A composite structure gear pump

Abstract

The present invention belongs to the technical field of fluid machinery structures, and particularly relates to a composite gear pump structure. It comprises a pair of external meshing involute gear pumps and several pairs of internal meshing cycloid gear pumps. The external meshing involute gear pumps comprise a driving gear, a driven gear, a driving gear shaft, and a driven gear shaft. The driving gear shaft and the driven gear shaft are mounted on a lubricating oil pump mounting seat, with the driving gear mounted on the driving gear shaft and the driven gear mounted on the driven gear shaft. During operation, the driving gear shaft drives the driving gear and several pairs of internal meshing cycloid gear pumps mounted thereon to rotate in phase, the driving gear drives the driven gear to rotate in the opposite direction, the driven gear drives the driven gear shaft to rotate in phase, and the driven gear shaft drives several pairs of internal meshing cycloid gear pumps mounted thereon to rotate in phase. The present invention increases the operating speed range of the external meshing involute gear pump and shortens the axial length of the internal meshing cycloid gear pump to meet the design requirements of high-speed, high-flow lubricating oil pumps.

Description

Technical Field

[0001] The present invention belongs to the technical field of fluid mechanical structures, relates to a lubricating oil structure, and in particular to a composite gear pump structure. Background Art

[0002] The lubricating oil pump is the core component of the mechanical lubrication system. Its function is to circulate the lubricating oil continuously in the lubrication system to achieve lubrication and cooling of gears, bearings and other parts in the mechanical transmission system.

[0003] The external meshing involute gear pump is a common positive displacement oil pump and is widely used in aviation lubrication systems. Figure 1 , where 1 is the driving gear, 2 is the driven gear, 3 is the housing, 4 is the lubricating oil inlet provided on the housing 3, and 5 is the lubricating oil outlet provided on the housing 3. When the driving gear 1 rotates clockwise, it drives the driven gear 2 to rotate counterclockwise. On the lubricating oil inlet 4 side, as the gears continuously exit meshing, the cavity in the tooth valley is emptied, and the pressure in the cavity is lower than the pressure at the inlet. The lubricating oil is sucked into the pump and fills the cavity in the tooth valley. As the gears continue to rotate, the liquid is brought into the cavity on the outlet side 5; the teeth on the outlet side enter meshing, and when the gear teeth of one gear enter the tooth valley of another gear, the cavity volume of the tooth valley gradually decreases, and the oil in the tooth valley is squeezed toward the outlet 5. As the gears continue to rotate, the volume of the tooth valley alternates from increasing to decreasing, so that the gear pump can continuously draw oil from the low-pressure lubricating oil inlet 4 and continuously supply oil to the high-pressure lubricating oil outlet 5.

[0004] The internal meshing cycloid gear pump is another type of positive displacement oil pump widely used in aviation lubrication systems. Figure 2 , where 1 is the driving gear (inner rotor), O1 is the rotation center of the driving gear, 2 is the driven gear (outer rotor), O2 is the rotation center of the driven gear, 6 is the lubricating oil inlet side, and 7 is the lubricating oil outlet side. When the driving gear 1 rotates clockwise, it drives the driven gear 2 to rotate eccentrically in the same direction. On the lubricating oil inlet side 6, due to the rotation of the gear, the cavity between the two teeth continues to grow larger, and the pressure in the cavity is lower than the pressure at the inlet. The lubricating oil is sucked into the pump and filled into the cavity. When the gear continues to rotate, the liquid is brought into the cavity on the outlet side 7; the volume of the two tooth cavities on the side of the outlet cavity gradually decreases, and the oil in the cavity is squeezed toward the outlet. During the continuous rotation of the gear, the volume of the two tooth cavities continuously increases and decreases alternately, so that the gear pump can continuously absorb oil from the low-pressure lubricating oil inlet 6 and continuously supply oil to the high-pressure lubricating oil outlet 7.

[0005] The main problem with external involute gear pumps is that when the gear pump speed exceeds a certain value, the tangential velocity at the tooth top can reach tens to hundreds of meters per second due to the rapid rotation of the gears. Given the limited size of the gear pump's inlet chamber, the gear valleys spend too little time in the low-pressure inlet chamber, allowing the liquid to pass through the inlet chamber before the valleys are fully filled. This results in insufficient liquid in the valleys. Furthermore, if the pump speed is too high, the liquid entering the valleys rotates with the gears, generating centrifugal force that attempts to eject the liquid from the valleys. At this point, if the pump's inlet pressure is insufficient, the centrifugal force prevents the liquid from filling the valleys, similarly causing insufficient filling. This significantly reduces the pump's volumetric efficiency, lowering actual oil delivery and, in severe cases, causing cavitation, which can affect pump operation. This phenomenon is particularly pronounced during high-altitude flight, as atmospheric pressure decreases with increasing altitude, further exacerbating the inlet pressure conditions of the oil pump. Therefore, the external meshing involute gear pumps used in aviation generally have a low speed, usually not higher than 4000 rpm, which limits the application of high-speed external meshing involute gear pumps.

[0006] The main problem with internal cycloidal gear pumps is that as the gear pump speed increases, the gear pump diameter becomes thinner to reduce the linear velocity of the gears and maintain proper filling performance. This results in a smaller oil pump displacement, requiring a very long pump to maintain a certain flow rate. The slender structure of the oil pump not only increases the difficulty of part machining but also requires a larger installation space, exacerbating strength issues when cantilevered. This, to a certain extent, limits the use of high-speed, high-flow internal cycloidal gear pumps.

[0007] Patent CN104266062A discloses a gear oil pump (a patent filed in 2014), comprising an oil pump housing, a driving gear, and a driven gear. The driving gear and the driven gear mesh with each other to form a meshing transmission chain and are installed in a closed oil pump housing. Oil holes are provided on the oil pump housing at the tangent position of each pair of gear meshing. The outer contour of the transmission gear pair matches the inner cavity of the oil pump housing. There is one driving gear and more than two driven gears. This patent adopts a conventional parallel design. On the one hand, the parallel design has a larger cross-section (windward surface) and a complex inlet and outlet oil circuit layout, which is not conducive to the design and integration of multi-stage pumps. Generally, the number of stages of the pump is less than 4. On the other hand, like conventional external meshing involute gear pumps, it is limited by filling efficiency and generally has a low speed, usually not higher than 4000 rpm, which is not conducive to the design of high-speed lubricating oil pumps. Summary of the Invention

[0008] The technical problem to be solved by the present invention is to provide a composite structure gear pump, which improves the operating speed range of the external meshing involute gear pump and shortens the axial length of the internal meshing cycloid gear pump to meet the design requirements of high-speed and large-flow lubricating oil pumps.

[0009] Technical solution: To achieve the above purpose, the present invention adopts the following technical solution:

[0010] A composite gear pump includes a pair of external meshing involute gear pumps and several pairs of internal meshing cycloid gear pumps. The external meshing involute gear pumps include a driving gear, a driven gear, a driving gear shaft, and a driven gear shaft. The driving gear shaft and the driven gear shaft are mounted on a lubricating oil pump mounting base, the driving gear is mounted on the driving gear shaft, and the driven gear is mounted on the driven gear shaft.

[0011] During operation, the driving gear shaft drives the driving gear and several pairs of internal meshing cycloid gear pumps installed thereon to rotate in phase, the driving gear drives the driven gear to rotate in the opposite direction, the driven gear drives the driven gear shaft to rotate in phase, and the driven gear shaft drives several pairs of internal meshing cycloid gear pumps installed thereon to rotate in phase.

[0012] Compared with the traditional external gear pump, the external involute gear pump in the above scheme draws on the structural characteristics of the internal cycloid gear pump and sets an axial oil inlet groove on the inlet side, which expands the oil inlet area of ​​the external gear pump and prolongs the oil inlet time of the external gear pump, thereby improving its high-speed performance.

[0013] Furthermore, the external meshing involute gear pump may be provided with an axial oil inlet groove on the inlet side to improve the high speed performance of the external meshing involute gear pump.

[0014] Furthermore, the driving gear and the driven gear in the external meshing involute gear pump can be designed as a single-stage gear pump or as a simple transmission stage.

[0015] Furthermore, the number of teeth of the driving gear and the driven gear may be the same or different.

[0016] Furthermore, the driving gear and the driving gear shaft, the driven gear and the driven gear shaft may be of an integrated design or of a split design.

[0017] Furthermore, the number of rotor pairs of the multiple pairs of internal meshing cycloid gear pumps installed on the driving gear shaft and the number of rotor pairs of the multiple pairs of internal meshing cycloid gear pumps installed on the driven gear shaft may be the same or different.

[0018] Furthermore, the external meshing involute gear pump and the internal meshing cycloid gear pump can be of an integrated design or a split design.

[0019] Furthermore, the driving gear shaft and the driven gear shaft may be solid shafts or hollow shafts.

[0020] Advantages and beneficial technical effects of the present invention:

[0021] 1) The external meshing involute gear pump is provided with an axial oil inlet groove on the inlet side, which can increase the oil inlet area of ​​the gear pump, prolong the oil inlet time, and thus improve the filling efficiency of the lubricating oil on the oil inlet side, and expand the operating speed range of the aviation gear pump; 2) The traditional single-string structure of the internal meshing cycloid gear pump is divided into two strings, which shortens the axial length of the traditional internal meshing cycloid gear pump by about half, saves the installation space of the product, improves the processing technology of the parts, reduces the cantilever torque of the product installation, and improves the structural strength of the product; 3) After being divided into two strings, by adjusting the number of teeth of the driving gear 1 and the driven gear 2, it is possible to achieve the same speed, as well as speed increase or speed decrease, thereby expanding the range of design options. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a schematic diagram of the structure of a traditional positive displacement lubricating oil pump;

[0023] Among them, 1 is the driving gear, 2 is the driven gear, 3 is the housing, 4 is the lubricating oil inlet, and 5 is the lubricating oil outlet.

[0024] Figure 2 This is a schematic diagram of the structure of a traditional internal meshing cycloid gear pump;

[0025] Among them, 1 is the driving gear (inner rotor), O1 is the driving gear's rotation center, 2 is the driven gear (outer rotor), O2 is the driven gear's rotation center, 6 is the lubricating oil inlet side, and 7 is the lubricating oil outlet side;

[0026] Figure 3 This is a schematic structural diagram of the composite gear pump of the present invention;

[0027] Among them, 1 is the driving gear, 2 is the driven gear, 8 is the driving gear shaft, 9 is the driven gear shaft, 10 is the internal meshing cycloid gear pump installed on the driving gear shaft, 11 is the internal meshing cycloid gear pump installed on the driven gear shaft, and 12 is the lubricating oil pump mounting base. DETAILED DESCRIPTION

[0028] The present invention is described in detail below with reference to the accompanying drawings and specific implementation examples. The present invention designs a composite gear pump comprising a pair of external meshing involute gear pumps and a plurality of internal meshing cycloid gear pumps. Figure 38 is the driving gear shaft, 1 is the driving gear, 2 is the driven gear, 9 is the driven gear shaft, 10 is several pairs of internal meshing cycloid gear pumps mounted on the driving gear shaft 8, 11 is several pairs of internal meshing cycloid gear pumps mounted on the driven gear shaft 9, and 12 is the lubricating oil pump mounting base. This composite gear pump improves the operating speed range of external meshing involute gear pumps and shortens the axial length of internal meshing cycloid gear pumps, making it possible to design high-speed, high-flow lubricating oil pumps.

[0029] During operation, the driving gear shaft 8 drives the driving gear 1 and several pairs of internal meshing cycloid gear pumps 10 installed thereon to rotate in phase, the driving gear 1 drives the driven gear 2 to rotate in the opposite direction, the driven gear 2 drives the driven gear shaft 9 to rotate in phase, and the driven gear shaft 9 drives several pairs of internal meshing cycloid gear pumps 11 installed thereon to rotate in phase.

[0030] The external involute gear pump stage has an axial oil inlet groove on the inlet side, which can improve the high-speed performance of the external involute gear pump and increase its operating speed. Dividing the traditional single-string internal cycloid gear pump into two strings shortens the axial length of the traditional internal cycloid gear pump by about half, saving the product's installation space. It also improves the part processing processability, reduces the cantilever torque of the product installation, and improves the product's structural strength. After being divided into two strings, by adjusting the number of teeth of the driving gear 1 and the driven gear 2, it is possible to achieve the same speed or increase or decrease the speed. According to the different speeds of the two shafts, internal cycloid gear pump stages with different structural parameters suitable for the speed can be installed on them, expanding the range of design options.

[0031] Another embodiment of the present invention is described below with reference to the accompanying drawings.

[0032] The structure of this composite gear pump is as follows Figure 3 As shown, during operation, the driving gear shaft 8 drives the driving gear 1 and several pairs of internal meshing cycloid gear pumps 10 installed thereon to rotate in phase, the driving gear 1 drives the driven gear 2 to rotate in the opposite direction, the driven gear 2 drives the driven gear shaft 9 to rotate in phase, and the driven gear shaft 9 drives several pairs of internal meshing cycloid gear pumps 11 installed thereon to rotate in phase.

[0033] Because the gear ratio of driving gear 1 to driven gear 2 is 14:17, a reduction gear transmission is achieved. Therefore, the speed of driven gear shaft 9 is 17.6% lower than that of driving gear shaft 8. Therefore, compared with the internal cycloid gear pump stage 10 mounted on driving gear shaft 8, the internal cycloid gear pump stage 11 mounted on driven gear shaft 9 can be designed with a larger eccentricity structure, which can improve the flow performance of this pump stage. This achieves the design of a high-flow, high-speed lubricating oil pump within a limited space.

[0034] The above specific implementation methods or cases are only used to explain the technical solutions of the present invention and are not intended to limit the present application. Any parts not described in detail are regarded as conventional technical means or common knowledge in the field. Those skilled in the art should understand that based on the design concept of the present application, the technical solutions described in the aforementioned implementation methods can be adaptively modified, or some or all of the technical features therein can be replaced by equivalents. These modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A composite gear pump, characterized in that: It includes a pair of external meshing involute gear pumps and several pairs of internal meshing cycloid gear pumps. The external meshing involute gear pumps include a driving gear, a driven gear, a driving gear shaft, and a driven gear shaft. The driving gear shaft and the driven gear shaft are installed on the lubricating oil pump mounting seat, the driving gear is installed on the driving gear shaft, and the driven gear is installed on the driven gear shaft. During operation, the driving gear shaft drives the driving gear and several pairs of internal meshing cycloid gear pumps installed thereon to rotate in phase, the driving gear drives the driven gear to rotate in the opposite direction, the driven gear drives the driven gear shaft to rotate in phase, and the driven gear shaft drives several pairs of internal meshing cycloid gear pumps installed thereon to rotate in phase; the external meshing involute gear pump is provided with an axial oil inlet groove on the inlet side.

2. The composite gear pump according to claim 1, wherein: The driving gear and the driven gear in the external involute gear pump are designed as a single-stage gear pump or a simple transmission stage.

3. The composite structure gear pump according to claim 2, characterized in that: The driving gear and the driven gear have different numbers of teeth.

4. The composite gear pump according to claim 3, wherein: The gear ratio of the driving gear and the driven gear is 14:

17.

5. The composite structure gear pump according to claim 1, characterized in that: The driving gear and the driving gear shaft, the driven gear and the driven gear shaft are designed as an integrated whole.

6. The composite structure gear pump according to claim 1, characterized in that: The number of rotor pairs of the plurality of pairs of internal meshing cycloid gear pumps installed on the driving gear shaft and the number of rotor pairs of the plurality of pairs of internal meshing cycloid gear pumps installed on the driven gear shaft are different.

7. The composite structure gear pump according to claim 1, characterized in that: The external meshing involute gear pump and the internal meshing cycloid gear pump adopt a split design.

8. The composite structure gear pump according to claim 1, characterized in that: The driving gear shaft and the driven gear shaft are hollow shafts.

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