Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
  • F04B39/00—Component parts, details, or accessories, of pumps or pumping systems specially adapted for elastic fluids, not otherwise provided for in, or of interest apart from, groups F04B25/00 - F04B37/00
  • F04B39/0094—Component parts, details, or accessories, of pumps or pumping systems specially adapted for elastic fluids, not otherwise provided for in, or of interest apart from, groups F04B25/00 - F04B37/00 crankshaft
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
  • F04B39/00—Component parts, details, or accessories, of pumps or pumping systems specially adapted for elastic fluids, not otherwise provided for in, or of interest apart from, groups F04B25/00 - F04B37/00
  • F04B39/12—Casings; Cylinders; Cylinder heads; Fluid connections
  • F04B39/121—Casings

Definitions

• the invention concerns a plunger piston compressor for re- frigerants, particularly for C0 2 , with a case-like housing, having a compressor block with a compression section comprising a cylinder as first housing element and a bottom part as second housing element, the compressor block and the bottom part being connected with each other and delimiting a closed inner chamber, and with a motor with a drive shaft located in the inner chamber .
• Such a refrigerant compressor is known from US 2,583,583.
• the motor is grip-held in the bottom part.
• the drive shaft of the motor is supported in both the bottom part and in the compressor block.
• On the compressor block is fixed a cylinder, in which a piston is arranged to be reciprocating.
• the piston is driven by the drive shaft via a connecting rod.
• R134a or hydrocarbons, like propane or isobutene, which have even less greenhouse potential.
• Such refrigerant compressors have relatively low working pressures, which, on the suction side, are for example lower than 5 bar.
• the compressor itself is supported in the housing via a spring arrangement .
• carbon dioxide (C0 2 ) has become more and more used as refrigerant.
• C0 2 has the advantage of a better environmental compatibility, particularly with regard to ozone and greenhouse potential.
• an additional advantage is that also thermodynamically it is more favourable.
• C0 2 has a substantially higher volumetric refrigerating capacity. This substantially reduces the refrigerant volume, which is required to produce a certain refrigerating capacity, in relation to refrigerants, which are based on hydrocarbons.
• the compressor housing comprises a cylindrical tube element, in which the stator of the drive motor is fixed, a second bearing element for the drive shaft, and a motor-side housing cover.
• the individual parts of the housing bear on each other with flange surfaces and are fixed to each other by several screw bolts distributed on the circumference.
• a corresponding compressor as known from EP 0 378 967, comprises a compressor block with four cylinders, each offset by 90°.
• the compressor has a so-called Scotch-Yoke drive, in which each two pistons facing each other are connected by means of a yoke, which again is connected with a crank pin of a drive shaft via a sliding piece.
• the movement directions of the two sliding pieces or yokes, respectively, are here perpendicular to each other.
• each piston pair performs a common reciprocating movement.
• the C0 2 - compressors known from the state of the art are characterised by the design characteristics of the traditional several -cylinder, semi-hermetical compressors, which are dimensioned for large refrigerating capacitiess and accordingly have a higher mechanical stability.
• the pistons of the individual cylinders are moved by a drive shaft, which is supported in at least two main bearings. These bearings, which are located in different housing parts, must be oriented accurately in relation to each other during mounting, which involves relatively large ef- forts.
• the invention is based on the task of providing a high- pressure refrigerant compressor with a simple design and cheap in manufacturing.
• a one-sided bearing has until now not been regarded as an option for high-pressure refrigerant compressors, as the high pressures result in a corresponding load of the shaft and thus of the bearing. Surprisingly, it has turned out, however, that also with high-pressure refrigerants a onesided bearing is sufficient.
• the drive shaft is supported on the side of the motor, which is adjacent to the compression section.
• the drive shaft is, in a manner of speaking, "symmetrically" loaded on both sides of the bearing.
• the motor On one side, the motor is engaging.
• the crankshaft drive On the other side, the crankshaft drive is engaging.
• the length of the drive shaft between the force contact points and the bear- ing is relatively short, so that the load on the bearing remains small, also when the individual forces are not exactly the same.
• the drive shaft has a counterweight, and a connecting rod bearing is located between the counterweight and the bearing. Also this measure contributes to reducing the load on the bearing.
• the contact point of the connecting rod is as closely adjacent to the bearing as possible .
• the compressor block can be used as a housing element, which surrounds the inner chamber together with the bottom part. This again causes that the bottom part must have a relatively stable design. It can, for example, be made as a thick-walled deep-drawn part by cold forming of a steel plate with a thickness of approximately 8 mm.
• connection in the overlapping area.
• such a connection can be made in a relatively simple manner, also when both the compressor block and the bottom part are made to be relatively stable, that is, have relatively large wall thicknesses.
• connection is free of auxiliary joining parts. This simplifies the mounting.
• one of the two housing elements has an outer thread and the other housing element has an inner thread in the overlapping area, the outer thread and the inner thread engaging in each other.
• the two housing elements are put together and turned in relation to each other. The engagement between the outer thread and the inner thread is sufficient for preventing an axial disassembling of the two housing elements, also with high pressures in the inner chamber.
• connection merely exists in the form of a frictional connection between the compressor block and the bottom part.
• a sufficient force causes this frictional connection, the resulting connection is sufficient to fix the bottom part reliably on the compressor block.
• the radially outer housing element in the overlapping area is shrunk-fit or pressed onto the ra- dially inner housing element.
• sufficient tension force can be achieved, so that the outer housing element can exert sufficiently large pressure forces on the inner housing element.
• the radially inner housing element in the overlapping area has a circumferential, radial flange, which radially supports the outside of the housing element located radially outside in the overlapping area, at least in the area of its front end.
• an increased pressure in the inner chamber involves the risk that the housing expands radially. This expansion might cause that the radially outer housing element expands in the overlapping area, thus reducing the length of the overlapping area, which again would have negative consequences for the clamping forces in the overlapping area.
• Such an expansion is avoided in that the radially outer housing element is radially retained from the outside in the area of its front end.
• the flange has a conical recess and that the front end of the radially outer housing element in the overlapping area has a correspondingly conically chamfered front side.
• the outer housing element and the inner housing element thus get a suitable engagement with each other.
• the bottom part is located radially outside in the overlapping area.
• the bottom part is the housing element with the simplest design, compared with the compressor block. Therefore, it is simpler to provide an inner thread here, as there are no disturbing parts.
• the connection is a clamped connection in the form of a shrink-fit, it is substantially simpler to heat the bot- torn part and to cool it during shrinking, as here there is no risk that elements of the compression section will be influenced.
• the bottom part has an increased wall thickness.
• the increased wall thickness improves the stability of the connection.
• the compressor block encloses the complete circumference of the cylinder.
• the compressor block in itself has a certain stability, which is required to resist the pressure in the inner chamber. This stability of the compressor block is utilised also for adopting the cylin- der.
• the highest pressures exist in the cylinder.
• the cylinder is not made as a separate component, which is connected with the compressor block, but as a bore in the compressor block, a high mechanical sta- bility can be achieved in a simple manner.
• a liner can also be provided in such a bore, in order to improve the frictional behaviour between the piston and the inner cylinder wall.
• the cylinder has a lateral opening, which is connected with a compression chamber delimited by the cylinder and a piston displaceable in the cylinder, when the piston is in its lower dead point.
• a high-pressure refrigerant particularly C0 2
• systems working with a high-pressure refrigerant, particularly C0 2 may, for energetic reasons, require a supply of refrigerant to the compression chamber, whose pressure is between the suction pressure and the high pressure of the refrigeration system. This is particularly the case, when it is not required to reduce the pressure of the complete amount of previously compressed refrigerant gas in order to provide the required refrigerating capacity.
• this "medium pressure gas” is led into the compression chamber at the end of a suction stroke, that is, in a piston position, which is close to the lower dead point.
• This way of realising a multi-stage compression is energetically advantageous in connection with C0 2 , as the pressure ratio of the compressor is reduced, which will increase the efficiency.
• the medium pressure gas can namely be supplied direct from the outside to the compression chamber through a bore made in the compressor block, whose opening into the compression chamber is covered by the piston during almost the complete piston stroke.
• the bore is not closed by the piston, but has a connection to the compression chamber.
• the cylinder is delimited on one front side by a cylinder head, which comprises a suction chamber that is connected with the inner chamber.
• a cylinder head which comprises a suction chamber that is connected with the inner chamber.
• the compressor block and the bottom part are connected by welding or soldering, the welding or soldering seam being limited to a radial outer area of the housing.
• the connection via a thread engagement or a radial tension, respectively, can in principle be made gas-tight, for example by using an anaerobically hardening sealing material, like Loctite 577, or by inserting a metallic sealing.
• an anaerobically hardening sealing material like Loctite 577
• a metallic sealing like as Loctite 577
• such a connection is still detachable, so that only a semi-hermetical compressor is concerned.
• a welding or soldering seam is added, a hermetically enclosed compressor can be achieved.
• the welding or soldering seam is not supposed to have a large mechanical strength. It can therefore be limited to a relatively thin layer on the outside of the housing.
• the side of the compressor block opposite the motor has a mounting opening closed by a closing plate, through which opening the drive shaft, the counterweights and the connecting rod can be inserted in the inner cham- ber.
• the bearing can be made in one piece with the compressor block, that is, no additional connection measures are required between the outer wall of the compressor block and a component adopting the bearing.
• the bearing is accessible from two sides. On the side facing the motor, there are no limitations anyway. On the opposite side the accessibility exists through the mounting opening.
• the mounting opening is of course closed by the closing plate, which can also be screwed into the compressor block.
• an aneorobi- cally hardening sealing material can additionally be used. Also the use of an additional welding or soldering seam is possible.
• a glass feed-through is screwed into the com- pressor block, which is arranged coaxially to the cylinder.
• This glass feed-through permits the connection of electrical lines of the motor with electrical supply lines from the outside, without abandoning the tightness of the housing.
• the bores, which are required for the cylinder and the glass feed-through can be made without requiring a placing or directional change of the compressor block in the corresponding production machine.
• the connecting rod has an adjustable length.
• the dead volume in the compression chamber can be set in a relatively simple manner.
• the piston is taken to its upper dead point.
• the drive shaft is turned to a position, which corresponds to the upper dead point of the piston.
• the connecting rod is then adjusted exactly to the resulting length.
• An adaptation of the dead chamber caused by the use of differently thick sealings between the cylinder and the cylinder head is then no longer required.
• Fig. 1 a perspective, overall view of the compressor
• Fig. 2 a vertical section through a first embodiment of the compressor
• Fig. 3 a vertical section through a part of a modified embodiment of the compressor
• Fig. 1 shows a one-cylinder, semi-hermetic C0 2 compressor 1 with a central compressor block 2, which forms part of the compressor housing. Further components are connected with the compressor block 2 and delimit the inside of the compressor. These are, firstly, a cup or bell-shaped bottom part 3 and a closing plate 4, secondly a cylinder head 5, which comprises a valve plate 6 with integrated suction and pressure chambers and a cylinder head cover 7.
• the compressor block 2 and the bottom part 3 are two housing elements, which, together with the closing plate 4 delimit an inner chamber 17.
• a suction connec- tion 8 through which the gaseous refrigerant is sucked in, and a pressure connection 9 for discharging the compressed refrigerant.
• Both connections are connected with the openings of the valve plate in a pressure tight man- ner.
• fixing devices 10 are located, which permit a safe mounting of the compressor 1 on a base by insertion of rubber block supports 11.
• the sectional view according to Fig. 2 shows the design of the compressor according to Fig. 1.
• the compressor block 2 forms the upper part of the compressor housing. It comprises a projection 12, in which a cylinder 13 is formed. Together with a piston 14 and the valve plate 6, this cylinder delimits the compression chamber of the compressor 1, which cannot be seen here, as the piston 14 is in its upper dead point.
• the valve plate comprises a pressure chamber (not shown) and suction and pressure openings, which connect the compression chamber with the suction chamber and the pressure chamber (not to be seen in the section) .
• a pressure equalising bore 16 connects the suction chamber 15 with the inner chamber 17 inside the compressor housing.
• the cylinder head cover 7 closes the suction chamber 15 and the pressure chamber towards the environment.
• the cover 7 and the valve plate 6 are fitted on the compressor block 2 by means of screw bolts 18.
• the piston 14 Via a ball joint 19, the piston 14 is connected with a connecting rod 20, whose crank-side connecting rod eye 21 is rotatably supported around an eccentrically arranged crank pin 22 of the drive shaft 23.
• the drive shaft 23 again is rotatably supported in a radial bearing 24 formed in the compressor block 2, and is driven by a motor 25. In the area of its upper end, the drive shaft 23 has a diameter expansion, with which it is axially supported on the housing of the radial bearing 24.
• the connecting rod 20 is divided in two, a cylindrical end
• the motor 25 comprises a rotor 26, which is fixed on the drive shaft 23, and a stator, which is fixed on the compressor block 2 by means of fixing elements (not shown) .
• An oil pump 28 is located in the bottom part of a through bore 29 of the rotor 26, and immerses with its inlet opening 30 into the oil sump 31 at the bottom of the compres- sor housing.
• the oil pump 28 is a centrifugal pump, and, in a manner known per se, it supplies lubricating oil into a blind hole bore 32 of the drive shaft 23 and from there to openings 33 in the bearing areas of the compressor to be lubricated.
• the required oil quantity in the compressor is substantially reduced in relation to known, housing- fixed compressors, but also in relation to spring- decoupled designs, as the inlet opening 30 of the oil pump can be located very close to the bottom of the cup-shaped bottom part 3, and the inner volume of the compressor on a whole is minimised.
• the compressor block 2 has a mounting opening 34, through which the drive shaft 23, the connect- ing rod 20 and counterweights 35 can be inserted during assembly.
• the inner wall of the opening 34 is provided with a thread 36.
• the closing plate 4 can be screwed into and close the opening 34.
• a suitable, anaerobi- cally hardening thread-sealing material for example Loc- tite 577, can for example, ensure a sealing.
• a tight welding by means of a circumferential welding seam which, however, does not have to have a large mechanical strength, or a tight soldering, can also be used.
• the compressor block 2 has a projection 37, in which is formed an opening 38 with an inner thread 39.
• the opening is made for adopting a glass feed-through element 40 with metallic pins 50 isolated from the housing, and ends in a chamber 51, which is a part of the inner chamber 17.
• the thread 39 can also be tightened with an anaerobically hardening material or by means of a welding or soldering.
• the drive shaft 23 is inserted through the opening 34 in the compressor block 2 together with the connecting rod 20 and the counterweights 35.
• the cylinder head 5 is attached.
• the openings 34 and 38 are now closed by means of the closing cover 4 and the glass feed-through 40.
• the rotor 26 is pushed onto the shaft 23 and the oil pump 28 is inserted in the rotor.
• the compressor After fixing the stator 27 on the block 2, the compressor merely has to be closed by means of the cup-shaped bottom part 3, which is mounted over the motor 25 so as to axially overlap with the compressor block on part of its length.
• the resulting overlapping area 47 is closed in the circumferential direction.
• the bottom part 3 requires a sufficient wall thickness. Typically, it is made as a deep-drawn component from an 8 mm steel plate. It serves as cover for the motor 25, the adoption of the oil sump 31, and as carrier for the fixing arrangements 10, which can be fixed by welding near a bottom 41 of the bottom part 3. Beside the bottom 41, the bottom part 3 has a cylinder-shaped side part 42, on whose inner side is formed an inner thread 43 near the open end of the bottom part 3. In order to maintain the required stability, also in the area of the inner thread 43, the wall thickness of the upper section 44 of the sidewall 42 is increased. The inner thread 43 interacts with an outer thread 45 formed on the compressor block 2 and is also tightened with an anaerobically hardening sealing material, for example Loc- tite 577.
• an anaerobically hardening sealing material for example Loc- tite 577.
• the upper front face of the sidewall 42 is preferably conically chamfered towards the outside and, after fin- ished assembly; it is supported on a correspondingly conical recess 46 on a circumferential, radial flange 53 of the block 2.
• the sidewall 42 cannot expand with higher pressures, as it is retained in the recess from the radial outside.
• Test pressures of more than 350 bar will therefore not harm the housing. Due to the detachable and dismountable housing parts 3, 4, 40 and the cylinder head 5, the compressor described until now represents a semi-hermetical design.
• the design hermetical by welding the gap along the screwed connections or the flanges of the cylinder head, respectively.
• a circumferential welding seam along the contact line between the housing part 3 and the block 2 can achieve a hermetical seal- ing of the cup-shaped housing part 3.
• the resulting pressure forces will be adopted by the screwed connection.
• the welding seam merely has a sealing function, and can be made with a small heat energy input.
• Fig. 3 shows a modified embodiment of a compressor without cylinder head, bottom part and mounting cover. The same parts have the same reference numbers as described in Fig. 2.
• the piston 14 is in its lower dead point. Accordingly, the compression chamber 48 can be seen in its full size. It can also be seen that the cylinder is located in the compressor block 2, or, more precisely, in the projection 12, and is accordingly supported on its en- tire circumference by the compressor block 2.
• a bore 49 with a connection enlargement 52 is led through the projection 12.
• the bore 49 ends in the compression chamber 48 in such a manner that the piston 14 releases it, when the piston is in the area of its lower dead point .
• a lateral bore it is possible to supply refrigerant gas to the compression chamber 48 with a pressure, which lies between the suction pressure and the high pressure of the system connected with the compressor.
• the piston 14 then compresses refrigerant gas, which has already been pre- compressed.
• This way of realising a multi-stage compression is energetically advantageous.
• the pressure ratio of the compressor is lower, the efficiency increases. It is particularly easy to realise here, as the bore 49 can be led directly to the outside through the compressor block 2. As soon as a compression stroke begins, the bore 49 is closed. Thus, a pressure increase outside the compression chamber 48 is practically impossible.

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• 2003
  • 2003-09-13 DE DE10342421A patent/DE10342421A1/de not_active Withdrawn
• 2004
  • 2004-09-09 US US10/571,233 patent/US20070110599A1/en not_active Abandoned
  • 2004-09-09 CN CNA200480033405XA patent/CN1878961A/zh active Pending
  • 2004-09-09 WO PCT/DK2004/000591 patent/WO2005026547A1/en active Application Filing

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