Measuring and testing – Liquid analysis or analysis of the suspension of solids in a... – Viscosity
Patent
1999-01-20
2000-11-28
Williams, Hezron
Measuring and testing
Liquid analysis or analysis of the suspension of solids in a...
Viscosity
73 5432, 73 5303, G01N 1102, G01N 1116
Patent
active
06151957&
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention concerns a device according to the preamble of claim 1.
BACKGROUND OF THE INVENTION
Such devices are previously known and are applied in different areas of technology. It is thus previously known to measure the mass concentration in a paper pulp suspension by measuring a resisting torque when rotating a sensor in the suspension to be investigated. The measured torque is based on the force exerted by the rotating body for separating fibres in the suspension. The force and thus the torque thus depends of the quantity of fibres in the suspension. It is further previously known to avoid stuff box friction etc. by leading the rotating shaft which transmits the torque through a hollow shaft and use a sensor functioning according to the principle of equilibrium of forces. This principle is based on the fact that because of an exerted torque, a displacement will occur between the transmitting shaft and the hollow shaft which displacement may be detected. Known measuring methods suffer however from disadvantages with respect to errors in measurement, i. a. due to the connection between the sensor shaft and the hollow shaft. Also in other respects the known measuring methods are unreliable.
It should be noted that the consequences of measurement errors can be substantial. As an example in paper manufacture, if a paper pulp suspension is to be investigated, the economically acceptable concentration interval ranges in a variation of dry contents of only about one percent. Too low concentration may lead to breakage of the resulting paper web, too high concentration results in waste of fibre and too thick paper.
SUMMARY OF THE INVENTION
It is an aim of this invention to eliminate the disadvantages of the previously known solutions and to provide a reliable, accurate economic solution.
This aim is obtained in a device according to the above by the features of the characterizing portion of claim 1.
Hereby it is achieved that the oscillating frequency of a related element, the frequency of which being representative of the torque, is directly detectable by a detector which is placed outside the transmission, which considerably enhances the accuracy as well as the reliability of the device. This firstly because a frequency transmitting element is employed in the sensor device with a minimum of sources of error, and secondly because a frequency signal, which is transmitted from the detector, is considerably more unsensitive to different types of disturbances than is the case of an analog signal. The advantages of using a frequency signal is i.a. that such a signal is uninfluenced by electrical fields around for example electrical power cables which often are located in proximity to the signal cable.
U.S. Pat. No. 3,290,930 is mentioned as an example of comparison wherein, however, a frequency signal which characterizes the torque is transmitted with the aid of a radio transmitter-receiver. Also SE-D-380 899 concerns the use of frequency signals wherein however, this document concerns electronic monitoring of these frequency signals and thus not the location of the detector. In a device according to this invention there are no electrical signals transmitted from the moving parts.
By the sensor device comprising a ring-shaped element carrying a frequency gauge a preferred fastening thereof is obtained.
The features of the claims 3-6 concerns preferred features with respect to the location of the elements of the sensor device.
The claims 9 and 10 concerns preferred locations of the frequency gauge. In that regard, the frequency gauge can be band-shaped. The frequency gauge can also be curved between its ends, which can be fixed.
Further advantages are obtained according to the other claims.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will no be described in greater detail with reference to the accompanying drawings, wherein:
FIG. 1 diagrammatically shows a measuring device according to the invention,
FIG. 2a shows a section of a device according to the invention in the area of
REFERENCES:
patent: 722576 (1903-03-01), Grand
patent: 2807160 (1957-09-01), Asbeck
patent: 3126735 (1964-03-01), Vogttle et al.
patent: 3181349 (1965-05-01), Jansson
patent: 3239325 (1966-03-01), Roberson et al.
patent: 3285058 (1966-11-01), Ostroot
patent: 3290930 (1966-12-01), Drinkwater
patent: 3722262 (1973-03-01), Gilinson, Jr. et al.
patent: 4129031 (1978-12-01), Tehon et al.
patent: 4175425 (1979-11-01), Brookfield
patent: 5301541 (1994-04-01), Joseph et al.
patent: 5677481 (1997-10-01), Brown et al.
patent: 5948970 (1999-09-01), Te'eni
Knut Enarson AB
Senterfitt Akerman
Wiggins David J.
Williams Hezron
LandOfFree
Measuring device comprising an excitable frequency gauge does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Measuring device comprising an excitable frequency gauge, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Measuring device comprising an excitable frequency gauge will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1713464