Abstract:
A weighing cell module with a force-transfer mechanism that includes a parallel-guiding linkage with a vertically movable parallelogram leg and a spatially fixed parallelogram leg, is equipped with a mounting area for a first weighing-pan support device with a single-point connection of a weighing pan, as well as with a mounting area for a second weighing-pan support device with a multiple-point connection, particularly a four-point connection, of a weighing pan, wherein the first and the second mounting area are each connected to the force-transfer mechanism. As a result, the weighing cell module can be used to manufacture different types of balances in a design family of balances, where each different type within the family is designed for a different maximum load.

Description:
BACKGROUND OF THE INVENTION 
   The invention relates to a weighing cell, more specifically a weighing cell module with a force-transfer mechanism that includes a parallel-guiding linkage with a vertically movable parallelogram leg and a spatially fixed parallelogram leg. 
   In a weighing cell as the core element of a balance, the force-transfer mechanism—based on its design for a given maximum load and based on the accuracy that it is capable of achieving—essentially determines the range of applications that a balance can be used for. 
   Commercially available balances are often structured in so-called families or series of balance models, where the balances within a model family have a similar appearance and are identified by similar model designations. A family of balances is often the result of either a single development project or of a group of mutually connected projects. 
   Balances of the existing state of the art have the problem that within a model family, the respective weighing cells for different maximum loads and different measurement resolutions can differ strongly from each other in regard to their overall design and their subassemblies. Thus, a large number of variations exists among the subassemblies, which leads to high production and inventory costs. 
   In particular, the different models within a family of balance models also frequently differ in regard to the size of the weighing pan and the way in which the weighing pan is coupled to the weighing cell. According to a known concept that has proven useful for balances of higher load capacities, the weighing pan which in this case normally needs to be of a larger size, or a weighing-pan support if applicable, is coupled at several (in most cases four) points to the load-receiving part of the weighing cell, i.e., the vertically movable parallelogram leg of the force-transfer mechanism, in order to avoid detrimental effects from eccentrically positioned weighing loads. In low-capacity balances on the other hand, which in most cases have a small weighing pan, the preferred arrangement is to couple the weighing pan to the load-receiving part through a so-called single-point connection, for example through a conical support serving as a seat for the weighing pan. 
   The known state of the art includes balances in which individual components are already configured in a way that allows them to be adapted to different maximum loads in a relatively economical way. 
   For example, a balance that is disclosed in EP 0 573 806 A1 has a measuring cell that is connected to a U-shaped intermediate support frame through a form-fitting and force-transmitting connection. The measuring cell is arranged between the U-legs of the intermediate support frame and fastened to the base section of the U-frame. The respective contact surfaces on the intermediate support frame and on the measuring cell are finished within very narrow tolerances, so that no assembly stresses are introduced into the measuring cell when the support frame and the measuring cell are bolted together. Thus, the measuring cell can be adjusted together with the intermediate support frame prior to installation in a balance housing, and the measuring cell and support frame can be installed into a housing as a unit. The U-shaped intermediate support frame is designed to receive measuring cells of different widths. 
   An overload-protection system for a precision balance described in DE 295 14 793 U1 has a secondary parallel-guiding linkage with upper and lower guide arms, where the ends of the arms that face towards the weighing pan are joined to a connecting leg and the ends that face away from the weighing pan are joined to the load receiver, so that the guide arms, the connecting leg, and the load receiver are tied together in the manner of a parallelogram linkage. The overload protection system includes at least one pre-tensioned spring that keeps the weighing pan and the load receiver rigidly coupled to each other within the weighing range of the balance. The spring is positioned between the upper guide arm and a seating plate that is rigidly connected to the load receiver. The connecting leg passes with lateral clearance through the seating plate. With this design concept it is possible to arrange the overload protection system primarily in a lateral position at the front end of the measuring cell so that it takes up little space. 
   In addition, a receiving device for a calibration weight can be fastened to or integrated in the guide plates that contain the flexure pivots and are connected by two guide bolts, or it can be fastened to or integrated in the seating plate of the secondary parallel-guiding linkage. Thus, the overload protection system can be preassembled outside the balance and adjusted to the maximum load capacity of the balance. This subassembly is connected to the measuring cell through a small number of screws. The device can be adapted to different load ranges by using a spring with a different spring constant. 
   However, although the devices disclosed in the prior art are designed to use some of the same individual components in more than one balance model, there is still a relatively large diversity in respect to the overall number of subassemblies. Particularly if balances have to be equipped with weighing pans of different sizes, e.g., small or intermediate-sized or large weighing pans, it is necessary to make accommodations in the design for a stable coupling of the differently sized pans to the weighing cell. Thus, weighing pans exceeding a certain size can no longer be held by means of a cone with a single-point connection to the weighing pan, because the effects of an eccentric position of the weighing load could have too large an influence on the weighing result. An overload device, too, has to meet different requirements depending on the size of the weighing pan. The influence of laterally directed torques which can have an effect on the force-transfer mechanism and can ultimately cause its destruction increases with larger sizes of weighing pans. The objective is to intercept these laterally directed torques. 
   SUMMARY 
   Consequently, the task set for the present invention is to harmonize the designs of the components of a balance in such a way that a large diversity of different types of balances within one family of balance models can be made with as few different subassemblies as possible. 
   The solution to this task is provided through an arrangement with the characterizing features of claim  1 . A weighing cell module with a force-transfer mechanism that includes a parallel-guiding linkage with a vertically movable parallelogram leg and a spatially fixed parallelogram leg has a mounting area for a first weighing-pan support device with a single-point connection to the weighing pan as well as a mounting area for a second weighing-pan support device with a multiple-point connection, in particular a four-point connection, to the weighing pan, wherein each of the respective mounting areas for the first and second weighing-pan supports is connected to the force-transfer mechanism. With this design concept, the weighing cell module can be used to manufacture different types of balances in a model family, wherein the different types are designed primarily for different maximum load capacities. 
   In a family of balance models in which the different types are often distinguished from each other by the size of the weighing pan and by the way in which the weighing pan is coupled to the weighing cell, in particular whether the weighing pan is coupled to the vertically movable parallelogram leg of the force-transfer mechanism at several (in most cases four) points or at a single point, e.g., through a conical support post, the weighing cell module according to the invention makes it possible to connect either type of weighing pan and thus offers a high degree of flexibility. Consequently, a large diversity of different models can be produced within a single design family of balances, while at the same time the number of subassemblies or assembly modules is kept low. 
   A weighing cell module designed according to the invention is preferably preassembled and adjusted outside of the balance, so that weighing cell modules of a given type become interchangeable for a specified balance model. The concept of a separately adjustable weighing cell module is of particular advantage in service situations, for example if the weighing cell module has to be exchanged outside of the manufacturing facility. 
   In a particular embodiment of a weighing cell module, the mounting area for the first weighing-pan support device with a single-point connection of the weighing pan as well as the mounting area for the second weighing-pan support device with a multiple-point connection, in particular a four-point connection, of the weighing pan are connected to the force-transfer mechanism by means of an intermediate part. Preferably, if the weighing cell module has an overload protection device, the intermediate part is a component of the overload protection device. 
   In a particularly preferred configuration, the overload protection device has a secondary parallel-guiding linkage with upper and lower guide arms, wherein one end of each guide arm is connected to the vertically movable parallelogram leg of the force-transfer mechanism and the opposite end is connected to at least one connecting member, so that the guide arms, the connecting member, and the vertically movable parallelogram leg of the force-transfer mechanism are tied together in the manner of a parallelogram linkage. The respective mounting areas for the first weighing-pan support device as well as for the second weighing-pan support device are arranged on the connecting member of the secondary parallel-guiding linkage. 
   In a particularly advantageous embodiment, the overload protection device includes a pre-tensioned spring that keeps the weighing pan and the vertically movable parallelogram leg rigidly coupled to each other as long as the load on the balance is within the load range. Specifically, the pre-tensioned spring is a helix spring that is adapted to the maximum load specified for the weighing cell module. 
   In a preferred further developed embodiment of the weighing cell module, the overload protection device includes first and second displacement-limiting stop means that are spatially separated from each other. The second displacement-limiting stop means are configured in such a way that when a weighing cell module is used for the multiple-point connection of the weighing pan, the second displacement-limiting stop means become effective in addition to the first displacement-limiting stop means. 
   Another embodiment has a chassis body through which the stationary parallelogram leg of the force-transfer mechanism can be rigidly connected to a housing. The chassis body, which is of a particular configuration with a U-shaped profile, is designed to accommodate force-transfer mechanisms of different sizes which are specified for different maximum loads. Furthermore, the displacement-limiting stop means of the overload protection device include at least one displacement-limiting stop arranged on the chassis body. 
   With this design concept, the weighing cell module is intrinsically protected, i.e., the protection does not depend on displacement-limiting overload-protection stops of the kind that are attached to a housing, in which case a special adaptation of the housing to the weighing cell module would be required, as the clearance gaps of the displacement-limiting stops have to be set with the most exacting precision. 
   The mounting area for the second weighing-pan support device with several (specifically four) connecting points to a weighing pan is arranged either laterally on both sides of the force-transfer mechanism, or at the intermediate part (if the design includes an intermediate part), in particular at the secondary parallelogram mechanism of the overload protection device. The mounting area for the second weighing-pan support device has ribbed surface portions, and the second weighing-pan support has two support beams, each of which likewise has a ribbed surface portion. Through the mutual engagement of the respective ribbed surface portions the support beams can be attached in a form-fitting and force-transmitting connection to the mounting area. 
   If even larger weighing pans are used with an arrangement of multiple support points, the two support beams can be joined by transverse connectors to form a frame on which the support points for the weighing pan are located. It should be mentioned at this point that the points of attachment of a weighing pan to a balance should be paced as close as possible to the border of the weighing pan in order to minimize the harmful effects of eccentrically positioned loads. 
   In a particularly preferred embodiment of a weighing cell module, the second displacement-limiting stop means include a displacement-limiting bolt which can be attached to the support beam or to the frame and which, in the assembled condition of the weighing cell module, is located between an upper second displacement-limiting stop and a lower second displacement-limiting stop, which are both arranged on the chassis body. 
   The weighing cell module according to the invention not only minimizes the number of different subassemblies for the connection of the weighing pan and for the overload protection device but is also designed with the aim of reducing further components of the balance, for example the calibration system, to a small number of variable elements in each subassembly. 
   The latter objective is attained in the case of the calibration system through an arrangement with a calibration device that includes a calibration weight receiver, a calibration weight, and a weight-handling device to apply and remove the calibration weight, wherein the calibration weight receiver is connected to the force-transfer mechanism and the calibration weight-handling device is connected to the chassis body. This configuration of the calibration weight-handling device—i.e., the mechanical and electrical components required to lower the weight onto the calibration weight receiver for the calibration measurement and to subsequently raise the calibration weight again—deviates from state-of-the-art arrangements as disclosed, e.g., in EP 0 955 530 A1, where the calibration weight-handling device is connected exclusively to the housing. 
   To produce a balance that is suitable for the measurement of larger loads, the only modification to be made in the weighing cell module with regard to the calibration device consists of adapting the calibration weight to the maximum load specified for the weighing cell module. 
   In a specific embodiment of the weighing cell module, the parallel-guiding linkage of the force-transfer mechanism is made as a single piece from a monolithic block of material. In an alternative design, the entire force-transfer mechanism is made monolithically of a single block of material. The force-transfer mechanism operates in particular according to the principle of electromagnetic force compensation. 
   The weighing cell module forms an independent unit which can be completed or expanded in different ways in order to generate a model family of balances in which the number of subassemblies is kept small, but which nevertheless offers the diversity required by the user for example in regard to maximum load, resolution, calibration capabilities, and size of the weighing pan. 
   Beyond the force-transfer mechanism itself, it is a preferred concept that specifically those parts or subassemblies with a high manufacturing cost in a weighing cell module according to the invention can be used for all of the individual models in a design family of balances, for example the secondary parallel-guiding linkage of the overload-protection device, the calibration weight-handling device, the chassis body, as well as the weighing pan support devices. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the following, the invention is further described through examples that are illustrated schematically in the drawings, wherein: 
       FIG. 1  illustrates a weighing cell module equipped with a support device for a single-point connection of a small weighing pan, in a three-dimensional representation; 
       FIG. 2  illustrates a chassis body in a three-dimensional representation; 
       FIG. 3  illustrates a secondary parallel-guiding linkage of an overload protection mechanism in the form of a secondary parallelogram, shown in a three-dimensional representation; 
       FIG. 4  illustrates a weighing cell module with added support beams for a four-point connection of an intermediate-sized weighing pan, in a three-dimensional representation; 
       FIG. 5  shows a partially disassembled weighing cell module in a three-dimensional representation, wherein the weighing cell module of  FIG. 1  has been expanded with a frame and thereby configured for a four-point connection of a large weighing pan; with  FIG. 5   a  representing a view directed at an oblique angle from above and  FIG. 5   b  representing a view directed at an oblique angle from below; 
       FIG. 6  shows the weighing cell module of  FIG. 5  in the assembled state, in a perspective representation; 
       FIG. 7  illustrates a weighing cell module according to a further embodiment which is expanded with support beams that can be fastened directly to the force-transfer mechanism, shown taken apart in a schematic representation. 
   

   DETAILED DESCRIPTION 
     FIG. 1  gives a perspective view of parts of a weighing cell that are assembled to form a module which in the following will be referred to as weighing cell module and identified by the reference symbol  1 . The preferred working principle for the weighing cell module  1  is electromagnetic force compensation. In addition to electrical and electronic components, the weighing cell module  1  includes a force-transfer mechanism  2  with a parallel-guiding linkage in which a stationary parallelogram leg  3  and a movable parallelogram leg  4  are connected by a pair of guide arms  5  (with only one guide arm  5  being visible in the drawing). The force-transfer mechanism is an integral part of a monolithic material block wherein the essential parts, i.e., the parallelogram, the lever arrangement, the coupling elements and the fulcrum supports (not visible in drawing), are separated from each other by material-free areas in the form of thin linear cuts  6  that traverse the material block in the direction perpendicular to the plane of rotation of the at least one force-reduction lever. A force-transfer mechanism of this kind belongs to the known state of the art and is disclosed in detail in EP 0 518 202 A1. The stationary parallelogram leg  3  of the force-transfer mechanism  2  is connected through a form-fitting and force-transmitting attachment to the base section  12  between the U-legs  11  of a U-shaped chassis body  10 . For the purpose of this connection, the connecting contact surfaces on the force-transfer mechanism  2  as well as on the chassis body  10  are finished flat and within narrow tolerances. 
   A secondary parallel-guiding linkage  20  of an overload protection device is solidly connected to the movable parallelogram leg  4  of the force-transfer mechanism  2 . The secondary parallel-guiding linkage  20  is folded back into itself, which means that its guide arms  21  extend first into the space outside of the force-transfer mechanism  2  before splitting into two parts that continue in the reverse direction along the sides of the force-transfer mechanism  2  to locations about laterally adjacent to the movable parallelogram leg  4 , where the upper and lower guide arms  21  are connected on each side by a guide bolt  22 . This secondary parallelogram linkage  20  can be seen in  FIG. 3  and will be discussed in further detail below in the context of  FIG. 3 . 
   A calibration weight-handling device  30  is attached directly to the chassis body  10  at the opposite end of the weighing cell module from where the force-transfer mechanism  2  is fastened to the chassis body  10 . A calibration weight receiver  35  which holds the calibration weight  36  during the calibration measurement is connected to a lever extension  37  that is attached directly to the force-transfer mechanism  2 , particularly to a lever of the force-transfer mechanism  2 . A calibration device of this kind belongs to the known state of the art as disclosed in EP 0 955 530 A1. However, the calibration weight-handling device according to this reference is not connected to a chassis body but to the balance housing. The calibration weight-handling device  30  includes an electric motor which is arranged in a motor housing  31  and serves to raise and lower the calibration weight  36  onto the calibration weight receiver  35 . 
   The reduced-scale illustrations a) and b) in the upper right-hand part of  FIG. 1  schematically represent balances  7  and  7 ′ that are equipped with a weighing cell module  1  according to the foregoing description. The balance  7  has a round weighing pan  8 , and the balance  7 ′ has a rectangular weighing pan  8 ′, both of which are designed for a single-point connection of the weighing pan. 
   The leg connecting the folded-back ends of the guide arms  21  of the secondary parallel-guiding linkage  20  of the overload protection device carries a cone  19  as a seat for the weighing pan  8 ,  8 ′. The weighing pan  8 ,  8 ′ can be set either directly or in certain cases by means of a weighing pan support (not shown in the drawing) on the cone  19 , an arrangement that is referred to as single-point load introduction. 
   A weighing cell module  1  as illustrated in  FIG. 1  and described in the foregoing paragraphs is used with preference in balances for a load range up to about one kilogram, in which case the force-transfer mechanism  2  as well as the calibration weight  36  and the springs of the overload protection device (which will be further described in the context of  FIG. 3 ) are optimized as subassemblies or parts for use in this load range. 
     FIG. 2  illustrates the U-shaped chassis body  10  in a three-dimensional representation. The chassis body  10 , which is preferably made as an integrally cast part, consists of a base section  12  and two U-legs  11 . At the far end from the base section  12 , the U-legs  11  continue into outwardly offset extensions  13  with tapped holes  18  where the calibration weight-handling device  30  (see  FIG. 1 ) can be fastened with screws. The ledge  17  at the other end of the extension  13  functions as a first displacement-limiting stop in conjunction with the overload protection device  20 . The mounting surface  16  on the inside of the U-shaped chassis body is finished to narrow tolerances, as mentioned above, to provide a precisely fitting contact with the end surface of the force-transfer mechanism  2 , which is likewise finished to correspondingly small tolerances. 
   The chassis body  10  has tapped holes at its underside (not visible in the drawing) which serve to fasten the chassis body  10  to the base plate (likewise invisible) of a balance housing  9 ,  9 ′ (see reduced-scale illustrations a) and b) in  FIG. 1 ). The reference symbols  14  and  15  identify, respectively, upper and lower displacement-limiting stops for the overload protection device which will be explained in more detail below in the context of  FIGS. 5   a  and  5   b.    
     FIG. 3  illustrates, likewise in a perspective view, a secondary parallel-guiding linkage  20  of the overload protection device. An upper and lower guide arm, both identified by reference symbols  21 , have respective fastening areas  26  through which the secondary parallel-guiding linkage  20  can be fastened to the top and bottom of the movable parallelogram leg  4  of the force-transfer mechanism, preferably by means of screws. Because of their folded-back configuration, the guide arms  21  have turnaround areas  27  at the far ends from the fastening connection. From the turnaround areas  27 , each guide arm is divided into two parts that extend along the outsides of the centrally positioned fastening areas  26 . Near the turnaround areas  27 , the sections of the guide arms  21  are provided with flexing joints  28 . Further flexing joints  28  are located at the transitions from the guide arms  21  to a load-receiving portion  29  of the secondary parallel-guiding linkage  20 . In the load-receiving portion  29 , the upper and lower guide arms  21  are connected to each other, forming a kind of cage, and they are further in contact with each other through two guide bolts  22  (only one of which is visible) that are arranged inside the cage. A frusto-conical support  19  (also referred to as support cone  19 ) is installed at the top of the load-receiving portion  29  of the secondary parallel-guiding linkage  21  as a seat for a weighing pan or a weighing-pan support. In case of an overload, the load-receiving portion  29  yields at the flexing joints  28  and moves downward in relation to the fastening areas  26  that are connected to the force-transfer mechanism  2 . 
   Inside the cage, opposite the fastening location of the cone  19 , the secondary parallel-guiding linkage has a seating plate  25  which is traversed with contact-free clearance by the two guide bolts  22 . The seating plate  25  is rigidly connected to the vertically movable parallelogram leg  4  of the force-transfer mechanism  2 . Each of the guide bolts  22  is enveloped by a helix spring  23 , which is only symbolically indicated in the drawing. The helix springs  23  are pre-tensioned to bear against the seating plate  25 . Under normal operating conditions, the seating plate  25  and the load-receiving portion  29  that forms the cage are pushed into contact with each other, i.e., the secondary parallel-guiding mechanism behaves like a rigid body. However, when an excessive load is applied to the load-receiving portion  29 , the latter is deflected downward in relation to the seating plate  25 , compressing the two springs  23  and coming to rest on the ledges  17  of the chassis body  10  (see  FIG. 2 ). Each of the two lugs  24  with openings serves to hold a displacement-limiting bolt (see  FIGS. 5   a  and  5   b ). 
   The outward-facing surfaces  39  on both sides of the load-receiving portion  29  are ribbed and provided with two tapped holes  38 . This feature is provided for the attachment of parts that serve to expand the weighing cell module  1  for use in a higher load range, which will be explained below in further detail. 
     FIG. 4  illustrates the weighing cell module  1  with an adaptation for an intermediate-sized, preferably rectangular weighing pan  8 ″ supported at four points, with a reduced-scale view a) showing the overall configuration of a balance  7 ″ with the weighing pan  8 ″. The adaptation consisted only of removing the support cone  19  and adding a support beam  40  on each side of the secondary parallel-guiding linkage  20 . The topsides of the support beams  40  each carry a tub  41  that serves to catch water which may drip into the balance, especially when the balance is placed in an environment of high humidity. Support bolts  42  for the weighing pan are arranged on the support beams  40 , standing out at both ends of each tub  41 , with fastening nuts  43  on the support bolts  42  holding the tubs  41  in place on the support beams  40 . 
   Accordingly, the secondary parallel-guiding linkage  20  of the overload protection device serves as an intermediate part in the connection of a weighing pan to the vertically movable parallelogram leg  4  of the force-transfer mechanism  2 , regardless of whether the load is applied through a single-point connection of the weighing pan by means of the support cone  19  or a four-point connection by means of the support beams  40  and the support bolts  42 . 
     FIG. 4  shows the mounting area  32  for the support cone  19  which has been removed here, as well as the tapped hole  33  where the support cone  19  is fastened to the load-receiving portion  29 . 
   In the process of manufacturing the weighing cell module, only a small number of subassemblies or parts have to be installed additionally or alternatively—for example the force-transfer mechanism—in order to produce a weighing cell module  1  for a balance with an intermediate-sized weighing pan  8 ″ with four-point connection instead of a weighing cell module  1  for a balance with a small weighing pan  8 ,  8 ′ with single-point connection. Since intermediate-sized weighing pans  8 ″ are normally used in balances  7 ″ that are designed for a higher load range, a weighing cell module  1  with an intermediate-sized weighing pan  8 ″ is preferably equipped with a force-transfer mechanism  2  that is designed for commensurately higher loads, further with an overload protection device  20  that becomes effective at higher overloads (which only requires a pair of helix springs with a stiffer spring constant), and also with a larger calibration weight  36 ′. All other subassemblies of the weighing cell module  1 , i.e., the chassis body  10 , the secondary parallel-guiding linkage  20 , and the calibration weight-handling device  30  are the same as for a weighing cell module  1  that is used for balances  7 ,  7 ′ in the low-capacity load range. 
     FIGS. 5   a  and  5   b  show a perspective view of a weighing cell module  1  that is partially taken apart, with  FIG. 5   a  representing a view directed at an oblique angle from above and  FIG. 5   b  representing a view directed at an oblique angle from below. While the tubs  41  of  FIG. 4  have been omitted,  FIGS. 5   a  and  5   b  illustrate the same weighing cell module  1  as in  FIG. 4  with the addition of transverse connectors  45  which, in conjunction with the support beams  40 , form a frame  46 . A frame  46  of this kind, which is formed by bolting the transverse connectors  45  to the support beams  40  and which contains four support bolts  47  attached to the ends of the transverse connectors  45 , can again be used for a four-point support of a large weighing pan, i.e., a weighing pan with a larger load-receiving surface than the weighing pan of the expanded weighing cell module of  FIG. 4 . 
   As can further be seen in  FIG. 5   a , the support beams  40  have a connecting area  48  with a ribbed surface analogous to the ribbed structure of the outward-facing surface  39  of the load-receiving portion  29  of the secondary parallel-guiding linkage  20 , so that a form-fitting and force-transmitting connection is formed by the mutual engagement of the two ribbed structures, whereby the support beams  40  are joined without play to the overload protection device  20 . The support beams  40  can thus be held in a defined, unchangeable position by means of the screws  52  that are turned tightly into the tapped holes  38 . 
     FIG. 5   a  as well as  FIG. 5   b  show first displacement-limiting stop means  50  and second displacement-limiting stop means  60  of the overload protection device  20 . The first displacement-limiting stop means  50  are constituted by a screw  51  which is turned into the hole of the lug  24  where it is secured in a stable position and by the ledge  17  which stops the screw  51  in the case of an overload, i.e., if the secondary parallel-guiding linkage is deflected downward in relation to the movable parallelogram leg  4  of the force-transmitting device  2 . The first displacement-limiting stop means  50  are provided for a weighing cell module  1  independent of whether it is used in balances with a small, intermediate or large weighing pan. The first displacement-limiting stop means  50  serve primarily to absorb overloads that are directed vertically downward at the force-transfer mechanism  2 . 
   The second displacement-limiting stop means  60  are provided only for the use of a weighing cell module  1  in balances with intermediate or large-sized weighing pans. The second displacement-limiting stop means  60  include bolts  61  with fastening nuts  62  which are installed in the tapped holes  63  in both of the support beams  40 . In the assembled condition, the protruding end of the bolt  61  is positioned between the upper second displacement-limiting stop  14  and the lower second displacement-limiting stop  15  and becomes effective in the case of upward-directed as well as downward-directed overloads. The second displacement-limiting stop means act in particular as a safety device against torques caused by eccentrically introduced forces, in particular torques that tend to force the weighing pan into a tilted position. 
   As a result, an overload device  20  has been provided with displacement-limiting stop means  50 ,  60  which in the case of overloads become effective in a hierarchical sequence. 
   The first and second displacement-limiting stop means  50 ,  60  are adjustable in regard to how large a deflection they will allow in the secondary parallel-guiding linkage in case of an overload. This adjustment is performed for the first displacement-limiting stop means  50  by turning the screw  51  to set its distance from the ledge  17  and in the case of the second displacement-limiting stop means  60  by turning the bolt  61  which is designed as an eccentric so that the respective gaps from the eccentric bolt  61  to the upper and lower second displacement-limiting stops  14  and  15  can be made larger or smaller depending on the position in which the bolt  61  is locked tight in the tapped hole  63 . As a rule, this process of setting the overload protection device  20  is performed only once, i.e., in the course of adjusting the weighing cell module  1  prior to its installation in a balance housing  9 ,  9 ′,  9 ″,  9 ′, 
   As an additional benefit, by deviating from the state of the art in the configuration of the displacement-limiting stop means  50 ,  60 , i.e., by integrating them in the weighing cell module  1  rather than attaching them to the housing, the tolerances of the clearance gaps in the displacement-limiting stop means can be controlled better, so that the reproducibility of the displacement-limiting effect is improved. 
     FIG. 6  shows the weighing cell module of  FIGS. 5   a  and  5   b  in the assembled state, viewed from above at an oblique angle. This representation shows clearly how the support beams  40  and the transverse connectors  45  are joined together to form the frame  46 . The support bolts  47  are arranged to support a large rectangular weighing pan  8 ′ as closely to the corners as possible. The reduced-scale drawing a) in  FIG. 6  represents a corresponding balance  7 ′ with a large rectangular weighing pan  8 ′ and a housing  9 ′. 
   A weighing cell module  1  according to  FIG. 6  is adjusted in the same manner as the weighing cell modules shown in  FIGS. 1 and 4 , i.e., the adjustment takes place outside the balance, and the weighing cell is installed as a completed assembly module in a balance  7 ′. The adjustments of the weighing cell module outside of the balance include in particular a temperature-compensation adjustment, so that the weighing data and weighing parameters of a balance that has been equipped with a weighing module  1  according to the foregoing description are largely unaffected by temperature effects. 
   The invention has been described through an example of a weighing cell module with a U-shaped chassis body. However, based on what the invention teaches it is also conceivable to use other shapes for the chassis body, for example a connecting plate or a connecting base, to mount the force-transfer mechanism in a housing. As a principle, the additional subassemblies of the weighing cell module, such as for example a calibration weight-handling device or an overload protection device, are attached either to the force-transfer mechanism or to the chassis body. It is self-evident that other calibration weight arrangements or other embodiments of an overload protection device that are suitable for integration in a weighing cell module according to the foregoing description are also encompassed by the inventive concept. In particular, the force-transfer mechanism is not meant to be limited exclusively to devices based on the principle of electromagnetic force compensation. Within the realm of the invention it is also conceivable to use a force-transfer mechanism in which strain gauges are used as sensors, as well as other force-transfer mechanisms that are not specified in detail herein. 
     FIG. 7  demonstrates in a strongly generalized schematic view that there is no absolute need for a weighing cell module to be equipped with an overload protection device or a calibration device. A weighing cell module of this kind is used for example in a simple balance with relatively modest accuracy requirements. This configuration of a weighing cell module  101  offers the choice that either a support cone  119  for a single-point connection of the weighing pan or two support beams  140  with support bolts  142  can be fastened directly to the force-transfer mechanism  102 . In the embodiment of  FIG. 7 , a tapped hole  69  for anchoring the support cone  119  is arranged in the top surface  75  of the vertically movable parallelogram leg  104 , and a fastening area  70  with a ribbed outward-facing surface  71  and two tapped holes  72  for the attachment of a support beam  140  is provided on each side of the movable parallelogram leg  104 . The support beams  140  are likewise provided with a ribbed surface area  73  on the side that faces the force-transfer mechanism. The stationary parallelogram leg  103  of the force-transfer mechanism  102  is extended at the bottom into a stepped-off fastening portion  74  that serves to install the force-transfer mechanism  102  in a balance housing or on the base plate of a balance housing. 
   LIST OF REFERENCE SYMBOLS 
   
       
       
         
             1 ,  101  weighing cell module 
             2 ,  102  force-transfer mechanism 
             3 ,  103  stationary parallelogram leg 
             4 ,  104  vertically movable parallelogram leg 
             5  guide arm of parallelogram linkage 
             6  thin linear cuts 
             7 ,  7 ′,  7 ″,  7 ′ balance 
             8 ,  8 ′,  8 ″,  8 ′ weighing pan 
             9 ,  9 ′,  9 ″,  9 ′ balance housing 
             10  U-shaped chassis body 
             11  U-leg 
             12  base section of  10   
             13  extension of U-leg 
             14  upper second displacement-limiting stop 
             15  lower second displacement-limiting stop 
             16  mounting surface 
             17  ledge of first displacement-limiting stop 
             18  tapped holes 
             19 ,  119  support cone 
             20  secondary parallel-guiding linkage 
             21  guide arm of secondary parallel-guiding linkage 
             22  guide bolt 
             23  spring, helix spring 
             24  lug 
             25  seating plate 
             26  fastening area 
             27  turnaround area 
             28  flexing joint 
             29  load-receiving portion 
             30  calibration weight-handling device 
             31  motor housing 
             32  mounting area for support cone 
             33  tapped hole 
             35  calibration weight receiver 
             36 ,  36 ′ calibration weight 
             37  lever extension 
             38  tapped hole 
             39  outward-facing surface 
             40 ,  140  support beam 
             41  tub 
             42 ,  142  support bolt 
             43  fastening nut 
             45  transverse connector 
             46  frame 
             47  support bolt 
             48  connecting area 
             50  first displacement-limiting stop means 
             51  screw 
             52  screw 
             60  second displacement-limiting stop means 
             61  bolt 
             62  fastening nut 
             63  tapped hole 
             69  tapped hole 
             70  fastening area 
             71  ribbed outward-facing surface 
             72  tapped holes 
             73  ribbed surface area 
             74  stepped-off fastening portion 
             75  top surface of vertically movable parallelogram leg  104