Power Seat Slide Screw Support Segmentation
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Solution Overview
Problem
Existing power seat slide apparatuses face issues with irregular sliding and rotation of the screw shaft due to rigid fixation of the worm wheel and screw shaft, leading to noise and difficulty in supporting long screw shafts, as well as structural challenges in withstanding loads during sudden vehicle stops.
Innovation Solution
A power seat slide apparatus with a lower rail and upper rail configuration, featuring a screw member supported by retaining brackets with slide nut members that sandwich the screw, allowing stable rotation and sliding while distributing loads away from the gearbox, thus preventing noise and enhancing structural robustness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the worm wheel and screw shaft are rigidly fixed, then the structure is simplified, but the screw shaft cannot be securely supported leading to irregular sliding motion and noise
Solution Approach 1:
The support structure is segmented into multiple independent support points along the screw shaft. Instead of a single rigid fixation, the screw shaft is supported at multiple locations by bearings mounted on the rail, dividing the support function into discrete segments that collectively provide stable support throughout the shaft's length.
Solution Approach 2:
Bearings are introduced as intermediary elements between the screw shaft and the rail. These bearings serve as mediators that provide rotational support to the screw shaft while allowing it to rotate freely, eliminating direct rigid fixation and preventing interference between the worm wheel-screw shaft engagement and the support structure.
2Reliability
If the gear box is designed to withstand sudden stop loads, then reliability is improved, but the gear box size and structure become more complex
Solution Approach 1:
The load-bearing function is extracted from the gear box and transferred to the rail structure. The rail is designed to withstand the sudden stop loads and transmit them directly to the vehicle floor, while the gear box is relieved of this burden and only needs to provide rotational drive torque, significantly reducing its structural requirements.
Solution Approach 2:
Instead of having the gear box bear the sudden stop loads and transmit them through the screw shaft, the load path is inverted: the rail directly bears these loads and transmits them to the floor, while the screw shaft-gear box system only handles the lighter rotational drive loads.
3Device complexity
If the screw shaft is made longer to span the rail, then the structure is simplified, but support stability deteriorates due to interaction between worm wheel engagement and screw-nut engagement
Solution Approach 1:
Bearings are introduced as intermediary support elements at multiple points along the screw shaft. These bearings prevent direct contact and interaction between the worm wheel engagement and the screw-nut engagement by providing independent rotational support, allowing the screw shaft to rotate freely without interference from the support structure.
Solution Approach 2:
The support structure is segmented into multiple independent bearing locations along the screw shaft. This segmentation prevents the formation of a single long unsupported span, dividing the screw shaft into multiple shorter segments that are each independently supported, thereby maintaining stability even over long distances.
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 solution ensures stable and silent sliding of the seat, reduces noise during adjustment, and simplifies the gearbox structure by distributing loads effectively, improving the apparatus's rigidity and reducing its size and weight.
Implementation Method 1
a feed nut member arranged on one of the lower rail (21) and the upper rail (22) and threaded onto the screw member (23)
Implementation Method 2
a first slide nut member (43) and a second slide nut member (44) arranged on the screw member (23) so as to oppose each other via the retaining bracket (31) and cooperatively sandwiching the retaining bracket (31) in an axial direction of the screw member (23)
Data Source
AI summary
A power seat slide apparatus includes a lower rail adapted to be provided on a floor of a vehicle, an upper rail slidably supported by the lower rail and adapted to support a seat for a vehicle, a screw member supported by the upper rail and the lower rail, a feed nut member arranged on one of the lower rail and the upper rail and threaded onto the screw member, a retaining bracket arranged on the other one of the lower rail and the upper rail and the screw member being positioned in the retaining bracket, a first engaging member and a second engaging member arranged on the screw member so as to oppose each other via the retaining bracket and cooperatively sandwiching the retaining bracket in an axial direction of the screw member, and a drive unit transmitting a rotating drive force to the screw member.