Search Results

The authors have developed a measurement technique using a new digital telemeter which measures the piston secondary motion as ensuring high accuracy while under the operation. We applied this new digital telemeter to several measurements and analysis on the piston secondary motion that can cause piston noises, and here are some of the results from our measurement. We have confirmed that these piston motions vary by only several tenths of millimeter changes of the piston specifications such as the piston-pin offset and the center of gravity of the piston. As in other cases, we have found that a mere change of pressure in the crankcase or the amount of lubricating oil supplied on the cylinder bore varies the piston motion that may give effect on the piston noises.

The advantages of gasoline direct-injection are intake air cooling due to fuel vaporization which reduces knocking, additional degrees of freedom in designing a stratified injection mixture, and capability for retarded ignition timing which shortens catalyst light-off time. Stratified mixture combustion designs often require complicated piston shapes which disturb the fluid flow in the cylinder, leading to power reduction, especially in turbocharged gasoline direct-injection engines. Our research replaced the conventional shell-type shallow cavity piston with a dog dish-type curved piston that includes a small lip to facilitate stratification and minimize flow disturbance. As a result, stable stratified combustion and increased power were both achieved.

Previous reports have already described the details of engine start-shock and the mechanism of vibration mechanism in a stationary vehicle. This vibration can be reduced by optimized engine and motor generator vibration-reduction controls. A prediction method using a full-vehicle MBD model has also been developed and applied in actual vehicle development. This paper describes the outline of a new method for the hybrid system of mechanical power split device with two motors that predicts engine start-shock when the vehicle is accelerating while the engine is stopped. It also describes the results of mechanism analysis and component contribution analysis. This method targets engine start-shock caused by driving torque demand during acceleration after vehicle take-off. The hybrid control system is modeled by MATLAB/Simulink. A power management and motor generator control program used in actual vehicles is installed into the main part of the control system model.

Researches and developments of electronic transmission control have been made along with the progresses of electronical technologies in order to meet the requirements of decreasing fuel consumption as well as improving drivability. And nowadays many kinds of electronically controlled transmissions have been applied to a variety of cars. In this paper, a history of electronic transmission control from the first control systems mounted on TOYOTA CORONA in 1970s for the first time in the world to the newest ones having a lock-up function for fluid coupling (Torque Converter) as well as progresses of the respective electronical transmissions to their practical uses will be explained.

The use of ceramic insulation to reduce engine heat loss and thus improve fuel economy was examined but found to be detrimental rather than advantageous. This paper analyzes the reasons and presents an alternative approach, namely minimizing the heat transfer area. Experiments were conducted to determine the effects of surface smoothness on BSFC, output torque, heat release rate and piston temperature. It was found that with a mirror-finished combustion chamber, heat loss is decreased and consequently engine output is raised, while fuel consumption is lowered. The percentage reduction in heat loss was ascertained by numerically simulating combustion and was confirmed by FEM analysis of piston thermal distribution.

This paper describes the preliminary development of an on-board integration network for vehicle dynamics. The underlying philosophy is explained and the basic requirements are set forth. A design conforming to these requirements is presented and the experiments conducted to optimise the physical layer are described. An original token passing protocol is proposed for the access method and evaluated in comparison with the contention method by means of a specially devised simulation system.

Semi-active suspension is one of many effective devices to improve vehicle stability, controllability and riding comfort. A practical means to realize semi-active suspension is to vary the damping force of the shock absorber. In this paper, we propose a new type of shock absorber using a piezoelectric sensor and actuator. The piezoelectric sensor and actuator are built into the piston rod which is a part of the shock absorber. The piezoelectric element provides a fast response and a high actuation force. We used the piezoelectric element in shock absorbers in order to take advantage of these two features. High level compatibility between stability, controllability and riding comfort is expected, since damping force changes very quickly using this new type of shock absorber. In this paper, several topics are discussed. First, a general description of the damping force control system with simple configuration is explained.

A new automatic transmission, engineered from concept for “intelligent” and “anti-aging” (long life), has been designed and developed for TOYOTA's luxury passenger car, LEXUS LS400. This system, which has resulted in silky-smooth shift quality without changes in the long term, is composed of a transmission computer that interacts with engine computer, a number of sensors, an electronically controlled hydraulic unit with linear solenoid valves and assorted devices. As new control logic being developed with the aid of computer simulation to achieve distinction, the hydraulic and engine controls are combined in this system. There is a “feedback control”, where the clutch pressure is controlled according to the rate of acceleration and compensated for dispersion to applied pressure, engine torque and/or the coefficient of dynamic friction of clutches, and at the same time engine torque is reduced by retarding ignition timing.

This paper describes the development of one-piece die cast magnesium steering wheel frame for a steering wheel incorporating an air bag system. The light weight magnesium frame was designed to have proper stiffness, strength and characteristics of energy absorption. Magnesium alloys with various aluminum contents were tested, and AM60B alloy was selected because of its favorable properties of strength and elongation. New manufacturing techniques, for example, a vacuum hot chamber die casting system and a surface defect inspection system were developed in order to produce high quality castings. The characteristics of energy absorption were evaluated in the laboratory and on actual vehicle crash test, and the results were satisfactory. The magnesium steering wheel frame is about 45% (550g) lighter than the steel one. It has been in production in Toyota passenger cars with driver side air bags.

Recently, the quietness of the passenger compartment has become an important quality for a vehicle, and as a result, various improvements have been made to reduce the passenger compartment noise level. Particularly engine noise, a major source of interior noise, has been studied for many years and has recently been reduced to an acceptable level. As a result, air intake noise, which was a relatively minor noise source in the past, has rapidly become a noticeable noise source. This paper describes a newly developed air intake system testing apparatus, which enables us to evaluate intake noise at an early stage of engine development and also describes how the new apparatus and approach was used to develop a low-noise air intake system. This apparatus, called the PULSATION SIMULATOR, reproduces intake pulsations in the actual engine using its cylinder head and reproduces intake air flow precisely.

The effects of high boiling point fuel additives on deposits were investigated in a commercial turbocharged direct injection gasoline engine. It is known that high boiling point substances have a negative effect on deposits. The distillation end points of blended fuels containing these additives may be approximately 15°C higher than the base fuel (end point: 175°C). Three additives with boiling points between 190 and 196°C were examined: 4-tert-Butyltoluene (TBT), N-Methyl Aniline (NMA), and 2-Methyl-1,5-pentanediamine (MPD). Aromatics and anilines, which may be added to gasoline to increase its octane number, might have a negative effect on deposits. TBT has a benzene ring. NMA has a benzene ring and an amino group. MPD, which has no benzene ring and two amino groups, was selected for comparison with the former two additives.

Over the last few decades, in-cylinder visualization using optically accessible engines has been an important tool in the detailed analysis of the in-cylinder phenomena of internal combustion engines. However, most current optically accessible engines are recognized as being limited in terms of their speed and load, because of the fragility of certain components such as the elongated pistons and transparent windows. To overcome these speed and load limits, we developed a new generation of optically accessible engines which extends the operating range up to speeds of 6000 rpm for the SI engine version, and up to in-cylinder pressures of 20 MPa for the CI engine version. The main reason for the speed limitation is the vibration caused by the inertia force arising from the heavy elongated piston, which increases with the square of the engine speed.

In Biodiesel Fuel Research Working Group(WG) of Japan Auto-Oil Program(JATOP), some impacts of high biodiesel blends have been investigated from the viewpoints of fuel properties, stability, emissions, exhaust aftertreatment systems, cold driveability, mixing in engine oils, durability/reliability and so on. This report is designed to determine how high biodiesel blends affect oil quality through testing on 2005 regulations engines with DPFs. When blends of 10-20% rapeseed methyl ester (RME) with diesel fuel are employed with 10W-30 engine oil, the oil change interval is reduced to about a half due to a drop in oil pressure. The oil pressure drop occurs because of the reduced kinematic viscosity of engine oil, which resulting from dilution of poorly evaporated RME with engine oil and its accumulation, however, leading to increased wear of piston top rings and cylinder liners.

Hybrid vehicles (HVs) are becoming more widely used. Since HVs supplement engine drive with motor power, the lubricant oil temperature remains at a lower level than in a conventional gasoline vehicle. This study analyzed the effect of cylinder bore temperature and lubricant oil temperature on engine friction. The results showed that, although the lubricant oil temperature was not relevant, the bore temperature had significant effect on piston friction. It was found that raising the temperature of the middle section of the cylinder bore was the most effective way of reducing piston friction.

A new engine cooling fan system has been developed, in which the fan is driven by a hydraulic pump and motor and controlled electronically by a computer. By utilizing the hydrostatic power under precise control, the fan generates not only high airflow volume but also optimum flow rate for the various engine conditions. Also in this system, a relatively high efficiency is gained because the clearance between the tip of the fan blade and a shroud designed to be short, thanks to the installation of the fan on the radiator. As the result of these functions, the following features have been obtained which are superior to conventional fan systems like a engine-driven fan with fluid coupling or an electric-motor fan. (1) Reduced fan noise (2) Improved fuel economy (3) Small size and light weight

A new ABS and Traction control system (TRAC system) has been developed and put into mass production in a new model LEXUS LS400. The TRAC system controls Sub-Throttle Valve and brake hydraulic pressure independently for left and right wheels. To realize the ABS and TRAC system,it is necessary for the Electronic Control Unit (ECU) to process complex algorithm and high speed calculation. The ABS and TRAC ECU for LEXUS LS400 is constructed by 3 TOYOTA custom 8-bit single chip microcomputers. Each CPU performs wheel speed calculation,ABS control and TRAC control,sharing the common data through high speed serial communication. This paper describes the function of each CPU,the method of CPU communication and fail safe function in the ECU.

We adopted the active hydropneumatic suspension and the dual-mode 4WS system for the 1989 Toyota CELICA. The active control suspension system detects the vehicle state with various sensors to control the oil pressure in the hydraulic cylinder with the linear pressure control valve; controlling attitude, ride comfort, stability & controllability and three-level vehicle height. The 4WS system continuously changes the steering angle ratio between the front and rear wheel according to the vehicle speed, decreasing the minimum turning radius at a low speed by 0.5 m and improving the controllability at a medium speed and the stability at a high speed. In addition, we further improved the performance of each system by integrally controlling the active control suspension system and the 4WS system. Thus, we succeeded in improving the total performance of vehicle dynamics by adding ABS to these systems to control the vertical, lateral and longitudinal accelerations.

This paper describes how the 2-degree-of-freedom control concept may be applied to an active front-and-rear steering control system. The configuration of the system is explained as is the manner in which the control strategy can be devised. Simulation and test results confirm that vehicle characteristics may be varied to achieve specific aims and that steering response and vehicle stability can be independently improved.

This report relates to that kind of rumble generated in the passenger compartment during acceleration which is caused by intake noise. The rumble is a rough, unpleasant noise that comes into the passenger compartment during acceleration. This noise was reported to be caused by the resonant bending vibration of the crankshaft. However, the writer and associates found that intake noise from the air inlet could also cause the rumble in the passenger compartment as reported herein. By a modal analysis of the air column vibration generated in the inlet system parts and analysis of the air column vibration response to the force input from each cylinder, the writer and associates determined that the standing wave generated in the surge tank was the cause of the rumble. By modifying the shapes of surge tank models for computer simulation that had been used in predicting booming noise, etc., it became possible to predict rumble level due to intake noise through calculation.

As a part of a project to develop high performance, compact and lightweight vehicle radiators, a highly corrosion resistive fin has been developed, especially for use in the salt-laden environment. It is a thin plate with a mutual diffusion layer of Cu-Zn formed on either surface. Owing to this composite structure, not only the corrosion resistance is double that of Cu-Sn alloy fins that are currently in use with a thickness over 20% smaller than the latter (38 μm vs 50 μm), but the corrosion of the bonding solder has been reduced to one half because the Cu-Zn diffused layer has brought about substantial reduction in the fin's surface potential.