A solid rocket engine tail nozzle offset shell structure

Abstract

The present application relates to the field of solid rocket engine casing structures, specifically disclosing a solid rocket engine tail nozzle offset casing structure, comprising an internally connected combustion chamber casing, a tail pipe casing, and a front head casing. The tail pipe casing and the front head casing are respectively connected to the two ends of the combustion chamber casing, and the axis of the tail pipe casing is parallel to, but not overlapping with, the axis of the combustion chamber casing. Under conditions where the radial dimensions of a missile are strictly limited, the present invention effectively utilizes existing space, adopts a tail pipe offset casing design structure, and utilizes the offset torque generated by this structure during engine operation to effectively solve the problem of missile flight instability and improve missile flight reliability. The combustion chamber casing adopts a large opening design, which, while ensuring the convenience of engine charge, connects the front head casing and the combustion chamber casing with pins, effectively solving the problems of complex processing, high threaded hole precision requirements, and complex assembly and disassembly associated with bolt connections, while also improving the engine's loading coefficient and total stroke.

Description

Technical Field

[0001] The invention relates to a solid rocket engine casing design structure, and in particular to a solid rocket engine tail nozzle offset casing structure. Background Art

[0002] The solid rocket motor case structure is a crucial component of missile engines and a key component of the engine structure. It serves as the tank for solid propellant, the site where propellant combustion generates thrust, and an integral part of the missile body, bearing the missile's loads while also providing support and connections for the missile's external interfaces. While meeting the engine development mission requirements issued by the missile's overall management, the design of the motor case structure should fully consider the various loads and torque requirements during missile flight, ensuring the missile remains stable and controlled throughout its flight, thereby improving its overall flight reliability.

[0003] An existing missile adopts an internally embedded launch overall design, which strictly limits the radial dimensions of the missile. At the same time, the missile's center of mass deviation caused by the overall design of the missile poses a risk of loss of control during flight. If a traditional engine casing structure design is adopted, it cannot meet the overall requirements and cannot solve the problem of missile flight reliability. Summary of the Invention

[0004] To address the aforementioned issues, this application provides a solid rocket motor tail nozzle offset casing structure. To more effectively utilize existing space within the context of strictly limited missile radial dimensions, this design employs a tail nozzle offset solid rocket motor casing structure. The offset torque generated by this design during operation effectively addresses the flight instability caused by the missile's center of mass offset, thereby improving the missile's flight reliability. Furthermore, the combustion chamber casing utilizes a large opening, facilitating convenient charge loading. The pin connection between the front head casing and the combustion chamber casing effectively addresses the complex machining associated with bolted connections, the high overall precision requirements for circumferentially distributed threaded holes, and the complex assembly and disassembly process. This design also improves the engine's loading coefficient and overall engine impulse.

[0005] This application adopts the following technical solutions:

[0006] A solid rocket engine tail nozzle offset casing structure includes an internally connected combustion chamber casing, a tail pipe casing, and a front head casing. The tail pipe casing and the front head casing are respectively connected to the two ends of the combustion chamber casing, and the axis of the tail pipe casing is parallel to but does not overlap with the axis of the combustion chamber casing.

[0007] The combustion chamber shell adopts a structural form of a large front opening and a small offset rear opening, and the rear opening is designed for an internal thread for connection.

[0008] Furthermore, the combustion chamber housing has an outer diameter of Φ300±0.2mm, a front-to-back butt-joint distance of 726±0.2mm, and a wall thickness of 1.8mm. The front butt-joint surface features 45 Φ12 through-holes evenly spaced circumferentially for pinned connection to the front head housing. The combustion chamber housing is thickened to 6mm at the pin-removal point on the front butt-joint surface, consistent with the design requirements for equal strength. The sealing surface at the front opening of the combustion chamber housing is designed to have a thickness of 7mm, a length of 13.3mm, and an inner diameter of Φ286mm. Based on overall connection requirements, connection ports and external connection interfaces are designed on the midsection and rear end surfaces of the combustion chamber housing.

[0009] Furthermore, the design diameter of the rear opening of the combustion chamber shell is The median diameter is The major diameter is The small opening thread structure is used to connect with the tail pipe housing. The thread length is 12mm, the outer circle diameter of the thread is 190mm, and the center axis of the small opening is offset by 35mm relative to the center axis of the combustion chamber housing.

[0010] Furthermore, the axial length of the tail pipe shell is 194mm. The convergent section of the tail pipe shell is designed with a variable thickness from 2.5mm to 11.5mm according to the structural strength requirements of the shell under pressure and load. The front section of the tail pipe shell is designed with an O-ring sealing groove with a width of 4.6mm and a height of 2.75mm. The front and rear interfaces of the tail pipe shell are both designed with external threads. The effective external thread length of the front interface is 16mm, and the thread diameter is 2.6mm. The median diameter is The major diameter is The effective thread length of the rear interface external thread is 15mm, and the thread diameter is The median diameter is The major diameter is

[0011] Furthermore, the axial length of the front head shell is 99mm, and it adopts a butterfly-shaped equal wall thickness design with a designed wall thickness of 2mm. The middle part of the head is designed with an M50×2 open internal thread for connection with external interfaces such as the igniter. According to the axial connection requirements, 45 Ф12 through holes are evenly arranged along the circumference on the top of the front head for connection with the combustion chamber shell, and an O-ring sealing groove is designed according to the sealing requirements. The sealing groove width is 6mm and the height is 3.5mm. At the same time, according to the overall requirements of the missile, connection interface 2 and connection interface 4 are designed on the outer circle and inner side of the front head respectively for connection and fixation of the engine compartment and the missile.

[0012] Furthermore, the pin has a diameter of 12 mm and a height of 11 mm. An M4×1 threaded hole is located in the center of the pin for easy removal when necessary. The pin primarily serves to connect the front head to the shell. The wrapping tape is 0.7 mm thick and 16 mm wide. The wrapping tape is a thin-walled radial binding structural component. Its primary function is to tighten the radial pin and prevent it from slipping out of the pin hole under harsh mechanical conditions.

[0013] In summary, this application has at least the following beneficial technical effects:

[0014] (1) Under the condition that the radial dimensions of the missile are strictly limited, the present invention effectively utilizes the existing space and adopts a tail pipe offset housing design structure. The offset torque generated by this structure when the engine is working effectively solves the problem of missile flight instability and improves the missile flight reliability.

[0015] (2) The combustion chamber shell adopts a large opening design. While ensuring the convenience of engine charging, the front head shell and the combustion chamber shell are connected by pins, which effectively solves the problems of complex processing, high precision requirements for threaded holes, and complex assembly and disassembly existing in bolt connections, and also improves the engine's loading coefficient and total stroke. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 A schematic diagram of the design structure of a tail pipe offset solid rocket motor casing provided in an embodiment of the present application.

[0017] Explanation of the accompanying reference numerals: 1. combustion chamber casing; 2. tail pipe casing; 3. front head casing; 4. pin; 5. wrapping tape. DETAILED DESCRIPTION

[0018] The present application is further described in detail below with reference to the accompanying drawings and specific embodiments:

[0019] The present application discloses a solid rocket engine tail nozzle offset shell structure, such as Figure 1 As shown, the system comprises an internally connected combustion chamber housing, a tail pipe housing, and a front head housing. The tail pipe housing and front head housing are connected to the combustion chamber housing at either end, with the axis of the tail pipe housing parallel to, but not overlapping, the axis of the combustion chamber housing. This offset design between the tail pipe housing and the combustion chamber housing, and the offset torque generated by this design during operation of the solid rocket motor, effectively resolves the flight instability problem caused by the missile's center of mass shift, achieving stable control of the missile.

[0020] The rear docking surface of the front head shell is inserted into the front docking surface of the combustion chamber shell. A connection hole is provided in the portion of the front head shell that lies within the combustion chamber shell. A pin is installed between the combustion chamber shell and the front head shell. The pin passes through the combustion chamber shell and is inserted into the connection hole. The combustion chamber shell is bound with a tape at the pin connection, covering the end of the pin. The pin is a radially tightening pin, and the tape is a thin-walled radial binding structure.

[0021] The combustion chamber shell adopts a structure with a large front opening and a small offset rear opening. The small rear opening is designed to connect with the tail pipe shell 2, and the large front opening is designed to connect with the front head shell 3, and is fixed with pins 4 and wrapping tape 5.

[0022] The outer diameter of the combustion chamber shell 1 is Φ300±0.2mm, the distance between the front and rear docking surfaces is 700±0.2mm, the wall thickness is 1.8mm, and 45 Φ12 through holes are evenly arranged along the circumference of the front docking surface for connection with the front head shell with pins. The wall thickness is thickened to 6mm at the pin arrangement position of the front docking surface according to the equal strength design requirements. The design thickness of the sealing surface of the front large opening of the combustion chamber shell is 7mm, the length of the sealing surface is 13.3mm, and the inner diameter of the sealing surface is Φ286mm. According to the overall connection requirements, the middle section and rear end face of the combustion chamber shell are designed for connection interface 1 and connection interface 3 for external connection.

[0023] The design diameter of the rear opening of the combustion chamber shell 1 is The median diameter is The major diameter is The small opening thread structure is used to connect with the tail pipe housing. The thread length is 12mm, the outer circle diameter of the thread is 190mm, and the center axis of the small opening is offset by 35mm relative to the center axis of the combustion chamber housing.

[0024] The axial length of the tail pipe shell 2 is 194mm. The conical part of the tail pipe shell is the convergent section. The convergent section is designed with a variable thickness from 2.5mm to 11.5mm according to the structural strength requirements of the shell under pressure and load. The front and rear interfaces of the tail pipe shell are both designed with external threads. The effective thread length of the front interface is 16mm, and the thread diameter is 2.5mm. The median diameter is The major diameter is The effective thread length of the rear interface external thread is 15mm, and the thread diameter is The median diameter is The major diameter is Specifically, the front interface of the tail pipe housing is threadedly connected to the combustion chamber housing. The rear end of the combustion chamber housing is provided with a first connection portion, the inner wall of which is provided with an internal threaded section. The front end of the tail pipe housing is provided with a second connection portion, with external threads provided on the outer circumference of the second connection portion. The second connection portion is threadedly connected to the first connection portion. The front end of the tail pipe housing is designed with an O-ring sealing groove with a width of 4.6mm and a height of 2.75mm. Specifically, the tail pipe housing is provided with a sealing portion located at the front end of the first connection portion. The outer circumference of the sealing portion is provided with a sealing groove for accommodating an O-ring, thereby achieving a seal between the sealing portion and the combustion chamber housing.

[0025] The front head shell 3 has an axial length of 99mm and adopts a butterfly-shaped constant wall thickness design with a designed wall thickness of 2mm. The center of the head features an M50×2 open internal thread for connection to external interfaces such as the igniter. To meet axial connection requirements, 45 Ø12 through-holes are evenly distributed along the circumference of the top of the front head for connection to the combustion chamber housing. A sealing groove is defined in the outer wall of the end of the front head shell that inserts into the combustion chamber housing. An O-ring is positioned within the groove, measuring 6mm wide and 3.5mm high. Furthermore, according to the overall requirements of the missile, connection interfaces 2 and 4 are designed on the outer and inner sides of the front head, respectively, for connecting and securing the engine compartment to the missile.

[0026] The pin 4 has a diameter of Ф12mm and a height of 11mm. An M4×1 threaded hole is designed in the middle of the pin for removing the pin when necessary. The main function of the pin 4 is to connect the front head and the shell; the wrapping tape 5 has a thickness of 0.7mm and a width of 16mm. Its main function is to tighten the radial pin 4 to prevent the pin from slipping out of the pin hole under harsh mechanical environment conditions.

[0027] The front head shell material is 30Cr3SiNiMoVA ultra-high strength steel, the pin material is 30CrMnSiA alloy steel, and the strap material is 30CrMnSiA alloy steel.

[0028] Based on the overall mechanical coordination diagram, the specific structural dimensions of the combustion chamber housings 1 and 3, which serve as the external interfaces of the front head housing, were determined. According to the process specifications, the combustion chamber housing 1 was formed by spin welding, while the tail pipe housing 2 and the front head housing 3 were respectively formed by die cutting and CNC machining. To meet the overall docking requirements and to more effectively utilize the available space within the strictly limited radial dimensions of the missile, a tail pipe offset solid rocket motor housing design was adopted. The offset torque generated by this design during operation effectively resolves the missile's flight instability and improves its flight reliability. The combustion chamber housing adopts a large opening design, which not only ensures convenient engine charging, but also utilizes a pin connection between the front head housing and the combustion chamber housing. This effectively solves the problems of bolt connection, such as the complex machining process, high overall precision requirements for circumferentially distributed threaded holes, and complex assembly and disassembly. It also improves the engine's loading coefficient and total engine impulse. The above embodiments are merely illustrative of the present invention. In addition to the above embodiments, the present invention also has other embodiments. All technical solutions formed by equivalent substitution or equivalent modification fall within the scope of protection of the present invention.

Claims

1. A solid rocket motor tail nozzle offset shell structure, characterized by: The invention comprises a combustion chamber casing (1), a tail pipe casing (2) and a front head casing (3) which are connected to each other internally, wherein the tail pipe casing (2) and the front head casing (3) are respectively connected to the two ends of the combustion chamber casing (1), and the axis of the tail pipe casing (2) is parallel to but not coincident with the axis of the combustion chamber casing (1); the combustion chamber casing (1) is filled with solid propellant; and the bias torque generated when the solid rocket engine is in operation.

2. The solid rocket motor tail nozzle offset shell structure according to claim 1, characterized in that: The combustion chamber housing (1) and the tail pipe housing (2) are connected via threads.

3. The solid rocket motor tail nozzle offset casing structure according to claim 2, characterized in that: The rear end of the combustion chamber housing (1) is provided with a first connecting portion, which is designed with an internal thread; the front end of the tail pipe housing (2) is provided with a second connecting portion, which is designed with an external thread; the second connecting portion is connected to the first connecting portion via threads.

4. The solid rocket motor tail nozzle offset casing structure according to claim 1, characterized in that: The rear butt joint surface of the front head shell (3) is inserted into the front butt joint surface of the combustion chamber shell (1).

5. The solid rocket motor tail nozzle offset casing structure according to claim 4, characterized in that: The butt joint surfaces of the front head shell (3) and the combustion chamber shell (1) are respectively provided with connection holes, and the pins (4) pass through the connection holes between the combustion chamber shell (1) and the front head shell (3) to axially fix and limit the combustion chamber shell (1) and the front head shell (3).

6. The solid rocket motor tail nozzle offset casing structure according to claim 5, characterized in that: The combustion chamber housing (1) is provided with a wrapping band (5) at the location of the pin (4); the wrapping band (5) covers the end of the pin (4) and radially limits the pin (4).

7. The solid rocket motor tail nozzle offset casing structure according to claim 5, characterized in that: The pin (4) is a radial fastening pin (4) and plays an axial fixing and limiting role.

8. The solid rocket motor tail nozzle offset casing structure according to claim 6, characterized in that: The wrapping belt (5) is a thin-wall radial binding structure, which plays a radial limiting role on the pin (4).

9. The solid rocket motor tail nozzle offset casing structure according to claim 4, characterized in that: A sealing groove is provided on the outer wall of the butt joint surface between the front head shell (3) and the combustion chamber shell (1), and an O-ring is provided in the sealing groove, thereby achieving radial sealing between the front head shell (3) and the combustion chamber shell (1).

10. The solid rocket motor tail nozzle offset casing structure according to claim 1, characterized in that: The material of the front head shell (3) is 30Cr3SiNiMoVA ultra-high strength steel, the material of the pin (4) is 30CrMnSiA alloy steel, and the material of the wrapping band (5) is 30CrMnSiA alloy steel.

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