Mcpherson-type suspension assembly

Abstract

A McPherson-type suspension assembly comprising: a steering knuckle (2) configured to carry a wheel hub; a lower arm (4) provided with a first end (4-a) connected to the steering knuckle (2) and a second end (4-b) connected to the body of a vehicle; an actuating arm (6) provided with a first end portion (6-a) connected to a steering box tie rod (7) by means of a first joint with the possibility of rotation about a first axis H; the actuating arm (6) has a second end portion (6-b) hinged to the steering knuckle by means of a second joint with the possibility of rotation about a second axis (K); an upper arm (10) provided with a first end (10-a) hinged to the body and a second end (10-b) connected to an intermediate portion of the actuating arm (6) by means of a third joint configured to effect the rotation of the actuating arm about a third axis L of rotation. An adjustment device (15) is provided, configured to move, following an adjustment command, the third joint with respect to the actuating arm and to vary the distance H-L between the first axis H and the third axis L and the distance between the second axis K and the third axis L.

Description

[0001] DESCRIPTION of the patent for industrial invention entitled:

[0002] “MCPHERSON-TYPE SUSPENSION ASSEMBLY”

[0003] BACKGROUND OF THE INVENTION

[0004] As is known, McPherson suspensions, thanks to their simplicity and effectiveness, have become definitively established since the 1970s, and today are almost universally used on passenger cars and light commercial vehicles, particularly for front suspensions.

[0005] A McPherson-type suspension assembly generally comprises: a steering knuckle configured to carry a wheel hub; a lower arm connected to the steering knuckle and to the body of a vehicle; an upper arm connected to the vehicle body and an actuating arm which effects the rotation of the steering knuckle under the thrust of a steering tie rod. A telescopic strut provided with a shock absorber and a coil spring is superiorly connected to the vehicle body and inferiorly to the steering knuckle.

[0006] Known transmission assemblies realise a fixed steering ratio, understood as the relationship between the degrees imparted by the driver to the steering wheel and those actually obtained at the wheels.

[0007] An object of the present invention is to provide a McPherson -type suspension assembly which allows the steering ratio to be widely varied, by means of a second reduction gear mechanism consisting of a first-class lever, and to accurately adjust said value by means of an electromechanical mechanism regulated on the basis of a control signal.

[0008] SUMMARY OF THE INVENTION

[0009] The technical problem highlighted above is solved by the present invention which relates to a McPherson-type suspension assembly comprising: a steering knuckle configured to carry a wheel hub; a lower arm provided with a first end connected to the steering knuckle and at least a second end configured to be connected to the body of a vehicle with the possibility of rotation; an actuating arm provided with a first end portion connected to the end of the steering box tie rod by means of a first joint with the possibility of rotation about a first axis H; the actuating arm has a second end portion hinged to the steering knuckle by means of a second joint with the possibility of rotation about a second axis; an upper arm provided with a first end hinged to the body and a second end connected to an intermediate portion of the actuating arm by means of a third joint configured to effect the rotation of the actuating arm about a third axis L of rotation; a telescopic strut provided with a shock absorber and a coil spring superiorly connected to the vehicle body and inferiorly to the steering knuckle, characterised by comprising an actuator device configured to move, following an adjustment command, the third joint with respect to the actuating arm and to vary the distance H-L between the first axis H and the third axis L and the distance between the second axis K and the third axis L.

[0010] BRIEF DESCRIPTION OF THE DRAWINGS.

[0011] The invention is described with the accompanying drawings which represent a nonlimiting example in which:

[0012] • figure 1 illustrates, in a perspective view, a McPherson-type suspension assembly made in accordance with the present invention; • figure 2 illustrates, in a top view, the McPherson-type suspension assembly of figure 1;

[0013] • figure 3 illustrates, in a perspective view and on an enlarged scale, a detail of the suspension assembly;

[0014] • figure 4 is a section of the detail of figure 3;

[0015] • figure 5 illustrates in a side view and partly in section a detail of the suspension assembly.

[0016] DESCRIPTION OF THE PREFERRED EMBODIMENT

[0017] With reference to the accompanying drawings, the numeral 1 indicates, a front McPherson-type suspension assembly (and therefore usable on the steered wheels of a vehicle) comprising: a steering knuckle 2 (of a known type and therefore not further detailed) configured to carry a wheel hub (not shown) and provided with parts for the mounting of a brake assembly (not shown); a lower arm 4 provided with a first end 4-a connected to the steering knuckle 2 by means of known techniques and provided with opposite second ends 4-b configured to be connected with the possibility of rotation to the body of a vehicle (partially shown in figure 1); a C-shaped actuating arm 6 provided with a first end portion 6-a connected to the end 7-a of a steering box tie rod 7 by means of a first joint with the possibility of rotation about a first axis H; the C-shaped actuating arm 6 has a second end portion 6-c hinged to the steering knuckle by means of a second joint with the possibility of rotation about a second axis K; an upper arm 10 provided with a first end 10-a hinged to the body and a second end 10-b connected to an intermediate portion of the C-shaped actuating arm 6 by means of a third joint configured to effect the rotation of the actuating arm about a third axis L of rotation. a telescopic strut 12 (of a known type and schematically represented) provided with a shock absorber and a coil spring superiorly connected to the vehicle body and inferiorly to the steering knuckle 2.

[0018] In this way, a translation of the steering box tie rod 7 (which in turn moves following the rotation of the steering wheel) along the direction indicated in figure 1 by an arrow produces a rotation of the actuating arm about the third axis L, which will produce a rotation of the second end 6-b of the actuating arm and, consequently, of the wheel carried by the steering knuckle 2.

[0019] The distance between the axes H and L (see figure 2) is less than that between the axes L and K; for this reason the movement of the steering box tie rod produces an angular rotation about the steering axis L greater than that which would be obtained with a traditional rack and pinion system.

[0020] According to the present invention, an adjustment device 15 is provided, configured to move, following an adjustment command, the third joint with respect to the actuating arm 6 and vary the distance H-L between the first axis H and the third axis L and the distance K-L between the second axis K and the third axis L.

[0021] In other words, the idea of the invention is to have an L axis that is not fixed, but movable with respect to the actuating arm 6.

[0022] In more detail (figure 3 and 4) the adjustment device 15 comprises: an electromechanical actuating assembly with control unit 24 indicated in figure 3 and 4) and a geared motor assembly in turn comprising: a worm screw 20 carried by the shaped actuating arm 6 and housed in a first seat 21 formed in the shaped actuating arm 6; a nut screw 23 axially slidable on the worm screw; an actuator 24 configured to effect the rotation of the worm screw 20 following the emission of the adjustment signal in opposite directions of rotation.

[0023] The third joint is carried by the nut screw 23 in such a way that following the rotation of the worm screw 20, the linear displacement of the third joint with respect to the shaped actuating arm 6 is effected. The translation effected by the worm screw is generally small (the order of magnitude of the translation is + / -10 mm for example). Such translation, however, makes it possible to modify the ratio between the distances K-L and H-L, ratio = (K-L) / ( H-L), by modifying said ratio by means of the control signal.

[0024] A potential adaptation criterion could be the following: the ratio = (K-L) / (H-L) is higher during parking manoeuvres to increase the steering amplification effect; and the ratio = (K-L) / (H-L) is lower in normal driving conditions.

[0025] In this way, the steering ratio, understood as the relationship between the degrees imparted by the driver to the steering wheel and those actually obtained at the wheels, is variable as this depends on the ratio = (K-L) / ( H-L).

[0026] A first end portion of the worm screw 20 is carried by a support 24 disposed at one end of the first seat 21, which has at an opposite end a through opening 25 engaged by the worm screw 20; a second end portion of the worm screw 20 is provided with a first gear wheel 26 housed in a second seat 27 formed in the shaped actuating arm 6 in a position adjacent to the first seat 21; a rotating output shaft 30 of the actuator 24 is provided with a second gear wheel 28 housed in the second seat 27 and engaged with the first gear wheel 26.

[0027] The first gear wheel 26 and the second gear wheel 27 are bevel gear wheels and the shaft of the actuator 24 rotates about an axis which is perpendicular to the axis of the worm screw 20. The actuator 24 comprises a housing fixed to the shaped actuating arm 6 and extending outwards. The second end 10-b of the upper arm 10 is C-shaped (figure 5) and comprises a pair of walls 32 parallel to each other which abut opposite parts of the third joint, ensuring the stable positioning of the joint with respect to the second end 10-b.

Claims

CLAIMS1. A McPherson-type suspension assembly comprising: a steering knuckle (2) configured to carry a wheel hub; a lower arm (4) provided with a first end (4-a) connected to the steering knuckle (2) and at least a second end (4-b) configured to be connected with the possibility of rotation to the body of a vehicle; an actuating arm (6) provided with a first end portion (6-a) connected to the end (7-a) of a steering box tie rod (7) by means of a first joint with the possibility of rotation about a first axis H; the actuating arm (6) has a second end portion (6-b) hinged to the steering knuckle by means of a second joint with the possibility of rotation about a second axis (K); an upper arm (10) provided with a first end (10-a) hinged to the body and a second end (10-b) connected to an intermediate portion of the actuating arm (6) by means of a third joint configured to effect the rotation of the actuating arm about a third axis L of rotation; a telescopic strut (12) provided with a shock absorber and a coil spring superiorly connected to the vehicle body and inferiorly to the steering knuckle (2), characterised by comprising an adjustment device (15) configured to move, following an adjustment command, the third joint with respect to the actuating arm and to vary the distance H-L between the first axis H and the third axis L and the distance between the second axis K and the third axis L.2.- The McPherson-type suspension assembly wherein the adjustment device (15) comprises: an electromechanical actuating assembly with control unit (24) and a geared motor assembly in turn comprising: a worm screw (20) carried by the shaped actuating arm (6) and housed in a first seat (21) formed in the shaped actuating arm (6); a nut screw (23) axially slidable on the worm screw (20); an actuator (24) configured to effect the rotation of the worm screw (20) following the emission of the adjustment signal in opposite directions of rotation; the third joint is carried by the nut screw (23) in such a way that following the rotation of the worm screw (20), the linear displacement of the third joint with respect to the shaped actuating arm (6) is effected.3.- The McPherson-type suspension assembly according to claim 2, wherein a first end portion of the worm screw (20) is carried by a support (24) disposed at one end of the first seat (21), which has at an opposite end a through opening (25) engaged by the worm screw (20); a second end portion of the worm screw (20) is provided with a first gear wheel (26) housed in a second seat (27) formed in the shaped actuating arm (6) in a position adjacent to the first seat (21); a rotating output shaft (30) of the actuator (24) is provided with a second gear wheel (28) housed in the second seat (27) and engaged with the first gear wheel (26).4.- The McPherson-type suspension assembly according to claim 3, wherein the first gear wheel (26) and the second gear wheel (27) are bevel gear wheels and the shaft of the actuator (24) rotates about an axis which is perpendicular to the axis of the worm screw (20).5.- The McPherson-type suspension assembly according to claim 3 or 4 wherein said actuator (24) comprises a housing fixed to the shaped actuating arm (6) and extending outwards.6.- The McPherson-type suspension assembly according to claim 3 or 4 wherein the second end (10-b) of the upper arm (10) is C-shaped and comprises a pair of walls (32) parallel to each other which abut opposite parts of the third joint, ensuring the stable positioning of the joint with respect to the second end (10-b).

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