Search Results

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.

In Japan, from the viewpoint of ozone layer protection, specified CFCs (Chlorofluorocarbons) phase-out started in 1992 and completed by 1995. HFC-134a (Hydro fluorocarbon-134a) is now dominant in the market. HFC-134a, the replacement, has zero ozone depleting potential, while it still has a higher global warming potential (GWP = 1430). In this paper, efforts of DENSO and the Japanese industry from aspects of refrigerant emission reduction and energy efficiency improvement are introduced.

At present, various efforts are being made in the industrial world to preserve the earth's environment. Automobile industry has to comply with the emission control regulations including NOx and PM and the requirement of reducing CO2 emission from the viewpoint of global warming protection and energy saving. In these situations, diesel engines having a high potential to reduce CO2 emission are attracting much attention. In order to enhance the potential of diesel to reduce CO2 while solving its problems (“slow, dirty, noisy”), common rail systems are vital. DENSO developed an advanced common rail system (CRS) that integrates fuel injectors capable of delivering up to five injection events per combustion cycle at 180MPa injection pressure. This paper describes the injection performance and effects of the 180MPa common rail system and then explains the next generation common rail system.

Increased interest in global warming issues requires rapid improvements in reduction of CO2 emissions. The automotive industry is placing high importance on improving fuel economy performance across their entire product lines. Charging Management System is a necessary element towards fuel economy improvement. Many of today's charging management systems perform at least two important functions: improving efficiency based on vehicle motion, and detecting battery state of charge. These systems become more complicated as more components (i.e. generators, current sensors and ECU) and software are added. Therefore, it is difficult to develop charging management systems for an entire product line and difficult to retrofit the system for vehicles already in production. A stand-alone charging management system solves these issues. This system is independent of the other vehicle systems. The software for improving fuel economy is installed in the generator or current sensor.

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.

The direct injection diesel engine system was developed to solve the problems of conventional diesel engine systems: emissions of PM (Particulate Matter) and high emissions of NOx (nitrogen oxides). The common rail pressure sensor is a key sensor in the system, which requires high-pressure resistance of 160MPa and accuracy of ±1%. This paper discusses our development of a new generation of common rail system high-pressure sensors that are structurally simpler than conventional sensors, while meeting the above requirements.

Carbon brushes for automotive starters are used under severe conditions of high electric current density, high contact pressure and high sliding velocity. Therefore lead has traditionally been added to brushes to improve performance and durability. Lead is an environmental hazardous substance. In the EU, the law prohibits adding lead to brushes for electric motors which is installed on new automobiles in and after January 2005. In order to develop the lead free carbon brush for starters, we analyzed the effect and selected substitutive substance of lead. Adding lead to the brush reduces the electric resistance increase of the brush in high-temperature and high-humidity atmosphere and in high-temperature atmosphere. Furthermore lead reduces the wear amount of brush. We developed the lead free brush surpassing the lead addition brush in performance and durability by addition of lead alternatives silver and zinc.

Spray characteristics such as spray shape and spatial distribution of droplet diameter remarkably influences on output and exhaust emissions of direct injection gasoline engines. Especially, spatial distribution of the droplet diameter after impingement of a spray against a piston cavity is one of the most important factors for output and exhaust emissions, but is not revealed sufficiently because of the difficulties of measurement. In this paper, a new laser holography method that can obtain spatial distribution of droplet diameter over the spray in a short time was developed. And with this method, differences of spatial distribution of Sauter mean diameter (SMD) of droplets between before and after impingement on a flat wall in a high-pressure chamber were revealed using a prototype injector. Effects of impinging angle and distance against the wall on spatial SMD distribution were also investigated.

A DPNR (Diesel Particulate-Nox Reduction) system is designed to simultaneously remove PM (Particulate Matter) and NOx from the exhaust of diesel engined vehicles. A DPF (Diesel Particulate Filter) is used in the DPNR system to reduce the PM. The DPF must have high PM filtering efficiency, while at the same time having low back pressure. However, filtering efficiency and back pressure have trade off relations. Therefore, it is necessary to optimize the pore distribution in the walls of the DPF to satisfy both characteristics. This paper will explain that optimized control of pore distribution enables both high PM filtering efficiency and low back pressure.

The challenge for the diesel engines today is to reduce harmful emissions, such as particulate matter (PM) and Nitrogen oxides (NOx), and enhance the fuel efficiency and power, which are its main advantages. To meet this challenge, DENSO has developed an advanced common rail system (CRS) that uses piezo actuated fuel injectors capable of delivering up to five injection events per combustion cycle at 180MPa, currently the world's highest commercially available diesel fuel injection pressure. The DENSO piezo injector incorporates an internally developed piezoelectric element that energizes quicker than its solenoid counterpart, thereby reducing the transition time for the start and end of the fuel injection event. The piezoelectric element and unique passage structure of the DENSO injector combine to provide a highly reliable and responsive fuel injection event.

Conventional methods of physicochemical models require various experts and a high measurement demand to achieve the required model accuracy. With an additional request for faster development time for diagnostic algorithms, this method has reached the limits of economic feasibility. Machine learning algorithms are getting more popular in order to achieve a high model accuracy with an appropriate economical effort and allow to describe complex problems using statistical methods. An important point is the independence from other modelled variables and the exclusive use of sensor data and actuator settings. The concept has already been successfully proven in the field of modelling for exhaust gas aftertreatment sensors. An engine-out nitrogen oxide (NOX) emission sensor model based on polynomial regression was developed, trained, and transferred onto a conventional automotive electronic control unit (ECU) and also proves real-time capability.

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.

This paper proposes an oil degradation sensor that informs the best time for oil replacement to achieve the right balance with oil conservation and engine protection. We found that free radicals in the engine oil generate by chain decomposition reactions of hydrocarbons by heat and the amount of them increases with an increase in running distance. Based on theoretical analysis and experiment results, the free radical concentrations have high correlations with pH and base number. The sensor using the principle of electron spin resonance (ESR) can measure the amount of free radical molecules in a non-contact method. The sensor successfully detected free radicals produced by the degradation of actual engine oil.

Diesel engines have smoke trade-offs with both NOx and combustion noise. Both the increment of air entrainment into the spray and deceleration of heat release rate slope which become quickly thanks to the increase of air entrainment are effective for overcoming the trade-off between smoke emission and combustion noise. In this study, effect of quick rising injection rate and pre-injection was focused as an enabler for the both. The mechanism of improvement in the trade-off caused by the quick rising injection rate and pre-injection was clarified by analyzing characteristics of spray and combustion, interaction of pre-injected spray to main-injected spray and behavior of smoke emission. Some visualization techniques were adapted to analysis of sprays and combustions. Spray momentum measurement was used for the air entrainment and mixture formation process analyzation.

The set-off length (also referred to as the “lift-off length”) is reduced by the re-entrainment of the burned gas by the backward flow surrounding a diesel spray jet produced by a multi-hole nozzle. In the present study, to estimate the equivalence ratio at the set-off length, a means of estimating the amount of burned gas that is re-entrained into the near-nozzle region of the diesel spray jet was established. The results revealed that the suppression of soot formation in quasi-steady diesel spray flames produced by a multi-hole nozzle and a high injection pressure is not attained by reducing the equivalence ratio at the set-off length. Analysis of the amount of soot along the spray axis using a two-color method revealed that the maximum soot amount position appears in a quasi-steady spray flame, after the collapse of the head vortex in which a dense soot cloud is formed. The maximum soot amount position does not change even if the injection pressure varies.

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.

A hybrid powertrain offers the potential of a significant fuel saving for heavy-duty Diesel vehicles, which results in CO2 reduction of more than 20%, depending on the application. Using advanced future fuels, like HVO offers additional CO2 saving potential. In addition, the future Diesel engine needs to comply with the next generation of emission legislation, given by the European EUVII and the US EPA2027 regulatory frameworks. To achieve these limits, a combination of different technologies for the engine and the aftertreatment system are required. The proposed paper will present these technology solutions and their impact on CO2 and emissions by means of engine testing and simulation.

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.

Reducing vehicle CO2 emissions is an important measure to help address global warming. To reduce CO2 emissions on a global basis, Toyota Motor Corporation is taking a multi-pathway approach that involves the introduction of the optimal powertrains according to the circumstances of each region, including hybrid electric (HEVs) and plug-in hybrid electric vehicles (PHEVs), as well as battery electric vehicles (BEVs). This report describes the development of a new PHEV system for the Toyota Prius. This system features a traction battery pack structure, transaxle, and power control unit (PCU) with boost converter, which were newly developed based on the 2.0-liter HEV system. As a result, the battery capacity was increased by 1.5 times compared to the previous model with almost the same battery pack size. Transmission efficiency was also improved, extending the distance that the Prius can be driven as an EV by 70%.