Electricity: motive power systems – Automatic and/or with time-delay means – Moisture content or wetness
Reexamination Certificate
1999-12-14
2001-02-06
Masih, Karen (Department: 2837)
Electricity: motive power systems
Automatic and/or with time-delay means
Moisture content or wetness
C318S443000, C318S444000, C150S163000
Reexamination Certificate
active
06184642
ABSTRACT:
The present invention relates to the technical field of vehicle wiper devices, and more particularly relates to a system and a method for controlling the operation of a vehicle window wiper device, the said device comprising:
an electric drive motor connected to at least one wiper blade arm and adapted to impart to the arm an oscillating movement; and
a wiper blade for the window coupled to the said at least one wiper blade arm, the control system (method) being adapted to control the operation of the wiper blade arm in a variable manner in dependence on the quantity of liquid present on the window.
It is known in the art automatically to control the operation of a wiper device (hereinafter more briefly wipers) in dependence on the presence of liquid and/or the quantity of liquid present on a window of a vehicle (for example the windscreen or rear window), the generic term “liquid” in this context indicating both rain or other types of hydrometeors and liquid detergent.
Rain sensors able to detect the presence of even a few drops on the window are, for example, formed by utilising optical components in combination with photo-detector devices or, in the most simple cases, are constituted by electrically conductive components the electrical resistance of which varies as a function of the rain present on the component.
Such sensors are disposed close to the window under control, and the information which they detect is provided to the input of the devices driving the wiper or wipers for activating/disactivating it/them or modifying it/their manner of operation.
A disadvantage of known arrangements is that of requiring the installation of specific components, which is onerous in itself, and therefore, in the last analysis, affects the sale price of the vehicle, making it possible to adopt such a device only for high prestige vehicles.
The arrangement of the sensor on the window must moreover be designed with care since the sensor must not reduce the transparency of the window, whilst simultaneously guaranteeing an accurate detection. The performance of the system is in fact related to the correct positioning of the sensor since there must be a correspondence between the real condition of the window and that detected by the sensor in the specific zone of the window placed under direct observation.
The object of the invention is that of overcoming the above-explained disadvantages by providing an innovative control system for the operation of a wiper device which does not need the installation of a specific rain sensor, but detects the presence and/or, indicatively, the quantity of rain indirectly through the operation of the wiper itself.
To this end the subject of the invention is a system for controlling the operation of a vehicle window wiper device characterised in that it comprises:
first sensor means for detecting a first quantity dependent on the instantaneous friction between the said wiper blade and the vehicle window, adapted to provide a first output signal corresponding to this first quantity;
second sensor means for detecting a second quantity correlated to the aerodynamic load acting on the said wiper blade, adapted to provide a second output signal corresponding to this second quantity; and
a processing and control unit coupled to the said first and second sensor means for receiving the said first and second signal at its input, and arranged to:
determine a value of a third quantity correlated to the quantity of liquid present on the window on the basis of the received signals and by comparison with a predetermined reference model; and
provide output control signals for controlling the activation of the electric motor in a predetermined manner as a function of the determined value of the said third quantity.
The present invention also provides a method for controlling the operation of a vehicle wiper device characterised in that it comprises the operations of:
detecting a first quantity dependent on the instantaneous friction between the said wiper blade and the vehicle window;
detecting a second quantity correlated to the aerodynamic load acting on the said wiper blade;
determining the value of a third quantity correlated to the quantity of liquid present on the window on the basis of the said first and second detected quantity and by comparison with a predetermined reference model; and
controlling the activation of the electric motor in a predetermined manner in dependence on the determined value of the said third quantity.
The operation of the control system forming the subject of the invention is based on the detection of the instantaneous friction between the wiper blade and the vehicle window. In a simple physical model this quantity is a function of the quantity of liquid present on the vehicle window and the aerodynamic load acting on the wiper blade, the term aerodynamic load meaning the aggregate of the contributions to the lift which is generated as a consequence of the motion of the vehicle and the pressure due to the opposing wind. According to the model, in each aerodynamic load condition the greater the quantity of rain or liquid detergent present on the window the lower the friction encountered by the wiper blade in the action of wiping over the surface of the window.
The friction between the wiper blade and the window can be detected qualitatively by measuring a quantity dependent on it and which is more easily accessible for measurement, such as, for example, the current consumed by the electric motor or the resistant torque applied to the motor itself.
The contribution of the aerodynamic load acting on the wiper blade can be estimated by detecting a quantity correlated to it such as the instantaneous pressure of the air in the region of the wiper blade or, more simply, the speed of the vehicle.
Once in possession of information relating to the instantaneous friction and the aerodynamic load it is possible to estimate the presumable quantity of liquid present on the window by comparison with a mathematical reference model previously obtained by experimental means, and stored in the form of a matrix of data.
In dependence on the quantity of liquid on the window deduced indirectly, and in particular on its variation over time, the system finally controls the operation of the wiper arm or arms by modifying operating parameters thereof such as the repetition frequency of the oscillations or possibly the duration of these as will be described in more detail hereinafter.
REFERENCES:
patent: 4499410 (1985-02-01), Iacoponi et al.
patent: 4588935 (1986-05-01), Kaneiwa et al.
patent: 4922570 (1990-05-01), Hiroshima et al.
patent: 5119002 (1992-06-01), Kato et al.
patent: 5561882 (1996-10-01), Hirohama et al.
patent: 43 30 112 (1995-03-01), None
patent: WO 98/29285 (1998-07-01), None
Denjo Manufacturing Italia S.P.A.
Masih Karen
Sughrue Mion Zinn Macpeak & Seas, PLLC
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