Dual-Bellows Fluid Pump for Long Stroke and Tight Sealing
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Solution Overview
Problem
Existing fluid pumps with bellows as a restoring means face limitations in manufacturing due to high production costs for longer strokes and uneven compression, leading to insufficient sealing and tightness, especially when using bellows with a large compression stroke.
Innovation Solution
The pump design incorporates two independent bellows arranged one above the other, each with controlled surface angles and thread-like bulges, allowing for a longer pumping stroke and improved sealing through nested surfaces and flexible engagement with the pump head and piston, enhancing the sealability between the bellows and piston.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If a single bellows is used to provide return stroke force, then the pump structure is simple, but the compression stroke length is limited and manufacturing costs increase significantly for longer strokes
Solution Approach 1:
The single bellows is divided into two separate bellows (first bellows and second bellows) arranged in series. Each bellows contributes to the total compression stroke length, allowing the pump to achieve a longer overall stroke without requiring an excessively long single bellows that would be costly to manufacture. The first bellows is engaged directly by the pump head while the second bellows is engaged by the first bellows, creating a segmented force transmission path.
2Productivity
If a bellows is compressed with large stroke, then the pumping capacity increases, but the wrapping behavior becomes uneven over circumference and height
Solution Approach 1:
By segmenting the compression function across two bellows, each bellows experiences a more manageable compression range that maintains uniform wrapping behavior. The first bellows handles the initial compression from the pump head, while the second bellows handles the subsequent compression, distributing the deformation evenly and preventing the uneven wrapping that occurs in single bellows with large strokes.
3Reliability
If the piston lips engage the pump chamber body to seal the pump chamber, then the sealing is basic, but the tightness is insufficient especially with large bellows compression
Solution Approach 1:
The bellows are configured to act as an intermediary sealing element between the piston and the pump chamber body. The side wall of the bellows engages with the pump chamber body to provide an additional sealing interface, supplementing the piston lip seals. This intermediary sealing mechanism enhances tightness without requiring a complete redesign of the piston sealing structure.
4Force
If one bellows is engaged directly by the pump head and another by the first bellows, then the return stroke force is distributed, but the force transmission path becomes more complex
Solution Approach 1:
The two bellows are merged into a series configuration where the first bellows and second bellows work together as a unified restoring means. The force transmission path, while extended, follows a logical sequence: pump head compresses first bellows, which in turn compresses second bellows, creating a combined restoring force that pushes the pump head upward. This merging approach distributes the force while maintaining a relatively simple force transmission architecture.
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 enables a longer compression stroke with improved sealability and tightness, reducing manufacturing costs and ensuring effective fluid dispensing without leakage, even under varying operational conditions.
Implementation Method 1
a first bellows and a second bellows, each of the bellows being an independent bellow... folded up, when moving the pump head into the lower end position, by exerting a compression force on the pump head
Data Source
Figure 1~2
Figure 3
Figure 4~4a
AI summary
The invention is related to a pump (1) for dispensing a fluid, with a pump head (2), a piston body (15) with a piston, a pump chamber (13) limited by a pump chamber body (14), an inlet valve (12) and an outlet valve (16), the piston being moveable by respective movement of the pump head (2) between an upper starting position and a lower end position, wherein a return stroke force for a return stroke from the lower end position into the upper starting position is provided by a bellows (18), wherein further two bellows are arranged one above the other, a first bellows and a second bellows, each of the bellows (18) is folded up, when moving the pump head (2) into the lower end position, by exerting a compression force on the pump head (2), the first bellows receiving the compression force by direct engagement with the pump head (2), the second bellows receiving the compression force only by engagement with the first bellows.