Sunrise Medical HHG, Inc. 於2012.7.3.向美國地方法院田納西州中區納什維爾分院(District Court for the Middle District of Tennessee Nashville Division)指控電動椅製造商Permobil Inc. 的M300及M400的中輪驅動電動輪椅系列產品侵害其US8,210,556號專利權，系爭專利為US7,896,394號專利的延續案。原告Sunrise及被告Permobil均為電動輪椅的重要製造廠商，產品包括各種行動輔具及其週邊配件，Sunrise的總部設於加州，Permobil則是一家瑞典公司，創辦人為一名醫生，二家公司都是以設計生產能讓患者獨立工作與享受生活的電動輪椅為目標。
Title: Midwheel drive wheelchair with independent front and rear suspension
Filing Date : 2012.2.13.
Issue Date : 2012.7.3.
A wheelchair includes a frame, and a front pivot arm pivotally mounted to the frame at a front pivot point, the front pivot arm having a caster for supporting the frame. A rear pivot arm is pivotally mounted to the frame at a rear pivot point, the rear pivot arm having a caster for supporting the frame. A ground engaging mid-wheel drive wheel is connected to the frame. A linkage connects the front and rear pivot arms to each other in a manner such that an upward or
downward rotation of one of the pivot arms about its pivot point causes rotation of the other pivot arm about its pivot point in an opposite rotational direction.