Patent Publication Number: US-2020291934-A1

Title: Lubricant holder for a coolant compressor

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     Applicant claims priority under 35 U.S.C. §119 of European Application No. 19161910.5 filed on Mar. 11, 2019, the disclosure of which is incorporated by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a lubricant holder for vertical conveying of lubricant by a crankshaft of a coolant compressor, comprising a sleeve element having a clear cross-section delimited by an inner wall. The cross-section extends along a longitudinal axis of the sleeve element, from an upper end to a lower end of the sleeve element. 
     The lubricant holder furthermore comprises an inner element that has a mantle surface that extends along a longitudinal axis of the inner element, from a lower end to an upper end, and on which a spiral is arranged. The spiral projects away from the mantle surface and runs in spiral shape from the region of the lower end to the region of the upper end of the mantle surface and delimits a channel, at least in certain areas. 
     In an operating state of the lubricant holder: 
     the inner element is arranged within the clear cross-section of the sleeve element with its mantle surface, at least in certain areas, in such a manner that a gap is disposed between an outer surface of the spiral and the inner wall, 
     viewed in the direction from the lower end to the upper end of the sleeve element, the lower end of the mantle surface is disposed in front of its upper end, and 
     the inner element and the sleeve element can be rotated relative to one another about the longitudinal axis of the sleeve element and/or the longitudinal axis of the inner element. 
     2. Description of the Related Art 
     In the case of coolant compressors having a compressor housing that can be hermetically encapsulated, an electrical drive unit arranged in a housing interior of the compressor housing, comprising a rotor and a stator, a crankshaft connected with the rotor in torque-proof manner, as well as a piston/cylinder unit arranged in the housing interior, which comprises a piston movably mounted in a cylinder of the piston/cylinder unit, which piston can be driven by the crankshaft for compression of coolant, ensuring sufficient lubrication of all the moving components is of particular importance. For this purpose, lubricant that collects in a coolant sump that covers a bottom region of the compressor housing may be conveyed in the direction of the cylinder by way of the crankshaft. 
     For this purpose, a sleeve-shaped lubricant holder or one having a sleeve element is often provided; this holder is connected with the crankshaft in torque-proof manner and arranged coaxial to it, and projects into the lubricant sump with an end section. Lubricant that has penetrated out of the lubricant sump into a cylindrical holding section of the lubricant holder through an entry opening is forced into a paraboloid shape due to the rotation of the lubricant holder—which is brought about by the rotation of the crankshaft—wherein the paraboloid forms along an inner wall of the lubricant holder or of the sleeve element that delimits the holding section, and along an inner wall of the crankshaft—which is structured to be hollow or is provided with a bore. Such a lubricant holder is known from AT 15828 U1, for example. 
     A maximal rising height to which the lubricant contained in the holding section of the lubricant holder can be raised in this manner is achieved in the region of the clear inside diameter of the crankshaft or of the bore, and depends on the square of the speed of rotation of the lubricant holder as well as on the square of the clear inside radius of the crankshaft or of the lubricant holder. The lubricant can then exit from the crankshaft to locations to be lubricated, by way of the at least one exit bore. 
     In the case of a corresponding selection of the production parameters (for example clear inside diameter of the crankshaft, height of the exit bores) and process diameter (for example speed of rotation of the crankshaft, viscosity of the lubricant) it is therefore possible to convey the lubricant from the bottom of the compressor housing, using the lubricant holder, by way of the crankshaft of the compressor, to the contact locations of the main bearing of the crankshaft, the crankpin, and the connecting rod of the coolant compressor. 
     In practice, nowadays compressors having a variable speed of rotation are increasingly being used—in contrast to conventional compressors having a fixed speed of rotation, which merely have two states, namely speed of rotation zero and a working speed of rotation of typically 3000 min −1 . In the case of compressors having a variable speed of rotation, both high and low speeds of rotation—typically minimally 800 min −1 —are regularly achieved in practice, as a function of a demanded cooling output. In order to achieve sufficiently great conveying output even at low speeds of rotation, it is known from the state of the art that the cylindrical holding section is structured to be open at the bottom and that an inner element, also structured to be cylindrical, is arranged in the holding section, so that a gap occurs between a mantle surface of the inner element and the inner wall of the holding section. The inner element typically has a spiral-shaped spiral that runs from bottom to top on its mantle surface, which spiral can be configured as a ridge that projects away from the mantle surface, for example. This arrangement clearly promotes conveying of the lubricant, because the lubricant is therefore conveyed not only through the gap, but also through a channel formed or delimited by the spiral. 
     In the case of high speeds of rotation, however, this arrangement has a negative effect, in that then too much lubricant or oil is conveyed through the channel, so that oil gets into the gaseous coolant to an increased degree, in particular by way of the suction muffler. The oil is undesirable in the coolant circuit, however, because the heat transfer in the condenser and evaporator is restricted by the oil. 
     In the solution described, from the state of the art, the inner element is essentially fixed in place in such a manner—typically by means of being tied in with the stator—that it does not rotate along with the crankshaft. Tilting, so that longitudinal axes of the sleeve element and of the inner element are no longer parallel to one another, however, is possible. This tilting is restricted by means of having the spiral make contact on the inner wall of the sleeve element, which wall delimits the holding section or a clear cross-section. 
     An ever more important demand on coolant compressors is the most compact, space-saving design possible. This demand brings about the result that the lubricant holders of such compact compressors are getting shorter and shorter. The spirals of such lubricant holders also become shorter, accordingly. The latter, in turn, leads to the result, in the case of a disadvantageous incline of the spiral, that in the case of tilting of the inner element, only a slight surface or no surface is available for contact of the spiral against the inner wall of the upper and lower part of the sleeve element. This result and an overly great gap between spiral and sleeve element can therefore make the tilting become so great that jamming of inner element and sleeve element can occur. As the result of such jamming, the lubricant feed is interrupted, and this interruption can lead to damage and even to total failure of the coolant compressor. 
     SUMMARY OF THE INVENTION 
     It is therefore an object of the invention to make available a lubricant holder that avoids the disadvantages described above. In particular, jamming of inner element and sleeve element and/or overly great lubricant feed at high speeds of rotation is/are supposed to be prevented. 
     These and other objects are achieved according to the invention, by providing a lubricant holder for vertical conveying of lubricant by means of a crankshaft of a coolant compressor, comprising a sleeve element having a clear cross-section delimited by an inner wall, which cross-section extends along a longitudinal axis of the sleeve element, from an upper end to a lower end of the sleeve element, the lubricant holder furthermore comprising an inner element that has a mantle surface that extends along a longitudinal axis of the inner element, from a lower end to an upper end, and on which a spiral is arranged, which spiral projects away from the mantle surface and runs in spiral shape from the region of the lower end to the region of the upper end of the mantle surface and delimits a channel, at least in certain areas, wherein in an operating state of the lubricant holder: 
     the inner element is arranged within the clear cross-section of the sleeve element with its mantle surface, at least in certain areas, in such a manner that a gap is disposed between an outer surface of the spiral and the inner wall, 
     viewed in the direction from the lower end to the upper end of the sleeve element, the lower end of the mantle surface is disposed in front of its upper end, 
     the inner element and the sleeve element can be rotated relative to one another about the longitudinal axis of the sleeve element and/or the longitudinal axis of the inner element, and 
     in the region of the upper end of the mantle surface, at least one contact section is provided, which projects away radially beyond the mantle surface, and the progression of which deviates from the spiral-shaped progression of the spiral. 
     The spiral “projecting away” from the mantle surface should be understood to be “radially projecting outward.” In other words the spiral extends, at every point of its progression, along a direction that stands normal to the mantle surface or to the longitudinal axis of the inner element, which direction faces away from the longitudinal axis. 
     The spiral-shaped progression of the spiral can be provided with a constant incline or a varying incline. 
     In particular, the spiral can run from the lower end to the upper end of the mantle surface. 
     The channel or a channel cross-section is delimited by the spiral, at least in certain areas, on two sides that lie opposite one another, and on a side of the mantle surface that is disposed between these sides, wherein the channel does not have a delimitation surface on the side that lies opposite the mantle surface, but rather is open. In other words the channel or the channel cross-section is closed only on three of four sides, and the mantle surface forms a bottom of the channel. 
     According to what has been stated above, the sleeve element and the inner element are designed in such a manner that in the operating state, the inner element is disposed, at least in certain areas, with its mantle surface, in the clear cross-section of the sleeve element, in such a manner that a gap is arranged between an outer surface of the spiral and the inner wall. 
     It should be noted that the mantle surface typically corresponds to the mantle of a rotating cylinder. Other shapes, however, for example shapes that narrow along the longitudinal axis of the inner element, in particular conical shapes, are also conceivable. The clear cross-section of the sleeve element is accordingly coordinated with the shape of the inner element or of the mantle surface, and typically has a cylindrical shape. Analogous to the mantle surface, other shapes, for example shapes that narrow along the longitudinal axis of the sleeve element, in particular conical shapes of the clear cross-section are also conceivable. 
     According to what has been stated above, the sleeve element and the inner element are designed in such a manner that in the operating state, viewed in the direction from the lower end to the upper end of the sleeve element, the lower end of the mantle surface is arranged in front of its upper end. In other words the sleeve element and the inner element are oriented in at least approximately the same manner. In practice, in the case of use in a coolant compressor that is in operation, in this connection the result occurs that the lower ends of the sleeve element and of the mantle surface are arranged below the upper ends of the sleeve element and of the mantle surface in the vertical direction. 
     Because only the relative rotation of the sleeve element and of the inner element relative to one another is important, the inner element, for example, can be connected with the crankshaft in torque-proof manner, and the sleeve element can be fixed in place rotationally—with the exception of angles of twisting that are slight enough to be ignored. During operation of the compressor, the crankshaft turns, and accordingly the inner element also turns, whereas the sleeve element does not rotate. 
     Alternatively, the sleeve element can be connected with the crankshaft in torque-proof manner, and the inner element can be rotationally fixed in place—with the exception of angles of twisting that are slight enough to be ignored. 
     A torque-proof connection between the inner element or sleeve element and the crankshaft can fundamentally take place directly or indirectly, i.e. with the intermediary of at least one further element such as a gasket, a fastening element, etc., for example. 
     In particular, the sleeve element can be connected with the crankshaft in the region of its upper end. It would be conceivable, for example, that the sleeve element with its clear cross-section in the region of the upper end is pushed onto the crankshaft and held on the latter by a press fit, for example. For this purpose, it can be provided that the clear cross-section in the region of the press fit is configured differently than in the region in which the inner element is arranged, at least in certain areas, in the operating state. 
     For the sake of good order, it should be stated that it is not excluded that the sleeve element for its part is a part or section of a larger element. The clear cross-section, however, extends over this part or section, in any case, i.e. over the sleeve element. 
     According to what has been stated above, the sleeve element and the inner element are designed in such a manner that in the operating state, the inner element and the sleeve element can be rotated relative to one another about the longitudinal axis of the sleeve element and/or about the longitudinal axis of the inner element. Accordingly, lubricant can enter into the gap—and thereby, at least as a further consequence, also into the channel—from a lubricant sump of the coolant compressor when the sleeve element and preferably also the inner element project into the lubricant sump, at least in certain areas. 
     The lubricant can be, in particular, an oil that is common for use in coolant compressors. 
     Relative rotation of the sleeve element and of the inner element relative to one another is brought about by means of rotation of the crankshaft, in particular in the case of a torque-proof connection of the sleeve element with the crankshaft. Preferably, in this regard the inner element does not rotate relative to the stator or rotates about only a restricted angle range, whereas the sleeve element rotates completely. As has already been stated above, however, a reverse design is also possible, in which the inner element rotates completely, and the sleeve element does not rotate relative to the stator or rotates about only a restricted angle range. 
     Due to the viscosity of the lubricant, i.e. the friction between lubricant and sleeve element or inner element, the lubricant is put into rotation, and therefore a corresponding centrifugal force acts on the lubricant. This force presses the lubricant in the gap and—due to the spiral that is present—in the channel, above all, in the direction of the crankshaft. 
     In operation, tilting of the inner element relative to the sleeve element can come about. In the case of conventional lubricant holders, a tilt angle that occurs between the longitudinal axis of the sleeve element and the longitudinal axis of the inner element during tilting is restricted by contact of the outer surface of the spiral against the inner wall of the sleeve element. 
     In the event of tilting, the contact section can make contact with the inner wall and thereby restrict the tilt angle in such a manner that jamming does not occur, in that the at least one contact section projects beyond the mantle surface radially, i.e. in directions standing perpendicular on the longitudinal axis or mantle surface and pointing away from it. In this regard, the at least one contact section can be designed to project so far away that only the contact section makes contact with the inner wall, not the outer surface of the spiral. 
     In this regard, the deviation of the progression of the at least one contact section from the progression of the spiral makes it possible that on the one hand, the placement of the at least one contact section can be restricted to the region of the upper end of the mantle surface, and on the other hand, at the same time, a sufficiently large angle range around the longitudinal axis of the inner element is covered by at least one contact section, so as to guarantee reliable contact against the inner wall if tilting occurs. 
     In this regard, the at least one contact section does not necessarily have to project away from the mantle surface itself, but rather, viewed along the longitudinal axis, for example, a distance between the mantle surface and the contact section can also be present. 
     Of course, multiple—for example two, three or more—contact sections can also be provided in the region of the upper end of the mantle surface. In particular, therefore, a contact section that is continuous or runs without interruption does not have to be provided, but rather multiple contact sections, for example along a circular line (in particular if the line lies in a plane that stands normal to the longitudinal axis of the inner element) or an elliptical line (in particular if the line lies in a plane that does not stand normal to the longitudinal axis of the inner element) can run around the longitudinal axis of the inner element. 
     By means of the placement of at least one contact section in the region of the upper end of the mantle surface, it is also ensured that the at least one contact section does not hinder entry of the lubricant into the channel. The latter is important for reliable lubrication, in particular in the case of low speeds of rotation, wherein in this regard, the lubricant typically does not fill the channel or the channel cross-section completely when it is being conveyed in the direction of the crankshaft. 
     At the same time, however, the result can be achieved, by means of the restriction of the channel or of the channel cross-section by means of the at least one contact section in the region of the upper end of the mantle surface, that at high speeds of rotation, restriction of the lubricant flow takes place. In this case, specifically, the channel is usually completely filled with lubricant, and by means of the restriction of the channel in certain areas, by means of the at least one contact section—in addition to the restriction by the spiral—narrowing of the channel can be achieved. This narrowing in turn brings about backing up of the lubricant, and thereby a restriction of lubricant conveying at high speeds of rotation. 
     Accordingly, it is provided, in the case of a preferred embodiment of the lubricant holder according to the invention, that the channel has a reduced channel cross-section in the region of the at least one contact section. In other words, the channel cross-section is reduced in comparison with at least one section of the channel outside of this region. Preferably, the channel cross-section is reduced in the region of the contact section in comparison with outside of this region; in other words, all the sections of the channel that lie outside of this region have a larger channel cross-section. The reduced channel cross-section is achieved, in this regard, in that the at least one contact section restricts the channel at least in certain areas. 
     In order to achieve an essentially incline-free progression of the at least one contact section in contrast to the progression of the spiral, which progression has an incline, it is provided, in a preferred embodiment of the lubricant holder according to the invention, that the at least one contact section, viewed along the longitudinal axis of the inner element, is delimited by a first boundary surface and a second boundary surface, which are arranged one behind the other, and that the first boundary surface, the second boundary surface, or both stand normal to the longitudinal axis of the inner element. As a result, the throttle effect on lubricant conveying can be increased at high speeds of rotation. Furthermore, such a design of the at least one contact section proves to be advantageous in terms of production technology. 
     In the case of a preferred embodiment of the lubricant holder according to the invention, it is provided that the spiral directly follows the at least one contact section. As a result, advantageous flow conditions for the lubricant can be ensured in the region of the at least one contact section. Furthermore, such a configuration also proves to be advantageous in terms of production technology. 
     As previously mentioned, the result can be achieved, by means of the progression of the at least one contact section, that a sufficiently large angle range about the longitudinal axis of the inner element is covered by at least one contact section, so as to guarantee reliable contact against the inner wall if tilting occurs. Accordingly, it is provided, in a preferred embodiment of the lubricant holder according to the invention, that the at least one contact section covers an angle range around the longitudinal axis of the inner element, which range amounts to at least 15°, preferably at least 45°, particularly preferably at least 90°. 
     Thus it would be conceivable, for example, to provide a continuous contact section that covers a specific angle range—for example of 60°—or three contact sections, each of which covers a part of the specific angle range—for example 20° each in the said example—wherein the contact sections are arranged in such a manner that they do not overlap and thereby cover the specific angle range in total. 
     By skillful placement of the contact sections, a relatively small covered angle range can already be sufficient for stable running. In practice, achieving stable running often presents itself as an optimization problem, in which the desired stability, the clear channel cross-section, the speed of rotation of the crankshaft, the oil viscosity, the progression of the spiral, and the friction between the at least one contact section and the inner wall of the sleeve element must be taken into consideration. For example, use situations are conceivable, in which four contact sections are provided for stable running, each covering an angle range of only 5°, so that the contact sections in total cover an angle range around the longitudinal axis of the inner element that amounts to 20°. 
     In the case of a particularly preferred embodiment of the lubricant holder according to the invention, it is provided that the angle range amounts to 360°. In other words the entire angle range around the longitudinal axis of the inner element is covered by the at least one contact section. 
     Theoretically, it would be conceivable that multiple contact sections are provided for this purpose, which are arranged one behind the other at least in certain areas, viewed along the longitudinal axis of the inner element. For example, it would be conceivable to provide three contact sections, which each cover 120° and are arranged not to overlap, in such a manner that they cover the entire angle range of 360° in total. It would also be conceivable, however, to provide three contact sections that each cover more than 120° and are arranged to overlap, in such a manner that they cover the entire angle range of 360° in total. 
     In the case of a particularly preferred embodiment of the lubricant holder according to the invention, it is provided that the at least one contact section comprises at least one closed contact section, wherein each closed contact section covers the entire angle range, in each instance. In other words, theoretically one or more closed contact sections can be provided, wherein in the case of multiple closed contact sections, these sections are arranged one behind the other, viewed along the longitudinal axis of the inner element. As a result, optimally reliable restriction of the tilt angle can be achieved, and thereby optimal protection against jamming can be achieved. 
     For reasons of production technology or economics, in particular, it is provided, in the case of a preferred embodiment of the lubricant holder according to the invention, that precisely one contact section is provided. If, in this case, the contact section is configured as a closed contact section, in particular, a particularly good compromise can be achieved between simplicity in terms of production technology and reliable restriction of the tilt angle. 
     In the case of a preferred embodiment of the lubricant holder according to the invention, it is provided that the inner element has a cavity that is open, viewed in the direction toward the upper end of the mantle surface, along the longitudinal axis of the inner element. This arrangement allows a simple, material-saving, and cost-advantageous method of production, among other things. 
     In the case of a particularly preferred embodiment of the lubricant holder according to the invention, it is provided that at least one passage opening is provided in the region of the upper end of the mantle surface, wherein the at least one passage opening connects the channel with the cavity. 
     In other words, the at least one through-flow opening creates a fluidic connection between the channel and the cavity. Accordingly, the lubricant can get from the channel into the cavity through the at least one passage opening and from there—because the cavity is open upward, i.e. in the direction toward the upper end of the mantle surface—into the clear cross-section of the sleeve element or to the crankshaft. This arrangement is advantageous for improved lubricant conveying. 
     If a closed contact section is provided, which delimits the channel at least in certain areas, the at least one passage opening can also prove to be necessary in interplay with the cavity, so as to allow sufficient conveying of the lubricant out of the channel in the direction of the crankshaft. 
     If the channel is completely closed off in the direction of the upper end of the mantle surface by means of the closed contact section, in particular, the lubricant could be transported further in the direction of the crankshaft only by way of the gap if there is no passage opening, and under some circumstances, which are dependent on the speed of rotation and the gap width, among other things, this arrangement would result in insufficient conveying of lubricant. 
     Analogous to what has been stated above, it is provided, according to the invention, in the case of a coolant compressor having a compressor housing that can be hermetically encapsulated, an electrical drive unit arranged in a housing interior of the compressor housing, comprising a rotor and a stator, a crankshaft connected with the rotor in torque-proof manner, as well as a piston/cylinder unit arranged in the housing interior, which comprises a piston movably mounted in a cylinder of the piston/cylinder unit, which piston can be driven by the crankshaft for compression of coolant, that the coolant compressor has a lubricant holder according to the invention that is in the operating state, so as to convey lubricant out of a lubricant sump formed in a bottom region of the compressor housing, by way of the crankshaft, wherein the crankshaft has a bore that runs at a slant to an axis of rotation of the crankshaft, preferably at least in certain areas, and/or at least one groove that stands in a fluidic connection with the clear cross-section of the sleeve element. 
     For the sake of good order, it should be noted that the lubricant holder according to the invention can, of course, also be used in compressors in which the crankshaft has no bore, but rather has at least one groove, for example, for further conveying the lubricant, which groove stands in a fluidic connection with the clear cross-section of the sleeve element. 
     As has also been explained above, the inner element or the sleeve element can be connected with the crankshaft in torque-proof manner. Accordingly, it is provided, in the case of a preferred embodiment of the coolant compressor according to the invention, that the sleeve element of the lubricant holder is connected with the crankshaft in torque-proof manner. 
     Accordingly, the inner element can be connected, in essentially torque-proof manner, with the stator or other components of the coolant compressor, relative to which the crankshaft rotates. 
     Accordingly, the inner element can have a fastening element, preferably in the region of the lower end of the mantle surface, which fastening element can interact with a fixation means, so as to produce the said torque-proof connection. For example, the fastening element can be an eye. The fixation means can be a bracket, for example, which can be brought into engagement with the eye. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other objects and features of the invention will become apparent from the following detailed description considered in connection with the accompanying drawings. It is to be understood, however, that the drawings are designed as an illustration only and not as a definition of the limits of the invention. 
       In the drawings, 
         FIG. 1 a    shows an inner element of an embodiment of a lubricant holder according to the invention, in a side view; 
         FIG. 1 b    shows the inner element from  FIG. 1 a    in a front view; 
         FIG. 1 c    shows the inner element from  FIG. 1 a    in a sectional view according to the section line I-I in  FIG. 1   a;    
         FIG. 2 a    shows an inner element of a further embodiment of the lubricant holder according to the invention, in a side view; 
         FIG. 2 b    shows the inner element from  FIG. 2 a    in a front view; 
         FIG. 2 c    shows the inner element from  FIG. 2 a    in a sectional view according to the section line II-II in  FIG. 2   b;    
         FIG. 3  shows a sectional view of the embodiment of the lubricant holder according to the invention, with the inner element from  FIG. 1 a    or  FIG. 1 c   , wherein the lubricant holder is mounted on a crankshaft of a coolant compressor according to the invention; and 
         FIG. 4  shows a sectional view of a coolant compressor according to the invention, with the lubricant holder from  FIG. 3 . 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       FIG. 1 a    shows a side view of an inner element  9  of an embodiment of a lubricant holder  1  according to the invention. Lubricant holder  1  is shown in  FIG. 3  in a sectional view, in an operating state and fastened to a crankshaft  2  of a coolant compressor  3  according to the invention. 
     The lubricant holder  1  serves for vertical conveying of lubricant, in particular oil  15 , from a lubricant sump  26  formed in a bottom region  25  of a compressor housing  18  of the coolant compressor  3 , see also the sectional view of  FIG. 4 , by way of the crankshaft  2 . For this purpose, the crankshaft  2  has a bore  27  that can be seen well in  FIG. 3 , from which bore the oil  15  can exit to locations to be lubricated, by way of exit bores  28 . For optimal conveying of the oil  15 , the bore  27  can be structured to run at a slant to an axis of rotation  29  of the crankshaft  2 . 
     Furthermore, an electrical drive unit  19  having a rotor  20  and a stator  21  is arranged in the compressor housing  18 , wherein the crankshaft  2  is connected with the rotor  20  in torque-proof manner. Furthermore, a piston/cylinder unit  22  is situated in the compressor housing  18 , which unit comprises a piston  23  mounted so as to move in the cylinder  24  of the piston/cylinder unit  22 , which piston can be driven by the crankshaft  2  for compression of coolant. 
     The lubricant holder  1  comprises a sleeve element  4  having a clear cross-section  5  delimited by an inner wall  33 , which cross-section extends along a longitudinal axis  6  of the sleeve element  4 , from an upper end  7  to a lower end  8  of the sleeve element  4 . As can be seen in  FIG. 3 , the clear cross-section  5  can serve to hold the crankshaft  2  at the upper end  7 , for example so as to produce a torque-proof connection between the sleeve element  4  and thereby the lubricant holder  1  and the crankshaft  2 , for example by means of a press fit. 
     Furthermore, the lubricant holder  1  comprises the inner element  9 , which has a mantle surface  10  that extends along a longitudinal axis  11  of the inner element  9 , from a lower end  12  to an upper end  13 . A spiral  14  is arranged on the mantle surface  10 , which spiral projects radially outward from the mantle surface  10  and runs in spiral shape from the region of the lower end  12  to the region of the upper end  13  of the mantle surface  10 —from the lower end  12  to the upper end  13  of the mantle surface  10  in the exemplary embodiment shown. 
     For reasons of production technology, the spiral  14  can have short interruptions, which can be seen in  FIG. 1 a    and  FIG. 2 a   . A channel  32  having a channel cross-section  42  is formed or delimited by the spiral  14  and the mantle surface  10 . In this regard, the channel  32  or a channel cross-section  42  is delimited, at least in certain areas, on two sides that lie opposite one another, by the spiral  14 , and by the mantle surface  10  on a side arranged between these sides, wherein the channel  32  has no delimitation surface on the side that lies opposite the mantle surface  10 , but rather is open. 
     In other words, the channel  32  or the channel cross-section  42  is closed on only three of four sides, and the mantle surface  10  forms a bottom of the channel  32 . 
     In the operating state of the lubricant holder  1 , the inner element  9  is arranged, with its mantle surface  10 , at least in certain areas—in the exemplary embodiment shown, essentially completely—within the clear cross-section  5  of the sleeve element  4 . In this regard, viewed in the direction from the lower end  8  to the upper end  7  of the sleeve element  4 , the lower end  12  of the mantle surface  10  is arranged in front of its upper end  13 , in other words the sleeve element  4  and the inner element  9  are oriented or aligned in the same way, as it were. 
     In the exemplary embodiments shown, the mantle surface  10  corresponds to the mantle of a rotating cylinder. The clear cross-section  5  of the sleeve element  4  is accordingly coordinated with the shape of the inner element  9  or the mantle surface  10 , and has a corresponding cylinder shape in the region in which the inner element  9  is held in the sleeve element  4  or arranged in the clear cross-section  5  in the operating state. 
     The sleeve element  4  and the inner element  9  are furthermore designed in such a manner that the inner element  9  and the sleeve element  4  can be rotated relative to one another about the longitudinal axis  6  of the sleeve element  4  and/or the longitudinal axis  11  of the inner element  9 . This rotation is imparted or generated during operation of the coolant compressor  3  by means of the torque-proof connection of the lubricant holder  1  with the crankshaft  2 . Fundamentally, the only important thing is the relative rotation between the sleeve element  4  and the inner element  9 . In other words, it would also be conceivable that the inner element  9  is driven rotationally and the sleeve element  4  is essentially fixed in place rotationally. In the exemplary embodiment shown, the sleeve element  4  is driven rotationally when the crankshaft  2  turns, while the inner element  9  is not driven, due to the torque-proof connection of the sleeve element  4  with the crankshaft  2 . 
     In order to prevent rotational movements of the inner element  9  to the greatest possible extent, this element can be connected with the stator  21 , for example, by means of a fixation means. For this purpose, the inner element  9  can have a fastening element in the form of an eye  16 , for example, as can be seen well in the front view of  FIG. 1 b   , with which eye the fixation means can be brought into engagement. In the exemplary embodiment shown in  FIG. 4 , a bracket  31  is provided as the fixation means, which bracket stands in engagement with the eye  16  and produces the connection of the inner element  9  with the stator  21 . 
     As is evident from  FIG. 3 , for example, in the operating state the inner element  9  is arranged within the clear cross-section  5  of the sleeve element  4  in such a manner that a gap  30  having a gap width is arranged between an outer surface  34  of the spiral  14 , which outer surface  34  delimits the spiral  14  radially toward the outside, and the inner wall  33 . The gap  30  guarantees problem-free relative rotation of inner element  9  and sleeve element  4  relative to one another. 
     Accordingly, the oil  15  from the lubricant sump  26  can enter into this gap  30 , as well as into the channel  32 , when the inner element  9  and the sleeve element  4  project into the lubricant sump  26  at least in certain areas. In this regard, the sleeve element  4  projects into the lubricant sump  26 , in particular in the region of its lower end  8 , and the inner element  9  projects into it in particular in the region of the lower end  12  of its mantle surface  10 . Due to the viscosity of the oil  15  or the friction between oil  15  and sleeve element  4 , a corresponding centrifugal force acts on the oil  15  during rotation of the sleeve element  4 . This force presses the oil  15  in the gap  30  and, in particular, in the channel  32  in the direction from the lower end  12  to the upper end  13  of the mantle surface  10 , and thereby in the direction of the crankshaft  2 . 
     In each case, the oil  15  can flow particularly well in the direction of the crankshaft  2  by way of the channel  32 —independent of the precise gap width. In the exemplary embodiment shown, the bore  27  of the crankshaft  2  stands in a fluidic connection with the clear cross-section  5  and thereby ultimately also with the channel  32 , so that the oil  15  can get all the way into the bore  27 . 
     In operation, tilting of the inner element  9  relative to the sleeve element  4  can occur, so that a tilt angle occurs between the longitudinal axis  6  of the sleeve element  4  and the longitudinal axis  11  of the inner element  9 . In order to limit the tilt angle and thereby to prevent jamming of the inner element  9  in the sleeve element  4  or in the clear cross-section  5 , according to the invention at least one contact section  35  is provided in the region of the upper end  13  of the mantle surface  10 , which section projects radially beyond the mantle surface  10 , and the progression of which deviates from the spiral-shaped progression of the spiral  14 . In that the at least one contact section  35  projects beyond the mantle surface  10  radially, i.e. in directions standing perpendicular to the longitudinal axis  11  or mantle surface  10 , the contact section  35  can make contact with the inner wall  33  in the event of tilting, and thereby limit the tilt angle in such a manner that no jamming comes about. 
     The deviation of the progression of the at least one contact section  35  from the progression of the spiral  14  makes it possible, in this regard, that on the one hand, the placement of the at least one contact section  35  can remain concentrated in the region of the upper end  13  of the mantle surface  10 , and on the other hand, at the same time a sufficiently great angle range  36  around the longitudinal axis  11  of the inner element  9  is covered by at least one contact section  35 , so as to guarantee reliable contact against the inner wall  33  in the event that tilting occurs. 
     Of course, multiple contact sections  35 —for example two, three or more—can also be provided in the region of the upper end  13  of the mantle surface  10 . The inner element  9  of  FIG. 1 a    has two contact sections  35 , for example, as can be seen well in comparison with  FIG. 1 b   . In  FIG. 1 a   , it can be seen that the spiral  14  directly follows one of the contact sections  35 , wherein the transition to this contact section  35  is indicated by a dotted line. This contact section  35  encloses an angle range  36  of approximately 100°. The other one of the two contact sections  35  is arranged on the opposite side of the mantle surface  10 . In other words, the two contact sections are arranged along a circular line around the longitudinal axis  11 , wherein the circular line lies in a plane that stands normal to the longitudinal axis  11 . The other one of the two contact sections also covers an angle range of approximately 100°, so that in total, approximately 200° are covered by the two contact sections  35 . The likelihood that in the event of tilting of the inner element  9 , contact of one of the contact sections  35  against the inner wall  33  will come about, and that the tilt angle will be effectively limited, is correspondingly great. 
     Furthermore, it is also ensured by means of the placement of the at least one contact section  35  in the region of the upper end  13  of the mantle surface  10  that the at least one contact section  35  will not hinder entry of the oil  15  into the channel  32 . The latter is important for reliable lubrication, in particular at low speeds of rotation, wherein the oil  15  typically does not completely fill the channel  32  or the channel cross-section  42  in this regard, when it is being conveyed in the direction of the crankshaft  2 . 
     At the same time, the at least one contact section  35  delimits the channel  32  or the channel cross-section  42  in the region of the upper end  13  of the mantle surface  10 . In  FIGS. 1 a  and 1 b    as well as in the sectional view of  FIG. 1 c   , it can be seen well that because of the contact sections  35 , the channel cross-section  42  in the region of the upper end  13  of the mantle surface  10  or in the region of the contact sections  35  is clearly smaller than in a region between the upper end  13  and the lower end  12  or than in the region of the lower end  12  of the mantle surface  10 . The reduced channel cross-section  42  in the region of the contact sections  35  that is achieved in this way brings about a restriction of the lubricant flow at high speeds of rotation. This result occurs because in the event of high speeds of rotation, the channel  32  is usually filled completely by the oil  15 . Because of the restriction of the channel  32  in certain areas by means of the at least one contact section  35 , a constriction of the channel  32  is created, which then brings about backing up of the oil  15  and thereby restriction of lubricant conveying at high speeds of rotation. 
     In contrast to the progression of the spiral  14 , which has an incline, the contact sections  35  in the exemplary embodiment of  FIGS. 1 a , 1 b , 1 c    have an essentially incline-free progression, so that the reduction in the channel cross-section  42  as described is achieved. In this regard, the contact sections  35  are configured in such a manner that they are delimited, in each instance, by a first boundary surface  40  and a second boundary surface  41 , which are arranged one behind the other, viewed along the longitudinal axis  11  of the inner element  9 , wherein the second boundary surface  41  stands normal to the longitudinal axis  11  of the inner element  9 . 
     As is evident from  FIG. 1 c   , the inner element  9  of the embodiment shown has a cavity  38 , which is open in the direction toward the upper end  13  of the mantle surface  10 . In this way, cost-advantageous and simple production is made possible. 
       FIGS. 2 a , 2 b , 2 c    relate to an inner element  9  of a further embodiment of the lubricant holder  1  according to the invention. This inner element also has the cavity  38 , which is open in the direction toward the upper end  13  of the mantle surface  10 . In this exemplary embodiment, only one contact section  35  is provided, which is configured as a closed contact section  37 . This closed contact section  37  covers the entire angle range  36  of 360°, and, in the exemplary embodiment shown, runs on a circular line that lies in a plane that stands normal to the longitudinal axis  11 . Extremely great certainty of preventing undesirable jamming in the event of tilting in all directions can thereby be guaranteed. 
     In this case, too, the spiral  14  follows the contact section  35  directly, as is indicated with the dotted line in  FIG. 2 a    and  FIG. 2 b   , in each instance. Accordingly, the channel cross-section  42  narrows to zero. In order to nevertheless be able to convey oil  15  from the channel  32  further to the crankshaft  2 , it is true that in principle, the gap  30  is available, but the amount conveyed per time is thereby restricted. Furthermore, back-flow through the gap  30  must be expected. For this reason, in this exemplary embodiment two passage openings  39  are provided, which are arranged to lie opposite one another in the region of the upper end  13  of the mantle surface  10 , and fluidically connect the channel  32  with the cavity  38 . In other words, the oil  15  can get from the channel  32  into the cavity  38  through the passage openings  39 , and from there—since this cavity is open toward the top, i.e. in the direction toward the upper end  13  of the mantle surface  10 —into the clear cross-section  5  of the sleeve element  4  or to the crankshaft  2 . This arrangement is advantageous for improved lubricant conveying. 
     For the remainder, what has been stated above in connection with the exemplary embodiment of  FIGS. 1 a , 1 b , 1 c    also holds true for the exemplary embodiment of  FIGS. 2 a , 2 b   ,  2   c.    
     Although only a few embodiments of the present invention have been shown and described, it is to be understood that many changes and modifications may be made thereunto without departing from the spirit and scope of the invention.