Tilting suspension system especially for a three- or multi-wheel vehicle

Abstract

The present invention concerns a steerable and tilting suspension system (1) with mechanical support, for a vehicle (2) comprising a frame (10) and three or more wheels of which at least a first wheel (11) and a second wheel (12) are respectively arranged on opposite sides of said vehicle (2), said suspension system (1) comprising a pair of hydraulic suspensions (40) having a first end (40a) adapted to be hinged to said frame (10) and a second end (40b), opposite to said first end (40a), hinged to a respective support arm (70), each support arm (70) being configured to be hinged, at a first end (70a), to said frame (10) and at a second end (70b), opposite to said first end (70a), to a support element (60) of, respectively, said first wheel (11) and said second wheel (12). According to the invention, the suspension system (1) comprises at least one pair of elastic springs (30) each configured to support a respective support arm (70) generating an elastic force in opposition to the force of gravity.

Description

[0001] TILTING SUSPENSION SYSTEM ESPECIALLY FOR A THREE- OR MULTI-

[0002] WHEEL VEHICLE

[0003] FIELD OF THE INVENTION

[0004] The present invention concerns a steerable and tilting suspension system with mechanical support, particularly for a three- or multi-wheel vehicle, and in particular a hydraulic suspension system combined with a mechanical system. In detail, the present invention refers to motorcycles having at least three wheels, two of which side by side, and which are able to tilt laterally thanks to the presence of a connection system between the two side-by-side wheels.

[0005] STATE OF THE ART

[0006] The vehicles referred to are vehicles with three or more wheels, such as motorcycles, tricycles, quadricycles and scooters.

[0007] Three-wheeled vehicles are currently known, where the two wheels on the front part of the vehicle are steerable and swinging, while the rear wheel is a drive wheel, with technical characteristics similar to the technical characteristics of the rear wheels of traditional twowheeled motorcycles or scooters. Four-wheeled vehicles are also known, in which the front part is similar to that of the three-wheeled vehicles mentioned above, while the rear part has a pair of swinging wheels.

[0008] As is known, vehicles with three or more wheels comprise suspension systems that can be of the mechanical or hydraulic type, wherein the latter, although more complex, are generally more efficient.

[0009] Among the hydraulic suspension systems for vehicles with three or more wheels, and in particular for the pairs of wheels aligned on the same axis and swinging thanks to a pendulum system, for example the one described in patent document WO 01 / 36253 Al can be mentioned. In this solution, a hydraulic connection is provided between the two shock absorbers associated with the pair of wheels aligned on the same axis, capable of counterbalancing the reciprocal movements of the wheels of the pair of wheels.

[0010] However, this solution is not without drawbacks, including the fact that, in the event that the vehicle is lifted off the ground, for example following a jump on a bump, or even in the event of lifting the vehicle for maintenance purposes, the suspension system is lifted together with the vehicle frame, but the wheels, and the other swinging components, with the various arms and articulation levers, are lowered, causing a depression in the hydraulic chamber, the oil, the shock-absorbing cylinder. Such a depression is however particularly harmful in hydraulic systems of the type adopted herein, as it may cause air inclusions in the oil, making the hydraulic suspension itself inefficient and / or unusable.

[0011] In addition, when the vehicle comes back into contact with the ground, after the hydraulic chamber of the shock absorber has gone into depression, an increase in pressure occurs in the same that could damage the suspension system itself. This is particularly true in the case of a jump due to a bump, following which the subsequent impact with the ground causes an unwanted and often harmful pressure peak.

[0012] Patent document EP 2046589 Bl aims to solve this technical problem by using pressurized gas (air, nitrogen or the like) to fill the lower chambers of the shock-absorbing cylinders. In this way, the pressure present in these chambers prevents the lowering of the wheels, and other swinging components, with the various arms and articulation levers and consequently it prevents the generation of unwanted depressions inside the upper hydraulic chambers.

[0013] However, also this solution is not free from drawbacks. In particular, it has been found that the effect of the pressure present in the lower chambers of the hydraulic system is such that it causes an increase in frictions due to the presence of the seals of the rods that must make the system itself hermetic.

[0014] The frictions introduced by this gas solution negatively affects the smoothness of the suspension, making the driving of the vehicle less efficient; above all, the friction of first detachment, called "stick slip" in the literature, produces significant problems and inconveniences even while driving the vehicle.

[0015] In addition, the sealing of the lower chambers, under pressure, guaranteed by the dynamic seals, deteriorates physiologically over time, due to air leakages from the rods of the suspension. As a result, a loss of pressure occurs over time which in the long run leads to functional problems with the suspension itself. It is therefore necessary to plan control and restoration interventions of the vehicle, during maintenance, with consequent costs for the user.

[0016] SUMMARY OF THE INVENTION

[0017] In light of the above, the task of the present invention is to realise a steerable and tilting suspension system with mechanical support, particularly for a three- or multi -wheel vehicle that overcomes the limits of the prior art allowing to make the driving of the vehicle safer and more comfortable.

[0018] Within the scope of this task, the object of the present invention is to realise a suspension system that is robust and durable over time, and in which the operating frictions are reduced to a minimum and do not have a negative impact on either the driving of the vehicle or its durability.

[0019] Another object of the present invention is to realise a suspension system that allows to reduce the specific maintenance intervals, consequently also reducing the maintenance costs for the user.

[0020] A further object of the invention consists in realising a suspension system that is able to give the broadest guarantees of reliability and safety in use.

[0021] Yet another object of the invention consists in realising a suspension system that is easy to realise and economically competitive if compared to the prior art.

[0022] The task set out above, as well as the aforementioned purposes and others that will become clearer later, are achieved by a suspension system according to claim 1.

[0023] Other features are provided in the dependent claims.

[0024] LIST OF FIGURES

[0025] Further characteristics and advantages of the present invention will become more apparent from the exemplary but non-limiting description of a preferred embodiment of the present invention illustrated with the aid of the attached drawings in which:

[0026] - figure 1 and figure la represent a perspective view of a three-wheeled vehicle equipped with the suspension system according to the invention;

[0027] - figure 2 represents a perspective view of the vehicle of figure 1 in a tilted position with respect to the vertical direction;

[0028] - figure 3 and figure 3a represent a front view of the vehicle of figure 1 without the wheels;

[0029] - figure 4 represents a perspective view of the suspension system, according to the invention;

[0030] - figure 4a represents a front view of the suspension system, according to the invention, with details in section;

[0031] - figures 5 and 5a represent a front view of the vehicle of figure 1, in a tilted position and without the wheels;

[0032] - figure 6 represents a perspective view of some components of the suspension system, according to the invention;

[0033] - figures 7 and 7a represent a sequence of assembly of some components of the suspension system, according to the invention;

[0034] - figures 8, 8a and 8b represent a tensioning sequence of a spring forming part of the suspension system, according to the invention, using a special tool;

[0035] - figure 9 represents a perspective view of the special tool of figures 8, 8a and 8b; - figures 10 and 10a show two different preload positions of the spring forming part of the suspension system, according to the invention;

[0036] - figure 11 and figure 12 show a first variant of the suspension system, according to the invention, in two different operating configurations;

[0037] - figure 13 illustrates a detail of figure 11;

[0038] - figure 14 shows a pair of hydraulic suspensions of the suspension system of figures 11 and 12, according to the invention, hydraulically connected to each other;

[0039] - figure 15 and figure 16 show two different perspective views of a second variant of the suspension system, according to the invention;

[0040] - figure 17 shows a perspective view of a third variant of the suspension system, according to the invention;

[0041] - figures 18 and 19 show two different perspective views of the suspension system of figure 17, with some different components removed.

[0042] DETAILED DESCRIPTION OF THE INVENTION

[0043] With particular reference to the figures, the steerable and tilting suspension system with mechanical support is indicated globally with reference numeral 1. Such suspension system is suitable for use in a vehicle 2 comprising a frame 10 and three or more wheels of which at least a first wheel 11 and a second wheel 12 arranged respectively on opposite sides of the vehicle 2 itself.

[0044] The vehicle 2 can be, for example, a pendulating three-wheeled vehicle, with an endothermic engine, or with an electric motorisation. Alternatively, the vehicle 2 can also be a four-wheeled vehicle, always of the pendulating type.

[0045] The two wheels 11 and 12 placed on the sides of the vehicle 2 can also be offset from each other.

[0046] According to the embodiment illustrated in the accompanying figures, the vehicle 2 is a three-wheeled vehicle, wherein the steerable and swinging wheels are the two front wheels 11 and 12, which are coupled on the same axle (front axle).

[0047] The vehicle 2 is also provided with steering 20 which acts on the steering arms 80.

[0048] The suspension system 1 comprises a pair of hydraulic suspensions 40 having a first end 40a adapted to be hinged to the frame 10 of the vehicle 2, and a second end 40b, opposite to the first end 40a, hinged to a respective support arm 70.

[0049] Each support arm 70 is in turn configured to be hinged to a first end 70a, to the frame 10 of the vehicle 2, and to a second end 70b, opposite to the first end 70a, to a support element 60 respectively of the first wheel 11 and of the second wheel 12, where said support element 60 may be a mechanical spider to which a spindle 50 for supporting the hub of the wheels 11, 12 is constrained.

[0050] According to the invention, the suspension system 1 comprises at least one pair of elastic springs 30 each configured to support a respective support arm 70 and to generate an elastic force in opposition to the force of gravity.

[0051] Advantageously, the elastic springs 30 provide an upward thrust to all the components of the vehicle 2 that are fixed to the support arms 70, namely, first of all, to the hydraulic suspensions 40, but also to the mechanical spiders 60, to the spindles 50, which support the wheels 11 and 12 and ultimately also the wheels 11 and 12 themselves with the relative hubs and brakes.

[0052] Each elastic spring 30 is preferably configured to act between the frame 10 of the vehicle 2 and the support arms 70.

[0053] Preferably, each elastic spring 30 is preloaded, so as to generate a thrust of the entire suspension system 1 upwards and thus be able to support the weight of everything that is connected to the support arms 70 and the hydraulic suspensions 40, in particular when the vehicle 2 is lifted from the ground.

[0054] Preferably each elastic spring 30 is a torsion spring.

[0055] Preferably the axis of the elastic torsion spring 30 is parallel to the axis of rotation of the respective support arm 70 with respect to the frame 10.

[0056] More preferably the elastic torsion springs 30 have the axis of torsion coaxial to the axis of rotation of the respective support arm 70.

[0057] Even more preferably, the elastic torsion springs 30 comprise a first end 30a, configured to be attached to the frame 10 of the vehicle 2, and a second end 30b, opposite to the first end 30a, adapted to support and push the respective support arm 70.

[0058] Advantageously, each elastic torsion spring 30 is fitted on a respective bushing 73, in turn fitted on a hinge element of the support arm 70 to the frame 10 of the vehicle 2.

[0059] Preferably, the elastic spring 30 is fitted on the respective bushing at the portion presenting the coils of the elastic spring 30 itself.

[0060] Preferably, the hinge element comprises a screw 71 and a nut 72 screwable to the end of the screw 71 so that said screw 71 can be fixed to the frame 10 and act as a hinge for the support arm 70. Preferably, as illustrated in the accompanying figures, the bushing 73 can be fitted on the screw 71, preferably at its head end 71a and / or on the screw nut 72.

[0061] As illustrated in the accompanying figures, the screw 71 comprises a head end 71a, which may advantageously have a faceted portion, for example of hexagonal shape. The nut 72 may also have an end 72a having a faceted portion, for example, of hexagonal shape. This faceted portion of hexagonal shape lends itself to being grasped and screwed by means of, for example, suitable wrenches.

[0062] Preferably, the suspension system 1 comprises two pairs of elastic springs 30 positioned symmetrically with respect to the corresponding support arm 70, respectively in a front and rear area of the frame 10. In this way, the elastic springs 30 provide the support arms 70 with an evenly distributed support in the front-rear direction.

[0063] As illustrated in figures 1 to 9, the elastic springs 30 engage with the frame 10 and the support arms 70 in an external position with respect to the support arms 70 themselves. In figures 15 and 16, and 17-19, two variants of the suspension system 1 are shown in which the elastic springs 30 engage with the frame 10 and the support arms 70 in an internal position with respect to the support arms 70 themselves. In fact, the support arms 70 can have a symmetrical configuration defined by a pair of arm elements 79 that are mutually facing and preferably rigidly associated with each other. As shown in figures 15 and 16, and 17-19, the elastic springs 30 can therefore advantageously be arranged between the pairs of arm elements 79, in an internal position with respect to the support arms 70 themselves, and advantageously more protected.

[0064] In the second variant of the suspension system 1, illustrated in figures 15 and 16, the elastic torsion springs 30 are fitted on respective bushings 73, in turn fitted on a hinge element of the support arm 70 to the frame 10 of the vehicle 2, which hinge element however protrudes towards the inside of the two arm elements 79.

[0065] Preferably, according to the second variant of the suspension system 1, illustrated in figures 15 and 16, each elastic spring 30 comprises a pair of first ends 30a, configured to be attached to the frame 10 of the vehicle 2, and a single second end 30b, opposite to the first ends 30a, adapted to support and push the respective support arm 70. Preferably, in fact, each elastic spring 30 comprises two coiled portions, joined together at an elongated spring section 33 that defines the second end 30b, i.e. the end that supports and pushes the respective support arm 70.

[0066] In the third variant of the suspension system 1, illustrated in figures 17-19, the suspension system 1 comprises a pair of elastic springs 30, also of torsional type.

[0067] Each spring 30 comprises a first end 30a, configured to be attached to the frame 10 of the vehicle 2, and a second end 30b, opposite to the first end 30a, adapted to support and push the respective support arm 70.

[0068] Preferably, each spring 30 is respectively associated with the frame 10 and the respective support arm 70 only through its two ends 30a, 30b, i.e. other support and / or guide means are absent. In other words, the variant illustrated in figures 17-19 does not comprise any bushing that rotatably supports at least the coiled portion of the springs 30 themselves.

[0069] Preferably as illustrated in figures 17-19, the first end 30a of the elastic springs 30 is fixed to the support arm 70 by means of a plate 34, screwable to the support arm 70 by means of a pair of screws 35. Preferably, the second end 30b is fixed to a support body 36 of the springs 30, associated with the frame 10 of the vehicle 2. Preferably, a plate 37 is provided that is screwable, by means of a screw 38, to the support body 36 of the springs 30, configured to tighten the end 30b of the springs 30 to the support body 36 itself.

[0070] Preferably, as visible in figure 18, the support body 36 of the springs 30 is rigidly constrained to the frame 10 by means of a bracket 39.

[0071] Advantageously, the absence of constraining elements for the elastic springs 30, and in particular the absence of the bushings 73 inside the coiled portion thereof, allows the springs 30 to twist freely in the space between the arm elements 79, without frictions with such bushings.

[0072] With particular reference to figures 4 and 4a, each hydraulic suspension 40 comprises, inside it, at least one rod-piston group 44. The hydraulic suspensions 40 on the sides of the vehicle 2 are in fluid communication with each other, thanks to flexible fittings 47, by means of a three-way valve 42, where the third way of the valve 42 is in fluid communication with a pressurized tank 41 that takes care of the suspension of the system.

[0073] In particular, a piston 43 configured to separate the pressurized gas present in a first chamber 46 from the oil present in a second chamber 49 flows in said pressurized tank 41, wherein the oil present in the second chamber 49 of the pressurized tank 41 is in fluid communication with the inner part of the valve 42 and, through the flexible fittings 47, with the oil chamber 45 of the hydraulic suspension 40. The second chamber 49 of the pressurized tank 41 defines a variable volume. Furthermore, a spring 48 is configured to progressively manage the bending descent of the vehicle 2, up to the maximum bending angle, as visible in figures 2, 5 and 5 a.

[0074] In this configuration of use of the suspension system 1, an upward movement of the wheel 11 of the vehicle 2 leads to a downward movement of the wheel 12 and vice versa, thanks to the relative displacement of the oil from one side to the other of the hydraulic suspensions 40, in fluid communication with each other through the flexible fittings 47 and the valve 42.

[0075] In another configuration, at rest, the valve 42 is adapted to stop the passage of oil between the hydraulic suspensions 40, thus blocking the relative upward and downward movement of the wheels 11 and 12 of the vehicle 2. This blocking is useful when parking the vehicle 2, as the stability of the vehicle 2 is guaranteed by the closing of the valve 42, allowing the elimination of the traditional stand to park the vehicle 2 in balance.

[0076] Advantageously, the elastic torsion springs 30, suitably preloaded and connected between the frame 10 and the support arm 70, are configured to generate a pressure in the oil chamber 45 of the hydraulic suspension 40, thus preventing a depression in the chamber 45 at the time of a lifting of the vehicle 1 from the road surface, for example in the presence of a jump, a bump or for maintenance needs, when the suspension system 1 has an upward movement, as opposed to the wheels 11, 12, the arms 70 and the other swinging components. This ensures, as mentioned, to avoid the inclusion of air in the oil of the suspension system 1, for example through the chamber 46 and the piston 43. Such air inclusion is in fact unwanted as it makes the suspension system 1 inefficient and / or unusable.

[0077] In addition, the presence of this counter-pressure exerted by the torsion springs 30 in all operating conditions of the vehicle 2 minimises the frictions generated in the hydraulic part of the suspension system 1, with a reduction in construction costs and above all with a reduction in maintenance costs.

[0078] Preferably, the elastic springs 30 can be attached to the frame 10 with their first end 30a at a plurality of points 31, 31’ of attachment to the frame 10, so that by selecting a different attachment point 31 or 31’ it is possible to vary the preload of the elastic spring 30, so that the same suspension system 1 can be used for vehicles 2 with different tracks, such as for example vehicles with a wider track, and with unsprung masses of greater weight.

[0079] Advantageously, the elastic springs 30 can also be of the tensile or compression type, acting between the frame 10 and the support arm 70, or still be constituted by systems of several springs combined.

[0080] Figures 11 to 14 illustrate a variant of the suspension system 1, and in particular of the hydraulic suspensions 40. According to this variant, each hydraulic suspension 40 comprises a rod-piston group 44 movable axially inside a cylinder 400. The piston 44a of the rod-piston group 44 divides the cylinder 400 into an upper chamber 401 and a lower chamber 402, respectively. The cylinder 400 is closed at the bottom by means of a lower cap 104 provided with a seal 107. The rod 44b of the rod-piston group 44 slides axially with respect to this seal 107, which advantageously guarantees the sealing of the lower chamber 402.

[0081] The rod 44b of the rod-piston group 44 has a conduit 103 which extends along the direction of longitudinal development of the rod 44b itself, inside it. This conduit 103 is configured to put the internal volume of the cylinder 400 and the environment external to the cylinder 400 in fluid communication. In particular, the conduit 103 is configured to put the internal volume of the lower chamber 402 of the cylinder 400 in fluid communication with the external environment.

[0082] Preferably, the rod 44b further comprises at least one lateral hole 102 configured to put the conduit 103 in fluid communication with the lower chamber 402 of the cylinder 400.

[0083] The at least one lateral hole 102 is therefore made in a rod portion 44b which, in any position of the rod-piston group 44 with respect to the cylinder 400, is always arranged inside the cylinder 400. As illustrated in figures 11 to 14, for example, the lateral hole 102 is formed in the rod 44b in proximity to the piston 44a. In this way, even in the case of maximum extension of the rod-piston group 44 from the cylinder 400, as illustrated in figure 12, the lateral hole 102 remains inside the lower chamber 402 of the cylinder 400.

[0084] Preferably, the rod 44b further comprises a one-way valve 101 configured to put the conduit 103 in fluid communication with the external environment.

[0085] The directional valve 101 is therefore made of a rod portion 44b which, in each position of the rod-piston group 44 with respect to the cylinder 400, is always arranged outside the cylinder 400. As illustrated in figures 11 to 14, for example, the one-way valve 101 is positioned in the rod 44b near its end 40b. In this way, even in the case of maximum retraction of the rodpiston group 44 in the cylinder 400, as illustrated in figure 11, the one-way valve 101 remains outside the cylinder 400, facing the external environment.

[0086] Substantially therefore, the internal volume of the lower chamber 402 of the cylinder 400 can be put in fluid communication with the environment external to the cylinder 400, by means of the at least one lateral hole 102, the conduit 103 and the one-way valve 101.

[0087] The downward movement of the rod 44b allows the air present inside the lower chamber 402 of the cylinder 400 to escape, through, in sequence, the lateral hole 102, the longitudinal conduit 103 and the one-way valve 101, which allows the passage of air only in the exit direction.

[0088] When the rod 44b moves in the opposite direction, upwards, the entry of air into the conduit 103 is instead not allowed, due to the presence of the one-way valve 101. This prevents dirt or other external agents from being able to invade the volume within the lower chamber 402 of the cylinder 400.

[0089] Similarly, the presence of the seal 107 also prevents dirt or other external agents from penetrating into the lower chamber 402 of the cylinder 400.

[0090] Furthermore, since the fluid present in the lower chamber 402 of the cylinder 400 is not subject to high pressures, even the seal 107 itself is not subject to stresses deriving from high pressures, and therefore the good operation of the hydraulic suspension 40 is not significantly disrupted by frictions at the sliding area of the rod 44b with respect to the seal 107.

[0091] Preferably, a sufficient amount of oil is present in the lower chamber 402 of the cylinder 400 to keep the seal 107 and the sliding surface of the rod 44b itself lubricated.

[0092] Preferably, as illustrated in figure 12, the at least one lateral hole 102 is made, along the rod 44b, at a height such that in the case of maximum extension of the hydraulic suspension 40, said lateral hole 102 is arranged at a minimum distance from the bottom of the cylinder 400, i.e. from the lower cap 104.

[0093] In this way, the amount of oil present in the lower chamber 402 of the cylinder 400 does not escape through the lateral hole 102 and the conduit 103 leading to the one-way valve 101, since even in the case of maximum extension of the suspension 40, this hole 102 remains at a higher level than the level of the oil present in the lower chamber 402.

[0094] Each hydraulic suspension 40 may comprise a respective one-way valve 101.

[0095] Alternatively, as illustrated in figure 14, a pair of hydraulic suspensions 40 may comprise a single one-way valve 101 applied to the conduit 103 of the rod 44b of the rod-piston group 44 of a first hydraulic suspension 40. The conduit 103 of the rod 44b of the rod-piston group 44 of the second hydraulic suspension 40 is in fluid communication with the conduit 103 of the first hydraulic suspension 40 via a further conduit 109. This further conduit 109 may advantageously be constituted by a hose.

[0096] The operation of the suspension system 1 according to the variant of figure 14 described above, with a single one-way valve 101, is analogous to that described above with reference to the embodiment having a one-way valve 101 for each hydraulic suspension 40.

[0097] In addition, the present invention also concerns a method for preloading the elastic springs 30, comprising the steps of: a. Having a suspension system 1 as described above; b. Having a special key 90 for the preloading, comprising a gripping lever 91, comprising an end 92 fittable around the elastic spring 30 and comprising in turn a protrusion 92, configured to engage with the first end 30a of the elastic spring 30; c. positioning said end 92 of the special key 90 around the elastic spring 30; d. rotating said special key 90, thereby bringing said first end 30a of the elastic spring 30 at one of the points 31, 31’ of attachment to the frame 10 selected according to the desired degree of preload; e. removing the special key 90 from the elastic spring 30. In this way, the elastic spring 30 is properly loaded and attached to the frame 10.

[0098] More in particular, the end 92 of the special preloading key 90 is defined by a hollow structure that is adapted to embrace the elastic spring 30, in particular the coils of the elastic spring 30 at the hinge element of the support arm 70 to the frame 10, namely the screw 71. In this position, the protrusion 93, preferably obtained at the aforementioned hollow structure, engages with the first end 30a of the elastic spring 30 so as to rotate it around the hinge element.

[0099] The rotation of the special key 90 thus causes the elastic spring 30 to wind around the hinge element, loading itself, until it reaches one of the points 31, 31’ of attachment of the first end 30a of the spring 30 to the frame 10.

[0100] The fact of arranging on the frame 10 several attachment points 31, 31’ at different angular distances allows to be able to attach the first end 30a of the spring 30 in different positions, to which different degrees of preloading of the elastic spring 30 itself correspond. Two different spring preload configurations 30 are illustrated respectively in figures 10, 10a. In particular, in the configuration of figure 10 the ends 30a of the springs 30 are fixed to a first attachment point 31, while in the configuration of figure 10a the ends 30a of the springs 30 are fixed to a second attachment point 31 ’ angularly spaced by about 90° with respect to the first attachment point 31.

[0101] In practice, it has been found how the suspension system, according to the present invention, fulfils the task as well as the intended purposes as it allows to make the driving of the vehicle safer and more comfortable.

[0102] Another advantage of the suspension system, according to the invention, consists in the fact of avoiding the inclusion of air in the oil and decreasing the frictions inside the chambers of the hydraulic suspension system, leading to a better efficiency of the system, drastically reducing the maintenance phases.

[0103] Furthermore, all the details can be replaced by other technically equivalent elements. In practice, any materials can be used according to requirements, as long as they are compatible with the specific use, the dimensions and the contingent shapes.

Claims

CLAIMS1. A steerable and tilting suspension system (1) with mechanical support, for a vehicle (2) comprising a frame (10) and three or more wheels of which at least a first wheel (11) and a second wheel (12) are respectively arranged on opposite sides of said vehicle (2), said suspension system (1) comprising a pair of hydraulic suspensions (40) having a first end (40a) adapted to be hinged to said frame (10) and a second end (40b), opposite to said first end (40a), hinged to a respective support arm (70), each support arm (70) being configured to be hinged, at a first end (70a), to said frame (10) and at a second end (70b), opposite to said first end (70a), to a support element (60) of, respectively, said first wheel (11) and said second wheel (12), characterized by comprising at least one pair of elastic springs (30) each configured to support a respective support arm (70) generating an elastic force in opposition to the force of gravity.

2. Suspension system (1), according to the preceding claim, wherein each elastic spring (30) is configured to operate between said frame (10) and said support arm (70).

3. Suspension system (1), according to one or more of the preceding claims, wherein each elastic spring (30) is preloaded.

4. Suspension system (1), according to one or more of the preceding claims, wherein each elastic spring (30) is a torsion spring with an axis parallel, preferably coaxial, to the axis of rotation of the respective support arm (70) about said frame (10).

5. Suspension system (1) according to one or more of the preceding claims, wherein each elastic spring (30) is a torsion spring comprising a first end (30a) configured to be attached to said frame (10) and a second end (30b), opposite to said first end (30a), adapted to support and push said respective support arm (70).

6. Suspension system (1), according to one or more of the preceding claims, wherein each elastic spring (30) is fitted on a respective bushing (73), wherein said bushing (73) is fitted on a hinge element of said support arm (70) with respect to said frame (10).

7. Suspension system (1), according to the preceding claim, wherein said hinge element comprises a screw (71) and a nut (72) screwable on said screw (71), said bushing (73) being fitted on said screw (71) and / or on said screwable nut (72).

8. Suspension system (1), according to one or more of the preceding claims, comprising a pair of elastic springs (30) positioned symmetrically with respect to a corresponding support arm (70) in a front and in a rear area of said frame (10), respectively.

9. Suspension system (1) according to one or more of the preceding claims, wherein said first end (30a) of each elastic spring (30) is configured to be engageable to a plurality ofpoints (31) of attachment to said frame (10), so as to vary the preload of each elastic spring (30).

10. Suspension system (1), according to one or more of the preceding claims, wherein each of said hydraulic suspensions (40) comprises a rod-piston group (44) movable axially inside a cylinder (400), the rod (44b) of said rod-piston group (44) comprising a conduit (103) which extends along the direction of longitudinal development of said rod (44b) and inside said rod (44b), said conduit (103) being configured to put the internal volume of said cylinder (400) in fluid communication with the environment external to said cylinder (400).

11. Suspension system (1), according to claim 10, wherein said rod (44b) comprises at least one lateral hole (102) configured to put said conduit (103) in fluid communication with a chamber (402) of said cylinder (400).

12. Suspension system (1), according to claim 10 or 11, wherein said rod (44b) comprises a one-way valve (101) configured to put said conduit (103) in fluid communication with the environment external to said cylinder (400).

13. Suspension system (1), according to claim 12, wherein said pair of hydraulic suspensions (40) comprises a single one-way valve (101) configured to put the conduit (103) of a first rod (44b) of a rod-piston group (44) of a first hydraulic suspension (40) in fluid communication with the environment external to said cylinder (400) of said first hydraulic suspension (40), and a further conduit (109) configured to put said conduit (103) of said first rod (44b) of said first hydraulic suspension (40) in fluid communication with the conduit (103) of a second rod (44b) of a second hydraulic suspension (40).

14. Suspension system (1), according to claim 1, 2 or 3, wherein each elastic spring (30) is a tension or compression spring acting between said frame (10) and said support arm (70).

15. Method for preloading an elastic spring (30) of a suspension system (1) according to one or more of claims 1 to 13, comprising the following steps: a. Having a suspension system (1) according to one or more of claims 1 to 13; b. Having a special key (90) for the preloading, comprising a gripping lever (91), comprising an end (92) fittable around said elastic spring (30) and comprising in turn a protrusion (93), configured to engage with said first end (30a) of said elastic spring (30); c. positioning said end (92) of said special key (90) around said elastic spring (30);d. rotating said special key (90), thereby bringing said first end (30a) of said elastic spring (30) at one of the points (31) of attachment to said frame (10), selected according to the desired degree of preload; e. removing said special key (90) from said elastic spring (30), said elastic spring (30) being thus properly loaded and engaged to said frame (10).

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