A high-speed gear fuel pump resistant to high temperature and high pressure

Abstract

The present invention belongs to the field of aerospace fuel pump design, and specifically relates to a high-speed gear fuel pump that is resistant to high temperature and high pressure. The high-temperature gear fuel pump structure does not have a high-temperature fuel pump design, and the gear pump has no self-protection mechanism when the outlet is over-pressured during operation, which may cause the risk of damage to the fuel pump itself or even the risk of failure of the upper fuel system to supply oil. The present invention has a sealing disc body that is pressed against the mechanical seal on the outer rod portion of the drive shaft, a drive shaft oil inlet hole at the inner end portion of the drive shaft, and a drive shaft oil-slinging hole on the annular surface of the sealing disc body. The drive shaft oil inlet hole is connected to the drive shaft oil-slinging hole through the shaft hole, and the position of the drive shaft oil-slinging hole is aligned with the mechanical seal cavity; the pump casing has a pump casing oil guide hole that is connected to the mechanical seal cavity on the pipe wall of the high-pressure outlet; the pump casing has an oil return hole that is connected to the center hole of the driven gear on the cavity wall of the mechanical seal cavity. It improves the oil suction capacity of the pump, improves the volumetric efficiency, and has a significant effect on reducing cavitation and noise.

Description

Technical Field

[0001] The invention belongs to the field of aerospace fuel pump design, and in particular relates to a high-speed gear fuel pump that is resistant to high temperature and high pressure. Background Art

[0002] At present, the working medium temperature of aerospace gear pumps is generally -50℃~+150℃. The gear high-temperature fuel pump structure lacks high-temperature fuel pump reliability and safety design. This will cause the gear pump to have no self-protection mechanism when the outlet is overpressured during operation, which may cause the risk of damage to the fuel pump itself or even the risk of failure of the upper fuel system's oil supply.

[0003] For an operating environment with an ambient temperature requirement of +250℃~+350℃ and a maximum medium fuel temperature of 225℃±10℃, conventional sealing leather cups cannot withstand the high oil temperature at 150℃ in a short period of time and the huge heat generated by the close contact and rotation of the drive shaft and the sealing leather cup, and fail to function and lose their sealing function, causing oil leakage in the fuel pump.

[0004] In actual operation, mechanical seals used when the working temperature exceeds 150°C are called high-temperature mechanical seals. The high-temperature working environment will cause the end face liquid film to vaporize, the material to deteriorate, aggravate the corrosion of the mechanical seal, cause large thermal deformation and other problems, thereby making the high-temperature pump mechanical seal lose its effectiveness. Summary of the Invention

[0005] The purpose of the present invention is to propose a high-speed gear fuel pump that is resistant to high temperature and high pressure, can withstand a medium temperature of 225°C and an ambient temperature of +250°C to +350°C, has a reliability and safety design, and has the ability to work for a long time under extreme high temperatures.

[0006] The high-speed gear fuel pump resistant to high temperature and high pressure of the present invention includes a driving gear, a driven gear, a transmission shaft and other components installed in a pump casing and a pump cover. The outer rod portion of the transmission shaft has a sealing disc body pressed against a mechanical seal. The transmission shaft has a transmission shaft oil inlet hole at the inner end portion and a transmission shaft oil-slinging hole on the annular surface of the sealing disc body. The transmission shaft oil inlet hole is connected to the transmission shaft oil-slinging hole through an axial hole, and the position of the transmission shaft oil-slinging hole is aligned with the mechanical seal cavity; a "human" hole is provided on the inner end surface of the pump cover, connecting the center hole of the gear pair and the axial hole of the transmission shaft; a pump casing oil guide hole connected to the mechanical seal cavity is opened on the pipe wall of the high-pressure outlet of the pump casing; and an oil return hole connected to the center hole of the driven gear is opened on the cavity wall of the mechanical seal cavity.

[0007] Advantageously, the driving gear is fixed by an active floating bearing assembly and an active fixed bearing assembly, and the driven gear is fixed by a driven floating bearing assembly and a driven fixed bearing assembly, and each bearing assembly has a double spiral groove on the inner surface of the winding sleeve in contact with the gear shaft.

[0008] Advantageously, the size and material of the bearing assembly are such that after expansion in a high temperature environment, the gap between the bearing assembly and the pump housing is larger than the gap between the bearing assembly and the transmission shaft.

[0009] Advantageously, the mechanical seal includes an annular mechanical seal housing with an annular groove at one end, in which a cylindrical spring, a baffle and a graphite static ring are installed in sequence, and the graphite static ring is fixed by a spring clamp ring. The inner ring surface of the graphite static ring and the annular groove are sealed by a fourth O-ring, and the end face of the graphite static ring is in close contact with the sealing surface of the sealing disc body.

[0010] Advantageously, the mechanical seal is fixedly mounted on the pump housing via a retaining ring.

[0011] Advantageously, a high-temperature safety valve is also connected to the pump housing, and a valve core, a valve spring, a gasket and a valve cover are sequentially installed in the valve housing.

[0012] Advantageously, the inner end of the transmission shaft is provided with a gear spline, which is connected to the driving gear; and the outer end of the transmission shaft is provided with a motor spline, which is connected to the motor.

[0013] Advantageously, compensation springs are respectively installed on the active floating bearing assembly and the passive floating bearing assembly, a first O-ring is installed on the active floating bearing assembly, and a second O-ring is installed on the passive floating bearing assembly; a first rectangular sealing ring is installed on the active fixed bearing assembly, and a second rectangular sealing ring is installed on the passive fixed bearing assembly.

[0014] Advantageously, the pump cover is screwed through screw holes on the pump cover and connected to the pump housing, and is sealed by a third O-ring.

[0015] Advantageously, the pump housing 4 is made of TA15 material, the bearings of each bearing assembly are made of QSn4-3 material, and the bearing seal and end face seal are made of high-temperature resistant rubber material FM-2D.

[0016] Designing the heat dissipation characteristics of the internal circulation of the fuel system, the operating environment temperature of the fuel pump is relatively high, so only conductive heat dissipation can be used to reduce the heat in the mechanical seal cavity; by absorbing the heat from the mechanical seal cavity through the medium oil, reducing the heat in the mechanical seal cavity can effectively alleviate the damage to the mechanical seal in the high temperature and high pressure environment and extend its service life.

[0017] The invention is a measure for heat dissipation in the internal circulation of the fuel pump. A channel is designed from the spline inside the driving gear to the mating disc of the drive shaft. Four through-holes with a diameter of 1mm and an angle of 90° to each other are opened on the mating surface disc to form a passage so that the oil can directly reach the mechanical seal cavity from the inlet. The inlet oil enters the V-groove through the inlet hole, and then enters the center hole of the drive shaft spline through the center of the driving gear. The oil is pressurized and thrown into the mechanical seal cavity by the high-speed rotation of the drive shaft. Based on Bernoulli's principle, this method accelerates the oil circulation in the pump and promotes heat dissipation in the mechanical seal cavity.

[0018] To efficiently absorb the friction heat of the mechanical seal and extend its service life, an oil inlet hole is designed at the outlet of the fuel pump to drain the outlet high-pressure oil into the mechanical seal chamber. After entering the mechanical seal chamber, this part of the high-pressure oil absorbs the heat of the mechanical seal and then flows back to the inlet through the oil return hole, significantly improving the heat dissipation efficiency of the mechanical seal friction heat.

[0019] Self-lubricating rolled sleeves are used to open double spiral grooves for lubrication. The bearings serve as the supporting parts of the gear shaft. When the gear pump runs at high speed, a large amount of heat will be generated due to rapid friction. The double spiral grooves can ensure that the bearings of the pump obtain a large amount of lubricating oil under high speed conditions, reduce bearing wear, improve transmission efficiency, form a dynamic pressure oil film, and take away the heat of the bearings through the continuous circulation of oil, which can well solve the temperature rise problem of the bearings and play a good lubricating and cooling role for the bearings.

[0020] Specific high-temperature resistant materials are used to meet the requirements of long-term high-temperature operation of the high-temperature fuel pump; the pump housing is made of TA15 material, the bearings are made of QSn4-3 material, and the bearing seals and end face seals are made of high-temperature resistant rubber material FM-2D.

[0021] Beneficial effects: The present invention further increases the fuel pump medium temperature to +225°C, the ambient temperature is +250°C to +350°C, the operating speed breaks through the traditional 11500rpm limit to reach 15000rpm, the fuel pump outlet pressure is as high as 7.5MPa, and the efficiency reaches 60%-75%.

[0022] This solution extends the service life of the mechanical seal and improves the efficiency of the fuel pump under high-temperature conditions. When the high-temperature safety valve reaches the set opening pressure, it opens, creating an internal circulation from the outlet to the return high-temperature safety valve, protecting the fuel pump from damage. Designed for high-speed, high-temperature operating environments, the bearings are lubricated using a low-pressure lubrication method with inlet oil suction. This method produces a large flow of lubricating oil, high viscosity, and excellent conditions for oil film formation. The dynamic oil film has a strong load-bearing capacity and can continuously circulate the oil to remove heat from the bearings, significantly improving the pump's oil absorption capacity. This not only increases volumetric efficiency but also significantly reduces cavitation and noise. To prevent potential failures in high-speed environments with high outlet pressures, high temperatures, and high speeds, a high-temperature safety valve for the fuel pump can effectively improve the safety and reliability of the fuel pump during high-temperature operation.

[0023] The structure is reasonable, the material selection complies with relevant industry standards, the quality is stable and reliable, and the reliability and safety are good, which can meet the long-term working requirements under the conditions of 225℃ medium temperature and +250℃~+350℃ ambient temperature. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 1 is an exploded schematic diagram of the high-speed gear fuel pump of the present invention;

[0025] Figure 2 It is a schematic diagram of the structure of the pump casing;

[0026] Figure 3 It is a schematic diagram of the oil guide hole of the pump casing;

[0027] Figure 4 This is a schematic diagram of the high temperature safety valve;

[0028] Figure 5 It is a structural diagram of the transmission shaft;

[0029] Figure 6 It is a cross-sectional view of the drive shaft;

[0030] Figure 7 It is a structural diagram of the pump cover;

[0031] Figure 8 It is a schematic diagram of the structure of a mechanical seal;

[0032] Figure 9 It is a structural diagram of a double helical groove wound sleeve.

[0033] Among them, 1- retaining ring, 2- mechanical seal, 3- transmission shaft, 4- pump housing, 5- compensation spring, 6A- first O-type sealing ring, 6B- second O-type sealing ring, 7A- active floating bearing assembly, 7B- driven floating bearing assembly, 8A- driving gear, 8B- driven gear, 9A- active fixed bearing assembly, 9B- driven fixed bearing assembly, 10A- first rectangular sealing ring, 10B- second rectangular sealing ring, 11- third O-type sealing ring, 12- pump cover, 13- screws, 14- high temperature safety valve, 15- valve cover, 16- Gasket, 17-valve spring, 18-valve core, 19-valve housing, 100-drive shaft oil inlet hole, 101-drive shaft oil throwing hole, 102-gear spline, 103-sealing surface, 104-motor spline, 105-"human" hole, 106-screw hole, 107-spring retaining ring, 108-fourth O-ring, 109-graphite static ring, 110-mechanical seal housing, 111-baffle, 112-cylindrical spring, 113-double spiral groove, 401-compensation spring hole, 402-safety valve inlet, 403-pump housing oil guide hole DETAILED DESCRIPTION

[0034] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative work are within the scope of protection of the present invention.

[0035] The features and illustrative embodiments of various aspects of the present invention will be described in detail below. In the detailed description below, many specific details are proposed in order to provide a comprehensive understanding of the present invention. However, it will be apparent to those skilled in the art that the present invention can be implemented without the need for some of these specific details. The following description of the embodiments is merely intended to provide a better understanding of the present invention by illustrating examples of the present invention. The present invention is in no way limited to any specific arrangement and method proposed below, but rather encompasses any improvements, replacements, and modifications to structures, methods, and devices without departing from the spirit of the present invention. In the accompanying drawings and the following description, well-known structures and techniques are not shown to avoid unnecessary ambiguity in the present invention.

[0036] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other, and the embodiments can refer to and quote each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0037] refer to Figure 1 The present invention mainly consists of 1-retaining ring, 2-mechanical seal, 3-transmission shaft, 4-pump housing, 5-compensation spring, 6A-first O-type sealing ring, 6B-second O-type sealing ring, 7A-active floating bearing assembly, 7B-driven floating bearing assembly, 8A-driving gear, 8B-driven gear, 9A-active fixed bearing assembly, 9B-driven fixed bearing assembly, 10A-first rectangular sealing ring, 10B-second rectangular sealing ring, 11-third O-type sealing ring, 12-pump cover, 13-screws, and 14-high-temperature safety valve.

[0038] In some embodiments, a retaining ring 1 secures the mechanical seal 2 to prevent it from shaking. The pump housing 4 includes two oil well bores and a safety valve chamber. The driving gear 8A and the driven gear 8B are a pair of externally meshing spur gears. The active fixed bearing assembly 9A, the driving gear 8A, and the active floating bearing assembly 7A are assembled and installed in one oil well bore. The passive fixed bearing assembly 9B, the driven gear 8B, and the passive floating bearing assembly 7B are assembled and installed in the other oil well bore. Compensation springs 5 ​​are positioned at the ends of the active and passive floating bearing assemblies 7A and 7B. The splined end of the drive shaft 3 mates with the splined end of the driving gear 8A. The other end of the drive shaft 3 is assembled with the mechanical seal 2 to form a dynamic seal structure. A high-temperature safety valve 14 is installed in the safety valve chamber of the pump housing 4.

[0039] In some embodiments, a driving gear 8A and a driven gear 8B are meshed with each other in the oil well hole of the pump housing 4. An active floating bearing assembly 7A and a driven floating bearing assembly 7B are respectively installed on one end of the driving gear 8A and the driven gear 8B, and an active fixed bearing assembly 9A and a driven fixed bearing assembly 9B are respectively installed on the other end. A compensation spring is installed on the other end of the active floating bearing assembly 7A and the driven floating bearing assembly 7B. The transmission shaft 3 is splined with the driving gear 8A, and the other end is connected to the mechanical seal 2 to form a dynamic sealing structure.

[0040] In some embodiments, the pump housing 4 is designed and processed with an oil guide hole 403 with a diameter of 0.5mm to 1mm between the pump body outlet and the mechanical seal groove to guide the outlet high-pressure oil medium, so as to absorb the heat from the mechanical seal 2 and the transmission shaft sealing surface 103; the size of the oil guide hole can be further determined according to the actual working conditions. Here, the optimal size is adopted that does not affect the outlet pressure and cause pressure relief, while meeting the heat dissipation flow requirements in the mechanical seal cavity.

[0041] In some embodiments, a high-temperature safety valve 14 is installed within the safety valve cavity of the pump housing 4 to protect the outlet pressure. The high-temperature safety valve 14 comprises a valve cover 15, a valve housing 19, a valve core 18, a spring 17, and a gasket 16. When the high-temperature safety valve reaches a critical pressure, it opens to relieve pressure at the outlet, protecting the internal components of the gear pump from damage and preventing abnormal conditions.

[0042] In some embodiments, the mechanical seal 2 comprises a sealing pump housing 110, a graphite stationary ring 109, a cylindrical spring 112, a spring retaining ring 107, a baffle 111, and a fourth O-ring 108. The mechanical seal prevents fluid flow through the relatively stationary graphite end face by creating close contact and friction with the high-speed rotating metal end face. By optimizing the contact surface between the graphite stationary ring 109 and the drive shaft 3, frictional heat generated by friction in this area can be reduced, thereby extending the service life of the mechanical seal 2.

[0043] In some embodiments, the drive shaft 3 has an oil-swing hole 101 at the spline 102 connecting to the driving gear 8A. This hole allows the medium, after high-speed rotation and pressurization, to be spun into the mechanical seal chamber, absorbing frictional heat between the mechanical seal and the drive shaft. The small spline 102 of the drive shaft connects to the driving gear 8A, while the large spline 104 connects to the motor main shaft.

[0044] In some embodiments, the pump cover 12 is provided with a herringbone hole, which is coaxial with the master / driven gears 8A and 8B, enhancing the fluidity of the medium and forming a passage to promote the internal circulation of heat generated in the gears, bearings, transmission shafts and mechanical seals.

[0045] In some embodiments, a compensating spring 5 is provided at one end of floating bearing assemblies 7A and 7B. The compensating spring force causes the working surfaces of floating bearing assemblies 7A and 7B to contact the end faces of gears 8A and 8B, thereby eliminating end-face clearance. Because floating bearing assemblies 7A and 7B float axially along the gears, they can continuously compensate for gaps that increase due to wear.

[0046] In some embodiments, rectangular unloading grooves are provided on the end faces of the bearing assemblies 7A, 7B, 9A, and 9B that contact the tooth surfaces to eliminate local oil trapping in the bearings, and a molybdenum disulfide coating is applied to the end faces to reduce friction between the gears and the bearings, thereby improving the mechanical efficiency of the present invention.

[0047] The present invention proposes a novel ultra-high temperature and high pressure resistant high-speed gear pump, which includes a pump casing 4. A pair of externally meshing master / slave spur gears 8A and 8B are provided in the pump casing 4. At the oil inlet of the oil pump, the meshing gear teeth gradually disengage, the volume of the gear tooth valley cavity increases, and the volume of the sealed working chamber continues to increase, forming a local vacuum. The fuel is sucked into the pump, completing the oil suction process. At the same time, at the oil outlet of the oil pump, the gear teeth gradually engage, the volume of the gear tooth valley cavity decreases, the volume of the sealed working chamber continues to decrease, and the fuel in the tooth valley is squeezed to the outlet, completing the oil pressure process.

[0048] Floating bearing assemblies 7A and 7B are mounted on one end face of the driving / driven gears 8A and 8B, and fixed bearing assemblies 9A and 9B are mounted on the other end faces. The active fixed bearing assembly 9A, the driving gear 8A, and the active floating bearing assembly 7A form a stepped series and are mounted in the oil well bore of the pump casing 4. The driven fixed bearing assembly 9B, the driven gear 8B, and the driven floating bearing assembly 7B form a stepped series and are mounted in another oil well bore. A compensation spring 5 is mounted on the other end of the floating bearing assemblies 7A and 7B and is installed in the spring hole of the pump casing. Axial play in high-pressure gear pumps can lead to flow loss, so eccentric floating bearing assemblies 6A and 6B are used to automatically compensate for axial play and prevent bearing tilt. Since there is no high-pressure oil in the discharge chamber during pump startup, a compensation spring 5 is installed on one side of the floating bearing assemblies 7A and 7B to ensure that end play is compensated during pump startup. O-rings 6A and 6B are also installed on the floating bearings 7A and 7B. When the pump is in operation, the outlet oil passes through the high-pressure oil inlet holes in the floating bearings 7A and 7B and acts on the other end surface of the floating bearings 7A and 7B, thereby automatically compensating for the end surface clearance of the fuel pump in the operating state.

[0049] An internal spline is designed within the axis of driving gear 8A. External splines 102 on drive shaft 3 mate with the internal splines of driving gear 8A. External splines 104 are connected to the motor shaft. Sealing surface 103 contacts the graphite stationary ring 109 in mechanical seal 2, forming a dynamic seal structure. The medium oil enters the transmission shaft oil-slinging hole 101 through the oil-slinging hole channel 100 on transmission shaft 3 and flows out to the mechanical seal chamber, increasing the oil flow and dissipating heat from the mechanical seal contact sealing surface 103. Inlet oil enters the annular groove through the inlet hole, then enters the center hole of the driving gear and into the center hole of the transmission shaft. Finally, the oil is ejected under the high-speed rotation of the transmission shaft. The high-speed rotation of the transmission shaft generates centrifugal force that pressurizes the oil entering the transmission shaft. The pressurized oil is ejected into the mechanical seal to absorb frictional heat from the mechanical seal. This method, based on Bernoulli's principle, accelerates oil circulation within the pump, forming one of the mechanisms for the fuel pump's heat dissipation characteristics.

[0050] The outlet high-pressure oil is led to the mechanical seal chamber. This part of the high-pressure oil quickly enters the mechanical seal chamber and absorbs the heat in the seal chamber before returning to the inlet through the oil return hole, greatly improving the heat dissipation efficiency in the mechanical seal chamber. The oil inlet hole is located in the passage from the high-pressure outlet of the fuel pump to the mechanical seal. Its function is to allow the fuel in the fuel pump to flow to the mechanical seal to absorb heat, then return through the oil return hole and the center hole of the driven gear through the human-shaped groove on the pump cover, and then flow into the fuel pump inlet to form a loop. As shown in the attached figure, the pump housing 4 outlet is designed with a pump housing oil guide hole 403. Its function is to lead the high-pressure oil at the outlet to the mechanical seal to dissipate heat for the mechanical seal sealing surface 103. The medium absorbs the friction heat at the mechanical seal and enters the pump housing oil return hole. After passing through the oil return hole, it returns through the center hole of the driven gear 7B to the "human" hole 105 on the pump cover, and then returns to the inlet of the pump housing 4, forming a total heat dissipation circulation loop.

[0051] Mechanical seal 2 prevents fluid flow through the relatively stationary graphite end face, which creates close contact and friction with the rapidly rotating metal end face. Structurally, a graphite stationary ring 109 is in close contact with the sealing surface 103 of the transmission shaft 3. The compression force of a cylindrical spring 112 compresses the graphite stationary ring 109 against the sealing surface 103 of the transmission shaft 3. The retaining ring 1 secures the mechanical seal 2 axially. The operating medium temperature range of mechanical seal 2 is -40°C to +225°C, ensuring a sealing effect sufficient for the high-temperature, long-term operation of high-temperature fuel pumps.

[0052] A high-temperature safety valve structure connected with high-temperature bolts is designed for pressure protection. The changes in the mechanical properties of the objects connected by the bolts under high temperature conditions are taken into account, so that its stress management can be consistent with the actual situation. Furthermore, to further prevent thread failure under high temperature conditions, it is necessary to scientifically select materials so that the threads are designed to have a coarse thread state, which can increase the gap stitching strength in the middle within a reasonable range, ensure that the remaining warning force is higher than the required value, and ensure the stability and professionalism of the connection. The high-temperature safety valve consists of a valve cover 15, a valve housing 19, a valve core 18, a spring 17, and a gasket 16. When the high-temperature safety valve reaches the set opening pressure, it opens to relieve pressure at the outlet, reducing the pressure damage at the fuel pump's own outlet and avoiding destructive failures in the upper fuel system.

[0053] The bearing assembly is lubricated using a self-lubricating rolled sleeve. Made from a rolled metal-plastic self-lubricating sheet, the rolled sleeve provides lubrication and friction reduction. The self-lubricating metal-plastic rolled bearing, with a polytetrafluoroethylene composite material as the self-lubricating layer and a low-carbon steel plate as the pressure-bearing layer, is suitable for light-load, high-speed environments. It exhibits an extremely low coefficient of friction from room temperature to 260°C, and boasts an exceptionally long wear life in fluid media such as water and oil, providing lubrication and friction reduction.

[0054] Double spiral grooves 113 are machined in the rolled sleeve. This double spiral groove structure 113 can obtain a considerable lubricating oil flow rate, a large amount of oil entering the bearing, high oil viscosity, good oil film formation conditions, and a strong load-bearing capacity of the dynamic pressure oil film; the heat of the bearing can be taken away by the continuous circulation of the oil, which can well solve the temperature rise problem of the bearing and play a good lubricating and cooling role for the bearing; a large amount of oil is used to fill the root of the gear that has just disengaged, which greatly improves the oil suction performance of the pump and avoids the air suction phenomenon. It can not only improve the volumetric efficiency, but also has a significant effect on reducing cavitation and noise.

[0055] The present invention also includes some other accessories. The rectangular sealing rings 10A and 10B are made of high-temperature resistant material FM-2D, which are installed in the fixed bearing sealing groove and are used for sealing between the bearing and the pump chamber. The O-ring 11 is made of high-temperature resistant material FM-2D, which is installed in the sealing groove of the pump casing 4 and is used for sealing between the pump cover 12 and the pump casing 4. The pump cover 12 is installed on the pump casing 4 by screws 13, ensuring good liquid tightness and safety.

[0056] The design features of the present invention can be summarized as follows, which combine to achieve the technical effects of the present invention:

[0057] 1. High temperature sealing structure

[0058] The external splines of the drive shaft connect to the external drive motor shaft, and the drive shaft seal disc and the graphite stationary ring in the mechanical seal tightly fit together to form a dynamic seal structure. The graphite stationary ring of the mechanical seal closely contacts and rubs against the sealing surface of the high-speed rotating drive shaft to prevent the flow of fluid through this end face, forming a seal.

[0059] 2. Heat dissipation through oil-spraying holes

[0060] An internal spline is designed inside the driving gear shaft. The inlet oil of the pump casing enters the manifold through the inlet hole and then enters the transmission shaft through the center hole of the driving gear. The medium oil passes through the oil inlet hole of the transmission shaft and then through the oil throwing hole of the transmission shaft. After the transmission shaft rotates at high speed and pressurizes, the oil is thrown out to the mechanical seal cavity, increasing the oil inlet amount of the mechanical seal cavity to dissipate heat from the mechanical seal. According to the Bernoulli principle, this method accelerates the oil circulation in the pump, forming one of the heat dissipation characteristic mechanisms of the fuel pump.

[0061] 3. Heat dissipation through oil holes

[0062] The outlet high-pressure oil is introduced into the mechanical seal chamber through the oil guide hole of the pump casing. After entering the mechanical seal chamber, this part of the high-pressure oil absorbs the heat in the seal chamber and flows through the oil return hole, the center hole of the driven gear, the man-shaped groove of the pump cover, and finally returns to the inlet, greatly improving the heat dissipation efficiency in the mechanical seal chamber.

[0063] 4. High temperature safety valve

[0064] A high-temperature safety valve structure designed for pressure protection uses high-temperature bolt connections. The bolts, when exposed to high temperatures, take into account the changes in mechanical properties of the objects they connect, ensuring stress management tailored to the actual situation. Furthermore, to further prevent thread failure at high temperatures, scientific material selection is essential. The threads are designed with a coarse pitch, which increases the gap strength within a reasonable range, ensuring the remaining warning force exceeds the required value, and ensuring a secure and professional connection. The high-temperature safety valve consists of a valve cover 15, a valve housing 19, a valve core 18, a spring 17, and a gasket 16. When the high-temperature safety valve reaches the set opening pressure, it opens to relieve pressure at the outlet, reducing pressure buildup at the fuel pump outlet and preventing destructive failures in the upstream fuel system. This fuel pump structure is suitable for media temperatures up to 225°C, therefore maximizing product safety and reliability. Safety design is essential for the fuel pump in the event of a problem at the fuel pump outlet. A safety valve is opened at the shell outlet. When the pressure at the fuel pump outlet exceeds the normal working requirements of the fuel pump, the safety valve opens and the medium flows back to the pump inlet through the safety valve to form a medium circulation path in the pump to release the pressure in time to prevent the internal structure of the fuel pump from being damaged by the pressure.

[0065] When bolting high-temperature valves, the changes in the mechanical properties of the objects being bolted must be considered at high temperatures, ensuring that stress management is consistent with actual conditions. Furthermore, to further prevent thread failure at high temperatures, scientific material selection is necessary, with the thread designed to have a coarse pitch. This allows for increased gap strength within a reasonable range, ensuring the remaining warning force exceeds the required value, and ensuring the connection is stable and professional. Furthermore, an appropriate gap must be maintained between the sealing seat on the safety valve, based on existing practical conditions, ensuring that the thermal expansion and contraction of the material is greater than the thermal expansion and contraction of the material. Otherwise, wear and tear problems may occur.

[0066] 5. Double helix groove

[0067] The bearing assembly is lubricated using a self-lubricating rolled sleeve. The rolled sleeve is made of a metal-plastic self-lubricating sheet material, which provides lubrication and friction reduction. The self-lubricating metal-plastic rolled bearing, which uses a polytetrafluoroethylene composite material as the self-lubricating layer and a low-carbon steel plate as the pressure-bearing layer, is suitable for light-load, high-speed environments. It has an extremely low coefficient of friction from room temperature to 260°C and offers an exceptionally long wear life in fluid media such as water and oil, providing lubrication and friction reduction. Double helical lubrication grooves 113 are machined into the rolled sleeve. This double helical lubrication groove structure 113 ensures a significant flow of lubricating oil, allowing a large amount of oil to enter the bearing, resulting in high oil viscosity, good oil film formation conditions, and a strong dynamic pressure oil film load-bearing capacity. The oil continuously circulates to remove heat from the bearing, effectively addressing the issue of bearing temperature rise and providing excellent lubrication and cooling for the bearing. A large amount of oil fills the root of the newly disengaged gear, significantly improving the pump's oil absorption performance and avoiding cavitation. This not only improves volumetric efficiency but also significantly reduces cavitation and noise. This high-temperature pump structure is suitable for ultra-high-temperature medium oils. Considering the additional increase in lubricating oil volume and bearing heat caused by a single spiral groove in the bearing bore, a double spiral groove structure is adopted to increase the oil flow into the bearing spiral grooves. Double spiral grooves are installed in the inner bores of both the floating and fixed bearings. Gears at high speeds and high pressures require more oil for lubrication, absorption, and heat dissipation. A single spiral groove is no longer sufficient for ultra-high-temperature medium use. Theoretical analysis and actual testing have confirmed that the addition of double spiral grooves can effectively increase the amount of oil entering the spiral grooves.

[0068] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the field can easily think of various equivalent modifications or replacements within the technical scope disclosed by the present invention, and these modifications or replacements should all be covered by the scope of protection of the present invention.

Claims

1. A high-speed gear fuel pump resistant to high temperature and high pressure, comprising a driving gear (8A), a driven gear (8B) and a transmission shaft (3) mounted in a pump housing (4) and a pump cover (12), characterized in that: The outer rod portion of the transmission shaft (3) has a sealing disc body pressed against the mechanical seal (2), and the working medium temperature range of the mechanical seal (2) is -40°C to +225°C. The transmission shaft (3) has a transmission shaft oil inlet hole (100) at the inner end portion, and a transmission shaft oil-slinging hole (101) on the annular surface of the sealing disc body. The transmission shaft oil inlet hole (100) is connected to the transmission shaft oil-slinging hole (101) through the internal shaft hole of the transmission shaft (3), and the position of the transmission shaft oil-slinging hole (101) is aligned with the mechanical seal cavity; a "human" hole (105) is provided on the inner end surface of the pump cover (12), connecting the center hole of the gear pair and the internal shaft hole of the transmission shaft (3); the pump housing (4) has a pump housing oil guide hole (403) connected to the mechanical seal cavity on the pipe wall of the high-pressure outlet; and the pump housing (4) has an oil return hole connected to the center hole of the driven gear (8B) on the cavity wall of the mechanical seal cavity.

2. The high-temperature and high-pressure resistant high-speed gear fuel pump according to claim 1, characterized in that: The driving gear (8A) is fixed by an active floating bearing assembly (7A) and an active fixed bearing assembly (9A), and the driven gear (8B) is fixed by a driven floating bearing assembly (7B) and a driven fixed bearing assembly (9B). Each bearing assembly has a double spiral groove (113) on the inner surface of a rolled sleeve in contact with the gear shaft.

3. The high-temperature and high-pressure resistant high-speed gear fuel pump according to claim 2, characterized in that: The size and material of the bearing assembly must ensure that after expansion in a high-temperature environment, the gap between the bearing assembly and the pump housing (4) is larger than the gap between the bearing assembly and the transmission shaft (3).

4. The high-temperature and high-pressure resistant high-speed gear fuel pump according to any one of claims 1 to 3, characterized in that: The mechanical seal (2) includes an annular mechanical seal housing (110) having an annular groove at one end, in which a cylindrical spring (112), a baffle (111) and a graphite static ring (109) are sequentially installed, and the graphite static ring (109) is fixed by a spring retaining ring (107), the inner ring surface of the graphite static ring (109) and the annular groove are sealed by a fourth O-ring (108), and the end face of the graphite static ring (109) is in close contact with the sealing surface (103) of the sealing disc body.

5. The high-temperature and high-pressure resistant high-speed gear fuel pump according to any one of claims 1 to 3, characterized in that: The mechanical seal (2) is fixedly mounted on the pump housing (4) via a retaining ring (1).

6. The high-temperature and high-pressure resistant high-speed gear fuel pump according to any one of claims 1 to 3, characterized in that: A high-temperature safety valve (14) is also connected to the pump housing (4). The high-temperature safety valve (14) has a valve core (18), a valve spring (17), a gasket (16) and a valve cover (15) installed in sequence in a valve sleeve (19).

7. The high-temperature and high-pressure resistant high-speed gear fuel pump according to any one of claims 1 to 3, characterized in that: The inner end of the transmission shaft (3) is provided with a gear spline (102) connected to the driving gear (8A); the outer end is provided with a motor spline (104) connected to the motor.

8. The high-temperature and high-pressure resistant high-speed gear fuel pump according to any one of claims 2-3, characterized in that: Compensation springs (5) are also installed on the active floating bearing assembly (7A) and the passive floating bearing assembly (7B), respectively. A first O-type sealing ring (6A) is installed on the active floating bearing assembly (7A), and a second O-type sealing ring (6B) is installed on the passive floating bearing assembly (7B). A first rectangular sealing ring (10A) is installed on the active fixed bearing assembly (9A), and a second rectangular sealing ring (10B) is installed on the passive fixed bearing assembly (9B).

9. The high-speed gear fuel pump resistant to high temperature and high pressure according to any one of claims 1 to 3, characterized in that: The pump cover (12) is connected to the pump housing (4) by screws (13) passing through screw holes (106) on the pump cover (12) and is sealed by a third O-ring (11).

10. The high-temperature and high-pressure resistant high-speed gear fuel pump according to any one of claims 1 to 3, characterized in that: The pump housing (4) is made of TA15 material, the bearings of each bearing assembly are made of QSn4-3 material, and the bearing seal and end face seal are made of high temperature resistant rubber material FM-2D.

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