WO1999030827A1

WO1999030827A1 - Centrifugal separator control valve arrangement

Info

Publication number: WO1999030827A1
Application number: PCT/GB1998/003570
Authority: WO
Inventors: Ian Malcolm Cox; Andrew Leonard Samways
Original assignee: Federal-Mogul Engineering Limited
Priority date: 1997-12-13
Filing date: 1998-12-03
Publication date: 1999-06-24
Also published as: GB9726336D0; ZA9811318B

Abstract

A control valve (80) for a self powered centrifugal separator (15') that is suitable for cleaning engine lubricant comprises a housing (17) having a blind bore (102) of circular cross-section into which open inlet and oulet ducts (40' and 40'') and containing a valve body (84). The valve body consists of a first part (111), which is axially fixed and rotatable between valve-open and valve-closed positions, and a second part (112), axially displaceable but rotatable with the first part by way of axially overlapping coupling parts (161 and 162). A control chamber (120) is defined between the blind end (104) of the bore and an end face (121) of the second part and a bias spring (131) extends between the other end face and the first part. A control passage (140) extends along the second part and flow passage (150) through it. The bias spring normally puts the flow passage out of alignment with the ducts but when the valve-open orientation is selected inlet duct pressure is transmitted by the control passage to the control chamber and the first part (111) deplaced to effect a predetermined degree of alignment between ducts. Under- or over-pressure displaces the part (111) and decreases flow. As the valve-closed orientation is selected the control passage and outlet duct drains the control chamber and permits the part (111) to be biased with the flow passage out of alignment. The control passage (140) senses the liquid pressure and acts on the body part directly, but alternatively, a separate pressure (or flow) sensor could supply control signals to an externally powered actuator.

Description

Centrifugal Separator Control Valve Arrangement

This invention relates to centrifugal separators for cleaning solid contaminants from a liquid that is passed through a container thereof rotated at high speed, and in particular to a control valve arrangement for controlling the supply of liquid to the container.

Patent specification GB-A-2311239, the contents of which are incorporated herein by reference, describes a centrifugal liquid cleaning arrangement, specifically a centrifugal separator of the self- powered type in which the delivery pressure of liquid supplied to it comprises the source of energy for centrifugal rotation. The separator described therein and that to which the present invention relates are both particularly suited to cleaning liquid lubricant pumped under pressure around an internal combustion engine or other machine.

One of the embodiments described and illustrated in the above mentioned specification is reproduced herein as Figure 6. It is not described here in full detail but shows centrifugal separator 15 having a housing base 17 with a first surface 18, adapted to be mounted against a substantially horizontal mounting surface 14 of a machine 11 in which liquid lubricant is circulated by pumping from a reservoir, and a second surface 19, on the opposite side of the base, which is generally upwardly facing and recessed to form a collection region 20. The collection region is connected to liquid drain passage 21 which extends from the collection region to said first surface 18.

Spindle means 25 comprises a static spindle fixed to, and extending from, the second surface 19 and contains an axially extending spindle passage 27 open at one end 28 thereof towards the base and at the other end by way of lateral cross-drillings 29 in the spindle wall.

A rotor 30 supported on the spindle for rotation thereabout comprises a bearing tube 31 extending along, and surrounding, the spindle and arranged to receive liquid from the spindle passage by way of the cross drillings 29. The bearing tube also supports, and defines therearound, an annular contaminant container 32, which container is in liquid flow communication with the spindle passage by way of apertures 33 in the bearing tube and is in communication with the collection region 20 by way of tangentially directed reaction nozzle means 34 formed in the base of the container. A removable cover 35 encloses the rotor and collection region, the upper part of the cover surrounding the upper end part 25' of the spindle and being secured, exerting a limited axially directed pressure, by a nut arrangement 38. A liquid supply duct 40 extends through the base 17 between the end 28 of the spindle passage and said first surface 18.

The base 17 also has a control valve arrangement, indicated generally at 45, which comprises a valve housing (the base 17) in which is formed a valve space 46 as a bore extending through the housing from a third surface 47 of the base and intersecting the supply duct 40. The bore 46 defines inter alia a portion 48 of the supply duct which extends along the axis 49 of the bore between a first, or inlet, duct section 40' of the supply duct, which extends from the first surface 18 to the bore, and a second, or outlet, duct section 40" of the supply duct which extends from the bore to the spindle passage.

A manually operated control valve 50 has a valve body which extends along the bore and is displaceable with respect thereto between a valve-open position (shown), in which it permits passage of liquid to the spindle passage, and a valve-closed position, in which it inhibits the supply of liquid to the spindle passage.

The valve bore and valve body are circular in cross-section and the valve body is rotatable about the common longitudinal axis 49 to effect the displacement between valve-open and valve-closed positions.

An end part 55 of the valve body extends from the valve bore at the third surface 47 of the base and has secured thereto handle means 56 by which the valve body may be rotatably displaced, and it will be seen that by movement of the handle means to rotate the valve body to a valve-closed position, supply of liquid to the spindle passage is blocked and the cover 35 and rotor 32 may be safely removed.

The control valve arrangement 45 also includes a cut-off valve 70 which is responsive to liquid pressure below a predetermined minimum level to prevent liquid from being delivered from the spindle passage. The cut-off valve 70 is disposed in valve bore 46 and comprises a piston 71 extending along the bore and overlying the end of the outlet duct 40", being biased by spring 72 towards the valve body and restrained by a shoulder 73. In response to liquid pressure in excess of said minimum level required to overcome the bias of spring 72, the piston is displaced to permit liquid passed by the valve body to enter the spindle passage.

Notwithstanding the precise forms and purposes of the manual control valve 50 and the low pressure cut-off valve 70 within the context of the above specification, the presence per se of a manual control valve and of a low pressure cut-off valve is known in centrifugal separators of this type.

As is well known, such centrifugal separator functions as a by-pass device, diverting surplus pumped liquid through it and returning it to a sump having utilised the energy of that liquid to effect centrifugal rotation of container 32 When, for whatever reason, liquid supply pressure is low, it is clearly both unwise to divert any liquid away from its intended use and wasteful if the pressure is insufficient to cause centrifugal rotation Hence the cut-off valve 70 serves to close this by-pass automatically if delivery pressure is below a predetermined value It will be appreciated that even when delivery pressure at the inlet duct 40' is above the predetermined minimum, the stiffness of the valve spring 72 causes the valve to introduce an impedance into the supply path, as does the change in direction at the manual control valve 45 necessary to accommodate the low pressure cut-off valve in the path If on the other hand, the delivery pressure is excessive, the control valve arrangement offers no response and ensures that the centrifugal separator sees this unaltered

It will also be appreciated that although liquid supply pressure represents the total pressure drop across the separator between duct 40' and drain 21 , the supply pressure also influences the flow rate of liquid through the separator It is also known in the art, for example from US 4046315, US 4106689 and WO 96/21511 that drainage of spent liquid from the housing, and maintenance of suitable atmosphere pressure within the housing is crucial to efficient separation, so that the rate at which liquid flow through the separator may be of greater impart than the supply to, or other pressure in, the separator

It is an object of the present invention to provide for a self-powered centrifugal separator of liquid supplied thereto at elevated pressure, a control valve arrangement that provides more control over a particular parameter of the liquid to maintain optimum separation efficiency It is also an object of the present invention to provide a self-powered centrifugal separator incorporating such a control valve arrangement It is a further object to provide for a self-powered centrifugal separator a control valve arrangement that provides manual and pressure-related control more simply and efficiently than known arrangements

According to a first aspect of the present invention a control valve arrangement for a self-powered centrifugal separator comprises a valve housing, containing a valve space, an inlet and an outlet duct each opening into a wall of the valve space and arranged respectively to deliver liquid at elevated pressure to, and lead it from, the valve space, valve body means, disposed in the valve spacing, arranged to control the flow between the inlet and outlet ducts, valve control means comprising sensor means, disposed in the centrifugal separator, operable to provide a sensor signal representing a value of a parameter of the liquid, and valve body positioning means operable in response to said sensor signal to set the disposition of at least a part of the valve body means to attempt to maintain said parameter of liquid led from the valve space within a predetermined range of values

Conveniently, the liquid parameter sensed is the pressure thereof, preferably at the inlet or outlet duct

According to a second aspect of the present invention a self-powered centrifugal separator of solid contaminants from a liquid lubricant, adapted to be operably mounted against a mounting surface of a machine in which said liquid lubricant is circulated by pumping from a reservoir, comprises i) a base having a first surface thereof adapted to be mounted in an operable disposition against a said mounting surface of a machine and a second surface arranged with respect to said first surface to lie, with said first surface so mounted, to be generally upwardly facing, ii) a liquid drain passage extending through the base from a collection region in said second surface to a surface other than the second surface, iii) spindle means extending from said second surface of the base along an operably substantially vertical axis above the collection region and containing an axially extending spindle passage, iv) a rotor, supported on the spindle means for rotation thereabouts, having an annular contaminant container in communication with the spindle passage and, by way of reaction nozzle means, with the collection region, said annular contaminant container being operable in response to receipt of said pumped liquid lubricant from the spindle means at elevated pressure and ejection thereof from the reaction nozzle means to effect rotation about the spindle means at such speed as to separate said solid contaminants from the liquid lubricant within the contaminant container, v) a removable cover supported on the base and enclosing the rotor and collection region, vi) a liquid lubricant supply duct extending through the base between said spindle passage and a surface other than said second surface, and is characterised by vii) control valve means as defined in the last but one paragraph, formed within the base as a valve housing.

Embodiments of the invention will now be described with reference to the accompanying drawings, in which:

Figure 1 is a schematic sectional elevation through a centrifugal separator in accordance with the invention, illustrating the major components of the control valve arrangement and particularly sensor means parameters and locations,

Figure 2(a) is a more detailed sectional elevation through a self-powered centrifugal separator in accordance with the invention, showing a control valve arrangement responsive to the parameter of supply pressure and comprising a valve body of manually movable valve and pressure responsive parts,

Figure 2(b) is an enlarged view of the region of Figure 2(a) containing the valve arrangement, shown in initial valve-open disposition,

Figure 2(c) is a view similar to Figure 2(b) but showing the arrangement in full valve-open disposition,

Figure 2(d) is an end view of the region of Figure 2(c) illustrating the orientation of the various passages as the valve is closed,

Figure 3 is a schematic view of part of a second embodiment of the valve arrangement that is arranged to have the flow passage and ducts only partially aligned in normal operation so that abnormal conditions can both reduce and increase the alignment, Figure 4 is a schematic view of a part of a third embodiment of the valve arrangement that is arranged to divert, rather than block, liquid flow at high pressure,

Figures 5(a) to 5(d) are schematic views of part of a third embodiment of the valve arrangement illustrating control associated with outlet duct pressure, and

Figure 6 is a sectional elevation through a known form of self-powered centrifugal separator showing liquid supply ducts and manual control and low-pressure cut-off valves associated therewith.

Referring to Figure 1, in a centrifugal separator 15', generally of the type described above with reference to Figure 6 and using like reference numerals where there is identity, the base 17 thereof comprises a valve housing (as distinct from the separator housing for a control valve arrangement, indicated generally at 80. The housing has formed within a valve space 82 into a wall of which open inlet and outlet ducts 40' and 40" respectively. The control valve arrangement includes valve body means, indicated generally at 84 which has at least part which is movable in the valve space to various dispositions at which it controls the flow of liquid between the inlet and outlet ducts. The control valve arrangement further comprises valve control means, indicated generally at 86, which in turn comprises sensor means 88 disposed in the separator and operable to provide a sensor signal representing a value of a parameter of the liquid, and valve body positioning means 90 operable in response to said sensor signal to set the disposition of at least a part of the valve body means to attempt, within the constraints of other criteria placed on the physical valve design, to attempt to maintain the parameter of liquid led from the valve space by duct 40" within a predetermined range of values.

The valve body positioning means 90 comprises a controller 92, actuator means 94 connected to the body part and a bias means 96 against which the actuator means works to define the disposition of the valve body part in relation to the inlet and outlet ducts. As illustrated, liquid parameter sensed at 88 is the pressure in the inlet duct 40' which is made available to the controller 92.

In principle, operation comprises sensing a change in supply pressure and varying the valve body position to maintain the outlet duct pressure within a range of values. In its simplest, the sensor means detects when supply pressure is low and a pressure necessary for centrifuge rotation cannot be maintained, the result being that the valve body is disposed to cut off the flow altogether. Also, the sensor signal detects an excessive supply pressure and causes the valve body to be disposed such that flow constricted and non-excessive pressure maintained in the outlet duct. It will be appreciated that the maintenance of flow is not under complete control; if the supply pressure falls significantly then there is little that the valve body can do below a certain pressure than to close off the supply of liquid and avoid wasted on a non-functioning centrifuge.

Preferably, but not essentially, the valve body means is displaceable within the housing under manual control, schematically illustrated at 98, between a valve-closed state, in which the valve body means prevents liquid flow between said inlet and outlet ducts, and a valve-open state, in which said disposable part is displaceable by said control means in response to said sensor signal.

It will be appreciated that the sensor means may be arranged to sense the pressure in the outlet duct, as indicated at 88', or indeed may determine the flow rate if the liquid in the outlet duct at 88" and base control on maintaining flow rate instead of pressure.

The above-described arrangement is highly schematic and a more practicable embodiment, which is based upon the centrifugal separator arrangement of Figure 6, will now be described in detail.

Referring to Figure 2(a) this shows in sectional elevation a centrifugal separator 15' and parts which are identical to any described above with reference to Figure 6 have identical reference numbers and will not be described further. The separator 15' of Figure 2(a) has in that the inlet duct section 40' of the supply duct 40 aligned along its axis with outlet duct section 40" and control valve arrangement 45 of separator 15 is replaced by control valve arrangement 80 in accordance with the present invention.

Referring also to Figures 2(b) to 2(d), which show the control valve arrangement 80 in greater detail, the valve housing is formed by the base 17 of the separator and the valve space therein comprises a bore 102 extending from a first, actuation, end 103 to a second, blind, end 104 of the bore and into the wall of which the bore opens the inlet duct 40' and outlet duct 40".

Valve body means, indicated generally at 84, is contained in the bore and comprises a first, or manual control, part 111 and second, displaceable, part 112.

The bore 102 and the first and second parts of the valve body are circular in cross-section, as seen in Figure 2(d), the parts forming a sliding fit within the bore and being rotatable in the bore about a common longitudinal axis 115.

The manual control part 111 of the valve body is substantially fixed axially by way of retaining pin 116 and complementary recess 117. With seal 118 the part 111 forms a closure for the bore at the actuation end thereof and is manually displaceable between a valve-open position, defining the valve-open state, and a valve-closed position, defining the valve-closed state. The retaining pin and recess also define limits of rotation of the part about the axis 115 between a valve-open position, as shown, and a valve- closed position displaced through 180° therefrom.

The displaceable part 112 of the valve body is not only rotatable about longitudinal axis 115 but is also, by virtue of its side wall 119 forming a sliding fit with the bore, translatable along the bore axis relative to the manual control part 111. For convenience of the description the manual control part and displaceable part are hereafter referred to as the first and second parts respectively.

Actuation means 94 is provided by a control chamber 120 defined in the closed section of the bore adjacent the blind end 104 and by the end face 121 of the second valve body part 112, and by bias means 96, also contained with the bore to bias the second part along the bore in a direction towards the control chamber. The bias means takes the form of a helical compression spring 131 extending along the axis 115 between the first part 111 and an end face 121' of the second part, and restraint means 135, described further hereafter, limits complete axial separation of the parts by the bias means spring.

Sensor means 88 comprises control passage means140 defined as a passage by the second part 112 between its surface 119 and the wall of the bore, being in this embodiment in the form of a region of the part removed as a substantially flat land 141 , and extending between a point 142 of the side wall thereof and the control chamber 120.

The control passage means 140 thus provides sensor signal pressure to the control chamber 120 to act on the end face 121 of part 112 that provides a displaceable chamber wall, the area of the face being such that, for a normal range of liquid pressures, the force exerted thereon by the liquid is arranged to balance the bias force with the body part 112 disposed to permit liquid flow between the inlet and outlet ducts by way of a flow passage 150, defined as a through-passage that extends substantially perpendicularly to the longitudinal axis 114 and of substantially the same cross section as the inlet and outlet ducts. The flow passage is also in communication with the control passage means 140, that is, it opens to the surface of the flat land 141. For reasons which will become apparent the width of the flat land, that is, the chord length defined on the circular section of the part, exceeds the cross-sectional width of the flow passage 150.

The control passage means, control chamber and end wall of the second valve body part thus provide in combination, sensor means and actuator means.

In addition to the bias spring 131 , the first and second parts are also able to interact by coupling means, indicated generally at 160, between them. The coupling means comprises axially overlapping, circumferentially spaced projections 161 and 162 of the first and second parts respectively, formed by removing slightly in excess of half of the circular sectional body of each part, enabling rotational manipulation of the first part between its valve-open and valve-closed orientations to be transmitted to the second part with minimal lost motion and independently of translational position of the second part.

The region 169 of the bore adjacent the first part of the valve body, and inboard of the seal 118, is connected to the drainage region 20 of the separator by way of a vent 170 and an end 171 of the first part is coupled to a handle 172 (similar to the handle 56 described above) by which the part can be manipulated between its valve-open and valve-closed positions. ln the valve-closed position, in which the first and second parts 111 and 112 are displaced 180° about the longitudinal axis from the positions shown in the Figures 2(a) to 2(d), it will be appreciated that the side wall 119 of the second body closes off the inlet duct 40' and the control passage 140 connects the control chamber to the outlet duct 40", permitting the bias spring to displace the second part to the limit of its influence with little resistance, if necessary displacing any liquid from the control chamber by way of the outlet duct.

When the first part 111 is rotated through 180° to the valve-open position, the second part 112 is rotated also and they initially assume the positions shown in Figure 2(b), with the outlet duct 40" closed by the side wall of the second part and the control passage aligned with the inlet duct 40'. The inlet duct liquid at elevated pressure flows along the control passage to the control chamber and exerts pressure on the end face 121 of the part, opposing the bias and displacing the second part towards the first part. The bias force is chosen having regard to the intended liquid supply pressure such that in response to a predetermined level of inlet duct pressure the axial displacement force exerted by the liquid on the end face positions the second part axially within the bore with the flow passage 150 in alignment with the inlet and outlet ducts, as illustrated in Figure 2(c), whereby the liquid can flow between said ducts along a minimum resistance path. It will be seen that if the supply pressure increases, its effect on the control chamber will be to displace the second part further against the bias force and beyond optimum alignment of flow passage and ducts to introduce a degree of pressure drop between inlet and outlet ducts, making the valve self-regulating against over-pressure. If the pressure rises significantly the valve body will close off the outlet duct completely. If the pressure reduces, then the first valve part is displaced by the bias means to the extent that as the flow passages leaves alignment between the inlet and outlet ducts, that is, the pressure drop in the liquid supplied to the centrifuge is greater than the drop in supply pressure per se, the centrifuge thus draws less liquid through the by-pass circuit than it would otherwise do, effecting a fast acting low pressure cut-off.

When, in normal operation that has the flow passage aligned with the inlet and outlet ducts, it is desired to close the valve, rotation of the first part 111 from the position shown in Figure 2(c) displaces the flow passage from the outlet duct and a short time later the control passage from the inlet duct. The control chamber, which contains liquid at inlet duct pressure, is thus sealed and the second part 112 is locked in its axial position against the force of the bias spring. As the rotation nears completion, the edge of the control passage comes into communication with the outlet duct, unlocking the control chamber and permitting the bias spring force to displace the second part axially, so that by the time rotation is completed the flow passage has been displaced axially from the inlet and outlet ducts, to the axial, if not rotational, position shown in Figure 2(b).

The above description of valve operation is dependant upon a defined operating condition wherein at a predetermined 'normal' supply pressure the flow passage is optimally aligned with the inlet and outlet ducts. It will be appreciated that other functional relationships may be established with respect to flow passage and ducts at 'normal' pressure which alter the characteristics of the valve in the valve-open condition

For example, and as illustrated schematically in Figure 3, the second part of the valve body 112 may be arranged to become disposed, in response to normal supply pressure, with the flow passage 150 and outlet duct 40" only partially aligned such that there is a pressure drop between them In the manner described above, an increase in supply pressure will exacerbate the mis-alignment and thus protect the pressure in the outlet duct from increase, whereas if supply pressure falls, displacement of the part by the bias means will increase alignment between the flow passage and outlet duct and produce a compensating reduction in pressure drop across the part and protect the pressure in the outlet duct from decrease until such time as the supply pressure falls below an acceptable value, at which point the dominance of the bias means effects rapid reduction in coupling between inlet and outlet ducts

Clearly such pressure drop-creating mis-alignment may be defined between the flow passage and the inlet duct or both inlet duct and outlet duct Alternatively, instead of varying pressure at the outlet duct by partially blocking the path between inlet and outlet ducts with the body part when the flow passage is out of alignment, there may be provided as illustrated schematically in Figure 4 a valve embodiment 80' including a diversion duct 190 in the valve housing to which liquid is diverted from the flow passage 150 when over-pressure displaces the second part of the valve

Figures 5(a) to 5(d) are schematic views of part of a third embodiment of the valve arrangement 80" illustrating control associated with sensing liquid pressure at the outlet duct

The component parts are similar to those of valve arrangement 80, and corresponding parts have the same reference numbers The second part of the valve body, 112', differs in that the control passage means is defined as two control passages 140i and 140₂ at opposite sides of the body part and each in communication with the flow passage 150

Figure 5(a) shows the part 112' in the valve-closed condition when displaced by the bias spring 131 with the flow and control passages out of communication with inlet duct 40', but with the control chamber 120 in communication with the outlet duct 40" by way of those passages

Figure 5(b) shows the part 112' rotated through 180° by the first part of the valve body in putting it into a valve-open position Liquid in the inlet duct flows by way of the flow passage and control passages to the control chamber 120 and acts on the end face of the part 112', overcoming the bias and displacing the part until, as shown in Figure 5(c), the flow passage is aligned with the inlet and outlet ducts to the extent chosen for 'normal' supply pressure

It will be seen from the cross-sectional view of Figure 5(d) that the circumferential extent of the control passage 140₂ is less than 140i such that when the valve body is rotated manually from the valve-open oπentation of Figure 5(c) to the valve closed orientation of Figure 5(a) the control passage 140₂ is decoupled from the inlet duct whilst the passage 140i still communicates with the outlet duct, permitting the bias spring to displace the body part 112' to the axial position shown in Figure 5(a) prior to it achieving the orientation rotationally

It will be appreciated that in the arrangements described above, the provision of control passage means in part having a greater extent in a circumferential direction than the flow passage and communicate with the ducts first, to ensure the control chamber drains and the second part moves axially before the rotation re-aligns the flow passage 150 with inlet and outlet ducts, is a consequence of the inlet and outlet ducts being 180° apart circumferentially and in line axially The above described control valve arrangements may be varied without departing from the common operating principles

For example, as indicated above, that the inlet and outlet ducts may open into the bore other than in a straight line, that is, may be displaced other that 180° circumferentially and/or may be displaced axially from each other The inlet and outlet ducts may be displaced axially with respect to each other and the flow passage inclined other than perpendicularly with respect to the longitudinal axis of the second part such that rotation of the parts though less than 360° does not effect a further alignment between the flow passage and the ducts

It will be appreciated that the control passage means may comprise a plurality of discrete passages spaced apart circumferentially of the second body, or at least opened to the side wall thereof at spaced points, such that the manipulation of the first body between valve-open and valve-closed positions is other than 180° This may be the case irrespective of whether or not the inlet and outlet ducts are 180° apart If the ducts are other than 180° apart then a single control duct may be employed and the degree of rotation between valve-open and valve-closed positions, required to align the control passage with each duct in the respective portion, varied accordingly

The control passage may be defined by one or more internal passages through the body of the second part and/or the flow passage may be defined by an external surface of the second part of the valve body Where both flow and control passages are defined by external surfaces of the second part of the valve body, they may be defined by flat or curved surfaces and, particularly where the inlet and outlet ducts are less than 180° apart, a concave surface which promotes smooth flow between them

The bias 96 means may comprise such a tension spring such as 131 within the control chamber 120 which pulls the second part away from the first part except when overcome by the force exerted by the pressure on the end face 121 of the second part Furthermore, the control chamber may be defined between the second part 112 and the first part 111 , the bias spring then comprising either a compression spring disposed between the end face 121 of the second part and the blind end 104 of the bore, or a tension spring between the first and second parts. It will be appreciated that in any event the bias means may comprise any commonly used alternative to the helical spring described.

The coupling means may take other forms, such as a plurality of interdigitated projections arrayed about the longitudinal axis, or a coaxial disposition of one part relative to the other. It will be appreciated that the coupling means is dependant upon a continuing axial overlap of the first and second parts of the valve body and as mentioned above, restraint means 135 is provided. In its simplest form this may comprise spring 131 anchored to both parts and having a natural length that ensures such overlap, or, for greater security, a flexible inextensible line 135' extending parallel to the spring.

The first part 111 of the valve body may be displaceable along the axis of the bore as well as rotatable and may be manipulated by means other than a manual lever, possibly hydraulically or, pneumatically or electromagnetically, and in such case may be totally contained within the bore rather than forming the closure.

The valve arrangement may also be configured such that the first part is displaceable, effecting valve- open and valve-closed conditions by axial rectilinear motion only, without rotation, and reflected in the form of coupling between it and the second part, wherein the alignment between the respective flow and control passages and inlet and outlet ducts is also based upon axial displacement only, or possibly with a minor degree only of rotation in response to a coupling that introduces a limited-rotation skewing motion.

Restraint means which is carried by both of the parts permits the valve body they comprise to be removed from the bore as a single entity. However, in the alternative, the restraint means may comprise radially extending and overlapping projections on the respective parts such as shown ghosted at 135" in Figure 2(b) which avoid separation of the projections of the coupling means within the bore. Such restraint means may, alternatively, comprise or include a stop extending from the blind end of the bore as shown ghosted at 135'" of that Figure.

As outlined above the sensor means and actuator means may be other than a direct supply of liquid that is, in passing through the valve, caused to apply a pressure-related force to part of the valve body displaceable by translation or otherwise. A separate fluid-or electrically-powered actuator may dispose the displaceable part, or all, of the valve body in accordance with signals from discrete sensors of duct pressure or flow rate and such actuation may be arranged to move the valve body bi-directionally and without bias means. However, an arrangement which follows the approaches of the embodiments detailed above is both compact and cost effective to implement in relation to a centrifugal separator of the mass-produced types used with vehicle engines. ln relation to any implementation of the present the term "manually movable" in relation to a part of the valve body means is intended to include movement under manual control, and includes a body part which is connected to any actuator that is controlled remotely from the valve body itself.

Claims

1. A control valve arrangement (80; 80'; 80") for a self-powered centrifugal separator (15'), comprising a valve housing (17) containing a valve space (82, 102), an inlet and an outlet duct (40', 40") each opening into a wall of the valve space and arranged respectively to deliver liquid at elevated pressure to, and lead it from, the valve space, valve body means (84), disposed in the valve spacing, arranged to control the flow between the inlet and outlet ducts, and characterised by valve control means comprising sensor means (88), disposed in the centrifugal separator, operable to provide a sensor signal representing a value of a parameter of the liquid, and valve body positioning means (90) operable in response to said sensor signal to set the disposition of at least a part (112) of the valve body means to attempt to maintain said parameter of liquid led from the valve space within a predetermined range of values.

2. A control valve arrangement as claimed in claim 1 characterised in that the valve body means (90) is displaceable within the housing under manual control between a valve-closed state, in which the valve body means prevents liquid flow between said inlet and outlet ducts, and a valve-open state, in which said disposable part is displaceable by said control means in response to said sensor signal.

3. A control valve arrangement as claimed in claim 1 or] claim 2 characterised in that the parameter of the liquid is pressure and the sensor means is arranged to provide a sensor signal representative of the pressure of said liquid.

4. A control valve arrangement as claimed in any one of claims 1 to 3 characterised in that the valve body positioning means (90) comprises bias means (96) operable to bias said displaceable valve body part (112) in a direction towards a predetermined disposition within the housing and actuator means (94) operable to act on said part to displace it in opposition to the bias means in accordance with the level of the sensor signal.

5. A control valve arrangement as claimed in claim 4 when dependant on claim 2 characterised in that, in the valve-closed state, the displaceable valve body part (112) is arranged to be disposed by the bias means to prevent said liquid flow between inlet and outlet ducts.

6. A control valve arrangement as claimed in claim 4 or claim 5 when dependent on claim 3 characterised in that the sensor means (88) comprise control passage means (140; 140_!, 140₂) arranged, in said valve-open state, to provide liquid communication between a said duct and the actuator means (94).

7. A control valve arrangement as claimed in claim 6 characterised in that the actuator means (94) comprises a control chamber (120) defined in the valve space between a closed-end thereof (104) and a displaceable part of the valve body means (112), said displaceable valve body part comprises a displaceable chamber wall (121) having an area on which said sensor signal pressure acts with a force arranged to balance the bias with the body part disposed to permit liquid flow between the inlet and outlet ducts.

8. A control valve arrangement as claimed in claim 7 characterised in that the displaceable part of the valve body means (112) is translatable along the valve space.

9. A control valve arrangement as claimed in claim 8 characterised in that said translatable part of the valve body means has side walls (119) facing the wall of the valve space and end walls (121, 121') facing along the valve space, one of said end walls (121) defining the displaceable wall of the control chamber (120), and a flow passage (150) extending from one side of the part to the other, and arranged to connect the inlet and outlet ducts at a predetermined translational disposition of the part, and the bias means (96) is arranged to bias the translatable part (112) along the valve space in a direction towards the control chamber that disposes the flow passage out of alignment with the inlet and outlet ducts.

10. A control valve arrangement as claimed in claim 9 characterised in that which the control passage means (140; 140,; 140₂) is defined by the translatable part between a point on the side wall thereof and the control chamber, and in communication with the flow passage.

11. A control valve arrangement as claimed in any one of claims 7 to 10 characterised in that the valve space 102) extends from a first, actuation end (103), to a second, blind end (104), defining said control chamber (120), the valve body means (84) comprising a manual control part (111) disposed at the actuation end of the valve space and displaceable between a valve-open position, defining the valve-open state, and a valve-closed position, defining the valve-closed state, and said translatable part (112) disposed between the manual control part and the blind end of the valve space, coupling means (160) between the manual control part and translatable part of the valve body, said coupling means being operable, in response to manipulation of the manual control part to said valve-open position, to dispose the translatable part with the flow passage (150) axially displaced from alignment with the inlet and outlet ducts to permit liquid at inlet duct pressure to enter the control chamber (120) and permit a predetermined level inlet duct pressure to exert an axial displacement force on said translatable part in opposition to the bias means to position the translatable part within the bore with the flow passage in axial alignment with the inlet and outlet ducts, and operable in response to manipulation of the manual control part (111) to said valve- closed position to dispose the translatable part with the flow passage out of communication with the inlet duct and with the control passage means in communication with the outlet duct and permit the bias means to effect axial displacement of the flow passage from said axial alignment with the inlet and outlet ducts.

12. A control valve arrangement as claimed in claim 11 characterised in that the valve space (82) comprises a bore (102) in the valve housing, said bore and said valve body parts (111, 112) are circular in section and said parts are rotatable within the bore about a common longitudinal axis (115), the manual control part (111) being rotatable about said axis between the valve-open and valve-closed positions and the translatable part (112) being also rotatable within the bore by way of said coupling means (160).

13. A control valve arrangement as claimed in claim 12 characterised in that the manual control part (111) is substantially fixed axially in relation to the bore (102) and arranged to form a closure for the bore at said actuation end.

14. A control valve arrangement as claimed in claim 12 or claim 13 characterised in that which a portion (171) of the manual control part (111) extends from the bore and is adapted for manual displacement to effect said manipulation between the valve-open and valve-closed positions.

15. A control valve arrangement as claimed in any one of claims 12 to 14 characterised in that the coupling means (160) comprises axially overlapping, circumferentially spaced projections (161, 162) of the valve body parts.

16. A control valve arrangement as claimed in any one of claims12 to 15 characterised in that the bias (96) means comprises compression spring means (131) extending along the valve space.

17. A control valve arrangement as claimed in claim 16 when dependent on claims 11 to 15 characterised in that the compression spring means (131) extends between the manual control part (111) and the translatable part (112) at an end face (121') of the translatable part opposite to said end face which defines said control chamber.

18. A control valve arrangement as claimed in any one of the preceding claims including restraint means (135'; 135") carried by the valve body means operable to limit translational separation between parts of the valve body means.

19. A control vaive arrangement as claimed in claim 6 or any claim dependent thereon characterised in that the control passage means (140; 140,, 140₂) is defined between the surface of the translatable part (119) and the wall of the valve space.

20. A self-powered centrifugal separator of solid contaminants from a liquid lubricant, adapted to be operably mounted against a substantially horizontal mounting surface of a machine in which said liquid lubricant is circulated by pumping from a reservoir, the centrifugal separator comprising i) a base (17) having a first surface thereof (18) adapted to be mounted in an operable disposition against a said mounting surface of a machine and a second surface (19) arranged with respect to said first surface to lie, with said first surface so mounted, to be generally upwardly facing, ii) a liquid drain passage (21) extending through the base from a collection region

(20) in said second surface to a surface (18) other than the second surface, iii) spindle means (25) extending from said second surface of the base along an operably substantially vertical axis above the collection region and containing an axially extending spindle passage (27), iv) a rotor (30), supported on the spindle means for rotation thereabouts, having an annular contaminant container (32) in communication with the spindle passage and, by way of reaction nozzle means (34), with the collection region, said annular contaminant container being operable in response to receipt of said pumped liquid lubricant from the spindle means at elevated pressure and ejection thereof from the reaction nozzle means to effect rotation about the spindle means at such speed as to separate said solid contaminants from the liquid lubricant within the contaminant container, v) a removable cover (35) supported on the base and enclosing the rotor and collection region, vi) a liquid lubricant supply duct (40) extending through the base between said spindle passage and a surface other than said second surface, and vii) a control valve arrangement as claimed in any one of the preceding claims formed within the base (17) as a valve housing.