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EP-4314490-B1 - GEAR WEAR DETECTION IN INTERMESHING RUNNING GEARS

EP4314490B1EP 4314490 B1EP4314490 B1EP 4314490B1EP-4314490-B1

Inventors

  • SCHILLER, DIRK
  • SCHOENWALD, FREDDY

Dates

Publication Date
20260506
Application Date
20220329

Claims (15)

  1. A pair of intermeshing,oil-free running gears for dual- or multi-shaft vacuum pumps, comprising a first running gear (10) and a second running gear (20), characterized in that at least the first running gear (10) comprises a first gearwheel (11) and a second gearwheel (12), wherein the first gearwheel (11) and the second gearwheel (12) are axially arranged, and wherein the first gearwheel (11) comprises a predetermined number of first cogs (n11) of same dimension and the second gearwheel (12) comprises a predetermined number of second cogs (n12), wherein the predetermined number of second cogs (n12) is at least one, and the predetermined number of second cogs (n12) have a dimension smaller than the dimension of the predetermined number of first cogs (n11) to a predetermined amount (w), wherein the first gearwheel (11) is made of a material with a first elastic modulus (E) and the second gearwheel (12) is made of a material with a second elastic modulus (E'), and the first elastic modulus (E) and the second elastic modulus (E') are different.
  2. The pair of intermeshing running gears according to claim 1, wherein the predetermined amount (w) corresponds to the maximum permissible wear.
  3. The pair of intermeshing running according to claim 1 or 2, wherein the first gearwheel (11) and the second gearwheel (12) are arranged axially separated on the same shaft or in direct contact with each other.
  4. The pair of intermeshing running gears according to claim 1, wherein the material with the first elastic modulus (E) is one of polymer and the material with the second elastic modulus (E') is one of metal.
  5. The pair of intermeshing running gears according to any of the claims 1 - 4, wherein the predetermined number of second cogs (n12) is greater than one and less than the predetermined number of first cogs (n11).
  6. A vacuum pump system, comprising a dual- or multi-shaft vacuum pump and the pair of intermeshing oil-free running gears according to any of the claims 1 - 5, characterized in that the dual- or multi-shaft vacuum pump (30), comprises a motor (31), a first shaft (32) and at least one second shaft (33), wherein the first shaft (32) and the second shaft (33) are synchronously driven by the motor (31) preferably via a common drive belt (34), wherein the first shaft (32) has a pumping element (321) and the second shaft (33) has a pumping element (331) which cooperates with the pumping element (321) of the first shaft (32) in order to convey a gaseous medium from an inlet (35) to an outlet, wherein the first shaft (32) comprises the first running gear (10) and the second shaft (33) comprises the second running gear (20).
  7. The system according to claim 6, wherein in a first mode of operation (m1) the second running gear (20) is in direct contact only with the first gearwheel (11), and wherein in a second mode of operation (m2) the second running gear (20) is in direct contact with the second gearwheel (12), when the dimension of the first gearwheel (11) is reduced by the predetermined amount (w) due to material wear, and wherein a first frequency spectrum (f1) of the sound produced by the first running gear (10) and the second running gear (20) during the first mode of operation (m1) is different from a second frequency spectrum (f2) of the sound produced by the first running gear (10) and the second running gear (20) during the second mode of operation (m2).
  8. The system according to claim 6 or 7, wherein during normal operation the running gears (10, 20) are not in contact with each other.
  9. An apparatus, comprising the vacuum pump system according to any of claim 6 - 8 and further comprising a gear wear detection device, characterized in that the gear wear detection device (40) comprises a detection module (41) configured to detect the sound produced by the running gears (10, 20), and further comprises an analysis module (42) configured to analyze the frequency spectrum of the detected sound, and further comprises a determination module (43) configured to determine a wear of the running gears (10, 20) dependent on a change of the analyzed frequency spectrum.
  10. The apparatus according to claim 9, wherein the determination module (43) is configured to determine if the analyzed frequency spectrum is equal to the frequency spectrum (f2) produced by the running gears (10, 20) in the second mode of operation (m2).
  11. The apparatus according to claim 9 or 10, wherein the gear wear detection device (40) further comprises a displaying module (44) configured to display a gear wear notification to the user if the analyzed frequency spectrum is equal to the second frequency spectrum (f2) produced by the running gears (10, 20) in the second mode of operation (m2).
  12. The apparatus according to any of the claims 9 - 11, wherein the gear wear detection device (40) is a mobile terminal (50).
  13. A method for gear wear detection in intermeshing oil-free running gears according to any of the claims 1 - 5, characterized in that the method comprises: detecting (S1) the sound produced by the running gears (10, 20), analyzing (S2) the frequency spectrum of the detected sound, and determining (S3) a wear of the running gears (10, 20) dependent on a change of the analyzed frequency spectrum.
  14. The method according to claim 13, wherein the determining (S3) comprises: determining if the analyzed frequency spectrum is equal to the frequency spectrum (f2) produced by the running gears (10, 20) in the second mode of operation (m2).
  15. The method according to any of the claims 13 or 14, wherein the method further comprises: displaying (S4) a gear wear notification to the user if the frequency spectrum is equal to the frequency spectrum (f2) produced by the running gears (10, 20) in the second mode of operation (m2).

Description

The present invention relates to a pair of intermeshing oil-free running gears for dual- or multi-shaft vacuum pumps. Further, the present invention relates to a vacuum pump system comprising a pair of intermeshing oil-free running gears and an apparatus, comprising such a vacuum pump system and further comprising a gear wear detection device. Further, the present invention relates to a method for gear wear detection in intermeshing running gears of a dual- or multi-shaft vacuum pumps. Known gear wear detection in intermeshing oil-free running gears involves the inspection of gear components and the measurement of gear wear parameters, which usually requires an interruption of operation and partial disassembly of the machine comprising the running gears. One disadvantage of known solutions for gear wear detection are high costs caused by the interruption of operation and the inspection of the machine comprising the running gears. Other disadvantages include complex disassembly and reassembly of machine parts and even potential failure of the machine comprising intermeshing oil-free running gears if gear wear is not detected in time. WO2020/007665 describes a multi-shaft vacuum pump comprising intermeshing gears according to the prior art. An object of the present invention is to provide an efficient and reliable solution for gear wear detection in intermeshing running gears, thereby overcoming the disadvantages of the prior art. The object is achieved by the pair of intermeshing preferably oil-free running gears in particular for dual- or multi-shaft vacuum pumps according to claim 1; the vacuum pump system, comprising a dual- or multi-shaft vacuum pump and a pair of intermeshing preferably oil-free running gears according to claim 6; the apparatus, comprising a vacuum pump system and further comprising a gear wear detection device according to claim 9; and the method for gear wear detection in intermeshing preferably oil-free running gears according to claim 13. The pair of intermeshing running gears for dual- or multi-shaft vacuum pumps according to the invention comprises a first running gear and a second running gear meshing with each other, wherein at least the first running gear comprises a first gearwheel and a second gearwheel. The first and the second gearwheel of the first running gear are axially arranged. In this way the two gearwheels of the first running gear build a single running gear configured to mesh with the second running gear. Therein, preferably, the intermeshing running gears are operated oil-free. According to the invention, the first gearwheel comprises a predetermined number of first cogs of the same dimension and the second gearwheel comprises a at least one second cog, wherein the second cog has a dimension smaller to a predetermined amount than the dimension of the first cogs. The first and the second cogs provide contact surfaces for the second running gear as the first and the second running gears are designed in an intermeshing manner. Preferably, the differences in dimension of the first and second cogs to a predetermined amount w concern those parts of the first and the second cogs that are in direct contact, when the first and the second running gears are meshing. Further, according to the invention the first gearwheel is made of a material with an elastic modulus different than the elastic modulus of the material of the second gearwheel. As the first gearwheel is made of a material with an elastic modulus different than the elastic modulus of the material of the second gearwheel, the acoustic properties of the first and the second gearwheel, respectively will be different. In particular, the acoustic frequency spectrum of the sound produced by the second running gear being in contact with the first gearwheel will be distinct from the acoustic frequency spectrum of the sound produced by the second running gear being in contact with the second gearwheel. This may have the advantage that via the detected differences in the acoustic frequency spectra gear wear can be detected. Preferably, the predetermined amount to which the dimension of the second cogs are smaller than the dimension to the first cogs corresponds to the maximum permissible wear. This may have the advantage that only upon the maximum allowable wear is reached, the second cogs come into contact with the cogs of the second running gear and before the maximum admissible wear is reached, only the first cogs of the first gearwheel will be in contact with the cogs of the second running gear. For both situations a characteristic sound is generated suitable to determine wear of the gear. Preferably, the first gearwheel and the second gearwheel are arranged axially separated on the same shaft or in direct contact with each other. Preferably, the first gearwheel and the second gearwheel are designed in sandwich-construction, such that the second gearwheel adheres permanently to the first gearwheel. Preferably, the mat