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Behavior of sprays formed by slit nozzle as well as swirl nozzles with the spray cone angle in the range of 40° ∼110 ° were studied in a constant volume N2 gas chamber. The fuels used are iso-pentane, n-heptane, benzene and gasoline. The ambient pressure and temperature were raised up to 1.0 MPa and 465 K, respectively. The injection pressure was mainly set at 8 MPa. Spray penetrates at an almost constant speed for a while after injection start and begins to decelerate at a certain point. This point was judged as breakup point, based on a momentum theory on spray motion, the observation of spray inside and the analysis of the spray front reacceleration which occurs under highly volatile condition.

As a result of recent improvements in engine efficiency, vehicle heating performance has decreased and the demand for auxiliary heat sources is increasing. To help meet this need, we have developed an auxiliary heat system known as the “Hot Gas Heater”. The Hot Gas Heater uses components common to the vehicle air-conditioning system that are not used during winter. However, there are some concerns with this system. In this paper we describe our solutions to these problems. We reduced gas flow noise through multi-stage pressure reduction, and prevented fogging by adding “water retention memory” and “evaporator outlet air temperature control” functions to the system. As a further benefit, we developed a New Accumulator Cycle that moves the cooling cycle accumulator tank to the high-pressure side.

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 applying soap film geometry to an automobile body structure has been developed. Its curved surface reduce both interior noise and damping material application because of its high rigidity and uneven deformation mode. This paper demonstrates these mechanism, benchmarks their performance with conventional flat and bead panels and presents an application to the floor panel of an automobile body.

This paper describes a new method for objective evaluation of wind noise in the passenger compartment of a car. The loudness and direction of noise in each frequency band can be estimated by performing analyses based on human hearing properties. Therefore, those wind noise components that are annoying to the passengers or those wind noise components whose source location can be determined by the human listener can be identified objectively. Furthermore, the total loudness of wind noise can be estimated quite precisely by adding the loudness of the frequency bands for noise emanating from the direction of the side window.

This paper describes methods to attain a low cost tire pneumatic pressure monitor. We already established two kinds of algorithms for indirect detection of under-inflated tires without requiring any air pressure sensors. One method is to use a disturbance observer and the least mean square method. The other method is to compare the loaded radii of the tires. We have developed an algorithm that reduces the number of calculations needed, while maintaining a relatively small program size, and realized a tire pneumatic pressure monitor that does not require any hardware cost, by incorporating it into the program for the antilock brake system (ABS).

An investigation was conducted into pressure pulsation in the exhaust port, which greatly affects volumetric efficiency and engine performance. From experiments using a single blow-down generator, it was established that the amplitude of the pressure pulsation increases as the manifold branch is lengthened and that large negative pressure synchronized with the timing of valve overlap can be obtained if a proper branch length is used. The performance of a 2ℓ test engine was optimized by varying the length of both the manifold branches and front pipe forks. It was found that whereas front pipe fork length affects engine performance over only a narrow range of engine speed, optimizing manifold branch length results in a considerable improvement over a wide engine speed range. In the course of optimizing the exhaust pipe manifold length of this two-degree-of-freedom exhaust system, abnormal exhaust noises were emitted at specific engine speeds during deceleration.

Whinning gear noise(final gear noise), one of the causes for automobile interior noise is due to the exciting force of final gear kit and as a general countermeasure for this problem, a reduction of resonance level in transfer system and better meshing of gears have been utilized. However,vibration characteristics of final gear unit have not been considered much in this case. Authors have executed impacting test on final gear unit and confirmed its vibration characteristics. Based on this fact,vibration model consisting of bearings and gears spring system was constructed to evaluate vibration characteristics of final gear unit along with the results obtained from final gear unit of front engine,rear drive passenger car.

It is well known that pilot injection is an effective method of reducing diesel knock noise during idling, but no actual system has as yet been commercially produced. With the objective of developing a practicable pilot injection device, simulations were conducted of various simple mechanisms in order to determine the best specifications and analyze the fuel injection characteristics. Based on these results, a chamber expansion type pilot injection device, which enables the injection pump pressure chamber volume to be increased at a given moment during the fuel compression stroke, has been developed and has been found to remarkably decrease knock noise during cold idling. An investigation into the effects of this device on output power, exhaust emissions, cold startability and durability revealed that it is eminently suitable for practical application.

To analyze chain noise which occurs in transfers using silent chain, analysis considering the energy of the noise source is effective. We can simulate chain noise by calculating a dimensionless coefficient of “chain noise energy” consisting of two contributing factors: the energy of the collision when the chain meshes with the sprocket, and fluctuation in the chain speed.