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The existing wheelchair lifting device of rehabilitation bus is currently driven by a hydraulic cylinder. This research intends to replace the hydraulic cylinder with an electric cylinder, but the maximum driving force of the electric cylinder currently available on the market is only 6000N; therefore, this research will focus on reducing driving force of the existing wheelchair lifting device. It is hoped that the maximum driving and pulling force will be less than 6000N, so that the hydraulic cylinder can be replaced by an electric cylinder. Firstly, the relevant patents and existing wheelchair lifting device of rehabilitation bus are discussed. The patent of the supporting device (I720819) is cited, and the original sliding pair is replaced by a double link to push the platform turn over. The actuators (hydraulic cylinder) of wheelchair lifting device are mostly placed between the four connecting rods. In order to reduce the driving force of the system, this study moved the actuator to the rear of the mechanism and added auxiliary spring to the original position of actuator. The design concept (1) of this research is a reasonable choice, and the driving arm ratio is set to be 1.2~1.25 for force design. In this paper, the influence of the spring K value on the driving force is discussed, and the analysis and simulation is carried out by Inspire. It is found that when K=22.5N/mm, the driving and pulling forces required are both less than 6000N, which is smaller than the Max. driving force of electric cylinder on the market.
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