Measuring and testing – Liquid level or depth gauge – Float
Reexamination Certificate
2000-05-08
2001-07-31
Larkin, Daniel S. (Department: 2856)
Measuring and testing
Liquid level or depth gauge
Float
C073S305000, C073S314000, C073S29000R, C340S625000
Reexamination Certificate
active
06267007
ABSTRACT:
BACKGROUND 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, having a bracket which is mounted on a carrier part in a pivotable and axially nondisplaceable fashion and which activates a regulator as a function of its adjustment angle, having a lever wire attached to the bracket and fitted with a float, and having an axial guide arranged at a distance from the pivot axis of the bracket.
Such filling level sensors are used in current motor vehicles, for example, for determining a filling level of fuel in a fuel container, and are known from practice. Here, the bracket has, as an axial guide, a hook for engaging behind a carrier part collar which is arranged at a distance from the bearing. Forces which are transmitted from the float to the lever wire and thus to the bracket are, as a result, supported in the region of the pivot axis and of the axial guide. The regulator is designed as a potentiometer with a slideway arranged on the carrier part and a sliding contact which is attached to the bracket and is prestressed against the slideway. The axial guidance of the bracket ensures that a constant distance is maintained between the bracket and the carrier part, and thus that there is an envisaged degree of prestress of the sliding contact against the slideway.
A disadvantage with the known filling level sensor is that as a result of the hook for the axial guidance the bracket is designed as a component which is difficult to produce using injection molding technology. Furthermore, in the known filling level sensor, connection points of the lever wire to the bracket are very highly stressed by forces acting on the float. This requires the lever wire to be attached to the bracket in a structurally demanding and cost-intensive way (FR 2,661,497; FR 2,656,419). 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 of the simplest possible design and is as cost-effective as possible to produce.
This problem is achieved according to the invention by virtue of the fact that the guide has an apron which is arranged on the carrier part and engages over the lever wire.
As a result of this design, forces which are transmitted from the float to the lever wire are supported in the region of the lever wire by the apron so that the connection of the lever wire to the bracket is stressed to a particularly low degree. The bracket does not require a hook for the axial guidance and is therefore of particularly simple design. Since all the elements of the axial guide are arranged on the carrier part, the bracket is very simple to produce using injection molding technology. As a result, the filling level sensor according to the invention is particularly cost-effective.
BRIEF SUMMARY OF THE INVENTION
In accordance with one advantageous development of the invention, this apron is of particularly simple design and has very small dimensions if it is of bar-shaped design. As a result, the filling level sensor according to the invention can easily be introduced into the container through an opening which is very small in design. Furthermore, the lever wire is, as a result of this design, guided in a particularly reliable way so that the envisaged prestress of the sliding contact against the slideway is ensured at all times. Thanks to the invention, a magnetically active position sensor can also be used as a regulator, in which sensor a magnet which is arranged on the bracket is guided at a constant distance via a resistance network which is attached to the carrier part.
In accordance with another advantageous development of the invention, the pivoting of the bracket is damped only insignificantly by friction losses or by adhesion of the apron to the lever wire if the regions of the apron and of the carrier part which face the lever wire each have a narrow guideway for guiding the lever wire.
According to another advantageous development of the invention, the lever wire can be introduced particularly easily between the guideways if the guideways are spaced apart in the direction of the lever wire.
According to another advantageous development of the invention, the mounting of the lever wire is simplified further if a guideway of the carrier part is arranged on a web which is inclined in the direction of the pivot axis of the bracket.
The pivoting range of the lever wire can, according to another advantageous development of the invention, be delimited with particularly little constructional outlay if the apron is connected to the carrier part by means of arms and if the arms are designed so as to delimit the pivoting range of the lever wire.
The filling level sensor according to the invention is composed of a particularly small number of components to be mounted if the apron is produced in one piece with the carrier part. As a result, for example, the bracket can firstly be mounted on the carrier part. Then, the lever wire can be pushed through between the two guideways of the carrier part and of the apron.
The mounting of the filling level sensor according to the invention is simplified further if the apron is attached to the carrier part by means of a latching connection.
According to another advantageous development of the invention, the apron can be arranged particularly closely to the end of the bracket if the apron is of bow-shaped design corresponding to the pivoting range of the bracket.
According to another advantageous development of the invention, the bearing of the bracket on the carrier part requires only very small dimensions to absorb high axial forces if the bracket has at least two radially protruding webs, and the carrier part has flange elements which engage over the webs and are spaced apart from one another corresponding to the dimensions of the webs. In order to mount the device, the webs of the bracket are simply inserted between the flange elements and then pivoted in under the flange elements.
According to another advantageous development of the invention, the bearing of the bracket has particularly low friction if the webs have sliding elements which bear on the flange elements and/or the carrier part.
According to another advantageous development of the invention, the bearing of the bracket on the carrier part is of a particularly simple structural design if the bracket has a drilled hole, and the carrier part has a spigget which penetrates the drilled hole.
The lever wire could, as in the case of the known filling level sensor, be attached to the top of the bracket. However, as a result of this, the filling level sensor has very large dimensions. The dimensions of the filling level sensor according to the invention are reduced if a latching element of the bracket for holding the lever wire is arranged in a lateral region. As a result, the lever wire is located in a space saving fashion in the same plane as the bracket.
The lever wire could, for example, be attached exclusively to the bracket. In order to absorb tensile or compressive forces acting on the lever wire, the attachment of the lever wire to the bracket must, however, be of particularly stable design. According to another advantageous development of the invention, the tensile and compressive forces of the lever wire are not transmitted to the bracket if the spigget of the carrier part has a drilled hole for receiving an angled portion of the lever wire. As a result, the bracket can be of particularly light and compact design.
According to another advantageous development of the invention, when the lever wire is inserted into the drilled hole of the spigget the bracket can be mounted and dismounted if the bracket has a recess which extends from the angled portion of the lever wire to above one of the webs.
Forces acting on the lever wire could cause the bracket to tip between the bearing and the apron. However, according to another advantageous development of the invention, the tipping does not bring about incorrect signals of the reg
Larkin Daniel S.
Loo Dennis
Mannesmann VDO AG
Mayer Brown & Platt
Speer Richard A.
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