BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic drawing showing the first embodiment of a vacuum pump according to the present invention, and shows an outline structure of a pump main body and a controller of a magnet-bearing type turbo-molecular pump;
FIGS. 2(
a) and 2(b) are drawings showing a relationship between a nut 42 and a gap sensor 44, wherein FIG. 2(a) is a perspective view, and FIG. 2(b) is a plan view of the nut 42 viewed from a gap sensor 44 side;
FIG. 3 is a block diagram showing details of a gap sensor 44 and a detecting portion 31;
FIGS. 4(
a) and 4(b) are graphs showing the changes of the magnetic permeability or an inductance relative to a temperature of a magnetic body, wherein FIG. 4(a) shows a change of temperature of the magnetic permeability, and FIG. 4(b) shows a change of the inductance;
FIGS. 5(
a) and 5(b) are timing charts showing examples of a signal output from a detection and rectification portion 313, wherein FIG. 5(a) shows a situation wherein a temperatures T of targets 81, 82 is T<Tc, and wherein FIG. 5(b) shows a case wherein the temperature T of the targets 81, 82 is T>Tc;
FIGS. 6(
a) to 6(c) are charts, wherein FIG. 6(a) shows dispersion of sensor outputs, FIG. 6(b) shows that multiple sensor outputs of a magnetic body part are overlapped, and FIG. 6(c) shows a signal after averaging processing;
FIG. 7 is a block diagram showing a structure of the detecting portion 31 in the case wherein the detection and rectifying processing are omitted;
FIGS. 8(
a)-8(g) are graphs showing examples of signal waveforms;
FIGS. 9(
a)-9(f) are waveforms depicting sampling timings;
FIG. 10 is a graph explaining a sampling wherein fs=fc;
FIG. 11 is a block diagram showing details of the gap sensor 44 and the detecting portion 31 according to a second embodiment;
FIGS. 12(
a) to 12(c) are graphs, wherein FIG. 12(a) show signals before the removal of a finite difference, FIG. 12(b) is a graph showing a differential signal, and FIG. 12(c) is a graph showing a derivative signal;
FIGS. 13(
a) and 13(b) are drawings showing a modified example of a nut used in accordance with a second embodiment, wherein FIG. 13(a) is a perspective view of the nut 42, and FIG. 13(b) is a plan view of the nut 42;
FIGS. 14(
a) and 14(b) are graphs showing the sensor outputs in accordance with the modified nut example shown in FIGS. 13(a) and 13(b), wherein FIG. 14(a) shows a case of the T<Tc, and FIG. 14(b) shows a case of the T>Tc;
FIG. 15(
a) is a graph showing a relationship between gap volume between the gap sensor 44 and the targets, and the sensor outputs, and FIG. 15(b) is a graph showing a correction coefficient; and
FIGS. 16(
a) and 16(b) are graphs showing changes of the outputs by the change of the magnetic permeability, wherein FIG. 16(a) shows the sensor output in a dot P1, and FIG. 16(b) shows the sensor output in a dot P2.
Patent Application
20070145929
