Spring assembly for a vehicle suspension

Abstract

The disclosure concerns a spring assembly with a leaf spring. The leaf spring extends in a vehicle longitudinal axis, supports a vehicle axle and is connected at least indirectly to a vehicle superstructure at a front end and at a rear end. In order to provide a wheel suspension with advantageous springing and damping behavior that is optimized with regard to weight and complexity, according to the disclosure it is provided that at least one damping region, which is at least partially fluid-filled, is integrated in the leaf spring.

Claims

1. A spring assembly comprising: a leaf spring that extends in a vehicle longitudinal axis, supports a vehicle axle and is connected at least indirectly to a vehicle superstructure at a front end and at a rear end, the leaf spring having at least one damping region comprising a plurality of at least partially fluid-filled recesses integrated in the leaf spring and following each other in an extension direction of the leaf spring, wherein at least one of the recesses comprises two reservoir regions connected by a connecting channel constricted at least in portions.

2. The spring assembly as claimed in claim 1, wherein the at least one damping region includes an electro-rheological fluid.

3. The spring assembly as claimed in claim 1, wherein at least some of the plurality of recesses are formed elongate and run at an angle of at least 45° to the extension direction.

4. The spring assembly as claimed in claim 1, wherein in at least some of the plurality of recesses and the reservoir regions are spaced apart along a vehicle vertical axis.

5. The spring assembly as claimed in claim 1, wherein a distance between two recesses of the plurality of recesses is smaller than a thickness of the leaf spring transverse to the extension direction.

6. The spring assembly as claimed in claim 1, wherein the leaf spring has a spring portion that is concave at least in portions and adjoined by a connecting arm running at an angle thereto, and the connecting arm is connected pivotably to the vehicle superstructure.

7. The spring assembly as claimed in claim 6, wherein the connecting arm is formed by a connecting portion configured integrally with the spring portion.

8. A vehicle comprising: a wheel suspension having a spring assembly with a leaf spring that extends in a vehicle longitudinal axis, supports a vehicle axle and is connected at least indirectly to a vehicle superstructure at a front end and at a rear end, wherein at least one damping region is integrated in the leaf spring, the damping region comprising a plurality of at least partially fluid-filled recesses that follow each other in an extension direction of the leaf spring, wherein at least one of the plurality of recesses comprises two reservoir regions connected by a channel constricted at least in portions; and a connecting arm connected pivotably with the vehicle superstructure and running at an angle with respect to and adjoining a spring portion of the leaf spring that is concave at least in portions.

9. The vehicle as claimed in claim 8, wherein at least some of the plurality of at least partially fluid-filled recesses are formed elongate and run at an angle of at least 45° to the extension direction.

10. The vehicle as claimed in claim 8, wherein in at least some of the plurality of at least partially fluid-filled recesses and the reservoir regions are spaced apart along a vehicle vertical axis.

11. The vehicle as claimed in claim 8, wherein a distance between two recesses of the plurality of at least partially fluid-filled recesses is smaller than a thickness of the leaf spring transverse to the extension direction.

12. A vehicle wheel suspension comprising: a spring assembly with a leaf spring that extends in a vehicle longitudinal axis, supports a vehicle axle, and is connected at least indirectly to a vehicle superstructure at a front end and at a rear end; at least one damping region integrated in the leaf spring and comprising a plurality of recesses at least partially filled with a magneto-rheological fluid, wherein the recesses follow each other in an extension direction of the leaf spring, and wherein at least one of the recesses comprises two reservoir regions connected by a channel constricted at least in portions; and a connecting arm being connected pivotably to the vehicle superstructure and running at an angle with respect to and adjoining a spring portion of the leaf spring that is concave at least in portions.

13. The vehicle wheel suspension as claimed in claim 12, wherein at least some of the plurality of at least partially filled recesses are formed elongate and run at an angle of at least 45° to the extension direction.

14. The vehicle wheel suspension as claimed in claim 12, wherein in at least some of the plurality of at least partially filled recesses and the reservoir regions are spaced apart along a vehicle vertical axis.

15. The vehicle wheel suspension as claimed in claim 12, wherein a distance between two recesses of the plurality of at least partially filled recesses is smaller than a thickness of the leaf spring transverse to the extension direction.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 depicts a side view of a spring assembly according to the disclosure in a first embodiment;

(2) FIG. 2 depicts a sectional depiction of extract II from FIG. 1;

(3) FIG. 3 depicts a sectional depiction corresponding to FIG. 2 in a second embodiment; and

(4) FIG. 4 depicts a side view of the spring assembly according to the disclosure in a third embodiment.

DETAILED DESCRIPTION

(5) As required, detailed embodiments of the present disclosure are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the disclosure that may be embodied in various and alternative forms. The figures are not necessarily to scale; some features may be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the present disclosure.

(6) In the various figures, the same parts always carry the same reference signs so these are usually only described once.

(7) FIG. 1 shows a first embodiment of a spring assembly 1, which may be used for example in a truck. A rear axle 20, formed as a rigid axle, is connected to a vehicle superstructure (not shown) by a leaf spring 2. While the rear axle 20 extends parallel to the Y-axis, the leaf spring 2 extends along the X-axis, predominantly not parallel thereto but with a concave curvature within the X-Z plane. The leaf spring 2 has a concave, spring portion 2.1, a first bearing eye 2.4 at a front end 2.2, and a second bearing eye 2.5 at a rear end 2.3. A first rubber-metal bushing 4 is pressed into the first bearing eye 2.4, via which the leaf spring 2 is connected pivotably to the vehicle superstructure. A second rubber-metal bushing 5 is pressed into the second bearing eye 2.5, via which the leaf spring 2 is connected pivotably to a connecting arm 3, which is made e.g. from steel and is in turn connected pivotably to the vehicle superstructure. The function of the connecting arm 3 is to allow for a change in distance between the ends 2.2, 2.3 on deformation of the leaf spring 2.

(8) The leaf spring 2 is connected to the rear axle 20 via a clamping device 6. A lower clamping element 7 is clamped to an upper clamping element 8 by spring clamps 9 and nuts 10 assigned thereto, and at the same time welded to the rear axle 20. Both clamping elements 7, 8 in this case consist of steel. The leaf spring 2 is clamped between the clamping elements 7, 8 with the interposition of damper cushions 11, 12, which are made of rubber.

(9) FIG. 2 shows a sectional drawing in the X-Z plane and depicts a portion of the leaf spring 2. Above and below the leaf spring 2, a first metal layer 13 and a second metal layer 14 can be seen, between which a damping region 15 is arranged. The latter is partially filled with an electro-rheological fluid or a magneto-rheological fluid, wherein a more, precise, inner structure of the damping region 15 is not shown. The metal layers 13, 14 influence an elasticity or stiffness of the leaf spring, and thus contribute directly to spring behavior. It is also provided that the metal layers 13, 14 may be electrically charged (by a voltage source not shown here). In the case of an electro-rheological fluid in the damping region 15, a voltage may be applied between the first metal layer 13 and the second metal layer 14, so that an electrical field is produced inside the damping region 15. In the case of a magneto-rheological fluid in the damping region 15, it is provided that current flows through at least one, and preferably both, metal layers 13, 14, whereby a magnetic field is produced inside the damping region 15. In any case, the rheological properties of the fluid, in particular viscosity, are changed by a resulting field.

(10) On suspension compression of the rear axle 20, the leaf spring 2 is deformed, which affects the damping region 15. The fluid enclosed therein is expanded, compressed and/or displaced by this deformation. These processes lead to kinetic energy being converted into heat, and hence to a damping of vibration behavior. An intensity of damping may be influenced by viscosity of the fluid and hence by an applied electrical or magnetic field. However, the elasticity or stiffness of the leaf spring 2 is also influenced by the viscosity of the fluid. Thus, at high viscosity, the fluid behaves more like a solid body, whereby in general a stiffness of the leaf spring 2 is increased. Thus, it is possible to adjust both the stiffness of the leaf spring 2 and leaf spring damping by adjusting the electrical or magnetic field.

(11) FIG. 3 shows a sectional drawing corresponding to FIG. 2 in an alternative embodiment of the leaf spring 2. In this case, practically an entire volume of the leaf spring 2 is formed by a damping region 15, which however has a specific structure. A series of recesses 16 is formed inside a solid body 2.6 made of fiber-reinforced plastic. Each of the recesses 16 is formed elongate, transversely or perpendicularly to an extension direction A of the leaf spring 2. More precisely, the recesses 16 are formed following a running direction B, which runs at an angle of 90° to the extension direction A of the leaf spring 2. In the present example, all recesses 16 are formed identically. A distance between two recesses 16 in the present example amounts to around 20 to 25% of a thickness of the leaf spring 2, i.e. its dimension transversely to the running direction A. At an end, each recess 16 has an upper reservoir region 16.1 and a lower reservoir region 16.3, which are connected together by a straight connecting channel 16.2. The reservoir regions 16.1, 16.3 are widened in comparison with the connecting channel 16.2, or the connecting channel 16.2 is constricted relative to the reservoir regions 16.1, 16.3. A dimension of the reservoir regions 16.1, 16.3 transversely to the running direction B is around twice that of the connecting channel 16.2. The reservoir regions 16.1, 16.3 are formed spherical, and the connecting channel 16.2 has a circular cross-section. Each recess 16 is filled with a hydraulic fluid, wherein preferably no air or other gases are enclosed. During a production process of the leaf spring 2, the hydraulic fluid may be inserted through an opening, which is connected by substance bonding to the spring body 2.6 via a closing element.

(12) On suspension compression of the leaf spring 2, an upper part of the spring body 2.6 (in the direction of the Z-axis) undergoes an expansion while a lower part undergoes a compression. This leads firstly to a resetting, spring force, and secondly the respective lower reservoir region 16.3 is compressed while the reservoir region 16.1 is expanded. This leads to fluid flowing through the connecting channel 16.2 into the upper reservoir region 16.1, wherein because of a comparatively narrow cross-section of the connecting channel 16.2, a strong friction occurs inside the fluid and between the fluid and the wall of the connecting channel 16.2. This in turn leads to part of kinetic energy being converted into heat, and hence a vibration of the leaf spring 2 (and hence of the spring assembly 1) is reduced. On suspension extension, the upper reservoir region 16.1 is compressed and the lower reservoir region 16.3 expanded, whereby again fluid flows through the connecting channel 16.2. Here again, kinetic energy is converted into heat and undesirable vibration behavior is reduced.

(13) Although a configuration in FIG. 3 here depicts an exemplary embodiment separate from that of FIG. 2, it may be sensible to combine the two embodiments in that the damping region 15 shown in FIG. 2 is structured as shown in FIG. 3.

(14) FIG. 4 shows a further embodiment of the spring assembly 1, a structure of which resembles that of the embodiment shown in FIG. 1 and to this extent is not described again. However, in this embodiment, there is no separate connecting arm 3, but a concave spring portion 2.1 is adjoined by a connecting portion 2.7, which runs at an angle of approximately 90° thereto and on which the rear bearing eye 2.5 is formed, in which the second rubber-metal bushing 5 is pressed. The connecting portion 2.7 is connected to the vehicle superstructure via the second, rubber-metal bushing 5. This means that in this case, a function of the connecting arm 3 is integrated in the leaf spring 2. A necessary length compensation, which must be provided for suspension compression and extension, takes place via an elastic deformation of the connecting portion 2.7 and an elastic kinking of the connecting portion 2.7 relative to the spring portion 2.1. With the leaf spring 2 shown in FIG. 4, the damping mechanisms according to FIGS. 2 and 3, or mixtures thereof may be provided. Optionally, it is possible that a damping region 15 is restricted to the spring portion 2.1, while the connecting portion 2.7 is formed for example as a solid body of fiber composite material.

(15) While exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms of the disclosure. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the disclosure. Additionally, the features of various implementing embodiments may be combined to form further embodiments of the disclosure.