Two-part piston rod for brake pump pressure dynamics
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Solution Overview
Problem
Existing piston pumps for vehicle brake systems suffer from slow pressure build-up dynamics due to high flow resistance in long suction lines and are costly to manufacture.
Innovation Solution
A two-part piston rod design with a fluid inlet opening that minimizes flow resistance, combined with a one-piece sealing element and receiving means, and a snap connection for easy assembly and reduced component count, allowing for quick filling and cost-effective production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a long suction line is used in the piston rod, then the structural integrity is maintained, but the flow resistance increases and pressure build-up dynamics deteriorate
Solution Approach 1:
The piston rod is divided into two separate elements: a first piston rod element containing the fluid inlet opening and a second piston rod element that partially covers it. This segmentation allows the suction line to be shortened significantly while maintaining the structural function of the piston rod, thereby reducing flow resistance and improving pressure build-up dynamics
2Productivity
If a one-piece piston rod is used, then the manufacturing process is simplified, but the flow resistance increases due to the long suction line
Solution Approach 1:
The piston rod is segmented into two elements where the first element has the fluid inlet opening and the second element covers it partially. This allows optimization of the fluid flow path independent of the structural requirements, enabling faster pressure build-up without excessive structural complexity
Solution Approach 2:
The fluid inlet opening is positioned in the first piston rod element while being partially covered by the second element in the axial direction. This spatial arrangement in multiple dimensions allows the suction line to be shortened without compromising the structural integrity or assembly simplicity of the piston rod
3Ease of manufacture
If the sealing element and receiving means are separate components, then the assembly flexibility is maintained, but the manufacturing cost and assembly complexity increase
Solution Approach 1:
The sealing element and the receiving means for the inlet valve are merged into a single integrated component. This reduces the total number of parts, simplifies assembly procedures, and lowers manufacturing costs while maintaining the functional requirements of both sealing and valve reception
4Ease of operation
If the piston rod elements are connected with a press fit, then the assembly is simplified, but the connection strength may be insufficient
Solution Approach 1:
The piston rod is segmented into two elements connected by a press fit, allowing simplified assembly compared to more robust connection methods. The press fit provides sufficient connection strength for the application while maintaining ease of assembly and disassembly
Data Source
AI summary
The invention relates to a piston pump (10) for a motor vehicle braking system, comprising a housing section (12) and a piston (26) that is displacably guided into the housing section (12), and receiving means (20) for receiving an inlet valve (22), a sealing element (18) that is connected to the receiving means (20) for sealing the piston (26) counter to the housing section (12) and a piston rod (62) that is joined to the sealing element (18). Said piston rod (62) has two parts having a first (28) and a second piston rod element (30). In the first piston rod element (28), a fluid inlet (64) for introducing the fluid into the inside of the piston (26) is provided, and the second piston rod element (30) partially covers the fluid inlet (64) in the axial direction of the piston (26).