Passenger Car Model Research Articles

Application of Hybrid Frequency Domain Substructuring for Modelling an Automotive Engine Suspension

A practical application of hybrid FRF-coupling (Frequency Response Function) in the development of a passenger car is presented. First, a short review is given about FRF-coupling in general. Next, some problems are discussed which may be encountered when both analytical and experimental FRF-data is used in FRF-coupling. This is also known as hybrid modelling. The main part of this paper presents a successful application of hybrid FRF-coupling to analyze and solve an interior noise problem of a passenger car. Both analytical and experimental FRFs were used to create a hybrid dynamic model of a complete passenger car. The engine and its suspension system were modelled using finite elements, while the remainder of the car was modelled by experimentaly derived FRFs. This hybrid model was then used to compute the response of the vehicle due to the engine excitation. Measured noise transfer function were used next to compute the interior sound pressure level using forced response results of the hybrid car model. Subsequently, the hybrid model was used to analyze the problem, and to predict the effects of an alternative design of the engine suspension on interior noise. Numerical results indicated that the alternative design would have a significant positive effect on noise. This was confirmed by verification measurements on a car.

A114 乗用車モデル後流の非定常圧力計測

Unsteady and multi-point pressure measurements have been performed to the wake behind a passenger-car model. Mean pressure measurements of the wake using multi-hole pitot tubes have been reported. Unsteady measurement of the wake, however, has not been reported yet The model which was used in this experiment was a sedan type and 1/5 scale. The passenger-car model was put in a wind tunnel with a moving belt, which moved the same speed as the uniform flow of the wind tunnel. We measured pressure at points of a plane behind the model and perpendicular to the uniform flow. The number of the points measuring the pressure was 256. The obtained results were animated and the fluctuation of the wake was visualized. The results under the conditions that the moving belt was turned on and off, was discussed.

Octane Number Requirement Survey of 1995 Japanese Model Passenger Cars.

Octane Number Requirement Survey of 1995 Japanese Model Passenger Cars.

New Concept of Automatic Control for a Passenger Car Clutch

This paper highlights the main functions of clutch automatic control systems. These are: forced clutch disengagement during gear shifting and when the engine falls below its minimum operating speed; forced clutch engagement under conditions of increasing engine speed or vehicle speed at a preset level or at a definite throttle position; adjustment of clutch friction torque, depending on the control parameter used. To achieve this, a closed-loop automatic control system is required. The system compares control signals with feedback from a selected parameter and generates commands for changing clutch friction torque. At present some automatic clutch systems use either the position of the accelerator pedal (‘Drivematic’ and ‘Guidosimplex’) or engine speed (ACTS) as the control parameter. The feedback parameter in these systems is the position of the clutch drive element. Comparison of the two systems shows that those using engine speed as the control parameter are more advanced, although their design is more complex. Engine speed is also used in the system of automatic electrovacuum friction clutch control (EPS) designed at the Central Automobile and Automobile Engine Scientific Research Institute (NAMI), but the principle of operation is totally different from existing systems. Particular features of this system are as follows: all necessary modes of automatic control are provided by only one multi-function electromagnet acting on the vacuum valve in the clutch actuating servo chamber; the feedback is dependent on the position of the clutch actuator and is provided by a spring acting on the armature of the valve drive electromagnet—the force of this spring changes in proportion to the position of the clutch actuator; clutch friction torque control as a function of engine speed is provided by changing the current strength in the electromagnetic winding—these changes are initiated by the electronic control unit of the automatic control system. To achieve the optimal performance of modern high-speed engines in combination with an automatic clutch system, all elements of the clutch control system must have minimal delay in converting input signals into control signals. This requirement resulted from an investigation of the EPS mathematical model comprising three non-periodic dynamic elements. The same results were experimentally proved when amplitude and phase frequency characteristics of the control system were measured. It was shown in particular that the time constants of dynamic elements must not exceed 0.04–0.06 s. This required the application of a brand new engineering circuit for designing the EPS electronic unit. The EPS system is now in mass production and is standard equipment for some models of small passenger cars manufactured in the former Soviet Union. The system has been patented in the United States, Japan, Germany, Great Britain, France and Italy.

Development of a plastic intake manifold

Plastic intake manifolds have already been installed in many models of European passenger cars. They are produced using a melt core molding technique with a low melting point alloy. We are the first company in the world to develop this new production technique which is a combination of blow and injection molding. Subaru employed this new plastic intake manifold on super-charged 0.66-litre engines of the Sambar Dias for the domestic market in 1992. This paper shows the story of the development and the features of this new technology.

The Effect of Bandwidth of Semiactive Dampers on Vehicle Ride

A passenger car model with a full car body and four wheel-axle assemblies is used to investigate the influence of semiactive suspensions on ride performance. Mean square values are evaluated for various damping levels and control valve switching times. Due to severe nonlinearities, frequency responses are not obtained directly. They are reconstructed from Fast Fourier Transform (FFT) using a Hanning window. The results are compared with those from LQR active suspensions and pure on-off dampers. The effect of control valve switching time (bandwidth) is studied and shows a significant influence on the vehicle ride, suspension travels, and tire deflections.

SYMBOLIC QUASI-STATIC AND DYNAMIC ANALYSES OF COMPLEX AUTOMOBILE MODELS

SUMMARY This paper describes how quasi-static and dynamics analysis methods are combined to simulate of a “full-scale” passenger car model. It also describes a novel method for combining symbolic and numerical equation formulations to generate quasi-static analysis algorithms. A quasi-static model is first used to simulate three-dimensional suspension kinematics and compliance properties. The results from this analysis are then used to fit coefficients to polynomials that describe the suspension motions. These coefficients are then employed in a dynamics model that is formulated using the same polynomial equations. The method is illustrated for an automotive vehicle model, using a suspension representation with 11 degrees of freedom (DOF), and a full-vehicle model with 14 DOF. The symbolic multibody program AUTOSIM is used to derive the equations and optimize them for computer solution. The overall simulation is sufficiently detailed to captures the influences of bushing compliances, and yet is computationally efficient to the extent that it runs in real-time in a driving simulator.

A212 ムービングベルト付風洞を用いた自動車模型回りの5孔ピトー管サーベイ

The cross flow vector, total pressure loss and microdrag maps around 1/5 scale passenger car models are visualized by flow surveys with 5-hole pitot tubes in a scale wind tunnel with a moving belt. Five passenger car shapes, that is, a notch-back, a sedan, a sedan with under floor cover, a first-back, and a wagon are examined and survey data are obtained in the cross sections in the wake, under the floor, and beside the car. These data are calculated and presented as color contour maps with the car shapes from CAD data. The survey around the car clarifies the effect of the belt movement, and that the microdrag map in the near wake can indicate the part of the body shape which produces the large portion of the drag.

Interior idle noise in current model passenger cars

The author, a consultant in architectural acoustics, became interesting in the vast differences in interior noise levels between passenger cars in today's market. Octave‐band noise levels were measured in 20 different automobile models. In order to reduce the number of variables, the measurements were limited to the driver's position with the car stopped and engine at idle. In the 31‐Hz band, noise levels varied 20 dB between two different models by the same manufacturer. The range of A‐weighted levels spanned only 8 dB. While the A‐weighted sound levels as published by most consumer magazines provide some indication of relative loudness, examination of octave‐band levels shows radical differences between models. Some observations and conclusions are drawn by an “enlightened” consumer.

Survey of the exterior noise of some passenger cars

The results of extensive measurements made on 58 different models of European passenger cars are used to show the influence of speed and driving conditions on noise emission. The range of levels covered by different driving conditions around a speed of 50 km/h has median values of 66·4 to 79·5 dB(A). The spread in levels measured for all car models in any single driving condition is smaller than the spread due to different driving conditions.

Performance of Exhaust Control Devices on 1966 Model Passenger Cars

Road tests have been carried out in five different cities with a fleet of 300 passenger cars consisting of three different makes, half of which are equipped with the 1966 exhaust control devices required by the state of California. The performance of these devices during the first series of tests has been evaluated. All three makes of device-equipped cars produced significantly lower emissions of hydrocarbons and carbon monoxide than did similar cars tested in 1962 and 1963. There were no consistent differences among the three makes of cars with respect to carbon monoxide and hydrocarbon emissions.

Results of Octane Number Requirement Survey on Japanese 1964 and 1965 Model Passenger Cars

Results of Octane Number Requirement Survey on Japanese 1964 and 1965 Model Passenger Cars