Flushing Tank Dosing Device Using Bellows Piston to Prevent Liquid Loss
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Solution Overview
Problem
Existing dosing devices for flushing tanks in sanitary fittings are not simple, effective, or reliable, often leading to service liquid contamination and wastage due to inefficiencies and malfunctions.
Innovation Solution
A dosing device utilizing a combination of a piston and expandable bellows, which operates within a flushing tank to accurately measure and deliver a preset dose of service liquid only during flushing, preventing contamination and wastage by using a non-return valve and a retaining system in the overflow pipe to hold the liquid until the next flush.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a dosing device uses a simple piston mechanism operated by water stream, then the device complexity is reduced, but service liquid loss and contamination occur due to incomplete dosing and residual liquid remaining in the chamber
Solution Approach 1:
The dosing chamber is divided into two distinct compartments: a first chamber for receiving service liquid from the reservoir and a second chamber for delivering the measured dose to the flushing stream. This segmentation allows complete transfer of service liquid without mixing zones where residues could remain, eliminating the source of contamination and loss.
Solution Approach 2:
A non-return valve is introduced as an intermediary component between the first and second chambers. This valve acts as a controlled gateway that permits service liquid to flow from the first chamber to the second chamber during dosing, then prevents any backflow. This intermediary mechanism ensures complete dosing without residues while maintaining system simplicity.
2Ease of operation
If the dosing chamber is continuously open to the reservoir for refilling, then the ease of operation is improved, but service liquid contamination occurs when the tank is not in use
Solution Approach 1:
The dosing chamber operates on a periodic cycle: during normal operation, the non-return valve opens to allow service liquid transfer; during idle periods, the valve remains closed to seal the chamber. This periodic action pattern enables automatic refilling when needed while preventing contamination during storage, resolving the contradiction between ease of operation and contamination prevention.
Solution Approach 2:
The non-return valve extracts the contaminating element (backflow pathway) from the system. By removing the possibility of reverse flow, the system achieves both automatic refilling capability and contamination prevention, as the valve selectively permits flow only in the desired direction during active dosing cycles.
3Reliability
If a non-return valve is added to prevent backflow and contamination, then the reliability is improved, but the device complexity increases
Solution Approach 1:
The non-return valve is designed as a passive, self-regulating component that automatically responds to pressure differential: it opens when water flow creates positive pressure from the reservoir side, and closes when pressure equalizes or reverses. This self-service mechanism provides reliable backflow prevention without requiring external control systems, actuators, or complex timing mechanisms, thus maintaining device simplicity while enhancing reliability.
4Ease of manufacture
If the piston is solely operated by water stream pressure, then the ease of manufacture is improved, but the measurement precision of service liquid dose is insufficient leading to wastage
Solution Approach 1:
The dosing chamber is pre-configured with a predetermined volume capacity that corresponds to the exact required dose. The non-return valve and chamber geometry are designed in advance to ensure that when the chamber fills from the reservoir, it automatically stops at the precise volume mark. This preliminary design of fixed geometry eliminates the need for complex active control systems, maintaining ease of manufacture while achieving precise dosing through passive volumetric measurement.
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
Ensures precise and complete delivery of the service liquid with no residual waste, enhancing the reliability and effectiveness of the dosing process while maintaining tank cleanliness.
Implementation Method 1
When the bellows 24 is filled with water and expands, the contact end 42 moves axially away from the root end 39
Implementation Method 2
a contact end 42, which cooperates in abutment with the head 34 of the piston 23 and in particular with the plate 36
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A dosing device (5) for dosing a service liquid in a water stream discharged from a flushing tank, comprises: a reservoir (21) for a service liquid; a dosing chamber (22) communicating with the reservoir (21) for receiving a dose of service liquid from the reservoir (21) through an opening (30); a movable piston (23) housed in the dosing chamber (22) and operated by an expandable bellows (24); a water supply pipe (25), connectable to a filling valve (3) of the tank (1) for feeding water to the bellows (24) so as to expand the bellows (24) and consequently move the piston (23) in the chamber and push service liquid from the dosing chamber (22) into a delivery pipe (26) of service liquid connectable to an overflow pipe (15) of the tank (1).