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Generally, automobiles have many performance requirements for comfort, of which noise, vibration and harshness are very important. Toyota Motor Corporation equipped several 2003 models with the second-generation Electronically Controlled Brake system (ECB2). These ECB2 actuator units adopted a new structure that reduced pumping noise by controlling the skew phenomena of needle roller bearings. Normally, needle roller bearings are advantageous over other bearings in cases where a large force is loaded on bearings, because the contact areas can be made larger. However, a thrust force arises from skew phenomena because of minute clearances among the component parts of needle roller bearings. As a result, axial vibration of the bearing shaft sometimes occurs due to the thrust force. This paper explains how the thrust force generated from the skew phenomena of needle roller bearings occasionally affects the pumping vibration level of equipped machinery such as the brake actuator unit.

This paper presents a new application of a vehicle on-board battery charger utilizing high frequency Silicon Carbide (SiC) power devices. SiC is one of the most promising alternatives to Silicon (Si) for power semiconductor devices due to its superior material characteristics such as lower on-state resistance, higher junction temperature, and higher switching frequency. An on-board charger prototype is developed demonstrating these advantages and a peak system efficiency of 95% is measured while operating with a switching frequency of 250 kHz. A maximum output power of 6.06 kW results in a gravimetric power density of 3.8 W/kg and a volumetric power density of 5.0 kW/L, which are about 10 times the densities compared with the current Prius Plug-In Si charger. SiC technology is indispensable to eco-friendly PHV/EV development.

The development of electric vehicles has been progressed, rapidly, to achieve Carbon neutrality by 2050. There have been increasing concerns about Electromagnetic Compatibility (EMC) performance due to increasing power for power trains of vehicles. Because same power train system expands to some vehicles, we have developed numerical simulations in order to predict the vehicle EMC performances. We modeled a vehicle which has inverter noises by numerical simulation to calculate electric fields based on GB/T18387. We simulated the common mode noise which flows through the shielding braid of the high voltage wire harnesses. As a result, it is confirmed a correlation between the electric fields calculated by numerical simulation and the measured one.

Toyota developed a new hybrid unit “L4A0” for the new Tundra, which creates both good drivability and environmental performance. To ensure off-road, towing performance and typical truck driving characteristics, the unit is based on a transmission with a torque converter and a multi-plate lock up clutch, with a motor-generator and K0 clutch installed between the engine and transmission. The motor-generator and K0 clutch are built into a module, making it possible to create new hybrid units by combining the module with various transmissions. The unit features many different motor controls. For example, in the case of step-in acceleration input, in order to achieve the desired output torque, typically a kick-down shift is necessary [1]; however, by utilizing “L4A0” both high response and high power output is achieved even without a kick-down shift. This is accomplished by assisting the engine with the motor-generator even when the engine torque is delayed at low engine speeds.

In today's motorized society, various automotive technologies continue to evolve every day. Amid this trend, a new concept with respect to automatic transaxle gear-shifting has been developed. In order to materialize a new concept for shifting operation with a universal design in mind, a system has been developed: a shift-by-wire system developed specifically for hybrid vehicles. The greatest advantage of this new system is the lack of constraints associated with the conventional mechanical linkage to the transaxle. This allows freedom of design for the gear selection module. A revolutionary improvement in the ease of shifting has been realized by taking full advantage of this design freedom. In addition, this system contributes to an innovative design. For improved ease of operation, the operation force of the shift lever of this system has been dramatically reduced. For parking, the driver can engage the parking mechanism of the transaxle at the touch of a switch.

The purpose of this paper is to construct the thermal analysis model by measuring and estimating the temperature at the traction contact area. For measurement of temperature, we have used a thin-film temperature sensor. For estimation of temperature, we have composed the thermal analysis model. The thin-film temperature sensor was formed on the contact surface using a spattering device. The sensor is constituted of three layers (sensor layer, insulation layer and intermediate layer). Dimensions of the sensor were sufficiently smaller than the traction contact area. The sensor featured high specific pressure capacity and high speed responsiveness. The thermal analysis model was mainly composed of three equations: Carslaw & Jaeger equation, Rashid & Seireg equation and heat transfer equation of shear heating in oil film. The heat transfer equation involved two models (local shear heating model at middle plane, homogeneous shear heating model).

The Rx400h, which was put on the market in 2005, realized overwhelming power performance with the adoption of a high-voltage system, high-power output motor, and 3-motor type 4WD. Toyota has been working on a solution to increase the output power of the motor, i.e., the development of system stabilization technology. This paper introduces high-speed power balance control, which keeps the balance of power constant regardless of rapid changes in the number of motor rotations resulting from slipping tires or other factors, along with sensor error compensation control, which suppresses cyclic power fluctuation resulting from errors in the position sensor of the motor.

An obstacle recognition algorithm for the Pre-Crash Safety system has been newly developed with a stereo vision system and a millimeter wave radar with additional functions. This algorithm uses the merits of both the millimeter wave radar and the stereo vision system, and has two main features. One feature utilizes the merits of the stereo vision system detection with the detection results from the millimeter wave radar allowing for a more detailed horizontal position and width of the obstacle. This enables the equipment to operate at an earlier stage according to how well the relationship between the vehicle and the obstacle is understood. Another feature fuses detection from the millimeter wave radar and the stereo vision system. This system has succeeded in enhancing the detection performance of pedestrians who have been more difficult to detect than reflective objects such as cars.

Introducing effective technologies to reduce carbon emissions in the transport sector is a critical issue for automotive manufacturers to contribute to sustainable development. Unlike the plug-in electric vehicles (PEVs), whose effectiveness is dependent on the carbon intensity of grid electricity, the solar hybrid vehicle (SHV) can be an alternative electric vehicle because of its off-grid, zero-emission electric technology. Its usability is also advantageous because it does not require manual charging by the users. This study aims at evaluating the economic, environmental, and usability benefits of SHV by comparing it with other types of vehicles including PEVs. By setting cost and energy efficiency on the basis of the assumed technology level in 2030, annual cost and annual CO2 emissions of each vehicle are calculated using the daily mileage pattern obtained from a user survey of 5,000 people in Japan and the daily radiation data for each corresponding user.

In recent years, automakers have been developing various types of environmentally friendly vehicles such as hybrid (HV), plug-in hybrid (PHV), electric (EV), and fuel cell (FCV) vehicles to help reduce greenhouse gas (GHG) emissions. However, there are few commercial solar vehicles on the market. One of the reasons why automakers have not focused attention on this area is because the benefits of installing solar modules on vehicles under real conditions are unclear. There are two difficulties in measuring the benefits of installing solar modules on vehicles: (1) vehicles travel under various conditions of sunlight exposure and (2) sunlight exposure conditions differ in each region. To address these problems, an analysis was performed based on an internet survey of 5,000 people and publically available meteorological data from 48 observation stations in Japan.

There is ever increasing interest in the issues of fossil fuel depletion, global warming, due to increased atmospheric CO2, and air pollution, all of which are due in some extent to transportation, including automobiles. Hybrid Vehicles (HVs), whose performance and usage are equivalent to existing conventional vehicles, attract lots of attention and have started to come into wider use. Meanwhile, EVs have been considered by many as the best solution for the issues mentioned above. But the technical difficulty of battery energy density is an obstruction to successful implementation. Currently the Plug-in HV (PHEV), which combines the advantages of HV and EV, is being considered as one promising solution. PHEVs can be categorized into two types, according to operating modes. The first uses battery stored energy initially, only stating the internal combustion engine when the battery is depleted. This we call the All Electric Range (AER) system.

In this paper, we will introduce a stereo vision system developed as a sensor for a vehicle's front monitor. This system consists of three parts; namely, a stereo camera that collects video images of the forward view of the vehicle, a stereo ECU that processes its output image, and a near-infrared floodlight for illuminating the front at night. We were able to develop an obstacle detection function for the Pre-Crash Safety System and also a traffic lane detection function for a Lane-Keeping Assist System. Especially in regard to the obstacle detection function, we were able to achieve real-time processing of the disparity image calculations that had formerly required long processing times by using two types of recently developed LSIs.

This study analyzed the longitudinal vibration of a vehicle body and unsprung mass. Calculations and tests verified that longitudinal vibration can be reduced using in-wheel motors, which generate torque very quickly. Despite increasing demand for measures to enhance ride comfort considering longitudinal vibration, this type of vibration cannot be absorbed or controlled using a conventional suspension. This paper describes the reduction of vehicle longitudinal vibration that cannot be controlled by conventional actuators.

Given a forecast of speed and load demands during a trip, a hybrid powertrain power-split Trajectory Optimization Problem (TOP) can be solved to optimize fuel consumption. This can be done on desktop to set performance benchmarks; however, it has been believed that the TOP could not be solved in real-time and is not a realizable controller. As such, several approximations of the TOP have been made in the interest of obtaining a real-time near-optimal controller, for example, Equivalent Consumption Minimization Strategies (ECMS) and their adaptive counterparts. These strategies decide on the power-split by, at each sampled time instant, minimizing a Horizon-0 (without predicting forward in time) composite function of fuel consumption and equivalent battery energy. The fuel economy that results from these strategies is highly sensitive to the calibration of the associated equivalence factor, and furthermore, must be chosen differently for different drive cycles.

Toyota Safety Sense is a safety system package developed to help drivers avoid accident types with a high frequency of occurrence. This paper deals with pre-collision system which forms the core of Toyota Safety Sense, especially Toyota Safety Sense P which uses a combined sensor configuration consisting of a monocular camera paired with millimeter wave radar, in order to achieve both high recognition performance and reliability. The use of a wide-angle monocular camera, millimeter wave radar integrated in the front grill emblem, and a collision determination algorithm for pedestrian targets enabled the development of a pre-collision system comprising detection capability of crossing pedestrians. Toyota has developed warning and pre-collision brake assist for driver to assist in avoiding a collision effectively; In addition, Pre-collision brake has achieved high level of performance for the drivers who cannot avoid a collision.

The increase in automobile accidents has heightened the awareness of safety in the general public, and serious safety measures have been pushed forward in various countries. Although those efforts have achieved a certain level of success, more effective methods are needed to cope with further increases of automobile ownership.Besides the collision safety, measures that prevent accidents or reduce the possibility of accidents will now be necessary to reduce the number of injuries.Here, we will present the current development status and issues for an obstacle recognition system that reduces the likelihood of accidents by utilizing radars and image sensors.

In recent years, attention is being given to 42V power supply technology for solving the problem of increased power demand in vehicles. Since 2001, Toyota Motor Corporation has been marketing a mild hybrid system (THS-M) in order to further improve fuel economy and reduce emissions; this system requires both 42V and 14V power sources. The THS-M system consists of a 42V motor generator (M/G) connected to the engine crankshaft with a belt; an inverter; a 36V battery; a DC/DC converter for stepping down the 42V power supply to a conventional 12V battery; and high-power related electrical components. These components require additional costs, which must be reduced in order to increase the sales volume of THS-M vehicles. We have devised a method to eliminate the conventional DC/DC converter from the THS-M, and as a result we have developed a new, revolutionary power conversion system (multi-function inverter).

For a luxury sedan, quietness is a major selling point, and a hybrid luxury sedan is expected to be especially quiet. Therefore, in the development of the hybrid luxury sedan, every possible effort is needed to reduce the hybrid system noise in order to ensure a level of quietness far superior to that of an ordinary gasoline-powered vehicle. In addition, the noise and vibration phenomena that are particular to vehicles with longitudinal power trains require special reduction technologies. This paper first describes the superior quietness of hybrid luxury vehicles in comparison with ordinary gasoline-powered vehicles. This paper then addresses the development issues of vibration during engine starting, engine booming noise, and motor noise, explaining the mechanisms by which they are generated and the technologies employed to reduce them.

The new gasoline hybrid car, “the Prius”, has achieved both two-liter class power performance and world top-class gas mileage with the new Toyota Hybrid System “THS II”. Compared with the previous THS, the electric motor drive power of the THS II has been boosted by 50% and the weight of this system has been reduced by 20%. This paper describes the NV problems caused by the improvements to the hybrid system, and the countermeasures for them. It also describes the technologies for reduction of engine start vibration. Finally an evaluation method and countermeasures against interior engine noise are described.

Toyota has been introducing several hybrid vehicles (HV) since 1997 as a countermeasure to the concerns raised by automobile, like CO2 reduction, energy security, and pollutant emission reduction in urban areas. Plug in hybrid Vehicle (PHV) uses electric energy from grid rather than fuel for most short trips and therefore presents a next step forward towards an even more effective solution for these concerns. For longer trips, the PHV works as a conventional hybrid vehicle, providing all the benefits of Toyota full hybrid technology, such as low fuel consumption, user-friendliness and long cruising range. This paper describes a newly developed plug-in hybrid system and its vehicle performance. This system uses a Li-ion battery with high energy density and has an EV-range within usual trip length without sacrificing cabin space.