A resin-sealed powder metallurgy stainless steel vacuum pump chamber and its preparation process

Abstract

This invention relates to the field of powder metallurgy technology and discloses a resin-sealed powder metallurgy stainless steel vacuum pump chamber and its manufacturing process. The pump chamber includes a pump wall, the inner wall of which is equipped with a stabilizing component for constant-pressure injection of new oil and simultaneous discharge of waste oil and wear particles. The inner wall of the pump wall is provided with a wear-resistant layer. This device, through an oil supply chamber, a silicon carbide ceramic infiltration layer, and an orifice plate with tapered holes, drives the circulation of cold lubricating oil by utilizing the pressure difference between the negative pressure chamber and the high-pressure chamber of the pump chamber itself. After two stages of pressure stabilization and flow restriction by the infiltration layer and the orifice plate, the cold lubricating oil uniformly penetrates into the inner wall of the wear-resistant layer in the form of a capillary liquid surface, achieving a constant-pressure and stable oil supply. This avoids interference with the vacuum level of the pump chamber caused by the oil supply action. Without affecting the vacuum generation efficiency, it provides full-coverage lubrication and cooling for the friction pair, reducing wear and heat generation from the source, while protecting the resin-sealed layer of the powder metallurgy matrix.

Description

Technical Field

[0001] This invention relates to the field of powder metallurgy technology, and in particular to a resin-sealed powder metallurgy stainless steel vacuum pump chamber and its preparation process. Background Technology

[0002] Electronic vacuum pumps are mainly used in the braking systems of automatic transmission vehicles, turbocharged engines, and electric vehicles to reduce the force required to operate the brake pedal. They consist of key components such as the pump chamber, pump chamber cover, pump body cover, pump core rotor, sweeping vanes, and shaft. With the country's vigorous promotion of new energy vehicle research and development, electric vehicle braking systems, lacking an engine, cannot obtain vacuum from it. However, electronic vacuum pumps can provide a certain degree of vacuum to the electric vehicle braking system, ensuring braking with a certain vacuum boost ratio. This effectively solves the problem of electric vehicle braking systems, making the role of electronic vacuum pumps in the future development of automobiles undeniable.

[0003] Traditional stainless steel parts are mostly produced by casting and forging. The former has defects such as difficult machining, poor dimensional accuracy, and easy formation of shrinkage cavities and sand holes, while the latter has poor plasticity, difficult deformation, low material utilization, and high cost, all of which have technical bottlenecks. However, the development of atomization powder production technology has promoted the application of powder metallurgy stainless steel, which can improve the production efficiency of pump chambers and reduce production costs.

[0004] However, the aforementioned vacuum pumps still have the following shortcomings in the inner wall of the pump chamber during operation: First, the continuous sliding friction between the sweeping blades and the inner wall of the pump chamber during operation easily generates wear particles. These particles not only form abrasive particles that exacerbate wear on the inner wall, but also scratch the resin sealing layer, leading to exposure of micropores in the matrix, a significant decrease in airtightness, and a safety hazard of vacuum failure. However, the existing cold lubricating oil solution cannot achieve constant pressure and stable flow control. High-pressure oil flow easily disrupts the vacuum environment of the pump chamber, and insufficient oil volume exacerbates dry friction and temperature rise. Aging waste oil and wear particles cannot be discharged synchronously and directionally, which easily causes oil circuit blockage and continuous degradation of the performance of cold lubricating oil, making it unsuitable for the long-term, high-reliability operation requirements of electronic vacuum pumps for new energy vehicles. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention proposes a resin-sealed powder metallurgy stainless steel vacuum pump chamber and its preparation process.

[0006] To achieve the above objectives, this application adopts the following technical solution: a resin-sealed powder metallurgy stainless steel vacuum pump chamber, including a pump wall, wherein the inner wall of the pump wall is provided with a stabilizing component for constant pressure injection of new oil into the pump and simultaneous discharge of waste oil and wear particles, and the inner wall of the pump wall is provided with a wear-resistant layer.

[0007] The stabilizing component includes multiple sets of slag discharge grooves opened on the inner wall of the wear-resistant layer. Multiple sets of oil supply chambers for introducing new oil from the outside to the inside are symmetrically opened on the inner wall of the wear-resistant layer. Multiple sets of oil discharge chambers for discharging waste oil and wear particles from the inside to the outside are also symmetrically opened on the inner wall of the wear-resistant layer. An orifice plate is embedded in the oil supply chamber. Multiple sets of conical holes are equally spaced on the surface of the orifice plate to reduce the flow rate of new oil and to form a relatively uniform capillary liquid surface. A seepage layer is embedded in the oil supply chamber and on one side of the orifice plate to reduce the flow rate of new oil and maintain the internal air pressure of the pump wall at a relatively constant level.

[0008] The internal shape of the pump wall is elliptical.

[0009] Preferably, the multiple sets of slag discharge troughs are symmetrical, and the slag discharge troughs are inclined as a whole.

[0010] Preferably, the inner wall of the slag discharge trough is a curved arc shape with one end wider than the other, wherein a group of oil discharge chambers, oil supply chambers and slag discharge troughs that are close to each other constitute a circulation group.

[0011] Preferably, the oil discharge chamber is connected to a treatment device for cooling and purifying waste oil via an external oil circuit, and the oil discharge chamber is connected to the narrower end of the slag discharge tank.

[0012] Preferably, the oil supply chamber is connected to the processing equipment via an external oil circuit.

[0013] Preferably, the inner wall of one end of the oil drain chamber and the oil supply chamber is elongated and inclined at a certain angle, and the other end of the oil drain chamber and the oil supply chamber are connected to a connecting pipe for external oil circuit.

[0014] Preferably, the main material of the infiltrated layer is silicon carbide ceramic, which has high strength and relatively stable chemical properties.

[0015] Preferably, the inner walls of both ends of the tapered hole are frustoconical, and the opening and axial length of the tapered hole at the end closest to the pump wall are both greater than those at the other end.

[0016] Preferably, a rotor is installed at the center of the pump wall, and multiple sets of sweeping blades are slidably inserted into the outer wall of the rotor, with each set of sweeping blades inclined at a certain angle, and one end of the sweeping blades slidingly contacting the inner wall of the wear-resistant layer.

[0017] The manufacturing process of the pump chamber of a resin-sealed powder metallurgy stainless steel vacuum pump includes the following steps:

[0018] S1. Raw material preparation and integrated pressing: Weigh 430L of water-atomized ferritic stainless steel powder, high-purity copper powder of the corresponding proportion, and an appropriate amount of molding agent according to the preset ratio, and put them into the mixing equipment for thorough mixing to obtain a uniformly dispersed mixed powder; fill the mixed powder into a precision mold that is compatible with the pump chamber foundation structure, press it under preset pressure, and slowly release the pressure after holding the pressure to demold, thereby obtaining a pump chamber green blank with an integrated elliptical inner cavity. The density and dimensional accuracy of the green blank meet the molding design requirements.

[0019] S2. Vacuum sintering and precision machining: The green billet in the pump chamber is neatly placed in the sintering support fixture and sent into the vacuum sintering furnace for segmented heating and sintering in a vacuum environment.

[0020] First, the temperature is raised to the low temperature range at a preset rate and held to completely remove the forming agent; then the temperature is raised to the sintering temperature range at a preset rate and held to complete the metallurgical sintering. After cooling in the furnace, the product is taken out of the furnace to obtain the pump chamber sintered matrix. The porosity and hardness of the matrix meet the design requirements.

[0021] After the sintered substrate is corrected for sintering deformation by shaping mold, the basic machining of mounting holes, positioning holes and inner cavity mating surfaces is completed first. Then, the slag discharge trough, oil supply cavity and oil discharge cavity are precision shaped. After precision finishing, the dimensional accuracy, geometric tolerances and surface finish of each structure meet the design requirements of the drawings.

[0022] S3. Local hardening treatment and stable component assembly: A fiber laser is used to perform local laser surface alloying treatment on the wear-resistant layer area of ​​the pump chamber wall. The entire process is protected by inert gas to avoid oxidation, resulting in a wear-resistant layer that meets the design requirements for hardness and hardened layer depth. After hardening, a low-temperature tempering treatment is performed to completely release the internal stress of processing.

[0023] First, a silicon carbide ceramic diffusion layer and a perforated plate with honeycomb array conical holes are sequentially press-fitted into the oil supply chamber. After pressing, a sealing and fixing treatment is performed to ensure that the components are not loose and the oil circuit is leak-free. Then, the external oil circuit connection pipe is assembled and the corresponding interface of the connection pipe is fixedly connected to the oil supply chamber and the oil discharge chamber. The connection is sealed and reinforced to prevent leakage and air leakage in the external oil circuit.

[0024] S4. Resin sealing and full-item inspection of finished products: The assembled pump chamber is subjected to ultrasonic cleaning, deionized water rinsing, and vacuum drying in sequence to thoroughly remove cutting impurities, welding fumes and moisture from the surface and pores; then the pump chamber is placed in an impregnation tank, vacuumed and pressurized, and preheated mineral oil-resistant modified epoxy resin is injected. After impregnation under negative pressure, compressed air is introduced to increase and maintain pressure to complete full-pore vacuum and pressurized sealing.

[0025] The pump chamber is removed to remove excess resin from its surface. After being cured by step heating, it undergoes dehydration and rust prevention treatment. Finally, it is subjected to full-item testing for dimensional accuracy, hardness, airtightness, oil circuit continuity, and sealing quality. Once the tests are passed, the finished pump chamber is obtained.

[0026] The technical effects and advantages of this invention are as follows:

[0027] In this invention, the device uses an oil supply chamber, a silicon carbide ceramic diffusion layer, and an orifice plate with tapered holes to drive the circulation of cold lubricating oil by means of the pressure difference between the negative pressure chamber and the high pressure chamber of the pump chamber itself. After two stages of pressure stabilization and flow restriction by the diffusion layer and the orifice plate, the cold lubricating oil is uniformly penetrated into the inner wall of the wear-resistant layer in the form of capillary liquid surface, realizing constant pressure and stable oil supply of cold lubricating oil. This avoids the interference of oil supply action on the vacuum degree of the pump chamber. Without affecting the vacuum generation efficiency, it provides full-coverage lubrication and cooling for the friction pair, reducing wear and heat generation from the source, while protecting the resin sealing layer of the powder metallurgy matrix.

[0028] In this invention, the device utilizes a rotating sweeping blade, an inclined curved slag discharge trough (wide at one end and narrow at the other), an oil discharge chamber, external oil treatment equipment, and an oil supply chamber. The rotating sweeping blades directionally push wear particles and waste cold lubricating oil from the wear-resistant layer surface into the slag discharge trough. The pressure difference in the high-pressure chamber of the pump chamber then sends the waste oil and particles into the oil discharge chamber. After purification and cooling by external equipment, the waste oil and particles are reintroduced into the oil supply chamber for circulation. This achieves real-time directional discharge of wear particles and closed-loop recycling of cold lubricating oil, preventing particle accumulation from forming abrasive particles that exacerbate wear and scratch the resin sealing layer. This significantly improves the operational stability, airtightness, and service life of the pump chamber. Attached Figure Description

[0029] The disclosure of this invention is illustrated with reference to the accompanying drawings. It should be understood that the drawings are for illustrative purposes only and are not intended to limit the scope of protection of this invention. In the drawings, the same reference numerals are used to refer to the same parts:

[0030] Figure 1 This is a schematic diagram of the main structure of the present invention;

[0031] Figure 2 This is a schematic diagram of the main internal structure of the present invention;

[0032] Figure 3 This is a cross-sectional schematic diagram of a portion of the pump wall structure of the present invention;

[0033] Figure 4 This is a schematic diagram of the main structure of the slag discharge trough of the present invention;

[0034] Figure 5 This is a schematic diagram of the perforated plate structure of the present invention;

[0035] Figure 6 This is a schematic diagram of the oil supply chamber structure of the present invention;

[0036] Figure 7 This is a cross-sectional schematic diagram of the oil supply chamber structure of the present invention;

[0037] Figure 8 This is a cross-sectional schematic diagram of the perforated plate structure of the present invention;

[0038] Figure 9 This is a top view of the structure of the present invention.

[0039] Legend: 1. Pump wall; 101. Wear-resistant layer; 11. Slag discharge trough; 12. Oil discharge chamber; 121. Oil supply chamber; 13. Seepage layer; 14. Orifice plate; 141. Conical hole; 2. Rotor; 3. Sweeping blade. Detailed Implementation

[0040] It is readily understood that, based on the technical solution of this invention, those skilled in the art can propose various interchangeable structural methods and implementations without altering the essential spirit of the invention. Therefore, the following detailed embodiments and accompanying drawings are merely illustrative examples of the technical solution of this invention and should not be considered as the entirety of the invention or as limitations or restrictions on the technical solution of this invention.

[0041] Reference Figure 1-9 As shown, the present invention provides a technical solution: a resin-sealed powder metallurgy stainless steel vacuum pump chamber, including a pump wall 1. The pump wall 1 is a 430L ferritic stainless steel powder metallurgy integral sintered structure with 5wt% (mass percentage) of high-purity copper powder added. After sintering, the matrix porosity is about 8%-12%. The whole is treated with mineral oil-resistant modified epoxy resin through vacuum and pressure impregnation to complete full-pore sealing treatment. The inner wall of the pump wall 1 is provided with a stabilizing component for constant pressure feeding of new oil into its interior and simultaneous discharge of waste oil and wear particles. The inner wall of the pump wall 1 is provided with a wear-resistant layer 101. The wear-resistant layer 101 is a locally hardened layer formed on the inner wall of the pump wall 1 through laser surface alloying process. The hardness is stable at HRC55-60. It is metallurgically bonded to the pump wall 1 matrix and has no risk of cracking or falling off.

[0042] The "oil" specifically refers to lubricating oil that has both cooling and lubricating properties.

[0043] The stabilizing component includes multiple sets of slag discharge grooves 11 formed on the inner wall of the wear-resistant layer 101. Multiple sets of oil supply chambers 121 for introducing new oil from the outside to the inside are symmetrically formed on the inner wall of the wear-resistant layer 101. Multiple sets of oil discharge chambers 12 for discharging waste oil and wear particles from the inside to the outside are also symmetrically formed on the inner wall of the wear-resistant layer 101. The positions of the oil supply chambers 121 correspond perfectly to the negative pressure suction chamber of the elliptical pump chamber during operation, and the positions of the oil discharge chambers 12 correspond perfectly to the high pressure exhaust chamber of the elliptical pump chamber during operation. The high and low pressure difference of the pump chamber itself enables the smooth intake and active discharge of cold lubricating oil, completely avoiding the interference of the oil supply action on the vacuum of the pump chamber. An orifice plate 14 is embedded in the oil supply chamber 121. Multiple sets of conical holes 141 are equally spaced on the surface of the orifice plate 14 to reduce the flow rate of new oil and to form a relatively uniform capillary liquid surface. A seepage layer 13 is embedded in the oil supply chamber 121 and on one side of the orifice plate 14 to reduce the flow rate of new oil and keep the internal air pressure of the pump wall 1 relatively constant.

[0044] The internal shape of the pump wall 1 is elliptical, which is compatible with the working principle of variable displacement vacuum pump of vane vacuum pump. It can form a periodically changing high pressure chamber and low pressure chamber during the rotation of rotor 2.

[0045] Reference Figure 4-9 As shown in this embodiment: multiple sets of slag discharge tanks 11 are symmetrical, and the slag discharge tanks 11 are inclined as a whole. Their inclination direction is completely matched with the rotation direction of the sweeping blades 3. With the help of the thrust and centrifugal force of the rotating sweeping blades 3, the wear particles on the surface of the wear-resistant layer 101 and the waste cold lubricating oil can be directionally introduced into the tank.

[0046] Furthermore, the inner wall of the slag discharge trough 11 is a curved arc shape with one end wider and the other end narrower. A group of adjacent oil discharge chambers 12, oil supply chambers 121, and slag discharge troughs 11 form a circulation group. The wider end of the slag discharge trough 11 faces the direction of rotation of the sweeping blade 3, which is used to efficiently collect waste cold lubricating oil and wear particles from the surface of the wear-resistant layer 101. The narrower end is directly connected to the oil discharge chamber 12 in the same circulation group. The oil flow rate is increased through the narrowing structure, which avoids the accumulation of particles and the blockage of the pipeline. Each circulation group corresponds to an independent high and low pressure chamber, forming an independent closed loop of oil supply, lubrication, slag collection, and oil discharge. The symmetrical arrangement of multiple circulation groups can improve the lubrication effect of the pump chamber around the whole circle and eliminate dead corners in slag discharge.

[0047] The oil discharge chamber 12 is connected to a treatment device for cooling and purifying waste oil via an external oil circuit. The oil discharge chamber 12 is connected to the narrower end of the slag discharge tank 11, which can transport the collected waste cold lubricating oil and wear particles to the external treatment device. After cooling, filtration, purification and impurity removal, the oil is sent back to the oil supply chamber 121 for recycling.

[0048] Furthermore, the oil supply chamber 121 is connected to the processing equipment through an external oil circuit, and is used to receive clean cold lubricating oil after it has been purified and cooled by the external processing equipment, so as to provide a continuous and stable lubrication and cooling medium for the pump chamber.

[0049] The inner wall of one end of the oil drain chamber 12 and the oil supply chamber 121 is elongated and inclined at a certain angle. The inclination angle matches the distribution angle of the high and low pressure chambers of the pump chamber, which can ensure that the cold lubricating oil flows smoothly and the pressure is stable throughout the process, without turbulence or pressure fluctuation. The other end of the oil drain chamber 12 and the oil supply chamber 121 are connected to the connecting pipe for external oil circuit. The connecting pipe and the pump wall 1 are assembled and connected. The connection is sealed and reinforced to prevent leakage and air leakage in the external oil circuit.

[0050] The main material of the seepage layer 13 is silicon carbide ceramic, which has high strength and relatively stable chemical properties. It can achieve the first flow restriction, uniform distribution and pressure stabilization of the incoming cold lubricating oil, which significantly reduces the flow rate of high-speed oil and stabilizes the pressure. This fundamentally prevents high-pressure cold lubricating oil from directly rushing into the pump chamber and destroying the internal vacuum environment. At the same time, the silicon carbide ceramic material has excellent high temperature resistance and oil corrosion resistance, and can maintain stable performance in the long-term high temperature working environment of the pump chamber without the risk of aging or cracking.

[0051] Both ends of the conical hole 141 have frustoconical inner walls, and the opening and axial length of the end of the conical hole 141 closest to the pump wall 1 are larger than those of the other end. Multiple sets of conical holes 141 are arranged in a honeycomb-like array with equal spacing on the surface of the orifice plate 14, which can achieve a second uniform distribution of the cold lubricating oil after it has been stabilized by the permeation layer 13. By using the size difference between the openings at both ends to form a Venturi effect, the cold lubricating oil slowly and evenly penetrates into the inner wall of the wear-resistant layer 101 in the form of a capillary liquid surface, which ensures that the lubrication surface of the pump chamber is fully covered, and prevents the pressure fluctuation and vacuum failure of the pump chamber due to excessive instantaneous oil volume.

[0052] Reference Figure 1-9 As shown in this embodiment: a rotor 2 is installed at the center of the pump wall 1. Multiple sets of sweeping blades 3 are slidably inserted into the outer wall of the rotor 2, and each set of sweeping blades 3 is inclined at a certain angle. The inclination angle of the sweeping blades 3 matches the rotation direction of the rotor 2, which can improve the adhesion stability between the sweeping blades 3 and the wear-resistant layer 101 and reduce vibration and wear during rotation. One end of the sweeping blades 3 slides in contact with the inner wall of the wear-resistant layer 101. When the rotor 2 rotates, the sweeping blades 3 extend outward along the radial direction of the rotor 2 under the action of centrifugal force. Its end always keeps in close contact with the wear-resistant layer 101, forming multiple sets of sealed working chambers with periodically changing volume in the elliptical pump chamber to complete the vacuum generation process. At the same time, every time the sweeping blades 3 rotate once, they can push the wear particles on the surface of the wear-resistant layer 101 and the waste cold lubricating oil into the slag discharge tank 11 of the corresponding circulation group to achieve real-time slag removal, avoid the accumulation of particles on the sealed working surface to form abrasive particles that aggravate wear, and also prevent particles from scratching the resin sealing layer, causing the micropores of the substrate to be exposed and leaking.

[0053] The manufacturing process of the pump chamber of a resin-sealed powder metallurgy stainless steel vacuum pump includes the following steps:

[0054] S1. Raw material preparation and integrated pressing: Weigh 430L of water-atomized ferritic stainless steel powder, high-purity copper powder of the corresponding proportion, and an appropriate amount of molding agent according to the preset ratio, and put them into the mixing equipment for thorough mixing to obtain a uniformly dispersed mixed powder; fill the mixed powder into a precision mold that is compatible with the pump chamber foundation structure, press it under preset pressure, and slowly release the pressure after holding the pressure to demold, thereby obtaining a pump chamber green blank with an integrated elliptical inner cavity. The density and dimensional accuracy of the green blank meet the molding design requirements.

[0055] S2. Vacuum sintering and precision machining: The green billet in the pump chamber is neatly placed in the sintering support fixture and sent into the vacuum sintering furnace for segmented heating and sintering in a vacuum environment.

[0056] First, the temperature is raised to the low temperature range at a preset rate and held to completely remove the forming agent; then the temperature is raised to the sintering temperature range at a preset rate and held to complete the metallurgical sintering. After cooling in the furnace, the product is taken out of the furnace to obtain the pump chamber sintered matrix. The porosity and hardness of the matrix meet the design requirements.

[0057] After the sintered substrate is corrected for sintering deformation by shaping mold, the basic machining of mounting holes, positioning holes and inner cavity mating surfaces is completed first. Then, the slag discharge groove 11, oil supply chamber 121 and oil discharge chamber 12 are precision machined and shaped. After precision finishing, the dimensional accuracy, geometric tolerances and surface finish of each structure meet the design requirements of the drawings.

[0058] S3. Local hardening treatment and stable component assembly: A fiber laser is used to perform local laser surface alloying treatment on the wear-resistant layer 101 area of ​​the pump chamber wall. The entire process is protected by inert gas to avoid oxidation, resulting in a wear-resistant layer 101 that meets the design requirements for hardness and hardened layer depth. After hardening, a low-temperature tempering treatment is performed to completely release the internal stress of processing.

[0059] First, a silicon carbide ceramic diffusion layer 13 and a perforated plate 14 with honeycomb array conical holes 141 are sequentially press-fitted into the oil supply chamber 121. After pressing, a sealing and fixing treatment is performed to ensure that the components are not loose and the oil circuit is not leaking. Then, the external oil circuit connection pipe is assembled and the connection pipe is fixedly connected to the corresponding interface of the oil supply chamber 121 and the oil discharge chamber 12. The connection is sealed and reinforced to prevent leakage and air leakage in the external oil circuit.

[0060] S4. Resin sealing and full-item inspection of finished products: The assembled pump chamber is subjected to ultrasonic cleaning, deionized water rinsing, and vacuum drying in sequence to thoroughly remove cutting impurities, welding fumes and moisture from the surface and pores; then the pump chamber is placed in an impregnation tank, vacuumed and pressurized, and preheated mineral oil-resistant modified epoxy resin is injected. After impregnation under negative pressure, compressed air is introduced to increase and maintain pressure to complete full-pore vacuum and pressurized sealing.

[0061] The pump chamber is removed to remove excess resin from its surface. After being cured by step heating, it undergoes dehydration and rust prevention treatment. Finally, it is subjected to full-item testing for dimensional accuracy, hardness, airtightness, oil circuit continuity, and sealing quality. Once the tests are passed, the finished pump chamber is obtained.

[0062] Working principle: First, when the pump chamber is working, the rotor 2 drives multiple sets of sweeping blades 3 to rotate along the inner wall of the elliptical pump wall 1. Under the action of centrifugal force, the sweeping blades 3 extend outward, and their ends always maintain sliding contact with the wear-resistant layer 101, thereby forming a sealed working chamber with periodically changing volume inside the elliptical pump chamber, realizing the vacuum generation process of air intake, compression, and exhaust. This is existing technology, so it will not be described in detail. During this process, tiny wear particles will be continuously generated between the sweeping blades 3 and the wear-resistant layer 101, and between the ends of the sweeping blades 3 and the two ends of the pump wall 1. At the same time, the cold lubricating oil will gradually age after long-term high-temperature operation, and needs to be drained and replenished with new oil in time to maintain the stability of vacuum, temperature, sealing and wear resistance.

[0063] Secondly, the stabilizing component begins to perform constant pressure oil supply and synchronous oil discharge functions. The external processing equipment sends the cooled and purified new oil into the oil supply chamber 121. The new oil first enters the oil supply chamber 121 and flows through the permeation layer 13 and the orifice plate 14 in sequence.

[0064] Among them, the permeation layer 13 is made of high-strength, chemically stable silicon carbide ceramic material, which can limit and distribute the incoming new oil for the first time, reduce the oil flow rate and stabilize the pressure, and prevent high-pressure oil from directly rushing into the pump chamber and destroying the vacuum.

[0065] The multiple sets of conical holes 141 arrayed on the surface of the orifice plate 14 allow for a second uniform distribution of the new oil. The opening and shaft length of the conical hole 141 near the pump wall 1 are both greater than those at the other end, allowing the oil flow to slowly and evenly penetrate into the inner wall of the wear-resistant layer 101 in the form of a capillary liquid surface. This ensures full coverage of the lubrication surface and prevents pressure fluctuations in the cavity due to excessive oil volume.

[0066] Furthermore, the uniformly seeping cold lubricating oil forms a continuous and stable oil film between the sweeper blade 3 and the wear-resistant layer 101. On the one hand, it reduces the frictional resistance and heat generation during the rotation of the sweeper blade 3. On the other hand, it protects the surface of the wear-resistant layer 101 and the sealing layer of the powder metallurgy matrix, preventing dry friction from causing damage to the resin sealing layer, reducing wear particles, and preventing the exposure of micropores in the matrix and resulting in air leakage. At the same time as the oil film forms and flows, the centrifugal force generated by the rotation of the sweeper blade 3 and the pressure difference in the cavity will push the aged waste oil and the wear particles generated by friction to converge towards the slag discharge tank 11.

[0067] Among them, multiple sets of slag discharge troughs 11 are arranged symmetrically and inclined. The inner wall is a curved structure with one end wide and the other end narrow. It can guide, collect and accelerate the transport of wear particles. The wide end is convenient to receive waste oil and particles, and the narrow end is connected to the oil discharge chamber 12, which can improve the flow speed of oil and particles and avoid blockage. Every time the sweeping blade 3 rotates, it will push the particles and waste oil on the surface of the wear-resistant layer 101 into the corresponding slag discharge trough 11, so that the wear particles will not stay on the sealing working surface, will not form abrasive particles to aggravate wear, and will not scratch the resin sealing layer.

[0068] Finally, waste oil and wear particles flow from the narrow end of the slag discharge trough 11 into the oil discharge chamber 12. Under the suction effect of the pressure difference, due to the rotation of the sweeping blades 3, the adjacent two sets of sweeping blades 3 and the elliptical structure of the pump wall 1 together form the working chamber. One set of working chambers has a smaller internal volume, is under high pressure and discharges gas outward, while the other set is under low pressure and draws gas inward. The discharged waste oil is uniformly transported to the external treatment equipment. After the external treatment equipment cools, filters, and purifies the waste oil, it sends qualified new oil back into the oil supply chamber 121, forming a complete closed-loop cycle of oil supply, lubrication, slag collection, oil discharge, purification, and oil return. During the entire cycle, both the oil supply chamber 121 and the oil discharge chamber 12 are inclined and elongated, which can ensure smooth oil flow and stable pressure. Combined with the motion characteristics of the elliptical pump wall 1, the pump chamber is always in an ideal working state with sufficient lubrication, stable temperature, constant vacuum, and no particle accumulation.

[0069] Among them, the oil supply chamber 121 is located in the negative pressure chamber and is a low-pressure working chamber, while the oil discharge chamber 12 is located in the high-pressure chamber and is a high-pressure working chamber.

[0070] Because the pump wall 1 is made of resin-sealed powder metallurgy stainless steel, combined with the wear-resistant layer 101, stable oil supply structure and automatic slag discharge structure, it retains the advantages of high precision and low cost of powder metallurgy molding, and ensures airtightness through resin sealing. At the same time, relying on constant pressure oil supply and synchronous slag discharge structure, it achieves long service life, low wear and high stability continuous vacuum operation, which is particularly suitable for long-term reliable operation of electronic vacuum pumps.

[0071] The technical scope of this invention is not limited to the content described above. Those skilled in the art can make various modifications and variations to the above embodiments without departing from the technical concept of this invention, and all such modifications and variations should fall within the protection scope of this invention.

Claims

1. A resin-sealed powder metallurgy stainless steel vacuum pump chamber, characterized in that, The pump includes a pump wall, the inner wall of which is provided with a stabilizing component for constant pressure injection of new oil into the pump and simultaneous discharge of waste oil and wear particles, and the inner wall of the pump is provided with a wear-resistant layer. The stabilizing component includes multiple sets of slag discharge grooves opened on the inner wall of the wear-resistant layer. Multiple sets of oil supply chambers for introducing new oil from the outside to the inside are symmetrically opened on the inner wall of the wear-resistant layer. Multiple sets of oil discharge chambers for discharging waste oil and wear particles from the inside to the outside are also symmetrically opened on the inner wall of the wear-resistant layer. An orifice plate is embedded in the oil supply chamber. Multiple sets of conical holes are equally spaced on the surface of the orifice plate to reduce the flow rate of new oil and to form a relatively uniform capillary liquid surface. A seepage layer is embedded in the oil supply chamber and on one side of the orifice plate to reduce the flow rate of new oil and maintain the internal air pressure of the pump wall at a relatively constant level. The internal shape of the pump wall is elliptical.

2. The resin-sealed powder metallurgy stainless steel vacuum pump chamber according to claim 1, characterized in that: The multiple sets of slag discharge troughs are symmetrical, and the slag discharge troughs are inclined as a whole.

3. The resin-sealed powder metallurgy stainless steel vacuum pump chamber according to claim 2, characterized in that: Furthermore, the inner wall of the slag discharge trough is a curved arc shape with one end wider than the other, and a group of oil discharge chambers, oil supply chambers and slag discharge troughs that are close to each other form a circulation group.

4. The resin-sealed powder metallurgy stainless steel vacuum pump chamber according to claim 3, characterized in that: The oil discharge chamber is connected to a treatment device for cooling and purifying waste oil via an external oil circuit, and the oil discharge chamber is connected to the narrower end of the slag discharge tank.

5. The resin-sealed powder metallurgy stainless steel vacuum pump chamber according to claim 4, characterized in that: Furthermore, the oil supply chamber is connected to the processing equipment via an external oil circuit.

6. The resin-sealed powder metallurgy stainless steel vacuum pump chamber according to claim 1, characterized in that: The inner wall of one end of the oil drain chamber and the oil supply chamber is elongated and inclined at a certain angle. The other end of the oil drain chamber and the oil supply chamber are connected to a connecting pipe for external oil circuit.

7. The resin-sealed powder metallurgy stainless steel vacuum pump chamber according to claim 1, characterized in that: The main material of the infiltration layer is silicon carbide ceramic, which has high strength and relatively stable chemical properties.

8. The resin-sealed powder metallurgy stainless steel vacuum pump chamber according to claim 1, characterized in that: The inner walls at both ends of the tapered hole are frustoconical, and the opening and axial length of the tapered hole at the end closest to the pump wall are both greater than those at the other end.

9. The resin-sealed powder metallurgy stainless steel vacuum pump chamber according to claim 1, characterized in that: A rotor is installed at the center of the pump wall. Multiple sets of sweeping blades are slidably inserted into the outer wall of the rotor, and each set of sweeping blades is inclined at a certain angle. One end of the sweeping blades is in sliding contact with the inner wall of the wear-resistant layer.

10. The preparation process of the resin-sealed powder metallurgy stainless steel vacuum pump chamber according to any one of claims 1-9, characterized in that: Includes the following steps: S1. Raw material preparation and integrated pressing: Weigh 430L of water-atomized ferritic stainless steel powder, high-purity copper powder of the corresponding proportion, and an appropriate amount of molding agent according to the preset ratio, and put them into the mixing equipment for thorough mixing to obtain a uniformly dispersed mixed powder; fill the mixed powder into a precision mold that is compatible with the pump chamber foundation structure, press it under preset pressure, and slowly release the pressure after holding the pressure to demold, thereby obtaining a pump chamber green blank with an integrated elliptical inner cavity. The density and dimensional accuracy of the green blank meet the molding design requirements. S2. Vacuum sintering and precision machining: The green billet in the pump chamber is neatly placed in the sintering support fixture and sent into the vacuum sintering furnace for segmented heating and sintering in a vacuum environment. First, the temperature is raised to the low temperature range at a preset rate and held to completely remove the forming agent; then the temperature is raised to the sintering temperature range at a preset rate and held to complete the metallurgical sintering. After cooling in the furnace, the product is taken out of the furnace to obtain the pump chamber sintered matrix. The porosity and hardness of the matrix meet the design requirements. After the sintered substrate is corrected for sintering deformation by shaping mold, the basic machining of mounting holes, positioning holes and inner cavity mating surfaces is completed first. Then, the slag discharge trough, oil supply cavity and oil discharge cavity are precision shaped. After precision finishing, the dimensional accuracy, geometric tolerances and surface finish of each structure meet the design requirements of the drawings. S3. Local hardening treatment and stable component assembly: A fiber laser is used to perform local laser surface alloying treatment on the wear-resistant layer area of ​​the pump chamber wall. The entire process is protected by inert gas to avoid oxidation, resulting in a wear-resistant layer that meets the design requirements for hardness and hardened layer depth. After hardening, a low-temperature tempering treatment is performed to completely release the internal stress of processing. First, a silicon carbide ceramic diffusion layer and a perforated plate with honeycomb array conical holes are sequentially press-fitted into the oil supply chamber. After pressing, a sealing and fixing treatment is performed to ensure that the components are not loose and the oil circuit is leak-free. Then, the external oil circuit connection pipe is assembled and the corresponding interface of the connection pipe is fixedly connected to the oil supply chamber and the oil discharge chamber. The connection is sealed and reinforced to prevent leakage and air leakage in the external oil circuit. S4. Resin sealing and full-item inspection of finished products: The assembled pump chamber is subjected to ultrasonic cleaning, deionized water rinsing, and vacuum drying in sequence to thoroughly remove cutting impurities, welding fumes and moisture from the surface and pores; then the pump chamber is placed in an impregnation tank, vacuumed and pressurized, and preheated mineral oil-resistant modified epoxy resin is injected. After impregnation under negative pressure, compressed air is introduced to increase and maintain pressure to complete full-pore vacuum and pressurized sealing. The pump chamber is removed to remove excess resin from the surface. After being cured by step heating, it undergoes dehydration and rust prevention treatment. Finally, it is subjected to full-item testing for dimensional accuracy, hardness, airtightness, oil circuit continuity, and sealing quality. After passing the tests, the finished pump chamber is obtained.

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