Pinch Valve Control Path for Linear Flow and Pressure
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Solution Overview
Problem
Pinch valves typically operate only in fully open or fully closed positions, lacking the ability to control flow and pressure proportionally between these states, which is desirable in certain applications for precision and contamination prevention.
Innovation Solution
A proportionally controlled pinch valve system that includes a drive unit, position sensor, and control module, allowing the pinch head to move along a curved operational path for linear flow or pressure changes, and optionally featuring a 'fail safe' spring for enhanced control, using a pneumatic cylinder and position sensors to manage movement and pressure effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a traditional pinch valve operates only in fully open or fully closed positions, then the structure is simple and reliable, but the ability to control flow and pressure proportionally is lost
Solution Approach 1:
The pinch valve transitions from a static two-position system to a dynamic proportional control system. The drive unit can now operate at multiple positions along a curved operational path, enabling continuous adjustment of flow and pressure rather than just fully open or fully closed states.
Solution Approach 2:
A position sensor is integrated into the drive unit to detect its position along the operational path. This feedback mechanism allows the control module to precisely control the drive unit's position, enabling accurate proportional flow and pressure control while compensating for variations in the curved operational path.
2Manufacturing precision
If the pinch head moves along a curved operational path to achieve linear flow change, then proportional control is improved, but the control system complexity increases
Solution Approach 1:
The operational path of the drive unit is designed as a curve rather than a straight line. This curved path compensates for the non-linear relationship between pinch head position and flow rate, enabling linear flow change despite the mechanical constraints of the pinch valve system.
Solution Approach 2:
The control module uses a pre-set or tuned program that adjusts control parameters along the curved operational path. By changing the relationship between control input and drive unit position, the system achieves linear flow and pressure control despite the curved mechanical path.
3Reliability
If a fail safe spring is added to the pneumatic cylinder, then safety is improved, but the device complexity and force requirements increase
Solution Approach 1:
A fail safe spring is pre-installed in the pneumatic cylinder to provide automatic failure protection. The spring is positioned to engage when pneumatic pressure is lost, automatically returning the pinch head to a safe position (typically fully open) without requiring external power or control systems.
Solution Approach 2:
The fail safe spring acts as a counterbalancing force to the pneumatic cylinder's operating forces. The spring is calibrated to provide the necessary force to overcome the pneumatic pressure and return the valve to its fail-safe position, effectively counteracting the normal operating forces when needed.
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 precise, proportional control of flow and pressure changes along the operational path, ensuring linear changes and predictable pinch head movement, even against additional forces, enhancing application-specific performance and safety by preventing contamination.
Implementation Method 1
a position sensor that is in operative communication with the drive unit and that detects positioning of the drive unit
Implementation Method 2
the pinch valve comprising a pneumatic pinch valve in operative communication with a pneumatic cylinder and a pinch head
Data Source
Figure 1
Figure 2
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AI summary
The effect on the fluid flowing through tubing that is engaged by a pinch valve head between fully open and fully closed is considered, determined and used to achieve pinch valve operation that is linear in flow change and/or linear in pressure change along the closing path and/or opening path through the tubing. The pinch valves can include a normally closed port that opens when the system experiences a shut-down condition.