Pull-Down Bed Safety Mechanism to Prevent Leg Pinching During Closure
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Solution Overview
Problem
Existing pull down beds with movement mechanisms that synchronize the rotation of the bed frame and legs pose a safety risk during closure, as they can pinch or cut users' limbs if they accidentally place a limb along the rotation path of the legs, especially when an electric motor is used for closing.
Innovation Solution
Incorporating a safety mechanism with a control rod and an extendable safety member, such as a helical spring or axial damping device, that stops the leg's rotation when an obstacle is detected, preventing the scissors-like movement and keeping the leg in the open position if an obstruction is encountered during closure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a movement mechanism with a rigid rod is used to synchronize the rotation of the bed frame and legs, then the legs are constrained to rotate with the bed frame during opening and closing operations, but this creates a safety hazard where the leg can pinch or cut user limbs during the closing operation
Solution Approach 1:
The patent transforms the rigid, fixed-length control rod into a telescopic control rod with variable length. The control rod can extend and retract along its longitudinal axis, allowing it to dynamically adjust its length during the bed frame's rotation. This dynamic adjustment enables the leg to rotate independently when needed (safety) while still being guided by the control rod during normal operation, thus resolving the contradiction between safety and mechanism simplicity.
Solution Approach 2:
The telescopic control rod acts as an intermediary between the bed frame and the leg. Instead of directly rigidly connecting the two, the control rod provides a flexible connection that can adapt its length. This intermediary element allows the system to maintain controlled movement while preventing the dangerous pinching effect, as the control rod can extend to accommodate the leg's independent rotation when a limb is detected in the rotation path.
2Extent of automation
If an electric motor is used to automatically close the bed frame, then the closing operation is automated and convenient, but the safety risk of pinching or cutting limbs is increased due to the forced closing motion
Solution Approach 1:
The patent incorporates a safety sensor that detects the presence of limbs in the leg's rotation path. When a limb is detected, the sensor provides feedback to the control system, which then prevents the electric motor from activating or stops the closing operation. This feedback mechanism allows the system to maintain automatic closing functionality while eliminating the safety hazard by detecting and responding to obstructing limbs.
Solution Approach 2:
The safety mechanism performs preliminary detection before the closing operation begins. The sensor scans the rotation path of the leg to detect any limbs in advance. If a limb is detected, the system takes preliminary action to prevent the closing operation from starting, thereby avoiding the harmful pinching or cutting effect before it can occur.
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 safety mechanism ensures user safety by preventing the leg from closing into a position that could pinch or cut limbs, maintaining the leg in an open position when an obstacle is present, thus avoiding injury and allowing safe operation even with automatic closing systems.
Implementation Method 1
said safety member comprises an elastic mechanical member
Implementation Method 2
such as a helical spring
Implementation Method 3
axial damping device
Data Source
Figure 1
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Figure 3
AI summary
A pull down bed (1) comprising a cabinet (3), a bed frame (2) which is hinged to the cabinet (3) so as to rotate between a first vertical position and a second horizontal position, a pair of legs (11), each hinged on the bed frame (2) so as to be able to rotate between an operating position, in which the leg (11) is standing, and a rest position, in which the leg (11) is approximately coplanar with the bed frame (2), a movement mechanism (13) comprising a control rod (15) structured to rotate a leg (11) between the rest position and the operating position and in response to the rotation of the bed frame (2) between the first and the second positions. The movement mechanism (13) further comprises a safety member (15) which is structured to cooperate with the control rod (15) so that the rotation imparted by the control rod (15) to the leg (11) from the operating position to the rest position, in response to the rotation of the bed frame (2) from the second position to the first position, is stopped when the leg (11) is hindered in its rotation movement.