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EP-3971546-B1 - LOAD CELL

EP3971546B1EP 3971546 B1EP3971546 B1EP 3971546B1EP-3971546-B1

Inventors

  • HUANG YU-XIAN
  • LIANG, Yi-min
  • LU, CHIEH-HUANG

Dates

Publication Date
20260506
Application Date
20210512

Claims (8)

  1. A load cell (1b), comprising: an elastic element (10), wherein the elastic element (10) comprises: a first main body (11) comprising a first end portion (11a); a second main body (12) comprising a second end portion (12b); and a connection portion (13) connected between the first main body (11) and the second main body (12) and comprising a deformation region (13a), wherein the first end portion (11a), the connection portion (13) and the second end portion (12b) are stacked along an axial direction; at least one strain gauge (20) disposed in the deformation region (13a), wherein when a force (F1) is exerted on the first end portion (11a) in a first direction, the deformation region (13a) is deformed to drive the at least one strain gauge (20) to change shape, so that the force (F1) is measured and standardized, and wherein the deformation region (13a) and the at least one strain gauge (20) are extended along the axial direction; and a limitation element (30a) connected to the elastic element (10), wherein a gap (G) is formed between the limitation element (30a) and the elastic element (10), and the limitation element (30a) is configured to limit deformation of the deformation region (13a) corresponding to the gap (G) along the axial direction, so that the force (F1) is measured and standardized under a specific range.
  2. The load cell (1b) according to claim 1, wherein the first end portion (11a) and the second end portion (12b) are opposed to each other.
  3. The load cell (1b) according to claim 1, wherein the first main body (11) and the second main body (12) are concentric with each other.
  4. The load cell (1b) according to claim 1, wherein each of the first main body (11), the second main body (12) and the connection portion (13) is formed in a ring shape.
  5. The load cell (1b) according to claim 1, wherein the at least one strain gauge (20) comprises a plurality of strain gauges (S1, S2, S3, S4) arranged in the deformation region (13a) and served as a bridge circuit, which is configured to convert the force (F1) into an electrical signal.
  6. The load cell (1b) according to claim 1, wherein the gap (G) comprises a spaced distance (D), and the spaced distance (D) is inversely proportional to the force (F1), wherein when the spaced distance (D) is reduced to zero, the force (F2) is greater than the specific range, and the elastic element (10) is supported by the limitation element (30a) to limit deformation of the deformation region (13a).
  7. The load cell ( 1b) according to claim 1, wherein the first end portion (11a) is a stressed end located at a top surface of the first main body (11), and the second end portion (12b) is a mounted end located at a bottom surface of the second main body (12), wherein the first end portion (11a) and the second end portion (12b) are opposed to each other in the axial direction, and the gap (G) is located between the first end portion (11a) and the second end portion (12b).
  8. The load cell (1b) according to claim 1, wherein the force (F1) is measured and standardized under 200 tons (200000 kg).

Description

FIELD OF THE INVENTION The present disclosure relates to a load cell, and more particularly to a disc-type load cell capable of measuring a loading force under a specific range through the support of a limitation element and the limited displacement of a gap, and preventing the load cell from being damaged by irreversible permanent deformation due to overload. BACKGROUND OF THE INVENTION A load cell has a function of converting a force such as tension, compression, pressure or torque into an electrical signal that can be measured and standardized. As the force exerted on the load cell increases, the electrical signal changes proportionally. A strain gauge load cell is the kind most often found in industrial settings. It is ideal as it is highly accurate, versatile, and cost-effective. Structurally, a conventional strain gauge load cell includes an elastic element and a strain gauge. The strain gauge is secured on the elastic element. The elastic element is usually made of aluminum, alloy steel or stainless steel which makes it very sturdy but also minimally elastic. When a force is exerted on the load cell, the elastic element is slightly deformed, and the shape of the strain gauge secured on the elastic element is also changed, so as to change the resistance of the strain gauge. The resulting alteration to the resistance of the strain gauge is measured as voltage. Since the change in voltage is proportional to the amount of the force exerted on the load cell, the amount of the load force can be calculated from the output of the load cell. However, the conventional load cell performs a measurement in a specific range along a specific direction. For example, a conventional disc-type load cell is used to measure the axial force during the injection molding process. When the force exerted on the load cell exceeds a special range, the elastic element is overloaded, and the elastic element such as the disc structure is deformed and damaged irreversibly. US 3,365,689 A relates to a strain gage load cell wherein the load cell is in the form of a disc having radially formed holes therein and strain gages mounted on the shear strain zones of the holes in mutually crisscross axial relationship when the disc is in the horizontal plane to detect shear stresses when opposing forces are applied to the center of one side of the disc and to the periphery of the other side of the disc, said disc having a peripheral groove in intersecting relationship with the radially formed holes whereby a sealing means for the strain gages is provided. US 6,005,199 A describes a load cell comprises a column elastic body, a circle bore formed on a center portion of a first end surface of the column elastic body, a bottom wall of which constitutes a load acting surface, an annular concave groove formed on a second surface of the column elastic body being coaxial with the circle bore, a bottom portion of which constitutes a strain occurrence portion, a outer portion of which constitutes a fixing portion of thick cylinder configuration, and strain gages stuck on the strain occurrence portion. A distance "y" from the load acting surface to a surface of the strain occurrence portion is 0.2 to 2 times shortest distance "e" from a center axis of the column elastic body to the strain gages. WO 2020/158166 A1 discloses a force sensor equipped with a first structure, a second structure, a plurality of third structures, and a plurality of strain sensors. The first structure has three or more first elastic sections that are deformable in six axial directions. The second structure has three or more second elastic sections that can be deformed in six axial directions, and three or more relay sections that are connected to each of the second elastic sections and that are deformable in six axial directions. The plurality of third structures are provided between each of the relay sections of the second structure and each of the first elastic sections of the first structure. The plurality of strain sensors are provided between the first structure and each of the relay sections. US 8,726,741 B2 relates to a multiaxial force/torque sensor assembly and method for assembling such a sensor assembly are disclosed. The sensor assembly includes a set of at least two sensors each being made of strain gauges, which are each arranged at a definite angle and distance relative to each other and which are each fixed to a transducer body, which is mechanical contact with a printed circuit board. The printed circuit board includes clearances for each strain gauge as well as associated electronic components and wiring located on the remaining area of the printed circuit board which will monitor compressive and tensile stresses in the measurement directions of the sensors. The method includes positioning the strain gauges on the plane measurement surface of a transducer body in a definite arrangement; fixing the strain gauges to the transducer body by means of adhesives, and