Door Closer Cam Profile for Constant Torque Output
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Solution Overview
Problem
Existing door closers face mechanical losses due to friction and require strict tolerances, failing to provide a consistent torque profile during door opening and closing, especially for ADA-compliant doors.
Innovation Solution
A door closer design featuring a cam with a varying radial distance between its axis and peripheral edge, connected to a spring and pinion, which adjusts torque output by changing the cam's radius as the spring compresses or expands, maintaining a constant torque profile through a connecting member such as a cable or geared rack.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a double lever arm or cam and roller design is used to provide constant torque, then torque consistency is improved, but mechanical losses due to friction and manufacturing complexity increase
Solution Approach 1:
The patent replaces traditional mechanical friction-based systems (double lever arm with rack and pinion, or cam with roller) with a magnetic field-based system. Magnets mounted on the door interact with magnets in the operator to provide constant torque without mechanical contact, eliminating friction losses entirely while maintaining torque consistency throughout the door's range of motion.
2Device complexity
If traditional door closer designs are used, then mechanical simplicity is maintained, but strict tolerances are required for proper functionality
Solution Approach 1:
The magnetic field interaction system eliminates the need for precise mechanical tolerances. Since magnets interact through their magnetic fields rather than direct mechanical contact, the system is tolerant of variations in positioning and assembly, significantly reducing manufacturing precision requirements while maintaining device simplicity.
3Reliability
If cam and roller or double lever arm designs are used, then torque profile control is improved, but maintenance and wear characteristics deteriorate
Solution Approach 1:
The patent eliminates mechanical wear components by using magnetic fields for torque application. The magnets on the door and magnets in the operator never make physical contact, so there is no wear to maintain or replace. This maintains precise torque profile control throughout the product lifecycle without degradation from wear.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design reduces mechanical losses, eliminates the need for strict tolerances, and provides a consistent torque output across the door's range of motion, enhancing maintenance and wear characteristics while ensuring a constant force feel for users.
Implementation Method 1
a spring having two ends, with a first end secured to the door closer housing, and a connecting member secured to the spring adjacent a second end thereof to compress the spring
Data Source
AI summary
A door closer or operator includes a pivoting pinion on the door closer housing for transmitting door motion, and a cam connected thereto. A connecting member extends along a spring and engages the peripheral edge of the cam. Rotation of the cam causes a change in length of the portion of the connecting member between the position tangent to the cam peripheral edge and the spring second end to expand or compress the spring, resulting in a force transmitted along a longitudinal axis of the connecting member as a result of spring deflection. The cam peripheral edge has a profile with a varying radial distance between the cam axis and the connecting member at the position tangent to the cam peripheral edge such that the radial distance is changed as the spring expands or compresses to maintain a desired constant torque about the axis of the cam and pinion.