WO2005026548A1

WO2005026548A1 - Plunger piston compressor for refrigerants

Info

Publication number: WO2005026548A1
Application number: PCT/DK2004/000592
Authority: WO
Inventors: Jürgen Süss
Original assignee: Danfoss A/S
Priority date: 2003-09-13
Filing date: 2004-09-09
Publication date: 2005-03-24
Also published as: DE10342422A1; DE10342422B4

Abstract

The invention concerns a plunger piston compressor (1) for refrigerants, particularly for CO2, with a case-like housing, having a compressor block (2) with a compression section comprising a cylinder (13) as first housing element and a bottom part (3) as second housing element, the compressor block (2) and the bottom part (3) being connected with each other, and with a motor (25) with a drive shaft (23) located in the inner chamber (17). It is endeavoured to provide a high-pressure refrigerant compressor with a simple design, which is cost effective in manufacturing. For this purpose, it is ensured that in the area of their connection in parallel to the drive shaft (23), the compressor block (2) and the lower part (3) overlap axially on their complete circumference, the connection being formed in the overlapping area (47).

Description

Plunger piston compressor for refrigerants

The invention concerns a plunger piston compressor for re- frigerants, particularly for C0₂, 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.

Another refrigerant compressor is known from DE 195 16 811 C2. This compressor is enclosed by a relatively thin- walled case. The involved compressive strength merely permits the use of traditional refrigerants, for example, partially halogenated fluorohydrocarbons, for example

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. In or- der to decouple the vibrations, which occur because of the oscillating movement of the piston mass, from the housing and thus from the environment, the compressor itself is supported in the housing via a spring arrangement. Lately, carbon dioxide (C0₂) has become more and more used as refrigerant . C0₂ has the advantage of a better environmental compatibility, particularly with regard to ozone and greenhouse potential. Next to the incombustibility, an additional advantage is that also thermodynamically it is more favourable. Further, C0₂ 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.

However, with C0₂-systems, much higher working pressures occur. On the suction side they can be up to 70 bar and on the pressure side up to 160 bar. Accordingly, a pressure- proof design of the compressor is necessary, which requires an accordingly stable housing. This requirement requires great efforts and involves relatively high costs.

An oil-free, semi-hermetical piston compressor for small refrigerating capacities is known from the publication "Small Oil Free Piston Type Compressor for C0₂" by Heinz Baumann, published under "Proceedings of the International Purdue Compressor Technology Conference 2002, Purdue, USA, C25-3" . Further to the compressor block with a first shaft bearing, 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. During the rotation of the drive shaft, each piston pair performs a common reciprocating movement.

A further semi-hermetical two-cylinder piston compressor with a similar design is shown in "C0₂-Verdichter und - Ausrύstungen" , Die Kalte- und Klimatechnik 10/2002, pages 116 to 123. Also here, the motor housing is flanged onto the compressor block. A cover is fixed on the compressor block by means of several screws distributed in the circumferential direction.

The C0₂- 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.

With a plunger piston compressor as mentioned in the introduction, this task is solved in that in the area of their connection in parallel to the drive shaft, the compressor block and the lower part overlap axially on their complete circumference, the connection being formed in the overlapping area.

Thus, in principle, it is possible to transfer the basic design known from the hermetical household refrigerant compressors with compressor block, crankshaft drive and drive motor to the requirements of a high-pressure refrigerant compressor, thus achieving a simplified compressor design. Using C0₂ as refrigerant causes a higher volumetric refrigerating capacity than refrigerants based on hydrocarbons, which permits a reduction of the cylinder vol- ume and the piston diameter for a preset capacity. In connection with the increased total mass of the compressor caused by the correspondingly stable design of the housing, the reduced oscillating masses lead to a compressor design, in which the compression section no longer has to be mechanically decoupled from the housing by means of springs. The complete compressor works with relatively little vibration on the outside. Accordingly, it is no longer required to enclose the compressor block in a housing, but the compressor block can be used as housing ele- ment, which surrounds the inner chamber together with the bottom part. This again causes that also the bottom part must have a relatively stable design. It can for example be made as a thick-walled, deep-drawn part through cold forming of a steel plate with a thickness of approximately 8 mm. Such an embodiment, however, makes it difficult to make radial flanges, as known from the state of the art, for attaching the compressor block and the bottom part to each other by means of several clamp bolts distributed in the circumferential direction. A hermetical and undetach- able welded connection, which would by itself satisfy the stability requirements, would bring so much heat into the design that parts of the compressor would be damaged by the high temperatures occurring. These problems are solved in a simple manner in that the two housing elements are inserted in each other and attached to each other in the occurring overlapping area. This connection is so stable that the two housing elements cannot be pushed axially apart by the pressure ruling in the inner chamber. Further, it has to be so tight that the gas available in the inner chamber cannot flow out in an uncontrolled manner. No further requirements exist with regard to connection in the overlapping area. As described below, such a connec- tion can be realised relatively easily, also when both the compressor block and the bottom part are made to be relatively stable, that is, have relatively large wall thicknesses .

Preferably, the connection is free of auxiliary joining parts. This simplifies the mounting.

In a particularly advantageous embodiment, 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. In order to make the connection between the compressor block and the bottom part, 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 in- ner chambe .

In an alternative embodiment, it is ensured that in the overlapping area, the two housing elements are clamped to each other radially. Thus, the connection merely exists in the form of a frictional connection between the compressor block and the bottom part. When, however, a sufficient force causes this frictional connection, the resulting connection is sufficient to fix the bottom part reliably on the compressor block.

It is preferred that the radially outer housing element in the overlapping area is shrunk-fit or pressed onto the radially inner housing element. Thus, sufficient tension force can be achieved, so that the outer housing element can exert sufficiently large pressure forces on the inner housing element.

Both with a screwed connection and with a clamped connection, a generally auxiliary joining part free and unwelded connection of the housing of the compressor is achieved.

Preferably, 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. In principle, 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 .

It is preferred that 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.

It is preferred that 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.

When the connection is a clamped connection in the form of a shrink-fit, it is substantially simpler to heat the bottom part and to cool it during shrinking, as here there is no risk that elements of the compression section will be influenced.

It is preferred that, at least in the overlapping area, the bottom part has an increased wall thickness. The increased wall thickness improves the stability of the con- nection.

Preferably, the compressor block encloses the complete circumference of the cylinder. The compressor block in it- self 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 cylinder. During operation, the highest pressures exist in the cylinder. When 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 stability can be achieved in a simple manner. Of course, a liner can also be provided in such a bore, in order to im- prove the frictional behaviour between the piston and the inner cylinder wall .

Preferably, the cylinder has a lateral opening, which is connected with a compression chamber delimited by the cyl- inder and a piston displaceable in the cylinder, when the piston is in its lower dead point. In certain applications, systems working with a high-pressure refrigerant, particularly C0₂, 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 ca- pacity. In the embodiment shown, 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 C0₂, as the pressure ratio of the compressor is reduced, which will increase the efficiency. In housing-fixed compressor designs, this is particularly easily realised. 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. Merely in a piston position close to the lower dead point, the bore is not .closed by the piston, but has a connection to the compression chamber.

Preferably, the cylinder is delimited on one front side by a cylinder head, which comprises a suction chamber that is connected with the inner chamber. This connection ensures that refrigerant gas, which gathers in the inner chamber, can be sucked in during a suction stroke. Thus, an overfilling of the inner chamber with refrigerant gas is thus avoided. This causes that the pressure in the inner chamber can be kept at the level of the suction pressure.

Preferably, the drive shaft is only supported on one side of the motor. An alignment of various bearings to the same drive shaft can then be avoided. This is a further simplification of the design.

Preferably, the drive shaft is supported on the side of the motor, which is adjacent to the compression section. Thus, in a manner of speaking, the drive shaft is loaded "symmetrically" on both sides of the bearing. The motor acts upon one side. The crankshaft drive acts upon the other side. In both cases, the length of the drive shaft between the point of application of the force and the bearing is relatively short, so that the load on the bearing remains small, also when the various forces are not exactly the same. Preferably, the drive shaft has a counterweight, a connecting rod bearing being located between the counterweight and the bearing. Also this measure contributes to the reduction of the load of the bearing. The point of ap- plication of the connecting rod is located as close to the bearing as possible.

Preferably, the compressor block and the bottom part are joined by means of 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 clamping, respectively, can in principle be made gas tight, for example, by using an anaerobically hardening sealing material, like Loctite 577, or by inserting a me- tallic sealing. However, such a connection is still detachable, so that merely a semi-hermetically enclosed compressor is achieved. When, however, a welding or soldering seam is additionally provided, a hermetically enclosed compressor can be achieved. A large mechanical stability of the welding or soldering seam is not required. It can therefore be limited to a relatively thin layer on the outside of the housing. When making such a welding or soldering seam, there is no risk that the temperatures inside the housing will increase significantly, so that a damag- ing of components inside the housing must not anticipated.

Preferably, 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 chamber. Then, 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. Still, 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. During operation, the mounting opening is of course closed by the closing plate, which can also be screwed into the compressor block. Also here, an aneorobi- cally hardening sealing material can additionally be used. Also the use of an additional welding or soldering seam is possible.

Preferably, a glass feed-through is screwed into the compressor 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. When arranging the glass feed-through coaxially to the cylinder, 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.

Preferably, the connecting rod has an adjustable length. Then 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 adjustment of the dead volume by the use of differently thick sealings between the cylinder and the cylinder head is then no longer required. In the following, the invention is explained in detail on the basis of preferred embodiments in connection with the drawings, showing :

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 C0₂ 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. Further shown are a suction connection 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 manner. In the area of the bottom of the cup-shaped housing part 3 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. Further to a suction chamber 15, 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. For this purpose, the cover 7 and the valve plate 6 are fitted on the compressor block 2 by means of screw bolts 18. 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 2 .

The connecting rod 20 is divided in two, a cylindrical end 60 of the piston-side part of the connecting rod being arranged to be displaceable in a bore 61 of the crank-side part 62 of the connecting rod 20. After the dead volume setting (with the piston 14 in the upper dead point as shown) , these two parts of the connecting rod 20 are then retained in their final position, for example by clamping the crank-side connecting rod part 62 on the cylinder-side end 60. A traditionally used method for adjusting the dead volume by means of various thicknesses of a sealing located between the compressor block 2 and the valve plate 6 is not required.

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.

At its upper end, the compressor block 2 has a mounting opening 34, through which the drive shaft 23, the connecting rod 20 and counterweights 35 can be inserted during assembly. The inner wall of the opening 34 is provided with a thread 36. Thus, the closing plate 4 can be screwed into and close the opening 34. A sealing can, for example, be ensured by using a suitable, anaerobically hardening thread-sealing material, for example Loctite 577. 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.

Further, 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.

Through this chamber 51, the electrical supply wires for the drive motor are led to the stator 27. The thread 39 can also be tightened with an anaerobically hardening material or by means of a welding or soldering.

For the assembly of the compressor 1, 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. After inserting the piston 14 in the cylinder 13 and adjusting the dead volume, 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. 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 com- pressor block on part of its length. The resulting overlapping area 47 is closed in the circumferential direction. Due to the occurring high pressures, 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 Loctite 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. Thus, the sidewall 42 cannot expand with higher pressures, as it is retained in the recess from the radial outside. Thus, the risk of a radial movement of the cup-shaped bottom part 3 under the influence of the high pressures inside the housing can be reduced. 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-hermetic design. However, it would be possible to make the design hermetic by welding the gap along the screwed connections or the flanges of the cylinder head, respectively. For example, a hermetical sealing of the cup-shaped housing part 3 can be achieved by a circumferential welding seam along the contact line be- tween the housing part 3 and the block 2. 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.

Inside the cylinder 13, 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 .

With such 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. During the following compression movement, the piston 14 then compresses refrigerant gas, which has already been pre- compressed. This way of realising a multi-stage compression is energetically advantageous. As 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.

Claims

Patent Claims

1. Plunger piston compressor for refrigerants, particu-

5. larly for C0₂, 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 delim-0 iting a closed inner chamber, and with a motor with a drive shaft located in the inner chamber, characterised in that in the area of their connection in parallel to the drive shaft (23) , the compressor block (2) and the lower part (3) overlap axially on their com-5 plete circumference, the connection being formed in the overlapping area (47) .

2. Compressor according to claim 1, characterised in that the connection is free of auxiliary joining parts.0 3. Compressor according to claim 1 or 2 , characterised in that one of the two housing elements has an outer thread (45) and the other housing element has an inner thread (43) in the overlapping area (47) , the outer5 thread and the inner thread engaging in each other.

4. Compressor according to claim 1 or 2 , characterised in that in the overlapping area (47) , the two housing elements are clamped to each other radially.0 Compressor according to claim 4, characterised in that the radially outer housing element is shrunk-fit or pressed onto the radially inner housing element.

6. Compressor according to one of the claims 1 to 5, characterised in that the radially inner housing element in the overlapping area (47) has a circumferen- tial, radial flange (53) , which radially supports the outside of the housing element located radially outside in the overlapping area (47) , at least in the area of its front end.

7. Compressor according to claim 6, characterised in that the flange (53) has a conical recess (46) and that the front end of the radially outer housing element in the overlapping area (47) has a correspondingly conically chamfered front side.

8. Compressor according to one of the claims 1 to 7, characterised in that the bottom part (3) is located radially outside in the overlapping area (47) .

9. Compressor according to claim 8, characterised in that, at least in the overlapping area (47) , the bottom part (3) has an increased wall thickness.

10. Compressor according to one of the claims 1 to 9, characterised in that the compressor block (5) encloses the complete circumference of the cylinder (13) .

11. Compressor according to one of the claims 1 to 10, characterised in that the cylinder (13) has a lateral opening (49) , which is connected with a compression chamber (48) delimited by the cylinder (13) and a pis- ton (14) displaceable in the cylinder (13) , when the piston (14) is in its lower dead point.

12. Compressor according to one of the claims 1 to 11, characterised in that the cylinder (13) is delimited on one front side by a cylinder head (5) , which comprises a suction chamber (15) that is connected with the inner chamber (17) .

13. Compressor according to one of the claims 1 to 12, characterised in that the drive shaft (23) is only supported on one side of the motor (25) .

14. Compressor according to claim 13, characterised in that the drive shaft (23) is supported on the side of the motor (25), which is adjacent to the compression section.

15. Compressor according to one of the claims 13 or 14, characterised in that the drive shaft (23) has a counterweight (35) , a connecting rod bearing (21) being located between the counterweight (35) and the bearing (24) .

16. Compressor according to one of the claims 1 to 15, characterised in that the compressor block (2) and the bottom part (3) are joined by means of welding or soldering, the welding or soldering seam being limited to a radial outer area of the housing.

17. Compressor according to one of the claims 1 to 16, characterised in that the side of the compressor block (2) opposite the motor (25) has a mounting opening (34) closed by a closing plate (4) , through which opening the drive shaft (23), the counterweights (35) and the connecting rod (20) can be inserted in the inner chamber (17) .

18. Compressor according to one of the claims 1 to 17, characterised in that a glass feed-through (40) is screwed into the compressor block (2) , which is arranged coaxially to the cylinder (13) .

19. Compressor according to one of the claims 1 to 18, characterised in that the connecting rod (20) has an adjustable length.