Device for compressing a gaseous fluid

Abstract

Device (1) for compressing a gaseous fluid, in particular a scroll compressor, comprising a housing (2) with a wall (12) and a compression mechanism with a stationary stator (3) and a movable orbiter (4), which is driven via a drive shaft (6, 6a, 6b, 6b-1, 6b-2, 6b-3), wherein - the wall (12) and the orbiter (4) are designed to at least partially enclose a counterpressure region (13) and the wall (12) is designed between the counterpressure region (13) and a suction region (14), delimiting the counterpressure region (13) from the suction region (14), - the drive shaft (6, 6a, 6b, 6b-1, 6b-2, 6b-3) is arranged so as to protrude through an opening formed within the wall (12), wherein a shaft sealing element (15, 15a, 15b, 15b-1, 15b-2, 15b-3, 15b-4, 15c) is arranged between the drive shaft (6, 6a, 6b, 6b-1, 6b-2, 6b-3) and the wall (12) for sealing the counterpressure region (13) from the intake region (14), wherein between the drive shaft (6, 6a, 6b, 6b-1, 6b-2, 6b-3) and the shaft sealing element (15, 15a, 15b, 15b-1, 15b-2, 15b-3, 15b-4, 15c) a sealing surface (23) is formed with a through opening (24a, 24b, 24c) interrupting the sealing surface (23) and hydraulically connecting the counterpressure region (13) and the suction region (14).

Description

[0001] The invention relates to a device for compressing a gaseous fluid, in particular a scroll compressor for compressing a refrigerant. The device comprises a housing with a wall and a compression mechanism with a stationary stator and a movable orbiter. The orbiter, driven by a drive shaft, and the wall of the housing are designed to at least partially enclose a counterpressure region.

[0002] State-of-the-art compressors for mobile applications, particularly for automotive air conditioning systems, for conveying refrigerant through a refrigerant circuit, also known as refrigerant compressors, are often designed as piston compressors with variable displacement or as scroll compressors, regardless of the refrigerant. The compressors are driven either by a pulley or electrically.

[0003] Conventional scroll compressors comprise, in addition to a housing, a stationary stator with a disc-shaped base plate and a spiral wall extending from one side of the base plate, as well as a movable orbiter, also with a disc-shaped base plate and a spiral wall extending from the front of the base plate. The stator and the orbiter interact. The base plates are arranged relative to one another in such a way that the spiral walls interlock. The orbiter is moved along a circular path by means of an eccentric drive comprising a drive shaft and an intermediate element.

[0004] State-of-the-art scroll compressors also have a wall arranged within the housing and firmly connected to the housing, which is designed to delimit a backpressure area and is therefore also referred to as a backwall. Due to the backpressure prevailing within the backpressure area formed between the backwall and the orbiter, in particular a rear side of the orbiter's base plate, the orbiter is pressed against the orbiter, which, like the backwall, is fixed to the housing, with a force acting in the axial direction. The pressure force acting in the axial direction is controlled or regulated by the backpressure prevailing within the backpressure area, also referred to as contact pressure. The contact pressure level is an intermediate pressure or medium pressure between the high pressure and low pressure levels, i.e. the outlet pressure and suction pressure of the compressor. The areas subjected to high pressure and back pressure as well as to back pressure and low pressure are connected to each other, for example, via flow channels formed in the housing or inside the drive shaft with integrated expansion devices.

[0005] DE 10 2016 113 057 B4 discloses a device for compressing a gaseous fluid. The device comprises a housing with a suction pressure chamber and a high-pressure chamber, a compression mechanism, and an arrangement formed in the region of the high-pressure chamber for separating a control mass flow from a fluid-lubricant mixture for controlling the compression mechanism. The arrangement is designed with a first flow channel for diverting a main mass flow of the compressed fluid-lubricant mixture from the device and a second flow channel for directing the control mass flow within the device to the suction pressure chamber in such a way as to separate a mass flow of the gaseous fluid as a control mass flow. The second flow channel opens into a high-pressure channel in the flow direction of the control mass flow.At the outlet of the high-pressure channel, an expansion device is arranged to expand the control mass flow from a high-pressure level to a medium-pressure level. The control mass flow is directed into a region of the housing that is pressurized with gaseous fluid at the medium-pressure level.

[0006] US 10 094 379 B2 discloses a scroll compressor for compressing a refrigerant. The scroll compressor is configured to adjust a pressure prevailing in a backpressure chamber in conjunction with an outlet pressure of the refrigerant, so that a movable scroll of a compression mechanism is supported by the pressure within the backpressure chamber without any loss of performance or internal leakage.

[0007] In a controlled backpressure system, the expansion device located between the high-pressure and backpressure zones must function with great precision, as its accuracy significantly influences the intermediate pressure value, which serves as the backpressure zone. The corresponding sealing elements, especially a shaft seal, must ensure maximum tightness to prevent refrigerant from overflowing from the backpressure zone into the low-pressure zone and to define overflow of refrigerant from the high-pressure zone into the backpressure zone exclusively through the expansion device.

[0008] The shaft sealing element, which is designed to be leak-free and is intended to seal the back pressure area from the low pressure area as the intake area of the compressor between the rotating drive shaft and the counter wall of the housing, is neither lubricated nor cooled during operation of the scroll compressor, so that high rotation speeds of the drive shaft and high pressure differences lead to high friction and thus to considerable wear of the shaft sealing element, especially in the area of the drive shaft. In addition, the costs incurred for an expansion device arranged between the areas subjected to high pressure and back pressure, in particular designed as a nozzle, and the effort required for the manufacture and assembly of scroll compressors known from the prior art are very high, since, for example, a special station for assembling the expansion device on the production line is usually necessary and, following assembly, measurements for the possible pressure loss must be carried out in order to check correct assembly.

[0009] The object of the invention is to provide a device for compressing a gaseous fluid, in particular the further development of a scroll compressor, to ensure trouble-free operation with a maximum service life of the device. The device should have as few individual components as possible and be structurally simple to implement, also to minimize assembly and maintenance costs.

[0010] The problem is solved by the subject matter having the features of the independent patent claim. Further developments are specified in the dependent patent claims.

[0011] The object is achieved by a device according to the invention for compressing a gaseous fluid, in particular a scroll compressor for compressing a refrigerant circulating within a refrigerant circuit. The device has a housing with a wall and a compression mechanism with a stationary stator and a movable orbiter. The orbiter is driven via a drive shaft. The wall of the housing and the orbiter are designed to at least partially enclose a backpressure region. The wall is arranged between the backpressure region and an intake region, delimiting the backpressure region from the intake region. The drive shaft is arranged so as to project through an opening formed within the wall delimiting the backpressure region from the intake region.In addition, a shaft sealing element is provided in the area of the opening between the drive shaft and the wall to seal the back pressure area from the intake area.

[0012] According to the concept of the invention, a sealing surface with a through opening interrupting the sealing surface and hydraulically connecting the counterpressure area and the suction area is formed between the drive shaft and the shaft sealing element. The sealing surface is considered to be a contact surface on which the drive shaft and the shaft sealing element rest against each other.

[0013] The drive shaft is advantageously circular-cylindrical in shape, while the shaft sealing element preferably has the shape of a circular ring. The shaft sealing element preferably rests circumferentially against a lateral surface of the drive shaft.

[0014] According to a further development of the invention, the shaft sealing element comprises a first hollow-circular-cylindrical component and a second hollow-circular-cylindrical component, which are integrally formed as a coherent unit and each completely enclose the drive shaft. In particular, the first component of the shaft sealing element, forming the sealing surface as a sealing lip, is arranged circumferentially, preferably completely, against the outer surface of the drive shaft.

[0015] A gap, in particular a gap with a uniform width in both a circumferential direction and an axial direction, and thus an annular gap, is advantageously formed between an inner circumferential surface of the second component of the shaft sealing element and the circumferential surface of the drive shaft. The width is related to an extension in the radial direction. In a two-part embodiment of the shaft sealing element formed in this way from a first hollow circular cylindrical component and a second hollow circular cylindrical component, the through opening is widened in the region of the second component of the shaft sealing element by the gap formed between the inner circumferential surface of the second component and the circumferential surface of the drive shaft.

[0016] According to a first alternative embodiment of the invention, the outer surface of the drive shaft has at least one recess. The preferably groove-shaped recess is designed as a through-opening, extending in the axial direction. The extent of the recess in the axial direction is greater than the extent of the shaft sealing element in the axial direction. Furthermore, the shaft sealing element is arranged adjacent to the recess on the outer surface of the drive shaft in such a way that the recess in the outer surface of the drive shaft projects beyond the shaft sealing element on both sides in the axial direction. The recess in the outer surface of the drive shaft projects from the shaft sealing element on both sides in the axial direction.

[0017] The cross section of the through-opening arranged in a plane spanned perpendicular to the axial direction is enclosed at least in regions by boundary edges of the recess on the one hand and a section of the inner circumferential surface of the shaft sealing element on the other hand.

[0018] In a preferred embodiment of the lateral surface of the drive shaft with at least two recesses, the recesses are arranged evenly distributed over the circumference of the lateral surface of the drive shaft.

[0019] According to a second alternative embodiment of the invention, an inner surface of the shaft sealing element, which surface rests against the surface of the drive shaft, has at least one contour for forming at least one through-opening.

[0020] The at least one contour can be designed in the form of a groove extending in an axial direction. The cross-section of the through-opening, arranged in the plane spanned perpendicular to the axial direction, is enclosed by boundary edges of the contour provided within the shaft sealing element, on the one hand, and a portion of the lateral surface of the drive shaft, on the other.

[0021] Both in the design of the lateral surface of the drive shaft with the at least one, in particular groove-shaped recess and in the design of the inner lateral surface of the shaft sealing element lying against the lateral surface of the drive shaft with the at least one, likewise in particular groove-shaped contour, the respective through-opening preferably has a substantially rectangular cross-section or a substantially semicircular cross-section in the plane oriented perpendicular to the axial direction, neglecting the curved lateral surfaces of the drive shaft or the shaft sealing element.

[0022] On the other hand, the at least one contour provided on the inner surface of the shaft sealing element, which is in contact with the surface of the drive shaft, can be designed in the form of a through opening, in particular with a circular cross-section.

[0023] In an advantageous design of the inner circumferential surface of the shaft sealing element with at least two contours, the contours are arranged evenly distributed over the circumference of the circumferential surface of the shaft sealing element.

[0024] According to a further development of the invention, the device comprises a first expansion device for expanding the gaseous fluid acting on the counterpressure region from a level of an intermediate pressure p z to a level of low pressure p N within the intake area and a second expansion device for expanding the gaseous fluid from a level of high pressure p H to the level of the intermediate pressure p Z within the backpressure range, as well as a regulating device or a control device. The through-opening is preferably designed as a first expansion device, while the second expansion device is preferably designed as a control valve.

[0025] The device according to the invention for compressing a gaseous fluid, in particular as a further development of a scroll compressor with preferably electric drive, with the shaft sealing element arranged between the drive shaft and the wall for sealing the counterpressure area of the intake area with defined leakage, has in summary further various advantages: - small number of individual components and their simple assembly result in only minimal assembly effort and minimal assembly costs, - optimal lubrication of the shaft sealing element and the drive shaft results in only minimal friction and minimal wear, especially in the area of the sealing surfaces, thereby - trouble-free operation with maximum device life and minimal operating costs.

[0026] Further details, features, and advantages of embodiments of the invention will become apparent from the following description of exemplary embodiments with reference to the accompanying drawings. They show: Fig. 1: Section of a compression mechanism of a device for compressing a gaseous fluid, in particular a scroll compressor, in a lateral sectional view, Fig. 2a: Section of the compression mechanism of a scroll compressor from the state of the art with integrated expansion devices in a lateral sectional view, Fig. 2b to 2d: alternative designs of expansion devices of the compression mechanism of a scroll compressor from the prior art, each in a lateral sectional view, Fig. 2e: a sliding element with expansion function arranged on a wall of a housing between the wall and a movable orbiter of the compression mechanism, Fig. 3a: a first embodiment of a drive shaft-housing connection with an intermediately mounted shaft sealing element and a sealing surface with a through-opening, in particular a drive shaft with a recess, in a perspective detailed view, Fig. 3b: a second embodiment of a drive shaft-housing connection with an intermediately mounted shaft sealing element and a sealing surface with a through-opening, in particular a shaft sealing element with a recess, in a perspective detailed view, Fig. 3c: an alternative second embodiment of a drive shaft-housing connection in a perspective detailed view, Fig. 4a to 4d: each show a drive shaft of a first embodiment of a drive shaft-housing connection according to Fig. 3a compared to a drive shaft of a scroll compressor from the state of the art and Fig. 5a to 5e: each a shaft sealing element of a second embodiment of a drive shaft-housing connection according to Fig. 3b in comparison to a shaft sealing element of a scroll compressor from the state of the art.

[0027] Out of Fig. 1 shows a section of a compression mechanism of a device 1 for compressing a gaseous fluid, in particular a scroll compressor 1, in a lateral sectional view. The scroll compressor 1 comprises a housing 2, a stationary, fixed stator 3 with a disc-shaped base plate 3a and a spiral-shaped wall 3b extending from one side of the base plate 3a, and a movable orbiter 4 with a disc-shaped base plate 4a and a spiral-shaped wall 4b extending from a front side of the base plate 4a. The stator 3 and orbiter 4, which are also referred to as the stationary or fixed scroll 3 and the movable scroll 4, respectively, interact. The base plates 3a, 4a are arranged relative to one another such that the wall 3b of the stator 3 and the wall 4b of the orbiter 4 interlock.

[0028] The movable spiral 4 is moved along a circular path by means of an eccentric drive. As the spiral 4 moves, the walls 3b, 4b touch each other at several points and form several consecutive, enclosed working chambers 5 within the walls 3b, 4b, with adjacent working chambers 5 defining volumes of different sizes. In response to the counter-rotating movement of the two nested, spiral-shaped walls 3b, 4b, in particular to the movement of the orbiter 4, the volumes and positions of the working chambers 5 are changed. The volumes of the working chambers 5 become increasingly smaller towards the middle or center of the spiral-shaped walls 3b, 4b, which are also referred to as spiral walls. The gaseous fluid to be compressed, in particular a refrigerant, which acts on the working chambers, is compressed and expelled from the scroll compressor via an outlet.

[0029] The eccentric drive consists of a drive shaft 6, which rotates about a rotational axis 7, and an intermediate element 8. The drive shaft 6 is supported on the housing 2 via a first bearing 9, in particular a ball bearing. The orbiter 4 is eccentrically connected to the drive shaft 6 via the intermediate element 8, with the axes of the orbiter 4 and the drive shaft 6 being offset from one another. The orbiter 4 is supported on the intermediate element 8 via a second bearing 10.

[0030] The scroll compressor 1 also has a guide device 11, which prevents rotation of the movable scroll 4 and enables the movable scroll 4 to orbit. The guide device 11 usually comprises a plurality of circular openings 11-1 arranged adjacent to one another at specific intervals. The openings 11-1, which are preferably designed as blind bores, are formed in a rear side of the base plate 4a of the movable scroll 4.

[0031] Furthermore, the guide device 11 has pins 11-2, which are formed protruding from a wall 12 of the housing 2 and each engages an opening 11-1 formed in the base plate 4a of the movable spiral 4. The pins 11-2 protrude from the wall 12 with a first end, while a second end is arranged in the wall 12 of the housing 2.

[0032] Arranged within the housing 2 is a wall 12, also referred to as the counter wall 12, which is fixed to the housing 2. A counter pressure area 13 is formed between the counter wall 12 and the movable scroll 4. The wall 12 delimits the counter pressure area 13 formed between the orbiter 4 and the housing 2 and also forms a partition between the counter pressure area 13 and an intake area 14. The counter pressure area 13 is formed on the rear side of the base plate 4a of the movable scroll 4, relative to the spiral walls 4b.

[0033] Due to the counterpressure prevailing within the counterpressure area 13, the movable spiral 4 is pressed against the fixed spiral 3 fixed to the housing 2 with a force acting in the axial direction. The pressure force acting in the axial direction as a result of the counterpressure per area applied to the rear side of the disc-shaped base plate 4a of the movable spiral 4 is controlled or regulated by the counterpressure or contact pressure. The level of the contact pressure is an intermediate pressure p Z or mean pressure between the levels of high pressure p H and the low pressure p N as discharge pressure and suction pressure of the compressor.

[0034] To seal the counterpressure area 13 and the intake area 14 from each other as two pressure chambers subjected to different pressures, a shaft sealing element 15 is arranged, particularly in the area of the first bearing 9, between the drive shaft 6 and the counter wall 12. Furthermore, an annular, particularly circular, orbiter sealing element 16 is provided between the movable spiral 4 and the counter wall 12, which orbiter sealing element rests against a plate-shaped sliding element 12a arranged on the surface of the counter wall 12 facing the movable spiral 4.

[0035] To reduce frictional heat generated during the movement of the spiral walls 3b, 4b towards each other and of the spiral wall 4b of the orbiter 4 towards the counter wall 12 and to improve the seals between the boundary surfaces of the working chambers 5 and between the counterpressure region 13 and the suction region 14, a lubricant, in particular an oil, is added to the fluid.

[0036] In Fig. 2a shows a section of the compression mechanism of a scroll compressor from the prior art with integrated expansion devices 17, 18 in a lateral sectional view, while from the Fig. 2b to 2d show alternative designs of expansion devices 17, 18 of different backpressure systems of scroll compressors from the prior art, each in a lateral sectional view.

[0037] The back pressure systems of conventional scroll compressors have a first expansion device 17 for expanding the refrigerant from the level of the back pressure or the intermediate pressure p Z to the level of low pressure p N and a second expansion device 18 for expanding the refrigerant from the high pressure level p H to the level of the intermediate pressure p Z each in combination with a control device or a regulating device.

[0038] The counterpressure system according to Fig. 2a, for example, has a first expansion device 17 configured as a nozzle and arranged in a flow channel 19, while a control valve serves as the second expansion device 18. A filter element 20 is provided at the inlet to the flow channel 19 to prevent any particles present, for example, which have become detached from the shaft sealing element 15, which is subject to wear on the drive shaft 6, from clogging the flow channel 19, in particular the inlet of the flow channel 19.

[0039] With the counterpressure system according to Fig. 2b, both the first expansion device 17 and the second expansion device 18 are arranged within a flow channel 19 connecting the low-pressure region and the high-pressure region. A space formed between the expansion devices 17, 18 is hydraulically connected to the counterpressure region 13 via a connecting channel 21.

[0040] In the Fig. 2c and Fig. 2d shows a counterpressure system with a flow channel 22 formed within the drive shaft 6a, which extends between the end of the drive shaft 6a directed towards the movable spiral 4 and thus the counterpressure area 13 and the intake area, coaxial to the rotational axis 7 of the drive shaft 6a. In the counterpressure system according to Fig. 2c, the first expansion device 17, which is designed in particular as a nozzle, is arranged within the flow channel 22 connecting the counterpressure region 13 and the low-pressure region, while in the counterpressure system according to Fig. 2d, the first expansion device 17 is formed in the region of the second bearing 10 as a through-bore oriented transversely to the rotational axis 7 of the drive shaft 6a and thus in the radial direction, in combination with a recess in the drive shaft 6a. The flow channel 22 is closed in the axial direction in the region of the second bearing 10. The recess in the drive shaft 6a and an inner ring of the second bearing 10 define a flow channel that is connected to the intake area. The through-bore represents a connection between the flow channel 22 formed within the drive shaft 6a and the flow channel defined by the recess in the drive shaft 6a, which is in the form of a groove or notch and extends in the axial direction, and the inner ring of the second bearing 10.

[0041] Out of Fig. 2e shows a sliding element 12a with an expansion function arranged on the wall 12 of the housing 2 between the wall 12 and the movable orbiter 4 of the compression mechanism. The plate-shaped sliding element 12a with a circumferentially extending channel serves as a first expansion device 17 for expanding the refrigerant from the level of the back pressure or the intermediate pressure p Z to the level of low pressure p N trained.

[0042] In a controlled backpressure system, the first expansion device 17 must be designed to function very precisely, since its accuracy has a decisive influence on the value of the intermediate pressure p ZIn addition, all sealing elements 15, 16 of the backpressure region 13, in particular the shaft sealing element 15, are designed to ensure maximum tightness in order to prevent the leakage rate of the refrigerant from the backpressure region 13 into the intake region 14 or the low-pressure region, as well as to prevent an overflow of the refrigerant from the high-pressure region into the backpressure region 13 and thus to define the backpressure exclusively by means of the first expansion device 17.

[0043] Compared to the controlled backpressure system, the accuracy of the first expansion device 17 is less significant in a controlled backpressure system, since the value of the intermediate pressure p Z within the back pressure area 13 is defined by the second expansion device 18, which is designed, for example, as a control valve.

[0044] In the Fig. 3a to 3c show a first embodiment and two alternative second embodiments of a drive shaft-housing connection, each with an intermediately mounted shaft sealing element 15a, 15b, 15c and a sealing surface 23 formed between the drive shaft 6a, 6b and the shaft sealing element 15a, 15b, 15c with a through opening 24a, 24b, 24c in a perspective detailed view.

[0045] The through-opening 24a, 24b, 24c is designed as a first expansion device 17 for expanding the refrigerant from the level of the back pressure or the intermediate pressure p Z to the level of low pressure p Ndesigned such that, in the area of the drive shaft-housing connection with the intermediately mounted shaft sealing element 15a, 15b, 15c, a defined leakage mass flow of the refrigerant flows from the backpressure area 13 into the intake area 14. Since a lubricant, in particular an oil, is mixed with the refrigerant, the sealing surface 23 is exposed to lubricant and thus lubricated.

[0046] The annular shaft sealing element 15a, 15b, 15c each comprises a first hollow circular cylindrical component 15-1a, 15-1b, 15-1c and a second hollow circular cylindrical component 15-2, which are integrally formed as a coherent unit and each completely enclose the circular cylindrical drive shaft 6a, 6b. With an outer circumferential surface, the components 15-1a, 15-1b, 15-1c, 15-2 each bear tightly against an inner surface of a preferably circular opening in the wall 12.

[0047] Between the inner circumferential surface of the second component 15-2 of the shaft sealing element 15a, 15b, 15c and the surface, in particular the circumferential surface of the drive shaft 6a, 6b, a gap of uniform width is formed in both the circumferential and axial directions, while the first component 15-1a, 15-1b, 15-1c of the shaft sealing element 15a, 15b, 15c is designed as a sealing lip, circumferentially abutting the surface of the drive shaft 6a, 6b for sealing the counterpressure region 13 from the intake region 14. In the assembled state of the device, the inner circumferential surface of the first component 15-1a, 15-1b, 15-1c of the shaft sealing element 15a, 15b, 15c has, on the one hand, a diameter that corresponds to the outer diameter of the surface of the drive shaft 6a, 6b.On the other hand, the diameter of the inner circumferential surface of the first component 15-1a, 15-1b, 15-1c in the unassembled state of the device is smaller than the outer diameter of the surface of the drive shaft 6a, 6b in order to ensure the required tightness when elastically deformed in the assembled state.

[0048] As in Fig. As shown in Figure 3a, the first embodiment of the drive shaft-housing connection has a shaft sealing element 15a mounted between the housing 2, in particular the wall 12, and the drive shaft 6b. The first component 15-1a of the shaft sealing element 15a, designed as a sealing lip, rests essentially over its entire circumference against the outer surface of the drive shaft 6b.

[0049] The surface of the drive shaft 6b has a recess 60, which extends in the axial direction in the form of a shallow groove or notch with a constant width and constant depth. The width of the recess 60 refers to the circumferential extent, while the depth extends in the radial direction of the drive shaft 6b.

[0050] In the axial direction, the recess 60 has such an extension, also referred to as length, that the recess 60 projects beyond the shaft sealing element 15a on both sides, so that a through-opening 24a is formed in the region of the recess 60, which hydraulically connects the counterpressure region 13 and the intake region 14. The length of the recess 60 is preferably greater than the width of the recess 60, which in turn is greater than the depth of the recess 60.

[0051] In the region of the first component 15-1a of the shaft sealing element 15a, the through-opening 24a has a substantially rectangular, free cross-section in a plane oriented perpendicular to the axial direction, which is delimited on an underside by a base of the recess 60 and on an upper side opposite the underside by the shaft sealing element 15a. Since the recess 60 protrudes in the axial direction, on the one hand, from the first component 15-1a of the shaft sealing element 15a, extending into the counterpressure region 13, and on the other hand, from the second component 15-2 of the shaft sealing element 15a, extending into the intake region 14, the counterpressure region 13 and the intake region 14 are connected to one another via the through-opening 24a.

[0052] In the area of the second component 15-2 of the shaft sealing element 15a, the through opening 24a is widened by the gap formed between the inner circumferential surface of the second component 15-2 of the shaft sealing element 15a and the surface of the drive shaft 6b.

[0053] The second embodiments of the drive shaft-housing connection are, according to the Fig. 3b and Fig. 3c, each also formed with a shaft sealing element 15b, 15c mounted between the housing 2, in particular the wall 12, and a conventional drive shaft 6a. The second component 15-2 of the shaft sealing element 15a of the first embodiment according to Fig. 3a and the second component 15-2 of the shaft sealing element 15b, 15c of the second embodiments are identical.

[0054] The first component 15-1b of the shaft sealing element 15b of the second embodiment according to Fig. 3b has a contour 150b on the inner lateral surface aligned with the surface of the drive shaft 6a, in particular a recess extending in the axial direction in the form of a shallow groove or a shallow notch with a substantially constant width. The width of the contour 150b is again understood to mean its extent in the circumferential direction. While the depth of the recess is constant in the axial direction, the depth of the recess can vary in the circumferential direction, in particular becoming steadily smaller towards one edge of the recess.

[0055] In the axial direction, the contour 150b extends through the entire first component 15-1b of the shaft sealing element 15b, so that a through-opening 24b is formed in the region of the shaft sealing element 15b, which hydraulically connects the counterpressure region 13 to the intake region 14. The width of the contour 150b is preferably greater than the depth of the contour 150b, which extends radially into the first component 15-1b of the shaft sealing element 15b. The first component 15-1b of the shaft sealing element 15b, designed as a sealing lip, bears completely against the outer surface of the drive shaft 6a, except in the region of the contour 150b designed as a recess.

[0056] The through-opening 24b has, in the region of the first component 15-1b of the shaft sealing element 15b, in a plane oriented perpendicular to the axial direction, a substantially rectangular or semicircular, free cross-section which is delimited on a lower side by the surface of the drive shaft 6a and on an upper side opposite the lower side or the side surfaces by the first component 15-1b of the shaft sealing element 15b. In the area of the second component 15-2 of the shaft sealing element 15b, the through opening 24b corresponds to the gap formed between the inner circumferential surface of the second component 15-2 of the shaft sealing element 15b and the surface of the drive shaft 6a.

[0057] The first component 15-1c of the shaft sealing element 15c of the alternative second embodiment according to Fig. 3c has a contour 150c on the inner surface aligned with the surface of the drive shaft 6a, in particular a recess in the form of a through-opening with a circular cross-section. The contour 150c extends through the first component 15-1c of the shaft sealing element 15c, so that a through-opening 24c is formed in the region of the shaft sealing element 15c, which hydraulically connects the counterpressure region 13 to the intake region 14. The first component 15-1c of the shaft sealing element 15c, designed as a sealing lip, bears completely against the outer surface of the drive shaft 6a. The through-opening 24c is completely delimited by the first component 15-1c of the shaft sealing element 15c.

[0058] In the area of the second component 15-2 of the shaft sealing element 15c, the through opening 24c again corresponds to the gap formed between the inner circumferential surface of the second component 15-2 of the shaft sealing element 15c and the surface of the drive shaft 6a.

[0059] The outlet of the counterpressure region 13, designed as a through-opening 24a, 24b, 24c, is arranged at the level of the rotational axis 7 of the drive shaft 6, 6a, 6b and thus preferably centrally within the counterpressure region 13. Since the fill level of the lubricant, in particular the oil, reaches the level of the through-opening 24a, 24b, 24c at least when the device 1 or the orbiter 4 is at a standstill or when operating at minimum speeds, it is ensured that the oil flows through the defined through-opening 24a, 24b, 24c as a leakage path to the intake region 14 and thereby lubricates and cools at least the first component 15-1a, 15-1b, 15-1c of the shaft sealing element 15a, 15b, 15c, designed as a sealing lip. In addition, the lubrication of bearings 9, 10 is improved.

[0060] Since the back pressure or the intermediate pressure prevailing in the back pressure region 13 is regulated via a second expansion device 18 designed as a control valve, no requirements are placed on a high accuracy of the through opening 24a, 24b, 24c as the first expansion device 17.

[0061] In addition, the device 1 can be used without a filter element 20, according to Fig. 2a, since the centrifugal force generated during operation upon rotation of the drive shaft 6, 6a, 6b and the elements moved with the drive shaft 6, 6a, 6b transports any unwanted particles present radially outwards and thus cannot clog the through-opening 24a, 24b, 24c. If particles accumulate in front of the through-opening 24a, 24b, 24c when the device 1 is at a standstill, such as during pressure equalization during a compressor stop, the particles are removed in the manner mentioned after the device 1 is started up as a result of the rotation of the drive shaft 6, 6a, 6b.

[0062] From the Fig. 4a to 4d each show a drive shaft 6b-1, 6b-2, 6b-3 of a first embodiment of a drive shaft-housing connection according to Fig. 3a with at least one recess 60-1, 60-2 compared to a drive shaft 6a of a scroll compressor without a recess. The groove-shaped recesses 60-1, 60-2 have essentially the same dimensions in the axial direction.

[0063] The recesses 60-1, 60-2 provided within the drive shafts 6b-1, 6b-2 from the Fig. 4b and Fig. 4c differ in both the size and shape of the cross-section formed in the plane oriented perpendicular to the axial direction. While the cross-section of recess 60-1 is rectangular, the cross-section of recess 60-2 is semicircular. Recess 60-1 is significantly wider than recess 60-2. Recesses 60-1, 60-2 can also have different depths, in particular in the range from 0.01 mm to 0.3 mm.

[0064] Compared to the embodiments of the drive shafts 6b-1, 6b-2 from the Fig. 4b and Fig. 4c are in the embodiment of the drive shaft 6b-3, according to Fig. 4d, a plurality of recesses 60-2 are provided. The recesses 60-2 are preferably distributed evenly over the circumference of the surface of the drive shaft 6b-3 and can be aligned with one another in the axial direction. Alternatively, the recesses are arranged with different lengths and, if appropriate, offset from one another in the axial direction. The length of the recess 60, 60-1, 60-2 extending in the axial direction ensures that a corresponding expansion cross-section is formed in conjunction with the first component 15-1a and the second component 15-2 of the shaft sealing element 15a.

[0065] In the Fig. 5a to 5e is a shaft sealing element 15b-1, 15b-2, 15b-3, 15b-4 of a second embodiment of a drive shaft-housing connection according to Fig. 3b shows a shaft sealing element 15a of a scroll compressor without a contour from the prior art, with at least one contour 150b-1, 150b-2. The contours 150b-1, 150b-2, each designed as a groove-shaped recess, have essentially the same dimensions in the circumferential direction, at least in the region of the inner diameter of the shaft sealing element 15b-1, 15b-2, 15b-3, 15b-4.

[0066] The contours 150b-1, 150b-2 provided on the inner surface of the shaft sealing element 15b-1, 15b-2 from the Fig. 5b and Fig. 5c differ in both the size and shape of the cross-section formed in the plane oriented perpendicular to the axial direction. While the cross-section of contour 150b-1 is rectangular, the cross-section of recess 150b-2 is semicircular. Contour 150b-1 is significantly wider than contour 150b-2 in the area of the outer radius due to the basic shape of the cross-section. Contours 150b-1, 150b-2 can also have different depths, in particular in the range from 0.01 mm to 0.3 mm.

[0067] In comparison to the embodiments of the shaft sealing elements 15b-1, 15b-2 from the Fig. 5b and Fig. 5c are in the embodiments of the shaft sealing elements 15b-3, 15b-4, according to the Fig. 5d and Fig.5e, a plurality of contours 150b-2, in particular three or four, are provided. The contours 150b-2 are preferably distributed evenly over the circumference of the inner circumferential surface of the shaft sealing element 15b-3, 15b-4. The cross-section of the contours can be rectangular or semicircular. List of reference symbols 1 scroll compressor, device 2 housings 3 Stator, fixed spiral 3a Base plate fixed spiral 3 3b Wall fixed spiral 3 4 Orbiter, movable spiral 4a Base plate movable spiral 4 4b Wall of movable spiral 4 5 Workspace 6,6a,6b,6b-1,6b-2,6b-3 drive shaft 60, 60-1, 60-2 drive shaft recess 7 Rotation axis 8 Intermediate element with additional weight 9 first camp 10 second camp 11 Guide device 11-1 Opening 11-2 pin 12 Wall, counter wall 12a Sliding element 13 Backpressure area, backpressure chamber 14 Intake area 15,15a,15b, 15b-1, 15b-2, 15b-3, 15b-4,15c Shaft sealing element 15-1a, 15-1b, 15-1c first component shaft sealing element 15-2 second component shaft sealing element 150b, 150b-1, 150b-2, 150c contour shaft sealing element 16 Orbiter sealing element 17 first expansion device 18 second expansion device 19 Flow channel 20 filter element 21 connecting channel 22 flow channel 23 Sealing surface 24a, 24b, 24c Through opening sealing surface 23 p H High pressure p N Low pressure p Z Intermediate pressure, contact pressure

Claims

[1] Device (1) for compressing a gaseous fluid, in particular a scroll compressor, comprising a housing (2) with a wall (12) and a compression mechanism with a stationary stator (3) and a movable orbiter (4) which is driven via a drive shaft (6, 6a, 6b, 6b-1, 6b-2, 6b-3), wherein - the wall (12) and the orbiter (4) are designed to at least partially enclose a counterpressure region (13) and the wall (12) is designed between the counterpressure region (13) and a suction region (14), delimiting the counterpressure region (13) from the suction region (14), - the drive shaft (6, 6a, 6b, 6b-1, 6b-2, 6b-3) is arranged so as to protrude through an opening formed within the wall (12), wherein a shaft sealing element (15, 15a, 15b, 15b-1, 15b-2, 15b-3, 15b-4, 15c) is arranged between the drive shaft (6, 6a, 6b, 6b-1, 6b-2, 6b-3) and the wall (12) for sealing the counterpressure region (13) from the intake region (14), wherein between the drive shaft (6, 6a, 6b, 6b-1, 6b-2, 6b-3) and the shaft sealing element (15, 15a, 15b, 15b-1, 15b-2, 15b-3, 15b-4, 15c) a sealing surface (23) is formed with a through opening (24a, 24b, 24c) interrupting the sealing surface (23) and hydraulically connecting the counterpressure region (13) and the suction region (14). [2] Device (1) according to claim 1, characterized by that the drive shaft (6, 6a, 6b, 6b-1, 6b-2, 6b-3) is circular-cylindrical. [3] Device (1) according to claim 1 or 2, characterized bythat the shaft sealing element (15, 15a, 15b, 15c, 15b-1, 15b-2, 15b-3, 15b-4) is circular in shape. [4] Device (1) according to claim 3, characterized by that the shaft sealing element (15, 15a, 15b, 15c, 15b-1, 15b-2, 15b-3, 15b-4) is arranged circumferentially against a lateral surface of the drive shaft (6, 6a, 6b, 6b-1, 6b-2, 6b-3). [5] Device (1) according to claim 3 or 4, characterized by that the shaft sealing element (15, 15a, 15b, 15c, 15b-1, 15b-2, 15b-3, 15b-4) has a first hollow circular cylindrical component (15-1a, 15-1b, 15-1c) and a second hollow circular cylindrical component (15-2), which are formed integrally as a coherent unit and each completely enclose the drive shaft (6, 6a, 6b, 6b-1, 6b-2, 6b-3). [6] Device (1) according to claim 5, characterized bythat the first component (15-1a, 15-1b, 15-1c) of the shaft sealing element (15, 15a, 15b, 15c, 15b-1, 15b-2, 15b-3, 15b-4) is arranged circumferentially adjacent to a lateral surface of the drive shaft (6, 6a, 6b, 6b-1, 6b-2, 6b-3) so as to form the sealing surface (23). [7] Device (1) according to claim 5 or 6, characterized by that a gap is formed between an inner circumferential surface of the second component (15-2) of the shaft sealing element (15, 15a, 15b, 15c, 15b-1, 15b-2, 15b-3, 15b-4) and a circumferential surface of the drive shaft (6, 6a, 6b, 6b-1, 6b-2, 6b-3). [8] Device (1) according to one of claims 4 to 7, characterized bythat the outer surface of the drive shaft (6b, 6b-1, 6b-2, 6b-3) has at least one recess (60, 60-1, 60-2) which is designed as a through-opening (24a) in the form of a groove extending in an axial direction, wherein an extension of the recess (60, 60-1, 60-2) in the axial direction is greater than an extension of the shaft sealing element (15a) in the axial direction and the shaft sealing element (15a) is aligned with the recess (60, 60-1, 60-2) in such a way that it abuts the outer surface of the drive shaft (6b, 6b-1, 6b-2, 6b-3) in such a way that the recess (60, 60-1, 60-2) in the axial direction on both sides of the shaft sealing element (15a) surmounted. [9] Device (1) according to claim 8, characterized by that at least two recesses (60-2) are formed which are arranged uniformly distributed over the circumference of the lateral surface of the drive shaft (6b, 6b-3). [10] Device (1) according to one of claims 4 to 7, characterized bythat an inner surface of the shaft sealing element (15b, 15b-1, 15b-2, 15b-3, 15b-4, 15c) lying against the surface of the drive shaft (6, 6a) has at least one contour (150b, 150b-1, 150b-2, 150c) for forming at least one through opening (24b, 24c). [11] Device (1) according to claim 10, characterized by that the at least one contour (150b, 150b-1, 150b-2) is designed in the form of a groove extending in an axial direction. [12] Device (1) according to one of claims 1 to 11, characterized by that the through opening (24a, 24b) has a substantially rectangular cross-section or a substantially semicircular cross-section in a plane oriented perpendicular to an axial direction. [13] Device (1) according to claim 10, characterized by that the at least one contour (150c) is designed in the form of a through opening (24c), in particular with a circular cross-section. [14] Device (1) according to one of claims 10 to 13, characterized by that at least two contours (150b, 150b-1, 150b-2) are formed, which are arranged uniformly distributed over the circumference of the lateral surface of the shaft sealing element (15b, 15b-1, 15b-2, 15b-3, 15b-4). [15] Device (1) according to one of claims 1 to 14, characterized by that a first expansion device (17) for expanding the gaseous fluid acting on the counterpressure region (13) from a level of an intermediate pressure p Z to a level of low pressure p N within the intake area (14) and a second expansion device (18) for expanding the gaseous fluid from a level of high pressure p H to the level of the intermediate pressure p Z within the back pressure area (13) and a regulating device or a control device are formed. [16] Device (1) according to claim 15, characterized bythat the through opening (24a, 24b, 24c) is designed as a first expansion device (17). [17] Device (1) according to claim 15 or 16, characterized by that the second expansion device (18) is designed as a control valve.

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