EP3507493B1 - Compressor - Google Patents

Description

The present invention relates to a compressor, in particular for compressing refrigerant, according to the preamble of patent claim 1.

Compressors are used in many areas of modern life. An example of this is the generation of compressed air (compressed air) for a variety of purposes, such as for filling tires, breathing apparatuses, etc. Another example is the compression of (in particular technical) gases for storage and transportation thereof, for example in corresponding gas bottles. Examples of this are nitrogen, oxygen, acetylene and other gases which are used, for example, as combustion or protective gases in welding processes. Furthermore, compressors are often used in particular for the compression or compression of refrigerants, such as R134a (tetrafluoroethane) or R744 (CO ₂ ), particularly due to the increasing air conditioning of rooms and vehicles and also due to the constantly increasing need for cooling goods.

From the EP 0 054 966 A2 is, for example, a refrigerant compressor with a housing enclosing a compressor section and a drive section containing an electric motor, a crankshaft driven by the rotor of this electric motor, an oil pipe, the upper end of which is connected to an opening of a mounting base portion which is connected to a bearing of the crankshaft is fixed to be substantially concentric therewith and the lower end of which is immersed in a lubricating oil collected in the housing, and with a screw-type oil supply device which is arranged in the oil pipe and connected at its upper end to the end of the crankshaft and the like the lower end is immersed in the lubricating oil, the crankshaft being supported essentially horizontally, the oil tube being curved and the screw-type oil supply device consisting of a coil spring, the adjacent turns of which are in close contact with one another, are known.

In many applications, in particular refrigeration and air conditioning applications, the compressors used are reciprocating compressors, examples of which are used Axial piston compressors and radial piston compressors are mentioned. Such compressors generally have a compressor housing, in which at least one piston is arranged so that it can move back and forth in a cylinder or a cylinder bore. The pistons are often driven by an electric motor. Such compressors often have oil sump lubrication, the oil sump in the compressor in an installation or working position extending upwards from a lower side of the housing or lower edge of the housing to a certain oil level. It is important to ensure that the motor does not dip into the oil sump, which means that the corresponding compressors have to be relatively large.

Starting from the prior art discussed above, it is an object of the present invention to provide a compressor, in particular a compressor for compressing gases, in particular for compressing refrigerant, which has a smaller or more compact size compared to compressors according to the prior art.

This object is achieved by a compressor according to claim 1.

According to the invention, a corresponding compressor, in particular a compressor for compressing gases, furthermore in particular for compressing refrigerant, has a compressor housing and at least one piston which is arranged to move back and forth in a cylinder and which is driven by an electric motor. The compressor also has oil sump lubrication, the oil sump in the compressor in a working position or an installation position extending from an underside or lower edge of the housing to a predetermined oil level or oil level. The compressor has a lubrication, in particular pressure circulation lubrication, with a lubricant delivery device, the lubricant delivery device being connected to the oil sump and provided for the suction of lubricant from the oil sump. The electric motor has a housing which delimits a housing interior in which the electric motor is arranged, the electric motor including the housing extending into the oil sump of the compressor and the housing having a suction opening which is equipped with a suction device which is used to extract air from the Lubricant entering the interior of the housing is provided is connected, wherein the suction device and the lubricant delivery device are implemented by a single gear pump, which has a first and a second suction opening, the first and the second suction opening being separated from one another, and wherein the first suction opening for suction into the interior of the housing provided lubricant is provided, and the second suction opening is provided for sucking in lubricant from the oil sump. In other words, the electric motor of the compressor is arranged in a so-called dry sump, since oil or lubricant which enters the interior of the housing (in particular leakage oil) can be extracted via the suction opening arranged in the housing.

This means that the engine or parts of the engine are not in the oil, but the engine is located in the dry sump. This avoids a possible condenser effect of the oil, which could possibly lead to fault currents, in particular when the compressor is started, and would thus increase the risk of failure for the compressor.

In a further possible embodiment, both the suction device and the lubricant delivery device, which are implemented by a single pump, are implemented by an internal gear pump. This is a robust construction.

In a further possible embodiment, the gear pump has at least two gear wheels, which have gear teeth, the gear teeth having a tooth width, which is measured in particular at their base or at their half extent, the first and second suction openings being separated from one another by at least one tooth width are separated.

The gear pump can have a pressure kidney for the discharge of pumped oil. Furthermore, the gear pump can have a first and a second suction kidney as the first and second suction opening, the first suction kidney being in communication or fluid communication with the housing interior via a first suction pipe and the second suction kidney being connected via a second suction pipe which is located in the oil sump of the Compressor stretches in, is connected to the oil sump. It should be noted at this point that the first suction kidney and / or the second suction kidney alternatively directly with the Housing interior / oil sump can be connected or can be arranged on or in the same. The position of the suction kidneys is determined by the relative amount of the fluid to be extracted at the respective suction openings.

In one possible embodiment, in normal operation the gear pump has a working direction of rotation or conveying direction in which the medium to be conveyed is conveyed, the first suction kidney, viewed in relation to the working direction, having a smaller extent in the circumferential direction than that in FIG Regarding the working direction seen second suction kidney Due to the position of the suction kidneys relative to an expansion space in the pump, the respective volumes and the delivery behavior of the pump can be influenced, the above arrangement leading to the safe maintenance of the dry sump with good absorption of the lubricant still required from the oil sump. This also ensures good lubrication performance, with the dry sump remaining oil-free.

The internal gear pump preferably has a pump housing that limits it at least in sections to the outside, and an internal rotor and an external rotor, both of which are provided with teeth. The inner rotor is usually designed as an external gear, i.e. as a gear which has a toothing whose tooth tips are oriented radially outwards, whereas the outer rotor is usually designed as an internal gear, that is to say as a wheel-shaped device which extends radially inwards is recessed and has an inward toothing from the outside. The first and the second suction kidneys are arranged in the pump housing and are separated from one another by at least a distance which corresponds to a width of an intermeshing pair of teeth of the outer rotor and the inner rotor. Both the first and the second suction kidneys are preferably arranged in a pump cover, that is to say on the same side of the pump.

The compressor optionally has a suction gas feed into the compressor housing, through which gas to be compressed, in particular refrigerant, is fed into the compressor housing, and a suction gas outlet of the suction gas feed inside the compressor housing, the suction gas outlet being arranged on a top side of the compressor. In a further possible embodiment, the housing has one Suction gas inlet, via which suction gas can enter the housing interior, in particular for cooling the electric motor, the suction gas inlet being arranged on an upper side of the housing interior. This enables installation or operation of the compressor in an inclined position up to relatively large angles of inclination.

Alternatively or additionally, the suction gas outlet is arranged in such a way that the suction gas enters it tangentially to the compressor housing. The tangential suction gas inlet into the compressor housing or the compressor outer housing already achieves an oil separation of over 90% of the oil in the suction flow. In the further course of gravity separation takes place until the suction gas reaches the suction gas inlet of the housing (the suction opening in the motor housing). In the housing, further oil, which is still in the suction gas, is sprayed onto the stator by the centrifugal action of the rotor, where it can coagulate and run to the bottom of the housing. Here it is sucked off by the suction device or dry sump pump. In this respect, the two housings also form an excellent oil separator.

Furthermore, the compressor can have a high-pressure volume into which the compressed medium, in particular refrigerant, is expelled after the compression process, the high-pressure volume being associated with a pulsation damper for damping pulsations in the expelled medium.

In an optional embodiment, the compressor is designed to compress CO ₂ .

Further features of the invention are specified in the subclaims.

• Fig. 1 eine Schnittansicht einer ersten Ausführungsform eines erfindungsgemäßen Verdichters, wobei die Schnittebene in eine axiale Richtung des Verdichters gerichtet ist;
• Fig. 2 einen Ausschnitt der Fig. 1;
• Fig. 3 eine Ansicht des Verdichters der Fig. 1, wiederum in Schnittdarstellung, wobei die Schnittebene jedoch in eine radiale Richtung gerichtet ist;
• Fig. 4 eine Detailansicht der Fig. 1;
• Fig. 5 wiederum ein Schnitt in einer radialen Richtung des Verdichters, wobei sich die Schnittebene durch einen Ölpumpendeckel desselben erstreckt;
• Fig. 6 eine Draufsicht auf eine Ölpumpe des Verdichters, wobei der Ölpumpendeckel transparent dargestellt ist;
• Fig. 7 eine Antriebswelle des Verdichters mit Kolben und Ausgleichsgewicht gemäß dem in den vorangehenden Figuren dargestellten Verdichter;

The invention is described below with reference to the accompanying drawings using exemplary embodiments. The drawings show:

• Fig. 1 a sectional view of a first embodiment of a compressor according to the invention, wherein the sectional plane is directed in an axial direction of the compressor;
• Fig. 2 a section of the Fig. 1 ;
• Fig. 3 a view of the compressor of the Fig. 1 , again in a sectional view, but the cutting plane is directed in a radial direction;
• Fig. 4 a detailed view of the Fig. 1 ;
• Fig. 5 again a section in a radial direction of the compressor, the section plane extending through an oil pump cover thereof;
• Fig. 6 a plan view of an oil pump of the compressor, the oil pump cover being shown transparently;
• Fig. 7 a drive shaft of the compressor with piston and balance weight according to the compressor shown in the previous figures;

The compressor 10 shown in the figures is a reciprocating piston compressor, more precisely a radial piston compressor, which (compare in particular to this Figure 7 ) has six pistons 12, which are arranged to move back and forth in corresponding cylinders (not shown). The compressor has a compressor housing 14, which in the embodiment shown completely encloses it. An electric motor 16, which is enclosed by means of a housing 18, is used to drive the pistons 12. The compressor 10 described is a compressor 10 with oil sump lubrication, an oil sump 20 (in a working or operating position or an installation position of the compressor 10) extending from an underside 22 of the housing to a predetermined oil level (oil level) 24 extends. The electric motor 16 is arranged in a housing interior 26 delimited by the housing 18 and extends together with the housing 18 into the oil sump 20 of the compressor 10. The housing interior 26 is oil-free or oil sump-free. As an alternative to the feature that the housing interior 26 is oil-free or oil sump-free, one could also say that the electric motor 16, which is arranged in the housing interior 26, is arranged in a dry sump in the housing interior 26.

The housing 18 has a suction opening 28 in the form of a recess which is connected or fluid communication by means of a first suction line 30 to a suction device or pump in the form of an internal gear pump 32. The first suction line 30 connects the suction opening 28 to a first suction opening in the form of a first suction kidney 34 of the internal gear pump 32. This ensures reliable suction of oil, which can in particular penetrate into the housing 18 from the lubricant circuit of the compressor.

The internal gear pump 32 also has a second suction opening in the form of a second suction kidney 36, which is in fluid communication with the oil sump 20 via a second suction line 38. This ensures reliable delivery of oil by the internal gear pump 32.

It remains to be mentioned at this point that the compressor 10 has a pressure circulation lubrication which, by means of the lubricant delivery device by delivering lubricant (oil) from the oil sump, which in the present embodiment is formed by the internal gear pump 32, lubricates the lubrication points, in particular bearing points and the like. In the embodiment described here, the internal gear pump 32 serves at the same time as a suction device, by means of which oil that possibly penetrates into the interior 26 of the housing can be sucked off. The double function of the internal gear pump 32 ensures, in a structurally simple design, both good lubricating performance and reliable maintenance of the dry sump in which the electric motor 16 is arranged, that is to say that the oil sump freedom of the interior 26 of the compressor 10 is reliably ensured.

The internal gear pump 32 has a pressure kidney 40 for discharging the conveyed oil, which is in communication or fluid communication via corresponding lines (not shown) with lubrication points, in particular bearing points which are to be lubricated.

The internal gear pump 32 has a pump housing 42 with a pump cover 44. Both the pump housing 42 and the pump cover 44 limit the Internal gear pump 32 to the outside. In the described embodiment of a compressor 10 according to the invention, both the first suction kidney 34 and the second suction kidney 36 and the pressure kidney 40 are each arranged in the pump cover 44 in the form of corresponding cutouts. In alternative embodiments, it would also be conceivable that the first suction kidney 34 and / or the second suction kidney 36 and / or the pressure kidney 40 is / are not arranged on the pump cover 44 but on the pump housing 42, for example on a side opposite the pump cover 44. In the described embodiment, the first suction kidney 34 and the second suction kidney 36 are spatially spaced apart. The distance is at least a width of one tooth of either an external rotor 46 of the internal gear pump 32 or an internal rotor 48 of the internal gear pump 32 (which are identical). The width of the tooth is defined as the extension at the base of the tooth. This ensures that the volume assigned to the first suction kidney 34 and the volume assigned to the second suction kidney 36 in the pump, which are formed by the outer rotor 46 and the inner rotor 48, remain separate from one another and the inner gear pump 32, provided that they are in a working position. Direction of rotation (in the embodiment described here, the pump rotates to the right, ie from the first suction kidney 34 in the direction of the second suction kidney 36), first sucks off oil from the housing interior 26 and then draws oil from the oil sump.

As mentioned above, the gear pump has the working direction of rotation in normal operation and the first suction kidney, viewed in relation to the working direction, which corresponds to the first suction kidney 34 in the embodiment described here, has a smaller extent in the circumferential direction than that in FIG With regard to the working direction, the second suction kidney corresponds to the second suction kidney 36 in the embodiment described here.

If one were to reverse the direction of rotation of the pump, the large chamber corresponding to the larger (second) suction kidney 36 would first be filled with oil, and when the opening associated with the first (smaller) suction kidney 34 is then reached, the oil has the chance to to escape that direction. This results in a lower delivery rate. This applies when the main oil is drawn in from the chamber assigned to the second suction grille and the dry sump only brings a subset of the lubricant. The partial amount is in particular 0% - 50%, preferably 0% - 40%, further preferably 0% - 25%.

The compressor 10 also has a suction gas supply 50, which passes from the outside through the compressor housing 14 and opens into the interior of the compressor housing 14. The suction gas supply 50 is arranged in such a way that a suction gas outlet 52 of the suction gas supply 50 ensures tangential gas guidance in the compressor 10 for improved oil separation. The suction gas outlet 52 is accordingly arranged such that the suction gas enters the same tangentially to the compressor housing 14. The suction gas introduced into the compressor housing 14 is then guided via a suction gas inlet 54 in the form of a recess in the housing 18 into the housing interior 26 in which the electric motor 16 is arranged, the suction gas passing through the electric motor 16 and thereby cooling it. This is particularly out Figure 2 can be seen where the suction gas flow is indicated by corresponding arrows 56, 58 and 60. After flowing through the electric motor 16, the suction gas is drawn into the cylinders of the compressor 10 in order to then be discharged into a high-pressure volume 62 in the compressed state.

The high-pressure volume 62 has a pulsation damper 64 for damping pulsations which are caused by the compression process, in particular the discharge of the pressurized gas or refrigerant into the high-pressure volume 62. At the same time, this ensures low noise.

In the embodiment described here, the compressor 10 is designed as a compressor for CO ₂ and is constructed in a hermetic construction. In alternative embodiments, a semi-hermetic design of the compressor is conceivable. It can therefore be stated that a compressor 10 according to the present invention can be designed both hermetically and semi-hermetically.

At this point it should be noted that the pistons 12 in the embodiment described above are made of steel. This leads to a significantly reduced thermal expansion compared to aluminum pistons. Steel pistons are particularly suitable for absorbing or coping with the forces that arise when CO _{2 is used} as a refrigerant. The low thermal also ensures Expansion of the steel for high operational reliability even at high compression ratios, where a large amount of heat is expected.

At this point it is explicitly on the Figures 3 , 5 and 6 referenced, from which the arrangement of the first suction kidney 34 and the second suction kidney 36 and the pressure kidney 40 is clearly visible. Out Figure 6 the interior of the internal gear pump 32 can also be recognized, since the pump cover 44 is shown transparently in this figure. This makes it very easy to see the interaction between the outer rotor 46 and the inner rotor 48, which bring about the oil production. In particular, it leaves out Figure 6 recognize the distance between the first suction kidney 34 and the second suction kidney 36, which, as already mentioned above, is at least one tooth width.

Ultimately, it should be noted that high pressure is present only in the high-pressure volume 62 and the associated high-pressure line 66, which serves to discharge the compressed medium from the compressor. Otherwise, the entire remaining interior of the compressor housing 14 is at low pressure (suction pressure).

Out Fig. 7 the construction of the drive device (drive shaft 68) including the pistons, which are moved back and forth in a radial direction by means of connecting rods 70, can be seen. In order to increase the smooth running, a mass balance takes place by means of suitable mass balance weights 72 and 74.

Reference symbol list

10th

compressor

12

piston

14

Compressor housing

16

Electric motor

18th

Enclosure

20th

Oil sump

22

Bottom of the housing

24th

Oil level

26

Housing interior

28

Suction opening

30th

First suction line

32

Internal gear pump

34

First suction kidney

36

Second suction kidney

38

Second suction line

40

Pressure kidney

42

Pump housing

44

Pump cover

46

Outrunner

48

Internal runner

50

Suction gas supply

52

Suction gas outlet of the suction gas supply 50

54

Suction gas inlet

56, 58, 60

arrow

62

High pressure volume

64

Pulsation damper

66

High pressure line

68

drive shaft

70

Connecting rod

72.74

Balance weight

Claims (11)

1. Compressor (10), in particular a refrigerant compressor, with a compressor housing (14) and at least one piston (12) which is arranged in a reciprocating manner in a cylinder and which is driven by an electric motor (16), wherein the compressor (10) comprises an oil sump lubrication, the oil sump (20) in the compressor (10) extending from a housing lower side (22) to an oil level (24), the compressor (10) comprising a forced feed lubrication with a lubricant conveying device, the lubricant conveying device being connected to the oil sump and being provided for sucking lubricant from the oil sump, wherein the electric motor (16) comprises a housing (18) with a housing interior (26) defined by the housing (18), the electric motor (16) is arranged in the housing interior (26) and the electric motor (16) together with the housing (18) extends into the oil sump (20) of the compressor (10), characterized in that
   the housing (18) comprises a suction opening (28) connected with a suction device provided for the suction of lubricant entering the housing interior (26), the suction device and the lubricant conveying device being implemented by a single gear pump, which has a first and a second suction opening, wherein the first and the second suction opening are separated from one another, and wherein the first suction opening is provided for the suction of lubricant entering the housing interior (26), and the second suction opening is provided for the suction of lubricant from the oil sump (20).
2. Compressor (10) according to claim 1, characterized in that the gear pump is an internal gear pump (32).
3. Compressor (10) according to one of the preceding claims, characterized in that the gear pump has at least two gearwheels which comprise gearwheel teeth, the gearwheel teeth comprising a tooth width which is measured in particular at their base or at half their extension height, the first and the second suction opening being separated from one another by at least one tooth width.
4. Compressor (10) according to one of the preceding claims, characterized in that the gear pump comprises a pressure kidney (40) for discharging conveyed oil, and in that the gear pump comprises a first suction kidney (34) as a first suction opening and a second suction kidney (36) as a second suction opening, wherein the first suction kidney (34) communicates with the housing interior (26) via a first suction line (30) and wherein the second suction kidney (36) communicates with the oil sump (20) via a second suction line (38) which extends into the oil sump (20) of the compressor (10).
5. Compressor (10) according to one of the preceding claims, characterized in that the gear pump in normal operation has an operating direction of rotation and that, seen in relation to the operating direction, the first suction kidney (34) has a smaller extension in the circumferential direction than, seen in relation to the operating direction, the second suction kidney (36) has.
6. Compressor (10) according to one of claims 2 to 5, characterized in that the internal gear pump (32) comprises a pump housing (42) which at least in sections delimits the internal gear pump (32) outwardly, and comprises an internal rotor (48) and an external rotor (46), both of which are provided with teeth, wherein the first and the second suction kidney (34, 36) are arranged in the pump housing (42), in particular a pump cover (44), and wherein the first and second suction kidneys (34, 36) are separated from each other by at least a distance corresponding to the width of an intermeshing pair of teeth of the outer rotor (46) and the inner rotor (48).
7. Compressor (10) according to one of the preceding claims, characterized in that the compressor (10) comprises a suction gas supply (50) into the compressor housing (14), through which gas to be compressed, in particular refrigerant, is supplied into the compressor housing (14), and a suction gas outlet (52) of the suction gas supply (50) in the interior of the compressor housing (14), the suction gas outlet being arranged on a compressor top side.
8. Compressor (10) according to one of the preceding claims, characterized in that the compressor (10) comprises a/the suction gas supply (50) into the compressor housing (14), through which gas to be compressed, in particular refrigerant, is supplied into the compressor housing (14), and a/the suction gas outlet (52) of the suction gas supply (50) in the interior of the compressor housing (14), the suction gas outlet (52) being arranged in such a way that the suction gas enters the compressor housing (14) tangentially to the latter.
9. Compressor (10) according to one of the preceding claims, characterized in that the housing (18) comprises a suction gas inlet (54), via which suction gas can, in particular for cooling the electric motor (16), enter the housing interior (26), the suction gas inlet being arranged on an upper side of the housing interior (26).
10. Compressor (10) according to one of the preceding claims, characterized in that the compressor (10) comprises a high-pressure volume (62) into which the compressed medium, in particular refrigerant, is ejected after the compression process, and in that the high-pressure volume (62) comprises a pulsation damper (64) for damping pulsations in the ejected medium.
11. Compressor (10) according to one of the preceding claims, characterized in that the compressor (10) is adapted to compress CO₂ as the medium to be compressed or the compressor (10) comprises CO₂ as the medium to be compressed.

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