Two-stage cold gas propeller

Abstract

A cold gas mover equipped with a two-stage solenoid valve is provided herein. Pressurized gas from the inlet flows into the rear side of the piston (134), keeping the piston closed. The pressure is maintained by a check ball held by a solenoid valve armature. When the solenoid valve is energized, the armature moves, displaces the check ball, and releases the pressure that keeps the piston closed. The piston moves away from its seat, enabling the pressurized gas to flow to the outlet, thereby creating thrust. When the electromagnetic valve coil is powered off, the check ball is forced to abut against the seat of the check ball, pressure on the rear side of the piston is prevented from escaping, and the check ball is pressurized to the air inlet pressure again. This results in a force imbalance, moving the piston to close the valve, and stopping the thrust output. Different nozzles can be used for different thrust curves, and the electromagnetic valve does not need to be replaced.

Description

Technical Field

[0001] The present invention relates generally to cold gas thrusters and, more particularly, to a solenoid valve actuation mechanism for a cold gas thruster. Background Art

[0002] Cold gas, monopropellant and bipropellant thrusters are used in aerospace applications to control the attitude, position and orientation of a variety of mechanical devices such as satellites, missiles and other spacecraft. The solenoid valves used on these thrusters are usually electromechanical devices that are used to open and close the fluid medium used to generate the propulsion force. Cold gas thrusters are specifically used to open and close high-pressure gases that are expanded through a supersonic nozzle without combustion. The typical fluid commonly used in cold gas thrusters is high-pressure gaseous nitrogen.

[0003] Because such thrusters are often used for fine position control adjustments required to maintain stable positioning, the timing of the application and termination of these thrusts must occur within tight tolerances. Unfortunately, the solenoid valves used in such thrusters have an inherent lag in the actuation and termination of the valve, and this lag time can vary. This lag is caused by magnetic flux generation and decay times, mechanical inertia of the armature, spring load differences, pressure differentials acting on the valve components, etc. In practice, the higher the propellant pressure that the solenoid must control, the larger the solenoid must be, which tends to increase these lag parameters.

[0004] Therefore, there is a need for a cold gas thruster whose solenoid valve actuation mechanism can minimize the start and end times, reduce the time difference between such start lag and end lag time, achieve actuation of various thrust levels, and reduce the overall size and weight of the actuation control device. Embodiments of the present invention provide such a cold gas thruster and its solenoid valve actuation mechanism. These and other advantages of the present invention, as well as other innovative features, will be apparent from the description of the invention herein. Summary of the invention

[0005] In view of the above, embodiments of the present invention provide a novel and improved cold gas thruster having a solenoid valve actuation mechanism that overcomes at least one problem existing in the prior art. More specifically, embodiments of the present invention provide a novel and improved cold gas thruster having a solenoid valve actuation mechanism that at least reduces the start and end time, reduces the time difference between such start lag time and end lag time, achieves actuation of various thrust levels, and / or reduces the overall size and / or weight of the actuation control device.

[0006] In one embodiment, the two-stage solenoid valve actuation mechanism has one or more unique features, including low power required for startup, reduced required solenoid valve force output compared to a single-stage actuator (in one embodiment this is due to the smaller pilot orifice size and ceramic ball), fast response, and very high force margin.

[0007] In one embodiment, a snap-on solenoid valve with a short first stage armature stroke is employed. In such an embodiment, very fast second stage motion results due to the high force margin and the short stroke achieved thereby. Certain embodiments provide high flow outputs and have the flexibility to accommodate a variety of second stage valves for both high and low flow requirements.

[0008] In an embodiment of the present invention, the solenoid valve actuator has low leakage due to the high sealing force on the second stage piston. This allows the use of metal seals, which provide high durability. Low leakage is also a result of the first stage ceramic balls used in one embodiment, which have very tight ball bearing tolerances. This ensures extremely low leakage between the ball and the metal seat when the first stage is closed.

[0009] In certain embodiments, the cold gas thruster of the present invention uses a non-welded threaded design. This threaded interface of the first stage actuator and nozzle eliminates welding and identification and inspection costs. In addition, in these embodiments, the threaded interface allows for disassembly and troubleshooting during final assembly and testing, thereby further reducing costs.

[0010] In an embodiment, a first-stage design with threaded and bolted connections allows the first-stage solenoid valve to be easily adapted to other solenoid valve applications. This threaded design allows the use of second-stage poppet valves of different lengths to achieve a variety of strokes to meet the flow or thrust levels required by different applications.

[0011] In certain embodiments, a removable / replaceable supersonic nozzle is provided. This allows the same actuator and overall thruster design to be used to achieve a variety of nozzle sizes for different thrust outputs and desired expansion configurations. It also allows the same design to be used with different styles of nozzle diffusers (e.g., conical, bell-shaped, etc.).

[0012] In an embodiment of the invention, the first stage actuator uses a guided snap-fit ​​armature. This provides a high force margin solenoid valve with improved high vibration performance. In such an embodiment, the total height of the armature return spring seat / cup sets the closed armature air gap. The reset pole uses a simple disc design, and by setting this component as an optional component (i.e., different thicknesses), the air gap created by the armature return spring seat / cup can be matched in final assembly. In an embodiment, a simple bobbin wound coil is installed into the solenoid valve housing.

[0013] In certain embodiments, an integrated inlet fitting is provided in or defined by the main housing. Such embodiments reduce the number of components and improve reliability. This also improves high pressure structural performance by eliminating a separate fitting interface.

[0014] By combining more than one of the above features, embodiments of the present invention provide a two-stage cold gas thruster that can be turned on and off with a fast response time and can generate thrust using high-pressure nitrogen expanded through a supersonic nozzle. These embodiments require only low power to start, but provide fast response, have low mass and small form factor, high flow output, low internal leakage, and can generate a variety of thrust outputs simply by replacing the nozzle (without replacing the solenoid valve actuator). Certain embodiments are suitable for existing and future aerospace applications, such as in missiles, rockets, satellites, etc. Switching between various thrust outputs only requires replacing one component, namely the nozzle. This platform approach and reuse reduces production costs.

[0015] In a preferred embodiment of the present invention, a cold gas thruster includes a housing having an integrated inlet, a nozzle connection, and an actuator connection formed therefrom. The thruster also includes a nozzle body that is removably connected to the housing at the nozzle connection; and an actuator that is removably connected to the housing at the actuator connection. The actuator has a first-stage solenoid valve that is configured to position a check ball on a discharge hole of a piston guide; and a second-stage piston that is slidably received in the nozzle for opening and closing a thrust hole in the nozzle between the inlet and the thrust outlet. The piston includes a hole that is configured to connect pressurized gas from the inlet to the rear side of the piston between the piston and the piston guide so that the piston is held closed against the thrust hole when the check ball is held against the discharge hole by the armature of the first-stage solenoid valve. In addition, energizing the first-stage solenoid valve causes the armature to move, thereby causing the check ball to leave the discharge hole, exhausting the pressurized gas that holds the piston closed, thereby causing the piston to open and allow the pressurized gas to flow to the thrust outlet.

[0016] In another embodiment, when the first stage solenoid valve is de-energized, it causes the armature to position the check ball against the exhaust hole to prevent pressure on the rear side of the piston from escaping, thereby moving the piston to close the thrust hole. Preferably, the housing defines an exhaust passage configured to exhaust pressurized gas on the rear side of the piston in a direction perpendicular to the longitudinal axis of the nozzle when the check ball leaves the exhaust hole. In one embodiment, the exhaust passage includes a plurality of exhaust passages evenly distributed around the periphery of the housing.

[0017] In an embodiment, the first stage solenoid valve is a snap-on solenoid valve, which preferably includes an armature spring configured to force the armature to seat the check ball against the discharge hole. In an embodiment, the armature spring is located in a ball guide between the piston guide and the armature. Further, in an embodiment, the armature is guided in an alignment bushing to seat the check ball against the discharge hole. In yet another embodiment, the sealing end of the second stage piston is formed as a rounded contour surface to mate with a conical seat in the nozzle, forming a cone-on-sphere arrangement, wherein a "ball" or rounded portion is machined on a piston slidably received in the nozzle, forming a low leakage metal-to-metal seal between the inlet and the thrust outlet.

[0018] In an embodiment of the present invention, a two-stage actuator for a cold gas thruster has a housing having an integrated inlet, a nozzle connection and an actuator connection formed thereby, and a nozzle body that is removably connected to the housing at the nozzle connection. The two-stage actuator includes a solenoid valve housing that is configured to be removably connected to the housing at the actuator connection of the housing; a first-stage solenoid valve that is configured to position a check ball on the discharge hole of a piston guide; and a second-stage piston that is slidably received in the nozzle for opening and closing a thrust hole in the nozzle located between the inlet and the thrust outlet. Preferably, the piston includes a hole that is configured to connect pressurized gas from the inlet to the rear side of the piston between the piston and the piston guide so that the piston is held closed against the thrust hole when the check ball is held against the discharge hole by the armature of the first-stage solenoid valve. Additionally, the first stage solenoid valve is energized to move the armature, thereby moving the check ball away from the exhaust port to exhaust the pressurized gas holding the piston closed, thereby opening the piston and allowing the pressurized gas to flow to the thrust outlet.

[0019] In a preferred embodiment, de-energizing the first stage solenoid valve causes the armature to position the check ball against the discharge hole to prevent pressure from the rear side of the piston from escaping, thereby moving the piston to close the thrust hole. Preferably, the first stage solenoid valve is a snap-on solenoid valve and includes an armature spring configured to force the armature to position the check ball against the discharge hole.

[0020] In a further embodiment, the check ball is located in a ball guide between the piston guide and the armature. The armature is guided in an alignment bushing to seat the check ball against the discharge orifice. Preferably, the sealing end of the second stage piston is formed with a rounded contoured surface to mate with a conical seat in the nozzle, forming a ball-cone fit, wherein a "ball" or rounded portion is machined onto the piston slidably received in the nozzle, forming a low leakage metal-to-metal seal between the inlet and thrust outlet, which seal is able to tolerate small degrees of misalignment and / or tilting of the piston to maintain sealing.

[0021] Other aspects, objects and advantages of the present invention will become more apparent from the following detailed description when read in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate several aspects of the present invention and, together with the description, serve to explain the principles of the present invention. In the drawings:

[0023] Figure 1 is a cross-sectional view of an embodiment of a two-stage cold gas thruster constructed in accordance with the teachings of the present invention;

[0024] Figure 2 yes Figure 1 A cross-sectional view of an embodiment of a two-stage cold gas thruster employing an alternative filter placement constructed in accordance with the teachings of the present invention;

[0025] Figure 3 is a cross-sectional view of another embodiment of a two-stage cold gas thruster constructed in accordance with the teachings of the present invention;

[0026] Figure 4 yes Figure 3 Cross-sectional view of an embodiment of a two-stage cold gas thruster employing an alternative filter placement constructed in accordance with the teachings of the present invention.

[0027] While the invention will be described in conjunction with certain preferred embodiments, it is not intended to be limited to those embodiments. On the contrary, the intention is to cover all alternatives, modifications and equivalents within the spirit and scope of the invention as defined by the appended claims. DETAILED DESCRIPTION

[0028] Turning now to the drawings, there are illustrated embodiments of the present invention which can provide cold gas thrust for numerous aviation and aerospace applications. However, while the illustrated embodiments are suitable for such applications, other embodiments of the present invention are not so limited, and such description should be viewed as illustrative rather than limiting. Indeed, the two-stage solenoid valve actuator used in embodiments of the present invention can also be used in other applications requiring low power, fast startup and termination, and other advantages described herein.

[0029] refer to Figure 1-Figure 4, respectively, illustrate cross-sections of embodiments of two-stage cold gas thrusters 100, 100', 200, 200' constructed in accordance with the present invention. In each such embodiment, pressurized gas (e.g., nitrogen) enters the inlet 128, 228 of the second stage valve 104, 204, passes through the filter 120, 220 surrounding the piston 134, 234 or through the filter 120', 220' located in the inlet 128, around the outer diameter (OD) of the piston 134, 234, and fills the cavity 136, 236 on the back side of the piston 134, 234 through the control hole 118, 218. When the solenoid valve coil 114, 214 of the first stage solenoid valve 102, 202 is not energized, the resulting force imbalance pushes the piston 134, 234 into the second stage valve seat 124, 224, forming a low leakage metal-to-metal seal between the inlet 128, 228 and the outlet 130, 230.

[0030] Although Figure 1 and Figure 2 The embodiment of the present invention uses a lift valve piston 134 and a secondary valve seat 124, but Figure 2 The piston 234 and the secondary valve seat 224 in the embodiment of the present invention are configured as a "ball-cone fit" structure, wherein a "ball" or rounded portion is machined on the piston 234. This valve seat structure has been proven to be an excellent, low leakage metal-to-metal seal.

[0031] The pressure on the back side of the piston 134, 234 is maintained in the cavity 136, 236 by the armature 110, 210 of the first stage solenoid valve 102, 202, which pushes the valve member against the first stage valve seat. Figure 1 The embodiment of the present invention uses a poppet-type valve member 132 to seal the first stage valve seat 126, but Figure 2 The embodiment of the present invention employs a check ball 232 which is urged against the first stage valve seat 226. In each embodiment, the force to close the first stage solenoid valve 102, 202 is provided by the armature spring 112, 212.

[0032] When the solenoid valve coil 114, 214 is energized, the armature 110, 210 overcomes the force of the armature spring 112, 212 and moves toward the solenoid valve assembly 108, 208 until the armature stop 138, 238 hits the solenoid valve housing pole 140, 240. The armature stop 138, 238 sets a closed air gap. The movement of the armature 110, 210 causes Figure 1 Valve component 132 or Figure 2The check ball 232 in the second stage valve 104, 204 moves away from the first stage valve seat 126, 226 to exhaust the pressure on the rear side 136, 236 of the piston 134, 234 of the second stage valve 104, 204. This changes the direction of the force imbalance on the piston 134, 234, causing it to move away from the second stage valve seat 124, 234 and stop against the piston guide 142, 242.

[0033] In this state, the flow from the inlet 128, 228 through the control hole 118, 218 remains continuous, and the size of the control hole 118, 218 sets the maximum exhaust flow. The exhaust flow is then released into the surrounding environment through a plurality of first-stage exhaust holes 116, 216. In an embodiment, three exhaust holes 116, 216 are provided, which are radially distributed around the main casing, pointed vertically relative to the centerline of the thruster 100, 100', 200, 200', and circumferentially spaced at 120° to provide a net neutral exhaust thrust. More or fewer exhaust holes 116, 216 may also be provided and spaced accordingly to provide such a neutral exhaust thrust. The airflow from the inlet 128, 228 may then pass through the supersonic nozzle throat 122, 222 and be discharged from the outlet 130, 230, generating thrust along the centerline of the nozzle 106, 206.

[0034] When the solenoid valve coils 114 and 214 are de-energized, Figure 1 and Figure 2 Valve component 132 or Figure 2 and Figure 3 The check ball 232 in the second stage valve 104, 204 is pushed by the armature spring 112, 212 through the armature 110, 210 and forced against the first stage valve seat 126, 226. This prevents the pressure on the back side 236 of the piston 134, 234 of the second stage valve 104, 204 from escaping, allowing it to be re-pressurized to the inlet pressure. This creates an imbalance of the force required to move the piston 134, 234 toward and contact the valve seat 124, 224, thereby closing the second stage valve 104, 204.

[0035] Two-stage actuation allows for the use of smaller, lighter, and faster electromagnetic solenoids 108, 208 to open and close the main (second stage 104, 204) pistons 134, 234, regardless of the thrust requirements of the thruster 100, 100', 200, 200'. The piston / valve seat interfaces of both the poppet valve type 124 and the ball-cone fit type 224 are very durable and have excellent sealing performance, and the design of the two-stage thruster 100, 100', 200, 200' actuator ensures that the thruster's pressurized gas maintains the seal with appropriate force. In fact, because the illustrated embodiment uses a threaded nozzle 106, 206, a variety of nozzle designs and thrust outputs can be achieved by replacing only one component (i.e., the nozzle 106, 206).

[0036] All references, including publications, patent applications, and patents, cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein.

[0037] "A, an", "the" and similar references used in describing the present invention (particularly in the context of the following claims) should be interpreted as covering the singular and the plural, unless otherwise indicated herein or the context clearly contradicts. The terms "include", "have" and "include" should be interpreted as open terms (i.e., meaning "including but not limited to"), unless otherwise indicated. The enumeration of numerical ranges herein is intended only as a shorthand method to refer to each individual value falling within the range individually, unless otherwise indicated herein, and each individual value is incorporated into this specification as if it were individually enumerated herein. All methods described herein can be performed in any suitable order, unless otherwise indicated herein or the context clearly contradicts. Any and all examples or exemplary language (e.g., "for example") provided herein are intended only to better illustrate the present invention, and unless otherwise claimed, will not limit the scope of the present invention. Any language in this specification should not be interpreted as indicating that any unclaimed element is essential for implementing the present invention.

[0038] Preferred embodiments of the present invention are described herein, including the best mode of implementing the present invention known to the inventors. After reading the above description, variations of these preferred embodiments may be apparent to those of ordinary skill in the art. The inventors expect that the skilled person will adopt such variations as appropriate, and the inventors intend to implement the present invention in a manner different from that specifically described herein. Therefore, the present invention includes all modifications and equivalents of the subject matter described in the appended claims permitted by applicable law. In addition, unless otherwise specified herein or clearly contradicted by the context, the present invention covers any combination of the above elements in all possible variations. For example, a combination of different valve components of the first-stage valve and the second-stage valve can be envisioned, including closing with a check ball against the first-stage valve seat while closing with a lift valve component against the second-stage valve seat, and closing with a valve component against the first-stage valve seat while the second-stage valve adopts a ball-cone fitting structure, and so on.

Claims

1. A cold gas thruster comprising: a housing having an integrated inlet, nozzle connection, and actuator connection formed therefrom; a nozzle body removably connected to the housing at the nozzle connector; as well as an actuator detachably connected to the housing at the actuator connection of the housing, the actuator having a first-stage solenoid valve configured to open and close a discharge hole of a piston guide, and a second-stage piston slidably received in the nozzle to open and close a thrust hole in the nozzle between the inlet and a thrust outlet; wherein the piston includes a hole configured to connect pressurized gas from the inlet to the rear side of the piston between the piston and the piston guide so as to hold the piston closed against the thrust hole when the exhaust hole is closed by the armature of the first stage solenoid valve; and The first-stage solenoid valve is energized to move the armature away from the exhaust hole, thereby opening the piston, exhausting the pressurized gas that keeps the piston closed, and allowing the pressurized gas to flow to the thrust outlet.

2. The cold gas thruster according to claim 1, wherein de-energizing the first-stage solenoid valve causes the armature to close the exhaust hole to prevent the pressure on the rear side of the piston from escaping, thereby moving the piston to close the thrust hole.

3. The cold gas thruster of claim 1 , wherein the housing defines an exhaust passage therein, the exhaust passage being configured to discharge the pressurized gas at the rear side of the piston in a direction perpendicular to the longitudinal axis of the nozzle when the exhaust hole is opened.

4. The cold gas thruster of claim 3, wherein the exhaust passage comprises a plurality of exhaust passages evenly distributed around the periphery of the housing.

5. The cold gas thruster of claim 1, wherein the first stage solenoid valve is a snap-on solenoid valve.

6. The cold gas thruster of claim 5, wherein the first stage solenoid valve comprises an armature spring configured to force the armature to close the exhaust orifice.

7. The cold gas thruster of claim 1, wherein when the solenoid valve coil is de-energized, the armature positions the check ball against the first stage valve seat to close the exhaust orifice.

8. The cold gas thruster of claim 7, wherein when the solenoid valve coil is energized, movement of the armature away from the exhaust orifice causes the check ball to leave the first stage valve seat to open the exhaust orifice.

9. A cold gas thruster according to claim 1, wherein the sealing end of the second stage piston is formed as a rounded contour surface to mate with a conical seat in the nozzle to form a ball-cone fit structure, wherein a "ball" or rounded portion is machined on the piston slidably received in the nozzle to form a low leakage metal-to-metal seal between the inlet and thrust outlet.

10. The cold gas thruster of claim 1 further comprising a filter surrounding the piston.

11. The cold gas thruster of claim 1 further comprising a filter located within the integrated inlet.

12. A two-stage actuator for a cold gas thruster having a housing with an integrated inlet, nozzle connection and actuator connection formed thereby, and a nozzle body removably connected to the housing at the nozzle connection, the two-stage actuator comprising: a solenoid valve housing configured to be removably connected to the housing at the actuator connection of the housing; a first stage solenoid valve configured to position the check ball over the discharge hole of the piston guide; as well as a second stage piston slidably received in the nozzle to open and close a thrust hole in the nozzle between the inlet and the thrust outlet; wherein the piston includes a hole configured to connect pressurized gas from the inlet to the rear side of the piston between the piston and the piston guide so as to hold the piston closed against the thrust hole when the check ball is held against the exhaust hole by the armature of the first stage solenoid valve; and The first-stage solenoid valve is energized to move the armature, causing the check ball to move away from the discharge hole to discharge the pressurized gas that keeps the piston closed, thereby opening the piston and allowing the pressurized gas to flow to the thrust outlet.

13. The two-stage actuator for a cold gas thruster according to claim 12, wherein de-energizing the first stage solenoid valve causes the armature to position the check ball against the exhaust hole to prevent pressure on the rear side of the piston from escaping, thereby moving the piston to close the thrust hole.

14. The two-stage actuator for a cold gas thruster according to claim 12, wherein the first stage solenoid valve is a snap-on solenoid valve.

15. The two-stage actuator for a cold gas thruster of claim 14, wherein the first stage solenoid valve includes an armature spring configured to urge the armature to seat the check ball against the exhaust orifice.

16. The two-stage actuator for a cold gas thruster according to claim 12, wherein the check ball is located in a ball guide between the piston guide and the armature.

17. The two-stage actuator for a cold gas thruster according to claim 12, wherein the armature is guided in an alignment bushing to seat the check ball against the discharge hole.

18. A two-stage actuator for a cold gas thruster according to claim 12, wherein the sealing end of the second stage piston is formed as a rounded contour surface to mate with a conical seat in the nozzle to form a ball-cone fit structure, wherein a "ball" or rounded portion is machined on the piston slidably received in the nozzle to form a low leakage metal-to-metal seal between the inlet and thrust outlet.

19. The cold gas thruster of claim 12, further comprising a filter surrounding the piston.

20. The cold gas thruster of claim 12, further comprising a filter located within the integrated inlet.

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