Four-way control valve

A four-way control valve comprises two side by side chambers 130, 132. Each chamber has high and low pressure inlet ports 151, 156, 157, 159 and an outlet port 162, 164. The high and low inlet ports of each chamber are alternately closed by respective flexible vanes 126, 128. The vanes extend through and pivot on walls 135, 137 of the chambers and the opposite ends of the vanes are joined by a linking bar 124. The linking bar is driven by a common actuator such as a solenoid 120. The pressures applied to the inlet ports of the chambers are inverted such that the pressures at the two outlet ports are opposite high and low pressures. The four-way valve may serve as a pilot valve 22 to actuate a higher flow capacity three or four-way diaphragm valve.

CROSS REFERENCE TO RELATED APPLICATION 
Pilot Operated Supply and Waste Control Valve, Ser. No. 602,438, filed Apr. 
20, 1984. 
DESCRIPTION 
1. Technical Field 
The present invention relates to fluid control valves and in particular to 
four-way valves. 
2. Background 
Control valves are widely used to apply high pressure fluid to one or more 
load conduits and thereafter exhaust that fluid from the load conduits. In 
three-way valves, the fluid is alternately supplied to and exhausted from 
a single conduit; in four-way valves, the fluid is supplied to one conduit 
as it is exhausted from another conduit, and thereafter the fluid is 
exhausted from the first conduit and supplied to the second conduit. Such 
valves have many uses, but a primary use is as a directional control valve 
which supplies and exhausts fluid to and from each end of a cylinder to 
drive a piston. As high pressure fluid is applied to a first end of the 
cylinder, it is exhausted from the a second end to drive the piston in a 
first direction. Thereafter, the high pressure fluid is supplied to the 
second end of the cylinder and exhausted from the first to drive the 
piston in the opposite direction. 
Large three and four-way control valves are themselves generally controlled 
by one or more pilot valves. The pilot valves may be three-way or four-way 
valves, and they may be actuated manually, by a fluid, by a solenoid, or 
by any other drive mechanism. 
One form of pilot operated four-way valve is shown in my prior U.S. Pat. 
No. 4,169,490. The valve shown in that patent includes four poppet valves 
which are driven pneumatically through respective diaphragms. The control 
pressures applied to the diaphragms can be obtained from a relatively 
simple pilot valve because a single pressure can be applied to each of the 
four diaphragms. The reverse operation of the valves required to close 
waste valves while supply valves are open and vice versa can be obtained 
by the mechanical arrangement of the poppet valves themselves. A 
disadvantage of poppet valves is that the poppets add to the expense of 
the system. Further, their large mass, relative to diaphragm valves, 
results in harder pounding of the poppet valves and thus increased wear. 
Therefore, in many applications a more simple and smaller mass diaphragm 
valve may be preferred despite the more complicated controls required for 
such systems. 
One form of four-way valve in which the main valve members are diaphragms 
is shown in U.S. Pat. No. 2,911,005 to Adelson. In that system, a first 
pilot valve alternately applies high and low control pressures to the 
back, control faces of one pair of diaphragms. A second pilot valve 
responds to that control pressure to supply a reversed, low or high, 
pressure to the control faces of another pair of diaphragms. A significant 
disadvantage of the Adelson system is that it requires two externally 
supplied pressure levels above the pressure level of the supply fluid to 
operate the second pilot valve and also control the main diaphragm valves. 
Another form of four-way valve wherein the main valving elements are 
diaphragms is shown in U.S. Pat. No. 3,016,918 to Wentworth. The Wentworth 
valve utilizes the pressure of the supply fluid to derive the control 
pressures to be applied behind the diaphragm valves. A disadvantage of the 
Wentworth and similar systems is that they require several flow 
restrictions in the control lines. Where the supply fluid contains foreign 
materials such as sand, grit, gums or varnish, which is generally the case 
in industrial applications, those restrictions are subject to clogging. If 
filter elements are used to clean the supply fluid applied to the control 
network, those filters must be replaced or cleaned periodically. 
Yet another form of pilot operated four-way valve wherein diaphragms are 
used as the main valving elements is shown in U.S. Pat. No. 2,984,257 to 
McCormick et al. In that system the control pressures are also derived 
from the supply fluid. Restrictions in the control network are avoided by 
the use of two separate but similar pilot valves, wherein the pilot valves 
are operated by two separate independent solenoids. A disadvantage of that 
arrangement is that it requires two solenoids, or two other separate 
mechanically applied forces, to actuate these two separate pilot valve 
mechanisms. The two solenoids add to cost, to the complexity of the 
overall system and to maintenance requirements. It is therefore 
advantageous, even where solenoids are used to actuate the pilot valve, to 
provide a system that uses only one solenoid or, if the system is to be 
operated by some manual means, to provide a system that requires only a 
single "operator" to actuate a single pilot valve. 
Yet another form of piloted four-way control valve utilizing diaphragms as 
the main valve elements is shown in U.S. Pat. No. 4,385,639 to Holborow 
and U.S. Pat. No. Re. 29,481 to Larner. In those systems, the control 
pressures are obtained from pilot spool valves. The high control pressures 
are derived from the supply fluid. Sliding parts of spool valves require 
clean fluid because they are prone to "spool" or "disk" sticking due to 
the effects of varnish and fine particulate matter. If filters are used, 
they must be replaced or cleaned periodically. 
DISCLOSURE OF THE INVENTION 
In accordance with principles of the present invention, a four-way control 
valve includes two output pressure chambers, each having high and low 
pressure inlet ports and an outlet port. Each output pressure chamber has 
a valve member which comprises a pivotal arm for alternately closing the 
high and low pressure ports. Pivotal arms are simultaneously driven by a 
common actuator to close the high pressure port to one chamber while 
closing the low pressure port to the other chamber and vice versa. 
In the preferred embodiment, the controlled pressure chambers are 
positioned side by side, and the pivotal arms extend generally parallel 
from the control pressure chambers. The arms are joined by a linking bar 
which is driven by a solenoid or by a pressure responsive element or by 
manual means. The ends of the pivotal arms within the output pressure 
chambers swing between opposing valve seats at high and low pressure 
ports. The positions of the high and low pressure ports in the two 
chambers are inverted relative to each other. 
In one form of the invention, the four-way valve serves as a pilot valve to 
a larger supply and waste control valve. Preferably, all of the main 
valves are diaphragm valves which are controlled by high and low pressures 
applied to the faces of the diaphragms opposite to their valving faces. 
The pilot valve controls the fluid pressure applied to these diaphragm 
faces to open and close a supply diaphragm valve associated with each load 
port while conversely closing and opening a waste diaphragm valve 
associated with each load port.

DESCRIPTION OF PREFERRED EMBODIMENTS 
A four-way control valve embodying this invention is shown in FIGS. 1-5. In 
this case, the valve is controlled by a solenoid coil 120 but it might 
also be operated manually or pneumatically employing a pressure responsive 
element. When the solenoid coil 120 is actuated, it pulls up on its center 
rod 122 to pull up on a bar 124. The bar 124 in turn pushes up on two 
rocker arms 126 and 128. 
As can be seen in FIGS. 3 and 4, the rocker arms 126 and 128 extend into 
respective output pressure chambers 130 and 132 formed in a lower block 
134 and closed by an upper block 136. The rocker arms extend through and 
pivot on walls 135, 137 to those chambers formed on the block 134. The 
output pressure chambers are sealed about the rocker arms by elastomeric 
collars 138 and 140. When the solenoid 120 is relaxed, the rocker arms are 
pivoted by compression springs 142 and 144 to the position shown in the 
figures. Alternatively, a single spring can be positioned around the 
bottom end of the armature 122 to push the bar 124 downward. 
The rocker arms, or vanes, are connected to the arm 124 by respective pins 
146 and 148. These pins are interference fit into the bar 124 but are 
loosely fit in the vanes 126 and 128. With this arrangement, when the 
solenoid is relaxed, the positions of the vanes are determined by the 
springs 142 and 144 and the valve seats against which the vanes are 
pressed independent of the solenoid rod 122. On the other hand, the bar 
124 serves as an equalizing bar which assures that both vanes are pressed 
firmly against their respective lower valve seats when the solenoid is 
actuated. If the linking bar and the rocker arms were rigid and tightly 
joined, proper seating of both bars simultaneously against their 
respective valve seats would be virtually impossible. The first arm to 
contact a valve seat would prevent further pivoting of the other arm and 
would thus prevent the other arm from being firmly seated. This same 
equalization can be accomplished by having flexibility in one or both 
arms, eliminating the need for any other equalization means. 
Porting to the two output pressure chambers 130 and 132 can be best seen in 
FIG. 5. High pressure is applied to a conduit 150 directly into the 
chamber 130 through port 151. High pressure is also applied through a 
vertical conduit 152 in the block 134 and a horizontal conduit 154 in the 
upper block 136 to an upper high pressure port 156 in chamber 132. Thus, 
high pressure ports are located in the bottom of chamber 130 and in the 
top of chamber 132. On the other hand, low pressure ports 157 and 159 are 
vented directly to atmosphere or a lower pressure through a conduit 158 in 
the top of chamber 130 and through a conduit 160 in the bottom of chamber 
132. 
It can be seen from the above that, when the solenoid 120 is relaxed, the 
high pressure port 156 to chamber 132 is closed and chamber 132 is vented 
to atmosphere or other low pressure. Low pressure is therefore applied to 
a first outlet conduit 162. At the same time the low pressure port 157 to 
chamber 130 is closed and high pressure is applied through line 150 to 
that chamber. High pressure is thus applied to a second outlet conduit 
164. When the solenoid is then actuated, the opposite ports to those 
chambers are closed so that high pressure is applied to outlet conduit 162 
and low pressure is applied to outlet conduit 164. 
The use of dual rocker arms in this four-way valve presents several 
advantages. As already noted, the flexible rocker arms or the equalizer 
bar 124 allow both valve members to be firmly seated while using a common 
actuator. Further, rocker arms allow for a simple valve member and 
actuator assembly without the need for sliding parts which are very 
vulnerable to wear, foreign materials in the fluid, and binding. With 
rocker arms, nearly static seals 138 and 140 provide durable, consistent 
sealing of pressure in the chambers. 
One use of the four-way valve of FIGS. 1-5 is as a directional control 
valve for driving a reciprocating piston in a cylinder. In such an 
arrangement, one outlet conduit 162 would be connected to one end of the 
piston cylinder and the other outlet conduit 164 would be connected to the 
opposite end of the cylinder. With high pressure thus applied to one end 
of the cylinder and the fluid vented from the other end of the cylinder, 
the piston would be driven in one direction. Then, with the solenoid, 
pressure responsive element or manual element actuated, the fluid 
pressures applied to the opposite ends of the cylinder would be reversed 
so that the piston would be driven in the opposite direction. 
The valve of FIGS. 1-5 is designed for low flow rates to and from the 
outlet conduits 162 and 164. To handle larger flow rates, the valve of 
FIGS. 1-5 may serve as a pilot valve to a main valve. An example is shown 
in FIG. 6 where all of the main valves are diaphragm valves. The system of 
FIG. 6 is a pilot operated four-way supply and waste control valve. 
FIG. 6 shows the response of the main control valve to a high pressure at 
the outlet port 162 and a low pressure at port 164. In that case, supply 
fluid, which may be hydraulic or pneumatic, is directed from a supply port 
24 to a load port 26. From the port 26, the supply fluid may be applied, 
for example, to one end of a piston cylinder. At the same time, waste 
fluid is vented from a load port 28 to a waste port 30. The port 28 may, 
for example, be connected to the opposite end of a piston cylinder. 
If the control pressures from the pilot valve 22 are reversed, the valving 
of the supply and waste ports to the two load ports 26 and 28 is reversed. 
Specifically, the supply fluid is applied to the port 28, and port 26 is 
vented through a waste port 32. Waste ports 30 and 32 may be connected so 
that the valve operates as a four port control valve with one supply port, 
one waste port and two load ports. 
The main valve assembly comprises a lower main valve block 34 and an upper 
control block 36. The conduits in block 36 are actually three dimensional 
but are shown on a single plane for purposes of illustration. Cross 
non-connections of conduits are indicated by broken lines. 
The blocks 34 and 36 are separated by a gasket 38. Four diaphragms are 
formed in that gasket. They include two supply diaphragms 40 and 42 and 
two waste diaphragms 44 and 46. The positions of those diaphragms are 
controlled by high and low pressures applied to their upper surfaces 
through conduits in the control block 36. For example, as shown in FIG. 6, 
a low pressure is applied to the control chamber 48 behind the diaphragm 
40 and the diaphragm is pushed away from its annular valve seat 50 by the 
higher supply pressure applied to the annulus 52 from the supply port 24. 
The supply fluid is therefore free to flow through a grid 54 into the load 
port 26 and to the load connected to that port. High pressure is applied 
to the control chamber 56 on top of the waste valve 44 associated with the 
load port 26. That high control pressure presses the diaphragm 44 against 
its annular valve seat 58 to close the passage from the port 26 to the 
waste port 32. The diaphragm rests against the grid 54 to minimize stress 
on the diaphragm due to the pressure differential between the control 
chamber 56 and the waste port 32. 
It can be seen that the supply and waste valves associated with load port 
28 are operated conversely to those associated with port 26. Thus, high 
pressure is applied to the control chamber 62 to close that supply 
diaphragm valve, and low pressure is applied to the control chamber 64 on 
top of diaphragm 46 to open that waste valve. When the control pressures 
from pilot valve 22 are reversed, the supply diaphragm valve to port 26 is 
closed while the waste diaphragm valve from port 26 is open, and the 
supply diaphragm valve to port 28 is open while the waste diaphragm valve 
from that port is closed. 
The derivation of the "ram elevated" control pressures will now be 
described. It should first be noted that the valve shown in FIG. 6 is 
self-powered in that the control pressures are ambient pressure and a high 
pressure obtained from the supply fluid applied to port 24. To that end, a 
ram nozzle 66 is directed into the supply fluid at a point. The resultant 
pressure in the high pressure control conduit 150 is higher than that at 
the supply port 24 by a ram pressure .DELTA.P. The ram pressure .DELTA.P 
can be defined by the following function: 
EQU .DELTA.P=1/2(Q/A.sub.T).sup.2 (.rho./g) (1) 
where Q is the supply fluid flow at an absolute pressure Pa, A.sub.T is the 
total flow area of supply fluid at the end of the ram nozzle, .rho. is the 
fluid density at Pa and g is acceleration due to gravity. The ram elevated 
pressure Pa+.DELTA.P obtained in the ram nozzle 66 is applied to port 150 
of the pilot valve and then throughout the control conduits. The higher 
pressure is also applied to selected control chambers to actuate the 
diaphragm valves. 
In a typical case, the system of FIG. 6 might provide a flow rate of 590 
cubic inches per second through a flow area A.sub.T of 0.2 square inches 
where the absolute pressure of the supply fluid is 99.7 pounds per square 
inch. From equation 1, where the supply fluid is air: 
##EQU1## 
Thus, the control pressure applied to the diaphragms exceeds the supply 
pressure by at least three pounds per square inch to assure adequate 
seating of the diaphragms against the valve seats. 
Several notable features of the valve of FIG. 6 contribute to the reliable, 
self-powered nature of the piloted control. A control pressure higher than 
the supply pressure is obtained by the ram nozzle. All control conduits 
have substantial bores; no restrictions in those conduits are required. 
The system has no sliding parts. Further, only two pressure levels are 
required, the higher supply pressure and low, ambient pressure. No 
additional pressures, which would complicate the system, are required to 
actuate the four main diaphragm valves. 
While the invention has been particularly shown and described with 
reference to a preferred embodiment thereof, it will be understood by 
those skilled in the art that various changes in form and details may be 
made therein without departing from the spirit and scope of the invention 
as defined by the appended claims. For example, any form of actuator could 
be used to operate the valve. Also, the main valves function equally well 
when the flow paths in an annulus and the associated inner valving port 
are interchanged. Further, the main diaphragm valve can be modified 
according to teachings in my U.S. patent application entitled Pilot 
Operated Supply and Waste Control Valve Ser. No. 602,438, filed Apr. 20, 
1984.