GB2544055A

GB2544055A - Centrifugal seperator with drainage slots

Info

Publication number: GB2544055A
Application number: GB1519419.4A
Authority: GB
Inventors: Marques Tiago; Nash Robin; Rouse Angus; William Fell Anthony
Original assignee: Mann and Hummel GmbH
Current assignee: Mann and Hummel GmbH
Priority date: 2015-11-03
Filing date: 2015-11-03
Publication date: 2017-05-10
Anticipated expiration: 2035-11-03
Also published as: GB201519419D0; CN107096649A; CN107096649B; GB2544055B

Abstract

A centrifugal separator comprises a stationary housing 10 defining an enclosure and a rotor 12 mounted for rotation inside the enclosure. The housing 10 includes a base 14 having a circumferential wall 24, a cover 16 which is releasably connected to the circumferential wall 24 of the base 14 to provide an upper region of the enclosure around the rotor 12, and sealing means 26 disposed between a lower end margin of the cover 16 and an upper margin 25 of the circumferential wall 24. The circumferential wall 24 of the base 14 has an upstanding lip 30 extending inside a lower portion of the cover 16 with an annular gap (35, fig 4) there between. A plurality of openings 40 is provided in the upstanding lip 30 to enable drainage of working fluid into the base 14 of the housing 10. These openings 40 may be recesses 40 in the upper edge of the lip 30 and preferably extend to the bottom of the lip 30.

Description

Centrifugal separator with drainage slots [0001] This invention relates to a centrifugal separator, particularly but not exclusively a self-driven fluid powered centrifugal separator.

BACKGROUND

[0002] Fluid powered centrifugal separators are well-known for separating fluids of different densities or for separating particulate matter from liquids and have long been used in lubrication systems for engines, particularly diesel powered vehicle engines (automobiles and ships), as well as in other industrial separation processes. The principle of operation of such a separator is that a housing contains a rotor which is supported therein to spin at high speed about an axial spindle. Fluid is supplied at elevated pressure along the axis of rotation and passes through apertures in the axial spindle and in a central tube of the rotor into the chamber of the rotor. After circulation within the rotor chamber, the fluid is ejected from nozzles in the base of the rotor into the housing from which it drains to a sump. In self-powered separators the drive fluid for the rotor is the contaminated fluid which is to be cleaned. As this fluid passes through the rotor, denser contaminant materials or particles are separated from the fluid by centrifugal force and are retained in the rotor, typically as a cake adhering to the interior surface of the rotor. During servicing of the separator, the housing, which comprises a base and a cover, is opened to access the rotor, which has to be disassembled and cleaned out. This may be done, for example, once or twice a year during vehicle servicing in the case of centrifugal separators in automotive vehicles, or may be done much more frequently in other industrial uses of centrifugal separators.

[0003] During operation, the majority of fluid exiting the nozzles in the base of the rotor flows downwards and returns to the sump via an outlet in the base of the housing. However, a portion of the fluid tends to collect in a region where the housing cover connects to the base of the housing and then spills out when the cover is released from the base to allow servicing of the rotor. In this respect, the base of the housing has a circumferential wall to which the cover is releasably connected with sealing means arranged between a lower end margin of the cover and an upper margin of the circumferential wall. The circumferential wall has an upstanding lip which projects inside the lower portion of the cover with an annular gap there between. It is in this gap and above the lip in which a portion of the fluid tends to accumulate.

[0004] An object of the present invention is to reduce or eliminate such spillage, which is messy and undesirable.

SUMMARY OF THE INVENTION

[0005] The present invention provides a centrifugal separator comprising a stationary housing defining an enclosure and a rotor mounted for rotation inside the enclosure, the housing comprising a base having a circumferential wall, a cover which is releasably connected to the circumferential wall of the base to provide an upper region of the enclosure around the rotor, and sealing means disposed between a lower end margin of the cover and an upper margin of the circumferential wall. The circumferential wall of the base has an upstanding lip extending inside a lower portion of the cover. A plurality of openings is provided in the upstanding lip to enable drainage of working fluid into the base of the housing.

[0006] By this measure, fluid passing through the separator is enabled to drain from adjacent the lower margin of the cover into the base of the housing, reducing the volume of accumulated fluid. Spillage when the housing cover is removed is thereby significantly reduced and may be eliminated.

[0007] These openings in the lip (which may also be termed slots in the lip) may be formed as recesses at spaced intervals around the upper edge of the lip. Consequently, the upper edge of the lip becomes discontinuous. Preferably, each recess, which is essentially an elongated notch in the lip, extends to the bottom of the lip. This will more likely eliminate such spillage, as drainage possibility is maximised.

[0008] However, in alternative embodiments of the invention the openings or slots may be formed as holes which are not open to the upper edge of the lip, i.e. they have a closed periphery. In such embodiments, these holes are preferably formed to extend to the bottom of the lip. Such openings may also be of elongated shape.

[0009] A further aspect of the invention is a housing base, per se, for a centrifugal separator, said base having a circumferential wall provided with an upstanding lip around its upper edge, said lip being formed with a plurality of drainage openings.

[0010] In relation to other aspects of the design of the separator, the axial position of the lower end of the openings in the lip may vary. However, it is preferred that the lower end of the openings should be at the same level or above an upper end face of the sealing means. In a preferred embodiment, the axial distance between lower end of the openings and upper end face or upper surface of the sealing means should be no more than 5 mm, especially no more than 2 mm, preferably no more than 1 mm.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The invention will be described further, by way of example, with reference to the accompanying drawings, in which:

Figure 1 is a longitudinal cross-section through an embodiment of the centrifugal separator in accordance with the invention;

Figure 2 is a perspective view of the base of the housing of the separator of figure 1;

Figure 3 is a perspective view of the separator of figure 1 with the housing cover and base partially cut away; and

Figure 4 is an enlarged detail of the region, encircled in figure 1 where the housing cover fits to the housing base.

DETAILED DESCRIPTION

[0012] As shown, this exemplary embodiment of centrifugal separator of the invention is a self-powered separator where the working fluid providing rotary drive is also the fluid from which contaminants are to be centrifugally separated. The separator comprises a stationary housing 10 defining an enclosure and a rotor 12 which is mounted inside the enclosure. The housing 10 comprises a base 14 providing a lower region of the enclosure and a cover 16, which is releasably connected to the base to provide an upper region of the enclosure. An axial spindle 18 is rigidly mounted to the base 14 and extends to a connector assembly 20 at the top of the cover 16. The rotor 12 is mounted on the spindle 18 for rotation thereabout during operation of the separator.

[0013] The base 14 of the housing 10 has a circumferential wall 24 with an upper edge portion 25 defining an annular groove locating a sealing ring 26. A lower margin of the cover 16 has a matching flared configuration and is releasably connected by clamping device 28 to contact the sealing ring 26. The circumferential wall 24 is provided with an upstanding lip 30 which extends inside a lower portion of the cover 16 with a narrow annular gap 35 there between. The gap 35 is indicated in the detail of figure 4 as a narrow space between the outer surface of the lip 30 and the inner surface of the cover 16. This lip 30 is important as a guide for location of the cover 16 onto the upper edge of the base 14 in a position to achieve even compression of the O-ring seal 26 when the clamping device 28 is re-secured at the end of each servicing operation. In prior art separators this lip 30 is a continuous circumferential lip.

[0014] Operation of the centrifugal separator is conventional. Pressurised working fluid is supplied through an inlet 32 in the base 14 of the housing 10. From here, the working fluid flows through a central channel 38 of the spindle 18 and passes into the rotor 12 by way of radial holes 31, 33 in the wall of the spindle and in a central tube 13 of the rotor 12. The fluid circulates in the rotor 12 as shown in figure 1. Firstly it flows to the inner surface of the rotor drum, where the centrifugal force causes deposit of contaminant particles. The fluid is then deflected inwards by a separation cone 34 and passes through a gap at the inner edge of the cone 34, and downwardly to exit through nozzles 36 at the bottom of the rotor 12. It is the tangential emission of fluid from these nozzles 36 (only one of which is shown in figure 3) at a distance from the axis of rotation which provides the driving force to rotate the rotor 12. The angular velocity of the rotor generates the centrifugal force to separate out the contaminant particles by causing their accumulation on the inner surface of the rotor drum.

[0015] The majority of fluid exiting the nozzles 36 flows downwards and returns to a sump (not shown) through an outlet 37 in the base 14 of the housing 10. However, a portion of fluid exiting the nozzles 36 has hitherto accumulated in the area 50 above the sealing ring 26, where the housing cover 16 is clamped to the housing base 14, as indicated in figure 4. In particular, fluid accumulated in the narrow gap 35 between the upstanding lip 30, which hitherto has been a continuous circumferential lip, and the inner surface of the cover 16, as well as above that lip 30.

[0016] Periodically, the separator has to be serviced and the interior of the rotor 12 cleaned out. Accordingly, to allow access to the rotor 12 the housing 10 has first to be opened by release of the clamping device 28 and lifting away of the housing cover 16. As the housing cover is lifted away, the accumulated fluid in area 50, which is typically oil, spills over to the outside of the housing base 14, which is troublesome to service operators and requires mopping. This reduces the efficiency of the servicing procedure.

[0017] Now, in accordance with the invention, this exemplary embodiment shows the sealing lip 30 as discontinuous, with respective part-annular lip portions 30 separated by recesses or slots 40 cut in from the top of the lip 30 and extending to the bottom of the lip 30. The illustrated embodiment is shown, in figure 2, as having eight upstanding lip portions 30 separated by eight intervening elongate slots 40. The lip portions 30 and the intervening slots 40 are of approximately equal angular extent (therefore each approximately 22.5°). Further, the bottom surface 42 of each of the elongate slots 40 is provided at an angle, sloping downwards towards the centre of the housing base 14. The provision of slots 40 per se enables drainage of fluid from the gap 35 behind, namely outward of, the upstanding lip 30. Inclination of the base of each slot 40 further facilitates drainage of fluid. Consequently, when the clamp assembly 28 is released and the cover 16 lifted away, there is no spillage of fluid, or only minimal amount.

[0018] For a reliable function of the sealing ring 26, the annular groove 27 in which the sealing ring is located should have continuous surfaces, preferably on all three sides. Therefore, the lower end of the slots 40 should be located slightly above or at the same level as the upper end face of the sealing ring 26 (see Fig. 4).

[0019] It should be understood that the illustrated embodiment is only by way of example, as already stated. The invention is not restricted to specific details of the illustrated embodiment. Many variations in detail are possible in other embodiments. In particular, the geometry, number and spacing of recesses in the upstanding lip of the housing base may be different in other embodiments within the scope of the invention. While a reasonable number, say three or more recesses will typically be suitable to achieve the required drainage, and absence of spillage when the housing is opened, any number of such recesses is possible. Further, the recesses do not have to be approximately the same length as each other or as the remaining intervening upstanding lip portions. The recesses may be longer or shorter than the lip portions and may be of different lengths at different places around the circumference of the wall of the housing base. In other embodiments the recesses may not extend fully to the base of the upstanding lip. Also, in other embodiments the bottom of the respective recesses may not be sloping. In yet other embodiments, in place of recesses, there may be openings through the lip which will also provide adequate drainage so as to reduce spillage of fluid when the housing cover is released and removed in the servicing procedure. In other words, the principle is applicable in respect of any number of openings or recesses (slots) in the lip around the upper edge of the housing base irrespective of the size or geometry of those openings or recesses.

[0020] Additionally, in other embodiments within the invention the configuration of the upper end of the circumferential wall of the housing base and the lower margin of the cover may be different and the sealing and clamping arrangement between the housing cover and housing base may differ from the illustrated embodiment.

[0021] The invention may also be applicable to a centrifugal separator which has separate drive means and is not self-powered.

Claims

1. A centrifugal separator comprising a stationary housing (10) defining an enclosure and a rotor (12) mounted for rotation inside the enclosure, the housing comprising a base (14) having a circumferential wall (24), a cover (16) which is releasably connected to the circumferential wall of the base to provide an upper region of the enclosure around the rotor, and sealing means (26) disposed between a lower end margin of the cover and an upper margin (25) of the circumferential wall, the circumferential wall (24) of the base (14) having an upstanding lip (30) extending inside a lower portion of the cover with an annular gap there between, characterised in that a plurality of openings (40) are provided in the upstanding lip (30) to enable drainage of working fluid into the base (14) of the housing (10).

2. A centrifugal separator according to claim 1 wherein each opening (40) extends to the bottom of the lip (30).

3. A centrifugal separator according to claim 1 or 2 wherein the openings have lower ends which are at the same level or above an upper end face of the sealing means.

4. A centrifugal separator according to claim 1,2 or 3 wherein the plurality of openings (40) are formed as recesses in the upper edge of the lip (30).

5. A centrifugal separator according to claim 4 wherein each recess (40) has a bottom surface (42) which slopes downwardly towards the inside of the base (14) of the housing (10).

6. A centrifugal separator according to any preceding claim wherein the openings (40) in the upstanding lip (30) are distributed at spaced intervals around the circumferential wall (24) of the housing base (14).

7. A centrifugal separator according to any preceding claim wherein the openings (40) are provided in the upstanding lip (30) at equal spacing around the circumferential wall (24) of the housing base (14).

8. A centrifugal separator according to any preceding claim wherein four or more openings (40) are provided in the upstanding lip (30).

9. A centrifugal separator according to any preceding claim which is a self-powered centrifugal separator.

10. A base (14) for a centrifugal separator, the base having a circumferential wall (24) provided, around its upper edge, with an upstanding lip (30) which, in use, extends inside a lower portion of a cover (16) to provide an enclosure for a rotor (12), said lip (30) being formed with a plurality of drainage openings (40).

11. A base (14) according to claim 9 wherein the plurality of openings (40) are formed as recesses in the upper edge of the lip (30).