Land vehicles – Wheeled – Attachment
Reexamination Certificate
2000-02-08
2001-07-03
Culbreth, Eric (Department: 3611)
Land vehicles
Wheeled
Attachment
C701S045000
Reexamination Certificate
active
06254126
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The invention relates to a device and a method for detecting a weight of an object and/or an occupant on a vehicle seat.
Occupant protection systems in motor vehicles according to the prior art have, in addition to an impact detecting device have an occupant position detecting device and a weight detecting device for occupants or objects on the vehicle seat. Information about the position and weight of the occupant or, for example, a child seat, is intended to achieve the measured inflation of associated air bags which is matched to the occupant.
A known device for weight detection for a motor vehicle (see Published, Non-Prosecuted German Patent Application DE 42 37 072 A1) contains a sheet pressure sensor in the form of a mat, whose electrical resistance decreases with increasing pressure on a surface of the sheet. The mat is incorporated into the seat upholstery surface of the seat.
SUMMARY OF THE INVENTION
It is accordingly an object of the invention to provide a device and a method for detecting the weight of an object and/or an occupant on a vehicle seat that overcome the above-mentioned disadvantages of the prior art methods and devices of this general, which has simple construction.
With the foregoing and other objects in view there is provided, in accordance with the invention, a device for detecting a weight of an object, including a vehicle seat for receiving the objected to be weighed; a controllable electric motor for adjusting the vehicle seat; a sensor for registering a measured variable dependent on a force supplied by the controllable electric motor; and a control and evaluation circuit deriving a weight signal from the measured variable registered during a controlled adjustment of the vehicle seat.
According to the invention, the force output in order to adjust the vehicle seat by an electric motor provided for the seat adjustment is a measure of the weight force—weight in the following text—moved by the electric motor. In this case, the weight moved is composed of the weight of the vehicle seat, the frictional force to be overcome and the weight of an occupant on the vehicle seat or of an object disposed on the vehicle seat. In order to determine the force output by the electric motor, the sensor is provided which registers a measured variable that depends on the force supplied by the electric motor and therefore on the weight moved by the electric motor. The control and evaluation circuit subsequently derives the weight signal from the measured variable registered during the controlled adjustment of the vehicle seat.
The measured variable registered is preferably a current consumed by the electric motor, a rotational speed of the electric motor or a torque of the electric motor.
For the purpose of the controlled adjustment of the electric motor, the control and evaluation circuit controls the electric motor with the effect that the electric motor is set moving. It is not necessary for the position of the vehicle seat also to be adjusted in a manner that is noticeable to the occupant. The electric motor should preferably be operated beyond its starting current phase, in order to be able to register the respective measured variable in the steady state, the transient phase of the measured variable as the electric motor is switched on or off not being taken into account by the control and evaluation circuit when the measured variable is evaluated. About five revolutions of the electric motor are sufficient for this purpose. During the controlled adjustment of the vehicle seat in this way, the current drawn by the electric motor is preferably registered and evaluated by the control and evaluation circuit.
It is preferable for the device for detecting the weight to make use of an electric motor for adjusting the height of the seat. Alternatively, however, an electric motor for adjusting the seat longitudinally can also be used. In any case, the electric motor must adjust the vehicle seat against the weight of the occupant.
In order to detect the weight, use is preferably made of electric motors that are already disposed in a vehicle seat for adjusting the seat position. In this case, apart from the sensor for registering the current and the control and evaluation circuit, no additional components are needed for detecting the weight. In particular, no sensor that has a large area and is associated with some intervention in the vehicle seat structure is needed. The current sensor and the control and evaluation circuit can simply be connected to the electric motor in or on the vehicle seat, since in the case of an electrically adjustable vehicle seat, mechanical and electrical interfaces for the electric motor are already provided in or on the vehicle seat. Furthermore, the drive electronics that already exist for adjusting the vehicle seat can simply be expanded, in software or hardware terms, by the control and evaluation circuit of the weight detecting device.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in a device and a method for detecting the weight of an object and/or an occupant on a vehicle seat, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.
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“Weight Sensing for Occupant Restraint System Utilizing Load Cell Technologies”, XP-00726567.
Bauer Hans-Peter
Danz Gerhard
Frisch Markus
Heitzer Günter
Kippelt Ulrich
Culbreth Eric
Greenberg Laurence A.
Lerner Herbert L.
Lum L.
Siemens Aktiengesellscaft
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