Single-component injector adapted to additive manufacturing and its manufacturing method

Abstract

This invention discloses a monocomponent injector adapted to additive manufacturing and its manufacturing method. The monocomponent injector mainly consists of an upper injection disk, an upper injection disk support structure, a capillary tube, an injector support structure, and a lower injection disk with a second capillary orifice. This invention utilizes the high degree of freedom in the manufacturing process of the monocomponent injector in additive manufacturing, optimizing the design of the monocomponent injector to adapt to additive manufacturing. By increasing the dimensional margin of the monocomponent injector, optimizing the local support structure, increasing the thermal resistance between the upper and lower injection disks, and selecting a suitable printing direction, the invention achieves the ability to manufacture the monocomponent injector at low cost, high reliability, and quickly.

Description

Technical Field

[0001] This invention belongs to the field of liquid engine design and manufacturing, and in particular relates to a single-component injector adapted to additive manufacturing and its design and manufacturing method. Background Technology

[0002] Monopropellant engines are liquid-fueled attitude and orbit control engines widely used in rocket attitude control and long-term satellite operation. The monopropellant injector is a crucial component of a monopropellant engine, playing a vital role in uniformly distributing propellant to the catalyst bed, thereby ensuring stable combustion and high performance. Due to the thermal explosion characteristics of monopropellant propellants, to prevent the high temperatures during engine operation from being transferred to the injector's accumulator cavity, which could lead to an engine explosion during a second restart, causing rocket attitude control failure and significantly reducing satellite lifespan, the monopropellant injector is generally designed as a structure consisting of an upper injector disk, a heat shield (support structure), a capillary tube, and a lower injector disk. This structure isolates heat and improves engine operational safety. The upper injector disk contains a accumulator cavity, which, along with the capillary tube, is responsible for diverting the propellant. The heat shield, while providing structural support, must also possess high thermal resistance. The lower injector disk connects the capillary tube and the heat shield, and also connects to the catalyst bed.

[0003] However, in actual design and manufacturing, dozens of capillary tubes need to be welded simultaneously onto the single-component injector. To ensure uniform propellant distribution, the bending angle and dimensions of each capillary tube must be controlled consistently. The upper and lower injection discs must maintain appropriate parallelism to ensure the engine thrust line is centered. The entire single-component injector has dozens of welds, all of which must be welded in one go. If even one weld fails, the product is scrapped. This requires that the deformation of each capillary tube and the positional accuracy of the upper and lower injection discs be controlled with high precision while ensuring reliable welding.

[0004] The above problems result in the high difficulty of processing single-component injectors, numerous special processes, long production cycles, low yield rates, and high costs, which severely restrict their mass production and low-cost manufacturing capabilities. Summary of the Invention

[0005] The present invention aims to provide a single-component injector adapted to additive manufacturing and its manufacturing method, which reduces welding difficulty, reduces the precision requirements of parts, reduces the manufacturing difficulty of single-component engines, improves yield, reduces production costs, improves operational reliability, and also provides a possibility for mass production.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] Single-component injectors adapted for additive manufacturing include:

[0008] The upper injection plate includes an engine mounting interface, a valve connection interface, a liquid accumulation chamber, and capillary holes. The valve connection interface is located in the inner area of ​​the engine mounting interface, and the liquid accumulation chamber and capillary holes are located in the inner area of ​​the valve connection interface. The blind holes on the end face of the upper injection plate constitute the liquid accumulation chamber, and the openings on the bottom surface of the blind holes constitute the first capillary holes.

[0009] The lower spray plate is arranged parallel and spaced apart from the upper spray plate, and the lower spray plate has a second capillary hole that penetrates the lower spray plate.

[0010] The capillary tubes are arranged symmetrically between the upper and lower injection disks, with the first end of the capillary tube connected to the first capillary hole and the second end of the capillary tube connected to the second capillary hole. The capillary tubes are curved, and the distance from the first end of the capillary tube to the center of symmetry is less than the distance from the second end to the center of symmetry, so that the capillary tubes are distributed on the generatrix of the rotating body whose outer diameter gradually increases from the upper injection disk to the lower injection disk.

[0011] The upper spray plate support structure, multiple upper spray plate support structures are arranged symmetrically between the upper spray plate and the lower spray plate. One end of the upper spray plate support structure is connected to the upper spray plate. The upper spray plate support structure includes a curved surface with the same curvature as the capillary surface (the capillary surface is a cylindrical surface, and the surface of the upper spray plate support structure is also connected to the capillary through a cylindrical surface), and the upper spray plate support structure is connected to the capillary through this curved surface.

[0012] The injector support structure comprises multiple injector support structures arranged symmetrically between the upper and lower injector disks and located on the outside of the upper injector disk support structure. The injector support structure is Y-shaped, with the bifurcated section of the Y-shape connected to the lower injector disk and the main body section of the Y-shape connected to the upper injector disk. The heat transfer area of ​​the bifurcated section is smaller than that of the main body section.

[0013] Furthermore, the multiple injector support structures are independent of each other and are spaced apart without being connected to each other.

[0014] Furthermore, multiple capillaries are distributed on at least two coaxial but different-shaped generatrices of rotation. The capillaries on different generatrices of rotation do not affect each other, thereby increasing the number and distribution density of capillaries without interference.

[0015] Furthermore, the engine mounting interface consists of multiple connecting holes with equal central angles evenly distributed on the same circumference.

[0016] Furthermore, the valve connection interface consists of multiple connection holes with equal central angles evenly distributed on the same circumference.

[0017] Furthermore, the first capillary pores are distributed on at least two concentric circles with different diameters, and the number of first capillary pores on different circles is not equal, while the first capillary pores on the same circle are evenly distributed according to equal central angles.

[0018] Furthermore, the second capillaries are distributed on at least two concentric circles with different diameters, and the number of second capillaries on the different circles is not equal, while the second capillaries on the same circle are evenly distributed according to equal central angles.

[0019] Furthermore, the capillary includes a curved segment and a straight segment, and the capillary is connected to the first capillary pore and the second capillary pore respectively through the straight segment;

[0020] The upper injection disk support structure extends from the tangent at the intersection of the curved and straight segments on the capillary tube toward the upper injection disk.

[0021] Furthermore, the number of nozzle support structures is less than the number of upper nozzle disk support structures. The relatively smaller number of nozzle support structures creates a larger spacing between them, which facilitates capillary cleaning of the inner side after printing, and also reduces the amount of printing material used in conjunction with the upper nozzle disk support structure.

[0022] The manufacturing method of the single-component injector adapted to additive manufacturing, as described above, employs additive manufacturing for printing and includes:

[0023] The end face of the lower injection disk is used as the starting position for additive printing, and the end face of the upper injection disk is used as the ending position for additive printing. The lower injection disk, the injection nozzle support structure, the capillary, the upper injection disk support structure, and the upper injection disk are printed sequentially.

[0024] further,

[0025] The printing thickness of the upper and lower injection disks includes the cutting margin for subsequent machining.

[0026] The ratio of the inner diameter to the wall thickness of the capillary is between 0.5 and 1.0, and the wall thickness of the capillary is greater than or equal to 0.8 mm.

[0027] Small holes are reserved at the engine mounting interface and valve connection interface;

[0028] The length ratio of the Y-shaped bifurcation segment to the main body segment of the injector support structure is 1:1, and the heat transfer area of ​​the bifurcation segment is 0.25 to 0.5 of the heat transfer area of ​​the main body segment.

[0029] The diameter of the first capillary pore is smaller than that of the second capillary pore, and the number and distribution of the first capillary pore are the same as those of the second capillary pore.

[0030] Furthermore, the end face of the lower injection disk, which serves as the starting position for additive printing, includes a ring-shaped protrusion, the inner side of which forms the first capillary printing end face. The thickness of the ring-shaped protrusion serves as a margin for subsequent machining and also as an interface for butt welding with the catalyst bed.

[0031] Compared with existing technologies, this invention discloses a monocomponent injector manufactured using additive manufacturing and its additive manufacturing method. By rationally arranging the structure of the monocomponent injector, applying topology optimization design methods to optimize the local support structure, increasing the thermal resistance between the upper and lower injection disks, and selecting a suitable printing direction, the monocomponent injector is integrally manufactured using additive manufacturing technology. This reduces welding difficulty, lowers the precision requirements of parts, reduces the manufacturing difficulty of the monocomponent engine, improves the yield rate, reduces production costs, and improves operational reliability. It also provides a possible solution for the mass production of monocomponent injectors. Attached Figure Description

[0032] Figure 1 This is a perspective view of the additively manufactured single-component injector of the present invention;

[0033] Figure 2 This is a schematic diagram of a single-component interface using additive manufacturing in this invention;

[0034] In the diagram: 1—Upper injection plate; 2—Upper injection plate support structure; 3—Capillary tube; 4—Injector support structure; 5—Lower injection plate; 6—Engine mounting interface; 7—Valve connection interface; 8—Accumulation chamber and capillary orifice; 9—Second capillary orifice. Detailed Implementation

[0035] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. However, it should not be construed that the scope of the subject matter of the present invention is limited to the following embodiments. All modifications, substitutions and alterations made based on ordinary technical knowledge and common practices in the art without departing from the above-described technical concept of the present invention are included within the scope of the present invention.

[0036] like Figure 1 and Figure 2 As shown, this embodiment presents a single-component injector designed for additive manufacturing, consisting of an upper injector disk 1 with a liquid accumulation chamber and a first capillary orifice, an upper injector disk support structure 2, a capillary tube 3, an injector support structure 4, and a lower injector disk 5 with a second capillary orifice 9.

[0037] In this embodiment, considering the poor surface roughness of products directly generated by additive manufacturing, a thickness is added to the upper injection disk 1 as a margin for subsequent machining. Because the diameters of the upper injection disk 1 and the lower injection disk 5 differ significantly, traditional additive manufacturing requires additional support. However, after fully considering the process characteristics of additive manufacturing and evaluating the printing direction, and taking into account the small capillary aperture, to ensure capillary aperture quality, the lower injection disk 5 is selected as the printing start face, and the upper injection disk 1 as the printing end face. Simultaneously, to avoid printing deformation of the upper injection disk 1, this invention adds a support outside the capillary tube 3, positioned tangentially to the vertical section of the capillary tube 3 (in additive manufacturing, the vertical direction ensures the best product quality during printing; therefore, to reduce the deformation of the injector during manufacturing, a tangential position to the vertical section of the capillary tube 3 is chosen), extending to the upper injection disk 1. To ensure the smoothness of the inner diameter of capillary tube 3 and the structural strength, so as to ensure the uniform flow of propellant in the injector, the ratio of the inner diameter to the wall thickness of capillary tube 3 is controlled at around 0.5 to 1.0.

[0038] Considering the poor quality of threaded hole generation in additive manufacturing, the interface of the single-component injector is designed with a small hole of φ1mm to φ2mm reserved at the location where threaded holes are required, allowing for post-processing dimensions.

[0039] For the injector support structure 4, in order to maximize thermal resistance and reduce weight, four "Y"-shaped tree branch structures are used as supports. The main trunk of the tree branch starts from the upper injection plate 1, and two branches start to branch out at a height of about 1 / 2 between the upper injection plate 1 and the lower injection plate 5, which improves the working safety and reliability of the injector.

[0040] The lower spray plate 5 has increased thickness to allow for post-processing dimensions, and the second capillary hole 9 is designed in the same direction as the first capillary hole on the upper spray plate 1. The size of the second capillary hole 9 can be adaptively increased according to the size of the lower spray plate 5.

[0041] Using the above design and manufacturing methods, a single-component injector suitable for additive manufacturing can be designed and manufactured, giving it low cost, rapid manufacturing capability, and high reliability.

[0042] like Figure 2 As shown in the left-middle figure, the upper injection plate 1 has three areas: the engine mounting interface 6 has four circumferentially distributed connecting holes; the valve connection interface 7 has six circumferentially distributed connecting holes; and the liquid accumulation chamber and capillary pores 8 are centered, containing two rings of first capillary pores: four circumferentially distributed in the inner ring and twelve circumferentially distributed in the outer ring. The engine mounting interface 6 and the valve connection interface 7 have pre-reserved φ1mm holes for later hole enlargement and positioning. All holes are... Figure 2 The top two sections are symmetrical on both the left and right.

[0043] The upper injection disk support structure 2 is tangent to the vertical section of the outer wall of the capillary tube 3, totaling 12 pieces, extending upwards along the capillary tube 3 to the upper injection disk 1 to ensure that the upper injection disk 1 remains flat and unbiased during printing. The capillary tube 3 protrudes outwards circumferentially (through a curved section), presenting a "birdcage" shape, and the wall thickness of the capillary tube 3 is not less than 0.8mm, to ensure that the capillary tube 3 conforms to the basic principle of additive manufacturing printers and meets structural requirements. The "birdcage" shape facilitates spatial layout and increases the length of the capillary tube 3, which is beneficial to improving the heat insulation effect of the injector. Figure 1 The capillary tubes 3 are distributed in two ways. Four of them are without the upper injection plate support structure 2. The outer diameter of the cross section of the rotating body where these four capillary tubes 3 are located has a relatively small trend (i.e., the curvature of the curve segment is smaller and closer to a straight line). The other 12 are equipped with the upper injection plate support structure 2. The outer diameter of the cross section of the rotating body where these 12 capillary tubes 3 are located has a relatively larger trend (i.e., the curvature of the curve segment is larger and more curved).

[0044] The injector support structure 4 is topologically optimized through the coupling of structural stress and heat transfer. It adopts four "Y"-shaped tree fork structures as supports. The main trunk of the tree fork starts from the upper injection plate 1 and branches into two "tree forks" at about 1 / 2 of the height. The heat transfer area of ​​the "tree fork" is about 0.25 to 0.5 times that of the "tree trunk". This reduces the heat transferred from the lower injection plate 5 to the upper injection plate 1, avoids excessive temperature in the liquid accumulation chamber that may cause thermal explosion of the propellant, and improves the working safety and reliability of the injector.

[0045] like Figure 2 As shown in the middle right figure, the lower spray plate 5 is connected to the capillary tube 3 and the sprayer support structure 4. Its lower end face has two rings of second capillary holes 9, four in the inner ring and twelve in the outer ring, evenly distributed in a crisscross pattern. The hole diameter is the same as the first capillary hole of the upper spray plate 1, and their positions and orientations are the same. Figure 2 The top left and right sides are symmetrical.

[0046] By arranging the interface of the upper injection plate 1 and the distribution of the first capillary in the liquid accumulation chamber, increasing the upper injection plate support structure 2, optimizing the injector support structure 4, and selecting a reasonable additive manufacturing direction, a single-component injector adapted to additive manufacturing can be realized.

[0047] The above are the main concepts of the invention. All single-component injectors and manufacturing methods designed based on the concepts of this invention fall within the protection scope of this invention.

Claims

1. A single-component injection nozzle adapted for additive manufacturing, characterized in that, include: The upper injection plate (1) includes an engine fixing interface (6), a valve connection interface (7), and a liquid accumulation chamber and a capillary (8). The valve connection interface (7) is located in the inner area of ​​the engine fixing interface (6), and the liquid accumulation chamber and the capillary (8) are located in the inner area of ​​the valve connection interface (7). The blind hole on the end face of the upper injection plate (1) constitutes the liquid accumulation chamber, and the through hole opened on the bottom surface of the blind hole constitutes the first capillary. The lower spray plate (5) is arranged parallel to the upper spray plate (1) at intervals. The lower spray plate (5) has a second capillary hole (9) that penetrates the lower spray plate (5). Capillary tubes (3), multiple capillary tubes (3) are arranged symmetrically between the upper injection plate (1) and the lower injection plate (5) according to the center, and the first end of the capillary tube (3) is connected to the first capillary hole, and the second end of the capillary tube (3) is connected to the second capillary hole (9). The capillary tube (3) is curved, wherein the distance from the first end of the capillary tube (3) to the center of symmetry is less than the distance from the second end to the center of symmetry, so that the capillary tubes (3) are distributed on the generatrix of the rotating body whose outer diameter gradually increases from the upper injection plate (1) to the lower injection plate (5); The upper spray plate support structure (2) is arranged symmetrically between the upper spray plate (1) and the lower spray plate (5). One end of the upper spray plate support structure (2) is connected to the upper spray plate (1). The upper spray plate support structure (2) includes a curved surface with the same curvature as the surface of the capillary tube (3), and the upper spray plate support structure (2) is connected to the capillary tube (3) through the curved surface. The injector support structure (4) is arranged symmetrically between the upper injector plate (1) and the lower injector plate (5) and located outside the upper injector plate support structure (2). The injector support structure (4) is Y-shaped. The bifurcated section of the Y-shape is connected to the lower injector plate (5), and the main body section of the Y-shape is connected to the upper injector plate (1). The heat transfer area of ​​the bifurcated section is smaller than the heat transfer area of ​​the main body section.

2. The single-component injection nozzle adapted for additive manufacturing according to claim 1, characterized in that: The engine mounting interface (6) consists of multiple connecting holes with equal central angles evenly distributed on the same circumference.

3. The single-component injection nozzle adapted for additive manufacturing according to claim 1, characterized in that: The valve connection interface (7) consists of multiple connection holes with equal central angles evenly distributed on the same circumference.

4. The single-component injector adapted for additive manufacturing according to claim 1, characterized in that: The first capillary pores are distributed on at least two concentric circles with different diameters, and the number of first capillary pores on different circles is not equal. The first capillary pores on the same circle are evenly distributed according to equal central angles.

5. The single-component injection nozzle adapted for additive manufacturing according to claim 1, characterized in that: The second capillary pores (9) are distributed on at least two concentric circles with different diameters, and the number of second capillary pores (9) on different circles is not equal. The second capillary pores (9) on the same circle are evenly distributed according to equal central angles.

6. The single-component injector adapted for additive manufacturing according to claim 1, characterized in that: The capillary (3) includes a curved segment and a straight segment, and the capillary (3) is connected to the first capillary pore and the second capillary pore (9) respectively through the straight segment; The upper injection disk support structure (2) extends from the tangent at the intersection of the curved and straight segments on the capillary (3) toward the upper injection disk (1).

7. The single-component injection nozzle adapted for additive manufacturing according to claim 1, characterized in that: The number of injector support structures (4) is less than the number of upper injection disc support structures (2).

8. The method for manufacturing a single-component injector adapted for additive manufacturing as described in claim 1, characterized in that, It is printed using additive manufacturing and includes: The end face of the lower injection disk (5) is used as the starting position for additive printing, and the end face of the upper injection disk (1) is used as the ending position for additive printing. The printing of the lower injection disk (5), the injection support structure (4), the capillary (3), the upper injection disk support structure (2) and the upper injection disk (1) are completed in sequence.

9. The manufacturing method according to claim 8, characterized in that: The printing thickness of the upper injection disk (1) and the lower injection disk (5) includes the cutting margin for subsequent machining; The ratio of the inner diameter to the wall thickness of the capillary (3) is between 0.5 and 1.0, and the wall thickness of the capillary (3) is greater than or equal to 0.8 mm. Small holes are reserved at the engine fixing interface (6) and valve connection interface (7); The length ratio of the Y-shaped bifurcation segment to the main body segment of the injector support structure (4) is 1:1, and the heat transfer area of ​​the bifurcation segment is 0.25 to 0.5 of the heat transfer area of ​​the main body segment. The diameter of the first capillary pore is smaller than that of the second capillary pore (9), and the number and distribution of the first capillary pore are the same as those of the second capillary pore (9).

10. The manufacturing method according to claim 8, characterized in that: The end face of the lower injection disk (5), which serves as the starting position for additive printing, includes a ring of annular protrusions, and the inner side of the inner ring of the annular protrusions is the first capillary printing end face.

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