Radiant energy – Photocells; circuits and apparatus – Optical or pre-photocell system
Patent
1986-01-22
1988-02-16
Nelms, David C.
Radiant energy
Photocells; circuits and apparatus
Optical or pre-photocell system
356400, 250201, G01N 2186
Patent
active
047257385
DESCRIPTION:
BRIEF SUMMARY
The invention relates to an apparatus for detecting changes in the relative position of separately mounted machines. A relative change in the positions of machines mounted with a space between them may frequently lead to critical operational situations. This is for example the case with rotating machinery, whose shafts are coupled together. Such machines are aligned in relation to each other before being put into operation and every change in the relative alignment taking place during use may lead to serious damage to the bearings and possibly other parts of the machines. So far such machines have been inspected in of different ways, as for example by constantly sensing the alignment of the shafts by using measuring fittings mounted on the shafts, by continuous measurement of the bearing temperature and by continuous measurement of vibrations of the machines.
The object of the invention is to inspect machines which have a critical position in relation to each other by continuously ascertaining their postions as related to their initial position. More specifically, the aim of the invention is to devise an apparatus for this purpose which is characerized by accuracy of measurement while being simple in design and capable of indicating both parallel and angular misalignments.
The invention takes advantage of the particular optical properties of reflecting prisms or similar optical systems.
The invention takes advantage of the property of a reflecting prism or similar optical system by which a ray reflected from a prism on the incidence of a highly collimated light ray approximately perpendicular to the hypotenuse plane of the prism changes in direction if the prism is revolved about an axis through the apex and parallel to the hypotenuse plane and that this change in direction leads to a displacement of the point of incidence of the reflected light ray on a plane approximately perpendicular to the said ray in a direction which is perpendicular to the direction in which the point of incidence moves in the case of a displacement of the prism or the like parallel to the apical line. The orientation of the prisms in accordance with the invention ensures that at the light transmitter the parallel offset component and the angular offset component of any change in position of the machines in relation to each other in a direction towards or around, one of the axes of the spatial coordinate system may be clearly distinguished as separate components as well, since they may be read off along rectangular coordinates of the displacement of the point of incidence of the light ray from a given reference point.
In cases in which relative alignment of the machines to be inspected is only critical in two coordinate directions, the inspection of the third coordinate direction may be considered unnecessary. In this case the invention offers the advantage of corresponding reduction of structural complexity by having one less prism or the like with its respective light transmitter and light receiver.
The invention will now be described in more detail having reference to the drawings and on the basis of one embodiment.
FIGS. 1 and 2 show a reflecting prism diagrammatically from the side and from above, respectively;
FIG. 3 show two rotary machines equipped with the apparatus of the invention with coupled shafts, as seen in a perspective view;
FIGS. 4 and 5 show a preferred embodiment of the light transmitter used for the machines in FIG. 3 diagrammatically in plan and from the front, respectively;
FIG. 6 shows a schematic cross-section of a form of the light receivers on the machine set-up in accordance with FIG. 3 in the form of a photelectric semi-conductor position detector;
FIG. 7 shows the postion detector as in FIG. 6 in a dual-axis form, from the front;
FIG. 8 is a cross section through the detector as in FIG. 7 on the line V--V.
FIGS. 1 and 2 show a rectangular reflecting prism 1 in different positions.
If an incoming and preferably highly collimated light ray L strikes the prism 1 perpendicularly to the hypotenuse plane H,
REFERENCES:
patent: 2703505 (1955-03-01), Senn
patent: 3923402 (1975-12-01), Turcotte
patent: 4097157 (1978-06-01), Lill
patent: 4518855 (1985-05-01), Malak
Fiddler Robert W.
Nelms David C.
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