Patent Application
20130264135
The present invention relates to supports for battery cells on motor vehicles and, more particularly, to preventing battery damage during rear impact using an optimized bracket separation structure.
Various automotive support structures for battery cells of motor vehicles have been proposed. For example, U.S. Pat. No. 8,037,960 discloses a battery pack fixed to an upper side of a mount by bolts. The battery pack includes screw holes through which the bolts are inserted. The screw holes have closed shapes and are elongate in a front-rear direction, so that the battery pack moves when an impact is applied to the battery pack. In another example, U.S. Pat. No. 7,921,951 discloses a forward portion of a battery pack is fixed to an upper surface of a cross member by forward brackets welded to a forward portion of the battery pack. A rearward portion of the battery pack is fixed to upper surfaces of a rearward portion of a kick-up portion of two side members by a bridge interconnecting the two side members. The battery pack is turned upward as the forward portion of the kick-up portion deforms and the bridge is pushed upward.
While the known battery cell support structures appear suitable for their intended purpose, it would be desirable to provide a battery cell support structure capable of preventing damage to a battery during rear impacts. It would be desirable to provide a battery support bracket with a controlled separation sequence to prevent battery cell damage located in a crush zone of the vehicle. It would be desirable to provide a controlled separation and deformation mode between the vehicle cross member and the battery attachment bracket during vehicle crush using a notch cut-out allowing the bracket to separate from the vehicle structure before deformation pulls the attachment bracket into contact with the battery body. It would be desirable to provide a deformation limiting gusset to prevent forward deformation of the bracket, where the battery support structure acts as a reaction surface.
In a support structure for protecting a battery of a motor vehicle from damage during a rear impact, a battery attachment bracket connects the battery to support structure of the motor vehicle in an area subject to deformation during a rear impact. The battery attachment bracket can include a body member extending from a battery-engaging surface to a vehicle-support-engaging surface. The vehicle-support-engaging surface can include a bolt-receiving aperture formed therein and a notch cut-out formed adjacent to the bolt-receiving aperture to define a narrowed portion of the battery attachment bracket located in a vehicle-front direction with respect to the bolt-receiving aperture.
A method is provided for assembling the battery attachment bracket. The battery attachment bracket is a welded assembly of a first member, a second member and a third member. The first member defines a vehicle-rear-facing surface and includes the vehicle-support-engaging surface and a portion of the battery-engaging surface. The vehicle-support-engaging surface includes a bolt-receiving aperture and a notch cut-out located in a vehicle-front direction from the bolt-receiving aperture. The second member defines a vehicle-front-facing surface and includes two side surfaces for assembly with respect to the first member. The second member also includes a portion of the battery-engaging surface. The third member defines a gusset having an angled surface with a narrow end adjacent the vehicle-support-engaging surface and an enlarged end adjacent the battery-engaging surface. The third member is assembled with respect to the vehicle-front-facing surface of the second member.
Other applications of the present invention will become apparent to those skilled in the art when the following description of the best mode contemplated for practicing the invention is read in conjunction with the accompanying drawings.
The description herein makes reference to the accompanying drawings wherein like reference numerals refer to like parts throughout the several views, and wherein:
Referring now to
If the battery 14 is placed in the deformation path of the battery attachment bracket 10, battery damage can occur during rear impact events. If the separation of the attachment bracket 10 requires too much force, the attachment bracket 10 may deform into the battery 14. In addition to the bolt separation event, later during the crash further deformation can allow a rear suspension structure 12a to contact the bracket 10. A gusset 16 located on the bracket 10 can resist a push from a rear suspension structure 12a by having a strong compressive resistance to a touch-off point on the battery-supporting structure 14a. The gusset 16 transfers rear impact load from the battery attachment bracket 10 to the battery-supporting structure 14a.
The attachment bracket 10 allows for a decreased separation load under crash conditions, but maintains fastening reliability requirements for typical use by maintaining a full contact area 18 between a fastening member, such as a bolt head and/or washer 20a and the attachment bracket 10. This allows for maximum usage of space for placing batteries 14 in an area that would otherwise be impacted by a deforming attachment bracket 10, allowing for increased vehicle range.
By way of example and not limitation, during a rear impact event, the rear vehicle structure 12, 12a translates forward and then buckles in an overall upward direction. During the initial forward motion of the vehicle support structure 12, the attachment between the vehicle support structure 12 and the battery 14 is loaded in a way the pulls the attachment bracket 10 of the battery 14 forward, in a direction toward the battery 14. By reducing the cross-sectional area of the material adjacent a top bolt aperture 10a of the attachment bracket 10, the top bolt 20 can tear through the bracket 10 and release before the attachment bracket 10 deforms into the battery 14. A notch cut-out 10b allows the attachment bracket 10 to separate from the vehicle support structure 12 before the deformation of the vehicle support structure 12 pulls the attachment bracket 10 into contact with the main body of the battery 14.
Referring now to
The notch cut-out 22d of the battery attachment bracket 10 is of sufficient size to allow the support structure 12 of the motor vehicle to separate from the battery attachment bracket 10 when a predetermined force is applied during a rear impact. The predetermined force is of a sufficient magnitude to be capable of driving a bolt 20 which extends through the bolt-receiving aperture 22c for holding the battery attachment bracket 10 to the support structure 12 of the motor vehicle tearing through the narrowed portion 22e of the battery attachment bracket 10 defined by the notch cut-out 22d. The notch cut-out 22d of the battery attachment bracket 10 is located completely external to a clamping surface area 18 defined with respect to a periphery of a fastening member, such as a bolt head and/or washer 20a of a bolt 20 to be received within the bolt-receiving aperture 22c of the battery attachment bracket 10. This configuration allows maximum clamping load of the fastening member, such as a bolt head and/or washer 20a through the full contact area 18. In other words, the clamping load is not reduced by a smaller contact area which would result from the notch cut-out 22d encroaching within the periphery of the fastening member, such as a bolt head and/or washer 20a.
A gusset 16 is located on a vehicle-front-facing surface 22f of the bracket 10. The gusset 16 can have an angled surface 16a extending from a narrow end 16b adjacent the vehicle-support-engaging surface 22b to an enlarged end 16c adjacent the battery-engaging surface 22a. The enlarged end 16c of the gusset 16 engages with a battery-supporting structure 14a in response to deformation of the battery attachment bracket 10 during a rear impact of sufficient force to drive the support structure 12 of the motor vehicle in a vehicle-front direction. The enlarged end 16c of the gusset 16 resists further deformation of the battery attachment bracket 10 and promotes separation of the battery attachment bracket 10 from the support structure 12 of the motor vehicle adjacent the bolt-receiving aperture 22c. The gusset 16 transfers crushing rear impact load from other vehicle structure 12a contacting the battery attachment bracket 10 after release from the support structure 12 of the motor vehicle to the battery-supporting structure 14a thereby protecting the battery 14 from damage.
As best seen in
A method for assembly a battery attachment bracket 10 is disclosed. The method can include forming a body member 22 with a vehicle-support-engaging surface 22b, forming a bolt-receiving aperture 22c in the vehicle-support-engaging surface 22b, and forming a notch cut-out 22d in the vehicle-support-engaging surface 22b in a vehicle-front direction with respect to the bolt-receiving aperture 22c to define a narrowed portion 22e of the battery attachment bracket 10 to facilitate separation of the battery attachment bracket 10 from a support structure 12 of the motor vehicle during rear impact deformation. A gusset 16 can be provided on a battery-facing surface 22f of the battery attachment bracket 10 to resist deformation of the battery attachment bracket 10 into the battery 14 prior to separation of the battery attachment bracket 10 from the support structure 12 of the motor vehicle and to transfer rear impact load from the battery attachment bracket 10 to a battery-supporting structure 14a during and after separation of the battery attachment bracket 10 from the support structure 12 of the motor vehicle.
The body member forming method can include forming a first member 26 with a vehicle-support-engaging surface 22b and a portion 26a of a battery-support-engaging surface 22a, and forming a second member 28 with a battery-facing surface 28a, two side walls 28b, 28c for attachment to the first member 26, and a portion 28d of a battery-support-engaging surface 22a. The method can include forming a third member 30 with the gusset 16 for attachment to the battery-facing surface 28a of the second member 28. The process can include forming the gusset 16 with an angled surface 16a having a narrowed end 16b adjacent the vehicle-support-engaging surface 22b and an enlarged end 16c adjacent the battery-support-engaging surface 22a. The process can form the battery attachment bracket 10 as an assembly 24 of the first, second, and third members 26, 28, 30 welded together along weld lines 32 into a single unitary body member 22.
As best seen in
While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiments but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims, which scope is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures as is permitted under the law.
