WO2012032297A1

WO2012032297A1 - Fluid flow control devices with rotary coupling

Info

Publication number: WO2012032297A1
Application number: PCT/GB2011/001318
Authority: WO
Inventors: Stephen Paul Hill; Peter James Hamer
Original assignee: Bifold Fluidpower Limited
Priority date: 2010-09-11
Filing date: 2011-09-08
Publication date: 2012-03-15
Also published as: EP2614284A1; GB2486394A; GB2486394B; GB201015176D0

Abstract

An assembly comprising a first fluid flow control device (27) coupled to a second fluid flow control device (25). The first fluid flow control device has a body with a first fluid passage and the second fluid flow control device has a body with a second fluid passage, the first and second fluid passages being in fluid communication to form a first fluid path. The first and second fluid flow control devices are coupled together by means of a rotary coupling comprising a first coupling part and a second coupling part defining mutually co-operating guide surfaces for supporting relative rotation of the first and second fluid flow control devices. The first coupling part (56) is provided by the first fluid control device is penetrated by at least part of the first fluid passage. The second coupling part connected to one of the first and second fluid flow control devices and comprises a releasable clamping member (28) for movement between a first position in which the first and second fluid flow control devices are rotatable relative to one another about a rotational axis and a second position in which it clamps against a clamping surface of the other of the first and second fluid flow control devices so as to clamp the devices against relative rotation in at least one selected position.

Description

Fluid Flow Control Devices with Rotary Coupling

The present invention relates to fluid flow control devices and in particular to the coupling of two or more such devices together by means of a rotary coupling. The invention relates particularly, but not exclusively, to the coupling of pneumatic control devices such as directional control valves to other pneumatic circuit components or to an actuator for a pipeline valve or the like.

Large valves, and those in remote or difficult to access locations, are generally operated by means of an actuator. The operation of, for example, a ball valve in an offshore gas or petro-chemical pipeline is often effected by a valve positioner that provides fluid (typically pneumatic) signals to the actuator for operating the valve. The actuator comprises a piston and cylinder arrangement which can take several forms. For example, in one actuator type the piston divides the actuator cylinder into a pair of chambers at least one of which may be selectively pressurised by the introduction compressed air in order to move the piston and operate the valve. A shaft of the piston is linked mechanically to a stem of the ball valve so that its movement in the cylinder effects rotation of the valve. In a single-acting piston, the other chamber is occupied by a biasing member such as a spring against which the pressurised air acts. When the pressurised air supply drops below a certain value the force applied by it to one side of the piston is less than that applied on the other side by the spring in which case the pressurised air is exhausted from the cylinder. In a double-acting piston air is selectively supplied to one of the chambers and simultaneously exhausted from the other.

The pressurised air is generally supplied to the actuator to advance the piston within the cylinder via a pneumatic supply circuit, including one or more directional fluid control valves that control the supply of air to and from the actuator. Exhaust air from the actuator can be directed through the control valve(s) in the supply circuit in which case the flow rate may be restricted or, alternatively, a quick exhaust valve may be used. This particularly desirable when there is an emergency that requires actuator to close the pipeline valve as quickly as possible.

The positioner and the directional fluid control valves are generally supported on mounting surfaces defined on the exterior of the actuator cylinder, the surfaces typically having a Namur standard interface in which the positions and sizes of the ports and mounting bores conform to a standard. For the interface with the directional fluid control valve there are two ports for air communication with respective chambers on each side of the piston and fixing apertures to which the control valves are fixed. Other devices such as a valve position indicator or a pressure gauge may also be mounted to the actuator housing. The pneumatic control circuit may comprise several directional fluid control valves, a quick exhaust valve, a filter regulator and other items connected together in a stack or block and there is often physical interference between components of the control circuit and the valve positioner or other devices which can only be solved by introducing bespoke adapters to change flow paths and orientation of various devices. In many circumstances space is at a premium and there is a requirement to provide a more versatile or flexible manner of arranging the pneumatic control circuit components.

Moreover some pneumatic control circuit components with integral drain features (such as, for example, filter regulators) rely upon gravitational forces for their correct function and should be mounted vertically in order for them to perform effectively.

It is an object of the present invention to obviate or mitigate the above, or other, disadvantages. It is also an object of the present invention to provide for an improved, or alternative, arrangement of fluid flow control devices

According to the present invention there is provided a first fluid flow control device coupled to a second fluid flow control device, the first fluid flow control device having a body with a first fluid passage and the second fluid flow control device having a body with a second fluid passage, the first and second fluid passages being in fluid communication to form a first fluid path, the first and second fluid flow control devices being coupled together by means of a rotary coupling comprising a first coupling part and a second coupling part defining mutually co-operating guide surfaces for supporting relative rotation of the first and second fluid flow control devices, the first coupling part provided by the first fluid control device and being penetrated by at least part of the first fluid passage, the second coupling part connected to one of the first and second fluid flow control devices and comprising a releasable clamping member for movement between a first position in which the first and second fluid flow control devices are rotatable relative to one another about a rotational axis and a second position in which it applies a clamping force against a clamping surface of the other of the first and second fluid flow control devices so as to clamp the devices against relative rotation in at least one selected position.

At least one of the first and second fluid flow control devices may be a directional fluid control valve. At least one of the first and second fluid control devices may be a fluid pressure regulator which may include a fluid filter. The directional control valve may comprise a valve body into which one of the first and second fluid passages extends. There may be further devices directly or indirectly attached to the directional control valve for rotation therewith such as, for example, further directional control valves, a quick exhaust valve, a check valve, a filter regulator, a pressure relief valve, or a volume booster.

The clamping force may be applied directly or indirectly through at least one intermediate member.

The first and second fluid flow control devices may be clamped together at a finite or infinite number of selected positions. The first and second fluid flow control devices may be pneumatic control devices that comprise all or part of a pneumatic control circuit.

The body of the first and/or second fluid flow control device may be substantially rectangular or square in cross-section. It may be substantially parallelepiped.

There may be an intermediate body between the first and second fluid flow control devices. For example, the intermediate body may be an adapter plate that is penetrated by bores for ensuring fluid communication between the devices. Such an intermediate body is connected to one of the first and second devices and effectively becomes part of that first or second device.

The rotational axis may be substantially coincident with the centre of the part of the first fluid passage that penetrates the first fluid coupling part.

The clamping surface may be defined by the first fluid coupling part in which case the clamping member is connected to the second fluid flow control device.

The clamping surface may be defined by an outwardly extending projection or an inwardly extending recess. It may extend in a substantially radial direction. The clamping member may be movable into a clamping relationship with the surface in a direction substantially perpendicular to the clamping surface.

The clamping member is preferably disposed between the first and second fluid flow control devices.

The first coupling part may comprise an axially extending projection integrally formed with, or connected to, the first fluid control device. An end of the axially extending projection defines one of the interfacing surfaces. The axially extending projection may have an external surface that defines a first of the mutually co-operating guide surfaces. The external surface may be substantially cylindrical. The outwardly extending projection may extend from the external surface and may be in the form of an annular lip which may be at an end of the axially extending projection. The clamping member may comprise an axially movable member that has an opening for receipt of the axially extending projection. The opening may have a dimension (e.g. a diameter) larger than the outer dimension (e.g. a diameter) of the outwardly extending projection. A retaining ring may be disposed between the clamping surface and the clamping member such that movement of the clamping member in a first direction brings it into abutment with the retaining ring so as to apply an axial clamping force to the clamping surface so as to prevent relative rotation of the clamping member and the clamping surface and therefore relative rotation of the first and second fluid flow control devices. Preferably the retainer ring is compressible. Preferably the clamping force serves to compress seal(s) disposed between the first and second devices. The retaining ring may be a spiral retaining ring having a plurality of turns.

The retaining ring may prevent axial separation of the first and second control devices.

The clamping member may be connected to one of the first and second control devices by threaded engagement e.g. by means of at least one threaded fixing such as a bolt or screw or the like. Rotation of the at least one fixing may move the clamping member in the first direction. The fixing may pass through a bore in one of the first or second control devices.

There may be at least one second fluid path for fluid flow between the first and second fluid flow control devices. The second fluid flow path may be provided by at least one third fluid passage in the first fluid flow control device and at least one fourth fluid passage in the second fluid flow control device, the third and fourth passages meeting at openings that are disposed radially outboard of the axis of rotation.

The first and second fluid flow control devices may be fluidly coupled to the mounting member at an interface, respective interfacing surfaces of the first and second devices meeting at the interface. An annular channel may be defined in one of the interfacing surfaces, the annular channel being in communication with the respective third and fourth fluid passages of the first and second fluid flow control devices and being offset from the rotational axis.

The annular channel describes an annulus about a centre that may be substantially coincident with the axis of rotation, such that the annular channel maintains fluid communication between the third and fourth passages regardless of the relative angular position of the first and second fluid flow control devices.

There may be provided at least one seal at the interface. A first seal may be provided radially outboard of the location where the first fluid path intersects the interface. In an embodiment where there are first and second fluid paths it may be located between the rotational axis and the annular channel. A second seal may be provided radially outboard of the annular channel. The seals may be annular and received in corresponding annular recesses defined in at least one of the interfacing surfaces.

Specific embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

Figure 1 is a diagrammatic representation of a fluid circuit having a pipeline valve, a valve actuator and pneumatic control circuitry in which the rotary coupling of the present invention may be adopted;

Figure 2 is a side view of devices that form part of the control circuitry of figure

1 ;

Figure 3 is a front view of the devices of figure 2;

Figure 4 shows a directional control valve of the control circuitry supported on the valve actuator in one orientation by a rotary coupling of the present invention, shown from one side;

Figure 5 is a front view of the arrangement shown in figure 4;

Figures 6 to 9 show other orientations of the control valve relative to the valve actuator; Figure 10 is a perspective view of a mounting block to which a valve body is rotatably coupled by a rotary coupling of the present invention;

Figure 1 1 is a perspective exploded view of the arrangement of figure 10 shown from one side;

Figure 12 is a perspective exploded view of the arrangement of figure 10 shown from an opposite side to that of figure 11 ;

Figure 13 is a perspective view of the mounting block of figure 10 and 11 rotatably connected to an adapter plate for connection to a valve body;

Figures 14 to 17 are side, front, other side and rear views of the mounting block of figures 10 to 13;

Figure 18 is a sectioned view along line B-B of figure 14;

Figure 19 is a sectioned view along line A-A of figure 15;

Figure 20 is a partially sectioned view along line C-C of figure 16;

Figure 21 is a side view of the mounting block of figures 10 to 20 shown with a vent and a clamping member fitted;

Figure 22 is a sectioned view along line A-A of figure 21 ;

Figure 23 is a perspective view of the mounting block of figures 21 and 22;

Figure 24 is a perspective view from one end of a bi-directional control device of the mounting block;

Figure 25 is a longitudinal section of the device of figure 24;

Figures 26 and 27 are diagrammatic sectioned views illustrating operation of the bi-directional control device;

Figure 28 is a perspective cut-away view of the device of figures 24 to 27;

Figures 29 to 32 are part-cut away perspective views of the mounting block with the bi-directional control device, illustrating their operation;

Figure 33 is a sectioned view of a shuttle of a quick exhaust valve of the mounting block; Figure 34 is a perspective view of the valve body of figures 10 to 12;

Figures 35 and 36 are front and rear views of the valve body of figure 34;

Figure 37 is a sectioned view along line A-A of figure 36;

Figure 38 is a perspective view of pneumatic control circuit components fitted to an actuator, with a first rotary coupling between a directional control valve and a mounting block and a second rotary coupling between a directional control valve and a filter regulator, both rotary couplings in accordance with that of the present invention;

Figure 39 is a perspective view of the pneumatic control circuit components of figure 38 with one of the rotary couplings shown exploded; and

Figure 40 is a part-sectioned view of the assembled rotary coupling of figure 39.

Referring now to figure 1 of the drawings, a pipeline valve (hidden) is operable between open and closed positions by a pneumatically-operated actuator 12. In the embodiment shown the actuator 12 is a rack and pinion type in which a pair of pistons 13 are disposed in a housing 14 (typically a cylinder) for reciprocal movement. Each of the pistons 13 has an integral rack 13a designed to engage with a pinion wheel 11 mounted on a shaft 16 that is in turn connected, directly or indirectly, to an actuating stem of the valve 10. The pistons 13 serve to divide the housing 14 into separate variable volume chambers 14a, 14b and 14c. Springs 15 are disposed in the outer chambers 14a and 14b and serve to bias the piston 3 in a direction against a force applied by compressed air introduced into the central chamber 14c. It will be appreciated that the present invention has application to other actuator types in which air is selectively introduced and/or exhausted from each side of one or more pistons disposed within a housing. Moreover, it is to be understood that the present invention may have application to arrangements using other fluids besides air.

The pipeline valve may be, for example, a ball valve with a ball valve member rotationally disposed within a valve body and an actuation stem that is rotatable by the actuator pinion 11 and shaft 16 via a suitable mechanical coupling. However, it is to be understood that the present invention has application to any type of actuated valve. Moreover, whilst the actuator 12 shown in figure 1 is a spring-return embodiment the present invention has application to a double-acting arrangement where the return movement of the pistons 13 is effected by pressurisation of the outer chambers 14a, 14b whilst the central chamber 14c is exhausted.

Pressurised air for operating the actuator 12 is delivered along a main supply line 18 from an upstream source (e.g. a compressor) via a pneumatic control circuit which can take any suitable form. In the example of figure 1 fluid passes from the source towards the actuator 12 via a filter regulator 19 with pressure gauge 19a, an inline check valve 20, a pressure relief valve 21 and a normally closed, two-position, three-way solenoid-operated valve 22. Any suitable type of directional control valve may be used in place of the solenoid-operated valve. Fluid returned from the actuator 12 may be exhausted through vents 39 or 39a.

The energisation of the solenoid operator and therefore the position of the valve 22 is controlled by pneumatic pilot control signals generated by a positioner 23 in order to move the actuator 12 to a desired position to operate the valve. A position sensor 24 associated with the actuator 12 may sense the position of the pistons 13 within the housing 14, or the rotational position of the shaft 16, and generate an electrical signal representative of that position, which signal is fed back to the positioner 23. In this manner the positioner 23 may operate with closed-loop feedback control to determine the required pressure of the pneumatic control signal. The positioner 23 may be microprocessor based and may incorporate transducers that convert electrical signals (e.g. current) to pneumatic pressure for this purpose.

The present invention is concerned with a rotary coupling between components of the pneumatic control circuit on the actuator 12 or between the pneumatic control circuit and the actuator 12. In figure 1 , a mounting block represented schematically by the dotted line 27 is shown between the solenoid operated control valve 22 and the actuator 12. The actuator 12 has a Namur standard interface comprising ports for fluid communication with the chambers 14a, 14b and 14c and threaded fixing bores. Such an interface is well known to those skilled in the art. The mounting block optionally houses a bi-directional flow control device 120 and a quick exhaust valve 91 both of which are described in detail later.

A physical embodiment of part of the pneumatic control circuit of figure 1 is shown in figures 2 and 3, including the solenoid-operated valve 22, the filter regulator 19, pressure gauge 19a, pressure relief valve 21 and check valve 20 all arranged in a stack. The solenoid-operated valve 22 has a valve body 25 (mostly hidden in figure 2) which forms part of a mounting arrangement for connection to a Namur standard interface of the valve actuator 12 (not shown in figures 2 and 3). The mounting arrangement includes the mounting block 27 for connection to the Namur interface and which permits rotation of the valve body 25, and a clamping member 28 interposed between the valve body 25 and the mounting block 27 for selectively locking the valve body against rotation. The mounting block 27 is generally parallelepiped with various ports for connection into the pneumatic control circuit and various bores and tapped bores for receipt of fixings. The ends 30 of threaded shanks of two socket head screws 31 can be seen projecting from mounting bores 32 (not shown in figure 2, but present in figures 10, 12 and 14) in the mounting block 27 in figure 2 and these are designed to connect to corresponding threaded fixing bores defined in the Namur interface on the actuator 12, the screws 31 passing through bores in the block 27.

The above arrangement is shown connected to the external Namur interface surface 33 of the valve actuator 12 in figures 4 and 5 with the solenoid-operated valve 22 disposed in a conventional orientation where its longitudinal axis extends substantially perpendicular to the longitudinal axis of the actuator 12. The filter regulator 19, pressure gauge 19a, in-line check valve 20 and pressure relief valve 21 have been omitted for clarity. The ball valve 10 (not shown in figures 4 and 5) is typically connected underneath the actuator 12 with the valve positioner 23 (not shown in figures 4 and 5) typically mounted on top.

Figures 6 to 9 show alternative orientations of the valve body 25 relative to the actuator 12 which can be achieved by releasing the clamping member 28 and rotating the valve body 25 around the mounting block. The clamping member 28 is released by turning locking screws 34 (see figures 5 and 9) to release the clamping force as will be described in more detail below. This allows the valve body 25 to be rotated to any desired position. The positions depicted in figures 6 and 7 are temporary and simply allow the valve 25 to be oriented in such a way that access bores 35, 36 through the valve body 25 and the clamping member 28 are brought into alignment with the heads of the socket head screws 31 that fix the mounting block 27 to the valve actuator 12. This allows the mounting block 27 to be fixed to the interface 33 of the valve actuator 12 with the valve body 25 and other devices already assembled and connected.

In figure 8 the valve body 25 is oriented with its longitudinal axis substantially parallel to that of the actuator 12 and is fixed in that position by tightening the locking screws 34 to effect clamping, the locking screws being received in bores 37 that pass through the valve body 25. This orientation ensures it avoids physical interference with devices mounted to the top of the actuator 12 (such as the positioner 23 which is not shown in figures 4 to 9) and ensures that flame path clearances are maintained. An alternative orientation is shown in figure 9 where the actuator 12 is inclined and the valve body 25 is oriented to ensure the filter regulator 19 (shown in this figure) has an upright attitude. This is desirable as the filter regulator 19 is fitted with a drain which collects moisture delivered to it under gravitation force and which should be drained at regular intervals. In order for the moisture to be drained effectively from the device it should be maintained in the upright attitude. The valve body 25 can again be locked in this position by tightening the locking screws 34 to effect clamping. In an alternative arrangement a rotatable coupling may be provided between the filter regulator 19 and the valve body 25 to allow the filter regulator 19 to be maintained in an upright attitude regardless of the orientation of the other components. Such an embodiment is described later in relation to figures 38 to 40.

It will be appreciated that the mounting arrangement may be designed so that valve body 25 can be selectively clamped in one of an infinite number of positions or there may be a finite number of discrete positions.

Referring now to figures 10-20, the mounting block 27 comprises a body that defines an external front face 40 with a pair of ports 41 , 42 for fluid connection to corresponding ports defined on the Namur interface surface 33 of the valve actuator 12, an opposite rear face 43 for fluid connection to the valve body 25, opposed side faces 44, 45 and upper and lower faces 48, 49. One of the side faces 44 has a large side port 46 for connection to optional ancillary devices or a vent 39 (one of which is shown in figures 10 to 13) and a smaller side port 47 for exhaust flow. The ports 41 , 42 on the front face 40 are shallow and lined by O-ring seals 50 for sealing against Namur interface surface 33. A first of the ports 41 provides fluid communication between the valve body 25 and the central cylinder chamber 14c and a second of the ports 42 provides fluid communication between the valve body 25 and the outer cylinder chambers 14a, 14b which are occupied by the springs 15.

The side port 46 penetrates into the body of the mounting block 27 where it defines a chamber 51 for fluid communication with the first and second ports 41 , 42 on the front face 40.

The mounting block 27 has an integrally formed cylindrical boss 56 that projects from the rear face 43 and is designed to support the clamping member 28 as will be described below. The boss 56 is penetrated by a central flow passage 57 that provides communication between the chamber 51 and a feed port of the valve body 25 and two radially outer fluid passages 58 that provide fluid communication between the second port 42 and an exhaust port of the valve body 25. A plurality of annular recesses are defined in the end face of the boss 56: radially inner and outer recesses 59, 60 for CD- ring seals 61 , 62 and an intermediate recess forming an annular channel 63 for fluid flow into which the outer passages 58 emerge. The radially inner recess 59 surrounds the central flow passage 57 and receives a first O-ring seal 61 for sealing against the valve body 25 to ensure that fluid does not leak from the central flow passage 57 into the annular channel 63 or vice versa. Similarly, fluid is prevented from leaking from the annular channel 63 to the surrounding environment by the radially outer O-ring seal 62 that is located immediately outboard of the annular channel 63.

The mounting block 27 is shown clamped to the rotatable valve body 25 in figures 10-12. In this instance the valve body 25 is compatible with the mounting block 27 in that the feed and exhaust ports in the valve body are in fluid communication with the central flow passage 57 and the outer fluid passages 58 in the mounting block 27. In an alternative embodiment, shown in figure 13, the mounting block 27 is connected to a valve body 25 via an intermediate adapter plate 100 that effectively renders the mounting block 27 compatible with alternative valve body designs. It will be appreciated that adapter plates 100 of various designs can be supplied with the mounting block 27 to render it compatible with different valve bodies 25 or the adapter plate can be manufactured in a bespoke fashion to provide a suitable interface with the valve body 25 and the mounting block 27. In order that the valve body 25 is selectively rotatable relative to the mounting block as before, the adapter plate 100 is designed to rotate on the boss 56 and be clamped by clamping member 28 in the same manner as described in relation to the valve body 25.

The adapter plate has a feed bore 101 and an exhaust bore 102 for directing air supply and return between the actuator and the valve body and is penetrated by bores 103 for receipt of the locking screws 34 and bores 104 for access to the socket head fixing screws 31 of the mounting block 27. In order to control the speed of flow of air to and from the central chamber 14c the mounting block 27 is provided with a bi-directional flow control device 120, which is depicted in figures 10-13 and 21-32 but is shown most clearly in figures 24 and 25. It is in the form of a cartridge and comprises a generally cylindrical hollow body 121 that is disposed in the mounting block 27 adjacent to the first and second ports 41 , 42 and such that its longitudinal central axis extends in a direction that is generally perpendicular to the flow into and out of those ports 41 , 42. The body 121 resides in a cylindrical bore 122 of the mounting block 27 that extends between the two side faces 44, 45 and has a length that is greater than that of the bore 122 such that its ends project beyond the side faces 44, 45. The cylindrical bore 122 is in communication with the first and second ports 41 , 42 via respective short bores 123, 124, with the two outer fluid passages 58, and with the side port 46 via two perpendicular passages 125,126, a first 125 of which extends from an opening in the bore 122 and extends to the smaller side port 47 and a second 126 of which extends from the smaller side port 47 to the larger side port 46. However, as will become apparent only air to and from the port 41 flows through the interior of the body 121.

The bi-directional control device 120 has an external surface with four annular grooves 130, 131 , 132, 133 that receive O-ring seals 134. In the space between pairs of adjacent seals 134 the external surface has a reduced diameter such that when the body 121 is received in the cylindrical bore 122 there are three annular clearances that serve as external flow paths 135, 136, 137 for fluid to flow around the surface of the body 121. The body 121 is penetrated by two arrays of radial apertures 138 each arranged around the circumference to provide fluid communication between an outer two of the flow paths 135, 137 and the hollow interior of the body 121. Each end of the interior of the body is closed by a flow screw 140, 141 that has a head 142, whose outer periphery is threaded for engagement with a corresponding thread 143 defined in the internal surface of the body 121 , and a shank 144 which is hollow at an end distal from the head 1 2. Access to an end surface of each head 142 is provided through the otherwise open end of the body 121 , the head having a slot 145 for engagement with a screwdriver or similar tool such that the screw can be rotated to adjust its axial position. The hollow end of each shank 144 is provided by a central blind bore 146 that extends substantially in parallel to the bore 122 in the body 121. The blind bore 146 is defined by an internal surface of the shank 144 which is generally circular in cross-section and tapers outwardly at its open end distal the head 142 to define a substantially frustoconical seat 147. The hollow part of the shank 144 is penetrated by an array of equi-angularly spaced radial apertures 148 that provide fluid communication between an external surface of the shank 144 and the blind bore 146 at a location spaced from the seat 147.

The internal surface of the body 121 is substantially cylindrical but is stepped to define different diameters. As described above, the body 121 is penetrated by two arrays of radial apertures 138 which extend from the external annular flow paths 135, 137 and emerge on the interior side of the body 121 into internal annular flow paths 150, 151 that are defined by annular recesses formed in the interior surface of the body 121. The internal annular flow paths 150, 151 are in fluid communication with the radial apertures 149 in the respective flow screws 140, 142 and are sealed from the rest of the interior of the body by a pair of axialiy spaced O-ring seals 152 received in annular grooves defined on either side. Each path 150, 151 thus provides a radial clearance between the body 121 and the respective flow screw 140, 141.

In the central area of the interior of the body 122 there is a floating shuttle member 155 that is axialiy moveable under the influence of fluid pressure between the frustoconical seats 147 defined on the open ends of the flow screws 140, 141. The shuttle member 155 is shown in section or cut-away in figures 24, 26-27, and 29-32 but its external profile can be most clearly seen from figure 28. It comprises a central section 156 which is substantially square in cross-section and outer end portions that are cylindrical immediately adjacent to the central section 156 and then taper inwardly to provide a frustoconical profile. These frustoconical end portions 157 serve as valve elements that interact with the frustoconical seats 147 much in the same manner as a needle valve operates. The axial travel of the shuttle member 155 is limited in each direction by a circlip 158, 159 that is received in an annular groove in the inside surface of the body 121. A first circlip 158 is disposed between the first flow screw 140 and the central section 156 of the shuttle member 155 and a second circlip 159 is disposed between the second flow screw 141 and the central section 156. The inner edge of each circlip 158, 159 has a diameter that is greater than the largest diameter of the frustoconical end portions 157 but smaller than the radial dimensions of the central section 156 such that the ends 157 may pass through the respective circlip 158, 159 but the central section 156 is prevented from doing so. At end faces of the central section 156 there are four axially projecting stop members 160, one at each corner, for abutment with the circlip 158, 159. These ensure that when the shuttle member 155 reaches the end limit of its travel fluid can still flow between it and the circlip on the basis that sealing contact is made with the circlip 158, 159 only at the four spaced stop members 160 leaving axial clearances between the end face of the central section 156 and the circlip 158, 159 in the region between the stop members 160.

The central section 156 of the shuttle member 155 is penetrated by a through bore 161 that extends between upper and lower faces 156a, 156b of the central section in a direction perpendicular to the axis of the body 121. A further bore 162 extends from the centre of one end portion 157 and intersects with the through bore 161 at a right angle. The further bore 162 has a small diameter portion 162a for limiting the flow therethrough.

The axial position of the flow screws 140, 141 and the relative position of the shuttle member 155 determine the fluid flow rate through the device, the position of the flow screws being adjustable by virtue of the threaded engagement of the head 142 and the inside surface of the cylindrical body 121. The travel of the flow screw 140, 141 into the body 121 is limited by abutment with a respective circlip 158, 159 and the end of the screw shank 144 has an annular recess in its outer surface for receipt of the circlip 158, 159. This movement is accommodated by the axial length of each of the internal annular flow paths 150, 151 such that there is no the loss of fluid communication between the flow screws 140, 141 and the external annular flow paths 135, 137.

In operation, the bi-directional flow control device 120 allows flow in either direction along the inside of the body 121 and provides independent regulation of the flow rate of fluid flowing between the external annular flow paths 135 and 137.

Figure 26 illustrates operation when the fluid flows flow left to right, entering the body 121 from the external annular flow path 135 via radial apertures 138 as indicated by the arrows. When the device 120 is used in the mounting block 27 this fluid is air that flows from the valve body feed port and is introduced into the mounting block 27 via the central flow passage 57 for supply to the central chamber 14c of the actuator 12. The fluid enters the internal annular flow path 150, flows into the flow screw 140 via the radial apertures 148 and then encounters the shuttle member 155. On the other side of the shuttle member 155 the flow screw 141 is in fluid communication with the central chamber 14c of the actuator via first port 41 , external annular flow path 137, radial apertures 138 in the body 121 and internal annular flow path 151. Since the pressure of the air from the valve body feed is greater than that in the central chamber 14c the shuttle member 55 is forced to the right against the stop provided by circlip 159. Air flows out of the first flow screw 1 0 around the shuttle member 155, between the stop members 160 and the circlip 159 and into the open end of the second flow screw 141. From there the air egresses through the radial apertures 148 to the internal annular flow path 151 , out through the radial apertures 138 in the body 121 to the external annular flow path 137 and first port 41. The flow rate of the air is determined by the axial clearance between the frustoconical surface of the right hand end 157 of the shuttle member 155 and the corresponding frustoconical seat 147 of the second flow screw 141. This flow rate can be altered in advance or otherwise using a screwdriver or other suitable tool to adjust of the axial position of the second flow screw 141 so as to vary the clearance that exists between the frustoconical surface 157 and the seat 147 when the shuttle member 155 is at the right-hand extremity of its travel length.

Figure 27 illustrates flow in the opposite direction from right to left. In this instance fluid flows from the external annular flow path 137 into the body 121 via radial apertures 138 to the internal annular flow path 151 and then into the second flow screw 141 via the radial apertures 148, as indicated by the arrows. In the context of the mounting block 27 this is the direction of air flow when the valve 22 is de-energised and the air supply to the actuator 12 is shut off. In this circumstance the supply of air to the central chamber 14c of the actuator 12 is interrupted and the force applied by the springs 15 is now greater than that applied by the pressure in the central chamber 14c such that the pistons 13 move towards each other and air is expelled from the central chamber 14c to the first port 41 in the mounting block 27. On the other side of the shuttle member 155 the external annular flow path 135 is in communication with the feed port of the valve body 25 and is therefore at a lower pressure than that flowing from the second feed screw 141 to the shuttle member 155. As a result the shuttle member 155 is forced to move from right to left and into abutment with the circlip 158. The air from the second flow screw 141 flows around the shuttle member 155 and passes through the clearances between the stop members 160 and the circlip 158 into the first flow screw 140 and out through the radial apertures 148, the internal annular flow path 150, the radial apertures 138 to the external annular flow path 135. The rate of flow is controlled by the axial position of the first flow screw 140 and in particular by the clearance between the frustoconical seat 147 defined on the screw 140 and the frustoconical surface 157 defined on the end of the shuttle member 155. The flow in this direction allows the central chamber 14c of the actuator to be exhausted.

In both flow directions the respective flow screw 140, 141 that is used to control the flow rate can be adjusted to a position where the frustoconical surface 157 seals against the seat 147 thus preventing flow between them regardless of the pressure difference. In the case where pressure at the external annular flow passage 137 on the right is greater than that at the passage 135 on the left a small flow is permitted by virtue of the bores 161 , 162 in the shuttle 155 which allow a small bypass flow into the first flow screw 140, the flow rate being determined by the size of the small diameter bore 162a.

The mounting block 27 incorporates a quick exhaust valve that allows rapid exhaust of the central chamber 14c. The quick exhaust valve 91 (shown in figures 11 , 12, 29 and 31) is housed in the chamber 51 of the mounting block 27 and comprises a shuttle 92 that is moveable axially in the chamber 51 towards and away from a shuttle seat 93 located adjacent to the larger side port 46. The shuttle 92 is disposed between the shuttle seat 93 and the central flow passage 57 and is in the form of a solid disc of elastomeric material with a peripheral skirt 94 that flares outwardly (see figures 11 , 12 and 33). The shuttle seat 93 is generally in the form of a hollow cylinder with a first end that defines an annular seating surface 95 against which the shuttle 92 comes into sealing contact and a second end 96 that is penetrated in the radial direction by a plurality of apertures 97. At a location between the first and second ends, the outer surface of the seat 93 receives an annular seal 98 that seals against the wall of the chamber 51 to prevent air flow around the outside of the seat between the first and second ends. Between the annular seal 98 and the shuttle 92 there is a bore 53 in the mounting block 27 that provides fluid communication between the chamber 51 and the external annular flow path 135 around the body 121 of the flow control device 120. On the other side of the seal 98 there is a further bore 54 that provides fluid communication between the chamber 51 and the short bore 124 that is connected to the port 42.

Figures 29-32 illustrate the operation of the bi-directional flow control device 120 in the mounting block 27. The components are partly cut-away so as to reveal the air flow paths.

Figure 29 illustrates air being supplied to the central chamber 14c of the actuator 12. Air is delivered via the energised valve 22 to the central flow passage 57 in the boss 56 on the rear face 43 of the mounting block 27. From there it passes into the chamber 51 and pressure acts on the right hand face of the shuttle 92 (as shown in figure 29) so as to move it on to the annular seating surface 95 of the shuttle seat 93. In this position air cannot flow along the inside of the shuttle seat 93 and to the side port vent 46 but is incident on the annular skirt 94 which deflects radially inwards as a consequence. The air thus cannot enter the quick exhaust valve 91 and is forced to flow instead through the bore 53 into the external annular flow path 135 from where it enters the bi-directional flow control device 120 as described above in relation to figure 26. The quick exhaust valve 91 is thus closed in the manner of a check valve.

As described above the fluid in the flow control device 120 is directed to the central chamber 14c of the actuator 12 through the first port 41 in the mounting block 27 and the corresponding feed port for central chamber 14c defined on the Namur interface surface 33 of the valve actuator 12. At the same time as air is introduced into the central chamber 14c it is also expelled from the outer chambers 14a and 14b via a port on the Namur interface 33 since the supply of air pressure to the chamber 14c forces the pistons 13 to move against the biasing force of the springs 15. As illustrated in figure 30, the air is exhausted from the spring side (by virtue of the reduction of volume of the chamber on that side) and flows through the port in the Namur interface to the second port 42 in the mounting block 27, through short bore 124 and into a first of the perpendicular passages 125. From there the air can flow to the left where it encounters the central external annular flow passage 136 of the fluid control device 120 and flows out through one or both of the outer fluid passages 58 so that it can be vented through the valve body 25. In addition, or alternatively, if the side port 46 is not blocked it may flow to the right where it passes into the second of the perpendicular passages 126 to the side port 46 and vent 39 from where it is exhausted. There may also, or alternatively, be provided a vent port in the front face of the mounting block, particularly if the side port 46 is blocked by a blanking plate. It will be understood by the skilled person that vents may be selectively blocked by appropriate bungs, plugs or blanking plates as required.

Figure 31 illustrates the flow of air in the instance where the valve is de- energised so that air supply pressure to the central chamber 14c of the actuator 12 from the main supply line 18 is interrupted by the valve 22 and there is no supply of compressed air to the actuator 12. In this instance the springs 15 force the pistons 13 inwardly so that air is evacuated from the central chamber 14c through the port in the Namur interface surface 33 to the port 41and into the bi-directional control device 120. The flow through the device 120 follows that described in relation to figure 27 such that it emerges at the external annular flow path 135, as indicated by the arrows. From there it enters the chamber 51 through bore 53 and forces the shuttle 92 away from the shuttle seat 93 thus opening the quick exhaust valve 91. The air pressure acts on the underside of the skirt 94 of the shuttle 92 such that it is forced radially outwards to seal against the wall of the chamber 51. This prevents the air from passing into the central fluid passage 57 and forces it to pass along the interior of the shuttle seat 93 (the outer periphery being sealed by annular seal 98 against the wall of the chamber 51 ). If the side port 46 is closed by the blanking plate such that there is no vent 39 the air is forced radially outwards through the apertures 97 and circulates around the second end of the shuttle seat 93 before it egresses through bore 54 to the short bore 124 and the port 42, as shown in figure 32. In this manner the air is routed to the port on the Namur interface surface 33 that is connected to the outer chambers 14a, 1 b occupied by the springs 15. This arrangement allows air flowing out of the central chamber 14c to be recirculated to the other chambers 14a and 14b to assist the spring forces in reducing the volume of the central chamber 14c.

In an alternative embodiment where the quick exhaust valve is not required or if the actuator pistons 13 are non-spring return types, then the quick exhaust valve shuttle 92 and seat 93 are replaced in the chamber 51 by a bung (not shown). In this instance air from the valve 22 is delivered to the chambers 14a, 14b to force the central chamber 1 c to exhaust.

The valve body 25 is shown in more detail figures 10 to 12 and 34 to 37. It is generally parallelepiped with a front face 65, a rear face 66, side faces 67, 68, upper face 69 and lower face 70. A first bore extends between the upper and lower faces 69, 70 and defines a valve chamber 71 for receipt of the valve element 72 which is operated by the solenoid (shown in figures 2 to 9). The valve element 72 can take any suitable form but in the particular embodiment shown is a spring-biased normally closed poppet-type valve element for axial reciprocation between upper or lower seat 73a, 73b. The solenoid is received in threaded engagement with the wall of an enlarged opening 74 in the upper face 69 and has a plunger (not shown) for connection to the valve element 72 for controlling reciprocation of the valve element 72. The internal operation of the valve is not important for understanding the present invention and therefore will be described only in general terms in order to provide an understanding of the directions of flow of air to and from the mounting block 27. One of the side faces 67 has a pair of air supply bores 75 for fluid communication with the main supply line 18 and these provide fluid communication with an upper part of the valve chamber 71 above the upper valve seat 73a. The rear face 66 of the valve body is penetrated by an exhaust bore 76 for directing exhaust fluid to a suitable vent. The exhaust outlet bore 76 is in fluid communication with a lower part of the valve chamber 71 below the lower seat 73b. Exhaust fluid is supplied from the actuator 12 to the valve body via two small exhaust inlet bores 76a that provide fluid communication between the outer fluid passages 58 of the mounting block 27 and the lower part of the valve chamber 71.

The front face 65 of the valve body 25 is penetrated by a feed port 77 for supplying air to the actuator 12 and which is in fluid communication with a central part of the valve chamber 71 generally between the valve seats 73a, 73b. When connected to the mounting block 27 the feed port 77 is in fluid communication with the central flow passage 57 in the boss 56 of the mounting block 27.

The valve body 25 is also penetrated by a first pair of bores 37 that extend between the front and rear faces 65, 66 and are designed to receive the locking screws 34, and a second pair of bores 35 that provide access for the mounting screws 31 of the mounting block 27.

The valve will be normally closed (i.e. when the solenoid is de-energised) such that the upper part of the valve chamber 71 is sealed from communication with the central or lower parts by means of the valve element 72 being sealed to the upper valve seat 73a. In this position the air supply bores 75 (and therefore the main supply line 18) are blocked from communication with feed port 77 so that pressurised air is not supplied to the actuator 12.

The exhaust bores 76a receiving exhaust fluid from the actuator 12 are permanently in communication with the exhaust bore 76 so as to allow exhaust fluid to pass to vent.

When the solenoid is energised the valve element 72 is moved off the upper seat 73a and into sealing engagement with the lower seat 73b. This has the effect of bringing the air supply bores 75 into fluid communication with the actuator feed port 77 whilst blocking the from communication with the exhaust flow path through bores 76 and 76a so that pressurised fluid is supplied to the actuator 12. The valve body 25 is rotatable about an axis that is substantially coaxial with a central longitudinal axis of the central flow passage 57 so that alignment of the latter with the feed port 77 is maintained. As the body 25 rotates about this axis, the exhaust bores 76a describe a circle that is aligned with the annular channel 63. The configuration of seals and recesses thus allows exhaust air from the actuator 12 that egresses through the outer flow passages 58 in the mounting block 27 to flow into and around the annular channel 63 and out through the exhaust bores 76a in the valve body 25, regardless of the rotational orientation of the valve body 25. In this particular embodiment there is a pair of exhaust bores 76a and a pair of outer fluid passages 58 to ensure adequate volumetric flow rate without having to increase the size of the valve body 25 and mounting block 27. It is to be appreciated that in an alternative embodiment there may be a larger single exhaust bore 76a and larger single outer fluid passage 58.

Referring now to figures 10 to 13, 18 to 20 and 22 to 23 in particular, the external peripheral surface of the boss 56 on the mounting block 27 is recessed at 78 for receipt of the clamping member 28 which, in use, clamps the end face of the boss 56 to the valve body 25 such that the O-ring seals 61 , 62 are compressed and provide effective sealing. This recess 78 leaves an annular lip 79 defined at the end of the boss 56 through which the clamping force is transmitted in use.

The clamping member 28 is approximately square in outer profile with a front face 80, a rear face 81 and a circular opening 82 that has a diameter slightly larger than the outer diameter of the lip 79 so that the boss 56 can pass through the opening 82. The rear face 81 (which faces the valve body 25) has a circular recess 83 such that a rear-facing shoulder 84 is defined by the clamping member 28. A spiral retaining ring 85 is disposed between the shoulder 84 and the lip 79 on the boss 56 and has an inner diameter that is less than the outer diameter of the lip 79 so as to retain the clamping member 28 on the boss 56 and thus prevent axial separation of the mounting block 27 and the valve body 25. A ring of this kind typically comprises two or more turns of an elongate thin strip of material having a rectangular cross-section. When the locking screws 34 are tightened they serve to draw the clamping member 28 over the boss 56 towards the valve body 25 but it is prevented from moving past the lip 79 by the spiral retaining ring 85 which is compressed between shoulder 84 and the lip 79. The clamping force is transmitted from the shoulder 84 of the clamping member 28 through the spiral retaining ring 85 to the lip 79 of the boss 56 so that the boss is pulled on to the front face 65 of the valve body 25 and sealing is effected via the compressed O- ring seals 61 , 62. In so doing the valve body 25 and clamping member 28 are locked against rotation relative to the mounting block 27 and therefore relative to the valve actuator 12.

The clamping member 28 has a first pair of bores 36 that afford access to the mounting screws 31 , when the clamping member is rotated to an orientation where the bores 36 are aligned to the screws 31. It also has a second pair of tapped bores 36a which are designed to engage with the locking screws 34.

In order to rotate the valve body 25 relative to the actuator 12 the locking screws 34 are loosened so that the clamping member 28 is released from clamping engagement with the lip 79 but the screws 34 remain engaged in the tapped bores 36a so as to maintain the clamping member 28 and valve body 25 in a fixed rotational relationship. This allows the clamping member 28 to rotate about the external peripheral surface of the boss 56 as the valve body 25 is rotated. The screws 34 are then tightened in the new position to clamp the valve body 25 in position once again. Since the rotation occurs about the longitudinal axis defined by the central flow passage 57 in the mounting block 27 and the feed port 77 in the valve body 25, the exhaust bores 76a orbit the axis in a circle and regardless of the new orientation of the valve body 25 they remain in flow communication with annular channel 63. In this manner flow communication between the actuator 12 and the valve body 25 is not interrupted by rotation of the valve body 25.

In operation, when the valve 22 is de-energised the spring force on the pistons 13 may be greater than that applied by the prevailing pressure in the central chamber 14c in which case the pistons 13 move and air is evacuated from the chamber 14c through the port in the Namur interface 33, the first port 41, through the bi-directional flow control device 120 and then redirected to the outer chambers 14a, 14c as described above. In an alternative arrangement the air may be directed to the exhaust flow path through the valve body 25 to vent 39a or to an alternative vent, such as 39, provided in the mounting block.

When the solenoid is energised to open the valve 22 air is supplied from the main supply line 18 to the central chamber 14c via the supply bores 75 and the feed port 77 in the valve body 25, the central flow passage 57 in the mounting block 27, the flow control device 120 to the first port 41 and the corresponding port in the Namur interface 33 of the actuator 12. The pressurisation of the central chamber 14c acts against the spring force and the outer chambers 14a, 14b decreases in volume. As this happens air from the outer chambers 14a, 14b is allowed to vent through the second port 42, and the flow control device 120 to the outer flow passages 58 of the mounting block 27 to the inlet exhaust bores 76a and outlet exhaust bore 76 in the valve body 25. As described above the exhaust air may alternatively be directed in part or in whole to the vent 39 in the mounting block 27.

It will be appreciated that the precise configuration of the air supply and exhaust paths may be varied whilst not departing from the scope of the present invention. For example, pressurised air may be supplied to the annular channel 63 and the outer flow passages 58 in an alternative valve body and/or mounting block configuration.

The valve mounting arrangements described are configured such that the mounting block 27 can be mounted on, and fastened to, the Namur interface 33 of the actuator 12 with the devices of the pneumatic control circuit present. The access bores 35, 36 through the valve body 25 and clamping member 28 permit the captive mounting screws 31 to be fastened into threaded fixing bores on the Namur interface 33. This enables the supplier to provide a complete assembled kit for installation on the actuator as opposed to providing multiple separate devices, ancillary components and accessories, or sub-assemblies of such devices, components and accessories, which the end user has to install.

The rotational coupling between the mounting block 27 and the valve body 25 may be adopted in other parts of the pneumatic control circuit so that components may be orientated in the most convenient manner for assembly or installation or in the most effective manner for operation. For example, in the embodiment of figures 38 to 40 the filter regulator 19 is coupled to the valve body 25 by a rotary coupling 180. It will be appreciated that such coupling can be provided between any two components of a pneumatic control circuit such as that shown in figure 1 or otherwise, irrespective of whether there is a rotational coupling between the mounting block and the circuit.

Air is delivered from the filter regulator 19 to the valve 22 along the main supply path 18 as illustrated in figure 1. The filter regulator 19 has an outlet 181 that supplies air to a pair of inlets 182 of the valve body 25, both the outlet 181 and inlets 182 being in the supply path 18. It will be understood that only one inlet 182 may be provided in alternative embodiments. The rotary coupling comprises a first cylindrical part that defines a boss 183 with a radially outwards extending flange 184 by which it is connected to the body of the filter regulator 19 with screws 185. The boss 183 is penetrated by a central passage 186 for conveying fluid from the filter regulator outlet 181 to the valve inlet 182. Seals 187 at the interface between the boss 183 and the other two components prevent fluid leaking from the central passage 186. The end of the boss 183 which is proximate the valve body 25 has an annular groove 188 which is designed to receive a retaining ring 195. The clamping ring 189 is very similar to that described in the embodiments above except that is has a circular outer surface 190 as well as a circular inner surface 191. As in the previous embodiment the clamping ring 189 is recessed to define a substantially radially extending annular shoulder 192 for cooperation with the retaining ring 195. The inner surface 191 has a diameter which is slightly larger than the outer diameter of the boss 183 so as to permit the clamping ring 189 to pass over the boss 183 but a spiral retaining ring 195 (of the same kind described above) interposed between the annular groove 188 and the annular shoulder 192 has an outer diameter greater than that inner surface 191 so as to retain the clamping member 189 on the boss 183.

When the two components are connected the clamping ring inner surface 191 of the clamping ring 189 is supported on the outer surface of the boss 183 and they cooperate to guide relative rotation between the two parts.

As before the clamping ring 189 is connected to the valve body by means of socket screws 196 that pass through bores 197 in the valve body 25 and into threaded bores 198 in the clamping ring 189. The turning of the screws 196 results in axial movement of the clamping ring 189 relative to the valve body 25. In order to clamp the valve body 25 and filter regulator 19 against relative rotation the screws 196 are rotated so as to draw the clamping member axially along the boss 183 to a point where it engages the retaining ring 195. Further rotation of the screws 196 in the same direction compresses the retaining ring 195 against a radially extending face of the recess 188 such that a clamping force is applied to that face. This prevents relative rotation of the clamping member 189 and the boss 183 and therefore relative rotation of the valve body 25 and the filter regulator 19. Rotation of the screws 196 in the opposite direction releases the clamping force and allows the clamping member 189 to travel in the opposite axial direction. This allows the filter regulator 19 to be rotated relative to the valve body 25 to a desirable position before it is clamped in place. It will be understood that the rotary coupling 180 allow clamping in an infinite number of positions. In other embodiments the coupling 180 may be designed to permit clamping in a finite number of discrete positions. The relative rotation occurs about an axis that is substantially coincident with the central passage 186 and therefore with the inlets 182 and outlet 181 so that the main supply fluid path 18 is not interrupted regardless of the rotation orientation of the components.

It is will be appreciated by one of ordinary skill in the art that the invention has been described by way of example only, and that the invention itself is defined by the claims. Numerous modifications and variations may be made to the exemplary design described above without departing from the scope of the invention as defined in the claims. For example, the precise shape and configuration of the various components may be varied. Moreover, the boss 56, 183 may be defined on, or connected to, the valve body 25 with the clamping member 28 being designed to move away from the valve body to effect clamping. In a further alternative the annular channel 63 may be defined in the valve body 25 for communication with the exhaust bores 76a and outer passages 58.

The described and illustrated embodiments are to be considered as illustrative and not restrictive in character, it being understood that only the preferred embodiments have been shown and described and that all changes and modifications that come within the scope of the inventions as defined in the claims are desired to be protected. It should be understood that while the use of words such as "preferable", "preferably", "preferred" or "more preferred" in the description suggest that a feature so described may be desirable, it may nevertheless not be necessary and embodiments lacking such a feature may be considered as within the scope of the invention as defined in the appended claims. In relation to the claims, it is intended that when words such as "a," "an," "at least one," or "at least one portion" are used to preface a feature there is no intention to limit the claim to only one such feature unless specifically stated to the contrary in the claim. When the language "at least a portion" and/or "a portion" is used the item can include a portion and/or the entire item unless specifically stated to the contrary.

Claims

An assembly comprising a first fluid flow control device coupled to a second fluid flow control device, the first fluid flow control device having a body with a first fluid passage and the second fluid flow control device having a body with a second fluid passage, the first and second fluid passages being in fluid communication to form a first fluid path, the first and second fluid flow control devices being coupled together by means of a rotary coupling comprising a first coupling part and a second coupling part defining mutually co-operating guide surfaces for supporting relative rotation of the first and second fluid flow control devices, the first coupling part provided by the first fluid control device and being penetrated by at least part of the first fluid passage, the second coupling part connected to one of the first and second fluid flow control devices and comprising a releasable clamping member for movement between a first position in which the first and second fluid flow control devices are rotatable relative to one another about a rotational axis and a second position in which it applies a clamping force to a clamping surface of the other of the first and second fluid flow control devices so as to clamp the devices against relative rotation in at least one selected position.

An assembly according to claim 1 , wherein the rotational axis is substantially coincident with the centre of the part of the first fluid passage that penetrates the first fluid coupling part. An assembly according to claim 1 or 2, wherein the first coupling part comprises an axially extending projection integrally formed with or connected to the first fluid control device. An assembly according to claim 3, wherein the axially extending projection has an external surface that defines a first of the mutually co-operating guide surfaces. An assembly according to claim 4, wherein the external surface is substantially cylindrical. An assembly according to claim 1 or 2, wherein the clamping surface is defined by a substantially radially extending surface. An assembly according to any one of claims 3 to 6, wherein the clamping surface is defined by a substantially radially extending surface on the axially extending projection. An assembly according to claim 6 or 7, wherein the radially extending surface is defined by a projection from or a recess in the axially extending projection. An assembly according to any preceding claim, wherein the clamping member is moveable into clamping relationship with the clamping surface in a direction substantially perpendicular to the clamping surface. An assembly according to any one of claims 3 to 5, wherein the clamping member comprises an axially movable member that has an opening for receipt of the axially extending projection. An assembly according to claim 10, wherein the opening has a dimension larger than the outer dimension of the outwardly extending projection. An assembly according to any preceding claim wherein there is provided a retaining ring between the clamping surface and the clamping member such that movement of the clamping member in a first direction brings it into abutment with the retainer ring so as to apply an axial clamping force to the clamping surface to prevent relative rotation of the clamping member and the clamping surface and therefore relative rotation of the first and second fluid flow control devices. An assembly according to clam 12, wherein the retaining ring is compressible. An assembly according to claim 12 or 13 wherein the retaining ring prevents axial separation of the first and second fluid flow control devices. An assembly according to any preceding claim, wherein the clamping member is connected to one of the first and second control devices by threaded engagement.

An assembly according to claim 15, further comprising at least one second fluid path for fluid flow between the first and second fluid flow control devices, the second fluid flow path being provided by at least one third fluid passage in the first fluid flow control device and at least one fourth fluid passage in the second fluid flow control device, the third and fourth passages meeting at openings that are disposed radially outboard of the axis of rotation. An assembly according to claim 16, wherein the first and second fluid flow control devices are fluidly coupled together at an interface, respective interfacing surfaces of the first and second devices meeting at the interface. An assembly according to claim 17, wherein an annular channel is defined in one of the interfacing surfaces, the annular channel being in communication with the respective third and fourth fluid passages of the first and second fluid flow control devices and being offset from the rotational axis. An assembly according to claim 18, wherein the annular channel describes an annulus about a centre that may be substantially coincident with the axis of rotation, such that the annular channel maintains fluid communication between the third and fourth passages regardless of the relative angular position of the first and second fluid flow control devices.