Exit Device Push Force Reducer With Biasing Slide Mechanism
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Solution Overview
Problem
Existing exit devices face challenges in complying with updated ADA requirements for reduced actuation force, particularly with traditional door bolts and vertical rods, which can lead to non-compliance with other safety and security standards when altered for lower push force.
Innovation Solution
Incorporation of biasing members, such as springs, to reduce the force required to actuate exit devices by coupling them to movable components like arms, slides, and levers, ensuring compliance with ADA requirements without compromising other performance standards.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If traditional door bolts and vertical rods are used in exit devices, then security and structural strength are improved, but the actuation force exceeds ADA requirements
Solution Approach 1:
The exit device is divided into multiple functional components: a push bar for actuation, an arm for motion transmission, a slide for linear movement, and a rod for bolt control. This segmentation allows each component to be optimized independently, with the slide mechanism specifically designed to reduce actuation force while the rod maintains structural strength for security.
Solution Approach 2:
A slide mechanism is introduced as an intermediary component between the arm and the rod. The slide converts rotational motion from the arm into linear motion that retracts the bolt, while biasing members attached to the slide provide mechanical advantage to reduce the actuation force required on the push bar.
2Ease of operation
If biasing members are added to reduce actuation force, then ADA compliance is improved, but device complexity increases
Solution Approach 1:
Biasing members are attached to the slide mechanism to automatically provide the force reduction needed for ADA compliance. The biasing members engage with the slide's movement, requiring no additional user action or complex control systems. The mechanism self-regulates the actuation force through the mechanical interaction between the biasing members and the slide's linear motion.
3Ease of operation
If the push bar actuation force is reduced to meet ADA standards, then accessibility is improved, but the ability to maintain secure door engagement may be compromised
Solution Approach 1:
The exit device employs dynamic motion through the arm and slide mechanism. When the push bar is actuated, the arm rotates and the slide moves linearly to retract the bolt. This dynamic sequence allows the system to maintain secure engagement during normal conditions while enabling easy release when actuated, achieving both reliability and accessibility.
Solution Approach 2:
The arm component utilizes curved or rotational geometry to convert the linear push force from the push bar into rotational motion. This curvature allows for efficient force transmission and mechanical advantage, reducing the actuation force needed while maintaining reliable bolt engagement through the rotational-to-linear motion conversion.
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 solution effectively reduces the actuation force to 5 lbf or less, maintaining compliance with ADA standards while minimizing complexity and cost, and allowing for various door configurations including vertical surface rods.
Implementation Method 1
one or more biasing members coupled to the slide and configured to bias the slide to the second slide position, thereby reducing a force to move the push bar from the unactuated position to the actuated position
Data Source
AI summary
Exit device push force reducers are disclosed. An exit device includes a push bar movable between an actuated position and an unactuated position. An arm is operatively coupled to the push bar and is movable between a first arm position and a second arm position. A slide is operatively coupled to the arm and is movable between a first slide position and a second slide position. Movement of the push bar from the unactuated position to the actuated position moves the arm from the first arm position to the second arm position. Movement of the arm from the first arm position to the second arm position moves the slide from the first slide position to the second slide position. One or more biasing members are coupled to the slide and are configured to bias the slide to the second slide position, thereby reducing a force to move the push bar from the unactuated position to the actuated position.