CRANKSHAFT

Abstract

A crankshaft (1) for a refrigerant compressor, the crankshaft (1) at least comprising a cylindrical shaft element (2), a crankpin (3) for driving a compressor piston of the refrigerant compressor, and means for conveying lubricant from a lower end region (4), facing away from the crankpin (3), of the shaft element (2) in the direction of the crankpin (3), in order to supply lubricant to movable parts of the refrigerant compressor, wherein at least one surface section of a surface of the crankshaft (1) comprises at least one flow disruptor, which flow disruptor is, based on the geometry and/or characteristics thereof, configured to break up vapor bubbles and/or gas bubbles in the lubricant flowing around the crankshaft (1) in an operating state of the refrigerant compressor.

Claims

1. A crankshaft for a refrigerant compressor, the crankshaft at least comprising a cylindrical shaft element, a crankpin for driving a compressor piston of the refrigerant compressor, and a conveyor conveying lubricant from a lower end region, facing away from the crankpin, of the shaft element in the direction of the crankpin, in order to supply lubricant to movable parts of the refrigerant compressor, wherein at least one surface section of a surface of the crankshaft comprises at least one flow disruptor, which flow disruptor is, based on the geometry and/or characteristics thereof, configured to break up vapor bubbles and/or gas bubbles in the lubricant flowing around the crankshaft in an operating state of the refrigerant compressor.

2. The crankshaft according to claim 1, wherein the conveyor conveying lubricant is embodied by a helical conveying groove of the shaft element, which conveying groove circles the longitudinal axis of the shaft element, wherein the conveying groove is part of the surface section and comprises at least one flow disruptor.

3. The crankshaft according to claim 2, wherein at least one flow disruptor is arranged on a base of the conveying groove and/or on a wall of the conveying groove.

4. The crankshaft according to claim 1, wherein the conveyor conveying lubricant is embodied by a bore that is preferably eccentrically arranged, particularly preferably running transversely to the longitudinal axis of the shaft element, wherein an inner surface of the bore, which inner surface defines the bore, is part of the surface section and comprises at least one flow disruptor.

5. The crankshaft according to claim 1, wherein an outer envelope surface of the shaft element is part of the surface section and comprises at least one flow disruptor.

6. The crankshaft according to claim 5, wherein at least one flow disruptor is arranged in a free section of the outer envelope surface of the shaft element, wherein the shaft element has in the region of the free section a smaller diameter than in the region of a mounting section of the shaft element and/or of the end region, whereas the mounting section is used to mount the crankshaft in the refrigerant compressor.

7. The crankshaft according to claim 1, wherein at least one flow disruptor is embodied as a raised section and/or a recess of the surface section.

8. The crankshaft according to claim 1, wherein at least one of the flow disruptors is embodied by a groove.

9. The crankshaft according to claim 8, wherein the groove has a smaller groove depth than the conveying groove.

10. The crankshaft according to claim 8, wherein the groove is embodied to be helical and circles the longitudinal axis of the shaft element.

11. The crankshaft according to claim 10, wherein the groove has a smaller pitch, preferably by at least a factor of 10, than the conveying groove.

12. The crankshaft according to claim 1, wherein at least one of the flow disruptors is embodied by a furrow or score, preferably one group each of furrows or scores arranged parallel to one another.

13. The crankshaft according to claim 1, wherein at least one flow disruptor is embodied by at least one adhesive dot and/or welded dot, preferably by a plurality of adhesive dots and/or welded dots, which at least one adhesive dot and/or welded dot protrudes from the surface section of the crankshaft.

14. A compressor, preferably a refrigerant compressor, having a crankshaft according to claim 1.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0039] The invention will now be explained in greater detail with the aid of exemplary embodiments. The drawings are by way of example and are intended to demonstrate, but in no way restrict or exclusively describe, the inventive concept.

[0040] In this matter:

[0041] FIG. 1 shows a crankshaft according to the invention;

[0042] FIG. 2 shows the crankshaft from FIG. 1 in a side view;

[0043] FIG. 3 shows the crankshaft from FIG. 1 in a top view;

[0044] FIG. 4 shows a crankshaft according to the invention with a flow disruptor embodied as a groove;

[0045] FIG. 5 shows a further crankshaft according to the invention with a flow disruptor embodied as a groove;

[0046] FIG. 6 shows another crankshaft according to the invention with flow disruptors embodied as a group of scores;

[0047] FIG. 7 shows a bore 7 in a cut-away view of the end region of the crankshaft; and

[0048] FIG. 8 shows an expanded view of portion A depicted in FIG. 7.

WAYS OF EMBODYING THE INVENTION

[0049] FIGS. 1 through 3 show a crankshaft 1 according to the invention for a compressor, preferably a refrigerant compressor, having a cylindrical shaft element 2, a crankpin 3, and a transition element 20 that is arranged between the crankpin 3 and the shaft element 2 and serves to balance the crankshaft 1. The crankshaft 1 comprises, in the form of a conveying groove 5, means for conveying lubricant in order to convey lubricant from a lower end region 4, facing away from a crankpin 3, of a shaft element 2 in the direction of the crankpin 3.

[0050] The conveying groove 5 is embodied as a helical groove and circles a longitudinal axis 6 of the cylindrical shaft element 2. It thereby begins in the end region 4 of the shaft element 2, namely in an outlet opening 21, and merges into a pass-through opening 19 in a mounting section 9 of the shaft element 2, which mounting section 9 is adjacent to the transition element 20.

[0051] The outlet opening 21 renders it possible that lubricant which was conveyed via a bore 7 (not illustrated)see FIGS. 7 and 8from a lubricant sump into the interior of the shaft element 2 in an operating state of the refrigerant compressor can exit the shaft element 2 and spill over into conveying groove 5 in order to be further conveyed in the direction of the crank pin 3. For this purpose, the outlet opening 21 is connected to the bore 7. The bore 7 itself is preferably an eccentric bore running transversely to the longitudinal axis 6 of the shaft element 2, which eccentric bore extends in the shaft element 2 from a bottom base surface 22 of the shaft element 2. A longitudinal axis 17 of the bore 7 thereby forms an angle of approximately 10 with the longitudinal axis 6 of the shaft element 2 in the exemplary embodiment shown. In the operating state of the refrigerant compressor, the crankshaft 1 extends, with the end region 4 thereof, but at least with the base surface 22, into the lubricant sump, so that lubricant is conveyed to the outlet opening 21 via the bore 7 by the rotation of the shaft 1.

[0052] From FIGS. 2, 7, and 8, it can be seen that the crankshaft 1 comprises in the end region 4 of the shaft element 2 an additional bore 16 that enables a supply of lubricant to a bearing of the refrigerant compressor in which the crankshaft 1 is rotatably mounted by means of the end region 4. A longitudinal axis 18 of the additional bore 16 thereby essentially runs orthogonally to the longitudinal axis 6 of the shaft element 2.

[0053] Via the pass-through opening 19 into which the conveying groove 5 merges, the lubricant ultimately reaches the crankpin 3, which is typically embodied as a hollow cylinder and is therefore open in an upward direction (see FIG. 3). The conveyed lubricant can exit the crankshaft 1 via the crankpin 3 and lubricate the movable components of the compression mechanism, for example a compressor piston, or a bearing of the refrigerant compressor in which the crankshaft 1 is rotatably mounted by means of the mounting section 9.

[0054] The lubricant then runs off from the compression mechanism or from the movable components of the refrigerant compressor and returns to the lubricant sump, where it is available for renewed conveying in the direction of the crankpin 3. One portion of the lubricant thereby runs off via an inside of a compressor housing; another portion via the crankshaft 1, or more precisely, via a surface of the crankshaft 1. The term surface denotes the entirety of all boundary surfaces of the crankshaft 1. In particular, the lubricant can run off via an outer envelope surface 8 of the shaft element 2 or via inner surfaces 12 of the bore 7 or the pass-through opening 19 on the crankshaft 1.

[0055] As a result of the high rotational speed of the crankshaft 1 in the operating state of the refrigerant compressor 1, there occurs, particularly in the boundary layer between the surface of the crankshaft 1 and the lubricant, a significant decrease in the static pressure in the lubricant, which in turn leads to a markedly lower evaporation temperature of the lubricant. The operating temperature present in the housing interior in the operating state of the refrigerant compressor is therefore already sufficient to evaporate portions of the lubricant in the region of the boundary layer so that gas bubbles can form in the lubricant. This phenomenon is referred to as cavitation, and can result in the components of the refrigerant compressor being damaged by the implosion of the gas bubbles formed. In connection with compressors, such gas bubbles can cause a failure of the supply of lubricant to the movable components of the compressor that are to be lubricated, since the gas bubbles formed can partially or even fully block the means for conveying lubricant.

[0056] To counteract the bubble formation described above, and to destabilize gas bubbles that have already formed and cause them to collapse, it is provided according to the invention that at least one surface section of the surface of the crankshaft 1 comprises at least one flow disruptor. The geometry and/or the characteristics of the flow disruptor causein combination with a corresponding positioning of the at least one flow disruptor or at least one of the flow disruptorsthe gas bubbles in the lubricant flowing around the crankshaft 1 to be destabilized and broken up.

[0057] For example, the flow disruptors can be realized by adhesive dots 15 in the interior of the conveying groove 5, namely on a base 11 and/or a wall of the conveying groove 5 (see FIGS. 1 and 2). In this manner, lubricant that enters into the conveying groove 5 is reliably freed of gas bubbles. A clogging of the conveying groove 5 itself or of the pass-through opening 19 with gas bubbles can thus be avoided. Similarly, the arrangement of the adhesive dots 15 can be provided on the inner surface 12 of the bore 7 in order to already free the lubricant of potential gas bubbles during the inflow into the crankshaft 1.

[0058] However, the at least one flow disruptor or at least one of the flow disruptors can also be embodied by an additional groove 13, which groove 13 is arranged on the outer envelope surface 8 of the shaft element 2. In particular, the groove 13 can be arranged in a free section 10 of the shaft element 2, wherein the free section 10 extends between the end region 4 and the mounting section 9 of the shaft element 2 and comprises a slightly smaller diameter than the mounting section 9 and/or the end section 4. Embodiments of the crankshaft 1 according to the invention with a groove 13 that is arranged in the free section 10 and functions as a flow disruptor are illustrated in FIGS. 4 and 5.

[0059] The at least one flow disruptor or at least one of the flow disruptors can also be embodied by scores 14 or furrows, or by a group of scores 14 running parallel to one another as in the exemplary embodiment illustrated in FIG. 6, that are arranged on the outer envelope, in particular the free section 10, of the shaft element 2. The shaft element 2 is thus imparted with a surface roughness which causes gas bubbles in the lubricant flowing around it to be broken up.

[0060] Of course, crankshafts 1 in which the groove 13 and/or the furrows or scores 14 are arranged on other surface sections, for example on the inner surface 12 of the bore 7 or the pass-through opening 19, are also included in the inventive concept.

[0061] FIG. 7 shows a crankshaft 1 according to the invention in a sectional view, in which the bore 7 is visible.

[0062] FIG. 8 shows Detail A from FIG. 7. The bore 7 arranged in the end region 4 of the shaft element 2, the additional bore 16, and the outlet opening 21 enabling the inflow of lubricant into the conveying groove 5 can thereby be seen.

LIST OF REFERENCE NUMERALS

[0063] 1 Crankshaft

[0064] 2 Shaft element

[0065] 3 Crankpin

[0066] 4 End region

[0067] 5 Conveying groove

[0068] 6 Longitudinal axis

[0069] 7 Bore

[0070] 8 Outer envelope surface

[0071] 9 Mounting section

[0072] 10 Free section

[0073] 11 Base of the conveying groove

[0074] 12 Inner surface of the bore

[0075] 13 Groove

[0076] 14 Score

[0077] 15 Adhesive dot

[0078] 16 Additional bore

[0079] 17 Longitudinal axis of the bore

[0080] 18 Longitudinal axis of the additional bore

[0081] 19 Pass-through opening

[0082] 20 Transition element

[0083] 21 Outlet opening

[0084] 22 Base surface