Effect of Coupling between Tooth Side Clearance and Lubricant Viscosity of Spur Gear

The figure shows the distribution cloud of the tooth surface contact temperature on the lubricant viscosity and the tooth side clearance plane at rotational speed n=1 800 r/min and torque T=10 N_m in the state of elastohydrodynamic lubrication and mixed lubrication.

It can be seen from the diagram that the contact temperature of tooth surface under EHL during gear meshing is positively correlated with the viscosity of lubricating oil. It is also found that the contact temperature of tooth surface increases slightly with the increase of tooth side clearance.The tooth contact temperature under mixed lubrication also increases with the increase of the tooth side clearance; however, the tooth contact temperature under mixed lubrication is negatively correlated with the lubricant viscosity.The contact temperature of tooth surface under both lubrication conditions increases with the increase of tooth side clearance, which is due to the increase of energy loss, friction heat generation and tooth side contact temperature as the tooth side clearance increases.At the same time, it will cause impact on the tooth surface of the gear, aggravate the vibration of the gear box, increase the noise and even produce rodenting phenomenon.It can be seen from the diagram that the backlash on the tooth side increases from 0 to0.25Mm, the contact temperature of tooth surface rises by about 2-3 degrees Celsius.Under different lubrication conditions with the same tooth side clearance, the influence of lubricant viscosity on the contact temperature of tooth surface is different and to varying degrees.Under the condition of Elastohydrodynamic lubrication, the temperature increases significantly with the increase of lubricant viscosity; under the condition of mixed lubrication, the temperature of tooth contact decreases slightly with the increase of lubricant viscosity.Therefore, it can be seen that although the influence of the tooth side clearance on the contact temperature of the tooth surface is not very great, the increase of the tooth side clearance will cause tooth surface impact and generate huge noise pollution, and at the same time increase the gear loss.Therefore, reasonable range of tooth side clearance should be selected in practical engineering.

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