Fluid logic flip-flop

An improved flip-flop fluid logic circuit device is made from a body block having a through bore and adapted to receive a pair of identical inserts, a composite valve member in between the inserts, pressure responsive diaphragm members for engaging the opposite ends of the valve member to drive the valve between extreme positions within the bore and means for sealing the ends of the bore to retain the operating mechanism. A manual override button is included at each end of the bore to operate the composite valve member.

BACKGROUND OF THE INVENTION 
This invention relates to an improved fluid logic device and more 
particularly to an improved construction for a fluid logic flip-flop 
device. 
Fluid logic devices for control of industrial equipment have become 
increasingly useful recently. Utilization of such devices with pneumatic 
and hydraulic equipment may eliminate the need for electrical control, 
thereby eliminating the potential hazard of electric shock and spark. 
Bouteille in his book "Fluid Logic Controls and Industrial Automation", 
John Wiley and Sons, 1973, reviews the state of the art of fluid logic 
control devices. In the Bouteille book, numerous types of logic devices 
are disclosed including AND, OR or NOT logic devices. Additionally, a 
so-called memory device is disclosed. The memory device is also known as a 
"flip-flop" device. 
The so-called flip-flop device provides an output signal in response to a 
pulse or a constant input signal. In other words, the output remains in 
the "on" state once it has been triggered by an appropriate input signal. 
The output remains constant even though the input is subsequently turned 
"off". A positive cancellation signal is required in order to shift the 
output signal to the "off" position. 
Various structures have been developed to provide the flip-flop function. 
Many of these structures are illustrated in the Bouteille reference. 
Generally, these structures provide a poppet or sliding D valve mounted in 
an elongated bore. FIGS. 3-29, 3-30 and 3-31 of the Bouteille reference 
illustrate various typical embodiments of prior art structures. 
While such prior art structures function well, they are often expensive to 
make. Additionally, the sliding valve members in prior art flip-flop 
devices are subject to wear. Relatively low shifting pressures compared to 
supply pressure may result in false signaling. Often, such prior art 
devices do not have a quick, sharp, snap action feature. Finally, prior 
art devices often require precise machining operations during manufacture. 
This may add significantly to the manufacturing cost of the product. 
SUMMARY OF THE INVENTION 
The present invention comprises an improved fluid logic flip-flop device 
which overcomes many of the disadvantages found in the prior art. The 
flip-flop device of the present invention includes a body with a central 
bore and a plurality of passages into the bore from the outside. A pair of 
opposed substantially identical inserts are positioned in the bore. The 
inserts include various valve seats and passageways. A valve member in the 
shape of a poppet is positioned between the inserts and cooperates with 
the seats of the inserts. A pressure responsive member at each end of the 
bore operates to engage and drive the valve member between various seated 
positions. 
It is thus an object of the present invention to provide a moving part, 
fluid logic flip-flop device which eliminates various disadvantages 
associated with the prior art. 
A further object of the present invention is to provide a fluid logic 
flip-flop device with a sufficiently high shifting pressure threshold to 
prevent inadvertent shifting or actuation of the device due to stray fluid 
pressure pulses in a fluid logic circuit. 
Still another object of the invention is to provide a fluid logic flip-flop 
device with snap acting operation to provide true binary logic pressure 
signals. 
A further object of the present invention is to provide a fluid logic 
flip-flop device which is inexpensive to manufacture, requires little or 
no special machining and may be fabricated by inexpensive molding or other 
processing means. 
These and other objects, advantages and features of the invention will be 
set forth in the detailed description which follows.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
The flip-flop fluid logic device includes a body block or body 10 which is 
a generally rectangular parallelpiped having a flat bottom surface 12 as 
shown in FIG. 3. The body 12 includes a through bore 14 having a 
centerline axis 16 as illustrated in FIG. 2. The bore is generally 
cylindrical and symmetrical about the centerline axis 16, though the 
diameter of the bore 14 varies along the centerline axis as illustrated. 
At the center of the bore 14, the bore has a bore section 14A of minimum 
diameter. The bore sections next adjacent to the bore section 14A are 
sections 14B1 and 14B2 which have equal diameters greater than the 
diameter of section 14A. Continuing on in both directions from the bore 
section 14A, the next adjacent sections of increasing diameter are 
identified as sections 14C1 and 14C2. The diameters of sections 14C1 and 
14C2 are equal. 
Projecting through the wall of the body 10 and extending upward from 
surface 12 is a series of passages arranged in serial order along the axis 
16 and identified as follows: first inlet passage 18, first outlet passage 
20, supply inlet passage 22, second outlet passage 24 and second inlet 
passage 26. A first exhaust passage 28 from the bore 14 extends through 
the side wall 13 of the body 10 and is positioned intermediate first inlet 
18 and first outlet 20 with respect to the axis 16. In similar fashion, a 
second exhaust passage 30 is positioned intermediate second outlet passage 
24 and second inlet passage 26. Note that auxiliary outlets 20A and 24A 
may be provided on the opposite side of body 10 as shown in FIGS. 1 and 2 
for use in place of outlets 20 and 24. Outlets 20A and 24A are threaded to 
accept a plug or tube fittings. 
The center supply inlet passage 22 is connected, by means of a channel 32 
defined in the surface 12, to end circuit board connection positions 34 
and 36 as illustrated in FIG. 3. Each of the inlet and outlet passages 18, 
20, 24 and 26 as well as channel 32 is surrounded by a sealing element 
such as O ring seal 38 which is retained in a counter bore in surface 12. 
Bolts 40 which pass through the body 10 then permit sealing attachment of 
the flip-flop fluid logic device to a circuit board, for example, as shown 
in U.S. Pat. No. 3,407,833 which is incorporated herewith by reference. It 
is also possible to use other connection means with the variously 
described passages to provide fluid circuit connection. 
Inserts 42 and 44 are positioned from opposite ends of the bore 14 to the 
position shown in FIG. 2 within the bore. The inserts 42, 44 are made in 
accordance with the teachings of U.S. Pat. No. 3,990,468 which is 
incorporated herewith by reference. The inserts 42, 44 are thus 
symmetrical about the centerline axis 16. The inserts 42, 44 are 
positioned within the bore 14 so that they appear as a mirror image of 
each other. 
Like numbers will be used to define the like parts of the inserts 42, 44. 
Each insert 42, 44 includes a fluid supply seat 46 and a passage or center 
bore 48 extending from the fluid supply seat 46 along the centerline axis 
16 and through the insert 42, 44. This center passage 48 defines a second 
exhaust valve seat 50 facing in the opposite direction from the fluid 
supply valve seat 46. Note that with regard to positioning of the insert 
44, seat 46 is intermediate supply inlet 22 and outlet 24. With regard to 
insert 42, seat 46 is intermediate a path between inlet 22 and outlet 20. 
For insert 44, the exhaust valve seat 50 is intermediate the outlet 
passage 24 and exhaust passage 30. For insert 42, exhaust valve seat 50 is 
intermediate outlet 20 and exhaust 28. 
A flexible diaphragm member 52 is positioned over the open end of the 
passage 48 of insert 44 so that fluid pressure from the second supply 
inlet 26 may act on the diaphragm 52 causing it to flex. The diaphragm 52 
is held in position against insert 44 by means of the cover plate 54. 
Similarly, diaphragm 53 cooperates with insert 42 and has a cover plate 
55. 
The cover plate 54 also includes a manually actuable override member 56 
positioned in a center bore 58 of the plate 54. The override member 56 
includes an O-ring seal 60 retained in a groove 62 to prevent escape of 
air from chamber 64 defined between the cover plate 54 and the diaphragm 
52. The flange surface 66 of member 56 cooperates with annular land 
surface 68 of the cover plate 54 to retain the override member 56 in 
position and limit the outward travel of that member 56. The outside end 
of the member 56 may be manually actuated against the diaphragm 52 in 
order to override or manually actuate the flip-flop device. 
A composite valve 70 is positioned between the inserts 42 and 44. The valve 
70 is comprised of a center disc portion 72 of a first or major diameter 
substantially equal to or slightly greater than the diameter of the seat 
46. Projecting in opposite directions from the disc 72 along the 
centerline axis 16 are spacing studs 74 and 76. The studs 74 and 76 
terminate respectively with cooperative plunger ends 78 and 80 which 
engage diaphragms 52 and 53, respectively. 
A circumferential groove 82 with an O-ring seal 84 is defined in the stud 
74. The seal 84 cooperates with seat 50 of insert 44. Ring 85 in groove 83 
of stud 76 cooperates with seat 50 of insert 42. 
Radial passages 86 and 88 extend outward from the center of the insert 44 
and connect respectively with exhaust 30 and second fluid outlet passage 
24. Radial passages 86 and 88 of insert 42 connect respectively with 
exhaust 28 and outlet 20. 
The distance between the sealing surfaces 71 and 73 of the disc 72 is 
slightly less than the spacing between seats 46 of the respective inserts 
42 and 44. Valve surface 71 is spaced by means of the stud 74 from the 
valve seal 84 a distance greater than the spacing between seats 46 and 50. 
Valve surface 73 is similarly positoned by stud 76. Note also that the 
active surface area of the valve seat surface 71 is less than the active 
surface area of diaphragm 52. Similarly, the area of surface 73 is less 
than the area of diaphragm 53. 
A plane perpendicular to the axis 16 and passing through the center of the 
supply inlet passage 22 is substantially a mirror plane. Thus, the 
description given for the second insert 44 and associated parts of the 
flip-flop device find their mirror image with regard to the first insert 
42. 
Operation 
In operation, supply fluid is constantly provided at supply inlet passage 
22. A pulse or pressure signal through control inlet 26 forces the 
diaphragm 52 and valve 70 to the left. This is the position shown in FIG. 
2. When in the position shown in FIG. 2, fluid flows from the inlet 22 
past the valve 70 through passage 88 and out passage 24. The exhaust 30 is 
sealed by virtue of the seal 84 engaging the seat 50. The valve 70 is 
maintained in the position shown even if the pulse or fluid control 
pressure is removed from inlet 26. This results because of the active area 
71 which is exposed to fluid pressure from the supply inlet 22. That is, 
pressure on surface 71 maintains the device in configuration illustrated, 
even if pressure is removed from inlet 26. 
To shift the valve to the opposite position or to the right from that shown 
in FIG. 2, fluid control pressure must be removed from port or passage 26 
and a pressure signal must be applied through passage 18. Upon application 
through the passage 18, the pressure engages the surface of diaphragm 53. 
Since the area of the diaphragm 53 is greater than the active surface area 
71, upon reaching a predefined threshold pressure, the valve 70 is shifted 
to the right in FIG. 2. Simultaneously, exhaust 28 is sealed and fluid 
from fluid supply 22 may then pass through pressure outlet 20. The surface 
71 then seats against seat 46 closing off supply through the outlet 24. 
The outlet 24 will then exhaust through passage 88 past seat 50 through 
passage 86 and out the exhaust 30. 
To override or cause manual actuation of the flip-flop device, the member 
56 may be manually depressed. 
Alternative Embodiment 
FIG. 4 illustrates an alternative embodiment for the diaphragm 52, 53. A 
piston member 90 has been substituted for the diaphragm 52, 53. Thus, 
diaphragm 52 of FIG. 2 is replaced by the composite manual actuation 
member and piston member 90 in FIG. 4. The piston member 90 includes a cup 
seal 92 retained in a circumferential groove 94. Fluid pressure through 
inlet 26 acts against the piston member 90 and thence against the end 78 
of the valve 70. Note that in the embodiment of FIG. 4, the manual 
override member 56 is integrally molded with the piston member 90. 
While there has been set forth a preferred embodiment of the present 
invention, it is to be understood that the invention shall be limited only 
by the following claims and their equivalents.