Composite-based fuel pump housing structure and its design method

Abstract

This invention discloses a composite fuel pump housing structure and its design method. The housing structure includes a housing body, an inlet section on the upper part of the housing, an outlet section on the side of the housing, a pump core mounting flange connecting the internal pump core structure of the fuel pump, a pump housing mounting flange realizing the fuel pump housing, and overlapping plates laid in the housing body. This invention effectively solves the practical application problem of composite materials in fuel pump housings of aerospace electromechanical systems, paving the way for the large-scale use of composite materials in aerospace electromechanical systems, reducing the weight of aerospace electromechanical products, and providing a new solution for the lightweighting of aerospace electromechanical systems.

Description

Technical Field

[0001] This application belongs to the field of aviation electromechanical systems and relates to a fuel pump housing structure based on composite materials and its design method. Background Technology

[0002] Resin-based composite materials have been widely used in the aerospace field due to their advantages such as high specific strength and specific modulus, low material density, excellent corrosion resistance, good dielectric properties, strong designability, and diverse molding processes. Advanced military and civilian aircraft structures extensively utilize resin-based composite materials; for example, the US F-22 fighter jet uses 24% resin-based composite materials, the F-35 fighter jet uses 35%, and the B787 aircraft uses as much as 50%. Similar to the development trend of aircraft structures, the amount and proportion of resin-based composite materials used in aircraft electromechanical systems are also gradually increasing. With the trend towards lightweight aircraft, the amount of composite materials used has even become a direct measure of the level of advancement in the aerospace field. In aerospace electromechanical systems, fuel pump housings, due to their functions such as spiral flow channels and supporting installation, are generally complex in shape and large in size, accounting for a significant portion of the weight of fuel pump products. Using resin-based composite materials to design fuel pump housings can not only reduce product weight but also lower manufacturing costs and improve mechanical and fatigue characteristics. However, there are still many problems in designing and manufacturing fuel pump housings using composite materials. For example, it is difficult to form complex composite structures, the threaded connection strength of composite components is insufficient, the forming dimensional accuracy of composite components is not sufficient during assembly, and the electrical bonding performance is poor due to the non-conductive properties of composite materials. These problems need to be addressed through targeted research under real-world conditions, and solutions need to be proposed to break through the composite material design and manufacturing technology of typical housing structures. Summary of the Invention

[0003] The purpose of this invention is to provide a fuel pump housing structure based on composite materials and its design method, which solves the problems of difficult molding of complex structures, insufficient strength of threaded connections, insufficient machining accuracy of mating dimensions, and poor electrical bonding performance in the application of composite materials, thus paving the way for the widespread application of composite materials in aerospace electromechanical systems.

[0004] To achieve the above objectives, the present invention employs the following technical solution:

[0005] A composite fuel pump housing structure includes a housing body 5, an inlet section 1 disposed on the upper part of the housing body 5, an outlet section 2 disposed on the side of the housing body 5, a pump core mounting flange 3 connecting the internal pump core structure of the fuel pump, a pump housing mounting flange 4 realizing the fuel pump housing, and an overlapping piece 6 laid in the housing body 5, wherein:

[0006] The main body 5 of the housing is a cylindrical component, including the upper volute flow channel housing, the middle pump core mounting housing, and the flange in the lower pump housing mounting flange 4; the middle part of the main body 5 is the pump core mounting housing, which is cylindrical. The inner cavity of the pump core mounting housing is adapted to the outer shape of the pump core part. The lower flange has an annular symmetrical structure. The outer circumference of the lower flange is provided with reinforcing ribs. The threaded insert 4-1 is installed inside the reinforcing ribs. The edges of the reinforcing ribs that intersect with the pump core mounting housing are provided with rounded corners.

[0007] The inlet section 1 is a cylindrical component that connects to the system pipeline at the fuel inlet of the fuel pump, drawing fuel from the system into the product housing. After the pump core is installed in the housing body 5, the impeller is located in the middle of the inlet section 1 and the volute housing. A sealing groove 1-1 is provided on the outer wall of the inlet section 1, and a rubber sealing ring is installed in the sealing groove 1-1. An inlet mounting flange 1-2 is provided on the outside of the inlet section 1. The lower part of the inlet section 1 is inserted into the upper end of the housing body 5, and an outward flange structure 1-3 is provided at the lower end of the inlet section 1 where it connects with the fuel pump housing body 5.

[0008] Outlet section 2 has a trumpet-shaped structure and is connected to the outer end of the volute flow channel housing. The diameter of outlet section 2 gradually decreases from the outer end to the inner end. The axis of the outer end face of outlet section 2 points to the central axis of the volute flow channel housing. Outlet section 2 is connected to the system pipeline at the fuel pump outlet. The fuel, after being pressurized by the fuel pump, flows out of the fuel pump through outlet section 2 and into the system pipeline. A pressure measuring port 2-1 is provided on outlet section 2. The pressure measuring port 2-1 has a columnar structure and is hollow inside, communicating with the inner cavity of outlet section 2. A pressure sensor is used to sense the fuel pressure in outlet section 2 through pressure measuring port 2-1.

[0009] The pump core mounting flange 3 is a cylindrical component located at the bottom end of the housing body 5. The inner cavity of the pump core mounting flange 3 is adapted to the shape of the pump core part installed inside the fuel pump housing, and a clearance fit is adopted.

[0010] The pump casing mounting flange 4 is located on the outside of the lower end of the casing body 5. The pump casing mounting flange 4 includes multiple threaded inserts 4-1 and a flange. The flange adopts an integrated design with the casing body 5. The threaded inserts 4-1 are evenly distributed in the assembly holes on the lower end face circumference of the pump casing mounting flange 4 and are embedded in the flange. The inner cavity of the threaded insert 4-1 is internally threaded, the outer ring is a sawtooth structure, and a stepped structure is provided in the axial direction of the outer ring.

[0011] The overlapping piece 6 is a long strip of metal. The overlapping piece 6 includes a connecting piece connecting the inlet section 1 and the outlet section 2, a connecting piece connecting the outlet section 2 and the pump core mounting flange 3, and a connecting piece connecting the pump core mounting flange 3 and the threaded insert 4-1. The connecting piece is lined into the composite material of the housing body 5.

[0012] Furthermore, after being pressurized by work in the impeller, the fuel flows into the volute casing, where it undergoes further energy conversion before flowing into outlet section 2. The cross-sectional area of ​​the volute casing gradually increases from the inside to the outside of the volute, adapting to the flow rate of the fuel. The cross-sectional area is circular, horseshoe-shaped, or rectangular, and the wall thickness of the volute casing is 3–5 mm.

[0013] Furthermore, an installation flange is provided at the connection between the outlet section 2 and the system pipeline. The installation flange is connected to the system pipeline and has a regular annular structure. The thickness of the installation flange is generally 5 to 10 mm. A sealing groove 1-1 is provided on the end face of the installation flange, and a sealing ring is installed inside. The end face sealing method is used to prevent fuel leakage at the connection. The compression of the sealing ring is generally between 10% and 20%.

[0014] Furthermore, the inner wall dimensional accuracy of the pump core mounting flange 3 is grade 7; the surface finish is at least Ra1.6; the outer wall of the pump core mounting flange 3 is rough or designed as serrated; the bottom end face of the pump core mounting flange 3 is provided with threaded holes, of which 1 to 2 holes are arranged in a non-uniform manner, and a weight reduction groove is designed between every two mounting holes.

[0015] Furthermore, the width of the lap joint is 3-8mm, the thickness is 0.4-1mm, and the length is cut according to actual needs; the material of the lap joint is pure copper or copper alloy.

[0016] A composite-based fuel pump housing design method, comprising:

[0017] Step 1: Design the mold according to the shape and interface size of the fuel pump housing. There are two types of molds: positioning mold and forming mold.

[0018] The positioning mold is an "L"-shaped mounting base 7. A base plate 7-1 is fixedly mounted on the "L"-shaped mounting base 7. The mounting base 7-1 has multiple rings of positioning holes from the outside to the inside, which are opened according to the shell interface size. These holes are used to position the threaded insert 4-1 on the pump shell mounting flange 4, the threaded hole on the internal pump core mounting flange 3, and the metal column 7-2. The other end of the metal column 7-2 is connected to the inlet mounting flange 1-2 on the inlet section 1 through a positioning connector 7-2a. A positioning cylinder 7-3 is provided on the side plate of the mounting base 7. The positioning cylinder 7-3 is cylindrical. One end is fixed to the side plate of the "L"-shaped mounting base 7 by screwing or welding, and the other end has threaded mounting holes. The number and position of the threaded mounting holes are consistent with the mounting holes of the outlet mounting flange 2-3 in the outlet section 2.

[0019] The molding mold includes two types: one is a core mold installed inside the shell structure, which adopts a water-soluble core mold 7a integral molding process; the other molding mold is an auxiliary silicone outer film 7b installed outside the shell structure.

[0020] Step 2: Design the shape and installation dimensions of inlet section 1 according to the shape and interface dimensions of the fuel pump housing, and process it by machining.

[0021] Step 3: Design the shape and installation dimensions of outlet section 2 according to the shape and interface dimensions of the fuel pump housing, and process it by machining.

[0022] Step 4: Design the shape and installation dimensions of the pump core mounting flange 3 according to the shape and interface dimensions of the fuel pump housing, and process it into shape using machining.

[0023] Step 5: Design the shape and installation dimensions of the threaded insert 4-1 in the pump housing mounting flange 4 according to the shape and interface dimensions of the fuel pump housing, and process it by machining.

[0024] Step 6: Cut overlapping pieces 6 from the profile according to the shape and size of the fuel pump housing. The overlapping pieces 6 include three specifications: a connecting piece for connecting the inlet section 1 and the outlet section 2, a connecting piece for connecting the outlet section 2 and the pump core mounting flange 3, and a connecting piece for connecting the pump core mounting flange 3 and the threaded insert 4-1.

[0025] Step 7: Assemble using the mold, specifically as follows:

[0026] Install and fix the threaded insert 4-1 onto the outer threaded hole of the mounting base plate 7-1;

[0027] Install and fix the pump core mounting flange 3 to the threaded hole in the middle of the mounting base plate 7-1 according to the interface requirements of the housing;

[0028] Install and fix the metal column 7-2 onto the inner threaded hole of the mounting base plate 7-1;

[0029] Fix the mounting base plate 7-1 onto the "L"-shaped mounting bracket 7;

[0030] Install and fix the outlet section 2 onto the positioning cylinder 7-3 on the side plate of the mounting base 7 according to the interface requirements of the shell;

[0031] The water-soluble core mold 7a is installed into the mold through the metal column 7-2. The volute shell outlet of the water-soluble core mold 7a is connected to the outlet section 2, and the pump core mounting shell part is connected to the pump core mounting flange 3. The water-soluble core mold 7a is supported and fixed by the metal column 7-2.

[0032] Install the inlet section 1 onto the upper part of the water-soluble core mold 7a according to the interface requirements of the shell, and fix it with the inlet section 1 positioning connector 7-2a. The inlet section 1 positioning connector 7-2a is fixed to the metal column 7-2 with screws.

[0033] Step 8: Prepare the composite material into a prepreg and cut it according to the structural development diagram;

[0034] Step 9: Lay the cut prepreg according to the direction specified in the drawing, and embed various types of overlapping pieces 6 in the laying process. After laying, fix it with auxiliary silicone outer film 7b. Use autoclave molding process to solidify the main body 5 of the housing to achieve the integrated molding of the fuel pump housing.

[0035] Furthermore, the water-soluble core mold 7a is made of soluble salt, and its mold surface is precision machined to a surface roughness of Ra3.2. The water-soluble core mold 7a is supported and fixed by metal columns 7-2.

[0036] Furthermore, the inner cavity of the inlet section 1, the sealing groove 1-1, and the mounting surface with the system pipeline are designed with high-gloss surfaces and are precision machined; the part of the inlet section 1 that contacts the shell body 5 is designed with a rough surface and is rough machined; the contact surface that connects with the shell body 5 and the system pipeline is designed with a conductive anodized surface; other surfaces can be anodized with sulfuric acid or chromic acid.

[0037] Furthermore, the inner cavity of the outlet section 2, the sealing groove 1-1, and the mounting surface with the system pipeline are designed with high-gloss surfaces and are precision machined; the outer part of the outlet section 2 that contacts the main body 5 is designed with a rough surface and is rough machined; the outlet section 2 is designed as a bent pipe 2-2 structure with a bending radius greater than 1.5d, where d is the diameter of the bent pipe 2-2; the connection surface between the main body 5 and the outlet section 2, and the contact surface between the outlet section 2 and the system pipeline are designed with conductive anodized surfaces, while other surfaces can be anodized with sulfuric acid or chromic acid.

[0038] Furthermore, the inner cavity of the pump core mounting flange 3 and the mounting surface with the pump core structure are designed with a high-gloss finish and are precision machined; the outer part of the pump core mounting flange 3 that contacts the housing body 5 is designed with a rough surface and is rough machined; the contact surface that connects with the housing body 5 and the pump core is designed with a conductive anodized surface, and other surfaces can be anodized with sulfuric acid or chromic acid.

[0039] Compared with the prior art, the present invention has the following technical features:

[0040] This invention effectively solves the practical application problem of composite materials in fuel pump housings of aviation electromechanical systems, paving the way for the large-scale use of composite materials in aviation electromechanical systems, reducing the weight of aviation electromechanical products, and providing a new solution for the lightweighting of aviation electromechanical systems. The application of this invention can significantly reduce the weight of fuel pump products and aircraft, increasing the aircraft's payload or fuel capacity, which is of great significance for improving the combat performance and economic performance of aircraft. Attached Figure Description

[0041] Figure 1This is a schematic diagram of the external structure of the composite housing of the fuel pump;

[0042] Figure 2 This is a schematic diagram of the composite housing structure of the fuel pump;

[0043] Figure 3 This is a schematic diagram showing the shape and features of the inlet section of the composite housing of the fuel pump;

[0044] Figure 4 This is a schematic diagram showing the shape and features of the outlet section of the composite housing of the fuel pump;

[0045] Figure 5 This is a schematic diagram of the external shape of the composite housing molding die for the fuel pump;

[0046] Figure 6 This is a schematic diagram of the composite housing assembly mold structure of the fuel pump. Detailed Implementation

[0047] The composite fuel pump housing structure described in this solution is shown in [link to solution]. Figure 1 The system includes a volute flow channel structure and a mounting support structure, an inlet section 1 located on the upper part of the housing body 5, an outlet section 2 on the side of the housing body 5, a pump core mounting flange 3 connecting the internal pump core structure of the fuel pump, a pump housing mounting flange 4 for installing the fuel pump housing into the system, and an overlap piece 6 laid in the housing body 5 to meet the electrical overlap requirements of the housing. (See attached image.) Figure 2 ,in:

[0048] The main body 5 is a cylindrical component, comprising an upper volute flow channel housing, a middle pump core mounting housing, and a flange in the lower pump housing mounting flange 4. The main body 5 is an integrated structure of the above parts. The upper volute housing is the main flow passage for fuel. After being pressurized by work in the impeller, the fuel flows into the volute housing, where it undergoes further energy conversion before flowing into the outlet section 2. The cross-sectional area of ​​the flow path in the volute casing gradually increases from the inside to the outside of the volute, adapting to the fuel flow rate. The flow path is generally circular, but can also be horseshoe-shaped, rectangular, etc. The wall thickness of the volute casing is generally (3-5) mm. The middle part of the casing body 5 is the pump core mounting casing, which is cylindrical. The inner cavity of the pump core mounting casing matches the outer shape of the pump core part. The wall thickness of the mounting casing is generally (3-4) mm. The lower flange is a ring-shaped symmetrical structure. There are reinforcing ribs on the outer circumference of the lower flange. The number of reinforcing ribs is generally 8-12, evenly distributed on the outer circle. The threaded insert 4-1 is installed inside the reinforcing rib. Its thickness shall not be less than the maximum circumferential size of the threaded insert 4-1. The edges of the reinforcing ribs intersect with the pump core mounting casing and are rounded. For ease of forming, the radius of the rounded corner is generally not less than 3 mm. The main body 5 of the housing is made of composite material. The specific material is selected based on factors such as the product's usage environment, molding process, and cost. For fuel pump housings, carbon fiber cloth / modified epoxy resin prepreg (grade T300 / MT3-UD150) is recommended as the material for the main body 5 of the housing.

[0049] Inlet section 1 is a cylindrical component, see Figure 3 It is connected to the system pipeline at the fuel inlet of the fuel pump, and the fuel in the system flows into the product housing; after the pump core is installed in the housing body 5, the impeller is located in the middle of the inlet section 1 and the volute flow channel housing. The motor in the pump core drives the impeller to rotate, do work on the fuel, and enter the volute flow channel housing under the action of centrifugal force, and finally flow out of the fuel pump from the outlet section 2. The outer wall of the inlet section 1 is provided with a sealing groove 1-1, and a rubber sealing ring is installed in the sealing groove 1-1 to prevent fuel leakage when connected to the system pipeline. The compression of the sealing ring reaches 4% to meet the sealing requirements. The inlet section 1 is provided with an inlet mounting flange 1-2 according to the installation requirements. The shape of the inlet mounting flange 1-2 can be circular, fan-shaped or any other shape as needed. The thickness of the inlet mounting flange 1-2 is generally (3~5) mm. The lower part of the inlet section 1 is inserted into the upper end of the housing body 5, and an outward flange structure 1-3 is provided at the lower end of the inlet section 1 where it connects with the fuel pump housing body 5 to increase the connection strength between the inlet section 1 and the housing body 5 and prevent the inlet section 1 from loosening from the housing body 5. The size of the flange is generally (2~3) mm. The inlet section 1 is made of aluminum alloy, with high processing precision and good electrical connection performance.

[0050] The outlet section 2 has a trumpet-shaped structure and is connected to the outer end of the volute flow channel shell. The diameter of the outlet section 2 gradually decreases from the outer end to the inner end. The outlet section 2 is designed as a bend 2-2, with the axis of the outer end face pointing towards the central axis of the volute flow channel shell. This structural design increases the connection strength between the outlet section 2 and the shell body 5, preventing the outlet section 2 from detaching from the shell body 5. The bending radius of the bend 2-2 is generally greater than 1.5d, where d is the diameter of the bend 2-2. See... Figure 4 The outlet section 2 connects to the system pipeline at the fuel pump outlet. Fuel, pressurized by the fuel pump, flows out of the fuel pump through outlet section 2 and into the system pipeline. Outlet section 2 is equipped with a pressure testing port 2-1, a cylindrical structure with a hollow interior communicating with the inner cavity of outlet section 2. The system's pressure sensor can detect the fuel pressure in outlet section 2 through pressure testing port 2-1 to monitor the product's operating status. An installation flange is located at the connection point between outlet section 2 and the system pipeline. This flange is typically a regular annular structure with 6 or 8 fastening screw holes. The flange thickness is typically (5-10) mm to withstand the high fuel pressure at the fuel pump outlet. A sealing groove 1-1 is located on the end face of the flange, housing a sealing ring. This end-face sealing prevents fuel leakage at the connection point. The compression of the sealing ring is typically 10%-20%. Outlet section 2 is made of aluminum alloy, with high machining precision and good electrical connection performance.

[0051] The pump core mounting flange 3, which connects to the internal pump core structure of the fuel pump, is a cylindrical component located at the bottom end of the main body 5. The inner cavity of the pump core mounting flange 3 is adapted to the shape of the pump core portion installed inside the fuel pump housing, using a clearance fit. The pump core structure can be installed or removed within the mounting flange 3. The inner wall of the pump core mounting flange 3 has high dimensional accuracy, typically grade 7; and a high surface finish, at least Ra1.6, to form a sealing structure with the sealing ring on the pump core structure. The outer wall of the pump core mounting flange 3 is rough, and can also be designed as serrated, to increase the connection strength with the main body 5. The wall thickness of the cylindrical component is not less than 2.5mm to prevent processing deformation. The bottom end face of the pump core mounting flange 3 has 8 to 10 threaded holes, with 1 to 2 holes arranged non-uniformly to prevent errors during pump core structure installation. A weight-reducing groove is designed between every two mounting holes to reduce the weight of the structure. The pump core mounting flange 3 is made of aluminum alloy, with high processing precision and good electrical connection performance.

[0052] The fuel pump housing mounting flange 4, used to install the fuel pump housing into the system, is located on the outside of the lower end of the housing body 5. To minimize the weight of the fuel pump housing, the mounting flange 4 is decomposed into numerous threaded inserts 4-1 and a flange. The flange is integrated with the housing body 5, and its features are described in the housing body 5 section. There are typically 8 to 10 threaded inserts 4-1, evenly distributed in the mounting holes on the lower end face of the mounting flange 4, and embedded in the flange. The inner cavity of the threaded insert 4-1 has an internal thread, and the outer ring has a serrated structure with a stepped structure in the axial direction of the outer ring to prevent the threaded insert 4-1 from dislodging from the flange and rotating. The threaded insert 4-1 is made of structural steel to increase the service life of its internal threads.

[0053] The lap joint 6 is a long strip of metal. It includes a connecting piece connecting the inlet section 1 and the outlet section 2, a connecting piece connecting the outlet section 2 and the pump core mounting flange 3, and a connecting piece connecting the pump core mounting flange 3 and the threaded insert 4-1. The connecting piece is lined within the composite material of the housing body 5. Considering the requirements for laying and forming, the width of the lap joint is generally (3-8) mm, the thickness is (0.4-1) mm, and the length is cut according to actual needs. For lap joints with long distances, the number of lap joints is increased to meet electrical connection performance requirements. The material of the lap joint is generally selected as pure copper or copper alloy with high electrical conductivity.

[0054] II. Design Methods

[0055] Step 1: Design the mold according to the shape and interface dimensions of the fuel pump housing, such as... Figure 5 , Figure 6 As shown; there are two types of molds, including positioning molds and forming molds;

[0056] The positioning mold is an "L"-shaped mounting base 7. A base plate 7-1 is fixedly mounted on the "L"-shaped mounting base 7. The mounting base 7-1 has three rings of positioning holes from the outside to the inside, which are opened according to the shell interface size. These holes are used to position the threaded insert 4-1 on the pump shell mounting flange 4, the threaded hole on the internal pump core mounting flange 3, and the metal column 7-2, respectively. The other end of the metal column 7-2 is connected to the inlet mounting flange 1-2 on the inlet section 1 through a positioning connector 7-2a to ensure the relative position of the inlet mounting flange 1-2 on the inlet section 1. A positioning cylinder 7-3 is provided on the side plate of the "L"-shaped mounting base 7. The positioning cylinder 7-3 is cylindrical, with one end fixed to the side plate of the "L"-shaped mounting base 7 by screws or welding, and the other end has threaded mounting holes. The number and position of the threaded mounting holes are consistent with the mounting holes of the outlet mounting flange 2-3 in the outlet section 2. Four lifting rings are provided on the outer edge of the base plate of the "L"-shaped mounting base 7 for mold handling.

[0057] The molding dies include two types. One is a core mold installed inside the shell structure. Due to the complex internal spiral structure, a water-soluble core mold 7a is used for integral molding. The water-soluble core mold 7a is usually made of soluble salt, and its mold surface is precision machined to achieve a surface roughness of Ra3.2. The water-soluble core mold 7a is supported and fixed by metal columns 7-2. The other molding die is an auxiliary silicone outer film 7b installed outside the shell structure. The auxiliary silicone outer film 7b is generally made of silicone and is shaped according to the external shape of the shell structure. Positioning wedges are inserted between the reinforcing ribs to assist in the molding of the reinforcing ribs; the number of wedges is the same as that of the reinforcing ribs.

[0058] Step 2: Design the shape and installation dimensions of inlet section 1 based on the shape and interface dimensions of the fuel pump housing, and machine it using machining. The inner cavity of inlet section 1, the sealing groove 1-1, and the mounting surface with the system pipeline are designed with a high-gloss finish and precision machined. The outer part of inlet section 1 that contacts the housing body 5 is designed with a rough surface and rough machined to improve the connection strength with the housing body 5. The contact surfaces connecting with the housing body 5 and the system pipeline are designed with conductive anodized surfaces to improve electrical bonding performance. Other surfaces can be anodized with sulfuric acid or chromic acid.

[0059] Step 3: Design the shape and installation dimensions of outlet section 2 based on the shape and interface dimensions of the fuel pump housing, and machine it using machining. The inner cavity, sealing groove, and mounting surface with the system pipeline of outlet section 2 are designed with a high-gloss finish and precision-machined. The outer part of outlet section 2 that contacts the housing body 5 is designed with a rough surface and rough-machined to improve the connection strength with the housing body 5. Outlet section 2 is designed as a bend 2-2 to increase the connection strength with the housing body 5 and prevent outlet section 2 from detaching from the housing body 5. The bending radius of bend 2-2 is generally greater than 1.5d, where d is the diameter of bend 2-2. The connection surface between the housing body 5 and outlet section 2, and the contact surface between outlet section 2 and the system pipeline are designed as conductive anodized surfaces to improve electrical bonding performance. Other surfaces can be anodized with sulfuric acid or chromic acid.

[0060] Step 4: Design the shape and installation dimensions of the pump core mounting flange 3 according to the shape and interface dimensions of the fuel pump housing, and machine it using machining. The inner cavity of the pump core mounting flange 3 and the mounting surface with the pump core structure are designed with a high-gloss finish and precision machined; the outer part of the pump core mounting flange 3 that contacts the housing body 5 is designed with a rough surface and rough machined to improve the connection strength with the housing body 5. The contact surfaces connecting the housing body 5 and the pump core are designed with conductive anodized surfaces to improve electrical bonding performance; other surfaces can be anodized with sulfuric acid or chromic acid.

[0061] Step 5: Design the shape and installation dimensions of the threaded insert 4-1 in the pump housing mounting flange 4 according to the shape and interface dimensions of the fuel pump housing, and machine it using machining. The inner cavity of the threaded insert 4-1 has a threaded structure for connection and fastening; the outer surface of the threaded insert 4-1 has a serrated and stepped structure to prevent the threaded insert 4-1 from coming out of the housing body 5. The threaded insert 4-1 is made of structural steel and its surface is chemically anodized.

[0062] Step 6: Cut overlapping pieces 6 from the profile according to the shape and size of the fuel pump housing. The overlapping pieces 6 include three specifications: a connecting piece for connecting the inlet section 1 and the outlet section 2, a connecting piece for connecting the outlet section 2 and the pump core mounting flange 3, and a connecting piece for connecting the pump core mounting flange 3 and the threaded insert 4-1. The overlapping pieces 6 of different lengths and widths should be cut according to the distance between the above components and the shape of the housing. The overlap length between the overlapping piece 6 and each component should not be less than the width of the overlapping piece.

[0063] Step 7: Assemble using the mold, specifically as follows:

[0064] Install and fix the threaded insert 4-1 onto the outer threaded hole of the mounting base plate 7-1;

[0065] Install and fix the pump core mounting flange 3 to the threaded hole in the middle of the mounting base plate 7-1 according to the interface requirements of the housing;

[0066] Install and fix the metal column 7-2 onto the inner threaded hole of the mounting base plate 7-1;

[0067] Fix the mounting base plate 7-1 onto the "L"-shaped mounting bracket 7;

[0068] Install and fix the outlet section 2 onto the positioning cylinder 7-3 on the side plate of the mounting base 7 according to the interface requirements of the shell;

[0069] The water-soluble core mold 7a is installed into the mold through the metal column 7-2. The volute shell outlet of the water-soluble core mold 7a is connected to the outlet section 2, and the pump core mounting shell part is connected to the pump core mounting flange 3. The water-soluble core mold 7a is supported and fixed by the metal column 7-2.

[0070] Install the inlet pipe 1 onto the upper part of the water-soluble core mold 7a according to the interface requirements of the shell, and fix it with the inlet section 1 positioning connector 7-2a. The inlet section 1 positioning connector 7-2a is fixed to the metal column 7-2 with screws.

[0071] Laser trackers are used for installation during the assembly of each part. The positional accuracy of the positioning holes is ≤ ±0.1mm. The manufacturing dimensional tolerances of the tooling parts shall comply with GB / T1804-m.

[0072] Step 8: Prepare the composite material into a prepreg and cut it according to the structural development diagram;

[0073] Step 9: Lay the cut prepreg according to the direction specified in the drawing, and embed various types of overlapping pieces 6 in the laying process. After laying, fix it with auxiliary silicone outer film 7b. Use autoclave molding process to solidify the main body 5 of the housing to achieve the integrated molding of the fuel pump housing.

[0074] III. Combining structural analysis characteristics

[0075] The composite-based fuel pump housing structure and its design method provided in this solution have the following characteristics:

[0076] The main structure of the fuel pump housing is made of composite material with high specific strength, high specific modulus and low density. While meeting the housing performance requirements, the weight of the housing is reduced to the minimum, which is the design direction of lightweight composite products.

[0077] For threaded connections, high-precision mounting parts, and system connection flanges, metal materials are used for design and molding. The strength, conductivity, and dimensional stability of metal are used to meet the requirements of threaded connection strength, electrical lap joint, and assembly dimensional accuracy, thus eliminating the shortcomings of composite materials in the above-mentioned performance aspects.

[0078] The above-mentioned metal processing parts are pre-embedded before the composite shell is formed, and the bonding between the metal and the composite is achieved during the curing and forming process of the composite parts;

[0079] The selected composite material has similar physical properties, such as the coefficient of thermal expansion, to the embedded metal, which ensures that the metal parts and the composite shell can maintain good connection characteristics under different environments.

[0080] Metal embedded parts, taking into account their own structural characteristics, are designed with flanged structures, bent structures, protruding structures, sawtooth structures, and stepped structures to achieve a reliable connection with the composite material and prevent them from coming off the composite material body.

[0081] Before the composite structure is formed, an adhesive film is laid on the metal bonding surface. When the composite is cured, the adhesive film melts and flows, which can fully fill the gaps in the bonding area and achieve the density of the adhesive layer.

[0082] Apply high-temperature resistant rubber sealant to the joints of composite and metal structures to fully impregnate and fill the gaps and improve the sealing performance of the joints.

[0083] By combining molds and tooling, we can ensure the accurate positioning of each component and ensure that the shell structure meets the interface and dimensional requirements.

[0084] Although the main body of the shell is made of non-conductive composite material, the electrical connection performance requirements of each part of the shell structure are achieved by connecting the various interface flanges through pre-embedded lap joints in the main body of the composite material.

[0085] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A fuel pump housing structure based on composite materials, characterized in that, Includes a housing body (5) and an inlet section (1) located on the upper part of the housing body (5), an outlet section (2) on the side of the housing body (5), a pump core mounting flange (3) connecting the internal pump core structure of the fuel pump, a pump housing mounting flange (4) realizing the fuel pump housing, and an overlapping piece (6) laid in the housing body (5), wherein: The main body of the housing (5) is a cylindrical component, including the upper volute flow channel housing, the middle pump core mounting housing and the flange in the lower pump housing mounting flange (4); the middle part of the main body of the housing (5) is the pump core mounting housing, which is cylindrical. The inner cavity of the pump core mounting housing is adapted to the outer shape of the pump core part. The lower flange is a ring-shaped symmetrical structure. The outer circumference of the lower flange is provided with reinforcing ribs. The reinforcing ribs are fitted with threaded inserts (4-1). The edges of the reinforcing ribs that intersect with the pump core mounting housing are provided with rounded corners. The inlet section (1) is a cylindrical component that is connected to the system pipeline at the fuel inlet of the fuel pump and draws fuel from the system into the product housing. When the pump core is installed in the housing body (5), the impeller is located in the middle of the inlet section (1) and the volute flow channel housing. A sealing groove (1-1) is provided on the outer wall of the inlet section (1), and a rubber sealing ring is installed in the sealing groove (1-1). An inlet mounting flange (1-2) is provided on the outside of the inlet section (1). The lower part of the inlet section (1) is inserted into the upper end of the housing body (5), and an outward flange structure (1-3) is provided at the junction of the lower end of the inlet section (1) and the fuel pump housing body (5). The outlet section (2) has a trumpet-shaped structure and is connected to the outer end of the volute flow channel housing. The diameter of the outlet section (2) gradually decreases from the outer end to the inner end. The axis of the outer end face of the outlet section (2) points to the central axis of the volute flow channel housing. The outlet section (2) is connected to the system pipeline at the outlet of the fuel pump. The fuel that has been boosted by the fuel pump flows out of the fuel pump through the outlet section (2) and into the system pipeline. The outlet section (2) is provided with a pressure measuring port (2-1). The pressure measuring port (2-1) has a columnar structure. The interior of the pressure measuring port (2-1) is hollow and communicates with the inner cavity of the outlet section (2). The pressure sensor is used to sense the fuel pressure in the outlet section (2) through the pressure measuring port (2-1). The pump core mounting flange (3) is a cylindrical component located at the bottom of the housing body (5). The inner cavity of the pump core mounting flange (3) is adapted to the shape of the pump core part installed inside the fuel pump housing, and a clearance fit is adopted. The pump casing mounting flange (4) is located on the outside of the lower end of the housing body (5). The pump casing mounting flange (4) includes multiple threaded inserts (4-1) and a flange. The flange adopts an integrated design with the housing body (5). The threaded inserts (4-1) are evenly distributed in the assembly holes on the lower end face circumference of the pump casing mounting flange (4) and are embedded in the flange. The inner cavity of the threaded insert (4-1) is internally threaded, the outer ring is a sawtooth structure, and a stepped structure is provided in the axial direction of the outer ring. The overlapping piece (6) is a long strip of metal. The overlapping piece (6) includes a connecting piece connecting the inlet section (1) and the outlet section (2), a connecting piece connecting the outlet section (2) and the pump core mounting flange (3), and a connecting piece connecting the pump core mounting flange (3) and the threaded insert (4-1). The connecting piece is lined into the composite material of the housing body (5).

2. The composite-based fuel pump housing structure according to claim 1, characterized in that, After being pressurized by the impeller, the fuel flows into the volute casing. After further energy conversion in the volute casing, it flows into the outlet section (2). The cross-sectional area of ​​the volute casing gradually increases from the inside to the outside of the volute, which is adapted to the flow rate of the fuel. The cross-sectional area is circular, horseshoe-shaped, or rectangular, and the wall thickness of the volute casing is 3-5 mm.

3. The composite-based fuel pump housing structure according to claim 1, characterized in that, The outlet section (2) is connected to the system pipeline with an installation flange. The installation flange is connected to the system pipeline and has a regular ring structure. The thickness of the installation flange is generally 5 to 10 mm. A sealing groove (1-1) is provided on the end face of the installation flange, and a sealing ring is installed inside. The end face sealing method is used to prevent fuel leakage at the connection. The compression of the sealing ring is generally 10% to 20%.

4. The fuel pump housing structure based on composite materials according to claim 1, characterized in that, The inner wall dimensional accuracy of the pump core mounting flange (3) is grade 7; the surface finish is at least Ra1.6; the outer wall of the pump core mounting flange (3) is rough or designed as a sawtooth shape; the bottom end face of the pump core mounting flange (3) is provided with threaded holes, of which 1 to 2 holes are arranged in a non-uniform manner, and a weight reduction groove is designed between each pair of mounting holes.

5. The fuel pump housing structure based on composite materials according to claim 1, characterized in that, The width of the lap joint is 3-8mm, the thickness is 0.4-1mm, and the length is cut according to actual needs; the material of the lap joint is pure copper or copper alloy.

6. A design method for a fuel pump housing structure based on composite materials as described in claim 3, characterized in that, include: Step 1: Design the mold according to the shape and interface size of the fuel pump housing. There are two types of molds: positioning mold and forming mold. The positioning mold is an "L"-shaped mounting base (7). A mounting base plate (7-1) is fixed on the "L"-shaped mounting base (7). The mounting base plate (7-1) has multiple positioning holes from the outside to the inside, which are opened according to the shell interface size. They are used to position the threaded insert (4-1) on the pump shell mounting flange (4), the threaded hole on the internal pump core mounting flange (3), and the metal column (7-2). The other end of the metal column (7-2) is connected to the inlet mounting flange (1-2) on the inlet section (1) through the positioning connector (7-2a). A positioning cylinder (7-3) is provided on the side plate of the mounting base (7). The positioning cylinder (7-3) is cylindrical. One end is fixed to the side plate of the "L"-shaped mounting base (7) by screwing or welding. The other end is provided with threaded mounting holes. The number and position of the threaded mounting holes are consistent with the mounting holes of the outlet mounting flange (2-3) in the outlet section (2). The molding mold includes two types: one is a core mold installed inside the shell structure, which adopts a water-soluble core mold (7a) integral molding process; the other molding mold is an auxiliary silicone outer film (7b) installed outside the shell structure. Step 2: Design the shape and installation dimensions of the inlet section (1) according to the shape and interface dimensions of the fuel pump housing, and process it by machining. Step 3: Design the shape and installation dimensions of the outlet section (2) according to the shape and interface dimensions of the fuel pump housing, and process it by machining. Step 4: Design the shape and installation dimensions of the pump core mounting flange (3) according to the shape and interface dimensions of the fuel pump housing, and process it by machining. Step 5: Design the shape and installation dimensions of the threaded insert (4-1) in the pump housing mounting flange (4) according to the shape and interface dimensions of the fuel pump housing, and process it by machining. Step 6: Cut overlapping pieces (6) from the profile according to the shape and size of the fuel pump housing. The overlapping pieces (6) include three specifications: a connecting piece for connecting the inlet section (1) and the outlet section (2), a connecting piece for connecting the outlet section (2) and the pump core mounting flange (3), and a connecting piece for connecting the pump core mounting flange (3) and the threaded insert (4-1). Step 7: Assemble using the mold, specifically as follows: Install and fix the threaded insert (4-1) onto the outer threaded hole of the mounting base plate (7-1); Install and fix the pump core mounting flange (3) onto the threaded hole in the middle of the mounting base plate (7-1) according to the interface requirements of the housing; Install and fix the metal column (7-2) onto the inner threaded hole of the mounting base plate (7-1); Fix the mounting base plate (7-1) onto the "L"-shaped mounting bracket (7); Install and fix the outlet section (2) onto the positioning cylinder (7-3) on the side plate of the mounting base (7) according to the interface requirements of the shell; The water-soluble core mold (7a) is installed into the mold through the metal column (7-2). The volute shell outlet of the water-soluble core mold (7a) is connected to the outlet section (2). The pump core mounting shell part is connected to the pump core mounting flange (3). The water-soluble core mold (7a) is supported and fixed by the metal column (7-2). Install the inlet section (1) onto the upper part of the water-soluble core mold (7a) according to the interface requirements of the shell, and fix it with the inlet section (1) positioning connector (7-2a). The inlet section (1) positioning connector (7-2a) is fixed to the metal column (7-2) by screws. Step 8: Prepare the composite material into a prepreg and cut it according to the structural development diagram; Step 9: Lay the cut prepreg in the direction specified in the drawing, and embed various types of overlapping pieces (6) in the laying. After laying, fix it with auxiliary silicone outer film (7b). Use autoclave molding process to solidify the main body of the housing (5) to achieve integrated molding of the fuel pump housing.

7. The composite-based fuel pump housing design method according to claim 6, characterized in that, The water-soluble core mold (7a) is made of soluble salt, and its mold surface is precision machined to a surface roughness of Ra3.

2. The water-soluble core mold (7a) is supported and fixed by metal columns (7-2).

8. The composite-based fuel pump housing design method according to claim 6, characterized in that, The inner cavity of the inlet section (1), the sealing groove (1-1) and the mounting surface with the system pipeline are designed with high gloss surface and are precision machined; the part of the inlet section (1) that contacts the shell body (5) is designed with rough surface and is rough machined; the contact surface that connects with the shell body (5) and the system pipeline is designed with conductive anodized surface; other surfaces can be anodized with sulfuric acid or chromic acid.

9. The composite-based fuel pump housing design method according to claim 6, characterized in that, The inner cavity of the outlet section (2), the sealing groove (1-1), and the mounting surface with the system pipeline are designed with high gloss surfaces and are precision machined. The part of the outlet section (2) that contacts the shell body (5) is designed with a rough surface and is rough machined. The outlet section (2) is designed with a bent pipe (2-2) structure. The bending radius of the bent pipe (2-2) is greater than 1.5d, where d is the diameter of the bent pipe (2-2). The connection surface between the shell body (5) and the outlet section (2) and the contact surface between the outlet section (2) and the system pipeline are designed with conductive anodized surfaces. Other surfaces can be anodized with sulfuric acid or chromic acid.

10. The composite-based fuel pump housing design method according to claim 6, characterized in that, The inner cavity of the pump core mounting flange (3) and the mounting surface with the pump core structure are designed to have a high gloss surface and are precision machined. The part of the pump core mounting flange (3) that contacts the housing body (5) is designed to have a rough surface and is rough machined. The contact surface that connects with the housing body (5) and the pump core is designed to have a conductive anodized surface. Other surfaces can be anodized with sulfuric acid or chromic acid.

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