Abstract
Disclosed is an electric motor with a stator, a rotor rotatably mounted relative to the stator and motor electronics. The motor electrics is arranged in an electronics housing and mounted on a circuit board. On the circuit board there is arranged at least one vibration sensor configured for measuring an acceleration and/or speed of vibrations of the electric motor in at least one direction. In addition, said circuit board is vibrationally coupled with other components of the electric motor using at least one coupling element, so that at least parts of the vibrations of the electric motor are transmitted to the vibration sensor. Furthermore, a fan is disclosed, including an electric motor and an impeller. A method for evaluating a vibration state of an electric motor is disclosed, wherein said electric motor can be formed by an electric motor as also disclosed herein.
Claims
1-17. (canceled)
18. An electric motor comprising: a stator; a rotor rotatably mounted relative to the stator; motor electronics located in a housing and mounted on a circuit board; and at least one vibration sensor disposed on the circuit board, the at least one vibration sensor configured to measure at least one of an acceleration and speed of vibrations of the electric motor in at least one direction, wherein the circuit board is vibrationally coupled to other components of the electric motor via at least one coupling element such that vibrations of the electric motor are transmitted to the at least one vibration sensor.
19. The electric motor of claim 18, wherein the housing comprises a bottom and sidewalls.
20. The electric motor of claim 19, wherein the at least one vibration sensor is disposed on a side of the circuit board facing the bottom of the housing.
21. The electric motor of claim 19, wherein the bottom of the housing comprises a protrusion adjacent to the at least one vibration sensor so that a distance between the at least one vibration sensor and the housing is reduced proximate to the protrusion.
22. The electric motor of claim 18, wherein the at least one coupling element is made from plastic.
23. The electric motor of claim 18, wherein the at least one coupling element comprises a casting compound filling at least part of a region between the housing and the circuit board.
24. The electric motor of claim 23, wherein the casting compound is divided into a first casting compound and a second casting compound by a partition wall, the second casting compound having a lower elasticity than the first casting compound and the second casting compound disposed adjacent to the at least one vibration sensor.
25. The electric motor of claim 18, wherein the at least one coupling element comprises an adhesive pad or an adhesive.
26. The electric motor of claim 18, wherein the at least one coupling element comprises a plastic overmold attached to the electric motor, wherein the at least one vibration sensor is in direct contact with the plastic overmold.
27. The electric motor of claim 18, wherein the at least one coupling element comprises a fastener, the fastener selected from the group consisting of a screw, a rivet, a clamp, a dowel pin and a grooved nail, wherein the fastener is disposed proximate to the at least one vibration sensor.
28. The electric motor of claim 18, wherein the housing is integral with a stator bushing of the electric motor.
29. The electric motor of claim 18, wherein the electric motor comprises an electronically commutated motor.
30. The electric motor of claim 18, wherein the housing comprises a bottom and sidewalls and at least one of the bottom and the sidewalls are coated with plastic.
31. A fan comprising: an impeller; and the electric motor of claim 18, wherein the impeller is connected to the rotor.
32. A method for evaluating a vibration state of the electric motor of claim 18, the method comprising: generating a measurement signal using the at least one vibration sensor, wherein the at least one vibration sensor is configured for measuring at least one of an acceleration and speed of vibrations of the electric motor in at least one direction; determining at least one of an amplitude, a phase, and a frequency of the measurement signal to determine at least one vibration parameter representing the vibrations of the electric motor; comparing the at least one vibration parameter with a corresponding reference parameter; and determining a vibration state of the electric motor based on the comparison of the at least one vibration parameter with the corresponding reference parameter.
33. The method of claim 32, wherein based on the determined state of vibration, further comprising at least one of: generating a warning message; and initiating measures to protect the electric motor.
34. The method of claim 32, wherein prior to comparing the at least one vibration parameter with the corresponding reference parameter, evaluating whether the at least one vibration parameter exceeds a predefined limit value.
Description
[0057] There are now various possibilities for configuring and developing the teachings disclosed herein in an advantageous manner. For this purpose, on the one hand, reference is made to the claims depending on the independent claims and, on the other hand, to the following explanation of exemplary embodiments with reference to the drawings. In connection with the explanation of the exemplary embodiments with reference to the drawings, generally preferred configurations and further developments of the teaching are also explained. In the drawings:
[0058] FIG. 1 shows a section through a first exemplary embodiment of an electric motor, a screw and a casting compound being used as coupling elements,
[0059] FIG. 2 shows a section through a second exemplary embodiment of an electric motor similar to the first exemplary embodiment, wherein additionally the bottom and the side walls of electronic housing are coated with a plastic,
[0060] FIG. 3 shows a section through a third exemplary embodiment of an electric motor, wherein the bottom of the electronics housing has a protrusion in the area of the vibration sensor,
[0061] FIG. 4 shows a section through a fourth exemplary embodiment of an electric motor, wherein the bottom and parts of the side walls of the electronics housing are covered with a plastic and wherein only in a partial area between the bottom of the electronics housing and the circuit board a casting compound is used as a coupling element,
[0062] FIG. 5 shows a section through a fifth exemplary embodiment of an electric motor, a screw, a casting compound and an adhesive pad being used as coupling elements,
[0063] FIG. 6 shows a section through a sixth exemplary embodiment of an electric motor, wherein a casting compound is divided into a first and a second casting compound by a partition wall,
[0064] FIG. 7 shows a section through a seventh exemplary embodiment of an electric motor, a screw and a plastic overmold being used as coupling elements,
[0065] FIG. 8 shows a section through an eighth exemplary embodiment of an electric motor, a plastic overmold being used as the coupling element,
[0066] FIG. 9 shows a diagram with exemplary profiles of a vibration value at different rotational speeds and during measurement of the vibration sensors in different directions, and
[0067] FIG. 10 shows a flow diagram of an exemplary embodiment of a method.
[0068] All of the exemplary embodiments of electric motors illustrated in the figures are each constructed in an external rotor configuration. This means that the stator is arranged at the motor axis and the rotor is arranged around the stator. For the sake of clarity, the rotor of the electric motor is not illustrated in each of the figures. This does not mean—of course—that the electric motor does not have a rotor.
[0069] FIGS. 1 to 6 in each case illustrate a section through a stator 2 of an electric motor 1. A bearing tube 4 is formed at a motor axis 3, at the longitudinal ends of which a bearing receiving area 5 is formed in each case. The bearing receiving areas 5 are accommodating bearings not illustrated, to which a shaft of the electric motor, not illustrated, is rotatably mounted. A stator bushing 6 is formed from an aluminum component, at the one end of which the bearing tube 4 is formed and at the other end of which an electronic housing 7 is formed for accommodating a motor electronics. The electronics housing 7 has a bottom 8 and side walls 9. The motor electronics generates supply signals and outputs them to the stator and/or rotor windings. For the sake of clarity, FIGS. 1 to 6 only show a circuit board 10 of the motor electronics. In the following, the side of the circuit board 10 facing the bottom 8 is referred to as the bottom side 11 and the side of the circuit board 10 facing away from the bottom 8 is referred to as the top side 12. The various exemplary embodiments of the electric motor illustrated in FIGS. 1 to 6 differ in the arrangement of the vibration sensor 13 on the circuit board 10 and the coupling elements used in each case.
[0070] In the exemplary embodiment of FIG. 1, the vibration sensor 13 is arranged on the top side 12 of the circuit board 10. The circuit board 10 is embedded in a casting compound 14, 15, wherein the casting compound 14, 15 is connected at the edge area of circuit board 10. In this case, the part of the casting compound 14 enclosed between the bottom 8 and the bottom side 11 of circuit board 10 functions as a coupling element and transmits vibrations from the stator bushing 6 through the bottom 8 of the electronics housing 7 to the circuit board 10 and thus to the vibration sensor 13. A screw 16 is provided as a further coupling element, which is screwed into a bore 17 in the electronics housing 7. In the exemplary embodiment illustrated, the screw is arranged close to the vibration sensor 13 and thus ensures also that vibrations are transmitted from the stator bushing 6 to the circuit board 10 via the screw 16, and thus to the vibration sensor 13.
[0071] The exemplary embodiment of FIG. 2 is very similar to the exemplary embodiment of FIG. 1. In addition, however, a plastic coating 18 is attached to the bottom 8 and to parts of the side wall 9 of the electronics housing. This plastic coating 18 provides additional electrical insulation, but also transmits vibrations of the electric motor, in this case, vibrations from the bottom 8 of the electronics housing 7 to the casting compound 14. Therefore, even this plastic coating 18 can form a coupling element.
[0072] In the exemplary embodiment of FIG. 3, the vibration sensor 13 is arranged at the bottom side 11 of circuit board 10. In this exemplary embodiment, a casting compound 14, 15, a screw 16 and a plastic coating 18 are used as coupling elements. In order to reduce the distance between the bottom 8 of the electronics housing 7, a protrusion 19 is formed in the area of the vibration sensor 13. Said protrusion 19 is slightly wider than the extent of the vibration sensor 13 and is planar on the top side. Between protrusion 19 and vibration sensor 13 there is still some casting compound 14 and the plastic coating 18.
[0073] A partition wall 20 is formed in the embodiment of FIG. 4, which, in the exemplary embodiment illustrated, is formed integrally with a plastic lining 28. The plastic lining 28 covers—similar to the plastic coating 18 in FIG. 2 or 3—the bottom 8 and parts of the side wall 9. The partition wall 20 separates an area in which a casting compound 14 is arranged as a coupling element. The other areas between circuit board 10 and bottom 8 and the area above the circuit board 10 are not filled with casting compound. As a further coupling element there is again a screw 16 which is arranged close to the vibration sensor 13. In this exemplary embodiment, the screw 16 is placed between the motor axis 3 and the vibration sensor 13.
[0074] The exemplary embodiment of FIG. 5 includes, as coupling elements, a casting compound 14, 15 and a screw 16. Moreover, a protrusion 19 is formed at the bottom 8, which protrusion reduces the distance between the bottom 8 and the vibration sensor 13. In addition, an adhesive pad 21 is arranged as a further coupling element, which fills the area between the vibration sensor 13 and protrusion 19 and establishes a further vibrational coupling between the vibration sensor 13, the circuit board 10 and other components of the electric motor.
[0075] In FIG. 6, again, a partition wall 20 is provided, which in this case divides the casting compound between the bottom 8 and the circuit board 10, in a first casting compound 22 and a second casting compound 23. In this case, the second casting compound 23 has a lower elasticity than the first casting compound 22, so that the second casting compound 23 is “harder” than the first casting compound 22. In this way, the second casting compound 23 will establish a better coupling between vibration sensor 13 and other components of the electric motor, which is expressed by better transmission of higher frequencies.
[0076] FIG. 7 illustrates another exemplary embodiment of an electric motor. In this case, the electronics housing 7 is formed by an aluminum component 24 having a bottom 8 and side walls 9. In the bottom 8, holes (not illustrated) are formed through which a plastic overmold 25 can penetrate during an injection molding process. Said plastic overmold connects the stator 2 to the electronics housing 7 and is configured as a BMC (Bulk Molded Compound). The plastic overmold is in direct contact with the vibration sensor 13 and serves as a coupling element. In addition, there is a screw 16 as a further coupling element, which is screwed into a thread in the aluminum component 25.
[0077] A relatively similar configuration is shown in FIG. 8, in which case the electronics housing 7 has no aluminum component but the electronics housing 7 is formed by the plastic overmold 25 itself. Here, too, the plastic overmold 25 forms a coupling element, and the vibration sensor 13 is in direct contact with the plastic overmold. In addition, a cover 26 is illustrated closing an open side of the electronics housing. This cover 26 is connected to the plastic overmold by screws 27.
[0078] FIG. 9 shows a diagram with different signal profiles as they can arise on a vibration sensor of an electric motor. Such vibration sensor can, for example, be a vibration sensor 13 in an electric motor of the previously described exemplary embodiments. In this case, the three signal profiles illustrated represent exemplary measurement signals of a vibration sensor in three different directions. In this case, the three directions are respectively formed perpendicularly to each other. The solid line represents a measurement signal in a first sensor axis, the dashed line represents a measurement signal in a second sensor axis and the dotted line represents a measurement signal in a third sensor axis. The rotational speed is shown on the abscissa, and an amplitude of the measured value is shown on the ordinate. It can be seen that at different rotational speeds different signal profiles are formed in different sensor axes. These differences in different directions can be implemented in conjunction with a method, for example for one that is illustrated in FIG. 10.
[0079] FIG. 10 illustrates a flow diagram of an exemplary embodiment of a method according to some embodiments. In a first step 30, measured values of the sensors are collected in at least one direction. In this exemplary embodiment, measured values are collected in three directions/sensor axes. In step 31, these measured values are analyzed, and the amplitude, phase and frequency of the measurement signal are calculated. This results in parameters of the vibrations of the electric motor. In step 32, the calculated amplitude is compared to a reference amplitude. Provided that the amplitude of the measurement signals does not exceed a threshold value in all sensor axes, further processing is aborted and returned to a new data collection in step 30. If the amplitude of a measurement signal in a sensor axis exceeds the threshold value, the further steps are carried out.
[0080] In step 33, the determined measurement values and/or the calculated parameters are matched with vibrational states of known vibration modes, i.e., said determined parameters are compared with reference parameters, said reference parameters in each case having been recorded at known vibration modes. These reference parameters can come from a database, the content of which was created in a calibration measurement of the electric motor. Alternatively, the database can also contain reference parameters of a structurally identical or at least similar electric motor. From this it can be concluded which vibration state the electric motor is currently in.
[0081] In step 34, responsive to the identified vibration state, for example, the rotational speed is slightly reduced. In step 35 one waits until the changes have taken effect and the system has moved to a steady state. This usually happens within a few seconds to a few minutes. The method is then repeated at step 30 and a new data collection is carried out.
[0082] With regard to further advantageous configurations of the electric motor or of the method, to avoid repetitions, reference is made to the general part of the description and to the accompanying claims.
[0083] Finally, it should be explicitly noted that the above-described exemplary embodiments only serve to explain the claimed teaching, but do not limit it to the exemplary embodiments disclosed.
LIST OF REFERENCE NUMERALS
[0084] 1 electric motor (rotor not shown) [0085] 2 stator [0086] 3 motor axis [0087] 4 bearing tube [0088] 5 bearing receiving area [0089] 6 stator bushing [0090] 7 electronics housing [0091] 8 bottom [0092] 9 side wall [0093] 10 circuit board [0094] 11 bottom side [0095] 12 top side [0096] 13 vibration sensor [0097] 14 casting compound [0098] 15 casting compound [0099] 16 screw [0100] 17 bore [0101] 18 plastic coating [0102] 19 protrusion [0103] 20 partition wall [0104] 21 adhesive pad [0105] 22 first casting compound [0106] 23 second casting compound [0107] 24 aluminum component [0108] 25 plastic overmold [0109] 26 cover [0110] 27 fastening screws [0111] 28 plastic lining
