M-Shaped Pull Spring Mechanism for Tool-Less PCB Removal
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Solution Overview
Problem
Existing mechanisms fail to efficiently remove printed circuit board (PCB) and bezel assemblies from card guides without tools, particularly in scenarios with limited space, restricted access, and concealed locations, where traditional methods like finger grasping or tool usage are impractical.
Innovation Solution
The apparatus employs M-shaped pull springs attached to the PCB and bezel assembly, which are compressed when a cover is closed and extend to provide knobs for manual removal when the cover is opened, allowing tool-less ejection without protruding from the enclosure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If PCB and bezel assemblies are positioned surface-to-surface with minimal spacing, then space utilization is improved, but accessibility for manual removal deteriorates
Solution Approach 1:
The patent introduces pull knobs as intermediary elements that extend from the bezel assembly. These knobs serve as mediators between the user and the tightly spaced PCB assembly, providing a grasping surface that extends into the accessible space zone. The knobs allow users to apply force for removal even when the bezel itself is inaccessible due to minimal spacing.
Solution Approach 2:
The pull knobs extend in a dimension perpendicular to the front face of the bezel, creating a protrusion that reaches into the accessible space zone. This dimensional extension allows users to interact with the assembly from the front without needing to reach around the sides or access the back, solving the accessibility problem created by surface-to-surface positioning.
2Reliability
If side access is restricted by sheet metal cage and outer cover, then security and protection are improved, but ease of removal deteriorates
Solution Approach 1:
The pull knobs act as intermediaries that bridge the gap between the restricted side access and the need for removal capability. Instead of requiring users to reach around the sides through the cage opening, the knobs extend from the front, providing a direct access path that bypasses the security restrictions while maintaining both security and ease of removal.
3Shape
If front access is permitted only with tight-fitting cover, then concealment and aesthetics are improved, but ease of removal deteriorates
Solution Approach 1:
The pull knobs are pre-positioned on the bezel assembly in a retracted state that is concealed by the closed cover. When the cover is opened, the springs automatically push the knobs into an extended position, making them available for grasping. This preliminary positioning allows the assembly to maintain its concealed aesthetic appearance while ensuring removal capability is ready when needed.
Solution Approach 2:
The pull knobs are designed to be dynamic rather than static - they can be in a retracted concealed position when the cover is closed, and automatically extend to an accessible position when the cover is opened. This dynamic behavior allows the system to transition between aesthetic concealment and functional accessibility without requiring manual intervention.
4Ease of operation
If tool-less removal is implemented for CRUs, then ease of operation is improved, but device complexity deteriorates
Solution Approach 1:
The pull spring mechanism is designed to be self-actuating - when the cover is opened, the springs automatically push the knobs into the extended position without requiring any additional actuators, motors, or complex control systems. The mechanism uses the simple mechanical energy stored in the compressed springs to automatically make the knobs accessible, achieving tool-less removal without significant complexity.
Solution Approach 2:
The pull spring changes its physical state between compressed and uncompressed configurations to control the position of the knobs. This parameter change (spring compression/expansion) provides a simple binary state mechanism that transitions the knobs between concealed and accessible positions, achieving tool-less operation through a single physical parameter rather than complex control systems.
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 efficient, tool-free removal of PCB and bezel assemblies in constrained spaces, suitable for Customer Replaceable Units (CRUs), maintaining spring action for extended periods without electrical conductivity, and is cost-effective.
Implementation Method 1
A pull spring is attached to opposing sides of the PCB and bezel assembly. Each pull spring includes a generally M-shaped spring.
Implementation Method 2
the pull spring is formed of an electrically nonconductive material, such as a plastic material, that retains spring action while being compressed for an extended period of time
Data Source
AI summary
Apparatus for removing a printed circuit board (PCB) and bezel assembly from a unit includes a pull spring is attached to opposing sides of the PCB and bezel assembly. Each pull spring includes a generally M-shaped spring. A first end of the M-shaped spring includes a first pin carrying a knob. The first pin extends through an opening in the bezel and the knob is disposed within a recessed portion of the bezel and is generally flush with a front face of the bezel with the M-shaped spring compressed in a normal constrained position. In an extended position when the M-shaped springs return to a substantially uncompressed state, the knobs are pushed forward and are spaced apart in front of the bezel, enabling a person to grip and pull each knob to remove the PCB and bezel assembly from the unit in which it is installed.