Patent ID: 12235134

DETAILED DESCRIPTION

As can be seen inFIGS.1and2, the represented exemplary embodiment of a magnetic measuring device20according to the disclosure for contactless detection of a movement of a body10comprises a sensor16, which is connected in a rotationally fixed manner to the body10, and a measurement transducer24which is arranged in a stationary manner. Depending on the movement of the body10, the sensor16influences at least one magnetic variable of a magnetic field detected by the measurement transducer24.

As can further be seen inFIGS.1and2, the sensor16for the magnetic measuring device20comprises a permanent magnet16A which is connected in a rotationally fixed manner to the body10and moves together with the body10. In this case, a plastic bonded permanent magnetic material is injection molded onto the body10as an extension and forms a free end of the body10as a permanent magnet16A.

As can further be seen inFIGS.1and2, in the exemplary embodiment represented, the moving body10is designed as a rotatably mounted shaft12, the free end of which with the permanent magnet16A projects into a hollow space28which is formed in a connection adaptor9. In an alternative exemplary embodiment which is not represented, the moving body10is designed as a translationally mounted rod. As can further be seen inFIG.1, the shaft12is designed as a motor shaft and is rotatably mounted in a motor bore7.1, which is introduced into a pump housing7, via a motor bearing7.2. The connection adaptor9is pressed into the motor bore7.1via press-in ribs9.1.

As can further be seen inFIG.1, the measuring device20comprises an electronic sensor system22which is arranged on a printed circuit board26and which has a measurement transducer24and a sensor interface25. In the represented exemplary embodiment of the measuring device20, the sensor interface25and the measurement transducer24are arranged in a common ASIC module23. As can further be seen inFIG.1, the printed circuit board26is held on the connection adaptor9in such a way that the distance between the measurement transducer24and the sensor16is as small as possible. In the exemplary embodiment represented, the measurement transducer24is arranged in a recess in the connection adaptor9at a dividing wall above the hollow space28, into which the free end of the shaft12with the permanent magnet16A projects. The sensor interface25outputs output signals of the measurement transducer24to an evaluation and control unit which is not represented, which signals represent the influence of the magnetic field detected by the measurement transducer24. The evaluation and control unit is arranged in a superordinate control apparatus, for example, and evaluates the output signals of the measurement transducer24received from the sensor interface25, in order to calculate a current rotation angle and/or a current rotation speed of the shaft12. In the exemplary embodiment represented, the shaft12is designed as a motor shaft of a controlled direct current motor or an EC motor (EC motor: electronically commutated motor). In the exemplary embodiment represented, the permanent magnet16A is diametrically magnetized for generating a periodic change in the magnetic field depending on the rotational movement of the shaft12. In an alternative exemplary embodiment which is not represented, the permanent magnet16A is magnetized at its front surface or magnetized in a multipolar manner.

As can further be seen inFIGS.1and2, the outer form of the permanent magnet16A is adapted to the contour of the measuring space28, wherein the transition between the front surface and lateral surface of the permanent magnet16A is designed to be rounded. The rounded edges of the permanent magnet16A facilitate the insertion of the free end of the shaft12into the hollow space28in the connection adaptor9. In the exemplary embodiment represented, the outer diameter of the permanent magnet16A corresponds to the outer diameter of the shaft12. In order to improve the homogeneity of the magnetic field of the permanent magnet16A, the permanent magnet16A is designed with an outer diameter which is as large as possible. In one exemplary embodiment of the sensor16which is not represented, the permanent magnet16A can have a stepped design. This means that the outer diameter of the permanent magnet16A is designed to be larger or smaller than the outer diameter of the shaft12.

As can further be seen inFIGS.1and4, a fixing geometry14is formed at the end of the shaft12, which fixing geometry is enclosed by the permanent magnet16A, such that a radial and axial positive engagement is formed between the permanent magnet16A and the shaft12.

In the exemplary embodiment represented, the fixing geometry14is designed as a protruding structure14with a mushroom-shaped cross section and a surrounding undercut. This means that a cap14.1of the mushroom-shaped cross section has a larger diameter than a stem14.2of the mushroom-shaped cross section. In one exemplary embodiment of the sensor16which is not represented, the fixing geometry14can be designed as a recess with a mushroom-shaped cross section and a surrounding undercut. In one further exemplary embodiment of the sensor16which is not represented, a non-magnetic section is formed between the permanent magnet16A and the shaft12as a magnetic insulation section between the permanent magnet16A and the shaft12, in order to advantageously reduce an outflow of the useful magnetic field of the permanent magnet16A into the soft magnetic shaft12.

As can further be seen inFIG.3, in the method100according to the disclosure for fixing a sensor16to a moving body10, in step S100, a body10is provided at the free end of which a fixing geometry14is formed. In step S110, the free end of the body10with the fixing geometry14is inserted into a cavity5represented inFIG.5of an injection molding tool1. In step S120, plastic bonded permanent magnetic material is introduced into the cavity5of the injection molding tool1via a filler opening3, such that the cured plastic bonded permanent magnetic material forms a free end of the body10as an extension of the body10.FIG.5shows the injection molding tool1after the plastic bonded permanent magnetic material has been introduced into the cavity5. In step S130, the permanent magnetic material is magnetized in order to form a permanent magnet16A. In one alternative exemplary embodiment of the method100according to the disclosure which is not represented, the magnetization of the permanent magnet does not take place in a separate step S130, but rather is already carried out in step S120during the filling and curing process of the plastic bonded permanent magnetic material, so that the method100according to the disclosure for fixing a sensor16to a moving body10can be completed more quickly.

In the exemplary embodiment represented, the permanent magnetic material is integrated into granules of an injection-moldable plastics material before being introduced into the cavity5of the injection molding tool1. In one alternative exemplary embodiment which is not represented, the permanent magnetic material in powder form is mixed with injection-moldable plastics material before being introduced into the cavity5of the injection molding tool1. The fixing geometry14of the body10is designed in such a way and the plastic bonded permanent magnetic material is introduced into the cavity5of the injection molding tool1in such a manner that, after curing the introduced plastics material, a radial and axial positive engagement is formed between the permanent magnet16A formed therefrom and the fixing geometry14of the body10.

Embodiments of the sensor according to the disclosure and of the method according to the disclosure for fixing a sensor to a moving body10can also be used for the detection of translational movements of a body10designed as a rod relative to a measurement transducer24. In the case of the body10designed as a rod, the influence of the magnetic field detected by the measurement transducer24is evaluated, in order to calculate a current distance covered and/or a current speed of displacement of the rod.