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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 proposes a novel method of verifying comprehensive driver model used for the evaluation of driving safety systems, which is achieved by coupling the traffic simulation and the driving simulator (DS). The method consists of three-step procedure. In the first step, an actual driver operates a DS vehicle in the traffic flow controlled by the traffic simulation. Then in the next step, the actual driver is replaced by a driver model and the surrounding vehicle maneuvers are replayed using the recorded data from the first step. Then, the maneuver by the driver model is compared directly with the actual driver's maneuver along the simulation time steps.

To reduce interior noise effectively in the vehicle body structure development process, noise and vibration engineers have to first identify the portions of the body that have high sensitivity. Second, the necessary vibration characteristics of each portion must be determined, and third, the appropriate body structure for achieving the target performance of the vehicle must be realized within a short development timeframe. This paper proposes a new method based on the substructure synthesis method which is effective up to 200Hz. This method primarily utilizes equations expressing the relationship between driving point inertance change at arbitrary body portions and the corresponding sound pressure level (SPL) variation at the occupant's ear positions under external force. A modified system equation was derived from the body transfer functions and equation of motion by adding a virtual dynamic stiffness expression into the dynamic stiffness matrix of the vehicle.

This paper describes the development and achievement of a target engine sound for a V6 SUV in consideration of the sound quality preferences of customers in the U.S. First, a simple definition for engine sound under acceleration was found using order arrangement, frequency balance, and linearity. These elements are the product of commonly used characteristics in conventional development and can be applied simply when setting component targets. The development focused on order arrangement as the most important of these elements, and sounds with and without integer orders were selected as target candidates. Next, subjective auditory evaluations were performed in the U.S. using digitally processed sounds and an evaluation panel comprising roughly 40 subjects. The target sound was determined after classifying the results of this evaluation using cluster analysis.

The renewed platform of the upcoming flagship front-engine, rear-wheel drive (FR) vehicles demands high levels of driving performance, fuel efficiency and noise-vibration performance. The newly developed driveline system must balance these conflicting performance attributes by adopting new technologies. This article focuses on several technologies that were needed in order to meet the demand for noise-vibration performance and fuel efficiency. For noise-vibration performance, this article will focus on propeller shaft low frequency noise (booming noise). This noise level is determined by the propeller shaft’s excitation force and the sensitivity of differential mounting system. In regards to the propeller shaft’s excitation force, the contribution of the axial excitation force was clarified. This excitation force was decreased by adopting a double offset joint (DOJ) as the propeller shaft’s second joint and low stiffness rubber couplings as the first and third joints.

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.

New engine controls have been developed for the turbocharged Lexus NX200t to improve driving power by reducing engine torque output lag. Drive power management functions have been centralized in an integrated drive power control system. The newly developed controls minimize the potential reduction in drivability associated with the adoption of a turbocharged engine while improving fuel efficiency. General driveability issues commonly associated with a turbocharged engine include sudden increases in drive power due to the response lag of the turbocharger, and higher shifting frequencies if this response lag triggers a disturbed accelerator operation pattern by the driver. The developed technologies detect and control sudden increases in drive power to create the optimum drive power map, and reduce unnecessary shifts even if the driver's accelerator operation is disturbed.

TOYOTA has developed a new automatic transmission, called the A341E. This transmission employs a unique engine and transmission integrated intelligent control system named “ECT-i”, and a high performance “Super Flow” Torque Converter. This control system is capable of total control of engine torque and clutch hydraulic pressure during shifting, which has resulted in very smooth shift without changes over the life of the transmission. The “Super Flow” Torque Converter has a modified geometry optimized by the analysis of internal flow by means of computer simulations, attaining the highest efficiecy in the world. With the use of such systems, this new automatic transmission has improved total performance of the vehicle.

The new eight-speed automatic transmission direct shift-8AT (UA80) is the first automatic transmission to be developed based on the Toyota New Global Architecture (TNGA) design philosophy. Commonizing or optimizing the main components of the UA80 enables compatibility with a wide torque range, including both inline 4-cylinder and V6 engines, while shortening development terms and minimizing investment. Additionally, it has superior packaging performance by optimizing the transmission size and arrangement achieving a low gravity center. It contributes to Vehicle’s attractiveness by improving driving performance and NVH. At the same time, it drastically improves fuel economy and quietness.

This paper presents a modeling method for prediction of low-frequency road noise in a steady-state condition where rotating tires are excited by actual road profile undulation input. The proposed finite element (FE) tire model contains not only additional geometric stiffness related to inflation pressure and axle load but also Coriolis force and centrifugal force effects caused by tire rotation for precise road noise simulation. Road inputs act on the nodes of each rib in the contact patch of the stationary tire model and move along them at the driving velocity. The nodes are enforced to displace in frequency domain based on the measured road profile. Tire model accuracy was confirmed by the spindle forces on the rotating chassis drum up to 100Hz where Coriolis force effect should be considered. Full vehicle simulation results showed good agreement with the vibration measurement of front/rear suspension at two driving velocities.

Toyota has developed a new 2.4L L4 turbo (2.4L-T) engine with 8AT and 1-motor hybrid electric powertrains for midsize pickup trucks. The aim of these powertrains is to fulfill both strict fuel economy and emission regulations toward “Carbon Neutrality”, while exceeding customer expectations. The new 2.4L L4 turbocharged gasoline engine complies with severe Tier3 Bin30/LEVIII SULEV30 emission regulations for body-on-frame midsize pickup trucks improving both thermal efficiency and maximum torque. This engine is matched with a newly developed 8-speed automatic transmission with wide range and close step gear ratios and extended lock-up range to fulfill three trade-off performances: powerful driving, NVH and fuel economy. In addition, a 1-motor hybrid electric version is developed with a motor generator and disconnect clutch between the engine and transmission.

Aisin AW (AW) and Toyota Motor Corporation (TMC) have developed a new RWD 6 speed automatic transmission, AWR6B45(AC60), suitable for SUV’s and LDT’s in the worldwide market, not only for North America but also for other countries including emerging nations. This 6 speed automatic transmission has achieved low cost, equivalent to AW and TMCs’ current 5 speed automatic transmission, while realizing improvement in both fuel economy and driving performance against current in-house 5-speed automatic transmissions, in addition to satisfying both toughness against various usage and light weight/compactness. They are accomplished by using a compact gear train structure, the latest efficiency improvement technologies, and a high-response, compact hydraulic control system. In addition, the compactness of this 6 speed automatic transmission enables it to replace current 4 speed and 5 speed automatic transmissions for various engine applications.

The purpose of this study is to propose braking characteristics that are easy for drivers to handle in a system in which braking and driving operations are performed by hand. Genetic algorithm optimization of braking characteristics showed that the best deceleration tracking was achieved by an FG diagram with a logarithmic function shape. In contrast, the slope of the optimal FG diagram tended to decrease as the driver's proportional gain increased.

This study aims at the development of a projection pattern that is capable of shortening the time required by a driver to perceive a pedestrian at night when a vehicle’s high beams are utilized. Our approach is based on the spatio-temporal frequency characteristics of human vision. Visual contrast sensitivity is dependent on spatiotemporal frequency, and maximum contrast sensitivity frequency varies depending on environmental luminance. Conventionally, there are several applications that utilize the spatio-temporal frequency characteristics of human vision. For example, the National Television System Committee (NTSC) television format takes into consideration low-sensitivity visual characteristics. In contrast, our approach utilizes high-sensitivity visual characteristics based on the assumption that the higher contrast sensitivity of spatio-temporal frequencies will correlate more effectively with shorter perception times.

We investigated a lighting method that supports pedestrian perception by vehicle drivers. This lighting method makes active use of visual characteristics such as the spatio-temporal frequency of contrast sensitivity. Using reasonable parameter values derived from preliminary experiments using a Campbell-Robson chart, we determined a suitable lighting pattern that improves the driver's pedestrian perception. In order to assess the influence of visual characteristics on a reaction-time-dependent task, such as pedestrian perception in nighttime, tests were performed in the target environment, the results of which validated the proposed method.

This article proposes a rubber suspension bushing model considering amplitude dependence as a useful tool at the initial design phase. The purpose of this study is not to express physical phenomena accurately and in detail and to explore the truth academically, but to provide a useful design method for initial design phase. Experiments were carried out to verify several dynamic characteristics of rubber bushings under vibration up to a frequency of 100 Hz, which is an important frequency range when designing ride comfort performance. When dynamic characteristic theory and the geometrical properties of the force-displacement characteristic curve were considered using these dynamic characteristics as assumptions, an equation was derived that is capable of calculating the dynamic stiffness under an arbitrary amplitude by identifying only two general design parameters (dynamic stiffness and loss factor) under a reference amplitude.

This paper describes impact kinematics and injury values of Hybrid III AM50, THOR AM50 and THUMS AM50 in simulated oblique frontal impact conditions. A comparison was made among them in driver and passenger seat positions of a midsize sedan car finite element (FE) model. The simulation results indicated that the impact kinematics of THOR was close to that of THUMS compared to that of the Hybrid III. Both THOR and THUMS showed z-axis rotation of the rib cage, while Hybrid III did not. It was considered that the rib cage rotation was due primarily to the oblique impact but was allowed by flexibility of the lumbar spine in THOR and THUMS. Lateral head displacement observed in both THOR and THUMS was mostly induced by that rotation in both driver seat and passenger seat positions. The BrIC, thorax and abdominal injury values were close to each other between THOR and THUMS, while HIC15 and Acetabulum force values were different.

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.

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 International Lubricant Standardization and Approval Committee (ILSAC) ATF subcommittee members have compared the two oxidation bench test methods, Aluminum Beaker Oxidation Test (ABOT) and Indiana Stirring Oxidation Stability Test (ISOT), using a number of factory-fill and service-fill ATFs obtained in Japan and in the US. In many cases, the ATFs were more severely oxidized after the ABOT procedure than after the same duration of the ISOT procedure. The relative severity of these two tests was influenced by the composition of the ATFs. The bench test oxidation data were compared with the transmission and the vehicle oxidation test data.