The performance and particulate emission of a diesel engine are affected by the consumption of lubricating oil. Most studies on oil consumption mechanism of the cylinder have been done by using the experimental method...The performance and particulate emission of a diesel engine are affected by the consumption of lubricating oil. Most studies on oil consumption mechanism of the cylinder have been done by using the experimental method, however they are very costly. Therefore, it is very necessary to study oil consumption mechanism of the cylinder and obtain the accurate results by the calculation method. Firstly, four main modes of lubricating oil consumption in cylinder are analyzed and then the oil consumption rate under common working conditions are calculated for the four modes based on an engine. Then, the factors that affect the lubricating oil consumption such as working conditions, the second ring closed gap, the elastic force of the piston rings are also investigated for the four modes. The calculation results show that most of the lubricating oil is consumed by evaporation on the liner surface. Besides, there are three other findings： （1） The oil evaporation from the liner is determined by the working condition of an engine; （2） The increase of the ring closed gap reduces the oil blow through the top ring end gap but increases blow-by; （3） With the increase of the elastic force of the ring, both the left oil film thickness and the oil throw-off at the top ring decrease. The oil scraping of the piston top edge is consequently reduced while the friction loss between the rings and the liner increases. A neural network prediction model of the lubricating oil consumption in cylinder is established based on the BP neural network theory, and then the model is trained and validated. The main piston rings parameters which affect the oil consumption are optimized by using the BP neural network prediction model and the prediction accuracy of this BP neural network is within 8%, which is acceptable for normal engineering applications. The oil consumption is also measured experimentally. The relative errors of the calculated and experimental values are less than 10%, verifying the validity of the simulation results. Applying the established simulation model and the validated BP network model is able to generate numerical results with sufficient accuracy, which significantly reduces experimental work and provides guidance for the optimal design of the piston rings diesel engines.展开更多
In order to prolong the service life of piston rings of heavy vehicle engine and decrease the friction and wear of piston rings and cylinder liner,CrMoN/MoS_2 multilayer films were deposited on the surface of rings by...In order to prolong the service life of piston rings of heavy vehicle engine and decrease the friction and wear of piston rings and cylinder liner,CrMoN/MoS_2 multilayer films were deposited on the surface of rings by magnetron sputtering and low temperature ion sulfuration.FESEM equipped with EDX was adopted to analyze the compositions and morphologies of surface,cross-section,and wear scars of the multilayer films.The nano-hardness and Young＇s modulus of the films were measured by a nano tester.Tribologicalproperties of the films were tested by an SRV~174;4 wear tester.The experimentalresults indicate that the structures of the multilayer films are dense and compact.The films possess nano hardness value of approximately 26.7 GPa and superior ability of plastic deformation resistance.The multilayer films can activate solid lubricating,and possess an excellent antifriction and wear resistance under the conditions of heavy load,high frequency,high temperature,and dynamic load.展开更多
The friction and wear properties,as well as the scuffing resistance,of different piston-ring coatings mating with a chrome-plated cylinder liner were investigated.Interrupted wear tests under the lubricant starvation ...The friction and wear properties,as well as the scuffing resistance,of different piston-ring coatings mating with a chrome-plated cylinder liner were investigated.Interrupted wear tests under the lubricant starvation condition were conducted to examine the wear behavior of Cr-diamond coating(GDC)and diamond-like coating(DLC).The results indicated that the DLC coating had outstanding tribological properties(small coefficient of friction and wear loss)at 150°C,while the GDC coating exhibited better performance at an elevated temperature(240°C).The DLC coating had a better scuffing resistance;no material adhesion occurred for 70 min under the unlubricated condition.The interrupted wear behaviors revealed that the scuffing process of the GDC coating involved the consumption of lubricant oil with relatively stable wear,a reduction in the friction force,and the occurrence of scuffing,in sequence.In contrast,although the friction force also increased after a short period of weak friction,no scuffing was observed.This is attributed to the formation of a mixed oxide and graphitic C tribolayer.展开更多
It is of a vital importance to reduce the frictional losses in marine diesel engines. Advanced surface textures have provided an e ective solution to friction performance of rubbing pairs due to the rapid development ...It is of a vital importance to reduce the frictional losses in marine diesel engines. Advanced surface textures have provided an e ective solution to friction performance of rubbing pairs due to the rapid development of surface engineering techniques. However,the mechanisms through which textured patterns and texturing methods prove beneficial remains unclear. To address this issue,the tribological system of the cylinder liner?piston ring(CLPR) is investigated in this work. Two types of surface textures(Micro concave,Micro V?groove) are processed on the cylinder specimen using di erent processing methods. Comparative study on the friction coe cients,worn surface texture features and oil film characteristics are performed. The results demonstrate that the processing method of surface texture a ect the performance of the CLPR pairs under the specific testing conditions. In addition the micro V?groove processed by CNCPM is more favorable for improving the wear performances at the low load,while the micro?con?cave processed by CE is more favorable for improving the wear performances at the high load. These findings are in helping to understand the e ect of surface texture on wear performance of CLPR.展开更多
As a hydrogen-rich carbon-free fuel,ammonia fuel has recently attracted considerable attention in the engine field.However,few studies on the tribological properties of ammonia-fueled engines have been reported,which ...As a hydrogen-rich carbon-free fuel,ammonia fuel has recently attracted considerable attention in the engine field.However,few studies on the tribological properties of ammonia-fueled engines have been reported,which limits the development of ammonia-fueled engines.In this study,the tribological behaviors of the cylinder liner‒piston ring(CLPR)were studied under dry friction,water,and ammonia solution media.The results indicated that both the water medium and the ammonia solution medium have a certain lubricating effect.The main wear mechanism of CLPR in dry friction is abrasive wear.In both the water medium and the ammonia solution medium,the surface damage to the CLPR was dominated by tribocorrosion,but their action mechanisms were completely different.The presence of ammonia causes the microelectrolytic reaction of the CLPR and changes the tribological behavior of the CLPR.展开更多
The effects of ultra-dispersed diamond (UDD) on the friction force, wear, and temperature of tri-bological pairs have been investigated. The experimental tests were carried out on a modified piston ring-cylinder liner...The effects of ultra-dispersed diamond (UDD) on the friction force, wear, and temperature of tri-bological pairs have been investigated. The experimental tests were carried out on a modified piston ring-cylinder liner bench tester with different particle mass fractions of 0, 0.02%, and 0.10%. The results show that compared with a pure fluid, the mixture of the fluid and UDD not only reduces the friction and wear, but also reduces the bulk temperature of the specimen. The mechanism by which the UDD lubricant improves the tribological properties has some relationship with surface topography, because it can increase the bearing capability of surfaces.展开更多
The radial surface coating layer of compression piston rings is used to improve their wear resistance during the internal combustion engine operation.However,at top dead centers,the friction coefficient of the piston ...The radial surface coating layer of compression piston rings is used to improve their wear resistance during the internal combustion engine operation.However,at top dead centers,the friction coefficient of the piston ring–cylinder liner pair is detrimental to the engine’s tribological performance.In this work,dimples with different texture dimensions and densities were tested in a home-developed tribometer.The friction coefficient was measured for all samples,and for those with the best results,their wear resistance was assessed.The texture with an aspect ratio of 0.25 and a density area of 15%reported the best tribological results.展开更多
To reduce the friction of a piston ring while maintaining a large oil film load-carrying capacity,an approach comprising of the inverse method and the sequential quadratic programming algorithm was proposed.The approa...To reduce the friction of a piston ring while maintaining a large oil film load-carrying capacity,an approach comprising of the inverse method and the sequential quadratic programming algorithm was proposed.The approach considers the variation of mixed lubrication and variable lubricant viscosity with temperature along the engine stroke,is developed to optimize the profile of a piston ring.A piston ring profile is represented by a polynomial function.A case study of the second piston ring shows that the proposed method can be applied for the optimization of a piston ring profile.In addition,this paper illustrates the effects of the degree of a polynomial function.The results show that the minimization of friction and maximization of oil film load-carrying capacity can be balanced simultaneously when the degree of the polynomial is 2 and 5.展开更多
This study involves the application of carbon nanotubes (CNTs) to a piston ring and cylinder liner system in order to investigate their effect on friction and wear under dry and lubricated conditions.Carbon nanotubes ...This study involves the application of carbon nanotubes (CNTs) to a piston ring and cylinder liner system in order to investigate their effect on friction and wear under dry and lubricated conditions.Carbon nanotubes were used as a solid lubricant and lubricant additive in dry and lubricated conditions,respectively.Simulation and measurement of friction and wear were conducted using a reciprocating tribometer.Surface analysis was performed using a scanning electron microscope and an energy dispersive spectrometer.The results indicate that carbon nanotubes can considerably improve the tribological performance of a piston ring and cylinder liner system under dry sliding conditions,whereas improvement under lubricated conditions is not obvious.Under dry friction,the effective time of the CNTs is limited and the friction coefficient decreases with an increase in CNT content.Furthermore,the dominant wear mechanism during dry friction is adhesive.展开更多
To reduce the fuel consumption of internal combustion engines, more attention has been paid to the tribological performance of the piston ring pack during the cold start and idle operations. In this research, a numeri...To reduce the fuel consumption of internal combustion engines, more attention has been paid to the tribological performance of the piston ring pack during the cold start and idle operations. In this research, a numerical model considering the cylinder liner deformation and the piston ring conformability is developed to predict the blow-by, lubrication, friction and wear of the piston ring pack under different operating conditions. The gas flow rate, inter-ring gas pressures, minimum oil film thickness, frictional force and wear load during cold start are calculated and compared with those during warm idle operating conditions. The results show that cylinder liner deformation and piston ring conformability together obviously affect blow-by and other tribological performance. Meanwhile, it is found that friction loss is larger during cold start than during warm idle operating conditions. However, the wear process is more severe during warm idle operation than during cold start. From this research, the blow-by and tribological performance of the piston ring pack during cold start and warm idle operations are understood more deeply.展开更多
Ⅰ. Current Situation At present, there are more than 100 piston and/or piston ring manufacturers all over China, and the figure is continuously rising. Among them, some manufacturers are specialized or mainly engaged...Ⅰ. Current Situation At present, there are more than 100 piston and/or piston ring manufacturers all over China, and the figure is continuously rising. Among them, some manufacturers are specialized or mainly engaged in the production of pistons, e. g. Shanghai Piston Plant, Shandong Piston Plant, etc.; some manufacturers are specialized or展开更多
For the ring/liner conjunction, well‐designed surface texturing has been regarded as a potential means to improve its tribological performance, as well as the application of coating. However, so far most researchers ...For the ring/liner conjunction, well‐designed surface texturing has been regarded as a potential means to improve its tribological performance, as well as the application of coating. However, so far most researchers focused on the one of these aspects. In this study, the combined effect of coating and texturing on the performance of ring/liner conjunction is numerically investigated. A thermal mixed lubrication model is presented. The effects of the coating's thermal and mechanical properties on the tribological performance are studied under the cold and warm engine operating conditions. Along with the increasing coating thickness, the effects of the coating's thermal properties on friction loss are found to be significant, as well as the effects of the coating's mechanical properties. It is also found that a soft coating with a lower thermal inertia has a greater ability to reduce the friction loss of the textured conjunction.展开更多
基金supported by National Natural Science Foundation of China (Grant No. 50975192)Specialized Research Foundation for the Doctoral Program of Higher Education of China (Grant No.20090032110001)
文摘The performance and particulate emission of a diesel engine are affected by the consumption of lubricating oil. Most studies on oil consumption mechanism of the cylinder have been done by using the experimental method, however they are very costly. Therefore, it is very necessary to study oil consumption mechanism of the cylinder and obtain the accurate results by the calculation method. Firstly, four main modes of lubricating oil consumption in cylinder are analyzed and then the oil consumption rate under common working conditions are calculated for the four modes based on an engine. Then, the factors that affect the lubricating oil consumption such as working conditions, the second ring closed gap, the elastic force of the piston rings are also investigated for the four modes. The calculation results show that most of the lubricating oil is consumed by evaporation on the liner surface. Besides, there are three other findings： （1） The oil evaporation from the liner is determined by the working condition of an engine; （2） The increase of the ring closed gap reduces the oil blow through the top ring end gap but increases blow-by; （3） With the increase of the elastic force of the ring, both the left oil film thickness and the oil throw-off at the top ring decrease. The oil scraping of the piston top edge is consequently reduced while the friction loss between the rings and the liner increases. A neural network prediction model of the lubricating oil consumption in cylinder is established based on the BP neural network theory, and then the model is trained and validated. The main piston rings parameters which affect the oil consumption are optimized by using the BP neural network prediction model and the prediction accuracy of this BP neural network is within 8%, which is acceptable for normal engineering applications. The oil consumption is also measured experimentally. The relative errors of the calculated and experimental values are less than 10%, verifying the validity of the simulation results. Applying the established simulation model and the validated BP network model is able to generate numerical results with sufficient accuracy, which significantly reduces experimental work and provides guidance for the optimal design of the piston rings diesel engines.
基金Funded by the National Natural Science Foundation of China(No.50901089)the Project supported by Army Important Researches(No.2012ZB02)
文摘In order to prolong the service life of piston rings of heavy vehicle engine and decrease the friction and wear of piston rings and cylinder liner,CrMoN/MoS_2 multilayer films were deposited on the surface of rings by magnetron sputtering and low temperature ion sulfuration.FESEM equipped with EDX was adopted to analyze the compositions and morphologies of surface,cross-section,and wear scars of the multilayer films.The nano-hardness and Young＇s modulus of the films were measured by a nano tester.Tribologicalproperties of the films were tested by an SRV~174;4 wear tester.The experimentalresults indicate that the structures of the multilayer films are dense and compact.The films possess nano hardness value of approximately 26.7 GPa and superior ability of plastic deformation resistance.The multilayer films can activate solid lubricating,and possess an excellent antifriction and wear resistance under the conditions of heavy load,high frequency,high temperature,and dynamic load.
基金This research was supported by the Natural Science Foundation of Liaoning Province(2019-ZD-0165 and 2020-HYLH-47)the China Postdoctoral Science Foundation(2020M670729)the National Natural Science Foundation of China(51979018).
文摘The friction and wear properties,as well as the scuffing resistance,of different piston-ring coatings mating with a chrome-plated cylinder liner were investigated.Interrupted wear tests under the lubricant starvation condition were conducted to examine the wear behavior of Cr-diamond coating(GDC)and diamond-like coating(DLC).The results indicated that the DLC coating had outstanding tribological properties(small coefficient of friction and wear loss)at 150°C,while the GDC coating exhibited better performance at an elevated temperature(240°C).The DLC coating had a better scuffing resistance;no material adhesion occurred for 70 min under the unlubricated condition.The interrupted wear behaviors revealed that the scuffing process of the GDC coating involved the consumption of lubricant oil with relatively stable wear,a reduction in the friction force,and the occurrence of scuffing,in sequence.In contrast,although the friction force also increased after a short period of weak friction,no scuffing was observed.This is attributed to the formation of a mixed oxide and graphitic C tribolayer.
基金Supported by National Natural Science Foundation of China(Grant No.51422507)Hubei Provincial Natural Science Foundation of China(Grant No.2015CFB372)+1 种基金Fundamental Research Funds for the Central Universities of China(Grant No.2015IVA010)Tribology Science Fund of State Key Laboratory of Tribology of China(Grant No.SKLTKF14B03)
文摘It is of a vital importance to reduce the frictional losses in marine diesel engines. Advanced surface textures have provided an e ective solution to friction performance of rubbing pairs due to the rapid development of surface engineering techniques. However,the mechanisms through which textured patterns and texturing methods prove beneficial remains unclear. To address this issue,the tribological system of the cylinder liner?piston ring(CLPR) is investigated in this work. Two types of surface textures(Micro concave,Micro V?groove) are processed on the cylinder specimen using di erent processing methods. Comparative study on the friction coe cients,worn surface texture features and oil film characteristics are performed. The results demonstrate that the processing method of surface texture a ect the performance of the CLPR pairs under the specific testing conditions. In addition the micro V?groove processed by CNCPM is more favorable for improving the wear performances at the low load,while the micro?con?cave processed by CE is more favorable for improving the wear performances at the high load. These findings are in helping to understand the e ect of surface texture on wear performance of CLPR.
基金supported by the Study on Tribology and Lubrication Technology of the Marine Low-Speed Engine(No.CBG5N21-1-2)the Tribological Design and Experimental Verification of Key Moving Parts(No.DE0305)+1 种基金the Study on the Key Technologies of Green Ammonia Synthesis and Engine Applicationthe Fundamental Research Funds for the Central Universities.
文摘As a hydrogen-rich carbon-free fuel,ammonia fuel has recently attracted considerable attention in the engine field.However,few studies on the tribological properties of ammonia-fueled engines have been reported,which limits the development of ammonia-fueled engines.In this study,the tribological behaviors of the cylinder liner‒piston ring(CLPR)were studied under dry friction,water,and ammonia solution media.The results indicated that both the water medium and the ammonia solution medium have a certain lubricating effect.The main wear mechanism of CLPR in dry friction is abrasive wear.In both the water medium and the ammonia solution medium,the surface damage to the CLPR was dominated by tribocorrosion,but their action mechanisms were completely different.The presence of ammonia causes the microelectrolytic reaction of the CLPR and changes the tribological behavior of the CLPR.
基金Supported by the National Natural Science Foundation of China (No. 50275046)
文摘The effects of ultra-dispersed diamond (UDD) on the friction force, wear, and temperature of tri-bological pairs have been investigated. The experimental tests were carried out on a modified piston ring-cylinder liner bench tester with different particle mass fractions of 0, 0.02%, and 0.10%. The results show that compared with a pure fluid, the mixture of the fluid and UDD not only reduces the friction and wear, but also reduces the bulk temperature of the specimen. The mechanism by which the UDD lubricant improves the tribological properties has some relationship with surface topography, because it can increase the bearing capability of surfaces.
基金supported by Fundação para a Ciência e Tecnologia(FCT)and MAHLE,Componentes de Motores,S.A.through the grant SFRH/BDE/110654/2015by the project Add-Additive with the reference POCI-01-0247-FEDER-024533.
文摘The radial surface coating layer of compression piston rings is used to improve their wear resistance during the internal combustion engine operation.However,at top dead centers,the friction coefficient of the piston ring–cylinder liner pair is detrimental to the engine’s tribological performance.In this work,dimples with different texture dimensions and densities were tested in a home-developed tribometer.The friction coefficient was measured for all samples,and for those with the best results,their wear resistance was assessed.The texture with an aspect ratio of 0.25 and a density area of 15%reported the best tribological results.
基金This study is supported by the National Natural Science Foundation of China，Research Project of State Key Laboratory of Mechanical System and Vibration
文摘To reduce the friction of a piston ring while maintaining a large oil film load-carrying capacity,an approach comprising of the inverse method and the sequential quadratic programming algorithm was proposed.The approach considers the variation of mixed lubrication and variable lubricant viscosity with temperature along the engine stroke,is developed to optimize the profile of a piston ring.A piston ring profile is represented by a polynomial function.A case study of the second piston ring shows that the proposed method can be applied for the optimization of a piston ring profile.In addition,this paper illustrates the effects of the degree of a polynomial function.The results show that the minimization of friction and maximization of oil film load-carrying capacity can be balanced simultaneously when the degree of the polynomial is 2 and 5.
基金The research presented in this paper was partially funded by the National Natural Science Foundation of China，Research Project of State Key Laboratory of Mechanical System and Vibration
文摘This study involves the application of carbon nanotubes (CNTs) to a piston ring and cylinder liner system in order to investigate their effect on friction and wear under dry and lubricated conditions.Carbon nanotubes were used as a solid lubricant and lubricant additive in dry and lubricated conditions,respectively.Simulation and measurement of friction and wear were conducted using a reciprocating tribometer.Surface analysis was performed using a scanning electron microscope and an energy dispersive spectrometer.The results indicate that carbon nanotubes can considerably improve the tribological performance of a piston ring and cylinder liner system under dry sliding conditions,whereas improvement under lubricated conditions is not obvious.Under dry friction,the effective time of the CNTs is limited and the friction coefficient decreases with an increase in CNT content.Furthermore,the dominant wear mechanism during dry friction is adhesive.
基金supported by the National Natural Science Foundation of China(Grant No.51375300)the Research Project of State Key Laboratory of Mechanical System and Vibration(Grant No.MSVZD201401)
文摘To reduce the fuel consumption of internal combustion engines, more attention has been paid to the tribological performance of the piston ring pack during the cold start and idle operations. In this research, a numerical model considering the cylinder liner deformation and the piston ring conformability is developed to predict the blow-by, lubrication, friction and wear of the piston ring pack under different operating conditions. The gas flow rate, inter-ring gas pressures, minimum oil film thickness, frictional force and wear load during cold start are calculated and compared with those during warm idle operating conditions. The results show that cylinder liner deformation and piston ring conformability together obviously affect blow-by and other tribological performance. Meanwhile, it is found that friction loss is larger during cold start than during warm idle operating conditions. However, the wear process is more severe during warm idle operation than during cold start. From this research, the blow-by and tribological performance of the piston ring pack during cold start and warm idle operations are understood more deeply.
文摘Ⅰ. Current Situation At present, there are more than 100 piston and/or piston ring manufacturers all over China, and the figure is continuously rising. Among them, some manufacturers are specialized or mainly engaged in the production of pistons, e. g. Shanghai Piston Plant, Shandong Piston Plant, etc.; some manufacturers are specialized or
基金supported by the National Natural Science Foundation of China (Nos. 51375300 and 51575342)the Research Project of State Key Laboratory of Mechanical System and Vibration (No. MSVZD201701) for supporting this research
文摘For the ring/liner conjunction, well‐designed surface texturing has been regarded as a potential means to improve its tribological performance, as well as the application of coating. However, so far most researchers focused on the one of these aspects. In this study, the combined effect of coating and texturing on the performance of ring/liner conjunction is numerically investigated. A thermal mixed lubrication model is presented. The effects of the coating's thermal and mechanical properties on the tribological performance are studied under the cold and warm engine operating conditions. Along with the increasing coating thickness, the effects of the coating's thermal properties on friction loss are found to be significant, as well as the effects of the coating's mechanical properties. It is also found that a soft coating with a lower thermal inertia has a greater ability to reduce the friction loss of the textured conjunction.
