Camming Element Dogging Mechanism for Exit Devices
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Solution Overview
Problem
Conventional exit devices require the depression of a push bar to dog the exit device, which can be inconvenient and may not allow for easy retention of the latch in an unlatched position without actuation.
Innovation Solution
A dogging mechanism that includes a camming element configured to move between a dogged state and an undogged state, allowing a user to dog the exit device without depressing the push bar by using a key or tool to rotate the camming element, thereby retaining the latch in an unlatched position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a conventional push bar mechanism is used to dog the exit device, then the latch can be held in an unlatched position, but the operation becomes inconvenient and requires actuation of the push bar
Solution Approach 1:
The dogging mechanism is segmented into distinct functional components: a camming element with curved slots for directional movement, a latch assembly with roller and arm, and a push bar assembly. This segmentation allows each component to perform its specific function independently, enabling the camming element to control dogging without requiring push bar actuation, thus improving ease of operation while maintaining manageable complexity through modular design
Solution Approach 2:
The camming element acts as an intermediary between the user's manual input and the latch mechanism. By introducing this intermediate component with its curved slot geometry, the system translates simple linear or rotational input into the complex coordinated movements needed to dog the exit device, eliminating the need to actuate the push bar while keeping the overall mechanism relatively simple
2Ease of operation
If the push bar must be depressed to dog the exit device, then the mechanism remains simple, but user convenience is reduced and access is hindered
Solution Approach 1:
The camming element is designed with curved slots that pre-configured the mechanical path for latching and dogging operations. The geometry of the slots anticipates the required movement sequence, allowing the latch roller to follow a predetermined path that achieves dogging without push bar actuation. This preliminary design of the mechanical path improves user convenience and access efficiency by eliminating unnecessary steps
Solution Approach 2:
The mechanism employs dynamic elements including the movable camming element that can shift position within its curved slots, and the roller that moves along the latch arm. This dynamic design allows the system to adapt its configuration during operation, enabling smooth transitions between latched and dogged states without requiring forceful push bar depression, thereby improving both user convenience and access efficiency
3Ease of operation
If a camming element with curved slots is used, then the latch can be retained in unlatched position without push bar actuation, but the device complexity increases
Solution Approach 1:
The camming element combines multiple functions into a single component: it guides the latch roller through curved slots, provides the dogging action through its movement, and maintains the unlatched position through its geometric configuration. The latch arm and roller are merged into an integrated assembly that works with the camming element. This merging reduces the number of separate parts needed, allowing easy latch retention without push bar actuation while controlling overall device complexity
Solution Approach 2:
The camming element incorporates curved slots with specific radii of curvature that guide the latch roller through arcuate paths. This curvature is essential for achieving the dogging function, as it converts linear camming motion into the rotational or lateral movement needed to position the latch arm. The curved geometry enables easy latch retention in the dogged position while maintaining a relatively simple mechanical structure through elegant geometric design rather than complex mechanisms
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
Enables the exit device to be easily dogged without actuating the push bar, allowing for convenient retention of the latch in an unlatched position, which reduces congestion and improves user access.
Implementation Method 1
a camming element configured to move between a dogged state and an undogged state, and at least one slot in the camming element configured to permit movement of the camming element between the dogged and undogged states
Data Source
AI summary
A dogging mechanism for an exit device may include a camming element that is configured to rotate between an undogged position and a dogged position. The dogging mechanism may include a first linkage operatively coupled to a latch of the exit device and a second linkage operatively coupled to the camming element. The first linkage may be fixed to the camming element such that movement of the camming element between the undogged position and the dogged position moves the latch between a latched position and an unlatched position, respectively. The camming element may include at least one slot that is at least partially curved, and the slot may receive a pin of the second linkage such that the slot is movable relative to the second linkage to move the camming element between the undogged and dogged positions.