Seat suspension
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Solution Overview
Problem
Active suspension systems for motor vehicle seats can cause uncomfortable pressure on the thighs and loss of contact with foot pedals due to tilting and translation motions, which existing systems attempt to mitigate but often result in disconcerting movements and varying waist angles.
Innovation Solution
A seat support mechanism that constrains seat motion by pivoting the seat bottom about a virtual horizontal axis located farther from the front edge than the knees, maintaining a constant seat back angle and reducing tilt variations, thereby minimizing foot pedal force changes and waist angle discomfort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the seat is moved up and down relative to the floor in active suspension systems, then road-induced vibration in the seat is reduced, but the distance from the seat to floor-mounted control pedals changes causing uncomfortable pressure on the back of the user's thighs and potential loss of contact of the driver's feet with the pedals
Solution Approach 1:
The patent introduces a new degree of freedom by allowing the seat bottom to tilt independently of vertical motion. Instead of only moving the seat up and down, the system now controls both vertical position and tilt angle, transforming a one-dimensional problem into a two-dimensional control problem that simultaneously addresses vibration reduction and pedal contact maintenance
Solution Approach 2:
The system dynamically adjusts the seat bottom tilt angle in response to vertical motion. As the seat moves vertically, the control system modifies the tilt angle to compensate for changes in distance to the pedals, creating a dynamic compensation mechanism that maintains foot contact throughout the suspension travel range
2Reliability
If linkages are used to control forward/backward and tilting motions of the seat bottom, then loss of contact between feet and pedals is prevented, but the tilting of the seat bottom relative to the seat back causes uncomfortable varying angle at the waist
Solution Approach 1:
The patent carefully controls the magnitude of tilt angle changes as a parameter. By limiting the tilt angle variation to a small range, the system maintains foot contact with pedals while minimizing the variation in waist angle that causes discomfort. The tilt parameter is optimized to balance pedal contact reliability with occupant comfort
3Reliability
If the seat is translated fore and aft while the vehicle is in motion, then foot contact with pedals is maintained, but some drivers find this motion disconcerting
Solution Approach 1:
Instead of translating the seat fore and aft in the horizontal direction, the patent uses vertical tilting motion to achieve the same goal of maintaining foot contact. This replaces one type of unwanted motion (horizontal translation) with a different type of motion (vertical tilting) that is less perceptible and less disconcerting to drivers
Data Source
AI summary
A seat support mechanism that is adapted to constrain motion of a bottom of a seat relative to a floor as the seat bottom moves up and down relative to the floor, where the seat has a seat back, and where the seat is constructed and arranged to support an occupant thereof above the floor, wherein the seat bottom has a front edge, and wherein the seat bottom supports the occupant's thighs with the knees in front of the front edge of the seat bottom. The seat support mechanism is constructed and arranged such that as the seat bottom is moved up and down, the seat support mechanism causes the seat bottom to pivot about a virtual lateral horizontal pivot axis located farther from the front edge of the seat bottom than the occupant's knees. The seat support mechanism is further constructed and arranged such that the back of the seat remains at a relatively constant angle to the floor as the seat bottom moves up and down and pivots.