GB2412713A

GB2412713A - Fluid control

Info

Publication number: GB2412713A
Application number: GB0407076A
Authority: GB
Inventors: D Coley
Original assignee: Aldridge Piling Equipment Hire Co Ltd
Current assignee: Aldridge Piling Equipment Hire Co Ltd
Priority date: 2004-03-30
Filing date: 2004-03-30
Publication date: 2005-10-05
Anticipated expiration: 2024-03-30
Also published as: GB0407076D0; GB2412713B

Abstract

A fluid control arrangement 10 has a nozzle 12 through which pressurised fluid 14 leaves to cross a chamber 36. Part of the nozzle surface 16 is provided by a rotating cylinder 26 having different surface properties around its perimeter, so that rotation causes the surface properties at 16 to change. This, in turn, changes the angle through which the jet 42 leaves the nozzle 12, allowing the upper or lower outlets 38 to be selected, thus forming a valve arrangement.

Description

Fluid Control The present invention relates to fluid control and in

particular, but not exclusively, to fluid control arrangements for use in valves and actuators.

Control of fluid, particularly pressurised fluid, is required in many situations, such as those in which actuator cylinders are driven by pressurised fluid to operate various types of machinery. Typically, a valve arrangement is used to control the supply of pressurized fluid to the actuator. Various flow paths are therefore required through the valve, for pressurized fluid, and for return fluid. This creates various problems arising from the need to provide adequate seals or other separation between the paths for pressurized and returned fluid, particularly as a single path may be used,or both purposes, at different points in an operating cycle.

Some valve designs, such as servo valves, incorporate sophisticated electronic control arrangements. This introduces additional complexity and vulnerability to breakdown.

The present invention provides a fluid control arrangement comprising: a nozzle through which pressurised fluid leaves the arrangement, during use, at least one nozzle surface which at least in part defines the nozzle, and in which the said nozzle surface has a surface property which is selectively changeable, while fluid is flowing through the nozzle, in use, to change the local velocity of fluid across the surface and thereby change the direction at which fluid leaves the nozzle.

The arrangement may further comprise means operable to sequentially change the surface property.

Preferably the said surface is provided by a part of the surface of a control member which is moveable to present different surface parts to the pressurised fluid, the different surface parts having different surface properties.

The arrangement may comprise a fixed nozzle surface having a gap through which the control member is exposed to the pressurised fluid. The control member may be rotatable to present different surface parts, as aforesaid. The control member may be an axially rotatable cylinder.

The changeable surface property preferably affects the velocity of fluid across the said surface. The changeable surface property may be the coefficient of friction, the surface shape, surface texture, roughness, smoothness, porosity or material. The changeable surface property is preferably selectable to match the surface property of at least one other surface which partly defines the nozzle.

The arrangement may form part of a valve arrangement having at least one outlet port separated from the nozzle, and to which pressurised fluid leaving the nozzle is selectively directable, in use. The valve arrangement may comprise a drain for pressurised fluid which does not enter the or an outlet port.

The nozzle and the outlet port may be separated by means of a chamber across which a jet of pressurised fluid may flow from the nozzle to an outlet port, when selected, and from which fluid may drain.

The valve arrangement preferably comprises a plurality of nozzles as aforesaid. The nozzles may be operable to direct pressurised fluid to at least one common outlet port. Alternatively, each nozzle may be associated with a respective outlet port to select whether or not pressurised fluid leaves the associated outlet port. The nozzles may be controlled together to cause fluid alternately to leave respective outlet ports.

In a second aspect, the invention provides a valve arrangement comprising: an inlet nozzle through which pressurized fluid enters the valve arrangement, a chamber into which pressurized fluid enters, in use, as a jet from the inlet nozzle, at least one outlet nozzle to receive the jet after crossing the chamber, and direction means operable to selectively change the direction of the jet from the inlet nozzle, to be selectively directed to the or a selected outlet 1 5 nozzle.

The inlet nozzle is preferably defined, at least in part, by a nozzle surface having a surface property which is selectively changeable to change the direction at which fluid leaves the nozzle.

The arrangement may comprise a fixed nozzle surface having a gap through which the control member is exposed to the pressurised fluid. The control member may be rotatable to present different surface parts, as aforesaid. The control member may be an axially rotatable cylinder. l

Alternatively, the inlet nozzle may be defined by a member which is selectively moveable to re-direct the jet. The moveable member may define a passage whose orientation determines the jet direction and is changed b movement of the moveable member. The moveable member may be rotatable about a rotation axis, and have a nozzle mouth positioned eccentrically relative to the rotation axis. The moveable member may be an axially rotatable cylinder having end faces and a passage for pressurized fluid between the end faces. The passage may have an inlet centered at the axis, and an eccentric outlet.

In a third aspect, the invention provides an actuator, comprising: an actuator cylinder, a piston moveable within the cylinder by pressurized fluid, and a valve arrangement to supply pressurized fluid to the cylinder to move the piston, the valve arrangement being in accordance with the second aspect of the invention and supplying pressurised fluid from the or each outlet nozzle to the cylinder.

Various embodiments of the present invention wil' now be described in more detail, by way of example only, and with reference to the accompanying drawings, in which: Fig. 1a is a schematic section through a valve arrangement according JO to the present invention, and Fig. 1b is an elevation of the nozzle of the arrangement of Fig. 1 a; Figs. 1 c and 1 d correspond with Figs. 1 a and 1 b, showing an alternative condition of the arrangement; Fig. 1 e is an enlarged part of Fig. 1 b, showing the control member; Figs. 1f and 19 are schematic diagrams of the valve arrangement of Fig. 1 a, in use to control an actuator; Figs. 2a to 2f correspond with Figs. 1a to 1d, 1f and 1g, respectively, and show an alternative arrangement; and Figs. 3a and 3b are schematic diagrams of an alternative arrangement in use to control an actuator.

The drawings of Fig. 1 illustrate a first fluid control arrangement and an example of its application as part of a valve arrangement for controlling an actuator.

The fluid control arrangement indicated generally at 10 has a nozzle 12 through which pressurized fluid (indicated at 14) leaves, during use. The \ arrangement 10 has a nozzle surface 16 which at least in part defines the nozzle 12. The surface 16 has a surface property which is selectively changeable, as will be described. This causes the flow of the fluid 14 through the nozzle 12 to change, resulting in a change in the direction at which fluid leaves the nozzle 12, as can be seen by comparison of Figs. 1 a and 1 c.

In more detail, the nozzle 12 is formed at the end of a passage 18 through a body 20. Pressurised fluid 14 is delivered to the nozzle 12 through the passage 18, as indicated by the arrowheads 22. The final leg 24 of the passage 18 is straight (as can be seen from Figs.1 a and 1 c) and substantially circular in section (as can be seen from Figs. lb and Ed). Almost all of the circumference of the passage 18 is defined by fixed surfaces of the body 20, but at the bottom of the passage 18 (as seen in Figs.1 b and 1 d) a longitudinal gap 25 exists between the edges of the fixed passage walls (Fig. 1e). This gap 25 is closed by a control member 26.

The control member 26 is a circular cylinder located within the body 20 with its axis parallel to the axis of the final leg 24 of the passage 18.

Accordingly, the control member 26 closes the gap 25 along the whole length of the final leg 24. The control member 26 is rotatably received within the body 20. A motor 28 is coupled to the control member 26 to drive the control member 26 for rotation about its axis.

Attention must now be drawn to the surface of the control member 26.

In this example, the surface is divided into two semi-cylindrical surfaces.

These have different surface properties. In particular, one semicylindrical surface 30 (shown uppermost in Fig. 1 e) is smooth relative to the other semi cylindrical surface 32 shown lowermost in Fig. 1e, which is relatively rough.

Consequently, when the control member 26 is in the position illustrated in Fig. 1 e, the gap 25 is closed by a length of the smooth semi-cylindrical surface 30.

If the control member 26 is turned about its axis, by operation of the motor 28, the gap 25 will initially remain closed by the smooth surface 30, until the control member 26 has turned sufficiently to result in the rough surface 32 entering the gap 25. Thus, successive half rotations of the control member 26 will correspond, alternately, with the smooth surface 30 and the rough surface 32 being received within the gap 25. Thus, the nozzle surface provided by the control member 26 within the gap 25 has a surface property which is selectively changeable by rotation of the control member 26 about its axis. It is important to note that this arrangement allows the surface property to be changed while the nozzle is in use, by simple rotation of the control member 26.

The significance of this can now be described, after first describing the other features present in the arrangement of Figs. 1 a and 1 c.

The fluid control arrangement 10 forms part of a valve arrangement 34.

This includes a chamber 36 to which the nozzle 12 forms an inlet and which has upper and lower outlets 38. The chamber 36 is also drained at 40 to a reservoir from which pressurized fluid is drawn for supply to the passage 18.

In Figs. 1 a and 1 b, the control member 26 presents the smooth surface to the fluid 14, through the gap 25. Preferably the smoothness of the surface 30 matches the smoothness of the fixed walls of the passage 18.

Consequently, the fluid 14 flows smoothly along the passage 18, leaving the nozzle 12 as a jet at 42, which leaves the nozzle 12 without significant turbulence, and travels straight across the chamber 36 to enter the upper outlet 38. Thus, with the control member 26 in this orientation, the fluid 14 is directed to the upper outlet 38. Lack of turbulence may be further enhanced by providing a projection into the passage 18, diametrically opposite the member 26, to ensure symmetry in the shape of the passage.

If the control member 26 is now rotated until the rough surface 32 is presented to the fluid 14 through the gap 25, the increased roughness will cause drag on the fluid 14 as it moves across the surface 32, resulting in localised turbulence and reduced flow velocity. This disturbs the fluid 14 leaving the nozzle 12, in part by virtue of the reduced velocity, causing the jet 42 to bend down, away from the upper outlet 38. By appropriate positioning of the upper and lower outlets 38, and choice of the surface properties of the surfaces 30, 32, the arrangement can be as shown in Figs. 1 a and 1c, namely that the presence of the smooth surface in the gap 25 directs the jet 42 to the upper outlet 38, whereas the presence of the rough surface 32 in the gap 25 causes the jet 42 to bend down to enter the lower outlet 38. Consequently, the arrangement 34 is acting as a valve, allowing rotation of the control member 26 to selectively change over the valve, so that a continuous stream of fluid can be switched, as required, to leave a selected outlet 38.

The valve arrangement just described can be used for controlling an actuator, as can now be described with reference to Figs. 1f and 1g. In Fig. 1f, the valve arrangement 34 is in the condition of Fig. 1a, with the smooth surface 30 exposed in the gap 25. This directs fluid to the upper outlet 38a, which is in turn connected by an upper passage 44 to a chamber 46. A piston 48 is located in the chamber 46. Fluid from the upper passage 44 enters the chamber 46 above the piston 48, having the result of driving the piston down, as illustrated in Fig. 1f.

In the alternative condition of the valve arrangement 34, fluid leaves the valve through the lower outlet 38b and passes through a lower passage to the chamber 46, beneath the piston 48, so that in this valve condition, the piston 48 is driven upwardly.

Consequently, continued rotation of the control member 26 results in fluid being alternately supplied above and below the piston 48, resulting in the piston reciprocating. I 5

As the piston 48 reciprocates, one or other face of the piston will exhaust spent fluid back to the chamber 36, through the respective passage 44, 50. Since this fluid will be at return pressure, no jet will be formed back to the nozzle 12. Rather, the return fluid will fall into the chamber 36 and be carried away through the drain 40.

The piston may be a spool of a further valve arrangement which in turn drives a larger actuator, so that the valve arrangement of the invention is providing servo-like or second stage control of the spool, which is, in turn, controlling the larger actuator.

In an alternative arrangement (not illustrated), the valve arrangement may be provided with a single outlet 38 and a drain 40, so that rotation of the control member 26 causes pressurised fluid either to leave through the outlet 38, or to drain away at 40. In a further alternative (not illustrated) a piston and chamber 48, 46 of the type shown in Figs. 1f and 1g could be controlled by two valves of this nature, one responsible for supplying fluid to raise the piston 48, and the other being responsible for supplying fluid to return the piston 48, the two valves being coordinated to create reciprocation of the piston 48.

In a further alternative (not illustrated), multiple nozzles could be provided within a common chamber, each operable to direct pressurised fluid to a common outlet port, or each operable to direct pressurised fluid to a respective outlet port.

It will be apparent from an understanding of the above description that although the outlet ports have been described as upper and lower, the particular angles at which they leave the chamber 36 can be varied according to the geometry of the nozzle and chamber, and according to the surface characteristics of the surfaces 30, 32. In addition, the interference with the fluid flow could be used to deflect the jet 42 sideways, rather than up and down, or in other directions.

Fig. 2 illustrates the possibility of two valves being used to control opposite movements of a piston. Many features of Fig. 2 correspond with features described in relation to Fig. 1 and are given the same reference numerals, suffixed a.

In Fig. 2, a single body 20a is provided with two control arrangements 10a, each of the type described above in relation to Fig. 1, and having respective nozzles 12a into a common chamber 36a. Each nozzle 12a is associated with a corresponding outlet 52. The nozzles 12a are supplied with pressurised fluid through respective passages 18a, fed from a common supply at 54. The control members 26a of the arrangements 10a are both driven by a common motor 28a to ensure synchronization between the positions of the control members 26a.

Each of the control members 26a is used to control the respective nozzle 12a so that either, a jet 42a is directed across the chamber 36a from the respective nozzle 12a to the associated outlet 52, or alternatively, fluid 14a leaves the nozzle 12a, falls into the chamber 36a and leaves through the drain 40a. Again, the flow of pressurised fluid may be continuous through each nozzle 12a, so that immediately one jet is switched away from the corresponding outlet, the other jet may be switched to the respective corresponding outlet.

The control members 26a are used to control the arrangements 10a out of phase, so that at any one time, one arrangement 1 Oa will be directing a jet 42a to the associated outlet 38, while the other arrangement 10a is draining through the chamber 36a. The arrangements 10a then reverse, so that the other arrangement creates a jet 42a to the associated outlet 38, and the first arrangement 10a drains through the chamber 36a. The two situations are illustrated in Figs. 2a and 2c. Figs. 2b and 2d show the positions of the control members 26a, in the two conditions illustrated in Figs. 2 a and 2c.

Consequently, the arrangement forms a more complex valve arrangement allowing a continuous flow of pressurized fluid 14a to be directed from the common supply 54 to a selectable outlet 52, the other outlet 52 being connected to the drain 40a through the chamber 36a.

Accordingly, the arrangement can be used as a control valve arrangement 34a for controlling a piston 48a in a chamber 46a, by connecting one of the outlets 52 to each side of the piston 48a, so that as the valve arrangement 34a alternately directs fluid 14a to the outlets 52, the piston 48a is caused to reciprocate. Again, the piston 48a may be an actuator or the spool of a servo-like or second stage valve.

In the arrangements of Fig. 2, jets 42a from the two arrangements 1 Oa both cross a common chamber 46a. In an alternative, the arrangement of Fig. 2 can be modified to provide separate chambers for each jet 42a. In a further alternative to those described above, the arrangements 1 Oa may be arranged so that they both direct their respective jets 42a to one or other outlet 52, simultaneously and selectively. This avoids pressurised fluid being wasted to the drain.

The arrangements so far described have all controlled the pressurised fluid by means of surface properties and their effect on flow velocity. Fig. 3 illustrates an alternative arrangement.

Fig. 3 illustrates a valve arrangement 60 formed within a body 62. A chamber 64 is formed within the body 62. Pressurised fluid supplied at 66 enters the chamber 64 as a jet from a nozzle 68, to cross the chamber 64 to one of the outlet nozzles 70, which is selectable, as will be described. The chamber 64 is drained at 72.

The nozzle 68 is provided in a manner which allows the direction of the jet 74, leaving the nozzle 68, to be selectively changed. In this example, the nozzle 68 is formed as a circular cylindrical block which is rotatable about its axis 76, being driven by a motor 78. A passage 80 extends from one end face 82, through the block 75 to the other end face 84. It is to be noted that the passage 80 is not parallel with the axis 76, but is centered at the axis 76 at the end face 82, being eccentric relative to the axis 76 at the end face 84.

Consequently, appropriate seal arrangements at the face 84 allow fluid to be supplied continuously to the passage 80 while the block is rotating.

Consequently, as the block 75 rotates about the axis 76, a first position is reached (Fig. 3a) in which the passage 80 directs the jet 74 to a first outlet 70. Further rotation of the block 75 results in the position of Fig. 3b, in which the passage 80 directs the jet 74 to the other outlet 70. Consequently, by rotation of the block 75, the continuous jet 74 from the inlet nozzle can be selectively directed to a selected outlet nozzle 70. This allows the arrangement to be used to control a reciprocating piston 86, by connecting the outlets 72 to a chamber 88, to either side of a piston 86. The piston 86 may be an actuator or the spool of a servo-like or second stage valve.

Many variations and modifications can be made to the apparatus described above, without departing from the scope of the present invention.

In particular, many different geometries can be devised for the arrangements described, taking into account methods and materials of manufacture, and their properties, the pressure and nature of the fluid to be controlled, and other environmental factors.

Whilst endeavouring in the foregoing specification to draw attention to those features of the invention believed to be of particular importance it should be understood that the Applicant claims protection in respect of any patentable feature or combination of features hereinbefore referred to and/or shown in the drawings whether or not particular emphasis has been placed thereon.

Claims

CLAI MS

1. A fluid control arrangement comprising: a nozle through which pressurised fluid leaves the arrangement, during use, at least one nozle surface which at least in part defines the nozle, and in which the said nozle surface has a surface property which is selectively changeable, while fluid is flowing through the nozle, in use, to change the local velocity of fluid across the surface and thereby change the direction at which fluid leaves the nozle.

2. A fluid control arrangement comprising: a nozle for projection of a pressurised fluid, a nozle surface which defines at least a part of the nowle, and the said nozle surface has a changeable surface property which in use is selectively changeable, relative to a fluid flowing through the nozle, to change the local velocity of fluid across the nozle surface relative to the remainder of the fluid and thereby change the projection direction at which fluid leaves the nozle.

3. An arrangement as claimed in claim 1 or claim 2 wherein the arrangement may further comprise means operable to sequentially change the surface property.

4. An arrangement as claimed in any of claims 1, 2 or 3 wherein the said surface is provided by a part of the surface of a control member which is moveable to present different surface parts to the pressurised fluid, the different surface parts having different surface properties.

5. An arrangement as claimed in any preceding claim wherein the arrangement may comprise a fixed nozle surface having a gap through which the control member is exposed to the pressurised fluid.

6. An arrangement as claimed in claim 4 and claim 5 when dependent on claim 4 wherein the control member may be rotatable to present different surface parts.

JO

7. An arrangement as claimed in claim 4 and any claim dependent thereon wherein the control member may be an axially rotatable cylinder.

8. An arrangement as claimed in any preceding claim wherein the changeable surface property affects the velocity of fluid across the said l 5 surface.

9. An arrangement as claimed in any preceding claim wherein the changeable surface property may be the coefficient of friction, the surface shape, surface texture, roughness, smoothness, porosity or material.

10. An arrangement as claimed in any preceding claim wherein the changeable surface property is selectable to match the surface property of at least one other surface which partly defines the nozle.

11. An arrangement as claimed in any preceding claim wherein the arrangement may form part of a valve arrangement having at least one outlet port separated from the nozle, and to which pressurised fluid leaving the nozle is selectively directable, in use.

12. An arrangement as claimed in claim 11 wherein the valve arrangement may comprise a drain for pressurised fluid which does not enter the or an outlet port.

13. An arrangement as claimed in claim 11 or claim 12 wherein the nozle and the outlet port may be separated by means of a chamber across which a jet of pressurised fluid may flow from the nozle to an outlet port, when selected, and from which fluid may drain.

14. An arrangement as claimed in any of claims 1 1 to 13 wherein the valve arrangement comprises a plurality of nozles.

JO

15. An arrangement as claimed in claim 14 wherein the nozles may be operable to direct pressurised fluid to at least one common outlet port.

16. An arrangement as claimed in claim 14 wherein each nozle may be associated with a respective outlet port to select whether or not pressurised fluid leaves the associated outlet port.

17. An arrangement as claimed in any of claims 14 to 16 wherein the nozles may be controlled together to cause fluid alternately to leave respective outlet ports.

18. A fluid control arrangement substantially as hereinbefore described with reference to the accompanying drawings.

19. A valve arrangement comprising: an inlet nozle through which pressurised fluid enters the valve arrangement, a chamber into which pressurised fluid enters, in use, as a jet from the inlet nozle, at least one outlet nozle to receive the jet after crossing the chamber, and direction means operable to selectively change the direction of the jet from the inlet nozle, to be selectively directed to the or a selected outlet nozle.

20. A valve arrangement as claimed in claim 19 wherein the inlet nozle is defined, at least in part, by a nozle surface having a surface property which is selectively changeable to change the direction at which fluid leaves the nozle.

21. An arrangement as claimed in claim 19 or claim 20 wherein the arrangement may further comprise means operable to sequentially change the surface property.

22. An arrangement as claimed in any of claims 19 to 21 wherein the said surface is provided by a part of the surface of a control member which is moveable to present different surface parts to the pressurised fluid, the different surface parts having different surface properties.

23. An arrangement as claimed in any of claims 19 to 22 wherein the arrangement may comprise a fixed nozle surface having a gap through which the control member is exposed to the pressurised fluid.

24. An arrangement as claimed in any of claims 19 to 23 wherein the control member may be rotatable to present different surface parts.

25. An arrangement as claimed in claim 24 wherein the control member may be an axially rotatable cylinder.

26. An arrangement as claimed in any of claims 19 to 25 wherein the changeable surface property affects the velocity of fluid across the said surface.

27. An arrangement as claimed in any of claims 19 to 26 wherein the changeable surface property may be the coefficient of friction, the surface shape, surface texture, roughness, smoothness, porosity or material.

28. An arrangement as claimed in any of claims 19 to 27 wherein the changeable surface property is selectable to match the surface property of at least one other surface which partly defines the nowle.

l O

29. An arrangement as claimed in any of claims 19 to 28 wherein the inlet nozzle may be defined by a member which is selectively moveable to re-direct the jet.

30. An arrangement as claimed in claim 29 wherein the moveable member may define a passage whose orientation determines the jet direction and is changed by movement of the moveable member.

31. An arrangement as claimed in claim 29 or 30 wherein the moveable member may be rotatable about a rotation axis, and have a nozzle mouth positioned eccentrically relative to the rotation axis.

32. An arrangement as claimed in claim 31 wherein the moveable member may be an axially rotatable cylinder having end faces and a passage for pressurised fluid between the end faces.

33. An arrangement as claimed in claim 31 or claim 32 wherein the passage may have an inlet centered at the axis, and an eccentric outlet.

34. A valve arrangement substantially as hereinbefore described with reference to the accompanying drawings.

35. An actuator, comprising: an actuator cylinder, a piston moveable within the cylinder by pressurised fluid, and a valve arrangement to supply pressurised fluid to the cylinder to move the piston, the valve arrangement being in accordance with the second aspect of the invention and supplying pressurised fluid from the or each outlet nozle to the cylinder.

36. An actuator as claimed in claim 35 wherein the valve arrangement comprises a plurality of nozles.

37. An actuator as claimed in claim 35 or claim 36 wherein the nozles may be operable to direct pressurised fluid to at least one common outlet port.

38. An actuator as claimed in claim 35 or claim 36 wherein each nozle may be associated with a respective outlet port to select whether or not pressurised fluid leaves the associated outlet port.

39. An actuator as claimed in any of claims 35 to 38 wherein the nozles may be controlled together to cause fluid alternately to leave respective outlet ports.

40. An actuator substantially as hereinbefore described with reference to the accompanying drawings.

41. Any novel subject matter or combination including novel subject matter disclosed herein, whether or not within the scope of or relating to the same invention as any of the preceding claims.