Door Hold Open Arm Assembly Soffit Ramp Design
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Solution Overview
Problem
Conventional hold open arm assemblies with spring-biased plungers and rivets experience excessive wear and premature failure due to significant friction between the plunger and rivet, leading to operational issues.
Innovation Solution
A soffit ramp with a sloped surface is introduced, allowing the plunger to engage and slide along the ramp, reducing horizontal force on the rivet and incorporating a recessed area to receive the rivet head, thereby minimizing wear and extending the lifespan of the components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a spring-biased plunger is used to engage with a rivet head to hold the door open, then the door can be held in the open position, but significant friction occurs between the plunger and rivet causing excessive wear and premature failure
Solution Approach 1:
A soffit ramp is introduced as an intermediary component between the plunger and the rivet head. The ramp provides a sloped surface that guides the plunger and distributes the engagement force, reducing direct friction between the plunger and rivet. The ramp acts as a mediator that enables the hold open function while minimizing wear on the contacting surfaces.
Solution Approach 2:
The invention changes the geometric parameters of the engagement interface by introducing a sloped surface on the soffit ramp. This slope angle modifies the force vector during plunger-rivet engagement, reducing the horizontal friction component while maintaining the vertical holding force. The parameter change transforms the engagement from direct contact to a more favorable angled contact that reduces wear.
2Device complexity
If the plunger directly engages with the rivet head, then the door can be held open with simple mechanics, but lateral force and friction cause excessive wear
Solution Approach 1:
The soffit ramp serves as a mediator that introduces additional geometry to the engagement interface. While maintaining the basic plunger-rivet hold open mechanism, the ramp provides a sloped surface that reduces harmful lateral forces and friction between the plunger and rivet head during engagement.
3Force
If the plunger is forced down the side of the rivet, then engagement occurs, but significant friction results in excessive wear and premature failure
Solution Approach 1:
The sloped surface on the soffit ramp changes the parameter of force distribution during engagement. Instead of the plunger being forced directly against the rivet head with high friction, the slope allows the plunger to engage at an angle, distributing the force and reducing the friction component that causes 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
The sloped surface design reduces friction and wear, prolonging the life of the plunger and rivet, and effectively maintains the door in the open position without premature failure.
Implementation Method 1
a resiliently biased plunger having a free end is received in the housing
Implementation Method 2
contact is made between the side of the plunger and the side of the rivet, resulting in lateral force between the two parts, and significant friction as the plunger is forced down the side of the rivet
Data Source
AI summary
A hold open arm assembly for a door closer to facilitate access to the holding feature by a resiliently biased plunger on a closer arm that is mounted to a soffit plate. A soffit ramp may extend from the soffit plate to provide a sloped surface for engagement by the plunger, leading to the plunger being gradually depressed as the door continues to open and receiving in a recessed area of its free end a rivet head at the soffit plate to hold the door open. When the first arm member pivots relative to the soffit plate and the plunger approaches the head, the plunger engages the sloped surface of the soffit ramp, slides along the sloped surface toward the head, and receives at least a portion of the head in the opening in the free end.