WO2014068392A2

WO2014068392A2 - The push-rod suspension for a motor vehicle

Info

Publication number: WO2014068392A2
Application number: PCT/IB2013/002448
Authority: WO
Inventors: Gaetano SCAPINELLI; Daniele MANFREDINI
Original assignee: Scapinelli Gaetano; Manfredini Daniele
Priority date: 2012-11-05
Filing date: 2013-11-05
Publication date: 2014-05-08
Also published as: WO2014068392A3; ITMO20120271A1

Abstract

The push-rod suspension (1) for a motor vehicle, associable with a pair of wheels (2, 3) of the front axle or rear axle of the vehicle, comprises: two push- rods (6, 7), each connectable at one of their ends to a hub bracket of a respective wheel (2, 3); a first and a second lever means (8, 9), each rotatably coupled to a respective push-rod (6, 7), and suitable for oscillating around a relative rotation axis (X, Y), arranged substantially crossways to the push-rods (6, 7), upon a thrust by the respective push-rod; first elastic biasing means connected to the lever means (8, 9) and suitable for counter acting the respective oscillation around the relative axis (X, Y); and anti-rolling means (10) connected to the first and second lever means (8, 9), which are of the hydraulic type and are configured in such a way that, upon a rotation of any one of the lever means (8, 9), around the respective axis (X, Y) due to a thrust of the respective push-rod (6, 7), the anti-rolling means (10) force the remaining lever means (8, 9) to perform a rotation around the respective axis (X, Y), to produce a movement of the relative push-rod (6, 7), so that this can push on the hub bracket.

Description

PUSH-ROD SUSPENSION FOR MOTOR VEHICLES

Technical Field

The present invention relates to a push-rod suspension for motor vehicles, particularly for competition single-seaters.

Background Art

Push-rod suspensions are known which include, for each wheel, a double-fork support, substantially made up of two superimposed triangular elements, which supports the wheel hub bracket, to which an end of the push-rod is connected. The other end of each push-rod is rotationally coupled to a respective equalizer (or similar mechanical means), often arranged inside the chassis of the motor vehicle and hinged so as to be able to rotate around a fixed axis with respect to the chassis itself.

Each equalizer is connected to elastic means, such as torsion bars, shock- absorbers, and other like devices known to expert persons in the field.

It is known that during steering, the suspension is stressed of the outer wheels with respect to the curve, while the chassis is subject to rolling following which the load applied on the inner wheels is reduced.

Because of this, the tyres of the inner wheels are subject to skidding, i.e., sliding on the road surface, which causes faster wear of the relative tread.

In this situation, furthermore, the tyres of the inner wheels lose grip, and this can lead to negative consequences in terms of safety, both for the driver of the motor vehicle and for anyone in the vicinity.

To try and overcome this problem, so-called "anti-rolling" bars are currently used, i!e., C-shaped flexible bars, the ends of which are connected to the two equalizers, so the rotation of the equalizer connected to the inner wheel produces a torsion of the bar, following which the bar itself causes a rotation of the equalizer of the outer wheel, which tends to push it downwards, in an attempt to offset the aforementioned load loss.

This solution has proven extremely unsatisfactory, above all when steering is performed at high speed, in which case, as is known, the motor vehicle is subject to more accentuated rolling.

Disclosure of the Invention The main aim of the present invention is to provide a push-rod suspension for a motor vehicle which allows overcoming the aforementioned problem of load loss on the outer wheels due to the rolling to which the motor vehicle is subject during steering.

Within this aim, one object of the present invention is to provide a push-rod suspension able to also offset the most significant load losses occurring on the outer wheels when the steering is performed at high speeds.

Another object of the present invention is to provide a push-rod suspension which permits overcoming the aforementioned drawbacks of the state of the art within the scope of a simple and rational solution that is easy and effective to use and which is inexpensive.

The above mentioned objects are achieved by the present push-rod suspension for a motor vehicle according to claim 1.

Brief Description of the Drawings

Other characteristics and advantages of the present invention will appear more evident from the description of a preferred, but not sole embodiment, of a push- rod suspension for motor vehicles, illustrated in an exemplary but not restrictive way on the attached drawing tables wherein:

the figure 1 is a schematic front view of the front axle of a competition single- seater on which is fitted a push-rod suspension according to the invention;

the figure 2 is a top schematic view of the anti-rolling means of the push-rod suspension according to the invention.

Ways of carrying out the Invention

With particular reference to such illustrations, globally indicated by 1 is a push- rod suspension 1 for a motor vehicle, associable with a pair of wheels 2, 3 of the front axle or of the rear axle.

The motor vehicle can be of any type, in particular a competition single-seater, wherein the front axle is schematically shown in figure 1, from a front viewpoint.

In detail, especially in the case of the motor vehicle being a single-seater, the suspension 1 comprises, for each wheel 1 with which it is associated, a pair of supporting forks 4, each of triangular shape, having a respective end vertex hingeable to a respective hub bracket (not shown for simplicity, but widely known to expert persons in the field), and also having opposite ends hingeable to a chassis 5 of said motor vehicle.

As can be seen in the figure 1, the proposed suspension 1 comprises, in its more general aspects: two push-rods 6, 7 each connectable to one of its ends to the hub bracket of the respective wheel 2, 3; and a first and a second leyer means 8, 9, each rotatably coupled to a respective push-rod 6, 7, and suitable for oscillating around a relative rotation axis X, Y, arranged substantially crossways to the push-rods 6, 7, upon a thrust by the respective push-rod 6, 7 itself.

Such X, Y axes can be fixed with respect to the chassis 5 of the motor vehicle, and in any case do not depend on the movements of the elements making up the invention.

Furthermore, the suspension 1 of the invention comprises: first elastic biasing means (not shown and explained in detail later on), connected to the lever means 8, 9, and suitable for counter acting the respective oscillation around said relative axis X, Y.

Preferably, the first and the second lever means comprise a first and a second equalizer 8, 9 respectively, or similar means such as square levers, etc....

Always preferably, the first elastic biasing means comprise at least a first and a second torsion bar (not shown for illustration readability reasons), connected to the first and the second lever means 8,9 respectively (i.e., to the right and the left equalizer), and can also comprise, in addition or alternatively, two shock absorbers 80, 90 connected rotatably atto one of its ends, to the respective lever means 8, 9 and fixed at the opposite end. -

The invention also comprises particular and advantageous anti-rolling means 10 (in figure 1 only schematically indicated for reasons of clear representation) connected to the lever means 8, 9, which are of the hydraulic type and are shown in such a way that, upon a rotation in a first direction of any one of the lever means 8, 9, around the respective axis X, Y, due to the thrust of the respective push-rod 6, 7, the anti-rolling means 10 force the remaining lever means 8, 9 to perform a rotation in a direction in agreement with such first direction (clearly around the respective axis X, Y), to produce a shift of the respective push-rod 6, 7 which pushes on the relative hub bracket.

Before explaining preferential construction aspects of the invention, to be detailed later on with the aid of the figure 2, its general operation is now described.

When the motor vehicle steers at a not low speed, e.g., to the left, it begins to roll, i.e., a rotation with respect to its longitudinal axis, which causes it to sway on its right side, and this results in the right wheels 2, i.e., the outer wheels with respect to the bend taken, undergoing a load increase to which they are subject, while the left, or inner wheels 3, lose load (to the extent, in certain cases, of lifting off the road surface).

In this situation, the right push-rod 6 is pushed by the respective wheel 2 towards the inside of the motor vehicle and produces a rotation of the right lever means 8, around its axis X, in a clockwise direction in the view of figure 1 (i.e., towards the inside of the motor vehicle), which stresses the anti-rolling means 10 in such a way that these, in turn, force the left lever means 9 to perform a rotation of its own (clockwise, i.e., towards the outside) with respect to the axis Y (the entity of which will be spoken of in a following paragraph), so that such lever means 9 acts on the left push-rod 7 so as to increase the load on the left wheel 3, in practice pressing it downwards, and thus offsetting the above bend roll.

Obviously, what has been said also holds true in the case of steering to the right. To best understand the advantages of the hydraulic anti-rolling means of the invention, one of its preferred embodiments will now be described, schematically shown in figure 2.

The anti-rolling means 10 comprise two pairs of hydraulic cylinders 1 1, 15, 19, 23.

The first pair of hydraulic cylinders first of all includes a first cylinder IT having a hollow body 12 wherein a piston 13 is arranged sliding and this piston 13 comprises a rod 14 connected to the first lever means 8, i.e., to the right lever means.

The first pair also comprises a second cylinder 15 having its own hollow body 16, communicating in a fluid-dynamic way with the hollow body 12 of the first cylinder 11, wherein is arranged sliding a respective piston 17 having a rod 18 connected to the second lever means 9.

When, in the present description, we say that the hollow bodies of the hydraulic cylinders are communicating, what is obviously meant is that the respective cavities are communicating, defined laterally by the respective liners, wherein slide the heads of the pistons, in which cavity the work fluid is located.

In the preferred embodiment shown in the figure 2, the hydraulic cylinders 11 , 15, 19, 23 of each pair are integrated the one with the other, so that the respective internal work fluid accommodation volumes together define a single internal chamber, having a same liner, wherein both pistons slide.

The anti-rolling means 10 also comprises a second pair of hydraulic cylinders comprising a third cylinder 19 having its own hollow body 20 wherein is arranged sliding the piston 21, which has a rod 22 connected to the second lever means 9.

Such second pair therefore comprises a fourth cylinder 23 having a hollow body 24 of its own, communicating in a fluid dynamic way with the hollow body 20 of the third cylinder 19, wherein is arranged sliding a respective piston 25 having the rod 26 connected to the first lever means 8.

For the purpose of its connection with the anti-rolling means, each lever means 8, 9 can form a fork 34, 35 made up of two parallel elements, each of which is connected to a different end of a respective pair of hydraulic cylinders 1 1, 15, 19, 23, if necessary with the interposition of elastic means illustrated in detail below.

Advantageously, the sizing of the hydraulic cylinders described above can be explained as follows.

As shown in figure 2, the hollow body 12 of the first cylinder 1 1 has an internal work fluid accommodation volume which has a cross section S 1 bigger than the cross section S2 of the internal volume of the hollow body 16 of the second cylinder 15.

In the same way, the third cylinder 19 has a cross section S3 of the internal volume of the respective hollow body 20 which is bigger than the cross section S4 of the internal volume of the hollow body 24 of the fourth hydraulic cylinder 23.

Consequently, as shown by indicating the rods of the hydraulic cylinders 1 1, 15, 19, 23 both in continuous and dotted line, when for example the first cylinder 11 is pushed by the right lever means 8 (during steering to the left), its rod 13 performs a given stroke inside the hollow body 12 and moves a given volume of work fluid.

Because the hollow body 12 of the first cylinder 11 communicates with that of the second cylinder 15, which however has an internal section S2 smaller than that of the other, the work fluid forces the piston 27 of the second cylinder 17 to perform a movement greater than the stroke performed by the piston 13 of the first cylinder 11.

Consequently, considering the rod 18 of the second cylinder 15 is connected to the left lever means 9, then the left push-rod 7 undergoes a greater thrust than that undergone by the push-rod 6 due to the load increase on the right wheel 2 during steering, so that the left wheel 3 undergoes a load increase which fully offsets the loss undergone due to rolling, including in the case of bends taken at the highest speeds.

Consequently, the invention perfectly surpasses all the limits of the state of the art, making available a hydraulic anti-rolling means 10 able to ensure the perfect grip (and rolling) of the outer wheel of the motor vehicle mounting the proposed suspension.

It is clear that what has been said for the first and the second cylinders 11, 15 also applies mutatis mutandis to the third and fourth cylinders 19, 23.

The sizing of the hydraulic cylinders comprised in the invention is suitably adjustable to establish the multiplication factor which the anti-rolling means 10 must provide in transmitting the stress of the outer wheel to the inner wheel to offset the steering roll, and the pairs of cylinders 11, 15, 19, 23 can be identical the one to the other or different, and in any case are adjustable according to the requirements of the single application.

Preferably, in order to convey a certain flexibility to the connection between the - anti-rolling means 10 and the lever means 8, 9, second elastic means 27, 28 are provided placed between both the rod 18 of the piston 17 of the second cylinder 15 and the second lever means 9, and between the rod 26 of the piston 25 of the fourth cylinder 23 and the first lever means 8.

Such elastic means can comprise a first series of Belleville washers 27 having opposite ends facing relative locator plates 31, 32 (see fig. 2 again), which plates 31, 32 are connected to the rod 18 of the piston 17 of the second cylinder_. 15 and to a connection shaft 29 fastened to the second lever means 9 respectively.

The invention also comprises a second series of Belleville washers 28 having opposite ends facing relative locator plates 33, 34, which are connected to the rod 26 of the piston 25 of the fourth cylinder 23 and to another connection shaft fastened to the first lever means 8 respectively.

Advantageously, thanks to the use of a series of Belleville washers 27, 28, in the above-described configuration, the user can pre-establish the percentage of the stroke of the rods 25, 17 of the second and fourth cylinders 15, 23 which has to be absorbed by the washers themselves.

Consequently, after absorbing the preset aliquot part of the stroke of the rod 17, 25, the involved series of Belleville washers 27, 28, contained between its plates 31, 32, 33, 34, becomes rigid and transmits the remaining part of the stroke to the relative shaft 29, 30, which transfers it to the respective lever means 8, 9, so as to perform the anti-rolling function of the invention.

In particular, the rods 14, 18, 22, 26 of the hydraulic cylinders can be connected (with the interposition or not of the second elastic means 27, 28 and of the shafts 29, 30) to the respective lever elements 8, 9 by means of rotoidal couplings.

More in detail, as shown in figure 2, at each end of the cylinders 11, 15, 19, 23 a uniball joint 36, 37, 38, 39 can be fixed, so as to define two opposite couples of uniball joints.

Furthermore, each joint couple 36, 37, 38, 39 is connected through a pin 40, 41 which crosses the eyelets obtained in the movable elements of the joints.

The two opposing pins 40, 41 are in turn fixed at the respective fork 34, 35, being either trident shaped or fork shaped as shown in the figures, which is connected to its lever means 8, 9 by means of said rotatable coupling.

In this case, the pins 40, 41 cross the prongs of the forks 34, 35, while the joints 36, 37, 38, 39 are housed in respective spaces defined between the prongs.

In this way, an independent activation of the couples of cylinders is allowed, as they are functionally isolated from each other by means of the uniball joints/ forks system.

In fact, upon a sudden steering, one of the cylinder couples 1 1, 15, 19, 23 can produce said sudden load increase compensating for the loss derived from the rolling, without being obstructed by the other couple 11, 15, 19, 23, which remains in the rest configuration.

Moreover, uniball joints/ forks system supports the anti-rolling means 10 of the invention without the need of support casing or the like.

It has in fact been ascertained how the described invention achieves the proposed objects, making available a push-rod suspension having special anti- rolling means of the hydraulic type able to fully overcome the problems caused by the roll of the motor vehicle during steering, both at low and at high speeds.

Claims

1) Push-rod suspension (1) for a motor vehicle, associable with a pair of wheels (2, 3) of the front axle or rear axle of said vehicle, and comprising:

at least two push-rods (6, 7), each correctable at one of their ends to a hub bracket of a respective wheel (2, 3);

at least a first and a second lever means (8, 9), each rotatably coupled to a respective push-rod (6, 7), and suitable for oscillating around a relative rotation axis (X, Y), arranged substantially crossways to said push-rods (6, 7), upon a thrust by said respective push-rod;

first elastic biasing means connected to said first and second lever means (8, 9) and suitable for counter acting the respective oscillation around said relative axis (X, Y); and

anti-rolling means (10) connected to said first and second lever means (8, 9); said suspension (1) being characterized by the fact that said anti-rolling means (10) comprises:

at least a first pair of hydraulic cylinders made up of a first cylinder (1 1) having a hollow body (12) wherein is arranged sliding a piston (13), having a rod (14) connected to said first lever means (8), and of a second cylinder (15) having its own hollow body (16), communicating in a fluid-dynamic way with said hollow body (12) of the first cylinder (11), wherein is arranged sliding a respective piston (17) having a rod (18) connected to said second lever means (9); and at least a second pair of hydraulic cylinders made up of a third cylinder (19) having a hollow body (20) wherein is arranged sliding a piston (21), having a rod (22) connected to said second lever means (9) and of a fourth cylinder (23) having a hollow body (24) of its own, communicating in a fluid dynamic way with said hollow body (20) of the third cylinder (19), wherein is arranged sliding a respective piston (25) having a rod (26) connected to said first lever means (8);

so that, upon a rotation of any one of said first and second lever means (8, 9), around said respective axis (X, Y), due to a thrust of said respective push-rod (6, 7), the anti-rolling means (10) force the remaining lever means (8, 9) to perform a rotation around said respective axis (X, Y), so as to produce a movement of the relative push-rod (6, 7), so that the latter can push on said hub bracket.

2) Suspension (1) according to claim 1, characterized by the fact that said hollow body (12) of said first cylinder (11) has an internal work fluid accommodation volume which has a cross section (SI) bigger than the cross section (S2) of an internal volume of the hollow body (16) of said second cylinder (15); wherein said third cylinder (19) has the cross section (S3) of an internal volume of the respective hollow body (20) which is bigger than the cross section (S4) of an internal volume of said hollow body (24) of the fourth hydraulic cylinder (23).

3) Suspension (1) according to claims 1 or 2, characterized by the fact that it comprises second elastic means (27, 28) placed between both said rod (18) of the piston (17) of the second cylinder (15) and said second lever means (9), both between said rod (26) of the piston (25) of the fourth cylinder (23) and said first lever means (8).

4) Suspension (1) according to claim 3, characterized by the fact that said second elastic means can comprise at least a first series of Belleville washers (27) having opposite ends connected to said rod (18) of the piston of the second cylinder and to said second lever means (9) respectively, and a second series of Belleville washers (28) having opposite ends connected to said rod (26) of the piston of the fourth cylinder and to said first lever means (8), respectively.

5) Suspension (1) according to one or more of the preceding claims, characterized by the fact that said first and second lever means comprise a first and a second equalizer (8, 9), respectively.

6) Suspension (1) according to claim 5, characterized by the fact that said first and second equalizers (8, 9) shape a-respective protruding arm (29, 30), to which are rotatably coupled both said respective push-rods (6, 7) and opposite ends of said anti-rolling means (10).

7) Suspension (1) according to one or more of the preceding claims, characterized by the fact that said first elastic biasing means comprise at least a first and a second torsion bars connected to said first and second lever means (8, 9), respectively. 8) Suspension (1) according to one or more of the preceding claims, characterized by the fact that it comprises, for each wheel (2, 3) with which said suspension is associated, a pair of supporting forks (4), each of triangular shape, having a respective end vertex hingeable to a respective hub bracket and having opposite ends hingeable to a chassis (5) of said motor vehicle.

9) Suspension (1) according to one or more of the preceding claims, characterized by the fact that said first and second lever means (8, 9) are rotatably coupled to a respective shock absorber (80, 90) to contrast the relevant oscillation.