Patent Description:
The present invention relates to a car provided with an internal combustion engine.

The present invention is advantageously applied to a car provided with an internal combustion engine powered with hydrogen, to which the following discussion will explicitly refer without thereby losing generality.

Hydrogen does not exist in the natural state on the earth because it is combined in molecules with other atoms (for example, water or hydrocarbons) and therefore, in order to have hydrogen, it is necessary to produce it by means of reforming or electrolysis consuming other energy (consequently, hydrogen is not an energy source but an energy vector).

The environmental impact of a car provided with an internal combustion engine powered with hydrogen is much lower than the environmental impact of a similar car provided with an internal combustion engine powered with a fossil fuel, as an internal combustion engine powered with hydrogen does not generate greenhouse gas (CO<NUM>) and generates very little CO, HC and fine particulate matter (generated due to a minimum quantity of lubricating oil which is burned in the combustion chambers).

Hydrogen has a reduced density (having a very simple molecule composed of only two hydrogen atoms) and therefore, in order to be able to store a suitable quantity (mass) of hydrogen, it is necessary to utilize very voluminous hydrogen tanks also when the maximum storage pressure of hydrogen reaches <NUM> bars (which currently represent a market standard). Besides, the hydrogen tanks are to be arranged in a position which is suitably protected against impacts from all directions and the hydrogen tanks have to preferably have a spherical shape or a cylindrical shape so as to be able to be resistant to the high internal pressure of hydrogen; these constraints further complicate the positioning of the hydrogen tanks in a car.

Consequently, a car provided with an internal combustion engine powered with hydrogen is longer and heavier (autonomy being equal) than a similar car provided with an internal combustion engine powered with gasoline and thus results definitely penalized in the dynamic performance.

Documents <CIT>, <CIT>, <CIT> and <CIT> describe an opposed-piston internal combustion engine.

The object of the present invention is to provide a car provided with an internal combustion engine powered with hydrogen which allows achieving a high performance (particularly in sports driving on track) without penalizing the autonomy.

According to the present invention, a car provided with an internal combustion engine powered with hydrogen is provided, in accordance with what is claimed by the appended claims.

The present invention will now be described with reference to the accompanying drawings, which illustrate some non-limiting example embodiments thereof, wherein:.

In <FIG>, reference numeral <NUM> indicates, as a whole, a hybrid car (i.e. having hybrid propulsion) provided with two front drive wheels <NUM> which receive the torque from an (at least one) electric machine <NUM> (schematically illustrated in <FIG>) and with two rear drive wheels <NUM> which receive the torque from an internal combustion engine <NUM> (schematically illustrated in <FIG>).

According to what is illustrated in <FIG>, the electric machine <NUM> is connected to the two front drive wheels <NUM> by means of a drive system (of known type and not illustrated) provided with a front differential; similarly, also the internal combustion engine <NUM> is connected to the two rear drive wheels <NUM> by means of a drive system <NUM> provided with a gearbox <NUM> and with a rear differential <NUM> (schematically illustrated in <FIG>).

Preferably, the electric machine <NUM> is reversible (i.e. it can operate both as electric motor absorbing electric energy and generating a mechanical torque, and as electric generator absorbing mechanical energy and generating electric energy); according to other embodiments not illustrated, the electric machine <NUM> is not provided (and therefore the car <NUM> is not hybrid).

According to what is illustrated in <FIG> and <FIG>, the car <NUM> comprises a passenger compartment <NUM> which is arranged between the two front wheels <NUM> and the two rear wheels <NUM> and contains on its inside a driving position (schematically illustrated in <FIG>) which is arranged on the left side (alternatively, it could also be arranged on the right side).

According to what is illustrated in <FIG> and <FIG>, the car <NUM> comprises a body <NUM> which delimits (among the other things) the passenger compartment <NUM> and has two sides in which at least two doors are obtained.

According to what is illustrated in <FIG>, the car <NUM> comprises a bottom <NUM> which constitutes the lowest part of the car <NUM> and in use faces a road surface on which the car <NUM> is moving.

According to a preferred embodiment, the internal combustion engine <NUM> is powered with hydrogen (or also another gaseous fuel). According to a different embodiment, the internal combustion engine <NUM> is powered with gasoline (or also another liquid fuel).

According to what is illustrated in <FIG>, the internal combustion engine <NUM> is powered with hydrogen which is stored at high pressure (for example, having a maximum pressure of approximately <NUM> bars) in six different tanks <NUM> which have a spherical shape and have the same dimension (but could also have different dimensions). In the alternative embodiment illustrated in <FIG>, three tanks <NUM> having a cylindrical shape and different dimensions (i.e. the central tank <NUM> is smaller than the two side tanks <NUM>) are present. According to other embodiments not illustrated, a different number of tanks <NUM> is provided which can all have the same shape (spherical, cylindrical or of other type) or also different shapes (for example, some tanks <NUM> could have a spherical shape, whereas other tanks could have a cylindrical shape). More in general, the single tank <NUM> or the several tanks <NUM> can have any shape which can also be different from the spherical shape or from the cylindrical shape.

The internal combustion engine <NUM> is arranged in a central or rear position, i.e. the internal combustion engine <NUM> is arranged behind the passenger compartment <NUM> and is located between the front wheels <NUM> and the rear wheels <NUM> (central arrangement as is illustrated in the accompanying figures) or is located beyond the rear wheels <NUM> (rear arrangement not illustrated). Furthermore, as is better illustrated in <FIG>, the internal combustion engine <NUM> has a "sole" shape, i.e. a shape that is longitudinally and transversely wide and vertically very contained. The drive system <NUM> is arranged immediately behind the internal combustion engine <NUM> (i.e. is arranged at the back with respect to the internal combustion engine <NUM> and is located at the same vertical level of the internal combustion engine <NUM>).

As is better illustrated in <FIG>, the tanks <NUM> are arranged above the internal combustion engine <NUM> and above the drive system <NUM>; i.e. each tank <NUM> is arranged above the internal combustion engine <NUM> and/or above the drive system <NUM>. In other words, the tanks <NUM> are arranged (approximately) at the same vertical level and are located above the internal combustion engine <NUM> and above the drive system <NUM>.

According to what is illustrated in <FIG>, <FIG> and <FIG>, the internal combustion engine <NUM> is an opposed-piston two-stroke internal combustion engine and the number of pistons <NUM> is twice the number of the cylinders <NUM> obtained in the crankcase <NUM> as two opposed pistons <NUM> slide in each cylinder <NUM> (in particular, three or six cylinders <NUM> and six or twelve pistons <NUM> are provided). The internal combustion engine <NUM> comprises two crankshafts <NUM> which are positioned at the two ends of the crankcase <NUM>; each crankshaft <NUM> is connected by means of respective connecting rods to three pistons <NUM> arranged on the same side of the crankshaft <NUM>.

The two crankshafts <NUM> are connected to one another by means of a gear transmission <NUM> (better illustrated in <FIG>) so that the two crankshafts <NUM> always rotate in a synchronized manner; in the (non-limiting) example illustrated in <FIG>, the gear transmission <NUM> comprises two lateral toothed wheels <NUM>, each integral with a corresponding crankshaft <NUM>, and one single central toothed wheel <NUM> which is hinged idle to the crankcase <NUM> and meshes with both lateral toothed wheels <NUM> (according to other embodiments, two, three or four central toothed wheels <NUM> could be provided). The connection of the two crankshafts <NUM> made by the gear transmission <NUM> causes the motion of the pistons <NUM> of a crankshaft <NUM> to always correspond to an identical motion of the pistons <NUM> of the other crankshaft <NUM>, but in opposite direction. Two coupled pistons <NUM> (i.e. arranged in the same cylinder <NUM>) move away from one another in the expansion phase and move close to one another in the compression phase; i.e. it is as if the stroke is divided between the two pistons <NUM> and this enables adopting the high stroke/bore ratios necessary for a two-stroke engine without reaching too high average velocity values of the piston <NUM>.

In the internal combustion engine <NUM> a head is not present, since a piston <NUM> acts as head for the other piston <NUM>. Therefore, the engine block of the internal combustion engine <NUM> is only composed of the crankcase <NUM>.

In the internal combustion engine <NUM> neither suction valves nor the exhaust valves are present, the function of which is carried out by suction ports <NUM> and exhaust ports <NUM> (illustrated in <FIG>) which are opened and closed (as it occurs in the two-stroke engines) by the alternative movement of the pistons <NUM>.

According to what is illustrated in <FIG>, in each cylinder <NUM> two diametrically opposed fuel injectors <NUM> are provided which are arranged in the centre of the cylinder <NUM> and perform a direct injection of the fuel into the cylinder <NUM>; according to other embodiments not illustrated, the number and/or the arrangement of the fuel injectors <NUM> are different. <FIG> illustrates a direct fuel injection into the cylinders <NUM> but the fuel injection into the cylinders <NUM> could also be (partially or completely) indirect.

In each cylinder <NUM> two diametrically opposed spark plugs <NUM> are provided which are arranged in the centre of the cylinder <NUM> and are cyclically activated for triggering the ignition of the mixture of air (comburent) and fuel present in the combustion chamber at the end of the compression phase; according to other embodiments not illustrated, the number and/or the arrangement of the spark plugs <NUM> are different.

According to what is illustrated in <FIG>, the internal combustion engine <NUM> comprises a suction system which draws air from the external environment for conveying the air into the cylinders <NUM> (the inlet of the air in the cylinders <NUM> occurs through the suction ports <NUM>). The suction system comprises a suction duct <NUM> which ends in a suction manifold <NUM> which is directly connected to all the cylinders <NUM>; the inlet of air in the suction manifold <NUM> is adjusted by a throttle valve.

According to what is illustrated in <FIG>, the internal combustion engine <NUM> comprises an exhaust system which releases the exhaust gases coming from the cylinders <NUM> into the external environment. The exhaust system comprises an exhaust duct <NUM> which originates from the exhaust ports <NUM> and is provided with an (at least one) exhaust gas treatment device <NUM> (typically a catalyst).

According to what is illustrated in <FIG>, a turbocharger <NUM> is provided which increases the volumetric efficiency (filling) of the cylinders <NUM> and consequently an intercooler <NUM> is arranged along the suction duct <NUM>.

According to what is illustrated in <FIG>, each crankshaft <NUM> is longitudinally oriented (i.e. parallel to the motion direction), projects out of the crankcase <NUM> at the back (i.e. through the rear wall), and is connected to the corresponding lateral toothed wheel <NUM> of the gear transmission <NUM>; downstream of the lateral toothed wheel <NUM>, each crankshaft <NUM> is connected to a flywheel <NUM> (preferably a dual-mass flywheel).

According to what is illustrated in <FIG>, the gearbox <NUM> is arranged immediately behind the internal combustion engine <NUM> and is a dual-clutch gearbox. Therefore, the gearbox <NUM> comprises two clutches <NUM>, each directly connected to a corresponding crankshaft <NUM> downstream of the respective flywheel <NUM>; i.e. each crankshaft <NUM> ends at the inlet of a corresponding clutch <NUM> which is located after the respective flywheel <NUM>. Consequently, the two clutches <NUM> are separate and far from one another. The gearbox <NUM> comprises two input shafts <NUM> which are coaxial to one another and face one another head-to-head (i.e. are not inserted inside one another) and are transversely oriented (i.e. perpendicular to the motion direction). Each input shaft <NUM> is connected to a respective clutch <NUM> through a bevel gear <NUM> which transforms the rotation around a longitudinal axis of rotation (coming from a crankshaft <NUM> arranged longitudinally through a clutch <NUM>) into a rotation around a transverse axis of rotation (to be transmitted to an input shaft <NUM> arranged transversely).

The gearbox <NUM> comprises one single output shaft <NUM> connected to the differential <NUM> which transmits the motion to the rear drive wheels <NUM>; according to an alternative and equivalent embodiment, the dual-clutch gearbox <NUM> comprises two output shafts <NUM> both connected to the differential <NUM>. From the differential <NUM> a pair of axle shafts <NUM> depart (schematically illustrated in <FIG> and <FIG>), each integral with a rear drive wheel <NUM>.

The gearbox <NUM> has seven forward gear ratios indicated by Roman numerals (first gear ratio I, second gear ratio II, third gear ratio III, fourth gear ratio IV, fifth gear ratio V, sixth gear ratio VI and seventh gear ratio VII) and a reverse gear (indicated by the letter R). Each input shaft <NUM> and the output shaft <NUM> are mechanically coupled to one another by means of a plurality of gears, each defines a respective gear ratio and comprises a primary toothed wheel <NUM> mounted on the input shaft <NUM> and a secondary toothed wheel <NUM> mounted on the output shaft <NUM>. In order to allow the correct operation of the gearbox <NUM>, all the odd gear ratios (first gear ratio I, third gear ratio III, fifth gear ratio V, seventh gear ratio VII) are coupled to a same input shaft <NUM>, whereas all the even gear ratios (second gear ratio II, fourth gear ratio IV, and sixth gear ratio VI) are coupled to the other input shaft <NUM>.

Each primary toothed wheel <NUM> is splined to a respective input shaft <NUM> for rotating always integral with the input shaft <NUM> and permanently meshes with the respective secondary toothed wheel <NUM>; whereas, each secondary toothed wheel <NUM> is mounted idle on the output shaft <NUM>. Furthermore, the gearbox <NUM> comprises four double synchronizers <NUM>, each mounted coaxial to the output shaft <NUM>, arranged between two secondary toothed wheels <NUM>, and adapted to be actuated for alternatively engaging the two respective secondary toothed wheels <NUM> to the output shaft <NUM> (i.e. for alternatively making the two respective secondary toothed wheels <NUM> angularly integral with the output shaft <NUM>). In other words, each synchronizer <NUM> can be shifted in a direction for engaging a secondary toothed wheel <NUM> with the output shaft <NUM>, or can be shifted in the other direction for engaging the other secondary toothed wheel <NUM> with the output shaft <NUM>.

According to a different embodiment not illustrated, the primary toothed wheels <NUM> are mounted idle on the respective input shafts <NUM>, the synchronizers <NUM> are coupled to the primary toothed wheels <NUM>, and the secondary toothed wheels <NUM> are splined to the output shaft <NUM> for always rotating integral with the output shaft <NUM>.

The differential <NUM> receives the motion from the output shaft <NUM> of the gearbox <NUM> through an output toothed wheel <NUM> integral with the output shaft <NUM>, is devoid of bevel gear (being the output shaft <NUM> already arranged transversely) and transmits the motion to the two rear drive wheels <NUM> by means of the two respective axle shafts <NUM>. Preferably and according to what is illustrated in <FIG>, the differential <NUM> is arranged above the gearbox <NUM>, i.e. above the shafts <NUM> and <NUM> of the gearbox <NUM>.

In the embodiment illustrated in the accompanying figures, each clutch <NUM> is coaxial to the corresponding (longitudinally oriented) crankshaft <NUM> and is directly connected to an end of the corresponding crankshaft <NUM>; consequently, between each clutch <NUM> and the corresponding (transversely oriented) input shaft <NUM> there is interposed a bevel gear <NUM>. According to a different embodiment not illustrated, each clutch <NUM> is coaxial to the corresponding (transversely oriented) input shaft <NUM> and is directly connected to an end of the corresponding input shaft <NUM>; consequently, between each clutch <NUM> and the corresponding (longitudinally oriented) crankshaft <NUM> there is interposed a bevel gear <NUM>.

According to what is illustrated in <FIG> and <FIG>, each crankshaft <NUM> projects out of the crankcase <NUM> also on the opposite side relative to the gearbox <NUM>, i.e. projects out of the crankcase <NUM> at the front (i.e. through a front wall opposite the rear wall). The front end of a crankshaft <NUM> (which projects out of the crankcase <NUM>) is connected to an alternator <NUM> (i.e. to an electric energy generator) by means of a drive <NUM> (preferably a belt drive); in this embodiment, the alternator <NUM> is arranged beside the crankcase <NUM>. According to a different embodiment not illustrated, the alternator <NUM> is coaxial to the respective crankshaft <NUM> and is directly head-to-head connected to the crankshaft <NUM> without the need for the drive <NUM>; in this embodiment, the alternator <NUM> is arranged in front of the crankcase <NUM>. The front end of the other crankshaft <NUM> (which projects out of the crankcase <NUM>) is connected to a compressor <NUM> (which is part of an air conditioning system) by means of a drive <NUM> (preferably a belt drive); in this embodiment, the compressor <NUM> is arranged beside the crankcase <NUM>. According to a different embodiment not illustrated, the compressor <NUM> is coaxial to the respective crankshaft <NUM> and is directly head-to-head connected to the crankshaft <NUM> without the need for the drive <NUM>; in this embodiment, the compressor <NUM> is arranged in front of the crankcase <NUM>.

According to what is illustrated in <FIG>, a starter motor <NUM> is provided which is utilized for starting the internal combustion engine <NUM> and is connected to the gear transmission <NUM>; i.e. a shaft of the starter motor <NUM> is provided with a toothed wheel which meshes with one of the toothed wheels <NUM> and <NUM> of the gear transmission <NUM>. In particular, in the embodiment illustrated in the accompanying figures, the starter motor <NUM> is connected to the central toothed wheel <NUM> of the gear transmission <NUM>.

In the variation illustrated in <FIG>, the gear transmission <NUM> comprises two lateral toothed wheels <NUM>, each integral with a corresponding crankshaft <NUM>, and two twin central toothed wheels <NUM> which are hinged idle to the crankcase <NUM>, each laterally mesh with a respective lateral toothed wheel <NUM>, and centrally mesh with one another.

According to a different embodiment not illustrated, one single reversible electric machine is provided which carries out both the function of alternator (being made to operate as electric generator), and the function of starter motor (being made to operate as electric motor); the single reversible electric machine can be connected to a crankshaft <NUM> (in place of the alternator <NUM>) or can be connected to the gear transmission <NUM> (in place of the starter motor <NUM>).

According to what is illustrated in <FIG> and <FIG>, the car <NUM> comprises a rear aerodynamic diffuser <NUM> which faces the road surface, starts in the area of a rear wall of the crankcase <NUM> of the internal combustion engine <NUM> and is (partially) arranged under the gearbox <NUM>.

According to what is illustrated in <FIG>, inside a chassis of the car <NUM> an engine compartment <NUM> is obtained in which the internal combustion engine <NUM> is arranged. According to what is illustrated in <FIG>, the bottom <NUM> of the car <NUM> comprises an opening <NUM> which is arranged in the area of the engine compartment <NUM> and a removable panel <NUM> which is fixed in a removable manner and closes the opening <NUM>. The opening <NUM> has a dimension similar to a dimension of the engine compartment <NUM>; i.e. the dimension of the opening <NUM> is approximately (as much as possible) identical to the dimension of the engine compartment <NUM> so that through the opening <NUM> there can be a complete access to the engine compartment <NUM>.

According to a preferred embodiment, the removable panel <NUM> is at least partially transparent; in particular, the removable panel <NUM> centrally has a transparent window <NUM> (for example made of glass). The function of the transparent window <NUM> is essentially technical as it allows visibly inspecting the internal combustion engine <NUM> without having to remove the removable panel <NUM>.

According to a preferred embodiment, the body <NUM> has no openable hood (arranged above the engine compartment <NUM>) which allows access to the engine compartment <NUM>; i.e. the access to the engine compartment <NUM> occurs only from below through the opening <NUM> as the upper part of the engine compartment <NUM> is permanently closed by fixed non-removable panels of the body <NUM>. To such regard, it is important to observe that a top access to the engine compartment <NUM> would be anyway very difficult as it would require to remove the tanks <NUM>.

According to a preferred embodiment, the removable panel <NUM> is directly fixed to the chassis <NUM> by means of a plurality of screws <NUM> (preferably quarter-turn screws <NUM>).

The rear aerodynamic diffuser <NUM> faces the road surface, is arranged behind the removable panel <NUM>, and borders with the removable panel <NUM>. Namely, the rear aerodynamic diffuser <NUM> starts where the removable panel <NUM> ends. Also the aerodynamic diffuser <NUM> is removable for allowing a simpler access to the gearbox <NUM>.

The embodiments described herein can be combined with one another within the scope of the appended claims.

The above-described car <NUM> has numerous advantages.

Firstly, the above-described car <NUM> allows simultaneously combining a large hydrogen storage capacity (being thus able to offer a satisfactory autonomy) with a very high dynamic performance thanks to a wheelbase, an overall weight, and a weight distribution which are optimal. These results are obtained thanks to the particular conformation and arrangement of the internal combustion engine <NUM> and of the drive system <NUM> which allow creating a substantial free space for housing the hydrogen tanks <NUM> without penalizing the dynamic performance of the car <NUM>. In fact, the internal combustion engine <NUM> and the drive system <NUM> are completely located in a central position (i.e. between the front wheels <NUM> and the rear wheels <NUM>) and are arranged very low; consequently, the centre of gravity of the car <NUM> is perfectly central and is arranged low enabling obtaining an optimal dynamic behaviour of the car <NUM>. To such regard, it is important to note that the tanks <NUM> are arranged above, but despite being very bulky they have, on the whole, a reduced weight (also when they are full).

The above-described car <NUM> allows providing a rear aerodynamic extractor (diffuser) having extremely large dimensions thus allowing the generation of a very high aerodynamic load without any penalization of the drag. Namely, in the above-described car <NUM>, the aerodynamic diffuser <NUM> has a very large dimension (it thus allows generating a high aerodynamic load for a modest increase in the drag) even if the internal combustion engine <NUM> is placed in a central/rear position (thus having an optimal mass distribution between the front axle and the rear axle) and, simultaneously, the wheelbase is relatively short (i.e. the car <NUM> has an extremely performing dynamic behaviour).

In the above-described car <NUM>, also thanks to the particular conformation of the dual-clutch gearbox <NUM> which is transversely arranged immediately behind the internal combustion engine <NUM>, it is possible to obtain a particularly favourable (i.e. compact despite being very functional) location of all the elements of the powertrain system for minimizing the wheelbase length (i.e. the distance between the front axle and the rear axle).

In the above-described car <NUM>, the accessibility to all the zones of the internal combustion engine <NUM> is optimal and complete; this result is obtained thanks to the accessibility from the bottom which, once lifted the car <NUM>, always allows an operator to arrange himself/herself exactly under the component on which to intervene. Namely, the accessibility from the bottom to the internal combustion engine <NUM> makes the maintenance easy and simple, as the operators are not limited by the shape of the car <NUM> but can easily move in all the zones of the internal combustion engine <NUM> being the car <NUM> lifted.

In the above-described car <NUM>, the fact that the removable panel is at least partially transparent constitutes, besides an undoubtful technical advantage as explained in the foregoing, an aesthetic innovation and makes the removable panel also an aesthetic element; it is important to note that thanks to the aerodynamic diffuser <NUM> of great dimensions, it is relatively easy to see through the transparent wall of the removable panel at least part of the internal combustion engine <NUM> without having to exceedingly bend.

Claim 1:
A car (<NUM>) comprising:
two front wheels (<NUM>);
two rear wheels (<NUM>);
an opposed-piston internal combustion engine (<NUM>) comprising: a crankcase (<NUM>), a number of cylinders (<NUM>) obtained in the crankcase (<NUM>), a number of pistons (<NUM>) twice the number of the cylinders (<NUM>) as two opposed pistons (<NUM>) slide in each cylinder (<NUM>), and two crankshafts (<NUM>), which are longitudinally oriented and are each connected to a respective half of the pistons (<NUM>) arranged on a same side of the crankcase (<NUM>); and
a gearbox (<NUM>), which is connected to the crankshafts (<NUM>) of the internal combustion engine (<NUM>) and is arranged behind the internal combustion engine (<NUM>);
the car (<NUM>) is characterized in that the gearbox (<NUM>) comprises:
two clutches (<NUM>), each separate and far from the other clutch (<NUM>) and connected to a corresponding crankshaft (<NUM>); and
two input shafts (<NUM>), each connected to a respective clutch (<NUM>).