Motor vehicles – Surface effect vehicles – Dynamic seal or fluid curtain
Patent
1991-03-19
1994-03-08
Mitchell, David M.
Motor vehicles
Surface effect vehicles
Dynamic seal or fluid curtain
180141, B62D 506
Patent
active
052919625
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a power steering device for use in motor vehicles in general and more particularly to a power steering device which undergoes a speed sensory control and a responsiveness control.
2. Description of the Related Art
A popular power steering device for use in motor vehicles is a speed sensing type. However, a motor vehicle provided with a power steering device which undergoes a responsiveness control is now demanded in view of the desired drivability and stability.
Further, in order to enhance drivability and stability of motor vehicles, it is necessary to investigate performance from two aspects because motor vehicle performance changes in response to steering operations of drivers, and in response to disturbances such as road irregularity and gusts of wind.
For the former aspect, one must consider increased motor vehicle speeding and the advanced ages of motor vehicle drivers which causes an expansion of in the range of physiological ability levels in relation to driving skill. It is therefore necessary to alleviate problems caused by the increased speeding and the expansion in the range of physiological ability levels within the motor vehicle side, i.e., the former aspect.
For example, an expressway in the middle of the night is as if it were a huge conveyer belt filled with trucks. These trucks are driving towards the metropolitan area. The distance between these truck groups is generally short and the speed thereof is high. Further, highway buses between cities aer present. Because of their advantages such as inexpensive fairs and ease of use, living space outside the city with a high quality, and attentive services, not only are day time highway bus services increasing, but also night time bus services are increasing. Night bus services were understood at the beginning to be used only to supplement railway train services. This is no longer true. As such, on one hand, high speed and long distance services are active. However on the other hand, in particular, with regard to trucks, the shortage of truck drivers is serious, and in addition, the age of the drivers has been increasing. Further, there appears to be an indication of woman driver expansion. The higher the speed of the motor vehicle is, the more the response performance thereof reduces. Still further, physiological abilities relating to driving skill of advanced age drivers and woman drivers are relatively low in comparison with those of young man (see FIG. 1). A system is desired which realizes a compensation in the motor vehicle for the decrease of response performance at high speeds and the physiological ability difference of the drivers. Moreover, a large sized motor vehicle, which requires a relatively wide space on the running road in comparison with a passenger car, should be provided with a better response performance than the passenger car.
Further, with regard to the desirable motor vehicle response characteristics, there are reports, one of which defines T.beta., a factor corresponding to the product of a time constant and yaw gain. The report indicates that the smaller the products is, the higher the subjective judgement of the driver is (see FIGS. 2a through 2c). Another report indicates that there is an optimum region of moving direction holding property in a range of small time constants and of certain amounts of yaw acceleration again (see FIG. 3). These data are concerned with passenger cars. However, these tendencies are similar in trucks and buses. FIG. 4 shows an example of the response characteristic of a truck and a bus, wherein the truck is equipped with a front engine and a leaf suspension and the bus with a rear engine and an air suspension. The gain and the phase lag of the truck are smaller than those of the bus. Further, the subjective judgement of the truck driver is better than the bus driver. The gain and phase lag increase in response to an increase in the vehicle speed (see FIG. 5) and thereby burdens to drivers increase corre
REFERENCES:
patent: 4332303 (1982-06-01), de Maight
patent: 4703819 (1987-11-01), Hosotani
Momiyama Fujio
Tokuda Noriaki
Hino Jidosha Kogyo Kabushiki Kaisha
Hurley Kevin
Mitchell David M.
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