A fuel pump unloading tank design device to reduce cavitation

Abstract

This invention provides a novel fuel pump unloading groove design device to reduce cavitation, comprising gears, an inlet, an integrated snap-fit ​​block, a guide plate, and a mounting plate. Two gears are provided, each with an unloading groove at its upper and lower front ends. The inlet is located at the lower connection of the two gears, with symmetrical snap-fit ​​grooves on its left and right sides inside. Two integrated snap-fit ​​blocks are provided, each with a rubber mounting groove at its inner end. Elastic rubber protrusions are installed in each of the two rubber mounting grooves. The guide plate is fixed between the two integrated snap-fit ​​blocks. Compared to gear pumps without unloading grooves and traditional rectangular unloading groove gear pumps, this novel unloading groove gear pump effectively reduces the overall gas volume fraction in the pump's internal flow field without affecting the mass flow rate, thus mitigating the hazards of cavitation. Furthermore, it effectively reduces the gear pump's pulsation coefficient and improves the quality of the output flow.

Description

Technical Field

[0001] This invention relates to a novel fuel pump unloading groove design device for reducing cavitation, belonging to the field of fuel pump technology. Background Technology

[0002] Aviation fuel pumps are a key component of aircraft engines and are common hydraulic positive displacement devices. Their main function is to transport aviation fuel, and their performance has a significant impact on the operation of aircraft engines. Aviation fuel pumps mainly include gear pumps, centrifugal pumps, and piston pumps, among other structural forms. Gear pumps are characterized by their small size, high efficiency, and simple structure. Cavitation refers to the process of formation, development, and collapse of gas bubbles within a liquid or at the liquid-solid interface when the local pressure within the liquid decreases to a certain level. The pressure shock generated during bubble collapse is the main cause of cavitation. An unloading groove is a structure that can eliminate oil trapping in gear pumps, ensuring their stable operation.

[0003] In existing aviation fuel pumps, especially gear pumps operating at high speeds (greater than 5000 r·min⁻¹), the maximum and minimum pressures in the flow field are not located at the pump's outlet or inlet, but rather at the gear meshing point, with the maximum pressure significantly exceeding the design pressure at the gear outlet. Due to the pressure difference, the maximum flow velocity also occurs at the gear meshing point. Therefore, when designing high-speed gear pumps, the pressure and velocity distribution of the internal flow field should be considered to ensure product lifespan and reliability. As the gear speed increases from 5000 r·min⁻¹ to 7000 r·min⁻¹, the maximum and minimum values ​​of the gas volume fraction within the gear pump, as well as the gas distribution range shown in the cloud diagram, gradually increase, indicating that the cavitation degree within the gear pump's internal flow field also gradually increases. Therefore, when increasing the speed to improve fuel delivery efficiency, the impact of cavitation on product stability and lifespan should also be considered. Compared to ordinary gear pumps, aviation fuel pumps are characterized by high speed, large flow rate, and susceptibility to cavitation. Therefore, a novel unloading groove was designed to reduce the impact of cavitation, and the flow characteristics of the internal flow field were studied. The research results provide targeted theoretical support for future design research on aviation fuel pumps and have significant engineering implications. There is an urgent need for a new fuel pump unloading groove design device to reduce cavitation and solve the aforementioned problems. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to provide a novel fuel pump unloading groove design device to reduce cavitation, thereby solving the problems mentioned in the background art. Compared with gear pumps without unloading grooves and traditional rectangular unloading groove gear pumps, the novel unloading groove gear pump designed in this invention can effectively reduce the overall gas volume fraction in the flow field inside the gear pump without affecting the mass flow rate, thus mitigating the harm caused by cavitation; moreover, it can effectively reduce the pulsation coefficient of the gear pump and improve the quality of the output flow.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solution: a novel fuel pump unloading groove design device for reducing cavitation, comprising gears, an inlet, an integrated snap-fit ​​block, a guide plate, and a mounting plate. Two gears are provided, with unloading grooves at the upper and lower ends of their front sides. The inlet is located at the lower end connection of the two gears, with snap-fit ​​grooves symmetrically formed on the left and right ends inside the inlet. Two integrated snap-fit ​​blocks are provided, each with a rubber mounting groove at its inner end. Elastic rubber protrusions are installed in each of the two rubber mounting grooves. The guide plate is fixed between the two integrated snap-fit ​​blocks, with multiple tapered holes perforated at equal angles at its lower end. The mounting plate is horizontally installed at the lower end of the two integrated snap-fit ​​blocks using multiple miniature hexagonal socket head cap screws. Multiple through holes perforated at equal angles are formed on the lower end face of the mounting plate, with miniature filter screens installed at the upper ends of each of the through holes.

[0006] Furthermore, an outlet is provided through the connection point at the upper ends of the two gears.

[0007] Furthermore, a slanted opening is provided between the two gears.

[0008] Furthermore, arc-shaped grooves are provided on the inner sides of the two snap-fit ​​slots, and the two integrated snap-fit ​​blocks are respectively snapped into the two snap-fit ​​slots.

[0009] Furthermore, the two elastic rubber protrusions are respectively engaged in the two arc-shaped grooves.

[0010] Furthermore, all of the aforementioned tapered holes have a structure that is narrower at the top and wider at the bottom.

[0011] Furthermore, multiple micro-filters are horizontally mounted at the lower end of multiple conical holes.

[0012] The beneficial effects of this invention are as follows: This invention provides a novel fuel pump unloading groove design device for reducing cavitation. Because this invention incorporates gears, unloading grooves, integrated snap-fit ​​blocks, elastic rubber protrusions, guide plates, tapered holes, mounting plates, miniature hexagonal bolts, and miniature filter screens, our design improvements and practical use have shown that, compared to gear pumps without unloading grooves and traditional rectangular unloading groove gear pumps, this novel unloading groove gear pump effectively reduces the overall gas volume fraction in the gear pump's internal flow field without affecting the mass flow rate, thus mitigating the hazards caused by cavitation. Furthermore, it effectively reduces the gear pump's pulsation coefficient, improves the quality of the output flow, and can also filter and slow down the airflow at the inlet, assisting the unloading groove in reducing the internal flow field of the gear pump. Attached Figure Description

[0013] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0014] Figure 1 This is a three-dimensional schematic diagram of the overall structure of a novel fuel pump unloading groove design device for reducing cavitation according to the present invention.

[0015] Figure 2 This is a front view of the unloading groove of a novel fuel pump unloading groove design device for reducing cavitation according to the present invention;

[0016] Figure 3 This is a top view of the unloading groove of a novel fuel pump unloading groove design device for reducing cavitation according to the present invention;

[0017] Figure 4 This is a table showing the characteristic mass flow rate and pulsation coefficient of a novel fuel pump unloading groove design device for reducing cavitation according to the present invention.

[0018] Figure 5 This invention provides a parameter table for the unloading groove of a novel fuel pump unloading groove design device for reducing cavitation.

[0019] Figure 6 This is a schematic diagram of the inlet cross-section of a novel fuel pump unloading groove design device for reducing cavitation according to the present invention;

[0020] Figure 7 This is an enlarged view of the micro-filter screen position of a novel fuel pump unloading groove design device for reducing cavitation according to the present invention;

[0021] In the diagram: 1-Gear, 2-Outlet, 3-Inlet, 4-Unloading groove, 5-Angled opening, 6-Snap-fit ​​groove, 7-Integrated snap-fit ​​block, 8-Rubber mounting groove, 9-Elastic rubber protrusion, 10-Guide plate, 11-Conical hole, 12-Mounting piece, 13-Miniature hexagonal socket head cap screw, 14-Through hole, 15-Miniature filter screen. Detailed Implementation

[0022] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below in conjunction with specific embodiments.

[0023] Please see Figures 1-7 This invention provides a technical solution: a novel fuel pump unloading groove design device for reducing cavitation, comprising a gear 1, an inlet 3, an integrated snap-fit ​​block 7, a guide plate 10, and a mounting plate 12. Two gears 1 are provided, with unloading grooves 4 at the upper and lower ends of their front sides. The inlet 3 is located at the lower end connection of the two gears 1, with snap-fit ​​grooves 6 symmetrically formed on the left and right sides inside the inlet 3. Two integrated snap-fit ​​blocks 7 are provided, each with a rubber mounting groove 8 at its inner end. Elastic rubber protrusions 9 are installed in each of the two rubber mounting grooves 8. The guide plate 10 is fixed between the two integrated snap-fit ​​blocks 7, with multiple conical holes 11 extending through the lower end of the guide plate 10 at equal angles. The mounting plate 12 is horizontally installed on the lower end of the two integrated snap-fit ​​blocks 7 using multiple miniature hexagonal socket head cap screws 13. Multiple through holes 14 extend through the lower end face of the mounting plate 12 at equal angles, with miniature filter screens 15 installed on the upper ends of each through hole 14.

[0024] As the first embodiment of the present invention: an outlet 2 is provided through the connection of the upper ends of the two gears 1, and an oblique opening 5 is provided through the two gears 1. Through the oblique opening 5, the airflow at the inlet 3 can be moved to the unloading groove 4.

[0025] Both snap-fit ​​grooves 6 have arc-shaped grooves on their inner sides. Two integrated snap-fit ​​blocks 7 are respectively snapped into the two snap-fit ​​grooves 6. The addition of the two integrated snap-fit ​​blocks 7 makes it easy for the guide plate 10 to be installed horizontally inside the inlet 3. Two elastic rubber protrusions 9 are respectively snapped into the two arc-shaped grooves. The addition of the two elastic rubber protrusions 9 makes it less likely for the two integrated snap-fit ​​blocks 7 to loosen when they are snapped into the two snap-fit ​​grooves 6.

[0026] The multiple conical holes 11 are all narrow at the top and wide at the bottom. By adding multiple conical holes 11, the airflow speed at the inlet 3 can be adjusted. Multiple micro-filters 15 are horizontally installed at the lower end of the multiple conical holes 11. By adding multiple micro-filters 15, impurities carried by the airflow at the inlet 3 can be filtered.

[0027] As a second embodiment of the present invention: In actual use, the airflow enters the unloading groove 4 through the inlet 3 and the inclined opening 5. During this process, multiple micro-filters 15 can filter the impurities carried by the airflow entering the inlet 3, and multiple conical holes 11 can adjust the airflow speed entering the inlet 3.

[0028] In actual testing (Note: The model simplifies the existing unloading grooved gear pump model, focusing on aviation fuel gear pumps; considering the relatively small impact of chamfers and other structures on the flow field, the model is simplified based on the actual flow field), fluid simulation analysis is performed on the transmission unloading grooved gear pump to obtain optimization directions. The working state of the traditional gear pump is obtained through fluid simulation. The internal cavitation distribution, internal flow velocity distribution, and overall gas volume fraction of the gear pump are calculated numerically under a constant speed of 6000 r·min⁻¹ for gear pumps without unloading grooves, rectangular unloading grooved gear pumps, and a novel unloading grooved gear pump, yielding the distribution of relevant physical quantities. During gear meshing, severe oil trapping can affect the outlet flow rate and flow field quality. Simulation data from 0.02-0.04 s of the gear pump are used for post-processing analysis. Mass flow rate and pulsation coefficient are used to compare the flow quality of each gear pump (refer to...). Figure 4 );

[0029] Based on simulation data and related result cloud maps, the gear pump unloading groove is designed. Compared with the traditional rectangular unloading groove, this design proposes an asymmetric design and a ring gear groove design, which can effectively reduce cavitation in the gear pump. To obtain the best optimization results, fluid simulation tests are conducted with initial data offsets of 20% for the upper offset distance, lower offset distance, and tooth tip unloading groove angle. The initial upper offset distance is 20mm, the initial lower offset distance is 20mm, and the initial tooth tip unloading groove angle is 130°. After multiple simulation analyses and optimization using response surface methodology, the following optimal unloading groove parameters are obtained (reference). Figure 5 The newly designed unloading grooved gear pump, compared to gear pumps without unloading grooves and traditional rectangular unloading grooved gear pumps, effectively reduces the overall gas volume fraction in the internal flow field of the gear pump without affecting the mass flow rate, thus mitigating the hazards caused by cavitation. Furthermore, it effectively reduces the pulsation coefficient of the gear pump and improves the quality of the output flow. In gear pumps with high speeds (greater than 5000 r·min⁻¹), the maximum and minimum pressures of the flow field are not located at the outlet or inlet of the gear pump, but rather at the gear meshing point, and the maximum pressure is much greater than the design pressure at the gear outlet. Due to the influence of pressure difference, the maximum flow field velocity also occurs at the gear meshing point. Therefore, when designing high-speed gear pumps, the pressure and velocity distribution of the internal flow field should be considered to ensure the product's lifespan and reliability. As the gear speed increases from 5000 r·min⁻¹ to 7000 r·min⁻¹, the maximum and minimum values ​​of the gas volume fraction inside the gear pump, as well as the gas distribution range shown in the cloud diagram, all gradually increase, indicating that the degree of cavitation in the internal flow field of the gear pump also gradually increases. Therefore, when increasing the rotational speed to improve oil delivery efficiency, the impact of cavitation on product stability and lifespan should also be considered.

[0030] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the scope of the invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0031] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A fuel pump unloading groove design device for reducing cavitation, comprising a gear (1), an inlet (3), an integrated snap-fit ​​block (7), a guide plate (10), and a mounting plate (12), characterized in that: Two gears (1) are provided, and unloading grooves (4) are opened at the upper and lower ends of the front side of the two gears (1). The inlet (3) is located at the lower end connection of the two gears (1). The entrance (3) has symmetrical snap-fit ​​grooves (6) on the left and right sides inside. There are two integrated snap-fit ​​blocks (7). The two integrated snap-fit ​​blocks (7) have rubber mounting grooves (8) on their inner ends. Elastic rubber protrusions (9) are installed in the two rubber mounting grooves (8). The guide plate (10) is fixed between two integrated snap-fit ​​blocks (7). The lower end of the guide plate (10) has multiple conical holes (11) through it at equal angles. The mounting plate (12) is horizontally installed at the lower end of the two integrated snap-fit ​​blocks (7) by multiple miniature hexagonal bolts (13). The lower end face of the mounting plate (12) has multiple through holes (14) through it at equal angles. Miniature filter screens (15) are installed at the upper end of each of the multiple through holes (14).

2. The fuel pump unloading groove design device for reducing cavitation according to claim 1, characterized in that: An outlet (2) is provided through the connection at the upper end of the two gears (1).

3. The fuel pump unloading groove design device for reducing cavitation according to claim 1, characterized in that: A slanted opening (5) is provided between the two gears (1).

4. The fuel pump unloading groove design device for reducing cavitation according to claim 1, characterized in that: The two snap-fit ​​slots (6) are provided with arc-shaped grooves on their inner sides, and the two integrated snap-fit ​​blocks (7) are respectively snapped into the two snap-fit ​​slots (6).

5. The fuel pump unloading groove design device for reducing cavitation according to claim 4, characterized in that: The two elastic rubber protrusions (9) are respectively engaged in the two arc-shaped grooves.

6. The fuel pump unloading groove design device for reducing cavitation according to claim 1, characterized in that: All of the tapered holes (11) have a structure that is narrow at the top and wide at the bottom.

7. The fuel pump unloading groove design device for reducing cavitation according to claim 1, characterized in that: Multiple micro-filters (15) are horizontally mounted inside the lower end of multiple conical holes (11).

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