Seat Return Interlock Assembly for Easy-Entry Position Control
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Solution Overview
Problem
Seat cushions in typical automotive vehicle seat assemblies often prematurely shift from the easy entry position to the design position before reaching an intermediate position, causing inaccuracies in seat movement along the vehicle floor.
Innovation Solution
A seat assembly with a four-bar linkage assembly and an interlock mechanism that selectively locks and unlocks the seat cushion, allowing precise control over its movement between easy entry and design positions, utilizing a linkage locking and release mechanism and a track locking and release mechanism for controlled sliding and tilting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a typical seat assembly uses a four-bar linkage assembly for movement between easy entry position and design position, then the seat cushion can tilt forwardly and downwardly toward the floor, but the seat cushion erroneously and prematurely shifts from the easy entry position to the design position prior to reaching an intermediate position
Solution Approach 1:
An interlock element is introduced as an intermediary component between the four-bar linkage assembly and the seat cushion. This interlock element includes an interlock hook that engages with a striker pin on the front link, preventing the seat cushion from prematurely shifting from the easy entry position to the design position. The interlock element acts as a mediator that controls and regulates the movement transition, ensuring it only occurs at the appropriate intermediate position.
Solution Approach 2:
The interlock element is designed to automatically engage and disengage based on the position of the four-bar linkage assembly. As the seat assembly moves forward to the easy entry range, the interlock element self-activates to lock the seat cushion in the easy entry position. When the intermediate position is reached, the interlock element automatically releases, allowing the seat cushion to transition to the design position without requiring additional control mechanisms.
2Ease of operation
If the seat assembly allows free movement between positions, then ease of operation is improved, but measurement precision of seat position along the floor deteriorates
Solution Approach 1:
The interlock element serves as a mediator that defines specific positional states (easy entry position and design position) along the floor. By engaging with the striker pin at predetermined locations, it establishes accurate reference points for seat position measurement, thereby improving position accuracy while maintaining operational freedom between these defined ranges.
Solution Approach 2:
The system changes the state parameter of the seat cushion from locked to unlocked at specific positions along the floor. The interlock element controls this parameter change by engaging the striker pin at the easy entry position (preventing movement) and disengaging at the intermediate position (allowing movement), thereby creating distinct, measurable positional states with high precision.
3Reliability
If an interlock mechanism is added to prevent premature shifts, then reliability is improved, but device complexity increases
Solution Approach 1:
The interlock mechanism is segmented into distinct functional components: an interlock hook on the interlock element, a striker pin on the front link, and a return spring. This segmentation allows each component to perform its specific function independently while working together as a integrated system, making the complex mechanism easier to manufacture, assemble, and maintain.
Solution Approach 2:
The interlock element serves multiple functions: it locks the seat cushion in the easy entry position, defines the intermediate position for transition, and works with the return spring to provide automatic engagement and disengagement. This multi-functionality reduces the need for separate components, thereby managing device complexity while maintaining high reliability.
4Measurement precision
If the seat cushion is locked in easy entry position during forward movement, then position control is improved, but ease of operation for entry/exit deteriorates
Solution Approach 1:
The interlock mechanism operates periodically: it locks the seat cushion in the easy entry position when the seat assembly is in the easy entry range (facilitating occupant entry/exit), and automatically releases when the intermediate position is reached (allowing seat adjustment). This periodic locking and releasing cycle ensures both precise position control and ease of operation at appropriate times.
Solution Approach 2:
The interlock element transitions from a static locked state to a dynamic unlocked state based on the position of the four-bar linkage assembly. The return spring provides dynamic force to automatically disengage the interlock hook from the striker pin when the intermediate position is reached, enabling the seat cushion to move freely for occupant comfort while maintaining control during forward movement.
Data Source
Figure 1
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Figure 3A~3C
AI summary
A seat assembly for movement between a plurality of positions within an automotive vehicle includes a seat back pivotally coupled to a seat cushion and a seat track assembly with a sliding track repositionable along a fixed track for movement of the seat assembly between a forward position and a rearward position. A linkage assembly extends between the seat cushion and the sliding track for movement of the seat cushion between an easy entry position and a design position. An interlock element is pivotally coupled to the sliding track. Movement of the seat assembly from the forward position to the rearward position pivots the interlock element from a locked condition engaged with the linkage assembly for holding the seat cushion in the easy entry position, to an unlocked condition disengaged from the linkage assembly for allowing movement of the seat cushion to the design position.