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Technical Paper

Development of High-resolution Exciting Source Identification System

We have developed an excitation source identification system that can distinguish excitation sources on a sub-assembly level (around 30mm) for vehicle components by combining a measurement and a timing analysis. Therefore, noise and vibration problems can be solved at an early stage of development and the development period can be shortened. This system is composed of measurement, control, modeling, and excitation source identification parts. The measurement and the excitation source identification parts are the main topics of this paper. In the measurement part, multiple physical quantities can be measured in multi-channel (noise and vibration: 48ch, general purpose: 64ch), and these time data can be analyzed by using a high-resolution signal analysis (Instantaneous Frequency Analysis (IFA)) that we developed.
Technical Paper

Development of Predictive Powertrain State Switching Control for Eco-Saving ACC

In recent years, improvement of in-use fuel economy is required with tightening of exhaust emission regulation. We assume that one of the most effective solutions is ACC (Adaptive Cruise Control), which can control a powertrain accurately more than a driver. We have been developing a fuel saving ADAS (Advanced Driver Assistance System) application named “Sailing-ACC”. Sailing-ACC system uses sailing stop technology which stops engine fuel injection, and disengages a clutch coupling a transmission when a vehicle does not need acceleration torque. This system has a potential to greatly improve fuel efficiency. In this paper, we present a predictive powertrain state switching algorithm using external information (route information, preceding vehicle information). This algorithm calculates appropriate switching timing between a sailing stop mode and an acceleration mode to generate a “pulse-and-glide” pattern.
Journal Article

Multi-Fidelity Total Integrated Simulation Technology for High Pressure Pump with Squeeze Film Effect

Automotive fuel can be efficiently combusted by injecting it into the cylinders at high pressure to atomize it to pass the regulations for exhaust gas and fuel economy. For this reason, automotive companies have developed direct injection engines, which can inject gasoline into the cylinders directly. Furthermore, the demand for lower-noise high pressure pumps is also increasing from the viewpoint of automotive comfort. Since the valve velocity and noise level will increase as the pressure in fuel pumps increases, noise problems need to be solved under the high pressure conditions. Accordingly, the valve motion should be predicted with high accuracy under operating conditions to evaluate the noise caused by valve impingement. In addition, the squeeze film effect phenomenon will occur in the physical fuel pumps affect the prediction of the noise level caused by valve impingement.
Technical Paper

Development of Breath-Alcohol-Detection System

The problem of high fatal accident rates due to drunk driving persists, and must be reduced. This paper reports on a prototype system mounted on a car mock-up and a prototype portable system that enables the checking of the drivers’ sobriety using a breath-alcohol sensor. The sensor unit consists of a water-vapor-sensor and three semiconductor gas sensors for ethanol, acetaldehyde, and hydrogen. One of the systems’ features is that they can detect water vapor from human-exhaled breath to prevent false detection with fake gases. Each gas concentration was calculated by applying an algorithm based on a differential evolution method. To quickly detect the water vapor in exhaled breath, we applied an AC voltage between the two electrodes of the breath-water-vapor sensor and used our alcohol-detection algorithm. The ethanol level was automatically calculated from the three gas sensors as soon as the water vapor was detected.
Journal Article

Development of a New Metal Substrate for Lean NOx Trap

This paper presents a new substrate for Lean NOx Traps (LNT) which enables high NOx conversion efficiency, even after long-term aging, when using alkali metals as the NOx adsorber. When a conventional metal honeycomb is used as the LNT substrate, the chromium in the metal substrate migrates into the washcoat and reacts with the alkali metals after thermal aging. In order to help prevent this migration, we have developed a new substrate where a fine -alumina barrier is precipitated to the surface of the metal substrate. The new substrate is highly capable of preventing migration of chromium into the washcoat and greatly enhances the NOx conversion. The durability of the new substrate and emission test using a test vehicle are also examined.
Technical Paper

A Virtual ECU and Its Application to Control System Analysis - Power Window System Demonstration

A virtual power window control system was built in order to look into and demonstrate applications of microcontroller models. A virtual ECU simulated microcontroller hardware operations. The microcontroller program, which was written in binary digital codes, was executed step-by-step as the virtual ECU simulation went on. Thus, production-ready codes of ECUs are of primary interest in this research. The mechanical system of the power window, the DC motor to lift the window glass, the H-bridge MOSFET drivers, and the current sensing circuit to detect window locking are also modeled. This means that the hardware system of the control system was precisely modeled in terms of mechanical and circuit components. By integrating these models into continuous and discrete co-simulation, the power window control system was analyzed in detail from the microscopic command execution of the microcontroller to the macroscopic motion of the window mechanism altogether.
Technical Paper

A Safety Concept based on a Safety Sustainer for Highly Automated Driving Systems

Highly automated driving systems have a responsibility to keep a vehicle safe even in abnormal conditions such as random or systematic failures. However, creating redundancy in a system to respond to failures increases the cost of the system, and simple redundancy cannot detect systematic failures because some systematic failures occur in each system at the same time. Systematic failures in automated driving systems cannot be verified sufficiently during the development phase due to numerous patterns of parameters input from outside the system. A safety concept based on a “safety sustainer” for highly automated driving systems is proposed. The safety sustainer is designed for keeping a vehicle in a safe state for several seconds if a failure occurs in the system and notifying the driver that the system is in failure mode and requesting the driver to take over control of the vehicle.
Technical Paper

Dissolution of the Gap between Safety Requirements Written in a Natural Language and Formal Notations

Safety concepts are essential to conform to functional safety standard ISO 26262 for automotive products. Safety requirements, which are a part of safety concepts, shall be satisfied by products to avoid hazards by vehicles to maintain their safety. Incompleteness of safety requirements must be avoided in deriving parent requirements to its children. However, measure for checking is only reviewing when the safety requirements are described in a natural language. This measure for checking is not objective or stringent. We developed a specification technique written in formal notation that addresses some of the shortcomings of capturing safety requirements for verification purposes. Safety requirements in this notation are expressed in goal tree models, which originate from goal-oriented requirement engineering Knowledge Acquisition in autOmated Specification (KAOS). Each requirement is written with propositional logic as the node of a tree.
Technical Paper

Development of a Highly Accurate Air-Fuel Ratio Control Method Based on Internal State Estimation

A fuel injection control method is developed in which the transient air-fuel ratio is accurately controlled by an internal state estimation method with dynamic characteristics. With conventional methods the air-fuel ratio control precision is limited, because the air measurement system, the air and the fuel dynamic characteristics lack precision. In this development, the factors disturbing the air-fuel ratio under transient conditions are determined by analysis of the control mechanisms. The disturbance factors are found to be (1) the hot wire sensor has a delay time, (2) manifold air charging causes an overshoot phenomenon, (3) there is a dead time between sensing and fuel flow into the cylinder and (4) there is a delay of fuel flow into the cylinder caused by the fuel film. Compensation schemes are constructed for each of these technical problems.
Technical Paper

An Automatic Parameter Matching for Engine Fuel Injection Control

An automatic matching method for engine control parameters is described which can aid efficient development of new engine control systems. In a spark-ignition engine, fuel is fed to a cylinder in proportion to the air mass induced in the cylinder. Air flow meter characteristics and fuel injector characteristics govern fuel control. The control parameters in the electronic controller should be tuned to the physical characteristics of the air flow meter and the fuel injectors during driving. Conventional development of the engine control system requires a lot of experiments for control parameter matching. The new matching method utilizes the deviation of feedback coefficients for stoichiometric combustion. The feedback coefficient reflects errors in control parameters of the air flow meter and fuel injectors. The relationship between the feedback coefficients and control parameters has been derived to provide a way to tune control parameters to their physical characteristics.
Technical Paper

A New Engine Control System Using Direct Fuel Injection and Variable Valve Timing

A new engine drivetrain control system is described which can provide a higher gear ratio and leaner burning mixture and thus reduce the fuel consumption of spark ignition engines. Simulations were performed to obtain reduced torque fluctuation during changes in the air - fuel ratio and gear ratio, without increasing nitrogen oxide emissions, and with minimum throttle valve control. The results show that the new system does not require the frequent actuation of throttle valves because it uses direct fuel injection, which increases the air - fuel ratio of the lean burning limit. It also achieves a faster response in controlling the air mass in the cylinders. This results in the minimum excursion in the air - fuel ratio which in turn, reduces nitrogen oxide emissions.
Technical Paper

Estimation of Particulate Matter in Direct Injection Gasoline Engines by Non-Combustion CFD

A technique of estimating particulate matter (PM) from gasoline direct injection engines is proposed that is used to compute mass density and particle number density of PM by using fuel mass in rich mixtures obtained by using non-combustion computational fluid dynamics (CFD). The CFD code that was developed by the authors employed a Cartesian coordinates system as a discretization method and large eddy simulation (LES) as a turbulence model. Fuel spray droplets were treated with the discrete droplet model (DDM). The code was verified with some experimental data such as those obtained from in-cylinder gas-flows with a laser Doppler velocimeter (LDV) and in-cylinder fuel concentration with laser induced fluorescence (LIF). PM emissions from a single-cylinder gasoline direct injection engine were measured with an electrical low pressure impactor (ELPI) to determine the model constants that were required in the estimation model.
Technical Paper

Wide-Range Air-Fuel Ratio Sensor, 1986

The oxygen ion conductive solid electrolyte cell served as a device for measuring the combustibles content and the oxygen content of an exhaust gas. The cell is comprised of a tubular electrolyte, two opposed electrodes and a porous diffusion layer located on the outer electrode surface. The sensor is employed to measure both rich and lean air fuel ratio through the use of an electronic circuit pumping the oxygen ions to achieve a constant voltage between the electrodes. The wide range detecting capability makes it particularly attractive for air fuel ratio control applications associated with the internal combustion engine. The result of the performance tests are as follows, Detecting range (air excess ratio λ) : 0.8 - “∞ Step response time constant (63%) : 200ms Warm up time. - less than 80 sec at 20°C We found in the durability test concerned with the heat cycle and contamination that if initial aging treatment is applied the output variation ratio (. λ/λ) is limited with in : 5%.
Technical Paper

Mineral Recovery Systems for Humans in a CELSS

The recovery of important minerals, salt (NaCI) and potassium (K), in a closed system, namely CELSS is discussed. NaCI is needed for humans, but is potentially harmful to plants. Salt is recovered after wet oxidation of urine. Since Na and K have similar chemical and physical properties, their recovery or separation may require sophisticated methods. Na, CI and K ions are separated from other ions by electrodialysis with univalent selective ion-exchange membranes and then NaCI is obtained separately by a crystalization process. Preliminary experiment on crystalization of NaCI-KCl mixed solutions showed a good separation result.
Technical Paper

Numerical Simulation System for Analyzing Fuel Film Flow in Gasoline Engine

A new numerical simulation system has been developed which predicts flow behavior of fuel film formed on intake port and combustion chamber walls of gasoline engines. The system consists of a film flow model employing film thickness as a dependent variable, an air flow model, and a fuel spray model. The system can analyze fuel film flow formed on any arbitrary three-dimensional configuration. Fuel film flow formed under a condition of continuous intermittent fuel injection and steady-state air flow was calculated, and comparison with experimental data showed the system possessing ability of qualitative prediction.
Technical Paper

Development of a Three-Dimensional Bird's-eye View Map Drawing Technique for Car Navigation Systems

In this paper, a newly developed three-dimensional (3D) bird's-eye view map drawing technique for car navigation systems is described. Conventional navigation systems give pseudo-perspective views which can not express ruggedness like hills and valleys. Our newly developed navigation system can display undulation of the land from viewpoints above and behind the current position, so that ups and downs of roads along with the driver's destination can be seen easily. The 3D-road map is not only effective during navigation but also during route planning, because it assists in searching for fine views before travel. In order to achieve the 3D-map view, we developed graphics software libraries, which work on a 32-bit RISC processor and on a low-cost graphics accelerator LSI with texture mapping capability. The graphics software libraries are constructed with three stages, the perspective projection stage, visible-surface determination stage, and rendering stage.
Technical Paper

Water Recycling System for CELSS Environment in Space

System configurations of water recycling for space use have been continued through theoretical and experimental studies. The water recycling system plays a central role in a Closed Ecological Life Support System (CELSS) which offers necessary environment and life styles in closed environment such as space stations, lunar bases, etc.. Membrane technology is a possible candidate for purifying waste water produced by crew use facility, plant cultivation facility, etc. In considerations of the system compactness realizing energy saving, membrane distillation has been revealed to be a suitable purification process. Ground experiments has been performed using membrane filtration processes and membrane distillation process. Thermopervaporation technology with hydrophobic membrane is utilized in the distillation process. The energy saving is achieved by thermal return of condensation energy.
Technical Paper

A Totally Integrated Vehicle Electronic Control System

A totally integrated vehicle electronic control system is described, which optimizes vehicle performance through use of electronics. The system implements efficient coordination of functions of the engine, drive-train, brakes, steering, and suspension control subsystems to give a smoother ride, better handling and greater safety. The principles of the system are based on control and stability augmentation strategies. Each subsystem has two observers which control the force of the actuators according to the vehicle dynamics. The system features a driver support system which allows the average driver to employ the full performance potential of the vehicle in exceptional situations, and an artificial response control system to ensure optimum response and comfort. Application of the system allows the driver to experience a new level of performance and a marked improvement in handling quality and ride comfort.
Technical Paper

Development of High Pressure Fuel Pump by using Hydraulic Simulator

We developed a high-pressure fuel pump for a direct injection gasoline engine and used a hydraulic simulator to design it. A single plunger design is the major trend for high-pressure fuel pumps because of its simple structure and small size. However, the single plunger causes large pressure pulsation and an unstable flow rate, especially at high engine speed. Therefore, a fuel-pipe layout that inhibits the pressure pulsation and a flow-rate control that stabilizes the flow are the most important challenges in pump design. Our newly developed hydraulic simulator can evaluate the dynamic characteristics of a total fuel supply system, which consists of pump, pipe, injector, and control logic. Using this simulator, we have improved fuel flow by optimizing the outlet check valve lift and the cam profile, and we reduced pressure pulsation by optimizing the layout of fuel pipes. Our simulation results agreed well with our experimental results.
Technical Paper

Spray Atomization Study on Multi-Hole Nozzle for Direct Injection Gasoline Engines

We investigated the size of fuel spray droplets from nozzles for direct injection gasoline (DIG) engines. Our findings showed that the droplet size can be predicted by referencing the geometry of the nozzle. In a DIG engine, which is used as part of a system to reduce fuel consumption, the injector nozzle causes the fuel to spray directly into the combustion chamber. It is important that this fuel spray avoid adhesion to the chamber wall, so multi-hole injection nozzles are used to obtain spray shape adaptability. It is also important that spray droplets be finely atomized to achieve fast vaporization. We have developed a method to predict the atomization level of nozzles for fine atomization nozzle design. The multi-hole nozzle used in a typical DIG injector has a thin fuel passage upstream of the orifice hole. This thin passage affects the droplet size, and predicting the droplet size is quite difficult if using only the orifice diameter.