Dual Spring Overfill Limiter for Diaphragm Pump
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing diaphragm pumps face issues with overfill conditions leading to diaphragm failure due to pressure spikes, and previous solutions either leak at high pressures or cause excessive stress with rigid travel limiters, while also requiring vent grooves or complex modifications.
Innovation Solution
A hydraulically driven diaphragm pump with an overfill limit assembly utilizing two springs of different spring constants, where a softer first spring compresses during startup and a stiffer second spring prevents overfill by covering the valve port, eliminating the need for a vent groove and minimizing stress on the diaphragm.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a stiffer spring is used to prevent overfilling, then overfill protection is improved, but pressure spikes occur that can cause diaphragm failure
Solution Approach 1:
The spring system is segmented into two distinct springs (first spring with lower spring constant and second spring with higher spring constant) that operate in sequence. The softer first spring handles normal compression during startup and operation, while the stiffer second spring engages only when the first spring is fully compressed and overfilling occurs, providing protection without transmitting excessive pressure spikes to the diaphragm.
2Strength
If a soft spring is used to avoid pressure spikes, then diaphragm stress is reduced, but the system cannot effectively prevent overfilling
Solution Approach 1:
The spring system is segmented into two distinct springs (first spring with lower spring constant and second spring with higher spring constant) that operate in sequence. The softer first spring handles normal compression during startup and operation, while the stiffer second spring engages only when the first spring is fully compressed and overfilling occurs, providing protection without transmitting excessive pressure spikes to the diaphragm.
Solution Approach 2:
The spring system dynamically transitions from the first spring supporting the load during normal operation to the second spring engaging when the first spring is fully compressed. This dynamic switching allows the system to adapt its stiffness characteristics based on operating conditions, providing both comfort during normal operation and protection during overfill events.
3Reliability
If a travel limiter is used to prevent overfilling, then overfill protection is improved, but pressure rises sharply causing stress on the diaphragm
Solution Approach 1:
The first spring with lower spring constant acts as a cushion that compresses beforehand during normal operation and startup. When overfilling occurs, this pre-compression absorbs the initial pressure surge, and the gradual engagement of the second spring provides a controlled pressure increase rather than a sharp spike, protecting the diaphragm while still preventing overfill.
4Ease of operation
If a vent groove is added to allow priming, then priming capability is improved, but the system becomes more complex and may leak at high pressures
Solution Approach 1:
The invention extracts the priming function from the cylinder structure by eliminating the need for vent grooves. Instead, priming is achieved through the spring-loaded valve spool mechanism that automatically opens the valve port during startup when the first spring compresses, allowing hydraulic fluid to enter the transfer chamber without modifying the cylinder.
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 effectively prevents overfilling without pressure spikes, allows oil priming without a vent groove, and reduces stress on the diaphragm, enhancing reliability and ease of manufacturing while maintaining low pressure drop across the diaphragm.
Implementation Method 1
A first spring in the piston inner chamber is positioned intermediate the valve spool and the spacer and has a first spring constant. Movement of the first spring is limited by a spacer slidably mounted in the piston inner chamber. A second spring is also positioned in the piston inner chamber intermediate the end of the piston inner chamber and the spacer. The second spring has a second spring constant greater than the first spring constant. Therefore, the first spring compresses first and then the second spring compresses.
Implementation Method 2
A transfer chamber is adapted to contain hydraulic fluid deflecting the diaphragm and is in fluid communication with a fluid reservoir
Implementation Method 3
A cylinder is contained in the pump housing and includes a piston sliding in a reciprocating motion and pumping hydraulic fluid
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A diaphragm pump includes a housing having a pumping chamber containing fluid to be pumped. The pump has a transfer chamber adapted to contain hydraulic fluid, and a hydraulic fluid reservoir in fluid communication with the transfer chamber. The pump housing forms a cylinder with a piston sliding in a reciprocating motion in the cylinder, the piston defining a piston inner chamber. A valve leads to the piston inner chamber with a valve spool slidably mounted in the piston inner chamber to cover the valve in a first position and uncover the valve in a second position. A diaphragm connects to the valve spool by a plunger. An overfill limiter includes a spacer slidably mounted in the piston inner chamber. A first spring in the piston inner chamber is intermediate the valve spool and the spacer. A second spring is in the piston chamber intermediate the end of the piston inner chamber and the spacer, the second spring having a second spring constant greater than the spring constant of the first spring.