Hydrostatic Radial Piston Machine Magnetic Piston Retraction
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Solution Overview
Problem
Current hydrostatic radial piston machines face inefficiencies in reduced displacement modes due to pistons performing braking and wear-inducing idle strokes, particularly when operating in switchable groups with interrupted pressure.
Innovation Solution
The machine is designed with a group of always-active lobes and a switchable group, where pistons are individually retracted into the cylinder block using magnetic force when passing over deactivated lobes, minimizing contact and optimizing efficiency by maintaining a radial gap, and utilizing a 5/2-way valve for smooth mode transitions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If pressure is interrupted to pistons in switchable group for reduced displacement mode, then displacement mode is reduced, but pistons perform braking and wear-inducing idle strokes
Solution Approach 1:
The patent replaces the mechanical pressure interruption system with a magnetic field-based piston retraction system. Magnets mounted on the cam body attract and hold pistons in retracted positions when lobes are deactivated, eliminating the need for pressure control mechanisms and preventing idle strokes that cause energy loss and wear.
Solution Approach 2:
The patent extracts the harmful idle stroke action by physically removing pistons from contact with deactivated lobes through magnetic retraction. This separates the useful function (active lobes driving pistons) from the harmful function (deactivated lobes causing braking and wear), allowing independent control of each lobe group.
2Loss of energy
If pistons are retracted using magnetic force, then efficiency is improved by preventing idle strokes, but device complexity increases
Solution Approach 1:
The cam body serves multiple functions: it generates the cam profile for active lobes, provides magnetic attraction for piston retraction, and acts as the structural support for the entire mechanism. This multi-functionality reduces the need for separate components and simplifies the overall device structure despite adding magnetic control capability.
Solution Approach 2:
The patent combines the magnetic retraction system with the existing cam body structure, integrating magnets directly into the cam body rather than adding separate retraction mechanisms. This merging approach increases functionality while minimizing additional structural complexity.
3Reliability
If all lobes are always active, then continuous power transmission is maintained, but energy consumption increases in reduced displacement modes
Solution Approach 1:
The patent implements dynamic control of lobe activation, allowing the system to switch between full displacement mode (all lobes active) and reduced displacement mode (selective lobe deactivation). The magnetic retraction system enables pistons to dynamically respond to lobe activation states, maintaining reliability when needed while reducing energy consumption during reduced displacement operation.
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 efficiency in reduced displacement modes by preventing idle strokes and wear, while maintaining operational reliability and noise reduction, and allows for seamless transitions between full and reduced displacement modes.
Implementation Method 1
each piston is individually pullable into the cylinder block by magnetic force and can be kept there in a retained position when the assigned cylinder hole is in operative connection with a lobe of the switchable group
Data Source
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AI summary
Disclosed is a hydrostatic radial piston machine which may be a motor and/or a pump. The machine is configured to operate in the full displacement mode and additionally in one or more reduced-displacement modes. To optimize the efficiency of the machine in the reduced-displacement modes the pistons can be retained in their cylinder holes when they pass one of the deactivated lobes.