Underwater cross-medium solid engine test bench

Abstract

The invention discloses an underwater cross-medium solid engine test bed which comprises a portal frame, a movable and fixed frame assembly, a force measurement assembly, a thrust calibration device, a winch, a limiting and locking device and a spring piece assembly. The movable and fixed frame assembly adopts a combined machining process, and after being positioned through a process spring piece, the process spring piece is replaced with a working spring piece, so that high-precision assembly is realized; the force measuring assembly and the thrust calibration device are coaxially arranged and are far away from an engine nozzle, the thrust calibration device eliminates lateral force through a ball bowl type traction structure, and the winch drives the movable and fixed frame assembly to ascend and descend along the oil-free linear sliding rail. Through optimization of the structure, the position, the connection and the matching relation, the technical problems that an existing underwater test bed is low in installation precision, measurement is interfered by temperature excursion, calibration lateral force is interfered, and rigidity and freedom degree are unbalanced are solved, high-precision measurement within the preset thrust range is achieved, and the thrust test bed is suitable for thrust tests of various underwater and water engines and has good application prospects. The measurement precision is not lower than 0.5% FS, and the lifting action is stable and reliable.

Description

Technical Field

[0001] This invention relates to the field of engine testing equipment technology, specifically to an underwater transmedium solid rocket motor test bench, suitable for measuring the horizontal thrust of an engine in both above-water and underwater environments. Background Technology

[0002] As the core power component of underwater vehicles, the thrust performance of underwater engines directly affects the maneuverability and endurance of the vehicles. Therefore, a dedicated test stand is required for precise measurement of their thrust. Existing underwater test stands have the following technical deficiencies in structural design and performance implementation: Insufficient installation accuracy: Traditional moving and stationary frames are assembled after separate processing, which can easily lead to uneven stress on the spring plates due to processing errors and assembly deformation, affecting the release of horizontal degrees of freedom and thus increasing measurement errors; Severe temperature drift interference: The force sensor is located close to the engine nozzle, and the heat radiation from the engine exhaust directly affects the sensor, resulting in excessive temperature drift and reduced measurement accuracy. Poor calibration accuracy: The line of action of the calibration force does not coincide with the center line of engine thrust, and the tensioning structure is prone to generating lateral force, resulting in poor calibration linearity and inability to truly simulate engine thrust; Imbalance between stiffness and degree of freedom: It is difficult to achieve both high degree of freedom in the horizontal direction (to ensure accurate thrust transmission) and high lateral stiffness (to withstand non-axial loads) at the same time, resulting in insufficient stability of the test bench; Low maintenance convenience: The disassembly and assembly process of core components (such as spring plates) is complicated, and they are prone to fatigue damage under long-term stress, which affects the service life of the equipment.

[0003] To address the aforementioned issues, this invention provides a high-precision, highly stable, and easily maintained underwater transmedium solid rocket motor test bench by optimizing structural design, spatial layout, connection methods, and mating relationships. Summary of the Invention

[0004] The purpose of this invention is to provide an underwater transmedium solid rocket motor test bench that achieves high-precision thrust measurement through optimization of structure, position, connection and fit, thereby solving problems such as low installation accuracy, temperature drift interference, calibration deviation and stiffness imbalance in the prior art.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A test bench for an underwater transmedium solid rocket motor, with key components numbered as follows: 1-Gantry, 2-Moving and stationary frame assembly (21-Stationary frame, 22-Moving frame, 23-Engine mounting bracket), 3-Force measuring assembly (31-Pull-compression sensor, 32-Adjusting rod, 33-Joint bearing tie rod), 4-Thrust calibration device (41-Drive force mechanism / lifting machine, 42-Calibration sensor, 43-Spherical cup type traction structure), 5-Wind, 6-Limit locking device, 7-Spring plate assembly, 8-Lifting mechanism / hand chain hoist, 9-Oil-free linear guide rail.

[0006] The structure, connection, and mating relationships of each component are as follows: Gantry (1): Structure: It adopts an inverted U-shaped structure, spanning the test water tank, to provide basic support for the entire test stand; Connection: After leveling with the on-site cement foundation, it is fixed with expansion bolts to ensure installation stability; Fitting relationship: It is made of high-strength steel plate and steel pipe welded together, and stress relief treatment is performed after welding to avoid deformation during processing and installation; hanging rails are arranged on both sides, and a lifting mechanism (8) is installed on the hanging rails for the lifting and disassembly of the engine; Core function: To bear the overall load of the test bench and the thrust of the engine, and to provide an installation foundation for the lifting and lowering of the dynamic and stationary frame assembly (2).

[0007] Dynamic and static frame assembly (2): Structure: The core force transmission and installation structure includes a fixed frame (21), a moving frame (22) and an engine mounting frame (23); both the fixed frame (21) and the moving frame (22) are welded structures, and the weld grade meets the preset strength requirements; Processing technology (key innovation in fit and fit): A combined processing technology is adopted. After rough machining, the "process spring sheet" is used for positioning and combined for fine machining to ensure the positional accuracy of the front and rear end mounting surfaces and mounting holes. After fine machining, the process spring sheets are removed one by one and replaced with working spring sheets (7) to avoid installation stress caused by assembly deformation. Connection relationship: The upper sides of the fixed frame (21) are connected to the front and rear ends of the gantry frame (1) by oil-free linear slide rails (9) respectively, and can move smoothly in the vertical direction; the moving frame (22) is elastically connected to the fixed frame (21) by multiple sets of spring plate assemblies (7) to form a one-way flexible degree of freedom system. The upper end of each set of spring plate assemblies is fixed to one end of the fixed frame near the corner by screws, and the lower end is fixed to the corresponding end of the moving frame near the corner by screws. The four corners of the fixed frame and the moving frame are connected by spring plate assemblies; the engine mounting bracket (23) can be detachably installed on the adjustable structure below the moving frame (22); Core function: to fix the engine and auxiliary equipment, transmit the engine thrust to the force measuring component (3), and realize the engine's entry and exit from the water by cooperating with the winch (5).

[0008] Force measuring component (3): Structure: Includes a tension / compression sensor (31), an adjusting rod (32), a spherical bearing tie rod (33), and a mounting base; Positional relationship: Arranged at the end of the moving and fixed frame assembly (2) away from the engine nozzle to avoid sensor temperature drift caused by engine tail spray heat radiation; Connection relationship: The tension-compression sensor (31) is horizontally installed between the fixed frame (21) and the moving frame (22). The two ends of the tension-compression sensor (31) are connected to the fixed frame (21) and the moving frame (22) respectively through a joint bearing rod (33). The force transmission path is set along the axial direction, which is the shortest and most optimal. The two joint bearing rods are installed with a 90-degree rotational misalignment to avoid the rotational torque affecting the accuracy of the tension-compression sensor (31). One of the two mounting seats is installed at the lower end of the fixed frame and the other is installed at the upper end of the moving frame. One end of the adjusting rod is connected to the mounting seat at the upper end of the moving frame, and the other end of the adjusting rod is connected to a joint bearing rod through a flange. The mounting seat at the lower end of the fixed frame is connected to another joint bearing rod through a flange. Matching relationship: The joint bearing structure can adapt to small angular deviations and eliminate the interference of lateral force on axial thrust measurement; the tension-compression sensor (31) has an accuracy of not less than 0.5%FS and is connected to the host computer data acquisition system through the communication interface to realize real-time acquisition of thrust data.

[0009] Thrust calibration device (4): Structure: Includes a driving force mechanism (41), a calibration sensor (42), a ball-and-socket traction structure (43), and a connecting seat; Position and fit: It is arranged coaxially with the force measuring component (3), and the center line of the calibration sensor (42) coincides with the center line of the engine thrust, so as to ensure that the calibration force is consistent with the direction of the engine thrust; Connection relationship: The driving force mechanism (41) is a manual worm gear lift, which is fixed to the fixed frame (21) by the mounting rod; it is connected to the center point of the rear end face of the engine mounting bracket (23) installed at the lower end of the moving frame (22) by the ball cup traction structure (43). During the calibration process, the gap between the traction rod and the ball cup is eliminated to avoid generating additional lateral force; Core function: to provide standard tension, realistically simulate engine thrust, and accurately calibrate the force measuring component (3), with a calibration accuracy of not less than 0.5%FS.

[0010] Winch (5): Structure: It adopts a dual-drum structure driven by a servo motor, equipped with a servo driver, which supports speed adjustment and precise start and stop; Connection relationship: It is connected to the lifting point on the fixed frame (21) and the moving fixed frame assembly (2) is pulled up and down along the oil-free linear slide rail (9) by steel wire rope; Coordination: The dual-drum structure ensures a smooth lifting process, and the servo motor drive enables automatic lifting, meeting the simulation requirements of engine water entry and exit.

[0011] Limit locking device (6): Structure: Four sets in total, including locking nuts, safety seats, and anti-loosening components; Positional relationship: respectively installed on the front and rear end faces of the moving and fixed frame assembly (2), corresponding to the arrangement position of the spring plate assembly (7); Coordination: Under the force measurement state, the locking nut and the moving frame (22) maintain a preset gap, which does not affect the horizontal movement of the moving frame (22); when the equipment is maintained or shut down for a long time, the moving frame (22) is locked so that the spring plate assembly (7) and the force measuring assembly (3) are not subjected to force, which plays a protective role; the anti-loosening structure with double nuts and fuses is adopted to avoid loosening caused by vibration and impact.

[0012] Spring sheet assembly (7): Structure: Multiple symmetrical arrangements (preferably four groups), made of spring steel, with multi-layer nickel plating on the surface, but bolt holes are not nickel plated; Processing and fit relationship: The surface roughness of the mounting surface is not less than Ra1.6, the key mating surface is not less than Ra0.8, and the parallelism of the left and right planes and the parallelism of the two end faces are better than the preset threshold; the axial elastic resistance is small, ensuring the high degree of freedom of the moving frame (22) in the horizontal direction; the lateral and vertical stiffness is high, which can withstand non-axial loads and achieve a balance between stiffness and degree of freedom; Connection relationship: It is connected to the mounting plates of the fixed frame (21) and the moving frame (22) by bolts, which facilitates disassembly and maintenance.

[0013] Other auxiliary components: Lifting mechanism (8): is a hand-operated hoist, installed on the lifting rail of the gantry (1), used for lifting the engine; Oil-free linear guide rail (9): installed between the fixed frame (21) and the gantry (1), it bears axial force and lateral force while ensuring smooth lifting of the moving and fixed frame assembly (2).

[0014] Thrust calibration method: Based on the thrust calibration method described above for the test stand, the specific steps are as follows: Installation preparation: Fix the engine to the moving frame (22) via the engine mounting bracket (23), and use a flexible hose to connect the engine pipeline to reduce pipeline stress interference; lock the limiting locking device (6) to avoid stress on the spring plate assembly (7) during installation; System preheating: Start the force measuring component (3), thrust calibration device (4) and data acquisition system, and preheat for a preset time (10 minutes in the example) to ensure stable operation of the equipment; Preload cycle: The thrust calibration device (4) performs a "load-release" cycle at least a preset number of times (5 times in the example) to load to a preset thrust value (700 kg in the example) and then slowly releases to the initial state to eliminate system gaps and component elastic hysteresis; Formal calibration: Record the detection data of the tension and compression sensor (31) and the calibration sensor (42) at preset intervals (50kg in the example). Record the process calibration (loading process) and return calibration (release process) separately, repeating at least a preset number of sets (3 sets in the example) to ensure data reliability; Formula fitting: The least squares method is used to fit the thrust formula F=kx+b, and the fitted k and b values ​​are input into the self-developed measurement and control software; Verification and correction: The force value is monitored synchronously by three independent software programs (self-developed measurement and control software, software built into the tension and compression sensor, and software built into the calibration sensor). If the error does not exceed the preset threshold (2% in the example), the calibration is valid; otherwise, recalibrate or correct the fitting parameters. Preload correction: Set the preload value according to the zero-crossing situation during the calibration process, repeat the calibration a preset number of times (3 times in the example), and complete the measurement calibration correction after preload to carry out engine thrust test.

[0015] Compared with the prior art, the present invention has the following advantages: Significantly improved installation accuracy: The moving and stationary frames adopt an innovative process of combined processing and spring plate positioning, which effectively avoids processing errors and assembly deformation. The spring plate installation stress is uniform, the horizontal degree of freedom is fully released, and the measurement error is greatly reduced. Effective suppression of temperature drift interference: The force measurement component and thrust calibration device are arranged far away from the engine nozzle, reducing the impact of tail spray heat radiation on the sensor, reducing sensor temperature drift, and maintaining measurement accuracy above 0.5%FS; High calibration accuracy: The calibration sensor is coaxial with the engine centerline, the ball-and-socket traction structure eliminates lateral force interference, the calibration force is consistent with the direction of engine thrust, the linearity is excellent, and the calibration accuracy is not less than 0.5%FS; Stiffness and freedom balance: The spring plate assembly adopts a two-way stiffness design with low axial elastic resistance and high lateral stiffness, which ensures high freedom in the horizontal direction of the moving frame and can withstand non-axial loads. The overall deformation and stress of the platform meet the safety requirements, and the safety factor is not less than 3. Improved ease of maintenance: The spring sheets are bolted together and can be disassembled and replaced one by one; the limit locking device locks the moving frame during maintenance, avoiding long-term stress fatigue of core components and extending the service life of the equipment; High versatility: It does not limit the specific thrust range or test bench size. By adjusting the component parameters, it can be adapted to test different models and thrust levels of engines, making it widely applicable. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the overall structure of the present invention.

[0017] Figure 2 This is a schematic diagram of the structure of the moving and stationary frame assembly of the present invention.

[0018] Figure 3 This is a three-dimensional rendering of the force measuring component of the present invention.

[0019] Figure 4 This is a partially enlarged schematic diagram of the thrust calibration device structure of the present invention.

[0020] Figure 5 This is a partial schematic diagram of the gantry frame of the present invention. Detailed Implementation

[0021] The present invention will be further described in detail below with reference to specific embodiments: Example

[0022] This embodiment provides a lifting underwater test stand suitable for engines with a thrust of 700 kgf. The specific parameters of the key components (this is only an embodiment and does not constitute a limitation of the claims) are as follows: Gantry frame (1): It is made of Q355 steel plate, with external dimensions of 3210×2360×4265mm. After welding, stress relief treatment is performed, with total deformation ≤0.9mm and equivalent stress ≤65.8MPa. Moving and stationary frame assembly (2): Both the stationary frame (21) and the moving frame (22) are made of Q355 square tube and steel plate welded together. The weld is made in accordance with the first-class weld of QJ176B-2016 and the installation surface level is 0.05mm / 1000mm. Spring sheet assembly (7): Made of 65Mn spring steel, with a nickel plating thickness of 0.03~0.05mm and a parallelism better than 0.05mm; Force measuring component (3): The tension and compression sensor (31) is a DYMH-107 diaphragm sensor with a range of 1000kg and an accuracy of ±0.5%FS; Thrust calibration device (4): The driving force mechanism (41) is a SWL series manual worm gear lift with a rated load capacity of 1000kg and a reduction ratio of 6:1~32:1. Winch (5): Selected Hechuan SV-X6MG290A-B4LD servo motor, rated power 2.9kW, lifting stroke 2.5m, lifting speed 0.05m / s; Limit locking device (6): M24 bolts are used, double nuts are added with φ1.2mm fuse to prevent loosening, and the gap between the device and the moving frame (22) is 5mm under the force measurement state. Example

[0023] The engine thrust was tested using the test bench described in Example 1, and the calibration process is as follows: After installing the engine, tighten the limit locking device (6), connect the hose line, and ensure that there is no obvious stress on the line. Start the system and warm it up for 10 minutes; Perform 5 "load-release" cycles, load to 700kg, stabilize for 3 seconds, and then release. Three formal calibrations were performed, with 15 sets of data recorded for both the forward and return journeys. The thrust formula F = 0.998x + 0.32 was obtained through fitting. During the verification phase, the readings from the three software programs under a 350kg load were 349.2kg, 349.5kg, and 349.3kg, respectively, with an error of 0.23%, which meets the requirements. The preload was set to 5kg, and the calibration was repeated 3 times. Finally, the formula F=0.999x+0.21 was determined, and the calibration was completed.

[0024] Test results show that the test stand has a maximum error of ≤0.5%FS in measuring engine thrust in an underwater environment, the lifting action is smooth, the limit locking device is reliable, and it meets the design requirements.

[0025] This invention addresses the core technical deficiencies of existing underwater test stands by optimizing their structure, position, connection, and fit. It can be widely applied to thrust performance testing of various small and medium-sized underwater and surface engines, providing precise data support for engine development and optimization.

Claims

1. A test bench for an underwater transmedium solid rocket motor, characterized in that, include: The gantry (1) is an inverted U-shaped structure that spans the test water tank and is fixed to the concrete foundation with expansion bolts to provide overall support. The moving and fixed frame assembly (2) includes a fixed frame (21), a moving frame (22), and an engine mounting bracket (23). The fixed frame (21) is slidably connected to the gantry (1) via an oil-free linear slide rail (9), and the moving frame (22) is elastically connected to the fixed frame (21) via multiple sets of spring plate assemblies (7). The engine mounting bracket (23) is detachably installed on the moving frame (22). The force measuring component (3) is installed at the end of the moving and fixed frame assembly (2) away from the engine nozzle and is used to detect engine thrust. The force measuring component (3) is connected to the engine nozzle via an expansion bolt. The spherical bearing structure eliminates lateral force interference; the thrust calibration device (4) is arranged coaxially with the force measuring component (3), and its force centerline coincides with the engine thrust centerline. It includes a driving force mechanism (41), a calibration sensor (42), and a ball-and-socket type traction structure (43). It simulates engine thrust through a pull loading method to achieve calibration of the force measuring component (3); the winch (5) is connected to the fixed frame (21) for driving the moving and fixed frame assembly (2) to rise and fall along the oil-free linear slide rail (9); the limit locking device (6) is installed on the front and rear end faces of the moving and fixed frame assembly (2) to limit the position of the moving frame (22) and protect the spring plate assembly (7) and the force measuring component (3).

2. The underwater transmedium solid rocket motor test bench according to claim 1, characterized in that, The moving and fixed frame assembly (2) adopts a combined processing technology: after the fixed frame (21) and the moving frame (22) are rough processed, they are positioned by process spring plates and combined for fine processing. After the fine processing is completed, the process spring plates are removed and replaced one by one with working spring plates, i.e., spring plate assembly (7); both the fixed frame (21) and the moving frame (22) adopt a welded structure. After welding, they are subjected to stress relief treatment, and the horizontality of the mounting surface meets the preset accuracy requirements.

3. The underwater transmedium solid rocket motor test bench according to claim 1, characterized in that, The spring plate assembly (7) consists of four groups, symmetrically arranged on the front and rear end faces of the fixed frame (21) and the moving frame (22), and is made of spring steel. The spring plate assembly (7) has a preset elastic resistance in the axial direction to release the horizontal degree of freedom, and a preset stiffness in the lateral and vertical directions to withstand non-axial loads.

4. The underwater transmedium solid rocket motor test bench according to claim 3, characterized in that, The surface roughness of the mounting surface of the spring plate assembly (7) is not less than Ra1.6, the surface roughness of the key mating surface is not less than Ra0.8, and the parallelism of the left and right planes and the parallelism of the two end faces are better than the preset parallelism threshold. The outer surface of the spring plate assembly (7) is treated with multi-layer nickel plating, and the bolt holes are not nickel plated.

5. The underwater transmedium solid rocket motor test bench according to claim 1, characterized in that, The force measuring component (3) includes a tension-compression sensor (31), an adjusting rod (32), and a joint bearing tie rod (33). The tension-compression sensor (31) is horizontally installed between the fixed frame (21) and the moving frame (22), and the force transmission path is set along the axial direction. The combined accuracy of the tension-compression sensor (31) and the calibration sensor (42) is not less than 0.5%FS, and both are connected to the host computer data acquisition system through a communication interface.

6. The underwater transmedium solid rocket motor test bench according to claim 1, characterized in that, The driving force mechanism (41) of the thrust calibration device (4) is a manual worm gear lift, which adopts a T-shaped screw structure and is connected to the center point of the rear end face of the moving frame (22) through a ball cup traction structure (43). During the calibration process, the gap between the pull rod and the ball cup is eliminated to achieve no lateral force loading.

7. The underwater transmedium solid rocket motor test bench according to claim 1, characterized in that, The winch (5) adopts a double drum structure driven by a servo motor and is connected to the lifting point on the fixed frame (21) to realize the automatic lifting of the moving and fixed frame assembly (2); the gantry (1) is arranged with hanging rails on both sides, and a lifting mechanism (8) is installed on the hanging rails for the lifting of the engine.

8. The underwater transmedium solid rocket motor test bench according to claim 1, characterized in that, The limiting locking device (6) consists of four sets, which maintain a preset gap with the moving frame (22) under force measurement and lock the moving frame (22) under equipment maintenance or long-term shutdown. The limiting locking device (6) adopts an anti-loosening structure to withstand the vertical and lateral forces generated by the engine unexpectedly.

9. The underwater transmedium solid rocket motor test bench according to claim 1, characterized in that, The engine mounting bracket (23) includes a flange mounting bracket, a self-aligning device and a tail triangular tie rod, which are installed on the moving frame (22) through an adjustable connection structure. The engine pipeline is connected by a flexible hose to reduce pipeline stress interference.

10. A thrust calibration method based on the test bench according to any one of claims 1-9, characterized in that, Includes the following steps: 1) Fix the engine and auxiliary pipelines with the engine mounting bracket (23) and lock the limit locking device (6) to ensure that the pipeline connection meets the preset stress requirements; 2) Start the measurement and calibration system and preheat for a preset time; 3) Perform at least a preset number of "load-release" cycles through the thrust calibration device (4), load to the preset thrust value and then slowly release to the initial state; 4) During the formal calibration stage, record the detection data of the force measuring component (3) and the thrust calibration device (4) at preset intervals, record the process calibration and return calibration separately, and repeat at least a preset number of sets; 5) Fit the thrust formula using the least squares method and input the fitting parameters into the measurement and control software; 6) Monitor the force value synchronously through multiple independent software. If the error does not exceed the preset threshold, the calibration is effective. Otherwise, recalibrate or correct the parameters; 7) Set the preload value according to the zero-crossing point and repeat the calibration a preset number of times to complete the correction.

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