DE4142587A1 - Auxiliary frame for vehicle front suspension - makes use of three-cornered cross-member displaceable in relation to bearing bolt - Google Patents

Abstract

The auxiliary frame (1) is for a vehicle suspension with a displaceably attached three-cornered cross member (2) for the front wheels (5) having leading bearings (3) spaced from rear bearings (4) with elastic bearings element (42). The rear bearings are so formed and dimensioned that the three cornered components are displaceable in relation to the rear bearing bolts (41) which are rigidly attached to the auxiliary frame and/or the vehicle bodywork. USE/ADVNATAGE - Method of improving the deformation behaviour of the front section of a vehicle structure without adversely affecting the running dynamics.

Description

The invention relates to a subframe with pivoting articulated wishbones for the front wheels of one Motor vehicle called in the preamble of claim 1 ten way, as for example from EP-OS 02 65 675 or from DE-OS 25 36 060 is known.

Such subframes or subframes are in particular in modern mass-produced passenger vehicles widespread because with them on the one hand in other ways not suitable places of the vehicle u. a. Storage and other Support points for the pivotable articulation of wheel guides handlebars (e.g. trailing, oblique or wishbones) or for the attachment of the drive unit, d. H. the engine / transmission be unity can be created and because with them to at whose assembly, d. H. the installation or attachment of the drive unit gats and / or the wheel control arm etc. on the vehicle body is made considerably easier because the drive unit and wheel guide steering handlebar and possibly also the steering gear of the Vehicle steering can be pre-assembled on the subframe and the assembly unit thus created during the vehicle final assembly as a whole in one step in the vehicle can be built. If necessary, also during the pre-assembly the track of the wheels can already be set.  

The subframe and the pivoted wishbones are usually designed to be comparatively stiff because of this is advantageous for the driving dynamics of the vehicle. The handlebars Bearings themselves generally contain rubber-elastic elements, which on the one hand should contribute to road-related noise and keep vibrations away from the vehicle interior, and through on the other hand, their special dimensioning has a constructive influence the self-steering behavior of the vehicle can be taken.

The front end structure of modern passenger vehicles is i. a. designed such. B. u. a. through appropriate training and dimensioning the side members of the vehicle body that at ei After a head-on collision, the passenger compartment is as deformed as possible remains, but the front end is deformed in a defined manner. On this way, in the event of a collision, an essential part of the The kinetic energy of the vehicle in front of the car in deformation energy converted, which means that on the buckled driving Retain forces acting on the vehicle occupants accordingly and ultimately significantly reduced their risk of injury becomes.

Against this background, the invention is based on the object de, a subframe in the preamble of claim l mentioned type without disadvantages for the driving dynamics of the vehicle to further develop such that the deformation behavior of the front car structure of one equipped with such a subframe Vehicle is improved.

This object is achieved by the features of Pa claim 1 solved.

Advantageous refinements and developments of the invention are specified in the subclaims.

Based on some of the execution examples shown in the drawing games, the invention is explained in more detail below.  

Show in the drawing

Fig. 1 is a partially sectional view of an OF INVENTION to the invention the auxiliary frame with a pivotally articulated thereto wishbone in driving generating longitudinal direction seen

Fig. 2 shows the same arrangement in plan view,

Figure 3 is a plan view approximately, for example. To a suspension wishbone used therein according to a first exporting,

Fig. 4 is a plan view approximately on such a used therein wishbone according to a second exporting,

Fig. 5 is a plan view on a special case inserted rubber metal bearing,

Fig. 6 is a principled exemplary deformation force / Verfor mungsweg diagram of a conventional auxiliary frame / wishbone assembly,

Fig. 7 shows a corresponding principle Verfor mungs force / deformation path diagram of the inventive subframe / wishbone assembly.

The subframe arrangement shown in FIGS . 1 and 2 is part of an otherwise customary independent wheel suspension of the front wheels 5 of a passenger car. It has, as usual to the vehicle longitudinal direction substantially symmetrical subframe 1 , of which only the left part is shown and which is screwed in the usual manner with the vehicle body not shown. On the subframe 1 , which can also serve as an assembly support for the motor / transmission unit and / or the steering gear of the vehicle, wheel control arms in the form of triangular wishbones 2 are pivoted, with their free ends in the usual way in the lower area the wheel carrier 6 of the steerable front wheel 5 are articulated and serve together with egg nem strut 7 of the wheel guide. In the usual way arranged tie rods, stabilizers and drive half-shaft are not further numbered.

The pivotable articulation of the wishbone arm 2 on the auxiliary frame 1 takes place in each case via a — in the direction of travel — front link bearing 3 and a spaced-apart rear link bearing 4 . Both link bearings contain in the usual way rubber-elastic bearing elements 32 and 42 , which, among other things, keep the interior, road-related noise and / or vibrations away from the vehicle interior. The front link bearing 3 is, as usual, in the form of a radial bearing, the bearing pin 31 of which runs at least approximately horizontally and the orientation of which corresponds to the pivot axis of the wishbone arm 2 . The rear link bearing 4 , on the other hand, is designed as a vertically aligned bearing, the vertical bearing pin 41 of which, in the exemplary embodiment, not only serves to pivot the articulated wishbone on the subframe, but also, in a known manner, at the same time for fastening the subframe 1 to the vehicle body (not shown).

Subframe 1 and wishbone 2 are dimensioned so stiff in the usual way that the vehicle has good driving dynamics properties. The rubber metal bearings of the two Lenkerla ger 3 and 4 can in turn be dimensioned in the usual way and matched in their spring detection that the desired self-steering behavior is achieved.

Deviating from conventional subframe / wishbone arrangements of the z. B. from EP-OS 2 65 675 or DE-OS 25 36 060 known type, the rear link bearing 4 inventions according to the invention, however, each designed such that the triangular control arm 2 during a head-on collision of the vehicle temporarily in the area of the rear link bearing 4 in The vehicle is decoupled from the subframe 1 in the longitudinal direction and can move in the vehicle longitudinal direction relative to the rear bearing bolt 41 screwed rigidly to the subframe 1 and / or the vehicle body, by a path which goes far beyond the extent of conventional longitudinal spring effects.

This way, without affecting the good driving dynamic behavior necessary basic longitudinal stiffness a more favorable deformation behavior of the auxiliary frame men / wishbone arm assembly achieved. With a frontal as a result of this training, it will impact over a country energy deformation (movement / deformation energy) at a relatively low and almost constant level The resulting (deformation) force level causes the increase the passenger compartment deceleration - compared to vehicles with conventionally trained subframe / wishbone arm regulations - noticeably reduced, what is for the Verlet danger of the belted vehicle occupants works.

In in Figs. 1 to 3 shown a Ausführungsbei play a sub-frame assembly according to the invention is performed using a per se for this favorable deformation behavior of the subframe assembly. B. from DE-OS 2 65 675 known conventional rubber metal bearings realized, which is given by ent speaking constructive design of its receptacle 43 in the three wishbones 2, the given longitudinal force from its constructive given at a certain, above driving forces occurring forces to release operational position within the wishbone 2 and slide into an adjacent free space.

As the plan views of Figs. 2 and 3 possesses, the wishbone 2 for fastening of the circular cylindrical in the usual manner actual rubber metal bearing is not as üb Lich one of the rubber metal bearing enclosing circular recess (bearing shell o. Ä.) The outer circumference, but a long hole-like bearing receptacle 43 with a waist-shaped lacing 46 . The outer sleeve of the rubber metal bearing is pressed in the usual way firmly into a tied by the waist-shaped lacing 46 a partial circle area 44 of the bearing receptacle 43 , so that the bearing pin of the rear link bearing 4 later takes the spatial position numbered 41 in FIG. 3.

If the vehicle exceed the course of a frontal impact the here at introduced into the wishbone 2 longitudinal forces an inter alia, by the dimensions of the waist-shaped constriction against certain value that can rubber metal bearing held by the rigidly bolted to the auxiliary frame and the vehicle body support bolt 41 under expansion of the waist-shaped Constriction 46 in the adjacent free space 45 of the bearing 43 measure slide into it, without this also leading to egg ner longitudinal deformation of the wishbone 2 ; the three corner wishbones 2 is namely decoupled from the already longitudinally deforming subframe 1 in the area of the rear link bearing 4 . Only when the rubber metal bearing after passing through this free space 45 again tung with its outer sleeve in longitudinal Rich rests directly on the wishbone 2 and thereby the bearing receptacle 43 forms containing rear part of the triangle wishbone 2 with the quasi spatially fixed rear bearing pin 41 rigid in the vehicle longitudinal direction substantially functional unit , the wishbone 2 is deformed in the longitudinal direction.

In the event of a deformation of the front-end structure as a result of a frontal impact of the vehicle, the longitudinal deformation resistances of the subframe 1 and the wishbone 2 of the subframe / wishbone assembly 1/2 are not simultaneously effective from the outset, but initially only that of the subframe 1 , which then occurs after termination superimposed on the above-mentioned decoupling of the longitudinal deformation resistance of the three corner wishbones 2 .

This staggered participation in energy implementation, i. H. at the conversion of kinetic energy into deformation energy  to the fact that they occur in such a head-on collision de Delay of the passenger compartment in the area of participation of the Subframe assembly rises less than usual, what the protection of buckled vehicle occupants from before is part.

The aforementioned temporary decoupling of the wishbone arm 2 from the subframe can also be realized in the manner shown in Fig. 4 and prinzi pienhaft. In this exemplary embodiment, the actual rubber-metal bearing shown in FIG. 5 is designed from the rear link bearing 4 such that the wishbone wishbone in the event of a frontal impact of the vehicle in the event of a longitudinal deformation of the subframe 1 in the aforementioned manner without its own longitudinal deformation by a certain path in the vehicle longitudinal direction can move relative to the quasi-stationary rear bearing pin 41 .

In this exemplary embodiment, the actual rubber metal bearing contains an outer sleeve 47 of elliptical cross-section, which is pressed into a corresponding elliptical-like or long-hole-shaped receptacle 43 of the wishbone arm 2 , and a conventional cylindrical inner sleeve 48 for receiving the rear bearing bolt 41 ( not shown further here). The outer sleeve 47 and the eccentrically arranged inner sleeve 48 are connected to each other by an elongated rubber-elastic bearing element 42 which is dimensioned stiff for transverse forces, while it remains soft for longitudinal forces in the direction of travel. If the special rubber metal bearing shown in FIG. 5 is installed in the associated wishbone arm 2 according to FIG. 4, then the inner sleeve 48 spatially assumes a position in which the rear bearing bolt of the rear bolted to the subframe and / or to the vehicle body Handlebar bearing 4 similar to Fig. 3 within the triangular wishbone 2 or relative to this assumes a position labeled 41 . This - relative to the wishbone arm 2 - it maintains under the influence of longitudinal forces occurring during normal driving, apart from the usual longitudinal spring effects, whereas in the event of a frontal impact, due to the correspondingly dimensioned longitudinal softness of the rubber-elastic bearing element 42, it is similar to the exemplary embodiment according to FIG. 3 a certain way in the vehicle longitudinal direction relative to the wishbone 2 is displaceable before it forms a unit essentially rigid with this in the vehicle longitudinal direction.

From the longitudinal deformation force / deformation path diagrams F = f (s) shown in FIGS . 6 and 7, obtained from quasi-static tests, the different longitudinal deformation behavior of a subframe / wishbone assembly of known type ( FIG. 6) and a subframe / Dreiecksquerlen ker unit 1/2 according to the invention ( Fig. 7) can be seen qualitatively well.

In a subframe / wishbone assembly of known type, the longitudinal deformation force F _{B of} the structural unit initially increases very quickly to a maximum value which is very much greater than the maximum value of the longitudinal deformation force F _{H of} the auxiliary frame alone. This is apparently because the subframe in known subframe / wishbone assemblies is stiffened in the longitudinal direction by the or the articulated wishbone in the vehicle and the longitudinal deformation resistance of subframe and wishbones are effective from the beginning at the same time. As a result, a comparatively high longitudinal deformation resistance is initially effective in these known units, which leads to a correspondingly strong increase in deceleration of the passenger compartment if the se begins to deform in the event of a deformation of the front-end structure via the subframe unit on the obstacle to impact.

At a certain longitudinal deformation force, the auxiliary frame men-wishbone assembly ultimately breaks down and the longitudinal deformation force F _{B of} the unit drops.

As can be seen in FIG. 7, on the other hand, with a subframe wishbone assembly 1/2 according to the invention, a noticeably lower maximum value of the longitudinal deformation force F _{B of} this unit and the longitudinal deformation behavior of the unit is evened out via the deformation path s of this unit, what depends in detail on the dimensioning and against mutual coordination of the components involved subframe 1 , wishbone arm 2 and link bearing 4 .

The structural unit according to the invention on which the longitudinal deformation force / longitudinal deformation path diagram of FIG. 7 is based has been developed, for. B. dimensioned such that the above-mentioned decoupling between subframe 1 and wishbone arm 2 is just about honored when the critical longitudinal deformation force of the already longitudinally deforming subframe 1 is exceeded and its longitudinal deformation force F _H begins to decrease again. In the exemplary embodiment according to FIG. 7, it was assumed that this is the case when the subframe 1 is longitudinally deformed by the path s. From this point on, to the relative move freely ness between the rear bearing pin 41 and the rear link bearings 4-receiving region of the triangular transverse control arm is consumed 2, the wishbone 2 take part in the power conversion of the auxiliary frame / wishbone construction unit. Now their longitudinal deformation resistances also become effective. While the longitudinal deformation force F _{H of} the subframe 1 decreases, the longitudinal deformation forces F _{Q of} the triangular wishbone 2 increase , so that the resulting longitudinal deformation force F _{B of} the subframe assembly - assuming appropriate dimensioning and mutual coordination of the interacting components - is at an almost constant level persists, which corresponds approximately to the maximum value of the longitudinal deformation force F _{H of} the subframe 1 and is therefore noticeably lower than the maximum value of the longitudinal deformation force F _B occurring in known subframe / wishbone control arm assemblies.

In this way, an energy conversion at a low power level is generated in a frontal impact by the construction subframe / wishbone 1/2 over a longer deformation path, whereby the increase in passenger compartment deceleration is advantageously reduced.

Claims (3)

1. Subframe ( 1 ) with pivotally articulated triangular control arms ( 2 ) for the front wheels ( 5 ) of a motor vehicle, each one - seen in the direction of travel - vorde res handlebar bearing ( 3 ) and a spaced-apart rear link bearing ( 4 ) with rubber-elastic Bearing element ( 42 ) and with rigidly screwed to the subframe ( 1 ), at least approximately vertically running bearing pin ( 41 ), which also serves for releasably fastening the subframe ( 1 ) to the vehicle body before, preferably, characterized in that the rear link bearing ( 4 ) each because it is so designed and dimensioned that the three corner wishbones ( 2 ) in the longitudinal direction of the forces acting on it in comparison to the usual longitudinal spring effects far in the longitudinal direction of the vehicle relative to the rigid frame ( 1 ) and / or the rear rear bearing bolt ( 41 ) screwed to the vehicle body is displaceable. 2. Subframe according to claim 1, characterized in that the rear link bearing ( 4 ) a known rubber metal bearing with a through the rear bearing pin ( 41 ) penetrated by the inner sleeve and one with this by a rubber-elastic bearing element ( 42 ) verbun which contains the outer sleeve, and that the triangular wishbone ( 2 ) for fastening the rubber mimetal bearing has an elongated hole-like bearing seat ( 43 ) with a waist-shaped constriction ( 46 ), with a circular rear region ( 44 ) into which the outer sleeve of the rubber-metal bearing is pressed, and one of them through the waist-shaped constriction ( 46 ) separated in front of their free space ( 45 ) into which the rubber-metal bearing can be inserted after expansion of the waist-shaped constriction ( 46 ) when the effective longitudinal forces in the wishbone arm ( 2 ) at a frontal impact exceed a predetermined value. 3. Subframe according to claim 1, characterized in that the rear link bearing ( 4 ) an elongated in cross-section rubber metal bearing with a rear bearing pin ( 41 ) receiving cylindrical inner sleeves ( 48 ) and an outer sleeve connected to this via a rubber-elastic bearing element ( 42 ) ( 47 ) has an ellipse-like cross-section, the inner sleeve ( 48 ) being arranged eccentrically in the rear area of the outer sleeve ( 47 ), and that the outer sleeve ( 47 ) in a slot-like or elliptical bearing seat ( 43 ) of the wishbone arm ( 2 ) is pressed in.