Chassis arrangement for a motor vehicle

Abstract

A chassis assembly for a motor vehicle, comprising a chassis with a subframe (10) which is connected to a component (30) of the chassis or body via at least one fastening point (20), wherein the fastening point (20) is designed such that it releases along the Z-axis when a predetermined force is applied between the component (30) of the chassis or body and the subframe (10), and the chassis assembly is provided in the front region of the motor vehicle, while the subframe (10) is arranged below its at least one fastening point (20), characterized in that at least one forwardly downwardly inclined ramp (40) is formed in the front region of the subframe (10), which ramp can thus be contacted by a component (50) of the drive train of the motor vehicle, which component is to move in the X-direction onto the subframe (10) in the event of a frontal impact of the motor vehicle.that a force is thereby applied downwards along the Z-axis to the fastening point (20) between the subframe (10) and the component (30) of the chassis or the body, by means of which force the subframe (10) tears downwards from the fastening point (20).

Description

[0001] The invention relates to a chassis arrangement for a motor vehicle according to the preamble of claim 1. The invention further relates to a motor vehicle with such a chassis arrangement.

[0002] The generic DE 39 25 990 A1 discloses a downwardly inclined ramp on the rear of a subframe / chassis. This ramp, in conjunction with a corresponding slope on the vehicle floor, is intended to ensure that the subframe is deflected downward in the event of a frontal impact. The subframe thus moves toward the slope and slides down it. The subframe should not detach from its mountings.

[0003] DE 100 31 165 C2 discloses a positive guide for an engine and / or transmission unit, which also uses a ramp. The ramp is used to deflect the unit in a specific direction in the event of a frontal impact. This crash step is attached to the rear of the unit in the direction of travel and is tilted downwards. In a crash, the inclined surface of the crash step strikes a bearing support of a transmission mount and slides diagonally upwards off it. In the process, the bearing core of the transmission mount, which is supported on a cross member, tears off. However, the cross member itself does not tear off.

[0004] EP 1 510 444 B1 discloses a subframe with two ramps in its rear area. These two ramps are inclined downwards and serve to push the subframe under the passenger compartment in the event of a frontal impact. Although the subframe tears away from the body, this is not caused by the impact of a component on a ramp on the subframe, but rather by the subframe's rearward movement.

[0005] DE 10 2008 015 182 A1 discloses the deflection of a subframe beneath a passenger cell. The subframe is connected to a pivotally mounted strut that rests against the vehicle body. If the subframe moves toward the passenger cell during a frontal impact, it experiences a moment from the strut and is deflected downward. Before the subframe can move in this way, its fastening elements break off.

[0006] DE 10 2004 008 647 A1 discloses an engine mount with a sliding slope. A brake booster slides along this slope in the event of a crash.

[0007] Motor vehicles typically comprise chassis assemblies with at least a frame and an underbody supported by the frame. Vehicles with a self-supporting body also feature subframes or subframes that support various vehicle components. These include, in particular, drivetrain components and wheel suspensions. Such a subframe is attached, for example, to the underbody or side member of the vehicle, which can be achieved using bolted connections, welded joints, etc.

[0008] In the event of a frontal collision of a motor vehicle, for safety reasons the front structural components of the vehicle are designed to deform in order to absorb energy. The plastic deformation of body parts converts the kinetic energy into deformation energy. However, since subframes in modern motor vehicles are often very rigid, in particular to absorb lateral forces, the rigidity of the subframe can prevent the desired deformation of body parts. Therefore, it can be designed for subframes to detach from other body parts in the event of a frontal collision. In particular, subframes can be designed to detach from the underbody. For example, subframes can detach if the connection between the subframe and the underbody shears off. Separation due to twisting is also possible.

[0009] For example, US 2015 / 0 314 807 A1 discloses a chassis assembly for a vehicle with a subframe assembly, wherein this subframe assembly includes a frame, a subframe, and an underbody. The underbody is supported by the frame, and the subframe is connected to the underbody. A lever extends from the subframe to the frame, and this lever applies leverage against the frame when the subframe is rotated relative to the frame during a frontal impact. In this way, the connection between the subframe and the underbody can be released.

[0010] Furthermore, it is known to displace a detached subframe in a specific direction during a frontal impact. For example, US Pat. No. 7,229,099 B2 discloses a chassis-subframe assembly in which a subframe is attached to the body of a vehicle at four points. In a frontal impact, these attachment points detach, and the subframe is pushed under the underbody structure of the passenger compartment using a sheet metal ramp. This measure is intended to allow larger areas of the body to be used as deformation zones.

[0011] A corresponding solution for electric or hybrid vehicles is known from US 2013 / 0 270 861 A1, in which both drive batteries and high-voltage converters are to be protected in the event of a collision. Among other things, two sheet metal ramps are provided that direct the movement of a rear subframe under the battery in the event of a collision. This is intended to prevent damage to the battery caused by the subframe.

[0012] US 9 216 768 B1 also describes a subframe assembly with multiple ramps intended to divert the movement of a drivetrain in the event of an impact away from a fuel tank, fuel line, brake line, or similar components in order to protect these components from damage. Other types of frame structures may also include one or more ramps. For example, EP 2 985 208 A1 discloses a front structure of a vehicle in which a first ramp is formed by arranging a front region of a frame higher than a rear region. A suspension element is located in front of this ramp and also has sloped walls.

[0013] US 9 352 785 B2, on the other hand, discloses a subframe for a motor vehicle, wherein the subframe folds downwards in the event of an impact of the vehicle.

[0014] In this case, the front attachment points, which connect the subframe to a crash rail, come loose, while the rear attachment points, which connect the subframe to the body, do not come loose.

[0015] In order to separate a subframe from a vehicle component, a certain force in the vertical direction, i.e. in the Z direction, is often required. However, depending on the kinematics of the drivetrain of a particular vehicle, the forces occurring in a frontal impact can fluctuate between a force in the X direction (longitudinal direction of the vehicle) and a force with force components in the X and Z directions. If the force component in the X direction is large and the force components in the Z direction are too small, the separation of the subframe from the underbody can be delayed or even not occur at all. This leads to the vehicle structure / securing structure being overloaded because the non-detached subframe forms an additional boundary condition for the longitudinal members and restricts the deformation degrees of freedom of the longitudinal member.

[0016] In view of the state of the art shown, there is still room for improvement in the area of ​​subframe separation in the event of a frontal collision of a motor vehicle.

[0017] The invention is based on the object of providing a chassis arrangement for a motor vehicle in which a subframe is released early and reliably, in particular even when pure forces act on the subframe in the X-direction.

[0018] According to the invention, the object is achieved by a chassis arrangement having the features of claim 1 and by a motor vehicle having the features of claim 7.

[0019] A chassis arrangement for a motor vehicle is shown, comprising a chassis with a subframe which is connected to a component of the chassis or the body via at least one fastening point, wherein the fastening point is designed such that it releases when a predetermined force between the component of the chassis or the body and the subframe along the Z-axis, and the chassis arrangement is provided in the front region of the motor vehicle, while the subframe is arranged below its at least one fastening point.According to the invention, at least one ramp inclined downwards towards the front is formed in the front region of the subframe, which ramp can be contacted by a component of the drive train of the motor vehicle which is to move in the X direction onto the subframe in the event of a frontal impact of the motor vehicle, such that a force is applied downwards along the Z axis to the fastening point between the subframe and the component of the chassis or the body, as a result of which force the subframe tears downwards away from the fastening point.

[0020] Further, particularly advantageous embodiments of the invention are disclosed in the dependent subclaims.

[0021] It should be noted that the features and measures listed individually in the following description can be combined with one another in any technically reasonable manner within the scope of the claims and demonstrate further embodiments of the invention. The description further characterizes and specifies the invention, particularly in conjunction with the figures.

[0022] The chassis arrangement according to the invention for a motor vehicle has a chassis with a subframe which is connected to a component of the chassis or the body via at least one fastening point. The fastening point is designed such that it detaches when a predetermined force is applied between the component of the chassis or the body and the subframe along the Z-axis. Due to forces during an impact of the motor vehicle with another object, in which a force component in the Z direction acts on the at least one fastening point, the subframe can thus be detached from a component if this force exceeds a predetermined level. If the subframe is attached to a component of the body, as is the case with an underbody attachment, for example, it detaches from a component of the body.However, if the subframe is attached to a component of the chassis, as is the case when attached to a side member, for example, it will detach from a component of the chassis.

[0023] The Z-axis runs vertically through the vehicle or chassis assembly. The X-axis, on the other hand, runs longitudinally through the vehicle. For the purposes of this invention, a force in the Z-direction or X-direction means that a force runs along the respective axes; however, the direction of the force—up / down and front / back—is not determined by this. A force in the Z-direction can therefore be directed both vertically upwards and downwards.

[0024] As already mentioned above, at least one inclined ramp is formed in the front region of the subframe, which can be contacted by a component of the motor vehicle that is to move in the event of an impact of the motor vehicle against the subframe, such that a force along the Z axis, i.e. in the Z direction, is applied to the attachment point between the subframe and the component of the chassis or body. If this force component in the Z direction is sufficiently large in the event of an impact of the vehicle, the subframe detaches from the component of the chassis / body to which it is attached. In this way, the deformation behavior of the motor vehicle can be improved in the event of an impact.

[0025] In particular, this chassis design makes it possible to utilize movements of vehicle components that only move in the X direction toward a subframe to release the subframe. Even if a component hits the subframe purely in the X direction, this movement can be converted by the at least one ramp on the subframe into a sufficiently large force component in the Z direction, causing the subframe to release.

[0026] The component contacting the ramp can be various components of the vehicle. In one embodiment, this is a component of the drivetrain, in particular a transmission housing. The ramp of the subframe thus interacts with a part of the drivetrain, and in particular, a pure force component of the drivetrain in the X direction can be converted into a large Z force. This makes it possible, in particular, to achieve robust detachment of the subframe with relatively small engines, which behave kinematically differently than larger engines. This increases occupant safety and can be advantageously used as part of future improved safety strategies for motor vehicles.

[0027] The subframe can be detached from various components of the motor vehicle. In particular, this can be an underbody and / or a longitudinal member. Preferably, the chassis assembly is located in the front area of ​​the motor vehicle, so that the subframe is a front subframe.

[0028] As already mentioned above, the ramp is inclined downwards towards the front, and the force is directed downwards in the Z-direction. If a drivetrain component hits this ramp from the front, the ramp and thus the subframe are pushed downwards in this area, causing the subframe to detach from a vehicle component due to a tensile force in the Z-direction. In such an embodiment, the subframe is arranged below its attachment point and tears downwards from it.

[0029] However, ramps with different gradients could also be provided, which move the subframe toward its attachment point and push it through a sheet metal, for example. Thus, with a corresponding design of the entire chassis arrangement, a ramp could also be inclined upwards toward the front, and the force in the Z direction would then be directed upwards.

[0030] The ramp is inclined, for example, at an angle of between 10° and 45° to the horizontal. One or more ramps can be provided, and one ramp can be integrated into the structure of the subframe. In an alternative embodiment, the ramp can be formed by a separate element attached to the subframe. This can, in particular, be an obliquely mounted sheet metal or a wedge-shaped element. The contact surface of the ramp can simultaneously be rotated or curved around its longitudinal axis in order to accommodate individual drivetrain variables and kinematics (rotations around the x / y / z axis) in a frontal impact.

[0031] The ramp can be welded, glued, and / or bolted to the subframe. An auxiliary structure between the subframe and ramp is also conceivable to bridge gaps between the ramp and subframe if necessary. This auxiliary structure can, if necessary, transfer loads into the subframe over a larger area and thus distribute them. A ramp can also be retrofitted to a subframe. The required position of the ramp can be specifically selected. If a combination of subframe and drivetrain does not allow for reliable detachment of the subframe in the event of a vehicle impact, robust detachment can also be achieved in this way on such a vehicle.

[0032] Depending on the load levels encountered, the material of the ramp and auxiliary structure can vary. High-strength steels are conceivable, but lightweight materials (aluminum, magnesium) or appropriately shaped nylon blocks are also possible. If necessary, specifically heat-resistant materials can be used.

[0033] The invention also encompasses a motor vehicle having a chassis arrangement according to one of the described embodiments. Such a motor vehicle can meet high safety requirements, since its chassis arrangement ensures robust detachment of the subframe in the event of a frontal impact.

[0034] Further advantageous embodiments of the invention are disclosed in the dependent claims and the following description of the figures. Fig. 1 a schematic side view of a chassis arrangement with a subframe without a ramp according to the invention, Fig. 2 a schematic side view of an embodiment of a chassis arrangement according to the invention with a subframe with a ramp according to the invention, and Fig. 3 a three-dimensional view of a chassis arrangement according to Fig. 2.

[0035] In the different figures, identical parts are always provided with the same reference symbols, which is why they are usually only described once.

[0036] The Fig. 1 is preferably located in the front area of ​​a vehicle (not shown), the front of the vehicle being in the Fig. 1 is on the right. The X-direction runs in the longitudinal direction of the vehicle, while the Z-direction runs vertically through the vehicle. The chassis assembly has a subframe 11, which is fastened to a component of the vehicle. This component is a longitudinal member 30 of the vehicle. The subframe 11 is connected to this longitudinal member 30 via at least one fastening point (not shown in detail). The area of ​​this fastening point is in the Fig. 1 is marked with a dashed circle and the reference number 20. The subframe 11 is located below this fastening point 20. Preferably, several such fastening points are provided, wherein the subframe 11 could also be connected to various other components of the vehicle in addition to the longitudinal member 30.

[0037] The fastening points 20 are each detachable if a sufficiently large force acts on the fastening point in the Z direction. This detachability can be achieved by means known per se, which are familiar to those skilled in the art. Both detachable and non-detachable fastening points can also be provided.

[0038] Located in the area of ​​the chassis assembly is a drivetrain component, namely a transmission housing 50. This transmission housing 50 is located relatively close to the front edge of the subframe 11, but does not touch it during normal operation of the vehicle. The subframe 11 of the Fig. 1 does not have a ramp according to the invention. If, during a frontal impact of the vehicle, the drive train moves in the X direction toward the subframe, the resulting force component 60 in the X direction may not be sufficient to release the subframe 11 at its attachment point 20.

[0039] A chassis arrangement according to the invention therefore has a ramp for converting the forces on such an otherwise unchanged subframe. A side view of an embodiment of such a chassis arrangement is shown schematically in Fig. 2 shown. Fig. Figure 3 shows the solution according to the invention in a three-dimensional view. The structure of the chassis assembly essentially corresponds to that shown in Figure Fig.1. However, the inventive embodiment of a subframe is designated by reference numeral 10 and has a ramp 40 in its front region. This ramp 40 is inclined downwards in the X direction and is formed by a structure that can be shaped in various ways. For example, it can be a sheet metal that is attached at an angle to the front side of the subframe 10. The ramp 40 extends at an angle α between 10° and 45° to the horizontal.

[0040] If a drivetrain component, such as the transmission housing 50, moves toward the subframe 10 in the X direction during a frontal impact, it strikes the ramp 40, converting the force of the movement into a force component 60 in the X direction and a force component 70 in the Z direction. In this case, the transmission housing, for example, strikes the ramp 40 with a projection 51. The force component 70 thus generated in the Z direction pushes the front side of the subframe 10 downward, causing it to detach from the longitudinal member 30 at its attachment point. List of reference symbols: 10 subframes with ramp 11 Subframe without ramp 20 attachment point 30 component, longitudinal member 40 Ramp 50 gearbox housing 51 lead 60 Force component X-direction 70 Force component Z-direction

Claims

[1] Chassis arrangement for a motor vehicle, comprising a chassis with a subframe (10) which is connected to a component (30) of the chassis or the body via at least one fastening point (20), wherein the fastening point (20) is designed such that it releases when a predetermined force is applied between the component (30) of the chassis or the body and the subframe (10) along the Z-axis, and the chassis arrangement is provided in the front region of the motor vehicle, while the subframe (10) is arranged below its at least one fastening point (20), characterized byin that at least one ramp (40) inclined downwards towards the front is formed in the front region of the subframe (10), which ramp can be contacted by a component (50) of the drive train of the motor vehicle, which component is to move in the X direction onto the subframe (10) in the event of a frontal impact of the motor vehicle, in such a way that a force is applied downwards along the Z axis to the fastening point (20) between the subframe (10) and the component (30) of the chassis or the body, as a result of which force the subframe (10) tears downwards away from the fastening point (20). [2] Chassis arrangement according to claim 1, characterized by that the ramp (40) is inclined at an angle of between 10° and 45° to the horizontal. [3] Chassis arrangement according to claim 1 or 2, characterized by that the ramp (40) is integrated into the structure of the subframe (10). [4] Chassis arrangement according to claim 1 or 2, characterized bythat the ramp (40) is formed by a separate element which is attached to the subframe (10). [5] Chassis arrangement according to claim 4, characterized by that the ramp (40) is welded, glued and / or screwed to the subframe (10). [6] Chassis arrangement according to one of claims 1 to 5, characterized by that the part of the drive train which contacts the ramp (40) is a gearbox housing (50). [7] Motor vehicle comprising a chassis arrangement according to one of the preceding claims.

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