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Technical Paper

Future Trend of Instrument Cluster (Black Face Cluster)

1998-10-19
98C023
In 1989, the first black face cluster was introduced as the first Lexus cluster and has been highly praised in the market. The cluster has strong advantages but could not gain a higher installation ratio in various vehicles because of the cost. DENSO Corp. has been improving the cost performance of this cluster and the installation ratio is being increased. On the other hand, multi-information displays and component integration in instrument panels will soon be introduced. Considering this, I would like to discuss the future trend of instrument clusters using the black face cluster concept with multi displays and integration capabilities.
Technical Paper

Development of Laser Radar Cruise Control System

1998-10-19
98C003
The adaptive cruise control (ACC) system reduces the workload of the driver. Lower cost and more precise control are the keys to successfully creating a market with the ACC system. A system that eliminates unexpected acceleration or deceleration caused by incorrect judgment is in high demand. From 1997, the laser radar ACC system has been produced for the domestic version of the Lexus LS400. It provides high recognition capability with a two-dimensional scanning system at an affordable price. Th millimeter wave radar ACC system can perform with better recognition capability, but is quite expensive. While many companies are developing millimeter wave radar ACC systems, we think our laser radar ACC system is superior.
Technical Paper

Development of High Efficiency Rectifier with MOSFET in “eSC Alternator”

2017-03-28
2017-01-1228
Alternator, which supplies electric energy to a battery and electrical loads when it is rotated by engine via belt, is one of key components to improve vehicle fuel efficiency. We have reduced rectification loss from AC to DC with a MOSFET instead of a rectifier diode. It is important to turn on the MOSFET and off during a rectification period, called synchronous control, to avoid a current flow in the reverse direction from the battery. We turn it off so as to remain a certain conduction period through a body diode of the MOSFET before the rectification end. It is controlled by making a feedback process to coincide with an internal target conduction period based on the rotational speed of the alternator. We reduced a voltage surge risk at turn-off by changing the feedback gain depending on the sign of the time difference between the measured period and the target.
Technical Paper

Development of a New MOS Rectifier for High-Efficiency Alternators

2017-03-28
2017-01-1240
For the purpose of improving vehicle fuel efficiency, it is necessary to reduce energy loss in the alternator. We have lowered the resistance of the rectifying device and connecting components, and control the rectifying device with an IC to reduce rectification loss. For the package design, we have changed the structure of the part on which the rectifying device is mounted into a high heat dissipation type. The new structure has enabled optimizing the size of the rectifying device, resulting in the reduction of size of the package. In addition, the rectifying device is mounted using a new soldering material and a new process, which has improved the reliability of the connection. Moreover, since the alternator has introduced a new system, the controller IC has a function for preventing malfunction of the rectifying device and a function for detecting abnormalities, in order to ensure safety.
Technical Paper

Analysis of Dynamic Characteristics of Full-Pitch-Winding Switched Reluctance Motor Based on Reluctance Network Analysis

2017-03-28
2017-01-1250
An electromagnetic and motion-coupled analysis is made for a Switched Reluctance Motor (SRM) based on a Reluctance Network Analysis (RNA). A full-pitch-winding SRM is promising since it has a high torque density. Since the motor characteristics such as driving torque significantly depend on commutation pattern, an analysis coupled with motor motion and its drive circuit is requisite for the performance prediction. However, in the full-pitch-winding SRM, the relationship between the coil magnetomotive force and the core flux is complicated, and thus Finite Element Method (FEM) has been major method to predict the motor characteristics, which takes too much computational time for cycle calculations. An RNA treats the relationship of coil magnetomotive force and core flux as lumped parameter circuit, and thus enables fast computation with a macroscopic view of magnetic phenomena.
Technical Paper

Development of New Generation Battery Management ECU

2017-03-28
2017-01-1203
Recent electric vehicles use Li-ion batteries to power the main electric motor. To maintain the safety of the main electric motor battery using Li-ion cells, it is necessary to monitor the voltage of each cell. DENSO has developed a battery Electronic Control Unit (ECU) that contributes greatly to the reduction of the cost and the improvement of the reliability of the system. Each manufacturer has been developing a dedicated IC for monitoring the voltages of each cell of a battery. However, since the number of cells that can be monitored is limited, more than one IC is required to measure the voltages of a large number of cells. The increase in the number of ICs and the amount of insulator leads to the rise in system cost. DENSO has developed a dedicated IC that uses a proprietary high-breakdown voltage process, and which enables monitoring up to 24 cells with a single IC chip.
Technical Paper

Realizing Robust Combustion with High Response Diesel Injector with Controlled Diffusive Spray Nozzle and Closed Loop Injection Control

2017-03-28
2017-01-0845
The Diesel engine performance was drastically improved since the introduction of the Common Rail system in 1996. Over the years, the Common Rail technology was continuously improved to reduce the fuel consumption, engine-out emissions and enhance the drivability. However further technical improvement steps for a precise control of combustion are required to satisfy the increasing stringent worldwide emissions limits and to contribute to attractively performing Diesel powered vehicles. Common Rail injectors significantly contribute to improve the combustion. This improvement can be achieved by precisely controlling the injected fuel quantity and increasing the injection pressure. In addition to those features, a more rectangular injection rate, the capability of stable multiple injections at shorter intervals and the control of the spray shape, are required to achieve an optimized fuel mixture.
Technical Paper

ECU Structure Strategy to Detect Lift Timing of GDI Solenoid Injectors with High Precision

2017-03-28
2017-01-1628
In gasoline direct injection (GDI) systems, various injection types are needed to reduce emissions and improve fuel consumption. This requires high-precision injection in the region in which the amount of injection is small. Achieving injection of a small amount of fuel using GDI solenoid injectors requires the use of the half-lift region. In this region, however, the variation in the injection amount tends to increase due to the variation in the lift behavior of the injectors, posing the problem of how to achieve high-precision injection. To reduce the variation, we analyzed the lift timing out of the injector current and voltage signal with the ECU in an attempt to adjust the amount of injection.
Technical Paper

Development of Automatic Braking System to Help Reduce Rear Impacts

2017-03-28
2017-01-1408
A Rear Cross Traffic Auto Brake (RCTAB) system has been developed that uses radar sensors to detect vehicles approaching from the right or left at the rear of the driver’s vehicle, and then performs braking control if the system judges that a collision may occur. This system predicts the intersecting course of approaching vehicles and uses the calculated time-to-collision (TTC) to control the timing of automatic braking with the aim of helping prevent unnecessary operation while ensuring system performance.
Technical Paper

A Fixed-quantity Indicator to Replace Display Annoyance in an Indirect Field of Vision

2017-03-28
2017-01-1370
Driving is an action that depends strongly on visual information. For displays in the cockpit, a combination of “ease of viewing” to inform the driver of danger early and “annoyance reduction” to avoid drops in the driver’s perception is needed. In this study, we tried to capture “ease of viewing” and “annoyance” in one fixed-quantity indicator. We took up a Camera Monitor System (CMS) as the subject and analyzed the effect that annoyance with the display used in CMSs has on driving behavior. Based on our analysis, we hypothesize that evaluating carelessness in viewing behavior is related evaluating to annoyance. Next, we chose a Detection Response Task (DRT) technique as a method to evaluate driving behavior influenced by this annoyance.
Technical Paper

New Spray Concept Development for Dual Injection System

2017-03-28
2017-01-0835
Gasoline direct injection (GDI) systems are a main development focus for global environment issues and energy security. At the same time, it is also important to challenge further development of Multi point injection (MPI) systems for a simple and robust combustion system responding to global fuels ,required for the growing automotive markets in emerging countries, especially in the A, B vehicle segments. This paper focuses on reducing wall wetting in cold conditions and maximizing mixture cooling by fuel vaporization (preventing knocking) in high load conditions as key development points of MPI systems. We propose a dual MPI system enhancing direct flow of spray into the combustion chamber to gain part of the benefit of GDI in addition to the homogeneity advantage of an MPI system. This dual MPI system requires finer atomization with at the same time robustness against intake airflow.
Technical Paper

Real Driving Emission Efficiency Potential of SDPF Systems without an Ammonia Slip Catalyst

2017-03-28
2017-01-0913
In order to comply with emission regulation, reach their profitability targets and minimise the in-use cost of their vehicles, OEMs are seeking solutions to optimise their aftertreatment systems. For Selective Catalytic Reduction (SCR) system engineers, one of the most important challenges is to reduce the system's cost, while keeping its high level of NOx emission reduction performance. Ways to achieve this cost reduction include 1. using an engine out NOx estimation model instead of a NOx sensor upstream of the SDPF (DPF coated with SCR) catalyst and 2. eliminating the Ammonia Slip Catalyst (ASC) downstream of the SDPF catalyst. Achieving these challenging targets requires actions on the complete SCR system, from the optimisation of mixing and uniformity in the SDPF catalyst to the development of robust controls. To face these challenges, a novel exhaust reverse flow concept with a blade mixer was developed.
Technical Paper

A Sense of Distance and Augmented Reality for Stereoscopic Vision

2018-04-03
2018-01-1036
Head-up displays (HUDs) give visual information to drivers in an easy to understand manner and prevent traffic accidents. Augmented reality head-up displays (AR-HUDs) display the driving information overlaid on the actual scenery. The AR-HUD must allow the visual information and the actual scene to be viewed at the same time, and a sense of depth and distance are key factors in achieving this. Binocular parallax used in stereoscopic 3D display is one of the most useful methods of providing a sense of depth and distance. Generally, stereoscopic 3D displays must limit the image range to within Panum’s fusional area to ensure fusion of the stereoscopic images. However, when using a stereoscopic 3D display for an AR-HUD, the image range must extend beyond Panum’s fusional area to allow the visual information and the actual scene to be displayed at the same time.
Technical Paper

Pressure Sensor Module for High Temperature,High Pressure, and Quick Response

2018-04-03
2018-01-0759
According to the advance of engine control development, demands for direct sensing of physical quantity have been growing. Regarding pressure sensing, key properties for direct sensing are robustness against high temperature and pressure, and response time in addition to accuracy. In this work, a pressure sensor module with these key properties was developed. First of all, a piezoelectric device was selected as a suitable sensing principle for the required properties because of its thermally stable piezoelectric effect and potential for simple installation structure. Regarding robustness against temperature, the sensor module was designed to form thermal isolation layer with outer housing which is optimized according to its application. Regarding robustness against pressure and response time, breakage of the piezoelectric element is the main technical issue.
Technical Paper

Maximizing Coasting of 48 V Vehicles with Cold-Storage Evaporator

2018-05-30
2018-37-0023
One of the main features of 48 V vehicles is the ability to coast at high speeds with the Internal Combustion Engine (ICE) off. This can be realized due to the high torque and power the 48 V motor-generator provides which allows a quick and smooth re-cranking of the ICE. The coasting feature reduces the fuel consumption depending on frequency and duration of the coasting events. This depends in turn on driving pattern, driving style, State-of-Charge of the 48 V and 12 V batteries and the air-conditioning (A/C) system. In summer, if the A/C runs with a mechanical belt-driven compressor, the cabin inlet air temperature from the evaporator inevitably increases during each coasting event as the ICE turns off and cannot operate the compressor. If the evaporator temperature reaches a certain threshold at which the cabin comfort is noticeably affected, the ICE is re-cranked for resuming air-conditioning.
Technical Paper

Modeling of Expert Driver’s Braking Behavior and Its Application to an Automatic Braking System

2009-04-20
2009-01-0785
Deceleration patterns of an expert driver will be formulated using the perceptual risk index for approach and proximity of a preceding vehicle as an example of comfortable braking pattern. It will be shown that the formulated braking pattern can generate smooth deceleration profile uniformly for many conditions of approaching conditions. In addition, brake initiation timing of expert driver will be successfully formulated using the alternative index. Finally, an automatic braking system will be proposed based on the formulated brake initiation model and the velocity profile. Twenty five expert drivers experienced the automatic braking installed in an experimental car. It will be shown that the proposed system can generate smooth profile and realize secure brake patterns based on subjective evaluation.
Technical Paper

Cold Storage Air Conditioning System for Idle Stop Vehicle

2013-04-08
2013-01-1287
The number of idle-stop vehicles is rapidly increasing in recent years, and air-conditioning technologies that extend engine stopped time while maintaining the cabin comfort are required. When the engine stops during idle- stop mode, the air conditioner also stops functioning. To maintain cabin comfort, the engine is restarted to work the air-conditioning cycle, which reduces the fuel saving effects. As a countermeasure, a cold storage air conditioning system has been proposed. The system extends engine non-operation time by using cold storage for generating cool air while the engine is stopped. We have integrated this technology into an evaporator, which is used in the air-conditioning cycle, and the system has a short cold storage period and a necessary cold release period. This report describes its concept and effects.
Technical Paper

Hexagonal Cell Ceramic Substrates for Lower Emission and Backpressure

2008-04-14
2008-01-0805
Stringent emission regulations call for advanced catalyst substrates with thinner walls and higher cell density. However, substrates with higher cell density increase backpressure, thinner cell wall substrates have lower mechanical characteristics. Therefore we will focus on cell configurations that will show a positive effect on backpressure and emission performance. We found that hexagonal cells have a greater effect on emission and backpressure performance versus square or round cell configurations. This paper will describe in detail the advantage of hexagonal cell configuration versus round or square configurations with respect to the following features: 1 High Oxygen Storage Capacity (OSC) performance due to uniformity of the catalyst coating layer 2 Low backpressure due to the large hydraulic diameter of the catalyst cell 3 Quick light off characteristics due to efficient heat transfer and low thermal mass
Technical Paper

Reliability of SiC-MOSFET for Hybrid Vehicle

2012-04-16
2012-01-0337
This paper describes the reliability of silicon carbide (SiC) MOSFET. We clarified the relation between the lifetime of the gate oxide and the crystal defects. We fabricated MOS diodes using thermal oxidation and measured their lifetimes by TDDB (Time Dependent Dielectric Breakdown) measurement. The wear-out lifetime is sufficient for hybrid vehicle but many MOS diodes broke in shorter time. The breakdown points were defined by Photo-emission method. Finally, we classified the defects by TEM (Transmission Electron Microscopy). A TSD (Threading Screw Dislocation) plays the most important role in the lifetime degradation of the gate oxide. The lifetime of the gate oxide area, in which a TSD is included, is shorter by two orders of magnitude than a wear-out breakdown. The mechanism by which threading dislocations degrade the gate oxide lifetime was not discovered. To explain the degradation, we assumed two models, the shape effect and the oxide quality degradation.
Technical Paper

Virtual Development of Engine ECU by Modeling Technology

2012-04-16
2012-01-0007
Along with the evolution of vehicle electronic systems from independent control in each domain system to the integration control of the whole vehicle system, ECU systems have become increasingly complicated and large-scale. This has made it extremely difficult to develop the entire system coherently and efficiently from the functional level down to implementation level. On the other hand, the development methodology focusing on single ECU system used today has been facing an additional challenge because of increasingly strict requirements for safety design based on multi-ECU systems. To address these challenges, we have been working on developing virtual development of Engine ECU by modeling technology. In order to achieve optimum electronic systems, it is necessary to build many real devices and evaluate the performance of systems. However, it is also becoming necessary to build virtual devices because of the increasingly complicated and large-scale systems.
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