Stepped Piston Pump for Hydraulic Braking Flow Stability
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Solution Overview
Problem
Conventional piston pumps in hydraulic vehicle braking systems experience uneven fluid flow and pressure pulsations due to the lack of a mechanism to manage fluid displacement on both forward and return strokes effectively.
Innovation Solution
A piston pump design featuring a stepped piston with a displacement chamber and a step chamber, where the stepped piston is driven in a reciprocating motion within a stepped pump bore, allowing for fluid displacement into the pump outlet on both strokes, and incorporating a pressure-controlled or differential pressure valve to separate the step chamber from the pump outlet during high back-pressure, ensuring consistent fluid flow and reduced pressure pulsations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a conventional piston pump design is used without a step chamber, then the structure is simpler, but the fluid flow becomes uneven and pressure pulsations increase
Solution Approach 1:
The piston is segmented into different diameter sections (first piston section with larger diameter, second piston section with smaller diameter), creating distinct displacement and step chambers. This segmentation allows the pump to discharge fluid through different pathways during forward and return strokes, stabilizing the overall fluid flow and reducing pressure pulsations despite the added structural complexity.
2Volume of stationary object
If the step chamber cross-section is made larger to match the displacement chamber, then the volume change balance improves, but the pump outlet flow uniformity deteriorates
Solution Approach 1:
The step chamber is designed with a specifically controlled smaller cross-section compared to the displacement chamber. This local differentiation in chamber dimensions creates an asymmetric volume change relationship where the step chamber volume change is intentionally kept smaller, allowing the pump to maintain balanced discharge across both strokes while preserving flow uniformity at the outlet.
3Device complexity
If the pump operates without a pressure-controlled valve, then the device is simpler, but the fluid displacement consistency during high back-pressure deteriorates
Solution Approach 1:
A pressure-controlled valve is introduced that dynamically responds to back-pressure conditions. When back-pressure exceeds a predetermined threshold, the valve automatically closes to isolate the step chamber from the pump outlet, preventing reverse flow and maintaining consistent fluid displacement. This dynamic control mechanism ensures reliable operation under varying pressure conditions despite adding valving complexity to the system.
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 achieves a more even fluid flow and reduced pressure pulsations on both the suction and pressure sides of the piston pump, maintaining consistent fluid displacement on both forward and return strokes, thereby enhancing the performance of hydraulic vehicle braking systems.
Implementation Method 1
the stepped piston of the known piston pump displaces fluid from the displacement chamber into the pump outlet
Implementation Method 2
the known piston pump sucks in fluid from a pump inlet through an inlet valve into the displacement chamber
Implementation Method 3
a valve system that separates the step chamber from the pump outlet during high back-pressure
Data Source
AI summary
A reciprocating pump, in particular a hydraulic pump of a slip-controlled vehicle braking system, includes a step piston, a differential pressure valve, and a pump outlet. The step piston includes a piston step that delimits a stepped space which is in communication with the pump outlet via the differential pressure valve. The piston step is configured such that the step space undergoes suction and displacement in a direction opposite to a displacement space, and in smaller quantities than suction and displacement in the displacement space, such that brake fluid volume flow in the pump outlet is evened out, and such that pressure pulsations are inhibited.