SE540192C2 - Spring Suspension - Google Patents

Abstract

The invention relates to a spring suspension (3) for a wheel axle (4) of a vehicle (1), wherein the spring suspension (3) comprises a spring link (6) which is mounted to a vehicle body (8) on the vehicle (1) via a spring bracket (5) and a shaft bracket (7). The spring link (6) comprises a leaf spring (16) with a loop (17) at one end of it and is mounted to the spring bracket (5) via the loop (17). The loop (17) on the leaf spring (16) is turned downwards in a vertical vehicle direction d. When the vehicle (1) is subjected to lateral forces when cornering and the force on the wheel axle (4) of the vehicle (1) thereby increases in the vertical vehicle direction d, the spring link (6) to be deformed in the vertical vehicle direction as well as in the horizontal vehicle direction so that the distance between the center of the loop (17) and the wheel axle (4) decreases, which causes an understeer effect.

Description

Spring suspension Field of the invention The present invention relates to a spring suspension for a wheel axle in a vehicle according to the preamble of the independent claim.

Background of the invention When a vehicle's wheel moves vertically, for example when cornering or turning, the vehicle can be exposed to turning forces. These forces allow the vehicle to start turning without the driver turning the steering wheel. If the steering effect occurs when one of the wheels lifts while the opposite wheel is depressed, such as when the body tilts or tilts sideways, it is called tilt steering. For example, the inner wheel can lighten during hard cornering.

When tilting, a difference occurs in wheel angles between the two wheels, which lightens and depresses, respectively, which causes the vehicle to be understeered or overridden. Override means that the vehicle turns more than expected in a curve. For example, sports cars are often neutral to oversteered to more easily respond to the driver's commands during more advanced driving.

Understeer means that the vehicle does not turn as much as expected but strives to go straight ahead in a curve. Light understeer is sought after by most vehicle manufacturers, as it gives the vehicle a more predictable and easy-to-handle behavior in a critical situation. Excessive understeer, however, makes the vehicle heavy-handed. In general, front-wheel drive vehicles are more understeered than rear-wheel drive.

There are several different solutions for making a vehicle understeered. For example, GB-2211473-A shows a rear wheel axle suspension for a vehicle.

The suspension uses a rocker effect to reduce the magnitude of forces transmitted to the vehicle body. In this way, an understeer effect can be given, while shock absorption is obtained when a rear wheel strikes a bump.

US-20030098565-A1 discloses a leaf spring suspension for a rear wheel axle. The suspension includes leaf springs that are attached to the vehicle with front and rear supports. The rear supports are rigid in a transverse direction, and the front supports are resilient in a transverse direction. When the vehicle is subjected to transverse lateral forces, a pivot pole is created for the rear axle which is located behind the center of the rear axle. The wheel axle will then tilt slightly with respect to the longitudinal direction of travel of the vehicle and thus create understeer of the vehicle when the vehicle passes through a curve. The solution uses a specially designed bearing layer that provides the opportunity for transverse movement.

In the case of another type of suspension, for example two-bellows suspension, the wheels of the vehicle are suspended to the vehicle body via each a spring link which connects the wheel axle to the body via a spring load each. Under load, the spring bracket and the spring link are pressed downwards in the vertical direction. The load gives rise to an angular change in the spring link and thus an "extension" of the spring link in the horizontal direction. The extension means that the horizontal distance between the spring bracket and the wheel axle increases. the outer wheel is longer in the horizontal direction than the spring link in the wheel suspension on the inner wheel.The wheel axle is then tilted and if the wheel axle is a rear axle then the vehicle can be overridden, which is not desirable.

The object of the invention is thus to provide an improved wheel suspension which gives the vehicle a sub-controlled behavior when using a spring link which connects the wheel axle to the body of the vehicle.

Summary of the invention The object described above is achieved by a spring suspension for a wheel axle of a vehicle, the spring suspension comprising a spring link which is mounted to a vehicle body on the vehicle via a spring bracket and a axle bracket. The spring link comprises a leaf spring with a loop at one end and is mounted to the spring bracket via the loop. The loop on the leaf spring is turned downwards in a vertical vehicle direction, ie. When the vehicle is subjected to lateral forces when cornering and the force on the vehicle's wheel axle thereby increases in the vertical vehicle direction, ie from a ground plane, the spring link will be deformed in the vertical vehicle direction or in the horizontal vehicle direction. in the horizontal vehicle direction compared to when the force on the vehicle's wheel axle does not increase in the vertical vehicle direction dv, which causes a understeer effect.

By turning the leaf spring with the loop downwards, increased understeer of the vehicle can thus be achieved while maintaining the driving height. The driving height is the distance between the underside of the vehicle and the ground level. Desired understeer characteristics can thus be obtained without impairing the driving height. Existing spring bracket and shaft bracket can be used without any major modifications. The solution thus becomes cheap and easy to achieve, at the same time as the driving characteristics are improved.

The spring ridge comprises a single-leaf spring. The spring link then has only one leaf spring, and in this way the weight can be reduced compared to having, for example, a two-leaf spring.

Preferred embodiments are described in the dependent claims and in the detailed description.

Brief description of the attached figures The invention will be described below with reference to the accompanying figures, of which: Fig. 1 shows a vehicle with spring suspensions for the various wheel axles.

Fig. 2 shows a spring suspension according to an embodiment of the invention.

Fig. 3 shows a cross section A-A of the spring suspension in Fig. 2.

Fig. 4A shows an example of a spring link with a centered loop.

Fig. 4B shows an example of a spring link with an overlying loop.

Fig. 4C shows an example of a spring link with an underlying loop.

Fig. 5 shows an example of a spring link with a safety band.

Detailed Description of Preferred Embodiments of the Invention Fig. 1 schematically shows a truck 1 with wheels 2 connected to wheel axles 4. The wheel axles 4 are suspended via spring suspensions 3 to a vehicle body 8 (Fig. 2), for example a vehicle frame. The vehicle frame can consist of two elongate parallel frame side beams which are connected to each other by a number of cross beams.

Fig. 2 shows a spring suspension 3 for a wheel axle 4 for the truck 1 in Fig. 1 in more detail. The spring suspension 3 can be used for vehicles other than trucks, for example passenger cars, emergency vehicles, etc. In Fig. 2 only a spring suspension 3 is shown located near one end of the wheel axle 4, but it is understood that in most cases there is also a second spring suspension 3 at the other end of the same wheel axle 4.

The spring suspension 3 comprises a spring link 6 which extends substantially in a horizontal vehicle direction dhoch which is mounted to a vehicle body 8 on the vehicle 1 via a spring bracket 5 which houses a bearing 13. The spring bracket 5 is attached to the vehicle body 8, more specifically the frame side beam, for example the frame side beam or rivets. The spring link 6 comprises a leaf spring 16 with a loop 17 at one end and is mounted to the spring bracket 5 via a bolt 12 extending in a substantially transverse vehicle direction through the bearing 13 and through the loop 17 on the leaf spring 16. The center of the loop 9 is excellent in the figure. . The spring link 6 is attached at its other end to the wheel axle 4 via a shaft bracket 7. The center 18 of the wheel axle 4 is excellent in the figure. The axle bracket 7 can be, for example, a bridge with brackets 28 which are fastened over projecting pins 31 on the wheel axle 4, and which fasten the spring link 6 to the wheel axle 4 by screwing the brackets 28 with bolts or screws in a plate 32. Other ways of attaching the spring link 6 to the wheel axle 4 are, however, conceivable. The axle bracket 7 is attached to a shock absorber 10 which in turn is attached to the vehicle body 8. In the example in the figure the spring link 6 has an extension 22 which extends behind the wheel axle 4 in the horizontal vehicle direction dh, and which abuts the underside of an air bellows 11 .

As shown in the figure, the loop 17 on the leaf spring 16 is turned downwards in a vertical vehicle direction dv. By "downwards" is meant here in a direction towards the ground plane. In other words, the spring link 6 is mounted so that the loop 17 on the leaf spring 16 is an underlying loop 17. When the vehicle 1 is subjected to lateral forces when cornering and the force on the vehicle's wheel axle 4 thereby increases in the vertical vehicle direction dV, the spring link 6 will be deformed in the vertical vehicle direction, ie in the horizontal vehicle direction, i.e. the distance between the center of the loop 9 and a continuous wheel axle center 18 on the wheel axle 4 decreases in the horizontal vehicle direction, compared with when the force on the vehicle's wheel axle 4 does not increase in the vertical vehicle direction dv. The loop 17 here has a substantially circular shape.

Fig. 3 shows a cross section of the spring bracket 5 in Fig. 2 along the line A-A. The spring bracket 5 is here formed with two stirrups 33 which house the bearing 13 between them. The bolt 12 extends through the bearing 13 along a shaft 15, which here also forms an axis of rotation 15 of the loop 17 (Fig. 2) through the center of the loop 9. The bolt 12 is fastened with a nut 14 and a joint 35. The leaf spring 16 is tight around the bearing 13 and is movable about the shaft 15. Between the stirrups 33 and the bearing 13, washers 34 can be arranged to receive forces in the transverse vehicle direction dt.

The spring link 6 is thus shown here rigidly mounted to the spring bracket 5 in the transverse vehicle direction dt. In this way, no movements of the spring meadow in the transverse vehicle direction dt are permitted. The bearing 13 can be, for example, a rubber bearing or a ball bearing.

Next, the principle of how understeer is achieved with the above-described Spring Suspension 3 will be explained. Figs. 4A and 4B first show two examples of known spring suspensions when oversteer or insufficient understeer is obtained. The accepted way of providing understeer for a rear wheel axle 4 has been to tilt the spring link 6, which inclination is illustrated in Figs. 4A and 4B. However, this design does not provide understeer effect to the desired degree if the driving height (or ground clearance) is not reduced, since the rotation of the loop 17 counteracts the understeer effect, which is described in more detail in connection with Fig. 4B below. By a reduction of the driving height is meant, for example, extending the spring bracket 5 downwards so that an increased inclination of the spring link 6 can be achieved. Fig. 4C then shows the understeer according to the invention. In the figures, the loop 17 is illustrated as a fixed point, while the shaft bracket 7 is moved. In the examples, the shaft bracket 7 is subjected to an upward vertical force F during heeling movement. The spring suspension 3 then sits, for example, on the outer side of the vehicle 1 (Fig. 1) in a curve, and hangs a rear wheel axle 4. It is then desirable that the distance between the center of the loop 9 and the axle bracket 7 is reduced to provide an understeer effect. The wheel axle 4 will then be tilted and understeer can be achieved. In Figures 4A-4C, the spring bracket 5 is not shown, and the shaft bracket 7 is schematically illustrated as a rectangle.

Fig. 4A schematically shows the spring suspension 3 with a spring link 6, where the spring link 6 has a centered loop 17, a so-called “Berlin loop.” A centered loop 17 means that the loop 17 is centered around a center line of the spring link 6.

The spring link 6 is attached to the shaft attachment 7 at an angle? from the horizontal vehicle direction dhned to the center of the loop 9. The loop 17 can rotate around the center 9 of the loop through the bearing 13. The dashed line shows how the spring link 6 is rotated upwards around the center 9 of the loop when the axle bracket 7 is subjected to the force F. a vertical vehicle direction due to the force F. At the same time the loop 17 is rotated around the center point 9 of the loop, which causes the axle bracket 7 to move in the horizontal vehicle direction dhen distance dx. The distance dx can be approximated to Image available on "Original document" and thus depends only on the bend dz and the slope a. This spring suspension 3 does not provide sufficient understeer.

Fig. 4B schematically shows the spring suspension 3 with a spring link 6, where the spring link 6 has an overlying loop 17. The loop 17 is then turned away from the ground plane. The spring link 6 is here attached to the shaft bracket 7 at an angle? from the horizontal vehicle direction dhned to a place on the spring link 6 where the loop 17 is started. The radius of the loop 17 is marked here with "e". The loop 17 can rotate around the center point 9 of the loop through the bearing 13. The dashed line shows how the spring link 6 is rotated upwards around the center point 9 of the loop dz in a vertical vehicle direction due to the force F. At the same time the loop 17 is rotated around the center point 9 of the loop an angle? which causes the axle bracket 7 to move in the horizontal vehicle direction dh away from the center 9 of the loop which acts on the shaft bracket 7 and which pulls on the spring link 6. The distance dx can be approximated to: Image available on "Original document" and thus depends on both the inflection dz and the slope a, as well as the angular change? and the radius of the loop 17 e. In this case, e ·? over? · dz, which means that the distance between the center of the loop 9 and the shoulder bracket 7 increases, which gives understeer which is not desirable.

Fig. 4C schematically shows the spring suspension 3 with a spring link 6, where the spring link 6 has an underlying loop 17. The loop 17 is then facing the ground plane. The spring link 6 is here attached to the shaft bracket 7 at an angle? from the horizontal vehicle direction dhupp to a place on the spring link where the loop 9 begins. The spring link 6 is thus mounted at an angle? upwards in a direction from the shoulder bracket 7 to the spring bracket 5. The radius of the eye 9 is marked here with "e". The loop 17 can rotate around the center 9 of the loop through the bearing 13. The dashed line shows how the spring link 6 is rotated upwards around the center 9 of the loop when the shaft bracket 7 is exposed to the force F. The shaft bracket 7 moves when the distance dz in a vertical vehicle direction the loop 17 around the center 9 of the loop an angle? which causes the axle bracket 7 to move in the horizontal vehicle direction dhmot the loop center 9 a distance dx. This occurs because the loop 9 folds in by the force F acting on the shaft bracket 7. The distance dx can be approximated to: Image available on "Original document" and thus depends on both the bend dz and the slope a, as well as the change in angle? and the radius e of the loop 17. In this case,? · dz dominates over e ·?, which means that the distance between the center of the loop 9 and the shoulder bracket 7 decreases, which gives understeer. The spring link 6 is thus deformed in the vertical vehicle direction, i.e. in the horizontal vehicle direction and the distance between the center of the loop 9 and a continuous wheel axle center 18 on the wheel axle 4 thus decreases in the horizontal vehicle direction compared to when the force on the vehicle axle dv. The underlying loop 17 on the spring link 6 is thus not locked to the spring link, but can be opened or closed depending on how the vehicle turns and on which wheel axle 4 and on which side of the wheel axle 4 as the spring suspension 3 is mounted.

Fig. 5 shows an exposed spring link 6 with a safety strap 19. The safety strap 19 at least partially encloses the spring link 6 to hold the spring link 6 together in case a breakage occurs. The figure shows how the safety belt 19 extends from a mounting area 23 on the leaf spring 16 within which mounting area 23 the leaf spring 16 is adapted to be mounted to the wheel axle 4 (Fig. 2). The safety strap 19 then extends along a first side 25 of the leaf spring 16 to enclose the loop 17, and further along a second side 26 of the leaf spring 16 to the mounting area 23 of the leaf spring 16. The first and second sides 25, 26 are opposite sides of the leaf spring 16. The first and the second sides 25, 26 also form the outer sides of the leaf spring 16 in a vertical vehicle direction dv (Fig. 2).

The mounting area 23 comprises, for example, two opposite flat surfaces of the leaf spring 16, on which the safety band 19 is then placed. The mounting area 23 is located between the extension 22 of the leaf spring 16 and the remaining part of the leaf spring 16. The safety strap 19 is attached to the leaf spring 16 with fastening elements 21, 24 in the mounting area 23 and / or around the loop 17.

The fastening elements 21, 24 can for instance consist of rivets or screws. As shown in Fig. 2, the shaft bracket 7 is then tightened over the mounting area 23 and thereby further tightens the safety strap 19 between the plate 32 and the leaf spring 16, and between the wheel axle 4 and the leaf spring 16. The figure also shows the bearing 13 and the bolt 12 passing through the bearing 13.

The spring link 6 may also comprise a clamping unit 20 which connects a lower and an upper part of the safety strap 19. The clamping unit 20 functions as a running loop around the spring link loop 17, and is only fixedly connected to either of the lower and the upper part of the safety strap 19. of the lower or upper part of the safety band 19 which is not fixedly connected to the clamping unit 20 is allowed to move in the opening of the clamping unit 20 during spring movement or in case of breakage of the spring link 6. The clamping unit 20 may for example comprise a jumper locked with a screw connection 27 or by welding. As shown in the figures, the clamping unit 20 is placed adjacent to the loop 17. If a fracture occurs on the leaf spring in the vicinity of the loop 17, the leaf spring 16 is prevented from passing over the loop 17. The leaf spring 16 is thus prevented from moving relative to the loop 17 position more than a play between the loop 17 and the safety strap 19 and possible extension of the safety strap 19 allows. The length of the spring link 6 can then be substantially maintained, and also the stability of the spring link 6 in the vertical vehicle direction dt. These properties can be improved by designing the safety band 19 tightly around the leaf spring 16 so that there is no or only a small play between the safety band 19 and the leaf spring 16 around the loop 17 on the leaf spring 16. A further way to improve these properties is to place the clamping unit 20 so close to the loop 17 as possible.

The safety belt 19 can, for example, be made of flat iron, or steel with good tensile strength. It has a thickness of between 1-5 mm, for example 2, 3 or 4 mm. The width of the safety belt 19 may, for example, correspond to the width of the leaf spring 16. According to one embodiment, the safety belt 19 is manufactured in one unit. The leaf spring 16 can be made of, for example, spring steel, steel or composite.

The present invention is not limited to the embodiments described above. Various alternatives, modifications and equivalents can be used. Therefore, the above-mentioned embodiments do not limit the scope of the invention, which is defined by the appended claims.

Claims (5)

Patent claims A spring suspension (3) for a wheel axle (4) of a vehicle (1), the spring suspension (3) comprising a leaf spring (16) extending substantially in a horizontal vehicle direction dhoch mounted to a vehicle body (8) on the vehicle (1) via a spring bracket (5) housing a bearing (13), which leaf spring (16) is formed with a loop (17) at one end of it facing the spring bracket (5) and is mounted to the spring bracket (5) via a bolt (12) extending in a substantially transverse vehicle direction dt through the bearing (13) and through the loop (17) of the leaf spring (16) which at its other end is attached to the wheel axle (4) via a shaft bracket (7), the leaf spring (16) is a single-leaf spring and mounted at an upward angle in a direction from the axle bracket (7) to the spring bracket (5) and the loop (17) facing downwards in a vertical vehicle direction dv, characterized in that the leaf spring (16) comprises a safety band ( 19) extending from a mounting area (23) on the leaf spring (16) within which a mounting area (23) the leaf spring (16) is adapted to be mounted to the wheel axle (4) and along a first side (25) of the leaf spring (16) to enclose the loop (17) and further along a second side (26) of the leaf spring (16) to the mounting area (23) of the leaf spring (16) and in that the first and second sides (25, 26) are opposite sides of the leaf spring (16). The spring suspension (3) according to claim 1, wherein the leaf spring (16) is rigidly mounted to the spring bracket (5) in the transverse vehicle direction dt. The spring suspension (3) according to any one of the preceding claims, wherein the bearing (13) is a rubber bearing. The spring suspension (3) according to claim 1, wherein the leaf spring (16) comprises a clamping unit (20) which connects the safety band (19) to the leaf spring The spring suspension (3) according to any one of the preceding claims, wherein the loop (17) has a substantially circular shape.