Pneumatic Leak Measurement System Based on Absolute Pressure Drop Measurement, with Reference Sample Differential Compensation

Abstract

The present invention specifically relates to the pneumatic and electronic application of a pneumatic leak meter based on absolute pressure drop measurement having the peculiarity of compensating for ambient variations such as ambient temperature and temperature of the measured part, as well as mechanical deformations of the component being tested caused by the pressure being applied.

Claims

1. A system (100) for measuring pneumatic leaks of an object (4), said system being of the differential pressure drop type, characterized in that the system (100) comprises two absolute pressure drop measurement circuits (7, 8), wherein the respective pressure values measured by the two absolute pressure drop measurement circuits (7, 8) are subtracted from one another by related electronics of the system (100).

2. The system (100) according to claim 1, wherein each absolute pressure drop measurement circuit (7, 8) comprises a relative pressure meter (2, 3) operating relative to ambient pressure.

3. The system (100) according to claim 1, wherein an end portion of one (8) of the absolute pressure drop measurement circuits (7, 8) is connected to a reference element or sample (5), and wherein the electronics of the system (100) are configured to: a. acquire, or sample, and save, in a permanent data array, a measurement trend of the reference part (5), and b. determine, during the measurements, a difference in real time between the acquired wave and the saved array, point by point in phase with time.

4. The system (100) according to claim 1, wherein an end portion of one (8) of the absolute pressure drop measurement circuits (7, 8) is not connected to any reference element or sample (5) and is plugged or kept closed, and wherein the electronics of the system (100) are configured to acquire both pressure values and to continuously sample a difference between both pressure values.

5. A differential pressure drop measurement method for measuring pneumatic leaks of an object (4), in particular using a system according to any one of the preceding claims, wherein the method includes performing subtraction of pressure values measured by two absolute pressure drop leak measurement circuits (7, 8) one from the other.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0033] This and other features of the present invention will appear more clearly from reading the following detailed description of embodiments of the invention which are presented solely by way of non-restrictive examples and illustrated by the attached drawings in which:

[0034] FIG. 1 illustrates a schematic pneumatic diagram of a pneumatic leak measurement system according to an embodiment of the invention; and

[0035] FIG. 2 illustrates basic electronics of the system shown in FIG. 1, configured to acquire two pressure values (P_TEST/Press_Test and P_REF/Press_Ref) and to continuously sample a difference (Press_Diff) between said values.

DESCRIPTION OF THE INVENTION

[0036] With particular reference to FIG. 1, reference numeral 100 generally designates the system for measuring pneumatic leaks of an object or part 4 in accordance with an embodiment of the present invention, namely a pneumatic leak meter based on absolute pressure drop measurement that compensates for ambient variations such as ambient temperature and temperature of the part 4 being measured, as well as mechanical deformations of the component being tested caused by pressure being applied, as detailed below.

[0037] More specifically, reference numeral 1 designates a pneumatic “filling” or pressurization section of the object 4 being measured.

[0038] Industrial air, designated by reference numeral 6 in FIG. 1, is commonly used to carry out the filling or pressurization phase.

[0039] As shown in the diagram of FIG. 1, filling or pressurization of the object 4 to be measured is performed via a common pneumatic valve and a first circuit 7. This first circuit 7 includes a dedicated pneumatic valve for selectively coupling the first circuit 7 to the aforementioned pressurization section 1 during the pressurization phase and for selectively decoupling the first circuit 7 from the pressurization section 1 during the measurement phase, as well as a pressure meter 2 connected on the pneumatic line with the part or object 4 to be tested. In that respect, an end portion of the first circuit 7, namely of the pneumatic line thereof, is connectable to the part or object 4 to be tested, as shown.

[0040] Filling or pressurization of the test object 4 is monitored over time by the pressure meter 2. In the illustrated embodiment, the pressure meter 2 is a relative pressure meter operating relative to ambient pressure, i.e. the pressure value measured by the pressure meter 2 is measured relative to ambient pressure.

[0041] The aforementioned first circuit 7 thus acts as a first absolute pressure drop measurement circuit 7 for the purpose of measuring pressure decay over time of the test object 4.

[0042] The system 100 also includes a second absolute pressure drop measurement circuit 8, similar to the first circuit 7, likewise including a dedicated pneumatic valve and a pressure meter 3 connected on the relevant pneumatic line of the circuit 8. Similarly to pressure meter 2, the pressure meter 3 is a relative pressure meter operating relative to ambient pressure.

[0043] An end portion of the measurement circuit 8, namely of the pneumatic line thereof, can be connected or not to a reference element or sample 5 as a function of the required measurement, that is: [0044] in case of symmetrical differential measurement, the reference element/sample 5 is connected to the end portion of the measurement circuit 8; [0045] in case of asymmetrical differential measurement, the reference element/sample 5 is not connected to the end portion of the measurement circuit 8, which end portion is plugged or kept closed in such case.

[0046] In the asymmetrical differential measurement mode (with no reference element/sample connected to the measurement circuit 8), the electronics associated with the system 100 of FIG. 1 (see FIG. 2 which shows the basic functionality thereof) are configured to acquire both pressure values measured by the pressure meters 2, 3 (which pressure values are designated in FIG. 2 as test value P_TEST/Press_Test and reference value P_REF/Press_Ref) and therefore to continuously sample the difference between the two pressure values.

[0047] Alternatively, in the case of symmetrical measurement (with a hermetic sample/reference part 5 connected to the measurement circuit 8), the electronics associated with the system 100 of FIG. 1 (see again FIG. 2) are configured to: [0048] acquire, or sample, and save in a permanent data array, a measurement trend of the reference part 5, and [0049] determine, during the measurements, a difference in real time between the acquired wave and the saved array, point by point in phase with time.

[0050] The aforementioned method ensures that the resulting differential measurement is free from and unaffected by mechanical stress phenomena and variations in ambient temperature.

[0051] More specifically, in addition to the associated electronics, the system 100 may further provide for the management of calculations using software such that it is possible to: [0052] measure the trend of the sample reference part 5 at intervals of time, thereby avoiding unnecessary mechanical stresses and heat accumulation; [0053] allow variations in ambient temperature to be “chased” or tracked.

[0054] To do so (and also to avoid creating unnecessary downtime in production cycles), via hardware indications of external automations, and internal logic of the instrument, the software may further manage a “reservation” and “execution” cycle of the “reference” sample part, and via percentage parameters of the totality of the measurements taken, as well as minimum and maximum times, take measurement samples at intervals of time that are long enough not to wear out the mechanical characteristics of the reference part, but frequent enough to “chase” or track ambient variations.

[0055] Sampling takes place in any case each time the system is turned on, and special “average” algorithms on the acquired points enable the different reference curves acquired to be refined over time and filtered, while avoiding any sudden and unwanted spurious effects.

[0056] Naturally, a person skilled in the art can undertake further modifications and variations to the invention described above in order to meet specific contingent applicational requirements, said variations and modifications nonetheless falling within the scope of protection defined in the subsequent claims.

ADVANTAGES

[0057] Compared to a traditional differential pressure drop meter based on a differential transducer, the present invention brings the following technical improvements: [0058] Resolves the problem of “apparent repeatability” in the case of “symmetrical differential measurement”. [0059] Resolves the problem of measurement uncertainty in the case of “central-zero differential” measurement, namely with two parts being tested simultaneously. [0060] Resolves the drift in the pneumatic branch of reference in the case of “asymmetrical differential measurement”, by means of partial and controlled discharging of the reference branch for test purposes. [0061] Resolves the technical problem of intrinsic lack of safety of traditional differential pneumatic systems. [0062] Achieves greater construction simplicity. [0063] Ensures greater reliability over time. [0064] Offers the possibility of “stepwise” diagnosis of the two measurement branches.