Wireless machine condition monitoring device

Abstract

A condition monitoring device configured to be mounted on a machine for sensing, for example, vibrations produced by the machine during operation, includes a base, a printed circuit board assembly lying in a first plane, and first and second fasteners, each having a longitudinal axis, lying in a second plane perpendicular to the first plane, the first and second fasteners extending through the printed circuit board assembly and into the base. A third plane is perpendicular to the first and second planes and is located halfway between the longitudinal axes of the first and second fasteners. An integrated power supply is connected to the printed circuit board assembly, and at least two active sensing cells, such as vibration sensors, are arranged symmetrically relative to the second plane and/or symmetrically relative to the third plane.

Claims

1. A condition monitoring device configured to be mounted on a machine, the condition monitoring device comprising: a base, a printed circuit board assembly including at least one printed circuit board lying in a first plane, a first fastener and a second fastener each having a longitudinal axis lying in a second plane perpendicular to the first plane, the first and second fasteners extending through the printed circuit board assembly and into the base, a third plane perpendicular to the first plane and perpendicular to the second plane being located halfway between the longitudinal axes of the first and second fasteners, an integrated power supply connected to the printed circuit board assembly; and a sensor mounted to the at least one printed circuit board, the sensor comprising at least two active sensing cells arranged symmetrically relative to the second plane.

2. The condition monitoring device according to claim 1, wherein the at least two active sensing cells are intersected by the third plane.

3. The condition monitoring device according to claim 1, wherein the at least two active sensing cells are bisected by the third plane.

4. The condition monitoring device according to claim 1, wherein the at least two active sensing cells are arranged symmetric relative to the third plane.

5. The condition monitoring device according to claim 1, wherein a lower part of the printed circuit board assembly extends downward beyond the battery, and wherein the first fastener and the second fastener extend through the lower part of the printed circuit board assembly.

6. The condition monitoring device according to claim 5, wherein the base comprises: a first fixation portion configured to be fixed to the machine, and a second fixation portion comprising a wall parallel to the first plane, wherein the lower part of the printed circuit board assembly is held against the second fixation portion by the first and second fasteners.

7. The condition monitoring device according to claim 1, wherein the at least two active sensing cells comprise at least three active sensing cells bisected by the third plane and arranged symmetric relative to the second plane.

8. The condition monitoring device according to claim 1, wherein the at least two active sensing cells comprise at least four active sensing cells bisected by the third plane and arranged symmetric relative to the second plane.

9. The condition monitoring device according to claim 1, wherein the at least two active sensing cells comprise a first active sensing cell, a second active sensing cell, a third active sensing cell and a fourth active sensing cell, wherein the first and second active sensing cells are located above the second plane, wherein the third and fourth active sensing cells are located below the second plane, wherein the first and third active sensing cells are located to a first side of the third plane, and wherein the second and fourth active sensing cells are located to a second side of the third plane.

10. The condition monitoring device according to claim 9, wherein the first and second active sensing cells are located equidistant from the third plane and the first and third active sensing cells are located equidistant from the second plane.

11. The condition monitoring device according to claim 1, wherein the printed circuit board assembly includes an antenna for wireless communication.

12. The condition monitoring device according to claim 1, wherein the first and second active sensing cells are piezoelectric elements or accelerometers.

13. The condition monitoring device according to claim 1, wherein the first and second active sensing cells are vibration sensors.

14. The condition monitoring device according to claim 1, wherein the second plane does not intersect a top edge of the at least one printed circuit board and does not intersect a bottom edge of the at least one printed circuit board.

15. A method for processing vibration signal received from the condition monitoring device according to claim 1, comprising: associating the vibration signals (S1, S2, S3) in the time domain provided respectively from the active sensing cells in order to obtain a resulting signal (S) in the frequency domain having an amplitude (S1+S2+S3) without noise; amplifying the resulting signal (S); and transmitting said amplified resulting signal to a data processor.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The present invention and its advantages will be better understood by studying the detailed description of specific embodiments given by way of non-limiting examples and illustrated by the appended drawings on which:

(2) FIG. 1 is an exploded perspective view of a condition monitoring device according to an embodiment of the invention.

(3) FIG. 2a is a front view of the monitoring device of FIG. 1.

(4) FIG. 2b is a front view of the monitoring device of FIG. 1, with two active cells in a single sensor unit.

(5) FIG. 3 is a cross-section of a monitoring device of FIG. 1.

(6) FIG. 4 is a cross-section of a monitoring device according to a second embodiment.

(7) FIG. 5 is a front view of a monitoring device according to a third embodiment.

(8) FIG. 6 is a front view of a monitoring device according to a fourth embodiment.

(9) FIG. 7 is a front view of the monitoring device according to a fifth embodiment.

(10) FIG. 8 is a front view of the monitoring device according to a sixth embodiment.

(11) FIG. 9 is a front view of the monitoring device according to a seventh embodiment.

(12) FIG. 10 is a front view of the monitoring device according to a eight embodiment.

(13) FIG. 11 is a schematic chart showing a signal processing method applied to the condition monitoring device according to FIG. 7.

DETAILED DESCRIPTION

(14) In the following description, the terms “longitudinal, “transversal”, “vertical”, “front”, “rear”, “left” and “right” are defined according to a usual orthogonal benchmark as shown on the drawings, which includes:

(15) a longitudinal axis X, horizontal and left to the right of front views;

(16) a transversal axis Y, perpendicular to the longitudinal axis X and extending from the rear to the front of front views; and

(17) a vertical axis Z, orthogonal to the longitudinal and transversal axis X and Y.

(18) FIGS. 1 to 4 illustrate an embodiment of a wireless machine condition monitoring device 10 according to the disclosure that is designed to be mounted on a rotating machine (not shown), for example on a housing of an electric motor, in the vicinity of a rolling bearing.

(19) The condition monitoring device 10 is configured to acquire raw vibration signals produced by the rotating machine, to amplify the signals, to process the signals with its data processor and to wirelessly transmit said vibration signals to a data center, for example via a gateway, in order to analyze the signals received and to determine the condition of the rotating machine.

(20) The condition monitoring device 10 comprises a base 12, for example made of metallic material, a printed circuit board assembly 14 (sometimes abbreviated “PCBA”) mounted on said base 12, an integrated power supply 16, such as for example a battery connected to the PCBA 14, a potting compound 17 surrounding the PCBA 14 and the battery 16 and a housing 18 covering and protecting the potting compound 17, the PCBA 14 and the battery 16.

(21) The housing 18 may be made from a material having high electromagnetic permeability, such as for example plastic, rubber or a resin.

(22) The potting compound 17 is, for example, made of a resin injected through through-holes 18a made on the housing 18 inside the inner volume 18b delimited in said housing 18. The potting compound 17 is injected until a level of potting 18a below the inner surface of the upper part of the housing, as shown for example on FIGS. 4 and 5. The level of potting 17a extend axially beyond the upper border of the PCBA 14.

(23) As illustrated, an antenna 19 is located in the upper part of the PCBA 14.

(24) The battery 16 is, for example, welded on the rear surface of the PCBA 14. However, the battery 16 may be fixed on the PCBA 14 by any other way.

(25) As illustrated, the printed circuit board assembly 14 comprises a first elongated printed circuit board 14a having a plate shape extending along a first axis Z, here vertical, and a second elongated printed circuit board 14b having a plate shape extending along the first axis Z. The second PCB 14b is mounted on a front surface of the first PCB 14a, opposite to the battery 16. In other words, the printed circuit boards are superposed along the transversal axis Y. The dimensions of the second PCB 14b are smaller than the dimensions of the first PCB 14a.

(26) Alternatively, the printed circuit board assembly 14 may comprise a single printed circuit board or more than two printed circuits boards.

(27) As illustrated for example in FIG. 1, the second PCB 14b has a particular configuration of holes 15a, 15b, 15c, which may include a round through-hole 15a used to avoid bubbles effect and add attaching points between the lateral faces of the PCB during a process of injecting a potting compound, such as for example a resin.

(28) The second PCB 14b further comprises two oblong through-holes 15b, 15c extending along the first axis Z and used to avoid any interference between tall components projecting from the first PCB 14a and the second PCB 14b. Said oblong through-holes also allows to contain enough potting compound. This particular oblong shape also gives some tolerance margin and act as attaching points between the lateral faces of the PCB during a process of injecting the potting compound.

(29) As can be seen on FIGS. 1 and 3, the printed circuit board assembly 14 has a vertical length greater than the length of the battery 16 so that the lower part 14c of said PCBA 14 extends vertically beyond the lower end 16a of the battery 16.

(30) The lower part 14c of the PCBA 14 is used to fix the PCBA 14 on the base 12.

(31) Therefore, the base 12 comprises a first fixation portion 12a designed to be fixed to the rotating machine. The first fixation portion 12a is substantially cylindrical. The base 12 further comprises a second fixation portion 12b extending along the first axis, here the vertical axis Z from the upper surface of the first fixation portion 12a.

(32) Said second fixation portion 12b has a partly frustoconical shape delimited by a plane mounting surface 12c configured to contact the rear surface of the lower part 14c of the PCBA 14. Alternatively, the second fixation portion 12b may be semi cylindrical (comprise a portion of a cylinder) with a plane mounting surface 12c.

(33) The PCBA 14 thus bears against said plane surface 12c and is fixed by two fixation elements 20, 21 spaced apart along a second axis, here the longitudinal axis X. The fixation elements 20, 21 extend along a third axis, here the transversal axis Y. For example, the fixation elements 20, 21 are screws configured to be fastened along a third axis, here the transversal axis Y. The fixation elements 20, 21 are located symmetrically relative to the vertical axis Z.

(34) The flatness of the fixation surface 12c is particularly important, since the flatter the fixation surface 12c, the better the vibration signal will be transmitted from the base to the PCBA 14. However, while important, the flatness of the fixation surface 12c is not essential to the invention.

(35) As can be seen on FIGS. 3 and 4, the fixation surface 12c is slightly offset compared to a central plane XZ comprising the vertical axis Z and the longitudinal axis X. However, in another embodiment shown on FIG. 5, the fixation surface 12c may be located in the plane XZ (on the central plane) comprising the vertical axis Z (first axis) and the longitudinal axis X (second axis).

(36) The base 12 thus allows a mechanical fixation of the PCBA 14 and allows vibration transfer of the moving machine to said PCBA 14.

(37) The condition monitoring device 10 further comprises a sensing element 30 configured to sense vibrations from the moving machine transmitted to the fixation surface 12c of the base 12.

(38) The sensing element 30 is mounted between the two fixation elements 20, 21. The two fixation elements 20, 21 are symmetrical compared to a symmetrical axis Z-Z passing through the center of the PCBA 14.

(39) As illustrated on FIGS. 1 to 4, the sensing element 30 comprises two active sensing cells 31, 32.

(40) Each of the active sensing cells 31, 32 may be mounted on an electronic component as shown on FIG. 2a or both active sensing cells 30, 31 may be mounted on a single electronic component as shown on FIG. 2b.

(41) The active sensing cells 31, 32 may be for example piezoelectric elements or an accelerometer.

(42) The two active sensing cells 31, 32 are fixed on the front surface of the lower part 14c of the PCBA 14, in order to be near the junction of the PCBA 14 and the base 12.

(43) According to the first embodiment shown in FIGS. 1 to 5, the two active sensing cells 31, 32 are arranged along the vertical axis Z passing through the symmetrical axis Z-Z of the fixation elements 20, 21 and are symmetrical relative to the longitudinal axis X.

(44) The embodiment shown in FIG. 6, in which identical parts are given identical references, differs from the previous embodiment in that the two active cells 31, 32 of the sensing element 30 are arranged along the longitudinal axis X passing through the fixation elements 20, 21 and are symmetrical relative to the vertical axis Z passing through the symmetrical axis Z-Z of the fixation elements 20, 21.

(45) The embodiment shown in FIG. 7, in which identical parts are given identical references, differs from the previous embodiment in that the sensing element 30 comprises three active cells 31, 32, 33 arranged along the vertical axis Z passing through the symmetrical axis Z-Z of the fixation elements 20, 21 and are symmetrical compared to the longitudinal axis X. The longitudinal axis X thus passes through one of the active cells 32.

(46) The embodiment shown on FIG. 8, in which identical parts are given identical references, differs from the embodiment of FIGS. 1 to 4 in that the sensing element 30 comprises four active cells 31, 32, 33, 34 arranged along the vertical axis and are symmetrical compared to the longitudinal axis X.

(47) The embodiment shown on FIG. 9, in which identical parts are given identical references, differs from the previous embodiment in that the four active cells 31, 32, 33, 34 of the sensing element 30 are arranged two by two along the vertical axis Z. A pair of active cells 31, 33 is symmetric with another pair of active cells 32, 34 compared to the vertical axis Z passing through the symmetrical axis Z-Z of the fixation elements 20, 21.

(48) The embodiment shown on FIG. 10, in which identical parts are given identical references, differs from the embodiment of FIG. 3 in that the printed circuit board assembly extend along a transversal axis Y (first axis) and fixed on said base, notably on a mounting surface 12d by two fastening elements 20, said fastening elements being spaced apart along a longitudinal axis X (second axis) and extending along a vertical axis (third axis) perpendicular to the transversal and longitudinal axes Y, X.

(49) In a general way, the printed circuit board assembly extending along a first axis, called “PCBA” and fixed on said base by two fastening elements, said fastening elements being arranged on a second axis and extending along a third axis perpendicular to the first and second axes.

(50) The first axis may be a vertical axis, the second axis may be a longitudinal axis and the third axis may be a transversal axis, as shown on FIGS. 1 to 9. Alternatively, the first axis may be a transversal axis, the second axis may be a longitudinal axis and the third axis may be a vertical axis, as shown on FIG. 10.

(51) In any way, the fastening elements extend along an axis perpendicular to the axis of extension of the PCBA.

(52) The fastening elements extend along an axis perpendicular to the mounting surface of the base.

(53) As can be seen in FIG. 11, a signal processing method 40 is applied to the condition monitoring device 10 according to the embodiment of FIG. 7, in which the sensing element 30 comprises three active cells 31, 32, 33. However, said signal processing method 40 may be applied to condition monitoring device according to any preceding embodiments.

(54) The vibration signals in the time domain S1, S2, S3 provided respectively from the active cells 31, 32, 33 are associated at step 41 in order to obtain a resulting signal S in the frequency domain having a better amplitude corresponding to the addition of the amplitudes of each signal S1, S2, S3, without the noise. Indeed, thanks to the specific arrangement of the active cells between the fixation elements and being symmetrical relative to the vertical axis passing through the symmetrical axis Z-Z of said fixation elements, only spatial synchronized vibration signals are added.

(55) At step 42, said resulting signal S is amplified and transmitted at step 43 to a data processor (not shown).

(56) The arrangement of the active cells thus allows an accurate vibration measurement to be obtained without distortions.

(57) Thanks to the disclosure, the vibration signals are amplified without increasing noise and distortion of the signal. It is thus possible to obtain more accurate information on the vibration of the moving machine.

(58) Representative, non-limiting examples of the present invention were described above in detail with reference to the attached drawings. This detailed description is merely intended to teach a person of skill in the art further details for practicing preferred aspects of the present teachings and is not intended to limit the scope of the invention. Furthermore, each of the additional features and teachings disclosed above may be utilized separately or in conjunction with other features and teachings to provide improved wireless machine condition monitoring devices.

(59) Moreover, combinations of features and steps disclosed in the above detailed description may not be necessary to practice the invention in the broadest sense, and are instead taught merely to particularly describe representative examples of the invention. Furthermore, various features of the above-described representative examples, as well as the various independent and dependent claims below, may be combined in ways that are not specifically and explicitly enumerated in order to provide additional useful embodiments of the present teachings.

(60) All features disclosed in the description and/or the claims are intended to be disclosed separately and independently from each other for the purpose of original written disclosure, as well as for the purpose of restricting the claimed subject matter, independent of the compositions of the features in the embodiments and/or the claims. In addition, all value ranges or indications of groups of entities are intended to disclose every possible intermediate value or intermediate entity for the purpose of original written disclosure, as well as for the purpose of restricting the claimed subject matter.