[001 ] The present invention relates to an independent front suspension for application on motor vehicles, particularly commercial vehicles like trucks and buses, which promotes non-reactive kinematics to the momentum generated on the running assembly, specifically when applied to braking, improving the stability of the vehicle and the comfort of the user.

Description of the prior art

[002] Automobile suspensions are component assemblies that act so as to absorb stresses coming from the vehicle base and to improve the capability of the vehicle to adhere to the ground. Suspensions are extremely important elements of the construction of an automobile, since they provide stability and comfort in driving, while reducing the intensify of impacts that might damage other elements that constitute a car, among other advantages.

[003] Among the various concepts of known constructive embodiments for existing suspensions, the "Double Wishbone" or "doubie-A suspension" stands out for enabling a wider range of possibilities for fine adjustment of the suspension, so as to make it particularly efficient for a determined specific application. This flexibility aggregated to a double-wishbone design has caused it to become quite popular for applications on high-performance vehicles, or vehicles that need specific parameters for their suspensions.

[004] A double-wishbone suspension comprises, in general, two wishbone-shaped elements, that is, elements that have a double end and a single one, which are associated to both a vehicle substructure (from its double end) and the wheel (by means of its single end). These wishbones are associated in a way that allows free vertical movement, generally by means of a concentric association of a bearing to a horizontally positioned axle. Halfway across the double ends of the wishbone, a cylindrical shock absorber is arranged, generally accompanied by a helical spring.

[005] The free horizontal movement of the wishbones added to the shock-absorber guarantees efficient impact absorption, while keeping assembly stability, especially by employing a stabilization rod that promotes more reliable association between the lower wishbone and the vehicle substructure,

[006] Although a double-wishbone suspension has advantages with regard to design flexibility, the embodiment in which it is presented today brings problems with respect to kinematics in braking the vehicle. More specifically, the braking condition leads to a directional tendency of the vehicle, generally undesired, which causes the drive to have difficulty in recovering control. This is especially perceptible in (panic) sudden braking conditions, in which the loss of direction caused by braking often causes serious accidents.

[007] Car suspensions play an important role in keeping control over the car in braking situations, since they are directly associated to the wheels. However, the prior art still does not comprise a double-wishbone suspension whose constructive configuration promotes kinematics that is resistant (non- reactive kinematics) to the moment generated by the wheel assembly while braking. This fact is particularly visible on commercial vehicles such as trucks and buses, the braking stresses of which are substantially greater than on touring cars, for example, chiefly when it comes to panic braking.

Objectives of the invention

[008] In view of the problems presented by the prior art, the present invention has the objective of providing a double-wishbone suspension that does not have reactive behavior when braking the vehicle, thus providing better comfort and control to the user.

Brief description of the invention

[009] The present invention relates to an independent front suspension for application on commercial vehicles, such as trucks and buses, comprising a substructure associated to an upper wishbone and a lower wishbone. The upper and lower wishbones are both associate to a wheel and configuring a caster angle, a camber angle and a toe angle, wherein the caster angle (40) is of 4.7° to 5.3°, the camber angle (50) is of -0,3° to 0.3°, and the toe angle (82) is of -0,85° to 1 .15° [0010] Further, the present suspension comprises a shock-absorber provided with a first end associated to the substructure and a second end associated to the lower wishbone.

Brief description of the drawings

[001 1 ] The present invention will now be described in greater detail with reference to an embodiment example represented in the drawings. The figures show:

[0012] Figure 1 - a schematic drawing of a front detail of a wishbone suspension, highlighting the camber angle;

[0013] Figure 2 - a schematic drawing of a side detail of a vehicle highlighting the caster angle;

[0014] Figure 3 - a schematic drawing of a front upper detail of a vehicle highlighting the toe angles;

[0015] Figure 4 - a perspective view of the suspension of the present invention applied to a vehicle;

[0016] Figure 5 - a front view of a detail of the suspension of the present invention applied to a vehicle;

[0017] Figure 8 - a side view of a detail of the suspension of the present invention applied to a vehicle; and

[0018] Figure 7 - a front top view of a detail of the suspension of the present invention applied to a vehicle.

Detailed description of the figures

[0019] For better clarification of the present invention, from figures 1 , 2, and 3, one will clarify the definition of the camber, caster and toe angles of any wishbone suspension. The elements illustrated in figures 1 , 2 and 3 are schemes representative of the concept of wishbone suspension.

[0020] Figure 1 shows a front detail of a vehicle provided with a wishbone suspension. Said suspension 10A nis associated to a vehicle wheel 200A of the vehicle. One represents schematically the upper and lower wishbones 1 1 A, 12A, and the angulations resulting from the positioning and construction of said wishbones. [0021 ] More specifically, the wishbones 1 1A, 12A comprise, at their ends associated to the wheel, a joint 1 12A, 122A, which in turn is associated to the wheel 200A. The camber angle 50A is formed by the inclination of the wheel 200A of the vehicle and a reference line perpendicular to the ground, having as reference a plane perpendicular to the longitudinal direction of the vehicle, as shown in figure 1. It should be further noted that the wheel angulation is proportional to the angle formed by the joints 1 12A, 122A of the wishbones on a plane perpendicular to the longitudinal direction of the vehicle, also shown in figure 1 .

[0022] The camber angle 50A is, in short, responsible for stability of the vehicle when a turn is made. In other words, it is responsible for the control of the user over the vehicle when making a turn. Thus, just as the caster angle 40A, the camber angle 50A is also extremely important to obtain a desirable braking condition on commercial vehicles. A desirable camber angle for this type of situation according to the present invention will be presented later.

[0023] On the other hand, the caster angle 40A is the angle formed between the line that passes through the center of the joints 1 10A, 120A and a reference line perpendicular to the ground, having as a reference a plane parallel to the longitudinal direction of the vehicle, as shown in figure 2.

[0024] The caster angle 40A is, in short, responsible for the capability of self-correction of the direction of the vehicle wheel when the later makes a turn, and therefore it is an extremely important parameter for stability of the vehicle, chiefly in braking conditions. Thus, the definition of a desirable caster angle for commercial vehicles and for panic braking conditions is proposed by the present invention, as will be established later.

[0025] Figure 3 shows a top view of the front part of the vehicle. One defines a first distance 80A between the front parts of the wheels 200A and a second distance 61 A between the back parts of the wheels 200A. The difference between the first and the second distances 60A, 61 A is usually called "toe", and is a parameter that influences the stability of the vehicle in straight line. Again, this parameter, and more specifically the toe angle 62A formed by the difference between the "toe" distances, will be exploited by the present invention for a braking situation on commercial vehicles, as will be clarified later,

[0026] Once the relationships of the camber, caster and toe angles to the stability provided to the vehicle have been clarified, figure 4 shows a wishbone suspension as proposed by the present invention. It shows a substructure 30 that comprises, associated to it, an upper wishbone, and a lower wishbone 12. Each wishbone is provided with a single end 1 10, 120 and a double end 1 1 1 , 121 , wherein the double end 1 1 1 , 121 is associated to the substructure and the single end 1 10, 120 is provided with a joint 1 12, 122 for association to a vehicle wheel 200.

[0027] The substructure 30 is also associated to a shock-absorber 20, the latter being preferably a hydraulic shock-absorber provided with a helical spring. The shock-absorber is associated, in turn, to the lower wishbone 12 adjacent to its single end 120, close to the joint 122. Moreover, the suspension also comprises an steering shaft 70.

[0028] As already clarified, the caster and camber angles of a suspension are determined by the positioning of the upper and lower wishbones 1 1 , 12, and the angle that both of the form with respect to a plane that is longitudinally parallel and perpendicular to the vehicle, respectively.

[0029] More specifically, the caster angle 40 and the angle formed by a line that passes through the joints 1 12, 122 and a line perpendicular to the ground A, both lines contained located on a plane parallel to the longitudinal direction of the vehicle, as shown in figure 6. On the other hand, the camber angle 50 is proportional to the angle formed by a line that passes through the center of the joints 1 12, 122 and a line perpendicular to the ground B, both lines located on a plane perpendicular to the longitudinal direction of the vehicle, as shown in figure 5. Finally, the toe angle is defined by the line formed by the difference between the toe distances 60, 61 and a line longitudinal to the vehicle C, as shown in figure 7.

[0030] By making use of the great flexibility provided by the double- wishbone suspension for adjustments of constructive embodiment, the present invention proposes intervals of cater, camber and toe angles, which result in a suspension for commercial vehicles that does not react excessively to the sudden braking stresses, enabling better control and better stability in the vehicle direction,

[0031 ] In this regard, according to the present invention, the caster angels are of 4.7° to 5.3°, the camber angles are of -0.3° to 0.3°, and the toe angles are of -0.85° to 1 .15°. It should be noted that the positive and negative values angle values are function of the reference line used in obtaining each angle, wherein for the caster angles 40, camber angels 50 and toe angles 62, the angle of 0° is defined by the lines Y, Z and W, respectively.

[0032] In order to obtain these desirable angles for the braking situations on commercial vehicles, one presents hereinafter a preferred embodiment of the present invention, which promotes a particularly efficient construction of a wishbone suspension. More specifically, this particular construction comprises a series of specific coordinates of the suspension elements that generate the desirable camber, caster and toe angles, as will be clarified hereinafter.

[0033] The coordinates that define the non-reactive behavior of the suspension of the present invention are those that define the ends of the upper and lower wishbones 1 1 , 12 (for caster and camber angles) and those that define the ends of the steering shaft 70 (for the toe distances).

[0034] The center of the single end 1 10 of the upper wishbone 1 10 comprises a coordinate 90, while the center of each tip of the double end 1 1 1 (left and right, respectively, taking the direction from outside to inside of the vehicle) comprises coordinates 91 , 92. Similarly, the center of the single end 120 of the lower wishbone 12 comprises a coordinate 93, while the center of each tip of the double end 121 (left and right, respectively, taking the direction from the outside to the inside of the vehicle) comprises coordinates 94, 95.

[0035] On the other hand, the steering shaft 70 is provided with an inner end 71 and an outer end 72 (relating to the inside and the outside of the vehicle, as shown in figure 5), each end 71 , 72 comprising coordinates 96, 97, respectively. [0036] Once the coordinates that enable the non-reactive behavior proposed by the present invention in this preferred embodiment are defined, one presents hereinafter a table that specifies each coordinate with respect to the axes X, Y and Z, as shown in figure 4. The axes X and Z are referenced (value = 0) in the center of the vehicle rule, while the axis Y is referenced in the center of the vehicle wheel, which the axis Y is referenced

(value =0) in the center of the substructure 30.

Once the above table has been presented, one understands that the caster, camber and toe angles of this preferred embodiment are obtainable by using the above coordinates, thus determining a suspension construction that is not reactive to the stresses underdone while braking commercial vehicles.

[0038] It is important to note that, although one has presented a preferred embodiment that makes use of a group of specific coordinates to obtain the proposed suspension, it would be evident to a person skilled in the art that other constructive embodiments (and, as a result, other coordinates) might be used to achieve the same interval of desirable caster, camber and toe angles for a suspension that is not reactive to the braking of commercial vehicles.

[0039] A preferred example of embodiment having been described, one should understand that the scope of the present invention embraces other possible variations, being limited only by the contents of the accompanying claims, which include the possible equivalents.