Geroller Hydraulic Motor Anti-Cogging Passages
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Solution Overview
Problem
Geroller hydraulic motors exhibit cogging at low speeds, which is objectionable in certain applications such as lawn equipment, leading to jerking or detenting in rotational output, especially at high fluid pressures and low rotational speeds.
Innovation Solution
Incorporation of anti-cogging passages in the geroller hydraulic motor, specifically shallow and narrow grooves in the manifold and wear plate, to communicate fluid pressure to the rollers, reducing cogging by ensuring consistent pressure distribution and minimizing leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If geroller hydraulic motors operate at high fluid pressures and low rotational speeds, then torque output is improved, but cogging occurs causing jerking or detenting in rotational output
Solution Approach 1:
The patent introduces anti-cogging passages as intermediary fluid channels that mediate between the main fluid supply and the rollers. These passages ensure continuous fluid supply to the rollers during rotation, preventing pressure fluctuations that cause cogging. The passages act as a buffer that smooths out the intermittent fluid delivery that would otherwise occur as gears mesh and unmesh.
Solution Approach 2:
The anti-cogging passages are designed to supply fluid pressure to the rollers in advance of their engagement with the gear teeth. This preliminary fluid pressure ensures that rollers are already pressurized and ready to engage smoothly, preventing the jerking motion that occurs when rollers suddenly engage without adequate pressure.
2Manufacturing precision
If dimensional tolerances in the hydraulic motor are tight, then manufacturing precision is improved, but cogging is reduced only marginally at low speeds
Solution Approach 1:
The patent applies hydraulic principles by introducing dedicated fluid passages that use fluid pressure to counteract the mechanical imperfections caused by dimensional tolerances. The anti-cogging passages use fluid pressure distribution to ensure smooth roller engagement, compensating for variations in gear tooth dimensions and roller fit tolerances that would otherwise cause cogging at low speeds.
3Ease of operation
If anti-cogging passages are added to the hydraulic motor, then rotational smoothness is improved, but device complexity increases
Solution Approach 1:
The anti-cogging passages are merged with the existing manifold and wear plate structures. Rather than adding separate components, the passages are integrated into the existing housing and gear assembly, using the same manufacturing processes and materials. This combining approach reduces the overall device complexity while still achieving the anti-cogging function.
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 anti-cogging passages effectively reduce cogging in at least one rotational direction, improving the motor's performance and operator experience by smoothing the rotational output, particularly at low speeds and high pressures.
Implementation Method 1
anti-cogging passages in the geroller hydraulic motor, specifically shallow and narrow grooves in the manifold and wear plate, to communicate fluid pressure to the rollers
Data Source
AI summary
A hydraulic motor receives pressurized fluid from a source controlled by a human operator to convert the energy in the hydraulic fluid to a rotational output to propel a drive wheel of a machine. The hydraulic motor includes an end cover, a manifold, a drive assembly, a wear plate, a housing, and an output assembly. The drive assembly includes a rotor with external teeth and a stator with internal teeth formed by rollers having end faces. The pressurized fluid from the source flows through the manifold to the drive assembly and causes rotational and orbital movement of the rotor relative to the stator. The rotational movement of the rotor is transmitted to the drive wheel by the output assembly. A first set of anti-cogging passages and a second set of anti-cogging passages communicate fluid pressure to the end faces in timed relationship to reduce cogging or detenting of the rotational output of the motor.