Ceramic Piston Assembly for Thermal Stress and Leak Resistance
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Solution Overview
Problem
Pistons in volumetric pumps, especially those made of metal, face significant mechanical stress and thermal expansion issues due to operating temperature and pressure variations, leading to performance reduction and wear, and are prone to leaks and damage from corrosive fluids, with existing ceramic solutions vulnerable to compression and material degradation.
Innovation Solution
A piston design comprising a metal first portion and a ceramic second portion, where the ceramic portion has a closed free base and a cavity for the metal stem, eliminating the need for compressive fastening elements and allowing for secure, stress-free assembly, with a pin and through holes for firm coupling and easy disassembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a metal piston is used, then the piston can be easily manufactured and assembled, but it suffers from thermal expansion, mechanical stress, and wear under high temperature and pressure
Solution Approach 1:
The piston is constructed as a composite structure with a metal body providing mechanical strength and ease of manufacturing, while a ceramic sleeve provides thermal resistance and wear protection. This composite approach allows the piston to withstand high temperature and pressure environments reliably while maintaining manufacturability through conventional metalworking techniques for the body and ceramic coating or inlay processes.
2Reliability
If a ceramic sleeve is used in the piston, then thermal and pressure resistance is improved, but the piston becomes vulnerable to compression damage from excessive fastening
Solution Approach 1:
The piston is divided into distinct segments: a metal body, a ceramic sleeve, and a separate retaining ring. The retaining ring provides the necessary compression and retention of the ceramic sleeve without requiring direct fastening of the ceramic material itself. This segmentation allows the ceramic to maintain its integrity while still being securely held in place, preventing both compression damage and operational displacement.
3Ease of operation
If fastening elements are used to secure the ceramic sleeve, then the sleeve is retained in position, but leaks can occur through clearance between stem and sleeve as components deteriorate
Solution Approach 1:
A retaining ring serves as an intermediary component between the metal body and the ceramic sleeve. This retaining ring maintains the proper positioning and clearance of the ceramic sleeve throughout operation, compensating for wear and thermal expansion. The intermediary element ensures that the ceramic sleeve remains securely retained without direct fastening, preventing leaks while allowing for normal operational movement and thermal cycles.
4Reliability
If the ceramic sleeve is tightly fastened, then it is securely retained, but excessive tightening can cause cracks, tears or breaks in the sleeve
Solution Approach 1:
The fastening function is separated from the ceramic sleeve by introducing a retaining ring as a distinct component. The retaining ring applies the necessary retention force while distributing it evenly, preventing localized excessive tightening that would cause ceramic damage. The ceramic sleeve itself is not directly fastened but rather retained by the intermediary ring, which can be adjusted and replaced without damaging the ceramic.
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 design enables reliable, long-lasting operation under high temperatures and pressures, prevents fluid leaks, and withstands corrosive fluids, ensuring consistent performance and reduced risk of damage from thermal stress and chemical attack.
Implementation Method 1
the operating temperature and pressure of the pump, the temperature of the pumped fluid and/or the variations thereof may subject a piston - especially if it is made of metal material - to a significant mechanical stress and to thermal expansion and contraction cycles
Implementation Method 2
ceramic materials (such as for example, alumina) are thermally refractory materials that are resistant to increased pressures
Implementation Method 3
which may also be processed on surfaces provided with a highly contained friction coefficient
Data Source
Figure 1~2
Figure 3A~4B
Figure 5A~6B
AI summary
A piston (1) comprising a first portion (10) suitable for coupling with an actuator member (53) and a second portion (20) made of ceramic material suitable for sliding in a cylinder (51). The first portion (10) and the second portion (20) are axially connected along a longitudinal axis (L) of the piston (1). The second portion (20) has an elongated shape along the longitudinal axis (L) of the piston (1), with an interface base (21) proximal to the first portion (10) and a free base (23) distal from the first portion (10). Moreover, the free base (23) is closed and entirely defines a piston crown.