Propulsion device, rocket, artificial satellite, and space probe

Abstract

This propulsion device generates a propulsive force by a combustion reaction, and includes: a combustion chamber, and a metal fuel supply device. The combustion chamber forms a combustion space inside of which it is possible to generate a combustion reaction. The metal fuel supply device is configured to supply a metal fuel to the combustion space. The supplied metal fuel is configured to extend in the combustion space, cause a combustion reaction, and vibrate during the combustion reaction as a result of theoperation of at least a part of the propulsion device.

Description

Propulsion devices, rockets, satellites and space probes

[0001] The present invention relates to thrusters, rockets, satellites and space probes.

[0002] Engines are essential for spacecraft, such as artificial satellites and space probes, to obtain thrust and move forward. In order for a spacecraft to obtain thrust (to propel itself), some kind of substance (called a propellant) must be released outside the spacecraft, and this role is played by spacecraft engines.

[0003] Spacecraft engines are classified by the type of energy they use to release. Those that use chemical reactions are called chemical propulsion rockets, and those that use electricity are called electric propulsion rockets. The former are used when a large amount of energy (large thrust) is required in a short period of time, while the latter are used when acceleration with a small amount of propellant is required even for a long period of time.

[0004] T. F. Miller and D. Herr, 40th Joint Propulsion Conference, AIAA2004-4037, 2004. L. Huang, et al. , Chinese Physics B, 24(9), pp. 094702-1-8, 2015.

[0005] However, there is still room for improvement in the above-mentioned known techniques.

[0006] In view of the above circumstances, the present invention provides a novel technique.

[0007] According to one aspect of the present invention, there is provided a propulsion device that generates thrust through a combustion reaction, the propulsion device comprising: a combustion chamber; and a metal fuel supply device, wherein the combustion chamber defines a combustion space within which a combustion reaction can occur; the metal fuel supply device is configured to supply metal fuel to the combustion space; the supplied metal fuel extends in the combustion space, causes a combustion reaction, and is configured to vibrate during the combustion reaction as a result of operation of at least a portion of the propulsion device.

[0008] According to this aspect, it is possible to provide a technology for atomizing condensable combustion products produced by a combustion reaction while using safe fuel and oxidizer.

[0009] FIG. 1B is a diagram showing an example of the overall configuration of a moving body 1. FIG. 1B is a cross-sectional view of the propulsion device 100 as viewed from the left side in the state shown in the A-A cross section shown in FIG. 1B, showing another example of the propulsion device 100 shown in FIG. 2 ... 9A is a cross-sectional view of the propulsion device 100 as viewed from the left side in the state shown in cross section A-A in FIG. 1B, showing another example of the propulsion device 100 shown in FIG. 9A is a graph showing an example of the feed speed V2 when the metal fuel 2 is supplied at a constant speed, and FIG. 9B is a graph showing an example of the feed speed V2 when the metal fuel 2 is supplied while accelerating and decelerating.

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the accompanying drawings. Various features shown in the following embodiments can be combined with each other.

[0011] Incidentally, a program for realizing the software appearing in one embodiment may be provided as a non-transitory computer-readable recording medium, or may be provided so as to be downloadable from an external server, or may be provided so that the program is started on an external computer and its functions are realized on a client terminal (so-called cloud computing).

[0012] Furthermore, various information processing according to an embodiment may realize input and output corresponding to the input. Here, the form of information referenced in such information processing (hereinafter referred to as reference information) is not limited as long as an output is obtained as a result of the input. The reference information may be, for example, rule-based information such as a database, a lookup table, or a predetermined function (including a determination formula such as a regression formula constructed using a statistical method), a trained model that has previously learned the correlation between input and output, or a generative AI such as a large-scale language model or a visual language model that can output a desired result by inputting a prompt.

[0013] In one embodiment, the term "unit" may include, for example, a combination of hardware resources implemented by a circuit in the broad sense and software information processing that can be specifically realized by these hardware resources. In one embodiment, various information is handled, and this information is represented, for example, by physical values ​​of signal values ​​representing voltage or current, high or low signal values ​​as a binary bit set consisting of 0 or 1, or quantum superposition (so-called quantum bits), and communication and calculations can be performed on the circuit in the broad sense.

[0014] Furthermore, a circuit in a broad sense is a circuit realized by at least an appropriate combination of a circuit, circuitry, a processor, a memory, etc. The processor may be a general-purpose processor or a dedicated circuit. That is, it includes application specific integrated circuits (ASICs), programmable logic devices (e.g., simple programmable logic devices (SPLDs), complex programmable logic devices (CPLDs), and field programmable gate arrays (FPGAs)), etc.

[0015] 1. Hardware Configuration of the Mobile Body 1 First, the hardware configuration of the mobile body 1 according to one embodiment will be described. FIG. 1 is a diagram illustrating an example of the overall configuration of the mobile body 1. In the following description, the directions of the mobile body 1 and each component constituting the mobile body 1 are defined based on the terms "up," "down," "left," "right," "front," and "rear" shown in FIG. 1 (as well as FIGS. 2 to 8). Furthermore, in the following description, "up" will also be referred to as "upper side" or "upper direction," and "down" will also be referred to as "lower side" or "lower." The direction formed by "up" and "down" will also be referred to as "upper" or "upper direction." The same applies to "down," "left," "right," "front," and "rear."

[0016] The moving body 1 is, for example, a rocket, an artificial satellite, a space probe, etc., and is equipped with various devices depending on its purpose, and one of the devices is a structurally and electrically connected propulsion device 100. That is, in this case, the rocket, artificial satellite, space probe, etc. is equipped with a structurally and electrically connected propulsion device 100. The moving body 1 also includes a control unit 11, a metal fuel 2, and an oxidizer 3.

[0017] (Control Unit 11) The control unit 11 includes a control unit (not shown), which performs at least control related to the propulsion device 100. The control unit is, for example, a central processing unit (CPU), not shown. The control unit realizes various functions related to the propulsion device 100 by reading out predetermined programs stored in a memory unit (not shown). Here, the control unit may be implemented as a single control unit, may be implemented with multiple control units for each function, or may be a combination thereof. The control unit 11 may be configured to execute only control related to the propulsion device 100, or may be configured to execute control related to the propulsion device 100 as part of control related to the moving body 1. When executing control related to the moving body 1, the control unit 11 may execute communication control, control related to the safety of the moving body 1, and the like, in addition to operation control related to the propulsion device 100.

[0018] (Metal fuel 2 and oxidizer 3) The metal fuel 2 and the oxidizer 3 are respectively supplied to the propulsion device 100 based on the control of the control unit 11. The metal fuel 2 and the oxidizer 3 are supplied to the propulsion device 100, and a combustion reaction occurs between the metal fuel 2 and the oxidizer 3, thereby generating a thrust for moving the moving body 1. In other words, the propulsion device 100 is a propulsion device that generates a thrust by a combustion reaction.

[0019] The metallic fuel 2 is a fuel capable of generating a propulsive force by a combustion reaction with the oxidizer 3, and is preferably made of a metallic material that can be stably handled at room temperature. Specifically, the metallic fuel 2 is preferably made of any one of magnesium, a substance containing magnesium, aluminum, and a substance containing aluminum.

[0020] Known magnesium alloys include Mg—Al alloys (AM series), Mg—Al—Zn alloys (AZ series), Mg—Zn—Zr alloys (ZK series), Mg—Cu—Zn alloys (ZC series), Mg-rare earth element-Zr alloys (EZ series), Mg-Zr-rare earth element-Ag alloys (QE series), Mg—Y-rare earth element alloys (WE series), Mg—Al—Si alloys (As) series, Mg—Al-rare earth element alloys (AE series), and Mg—Mn alloys (M series), and any of these can be used.

[0021] Known aluminum alloys include 1000 series which are pure aluminum, 2000 series which contain copper (Cu), 3000 series which contain manganese (Mn), 4000 series which contain silicon (Si), 5000 series which contain magnesium (Mg), 6000 series which contain silicon (Si) and magnesium (Mg), and 7000 series which contain zinc (Zn) and magnesium (Mg), and any of these can be used.

[0022] The shape of the metal fuel 2 is not particularly limited as long as it can be continuously supplied to the propulsion device 100, and may be, for example, wire-shaped, ribbon-shaped, or the like. The larger the cross-sectional area of ​​the metal fuel 2, the greater the propulsive force and the longer the ignition time. When the metal fuel 2 is wire-shaped, the wire diameter of the metal fuel 2 may be designed taking into account the required propulsive force and ignition time, and may be, for example, in the range of 0.05 to 5 mm. Specifically, the wire diameter of the metal fuel 2 may be 0.05, 0.1, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 11, 1.25, 1.5, 1.75, 2, 2.25, 2.5, 2.75, 3, 3.25, 3.5, 3.75, 4, 4.25, 4.5, 4.75, or 5 mm, or may be within a range between any two of the values ​​exemplified here. The metallic fuel 2 may be housed in a case (not shown) of the propulsion device 100 , or may be housed inside the moving body 1 without being housed in a case of the propulsion device 100 .

[0023] The oxidizer 3 is an oxidizer capable of generating thrust through a combustion reaction with the metal fuel 2, and may be, for example, water vapor 32 or nitrous oxide. The oxidizer 3 may be stored in a tank (not shown) arranged inside a case (not shown) of the propulsion device 100, or may be stored in a tank arranged inside the moving body 1 without being stored in the case of the propulsion device 100.

[0024] Furthermore, combustion products 4 are generated by the combustion reaction between the metal fuel 2 and the oxidizer 3. The combustion products 4 include gas 4a, which is a gas, and condensable combustion products 4b, which is a solid.

[0025] When the material of the metal wire 21 is magnesium and the oxidizing agent 3 is water vapor 32, the gas 4a is hydrogen gas and the condensable combustion product 4b is magnesium oxide. The reaction formula in this case is expressed as follows: Mg + H2O → H2 + MgO + ΔH0, ΔH0 = -359.68 kJ

[0026] When the metal wire 21 is made of aluminum and the oxidizing agent 3 is water vapor 32, the gas 4a is hydrogen gas and the condensable combustion product 4b is aluminum oxide. The reaction formula in this case is expressed as follows: 2Al + 3H2O → Al2O3 + 3H2 + ΔH0, ΔH0 = -962.32 kJ

[0027] In the following, an example will be described in which a metal wire 21 made of magnesium is used as the metal fuel 2 and water vapor 32 (water 31) is used as the oxidizer 3.

[0028] 2. Hardware Configuration of the Propulsion Device 100 Next, the hardware configuration of the propulsion device 100 according to one embodiment will be described with reference to other figures. FIG. 2 is a cross-sectional view of the propulsion device 100, as viewed from the left side, taken along the line A-A in FIG. 1B. FIG. 2 illustrates the cross-section of the propulsion device 100, thereby showing an example of the internal and external configuration of the propulsion device 100. The propulsion device 100 shown in FIG. 2 includes a combustion chamber 110, a metal fuel supply device 120, an oxidizer supply device 130, a rocket nozzle 140, an ignition device 150, a seal unit 160, and an oscillator 170. This propulsion device 100 is also referred to as a hybrid thruster, which combines both chemical combustion and electric propulsion.

[0029] (Combustion Chamber 110) As shown in Fig. 2, the combustion chamber 110 is substantially box-shaped and defines a combustion space 111 therein in which a combustion reaction can occur. That is, the combustion space 111 is a space in which the metal wire 21 and the water vapor 32 undergo a combustion reaction. In other words, the combustion chamber 110 is configured so that the water vapor 32, which is an example of the oxidizer 3, and the metal wire 21, which is an example of the metal fuel 2, undergo a combustion reaction in the combustion space 111. As a result of the combustion reaction, combustion products 4 are generated, and a thrust force for moving the mobile body 1 forward is generated by a reaction force generated by the force generated when the combustion products 4 are released to the outside of the combustion chamber 110.

[0030] 2 , the metal fuel supply device 120 includes a feed mechanism 121 and a reel 122, and is configured to supply the metal wire 21 (an example of the metal fuel 2) to the combustion space 111. Specifically, the feed mechanism 121 rotates a roller 121a under the control of the control unit 11. The rotation of the roller 121a feeds out the metal wire 21, thereby supplying the metal wire 21 sequentially to the combustion chamber 110. As the metal wire 21 is supplied to the combustion chamber 110 by the feed mechanism 121, the reel 122 rotates about its rotation axis (not shown), thereby sequentially feeding out the metal wire 21 wound around the reel 122.

[0031] The metal fuel supply device 120 is configured to supply the metal wire 21 (an example of the metal fuel 2) to the combustion space 111 at a predetermined feed rate V2. In this case, the feed rate V2 is preferably a rate corresponding to the combustion rate V1, which is the rate of the combustion reaction between the metal wire 21 and the water vapor 32. That is, the metal fuel supply device 120, based on the control of the control unit 11, may supply the metal wire 21 to the combustion chamber 110 at the feed rate V2 corresponding to the combustion rate V1, which is the rate of the combustion reaction between the metal wire 21 and the water vapor 32. Preferably, the metal fuel supply device 120, based on the control of the control unit 11, may supply the metal wire 21 at the feed rate V2 optimized for the combustion rate V1.

[0032] (Oxidant Supply Device 130) As shown in Fig. 2, the oxidant supply device 130 includes a nozzle 131 and a heater 132, and is configured to supply water vapor 32 (an example of an oxidant 3) to the combustion space 111. Specifically, the nozzle 131 has a flow path through which water 31 can flow, and the water 31 flows through the flow path to supply the water 31 from outside the combustion chamber 110 into the combustion space 111. The nozzle 131 also supplies the water 31 so that the water 31 supplied into the combustion space 111 gathers at a position 112 in the combustion chamber 110. The heater 132, which is provided outside the combustion chamber 110, generates heat, which heats the water 31 collected at the position 112, thereby heating the water 31. That is, the heater 132 is configured to heat the water 31 that has gathered at the position 112 of the combustion chamber 110 from outside the combustion chamber 110, based on the control of the control unit 11. Note that the configuration of the oxidizer supply device 130 is not limited to this, and the water 31 may be vaporized outside the combustion chamber 110, and the water vapor 32 may be supplied into the combustion space 111.

[0033] (Rocket Nozzle 140) As shown in Figure 2, a rocket nozzle 140 is connected to the combustion chamber 110. In addition, the combustion chamber 110 and the rocket nozzle 140 form a combustion product passage 141 that connects the outside of the combustion chamber 110 to the combustion space 111. In other words, the combustion space 111 connects to the outside of the combustion chamber 110 via the rocket nozzle 140. In other words, the rocket nozzle 140 is configured to release the combustion products 4 generated by the combustion reaction from the combustion space 111 to the outside of the combustion chamber 110 via the combustion product passage 141 that connects the outside of the combustion chamber 110 to the combustion space 111.

[0034] The combustion product passage 141 may be configured to accelerate the combustion products 4 discharged from the combustion space 111 to the outside of the combustion chamber 110. Specifically, as shown in FIG. 2 , the combustion product passage 141 has a smallest cross-sectional area at a position 141a near the boundary between the combustion chamber 110 and the rocket nozzle 140 in a cross section defined by the vertical and horizontal directions. The cross-sectional area of ​​the combustion product passage 141 increases from the position 141a toward the rear. This allows the conditions within the combustion space 111 to be adjusted to any desired temperature and pressure. Furthermore, the gas 4a generated within the combustion space 111 expands and increases in velocity as it passes the position 141a and moves rearward. This increases the reaction force of the combustion products 4 discharged to the outside of the combustion chamber 110, thereby effectively generating a propulsive force for the vehicle 1 to move forward.

[0035] (Ignition Device 150) The ignition device 150 is a mechanism for heating the metal wire 21 to initiate a combustion reaction between the metal wire 21 and the water vapor 32. The ignition device 150 shown in FIG. 2 ignites the metal wire 21 using electrical discharge. Specifically, the ignition device 150 includes an electrode 151, a high-voltage generating circuit 152, a voltage source 153, and a switch SW1. The electrode 151 is disposed to face the tip portion 21a of the metal wire 21 supplied into the combustion space 111. The high-voltage generating circuit 152 is configured to apply a pulsed high voltage between the metal wire 21 and the electrode 151. The application of the high voltage generates a strong electric field in the gap between the metal wire 21 and the electrode 151, causing a dielectric breakdown. An arc discharge caused by the dielectric breakdown raises the temperature of the tip portion 21a of the metal wire 21 to a temperature higher than the ignition point. This initiates a combustion reaction between the metal wire 21 and the water vapor 32 in the combustion space 111. The switch SW1 may be turned off during the combustion reaction. To stop the combustion reaction, the metal fuel supply device 120 may stop feeding the metal wire 21 and stop supplying the water vapor 32.

[0036] 2 , the roller 121a of the delivery mechanism 121 is made of metal, and the metal wire 21 and the voltage source 153 are electrically connected via the roller 121a. The switch SW1 is configured to be able to be turned on and off, and when the switch SW1 is turned on, a high voltage is applied between the electrode 151 and the metal wire 21.

[0037] (Sealing portion 160) The sealing portion 160 has a passage through which the metal wire 21 (an example of the metal fuel 2) can pass, and is a mechanism that prevents gas 4a of the combustion products 4 generated in the combustion space 111 of the combustion chamber 110 from leaking outside the combustion space 111. The sealing portion 160 shown in FIG. 2 is fixed to the wall of the combustion chamber 110 and may be a combination of a grease seal (not shown), a mechanical seal 161, a labyrinth seal (not shown), or the like. The grease seal may include a grease pod and grease filled in the grease pod. The mechanical seal 161 has a sleeve, and the sleeve may be made of, for example, Teflon (registered trademark). The labyrinth seal may be made of ceramic.

[0038] (Oscillator 170) The oscillator 170 is configured to operate to vibrate the metal wire 21 supplied to the combustion space 111 during the combustion reaction. In other words, the metal wire 21 (an example of the metal fuel 2) supplied to the combustion space 111 extends in the combustion space 111, causing a combustion reaction, and vibrates during the combustion reaction as a result of operation of at least a portion of the propulsion device 100. Note that in this case, the operation of at least a portion of the propulsion device 100 is the operation of the oscillator 170 included in the propulsion device 100. In other words, the operation of the oscillator 170 included in the propulsion device 100 is an example of the operation of at least a portion of the propulsion device 100. According to this aspect, the condensable combustion products 4b generated by the combustion reaction can be atomized using safe metal wire 21 and water 31 (steam 32). Furthermore, atomization of the condensable combustion products 4b allows the condensable combustion products 4b to pass smoothly through the position 141a of the combustion product passage 141 where the cross-sectional area is smallest. In this case, the condensable combustion products 4b are preferably atomized into particles of 1 mm or less in size. According to this embodiment, the heat of the atomized particles can be efficiently transferred to the gas 4a, and furthermore, the heat is smoothly released to the outside of the propulsion device 100 along with the flow of the gas 4a, thereby preventing a decrease in the thrust of the propulsion device 100. Furthermore, in the case of particles of 1 mm or less in size, the load that the particles impose on outer space can be reduced.

[0039] In addition, in the propulsion device 100 shown in Figure 2, the vibrating body 170 is configured to vibrate, and the vibration of the vibrating body 170 causes the metal wire 21 (an example of the metal fuel 2) to vibrate in the combustion space 111.

[0040] Specifically, the vibrating body 170 includes a vibration source 171 , a base 172 , a movable metal 173 , and a rod 174 .

[0041] The vibration source 171 is configured to vibrate the gantry 172, and specifically, is an eccentric motor that operates based on the control of the control unit 11. The eccentric motor rotates while in contact with the gantry 172, thereby vibrating the gantry 172.

[0042] The base 172 is connected to the movable metal 173 and the rod 174 , that is, the movable metal 173 and the rod 174 are excited by the excitation source 171 via the base 172 .

[0043] The movable metal 173 is configured to maintain airtightness while deforming in response to vibration, and is, for example, a bellows.

[0044] The rod 174 is generally rod-shaped and has a contact portion 174a that comes into contact with the metal wire 21. When the rod 174 is vibrated by the vibration source 171 via the stand 172, the contact portion 174a comes into contact with the metal wire 21, causing the metal wire 21 to vibrate. In other words, the contact portion 174a is configured to come into contact with the metal wire 21 when vibrated, and may be, for example, a hole or groove through which the metal wire 21 can be inserted.

[0045] Furthermore, the vibrating body 170 may start vibrating in response to the start of a combustion reaction between the metal wire 21 and the water vapor 32, based on the control of the control unit 11. According to this embodiment, the condensable combustion products 4b generated in response to the start of the combustion reaction can be atomized at an optimal timing.

[0046] Furthermore, the propulsion device 100 may be configured to vibrate the metal wire 21 (an example of the metal fuel 2) supplied to the combustion space 111 in accordance with the natural frequency of the metal wire 21. In this case, the natural frequency may be predetermined based on the length of the metal wire 21 extending in the combustion space 111, the shape of the metal wire 21, and the like. Specifically, the vibrating body 170 vibrates at a frequency corresponding to the predetermined natural frequency under control of the control unit 11. The vibrating body 170 may vibrate at a constant frequency or may vibrate so as to vary within a predetermined frequency range. The frequency corresponding to the predetermined natural frequency may be determined based on the structure of the propulsion device 100, the positional relationship between the vibrating body 170 and the metal wire 21, and the like. For example, the frequency may be approximately the same as the natural frequency or a frequency lower than the natural frequency. According to this embodiment, the condensable combustion products 4b generated by the combustion reaction can be more efficiently atomized.

[0047] Furthermore, the rod 174 is disposed so as to extend into the combustion space 111. In other words, the rod 174 of the vibrating body 170 is provided so as to be positioned in the combustion space 111, and is configured to vibrate the metal wire 21 (an example of the metal fuel 2) by contacting the metal wire 21. According to this embodiment, the rod 174 of the vibrating body 170 comes into contact with the metal wire 21, thereby making it possible to vibrate the metal wire 21, thereby atomizing the condensable combustion products 4b generated by the combustion reaction.

[0048] 2, the metal wire 21 extends from the front to the rear of the combustion space 111, and the rod 174 of the vibrating body 170 is configured to vibrate in the up-and-down direction. That is, the vibrating body 170 vibrates the metal wire 21 in a direction perpendicular to the front-to-rear direction in which the metal wire 21 extends (the up-and-down direction). That is, at the tip end portion 21a of the metal wire 21, a shear force is generated in the condensable combustion products 4b generated by the combustion reaction. In other words, the metal wire 21 (an example of the metal fuel 2) vibrates in a direction that generates a shear force in the metal wire 21 as a result of the operation of at least a part of the propulsion device 100. According to this configuration, the condensable combustion products 4b generated by the combustion reaction can be more efficiently atomized.

[0049] [Others] The moving body 1 according to an embodiment can also be implemented in the following manner.

[0050] Figures 3 to 8 are cross-sectional views of another example of the propulsion device 100 shown in Figure 2, taken from the left side of the propulsion device 100 in the state shown on the A-A cross section in Figure 1B. Figure 9 is a graph showing an example of the feed speed V2 when the metal fuel 2 is supplied at a constant speed in Figure 9A, and a graph showing an example of the feed speed V2 when the metal fuel 2 is supplied while accelerating and decelerating in Figure 9B.

[0051] 2, the metal wire 21 is vibrated by the rod 174 of the vibrating body 170, but the present invention is not limited to this. For example, the present invention may be implemented in the following manner.

[0052] <Excitation of the Entire Combustion Chamber 110> As shown in Figures 3 and 4, the oscillator 170 may be connected to the outside of the combustion chamber 110, thereby vibrating the entire combustion chamber 110. That is, the oscillator 170 may vibrate the combustion chamber 110 so that the entire combustion chamber 110 vibrates, thereby vibrating the metal fuel 2 in the combustion space 111. According to this embodiment, vibrating the entire combustion chamber 110 makes it possible to vibrate the metal fuel 2 therein, thereby atomizing the condensable combustion products 4b generated by the combustion reaction. The propulsion device 100 shown in Figure 3 and the propulsion device 100 shown in Figure 4 differ in the number and arrangement of the oscillators 170. The propulsion device 100 shown in Figure 3 will be described below, starting with the propulsion device 100 shown in Figure 3.

[0053] In the propulsion device 100 shown in FIG. 3, one vibrating body 170 is disposed above the combustion chamber 110 .

[0054] Specifically, the vibrating body 170 disposed above the combustion chamber 110 includes a vibration source 171 and a base 172. The vibration source 171 is connected at its lower side to the combustion chamber 110 and at its upper side to the base 172. That is, the vibration source 171 is disposed between the combustion chamber 110 and the base 172. The vibration source 171 is configured to expand and contract in the vertical direction based on control by the control unit 11, and may be, for example, a laminated piezoelectric actuator. Furthermore, the base 172 has limited movement relative to the combustion chamber 110. That is, in this case, the vibration source 171 repeatedly expands and contracts in the vertical direction, causing the combustion chamber 110 to repeatedly reciprocate in the vertical direction relative to the base 172. As a result, the metal wire 21 extending within the combustion space 111 of the combustion chamber 110 is vibrated.

[0055] In the propulsion device 100 shown in FIG. 4, one vibrator 170 is disposed above and one below the combustion chamber 110 .

[0056] Specifically, the vibrating body 170 of the propulsion device 100 shown in Fig. 4 has vibrating body 170a and vibrating body 170b. Vibrating body 170a is disposed above the combustion chamber 110 and includes a vibration source 171a (an example of vibration source 171) and a mount 172a (an example of mount 172). Vibrating body 170b is disposed below the combustion chamber 110 and includes a vibration source 171b (an example of vibration source 171) and a mount 172b (an example of mount 172). In other words, the vibrating bodies 170 in this case are disposed above and below the combustion chamber 110 so as to face each other.

[0057] Furthermore, the vibration source 171a has a lower side connected to the combustion chamber 110 and an upper side connected to the base 172a, and the vibration source 171b has an upper side connected to the combustion chamber 110 and a lower side connected to the base 172b. The vibration sources 171a and 171b are configured to expand and contract in the vertical direction based on control by the control unit 11, and for example, laminated piezoelectric actuators may be used. The expansion and contraction in the vertical direction by the vibration sources 171a and 171b may be out of phase. For example, the vibration sources 171a and 171b may expand and contract in conjunction with each other so that the vibrated combustion chamber 110 is displaced in one vertical direction.

[0058] Furthermore, the movement of the frame 172 relative to the combustion chamber 110 is restricted. That is, in this case, the vibration sources 171a and 171b are linked together to repeatedly expand and contract in the vertical direction, causing the combustion chamber 110 to repeatedly move back and forth in the vertical direction relative to the frame 172. As a result, the metal wire 21 extending into the combustion space 111 of the combustion chamber 110 is vibrated. According to this embodiment, it is possible to more effectively vibrate the entire combustion chamber 110, and the condensable combustion products 4b generated by the combustion reaction can be more efficiently atomized.

[0059] <Exciting the seal portion 160> Alternatively, as shown in Figures 5 and 6, the vibrating body 170 may excite the seal portion 160, thereby vibrating the metal wire 21 passing through the seal portion 160. That is, the vibrating body 170 may be configured to excite the seal portion 160, thereby vibrating the metal fuel 2 in the combustion space 111. According to this embodiment, vibrating the seal portion 160 makes it possible to vibrate the metal fuel 2, thereby atomizing the condensable combustion products 4b generated by the combustion reaction. The propulsion device 100 shown in Figure 5 and the propulsion device 100 shown in Figure 6 differ in the direction in which the seal portion 160 is displaced relative to the pedestal 172 and the combustion chamber 110. The propulsion device 100 shown in Figure 5 will be described first.

[0060] The propulsion device 100 shown in FIG. 5 is configured so that the seal portion 160 repeatedly moves back and forth in the up and down direction relative to the mount 172 and the combustion chamber 110 .

[0061] Specifically, in the propulsion device 100 shown in FIG. 5 , the seal unit 160 is disposed in front of the combustion chamber 110, and the metal wire 21 is inserted through the mechanical seal 161 of the seal unit 160 in the front-rear direction. In other words, the seal unit 160 is configured to abut against the periphery of the combustion chamber 110, thereby supplying the metal wire 21 (an example of metal fuel 2) to the combustion space 111 through a passage. In addition, a vibrating body 170 is connected above the seal unit 160, thereby enabling the seal unit 160 to move back and forth in the vertical direction relative to the combustion chamber 110. The vibrating body 170 is located above the seal unit 160 and includes a vibration source 171 and a mount 172. One end of the vibration source 171 is connected to the seal unit 160, and the other end is connected to the mount 172. The vibration source 171 is configured to expand and contract in the vertical direction based on control by the control unit 11, and may be, for example, a stacked piezoelectric actuator. Furthermore, the movement of the mount 172 relative to the combustion chamber 110 is restricted. That is, in this case, as the vibration source 171 repeatedly expands and contracts in the vertical direction, the seal portion 160 repeatedly undergoes vertical reciprocating displacement relative to the mount 172 and the combustion chamber 110. As a result, the metal wire 21 is vibrated by the vibrating body 170 via the seal portion 160.

[0062] 5, the propulsion device 100 shown in Fig. 6 differs from the propulsion device 100 shown in Fig. 5 in the configuration of the vibrating body 170 and the positional relationship between the seal portion 160 and the vibrating body 170. As a result, the propulsion device 100 shown in Fig. 6 is configured so that the seal portion 160 repeatedly moves back and forth in the front-to-rear direction relative to the pedestal 172 and the combustion chamber 110.

[0063] Specifically, in the propulsion device 100 shown in FIG. 6 , the vibrating body 170 includes a vibration source 171, a mount 172, and a movable metal 173. The vibration source 171 and the mount 172 are disposed in front of the seal portion 160, and the movable metal 173 is disposed behind the seal portion 160. One end of the vibration source 171 is connected to the seal portion 160, and the other end is connected to the mount 172. The vibration source 171 is configured to expand and contract in the front-rear direction based on control by the control unit 11, and may be, for example, a laminated piezoelectric actuator. Furthermore, the mount 172 has limited movement relative to the combustion chamber 110. The movable metal 173 is disposed between the combustion chamber 110 and the seal portion 160 and is connected so as to be displaceable in the front-rear direction. The seal portion 160 is disposed in front of the combustion chamber 110, and the movable metal 173 is connected between the combustion chamber 110 and the seal portion 160. As a result, the seal portion 160 is configured to be able to move back and forth in the front-to-rear direction relative to the combustion chamber 110 while preventing the gas 4a of the combustion products 4 from leaking outside the combustion space 111. The metal wire 21 is inserted through the mechanical seal 161 of the seal portion 160 in the front-to-rear direction. The mechanical seal 161 is preferably configured to generate a predetermined frictional force with respect to the metal wire 21. With this configuration, the seal portion 160 repeatedly moves back and forth in the front-to-rear direction relative to the base 172 and the combustion chamber 110 as the vibration source 171 repeatedly expands and contracts in the front-to-rear direction. As a result, the metal wire 21 is vibrated by the vibrating body 170 via the seal portion 160.

[0064] <Excitation by Sound Waves W> Furthermore, as shown in Fig. 7 , the metal wire 21 may be vibrated by sound waves W generated in the combustion space 111. In this case, the combustion chamber 110 may generate sound waves W in the combustion space 111 inside the combustion chamber 110 by vibrating the wall of the combustion chamber 110. In other words, the vibrating body 170 may be configured to vibrate at least a portion of the combustion chamber 110, thereby vibrating the metal wire 21 (an example of the metal fuel 2) by the sound waves W generated in the combustion space 111. According to this embodiment, it is possible to vibrate the metal wire 21 by the sound waves W, thereby atomizing the condensable combustion products 4b generated by the combustion reaction.

[0065] Specifically, the combustion chamber 110 has a thin-walled portion 113 as an upper wall portion of the combustion chamber 110. The thin-walled portion 113 is thinner than the other wall portions. The vibrating body 170 is disposed above the thin-walled portion 113 and includes a vibration source 171 and a base 172. The vibration source 171 is connected at its lower side to the combustion chamber 110 and at its upper side to the base 172. The vibration source 171 is configured to vibrate the thin-walled portion 113 in the vertical direction based on control by the control unit 11. For example, a piezoelectric element, an electromagnet, or the like may be used. Furthermore, the base 172 is limited in its movement relative to the combustion chamber 110. In other words, in this case, the vibration source 171 vibrates the thin-walled portion 113 in the vertical direction, i.e., the thin-walled portion 113 resonates with its wall surface, generating sound waves W within the combustion space 111. As a result, the metal wire 21 is vibrated by the sound waves W generated in the combustion space 111 .

[0066] <Vibration Based on Feed Speed ​​V2> As shown in FIG. 8, the metal wire 21 may be vibrated based on the feed speed V2 of the metal wire 21.

[0067] Specifically, the feeding mechanism 121 may be configured to change the feed speed V2. In this case, the feeding mechanism 121 feeds the metal wire 21 at a substantially constant feed speed (feed speed V21) before the combustion reaction between the metal wire 21 and the water vapor 32 starts, as shown in FIG. 9A . After that, when the combustion reaction between the metal wire 21 and the water vapor 32 starts, the metal wire 21 is fed while the feed speed V2 changes between a first speed V2a and a second speed V2b as time T elapses, as shown in FIG. 9B . The change in the feed speed V2 between the first speed V2a and the second speed V2b causes vibrations in the metal wire 21. In other words, the feed speed V2, which is a predetermined speed, may include at least a first speed V2a and a second speed V2b different from the first speed V2a. In this case, the change in speed between the first speed V2a and the second speed V2b causes the metal fuel 2 to vibrate in the direction in which the metal fuel 2 extends in the combustion space 111. According to this embodiment, the metal fuel 2 can be vibrated by changing the supply speed of the metal fuel supply device 120, thereby atomizing the condensable combustion products 4b generated by the combustion reaction. Note that in this case, the operation of at least a portion of the propulsion device 100 is the operation of the metal fuel supply device 120 provided in the propulsion device 100. In other words, the operation of the metal fuel supply device 120 provided in the propulsion device 100 is an example of the operation of at least a portion of the propulsion device 100.

[0068] Furthermore, the feed speed V2 may be changed using the frictional force of the mechanical seal 161 of the seal unit 160. Specifically, the mechanical seal 161 may be configured so that the state of friction between the mechanical seal 161 and the metal wire 21 is in an arbitrary state. In this case, the arbitrary state is set so that, when the feed mechanism 121 feeds out the metal wire 21 at the feed speed V2, the mechanical seal 161 repeatedly slips, stops, and then slips due to changes in the frictional force generated between the mechanical seal 161 and the metal wire 21 in contact with the mechanical seal 161. Note that the feed speed V2 in this case may be a substantially constant feed speed V21, or may be a feed speed V2 that varies between a first speed V2a and a second speed V2b. This configuration causes vibrations in the metal wire 21. In other words, when the metal fuel supply device 120 supplies the metal fuel 2, the metal fuel 2 vibrates in the combustion space 111 due to frictional force generated by contact between the metal fuel 2 and a portion of the propulsion device 100. According to this aspect, the metal fuel 2 can be vibrated by the frictional force generated when the metal fuel 2 is supplied, thereby atomizing the condensable combustion products 4b generated by the combustion reaction. Note that in this case, the operation of at least a portion of the propulsion device 100 is the operation of the metal fuel supply device 120 provided in the propulsion device 100. In other words, the operation of the metal fuel supply device 120 provided in the propulsion device 100 is an example of the operation of at least a portion of the propulsion device 100.

[0069] Furthermore, it may be provided in the following aspects.

[0070] (1) A propulsion device that generates thrust through a combustion reaction, comprising: a combustion chamber; and a metal fuel supply device, wherein the combustion chamber forms a combustion space within which the combustion reaction can occur; the metal fuel supply device is configured to supply metal fuel to the combustion space; the supplied metal fuel extends in the combustion space, causes the combustion reaction, and is configured to vibrate during the combustion reaction as a result of operation of at least a portion of the propulsion device.

[0071] According to this embodiment, it is possible to atomize condensable combustion products produced by the combustion reaction while using safe fuel and oxidizer.

[0072] (2) The propulsion device according to (1) above, further comprising a vibrating body, the vibrating body being configured to vibrate, and the metal fuel vibrating in the combustion space due to the vibration of the vibrating body.

[0073] According to this aspect, the metal fuel can be vibrated due to the vibration of the vibrating body, and this makes it possible to atomize the condensable combustion products produced by the combustion reaction.

[0074] (3) The propulsion device according to (2) above, wherein the vibrating body vibrates the combustion chamber so that the entire combustion chamber vibrates, thereby vibrating the metal fuel in the combustion space.

[0075] According to this embodiment, by vibrating the entire combustion chamber, it is possible to vibrate the metal fuel therein, thereby atomizing the condensable combustion products produced by the combustion reaction.

[0076] (4) The propulsion device according to (2) above, wherein the vibrating body is provided to be positioned in the combustion space and configured to vibrate the metal fuel by coming into contact with the metal fuel.

[0077] According to this aspect, the vibrating body comes into contact with the metal fuel, thereby vibrating the metal fuel, and thereby atomizing the condensable combustion products produced by the combustion reaction.

[0078] (5) The propulsion device described in (2) above further includes a seal portion, the seal portion having a passage through which the metal fuel can pass and configured to abut against the periphery of the combustion chamber, thereby supplying the metal fuel to the combustion space through the passage, and the vibrating body configured to vibrate the seal portion, thereby vibrating the metal fuel in the combustion space.

[0079] According to this aspect, it is possible to vibrate the metal fuel by vibrating the seal portion, thereby atomizing the condensable combustion products produced by the combustion reaction.

[0080] (6) In the propulsion device described in (2) above, the vibrator is configured to vibrate at least a portion of the combustion chamber, thereby vibrating the metal fuel due to sound waves generated in the combustion space.

[0081] According to this embodiment, the metallic fuel can be vibrated by the sound waves, thereby atomizing the condensable combustion products produced by the combustion reaction.

[0082] (7) The propulsion device according to any one of (1) to (6) above, wherein the metal fuel vibrates in a direction that generates a shear force in the metal fuel as a result of operation of at least a part of the propulsion device.

[0083] According to this embodiment, the condensable combustion products produced by the combustion reaction can be more efficiently atomized.

[0084] (8) A thruster according to any one of (1) to (6) above, wherein the metal fuel supply device is configured to supply the metal fuel to the combustion space at a predetermined speed, wherein the predetermined speed includes at least a first speed and a second speed different from the first speed, and the change in speed between the first speed and the second speed causes the metal fuel to vibrate in the direction in which the metal fuel extends in the combustion space.

[0085] According to this aspect, it is possible to vibrate the metal fuel by changing the supply speed of the metal fuel supply device, thereby atomizing the condensable combustion products produced by the combustion reaction.

[0086] (9) A thruster according to any one of (1) to (6) above, wherein when the metal fuel supply device supplies the metal fuel, frictional force generated by contact between the metal fuel and a part of the thruster causes the metal fuel to vibrate in the combustion space.

[0087] According to this aspect, the frictional force generated when the metal fuel is supplied can vibrate the metal fuel, thereby atomizing the condensable combustion products produced by the combustion reaction.

[0088] (10) The propulsion device according to any one of (1) to (9) above, wherein the propulsion device is configured to vibrate the metal fuel in accordance with a natural frequency of the metal fuel supplied to the combustion space.

[0089] According to this embodiment, the condensable combustion products produced by the combustion reaction can be more efficiently atomized.

[0090] (11) The thruster according to any one of (1) to (10) above, wherein the metal fuel is made of any one of magnesium, a substance containing magnesium, aluminum, and a substance containing aluminum.

[0091] According to this embodiment, it is possible to employ a safe metal fuel while atomizing condensable combustion products produced by the combustion reaction.

[0092] (12) A propulsion device according to any one of (1) to (11) above, further comprising an oxidizer supply device configured to supply an oxidizer to the combustion space, wherein the oxidizer is water vapor or nitrous oxide, and the oxidizer and the metal fuel cause the combustion reaction in the combustion space.

[0093] According to this embodiment, it is possible to atomize condensable combustion products produced by the combustion reaction while employing a safe oxidizing agent.

[0094] (13) A rocket comprising a structurally and electrically connected propulsion device, the propulsion device being the propulsion device described in any one of (1) to (12) above.

[0095] According to this aspect, it is possible to provide a technology relating to a rocket equipped with a propulsion device that can atomize condensable combustion products produced by a combustion reaction while using safe fuel and oxidizer.

[0096] (14) An artificial satellite comprising a structurally and electrically connected propulsion device, the propulsion device being a propulsion device described in any one of (1) to (12) above.

[0097] According to this aspect, it is possible to provide a technology relating to an artificial satellite equipped with a thruster that can atomize condensable combustion products generated by a combustion reaction while using safe fuel and oxidizer.

[0098] (15) A space probe comprising a structurally and electrically connected propulsion device, the propulsion device being a propulsion device described in any one of (1) to (12) above.

[0099] According to this aspect, it is possible to provide a technology relating to a space probe equipped with a thruster that can atomize condensable combustion products generated by a combustion reaction while using safe fuel and oxidizer.

[0100] Finally, while various embodiments of the present invention have been described, these are presented by way of example only and are not intended to limit the scope of the invention. The novel embodiments may be embodied in various other forms, and various omissions, substitutions, and modifications may be made without departing from the spirit of the invention. Such embodiments and modifications are intended to be included within the scope and spirit of the invention, as well as within the scope of the inventions and their equivalents as defined in the accompanying claims.

[0101] 1: Mobile body, 11: Control unit, 2: Metal fuel, 21: Metal wire, 21a: Tip portion, 3: Oxidizer, 31: Water, 32: Water vapor, 4: Combustion products, 4a: Gas, 4b: Condensable combustion products, 100: Thruster, 110: Combustion chamber, 111: Combustion space, 112: Position, 113: Thin portion, 120: Metal fuel supply device, 121: Delivery mechanism, 121a: Roller, 122: Reel, 130: Oxidizer supply device, 131: Nozzle, 132: Heater, 140: Rocket nozzle, 141: Combustion product passage, 141a: Position Position, 150: Ignition device, 151: Electrode, 152: High voltage generating circuit, 153: Voltage source, 160: Seal portion, 161: Mechanical seal, 170: Vibrator, 170a: Vibrator, 170b: Vibrator, 171: Vibration source, 171a: Vibration source, 171b: Vibration source, 172: Stand, 172a: Stand, 172b: Stand, 173: Movable metal, 174: Rod, 174a: Contact portion, SW1: Switch, T: Time, V1: Burning speed, V2: Feed speed, V21: Feed speed, V2a: First speed, V2b: Second speed, W: Sound wave

Claims

1. A propulsion device that generates thrust through a combustion reaction, comprising: a combustion chamber; and a metal fuel supply device, wherein the combustion chamber defines a combustion space within which the combustion reaction can occur; and the metal fuel supply device is configured to supply metal fuel to the combustion space, the supplied metal fuel extending within the combustion space and causing the combustion reaction, and configured to vibrate during the combustion reaction as a result of operation of at least a portion of the propulsion device.

2. A thruster according to claim 1, further comprising a vibrating body, the vibrating body being configured to vibrate, and the metal fuel vibrating in the combustion space due to the vibration of the vibrating body.

3. A thruster according to claim 2, wherein the vibrating body vibrates the combustion chamber so that the entire combustion chamber vibrates, thereby vibrating the metal fuel in the combustion space.

4. A thruster according to claim 2, wherein the vibrating body is provided so as to be positioned in the combustion space and is configured to vibrate the metal fuel by coming into contact with the metal fuel.

5. A propulsion device as set forth in claim 2, further comprising a seal portion, the seal portion having a passage through which the metal fuel can pass and configured to abut against the periphery of the combustion chamber, thereby supplying the metal fuel to the combustion space via the passage, and the vibrating body configured to vibrate the seal portion, thereby vibrating the metal fuel in the combustion space.

6. A thruster according to claim 2, wherein the vibrating body is configured to vibrate at least a part of the combustion chamber, thereby vibrating the metal fuel due to sound waves generated in the combustion space.

7. A thruster according to any one of claims 1 to 6, wherein the metal fuel vibrates in a direction that generates a shear force in the metal fuel as a result of operation of at least a part of the thruster.

8. A thruster according to any one of claims 1 to 6, wherein the metal fuel supply device is configured to supply the metal fuel to the combustion space at a predetermined speed, wherein the predetermined speed includes at least a first speed and a second speed different from the first speed, and wherein the change in speed between the first speed and the second speed causes the metal fuel to vibrate in the direction in which the metal fuel extends in the combustion space.

9. A thruster according to any one of claims 1 to 6, wherein, when the metal fuel supply device supplies the metal fuel, frictional force is generated when the metal fuel comes into contact with a part of the thruster, causing the metal fuel to vibrate in the combustion space.

10. A thruster according to any one of claims 1 to 9, configured to vibrate the metal fuel in accordance with the natural frequency of the metal fuel supplied to the combustion space.

11. A thruster according to any one of claims 1 to 10, wherein the metallic fuel is made of any one of magnesium, a substance containing magnesium, aluminum, and a substance containing aluminum.

12. A propulsion device according to any one of claims 1 to 11, further comprising an oxidizer supply device configured to supply an oxidizer to the combustion space, wherein the oxidizer is water vapor or nitrous oxide, and the oxidizer and the metal fuel cause the combustion reaction in the combustion space.

13. A rocket comprising a propulsion device structurally and electrically connected thereto, the propulsion device being a propulsion device according to any one of claims 1 to 12.

14. An artificial satellite comprising a structurally and electrically connected propulsion device, the propulsion device being a propulsion device according to any one of claims 1 to 12.

15. A space probe comprising a propulsion device structurally and electrically connected thereto, the propulsion device being a propulsion device according to any one of claims 1 to 12.

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