Cylindrical Lockset Sheet Metal Cage and Torque Plate
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Solution Overview
Problem
Conventional cylindrical locksets are bulky, expensive, and lack desired strength, durability, and versatility due to large cast spindle bearings and prominent trim, with cantilever-type knob catch assemblies often providing inadequate handle-retaining force.
Innovation Solution
A cylindrical lockset design featuring a multiple-compartment sheet metal lock cage subassembly with coaxially mounted spindle bearings, housed within a sheet metal cover cylinder, incorporating torsion springs for biasing spindles and a torque plate for torque transfer, utilizing stamped sheet metal components to reduce costs and enhance functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If large cast spindle bearings are used to house lever return springs, then reliability is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The lock body is divided into multiple compartments, with the spindle bearing separated from the spring housing. The spindle bearing is a simple cylindrical component that houses only the spindle, while the return springs are mounted in separate spring retainer plates within different compartments of the lock body.
Solution Approach 2:
The return springs are extracted from the spindle bearing housing and mounted separately in the lock body compartments. This eliminates the need for complex cast spindle bearings that integrate both functions, allowing the use of simpler machined or stamped components.
2Reliability
If internal rose cages are provided to house lever return springs, then reliability is improved, but device complexity and trim size increase
Solution Approach 1:
The lock body is segmented into multiple compartments, each housing specific components. The return springs are mounted in dedicated spring retainer plates within these compartments, eliminating the need for a single complex internal rose cage structure.
Solution Approach 2:
The lock body compartments serve multiple functions: housing the retractor, mounting return springs, and providing structural support. This multi-functional design eliminates the need for separate specialized housing structures like internal rose cages.
3Ease of manufacture
If cantilever-type knob catch assemblies are used, then ease of manufacture is improved, but reliability deteriorates due to inadequate handle-retaining force
Solution Approach 1:
The knob catch assembly is extracted from the spindle and mounted separately on the lock body. This allows the spindle to be a simple rotating component while the catch mechanism provides dedicated handle retention functionality with sufficient holding force.
Solution Approach 2:
The knob catch assembly acts as an intermediary between the spindle and the handle. It provides a separate mounting point on the lock body that delivers adequate retaining force without requiring the spindle itself to be overly complex or large.
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 design achieves a cost-effective, strong, and versatile lockset with improved handle retention and torque management, reducing component complexity and weight while maintaining compliance with Grade 1 lock standards.
Implementation Method 1
At least one spindle return torsion spring, for biasing a corresponding one of the spindles to a default position, is housed within a second lock cage compartment.
Implementation Method 2
a torque plate configured to be mounted adjacent a door face and coupled to a sheet metal lock cage assembly, for transferring torque from the lock cage subassembly to relatively radially distal trim posts
Data Source
AI summary
A cylindrical lockset comprises a multiple-compartment lock cage subassembly. A retractor is housed within a middle lock cage compartment. Spindle return torsion springs, for biasing corresponding handle-carrying spindles to their default positions, are housed within axially adjacent lock cage compartments. A torque plate transfers torque from the lock cage subassembly to relatively radially distal trim posts. A knob catch assembly seated in each handle-carrying spindle comprises a generally elliptically-shaped wrap around catch spring and a knob catch backup washer to resist axial loads produced by efforts to pull a handle off of the spindle. A key spindle provides a dog travel window defined by a closed, continuous edge of the key spindle, which window is positioned opposite of an axially-extending seam of the key spindle.