Multi-start ignition system and ignition method for liquid rocket engine

Abstract

The liquid rocket engine multi-starting ignition system comprises a support and a base, the support is fixedly connected with the base, a servo motor is fixedly connected to the support, an output shaft of the servo motor is sequentially connected with a first gear and an ignition device, and a percussion device is arranged on the side face of the servo motor. The percussion device is fixedly connected to the side face of the servo motor shell through a guide rail frame. Under the condition that the number of gunpowder starters is not increased, multiple times of ignition on the rocket are achieved; and meanwhile, the reliability of the rocket is enhanced, even if a certain igniter breaks down, other igniters can still work normally, and it is guaranteed that the rocket launching task is completed.

Description

Technical Field

[0001] This invention belongs to the field of aerospace propulsion technology, and relates to a liquid rocket engine multiple-start ignition system and a method for multiple-start ignition of a liquid rocket engine. Background Technology

[0002] With the industrialization and commercialization of space technology, space launch vehicles should aim for complete reusability to reduce costs. This requires the engines of space launch vehicles to be able to reliably start and ignite multiple times. As the external energy source for the starting and ignition of traditional liquid rocket engines, the mainstream approach in China currently mostly uses gunpowder starters. The principle is that when the engine starts, a small solid rocket motor is ignited by an electric detonator. The combustion of its propellant column produces high-temperature, high-pressure gas, which drives the turbine of the liquid rocket motor to a predetermined operating condition, thereby starting the engine. This small solid rocket motor is called a gunpowder starter. However, if a multi-start engine uses this method, multiple gunpowder starter devices are required, which increases the engine weight and reduces the engine's thrust-to-weight ratio. Summary of the Invention

[0003] The first objective of this invention is to provide a multiple-start ignition system for a liquid rocket engine, which solves the problem in the prior art that using gunpowder starters to start the engine multiple times requires multiple gunpowder starter devices, resulting in increased engine weight and reduced engine thrust-to-weight ratio.

[0004] The second objective of this invention is to provide a method for multiple ignition starts of a liquid rocket engine.

[0005] The first technical solution adopted in this invention is a liquid rocket engine multiple start-up ignition system, including a bracket and a base. The bracket and the base are fixedly connected. A servo motor is fixedly connected to the bracket. The output shaft of the servo motor is sequentially connected to a first gear and an ignition device. A firing device is provided on the side of the servo motor. The firing device is fixedly connected to the side of the servo motor housing through a guide rail frame.

[0006] The invention is further characterized by: The ignition device includes an igniter slot, which is fixedly connected to the end of the output shaft of the servo motor. The igniter slot is a cylindrical structure and is coaxial with the servo motor. The igniter slot has several through holes along its axial direction, and these through holes are evenly arranged around the axis of the igniter slot. An igniter is fixed in each through hole.

[0007] A mounting shaft is fixedly connected to the side of the servo motor. The mounting shaft is connected to the second gear of the firing device through a rolling bearing. The second gear meshes perpendicularly with the first gear for transmission. A rotating lever is fixedly connected to the eccentric position on the side of the second gear disc opposite to the servo motor. A guide rail is fixedly connected to the guide rail frame along its length. The firing pin of the firing device is sleeved inside the guide rail. A semi-circular slide groove is fixedly connected to the end of the firing pin near the second gear. The semi-circular slide groove is slidably connected to the rotating lever.

[0008] The second gear has the same module as the first gear, and the gear ratio between the second gear and the first gear is set according to the following formula:

[0009] in That is the number of teeth on the first gear. That is the number of teeth on the second gear. It refers to the number of igniters installed in the igniter slot.

[0010] The eccentricity of the rotating lever is 0.2-0.8 times the radius of the root circle of the second gear, and the radius of the semi-circular groove is the same as the eccentricity of the rotating lever.

[0011] A fuel injection port is provided at the bottom of the base, located directly below the firing pin. The shape and size of the fuel injection port are the same as the shape and size of the igniter's cross-section.

[0012] The igniter includes a housing and a cover. The cover is movably disposed at one end of the housing near the firing pin. The other end of the housing is sealed with a sealing diaphragm. A spring is fixedly connected inside the cover, and the other end of the spring abuts against the firing cap. A solid propellant is filled between the firing cap and the sealing diaphragm. The firing cap, the sealing diaphragm, and the inner wall of the housing together form a sealed space. The solid propellant is a magnesium / polytetrafluoroethylene igniter.

[0013] The igniter also includes an upper limit ring and a lower limit ring, which are fixed to the inner wall of the housing. The upper limit ring is adjacent to the firing cap, which is located between the upper limit ring and the lower limit ring.

[0014] The lower limit ring has an annular groove, and the lower end face of the firing cap has a coaxial annular protrusion that matches the annular groove. The annular groove contains graphite particles with a particle size of 50μm-100μm.

[0015] The second technical solution adopted in this invention, a method for multiple ignitions of a liquid rocket engine, comprises the following steps: Step 1: Determine the number of igniters based on the number of ignitions required for the rocket launch mission. The number of igniters should be the same as the number of ignitions. Step 2: Determine the gear ratio of the first gear and the second gear based on the number of igniters; Step 3: Determine the eccentricity of the rotating lever on the second gear. The eccentricity should be greater than the distance between the bottom of the firing pin and the firing cap of the igniter, and the eccentricity should be selected between 0.2 and 0.8 times the radius of the root circle of the second gear.

[0016] The beneficial effects of this invention are: it enables multiple ignitions of the rocket without increasing the number of propellant igniters; at the same time, it enhances the reliability of the rocket, so that even if one igniter fails, the other igniters can still work normally, ensuring the completion of the mission. Attached Figure Description

[0017] Figure 1 This is a three-dimensional view of the liquid rocket engine multiple-start ignition system of the present invention; Figure 2 This is a top view of the liquid rocket engine multiple-start ignition system of the present invention; Figure 3 This is a front view of the igniter of the liquid rocket engine multiple-start ignition system of the present invention; In the diagram: 1. Bracket, 2. Servo motor, 3. First gear, 4. Second gear, 5. Guide rail bracket, 6. Guide rail, 7. Firing pin, 8. Semi-circular groove, 9. Output shaft, 10. Igniter, 11. Igniter slot, 12. Base, 13. Housing, 14. Upper limit ring, 15. Firing cover, 16. Lower limit ring, 17. Solid propellant, 18. Sealing diaphragm. Detailed Implementation

[0018] The following detailed description is provided in conjunction with the accompanying drawings and specific embodiments.

[0019] Example 1 like Figure 1 The liquid rocket engine multiple start-up ignition system shown includes a bracket 1 and a base 12. The bracket 1 is used to position and install all other components. The bracket 1 is fixedly connected to the base 12. A servo motor 2 is fixedly connected to the bracket 1. The output shaft 9 of the servo motor 2 is connected to the first gear 3 and the ignition device in sequence. A firing device is provided on the side of the servo motor 2. The firing device is fixedly connected to the side of the housing of the servo motor 2 through a guide rail 5. The servo motor 2 controls the start, stop and speed of the first gear 3. The first gear 3 controls the firing of the firing device.

[0020] Example 2 like Figure 1The liquid rocket engine multiple start-up ignition system shown includes a bracket 1 and a base 12. The bracket 1 is used to position and install all other components. The bracket 1 is fixedly connected to the base 12. A servo motor 2 is fixedly connected to the bracket 1. The output shaft 9 of the servo motor 2 is connected to the first gear 3 and the ignition device in sequence. A firing device is provided on the side of the servo motor 2. The firing device is fixedly connected to the side of the housing of the servo motor 2 through a guide rail 5. The servo motor 2 controls the start, stop and speed of the first gear 3. The first gear 3 controls the firing of the firing device.

[0021] The ignition device includes an igniter slot 11, which is fixedly connected to the end of the output shaft of the servo motor 2. The igniter slot 11 has a cylindrical structure and is coaxially arranged with the servo motor 2. The igniter slot 11 has six through holes along its axial direction, and these six through holes are evenly arranged around the axis of the igniter slot 11. An igniter 10 is fixed in each through hole. The igniter slot 11 and the base 12 can rotate relative to each other.

[0022] Example 3 The liquid rocket engine multiple start-up ignition system includes a bracket 1 and a base 12. The bracket 1 is used to position and install all other components. The bracket 1 is fixedly connected to the base 12. A servo motor 2 is fixedly connected to the bracket 1. The output shaft 9 of the servo motor 2 is connected to the first gear 3 and the ignition device in sequence. A firing device is provided on the side of the servo motor 2. The firing device is fixedly connected to the side of the housing of the servo motor 2 through a guide rail 5. The servo motor 2 controls the start, stop and speed of the first gear 3. The first gear 3 controls the firing of the firing device.

[0023] like Figure 2 As shown, the ignition device includes an igniter slot 11, which is fixedly connected to the end of the output shaft of the servo motor 2. The igniter slot 11 is a cylindrical structure and is coaxially arranged with the servo motor 2. The igniter slot 11 has three through holes along its axial direction, and these three through holes are evenly arranged around the axis of the igniter slot 11. An igniter 10 is fixed in each through hole.

[0024] Example 4 like Figure 1 The liquid rocket engine multiple start-up ignition system shown includes a bracket 1 and a base 12. The bracket 1 is used to position and install all other components. The bracket 1 is fixedly connected to the base 12. A servo motor 2 is fixedly connected to the bracket 1. The output shaft 9 of the servo motor 2 is connected to the first gear 3 and the ignition device in sequence. A firing device is provided on the side of the servo motor 2. The firing device is fixedly connected to the side of the housing of the servo motor 2 through a guide rail 5. The servo motor 2 controls the start, stop and speed of the first gear 3. The first gear 3 controls the firing of the firing device.

[0025] The ignition device includes an igniter slot 11, which is fixedly connected to the end of the output shaft of the servo motor 2. The igniter slot 11 has a cylindrical structure and is coaxially arranged with the servo motor 2. The igniter slot 11 has six through holes along its axial direction, and these six through holes are evenly arranged around the axis of the igniter slot 11. An igniter 10 is fixed in each through hole. The igniter slot 11 and the base 12 can rotate relative to each other.

[0026] A mounting shaft is fixedly connected to the side of the servo motor 2. The mounting shaft is connected to the second gear 4 of the firing device via a rolling bearing. The second gear 4 meshes perpendicularly with the first gear 3 for transmission. A rotating lever is fixedly connected to the eccentric position on the side of the second gear 4 opposite to the servo motor 2. The guide rail frame 5 is fixedly connected to a guide rail 6 along its length. The firing pin 7 of the firing device is sleeved inside the guide rail 6. A semi-circular groove 8 is fixedly connected to the end of the firing pin 7 near the second gear 4. The semi-circular groove 8 is slidably connected to the rotating lever. The radius of the semi-circular groove 8 is the same as the eccentricity of the rotating lever, both being 0.2 times the root circle radius of the second gear. The first gear 3 and the second gear 4 have the same module. The number of teeth of the first gear 3 is 6 times the number of teeth of the second gear 4. The first gear 3 has 72 teeth, and the second gear 4 has 12 teeth.

[0027] When the servo motor 2 outputs torque, the output shaft 9 drives the first gear 3 and the igniter slot 11 to rotate; the first gear 3 drives the second gear 4 to rotate, and the rotation lever of the second gear 4 controls the striker 7 to move up and down along the guide rail 6.

[0028] Example 5 The liquid rocket engine multiple start-up ignition system includes a bracket 1 and a base 12. The bracket 1 is used to position and install all other components. The bracket 1 is fixedly connected to the base 12. A servo motor 2 is fixedly connected to the bracket 1. The output shaft 9 of the servo motor 2 is connected to the first gear 3 and the ignition device in sequence. A firing device is provided on the side of the servo motor 2. The firing device is fixedly connected to the side of the housing of the servo motor 2 through a guide rail 5. The servo motor 2 controls the start, stop and speed of the first gear 3. The first gear 3 controls the firing of the firing device.

[0029] The ignition device includes an igniter slot 11, which is fixedly connected to the end of the output shaft of the servo motor 2. The igniter slot 11 has a cylindrical structure and is coaxially arranged with the servo motor 2. The igniter slot 11 has three through holes along its axial direction, and these three through holes are evenly arranged around the axis of the igniter slot 11. An igniter 10 is fixed in each through hole. The igniter slot 11 and the base 12 can rotate relative to each other.

[0030] A mounting shaft is fixedly connected to the side of the servo motor 2. The mounting shaft is connected to the second gear 4 of the firing device via a rolling bearing. The second gear 4 meshes perpendicularly with the first gear 3 for transmission. A rotating lever is fixedly connected to the eccentric position on the side of the second gear 4 opposite to the servo motor 2. The guide rail frame 5 is fixedly connected to a guide rail 6 along its length. The firing pin 7 of the firing device is sleeved inside the guide rail 6. A semi-circular groove 8 is fixedly connected to the end of the firing pin 7 near the second gear 4. The semi-circular groove 8 is slidably connected to the rotating lever. The radius of the semi-circular groove 8 is the same as the eccentricity of the rotating lever, both being 0.2 times the root circle radius of the second gear. The first gear 3 and the second gear 4 have the same module. The number of teeth of the first gear 3 is 3 times the number of teeth of the second gear 4. The first gear 3 has 24 teeth, and the second gear 4 has 8 teeth.

[0031] The base 12 has a fuel injection port at the bottom, which is located directly below the firing pin 7. The shape and size of the fuel injection port are the same as the shape and size of the cross-section of the igniter 10. All igniters 10 use the same fuel injection port.

[0032] Example 6 The liquid rocket engine multiple start-up ignition system includes a bracket 1 and a base 12. The bracket 1 is used to position and install all other components. The bracket 1 is fixedly connected to the base 12. A servo motor 2 is fixedly connected to the bracket 1. The output shaft 9 of the servo motor 2 is connected to the first gear 3 and the ignition device in sequence. A firing device is provided on the side of the servo motor 2. The firing device is fixedly connected to the side of the housing of the servo motor 2 through a guide rail 5. The servo motor 2 controls the start, stop and speed of the first gear 3. The first gear 3 controls the firing of the firing device.

[0033] The ignition device includes an igniter slot 11, which is fixedly connected to the end of the output shaft of the servo motor 2. The igniter slot 11 has a cylindrical structure and is coaxially arranged with the servo motor 2. The igniter slot 11 has three through holes along its axial direction, and these three through holes are evenly arranged around the axis of the igniter slot 11. An igniter 10 is fixed in each through hole. The igniter slot 11 and the base 12 can rotate relative to each other.

[0034] A mounting shaft is fixedly connected to the side of the servo motor 2. The mounting shaft is connected to the second gear 4 of the firing device via a rolling bearing. The second gear 4 meshes perpendicularly with the first gear 3 for transmission. A rotating lever is fixedly connected to the eccentric position on the side of the second gear 4 opposite to the servo motor 2. The guide rail frame 5 is fixedly connected to a guide rail 6 along its length. The firing pin 7 of the firing device is sleeved inside the guide rail 6. A semi-circular groove 8 is fixedly connected to the end of the firing pin 7 near the second gear 4. The semi-circular groove 8 is slidably connected to the rotating lever. The radius of the semi-circular groove 8 is the same as the eccentricity of the rotating lever, both being 0.2 times the root circle radius of the second gear. The first gear 3 and the second gear 4 have the same module. The number of teeth of the first gear 3 is 3 times the number of teeth of the second gear 4. The first gear 3 has 24 teeth, and the second gear 4 has 8 teeth.

[0035] The base 12 has a fuel injection port at the bottom, which is located directly below the firing pin 7. The shape and size of the fuel injection port are the same as the shape and size of the cross-section of the igniter 10. All igniters 10 use the same fuel injection port.

[0036] The igniter 10 includes a housing 13 and a cover. The cover is located at the port of the housing 13 near the firing pin 7. The other end of the housing 13 is sealed with a sealing diaphragm 18. A spring is fixedly connected inside the cover. The other end of the spring abuts against the firing cap 15. A solid propellant 17 is filled between the firing cap 15 and the sealing diaphragm 18. The firing cap 15, the sealing diaphragm 18 and the inner wall of the housing 13 together form a sealed space. The solid propellant 17 is a magnesium / polytetrafluoroethylene igniter.

[0037] Solid agent 17 is a magnesium / polytetrafluoroethylene igniter, which is composed of the following components by mass percentage: magnesium powder 55%, polytetrafluoroethylene 40%, and fluororubber 5%.

[0038] The igniter 10 also includes an upper limit ring 14 and a lower limit ring 16, which are fixed inside the housing 13. The firing cap 15 is located between the upper limit ring 14 and the lower limit ring 16. The igniter 10 also includes an upper limit ring 14 and a lower limit ring 16, which are fixed to the inner wall of the housing 13. The upper limit ring 14 is adjacent to the firing cover 15, which is located between the upper limit ring 14 and the lower limit ring 16. The upper limit ring 14 and the lower limit ring 16 are used to constrain the movement path of the firing cover 15.

[0039] Example 7 Based on Example 6, there is a ring-shaped protrusion below the firing cap 15 and a ring-shaped groove above the lower limiting ring 16. The groove is filled with a layer of heat-resistant lubricating granular material, preferably graphite. When the firing cap 15 is fired under pressure, the firing cap 15 continues to move downward until the protrusion is fully inserted into the groove of the lower limiting ring 16. The length of the protrusion is the same as the depth of the groove, but the diameter of the protrusion is slightly smaller than the diameter of the groove. The heat-resistant lubricating particles then become the filler between the protrusion and the groove, completing the structural seal and preventing the backflow of the gas generated by the solid agent 17 from damaging other components.

[0040] The lower limit ring 16 has an annular groove, and the lower end face of the firing cap 15 has a coaxial annular protrusion that matches the annular groove. The annular groove is filled with graphite particles with a particle size of 50μm-100μm, which serve as heat-resistant lubricants. When the firing cap 15 is fired under pressure, it continues to move downward until the annular protrusion is fully inserted into the annular groove of the lower limit ring 16. The length of the annular protrusion is the same as the depth of the annular groove, but the diameter of the protrusion is slightly smaller than the diameter of the groove. At this time, the graphite particles become the filler between the annular protrusion and the annular groove, completing the structural seal and preventing the backflow of the gas generated by the solid agent 17 from damaging other components.

[0041] Working process and principle: The number of igniters 10 in the multiple-start ignition system of the liquid rocket engine is determined according to the ignition frequency requirement of the rocket launch mission. The number of igniters 10 is the same as the number of ignitions required for the rocket launch mission. The gear ratio of the first gear 3 and the second gear 4 of the ignition system is determined based on the number of igniters 10. Determine the eccentricity of the rotating lever on the second gear 4. The eccentricity is greater than the distance between the bottom of the firing pin 7 and the firing cap 15 of the igniter 10, and the eccentricity is selected between 0.2 and 0.8 times the radius of the root circle of the second gear 4.

[0042] After the ignition system parameters are determined, the assembly of the liquid rocket engine's multiple-start ignition system is completed, and the ignition system is installed into the rocket launch system. After the ignition command is transmitted to the liquid rocket engine's multiple-start ignition system, the servo motor 2 drives the output shaft 9 to rotate. The output shaft 9 drives the first gear 3 and the igniter slot 11 to rotate, causing the igniter 10 in the igniter slot 11 to rotate to the fuel injection port. At the same time, the first gear 3 drives the second gear 4 to rotate. The rotating lever on the second gear 4 disc controls the up-and-down movement of the firing pin 7 via the semi-circular slide 8. When the rotating lever moves in the arc section of the semi-circular slide 8, the firing pin 7 will not move up and down, and the bottom of the firing pin 7 will be higher than the plane of the igniter 10, so ignition will not be triggered. When the rotating lever moves in the straight section of the semi-circular slide 8, the firing pin 7 will start to move down rapidly and then rise rapidly. As the firing pin 7 rapidly moves downward and then quickly rises, it strikes the igniter 10, compressing the spring and transmitting the impact to the firing cap 15. The firing cap 15 then compresses the solid propellant 17, which burns under pressure and is ejected from the bottom fuel injection port, completing the first ignition. When subsequent ignition commands are transmitted to the liquid rocket engine's ignition system for multiple starts, the system repeats the above actions to complete ignition until the last igniter ignites.

Claims

1. A liquid rocket engine multiple-start ignition system, characterized in that, Includes a bracket (1) and a base (12). The bracket (1) and the base (12) are fixedly connected. A servo motor (2) is fixedly connected on the bracket (1). The output shaft (9) of the servo motor (2) is connected to the first gear (3) and the ignition device in sequence. A firing device is provided on the side of the servo motor (2). The firing device is fixedly connected to the side of the housing of the servo motor (2) through a guide rail frame (5).

2. The liquid rocket engine multiple-start ignition system according to claim 1, characterized in that... The ignition device includes an igniter slot (11), which is fixedly connected to the end of the output shaft (9) of the servo motor (2). The igniter slot (11) is a cylindrical structure and is coaxially arranged with the servo motor (2). The igniter slot (11) has several through holes along its axial direction, and these through holes are evenly arranged around the axis of the igniter slot (11). An igniter (10) is fixed in each through hole.

3. The liquid rocket engine multiple-start ignition system according to claim 2, characterized in that... The servo motor (2) is fixedly connected to a mounting shaft on its side. The mounting shaft is connected to the second gear (4) of the firing device through a rolling bearing. The second gear (4) meshes perpendicularly with the first gear (3) for transmission. A rotating lever is fixedly connected to the eccentric position on the side of the second gear (4) opposite to the servo motor (2). The guide rail frame (5) is fixedly connected to a guide rail (6) along its length. The firing pin (7) of the firing device is sleeved inside the guide rail (6). A semi-circular groove (8) is fixedly connected to the end of the firing pin (7) near the second gear (4). The semi-circular groove (8) is slidably connected to the rotating lever.

4. The liquid rocket engine multiple-start ignition system according to claim 3, characterized in that... The second gear (4) has the same module as the first gear (3), and the gear ratio of the second gear (4) to the first gear (3) is set according to the following formula: in It is the number of teeth of the first gear (3). It is the number of teeth of the second gear (4). It is the number of igniters (10) set in the igniter slot (11).

5. The liquid rocket engine multiple-start ignition system according to claim 4, characterized in that... The eccentricity of the rotating lever is 0.2-0.8 times the radius of the root circle of the second gear (4), and the radius of the semi-circular groove (8) is the same as the eccentricity of the rotating lever.

6. The liquid rocket engine multiple-start ignition system according to claim 5, characterized in that... The base (12) has a fuel injection port at the bottom, which is located directly below the firing pin (7). The shape and size of the fuel injection port are the same as the shape and size of the cross-section of the igniter (10).

7. The liquid rocket engine multiple-start ignition system according to claim 6, characterized in that... The igniter (10) includes a housing (13) and a cover. The cover is located at the port of the housing (13) near the firing pin (7). The other end of the housing (13) is sealed with a sealing diaphragm (18). A spring is fixedly connected inside the cover. The other end of the spring abuts against the firing cap (15). A solid agent (17) is filled between the firing cap (15) and the sealing diaphragm (18). The firing cap (15), the sealing diaphragm (18), and the inner wall of the housing (13) together form a sealed space. The solid agent (17) is a magnesium / polytetrafluoroethylene igniter.

8. The liquid rocket engine multiple-start ignition system according to claim 7, characterized in that... The igniter (10) also includes an upper limit ring (14) and a lower limit ring (16), which are fixed to the inner wall of the housing (13). The upper limit ring (14) is adjacent to the firing cap (15), which is located between the upper limit ring (14) and the lower limit ring (16).

9. The liquid rocket engine multiple-start ignition system according to claim 8, characterized in that... The lower limit ring (16) has an annular groove, and the lower end face of the firing cap (15) has a coaxial annular protrusion that matches the annular groove. The annular groove is filled with graphite particles with a particle size of 50μm-100μm.

10. A method for multiple ignition starts of a liquid rocket engine, employing the multiple ignition start system for a liquid rocket engine as described in claim 9, characterized in that... The specific steps are as follows: Step 1: Determine the number of igniters (10) that are the same as the number of ignitions required for rocket launch; Step 2: Determine the gear ratio between the first gear (3) and the second gear (4) based on the number of igniters (10). The gear ratio is equal to the number of igniters (10). Step 3: Determine the eccentricity of the rotating lever on the second gear (4). The eccentricity is greater than the distance between the bottom of the firing pin (7) and the firing cap (15) of the igniter (10), and the eccentricity is selected between 0.2 and 0.8 times the radius of the root circle of the second gear (4). Step 4: Complete the assembly of the ignition system and ignite after the ignition command is transmitted to the ignition system.

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