Load cell and weighing apparatus including a strain sensor welded to a strain inducing device
First Claim
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1. A load cell for use in detecting a load imposed thereon, said load cell comprising:
- a strain inducing means made of metal for generating a strain as a function of the load;
a strain sensor including a metal substrate having a strain detecting element formed thereon for detecting the strain generated in the strain inducing means, said metal substrate being of a generally rectangular shape having a pair of first sides opposite and parallel to each other and a pair of second sides opposite to each other, said metal substrate having a pair of strain generating areas defined therein and situated between said first sides while separated a distance from each other in a direction parallel to any one of the first sides, each of said strain generating areas being where stress build-up occurs;
said detecting element being positioned at each of said strain generating areas for detecting the strain generated at the respective strain generating area and away from each of the second sides of the metal substrate;
said strain sensor being mounted in the strain inducing means with the second sides of the metal substrate, spot-welded to said strain sensor, being oriented along a horizontal plane when in an unloaded mode and said second sides being positioned on horizontal mount surfaces of mount portions of the strain inducing means; and
said metal substrate being a thin plate having a smaller cross-sectional area perpendicular to said first sides, than said mount portions.
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Abstract
A load cell for detecting a load imposed thereon and for improving the productivity thereof. The load cell includes a strain inducing device (1) made of metal and including a strain generating area (6) for generating a strain as a function of the load, and a strain sensor (40) including a metal substrate (41) having a strain detecting element (43) formed thereon for detecting the strain generated at the strain generating area (6) of the strain inducing means (1). The strain sensor (40) is mounted on the strain inducing device (1) with the metal substrate (41) welded thereto.
34 Citations
31 Claims
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1. A load cell for use in detecting a load imposed thereon, said load cell comprising:
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a strain inducing means made of metal for generating a strain as a function of the load; a strain sensor including a metal substrate having a strain detecting element formed thereon for detecting the strain generated in the strain inducing means, said metal substrate being of a generally rectangular shape having a pair of first sides opposite and parallel to each other and a pair of second sides opposite to each other, said metal substrate having a pair of strain generating areas defined therein and situated between said first sides while separated a distance from each other in a direction parallel to any one of the first sides, each of said strain generating areas being where stress build-up occurs; said detecting element being positioned at each of said strain generating areas for detecting the strain generated at the respective strain generating area and away from each of the second sides of the metal substrate; said strain sensor being mounted in the strain inducing means with the second sides of the metal substrate, spot-welded to said strain sensor, being oriented along a horizontal plane when in an unloaded mode and said second sides being positioned on horizontal mount surfaces of mount portions of the strain inducing means; and said metal substrate being a thin plate having a smaller cross-sectional area perpendicular to said first sides, than said mount portions. - View Dependent Claims (2, 3, 4, 5, 8, 9, 10, 11, 12, 15, 16, 17, 18, 19, 21, 22, 23)
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6. A load cell for use in detecting a load imposed thereon, said load cell comprising:
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a strain inducing means made of metal and operable to generate a strain as a function of the load, said strain inducing means comprising generally elongated first and second structures with the first structure positioned above the second structure so as to define a generally hollow therebetween, an intermediate plate means sandwiched between the first and second structures; a strain sensor including a metal substrate having a strain detecting element formed thereon for detecting the strain generated in the strain inducing means, said strain sensor being positioned within the hollow and mounted in the strain inducing means with said metal substrate welded thereto; wherein said first structure is of one-piece construction including a pair of upper rigid body forming regions opposite to each other and connected together by means of an upper beam, said upper rigid body forming regions constituting respective upper portions of the fixed rigid body adapted to be secured to a base and a movable rigid body adapted to receive the load and wherein the second structure is of one-piece construction including a pair of lower rigid body forming regions and opposite to each other and connected together by means of a lower beam, said lower rigid body forming regions constituting respective lower portions of the fixed and movable rigid bodies; and
,wherein said intermediate plate means includes a first intermediate plate member sandwiched between first rigid body forming regions of the first and second the upper and lower portions of the fixed rigid body, and a second intermediate plate member sandwiched between the upper and lower portions of the movable rigid body, said first and second intermediate plate members having respective ends confronting with each other, said metal substrate of said strain sensor being welded at its opposite ends to said ends of the first and second intermediate plate members. - View Dependent Claims (24, 26)
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7. A load cell for use in detecting a load imposed therein, said load cell comprising:
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a strain inducing means made of metal and operable to generate a strain as a function of the load, said strain inducing means comprising generally elongated first and second structures with the first structure positioned above the second structure so as to define a generally hollow therebetween, an intermediate plate means sandwiched between the first and second structures; a strain sensor including a metal substrate having a strain detecting element formed thereon for detecting the strain generated in the strain inducing means, said strain sensor being positioned within the hollow and mounted in the strain inducing means with said metal substrate welded thereto; wherein said first structure is of one-piece construction including a pair of upper rigid body forming regions opposite to each other and connected together by means of an upper beam, said upper rigid body forming regions constituting respective upper portions of the fixed rigid body adapted to be secured to a base and a movable rigid body adapted to receive the load and wherein the second structure is of one-piece construction including a pair of lower rigid body forming regions and opposite to each other and connected together by means of a lower beam, said rigid body forming regions constituting respective lower portions of the fixed and movable rigid bodies; and
,wherein said intermediate plate means comprises a single plate member having an opening defined at an intermediate portion thereof, opposite peripheral lip regions of said opening defining respective mounts to which the opposite ends of the strain sensor are welded while traversing across the opening. - View Dependent Claims (25, 27)
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13. A method of manufacturing a load cell including a strain inducing means made of metal and operable to generate a strain as a function of a load imposed on the strain inducing means, and a strain sensor having a strain detecting element formed on a metal substrate and mounted on said strain inducing means, said metal substrate being of a generally rectangular configuration having a pair of first sides opposite and parallel to each other and a pair of second sides opposite to each other and lying perpendicular to any one of said first sides, said method comprising the steps of:
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forming first and second strain generating areas in said metal substrate at a location between said first sides while separated a distance from each other in a direction parallel to any one of the first sides, each of said strain generating areas being where stress build-up occurs; mounting the strain detecting element on each of the strain generating areas of the metal substrate so that the strain generated at the respective strain generating area may be detected by the strain detecting element, thereby completing a strain sensor; and mounting the strain sensor in the strain inducing means with the second sides of the metal substrate spot-welded to horizontal mount surfaces of mount portions of said strain inducing means such that said strain sensor is in a horizontal plane when in an unloaded state, wherein said metal substrate is formed as a thin plate having a smaller cross-sectional area perpendicular to said first sides than said mount portion. - View Dependent Claims (14, 20)
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28. A load cell for use in detecting a load imposed thereon, said load cell comprising:
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a strain inducing means made of metal and operable to generate a strain as a function of the load; a strain sensor including a metal substrate having a strain detecting element formed thereon for detecting the strain generated in the strain inducing means, said metal substrate being of a generally rectangular shape having a pair of first sides opposite and parallel to each other and a pair of second sides opposite to each other, said metal substrate having a pair of strain generating areas defined therein and situated between said first sides while separated a distance from each other in a direction parallel to any one of the first sides, each of said strain generating areas being where stress build-up occurs; said detecting element being positioned at each of said strain generating areas for detecting the strain generated at the respective strain generating area and away from each of said second sides of the metal substrate; said strain sensor being mounted in the strain inducing means with the second sides of the metal substrate welded thereto without allowing the strain generating areas to contact a surface of the strain inducing means;
said strain sensor being oriented along a horizontal plane when in an unloaded mode and said second sides being positioned on horizontal mount surfaces of mount portions of the strain inducing means; andsaid metal substrate being a thin plate having a smaller cross-sectional area perpendicular to said first sides, than said mount portions. - View Dependent Claims (29, 30, 31)
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Specification