Fluid flow control valves

A duck bill valve used to control fluid flow is contained in a sleeve whose wall is apertured to permit the application to the flaps of the valve of radial pressure to open the valve and permit fluid flow. A button located on the sleeve is provided to enable a user to apply the radial pressure when the valve is to be opened.

FIELD OF THE INVENTION 
This invention relates to fluid flow control valves and has particular but 
not exclusive reference to the flow control of gases and liquids in which 
back pressure develops when the flow control valve is closed. 
SUMMARY OF THE INVENTION 
According to the present invention a fluid flow control valve comprises a 
resilient tube and a non-return valve mounted within the tube and in which 
the arrangement is such that an external pressure applied to the tube in 
the vicinity of the valve distorts the tube and actuates the valve to an 
open position to permit fluid flow. 
In one embodiment the flexible tube has internal flexible flaps arranged to 
form a "duck bill" non-return valve and in this case opening pressure is 
applied radially to the tube in a direction parallel to the free ends of 
the flaps and slightly downstream of the free ends. 
To identify the correct point of application of the pressure, the outer 
surface of the tube may be marked appropriately or be formed with a small 
excrescence. 
Alternatively, the tube may be mounted in a housing which also accommodates 
an arrangement for applying pressure to the tube at the correct point and 
in the required direction. 
In one embodiment of the invention, the flexible tube is located within a 
rigid sleeve apertured to permit the application of said force to the 
tube. 
Preferably, the flexible tube is formed or provided with locating means 
which ensure correct orientation of the tube when positioned in the 
sleeve. 
The means for applying the force may comprise a button contoured to engage 
and be retained in position by a locating pocket formed externally on the 
sleeve. 
The sleeve and flexible tube may be mounted in a housing which forms a 
handle by which the assembly is held by a user, the housing being 
apertured to provide access to the aperture in the sleeve. The housing may 
also have locating surfaces for ensuring the correct orientation of the 
sleeve within the housing.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
FIGS. 1-3 show the flow control valve itself. A generally tubular one-piece 
component includes a tubular body 1 flanged at one end as at 2 and at the 
other with a larger flange 3 and formed internally with inclined flaps 4, 
5. The flaps 4, 5 are integral with the body 1 being joined thereto at the 
roots and along the sides of the flaps. The ends of the flaps are 
separable along the line 6. Together, the flaps 4, 5 constitute the 
well-known "duck-bill" type non-return valve. 
The body 1 also has an external key 7 formed as an extension of the flange 
2 and positioned to identify the circumferential location of the line 6, 
the end face 7a being radially in line with the line 6. 
Conveniently, the valve is moulded from rubber although other resilient 
materials inert with respect to the liquid or gas whose flow is to be 
controlled may be used. 
As shown in FIGS. 1-3, the free edges of the flaps are normally in contact, 
fluid pressure in the direction of arrow A in FIG. 3 tending to hold the 
edges together and the valve closed whilst fluid pressure in the direction 
of arrow B in FIG. 3 opens the edges to permit flow. 
When used as a flow control valve, the body 1 is inserted in a fluid flow 
line, leakage at the ends of the body being prevented by the flanges 2, 3 
as will be described in more detail below. 
Alternatively, the flanges may be omitted and fluid flow conduits inserted 
in both ends of the body 1 as indicated in FIG. 3. 
By applying pressure to the body 1 in a radial direction parallel to the 
junction line 6 and slightly downstream of the latter (with respect to 
fluid flow in the direction of arrow A) the free ends of the flaps 4, 5 
can be parted so permitting fluid flow in the direction of arrow A. On 
release of the pressure, the free edges move into contact so stopping 
fluid flow, this action being assisted by the fluid pressure acting in the 
direction of arrow A. 
To part the edges and so open the valve, the external pressure must be 
applied at the correct location and this may be indicated on the external 
surface of the body 1 by, for example, a suitably shaped excrescence. 
In one embodiment of the invention, the valve is mounted in a sleeve 8 
shown in FIGS. 4 and 5. The sleeve is also of tubular form, the body 1 of 
the valve being a relatively close fit in the sleeve 8 the bore of which 
is enlarged at one end as at 9. The enlarged portion 9 has a longitudinal 
keyway 10 in which key 7 on the valve locates. The keyway 10 extends 
axially of the sleeve 8 beyond the enlarged portion 9 to provide a pocket 
11 whose function will be described below. The outer wall of the keyway 10 
is cutaway as at 12 whilst the wall of the sleeve is itself cutaway at 13. 
As can be seen from FIG. 5, the overall length of the sleeve 8 is such that 
it locates between the flanges 2 and 3 at the ends of the body 1 of the 
valve and is thereby retained in position on the body 1. 
The sleeve 8 is moulded from a plastics material and is comparatively 
rigid. 
FIG. 6 is a section of a housing of generally cylindrical form with the 
assembly shown in FIGS. 4 and 5 mounted in a through bore located along 
the longitudinal axis of the housing. 
The housing is in two parts 14, 15 screwed together by means of 
co-operating screw threads 16. 
Part 14 has an internal chamber 17 sized to accommodate the assembly shown 
in FIGS. 1 and 5 and having an outlet tube 18 leading from chamber 17. The 
end of the outlet tube 18 is fitted with a rounded nozzle 18a. Surrounding 
the outlet tube 18 is a tubular extension 19 of the part 14, the extension 
forming, with the outlet tube 18, a coupling by means of which the housing 
can be attached to another component. 
The wall of the part 14 is apertured at 20 about midway of the axial length 
of the chamber 17, the aperture being of rectangular form when viewed in 
the direction of arrow C and shown in FIG. 7. The longer sides 20a of the 
rectangle lying at right angles to the longitudinal axis of the housing. 
That side of the rectangle closer to the outlet tube 18 has a small 
rectangular recess 20b in it. 
The chamber 17 is extended, in the vicinity of aperture 20, to accommodate 
the keyway 10 on the sleeve 8. In that way, the sleeve 8 and hence the 
valve is correctly orientated within the part 14 of the housing. 
The aperture 20 is bounded by a continuous wall 21 which, when viewed in 
the direction of arrow C forms a square each side of which is parallel to 
one side of the rectangular aperture 20. 
Positioned inside wall 21 is the square head 22 of a control button whose 
stem 23, of rectangular transverse cross section, terminates in a circular 
bearing extension 24 positioned at one end of the stem 23 as can be seen 
from FIGS. 6 and 8. The upper surface of the head 22 of the control button 
is curved to conform to the tubular shape of the part 14 and the upper 
surface of the transverse parts of the wall 21 are similarly curved. 
When assembled as shown in FIG. 6, the extension 24 locates in the pocket 
11 referred to above and this retains the control button in position. 
Additionally, the small rectangular recess 20b keys the button in its 
correct orientation. 
Located between the mating ends of the parts 14, 15 is the flanged end 25 
of a tubular coupler 26 located in an inlet 27 of part 15, the wall of the 
coupler being spaced somewhat from the surface of the inlet 27 to permit 
the end of an inlet tube 28 to be connected to the coupler 26 as shown. 
The tube 28 passes through part 15 which, as can be seen from FIG. 6 is 
mainly in the form of a tube. 
When the parts 14 and 15 are screwed together the flanges 2 and 3 are 
compressed between the end surfaces of the rigid sleeve 8 and the adjacent 
end of part 14 via the flanged end 25 of coupler 26 the adjacent end of 
part 15. In that way, leakage of fluid is prevented. If necessary to 
increase the fluid-tightness, stress rings or similar surfaces may be 
formed on the end face of the flanges. 
The extension 24 is so positioned relatively to the flaps 4, 5 that when 
the control button is depressed, a radially inwardly acting force is 
applied parallel to line 6 but spaced slightly therefrom towards the roots 
of the flaps. That force distorts the ends of the flaps remote from the 
roots and causes these ends to separate. 
The valve is used to control flow of fluid in the direction of arrow D, 
FIG. 6, the pressure of such fluid acting on the inclined flaps 4, 5 to 
keep the ends thereof lying on line 6 closed so preventing flow from inlet 
27 to outlet tube 18. 
When the control button 22 is depressed the ends of the flaps open and 
fluid flow from inlet 27 to outlet 18 can take place. As soon as the 
button is released, fluid pressure in the inlet 27 acts to close the flap 
ends and the inherent resiliency of the flaps 4, 5 and tube 1 restores the 
control button to the position shown in FIG. 6. 
It may be found desirable, under some conditions of use, to provide 
pressure points or areas that act on the flaps 4, 5 in such manner as to 
urge the free ends together more firmly. Such pressure points or areas may 
be provided by an external thickening of the wall of the tubular body 1 in 
the vicinity of the flaps 4, 5 but over areas diametrically opposed to one 
another and lying on each side of the line 6. Such thickened parts are 
shown in FIG. 3 by the dotted line 29. 
When the flow control valve is inserted into the sleeve 8 inwardly-directed 
forces are created which act on the flaps 4, 5 to close them more firmly. 
It will be appreciated that a similar result could be achieved by forming 
inwardly-extending projections on the inner surface of the sleeve 8 
itself. 
The housing shown in FIG. 6 is suitable for use with a pressurised paint 
supply system that feeds paint from a container (not shown) via tube 28 to 
an applicator (also not shown) that is connected to outlet 18 of part 14 
of the housing. 
It will be appreciated from the foregoing desciption that paint flows to 
the applicator only when the control button 22 is depressed and that 
otherwise the paint pressure in tube 28 keeps the ends of the flaps 4, 5 
tightly closed so preventing leakage. 
It will also be appreciated that the relatively simple structure of the 
valve formed by flaps 4, 5 facilitates cleaning after use. If water 
soluble paints are used, paint remaining in the control valve assembly can 
readily be flushed out merely by connecting outlet tube 18 to a water tap, 
the water pressure forcing apart the ends of the flaps to allow water to 
flow freely from outlet tube 18 to inlet 27 and along the pipe 28 without 
the need to operate the button 22. 
The flow control valve can be used to control the flow of fluids other than 
paints. It could, for example, be used to control the flow of air from a 
hydraulic brake system during a so-called "bleeding" operation. 
It will also be understood that other means than the control button 
described above of applying opening pressure to the ends of the flaps may 
be used. The means must, of course, allow the application of sufficient 
pressure to open the flap ends against the closing pressure they may 
experience from fluid acting on them. Additionally, the flaps must be 
sufficiently rigid to allow them to open against such fluid pressure. If 
the flanges are insufficiently rigid, opening pressure tends to distort 
the entire valve without opening the flap ends.