Measuring and testing – Liquid level or depth gauge – Float
Reexamination Certificate
1998-12-09
2001-01-23
Patel, Harshad (Department: 2855)
Measuring and testing
Liquid level or depth gauge
Float
C073S315000
Reexamination Certificate
active
06176134
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a filling level sensor for generating electrical signals as a function of a filling level of a fluid in a container, said sensor having a bracket which is pivotably mounted on a carrier part and which can be deflected by a float for the purpose of moving an actuator of a regulator which is designed to generate the electrical signals.
BACKGROUND OF THE INVENTION
In motor vehicles today such filling level sensors are used, for example, to determine a filling level of fuel in a fuel container, and are known from practice. Here, the mounting arm is fabricated in two parts with a bracket fabricated from plastic and a lever wire for holding a float. The regulator is designed, for example, as a potentiometer with a sliding track which is arranged on the carrier part, or as a magnetically active position sensor having a resistor network which is arranged on the carrier part. The actuator of the regulator is usually attached to the bracket and, depending on the shape of the regulator, either has a sliding contact or a magnet. In order to ensure a constant prestress of the actuator or a constant distance between the actuator and the regulator components arranged on the carrier part, the mounting arm has two axial guides. As a result, forces transmitted from the float to the mounting arm are supported by the axial guides.
A disadvantage with the known filling level sensor is that it is of structurally very complex design as a result of the axial guides. In addition, because of the tolerances of the guides and of the mounting arm, in the known filling level sensor, the prestress of the actuator or the distance of the actuator can be kept constant only inadequately. As a result of forces acting on the mounting arm via the float, the mounting arm can tilt between the two guides so that the prestress of the actuator or the distance between the actuator and the components arranged on the carrier part is also changed.
SUMMARY OF THE INVENTION
The invention is based on the problem of designing a filling level sensor of the type mentioned at the beginning in such a way that it is constructed in a particularly simple way and prevents as reliably as possible a change in the prestress of the actuator or the distance between the actuator and the regulator components which are arranged on the carrier part.
This problem is solved according to the invention by virtue of the fact that the actuator is arranged in a guide of the carrier part.
By virtue of this design, the mounting arm does not require any complex guide on the carrier part. As a result, the filling level sensor according to the invention is constructed in a particularly simple way. The bracket and the carrier part can therefore be fabricated very easily, for example from plastic using the plastic injection molding method. The guide of the actuator may additionally be made significantly smaller, and therefore also lower in friction than the guides for the mounting arm. Furthermore, thanks to the invention, tilting movements of the mounting arm no longer lead to a change in the prestress of the actuator or in the distance between the actuator and the regulator components arranged on the carrier part. Therefore, the mounting arm may be guided by the carrier part in a very loose way.
The actuator could, for example, be moved by a magnet arranged on the mounting arm. However, arranging a coupling element between the mounting arm and the actuator helps to reduce the costs of the filling level sensor according to the invention.
According to another advantageous development of the invention, vibrations are not transmitted to the actuator of the regulator if the coupling element has a damping element. Furthermore, forces transmitted from the mounting arm to the coupling element do not lead to tilting of the actuator in the guide.
The filling level sensor according to the invention can be mounted particularly easily if the coupling element is arranged perpendicular to the direction of movement of the actuator and is designed so as to be capable of sliding into itself telescopically.
The actuator follows a change in the mounting arm virtually without delay and can additionally be mounted very easily if the coupling element has a latching connection for attachment to a lever wire which has a round cross section and supports the float.
The filling level sensor according to the invention is of particularly cost-effective design if the actuator is arranged on a mounting part which is displaceable in the guide of the carrier part. As a result, the mounting part may be fabricated, for example, from plastic using the plastic injection molding method while the actuator, which usually has to be manufactured in a complex fashion, has a particularly small dimension.
According to another advantageous development of the invention, tilting of the actuator or of the mounting part in the guide of the carrier part is reliably avoided if the coupling element is mounted on the mounting part so as to be capable of pivoting about an axis which is arranged transversely with respect to the direction of movement of the actuator.
A further contribution to reducing the fabrication costs of the filling level sensor according to the invention is made if the mounting part has laterally protruding bolts which penetrate the guide of the carrier part and have a round cross section. In this context, the mounting part may be fabricated in one piece with the coupling element and pivot in the guide when the mounting arm moves away.
The filling level sensor according to the invention may have very large tolerances without the actuator or the mounting part tilting in the guide if the coupling element has a ball joint for attachment to the mounting arm and/or to the mounting part. As a result of this design it is, for example, no longer necessary for the guide on the carrier part for the actuator to be designed to correspond to the pivot radius of the mounting arm. As a result, the regulator can, for example, also have a straight sliding track or be mounted obliquely on the carrier part.
REFERENCES:
patent: 4671121 (1987-06-01), Schieler
patent: 4924704 (1990-05-01), Gaston
patent: 5140303 (1992-08-01), Meyer
patent: 5333499 (1994-08-01), Gaston
patent: 5341679 (1994-08-01), Walkowski et al.
patent: 4438332 (1996-05-01), None
patent: 4300383 (1996-07-01), None
Mannesmann VDO AG
Mayer Brown & Platt
Patel Harshad
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