Force measuring cell with fastening decoupling by raised surfaces and short incisions

The inventions tion relates to an apparatus for transmitting power in a load cell, with a parallel guide with a stationary and a movable parallelogram, which are connected via parallelogram with each other, wherein the stationary parallelogram leg and / or the deflectable parallelogram one of the fastening serving part with at least two attachment areas having. Each attachment portion is provided with at least a direction perpendicular to a respective leg surface bore for securing a load carrier to the apparatus for transmitting power and / or apparatus for transmitting power to a housing or an intermediate bracket, and there are slit-shaped cuts in the respective parallelogram available.

The cuts in the fixing part of a respective parallelogram of forces serve regular decoupling of one or more attachment areas from the rest of the parallelogram and of those regions of the load cell, which serve the power receiving and power transmission as a result of acting on the movable parallelogram load. In case of using such a load cell in a scale, in particular the device for power transmission session with a housing and / or to an intermediate holder, the connection of a weighing pan or a weighing pan to the vertically movable Parallelögrammschenkel or the connection of the load cell, often by means of screws. On the one hand, the preparation of the corresponding threaded holes in the material from which the parallelogram is formed, and on the other hand especially a screwed into such a threaded screw to tensions in the material surrounding the thread. The transfer of these voltages to the rest of the load cell is preferably provided with incisions or other recesses avoided in the material of the fastening serving part of the apparatus for transmitting power or at least reduced. Such of the fixing her touching forces and stresses can cause known to confuse readings.

In the prior art transmission components with incisions or recesses in which one or more attachment portions having parts which have been disclosed.

Such an apparatus for transmitting power to a load cell with a parallelogram is in the <patcit id="pcit0001" dnum="EP0511521B1"><text>EP 511 521 B1 0</text></patcit> described. This power transmission device has at its opposite ends in the region of a vertically movable parallelogram leg or a stationary parallelogram each have an attachment means, on the one hand to fasten a load carrier and the other part to apply the cell itself to a housing. At least one of the fastening devices comprises a fastening area and a connecting area, which are decoupled by a transition region. The latter is designed as narrow as possible web so that the caused of the fasteners such as bolts force and voltage flow is kept away from the connecting portion. This principle of decoupling is in the description of the<patcit id="pcit0002" dnum="EP0511521B1"><text>EP 511 521 B1 0</text></patcit> based on various configurations of the power transmission device, in particular of their connection area and the attachment area reflected. In essence, the transition region by different shaped material cutouts, in particular in circular bores. It is further proposed to provide the discrete affixation points around annular grooves decouple the attachment points from the rest of the fastening region.

The production of the <patcit id="pcit0003" dnum="EP0511521B1"><text>EP 511 521 B1 0</text></patcit> proposed versions is relatively complex, in particular this applies to the fastening region a fastening point circumferential annular grooves.

The <patcit id="pcit0004" dnum="DE19535202C1"><text>DE 195 35 202 C1</text></patcit> discloses a load cell with a parallel guide consisting of a housing-fixed portion and a load-receiving portion, which are connected by two parallelogram link. The housing-fixed portion has in a first embodiment at least two vertically extending bores for attachment of the load cell and is provided with incisions for decoupling the Anschraubbereichs to the mounting holes around fixed to the housing by the remaining region. This is one of the top and one coming from the bottom incision, the light coming from the bottom incision is extended by a jutting horizontal part in which a bore ends.

In the second embodiment, at least two horizontally extending holes for fixing of the weighing cell on the housing are present and from the sides coming incisions, in which ends of the bores. A third likewise vertically extending notch is provided between the adjacent holes. This configuration leaves only a vertically extending web and thus separates the screwing range around the holes around the housing-fixed region, whereby the measurement of the serving area of ​​the weighing cell voltage from the fastening area and is decoupled in terms of force. In both embodiments, the horizontal and vertical cuts, the apparatus for transmitting power to enforce fully in width or in height.

A disadvantage of this configuration is that through the entire height or width of the device for power transmission in the region of the respective parallelogram penetrating cuts affecting the rigidity of the particular fixed to the housing portion and / or the load-carrying area. In particular, this is available for interception laterally acting torques no longer the entire height or width of the respective parallelogram leg.

Further devices are known from <patcit id="pcit0005" dnum="EP0501351A2"><text>EP 0501351 A2</text></patcit> and from <patcit id="pcit0006" dnum="EP1083420A2"><text>EP 1083420</text></patcit> known.

Object of the present invention is to achieve a good decoupling of the fastening serving part in the region of the respective parallelogram a power transmission device with high stability of the device for transmitting power, the measures for decoupling should be a little complicated in production.

This object is achieved with the features of claim 1.

Advantageous developments of the invention are subject of the dependent claims 2 to. 13

For an apparatus for transmitting power in a load cell, with a parallel guide with a stationary and a movable parallelogram, which are connected via parallelogram with each other, the stationary parallelogram leg and / or the deflectable parallelogram side on one of the fastening serving part with at least two attachment areas. Each fastening area is substantially defined by a fastening surface and the length of a hole running perpendicularly thereto for securing a load carrier to the force-transmitting device and / or the force-transmitting device to a housing or to an intermediate holder. There are first rectilinear slot-shaped incisions in each parallelogram present which separate the attachment of serving part from the rest of the parallelogram. The attachment regions have compared to the respective Parallelogrammschenkeloberfläche on projecting mounting surfaces. The first slot-shaped incisions extend through the parallelogram in only part of the width and the height of the power transmission device, which means they are limited in areal extent, with their respective expansion corresponds parallelogram essentially the extent of any fixing region. A fastening area is thus defined in its extent substantially throughout its mounting surface and perpendicular thereto acting through the length of the mounting holes.

The presence of at least two attachment areas ensures a stable connection of the load cell with the housing or with an intermediate bracket or a load carrier with the power transmission device. On the one hand it is a maximum distance between the fastening regions reached and on the other hand, the device is used for power transmission to torsional forces and corner load entry with an increasing number of attachment areas, especially in the case of higher-heavy load cells are relatively insensitive. The in its areal extent in the projection restricted to the respective corresponding expansion of the mounting portion slot-shaped incisions enforce only part of the width or the height of a power transmission device. They range at best, owing to production in the area of ​​the surface over the respective corresponding expansion of the fixing region beyond.

In this way, enough material remains connecting the the fixing part serving with the rest of the respective parallelogram, so that on the one hand, the voltages are largely decoupled from the sensitive part of the power transmission device, on the other hand, the apparatus for transmitting power still has a sufficiently high rigidity to the the case of an entry lateral moments on the device include this, since the entire height and the entire width of each parallelogram to intercept these moments are available. Furthermore, the surveys provide the attachment areas well-defined zones of attachment so that a uniformly symmetrical surface pressure is present.

In a preferred embodiment, the mounting portions and the slot-shaped incisions are placed either singly or in pairs in mirror symmetry with respect to a centrally running in parallel guidance parallelogram.

The slot-shaped incisions may extend obliquely or parallel or perpendicular to the corresponding mounting surface now in advantageous embodiments, in a plane.

In a preferred embodiment of the invention further rectilinear slot-shaped incisions, especially second and / or third rectilinear slot-shaped notches may be present. This can also extend obliquely to the corresponding mounting surface in a plane. In a particular embodiment, the second and / or third slot-shaped incisions in a plane aligned perpendicularly to the first slot-shaped incisions.

The force-transmitting device can now be configured such that the at least two attachment areas are laterally positioned in the region of a respective end face of a substantially block-shaped stationary parallelogram leg and / or a suitably trained deflectable parallelogram. In alternative formations which at least two attachment areas in the region of a top or a bottom of a stationary formed substantially rectangular parallelogram and / or deflectable parallelogram positioned. In further embodiments, the at least two fastening regions are divided on two mutually opposite sides of a substantially parallelepiped-shaped fixed parallelogram leg and / or deflectable parallelogram positioned.

The mounting surfaces can now be configured rectangular and / or each fastening surface is arranged point-symmetrically around the center of the bore. In particular, also be circular attachment surface. A mounting surface does not necessarily need, but may be a flat surface in a preferred embodiment.

In a particularly preferred embodiment of the invention, the apparatus for transmitting force includes a parallel guide which is formed of a single-piece solid block.

In a preferred embodiment, the entire device for power transmission is integrally formed of a material block.

The invention will be described below by way of examples, such as are shown schematically in the drawings. Show it:<dl id="dl0001"><dt>figure 1</dt><dd>an apparatus for transmitting power in a load cell, serving with one of the force reduction lever mechanism in a side view;</dd><dt>figure 2</dt><dd>a perspective view of a section of a device for power transmission with four lateral fastening regions and the first slot-shaped incisions, which images a) represent different variants to c); </dd><dt>figure 3</dt><dd>a perspective view of a section of a device for power transmission with four lateral fastening regions and first and second slot-shaped incisions, which images a) and b) represent different variants;</dd><dt>figure 4</dt><dd>a perspective view of a section of a device for power transmission with four lateral fastening regions and first, second and third slot-shaped incisions;</dd><dt>figure 5</dt><dd>a perspective view of a section of an apparatus for transmitting power with the top or bottom mounted on a parallelogram of force-transmitting device mounting areas; a) with the first slot-shaped incisions b) with the first slot-shaped incisions complementary second slit-shaped cuts in a second direction, and c) having first, second and third slot-shaped incisions;</dd><dt>figure 6</dt><dd>a perspective view of a section of an apparatus for transmitting power with top and bottom attached to the apparatus for transmitting force attachment areas, a) with the first slot-shaped incisions b) and c) different variants with first and second slot-shaped incisions;</dd><dt>figure 7</dt><dd>a perspective view of a section of a device for power transmission with four lateral fastening regions and the first angle to the mounting surfaces extending slot-shaped incisions;</dd><dt>figure 8</dt><dd>a perspective view of a section of an apparatus for transmitting power with three lateral fastening regions and first and second slot-shaped incisions, and a third cut on the underside; </dd><dt>figure 9</dt><dd>a perspective view of a section of a device for power transmission with two lateral attachment regions and first and second slot-shaped incisions.</dd></dl>

The <figref idrefs="f0001">figure 1</figref> shows a side view of a device for power transmission 1, as found in a load cell, for example, for a scale use. This power transmission device 1 has a parallel guide with an upper and a lower parallelogram 4, 5, which are each articulated to a vertically movable parallelogram 3 and a stationary parallelogram 2 on bending bearing 6 on. The power transmission device 1 has a force reduction lever serving business, which here consists of three levers 10, 11, 12th The levers 10, 11, 12 are connected by means of coupling elements 7, 8, 9 to the vertically movable parallelogram 3 and to each other and supported by means of flexure pivots 13, 14, 15 to a boom 16 of the stationary parallelogram leg second

The force-transmitting device 1 has on the end face 17 of its stationary parallelogram leg 2 on four mounting portions 20, whose mounting surfaces relative to the end surface slightly raised 23 in attaching the power transmission device 1, for example, on a housing or a housing-fixed intermediate bracket (not shown here) with this each in plant reach. Such attachment can, for example, by means of screws which are screwed into respective threaded holes of the corresponding fastening portions 20 occur. The attachment regions 20 are separately from the rest of the stationary parallelogram leg 2 and thus partially separated from the body of the power transmission device 1 by four slot-shaped incisions 21st In the figure, only one upper and one lower gap-shaped incision 21 visible. These slot-shaped incisions 21 include in their extension as the extension of the fastening surface 23 of a respective mounting portion 20, as in the<figref idrefs="f0002 f0003 f0004">Figures 2-9</figref> is detail to be seen.

At its the end face 17 opposite face 18, the vertically movable parallelogram leg 3 also has four mounting portions 30 for a not shown here load carrier or a corresponding intermediate piece on. The fastening regions 30 may be fully configured similarly to the fastening areas 20, as they are partially separated from the remainder of the vertically movable parallelogram leg 3 and hence from the body of the power transmission device 1 by upper and lower slot-shaped incisions 31st

The parallel guide is mirror-symmetrical to a symmetry plane, which extends centrally parallel to a parallelogram in the apparatus for power transmission (see also <figref idrefs="f0004">Figures 7 to 9</figref>) Configured.

<figref idrefs="f0002">figure 2</figref> a perspective view showing details of a force-transmitting device 1 in the area of ​​a parallelogram, for example, the fixed leg 2 with side attachment option of parallelogram 2, which can be connected to a non-visible here housing or housing-adapter. A total of four mounting portions 20 are arranged near a corner of the parallelogram 2, wherein each mounting portion 20 each associated with a first gap-shaped incision 21st These slot-shaped incisions 21 are produced by material removal at a distance of several millimeters from the end face 17th A preferred method for producing the slit-shaped notches 21 is the milling, but they can also be produced by erosion processes. The slot-shaped incisions 21 are the forces of moderate decoupling mounting portions 20 from the rest of the parallelogram leg 2 and therefore the body of the power transmission device. 1

A vertically movable parallelogram leg 3 can be configured in a completely analogous manner with respect to its mounting portions 30 for attachment of a scale frame or a corresponding intermediate piece. Therefore, not explicitly discussed in the following discussion to this case. The disclosure applies, however, also apply to the corresponding, also described below, embodiments of an apparatus for power transmission in the region of the vertically movable parallelogram.

The four attachment regions 20 have opposite the end face 17 on a slight elevation 25 with flat mounting surfaces 23, arrives with the force-transmitting device 1 in attachments to a housing or intermediate holder in each plant. Approximately centrally to the mounting surface 23 are threaded holes 26 can be screwed into which fastening screws. The threaded holes each ending in slit-shaped incision 21. It is understood that other fasteners such as bolts for connecting the device to the power transmission 1 to a housing or an intermediate bracket and / or for fixing the scales are used on the device for power transmission can.

The Indian <figref idrefs="f0002">figure 2a</figref>) Parallelogram shown has mounting portions 20 with elevations 25 which have a rectangular or square mounting surface 23 be flush with the edges of the leg. 2 The respectively an attachment region 20 associated first slot-shaped incisions 21 have been produced here by disc milling, which can be seen on the arcuate bottom of the slit-shaped incision 21st The slot-shaped incisions 21 extend parallel to the respective mounting surface 23 and correspond in their areal extent as that of the mounting surface 23. Due to the slot-shaped incisions formed a web 40 between the mounting portions 20 and the rest of the parallelogram leg 2, which, since it is formed relatively narrow, on the one hand caused by the mounting means force or power flow does not pass, on the other hand still has the power transmission device to the mounting areas have high strength, since both the entire height and width of the power transmission device 1 despite the decoupling means of slot-shaped incisions 21 is still here physically present ,

The <figref idrefs="f0002">figure 2b</figref>) Shows the portion of the parallelogram of 2 <figref idrefs="f0002">figure 2a</figref>) Which for the first slot-shaped incisions 22 are formed slightly wider and the ward base is flat. These slot-shaped incisions 22 were prepared by end milling.

In the <figref idrefs="f0002">2c</figref>), The elevations on 25 circular mounting surfaces 24th These have in fixing case due to their axial symmetry with respect to the bore the advantage of a more uniform power distribution to the same. It should be noted at this point that the mounting surfaces 23, 24 must be large enough so that the pressure of the compound at the attachment to a housing or to an intermediate holder is not too high and remains with respect to a flow of the material in the non-critical range.

These first slot-shaped incisions 21, 22, further slot-shaped incisions around the respective attachment areas 20 can now be mounted. The<figref idrefs="f0002">Figures 3a) and 3b</figref>) Show in the <figref idrefs="f0002">Figures 2a) and 2b</figref>) Analog representation an embodiment of an apparatus for transmitting force 1, which has at its end face 17 nor second slot-shaped incisions 27, 28 in a direction perpendicular to the first slot-shaped incisions 21, 22nd These slot-shaped incisions 27, 28 are in their expansion as well as the first slot-shaped incisions 21, 22 is limited approximately to a mounting portion 20 and are mainly used for voltage decoupling of the fastening portions 20 to each other.

The second slot-shaped incisions could in principle also penetrate the entire width of the power transmission device 1 in the region of the leg 2 in order and to strengthen as the decoupling of the mounting portions 20 with each other between the upper and lower attachment areas yet.

The <figref idrefs="f0002">figure 4</figref> shows in the <figref idrefs="f0002">Figures 2 and 3</figref> analog representation comprises an embodiment of a power transmission device 1, said third slot-shaped incisions 41 in the first and second slit-shaped recesses vertically. This third slot-shaped incisions 41 are mounted centrally between the two upper and the two lower attachment areas 20th This will be as material connections between the almost insulated fixing dice or - only still left block-shaped mounting portions 20 and the rest of the power transmission device 1 in all three dimensions narrow webs, which the force and torque decoupling comes in a special way benefit. In particular, all the mounting portions 20 are in this way with each other decoupled. Such an embodiment has a high degree of decoupling of the attachment portions 20, at the same time, however, a higher strength.

In the <figref idrefs="f0003">Figures 5a) to 5c</figref>) Is 101 to see a section of a power transmission device which can be connected, for example, at their stationary parallelogram 102 through four near the top disposed attachment areas 120 on the surface 129 above planar mounting surfaces 123 with a housing or an intermediate piece. Likewise, the attachment portions 120 may be disposed corresponding to the underside of the respective parallelogram leg 102nd In<figref idrefs="f0003">5a</figref>) Are also first slot-shaped incisions 121, 120 serve to moderate forces decoupling of fixing regions from the rest of the parallelogram 102, associated with the end face 117 facing away from attachment areas 120th The incision area corresponds approximately to the rectangular here fastening surface 123 of the mounting portions 120th

Further, and in the opposite <figref idrefs="f0003">5a</figref>) Variant shown improved decoupling of the body of the force-transmitting device 1 by the mounting portions 120, in particular from the end face facing away from 117 attachment portions 120 are second slot-shaped incisions 127, 128 approximately perpendicular to the first slot-shaped incisions approximately parallel to the mounting surfaces in the parallelogram 102 is disposed , The the end face facing away from the second slot-shaped incisions 128 are here standing configured in contact with the first slot-shaped incisions 121, but this is not mandatory. They are preferably produced by means of end milling of the outer surfaces of the parallelogram forth. The gap-shaped from the end face 117 coming fro the second notches 127 also serve mainly an improved decoupling of the end face close attachment portions 120 from the rest of the parallelogram 102nd

For this arrangement, it is possible that the second slot-shaped incisions 127 nor to deploy through the third slot-shaped incisions 141, and optionally a fourth slit-shaped incision, preferably for decoupling the mounting portions 120 with each other on the parallelogram 102 as the <figref idrefs="f0003">5c</figref>) For the case with the second slot-shaped incisions 127 and third slot-shaped incisions 141, which extend parallel to the first slot-shaped incisions, FIG.

In <figref idrefs="f0003">figure 6</figref> are three different versions of an embodiment of the power transmission device 201 with a total of four, that is, two above and two below, for example, the stationary parallelogram 202 disposed attachment areas 220 shown. The first slot-shaped incisions 221 are analogous to the slot-shaped incisions 121 in the<figref idrefs="f0003">5a</figref>) Embodiment illustrated formed, but come from above and from below, as in the <figref idrefs="f0003">6a</figref>) Is shown.

In the <figref idrefs="f0003">Fig. 6b</figref>) Is the complement of the first slot-shaped incisions 221 through the second slot-shaped incisions 227, which, like the in <figref idrefs="f0003">5b</figref>) Second slot-shaped incisions 127 shown also extend parallel to the corresponding mounting surface shown. The second slot-shaped incisions 227 serve on the one hand the uncoupling of the Befestiguhgsbereiche 220 from the rest of the parallelogram and on the other hand, the decoupling of upper and lower mounting portions 220 with each other.

The <figref idrefs="f0003">6c</figref>) Shows an embodiment in accordance with <figref idrefs="f0003">figure 6b</figref>), But the body of the power transmission device 1 has a 223 different from the expansion between the upper and lower fastening surfaces height.

For the <figref idrefs="f0003">Figure 6b) and 6c</figref>) Variants shown, the first and second slot-shaped incisions 221 also be complemented by the third slot-shaped incisions, which connect the two upper and the two lower mounting portions 220 disengage from each other.

At this point it should be mentioned that a division of the four attachment areas on the two parallelogram lying in the outer sides of the parallelogram are possible to two, wherein said first slot-shaped incisions analogous to the first slot-shaped incisions 221 in the <figref idrefs="f0003">6a</figref>) Would extend.

In the <figref idrefs="f0004">figure 7</figref> it is shown that the slot-shaped incisions need not necessarily extend parallel to the mounting surfaces. Also inclined to these surfaces extending first slot-shaped incisions 321 are conceivable; This is especially true for the not shown second and third slot-shaped incisions. However, it is to note that these oblique slot-shaped incisions are in pairs substantially mutually mirror symmetric with respect to a centrally extending in the parallel guide parallelogram, which is the plane of symmetry 360 of the parallel guide here formed. This plane of symmetry 360 is shown in the figure by broken lines. Without this requirement would be a danger that the power transmitted by the power transmission device power would have to an increasing extent also components of the desired direction of deflection of the movable Parallelogrammschenkelsalso of the direction of gravity in the case of using the power transmission device in a balance - differ. It should be noted that the extension of such oblique slot-shaped incisions 321, when projected to the direction of fastening surfaces 323, approximately corresponds to the extension of the fixing surfaces 323rd

The <figref idrefs="f0004">figure 8</figref> a perspective view showing a variant of a device for power transmission 401 with three lateral attachment regions 420, two of which are below and are arranged above the parallelogram 402nd A reverse arrangement, with two mounting areas 420 above and below is also conceivable. The lower mounting portions 420 are through the first slot-shaped incisions 422, the second slot-shaped incisions 428 and a third slot-shaped incision 441 is decoupled from the rest of the parallelogram leg 402, the upper, centrally arranged fastening portion 420 by a first 422 and a second slit-shaped notch 428, wherein all the slot-shaped incisions by means of generated end milling. Both the mounting portions 420 and the slot-shaped incisions 422, 427, 441 are mirror-symmetrical with respect to the plane of symmetry 460 of the power transmission device 402 is arranged.

<figref idrefs="f0004">figure 9</figref> shows a perspective view of a portion of a force-transmitting device 501 with two on the front face 517 superposed mounting portions 520, which are each provided with a first 522 and a second slit-shaped incision 528th Both the mounting portions 520 and the slot-shaped incisions 522, 528 are mirror-symmetrical with respect to the plane of symmetry 560 of the power transmission device 502 is located.

The inventive device for power transmission has been described in some preferred embodiments and illustrated. Based on the inventive teaching, however, more professional designs are feasible. the described measures for decoupling by slit-like incisions particular are equally to transmission components in load cells, which operate on the principle of electromagnetic force compensation or load cells, whose deformation is detected by strain gauges, as well as other, designated here unspecified load cells, apply.

LIST OF REFERENCE NUMBERS

<dl id="dl0002" compact="compact"><dt>1, 101, 201, 301, 401, 501</dt><dd>Apparatus for power transmission, power transmission device</dd><dt>2, 102, 202, 302, 402, 502</dt><dd>Fixed parallelogram, legs</dd><dt>3</dt><dd>Portable parallelogram, legs</dd><dt>4</dt><dd>Upper arm</dd><dt>5</dt><dd>lower arm</dd><dt>6</dt><dd>flexure</dd><dt>7</dt><dd>coupling element</dd><dt>8th</dt><dd>coupling element</dd><dt>9</dt><dd>coupling element</dd><dt>10</dt><dd>lever</dd><dt>11</dt><dd>lever</dd><dt>12</dt><dd>lever</dd><dt>13</dt><dd>flexure</dd><dt>14</dt><dd>flexure</dd><dt>15</dt><dd>flexure</dd><dt>16</dt><dd>boom</dd><dt>17,117,217,317,417,517</dt><dd>face</dd><dt>18</dt><dd>face</dd><dt>20, 120, 220, 320, 420, 520</dt><dd>attachment region</dd><dt>21, 121, 221, 321</dt><dd>First slot-shaped incisions</dd><dt>22, 122, 422, 522</dt><dd>First slot-shaped incisions</dd><dt>23, 123, 223, 323, 423, 523</dt><dd>mounting surface</dd><dt>24</dt><dd>Round mounting surface</dd><dt>25</dt><dd>survey</dd><dt>26</dt><dd>threaded holes</dd><dt>27, 127, 227</dt><dd>Second slot-shaped incisions</dd><dt>28, 128, 428, 528</dt><dd>Second slot-shaped incisions</dd><dt>30</dt><dd>attachment region</dd><dt>31</dt><dd>Slit-shaped incision</dd><dt>40, 140</dt><dd>web</dd><dt>41,141,441</dt><dd>Third slot-shaped incisions</dd><dt>360, 460, 560</dt><dd>plane of symmetry</dd></dl>