Variable range load cell system and method of application
First Claim
1. A load cell arrangement which is operative for precisely measuring loads over a range beyond the functional range of a single load cell and which comprises:
- a hollow case having a top and bottom panel;
a load measuring element positioned within said case with a first end connected to the bottom panel of said case;
load transfer means connected to a second end of the load measuring element for coupling the load measuring element to a fixed reference;
load monitoring means for monitoring the amount of a load applied between the bottom panel of said case and said fixed reference and supplying an output signal indicating the amount of said load;
a source of fluid under pressure; and
a variable force means interposed between the top pane of said case and said second end of the load measuring element for applying fluid under pressure from said source across said load measuring element, responsive to said output signal for counter acting the load exerted upon the load measuring element permitting said load measuring element to measure loads greater than said functional maximum load measuring range when said output signal indicates that the amount of said load applied between the bottom panel of said case and said fixed reference is approaching the maximum functional load range of said load cell measurement element.
3 Assignments
0 Petitions
Accused Products
Abstract
A variable load cell arrangement operative for precisely measuring loads over a range beyond the range of a single conventional single low range load cell. The arrangement includes a low range measuring element positioned in a case and having one end adapted to be connected through the case to a load and the opposing end coupled to a fixed reference. A variable pressure means, such as a controllable bellows, is interposed in the case between the load element and an end of the case whereby a predetermined force may be selectively applied to the load measuring element in a direction opposing the load to relieve the strain on the element and permit it to continue to function in an extended range. Electrical circuits, including Wheatstone bridges, are coupled to the load measuring element and provide an electrical output indicative of the applied load and an electrical output that is used to control the variable pressure means.
16 Citations
16 Claims
-
1. A load cell arrangement which is operative for precisely measuring loads over a range beyond the functional range of a single load cell and which comprises:
-
a hollow case having a top and bottom panel; a load measuring element positioned within said case with a first end connected to the bottom panel of said case; load transfer means connected to a second end of the load measuring element for coupling the load measuring element to a fixed reference; load monitoring means for monitoring the amount of a load applied between the bottom panel of said case and said fixed reference and supplying an output signal indicating the amount of said load; a source of fluid under pressure; and a variable force means interposed between the top pane of said case and said second end of the load measuring element for applying fluid under pressure from said source across said load measuring element, responsive to said output signal for counter acting the load exerted upon the load measuring element permitting said load measuring element to measure loads greater than said functional maximum load measuring range when said output signal indicates that the amount of said load applied between the bottom panel of said case and said fixed reference is approaching the maximum functional load range of said load cell measurement element. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
-
-
9. A variable load cell measuring arrangement for accurately measuring loads over a predetermined functional range comprising:
-
a load measuring element operative through a predetermined range that is connected to a load and at the other end to a fixed reference; a case having a top and a bottom panel surrounding the load measuring element with the load measuring element connected to the bottom panel of said case; variable pressure means interposed between the load measuring element and the top panel of said case; a source of fluid under pressure; and means to selectively supply said fluid under pressure to the variable pressure means when the load exceeds a predetermined limit so that the variable pressure means exerts a pressure directly opposing the test load thereby permitting the load measuring element to continue to function within the operative range. - View Dependent Claims (10, 11, 12)
-
-
13. A method for accurately measuring loads applied to a load measuring element positioned in a case, said loads being greater than the functional range of a measuring element which comprises the steps of:
-
applying a predetermined load to said measuring element having a defined maximum functional load capability; determining the load applied to the load measuring element; and applying;
when the load applied to the load measuring element exceeds said maximum load capability of said measuring element, a predetermined counter acting force to the casing surrounding said load measuring element in opposition to the load for permitting the load measuring element to continue to function above its maximum functional load capability. - View Dependent Claims (14, 15, 16)
-
Specification