Avoiding structural redundancies between the vehicle body and the battery housing based on a functional integration approach

Abstract

In this paper, the approach for a functionally integrated battery housing is presented, to avoid structural redundancies towards the vehicle body. The goal is to reduce the overall structural weight while simultaneously increasing the package space for battery modules. The typically existing boundary conditions for the battery system are taken into account. Especially, the detachability of the battery as a closed unit is in focus, to ensure the leak tightness of this system and to enable replacement. Based on the available space in a research vehicle, such a functionally integrated concept is developed. In particular, the vehicle floor and the vehicle rocker are identified as suitable components for integration. The verification of the concept with regard to the crash performance is carried out on component and on full vehicle level. On both levels, the side pole impact is used as load case and the deformation behavior is investigated.

Parametric Analysis of a Divided Rocker for Battery Electric Vehicles

“…Several studies have explored the potential of optimized battery placement inside the vehicle structure, such as incorporating a battery housing with thermal functions [16], battery housing modification for reducing mass [17], and battery system packing efficiency analysis [15]. This paper is based on an existing study for a functionally integrated battery housing, in which a divided rocker concept was developed to reduce the structural redundancies between the vehicle body and the battery housing [18], [19]. In accordance with this study, as a requirement, the battery housing should be able to attach and detach from the vehicle body during assembly/disassembly and repairs.…”

“…Moreover, since several safety tests are typically performed on the battery on a system level [9], [10], [11], it is beneficial to keep the structures of the battery housing as a separate system. Following the approach of [18], [19], for a space-efficient integration, the battery side frame is designed to be a part of the vehicle rocker. The concept divides the vehicle rocker into two parts while maintaining the outer dimensions of the vehicle rocker from the reference vehicle taken from the EU-funded project ALIVE [20].…”

“…In accordance with [19], the vehicle rocker is divided by means of a division plane and the upper part of the rocker is attached to the seat cross-members while the lower part is integrated into the side frame structure of the battery housing. A general division plane is shown in Figure 1.…”

“…Additionally, these two-division planes are rather easy to manufacture. Furthermore, the vertical surface supports the positioning of the battery and therefore, can be advantageous in a side crash scenario [19].…”

“…The crash test parameters are set up according to Euro NCAP side pole crash test [22]. The general setup on a component level is similar to the setup described in [18], [19]. The length, width and height of the divided rocker are similar to that of the reference vehicle rocker [20].…”