Device for measuring the filling level in a container using thermoelements
AssigneeKromberg & Schubert GmbH & Co. KG
InventorGottfried Domorazek
Life of this patent
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Abstract
In a device for measuring the filling level, thermoelements (20) are used which are disposed on a sheet-shaped support (25). The thermoelements (20) consist of two different materials and are disposed in two rows (71, 72) placed side by side. Two adjacent thermoelements (20) of said rows (71, 72) have a common junction point (23) that is heated. Both rows (71, 72) of thermoelements also have two additional junction points that are cold. A first group of thermoelements (20) is disposed with their supports (25) in the interior of the container and operate as measuring detectors. A second group of thermoelements (20) serves as reference sensors since they regulate the heat flow impinging upon the junctions points (23) relative to a defined reference voltage.
Claims13
Method for manufacturing a device (10), wherein the device serves for electronically measuring a filling level (16) of a liquid (15) in a container (11) or for gas quantity measurement, wherein the device is comprised of a set of thermoelements (20) which are arranged on a single sheet-shaped support (25) and connected in series and function as measuring sensors (43), wherein the method comprises the steps of:
- applying a first mask (67) onto a front side (26) of the sheet-shaped support (25), wherein the first mask (67) has in a double row (71, 72) two mirror-symmetrically arranged L-shaped cutouts (70, 70′ ) having long legs and short legs, respectively, and wherein the two L-shaped cutouts (70, 70′ ) in the double row (71, 72) are height-displaced with regard to the long legs (74, 74′) relative to one another and wherein leg ends (79, 79′ ) of the long legs face one another,
- applying either a nickel-chrome alloy (21) or a constantan via the first mask (67) onto the support (25) by sputtering and generating a double row (71, 72) of two L-shaped fields (73, 73′ ) on the front side (26) of the support (25),
- subsequently, placing a second mask (68) provided with a cutout onto the front side (26) of the support (25) and generating by sputtering of material a terminal tab (78) on the support (25),
- subsequently, placing a third mask (69) onto the front side (26) of the support (25), wherein the third mask (69) has two rows (71, 72) of two I-shaped cutouts (80, 80′),
- sputtering constantan (22) or a nickel-chrome alloy via the third mask (69) onto the front side (26) of the support (25) to generate two I-shaped fields (83, 83′ ), wherein the two I-shaped fields with respect to length as well as with respect to width and position are exactly aligned with the L-shaped fields (73, 73′) and overlap with end areas (81, 82 or 81′,82′) short L-legs (75, 75′) of a same row (71, 72) of the L-shaped fields and the legs ends (79, 79′) of long L-legs of the L-shaped fields (73, 73′) in a neighboring row (72, 71) and form a double row (71, 72) of two measuring sensor pairs (43),
- and, finally, placing first a fourth mask (85) and then a fifth mask (85, 86) onto the backside (27) of the support (25), wherein the fourth mask (85) has a narrow slot (88) and the fifth mask (86) has a wide slot (87),
- sputtering metallic material onto the backside via the fourth and fifth masks to form a common heating conductor (28) and a return line on the backside (27) of the support (25);
- wherein the heating conductor (27) is arranged in a longitudinal center of overlaps (82, 79′ or 82′, 79) of the double rows (71, 72) positioned on the front side and forms a common hot junction point (23) of the measuring sensor pairs (43),
- wherein overlaps (81, 75 or 81′, 75′) positioned in the two border areas of the double row (71, 72) form two cold junction points (24, 24′) of the two measuring sensor pairs (43),
- wherein the device has at least one reference sensor (33) for correction of a change of a heating current in the heating conductor (28) caused by a change of a surrounding temperature or an operating voltage.
Device for electronically measuring the filling level (16) of a liquid (15) in a container (11) or for gas quantity measurement, the device comprising:
- a set of thermoelements (20) arranged on a single sheet-shaped support (25) and connected in series and functioning as measuring sensors (43);
- wherein on a front side (26) of the sheet-shaped support (25) a double row (71, 72) of two L-shaped fields (73, 73′), having long L-legs with leg ends and short L-legs, is applied by sputtering a nickel-chrome alloy (21) or constantan via a first mask (67) onto the sheet-shaped support (25),
- a terminal tab (78) provided on the front side of the sheet-shaped support (25) by sputtering material via a second mask (68) onto the front side (26) of the support (25);
- two I-shaped fields generated by sputtering constantan (22) or a nickel-chrome alloy via a third mask (69) onto the front side (26) of the support (25), wherein the two I-shaped fields with respect to length as well as with respect to width and position are exactly aligned with the L-shaped fields (73, 73′) and overlap with end areas (81, 82 or 81′,82′) the short L-legs (75, 75′) of a same row (71, 72) of the L-shaped fields and the legs ends (79, 79′) of the long-L-legs of the L-shaped fields (73, 73′) in a neighboring row (72, 71) and form a double row (71, 72) of two measuring sensor pairs (43);
- a common heating conductor (28) and a return line provided on the backside (27) of the support (25) by sputtering metallic material onto the backside via a fourth mask and a fifth mask;
- wherein the heating conductor (27) is arranged in a longitudinal center of overlaps (82, 79′ or 82′, 79) of the double rows (71, 72) positioned on the front side and forms a common hot junction point (23) of the measuring sensor pairs (43);
- wherein overlaps (81, 75 or 81′, 75′) positioned in the two border areas of the double row (71, 72) form two cold junction points (24, 24′) of the two measuring sensor pairs (43);
- wherein the device has at least one reference sensor (33) for correction of a change of a heating current in the heating conductor (28) caused by a change of a surrounding temperature or an operating voltage;
- wherein the double row (71, 72) of the measuring sensors (43) has correlated therewith a set of reference sensors (33) arranged in a container interior (19);
- and
- wherein—as a function of a filling level (16)—a partial set (63) of the reference sensors (33) is positioned at a height area of liquid (15) while a remaining set (64) is positioned in a gas (17) above the liquid;
- wherein, however, the junction points (23, 24) of the partial set (63) of the reference sensors as well as of the remaining set (64) of the reference sensors (33)—independent of the filling level (16) in the container (11)—are always in thermal contact with a body (55, 56, 57) having always a constant thermal conductivity.
Dependencies are inferred from the claim text.