Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
  • G01L1/00—Measuring force or stress, in general
  • G01L1/20—Measuring force or stress, in general by measuring variations in ohmic resistance of solid materials or of electrically-conductive fluids; by making use of electrokinetic cells, i.e. liquid-containing cells wherein an electrical potential is produced or varied upon the application of stress
  • G01L1/22—Measuring force or stress, in general by measuring variations in ohmic resistance of solid materials or of electrically-conductive fluids; by making use of electrokinetic cells, i.e. liquid-containing cells wherein an electrical potential is produced or varied upon the application of stress using resistance strain gauges
  • G01L1/2206—Special supports with preselected places to mount the resistance strain gauges; Mounting of supports
  • G01L1/2243—Special supports with preselected places to mount the resistance strain gauges; Mounting of supports the supports being parallelogram-shaped
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01G—WEIGHING
  • G01G21/00—Details of weighing apparatus
  • G01G21/24—Guides or linkages for ensuring parallel motion of the weigh-pans
  • G01G21/244—Guides or linkages for ensuring parallel motion of the weigh-pans combined with flexure-plate fulcrums
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01G—WEIGHING
  • G01G3/00—Weighing apparatus characterised by the use of elastically-deformable members, e.g. spring balances
  • G01G3/12—Weighing apparatus characterised by the use of elastically-deformable members, e.g. spring balances wherein the weighing element is in the form of a solid body stressed by pressure or tension during weighing
  • G01G3/14—Weighing apparatus characterised by the use of elastically-deformable members, e.g. spring balances wherein the weighing element is in the form of a solid body stressed by pressure or tension during weighing measuring variations of electrical resistance
  • G01G3/1402—Special supports with preselected places to mount the resistance strain gauges; Mounting of supports
  • G01G3/1412—Special supports with preselected places to mount the resistance strain gauges; Mounting of supports the supports being parallelogram shaped

Definitions

• the disadvantage of the known force measuring elements is that with a large nine-load the derived measuring signal changes greatly if the point of application of the load changes only slightly in the longitudinal direction of a beam - in the range of only 1/10 of a millimeter - as this is e.g wear and tear can occur.
• the beams 11, 12, 13 are each provided with an opening 25.
• This is essentially formed by the circular area 25' and the oval area 25'', which are connected to one another via an area 25''' with a rectangular cross-section.
• the areas 25' and 25'' have the same radii.
• bending points 40, 41, 42, 43 are created by markedly reduced material cross sections.
• the material cross sections of the bending points 40 to 43 are the same in each case, as illustrated by the arrows.
• Linkages 50, 51 of a parallel guide are formed between these bending points. In the event of deformation under load, pressure zones and tension zones form in each beam in the links 50, 51 at the bending points 40, 41, 42, 43.
• the point of application of the pin 19 can shift on the right-hand end 13' of the beam 13, as shown in dashed lines at 19' in FIG. Such a shift in the range of only 1/10 mm can easily result from wear. This follows when only two are arranged
• Strain gauges 20 and 21 on the top of the link 50 of the beam 13 a change in the measurement signal derived from them. These changes in the strain gauges 20 and 21 are asymmetrical, i.e. the signal changes are not equal in magnitude in the event of a deflection.
• a shoulder 26 is provided on the underside of the lower link 51, through which the outer cross section of the beam is enlarged, in such a way that the end 13 'on which the load acts by means of the pin 19 has the larger cross-section.
• FIG. 6 shows a modification with a slightly different design of the overload stop.
• the overload stop is formed by a stop plate 31, which is arranged on the inner beam 13 by means of the spacer sleeve 30 at a certain distance a' from the top of the inner beam 13 and laterally the outer bars 11, 12 overlaps.
• the two outer ends are seated on the outer beams 11, 12 and thus prevent deflection.
• FIG. 7 shows a second solution to the problem on which the invention is based.
• the step 26 on the underside of the lower link 51 is not formed. Instead, strain gauges 120 and 121 are also provided on the underside.
• the recess 25 is designed symmetrically, i.e. it consists of two circular recesses 25' of the same size and a rectangular recess 25 between them".
• the invention results in a load cell with optimal properties. They can be designed in such a way that they can be used even with small loads of e.g. 1 or 2 kg.
• the disadvantage of the known force measuring elements is that with a large nine-load the derived measuring signal changes greatly if the point of application of the load changes only slightly in the longitudinal direction of a beam - in the range of only 1/10 of a millimeter - as this is e.g wear and tear can occur.
• the object of the invention is to develop a force measuring element of the type mentioned in such a way that the sensitivity to changes in the point of application of the load is reduced or eliminated.
• a further development of the invention provides that the force measuring element is formed by three beams connected to one another in an E-shaped manner by means of a cross beam, and that the force measuring element is fastened to a console at the free ends of the outer beams and the load is absorbed at the free end of the middle beam .
• FIG. 7 shows another embodiment.
• the E-shaped one results Rotating beam arrangement according to FIG. 2, a double measuring path in that the two outer beams 11, 12 together have the same width as the middle beam 13 and therefore bend just as much under load as this. It also results in a low overall height and that the introduction of force and attachment are close together.

Landscapes

• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Measurement Of Force In General (AREA)
• Force Measurement Appropriate To Specific Purposes (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=6345968

Family Applications (2)

Family Applications After (1)

Country Status (6)

Families Citing this family (34)

Family Cites Families (15)

• 1988
  • 1988-01-26 DE DE3802153A patent/DE3802153A1/de active Granted
• 1989
  • 1989-01-19 EP EP89901465A patent/EP0397728A1/de active Pending
  • 1989-01-19 US US07/499,517 patent/US5183125A/en not_active Expired - Fee Related
  • 1989-01-19 JP JP1501260A patent/JP2521358B2/ja not_active Expired - Fee Related
  • 1989-01-19 ES ES198989100864T patent/ES2030914T3/es not_active Expired - Lifetime
  • 1989-01-19 WO PCT/EP1989/000057 patent/WO1989007245A1/de not_active Application Discontinuation
  • 1989-01-19 EP EP89100864A patent/EP0326017B1/de not_active Expired - Lifetime

Non-Patent Citations (1)

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