EP3440358B9 - Screw compressor - Google Patents

Description

The invention relates to a screw compressor comprising a compressor housing with a screw rotor space arranged in this housing, two screw rotors which are arranged in the screw rotor space and are each mounted on the compressor housing such that they can rotate about a screw rotor axis, which engage in one another with their screw contours and each interact with compression wall surfaces which adjoin and partially enclose them , in order to take up gaseous medium supplied via a low-pressure space arranged in the compressor housing and release it in the region of a high-pressure space arranged in the compressor housing, the gaseous medium being enclosed at low pressure with an intake volume in compression chambers formed between the screw contours and compression wall surfaces adjoining them and compressed to an end volume at high pressure is, as well as two running in a slide channel of the compressor housing in a parallel to the screw rotor axes Control slides arranged one behind the other in the displacement direction and adjoining both screw rotors with slide compression wall surfaces, which are movable in the displacement direction, a first control slide being arranged to influence the end volume and a second control slide to be arranged to influence the initial volume, the first control slide and the second control slide facing each other in a compound position End faces close to one another and can be moved together in the displacement direction and can be positioned in a separated position at a distance from one another to form a gap.

Such screw compressors are from US 4,516,914A famous.

With these, there is the problem of being able to implement the transition of the control slide from the connected position to the disconnected position as reliably as possible, starting from different connected positions along the slide channel.

In a screw compressor of the type described above, this object is achieved according to the invention in that the control slides form an inflow space at least in a transitional position between the connected position and the disconnected position, into which the medium to be compressed flows from one of the compression chambers by being between the facing end faces of the control slides and that one of the control slides is provided with at least one discharge outlet adjacent to the inflow space, through which the medium from the inflow space enters an outflow opening on the slide channel that overlaps with the outflow outlet in this transitional position.

The advantage of the solution according to the invention can be seen in particular in the fact that it creates the possibility of obtaining defined flow conditions for the medium flowing out of the inflow chamber in the transitional position, which on the other hand in turn lead to defined pressure conditions in the region of the end regions of the control slides facing one another and thus allow a reliable transition from the composite position of the spool in their disconnected position.

With regard to the design of the inflow space, no further details have been given so far.

An advantageous solution provides that the inflow space extends into a central recess of one of the control slides.

On the one hand, this creates the possibility of enlarging the inflow space beyond the space between the control slides and, moreover, the possibility of designing the control slide provided with the inflow space with a lower mass and thus making it more reactive.

In principle, the central recess could be provided in the first or in the second control slide.

Since the second spool is generally moved relative to the first spool during the transition from the connected position to the disconnected position, it is advantageous if the central recess is provided in the second spool so that its mass can be reduced.

In addition, it is preferably provided that the at least one outflow outlet is arranged in the second spool valve and thus the outflow opening provided in the transitional position with the outflow outlet can be arranged in the slide channel as close as possible to the low-pressure side.

In this case, it is then also expediently provided that the outflow outlet opens into the central recess of the second control slide.

Furthermore, no further details were given with regard to the inflow space.

It is also advantageous if the inflow space also extends into an intermediate space delimited by the mutually facing end regions of the control slides and the slide channel.

So far, the position of the outflow opening on the slide channel has not been specified. It is advantageously provided that the slide channel is provided with at least one lateral outflow opening, ie the outflow opening is not on the front side of the slide channel but in longitudinal sides of the slide channel extending parallel to the direction of displacement.

Furthermore, it is preferably provided that the outflow outlet is arranged in a side wall area of the control slide that has it.

It is particularly favorable if, in the disconnected position, the outflow opening of the slide channel at least partially overlaps the intermediate space formed between the end regions of the control slides, so that in the disconnected position the medium essentially does not enter the outflow opening via the outflow outlet, but rather directly from the intermediate space between the control slides can enter the outflow outlet.

As an alternative or in addition to the features described so far, the object mentioned at the outset is also achieved according to the invention in that the control slides are designed at their end regions facing one another in such a way that during a transition from the connected position to the disconnected position, they enter a first transitional position following the connected position first throttle gap forms with a transverse to the displacement direction gap width.

Such a first throttle gap makes it possible for the medium emerging from the compression chamber to enter the intermediate space between the control slides and thus in particular also in the inflow space in a throttled manner.

It is therefore particularly favorable if the first throttle gap is arranged offset in the displacement direction relative to the end faces of the control slides facing one another. This creates the possibility of forming the throttle gap independently of the gap formed between the end faces.

Furthermore, it is particularly advantageous if the first throttle gap has a smaller gap width in the first transitional position than the gap formed between the end faces of the control slides, so that the outflow of the medium can be defined exclusively through the throttle gap and thus the possibility is created in which first transitional position to provide defined flow conditions for the outflowing medium.

It is preferably also provided that the first throttle gap with its gap width is present over a distance in the displacement direction that is greater than the gap width of the throttle gap, so that the first transitional position can be realized over a significant defined distance in the displacement direction.

The first throttling gap can be designed in a wide variety of ways.

An advantageous solution provides that the first throttle gap is delimited by two wall surfaces, one of which is arranged on the end area of the first control slide and the other on the end area of the second control slide.

The wall surfaces are preferably located in such a way that the wall surface formed by the end region of the first control slide runs adjacent to the end face of the first control slide.

Furthermore, it is preferably provided that the wall surface arranged on the end region of the second control slide runs adjacent to the end face of the second control slide.

With regard to the orientation of the wall surfaces, no further details have been given so far.

An advantageous solution provides that at least one of the wall surfaces runs essentially parallel to the direction of displacement.

An essentially parallel course to the displacement direction is to be understood here as meaning that the deviation from a parallel course is at most ±20°.

It is preferably provided that both wall surfaces run essentially parallel to the direction of displacement, so that the gap width does not vary during a movement in the direction of displacement in the first transitional position.

A further advantageous solution provides that the control slides are designed at their mutually facing end regions such that in a second transitional position lying between the first transitional position and the disconnected position, a second throttle gap is formed with a gap width running transversely to the direction of displacement that is greater than the Gap width of the first throttle gap.

Thus, after the first transitional position, it is possible to change to a second transitional position, in which there are also defined conditions for the medium flowing out of the compression chamber and entering the intermediate space between the control slides and thus in particular also the inflow space.

Preferably, the second throttle gap is arranged in such a way that it is delimited by at least one wall surface, which is arranged on a side of the wall surface delimiting the first throttle gap, facing away from the end face.

This wall surface is preferably set back in relation to the wall surface of this control body which delimits the first throttle gap, in order to achieve a larger gap width.

Furthermore, it is preferably provided that the second throttle gap is delimited by a wall surface which also delimits the first throttle gap.

In addition, as an alternative or in addition to the previously described embodiments, a further advantageous embodiment provides that at least one of the end faces of the control slides has a sealing edge surface adjoining the slide compression wall surfaces and on a side of the sealing edge surface opposite the slide compression wall surfaces adjoining the latter and opposite the sealing edge surface in a direction parallel to the Has displacement direction recessed or lowered inner surface.

This solution has the advantage that, firstly, the sealing edge surface of one end face can form a seal with the other end face in the connected position and, on the other hand, the recessed or lowered inner surface is available to build up a force that contributes to moving the control slides apart.

In order to obtain an adequate seal, it is provided that the sealing edge surface extends so far in the direction of the slide channel that it is still adjacent to a partial surface of the circumferential guide surface of the respective control slide, so that a reliable seal is created by the sealing edge surface with the opposite end face of the other control slide is guaranteed.

Furthermore, it is preferably provided that the inner surface, which is set back from the sealing edge surface, forms a gap space with the opposite end face in the combined position of the control slides, which gap is connected to an inflow space delimited by the control slides in the connected position and is at the same pressure level as the inflow space, so that as a result a force that is already effective in the composite position can be generated, which supports the spool valves moving apart.

It is preferably provided that the inflow chamber is at low pressure in the composite position of the control slides.

This is achieved in particular by the fact that the inflow chamber is connected to the low-pressure chamber of the compressor housing when the control slides are in the composite position, in that in the composite position an outflow outlet in one of the control slides is arranged so that it overlaps with the outflow opening on the slide channel.

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

Fig. 1

eine perspektivische Ansicht eines ersten Ausführungsbeispiels eines erfindungsgemäßen Schraubenverdichters;

Fig. 2

einen Schnitt längs Linie 2-2 in Fig. 1;

Fig. 3

einen Schnitt längs Linie 3-3 im Bereich einer Positionserfassungseinrichtung;

Fig. 4

einen vergrößerten Schnitt ähnlich Fig. 2 im Bereich der Steuerschieber bei maximaler Leistung und kleinstem Volumenverhältnis;

Fig. 5

einen Schnitt längs Linie 5-5 in Fig. 3;

Fig. 6

eine Darstellung ähnlich Fig. 4 bei maximalem Fördervolumen und größtem Volumenverhältnis;

Fig. 7

eine Darstellung ähnlich Fig. 4 in einer ersten Übergangsstellung;

Fig. 8

eine vergrößerte Darstellung eines Bereichs A in Fig. 7;

Fig. 9

eine perspektivische Darstellung des ersten und zweiten Steuerschiebers;

Fig. 10

eine perspektivische Darstellung des zweiten Steuerschiebers;

Fig. 11

eine gegenüber der Fig. 10 gedrehte perspektivische Darstellung des zweiten Steuerschiebers;

Fig. 12

einen Schnitt längs Linie 12-12 in Fig. 7;

Fig. 13

eine Darstellung ähnlich Fig. 7 in einer zweiten Übergangsstellung;

Fig. 14

eine vergrößerte Darstellung eines Bereichs B in Fig. 13 und

Fig. 15

eine Darstellung der Steuerschieber mit einer Positionserfassungseinrichtung ähnlich Fig. 4 in einer Trennstellung.

Show in the drawing:

1

a perspective view of a first embodiment of a screw compressor according to the invention;

2

a cut along line 2-2 in 1 ;

3

a section along line 3-3 in the area of a position detection device;

4

similar to an enlarged section 2 in the area of the spool valve with maximum power and the smallest volume ratio;

figure 5

a cut along line 5-5 in 3 ;

6

a representation similar 4 at maximum displacement and largest volume ratio;

7

a representation similar 4 in a first transitional position;

8

an enlarged view of an area A in 7 ;

9

a perspective view of the first and second control slide;

10

a perspective view of the second control slide;

11

one opposite the 10 rotated perspective view of the second control slide;

12

a cut along line 12-12 in 7 ;

13

a representation similar 7 in a second transitional position;

14

an enlarged view of an area B in 13 and

15

a representation of the spool with a position detection device similar 4 in a disconnected position.

a in 1 The illustrated exemplary embodiment of a screw compressor 10 according to the invention comprises a compressor housing, designated as a whole with 12, which has a suction connection 14, via which a gaseous medium to be sucked in, in particular refrigerant, is sucked in and a pressure connection 16, via which the gaseous medium compressed to high pressure, in particular the refrigerant, is delivered, has.

As in 2 and 3 shown, in a helical rotor space 18 of the compressor housing 12 are provided two helical rotors 26, 28, each rotatable about a helical rotor axis 22, 24, which engage in one another with their helical contours 32 and 34 and interact with compression wall surfaces 36 and 38 of the helical rotor chamber 18 adjoining them on the circumferential side, in order to receive a gaseous medium fed to the screw contours 32, 34 adjoining the suction side of the low-pressure chamber 42, to compress it and to release it at high pressure into a high-pressure chamber 44 in the compressor housing 12.

The gaseous medium, in particular refrigerant, is enclosed in compression chambers formed between the screw contours 32, 34 and the compression wall surfaces 36, 38 adjoining them at low pressure in an intake volume and is compressed to a final volume at high pressure.

To adapt the screw compressor 10, for example to the operating conditions required in a refrigerant circuit, the operating state of the screw compressor 10 is adjusted on the one hand with regard to the volume ratio, which indicates the relation between the maximum enclosed suction volume and the discharged end volume, and on the other hand with regard to the compressor performance, which indicates the proportion of the volume flow actually compressed by the screw compressor in relation to the maximum volume flow that can be compressed by the screw compressor 10 .

To adjust the operating status are at a first, in the Figures 2 to 8 illustrated embodiment, a first control slide 52 and a second control slide 54 arranged one behind the other in a slide channel 56 provided in the compressor housing 12, the slide channel 56 running parallel to the screw rotor axes 22, 24 and the first Control slide 52 and the second control slide 54 in the region of their non-adjacent to the screw rotor 26, 28 peripheral guide surface 58 in a defined by the slide channel 56 displacement direction 72.

The first spool valve 52 faces the high-pressure chamber 44 and is therefore arranged on the high-pressure side, and the second spool valve 54 is arranged on the low-pressure side relative to the first spool valve 52 .

Each of the two control slides 52 and 54 also has a slide compression wall surface 62 adjoining screw rotor 26 and a slide compression wall surface 64 adjoining screw rotor 28, which represent partial areas of compression wall surfaces 36 and 38, and housing compression wall surfaces 66 and 68 formed by compressor housing 12, which also Represent partial surfaces of the compression wall surfaces 36 and 38, supplement to the compression wall surfaces 36 and 38, which together with the screw contours 32 and 34 contribute to the formation of the compression chambers.

The first spool valve 52 and the second spool valve 54 are, as in Figures 2 to 15 shown, designed in such a way that they are identical insofar as they form the slide compression wall surfaces 62 and 64 as well as the peripheral guide surface 58 and thus they can be guided displaceably in the slide channel 56 of the compressor housing 12 in a single displacement direction 72 running parallel to the screw rotor axes 22, 24 .

The first control slide 52 forms an outlet edge 82 facing the high-pressure chamber 44 and defining the end volume of the compression chambers Compression chambers and thus the volume ratio co-determined.

This principle of the slide assembly is known and for example in WO 93/18307 described, to which reference is made with regard to the description of the functional principle.

As in the 2 and 4 to 15 shown, the first control slide 52 and the second control slide 54 have end faces 86 and 88, respectively, adjoining the slide compression wall surfaces 62, 64, running transversely thereto and facing one another, with which these, as for example in 4 shown, are abuttable such that the spool compression wall surfaces 62 and 64 of the first spool 52 and the second spool 54 merge into one another.

Furthermore, a compression spring 104 is preferably also provided, which serves to act on the first control slide 52 relative to the second control slide 54 in such a way that the end faces 86 and 88 can be moved away from one another.

To move the first control slide 52, as in figure 5 shown, a cylinder arrangement 112 is provided, which comprises a cylinder chamber 114 and a piston 116, the piston 116 being connected to a piston rod 118 which establishes a connection to the first control slide 52, for example with an in 2 and 4 shown extension 122 of the first control slide 52, which is arranged for example on a side opposite the end face 86 of the same.

Furthermore, the cylinder arrangement 112 is located in particular on a side of the first control slide 52 opposite the second control slide 54, preferably in a high-pressure-side housing section 124 of the compressor housing 12, which is connected to the slide channel 56 and to the high-pressure chamber 44 and thus on the low-pressure chamber 42 opposite side of the compressor housing 12 is arranged.

The second control slide 54 can be displaced by a cylinder arrangement 132, which comprises a piston 136 that can be moved in a cylinder chamber 134, with the cylinder chamber 134 extending in particular as a continuation of the slide channel 56 in a low-pressure-side housing section 142, in which, for example, drive-side bearing units for the screw rotors 26 and 28 are arranged, which can be driven via a drive shaft 143, for example.

In particular, the piston 136 is integrally formed on the second spool valve 54 and has a piston area that corresponds at least to the cross-sectional area of the second spool valve 54 .

The low-pressure side housing section 142, which accommodates the cylinder chamber 134 for the cylinder arrangement 132 for moving the second control slide 54, is located in an area of the compressor housing 12 which is arranged opposite the high-pressure side housing section 124 for accommodating the cylinder chamber 114 for the cylinder arrangement 112.

The first spool valve 52 and the second spool valve 54 can be pushed together by the cylinder assemblies 112 and 132 to such an extent that the end faces 86 and 88 abut one another in a composite position, and the two spool valves 52, 54 can also be operated together in the composite position like a single spool valve move, which extends from the suction-side closing surface 126 in the direction of the pressure-side closing surface 84 and whose outlet edge 82 contributes to determining the volume ratio, wherein, as in FIG 4 and 6 shown, the screw compressor 10 always promotes the maximum volume flow in this compound position.

Depending on the position of the outlet edge 82 relative to the closing surface 84, the volume ratio can be adjusted, which is based on the position according to FIG 4 present minimum value as the distance decreases of the outlet edge 82 rises from the end surface 84 and reaches its maximum value when the outlet edge 82 is at the minimum distance from the end surface 84 required to minimize the final volume, such as in FIG 6 shown.

If the compressor output, i.e. the volume flow actually delivered, is to vary additionally, this is done, as for example in Figures 7 to 15 shown, separating the end faces 86 and 88 by moving the control slides 52 and 54 apart into a disconnected position, in particular by moving the second control slide 54 in the direction of the low-pressure-side housing section 142.

In the disconnected position, the second control slide 54 has no effect, since the medium to be compressed flows out of the compression chamber located above the end faces 86 and 88 between the control slides 52, 54 in the direction of the slide channel 56, which is connected to the low-pressure chamber 42 via the side of the slide channel 56 in the compressor housing 12 arranged outflow openings 144 ( 2 ) and is connected to these adjoining channels in the compressor housing 12.

Discharge openings 144 lying opposite one another are preferably arranged on opposite longitudinal sides of the slide channel 56 .

The outflow openings 144 extend in particular over a region of the slide channel 12 which extends from the suction-side closing surface 126 in the direction of the pressure-side closing surface 84 .

Thus, in the disconnected position, the position of the end face 86 of the first control slide 52 defines the initial volume.

As long as the outlet edge 82 is not in a position in which it specifies the minimum possible end volume, the relation of the initial volume, specified by the end face 86, to the end volume, specified by the outlet edge 82, is not variable.

However, if the first control slide 52, as in 15 shown, is displaced so far in the direction of the high-pressure chamber 44 that the outlet edge 82 has the minimum distance from the closing surface 84 or is even displaced beyond this into an entry space 146 for the first control slide 52, which is comprised by the high-pressure chamber 44, is a variation of the initial volume 86 is possible without changing the end volume, as this then always remains minimal.

In order to eliminate the effect of the second spool valve 54 in the disconnected position, it is moved into the housing section 142 in particular by means of the cylinder arrangement 132, with the cylinder chamber 134 being dimensioned such that it also includes an insertion space 148 for the second spool valve 54 and thus the possibility manages to move the second spool 54 far enough away from the first spool 52 that the face 88 no longer affects the initial volume.

The second spool valve 54 thus makes it possible to influence the initial volume in that it either rests with its end face 88 against the end face 86 of the first spool valve 52 to form the combined position of the control slide valves 52, 54 and thus maximizes the initial volume, or with its own end face 88 in such a way can be moved far away from the end face 86 of the first spool valve 52 so that the initial volume is no longer influenced by the second spool valve 54 .

As in the 2 , 4 , 6 to 8 as well as in the Figures 9 to 11 shown in perspective, the control slides 52, 54 are stepped at their mutually facing end regions 152, 154, the second control slide 54 having a slide compression wall surfaces 62, 64 and the end face 88 and thus adjoining the screw contours 32, 34 extension 164, while the first control slide 52 has an extension 162 which protrudes beyond the end face 86 in the direction of the second control slide 54 and which in particular lies essentially in the slide channel 56 .

The extensions 164 and 162 are preferably formed in such a way that in 4 and 6 In the composite position shown, the extension 164 overlaps the extension 162 in such a way that the end faces 88 and 86 of the control slides 54 and 52 rest against one another in a sealing manner and the slide compression wall surfaces 62, 64 merge into one another.

Furthermore, the extension 164 in particular is designed in such a way that it also includes partial surfaces 172 of the peripheral guide surface 58 of the second control slide 54 adjoining the slide compression wall surfaces 62, 64 and the end face 68, so that the extension 164 in turn is also guided in the slide channel 56 ( 9 ).

Furthermore, the extension 162 in turn forms a partial surface 174 that supplements the partial surfaces 172 in the circumferential direction to form the circumferential surface 58.

The extension 162 further includes a cylindrical extension 176 which, as for example in 4 and 6 shown, forms a receptacle 178 for the compression spring 104, which, starting from this receptacle 178, extends to a support flange 182 of a central recess 184 provided in the second control slide 54 and with a force which moves the control slides 52, 54 away from one another and acts on the control slides 52 , 54 acts.

With their in the compound position ( 4 and 6 ) facing first wall surfaces 192 and 194, which extend approximately parallel to the direction of displacement 72 starting from the end faces 86, 88, the extensions 164, 162 form a first throttle gap 196 in a first transitional position occurring during the transition from the connected position to the disconnected position a first gap width SB1 running transversely to the displacement direction 72, which, as in 7 and particularly 8 shown, throttles an inflow of the medium to be compressed into an inflow space 198, which forms the central recess 184 in the second spool valve 54 and a transverse position between the spool valves 52, 54 as a result of the movement from the connected position in the direction of the disconnected position and transversely to the displacement direction of the slide channel 56 limited space 202 includes.

This leads to an outflow of the medium defined by the throttle gap 196 out of the compression chamber standing above an intermediate space 204 formed between the end faces 86, 88.

In order to allow the medium to flow optimally out of the inflow chamber 198 into the low-pressure chamber 42 in this first transitional position, the second control slide 54 is provided in the area of its side walls 214 forming the peripheral guide surfaces 58 with outflow outlets 212, in particular outflow windows 212, which in the central recess 184 delimiting side walls 214 of the second control slide 54 are arranged ( 7 , 9 to 11 ), wherein the outflow outlets 212 are positioned so that they are arranged overlapping with the side outflow openings 144 in the first transition position. In particular, the extent of the intermediate space 202 in the displacement direction 72 is so small that it does not overlap with the outflow openings 144 or does so to a significant extent.

Thus, in the first transitional position, the first throttle gap 196 is decisive for the throttling of the outflowing medium due to the flow paths designed in this way.

Is carried out starting from the first transition position (shown in 7 ) a transition to a second transitional position (shown in 13 and 14 ), the first throttle gap 196 formed between the first wall surfaces 192 and 194 of the extensions 162, 164 is ineffective, and a second throttle gap 222 is formed with a second gap width SB2 running transversely to the displacement direction 72 and with a larger cross section than the first throttle gap 196 between the wall surface 194 of the extension 164 and a wall surface 224 of the first extension 162 that is set back from the wall surface 192.

Also in the second transitional position ( 13 and 14 ) the outflow outlets 212 are arranged so that they overlap with the outflow openings 144, so that the second throttle gap 222 is decisive for throttling the outflowing medium.

Starting from the second transitional position, there is a transition to the disconnected position ( 15 ) in which the intermediate space 202 has such an extension in the displacement direction 72 that the medium can flow directly from the intermediate space 202 via the outflow openings 144 into the low-pressure space 42.

In addition, in order to have at least a partial area of the end faces 86, 88 of the control slides 52, 54 available as low-pressure surfaces already in the composite position, which result in forces counteracting the force effect of the cylinder arrangements 112 and 132, one of the end faces 86, 88 , for example as in Figures 10 and 11 shown, the end face 88 is provided with a sealing edge surface 232 adjoining the slide compression wall surfaces 62, 64 and the partial surface 172 of the guide peripheral surface 58, relative to which an inner surface 234 runs set back or lowered, so that between this inner surface 234 and end face 86 creates a gap space 236 in which there is medium under low pressure even when the control slides 52, 54 are in the connected position, so that the inner surface 234 acted upon by the low pressure and the partial area of the end face 86 facing it counteract the cylinder arrangements 112 and 132 forces that promote the transition from the connected position to the disconnected position and thus make it more reliable ( Figures 9 to 11 ).

To detect the positions of the first control slide 52 and the second control slide 54, a position detection device designated as a whole by 252 is provided, which comprises a detector element 254 that extends parallel to the displacement direction 72 of the control slides 52, 54 and thus parallel to the helical rotor axes 22, 24. which is able to detect the positions of position indicators 256 and 258.

Position indicator element 256 is rigidly coupled to first spool valve 52, specifically to extension 162 of first spool valve 52, and position indicator element 258 is coupled to second spool valve 54, specifically to that in spool channel 56 and to first spool valve 52 facing end region 154 of the same, as in particular in 15 shown.

As in 12 shown, each of these position indicator elements 256 and 258 comprises a fork body, designated as a whole with 274, which with its two fork legs 276 and 278 delimits an intermediate space 282 lying between them, through which the elongate detector element 254 runs. Each of these fork bodies 274 is coupled to the corresponding control slide 52, 54 via a connecting body 272 connected to the extension 162 or the end region 154 ( 15 ).

The connecting bodies 272, which are held on the respective control slides 52, 54, pass through an elongate, slot-shaped passage 294, which is molded into a housing wall 296 forming the slide channel 56 and has a length which, in the disconnected position, allows the second control slide 54 to be fully retracted into the drive-in space 148 and a position of the first control slide 52 with a minimum initial volume and a position of the first control slide 52 with a minimum volume ratio, i.e. maximum distance of the outlet edge 82 from the pressure-side closing surface 84, and also a position of the second control slide 54 in the compound position with the first spool 52 at maximum volume ratio and minimum volume ratio.

Each connecting body 272 connected to the respective control slide 52 or 54 forms, together with the slot-shaped passage 294, an anti-twist device for the respective control slide 52, 54, similar to a guide using a sliding block and a groove, so that there is no need to 54 grooves are to be provided which interact with sliding blocks protruding into the slide channel 56 ( 12 and 15 ).

The passage 294 is always maintained at the pressure in the low-pressure chamber 42 and thus also serves to keep the control slides 52, 54 with their peripheral guide surface 58 in contact with the slide channel 56, so that the control slides 52, 54 do not push through between the slide channel 56 and high pressure forming guide peripheral surface 58 with vane compression wall surfaces 62,64 against helical rotors 26,28.

The passage 294 is sealed against higher pressures, in particular also high pressure, by the narrowly tolerable gap between the slide channel 56 and the peripheral guide surface 58 of the control slides 52, 54.

To move the control slides 52 and 54 into the positions provided for them, as in 1 shown, a controller 318 is provided which, through the connection to the position detection device 252, is able to determine the actual positions of the control slides 52, 54.

With the controller 318, the cylinder assemblies 112 and 132 can be controlled in order to position the control slides 52, 54.

Claims (15)

1. A screw compressor (10), including a compressor housing (12) having a screw rotor chamber (18) arranged therein, two screw rotors (26, 28) that are arranged in the screw rotor chamber (18) and are mounted on the compressor housing (12), each rotatably about a respective screw rotor axis (22, 24), and engage in each other by means of their helical contours (32, 34) and each cooperate with compression wall surfaces (36, 38) which are adjacent thereto and partly surround them in order to receive gaseous medium that is supplied by way of a low-pressure chamber (42) arranged in the compressor housing (12) and to discharge it in the region of a highpressure chamber (44) that is arranged in the compressor housing (12), wherein the gaseous medium is enclosed in compression chambers that are formed between the helical contours (32, 34) and compression wall surfaces (36, 38) that are adjacent thereto with an inflow volume at low pressure and is compressed to a final volume at high pressure, and including two control sliders (52, 54) that are arranged one behind the other in a slider channel (56) of the compressor housing (12) in a direction of displacement (72) parallel to the screw rotor axes (22, 24) and are adjacent to both screw rotors (26, 28) by means of slider compression wall surfaces (62, 64) and are movable in the direction of displacement (72), wherein a first control slider (52) is arranged such that it affects the final volume and a second control slider (54) is arranged such that it affects the initial volume, wherein, in a combined position with mutually facing end surfaces (86, 88) the first control slider (52) and the second control slider (54) are sealed tightly with each other and are movable together in the direction of displacement (72) and, in a separated position, are positionable at a spacing from one another, forming an intermediate space (202),
   characterised in that, at least in a transfer position located between the combined position and the separated position, the control sliders (52, 54) form an inflow chamber (198) into which the medium to be compressed flows out of one of the compression chambers by passing between the mutually facing end surfaces (86, 88) of the control sliders (52, 54), and in that one of the control sliders is provided with at least one outflow outlet (212) that is adjacent to the inflow chamber (198) and through which the medium from the inflow chamber (198) enters an outflow opening (144) in the slider channel (56) that overlaps with the outflow outlet (212) in this transfer position.
2. A screw compressor according to claim 1, characterised in that the inflow chamber (198) extends into a central recess (184) in one of the control sliders (54).
3. A screw compressor according to claim 2, characterised in that the central recess (184) is provided in the second control slider (54).
4. A screw compressor according to one of the preceding claims, characterised in that the at least one outflow outlet (212) is arranged in the second control slider (54).
5. A screw compressor according to claim 4, characterised in that the outflow outlet (212) opens into the central recess (184) in the second control slider (54).
6. A screw compressor according to one of the preceding claims, characterised in that the inflow chamber (198) also extends into an intermediate space (202) that is delimited by the mutually facing end regions (152, 154) of the control sliders (52, 54) and the slider channel (56).
7. A screw compressor according to one of the preceding claims, characterised in that the slider channel (56) is provided with at least one lateral outflow opening (144).
8. A screw compressor according to one of the preceding claims, characterised in that the outflow outlet (212) is arranged in a side wall region of the control slider (54) to which it pertains.
9. A screw compressor according to one of the preceding claims, characterised in that, in the separated position, the outflow opening (144) of the slider channel (56) overlaps at least partly with the intermediate space (202) formed between the end regions (152, 154) of the control sliders (52, 54).
10. A screw compressor according to one of the preceding claims, characterised in that the control sliders (52, 54) take a form in their mutually facing end regions (152, 154) such that, in the event of a transfer from the combined position to the separated position, a first throttling gap (196) having a gap width that runs transversely to the direction of displacement (72) is formed in a first transfer position that comes directly after the combined position, in particular, in that the first throttling gap (196) is arranged offset in the direction of displacement (72) in relation to the mutually facing end surfaces (86, 88) of the control sliders (52, 54).
11. A screw compressor according to claim 10, characterised in that in the first transfer position the first throttling gap (196) has a smaller gap width than the gap formed between the end surfaces (86, 88) of the control sliders (52, 54).
12. A screw compressor according to one of claims 10 or 11, characterised in that the gap width of the first throttling gap (196) is present over a distance in the direction of displacement (72) that is greater than the gap width of the first throttling gap (196).
13. A screw compressor according to one of claims 10 to 12, characterised in that the first throttling gap (196) is delimited by two wall surfaces (192, 194), of which one (192) is arranged in the end region (152) of the first control slider (54) and another (194) in the end region (154) of the second control slider (54), in particular, in that the wall surface (192) that is formed by the end region (152) of the first control slider (52) extends adjacent to the end surface (86) of the first control slider (52), in particular, in that the wall surface (194) that is arranged in the end region (152) of the second control slider (54) extends adjacent to the end surface (88) of the second control slider (54).
14. A screw compressor according to one of claims 10 to 13, characterised in that at least one of the wall surfaces (192, 194) extends substantially parallel to the direction of displacement (72).
15. A screw compressor according to one of the preceding claims, characterised in that the control sliders (52, 54) take a form in their mutually facing end regions (152, 154) such that, in a second transfer position located between the first transfer position and the separated position, there is formed a second throttling gap (222) having a gap width that runs transversely to the direction of displacement (72) and is greater than the gap width of the first throttling gap (196), in particular, in that the second throttling gap (222) is delimited by at least one wall surface that is arranged on a side of the wall surface (192) delimiting the first throttling gap (196) that is remote from the end surface (86), and/or in particular, in that the second throttling gap (222) is delimited by a wall surface (194) that also delimits the first throttling gap (196).

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