DE1728100A1 - Hermetically or semi-hermetically encapsulated motor compressor - Google Patents

Description

"Hermetically or semi-hermetically encapsulated motor compressors, The The invention relates to a hermetically or semi-hermetically encapsulated motor compressor for liquid-lubricant-free, especially oil-free, compression of dry or moist gases. Damping, with the compressor as a reciprocating compressor one or more cylinders is formed.

There are piston compressors for "dry running" for compressing gaseous Media known in which the oscillating which is used directly for compression Components, in particular the piston, seal it against the cylinder wall Labyrinth arrangements or using self-lubricating plastic-based sealing rings or electrographized charcoal, # are designed for dry running, while the engine is always conventionally oil-lubricated.

The one used to seal the reciprocating piston rods and the to Drive shaft leading out of the crankcase requires sealing elements and, packing boxes on such machines are difficult to control and special in the case of oscillating movement, of course, not absolutely tight, for example special ones Measures to collect and return the leakage gas are required. Gaa losses of the conveyed medium are therefore generally unavoidable. the end the There is a need to seal the moving parts that are guided to the outside furthermore, in addition to the increased structural effort required for this, inevitably also an increased risk of operation due to the unavoidable susceptibility to failure the components used for this purpose, only with additional, increased maintenance effort Can Be Countered * A well-known way of solving the problem of oil control on the piston rods of such machines is, for example, that the distance between Guide bearing and stuffing box is chosen so large that that of a molecular The oil film did not wet part of the rod in the cylinder chamber during the upward gear got. However, this requires a considerable increase in the dimensions of such Compressors are accepted # which is undesirable in many cases. ' Known are on the other hand also hermetic or semi-hermetic reciprocating compressors with a or several cylinders in single and multi-stage design. One advantage of this Compressors is the elimination of the mechanical seal (shaft stuffing box) and the effective sealing of such machines from the outside achieved in this way. Gas losses, do not occur even after long periods of standstill.

The disadvantage here is that such machines are only lubricated with oil The engine and piston are designed and therefore not designed for dry running in this form can be used because there is always a part for lubrication and heat dissipation Serving oils migrates over the cylinder tracks, which is sprayed above the piston is and so in unavoidable wines reaches the compression area.

The invention is based on the object of the above-mentioned Nachceile of Avoid prior art.

In the case of a motor compressor of the type mentioned at the outset, this is done according to the invention achieved in that the motor-compressor has no moving parts leading outwards and equipped the entire engine including the pistons for dry running is.

This combination of features has the following advantages, among others: The overall dry run guarantees absolutely oil-free or liquid-lubricant-free compression.

The hermetic design avoids gas losses to the outside and allows a particularly small construction volume. There are no moving parts leading to the outside are available, a high level of freedom from maintenance is ensured.

In addition, this concept now also enables the use of a simple crank drive without cross head, which reduces the space requirement and the construction effort can be further reduced. It is particularly advantageous to use it as a dry store those that have a metallic bearing shell, on the inside of which a slidable one Layer of plastic is applied. For better heat dissipation, the Plastic layer of metal, e.g. bronze, pebbles can be embedded. Is preferred as a plastic base, polytetrafluoroethylene and polyimide.

For the motor insulation, cellulose-free all-plastic insulation is preferably used, which has been specially selected with regard to its chemical and thermal behavior. In many cases, terephthalate polyester has proven to be useful, especially for compressing gaseous SF6. In the case of highly corrosive media, a canned motor can be recommended, also for thermal reasons.

Depending on the area of application, the motor can be designed in such a way that it starts against pressure or can also work under negative pressure.

The compressor is preferably designed as an AC compressor, Power regulation as well as single or multi-stage design are basically possible. The intake path can be chosen so that the motor, in particular the stator package, at Operation is suction gas-cooled, or works without suction gas cooling. Both types can be advantageous on a case-by-case basis, depending on the application.

Such compressors can, for example, advantageously be used as an auxiliary unit for the oil-free compression of sulfur hexafluoride (SF 6) in connection with hermetically encapsulated SF 6 high-voltage switchgear as a pressure pump and for compressing other technical gases and vapors with predominantly high molecular weights, such as those used in particular in refrigeration technology will.

The invention is described below on the basis of an exemplary embodiment will be explained in more detail, from which further features and advantages of the invention result.

The accompanying drawings show: FIG. 1 the sectional view of a semi-hemetic motor compressor with a built-in motor that is not cooled by the vehicle; 2 shows the sectional view of a semi-hermetic notor compressor without suction gas cooling with a canned motor; 3 shows a motor compressor according to FIG. 1 or FIG. 2 with an additional heat exchanger for the purpose of better dissipation of the frictional heat generated during dry-running operation.

In Fig. 1 , the housing 1 of the encapsulation of the compressor and motor part is made of gas-tight, pressure-resistant cast iron or steel, which is provided with mounting openings, which are closed, for example, by screwed covers 2, which are also pressure-resistant and gas-tight. The built-in electric motor 3 used for driving, which has a high starting torque and therefore still starts reliably even against large pressure differences, is pressed into the housing 1 , whereby good dissipation of the motor occurring during operation is achieved to the outside. The stator winding 4 is designed without cell-water-containing, organic insulating materials, that is to say thermally highly resistant, and is provided with an impregnation also made of synthetic resin, for example based on polyurethane.

The electrical connection lines 5 of the built-in motor, which are also insulated with a thermally highly resistant, salt water-free material based on plastic, are connected from the inside to the power feed-through elements 6 arranged in the capsule or cover wall. The power feed-through bolts 6 are installed tightly and pressure-resistant in the capsule or cover wall according to 2p, but isolated from them.

The insulation can be achieved, for example, by melting these bolts in glass - or - as with many semi-hermetic machines already carried out '- using poorly conductive elastic sealing materials, for example on the basis of Silicone rubber, neoprene or other elastomers, which are special g'ogen SF 6 are sufficiently resistant. In the latter case, the In the enlarged section from Fig. 1 is shown, the elastic seal 7-between two solid insulating bodies 8 made of plastic, for example PTFE, placed on the metallic Current lead- through bolts 6 by screwing against each other be pressed to achieve the required sealing effect. The crank mechanism connected to the rotor 9 of the built-in motor 3 or eccentric shaft 10 is made of gray cast iron or steel with one by soft nitriding or similar methods for achieving high Surface treated with wear resistance and the running place. Such methods, according to which the piston pin zen 11 ku, are, for example, under the drawings Tenifer and Jmi: cerium treatment known. The storage of all rotating and swinging moving parts takes place in suitable, for this purpose especially under consideration management of the occurring load bucket contents with regard to Pressure, circumferential speed and temperature selected and sized dry running bearings 12. Particularly suitable are using w Pol7Utrafluorohylen with heat- dissipative, powdery beta coating and steel support dry running bearings made of shell. It can with advantage also stock on poly: undb «can be used in. In addition, imager shells made of porous sintered metal can also be used those with solid lubricants such as boron nitride, colybdenum the sulfide are incorporated. The connecting rods 13 used for power transmission are well known Wines carried out. The col- ben 14 are preferably made of a light metal alloy4 The seal between piston and cylinder and frictionless guidance of the piston is designed for dry running in a manner corresponding to the current state of the art, for example using piston seal 15 and guide rings 16 made of plastic of a suitable material selection.

The gas to be conveyed is sucked in by the compressor, which is designed as an alternating current compressor, for example, from the pistons via the suction work valves 17 and pushed out through the pressure work valves 18 into the compression chamber 19 . A connecting channel 21 with the suction chamber 22 is provided to recirculate the leakage gas resulting from the compression and flowing off into the crankcase 20. The connecting bore 24 is used to balance the gas between the crankcase 20 and the motor housing 23 .

The drive motor 3 , which is under suction pressure, is consequently always exposed to the influences of the conveying medium and is therefore designed to be SF 6-resistant as a whole.

For better dissipation of the frictional and compression heat occurring during operation as well as the heat lost from the engine, the compressor was blown from outside by a correspondingly dimensioned fan 25.

Motor compressors of the embodiment described according to FIG. 1 can in principle also be designed as suction gas-cooled compressors, with the conveying medium sucked in by the compressor entering the machine on the motor side in a manner corresponding to the current state of the art, flowing around the winding head of the built-in motor and passing through gas ducts on the Stator package is directed to the suction cup.

pig. In principle, FIG. 2 shows the same structure of the compressor as shown in FIG. 1 . In contrast to this, however, a canned motor 26 designed in a known manner is used here for the drive. This has the advantage that the winding 27 of the canned motor does not have to be made of insulation that is resistant to the medium to be conveyed. In addition, the expected heat development is lower because the heat loss from the external winding is not. more is delivered directly to the funding medium. Finally, in the event of damage caused, for example, by insulation faults or overstressing of the Ndtors, remedial measures can be carried out in a simpler manner because no intervention in the hermetically sealed machine is required. The can 29 surrounding the rotor 28 can, for example, be connected to the actual compressor housing in a tight and pressure-tight manner by means of screws.

A further variant of the motor compressor described under Fig. 1 and Fig. 2 consists in additionally improving the thematic behavior of these compressors by means of suitable measures for heat dissipation through internal and external heat exchange. This also has an advantageous effect on the service life behavior.

A possible solution to this is shown in Fig. 3. The only moderately moved Gaavolume located in the crankcase, which essentially stems from the piston leakage unavoidable during the compression cycle, is undesirably heated by the frictional and compression heat occurring during operation and by the engine losses. This heating caused by internal heat exchange is counteracted by lowering the overall temperature level and the resulting advantages through additional external heat exchange.

This can be done, for example, by connecting an appropriately sized ring line 30 at opposite points of the crankcase 20, into which a simple, forced-ventilated heat exchanger 32, blown from the outside by means of a fan 31 , with a circulation fan 33 downstream in the flow direction, which is also designed to run dry and hermetically encapsulated is 'built in'.

Claims (2)

Patent claims Hernetiech or neulhernetisch encapsulated Notor compressor for liquid-free, in particular oil-free, compression of dry or moist gases or vapors, whereby the compressor is designed as a piston compressor with one or more cylinders, characterized in that the Notorver.dichter has no moving parts leading to the outside and the entire engine including the pistons is equipped for dry running. 2. Notor compressor according to claim 1, characterized in that dry running bearings are installed, the sliding surface of which is entirely or partially made of polyethylene or polyaldehyde. 3. Notor compressor according to claim 1 or 2, characterized in that zuzilndent the notor insulation lying within the capsule is made cellulose-free. 4. Notor compressor according to one of the preceding claims, characterized # that it has a cross-headless crank drive. Notor compressor according to one of the preceding claims, characterized in that the electric drive motor is designed as a split motor. 6. Motor pre-sealer according to one of the preceding claims # dadure4.gekisiert that the motor can start up against pressure KanX. 7. Motor compressor according to one of the preceding claims, characterized in that the motor can work at negative pressure. 8. Motor compressor according to one of the preceding claims ,. characterized in that the compressor is a DC or AC compressor. 9. Motor compressor according to one of the preceding claims, characterized in that a ring line with a built-in heat exchanger and circulating pump or fan is attached to the Zurbel housing.