Measuring and testing – With fluid pressure – Dimension – shape – or size
Reexamination Certificate
2002-10-15
2004-10-26
Cygan, Michael (Department: 2855)
Measuring and testing
With fluid pressure
Dimension, shape, or size
C073S037000
Reexamination Certificate
active
06807845
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a measurement apparatus and process for determining the position of an object relative to a reference surface, with at least one measurement nozzle, at least one reference nozzle, and at least one measurement device. The outlet opening(s) of the measurement nozzle(s) are located in the reference surface, and by way of a compressed air source air can be made available with a given feed pressure whereby the measurement device acquires one state variable or at least one of three state variables such as flow rate, pressure and speed of the air upstream of the measurement nozzle or measurement nozzles. In essence, the invention relates to pneumatic length measurement or pneumatic distance measurement or determination, the position of one object relative to a reference surface being regarded as the distance to be measured or determined.
2. Description of Related Art
Regarding the principles of pneumatic length measurement and the terminology used therein, the possible applications of pneumatic length measurement and the advantages associated with pneumatic length measurement, reference is made first of all to DIN 2271 “Pneumatic length measurement”, Part 1 “Principles, Processes,” September 1976, DIN 2271 “Pneumatic length measurement,” Part 2 “Construction features of devices for the high pressure range,” April 1976, DIN 2271-3 “Pneumatic length measurement,” Part 3 “Features of devices for the high pressure range, Requirements, Testing,” February 2000, and DIN 2271 “Pneumatic length measurement,” Part 4 “General data for application and examples,” November 1977, to literature references “PRODUCTION ENGINEERING I” published by Cert. Teacher. Alfred Reichard, professor in Pforzheim 7, revised edition, pages 46 to 50, and “New Innovations in Air Gauging and Control,” “TECHNOLOGY NEWS INTERNATIONAL,” November/December 1999, to the brochure “SYSTEM FOR PNEUMATIC-ELECTRICAL CONTROL AND MEASUREMENT” of Mawomatic Mayer Wonisch Mietzel GmbH, 59757 Arnsberg, and to the German patent disclosure document 42 32 630, German patent disclosure document 43 44 264, German patent disclosure document 197 34 374, German patent disclosure document 199 44 163, German Patent utility model 200 04 783, European Patent No. 0 380 967, European Patent No. 0 794 035 and U.S. Pat. No. 3,863,493.
In the pneumatic length measurement under consideration there are on the one hand series circuits, on the other networks, in the networks, those without bridges and those with bridges (compare DIN 2271, Part 1, Section 6 “Circuit”, 6.1 “Series circuit” and 6.2 “Network”, 6.2.1 “Network without bridge” and 6.2.2 “Network with bridge”).
It is noted that the expression “measured value transducer” is also used for the expression “measurement nozzle” and the expression “zero setter” is also used for the expression “reference nozzle” (compare DIN 2271, part 2, Section 3 “Display Devices”).
SUMMARY OF THE INVENTION
In accordance with the present invention, a measurement apparatus and process is provided, and by way of a compressed air source air with a specific feed pressure can be made available. Generally, the compressed air source is not a component of the measurement means under consideration, but is rather connected to an external compressed air source. This external compressed air source can be made such that it makes available air with the desired feed pressure relatively accurately and constantly over time. However, in the measurement apparatus in accordance with the invention, a filter is connected downstream of the compressed air connection, and also a pressure regulator (compare DIN 2271, Part 1, Section 3 “Measurement process” and Section 6 “Circuit”) which makes available compressed air with a certain feed pressure relatively constantly over time within the measurement mechanism.
In pneumatic length measurement, with reference to the feed pressure, it is distinguished between high pressure and low pressure (compare DIN 2271, Part 1, Section 5 “Pressure ranges”), high pressure being defined here as a feed pressure of ≧0.5 bar; low pressure being defined here as a feed pressure of ≦0.1 bar. Preferably, high pressure is used in the above explained sense.
In accordance with the invention, the measurement apparatus includes a measurement device that acquires one state variable or at least one of the three state variables such as flow rate, pressure and speed of the air upstream of at least one measurement nozzle. Essentially, in pneumatic length measurement, the dimension change, the change of the distance of the object to the reference surface, i.e., the gap change, is converted into a change in the flow rate and is detected (compare DIN 2271, Part 1, Section 3 “Measurement process”). Here we distinguish between (a) the process of measuring the flow rate in which the change in the flow rate is directly detected, (b) the pressure measurement process in which the change of flow rate is converted via a preliminary nozzle into a pressure change which is then detected, and (c) the speed measurement process in which the change of the flow rate is converted by a suitable throttle (Venturi nozzle) into a speed change which yields a pressure difference which is detected.
While therefore for the application of the flow rate measurement process only one measurement nozzle and one measurement device which detects the change of flow rate are required, for the application of the pressure measurement process and for the application of the speed measurement process, at least one additional part at a time is required, specifically, in the pressure measurement process at least one preliminary nozzle and in the speed measurement process, at least one suitable throttle (Venturi nozzle).
Several measurement nozzles can be used for the measurement means under consideration and in the process under consideration (parallel circuit (summation circuit) of measurement nozzles, compare DIN 2271, Part 1, Subsection 6.2.3, with FIG.
8
). Only one measurement nozzle is ever assumed below; likewise embodiments will always be encompassed which work with several measurement nozzles, in which therefore a parallel circuit (summation circuit) of measurement nozzles is implemented.
Within the framework of the invention, a measurement device can be used which detects one of the three state variables: flow rate, pressure and speed of the air in front of the measurement nozzle. However, several measurement devices can also be implemented which all detect either the same state variable, thus, the flow rate, the pressure, or the speed, or detect different state variables. Therefore, a first measurement device detects the state variable flow rate and the second measurement device the state variable pressure, or the first measurement device the state variable flow rate and the second measurement device the state variable speed, or the first measurement device the state variable pressure and the second measurement device the state variable speed, or the first measurement device the state variable flow rate, the second measurement device the state variable pressure and the third measurement device the state variable speed. It is always assumed below that there is only one measurement device which detects one of the three state variables flow rate, pressure and speed; likewise embodiments will always be encompassed which work with several measurement devices.
While the aforementioned DIN 2271 is referred as “Pneumatic length measurement,” the focus is on determination of the position of an object relative to a reference surface and it is stated that measurement device “detects” one state variable or the measurement devices “detect” at least one of the three state variables: flow rate, pressure and speed of the air in front of the measurement nozzle or the measurement nozzles. This difference in terminology has the following justification.
“Measurement” could be defined as proportional detection of the distance of an object relative to the reference surface. But the invention is n
Halbinger Lorenz
Kathan Benno
Wagner Alfred
Cygan Michael
i f m electronic GmbH
Nixon & Peabody LLP
Safran David S.
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