Patent Grant
10968913
This patent application claims the benefit of international application No. PCT/EP2016/081957 filed Dec. 20, 2016.
This patent application claims the benefit of international application No. PCT/EP2016/081957 filed Dec. 20, 2016 and German application No. 10 2015 122 443.7 filed Dec. 21, 2015, the teachings and disclosure of which are hereby incorporated in their entirety by reference thereto.
The invention relates to a refrigerant compressor installation comprising at least three compressors which are arranged in parallel between an intake conduit and a pressure conduit and which each comprise a lubricant sump unit.
There is a need in such refrigerant compressor installations to provide sufficient lubricant supply to all of the compressors.
In accordance with the invention, this object is achieved in a refrigerant compressor installation of the type described at the outset in that the compressors, when in operation, work in such a way that the respective pressures in the respective lubricant sump units of the respective compressors form a pressure cascade according to which the compressors have a successively slightly decreasing pressure in the respective lubricant sump unit in a defined cascade sequence, and in that the lubricant sump units are connected to each other in a manner corresponding to the cascade sequence by way of a lubricant conduit system for lubricant transport, and in that each lubricant sump unit comprises a port to which is connected an insert element which on the one hand establishes communication with the lubricant conduit system and on the other hand is configured such that it predetermines, for the respective lubricant sump unit, a lubricant level from which lubricant is transported to the lubricant sump unit that follows next in the cascade sequence.
The advantage of the solution in accordance with the invention is seen in particular in that it affords the possibility of ensuring, on the basis of the pressure cascade that occurs in the cascade sequence, sufficient supply of lubricant to all of the lubricant sump units, wherein it is ensured, by the predetermined lubricant level, that a sufficient amount of lubricant is present in the individual lubricant sump units.
For determining the predetermined lubricant level, it is preferably provided for each insert element to have a mouth opening of a lubricant channel leading to the lubricant conduit system, which mouth opening is located above the respective predetermined lubricant level in a direction of gravity so that when the amount of lubricant in the respective lubricant sump unit exceeds the predetermined lubricant level, the lubricant can enter the lubricant conduit system via said mouth opening and said lubricant channel in order to flow to the lubricant sump unit that follows next in the cascade sequence.
It is further advantageous, in particular where the lubricant sump unit is to be configured such that it has supplied thereto lubricant from another lubricant sump unit, for the insert elements of the compressors which are in each case located between two compressors in the cascade sequence to have a mouth opening of a lubricant channel leading to the lubricant conduit system, which mouth opening is located below the predetermined lubricant level in a direction of gravity, wherein said lubricant channel and said mouth opening afford the possibility of supplying lubricant to the corresponding lubricant sump unit, which lubricant comes from a preceding lubricant sump unit in the cascade sequence.
Advantageously, provision is made for the mouth opening located above the predetermined lubricant level in a direction of gravity and the mouth opening located below the predetermined lubricant level in a direction of gravity to be arranged in spaced relation to one another in a direction parallel to the direction of gravity.
In order to be able to detect the lubricant level of the respective lubricant sump unit for maintenance and monitoring purposes, provision is made, for example, for a sensor with which the lubricant level can be detected.
Preferably, provision is made for each insert element to comprise a visualization unit for visualizing the lubricant level of the respective lubricant sump unit.
The visualization unit is for example configured such that it provides an image indicating the lubricant level, said image being generated, for example, by electronic or optical imaging.
In particular, for the sake of simplicity of the solution, it is advantageous for the visualization unit to comprise, adjacent to a lubricant bath of the respective lubricant sump unit that extends into the insert element, a sight glass in which the lubricant level can be viewed.
Furthermore, it is preferably provided for each insert element to comprise a visualization unit for visualizing a flow of lubricant to a further lubricant sump unit.
To this end, it is preferably also provided for the visualization unit to comprise a sight glass which allows viewing a flow of lubricant to the lubricant conduit system.
No details have been given so far as to the configuration of the lubricant conduit system.
In principle, the lubricant conduit system could be configured such that it comprises a lubricant conduit with branches leading to each of the insert elements.
A particularly advantageous solution provides for the lubricant conduit system to comprise connection conduits connecting insert elements succeeding each other in the cascade sequence so that each of the connection conduits interconnects only two successive insert elements.
In this case, it is in particular provided for the connection conduit to in each case connect a lubricant channel of the one insert element having one of the mouth openings to a lubricant channel of the other insert element having one of the mouth openings.
In the case of insert elements which comprise a lubricant channel having a mouth opening located above the predetermined lubricant level in a direction of gravity and a lubricant channel having a mouth opening below the respective predetermined lubricant level in a direction of gravity, provision is made for the connection conduit to establish communication between the lubricant channel having a mouth opening located above the predetermined lubricant level in a direction of gravity and the lubricant channel having a mouth opening located below the respective predetermined lubricant level so that thereby flow into the respective lubricant bath is via the mouth opening located below the respective predetermined lubricant level and flow out of the respective lubricant bath is via the mouth opening located above the predetermined lubricant level, which, in particular, results in that when lubricant is transferred from one lubricant sump unit to the other lubricant sump unit, turbulence in said lubricant is kept as low as possible.
No details have been given so far as to the formation of the pressure cascade in the individual lubricant sump units.
Thus, it is preferably provided that the pressure level in the respective lubricant sump unit of the respective compressor is determined by the configuration of the intake conduit.
In particular, an advantageous configuration of the compressors provides for these to be configured such that the pressure in the respective lubricant sump unit is correlated with the suction pressure of the respective compressor.
It is particularly advantageous for the pressure in the respective lubricant sump unit to correspond to the suction pressure of the respective compressor.
The invention can be implemented in a particularly advantageous manner if the port to which the insert element is connected is a standard port for detecting the lubricant level.
No details have been given so far as to the supply to the individual compressors.
Thus, it is preferably provided for the intake conduit system to be configured such that a first compressor in the cascade sequence has the largest amount of lubricant supplied thereto from the intake conduit system, i.e. that the intake conduit system is configured such that lubricant precipitating therein enters the first compressor in the cascade sequence.
Furthermore, it is preferably provided for the intake conduit system to be configured such that the compressors following the first compressor in the cascade sequence receive lesser amounts of lubricant from the intake conduit system.
In particular, provision is made for the intake conduit system to be configured such that the compressors succeeding one another in the cascade sequence in each case receive lesser amounts of lubricant from the intake conduit system in a manner corresponding to their position in the cascade sequence.
No details have been given so far as to the operation of the individual compressors of the refrigerant compressor installation, in particular for the case when individual ones of the compressors are to be shut off.
Thus, it is in particular provided for the refrigerant compressor installation to comprise a controller for the individual compressors which ensures that when individual compressors are shut off, the compressors that are still running are always arranged next to one another in the cascade sequence.
Further features and advantages of the solution in accordance with the invention are the subject of the following description and drawings of a number of exemplary embodiments.
An exemplary embodiment of a refrigerant compressor installation 10, shown in its entirety in
Furthermore, individual pressure conduits 24a to 24d lead from the compressors 12a to 12d to the common pressure conduit 16.
It is preferred for the compressors 12a to 12d to be of identical configuration, wherein each of said compressors 12 comprises an outer housing 32 in which a compressor unit 34 is provided, for example in the form of a scroll compressor unit having two intermeshing scroll bodies 36 and 38, wherein, for example, the scroll body 36 is arranged in a stationary manner within the outer housing 32, while the scroll body 38 is driven for orbital movement.
For driving the compressor unit 34, a drive motor, generally designated at 42, is provided in the outer housing 32, said drive motor 42 driving the scroll body 38 via an eccentric drive 44.
The drive motor 42, configured as an electric motor, comprises a stator 46 and a rotor 48 which is mounted on a drive shaft 52 which, in turn, is supported in bearing units 54 and 56 for rotation relative to the outer housing 32 about a drive shaft axis 58.
By way of example, the drive shaft 52 is provided with a lubricant channel 62 which extends from a first drive shaft end 64 to a second drive shaft end 66 at a slight angle to the drive shaft axis 58, wherein the second drive shaft end 66 is associated with the eccentric drive 44, whereby the eccentric drive 44 is lubricated via the the lubricant channel 62.
The first drive shaft end 64 faces towards a lubricant sump unit, generally designed at 72, which, as viewed in a direction of gravity, is formed in a low-lying area of the outer housing 32, in the present instance that of a compressor having a substantially vertically extending drive shaft axis 58, by a bowl-shaped bottom body 74 of the outer housing 32, wherein a lubricant bath 76 forms in the bottom body 74, said lubricant bath 76 extending to a bath surface 78 which preferably still lies within the bottom body 74 and whose location in the direction of gravity provides an indication of the level of lubricant.
In particular, the bottom body 74 here represents an endwise closure of a cylindrical shell body 82 of the outer housing 32 which, on the side opposite the bottom body 74, is closed off by a cover body 84.
For drawing lubricant from the lubricant bath 76 into the lubricant channel 62, a suction snout 86 extends from the first drive shaft end 64 of the drive shaft 52 into the lubricant bath 76 so that the suction snout 86 is capable of picking up lubricant from below the bath surface 78 of the lubricant bath 76 and feeding same to the lubricant channel 62, in particular wherein the pumping action that is exerted on the lubricant when the drive shaft 52 is rotated is realized by virtue of the lubricant channel 62 being inclined at an oblique angle to the drive shaft axis 58 and the centrifugal forces generated thereby.
Preferably, the outer housing 32 is provided with a suction port 92 in the area between the compressor unit 34 and the lubricant sump unit 72, said suction port 92 being connected to the corresponding individual suction conduit 22.
The flow of refrigerant entering the outer housing 32 through said suction port 92—said flow of refrigerant also having lubricant entrained therein—enters an intake space 94 surrounding the drive motor 42 and flows in a direction of the compressor unit 34 while simultaneously cooling the drive motor 42, wherein lubricant separates out in the intake space 94 within the outer housing 32, which lubricant then flows in a direction of gravity into the lubricant sump unit 72 and collects in the lubricant bath 76.
This significantly reduces the amount of lubricant in the refrigerant entering the compressor unit 34, and once the lubricant has reached the lubricant bath 76, it is available to lubricate the compressor unit 34, in particular the eccentric drive 44.
The refrigerant that has been compressed in the compressor unit 34 then exits into a pressure space 96 located proximate or adjacent to the cover body 84; from there, the refrigerant then passes through the respective individual pressure conduit 24 and into the common pressure conduit 16.
Based on the separation of the lubricant from the flow of refrigerant in the intake space 94 which is located above the lubricant bath 76, the lubricant in the lubricant sump unit 72 is at a pressure that corresponds to the suction pressure PS of the refrigerant prevailing at the suction port 92 and also substantially corresponds to the suction pressure of the refrigerant drawn in by the compressor unit 34.
By way of example, the lubricant sump unit 72 is, in turn, provided with a port 102 which usually represents a standard port for a sight glass for detecting the lubricant level and which, in the present exemplary embodiment, has inserted therein an insert element, generally designated at 104, which will be described in more detail hereinafter.
The port 102 is arranged at the outer housing 32 such that it is adjacent to the lubricant bath 76 and, in particular, extends on either side of the bath surface 78 at a predetermined lubricant level.
As shown in
Thus, the lubricant conduit system 112 comprising the connection conduits 1141, 1142, 1143 together with the insert elements 104a, 104b, 104c and 104d, as a whole, represents an interconnecting system between the individual lubricant sump units 72 of the individual compressors 12a, 12b, 12c and 12d in order to achieve a sufficient distribution of the lubricant via the different lubricant sump units 72, as will be described in greater detail below.
As shown in
Thus, since the suction pressures PSa, PSb, PSc and PSd correspond to the respective pressures in the respective lubricant sump units 72a, 72b, 72c, 72d, the lubricant in the respective lubricant sump units 72a, 72b, 72c and 72d is at a different pressure in each case (
Thus, the pressures PSa, PSb, PSc and PSd together form a pressure cascade DK of successively lesser pressures having a cascade sequence KR which extends from the lubricant sump unit 72a to the lubricant sump unit 72d.
By way of example, as illustrated in
The highest pressure level PSa in the compressor 12a and hence in the lubricant sump unit 72a can be achieved in that said compressor 12a, for an intake conduit 14 of constant cross-section from which the compressors 12 draw refrigerant successively, is the last refrigerant-drawing compressor so that the lowest flow velocity of the refrigerant in the intake conduit 14 occurs at the transition to the individual suction conduit 22a, while for example the first compressor 12d having the individual suction conduit 22d draws refrigerant from the common intake conduit 14 from the area where the maximum flow velocity is encountered because the refrigerant drawn by the remaining compressors 12c, 12b and 12a also flows through the intake conduit 14 in the area of the mouth of the individual suction conduit 22d so that this is the area where the pressure of the flowing refrigerant is lowest.
Furthermore, the common intake conduit 14 having the individual suction conduits 22a to 22d is configured such that the compressor 12a, which has the highest pressure in the lubricant sump unit 72 in the pressure cascade DK, is the lead compressor which receives the largest amount of lubricant from the common intake conduit 14, while the compressors 12b, 12c and 12d which in each case lie next in the cascade direction KR receive successively lesser amounts of lubricant from the intake conduit 14 so that the last lubricant sump unit 72d receives the least amount of lubricant.
This can be achieved in that the lubricant that is already precipitating in the common intake conduit 14 is for the most part supplied to the lead compressor 12a, while the amounts of lubricant entering the other compressors 12b, 12c and 12d from the common intake conduit 14 are smaller, wherein to this end the individual suction conduit 22d projects farthest into the intake conduit 14 and the individual suction conduits 22c, 22b and 22a project successively less far into the intake conduit 14 so that lubricant precipitating and collecting in the intake conduit 14 primarily enters the individual suction conduit 22a.
As shown in
Provided within the housing body 122 is an inner space 132 which extends from a lubricant bath opening 134 facing towards the port 102 and communicating with the lubricant bath 76 to mouth openings 136 and 138 of lubricant channels 142 and 144 that are located opposite said lubricant bath opening 134, wherein the lubricant channels 142, 144 lead to ports 146 and 148 respectively for the connection conduits 114.
Furthermore, the inner space 132 is provided with a lateral opening 152 which is closed off with a sight glass 154 for visualizing a lubricant level of the lubricant bath 76 extending into the inner space 132, which lubricant level will be explained in further detail below, so that the sight glass 154 permits a view into the inner space 132, preferably across the entire cross-section thereof in a vertical direction.
In particular, the insert elements 104 in accordance with the invention are connected to the respective lubricant sump unit 72 in such a way that the mouth openings 136 and 138 and hence also the ports 146 and 148 are arranged in spaced relation to each other, one above the other, as viewed in a direction of gravity.
As shown in
However, if the amount of lubricant increases, as shown in
As the amount of lubricant continues to increase, as shown by way of example for the case of the lubricant sump unit 72″ in
A further increase in the amount of lubricant, as illustrated in
If now the mouth opening 136 of the lubricant channel 142 is utilized to discharge lubricant from the lubricant bath 76″″, then the location of the mouth opening 136 defines the predetermined lubricant level from which lubricant can be transferred from the lubricant bath 76″″ to the next lubricant sump unit 72.
If now, as illustrated in
Said lubricant then flows through the connection conduit 1141 to the next-following insert element 104b, wherein the connection conduit 1141 is connected to the port 148 of the insert element 104b, this being located below the port 146 as viewed in a direction of gravity.
Based on the pressure cascade DK, the pressure difference results in that lubricant passes from the lubricant sump unit 72a to the lubricant sump unit 72b as long as the bath surface 78″″ is not below the mouth opening 136 but is always high enough for lubricant to be permitted to enter the mouth opening 136 and hence the connection conduit 1141.
However, if, as illustrated in
Since the lead compressor 12a receives the greatest amount of lubricant from the intake conduit 14, after a finite running time of the refrigerant compressor installation has elapsed, the lubricant bath 76 of the lubricant sump unit 72 will also have a bath surface 78′ which is at a level high enough for lubricant in the insert element 104b to be allowed to enter the mouth opening 136 and hence routed from the connection conduit 1142 to the insert element 104c and also for the lubricant to enter the lubricant bath 76 of the lubricant sump unit 72c via the mouth opening 138.
In the lubricant sump unit 72c, the lubricant bath 76 is also topped up until the bath surface 78 is likewise at a level high enough for the lubricant to be allowed to enter the mouth opening 136 of the insert element 104c and to be supplied to the insert element 104d by way of the connection conduit 1143.
For simplicity, the first insert element 104a and the last insert element 104d in the cascade sequence KR are in each case configured such that in these the mouth opening 138, the lubricant channel 144 and the port 148 either do not exist or are closed off because said insert elements 104a and 104d only require the mouth opening 136, the lubricant channel 142 and the port 146; this is because it is irrelevant for the last lubricant sump unit 72d in the cascade sequence KR whether the supplied lubricant enters the lubricant bath 76 via the mouth opening 136 or the mouth opening 138.
As shown in
It is particularly advantageous if the compressor controller 162 operates in such a way that, where individual compressors 12 are shut off, these are shut off in a reverse direction from the cascade direction KR so that, for example, when one compressor is shut off, it is the compressor 12d that is shut off, and when another compressor is shut off, it is the compressor 12c that is shut off, and so on, so that the lead compressor 12a is always the last running compressor and the excess lubricant in the lubricant sump unit 72a of said lead compressor 12a is still transferred to the compressor 12 that follows next in the cascade sequence KR.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2015 122 443.7 | Dec 2015 | DE | national |
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| 20130330210 | Bonnefoi et al. | Dec 2013 | A1 |
| 20140056725 | Fraser et al. | Feb 2014 | A1 |
| 20140154105 | Xu et al. | Jun 2014 | A1 |
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| Number | Date | Country |
|---|---|---|
| 1 215 182 | Apr 1966 | DE |
| 10 2013 007887 | Dec 2013 | DE |
| 10 2013 113034 | Jun 2014 | DE |
| 02163491 | Jun 1990 | JP |
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| 2001 132645 | May 2001 | JP |
| Entry |
|---|
| English translation of JP05272477 by EPO May 4, 2020. |
| English translation of JP02163491 by EPO May 4, 2020. |
| Number | Date | Country | |
|---|---|---|---|
| 20180298905 A1 | Oct 2018 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/EP2016/081957 | Dec 2016 | US |
| Child | 16013036 | US |
