Bed that is movable from a low position to a high position with a load transfer assembly
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Solution Overview
Problem
Existing hi-low bed designs with linear actuators experience high actuator load at the beginning of the stroke and low load at the end, leading to inefficient mattress frame raising mechanisms.
Innovation Solution
A bed design incorporating a load transfer assembly with pivot arms and cam arms, featuring a nonlinear cam surface and orbital connections, which controls the actuator load curve to maintain a consistent and controlled load output, preventing mechanical damage and enhancing structural rigidity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a linear actuator is used to raise the mattress frame, then the mattress frame can be raised, but the actuator load is very high at the beginning of the stroke and relatively low at the end of the stroke
Solution Approach 1:
The patent employs a cam surface with a nonlinear curved profile instead of a linear guide. The cam surface is designed with specific curvature variations that transform the actuator's linear motion into a controlled rotational motion of the lift assembly. This curvature allows the actuator to maintain a relatively constant load throughout the stroke by adjusting the mechanical advantage at different positions, thereby resolving the contradiction between reliability and force.
Solution Approach 2:
The patent changes the geometric parameters of the cam surface profile to optimize the load distribution. By carefully selecting the cam surface curvature, radius, and other geometric parameters, the design achieves a more uniform actuator load curve. This parameter optimization allows the system to maintain reliable operation while reducing peak forces, directly addressing the technical contradiction.
2Reliability
If the actuator load is high at the beginning of the stroke, then the mattress frame can be lifted, but mechanical damage may occur
Solution Approach 1:
The cam surface design incorporates a gradual engagement profile at the beginning of the stroke that softly introduces the lift mechanism into operation. This preliminary cushioning effect prevents sudden high forces that could cause mechanical damage, while still achieving the necessary lifting function. The curved cam profile ensures that the actuator load builds up gradually rather than instantaneously.
Solution Approach 2:
The curved cam surface provides a smooth transition and load distribution that prevents sharp force peaks. The geometric curvature is specifically designed to limit maximum actuator load and distribute forces more evenly, thereby preventing mechanical damage while maintaining reliable lifting operation throughout the stroke.
3Reliability
If a load transfer assembly with cam surface is used, then the actuator load curve can be controlled, but the device complexity increases
Solution Approach 1:
The cam arm assembly serves multiple functions simultaneously: it acts as a load transfer mechanism, provides the cam surface for load curve control, guides the follower motion, and connects the actuator to the lift mechanism. This multi-functionality reduces the need for separate components, thereby limiting the increase in device complexity while achieving reliable load curve control.
Solution Approach 2:
The follower acts as an intermediary element that transfers motion and force between the cam surface and the pivot arm. This simple intermediary component enables complex load curve control without requiring elaborate mechanisms, thus achieving reliable actuator load control while minimizing the increase in overall device complexity.
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 controlled actuator load curve ensures a flat load output, preventing mechanical damage by automatically shutting off when maximum load is exceeded, and increases structural rigidity by distributing load evenly across the bed.
Implementation Method 1
The cam arm (or arms) is connected to the main frame. One end of the pivot arm (or arms) is pivotally connected to the support frame. The other end of the pivot arm is pivotally connected to the actuator... The cam surface can be an upper surface of a slot... The cam surface, as well as the orbital location of the pivotal connection of the end of the actuator and the cross member (or pivot arm end) and the pivotal connection between the pivot arm and the support frame determine the actuator load curve
Implementation Method 2
The pivot arm has one end pivotally connected to support frame. This pivot location is a fulcrum. Two other loads (one from the actuator and one from the main frame) will act on the same aside of the fulcrum. The second end of the pivot arm is connected to the actuator... The point of connection with the actuator orbits about fulcrum during the actuator stroke
Data Source
AI summary
A bed that is movable from a low position to a high position with a tailored actuator load output is provided. The bed has a main frame between two bed ends. An end lift assembly is provided on each end to raise and lower the bed. Each end lift assembly has a wheel frame, a wheel assembly, a support frame, a load transfer assembly and an actuator. The load transfer assembly has one or more pivot arms and one or more cam arms. The cam arm (or arms) is connected to the main frame. One end of the pivot arm (or arms) is pivotally connected to the support frame. The other end of the pivot arm is pivotally connected to the actuator in a single arm embodiment and are connected to a cross member that is pivotally connected to the actuator in a multiple pivot arm embodiment.