DRAWING
A plurality of exemplary embodiments of the invention are shown in the drawing and are explained in further detail in the ensuing description.
FIG. 1 shows a plan view of a force measuring instrument in a first exemplary embodiment of the present invention;
FIG. 2 shows a side view of the force measuring instrument shown in FIG. 1;
FIG. 3 is a perspective view of a pedal assembly, in which a force measuring instrument in a second exemplary embodiment of the present invention is used;
FIG. 4 is a perspective view of the pedal assembly shown in FIG. 3, with the pedal plate shown in dashed lines;
FIG. 5 is a perspective view of the force measuring instrument shown in FIGS. 3 and 4;
FIG. 6 is a side view of the pedal assembly shown in FIGS. 3-5;
FIG. 7 is an enlarged perspective view of the force measuring instrument shown in FIG. 5, in the second exemplary embodiment of the present invention; and
FIG. 8 shows an enlarged view of the side view, shown in FIG. 6, of the force measuring instrument in the second exemplary embodiment.
DESCRIPTION OF THE EXEMPLARY EMBODIMENTS
In FIGS. 1 and 2, a first exemplary embodiment of the force measuring instrument of the invention is shown. This force measuring instrument 1 is used in a pedal assembly of a motor vehicle. As shown in FIG. 1, the force measuring instrument 1 includes a carrier plate 3 and a tongue element 4. The tongue element 4 is formed integrally with the carrier plate 3 and is made for instance by stamping. As shown in FIG. 2, the tongue element 4 protrudes partly from the carrier plate 3. The tongue element 4 is embodied resiliently, so that when the pedal is not actuated, the tongue element returns to its outset position. The tongue element 4 also has two through openings 8 and 9, through which bolts are guided in order to join the tongue element 4 to a pedal plate 2.
As shown in FIG. 1, the tongue element 4 is embodied in barlike fashion, and an air gap 7 is formed between the tongue element 4 and the carrier plate 3. A magnetically sensitive element 6, such as a Hall element or a magnetoresistive element, is disposed in this air gap 7. As shown in FIG. 1, a magnet 5 is also provided, which is disposed on the carrier plate 3 in such a way that the magnetically sensitive element 6 is disposed between the magnet 5 and the tongue element 4.
The carrier plate 3 is also connected to a brake pedal lever 10, which is rotatably supported on a bearing 11. The two side parts of the carrier plate 3 are embodied as stops 12 and 13. The magnetic flux F of the force measuring instrument is also shown in FIG. 1. From the magnet 5, the magnetic flux passes via the magnetically sensitive element 6 and the air gap 7 to reach the tongue element 4, and it is returned to the magnet via the carrier plate 3 and the two lateral stops 12 and 13.
The mode of operation of the force measuring instrument in the first exemplary embodiment will now be described. When a driver initiates a braking event by exerting a pedal force on the pedal plate 2, the tongue element 4 that is solidly joined to the pedal plate 2 is rotated about an axis, not shown, at which the tongue element 4 is joined to the carrier plate 3. In other words, by means of the force exerted, the tongue 4 is pressed in the direction of the carrier plate 3 until it is located in the same plane as the carrier plate 3. This changes the magnetic field in the magnetically sensitive element 6, since the resultant field geometry in the air gap 7 is changed. In other words, the entrance of the tongue element 4 into the magnetic circuit F changes the flux density in the magnetically sensitive element 6. This change is analogous to the bending or motion of the tongue element 4, which in turn is analogous to the force exerted on the brake pedal 2. Thus the exerted force is converted directly into an altered magnetic field intensity.
As can be seen from FIG. 2, the tongue element 4 can be moved until it contacts the pedal plate 2 at the stops 12, 13 of the carrier plate 3. When a maximal pedal force is thus exerted, the tongue element 4 is located in the same plane as the carrier plate 3 and thus in the same plane as the magnetic circuit F. The pedal plate 2 is braced against the stops 12, 13 of the carrier plate 3 at this time. When the driver lifts his foot from the brake pedal, the tongue element 4 returns to its outset position, because of its resilient design. In the exemplary embodiment described, the tongue element 4 is made from spring steel. However, it is also conceivable to dispose spring elements or rubber elements on the tongue element 4, which return the tongue element 4 to its outset position.
In FIGS. 3-8, a second exemplary embodiment of a force measuring instrument of the invention is shown. Identical parts are identified by the same reference numerals as in the first exemplary embodiment.
As shown particularly in FIGS. 7 and 8, the force measuring instrument 1 again includes a carrier plate 3, which is solidly joined (see FIGS. 3-6) to a brake pedal lever 10 supported rotatably about a bearing 11. A tongue element 4 is also provided, which is formed integrally with the carrier plate 3. The movable, resiliently embodied tongue element 4 has two through openings 8 and 9, which receive two bolts 17 and 18 for joining the tongue element 4 solidly to a pedal plate 2.
As shown in FIG. 7, the tongue element 4 is embodied in barlike fashion. An air gap 7 is provided on the lower end of the barlike tongue element 4, between the tongue element 4 and the carrier plate 3. As shown in FIG. 8, the air gap 7 has a width b. A first magnet 5 is also disposed on the lower end of the tongue element 4. A second magnet 15 is disposed on the carrier plate 3, in such a way that it protrudes from the carrier plate 3 into the air gap 7. A printed circuit board 16 and a magnetically sensitive element 6 are also disposed on the second magnet 15 (see FIG. 8).
As also shown in FIG. 8, the two magnets 5 and 15 are disposed such that they have opposite polarity. In the sectional view of FIG. 8, the magnetic circuits F of the two magnets 5 and 15 are shown. As a result of this disposition of the two magnets 5 and 15, and because of the polarization of the two magnets 5 and 15 in the same direction, a pronounced field displacement occurs in the air gap 7. A strong measurement effect can be assured as a result. Moreover, because of this, the angle by which the tongue element 4 protrudes from the carrier plate 3 can be selected to be relatively small. This results in a low structural height of the force measuring instrument 1.
The function of the force measuring instrument in the first and second exemplary embodiment is equivalent to that in the first exemplary embodiment. The change, picked up by the magnetically sensitive element, in the magnetic field density is converted into a signal, which is delivered to a brake control device by means of the printed circuit board 16.
As shown in FIG. 8, the force measuring instrument 1 in the second exemplary embodiment additionally has a stop element 14, which is mounted on the pedal plate 2. This stop element 14 acts as a mechanical stop, in order to furnish a high overload capacity. As a result, the driver can even perform panic braking, in which peak forces of over 3000 Newtons can occur, without damaging the force measuring instrument. A high overload capacity of the force measuring instrument is thus assured.
In summary, the present invention thus relates to a force measuring instrument, having a carrier plate 3, at least one magnet 5, and at least one magnetically sensitive element 6. An elastically disposed tongue element 4 protrudes at least partly from the carrier plate 3 and is joined to a plate element 2. Between the tongue element 4 and the carrier plate 3, an air gap 7 is formed, in which the magnetically sensitive element 6 is positioned. The force to be measured, delivered via the plate element 2, leads to a relative motion between the end, toward the air gap, of the tongue element 4 and the carrier plate 3. This causes a change in the magnetic field geometry in the air gap 7. The present invention also relates to a method for detecting a force.
The above description of the exemplary embodiments of the present invention is meant solely for illustrative purposes and not for the sake of limiting the invention. Various changes and modifications are possible within the context of the invention without departing from the scope of the invention or its equivalent.
Patent Application
20080092669
