Foam Pump Lost-Motion Linkage for Priming and Adjustable Output
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Solution Overview
Problem
Foam pumps often experience issues with air trapped in the liquid piston, leading to inconsistent output and failure to prime when short stroked, and they typically have a constant volume output that cannot be easily adjusted without replacing the pump.
Innovation Solution
The design incorporates a lost motion linkage and adjustable output mechanism, featuring a liquid piston and air piston linked to an actuator, allowing for adjustable dosages and preventing air from entering the liquid piston during short strokes, with adjustable configurations for varying output percentages and the option for lost motion or no lost motion operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a blocking plate is added to prevent full stroke movement, then short stroking is prevented, but the pump will not prime because air bubbles remain in the liquid piston
Solution Approach 1:
The pump chamber is segmented into an air chamber and a liquid chamber separated by a T-seal on the piston. This segmentation prevents air bubbles from contaminating the liquid chamber during short stroke operations, allowing the pump to maintain priming capability while accepting blocked actuator movement.
Solution Approach 2:
The T-seal acts as an intermediary element between the air chamber and liquid chamber. It allows the piston to move and compress air in the air chamber while preventing air from entering the liquid chamber, thus enabling short stroke operation without compromising priming.
2Reliability
If the actuator stroke is made greater than the piston stroke, then short stroking is prevented, but device complexity increases due to lost motion linkage requirements
Solution Approach 1:
Instead of making the piston stroke longer to match the actuator, the solution inverts the approach by allowing the actuator stroke to be longer and using a T-seal mechanism to handle the extra movement. This simplifies the linkage by eliminating the need for complex lost motion mechanisms.
3Ease of manufacture
If foam pumps are designed with constant volume output, then pump design is simplified, but adaptability to different dosage requirements is reduced
Solution Approach 1:
The pump incorporates an adjustable T-seal position mechanism that allows dynamic adjustment of the liquid chamber volume. By moving the T-seal to different positions on the piston, the pump can deliver variable dosages while maintaining a relatively simple basic pump design.
Solution Approach 2:
The invention changes the geometric parameter of the liquid chamber volume by adjusting the T-seal position. This allows the same pump hardware to deliver different dosages by simply changing the effective volume parameter, without requiring different pump designs.
Data Source
AI summary
Embodiments of lost motion foam pumps are disclosed herein. One exemplary embodiment includes a liquid chamber, a liquid piston movable in the liquid chamber, an air chamber and an air piston movable in the air chamber. The air piston is linked to the liquid piston. A connector is linked to the air piston or the liquid piston. The connector includes an engagement member for connecting to an actuator of a foam dispenser. Movement of the actuator in a first direction moves the liquid and air pistons to contract the liquid chamber and the air chamber. Movement of the actuator a first distance in a second direction does not move the liquid piston or the air piston; however, continued movement of the actuator a second distance in the second direction moves the liquid piston and the air piston and expands the liquid and air chambers.