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Technical Paper

Mechanism of Improving Fuel Efficiency by Miller Cycle and Its Future Prospect

1995-02-01
950974
We have introduced a supercharged Miller Cycle gasoline engine into the market in 1993 as an answer to the requirement of reduction in CO2 emission of vehicles. Improvement in the fuel economy of a supercharged Miller Cycle engine is achieved by the reduction of friction loss due to a smaller displacement. The biggest problem of a conventional supercharged engine is knocking. In order to avoid the knocking, lower compression ratio, which accompanies lower expansion ratio, has been adopted by the conventonal engines and achieved insufficient fuel economy improvement. The Miller Cycle obtains superior anti-knocking performance as well as lowering compression ratio, while keeping the high expansion ratio. The decreased friction loss by the smaller displacement has completely lead to the improvement of fuel economy.
Technical Paper

Improving NOx and Fuel Economy for Mixture Injected SI Engine with EGR

1995-02-01
950684
A large quantity of recirculated exhaust gas is used to reduce NOx emissions and improve fuel economy at the same time. The effect of exhaust gas recirculation (EGR) was investigated under the stoichiometric and lean operating conditions and compared with the effect of lean operation without EGR. A mixture injected SI engine that has a mechanically driven mixture injection valve installed was prepared. In this engine, it is possible to charge combustible mixture independently from combustion air and recirculated exhaust gas introduced from intake port in order to stratify the mixture. The effect of the EGR ratio on NOx emissions and fuel consumption was measured under the stoichiometric and lean operating conditions. Due to the mixture distribution controlled by the mixture injection, a large quantity of recirculated exhaust gas could be introduced into the combustion chamber under the stoichiometric air/fuel ratio. The limit of EGR ratio was 48 %.
Technical Paper

Development of Lean Burn Catalyst

1995-02-01
950746
A new type of three way catalyst for lean engine was developed in order to reduce hydrocarbon (HC), carbon-monoxide (CO) and nitrogen-oxides (NOx) in lean exhaust gas. This catalyst has a base support material of MFI zeolite loaded with active metals including platinum (Pt), iridium (Ir) and rhodium (Rh). It showed good catalytic activity and thermal durability on a lean engine. This catalyst made it possible to enlarge the lean operating region of the lean burn engine. It showed the NOx reduction of 51% in Japanese 10-15 mode emission test and the emissions were found low enough to satisfy the new Japanese emission standards. Consequently, fuel economy of the lean vehicle with this catalyst has been improved about 16% in comparison with a comparable current stoichiometric combustion vehicle. This catalyst has been mass-produced for Mazda 323 lean burn vehicle (Z-Lean) for the Japanese domestic market.
Technical Paper

The Characteristics of Fuel Consumption and Exhaust Emissions of the Side Exhaust Port Rotary Engine

1995-02-01
950454
Mazda has been pursuing the research of side exhaust porting for its rotary engine in an effort to improve the engine's fuel efficiency and exhaust emissions characteristics. The side exhaust porting configuration provides greater flexibility in setting port timing and shape, as compared to the peripheral exhaust porting configuration, which is in use in the current-generation rotary engines; the side exhaust porting configuration enables the selection of a port timing more favorable to reduced fuel consumption and exhaust emissions. The side exhaust port rotary engine used in this research has its exhaust port closure timing around the top dead center (TDC) and has no intake-exhaust timing overlap. As a result, burnt gasses entering the next cycle of combustion are reduced, thus enhancing combustion stability; also, the air-fuel ratio can be set leaner for improved fuel consumption.
Technical Paper

The Effect of Operating Conditions at Idle in the S.I. Engine

1997-10-01
972990
A gasoline engine with an electronically controlled fuel injection system has substantially better fuel economy and lower emissions than a carburetted engine. In general, the stability of engine operation is improved with fuel injector, but the stability of engine operation at idle is not improved compared with a carburetted gasoline engine. In addition, the increase in time that an engine is at idle due to traffic congestion has an effect on the engine stability and vehicle reliability. Therefore, in this research, we will study the influence of fuel injection timing, spark timing, dwell angle, and air-fuel ratio on engine stability at idle.
Technical Paper

Making the Case for a Next Generation Automotive Electrical System

1998-10-19
98C006
Introduction of an array of new electrical and electronic features into future vehicles is generating vehicle electrical power requirements that exceed the capabilities of today's 14 volt electrical systems. In the near term (5 to 10 years), the existing 14V system will be marginally capable of supporting the expected additional loads with escalating costs for the associated charging system. However, significant increases in vehicle functional content are expected as future requirements to meet longer-term (beyond 10 years) needs in the areas of emission control, fuel economy, safety, and passenger comfort. A higher voltage electrical system will be required to meet these future requirements. This paper explores the functional needs that will mandate a higher voltage system and the benefits derivable from its implementation.
Technical Paper

A Study of Exhaust and Noise Emissions Reduction on a Single Spray Direct Injection

1989-02-01
890467
Exhaust and noise emissions were successfully reduced using a Single Spray Direct Injection Diesel Engine (SSDI) on a two-liter naturally-aspirated four-cylinder engine. The compression ratio, the swirl ratio and the pumping rate were optimized to obtain good fuel economy, high power output and low exhaust emissions. Furthermore, through a modification of the fuel injection equipment, hydrocarbon (HC) emissions were reduced. Upon a test vehicle evaluation of this engine, more than 11% fuel savings relative to Mazda two-liter Indirect Injection Diesel Engines (IDI) were obtained. As for engine noise, structural modifications of the engine were carried out to obtain noise emission levels equivalent to IDI.
Technical Paper

Complete Ceramic Swirl Chamber for Passenger Car Diesel Engine

1987-02-01
870650
The U.S. Federal Emission Standards ruled that particulate emissions from '87 models should be no more than 0.20 g/mile for passenger cars and 0.26 g/mile for light-duty trucks. A complete ceramic swirl chamber with a heat insulating air gap has been developed to meet the above standards without sacrificing fuel economy or power output. The whole process by which the ceramic swirl chamber was developed will be described: optimization of materials, design, manufacturing, and the method and system of quality control. The results of long term durability tests will be described, which demonstrate the chamber's excellent reliability.
Technical Paper

Mazda New Lightweight and Compact V6 Engines

1992-02-01
920677
Mazda has developed new-generation V6 engines. The new V6 series comprises 2.5-litre, 2.0-litre and 1.8-litre engines. The development objective was to ensure high output performance for excellent “acceleration and top-end feel”, while satisfying “Clean & Economy” requirements. The engines also had to have a pleasant sound. Mazda selected for these engines a short stroke, 60° V-shaped 24 valve DOHC with an aluminum cylinder block. Various techniques are adopted as follows: Combustion improvement and optimization of control to achieve high fuel economy and low emissions Improvement of volumetric efficiency, inertia reduction of rotating parts and optimization of control to achieve excellent “acceleration and top-end feel” Adoption of a high-rigidity, two-piece cylinder block and crankshaft and weight reduction of reciprocating parts to achieve a pleasant engine sound Material changes and elimination of dead space to achieve a compact, lightweight engine
Technical Paper

Surrounding Combustion Process (SCP) - New Concept for Lean Burn Engine

1992-02-01
920058
Both NOx and unburned HC were reduced by changing the direction of the flame propagation. It is generally said that the optimum ignition position of spark ignition engine is in the center of combustion chamber. However by igniting arround the chamber and propagating the flame toward the center, a smooth heat release pattern due to the decrease in the flame area and a decrease in the unburned gas entering the ring crevise can be anticipated. These effects of this combustion process, which was named the surrounding combustion process (SCP), were experimntally confirmed using the constant volume combustion vessels and the spark ignition engine equipped with six spark plugs per cylinder. Next, the steps for decreasing the number of ignitions TCre considered, and additional three spark plugs for SCP were installed in the four valve pentroof combustion chamber. With this engine, the NOx reduction and the capability of SCP to further improve the lean burn engine fuel economy were confirmed.
Technical Paper

Mazda 4-Rotor Rotary Engine for the Le Mans 24-Hour Endurance Race

1992-02-01
920309
The “R26B” 4-rotor rotary engine is a powerplant that brought a Mazda racing car to victory in the 1991 Le Mans 24-hour endurance race. This engine was developed to achieve high levels of power output, fuel efficiency, and reliability, as required of endurance racing engines. This paper describes the basic structure of the engine, including a 3-piece eccentric shaft that represents a major technological achievement incorporated in the engine, as well as other technological innovations employed for the enhancement of the engine's power output and reliability, and for reducing its fuel consumption. These innovations include a telescopic intake manifold system, peripheral port injection, 3-plug ignition system, 2-piece ceramic apex seal, and a cermet coating on the rubbed surfaces of the housings.
Technical Paper

Real World Performance of an Onboard Gasoline/Ethanol Separation System to Enable Knock Suppression Using an Octane-On-Demand Fuel System

2018-04-03
2018-01-0879
Higher compression ratio and turbocharging, with engine downsizing can enable significant gains in fuel economy but require engine operating conditions that cause engine knock under high load. Engine knock can be avoided by supplying higher-octane fuel under such high load conditions. This study builds on previous MIT papers investigating Octane-On-Demand (OOD) to enable a higher efficiency, higher-boost higher compression-ratio engine. The high-octane fuel for OOD can be obtained through On-Board-Separation (OBS) of alcohol blended gasoline. Fuel from the primary fuel tank filled with commercially available gasoline that contains 10% by volume ethanol (E10) is separated by an organic membrane pervaporation process that produces a 30 to 90% ethanol fuel blend for use when high octane is needed. In addition to previous work, this paper combines modeling of the OBS system with passenger car and medium-duty truck fuel consumption and octane requirements for various driving cycles.
Technical Paper

LOOP SCAVENGING versus THROUGH SCAVENGING of TWO-STROKE ENGINES

1958-01-01
580044
THIS paper reports the latest investigation of the relative merits of loop scavenging versus through scavenging. The authors hope that the conditions of the work permitted an objective evaluation of the two types of engines. The results of the study may be summarized as follows: 1. With symmetrical timing, neither cylinder shows significant advantage in trapping efficiency. 2. With symmetrical timing, the best ratio of exhaust-port to inlet-port effective area seems to be about 0.6. 3. Unsymmetrical timing is an effective method of improving trapping efficiency. 4. The value of net indicated fuel economy shows no significant difference between the two cylinders. The authors point out that because the areas were equal it is unlikely that the optimum port design of each type was used in comparing the cylinders. If optimum porting had been used, the two types might have shown more difference.
Technical Paper

New Methodology of Life Cycle Assessment for Clean Energy Vehicle and New Car Model

2011-04-12
2011-01-0851
Mazda announced that all customers who purchase Mazda cars are provided with the joy of driving and excellent environmental and safety performance under slogan of "Sustainable Zoom-Zoom" long-term vision for technology development. The purpose of this study is to develop a new approach of Life Cycle Assessment (abbreviated to LCA) to be applied to clean energy vehicles and new car models. The improvement of both environmental performance, e.g., fuel consumption, exhaust emissions, vehicle weight reduction, and LCA that is a useful methodology to assess the environmental load of automobiles for their lifecycles has become more important. LCA by inventory analysis, for RX-8 Hydrogen RE as a rotary engine vehicle used hydrogen as clean energy, was carried out and disclosed the world for the first time. LCA for new Mazda 5 was carried out as the portfolio of all models, previously only the specific model equipped with fuel efficiency device based on ISO14040.
Technical Paper

A General Method of Life Cycle Assessment

2012-04-16
2012-01-0649
In previous Life Cycle Assessment (LCA) methods, environmental burden items to be analyzed, prior to a life cycle inventory analysis, were assumed as the main factors of environmental problems regardless of the product category. Next, the life cycle inventory analysis, in which the total amount of environmental burden items emitted during the life cycle of a product was calculated, and an environmental impact assessment were performed. The environmental impact assessment was based on the initially assumed environmental burden items. The process, in other words, was a particular solution based on this assumption. A general solution unconstrained by this assumption was necessary. The purpose of this study was to develop a general method of LCA that did not require such initially assumed environmental burden items, and to make it possible to perform a comprehensive environmental impact assessment and strategically reduce environmental burden of a product.
Technical Paper

Optimizing Base Oil Viscosity Temperature Dependence For Power Cylinder Friction Reduction

2014-04-01
2014-01-1658
Lubricant viscosity along the engine cylinder liner varies by an order of magnitude due to local temperature variation and vaporization effects. Tremendous potential exists for fuel economy improvement by optimizing local viscosity variations for specific operating conditions. Methods for analytical estimation of friction and wear in the power-cylinder system are reviewed and used to quantify opportunities for improving mechanical efficiency and fuel economy through lubricant formulation tailored specifically to liner temperature distributions. Temperature dependent variations in kinematic viscosity, density, shear thinning, and lubricant composition are investigated. Models incorporating the modified Reynolds equation were used to estimate friction and wear under the top ring and piston skirt of a typical 11.0 liter diesel engine.
Technical Paper

Investigating the Effect of Intake Manifold Size on the Transient Response of Single Cylinder Turbocharged Engines

2017-09-04
2017-24-0170
This paper evaluates the lag time in a turbocharged single cylinder engine in order to determine its viability in transient applications. The overall goal of this research is to increase the power output, reduce the fuel economy, and improve emissions of single cylinder engines through turbocharging. Due to the timing mismatch between the exhaust stroke, when the turbocharger is powered, and the intake stroke, when the engine intakes air, turbocharging is not conventionally used in commercial single cylinder engines. Our previous work has shown that it is possible to turbocharge a four stroke, single cylinder, internal combustion engine using an air capacitor, a large volume intake manifold in between the turbocharger compressor and engine intake. The air capacitor stores compressed air from the turbocharger during the exhaust stroke and delivers it during the intake stroke.
Technical Paper

Modeling Costs and Fuel Economy Benefits of Lightweighting Vehicle Closure Panels

2008-04-14
2008-01-0370
This paper illustrates a methodology in which complete material-manufacturing process cases for closure panels, reinforcements, and assembly are modeled and compared in order to identify the preferred option for a lightweight closure design. First, process-based cost models are used to predict the cost of lightweighting the closure set of a sample midsized sports utility vehicle (SUV) via material and process substitution. Weight savings are then analyzed using a powertrain simulation to understand the impact of lightweighting on fuel economy. The results are evaluated in the context of production volume and total mass change.
Technical Paper

Development of a Technique to Strengthen Body Frame with Structural Foam

2001-03-05
2001-01-0313
A technique to strengthen body frame with a polymeric structural foam has been developed with benefits of reducing vehicle weight and improving drivability and fuel economy. The idea of this new technology was evolved from the concept that body frame strength will increase drastically if the body frames are prevented from folding on collision. The energy of a collision impact would be effectively absorbed if weak portions of body frames are reinforced by a high strength structural foam. The new technology composed of the high strength structural foam and a light-weight frame structure with partial foam filling is reported here.
Technical Paper

Application of Plasma Welding to Tailor- Welded Blanks

2003-10-27
2003-01-2860
In recent years, improving fuel efficiency and collision safety are important issue. We have worked on a new construction method to develop body structure which is light weight and strong/stiff. We adopt multi type Tailor-Welded Blanks (TWB) which is formed after welding several steel sheets for ATENZA (MAZDA 6), NEW DEMIO (MAZDA 2), and RX-8. This is a technology to consistently improve of such product properties and to reduce costs. Laser welding is a common TWB welding method, but for further equipment cost reductions and productivity improvements, we have developed a higher welding speed and robust plasma welding and introduced this to mass production. We introduce this activity and results in this report.
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