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Increasing electric loads in a vehicle causes over-discharge of a battery and drag torque due to an alternator. This paper gives a system concept of vehicle electric power flow management to solve these issues. Its primary function includes preserving electricity in a battery, stabilizing electric bus voltage, interfacing with vehicle torque control system, and improving fuel economy. The key point to realize such a system is a unified structure. It offers ‘Plug and Play’ function for electric power management components. Newly developed Vehicle Electric Power Flow Management System (VEF ) totally controls electric power flow in a vehicle. VEF contains an Electric Power Manager and its functional sub-systems, and controls them with the key parameter ‘electric power’. The sub-system includes Generation, Storage, Conversion, and Distribution to the loads.

DENSO started a pilot demonstration of on-site methanation as “CO2 circulation plant” as proactive initiative for CO2 capture and storage/utilization (CCUS) technologies toward achievement of carbon neutrality by 2035 in our own business. The CO2 circulation plant was designed to capture CO2 primarily generated by the plant and recycle it as an energy source of the facility. We also started work on the development of electric swing CO2 adsorption (ESA) technology to achieve low-energy CO2 capture.

Automotive manufacturers are working towards protecting the global environment by using filters to reduce particulate matter (PM) emissions from their vehicles. There is a growing demand for sensors that detect the small amounts of PM leaking through these filters, as they can aid in performing on-board diagnostics (OBD) and monitoring the function of these filters. Currently, vehicles predominantly use an electric resistance type PM sensor, which applies a voltage between electrodes, collects PM, and senses the generation of PM path. However, in response to tightening regulations on PM-OBD, the response time of the sensor needs to be optimized. Furthermore, the fast response time must not degrade the poisoning resistance in order to ensure durability. To shorten sensor response time, we have developed a 20 μm-gap electrode structure using a cross-section of laminated alumina sheets with printed electrodes, which can form PM paths at small PM amounts.

We have achieved significant weight reduction for the MS (Multi-Tank Super Slim Structure) Evaporator (1)currently in production at DENSO CORPORATION. The evaporator of HVAC unit, located in the instrument panel, is a component of the aluminum heat exchanger used in automotive air conditioners. The new evaporator uses thinner quad-layer sheet material, thanks to optimization of the electrical potential among its outer filler metal, intermediate anodic layer and core. The evaporator is thus lighter than conventional evaporators, but retains equivalent corrosion resistance.

Having a light weight, a good heat conductivity and a good brazability, aluminum alloy is widely used for automotive heat exchanger systems. The major problem with Aluminum is perforation of the tube by pitting corrosion and corrosion protection is necessary in the field. In radiator and condenser systems using the the Nocolok brazing process given good corrosion resistance using cathodic protection with sacrificial anode made of Zn-sprayed onto tube or low corrosion potential fins etc. On the other hand, in drawn-cup type evaporators, that are fabricated from brazing sheet tubes in vacuum brazing method and then covered low electro-conductive drain water film in operation, the effect of cathodic protection by the anode fin is limited to a very small area. Therefore, this has been studied to improve self-corrosion resistance of the core in the brazing sheet tube.

In conventional automobile designs, a radiator and a condenser are typically configured and mounted independently of each other. We have developed a smaller and more powerful cooling module by integrating these two products into one piece. The new cooling module has been designed to share the fin material and to have an insulating slit and other means for effective prevention of heat loss that occurs due to thermal conduction between the radiator and the condenser1). In addition, as one of the key techniques for integrating fins, we studied thermal spraying of brazing filler to the tube material and were able to achieve a practical-level cooling module through use of high-performance fins, contributing largely to the efforts to create a more compact, higher performance cooling module.

In a conventional soldering process, solvents, such as chlorofluorocarbons (CFCs), have been necessary to remove the flux-residue after soldering. A new CFC-free fluxless soldering process has been developed to obtain high sealing ability even in a small soldering area. This new process utilizes a reducing atmosphere with an appropriate load and assembly orientation to solder the parts. Under this fluxless condition, it is found that appropriate loading and good solder-wettability of the upper part increase the wettability of the lower part.

Fuel atomization is known as an effective means of reducing the exhaust emissions of internal combustion engines. We have focused on a multiple-hole nozzle as a cost-effective atomization method that does not require any auxiliary devices or an external energy source to carry out atomization. In this report, we will discuss the facts that 1) the primary factors of atomization with the multiple-hole nozzle lie in the flow upstream of the nozzle, and 2) the atomization characteristics such as spray droplet diameter and spray spatial distribution when the factors which effect atomization with the multiple-hole nozzle are changed. As a result, with our newly developed 12-hole nozzle injector in an actual engine, we found an HC reduction effect greater than that of a conventional air-assist injector.

Through the years, aluminum automotive heat exchangers have been developed in order to have a high performance and a light weight. Therefore, the thickness of the aluminum sheets for the application has been reduced. As the brazeability declines with the reduction in thickness, fins having a thickness under 80μm may be difficult to secure a good brazeability. Therefore, we studied the brazeability to determine the limit of thickness using clad fins from 40 to 80μm. The fillet volume formed at the joints of the fin and tube decreased with the decreasing fin thickness and the Si content in both the filler metals and the core alloys. The suitable range of Si content in the filler metals and the core alloys to obtain a good brazeability decreased with the decreasing fin thickness. When the fins were thinner than the critical values, it was impossible to have a good brazeability.

Recently, automotive semiconductor devices need miniaturization. One of the most important technologies is the package which encapsulates devices. In addition, the outer shape of the package is needed to change according to the mounted space. Conventional devices are mounted in the case, and encapsulated with potting resin. However this package structure is difficult to miniaturize because the case size limit. This report describes the development of the packaging technology for miniature and particular outer shape. The devices are set in the cavity and molded to one package. The three-dimension flow simulation is applied to analyze the flow in the cavity. The results of simulation correspond with experimental results. The cavity structure and the mold resin can be optimized by the simulation.

As automobiles become quieter, wiper operation noise becomes more noticeable. Squeal noise is one type of wiper operation noise. It is a high-frequency self-excited vibration that is easily generated before and after the wiper reverses direction. In analyzing this vibration, squeal noise was observed using a rotary disk system. Then FEM was applied to deduce an equation of motion that reflects the observation results. The equation suggests material and configuration approaches toward reducing squeal noise. Potential measures include improvement in the blade damping coefficient, reduction in the coefficient of friction by surface treatment, and an increase in neck thickness, etc. Implementation of these measures reduced squeal noise.

In the field of heavy-duty diesel engines, which require lifetime durability and high fuel efficiency, there is a growing demand for increased injection pressure and increased flow rate inside injection holes. This trend makes it important to prevent cavitation erosion of injector nozzles. This paper aims to clarify the relation between cavitation behavior and erosion damage experimentally by visualizing the flow inside diesel nozzles and to establish a new method for predicting cavitation erosion. To visualize internal flow, authors used the large-scale transparent nozzle whose Reynolds number and Cavitation number were matched with those of the actual real-size nozzle. Direct observation showed that the form of the cavitation changed from string-type cavitation to film-type cavitation with increasing needle lift.

A response surface model of a diesel spray, parameterized by the internal geometries of a nozzle, is established in order to design the nozzle geometries optimally for spray mixing. The explanatory variables are the number of holes, the hole diameter, the inclined angle, the hole length, the hole inlet radius, K-factor and the sac diameter. The model is defined as a full second-order polynomial model including all the first-order interactions of the variables, and a total of 40 sets of numerical simulations based on D-optimal design are carried out to calculate the partial regression coefficients. Partial regression coefficients that deteriorate the estimate accuracy are eliminated by a validation process, so that the estimate accuracy is improved to be ±3% and ±15% for the spray penetration and the spread, respectively. Then, the model is applied to an optimization of the internal geometries for the spray penetration and the spray spread through a multi-objective genetic algorism.

Driving Automation Systems (DAS) are subject to complex road environments and vehicle behaviors and increasingly rely on sophisticated sensors and Artificial Intelligence (AI). These properties give rise to unique safety faults stemming from specification insufficiencies and technological performance limitations, where sensors and AI introduce errors that vary in magnitude and temporal patterns, posing potential safety risks. The Safety of the Intended Functionality (SOTIF) standard emerges as a promising framework for addressing these concerns, focusing on scenario-based analysis to identify hazardous behaviors and their causes. Although the current standard provides a basic cause-and-effect model and high-level process guidance, it lacks concepts required to identify and evaluate hazardous errors, especially within the context of AI. This paper introduces two key contributions to bridge this gap.

There is increasing demand for a finer atomization of fuel spray in order to improve the engine performance and mileage, reduce exhaust emissions and then improve the transient response. [1]. We are improving the shape of holes in order to enhance finer atomization. It is especially important to reveal the spray break-up process and droplet diameter quantitatively for a better development of holes shape. In this paper, we set our focus on a multiple-hole nozzle and developed a quantitative visible analysis method to investigate the spray break-up process and droplet diameter. With this method, index of the relationship between break-up process and droplet diameter was defined. And by re-shaping the holes and by arrangement of the holes, the break-up process and droplets diameter were investigated.

In an effort to protect the earth's environment, emission regulations in the diesel engine field are becoming increasingly strict. One way of meeting these regulations is to atomize the fuel spray by using a fuel injection system with high-pressure injection, which activates engine combustion. With current in-line pump systems, however, it is still possible to satisfy the demand for cleaner emissions by improving the fuel spray, through measures such as reviewing high-pressure injection and initiating improvements in the nozzle. This report describes the new in-line pump system for medium duty diesel engines to meet future emission regulations. In this report, we will describe how analytical technology, such as computer simulation, was used on the pump side to make improvements for higher injection pressure.

For further increase in thermal efficiency of heavy-duty diesel engines, flexible regulation of the heat release rate (HRR) profile combined with higher compression ratio could have more rooms to improve indicated thermal efficiency by overcoming various drawbacks relevant to higher compression ratio. A new ideal HRR profile, which starts as a kind of delta shape to fulfil the isobaric cycle from top-dead-center (TDC) and is followed by the significant increase in HRR to reach the maximum cylinder pressure in the retarded timing, was proposed. We call it as ‘High-heels’ HRR profile from its two-step-increase delta shape. To confirm the potential of the ideal HRR profile by utilizing a single- cylinder heavy-duty diesel engine, a variable fuel injection rate equipment, novel combustion chamber designs, and an offset orifices nozzle were investigated as the technologies for modifying HRR profile.

We have developed a novel capacitive acceleration sensor fabrication process by applying surface MEMS (Micro Electro-Mechanical System) technology and successfully introduced this process for volume production of a new super slim sensor. The new process uses the ICP-RIE(Inductively Coupled Plasma - Reactive Ion Etching) technology to etch single crystal SOI(Si on Insulator wafers. In this technology, vertical Si etching is followed by, lateral etching along the buried oxide to release the movable electrode. Because of a dry process, the new process does not cause the movable structures to stick to each other. Our process uses only three masks and reduces the sensor chip size to a half that of our conventional capacitive acceleration sensors.

We have developed a novel wafer process for capacitive sensing accelerometer using surface Micro Electrical Mechanical Systems (MEMS) technology and successfully applied to the fabrication process. Our new process combines with a single crystal SOI (Si on Insulator) wafer, high aspect ratio silicon etching and newly developed anhydrous HF/Alcohol etch process of silicon oxides. Although wet conditions such as HF/water etch occurs stiction of mobile structure, our anhydrous HF/Alcohol etch process technology occurs no stiction of mobile structures, because of gas phase (dry) process. In our process, we have achieved smaller-sized sensor chip compared to our conventional 2 axes accelerometer.