Intermediate Cover of a Filter Housing of a Filter for Purifying Liquid Fluids and Filter Insert, Filter and Use

Abstract

An intermediate cover of a filter housing of a filter for purifying liquids can be mounted in the filter housing for separating a filter receiving space for a filter insert from a centrifuge receiving space for a centrifuge separator by a rotary and/or insertion movement relative to an imaginary axis. The intermediate cover is provided with a portion of at least one clean fluid channel forming a fluidic connection between a clean fluid side of the filter insert and a fluid outlet of the filter housing for a purified clean fluid. The filter insert has a connecting device arranged at an axial end face and connectable to the intermediate cover. An outlet opening for purified clean fluid is arranged at the axial end face and corresponds with an inlet opening of the clean fluid channel of the intermediate cover. The outlet opening at least partially forms the connecting device.

Claims

1. An intermediate cover of a filter housing of a filter for purifying liquid fluids, wherein the intermediate cover is configured to be mounted in an interior of the filter housing for separation of a filter receiving space for at least one filter insert from a centrifuge receiving space for at least one centrifuge separator by a rotary and/or insertion movement relative to an axis; the intermediate cover comprising at least a portion of at least one clean fluid channel configured to form a first fluidic connection between a clean fluid side of the at least one filter insert and at least one fluid outlet of the filter housing for a purified clean fluid.

2. The intermediate cover according to claim 1, further comprising at least one raw fluid channel configured to form a second fluidic connection between at least one fluid inlet of the filter housing for a raw fluid to be purified and at least one centrifuge inlet of the at least one centrifuge separator.

3. The intermediate cover according to claim 2, further comprising a filter-side end face facing the filter receiving space and a centrifuge-side end face facing the centrifuge receiving space, wherein the at least one raw fluid channel connects the filter-side end face with the centrifuge-side end face.

4. The intermediate cover according to claim 2, wherein a plurality of the at least one raw fluid channel are arranged circumferentially distributed in respect to the axis.

5. The intermediate cover according to claim 1, further comprising an axial end face, axial in respect to the axis and facing the at least one filter insert, wherein at least one inlet opening connected to the at least one clean fluid channel is arranged at the axial end face, wherein the at least one inlet opening corresponds with at least one outlet opening of the at least one filter insert for the purified clean fluid when the intermediate cover is mounted in the interior of the filter housing.

6. The intermediate cover according to claim 1, further comprising at least one circumferential side, circumferentially extending in respect to the axis, wherein at least one outlet opening of the at least one clean fluid channel is arranged at the at least one circumferential side, wherein the at least one outlet opening of the at least one clean fluid channel corresponds with the at least one fluid outlet of the filter housing for the purified clean fluid when the intermediate cover is mounted in the interior of the filter housing.

7. The intermediate cover according to claim 6, wherein the least one outlet opening of the at least one clean fluid channel extends across an entire outer circumference of the intermediate cover.

8. The intermediate cover according to claim 1, further comprising a filter-side separation section facing the filter receiving space and a centrifuge-side separation section facing the centrifuge receiving space, wherein the at least one clean fluid channel extends axially in respect to the axis between the filter-side separation section and the centrifuge-side separation section.

9. The intermediate cover according to claim 8, further comprising at least one raw fluid channel configured to form a second fluidic connection between at least one fluid inlet of the filter housing for a raw fluid to be purified and at least one centrifuge inlet of the at least one centrifuge separator, wherein the at least one raw fluid channel passes axially in respect to the axis through an intermediate space between the filter-side separation section and the centrifuge-side separation section, wherein the intermediate space forms at least partially the at least one clean fluid channel, wherein the at least one raw fluid channel is surrounded in the intermediate space by at least one channel wall.

10. The intermediate cover according to claim 1, further comprising a radially outer circumferential side in respect to the axis and at least one circumferentially continuous seal arranged at the radially outer circumferential side.

11. The intermediate cover according to claim 1, further comprising a radially outer circumferential side in respect to the axis and two circumferentially continuous seals arranged at the radially outer circumferential side, wherein the two circumferentially continuous seals are axially spaced apart from each other, wherein axially between the two circumferentially continuous seals at least one outlet opening of the at least one clean fluid channel extends out of the radially outer circumferential side.

12. The intermediate cover according to claim 1, further comprising a filter-side end face facing the filter receiving space and a centrifuge-side end face facing the centrifuge receiving space, wherein the centrifuge-side end face comprises at least one centrifuge-centering device for securing on the at least one centrifuge separator and/or the filter-side end face comprises at least one filter centering device for securing on the at least one filter insert.

13. The intermediate cover according to claim 1, further comprising a cup-shaped centrifuge-side end face facing the centrifuge receiving space and/or a cup-shaped filter-side end face facing the filter receiving space.

14. A filter insert for exchangeable installation in a filter housing of a filter for cleaning liquid fluids, wherein the filter insert is configured to be mounted in the filter housing and removed from the filter housing by a rotary and/or insertion movement in respect to an axis, the filter insert comprising: at least one connecting device, arranged at a first axial end face that is axial in respect to the axis, wherein the at least one connecting device is configured to connect to an intermediate cover configured to be arranged in an interior of the filter housing for separation of a filter receiving space for the filter insert from a centrifuge receiving space for at least one centrifuge separator; at least one outlet opening for purified clean fluid arranged at the first axial end face, wherein the at least one outlet opening is configured to correspond with at least one inlet opening of at least one clean fluid channel of the intermediate cover, wherein the at least one outlet opening at least partially forms the at least one connecting device.

15. The filter insert according to claim 14, further comprising at least one part of a sealing device configured to seal the at least one outlet opening against the intermediate cover.

16. The filter insert according to claim 14, further comprising a second axial end facing axially away from the at least one connecting device, wherein the second axial end face comprises at least one part of an actuation device configured to actuate a fluid drain of the filter housing.

17. The filter insert according to claim 14, wherein the at least one clean fluid channel of the intermediate cover forms at least partially a fluidic connection between a clean fluid side of the at least one filter insert and at least one fluid outlet of the filter housing for a purified clean fluid.

18. A delivery unit comprising: a filter insert for exchangeable installation in a filter housing of a filter for cleaning liquid fluids, wherein the filter insert is configured to be mounted in the filter housing and removed from the filter housing by a rotary and/or insertion movement in respect to an axis; an intermediate cover configured to be arranged in an interior of the filter housing for separation of a filter receiving space for the filter insert from a centrifuge receiving space for at least one centrifuge separator and configured to be mounted in the filter housing and removed from the filter housing by a rotary and/or insertion movement in respect to the axis; wherein the intermediate cover comprises at least a portion of at least one clean fluid channel configured to form a fluidic connection between a clean fluid side of the filter insert and at least one fluid outlet of the filter housing for a purified clean fluid, wherein the at least one clean fluid channel comprises at least one inlet opening; wherein the filter insert comprises at least one connecting device, arranged at a first axial end face, axial in respect to the axis, of the filter insert, wherein the at least one connecting device of the filter insert is configured to connect to the intermediate cover; wherein the filter insert comprises at least one outlet opening for purified clean fluid arranged at the first axial end face of the filter insert, wherein the at least one outlet opening of the filter insert is configured to correspond to the at least one inlet opening of the at least one clean fluid channel of the intermediate cover; wherein the at least one outlet opening of the filter insert at least partially forms the at least one connecting device of the filter insert.

19. A filter comprising: a filter housing comprising a housing cup; a filter insert inserted in the housing cup of the filter housing, the filter insert configured to be mounted in the filter housing and removed from the filter housing by a rotary and/or insertion movement in respect to an axis; an intermediate cover inserted in the housing cup of the filter housing for separation of a filter receiving space for the filter insert from a centrifuge receiving space for at least one centrifuge separator and configured to be mounted in the filter housing and removed from the filter housing by a rotary and/or insertion movement in respect to the axis; wherein the intermediate cover comprises at least a portion of at least one clean fluid channel configured to form a fluidic connection between a clean fluid side of the filter insert and at least one fluid outlet of the filter housing for a purified clean fluid, wherein the at least one clean fluid channel comprises at least one inlet opening; wherein the filter insert comprises at least one connecting device, arranged at a first axial end face, axial in respect to the axis, of the filter insert, wherein the at least one connecting device of the filter insert is configured to connect to the intermediate cover; wherein the filter insert comprises at least one outlet opening for purified clean fluid arranged at the first axial end face of the filter insert, wherein the at least one outlet opening of the filter insert is configured to correspond to the at least one inlet opening of the at least one clean fluid channel of the intermediate cover; wherein the at least one outlet opening of the filter insert at least partially forms the at least one connecting device.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0065] Further advantages, features, and details of the invention result from the following description in which an embodiment of the invention will be explained in more detail with the aid of the drawing. A person of skill in the art will expediently consider the features disclosed in combination in the drawing, the description, and the claims also individually and combine them to expedient further combinations.

[0066] FIG. 1 shows a longitudinal section of a filter for purifying liquid, with a filter insert and a centrifuge separator, between which an intermediate cover is arranged.

[0067] FIG. 2 shows a detail of a longitudinal section of the filter of FIG. 1 along a different section plane.

[0068] FIG. 3 shows a further detail of a longitudinal section of the filter of the FIGS. 1 and 2 along a further section plane.

[0069] FIG. 4 shows a detail of the longitudinal section of FIG. 3 in the region of a centrifuge-side seal between the intermediate cover and the filter housing.

[0070] FIG. 5 shows a longitudinal section of the filter insert of the filter of FIGS. 1 to 3 with the intermediate cover.

[0071] FIG. 6 shows an isometric partial section of the filter insert with the intermediate cover of the filter of FIGS. 1 to 3.

[0072] FIG. 7 shows a longitudinal section of the filter of the FIGS. 1 to 3 along a different section plane, wherein here a fluid drain for draining fluid is shown in the bottom of the filter housing.

[0073] In the Figures, same components are provided with same reference characters.

DESCRIPTION OF PREFERRED EMBODIMENTS

[0074] In FIGS. 1 to 7, a filter 10 for purifying liquid fluid is illustrated in various sections and detail views.

[0075] Particles can be removed from liquid fluids, for example, motor oil, fuel, water, urea-water solution, hydraulic liquid or the like by means of the filter 10. For this purpose, the filter 10 can be arranged in a corresponding liquid line, for example, of an internal combustion engine.

[0076] When in the following raw fluid is mentioned, this means in the context of the invention fluid to be purified by the filter 10. Clean fluid means fluid that has been purified by the filter 10. The raw fluid side is therefore the side at which the fluid to be purified is located. The clean fluid side is the side where the purified fluid is located.

[0077] The filter 10 comprises a filter housing 12 with a housing cup 14 which is closed off by a removable housing cover 16. The housing cup 14 as well as the housing cover 16 are embodied cup-shaped. The housing cover 16 is connected by a screw connection by a screwing action in respect to an imaginary axis 18. The housing cover 16 comprises for this purpose an outer thread and the housing cup 14 a corresponding inner thread.

[0078] When in following axial, radial, circumferential, coaxial or the like is mentioned, this relates to the axis 18, as long as nothing to the contrary is mentioned.

[0079] In the filter housing 12, a filter receiving space 20 for a filter insert 22 and a centrifuge receiving space 24 for a centrifuge separator 26 are provided. In an exemplary fashion, the filter receiving space 20 and the centrifuge receiving space 24 are coaxial and circular cylindrical, respectively. The filter receiving space 20 and the centrifuge receiving space 24 are separated from each other by an intermediate cover 28. In the normal installation position of the filter 10, as it is illustrated in FIG. 1, the filter receiving space 20 is arranged at the bottom in the housing cup 14. The centrifuge receiving space 24 is located spatially above the filter receiving space 20, partially in the housing cover 16. The intermediate cover 28 is screwed in, for example, below the free rim of the housing cover 16 into the inner thread of the housing cup 14. The intermediate cover 28 is located thus axially between the filter receiving space 20 and the centrifuge receiving space 24.

[0080] The filter housing 12 comprises a fluid inlet 30 for fluid to be purified. The fluid inlet 30 extends through the bottom of the housing cup 14 into the filter receiving space 20.

[0081] The fluid outlet 32 for purified fluid extends through the circumferential side of the housing cup 14. The fluid outlet 32 is located approximately at the level of the intermediate cover 28 in a region between the filter receiving space 20 and the centrifuge receiving space 24.

[0082] The opening of the housing cup 14 which can be closed off by the housing cover 16 serves as an installation opening for the filter insert 22, the intermediate cover 28, and a holding unit 60 of the centrifuge separator 26.

[0083] Moreover, a bypass channel 34 in which a bypass valve 36 is arranged extends centrally through the bottom of the housing cup 14. The bypass valve 36 extends axially into the filter receiving space 20. The bypass channel 34 connects directly the raw fluid side of the filter insert 22 with its clean fluid side. The bypass valve 36 releases the bypass channel 34 as soon as a corresponding pressure difference between the input side and the output side of the bypass valve 36 is present. This can be the case, for example, when a fluid passage through the filter insert 22 is blocked. In this way, a fluid flow through the filter 10 can still be ensured.

[0084] The filter insert 22 is, for example, a so-called round filter element. The filter insert 22 comprises a filter medium 38, for example, filter nonwoven or filter paper. The filter medium 38 surrounds the axis 18 circumferentially continuously and delimits circumferentially an insert interior 40 of the filter insert 22.

[0085] In the insert interior 40, a grid-type support pipe 42 is arranged which extends between the axial end faces of the filter insert 22. The support pipe 42 is open at both end faces. The circumferential wall of the support pipe 42 is permeable for liquid.

[0086] At the end face of the filter insert 22 which is facing the bottom of the housing cup 14, an inlet-side end disc 44 is arranged which is connected seal-tightly with the filter medium 38. The inlet-side end disc 44 comprises a coaxial opening through which the bypass valve 36 is extending. The opening and the region of the support pipe 42 thereat form a receptacle 46 for the bypass valve 36.

[0087] At the centrifuge-side end face which is facing the housing cover 16, a centrifuge-side end disc 48 is connected seal-tightly to the filter medium 38. The centrifuge-side end disc 48 comprises a central outlet opening 50 for purified fluid. The outlet opening 50 and the region of the support pipe 42 thereat belong to a connecting device 52 with which the filter insert 22 is connected to the intermediate cover 28.

[0088] The outer diameter of the filter insert 22, in particular the outer diameter of the end discs 44 and 48, are significantly smaller than an inner diameter of the housing cup 14. In this way, between the radially outer circumferential side of the filter insert 22 and the radially inner circumferential side of the housing cup 14, the fluid-conducting annular space 54 is formed at the raw fluid side of the filter insert 22.

[0089] Moreover, the inlet-side end disc 44 is held at an axial distance to the bottom of the housing cup 14 so that an end face inlet space 56 for fluid to be purified is produced between the inlet-side end disc 44 and the bottom of the housing cup 14. The fluid inlet 30 opens into the inlet space 56.

[0090] The centrifuge separator 26 comprises a holding unit 60, a rotor 58, and a bypass valve 62.

[0091] The holding unit 60 comprises a circular cylindrical, coaxial fastening section 64 with an outer thread and a central section 66. The central section 66 is located radially inside the fastening section 64 and is connected as one piece together therewith.

[0092] With the outer thread of the fastening section 64, the holding unit 60 is screwed into the inner thread in the region of the installation opening of the housing cup 14.

[0093] The central section 66 forms a separation wall between a centrifuge outlet space 68 and the intermediate cover 28. The central section 66 is convexly curved when viewed from the housing cover 16. The central section 66 comprises a coaxial centrifuge inlet 70 for fluid to be purified.

[0094] At the side which is facing away from the intermediate cover 28, a bottom support 72 for the rotor 58 adjoins the centrifuge inlet 70. A corresponding upper support 74 for the rotor 58 is arranged at the top in the bottom of the housing cover 16. The rotor 58 is supported, rotatable about axis 18, in the bottom support 72 and the upper support 74.

[0095] Moreover, the bypass valve 62 is arranged in the central section 66. By means of the bypass valve 62, a direct connection between an intermediate space 76 at the inlet side of the centrifuge separator 26 and the centrifuge outlet space 68 can be produced upon surpassing a predetermined pressure difference. In this way, the fluid can bypass the centrifuge separator 26 in case a fluid passage through the centrifuge separator 26 is blocked, for example, due to soiling.

[0096] At the side of the central section 66 which is facing axially away from the rotor 58, a coaxial holding cylinder 78 is arranged. The holding cylinder 78 is formed as one piece together with the central section 66. The holding cylinder 78 surrounds the centrifuge inlet 70 and the intermediate space 76 continuously in circumferential direction. The holding cylinder 78 extends axially in the direction toward the intermediate cover 28 and ends shortly before a centrifuge-side separation section 80 of the intermediate cover 28. Due to the distance between the free rim of the holding cylinder 78 and the centrifuge-side separation section 80, a circumferential passage for the fluid is realized.

[0097] At the radial inner circumferential side, the holding cylinder 78 comprises a circumferential locking groove in which corresponding locking hooks 82 of a holding device 84 of the intermediate cover 28 can lock.

[0098] The intermediate cover 28 comprises the centrifuge-side separation section 80 at the end face which is axially facing the centrifuge separator 26 and a filter-side separation section 88 at the side which is axially facing the filter insert 22. The separation sections 80 and 88 are designed each as a disc section. The separation sections 80 and 88 extend, for example, axially spaced apart and parallel to each other.

[0099] The separation sections 80 and 88 are connected as one piece with each other by means of a plurality of hollow cylinder sections 90. The imaginary axes of the cylinder sections 90 extend in an exemplary fashion parallel to the axis 18. The interiors of the cylinder sections 90 form a raw fluid channel 92, respectively. The cylinder sections 90 and thus the raw fluid channels 92 are arranged circumferentially distributed. The raw fluid channels 92 connect the raw fluid side of the filter insert 22 with a centrifuge inlet space 94.

[0100] The centrifuge inlet space 94 surrounds circumferentially the holding cylinder 78 of the holding unit 60 of the centrifuge separator 26. The centrifuge inlet space 94 is connected by means of the passage gap between the holding cylinder 78 and the centrifuge-side separation section 80 with the intermediate space 76 and through the latter with the centrifuge inlet 70.

[0101] An intermediate space between the separation sections 80 and 88 forms as a whole a clean fluid channel 96. The clean fluid channel 96 is open in radially outward direction circumferentially continuously and forms thereat an outlet opening 98. The cylinder sections 90 with the raw fluid channels 92 pass through the intermediate space which forms the clean fluid channel 96. In this context, the raw fluid channels 92 are separated with the walls of the cylinder sections 90 from the clean fluid channel 96.

[0102] When the intermediate cover 28 is mounted, the outlet opening 98 corresponds with an annular outlet space 100. Due to the circumferentially extending continuously open outlet opening 98, the connection to the annular outlet space 100 is produced independent of the rotational orientation of the filter insert 22 in respect to the filter housing 12. The annular outlet space 100 surrounds the intermediate cover 28 circumferentially and is connected to the fluid outlet 32. In this manner, the outlet opening 98 corresponds with the fluid outlet 32.

[0103] The filter-side separation section 88 comprises moreover a central inlet opening 102 for purified fluid. The inlet opening 102 opens into the clean fluid channel 96.

[0104] At the side of the filter-side separation section 88 which is axially facing away from the centrifuge-side separation section 80, a filter centering device 104 in the form of a hollow cylinder extends in axial direction. The filter centering device 104 is circumferentially closed at its side which is facing the filter-side separation section 88.

[0105] The radially outer circumferential side of the filter centering device 104 comprises a circumferentially continuous sealing device 105 with which a sealing action against a radially inner circumferential side of the centrifuge-side end disc 48 is provided. Thus, the outlet opening 50 is sealed against the intermediate cover 28. The sealing device 105 separates the raw fluid side from the clean fluid side.

[0106] At the side which is axially facing away from the filter-side separating section 88, the filter centering device 104 comprises a plurality of circumferentially distributed locking arms 106. The locking arms 106 can lock at the support pipe 42 of the filter insert 22 and therefore center the latter relative to the intermediate cover 28. In this context, the outlet opening 50 and/or the support pipe 42 form a connecting device on the part of the filter insert 22 for connection with the intermediate cover 28.

[0107] Moreover, on the end face of the filter-side separation section 88 which is axially facing away from the centrifuge-side separation section 80, a plurality of spacers 108 is arranged circumferentially distributed. The spacers 108 extend in axial direction, respectively. By means of the spacers 108, an axial distance between the filter-side separation section 88 and the centrifuge-side end disc 48 of the filter insert 22 is predetermined. An end face raw fluid space 110 is thus realized between the filter-side separation section 88 and the centrifuge-side end disc 48. The raw fluid channels 92 extend away from the raw fluid space 110.

[0108] At the radially outer rim, the filter-side separation section 88 passes into a filter-side cylinder section 112 in a one-piece configuration. The cylinder section 112 surrounds the part of the filter insert 22 which is axially facing the intermediate cover 28. The filter-side separation section 88 with the filter-side cylinder section 112 has overall a cup-shaped.

[0109] In the region of the free rim of the filter-associated cylinder section 112, a sealing groove is provided radially outwardly with a circumferentially continuous annular seal 114.

[0110] The centrifuge-side separation section 80 comprises the locking hooks 82 at its side which is axially facing away from the filter-side separation section 88. The locking hooks 82 are circumferentially distributed and extend each in axial direction.

[0111] The circumferential rim of the centrifuge-side separation section 80 passes into a centrifuge-side cylinder section 116 in a one-piece configuration. The centrifuge-side cylinder section 116 extends in axial direction away from the filter-side separation section 88. As a whole, the centrifuge-side cylinder section 116 and the centrifuge-side separation section 80 have a cup shape.

[0112] At the radial outer circumferential side, a circumferentially continuous half-moon seal 118 is arranged at the centrifuge-side cylinder section 116. The half-moon seal 118 has approximately the shape of a half moon in profile.

[0113] When the filter 10 is mounted, the annular seal 114 seals in radial direction against the radially inner circumferential side of the circumferential wall of the housing cup 14. The annular seal 114 is located at the side of the fluid outlet 32 which is axially facing away from the installation opening of the housing cup 14. Thus, the annular seal 114 seals the raw fluid side of the filter insert 22 against the clean fluid side.

[0114] The half-moon seal 118 is illustrated in detail in FIG. 4. When the filter 10 is mounted, the half-moon seal 118 is arranged in a region between the fastening section 64 of the holding unit 60 of the centrifuge separator 26 and the radially inner circumferential side of the housing cup 14. In this context, the half-moon seal 118 acts seal-tightly in radial direction as well as in axial direction. Due to the axial compression between the rim of the fastening section 64 at the axial end face and a step 120 on the part of the housing cup 14, on the one hand, the axial sealing action is generated. Due to the axial compression, the half-moon seal 118 yields in radial direction so that the radial sealing action is improved. In this way, a plurality of sealing locations can be sealed radially and axially by means of the half-moon seal 118.

[0115] In operation of the filter 10, the raw fluid flows through the fluid inlet 30 into the annular space 54. The flow of the raw fluid through the filter 10 is indicated by solid arrows. A portion of the raw fluid flows from the annular space 54 in a radial direction from the exterior inwardly into the insert interior 40 through the filter medium 38 and the fluid-permeable support pipe 42. The purified fluid exits from the insert interior 40 through the inlet opening 102 and reaches the clean fluid channel 96. From the clean fluid channel 96, the purified fluid flows into the fluid outlet 32 of the filter housing 12 and exits from the filter 10.

[0116] Another portion of the raw fluid is diverted from the annular space 54 to the centrifuge separator 26. This portion of the raw fluid is indicated in FIG. 1 by dotted arrows. The raw fluid flows in this context into an annular gap 122, arranged radially between the radial outer circumferential side of the filter insert 22 and the radial inner circumferential side of the filter-side cylinder section 112. The raw fluid flows from the annular gap 122 into the end face raw fluid space 110. From here, the raw fluid flows through the raw fluid channels 92 into the centrifuge inlet space 94. Through the gap between the hollow cylinder 78 and the centrifuge-side separation section 80, the raw fluid reaches the intermediate space 76. From here, the raw fluid flows through the centrifuge inlet 70 into the rotor 58. With the rotor 58, particles are removed from the raw fluid in a manner generally known, which is not of interest here. The purified fluid sinks, following the force of gravity, in downward direction, exits the rotor housing of the rotor 58 through corresponding openings, not of interest here, and passes into the centrifuge outlet space 68. From the centrifuge outlet space 68, the purified fluid flows into the fluid outlet 32 of the filter housing 12.

[0117] Should a differential pressure between the raw fluid side and the clean fluid side of the filter insert 22 surpass a predetermined value, for example, due to loading of the filter insert 22 with dirt, the bypass valve 36 is opened so that the raw fluid can flow directly into the insert interior 40 and from there, as described above, can exit from the filter 10 through the fluid outlet 32.

[0118] Should a differential pressure between the intermediate space 76 and the centrifuge outlet space 68 of the centrifuge separator 26 surpass a predetermined value, for example, due to a disturbance, the bypass valve 62 is opened so that the raw fluid can flow directly to the fluid outlet 32 by bypassing the centrifuge separator 26.

[0119] In FIG. 7, the filter 10 is illustrated in a different longitudinal section in which a fluid drain 126 can be seen in the bottom of the housing cup 14. By means of the fluid drain 126, a passage can be released automatically through which fluid contained in the filter housing 12 can drain upon removing the filter insert 22. The fluid drain 126 can be automatically actuated for closing by the inlet-side end disc 44 in that the latter pushes against a corresponding actuating mechanism of the fluid drain 126 in axial direction toward the bottom of the housing cup 14. The inlet-side end disc 44 is therefore a part of the actuating device for the fluid drain 126. The axial extension of the filter insert 22 is dimensioned such that, when screwing in the holding unit 60, the latter pushes the intermediate cover 28 axially downwardly so that the intermediate cover 28, in turn, pushes the filter insert 22 axially against the actuating mechanism of the fluid drain 126 and the latter is actuated for closing.