Shaft seal for a refrigerant compressor

In order to improve a compressor for refrigerant, comprising a housing, at least one refrigerant-compressing element arranged in the housing, a shaft which has a section extending in the housing and driving the refrigerant-compressing element, a section passing through a wall of the housing and a drive section projecting out of the housing as well as a sealing arrangement effective between the section of the shaft passing through the wall and the housing and having a slide ring seal and an outer sealing ring, between which an oil receiving chamber is arranged, from which oil can be discharged via an oil outlet, in such a manner that, on the one hand, as little oil as possible leaks out and, on the other hand, as good a shut-off as possible in relation to the entry of air can be achieved it is suggested that an oil collecting area of the oil receiving chamber communicate via a siphon arrangement with an ascending channel which leads to an outlet for the oil.

The invention relates to a compressor for refrigerant, comprising a
 housing, at least one refrigerant-compressing element arranged in the
 housing, a shaft which has a section extending in the housing and driving
 the refrigerant-compressing element, a section passing through a wall of
 the housing and a drive section projecting out of the housing as well as a
 sealing arrangement effective between the section of the shaft passing
 through the wall and the housing, the sealing arrangement having a slide
 ring seal and an outer sealing ring, between which an oil receiving
 chamber is arranged, from which oil can be discharged via an oil outlet.
 Compressors of this type are known from the state of the art. For example,
 it is provided for the oil to issue from the oil receiving chamber via an
 oil outlet, wherein the oil outlet is a channel leading to the outside
 directly from the oil receiving chamber.
 Such a solution has the disadvantage that, on the one hand, appreciable
 amounts of oil can leak out and their collection must be taken care of and
 that, on the other hand, it is possible for air to enter the oil receiving
 chamber and also, via this, the interior of the compressor and cause
 corrosion.
 SUMMARY OF THE INVENTION
 The object underlying the invention is therefore to improve a compressor of
 the generic type in such a manner that, on the one hand, as little oil as
 possible leaks out and, on the other hand, as good a shut-off as possible
 in relation to the entry of air can be achieved.
 This object is accomplished in accordance with the invention, in a
 compressor of the type described at the outset, in that an oil collecting
 area of the oil receiving chamber communicates via a siphon arrangement
 with an ascending channel which leads to an outlet for the oil.
 The advantage of the inventive solution is to be seen in the fact that, on
 the one hand, air is prevented from entering to a great extent by the
 siphon arrangement and, on the other hand, the ascending channel following
 the siphon arrangement contributes to retaining the oil to as great an
 extent as possible in the oil collecting area and thus of allowing as
 little oil as possible to leak out when it is assumed that the ascending
 channel and the oil receiving chamber are filled via the siphon
 arrangement in accordance with the principle of communicating pipes.
 In this respect, it is particularly expedient when the ascending channel is
 designed as an oil storage means. In this case, the ascending channel
 serves, in addition, to store oil passing through the siphon arrangement
 prior to exiting and thus creates the possibility, in addition, of
 retaining oil to a considerable extent and, where possible, not allowing
 it to leak out and, in particular, in the cases where an underpressure
 occurs in the interior of the compressor of seeing to it that the stored
 oil flows back into it again.
 With respect to the design of the ascending channel, the most varied of
 possibilities are conceivable.
 For example, it would be conceivable to design the ascending channel by way
 of a pipe introduced into the oil receiving chamber.
 It is, however, particularly expedient when the ascending channel extends
 along a housing wall and thus requires as little space as possible so that
 no additional constructional space need be made available for the
 inventive solution.
 A solution, with which the ascending channel extends in the housing wall,
 saves even more on space.
 In order to give the ascending channel as large a volume as possible
 without this requiring a large cross section it is preferably provided for
 the ascending channel to be designed as an annular channel which surrounds
 the shaft and is thus, on the one hand, easy to arrange and, on the other
 hand, has a very large volume for storing oil on account of the annular
 encircling of the shaft.
 For reasons of functional efficiency it is particularly favorable when the
 ascending channel is formed by two interacting elements which limit the
 ascending channel and so these elements merely need to be fitted together
 during the manufacture of the inventive compressor.
 A particularly favorable solution provides for one of the elements to be a
 section of the housing wall and the other to be an insert member abutting
 on the section so that a further simplification of production results due
 to the fact that one of the elements can already be formed by a section of
 the housing wall and thus no separate part is required.
 The ascending channel can be formed by the two elements particularly
 inexpensively when one of the elements has a groove. In this respect, it
 could, in principle, also be conceivable for the other element of the
 elements to have a groove and for both grooves together to form the
 ascending channel.
 It is, however, even simpler when the other one of the elements covers the
 groove.
 With respect to the position of the ascending channel itself, no further
 details have been given. It would, for example, be conceivable to form the
 ascending channel outside the housing preferably on parts to be arranged
 on it. It is, however, particularly advantageous when the ascending
 channel is located within an outer contour of the housing.
 It is even more advantageous, in order not to alter the outer contour of
 the housing at all, when the elements interacting to form the ascending
 channel are both located within an outer contour of the housing.
 A particularly favorable solution provides for one of the elements to be
 formed by the outer seal of the compressor so that, for this as well, no
 additional part need be mounted on the compressor but the seal which is
 present in any case can be used for limiting the ascending channel.
 With respect to the design of the siphon arrangement, no further details
 have been given in conjunction with the preceding description of the
 individual embodiments. One advantageous solution, for example, provides
 for the siphon arrangement to comprise an oil bath shutting off an inlet
 of the ascending channel.
 This oil bath is preferably formed in a recess located in front of the
 inlet into the ascending channel.
 This recess is preferably provided in the housing wall in order not to have
 to use any additional components and thus to have a solution available
 which is inexpensive and as simple as possible to produce with parts which
 are present in any case.
 In the simplest case, the recess is arranged such that it adjoins the
 groove forming the ascending channel and overlaps with it, wherein the
 inlet for the ascending channel is also formed by the overlapping.
 With respect to the continuation of the ascending channel, no further
 details have been given in conjunction with the inventive solution
 described thus far. One advantageous embodiment, for example, provides for
 the ascending channel to open into an outlet channel leading to the
 outlet. As a result, the ascending channel does not lead directly out of
 the housing but this is ensured by an additional outlet channel and so the
 ascending channel can be arranged at the most favorable location
 irrespective of the position of the outlet.
 In this respect, the outlet channel is preferably designed such that it
 passes through the housing, in particular, a housing wall thereof.
 In order to prevent, in addition, any dirt penetrating the outlet channel,
 the outlet is closed by a member permeable to oil which is produced, in
 particular, from a porous material, such as, for example, felted or
 sintered metal or the like.
 In order to counteract as comprehensively as possible any exiting of
 leakage oil based on the principle of communicating pipes, it is
 preferably provided for the outlet to be arranged on a side of the shaft
 located opposite the oil collecting area, preferably at a point of the
 housing located as high as possible, at least at the level of a maximum
 height of the oil receiving chamber and thus a considerable degree of
 filling of the oil receiving chamber is required in order to allow oil, in
 particular, leakage oil to issue from the outlet.
 Additional features and advantages of the invention are the subject matter
 of the following description as well as the drawings illustrating several
 embodiments.

DETAILED DESCRIPTION OF THE INVENTION
 One embodiment of an inventive compressor illustrated in FIG. 1 comprises a
 housing designated as a whole as 10, in which pistons 12 are movable in
 cylinders provided for them as refrigerant-compressing elements.
 The pistons 12 are thereby driven by a shaft which is designated as a whole
 as 14, has a crankshaft section 16 and projects beyond one side of the
 housing 10 with a drive section 18. A section 20 of the shaft 14, which is
 sealed in relation to a cover plate 22 of the housing 10 by means of a
 sealing arrangement 24, is arranged between the crankshaft section 16 and
 the drive section 18.
 As illustrated in FIG. 2, the sealing arrangement 24 preferably arranged in
 the cover plate 22 comprises a slide ring seal which is designated as a
 whole as 26 and has a unit 28 co-rotating with the section 20 of the
 shaft, a unit 30 non-rotatably seated in the cover plate 22 as well as a
 slide ring 32 which is effective between the rotating unit 28 and the
 stationary unit 30 in order to seal a housing interior 34 against oil
 leaking outwards.
 Apart from the slide ring seal designated as 26, the sealing arrangement 24
 comprises, in addition, an outer sealing ring 36 which is arranged in an
 outer wall 38 of the cover plate 22 of the housing penetrated by the
 section 20 of the shaft 14, namely on a side of the slide ring seal 26
 facing away from the interior 34, and between the slide ring seal 26 and
 outer surroundings 40 of the housing 10 creates an additional seal between
 the housing 10 and the section 20 of the shaft 14 (FIG. 2).
 The outer seal 36 is designed, for example, as a lip seal and comprises an
 annular sealing member 44, proceeding from which a sealing lip 46 extends
 in the direction of the section 20 of the shaft 14 and in the direction of
 the slide ring seal 26 and thus abuts on the section 20 in a reinforced
 manner during any increase in pressure in an oil receiving chamber 42
 located between the slide ring seal 26 and the outer seal 36 and thus
 prevents any so-called "blow-through" through the outer seal 36.
 As illustrated on an enlarged scale in FIG. 3, the stationary unit 30 of
 the slide ring seal is seated in a step-like seat 50 which is arranged on
 an inner side of the outer wall 38 of the cover plate 22.
 Furthermore, an annular recess 52, which is open towards the outer side of
 the outer wall 38 and is of an annular and, in cross section, step-like
 design, is preferably provided for the outer seal 36, wherein the outer
 wall 38 has between the annular recess 52 and the step-like seat 50 on the
 outer wall 38 a flange 54 which points in the direction of the shaft 14
 and limits with an inner cylinder surface 56 the free space designated as
 oil receiving chamber 42 between the flange 54 and the section of the
 shaft 14.
 The oil receiving chamber 42 located between the stationary unit 30 of the
 slide ring seal 26 and the outer seal 36 and extending annularly around
 the section 20 of the shaft 14 forms at its lowest point facing an
 underside 58 of the housing an oil collecting area 60, in which the oil
 allowed through the slide ring seal 26, in particular, leakage oil is
 collected which has no chance to pass to the outside through the outer
 seal 36.
 In order to provide a drainage possibility for this leakage oil in the case
 where it occurs in greater amounts, a circular-cylindrical outer surface
 62 of the annular recess 52 is, as illustrated in FIG. 4, provided with a
 groove 64 which, as illustrated in FIG. 3, is closed by the annular
 sealing member 44 pressed into the annular recess 52 and thus forms a
 closed ascending channel 66 which surrounds the section 20 of the shaft 14
 annularly and opens into an outlet channel 68 which, for its part, passes
 through the wall 38 of the cover plate 22 of the housing 10 and opens into
 an outlet 70 which is arranged above a highest point of the oil receiving
 chamber 42, for example, in an outer casing surface of the cover plate 22.
 The outlet 70 is thereby of a broadened design in its cross section and
 accommodates, for its part, a closure element 74 permeable to oil, for
 example, a porous plug 74 designed, in particular, from a felt or sintered
 material.
 In order to give the oil collecting in the oil collecting area 60 the
 possibility of entering the ascending channel 66, a pocket 80 locally
 widening the annular recess 52 is, as illustrated in FIGS. 5 and 6, milled
 into the flange 54, this pocket extending in a recessed manner into the
 flange 54 and the housing wall 38 in a radial direction to the shaft 14 in
 relation to the inner cylinder surface 56 of the circular-cylindrical
 outer surface 62 and in an axial direction to the shaft proceeding from
 the groove 64 as far as beyond an annular flange surface 76 of the annular
 recess 52 so that, as illustrated in FIGS. 3 and 6, a passage 82 remains
 between the outer seal 36 and the flange 54 in the area of the pocket 80,
 the oil from the oil collecting area 60 being able to pass through this
 passage into a sink limited by side walls 86, 88 of the pocket 80 and
 there form an oil bath 90, from which the oil can pass into the groove 64
 and thus into the ascending channel 66 via an inlet opening 84 formed in
 an overlapping area between the pocket 80 and the groove 64.
 The passage 82 thereby forms with the oil bath 90 closing the inlet opening
 84 a siphon arrangement which forms an essentially gas-tight shut-off
 between the ascending channel 66 and the oil receiving chamber 42 even
 with oil exiting in small amounts and so no air and thus also no oxygen
 can penetrate into the oil receiving chamber 42 and thus from there
 through the slide ring seal 26 into the housing interior 34 of the
 compressor.
 The pocket 80 is preferably provided in the lowest lying area of the
 annular recess 52 facing the lower part 58 of the housing 10 and extends
 in a radial direction in relation to the shaft 14 as far as a base 92 of
 the groove 64 and in axial direction in relation to the shaft 14
 preferably proceeding from the groove 64 over a depth which is greater
 than a distance between the groove 64 and an annular flange surface 76 of
 the annular recess 52 which is formed by the flange 54.
 A sufficiently wide passage 82 for oil collecting in the oil collecting
 area 60 thus remains between an end wall 88 of the pocket 80 and the outer
 seal 36.
 The ascending channel 66 serves, in accordance with the invention, not only
 for allowing the oil entering it to ascend in the direction of the outlet
 channel 68 and, finally, the outlet 70 but also at the same time as an oil
 storage means for leakage oil from the oil collecting area 42 so that this
 can be stored prior to exiting from the outlet 70 in order to allow as
 little oil as possible to issue from the outlet 70.
 Furthermore, this oil storage means formed by the ascending channel 66 has
 the additional advantage that during any occurrence of underpressure in
 the interior 34 of the compressor, which has an effect on the oil
 receiving chamber 43 through the slide ring seal 26, the oil bath 90
 formed between the passage 82 and the inlet 84 of the groove 64 will also
 be supplied in this case with oil which then has the possibility, through
 this "siphon", of entering the oil receiving chamber 42 again and of
 lubricating the slide ring seal 26 on the secondary side, i.e. from the
 side of the oil receiving chamber 42.
 In a second embodiment of an inventive solution, illustrated in FIGS. 7 to
 9, the pocket 80' is designed such that it penetrates the flange 54
 completely and thus the side walls 86' of the pocket 80' extend as far as
 the stationary element 30 of the slide ring seal 26. As a result of the
 increase in size of the pocket 80', the oil bath 90' located beneath the
 oil collecting area 60' of the oil receiving chamber 42 also extends
 between the stationary element 30 and the outer seal 36, wherein a siphon
 arrangement is still created due to the transition from the pocket 80' via
 the inlet 84 into the groove 64 and this arrangement prevents any
 penetration of air into the oil receiving chamber 42 via the ascending
 channel 66.
 As for the rest, those parts of the second embodiment which are identical
 to those of the first embodiment are given the same reference numerals and
 so reference is made in full to the comments concerning the first
 embodiment with respect to the description thereof.