Push-Pull Control with Roller Pin Rotational Assist
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Solution Overview
Problem
Existing push-pull controls, such as the Standard Vernier Control, face limitations in distance traveled using rotational input, require a user-operated release for switching between rotational and linear inputs, and can experience 'ratchety' motion and jamming issues, which can be critical in applications like aircraft throttle control.
Innovation Solution
A push-pull control design utilizing an elongate push rod, a base, and a rotational assist cartridge with roller pins and pin cups that allow for both linear and rotational inputs to create linear output without a user-operated release, using a rotational assist cartridge to adjust forces between the roller pins and the push rod for seamless switching between input types.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a Standard Vernier Control uses rotational input to move the push rod, then the control can achieve fine positioning, but the distance traveled is limited by the length of the helical surface
Solution Approach 1:
The system dynamically switches between two input modes (rotational and linear) depending on the desired operation. The ball member can engage with the helical surface for rotational input or disengage to allow linear input, making the control system adaptable to different operational requirements rather than being fixed in one mode.
Solution Approach 2:
The push rod and control mechanism are designed to accept both rotational and linear inputs, making the system multi-functional. The same push rod structure serves both precision positioning (rotational) and large-distance movement (linear) functions, eliminating the need for separate mechanisms for each type of input.
2Ease of operation
If the button is pressed to allow linear input in a Standard Vernier Control, then the push rod can move freely, but the motion becomes 'ratchety' as the ball contacts each thread of the helical surface
Solution Approach 1:
The ball member is extracted from the helical engagement path during linear input operations. By pressing the button, the ball is moved out of engagement with the helical surface, removing the source of ratchety motion and allowing smooth linear movement of the push rod without interference from the threading.
Solution Approach 2:
Before linear input is applied, the button is pressed to preliminarily disengage the ball from the helical surface. This preliminary action prevents the ball from contacting the threads during subsequent linear movement, thereby preventing ratchety motion before it can occur.
3Adaptability or versatility
If the ball is not completely released from the helical surface in a Standard Vernier Control, then rotational input can still be used, but the push rod movement is restricted and may jam
Solution Approach 1:
The mechanical engagement between the ball and helical surface is replaced with a controlled disengagement mechanism. The button acts as a release mechanism that completely separates the ball from the helical path, replacing the ambiguous partial engagement state with a clear engaged/disengaged binary state that prevents jamming.
Solution Approach 2:
The button mechanism provides beforehand cushioning by ensuring complete release of the ball from the helical surface before linear input is applied. This prevents the problematic intermediate state where the ball partially contacts the threads, which could cause jamming or unreliable operation.
4Reliability
If a friction nut is used to compress packing around the push rod, then the push rod can remain in a desired location, but rotational input has no effect and structure is needed to restrict rotation
Solution Approach 1:
The system dynamically switches between position holding (friction engaged) and rotational responsiveness (friction disengaged) modes. The button mechanism allows the user to temporarily overcome the friction hold, press the button to disengage the ball from the helical surface, and then apply linear input to move the push rod, providing both position stability and operational flexibility.
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
Enables smooth and efficient linear output without the need for a user-operated release, reducing the risk of jamming and 'ratchety' motion, and allowing for larger distance movement with rotational input, enhancing safety and performance in applications like aircraft throttle control.
Implementation Method 1
The roller pin has a smooth outer surface and is rotatable about the roller pin center axis... at least one point of the roller pin outer surface contacts the push rod outer surface
Implementation Method 2
The rotational assist cartridge positions the roller pins such that... the roller pin center axis is angularly offset and non-intersecting with the push rod center axis
Data Source
AI summary
Push-pull controls utilizing linear and rotational inputs to create linear output are disclosed. One control includes an elongate push rod and a roller pin. The rod has an outer surface, a generally circular cross-section perimeter, a center axis, a proximal end with a user input, and a distal end configured to directly or indirectly interact with an apparatus to be controlled. The rod is rotatable and slidable along the rod axis. The roller pin has a center axis and an outer surface that contacts the push rod outer surface. The roller pin center axis is angularly offset from and non-intersecting with the push rod center axis. The amount of angular offset is greater than zero degrees.