Curvilinear circular-arc tooth gears for use in external gear pumps
a gear tooth and circular arc technology, applied in the field of gear teeth, can solve the problems of pocket pressure rising, tooth not fully filled, pocket of fluid being trapped between the teeth, etc., and achieve the effect of reducing the shock stress on the gear teeth and noise during meshing, and reducing the net axial load
Inactive Publication Date: 2020-04-23
THE UNITED STATES OF AMERICA AS REPRESENTED BY THE SECRETARY OF THE NAVY
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Benefits of technology
The invention is a curvilinear circular-arc-toothed (CCAT) gear that improves gear performance and reduces noise while avoiding axial loads common to helical gears. The gear tooth has a cross-sectional profile formed from a hybridization of two or more curves, the axial tooth profile being symmetric across the midplane of the gear to reduce axial loading on gears induced by gear meshing. The gear tooth has a hybrid gear tooth profile with a tip that conforms to the tooth root of the mating gear to allow fully swepping out the volume between gear teeth to improve efficiency and reduce noise. The axial profile is configured to cause gradual contact between teeth to reduce shock stress on the gear teeth and noise during meshing. The technical effects of the invention include improved gear performance, reduced noise, and reduced axial loads on the gear.
Problems solved by technology
The key disadvantage of an involute profile is that during the meshing action, the addendum of one tooth does not fully sweep the dedendum of the corresponding tooth of the mating gear.
This results in a pocket of fluid being trapped between the teeth during meshing.
Method used
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[0038]The primary drawback to involute tooth profiles in gear pumps is that the tooth of one gear does not fully sweep the tooth space of the mating gear. As the teeth progressively merge, a pocket of fluid is trapped and increasingly compressed by the continuing meshing action. The pressure of this fluid pocket is continually increased to a level sufficient to force a fluid flow rate between the gear teeth equal to the volume loss rate of the pocket (minus the effect of fluid compressibility). For gears with minimal backlash (and thus a tight mesh), as desired in gear pumps, this can result in very high pressures within the fluid pocket that can damage the tips of the gear teeth. The rapid pressurization of the fluid also contributes to the noise level of the pump. Various efforts have been done over time to model the meshing dynamics of involute spur gears in this regard.
[0039]While there are multiple avenues to mitigate the pressure oscillations, the most common is the relief gro...
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A curvilinear circular-arc-toothed (CCAT) gear for improving gear performance and reducing noise while avoiding axial loads common to helical gears includes an annular gear body; and a gear tooth having a hybrid gear tooth profile comprising one or more curves configured to provide a sweep of the gear tooth space by a mating gear tooth while maintaining smooth contact during gear mesh, and wherein the gear tooth extends along an axial length of the gear body along an axial profile.
Description
RELATED APPLICATIONS[0001]This application claims the benefit of U.S. Provisional Application No. 62 / 749,498 filed Oct. 23, 2018, which is hereby incorporated herein by reference.FEDERALLY-SPONSORED RESEARCH AND DEVELOPMENT[0002]The United States Government has ownership rights in this invention. Licensing inquiries may be directed to Office of Technology Transfer, US Naval Research Laboratory, Code 1004, Washington, D.C. 20375, USA; +1.202.767.7230; techtran@nrl.navy.mil, referencing NC 107458.FIELD OF INVENTION[0003]The present invention relates generally to gears, and more particularly to gears used in gear pumps.BACKGROUND[0004]The basic function of an external gear pump as shown in FIG. 1, is to drive the flow of a fluid through the rotary action of two meshed gears. At one side of the meshing zone (termed the suction side), the gear teeth unmesh, creating a void that draws fluid into the tooth spaces of the gears. These fluid packets are then rotated around the gear into the d...
Claims
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IPC IPC(8): F04C15/00F04C2/08
CPCF04C15/0042F04C2/084F04C2/18F04C2230/10
Inventor WILLIAMS, LOGAN
Owner THE UNITED STATES OF AMERICA AS REPRESENTED BY THE SECRETARY OF THE NAVY