DE102006038921A1 - Subframe, particularly front axle subframe, for motor vehicle, has two longitudinal carriers beams aligned in vehicle longitudinal direction, and cross beam aligned in vehicle transverse direction - Google Patents

Abstract

The subframe (10) has two longitudinal carriers beams aligned in vehicle longitudinal direction (FL). A cross beam (16) aligned in vehicle transverse direction (FQ), is arranged between the two carriers beams (12,14). Both casting joint (18,20) are arranged between the carrier beams and the cross beam. Both longitudinal carriers beams and the cross beam are firmly connected with the corresponding joints. A bowl-shaped fixture element is arranged at both casting joints, which is firmly connected with the assigned casting joint.

Description

The The invention relates to a subframe for a motor vehicle according to the Preamble of claim 1 specified type.

such Also referred to as subframe subframe for a motor vehicle are off sufficiently well known in the art and in addition to a Uncoupling of disturbing influences the structure or the body of the motor vehicle also has the advantage that various vehicle components are easily accessible to it storable. Dependent on from the installation location on the motor vehicle, i. in the area of the front or Rear axle, the subframe are precisifying as a front axle auxiliary frame or Hinterachschilfsrahmen called.

It is also known, for reasons of weight, to manufacture the longitudinal and transverse beams of light metal, respectively aluminum or aluminum alloys, which form the frame structure of the subframe and firmly connect them to one another via so-called node elements or cast nodes made of a light metal casting material. Such a generic subframe for a motor vehicle is for example in the DE 198 22 731 A1 described.

Especially in the described embodiment of the subframe for a motor vehicle with longitudinal and crossbeams made of light metal with corresponding cast nodes made of a light metal material, such as. Cast aluminum or alloys thereof, proves the Subframe detrimental in terms of to be met Crash requirements. Will the subframe for a motor vehicle, and here specifically the front axle auxiliary frame, in an accident to convert crash energy used, the casting nodes tend to premature failure. As Experiments and simulations have shown in the event of an accident usually as extruded profiles of a light metal trained longitudinal and crossbeams sufficient strength to absorb the crash energy, while the force impulse acting on the casting knots first of all a "sideways turning away" and a subsequent sudden failure the casting node causes.

Of the Invention is based on the object, a subframe for a motor vehicle according to the preamble of claim 1 specified type while avoiding the said Disadvantages continue to form such that the risk of premature Failure of the cast nodes of the subframe in the event of an accident is significantly reduced.

These The object is achieved by the characterizing features of claim 1 solved in conjunction with its generic features.

The under claims form advantageous developments of the invention.

Of the The invention is based on the finding that the material properties of the cast node material has a significant impact on the failure time have the casting node in case of an accident.

To According to the invention, the subframe for a motor vehicle comprises a first and a second, respectively in the vehicle longitudinal direction aligned longitudinal beams and arranged between the two longitudinal beams, in the vehicle transverse direction aligned cross member. Between the first side member and the cross member is a first casting node and between the second side member and the cross member arranged a second casting node. The two side members and the cross member are each firmly connected to the corresponding associated casting nodes. According to the invention is on two casting nodes each have a bowl-shaped attachment element arranged, which fixed respectively with the associated casting node connected is. The attachment element is made of a material trained, whose ductility greater than the ductility of the cast node material. In a simple way is now a subframe for a motor vehicle available put, the higher crash requirements is fair, since now due to the cup-shaped attachment element the structural element casting node has a greater ductility and thereby, in the event of an accident, a softer conversion of crash energy allows is. Even if the casting material of the casting knots from a certain Time suddenly failed and so to speak "crumbled", the corresponding area is through the cup-shaped Supporting element supported and the bowl-shaped Attachment element can still kinetic energy in forming work convert.

default way consists of the shell-shaped trained attachment made of stainless steel. Of course, it is also conceivable the formation of the cup-shaped Attachment made of other materials with corresponding material characteristics.

In advantageously includes or encloses the cup-shaped attachment element the assigned casting node only partially. The only In some areas, the casting node is surrounded by the bowl-shaped attachment element has the effect of making this a simple structural design ensured the attachment element is.

Since, as tests and simulations have shown, in the event of a crash, the force impulse introduced into the casting nodes initially causes a "lateral turning away". causes the casting node, the cup-shaped attachment element is preferably arranged in the vehicle transverse direction, each outside of the respective casting node. This "external arrangement" considerably restricts the inclination of the casting node for "sideways turning away".

According to one embodiment The invention is the cup-shaped Attachment element bolted to the associated casting nodes. The Fixing the cup-shaped Attachment has by means of a screw to the casting node the effect that a simple fastening movement of the bowl-shaped attachment element is guaranteed to the associated casting node.

According to one another embodiment The invention is the cup-shaped Attachment element positively clamped with the associated casting node.

The Fixing the cup-shaped Attachment element with the associated casting nodes by means of a screw and clamp connection in the present case is not an exhaustive list, since the attachment according to the invention of the bowl-shaped attachment element with the associated casting nodes also on other configurations in a simple way to realize.

Preferably is the bowl-shaped Attachment designed as a sheet metal stamping. Training as a sheet metal stamping proves to be advantageous, as a result a fast and inexpensive production of the cup-shaped Guaranteed essay element is.

Of the For simplicity, the two side members and the cross member as Extruded profiles formed. The training as extruded profiles allows a simple and in turn cost-effective production of the support elements Along- and crossbeams.

Around meets the requirements for a low weight of the subframe to become, consist the two side members and the crossbeam made of a light metal, in particular aluminum or aluminum alloy, while the cast nodes made of a light metal casting material, in particular Cast aluminum, consist.

Preferably are the two side members and the crossbeam with the corresponding cast nodes each via a welded joint firmly connected. This has the effect of being a simple and inexpensive installation of the subframe is ensured.

Further Advantages, features and applications of the present Invention will become apparent from the following description in conjunction with the embodiment shown in the drawing.

The The invention will be described in the following with reference to the drawings embodiment described in more detail. In the description, in the claims and in the drawing those in the below List of reference symbols used terms and associated reference numerals used.

In the drawing mean:

1 A plan view of a subframe for a motor vehicle without shell-shaped attachment elements at the casting node;

2 a detailed view of a cast node of the subframe off 1 with an associated, not yet mounted bowl-shaped attachment element in a view obliquely from below, and

3 a sectional view of the cup-shaped attachment element in the mounted state on a casting node of the subframe 1 ,

The in 1 shown in a plan view and overall with the reference numeral 10 designated subframe for a motor vehicle has a U-shaped basic structure. The subframe 10 essentially comprises a first side member 12 and a second side member 14 as well as a crossbeam 16 , While the longer legs of the U-shaped basic structure of the subframe 10 namely the side members 12 . 14 are aligned in the vehicle longitudinal direction FL, is the cross member 16 perpendicular thereto, ie aligned in the vehicle transverse direction FQ. In the present case, there are the two side members 12 . 14 and the cross member 16 made of an aluminum alloy and are formed as extruded profiles.

Between the first side member 12 and the cross member 16 is a first casting node 18 and between the second side member 14 and the cross member 16 is a second casting node 20 arranged. The two casting nodes 18 . 20 in the present case consist of an aluminum casting material.

For easy installation of the subframe 10 to ensure are in the first and second casting nodes 18 . 20 Provided openings in which the corresponding ends of the side members 12 . 14 or the cross member 16 are pluggable. After the "plug connection" of the components, namely the first side member 12 and crossbeams 16 in first casting node 18 , as well as second side member 14 and crossbeams 16 in second casting node 20 , the components are welded together, so that a solid Ver bond between the side rails 12 . 14 the corresponding casting node 18 . 20 and the cross member is made.

The subframe shown here 10 is intended for installation in the region of the front axle of the motor vehicle and has in a known manner corresponding bearing receptacles for mounting on the motor vehicle and corresponding receiving devices for storage of various components of the motor vehicle. Since the bearing receivers as well as the receiving devices for the present invention are not essential, a further description is omitted for reasons of scarcity.

Experiments and simulations have shown that in the event of an accident, the subframe 10 Initially initiated force pulse, first, a "lateral turning away", ie viewed in the vehicle transverse direction FQ, each directed outward movement of the two casting nodes 18 and 20 occurs and then a sudden failure of the two casting nodes 18 . 20 can be observed. Due to the predominant low ductility of the cast aluminum material of the cast nodes 18 . 20 this is literally "crumbled" under the influence of the force impulse.

The danger of sudden failure of the cast nodes 18 . 20 is significantly reduced by the present invention.

2 shows the second casting node 20 with an associated bowl-shaped attachment element 22 , A correspondingly designed attachment element is also the first casting node, not shown here 18 assigned.

The bowl-shaped attachment element 22 is with the cast node 20 firmly connected. The material of the attachment element 22 has a ductility which is greater than the ductility of the cast aluminum material of the cast nodes. In the present case is essay element 22 designed as a sheet metal stamping made of stainless steel.

Like next 2 can be seen, has the cup-shaped attachment element 22 corresponding holes on which the attachment element 22 via a screw connection with the casting node 20 and the second longitudinal members 14 and the cross member 16 firmly connectable.

3 shows in a sectional view of the bowl-shaped attachment element 22 the arrangement of the bowl-shaped attachment element 22 in relation to the casting node 18 in the assembled state. Out 3 is particularly apparent that the cup-shaped attachment element 22 the corresponding casting node 18 only partially includes or encloses. Moreover, it is off 3 the outer arrangement of the bowl-shaped attachment element with respect to the vehicle transverse direction FQ 22 clearly visible.

The effect of the bowl-shaped attachment element according to the invention is as follows: on the basis of the now at the two casting nodes 18 . 20 firmly arranged, made of stainless steel, cup-shaped attachment element 22 The "construction element casting node" or the area around the casting node has a significantly higher ductility or toughness. This ensures that, in the event of an accident, that next to the casting nodes 18 . 20 also the bowl-shaped attachment element 22 absorbs the resulting crash energy, ie the casting nodes 18 . 20 acting forces are minimized. Even if at some point on the casting nodes 18 . 20 acting forces should become too large and a failure of the casting knots 18 . 20 lead, then the corresponding area through the cup-shaped attachment element 22 further supported and the cup-shaped attachment element 22 can continue to convert kinetic energy into forming work. In addition, since the bowl-shaped attachment element 22 in the vehicle transverse direction FQ considered in each case outside of the respective casting node 18 . 20 are arranged, also a lateral turning away of the casting node 18 . 20 in the event of an accident.

10

subframe

12

first longitudinal beams

14

second longitudinal beams

16

crossbeam

18

first cast nodes

20

second cast nodes

22

cup-shaped attachment element

FL

Vehicle longitudinal direction

FQ

Vehicle transverse direction

Claims (11)

Subframe ( 10 ) for a motor vehicle, comprising a first and a second, respectively in the vehicle longitudinal direction (FL) aligned longitudinal members ( 12 . 14 ), one between the two side members ( 12 . 14 ), aligned in the vehicle transverse direction (FQ) cross member ( 16 ), and a first and a second casting node ( 18 . 20 ), wherein the first casting node ( 18 ) between the first side member ( 12 ) and the cross member ( 16 ) and the second casting node ( 20 ) between the second longitudinal member ( 14 ) and the cross member ( 16 ) is arranged and the two side members ( 12 . 14 ) and the cross member ( 16 ) with the corresponding casting nodes ( 18 . 20 ) are firmly connected, characterized gekennzeich net , that at both casting nodes ( 18 . 20 ) each have a cup-shaped attachment element ( 22 ) arranged with the associated casting node ( 18 . 20 ) is firmly connected, wherein the attachment element ( 22 ) is formed of a material whose ductility is greater than the ductility of the cast node material. Subframe according to claim 1, characterized in that the cup-shaped attachment element ( 22 ) is made of stainless steel. Subframe according to claims 1 and 2, characterized in that the cup-shaped attachment element ( 22 ) the associated casting node ( 18 . 20 ) only in certain areas. Subframe according to claims 1 to 3, characterized in that the cup-shaped attachment element ( 22 ) in the vehicle transverse direction (FQ) viewed in each case outside of the casting node ( 18 . 20 ) is arranged. Subframe according to claims 1 to 4, characterized in that the cup-shaped attachment element ( 22 ) with the associated casting node ( 18 . 20 ) is screwed. Subframe according to claims 1 to 4, characterized in that the cup-shaped attachment element ( 22 ) with the associated casting node ( 18 . 20 ) is positively clamped. Subframe according to one of the preceding claims, characterized in that the cup-shaped attachment element ( 22 ) is formed as a sheet metal stamping. Subframe according to one of the preceding claims, characterized in that the two longitudinal members ( 12 . 14 ) and the cross member ( 16 ) are formed as extruded profiles. Subframe according to one of the preceding claims, characterized in that the two longitudinal members ( 12 . 14 ) and the cross member ( 16 ) consist of a light metal, in particular aluminum or aluminum alloy. Subframe according to one of the preceding claims, characterized in that the casting nodes ( 18 . 20 ) consist of a light metal casting material, in particular aluminum casting. Subframe according to one of the preceding claims, characterized in that the two longitudinal members ( 12 . 14 ) and the cross member ( 16 ) with the corresponding casting nodes ( 18 . 20 ) are firmly connected by means of a welded joint.