Search Results

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.

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.

Recently, the demands of vehicle owners have become more diversified. This is particularly true in the paint appearance of the vehicle. Responding to these demands Toyota has developed an ink jet painting system, Toyota Fantasy Print System. This system can illustrate practically any picture which the customer desires. The system utilized a subtractive method of paint mixture which mixes or piles up these four permeable inks. The development of durable ink as well as equipment which can efficiently and effectively apply the ink onto the required contoured surface.

In recent years, problems such as global warming, the depletion of natural resources, and air pollution caused by emissions are emerging on a global scale. These problems call for efforts directed toward the development of fuel-efficient engines and exhaust gas reduction measures. As a solution to these issues, performance improvements should be achieved on the oil that lubricates the sliding sections of engines. This report points to features required of future engine oil-such as contribution to fuel consumption, minimized adverse effects on the exhaust gas aftertreatment system, and improved reliability achieved by sludge reduction-and discusses the significance of these features. For engine oil to contribution of engine oil to lower fuel consumption, we examined the effects of reduced oil viscosity on friction using gasoline and diesel engines.

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 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.

Multi-dimensional code has been developed to simulate the effect of geometry on mass flow rate and flow pattern in the induction system of an internal combustion engine. The unsteady compressible Navier-Stokes equations in general curvilinear coordinates are solved by a new method of lines. In the method of lines, the governing equations are spatially discretized by a finite difference approximation and the resulting system of ordinary differential equations is integrated. As a time integration scheme, we newly propose to use the rational Runge-Kutta scheme in order to efficiently simulate the flows in the induction system. The domain-decomposition technique is introduced so that body-fitted structured grid can be easily generated for such complex geometry as a real intake port shape. The present code is applied to 2 and 3 dimensional steady flows in intake port/cylinder assembly with a valve.

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.

The world's first mass production gasoline hybrid passenger car, the “Prius”, was introduced into the Japanese market in 1997. By the time it was introduced into the American and European markets in Mid-2000, its fuel consumption and exhaust emissions had been further improved while achieving superior NV performance compared with conventional vehicles with 1.5-liter engines even in these competitive markets. This paper describes NV reduction technology for problems peculiar to the hybrid vehicle such as engine start/stop vibration, drone noise and vibration at low engine speed and motor/generator noise and vibration. It also compares the overall NV performance of the hybrid vehicle with conventional gasoline engine vehicles.

A method for predicting body deformation during operation, which cannot be measured by conventional methods, has been developed. The method creates a body model based on the characteristics extracted by modal analysis of the results of a vibration testing of an actual vehicle. The model is combined with a suspension model, using multibody dynamics software, and body deformation calculations are performed. In this paper, the influence of body deformation on vehicle controllability and stability is studied and the usefulness of the method is verified.

The growing functionality and complexity of recent vehicle electronic systems have made inter-device communication (on-board LAN) technology vital to vehicle design. By field of application, the LAN (Local Area Network) systems currently in use are LIN (Local Interconnect Network) used for body systems, CAN (Controller Area Network) used for control systems, and MOST (Media Oriented Systems Transport ) used for multimedia and camera systems, and work to standardize the next-generation communication technology for each of those fields is underway. This paper provides a technical overview of the CXPI (Clock Extension Peripheral Interface) communication protocol, which satisfies the body system requirements (rapid response, system extensibility, high reliability, and low cost). It also presents the progress made on standardization at SAE and other organizations.

Thermal load caused by engine combustion is one of the important issues for the engines such as high-boosted downsized engines and engines with high compression ratio. In particular, it is necessary to maintain the reliability and durability of exhaust valves which are subject to the biggest thermal impact. For this reason, sodium filled hollow valves are utilized in preference to solid valves in order to decrease the exhaust valve temperature. The most common method for detecting the valve temperature is to estimate the temperature by measuring hardness on valve surface (Hardness test). However, the hardness test is only applicable to the condition up to 800°C. Therefore, this paper presents new techniques for measuring the temperature for sodium-filled valve using infrared thermography and thermocouple as an alternative hardness test. The authors also examined the valve temperatures at a variety of engine speeds and cooling of the sodium-filled valve during engine operation.

Vehicles equipped with in-wheel motors (IWMs) are capable of independent control of the driving force at each wheel. These vehicles can also control the motion of the sprung mass by driving force distribution using the suspension reaction force generated by IWM drive. However, one disadvantage of IWMs is an increase in unsprung mass. This has the effect of increasing vibrations in the 4 to 8 Hz range, which is reported to be uncomfortable to vehicle occupants, thereby reducing ride comfort. This research aimed to improve ride comfort through driving force control. Skyhook damper control is a typical ride comfort control method. Although this control is generally capable of reducing vibration around the resonance frequency of the sprung mass, it also has the trade-off effect of worsening vibration in the targeted mid-frequency 4 to 8 Hz range. This research aimed to improve mid-frequency vibration by identifying the cause of this adverse effect through the equations of motion.

We developed new microalloyed steels, containing about 0.05% sulfur, which have excellent as hot-forged toughness even when forged at the temperatures of about 1300°C(2375°F). We also estimated the various properties of the new microalloy steel in the as hot-forged condition, comparing them to quench and tempered SAE1055 steel used in the front axle of a small truck. The results showed the new steel has improved yield strength, fatigue strength, absorbed impact energy and machinability over the SAE1055 steel.

This paper describes the development of a fatigue life prediction method for Laser Screw Welding (LSW). Fatigue life prediction is used to assess the durability of automotive structures in the early design stages in order to shorten the vehicle development time. The LSW technology is a spot-type joining method similar to resistance spot welding (RSW), and has been developed and applied to body-inwhite structures in recent years. LSW can join metal panels even when a clearance exists between the panels. However, as a result of this favorable clearance-allowance feature of LSW, a concave shape may occur at the nugget part of the joint. These LSW geometric features, the concavity of nuggets and the clearance between panels, are thought to affect the local stiffness behavior of the joint. Therefore, while assessing the fatigue life of LSW, it is essential to estimate the influence of these factors adequately for the representation of the local stiffness behavior of the joint.

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.

It is difficult to improve tire cavity noise since the pressure of cavity resonance acts as a compelling force, and its low damping and high gain characteristics dominate the vibration of both the suspension and body. For this reason, the analysis described in this article aimed to clarify the design factors involved and to improve this phenomenon at the source. This was accomplished by investigating the acoustic coupling vibration mode of the wheel, which is the component that transmits the pressure of cavity resonance at first. In addition, the vibration characteristic of suspension was investigated also. A speaker-equipped sound pressure generator inside the tire and wheel assembly was developed and used to infer that wheel vibration under cavity resonance is a forced vibration mode with respect to the cavity resonance pressure distribution, not an eigenvalue mode, and this phenomenon may therefore be improved by optimizing the out-of-plane torsional stiffness of the disk.