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Technical Paper

Development of Low Sulfated Ash and Fuel Economy Diesel Engine Oil

2009-06-15
2009-01-1845
A low sulfated ash (S.Ash) DL-1/C2 0W-30 diesel engine oil with improved fuel economy has been developed to meet the PM targets outlined in the Euro 5 emissions standards and to help achieve the voluntary European CO2 target of 140 g/km. The newly developed engine oil is an effective solution to the trilemma (triple probrem) of reliability (high detergency and high anti wear), low S.Ash, and fuel economy, achieving a fuel economy improvement of 2% and reducing CO2 emissions by 3 g/km.
Journal Article

Influence of Bio Diesel Fuel on Engine Oil Performance

2010-05-05
2010-01-1543
To evaluate the influence of FAME, which has poor oxidation stability, on engine oil performance, an engine test was conducted under large volumes of fuel dilution by post-injection. The test showed that detergent consumption and polymerization of FAME were accelerated in engine oil, causing a severe deterioration in piston cleanliness and sludge protection performance of engine oil.
Technical Paper

New Drivetrain for Toyota's Flagship Lexus LFA Sports Car

2011-04-12
2011-01-1427
Toyota Motor Corporation has developed a new drivetrain for their flagship Lexus LFA sports car. Passionate driving experience was pursued at the forefront of development. Superior vehicle performance, handling, and responsiveness that seem to anticipate the driver's intentions are achieved. Special vehicle packaging and component placement are adopted in the LFA in order to realize such performance. The engine, clutch, and front counter gear are positioned at the front of the vehicle, and the transaxle at the rear. The engine and transaxle are connected by a rigid torque tube. The transaxle is an automated manual transmission equipped with an electrohydraulic actuator for controlling both the shift and clutch operations. This actuator enables accurate control of the transmission and extremely quick response to shift paddle operation by the driver. This paper describes a general outline of the drivetrain and each component that has significantly contributed to LFA product appeal.
Journal Article

FEM System Development for Dynamic Response Analysis of Acoustic Trim

2009-05-19
2009-01-2213
The multilayer vehicle trim is well known for its effective influence upon noise and vibration characteristics not only in the high-frequency range but also in the low and mid-frequency ranges. FEM technologies which represent the accurate stiffness, mass and damping of trim parts such as the dash silencer and the floor carpet are essential in order to extend current body FEM capability to the road noise and the engine noise issues generated in the mid-frequency range. Conventional modeling methodologies such as local impedance and/or spring-mass modeling that express absorption and insulation properties of acoustic trim contain limitations in the mid-frequency range. There are few reliable FEM technologies to create practical vehicle models that represent the precise characteristics of the trim. In this paper, poroelastic modeling of acoustic multilayer trim was established by employing Biot theory.
Journal Article

A Custom Integrated Circuit with On-chip Current-to-Digital Converters for Active Hydraulic Brake System

2016-04-05
2016-01-0091
This paper presents a custom integrated circuit (IC) on which circuit functions necessary for “Active Hydraulic Brake (AHB) system” are integrated, and its key component, “Current-to-Digital Converter” for solenoid current measurement. The AHB system, which realizes a seamless brake feeling for Antilock Brake System (ABS) and Regenerative Brake Cooperative Control of Hybrid Vehicle, and the custom IC are installed in the 4th-generation Prius released in 2015. In the AHB system, as linear solenoid valves are used for hydraulic brake pressure control, high-resolution and high-speed sensing of solenoid current with ripple components due to pulse width modulation (PWM) is one of the key technologies. The proposed current-to-digital converter directly samples the drain-source voltage of the sensing DMOS (double-diffused MOSFET) with an analog-to-digital (A/D) converter (ADC) on the IC, and digitizes it.
Technical Paper

Indoor Pass-by Noise Evaluation System Capable of Reproducing ISO Actual Road Surface Tire Noise

2016-04-05
2016-01-0479
Generally, pass-by noise levels measured outdoors vary according to the influence of weather conditions, background noise and the driver’s skill. Manufactures, therefore, are trying to reproduce proving ground driving conditions on a chassis dynamometer. The tire noise that occurs on actual road surfaces, however, is difficult to reproduce in indoor tests. In 2016, new pass-by noise regulations (UN R51-03) will take effect in Europe, Japan and other countries. Furthermore, stricter regulations (2dB) will take effect in 2020. In addition to the acceleration runs required under current regulations, UN R51-03 will require constant speed runs. Therefore, an efficient measurement methods are necessary for vehicle development. To solve the above mentioned issues, an indoor evaluation system capable of reproducing the tire noise that occurs on road surfaces has been developed.
Technical Paper

Development of a Compact Adsorption Heat Pump System for Automotive Air Conditioning System

2016-04-05
2016-01-0181
In order to reduce the energy consumption of the automotive air conditioning system, adsorption heat pump (AHP) system is one of the key technologies. We have been developing compact AHP system utilizing the exhaust heat from the engine coolant system (80-100 °C), which can meet the requirements in the automotive application. However, AHP systems have not been practically used in automotive applications because of its low volumetric power density of the adsorber. The volumetric power density of the adsorber is proportional to sorption rate, packing density and latent heat. In general, the sorption rate is determined by mass transfer resistance in primary particle of an adsorbent and heat and mass transfer resistance in packed bed. In order to improve the volumetric power density of the adsorber, it is necessary to increase the production of the sorption rate and the packing density.
Technical Paper

Development of a New Valvetrain Wear Test - The Sequence IVB Test

2016-04-05
2016-01-0891
The study described in this paper covers the development of the Sequence IVB low-temperature valvetrain wear test as a replacement test platform for the existing ASTM D6891 Sequence IVA for the new engine oil category, ILSAC GF-6. The Sequence IVB Test uses a Toyota engine with dual overhead camshafts, direct-acting mechanical lifter valvetrain system. The original intent for the new test was to be a direct replacement for the Sequence IVA. Due to inherent differences in valvetrain system design between the Sequence IVA and IVB engines, it was necessary to alter existing test conditions to ensure adequate wear was produced on the valvetrain components to allow discrimination among the different lubricant formulations. A variety of test conditions and wear parameters were evaluated in the test development. Radioactive tracer technique (RATT) was used to determine the wear response of the test platform to various test conditions.
Technical Paper

Estimation of Driver Workload Based on a Model of Accelerator Pedal Control While Controlling Vehicle Velocity

2016-04-05
2016-01-1412
In driver-focused vehicle development, driver workload is generally evaluated subjectively, with physiological, psychological, and behavioral indexes used to quantify and substantiate the subjective rating. In contrast, a model of driver behavior expresses the driver’s behavioral characteristics which make it possible to estimate how the driver will incorporate information into vehicle operation. Therefore, it is presumed to be capable of estimating the internal state of a driver. Conventionally, a model of driver behavior related to pedal operation has been used for evaluating the driver’s habits and the acceptability of various types of support devices. However, it has not been used for estimating driver workload related to pedal operation. To examine driver workload, this study divided pedal operation magnitude into two components: a learning/judgment component and a correcting component for prediction errors. A method was devised of separating these two components.
Technical Paper

Toyota’s New Driveline for FR Passenger Vehicles

2017-03-28
2017-01-1130
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.
Technical Paper

Animal-Vehicle Encounter Naturalistic Driving Data Collection and Photogrammetric Analysis

2016-04-05
2016-01-0124
Animal-vehicle collision (AVC) is a significant safety issue on American roads. Each year approximately 1.5 million AVCs occur in the U.S., the majority of them involving deer. The increasing use of cameras and radar on vehicles provides opportunities for prevention or mitigation of AVCs, particularly those involving deer or other large animals. Developers of such AVC avoidance/mitigation systems require information on the behavior of encountered animals, setting characteristics, and driver response in order to design effective countermeasures. As part of a larger study, naturalistic driving data were collected in high AVC incidence areas using 48 participant-owned vehicles equipped with data acquisition systems (DAS). Continuous driving data including forward video, location information, and vehicle kinematics were recorded. The respective 11TB dataset contains 35k trips covering 360K driving miles.
Technical Paper

Feasibility Study of Drowsy Driving Prediction based on Eye Opening Time

2017-03-28
2017-01-1398
Since drowsy driving is a major cause of serious traffic accidents, there is a growing requirement for drowsiness prevention technologies. This study proposes a drowsy driving prediction method based on eye opening time. One issue of using eye opening time is predicting strong drowsiness before the driver actually feels sleepy. Because overlooking potential hazards is one of the causes of traffic accidents and is closely related to driver cognition and drowsiness, this study focuses on eye opening movements during driving. First, this report describes hypotheses concerning drowsiness and eye opening time based on the results of previous studies. It is assumed that the standard deviation of eye opening time (SDEOP) indicates driver drowsiness and the following two transitions are considered: increasing and decreasing SDEOP. To confirm the hypotheses, the relationship between drowsiness and SDEOP was investigated.
Technical Paper

Development of a New 6-Speed FWD Manual Transmission

2018-04-03
2018-01-0392
Environmental awareness has increased on a global scale which pushed for a heavier demand for weight reduction and high transmission efficiency on manual transmissions (hereafter referred to as the “MT”) in improving vehicle driving and fuel economy performance. Comfortable shift feel is also continuously in demand by the customer because its sensitive performance can be directly recognized by the driver which may determine the transmission’s merchantability. The newly developed 6-speed MT (hereafter referred to as the “6MT”) has achieved size reduction (compact size), weight reduced, better fuel efficiency, and improvement in the shift feel which will continue to maintain its’ competitiveness in the future.
Technical Paper

Development of New Continuously Variable Transmission for 2.0-Liter Class Vehicles

2018-04-03
2018-01-1062
Toyota has developed a new continuously variable transmission (CVT) called "Direct Shift-CVT" which is for 2.0-liter class vehicles. This CVT provided not only power transmission by a metal belt held with a conventional pulley but also additional gear mechanism. This CVT is developed to improve fuel efficiency, acceleration characteristic, and quietness. At this CVT, the startup low gear ratio is achieved by gear mechanism and the power is switched by clutches. Since the belt-pulley portion can be realized to be wide range by using only high gear ratio range, the input load into belt-pulley portion is reduced and unprecedented compact and high efficient belt-pulley portion is established. Consequently, the high efficiency in all fields from startup acceleration to high speed driving is achieved to improve fuel efficiency.
Technical Paper

Spatio-Temporal Frequency Characteristics Measurement of Contrast Sensitivity for Smart Lighting

2016-04-05
2016-01-1420
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.
Technical Paper

Factors in Annoyance Due to Windshield Reflection of the Outline of the Head-up Display

2016-04-05
2016-01-1417
The use of a head-up display (HUD) system has become popular recently, as it can provide feedback information at a position easily seen by the driver. However, the outline of the HUD bezel often reflects on the windshield of a HUD equipped vehicle. This phenomenon occurs when the sun is at a high position and reflects off the top of the instrument panel and the front view is dark. For this reason, it can occur when driving on asphalt paved roads, causing annoyance to the driver. Under fixed environmental conditions, the vehicle based factors that influence the annoyance caused by reflected boundary lines are the position of the reflection, line thickness, and the contrast of the reflected boundary line. These can be represented by the conspicuity of a striped pattern (contrast sensitivity function). In previous research in 1991, M. S. Banks et al. studied a contrast sensitivity function that included the factors stated above.
Technical Paper

Study on TTC Distribution when Approaching a Lead Vehicle

2016-04-05
2016-01-1452
In order to help avoid or mitigate rear-end collisions a Pre-Collision System (PCS) was developed. The purpose of this study is to clarify the Time-to-Collision (TTC) distribution when approaching a lead vehicle under normal driving condition. To enhance the effectiveness of PCS, warnings and/or automatic brake activation should happen as early as possible, however, if too early there is a high possibility of false warnings or activations, which is not desirable. If the distribution of distance to a lead vehicle under normal driving conditions is quantified, an approach limit can be estimated. In this study, we try to clarify a TTC distribution that is approximated by a log-normal distribution. Then, we investigate the Enhanced Time-to-Collision (ETTC) that is the secondary predictive value of TTC. And, we clarify the log-normal distribution of ETTC is a more stable approximator of normal driving than a log-normal distribution of TTC.
Technical Paper

Pre-Collision System for Toyota Safety Sense

2016-04-05
2016-01-1458
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.
Technical Paper

Thermal Management of a Hybrid Vehicle Using a Heat Pump

2019-04-02
2019-01-0502
This paper presents the thermal management of a hybrid vehicle (HV) using a heat pump system in cold weather. One advantage of an HV is the high efficiency of the vehicle system provided by the coupling and optimal control of an electric motor and an engine. However, in a conventional HV, fuel economy degradation is observed in cold weather because delivering heat to the passenger cabin using the engine results in a reduced efficiency of the vehicle system. In this study, a heat pump, combined with an engine, was used for thermal management to decrease fuel economy degradation. The heat pump is equipped with an electrically driven compressor that pumps ambient heat into a water-cooled condenser. The heat generated by the engine and the heat pump is delivered to the engine and the passenger cabin because the engine needs to warm up quickly to reduce emissions and the cabin needs heat to provide thermal comfort.
Technical Paper

Development of Strength Distributed Hot Stamp Parts

2019-04-02
2019-01-0522
1 Structural parts, such as the center pillar, are a multi-layer structure. They are a combination of high-strength panels and high-toughness panels, to control the deformation mode during a crash. If we can make this multi-layered structure as one panel, consisting of different hardness within it, we will be able to make a lightweight part. In this study, we have developed a method to fabricate a ‘lightweight center pillar’ with the following processes. First, the whole panel is hardened by quenching within the hot stamp process. Next, certain areas of the panel are softened by partial tempering. We have found that the temperature zone for softening is between A1 and A3, and it is easy to perform a rapid and accurate tempering by utilizing induction heating around the Curie temperature between A1 and A3 transformation temperature.
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