BE1029641B1 - AXIS ASSEMBLY - Google Patents

Abstract

An axle assembly comprising: a first axle (130) having a first axle end; a coupling member (200) fixedly attached to the first shaft end, the coupling member (200) configured to be fixedly attached to a second shaft end of a second shaft (112); and an electrically insulating member (204) coupled between the first shaft (130) and the coupling member (200) to thereby electrically isolate the first shaft (130) from the coupling member (200).

Description

AXIS ASSEMBLY

GESTED OF THE INVENTION

The present invention relates to shaft assemblies for use in vacuum pumping devices, compressors, & expanders and the like, and particularly to shaft assemblies for coupling two shafts together such that the two shafts are electrically isolated from each other.

BACKGROUND

Vacuum pumps are used in various technical processes to pump gases from process chambers thereby creating low pressure conditions for the respective processes. Positive displacement vacuum pumps include screw vacuum pumps, Rcots vacuum pumps, and the like, and are commonly used for evacuating a process gas from vacuum chambers in semiconductor manufacturing.

The positive displacement pumps usually comprise a pair of pontoon rotors mounted on rotor shafts and a motor comprising a motor shaft. The motor shaft of the motor is rigidly mounted on one of the rotor shafts, During operation the motor drives the rotors, Basically the motor shaft is rotated about its axis causing the rotor shafts and the rotors mounted on them to rotate within a pump chamber of the vacuum valve and suck in and discharge a gas,

SUMMARY OF THE INVENTION

The present inventors realized that for many vacuum pumps, including, but not limited to, oil-lubricated variable speed drive {VSD} rotary screw vacuum pumps, electrical current may flow through the bearings of that pump. The bearings of the pump rotatably support the rotor shafts to rotate the rotors within the container.

The present inventors further realized that electric current passing through the bearings of the pump often damages the bearings. Thus, it is desirable to prevent or reduce electric currents within the bearings of the pump. The present inventors further realized that electric currents within the bearings of the pump can usually be prevented or reduced by electrically isolating the rotor shafts and the motor shaft, or by improving electrical insulation therebetween, in one aspect there is provided an axle assembly comprising: a first axle having a first axle end; san coupling member fixedly attached to the first shaft end, the coupling member configured to be fixedly attached to a second shaft end of a second shaft; and an electrically insulating (or electrically resistive) member coupled between the first shaft and the coupling member for electrically isolating the first shaft from the coupling element. The shaft assembly may further include the second shaft, the second shaft having the second shaft end. The coupling element may be attached to the second shaft end of the second shaft The second shaft may be a shaft selected from the group of shafts consisting of a rotor shaft of a vacuum pump, a compressor or an expander and a motor shaft of a motor for driving a rctor shaft of a vacuum pump, a compressor or an expansion device.

The coupling element: may be an annular or tubular collar configured to fit around the second shaft end of the second shaft. The coupling element may be fixedly attached to the second shaft end of the first shaft by one or more fasteners. The one or more fasteners may be electrically isolated from one or both of the first shaft and clutch assembly,

The first shaft may include a flange at the first shaft end. The coupling member may be attached to the flange. The shaft assembly may further include one or more fasteners positioned through the flange from a first side of the flange to a second side of the flange. the flange opposite the first side of the flange,

The one or more fasteners may extend into the coupling member. The coupling element may be located on the second side of the flange. The shaft assembly may further comprise one or more further electrically insulating 158 elements disposed between one or more mounting means and the flange to thereby electrically separate one or more mounting means from the first shaft. insulating, The one or more further electrically insulating elements may comprise an annular electrically insulating element positioned about the first axis. The annular electrically insulating element may be on the first side of the flange.

The shaft assembly may further include an annular metal disc disposed against the annular electrically insulating 253 element. The one or more further electrical

Disclosing elements may include one or more electrically insulating washers, each electrically insulating washer disposed between the first side of the flange and a portion of one of the respective one or more fasteners. The axle assembly can also overturn one or more metal washers,

each metal washer in contact with one of the respective one or more electrically insulating washers and located between the first side of the flange and a head of one of the respective one or more fasteners, The electrically insulating member may be formed in a material selected from the group of materials comprising a ceramic material, aluminum oxide, and/or zirconium oxide, in a further aspect a vacuum pump, a compressor or an expansion device is provided = comprising: a vacuum pump, a COMCressor, or an expansion device with a rotor on a rotor shaft rotatably mounted in a housing; a motor with a motor shaft; wherein the motor shaft is coupled between the rotor shaft and the motor: the motor 18 is configured to rotate the motor shaft to thereby drive the rotor shaft; and the motor shaft and rotor shaft are electrically isolated from each other.

The assembly may further comprise a coupling member fixedly attached to one end of the molar shaft and one end of the rotor shaft, thereby fixedly securing the motor shaft and the rotor shaft together. The assembly may further comprise an electrically insulating element sandwiched between either the motor shaft and coupling element or the rotor shaft and coupling element. The motor shaft may include a lens located at the end of the motor shaft.

The assembly may further include: one or more fasteners positioned through the flange from a first side of the flange to a second side of the flange opposite the first side of the flange, the one or more fasteners extending into the coupling element, wherein the coupling element is on the second side of the flange; and one or more further electrically insulating elements located between the bond or more fasteners and the flange; the electrical & isciating element is located between the motor shaft and the ; coupling element; and the coupling element is an annular or tubular collar in which the end of the rotor shaft is received,

The vacuum pump can be a di-lubricated rotary screw vacuum pump.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a schematic illustration (not to scale) of a cross-sectional side view of a vacuum pumping device:

Figure 2 is a schematic illustration (not os scale) of sen cross-section in side view of sen

Coupling module of the vacuum pump device;: and

Figure 3 is a schematic illustration (not to scale) of a cross-sectional side view of another Klink module.

DETAILED DESCRIPTION

It should be understood that relative terms such as higher and lower, horizontal and vertical, above and below, front and back, etc. are used herein for ease of reference to the Figures only, and that such terms are not construed as such, and that any twes different directions or positions and so on can be implied instead of really higher and lower, horizontal and vertical, up and down, and so on.

Figure 1 is a schematic illustration (not to scale)

var 2 and cross-sectional side view of a vacuum pumping device 100 with a vacuum pump 102 and a motor 104,

In this embodiment, the vacuum pump 2102 is an oil-lubricated rotary screw vacuum pump.

In this embodiment, the motor 104 is an alternating current electric motor (AC). The MOTOFr 104 is configured to drive the vacuum sump 102. A variable frequency drive (VED) controller 48 (not shown) controls the frequency of the electrical current supplied to the motor. 104 is supplied. Consequently, the speed of the output shaft of the motor, and thus of the rotor of the vacuum pump 102, can be adjusted. The vacuum pump 102 as such is a variable speed drive (VSD) pump. The vacuum pong 102 includes a housing 106 defining a pump chamber 108, and a pair of intermeshed male and female screw rotors 110 rotatably mounted within the pump chamber 108. The screw rotors 110 are mounted on or integrated into the respective rotor shafts 112.

A gas inlet 114 is formed at one end of the housing 106. At another end of the housing 1056, opposite the end where the gas inlet 114 is located, is a gas outlet 116.

Formed on a first end portion of the pumping chamber 108 is a suction port 118, which is in fluid communication with the gas outlet 114, On a second end portion of the pumping chamber 108, opposite the first end portion, is formed a delivery port 120, which is in fluid communication with the gas outlet 116,

The rotor shafts 112 are at their first end portions,

i.e., as on their suction side, within a suction side bearing housing 122 rotatably supported by one or more first bearings 124. and/or angular contact ball bearings for forward thrust and/or backward thrust. The rotor shafts 112 are rotatably supported at their second end portions, i.e. at their discharge sides, in a

Bearing housing 125 on the discharge side by one or more second bearings 128. The second bearings 128 may include, for example, cylindrical roller bearings for radial loading, the outer ring of which is held in a predetermined position, and/or cam contact ball bearings for forward thrust loading and/or backward thrust loading .

The first end portion of one of the rotor shafts 112 (shown in Figure 1) is coupled for internal rotation to a motor shaft 130 of the motor 104. The motor shaft 130 can be considered an output or drive shaft of motor 104. The rotor shaft 112 and the motor shaft 130 are connected together by a coupling module 132,

The clutch module 132 is described in more detail below with reference to Figure 2. The motor shaft 130 may be rotatably supported, for example at the end close to the vacuum pump 102 by one or more third bearings. The third bearings can be, for example, cylindrical roller bearings for radial loading, the outer ring of which is held in a predetermined position, and/or angular contact ball bearings for forward thrust loading and/or backward thrust loading.

The propeller rotors 110 are in operation rotated by the motor 104. More specifically, the operation of the motor 104 causes the motor shaft 130 to be rotated on its axis, thereby rotating the rotor shaft 112 and the corresponding propeller rotor 3 110 attached thereto by the coupling module. 132, rotate. The rotational driving force is transmitted between the male and female rotors 110, for example by a synchronous transmission or by direct contact between the screw rotors 110. Rotation of the eighteen screw rotors 110 by the motor 104 causes gas to be drawn into the gas inlet 114 and through the suction port 118 into the pump chamber 108 in which the screw rotors 110 rotate. Due to the continued rotation of the sear rotors 110, the gas moves through the pump chamber 108, from the suction port 118 to the discharge port 120. The gas is then expelled from the discharge port 120, and through the gas outlet 116 is pushed out of the vacuum pump 102. in this embodiment, the vacuum pump 102 is a fly-lubricated pump. The vacuum port 102 further includes oil injection means (not shown) configured to inject oil into the housing 106. The oil may cause the screw rotors 110 to be sealed from the housing 106 and/or each other. . The oil may cool the propeller rotors 110 and/or the pumped gas. The oil may further provide lubrication and/or lubrication of the bearings 124, 128. The oil may be delivered via an oil flow path (not shown) to each of the

Bearings 124, 128 within the bearing housings 122, 126 on the suction and discharge sides are sealed. Figure 2 is a schematic illustration (not to scale) of a cross-sectional side view of a clutch module 132. The clutch module 132 is a module in which one end of the motor shaft 130 is fixedly mounted to an end of a rotor shaft 112. The clutch module 132 includes a shaft assembly comprising the motor shaft 130, a

SS coupling element 200 fixedly attached to the end 202 of the motor shaft 130 and an electrically insulating element 204 coupled between the motor shaft 130 and the coupling element 200. In this embodiment, the motor shaft 130 includes a flange 206 at the end 202 of the motor shaft. motor shaft 130. The flange 206 has a first side 208 and a second side 210 opposite the first side 208,

The electrically insulating element 204 is Legen, i.e. abuts the second side 210 of the flange 206. The electrically insulating element 204 may be a disk or annular element. The electrically insulating member 204 may be substantially the same diameter as the flange 206 and may be axially aligned with the motor shaft 1530. The electrically insulating member 204 may be formed of any appropriate electrically insulating material, including, but not limited to, a ceramic material, alumina, and/or zirconium oxide. The electrically insulating element 204 may be formed as a coating applied to one or both of the second side 210 of the flange 206 and/or the side of the coupling element 200 facing the flange 206. The coupling element 200 is against, i.e. contacts the electrically insulating element 204 which is located on the opposite side of the electrically insulating element 204 with respect to the flange 206.

Thus, in this embodiment, the electrically insulating member 204 is sandwiched between the coupling member 200 and the flange 206 of the motor shaft 130. The electrically insulating member 204 keeps the coupling member 200 and the motor shaft 130 spaced apart. The electrically insulating member 204 primarily provides electrical insulation between the motor shaft 130 and the coupling member 200. The thickness of the electrically insulating member 204 between the surface that abuts the flange 206 and the surface that the coupling members 200 lie on may depend on the application. Preferably, the thickness of the insulating element 204 is between about 1 mm and 5 mm. More preferably, the thickness of the insulating element 204 is between about 1.2 mm and 1.8 mm. Even more preferably, this thickness is approximately 1.5 mm. Such a thickness generally calculates that the insulating element 204 is robust enough to reduce the risk of damage during transportation, installation and use, while at the same time being relatively easy to manufacture. is. in this embodiment, the coupling element 200 is an annular or tubular collar. The coupling element 200 is fixedly attached to the flange 206 with a plurality of 253 fasteners 212. The fasteners 212 may be threaded fasteners. In this embodiment, the fasteners 212 are located in respective feed-through openings 214 through the flange 206, from the first side 208 of the flange 206 to the second side 210 of the flange 206. The fasteners 212 continue to extend through the electrically insulating element 204 and extend extends into the coupling element 200 whereby the motor shaft 130, the electrically insulating element 204 and the coupling element 200 are fixedly connected to each other. The fasteners 212 can be screwed into the coupling element 200 . The fastener heads 216 of the fasteners 212 are located on the first side 208 of the flange 206,

The mounting heads 216 are located in recesses or recesses 218 on the first side 208 of the flange 206. In this embodiment, the mounting means 212 are necessarily electrically isolated from the motor shaft 1530.

Specifically, in this embodiment, an electrically insulating washer 220 is located respectively between each of the mounting heads 216 and the flange 206, particularly between each of the mounting heads zi6 and the base of the respective recess 218 on the first side 208 of the flange 206. }. Also in this embodiment, the walls of the feed-through openings 214 are spaced from the desites of the fasteners 212 placed therein. For example, there are air gaps between the walls of the conduit openings 214 and the portions of the fasteners 212 passing therethrough. The electrically insulating washers 220 may be made of any suitable insulating material, including, but not Decerkt to, a ceramic material. , alumina and/or zirconium oxide.

In this embodiment, a further washer 222 is located respectively between each of the fastener heads 216 and the flange 206. The further washers 222 are sandwiched between the fastener heads 216 and the electrically insulating washer 220. Alternatively, the further washers 222

The fasteners 222 are between the flange 206 and the electrically insulating washers 220, so long as the electrical insulation between the fasteners 212 and the flange 205 is maintained. The washers 222 may be made of any suitable material, such as metal, for example steel.

Advantageously, the use of the additional retaining discs 222 distributes the loads applied to the electrically insulating retaining discs 220 more evenly. Thus, the likelihood of damage to or breakage of the electrically insulating washers 220, which in some embodiments can be quite brittle, is reduced or eliminated. In this embodiment, the coupling member 200 is an annular or tubular collar configured to wrap around the end of the rotor shaft 112 Le fit. The coupling element 200 encircles a central axis and defines an axial bore 224. The end 226 of the rotor shaft 112 is received in the axial bore 224. The surface of the axial bore 224 has a mating surface structure defined thereon (e.g., a ribbed surface or a surface with one or more protrusions or grooves) for engaging a compatible spacing structure defined on the surface of end 226 of rotor shaft 112. Due to the interlocking, compatible mating surfaces of the axial coring 224 of the coupling element 200 and the end 226 of the rotor shaft

112, lower circumferential movement of the coupling element 200 and the rotor shaft 112 is prevented or resisted, but relative axial movement may be possible if desired.

Thus, the coupling element 200 fixes the motor shaft 130 and the rotor shaft 112 together. Advantageously, this attachment is such that the motor shaft and the roccras are electrically isolated from each other. This electrical insulation of the rctor shafts and motor shaft may reduce or eliminate the passage of electrical current loops through the shafts. Consequently, the electrical currents through the bearings rotatably supporting the rotor shaft can be reduced or eliminated.

Advantageously, this can reduce damage to or wear of the bearings.

Advantageously, the electrically insulating coupling between the motor shaft and roller shaft described above is resistant to fatigue and breakage, for example due to corrosive and/or high temperature gases pumped through the vacuum pore.

Advantageously, the device described above is more compact than devices using a flexible coupling between the motor and the rotor shaft. The use of additional bearings is generally avoided. 23 In the above embodiments, the vacuum pump is an oil-lubricated rotary screw vacuum pump with variable speed drive {VSD}. The vacuum pcmp is a single trace pump.

However, in other embodiments, the vacuum pump is another type of device, such as a compressor or an expander, or another type of vacuum pump, such as a dry vacuum pump, a dilator pump, a Roots L-type vacuum pump, or a multi-stage vacuum pump. in the above embodiments the motor is an alternating current electric motor. In other embodiments, however, the MOTO is a different type of engine. in the above embodiments: the motor is controlled by a controller comprising a VFD (variable frequency drive). However, in other embodiments the motor is controlled in a different way. 18 In the above embodiments, the vacuum pump comprises cen = pair of ini interlocking Yotors. However, in other embodiments, the vacuum pump comprises a pumping mechanism with a different number of rotors.

In the above embodiments, the mounting heads are recessed into the first flange. In other embodiments, however, one or more of the mounting heads is not countersunk in the first flange,

In the above embodiments, the fasteners are substantially electrically isolated 23 from the motor shaft by respective electrically insulating corg discs and by spacing the walls of the feed-through openings from the portions of the fasteners that pass through.

In other rear embodiments, the mounting means are otherwise substantially electrically isolated from the motor shaft.

For example, in some embodiments, there is an annular electrically insulating member about the first axis that abuts the flange on the first side of the flange. The fasteners are arranged to pass through the annular electrically insulating member, through the flange, through the electrically insulating element, and enter the coupling element. The annular electrically insulating element is located

Loop the mounting heads and the first side of the & [lens, thereby positioning the mounting heads at a distance from the first side of the flange Le, The annular electrically insulating element can be considered to provide the same electrically insulating functionality as the electrically insulating washers in the above embodiments, and the individual electrolytic locking washers may be omitted.

Figure 3 is a schematic illustration showing such an embodiment of the link module 132 . Elements that this embodiment has in common with the embodiment of Figure 2 are designated with the same position numbers. in this embodiment, the mounting heads 215 are not recessed into the first link 206.

In this embodiment, the coupling module 132 comprises a further electrically insulating element 300. The further electrically insulating element 300 is positioned against, i.e. close to, the first side 208 of the flange 206. The further electrically insulating element 300 can be a disc or an annular element. The further electrically insulating member 300 may have substantially the same diameter as the flange 206 and may be axially aligned with the motor shaft 130. The further electrically insulating member 300 may be formed of any suitable electrically insulating material, including, but not limited to, a ceramic material, alumina and/or zirconium oxide.

The further electrically insulating element 300 can be designed as a coating on the first side 208 of flange 206.

B In some embodiments, the further electrically insulating element 300 is substantially the same as the electrically insulating element 204.

In this embodiment, the coupling module 132 comprises a disc 302. The disc is located Legen, i.e. abuts against the further electrically insulating element 300 so that the further electrically insulating element 300 is sandwiched between the [iens 206 and the further electrically insulating element 300. disc 302 is spaced apart from and electrically isolated from motor shaft 130.

The disc 302 may also be located between the flange 206 and the further electrically insulating element 300, so long as the electrical insulation between the mounting means 212 and the flange 206 is maintained.

The disc 302 may be formed of any suitable material, such as metal, e.g. steel,

Advantageously, the use of the disc 302 distributes the fur tendons exerted on the electrically insulating element 300, for example by the fasteners 212, more evenly. Thus, the likelihood of damage to or breakage of the further electrically disclosing element 300, which may be relatively brittle in some embodiments, is reduced or eliminated. The disc 302 can be considered to serve a similar purpose to the further retaining discs 222 of the previous embodiment. The fasteners 212 continue, securing the disc 302, the further electrically insulating member 300, the flange 206, the electrically insulating member 204 and the coupling member 200 together. The electrically insulating member 204 and the further electrically insulating member 300 substantially insulate the motor shaft 130 electrically separates from the coupling element 200. The thickness of the further electrically insulating element 300 between the surface abutting the flange 206 and the surface abutting the Kkoopeling element 302 may depend on the application.

Preferably, the thickness of the further insulating element 300 is between about 1 mm and 5 mm.

More preferably, the thickness of the further illustrative element 200 is between about 1.2 mm and 1.8 mm. Still more preferably, this thickness is about 1.5 mm.

Such a thickness means that the further insulating element 300 is robust enough to reduce the risk of damage during transport, installation and use, while at the same time being relatively easy to manufacture.

Optionally, further washers (e.g., metal washers) can be implemented to distribute loads on the otherwise electrically insulating element 300 and/cf the disc 302 Le, thereby reducing the likelihood of its damage. in which the fasteners are located, are coated with an electrically resistive or insulating material to prevent or prevent the passage of electrical current between the fasteners and the flange.

The electrically resistive or insulating material may coat the recessed or recessed portions of the flange in embodiments where they are provided.

In the above embodiment, the rotor shaft and the motor shaft are coupled to each other by an annular or ; 5 tubular coupling element attached to a [lens on the motor shaft, and mounted around the rotor shaft, receiving PHOTOs securely,

However, in other embodiments, the motor shaft and the rotor shaft are coupled together in some other way in which they are electrically isolated from each other. For example, in some embodiments, the rotor shaft includes a flange at its end. The annular or tubular coupling element is attached to the rotor shaft {Ílens in the same way as described above 18 for the motor shaft. The headstock element fits around the motor shaft and securely receives this motor shaft in the same way as described above for the rotor shaft.

By way of another example, in some embodiments, both the rotor shaft and motor shaft include respective flanges at their respective ends. The flanges of the rotor shaft and motor shaft may be coupled together such that they are electrically isolated from each other. For example, an electrically insulating 254 element between the two {lenses to keep the flanges spaced apart, Multiple fasteners can pass through both flanges and the electrically insulating element between them, The fasteners can be electrically isolated from one or both of the flanges, e.g. as described above for the motor flange. That is, the fasteners may be electrically insulated from one or both flanges by electrically insulating washers (fitted between fastener bodies and a flange, and/cf between fastener nuts and a flange) and air gaps between the fasteners and the walls of the conduit openings.

By way of another example, the flanges of the rotor shaft and motor shaft may be coupled together by one or more clamps which contact the flanges through electrically insulating material.

In the above embodiments, the mounting heads are located on the side of the rotor shaft flange opposite the coupling element. However, in other embodiments, the fastener heads are on the same side of the rotcras flange as the K-coupling member, and the fasteners enter and connect to the flange.

LIST POSITION NUMBERS

100 - vacuum pump unit 102 - Vaculim pump 104 - motor & 106 - housing 108 — pump chamber 110 - screw rotors 112 - rotor shafts 114 - gas inlet 19 116 - gas outlet 118 — suction port 120 — discharge port 122 — suction side bearing housing 124 — first bearings 126 — delivery side bearing housing 128 — second bearings 130 — motor shaft 132 — coupling module 200 — coupling element 29 202 — end of rotor shaft 204 — electrical isclosing element 206 — fiens 208 — first side 210 — second side 23 212 - fasteners 214 - conduit holes 216 - fastening heads 218 - recesses or recesses 229 - electrically insulating washers 222 - additional washer 224 - axial bore

226 = end of the rotor shaft 300 = further electrically insulating element 302 - disc

Claims (5)

CONCLUSIONS An axle assembly comprising: a first axle having a first axle end; a coupling member fixedly attached to the first shaft end & the coupling member configured to be fixedly attached to a second shaft end of a second shaft Le; and an electrically insulating member coupled between the first shaft and the coupling member to thereby electrically isolate the first shaft from the coupling member. The axle assembly of claim 1, further comprising the second axle with the second axle end, the coupling element being attached to the second axle end of the second axle. 3. The shaft assembly of any one of the preceding claims wherein the first shaft is a shaft selected from the group of shafts consisting of a rotor shaft of a vacuum pump, a compressor or an expander, and a motor shaft of a motor for driving of a roller shaft of a vacuum pump, a compressor or an expansion device. The axle assembly of any preceding claim, wherein the coupling member is an annular GE tubular collar configured to fit around the second axle end of the second axle Le. 25 5. The axle assembly of any one of the preceding claims, wherein the coupling element is fixed to the first axle end of the first axle with a couple of mounting means, the one or more mounting means being electrically isolated from one or both of the first axle and the coupling element. The axle assembly of any one of the preceding claims, wherein the first shaft has a flange oval located at the second shaft end, and the coupling element is attached to the [lens]. 7. The axle assembly of claim ©, further comprising one or more fasteners positioned through the flange from a first side of the flange to a second side of the flange Lec on the second side of the flange, wazrbi7 the one or more fasteners extend into the 19 Kcoupling element, which coupling element is on the second side of the flange, The axle assembly of claim 7, further comprising one or more electrically insulating elements located between the one or more mounting means and the flange to thereby electrically isolate the one or more mounting means from the first axle. 3, The shaft assembly of claim 8, wherein one or more further electrically insulating elements comprises an annular electrically insulating element rositioned about the first axis, the annular electrically insulating element being on the first side of the flange. 10. The axle assembly of claim 9, further comprising an annular metal disc seated against the annular electrically insulating element. 11. The axle assembly of claim 8, wherein: the one or more further electrically insulating elements comprise one or more electrically insulating washers, each electrically insulating washer being located between the first side of the flange and a portion of a respective one or more mounting members is located; and optically, the shaft assembly further comprises one or more metal washers, each metal washer contacting one or more electrically sensing washers, respectively, and being sandwiched between the first side of the flange and a head of one or more respectively. fasteners are located. 12. A vacuum pump, compressor, or expander comprising: a vacuum pump, a compressor, or an expander having a rotor on a rotor shaft rotatably mounted in a housing - a motor with a motor shaft; wherein the motor shaft is coupled between the rotor shaft and the motor: the motor is configured to rotate the motor shaft thereby driving the rotor shaft; and the motor shaft and rotor shaft are electrically isolated from each other. The module of claim 12, further comprising: a clutch member fixedly attached to an end of the motor shaft and an end of the rotor shaft, thereby fixedly fixing the motor shaft and the rotor shaft together; and 253 an electrically insulating element between either the motor shaft and the coupling element or the rotor shaft and the coupling element. 14. The module of claim 13, wherein the motor shaft includes a flange located at the end of the motor shaft: the module further comprises: one or more fasteners positioned by the flange from a first side of the flange to a second side of the flange opposite the first side of the flange, the one or more fasteners extending into the coupling member, which coupling element is on the second side of the flange : is located; and one or more further electrically insulating elements located between the one or more fasteners and the {lens; the electrically generating element is located between the motor shaft and the coupling element; and the coupling element is an annular or tubular saw in which the end of the rotor shaft is received, The module of any one of claims 12 to 14, wherein the vacuum pump is a lubricated rotary screw vacuum pump LE.