Back Door Structure with Four-Bar Linkage and Supporting Member
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Solution Overview
Problem
Existing back door opening/closing devices require significant operation force due to the varying direction of biasing force needed to reduce the projection amount of the back door when opening, which may not be adequately addressed by the damper stay alone.
Innovation Solution
A back door structure incorporating a four-bar linkage mechanism with a supporting member that biases the second arm toward the vehicle upper side, combined with a damper stay to reduce the operation force, and a projection on the second arm to enhance the biasing force through leverage, ensuring the back door opens with reduced effort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the center of swing of the back door shifts toward the vehicle front as the back door opens, then the projection amount of the door toward the vehicle rear is reduced, but the operation force to open the back door increases
Solution Approach 1:
The supporting member acts as a counterweight mechanism by biasing the second arm toward the vehicle upper side, generating a force that counteracts the increased operation force required by the shifted swing center. This allows the back door to open smoothly despite the changed rotation path.
Solution Approach 2:
The supporting member serves as an intermediary element between the second arm and the back door, transmitting and adjusting forces to balance the system. It mediates the force distribution to ensure easy opening while maintaining the reduced projection amount.
2Device complexity
If only a damper stay is used to bias the back door in the opening direction, then the structure is simple, but the operation force is not sufficiently reduced
Solution Approach 1:
The force assistance system is segmented into two independent components: the damper stay for basic biasing and the supporting member for additional force reduction. This segmentation allows each component to perform its function optimally while keeping the overall structure manageable.
Solution Approach 2:
The damper stay and supporting member are combined to work together in reducing operation force. The supporting member complements the damper stay by providing biasing force in a different direction (toward vehicle upper side), creating a synergistic effect that significantly reduces operation force.
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
The combination of the four-bar linkage and supporting member reduces the operation force required to open the back door, minimizing its projection onto the vehicle rear and preventing interference between components, while the projection enhances the biasing force for further reduced operation effort.
Implementation Method 1
The damper stay is biased so as to elongate along its length direction, thereby biasing the back door in an opening direction
Implementation Method 2
The supporting member biases the other end portion of the second arm substantially toward a vehicle upper side
Implementation Method 3
The first arm and the second arm act as a four-bar linkage, so to speak, such that the back door swings about an imaginary point (instant center of rotation) due to restriction by this linkage
Data Source
AI summary
A back door structure includes a first arm, a second arm, a damper stay, and a supporting member. The first arm is fixed to an upper section of a vehicle body rear section, and is fixed to an upper section of a back door. The second arm is fixed to the upper section of the vehicle body rear section, and is fixed to the upper section of the back door. The damper stay is fixed to the back door, is fixed to the vehicle body rear section, and biases the back door in an opening direction. The supporting member is fixed to the second arm, is fixed to the back door, and biases the second arm substantially toward a vehicle upper side in a fully closed state of the back door.