Motor vehicle

Abstract

To improve the stability and handling of three-wheel motor vehicles with two front wheels. [Solution] The motor vehicle comprises a front carriage frame, a pair of front wheels kinematically connected to the front carriage frame by an articulated quadrilateral, a steering bar mechanically associated with the handlebar, and wheel support elements for each wheel via first and second roll hinges and first and second steering hinges, and when the wheels are straight and parallel to the forward direction, the first and second steering hinges are offset in the longitudinal direction from the cross member of the articulated quadrilateral, and with respect to a projection plane parallel to the ground, the straight lines connecting the steering axes (S'-S', S''-S'') of the wheels and the first and second steering hinges intersect at the support points of the rear wheels on the ground.

Description

[Technical Field]

[0001] The present invention relates to an angle-adjustable front carriage of a motor vehicle and the motor vehicle. [Background technology]

[0002] As is known, there have been three-wheeled motor vehicles in the past, with a driven rear wheel and two steering and leaning wheels, i.e., with a forward rolling or leaning action.

[0003] Thus, the rear wheels are intended to provide torque and traction, while the twin front wheels are intended to provide direction for the vehicle.

[0004] By using two front wheels instead of two rear wheels, the differential torque transfer is avoided, which allows for cost and weight savings on the rear axle.

[0005] The twin wheels on the front carriage allow for lean and roll in addition to steering, and in this way, compared to a tricycle with two wheels on the rear axle, a vehicle with two wheels on the front carriage is equivalent to a true motorbike, as the vehicle can lean when cornering, just like a motorbike.

[0006] However, compared to motor vehicles with only two wheels, such vehicles with two pairs of wheels on the front carriage have greater stability guaranteed by the dual placement of the front wheels on the ground, similar to that provided by automobiles.

[0007] The front wheels are kinematically connected to one another via kinematic mechanisms, for example by interposition of articulated quadrilaterals, making them capable of rolling and / or steering synchronously and in a mirrored manner.

[0008] In particular, to drive a vehicle with two front wheels, the rotation of the handlebars must be connected to the rotation of the wheels and is therefore also interconnected in the steering movement.

[0009] In principle, the wheels can be connected by a single or two steering bars; in the latter case, two identical rods can be used, arranged symmetrically relative to the vehicle's median plane, or a first rod can be provided to connect the steering to a single wheel and a second rod can alternatively be provided to connect the two wheels to each other.

[0010] The actual steering angle formed by each individual wheel depends not only on the driver's wishes, expressed by turning the handlebars, but also on the movement of the wheel's steering or spring suspension (also called yaw). This interaction is called steering correction and can be consciously used to change the vehicle's behavior. For example, corrections are used to compensate for wheel movement determined by the suspension, which is often simplified and takes advantage of the fact that the steering gear ratio helps filter what is perceived by the driver.

[0011] Therefore, the geometric definition of the steering system is essential for good dynamic behavior of the vehicle, and the usual steering corrections are limited as much as possible, since the wheels have a very wide range of motion, especially in the case of rolling, which amplifies the unwanted motions resulting from an imperfect steering strategy.

[0012] In the prior art, the most common method of connecting the steering of the wheels of a rolling front carriage is to place the steering hinges on the wheels, have a wheel base equal to the lateral sides of a quadrilateral, and have a rolling front carriage. This allows the steering hinges to be connected to a system that traces the quadrilateral, with a single rod if the quadrilateral is not disturbed, and with a double rod if the quadrilateral is disturbed. In fact, this consists of adding an identical side to the existing one of the quadrilateral.

[0013] Generally, therefore, the connection to the wheels is via a spherical hinge or a pair of cylindrical hinges incident on each other to allow roll and steering, said cylindrical hinges being arranged in a plane parallel to the centre plane of the vehicle, and although such hinges may have any relative angle, the most convenient choice is to have them perpendicular to each other and parallel to the roll and steering axes to selectively affect said movements.

[0014] As a result, it is a known construction method (used for example in a vehicle called MP3 by the same applicant) to achieve a steering wheel that is decoupled from the roll or spring suspension movement, but which has the property of steering the wheels by the same angle, and therefore this connection method is kinematically incorrect because it forces the wheels to drag on the ground because there are two separate instantaneous centers of rotation. This effect increases tire wear and makes steering more difficult the further away from the theoretical kinematic steering condition, where the front and rear axles (with one or two wheels) have a common center of instantaneous curvature, and this effect increases with the lane and steering angle as well as the frictional forces on the ground between the tires and the ground.

[0015] Instead, in automobiles, kinematic steering is common, even in the case of the front carriage of a vehicle with parallel wheel steering, when, for example, one wants to compensate for an unbalanced weight distribution at the rear by taking advantage of increased retention at the front. In particular, kinematic mechanisms similar to kinematic steering have been known since the 19th century, known as Jantaud when placed behind the axle of the front wheels, and Ackermann when placed in front of said axle, and this involves placing a steering bar at any distance parallel to the front axle, as long as the hinges at its ends are on a line joining the centre of the rear axle (in the case of a tricycle, the centre of the single rear wheel) and each front wheel.

[0016] An example of a two-in-front, one-in-rear tricycle configuration according to Jantaud and Ackermann's kinematic steering is diagrammed in Figure 1c.

[0017] Since a car has no macroscopic roll, its diagram is usually represented in plan view, and when the vehicle is not rolling, the diagram continues to represent the case when it rolls at a very limited angle, while as the roll angle increases the diagram becomes more complex because the triangle in which the wheels rest on the ground is deformed and the wheels move vertically according to the angle imposed by the rolling quadrilateral (so that the inner wheels "rise" and the outer wheels "descend" relative to the vehicle frame), compromising the uniqueness of the instantaneous center of rotation instead of showing the absence of roll.

[0018] If the center of the spherical hinge or pair of cylindrical hinges (equivalent to a spherical hinge) is located on the wheel side presented by the kinematic steering, the length of the steering bar assumes different values ​​of the quadrilateral width (lower for a Jantaud setting aft of the steering axle / higher for an Ackermann setting forward of the steering axle), and the higher the coupling between steering and roll, the greater this difference.

[0019] For example, if one imagines rolling a vehicle fitted with a quadrilateral and fitted in a front view, the shortest bar of the quadrilateral will force the wheels to splay forward.

[0020] As a result, in the automotive industry, the Jantaud or Ackermann solutions are effective because they do not involve a coupling between steering and rolling, such that a low roll angle of the vehicle impairs the dynamic behavior of the vehicle in terms of tire wear and resistance, i.e., difficulty in steering. On the contrary, such parameters are obviously important in tilting vehicles, in which case the roll angle, and therefore the corresponding coupling between steering and roll, is larger and far from negligible. Moreover, the wear and increased steering stiffness, which in a car are well hidden from the user, would instead become unacceptable in a motorcycle. In fact, in a car, tires have a service life of about four times as long as in a motorcycle, and when it comes to steering, cars now generally utilize power steering systems, which virtually compensate for the increased effort (something that motorcycles do not offer).

[0021] It is therefore clear that the kinematic steering solutions known from the automotive industry are not applicable in the case of three-wheeled leaning motorcycles.

[0022] Among other things, it should be appreciated that a leaning three-wheel motorcycle is designed to provide the user with the handling of a two-wheel motorcycle, while at the same time providing the stability and safety of a four-wheel vehicle.

[0023] The two stated goals are diametrically opposed, since greater stability requires the presence of additional elements (such as a third wheel and its relative motion mechanism) compared to a two-wheeled motor vehicle, which necessarily pushes down on the vehicle structure.

[0024] Moreover, the presence of "only" three wheels cannot guarantee the stability and road-holding of a four-wheeled vehicle.

[0025] It is therefore essential to develop a tricycle that can reconcile these opposing objectives and at the same time ensure stability and handling, as well as reliability and low cost.

[0026] To achieve this objective, a specific geometry of the front part of the frame or front carriage and the steering mechanism of the tilting and steering front wheels must be developed to support the front wheels during their steering and tilting movements, while ensuring safety, stability, reliability, as well as agility of operation, limited effort used, and good handling for the user. Summary of the Invention

[0027] To solve the above problems, many solutions have been adopted up to now in the past on tricycles where two of the wheels are on the front carriage.

[0028] Such prior art solutions fail to optimize the stability and handling needs mentioned above. [Problem to be solved by the invention]

[0029] Therefore, a need is felt to overcome the drawbacks and limitations discussed with reference to the prior art. [Means for solving the problem]

[0030] This object is achieved by the motor vehicle described in claim 1.

[0031] Further features and advantages of the present invention will become more clearly apparent from the description given below of preferred, non-limiting embodiments thereof. [Brief explanation of the drawings]

[0032] [Figure 1a] 1 is a perspective view of a motor vehicle according to an embodiment of the present invention with some elements removed; FIG. [Figure 1b] 1 is a front view showing a front carriage of a motor vehicle according to an embodiment of the present invention. [Figure 1c] 1 is a schematic plan view of a motorcycle with three wheels, two front-steering wheels and a rear wheel, in which the steering bar is positioned ahead of the direction of travel when arranged according to Ackermann kinematic steering, and behind the direction of travel when arranged according to Jantaud kinematic steering. [Figure 2] 1 is a perspective view showing a front carriage of a motor vehicle according to an embodiment of the present invention. [Figure 3] 3 is a perspective view of the front carriage of FIG. 2 as viewed from the side of arrow III of FIG. 2. FIG. [Figure 4] FIG. 3 is a perspective view showing details of the front carriage of FIG. 2. [Figure 5] 5 is a perspective view showing details of the front carriage of FIG. 4 as seen from the side of arrow V of FIG. 4. FIG. [Figure 6] FIG. 10 is a perspective view showing a front carriage of a motor vehicle according to another embodiment of the present invention. [Figure 7] 7 is a view showing the front carriage of FIG. 6 from the side of arrow VII of FIG. 6. [Figure 8]8 is a view showing the front carriage of FIG. 6 from the side of arrow VIII of FIG. 6. [Figure 9] FIG. 10 is a perspective view showing a front carriage of a motor vehicle according to another embodiment of the present invention. [Figure 10] 10 is a view of the front carriage of FIG. 9 from the side of arrow X of FIG. 9. [Figure 11] 10 is a view of the front carriage of FIG. 9 from the side of arrow XI of FIG. 9. [Figure 12] FIG. 10 is a perspective view showing a front carriage of a motor vehicle according to another embodiment of the present invention. [Figure 13] 13 is a view showing the front carriage of FIG. 12 from the side of arrow XIII of FIG. 12. FIG. [Figure 14] 14 shows detail XIV of FIG. 13 from a different angle. [Figure 15] 14 shows detail XIV of FIG. 13 from a different angle. [Figure 16] 14 shows detail XIV of FIG. 13 from a different angle. [Figure 17] FIG. 17 is a plan view showing a motor vehicle equipped with the front carriage of FIGS. 12 to 16. DETAILED DESCRIPTION OF THE INVENTION

[0033] Elements and parts of elements that are common to the embodiments described hereinafter will be indicated using the same reference numerals.

[0034] With reference to the above figures, reference numeral 4 generally indicates a schematic overview of a motor vehicle according to the invention.

[0035] As pointed out for the purposes of the present invention, the term motor vehicle is considered in its broadest sense to encompass motorcycles having at least three wheels, i.e., two aligned wheels and at least one rear wheel, as will be better explained hereinafter. Such a definition therefore includes so-called quad bikes, which have two wheels on the front carriage and two wheels on the rear axle.

[0036] The motor vehicle 4 comprises a frame 6 extending from a front carriage 8 supporting at least two front wheels 10 , 10 ′, 10 ″ to a rear axle supporting one or more rear wheels 12 .

[0037] A distinction can also be made between a left front wheel 10' and a right front wheel 10", the definitions of left and right 10', 10" being merely formal and meant relative to the driver of the vehicle. Said wheels are located to the left and right of the centerline plane MM of the motor vehicle relative to the driver's point of view when driving it.

[0038] In the following description, as well as in the drawings, quotation marks ' and '' are used to refer to symmetrical or mirrored elements of the front carriage relative to said centerline plane, and to designate parts respectively to the left and right of the front carriage relative to the driver's point of view while driving.

[0039] For purposes of the present invention, the motor vehicle frame 6 may be of any shape and size, for example, trellis, box, cradle, single or double, etc.

[0040] The motor vehicle frame 6 may be a single piece or multiple pieces, for example, the motor vehicle frame 6 may be interconnected with a rear axle frame, which may include an oscillating rear fork (not shown) that supports one or more rear drive wheels.

[0041] The oscillating rear fork can be connected to the frame 6 by a direct hinge connection or by the interposition of a lever mechanism and / or intermediate frame.

[0042] The motor vehicle front carriage 8 comprises a front carriage frame 16 and a pair of front wheels 10 , 10 ′, 10 ″ kinematically connected to the front carriage frame 16 via an articulated quadrilateral 20 .

[0043] The articulated quadrilateral 20 comprises a pair of cross members 24 , 24 ′, 24 ″ hingedly connected to the front carriage frame 16 according to a central hinge 28 .

[0044] The central hinge 28 identifies parallel central hinge axes WW.

[0045] For example, said central hinge is fitted on a front beam 32 arranged to straddle a centerline plane MM passing through the longitudinal direction XX or direction of movement of the motor vehicle.

[0046] For example, the steering mechanism connected to the handlebars (not shown) of the motor vehicle 4 pivots on a steering column that is inserted for rotation within a steering tube in the frame 6 of the motor vehicle 4 in a known manner.

[0047] The cross member 24 extends in the main transverse direction YY between opposite transverse ends 40,44.

[0048] In particular, the cross members 24 are connected together according to the opposite lateral ends 40, 44 via struts 48, 48', 48'' that pivot relative to the lateral ends 40, 44 according to lateral hinges 52.

[0049] In one embodiment, the cross members 24 , 24 ′, 24 ″ are cantilevered relative to the front beam 32 .

[0050] The cross members 24 and the struts 48 define the articulated quadrilateral 20. In particular, the quadrilateral 20 includes two cross members 24, a top cross member 24' and a bottom cross member 24'', with the top cross member 24' facing the side of the associated handlebar and the bottom cross member 24'' facing toward the ground supporting the motor vehicle 4.

[0051] The cross members 24', 24'' are not necessarily identical to one another in terms of shape, material and size, and each cross member 24 may be made of a single piece or of two or more pieces mechanically attached, for example by welding, bolts, rivets, etc.

[0052] There are two columns, specifically a left column 48' and a right column 48''.

[0053] The definition of left and right pillars 48', 48" is merely formal and is meant relative to the driver of the vehicle. Said left and right pillars 48', 48" are located to the left and right of the centerline plane MM of the motor vehicle relative to the driver's point of view while driving it.

[0054] The lateral hinges 52 are parallel to one another and define respective lateral hinge axes ZZ.

[0055] Preferably, the central hinge 28 and the lateral hinges 52 are oriented according to a medial hinge axis WW and a lateral hinge axis ZZ that are parallel to each other.

[0056] The left and right support columns 48', 48'' support the left and right front wheels 10', 10'', respectively, so that they can rotate about their respective steering axes S'-S', S''-S''. The steering axes S'-S', S''-S'' are parallel to each other.

[0057] Each post 48 extends from an upper end 60 to a lower end 64 .

[0058] The upper end 60 faces towards the top cross member 24' and the lower end 64 faces towards the bottom cross member 24''. Each front wheel includes an axle journal 56 for the front wheel 10.

[0059] According to one embodiment, each axle journal 56 is mechanically connected to a rotation pin 68 of the front wheel 10 to rotatably support the front wheel 10 about an associated rotation axis RR.

[0060] Each rotation pin 68 of the front wheel 10 is provided between the upper end 60 and the lower end 64 of a corresponding strut 48 of the articulated quadrilateral 20 .

[0061] According to a possible embodiment, the central hinge 28 and the lateral hinges 52 are parallel to each other and perpendicular to said steering axes S'-S', S''-S''. In other words, according to one embodiment, compared to a projection plane P passing through said central hinge 28, the steering axes S'-S', S''-S'' separate the central hinge axis WW and the lateral hinge axes at an angle α of 90 degrees.

[0062] According to a possible embodiment, said angle α is between 80 degrees and 120 degrees, preferably said angle α is between 90 and 110 degrees, more preferably said angle α is equal to 100 degrees.

[0063] The steering axes S'-S', S''-S'' may be inclined with respect to the projection plane P by a steering angle β between 4 degrees and 20 degrees, more preferably between 8 degrees and 16 degrees, with respect to a vertical direction NN perpendicular to the ground.

[0064] According to another embodiment, the hinges 28 and 52 can also be inclined parallel to the ground, i.e. according to a central hinge axis WW and a lateral hinge axis ZZ perpendicular to the vertical direction NN relative to the projection plane P, in this configuration the angle β is equal to 0 degrees.

[0065] Moreover, it is clear that the hinges 28 and 52 may not be perpendicular to the steering axis S'-S', S''-S'' and, in fact, as mentioned above, the angle α defined between the steering axis S'-S', S''-S'' and the central hinge axis WW and the lateral hinge axis ZZ relative to the projection plane P passing through said central hinge 28 is comprised between 80 degrees and 120 degrees.

[0066] The parallelism of the central hinge axis WW and the lateral hinge axes ZZ to the ground means that during rolling motion the inside wheels on the curve rise almost vertically upwards, with the dual benefits of isolating the rolling motion of the wheels from the horizontal braking forces (transmitted from the ground) and reducing the clearance towards the bottom of the motor vehicle.

[0067] Naturally, by inclining the central axis WW and the lateral axis ZZ with respect to the steering axes S'-S' and S'-S', in a stationary condition, the central hinge axis WW and the lateral hinge axes ZZ are parallel to the ground, and under braking conditions, and therefore under compression of the suspension of the front wheels 10', 10", said central hinge axis WW and lateral hinge axes ZZ are tilted and moved to a state substantially parallel to the ground. For example, under stationary conditions, the central hinge axis WW and lateral hinge axes ZZ intersect an angle β with the horizontal that is different from zero (corresponding to an angle formed with the vertical and perpendicular to the horizontal), and under braking and maximum compression conditions, this angle tends to zero.

[0068] It can be seen that during braking, when the central hinge axis WW and the lateral hinge axis ZZ orient themselves substantially parallel to the ground, the horizontal, and therefore parallel to the ground, braking force has no component along the translational motion, thus preventing triggering, simply wheel jolt, and is substantially perpendicular, i.e. vertical, to the ground.

[0069] In addition, it will be appreciated that the upper and lower ends 60, 64 of the struts 48', 48'' are located above and below the rotation pin 68 of each front wheel 10', 10'', and not entirely above it as occurs in prior art solutions.

[0070] In other words, each rotation pin 68 of the front wheels 10 ′, 10 ″ is provided between the upper end 60 and the lower end 64 of the corresponding strut 48 , 48 ′, 48 ″ of the articulated quadrilateral 20 .

[0071] This implies that the stiffness of the connection between each wheel 10', 10" and the articulated quadrilateral with its suspension is significantly greater than occurs in the above-mentioned solutions of the prior art, helping to make it more likely that repetitive resonances of the front wheels 10', 10" will be taken over by braking forces or asymmetrical shocks. As a result, the invention generally helps to provide a vehicle that is light, but also safe and precise, and which conveys to the driver a feeling of safety in the front carriage, in that it does not transmit vibrations or jolts at the handlebars to the user.

[0072] Furthermore, the placement of the upper and lower cross members 24', 24'' of the articulated quadrilateral in the vertical direction of the wheels moves the common center of gravity of the front carriage, and therefore the vehicle, downwards, improving the dynamic behavior of the vehicle.

[0073] The front carriage 8 is provided with a steering bar 70 kinematically associated (coupled) with a handlebar (not shown), the steering bar 70 extending between opposite lateral ends 71, 72 where it is kinematically connected to wheel support elements 73, 74 of each wheel 10', 10" joined to the struts 48', 48" for controlling the steering rotation of said front wheels 10', 10" about respective steering axes S'-S', S"-S"'.

[0074] At the lateral ends 71, 72, the steering bar 70 is kinematically connected to each wheel support element 73, 74 via first and second roll hinges 75, 76 and via first and second steering hinges 77, 78 that are perpendicular to the first and second roll hinges 75, 76, respectively.

[0075] An orthogonal hinge is understood to mean defining hinge axes that are perpendicular to one another.

[0076] The roll hinges 75, 76 are parallel to the central hinge 28 and are spaced apart from one another at a distance equal to the distance between the lateral hinges 52 of each cross member 24', 24'' and are aligned with the latter along the struts 48', 48''.

[0077] Under the condition that the wheels are straight and parallel to the direction of movement of the vehicle or the longitudinal direction XX, the first and second steering hinges 77, 78 are offset (displaced) from the cross members 24', 24'' in the longitudinal direction XX, and the first and second steering hinges 77, 78 are offset (displaced) from the cross members 24', 24'' with respect to the projection plane Q parallel to the ground. The straight lines F and G joining the rudder hinges 77, 78 and the steering axes S'-S' and S'-S' intersect at the support point V of the rear wheels on the ground and pass through the center line plane MM of the vehicle.

[0078] The first and second roll hinges 75, 76 are perpendicular to the steering axes S'-S' and S''-S'' respectively.

[0079] Preferably, said steering hinges 77, 78 are located between each roll hinge 75, 76 and the vehicle centre line plane MM.

[0080] According to one embodiment, the roll hinges 75, 76 and the steering hinges 77, 78 are cylindrical hinges and are perpendicular to each other.

[0081] According to one embodiment, at said lateral ends 71, 72, the steering bar 70 comprises cardan joints fitted with spiders (spider spokes) 79, defining roll hinges 75, 76 and steering hinges 77, 78 which are perpendicularly incident on one another.

[0082] According to one embodiment, the steering bar 70 is located rearward from the cross members 24', 24'' relative to the direction of forward movement in the longitudinal direction XX of the vehicle.

[0083] According to another embodiment, the steering bar 70 is placed forward from the cross members 24', 24'' relative to the forward direction in the longitudinal direction XX of vehicle movement.

[0084] According to one embodiment, the roll hinges 75, 76 are aligned with each other along a vertical axis CC parallel to each of the struts 48', 48'', and each vertical axis C'-C', C''-C'' is offset (displaced) relative to the corresponding steering axis S'-S', S''-S'' by a lateral distance 80 (offset) relative to a projection plane perpendicular to the vehicle centerline plane MM.

[0085] Preferably, the steering hinges 77, 78 are arranged at a predetermined distance from each other, and the straight lines F, G connecting the first and second steering hinges 77, 78 and the steering axes S'-S', S''-S'' intersect with a projection plane Q parallel to the ground at the support point V of the rear wheel on the ground and pass through the center line plane MM of the vehicle.

[0086] According to a possible embodiment, said roll hinges 75, 76 and said steering hinges 77, 78 cross each other.

[0087] In particular, roll hinges 75, 76 and steering hinges 77, 78 co-penetrate within spherical hinge 81, allowing both roll and steering functions to be performed.

[0088] According to one embodiment, the steering bar 70 is a single piece that pivots relative to the forward carriage frame 16 at a central point 82 of the forward carriage frame 16 that defines a central steering axis TT. According to a possible embodiment, said central steering axis TT is parallel to the steering axes S'-S', S''-S''.

[0089] According to another embodiment, the steering bar 70 comprises two rods 83, 84, each hinged to one of said wheel support elements 73, 74 and to the same central point 82 of the front carriage frame 16, defining a central steering axis TT. According to a possible embodiment, said central steering axis TT is parallel to said steering axes S'-S', S''-S''.

[0090] For example, a cross joint 85 is provided at the central point 82 to define a central roll hinge 86 and a central steering hinge 87 that are perpendicularly incident on each other.

[0091] According to one embodiment (Figures 14 to 17), for each front wheel 10', 10" the wheel support element 73, 74 comprises an inclined support structure 88 for the axle journal 56 of each front wheel 10', 10" which is mechanically connected to the rotation pin 68 of each front wheel 10', 10" and supports the front wheel 10', 10" rotatably about its rotation axis R'-R', R"-R"

[0092] Preferably, the tilting support structure 88 is hingedly connected to the articulated quadrilateral 20 via steering pins 90 arranged according to the upper and lower ends 60, 64 of each of the struts 48', 48", the steering hinges defining respective steering axes S'-S', S''-S'' of the wheels 10', 10'', which are parallel to each other.

[0093] Preferably, the steering axes S'-S', S''-S'' coincide with the axes of symmetry of said struts 48', 48'', respectively.

[0094] Each wheel 10', 10'' has a centreline plane of a rotation axis R'-R', R''-R'', said centreline plane of the rotation axis R'-R', R''-R'' passing through the steering axis S'-S', S''-S'' of each front wheel 10', 10'', respectively.

[0095] Preferably, said tilting support structure 88 is entirely contained within a volume 92 bounded by the edges 93 of each wheel 10', 10''.

[0096] Preferably, the volume 92 faces the centerline plane MM of the forward carriage 8, which passes through the central hinge 28. In other words, the axle journal 56 faces inward toward the centerline plane MM of the motor vehicle, and relative parts associated with the axle journal 56 are not directly visible to an outside observer.

[0097] According to a preferred embodiment, the tilting support structure 88 comprises a guide wheel 94 connected to the axle journal 56 of the front wheels 10', 10" and a support bracket 95 hinged to the articulated quadrilateral 20 via the steering pin 90.

[0098] The guide wheels 94 are connected to the rotation pins 68 and rotatably support the rotation pins 68 of the corresponding wheels 10', 10'' in accordance with the dedicated wheel mounting portions 96a.

[0099] The guide wheel 94 extends between opposite upper and lower axial ends 96, 98, and preferably at said opposite axial ends 96, 98 the guide wheel 94 is mechanically connected to connecting elements to the frame.

[0100] Such a linear guide wheel 94 defines the pivot axis TR-TR of each wheel 10', 10'.

[0101] For example, the guide wheel 94 is further hingedly connected to the support bracket 92 at opposite upper and lower axial ends 96, 98 of the guide wheel 94 by at least three tilt hinges 100, which define respective tilt axes BB and provide a rotational-translational connection between the guide wheel 94 and the support bracket 95.

[0102] Preferably, the lateral ends 40, 44 of the upper and lower cross members 24', 24'' of the articulated quadrilateral 20 are at least partially housed within lateral seats 102 made inside the struts 48', 48''.

[0103] Preferably, each guide wheel 94 is provided with braking means 104 for the corresponding wheel 10', 10''. Generally, disc brake calipers are installed.

[0104] The guide wheel 94 is further hingedly connected to the support bracket 95 according to its opposite upper and lower axial ends 96, 98 via at least three tilt hinges 100, 105, 106, 110, which define respective tilt axes BB and provide a rotational-translational connection between the guide wheel 94 and the support bracket 95.

[0105] Preferably, the guide wheels 94, support brackets 95 and tilt hinges 100, 105, 106, 110 define a peripherally closed tilt support structure 88.

[0106] According to one embodiment, the rotation pin 68 of each wheel 10', 10" is arranged inside the circumferentially closed tilting support structure 88, and / or the lateral hinge 52 and each strut 48', 48" are arranged inside the circumferentially closed tilting support structure 88.

[0107] For example, the tilt support structure 88 includes a connecting rod 111 that is doubly hingedly connected to the support bracket 95 and the guide wheel 94 at first and second tilt hinges 105, 106.

[0108] For example, the tilt support structure 88 includes a pin 108 that is hingedly connected to the support bracket 95 and the guide wheel 94 at a third tilt hinge 110 .

[0109] The pin 108 can also translate along a slot 112 made on the guide wheel 94 .

[0110] According to one embodiment, the tilt hinges 100, 105, 106, 110 are hingedly connected to the support bracket 95 and the guide wheel 94 at a tilt axis BB that is perpendicular to the rotation axis R'-R', R''-R'' of each wheel 10', 10'' and perpendicular to the steering axis S'-S', S''-S'' defined by the steering pin 90.

[0111] As mentioned above, the motor vehicle 4 according to the invention comprises at least one rear drive wheel 14 , and according to a possible embodiment the vehicle has two rear drive wheels 14 on the rear axle 12 .

[0112] For example, in such an embodiment where the motor vehicle is a four-wheel vehicle, the rear drive wheels 14 on the rear axle 12 are connected to each other and to the front wheels 10 via the articulated quadrilateral 20 as described above in the rear axle frame 13 .

[0113] As is apparent from the description, the present invention is able to overcome the drawbacks noted in the prior art.

[0114] Preferably, the present invention improves the dynamic behavior of the vehicle compared to the prior art.

[0115] In fact, when steering is straight, the steering correction becomes zero with vehicle roll and is in any case small for small steering angles, and considering that when driving a rolling vehicle, the user rarely steers more than a few degrees, the invention represents a substantial improvement over known arrangements, since curves are imposed and covered thanks to the leaning movement of the vehicle itself.

[0116] As a result, the steering or handlebars can be easily operated and turned by the user, since the steering correction is very limited and the reaction transmitted to said steering by the wheels is practically negligible, so the steering is not heavy and not cumbersome for the user to operate.

[0117] Additionally, no or negligible steering correction limits tire wear.

[0118] Moreover, the absence or negligible steering corrections convey a steering precision not found to date in a leaning three-wheel vehicle. In fact, the driver always has a significantly more accurate steering feel, i.e., a significantly smoother directional sense of the vehicle, and no abnormal steering reactions, even when cornering.

[0119] Finally, thanks to the presence of two paired front wheels, the motor vehicle according to the invention can ensure not only a high level of stability superior to that of a motorcycle with two wheels, but also the excellent handling and ease of leaning that are typical of motorcycles with only two wheels.

[0120] Those skilled in the art can make various modifications and variations to the above solution to meet their fortuitous and specific requirements, while remaining within the scope of protection of the present invention as defined by the appended claims.

Claims

1. - a front carriage frame (16); - a pair of front wheels (10', 10'') kinematically connected to said front carriage frame (16) via an articulated quadrilateral (20); - said articulated quadrilateral (20) comprises a pair of cross members (24', 24'') hinged to said front carriage frame (16) according to a central hinge (28); - the cross-members (24', 24") are connected together at their opposite lateral ends (40, 44) via struts (48, 48', 48") that pivot at the lateral ends (40, 44) at lateral hinges (52), each strut (48', 48") extending from an upper end (60) to a lower end (64), the upper end (60) facing the cross-member (24') above and the lower end (64) facing the cross-member (24") below; said cross members (24', 24") and said struts (48', 48") define said articulated quadrilateral (20); the front carriage (8) comprises a steering bar (70) mechanically associated with the handlebars, said steering bar (70) extending between its lateral ends (71, 72) and mechanically connected thereto to the wheel support elements (73, 74) of each wheel (10', 10") joined to said struts (48', 48"), for controlling the rotation of said front wheels (10', 10") about their respective steering axes (S'-S', S"-S"); the central hinge (28) and the lateral hinges (52) are oriented so as to coincide with central hinge axes (WW) and lateral hinge axes (ZZ) which are parallel to each other; A motor vehicle (4), at the lateral ends (71, 72), the steering bar (70) is mechanically connected to each wheel support element (73, 74) via first and second roll hinges (75, 76) and via first and second steering hinges (77, 78), the steering axes (S'-S', S''-S'') being defined with the central hinge axis (W-W) and the lateral hinge axes (Z-Z) by an angle (α) between 80° and 120°, or between 90° and 110°, or 90° or 100°, Under the condition that the wheels are parallel to the forward direction, the first and second steering hinges (77, 78) are disposed offset from the cross members (24', 24") in the longitudinal direction (X-X), which is the front-rear direction of the motor vehicle (4), and lines (F, G) joining the first and second steering hinges (77, 78) and the steering axes (S'-S', S"-S") intersect with a projection plane (Q) parallel to the ground at a support point (V) of the rear wheels on the ground and pass through a vertical plane (M-M) passing through the center of the motor vehicle. A motor vehicle (4).

2. The motor vehicle (4) according to claim 1, wherein the first and second roll hinges (75, 76) are perpendicular to the steering axes (S'-S', S''-S''), respectively.

3. The motor vehicle (4) according to claim 1 or 2, wherein the first and second steering hinges (77, 78) are disposed between the first and second roll hinges (75, 76) and a vertical plane (M-M) passing through a center of the motor vehicle.

4. 4. The motor vehicle (4) according to any one of claims 1 to 3, wherein the first and second roll hinges (75, 76) and the first and second steering hinges (77, 78) are cylindrical hinges that are perpendicular to each other.

5. 5. A motor vehicle (4) according to any one of claims 1 to 4, wherein at the lateral ends (71, 72) the steering bar (70) has cardan joints adapted to a spider (79) defining the first and second roll hinges (75, 76) and the first and second steering hinges (77, 78) which are perpendicularly incident on each other.

6. 6. The motor vehicle (4) according to any one of claims 1 to 5, wherein the steering bar (70) is installed rearward from the cross members (24', 24'') relative to a forward direction in the longitudinal direction (X-X) of movement of the vehicle.

7. 6. The motor vehicle (4) according to any one of claims 1 to 5, wherein the steering bar (70) is installed in front of the cross members (24', 24'') relative to a forward direction in the longitudinal direction (X-X) of movement.

8. the first and second roll hinges (75, 76) are arranged on vertical axes (C'-C', C''-C'') parallel to each of the struts (48', 48'') and are parallel to each other, and each vertical axis (C'-C', C''-C'') is offset by a lateral distance (80) from the corresponding steering axis (S'-S', S''-S'') with respect to a projection plane perpendicular to a vertical plane (M-M) passing through the center of the motor vehicle; A motor vehicle (4) according to any one of claims 1 to 7, wherein the first and second steering hinges (77, 78) are arranged at a predetermined distance from each other, and lines (F, G) joining the first and second steering hinges (77, 78) and the steering axis (S'-S', S''-S'') intersect with a projection plane (Q) parallel to the ground at a support point (V) of the rear wheel on the ground and pass through a vertical plane (M-M) passing through the center of the motor vehicle.

9. 9. The motor vehicle (4) of claim 8, wherein the first and second roll hinges (75, 76) and the first and second steering hinges (77, 78) intersect with each other.

10. 10. The motor vehicle (4) of claim 1, wherein the steering bar (70) is an integral part that pivots relative to the forward carriage frame (16) at a central point (82) of the forward carriage frame (16) that defines a central steering axis (T-T).

11. 10. The motor vehicle (4) according to any one of claims 1 to 9, wherein the steering bar (70) comprises two rods (83, 84), each hingedly connected to one of the wheel support elements (73, 74) and to the same central point (82) of the front carriage frame (16), thereby defining a central steering axis (T-T).

12. 12. A motor vehicle (4) according to claim 10 or 11, characterized in that the central point (82) is provided with a cross joint (85) defining a central roll hinge (86) and a central steering hinge (87) which are perpendicularly incident on each other.

13. For each front wheel (10', 10"), the wheel support element (73, 74) comprises an inclined support structure (88) for the axle journal (56) of each front wheel (10', 10"), which is mechanically connected to the rotation pin (68) of the front wheel (10', 10"), and rotatably supports the front wheel (10', 10") about its rotation axis; A motor vehicle (4) according to any one of claims 1 to 12, wherein the tilting support structure (88) is hingedly connected to the articulated quadrilateral (20) via steering pins (90) arranged at the upper end (60) and the lower end (64) of each strut (48', 48"), the steering pins (90) defining respective steering axes (S'-S', S"-S") of the wheels (10', 10") parallel to one another.

14. The motor vehicle (4) according to claim 13, wherein the steering axis (S'-S', S''-S'') is defined by the struts (48', 48'').

15. A motor vehicle (4) according to claim 13 or 14, wherein each wheel (10', 10") has a plane (R'-R', R''-R'') perpendicular to the axis of rotation and passing through the center of the wheel, and each plane (R'-R', R''-R'') passes through the steering axis (S'-S', S''-S'') of each front wheel (10', 10'').

16. The tilted support structure (88) a connecting member connected to said rotation pin (68) of the front wheels (10', 10'') at a dedicated wheel attachment; - a support bracket (95) hinged to the articulated quadrilateral (20) via said steering pin (90), The motor vehicle (4) according to claims 13 to 15, wherein the connecting member is further hingedly connected to the support bracket (95) according to upper and lower axial ends (96, 98) via at least three hinges (100, 105, 106, 110), defining respective axes (B-B) and forming a rotational-translational connection between the connecting member and the support bracket (95).

17. 17. The motor vehicle (4) of claim 16, wherein the connecting member, the support bracket (95), and the at least three hinges (100, 105, 106, 110) define an interconnected tilting support structure (88).

18. 18. The motor vehicle (4) of claim 17, wherein the rotation pin (68) of each wheel (10', 10") is located inside the circumferentially surrounding tilting support structure (88), and / or the lateral hinge (52) and each of the struts (48', 48") are located inside the circumferentially surrounding tilting support structure (88).

19. 19. The motor vehicle (4) of claim 16, 17 or 18, wherein the tilting support structure (88) comprises a connecting rod (111) doubly hingedly connected to the support bracket (95) and the connecting member at first and second hinges (105, 106).

20. 20. The motor vehicle (4) of claim 16, 17, 18 or 19, wherein the tilting support structure (88) comprises a plate (108) hingedly connected to the support bracket (95) and the connecting member at a third hinge (110).

21. The motor vehicle (4) according to any one of claims 16 to 20, wherein the hinges (100, 105, 106, 110) are hingedly connected to the support bracket (95) and the connecting member at an inclined axis (B-B) that is perpendicular to the rotation axis of each wheel (10', 10"), perpendicular to a plane (R'-R', R''-R'') passing through the center of the wheel, and perpendicular to a steering axis (S'-S', S''-S'') defined by the steering pin (90).

22. 22. The motor vehicle (4) of any one of claims 1 to 21, wherein the lateral ends (40, 44) of the upper and lower cross-members (24', 24'') are at least partially housed within lateral seats (102) made inside the struts (48', 48'').

23. A motor vehicle (4) according to any one of claims 1 to 22, wherein the steering axis (S'-S', S''-S'') is inclined by a steering angle (β) of 4 to 20 degrees with respect to a projection plane (P) passing through the central hinge (28) compared to a vertical direction (N-N) perpendicular to the ground.

24. A motor vehicle (4) according to any one of claims 1 to 22, wherein the steering axis (S'-S', S''-S'') is inclined by a steering angle (β) of 8 to 16 degrees with respect to a projection plane (P) passing through the central hinge (28) compared to a vertical direction (N-N) perpendicular to the ground.

25. 25. The motor vehicle (4) of any one of claims 1 to 24, wherein the central and lateral hinges (28, 52) define the central hinge axis (WW) and the lateral hinge axis (Z-Z) parallel to the ground, i.e., perpendicular to a vertical direction (N-N) perpendicular to the ground.

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