EP2229532A1

EP2229532A1 - Reciprocating-piston compressor

Info

Publication number: EP2229532A1
Application number: EP08869359A
Authority: EP
Inventors: Eduardo Martin
Original assignee: Bitzer Kuehlmaschinenbau GmbH and Co KG
Current assignee: Bitzer Kuehlmaschinenbau GmbH and Co KG
Priority date: 2008-01-10
Filing date: 2008-12-30
Publication date: 2010-09-22
Anticipated expiration: 2028-12-30
Also published as: EP3557056A1; US20110005266A1; TR201909111T4; CN101910630B; DE102008004569A1; CN101910630A; US8690545B2; EP2229532B1; WO2009087071A1

Abstract

To improve a reciprocating-piston compressor for a refrigerant circuit, comprising a crankcase in which is arranged a collecting chamber for lubricant, a cylinder housing in which at least one reciprocating piston is movable in an oscillating fashion, a valve plate which closes off the cylinder housing and in which at least one inlet valve and one outlet valve are arranged, and a cylinder head in which are provided a suction gas conduit which runs to the inlet valve and a compressed gas conduit which leads away from the outlet valve, in such a way as to prevent excessive accumulations of lubricant, it is proposed that a lubricant suction duct is provided which has an inlet opening assigned to the collecting chamber and an outlet opening assigned to the suction gas conduit, and that the outlet opening (56) is situated in a region of the suction gas conduit in which, at least intermittently, a static pressure prevails which is lower than a static pressure in the collecting chamber for lubricant.

Description

reciprocating

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.

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 in that a Schmiermittelsaugkanal is provided which has an inlet opening associated with the collecting space and an outlet opening associated with the Sauggasführung, and that the outlet opening is located in a region of the Sauggasführung, in which at least temporarily static pressure lower than a static pressure in the collection space for lubricant.

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.

With regard to the inlet opening in the collecting space, no further details have been given so far.

In principle, it would be possible to arrange the inlet opening near a bottom of the collecting space, so that there is the possibility, whenever the static pressure in the region of the suction gas guide is lower than the static pressure in the collecting space to suck lubricant from the collecting space. However, it is even more advantageous if the inlet opening in the collecting space is arranged such 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.

In this case, it is particularly favorable if the inlet opening of the lubricant suction channel predetermines 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, for example, the minimum level of lubricant that can be achieved by suction 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.

In the drawing show:

Figure 1 is a schematic sectional view through a first embodiment with an excessively large amount of lubricant in a plenum of the crankcase.

FIG. 2 shows a section similar to FIG. 1 in the first embodiment with a lubricant quantity reduced and defined by lubricant extraction; FIG.

3 shows a section similar to Figure 1 through a second embodiment ..;

Fig. 4 is a section similar to FIG. 1 by a third embodiment and Fig. 5 is a section similar to FIG. 1 by a fourth embodiment.

A first exemplary embodiment of a reciprocating compressor according to the invention for refrigerants, illustrated in FIGS. 1 and 2, comprises a crankcase 10, in which a crank drive 12 is provided and which forms a collecting space 14 for lubricant 16, for example oil, which accumulates in the collecting space 14 the lubrication of the reciprocating compressor collects and forms a lubricant bath 18, the surface level 20 varies depending on the amount of lubricant 16 in the lubricant 18.

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 away from the discharge valve 34 pressure gas guide 44 are provided, the Sauggasführung 42 than from a suction gas connection 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 to the intake valve 32 in the valve plate 30 to be compressed refrigerant is supplied via the Sauggasführung 42 in the valve plate 30, namely, when the reciprocating piston 24 performs a suction movement, or the refrigerant in the Sauggasführung 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 behind each other, there is a risk that an excessively large amount of lubricant 16 accumulates in the collecting space 14 thereof and thus may be insufficient in other components of the system Lubricant is available or must be used in the system with an unnecessarily large amount of lubricant 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 P 1 which is below a pressure P 2 in the crankcase 10 can be reached. 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 until, as shown in FIG. 2, the surface level 20 of the lubricant bath 18 is at the level of the inlet opening 62.

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.

Because the suction gas flow 52 flowing through the nozzle 50 in the region 54 is lower than the pressure P2 in the crankcase 10, in particular in the collecting chamber 14, it is possible to suck lubricant through the lubricant suction channel 60 from the crankcase 10 as long as possible 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. 3, all those parts which are identical to those of the first embodiment, provided with the same reference numerals, so that reference may be made in full to the comments on the first embodiment in terms of their description.

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. 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 Pi in the region of the outlet opening 56 'in the channel 48, which is lower than the static pressure P ₂ in the crankcase 10, in particular in the collecting space 14, upstream of the suction opening 52', as the throttling device, there is a diaphragm 80, which then, 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 Pi in the region 54 'between the orifice 80 and the inlet valve 32 during the intake movement 24 drops short and thus sets a static pressure Pi at least briefly, 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 Pi is lower than the static pressure P. ₂ lubricant is then sucked out of the collecting space 14 via the lubricant suction channel 60 when the Surface mirror 20 is above the inlet opening 62.

In all the cases in which then the static pressure Pi in the channel 48 is at a same high pressure 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, since 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. 5, those parts which are identical to one of the preceding embodiments are also provided with the same reference numerals, so that with respect to the description of the same fully incorporated by reference to the statements to the preceding embodiments can.

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 Pi, namely, 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 Pi 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 Pi in the channel 48 is lower than the static pressure P ₂ in the crankcase 10, in particular in the collecting space fourteenth the same, in each case in adaptation to the suction gas stream 52 is adjustable.

The above-described variant of the third embodiment 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 Pl so far drops that a suction of lubricant 16 via the lubricant suction channel 60 takes place.

Alternatively, it is also conceivable to make the setting of the throttle valve 94 dynamically, that is to say, 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 operating cycles and then to 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

A reciprocating compressor for a refrigerant circuit, comprising a crankcase (10), in which a collecting space (14) for lubricant (16) is arranged, a cylinder housing (22) in which at least one reciprocating piston (24) is oscillatingly movable, a cylinder housing (22 ) final valve plate (30), in which at least one inlet valve (32) and an outlet valve (34) are arranged, and a cylinder head (40) in which a suction gas guide (42) extending to the inlet valve (32) and a discharge valve (34 ) are provided leading away from the compressed gas guide (44), that a Schmiermittelsaugkanal (60) is provided, which has a the collecting space (14) associated with the inlet opening (62) and the suction gas guide (42) associated outlet opening (56), and the outlet opening (56) lies in a region (54) of the suction gas guide (42) in which, at least temporarily, a static pressure (P1) prevails, the lower one as a static pressure (P2) in the collection space (14) for lubricant (16).

2. Reciprocating compressor according to claim 1, characterized in that the inlet opening (62) in the collecting space (14) is arranged so that it predetermines a predetermined position of a surface mirror (20) of a lubricant bath (18).

3. Reciprocating compressor according to claim 2, characterized in that the inlet opening (62) of the Schmierstoffaugkanals (60) by suction of lubricant (16) via the Schmiermittelsaugkanal (60) achievable lowest surface level (20) of the lubricant bath (18) pretends.

4. Reciprocating compressor according to one of the preceding claims, characterized in that the Schmiermittelsaugkanal (60) extends at least in sections by a in the crankcase (10) projecting tube (66).

5. Reciprocating compressor according to claim 4, characterized in that the tube (66) has the inlet opening (62).

6. Reciprocating compressor according to one of the preceding claims, characterized in that the lubricant suction passage (60) extends at least in sections in the crankcase (10).

7. Reciprocating compressor according to one of the preceding claims, characterized in that the outlet opening (56) of the Schmierstoffaugkanals (60) having region (54) in a constriction of a nozzle (50).

8. Reciprocating compressor according to one of claims 1 to 6, characterized in that the outlet opening (56) of the Schmierstoffaugkanals (60) having region (54) of the Sauggasführung (42) in the flow direction of the Sauggasstroms (52) behind a throttle device (80, 90 ) is in the suction gas guide (42).

9. reciprocating compressor according to claim 8, characterized in that the throttle device is designed as a diaphragm (80).

10. Reciprocating compressor according to claim 8, characterized in that the throttle device is an adjustable throttle device (90).

11. A reciprocating compressor according to claim 10, characterized in that the adjustable throttle device (90) alternates between substantially throttle-free time intervals and throttle effective time intervals.