The present invention relates to a rotary damper arrangement for a torsion bar. In particular, the invention relates to a rotary damper arrangement for a torsion bar of a vehicle, especially a motor vehicle.

Historically, torsion bars have been used, extensively, in cars for springing. Recently, however, their use has become increasingly scarce. Conventional coil- springing arrangements allow the co-axial positioning of viscous dampers inside the corresponding coil. When using a torsion bar, the suspension designer is forced to connect the damper to some other point of the suspension, thereby increasing the complexity of the arrangement.

Therefore, it is the object of the present invention to provide a rotary damper arrangement that may be attached co-axially to a torsion bar, has improved damping properties and allows an improved packaging of suspension modules comprising the rotary damper arrangement.

According to the invention, this object is achieved by a rotary damper arrangement as defined in independent claim 1. The dependent claims define preferred embodiments of the invention.

The invention provides a rotary damper arrangement for a torsion bar, which may be used in a suspension module of a motor vehicle, especially a car. A primary rotary motion of the torsion bar, onto which a coupling device, preferably in the form of a co-axial gear/ring, is rigidly fitted, induces damping through a coupling connection of the torsion bar to a cluster of primary wings or flaps and secondary wings, whereby the wing clusters rotate inside a fluid, preferably a viscous medium, sealed in a casing via the transmission of epicyclic planetary gears, which are coupled in mesh. The damping control can thus be performed in an active and adaptive manner.

According to a preferred embodiment, the wings rotate about axes and have such a form and shape on their outer surface, so that rotary motion can be transmitted by means of gear coupling, via the transmission of the rotation of the planetary gears, due to the primary rotation of the torsion bar, which rotates the coupling device fitted rigidly to the torsion bar. The shape and form of the primary wings that produce the damping in the viscous medium may be L-shaped and may have features such as ridges and slots etc. so that in cooperation with the secondary wings an optimal damping functionality is ensured within the confines of the space of the purposely designed casing.

The shape and arrangement of the primary wings and the secondary wings may be such that at least two secondary wings extend symmetrically from the respective primary wing under acute angles so that, when viewed in a direction along the axis of rotation, the wing cluster formed by the primary and secondary wings has the shape of the Greek letter Psi (Ψ). The number of the wing clusters and the associated epicyclic planetary gears depends on the design constraints and the shape and form of the casing, the boundary limits of motion of the torsion bar, and the form and location of support brackets of the rotary damper arrangement, whereby these parameters determine the exact shape, location and boundary limits of motion of the primary and secondary wings.

The shape and profiling of the wing clusters may be chosen to optimize the damping process inside the casing which preferably is filled with a viscous fluid under pressure.

The invention allows the positioning of a damper co-axially around a torsion bar, thereby improving packaging. When using the damper in a suspension module, a large number of suspension modules of this type can be packaged into a container for shipping to a final assembly location, whereby the invention allows to reduce the packaging space required as the external dimension of the damper defines the maximum width dimension of the corresponding suspension module.

In the following, a preferred embodiment of the invention will be described in more detail with reference to the accompanying drawing.

Fig. 1 shows a co-axial rotary damping arrangement, built around a torsion bar, according to an embodiment of the invention.

Figs. 2 and 3 show the rotary damping arrangement without an outer casing.

Fig. 4 shows an arrangement of primary wings (without secondary wings) of the rotary damper arrangement. Fig. 5 shows a more detailed view of the wing clusters of the rotary damping arrangement, while the wings are rotated by an angle.

Fig. 6 shows the wing clusters of Fig. 5 during their counter rotation (on their return motion).

Fig. 7 shows a lateral cross-sectional view of the wing clusters during their rotation and counter rotation.

Fig. 1 - Fig. 7 show a preferred embodiment of the invention. While this particular embodiment will be described in detail below, several modifications will be appreciated by a person skilled in the art so that the invention shall not be interpreted in a limited manner referring to the description and the drawings. Rather, the invention is defined by the appended claims.

In Figs. 1-7, reference numeral 1 designated a torsion bar, for example a torsion bar for a motor vehicle such as a car. The rotary damper arrangement comprises a damper casing 2 being filled with a fluid, preferably a viscous medium. A coupling device 3 is used to couple the rotary damper arrangement to the torsion bar 1 , whereby the coupling device may be formed by a ring/drive gear fitted rigidly onto the torsion bar 1 such that through this coupling device 3 a rotation of the torsion bar 1 is transferred or transmitted to the rotary damper arrangement.

The rotary damper arrangement comprises a plurality of wing clusters that are distributed in the circumferential direction of the arrangement. In the embodiment shown, the rotary damper arrangement comprises three equally spaced wing clusters, each comprising a primary wing or flap 5 and at least two secondary wings or flaps 6 attached to the respective primary wing 5. Alternatively, the wing clusters may be unequally spaced over the whole circumference of the torsion bar 1. The coupling device 3 is coupled to a plurality of epicyclic planetary gears/rings 4 with each planetary gear 4 being associated with one of the wing clusters such that a rotation of the respective planetary gear 4 drives the primary wing 5 of the respective wing cluster.

The primary wings 5 are arranged rotatable about rotation axes 9 that are supported at support brackets 10, 1 1. As can be seen in the drawing, the arrangement is preferably such that the rotation axes 9 of the primary wings is substantially parallel to the rotation axes 8 of the planetary gears 4 and the rotation axis 7 of the torsion bar 1. The support brackets 10, 1 1 have openings though which the torsion bar 1 extends and are arranged spaced from one another in the longitudinal direction of the torsion bar 1 such that the rotary damper arrangement with the casing 2 and the wing clusters arranged inside the casing is disposed between the support brackets 10, 11.

According to the preferred embodiment shown in the drawing, each wing cluster comprises two secondary wings 6 that extend from the respective primary wing 5 towards opposite sides of the primary wing 5. In particular, the arrangement is symmetrical with respect to the primary wing 5 such that the two secondary wings extend towards the radial direction of the rotary damper arrangement and form substantially the same acute angle with the primary wing 5. Alternatively, the secondary wings 6 may be arranged asymmetrically with respect to the primary wing 5.

The primary wings 5 and the secondary wings 6 are preferably plate-shaped and have flat surfaces. Alternatively, the wings may be provided with profiles, slots, ridges etc. depending on the individual application. As shown in the drawing, corner portions of the wings 5, 6 are truncated or rounded.

The secondary wings 6 may have a substantially rectangular shape, while according to the preferred embodiment the primary wings 5 have a substantially L-shape with a first portion being coupled with the respective planetary gear 4 and a second portion having a larger width than the first portion and being arranged spaced or at a distance from the torsion bar 1. The first portion of each primary wing 5 has together with the corresponding rotation axis 9 the function of a gear

The first support bracket 10 may have the shape of a ring with a plurality of fingers extending from the ring in the radial direction, each finger supporting one of the rotation axes 9. The second support bracket 1 1 may be ring-shaped so that each rotation axis 9 is held directly at the ring of the second support bracket 11.

The primary rotary motion of the torsion bar 1 causes through the rotation of the co- axial coupling device 3 the planetary gears 4 to counter rotate, as they are coupled together in mesh. In turn, the rotation of each planetary gear 4 causes the respective primary wing 5 to rotate due to the coupling of the gear 4 to the base of the primary wing 5 (see Fig. 1 , Fig. 5 and Fig. 7).

The damper device is located and secured inside an outer casing 12 (see Fig. 1 ). Damping is achieved inside the damper casing 2, in which the viscous medium is regulated in an active and adaptive manner (see Fig. 2).

The rigid and fixed casing 2 supports and locates the inner and outer supporting brackets 10 and 11 within the confines of the outer casing 12. The torsion bar 1 and the co-axial coupling device or drive ring/gear 3, which are rigidly fitted to each other, are coupled in mesh with the epicyclic planetary gears 4 which, in turn, drive the primary wings 5 (see Fig. 5). Each planetary gear 4 rotates about the rotation axis 8, and each primary wing 5 rotates about the rotation axis 9 (Fig. 7). The form, shape and location of the main or primary wings 5 are such to ensure optimal damping. As already discussed above, the primary wings 5 may have the form of a Greek capial letter Gamma (F) or may be L-shaped, as shown in Figure 4 and indicated by dotted lines. Damping is enhanced by the secondary wing surfaces of the secondary wings 6 (Fig. 5). In the embodiment outlined here, three sets of wing clusters are provided, whereby within each wing cluster the wings 5, 6 have the shape, orientation and arrangement similar to the Greek capital letter Psi (Ψ), as shown in Fig. 7. Alternatively, the number of the wing clusters used may be determined by the boundaries of the rotation of the torsion bar 1 , the shape and size of the casing 2, and the shape, form and size of the wings 5 and 6 in order to achieve optimal damping.

The primary wings 5 and/or the secondary wings 6 may have slots, holes, orifices, ridges or other features to improve or enhance the damping characteristics of the damper arrangement by increasing the vorticity of the motion of the fluid in the damper. In addition, the casing 2 may be designed in conformity with the profiling of the primary and secondary wings 6, 5 so that the shape of the casing 2 is chosen in close proximity to the profiling of the wings 5, 6. Depending on the individual application, the wings 5, 6 may be flexible, in close proximity to, or even in contact with the casing 2.