Vehicle Subframe Structure With Short Rigid Vibration Path
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Solution Overview
Problem
Conventional subframe structures face challenges in effectively reducing power train vibration while maintaining impact absorption and mount support functions, particularly when the length of the vibration transmitting path is extended and damping members are used, leading to suboptimal damping performance.
Innovation Solution
The subframe structure incorporates a reinforcement part, such as a rib, connecting the vehicle body attaching part and the accommodating part, with a cross member extending inward to couple the body part, and the mount support part is fixed to both the body part and the cross member, creating a shorter vibration transmitting path that demonstrates a vibration characteristic close to a rigid body, thereby enhancing damping performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the length of the vibration transmitting path is extended and damping members are added, then the vibration attenuation is improved, but the damping performance becomes suboptimal
Solution Approach 1:
The patent removes the accommodating part and other attenuating elements from the vibration transmitting path between the mount support part and the vehicle body. By extracting these components that cause suboptimal damping, the vibration path becomes direct and rigid, allowing the PT mount to demonstrate its intended damping performance effectively.
Solution Approach 2:
Instead of extending the vibration path and adding damping members to attenuate vibration, the patent inverts the approach by shortening the path and making it rigid. The vibration attenuation is achieved not through path extension with dampers, but through direct rigid connection that eliminates suboptimal damping elements.
2Weight of moving object
If the subframe structure is constructed without tower members to reduce weight and component number, then the vehicle weight and component number are reduced, but the load path for transmitting impact load to the frontside frame is not formed
Solution Approach 1:
The subframe body part is designed to perform multiple functions simultaneously: it supports the power train through the mount support part, transmits impact loads from the extension frame to the frontside frame, and provides structural rigidity. This multi-functionality eliminates the need for separate tower members while maintaining both weight reduction and load path formation.
Solution Approach 2:
The patent merges the functions of the subframe and tower members into a single integrated subframe structure. The body part of the subframe directly connects the mount support part to the frontside frame attachment, combining what were previously separate components into one unified structure that achieves both weight reduction and adequate load transmission.
3Device complexity
If the subframe independently bears the forward impact absorbing function, then the tower members are eliminated, but the burden on the subframe increases making it difficult to achieve both mount support and impact absorption functions
Solution Approach 1:
The subframe is segmented into functional zones: the body part handles impact load transmission to the frontside frame, while the mount support part independently supports the power train. This segmentation allows each zone to specialize in its function, enabling the subframe to bear both functions simultaneously without excessive burden on a single structure.
Solution Approach 2:
Different parts of the subframe have different structural qualities optimized for their specific functions. The body part is designed with higher rigidity for impact load transmission, while the mount support part has appropriate compliance for power train support. This local quality differentiation enables the subframe to perform multiple functions effectively.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration effectively reduces power train vibration by optimizing the spring constant of the mount rubber and eliminating attenuating elements, increasing the support rigidity of the PT mount and the subframe, and reducing the weight and size of the structure.
Implementation Method 1
a measure to attenuate the vibration described above is also adopted to a path from a mount support part to the vehicle body via the subframe
Implementation Method 2
adding a damping member, such as a rubber bush, between the subframe and the vehicle body
Data Source
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AI summary
A subframe structure includes a subframe (710) disposed below a vehicle body structure (620) of a vehicle, and an extension frame (730) extending forward from the subframe (710) and configured to absorb an impact load from forward of a vehicle body. The subframe (710) has a body part (711) extending in a vehicle front-and-rear direction and a mount support part (690) supporting a power train (604) through a mount. The body part (711) is fixed to the vehicle body structure (620) through the mount support part (690).