Large-displacement oil pump and manufacturing process thereof

Abstract

The invention discloses a large-displacement oil pump which comprises a pump body. The pump cover is arranged on the pump body and used for sealing the pump body; the main shaft is inserted into the pump body and used for being connected with an external power source and driving the inner rotor to rotate; the inner rotor is arranged in the pump body and sleeves the main shaft; the outer rotor is arranged in the pump body, arranged on the inner rotor in a sleeving mode and matched with the inner rotor to suck in and press out engine oil. The limiting spring is arranged in the pump body in a sliding manner; the valve element is located in the pump body and used in cooperation with the limiting spring. The steel ball is arranged in the pump body and located between the bowl-shaped plug and the safety valve spring. The engine oil pump has the advantages that displacement and heat dissipation are optimized, the service life of an engine is prolonged, rotor performance is enhanced, a flow channel is optimized, displacement performance is greatly improved, product quality is improved, the problems of leakage and faults caused by improper matching are reduced, and the operation stability of the engine oil pump is greatly improved.

Description

Technical Field

[0001] The present invention relates to an oil pump, and more particularly to a large-displacement oil pump and its manufacturing process. Background Art

[0002] At present, with the booming development of the global automotive industry, environmental protection and energy conservation have become the core themes of the industry's development. As fuel consumption regulations in various countries become increasingly stringent, automotive manufacturers are facing unprecedented pressure and urgently need to reduce automotive energy consumption and improve fuel economy through technological innovation. As the core component of an automobile, the automotive engine is accelerating towards a more high-speed and energy-efficient direction. As a key component of the engine lubrication system, the performance of the oil pump directly affects the working efficiency, reliability, and durability of the engine. The research and development of high-performance oil pumps have become a key area of technological innovation for major automobile manufacturers; On the one hand, the oil pumps in the prior art are difficult to meet the continuously improving performance requirements of modern automotive engines. Insufficient flow rate is one of the more prominent problems. For some models, the oil pumps installed cannot provide sufficient oil flow rate when the engine is running at high speed, resulting in insufficient lubrication of various engine components, increasing frictional losses, not only reducing the power output of the engine but also causing problems such as engine overheating, seriously affecting the service life and reliability of the engine; on the other hand, developing high-performance oil pumps faces huge challenges. Taking the manufacture of the pump body of the NPR03LB oil pump as an example, its complex structural design places extremely high requirements on the die-casting process. When facing a pump body with high precision and complex structure, the traditional die-casting process is difficult to ensure the dimensional accuracy and internal quality of the product, and defects such as pores and shrinkage porosity are likely to occur, affecting the strength and sealing performance of the pump body, and thus reducing the overall performance of the oil pump; in addition, the machining accuracy and surface quality of the pump body are also crucial for the working efficiency and service life of the oil pump. The traditional machining process has certain limitations in precision control and surface treatment and is difficult to meet the manufacturing requirements of high-performance oil pumps.

[0003] Therefore, those skilled in the art are committed to providing a large-displacement oil pump and its manufacturing process that can effectively solve the above technical problems. Summary of the Invention

[0004] In view of the above-mentioned defects of the prior art, the technical problem to be solved by the present invention is to provide a large-displacement oil pump and its manufacturing process that can effectively solve the above technical problems.

[0005] To achieve the above object, the present invention provides a large-displacement oil pump, including a pump body; a pump cover, disposed on the pump body for closing the pump body; a main shaft, inserted in the pump body for connecting to an external power source and driving the inner rotor to rotate; Inner rotor, which is arranged inside the pump body and sleeved on the main shaft; Outer rotor, which is arranged inside the pump body and sleeved on the inner rotor, and cooperates with the inner rotor to suck and press out engine oil; Limit spring, which is slidably arranged inside the pump body; Spool valve, which is located inside the pump body and cooperates with the limit spring; Steel ball, which is arranged inside the pump body and located between the bowl-shaped plug and the safety valve spring.

[0006] Preferably, it further includes a belt pulley, which is arranged outside the pump body and sleeved on the main shaft, and is used to drive the main shaft to rotate; Belt pulley rib, which is arranged between the pump cover and the belt pulley and is used for axially limiting the belt pulley.

[0007] Preferably, it includes pump body processing Blank making: The pump body blank is manufactured by die casting process; Rough machining: Deburr the pump body blank, and then mill the mounting surface by milling; drill the oil passage holes; Finish machining: Finish milling and grinding the inner and outer contours of the pump body, and clean the machined pump body; Pump cover processing Blank preparation: The pump cover blank is made by casting or forging; Processing and forming: First mill the plane of the pump cover; then drill holes, and grind or polish the sealing surface that cooperates with the pump body; Quality inspection: Check the dimensional accuracy and surface quality of the pump cover.

[0008] Preferably, the specific steps of manufacturing the pump body blank by die casting process include: 1: Mold design and pretreatment Mold design: Conduct three-dimensional modeling of the mold, and eliminate defects by simulating the die casting process; Mold pretreatment: Select steel material, first perform quenching treatment, heat it to 1020 - 1050 °C, keep it warm for 2 - 3 hours, then perform tempering treatment at 550 - 580 °C, temper 3 times, keep it warm for 2 - 3 hours each time, and before use, perform nitriding treatment on the mold surface, the nitriding temperature is 500 - 550 °C, and the nitriding time is 20 - 30 hours; 2: Melting and alloy optimization Material selection: Select high-strength alloy, control the iron element content within 0.15% - 0.2%, and control the copper element content within 0.05; Melting process: The electromagnetic induction furnace is used for melting. The furnace temperature is raised to 720 - 750 °C. When the alloy is completely melted, 0.03% - 0.05% by mass of strontium is added as a modifier for modification treatment. After stirring evenly to refine the grains, a refining agent is used for degassing and slag removal treatment. Argon is introduced with the flow rate controlled at 0.1 - 0.2 m³ / h and the treatment time is 10 - 15 minutes to remove the gas and inclusions in the molten alloy; 3: Vacuum die-casting Equipment preparation: Before die-casting, the mold cavity is evacuated to pump out the air inside the cavity so that the internal air pressure of the cavity reaches 5 - 8 kPa; Die-casting parameter control: The injection speed is controlled in sections. The initial filling speed is 0.3 - 0.5 m / s to enable the molten alloy to fill the cavity smoothly and avoid turbulence and air entrainment. The filling speed in the later stage is increased to 3 - 5 m / s so that the molten alloy can fill every corner of the cavity. The injection pressure is 30 - 50 MPa in the initial filling stage and increases to 80 - 120 MPa in the later filling stage. The holding pressure time is adjusted according to the average wall thickness of the pump body. When the wall thickness is less than 5 mm, the holding pressure time is 10 - 15 s; when the wall thickness is between 5 - 10 mm, the holding pressure time is 15 - 25 s; when the wall thickness is greater than 10 mm, the holding pressure time is 25 - 40 s; 4: Rapid cooling and demolding Cooling system optimization: A cooling water channel system is adopted inside the mold. The inlet water temperature is controlled at 20 - 25 °C and the water flow speed is 1 - 2 m / s; 5: Demolding treatment: After the casting is cooled to 200 - 250 °C, a demolding agent is used to assist demolding. The demolding agent is evenly sprayed on the mold surface at a pressure of 0.3 - 0.5 MPa to reduce the friction between the casting and the mold. After demolding, the casting is preliminarily cleaned to remove the residual demolding agent and burrs on the surface.

[0009] Preferably, after the demolding treatment, it further includes: Stress relief treatment: The pump body blank after die-casting is subjected to stress relief annealing. The blank is put into a heating furnace and heated to 280 - 320 °C at a heating rate of 50 - 100 °C per hour, held for 2 - 3 hours, and then cooled to room temperature with the furnace to eliminate the residual stress inside the casting; Quality inspection: Non-destructive testing technology is adopted. The detection voltage is 100 - 150 kV and the detection time is 2 - 5 minutes; ultrasonic flaw detection is carried out with the probe frequency of 2 - 5 MHz to comprehensively detect the pump body blank and check whether there are defects inside; at the same time, a three-coordinate measuring instrument is used to measure the dimensions of the pump body blank. For the unqualified blanks, repair or scrapping is taken.

[0010] Preferably, the blank preparation for the pump cover machining: The pump cover blank is made by casting or forging, specifically including: Material preparation: Select metal powder with a particle size of 50 - 150 microns and prepare a polymer resin binder according to a mass ratio of metal powder to binder of 10:1. At the same time, prepare a water-soluble gypsum material for mold manufacturing. Mold design and fabrication: Construct a mold model according to the design drawing of the pump cover, import the designed model into an FDM printer, and use the water-soluble gypsum material to print the mold. After printing, process the mold with a grinding machine to make the surface roughness of the mold reach Ra0.8 - Ra1.6μm, and control the dimensional accuracy within the range of ±0.1mm. Mixing and filling: Put the metal powder and binder into a stirring device and mix them at a stirring speed of 300 - 500 revolutions per minute for 15 - 20 minutes. Then fill the mixed material into the printed mold. When filling, turn on the vibration assistance device with a vibration frequency set at 50 - 80Hz to make the material fill tightly. Curing and forming: Place the mold filled with the material in a hot air circulation curing furnace, increase the temperature to 150 - 180℃ at a heating rate of 5 - 10℃ / minute, and keep it warm and cured for 30 - 45 minutes at this temperature. During the curing process, the binder plays a role in bonding the metal powder to promote the preliminary forming of the pump cover blank. After curing, take out the mold from the curing furnace and let it cool naturally to room temperature. Demolding and cleaning: When the mold cools to room temperature, immerse it in warm water at 40 - 50℃. Due to the characteristics of the water-soluble gypsum material, the mold will gradually dissolve within 20 - 30 minutes to complete demolding. After demolding, wash the pump cover blank with a high-pressure water gun at a water pressure of 3 - 5MPa to remove the residual mold material and impurities on the surface. Debinding treatment: Put the washed pump cover blank into a debinding device with a temperature control device, add acetone as an organic solvent, set the debinding temperature at 50 - 60℃, and the debinding time at 60 - 90 minutes. During the debinding process, good ventilation needs to be maintained. Sintering densification: Put the debound pump cover blank into a high-temperature sintering furnace, introduce nitrogen with a purity of 99.99% as a protective atmosphere, increase the temperature to 1200 - 1300℃ at a heating rate of 10 - 15℃ / minute, and keep it warm and sintered for 60 - 90 minutes at this temperature.

[0011] Preferably, it also includes the processing steps for the inner rotor as follows: After cutting the raw material into a blank, put it into a vacuum heating furnace and keep it at 600 - 700℃ for 1 - 2 hours for stress relief annealing to eliminate the residual processing stress. Irregular hole machining: The laser-electrolytic hybrid machining technology is adopted. First, a pre-hole is machined in the center area of the blank using a high-energy pulsed laser. The laser pulse energy is controlled at 10 - 20 joules, and the pulse frequency is 50 - 100 Hz. Subsequently, the blank is placed in the electrolyte, and the shaft hole is further precisely formed through electrolytic machining. The machining voltage is maintained at 10 - 15 volts, and the current density is 10 - 15 A / cm², ensuring that the shaft hole accuracy reaches ±0.005 mm, and the surface roughness Ra is 0.2 - 0.4 μm. Tooth profile machining: The electro-discharge milling process is used. The electrode movement trajectory is controlled by numerical control programming to simulate the tooth profile for milling. During the machining process, the discharge energy is controlled at 0.1 - 0.3 joules, and the pulse width is 10 - 20 μs. Surface strengthening treatment: The ion implantation technology is adopted to implant nitrogen ions into the surface of the inner rotor. The implantation energy is 80 - 120 keV, and the implantation dose is 1×10¹ 7 - 3×10¹ 7 ions / cm²; a modified layer is formed on the surface.

[0012] Preferably, it further includes the processing steps for the outer rotor as follows: Raw material forming: The hot pressing forming process is adopted. The sheet is heated to 450 - 500 °C, placed in the mold, and held under pressure of 50 - 80 MPa for 5 - 10 minutes, and then cooled to room temperature to form the basic shape of the outer rotor. Precision machining of the inner ring: An ultrasonic vibration device is installed on the grinding equipment with a vibration frequency of 20 - 30 kHz and an amplitude of 10 - 20 μm. The inner ring is machined by grinding wheel grinding. The grinding parameters are grinding speed of 30 - 40 m / s and feed rate of 0.01 - 0.03 mm / r. The size accuracy of the inner ring is ±0.01 mm, and the surface roughness Ra is 0.4 - 0.8 μm. Surface treatment: A ceramic oxide film is formed on the surface of the aluminum alloy outer rotor. The electrolyte, treatment voltage is 300 - 400 volts, and the treatment time is 15 - 25 minutes. The thickness of the formed oxide film is 10 - 20 μm, and the hardness is HV500 - HV800.

[0013] Preferably, it further includes the processing steps for the main shaft: Blanking and rough machining: Select the raw material, cut it into the blank with the required length, and perform rough turning on the lathe to machine the basic shape of the main shaft. Milling the keyway on the milling machine for connection with the inner rotor and the pulley; drilling the center hole; Heat treatment and finish machining: Perform heat treatment on the main shaft; Flaw detection: Adopt non-destructive flaw detection to check whether there are defects inside the main shaft.

[0014] Preferably, it further includes pulley machining Blank manufacturing: The blank of the pulley is made by casting or forging methods; Machining: Turning the outer circle and inner hole of the pulley on a lathe; Milling the pulley groove on a milling machine; Drilling bolt holes and positioning holes; Surface treatment: Treat the surface of the pulley; Spool machining: Select a metal material, machine the basic shape of the spool by turning, and then perform grinding to ensure its dimensional accuracy and surface finish, enabling it to move flexibly in the oil passage; Steel ball machining: Machine using a spherical machining device and perform surface polishing after machining; Spring machining: According to the design requirements, select spring wire and wind it into a spring of the required shape using a winding machine; Heat-treat the spring to adjust its elastic coefficient; Then perform shaping treatment.

[0015] The beneficial effects of the present invention are as follows: The present invention provides a large-displacement oil pump and its manufacturing process, which show significant advantages in dimensions such as product performance, manufacturing process, market, and economic benefits, specifically as follows: 1) Optimize displacement and heat dissipation to ensure stable engine operation: By optimizing the design of the inner and outer rotors and the pump chamber, the problems of unqualified oil pump displacement and high overall engine temperature are solved. The optimized rotor and pump chamber have a better fit, improving the oil suction and discharge efficiency and reducing friction losses and heat generation caused by insufficient lubrication. In practical applications, it can ensure the stable operation of the engine during long-term high-load operation and extend the service life of the engine; 2) Enhance rotor performance to meet the requirements of different working conditions: The rotor in the pump chamber is made of high-density metallurgical materials, optimizing the meshing linearity, improving the rotor strength, wear resistance, and sealing performance, and providing reliable power for the oil suction performance; This enables the engine to obtain sufficient oil supply under different working conditions, improving the working efficiency of the engine; For example, during different stages such as engine startup, acceleration, and high-speed operation, the oil pump can stably provide an appropriate oil flow rate to ensure good lubrication of all engine components; 3) Optimize the flow path to significantly improve the displacement performance: Optimize the design of the internal lubricating oil flow path in the pump body, reduce the oil path resistance, increase the oil flow rate and flow, ensure good lubrication and cooling of the engine, and improve the overall performance of the engine.

[0016] 4) Optimization of the pump body manufacturing process to improve product quality: The pump body is made by die-casting process. Strict control is exercised in various links such as mold design and pretreatment, melting and alloy optimization, vacuum die-casting, rapid cooling and demolding, and subsequent stress relief treatment and quality inspection. The mold is treated by quenching, tempering, and nitriding, which improves its hardness, wear resistance, and thermal fatigue performance; high-strength alloy is selected and modified and degassed and slag-removed to improve the quality of the molten alloy; vacuum die-casting effectively reduces the internal porosity and looseness defects of the casting, and precise control of die-casting parameters ensures the quality of the casting. Through these processes, the product quality is effectively controlled, defects such as porosity and shrinkage porosity are reduced, the strength and sealing performance of the pump body are ensured, and the product reliability is improved.

[0017] 5) Fine machining of components to ensure fitting accuracy: The machining processes of components such as the pump cover, inner rotor, outer rotor, and main shaft are fine. From blank preparation to forming machining and then to surface treatment, the dimensional accuracy and surface quality are strictly controlled in each link, improving the overall performance of the oil pump. During the assembly process, the adaptability of the components is better, reducing leakage and failure problems caused by improper fitting, and greatly improving the operating stability of the oil pump. Brief Description of the Drawings

[0018] Figure 1 is a three-dimensional structural schematic diagram of the large-displacement oil pump in the present invention.

[0019] Figure 2 is another three-dimensional structural schematic diagram of the oil pump.

[0020] Figure 3 is a structural schematic diagram without the pulley and pulley flange installed.

[0021] Figure 4 is a structural schematic diagram of the pump cover.

[0022] Figure 5 is a structural schematic diagram of the large-displacement oil pump without the pump cover installed.

[0023] Figure 6 is a formal structural schematic diagram of the oil pump.

[0024] Figure 7 is Figure 6 the sectional structural schematic diagram in the A-A direction in

[0025] Figure 8 is Figure 6 the top view structural schematic diagram of

[0026] Figure 9 is Figure 8 the sectional structural schematic diagram in the B-B direction in

[0027] Figure 10 is Figure 8 the sectional structural schematic diagram in the C-C direction in Detailed implementation mode

[0028] The present invention will be further described below in conjunction with the accompanying drawings and embodiments: In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. In addition, the terms "first", "second", "third" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0029] In the description of the present invention, it should be noted that unless otherwise clearly specified and defined, the terms "installation", "setting", "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0030] As Figures 1 to 10 shown, a large-displacement oil pump includes a pump body 1; A pump cover 2 is arranged on the pump body 1 and used to close the pump body 1; A main shaft 6 is inserted on the pump body 1 and used to connect with an external power source and drive the inner rotor 7 to rotate; An inner rotor 7 is arranged in the pump body 1 and sleeved on the main shaft 6; An outer rotor 8 is arranged in the pump body 1 and sleeved on the inner rotor 7, and is used to cooperate with the inner rotor 7 to suck and press out oil; A limit spring 13 is slidably arranged in the pump body 1; A valve core 14 is located in the pump body 1 and is used in cooperation with the limit spring 13; A steel ball 11 is arranged in the pump body 1 and is located between the bowl-shaped plug 10 and the safety valve spring 12.

[0031] In the present invention, the oil pump further includes A belt pulley 20 is arranged outside the pump body 1 and sleeved on the main shaft 6, and is used to drive the main shaft 6 to rotate; a belt pulley edge 21 is arranged between the pump cover 2 and the belt pulley 20 and is used to axially limit the belt pulley 20.

[0032] The manufacturing process of the large-displacement oil pump includes Processing of the pump body 1 Blank manufacturing: The pump body blank is manufactured by die-casting process; Rough machining: Deburr the pump body 1 blank, and then mill the mounting surface to make the surface flat; Drill the oil passage holes to provide a channel for subsequent oil flow.

[0033] Finish machining: Adopt high-precision machining to finish milling and grinding the inner and outer contours of the pump body 1, strictly control the dimensional accuracy and surface roughness to ensure the fitting accuracy with other parts; At the same time, finely polish the oil flow passage to optimize its internal flow passage structure and reduce the oil flow resistance.

[0034] Clean the machined pump body 1 to remove machining residues; Use equipment such as a coordinate measuring machine to detect key dimensions and geometric tolerances to ensure compliance with design requirements.

[0035] Manufacturing of pump cover 2 Blank preparation: The pump cover blank is made by casting or forging; Machining and forming: First mill the plane of the pump cover 2 to ensure its flatness; Then drill holes (bolt holes, positioning pin holes, etc.) to ensure the connection accuracy with the pump body; Grind or polish the sealing surface that fits with the pump body 1 to improve the sealing performance.

[0036] Quality inspection: Check the dimensional accuracy and surface quality of the pump cover. Focus on detecting the flatness and smoothness of the sealing surface.

[0037] The specific steps of manufacturing the pump body 1 blank by die-casting process include: 1: Mold design and pretreatment Mold design: Conduct three-dimensional modeling of the mold. Specifically, use computer-aided design (CAD) and simulation software to simulate the die-casting process to eliminate defects (such as air holes, shrinkage porosity, etc.); Optimize the mold structure and the layout of the gate and overflow groove.

[0038] Mold pretreatment: Select steel material (H13 high-quality mold), first perform quenching treatment, heat to 1020 - 1050 °C, hold for 2 - 3 hours, and then perform tempering treatment at 550 - 580 °C, temper 3 times, each time holding for 2 - 3 hours to improve the hardness, wear resistance and thermal fatigue performance of the mold. Before use, perform nitriding treatment on the mold surface, the nitriding temperature is 500 - 550 °C, and the nitriding time is 20 - 30 hours; Enhance the anti-adhesion of the mold surface, reduce the friction between the casting and the mold, facilitate the demolding of the casting, and improve the service life of the mold.

[0039] 2: Melting and alloy optimization Material Selection: High-strength alloys are selected, specifically Al-Si-Mg alloys with high fluidity, such as A356 aluminum alloy. The impurity content is strictly controlled. The iron element content is controlled within 0.15% - 0.2%, and the copper element content is controlled within 0.05; Melting Process: Electromagnetic induction furnace is used for melting. The furnace temperature is raised to 720 - 750 °C to make the alloy heat evenly and reduce gas absorption and oxidation during the melting process. When the alloy is completely melted, 0.03% - 0.05% mass fraction of strontium (Sr) is added as a modifier for modification treatment. Stir evenly to refine the grains and improve the mechanical properties and fluidity of the alloy. Then, a refining agent is used for degassing and slag removal treatment. Argon is introduced, and the flow rate is controlled at 0.1 - 0.2 m³ / h, and the treatment time is 10 - 15 minutes to remove the gas and inclusions in the molten alloy; improve the purity of the molten alloy.

[0040] 3: Vacuum Die Casting Equipment Preparation: Advanced vacuum die-casting equipment is used. Before die casting, the mold cavity is evacuated to pump out the air in the cavity and make the internal air pressure in the cavity reach 5 - 8 kPa; effectively reduce the porosity and looseness defects inside the casting.

[0041] Die Casting Parameter Control: Precisely control various parameters during die casting. The injection speed is controlled in segments. The initial filling speed is 0.3 - 0.5 m / s to make the molten alloy fill the cavity smoothly and avoid turbulence and air entrainment; the filling speed in the later stage is increased to 3 - 5 m / s so that the molten alloy can fill every corner of the cavity, especially complex oil channels and thin-wall parts. The injection pressure is 30 - 50 MPa in the initial filling stage and increases to 80 - 120 MPa in the later filling stage. The holding pressure time is adjusted according to the average wall thickness of the pump body. When the wall thickness is less than 5 mm, the holding pressure time is 10 - 15 s; when the wall thickness is 5 - 10 mm, the holding pressure time is 15 - 25 s; when the wall thickness is greater than 10 mm, the holding pressure time is 25 - 40 s; ensure that the casting receives sufficient feeding during solidification and reduce shrinkage porosity defects.

[0042] 4: Rapid Cooling and Demolding Cooling System Optimization: An efficient cooling water channel system is designed inside the mold, and conformal cooling technology is adopted according to the shape and heat distribution of the pump body. The cooling medium is water, the inlet water temperature is controlled at 20 - 25 °C, and the water flow rate is 1 - 2 m / s, so that the casting can be cooled quickly and evenly during die casting. From the end of die casting to the casting cooling to the demolding temperature of 200 - 250 °C, it takes 3 - 5 minutes. Rapid cooling helps to refine the grains, improve the mechanical properties of the casting, and shorten the production cycle at the same time.

[0043] 5: Demolding treatment: After the casting cools down to 200 - 250 °C, an environmentally friendly and high-performance demolding agent is used to assist in demolding. The demolding agent is evenly sprayed on the mold surface at a pressure of 0.3 - 0.5 MPa to reduce the friction between the casting and the mold, ensuring that the casting can be smoothly demolded without affecting the surface quality of the casting. After demolding, the casting is preliminarily cleaned to remove the residual demolding agent and burrs on the surface; the cleaning time is about 1 - 2 minutes.

[0044] After the demolding treatment, it also includes: Stress relief treatment: The rough pump body blank after die casting is subjected to stress relief annealing treatment. The blank is placed in a heating furnace and heated to 280 - 320 °C at a heating rate of 50 - 100 °C per hour, held for 2 - 3 hours, and then cooled to room temperature with the furnace to eliminate the residual stress inside the casting; prevent deformation during subsequent processing and use.

[0045] Quality inspection: Advanced non-destructive testing technology is used. The detection voltage is 100 - 150 kV, and the detection time is 2 - 5 minutes according to the size of the pump body; ultrasonic flaw detection is carried out with a probe frequency of 2 - 5 MHz to comprehensively detect the rough pump body to check for internal defects (such as pores, shrinkage porosity, cracks, etc.); at the same time, a coordinate measuring machine is used to measure the key dimensions of the rough pump body; ensure that it meets the design requirements. For the rough blanks that fail the inspection, repair or scrapping is carried out according to the type and degree of the defects.

[0046] The preparation of the rough blank for the pump cover 2 during processing: The pump cover rough blank is made by casting or forging, specifically including: Material preparation: Metal powders with a particle size of 50 - 150 microns are selected (such as 316L stainless steel powder suitable for corrosion-resistant scenarios, or 6061 aluminum alloy powder for pursuing lightweight), specifically depending on the usage scenario and performance requirements of the pump cover; a high molecular resin binder is prepared according to the mass ratio of metal powder to binder of 10:1; at the same time, a water-soluble gypsum material for mold manufacturing is prepared; this material needs to have good formability and water solubility. Mold design and manufacturing: A mold model is constructed according to the design drawing of the pump cover (using professional 3D modeling software, such as SolidWorks), and the designed model is imported into an FDM (Fused Deposition Modeling) 3D printer. During the printing process, the printing temperature is set at 180 - 220 °C, the printing speed is 30 - 60 mm / s, and a water-soluble gypsum material is used to print the mold. After printing, the mold is processed by a grinding machine to make the surface roughness of the mold reach Ra0.8 - Ra1.6 μm, and the dimensional accuracy is controlled within the range of ±0.1 mm; Mixing and filling: Put the metal powder and binder into the mixing equipment and mix them at a stirring speed of 300-500 rpm for 15-20 minutes to ensure uniform mixing. Slowly fill the mixed material into the 3D printed mold, turn on the vibration auxiliary equipment during filling, and set the vibration frequency to 50-80Hz to ensure that the material is tightly filled; Curing and molding: Place the mold filled with materials in a hot air circulation curing furnace, raise the temperature to 150-180℃ at a heating rate of 5-10℃ / min, and keep it at this temperature for 30-45 minutes. During the curing process, the binder works to bond the metal powder and promote the initial formation of the pump cover blank. After curing, take out the mold from the curing furnace and cool it naturally to room temperature. Demolding and cleaning: After the mold cools to room temperature, immerse it in warm water at 40-50°C. Due to the characteristics of water-soluble gypsum materials, the mold will gradually dissolve within 20-30 minutes to complete demoulding. After demoulding, use a high-pressure water gun to wash the pump cover blank at a water pressure of 3-5MPa to remove the residual mold materials and impurities on the surface; Degreasing treatment: put the cleaned pump cover blank into a degreasing device with a temperature control device, add acetone as an organic solvent, set the degreasing temperature to 50-60℃, and the degreasing time to 60-90 minutes to ensure that the residual adhesive on the surface and inside of the blank is removed. During the degreasing process, good ventilation must be maintained to avoid the volatilization and accumulation of organic solvents; Sintering densification: Put the degreased pump cover blank into a high-temperature sintering furnace, introduce 99.99% pure nitrogen as a protective atmosphere, raise the temperature to 1200-1300℃ (for stainless steel powder) at a heating rate of 10-15℃ / min, and sinter at this temperature for 60-90 minutes. By precisely controlling the sintering temperature and time, atomic diffusion and fusion between metal powders are promoted, the density and strength of the blank are improved, and the final performance standard is achieved.

[0047] Preferably, the processing steps for the inner rotor 7 are as follows: After the raw materials are cut into billets, they are placed in a vacuum heating furnace and kept at 600-700°C for 1-2 hours for stress relief annealing to eliminate residual stress during processing; Special-shaped hole processing: Laser electrolysis composite processing technology is used. First, a high-energy pulse laser is used to process a pre-hole in the center area of ​​the blank. The laser pulse energy is controlled at 10-20 joules and the pulse frequency is 50-100 Hz. Then, the blank is placed in an electrolyte and the shaft hole is further accurately formed through electrolytic processing. The processing voltage is maintained at 10-15 volts and the current density is 10-15 amperes / square centimeter to ensure that the shaft hole accuracy reaches ±0.005mm and the surface roughness is Ra0.2-Ra0.4μm. Tooth profile machining: The electro-discharge milling process is used, and a special electrode is designed with high-purity graphite as the electrode material. The movement trajectory of the electrode is controlled by numerical control programming, and the tooth profile is simulated for milling. During the machining process, the discharge energy is controlled within 0.1 - 0.3 joules, and the pulse width is 10 - 20 microseconds. High-efficiency and high-precision tooth profile machining is achieved, and the tooth profile accuracy can reach the 5th level accuracy in GB / T10095.1 - 2008. Surface strengthening treatment: The ion implantation technology is adopted to implant nitrogen ions into the surface of the inner rotor. The implantation energy is 80 - 120 keV, and the implantation dose is 1×10¹ 7 - 3×10¹ 7 ions / cm²; A modified layer with high hardness and good wear resistance is formed on the surface. The surface hardness is increased by 2 - 3 times, significantly enhancing its service life.

[0048] In the present invention, preferably, the processing steps for the outer rotor 8 further include: Raw material forming: High-strength aluminum alloy plates are selected, and the hot pressing forming process is used. The plates are heated to 450 - 500 °C, placed in a mold, and held under pressure of 50 - 80 MPa for 5 - 10 minutes, and then cooled to room temperature to form the basic shape of the outer rotor 8; This step can effectively improve the internal structure of the material and enhance the comprehensive performance. Precision machining of the inner ring: The ultrasonic vibration-assisted grinding process is adopted. An ultrasonic vibration device is installed on ordinary grinding equipment. The vibration frequency is 20 - 30 kHz, and the amplitude is 10 - 20 μm. The inner ring is machined by a grinding wheel (cubic boron nitride grinding wheel is selected). The grinding parameters are grinding speed 30 - 40 m / s, feed rate 0.01 - 0.03 mm / r. The size accuracy of the inner ring is ±0.01 mm, and the surface roughness is Ra0.4 - Ra0.8 μm; The fitting accuracy between the inner ring and other components is improved. Surface treatment: The micro-arc oxidation technology is adopted to generate a ceramic oxide film on the surface of the aluminum alloy outer rotor. The electrolyte, treatment voltage is 300 - 400 V, and the treatment time is 15 - 25 minutes. The thickness of the generated oxide film is 10 - 20 μm, and the hardness is HV500 - HV800. The corrosion resistance and insulation performance of the surface are greatly improved.

[0049] Furthermore, the processing steps for the main shaft 6 further include: Blanking and rough machining: Raw materials are selected, cut into blanks of the required length, and rough turned on a lathe to machine the basic shape of the main shaft; including the outer circle, shaft shoulder, etc.

[0050] Milling a keyway on a milling machine for connection with the inner rotor 8 and the pulley 20; Drilling a center hole; Providing a positioning reference for subsequent machining and assembly.

[0051] Heat treatment and finishing: Perform heat treatment on the main shaft 6 to improve its strength and toughness. Then, through precision grinding, ensure the dimensional accuracy and surface roughness of the outer circle to meet the rotation requirements.

[0052] Flaw detection: Use non-destructive flaw detection, such as ultrasonic flaw detection or magnetic particle flaw detection, to check whether there are defects (such as cracks) inside the main shaft 6.

[0053] Furthermore, the processing of the pulley 2 is also included in the present invention. Blank manufacturing: Use casting or forging methods to make the pulley blank. Machining: Use a lathe to turn the outer circle and inner hole of the pulley 20 to ensure dimensional accuracy. Milling the pulley groove on a milling machine to make it fit the transmission belt. Drilling bolt holes and positioning holes for easy installation and fixation. Surface treatment: Treat the surface of the pulley 20, such as painting or electroplating, to improve its wear resistance and corrosion resistance.

[0054] Processing of the valve core and steel ball Valve core processing: Select a metal material and turn the basic shape of the valve core through machining. Then, perform grinding to ensure its dimensional accuracy and surface finish, enabling it to move flexibly in the oil passage. Steel ball processing: Use a sphere processing device for processing and perform surface polishing after processing. Spring processing: According to the design requirements, select spring wire and wind it into a spring of the required shape through a winding machine. Perform heat treatment on the spring to adjust its elastic coefficient. Then, perform shaping treatment to ensure that parameters such as the perpendicularity and free height of the spring meet the requirements.

[0055] Component assembly Assembly of the inner rotor 7 and outer rotor 8 with the main shaft: Install the inner rotor on the main shaft through key connection to ensure a firm connection. Then, install the outer rotor into the corresponding cavity of the pump body to make the inner and outer rotors mesh correctly. Assembly of the safety valve component: In the safety valve oil passage of the pump body, first place the steel ball, then install the safety valve spring, and finally seal the oil passage port with a bowl-shaped plug to install the safety valve component in place.

[0056] Assembly of the valve core and spring: In another oil passage of the pump body, install the spring, and then install the valve core at the front end of the spring to ensure that the valve core can move normally under the action of the spring force in the oil passage.

[0057] Assembly of the pump body and pump cover: Apply sealant on the mounting surface of the pump body, position the pump cover through the positioning pin sleeve, and then evenly tighten it with screws to ensure the sealing performance and assembly accuracy.

[0058] Pulley assembly: Install the pulley at one end of the main shaft through key connection and install the pulley flange to prevent axial movement of the pulley.

[0059] Overall Machine Inspection and Debugging Sealing Detection: Conduct a sealing test on the assembled oil pump. Inject a liquid with a certain pressure (such as engine oil) into the pump and check whether there is any leakage at each sealing part.

[0060] Performance Test: Install the oil pump on a test bench, simulate the actual working conditions, and test performance indicators such as the oil pumping pressure and flow rate at different speeds to ensure compliance with technical requirements (such as the pressure and flow rate standards at the specified speed).

[0061] Debugging and Optimization: According to the test results, debug the oil pump, such as adjusting the opening pressure of the safety valve and checking the operation of the rotor; adjust or replace the components that do not meet the requirements until the performance of the oil pump reaches the standard.

[0062] Cleaning and Packaging: Clean the qualified oil pump after inspection to remove internal impurities; then perform rust prevention treatment and finally package it for storage.

[0063] The above has described in detail the preferred specific embodiments of the present invention. It should be understood that those of ordinary skill in the art can make many modifications and variations based on the concept of the present invention without creative labor. Therefore, all technical solutions that can be obtained by those skilled in the art in the technical field of this technology through logical analysis, reasoning, or limited experiments based on the concept of the present invention on the basis of the prior art shall fall within the protection scope determined by the claims.

Claims

1. A large displacement oil pump, characterized by: comprising a pump body (1); A pump cover (2) is disposed on the pump body (1) and is used to seal the pump body (1); A main shaft (6) is inserted into the pump body (1) and is used to connect to an external power source and drive the inner rotor (7) to rotate; An inner rotor (7) is arranged in the pump body (1) and sleeved on the main shaft (6); An outer rotor (8) is arranged in the pump body (1) and sleeved on the inner rotor (7), and cooperates with the inner rotor (7) to suck in and squeeze out the engine oil; A limit spring (13) slidably disposed in the pump body (1); A valve core (14) is located in the pump body (1) and is used in conjunction with a limit spring (13); A steel ball (11) is arranged in the pump body (1) and is located between the bowl-shaped plug (10) and the safety valve spring (12).

2. The large displacement oil pump according to claim 1, characterized in that: Also includes A pulley (20) is arranged outside the pump body (1) and sleeved on the main shaft (6), and is used to drive the main shaft (6) to rotate; The pulley rib (21) is arranged between the pump cover (2) and the pulley (20) and is used to axially limit the pulley (20).

3. The manufacturing process of the large displacement oil pump according to claim 2, characterized in that: include Pump body (1) processing Blank production: The pump body blank is manufactured by die-casting process; Rough machining: Deburring the pump body (1) blank, then milling the mounting surface; drilling the oil channel hole; Finishing: performing fine milling and grinding on the inner and outer contours of the pump body (1), and cleaning the processed pump body (1); Pump cover (2) processing Blank preparation: The pump cover blank is made by casting or forging; Processing and forming: firstly, the plane of the pump cover (2) is milled; then holes are drilled, and the sealing surface that matches the pump body (1) is ground or polished; Quality inspection: Check the dimensional accuracy and surface quality of the pump cover.

4. The manufacturing process of the large displacement oil pump according to claim 3, characterized in that: The method of manufacturing the pump body (1) blank by die casting specifically comprises: 1: Mold design and pretreatment Mold design: perform three-dimensional modeling of the mold and eliminate defects by simulating the die-casting process; Mould pretreatment: Select steel material, first quench it, heat it to 1020-1050℃, keep it warm for 2-3 hours, then temper it at 550-580℃, temper it 3 times, keep it warm for 2-3 hours each time, and nitride the mould surface before use, the nitriding temperature is 500-550℃, and the nitriding time is 20 - 30 hours; 2: Melting and alloy optimization Material selection: Use high-strength alloy, the iron content is controlled within 0.15%-0.2%, and the copper content is controlled within 0.05; Melting process: Use electromagnetic induction furnace for melting, raise the furnace temperature to 720-750℃, when the alloy is completely melted, add 0.03% -0.05% mass fraction of strontium as a modifier for modification, stir evenly, refine the grains, then use refining agent for degassing and deslagging, introduce argon, the flow rate is controlled at 0.1-0.2m³ / h, the treatment time is 10-15 minutes, remove the gas and inclusions in the alloy liquid; 3: Vacuum die casting Equipment preparation: Before die-casting, the mold cavity is vacuumed to extract the air in the cavity so that the internal pressure of the cavity reaches 5-8kPa; Die casting parameter control: The injection speed is controlled in sections. The initial speed of filling is 0.3-0.5m / s, so that the alloy liquid can fill the cavity smoothly and avoid turbulence and air entrainment. The speed is increased to 3-5m / s in the later stage of filling, so that the alloy liquid can fill every corner of the cavity. The injection pressure is 30-50MPa in the initial stage of filling, and increases to 80-120MPa in the later stage of filling. The holding time is adjusted according to the average wall thickness of the pump body. When the wall thickness is less than 5mm, the holding time is 10-15s; when the wall thickness is 5-10mm, the holding time is 15-25s; when the wall thickness is greater than 10mm, the holding time is 25-40s. 4: Rapid cooling and demoulding Cooling system optimization: A cooling water system is used inside the mold, the water inlet temperature is controlled at 20-25°C, and the water flow rate is 1-2m / s; 5: Demolding: After the casting is cooled to 200-250℃, a release agent is used to assist demolding. The release agent is evenly sprayed on the mold surface at a pressure of 0.3-0.5MPa to reduce the friction between the casting and the mold. After demolding, the casting is preliminarily cleaned to remove the release agent residue and burrs on the surface.

5. The manufacturing process of the large displacement oil pump according to claim 4, characterized in that: The demoulding process also includes: Stress relief treatment: The pump body blank after die casting is subjected to stress relief annealing treatment. The blank is placed in a heating furnace and heated to 280-320℃ at a heating rate of 50-100℃ per hour. It is kept warm for 2-3 hours and then cooled to room temperature with the furnace to eliminate the residual stress inside the casting. Quality inspection: non-destructive testing technology is used, with a test voltage of 100-150kV and a test time of 2-5 minutes; ultrasonic flaw detection with a probe frequency of 2-5MHz is used to conduct a comprehensive inspection of the pump body blank to check whether there are any internal defects; at the same time, a three-coordinate measuring instrument is used to measure the size of the pump body blank; for blanks that fail the inspection, they are repaired or scrapped.

6. The manufacturing process of the large displacement oil pump according to claim 5, characterized in that: The blank preparation in the processing of the pump cover (2): the pump cover blank is made by casting or forging, specifically comprising: Material preparation: Select metal powder with a particle size of 50-150 microns and prepare a polymer resin binder at a mass ratio of 10:1 between metal powder and binder; at the same time, prepare water-soluble gypsum material for mold manufacturing; Mold design and production: Build the mold model according to the design drawings of the pump cover, import the designed model into the FDM printer, and print the mold using water-soluble gypsum material. After printing, process the mold with a grinder to make the mold surface roughness reach Ra0.8-Ra1.6μm, and the dimensional accuracy is controlled within the range of ±0.1mm; Mixing and filling: Put the metal powder and binder into the mixing equipment, mix them at a stirring speed of 300-500 rpm for 15-20 minutes, and fill the mixed material into the printed mold. When filling, turn on the vibration auxiliary equipment and set the vibration frequency to 50-80Hz to ensure that the material is tightly filled; Curing and molding: Place the mold filled with materials in a hot air circulation curing furnace, raise the temperature to 150-180℃ at a heating rate of 5-10℃ / min, and keep it at this temperature for 30-45 minutes. During the curing process, the binder works to bond the metal powder and promote the initial formation of the pump cover blank. After curing, take out the mold from the curing furnace and cool it naturally to room temperature. Demolding and cleaning: After the mold cools to room temperature, immerse it in warm water at 40-50°C. Due to the characteristics of water-soluble gypsum materials, the mold will gradually dissolve within 20-30 minutes to complete demoulding. After demoulding, use a high-pressure water gun to wash the pump cover blank at a water pressure of 3-5MPa to remove the residual mold materials and impurities on the surface; Degreasing treatment: put the cleaned pump cover blank into the degreasing equipment with temperature control device, add acetone as organic solvent, set the degreasing temperature to 50-60℃, and the degreasing time to 60-90 minutes. During the degreasing process, good ventilation should be maintained; Sintering densification: Put the degreased pump cover blank into a high-temperature sintering furnace, introduce 99.99% pure nitrogen as a protective atmosphere, increase the temperature to 1200-1300℃ at a heating rate of 10-15℃ / min, and sinter at this temperature for 60-90 minutes.

7. The manufacturing process of the large displacement oil pump according to claim 6, characterized in that: The method further includes the steps of processing the inner rotor (7): After the raw materials are cut into billets, they are placed in a vacuum heating furnace and kept at 600-700°C for 1-2 hours for stress relief annealing to eliminate residual stress during processing; Special-shaped hole processing: Laser electrolysis composite processing technology is used. First, a high-energy pulse laser is used to process a pre-hole in the center area of ​​the blank. The laser pulse energy is controlled at 10-20 joules and the pulse frequency is 50-100 Hz. Then, the blank is placed in an electrolyte and the shaft hole is further accurately formed through electrolytic processing. The processing voltage is maintained at 10-15 volts and the current density is 10-15 amperes / square centimeter to ensure that the shaft hole accuracy reaches ±0.005mm and the surface roughness is Ra0.2-Ra0.4μm. Tooth processing: Using the EDM milling process, the electrode motion trajectory is controlled by CNC programming to simulate the tooth profile for milling. During the processing, the discharge energy is controlled at 0.1-0.3 joules and the pulse width is 10-20 microseconds. Surface strengthening treatment: Ion implantation technology is used to implant nitrogen ions into the inner rotor surface, with an injection energy of 80-120 keV and an injection dose of 1×10¹ 7 -3×10¹ 7 ions / cm2; forming a modified layer on the surface.

8. The manufacturing process of the large displacement oil pump according to claim 7, characterized in that: The processing steps of the outer rotor (8) are as follows: Raw material molding: using a hot pressing molding process, the plate is heated to 450-500°C, placed in a mold, maintained at a pressure of 50-80 MPa for 5-10 minutes, cooled to room temperature, and molded into the basic shape of the outer rotor (8); Inner ring precision machining: installing an ultrasonic vibration device on the grinding equipment, with a vibration frequency of 20-30 kHz and an amplitude of 10-20 μm, grinding with a grinding wheel, grinding parameters of grinding speed 30-40 m / s, feed rate 0.01-0.03 mm / r, machining the inner ring, the inner ring dimensional accuracy ±0.01 mm, surface roughness Ra0.4-Ra0.8 μm; Surface treatment: A ceramic oxide film is generated on the surface of the aluminum alloy outer rotor, the electrolyte, the treatment voltage is 300-400 volts, the treatment time is 15-25 minutes, the thickness of the generated oxide film is 10-20μm, and the hardness is HV500-HV800.

9. The manufacturing process of a large displacement oil pump as claimed in claim 8, characterized in that: The processing steps for the spindle (6) are also included: Cutting and rough processing: Select the raw materials, cut them into blanks of required length, and use the lathe to perform rough turning to produce the basic shape of the spindle; Milling a keyway on a milling machine for connection with the inner rotor (8) and the pulley (20); drilling a center hole; Heat treatment and finishing: heat treatment of the spindle (6); Flaw detection: Use non-destructive testing to check whether there are any defects inside the spindle (6).

10. The manufacturing process of a large displacement oil pump according to claim 9, characterized in that: Also included is pulley (20) processing; Blank manufacturing: The pulley blank is made by casting or forging; Mechanical processing: turning the outer circle and inner hole of the pulley (20) on a lathe; milling the pulley groove on a milling machine; drilling bolt holes and positioning holes; Surface treatment: treating the surface of the pulley (20); Valve core processing: metal materials are selected, the basic shape of the valve core is machined by turning, and then ground to ensure its dimensional accuracy and surface finish, so that it can move flexibly in the oil channel; Steel ball processing: Use ball processing equipment for processing, and then perform surface polishing after processing; Spring processing: According to the design requirements, select spring steel wire and use the winding machine to wind the spring into the required shape; heat treat the spring to adjust its elastic coefficient; Then plastic surgery is performed.

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