Search Results

In recent years, the number of reported traffic accidents due to sudden deterioration in driver’s physical condition has been increasing, it is expected to develop a system that prevents accidents even if physical condition suddenly changes while driving, or reduces damage through vehicle body control. For this purpose, it is necessary to detect sudden changes of the driver’s physical condition, and research is being conducted widely. Among them, it is reported that some of such changes may appear in the heartbeat interval. In other words, by acquiring the driver’s heartbeat interval in real time, it may be possible to detect the sudden changes, and reduce traffic accident. Even if a traffic accident occurs, the damage can be reduced by emergency evacuation immediately after detecting sudden changes.

Recently, for the protection of the environment, the regulation of automobile fuel consumption and exhaust gas emission has been strengthened. To improve fuel economy, it is demanded that each engine part contributes to reducing the workload of the engine, even the engine lubrication oil pump. In response to this, a new variable discharge oil pump was developed. It is the world's first internal gear type oil pump that has electronically controlled continuously variable discharge. The work performed by the pump chiefly takes two forms: sliding friction of the rotor and pumping work which moves the oil. First, in developing a variable discharge oil pump, a new tooth profile of the rotor was developed to reduce its sliding friction. As a result, the sliding friction of the rotor was reduced by 34% while maintaining the same theoretical oil discharge rate. Next, a variable discharge mechanism using an internal gear was developed.

Over the past decades, the automotive industry has made significant efforts to improve engine fuel economy by reducing mechanical friction. Reducing friction under cold conditions is becoming more important in hybrid vehicle (HV) and plug-in hybrid vehicle (PHV) systems due to the lower oil temperatures of these systems, which results in higher friction loss. To help resolve this issue, a new internal gear fully variable discharge oil pump (F-VDOP) was developed. This new oil pump can control the oil pressure freely over a temperature range from -10°C to hot conditions. At 20°C, this pump lowers the minimum main gallery pressure to 100 kPa, thereby achieving a friction reduction effect of 1.4 Nm. The developed oil pump achieves a pressure response time constant of 0.17 seconds when changing the oil pressure from 120 kPa to 200 kPa at a temperature of 20°C and an engine speed of 1,600 rpm.

1 There are two design challenges of the flow path switching valve in a three-stage variable discharge oil pump. The first is to obtain the required discharge pressure characteristics and the other is to prevent hydraulic vibration. Therefore, we established technologies to determine the shape of the valve and the valve housing that resolve these two challenges. The technology to obtain the required discharge pressure characteristics solves equations that are statically true, such as the equations for the equilibrium of forces and hydraulic orifice. The hydraulic vibration control technology derives a differential equation that takes transient behavior, including oil elasticity and inertia, into account first. Then, the derived equations are converted to a transfer function that indicates the valve behavior according to the input of oil pressure changes. And then the stability criterion is applied to judge whether hydraulic vibration occurs or not.

Recently, for the aspects of ecology and economy, fuel efficiency improvement demand has been increased globally. And, various types of hybrid systems have been suggested. In response to this market demand, AISIN SEIKI has been developing Synchronizer-less hybrid automated manual transmission (HV-AMT) system aiming excellent transmission efficiency, excellent agility, and shift change quality like a step automatic transmission (AT). This hybrid system is constructed based upon a parallel 2-axis manual transmission (MT) which originally has high transmission efficiency. The synchronizer system of a MT is replaced by a Dog clutch system which does not spoil the transmission efficiency and never makes failure in synchronization. This Dog clutch system includes a modified detent function, a shift actuator of linear motor, advanced function controls for a clutch and a shift actuator.

This paper reports that estimation accuracy of suspension stroke velocity is increased by considering the damping force delay characteristics to an observer. Thereby ride comfort is improved, using the simple and low-cost semi active suspension systems that use only three vertical acceleration sensors.

This paper reports the results of a study into a preview control that uses the displacement of the road surface in front of the vehicle to improve for front and rear actuator responsiveness delays, as well as delays due to calculation, communication, and the like. This study also examined the effect of a preview control using the eActive3 electric active suspension system, which is capable of controlling the roll, pitch, and warp modes of vehicle motion.

Clutch judder phenomenon is known as a vehicle vibration caused by the drive torque fluctuation from the clutch unit at takeoff. In this paper, a novel strategy for improving clutch judder phenomenon caused by the movement/tolerance between mechanical parts comprising the clutch system is introduced. In order to simulate the movements of the clutch system and of the vehicle drivelines precisely, we used numerical analysis software and have achieved high-grade prediction of the clutch torque fluctuation and the vehicle vibration. Using this method, we have developed a high-quality clutch system that enables smoother clutch engagement, and at the same time, development efficiency has been improved.

We have developed Sensor-less Memory Seat system that requires no position sensors such as Hall ICs etc.. It detects the rotation of DC motor by current ripple signals in motor operating current. The developed Sensor-less position control system can attenuate a wide frequency variation of Motor current noise which varies depending on motor condition and convert small current ripples to Pulse signals in proportion to the rotation of DC motor. We realized low cost position control method for use in Memory Seat system.

Switched Reluctance Motor (SRM) mainly has two advantageous characteristics such as no magnet and simple construction. These characteristics contribute lower cost and higher reliability compared with other motor systems such as brushless permanent magnet motors or induction motors. However, SRM has disadvantages that are its torque ripple and acoustic noise in particularly. Moreover, the resonance frequency mode of a motor system is excited by torque ripple, and drive train vibration is caused. These noise and vibration should be suppressed when the SRM is applied to a traction system for passenger electric vehicle since these characteristics affect vehicle quietness and drivability. In this paper, we describe an approach to suppress drive train vibration and acoustic noise.

Sport Utility Vehicles (SUV) and light duty trucks have gained in popularity for the last several years and the demand for more car-like behavior has increased, accordingly. Two areas for potential improvement are vehicle stability and maneuverability while parking. 4WS (4 wheel steering system) is known as an effective solution to stability and low speed maneuverability. In this paper, we identify a new systematic design method of two degree of freedom vehicle state feedback control algorithm that can improve vehicle stability, and show its control effects for a SUV with trailer towing. Low speed maneuvering is improved when the rear tires are steered in negative phase relative to the front tires. However with a large rear steer angle at low speed, the vehicle's rear overhang tracks a wider swing-out path than a 2WS vehicle. For this concern, we propose a new swing-out reduction control algorithm.

The metal top is used for convertible cars since the exterior design when the rooftop is closed is also important. A retractable metal top system which can automatically retract and extract the metal top has been popular to increase commercial values for the luxury convertible cars. We have developed the metal top open-close system comprising metal top,package tray and luggage panel operation link-mechanism units driven by electric motors. The metal top can be retracted or extracted in approximately 25 seconds by controlling the metal top system and the side and quarter window motors. The roof panel is pre-load so that the cabin air-tightness for high speed driving is maintained. The metal top is compactly retracted since the slide and side package trays are synchronized. Enough luggage space is secured using the multi-link mechanism to open and close the luggage panel. This retractable metal top system is equipped with the LEXUS SC430. (Fig.1) [1]

One of the problems concerning T/M is conventionally how “Improving the input torque as the engine gets higher power” and “Making product lighter in weight and more compact to improve the fuel consumption” can be realized at the same time. To realize these things at the same time, it is needless to say that the gears must be stronger. For the “pitting fatigue strength” which is quoted as a problem lately, the fatigue mechanism has not been clarified, yet. Therefore, it is now a big problem how to achieve high strength. In the meantime, we tried to develop the production engineering for “finer crystal grains” and “fine-dispersion precipitation of carbo-nitrides,” and succeeded in improving “pitting fatigue strength” remarkably. Such results will be reported in the following sections:

Switched Reluctance Motor (SRM) mainly has two advantageous characteristics such as no magnet and simple construction. These characteristics contribute lower cost and higher reliability compared with other motor systems such as brushless permanent magnet motors or induction motors. However, acoustic noise and output torque ripple should be improved when the SRM is applied to a traction system for passenger electric vehicle since these characteristics directly affect vehicle quietness and drivability. In this paper, we describe a system configuration of the SRM traction system for passenger electric vehicle. The SRM traction system includes an electric motor, transmission gears and power inverter module. Then, an approach to improve acoustic noise and output torque ripple is introduced. Generation mechanisms of acoustic noise and output torque ripple are analyzed.

We have developed a power sliding door (PSD) system driven by a push-pull cable. The door closure and slide are operated by different actuators to limit the force required for a compact, light-weight drive unit. This paper introduces the concept of the PSD system using a push-pull cable drive. Two new technologies to achieve the PSD system are also described. One is the door position control for increasing the push-pull cable reliability. The other is a compact position sensor to accurately detect the sliding door's position.

Chassis control systems, including ABS, traction control and vehicle stability control, utilize the available tire forces to improve vehicle acceleration, deceleration, handling and stability for active safety. Thus, it can be very beneficial to evaluate the tire force characteristics on actual road surfaces and use this information in the chassis control systems. In this paper, the research activities on evaluating the tire force characteristics and the performance of chassis control systems are introduced. The test procedure described for measuring the tire force characteristics on actual road surfaces using a test vehicle is relatively easy. The brake and side force characteristics are shown from the experimental data. The tire force characteristics during ABS braking were measured on various road surfaces. ABS performance is discussed based on the measured tire force characteristics.

Rear steering system can improve vehicle stability using active control of the rear wheel angles. For designing the rear steering system, environmental conditions, performance deterioration due to aging and component variation as a result of manufacturing tolerance under mass production must be taken into consideration. We have applied two-degree-of-freedom (2DOF) feedback control with feedforward control for the motor servo control so that the rear steering actuator can track the target rear steering angle accurately and stably. The control system is designed based upon a nominal mathematical model and its variation range. As a result, the rear steering actuator can be controlled with excellent performance and high reliability. This paper describes the mathematical model construction in the frequency domain and a robust motor servo controller design based on 2DOF feedback control with feedforward control.

Resolving the brake squeal that occurs under various environments is a major topic, and a resolution method is eagerly anticipated. We focused on the phenomenon that, amid various environmental conditions, squeal occurs easily when an automobile has been left standing in a cold environment. We checked the details focusing on the friction coefficient (hereafter, μ). As a result, we found that μ increases when squeal is generated, and that the sliding surface film contributes to the μ behavior. We studied measures to be taken to increase the μ in cold conditions.

In this paper, we discuss vehicle directional stability and introduce advanced stability control (ASTC) to stabilize the vehicle during severe cornering. Vehicle behavior in a transient steering condition during severe cornering was analyzed by computer simulation. It was found that applying an external yaw moment makes the vehicle more stable. The effect of controlling the brake force response is also evaluated by simulation to determine the brake actuator response criteria. The actual vehicle test was performed with a pylon slalom using a hydraulic brake actuator. It is verified that the ASTC stabilizes the vehicle for transient steering maneuvers.

This active-drive wheel speed sensor, developed by the high-frequency magnetic system, enables detection of very slow wheel speeds - hitherto difficult to accomplish with any conventional type of Magnetic Pick up - by applying the eddy current effect through the high-frequency magnetic field. The following report presents an analysis of the magnetic circuit which integrates the magnetic-field generating coil with the detection rotor, and the unique circuit system which ensures strength against eccentricity of the wheel rotor and air gap variations, etc.