Torque sensor with a strain gauge

The invention relates to a torque sensor according to the Preamble of claim 1 with a Dehnmeßstreifenanordnung. The torque sensor has a torque introductory and drehmomentausleitende side and is about these two terminal pages mechanically in the transmission path to be measured Torque introduced.

There are sensors for measuring a torque known in de NEN strain gauges which are connected as a measuring bridge, on egg ner cylinder surface over which the torque to be measured is transmitted at an angle of 45 ° to the surface line of the arranged cylinder.

The strain gauges extend Consequently, over a certain axial range and convert the of a torque-induced mechanical strains of a Measuring body serving cylinder jacket into corresponding electrical Measurement signals to. Besides such sensors with Dehnmeßstreifenanord tion are also those with spring body geometries and those with a magnetostrictive measurement layer. See, for example, the Patent EP 0285259 B1, known.

It is often desirable to sensors with clotting possible to have gen axial dimensions available to the increase de demand for more compact, cost-effective construction of torque-generating machines and the associated, DREHMO to fulfill ment transmitting parts and to such sensors also to modify or in confined conditions. For swing torque sensors which function on the principle of a magneto strictive measuring film is based, realizations are already a relatively short axial length have been proposed. So is at one in the patent US 4,697,460 disclosed Sen sor a magnetic disc arranged transversely to the axis of rotation, wel cher axial magnetic sensor array with excitation and Sensor coil is juxtaposed with what the reduction of axia sets len Eaulänge limits. not previously published in the German Patent Application P 43 33 199.8 is a sensor angege ben, wherein the axial extent of the magnetic measurement layer bearing cylindrical surface, the axial length the sensor determines.

Also for based on the Dehnmeßstreifenprinzip Drehmomentsen sors are already variously realizations with relatively short axial length have been proposed. So is a gat tion according to torque sensor in the publication WO 92/18840 discloses. This sensor consists of Meßkörperbe rich of four radial webs, the flush on one axial to the radially inward or outward adjacent Drehmomentübertra tion share run, uniform in the radial direction have axial thickness and on its outer side with the jeweili provided gen strain gauges. Accordingly, the thickness of the wearing Dehnmeßstreifenanordnung to the axial length of this sensor at. More torque sensors with Dehnmeßstreifenanordnung and relatively low axial length are described in the patents DE 27 08 484 C2 and DE 37 15 472 C2 and Offenlegungsschriften DE 32 13 319 A1 and DE 42 08 522 A2. It is in DE 32 13 319 A1 a sensor is disclosed, wherein the measuring body consists of four radial webs whose axial thickness along the Radial extension is constant while its width in scope direction of the associated sensor body along the radial direction decreases from the inside outwards. In the DE 42 08 522 A2 shown, shear-absorbing torque sensor is the measuring body consists of four radial webs with respect to the radial inside or outside subsequent torque transmission parts reduced, along the radial direction constant axial Dic ke what in by both sides introducing recesses a associated sensor disc body is achieved.

It is further known, the electrical sensor signals and the power supply of the sensor or via telemetric On to transmit orders of contactless. See, for example, the Offenle tion regulations DE 38 25 706 A1 and DE 40 25 279 A1.

The invention is the technical problem of providing a torque sensor with Dehnmeßstreifenanordnung underlying of a comparatively small axial length and vorteilhaf te measuring properties has.

This problem is caused by a torque sensor with the Merkma len of patent claim 1. The Dehnmeßstreifenanordnung is on a the axis of rotation in a transverse plane vice reproduced, circular area of ​​a disc body, is the annular region of sufficiently small thickness, and upon exposure to a torque about the radially inner outside subsequent torque transmitting parts of the disks body mechanical stresses, eg. as shear stresses to erzeu gen, which are sensed by the Dehnmeßstreifenanordnung. On thus constructed sensor can in extreme axial short mounting position can be realized because the axial extent of Schei benkörpers because of the measuring body in an axial plane lying strain gauges not by the sensed elements is determined, but the disk body axially to a Dic ke can be reduced, which even the torque Next line required, mechanical stability ensured. There the neces readily for Dehnmeßstreifenanordnung sary electrical energy and of the strain gages electrical signals generated by wire or wirelessly with means electrical or electronic components with relatively be transferred small dimensions, the reduction is the axial Sensorbaulänge even through this energy and Si gnalübertragungskomponenten limited. Metrologically advantageous, very homogeneous shear stresses for detection by the extension measurement stripes are achieved in that the axial thickness of the circle Meßkörperbereichs annular radially from the inside towards the outside decreases.

A development of the invention according to claim 2 allows structurally simple and thus cost-effective manufacture of Torque sensor by the intended disk bodies, from designed where the sensor is constructed, are such that they far can be continuously manufactured as turned parts. Which in this Refinement intended second disk body is particularly for a realization of a development according to claim 3 expedient is achieved with which that Drehmomenteinlei tion and the Drehmomentausleitung for the sensor to about the same radius are what both from the point of Torque transmission than is montage technically advantageous because the sensor on the torque and on the introductory DREHMO mentausleitenden side respectively at the same radial height at the associated, adjacent portions of the torque transmission is gone fastened.

In claim 4 a sensor implementation is indicated in which the electrical energy for Dehnmeßstreifenanordnung and are transmitted wirelessly from the latter generated test signals. To build such an electrical device to the skilled man a variety of electrical and / or electronic communications components familiar to possess sufficiently low dimensions, which does not have the anyway to ensure REQUIRED chen mechanical stability necessary mechanical dimen gen of the sensor disk body go, so that the Reduzie not by this type of electrical tion of the axial length Signal transmission is limited. This is also the measure acquisition ensures the electrical signal transmission to and carried out by the sensor on its outer periphery. A particularly advantageous embodiment of such a device is by given claim. 5 With the electric A claimed there direction takes place a wireless electric signal transmission to and from the sensor or from radially outward, wherein the clamping DC converter module within the or the sensor disc body is added, so that here again no increase in axial Sensorbaulänge due to its electrical signal processing is sometimes necessary. Optionally necessary jointing tion lines from the voltage converter module for radial Sensorau ßenseite and / or Dehnmeßstreifenanordnung can so in Aus recesses or holes in the disc or the bodies of its sensor out that, despite small axial Sensorbau not protrude axially length over the sensor body.

Preferred embodiments of the invention are in the Zeichnun gene shown and described below. Here zei gene:

<b>Fig.</b> 1 is a longitudinal section through a torque sensor with Dehnmeßstreifenanordnung and Cordless Electric Signal transmission with short axial length and

<b>Fig.</b> 2 is a perspective view of an over that from <b>Fig.</b> 1 structurally slightly modified, depending but functionally identical torque sensor, wherein the Illustrate the internal structure of a quarter of the is sensor broken away,

<b>Fig.</b> 3 is an electrical equivalent circuit diagram of a further Sensor variant.

The in <b>Fig.</b> 2 torque sensor shown corresponds to to ge ringfügige modifications in mechanical construction, in particular as to the precise cross-sectional shape of the ticket used benkörper and the course of circuit leading drilling this disk bodies, that of <b>Fig.</b> 1, why all the relevant parts of the sensor of <b>Fig.</b> 2 are provided with the same reference numerals as for the sensor of <b>Fig.</b> 1 are used, so that the subsequent Description on both sensors relates together unless is especially distinguished.

The torque sensors shown consist of a first Disk body (<b>1</b>) And a second disk body (<b>9</b>). Both Disk body (<b>1</b>. <b>9</b>) Are with little effort as their Central axis (<b>2</b>manufactured) rotationally symmetrical turned parts, in which then only still below mentioned holes are inserted. The first disk body (<b>1</b>) consists of a radially inner torque transmitting part (<b>3</b>), A radially external torque transmitting part (<b>4</b>) And between these Torque transmission parts (<b>3</b>. <b>4</b>) Lying, annular Area (<b>5</b>) With a comparatively small axial thickness (d₂) the latter being more particularly between the inner radius (r₂) of radially outer (4) and the outer radius (r₁) of the radially inner Torque transmitting part (<b>3</b>) Extends. This reduced Thickness (d₂) results in that when passing a torque through the first disk body (<b>1</b>) In the annular Area (<b>5</b>) Significant shear stresses occur during the In contrast with significantly greater axial extent (d, d₁) designed torque transmission parts (<b>3</b>. <b>4</b>) mechanically voltage solid remain. These shear stresses may come from a Dehnmeßstreifenbrücke (<b>6</b>), Which on one side for this purpose the annular region (<b>5</b>) Is arranged, is detected and in electrical signals are converted. The strain gages bridge (<b>6</b>) Is located within a case of both sides the annular region (<b>5</b>) For the formation of the same in the first disk body (<b>1</b>) Introduced, annular Ausneh sions (<b>22</b>) Within a portion of the annular measuring body (<b>5</b>), In which the shear stresses. Around homogeneous possible shear stresses in circular measurement body (<b>5</b>to produce), the latter is, in the sensor of <b>Fig.</b> 1 designed with a trapezoidal cross-section so that its axial Thickness (d₂) in the radial direction from the inner boundary radius (r₁) the outer boundary radius (r₂) decreases towards.

The radially outer torque transmitting part (<b>4</b>) Has a Hole circle (<b>7</b>), Which with a predetermined number of equidistant angular spaced screw holes includes that for the rotationally fixed attachment of the first Disk body (<b>1</b>) To one side of a component, whose Torque to be monitored by means of screw serve. While the radially inner torque transmitting part (<b>3</b>) on the side on which the annular area (<b>5</b>) the Dehnmeßstreifenbrücke (<b>6</b>) Is mounted axially outer with the Torque transmitting part (<b>4</b>) Completes, it extends (3) to on the opposite side in the radial stepped radially outer taper axially over the dimension (d₁) of the Torque transmitting part (<b>4</b>) With a contrast greater Axial length (d) addition. The second disk body (<b>9</b>) For first disk body (<b>1</b>) Running parallel to the projecting axial end portion of the radially inner Torque transmitting part (<b>3</b>) Fitted with the latter along the contact surface (<b>10</b>) Electron beam welded. Of the second disk body (<b>9</b>) Includes this externally flush with the associated end face of the radially inner Torque transmitting part (<b>3</b>) Of the first disk body (<b>1</b>) decreases so that the axial length (d) of said radially inner Torque transmitting part (<b>3</b>), And thus the washer body simultaneously the entire axial length of the represents torque sensor.

The second disk body (<b>9</b>) Is on the same radius (R) such as the first disk body (<b>1</b>) Also with a hole circle (<b>8th</b>) provided that a predetermined number of at equidistant Angular spaced Schraubgewindebohrungen includes, with which the torque sensor on the circle of holes (<b>7</b>) of first disk body (<b>1</b>) Opposite side on a provided further connection part of a is torque-monitored component fastened. In this form the Screw of a bolt circle the torque introductory and screw the other Hole circle the drehmomentausleitenden elements, the choice which bolt circle (<b>7</b>. <b>8th</b>) Assumes the function, from Sensor assembly is as seen arbitrarily and after may address each drive and load machine whose Torque to be measured. The torque is therefore within the sensor from the bolt circle (<b>8th</b>) Of the second Disk body (<b>9</b>) Via the latter, on the radially inner Torque transmitting part (<b>3</b>) Of the first disk body (<b>1</b>) and over the annular area (<b>5</b>), Where it by the Dehnmeßstreifenbrücke (<b>6</b>) Sensed shear stresses induced, the radially outer torque transmitting part (<b>4</b>) of the first Disk body (<b>1</b>) Out and from there via the bolt circle (<b>7</b>) discharged, or the torque transfer history is conversely, when the torque on the bolt circle (<b>7</b>) of the first Disk body (<b>1</b>) Is introduced.

Obviously possess the <b>Fig.</b> 1 and 2 Torque sensors the technical assembly and torque transmission technology advantage that the two torque terminal-forming boltcircles (<b>7</b>. <b>8th</b>) On the same Radius (R) are the sensor and yet in a simple manner from the two rotating partial disk bodies (<b>1</b>. <b>9</b>) Is made. Alternatively, it is also possible at a slightly elevated Design effort that shown or a similar elaborate sensor constructed from a workpiece. This may possibly be linked to it, the second bolt circle (<b>8th</b>) directly on the radially inner torque transmitting part (<b>3</b>) of first disk body (<b>1</b>provide), which then fits may have modified shape by, for example, in the axially projecting portion not tapered radially, but with a constant outer radius (r₁) or even with greater decreasing radius extends outward. The second disk body (<b>9</b>) Can possibly be omitted.

Also the entire electrical part of the torque sensors <b>Fig.</b> 1 and 2 is within the by the axial length (d) of the inner torque transmitting part (<b>3</b>) of the first Disk body (<b>1</b>housed) given axial range and therefore does not increase the axial length of the sensors. specifically If the coupling of the electrical energy for the Dehnmeßstreifenbrücke (<b>6</b>) With a common telemetry system a radially outside of the sensor body (<b>1</b>. <b>9</b>) stationary arranged generator (<b>12</b>) Connected in this example kopfförmigem coupling part is formed, wherein this Generator head (<b>12</b>) A on the outer circumference of the second Disk body (<b>9</b>) Leaving an air gap (<b>21</b>) arranged electrical winding (<b>13</b>) (The sensor of <b>Fig.</b> 2 an electrically conductive, between two adjacent Pads placed severed band) opposite. The winding (<b>13</b>) Is seated in a cross-sectionally U-shaped ring member (<b>20</b>) That the in a matching recess on the outer circumference second disk body (<b>9</b>) Is added so that it in the radial Direction with the outer circumference of the second disk body (<b>9</b>) flush completes. Instead of the head-shaped coupling part The generator can also be an annular primary winding have, which the winding (<b>13</b>) On the disk body (<b>9</b>) electromagnetically koppelnd leaving an annular gap surrounds.

As from <b>Fig.</b> 2 recognized - in <b>Fig.</b> 1, the electrical Connecting lines omitted for clarity - performs a set of electrical lines (<b>19</b>) From the outside Winding or the belt (<b>13</b>) To an inside of the radially inner torque transmitting part (<b>3</b>) of the first Disk body (<b>1</b>) Arranged electronic module (<b>17</b>) Which when mounted sensor rotates along. The electronic module (<b>17</b>) sitting Here, stepped in a central, rotationally symmetrical recess (<b>18</b>) In radially inner torque transmitting member (<b>3</b>). The latter is of pot-like shape by the recess (<b>18</b>) To an axial side toward a bottom portion (<b>23</b>) This transfer part (<b>3</b>) Is limited. The Connecting lines (<b>19</b>) Are essentially radially extending through a recess (<b>16</b>) Which in the second disk body (<b>9</b>) at the the radially outer torque transmitting part (<b>4</b>facing) Range is introduced, as well as through a bore (<b>15</b>) In radially inner torque transmitting part (<b>3</b>) Is passed, of of the second disk body (<b>9</b>) Facing side of the first Disk body (<b>1</b>) To this side facing away from the area the recess (<b>18</b>) In radially inner torque transmitting member (<b>3</b>) Leads (the exact course of the bushings (<b>15</b>. <b>16</b>) for the two sensors to <b>Fig.</b> 1 and <b>Fig.</b> 2 slightly varies) As also again <b>Fig.</b> 2 visible, takes another Set of interconnections (<b>11</b>) From the radial center arranged electronic module (<b>17</b>) Through a radial bore (<b>14</b>) the radially inner torque transmitting part (<b>3</b>) to Dehnmeßstreifenbrücke (<b>6</b>). Obviously, all electrical Lines placed so that they do not have the by the two Disk body (<b>1</b>. <b>9</b>) Given external dimensions of the sensor protrude.

The sensor of <b>Fig.</b> also 1 provides protection against unauthorized Manipulations. As soon as during mounting of the shown there Sensor the Dehnmeßstreifenbrücke (<b>6</b>) Attached, the Electronic module (<b>17</b>) Of the open pot side of the inner Torque transmitting part (<b>3</b>) In the recess (<b>18</b>) used and placed the electrical connecting lines are that concerned access page for these items is with a cover plate (<b>24</b>) Covered. The latter is of the axial outer side of the first disk body (<b>1</b>) Forth in this fixed so that only by a competent person he can be nondestructively released again. The lid (<b>24</b>) extending radially to the inner radius (r₂) of the outer Torque transmitting part (<b>4</b>). Along with the on opposite side closed formation of the sensor this has the consequence that the electronic module, the Dehnmeßstreifenbrücke (<b>6</b>) And the connecting lines before secured tampering.

In <b>Fig.</b> 3 is a further variant, the torque sensor associated electrical equivalent circuit diagram shown. This sensor corresponds in its structure substantially to the top described, wherein like reference numerals insofar functionally identical elements are selected. What is different In this sensor, that the generator-side part of the electromagnetic coupling distance between the rotating Sensor part (<b>25</b>) And a surrounding the sensor, stationary component (<b>26</b>) Of a primary winding tape (<b>12</b>b) in place of head-shaped generator coupling part (<b>12</b>) consists. On the stationary component (<b>26</b>) Is a high-frequency generator unit (<b>12</b>a) mounted, on the one hand to the primary winding tape (<b>12</b>b) and on the other hand via a cable connection (<b>27</b>) With a associated evaluation (<b>28</b>) Is electrically connected. The the generator winding (<b>12</b>b) opposite winding (<b>13</b>) at the radial sensor outside is as in the above sensors of a completed line set (<b>19</b>) To the inside the sensor (<b>25</b>) Recorded electronic module (<b>17</b>) connected, which also, besides its function as voltage transformer unit has the function of a sensor signal amplifier. It can be seen a calibration resistor (<b>29</b>) On the electronic module (<b>17</b>). The Dehnmeßstreifenbrücke (<b>6</b>) Is connected to the line set (<b>11</b>) to the Electronic module (<b>17</b>) And has connected to selected Points measuring points (<b>6</b>a). Of course, the Dehnmeßstreifenbrücke (<b>6</b>) In two diametrically opposite each other interconnected half-bridges, each with two measuring points (<b>6</b>a) be divided.

In operation of the respective sensors in the Outer circumferential winding (<b>13</b>), An electric voltage with the aid of the generator (<b>12</b>; <b>12</b>a, <b>12</b>b) induces, via the electrical connecting lines (<b>19</b>) For rotating Electronic module (<b>17</b>) Out there and changed as DC voltage over the second set of connecting lines (<b>11</b>) For the electrical supply of Dehnmeßstreifenbrücke (<b>6</b>) is supplied thereto. That at the bridge diagonal of this Dehnmeßstreifenanordnung (<b>6</b>) Output measurement signal is the same electrical connection path in the reverse direction such as the electrical power supply radially outwards the generator (<b>12</b>; <b>12</b>a, <b>12</b>b) and the cable (<b>27</b>) to the evaluation (<b>28</b>) Out.

It is understood that for the skilled person in addition to the already discussed further variants of the illustrated Torque sensors are possible within the scope of the invention. So For example, another conventional type of electrical Signal transmission between the rotating sensor and the outside, be provided stationary environment. Also, the precise Design of the circular, mechanically braced Region-containing washer body and a possibly provided further disk body on the respective Application be matched. Common to all such Sensors that they have a Dehnmeßstreifenanordnung to use Drehmomentsensierung and an extremely short axial own design, since the mechanical bracing area, on the Dehnmeßstreifenanordnung sitting, in an axial plane extends. This very short axial length makes it possible, for example as a special feature, such Sensor for sensing torque in a driveline with Universal joint sliding pieces characterized in a simple manner add that the universal joint sliding pieces to a small extent are pushed apart axially, which with, in most cases is such arrangements are possible, according to which there the sensor can be used.