Speed-Variable Switched Differential Pump System for Direct Operation of Hydraulic Cylinders

2015 ◽  
Author(s):  
Lasse Schmidt ◽  
Daniel B. Roemer ◽  
Henrik C. Pedersen ◽  
Torben O. Andersen
Keyword(s):  
Dynamic Properties ◽  
Main Idea ◽  
Chamber Pressure ◽  
Gear Pump ◽  
Hydraulic Systems ◽  
Direct Drive ◽  
Motion Direction ◽  
Pump System ◽  
Compression Flow ◽  
Gear Pumps

Efforts to overcome the inherent loss of energy due to throttling in valve driven hydraulic systems are many, and various approaches have been proposed by research communities as well as the industry. Recently, a so-called speed-variable differential pump was proposed for direct drive of hydraulic differential cylinders. The main idea was here to utilize an electric rotary drive, with the shaft interconnected to two antiparallel fixed displacement gear pumps, to actuate a differential cylinder. With the design carried out such that the area ratio of the cylinder matches the displacement ratio of the two gear pumps, the throttling losses are confined to cross port leakage in the cylinder and leakage of the pumps. However, it turns out that the volumetric pump losses and the pressure dynamics of the cylinder and connecting pipes may cause pressure increase- or decrease in the cylinder chambers, which may seriously influence the dynamics and hence the performance during operation. This paper presents an analysis of these properties, and a redesign of the hydraulic system concept is proposed. Here the area- and displacement ratios are deliberately mismatched, causing inherent pressure build-up or cavitation in the return chamber, depending on the direction of motion. In order to avoid cavitation, a third gear pump is introduced, which provides a flow in the relevant cylinder chamber in one direction of motion, while operating in idle mode in the opposite motion direction. Together with two 2/2 way proportional valves, this design allows to control the lower chamber pressure levels, throttling excess compression flow to tank. The resulting design introduces additional losses due to throttling of excess compression flow, but also improves the dynamic properties of the system significantly. The proposed features are verified by comparison with the original pump concept and a conventional valve concept. Furthermore, significant improvement in energy efficiency is demonstrated under certain load conditions.

scholarly journals Visualization research on the influence of an ultrasonic degassing system on the operation of a hydraulic gear pump

2018 ◽  
Vol 211 ◽  
pp. 03005 ◽  
Author(s):  
Piotr Antoniak ◽  
Jarosław Stryczek ◽  
Michał Banaś ◽  
Oleksandr Lyhovskyi ◽  
Ihor Gryshko ◽  
...  
Keyword(s):  
High Speed ◽  
Theoretical Description ◽  
Working Fluid ◽  
Operating Parameters ◽  
Gear Pump ◽  
Hydraulic Systems ◽  
Chemical Methods ◽  
Physical Methods ◽  
Working Medium ◽  
Gear Pumps

Gear pumps make a group of the most popular hydraulic energy generators. Research and development works concerning those units have been going on for decades, and thanks to them gear pumps feature very good operating parameters. However, even well-designed gear pumps will not work properly if the physical properties of the working fluid are incorrect. One of such properties is compressibility of the fluid, which largely depends on the amount of gas dissolved in the medium. For this reason, the aim is to reduce the amount of gas dissolved in the working medium. It can be done using both chemical and physical methods. Because chemical methods can affect the chemical composition of the working fluid, it is the physical methods that are usually used in hydraulic systems. This paper presents preliminary visualization research into the influence of an ultrasonic degassing system on the operation of a hydraulic gear pump. Apart from that, operation of such a system and its theoretical impact on the work of the gear pump is discussed Experimental study, using a high-speed camera, was carried out in order to verify the theoretical description.

scholarly journals Psychoacoustic Evaluation of Hydraulic Pumps

2021 ◽  
Vol 13 (13) ◽  
pp. 7320
Author(s):  
Tobias Pietrzyk ◽  
Markus Georgi ◽  
Sabine Schlittmeier ◽  
Katharina Schmitz
Keyword(s):  
Sound Pressure ◽  
Paired Comparison ◽  
Hydraulic Drive ◽  
Operating Parameter ◽  
Gear Pump ◽  
Hydraulic Systems ◽  
Hydraulic Pump ◽  
Listening Tests ◽  
Internal Gear ◽  
Axial Piston

In this study, sound measurements of an axial piston pump and an internal gear pump were performed and subjective pleasantness judgements were collected in listening tests (to analyze the subjective pleasantness), which could be seen as the inverse of the subjective annoyance of hydraulic drives. Pumps are the dominant sound source in hydraulic systems. The noise generation of displacement machines is subject of current research. However, in this research only the sound pressure level (SPL) was considered. Psychoacoustic metrics give new possibilities to analyze the sound of hydraulic drive technology and to improve the sound quality. For this purpose, instrumental measurements of the acoustic and psychoacoustic parameters are evaluated for both pump types. The recorded sounds are played back to the participants in listening tests. Participants evaluate them regarding the subjective pleasantness by means of paired comparison, which is an indirect scaling method. The dependence of the subjective pleasantness on speed and pressure was analyzed for both pump types. Different regression analyses were carried out to predict the subjectively perceived pleasantness or annoyance of the pumps. Results show that a lower speed is the decisive operating parameter for reducing both the SPL and the annoyance of a hydraulic pump.

Response Prediction and Dynamic Substructuring for Coupled Structures in the Frequency Domain

2020 ◽  
Vol 36 (6) ◽  
pp. 867-879
Author(s):  
X. H. Liao ◽  
W. F. Wu ◽  
H. D. Meng ◽  
J. B. Zhao
Keyword(s):  
Frequency Response ◽  
Response Function ◽  
Frequency Response Function ◽  
Dynamic Properties ◽  
Main Idea ◽  
Prediction Method ◽  
Response Prediction ◽  
Synthesis Methods ◽  
Dynamic Substructuring ◽  
Coupled Structures

ABSTRACTTo evaluate the dynamic properties of a coupled structure based on the dynamic properties of its substructures, this paper investigates the dynamic substructuring issue from the perspective of response prediction. The main idea is that the connecting forces at the interface of substructures can be expressed by the unknown coupled structural responses, and the responses can be solved rather easily. Not only rigidly coupled structures but also resiliently coupled structures are investigated. In order to further comprehend and visualize the nature of coupling problems, the Neumann series expansion for a matrix describing the relation between the coupled and uncoupled substructures is also introduced in this paper. Compared with existing response prediction methods, the proposed method does not have to measure any forces, which makes it easier to apply than the others. Clearly, the frequency response function matrix of coupled structures can be derived directly based on the response prediction method. Compared with existing frequency response function synthesis methods, it is more straightforward and comprehensible. Through demonstration of two examples, it is concluded that the proposed method can deal with structural coupling problems very well.

Computer Prediction of Cyclic Excitation Sources for an External Gear Pump

1985 ◽  
Vol 199 (3) ◽  
pp. 175-180 ◽  
Author(s):  
K Foster ◽  
R Taylor ◽  
I M Bidhendi
Keyword(s):  
Computer Program ◽  
Gear Pump ◽  
Computer Prediction ◽  
Pressure Distributions ◽  
External Gear Pumps ◽  
Theoretical Predictions ◽  
Gear Pumps ◽  
External Gear Pump

A description is given of a computer program for investigating the performance of the external gear pumps under varying conditions with the special emphasis on the examination of pressure distributions within the pump, i.e. excitation forces for the vibration of the pump case and the variation in flow generated by the pump. Measurements are presented for the variation with time of tooth space pressure and the results are compared with the theoretical predictions from the computer program.

Experimental Investigation of Flowrate Irregularity in Rotary Gear Pumps

1992 ◽  
Author(s):  
G. Mimmi
Keyword(s):  
Experimental Investigation ◽  
Flow Rate ◽  
Experimental Tests ◽  
Periodic Variation ◽  
Experimental Results ◽  
Gear Pump ◽  
Gear Pumps ◽  
Hot Film ◽  
Instantaneous Flow Rate ◽  
External Gear Pump

Abstract In a previous paper the author proposed a method to reduce the periodic variation in flow rate for an external gear pump. To verify the experimental results, a series of experimental tests on a expressly realized gear pump, was carried out. The pump was equipped with relieving grooves milled into the side plates. The tests were done on a closed piping specifically realized and equipped for measuring the instantaneous flow rate of the fluid through a wedge-shaped hot film probe.

WHICH WILL WIN IN THE GEAR PUMP TECHNOLOGY

2013 ◽  
Vol 37 (1) ◽  
pp. 129-134 ◽  
Author(s):  
Hai-Lin Zhu ◽  
Jun Pan ◽  
Min Zou ◽  
Hong-Nen Wu ◽  
Xingpei Qin
Keyword(s):  
Working Life ◽  
Radial Pressure ◽  
Radial Force ◽  
Gear Pump ◽  
Ring Gear ◽  
Flow Pulsation ◽  
Gear Pumps ◽  
New Type ◽  
Flexible Ring ◽  
Short Working

There exist three major problems in current gear pumps. They are unbalanced radial force, big excessive flow pulsation and short working life. In order to solve the problems above, a new type of gear pump with flexible ring gear is introduced. Pumping action is achieved through meshing between a flexible ring gear and a rigid external gear. Thus radial pressure forces are hydraulically balanced and the volumetric displacement is doubled for the new pump.

A gear pump based on harmonic gear drive

2013 ◽  
Vol 227 (12) ◽  
pp. 2844-2848 ◽  
Author(s):  
Hai-Lin Zhu ◽  
Peng Ning ◽  
Min Zou ◽  
Xingpei Qin ◽  
Jun Pan
Keyword(s):  
Service Life ◽  
Fluid Pressure ◽  
Gear Pump ◽  
Flow Pulsation ◽  
Flow Ripple ◽  
Gear Drive ◽  
Mutual Engagement ◽  
Gear Pumps ◽  
New Type ◽  
Total Discharge

Aimed at solving the problems of radial fluid pressure imbalance, bigger flow ripple and shorter service life that exists in traditional gear pumps, a new type of gear pump based on the principle of harmonic gear drive is put forth, where the function for pumping fluid is achieved by mutual engagement between flexible gear and rigid gear. The structural composition, principle and features of the new gear pump are described in this article. The new pump has two higher pressure cavities arranged symmetrically, which counteracts the fluid pressure and the pump could work longer. Its displacement is two times that of the conventional gear pump and the total discharge is bigger. Flow pulsation, vibration and noise in the new pump are evidently diminished, which make the operation smooth. The new gear pump has superiority in performance and could guide the development in gear pump technology.

Modeling and CFD Analyses of Gear Pump in OpenFOAM

2019 ◽  
Author(s):  
G. Shoukat ◽  
Kamran Siddique ◽  
M. Sajid
Keyword(s):  
Power Flow ◽  
Experimental Studies ◽  
Research Area ◽  
Peak Performance ◽  
Gear Pump ◽  
Numerical Studies ◽  
Gear Pumps ◽  
Cfd Analyses ◽  
Dynamic Meshing ◽  
Pressure Output

Abstract Turbomachinery plays a key role in process and manufacturing industries. The interplay between power, flow rates and pressure output remain an interesting research area. To support specific processes in the industry, each pump or compressor must be fine-tuned for peak performance. As trend shifts from large organizations to entrepreneurial startups, spending significant costs on licensing of commercially available CFD softwares becomes unfeasible. This paper investigates the use of OpenFOAM – open source CFD package towards the analysis of gear pumps. The solution employs dynamic meshing and snappyHexMesh library in a single study. To validate the numerical model developed under OpenFoam’s environment, experimental studies were carried out. The pressure output of the pump was measured at four different RPMs — 200, 250, 300 and 400. An excellent agreement between experimental and numerical studies was seen at relatively higher RPMs. The numerical studies further explored the pulsating flow, recorded the variation between a constant maximum and minimum pressure value for each RPM. The variation in pressure was observed to increase at higher RPMs. The agreement between experimental and numerical findings established the utility of OpenFoam in investigating pump action.

Methodology for the Evaluation of Gear Pump Performance

2020 ◽  
Author(s):  
Logan T. Williams
Keyword(s):  
Empirical Data ◽  
Pressure Rise ◽  
Operating Conditions ◽  
Volumetric Efficiency ◽  
Fluid Viscosity ◽  
Gear Pump ◽  
Pump Performance ◽  
Pump Speed ◽  
Multiple Parameters ◽  
Gear Pumps

Abstract Currently, most performance curves of gear pumps present volumetric efficiency as a function of one or more operating conditions. However, the nature of gear pumps is that volumetric efficiency is dependent on pump speed, pump pressure rise, and fluid viscosity. This dependency on multiple parameters impedes direct comparisons between pumps tested at disparate operating conditions or on different testbeds. A new method has been developed that formulates the volumetric efficiency as a function of a single parameter that captures pump speed, pressure, and fluid viscosity. The characteristics of the pump is then captured by curve fitting two constants to empirical data. This method allows extrapolation of pump performance beyond empirical data and direct comparison of the volumetric efficiency curves of two pumps tested under disparate conditions within a single plot. This work describes the analytical derivation of the methodology and the empirical data used for validations. Additionally, several possible applications of this method are presented.

scholarly journals A Study on Noise Reduction of Gear Pumps of Wheel Loaders Based on the ICA Model

2019 ◽  
Vol 16 (6) ◽  
pp. 999 ◽  
Author(s):  
Panling Huang ◽  
Liang Xu ◽  
Chuan Luo ◽  
Jianchuan Zhang ◽  
Feng Chi ◽  
...  
Keyword(s):  
Fourier Transform ◽  
Fast Fourier Transform ◽  
Noise Reduction ◽  
Noise Level ◽  
Gear Pump ◽  
Noise Sources ◽  
Environmentally Sustainable ◽  
Gear Pumps ◽  
Mixed Noise ◽  
Wheel Loaders

In order to reduce the noise level of wheel loaders caused by gear pumps and realize environmentally sustainable development, the noise generation mechanism of a gear pump was studied, and the influence of flow pulsation and gear impact on noise was analyzed. In order to reduce the interference of other noise sources on the noise level of the gear pump, a noise test rig was established. The mixed noise signals obtained from the rig test were separated using the ICA model. The ICA model includes the following algorithms: The fast Fourier transform (FFT), independent component analysis (ICA) and inverse fast Fourier transform (IFFT). Some theories about the influence of the teeth number and teeth profile on noise were analyzed by theory and simulation. A noise reduction strategy was proposed by increasing the teeth numbers and modifying the teeth profile of the gear pump. The tests results showed that the noise values of the external and the driver’s ear of the wheel loader were reduced to 1 and 2.2 dB (A), respectively. This proves the effectiveness of the optimization scheme of gear pump noise reduction.

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