BE1027220B1 - A compressor and / or vacuum pump device, a liquid return system for such compressor and / or vacuum pump device and a method for discharging liquid from a gear box of such compressor and / or vacuum pump device - Google Patents

Abstract

A compressor and / or vacuum pump device with a liquid-injected compressor or vacuum pump element (2), which comprises a liquid return system (7), a motor (4) for driving the compressor or vacuum pump element (2), a gearbox (3) arranged between the motor (4) and the compressor and vacuum pump element (2), respectively, and a liquid separation vessel (5) in fluid communication with an outlet (6) of the compressor and vacuum pump element (2), respectively, the liquid return system (7) comprising a main body (8) comprising a chamber in which a first fluid flow (11) from the liquid separation vessel (5) and a second fluid flow (15) from the gearbox (3) are mixed together to form a third fluid flow (20), which third fluid flow (20) ) leaves the chamber via an outlet (16) and is sent to and into the liquid-injected compressor or vacuum pump element (2) via the injection point (17).

Description

| BE2019 / 5424

À A Compressor and / or vacuum pumping equipment, san vice return system for such compressor and / or | vacuum pump apparatus and a method for discharging liquid from a gearbox of such a Compressor and / or vacuum pumping device. The present invention relates to Dop een | compressor and / or vacuum pumping device with a fluid # 22 injected compressor and / or vacuum pumping element, respectively, a vinegar return system for such compressor and / or vacuum pumping device and a method for discharging 9 fluid from a gearbox of such compressor and / or vacuum pumping device.

More specifically, the present invention relates to a compressor and / or vacuum pump device having a liquid return system comprising a main body having multiple inputs and an output, one of the inputs 22 being in fluid communication with the gearbox. In the state of the art, compressor and / or vacuum pump devices are known with a liquid-injected compressor or vacuum pump element, in which the liquid-injected compressor or vacuum pump element is driven via a shaft, this shaft can be driven via a gearbox, which gearbox is in turn driven by means of a drive shaft driven by a motor.

The liquid that is injected, for example oil, is used for lubrication, cooling, sealing and / or corrosion protection of moving parts in the compressor or vacuum pump element. | In order to avoid leaks between the COMpPressor and / or 9 vacuum pump element on the one hand and the motor on the other hand, 9 on the one hand the compressor and / or vacuum pump element and the 9 gear wheel are liquid-tight: separated from each other by | 10 by means of a first seal on the shaft with which the compressor and vacuum pump element is driven, and 9 on the other hand, the motor and the gearbox are separated from each other in a liquid-tight manner by means of a second seal on | the drive shaft that drives the gearbox.

However, the seals mentioned above are susceptible to failure causing fluid to flow to and into the gearbox, especially on high speed variable speed drive motors. If the seals fail, fluid will accumulate in the gearbox, causing the COMDre @ ssor- and / or vacuum pumping equipment must be shut down for maintenance to remove this accumulated fish fluid from the gearbox, which can cause long downtimes. In addition, in components of the compressor and / or vacuum pumping equipment from which fluid has leaked to the gearbox, these fluid must be replenished during this maintenance, which further increases the downtime of the compressor and / or vacuum inverter. 9 In addition, in classic Compressor and / or | 5 vacuum pump devices the seals fail | directly visually detectable since the gearbox 9 traditionally comprises a closed and opaque housing 9, so that the need for maintenance cannot be determined on the basis of this type of direct visual detection. : The seals can only be inspected visually 9 by stopping the compressor and / or vacuum pump assembly and disassembling the compressor and / or vacuum pump assembly 9 to expose the seals | 15 for an observer.

Even when the compressor and / or vacuum pump assembly is disassembled and the seals exposed, it may be difficult to impossible to detect a possible failure of the seals during operation of the compressor and / or vacuum pump assembly, if this failure occurs, for example, only when the compressor and / or vacuum pump equipment is in operation.

Sensors are known for detecting leaks in a compressor and / or vacuum pump device which can be built into a housing of the compressor and / or vacuum pump device in an integrated manner. However, this type of sensors can be complex in structure, can be their internal integration into the compressor

, BE2019 / 5424 and / or vacuum pump assembly are difficult to replace and / c maintain, and fundamentally do not offer an option to prevent and / or even remedy the calming and failure of seals in the COMDressor and / or vacuum pump assembly, {5 | Here, the compressor and / or vacuum pumping equipment serves | Failure of the seals to be stopped to prevent the co-emission of vice dust in the gearbox 9 and / or remedy it. # 10 9 Systems to avoid and / or remedy this accumulation of fluid in the gearbox 9 Often consist of several 9 parts that are difficult to maintain and / or replace [when integrated into the compressor and / or compressor in an integrated manner or vacuum pumping device. The present invention has the object of providing a solution to one or more of the aforementioned and / or other disadvantages.

To this end, the invention relates to a co-processor and / or vacuum pump device with a liquid-injected compressor or vacuum pump element, which compressor or vacuum pump device, in addition, a liquid return system, a motor for driving the liquid-injected compressor or vacuum pump element, and a gearbox between the two. motor and the vice-injected COMpresgor and vacuum pump element, respectively, and a liquid separation vessel in fluid communication with a

N BE2019 / 5424 includes outlet of the vice-injected compressor or vacuum pump element,

wherein the liquid return system has a main body with | a room with an exit and a first entrance | 5 cm vessel, the first entrance being in fluid communication with the | fluid separation vessel and receiving a first fluid stream from the fluid separation vessel, and 9 wherein the outlet is in fluid communication with an injection point | 160 of the liquid-injected compressor and 9 vacuum pump elements, respectively, 9, characterized in that the chamber is further provided with sensors. second inlet that is in fluid communication with the gear box and receives a second fluid flow from the gear box, the chamber being configured to merge said first fluid flow and second fluid flow into a third fluid flow, said third fluid flow exiting the xamer via the outlet and is controlled to and into the liquid-injected compressor-respectively vacuum pump element via the injection point.

An advantage of the compressor and / or vacuum pump device according to the invention is that vice-substance which, upon failure of seals in the gearbox, acoumulsates, can be discharged to the second entrance of the chamber of the main body of the vinegar return system.

The discharged liquid may then form a mixture in the chamber with the incoming first fluid stream coming from the liquid separation vessel and entering the chamber through the first entrance, after which this mixture exits the exit.

G can be sent from the chamber to the injection point of the liquid-injected compressor and / or vacuum pump element, {5 In this way, the fluid that has leaked into the gearbox due to failure of the seals is not lost and this fluid is not lost. returned to the compressor and / or | vacuum pump element for its lubrication function, | cooling, sealing and / or corrosion protection of moving parts of the compressor and / or vacuum pump element 9, 9 in a preferred embodiment of the compressor and / or vacuum pump device according to the invention, the second entrance is by means of a suction line in fluid communication. with the Land gearbox, where the suction pipe is preferably made of a transparent material,

In such a transparent suction line, the presence of liquid, and consequently the failing of the seals in the compressor and / or vacuum pumping device and associated accumulation of vice in the tanowie cabinet, is easy to detect visually,

in a more preferred embodiment of the compressor and / or vacuum pumping device according to the invention, the suction line is provided with a sensor configured to detect the presence of liquid in the suction line,

With the aid of a sensor, the presence of liquid in the suction line can be evaluated and detected on the basis of a predefined criterion in a systematic and objective manner 9, ie a subjective evaluation of the presence of liquid in the | aspiration by a human observer can be avoided by using the sensor. {Preferably the sensor is an optical sensor, since # i0 this kind of sensor is simple and compact by Structure, | such that the sensor can easily be integrated into the suction line 9, and because an optical sensor is extremely suitable for detecting any presence of liquid in the suction line.

in an even more preferred embodiment of the compressor and / or vacuum pumping device according to the invention, the sensor is provided with a transmitter configured to send out a signal that can be received by a receiver. In this way, the presence of vice-substance in the suction pipe and the failure of the seals in the compressor ”and / or vacuum pump device underlying this, are co-wetted by the receiver in such a way that the receiver can be warned of a possible failure of the seals, preferentially the signal sent by the transmitter, a wireless signal is emitted, so that you have a long distance. Loops between the transmitter and the receiver in a long transmission line

| BE2019 / 5424 8 to send the signal between the transmitter and the receiver can be avoided.

In a further preferred embodiment of the compressor and / or vacuum pumping device according to the invention 9, the liquid return system further comprises an air blow valve integrated on the head body, {If a pressure in the main body of the | 10 liquid recovery system a predefined limit value | fluid can be vented through the vent # 9 By integrating the vent valve on the main body, these two parts of the liquid return system also form a continuous compact unit without an additional required intermediate pipe with connections along which fluid can leak.

As a result, the functionalities that these two components fulfill in the liquid return system are also located in a limited space, which can facilitate assembly, maintenance and / or recovery of components in the vice return system, in a further preferred embodiment of the compressor and / or vacuum pump device according to the invention. the liquid return system further includes a control unit integrated on the main body, which control unit 39 is configured to control a flow rate of the third fluid flow.

Since the exit of the chamber of the fluid return system hoc fdilicheam is configured to be in fluid communication with an injection point of the fluid-injected COMpIKESSOr or vacuum pump element, respectively, by means of the aforementioned | control unit the flow rate of the third fluid flow passing through | When the liquid return system is injected back into the compressor or vacuum pump element, respectively, these two components of the 9 vice return system form a compact whole. By integrating the control unit on the main body 9, these two components of the 9 vice return system form a compact unit. As a result, the functionalities that these two components fulfill in the liquid return system are located in a limited space, which can facilitate assembly, maintenance and / or repair of components in the liquid return system. In a further preferred embodiment of the compressor and / or vacuum pumping device according to the invention. The fish return system further comprises a vacuum generating means, the vacuum generating means generating a vacuum in the gearbox.

By "negative pressure" in this context is meant a pressure that is lower than the pressure of the fluid compressed by means of the compressor and / or vacuum inflator at the outlet of the COMCRESSor or vacuum pumping element, respectively.

With the housing of the vacuum generated by the vacuum generating agent in the gearbox, fluid that enters the gearbox as a result of seal failure can be sucked into the main body and into the core of the viscous return system, possibly in the opposite direction. driving forces 9 moving the fluid from the main body to the gearbox | could carry, An example of these counteracting [driving forces is, for example, gravity when | The main body of the vice return system is positioned at a higher level than the gearbox of the compressor and / or vacuum pump device. 9 Preferably, the vacuum generating means is provided in the main body of the liquid return system. preferentially as a venturi selector.

Integrating the suppressant in the main body of the liquid return system ensures that the fish return system can be constructed in a compact and modular manner.

Venturi ejectors are simple and compact in construction, as they do not include moving parts to create the negative pressure.

In a preferred embodiment of the compressor and / or vacuum pumping apparatus according to the invention, the first entrance to the chamber of the main body of the liquid return system is via a throttle in fluid communication with the liquid separation vessel.

By means of this throttle means, a flow rate of the highest fluid flow from the liquid separation vessel to the first entrance of the chamber of the main body of the liquid return system can be determined and / or controlled. | The invention also relates to a liquid return system for a COMDressor and / or vacuum pump device with no liquid injected COMPLESSOR or vacuum pump element, 9 10 which compressor and / or vacuum pump device furthermore a MOTOF for driving the liquid sieving device. compressor and vacuum pump element, respectively, a gearbox arranged between the motor and the liquid-injected compressor and vacuum pump element, respectively, and a liquid-containing liquid separation vessel in fluid communication with an outlet of the liquid-injected compressor and vacuum pump element, respectively, the liquid-liquid return system comprising a main body with a chamber includes an outlet and a first inlet, the first inlet being configured to be in fluid communication with the liquid separation vessel and receiving a first fluid flow, and the outlet being configured to be in fluid communication with an injection point of the liquid-injected compressor and vacuum pump element, respectively characterized in that the chamber further includes a second inlet configured to be in fluid communication with the gearbox and receive a second fluid flow, the chamber being configured to

== BE2019 / 5424

The first fluid stream and second fluid stream are intended to mix together to form a third fluid stream, which third fluid stream exits the chamber through the outlet, and that the virgin fluid return system continues on the way. S main body integrated control unit CHVEE, which is configured for a flow rate of the third | fluid flow, $ It is understood that such | 12 liquid return system offers the same advantages as the above described compressor and / or vacuum pump device according to the invention. In a preferred embodiment of the liquid return system according to the invention, the liquid return system is designed as a modular element in relation to the compressor and / or vacuum pump device, such that the liquid return system can be brought into fluid communication with the compressor and / or vacuum pump device in a detachable manner. and that the compressor and / or vacuum pump device can continue to function under normal operating conditions after disconnection from the vice return system.

By "normal operating conditions" in this context is meant that there is no failure of the seals of the compressor and / or vacuum pump equipment.

The advantage of designing the liquid return system in such a way as a modular element is that it can be connected, as it were, to the compressors and / or vacuum pumping device as a piecemeal element, whereby the liquid return system can be easily removed from the compressor and / or vacuum pumping device. can become 9 for maintenance and / or replacement, for example, without | 3 that for this purpose the compressor and / or vacuum pumping device | nocdzaxelijkerwiize should be shut down. Finally, the invention also relates to a method for discharging liquid from a gearbox of a | compressor and / or vacuum pump device with a liquid-injected compressor and vacuum pump element, respectively, the compressor and vacuum pump device, respectively, further comprising a motor for driving the liquid-injected compressor and vacuum pump element, respectively, and a liquid separation vessel in fluid communication with an outlet of the liquid injected compressor or vacuum pump element, where the gearbox is arranged between the motor and the liquid-injected compressor or vacuum pump element, respectively, characterized in that the liquid is removed from the gearbox by means of a vice-substance return system via an fluid connection between this vice-substance return system and the gearbox and mixed with a flow of fluid from the liquid separation vessel, after which the viscous substance is mixed with this fluid flow to and into the liquid-injected compressor or v acuimponpelement: is controlled.

It goes without saying that such a method for discharging vice dust from a gearbox of a compressor and / or vacuum pump device with a liquid-injected compressor or vacuum pump element offers advantages analogous to the advantages of the compressor and / or vacuum pump device described above and 9 > liquid return system according to the invention. | With the intentions to improve the features of the invention, Le 9 Wages are given below, by way of example, without any limitation character, a preferred embodiment of the compressor and / or vacuum pump device according to the invention | and the liquid return system for such a compressor and / or vacuum pump device, described with reference to the drawings, in which: figure 1 shows a compressor and / or vacuum pump device with a liquid-injected compressor or vacuum pump element according to the invention; fiquur 2 shows an isometric view of a vice-substance recovery system according to the invention,

Figure 1 A compressor and / or vacuum pump device 1 according to the invention with a liquid-injected compressor or vacuum pump element 2 is useful. The compressor or vacuum pump element 2 is driven via a transmission in a gearbox 3 by means of a motor 4. The compressor. and vacuum pump device 1 further comprises a liquid separation vessel 5 which is in fluid communication with a SE2019 / 5424 outlet 6 of the liquid-injected compressor and vacuum pump element 2. Further, the compressor and / or vacuum pumping device 1 comprises a vice-substance return system 7 comprising a main body. 8. The first inlet 9 of the main body 8 of the liquid return system 7 is in fluid communication with the liquid separation vessel 5, preferably via a throttle means 10, and receives a first fluid flow 11 from this liquid separation vessel 5. By means of the throttle 10 can have a flow rate of ee The first fluid flow 11 of the liquid separation vessel 5 but the main body 15 can be controlled, the second inlet 12 of the main body 8 of the liquid return system 7 is further also in fluid communication with the gearbox 3 via a suction line 13, preferentially through a check valve 14, such that a second fluid flow 15 through the suction line 13 can only run from the gearbox 3 to the fluid return system 7.

254 Furthermore, an outlet 16 of the main body of the liquid return system 7 is in fluid communication with an injection point 17 of the compressor and vacuum pumping element 2, respectively.

38 This injection point 17 is typically located in the inlet valve 18 of the compressor or vacuum pump element 2, respectively.

The main body 8 includes a vacuum generating means 19 configured to generate a vacuum in the gear box 3 whereby the second fluid stream 15 is drawn in from the gear box 3. In the main body & the first fluid flow 11 and the | second fluid stream 15 mixed to a third fluid stream | 20 which is sent via the outlet 16 to the injection point 17 of the compressor "respectively vacuum pump element 2 | LG.: In this way, liquid entering the gearbox 9 through failing seals in the COMDressor 9 and / or vacuum pump device 1, is extracted from the gearbox 3 | 15 and recovered to the compressor or vacuum pump element 2 respectively. The suction line 13 is provided with a sensor 21, preferably an optical sensor, which is configured to detect the presence of liquid in the suction line 13 and consequent failure of the seals. To be detected, the sensor Zi is equipped with a transmitter 22 which is configured to send out a wireless signal that can be received by an external receiver.

This external receiver can for instance be a computer or smartphone with which operational conditions of the compressor and / or vacuum compressor 1 can be monitored and / or controlled remotely.

Lu BE2019 / 5424 17 In addition to a sensor 21 for detecting the presence of viscous dust in the suction line 13, it is of course not; excludes that the suction line 13 can further provide | of additional sensors, for example to reduce the degradation of up to 3 liquid that may be present in the suction pipe 13 | which may give a possible indication of the need to replace and / or regenerate this fluid in the Compressor and / or vacuum pump installation 1, # 10 Figure 2 shows the main body 8 of the 9 vice return system 7 according to the invention in more detail. detail, The main body & comprises a chamber provided with the outlet in L6 for the third fluid flow 20, the first inlet 9 for the first fluid flow 11 and the second inlet 12 for the second fluid flow 15, More specifically, the first inlet 3 is configured to To be in fluid communication with the pharmaceutical separation vessel 5 and receive the first fluid flow 11, the second input 12 to be in fluid communication with the gearbox 3 and receive the second fluid flow 15, and the output 15 to be in fluid communication with an injection point 17 of the liquid liquid injected compressor or vacuum pump element 2 and to direct the third fluid flow 20 out of the chamber, the main body & can provided with an additional outlet 23, which additional outlet 23 can be in fluid communication with the compressor and / or vacuum pump element 2 at a position downstream of the inlet valve 18; The main body & can further be provided with one or more boreholes Z4â, which ensure that the main body 8 is attached to a part of the compressor and / or | vacuum pump device 1 can be fixed, for example 9 by means of a bolt connection. | A relief valve 25 may be integrated on the main body 8. When a pressure of the first fluid flow 11 from the liquid separating vessel 5 exceeds a predefined limit value, this first fluid flow 11, possibly mixed with the second fluid flow 15 from the gearbox 2, can be vented via the venting valve 25.

Furthermore, a control unit 26 may be integrated on the main body 8. By means of this control unit 26, a flow rate of the third eluid flow 20 which is fed via the outlet 16 to the injection point 17 of the mineral-injected compressor or vacuum pump element 2, respectively, can be regulated.

The invention is by no means limited to the embodiments described by way of example and shown in the figures, but a COMDFE® S50I and / or vacuum pump and vice return system for such a compressor and / or vacuum pump can be realized in a variety of shapes, dimensions and variants. without the outside

LA BE2019 / 5424 scope of the invention as defined in the claims.

Claims (1)

Conclusions. 9 1.- A compressor and / or vacuum pump device with a | 5 liquid-injected CO compressor or 9 vacuum pump element {2}, 9 which compressor or vacuum pump device {1} | furthermore a fluid return system (73, a motor (4} for driving the fluid-injected compressor- 9 10 respectively vacuum pump element (2), a gearbox (3): arranged between the motor (43 and the vitamin-injected [COMpLESSOL- respectively vacuum pump element (2), and a visco-dust separation vessel (5) in fluid communication with an outlet (6) of the vice-injected compressor and vacuum pump element {2} respectively, wherein the vice-substance return system (7) comprises a main body {8} with a chamber provided with comprises an outlet {16} and a first inlet {9}, Where the first inlet (9) is in fluid communication with the liquid separation vessel (5) and receives a first fluid flow {11} from the vinegar separation vessel (5), and wherein the outlet ( 16) is in fluid communication with an injection point (173) of the liquid-injected compressor or vacuum pump element (2), characterized in that the chamber is further provided with a second inlet {12} which is in fluid communication with the gearbox {3) and receives a second fluid flow (15) from the gearbox (3), the chamber being configured to have the aforementioned version fluid flow (11) and second fluid flow (15) with to mix each other into a third fluid stream {20}, which third fluid stream {20} leaves the chamber via the outlet (16) and via the injection point {17} to and into the liquid injected compressor and vacuum pack element | {2} is sent. 2. The compressor and / or vacuum pump device according to claim 9, characterized in that the second inlet {12} is 9 by means of a suction line (13) in noisy connection 9 with the gearbox {3}. | 10 3.7 The compressor and / or vacuum pump device according to claim 2, characterized in that the suction line (13) is made of a transparent material, the compressor and / or vacuum pump device according to claim 2 or 3, characterized in that that the suction line (13) is provided with a sensor {21} configured to detect the presence of liquid in the suction line (13), The compressor and / or vacuum pump device according to claim 4, characterized in that the sensor {21} is an optical sensor, The compressor and / or vacuum pump device according to claim d or 5, characterized in that the sensor {21} is provided with a transmitter (22) which is configured to send a signal that can be co-captured by a receiver, 7. The compressor and / or vacuum pump device according to claim 6, characterized in that the signal is a wire locomotive signal. The compressor and / or vacuum pump device according to any one of the preceding claims 1 to 7, characterized in that | that the liquid-injected compressor and | vacuum pump element (2) a colie-injected compressor {respectively vacuum pump element, preferably an oil | 10 injected screw compressors resp. Leveli-k | screw vacuum pump element. The compressor and / or vacuum pump device according to any one of the preceding claims 1 to 7, characterized in that: 9 13 the liquid-injected compressor or vacuum pump element {2}, respectively, is a Waller-injected compressor or vacuum pump element, preferably a water-injected screw compressor or screw vacuum pump element. is, The compressor and / or vacuum pumping device according to any one of the preceding claims 1 to 5, characterized in that the vice-substance return system (7) further comprises an afolase hopper {25} integrated on the main body (8), il. The compressor and / or vacuum pump device according to any one of the preceding claims 1 to 10, characterized in that the liquid return system (7) further comprises a control unit (26) integrated on the main body {B}, which control unit {26} is configured to provide a flow rate. of the third fluid flow (20). And BE2019 / 5424 12. The compressor and / or vacuum pump device according to any one of the preceding claims 1 to 11, characterized in: that the liquid return system {73 furthermore transmits: a vacuum generating means {193 cva, which | The vacuum generating agent {19} generates a vacuum in the [gearbox {3}. 13. The compressor and / or vacuum pump device according to claim 12, characterized in that the # 10 underpressure generating means (19) is provided in the main body {81 of the liquid return system {7}, 9 preferentially as a venturi ejector. id. The compressor and / or vacuum pump device according to any one of the preceding claims 1 to 13, characterized in that the first inlet 19} is in fluid communication with the liquid separation vessel (5) via a throttle {10}. is. The compressor and / or vacuum pump device according to any one of the preceding claims 1 to 14, characterized in that the second inlet (12) is in fluid communication with the gearbox {3} via a non-return valve {14}, which non-return valve {14} is only a fluid flow of the gearbox {3} but the liquid return system (7) allows. 16.- A liquid return system for a concressor and / or vacuum pump device with a vice-injected compressor or vacuum pump element, which compressor and / or vacuum pump device (1}, furthermore, a motor {4} for driving the liquid injected compressor or vacuum pump element {2}, and a gearbox (3 arranged between the motor (4) and the liquid-injected compressor or 9 vacuum pump element (2), and a viscous separator vessel (5) {5 in fluid communication with an outlet {6} of the vice | injected compressor or vacuum heating element 9 (2) includes, | wherein the fluid return system (73 is a main body 9 {8} with a chamber provided with an exit (16) and a first 9 10 input {3} includes, : wherein the first input (9) is configured to be in fluid communication with the fluid separation vessel (5} and receive a first fluid flow (11), and wherein the output (16) is configured to be in fluid communication with an injection point {17} of be the vice-injected compressor or vacuum pump element {2} respectively, characterized in that the chamber is further provided with a second inlet (12) configured to be in fluid communication with the gearbox: (33 and a second fluid flow (15) wherein the chamber is configured to mix the aforementioned first fluid flow (11) and second fluid flow (15) together to form a third fluid flow m {20}, which third fluid flow (20) exits the core through the outlet {16}, and that the fluid return system {7} further on the main body (8: includes integrated control unit (263, which control unit (26)) is configured to provide a flow rate of the third control fluid flow (20), The liquid return system according to claim 16, characterized in that it further comprises a relief valve (25) integrated on the main body 9 (3). | 5 iS. ” The liquid return system according to claim 16 or | 17, characterized in that it further sen | suppressor generating agent (19) cravat, preferentially in the | main body (8: positioned, which underpressure generating means (19) is configured to generate a negative pressure in the gearbox (3), 9 ij. The liquid return system according to claim 18, characterized in that the underpressure generating means (19) is a venturi ejector. 20. The liquid return system according to claim 19, characterized in that it is designed as a modular element with respect to the compressor and / or vacuum pump device {1}, such that the liquid return system {71 is in fluid communication with the compressor and / or compressor. vacuum pump device {1} can be brought and that the Compressor and / or vacuum pump device (li after disconnection of the liquid return system {7} can continue to function under normal operational conditions. A method for removing liquid from a gearbox {3} or a COMpPrEessor and / or vacuum pump device (1) with a liquid-injected compressor or vacuum pump element {2}, wherein the compressor or vacuum pump device (1) furthermore motor (4) for driving the liquid-injected compressor or vacuum pump element (2 °) and comprises a liquid-separating vessel {5} in [fluid communication with a discharge {9} of the liquid-injected compressor or vacuum pump element | 5 {2}, | wherein the gearbox {3} is arranged between the motor 14} and the fluid-injected compressor or vacuum pump element (2), 9 characterized in that the fluid is disposed of by means of a fluid return system 9 (73 vis and fluid communication between this 9). liquid return system (7) and the gearbox (3} is removed from the gearbox (3) and with a fluid flow coming from the v ice dust separation vessel {5} is mixed, after which the liquid mixed with this fluid stream is sent to and into the liquid-injected COMpressor or vacuum pump element (2), respectively. The method according to claim 21, characterized in that an underpressure is generated in the gearbox 13) by means of an underpressure-generating means 119, The method according to claim 21 or 22, characterized in that the presence of liquid in the fluid communication between the liquid return system {7} and the gearbox {3} can be detected by means of a sensor {21}. The method according to claim 23, characterized. that the presence of liquid in the fluid communication between the liquid return system (7: and the gearbox | {3) is detected by an optical sensor. | The method according to claim 23 or 24, characterized in that the sensor (21) transmits a signal 9 via a transmitter {22} with information about the said presence of liquid {in the fluid communication between the liquid return system 9 {7} and the gearbox (3), which signal can be received by a receiver. The method according to claim 25, characterized in that the signal is a wireless signal.