METHOD AND DEVICE FOR MEASURING THE WEIGHT OF A LOAD TO BE HOISTED ONTO A LOADING AREA

• US 20140069728A1
• Filed: 02/06/2012
• Published: 03/13/2014
• Est. Priority Date: 02/11/2011
• Status: Active Grant

• Current Assignee: DIGI SENS Holding AG
• Original Assignee: Digi Sens AG
• Inventors: Lustenberger, Martin
• Granted Patent: US 9,534,948 B2
• Time in Patent Office: Days
• US Class Current: 177/1
• CPC Class Codes: B60P 1/6463 fitted with articulated beams for longitudinal displacement of the container
• CPC Class Codes: G01G 19/12 having electrical weight-sensitive devices
• CPC Class Codes: G01M 1/122 Determining position of centre of gravity

Abstract

The invention provides a method and a device for measuring the weight of a load, which is displaced with a load lifting device over the edge of a raised loading surface and thus pulled onto the same or pushed down from the same, wherein during this operating process, in a support of the load lifting device loaded by the load, the force currently acting due to the displacement of the load is measured during the passage through a predetermined weighing window and the weight of the load is determined mathematically from the course thereof. Preferably, the load sensor is constructed as a tube which is equipped with two deformation sensors equipped essentially at right angles to one another.

Claims

1. A method for measuring the weight of a load which is displaced with a load lifting device (2) over the edge (11) of a raised loading surface (4) and thus pulled onto the same or pushed down from the same, characterised in that during this operating process and as long as the load rests in a raised manner on the edge (11) of the loading surface (4) during the displacement from the ground, in a support of the load lifting device (2) loaded by the load and moving the same, during the passage of the same through a predetermined movement position, a force (A, Q) currently acting in it due to the displacement of the load is measured and the same is intended for mathematically determining the weight of the load.

2. The method according to claim 1, wherein the axial force (A) currently acting in the support of the load lifting device (2) is measured and the predetermined movement position of the support (5) of the load lifting device (2) corresponds to the position thereof directly before the placement point of the load on the loading surface (4).

3. The method according to claim 2, wherein for mathematically determining the weight of the load, the force thereof acting on the edge (11) of the loading surface (4) is further used.

4. The method according to claim 3, wherein the edge (11) of the loading surface (4) is formed by means of rollers (12), which are arranged on at least one roller support (39) provided on the loading surface (4), and wherein the weight forces (R) of the load accommodated by the rollers (12) during the passage through the predetermined movement position of the support of the load lifting device (2) are determined from the flexural torque acting in the at least one roller support (39) due to the load and additionally used for mathematically determining the weight of the load, and wherein the moment acting in the at least one roller support (39) is preferably detected by means of the flexion of the roller support (39).

5. The method according to claim 3, wherein the edge (11) of the loading surface (4) is formed by means of rollers (12), which are arranged on at least one roller support (39) provided on the loading surface (4), and wherein the weight forces (R) of the load accommodated by the rollers (12) during the passage through the predetermined movement position of the support of the load lifting device (2) are determined from the lateral force acting in the at least one roller support (39) due to the load, and wherein the lateral force is preferably determined by means of a load measuring sensor which has two deformation sensors inserted into a tube at right angles to one another.

6. The method according to claim 1, wherein the lateral force (Q) acting in the support of the load lifting device (2) is measured, the predetermined movement position extends over a weighing window and the weight of the load is determined from the course of the lateral force (Q) in the weighing window, wherein the weighing window is preferably delimited on the one side by the moment at which the rear end of the load is lifted from the ground or placed on the same.

7. The method for measuring the weight of a load according to claim 5, wherein the moment at which the rear end (13) of the load is lifted from the ground or placed on the same is determined mathematically from the geometry of the load lifting device (2) and the geometry of the load or is detected by means of a sensor or is detected due to the reduced shaking of the load, wherein the degree of shaking is preferably determined from a lateral force portion which changes back and forth rapidly.

8. The method for measuring the weight of a load according to claim 6, wherein the weighing window is delimited on the other side by the moment at which the front end of the load (10) is placed on the loading surface (4) or is lifted from the same by means of the load lifting device (2).

9. The method according to claim 8, wherein the weighing window has a zone adjoining the other side, in which the load is displaced along a path along the loading surface (4) with an only slightly raised front end (10), and wherein the lateral force Q determined in the process is used for mathematically determining a correction variable corresponding to the frictional force R of the load, which is used in turn for mathematically determining the weight of the load adjusted for friction.

10. The method for measuring the weight of a load according to claim 6, wherein the following steps are provided in the mathematical determination of the load:

a) determining the lateral force Q as a function of the progressive transport movement of the load lifting device (2) in the measuring window, calculating therefrom the tensile force Z of the load lifting device (2) and calculating an area value corresponding to the product of the tensile force Z and path s of the progressive transport movement

b) multiplying this area value by a geometry factor for the load lifting device (2) actually used and load which corresponds to a proportionality factor between the area value for a load weight and this load weight.

11. The method for measuring the weight of a load according to claim 10, wherein the proportionality factor is mathematically determined before an actual work operation from the geometry of the load lifting device (2) and load and is calibrated by means of the correct displacement of one or a plurality of standard loads.

12. A load measuring device for executing the measuring method according to claim 1, with at least one support (5) which can be moved in such a manner for the displacement of a load that the load is displaced over the edge (11) of a raised loading surface (4) and thus pulled onto the same or pushed down from the same, characterised by a load measuring cell (16), arranged in a support section (15) of the support (5), for determining a force acting in the support section (15) during the work movement and by a computer operatively connected to the load measuring cell (16), which is constructed to analyse the force signals of the load measuring cell (16) in a predetermined movement position of the support section (15) and to determine the weight of the load using the same.

13. The load measuring device according to claim 12, wherein the load measuring cell (16) is constructed to measure the axial force (A) prevailing in the support section (15) and the computer is constructed to analyse the axial force (A) prevailing directly before the placing of the load onto the loading surface (4) and to determine the weight of the load on the basis of the same.

14. The load measuring device according to claim 11, wherein the load measuring cell (16) is constructed as a tube (20) and arranged perpendicularly to the longitudinal axis of the support section (15), and wherein two deformation sensors (22, 23) are inserted in the tube (20) and arranged at an angle of essentially 90°

with respect to one another in such a manner that in the case of changed axial force A, the one sensor (22, 23) measures the enlargement of the one assigned diameter of the tube (20) and the other sensor (23, 22) measures the reduction in size of the other diameter assigned to the same, wherein the deformation sensors (22, 23) are preferably constructed as vibrating wire sensors.

15. The load measuring device according to claim 12, wherein rollers (12) for the displacement of the load over the edge (11) are provided at the edge (11) of the loading surface (4), which rollers (12) are arranged on at least one roller support (39) which, in the event of a loading of the rollers (12) by a load, flexes in accordance therewith, and further sensors (48) are provided, which detect the flexion of the at least one roller support (39), and wherein the computer is constructed to analyse the flexion signals of the sensors and likewise to use the same for determining the weight of the load.

16. The load measuring device according to claim 12, wherein the load measuring cell (16) is constructed to measure the lateral force Q prevailing in the support (15) and the computer is constructed to calculate the weight of the load from the course of the lateral force (Q) in a predetermined measuring window.

17. The load measuring device according to claim 12, wherein the load measuring cell (16) is constructed as a tube (60) and arranged perpendicularly both to the longitudinal axis (54) of the support section (15) and to the lateral force Q generated in the same by means of the movement of the load, and wherein two deformation sensors (65, 66) are inserted in the tube (60) and arranged at an angle of essentially 90°

with respect to one another in such a manner that in the case of changed lateral force Q, the one sensor (65, 66) measures the enlargement of the one assigned diameter (63, 62) of the tube (60) and the other sensor (66, 65) measures the reduction in size of the other diameter (62, 63) assigned to the same, wherein the deformation sensors (65, 66) are preferably constructed as vibrating wire sensors.

18. The load measuring device according to claim 16, wherein the computer is constructed to execute the following computing steps:

a) determining the lateral force Q from the signal values of the load measuring cell (16) as a function of the progressive transport movement of the load lifting device (2) in the measuring window, calculating therefrom the tensile force Z of the load lifting device (2) and calculating an area value corresponding to the product of the tensile force Z and path s of the progressive transport movement

b) multiplying this area value by a geometry factor for the load lifting device actually used and load which corresponds to a proportionality factor between the area value for a load weight and this load weight, and wherein the computer is further constructed to store this product in a memory assigned to it and/or to display the same as weight of the load.

19. The load measuring device according to claim 18, wherein the computer is further constructed

c) to determine a correction variable corresponding to the frictional force R from the signal values of the load measuring cell (16) during the advance of the load along the loading surface (4) between s₂ and s₃ and

d) to process this correction variable using the product of area value and proportionality factor to give a more accurate value for the weight.

20. The load measuring device according to claim 12, wherein the computer is constructed to store determined data about work operations performed on a preferably external storage medium and/or to read data relating to the load, such as the geometry thereof or a proportionality factor assigned to a load from a preferably external storage medium and to use the same for determining the weight of the load.