Measuring and testing – Vibration – Sensing apparatus
Reexamination Certificate
2000-12-05
2002-08-06
Williams, Hezron (Department: 2856)
Measuring and testing
Vibration
Sensing apparatus
C702S056000
Reexamination Certificate
active
06427537
ABSTRACT:
FIELD OF INVENTION
The present invention relates generally to measuring equipment and more particularly to measuring equipment of the kind that includes a plurality of sensors which are each adapted to sense a measurement magnitude, and which further include a “measuring card” to which said sensors are connected, and a computer unit to which said measuring card is connected.
The invention may be based on providing said measuring card with two mutually opposite electrical contact means, of which a first is adapted for coaction with a corresponding electrical contact means belonging to a computer unit, and the other is adapted for coaction with a corresponding sensor-mounted electrical contact means and thereby create conditions to form a simple and light measuring equipment that can be brought along by a mechanic or repairman in order to evaluate an imbalance or balance of a rotating machine or shaft on site.
The invention also includes the embodiment where a rotating machine can be continuously controlled with regards to balance or imbalance by including the measuring card in a controlling unit and/or process-regulating unit and to thereby integrate the measuring equipment with the unit.
The inventive measuring equipment is based on adapting a first sensor to sense a prevailing frequency generated by an object to be measured, while a second sensor is adapted to sense prevailing tacho-pulses generated by the object being measured.
More particularly, the measured object includes a rotating object, such as a shaft or axle, and the measuring equipment functions to enable an evaluation of different types of imbalance in the rotary movement of the rotating object from measurements received from the rotation of the object, such as a result of cracks in the object, rotational asymmetric imbalances, varying degrees of imperviousness in the material from which the object is made, and so on.
BACKGROUND OF THE INVENTION
Various designs and configurations of measuring equipment of the aforedescribed kind are known to the art.
For instance, there is known to the art measuring equipment that includes one or more sensors for sensing one or more temperatures with the aid of a measuring card and a computer unit to this end.
One such measuring card is marketed in Sweden under the designation Ines DMM & DAQ I218 by PC Card Distribution Skandinavien AB, Solna, Sweden.
Measuring equipment of this kind thus enables one or more prevailing or current temperatures to be presented on the screen of the computer unit.
It is also known to configure a measuring card of this kind as a digital multimeter having a determined digital resolution or a 16-channel data collecting system.
In this regard, there is also provided a data collection of analogue levels with 24-bit resolution.
The measuring cards are comprised of an A/D converter and a digital electronic unit, among other things.
It is also known to enter into the computer unit information relating to the front surface of a known measuring unit and to present relevant, or current, values such as temperature values, within the area of the presentation surface of said measuring unit.
Patent Publication GB-A-2 177 509 teaches a method and an arrangement for detecting axial cracks in a rotor of rotary machines, by sensing vibration frequencies with the aid of sensors (
38
,
40
) and correlating the frequency of the vibrations with the angular position of the rotor with the aid of a sensor (
37
).
Data relating to angular velocity is obtained through the medium of a cogwheel (
35
) and a magnetic sensor (
37
), said cogwheel (
35
) having ten equidistant teeth and therewith producing a detectable tacho-pulse at each 36th degree of rotation.
Patent Publication U.S. Pat. No. 5,610,339 teaches a method of evaluating and anticipating the conditions of a machine that includes at least one rotary element, with the aid of a vibration sensor (
12
) and a tacho-pulse sensor (
14
).
SUMMARY OF THE INVENTION
Technical Problems
When taking into consideration the technical deliberations that a person skilled in this particular art must make in order to provide a solution to one or more technical problems that he/she encounters, it will be seen that on the one hand it is necessary initially to realise the measures and/or the sequence of measures that must be undertaken to this end, and on the other hand to realise which means is/are required in solving one or more of said problems. On this basis, it will be evident that the technical problems listed below are highly relevant to the development of the present invention.
It will be understood that by the term tacho-signals as used in the following description is meant the tacho-signals that are generated or formed internally in the measuring equipment and that are required for evaluation of the measuring result. These tacho-signals have a higher frequency than tacho-signal initiating pulses, abbreviated to tacho-pulses, this expression being understood as meaning tacho-signals that are formed via a tacho-pulse receiving and controlling sensor.
When considering the present state of the art as described above, it will be evident that a technical problem resides in creating with a starting point from the basic features of the known technology conditions which will enable the measuring equipment to create conditions, with the aid of simple means, so as to obtain the tacho-signals generated in internal circuits and necessary to the measuring process through the medium of signal processing and by increasing the frequency of received tacho-pulses, in addition to evaluating prevailing sound and other vibrations generated by a rotating object, such as an electric motor, a petrol-driven or diesel-driven engine, and like machines as well as driven rotating objects, such as pumps, separators and like objects.
Another technical problem is one of enabling well-defined tacho-signals to be obtained with the aid of simple means, even in respect of objects that have not been provided with means for generating a large number of tacho-pulses during one revolution of the rotating object (such as a cogwheel), but which, nevertheless, have a readily accessible rotatable surface part, such as an exposed rotatable shaft or axle.
Another technical problem resides in realising the advantages that are afforded by applying to an accessible, rotatable surface-part one or more markings, preferably only one single marking, for generating tacho-pulses, and sensing said marking/s as it passes a few, preferably one, sensor while, nevertheless, sending to the measuring equipment a far greater number of tacho-signals for calculating purposes, through the medium of internal circuitry. Another problem in this respect resides in realising the means required to this end.
Another technical problem is one of realising the significance of and the advantages afforded by enabling an electronic unit to divide the time distance between two mutually sequential tacho-pulses into a predetermined number of sub-section, each having mutually the same duration, and generating a pulse-like tacho-signal with each such sub-section.
Another technical problem is one of realising the significance of and the advantages afforded by observing that the duration of the sub-sections can be varied in response to the speed at which the object rotates.
Yet another technical problem is one of realising the significance of and the advantages afforded by selecting only a few tacho-pulses for each revolution, say one pulse per revolution, and causing the circuit-internal electronics to perform the necessary, uniform division of the time distance between the tacho-pulses.
Another technical problem is one of realising the significance of allowing the number of time divisions, and therewith the number of tacho-signals per revolution, to be sixteen or thirty-two and therewith simplify signal processing in the computer unit.
A particular technical problem resides in realising the significance of and the advantages afforded by utilising a calculated duration for each sub-section evaluated between a firs
Banner & Wittcoff, Ltd.
Miller Rose M.
Williams Hezron
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