Patent Description:
Vehicles comprising a front wheel and two rear wheels, in particular driving wheels, are known. Said vehicles, commonly known under the trade name "APE" by Piaggio, are widely and satisfactorily employed for transporting things and people, said vehicles being provided for the purpose with a cabin (for the driver and any passengers) and a box for transporting goods, which is open or closed according to needs and/or circumstances, said box being positioned at the back with respect to said cabin (with reference to the driving direction). Said vehicles are started up by means of a powertrain which, also but not only for reasons of space, is installed in the rear part of the vehicle, below the box, in a substantially central position (with respect to the longitudinal vertical plane of symmetry of the vehicle). The powertrain comprises an (internal combustion) thermal engine and a drive system directly actuated by the thermal engine, through which the torque generated by the thermal engine is transferred to the two rear wheels of the vehicle. Conventionally, the drive system comprises a differential for transmitting the torque.

According to a first known embodiment, the thermal engine is cooled through an air cooling system. Said air cooling system comprises a cooling fan installed on the block containing the thermal engine, said fan being rotated by the same thermal engine (in particular, the fan usually being keyed onto the drive shaft). The air is conveyed with a given pressure against the head of the cylinder by means of the fan, where thereby the head of the cylinder yields to the flow of the air, part of the heat generated by the combustion.

An example of state-of-the-art vehicle is described in document <CIT>. The vehicle has a radiator arranged opposite a rear wheel in a state in which an air inlet surface and an air outlet surface of the radiator are directed in a longitudinal direction of the vehicle. A vehicle body comprises a rear part that covers from a top of a power unit comprising the radiator. The radiator is arranged in an inclined manner such that an external end of the radiator in a direction of width of the vehicle is positioned behind an internal end of the radiator in the width direction of the vehicle.

Although they may be appreciated due to construction simplicity, simple maintenance and immediate operations and curbed maintenance costs (as well as management simplicity), said air cooling vehicles however have drawbacks essentially resulting from that, for example under prolonged conditions of engine stress, the air cooling is not always capable of ensuring an adequate cooling of the engine.

In order to overcome the above drawbacks, and therefore to ensure an adequate and reliable cooling of the engine, alternative embodiments have been suggested according to which the cooling of the thermal engine is achieved by a liquid cooling system (for example, water with added liquid antifreeze). According to said solutions, the coolant is caused to circulate in defined channeling through the head and/or the cylinder, where therefore the heat generated by the combustion is yielded to the coolant. In particular, the coolant is conveyed, by means of tubes outside the engine, through a radiator in which it is cooled following a heat exchange with an airflow directed against the radiator and usually generated by means of a fan. Moreover, the circulation of the coolant is obtained by a circulating pump, usually directly actuated by the thermal engine through a mechanical coupling. Moreover, the cooling systems according to the known and most widely used and/or implemented solutions conventionally comprise a by-pass line provided for excluding the radiator if the temperature of the water close to the head of the cylinder is contained, or in any case below a predetermined value, the deflection of the coolant in the by-pass line being regulated or managed by means of a thermostat operatively installed on the head-cylinder of the thermal engine.

Moreover, it is worth noting that according to the known solutions and in order to optimize the yielding of heat by the liquid in the radiator to the airflow generated by the fan, the radiator is installed in position facing the fan. Finally, it is also worth noting that the liquid cooling systems of the known type also provide an expansion vessel communicating with the hydraulic circuit to compensate for the losses of load and therefore, ensure a given coolant flow rate.

However, although they ensure a more efficient, reliable and constant cooling of the thermal engine than that ensured by the air cooling systems, the above-summarized liquid cooling systems according to the known solutions also have drawbacks and/or disadvantages that the Applicant intends overcoming or at least minimizing by means of the present invention.

A first drawback relates to the design of the frame, and in general of the layout of the rear part of the vehicle, being currently affected by the type of cooling system provided. Indeed, the radiator and the expansion vessel in vehicles with a liquid-cooled engine are directly installed on the frame in positions adapted to perform the function thereof. This ensures that the overall volumes and means (mechanical connections, brackets, supports, etc., for example) required for positioning these components of the cooling system are considered during the design, in addition to what is required to install the liquid circulating pipes external to the engine, i.e. those connecting the radiator and the expansion vessel to the rest of the hydraulic circuit. The design of the frame and the layout of the vehicle are therefore affected by the type of cooling system intended to be installed, where practically the design of a corresponding frame and/or layout ad hoc is required for every cooling system, with apparent problems not only in terms of actual design, but also of organization of production and/or manufacturing flows.

Moreover, it is worth noting that the vibrations generated by the engine differ from those generated by the frame, therefore where the component parts of the cooling system are subjected both to the vibrations generated by the engine and to those generated by the frame, with apparent problems related to undesired disconnecting of tubes, mechanical stress, etc..

Therefore, it is the main object of the present invention to overcome or at least minimize the drawbacks encountered in the solutions according to the prior art briefly described above.

In particular, it is an object of the present invention to suggest a solution which allows to design the frame and the layout of a vehicle which is compatible with different cooling systems, or in other words, according to which different cooling systems may be installed on vehicles characterized by a common frame and/or layout.

Moreover, it is an object of the present invention to suggest a solution which allows the mechanical stress on the cooling system to be limited to the mechanical stress substantially generated by the vibrations of the engine alone.

According to the present invention, a motor vehicle as defined in independent claim <NUM> is provided.

The present invention derives from the general consideration according to which the problems detected in the solutions of the known type may be effectively overcome or at least reduced by installing the radiator, and preferably also the expansion vessel, on the engine body, in particular through suitable connection means. In other words, the idea at the basis of the present invention is that of incorporating the radiator and the expansion vessel in the "suspended mass" connected to the frame. This solution indeed allows the installation on the same vehicle (frame) of different engines and/or cooling systems, for example of an air-cooled engine and a liquid-cooled engine.

Moreover, the assembly of the vehicle is also considerably facilitated by the idea underlying the present invention, because the engine may be directly installed together with the cooling system. Simultaneously, the radiator, the expansion vessel and the external hydraulic tubes vibrate in the same manner as the engine because they are connected thereto. This reduces the risk of breakdowns and at least partially avoids oversizing the connections currently required to resist different vibrating manners.

According to an embodiment, said cooling system comprises an expansion vessel, where also said expansion vessel is integral with said powertrain so as to also form part of said mass suspended from said frame.

According to an embodiment, said expansion vessel comprises a lower metal part fastened to said powertrain and an upper plastic material part including an opening and a corresponding closing plug.

According to an embodiment, said expansion vessel is fastened to the head of said thermal engine.

According to an embodiment, said fan is arranged between said crankcase and said radiator.

According to an embodiment, said radiator is supported by a support element fastened to said crankcase.

According to an embodiment, said fan is keyed onto a rotating shaft which protrudes from said crankcase and is rotated by said thermal engine.

According to an embodiment, said rotating shaft coincides with the drive shaft of said thermal engine.

According to an embodiment, said support element is shaped so as to define an inner space in which said fan is at least partially accommodated.

According to an embodiment, said support element has a main opening on the wall opposite to said crankcase, where said radiator and said fan are arranged facing said opening.

According to an embodiment, said support element comprises a side wall which radially delimits said inner space and extends from said wall with said opening, where said side wall comprises a plurality of secondary openings adapted to allow the at least partial discharge of the airflow from said radiator.

According to an embodiment, said cooling system comprises a pump for circulating said coolant, where said pump is actuated by a rotating shaft which protrudes from said crankcase and is rotated by said thermal engine.

According to an embodiment, the rotating shaft for actuating said pump coincides with the drive shaft of said thermal engine.

According to an embodiment, with respect to said powertrain, said pump is positioned on the side opposite to that of said radiator.

According to an embodiment, said vehicle has a three-wheel type configuration with one front steering wheel and two rear wheels in line with each other, and comprises a cabin for transporting passengers and said box is for transporting goods and is positioned at the back with respect to said cabin, and wherein said powertrain is like a mass suspended from said frame in position below said box.

Possible further embodiments of the present invention are defined by the claims.

The present invention is further clarified by means of the description of the embodiments depicted in the drawings, in which:.

The same reference numerals and letters in the Figures identify the same elements or components.

A description of the embodiments of the present invention shown in the drawings is given below, the present invention moreover not being limited to the embodiments described below and/or shown in the drawings; in particular, the present invention being a particularly advantageous application in three-wheel vehicles with trim of the type of the known Piaggio vehicle referred to as "APE"; the embodiments of the present invention shown in the drawings are described and clarified below with particular reference to the possible applications thereof in vehicles of the aforesaid type, the possible applications of the present invention moreover not being limited to Piaggio vehicles referred to as "APE".

<FIG> shows the operating principles of a liquid cooling system of the known type.

As shown, the cooling water, possibly with added antifreeze and/or anti-corrosion liquids, is circulated through pump PC in the inner channeling of the head and cylinder (CT). The liquid is heated and crosses the radiator (RAD), where heat is yielded to the external air. When thermostat T detects a temperature of the engine below a predetermined threshold (cold engine), the flow of liquid is deflected along a by-pass line which cuts out the radiator (RAD). The deflection of the flow occurs through a thermostatic valve which is directly controlled by thermostat (T). The expansion vessel (VE) is connected to the inlet branch of the radiator (RAD). The expansion vessel (VE) contains liquid and air and serves the purpose both of compensating for the volume of liquid during evaporation, thus allowing the filling of the circuit and the air purge. As mentioned, the layout is of the known and/or conventional type.

Moreover, as shown in <FIG>, the ambient air, by means of a rotary fan (FAN), is induced to cross the radiator (COOLING RADIATOR), where the coolant in the radiator (RAD) yields heat to the air crossing it, and where the air, heated in outlet from the radiator (RAD), is deflected in direction of the powertrain (CYLINDER and CYLINDER HEAD) so as to create a heat exchange aiming to cool the same powertrain, in particular engine <NUM>, the temperature of which is in any case higher than the air heated by the radiator.

Reference numeral <NUM> in <FIG> identifies a vehicle including a front steering wheel <NUM>, rear driving wheels <NUM> arranged along a common rotation axis and spaced apart from each other according to a given wheelbase, a driving cabin for accommodating the driver and any passengers, and finally a box <NUM> for transporting goods and/or further passengers; in particular, according to the embodiment depicted, a rear seat <NUM> is positioned in box <NUM>, box <NUM> therefore being adapted to accommodate both goods and/or luggage (at the back with respect to seat <NUM>) and passengers (sitting on seat <NUM>).

Vehicle <NUM> therefore has a three-wheel shape in which the rear wheels are fixed with respect to the front axle, i.e. they do not roll with respect to it. Thereby, the vehicle and the corresponding box <NUM> allow to carry loads which keep a stable position on floor <NUM> even when the vehicle takes a corner.

Moreover, again as shown, box <NUM> is delimited at the bottom by a floor <NUM>, where vehicle <NUM> comprises a powertrain (described in greater detail below) accommodated below floor <NUM>, in particular suspended (hung) from floor <NUM> according to methods described in greater detail below.

The powertrain, identified in <FIG> by reference numeral <NUM>, particularly comprises a thermal engine <NUM>, a differential assembly <NUM>, a clutch <NUM> and a gearshift (not identified by any reference numeral), where the differential assembly <NUM>, the clutch <NUM> and the gearshift form part of the drive system by means of which the torque generated by engine <NUM> is transmitted to the driving wheels <NUM>. For this purpose, differential <NUM> is positioned between the driving wheels <NUM>, in mechanical connection with both right-hand and left-hand differential shafts.

The methods for transmitting the torque generated by engine <NUM> to the driving wheels <NUM> are substantially of the known type and therefore a detailed description thereof is omitted due to synthesis reasons.

The thermal engine <NUM> and the drive system or assembly are accommodated in a crankcase defined by two mutually fastened half-shells <NUM>, also in this case according to substantially known methods and therefore not described in detail due to synthesis reasons.

With regard to the liquid cooling system, as depicted in the Figures, the same comprises a radiator <NUM> (with the classic "honeycomb" shape in the embodiment shown), a pump <NUM> for circulating the coolant, an expansion vessel <NUM> with a corresponding plug <NUM> thereof, where pump <NUM> is connected to radiator <NUM> by a first return tube <NUM> (from radiator <NUM> towards pump <NUM>), while a second delivery tube <NUM> is between the pump and the hydraulic circuit (CT) defined in engine <NUM>. A third tube <NUM> is designated to hydraulically connect the expansion vessel <NUM> to radiator <NUM>, while a further tube <NUM> is designated to connect, together with the first tube <NUM>, the outlet of radiator <NUM> to pump <NUM>. A by-pass tube <NUM> is also provided for bypassing radiator <NUM> when the temperature is not the operating temperature. Finally, another return tube 309A towards pump <NUM> is identified.

A fan <NUM> is interposed between radiator <NUM> and the engine assembly, fan <NUM> being keyed in particular onto a rotating shaft <NUM> which extends from the drive shaft of the thermal engine <NUM>, where the action of the engine results in fan <NUM> being rotated.

Moreover, as diagrammatically shown in <FIG>, the rotation of fan <NUM> results in the generation of an airflow (indicated by the arrows F1) from the space in front of the radiator through radiator <NUM>, where the heat of the coolant in the radiator thereby is yielded to the air through radiator <NUM>, and where the airflow outlet from radiator <NUM> (indicated by the arrows F2) is preferably deflected in direction of the engine assembly.

According to the present invention, a substantially vase-shaped support element <NUM> is used for this purpose, where a first open end portion <NUM> of support <NUM> is fastened to the engine assembly (in particular, to the containment crankcase <NUM>), while radiator <NUM> is fastened on the second open end portion <NUM> of support <NUM>, in particular by means of the connecting brackets <NUM> (shown in particular in <FIG> and <FIG>).

In order to protect radiator <NUM> and the connecting brackets <NUM>, there is provided a cover mask <NUM> including a plurality of flaps (deflectors) <NUM> by means of which the air is conveyed from the space in front of radiator <NUM> against radiator <NUM> itself. The second end portion <NUM> of the support element <NUM> defines a housing space <NUM> inside of which fan <NUM> is positioned. This comprises a plurality of blades <NUM> which extend from a bottom <NUM>.

Moreover, a further housing space <NUM> is defined downstream of bottom <NUM> of the bottom of fan <NUM> (with respect to the direction of the airflow generated by the rotation of fan <NUM>, see the arrows F1 and F2), and therefore between cover <NUM> and the end portion <NUM> of support <NUM>, in which further housing space there is accommodated an electric generator <NUM>, the stator of which is coaxial to shaft <NUM> and the rotor of which is keyed onto shaft <NUM>.

It is apparent from the above description that fan <NUM> is axial-centrifugal, where the definition "axial-centrifugal" means a condition where fan <NUM> axially sucks air (from the space in front of radiator <NUM>, see the arrows F1) and radially discharges (in a centrifugal manner, see the arrows F2).

For this purpose, the end portion <NUM> of support <NUM> upstream of cover <NUM> has a plurality of slits or openings (<NUM>) through which the air outlet from radiator <NUM> is radially deflected. For this purpose, the slits <NUM> are made at predefined portions of the end portion <NUM>. In particular, according to an embodiment, there are no slits <NUM> in the lower portion (facing downwards) of end <NUM>, rather in the upper portion (facing upwards) with an underlying angle of about <NUM>° (with vertex on the rotation axis of fan <NUM>), in particular in order to avoid the deflection of the air towards the ground because when vehicle <NUM> is used in the presence of dust and/or debris (unpaved roads, for example), the dust raised by the airflow could compromise or at least penalize the functionality of the engine due, for example to the too frequent clogging of the air filter, or also of radiator <NUM>, as a consequence of the accumulation of dust and/or debris in the honeycomb.

The slits <NUM> preferably are configured so as to deflect the air towards the powertrain, in particular towards engine <NUM>, in order to subtract heat from the same powertrain. In particular, the temperature in use of engine <NUM> is greater than that of the airflow processed by fan <NUM>, and therefore such an airflow may act as heat carrier for cooling engine <NUM>.

With reference again to <FIG> and further with reference to <FIG>, a description is given below of further details of the system consisting of powertrain - cooling system according to the present invention.

As shown, the expansion vessel <NUM> is fastened to the head <NUM> of engine <NUM> (<FIG>) in a higher position than radiator <NUM>, and in general in the highest position of the cooling circuit, to allow the filling thereof and the air purge. The expansion vessel <NUM> is mounted for the purpose to a metal support <NUM> mounted to the head of engine <NUM>. The metal support <NUM> particularly defines a surface on which a plastic containment vessel <NUM> rests, which contains the liquid which serves for the operation of the expansion vessel and therefore of the cooling circuit. An important aspect lies in that the metal support <NUM> is defined so as to carry the thermostatic valve (used to bypass the coolant according to the methods described above) indicated by <NUM> in <FIG>. As mentioned, said thermostatic valve indeed is controlled by the thermostat integrated therein and is opened and closed to circulate or not to circulate water through the radiator, according to the engine temperature.

Therefore, one of the concepts underlying the present invention has been shown, i.e., that according to which the expansion vessel <NUM> is made integral with the engine block so that it is also part of the mass suspended from the frame of the vehicle (together with all the tubes and channeling defining the cooling circuit). Moreover, according to a further aspect, the thermostatic valve <NUM> advantageously is integrated in the metal support <NUM>.

When the thermostatic valve opens, the circuit defined in the head <NUM> of engine <NUM> is made to communicate with the inlet branch of radiator <NUM> through the metal support <NUM>. The upper plastic part <NUM> always remains in communication with the lower part of the metal support <NUM>, which in turn communicates with the part of circuit which feeds radiator <NUM>.

The upper part <NUM> preferably is made of clear plastic also, but not only, to allow a reliable and constant (as well as immediate) check of the liquid level in the expansion vessel <NUM>. The upper part <NUM> is further provided with plug <NUM> for topping up the liquid. One of the main advantages of the embodiment described lies in that the cooling circuit may be directly filled in the production plant in which the assembly of the engine block takes place.

Moreover, the access to the expansion vessel <NUM> may be obtained by opening a suitable inspection door in a floor of the vehicle (of floor <NUM>, for example) in position above engine <NUM>.

The solution according to which the engine block is fastened to the frame of the vehicle is among the peculiarities of the present invention. In particular, as shown in <FIG> and <FIG>, the engine block is fastened to the frame of vehicle <NUM> by a first "T"-shaped anchoring element <NUM> including a first anchor bar anchored to the engine assembly, in particular to one of the half-shells <NUM> of the housing crankcase, and a second bar <NUM> which is transverse to said first bar <NUM>, at the opposite ends of which there are prepared a first shock absorbing pad <NUM> and a second shock absorbing pad <NUM>, respectively, which are made of elastic material such as rubber or the like, said first pad <NUM> and second pad <NUM> being intended to be anchored resting on a part forming the frame such as a cross member or the like (not shown), where the powertrain is suspended from the frame itself, with said first pad <NUM> and second pad <NUM> restrained to the frame.

Moreover, a further fastening and support element is identified in <FIG> by reference numeral <NUM> and comprises a bar <NUM> at an end of which there is fastened a bracket <NUM> which carries a shock absorbing pad <NUM>, said bracket being adapted to be fastened to a component of the frame, for example a support cross member (not shown).

Finally, it is worth noting that the powertrain comprises component parts common to powertrains with thermal engine of the known type which, although they have been described in detail, are to be considered as belonging to the powertrain of the vehicle according to the present invention.

The Figures indeed show component parts herein mentioned by way of example, such as a system for discharging combustion gases including a muffler <NUM>, and an air filter <NUM>, where further component parts not described and/or mentioned may in any case be recognized from the Figures by those skilled in the art.

Thus, it has been demonstrated by the previous detailed description of the non-limiting embodiments of the present invention, shown in the drawings, that the generality of the present invention allows the drawbacks encountered in the prior art to be overcome or at least minimized, and therefore the desired results to be achieved.

Indeed, as shown, the present invention allows to design the frame and the layout of a vehicle which is compatible with different cooling systems, or in other words, the installation of different cooling systems on vehicles characterized by a common frame and/or layout.

Moreover, the present invention allows the mechanical stress on the cooling system to be limited to the mechanical stress substantially generated by the vibrations alone of the engine, while contrarily, by means of the present invention, parts forming the cooling system such as the joining tubes <NUM>, <NUM>, <NUM> and <NUM> between radiator <NUM>, pump <NUM> and expansion vessel <NUM> are not subjected to mechanical stresses generated by the vibrations of the frame and/or vehicle <NUM> as a whole.

Although the present invention was clarified above by the description of the non-limiting embodiments thereof depicted in the drawings, the present invention is not limited to said non-limiting embodiments described above and shown in the drawings.

Claim 1:
A motor vehicle (<NUM>) comprising a front wheel (<NUM>), two rear wheels (<NUM>) arranged along a common rotation axis, a frame and a powertrain, wherein said powertrain comprises a thermal engine (<NUM>) and a mechanical transmission for transmitting the torque generated by said thermal engine (<NUM>) to at least one of said wheels (<NUM>, <NUM>), where said thermal engine (<NUM>) and said mechanical transmission are accommodated in a crankcase (<NUM>), and where said powertrain comprises a liquid cooling system including a radiator (<NUM>) and a fan (<NUM>) adapted to generate, by rotation, an airflow through said radiator (<NUM>), characterized in that said frame comprises a box (<NUM>) delimited at the bottom by a floor (<NUM>), in that said powertrain is connected to said floor (<NUM>) in a back part so as to be like a mass suspended from said floor (<NUM>), and in that said radiator (<NUM>) and said fan (<NUM>) are arranged on said powertrain so as to form part of said mass suspended from said frame.