A thermal hydraulic model based on the lumped parameter method is presented to analyze the load-carrying capacity of a slipper pair in an aviation axial-piston pump under specified operating conditions. Both theoretic...A thermal hydraulic model based on the lumped parameter method is presented to analyze the load-carrying capacity of a slipper pair in an aviation axial-piston pump under specified operating conditions. Both theoretical and experimental results are presented to demonstrate the validity of the thermal hydraulic model. The results illustrate that the squeezing force and thermal wedge bearing force are the main factors that affect the film thickness and load-carrying capacity.At high oil temperature and high load pressure, the film thickness decreases with increasing clamping force due to a combined action of the squeezing bearing force and the thermal wedge bearing force, but the load-carrying capacity will increase. An increase of the film thickness is proven to be beneficial under high shaft rotational speed but especially dangerous as it strongly increases the ripple amplitude of the film thickness, which leads to decreasing the load-carrying capacity. The structural parameters of the slipper can be optimized to achieve desired performance, such as the slipper radius ratio and orifice length diameter ratio. To satisfy the requirement of the load-carrying capacity, the slipper radius ratio should be selected from 1.4 to 1.8, and the orifice length diameter ratio should be selected from 4 to 5.展开更多
A computational fluid dynamics （CFD） simulation method based on 3-D Navier Stokes equation and Arbitrary Lagrangian Eulerian （ALE） method is presented to analyze the grooved slip- per performance of piston pump. T...A computational fluid dynamics （CFD） simulation method based on 3-D Navier Stokes equation and Arbitrary Lagrangian Eulerian （ALE） method is presented to analyze the grooved slip- per performance of piston pump. The moving domain of grooved slipper is transformed into a fixed reference domain by the ALE method, which makes it convenient to take the effects of rotate speed, body force, temperature, and oil viscosity into account. A geometric model to express the complex structure, which covers the orifice of piston and slipper, vented groove and the oil film, is constructed. Corresponding to different oil film thicknesses calculated in light of hydrostatic equilibrium theory and boundary conditions, a set of simulations is conducted in COMSOL to analyze the pump characteristics and effects of geometry （groove width and radius, orifice size） on these characteristics. Furthermore, the mechanics and hydraulics analyses are employed to validate the CFD model, and there is an excellent agreement between simulation and analytical results. The simulation results show that the sealing land radius, orifice size and groove width all dramatically affect the slipper behavior, and an optimum tradeoff among these factors is conducive to optimizing the pump design.展开更多
The interface between the slipper/swash plate is one of the most important frication pairs in axial piston pumps.The test of this interface in a real pump is very challenging.In this paper,a novel pump prototype is de...The interface between the slipper/swash plate is one of the most important frication pairs in axial piston pumps.The test of this interface in a real pump is very challenging.In this paper,a novel pump prototype is designed and a test rig is set up to study the dynamic lubricating performance of the slipper/swash-plate interface in axial piston machines.Such an experimental setup can simulate the operating condition of a real axial piston pump without changing the relative motion relationship of the interfaces.Considering the lubricant oil film thickness as the main measurement parameter,the attitude of the slipper under the conditions of different load pressure,rotation speed and charge pressure are studied experimentally.After the test,the wear state of the swash plate is observed.According to the friction trace on the surface of the swash plate,the prediction for the attitude of the slipper and the zone easy to wear are verified.展开更多
This study investigates tribological performance of MoS2 coating on slipper pair in axial piston pump.Firstly,the MoS2 coating on the surface of slipper pair was prepared by atmospheric plasma spraying treatment techn...This study investigates tribological performance of MoS2 coating on slipper pair in axial piston pump.Firstly,the MoS2 coating on the surface of slipper pair was prepared by atmospheric plasma spraying treatment technology.Secondly,the tribological characteristics of slipper pair under various working conditions were evaluated on ring-on-block tester in oil lubrication.The original and worn surfaces of the specimens were analyzed with scanning electron microscope and energy dispersive spectrometer,and then the wear morphologies of the MoS2 coatings were imaged by X-ray photoelectron spectroscopy.The experimental results showed that the friction coefficients of Cu-based materials with MoS2 coating decreased by about 0.05 at 800 N.Especially,when the external load was set to 800 N,the wear rate of the ZY331608 decreased by about 16.4%after the substrates were treated by the MoS2 coating,which exhibited excellent anti-friction and wear resistance.The formation of the MoS2 lubricating film could be classified into four stages,including the initial friction stage,anchoring stage of MoS2 on friction surface,covering stage of the sliding surface by MoS2 and the formation stage of MoS2 film.The dominating wear mechanisms of Cu-based materials with MoS2 coating were adhesive wear and abrasive wear accompanied with oxidative wear.展开更多
Pressure-flow analytical formulas of lubrication film of slipper pairs on camshaft connecting rod type low speed high torque(LSHT)hydraulic motors are put forward.The bottom surface of slipper pairs is rectangle,and t...Pressure-flow analytical formulas of lubrication film of slipper pairs on camshaft connecting rod type low speed high torque(LSHT)hydraulic motors are put forward.The bottom surface of slipper pairs is rectangle,and the effect of squeeze flow and pressure differential flow is considered.The dynamic process of lubrication film formation through squeezing is numerically studied by computer simulation.Effects of supply pressure,initial lubrication film thickness,velocity damping coefficient,loading impact and gravity,etc are studied.Advantages of novel slipper pairs with large oil cavity area are pointed out.展开更多
Oil leakage between the slipper and swash plate of an axial piston pump has a significant effect on the efficiency of the pump.Therefore,it is extremely important that any leakage can be predicted.This study investiga...Oil leakage between the slipper and swash plate of an axial piston pump has a significant effect on the efficiency of the pump.Therefore,it is extremely important that any leakage can be predicted.This study investigates the leakage,oil film thickness,and pocket pressure values of a slipper with circular dimples under different working conditions.The results reveal that flat slippers suffer less leakage than those with textured surfaces.Also,a deep learning-based framework is proposed for modeling the slipper behavior.This framework is a long short-term memory-based deep neural network,which has been extremely successful in predicting time series.The model is compared with four conventional machine learning methods.In addition,statistical analyses and comparisons confirm the superiority of the proposed model.展开更多
A novel dynamic model describing the slipper posture of the swash plate in axial piston pumps is proposed, taking into account the hydrodynamic and squeezing effects, which involves three degrees of freedom. The varia...A novel dynamic model describing the slipper posture of the swash plate in axial piston pumps is proposed, taking into account the hydrodynamic and squeezing effects, which involves three degrees of freedom. The variation in the lubricating film thickness and the slipper tilt are accurately calculated. The influence of hydrodynamic effects and charging pressure on the slipper lubrication is discussed. The minimum film thickness, the overturning angle and the azimuth angle are obtained.Then, the trajectory of minimum thickness on the friction surface of the swash plate is predicted, the accuracy of which can be verified with the abrasion distribution of an actual swash plate. Research results can predict the durability and provide theoretical help for the design of the slipper.展开更多
In order to improve lubricating characteristics of slippers in an axial piston pump, the combining center cavity slipper approach was proposed based on slipper shape and moving characteristic. The cylindrical coordina...In order to improve lubricating characteristics of slippers in an axial piston pump, the combining center cavity slipper approach was proposed based on slipper shape and moving characteristic. The cylindrical coordinate was used in the lubricant area and mesh was made. The blockweight approach was implemented to deal with non-coincidence of mesh and shallow recess border in numerical method. The finite control volume method was applied in calculating pressure distribution. The flow conservation equation and film thickness model were resolved through Gauss-Siedel relaxation iteration. The calculation and analysis results indicate that compared to the slipper （1） slip- per pressure distribution is improved; （2） hydrodynamic pressure of the combining slipper is greatly increased; （3） inclining degree is greatly reduced; （4） negative pressure in lubricant film disappear. So the combining center cavity slipper is lubricated better.展开更多
he power density of axial piston pumps can greatly benefit from increasing the speed level.However,traditional slippers in axial piston pumps are exposed to continuous sliding on the swash plate,suffering from serious...he power density of axial piston pumps can greatly benefit from increasing the speed level.However,traditional slippers in axial piston pumps are exposed to continuous sliding on the swash plate,suffering from serious wear at high rotational speeds.Therefore,this paper presents a new integrated slipper retainer mechanism for high-speed axial piston pumps,which can avoid direct contact between the slippers and the swash plate and thereby eliminate slipper wear under severe operating conditions.A lubrication model was developed for this specific slipper retainer mechanism,and experiments were carried out on a pump prototype operating at high rotational speed up to 10000 r/min.Experimental results qualitatively validated the theoretical model and confirmed the effectiveness of the new slipper design.展开更多
Improving the carrying ability of oil film between slipper and swash plate and reducing the partial abrasion of slipper are important to improve the service life and reliability of axial piston pump.In this paper,a nu...Improving the carrying ability of oil film between slipper and swash plate and reducing the partial abrasion of slipper are important to improve the service life and reliability of axial piston pump.In this paper,a numerical simulation model was developed for slipper/swash-plate friction pair based on the elastohydrodynamic theory.The dynamic micro-motion and pressure distribution of slipper were analyzed and it was pointed out that the tilt of slipper was the main reason for its partial abrasion.The simulations about the slippers with different slopes on the outer edge of the sealing belt showed that the partial abrasion could reduce the carrying ability and increase the leakage of the slipper/swash-plate pair.The proper slope on the inner edge helped to improve the carrying ability and reduce the leakage of slipper.The experimental tests were in accord with the simulation results to a great extent,showing that the simulation model had a high accuracy and could be applied to the design and optimization of slipper,and that the slipper with optimal inner slope provided an encouraging method to improve the efficiency and reliability of axial piston pump.展开更多
High-pressure axial piston pumps operate in high-speed and high-pressure environments. The contact state of the slipper against the swashplate can easily change from an oil film lubrication to a mixed oil film/asperit...High-pressure axial piston pumps operate in high-speed and high-pressure environments. The contact state of the slipper against the swashplate can easily change from an oil film lubrication to a mixed oil film/asperity contact, or even dry friction. To improve the dry friction performance of slipper pairs and to avoid their potentially rapid failure, this study examined the effects of material matching on the dry friction performance of the slipper pair for high-pressure axial piston pumps. A FAIAX6 friction and wear tester was developed, and the dry friction coefficients of the slipper pairs matched with different materials were studied using this tester. Based on the thermo-mechanical coupling of the slipper pair with the working process, the contact surface temperatures of the slipper pairs matched with different materials were calculated and analyzed for the same working conditions. Following this, the effects of the material properties on the temperature increase at the slipper sliding contact surfaces were revealed. The reliabilities of the temperature calculations and analysis results were verified through orthogonal tests of slipper pairs matched with different materials. The results indicate that the influence of the material density on the friction coefficient is greater than that of the Poisson's ratio or the elastic modulus, and that the slipper material chosen should have a high thermal conductivity, low density, and low specific heat, whereas the swashplate material should be high in specific heat, density, and thermal conductivity;in addition, the slipper pair should be a type of hard material to match the type of soft material applied;that is, the hardness of the swashplate material should be greater than that of the slipper material.展开更多
A crosshead slipper-guide system,which bears a significant thrust force,is an essential friction pair in low-speed marine diesel engines.Owing to the low moving speed of the crosshead slipper during engine startup,it ...A crosshead slipper-guide system,which bears a significant thrust force,is an essential friction pair in low-speed marine diesel engines.Owing to the low moving speed of the crosshead slipper during engine startup,it is difficult to form good hydrodynamic lubrication between the crosshead slipper and guide.Therefore,a detailed analysis of the crosshead slipper during engine startup is needed.In this study,a new transient tribo-dynamic model for a crosshead slipper during the engine startup process is presented.The model consists of a mixed lubrication model of the crosshead slipper-guide and dynamic models of the piston assembly,crosshead assembly,connecting rod,and crankshaft.The tribo-dynamic performances of the crosshead slipper during startup and under the rated conditions were simulated and compared.The results show that the tribo-dynamics of the crosshead slipper during the startup process are significantly different from those under the rated conditions.Some measures beneficial for the low friction of a crosshead slipper-guide under the rated conditions may significantly increase the friction loss of the crosshead slipper-guide system during the startup process.展开更多
Well-designed surface textures can improve the tribological properties and the efficiency of the electro-hydrostatic actuator(EHA)pump under high-speed and high-pressure conditions.This study proposes a multi-objectiv...Well-designed surface textures can improve the tribological properties and the efficiency of the electro-hydrostatic actuator(EHA)pump under high-speed and high-pressure conditions.This study proposes a multi-objective optimization model to obtain the arbitrarily surface textures design of the slipper/swash plate interface for improving the mechanical and volumetric efficiency of the EHA pump.The model is composed of the lubrication film model,the component dynamic model considering the spinning motion,and the multi-objective optimization model.In this way,the arbitrary-shaped surface texture with the best comprehensive effect in the EHA pump is achieved and its positive effects in the EHA pump prototype are verified.Experimental results show a reduction in wear and an improvement in mechanical and volumetric efficiency by 1.4%and 0.8%,respectively,with the textured swash plate compared with the untextured one.展开更多
Biti’s is one of the largest footwear manufacturers in Vietnam.Made from homegrown high-quality natural rubber,Biti’s slippers are known for their slip-resistance,durability,lightness,and breathability.In addition t...Biti’s is one of the largest footwear manufacturers in Vietnam.Made from homegrown high-quality natural rubber,Biti’s slippers are known for their slip-resistance,durability,lightness,and breathability.In addition to practicality and comfort,the products come in diverse styles at affordable prices.展开更多
基金co-supported by the National Natural Science Foundation of China (No. 51505338 and No. 51475332)the Youths Science Foundation of Zhejiang (No. LQ16E050004 and No. LQ17E050003)
文摘A thermal hydraulic model based on the lumped parameter method is presented to analyze the load-carrying capacity of a slipper pair in an aviation axial-piston pump under specified operating conditions. Both theoretical and experimental results are presented to demonstrate the validity of the thermal hydraulic model. The results illustrate that the squeezing force and thermal wedge bearing force are the main factors that affect the film thickness and load-carrying capacity.At high oil temperature and high load pressure, the film thickness decreases with increasing clamping force due to a combined action of the squeezing bearing force and the thermal wedge bearing force, but the load-carrying capacity will increase. An increase of the film thickness is proven to be beneficial under high shaft rotational speed but especially dangerous as it strongly increases the ripple amplitude of the film thickness, which leads to decreasing the load-carrying capacity. The structural parameters of the slipper can be optimized to achieve desired performance, such as the slipper radius ratio and orifice length diameter ratio. To satisfy the requirement of the load-carrying capacity, the slipper radius ratio should be selected from 1.4 to 1.8, and the orifice length diameter ratio should be selected from 4 to 5.
基金the support from the National Natural Science Foundation of China(No.51205007)the Specialized Research Fund for the Doctoral Program of Chinese Higher Education(No.20131102120019)
文摘A computational fluid dynamics （CFD） simulation method based on 3-D Navier Stokes equation and Arbitrary Lagrangian Eulerian （ALE） method is presented to analyze the grooved slip- per performance of piston pump. The moving domain of grooved slipper is transformed into a fixed reference domain by the ALE method, which makes it convenient to take the effects of rotate speed, body force, temperature, and oil viscosity into account. A geometric model to express the complex structure, which covers the orifice of piston and slipper, vented groove and the oil film, is constructed. Corresponding to different oil film thicknesses calculated in light of hydrostatic equilibrium theory and boundary conditions, a set of simulations is conducted in COMSOL to analyze the pump characteristics and effects of geometry （groove width and radius, orifice size） on these characteristics. Furthermore, the mechanics and hydraulics analyses are employed to validate the CFD model, and there is an excellent agreement between simulation and analytical results. The simulation results show that the sealing land radius, orifice size and groove width all dramatically affect the slipper behavior, and an optimum tradeoff among these factors is conducive to optimizing the pump design.
基金Supported by Open Foundation of the State Key Laboratory of Fluid Power and Mechatronic Systems(Grant No.201718).
文摘The interface between the slipper/swash plate is one of the most important frication pairs in axial piston pumps.The test of this interface in a real pump is very challenging.In this paper,a novel pump prototype is designed and a test rig is set up to study the dynamic lubricating performance of the slipper/swash-plate interface in axial piston machines.Such an experimental setup can simulate the operating condition of a real axial piston pump without changing the relative motion relationship of the interfaces.Considering the lubricant oil film thickness as the main measurement parameter,the attitude of the slipper under the conditions of different load pressure,rotation speed and charge pressure are studied experimentally.After the test,the wear state of the swash plate is observed.According to the friction trace on the surface of the swash plate,the prediction for the attitude of the slipper and the zone easy to wear are verified.
基金Project(51805376)supported by the National Natural Science Foundation of ChinaProject(LQ17E050003)supported by the Zhejiang Provincial Natural Science Foundation of China+1 种基金Project(GZKF-201719)supported by the Open Foundation of the State Key Laboratory of Fluid Power and Mechatronic Systems,ChinaProject(G20180019)supported by the Basic Scientific Research Projects Foundation of Wenzhou,China。
文摘This study investigates tribological performance of MoS2 coating on slipper pair in axial piston pump.Firstly,the MoS2 coating on the surface of slipper pair was prepared by atmospheric plasma spraying treatment technology.Secondly,the tribological characteristics of slipper pair under various working conditions were evaluated on ring-on-block tester in oil lubrication.The original and worn surfaces of the specimens were analyzed with scanning electron microscope and energy dispersive spectrometer,and then the wear morphologies of the MoS2 coatings were imaged by X-ray photoelectron spectroscopy.The experimental results showed that the friction coefficients of Cu-based materials with MoS2 coating decreased by about 0.05 at 800 N.Especially,when the external load was set to 800 N,the wear rate of the ZY331608 decreased by about 16.4%after the substrates were treated by the MoS2 coating,which exhibited excellent anti-friction and wear resistance.The formation of the MoS2 lubricating film could be classified into four stages,including the initial friction stage,anchoring stage of MoS2 on friction surface,covering stage of the sliding surface by MoS2 and the formation stage of MoS2 film.The dominating wear mechanisms of Cu-based materials with MoS2 coating were adhesive wear and abrasive wear accompanied with oxidative wear.
文摘Pressure-flow analytical formulas of lubrication film of slipper pairs on camshaft connecting rod type low speed high torque(LSHT)hydraulic motors are put forward.The bottom surface of slipper pairs is rectangle,and the effect of squeeze flow and pressure differential flow is considered.The dynamic process of lubrication film formation through squeezing is numerically studied by computer simulation.Effects of supply pressure,initial lubrication film thickness,velocity damping coefficient,loading impact and gravity,etc are studied.Advantages of novel slipper pairs with large oil cavity area are pointed out.
基金Supported by Erciyes University Scientific Research Projects Coordination Unit(Grant No.FDK-2016-6986).
文摘Oil leakage between the slipper and swash plate of an axial piston pump has a significant effect on the efficiency of the pump.Therefore,it is extremely important that any leakage can be predicted.This study investigates the leakage,oil film thickness,and pocket pressure values of a slipper with circular dimples under different working conditions.The results reveal that flat slippers suffer less leakage than those with textured surfaces.Also,a deep learning-based framework is proposed for modeling the slipper behavior.This framework is a long short-term memory-based deep neural network,which has been extremely successful in predicting time series.The model is compared with four conventional machine learning methods.In addition,statistical analyses and comparisons confirm the superiority of the proposed model.
基金Supported by the National Ministry Innovation Program of China(VTDP 3103)
文摘A novel dynamic model describing the slipper posture of the swash plate in axial piston pumps is proposed, taking into account the hydrodynamic and squeezing effects, which involves three degrees of freedom. The variation in the lubricating film thickness and the slipper tilt are accurately calculated. The influence of hydrodynamic effects and charging pressure on the slipper lubrication is discussed. The minimum film thickness, the overturning angle and the azimuth angle are obtained.Then, the trajectory of minimum thickness on the friction surface of the swash plate is predicted, the accuracy of which can be verified with the abrasion distribution of an actual swash plate. Research results can predict the durability and provide theoretical help for the design of the slipper.
基金Supported by the National Key Laboratory Foundation Project(9140C3403010903)
文摘In order to improve lubricating characteristics of slippers in an axial piston pump, the combining center cavity slipper approach was proposed based on slipper shape and moving characteristic. The cylindrical coordinate was used in the lubricant area and mesh was made. The blockweight approach was implemented to deal with non-coincidence of mesh and shallow recess border in numerical method. The finite control volume method was applied in calculating pressure distribution. The flow conservation equation and film thickness model were resolved through Gauss-Siedel relaxation iteration. The calculation and analysis results indicate that compared to the slipper （1） slip- per pressure distribution is improved; （2） hydrodynamic pressure of the combining slipper is greatly increased; （3） inclining degree is greatly reduced; （4） negative pressure in lubricant film disappear. So the combining center cavity slipper is lubricated better.
基金This work was supported by the National Key R&D Program of China(Grant No.2019YFB2004504)the National Natural Science Foundation of China(Grant No.52005323)+2 种基金the National Outstanding Youth Science Foundation of China(Grant No.51922093)the China National Postdoctoral Program for Innovative Talents(Grant No.BX20200210)the China Postdoctoral Science Foundation(Grant No.2019M660086).The。
文摘he power density of axial piston pumps can greatly benefit from increasing the speed level.However,traditional slippers in axial piston pumps are exposed to continuous sliding on the swash plate,suffering from serious wear at high rotational speeds.Therefore,this paper presents a new integrated slipper retainer mechanism for high-speed axial piston pumps,which can avoid direct contact between the slippers and the swash plate and thereby eliminate slipper wear under severe operating conditions.A lubrication model was developed for this specific slipper retainer mechanism,and experiments were carried out on a pump prototype operating at high rotational speed up to 10000 r/min.Experimental results qualitatively validated the theoretical model and confirmed the effectiveness of the new slipper design.
基金supported by the National Natural Science Foundation of China (Grant No. 51075360)the National Key Technology R&D Program of the Twelfth Five-year Plan of China (Grant No. 2011BAF09B03)the Fundamental Research Funds for the Central Universities
文摘Improving the carrying ability of oil film between slipper and swash plate and reducing the partial abrasion of slipper are important to improve the service life and reliability of axial piston pump.In this paper,a numerical simulation model was developed for slipper/swash-plate friction pair based on the elastohydrodynamic theory.The dynamic micro-motion and pressure distribution of slipper were analyzed and it was pointed out that the tilt of slipper was the main reason for its partial abrasion.The simulations about the slippers with different slopes on the outer edge of the sealing belt showed that the partial abrasion could reduce the carrying ability and increase the leakage of the slipper/swash-plate pair.The proper slope on the inner edge helped to improve the carrying ability and reduce the leakage of slipper.The experimental tests were in accord with the simulation results to a great extent,showing that the simulation model had a high accuracy and could be applied to the design and optimization of slipper,and that the slipper with optimal inner slope provided an encouraging method to improve the efficiency and reliability of axial piston pump.
基金This project was supported by the National Key Basic Research Program of China(973 Program,2014CB046404)training plan for high-level innovative talent in Guizhou province(Grant No.Q.K.H.P.T.R.C[2016]5659)+2 种基金preferred project of scientific and technological activities for personnel studying abroad in Guizhou province(Grant No.Q.R.X.M.Z.Z.H.T[2018]0001)science and technology planning project in Guizhou Province(Grant No.Q.K.H.P.T.R.C[2017]5788)key research project on Innovation group of Guizhou Provincial Education Department(Grant No.Q.J.H.KY Z.[2018]011).
文摘High-pressure axial piston pumps operate in high-speed and high-pressure environments. The contact state of the slipper against the swashplate can easily change from an oil film lubrication to a mixed oil film/asperity contact, or even dry friction. To improve the dry friction performance of slipper pairs and to avoid their potentially rapid failure, this study examined the effects of material matching on the dry friction performance of the slipper pair for high-pressure axial piston pumps. A FAIAX6 friction and wear tester was developed, and the dry friction coefficients of the slipper pairs matched with different materials were studied using this tester. Based on the thermo-mechanical coupling of the slipper pair with the working process, the contact surface temperatures of the slipper pairs matched with different materials were calculated and analyzed for the same working conditions. Following this, the effects of the material properties on the temperature increase at the slipper sliding contact surfaces were revealed. The reliabilities of the temperature calculations and analysis results were verified through orthogonal tests of slipper pairs matched with different materials. The results indicate that the influence of the material density on the friction coefficient is greater than that of the Poisson's ratio or the elastic modulus, and that the slipper material chosen should have a high thermal conductivity, low density, and low specific heat, whereas the swashplate material should be high in specific heat, density, and thermal conductivity;in addition, the slipper pair should be a type of hard material to match the type of soft material applied;that is, the hardness of the swashplate material should be greater than that of the slipper material.
基金This study was supported by the Research Project of High Technological Vessels:Development of Low Speed Marine Engines(Grant No.MC-201501-D01-03)the National Natural Science Foundation of China(Grant No.51875344).
文摘A crosshead slipper-guide system,which bears a significant thrust force,is an essential friction pair in low-speed marine diesel engines.Owing to the low moving speed of the crosshead slipper during engine startup,it is difficult to form good hydrodynamic lubrication between the crosshead slipper and guide.Therefore,a detailed analysis of the crosshead slipper during engine startup is needed.In this study,a new transient tribo-dynamic model for a crosshead slipper during the engine startup process is presented.The model consists of a mixed lubrication model of the crosshead slipper-guide and dynamic models of the piston assembly,crosshead assembly,connecting rod,and crankshaft.The tribo-dynamic performances of the crosshead slipper during startup and under the rated conditions were simulated and compared.The results show that the tribo-dynamics of the crosshead slipper during the startup process are significantly different from those under the rated conditions.Some measures beneficial for the low friction of a crosshead slipper-guide under the rated conditions may significantly increase the friction loss of the crosshead slipper-guide system during the startup process.
基金supported by the National Key R&D Program of China(Grant No.2018YFB2001101)the National Outstanding Youth Science Foundation of China(Grant No.51922093)+2 种基金the National Science Foundation for Young Scientists of China(Grant No.51905473)the Major Science and Technology Projects in Ningbo,China(Grant No.2019B10054)the Open Foundation of the State Key Laboratory of Mechanical Transmissions,China(Grant No.SKLMT-ZDKFKT-202001)。
文摘Well-designed surface textures can improve the tribological properties and the efficiency of the electro-hydrostatic actuator(EHA)pump under high-speed and high-pressure conditions.This study proposes a multi-objective optimization model to obtain the arbitrarily surface textures design of the slipper/swash plate interface for improving the mechanical and volumetric efficiency of the EHA pump.The model is composed of the lubrication film model,the component dynamic model considering the spinning motion,and the multi-objective optimization model.In this way,the arbitrary-shaped surface texture with the best comprehensive effect in the EHA pump is achieved and its positive effects in the EHA pump prototype are verified.Experimental results show a reduction in wear and an improvement in mechanical and volumetric efficiency by 1.4%and 0.8%,respectively,with the textured swash plate compared with the untextured one.
文摘Biti’s is one of the largest footwear manufacturers in Vietnam.Made from homegrown high-quality natural rubber,Biti’s slippers are known for their slip-resistance,durability,lightness,and breathability.In addition to practicality and comfort,the products come in diverse styles at affordable prices.
