Double Draw Bar Spring Mechanism for Door Handle Return
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Solution Overview
Problem
Existing door opening mechanisms fail to efficiently return to a neutral or home position and maintain that position against ambient forces, such as gravity, without additional manual intervention.
Innovation Solution
A low-profile power pack assembly with interlocked slide arms and compression springs, integrated into a door handle system, which uses a spindle hub and cam mechanism to compress springs and store potential energy for automatic return to the home position, eliminating the need for expansion or torsion springs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If independent springs are used for each slide arm, then each arm can be biased independently, but the return force is insufficient and the mechanism is more complex
Solution Approach 1:
The patent combines two independent spring mechanisms into a single integrated spring assembly. The spring is configured to simultaneously bias both slide arms, with the arms interlocked such that movement of one arm compresses the spring, which then provides restoring force to both arms. This merging doubles the return force compared to independent springs while reducing the number of separate spring components and simplifying the overall mechanism.
2Force
If expansion or torsion springs are used, then return force can be provided, but reliability is reduced and cost increases
Solution Approach 1:
Instead of using expansion springs or torsion springs that rely on rotational or volumetric elasticity, the patent inverts the approach by using a compression spring in a linear configuration. The compression spring is positioned to be compressed by the movement of the slide arms along their longitudinal axes, converting the rotational motion of the cam into linear compression of the spring. This inverted configuration provides more reliable operation and lower cost compared to expansion or torsion springs.
3Extent of automation
If a cam mechanism is used to compress springs, then automatic return to home position is achieved, but the device profile increases
Solution Approach 1:
The patent utilizes the radial dimension of the cam mechanism to achieve automatic return functionality without increasing the longitudinal profile of the device. The cam, mounted on the spindle hub, converts rotational motion into radial displacement that compresses the spring. The slide arms are configured to move in the longitudinal dimension while being actuated by the radial motion of the cam, effectively using a different spatial dimension to achieve automation while maintaining a compact overall profile.
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
Ensures reliable and cost-effective operation by providing twice the return force of independent springs, reducing wear and simplifying mechanisms, while maintaining the door lever in the home position indefinitely.
Implementation Method 1
a first compression spring retained between the first arm and the housing and a second compression spring retained between the second arm and the housing
Implementation Method 2
uses a spindle hub and cam mechanism to compress springs and store potential energy for automatic return to the home position
Data Source
AI summary
A double slide arm spring mechanism for biasing a primary mechanism to home position after operation and retaining the primary mechanism in the home position pending further operation. The double slide arm spring mechanism includes a pair of slideably interlocking arms each having a longitudinal frame member and a spring engaging flange at each end. The frame members are a disposed to engage one another while permitting relative sliding of the arms. The slide arms are interlocked such that one flange of each arm is situated between the two flanges of the other arm. Two compression springs are retained between the flanges of the arms such that sliding of either arm toward the other necessarily compresses both springs. Potential energy stored in the springs returns the slide to its neutral position when the operator is released thereby also returning the operator to its neutral position. The slide arms produce twice as much force to return operator to it neutral position as would be possible using springs of the same length operated independently.