Bed Side Rail Locking Mechanism for Controlled Lowering
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Solution Overview
Problem
Tubular side rails for beds often remain in the raised position due to their center of gravity alignment with the axis of rotation, leading to spontaneous downward movement and unlocking issues, and existing locking mechanisms are either complex, prone to friction malfunctions, or inconvenient to operate.
Innovation Solution
A bed side rail design featuring a torsion spring in the rotational bearing, an auxiliary bar, and a locking mechanism with a rotational actuating member and spring system that ensures the side rail remains locked in the raised position and only unlocks with deliberate force application, using a combination of torque and friction to prevent spontaneous movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the side rail is designed with rotational pins perpendicular to the bed plane, then the side rail can be lowered to allow patient access, but the side rail may remain in the raised position and not be locked in position
Solution Approach 1:
The patent introduces a counterweight mechanism that creates a torque imbalance to ensure the side rail spontaneously lowers when unlocked. The counterweight is positioned to create a moment that overcomes the weight of the side rail, ensuring reliable downward movement without requiring additional force from the operator.
Solution Approach 2:
The locking mechanism is designed to automatically lock the side rail in the raised position when engaged. The spring-loaded locking element automatically engages with the locking surface, providing self-locking functionality that maintains the raised position without requiring continuous operator intervention.
2Reliability
If additional bars are added to create torque for spontaneous lowering, then the side rail can be lowered more reliably, but the device complexity increases
Solution Approach 1:
The patent combines the counterweight function with the existing side rail structure by integrating the counterweight into the side rail assembly itself. This merging of functions eliminates the need for separate additional bars while still providing the necessary torque for spontaneous lowering, thus reducing overall device complexity.
Solution Approach 2:
The side rail structure is designed to serve multiple functions: it provides the structural support for the bed, incorporates the locking mechanism for position maintenance, and includes the counterweight for spontaneous lowering. This multi-functionality eliminates the need for separate dedicated components, reducing complexity.
3Device complexity
If the locking mechanism is located on the pin attaching the side rail to the bed, then the locking function is integrated, but the operator must use fingers to manipulate the lock which is not simple or fast
Solution Approach 1:
The patent introduces an intermediary lever arm that connects the operator's hand to the locking mechanism. This lever arm allows the operator to apply force with their hand rather than using fingers directly on the locking mechanism, making the operation simpler and faster while still achieving the same locking function.
Solution Approach 2:
The locking mechanism is extended along the side rail in the vertical dimension, moving the locking element away from the horizontal pin location. This dimensional change allows for a larger operating surface that can be manipulated with the entire hand rather than just fingers, improving ease of operation.
4Device complexity
If buttons are used as locking mechanism, then the locking function is simplified, but enormous friction occurs between the button and locking element causing malfunction
Solution Approach 1:
The patent replaces the button-based friction-dependent locking mechanism with a lever-based mechanical advantage system. This substitution eliminates the enormous friction problem by using a different mechanical principle where force is applied through leverage rather than direct friction between contact surfaces.
Solution Approach 2:
The lever arm acts as an intermediary that transfers the operator's force to the locking element through a rotational pivot point. This intermediary mechanism allows for controlled engagement and disengagement of the locking element, preventing the friction-related malfunctions that occur with direct button-to-locking-element contact.
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
Enhances operator comfort and patient safety by ensuring the side rail remains securely locked in the raised position until intentionally lowered, reducing the risk of accidental movement and simplifying the operation process.
Implementation Method 1
A bed side rail design featuring a torsion spring in the rotational bearing
Implementation Method 2
a locking mechanism with a rotational actuating member and spring system that ensures the side rail remains locked
Implementation Method 3
using a combination of torque and friction to prevent spontaneous movement
Data Source
Figure 1
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AI summary
Side rail (2) of bed (1) comprising two side bars (5) fitted with a rotational bearing (4) at the bottom end for attachment to the frame of the bed (1), where the side bars (5) are connected by a top bar (6) at the top end to form a parallelogram. A locking mechanism (3) is located between one of the side bars (5) and the top bar (6) comprising a first member (11) firmly fixed to the side bar (5) and second member (12) firmly fixed to the top bar (6), where these members have a common axis (10) of rotation. One member comprises two notches (16, 17) and the second member a stop (13) to restrict the mutual rotational movement of the members. A latch (9) to keep the side rail (2) in the locked position is connected to the locking mechanism (3). In an alternative design, the cover member (12) can be connected to the side bar (5) and rotational member (11) on the top bar (6), and the locking mechanism adapted accordingly.