A fluid-powered actuator has a piston slidably mounted in a cylinder. The piston subdivides the cylinder into first and second end chambers. A plurality of solenoid valves are arranged to selectively inject fuel and oxidizer into either chamber, or to inject liquid oxidizer to react with a solid fuel. Upon contact with one another, the fuel and oxidizer undergo a hypergolic reaction, and the products of this reaction create a pressure sufficient to displace the piston. Alternatively, a mono-propellant fluid fuel may be injected into such chamber. Upon contact with a catalyst in the chamber, the fuel undergoes a disassociation reaction, and the products thereof may be used to displace the piston.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates generally to the field of actuators for selectively 
moving one member relative to another, and, more particularly, to an 
improved actuator which uses either the products of a hypergolic reaction 
between a suitable solid or liquid fuel and an oxidizer, or the products 
of a disassociation reaction between a suitable mono-propellant fuel and a 
catalyst, to selectively move a valve member relative to its seat. 
2. Description of the Prior Art 
Actuators abound in many different forms, and are used for many different 
purposes. Such actuators may be fluid-powered (as in the case of a 
piston-and-cylinder), or electro-mechanical (as in the case of a solenoid, 
a force motor, or a torque motor). It is, of course, well known to use 
such actuators to move a valve element relative to an associated seat. 
However, in the field of rocketry and spacecraft, weight is a primary 
consideration. While actuators may be miniaturized in an attempt to reduce 
their weight and size, such actuators must also have the capability of 
creating a force sufficient to displace an applied load. In general, the 
greater the applied load, the larger and heavier the actuator and any 
associated valve. Such vehicles typically have a plurality of rocket 
engines, which are used to either propel the vehicle or to control its 
attitude during flight (e.g., thrusters). 
It is well known to supply a suitable fuel and oxidizer to a hypergolic 
rocket engine. When such fuel and oxidizer are mixed together, they 
undergo a hypergolic reaction, and the products thereof create thrust. It 
is also known to supply a suitable mono-propellant fuel to a rocket 
engine, which incorporates a suitable triggering catalyst. Upon contact 
with the catalyst, the fuel undergoes a disassociation reaction, and the 
products thereof are also used to create thrust. In controlling the 
operation of these engines, it is necessary to control the flow of the 
serviced fluid(s) supplied thereto. 
SUMMARY OF THE INVENTION 
The present invention provides an improved actuator which may be used to 
control the movement of one member (e.g., a valve member) relative to 
another member (e.g., a valve seat). 
In one form, the actuator is adapted to be associated with sources of a 
suitable oxidizer and fuel (preferably in fluid form), the oxidizer and 
fuel undergoing a hypergolic reaction upon contact with one another. In 
this form, the improved actuator broadly includes: a cavity having a first 
surface; a member mounted in this cavity for movement toward and away from 
the first surface, and forming a first chamber between the member and the 
first surface; a first valve communicating with the source of fuel, and 
operatively arranged to selectively admit fuel to the first chamber; a 
second valve communicating with the source of oxidizer, and operatively 
arranged to selectively admit oxidizer to the first chamber; whereby, when 
the first and second valves are opened simultaneously, the products of the 
resulting hypergolic reaction in the first chamber will cause the member 
to move away from the first surface. 
In another form, the improved actuator is adapted to be associated with a 
source of mono-propellant fluid fuel. In this form, the improved actuator 
comprises: a cavity having a first surface; a member mounted in this 
cylinder for movement toward and away from the first surface and forming a 
first chamber between the member and the first surface; a first catalyst 
arranged in the first chamber, this being capable of reacting with the 
fuel admitted to the first chamber for causing the fuel to disassociate; 
and a first valve communicating with the propellant source and operatively 
arranged to selectively admit fuel to the first chamber; whereby, when the 
first valve is opened, fuel will enter the first chamber and will react 
with the catalyst, and the products of the resulting disassociation 
reaction will move the piston away from the first surface. 
Accordingly, the general object of the invention is to provide an improved 
actuator. 
Another object is to provide an improved actuator which uses the products 
of a hypergolic reaction between a suitable solid or fluid fuel and a 
suitable oxidizer to move one member relative to another. 
Another object is to provide an improved actuator which uses the products 
of a disassociation reaction between a suitable mono-propellant fuel and a 
catalyst, to move one member relative to another. 
Still another object is to provide an improved propellant-actuated valve 
for controlling the flow(s) of fuel and/or oxidizer to a rocket engine. 
These and other objects and advantages will become apparent from the 
foregoing and ongoing written specification, the drawings, and the 
appended claims.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
At the outset, it should be clearly understood that like reference numerals 
are intended to identify the same structural elements, portions or 
surfaces consistently throughout the several drawing figures, as such 
elements, portions or surfaces may be further described or explained by 
the entire written specification, of which this detailed description is an 
integral part. Unless otherwise indicated, the drawings are intended to be 
read (e.g., cross-hatching, arrangement of parts, etc.) together with the 
specification, and are to be considered a portion of the entire "written 
description" of this invention, as required by 35 U.S.C. .sctn.112. As 
used in the following description, the terms "horizontal", "vertical", 
"left", "right", "up" and "down", as well as adjectival and adverbial 
derivatives thereof (e.g., "horizontally", "rightwardly", "upwardly", 
etc.), refer to the orientation of the illustrated structure as the 
particular drawing figure faces the reader. Similarly, the terms 
"inwardly" and "outwardly" refer to the orientation of a surface of 
revolution relative to its axis. As used herein, the term "fluid" 
encompasses both a liquid and a gas. 
Referring now to the drawings, this invention broadly provides an improved 
actuator, of which several embodiments are disclosed. The actuator may use 
the products of a hypergolic reaction, which results when a suitable fuel 
and oxidizer are mixed together, to move one member relative to another. 
Alternatively, the actuator may use the products of a disassociation 
reaction between a mono-propellant fluid fuel and a catalyst, to 
selectively move one member relative to another. The improved actuator 
may, for example, be used to selectively displace a valve member toward 
and away from a seat. However, it should be clearly understood that this 
particular application is merely illustrative, and that the improved 
actuator may be used for many diverse and varied purposes. 
Several embodiments of the improved actuator, and the hypergolic and 
catalystic forms of each, will be described seriatim herebelow. 
First Embodiment (FIGS. 1a-1b) 
Referring now to FIGS. 1a and 1b, an improved valve assembly, generally 
indicated at 10, is schematically shown as including a leftward valve 
portion 11 and a rightward actuator portion 12. 
The valve portion 11 is shown as having a vertically-elongated rectangular 
body 13 provided with internal upper and lower rectangular chambers 14,15, 
respectively. A vertical hole 16 communicates upper chamber 14 with a 
source (not shown) of pressurized fluid fuel via a conduit 18. Another 
vertical hole 19 communicates lower chamber 15 with a source (not shown) 
of pressurized fluid oxidizer via a conduit 20. Horizontal holes 21,22 
communicate chambers 14,15, respectively, with a suitable device (not 
shown), such as a hypergolic rocket engine, via appropriate conduits (not 
shown). A rightwardly-facing circular vertical seat 23 is formed where 
outlet hole 21 opens into upper recess 14. Similarly, another 
rightwardly-facing circular vertical seat 24 is formed where outlet hole 
22 opens into lower recess 15. 
A valve member is mounted in each body chamber for horizontal movement 
toward and away from the associated seat. Thus, the upper member 25 is 
mounted for movement relative to seat 23, while the lower member 26 is 
mounted for movement relative to seat 24. Each of these members has a 
leftwardly- and outwardly-facing frusto-conical surface arranged to 
selectively engage the associated seat to prevent flow from the chamber 
inlet to the chamber outlet, as shown in FIG. 1a. However, both members 
may be moved rightwardly relative to the body, to the position shown in 
FIG. 1b, to permit flow from the associated chamber inlet to the 
associated chamber outlet. 
Members 25,26 are connected to a common vertical bar 28 for simultaneous 
horizontal movement toward or away from their associated seats. To this 
end, upper and lower rods 29,30 have their rightward marginal end portions 
suitably secured to bar 28, have their intermediate portions sealingly and 
slidably penetrating appropriate body holes, and have their leftward 
marginal end portions secured to the upper and lower members 25,26, 
respectively. Annular grooves are shown as extending radially into the 
body from these body holes to accommodate suitable O-rings or the like, 
which seal the rod penetrant portions to the body while permitting 
relative sliding movement therebetween. The fuel and oxidizer undergo a 
hypergolic reaction when mixed together. Examples of such fuel include 
50/50 unsymmetrical dimethylhydrazine, hydrazine, and 
mono-methylhydrazine, while the oxidizer may be nitrogen tetroxide, fuming 
nitric acid, or the like. Other fuels and oxidizers may be used. 
The actuator portion comprises a cylinder which includes a 
horizontally-elongated cylindrical tube 31. The left and right ends of 
this tube are closed by disk-like left and right end caps 32,33, 
respectively. Each of these end caps is sealingly secured to the 
intermediate tube portion 31 by suitable means (not shown). Thus, the end 
cap-tube-end cap subassembly forms an internal chamber defined by left and 
right substantially-circular vertical end surfaces 34,35, and an 
inwardly-facing horizontal cylindrical surface 36. The cylindrical tube is 
provided with a plurality of radial first vent openings, severally 
indicated at 38, and a plurality of radial second vent openings, severally 
indicated at 39. The several first vent openings are arranged in a ring 
and spaced equally about the cylindrical tube, and are spaced axially from 
the similar ring of second vent openings. 
A piston 40 is mounted within the cylinder for horizontal sliding movement 
therealong toward and away from end surfaces 34,35. Piston 40 therefore 
subdivides the cylinder into a leftward first chamber 41 between the 
piston and the left end surface 34, and a rightward second chamber 42 
between the piston and the right end surface 35. A horizontal rod 43 has 
its left marginal end portion suitably secured to bar 28, has an 
intermediate portion sealingly penetrating an axial hole provided through 
left end cap 32, and has its right marginal end portion secured to piston 
40. Thus, piston 40 and valve members 25,26 are constrained to move 
horizontally together between the extreme leftward position shown in FIG. 
1a, at which members 25,26 engage seats 23,24, respectively, and the 
extreme rightward position shown in FIG. 1b, at which these members engage 
the leftwardly-facing vertical surfaces of chambers 14,15. 
Four electrically-operated valves 44,45,46,48 are mounted on the actuator 
portion. If desired, these may be miniature on-off solenoid valves. The 
first valve 44 is mounted on the left end cap, and receives fuel from 
conduit 18 via series-connected conduits 49,50. The second valve 45 is 
also mounted on the left end cap, and receives oxidizer from conduit 20 
via series-connected conduits 51,52. Conversely, third valve 46 is mounted 
on the right end cap and receives fuel from conduit 18 via 
series-connected conduits 49,53. The fourth valve 48 is also mounted on 
the right end cap, but receives oxidizer from conduit 20 via 
series-connected conduits 51,54. Each of these valves is normally-closed. 
The first and second valves 44,45 may be simultaneously opened, as one 
cooperative pair, to spray minute quantities of fuel and oxidizer into 
first chamber 41. When this occurs, the fuel and oxidizer undergo a 
hypergolic reaction upon contact with one another, and the products of 
such reaction create a pressure in chamber 41 which drives the piston 
rightwardly. Initially, such reaction products are confined to the 
expanding first chamber. However, as shown in FIG. 1b, when the 
rightwardly-moving piston passes by, and uncovers, first vent openings 38, 
such reaction products will thereafter be vented from the first chamber. 
When the piston is in its rightward position, as shown in FIG. 1b, third 
and fourth valves 46,48 may be simultaneously opened, as another 
cooperative pair, to spray minute quantities of fuel and oxidizer into the 
second chamber. Here again, the fuel and oxidizer undergo a hypergolic 
reaction upon contact with one another in the second chamber, and thr 
products of such reaction create a pressure in chamber 42 which drives the 
piston leftwardly. When the piston is in the position shown in FIG. 1b, 
the piston covers second vent openings 39, thereby initially confining the 
products of such reaction to the second chamber. However, as the piston 
moves leftwardly, the second vent openings 39 will be uncovered, thereby 
allowing such reaction products to be vented from the second chamber. 
Persons skilled in this art will appreciate that the first and second 
valves 44,45, and the third and fourth valves, 46,48, need only be opened 
momentarily to admit minute quantities of fuel and oxidizer to the 
appropriate chamber. These two cooperative pairs of valves may therefore 
be operated alternatively to selectively displace the piston either 
leftwardly or rightwardly relative to the cylinder, as desired. Moreover, 
when the improved actuator is used to control the operation of a valve 
portion, which in turn controls the flow of fuel and oxidizer to, say, a 
hypergolic rocket engine (not shown), only minute quantities of such 
serviced fluids need be tapped-off and used to operate the improved 
actuator. The fluid(s) controlled by the valve portion may, of course, be 
other than the bi-propellant fuel and oxidizer. 
Persons skilled in this art will readily appreciate that while the 
foregoing embodiment uses the products of a hypergolic reaction between a 
fuel and oxidizer to selectively displace the piston relative to the 
cylinder, a similar result might also be obtained by using the products of 
a disassociation reaction between a suitabel mono-propellant fuel and a 
catalyst. To do this, an appropriate catalyst bed (or solid fuel), such as 
shown in phantom and indicated at 55, would be placed in each of chambers 
41,42. Oxidizer valves 45,48 would then be unnecessary, and could be 
eliminated. One or more valves, such as valves 44,46, could be selectively 
operated to admit minute quantities of a suitable mono-propellant fuel to 
the appropriate chamber. Upon contact with the catalyst bed, the fuel 
would disassociate, and the products of this reaction would be used to 
drive the piston either leftwardly or rightwardly relative to the 
cylinder, as desired. 
Second Embodiment (FIGS. 2a and 2b) 
A second embodiment of the improved actuator, generally indicated at 56 in 
FIGS. 2a-2b, is schematically shown as including a leftward actuator 
portion 58, and a rightward valve portion 59, both mounted within a common 
body 60. 
The body has a leftward cavity bounded by a rightwardly-facing annular 
vertical surface 61, a leftwardly-facing annular vertical surface 62, and 
an inwardly-facing horizontal cylindrical surface 63. A piston 64 is 
mounted within this body cavity for horizontal sliding movement 
therealong. Hemispherical recesses extend into the piston from its left 
and right faces, and these recesses are arranged to face other cooperative 
recesses provided in the body. Thus, the piston subdivides this body 
cavity into a leftward or first chamber 65, and a rightward or second 
chamber 66. When the piston is in the extreme rightward position shown in 
FIG. 2a, at which the right face of the piston abuts cavity surface 62, 
the piston will uncover a ring of circumferentially-spaced radial first 
vent openings, severally indicated at 68, but will cover another similar 
ring of circumferentially-spaced radial second vent openings, severally 
indicated at 69, spaced axially from the first ring. Conversely, when the 
piston is in the extreme leftward positon shown in FIG. 2b, at which the 
left face of the piston abuts cavity surface 61, the piston will cover the 
first vent openings and uncover the second vent openings. 
This embodiment is shown as having six electrically-operated valves 70, 
71,72,73,74,75 mounted on the body. The first and second valves 70,71 
receive the pressurized fluid from a suitable source (not shown), and may 
be selectively operated to admit fuel to first chamber 65. The third valve 
72 receives pressurized oxidizer from a suitable source (not shown), and 
may be selectively operated to admit oxidizer to the first chamber. When 
it is desired to move the piston rightwardly, valves 70,71, 72 are 
momentarily opened to admit minute quantities of fuel and oxidizer to 
chamber 65. The resulting hypergolic reaction between the fuel and 
oxidizer creates a pressure sufficient to drive the piston rightwardly. 
When such displacement of the piston uncovers vents 68, the products of 
this reaction are thereafter permitted to exhaust from the first chamber. 
Conversely, the fourth and fifth valves 73,74 receive pressurized fuel 
from a suitable source (not shown), and may be selectively operated to 
admit fuel to second chamber 66. The sixth valve 75 receives pressurized 
oxidizer from a suitable source (not shown), and may be selectively 
operated to admit oxidizer to second chamber 66. Thus, when it is desired 
to move the piston leftwardly, valves 73,74,75 are momentarily opened to 
admit minute quantities of fuel and oxidizer to chamber 66. Such mixture 
of the fuel and oxidizer will cause a hypergolic reaction in second 
chamber 66, and the products of this reaction will create a pressure 
sufficient to drive the piston leftwardly against body surface 61. When 
vent 69 has been uncovered, the reaction products will be allowed to 
exhaust from the second chamber. 
The rightward valve portion 59 is, in substance, a mirror image of the 
valve portion 11 of the first embodiment. Hence, the same reference 
numerals have been used to identify the corresponding elements and 
surfaces of this portion of the second embodiment, and a specific 
description thereof will be omitted. If desired, pressurized fuel may be 
supplied from conduit 18 to valves 70,71 via series-connected conduits 
76,78,79 and series-connected conduits 76,78,80, respectively; and 
supplied to valves 73,74 via series-connected conduits 76,81,82 and 
series-connected conduits 76,81,83, respectively. Similarly, pressurized 
oxidizer may be supplied from conduit 20 to valve 72 via series-connected 
conduits 84,85, and to valve 75 via series-connected conduits 84,86. 
In this second embodiment, the piston is coupled to valve members 25,26 by 
horizontally-elongated upper and lower rod assemblies 88,89, respectively. 
Each rod assembly has a leftward rod 90, a rightward rod 91, and a spring 
92 acting therebetween. 
Each of left rods 90 has its left marginal end portion sealingly and 
slidably mounted in a leftward horizontal hole 93 provided in the body, 
has an intermediate portion penetrating an aligned horizontal hole 94 
provided in the piston has a nextrightward portion sealingly and slidably 
mounted in another aligned horizontal hole 95 provided in the body, and 
has a radially-enlarged head adjacent its right end. This head 
accommodates a stepped recess, which extends leftwardly from its right end 
face, and telescopingly receives the left marginal end portion of right 
rod 91. This recess is shown as including left and right annular vertical 
abutment surface 96,98, respectively. Left rods 90 are suitably fixed to 
the piston for movement therewith. 
As previously noted, the left marginal end portions of right rods 91 are 
received in the associated left rod recesses. A washer-like member 99 is 
fixed to an intermediate portion of each right rod, and is arranged within 
the left rod recess. Each spring 92 is arranged to act between left rod 
abutment surface 96 and right rod abutment member 99. These coil springs 
are compressed and continuously urge right rods 91 to move rightwardly 
until abutment members 99 engage recess abutment surfaces 98, as shown in 
FIG. 1b. However, when the actuator portion is operated so as to displace 
the piston rightwardly relative to the body, the valve members 25,26 will 
engage their associated seats before piston 64 reaches the end of its 
stroke. Hence, springs 92 act as cushions to accommodate further rightward 
movement of the actuator piston after valve members 25,26 have seated. On 
the other hand, when it is desired to open the valve portion, abutment 
surfaces 98 will engage abutment washers 99, and thereafter cause the 
valve members to move leftwardly with the piston. 
As with the first embodiment, this second embodiment may be readily 
modified so as to use the products of a disassociation reaction between a 
suitable mono-propellant fuel and a catalyst, rather than the products of 
the hypergolic reaction previously described. To effect this, a suitable 
catalyst bed, such as shown in phantom and indicated at 97, may be placed 
in each of chambers 65,66. Oxidizer valves 72,75 would be unnecessary, and 
the suitable fuel could be admitted via one or both of valves 70,71 and/or 
73,74. Hence, upon operation of such valve(s), fuel admitted to the 
appropriate chamber would, upon contact with the catalyst, undergo a 
disassociation reaction, and the products thereof used to displace the 
piston. It should also be understood that the number and arrangement of 
the sensed solenoid valves is only illustrative, and may be readily 
changed or modified. 
Third Embodiment (FIGS. 3a-3b) 
A third embodiment of the improved actuator, generally indicated at 100 in 
FIGS. 3a-3b, is shown as schematically including a leftward actuator 
portion 101 and a rightward valve portion 102, both of which are provided 
within a horizontally-elongated common rectangular body 103. 
This body is shown as having a leftward relatively-large cylindrical 
cavity, which communicates through a narrow intermediate radial throat 
with a rightward relatively-small cylindrical valve cavity 104. Both of 
these cylindrical cavities are generated about vertical axes. Upper and 
lower vertical holes 105,106 are provided in the body and communicate with 
valve cavity 104 to provide inlet and utlet passageways, respectively. 
Inlet 105 communicates with a suitable source (not shown) of a serviced 
fluid, while outlet 106 communicates with a suitable device (not shown) 
consumptive of such fluid. A portion of the body about the upper end of 
outlet 106 is configured as a cylindrical collar, and terminates in an 
upwardly-facing annular horizontal seat 108. 
A diaphragm-like member, generally indicated at 109, is operatively 
arranged in the leftward large body cavity, and sealingly subdivides the 
same into an upper or first chamber 110 and a lower or second chamber 111. 
member 109 has a horizontal central disk-like solid element 112, and two 
vertically-spaced annular snap rings 113,114 positioned thereabout. The 
inner margins of these rings flexibly engage the cylindrical side surface 
of central element 112, while the outer margins of these rings are 
received in inwardly-facing annular recesses provided in the body. Upper 
and lower flexible membranes 115,116 are mounted on the upper and lower 
surfaces of member 109, and sealingly separate chambers 110,111. The snap 
rings 113,114, which somewhat resemble Belleville springs, impart a 
toggle-like snap action to central element 112. When snapped upwardly, as 
shown in FIG. 3a, member 109 moves toward surface 107 such that disk 
element 112 will close an upper or first vertical axial vent opening 118, 
which normally communicates with upper chamber 110. Conversely, when 
snapped downwardly, as shown in FIG. 3b, member 109 moves toward surface 
117 such that element 112 will close a lower or second vertical axial vent 
opening 119, which normally communicates with lower chamber 111. Thus, 
member 109 may be snapped from the position shown in FIG. 3a to the 
position shown in FIG. 3b, or vice versa, but is unstable in any other 
intermediate position. When member 109 is in the position shown in FIG. 
3a, upper vent opening 118 will be closed, but lower vent opening 119 will 
be opened. Conversely, when member 109 is in the position shown in FIG. 
3b, lower vent opening 119 will be closed, but upper vent opening 118 will 
be opened. 
A rod 120 has its leftward marginal end portion suitably secured to the 
underside of upper snap ring 113, has an intermediate portion penetrating 
an O-ring 121, which acts as a fulcrum, arranged in the narrow throad 
communicating the two cavities, and has its right marginal end portion 
arranged in valve cavity 104. Thus, the rod is mounted for pivotal 
movement about O-ring 121 in response to movement of upper ring 113. A 
resilient member 122 is mounted on the underside of the rod adjacent its 
rightward end, for pivotal movement toward and away from seat 108. When 
member 109 is snapped upwardly to the position shown in FIG. 3a, cushion 
122 will be moved downwardly and will sealingly engage seat 108, thereby 
blocking flow from the inlet to the outlet. However, when member 109 is 
snapped downwardly to the position shown in FIG. 3b, cushion 122 will be 
moved upwardly off seat 108, thereby permitting flow from the inlet to the 
outlet. 
Four electrically-operated valves 123,124,125,126 are mounted on the body. 
The first valve 123 communicates with a pressurized source (not shown) of 
fuel via series-connected conduits 128,129. The second valve 124 
communicates with a pressurized source (not shown) of oxidizer via 
series-connected conduits 130,131. The third valve 125 communicates with 
the fuel source via series-connected conduits 129, 132. The fourth valve 
126 communicates with the oxidizer source via series-connected conduits 
131,133. All four valves may be simple normally-closed solenoid-type 
devices, which may be selectively opened by application of a suitable 
electrical signal. 
When the member is in its upward position, as shown in FIG. 3a, valves 
123,124 may be simultaneously opened to admit minute quantities of fuel 
and oxidizer to upper chamber 110, while disk 112 closes vent 118. When 
mixed together, the fuel and oxidizer undergo a hypergolic reaction, and 
the products of this reaction are initially confined to the upper chamber. 
This reaction creates a pressure which quickly moves element 112 
downwardly, thereby snapping member 109 to the alternative stable position 
shown in FIG. 3b. Thus, whereas the reaction products were initially 
confined to the first chamber, such downward movement of element 112 opens 
upper vent 118, thereby permitting the first chamber to exhaust. 
When the member is in the position shown in FIG. 3b, lower vent 119 is 
closed. Valves 125,126 may then be selectively opened to admit fuel and 
oxidizer to lower chamber 111. When this occurs, the resulting hypergolic 
reaction in chamber 111 quickly snaps member 109 upwardly to the stable 
position shown in FIG. 3a, and thereafter permits the reaction products to 
exhaust from the second chamber through now-opened vent 119. 
In this manner, the various valves may be operated in cooperative pairs to 
selectively move member 109 upwardly and downwardly between the stable 
hardover positions, shown in FIGS. 3a and 3b. Such movement of member 109 
will produce corresponding movement of cushion 122, thereby selectively 
opening and closing the valve. 
The valve assembly shown in FIGS. 3a and 3b may be readily modified to use 
the products of a disassociation reaction between a mono-propellant fluid 
fuel and a catalyst, if so desired. To do this, a suitable catalyst bed, 
such as shown in phantom and indicated at 134, would be positioned in the 
upper and lower chambers. A suitable mono-propellant fluid fuel could then 
be selectively admitted to either chamber. Upon contact with the catalyst 
in such chamber, the injected fuel would undergo a disassociation 
reaction, and the products thereof would create a pressure sufficient to 
displace member 109 to its other position. 
Moreover, the invention may be structurally simplified by providing a 
single fuel inlet valve and a single fuel outlet valve, with an 
appropriate diverter valve between the member and enclosure for 
selectively diverting the reaction products into the 
chamber-to-be-expanded. 
Fourth Embodiment (FIGS. 4a-4b) 
A fourth embodiment of the improved actuator, generlaly indicated at 135 in 
FIGS. 4a and 4b, is schematically shown as including a leftward valve 
portion 136 and a rightward actuator portion 138. 
Valve portion 136 is substantially the same as the valve portion 11 of the 
first embodiment shown in FIGS. 1a and 1b. Hence, the same reference 
numerals have been again used in FIGS. 4a and 4b to identify like 
structure previously described, with the following additional description 
being directed to those few features by which valve portion 136 differs. 
Specifically, in this fourth embodiment, the rightward marginal end 
portion of valve portion body 13 is shown as further including a 
rightwardlyfacing annular vertical surface 139 extending radially inwardly 
from the upper and lower planar surfaces thereof, an outwardly-facing 
horizontal cylindrical surface 140 extending rightwardly therefrom, and 
terminating in a rightwardmost circular vertical right end face 141. An 
annular slot, generally indicated at 142, extends radially into the valve 
portion body from surface 140. The respective horizontal holes in which 
rods 29,30 are slidably mounted, are shown as extending between the upper 
and lower chambers 14,15, and the right end face 141, so as to intersect 
intermediate slot 142. O-rings 143,144 seal the sliding joint between each 
actuator rod and the portions of the valve body on either side of slot 
142. As shown in FIGS. 4a and 4b, the right marginal end portions of rods 
29,30 extend horizontally beyond valve portion body right end face 141, 
and are suitably connected to the piston. 
The actuator portion 138 is shown as broadly including a body 145 and a 
piston 146 slidably mounted thereon. The actuator body is shown as being a 
leftwardly-facing horizontally-elongated cup-shaped member, and as having 
integrally-formed internal and external axial post portions 148,148, 
respectively, extending leftwardly and rightwardly from the bottom of body 
145. More particularly, the actuator body has an annular vertical left end 
face 150 suitably secured to the outer margin of valve body right end face 
141, has a substantially circular vertical right end face 151, and has an 
outer surface which sequentially includes an outwardly-facing horizontal 
cylindrical surface 152 extending rightwardly from left end face 150, a 
rightwardly-facing annular vertical surface 153, and an outwardly-facing 
horizontal cylindrical surface 154 continuing rightwardly therefrom to 
join right end face 151. Diametrically-opposite portions of the 
rightwardly-extending external post portion 149 are shown as being 
appropriately bevelled to accommodate mounting of a pair of 
electrically-operated valves 155,156. The inner surface of the actuator 
body sequentially includes an inwardly-facing horizontal cylindrical 
surface 158 extending rightwardly from left end face 150, a 
leftwardly-facing annular vertical surface 159, an outwardly-facing 
horizontal cylindrical surface 160 extending leftwardly therefrom and 
terminating in a leftwardmost vertical circular surface 161. Surfaces 
160,161 partially define the leftwardly-extending internal post portion 
148, while surfaces 154,151 partially define the rightwardly-extending 
external post portion 149. A vertical hole 162 extends diametrically 
through the internal post portion. Hole 162 intersects with a 
horizontally-elongated chamber, generally indicated at 163, within the two 
post portions, which chamber terminates in a rightwardmost mixing chamber 
portion 164. Chamber portion 164 is arranged to receive fluid supplied by 
valves 155,156. 
Piston 146 is operatively mounted within the actuator body for leftward and 
rightward horizontal sliding movement relative thereto. Specifically, the 
piston has a circular vertical left end face 165, an annular vertical 
right end face 166, and an outwardly-facing horizontal cylindrical surface 
168 extending therebetween and slidably engaging body inner surface 158. A 
large diameter axial blind recess is shown as extending leftwardly into 
the piston from its right end face 166. Specifically, this recess is 
bounded by an inwardly-facing horizontal cylindrical surface 169 extending 
leftwardly from right end face 166, and a rightwardly-facing vertical 
circular surface 170. Piston recess surface 169 slidably engages internal 
post outer surface 160. Thus, the piston is operatively mounted on the 
actuator body for leftward and rightward horizontal sliding motion between 
valve portion body right end face 141 and actuator body portion surface 
159. As previously indicated, the right marginal end portions of rods 
29,30 are fixed or otherwise secured to the piston for movement therewith. 
The piston is further shown as being provided with two L-shaped 
passageways. A first of these passageways, generally indicated at 171, 
communicates piston recess surface 169 with piston right end face 166. The 
second of these passageways, generally indicated at 172, communicates 
piston recess surface 169 with piston left end face 172. These passageways 
are so configured and dimensioned, as shown in FIGS. 4a and 4b, that when 
the piston is in its extreme leftward position (as shown in FIG. 4a), 
passageway 172 communicates with internal post hole 162, while passageway 
171 is separated from this hole. On the other hand, when piston 146 is in 
its extreme rightward position (as shown in FIG. 4b), passageway 171 
communicates with internal post portion hole 162, while passageway 172 
does not. 
Conduit 173 supplies fluid fuel from a source thereof to valve portion 
inlet opening 16. Conduit 174 communicates conduit 173 with valve 155. 
Conversely, conduit 175 provides fluid oxidizer from a suitable source 
thereof to valve portion inlet opening 19. Conduit 176 communicates 
conduit 175 with valve 156. Each of electrically-operated valves 155,156 
is normally-closed. However, these valves may be selectively operated so 
as to open simultaneously, and to admit minute quantities of fuel and 
oxidizer to mixing chamber portion 164. 
When piston 146 is in its extreme leftward position such that piston left 
face 165 abuts valve portion right end face 141 (as shown in FIG. 4a), 
valve members 25,26 engage their respective seats 23,24 to prevent flow 
through the valve. If valves 155,156 are now opened to admit minute 
quantities of fuel and oxidizer to mixing chamber 154, such fluids will 
undergo a hypergolic reaction in chamber 163 and mixing chamber 164, and 
the products of this reaction will pass through piston passageway 172 to 
drive piston 146 rightwardly to the position shown in FIG. 4b. As this 
occurs, any fluid in piston right end chamber 178 is permitted to exhaust 
through a plurality of vent openings, severally indicated at 179. At the 
same time, other vent openings 180 are covered and blocked by the piston, 
until it passses by. When the actuator piston moves rightwardly from the 
position shown in FIG. 4a to the position shown in FIG. 4b, the valve 
members 25,26 will be moved rightwardly off their respective seats to 
permit flows of fuel and oxidizer through the valve, such as to hypergolic 
rocket engine. 
When the piston is in its extreme rightward position such that piston right 
end face 166 abuts actuator body surface 159 (as shown in FIG. 4b), valves 
155 and 156 may be momentarily opened to again admit minute quantities of 
fuel to chamber 163. However, when the piston is in this rightward 
position, piston passageway 172 is blocked, but piston passageway 171 
communicates with internal post portion hole 162. Hence, such admitted 
quantities of fuel and oxidizer will undergo a hypergolic reaction, and 
the gaseous products thereof may pass through hole 162 and passageway 171 
to drive the piston leftwardly from the position shown in FIG. 4b to the 
alternative position shown in FIG. 4a, thereby moving valve members 25,26 
to engage their respective seats and preventing further flow through the 
valve. At the same time, any fluid in piston left end chamber 181 will be 
permitted to exhaust through vent openings 180. Thus, in this second 
embodiment, only two electrically-operated valves, namely valves 155,156 
are used to operatively control the displacement of the actuator piston, 
and, concomitantly, the opening and closing of the valve. 
As with the first three embodiments, this fourth embodiment may be readily 
modified so as to use the products of a disassociation reaction between a 
suitable mono-propellant fuel and a catalyst, rather than the products of 
a hypergolic reaction just described. To accomplish this alternative, a 
suitable catalyst bed, such as shown in phantom and indicated at 182 may 
be placed in mixing chamber 164. Valve 156 would then be unnecessary, and 
the electrically-operated fuel supply valve 155 could be selectively 
operated to admit such mono-propellant fuel to chamber 164, within which a 
disassociation reaction would occur, and the products thereof used to 
displace the piston. 
Therefore, while four embodiments of the invention have been shown and 
described, and several modifications thereof have been shown and 
described, and several modifications thereof discussed, persons skilled in 
this art will readily appreciate that various additional changes and 
modifications may be made without departing from the spirit of the 
invention, as defined and differentiated by the following claims.