Road vehicle comprising a suspension unit configured to vary the camber angle and the toe angle of the front wheels

Abstract

To provide an innovative active camber unit capable of changing not only a camber angle but also a toe-in angle.SOLUTION: A road vehicle 1 having a roll axis X, a pitch axis Y and a yaw axis Z and comprising a fixed chassis 2 and two front wheels, a suspension assembly 4 being provided for each front wheel and being arranged between the fixed chassis and the corresponding front wheel, each suspension assembly comprising an upper lever and a rod, the upper lever being an active tie rod for varying the camber angle of the corresponding front wheel; The other rod is a fixed tie rod for varying the toe-in angle of the corresponding front wheel and the active camber tie rod is a telescopic tie rod, the active camber tie rod and the fixed toe-in tie rod being connected on one side to the chassis and on the other side to the wheel at a point in space such that actuating the active tie rod modifies both the camber angle and the toe-in angle simultaneously.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] Cross-reference to related patent applications This patent application claims priority from Italian Patent Application No. 102024000013825, filed June 17, 2024, the contents of which are incorporated herein by reference.

[0002] The technical field to which the present invention is directed is that relating to road vehicles, and in particular to sports cars. In this context, the invention addresses the problem of creating a suspension assembly adapted to act on the front wheels to vary not only the camber angle but also the toe angle, which reduces the number of active parts in the assembly. [Background technology]

[0003] As is well known, the dynamics of road vehicles, particularly automobiles, are defined by three axes: the roll axis, the pitch axis, and the yaw axis. The roll axis identifies the forward direction of the vehicle, the yaw axis is an axis perpendicular to the plane in which the vehicle is moving forward (if the plane is horizontal, the axis corresponds to the direction of gravity), and the pitch axis is an axis perpendicular to the two previous axes. As is well known, a road vehicle includes a fixed chassis and four wheels. The wheels rest on the floor, while the chassis is connected to the wheels by a suspension. It is known to provide a steering assembly for at least each front wheel, i.e., a set of elements arranged between the fixed chassis and the corresponding front wheel, configured to change the position of the wheel relative to the chassis. In particular, it is necessary to be able to rotate the wheel along an axis parallel to the yaw axis (i.e., the vertical line) so that an angle can be created between the wheel and the roll axis. This angle is known as the toe-in angle, and it is this change in angle that allows the vehicle to navigate curves. It is also known that a steering unit can change the angle of the wheel by rotating it along an axis parallel to the roll axis. This rotation creates a deviation between the wheel and the vertical yaw axis known as the camber angle, which also plays a role in the vehicle's dynamics in curves (an effect that is highly exploited in the bicycle field).To change the toe-in angle, a toe-in tie rod is now provided, which is connected to an arm connected to the chassis on one side and to the wheel on the other side, and which is of the telescopic type (operated by the vehicle's handlebars).A more recent possible active change of the camber angle is the provision of a camber tie rod, which is also of the telescopic type, connected to an arm connected to the chassis on one side and to the wheel on the other side.The movement of this camber tie rod is managed by a special electronic control. Summary of the Invention [Problem to be solved by the invention]

[0004] Based on this prior art, the object of the present invention is to make available an innovative active camber unit that can vary not only the camber angle but also the toe-in angle, which is an alternative to the prior art and has fewer active elements. [Means for solving the problem]

[0005] According to the present invention, an innovative camber unit for road vehicles is therefore proposed. The starting point of the present invention is therefore a road vehicle with a roll axis X, a pitch axis Y, and a yaw axis Z. Those skilled in the art are familiar with these angles. The vehicle includes a fixed chassis and two front wheels. For each front wheel, there is a suspension assembly connecting the fixed chassis to the corresponding front wheel. Each of these suspension assemblies includes an upper rod and lever, and two lower rods (schematically represented in the figures as four arms connected at the center of the wheel) connected on one side to the fixed chassis and on the other to the wheel hub carrier. According to a main aspect of the present invention, only the upper suspension lever is realized in the form of a telescopic active tie rod whose length can be changed, while the other upper rod is realized in the form of a fixed-length tie rod. As will also be shown in the example shown in the figures, according to the present invention, the active tie rod can be defined as a camber tie rod, since changing its length changes the camber angle of the wheel. As the camber angle changes, the other fixed tie rod imparts a toe-in angle to the wheel, and so may be defined as a toe-in tie rod. Therefore, actuating the camber tie rod to modify the camber angle automatically causes a corresponding change in the toe-in angle. Depending on the required design, by varying the spatial location of the connection points of the suspension's upper levers and rods relative to the chassis and wheel, various percentages of toe-in and camber angles can be achieved for the same camber angle imparted by the active lever.

[0006] Further features of the invention are defined in the accompanying dependent claims.

[0007] In order that the present invention may be better understood, preferred embodiments thereof will now be described, by way of example only and not by way of limitation, with reference to the accompanying drawings, in which: [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a schematic diagram of the vehicle components involved in the present invention, with the remaining vehicle components not shown for clarity; FIG. [Figure 2] 2 is a view of the wheel of FIG. 1 with a corresponding suspension assembly according to the present invention; [Figure 3] FIG. 3 is a top view (along yaw axis Z) of the suspension assembly of FIG. 2, with the wheels shown transparent for clarity. [Figure 4] FIG. 3 is a side view (along pitch axis Y, from the outside towards the center of the vehicle) of the suspension assembly of FIG. 2, with the wheels shown transparent for clarity. [Figure 5] FIG. 1 is a diagram of one of the various wheel state positions achieved by operating the camber tie rod (the only active lever of the suspension assembly), in a neutral configuration. [Figure 6] FIG. 1 is a diagram of one of the various wheel state positions achieved by operating the camber tie rod (the only active lever in the suspension assembly), showing how a given camber angle creates a resulting toe-in angle. [Figure 7] FIG. 1 is a diagram of one of the various wheel state positions achieved by operating the camber tie rod (the only active lever in the suspension assembly), showing how a given camber angle creates a resulting toe-in angle. DETAILED DESCRIPTION OF THE INVENTION

[0009] FIG. 1 is a schematic diagram of vehicle components involved in an embodiment of the present invention. For clarity, the remaining vehicle components are not shown. Specifically, FIG. 1 shows a vehicle 1 with a fixed chassis 2 and front wheels 3. As with any road vehicle, the mechanics of the vehicle 1 are defined by three axes X, Y, and Z passing through its center of gravity, known as the roll axis X, pitch axis Y, and yaw axis Z. Those skilled in the art will be familiar with these axes. Reference number 4 in FIG. 1 identifies the suspension assembly of the front wheels 3, with an upper lever and rod and two lower rods relative to the center of the wheels. Arrow F identifies the forward direction (opposite to the reverse direction). Arrows III and IV identify the viewing directions in FIGS. 3 and 4.

[0010] Figure 2 is a diagram of the wheel 3 of Figure 1 with a corresponding suspension assembly 4. This suspension assembly 4 according to the invention comprises an upper lever 5 and upper rod 6, and two lower rods 10, 11. The upper lever is realized in the form of an active tie rod 5, which is configured to vary the camber angle of the front wheel 3. The remaining upper rods 6 are fixed tie rods 6, which are configured to vary the toe-in angle of the corresponding front wheel 3 during actuation of the active tie rod 5. Thus, only the camber tie rod 5 is an active telescopic tie rod that varies its length between end 7 and end 12 (perpendicular to the rotation axis connecting the lever 5 to the chassis), while the toe-in tie rod 6 is a fixed-length tie rod between end 8 and end 13. The toe-in tie rod 6 and the camber tie rod 5 are connected on one side to the chassis 2 (the ends of the two connection points of the lever end 13) and on the other side (ends 7 and 8) to a hub carrier integral with the wheel, which is diagrammatically provided with arms 14, 15 connected to the centre 9 of the wheel. According to the general definition of the invention, the attachment points of the above-mentioned toe-in tie rod 6 and camber tie rod 5 to the chassis 2 and to the wheel 3 are such that actuating the camber tie rod 5 creates a camber angle and the fixed tie rod 6 creates a corresponding toe-in angle.

[0011] 3 and 4 are respectively a top view (along the yaw axis Z) and a side view (along the pitch axis Y) of the suspension assembly of FIG. 2 along the arrows labeled III and IV in FIG. 1, with the wheels shown transparent for clarity. These views make it clear how, in this example, the attachment points 7 and 8 of the upper lever 5 and upper rod 6 are spatially positioned relative to the wheel hub carrier, which is diagrammed with the suspension arm centered at the center of the wheel. It can be noted that in this example, in a zero toe-in and camber angle configuration, the wheel-side end 7 of the lever with the active camber tie rod 5 is outboard of or substantially aligned with the wheel-side end 8 of the fixed toe-in tie rod 6 along a direction parallel to the pitch axis Y. FIG. 3 also makes it possible to see that, in this example, the end 7 of the active camber lever or tie rod 5 is beyond the wheel center along the forward direction F, while the wheel-side end 8 of the fixed toe-in tie rod 6 is behind the wheel center along the forward direction F. Furthermore, in this example, the inboard end 13 of the fixed toe-in tie rod 6 is substantially aligned with the wheel center along axis Y.

[0012] It can be noted in FIG. 4 that in a zero toe-in and camber angle configuration, the wheel-side end 7 of the lever carrying the active camber tie rod 5 is located further forward than the wheel-side end 8 of the toe-in tie rod 6 along a direction parallel to the roll axis X. Specifically, if one views the wheel from outside the vehicle along direction Y and divides the wheel into four quarters (labeled I-II-III-IV in FIG. 4), the wheel-side end 7 of the active camber tie rod 5 is in quarter II (from the front F, above and to the left of the wheel center), while the end 8 of the toe-in tie rod 6 is in quarter I (from the front F, above and to the right of the wheel center). With respect to a vertical line Z passing through the wheel center, points 7 and 8 identify alpha and beta angles of 0° to 10° and 10° to 25° on either side within quarters II and I, respectively. In this example, in a zero toe-in and camber angle configuration, the wheel end 8 of the toe-in tie rod 6 is higher than the wheel end 7 of the camber tie rod 5 along a direction parallel to the yaw axis Z, or they are both at substantially the same height. As can be seen, the wheel ends 7, 8 of the tie rods 5, 6 are located above the centers 9 of the wheels 3 in quarters II and I.

[0013] Finally, Figures 5-7 show various wheel positions achieved by operating the camber tie rod 5 (the only active tie rod in the unit) from a neutral position. It can be noted in Figures 6 and 7 that a given camber angle creates a resulting toe-in angle.

[0014] It is clear that changes and variations may be made to the embodiments just described and shown in this specification without thereby departing from the scope of protection of the invention as defined in the appended claims. [Explanation of symbols]

[0015] 1 vehicle 2 Fixed chassis 3 Front wheels 4. Suspension Assembly 5 Upper lever, active camber tie rod 6 Upper rod, fixed toe-in tie rod 7 end, mounting point, end (of camber tie rod 5), wheel-side end (of lever) 8 end, attachment point, end (of toe-in tie rod 6), wheel side end 9 (Wheel) Center 10, 11 Lower rod 12 End 13 end, lever end, inner end (of fixed toe-in tie rod 6) 14, 15 Arms I, II, III, IV Quarters III Arrow, observation direction in Fig. 3 IV Arrow, observation direction in Fig. 4 F arrow, forward, front X Roll Axis Y pitch axis Z yaw axis, vertical line

Claims

1. 1. A road vehicle (1) having a roll axis (X), a pitch axis (Y) and a yaw axis (Z) and comprising a fixed chassis (2) and two front wheels (3), each front wheel being provided with a suspension assembly (4) arranged between the fixed chassis (2) and the corresponding front wheel (3), each suspension assembly (4) comprising an upper lever and a rod, the upper lever being realized in the form of an active tie rod (5) configured to vary the camber angle of the corresponding front wheel (3), the rod being realized in the form of a fixed tie rod (6) configured to vary the toe angle of the corresponding front wheel (3), the active camber rod (5) being an extendable rod in order to vary its length, the active camber rod (6) and the fixed toe-in rod (5) being connected on one side to the chassis and on the other side to the wheel at a point in space such that actuation of the active rod simultaneously modifies both the camber angle and the toe-in angle.

2. 2. The road vehicle (1) of claim 1, wherein the active camber tie rod (5) and the fixed toe tie rod (6) each include a wheel-side end (7, 8) connected to a hub carrier, and in a zero toe and camber angle configuration, the wheel-side end (7) of the fixed camber tie rod (5) is at or substantially aligned with the wheel-side end (8) of the toe-in tie rod (6) at its outermost position along a direction parallel to the pitch axis (Y).

3. 3. A road vehicle (1) according to claim 2, wherein in the zero toe and camber angle configuration, the wheel-side end (7) of the active camber tie rod (5) is located forward of the wheel-side end (8) of the toe tie rod (6) along a direction parallel to the roll axis (X).

4. 4. A road vehicle (1) according to claim 3, wherein, along the direction parallel to the roll axis (X), the wheel-side ends (7, 8) of the tie rods (5, 6) are on either side of the center (9) of the wheel (3), the wheel-side end (7) of the camber tie rod (5) is downstream of the center (9) of the wheel (3), the wheel-side end (8) of the toe-in tie rod (6) is upstream of the center (9) of the wheel (3), and both wheel-side ends (7, 8) are above the center (9) of the wheel (3).

5. 5. The road vehicle (1) of claim 4, wherein in the zero toe-in and camber angle configuration, the wheel-side attachment points of the active camber tie rod and the toe tie rod specify opposing angles relative to a vertical line passing through the wheel center between 0° and 10° and between 10° and 25°.

6. 6. A road vehicle (1) according to claim 4 or 5, wherein in the zero toe and camber angle configuration, the wheel-side ends (8) of the toe-in tie rods (6) are higher along a direction parallel to the yaw axis (Z) or substantially aligned along the pitch direction (Z) than the wheel-side ends (7) of the camber tie rods (5).

7. 7. A road vehicle (1) according to any one of claims 1 to 6, wherein the wheel-side ends (7, 8) of the tie rods (5, 6) are arranged to obtain a toe angle to camber angle ratio ranging from a minimum of -3 to a maximum of -5.5, achieving toe angles and camber angles of opposite signs.

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