Actuator Lock Ring Mechanism for Stable Piston Rod Restriction
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Solution Overview
Problem
Conventional actuators for automotive safety equipment face challenges in stabilizing the backward movement restriction of piston rods and adjusting bending rigidity to effectively absorb kinetic energy, leading to potential locking failures and difficulties in kinetic energy absorption adjustments.
Innovation Solution
The actuator design incorporates a lock mechanism with an annular lock ring and a locking stepped portion, where the lock ring is accommodated in an accommodating groove on the piston portion and expands to restrict backward movement by engaging with the locking and restricting surfaces, allowing for stable locking and easy adjustment of bending rigidity without altering the piston or cylinder dimensions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the accommodating groove and fitting groove are made into taper surfaces that diametrically expand upwards, then the C ring can be easily inserted into the fitting groove, but the C ring cannot be effectively restricted from diametrically expanding and popping out of the fitting groove
Solution Approach 1:
The groove surfaces are designed with asymmetric taper angles: the accommodating groove has a larger taper angle (α1) while the fitting groove has a smaller taper angle (α2), where α1 > α2. This asymmetric configuration allows the C ring to be easily inserted into the fitting groove through the accommodating groove, while the smaller taper angle of the fitting groove effectively restricts the C ring from diametrically expanding and popping out, thereby resolving the contradiction between insertion ease and locking stability.
Solution Approach 2:
Different portions of the groove structure are assigned different functional qualities: the accommodating groove is designed with a larger taper angle to facilitate C ring insertion and movement, while the fitting groove is designed with a smaller taper angle to provide effective locking. This local differentiation of groove characteristics allows each portion to optimize its specific function, resolving the contradiction between ease of operation and reliability.
2Ease of operation
If the piston rod is made to slide on the inner circumferential surface of the cylinder along the full length, then the piston rod can be smoothly moved, but the C ring cannot be effectively positioned and locked
Solution Approach 1:
The sliding surface is segmented into two distinct zones: a first sliding surface along the full length of the cylinder for smooth piston rod movement, and a second sliding surface at the distal end with a smaller diameter that positions the C ring. This segmentation allows the piston rod to move smoothly along most of its行程 while effectively positioning and locking the C ring at the distal end, resolving the contradiction between movement smoothness and locking effectiveness.
Solution Approach 2:
The locking mechanism utilizes a dimensional change by creating a second sliding surface with a smaller diameter than the main cylinder bore. This dimensional variation at the distal end creates a positioning effect that enables effective C ring locking, while the majority of the sliding surface maintains the original diameter for smooth movement, thus resolving the contradiction through dimensional differentiation.
3Adaptability or versatility
If the outside diametrical dimension of the piston rod is changed to adjust bending rigidity, then the kinetic energy absorption can be adjusted, but the cylinder inside diameter must also be changed
Solution Approach 1:
The piston rod is segmented into functionally distinct portions: a main body portion that interfaces with the cylinder's full-length sliding surface, and a distal end portion with a smaller outside diametrical dimension that slides on the second sliding surface. This segmentation allows independent adjustment of the distal end portion's dimensions to modify bending rigidity and kinetic energy absorption characteristics without requiring changes to the cylinder's inside diameter, thereby resolving the contradiction between adaptability and device complexity.
Solution Approach 2:
The piston rod exhibits local quality differentiation where the distal end portion has different dimensional characteristics (smaller outside diameter) compared to the main body portion. This local variation enables adjustment of bending rigidity through modification of only the distal end portion, without affecting the overall cylinder-piston rod interface dimensions, thus resolving the contradiction between adaptability and 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
This configuration ensures stable restriction of backward piston rod movement and facilitates easy adjustment of bending rigidity, enhancing the actuator's ability to absorb kinetic energy effectively while maintaining a smooth operation with reduced frictional resistance.
Implementation Method 1
a lock ring which is contracted diametrically to be accommodated in an accommodating groove formed on the outer circumferential surface of the piston portion along a circumferential direction in a state where the piston rod has moved forwards, and is made of an elastically deformable wire material having a circular cross section
Implementation Method 2
maintaining a smooth operation with reduced frictional resistance
Implementation Method 3
the support rod portion is disposed so as to be bent and plastically deformed when the receiving member receives the object to be protected after the support rod portion has moved forwards so as to absorb kinetic energy of the object to be protected
Data Source
AI summary
When activated, an actuator causes a piston rod in a cylinder to move forwards so as to support a receiving member for receiving an object to be protected. A lock mechanism for restricting a backward movement of the piston rod includes a lock ring which is accommodated in an accommodating groove on a piston portion and a locking stepped portion on the cylinder side. The locking stepped portion includes a locking and restricting surface and an outer circumferential restricting surface. A taper restricting surface in the accommodating groove on the piston portion is brought into abutment with an inner surface on a forward moving side of the lock ring which is being diametrically expanded as a result of the piston rod having moved forwards and is in abutment with the locking and restricting surface and the outer circumferential restricting surface of the locking stepped portion, whereby the backward movement of the piston rod is restricted by making use of the lock ring which is restricted in the locking stepped portion.