Asymmetric Cam Pump for Viscous Mastic Pressure Stability
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Solution Overview
Problem
Conventional pumps for thick, viscous materials like mastic face challenges in maintaining high pressure over long distances and at low flow rates, leading to issues such as fluid thickening or solidification and the need for numerous pumps and storage vessels close to application points, as well as difficulty in operating at low speeds without pressure drop.
Innovation Solution
A positive displacement pump with a variable speed electric motor and cam arrangement that drives multiple pistons out of phase, allowing more than half of the pistons to pump fluid in the second direction, reducing pressure drops and enabling operation at low speeds while maintaining high pressure, even when the fluid quantity is small.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If conventional pumps are used to pump viscous mastic materials, then the pump can deliver fluid, but the circuit must be short and the pump must be located close to the application station
Solution Approach 1:
The patent employs a dynamic cam mechanism that allows the piston to spend more time in the pumping stroke (second direction) than in the drawing stroke (first direction). This asymmetric timing dynamic enables the pump to maintain high pressure over longer circuit lengths by extending the pressure application duration, thereby resolving the contradiction between circuit length and pressure maintenance reliability.
2Speed
If the pump operates at low speeds for small amounts of mastic, then energy consumption is reduced, but pressure drops occur
Solution Approach 1:
The asymmetric cam mechanism creates a dynamic imbalance where the piston remains in the pressure-generating pumping stroke for a longer duration even at reduced speeds. This dynamic characteristic allows the pump to maintain outlet pressure at low operating speeds, resolving the contradiction between speed reduction and pressure maintenance.
3Force
If conventional cam arrangements drive pistons with equal time in both directions, then mechanical balance is achieved, but pressure drops occur during piston direction changes
Solution Approach 1:
The patent introduces an asymmetric dynamic cam mechanism where the piston spending more time in the pumping stroke creates a deliberate mechanical imbalance. This dynamic imbalance is designed to overlap the pumping strokes of multiple pistons, ensuring continuous pressure generation and eliminating pressure drops during direction changes, thereby resolving the contradiction between mechanical balance and pressure stability.
4Reliability
If multiple pumps are installed close to application points to ensure pressure, then pressure reliability is improved, but device complexity increases
Solution Approach 1:
The asymmetric cam mechanism enables a single pump to perform multiple functions: it can maintain high pressure over long distances, operate efficiently at variable speeds, and provide stable pressure without requiring multiple units. This multi-functional capability resolves the contradiction between pressure reliability and device complexity by making one pump replace multiple pumps.
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 allows for efficient pumping of viscous materials over longer distances with consistent high pressure and reduced mechanical stress on the cam, enabling a single pump to handle a wide range of flow rates and reducing the need for multiple pumps and storage vessels.
Implementation Method 1
A variable speed electric motor is drivingly coupled to a cam arrangement providing a reciprocating drive to the pistons
Data Source
AI summary
A positive displacement pump for pumping a fluid mastic comprises a plurality of cylinders each having a piston arranged for reciprocal motion within the cylinder. Movement of the piston in a first direction draws the fluid into the cylinder and movement in a second, opposite direction pumps the fluid out of the cylinder. A variable speed electric motor is drivingly coupled to a cam arrangement providing a reciprocating drive to the pistons. The cam arrangement comprises cams shaped and arranged to drive each piston in the first direction over less than half of a rotational cycle and to drive each piston in the second direction over the remainder of the rotational cycle. The cams are arranged to drive the pistons out of phase with one another.