Data processing: measuring – calibrating – or testing – Measurement system – Pressure
Reexamination Certificate
2000-03-23
2002-10-29
Wachsman, Hal (Department: 2857)
Data processing: measuring, calibrating, or testing
Measurement system
Pressure
C702S140000, C701S094000
Reexamination Certificate
active
06473712
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a device and a method for determining a roadway gradient quantity.
BACKGROUND OF THE INVENTION
Conventional gradient sensors have different designs and different modes of operation. For example, U.S. Pat. Nos. 4,779,353, 5,428,902, and German Patent No. DE 40 25 184 describe gradient sensors having a sensor body which is filled with a measuring liquid whose liquid level aligns in response to an inclination. From the position of the liquid level, it is then possible to determine the inclination of a motor vehicle. The position of the liquid level is ascertained either on the basis of a change in resistance or a change in capacitance. Both the change in resistance and the change in capacitance are produced by the change in position of the liquid level of the measuring liquid and the associated different wetting of electrodes which are located in the sensor body.
Gradient sensors of the kind described above have the disadvantage of a complex design, resulting in their susceptibility to faults. This can lead to an increased risk of failure, therefore they are not possible for permanent use in a motor vehicle.
Other conventional sensors operate in accordance with the principle that an acceleration acting upon the sensor is converted into a change in pressure which is used as a measure for the acceleration acting upon the sensor. U.S. Pat. No. 3,046,793 describes an acceleration sensor having a cylindrical sensor body which is filled with a measuring liquid. The measuring liquid is used for damping the moving parts of the acceleration sensor and for converting an acceleration into a pressure. This pressure is measured and the acceleration is determined from the change in pressure. U.S. Pat. No. 5,291,784 describes an acceleration sensor having a cylindrical sensor body which is divided into two measuring chambers by a membrane. The measuring chambers are filled with a measuring liquid. An acceleration results in a pressure difference between the two measuring chambers. This pressure difference is measured, and the acceleration is determined therefrom.
The two aforementioned types of acceleration sensors are not suitable for determining the roadway gradient of a motor vehicle. They measure a pressure which develops because an acceleration acts upon the measuring liquid in the sensors. Since they contain moving parts, they are susceptible to faults.
Additionally, liquid level indicators which are used in vehicles. European Patent No. EP 0 303 874 describes a device for ascertaining the liquid quantity in a fuel tank which is mounted in a vehicle. The device includes three level sensors which are arranged in a predetermined position relative to each other. On the basis of the measured values of the three level sensors, a value for the filling amount of the tank, and a value for the inclination of the tank, and, consequently, also of the vehicle is calculated. When ascertaining the filling amount, the inclination of the tank is taken into account. Therefore, the ascertained filling amount is independent of either the inclination of the tank or of the vehicle.
German Patent No. DE 197 04 683 describes a device for measuring the inclination of a container relative to a liquid level inside the tank. In the case of a rigid installation of the container in the vehicle, it is possible to infer the vehicle inclination and the vehicle acceleration. According to an exemplary embodiment, three sensors are used for ascertaining the inclination of the container or of the vehicle. An inclination of the container results in different liquid levels; consequently, the sensors give out different voltages accordingly. On the basis of the different voltages and the known geometric arrangement of the liquid level sensors, a gradient signal is determined with the assistance of an evaluation circuit.
Using the two last-mentioned devices, it is possible to ascertain the inclination of the liquid container, and, consequently, also that of the vehicle. The gradient of the roadway on which the vehicle stands or moves, in the following also called roadway gradient or slope gradient, cannot be ascertained by any of the two aforementioned devices for the following reason: if one wishes to ascertain the roadway gradient on the basis of the inclination of the liquid container, then the motion of the vehicle must also be considered in doing so. The inclination of the vehicle is substantially composed of two components. One component originates from the gradient of the roadway. The other component results from the motion of the vehicle, as exists, for example, during acceleration or deceleration (pitching) or during a steering maneuver (rolling motion). Since, within the framework of determining the vehicle inclination when working with the two devices appertaining to the related art, no quantities are available which describe the aforementioned vehicle movement, the roadway gradient cannot be ascertained with the assistance of these devices, because the vehicle movement cannot be eliminated from the vehicle inclination.
Even if the two devices were modified to the effect that, by using them, it would be possible to ascertain the gradient of the roadway, they still have the disadvantage that they use liquid level indicators which contain moving parts, and therefore are susceptible to faults. Secondly, they require a non-negligible volume of liquid which is consequently lost from the tank capacity.
SUMMARY
An object of the present invention is to provide a device for determining a roadway gradient quantity which has a rugged design, and which is reliable, i.e., little susceptibility to faults. Moreover, the measuring arrangement used should not require a lot of mounting volume.
In the case of a liquid container rigidly joined to the vehicle, the inclination of the liquid container corresponds to the inclination of the vehicle, or to the inclination of the liquid contained in the liquid container.
The device according to the present invention for determining a roadway gradient quantity, which describes the gradient of a roadway on which a vehicle is situated, includes a liquid container which is mounted to the vehicle and contains a liquid. In one advantageous embodiment, this liquid container is a fuel tank.
With regard to a rugged and reliable design of the device, an advantageous embodiment is the use of pressure sensors as a measuring arrangement. In this embodiment, at least one pressure sensor is mounted in the area of the bottom of the liquid container. Using this pressure sensor, a pressure quantity is ascertained which describes the hydrostatic pressure in the liquid container. The pressure sensor is in communication with an evaluation unit. In the evaluation unit, the roadway gradient quantity is determined as a function of the pressure quantity.
The roadway gradient quantity describes the roadway gradient along and/or transverse to the vehicle's direction of travel.
In accordance with conventional physical principles, the evaluation unit determines the liquid level in the liquid container from the hydrostatic pressure and the inclination of the liquid container from the change in the liquid level, the inclination of the liquid container corresponding to the inclination of the vehicle. The roadway gradient quantity or slope gradient of the roadway surface is then determined from the inclination of the vehicle, taking into account vehicle movement. Herein the phrases “roadway gradient quantity” and “slope gradient of the roadway” are used interchangeably, and the phrases mean either a slope gradient of the roadway in the direction of travel of a vehicle or a slope gradient of the roadway transverse to the direction of travel of a vehicle or a combined vector of the slope gradient of the roadway both in the direction of travel and transverse to the direction of travel. The slope gradient is important information for recognizing the motor vehicle condition and for controlling specific motor vehicle functions. The slope gradient information is of signifi
Faye Ian
Leimbach Klaus-Dieter
Kenyon & Kenyon
Kim Paul L
Wachsman Hal
LandOfFree
Device for determining a roadway gradient quantity does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Device for determining a roadway gradient quantity, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Device for determining a roadway gradient quantity will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2976953