EP2052158A1

EP2052158A1 - Rotor cooling for dry-running twin-shaft vacuum pumps or compressors

Info

Publication number: EP2052158A1
Application number: EP07786670A
Authority: EP
Inventors: Uwe Friedrichsen
Original assignee: Busch Produktions GmbH
Current assignee: Busch Produktions GmbH
Priority date: 2006-08-17
Filing date: 2007-08-13
Publication date: 2009-04-29
Also published as: DE102006038419A1; WO2008019815A1

Abstract

In a dry-running twin-shaft vacuum pump or compressor having two parallel shafts and positive-displacement rotors (2, 3; 17, 18; 23, 24) which are arranged on said shafts and which are located in a working space and which are synchronized in the ratio 1:1, for example mechanically by means of a transmission or electronically by means of one drive motor per rotor shaft, and which have an intake opening (1) on their suction side and at least one outlet opening (16) on their pressure side, the arrangement is configured such that each shaft (4, 5) of the positive-displacement rotors has an axially running cavity which extends at least over a partial length of the shaft, in which cavity in each case at least one heat tube (8, 9) is arranged in such a way that the compression heat from the positive-displacement rotors is dissipated out of the working space via the shafts, and is if appropriate conducted to an adjoining sealing space, and outside the working space, is dissipated out of the machine by heat dissipation means.

Description

Rotor cooling for dry-running twin-shaft vacuum pumps or

-Compressor

The invention relates to a dry-running twin-shaft vacuum pump or - compressor according to the preamble of claim 1.

Such a machine may be provided in a standing or lying version, and it may be the Verdrängerrotoren klauenkolbenförmig, helical, helical-spindle or waltz-shaped.

Increasing operating and disposal costs, increasing requirements for the purity of the pumped medium, and not least the new technical capabilities and the robustness of dry-running vacuum pumps and compressors have caused a great increase in applications in various fields in recent years.

Conventional oil circulation lubricated rotary vane vacuum pumps and compressors or liquid ring vacuum pumps and compressors work with liquid equipment. In these so-called. Single-shaft machines, the equipment is used to seal the working chambers and to remove the heat of compression. Such machines therefore have no special requirements for the cooling. In contrast, both dry-running vacuum pumps and compressors have the problem of dissipating the resulting heat of compression and thus ensuring adequate cooling. In vacuum pumps, which reach a final pressure in coarse and fine vacuum, the outlet temperature of the pumped medium increases with decreasing suction pressure. At the same time, the pumping medium can perform the compression work done with sinking flow only to a decreasing extent from the working space to the environment. The situation is similar with compressors. Here, too, the temperature increases in the working space with increasing differential pressure between suction and pressure side.

It is also known (EP 0 290 663 B1 or DE 198 20 523 A1), the heat of compression arising in such machines - instead of a conventional liquid cooling or smaller power instead of air cooling of the working space or the gear housing enclosing housing - by a direct Derive cooling of the rotor from the working space. In both known methods, the resulting heat of compression by means of coolant, preferably gear oil, is removed from the hollow-drilled rotor shaft by means of direct coolant injection and coolant return through an axis-center shaft bore.

However, both known solutions require on each of the two rotors a free shaft end for injecting the coolant. As a result, rising production costs are disadvantageously caused due to the additionally required intermediate drive shaft.

The invention is therefore based on the object, the dry-running twin-shaft vacuum pump or compressor of the generic type to eliminate the disadvantages described in such a way that the dissipation of the heat of compression from the working space is significantly improved by a simple, robust and cost-effective technical solution , The invention relates here to both flying and both sides of the working space mounted dry-running claw, screw and Wälzkolben- vacuum pumps or compressors, in which the two positive displacement rotors in the ratio 1: 1, for example, mechanically synchronized by means of an oil-lubricated gear transmission ,

The features of the invention to solve this problem emerge from claim 1. Advantageous embodiments thereof are described in the further claims.

The invention is based on the essential, astonishingly simple idea to make the design such that each shaft of the positive displacement rotors has an axially extending cavity extending at least over a partial length of the shaft, in which at least one heat pipe is arranged in each case such that the Condensation heat from the positive displacement rotors via the waves from the working space and possibly an adjacent sealing space and derived outside of the working space by heat dissipation means is derived from the machine.

The technology of the heat pipes themselves, also called "heat pipes", is well known. A heat pipe is an externally closed one

System that is hollow inside and in which there is a working equipment, which at the

Heat source evaporates, the heat with the steam centrally in the interior of the

Heat pipe transported to the heat sink and condensed there again. Of the

Reflux of the condensed working fluid to the heat source takes place at the outer diameter of the cavity by capillary forces. The technical design of the capillary structure on the inner wall depends on the design of the

Heat pipe off. As a working medium can be used in the temperature range used here

Water can be used. The required pressure in the heat pipe results from the desired operating points of the heat pipe. The transportable amount of heat can be up to a factor of 10,000 higher than solid copper. It is within the scope of the invention that as the heat dissipation means outside the working space cooled coolant, preferably gear oil, is used, which is supplied continuously by a coolant circuit.

According to the invention, the heat-dissipating means can also consist of metallic Wärmeableitkörpern particularly high thermal conductivity, which are attached to or near the respective heat sink at the end of the heat pipes at the shaft ends of the Verdrängerrotoren.

Advantageously, the metallic Wärmeableitkörper may consist of axial sleeves, which are arranged on the shaft ends of the Verdrängerrotoren; instead or additionally, it is also possible that the heat dissipation body consist of metal pins which radially pass through the shaft ends of the positive displacement rotors at or near the respective heat sink at the end of the heat pipes.

In a further embodiment of the invention, it can be provided that the positive displacement rotors are at least two-fold to increase the delivery volume and / or at least two stages to increase the total pressure difference and that the discharge of the compression heat from at least one heat source and at least one heat sink of a heat pipe per rotor.

According to the invention, the heat dissipation from the region of the heat sinks of the heat pipes or from the region of the heat dissipation body on the waves of the positive displacement rotors can take place with a precisely aligned, metered oil jet.

Conveniently, in the coolant circuit, an oil-air heat exchanger or an oil-water heat exchanger, in both cases, if necessary, an oil filter, be installed.

Preferably, for conveying the coolant, in particular oil, a coolant pump from the group of viscosity, centrifugal, threaded, gear,

CaitαnLalalror4_ nHor Ctβi irnhmi imno wαnm / aroHαt UJiαrHαi ict oo \ rm \ r + oil if Hio Coolant pump is attached to a free shaft end in the machine. Instead, it is also possible according to the invention to arrange the coolant pump outside the machine and to couple it via an intermediate magnetic coupling with a rotor shaft.

It is advantageous if the capillary structures used in the heat pipes are mechanically secured, in particular by positive engagement, soldering, welding, pressing, gluing or the like., Against rotation between the heat pipe and capillary structure.

It is also advantageous if the built-in rotor shafts heat pipes mechanically, in particular by positive engagement, soldering, welding, pressing, gluing or the like., Are secured against rotation between the heat pipe and capillary structure.

It is finally within the scope of the invention that, to improve the heat flow around the heat pipes around, and possibly also around the Wärmeableitkörper around, a heat conducting means is arranged, which prevented by a static elastic seals, such as O-rings or the like., From flowing is.

The invention will be explained in more detail below with reference to the drawing in the form of several embodiments. Hereby shows:

Figure 1 shows schematically in section the rotor cooling according to the invention on a cantilevered claw vacuum pump.

2 shows the rotor cooling according to the invention in a claw compressor mounted on both sides of the working space;

3 shows the rotor cooling according to the invention in a screw vacuum pump mounted on both sides of the working space; and Fig. 4 at a both sides of the working space mounted Roots pump.

In the cantilevered vacuum pump shown in Fig. 1, the heat of compression with two heat pipes, centrally incorporated in each rotor shaft of the compression bodies, here claw pistons, via the rotor shafts in the gear compartment and from there by means of heat exchangers or directly through the wall of the transmission housing in the outside environment.

The pumped liquid is sucked in via a dashed line indicated suction nozzle 1 from above and compressed against a control opening, not shown in the drawing below. The resulting heat of compression heats the housing around the claw pistons 2, 3 around and the claw pistons 2, 3 itself. The shafts 4, 5 are synchronized by two gears 6, 7. These synchronization gears 6, 7 and the bearing of the shafts 4, 5 are located in a gear housing and are oil lubricated. In the shafts 4, 5 respectively axially extending cavities are provided, in which heat pipes 8, 9 are arranged. These serve to drain the comparatively high proportion of heat energy to the gear compartment. At the end of the heat pipes 8, 9 in the gear compartment, the heat flow is transported radially to the heat through sleeves 4, 5 passing through the metal pins 10, 11 particularly high thermal conductivity (δ> 100 W / (K * m)) to Wärmeabithülsen 12, 13, extending axially the ends of the shafts 4, 5 are attached. The heat-releasing sleeves 12, 13 themselves are kept at a low temperature with cooled transmission oil exiting from aligned nozzles 31. For this purpose, an external cooler 32 is provided in order to keep the oil temperature in the transmission low and at the same time to achieve a high temperature difference across the heat pipes 8, 9.

In the claw compressor mounted on both sides of the working space shown in Fig. 2, the heat of compression is also with two heat pipes from the compression bodies, here claw pistons, on the rotor shafts in the side space against the gear compartment and from there by means of heat exchangers or directly on the wall of the transmission housing äußere dis outer Urgsgsb'jr.g abgegsbsn. The pumped liquid is sucked in via the dashed lines indicated suction nozzle 1 from above and compressed against a not visible in the drawing below control port. The resulting heat of compression heats the housing around the claw pistons 2, 3 around and the claw pistons 2, 3 itself. The shafts 4, 5 are synchronized by two gears 6, 7. Front side to the working space, opposite the synchronization gear 6, 7 is a second bearing 14, 15 of the shafts 4, 5. The heat of compression is in this embodiment with lubricated oil storage on a heat sink, consisting of good thermal conductivity radially arranged metal pins 10, 11 and axially extending Wärmeausithülsen 12, 13, at the end of the heat pipes 8, 9 derived in the bearing side space. From here then the heat can be dissipated either by direct air cooling or more effectively by the cooling circuit with cooler 32 from the machine.

In this bearing arrangement for dry-running claw, screw and Roots vacuum pumps and compressors and two heat pipes per shaft can be realized. These then have per displacement rotor or each wave a common heat source in the working space and their heat sinks each on one of the opposite end faces of the working space. The dissipative amount of heat can thus be further increased. 4 shows an arrangement with four heat pipes.

In the illustrated on Fig. 3 on both sides of the working space screw vacuum pump, the heat of compression is also delivered with two heat pipes from the compression bodies, here screw rotors, through the shaft ends in the gear compartment and from there by means of heat exchangers or directly through the wall of the transmission housing to the outside environment.

The fluid is sucked in via the suction port 1 from the side and compressed in the threads of the screw rotors 17, 18. An outlet nozzle 16 for the pumped medium is located at the other end of the helical spindle-shaped

Verdängerrotorβπ 17, 18. The resulting VerdichU-P.gsv.'ärrrie heats the Housing 19 around the screw rotors 17, 18 and the screw rotors 17, 18 itself. The screw rotors 17, 18 are synchronized by two gears 6, 7. Similar to the examples described here is the heat of compression at the free end of the shaft by an axially disposed Wärmeableitelement 22 and the shaft end of the driven screw rotor 17 with a heat dissipating sleeve 12 derived from the heat pipes 8, 9. From here, the heat is then dissipated either by direct air cooling or more effectively by the illustrated cooling circuit with cooler 32 from the machine.

In the case of the Roots pump mounted on both sides of the working space, shown in FIG. 4, the heat of compression is conducted with four heat pipes from the Roots pistons via their shaft ends into the two side spaces of the working space. From there, the heat of compression is released into the external environment with a common cooling circuit.

The pumped liquid is sucked in via the suction nozzle 1 indicated by dashed lines from above and conveyed downwards, not visible in the drawing, to the outlet 16. The resulting heat of compression heats the housing around the Wälzkolben 23, 24 and the Wälzkolben 23, 24 itself. The shaft ends of the Wälzkolbens 23, 24 are synchronized by two gears 6, 7. At the end of the working space opposite the synchronization gear 6, 7 there is a second bearing 25, 26 of the Wälzkolben 23, 24. The total of four heat pipes 8, 9, 27, 28 are in turn arranged centrally in the rotor central axes. The heat source of all four heat pipes 8, 9, 27, 28 is located centrally in the working space. In the two side chambers of the Roots pump, two of the four heat sinks are realized in each case. Here, the heat of compression at the shaft ends via a Wärmeableithülse 12 and three end-side heat sink 22, 29, 30 derived to the lubricating and / or transmission oil. From this then the heat of compression is derived by a simple cooling circuit with cooler 32 from the machine. With regard to features of the invention which are not explained in detail above, reference is expressly made to the drawings and to the claims, moreover.

Claims

claims

1. Dry-running twin-shaft vacuum pump or compressor with two parallel shafts and arranged thereon, located in a working space Verdrängerrotoren (2, 3, 17, 18, 23, 24), in the ratio 1: 1, for example mechanically by means of a transmission or electronically by means of a drive motor per rotor shaft, are synchronized and on its suction side a suction port (1) and at its pressure side at least one outlet opening (16), characterized in that each shaft (4, 5) of the positive displacement rotors an axially extending, at least has over a partial length of the shaft extending cavity, in each of which at least one heat pipe (8, 9) is arranged such that the heat of compression of the Verdrängerrotoren on the waves from the

Workspace and possibly an adjacent seal chamber forwarded and discharged outside of the work space by heat dissipation from the machine.

2. Vacuum pump or compressor according to claim 1, characterized in that as the heat dissipation means outside the working space cooled coolant, preferably transmission oil, is used, which is supplied continuously by a coolant circuit.

3. Vacuum pump or compressor according to claim 1 or 2, characterized in that the heat dissipation means of metallic Wärmeableitkörpern (10, 11) of high thermal conductivity of beisp. δ> 100 W / (K * m)), which are attached at or near the respective heat sink at the end of the heat pipes (8, 9) to the shaft ends of the positive displacement rotors.

4. Vacuum pump or compressor according to claim 3, characterized in that the metallic Wärmeableitkörper of axial sleeves (12, 13), which are arranged on the shaft ends of the positive displacement rotors.

5. Vacuum pump or compressor according to one of the preceding claims, characterized in that the Wärmeableitkörper of metal pins (10, 11) which radially pass through the shaft ends of the positive displacement rotors at or near the respective heat sink at the end of the heat pipes (8, 9).

6. Vacuum pump or compressor according to one of the preceding claims, characterized in that the positive displacement rotors to increase the delivery volume at least two columns and / or at least two stages to increase the total pressure difference and that the derivative of the compression heat from at least one heat source and at least one heat sink Heat pipe (8, 9) per rotor takes place.

7. Vacuum pump or compressor according to one of the preceding claims, characterized in that the heat dissipation from the region of the heat sinks of the heat pipes (8, 9) or from the field of

Heat dissipation body (10, 11, 12, 13) on the waves of the positive displacement rotors with a precisely aligned metered oil jet (31).

8. Vacuum pump or compressor according to one of the preceding claims, characterized in that in the coolant circuit, an oil-air heat exchanger, possibly also an oil filter, is installed.

9. Vacuum pump or compressor according to one of claims 1 to 7, characterized in that in the coolant circuit, an oil-water heat exchanger, possibly also an oil filter, is installed.

10. Vacuum pump or compressor according to one of the preceding claims, characterized in that for conveying the coolant, preferably oil, a coolant pump from the group of viscosity, centrifugal, threaded, gear, Seitenkanalrad- or pitot tube pumps is used.

11. Vacuum pump or compressor according to claim 10, characterized in that the coolant pump is attached to a free shaft end in the machine

12. Vacuum pump or compressor according to claim 10, characterized in that the coolant pump is arranged outside the machine and coupled via an intermediate magnetic coupling with a rotor shaft.

13. Vacuum pump or compressor according to one of the preceding claims, characterized in that in the heat pipes (8, 9) used

Capillary structures mechanically, in particular by positive locking, soldering,

Welding, pressing, gluing or the like, against twisting between

Heat pipe and capillary structure are secured.

14. Vacuum pump or compressor according to one of the preceding claims, characterized in that the built-in rotor shafts heat pipes (8, 9) mechanically, in particular by positive engagement, soldering, welding, pressing, gluing or the like., Against rotation between the heat pipe and capillary structure are secured.

15. Vacuum pump or compressor according to one of the preceding claims, characterized in that to improve the heat flow around the heat pipes (8, 9) around, and possibly also around the Wärmeableitkörper around, a heat conducting means is arranged that by static elastic seals, as O-rings or the like., Is prevented from draining.