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Technical Paper

Development of Nitrocarburized High Strength Crankshaft Through Controlling Vanadium Carbonitride Precipitation by Normalizing

2009-11-03
2009-32-0076
In addition to the requirements of high power output and compactness, further reduction of weight is being required for motorcycle engines from the standpoint of fuel economy and reduction of CO2 emissions. For this purpose, it is important to reduce crankshaft weight, which is the heaviest rotating part in the engine. The crankshaft has to be strong enough to bear loads, as the demands of weight reduction are increasing. Yet, productivity has to be considered at the same time even when increasing crankshaft strength. In this report of crankshaft material studies that feature high fatigue strength, machinability and distortion correct-ability, attention is given to the fact that the amount of vanadium, which is known as an element that enhances the strength with its precipitation, accelerates deposition, dissolved in the steel depends on the heating temperature.
Technical Paper

Research on Dynamic Behavior Simulation Technology for Cam-Drive Mechanism in Single-cylinder Engines

2009-11-03
2009-32-0089
A theoretical evaluation technology for timing chain systems in single-cylinder engine has been established. Hitherto, there have been almost no theoretical evaluation reports published about drive loss and slapping noise in cam drive systems including timing chains. Thus, tensioner lifter and tensioner guide specifications to satisfy requirements related to slapping noise and friction loss have been determined only by tests with actual engines. In this research, a highly accurate mechanism-simulation model has been constructed that takes into account factors such as dynamic characteristics along with crank sprocket and timing chain contact stiffness and friction coefficient in addition to static characteristics of the timing chain and tensioner guide. Our results have confirmed a high correlation with actual engine tests at an absolute value level.
Technical Paper

Development of Technologies for Improving Fuel Economy of Small Motorcycle Engines

2009-11-03
2009-32-0083
A single cylinder gasoline engine of displacement 125 cm3 for prototype was developed, and the fuel economy of this engine was improved by reducing friction and improving combustion. For reducing friction, various methods were innovated; enhancement of the oil film retention by modifying the striation finish on piston skirt, adding the needle bearing to the rocker arm shaft, press-fitting the bush into the small end of connecting rod, reducing contact pressure with the piston ring, and spray coating molybdenum disulfide onto the shift fork. By innovating these friction reduction methods, the friction of the engine was reduced by 6% compared to the previous model which was already employed the roller rocker arm and the offset cylinder. For improving combustion, the swirl control valve (SCV) was installed into the intake port. By the effect of SCV, both improvement of engine power and improving combustion under low load was achieved.
Technical Paper

Research on Measurement and Simulation Technology of Valve Behavior during Engine Firing

2011-04-12
2011-01-0743
A measurement method for valve behavior during engine firing is established. In order to grasp valve behavior accurately, it has been required to develop a measurement method for valve behavior that takes in account for the condition during engine firing. However, behaviors of a valve train have generally been analyzed during engine motoring because it is difficult to measure them during engine firing. In this study, valve behavior during engine firing can be measured accurately by attaching a gap sensor to the valve guide. Furthermore, the simulation system for valve behavior that treated the valve train as three-dimensional flexible body is built. Under engine motoring condition, high correlation between measurement and simulation is confirmed for valve behavior and spring stress.
Technical Paper

Influence of a Fast Injection Rate Common Rail Injector for the Spray and Combustion Characteristics of Diesel Engine

2011-04-12
2011-01-0687
For reduction of NOx and soot emission with conventional diesel diffusion combustion, the authors focused on enhancement of the rate of injection (hereafter referred to as RoI) to improve air availability, thus enhancing the fuel distribution and atomization. In order to increase opening ramp of the RoI (hereafter referred to as fast injection rate), a hydraulic circuit was improved and nozzle geometries were optimized to make the greatest use of the advantages of the hydraulic circuit. Two different common rail injectors were prepared for this research. One is a mass production-type injector with piezo actuator that achieved the EURO-V exhaust gas emission standards, and the other is a prototype injector equipped with the new hydraulic circuit. The nozzle needle of the prototype injector is directly actuated by high-pressure fuel from common rail to improve the RoI.
Technical Paper

New Proposal of Piston Skirt Form using Multi Objective Optimization Method

2011-04-12
2011-01-1079
A multi-objective optimization model using a piston behavior simulation for the prediction of NV, friction and scuffing was created. This model was used to optimize the piston skirt form, helping to enable well-balanced forms to be sought. Optimization calculations, involving extended analyses and numerous design variables, conventionally necessitate long calculation times in order to achieve adequate outcomes. Because of this, in the present project data was converted into functions in order to help enable the complex piston skirt form to be expressed using a small amount of coefficients. Using the limit values for manufacturability and the degree of contribution to the target functions, the scope of design variables was restricted, and the time necessary for the analysis was significantly reduced. This has helped to enable optimal solutions to be determined within a practical time frame.
Technical Paper

Prediction Method of Surface Pressure against Gasket in Consideration of Creep on Cylinder Head in Air-Cooled Engines

2012-10-23
2012-32-0104
A method was designed to predict the gasket surface pressure in consideration of creep which occurs on the surface of the gasket side of the cylinder head in air-cooled engines. Creep caused by heat can cause major deformation on the gasket side of the cylinder head in air-cooled engines, which may result in combustion gas leaking from between the cylinder and cylinder head. Until now, there have been no reports of methods to accurately predict phenomena relating to this deformation in the initial stage of engine design. This study combined values of strain and temperature occurring on the gasket side of the cylinder head, obtained through FEM analysis of steady heat transfer and thermal stress, with unit test results showing the domains in which the influence of the creep is critical or not. This information was used to design a method to determine whether or not an engine's specifications fell into a domain in which creep would have an effect, and predict surface pressure.
Journal Article

Investigation of Combustion Diagnosis System Applied for the Development of General Purpose Utility Engines

2012-10-23
2012-32-0100
The chief goal of engineers studying internal combustion engines is to improve energy efficiency in the face of the increasingly severe global warming and energy issues. Hence, there have been numerous studies focusing on the combustion reactions in order to develop clean and reliable combustion that is capable of operating using less fuel. And to improve the comprehension of engine performance and its combustion reactions, development of comprehensive measurement technique for engine performance, in-cylinder visualization technique, and numerical simulations, is essential and strongly demanded. There have hitherto been numerous studies about combustion diagnostics and analysis, including high-efficiency measurement techniques using response surface method the air-fuel mixture distribution and flame propagation measurement with optical visualization techniques, and numerical calculations of combustion reaction with elementary reactions.
Journal Article

Development of New V6 3.5L Gasoline Engine for ACURA RLX

2013-04-08
2013-01-1728
Honda has developed a new next-generation 3.5 L V6 gasoline engine using our latest Earth Dreams Technology. The overall design objective for the engine was to reduce CO₂ emissions and provide driving exhilaration. The Earth Dreams Technology concept is to increase fuel economy while reducing emissions. To achieve this and provide an exhilarating driving experience, 3-stage Variable Valve Timing and Lift Electronic Control (VTEC) was combined with the Variable Cylinder Management (VCM) system. This valve train technology in conjunction with Direct Injection (DI), resulted in dramatic improvements in output (a 3.3% increase) and combined mode fuel economy (20% reduction). Helping to achieve Midsize Luxury Sedan level NV, a new mount system was developed to reduce engine vibrations during three-cylinder-mode operation. In this paper, we will explain the 3-stage VTEC with VCM + DI system, friction reducing technology, and the structure and benefit of the new engine mount system.
Technical Paper

Development of Aluminum Powder Metal Composite Material Suitable for Extrusion Process used for Cylinder Sleeves of Internal Combustion Engines

2014-04-01
2014-01-1002
There are a couple of ways to manufacture aluminum cylinder blocks that have a good balance between productivity and abrasion resistance. One of them is the insert-molding of a sleeve made of PMC (Powder Metal Composite) by the HPDC (High Pressure Die Casting) method. However, in this method, cracks are apt to occur on the surface when the PMC sleeve is extruded and that has been a restriction factor against higher extrusion speed. The authors attempted to raise this extrusion temperature by eliminating the Cu additive process from the aluminum alloy powder in order to raise its melting point by approximately 50 °C. This enabled the wall of the extruded sleeve to be thinner and the extrusion speed to be higher compared to those of a conventional production method while avoiding the occurrence of surface cracks.
Technical Paper

Precise Fuel Control of Diesel Common-Rail System by Using OFEM

2010-04-12
2010-01-0876
Multiple injections that are necessary to reduce emissions, noise, and vibration of diesel engine have been accomplished by common-rail fuel injection system. Especially a fuel amount of each injection has to be tightly controlled, but actually there is a difference between an actual amount and a target one. Injection period will be determined according to a map in that the relation between injected amount and injection period is stated. But in the case of multiple injections, pressure wave caused by previous injections remain in a common-rail system at the time an injection second or later starts. Therefore, actual amounts injected will be different from target ones. In order to compensate the difference, the method that the influence of pressure wave on fuel amount injected is also investigated and injection period will be corrected is realized in an actual engine control system. Meanwhile, pressure wave propagation in common-rail has been studied.
Technical Paper

Development of Evaluation Method for Low-Cycle Fatigue Breakdown on HSDI Diesel Cylinder Head

2010-04-12
2010-01-0695
With a growing demand for high-power diesel engines, a key issue in engine development is to create efficient methods for developing highly durable cylinder heads, without having to repeat trial-and-error testing. Especially, it was difficult to accurately predict the occurrence and origin of cracks on the surfaces of cylinder heads in hot and cold cycle engine operation. This paper describes a thermal fatigue evaluation method developed by analyzing areas around the glow plug hole where cracks often occur during hot and cold cycle engine operation. To reveal the conditions of edges from which cracks were formed under engine durability tests, we used two procedures. One was estimating local temperature of edge areas based on material hardness determination, in order to compensate for the accuracy of the thermal analysis. The other was analyzing the strain amplitudes on the cylinder head surface using computer simulation.
Journal Article

In-cylinder Optical Investigation of Combustion Behavior on a Fast Injection Rate Diesel Common Rail Injector

2011-08-30
2011-01-1821
The field of diesel combustion research is producing numerous reports on studies of premixed combustion, which promises simultaneous reduction of both NOx and soot, in order to meet increasingly stringent regulations on harmful emissions from automobiles. However, although premixed combustion can simultaneously reduce both NOx and soot, certain issues have been pointed out, including the fact that it emits greater quantities of unburned HC and CO gases and the fact that it limits the operating range. Furthermore, this combustion method sets the ignition delay longer with the aim of promoting the mixing of fuel and air. This raises issues with the product due to the combustion instability and sensitivity to the uneven fuel properties that are found on the market, the capability of the engine response under transient conditions, the deterioration in combustion noise, and so on.
Technical Paper

Effects of Hydrogen Addition to Intake Mixture on Cyclic Variation of Diesel Engine

2011-08-30
2011-01-1964
The present study experimentally investigated cyclic variation of combustion characteristics of a diesel engine with hydrogen added to the intake air in detail. As the result, there were three ignition modes: (1) hydrogen ignition mode, (2) hydrogen-assisted ignition mode, and (3) diesel-fuel ignition mode. Ignition timing fluctuated from cycle to cycle in each ignition mode and between one ignition mode and another mode. As the coolant temperature was increased, the number of cycles in diesel-fuel ignition mode decreased, and indicated thermal efficiency and cyclic variation was improved. In the case with the blow-by gas introduced to intake port, preflame reaction of blow-by gas first occurred, ignited hydrogen, and then diesel-fuel was ignited by hydrogen combustion in hydrogen ignition mode and hydrogen-assisted ignition mode.
Technical Paper

Estimation of Indicated Mean Effective Pressure Using Crankshaft Angular Velocity Variation

2011-11-08
2011-32-0510
We have successfully developed a system to estimate Indicated Mean Effective Pressure (hereafter "IMEP") by detecting the crankshaft angular velocity variation during one cycle of a four-stroke single-cylinder gasoline engine. The system has been commercially applied to the spark-ignition timing control system for small-displacement motorcycle engines. The determined amplitude of crankshaft angular velocity variation during one cycle is defined as "delta omega (Δω)." The relationship between Δω and IMEP has been experimentally examined using engine unit bench tests and actual motorcycles. From the experimental results, it was confirmed that Δω represents IMEP. This paper discusses the experimental study on the estimation of IMEP using crankshaft angular velocity variation.
Technical Paper

Research on Noise Reduction of Linkage Drive Gear in Extended Expansion Linkage Engine

2011-11-08
2011-32-0538
The authors have reported on a study on extended expansion linkage engine to enhance thermal efficiency since 2006. This report discusses the use of a test engine applied to a Micro Combined Heat and Power Generation Unit for household use, in order to reduce engine noise at a rated operation. Test engine noise is mainly caused by gear meshing for the multiple linkage system, so helical gear with higher contact ratio than that of spur gear was used. Measurement of engine noise revealed that test engine noise increased by 3.2 dB(A) over compared conventional engine. From results of behavior analysis by mechanical simulation, when transmission direction of the relative torque between the crankshaft and the eccentric shaft is reversed, the direction of the thrust force acting on the gear is reversed. For this reason, the test engine noise increases because each shaft vibrates, and rattle noise occurs.
Technical Paper

Numerical Analysis of Turbocharger Response Delay Mechanism

2010-04-12
2010-01-1226
Increasing fuel economy is highly demanded because of the GHG reduction today. Turbocharged downsized engines have much attention as one of the effective technology for this demand. Turbocharged boost technology enables to increase thermal efficiency, but this also has a response delay known as turbo lag, which may cause lower engine performance and poor drivability. This issue impedes the broader application of this technology. The research discussed in this paper focused on turbo lag, and adopted a numerical approach to analyzing the detailed mechanism of this phenomenon. The study concluded that turbo lag is a delay in the boost pressure response that originates from a combination of factors. The primary factor in turbo lag is a delay that is due to physical properties of the turbocharger system; the secondary factor is a decreased effective turbine energy caused by a shift in the operating point, resulting from the primary factor.
Technical Paper

Introduction of a New Method of Solving Wear Problems Caused by the Swing Motion Occurring between the Roller and the Sliding Contact Surface

2010-04-12
2010-01-1055
In an attempt to decrease the amount of CO2 emitted by engines and yet improve engine output power, various approaches to the development of variable valve-lift mechanisms and the application of direct fuel injection and supercharger mechanisms are rapidly gaining popularity. In the case of the swing motion which takes place in variable valve-lift mechanisms, the relative speed between the two components reaches zero at the location where the load is high and the oil film tends to break, thereby leading to wear. Furthermore, the use of a supercharger and a direct injection device generates soot, which promotes further wear. Therefore establishing a reliable method for estimating wear has become a pressing issue. Wear problems caused by the swing motion occur during boundary lubrication, and we have devised a solution for them.
Technical Paper

Technologies for Practical Application of a TBW System for Large Motorcycle with Improved Driving Feel, Sound Quality, and Layout Flexibility

2010-04-12
2010-01-1094
Honda R&D has developed a throttle-by-wire (TBW) system that meets the needs of motorcycles where the attitude of the vehicle body is controlled by operation of the throttle. To gain high response and following for the throttle valve, we employed a new adaptive control algorithm. The newly developed system has an idling combustion stabilization function and a three-dimensional control function for the throttle-opening map based on running gear and engine speed. With those functions, we improved the controllability of the motorcycle, especially for small throttle openings. Furthermore, we improved the feeling of the limiter control used in maximum-speed limitation. For the overall system, intake system related devices are consolidated to improve the layout flexibility and expand the mounting options on the motorcycle.
Technical Paper

A Study of High Power Output Diesel Engine with Low Peak Cylinder Pressure

2010-04-12
2010-01-1107
This study examined a high-speed, high-powered diesel engine featuring a pent-roof combustion chamber and straight ports, with the objective of improving the specific power of the engine while minimizing any increase in the maximum cylinder pressure (Pmax). The market and contemporary society expect improvements in the driving performance of diesel-powered automobiles, and increased specific power so that engine displacement can be reduced, which will lessen CO2 emissions. When specific power is increased through conventional methods accompanied with a considerable increase in Pmax, the engine weight is increased and friction worsens. Therefore, the authors examined new technologies that would allow to minimize any increase in Pmax by raising the rated speed from the 4000 rpm of the baseline engine to 5000 rpm, while maintaining the BMEP of the baseline engine.
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