Patent Application
20190257381
The subject disclosure generally relates to suspension systems for motor vehicles and, more particularly, to a damper assembly that reduces shock tower loading.
Motor vehicles include suspension systems that may include springs, dampers and support members extending between a vehicle body or frame and a set of road wheels. The suspension system expands and contracts in a controlled manner, in order to cushion relative movement between the body and wheels, as the vehicle traverses uneven terrain. When driving on relatively well developed roadways, the components of the suspension system dissipate the forces generated by bumps, potholes and other road anomalies in a controlled manner that helps a driver to maintain control of the vehicle and that provides a comfortable driving environment for the driver and passengers.
In severe service, when a vehicle suspension is exposed to high-impact events, excessive loading on the suspension components may cause compression beyond a set of limits or beyond the designed operating range of the components. Excessive relative movement between the body and the road wheels (“jounce”) may lead to potentially damaging collisions between suspension components and other vehicle elements. To prevent such collisions, suspension systems employ impact load management systems to limit excessive jounce. Such systems typically include jounce bumper assemblies that engage and compress during severe impact events to provide a bottoming or limit to further suspension travel. Jounce bumper assemblies may be conveniently located within the body of a suspension strut or damper assembly. The assemblies will typically include a rigid striker surface coupled to an end-cap of a strut damper tube and a polyurethane foam-based or rubber jounce bumper coupled to an upper strut assembly mount. The striker surface and the jounce bumper are aligned along a common piston rod axis and are spaced apart so that, during an impact event, the jounce bumper and the striker surface engage, causing the bumper to deform along the piston rod axis in the direction of loading.
The configuration of load management systems such as that described, may provide a minimum cushioning effect from impact loads because of the rigidity of the striker surface and the limited capacity of the foam bumper to absorb associated energy. Striker surfaces, jounce bumpers and associated mounting hardware can receive the brunt of impact loads leading to damage. As a result, these and other similarly affected elements, including the chassis frame and vehicle body structure are, necessarily, designed with a stronger construction and greater mass than might otherwise be required if the jounce bumper assembly were capable of absorbing higher levels of energy.
Accordingly, it is desirable to provide a jounce bumper assembly, for managing impact loads in a vehicle suspension system, which provides improved energy absorption and reduced peak strain to minimize damage to the assembly and allow for the use of lighter weight vehicle structures.
In an embodiment, a damper assembly comprises a first portion having an upper mounting bracket and an upper spring seat, a second portion having a lower mounting bracket, a damper tube and a lower spring and a coil spring circumferentially disposed about the first and second portions and aligned substantially co-parallel with the damper tube. A strut rod is rigidly coupled to the upper mounting bracket at a first end and is slideably coupled to the damper tube at a second end. A load management system comprises a jounce bumper secured to the upper mounting bracket, a striker cap coupled to an end of the damper tube and having an opening through which the strut rod passes, and a jounce bumper restraint attached to the striker cap and comprising an annulus that extends axially away from the striker cap and towards the jounce bumper, to define a jounce bumper rate cup therein. The striker cap and the annulus axially and radially engage the jounce bumper during impact events.
In addition to one or more of the features described herein, in another exemplary embodiment, the striker cap comprises a flexible material such as a thermoplastic or thermosetting elastomeric polymer.
In addition to one or more of the features described herein, in another exemplary embodiment, the striker cap comprises a steel plate.
In addition to one or more of the features described herein, in another exemplary embodiment, the jounce bumper comprises a flexible material such as a polyurethane foam or rubber.
In addition to one or more of the features described herein, in another exemplary embodiment, the annulus of the jounce bumper restraint constrains a radially outward expansion of the jounce bumper during impact events.
In addition to one or more of the features described herein, in another exemplary embodiment, the restraint imposed upon the jounce bumper by the annulus of the jounce bumper restraint is through the imposition of a hoop stress opposed to the direction of expansion.
In addition to one or more of the features described herein, in another exemplary embodiment, a vehicle comprises a chassis, a body supported by the chassis and comprising sprung vehicle mass and a suspension system and wheels comprising un-sprung vehicle mass. The suspension system provides a damped and stabilized coupling between the sprung and the un-sprung vehicle mass and comprises a first portion having an upper mounting bracket and an upper spring seat and a second portion having a lower mounting bracket, a damper tube and a lower spring. A coil spring is circumferentially disposed about the first and second portions and aligned substantially co-parallel with the damper tube. A strut rod is rigidly coupled to the upper mounting bracket at a first end and slideably coupled to the damper tube at a second end. A load management system comprises a jounce bumper secured to the upper mounting bracket, a striker cap conformably coupled to an end of the damper tube and having an opening through which the strut rod passes, and a jounce bumper restraint attached to the striker cap and comprising an annulus that extends axially away from the striker cap and towards the jounce bumper, to define a jounce bumper rate cup therein. The striker cap and the annulus axially and radially engage the jounce bumper during impact events.
The above feature and advantages, and other features and advantages of the embodiments are readily apparent from the following detailed description when taken in connection with the accompanying drawings.
Other features, advantages and details appear, by way of example only in the following detailed description of embodiments, the detailed description referring to the drawings in which:
The following description is merely exemplary in nature and is not intended to limit the present disclosure, its application or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features.
Various embodiments described herein provide an impact load management system having a jounce bumper assembly for managing the impact load, (“jounce”) in a vehicular suspension. The jounce bumper assembly is suitable for limiting jounce between suspension members such as, for example, a vehicle body or frame and a set of road wheels (i.e. sprung and un-sprung vehicle masses). When integrated within a suspension strut assembly, the jounce bumper assembly includes a striker cap in axial alignment with a jounce bumper. The striker cap is configured to be coupled to, and to overlap, the upper end of a cylindrical mount, such as a damper tube or striker cap support, and includes features that both axially and radially restrain the jounce bumper upon compression under impact loading. During impact events, one or both of the striker cap and the jounce bumper may deformably engage thereby absorbing energy that is generated by the impact load.
Referring to
Referring to
The damper assembly 24 includes load management system 26 that absorbs energy and limits excess compression (“jounce”) of the suspension system 16 during impact events. The load management system 26 may include jounce bumper 28, an upper mount 66 that secures the jounce bumper to the upper mounting bracket 32 and a striker cap 68. Jounce bumper 28 may comprise any suitable flexible material such as, for example, polyurethane foam or rubber. Jounce bumper 28 is attached to upper mount 66 and is circumscribed about, and moves axially with, strut rod or piston rod 52. Striker cap 68 may comprise any suitable material such as, for example, a thermoplastic or thermosetting elastomeric polymer. In another embodiment, the striker cap 68 comprises a steel plate. Striker cap 68 is conformably coupled to the closed end 60 of the damper tube 42, moves axially in unison therewith, and has an opening 72 that is axially aligned with opening 58 in closed end 60 of the damper tube 42 to thereby circumscribe the strut rod 52. Attached to the striker cap 68 is jounce bumper restraint 80 comprising an annulus 82 that extends axially away from the striker cap 68 and towards the jounce bumper 28 to thereby define a jounce bumper rate cup 84. The jounce bumper restraint 80 may be attached to the striker cap 68 through a press-fit or other suitable method of attachment. During extreme jounce events striker cap 68 and annulus 82 are configured to engage jounce bumper 28. In an example, during operation, and with reference to
For severe impact events, wherein maximum deflection of the jounce bumper 28 is reached,
Referring to
While the above disclosure has been described with reference to exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from its scope. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the disclosure without departing from the essential scope thereof. Therefore, it is intended that the present disclosure not be limited to the particular embodiments disclosed, but will include all embodiments falling within the scope thereof.
