Dual Linear Actuator With Manual Emergency Bed Lowering
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Solution Overview
Problem
Existing electrically driven linear dual actuators for beds face issues with emergency lowering during power failures or electrical errors, as previous solutions either discharge the emergency power battery or require complex mechanical interventions, making it difficult to safely lower the back and leg rest sections.
Innovation Solution
A dual actuator design with a rotating element accessible from the outer side of the housing, featuring a recess for tool insertion, allows for manual emergency lowering using an Allen key or electric screwdriver, decoupling the drive mechanism to enable safe manual operation of the back and leg rest sections without relying on the power supply.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a 9V battery is used as emergency power battery to lower the back rest and leg rest section, then the emergency lowering function is provided, but the battery is difficult to replace as it is located between the upper side of the dual actuator and the underside of the slatted frame
Solution Approach 1:
The battery compartment is extracted as a separate accessible unit on the dual actuator housing, allowing the battery to be removed and replaced without disassembling the actuator or accessing internal components. This resolves the contradiction by providing both emergency lowering functionality and easy battery replacement access.
2Extent of automation
If the emergency power battery is used to power the mains cut-off relay, then the relay can connect the transformer-based power supply to mains, but the battery becomes partially discharged and cannot lower the back rest and leg rest section in case of mains power failure
Solution Approach 1:
The power management system is segmented into two independent power sources: a rechargeable battery for the mains cut-off relay and a disposable 9V battery for emergency lowering. This segmentation resolves the contradiction by ensuring that the emergency lowering function has its own dedicated power source that cannot be depleted by relay operations.
Solution Approach 2:
A capacitor is introduced as an intermediary energy storage element that charges during normal operation and provides power to the mains cut-off relay when needed, eliminating the need to use the emergency power battery for relay operation. This resolves the contradiction by protecting the emergency battery from discharge while maintaining automated relay functionality.
3Ease of operation
If a mechanical emergency lowering solution with a cam and clutch is used, then the back rest or foot rest can be lowered by hand during power failure, but the device complexity increases
Solution Approach 1:
The complex mechanical cam and clutch system is replaced with a simple electrical solution: a 9V battery-powered motor that directly drives the lowering mechanism. This substitution resolves the contradiction by providing easy manual operation through a simple battery-motor system rather than complex mechanical components.
4Reliability
If the connection for tools is made larger to transfer larger torque, then the emergency lowering becomes more reliable, but the connection becomes more exposed to overload
Solution Approach 1:
The system performs preliminary action by automatically lowering the bed sections during normal operation before an emergency occurs, positioning the sections in a safe state and reducing the torque demand on the emergency connection. This resolves the contradiction by preparing the system in advance, making the emergency connection smaller and less exposed to overload while maintaining reliable emergency lowering capability.
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
Linear dual actuator for lying or sitting furniture having at least two sections (2,3), which with one end is rotatably embedded in the article of furniture and where each section (2,3) with an arm (5,7) secured to a pivot shaft (4,6) can be adjusted by means of the linear dual actuator. The dual actuator comprises a housing (8) with a drive at each end, which comprises an electric motor (11), which through a transmission (12) is in driving connection with a spindle (13). On the spindle (13) is arranged an activation element (14) with a spindle nut in engagement with the spindle (13), where the activation element (14) can be brought into engagement with the arm (5,7) for adjusting the sections (2,3). In case of power failure there is the problem that the back rest and leg rest section cannot be lowered to a plane level, which can make the bed uncomfortable or completely impossible to sleep in. This problem is solved in that a rotating element in the drives comprises a connection (21), which is accessible from the outer side of the housing (8) for connecting a tool, e.g. an Allen key (22) for driving the respective drives for the back rest and leg rest section (2,3) for lowering of these to a horizontal position.