Compact Bus Door Drive Using Roller Traction Inversion
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Solution Overview
Problem
Vehicle door drives for buses face a design conflict between requiring a wide door for easy access and a compact drive mechanism, with existing solutions being limited by the need for a small axial installation length and the inability to handle door warping or buckling due to high temperatures.
Innovation Solution
A compact vehicle door drive mechanism using a traction drive with a roller and a coupling mechanism, where the actuator is coupled to the axis of rotation of a roller, allowing a large door movement with a small actuation path, and incorporating a multifunctional piston-cylinder unit for enhanced performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a wide vehicle door is used to allow comfortable entry and exit, then passenger access is improved, but the axial length of the door drive increases
Solution Approach 1:
Instead of directly coupling the actuator to move the door along its full stroke, the patent inverts the approach by using a roller that rotates around an instantaneous center of rotation. The traction element wraps around this roller, creating a mechanical advantage where a small actuator stroke generates a large door movement through the rotational geometry.
Solution Approach 2:
The patent introduces a roller as an intermediary component between the actuator and the door. This roller, wrapped by a traction element, acts as a mediator that transforms the linear actuator movement into rotational motion, which then translates to the door's opening/closing movement through the coupling mechanism.
2Productivity
If a piston-cylinder unit is used for vehicle door actuation, then the stroke corresponds to the door opening/closing stroke, but the installation volume increases
Solution Approach 1:
The patent inverts the traditional piston-cylinder configuration by positioning the roller outside the cylinder housing and allowing the piston rod to extend from both sides. This inversion enables the use of a double-acting cylinder where the rod can be actuated from either side, reducing the overall axial length required for the same door stroke.
Solution Approach 2:
The patent implements a nested configuration where the roller is positioned within or adjacent to the cylinder housing, and the piston rod extends through the housing. This nesting arrangement allows compact integration of the actuation components, minimizing the overall installation volume while maintaining full door actuation capability.
3Reliability
If the chain or cable is positioned away from the furnace opening, then exposure to heat and flames is reduced, but design possibilities are limited
Solution Approach 1:
The patent uses the roller and traction element system as an intermediary mechanism that allows the drive components to be positioned in a protected location while still effectively actuating the door. The roller acts as a mediator that transfers the actuation force from the protected actuator location to the door, enabling both heat protection and design flexibility.
Solution Approach 2:
The patent resolves the spatial constraint by changing the dimensional arrangement of components. Instead of linearly positioning components along the door stroke path, the roller rotates in a different dimensional plane, allowing the actuator to be positioned away from the door while still providing full actuation capability through rotational mechanics.
Data Source
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AI summary
The invention relates to a vehicle door drive (1) for a bus. The vehicle door drive (1) has an actuator (2) which is coupled to the vehicle door via a traction drive (19). By selecting the position of the instantaneous center of rotation of a roller (7) of the traction drive (19), the actuation path of the actuator (2) can be doubled relative to the travel path of the vehicle door.