WO1990015727A1

WO1990015727A1 - Springing system for a vehicle

Info

Publication number: WO1990015727A1
Application number: PCT/FI1990/000164
Authority: WO
Inventors: Ensio Riekko
Original assignee: Ensio Riekko
Priority date: 1989-06-20
Filing date: 1990-06-19
Publication date: 1990-12-27
Also published as: FI893032A; AU5827490A; FI893032A0

Abstract

The invention relates to a springing system for a vehicle, which system is adaptable to unevenness of the ground and comprises springs supporting the vehicle and a system resisting the rolling of the vehicle, the rolling rigidity of the vehicle brought about by said system being designable to be as high as desired irrespective of the sensitivity of the springs supporting the vehicle. To achieve the desired rolling rigidity, sensitivity of the springs and adaptation to the ground, the system (1-3) resisting rolling comprises an element resisting rolling by the torsional rigidity thereof, an antiroll bar (1), which is allowed to roll round the longitudinal axis of the vehicle. The antiroll bar is connected from the foremost connection points (2) to affect the front wheels of the vehicle, and from the rearmost connection points to affect the rear wheels in such a manner that the rolling of the antiroll bar (1) round the longitudinal axis of the vehicle causes the front and rear axis to roll in opposite directions.

Description

1 Springing system for a vehicle

The invention relates to a springing system for a vehicle, said springing system being adaptable to unevenness of the ground and comprising springs sup¬ porting the vehicle and, in addition thereto, a system connecting the springing movements of at least two front wheels and at least two rear wheels and resisting the rolling of both the front and rear axles and at the same time of the entire vehicle, the rolling rigidity of the vehicle brought about by said system being designable to be as high as desired irrespective of the sensitivity of the springs sup¬ porting the vehicle. In order to achieve good ridability and driving comfort, sensitive springs supporting the vehicle and, in addition thereto, antiroll bars are generally used. However, the conventional connection of anti¬ roll bars leads to the fact that the greater the rolling rigidity used in the front and rear axles is, the more poorly the vehicle adapts itself to uneven¬ ness of the ground, and the weight of the vehicle remains easily on two crosswise wheels, whereby the tractive power of the vehicle is considerably reduced, especially when differential gears are used.

Solutions which reduce the drawbacks stated above are previously known in the field. For example,

DE publications 595,936, 901,630, 969,695 and

1,043,101, and US publication 2,859,976 relate to the connection of springs supporting a vehicle to each other, and in these solutions either the rolling rigidity remains too low or the rigidity of the springs supporting the vehicle becomes too great.

US publication 2,840,387, DE publication 2,252,017 and SE publication 181,900 disclose stabil- izers acting crosswise and increasing the rolling rigidity and at the same time the pitching rigidity, and the latter discloses even an alternative wherein the front and rear wheels of the same side are inter- connected by a torsion bar which resists pitching. This tends to make the adaptability to unevenness of the ground more difficult. On the other hand, in systems provided with crosswise stabilizers, the pitching rigidity of the vehicle increases too much if the rolling rigidity is made sufficiently high.

US publication 3,273,912 discloses stiff axles connected by longitudinal pipes to a third pipe, to a central part, so that the axles can roll freely in opposite directions. The central part transmits the rolling-resisting forces from both the front and rear axles to the chassis of the vehicle through springs supporting the vehicle, whereby either the springs become too stiff or the rolling rigidity remains too low. FI publication 73,175 discloses a solution realized in a clearly different manner from this invention, said solution requiring a great deal of room in the chassis of the vehicle.

The invention offers a simple connection of an antiroll bar suitable for common wheel-supporting systems, by means of which connection the rolling rigidity of both the front and rear axles, or each axle of a vehicle with more than two axles, can be made as high as desired, irrespective of the sensitivity of the springs supporting the vehicle, and, in addition, all axles adapt themselves very freely to unevenness of the ground, and the tractive power of the axles remains good even when differen¬ tial gears are used. This connection of the antiroll bar reduces decisively the torsional stresses in the body of a vehicle in uneven terrain and also in cornering. When a wheel on one side of the vehicle runs over a bump or a hole in the road, the connection of the antiroll bar according to this invention causes the load on all the wheels on the same side to grow simultaneous¬ ly and the load on the wheels on the other side to decrease simultaneously. This results in stable behaviour even in a bumpy curve and less stresses than usual in the body of the vehicle.

To achieve what is stated above, the invention is mainly characterized in that the system for resisting rolling comprises an element, an antiroll bar, which resists rolling by the torsional rigidity thereof and which is able to roll round the lon¬ gitudinal axis of the vehicle and connected from two connection points thereof to affect the front wheels of the vehicle, from one connection point to the left and from the other connection point to the right front wheel, and from two other connection points to the rear wheels of the vehicle, from one connection point to the left and from the other connection point to the right rear wheel in such a manner that the rolling of the antiroll bar round the longitudinal axis of the vehicle causes the front and rear axles to roll in opposite directions, one to the left and the other to the right. Due to the fact that the system for resisting rolling interconnects the front wheels and the rear wheels of the vehicle to the chassis of the vehicle so that the rolling-resisting forces exerted by said system are not transmitted from the wheels of the vehicle to the chassis of the vehicle through springs supporting the vehicle, the rolling rigidity can be made as high as desired and the springs supporting the vehicle as sensitive as desired.

The springs supporting the vehicle can be con¬ nected to affect the wheels of the vehicle also through elements belonging to the antiroll bar system, whereby the springs supporting the vehicle eliminate the clearances of the antiroll bar system.

The element resisting rolling by the torsional rigidity thereof, the antiroll bar, can also be, as is previously known, a combination of many parts, e.g. a stiff axle with supporting means, and this element resisting rolling can comprise articulations that freely allow bending but not torsion.

When this element resisting rolling by the torsional rigidity thereof, the antiroll bar, is secured to the chassis of the vehicle in such a manner that said antiroll bar can roll round the longitudinal axis of the vehicle, the connection to one axle, preferably the rear axle, can be arranged in a very simple manner, for example, so that said axle rolls together with the rear end of said anti¬ roll bar.

The antiroll bar system according to this invention resists the rolling of the front and rear axles in the same direction but not the simultaneous rolling of the front and rear axles in opposite directions with respect to the vehicle or the simul¬ taneous, parallel springing movement of the right and left wheels of one axle, e.g. the front axle. Hence it follows that this antiroll bar system cannot alone resist the pitching of the vehicle, for example, when braking; nor can this system for resisting rolling alone support the vehicle, but springs supporting the vehicle are needed for this purpose. In the following the invention will be describ¬ ed in greater detail with reference to the attached drawing, wherein

Figure 1 shows an embodiment of the invention, wherein the element resisting rolling by the torsion¬ al rigidity thereof is a conventional antiroll bar positioned in connection with the rear axle, the two foremost connection points of said antiroll bar being connected through torsion bars to affect even the front wheels.

Figure 2 shows a second embodiment, wherein the element resisting rolling by the torsional rigidity thereof, the antiroll bar, is a bar parallel with the longitudinal axis of the vehicle together with a stiff rear axle fastened to the rear end of said bar. The two connection points of the front end of the longitudinal bar are connected to affect the front wheels through extensions of bottom arms.

Figure 3 is a third embodiment, wherein the longitudinal antiroll bar is connected from two points at both ends thereof to the extensions of sup¬ porting arms, said extensions extending at one end of the vehicle beyond the central line of the vehicle.

Figure 4 shows solutions, seen from behind, wherein the springs are connected to affect both wheels on the same axle in such a manner that when the wheel on one side is lifted, the spring tends to press the other wheel on the same axle downwards.

Figure 1 shows an embodiment of this invention. The springing system comprises springs 4 and 5 sup¬ porting the vehicle and a system 1, 2 and 3 for resisting rolling. The element resisting rolling by the torsional rigidity thereof, an antiroll bar 1, which belongs to said system, is connected in a quite conventional manner from its rearmost points of attachment to the rear axle, but the two points of attachment 2 at the front end of the antiroll bar, which are usually secured to the chassis of a vehicle, are according to this invention connected by means of torsion bars 3 to affect the front wheels in such a manner that the front wheels can freely move simultaneously up and down; the front end of the antiroll bar merely moves simultaneously down and up. Likewise the rear wheels can freely move simul- taneously up and down without being prevented by said antiroll bar; the rear end of the antiroll bar merely moves with the rear axle up and down.

As the vehicle rolls, when both the front and rear axles roll in the same direction with respect to the vehicle, the front and rear axles try to roll the antiroll bar in opposite directions, one at the front end and the other at the rear end. The antiroll bar resists then the rolling of the vehicle by the torsional rigidity thereof. The ratios of the levers in the connections determine in what ratio the front and rear axles resist rolling.

When the front and rear axles roll simultan¬ eously in opposite directions, each axle rolls the antiroll bar 1, one at the front end and the other at the rear end, both in the same direction, and when the antiroll bar is allowed to roll freely round the longitudinal axis of the vehicle, the wheels of the vehicle can adapt themselves very sensitively to unevenness of the ground even if the antiroll bar 1 and the torsion bars 3 had very high torsional rigid¬ ity.

In this manner the rolling rigidity of the vehicle can be designed to be as high as desired even if the springs 4 and 5 supporting the vehicle were very sensitive.

The embodiment of Figure 1 can also be used in a vehicle with independent suspension even in the back. Thereby the antiroll bar 1 should be positioned the other way round so that the ends of the stabil¬ izer bar affect the supporting means of the wheels.

The torsion bars 3 appearing in Figure 1 can also be positioned crosswise, as long as it is taken into account in the connecting direction that the rolling of the antiroll bar round the longitudinal axis of the vehicle causes the front and rear axles to roll in opposite directions, one to the right and the other to the left. Figure 2 shows an embodiment which functions as the embodiment of Figure 1. However, in this embodi¬ ment the element resisting rolling by the torsional rigidity thereof, the antiroll bar, is a stiff rear axle 7 together with a bar 6 parallel with the longi- tudinal axis of the vehicle. The two connection points of the front end of this bar are fastened to the extensions 8 of the bottom arms.

Said bar 6 can function at the same time even as a means for supporting the axle, and it can also comprise articulations which freely allow bending but not torsion.

Figure 3 shows an embodiment wherein the element resisting rolling by the torsional rigidity thereof, the antiroll bar, is a torsion bar 9 parallel with the longitudinal axis of the vehicle, the two connection points at each end of said bar being connected to affect the wheels of the vehicle through extensions 10 and 11 of the supporting arms. At one end of the vehicle, the extensions 11 of the supporting arms are so long that they extend beyond the central line of the vehicle, the right-hand con¬ nection point of the antiroll bar being thereby con¬ nected to affect the left-hand wheel, and the left- hand end of the stabilizer bar being connected to affect the right-hand wheel. Even this embodiment does not resist the rolling of the axles of the vehicle simultaneously in opposite directions, but it does resist the rolling of the axles in the same direction with respect to the vehicle. By selecting suitable ratios of levers, it is possible by means of this embodiment to achieve a relatively high rolling rigidity with a quite thin and light stabilizer bar.

Figures 4 a to c show three previously known manners, seen from behind, to connect the springs supporting the vehicle so that when one wheel is lifted, the spring or the springs tend to press the other wheel on the same axle downwards.

In the topmost axle 4a, the coil springs 12 used in connection with the stiff axle are positioned closer to each other than normal.

In the middle axle 4b, the gas springs 14 are interconnected by a pipe 15 with a valve 16 which cuts off this connection, if necessary. In the lowermost axle 4c, a transverse leaf spring 13 is fastened at the centre thereof to the chassis by means of an articulation.

When a connection of springs which is similar to the one stated above and which affects both of the wheels on the same axle and resists rolling is used on one or more axles in connection with the mounting of the antiroll bar, the ability of the vehicle to adapt itself to unevenness of the ground is improved even to the extent that the front and rear axles can simultaneously roll completely freely in opposite directions.

If the pipe 15 interconnecting the right-hand and left-hand springs 14 of the same axle is closed by a valve 16, another alternative rolling rigidity is achieved for said axle and better stability is achieved for the vehicle, for example, for powerful braking or speeding in a curve. The pipe inter¬ connecting the springs can be closed by the driver, or the valve can be made to close automatically, for example, due to the influence of powerful braking.

Better stability for powerful braking or speed¬ ing in a curve can also be achieved in such a manner that the system according to the invention for resisting rolling is provided with a device by means of which the rolling capability of the antiroll bar belonging to this system round the longitudinal axis of the vehicle can be restricted. The device restricting the rolling of the antiroll bar can be switched on by the driver of the vehicle, or the device can be made to function automatically, for example, due to the influence of powerful braking or speeding.

If the system according to this invention for resisting rolling is provided with a power unit by which the antiroll bar belonging to this invention can be rolled round the longitudinal axis of the vehicle, it is possible to influence the distribu¬ tion of the wheel loads, if desired. Thereby the travelling capability of the vehicle under the most difficult conditions can be improved and, in addi¬ tion, by this arrangement it is possible to effect desired changes to the over- or understeering of a vehicle in cornering. In the specification and the claims, the roll¬ ing of an axle, for example, to the left denotes that the right wheel of the same axle rises higher than the left wheel irrespective of the wheel supporting system and of whether this left and right wheel have a common axle.

The embodiments described above are in no way intended to restrict the invention, but the invention can be modified completely freely within the scope of the claims. It is thus clear that the different details of the system according to the invention do not necessarily have to be those illustrated in the figures, but other solutions are also possible. The system according to the invention is not restricted solely to a car, but the term vehicle refers, in addition to a car, even to a working machine, trailer, etc.

Claims

Claims :

1. A springing system for a vehicle, said springing system being adaptable to unevenness of the ground and comprising springs supporting the vehicle and, in addition thereto, a system connecting the springing movements of at least two front wheels and at least two rear wheels and resisting the rolling of both the front and rear axles and at the same time of the entire vehicle, the rolling rigidity of the vehicle brought about by said system being designable to be as high as desired irrespective of the sens¬ itivity of the springs supporting the vehicle, c h a r a c t e r i z e d in that the system for resisting rolling (1-3, 6-8, 9-11) comprises an element, an antiroll bar (1; 6,7; 9), which resists rolling by the torsional rigidity thereof and which is able to roll round the longitudinal axis of the vehicle and connected from two connection points (2) thereof to affect the front wheels of the vehicle, from one connection point to the left and from the other connection point to the right front wheel, and from two other connection points to the rear wheels of the vehicle, from one connection point to the left and from the other connection point to the right rear wheel in such a manner that the rolling of the anti¬ roll bar (1; 6,7; 9) round the longitudinal axis of the vehicle causes the front and rear axles to roll in opposite directions, one to the left and the other to the right.

2. A springing system according to claim 1, c h a r a c t e r i z e d in that the element resisting rolling by the torsional rigidity thereof is an antiroll bar (1) positioned near the front or rear axle of the vehicle, preferably bent from a bar or pipe, said antiroll bar being connected from the two connection points thereof to affect the axle near said antiroll bar, and that the other two connection points (2) of the antiroll bar (1) are connected to affect the axle at the other end of the vehicle preferably by means of torsion bars (3) .

3. A springing system according to claim 1, c h a r a c t e r i z e d in that the element resisting rolling by the torsional rigidity thereof is a transverse bar, preferably a stiff rear axle (7) together with a longitudinal bar or pipe (6) fastened to said transverse bar, and that the two connection points of one end, preferably the front end, of said longitudinal bar or pipe (6) are connected to affect the wheels of the vehicle by means of levers, prefer¬ ably reaction rods or extensions (8) of supporting arms.

4. A springing system according to claim 1, c h a r a c t e r i z e d in that the element resisting rolling by the torsional rigidity thereof is a longitudinal bar or pipe (9), the two connection points of each end of said bar or pipe being con¬ nected to affect the wheels of the vehicle through levers, preferably reaction rods or extensions (10,11) of supporting arms, and that at one end of the vehicle these lever arms (11) are arranged to extend beyond each other, whereby the right-hand con¬ nection point of the stabilizer bar (9) is connected to affect the left-hand wheel and the left-hand con- nection point is connected to affect the right-hand wheel.

5. A springing system according to claims 1, 2, 3 or 4, c h a r a c t e r i z e d in that the system further comprises at least on one axle a spring (13) or springs (12 and 14) supporting the vehicle and connected in a previously known manner so that when a wheel on one side of said axle is lifted, said spring or springs tend to press the other wheel on the same axle downwards. 6. A springing system according to claim 5, c h a r a c t e r i z e d in that the connection (15) joining the springs (14) of the left and right wheel on the same axle can be switched off either by the driver or automatically, if desired. 7. A springing system according to claims 1 to

6, c h a r a c t e r i z e d in that the system comprises a device by means of which the rolling capability of the antiroll bar (1; 6,

7; 9) with respect to the vehicle can be restricted either by the driver or automatically, if desired.

8. A springing system according to claims 1 to

7, c h a r a c t e r i z e d in that the system comprises a power unit by means of which the antiroll bar (1; 6,7; 9) can be rolled round the longitudinal axis of the vehicle.