Piston Pump Seal Structure for High Pressure Stability
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Solution Overview
Problem
The existing sealing structures for pistons in cylinder systems, particularly in piston pumps and brake hydraulic pressure control devices, face issues with insufficient sealing performance due to changes in the posture of the seal member during axial reciprocation, leading to fluid leakage and wear of the rubber parts, especially under high hydraulic pressure conditions.
Innovation Solution
An improved sealing structure featuring a synthetic resin seal member with an annular groove and a pressing member that urges the center portion of the seal member towards the cylinder or piston, maintaining higher surface pressure at the axial center portion to prevent fluid leakage and reduce wear, while the engaging portions prevent separation and minimize load on the seal member.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a seal member pressed by an O-ring is provided in an annular groove with flanges for preventing O-ring coming-off, then the seal member can be retained in position, but the O-ring presses the flanges during axial reciprocation which makes the posture of the seal member unstable and causes pumping phenomenon
Solution Approach 1:
The invention removes the flanges from the seal member structure. Instead of having flanges that protrude and get pressed by the O-ring, the seal member has a smooth outer circumferential surface that fits into the annular groove without protruding elements. This eliminates the source of instability while maintaining retention through the groove geometry itself.
Solution Approach 2:
Instead of using flanges to prevent O-ring coming-off (active retention), the invention uses the annular groove geometry to passively retain the seal member. The O-ring is contained within the groove structure rather than being prevented from escaping by protruding flanges. This inversion of the retention mechanism eliminates the pressing action on flanges during reciprocation.
2Stability of the object's composition
If peak regions of sealing surface pressure are formed at plural places spaced axially on the sliding surface, then the seal member posture can be stabled, but the surface pressures at respective seal portions change alternately causing fluid leakage through pumping phenomenon
Solution Approach 1:
The invention creates a localized high-pressure sealing region at the axial center portion of the seal member rather than distributing peak pressure regions at multiple axial locations. The O-ring is positioned to press the axial center portion, creating a concentrated sealing zone where the seal member contacts the cylinder, ensuring consistent sealing pressure without the alternating pressure changes that cause pumping.
Solution Approach 2:
The sealing function is segmented into a primary sealing region at the axial center and separate retention functions. The flanges are removed entirely, and the annular groove provides both the sealing surface and the retention structure, separating the sealing function from the retention function that were previously combined in the flanged design.
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 enhances sealing performance by maintaining consistent surface pressure, reducing fluid leakage, and extending the service life of the sealing structure by minimizing wear and the 'pumping phenomenon', even under high hydraulic pressure conditions.
Implementation Method 1
a pressing member arranged on an outer or inner circumferential side of the seal member in the annular groove for urging an axial center portion of the seal member toward the cylinder or the outer circumferential surface of the piston
Implementation Method 2
a seal member made of a synthetic resin material to an annular shape and fitted in the annular groove so that a seal surface formed on an inner or outer circumferential surface thereof contacts the other of the cylinder and the outer circumferential surface of the piston for fluid-tightly sealing
Data Source
AI summary
A sealing structure is provided wherein an annular groove formed in a pump cylinder of a piston pump receives therein a seal ring made of a synthetic resin material and having an inner circumferential surface fluid-tightly contacting an outer circumferential surface of the pump piston and an O-ring arranged on the outer circumferential side of the seal ring and urging the seal ring radially inward. The seal ring is formed at its axial end portions with flange portions for preventing the O-ring from coming off. In the state that the seal ring and the O-ring are fitted in the annular groove, the flange portions do not receive a load from the O-ring, and a surface pressure which the seal ring applies to the outer circumferential surface of the piston at an axial center portion thereof is set to be higher than surface pressures which it applies to the outer circumferential surface of the piston at axial end portions thereof.