DE20119525U1 - Electronic scales with calibration weight configuration have a lifting mechanism based on two angled levers, which have a compact design and operate so that there is little or no friction wear on the calibration weight - Google Patents

Abstract

Electronic scales have a calibrating weight configuration, in which a calibration weight is lifted into a first weighing position where it and a calibration weight support are lowered on to the load bearing sensor of the scales and a second raised position where it is stored securely. The lifting device comprises two fixed angle levers (10, 11), the angled arms (10', 11') of which are coupled via a horizontal slider (14) and on the horizontal arms (10, 11) of which the calibration weight (9) is supported.

Description

Electronic scale with adjustment weight circuit

Description:

The invention relates to an electronic scale with an adjustment weight circuit in which an adjustment weight can be lowered by a lifting device in a first position onto an adjustment weight carrier connected to the load receptor of the weighing system and can be raised in a second position and fixed to the housing.

Electronic scales with an adjustment weight circuit of this type are generally known; a particularly space-saving embodiment of the adjustment weight circuit is described in DE 33 30 988 A1. In this embodiment, the adjustment weight is moved up or down by two lifting forks with a common axis, which together form a scissor guide. However, the geometry of this scissor guide results in an opposing horizontal movement of the support points of the adjustment weight on the two lifting forks during the upward or downward movement, and thus a frictional movement between the adjustment weight and the lifting forks. If used frequently, this frictional movement leads to the adjustment weight being worn down and thus to a loss of mass of the adjustment weight. The long-term stability of the adjustment weight as an important quality feature is thus impaired.

The object of the invention is therefore to provide an improved adjustment weight circuit for a scale of the type mentioned at the outset, which generates no or at least a greatly reduced frictional relative movement between the adjustment weight and the lifting device while requiring little space and requiring little effort.
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According to the invention, this is achieved in that the lifting device comprises two angle levers which are fixed to the housing and aligned in the same direction, the vertical lever arms of which are coupled to one another by a horizontal slider and on whose horizontal lever arms the adjusting weight rests.

Because the angle levers are aligned in the same direction, there is no relative movement of the support points for the adjustment weight, so that any frictional wear of the adjustment weight is excluded. The coupling of the two angle levers by a slider ensures a synchronous movement of the two angle levers and allows the actuation of the adjustment weight switch to be activated either by one of the angle levers or by the slider.

Advantageous embodiments emerge from the subclaims.

The invention is described below with reference to the schematic figures.

Figure 1 is a front view, partly sectioned along line I-1 in Figure 2, of the adjustment weight circuit and the weighing system in a first embodiment,
Figure 2 shows a section along the line &Pgr; - &Pgr; in Figure 1,

Figure 3 is a side view of a bearing block for supporting the angle levers and

Figure 4 is a front view, partly sectioned along line I-I in Figure 2, of the adjustment weight circuit and the weighing system in a second embodiment.

Figures 1 and 2 show a first embodiment of the calibration weight circuit and the weighing system. Figure 1 is a front view, partially sectioned along the line I - I in Figure 2, and shows the calibration weight in its raised position, Figure 2 is a vertical section along the line &Pgr; - H in Figure 1 and shows the calibration weight in its lowered position on the calibration weight carrier. One can see - especially in Figure 2 - the weighing system 1 with SW0108.doc

the load receiver 2, the links 3 and 4 and the stationary area 5, which is connected to a base plate 6 fixed to the housing. The introduction of the weight force to be measured is only indicated by the arrow 7. Weighing systems of this type are generally known and are therefore not explained in detail here; they can, for example, be equipped with strain gauges as converters or work according to the principle of electromagnetic force compensation, like the scale in the already cited DE 33 30 988 Al.

To calibrate or adjust the scale, an adjustment weight 9 with a known mass can be lowered onto an adjustment weight carrier 8 attached to the load receptor 2 and raised again after calibration or adjustment. The adjustment weight 9 is raised or lowered by two angle levers 10 and 11, which are mounted on bearing blocks 12 and 13. The bearing blocks are in turn attached to the base plate 6 or are part of the base plate 6. In Figure 1, only the rear part of the bearing blocks can be seen, in Figure 2 the front and rear parts of the bearing block 13 can be seen. The vertical lever arms 10' and 11' of the angle levers each protrude into a hole in a horizontally movable slide 14 that is fixed to the housing and are thus coupled to one another. The horizontal lever arms 10" and 11" then carry the adjusting weight 9 via a bead 10'" or 11'", whereby the bead 11'" in conjunction with a waist 9' on the adjusting weight also fixes the adjusting weight laterally (in the left/right direction in Figure 1). The slide 14 is guided fixed to the housing by projecting lugs 15 on the base plate 6.

The raising/lowering of the adjusting weight 9 is carried out by an eccentric 17, the axis 16 of which is fixed to the housing in a manner not shown. The eccentric raises or lowers the horizontal lever arm 11" of the angle lever 11. This lifting movement is transmitted as a horizontal movement of the vertical lever arm 11' via the slider 14 to the second angle lever 10 and pivots this synchronously with the first angle lever 11. The adjusting weight 9 is thereby held in a raised position in the position of the eccentric shown in Figure 1 and pressed against stops 18 fixed to the housing; in this position it does not touch the adjusting weight carrier 8. This position is the transport position and the position during normal carriage. - If the eccentric 17 is now rotated by 90° relative to the position shown in Figure 1, the adjusting weight 9 is lowered and finally rests freely on the adjusting weight carrier 8. SW0108.doc

This position is shown in Figure 2. The angle levers 10 and 11 are moved so far that the beads 10'" and 11'" no longer touch the adjustment weight. This is the position for calibration or adjustment: The adjustment weight acts as a known mass via the adjustment weight carrier 8 on the load receptor 2 of the weighing system and allows its sensitivity to be checked or adjusted. After the calibration or adjustment process has been completed, the adjustment weight is then raised again and fixed to the housing. When the adjustment weight is raised and lowered, the beads 10"' and 11'" both move on circular paths with the same radius; there is therefore no relative movement and therefore no frictional wear.

The connection of the stops 18 to the housing of the scale is not shown in the figures for the sake of clarity. The same applies to the housing-fixed bearing of the axis 16 of the eccentric 17. Both are advantageously attached to the base plate, whereby the weighing system 1 together with the adjustment weight circuit on the base plate 6 forms a complete unit and can be inserted as a unit into the housing of the scale.

For the housing-fixed mounting of the angle levers 10 and 11, these have on each Side an axle stub 10"" or 11"", which has a non-circular cross-section

as can be seen in Figure 1. To mount the angle levers, this in a direction almost 90° clockwise from the direction shown in Figure 1 rotated position into the slots 12' or 13' from above and then rotated by almost 90° into the position shown in Figure 1. In this position, the

Axle stub 10" or 11" in the circular extension 12" or 13",

as can be seen in the detailed view of the bearing block 12 or 13 in Figure 3, This design allows for a very simple and quick installation the angle lever. The installation of the slider 14 is also very simple: It must only be inserted into the base plate from the side before inserting the angle lever be inserted and is secured after inserting the angle levers by their vertical arms 10' and 11' held.

A second design of the adjustment weight circuit is shown in Figure 4. The representation in Figure 4 corresponds to the representation in Figure 1, the same parts as in Figure 1 are designated with the same reference numbers and are not explained again. The vertical section in Figure 2 applies to both designs. In the design according to Figure 4, the drive of the SW0108.doc

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Lifting movement for the adjustment weight on the slide 24: A fork-shaped actuating part 23 is connected to the slide 24; a pin 21 extends into the vertical slot 22 of this actuating part, which is arranged eccentrically on a disk 20 that is mounted on an axis 26 fixed to the housing. When the disk 20 is rotated by a motor, the slide 24 is displaced horizontally by this arrangement; the slide transfers this displacement to the two angle levers 10 and 11 and thereby raises or lowers the adjustment weight 9 in the manner already described. The remaining parts correspond to the parts of the first embodiment according to Figure 1.

In both described embodiments, the slider 14 or 24 is fixed to the housing and the force is transmitted between the slider and the angle levers 10 and 11 through holes in the slider into which the vertical lever arms 10' or 11' protrude. This design enables particularly simple assembly. However, it is also possible to couple the slider to the vertical lever arms of the angle levers using axes. This eliminates the need for the slider to be fixed to the housing, but two axes must be installed and fixed.

SW0108.doc

Claims (7)

1. Electronic scale with an adjustment weight circuit, in which an adjustment weight can be lowered by a lifting device in a first position onto an adjustment weight carrier connected to the load receptor of the weighing system and can be raised in a second position and fixed to the housing, characterized in that the lifting device comprises two angle levers ( 10 , 11 ) which are mounted on the housing and aligned in the same direction, the vertical lever arms ( 10 ', 11 ') of which are coupled to one another by a horizontal slide ( 14 , 24 ) and on whose horizontal lever arms ( 10 ", 11 ") the adjustment weight ( 9 ) rests. 2. Electronic scale with an adjustment weight circuit according to claim 1, characterized in that the slide ( 14 , 24 ) is fixed to the housing and the vertical lever arms ( 10 ', 11 ') of the angle levers ( 10 , 11 ) project into holes in the slide ( 14 , 24 ). 3. Electronic scale with an adjustment weight circuit according to one of claims 1 or 2, characterized in that an angle lever ( 9 ) can be pivoted by an eccentric ( 17 ) seated on a motor-driven shaft ( 16 ). 4. Electronic scale with an adjustment weight circuit according to one of claims 1 or 2, characterized in that the slide ( 24 ) is displaceable by an eccentrically mounted pin ( 21 ) sitting on a motor-driven shaft ( 26 ). 5. Electronic scale with an adjustment weight circuit according to one of claims 2 to 4, characterized in that the slide ( 14 , 24 ) is guided on a base plate ( 6 ) and that the weighing sensor ( 1 ) is also fastened to this base plate ( 6 ) and the motor-driven shaft ( 16 , 26 ) is mounted. 6. Electronic scale with an adjustment weight circuit according to one of claims 1 to 5, characterized in that the angle levers ( 10 , 11 ) have two axle stubs ( 10 "", 11 "") with a non-circular cross-section for mounting, that the housing-fixed bearing blocks ( 12 , 13 ) each have a vertical slot ( 12 ', 13 ') which ends in a circular widening ( 12 ", 13 "), and that the width of the slot ( 12 ', 13 ') is selected such that the associated axle stub ( 10 "", 11 "") fits through the slot ( 12 ', 13 ') in a first angular position, while in a second angular position rotated by approximately 90° with respect to the first it is caught in the circular widening ( 12 ", 13 "). 7. Electronic scale with an adjustment weight circuit according to one of claims 1 to 6, characterized in that the two angle levers ( 10 , 11 ) are of identical design.