scholarly journals Friction and wear analysis of the external return spherical bearing pair of axial piston pump/motor

2020 ◽  
Vol 21 (1) ◽  
pp. 104 ◽  
Author(s):  
Haishun Deng ◽  
Cong Hu ◽  
Qingchun Wang ◽  
Lei Wang ◽  
Chuanli Wang
Keyword(s):  
Contact Point ◽  
Power Fluctuation ◽  
Rotating Speed ◽  
Friction Power ◽  
Swash Plate ◽  
Discrete Contact ◽  
Spring Force ◽  
Spherical Bearing ◽  
Pump Shaft ◽  
Fluctuation Amplitude

By discretizing the contact area between the external retainer plate and the external spherical hinge, a mathematical model for the force relation of an arbitrary contact point in the external return spherical bearing pair was established and a mathematical expression for the friction power of the external return spherical bearing pair was deduced. The influences of the slant inclination of the external swash plate, pump shaft rotating speed, eccentricity, spring force and number of discrete contact points on the friction power were also analysed. The results show that the power fluctuation amplitude of the discrete contact point in the external return spherical bearing pair increases with increasing slant inclination of the external swash plate, pump shaft rotating speed and spring force; the total friction power was found to increase linearly. However, the power fluctuation amplitude of the discrete contact point in the external return spherical bearing pair was found to decrease with increasing eccentricity, with the total friction power decreasing nonlinearly until reaching a certain value. The distribution shape of the friction power of the discrete contact point is only affected by eccentricity. If the eccentricity is large, the friction power of the discrete point presents a double-peak distribution, whereas if it is small, a multiple-peak distribution is observed.

Relative motion relation in the external return spherical bearing pair of a balanced double-row axial piston pump

2018 ◽  
Vol 233 (11) ◽  
pp. 3858-3872 ◽  
Author(s):  
Haishun Deng ◽  
Qingchun Wang ◽  
Haifeng Wang ◽  
Chuanli Wang
Keyword(s):  
Relative Motion ◽  
Relative Velocity ◽  
Piston Pump ◽  
Shaft Speed ◽  
Axial Piston Pump ◽  
Double Row ◽  
Swash Plate ◽  
Spherical Bearing ◽  
Pump Shaft ◽  
Axial Piston

Based on the external compaction return mechanism of a balanced double-row axial piston pump and the vector coordinate transformation principle, a mathematical model of the relative motion relation within the external return spherical bearing pair was built. The influence of slant inclination of the external swash plate and of pump shaft rotating speed and eccentricity on the relative motion trail, movement speed and acceleration was analysed. The relative motion velocity and acceleration between external retainer plate and external spherical hinge, at top and bottom dead centres, were discussed. By increasing the slant inclination of the external swash plate, the relative motion trail increased correspondingly, leading to a larger size of the pump integral structure. The relative speed and acceleration increased with the pump shaft speed and the slant inclination of the external swash plate, leading to a larger fluctuation of the slipper pair oil film. The increase of eccentricity slightly influenced the relative velocity and acceleration along the x-axis, without significantly increasing the fluctuation of the slipper pair oil film. Increasing the pump shaft speed, the external swash plate slant inclination and the eccentricity all caused fluctuations in the relative velocity and acceleration along the y- and z-axes, deepening the grinding crack on the compaction surface of the external retainer plate. In case of eccentricity and a 0° rotation angle of the principal axis, the related acceleration of the radial friction surface of the retainer plate showed the largest fluctuation amplitude, and a scratch could easily occur.

Power Loss of Slipper within Axial Piston Pump

2015 ◽  
Vol 779 ◽  
pp. 3-12
Author(s):  
Ze Bo Wang ◽  
Ji Hai Jiang ◽  
Yi Sun
Keyword(s):  
Power Loss ◽  
Friction Pair ◽  
Piston Pump ◽  
Axial Piston Pump ◽  
Factors Affecting ◽  
Friction Power ◽  
Swash Plate ◽  
Model Of Friction ◽  
Friction Surfaces ◽  
Axial Piston

The pair between slipper and swash-plate is an important friction pair in the axial piston pump. Due to quick relative velocity, alternating load, numerous slippers, and high contact pressure between the friction surfaces, the wear-out and fatigue failure constantly occurs, which is one of the key factors affecting reliability of the piston pump. It is of fundamental significance to investigate the mechanism of slipper power loss and to find an appropriate method to improve the lubrication of the slipper. Here, the model of friction power loss between slipper and swash-plate is established, and the friction power loss between slipper and swash-plate is solved and comparatively analysed. Finally, the correctness of theoretical analysis and simulation results are verified by experiments.

The Control Torque on the Swash Plate of an Axial-Piston Pump Utilizing Piston-Bore Springs

1999 ◽  
Vol 123 (3) ◽  
pp. 471-478 ◽  
Author(s):  
Noah D. Manring ◽  
Fikreadam A. Damtew
Keyword(s):  
Mechanical Analysis ◽  
Plate Motion ◽  
Cylinder Block ◽  
Normal Operation ◽  
Favorable Result ◽  
Control Torque ◽  
Restoring Force ◽  
Pump Design ◽  
Swash Plate ◽  
Spring Force

This research begins by presenting a nontraditional pump design which utilizes a piston-bore spring. The piston-bore spring is included in this design for the purpose of holding the cylinder block against the valve plate and for forcing the pistons in the negative x-direction. By forcing the pistons in this direction, the piston-bore spring also assists in holding the slippers against the swash plate during the normal operation of the pump. Though these advantages of the design may be readily seen by inspection, it is not obvious how the control torque on the swash plate is effected by the piston-bore spring nor is it obvious how one would go about designing the spring to produce a favorable result. To clarify the benefit of this design, a mechanical analysis is conducted to describe the effect of the spring on the control torque itself. As a result of this analysis, a general equation which describes the swash-plate motion is presented. Within this equation, it may be seen that the spring force provides a restoring force on the swash plate which tends to stabilize the design. The piston-bore spring is also shown to be capable of eliminating the cross-over from a stroke increasing swash-plate torque to a stroke decreasing swash-plate torque. By eliminating this cross over, the backlash in the pump control (which is commonly observed in practice) can be prevented.

Complex Pressure Fluctuations and Vibrations in a Pump-Water Tunnel System

2003 ◽  
Author(s):  
Shijie Guo ◽  
Yoshiyuki Maruta ◽  
Hidenobu Okamoto ◽  
Hideki Kanno ◽  
Kiyonori Sato
Keyword(s):  
Natural Frequencies ◽  
Pressure Fluctuations ◽  
Axial Flow ◽  
Strong Relationship ◽  
Acoustic Resonance ◽  
Dominant Frequency ◽  
Torsional Vibrations ◽  
Rotating Speed ◽  
Pump Station ◽  
Pump Shaft

This paper reports on the complex phenomena of pressure fluctuations and vibrations in a large-capacity drainage pump station. Significant pressure fluctuations were observed in suction water tunnels when an axial flow pump was operated without an actual head at some blade angles. To identify the causes, investigations were done by measuring acoustic natural frequencies and pressure fluctuations in the tunnels, lateral and torsional vibrations of the pump shaft, and pressure fluctuations of the oil in the hydraulic system to control the blade angle. The measurements were taken for different blade angles, rotating speeds, as well as acoustic natural frequencies. The natural frequency was changed by inserting air into the suction tunnels with a compressor and by setting air bags. The results showed that acoustic resonance occurred in the tunnels, but it was not a simple resonance. The dominant frequency, which was neither the blade passing frequency nor its higher harmonics, depended on rotating speed in the reverse way: it decreased when rotating speed increased, and vice versa. Pressure fluctuations in the water tunnels and lateral/torsional vibrations of the pump shaft had a strong relationship. However, they had different dominant frequencies and occurred at different blade angles. Several measurements were made in different seasons and it was found that the phenomena were season-dependent (dependent on quality of water). The causes are discussed. It is believed that the excitation source was vortex shedding from the blades, which locked into the acoustic resonance in the water tunnels via vibration of the blades.

scholarly journals Climbing parrots achieve pitch stability using forces and free moments produced by axial-appendicular couples

2021 ◽  
Author(s):  
Lindsey L. Reader ◽  
David R. Carrier ◽  
Franz Goller ◽  
Michael R. Isaacs ◽  
Alexis Moore Crisp ◽  
...  
Keyword(s):  
Contact Point ◽  
Natural Habitat ◽  
Three Dimensional ◽  
Large Radius ◽  
Pitching Moment ◽  
Free Moments ◽  
Contact Points ◽  
Multiple Contacts ◽  
Discrete Contact ◽  
Free Moment

During vertical climbing, the gravitational moment tends to pitch the animal's head away from the climbing surface and this may be countered by 1) applying a correcting torque at a discrete contact point, or 2) applying opposing horizontal forces at separate contact points to produce a free moment. We tested these potential strategies in small parrots with an experimental climbing apparatus imitating the fine branches and vines of their natural habitat. The birds climbed on a vertical ladder with four instrumented rungs that measured three-dimensional force and torque, representing the first measurements of multiple contacts from a climbing bird. The parrots ascend primarily by pulling themselves upward using the beak and feet. They resist the gravitational pitching moment with a free moment produced by horizontal force couples between the beak and feet during the first third of the stride and the tail and feet during the last third of the stride. The reaction torque from individual rungs did not counter, but exacerbated the gravitational pitching moment, which was countered entirely by the free moment. Possible climbing limitations were explored using two different rung radii, each with low and high friction surfaces. Rung torque was limited in the large-radius, low-friction condition, however, rung condition did not significantly influence free moments produced. These findings have implications for our understanding of avian locomotor modules (i.e., coordinated actions of the head-neck, hindlimbs, and tail), the use of force couples in vertical locomotion, and the evolution of associated structures.

The Relative Motion Between the Ball Guide and Slipper Retainer Within an Axial-Piston Swash-Plate Type Hydrostatic Pump

1999 ◽  
Vol 121 (3) ◽  
pp. 518-523 ◽  
Author(s):  
Noah D. Manring
Keyword(s):  
Relative Motion ◽  
Relative Velocity ◽  
Contact Point ◽  
Cone Angle ◽  
Operating Speed ◽  
Cartesian Coordinates ◽  
Swash Plate ◽  
Design Value ◽  
Axial Piston ◽  
Plate Type

The objectives of this research are to develop the equations that describe the relative motion between the ball guide and the slipper retainer within an axial-piston swash-plate type hydrostatic pump. Using a relationship between spherical and Cartesian coordinates, a contact point between the ball guide and the retainer is identified and matched for an observer on the ball guide and an observer on the retainer. Once a generic contact point is established, the position of a fixed particle on the ball guide is subtracted from the position of a particle on the retainer. The trajectory of this particle relative to the fixed particle on the ball guide is then used to describe the teardrop wear patterns that are expected to appear on the ball guide. These wear patterns are confirmed by experiments. Next, the velocity of a particle on the ball guide is subtracted from the velocity of a particle on the retainer at the contact point. Based upon this result it is shown that a relative velocity between the ball guide and the retainer is always maintained for a nonzero swash-plate angle and that the minimum relative velocity between the retainer and the ball guide may be increased by increasing one or all of the following: the design value of the retainer cone-angle, the radius of the ball guide, the operating speed of the pump, or the pump swash-plate angle.

A novel planetary thread roller bearing: Design and analysis of load characteristic

2020 ◽  
pp. 1-7
Author(s):  
Shicheng Zheng ◽  
Yongling Fu ◽  
Deyi Wang ◽  
Junlin Pan ◽  
Linjie Li ◽  
...  
Keyword(s):  
Axial Load ◽  
Contact Point ◽  
Roller Bearing ◽  
Weight Ratio ◽  
Friction Torque ◽  
Installation Space ◽  
Load Rating ◽  
Ratio Requirement ◽  
Rotating Speed ◽  
Load Carrying

Abstract A novel planetary thread roller bearing (PTRB) was proposed in this paper based on Herz theory combined with multiple principles (e.g. equivalent steel ball, multi-point meshing and power dividing). A significant improvement in load-carrying capacity, comparing the current bearing, was achieved and thus providing a new option for the advanced equipment with high thrust-to-weight ratio requirement. The newly proposed PTRB exhibited a 83 % increase in dynamic axial load rating while a comparable static axial load rating comparing with the thrust ball bearing with a comparable size. In addition, the relationship between friction torque and bearing rotating speed, contact point number and axial load was discussed. It was found that, given a proper installation space, increasing the thread roller number could not only significantly improve the axial load rating of PTRB, but also reduce the friction torque. Furthermore, the working efficiency of the new PTRB was constantly higher than 97 %. A self-degradation operation was achieved by the system when some thread rollers were stuck, which improved the system fault tolerance. Finally, friction torque tests were performed on the self-developed test instrument. The results showed a good agreement with the theoretical analysis.

The Influence of Damping Coefficient on Vibration Characteristic of a Rub-Impact Rotor under Axial Thrust

2010 ◽  
Vol 20-23 ◽  
pp. 358-363
Author(s):  
Xue Li An ◽  
Dong Xiang Jiang ◽  
Chao Liu ◽  
Ming Hao Zhao
Keyword(s):  
Contact Point ◽  
Rotor System ◽  
System Response ◽  
Axial Thrust ◽  
Chaotic Motions ◽  
Rotating Speed ◽  
Impact Theory ◽  
Tangential Forces ◽  
The Impact ◽  
Rubbing Condition

A model of a rub-impact rotor system under axial thrust is established based on the classic impact theory and analyzed by the Lagrangian dynamics and bifurcation theories. The rubbing condition is modeled using the impact-contact idealization, which consists of normal and tangential forces at the rotor-to-stator contact point. The effects of lateral damping and rotor rotating speed on the rotor system response are investigated in detail. It is demonstrated that the system goes through an extraordinary route to bifurcation. Periodic, quasi-periodic and chaotic motions are found as the system parameters change.

scholarly journals Characteristics of Hydraulic and Electric Servo Motors

Actuators ◽  
2022 ◽  
Vol 11 (1) ◽  
pp. 11
Author(s):  
Sayako Sakama ◽  
Yutaka Tanaka ◽  
Akiya Kamimura
Keyword(s):  
Mechanical Systems ◽  
Electric Motors ◽  
Rotating Speed ◽  
Brushless Dc ◽  
Swash Plate ◽  
Hydraulic Motors ◽  
Power Rate ◽  
Hydraulic Servo ◽  
Improved Performance ◽  
Axial Piston

Until the 1970s, hydraulic actuators were widely used in many mechanical systems; however, recently, electric motors have become mainstream by virtue of their improved performance, and hydraulic motors have largely been replaced by electric motors in many applications. Although this trend is expected to continue into the future, it is important to comprehensively evaluate which motor is most suitable when designing mechanical systems. This paper presents the results of a survey of the performance of electric and hydraulic servo motors and aims to provide quantitative data that can be used as a reference for selecting appropriate motors. We surveyed AC, AC direct, brushless DC, and brushed DC electric motors and swash plate-type axial piston, bent axis-type axial piston, crank-type radial piston, and multistroke-type radial piston hydraulic motors. Performance data were collected from catalogs and nonpublic data. We compared and evaluated the characteristics of these diverse servo motors using indexes such as torque, rotating speed, output power, power density, and power rate.

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