scholarly journals Enhanced application limits for crossed helical gearboxes using new geometries for smaller sliding paths or smaller contact pressures

2019 ◽  
Vol 287 ◽  
pp. 01010
Author(s):  
Christoph Boehme ◽  
Dietmar Vill ◽  
Peter Tenberge
Keyword(s):  
Calculation Method ◽  
Helix Angle ◽  
Helical Gear ◽  
Design Parameters ◽  
Helical Gears ◽  
Positive Effects ◽  
Tooth Stiffness ◽  
Lubrication Condition ◽  
Overlap Ratio ◽  
Helical Gear Pair

Crossed-axis helical gear units are used as actuators and auxiliary drives in large quantities in automotive applications such as window regulators, windscreen wipers and seat adjusters. Commonly gear geometry of crossed helical gears is described with one pitch point. This article deals with an extended calculation method for worm gear units. The extended calculation method increases the range of solutions available for helical gears. In general, for a valid crossed helical gear pair, the rolling cylinders do not have to touch each other. In mass production of many similar gears, individual gears can be reused because they can be paired with other centre distances and ratios. This also allows the use of spur gears in combination with a worm, making manufacturing easier and more efficient. By selecting design parameters, for example the axis crossing angle or the helix angle of a gear, positive effects can be achieved on the tooth contact pressure, the overlap ratio, the sliding paths, the lubrication condition, the tooth stiffness and, to a limited extent, on the efficiency of the gearing. It can be shown that for involute helical gears, in addition to the known insensitivity of the transmission behaviour to centre distance deviations, there is also insensitivity to deviations of the axis crossing angle. This means that installation tolerances for crossed helical gearboxes can be determined more cost-effectively.

scholarly journals Effect of Helix Angle on the Gear Design Parameters in Helical Gears

2019 ◽  
Vol 8 (10) ◽  
pp. 887-890
Keyword(s):  
Helix Angle ◽  
Contact Stresses ◽  
Design Parameters ◽  
Screw Compressor ◽  
Bending Stress ◽  
Contact Ratio ◽  
Helical Gears ◽  
Gear Design ◽  
Overlap Ratio ◽  
Lower Noise

Screw compressor demands quite operation. For getting lower noise it is important to have higher contact ratio. Contact ratio can be increased by increasing the Helix angle i .e. indirectly increasing overlap ratio. The paper represents the effect of change in design parameters with respect to helix angle with the keeping same module and same centre distance. Higher helix angle leads lower bending and contact stresses. The study was conducted for screw electrical compressor. Gear was design for fixed parameters except helix angle. Also the contact stresses are analyzed (FEA) on ANSYS. The result from the calculation and FEA are compared for contact stress as well as bending stress.

Gear transmission error outside the normal path of contact due to corner and top contact

1999 ◽  
Vol 213 (4) ◽  
pp. 389-400 ◽  
Author(s):  
R. G. Munro ◽  
L Morrish ◽  
D Palmer
Keyword(s):  
Dynamic Test ◽  
Theoretical Models ◽  
Transmission Error ◽  
Helical Gear ◽  
Gear Transmission ◽  
The Novel ◽  
Transmission Systems ◽  
Helical Gears ◽  
Tooth Stiffness ◽  
Top Contact

This paper is devoted to a phenomenon known as corner contact, or contact outside the normal path of contact, which can occur in spur and helical gear transmission systems under certain conditions. In this case, a change in position of the driven gear with respect to its theoretical position takes place, thus inducing a transmission error referred to here as the transmission error outside the normal path of contact (TEo.p.c). The paper deals with spur gears only, but the results are directly applicable to helical gears. It systematizes previous knowledge on this subject, suggests some further developments of the theory and introduces the novel phenomenon of top contact. The theoretical results are compared with experimental measurements using a single flank tester and a back-to-back dynamic test rig for spur and helical gears, and they are in good agreement. Convenient approximate equations for calculation of TEo.p.c suggested here are important for analysis of experimental data collected in the form of Harris maps. This will make possible the calculation of tooth stiffness values needed for use in theoretical models for spur and helical gear transmission systems.

Calculation of Meshing Efficiency of Helical Gear Based on Double Integral Method

2016 ◽  
Vol 693 ◽  
pp. 458-462
Author(s):  
D.G. Chang ◽  
F. Shu ◽  
X.B. Chen ◽  
Y.J. Zou
Keyword(s):  
Experimental Data ◽  
Coordinate System ◽  
Theoretical Basis ◽  
Integral Method ◽  
Helical Gear ◽  
Design Parameters ◽  
Double Integral ◽  
Rectangular Coordinate System ◽  
Helical Gears ◽  
Theoretical Results

The meshing efficiency of helical gear transmission is calculated by using the method of double integral. The external involute helical gear meshing is taken and the model of helical gears is simplified by the idea of differential. The instantaneous efficiency equation of a meshing point is derived, and further more the rectangular coordinate system of meshing zone of helical gears is established. The average meshing efficiency of helical gears is achieved by using double integral method. Then, the influence of design parameters is studied and the efficiency formula is verified by comparing the theoretical results with relevant experimental data, which can provide a theoretical basis for decide the design parameters.

A Helical Gear Pair Pocketing Power Loss Model

2013 ◽  
Author(s):  
David Talbot ◽  
Ahmet Kahraman ◽  
Satya Seetharaman
Keyword(s):  
Fluid Dynamics ◽  
Power Loss ◽  
Control Volume ◽  
Fluid Pressure ◽  
Helix Angle ◽  
Helical Gear ◽  
Gear Pair ◽  
Dynamics Model ◽  
Gear Mesh ◽  
Helical Gear Pair

A new fluid dynamics model is proposed to predict the power losses due to pocketing of air, oil, or an air-oil mixture in the helical gear meshes. The proposed computational procedure treats a helical gear pair as combination of a number of narrow face width spur gear segments staggered according to the helix angle and forms a discrete, fluid dynamics model of the medium being pocketed in the gear mesh. Continuity and conservation of momentum equations are applied to each coupled control volume filled with a compressible fluid mixture to predict fluid pressure and velocity distributions from, which the instantaneous pocketing power loss is calculated. The proposed model is exercised in order to investigate fluid pressure and velocity distributions in time, as well as pocketing power loss as a function of speed, helix angle and oil-to-air ratio.

Pitting Load Capacity of Helical Gears

2007 ◽  
Author(s):  
Bernd-Robert Ho¨hn ◽  
Peter Oster ◽  
Gregor Steinberger
Keyword(s):  
Calculation Method ◽  
Load Distribution ◽  
Load Capacity ◽  
Test Results ◽  
Calculation Methods ◽  
Helical Gears ◽  
Capacity Calculation ◽  
Overlap Ratio ◽  
Tooth Flank

In experimental analyzes the pitting load capacity of case carburized spur and helical gears is determined in back-to-back test rigs. The research program with one type of spur and 8 types of helical gears includes tests for the determination of influences of varying load distribution, overlap ratio and transmission ratio. The test results are presented and evaluated on the basis of the pitting load capacity calculation methods of ISO 6336-2/DIN 3990, part 2. A new DIN/ISO compatible calculation method for pitting load capacity is presented. This new calculation method comprehends helical gears more adequate than ISO 6336-2 / DIN 3990, part 2 and has the possibility to consider tooth flank modifications. The new calculation method is applied on test results and gears of a calculation study. It shows better accordance with the experimental test results than the present ISO 6336-2 / DIN 3990, part 2.

Effects of Helix Angle on Root Stresses of Thin-Rimmed Helical Gears With Various Web Arrangements

2013 ◽  
Author(s):  
Kouitsu Miyachika ◽  
Daing Mohamad Nafiz Bin Daing Idris
Keyword(s):  
Strain Gauge ◽  
Helix Angle ◽  
Helical Gear ◽  
Stress Increment ◽  
Helical Gears ◽  
Web Structure ◽  
Single Tooth ◽  
Maximum Root ◽  
Root Stress ◽  
Increment Ratio

Root stresses of thin-rimmed helical gears with symmetric and asymmetric web arrangement of helix angle β0 = 10° and 20°, which were meshed with solid helical gear, were measured from the beginning of engagement to the end of the engagement by using the strain gauge method. The changes of root stresses from the beginning of engagement to the end of engagement were examined. The effects of helix angle, rim thickness, web thickness and web structure on the root stresses, the maximum root stress and the meshing position, where the maximum root stress (worst loading position) occurs, were clarified. Furthermore, the obtained results were compared with the results of the solid helical gear. On the basis of these results, the maximum root stress of thin-rimmed helical gears with helix angle β0 = 10° occurs at the outer point of single tooth contact, and at the position of a transverse base pitch distant from the tip toward the root along the line of action for β0 = 20°. For thin-rimmed helical gears with the same rim thickness, web thickness and web structure, maximum root stress increment ratio (maximum root stress of thin-rimmed helical gear divided by maximum root stress of solid helical gear) of thin-rimmed helical gears with helix angle β0 = 10° are larger compared to the case of β0 = 20°.

External High-Order Multistage Modified Elliptical Helical Gears and Design Procedure of Its Gear Pair

2014 ◽  
Author(s):  
Jiang Han ◽  
Youyu Liu ◽  
Dazhu Li ◽  
Lian Xia
Keyword(s):  
Design Procedure ◽  
Mathematical Expression ◽  
Gear Ratio ◽  
Helical Gear ◽  
High Order ◽  
Curvature Radius ◽  
Gear Pair ◽  
Contact Ratio ◽  
Helical Gears ◽  
Helical Gear Pair

In view of the limited number of the modified segments for high-order and two-stage modified elliptical helical gears, and poor adjustment capacity for gear ratio, the formation mechanism of a high-order multistage modified ellipse was studied, and a unified mathematical expression of the family of ellipses was obtained. Thus, a design procedure for the helical gear pair of the high-order multistage modified ellipse was suggested, and its transmission characteristics were discussed exhaustively. Moreover, some checking methods such as the curvature radius of the pitch curve, convexity, pressure angle, root cutting, and contact ratio were offered. Finally, two design cases, including two-order and three-stage modified elliptical helical gear pair and two-order and four-stage one, were implemented. The cases indicate that a high-order multistage modified elliptical helical gear can be utilized in practice.

Utilization of Tooth Contact Pattern in a Gear Meshing Model for Estimation of Sliding Loss in a Parallel-Axis Gear Pair

2014 ◽  
Vol 619 ◽  
pp. 68-72
Author(s):  
Jetsada Phraeknanthoe ◽  
Natcha Ponchai ◽  
Chanat Ratanasumawong
Keyword(s):  
Helix Angle ◽  
Helical Gear ◽  
Experimental Results ◽  
Gear Pair ◽  
Contact Pattern ◽  
Tooth Contact ◽  
Parallel Axis ◽  
Helical Gear Pair

The utilization of tooth contact pattern in a gear meshing model for estimation of sliding loss in a spur and helical gear pair is presented in this paper. The photo of tooth contact pattern taken after the gear operation is used as the database to generate the simplified tooth contact pattern. Then the simplified contact pattern is used along with the gear meshing model to estimate the sliding loss of a gear pair. Experiments are done to verify the results. The estimated results from the presented method agree well with the experimental results. The presented method is able to estimate the effect of the helix angle on the sliding loss correctly whereas the estimation without using the data of tooth contact pattern cannot.

Modal Analysis and Parameters Research of Internal Helical Gears Based on AWE

2011 ◽  
Vol 86 ◽  
pp. 904-907 ◽  
Author(s):  
Yan Jun Gong ◽  
Xue Yao Wang ◽  
Han Zhao ◽  
Kang Huang
Keyword(s):  
Modal Analysis ◽  
Natural Frequency ◽  
Helix Angle ◽  
Helical Gear ◽  
Vibration Characteristics ◽  
Helical Gears ◽  
Pressure Angle ◽  
Number Of Teeth ◽  
Gear Change

The paper conducted a modal analysis of an internal helical gear based on AWE, and obtained its first 6 order natural frequency. Then the paper analyzed the influence of its parameters on the vibration characteristics of the internal helical gear, found that if the helix angle, the normal module, the number of teeth of the internal helical gear change, its vibration characteristics will change, but the change of the pressure angle doesn’t influence its vibration characteristics.

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