EP3394449B1 - Refrigerant compressor system - Google Patents

Description

The invention relates to a refrigerant compressor system comprising at least three compressors arranged in parallel between an intake line and a pressure line, each of which has a lubricant sump unit.

In such refrigerant compressor systems there is a need to supply all compressors with sufficient lubricant.

document US 2014/241926 shows a refrigerant compressor system, each of the compressors of the system having a lubricant sump unit with a connection to which an insert element is connected, which on the one hand establishes a connection to the lubricant line system and on the other hand is designed in such a way that it specifies a lubricant level level for the respective lubricant sump unit, from which a lubricant transport he follows.

This object is achieved according to the invention in a refrigerant compressor system of the type described at the outset in that the compressors work during operation in such a way that the respective pressures in the respective lubricant sump units of the respective compressor result in a pressure cascade according to which the compressors gradually decrease slightly in a defined cascade sequence Have pressure in the respective lubricant sump unit, that the lubricant sump units are connected to one another according to the cascade sequence for lubricant transport with a lubricant line system and that each lubricant sump unit has a connection to which an insert element is connected, which on the one hand establishes a connection to the lubricant line system and on the other hand is designed so that it specifies a lubricant level level for the respective lubricant sump unit from which lubricant can be transported to the The next lubricant sump unit in the cascade sequence takes place.

The advantage of the solution according to the invention is to be seen in the fact that with it there is the possibility of ensuring a sufficient supply of all lubricant sump units with lubricant due to the pressure cascade that occurs in the cascade sequence, whereby the specified lubricant level ensures that in the individual lubricant sump units there is a sufficient amount of lubricant.

To determine the specified lubricant level, it is preferably provided that each insert element has an orifice of a lubricant channel leading to the lubricant line system, which is located in the direction of gravity above the respective predetermined lubricant level, so that when the amount of lubricant in the respective lubricant sump unit exceeds the specified lubricant level, the lubricant via the orifice and the lubricant channel can enter the lubricant line system in order to flow to the lubricant sump unit next in the cascade order.

Furthermore, it is advantageous, in particular, if the lubricant sump unit is to be designed in such a way that this lubricant is supplied from another lubricant sump unit if the insert elements of the compressors located in the cascade sequence between two compressors have an orifice opening in the direction of gravity below the specified level of the lubricant level and leading to the lubricant line system Have lubricant channel, wherein via this lubricant channel and this mouth opening there is the possibility of supplying the corresponding lubricant sump unit with lubricant which comes from a lubricant sump unit preceding in the cascade sequence.

Advantageously, it is provided that the mouth opening above the specified lubricant level in the direction of gravity and the mouth opening below the specified lubricant level in the direction of gravity are spaced apart in the 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, a sensor is provided, for example, with which the lubricant level can be detected.

It is preferably provided that each insert element has a visualization unit for making the lubricant level of the respective lubricant sump unit visible.

The visualization unit is designed, for example, in such a way that it provides an image showing the lubricant level, which image is generated, for example, by electronic or optical imaging.

In particular, for reasons of a simple solution, it is expedient if the visualization unit comprises a sight glass adjoining a lubricant bath of the respective lubricant sump unit that extends into the insert element, in which the lubricant level can be seen.

Furthermore, it is preferably provided that each insert element has a visualization unit for making a lubricant flow to a further lubricant sump unit visible.

For this purpose, too, it is preferably provided that the visualization unit comprises a sight glass which shows a flow of lubricant to the lubricant line system.

With regard to the design of the lubricant line system, no further details have been given so far.

In principle, the lubricant line system could be designed such that it comprises a lubricant line with branches leading to each of the insert elements.

A particularly advantageous solution provides that the lubricant line system comprises connecting lines connecting successive insert elements in the cascade sequence, so that each of the connecting lines only connects two successive insert elements to one another.

In particular, it is provided in this case that the connecting line connects a lubricant channel of the one insert element having one of the mouth openings with a lubricant channel of the other insert element having one of the mouth openings.

In the case of insert elements which have a lubricant channel with an orifice opening above the specified lubricant level level in the direction of gravity and a lubricant channel with an orifice opening below the respective specified lubricant level level in the direction of gravity, it is provided that the connecting line has a connection between the lubricant channel with one above the specified lubricant level in the direction of gravity The orifice opening at the specified lubricant level level and the lubricant channel with an orifice opening below the respective specified lubricant level level, so that the inflow to the respective lubricant bath takes place via the orifice opening below the respective specified lubricant level level and an outflow from the respective lubricant bath through the above the specified lubricant level level lying mouth opening takes place, which has the particular consequence that in the Transfer of lubricant from one lubricant sump unit to the other lubricant sump unit results in the least possible turbulence of this lubricant.

With regard to the formation of the pressure cascade in the individual lubricant sump units, no further details have been given so far.

It is thus preferably provided that the pressure level in the respective lubricant sump unit of the respective compressor is determined by the design of the suction line.

In particular, an expedient design of the compressors provides that they are designed such that the pressure in the respective lubricant sump unit is correlated with the suction pressure of the respective compressor.

It is particularly useful if the pressure in the respective lubricant sump unit corresponds to the suction pressure of the respective compressor.

The invention can be implemented particularly advantageously when the connection to which the insert element is connected is a standard connection for detecting the lubricant level.

With regard to the supply of the individual compressors, no further details have been given so far.

It is preferably provided that the suction line system is designed in such a way that a first compressor in the cascade sequence is supplied with the largest amount of lubricant from the suction line system, that is, the suction line system is designed so that lubricant deposited in it is in the first compressor in the cascade order occurs.

Furthermore, it is preferably provided that the suction line system is designed in such a way that the compressors following the first compressor in the cascade sequence receive smaller quantities of lubricant from the suction line system.

In particular, it is provided that the suction line system is designed such that the compressors following one another in the cascade sequence receive smaller amounts of lubricant from the suction line system in accordance with their position in the cascade sequence.

With regard to the operation of the individual compressors of the refrigerant compressor system, in particular when individual compressors are to be switched off, no further details have so far been given.

In particular, it is provided that the refrigerant compressor system has a controller for the individual compressors which, when individual compressors are switched off, ensures that the compressors that are still working are always arranged next to one another in the cascade sequence.

Further features and advantages of the solution according to the invention are the subject matter of the following description and the graphic representation of some exemplary embodiments.

Fig. 1

eine Seitenansicht einer erfindungsgemäßen Kältemittelverdichteranlage;

Fig.2

eine Draufsicht auf die Kältemittelverdichteranlage in Richtung des Pfeils A in Fig. 1;

Fig. 3

einen vertikalen Schnitt durch einen beispielhaften Verdichter der Kältemittelverdichteranlage;

Fig. 4

eine Darstellung der Kältemittelverdichteranlage mit der sich in den einzelnen Verdichtern der Kältemittelverdichteranlage ausbildenden Druckkaskade;

Fig. 5

eine vergrößerte Darstellung des Bereichs B in Fig. 3;

Fig. 6

eine Ansicht eines Einsatzelements in Richtung des Pfeils C in Fig. 5;

Fig. 7

eine perspektivische Darstellung des Einsatzelements;

Fig. 8

eine schematische Darstellung des Einsatzelements in Relation zu einem Schmiermittelbad dessen Badoberfläche unterhalb eines vorgegebenen Schmiermittelstandes liegt;

Fig. 9

eine Darstellung entsprechend Fig. 8, wobei die Badoberfläche des Schmiermittelbades so hoch liegt, dass die Badoberfläche in einem Schauglas des Einsatzelements erkennbar ist;

Fig. 10

eine Darstellung entsprechend Fig. 8, wobei die Badoberfläche des Schmiermittelbades den vorgegebenen Schmiermittelstand erreicht;

Fig. 11

eine Darstellung ähnlich Fig. 8, wobei die Badoberfläche des Schmiermittelbads höher liegt als der vorgegebene Schmiermittelstand, so dass Schmiermittel über das Einsatzelement in das Schmiermittelleitungssystem und von dem Schmiermittelleitungssystem in den nächstfolgenden Verdichter fließt und

Fig. 12

eine Darstellung der Kältemittelverdichteranlage ähnlich Fig. 1 mit Darstellung der einzelnen Einsatzelemente und der Verbindungsleitungen des Schmiermittelleitungssystems zwischen den einzelnen Einsatzelementen.

In the drawing show:

Fig. 1

a side view of a refrigerant compressor system according to the invention;

Fig. 2

a plan view of the refrigerant compressor system in the direction of arrow A in Fig. 1 ;

Fig. 3

a vertical section through an exemplary compressor of the refrigerant compressor system;

Fig. 4

a representation of the refrigerant compressor system with the pressure cascade forming in the individual compressors of the refrigerant compressor system;

Fig. 5

an enlarged view of the area B in Fig. 3 ;

Fig. 6

a view of an insert element in the direction of arrow C in FIG Fig. 5 ;

Fig. 7

a perspective view of the insert element;

Fig. 8

a schematic representation of the insert element in relation to a lubricant bath, the bath surface of which is below a predetermined lubricant level;

Fig. 9

a representation accordingly Fig. 8 wherein the bath surface of the lubricant bath is so high that the bath surface can be seen in a sight glass of the insert element;

Fig. 10

a representation accordingly Fig. 8 wherein the bath surface of the lubricant bath reaches the predetermined lubricant level;

Fig. 11

a representation similar Fig. 8 , wherein the bath surface of the lubricant bath is higher than the specified lubricant level, so that lubricant flows via the insert element into the lubricant line system and from the lubricant line system into the next compressor and

Fig. 12

a representation of the refrigerant compressor system similar Fig. 1 with representation of the individual insert elements and the connecting lines of the lubricant line system between the individual insert elements.

One in the Fig. 1 and 2 The embodiment of a refrigerant compressor system 10 shown as a whole comprises a plurality, for example four, compressors 12a to 12d, which are arranged in parallel between a common suction line 14 and a common pressure line 16 and in the Operate in parallel, with individual suction lines 22a to 22d leading from the common suction line 14 to the individual compressors 12a to 12d, which together with the suction line 14 form an suction line system 20.

Furthermore, individual pressure lines 24a to 24d lead from the compressors 12a to 12d to the common pressure line 16.

The compressors 12a to 12d are preferably constructed identically, each of these compressors 12 having an outer housing 32 in which a compressor unit 34, for example in the form of a scroll compressor unit with two interlocking spiral bodies 36 and 38, is provided, for example the spiral body 36 being stationary in the Outer housing 32 is arranged while the spiral body 38 is driven orbiting.

To drive the compressor unit 34, a drive motor designated as a whole with 42 is provided in the outer housing 32, which drives the spiral body 38 via an eccentric drive 44.

The drive motor 42, designed as an electric motor, comprises a stator 46 and a rotor 48, which is seated on a drive shaft 52, which in turn is rotatably supported relative to the outer housing 32 in bearing units 54 and 56 about a drive shaft axis 58.

The drive shaft 52 is provided with a lubricant channel 62, for example, which runs at a small angle to the drive shaft axis 58 from a first drive shaft end 64 to a second drive shaft end 66, the second drive shaft end 66 being assigned to the eccentric drive 44 and consequently a lubrication of the Eccentric drive 44 takes place.

The first drive shaft end 64 faces a lubricant sump unit designated as a whole as 72, which is formed in an area of the outer housing 32 that is low in the direction of gravity, in the present case a compressor with an essentially vertical drive shaft axis 58, by a shell-shaped bottom body 74 of the outer housing 32, wherein a lubricant bath 76 is formed in the base body 74, which extends up to a bath surface 78 which is preferably still within the base body 74 and whose position in the direction of gravity shows the lubricant level.

In this case, the base body 74 in particular represents an end-side closure of a cylindrical jacket body 82 of the outer housing 32, which is closed on the side opposite the base body 74 by a cover body 84.

To suck in lubricant from the lubricant bath 76 into the lubricant channel 62, a suction nozzle 86 extends from the first drive shaft end 64 of the drive shaft 52 into the lubricant bath 76, so that it is able to take up lubricant below the bath surface 78 of the lubricant bath 76 and to the lubricant channel 62, in particular the pumping action of the lubricant when the drive shaft 52 rotates through the lubricant channel 62 running obliquely to the drive shaft axis 58 and the centrifugal forces occurring as a result.

The outer housing 32 is preferably provided with a suction connection 92 in the area between the compressor unit 34 and the lubricant sump unit 72, which is connected to the corresponding individual suction line 22.

The refrigerant entering the outer housing 32 through this suction connection 92, which also carries lubricant, enters a suction space 94 surrounding the drive motor 42, and flows with simultaneous cooling of the drive motor 42 in the direction of the compressor unit 34, with the suction space 94 within the Outer housing 32 a separation of lubricant takes place, which then flows in the direction of gravity to the lubricant sump unit 72 and collects in the lubricant bath 76.

The lubricant content of the refrigerant entering the compressor unit 34 is thus significantly reduced and the lubricant is available for the lubrication of the compressor unit 34, in particular the eccentric drive 44, after reaching the lubricant bath 76.

The refrigerant compressed in the compressor unit 34 then exits into a pressure chamber 96 located close to the cover body 84 or adjoining it, from which it then passes via the respective individual pressure line 24 into the common pressure line 16.

Due to the separation of the lubricant from the refrigerant flow in the suction chamber 94, which is above the lubricant bath 76, the lubricant is present in the lubricant sump unit 72 at a pressure which corresponds to the suction pressure PS of the refrigerant present at the suction connection 92 and also essentially the suction pressure of the corresponds to the compressor unit 34 sucked in refrigerant.

The lubricant sump unit 72 is in turn provided with a connection 102, which usually represents a standard connection for a sight glass for detecting the lubricant level, in which in the present exemplary embodiment an insert element designated as a whole with 104 is inserted, which is described in detail below .

The connection 102 is arranged on the outer housing 32 in such a way that it adjoins the lubricant bath 76 and, in particular, the connection 102 extends on both sides of the bath surface 78 at a predetermined lubricant level.

As in Fig. 1 and 2 shown, each of these insert elements 104a to 104d of the respective compressor 12a to 12d establishes a connection to a lubricant line system designated as a whole with 112, which in each case comprises connecting lines 114 ₁ , 114 ₂ , 114 ₃ running between two insert elements 104 Refrigerant compressor system 10 with a total of four compressors 12a to 12d, the connecting line 114 ₁ , which connects insert elements 104a and 104b, the connecting line 114 ₂ , the insert elements 104b and 104c and the connecting line 114 ₃ , which connects insert elements 104c and 104d.

Thus, the lubricant line system 112 with the connecting lines 114 ₁ , 114 ₂ and 114 ₃ together with the insert elements 104a, 104b, 104c and 104d represent an overall network system between the individual lubricant sump units 72 of the individual compressors 12a, 12b, 12c and 12d in order to achieve a sufficient To achieve distribution of the lubricant over the various lubricant sump units 72, as will be described in detail below.

As in Fig. 4 In the refrigerant compressor system 10 according to the invention, the common suction line 14 with the individual suction lines 22a to 22d opening into it is designed so that one of the compressors 12, for example the compressor 12a, has a suction pressure PSa within the outer housing 32 that is greater than the suction pressure PSb in the compressor 12b, which in turn is greater than the suction pressure PSc in the compressor 12c, this suction pressure PSc in turn being greater than the suction pressure PSd in the compressor 12d.

Since the suction pressures PSa, PSb, PSc and PSd also correspond to the respective pressure in the respective lubricant sump unit 72a, 72b, 72c, 72d, the lubricant in the respective lubricant sump units 72a, 72b, 72c and 72d is under a different pressure ( Fig. 4 ).

The pressures PSa, PSb, PSc and PSd thus form a total of a pressure cascade DK of lower pressures in each step, with a cascade sequence KR which extends from the lubricant sump unit 72a to the lubricant sump unit 72d.

For example, the pressure PSa is in the order of magnitude of one or a few tenths of a bar greater than the pressure PSb and this is in turn one or a few tenths of a bar greater than the pressure PSc and the pressure PSc is also in turn one or a few tenths of a bar greater than the pressure PSd, as in Fig. 4 shown, so that the pressure cascade DK arises, in which in a cascade direction KR the pressure gradually decreases from the one lubricant sump unit 72 to the next lubricant sump unit 72 in the cascade sequence KR.

The highest pressure level PSa in the compressor 12a and thus in the lubricant sump unit 72a can be achieved in that, in the case of a suction line 14 with a constant cross section, from which the compressors 12 suction refrigerant one after the other, it is the last compressor to suck in refrigerant, so that the flow speed of the refrigerant in suction line 14 is the smallest at the transition to individual suction line 22a, while, for example, first compressor 12d with individual suction line 22d sucks in refrigerant from the common suction line 14 from the area with maximum flow velocity, since the refrigerant sucked in by other compressors 12c, 12b and 12a also flows through the suction line 14 in the area of the confluence of the individual suction line 22d, so that the lowest pressure of the flowing refrigerant is present in this area.

Furthermore, the common suction line 14 with the individual suction lines 22a to 22d is designed so that the compressor 12a, which in the pressure cascade DK has the highest pressure in the lubricant sump unit 72, is the lead compressor which receives the largest amount of lubricant from the common suction line 14, while the compressors 12b, 12c and 12d closest in each case in the cascade direction KR receive successively less lubricant from the intake line 14, so that the last lubricant sump unit 72d receives the least amount of lubricant.

This can be achieved in that the lubricant already separating in the common suction line 14 is for the most part fed to the lead compressor 12a, while the proportions of the lubricant entering the other compressors 12b, 12c and 12d from the common suction line 14 are lower, with this the individual suction line 22d protrudes the furthest into the suction line 14 and the individual suction line 22c, 22b and 22a gradually protrude less far into the suction line 14, so that the lubricant that collects in the suction line 14 primarily enters the individual suction line 22a.

As in the Figures 5 to 7 As shown, each of the insert elements 104 comprises a housing body 122, which is provided at a first end 124 with a connector 126 which can be connected to the connection 102, for example by means of a union nut 128.

In this case, an interior space 132 is provided within the housing body 122, which extends from a lubricant bath opening 134 facing the connection 102 and communicating with the lubricant bath 76 to the mouth openings 136 and 138 of lubricant channels 142 and 144 opposite this lubricant bath opening 134, the lubricant channels 142, 144 each lead to connections 146 and 148 for the connecting lines 114.

Furthermore, the interior 132 is also provided with a lateral opening 152, which is closed with a sight glass 154 to visualize a lubricant level, described in detail below, of the lubricant bath 76 extending into the interior 132, so that the sight glass 154 can see into the interior 132, preferably over its entire cross section in the vertical direction.

In particular, the insert elements 104 according to the invention are connected to the respective lubricant sump unit 72 in such a way that the mouth openings 136 and 138 and thus also the connections 146 and 148 are arranged one above the other at a distance in the direction of gravity.

As in the Figs. 8-11 as shown in Fig. 8 shown, a small amount of lubricant introduced into the respective compressor 12 to a lubricant bath 76 ', the lubricant level indicating bath surface 78' is located in the direction of gravity below the connection 102, so that no lubricant can enter the interior 132 of the insert element 104.

However, if the amount of lubricant increases, as in Fig. 9 shown, the bath surface 78 ″ of the lubricant bath 76 ″ in this case of the lubricant sump unit 72 ″ so high that the bath surface 78 ″ can also be seen in the sight glass 154, the lubricant already being so high that it could enter the orifice 138.

With a further increase in the amount of lubricant, for example in the case of the lubricant sump unit 72 '"in Fig. 10 As shown, the bath surface 78 ′ ″ of the lubricant bath 76 ′ ″ is so high that it lies above the mouth opening 138 and can also be clearly seen in the sight glass 154.

Another increase in the amount of lubricant, shown in Fig. 11 As shown in the case of the lubricant sump unit 72 ″ ″, the bath surface 78 ″ ″ of the lubricant bath 76 ″ ″ can also be seen in the sight glass 154 and lubricant can also enter the mouth opening 136.

If the orifice 136 of the lubricant channel 142 is now used to discharge lubricant from the lubricant bath 76 "", the position of the orifice 136 defines the specified lubricant level from which lubricant can be passed on from the lubricant bath 76 "" to the next lubricant sump unit 72.

Is now like in Fig. 12 shown, in the case of the insert element 104a, the connecting line 114 _{1 is} connected to the connection 146 which is assigned to the first opening 136, then lubricant enters the connecting line 114 ₁ when the bath surface 78 ″ ″ lies above the opening 136, as in FIG Fig. 11 shown.

This lubricant then flows through the connecting line 114 ₁ to the next following insert element 104b, the connecting line 114 _{1 being} connected to the connection 148 of the insert element 104b, which is located below the connection 146 in the direction of gravity.

Due to the pressure cascade DK, the pressure difference means that lubricant passes from the lubricant sump unit 72a into the lubricant sump unit 72b as long as the bath surface 78 ″ ″ is not below the mouth opening 136, but is always so high that lubricant enters the mouth opening 136 and thus can also enter the connecting line 114 ₁ .

However, if the bath surface is 78 ', 78 "and 78'", such as in FIG Figures 8, 9 and 10 shown, below the orifice 136, only refrigerant flows through the connecting line 114 ₁ into the lubricant sump unit 72b, due to the pressure difference existing through the pressure cascade DK.

Since the lead compressor 12a receives the largest amount of lubricant from the suction line 14, after a finite operating time of the refrigerant compressor system, the lubricant bath 76 of the lubricant sump unit 72 will also have a bath surface 78 "" which is so high that lubricant can enter the opening 136 in the insert element 104b and can thus be guided from the connecting line 114 ₂ to the insert element 104c, also in such a way that the lubricant enters the lubricant bath 76 of the lubricant sump unit 72c via the mouth opening 138.

In this lubricant sump unit 72c, too, the lubricant bath 76 is filled until the bath surface 78 is also high enough for lubricant to enter the mouth opening 136 of the insert element 104c and to be fed to the insert element 104d by means of the lubricant line 114 ₃ .

For the sake of simplicity, the first insert element 104a and the last insert element 104d in the cascade sequence KR are designed in such a way that the mouth opening 138, the lubricant channel 144 and the connection 148 are either not present or closed, since in these only the mouth opening 136 , the lubricant channel 142 and the connection 146 is necessary, because with the last lubricant sump unit 72d in the cascade sequence KR it is irrelevant whether the supplied lubricant enters the lubricant bath 76 via the orifice 136 or the orifice 138.

As in Fig. 12 shown, a compressor control 162 is provided to control the individual compressors 12a, 12b, 12c and 12d of the refrigerant compression system 10, which ensures that when individual compressors 12 are switched off, the remaining working compressors 12 are next to each other in the cascade sequence KR, so that always there is the possibility of transferring lubricant from a lubricant sump unit 72 located in the pressure cascade DK at a higher pressure level to a lubricant sump unit 72 closest in the cascade sequence KR, so that the working compressors are always supplied with sufficient lubricant.

It is particularly advantageous if the compressor control 162 works in such a way that when individual compressors 12 are switched off, the switch-off takes place in the opposite direction to the cascade direction KR, so that, for example, when one compressor is switched off, the compressor 12d is switched off and when another compressor is switched off, the Compressor 12c and so on, so that the lead compressor 12a is always the last compressor still running and the excess lubricant in the lubricant sump unit 72a of this lead compressor 12a is still transferred to the other compressors 12 following in the cascade sequence KR.

Claims (15)

1. Refrigerant compressor installation (10), comprising at least three compressors (12) which are arranged in parallel between an intake conduit (14) and a pressure conduit (16) and which each comprise a lubricant sump unit (72), wherein each lubricant sump unit (72) comprises a port (102) to which is connected an insert element (104) which on the one hand establishes communication with a lubricant conduit system (112) and on the other hand is configured such that it predetermines, for the respective lubricant sump unit (72), a lubricant level from which lubricant is transported,
   characterized in that the compressors (12), when in operation, work in such a way that the respective pressures in the respective lubricant sump units (72) of the respective compressors (12) form a pressure cascade (DK) according to which the compressors (12) have a successively slightly decreasing pressure in the respective lubricant sump unit (72) in a defined cascade sequence (KR), in that the lubricant sump units (72) are connected to each other in a manner corresponding to the cascade sequence (KR) by means of the insert element (104) by way of the lubricant conduit system (112) for lubricant transport in such a way that lubricant is transported from each lubricant sump unit (72) to the lubricant sump unit (72) that follows next in the cascade sequence (KR).
2. Refrigerant compressor installation in accordance with any one of the preceding claims, characterized in that each insert element (104) has a mouth opening (136) of a lubricant channel (142) leading to the lubricant conduit system (112), which mouth opening (136) is located above the respective predetermined lubricant level in a direction of gravity.
3. Refrigerant compressor installation in accordance with any one of the preceding claims, characterized in that the insert elements (104) of the compressors (12) which are in each case located between two compressors (12) in the cascade sequence (KR) have a mouth opening (138) of a lubricant channel (144) leading to the lubricant conduit system (112), which mouth opening (138) is located below the predetermined lubricant level in a direction of gravity.
4. Refrigerant compressor installation in accordance with claim 2 and 3, characterized in that the mouth opening (136) located above the predetermined lubricant level in a direction of gravity and the mouth opening (138) located below the predetermined lubricant level in a direction of gravity are arranged in spaced relation to one another in a direction parallel to the direction of gravity.
5. Refrigerant compressor installation in accordance with any one of the preceding claims, characterized in that each insert element (104) comprises a visualization unit (152, 154) for visualizing the lubricant level in the respective lubricant sump unit (72).
6. Refrigerant compressor installation in accordance with claim 5, characterized in that the visualization unit (152, 154) comprises, adjacent to a lubricant bath (76) of the respective lubricant sump unit (72) that extends into the insert element (104), a sight glass (154) in which the lubricant level is viewable.
7. Refrigerant compressor installation in accordance with any one of the preceding claims, characterized in that each insert element (104) comprises a visualization unit (152, 154) for visualizing a flow of lubricant to a further lubricant sump unit (72).
8. Refrigerant compressor installation in accordance with claim 7, characterized in that the visualization unit (152, 154) comprises a sight glass (154) which allows viewing a flow of lubricant to the lubricant conduit system (112).
9. Refrigerant compressor installation in accordance with any one of claims 2 to 8, characterized in that the lubricant conduit system (112) comprises connection conduits (114) connecting insert elements (104) succeeding each other in the cascade sequence (KR), and in that in particular the connection conduit (114) in each case connects a lubricant channel (142, 144) of the one insert element (104) having one of the mouth openings (136, 138) to a lubricant channel (142, 144) of the other insert element (104) having one of the mouth openings (136, 138).
10. Refrigerant compressor installation in accordance with claim 9, characterized in that the connection conduit (114) establishes communication between the lubricant channel (142) having a mouth opening (136) located above the predetermined lubricant level in a direction of gravity and the lubricant channel (144) having a mouth opening (138) located below the respective predetermined lubricant level in a direction of gravity.
11. Refrigerant compressor installation in accordance with any one of the preceding claims, characterized in that the intake conduit system (14, 22) is configured in such a way that the pressure level in the respective lubricant sump unit (72) of the respective compressor (12) is determined, and in that in particular the compressors (12) are configured such that the pressure in the respective lubricant sump unit (72) is correlated with the suction pressure of the respective compressor (12), and in that in particular the pressure in the respective lubricant sump unit (72) corresponds to the suction pressure of the respective compressor (12).
12. Refrigerant compressor installation in accordance with any one of the preceding claims, characterized in that the port (102) to which the insert element (104) is connected is a standard port (102) for a sight glass for detecting the lubricant level.
13. Refrigerant compressor installation in accordance with claim 11, characterized in that the intake conduit system (14, 22) is configured such that a first compressor (12) in the cascade sequence (KR) has the largest amount of lubricant supplied thereto from the intake conduit system (14, 22), and in that in particular the intake conduit system (14, 22) is configured such that the compressors (12) following the first compressor (12a) in the cascade sequence (KR) receive lesser amounts of lubricant from the intake conduit system (14, 22)
14. Refrigerant compressor installation in accordance with claim 13, characterized in that the intake conduit system (14, 22) is configured such that the compressors (12) succeeding one another in the cascade sequence (KR) in each case receive lesser amounts of lubricant from the intake conduit system (14, 22) in a manner corresponding to their position in the cascade sequence (KR).
15. Refrigerant compressor installation in accordance with any one of the preceding claims, characterized in that the refrigerant compressor installation comprises a controller (162) for the individual compressors (12) which ensures that when individual compressors (12) are shut off, the compressors (12) that are still running are always arranged next to one another in the cascade sequence (KR).

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