources of energy, provided a simple, cost-effective and efficient means is set up for exploiting it with a view to energy production. 
         [0008]    The current reciprocating engine, powered by fossil fuels or synthetic fuels, either two or four-stroke, still represents today one of the most efficient ways to produce mechanical energy that can be directly used for ensuring all drive, propulsion, traction or similar functions immediately exploitable. Indeed, the pressure exerted by a detonation on the head of a piston of an engine of this type is approximately perpendicular to its surface and causes its displacement, generating the rotational movement of an output shaft of this engine. Even though the rotary devices such as the Wankel engine and the quasiturbine have been developed to avoid the obligation of converting a reciprocating movement into a rotating movement, the angle with which the pressure of the explosion or of the expansion is exerted is less favorable than on a reciprocating engine. One will note that the quasiturbine offers a slightly better angle than that of the Wankel process. 
         [0009]    One of the main drawbacks of the current reciprocating engine is due to the fact that the explosion which generates an intense release of energy takes place while the piston is at the top dead centre (TDC). At this moment, the lever arm defined by the angle of the rod and the centre of the crankshaft is the smallest. 
         [0010]    In order to have ideal conditions, the explosion in the reciprocating engine should take place while the rod is horizontal with respect to the axis of the crankshaft, that is to say, when the lever arm is also at its maximum. Certain systems, such as the gun engine, suggest postponing the explosion so that its maximum effects take place when the piston of the corresponding reciprocating engine has passed its top dead centre (TDC) by several tens of degrees. 
         [0011]    It results from this that the current explosion engines, which use fossil or similar fuels, even though they are relatively efficient, do not allow producing mechanical energy in optimal conditions. Furthermore, the use of fossil fuels, which are in the process of depletion, is deemed to stop in a relatively close future. Finally, the use of fossil fuels is polluting, since it releases enormous quantities of carbon dioxide and unburnt particles, which are partly responsible of the climatic warming and the pollution of our atmosphere. 
       DESCRIPTION OF THE INVENTION 
       [0012]    This invention offers an alternative that aims to eliminate the pollution due to the exhaust gases usually produced by the current heat engines, by proposing an internal combustion engine whose operation is optimized in such a way that the energy produced during the operating cycle is best used to generate mechanical forces, while eliminating the use of fossil fuels, which are difficult and dangerous to extract, and using substances that are indefinitely renewable on the planet. 
         [0013]    To that purpose, the method according to the invention is characterized in that it includes the following steps: 
         [0014]    a.—a first step, during which a predetermined volume of gaseous dihydrogen and a predetermined volume of a gaseous mix containing oxygen are fed into a space of said cylinder located above the head of said piston, 
         [0015]    b.—a second step, during which the gaseous dihydrogen fed into the cylinder is made to explode at the moment when the piston has passed the top dead centre (TDC), 
         [0016]    c.—at least one third step, during which a predetermined volume of water is injected in said cylinder, in a space located above said piston, to vaporize instantaneously this water under the influence of the heat produced by the explosion of the gaseous dihydrogen and to cool down the engine, and 
         [0017]    d.—a fourth step, during which the steam produced by the evaporation of the injected water and the combustion of the gaseous dihydrogen is exhausted. 
         [0018]    Advantageously, the method includes a preliminary step, during which, by electrolysis of the water of said tank, gaseous dihydrogen is produced, of which at least a predetermined volume is taken during said first operating step of the engine. 
         [0019]    During said preliminary step, salt water contained in the tank is used preferably for producing gaseous dihydrogen by electrolysis and cooling down the engine. 
         [0020]    Said first, second and third steps of the operation take place preferably while said piston passes from the top dead centre (TDC) to the bottom dead centre (BDC), while said fourth step of the operation takes place while said piston passes from the bottom dead centre (BDC) to the top dead centre (TDC). 
         [0021]    In a particularly advantageous way, said engine comprises several cylinders, each including a piston housed in one of said cylinders, and the whole of the first, second, third and fourth steps are performed individually in each of the cylinders of said engine, each of said steps performed in one of the cylinders being shifted in time with respect to the corresponding step performed in another of said cylinders of said engine. 
         [0022]    Also to that purpose, the internal combustion engine according to the invention, as defined in the preamble, is characterized in that it includes: 
         [0023]    a.—means for feeding, during a first step, a predetermined volume of gaseous dihydrogen and a predetermined volume of a gaseous mix containing oxygen into said cylinder, into a space located above the head of said piston, 
         [0024]    b.—means for producing, during a second step, the explosion of the mix of gaseous dihydrogen and oxygen fed into the cylinder, at the moment when the piston has passed the top dead centre (TDC), 
         [0025]    c.—means for injecting, during at least one third step, a predetermined volume of water into said cylinder, into a space located above said piston, to vaporize instantaneously this water under the influence of the heat produced by the explosion of the gaseous dihydrogen and the oxygen and to cool down the engine, and 
         [0026]    d.—means for exhausting, during a fourth step, the steam produced by the evaporation of the injected water and the combustion of the gaseous dihydrogen. 
         [0027]    The engine comprises preferably means for producing gaseous dihydrogen through the electrolysis of the water contained in said tank. 
         [0028]    In an embodiment variant, the production of the gaseous dihydrogen may include means for performing high-temperature electrolysis. 
         [0029]    Preferentially, said tank contains salt water for producing gaseous dihydrogen by electrolysis. 
         [0030]    According to an advantageous embodiment, said means for feeding a predetermined volume of gaseous dihydrogen during a first step comprise an injector. 
         [0031]    In addition, said means for feeding a predetermined volume of a gaseous mix containing oxygen during a first step comprise an intake valve. 
         [0032]    The means for injecting a predetermined volume of water of said tank into said cylinder may comprise an injector associated with an injection pump. 
         [0033]    In the case of an engine with several cylinders, each comprising a piston housed in one of these cylinders, it includes advantageously control means so that, in each of the cylinders, the steps corresponding to one of the cylinders are shifted in time with respect to the corresponding steps in each of the other cylinders. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0034]    The present invention and its advantages will be better revealed in the following description of an embodiment given as a non limiting example, in reference to the drawings in appendix, in which: 
           [0035]      FIG. 1  represents a view showing the principle of the engine according to the invention, 
           [0036]      FIG. 2  is a view illustrating a first phase of the operating cycle of the engine of  FIG. 1 , 
           [0037]      FIG. 3  is a view illustrating a second phase of the operating cycle of the engine of  FIG. 1 , 
           [0038]      FIG. 4  is a view illustrating a third phase of the operating cycle of the engine of  FIG. 1 , and 
           [0039]      FIG. 5  is a view illustrating a fourth phase of the operating cycle of the engine of  FIG. 1 . 
       
    
    
     BEST WAY OF REALIZING THE INVENTION 
       [0040]    Referring to  FIG. 1 , the internal combustion engine  10 , as it is represented schematically in a first simplified version, includes one single cylinder  11  in which a piston  12  having a reciprocating linear movement is housed, attached to a rod  13  mounted rotatably at one of its ends  14  on a rotary flywheel  15  mounted on a central shaft  16 , this rod  13  being furthermore hinged at its opposite end  17  on piston  12 . Above the cylinder  11 , the engine block  10  comprises a cylinder head  18  in which are housed, in particular, an intake valve  19 , an exhaust valve  20 , a first injector  21   a , a second injector  21   b  and a spark plug  22 , or similar, whose functions will be defined later. The intake valve  19  is mounted in the cylinder head  18  at the end of an intake piping  19   a  on which an air filter  19   b  is mounted. 
         [0041]    The engine  10  is associated with a water tank  23 , for example salt water, with an accumulator battery  24  and an alternator  25 , driven by flywheel  15 , for example via a belt  26 , for recharging the accumulators  24 . In the example of embodiment described, the tank  23  contains an electrolysis device  27 , arranged to produce gaseous dihydrogen by electrolysis of the salt water contained in tank  23 . Obviously, this electrolysis device  27  could be located also outside of tank  23 . The electrolysis device  27  is connected, via a dihydrogen supply circuit  28  with injector  21   a , through an injection pump  28   a  mounted on the supply circuit  28 . The tank  23  is also connected, via a water supply circuit  29 , to an injection pump  30  coupled with injector  21   b  arranged to inject pressurized water into the space defined by the top of piston  12  and the top of cylinder  11 . 
         [0042]    During operation, a small quantity of gaseous dihydrogen is produced by electrolysis, preferably during a preliminary step, and the engine  10  is fed during a first step by injecting a predetermined volume of this gas through the supply circuit  28  connected with injector  21   a . The dihydrogen is used as fuel and air or oxygen is added as oxidant via the intake piping  19   a  ending in the space defined by the top of piston  12  and the top of cylinder  11 , through the intake valve  19 . During another operating step, liquid salted water is injected via the supply circuit  29  connecting the bottom of tank  23  to injector  21   b  through injection pump  30 . 
         [0043]    As a variant, the gaseous dihydrogen required for the operation of engine  10  may be produced according to a high-temperature electrolysis process, which requires an auxiliary water circulation device. This equipment, which implies means for vaporizing the water coming from tank  23 , is represented by pipes  31  and  32  ending in cylinder head  18 . 
         [0044]    The classical spark plug  22 , used in the internal combustion engines, which requires usually a coil-contact breaker set, may be replaced in the present case with a piezo-electric system, which has the advantage of low electrical power consumption. This supply is represented schematically under item  33 . This solution can be used because the explosion of the hydrogen requires only a very low energy for taking place. 
         [0045]    The operating steps of the engine will be described more in detail with reference to  FIGS. 2 to 5 , which illustrate the principles of the method according to the invention.  FIG. 2  illustrates a first step during which a volume of air is drawn in at the top (on the figure) of cylinder  11  as shown by arrow A, this aspiration being due to the depression produced in cylinder  11  when the piston  12  moves down. In a slightly shifted way, a predetermined volume of gaseous dihydrogen produced by electrolysis during a preliminary step is injected at the top (on the figure) of cylinder  11  through injector  21   a , as shown by arrow B. Thus, the space between the top of piston  12  and the top of cylinder  11  is filled with an explosive mix of gaseous dihydrogen and air. 
         [0046]      FIG. 3  illustrates the second step, during which the explosion of the mix of gaseous dihydrogen and air is triggered off by means of a spark produced by spark plus  22 . This explosion has the effect of generating a pushing force on piston  12 , causing its displacement downwards (on the figure), actuating flywheel  15  thanks to the coupling of piston  12  and flywheel  15  by rod  13 . 
         [0047]    The following step, illustrated by  FIG. 4 , consists in injecting, through injector  21   b , a certain quantity of water taken from tank  23  into the space located between piston  12  and the top of cylinder  11 . The feeding by injector  21   b  is represented schematically by arrow C. Since this space has been carried to a very high temperature during the previous step by the explosion of the gaseous mix, the injected water vaporizes instantaneously, becoming very high-pressure steam. This pressure contributes to pushing piston  12  downwards (on the figure) in the cylinder and generating a high driving torque of flywheel  15 . 
         [0048]    Thanks to the combined thrusts due to the explosion of the mix of gaseous dihydrogen and air or oxygen, combined with the expansion of the steam produced in cylinder  11 , the flywheel  15  rotates, driving piston  12  first from the top dead centre (TDC) to the bottom dead centre (BDC), then beyond the bottom dead centre (BDC). A step for exhausting the gases contained in cylinder  11  starts while piston  12  “rises”. This step is represented by  FIG. 5 . The exhaust gases are exhausted through the exhaust valve  20  and the exhaust piping  20   a , as shown by arrow D. 
         [0049]    One will note that the engine  10  is of the two-stroke type, which makes it particularly efficient since, to every active step corresponding to the down move of piston  12  as a result of a thrust exerted on the head of said piston  12 , corresponds only one reactive phase corresponding to the up move of piston  12  and to the exhaust of the gases. 
         [0050]    Water electrolysis, in particular salt water and for example sea water, is used for generating a small volume of gaseous dihydrogen, since the greatest part of the pushing force is produced by the instantaneous vaporization of the water injected into the cylinder. Hence, an electrical generator, for example an alternator, of small dimensions is sufficient for producing the required electrical energy. In addition, the injection of the water has the secondary effect of cooling down the cylinder  11 , avoiding thus injecting the gaseous dihydrogen at a temperature exceeding its self-ignition temperature, which is of the order of 550° C. Since the temperature reached at the moment of the explosion of the gaseous mix is very high, one single water injection may not be sufficient to cool down the engine appropriately. In this case, a second, or even more cycles could be performed without explosion of the explosive gaseous mix, and the engine could operate as a simple steam engine. The steam is generated by the residual heat of the explosion of the gaseous mix and the controlled injection of water at the top of the cylinder at each beginning of a cycle. To that purpose, suitable temperature and pressure sensors are arranged to supply the information to a central control unit, which drives the injectors and the valves. 
         [0051]    Even though the engine  10  described comprises one single cylinder  11 , the internal combustion engine of the invention may be provided with several cylinders mounted in parallel and having similar operating modes. In this case, the engine  10  would be provided with a crankshaft coupled with the different rods of the different pistons. The operating phases of each of the pistons, of each of the cylinders, are identical in this case. However, the different pistons are shifted with respect to each other and the operating steps are also shifted, in order to optimize the torques exerted on the crankshaft. 
         [0052]    Furthermore, the engine  10  as it is described may undergo various modifications and appear in various variants covered by the invention. One of the fundamental advantages of the engine of the invention lies in the fact that the gaseous dihydrogen, whose storage is usually considered as hazardous, is consumed directly at the moment of its production, which eliminates totally the risks inherent to the storage. The volume produced during the preliminary steps is practically consumed during the first steps of each operating cycle of the engine. The exhaust gases produced are steam and air. The operation is economical and non-polluting.