Small solid engine tail pressure measuring structure suitable for long-time working

Abstract

The invention discloses a small solid engine tail pressure measuring structure suitable for long-time working. The small solid engine tail pressure measuring structure comprises a variable cross-section pressure measuring hole channel, a red copper sealing gasket, a pressure measuring hole seat and a plug. The pressure measuring hole base is welded to the spray pipe metal shell, the pressure measuring hole corresponds to the pressure measuring channel with the non-metal section, the red copper sealing gasket is arranged in a groove of the pressure measuring hole base, the plug is provided with a trapezoid step, and when tightening torque is applied, the red copper sealing gasket is locally compressed and deformed to achieve sealing. The structure of the pressure measuring hole is greatly reduced, and more choices are provided on the solid engine; the improved design of the pressure measuring hole channel can adapt to pressure measurement of the tail of the engine jet pipe working for a long time; by adjusting the sealing mode and the fixing mode, the sealing reliability is not sacrificed while the pressure measuring structure is greatly reduced.

Description

Technical Field

[0001] This invention relates to the field of solid rocket motor testing technology, and specifically to a pressure measurement structure for the tail section of a small solid rocket motor suitable for long-term operation. Background Technology

[0002] Solid fuel engine pressure testing typically employs a threaded copper gasket sealing structure. Applying a torque to the threads compresses the copper gasket, deforming it and achieving an effective seal at the connection. To ensure reliable sealing at the pressure testing point, the pressure testing port is usually designed with a large thread size to match a large copper gasket. To ensure effective pressure data acquisition, the pressure testing port channel should have a sufficient area and be positioned where combustion gases are unlikely to clog, typically at the engine head. For larger engines, pressure testing port design is not limited by space constraints, and conventional designs can meet the requirements. However, for smaller engines, especially those where the pressure testing port can only be located at the rear and operates for extended periods, conventional structures often fail to meet space requirements.

[0003] Existing solid rocket motor pressure testing structures typically consist of a plug, a copper gasket, and a pressure testing port channel. The plug has a trapezoidal step (inherent to the plug or pressure sensor), and the copper gasket undergoes localized compression deformation when tightened, achieving a seal. When placing the copper gasket, a certain amount of grease is usually applied to both sides to enhance sealing performance and to fix the gasket, ensuring that the installation position remains coaxial with the pressure testing port channel. Patent CN 106762229 A describes an anti-clogging pressure testing structure for a dual-pulse missile engine. This patent describes a bent pressure testing port channel to prevent blockage by particulate matter, ensuring the stability of the testing process. The pressure testing port specifications are M10×1.25, the pressure testing port channel is φ3, and the channel bending angle is 120°. This technical solution uses a bent tube structure for the pressure testing port, which has a relatively complex forming process and is slightly large.

[0004] The disadvantages of existing technologies are: large size, occupying more space, and not suitable for pressure testing at the rear of small engines; if the pressure testing hole channel is too large, the heat transfer will increase if the working time is long, especially when testing at the rear, affecting the reliability of operation; if the pressure testing hole channel is too small, engine residue is prone to clogging the channel when testing at the rear, affecting the stability of pressure testing; the copper sealing gasket has no circumferential limiting design, and it is not easy to ensure concentricity during the process, affecting the sealing reliability. Summary of the Invention

[0005] To address the aforementioned shortcomings, the present invention aims to provide a pressure measurement structure suitable for the tail section of a small engine that operates for extended periods. This structure is miniaturized by improving the design of the pressure measurement port channel, adjusting the compression deformation method of the copper gasket, and adopting a circumferential limiting design for the gasket, thereby meeting the requirements for pressure measurement at the tail section of a small engine that operates for extended periods.

[0006] To address the aforementioned technical problems, one objective of this invention is to provide a pressure measurement structure for the tail section of a small solid rocket motor suitable for long-term operation. The structure includes a non-metallic variable cross-section pressure measurement channel 1, a pressure measurement port seat 2, a copper sealing gasket 3, a pressure measurement port 4, and a plug 5. The pressure measurement port seat 2 is welded to the nozzle's metal housing. The pressure measurement port 4 corresponds to the non-metallic cross-section pressure measurement channel 1. The copper sealing gasket 3 is placed in the groove of the pressure measurement port seat. The plug 5 has a trapezoidal step. When a tightening torque is applied, the copper sealing gasket undergoes local compression deformation to achieve a seal.

[0007] Furthermore, the non-metallic variable cross-section pressure measuring channel has an inlet conical structure, reducing the risk of engine ejection debris clogging the channel.

[0008] Furthermore, the outer diameter of the copper sealing gasket is determined based on the minor diameter of the thread in the pressure testing hole, and the gap between the outer diameter and the minor diameter is 0.3mm~0.5mm, which is sufficient to meet the requirements for gasket replacement after airtightness testing.

[0009] Furthermore, the inner diameter of the sealing gasket should be slightly larger than the inner diameter of the pressure testing hole channel.

[0010] Furthermore, the thickness of the sealing gasket is 1.8mm~2.0mm; the hardness of the copper sealing gasket is (30~35)HB, and the surface finish of the copper gasket is not lower than Ra6.3.

[0011] Furthermore, the pressure measuring hole seat (2) is installed in the groove at the 0.5mm countersunk hole of the nozzle metal shell, and the groove is welded around.

[0012] The above-mentioned one or more technical solutions of the present invention have at least one or more of the following technical effects: the pressure measuring hole structure of the present invention is greatly reduced, providing more options for its arrangement on solid rocket motors; the improved design of the pressure measuring hole channel can adapt to pressure measurement at the tail of the engine nozzle during long-term operation; by adjusting the sealing and fixing methods, the pressure measuring structure is greatly reduced without sacrificing sealing reliability. Attached Figure Description

[0013] Figure 1 Small pressure testing hole structure and tail arrangement; Figure 2 Small pressure testing hole forming process; Wherein: 1-nozzle housing, 2-copper sealing ring, 3-top cover insulation, 4-pressure measuring hole channel, 5-plug, φ2-inner diameter of copper sealing gasket, φ1.5-airflow channel of pressure measuring hole, φ4-inlet size of nozzle inner wall. Detailed Implementation

[0014] This invention provides a pressure measurement structure for the tail section of a small solid rocket motor suitable for long-term operation, comprising four parts: a variable cross-section pressure measurement port channel, a copper sealing gasket, a pressure measurement port seat, and a plug; it presents a sealing method for the small pressure measurement structure, where the compression method of the copper gasket after miniaturization is integral deformation instead of the traditional layout compression deformation; it provides a structural design for the variable cross-section pressure measurement port channel to ensure the reliability of thermal protection at the interface during long-term pressure measurement, while preventing the pressure measurement channel from being blocked by flying objects from the tail section; it provides a method for fixing the position of the small copper sealing gasket to prevent the copper gasket from becoming skewed due to compression deformation, which would affect the sealing reliability; and it provides a molding process for the pressure measurement fixing seat, reducing the difficulty of the molding process.

[0015] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments and accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments obtained. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention are within the scope of protection of the present invention.

[0016] This invention designs a pressure measurement structure for the tail section of a small solid rocket motor suitable for long-term operation. The small pressure measurement orifice structure is arranged on the nozzle convergence surface, such as... Figure 1 As shown, the specific technical solution is explained below: Pressure test port channel: Designed with an inlet conical structure, it effectively reduces the risk of engine ejection debris clogging the channel. The diameter of the pressure test port channel is designed to be as small as possible to improve the thermal insulation reliability of the pressure test area. Furthermore, the reduced diameter of the pressure test port channel corresponds to a smaller inner diameter of the copper gasket, increasing the compression area of ​​the copper gasket and improving sealing reliability. The pressure test port seat is machined from a single piece of metal material, allowing for adaptive size adjustments based on actual conditions. The inner side of the pressure test port seat is machined with threads for easy installation. The depth of the thread relief groove on the pressure test port seat is slightly greater than the thickness of the copper gasket. The pressure test port seat is welded to the nozzle metal housing. The machined pressure test port seat is installed in the groove at the 0.5mm countersunk hole in the nozzle metal housing, and the groove is then welded around its perimeter. Figure 2 As shown.

[0017] Copper gasket: The outer diameter of the copper gasket is determined based on the minor diameter of the pressure test hole thread. A gap of 0.3mm~0.5mm between the outer diameter and the minor diameter of the thread is sufficient to meet the requirements for gasket replacement after airtightness testing. The inner diameter of the gasket should be slightly larger than the inner diameter of the minor channel of the pressure test hole. The recommended gasket thickness is 1.8mm~2.0mm; the hardness of the copper gasket is determined based on the gasket size, and (30~35) HB is recommended. The surface finish of the copper gasket is recommended to be no less than Ra6.3 grade. Pressure test hole plug (pressure sensor interface): The compression copper gasket sealing gasket part is designed as a plane with a surface finish of not less than Ra6.3 grade; Pressure gauge seat forming process: To reduce the difficulty of forming the pressure gauge, it is recommended to machine the pressure gauge seat separately, with the thread relief groove depth slightly greater than the thickness of the copper sealing gasket; machine a countersunk hole of a certain depth at the pressure gauge installation location on the nozzle, and then machine a positioning hole for fixing the copper sealing gasket. The positioning hole depth is recommended to be 0.5mm. The pressure gauge and the nozzle metal shell are welded at the countersunk hole (see...). Figure 2 ).

[0018] A pressure measurement structure for the tail section of a small solid rocket motor suitable for long-term operation is described below: First, during the nozzle production stage, it is necessary to form the pressure measuring hole channel and form the copper sealing gasket groove and pressure measuring hole seat groove on the shell surface, each with a depth of 0.5mm. The specific dimensions are adjusted according to the dimensions of the copper sealing gasket and pressure measuring hole seat groove. Secondly, to reduce the difficulty of forming the pressure test hole seat, it is recommended that it be formed separately using an integrated machining process. The material should be selected according to the actual situation, and the depth of the thread relief groove should be slightly greater than the thickness of the copper sealing gasket. Next, the formed pressure measuring hole seat is installed on the inner wall of the nozzle housing with the groove cut, and welding is performed around the perimeter to complete the processing of the engine tail pressure measuring structure. During the processing, protective measures are taken for the sealing surface of the nozzle housing to avoid scratches.

[0019] Finally, during the installation of the pressure testing structure, apply a layer of grease to both sides of the copper sealing gasket and place it at the countersunk hole of the pressure testing port (see...). Figure 2 When installing a pressure sensor or plug, it is recommended to control the tightening torque to (15~20) Nm.

[0020] The pressure testing port may not be compatible with the pressure sensor interface, but an adapter can be machined for pressure testing; the size, hardness, and installation torque of the copper sealing gasket can also be flexibly adjusted according to the actual situation; the shape of the variable cross-section pressure testing port channel is not limited to the patent schematic diagram example, and structures with similar functions can also be used.

[0021] The pressure measuring hole structure described in this invention has been applied in the pre-research project and has completed ground test verification, with a tail pressure measuring time of 120s.

[0022] Obviously, those skilled in the art can make various modifications and variations to the embodiments of the present invention without departing from the spirit and scope of the embodiments of the present invention. Thus, if these modifications and variations to the embodiments of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention also intends to include these modifications and variations.

[0023] This technology is applicable to pressure measurement at the tail of small solid rocket motors that operate for extended periods. It enables pressure measurement layout of small motors in compact spaces, improves the thermal insulation reliability of the pressure measurement area, and prevents the pressure measurement holes from being blocked. This is beneficial for obtaining pressure data during engine testing and has certain significance for improving the reliability and stability of pressure measurement in small motors.

Claims

1. A pressure measurement structure for the tail section of a small solid rocket motor suitable for long-term operation, characterized in that: It includes a non-metallic variable cross-section pressure measuring channel (1), a pressure measuring hole seat (2), a copper sealing gasket (3), a pressure measuring hole (4), and a plug (5). The pressure measuring hole seat (2) is welded to the metal shell of the nozzle. The pressure measuring hole (4) corresponds to the non-metallic cross-section pressure measuring channel (1). The copper sealing gasket (3) is placed in the groove of the pressure measuring hole seat. The plug (5) does not have a trapezoidal step. When a tightening torque is applied, the copper sealing gasket is compressed and deformed as a whole to achieve sealing.

2. The tail pressure measurement structure for a small solid rocket motor suitable for long-term operation as described in claim 1, characterized in that: The non-metallic variable cross-section pressure measuring channel has an inlet cone-shaped structure, which reduces the risk of engine ejection material blocking the channel.

3. The tail pressure measurement structure for a small solid rocket motor suitable for long-term operation as described in claim 1, characterized in that: The outer diameter of the copper sealing gasket is determined based on the minor diameter of the thread in the pressure test hole. A gap of 0.3mm to 0.5mm between the outer diameter and the minor diameter of the thread is sufficient to meet the requirements for gasket replacement after airtightness testing.

4. The tail pressure measurement structure for a small solid rocket motor suitable for long-term operation as described in claim 3, characterized in that: The inner diameter of the sealing gasket should be slightly larger than the inner diameter of the pressure testing hole channel.

5. The tail pressure measurement structure for a small solid rocket motor with long-term operation as described in claim 1, characterized in that: The depth of the threaded relief groove of the pressure testing hole seat is slightly greater than the thickness of the copper sealing gasket.

6. The tail pressure measurement structure for a small solid rocket motor suitable for long-term operation according to any one of claims 3 and 4, characterized in that: The thickness of the sealing gasket is 1.8mm~2.0mm; the hardness of the copper sealing gasket is (30~35)HB, and the surface finish of the copper gasket is not lower than Ra6.

3.

7. The tail pressure measurement structure for a small solid rocket motor suitable for long-term operation as described in claim 1, characterized in that: The pressure measuring hole seat (2) is installed in the groove at the 0.5mm countersunk hole of the nozzle metal shell, and the groove is welded around.

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