Patent Description:
Electric motor vehicles comprise, in a known manner:.

Said motor vehicles further comprise one or more electric batteries designed to power the electric machine with the necessary quantity of electric power.

The range of electric motor vehicles is determined by the quantity of electrical energy than can stored per volume unit in the batteries.

In the state of the art, said value approximately is one tenth of the quantity of energy that can be stored per volume unit through the use of a fossil fuel.

This sets limits to the performances of electric motor vehicles, especially when they are used on tracks or for professional races.

Indeed, as it is known, when driving along a bend, motor vehicles counter centrifugal force through the friction of the tyres against the ground in a radial direction relative to the arc described by the bend.

As a consequence, for a given radius of the bend, the square of the maximum travelling speed of a motor vehicle in conditions of grip is proportional to the vertical load acting upon the tyres.

In order to increase said load up to values exceeding the weight of the motor vehicle, motor vehicles are provided with downforce aerodynamic surfaces, namely shaped so as to generate an additional vertical downward thrust. Said vertical downward thrust, known as "downforce", is proportional to the square of the driving speed of the motor vehicle and to a downforce coefficient associated with the shape of the aerodynamic surface.

The increase in said downforce inevitably leads to an increase in the aerodynamic resistance of the motor vehicle.

This is due to the fact that the downforce coefficient of the aerodynamic surface increases as the resistance coefficient increases.

Because of this increase in aerodynamic resistance, electric motors must deliver a greater electric power in order to maintain desired speed values on straight stretches of road.

Said electric power increase further jeopardizes the range of the motor vehicle.

Therefore, in order to increase the range of the motor vehicle, thus enabling an acceptable sports use, the aerodynamic resistance of the motor vehicle should be reduced as much as possible, without jeopardizing the overall weight acting upon the wheels.

In other words, the overall resistance coefficient of the motor vehicle should be reduced, though without affecting the downforce coefficient of the aerodynamic surfaces.

As it is known, said resistance coefficient is determined, to a significant extent, by the layout of the rear portion of the motor vehicle, namely by the dimensions of the motor vehicle along a transverse dimension, which is orthogonal to a normal forward driving direction of the motor vehicle.

Axles are known, for example from <CIT>, which comprise a pair of electric machines operatively connected to respective wheels and comprising respective output shafts arranged parallel to the transverse direction of the motor vehicle.

The dimensions of said electric machines determine a lower limit for the maximum front section of the motor vehicle in the rear portion and, hence, a lower limit for the overall resistance coefficient and for the resulting energy consumptions of the motor vehicle.

In the automotive industry, an electric axle for a motor vehicle is needed, which reduces energy consumptions, though preserving a high aerodynamic load, so as to significantly increase the range of the motor vehicle, especially in racing mode.

Furthermore, the overall inertia of the motor vehicle needs to be reduced, with a consequent improvement in the dynamic performances of the motor vehicle.

<CIT>, <CIT>, <CIT>, <CIT> and <CIT> disclose a motor vehicle according to the preamble of claim <NUM>.

The object of the invention is to provide an axle, which is capable of fulfilling at least one of the needs discussed above.

The aforesaid object is reached by the invention, as it relates to a motor vehicle as defined in claim <NUM>.

The invention will be best understood upon perusal of the following detailed description of a preferred embodiment, which is provided by way of non-limiting example, with reference to the accompanying drawings, wherein:.

With reference to <FIG>, number <NUM> indicates a motor vehicle comprising a body <NUM> defining a passenger compartment <NUM>.

The motor vehicle <NUM> is a top-of-the-range motor vehicle designed both for a conventional urban/suburban use and for a racing track use.

Furthermore, the motor vehicle <NUM> is a hybrid or electric vehicle and is provided with electric batteries <NUM>.

Hereinafter, expressions such as "above", "under", "in front of", "behind" and others similar to them are used with reference to normal driving conditions of the motor vehicle <NUM>.

The axes X, Y define a horizontal plane P integral to the body <NUM> and arranged, in use, substantially horizontal.

The axes X, Z define a vertical plane Q integral to the body <NUM> and arranged, in use, substantially vertical.

For the purposes of the following disclosure, the plane Q is a longitudinal middle plane of the motor vehicle <NUM>.

The body <NUM> defines a front <NUM> and a rear <NUM>, with reference to a normal forward driving direction parallel to the axis X.

The motor vehicle <NUM> further comprises:.

Hence, the motor vehicle <NUM> comprises:.

Each front and rear suspension <NUM>, <NUM> comprises, extremely in short, an elastic element <NUM> and a damping element <NUM> interposed between the respective front wheels <NUM>, <NUM> (rear wheels <NUM>, <NUM>) and the body <NUM>.

Each front suspension and rear suspension <NUM>, <NUM> allows the front wheels <NUM>, <NUM> (rear wheels <NUM>, <NUM>) to move, in a known manner, relative to the body <NUM>, following the irregularities of the ground according to an approximately vertical trajectory, hence parallel to the axis Z.

Consequently, the axes A, B (C, D) of the front wheels <NUM>, <NUM> (rear wheels <NUM>, <NUM>) always remain approximately parallel to the axis Y of the body <NUM>.

The output shafts <NUM>, <NUM> can advantageously rotate around respective axes X1, X2 orthogonal relative to the axes C, D and extend from the side of the rear <NUM>, with reference to the axes C, D.

More in detail, the axes X1, X2 are parallel to one another and to a common axis K.

The axis K lies on the plane Q of the motor vehicle <NUM>.

The axis K defines, with the axis X, an angle α oriented towards the front <NUM> and ranging from <NUM> to <NUM> degrees (<FIG>).

The angle α is, in the specific case shown herein, five degrees.

Each assembly <NUM>, <NUM> further comprises (<FIG>):.

The brakes <NUM>, <NUM> are, in the specific case shown herein, disc brakes.

The brakes <NUM>, <NUM> can be operated independently of one another so as to exert respective braking torques, which are independent of one another, upon the respective wheels <NUM>, <NUM>.

Each brake <NUM>, <NUM> is located at an axial end of the relative electric motor <NUM>, <NUM> opposite the axis C, D of the relative wheel <NUM>, <NUM>.

The electric motors <NUM>, <NUM> are accommodated in the compartment <NUM> and the respective brakes <NUM>, <NUM> face the cross member <NUM>.

Each assembly <NUM>, <NUM> has a length L1 parallel to the axis K, which is greater than a width L2 parallel to the axis Y (<FIG>).

The motor vehicle <NUM> further comprises a casing <NUM> accommodating both motors <NUM>, <NUM> and the relative transmission assemblies <NUM>.

In particular, the casing <NUM> serves as stator for the electric motors <NUM>, <NUM>.

The casing <NUM> has a length L3 parallel to the axes X1, X2 and a width L4 parallel to the axes X1, X2. The length L3 is greater than the length L4 (<FIG>).

Each casing <NUM> consists of a pair of half-shells <NUM>, <NUM> shown in <FIG>.

The motors <NUM>, <NUM> can be operated independently of one another, so as to exert respective drive torques, which can be adjusted independently of one another, upon the rear wheels <NUM>, <NUM>.

The motor vehicle <NUM> further comprises an additional braking system (not shown) configured to exert a plurality of further braking torques upon the respective front wheels <NUM>, <NUM> and rear wheels <NUM>, <NUM>.

The aforesaid braking system could be of the traditional kind, namely acting through "friction".

In use, the electric motors <NUM>, <NUM> are powered by the electric batteries <NUM> and are operated independently of one another so as to generate respective drive torques acting upon the rear wheels <NUM>, <NUM> by means of the corresponding transmission assemblies <NUM>, <NUM>, so as to cause the motor vehicle <NUM> to move forward.

The brakes <NUM>, <NUM> can be operated by the driver in order to brake the electric motors <NUM>, <NUM> and exert, by so doing, respective braking torques upon the rear wheels <NUM>, <NUM>.

The disclosure above reveals evident advantages that can be reached with the invention.

In particular, the electric motors <NUM>, <NUM> extend from the side of the rear <NUM> of the body <NUM> relative to the axes C, D and the output shafts <NUM>, <NUM> can rotate around respective axes X1, X2 orthogonal to the axes C, D of the corresponding rear wheels <NUM>, <NUM>.

In this way, the electric motors <NUM>, <NUM> are side by side and are parallel to the axis K of the motor vehicle <NUM>.

This reduces the overall dimensions of the motor vehicle <NUM> parallel to the axis Y in the region of the axle <NUM>, namely at the rear <NUM> of the body <NUM>.

This reduction of dimensions allows the body <NUM> - in particular the rear <NUM> - to be shaped according to a more aerodynamic layout compared to known solutions discussed in the introduction to the description.

By so doing, the overall resistance coefficient of the motor vehicle <NUM> can be reduced, though without affecting the downforce coefficient of the motor vehicle <NUM>.

Therefore, consumptions are reduced and, hence, the range of the motor vehicle <NUM> increases, preserving at the same time the ability of the motor vehicle <NUM> to travel along curved trajectories at high speeds.

In short, the motor vehicle <NUM> ensures particularly high performances and can be used for races.

In addition, the arrangement of the electric motors <NUM>, <NUM> and of a large part of the respective assemblies <NUM>, <NUM> behind the axes C, D leaves the compartment <NUM> completely free for accommodating the electric batteries <NUM>.

Therefore, the electric power stored in the electric batteries <NUM> can be increased, with consequent further benefits for the range of the motor vehicle <NUM>.

It should be pointed out that said benefits are obtained without necessarily having to increase the wheel base of the motor vehicle <NUM>, namely the distance between the axes A, B of the front wheels <NUM>, <NUM> and the axes C, D of the rear wheels <NUM>, <NUM>.

The brakes <NUM>, <NUM> are located inside the compartment <NUM> and in a position facing the cross member <NUM> along the axis X.

In this way, in case of a rear hit that causes the cross member <NUM> to collapse, the brakes <NUM>, <NUM> protect the respective electric motors <NUM>, <NUM>, thus preserving the ability to move the motor vehicle <NUM>.

The assemblies <NUM>, <NUM> have a longitudinal length L1 parallel to the axis K, which is greater than transverse length L2 parallel to the axis Y.

Besides the advantages indicated above, this further reduces the overall inertia of the motor vehicle <NUM>, with a consequent improvement in the dynamic performances of the motor vehicle <NUM>.

Finally, the motor vehicle <NUM> according to the invention can be subjected to changes and variations, which, though, do not go beyond the scope of protection set forth in the appended claims.

Claim 1:
A motor vehicle (<NUM>) comprising:
- a body (<NUM>) defining a front (<NUM>) and a rear (<NUM>), with reference to a normal forward driving direction of the motor vehicle (<NUM>);
- a first axle (<NUM>) carried by said front (<NUM>) and comprising, in turn, a first and a second front wheel (<NUM>, <NUM>), which can rotate around a first and a second axis (A, B), respectively;
- a second axle (<NUM>) carried by said rear (<NUM>) and comprising, in turn, a third and a fourth rear wheel (<NUM>, <NUM>), which can rotate around a third and a fourth axis (C, D), respectively;
- at least one first electric motor (<NUM>, <NUM>) carried by said second axle (<NUM>); and
- a fifth longitudinal axis (X) parallel to said normal forward driving direction;
said first electric motor (<NUM>, <NUM>) comprising, in turn, a first output shaft (<NUM>, <NUM>), which can rotate around a sixth axis (X1, X2) orthogonal to said third and fourth axis (C, D);
said first electric motor (<NUM>, <NUM>) extending from the side of said rear (<NUM>) relative to said third and fourth axis (C, D), moving parallel to said fifth axis (X);
characterized in that said rear (<NUM>) comprises an end cross member (<NUM>) of said body (<NUM>);
said first electric motor (<NUM>, <NUM>) and a first braking element (<NUM>, <NUM>) being accommodated in a second compartment (<NUM>) delimited by said cross member (<NUM>) on the opposite side of said third and fourth axis (C, D), moving parallel to said fifth axis (X);
said first braking element (<NUM>, <NUM>) being operatively connected to said first output shaft (<NUM>, <NUM>) and capable of being selectively operated so as to exert a first braking torque upon said first output shaft (<NUM>, <NUM>);
said first braking element (<NUM>, <NUM>) being arranged on the opposite side of said electric motor (<NUM>, <NUM>) relative to said third and fourth axis (C, D), moving parallel to said fifth axis (X).