Force Control Strut with Segmented Damping for Consistent Closing Speed
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Solution Overview
Problem
Existing elongated struts with compression springs fail to effectively control and selectively dampen the motion of movable elements, such as vehicle hoods or trunk lids, leading to varying closing speeds throughout the movement stroke due to design limitations in matching load offsets.
Innovation Solution
Incorporating a damper mechanism into a standard compression spring strut, allowing controlled force application during movement by using a plunger and passageway system within the rod, which engages a bottom plug to provide damping only during specific phases of the stroke, and optionally using a check valve to differentiate damping forces between extension and retraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a compression spring strut is used to support a movable element, then the load can be balanced, but the closing speed varies throughout the movement stroke due to inability to selectively dampen motion
Solution Approach 1:
The strut is segmented into distinct functional zones: an undamped first portion allowing free movement, and a damped second portion providing controlled resistance. This segmentation allows different motion characteristics in different stroke regions, enabling consistent closing speed while maintaining load balancing capabilities.
Solution Approach 2:
Damping is applied locally only to the second portion of the strut rather than uniformly throughout. The damping characteristic is introduced selectively in the region where motion control is needed, while the first portion remains undamped to allow natural spring action and load balancing.
2Speed
If damping is applied throughout the entire strut, then motion can be controlled, but the complexity of the device increases
Solution Approach 1:
The damping mechanism is segmented to operate only in the second portion of the strut stroke. The first portion remains a simple tubular structure without damping components, reducing overall device complexity while still providing motion control where needed.
Solution Approach 2:
Damping is applied partially rather than fully throughout the entire stroke. By providing damping only in the second portion where motion control is most beneficial, the device achieves adequate motion control without the complexity and cost of damping the entire strut length.
3Ease of manufacture
If the rod is made solid to simplify manufacturing, then manufacturing is easier, but an internal damper mechanism cannot be incorporated
Solution Approach 1:
The damping mechanism is nested within the hollow rod structure. The rod serves as a container housing the damper assembly, allowing the damping function to be integrated without requiring a completely different rod manufacturing approach. The hollow structure naturally accommodates the nested damper components.
Solution Approach 2:
The hollow rod structure serves multiple functions: it provides structural support, contains the damping mechanism, and guides the plunger movement. This multi-functionality reduces the need for separate components and simplifies manufacturing compared to solid rod designs that would require separate damping assemblies.
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 solution enables controlled force and motion management during the movement of movable elements, ensuring consistent speed and increased versatility, while being economical and easier to manufacture compared to existing solutions.
Implementation Method 1
A coil spring is positioned inside the housing between the rod member and one end of the housing so the spring forces the rod member outwardly
Implementation Method 2
The plunger of the damper mechanism is movable outwardly from an end of the rod facing inside the elongated housing to create a controlled force dampening movement of the operating rod in the housing
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
A force control strut comprising an elongated housing having a straight guide tube with an inner surface, a rod member having an inner end reciprocally movable along the guide tube and an outer end extending outwardly from the housing, a guide member secured into the first end of the housing to form a bushing allowing reciprocation of the rod member between a retracted position and an extended position and a bottom plug fixed to the second end of the housing. A guide piston is secured to the inner end of the rod and is slidable along the inner surface of the housing. A coil spring is located between the piston and one end of the housing to bias the rod in a given direction in the housing. There is a damper mechanism combined with the movable rod and including a plunger reciprocally mounted in an elongated force controlling passageway inside the rod. The plunger is movable outwardly from the rod and has a distal end engageable with the bottom plug to force the plunger intro the force controlling passageway to dampen movement of the rod in the housing.