Research On The Key Technologies Of High Performance Circular Arc Gear Pump

The gear pump is one of the most commonly used hydraulic transmission system elements,and is used in the aviation,aerospace,aircraft,marine,and automobile industries,among others.It is widely used because of its simple construction,small volume,and low oil pollution.Due to rapid developments in technology,the requirements for high performance are increasing.The main purpose of the gear pump is to realize high speed,high pressure,and miniaturization.In order to obtain a high performance gear pump,it is necessary to study and analyze the gear pump under conditions of high pressure and miniaturization.Improvements in the design to overcome existing problems were researched,and a basic model and method were provided for future research.The rotor is one of the key components of the gear pump,and is the foundation and key point of gear pump research.In order to solve the problems of increase in trap oil and flow rate fluctuations with high speeds,high pressures,and miniaturization,a mathematical analysis of the rotor was conducted in this study.The circular-arc tooth profile was used,which was generated by means of an involute tooth profile.In addition,the tooth profile and performance parameters were analyzed.The flow rate fluctuations caused by trap oil were eliminated,and,in theory,the phenomenon of no trap oil was achieved in theory to by set the relationship between modulus,face width,and spiral angle.A basic model for subsequent research was provided.The fluid flow states of the gear pump were altered for high speeds,high pressures,and miniaturization.In order to examine the flow-field of a circular-arc gear pump,a computational model was established and a numerical simulation was conducted using ANSYS Fluent software.The key factors that affect the overall performance,such as the location at which the maximum pressure and cavitation occur as well as fluctuations in the inlet and outlet flow rate were obtained by setting different work conditions.This also provided a reference for subsquent design of important parts of the gear pump.An increase in inner leakage and wear of parts,and a reduction in volume were accompanied by an increase in pressure and rotational speed.The inner leakage is an important index for evaluating the overall performance of the gear pump,and it affects the volumetric efficiency.In order to solve the intensified leakage problems,a radial leakage and an end face leakage model were established in this paper.The designs of parts of the gear pump were based on the study and analysis of radial and end face leakages.The minimum energy losses were also obtained by optimizing the radial and end clearances.To reduce the wear and damage of journal bearings under high speed and high pressure,hydrostatic journal bearings were designed.The lubrication of the hydrostatic journal bearings was achieved and a part of the radial forces was offset by introducing high-pressure oil into the hydrostatic journal bearings.This generated a supporting force width that was opposite to the direction of the radial force.Due to the special tooth profile,tools for gear machining were designed.In order to obtain the tooth profile,methods of using a disc milling cutter,gear hob,and ball end milling cutter to process the tooth profiles are presented in this paper.The axial cross section of the disc milling cutter,hob rake face,and basic worm were obtained by the principles of gearing mesh.In addition,an NC machine with ball end mill was used in this paper.The proper radius of the ball end mill was obtained by judgment of interference and simulation of the machining trajectory.In order to improve the machining efficiency and reduce cost,the involutes were substituted with two circular arcs.In order to improve the computational efficiency of the gear pump with different dimensions,the design systems,including tooth profile design,analysis of performance,examination of tooth profile,and tool design were developed.Based on the circular-arc gear pump designed in this paper,performance test systems andplatforms were developed.The acquisition and processing of pressure,flow rate,and rotational speed signals were completed using the Lab VIEW software.In order to obtain the desired volumetric efficiency under different conditions,experiments under loaded and unloaded conditions were conducted.Comparison experiments were conducted to verify the effectiveness of the hydrostatic journal bearings that include the radial force offset.