EP2229532B1 - Reciprocating-piston compressor - Google Patents

Description

The invention relates to a reciprocating compressor for a refrigerant circuit, comprising a crankcase, in which a collecting space for lubricant is arranged, a cylinder housing in which at least one reciprocating piston is oscillating, a cylinder housing final valve plate in which at least one inlet valve and an outlet valve are arranged and a cylinder head in which a suction gas guide extending to the inlet valve and a pressurized gas guide leading away from the outlet valve are provided.

Such reciprocating compressors are from the GB-A-1 244 105 , the US 3,713,513 A , the EP 0 064 018 A1 , the US 2,150,487 A1 and the DE 197 21 44 U known. In all these reciprocating compressors a line between the crankcase and the suction gas guide is provided, which only serves to equalize the pressure.

In such reciprocating compressors, in particular when these are installed as reciprocating compressors for one of a plurality of compressor stages in a refrigerant circuit, there is the problem that accumulates depending on operating conditions in the crankcase, a larger amount of lubricant than intended.

As a result, either the total amount of lubricant required is higher than intended or other components of the refrigerant circuit, for example a downstream compressor, may not have enough lubricant available.

The invention is therefore based on the object to improve a reciprocating compressor of the generic type such that can avoid excessive accumulation of lubricant.

This object is achieved according to the invention in a reciprocating compressor of the type described above by the features of claim 1.

The advantage of the solution according to the invention is the fact that by such an embodiment, there is the possibility to suck lubricant from the plenum and supply the suction gas, which then conveys this lubricant through the reciprocating compressor and further promotes the pressure gas guide in the refrigerant circuit, for example, to the next compressor in the Refrigerant circulation.

This can be avoided in a simple and inexpensive manner that accumulates in the reciprocating compressor an excessively large amount of lubricant and thus thereby the problems already discussed occur.

The inlet opening in the collecting space is arranged so that it predetermines a predetermined position of a surface level of a lubricant bath.

This can already be ensured by arranging the position of the inlet opening that not too much lubricant is sucked out of the plenum, but that always in the plenum for the respective reciprocating compressor sufficient amount of lubricant remains.

This is particularly advantageous when the surface level of the lubricant bath drops below the inlet opening, since then in the case that the static pressure in the region of the Sauggasführung is lower than the static pressure in the crankcase, no suction of lubricant takes place, but simply a Aspirate the refrigerant already present in the crankcase.

The inlet opening of the lubricant suction channel provides a lowest surface level of the lubricant bath which can be achieved by suction of lubricant via the lubricant suction channel.

With regard to the course of the lubricant intake passage in the crankcase, no further details have been given so far.

Thus, an advantageous solution provides that the lubricant suction duct extends at least in sections through a tube projecting into the crankcase.

This pipe preferably has the inlet opening, so that the position of the inlet opening can also be defined by positioning the pipe in the crankcase.

Another advantageous solution provides that the lubricant suction duct extends at least in sections in the crankcase, that is, is formed in a wall of the crankcase and thus at least for this section no additional pipe is required.

Furthermore, with this solution, the position of the inlet opening of the lubricant suction channel can also be fixed in a simple manner and thus the minimum level of lubricant that can be achieved by suction can be determined.

In order to lower the static pressure in the region of the suction gas guide in which the outlet opening lies, it is preferably provided that the region having the outlet opening of the lubricant suction channel lies in a constriction of a nozzle.

As a result, when flowing through the nozzle suction gas in the constriction, a static pressure is generated, which is lower than the remaining pressure in the suction gas and thus can be a pressure differential between the static pressure in the crankcase, especially in the plenum, and the static pressure in the constriction of the To reach nozzle, whereby a suction of the lubricant from the collecting space takes place.

An alternative solution provides that the area of the suction gas guide having the outlet opening of the lubricant suction duct lies downstream of a throttle device in the suction gas guide in the flow direction of the suction gas flow.

Such a throttle device allows, for example behind the throttle point, at least temporarily, to lower the static pressure far enough that a pressure gradient between the plenum in the crankcase and the region of the outlet opening in the Sauggasführung occurs and thus takes place a suction of lubricant from the plenum.

In this case, for example, the throttle device as a constantly effective throttle point, for example, by a very cost-effective aperture, realize that, however, unfolds a constant throttle effect.

Another advantageous solution provides that an adjustable throttle device is provided, which opens up the possibility, for example, depending on the size of the suction gas flow, the throttle effect and thus adjust the static pressure in the area between the throttle point and the inlet valve.

In this case, the adjustable throttle device can be statically adjustable, that is, over a plurality of working cycles away have a constant setting.

Another solution which minimizes interference with the compressor performance is that the adjustable throttle device changes between substantially throttle-free time intervals and throttle-effective time intervals.

In this case, the throttle-effective time intervals can extend over less than one operating cycle of the reciprocating compressor or over several working cycles.

Preferably, the throttle-free intervals extend over several cycles in order to affect the compressor performance as little as possible.

Further features and advantages of the invention are the subject of the following description and the drawings of some embodiments.

Fig. 1

eine schematische Schnittansicht durch ein ersten Ausführungsbeispiel bei einer übermäßig großen Schmiermittelmenge in einem Sammelraum des Kurbelgehäuses;

Fig. 2

einen Schnitt ähnlich Fig. 1 beim ersten Ausführungsbeispiel bei einer durch Schmiermittelabsaugung reduzierten und definierten Schmiermittelmenge;

Fig. 3

einen Schnitt ähnlich Fig. 1 durch ein zweites Ausführungsbeispiel;

Fig. 4

einen Schnitt ähnlich Fig. 1 durch ein drittes Ausführungsbeispiel und

Fig. 5

einen Schnitt ähnlich Fig. 1 durch ein viertes Ausführungsbeispiel.

In the drawing show:

Fig. 1

a schematic sectional view through a first embodiment with an excessively large amount of lubricant in a plenum of the crankcase;

Fig. 2

similar to a cut Fig. 1 in the first embodiment with a reduced and defined by Schmiermittelabsaugung lubricant amount;

Fig. 3

similar to a cut Fig. 1 by a second embodiment;

Fig. 4

similar to a cut Fig. 1 by a third embodiment and

Fig. 5

similar to a cut Fig. 1 by a fourth embodiment.

A first embodiment of a reciprocating compressor according to the invention for refrigerants, shown in FIG Fig. 1 and 2 includes a crankcase 10 in which a crank drive 12 is provided and which forms a collection space 14 for lubricant 16, for example oil, which collects in the plenum 14 in the lubrication of the reciprocating compressor and forms a lubricant bath 18, the surface mirror 20 depending on Amount of the lubricant 16 in the lubricant bath 18 varies.

With the crankcase 10, a cylinder housing 22 is further connected, in which a reciprocating piston 24, driven by the crank drive 12 is movable up and down, wherein a cylinder chamber 26 is available for compressing refrigerant available.

The cylinder chamber 26 is closed on its side opposite the crank drive 12 by a valve plate designated as a whole by 30, in which at least one inlet valve 32 and at least one outlet valve 34 are provided per cylinder chamber 26.

On a cylinder chamber 26 opposite side of the valve plate 30 also a valve plate 30 cross-cylinder head 40 is provided, in which an inlet valve 32 reaching Sauggasführung 42 and a discharge valve 34 leading away pressure gas guide 44 are provided, the Sauggasführung 42 than from a suction 46th to the inlet valve 32 leading and, for example, predominantly directly above the valve plate 30 extending channel 48 is formed.

Depending on the working cycle of the reciprocating piston 24, refrigerant to be compressed is supplied to the inlet valve 32 in the valve plate 30 via the suction gas guide 42 in the valve plate 30, namely, when the reciprocating piston 24 performs a suction movement, or the refrigerant in the suction gas guide 42 remains substantially flowless, namely when the reciprocating piston 24 performs a compression movement and compresses the refrigerant in the cylinder 26 and finally discharges via the discharge valve 34 into the pressurized gas guide 44.

When operating such a reciprocating compressor in a complex system with a refrigerant circuit, in particular with a plurality of compressors arranged one behind the other, there is a risk that accumulates in the plenum 14 thereof an excessively large amount of lubricant 16 and thus in other components of the system, if necessary, too little lubricant Is available or in the system with an unnecessarily large amount of lubricant must be used to ensure flow-free operation in such a collection of lubricants in a reciprocating compressor.

To avoid this problem, the suction gas guide 42 is provided in the first embodiment with a nozzle 50 in which an acceleration of a suction gas stream 52 takes place before reaching the inlet valve 32.

In the nozzle 50, due to the acceleration of the suction gas flow 52, a region 54 of reduced pressure occurs in which a pressure P1 can be reached that is below a pressure P2 in the crankcase 10.

Provided in the region 54 is an outlet opening 56 of a lubricant suction channel 60, designated as a whole, whose inlet opening 62 is arranged in the collecting space 14 of the crankcase 10, at a distance A from a bottom 64 of the collecting space 14, so that only through the inlet opening 62 as long as lubricant 16 can be sucked in until, as in Fig. 2 represented, the surface mirror 20 of the lubricant bath 18 at the level of the inlet opening 62 is.

Preferably, the lubricant suction channel 60 is formed as a tube 66 which extends from the region 54 in the nozzle 50 to the inlet opening 62 and defined by the position of the inlet opening 62, the position of the surface mirror 20 of the lubricant 18, in which just a suction of lubricant is possible via the lubricant suction channel 60, while with further lowering of the surface mirror 20 no more suction of lubricant is possible.

Characterized in that at the nozzle 50 through-flowing suction gas stream 52 in the region 54, the pressure P1 is lower than the pressure P2 in the crankcase 10, in particular in the collecting chamber 14, there is the possibility to suck lubricant through the lubricant suction channel 60 from the crankcase 10 as long as long the surface level 20 is higher than the inlet opening 62 and until the surface level 20 is equal to the inlet opening 62 of the lubricant suction channel 60.

The sucked into the nozzle 50 lubricant is supplied through the suction gas flow 52 via the inlet valve 32 of the cylinder chamber 26 and ejected from this again with the compressed refrigerant via the outlet valve 34 and thus discharged via the compressed gas guide 44, for example, conveyed with the pressurized gas to the next refrigerant compressor.

In a second embodiment of a reciprocating compressor according to the invention, shown in FIG Fig. 3 , All those parts which are identical to those of the first embodiment, provided with the same reference numerals, so that with respect to the description of which reference may be made in full to the comments on the first embodiment.

In contrast to the first embodiment, the lubricant suction channel 60 'is not formed by a tube 66, but molded into the crankcase 10, such as a wall portion 70 thereof, such that the lubricant suction passage 60' in the wall portion 70 extends to the inlet port 62 also has an aperture 72 the valve plate 30 passes through and finally passes through an opening 74 of the nozzle 50, which extends to the outlet opening 56 in the nozzle 50.

In a third embodiment of a reciprocating compressor according to the invention, shown in FIG Fig. 4 are also those parts which are identical to those of the first or second embodiment, provided with the same reference numerals, so that the description thereof can be fully incorporated by reference.

In the third embodiment, the lubricant suction channel 60 extends in the tube 66, from the inlet opening 62 to an outlet opening 56 ', which in this embodiment lies in the region on a side of the valve plate 30 facing the suction gas guide 42, so that the outlet opening 56'. immediately adjacent to the provided in the cylinder head 40 channel 48.

In order to generate a static pressure P ₁ in the channel 48 in the region of the outlet opening 56 'which is lower than the static pressure P ₂ in the crankcase 10, in particular in the collecting space 14, the outlet opening 56' upstream of the suction gas flow 52 is a throttling device Aperture 80 is provided, which, when the reciprocating piston 24 performs an intake movement enlarging the cylinder chamber 26, leads to a pressure drop downstream of the orifice 80, so that the static pressure P ₁ in the region 54 'between the orifice 80 and the inlet valve 32 during the suction movement 24 falls short term and thus a static pressure P _{1 is} at least temporarily set, which is lower than the pressure P ₂ in the crankcase 10, in particular in the collecting space 14, so that during this time during which the static pressure P _{1 is} lower than the static pressure P ₂ lubricant is then sucked out of the collecting space 14 via the lubricant suction channel 60, if the surface mirror 20 is above the inlet opening 62.

In all the cases in which then the static pressure P ₁ in the channel 48 is at an equal pressure, such as the static pressure P ₂ in the crankcase 10 or higher, there is no suction of lubricant 16 from the plenum 14, which, however, no Disadvantage represents, as already in each cycle repeated temporary suction of lubricant through the lubricant suction channel 60 in the region 54 is sufficient to keep the surface level 20 of the lubricant bath 18 in the region of the inlet opening 62 in the time average.

In a fourth embodiment of a reciprocating compressor according to the invention, shown in FIG Fig. 5 , Likewise, those parts which are identical to one of the preceding embodiments are provided with the same reference numerals, so that with regard to the description of the same, reference may be made in full to the comments on the preceding embodiments.

Also in this embodiment, the outlet opening 56 is located on the valve plate 30 and in the area 54 ', which is located between an adjustable throttle device 90 and the inlet valve 32.

The throttle device 90 in this case comprises a passage 92, which is adjustable with an adjustable throttle valve 94, for example a pivotable about an axis 96 throttle valve 94, with respect to its throttling action for the suction gas stream 52, wherein, for example, an actuator 98 is provided.

This can in principle achieve the same effect as with the aperture 80, but with the difference that the throttle device 90 is adjustable by rotating the throttle valve 94 with respect to its throttling effect on the suction gas stream 52, so that there is the possibility to adjust the pressure P ₁ , and in accordance with the suction gas flow 52, so that, for example, in certain phases of the intake movement of the reciprocating piston 24, the static pressure P ₁ drops so far that it is lower than the static pressure P ₂ in Crankcase 10, in particular in the collecting space 14 and thus the possibility exists to suck lubricant from the collecting space 14 and to supply the suction gas stream 52 for further transport.

This solution has the advantage that the adjustability of the throttle valve 94 by means of the actuator 98 according to the operating conditions of the reciprocating compressor, the periods at which the static pressure P ₁ in the channel 48 is lower than the static pressure P ₂ in the crankcase 10, in particular in the plenum 14 thereof, in each case in adaptation to the suction gas stream 52 is adjustable.

The variant of the third embodiment described above thus provides that the setting of the throttle valve 94 remains constant over a plurality of working cycles and thus the adjustment can be made so that at least temporarily, the static pressure P1 drops so far that a suction of lubricant 16 via the lubricant suction channel 60 takes place.

Alternatively, however, it is also conceivable to make the adjustment of the throttle flap 94 dynamically, that is, for example, adjust the throttle valve 94 to a specific value of the throttling of the suction gas flow 52 in the course of each operating cycle in order to maintain the static pressure P1 in the region 54 'for a certain period of time. lower.

However, it is also conceivable not to use the throttle valve 94 at each operating cycle for throttling the suction gas flow 52, but, for example, to throttle the suction gas flow 52 with the throttle valve 94 only during one or fewer working cycles and then control the throttle valve 94 for a plurality of operating cycles. that no throttling is done, so that During many cycles corresponding periods no throttling of the suction gas flow 52 through the throttle 94 is performed to not affect the compressor performance, and only at the expense of a short-term impairment of the compressor power throttling the Sauggasstroms 52 with the throttle valve 94 takes place to lubricant through the Schmiermittelsaugkanal 60 aspirate the collecting space 14, while subsequently the throttle valve 94 is opened again for a considerable period of time, in turn, to have the full compressor capacity available.

Claims (9)

1. Reciprocating piston compressor for a refrigerant circuit, comprising a crankcase (10), a collecting chamber (14) for lubricant (16) being arranged in said crankcase, a cylinder housing (22), at least one reciprocating piston (24) being movable in an oscillating manner in said cylinder housing, a valve plate (30) closing the cylinder housing (22), at least one inlet valve (32) and one outlet valve (34) being arranged in said valve plate, and a cylinder head (40), a suction gas duct (42) running to the inlet valve (32) and a compressed gas duct (44) leading away from the outlet valve (34) being provided in said cylinder head,
   characterized in that a lubricant suction conduit (60) is provided, said conduit having an inlet opening (62) associated with the collecting chamber (14), that the inlet opening (62) is arranged in the collecting chamber (14) at such a distance (A) from a base (64) of the collecting chamber (14) that in order to avoid excessive accumulations of lubricant it predetermines a lowest surface level (20) of a lubricant bath (18) achievable as a result of lubricant being drawn off by suction via the lubricant suction conduit (60), said surface level representing an amount of lubricant sufficient for the reciprocating piston compressor, that the lubricant suction conduit (60) has an outlet opening (56) associated with the suction gas duct (42), that the outlet opening (56) is located in an area (54) of the suction gas duct (42) where such elements (50, 80, 90) are provided that a static pressure (P1) prevails at least temporarily, said pressure being lower than a static pressure (P2) in the collecting chamber (14) for lubricant (16), and that the reciprocating piston compressor feeds the lubricant drawn off by suction via the lubricant suction conduit (60) to the suction gas duct (42), conveys the lubricant through the reciprocating piston compressor and conveys it further in the lubricant circuit via the compressed gas duct (44).
2. Reciprocating piston compressor as defined in one of the preceding claims, characterized in that the lubricant suction conduit (60) extends at least in sections through a pipe (66) projecting into the crankcase (10).
3. Reciprocating piston compressor as defined in claim 2, characterized in that the pipe (66) has the inlet opening (62).
4. Reciprocating piston compressor as defined in any one of the preceding claims, characterized in that the lubricant suction conduit (60) extends in the crankcase (10) at least in sections.
5. Reciprocating piston compressor as defined in any one of the preceding claims, characterized in that the area (54) having the outlet opening (56) of the lubricant suction conduit (60) is located in a narrow point of a nozzle (50).
6. Reciprocating piston compressor as defined in any one of claims 1 to 4, characterized in that the area (54) of the suction gas duct (42) having the outlet opening (56) of the lubricant suction conduit (60) is located behind a throttling device (80, 90) in the suction gas duct (42) in flow direction of the stream (52) of suction gas.
7. Reciprocating piston compressor as defined in claim 6, characterized in that the throttling device is designed as a screen (80).
8. Reciprocating piston compressor as defined in claim 6, characterized in that the throttling device is an adjustable throttling device (90).
9. Reciprocating piston compressor as defined in claim 8, characterized in that the adjustable throttling device (90) alternates between time intervals essentially free of throttling and time intervals with active throttling.

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