Search Results

An active engine mount using a piezo actuator for a large vibrational amplitude is discussed. As a piezo actuator has a small displacement, the active mount requires a mechanism to increase the displacement of the piezo actuator to sufficiently counteract vibration. This paper describes in detail the construction of the prototype and the background theory from which the increase in displacement was achieved. Secondary, it describes a proving test performed on an experimental device that simulates the transfer of vibration from the engine to the chassis through the piezo active mounts. Finally it reports the decrease in floor vibration achieved when a piezo active mount was installed on an experimental vehicle.

The purposes of this paper are to develop a new laboratory oxidation stability testing method and to clarify factors relative to the viscosity increase of engine oil. Polymerized products, obtained from the oil after a JASO M333-93 engine test, were found to consist mainly of carboxyl, nitrate and nitro compounds and to increase the oil viscosity. A good similarity between the JASO M333-93 test and the laboratory simulation test was found for the polymerized products. The products were obtained not by heating oil only in air but by heating oil while supplying a synthetic blowby gas consisting of fuel pyrolysis products, NO, SO2 and air. The laboratory test has also revealed that the viscosity increase depends on oil quality, organic Fe content and hydrocarbon composition in the fuel. Moreover, it has been found that blowby gas and organic Fe accelerate ZnDTP consumption and that aromatics concentration in the fuel correlates with the viscosity increase of oil.

A multi-dimensional numerical method for predicting the warm-up characteristic of automobile catalytic converter systems was developed to effectively design catalytic converter systems which achieve low tail pipe emissions with satisfactory packagebility. The features of the method are; (1) consideration of the governing phenomena such as gas flow, heat transfer, and chemical reactions (2) capability of predicting warm-up characteristic for not only the catalytic converters but also the system as a whole during emission test modes such as the USA LA-4 mode. The description of the method is presented. The experimental verifications of the method were conducted to assure the accuracy of it. The effect of design parameters such as electrically heated catalyst (EHC), high loading of noble metal and thin honeycomb wall on warm-up characteristic of the catalyst are analyzed in the paper.

A new method to predict low-frequency brake squeal occurrence was developed and guidelines for its elimination were formulated. First, a characteristic of the phenomenon was investigated using a simplified three-degree-of-freedom system model to obtain guidelines for squeal elimination, such as the natural frequency ratio of the brake rotor and caliper, an equivalent mass ratio of the brake rotor and caliper and the natural frequency and damping coefficient of the dynamic absorber. Then, a practical finite element model of the disk brake system was developed using Substructure Synthesis Method for design stage predictions. Finally, the usefulness of this method was confirmed by experimental validation.

Three-dimensional numerical analysis of fuel liquid and mixture behavior in a port-injection gasoline engine is assessed by comparing calculations with measurements. The fuel mass distributed in the intake port and cylinder is measured using an engine with hydraulic valve and gas sampling system. The experimental results show that about half of the fuel mass per injection enters the cylinder, and the rest stays in the port. The difference of the mass fraction of injected fuel directly entering the cylinder is small between the cases of single pulse injection and serial injection. Therefore, three-dimensional calculation presupposing single pulse injection has difficulty in predicting the in-cylinder mixture formation process, although it can analyze the amount of fuel wetting the port wall. The calculations are performed for a port-injection engine, and the differences of fuel behavior with respect to swirl control valve opening and wall temperature are discussed.

This paper describes the multiplex communication protocol, BEAN (Body Electronics Area Network), developed for body control system on passenger cars which in recent years has increased the scope of multiplex communication. BEAN is based on a protocol developed in 1992 (SAE920231) but expands upon the performance in areas, such as the suitability of the ID system for increase of ECUs, the variable data length enabling the transmission of diagnostic data, and the transmission rate, while keeping the cost and radiation noise level low. The software size of BEAN is compact enough to be implemented by general purpose 8bit MCUs which have recently seen improvements in performance. The BEAN communication devices are available corresponding to the scale of the application and configuration of the ECU taking into account the software capability. This protocol was evaluated using simulation with the body control system on luxury passenger cars.

The compositions of hydrocarbons in diesel fuel, exhaust gas and particulates were analyzed and the relationships among them were determined. It was found that the compositions of the hydrocarbons in the exhaust gas were almost the same as that of the fuel, and that the hydrocarbons in the particulates corresponded to their heavy fractions. When the engine condition was fixed, both the soluble organic fraction (SOF) and insoluble fraction ( ISF) showed positive correlation coefficients versus HC×R310, where HC denotes the hydrocarbon emission and R310 denotes the backend fraction, as measured by the fraction of fuel boiling above 310°C. On the other hand, when the engine condition was varied, ISF had negative correlation coefficients versus HC×R310, while SOF showed positive correlation coefficients.

The effects of multiple-injection on exhaust emissions and performance in a small HSDI (High Speed Direct Injection) Diesel engine were examined. The causes for the improvement were investigated using both in-cylinder observation and three-dimensional numerical analysis methods. It is possible to increase the maximum torque, which is limited by the exhaust smoke number, while decreasing the combustion noise under low speed and full load conditions by advancing the timing of the pilot injection. Dividing this early-timed pilot injection into two with a small fuel amount is effective for further decreasing the noise while suppressing the increase in HC emission and fuel consumption. This is realized by the reduced amount of adhered fuel to the cylinder wall. At light loads, the amount of pilot injection fuel must be reduced, and the injection must be timed just prior to the main injection in order to suppress a possible increase in smoke and HC.

The authors developed a useful analysis method of the rotational-angle of gear under transient state using the Hilbert Transform because the conventional method was not available under the transient state. Here, under the transient state the gear revolution speed was changed from 600r/min to 2000r/min in 0.35 seconds. A key technology of this method was that Hilbert Transform method, which used to be applicable only for steady data was improved so that it could treat transient data. Hence, the following procedures were developed. 1. The rotation of gear-teeth was detected by a gap-sensor pair, which can cancel the measuring error due to fluctuation of gear shaft. 2. The frequency of such signals varied significantly by the gear-revolution speed. Transient gear-teeth detection signals obtained at a constant sampling rate were converted to almost-constant frequency signals over the data series axis using a trigger pulse obtained per gear revolution.

In order to reduce the interior noise of a vehicle with a four-cylinder engine, investigations were made using finite element and vector methods, acoustic intensity testing and holography technique. The investigation resulted in inclination of the engine mounting, design changes to the front suspension member, a shock absorber engine mounting, structural modifications to reduce body panel vibration and a new engine mounting to insulate high frequency engine vibration.

An analysis system for vehicle noise and vibration has been developed. It consists of minicomputer based analog processing system connected with a large main-frame computer. This system features multi-modes for data analysis, fast data processing, data compatibility with conventional analog systems and feasibility. Fast data processing was achieved by newly developed FFT processor and minicomputer software. A new remote control box makes it simple to operate. Data processed by the minicomputer can be transferred to a large mainframe computer for further analysis.

In a two-loudspeaker stereophonic reproduction system of a passenger car, the geometrical configuration of the right and left loudspeakers has the disadvantage of being asymmetrical to the listener. For this system, we have made both theoretical and experimental verifications of the effects of strongly reflected sounds on the sound pressure level difference and phase difference between two ears which determine the location of sound image in a small compartment of a passenger car. On the basis of these verifications, we have developed a new sound localization control system. With this system, acoustical effects such as sound expansion and ambience have been greatly improved in a passenger car. In this system, input signals to the loudspeakers are controlled so that the sound image produced by the loudspeaker nearer to the listeners may acoustically move so as to position itself symmetrically with the other loudspeaker with regard to the listeners.

On diesel vehicles, we frequently experience the phenomenon that low frequency fore and aft vibration of a vehicle, occurs at acceleration, does not decline in amplitude easily and rather increases finally. The phenomenon has recently attracted great concern in driveability problems on diesel vehicles. This phenomenon can not be explained well by the simple torsional vibration model of the powertrain with one node, which has been used so far successfully to analyze low frequency fore and aft vibration of a vehicle. So, we have assumed that the undamped vibration occurs through the interaction of the engine and the powertrain. Taking this interaction into consideration, we have constructed a simulation model, with which the undamped vibration can be simulated accurately. By this simulation model, we have estimated the order of magnitude of the effects of various design parameters affecting the undamped vibration.

Periodic regeneration of the diesel particulate trap is essential to maintain the collection efficiency and exhaust gas hack pressure at acceptable levels. The objectives of this study are to describe the phenomenology of ceramic foam filter regeneration process and to present its mathematical model. Further simulation study is carried out to estimate the effects of various factors including fuel additive on the ignition and the filter bed temperature and to investigate conditions of excessive temperature which could result in filter destruction. The model is based on the assumption that the regeneration process is composed of two steps. The first step is the additional heat supply from the external energy source, and the second step is the spontaneous combustion propagation. The results from the analytical model agreed very well with the experimental results.

The colour painting of polypropylene bumpers has required development of a new polypropylene surface treatment which provides improved adhesion of the paint film to polypropylene. According to the results of various improvement studies on the application of plasma treatment, it has been discovered that surface treatment by means of plasma of an oxygen and nitrogen gas mixture activated by microwave (2,450 MHz) provides a remarkable improvement in adhesion. Furthermore, establishing a technique to diffuse plasma effectively within the treatment chamber has enabled a uniform surface treatment of several polypropylene bumpers formed in large and complicated shapes.

A discomforting noise can sometimes be heard in a vehicle passenger compartment during acceleration which can be annoying to passengers. We call this noise a “rumbling noise”. A detailed study of the rumbling noise spectrum has clarified the generating mechanism of the rumbling noise and the relation between the spectral structure and the tone. In order to analyze the rumbling noise, we simulated it with electrically synthesized noise. This method showed that at the times when the noise is heard there are always more than three discrete harmonics which are half an order harmonics of the engine revolution. The sensation of discomfort depends on the phase, frequency and magnitude of each frequency component. To evaluate the noise quantitatively, we also analyzed the shape of the time domain noise envelope. The envelope shape has a good correlation with the feelings of discomfort.

In general, gear tooth surfaces of automobile transmissions are modified to reduce gear noise. This paper presents an analytical procedure for optimum surface modification, which is designed to supersede the experimental procedure by trial-and-error. First, gear noise level is shown by experiment to correspond with the scale of transmission error of a gear pair. Second, a computer program to calculate the transmission error is described. All factors of tooth surface modification and load condition can be fed to the program. For the test gear pair, the specific values of each factors to minimize transmission error, with due consideration of the tolerance determined by the production capacity, were determined and as a result a significant improvement in gear noise level was achieved. This new procedure can be used effectively for the design of quiet gears.

Recently engine sound quality is becoming more noticeable as noise level in a vehicle passenger compartment has been decreasing. It is necessary to reduce such discomforting noise as rumbling noise in order to improve engine sound quality. This paper describes the experimental study to find out causes of rumbling noise in an engine structure and several investigations to reduce rumbling noise. Some new approaches have been introduced to evaluate the influence of an combustion impact, the movement of a crankshaft, timing of rumbling noise and so on. The result shows that the primary cause of rumbling noise is the movement of a crankshaft due to the impact of combustion and next is the vibration characteristics of the engine-transmission assembly (power plant). Finally superior engine sound quality is achieved by increasing counterweights and stiffness of a crankshaft and also by optimizing the spark advance and improving vibration characteristics of various engine parts.

The characteristic of In-Cylinder gas motion of a multivalve engine is compared with a single intake valve engine, which have been predicted by a three-dimensional numerical simulation and flow visualization. The measured intake valve outlet velocity from helical and straight port was adopted as the boundary conditions. The computer graphics technique has been utilized to express the predicted numerical results as moving picture like visualized flow. This flow pattern was compared with the actual flow pattern visualized with metaldehyde as the tracer using the bottom viewed engine, which showed good agreement. The prediction for the multivalve engine showed that the swirl velocity is rapidly reduced by interaction between the flows from the two port, but the turbulence kinetic energy is similar to that in the engines with a single intake valve with helical port.

Eliminating brake squeal generated during brake application is an important task for the improvement of comfort in the vehicle. There has been a lot of research made on the problem of brake squeal in the past. And most of the papers presented elaborate on low frequency brake squeal (2-3kHz). However, brake squeal has often the high-frequency vibration. For this reason, we have made research into the high-frequency brake squeal (5-10kHz). Double-Pulsed Laser Holography is a useful method for visualizing small vibration of brake components during brake squeal generation. The results obtained using Holographic Interferometry show the rotaing disc vibrates in the bending mode with diametral nodes. Consequently, we think that the modification of brake disc can eliminate brake squeal, which is caused by self-excited vibration. Then we have calculated natural frequency and its vibration mode of a circular-plate added mass.