DE4142587C2 - Subframe with pivoting wishbones - Google Patents

Description

The invention relates to a subframe with pivotable articulated wishbones for the front wheels of a Motor vehicle called in the preamble of claim 1 ten way, as for example from EP 0 265 675 A1 or from DE 25 36 060 A1 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 wishbones pivotally attached to it are usually designed to be comparatively stiff because this is advantageous for the vehicle's driving dynamics. The handlebar bearings themselves generally contain rubber-elastic elements, on the one hand to contribute to road-related noise and vibrations from the vehicle interior to keep away, and through their special dimensioning on the other constructively influence the Self-steering behavior of the vehicle can be taken.

The front end structure of modern passenger vehicles is designed in such a way that Appropriate training and dimensioning of the side members of the vehicle body at one Head-on collision the passenger compartment remains as undeformed as possible, the front end on the other hand, is defined deformed. In this way, an essential part becomes in the event of a collision the kinetic energy of the vehicle in the front end is converted into deformation energy, whereby the restraining forces acting on the buckled vehicle occupants reduced accordingly and ultimately their risk of injury is significantly reduced.

From DE-C1-38 00 944 is a storage arrangement for a one-piece wishbone Wheel suspension known, in which the wishbone has a front and a rear Bearing element is attached to a frame structure. In the event of a crash, the rear one Bearing element a complete decoupling of the wishbone from the frame structure a separation at this point. This may cause the deformation of frame areas between the bearing elements are made softer, but this is done in the wishbone existing energy absorption capacity is lost or the wishbone experiences at most an uncontrolled deformation while it is dissipated under the vehicle body.

Furthermore, EP-A2-0 284 049 discloses a rubber bearing for the rear bearing element Front suspension for absorption of vibrations occurring in the transverse direction of the vehicle due to unbalance excitation on the front wheels. The displacement path remains in the area  usual longitudinal spring effects and is for a reduction of the maximum shock pulse in Crash case not sufficient.

The invention is therefore based on the issue of a subframe with pivotable thereon Articulated wishbones according to the preamble of claim 1 to create the with optimal use of the deformation potential of the subframe as well as the Wishbones a reduction in the occupants of a vehicle provided with it maximum accelerations allowed.

This problem is solved by a subframe of the type mentioned above, in which the rear link bearing is designed and dimensioned such that the wishbone in the case of forces acting on it in the longitudinal direction of the vehicle by one in comparison to conventional ones Longitudinal spring effects far extending dimension in the vehicle longitudinal direction relative to the rigid with the subframe and / or the vehicle body bolted rear bearing bolts in the rear link bearing is displaceable by a defined path length s *, the Limitation of displacement of the wishbone compared to the rear bearing pin limited is.

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

Based on the embodiments shown in the drawing, the invention 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 principle deformation force / deformation path diagram of a conventional subframe / wishbone assembly

Fig. 7 shows a corresponding principle deformation 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 manner in the lower area of 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 handlebar 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 whose orientation 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, is not only used for pivotable articulation of the 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 265 675 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 wishbone 2 during a head-on collision of the vehicle temporarily in the area of the rear link bearing 4 in the vehicle are decoupled in the longitudinal direction from the subframe 1 and can move here in the vehicle longitudinal direction relative to the rear bearing bolt 41 which is rigidly screwed 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 seat belt 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 265 675 known conventional rubber metal bearings realized that the ent speaking constructive design of its receptacle 43 in the three wishbones 2 is given the possibility of lying at a certain, above driving forces occurring longitudinal force from its constructive given operational loosen position within the wishbone 2 and slide into an adjacent 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 limited 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 takes later in Fig. 3 with 41 * spatial position.

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 Lagerauf measure 43 slide into it, without this already 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.

At a deformation of the front body structure as a result of a frontal collision of the vehicle so, the Längsverfor of the auxiliary frame 1 and the triangular suspension arm 2, the auxiliary frame / wishbone assembly 1/2 does not mung resistors at the same time effective from the start, but initially only the auxiliary frame 1, which then after completion 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. on 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 the buckled vehicle occupants from before is part.

The aforementioned temporary decoupling of the wishbone 2 from the subframe can also be realized in the manner shown in Figs. 4 and 5 prieni pieni. 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 first 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 or long hole-shaped receptacle 43 of the wishbone arm 2 , as well as a conventional cylindrical inner sleeve 48 for receiving the rear bearing bolt 41, which is not shown 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 occupies 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 marked with 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 / according to good quality to realize the invention (Fig. 7) Dreiecksquerlen ker assembly 1/2.

In a subframe / wishbone assembly of known type, the longitudinal deformation force F _{B of} the structural unit first increases very quickly to a maximum value which is much larger than the maximum value of the longitudinal deformation force F _{H of} the auxiliary frame alone. This is apparently due to the fact that 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 effectively simultaneously from the beginning. 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 FIG. 7 seen, wishbone assembly subframe-1/2 gives other hand, in a accordance with the OF INVENTION dung noticeably lower maximum value of the longitudinal deformation force F _B of this assembly and the longitudinal deformation behavior of the structural unit is made uniform over the deformation s of this unit, which depends in detail on the dimensioning and counter-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 aforesaid decoupling between the auxiliary frame 1 and wishbone 2 straight then wound is consumed as when the critical longitudinal deformation force of the be already längsverformenden subframe 1 is exceeded and the longitudinal deformation force F _H begins to fall 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 in time, at which the relative free movement speed between the rear bearing pin 41 and the area of the wishbone arm 2 receiving the rear link bearing 4 is consumed, the wishbone arm 2 also participate in the energy conversion of the subframe / 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 - at an almost constant level persists, which corresponds approximately to the maximum value of the longitudinal deformation force F _{H of} the subframe 1 alone 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 wishbone half whereby the increase of the passenger cell delay is reduced in an advantageous manner, in a frontal impact, by the construction unit support frame / generates an energy conversion at a low power level over a longer deformation path.

Claims (3)

1. Subframe ( 1 ) with pivotally articulated wishbones ( 2 ) for the front wheels ( 5 ) of a motor vehicle, each of which - viewed in the direction of travel - a front link bearing ( 3 ) and a spaced rear link bearing ( 4 ) with a rubber-elastic bearing element ( 42 ) and with a rigidly screwed to the subframe ( 1 ), at least approximately vertically extending bearing pin ( 41 ), which preferably also serves for releasably fastening the subframe ( 1 ) to the vehicle body, characterized in that the rear link bearing ( 4th ) is designed and dimensioned in such a way that the wishbone arm ( 2 ) in the vehicle longitudinal direction acts on it by a far greater amount in the vehicle longitudinal direction than conventional longitudinal spring effects relative to the rear screwed rigidly to the subframe ( 1 ) and / or the vehicle body Bearing pin ( 41 ) in the rear link bearing ( 4th ) is displaceable by a defined path length (s *), the displacement path of the wishbone arm ( 2 ) being limited in relation to the rear bearing pin ( 41 ). 2. Subframe according to claim 1, characterized in that the rear link bearing ( 4 ) contains a known rubber-metal bearing with an inner sleeve penetrated by the rear bearing pin ( 41 ) and an outer sleeve connected to the latter by a rubber-elastic bearing element ( 42 ), and in that the triangular wishbone ( 2 ) for fastening the rubber-metal bearing has a slot-like bearing receptacle ( 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 ) separate front clearance ( 45 ) into which the rubber-metal bearing can be inserted after the waist-shaped constriction ( 46 ) has been widened if the longitudinal forces effective in the wishbone arm ( 2 ) in the event of a frontal impact exceed a predetermined value. 3. Subframe according to claim 1, characterized in that the rear link bearing ( 4 ) is an elongated in cross-section rubber-metal bearing with a rear bearing bolt ( 41 ) receiving cylindrical inner sleeve ( 48 ) and an outer sleeve connected to this via a rubber-elastic bearing element ( 42 ) ( 47 ) has an elliptical cross-section, the inner sleeve ( 48 ) being arranged eccentrically in the rear region of the outer sleeve ( 47 ), and the outer sleeve ( 47 ) being pressed into a slot-like or elliptical-like bearing seat ( 43 ) of the triangular control arm ( 2 ).