Indexing Cam Latch for Secure Door Locking
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Solution Overview
Problem
Existing latch apparatus lack improvements in selectively holding closure members in closed or release positions, and in providing secure locking and unlocking mechanisms using authorized inputs.
Innovation Solution
A latch apparatus with a rotatably movable handle connected to a shank, featuring an indexing cam mechanism that allows axial and rotational movement to change between locked and unlocked positions, and an optional lock cylinder for secure key-based operation, enabling the latch to hold doors in closed positions and allow release through authorized key input.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional lock structure with key, token, or biometric input is used, then security and authorized access control are improved, but device complexity increases
Solution Approach 1:
The latch apparatus is divided into distinct functional modules: a lock cylinder for key input, a cam mechanism for motion transformation, a striker for latching, and a door bolt for securing. This segmentation allows each component to perform its specific function efficiently while maintaining overall system security without excessive complexity.
Solution Approach 2:
The cam mechanism serves as an intermediary between the lock cylinder and the striker. When the key is rotated in the lock cylinder, it transforms the rotational motion into linear motion through the cam, which then actuates the striker to engage or disengage the door bolt. This intermediary mechanism provides secure key-based control while simplifying the overall actuation system.
2Device complexity
If a simple latch mechanism without locking structure is used, then device complexity is reduced, but the ability to provide secure locked condition is worsened
Solution Approach 1:
The latch mechanism employs dynamic components including a rotatable handle connected to a shank with a cam profile. The cam transforms rotational motion of the handle into linear motion of the striker, enabling the door bolt to move between locked and unlocked positions. This dynamic design provides secure locking while maintaining operational simplicity.
Solution Approach 2:
The cam mechanism automatically transforms the rotational motion of the handle into the linear motion required to actuate the striker and engage/disengage the door bolt. This self-service mechanism eliminates the need for separate actuators or complex control systems, providing secure locking with minimal device complexity.
3Manufacturing precision
If the shank is held in fixed axial position, then manufacturing precision is improved, but the ability to enable rotational movement for unlocking is worsened
Solution Approach 1:
The shank is designed with a cam profile that allows it to move axially relative to the latch body when the handle is rotated. The cam surface guides the axial movement, ensuring precise motion control while enabling the rotational operation of the handle to effectively actuate the striker and door bolt for unlocking.
Solution Approach 2:
The mechanism converts the rotational motion of the handle into axial linear motion of the shank through the cam profile. This dimensional transformation allows the handle rotation (one dimension) to control the axial position of the shank (another dimension), enabling unlocking operation while maintaining manufacturing precision through the guided cam surface.
Data Source
AI summary
A latch (10) is usable to selectively hold a closure member such as a door (188) in a closed position. The latch includes a body (12) which has a manually engageable handle (18) on a front side thereof. A shank (30) is in rotationally movable connection with the handle. The shank extends through the body and into an indexing cam bore (58) on the back side of the body. The shank is both axially and rotationally movable about a cam bore axis (62). An indexing cam (88) is connected to the shank. The shank is in operative connection with a striker (102). The striker is rotationally movable responsive to rotation of the handle between a latched position and unlatched position when the shank is in a second axial position. When the shank is in a first axial position, the shank is held in a fixed rotational position by the indexing cam, and the striker is held in the latched position. A cam bolt (164) is movably engageable with the striker to hold the striker in the latched position. The cam bolt is in operative connection with a lock cylinder (142). The lock cylinder is rotatable in engagement with a correct key to selectively position the cam bolt.