Diaphragm multi-port valve assembly

A diaphragm multi-port valve assembly particularly for controlling cylinder and piston assemblies. The valve assembly has communicating chambers which are normally separated by a diaphragm, the chambers being connected by a bleed so that the pressures in the two chambers can equalize. Each chamber is connected to or separated from an appropriate port or other chamber by a pilot valve.

BACKGROUND OF THE INVENTION 
The present invention relates to multi-port valve assemblies particularly, 
but not exclusively, for controlling cylinder and piston assemblies. 
SUMMARY OF THE INVENTION 
According to the present invention there is provided a diaphragm valve 
assembly comprising a first and a second diaphragm valve each comprising a 
first and a second chamber separated by a diaphragm, a valve port for 
communication with the first chamber and normally closed by the diaphragm, 
bleed means connecting the first and second chambers, and control means 
for actuating the valves, wherein the first chamber of the first valve has 
an inlet for communication with a supply of fluid under pressure, the port 
of the first valve is adapted for connection to apparatus to be controlled 
by fluid under pressure and is connected to the first chamber of the 
second valve, the port of the second valve is adapted for connection to 
exhaust, and the second chambers of the valves are connected to the 
control means which is placeable in at least two conditions in a first of 
which the pressure in the second chamber of the first valve will be 
reduced relative to that in the first chamber to permit the diaphragm of 
the first valve to lift to open the port thereof and in a second of which 
the pressure in the second chamber of the second valve will be reduced 
relative to that in the first chamber to permit the diaphragm of the 
second valve to lift to open the port thereof. 
Advantageously, in the first condition of the control means the second 
chambers of the valves are placed in communication and in the second 
condition of the control means the second chambers are isolated from each 
other and the second chamber of the second valve is connected to a path 
for fluid from the assembly. 
In a preferred embodiment the bleed means comprise at least one aperture 
through the diaphragm. Advantageously the bleed means of the second valve 
provides a faster bleed blow than the bleed means of the first valve.

As shown in FIGS. 1 and 2, a three port pneumatic valve assembly, for 
example for operating a single acting cylinder, comprises three 
cylindrical body members 1, 2 and 3 which are held together by bolts (not 
shown) extending through suitably located co-axial apertures (not shown) 
in the members. The members 1 to 3 define two diaphragm valves 4, 5 of 
which each comprises a first chamber 41, 51, a second chamber 42, 52 
separated from the first chamber by a diaphragm 43, 53, and a port 44, 54 
for communication with the first chamber and normally closed by the 
diaphragm. The first chamber 41 of the first valve 4 communicates via a 
duct 6 with an inlet port 7 which is adapted for connection to a supply of 
air under pressure. The port 44 communicates via a duct 8 with a cylinder 
port 9 for connection to the cylinder and via a duct 10, branching from 
duct 8, with the first chamber 51 of the second valve 5. The port 54 of 
the second valve 5 communicates via a duct 11 with an exhaust port 12 
providing a return path for air from the cylinder. 
The second chambers 42, 52 of the valves are connected to a pilot valve 13 
which is placeable in three conditions, in a first of which the second 
chambers 42, 52 are placed in communication, in a second of which the 
second chambers are isolated from each other and the second chamber 52 is 
connected to exhaust, and in a third of which the second chambers are 
isolated from each other and from exhaust. The construction and operation 
of the pilot valve will be described hereafter. 
Each valve 4, 5 includes bleed means placing the two chambers 41, 42 and 
51, 52 of each valve in communication. The bleed means may, as shown, take 
the form of one or more passageways 46, 56 in the diaphragm. However, it 
will be appreciated tht the bleed means could alternatively be provided by 
ducts through the body members and opening into the chambers. 
As shown, each diaphragm 43, 53 has a central thickened portion 43a, 53a 
which is relatively rigid and by which the port 44, 54 is closed, and a 
peripheral bead 43b, 53b which is received in corresponding annular 
recesses in the mating faces of the body members 1 and 2 and 2 and 3 and 
by which the junction between the body members is sealed. The annular 
portion 43c, 53c of each diaphragm between the bead and the thickened 
portion is planar and flexible. Each diaphragm may be made of rubber with 
the central thickened portion rigidified by a nylon disc insert. 
Alternatively, as shown in FIG. 4, the annular flexible portion 63c of 
each diaphragm between the bead 63b and thickened central portion 63a may 
have a U-section. The bleed passageways may be formed, as shown, directly 
in the diaphragm or may be formed in an insert, e.g. of stainless steel, 
bonded into the diaphragm. Each bleed passageway may be provided with a 
filter cap to prevent blocking of the passageway in the event that the 
pressurised fluid is dirty. 
The pilot valve 13 may take the form shown in FIGS. 5 and 6. This valve 
comprises a fixed body 20 having a through-bore 21 and externally 
threaded. A spindle 22 is slidably received in the bore in the body and 
has a blind bore 23 opening at one end 24. The closed end of the bore 23 
has an elongate radial opening 25. Beyond the closed end of the bore 23, 
the spindle is of reduced section and terminates in a frusto conical valve 
member 26 which seats against an annular seal 27 in the corresponding end 
of the body 20. The spindle 22 is biased in a direction to seat the valve 
member 26 by a spring 28 acting between the other end of the body 20 and a 
circlip 29 engaged on the corresponding end of the spindle. The body 20 is 
provided with a radial bore 30 communicating with an internal groove 31 
which permits communication between the bore 30 and the opening 25 in all 
angular and axial operative positions of the spindle 22. 
As shown in FIGS. 1 and 2 of the above described pilot valve 13 is screwed 
into a bore 32 in the end of the second chamber 42 of the first valve 4 
with the valve member 26 facing the chamber 42. The radial bore 30 in the 
body 20 is connected via a duct 33 with the second chamber 52 of the 
second valve 5 and the open end 24 of the blind bore 23 communicates with 
a further chamber 34 formed in the end of the body member 3 and connected 
via a duct 38 to the atmosphere. 
The operation of the above described assembly with port 9 connected to 
chamber 14 (FIGS. 3a, 3b and 3c) of a single acting cylinder 15 is as 
follows. To maintain the piston of the cylinder in a fixed position, the 
pilot valve 13 is placed in the condition shown in FIG. 5 and with the end 
24 of the bore 23 in the spindle closed (FIG. 3a), the closed condition of 
the spindle bore being indicated schematically by a transverse line in 
FIG. 3a, its open condition by an arrow in FIG. 3b. With the pilot valve 
in this condition, the two second chambers 42, 52 are isolated from each 
other and from exhaust to atmosphere. The pressures in the first and 
second chamber of each valve are equal because of the presence of the 
bleed passageways so that both diaphragms maintain the corresponding ports 
44 and 54 closed. No air will therefore flow through the system. To drive 
the piston towards the left hand side, as shown in FIGS. 3c, the pilot 
valve is moved to a condition shown in FIG. 6 and the end 24 of the bore 
23 is maintained closed so that the two second chambers 42, 52 are placed 
in communication with each other (FIG. 3c). Air from the chamber 42 flows 
through the pilot valve and duct 33 into chamber 52, which is initially at 
a lower pressure, to reduce the pressure in chamber 42. The forces on the 
diaphragm 43 are therefore no longer balanced so that the diaphragm lifts 
under the inlet air pressure in chamber 41 to place port 44 in 
communication with chamber 41 as shown in FIG. 3c. Air from the inlet will 
then flow through port 44 and duct 8 to the cylinder. At the same time air 
bleeds through the diaphragm 43 into chamber 42 and flows via duct 33 to 
chamber 52, via the bleed passageways in diaphragm 53 to chamber 51 and 
via ducts 10 and 8 to the cylinder. To prevent undue build up of pressure 
in chamber 52, which would cause the first valve to close, a faster bleed 
rate of flow is provided through diaphragm 53 than through diaphragm 43. 
This may be obtained by providing more passageways in diaphragm 53 or 
providing one or more larger passageways. To halt the flow of air to the 
cylinder, communication between chambers 42 and 52 is closed by moving the 
valve 13 back to its initial condition (FIG. 3a). As soon as this occurs 
the pressures on the faces of the diaphragms 43 and 53 equalize because of 
the presence of the bleed passageways and the port 44 is therefore closed 
by the diaphragm 43. 
To permit the piston to move in the opposite direction, the pilot valve is 
placed in the condition shown in FIG. 5 but with the end 24 of bore 23 
open. In this condition, while the chambers 42, 52 are isolated from each 
other, chamber 52 is open to exhaust (FIG. 3b). The pressure in this 
chamber is therefore reduced which allows diaphragm 53 to lift under the 
pressure of air in the cylinder to place the port 54 in communication with 
chamber 51 and thereby the cylinder in communication with exhaust. It will 
be appreciated that the movement of the piston can be controlled by 
varying the degree of opening of the bore 23 to exhaust. Flow of air from 
the cylinder ceases as soon as the valve 13 is returned to its initial 
condition. Thereupon the pressure across the diaphragm 53 equalizes by 
flow of air through the bleed passageways so that the diaphragm 53 returns 
to its position closing port 54. 
It will be appreciated that the pilot valve may be actuated in a number of 
different ways, it merely being necessary for the actuator to be such as 
can close the end 24 of the bore 23 of the spindle. The actuation may be 
pneumatic, hydraulic, electrical or manual. If electrically actuated, the 
actuation may be effected by a solenoid whose armature acts on the spindle 
of the valve both to move the spindle and to close the open end 24 of the 
bore. A form of pneumatic actuation is shown in FIGS. 1 and 2 in which the 
valve 13 is actuated by a diaphragm 35, similar to the diaphragms 43 and 
53 except that it does not include bleed passageways. The diaphragm 35 is 
located between the end of member 3 and a fourth body member 36 which is 
bolted to members 1 to 3. The diaphragm 35 separates the chamber 34 from a 
control chamber 37 connected via a duct 38 to a control port 39. Air is 
supplied to the control port 39 either to provide a coarse control in 
which the valve 13 is only placeable in the two conditions illustrated in 
FIGS. 3 b and 3c or to provide a fine control by which the valve is also 
placeable in the condition shown in FIG. 3a and the extent of opening of 
the end 24 of the bore of the pilot valve spindle may also be controlled. 
It will also be appreciated that the above described pilot valve 13 may be 
replaced by any other type of control valve which is placeable in at least 
the two conditions illustrated in FIGS. 3b and 3c. 
The above described assembly may be duplicated and used to control a double 
acting cylinder. Such a control may be effected simply by providing two 
valve assemblies as above described, each with its own control means, and 
with a common or two associated control means actuators. Alternatively 
such a double valve assembly may be as shown in FIGS. 7 to 10. As shown in 
FIGS. 7 to 9, the two pairs of valves 4a, 5a and 4b, 5b are defined 
between two rectangular blocks 60, 61 which are bolted together. One block 
60 defines the four first chambers 41a, 51a and 41b, 51b and ports 44a and 
54a and the other block 61 defines the four second chambers 42a, 52a and 
42b, 52b. The diaphragms 43a, 53a and 43b, 53b may be provided 
individually as in the preceding embodiment or as modifed in FIG. 4, or 
may be molded as a single component as shown in FIG. 9. 
The first chambers 41a and 41b of the two first valves have a common inlet 
port 7 but otherwise the first chambers and ports of the pairs of valves 
are connected together as previously described. The second chambers of the 
four valves are also connected in pairs as previously described, each pair 
to a pilot valve 13a13b. 
The various conditions of operation of the above described assembly are 
illustrated in FIGS. 10a to 10g where the assembly is shown connected to a 
double acting cylinder 22, valves 4a and 5a controlling the supply of air 
to chamber 63 of the cylinder and valves 4b and 5b being connected to 
control the supply of air to the other chamber 64. FIG. 10a illustrates 
the situation where both pilot valves 13a and 13b are in the condition 
shown in FIG. 3a in which no air will flow through the system and the 
piston is maintained in position. In FIG. 10c the pilot valve 13a is in 
the condition shown in FIG. 3b and the pilot valve 13b is in the condition 
shown in FIG. 3c. In this condition pressurized air will flow through 
valve 4b into chamber 64 of the cylinder and will be exhausted from 
chamber 63 via valve 5a to drive the piston to the left hand side of FIG. 
10c. This condition may be immediately preceded by one as shown in FIG. 
10b in which the pilot valve 13b is in the condition shown in FIG. 3c but 
the pilot valve 13a is still in the condition shown in FIG. 3a (or as 
shown in FIG. 10a) in which exhaust of chamber 63 is blocked so that the 
piston is cushioned. Thereafter the connection of pilot valve 13a to 
exhaust (FIG. 10c) may be controlled to control the movement of the piston 
towards the left hand side as shown in FIG. 10c. In FIG. 10e the valve 13a 
is in the condition shown in FIG. 3c and the valve 13b is in the condition 
shown in FIG. 3b so that the piston will be driven to the right hand side 
of FIG. 10e, pressurised air being supplied to chamber 63 via valve 4a and 
being exhausted from chamber 64 via valve 5b. Again this condition may be 
immediately preceded by one as shown in FIG. 10d in which the piston is 
cushioned and thereafter movement of the piston may be controlled. In FIG. 
10f both pilot valves are in the condition shown in FIG. 3c so that both 
chambers 63 and 64 of the cylinder are connected to the pressurised air 
supply. In FIG. 10g both pilot valves are in the condition shown in FIG. 
3b so that both chambers of the cylinder are connected to exhaust. 
The pilot valves 13a, 13b are advantageously operated by a single actuator, 
for example as shown in FIGS. 11 to 14. In FIGS. 11 and 12 the pilot 
valves 13a, 13b are arranged in the body 61 in spaced parallel orientation 
for operation manually by a bar 65 which is mounted in a recess 66 in the 
top of body 61 for pivotal movement about a pin 67. The bar is normally in 
a position closing the ends 24 of the spindles of both valves and the 
assembly is thus in the condition shown in FIG. 10a. The assembly can be 
placed in the condition shown in FIG. 10c by tilting the bar 65 clockwise 
and can be placed in the condition shown in FIG. 10e by tilting the bar 
anti-clockwise. Preferably the bar 65 is made flexible so that both arms 
can be simultaneously depressed to place the assembly in the condition 
shown in FIG. 10f. 
In FIGS. 13 and 14, the top of body 61 is provided with a cylindrical 
recess 68 for receiving a solenoid (not shown) whose armature is aligned 
with the two co-axial pilot valves 13a, 13b. The solenoid is arranged so 
that normally it closes the end 24 of the spindles of both valves, placing 
the assembly in the condition shown in FIG. 10a. Energization of the 
solenoid to move the armature to the left or right hand side produces the 
condition of FIG. 10a or FIG. 10c in the assembly. This arrangement using 
a solenoid actuator for the pilot valve 13a, 13b does not allow the 
possibility of placing the assembly in the condition of FIG. 10f. This 
possibility could be provided for by replacing the solenoid with a single 
armature by one with a pair of armatures which can either move together to 
produce the conditions of FIGS. 10a, 10c and 10e or can be moved in 
opposite directions to produce the conditions shown in FIG. 10f and 10g. 
Such an actuator may also be controlled so as to produce the conditions of 
FIGS. 10b and 10d. 
It will be noted that in FIGS. 11 to 14 the paths of the various ducts 
connecting the second chambers to the pilot valves have not been shown. It 
will be appreciated that these paths can be located howsoever is most 
convenient, it merely being necessary for the second chambers 52a, 52b to 
be connected to the ends of the respective pilot valves provided with the 
valve members 26 and the second chambers 52a, 52b to pg,12 be connected 
to the radial bores 30 (not shown in FIGS. 12 and 14). 
While the above five port valve assembly is described as having a common 
inlet port 7, it will be appreciated that two inlet ports may be provided, 
one connected to each first chamber of each first valve, and for 
connection, for example, to fluid supplies at different pressures. Such a 
valve assembly will of course be a six port valve assembly. Equally each 
of the above valve assemblies may be provided with a single exhaust port 
connected to the ports of the second valves, instead of the separate 
exhaust ports shown, so making the assemblies four and five port valve 
assemblies. 
It will be appreciated that a three port valve assembly may be constructed 
with the valve diaphragms coplanar as in the above described five port 
valve assembly. 
The above described valve assemblies may be cheap and are simple to 
manufacture because they can be made of plastics material. They have a 
fast response time and are economic in their usage of pressurized fluid 
because effectively the only fluid exhausted is that in the cylinder. They 
are also highly controllable and can provide a metering control as well as 
a simple on-off control. 
It will be appreciated that three or more pairs of valves may be associated 
to control a more complex cylinder and piston assembly. 
The body members of the above described valve assemblies may be made of 
metal, as is conventional, or may be molded of plastics. 
While the above assemblies have been described in terms of controlling 
pressurized air flow, it will be appreciated that they are equally 
suitable for controlling flow of hydraulic fluid.