1. Technical Field
The present invention relates to a device for measuring in a continuous way the modification of the physical contact between two curvilinear contact surfaces on the basis of a measurement of resistance.
By curvilinear, one means a surface that is built on a direct curve and sections of this direct curve. A section is a line segment, rectilinear or not, which is definite for each point of the direct curve. The sections form a set of rectilinear lines or not that cross the direct curve but do not cross each other. The direct curve and the set of sections define a surface. The surface thus defined can be plane or not. We call edges of the contact surface the set of the endpoints of the sections. The curvilinear surface thus has two edges. It also has two ends, confused or not, which are the two sections located at the ends of the direct curve and are called ends of the surface. We call joint a curvilinear contact surface between two elements.
2. Description of Related Art
Detection of either leak or matter intrusion is traditionally achieved with the help of external sensors detecting the abnormal presence of the matter following its passage between two contact elements that should carry out a tight border between two zones. These sensors can be sensors measuring the pressure of a fluid, or sensors allowing the detection of a chemical compound, or sensors allowing the detection of matter presence or any other type of sensors according to the application. The sealing degradation is then detected when the matter passage between the two zones took place, i.e. after the break of sealing, which can be saw as a break of the contact surface integrity forming a way between both edges of the surface. The extent of the degradation is then estimated from the quantity of matter that crossed from one zone to the other by its path.
The monitoring of sealing of tight doors and tight trap doors is also usually carried out by measurement of difference in pressure, which do not make is possible to check the correct positioning of the seal of the door or the trap door for example in U.S. Pat. Nos. 4,202,201 issued May 13, 1980, or 5,404,747 issued Apr. 11, 1995.
Another technique for detecting leaks consists in measuring the pressure on the sealing membrane. The leak is thus detected by a pressure drop on the membrane surface following the transition from a hydrostatic mode of pressure to a dynamic mode of pressure. This technique does not make it possible either to detect the surface deterioration before the leak occurs. A possible pressure measuring device system for this application is disclosed in the U.S. Pat. No. 4,446,424 issued May 1, 1984.
Another technique for detecting leaks, disclosed in the G. B. Pat. 1,535,047 issued Dec. 6, 1978, is based on the detection of the emergence of a flow of electricity following the passage of a conductive liquid between the two contact surfaces. This method, of all-or-nothing-type, does not make it possible to measure the extent of the seal degradation. Moreover, it can only be used to detect the intrusion of conductive matter between the two contact surfaces. This method does not allow to detect a seal deterioration by the intrusion of insulating matter.