| Title of Invention | ARRANGEMENT FOR CALIBRATING A TORQUE SENSOR |
|---|---|
| Abstract | The invention relates to an arrangement for calibrating a torque sensor (7) fixed on one side, wherein a calibrating lever (11) provided with an outside calibrating weight at a predefined distance from the sensor axis (12) is fixed to the sensor free flange (9). In order to reduce or eliminate an irregular bending moment influencing the torque sensor (7) through the calibrating lever (11), said lever is angled, whereby a fictive contact point of the calibrating weight is offset, at least approximately, on the plane of rotation (17) corresponding to the external contact surface (14) of the sensor flange (9) bearing the calibrating lever (11). |
| Full Text | WO 2006/099641 Description ARRANGEMENT FOR CALIBRATING A TORQUE SENSOR The invention relates to an arrangement for calibrating a torque sensor which, on the one hand, may be rotationally connected without bearings to a drive shaft flange and, on the other hand, to an output shaft flange and substantially consisting of two axially spaced-apart flanges with a torque transmission region and a torque measuring region located therebetween, comprising at least one calibrating lever at least on one side which, for calibrating, may be attached to the associated sensor flange instead of one of the shaft flanges, on the outer end(s) thereof remote from the sensor axis at least one calibrating weight being able to be attached at a defined distance from the sensor axis. Torque sensors of the aforementioned type are known, amongst others, from DE 199 36 293 A1 and are, for example, preferably used on test beds for internal combustion engines, transmission units, drive trains and the like, therefore, as they may be installed easily and with a small space requirement and, as a result of their low mass and small dimensions, do not influence or at least only slightly influence the torque characteristic to be measured. For accurate measurements, such sensors have to be calibrated at least from time to time, i.e. the measuring signals supplied by the sensor and provided in the attached evaluation unit have to be related to actual torques acting on the sensor. To this end, conventionally, a preferably two-armed calibrating lever is fastened to one of the sensor flanges, the other sensor flange either remaining connected to the blocked drive shaft flange or output shaft flange or, however, after a complete removal of the sensor, being installed on a separate fixed auxiliary device. By attaching a known calibrating weight to the calibrating lever at the known distance from the - 2 - sensor axis, a torque which acts in a precisely defined manner thus results, which is associated with the respective measured value, and as a result of which a calibration curve may be produced. This relatively simple manner of calibrating such sensors, however, has the principal drawback that as a result of the calibrating lever which is fastened without separate support bearings to the free sensor flange, not only a pure torque loading of the sensor results, but also lateral forces and bending forces have an effect, which invalidate the measurement result and thus the calibration. These irregular loads (which also include, for example, the axial loads of such sensors, but which do not occur however in the disclosed case) therefore always have to be restricted to values which are provided in the data sheets of the torque sensors, as then the anticipated measuring inaccuracies may be expected and also any damage to the sensors may be reliably prevented. It is the object of the present invention, to improve a calibrating arrangement of the aforementioned type such that the aforementioned irregular loads of the torque sensor are reduced and thus the calibration accuracy and finally the actual measuring accuracy of the calibrated torque sensor is increased. This object is achieved with an arrangement of the aforementioned type, by the imaginary point of application of the calibrating weight on the calibrating lever being at least approximately located in or - relative to the torque sensor - inside the plane of rotation located perpendicular to the sensor axis and spanned by the outer contact face of the sensor flange bearing the calibrating lever. In this simple manner, the bending moment applied by calibrating levers of the previously used type in such calibrating arrangements to the sensor to be calibrated (additionally to the defined torque), may be reduced or completely - 3 - eliminated, so that only the lateral torque remains as the single irregular loading as a result of the action of the force from a different angle. With conventional arrangements of the aforementioned type, since the influence of irregular lateral torques and bending moments on the accuracy may be estimated to be approximately the same size, the error of measurement is thus approximately halved and/or the calibration accuracy is doubled. In a further embodiment of the invention, it is provided that the calibrating lever is of angled configuration, the angled portion preferably being located on the inside, in the vicinity of the fastening to the sensor flange. Thus a very stable design of the calibrating lever results which, in a further embodiment of the invention, preferably consists of at least two substantially straight parts, which are installed together, offset in the direction of the sensor axis, which considerably simplifies the manufacture. The imaginary point of application of the calibrating weight may, in a further preferred embodiment of the invention, be adjustable in the axial and/or radial direction, preferably by the adjustable fastening of the actual weight pan and/or the adjustable installation of the parts of the calibrating lever relative to one another. Thus if required, not only the calibrating torque to be applied may be accurately set but also the compensation of the bending moment may be influenced, which may be compensated in this manner, for example also by different adapter flanges or similar connectors. The invention is described hereinafter in more detail with reference to the embodiments shown partially schematically in the drawings. Figure 1 shows, therefore, an internal combustion engine test bed with the installed torque sensor of the type to be calibrated by an arrangement according to - 4 - the present invention, Figure 2 shows a calibrating arrangement according to the previous prior art, Figure 3 shows a calibrating arrangement according to the present invention and Figure 4 shows the arrangement according to Figure 3 in a perspective view. According to Figure 1 an internal combustion engine 2 positioned on base elements 1 is connected to an electric drive machine and/or loading machine 4 on a test bed 3, not shown in more detail, the drive shaft flange 5 on the internal combustion engine side and the output shaft flange 6 on the electric machine side (or vice versa) being directly connected to a torque sensor 7 arranged therebetween. Such sensors 7 are shown in Figures 2 to 4 in slightly more detail and, for example, are known from the aforementioned DE 199 36 293 A1. They may be easily installed by means of flange screws, not shown in more detail here, and without additional bearings, connecting shafts or the like and offer as a result of small dimensions and low mass the advantage that the measurement of the torque transmitted between the internal combustion engine 2 and the electric machine 4 (or vice versa) is influenced as little as possible. Further details of such test beds 3 and/or further measuring devices and power supply devices and the like are not shown here for the sake of simplicity. For calibrating the torque sensor 7, said torque sensor may either be completely removed from between the flanges 5 and 6 and fastened on one side to a fixed auxiliary device, not shown here, (in the same and/or similar manner as to one of the flanges 5, 6) , or however remain fastened to the internal combustion engine 2 and/or the flange 5 or -preferably - to the electric machine 4 and/or the flange 6, whilst the other side (with the machine 4 and/or 2 removed or not yet installed) remains free - in both cases the respective machine 2, 4 and/or the respective shaft flange - 5 - 5, 6 may be blocked against rotation. On the flange which remains free, of the two axially spaced-apart flanges 8, 9 of the torque sensor 7 (between which the torque transmission region and the torque measuring region 10 of the torque sensor 7 visible in Figures 2 and 3 are located) the calibrating lever 11 (which is two-sided according to Figures 2 to 4) is thus attached, to the outer ends 13 of which, remote from the sensor axis 12, calibrating weights, not shown here, are able to be attached at a defined distance from the sensor axis 12. Thus an accurately defined torque is exerted on the torque sensor 7, which together with the measuring signals which may be determined thereby, is used for calibration. In the arrangement shown in Figure 2, according to the previously known prior art, as is conventional, between the actual calibrating lever 11 and the outer contact face 14 of the sensor flange 9 bearing the calibrating lever 11 a further adapter flange 15 (for allowing the use of the calibrating lever 11 on different sensors 7) is arranged, whereby the plane of rotation 16 of the imaginary point of application of the calibrating weight on the calibrating lever 11 is displaced outwardly relative to the plane of rotation 17 spanned by the outer contact face 14 of the sensor flange 9 by the distance 18 from the torque sensor 7 (i.e. away from the fastening of the sensor flange 8 which is to be imagined at the top in Figure 2) . The bending moment resulting therefrom (at least the distance 18 from the calibrating weight) represents an irregular loading of the torque sensor, which in the known manner invalidates the torque measurement and thus the calibration. In order to remove and/or at least partially eliminate this irregular bending moment, with the arrangement according to the invention according to Figure 3, the calibrating lever 11 is now configured such that the plane of rotation 16 spanned by the imaginary point of application of the - 6 - calibrating weight coincides with the plane of rotation 17 positioned perpendicular to the sensor axis 12 and spanned by the outer contact face 14 of the sensor flange 9 bearing the calibrating lever 11, whereby the distance 18 (according to Figure 2) becomes zero. Since the manufacturers of such torque sensors 7 generally apply the irregular loads and/or the permitted amounts thereof to the outer contact face 14 and/or the imaginary plane of rotation spanned thereby, the irregular bending load to be considered is at least theoretically completely eliminated, therefore, so that the calibrating accuracy may be substantially improved. As may be easily imagined in the arrangement according to Figure 3, the position of the plane of rotation 16 (point of application of the calibrating weight), however, may also be very easily displaced to a greater or lesser extent from the upper sensor flange 8 which is fixed for calibration (variable effective angling of the calibrating lever 11) whereby a specific influence is possible on the actual remaining irregular bending moment. The calibrating lever 11 of angled configuration according to Figures 3 and 4 advantageously bears the angled portion 19 on the inside, in the vicinity of the fastening to the sensor flange 9, which affords greater stability. The calibrating lever 11 consists of three substantially straight parts 20, 21, 22 which are installed together, offset in the direction of the sensor axis 12, which simplifies the manufacture. The imaginary point of application of the calibrating weights may be adjusted in the axial and/or radial direction, preferably namely by adjustable fastening of the actual weight pans 23 (see Figure 4) and/or adjustable installation of the parts 20, 21, 22 of the calibrating lever 11 relative to one another. WO 2006/099641 - 7 - CLAIMS 1. Arrangement for calibrating a torque sensor (7) which, on the one hand, may be rotationally connected without bearings to a drive shaft flange (5) and, on the other hand, to an output shaft flange (6) and substantially consisting of two axially spaced-apart flanges (8, 9) with a torque transmission region and a torque measuring region (10) located therebetween, comprising at least one calibrating lever (11) at least on one side which, for calibrating, may be attached to the associated sensor flange (8, 9) instead of one of the shaft flanges (5, 6), on the outer end(s) (13) thereof remote from the sensor axis (12) at least one calibrating weight being able to be attached at a defined distance from the sensor axis (12), characterized in that the imaginary point of application of the calibrating weight on the calibrating lever (11) is at least approximately located in or - relative to the torque sensor (7) - inside the plane of rotation (17) located perpendicular to the sensor axis (12) and spanned by the outer contact face (14) of the sensor flange (9) bearing the calibrating lever (11). 2. Arrangement according to Claim 1, characterized in that the calibrating lever (11) is of angled configuration, the angled portion (19) preferably being located on the inside, in the vicinity of the fastening to the sensor flange (9). 3. Arrangement according to Claim 2, characterized in that the calibrating lever (11) consists of at least two substantially straight parts (20, 21, 22) which are installed together, offset in the direction of the sensor axis (12). - 8 - 4. Arrangement according to one of Claims 1 to 3, characterized in that the imaginary point of application of the calibrating weight is adjustable in the axial and/or radial direction, preferably by the adjustable fastening of the actual weight pan (23) and/or the adjustable installation of the parts (20, 21, 22) of the calibrating lever (11) relative to one another. The invention relates to an arrangement for calibrating a torque sensor (7) fixed on one side, wherein a calibrating lever (11) provided with an outside calibrating weight at a predefined distance from the sensor axis (12) is fixed to the sensor free flange (9). In order to reduce or eliminate an irregular bending moment influencing the torque sensor (7) through the calibrating lever (11), said lever is angled, whereby a fictive contact point of the calibrating weight is offset, at least approximately, on the plane of rotation (17) corresponding to the external contact surface (14) of the sensor flange (9) bearing the calibrating lever (11). |
|---|
| Patent Number | 279978 | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Indian Patent Application Number | 3574/KOLNP/2007 | |||||||||
| PG Journal Number | 06/2017 | |||||||||
| Publication Date | 10-Feb-2017 | |||||||||
| Grant Date | 06-Feb-2017 | |||||||||
| Date of Filing | 21-Sep-2007 | |||||||||
| Name of Patentee | AVL LIST GMBH | |||||||||
| Applicant Address | HANS-LIST-PLATZ 1 8020 GRAZ | |||||||||
Inventors:
|
||||||||||
| PCT International Classification Number | G01L 25/00 | |||||||||
| PCT International Application Number | PCT/AT2006/000109 | |||||||||
| PCT International Filing date | 2006-03-16 | |||||||||
PCT Conventions:
|
||||||||||