Spring for use in conjunction with a vehicle

Abstract

A spring for use in conjunction with a vehicle, in particular a leaf spring (1), preferably a parabolic spring, has a single-part spring leaf (12) made of steel, in particular spring steel, having a central region (2) and two adjoining edge regions (4a, 4b), wherein the edge regions (4a, 4b) each have an end region (5a, 5b), the end regions (5a, 5b) can each be connected to a chassis in a stationary manner via a rolled eye (11), and the total length of the spring when installed on the vehicle is substantially unchangeable in all load states. In the unloaded state, the spring leaf (12) has two bending sections (13, 14), which each have a curvature with a curvature direction, wherein the curvature directions of the two bending sections (13, 14) are opposed, and the two bending sections (13, 14) merge into each other in the region of a turning point (15). The first bending section (13) is a vertical spring section and runs from the end region (5a) of the first edge region (4a) via the central region (2) to the turning point (15). The second bending section (14) is a horizontal and vertical spring section and runs from the turning point (15) to the end region (5b) of the second edge region (4b).

Claims

1. A spring for use in conjunction with a motor vehicle, wherein the spring is a leaf spring, which has a one-part spring leaf made of spring steel, with a central region and two adjacent edge regions, wherein the edge regions each have an end region, wherein the end regions can each be connected to a chassis in a stationary manner via a rolled eye, wherein each rolled eye is translatory fixed and rotational in relation to the chassis, and wherein the total length of the spring in an installed state on the vehicle is substantially unchangeable in all load states, wherein in the unloaded state, the spring leaf has precisely two bending sections which are a first bending section and a second bending section, each having a curvature with a curvature direction, wherein the curvature direction of the first bending section and the curvature direction of the second bending section are opposed and wherein the first bending section and the second bending section merge into each other in the region of a turning point, and wherein the first bending section is a vertical spring section and runs from the end region of the first edge region via the central region to the turning point and the second bending section is a horizontal and vertical spring section and runs from the turning point to the end region of the second edge region.

2. A spring according to claim 1, wherein the first bending section is longer than the second bending section and that the second bending section is more markedly curved than the first bending section.

3. A spring according to claim 1, wherein the first edge region has an essentially constant effective length from the end region to the central region in all load states and that the effective length of the section of the first bending section running from the central region to the turning point becomes greater with increasing load, so that a compressive force is exerted on the second bending section.

4. A spring according to claim 1, wherein the rolled eye for connecting the end region of the second edge region to the chassis is fastened rotatably to the chassis.

5. A spring according to claim 4, wherein the rolled eye can be fastened to the chassis so as to be rotatable about a rotary axis, wherein a neutral fibre of the spring is spaced apart from the rotary axis.

6. A spring according to claim 1, wherein a bearing bush is arranged in each rolled eye, said bearing bush acting in a rotationally elastic manner.

7. A spring according to claim 1, wherein the second edge region runs from the central region via the turning point to a vertex and from the vertex continuously, and essentially straight, to the end region.

8. A spring according to claim 7, wherein the section running from the vertex to the end region of the second edge region and the section running from the vertex in the direction of the central region are arranged in the region of the vertex at an angle (α) of greater than 80° with respect to one another.

9. A spring according to claim 8, wherein with increasing load, the angle (α) at first remains essentially the same and then increases.

10. The spring of claim 8, wherein the angle (α) is 100 to 150°, or 120 to 140°, or 130°.

11. A spring according to claim 1, wherein the first bending section has a lesser bending strength than the second bending section.

12. A spring according to claim 1, wherein the rolled eyes each have an end face.

13. A spring according to claim 12, wherein the rolled eyes are deflected starting from the respective edge region and run essentially in a circular shape, and that a gap is present between the surface of the edge region and the end face of each rolled eye.

14. A spring according to claim 13, wherein the rolled eyes run on the same side of the spring, on the upper side of the edge region of the spring in an installed state or on the lower side of the edge region of the spring in an installed state.

15. A spring according to claim 1, wherein the central region comprises a clamping region, which can be connected to a wheel axle or a wheel axle bolt by means of a connection device, by one or more U-shaped bolts or moulded parts encompassing the spring in the clamping region.

16. The spring of claim 1 wherein the spring is a parabolic leaf spring.

17. The spring of claim 1, wherein the first bending section runs from the end region of the first edge region through the central region to the turning point.

Description

(1) The invention is explained in greater detail with the aid of an example of embodiment according to the drawings. In the figures:

(2) FIG. 1 shows a generic, single-part spring made of spring steel,

(3) FIG. 2 shows an embodiment of a single-part spring made of spring steel according to the invention,

(4) FIG. 3 shows an embodiment of a single-part spring made of spring steel according to the invention in combination with bearing bushes and an auxiliary leaf and

(5) FIG. 4 shows a detail view in the region of a rolled eye.

(6) FIG. 1 represents a known leaf spring 1 made of spring steel in an essentially unloaded state. The leaf spring 1 has a central region 2 with a central axis 3 and two edge regions 4. The edge regions 4 each have an end region 5. The right-hand edge region 4 has, adjacent to central region 2, a first curvature region 6 with a first curvature direction and a first vertex 7, wherein the first vertex 7 is located on the lower side of central axis 3. This edge region 4 has, adjoining in the direction of its end region 5, a second curvature region 8 with a second curvature direction and a second vertex 9, wherein the second curvature direction is opposed to the first curvature direction and wherein second vertex 9 is located on the upper side of central axis 3. The end region 5 of the right-hand edge region 4 is inclined away from the second vertex 9 towards the side on which the central region 2 is located. The edge regions 5 each have a rolled eye 11 for connecting the leaf spring 1 to a chassis of a vehicle.

(7) The upper side of leaf spring 1 represented in FIG. 1 is its upper side 10, which points towards the vehicle chassis in the installed position in the vehicle.

(8) In the region of first curvature region 6, a force distribution occurs in particular due to shearing forces, which force distribution is accompanied by the risk of a high degree of wear and therefore undesired material fatigue. In addition, first curvature region 6 leads to a reduction in the ground clearance, as a result of which the risk of damage when driving over an obstruction, e.g. a curbstone, is increased.

(9) FIGS. 2 and 3 represent embodiments of a spring leaf 1 according to the invention as a parabolic spring for use in conjunction with a motor vehicle. The leaf spring 1, which can be produced in a heat deformation process, has a one-part spring leaf 12 made of spring steel with a central region 2 and two adjacent edge regions 4a, 4b. The edge regions 4a, 4b each have an end region 5a, 5b, wherein the end regions 5a, 5b can each be connected to a chassis in a stationary manner via a rolled eye 11 and wherein the total length of the leaf spring 1, i.e. the distance between the two eyes 11, when installed on the motor vehicle is substantially unchangeable in all load states.

(10) In the unloaded state, the spring leaf 12 has two bending sections 13, 14, wherein bending sections 13, 14 each have a curvature with a curvature direction, wherein the curvature direction of the two bending sections 13, 14 is opposed and wherein the two bending sections 13, 14 merge into each other in the region of a turning point 15. The first bending section 13 runs from the end region 5a of the first edge region 4a via the central region 2 to the turning point 15 and the second bending section 14 runs from the turning point 15 up to the end region 5b of the second edge region 4b. The second edge region 4b runs from the central region 2 via the turning point 15 to a vertex 16 and from the vertex 16 essentially straight to the end region 5b.

(11) The rolled eyes 11 can be fastened to the chassis via a bearing bush 18 so as to be rotatable about a rotary axis 17, wherein the neutral fibre of leaf spring 1 and the neutral bending fibre of edge regions 4a, 4b are each spaced apart from rotary axis 17. Both rolled eyes 11 run at upper side 10 of leaf spring 1.

(12) The central region 2 has a clamping region 19, the thickness (height) of which is greater than the thickness of the adjacent edge regions and which can be connected to a wheel axle or a wheel axle bolt for example by means of U-shaped bolts. The central region 2 has transition regions 20a, 20b between the clamping region 19 and the edge regions 4a, 4b adjacent to central region 2, in which transition regions the thickness of leaf spring 12 correspondingly increases or diminishes.

(13) The upper side of leaf spring 1 represented in FIGS. 2 and 3 is its upper side 10, which points towards the vehicle chassis in the installed position in the vehicle. Turning point 15 is arranged above central region 2 in the installed state on the vehicle in the presence of nominal load.

(14) As can best be seen in FIG. 4, rolled eyes 11 each have an end face 21. The rolled eyes 11 run in an essentially circular shape, wherein a gap 22 is present between upper the side 10 of the corresponding edge region 4a, 4b and the end face 21 of the rolled eyes 11.

(15) The drawbacks described in connection with the prior art (see FIG. 1) are removed with a leaf spring 1 according to the invention.

(16) In the case of motor vehicles, a distinction is made between cars (PKW) and lorries (LKW). In the case of lorries, a distinction is also made between light-weight lorries (“LLKW”, up to 7.5 t), medium-weight lorries (“LKW”, from 7.5 t to 12 t) and heavyweight lorries (“SLKW”, from 12 t). The demands with regard to the spring suspension or wheel suspension are in each case different on account of the loads to be transported. A spring according to the invention can be used with all known motor vehicles.