Technical field

This invention relates to the field of electric vehicles. In particular, the invention relates to an electric quadricycle.

Background art

The term‘quadricycle’ refers to a vehicle classified in category L6e (light quadricycle) or L7e (heavy quadricycle), and relative sub-categories, according to the EU regulations in force at the time of filing this patent application.

More specifically, category L6e includes four-wheeled vehicles with a maximum speed < 45 km/h, a weight < 425 kg, a power < 6 kW and a maximum of two seats, including the driver’s seat.

Category L7e includes quadricycles similar to those classified as L6e but which have a maximum speed <90 km/h, a weight of < 450 kg, a power <15 kW and a maximum of two seats, including the driver’s seat.

This type of vehicle is relatively new and, thanks to the reduced dimensions and the considerable efficiency, is considered to be an alternative both to the so-called ‘city car’ and mopeds, which are particularly valid in urban contexts.

The light quadricycles are not currently covered In Italy and in the majority of countries by the strict safety tests to which normal passenger vehicles are subjected.

Design criteria such as the reduction of weight, overall dimensions and prices (compared to the other types of vehicles due to the lightweight materials used and low production volumes) currently tend to prevail over passenger safety.

The crash tests, which have been recently introduced by the EU control bodies for checking the safety of light and heavy quadricycles (in particular for category L7e), confirm the mediocre quality levels of this type of vehicle in this sector. In particular, the experimental evidence demonstrates various failings of the frames of the light quadricycles on the market with regard to the behaviour following impact.

Disadvantageously, the known light quadricycles are not equipped with front“crash boxes”, that is to say, a front structure designed to absorb the impact energy by plastic deformation, or they are equipped with inadequate“crash boxes”, which concentrate too many impact forces in limited portions of the frame or which, when they deform, constitute themselves a risk to the safety of the occupants.

A further critical issue with light quadricycles consists in the position of the front wheels which are necessarily located, due to the reduced size, close to the front end of the vehicle and the legs of the occupants.

For this reason, during a front impact of the vehicle the front wheels undergo a considerable impact force and tend to withdraw, creating forces on the frame through the suspension arms. This behaviour results in the discharging of considerable impact forces directly on the frame through the wheels, which bypass the crash box and can result in injuries to the occupants due to the strong deceleration. In addition, the forces between the suspension arms and the frame can determine a collapse of the fixing portions of the latter, causing the wheels to withdraw, which, by rotating about the above-mentioned fixing portions, results in the risk of entering the portion of the cabin occupied by the legs of the passengers and causing serious injuries.

Disclosure of the invention

In this context, the technical purpose which forms the basis of the invention is to provide an electric quadricycle which overcomes at least some of the above-mentioned drawbacks of the prior art.

In particular, the aim of the invention is to provide an electric quadricycle which is able to improve safety of prior art quadricycles with respect to front impacts, protecting the weight contained.

The technical purpose indicated and the aims specified are substantially achieved by an electric quadricycle comprising the technical features described in one or more of the appended claims.

Further features and advantages of the invention are more apparent in the non-limiting description which follows of a preferred embodiment of an electric quadricycle illustrated in the accompanying drawings.

Brief description of the drawings

The description is set out below with reference to the accompanying drawings which are provided solely for purposes of illustration without restricting the scope of the invention and in which:

- Figure 1 is a perspective view of an electric quadricycle according to the invention, with some hidden components for sake of simplicity;

- Figure 1 A is a perspective view of a detail of the quadricycle of Figure 1 ;

- Figure 2 is a side view of the quadricycle of Figure 1 , with some parts removed for sake of simplicity;

- Figure 3 is a top cross section view of the quadricycle of Figure 1 , with some parts removed for sake of simplicity;

- Figure 4A is a side view of a detail of the quadricycle of Figure 1 ;

- Figure 4B is a top view of the detail of Figure 4A;

- Figure 5A is a top cross section view of a detail of the quadricycle of Figure 1 ;

- Figure 5B is a view from below of the detail of Figure 5A.

Detailed description of preferred embodiments of the invention

With reference to the accompanying drawings, an electric quadricycle is indicated generically with the numeral 1.

The quadricycle 1 , comprises a main frame 10 made of aluminium alloy, preferably of the type 6063-T6. The main frame 10 consists of preferably tubular structures which extend around the space provided for the occupants and luggage and are configured for supporting a plurality of laminated walls and a plurality of windows to form the outer bodywork of the quadricycle 1. The main frame 10 configured in this way forms a resistant protective structure around the occupants of the quadricycle 1. The quadricycle 1 also comprises a deformable structure 20 made of aluminium alloy, preferably of the type 6063-T6, positioned in a front portion of the quadricycle 1 , in front of the main frame 10. The deformable structure 20 is plastically deformable so as to absorb at least partly the kinetic energy of the quadricycle 1 during a front impact, reducing the quantity of energy that is discharged onto the main frame 10 and contributing to prevent injuries to the occupants of the quadricycle 1.

The deformable structure 20 comprises a plurality of beams 22, oriented in a direction substantially parallel to a longitudinal axis‘L’ of the quadricycle 1 , wherein the longitudinal axis‘L’ is defined along the direction of travel of the quadricycle 1 in a straight line.

The beams 22 comprise a plurality of holes 24 distributed along their length in such a way as to have increasing cross section away from the main frame 10 and create increasingly significant zones of weakness. Advantageously, the holes 24 are configured for determining a gradual and programmed compression yield of the deformable structure 20.

In a preferred embodiment, the quadricycle 1 comprises one or more foam bodies 24 mounted on the front of the deformable structure 20 for forming respective bumpers. Figure 1 A illustrates a solution wherein two foam bodies 24 are mounted on the deformable structure 20.

Advantageously, the quadricycle 1 comprises a rigid connecting structure 30 made of steel, preferably of the type S355JR, interposed between the main frame 10 and the deformable structure 20.

The connecting structure 30 is configured for transferring longitudinal loads between the deformable structure 20 and the main frame 10, for distributing them on the latter in such a way as to favour maintaining its structural integrity during a front impact.

The connecting structure 30 has a plurality of lower front coupling portions 32 and a plurality of upper front coupling portions 34, respectively connected to respective coupling portions of the deformable structure 20 in such a way as to support the latter and allow transmission of impact loads from the deformable structure 20 to the connecting structure 30 during the collapse of the former following a front impact.

In the embodiment illustrated, the connecting structure 30 comprises two lower front coupling portions 32 and two upper front coupling portions 34. The connecting structure 30 also has a plurality of inner rear coupling portions 36 and a plurality of outer rear coupling portions 38, wherein the terms ‘inner’ or ‘outer’ refers to the location with reference to the longitudinal axis ‘L’. The outer rear coupling portions 38 are in effect positioned at the sides of the inner rear coupling portions 36.

The inner and outer rear coupling portions 36 and 38 are connected to respective lower coupling portions of the main frame 10 and are configured to transmit to them the impact loads coming from the deformable structure 20, distributing them in such a way as to mitigate structural damage.

In the embodiment illustrated, the connecting structure 30 comprises two inner rear coupling portions 36 and two outer rear coupling portions 38.

The connecting structure 30 also has a plurality of raised coupling portions 40, connected to respective upper coupling portions of the main frame 10 for transmitting the loads and guaranteeing, together with the inner and outer rear coupling portions 36 and 38, the rigidity of the connection between the main frame 10 and the connecting structure 30 and its compression stability during any impact.

The main frame 10 has a transversal width greater than the deformable structure 20, since the latter is limited in width by the presence of the front wheels 50 and the front suspension of the quadricycle 1.

Preferably, the connecting structure 30 has a plurality of structural profiles diverging relative to the longitudinal axis‘L’ of the quadricycle 1 between the deformable structure 20 and the main frame 10.

Preferably, two rectilinear longitudinal profiles 42 are interposed between the lower front coupling portions 32 and the inner rear coupling portions 36, oriented parallel to the longitudinal axis‘L’ in such a way that each of them connects directly a lower front coupling portion 32 to an inner rear coupling portion 36 for transmitting the longitudinal loads between them. The term‘profile’ as used in this description means a beam or elongate structural element such as, for example, a bar or a plate.

Moreover, the connecting structure 30 has two flat oblique profiles 44, that is to say, positioned in such a way that their main direction of extension lies in a horizontal plane of the quadricycle 1 , that is to say, a plane substantially parallel to the supporting surface of the wheels.

Each profile oblique 44 has an end connected to a middle portion of a respective longitudinal profile 42 and an opposite end connected to one of the outer rear coupling portions 38, in such a way to distribute part of the loads which develop in the longitudinal profiles 42 to the outer rear coupling portions 38 and prevent excessive force concentrations in the main frame 10 at the inner rear coupling portions 36.

Preferably, the angle between the longitudinal profiles 42 and the oblique profiles 44 is between 40° and 50°, even more preferably between 44° and 46°.

In a preferred embodiment, the connecting structure 30 also comprises two inclined profiles 46, interposed between the upper front coupling portions 34 and the outer rear coupling portions 38, in such a way that each inclined profile 46 connects an upper front coupling portion 34 to an outer rear coupling portion 38. Advantageously, the inclined profiles 46 allow the transfer of the loads between the upper front 34 and outer rear 38 coupling portions, favouring the uniformity of loads in the zones of contact with the main frame 10 during a front impact and increasing the rigidity of the connecting structure 30.

Preferably, the inclined profiles 46 have an angle relative to the longitudinal axis ‘L’ of between 20° and 30°, even more preferably between 26° and 27°. Moreover, they have an angle relative to the horizontal plane of the quadricycle 1 of between 20° and 30°, preferably between 23° and 24°. The quadricycle 1 comprises a front suspension system 60, which in turn comprises a plurality of arms 62 associated with respective elastic elements 70 to support together with them the front wheels 50, according to an arrangement known as MacPherson.

Preferably, each arm 62 has a Ύ” shape, and forms a main branch 64 from which diverge a first secondary branch 66 and a second secondary branch 67.

In a preferred embodiment, the first secondary branch 66 is substantially rectilinear and aligned with the main branch 64, which is also rectilinear. The second secondary branch 67, on the other hand, is preferably curved along the relative direction of extension and, at the fork of the Ύ”, is bent with respect to the main branch 64 by an angle close to 90°.

The curve of the second secondary branch 67 is preferably between 70° and 80°, even more preferably between 74° and 76°. In the embodiment illustrated, the above-mentioned curve also has a radius of curvature of between 35 mm and 60 mm, preferably between 47 mm and 48 mm.

Each arm 62 is hinged to a lower portion 5 of the quadricycle 1 , in particular of the connecting structure 30, at the first and second secondary branches 66 to 67, by means of lower hinges 68 connected to respective ends of the first and second secondary branch 66 and 67.

The lower hinges 68 are rotatable about a common hinge axis, substantially parallel to the horizontal plane of the quadricycle 1 and preferably parallel to a longitudinal axis‘L’ of the quadricycle 1.

The main branch 64 of each arm 62 has an outer end 65 connected to the hub 52 of a front wheel 50 in such a way as to allow a rotation of it and allowing the quadricycle 1 to be steered.

Advantageously, the arms 62 have a compliant portion 63 in the vicinity of the outer end 65, in particular at the main branch 64, designed to yield following a front impact of the quadricycle front 1 such as to collapse the deformable structure 20. Advantageously, the compliant portion 63 and the deformable structure 20 are configured to act in synergy during an impact of the quadricycle 1 and collapse together in such a way as to avoid concentrations of force in the connecting structure 30 and in the main frame 10.

Preferably, the lower hinges 68, the lower portion 5 and the first and second secondary branches 66 to 67 are configured to rigidly withstand a front impact of the quadricycle 1 such as to collapse the deformable structure 20 and the compliant portion 63, in such a way to protect the occupants from any injuries. The expression‘rigidly withstand’ means that these components are configured not to undergo plastic deformation if subjected to forces in the order of magnitude of the minimum force sufficient to collapse the above-mentioned yieldable parts.

Preferably, each elastic element 70 comprises a spring and a shock absorber and has a first end connected to a hub 52 and a second end connected to a middle portion of the quadricycle 1 , in particular a portion of the main frame 10 close to a upper coupling portion connected to one of the raised coupling portions 40 of the connecting structure 30.

Preferably, the elastic elements 70 are configured to withstand a front impact of the quadricycle 1 such as to collapse the deformable structure 20 and the compliant portion 63 of the arms 62 in such a way as to constrain the respective front wheels 50 to the quadricycle 1 during impact, allowing the rotation about an axis of extension of the elastic elements 70.

The quadricycle 1 comprises two steering arms 75 hinged to the hubs 52 at respective head joints. Preferably, the steering arms 75 and the above- mentioned head joints are configured to withstand at least initially a front impact such as to collapse the deformable structure 20, so as to constrain the front wheels 50 following collapse of the arms 62.

The invention achieves the set aim by obviating the drawbacks of the prior art. The interposing of a rigid connecting structure between a deformable structure made of aluminium alloy and the main frame of the quadricycle, together with the configuration of the coupling portions between the various parts described above, allow an appropriate transmission of loads between the deformable structure and the main frame during a front impact. This favours the structural integrity of the main frame and helps to prevent lesions to the occupants due to yield of the frame.

The solution described also makes it possible for the deformable structure to act effectively during impact, reducing acceleration which are potentially harmful to the occupants which are subjected to them.

The compliant portion of the arms described allows their collapse during impact in such a way that these cannot transmit the impact forces from the wheel to the connecting structure and bypass the deformable structure. The yielding of the arms also makes it possible to avoid deformation of the hinges and eliminate the risk that, by pivoting on them, the front wheels can withdraw, thereby deforming and entering the passenger compartment.