Seat assembly for a wheelchair

The wheelchair seat assembly uses dual linear actuators driven by a single electric motor through flexible shafts to achieve high torque and adjustable backrest angles, addressing the limitations of traditional systems by reducing frame stiffness and height.

EP4763172A1Pending Publication Date: 2026-06-24PERMOBIL
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Patent Information

Authority / Receiving Office
EP · EP
Patent Type
Applications
Current Assignee / Owner
PERMOBIL
Filing Date
2024-12-20
Publication Date
2026-06-24

AI Technical Summary

Technical Problem

Traditional wheelchair backrest angle adjustment systems require a single actuator at the lateral side, necessitating a torsionally stiff frame to withstand high operational forces, which increases complexity and height, and often lack the capability to achieve high torque.

Method used

A seat assembly for wheelchairs utilizing two linear actuators driven by a single electric motor via flexible shafts, allowing symmetric force distribution and reducing the need for a torsionally stiff frame, with a flexible shaft transferring rotational motion to each actuator, enabling high torque and adjustable backrest angles without increasing height.

Benefits of technology

The system achieves high torque of 500 Nm, reduces the wheelchair's overall height, and allows for adjustable backrest angles with symmetric force distribution, minimizing the need for a torsionally stiff frame.

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Abstract

A seat assembly (1) for a wheelchair, comprising: a seat base (3), a backrest holding frame (5) including: a first bracket (7a) connected to the seat base (3), a second bracket (7b) connected to the seat base (3), and an intermediate member (9) extending between and being pivotably connected to the first bracket (7a) and the second bracket (7b); a first linear actuator (11) pivotably connected to the first bracket (7a) and connected to the intermediate member (9), a second linear actuator (13) pivotably connected to the second bracket (7b) and connected to the intermediate member (9), an electric motor assembly (17) mounted to the intermediate member (9), and a first flex shaft (19a) connected to the electric motor assembly (17) and to the first linear actuator (11), the first flex shaft (19a) being configured to be rotated by operation of the electric motor assembly (17) to thereby transfer rotational motion from the electric motor assembly (17) to actuate the first linear actuator (11), wherein the second linear actuator (13) is operatively connected to the electric motor assembly (17) to actuate the second linear actuator (13), wherein actuation of the first linear actuator (11) and the second linear actuator (13) causes a change in an angle of the intermediate member (9) relative to the first bracket (7a) and relative to the second bracket (7b).
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