Vehicle Subframe Stiffening via Steering Gear Housing Integration
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Solution Overview
Problem
Existing subframes for motor vehicles face challenges in achieving a lightweight yet rigid construction that allows for favorable assembly and installation of rack-and-pinion steering gear, with existing designs often requiring complex cross members and limited design freedom.
Innovation Solution
A U-shaped subframe with detachable longitudinal members and a cross member, reinforced by a stiffening element and steering gear housing, which allows for flexible component arrangement and assembly, with the steering gear housing being either connected to the cross member or side members, providing enhanced rigidity and ease of assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a traditional cross member is positioned high to cover the steering gear housing, then the steering gear can be easily accessed for assembly, but the subframe requires additional structural complexity and weight
Solution Approach 1:
The cross member is repositioned from a high position (covering the steering gear from the front) to a low position (underneath the steering gear housing). This spatial reconfiguration in the vertical dimension allows the steering gear to be accessed from above while the cross member remains structurally functional, eliminating the need for the cross member to cover the steering gear.
Solution Approach 2:
The connection between the cross member and longitudinal members is made detachable rather than integral. This segmentation allows independent optimization of each component's position and function, enabling the cross member to be positioned low underneath while maintaining structural integrity through separate fastening connections.
2Adaptability or versatility
If the cross member is positioned low underneath the steering gear, then design freedom is increased, but the subframe rigidity is reduced
Solution Approach 1:
Stiffening elements are pre-integrated into the longitudinal members at the connection points with the cross member. This preliminary reinforcement ensures that when the cross member is positioned low, the structural rigidity is maintained through the pre-positioned stiffening features that prevent deformation at critical connection zones.
Solution Approach 2:
The longitudinal members incorporate composite construction with integrated stiffening elements, combining different structural features (such as internal ribs or reinforced sections) within the longitudinal members themselves to compensate for the reduced leverage effect of the low-positioned cross member.
3Strength
If the steering gear housing is clamped between the longitudinal members and cross member, then double-shear connection provides high rigidity, but the assembly requires precise positioning
Solution Approach 1:
Fastening brackets serve as intermediary components between the steering gear housing and the subframe structure. These brackets provide standardized connection interfaces with positioning features that guide precise alignment during assembly, reducing the direct positioning requirements between the cross member and longitudinal members.
Solution Approach 2:
The fastening brackets incorporate tolerance compensation features and positioning elements that absorb alignment variations during assembly. This beforehand cushioning of positioning errors allows the double-shear connection to achieve high rigidity without requiring extremely precise initial positioning of all components.
Data Source
Figure 1
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AI summary
The sub-frame (10) has U-arm lateral longitudinal supports (12, 14) and a U-base transverse support (16) that are provided on attachment points for suspension elements and/or a suspension mount. The longitudinal supports are detachably connected with the transverse support. The longitudinal- and/or transverse supports are reinforced with a steering gear housing (32), where the sub-frame is reinforced with a stiffening element (38) that is processed between the longitudinal supports and firmly connected with the transverse support.