Combination Valve Sealing Geometry for Backflow Pressure Control
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Solution Overview
Problem
Existing combination valves for water heaters face issues with the annular gasket blowing off due to water pressure and wear, and fail to meet stringent sealing requirements, particularly in the non-return valve function, leading to potential backflow and safety concerns.
Innovation Solution
The improved combination valve features a stopcock and non-return valve with separate sealing surfaces, where the non-return valve piston has a cap-shaped gasket with a conical, rounded edge and a radially configured groove, and a conical seat in the valve housing, providing a secure seal and reducing the sealing circumference to meet more stringent overpressure requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the annular gasket is arranged on the non-return valve piston to seal against water pressure, then the valve provides sealing function, but the gasket blows off due to water penetrating under it and pressure prising it out of its groove
Solution Approach 1:
The gasket is pre-installed in a groove on the non-return valve piston with its open end facing away from the flow direction. This preliminary positioning prevents water from penetrating under the gasket during operation, eliminating the blow-off problem while maintaining reliable sealing function.
2Reliability
If a lip is added to the gasket to seal against the piston in non-return closing position, then sealing is improved, but the lip bends radially outwardly under pressure and debris collects in the gap, deteriorating sealing function
Solution Approach 1:
The problematic lip structure is completely removed from the gasket design. Instead, the gasket relies on its groove-mounted configuration and conical rounded edge to provide sealing against the seat, eliminating the issue of lip bending and debris accumulation while maintaining effective sealing.
Solution Approach 2:
Rather than adding a lip that extends outward to seal, the invention inverts the approach by having the gasket seal against the seat with its conical rounded edge while mounted in a groove. The sealing surface faces the correct direction to prevent debris accumulation and bending issues.
3Reliability
If the non-return valve seat is arranged at a greater circumference than the stopcock sealing seat, then the sealing area is increased, but the pressure acting area becomes too large, reducing the pressure difference needed to lift the valve and making it difficult to meet overpressure requirements
Solution Approach 1:
The gasket is designed with different local properties: a conical rounded edge for sealing against the non-return valve seat and an annular planar sealing surface for the stopcock function. This localized differentiation allows the valve to meet stringent sealing requirements while maintaining appropriate pressure differential characteristics through optimized sealing geometry.
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 ensures a secure and compact sealing mechanism that prevents backflow and meets stringent sealing requirements, reducing wear and maintaining effective sealing across both stopcock and non-return valve functions, even under increased pressure.
Implementation Method 1
a conical, rounded edge (15) for sealing against a conical seat (24) in the valve housing (4)
Implementation Method 2
the annular gasket 16 arranged on the non-return valve piston sometimes blows off because the water penetrates under the gasket and the accompanying water pressure prises the gasket out of its groove
Implementation Method 3
a helical spring 22 disposed between the piston 8 and the end plug 9
Data Source
Figure 1~5
AI summary
A combination valve (1) for a water heater or plumbing and heating installation for a dwelling, which combination valve (1) includes a valve housing (4), a stopcock (2) with a stopcock spindle (7), a non-return valve (3) with a non-return valve piston (8), an inlet (5) and an outlet (6), which stopcock spindle (7) and which non-return valve piston (8) are centrically arranged along a common longitudinal axis of the valve (1), wherein the non-return valve piston (8) with a gasket (16) attached thereto is spring-actuated (22) for sealing contact with a first seat (19) in the valve housing (4) and the stopcock spindle (7) is threadedly received through an opening in the valve housing (4) or a part (9) attached thereto for sealing contact between the gasket (16) attached to the non-return valve piston (8) and a second seat (24) in the valve housing (4), and which first and second seats (19, 24) define a passage to the inlet (5) of the valve (1), the non-return valve piston (8) being centrically and slidably along the longitudinal axis arranged to an end of the stopcock spindle (7) for sealing contact between the gasket (16) attached to the non-return valve piston (8) and the first seat (19) in a closed position of the non-return valve (3) and, in addition, for sealing contact between the gasket (16) attached to the non-return valve piston (8) and the second seat (24) in a closed position of the stopcock (2) in which the gasket (16) is more compressed against the seat (18) than in the closed position for only the non-return valve (3), the first seat (19) being arranged further from the non-return valve piston (8) along the longitudinal axis than the second seat (24) and the seat (19) being arranged radially within the seat (24) in relation to the centric longitudinal axis.