Piston Pump Seal Member Stroke Length Design
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Solution Overview
Problem
Existing piston pumps in hydraulic control apparatuses for vehicles face issues where brake fluid can invade the cam chamber due to scratches or dents on the cylinder or piston, compromising the seal between the pump and cam chambers.
Innovation Solution
The piston pump incorporates a seal member with two sliding contact surfaces, where the seal section length is greater than the piston's stroke length, ensuring that any scratches or dents allow fluid invasion only beyond one contact surface, and the seal member's thickness is minimized to reduce the pump's size, using an oval-shaped section or X-shaped seal member with surface-pressure-peak portions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the seal member has a standard thickness, then the pump size is reduced, but the seal section length becomes insufficient to prevent fluid invasion through scratches or dents
Solution Approach 1:
The seal member is designed with an extended seal section that protrudes into the pump chamber, adding a dimensional element beyond the standard thickness. This extension creates a longer seal path (L1) that prevents fluid invasion through scratches or dents while maintaining compact overall pump dimensions.
Solution Approach 2:
The seal section is positioned and extended in advance to cover the entire piston stroke range. By pre-positioning the seal section to extend beyond the maximum stroke endpoints, the design ensures that any scratches or dents on the piston surface cannot breach the seal, as the seal section already covers the full range of motion.
2Reliability
If the seal section length is increased to prevent fluid invasion, then the reliability improves, but the pump size increases
Solution Approach 1:
The seal member features localized quality variation with a seal section that has different dimensional characteristics than the rest of the member. The seal section is extended in the axial direction to provide enhanced sealing length precisely where needed, while other portions of the seal member maintain standard dimensions to minimize overall size.
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 design effectively prevents brake fluid from entering the cam chamber, even with scratches or dents, while reducing the pump's size by ensuring the seal section is longer than the piston's stroke length, thereby maintaining fluid separation and minimizing fluid leakage.
Implementation Method 1
the two sliding contact surfaces (53) respectively include a surface-pressure-peak portion (52) having the highest surface pressure
Data Source
Figure 1
Figure 2A~2B
Figure 3A~3B
AI summary
According to an aspect of the present invention, there is provided a piston pump (1), comprising: a cylinder (10) formed in a pump body (100); a piston (40) reciprocatable within the cylinder (10); and a seal member (50, 50A) interposed between the cylinder (10) and the piston (40) for sealing fluid tight between a pump chamber (30) and a cam chamber (130), the pump chamber (30) being formed on one end (40a) side of the piston (40) in a sliding direction thereof, the cam chamber (130) being formed on the other end (40b) side of the piston (40) in the sliding direction, wherein the seal member (50, 50A) includes a sliding contact surface (53) closely contactable with the cylinder (10) or the piston (40) and a seal section (L1, L3) to be sealed by the sliding contact surface (53) in the sliding direction of the piston (40), and wherein a length of the seal section (L1, L3) is larger than a stroke length (S1) of the piston (40).