US 4,541,136 · Granted 1985-09-17
The Air Cell Cushion That Stays Firm No Matter Where You Sit
Imagine a cushion made of dozens of tiny inflatable air cells all connected inside. When you sit on it, some cells get squished, but they all stay at the same air pressure—so every cell pushes back equally hard on you. The clever part: the cells touch each other when inflated, creating one smooth, supportive surface instead of a lumpy one.
The plain-English version
What it protects
The claim covers the specific design of an inflatable cushion where air cells are arranged in rows on a flexible base, all connected internally so they maintain equal pressure when compressed. What's protected here is the geometry of each air cell—four fins with special side walls and inclined pedestals that make the cells contact each other smoothly when inflated, creating a uniform supporting surface. The base itself and the way the cells connect through it are also part of the protected design.
Why it matters
This patent solves a real problem with air cushions: uneven support and uncomfortable pressure points. By engineering the cells to stay interconnected and touch each other symmetrically, the design ensures consistent support regardless of where a load is applied. This matters for comfort-critical applications like hospital beds, wheelchair cushions, and specialized seating where pressure distribution can affect health outcomes. The manufacturing method—dipping a mandrel in latex—was also novel for its time.
Real-world use
You'd find this technology in medical pressure-relief cushions used in hospitals and care facilities, designed to prevent bedsores by distributing a patient's weight evenly across the entire surface.
Original USPTO abstract
An inflatable air cushion has a base and air cells arranged in rows upon and projecting away from the base, with the outer ends of the air cells forming a supporting surface. The base and air cells are formed from a flexible elastomeric material and are in communication through the base, so that when some of the air cells are deflected by a supported load, all the air cells nevertheless remain at the same internal pressure. Thus, those air cells that are against the load exert equal forces on the load, irrespective of the amount of deflection. Adjacent air cells when inflated are adapted to contact each other along their sides so as to provide a generally continuous supporting surface. To this end, each air cell when deflated has four fins arranged symmetrically about its axis, with each fin having spaced apart side walls. The side walls of adjacent fins are connected near the center of the air cell to provide depressions that open out of the air cells. Between each depression and the base is an inclined wall, and the four inclined walls serve to provide the air cell with a square pedestal. When the air cells are pressurized, the side walls of their fins and the inclined pedestal walls move outwardly and contact the opposite side walls and pedestal walls on adjacent air cells, so the load supporting surface is generally uniform. The air cells and connecting portions of the base are formed on a mandrel which is dipped in a latex solution.
Patent details
- Publication number
- US 4,541,136
- Filing date
- 1983-09-01
- Grant date
- 1985-09-17
- Assignee
- Graebe Robert H
- Inventor(s)
- GRAEBE; ROBERT H.
- CPC class
- A47C27/081
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