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Technical Paper

Water Jacket Spacer for Improvement of Cylinder Bore Temperature Distribution

2005-04-11
2005-01-1156
For reduction of fuel consumption, a new device “Water Jacket Spacer” which improves temperature distribution of a cylinder block bore wall was developed. In the case of a conventional cylinder block, coolant flow concentrates at the bottom and middle region of the water jacket. While temperature of the upper bore wall is high (due to high-temperature combustion gas) the temperature of the lower bore wall is low, since its only function is to support the piston. When the developed spacer is inserted into a water jacket, the coolant flow concentrates at the upper part of the jacket. As a result, cooling ability to the upper bore wall was improved and temperature of lower bore wall was increased, thereby reducing fuel consumption.
Technical Paper

Two-Dimensional Temperature Measurements in Diesel Piston Bowl Using Phosphor Thermometry

2009-09-13
2009-24-0033
Phosphor thermometry was used during fuel injection in an optical engine with the glass piston of reentrant type. SiO2 coated phosphor particle was used for the gas-phase temperature measurements, which gave much less background signal. The measurements were performed in motored mode, in combustion mode with injection of n-heptane and in non-combustion mode with injection of iso-octane. In the beginning of injection period, the mean temperature of each injection cases was lower than that of the motored case, and temperature of iso-octane injection cases was even lower than that of n-heptane injection cases. This indicates, even if vaporization effect seemed to be the same at both injection cases, the effect of temperature decrease changed due to the chemical reaction effect for the n-heptane cases. Chemical reaction seems to be initiated outside of the fuel liquid spray and the position was moving towards the fuel rich area as the time proceeds.
Journal Article

Toyota's Integrated Drive Power Control System for Downsized Turbocharged Engine

2015-04-14
2015-01-1636
New engine controls have been developed for the turbocharged Lexus NX200t to improve driving power by reducing engine torque output lag. Drive power management functions have been centralized in an integrated drive power control system. The newly developed controls minimize the potential reduction in drivability associated with the adoption of a turbocharged engine while improving fuel efficiency. General driveability issues commonly associated with a turbocharged engine include sudden increases in drive power due to the response lag of the turbocharger, and higher shifting frequencies if this response lag triggers a disturbed accelerator operation pattern by the driver. The developed technologies detect and control sudden increases in drive power to create the optimum drive power map, and reduce unnecessary shifts even if the driver's accelerator operation is disturbed.
Technical Paper

Toyota Newly Developed 2VZ-FE Type Engine

1988-11-01
881775
Newly developed 2VZ-FE engine for CAMRY is a 2.5-liter water cooled and V-type 6-cylinder engine exported from TOYOTA for the first time. This engine has the TOYOTA original 4-valve DOHC system. That is, exhaust camshafts driven by intake camshafts using scissors gears. By its compact configuration with the gear driven camshafts, this V-type 6-cylinder engine is mounted on a front-wheel-drive vehicle which originally had an in-line 4-cylinder engine. By increasing IVZ-FE engine displacement (for domestic), compact pentroof-type combustion chambers, optimum air-fuel ratio and ignition timing by TCCS (TOYOTA Computer Controlled System) and other technologies, a high performance 153HP/5600rpm and a large torque 155ft·lbs/4400rpm have been achieved with a low fuel consumption.
Technical Paper

Theoretical Study on Spray Design for Small-Bore Diesel Engine

2016-04-05
2016-01-0740
1 Recently, demand for small-bore compact vehicle engines has been increasing from the standpoint of further reducing CO2 emissions. The generalization and formulation of combustion processes, including those related to emissions formation, based on a certain similarity of physical phenomena regardless of engine size, would be extremely beneficial for the unification of development processes for various sizes of engines. The objective of this study is to clarify what constraints are necessary for engine/nozzle specifications and injection conditions to achieve the same combustion characteristics (such as heat release rate and emissions) in diesel engines with different bore sizes.
Technical Paper

The New Toyota Inline 4 Cylinder 1.8L ESTEC 2ZR-FXE Gasoline Engine for Hybrid Car

2016-04-05
2016-01-0684
The engine in the new fourth generation Prius carries over the same basic structure as the 2ZR-FXE used in the third generation and incorporates various refinements to enhance fuel efficiency. Called the ESTEC 2ZR-FXE, the new engine incorporates various fuel efficient technologies to improve combustion characteristics, knocking, and heat management, while also reducing friction. As a result of this meticulous approach to enhancing fuel efficiency, the new engine is the first gasoline engine in the world to achieve a maximum thermal efficiency of 40%. This paper describes the fuel efficient technologies incorporated into this engine.
Technical Paper

The Effect of Gasoline Metallic Additives on Low Speed Pre-Ignition

2018-04-03
2018-01-0936
Methylcyclopentadienyl manganese tricarbonyl (MMT) is used as an octane-enhancing metallic additive for unleaded gasoline which can prevent engine knock by proactive reaction with the hydrocarbon free radicals before starting the auto-ignition of hydrocarbons. However it has been pointed out that MMT causes automotive catalysts clogging and spark plug severely fouling. Therefore, many countries have fuel standards that prohibit or limit the usage of MMT. Nevertheless, some countries still use MMT as there are no restrictions imposed by fuel standards. As mentioned in several papers, metallic additives of engine oil such as calcium cause an abnormal combustion phenomenon called low-speed pre-ignition (LSPI) in turbocharged spark ignition engines. In contrast, the effect of metallic additives of gasoline such as MMT on LSPI has not been studied.
Technical Paper

Study of a Two-Degree-of-Freedom Exhaust System

1990-02-01
900164
An investigation was conducted into pressure pulsation in the exhaust port, which greatly affects volumetric efficiency and engine performance. From experiments using a single blow-down generator, it was established that the amplitude of the pressure pulsation increases as the manifold branch is lengthened and that large negative pressure synchronized with the timing of valve overlap can be obtained if a proper branch length is used. The performance of a 2ℓ test engine was optimized by varying the length of both the manifold branches and front pipe forks. It was found that whereas front pipe fork length affects engine performance over only a narrow range of engine speed, optimizing manifold branch length results in a considerable improvement over a wide engine speed range. In the course of optimizing the exhaust pipe manifold length of this two-degree-of-freedom exhaust system, abnormal exhaust noises were emitted at specific engine speeds during deceleration.
Technical Paper

Study of Mileage-Related Formaldehyde Emission from Methanol Fueled Vehicles

1990-02-01
900705
In order to determine the main factors causing the mileage-related increase in formaldehyde emission from methanol-fueled vehicles, mileage was accumulated on three types of vehicle, each of which had a different air-fuel calibration system. From exhaust emission data obtained during and after the mileage accumulation, it was found that lean burn operation resulted in by far the highest formaldehyde emission increase. An investigation into the reason for the rise in engine-out formaldehyde emission revealed that deposits in the combustion chamber emanating from the lubricating oil promotes formaldehyde formation. Furthermore it was learnt that an increase in engine-out NOx emissions promotes partial oxidation of unburned methanol in the catalyst, leading to a significant increase in catalyst-out formaldehyde emission.
Technical Paper

Small Bore Diesel Engine Combustion Concept

2015-04-14
2015-01-0788
Small bore diesel engines often adopt a two-valve cylinder head and a non-central injector layout to expand the port flow passage area. This non-central injector layout causes asymmetrical gas flow and fuel distribution, resulting in worse heat losses and a less homogenous fuel-air mixture than an equivalent four-valve cylinder head layout with a central injector. This paper describes the improvement of piston bowl geometry to achieve a more homogeneous gas flow and fuel-air mixture. This concept reduced fuel consumption by 2.5% compared to the original piston bowl geometry, while also reducing NOx emissions by 10%.
Technical Paper

Research on the Measures for Improving Cycle-to-Cycle Variations under High Tumble Combustion

2016-04-05
2016-01-0694
Improving vehicle fuel economy is a central part of efforts toward achieving a sustainable society. An effective way for accomplishing this aim is to enhance the engine thermal efficiency. Measures to mitigate knocking and reduce engine cooling heat loss are important aspects of enhancing the engine thermal efficiency. Cooled exhaust gas recirculation (EGR) is regarded as a key technology because it is capable of achieving both of these objectives. For this reason, it has been adopted in a wide range of both hybrid and conventional vehicles in recent years. Toyota has been introducing these technologies as ESTEC (Economy with Superior Thermal Efficient Combustion). Improving cycle-to-cycle variations in combustion, in addition to fast combustion is essential for achieving high engine thermal efficiency.
Technical Paper

Research of Knocking Deterioration due to Accumulated Carbon Deposits on Piston Surfaces

2019-04-02
2019-01-1141
In recent years, fuel economy regulation is expanding to reduce CO2 emission and energy saving in world wide. To achieve the regulation, automaker efforts to develop electrification technology and improve engine thermal efficiency with high compression ratio. On the other hand, variety of fuels such as a reformed gasoline and bio fuel share is growing rapidly to utilize of fossil fuel by legal arrangements. With the spread of reformed gasoline, there are some risk of increased carbon deposit and accumulated on piston surface, due to heavy aromatic and olefin in the fuel. In combustion point of view, knocking should be deteriorated by synergy effect both accumulated carbon deposit and said high compression ratio. Furthermore, knocking deterioration do not occur in regularly, especially they occur in low-middle engine load. However, this mechanism is not clear.
Journal Article

Reduction of Heat Loss and Improvement of Thermal Efficiency by Application of “Temperature Swing” Insulation to Direct-Injection Diesel Engines

2016-04-05
2016-01-0661
The reduction of the heat loss from the in-cylinder gas to the combustion chamber wall is one of the key technologies for improving the thermal efficiency of internal combustion engines. This paper describes an experimental verification of the “temperature swing” insulation concept, whereby the surface temperature of the combustion chamber wall follows that of the transient gas. First, we focus on the development of “temperature swing” insulation materials and structures with the thermo-physical properties of low thermal conductivity and low volumetric heat capacity. Heat flux measurements for the developed insulation coating show that a new insulation material formed from silica-reinforced porous anodized aluminum (SiRPA) offers both heat-rejecting properties and reliability in an internal combustion engine. Furthermore, a laser-induced phosphorescence technique was used to verify the temporal changes in the surface temperature of the developed insulation coating.
Technical Paper

Reduction of Friction Losses in Crankcase at High Engine Speeds

2006-10-16
2006-01-3350
Recently, engines achieving high power levels are becoming increasingly common. The trend is toward increasing the inflow of lubricating oil into the crankcase through several factors (for example, increasing the flow rate of the cooling oil jets in order to reduce the thermal load of the pistons). In addition, the mechanical losses induced by the motion of the crankshaft and connecting rods through the additional oil are intensified due to the higher engine speeds at maximum power. In this article, we confirmed a method of separating the pumping loss and the agitation loss by measuring the pressure in the crankcase and an empirical formula was found for predicting pumping loss from displacement and ventilating area. We also investigated the effect of reducing the lubrication oil flow rate, as well as other factors affecting the oil flow, on the mechanical loss at high engine speeds.
Technical Paper

Reducing the Amount of Lubricating Engine Oil by Using a New Crankshaft Bearing with Eccentric Oil Groove

2004-10-25
2004-01-3048
Oil pump down sizing is one of the effective method to improve engine friction loss. Reducing the required amount of lubricating engine oil can be achieved by the application of a new crankshaft bearing with an eccentric oil groove. By adopting a bearing with an eccentric groove, we found the well balanced specification which can keep the necessary amount of oil to the crankshaft pin and reduce leaking oil from crankshaft main journal. Measuring oil amount distribution in engine running condition simultaneously and checking capability of eliminating contamination analytically have achieved.
Technical Paper

Performance of Two/Four Stroke Gasoline HCCI Engine with Electromagnetic Valve Train

2007-07-23
2007-01-1868
Comparison of net thermal efficiency and emission in two and four stroke gasoline HCCI engine has been carried out for various valve-timings as negative valve overlap and exhaust valve double opening. The valve timings could easily be converted from a mode to another by configuring schedule of electromagnetic valve-train. Extension of operable torque with high thermal efficiency had been expected in two-stroke HCCI operation, however friction and supercharger loss curtailed about half of the gain in indicated thermal efficiency. In four-stroke operation modes, exhaust valve double opening (‘reinduction’ or ‘rebreathing’) showed the best net thermal efficiency and emission, however the extension of high load limit could not be achieved considerably.
Technical Paper

Numerical Analysis of Flow in the Induction System of an Internal Combustion Engine -Multi-Dimensional Calculation Using a New Method of Lines

1990-02-01
900255
Multi-dimensional code has been developed to simulate the effect of geometry on mass flow rate and flow pattern in the induction system of an internal combustion engine. The unsteady compressible Navier-Stokes equations in general curvilinear coordinates are solved by a new method of lines. In the method of lines, the governing equations are spatially discretized by a finite difference approximation and the resulting system of ordinary differential equations is integrated. As a time integration scheme, we newly propose to use the rational Runge-Kutta scheme in order to efficiently simulate the flows in the induction system. The domain-decomposition technique is introduced so that body-fitted structured grid can be easily generated for such complex geometry as a real intake port shape. The present code is applied to 2 and 3 dimensional steady flows in intake port/cylinder assembly with a valve.
Technical Paper

Novel Power Conversion System for Cost Reduction in Vehicles with 42V/14V Power Supply

2003-03-03
2003-01-0307
In recent years, attention is being given to 42V power supply technology for solving the problem of increased power demand in vehicles. Since 2001, Toyota Motor Corporation has been marketing a mild hybrid system (THS-M) in order to further improve fuel economy and reduce emissions; this system requires both 42V and 14V power sources. The THS-M system consists of a 42V motor generator (M/G) connected to the engine crankshaft with a belt; an inverter; a 36V battery; a DC/DC converter for stepping down the 42V power supply to a conventional 12V battery; and high-power related electrical components. These components require additional costs, which must be reduced in order to increase the sales volume of THS-M vehicles. We have devised a method to eliminate the conventional DC/DC converter from the THS-M, and as a result we have developed a new, revolutionary power conversion system (multi-function inverter).
Technical Paper

Multipoint Spark Ignition for Lean Combustion

1985-10-01
852092
Effects of multipoint spark ignition on combustion duration, fuel consumption and lean misfire limit are discussed in this paper. A plate, which consists of 12 spark gaps in each cylinder, and a new CD ignition system have been developed for accomplishing the multipoint spark ignition. This plate was installed between cylinder block and head in a 4 cylinder engine. Compared with a single gap, the results of 12 gaps showed a reduced combustion duration by about 50%, a 5% decrease in fuel consumption and an extended lean misfire limit by about 3 air-fuel ratio numbers. Furthermore, the multipoint spark ignition on both sides of the combustion chamber was more effective than only on one side. With this system, HC emission can be reduced as well. The results of this study showed that, compared to those obtained with swirl, this multipoint spark ignition was more effective on improving fuel consumption.
Technical Paper

Mechanism of Turbocharger Coking in Gasoline Engines

2015-09-01
2015-01-2029
Turbocharged downsized gasoline engines have been widely used in the market as one of the measures to improve fuel economy. Coking phenomena in the lubricating circuit of the turbocharger unit is a well-known issue that may affect turbocharger efficiency and durability. Laboratory rig test such as ASTM D6335 (TEOST 33C) has been used to predict this phenomenon as a part of engine oil performance requirements. On the other hand, laboratory tests sometimes have difficulty reproducing the actual mechanism of coking caused by engine oil degradation. Accumulation of insoluble material is one of the important gasoline engine oil degradation modes. The influence of temperature and insoluble concentration were investigated based on actual used engine oils collected in the field.
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