Variable-displacement multi-stage gear pump

Abstract

The embodiment of the invention discloses a variable displacement multistage gear pump which comprises a driving gear assembly, a driven gear assembly and a transmission shaft, wherein the driving gear assembly and the driven gear assembly are arranged in a gear pump shell and are meshed with each other, and the transmission shaft is arranged in the driving gear assembly in a sleeved mode. The driving gear assembly and the driven gear assembly are arranged to be of a multi-stage gear structure with the same stage number. The driving gear assembly at least comprises a first-stage driving gear and a second-stage driving gear which are sequentially arranged on the transmission shaft in a sleeving mode. The driven gear assembly at least comprises a first-stage driven gear used for being meshed with the first-stage driving gear and a second-stage driven gear used for being meshed with the second-stage driving gear. At least a first-stage external spline and a second-stage external spline are arranged outside a shaft body of the transmission shaft, a first-stage driving gear arranged on the transmission shaft in a sleeving mode is always in a meshed state with the first-stage external spline on the transmission shaft through an internal spline of the first-stage driving gear, and therefore the first-stage driving gear and a first-stage driven gear are driven to work through rotation of the transmission shaft. The minimum flow required by the gear pump is guaranteed; the transmission shaft moves in the axial direction of the transmission shaft, so that the second-stage external spline on the transmission shaft is engaged with the second-stage driving gear, and the second-stage driving gear and the second-stage driven gear are driven to synchronously work with the first-stage driving gear and the first-stage driven gear through rotation of the transmission shaft. According to the technical scheme, the problems that a large amount of power is consumed, the temperature rise of components is increased, the service life is shortened and the like due to non-adjustable displacement of an existing gear pump are solved.

Description

Technical Field

[0001] The present invention relates to the field of gear pump technology, but is not limited to it, and in particular to a variable displacement multi-stage gear pump. Background Art

[0002] Gear pumps are widely used in engineering fields due to their simple structure, high reliability and strong anti-pollution ability. As a positive displacement pump, the flow rate of a gear pump is proportional to the width of the gear. During operation, the product displacement is often much greater than the actual demand, resulting in a large amount of power loss, a large temperature rise of the fluid, and a shortened service life of components.

[0003] Currently, the gear pumps on the market are generally fixed displacement pumps, that is, the displacement at the pump outlet is constant for a given speed and pressure difference, but the actual demand is often far less than the actual displacement of the pump, resulting in a large amount of power loss, increased temperature rise of components and shortened life. Summary of the invention

[0004] Purpose of the present invention: In order to solve the above technical problems, the embodiment of the present invention provides a variable displacement multi-stage gear pump to solve the problems of existing gear pumps due to the non-adjustable displacement, resulting in large power loss, increased temperature rise of components and shortened life.

[0005] Technical solution of the present invention: The embodiment of the present invention provides a variable displacement multi-stage gear pump, comprising: a gear pump housing 5, a driving gear assembly and a driven gear assembly meshing with each other arranged in the gear pump housing 5, and a transmission shaft 17 sleeved in the driving gear assembly;

[0006] The driving gear assembly and the driven gear assembly are arranged as a multi-stage gear structure with the same number of stages, and the driving gear assembly and the driven gear assembly include at least two stages of gears meshing with each other; the driving gear assembly includes at least a primary driving gear 2 and a secondary driving gear 3 sequentially sleeved on the transmission shaft 17; the driven gear assembly includes at least: a primary driven gear 6 for meshing with the primary driving gear 2, and a secondary driven gear 7 for meshing with the secondary driving gear 3;

[0007] At least one primary external spline and a secondary external spline are arranged on the outside of the shaft body of the transmission shaft 17. The primary driving gear 2 sleeved on the transmission shaft 17 is always in meshing state with the primary external spline on the transmission shaft 17 through its internal spline, so that the primary driving gear 2 and the primary driven gear 6 are driven to work through the rotation of the transmission shaft 17, so as to ensure the minimum flow required by the gear pump; through the movement of the transmission shaft 17 along its axial direction, the secondary external spline on the transmission shaft 17 is in meshing state with the secondary driving gear 3, so that the secondary driving gear 3 and the secondary driven gear 7 are driven to work synchronously with the primary driving gear 2 and the primary driven gear 6 through the rotation of the transmission shaft 17.

[0008] Optionally, in the variable displacement multi-stage gear pump as described above,

[0009] The first-stage driving gear 2 is configured as an annular cylindrical structure with internal splines, and the outer ring of the annular boss arranged on the outer cylindrical surface thereof forms external meshing teeth for meshing and rotating with the first-stage driven gear 6; the gear ruler width of the first-stage driving gear 2 is determined by the small flow condition of the gear pump.

[0010] Optionally, the variable displacement multi-stage gear pump as described above further includes: a secondary positioning assembly for synchronizing the speed of the secondary driving gear 3 with the transmission shaft 17; the secondary positioning assembly includes: a secondary positioning ring 9, a secondary corrugated gasket 10, a secondary slider 11, and a secondary synchronization ring 12;

[0011] The secondary driving gear 3 is configured as a ring-shaped columnar structure as a whole, and the middle part of the inner column wall thereof has an internal spline, and the end of the internal spline close to the primary driving gear 2 is provided with a conical front end, and the rear end of the internal spline has a friction inner cone cavity and a positioning ring groove, and the outer ring of the annular shoulder provided on the outer cylindrical surface thereof is formed with external meshing teeth for meshing and rotating with the secondary driven gear 7; and the width of the secondary driving gear 3 is determined by the medium flow condition and the width of the primary driving gear 2;

[0012] The secondary synchronizer ring 12 is configured as an annular structure with a conical surface, and a plurality of slider grooves are provided on the inner cylindrical surface thereof in the circumferential direction, for placing a secondary corrugated gasket 10 and a secondary slider 11 in each slider groove, and the secondary synchronizer ring 12 with the secondary corrugated gasket 10 and the secondary slider 11 is integrally installed in the friction inner cone cavity of the secondary driving gear 3, and the secondary positioning ring 9 is installed in the positioning ring groove, for limiting the axial installation position of the secondary synchronizer ring 12; the conical end of the secondary synchronizer ring 12 is provided with an internal spline and a conical front end;

[0013] The secondary slider 11 has a conical ramp, which cooperates with the secondary spline on the transmission shaft 17 through its conical ramp. The rotation of the transmission shaft 17 drives the secondary slider 11 and the secondary synchronizer ring 12 to rotate, and the secondary slide on the secondary spline is used to limit the axial position of the secondary spline in the transmission shaft 17.

[0014] Optionally, in the variable displacement multi-stage gear pump as described above, the transmission shaft 17 includes: a shaft body, a primary external spline, a secondary external spline, and a secondary transition section arranged in sequence from the input end of the shaft body; wherein the diameter of the secondary transition section is smaller than the minor diameter of the internal spline of the gear, the secondary external spline is provided with a plurality of secondary ramps along the circumferential direction, and the secondary transition section is provided with a secondary sliding groove starting from the position of the secondary ramp, which is used to avoid the secondary slider 11 during installation; the plurality of secondary ramps are used to limit the plurality of secondary sliders 11 in a one-to-one correspondence.

[0015] Optionally, in the variable displacement multi-stage gear pump as described above,

[0016] The variable displacement multi-stage gear pump is used to drive the secondary slider 11 and the secondary synchronizer ring 12 to make synchronous axial movement during the axial movement of the transmission shaft 17 toward the secondary driving gear 3, until the conical end surface of the secondary synchronizer ring 12 abuts against the end of the friction inner conical surface of the secondary driving gear 3, and the friction force generated by the two friction surfaces drives the secondary driving gear 3 to rotate, until the rotation speed of the secondary driving gear 3 is the same as that of the transmission shaft 17, the dynamic friction is converted into static friction, and the secondary ramp on the transmission shaft 17 pushes the secondary slider 11 to overcome the elastic force of the secondary corrugated gasket 10 and then move radially, so that the transmission shaft 17 continues to move axially toward the secondary driving gear 3, until the secondary external spline is meshed with the internal spline of the secondary driving gear 3 and the internal spline of the secondary synchronizer ring 12, driving the secondary driving gear 3 to rotate synchronously.

[0017] Optionally, in the variable displacement multi-stage gear pump as described above, the driving gear assembly further includes: a three-stage driving gear 4 sleeved on the transmission shaft 17, and the driven gear assembly further includes: a three-stage driven gear 8 for meshing with the three-stage driving gear 4; the shaft body of the transmission shaft 17 is also provided with a three-stage external spline;

[0018] By moving the transmission shaft 17 along its axial direction, the third-stage external spline on the transmission shaft 17 is in meshing state with the internal spline of the third-stage driving gear 4, so that the third-stage driving gear 4 and the third-stage driven gear 8, the second-stage driving gear 3 and the second-stage driven gear 7, and the first-stage driving gear 2 and the first-stage driven gear 6 are driven to work synchronously through the rotation of the transmission shaft 17.

[0019] Optionally, the variable displacement multi-stage gear pump as described above further comprises: a three-stage positioning assembly for synchronizing the speed of the three-stage driving gear 4 with the transmission shaft 17; the three-stage positioning assembly comprises: a three-stage positioning ring 13, a three-stage corrugated gasket 14, a three-stage slider 15, and a three-stage synchronization ring 16;

[0020] The three-stage driving gear 4 is configured as a ring-shaped columnar structure as a whole, and the middle part of the inner column wall thereof has an internal spline, and the end of the internal spline close to the second-stage driving gear 3 is provided with a conical front end, and the rear end of the internal spline has a friction inner cone cavity and a positioning ring groove, and the outer ring of the annular shoulder provided on the outer cylindrical surface thereof is formed with external meshing teeth for meshing and rotating with the three-stage driven gear 8; and the width of the three-stage driving gear 3 is determined by the rated flow of the product and the width of the first-stage driving gear 2 and the second-stage driving gear 3;

[0021] The three-stage synchronizer ring 16 is configured as a ring structure with a conical surface, and a plurality of slider grooves are provided on the inner cylindrical surface thereof along the circumferential direction, for placing a three-stage corrugated gasket 14 and a three-stage slider 15 in each slider groove, and the three-stage synchronizer ring 16 with the three-stage corrugated gasket 14 and the three-stage slider 15 is integrally installed in the friction inner cone cavity of the three-stage driving gear 4, and the three-stage positioning ring 13 is installed in the positioning ring groove, for limiting the axial installation position of the three-stage synchronizer ring 16; the conical end of the three-stage synchronizer ring 16 is provided with an inner spline and a conical front end;

[0022] The three-stage slider 15 has a conical inclined platform, which cooperates with the three-stage spline on the transmission shaft 17 through its conical inclined platform. The rotation of the transmission shaft 17 drives the three-stage slider 15 and the three-stage synchronous ring 16 to rotate, and the three-stage slider on the three-stage spline is used to limit the axial position of the three-stage spline in the transmission shaft 17.

[0023] Optionally, in the variable displacement multi-stage gear pump as described above,

[0024] The transmission shaft 17 also includes: a three-level external spline and a three-level transition section from the secondary transition section to the shaft end; wherein the diameter of the three-level transition section is smaller than the minor diameter of the internal spline of the gear, a plurality of three-level slides are circumferentially arranged at the preset position of the three-level external spline, and a three-level sliding groove is arranged at the position of each three-level slide in the three-level transition section for avoiding the three-level slider 15 during installation; the plurality of three-level slides are used for limiting the plurality of three-level sliders 15 in a one-to-one correspondence.

[0025] Optionally, in the variable displacement multi-stage gear pump as described above,

[0026] The variable displacement multi-stage gear pump is used to drive the three-stage slider 15 and the three-stage synchronizer ring 16 to make synchronous axial movement during the axial movement of the transmission shaft 17 toward the three-stage driving gear 4, until the conical end surface of the three-stage synchronizer ring 16 abuts against the end of the friction inner conical surface of the three-stage driving gear 4, and the friction force generated by the two friction surfaces drives the three-stage driving gear 4 to rotate, until the rotation speed of the three-stage driving gear 4 is the same as that of the transmission shaft 17, the dynamic friction is converted into static friction, and the three-stage slide on the transmission shaft 17 pushes the three-stage slider 15 to overcome the elastic force of the three-stage driving gear 4 and then move radially, so that the transmission shaft 17 continues to move axially toward the three-stage driving gear 4, until the three-stage external spline is meshed with the internal spline of the three-stage driving gear 4 and the internal spline of the three-stage synchronizer ring 16, driving the three-stage synchronizer ring 16 and the three-stage driving gear 4 to rotate synchronously.

[0027] Optionally, in the variable displacement multi-stage gear pump as described above,

[0028] The number of teeth of the secondary external spline in the transmission shaft 17 is equal to the number of teeth of the primary external spline minus the number of secondary slides, and the reduced number of spline teeth is used to process the secondary sliding groove in the transmission shaft 17; the front end of the secondary external spline in the transmission shaft 17 has a bevel spline that is the same as the front end of the internal spline of the secondary synchronizer ring 12, which is used for pre-synchronization with the internal spline of the secondary gear; the length of the secondary external spline in the transmission shaft 17 is not less than the sum of the lengths of the internal spline of the secondary driving gear 3 and the internal spline of the tertiary driving gear 4;

[0029] The number of spline teeth of the third-stage external spline in the transmission shaft 17 is equal to the number of teeth of the first-stage external spline minus the number of the third-stage slides, and the reduced number of spline teeth is used to process the third-stage sliding groove in the transmission shaft 17; the front end of the third-stage external spline in the transmission shaft 17 has the same bevel spline as the front end of the internal spline of the third-stage synchronizer ring 16; the length of the third-stage external spline in the transmission shaft 17 is not less than the length of the internal spline of the third-stage driving gear 4.

[0030] Beneficial effects of the present invention: In response to the design requirements of variable displacement gear pumps that are urgently needed in the market, the variable displacement multi-stage gear pump provided in the embodiment of the present invention includes: a gear pump housing 5, a driving gear assembly and a driven gear assembly that are meshed with each other and are arranged in the gear pump housing 5, and a transmission shaft 17 sleeved in the driving gear assembly; the driving gear assembly and the driven gear assembly include at least two stages of gears that are meshed with each other; accordingly, at least a primary external spline and a secondary external spline are arranged on the outside of the shaft body of the transmission shaft 17, and the primary driving gear 2 sleeved on the transmission shaft 17 is always in a meshing state with the primary external spline on the transmission shaft 17 through its internal spline, so that the primary driving gear 2 and the primary driven gear 6 are driven to work through the rotation of the transmission shaft 17, so as to ensure the minimum flow required by the gear pump; through the movement of the transmission shaft 17 along its axial direction, the secondary external spline on the transmission shaft 17 is in a meshing state with the secondary driving gear 3, so that the secondary driving gear 3 and the secondary driven gear 7 are driven to work synchronously with the primary driving gear 2 and the primary driven gear 6 through the rotation of the transmission shaft 17. The variable displacement multistage gear pump provided in the embodiment of the present invention applies an axial force to the transmission shaft 17 to change the position of the transmission shaft 17, change the number of gear stages meshed by the transmission shaft 17, and thus change the displacement requirement of the multistage gear pump. Compared with the existing multistage gear pump structure, the structure of the variable displacement multistage gear pump has a simple control method, greatly reduced volume and weight, and is easier to apply to the engineering field. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The accompanying drawings are used to provide a further understanding of the technical solution of the present invention and constitute a part of the specification. Together with the embodiments of the present application, they are used to explain the technical solution of the present invention and do not constitute a limitation on the technical solution of the present invention.

[0032] Figure 1 A schematic diagram of the overall structure of a variable displacement multi-stage gear pump provided by an embodiment of the present invention;

[0033] Figure 2 for Figure 1 The illustrated embodiment provides a partially enlarged structural schematic diagram of a driving gear assembly and a driven gear assembly in a variable displacement multi-stage gear pump;

[0034] Figure 3 The schematic diagram of the structure of each driving gear in the variable displacement multi-stage gear pump provided by the embodiment of the present invention is as follows: Figure 3 Figure a is an overall cross-sectional view, and Figure b is a partial enlarged schematic diagram of the internal spline position;

[0035] Figure 4 A schematic structural diagram of a secondary speed synchronization component in a variable displacement multi-stage gear pump provided by an embodiment of the present invention;

[0036] Figure 5 for Figure 4 A schematic diagram of the structure of a secondary slider in a secondary speed synchronization assembly provided by the illustrated embodiment;

[0037] Figure 6 for Figure 4 A schematic structural diagram of a secondary synchronization ring in a secondary speed synchronization assembly provided by the illustrated embodiment;

[0038] Figure 7 A schematic diagram of the structure of a transmission shaft in a variable displacement multi-stage gear pump provided by an embodiment of the present invention, Figure 7 Figure a is a schematic diagram of the overall structure of the transmission shaft, and Figure b is a partial enlarged schematic diagram of the ramp position;

[0039] Figure 8 A schematic diagram of an application of a variable displacement multi-stage gear pump provided in an embodiment of the present invention in a power input device.

[0040] Description of reference numerals:

[0041] 1-sliding bearing; 2-first-stage driving gear; 3-second-stage driving gear; 4-third-stage driving gear; 5-gear pump housing; 6-first-stage driven gear; 7-second-stage driven gear; 8-third-stage driven gear; 9-second-stage positioning ring; 10-second-stage corrugated gasket; 11-second-stage slider; 12-second-stage synchronizing ring; 13-third-stage positioning ring; 14-third-stage corrugated gasket; 15-third-stage slider; 16-third-stage synchronizing ring; 17-transmission shaft. DETAILED DESCRIPTION

[0042] In order to make the purpose, technical solution and advantages of the present invention more clear, the embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that the embodiments and features in the embodiments of the present application can be combined with each other arbitrarily without conflict.

[0043] The above background technology has explained the influence of the gear width in the gear pump on its displacement, and that the conventional gear pump is a fixed displacement pump. Since the displacement of the gear pump is not adjustable, it leads to a large amount of power loss, increased temperature rise of components and shortened life.

[0044] Europe, the United States and other countries have successively published relevant literature on the research of multi-stage gear pumps. The principle is that all meshing gears in the multi-stage gear pump rotate synchronously during operation, and a unique regulator is designed to control the outlet pressure of each stage of the gear pump to achieve the displacement under the required pressure. This type of structure is more complicated to adjust, and the design of a unique regulator increases the volume and weight of the product, so this type of structure is difficult to put into practical engineering applications. Therefore, the market urgently needs a variable displacement gear pump with advantages such as simple structure, small volume and light weight.

[0045] In response to the above problems and the demand for gear pumps, an embodiment of the present invention provides a variable displacement multi-stage gear pump, which can control the displacement of the gear pump at a certain speed by controlling the position of the gear pump drive shaft.

[0046] The present invention provides the following specific embodiments which can be combined with each other. The same or similar concepts or processes may not be described in detail in some embodiments.

[0047] Figure 1 The overall structural diagram of the variable displacement multi-stage gear pump provided by the embodiment of the present invention is as follows: Figure 2 for Figure 1 The embodiment shown is a partial enlarged structural diagram of the driving gear assembly and the driven gear assembly in the variable displacement multi-stage gear pump. Figure 1 and Figure 2 As shown, the main structure of the variable displacement multi-stage gear pump provided by the embodiment of the present invention may include: a gear pump housing 5, a driving gear assembly and a driven gear assembly that are arranged in the gear pump housing 5 and mesh with each other, and a transmission shaft 17 that is sleeved in the driving gear assembly.

[0048] In an embodiment of the present invention, the driving gear assembly and the driven gear assembly are configured as a multi-stage gear structure with the same number of stages (for example, a two-stage gear structure, or a three-stage or four-stage gear structure), and the driving gear assembly and the driven gear assembly include at least two stages of gears meshing with each other.

[0049] The driving gear assembly in the embodiment of the present invention includes at least a primary driving gear 2 and a secondary driving gear 3 which are sequentially sleeved on the transmission shaft 17; correspondingly, the driven gear assembly includes at least a primary driven gear 6 for meshing with the primary driving gear 2, and a secondary driven gear 7 for meshing with the secondary driving gear 3.

[0050] Corresponding to the above-mentioned structure with at least two-stage gears, at least one primary external spline and a secondary external spline are arranged on the outside of the shaft body of the transmission shaft 17 in the embodiment of the present invention. The primary driving gear 2 sleeved on the transmission shaft 17 is always in meshing state with the primary external spline on the transmission shaft 17 through its internal spline, so that the primary driving gear 2 and the primary driven gear 6 are driven to work through the rotation of the transmission shaft 17 to ensure the minimum flow required by the gear pump; the secondary external spline on the transmission shaft 17 is in meshing state with the secondary driving gear 3 through the movement of the transmission shaft 17 along its axial direction, so that the secondary driving gear 3 and the secondary driven gear 7 are driven to work synchronously with the primary driving gear 2 and the primary driven gear 6 through the rotation of the transmission shaft 17.

[0051] In an implementation of the embodiment of the present invention, a structural form of a first-stage driving gear 2 is provided.

[0052] The first-stage driving gear 2 in this implementation is configured as an annular cylindrical structure with internal splines, and the outer ring of the annular boss arranged on the outer cylindrical surface thereof forms external meshing teeth for meshing and rotating with the first-stage driven gear 6; the gear ruler width of the first-stage driving gear 2 is determined by the small flow condition of the gear pump.

[0053] In the specific implementation of the embodiment of the present invention, the variable displacement multi-stage gear pump also includes: a secondary positioning component for synchronizing the speed of the secondary driving gear 3 with the transmission shaft 17; the secondary positioning component includes: a secondary positioning ring 9, a secondary corrugated gasket 10, a secondary slider 11, and a secondary synchronization ring 12. Figure 3 The schematic diagram of the structure of each driving gear in the variable displacement multi-stage gear pump provided by the embodiment of the present invention is as follows: Figure 3 Figure a is an overall cross-sectional view, and Figure b is a partial enlarged schematic diagram of the internal spline position; Figure 4 A schematic structural diagram of a secondary speed synchronization component in a variable displacement multi-stage gear pump provided by an embodiment of the present invention; Figure 5 for Figure 4 The schematic diagram of the structure of the secondary slider in the secondary speed synchronization assembly provided by the embodiment shown, Figure 6 for Figure 4 The illustrated embodiment provides a schematic structural diagram of a secondary synchronization ring in a secondary speed synchronization assembly.

[0054] like Figure 3 As shown, the secondary driving gear 3 in the embodiment of the present invention is configured as a ring-shaped columnar structure as a whole, the middle part of the inner column wall of which has an internal spline, the end of the internal spline close to the primary driving gear 2 is provided with a conical front end, the rear end of the internal spline has a friction inner cone cavity and a positioning ring groove, the outer ring of the annular boss arranged on the outer cylindrical surface thereof is formed with external meshing teeth for meshing and rotating with the secondary driven gear 7; and the width of the secondary driving gear 3 is determined by the medium flow condition and the width of the primary driving gear 2.

[0055] like Figure 6 As shown, the secondary synchronizer ring 12 in the embodiment of the present invention is configured as an annular structure with a conical surface, and a plurality of slider grooves are opened on the inner cylindrical surface thereof in the circumferential direction, for placing a secondary corrugated gasket 10 and a secondary slider 11 in each slider groove, and the secondary synchronizer ring 12 with the secondary corrugated gasket 10 and the secondary slider 11 is integrally installed in the friction inner cone cavity of the secondary driving gear 3, and the secondary positioning ring 9 is installed in the positioning ring groove, for limiting the axial installation position of the secondary synchronizer ring 12; the conical end of the secondary synchronizer ring 12 is provided with an inner spline and a conical front end.

[0056] like Figure 5 As shown, the secondary slider 11 in the embodiment of the present invention has a conical inclined platform, which cooperates with the secondary spline on the transmission shaft 17 through its conical inclined platform. The rotation of the transmission shaft 17 drives the secondary slider 11 and the secondary synchronizer ring 12 to rotate, and the secondary slide on the secondary spline is used to limit the axial position of the secondary spline in the transmission shaft 17.

[0057] In one implementation of the embodiment of the present invention, an implementation structure of the transmission shaft 17 is provided. Figure 7 A schematic diagram of the structure of a transmission shaft in a variable displacement multi-stage gear pump provided by an embodiment of the present invention, Figure 7 Figure a is a schematic diagram of the overall structure of the transmission shaft, and figure b is a locally enlarged schematic diagram of the ramp position.

[0058] The transmission shaft 17 in this implementation includes: a shaft body, a primary external spline, a secondary external spline, and a secondary transition section arranged in sequence from the input end of the shaft body; wherein the diameter of the secondary transition section is smaller than the minor diameter of the internal spline of the gear, the secondary external spline is provided with a plurality of secondary ramps along the circumferential direction, the secondary transition section is provided with a secondary sliding groove starting from the position of the secondary ramp, for avoiding the secondary slider 11 during installation; the plurality of secondary ramps are used for limiting the plurality of secondary sliders 11 in a one-to-one correspondence.

[0059] The above embodiment of the present invention is described by taking a two-stage gear pump as an example. The working principle of the variable displacement multi-stage gear pump (i.e. the above-mentioned two-stage gear pump) is as follows:

[0060] During the axial movement of the transmission shaft 17 toward the secondary driving gear 3, the secondary slider 11 and the secondary synchronizer ring 12 are driven to make synchronous axial movement until the conical end face of the secondary synchronizer ring 12 abuts against the end of the friction inner conical face of the secondary driving gear 3. The friction force generated by the two friction faces drives the secondary driving gear 3 to rotate until the rotation speed of the secondary driving gear 3 is the same as that of the transmission shaft 17. The dynamic friction is converted into static friction. The secondary ramp on the transmission shaft 17 pushes the secondary slider 11 to overcome the elastic force of the secondary corrugated gasket 10 and then move radially, so that the transmission shaft 17 continues to move axially toward the secondary driving gear 3 until the secondary external spline is meshed with the internal spline of the secondary driving gear 3 and the internal spline of the secondary synchronizer ring 12, driving the secondary driving gear 3 to rotate synchronously.

[0061] Further, in an implementation of the embodiment of the present invention, based on the structure of the two-stage gear pump provided in the above embodiment, a three-stage gear pump can be formed. Figure 1 and Figure 2 As shown, the driving gear assembly also includes: a three-stage driving gear 4 sleeved on the transmission shaft 17; the matched driven gear assembly also includes: a three-stage driven gear 8 for meshing with the three-stage driving gear 4; the shaft body of the transmission shaft 17 is also provided with a three-stage external spline, such as Figure 7 shown.

[0062] In this implementation, the transmission shaft 17 is moved along its axial direction so that the third-stage external spline on the transmission shaft 17 is in meshing state with the internal spline of the third-stage driving gear 4, thereby driving the third-stage driving gear 4 and the third-stage driven gear 8, the second-stage driving gear 3 and the second-stage driven gear 7, and the first-stage driving gear 2 and the first-stage driven gear 6 to work synchronously through the rotation of the transmission shaft 17.

[0063] The three-stage gear pump proposed in this implementation also includes: a three-stage positioning assembly for the three-stage driving gear 4 and the transmission shaft 17; the three-stage positioning assembly includes: a three-stage positioning ring 13, a three-stage corrugated gasket 14, a three-stage slider 15, and a three-stage synchronization ring 16; the three-stage positioning assembly and the structure of each component therein refer to Figures 4 to 6 shown.

[0064] refer to Figure 3 As shown, the structure of the tertiary driving gear 4 is the same as that of the secondary driving gear 3, that is, the tertiary driving gear 4 is arranged as a ring-shaped columnar structure as a whole, the middle part of the inner column wall thereof has an internal spline, the end of the internal spline close to the secondary driving gear 3 is provided with a conical front end, the rear end of the internal spline has a friction inner cone cavity and a positioning ring groove, the outer ring of the annular boss arranged on the outer cylindrical surface thereof is formed with external meshing teeth for meshing and rotating with the tertiary driven gear 8; and the width of the tertiary driving gear 3 is determined by the rated flow of the product and the widths of the primary driving gear 2 and the secondary driving gear 3.

[0065] Reference Figures 4 to 6 Similar to the secondary positioning assembly, in the tertiary positioning assembly, the tertiary synchronization ring 16 is configured as an annular structure with a conical surface, and a plurality of slider grooves are provided on the inner cylindrical surface thereof in the circumferential direction, for placing a tertiary corrugated gasket 14 and a tertiary slider 15 in each slider groove, and the tertiary synchronization ring 16 with the tertiary corrugated gasket 14 and the tertiary slider 15 is integrally installed in the friction inner cone cavity of the tertiary driving gear 4, and the tertiary positioning ring 13 is installed in the positioning ring groove, for limiting the axial installation position of the tertiary synchronization ring 16; the conical end of the tertiary synchronization ring 16 is provided with an inner spline and a conical front end.

[0066] The three-stage slider 15 has a conical inclined platform, which cooperates with the three-stage spline on the transmission shaft 17 through its conical inclined platform. The rotation of the transmission shaft 17 drives the three-stage slider 15 and the three-stage synchronous ring 16 to rotate, and the three-stage slider on the three-stage spline is used to limit the axial position of the three-stage spline in the transmission shaft 17.

[0067] For the above three-stage gear pump structure, Figure 7 As shown, the transmission shaft 17 also includes: a three-stage external spline and a three-stage transition section from the secondary transition section to the shaft end; wherein, the diameter of the three-stage transition section is smaller than the minor diameter of the internal spline of the gear, a plurality of three-stage slides are circumferentially arranged at the preset position of the three-stage external spline, and a three-stage sliding groove is arranged at the position of each three-stage slide in the three-stage transition section for avoiding the three-stage slider 15 during installation; the plurality of three-stage slides are used for limiting the plurality of three-stage sliders 15 in a one-to-one correspondence.

[0068] The above embodiment of the present invention is described by taking a three-stage gear pump as an example. The working principle of the variable displacement multi-stage gear pump (i.e. the above three-stage gear pump) is as follows:

[0069] The variable displacement multi-stage gear pump is used to drive the three-stage slider 15 and the three-stage synchronizer ring 16 to make synchronous axial movement during the axial movement of the transmission shaft 17 toward the three-stage driving gear 4, until the conical end face of the three-stage synchronizer ring 16 abuts against the end of the friction inner conical surface of the three-stage driving gear 4, and the friction force generated by the two friction surfaces drives the three-stage driving gear 4 to rotate, until the rotation speed of the three-stage driving gear 4 is the same as that of the transmission shaft 17, the dynamic friction is converted into static friction, and the three-stage slide on the transmission shaft 17 pushes the three-stage slider 15 to overcome the elastic force of the three-stage driving gear 4 and then move radially, so that the transmission shaft 17 continues to move axially toward the three-stage driving gear 4, until the three-stage external spline is meshed with the internal spline of the three-stage driving gear 4 and the internal spline of the three-stage synchronizer ring 16, driving the three-stage synchronizer ring 16 and the three-stage driving gear 4 to rotate synchronously.

[0070] It should be noted that the number of spline teeth of the secondary external spline in the transmission shaft 17 of the embodiment of the present invention is equal to the number of teeth of the primary external spline minus the number of secondary slides (i.e., secondary sliders), and the reduced number of spline teeth is used to process the secondary sliding groove in the transmission shaft 17; the front end of the secondary external spline in the transmission shaft 17 has a bevel spline that is the same as the front end of the internal spline of the secondary synchronizer ring 12, which is used for pre-synchronization with the internal spline of the secondary gear; the length of the secondary external spline in the transmission shaft 17 is not less than the sum of the lengths of the internal spline of the secondary driving gear 3 and the internal spline of the tertiary driving gear 4.

[0071] Similarly, the number of spline teeth of the third-stage external spline in the transmission shaft 17 is equal to the number of teeth of the first-stage external spline minus the number of the third-stage slide (i.e., the third-stage slider), and the reduced number of spline teeth is used to process the third-stage sliding groove in the transmission shaft 17; the front end of the third-stage external spline in the transmission shaft 17 has the same bevel spline as the front end of the internal spline of the third-stage synchronizer ring 16; the length of the third-stage external spline in the transmission shaft 17 is not less than the length of the internal spline of the third-stage driving gear 4.

[0072] In response to the design requirements of the variable displacement gear pump urgently needed by the market, the variable displacement multi-stage gear pump provided in the embodiment of the present invention includes: a gear pump housing 5, a driving gear assembly and a driven gear assembly meshing with each other arranged in the gear pump housing 5, and a transmission shaft 17 sleeved in the driving gear assembly; the driving gear assembly and the driven gear assembly include at least two stages of gears meshing with each other; accordingly, the shaft body of the transmission shaft 17 is provided with at least a primary external spline and a secondary external spline on the outside, and the primary driving gear 2 sleeved on the transmission shaft 17 is always in meshing state with the primary external spline on the transmission shaft 17 through its internal spline, so that the primary driving gear 2 and the primary driven gear 6 are driven to work through the rotation of the transmission shaft 17, so as to ensure the minimum flow required by the gear pump; through the movement of the transmission shaft 17 along its axial direction, the secondary external spline on the transmission shaft 17 is in meshing state with the secondary driving gear 3, so that the secondary driving gear 3 and the secondary driven gear 7 are driven to work synchronously with the primary driving gear 2 and the primary driven gear 6 through the rotation of the transmission shaft 17. The variable displacement multistage gear pump provided in the embodiment of the present invention applies an axial force to the transmission shaft 17 to change the position of the transmission shaft 17, change the number of gear stages meshed by the transmission shaft 17, and thus change the displacement requirement of the multistage gear pump. Compared with the existing multistage gear pump structure, the structure of the variable displacement multistage gear pump has a simple control method, greatly reduced volume and weight, and is easier to apply to the engineering field.

[0073] The following is a schematic illustration of the implementation of the variable displacement multi-stage gear pump provided by the embodiment of the present invention through a specific implementation example.

[0074] Implementation Example

[0075] To achieve the purpose of the present invention, this embodiment provides a Figure 1The variable displacement multi-stage gear pump shown in this implementation example is described using a three-stage gear pump as an example.

[0076] See also Figures 1 to 7 As shown, the variable displacement multi-stage gear pump (i.e., variable displacement three-stage gear pump) provided by this implementation example includes: a sliding bearing 1, a primary driving gear 2, a secondary driving gear 3, a third driving gear 4, a gear pump housing 5, a primary driven gear 6, a secondary driven gear 7, a third driven gear 8, a secondary positioning ring 9, a secondary corrugated gasket 10, a secondary slider 11, a secondary synchronizing ring 12, a third synchronizing ring 13, a third corrugated gasket 14, a third slider 15, a third synchronizing ring 16 and a transmission shaft 17.

[0077] In this implementation example, the gear pump housing 5 is used to house the internal components of the gear pump; the sliding bearing 1 is used to support the gear to perform rotational motion.

[0078] The driving gear structure is described as follows: the first-stage driving gear 2 is composed of external meshing teeth, meshing and rotating with the first-stage driven gear 6. The width of the first-stage driving gear 2 is determined by the small flow condition; the first-stage driving gear 2 is composed of internal splines for transmitting power.

[0079] The secondary driving gear 3 mainly includes: external meshing teeth, internal splines, friction inner cone surface, conical front end and positioning ring groove. Figure 3 As shown, the outer meshing teeth of the secondary driving gear 3 are used to mesh and rotate with the secondary driven gear 7. The width of the secondary driving gear 3 is determined by the medium flow condition and the width of the primary driving gear 2. The secondary driving gear 3 is provided with an internal spline for transmitting power. The front end of the internal spline is a conical front end. The enlarged view thereof is shown in FIG. Figure 3 In addition, the friction inner cone surface is located adjacent to the conical front end inside the secondary driving gear 3, and the high friction material is coated at this position; a positioning ring groove is provided inside the secondary driving gear 3 for accommodating the secondary positioning ring 9.

[0080] The third-stage driving gear 4 has the same structure as the second-stage driving gear 3, and is composed of external meshing teeth, internal splines, friction inner cone surface, conical front end and positioning ring groove; the external meshing teeth of the third-stage driving gear 4 mesh with the third-stage driven gear 8 for rotation, and the width of the third-stage driving gear 4 is determined by the rated flow of the product and the width of the first-stage driving gear 2 and the second-stage driving gear 3; the internal spline composition of the third-stage driving gear 4 is used to transmit power, and the front end of the internal spline is a conical front end. In addition, the friction inner cone surface is adjacent to the conical front end inside the third-stage driving gear 4, and this position is coated with high friction material; and a positioning ring groove is provided inside the third-stage driving gear 4 for placing the third-stage positioning ring 13.

[0081] The primary driven gear 6, the secondary driven gear 7 and the tertiary driven gear 8 are respectively meshed with the primary driving gear 2, the secondary driving gear 3 and the tertiary driving gear 4 for use.

[0082] The speed synchronization of the secondary driving gear 3 and the transmission shaft 17 is achieved through the combined structure of the secondary positioning ring 9, the secondary corrugated gasket 10, the secondary slider 11, and the secondary synchronization ring 12. The specific structure is described as follows:

[0083] The secondary positioning ring 9 is configured as a non-full-circular retaining ring. For ease of assembly, tweezer holes are provided at both ends of the retaining ring. The secondary positioning ring 9 should be made of wear-resistant material and its surface processing accuracy requirements should be strictly controlled. The outer cylinder of the secondary positioning ring 9 is precisely assembled with the positioning ring groove in the secondary driving gear 3.

[0084] The secondary corrugated gasket 10 is processed from an elastic rectangular gasket to have a certain value of corrugated elastic force so as to support the secondary slider 11;

[0085] The secondary slider 11 is mainly composed of a slider seat and an inclined platform. Figure 5 As shown, the angle of the inclined surface of the conical ramp in the secondary slider 11 is related to the load of the secondary driving gear 3 and the friction between the secondary synchronizing ring 12 and the inner conical surface of the secondary driving gear 3.

[0086] The secondary synchronizer ring 12 is mainly composed of an outer cone surface, an inner spline, a conical front end and a slider groove, as shown below Figure 6 As shown. The secondary synchronizer ring 12 uses a certain elastic metal material, the angle of the outer cone surface is slightly larger than the angle of the friction cone surface of the secondary driving gear 3, and the outer cone surface has certain textures and is coated with high friction materials. It should be noted that the internal spline tooth profile parameters of the secondary synchronizer ring 12 are consistent with the internal spline tooth profile parameters of the primary driving gear 2, the secondary driving gear 3 and the tertiary driving gear 4, and the front end of the internal spline is a conical front end; in addition, the inner surface of the secondary synchronizer ring 12 is processed with slider grooves for accommodating the corrugated gasket 10 and the secondary slider 11. The number is set according to needs and is evenly distributed along the circumference. The size of the slider groove ensures that the secondary slider 11 can only move radially relative to the secondary synchronizer ring 12.

[0087] Similarly, the speed synchronization of the three-stage driving gear 4 and the transmission shaft 17 is achieved through the combined structure of the three-stage positioning ring 13, the three-stage corrugated gasket 14, the three-stage slider 15, and the three-stage synchronization ring 16. In the specific implementation, the structure and function of the three-stage positioning ring 13, the three-stage corrugated gasket 14, the three-stage slider 15, and the three-stage synchronization ring 16 are the same as those of the two-stage positioning ring 9, the two-stage corrugated gasket 10, the two-stage slider 11, and the two-stage synchronization ring 12, and are not repeated here.

[0088] In this embodiment, the transmission shaft 17 is as follows Figure 7As shown, the transmission shaft 17 includes: a shaft body, a primary external spline, a secondary external spline, a secondary transition section, a tertiary external spline, and a tertiary transition section arranged in sequence from the input end of the shaft body; wherein the diameters of the secondary transition section and the tertiary transition section are smaller than the minor diameter of the internal spline of the gear, a plurality of secondary slides are circumferentially arranged at a preset position of the secondary external spline, and a sliding groove is arranged at the position of each secondary slide in the secondary transition section; the structure of the tertiary external spline and the tertiary transition section are similar to those of the secondary external spline and the secondary transition section.

[0089] The working principle of the above variable displacement three-stage gear pump provided in this implementation example is:

[0090] The primary external spline in the transmission shaft 17 is always in meshing state with the internal spline of the primary driving gear 2 during operation, thereby driving the primary driving gear and the primary driven gear to work, and is used to ensure the minimum flow required by the product. It should be noted that the length of the primary spline in the transmission shaft 17 is not less than the sum of the lengths of the internal splines of the three driving gears (including the primary driving gear 2, the secondary driving gear 3, and the tertiary driving gear 4).

[0091] The secondary external spline in the transmission shaft 17 meshes with the secondary driving gear 3 during operation, and the number of spline teeth of the secondary external spline is equal to the number of teeth of the primary external spline minus the number of secondary slides (i.e., secondary sliders), and the reduced number of spline teeth is used to process the secondary sliding groove in the transmission shaft 17; the front end of the secondary external spline in the transmission shaft 17 has the same bevel spline as the front end of the internal spline of the secondary synchronizer ring 12; the length of the secondary external spline in the transmission shaft 17 is not less than the sum of the lengths of the internal spline of the secondary driving gear 3 and the internal spline of the tertiary driving gear 4.

[0092] The three-stage external spline in the transmission shaft 17 meshes with the three-stage driving gear 4 during operation, and the number of spline teeth of the three-stage external spline is equal to the number of teeth of the first-stage external spline minus the number of the three-stage slides (i.e., the three-stage sliders), and the reduced number of spline teeth is used to process the three-stage sliding groove in the transmission shaft 17; the front end of the three-stage external spline in the transmission shaft 17 has the same bevel spline as the front end of the internal spline of the three-stage synchronizer ring 16; the length of the three-stage external spline in the transmission shaft 17 is not less than the length of the internal spline of the three-stage driving gear 4.

[0093] It should be noted that the angles of the secondary ramp and the tertiary ramp in the transmission shaft 17 ensure engagement with the secondary slider 11 and the tertiary slider 15; in addition, the sliding groove in the transmission shaft 17 starts at the end of the tertiary ramp and ends at the beginning of the secondary ramp, and its width and depth dimensions ensure that the secondary slider 11 and the tertiary slider 15 can move axially relative to the transmission shaft. Furthermore, the transmission input in the transmission shaft 17 is a guarantee for transmitting the power source to each mating spline.

[0094] Furthermore, the secondary ramp ( Figure 7b) is meshed with the ramp in the secondary slider 11, and the secondary slider 11 is placed in the placement groove of the secondary synchronizer ring 12, ensuring that when the transmission shaft 17 moves, the secondary corrugated gasket 10, the secondary slider 11, and the secondary synchronizer ring 12 all move synchronously. The assembly enlarged diagram is shown in FIG. Figure 4 The assembly of the three-stage driving gear 4, the three-stage slider 15 and the three-stage synchronizing ring 16 is consistent with the above.

[0095] The working principle of the variable displacement multi-stage gear pump provided in this implementation example is:

[0096] When the demand is for a small flow rate, the transmission shaft 17 is only meshed with the internal spline of the primary driving gear 2 to drive the primary driving gear 2 and the primary driven gear 6 to discharge the required flow rate. The internal splines of the transmission shaft 17 and the secondary driving gear 3 and the tertiary driving gear 4 are in a non-meshing state, so the transmission shaft only transmits power to the primary driving gear.

[0097] When the demand changes from a small flow rate to a medium flow rate, a force is applied to the transmission shaft 17 to make it move circumferentially toward the secondary driving gear 3, thereby driving the secondary corrugated gasket 10, the secondary slider 11, and the secondary synchronizer ring 12 to move. When the outer conical surface of the secondary synchronizer ring 12 contacts the inner conical surface of the secondary driving gear 3, since both conical surfaces are coated with high-friction materials, the friction force drives the secondary driving gear 3 to rotate. At this time, the bevel spline at the front end of the secondary external spline in the transmission shaft 17 and the bevel spline at the front end of the internal spline of the secondary synchronizer ring 12 are in meshing state. This process continues until the rotation speed of the secondary driving gear 3 is the same as that of the transmission shaft 17, and the dynamic friction between the two conical surfaces is transformed into static friction. At this time, the transmission shaft 17 overcomes the force exerted by the ramp of the secondary slider 11 to press the ramp down, and the transmission shaft 17 continues to move upward. The bevel spline at the front end of its secondary external spline is pre-engaged with the bevel spline at the front end of the internal spline of the secondary driving gear 3. The transmission shaft 17 continues to move upward until the secondary external spline is fully engaged with the internal spline of the secondary driving gear 3. At this time, the gear pump discharge flow meets the medium flow demand, and the transmission shaft 17 needs to transmit power to the primary driving gear and the secondary driving gear. The third-stage driving gear is still in a stationary state.

[0098] When the required flow rate changes from medium flow rate to large flow rate, the force is continuously applied to the transmission shaft 17, and the outer cone surface of the three-stage synchronization ring 16 contacts the inner cone surface of the three-stage driving gear 4 to drive the three-stage driving gear to rotate until the rotation speed is the same as that of the transmission shaft. The transmission shaft 17 applies force to overcome the inclined platform of the three-stage slider 15 to press the inclined platform down, and the bevel spline at the front end of the three-stage external spline of the transmission shaft 17 pre-engages with the bevel spline of the inner spline of the three-stage driving gear until it is fully engaged. At this time, the transmission shaft 17 needs to transmit power to the first-stage driving gear 2, the second-stage driving gear 3 and the third-stage driving gear 4 at the same time, and the displacement at this time is also the maximum working displacement of the gear pump.

[0099] When the required flow rate changes from a large flow rate to a medium flow rate, a force is applied to the transmission shaft 17 to make it move axially toward the primary driving gear, the synchronization ring 16 moves downward and contacts the tertiary positioning ring 13, the tertiary driving gear 4 pops open the tertiary slider 15, and the tertiary external spline of the transmission shaft 17 is disengaged from the internal spline of the synchronization ring. At this time, the speed of the tertiary driving gear slowly decreases until it reaches zero. At this time, the transmission shaft still drives the primary gear 3 and the secondary gear 4 to discharge the required flow rate outward.

[0100] When the required flow rate changes from medium flow rate to small flow rate, the force is continuously applied to the transmission shaft 17, the secondary synchronization ring 12 moves downward and contacts the secondary positioning ring 9, the secondary corrugated gasket 10 pops open the secondary slider 11, and the secondary external spline of the transmission shaft 17 is disengaged from the internal spline of the synchronization ring. At this time, the speed of the secondary driving gear slowly decreases until it reaches zero. At this time, the transmission shaft still drives the primary gear to discharge the required flow rate outward.

[0101] Application Cases

[0102] At present, aircraft engines have increasingly stringent requirements on the performance of fuel control systems such as high temperature resistance, high reliability, and long life. Among them, temperature has the most significant impact on the above performance. The main reason for the large temperature rise of the fuel control system is that cruising and slow driving account for 80% or even more of the total life of aircraft engines, and the fuel consumption is the least in these two states. The gear pump generates heat by working on a large amount of high-pressure fuel, which causes a large temperature rise in the fuel system. Therefore, the demand for variable displacement gear pumps is becoming more and more urgent. According to relevant literature, European and American countries have been conducting research in this direction for many years, but the designed gear pumps require special regulators for adjustment, which increases the difficulty of adjustment, increases the weight of the system, and is difficult to apply in the engineering field. An embodiment of the present invention provides a new variable displacement multi-stage gear pump, which changes the displacement of the gear pump by adjusting the position of the drive shaft. Figure 8 , which is a schematic diagram of the application of a variable displacement multi-stage gear pump provided by an embodiment of the present invention in a power input device.

[0103] The method of using the variable displacement multi-stage gear pump provided by this implementation example is as follows:

[0104] (1) The rotation of the spline shaft connected to the power input device drives the actuator and the transmission shaft to rotate synchronously. The transmission shaft is meshed with the primary driving gear in the initial stage. When the required flow rate is a small flow rate, the initial position of the transmission shaft can meet the flow requirement;

[0105] (2) When the required flow rate increases to the intermediate state, hydraulic oil under a certain pressure is introduced into the oil nozzle to move the secondary gear of the transmission shaft. The secondary synchronizer ring drives the secondary gear to rotate pre-rotate. At this time, the conical front end of the secondary spline of the transmission shaft is pre-engaged with the synchronizer ring until the speed of the secondary gear is consistent with that of the transmission shaft. The transmission shaft ramp presses down the slider and the ramp continues to move so that the front end of the secondary spline is engaged with the conical front end of the secondary gear until the spline is fully engaged. At this time, the primary gear and the secondary gear rotate synchronously and the discharge flow rate is the medium flow demand.

[0106] (3) When the required flow increases to the maximum state, a higher pressure hydraulic oil is introduced into the oil nozzle to move the transmission shaft toward the third-stage gear. The third-stage synchronous ring drives the third-stage gear to rotate pre-rotate. At this time, the tapered front end of the third-stage spline of the transmission shaft is pre-engaged with the synchronous ring until the rotation speed of the third-stage gear is consistent with that of the transmission shaft. The transmission shaft inclined table presses down the slider and the inclined table continues to move so that the front end of the third-stage spline is engaged with the tapered front end of the third-stage gear until the spline is fully engaged. At this time, the three pairs of gears rotate synchronously and the discharge flow is the maximum flow demand.

[0107] (4) When the required flow rate decreases from the maximum to the medium state, the hydraulic oil reduces the pressure to a certain value, the transmission shaft moves under the action of the spring force, the third-stage external spline is disengaged from the third-stage gear internal spline, and the third-stage gear gradually reduces the speed to 0. At this time, the second-stage gear and the first-stage gear are still working, and the discharge flow rate is medium.

[0108] (5) When the flow rate drops from medium flow to low flow, the working mechanism is the same.

[0109] Although the embodiments disclosed in the present invention are as above, the contents are only embodiments adopted to facilitate understanding of the present invention and are not intended to limit the present invention. Any technician in the field to which the present invention belongs can make any modifications and changes in the form and details of implementation without departing from the spirit and scope disclosed in the present invention, but the patent protection scope of the present invention shall still be subject to the scope defined in the attached claims.

Claims

1. A variable displacement multistage gear pump, characterized in that: include: A gear pump housing (5), a driving gear assembly and a driven gear assembly disposed in the gear pump housing (5) and meshing with each other, and a transmission shaft (17) sleeved in the driving gear assembly; The driving gear assembly and the driven gear assembly are arranged as a multi-stage gear structure with the same number of stages, and the driving gear assembly and the driven gear assembly include at least two stages of gears meshing with each other; the driving gear assembly includes at least a primary driving gear (2) and a secondary driving gear (3) which are sequentially sleeved on a transmission shaft (17); the driven gear assembly includes at least a primary driven gear (6) for meshing with the primary driving gear (2), and a secondary driven gear (7) for meshing with the secondary driving gear (3); The shaft body of the transmission shaft (17) is provided with at least a primary external spline and a secondary external spline on the outside. The primary driving gear (2) sleeved on the transmission shaft (17) is always in meshing state with the primary external spline on the transmission shaft (17) through its internal spline, so that the primary driving gear (2) and the primary driven gear (6) are driven to work by the rotation of the transmission shaft (17), so as to ensure the minimum flow required by the gear pump; the secondary external spline on the transmission shaft (17) is in meshing state with the secondary driving gear (3) by the movement of the transmission shaft (17) along its axial direction, so that the secondary driving gear (3) and the secondary driven gear (7) are driven to work synchronously with the primary driving gear (2) and the primary driven gear (6) by the rotation of the transmission shaft (17).

2. The variable displacement multistage gear pump according to claim 1, characterized in that: The first-stage driving gear (2) is configured as an annular cylindrical structure with internal splines, and the outer ring of the annular boss provided on the outer cylindrical surface thereof is formed with external meshing teeth for meshing and rotating with the first-stage driven gear (6); the gear ruler width of the first-stage driving gear (2) is determined by the small flow working condition of the gear pump.

3. The variable displacement multistage gear pump according to claim 1, characterized in that: Also includes: A secondary positioning assembly for synchronizing the rotational speed of a secondary driving gear (3) and a transmission shaft (17); The secondary positioning assembly comprises: a secondary positioning ring (9), a secondary corrugated gasket (10), a secondary slider (11), and a secondary synchronization ring (12); The secondary driving gear (3) is configured as a ring-shaped columnar structure as a whole, and the middle part of the inner column wall thereof has an internal spline, and the end of the internal spline close to the primary driving gear (2) is provided with a conical front end, and the rear end of the internal spline has a friction inner cone cavity and a positioning ring groove, and the outer ring of the annular shoulder provided on the outer cylindrical surface thereof forms external meshing teeth for meshing and rotating with the secondary driven gear (7); and the width of the secondary driving gear (3) is determined according to the medium flow condition and the width of the primary driving gear (2); The secondary synchronizer ring (12) is configured as an annular structure with a conical surface, and a plurality of slider grooves are provided on the inner cylindrical surface thereof in the circumferential direction, and are used to place a secondary corrugated gasket (10) and a secondary slider (11) in each slider groove. The secondary synchronizer ring (12) with the secondary corrugated gasket (10) and the secondary slider (11) is integrally installed in the friction inner cone cavity of the secondary driving gear (3), and the secondary positioning ring (9) is installed in the positioning ring groove, and is used to limit the axial installation position of the secondary synchronizer ring (12); the conical end of the secondary synchronizer ring (12) is provided with an internal spline and a conical front end; The secondary slider (11) has a conical inclined platform, which cooperates with the secondary spline on the transmission shaft (17) through the conical inclined platform. The rotation of the transmission shaft (17) drives the secondary slider (11) and the secondary synchronizer ring (12) to rotate, and the secondary slider on the secondary spline is used to limit the axial position of the secondary spline in the transmission shaft (17).

4. The variable displacement multistage gear pump according to claim 3, characterized in that: The transmission shaft (17) comprises: a shaft body, a primary external spline, a secondary external spline, and a secondary transition section arranged in sequence from the input end of the shaft body; wherein the diameter of the secondary transition section is smaller than the minor diameter of the internal spline of the gear, the secondary external spline is provided with a plurality of secondary ramps along the circumferential direction, and the secondary transition section is provided with a secondary sliding groove starting from the position of the secondary ramp for avoiding the secondary slider (11) during installation; and the plurality of secondary ramps are used for limiting the plurality of secondary sliders (11) in a one-to-one correspondence.

5. The variable displacement multistage gear pump according to claim 4, characterized in that: The variable displacement multi-stage gear pump is used to drive the secondary slider (11) and the secondary synchronizing ring (12) to synchronously move axially during the axial movement of the transmission shaft (17) toward the secondary driving gear (3), until the conical end surface of the secondary synchronizing ring (12) abuts against the end of the friction inner conical surface of the secondary driving gear (3), and the friction force generated by the two friction surfaces drives the secondary driving gear (3) to rotate, until the rotation speed of the secondary driving gear (3) is the same as that of the transmission shaft (17), the dynamic friction is converted into static friction, and the secondary inclined table on the transmission shaft (17) pushes the secondary slider (11) to overcome the elastic force of the secondary corrugated gasket (10) and then move radially, so that the transmission shaft (17) continues to move axially toward the secondary driving gear (3), until the secondary external spline is meshed with the internal spline of the secondary driving gear (3) and the internal spline of the secondary synchronizing ring (12), driving the secondary driving gear (3) to rotate synchronously.

6. The variable displacement multistage gear pump according to any one of claims 1 to 5, characterized in that: The driving gear assembly further comprises: a three-stage driving gear (4) sleeved on the transmission shaft (17); the driven gear assembly further comprises: a three-stage driven gear (8) for meshing with the three-stage driving gear (4); the shaft body of the transmission shaft (17) is further provided with a three-stage external spline; The transmission shaft (17) moves along its axial direction so that the third-stage external splines on the transmission shaft (17) and the third-stage driving gear (4) are in meshing state, so that the third-stage driving gear (4) and the third-stage driven gear (8), the second-stage driving gear (3) and the second-stage driven gear (7), and the first-stage driving gear (2) and the first-stage driven gear (6) are driven to work synchronously through the rotation of the transmission shaft (17).

7. The variable displacement multistage gear pump according to claim 6, characterized in that: Also includes: A three-stage positioning assembly for synchronizing the rotation speed of a three-stage driving gear (4) and a transmission shaft (17); The three-stage positioning assembly comprises: a three-stage positioning ring (13), a three-stage corrugated gasket (14), a three-stage slider (15), and a three-stage synchronization ring (16); The three-stage driving gear (4) is configured as a ring-shaped columnar structure as a whole, and has an internal spline in the middle of its inner column wall, and a conical front end is provided at one end of the internal spline close to the second-stage driving gear (3), and a friction inner cone cavity and a positioning ring groove are provided at the rear end of the internal spline, and an annular shoulder outer ring provided on its outer cylindrical surface forms external meshing teeth for meshing and rotating with the three-stage driven gear (8); and the width of the three-stage driving gear (3) is determined by the rated flow of the product and the widths of the first-stage driving gear (2) and the second-stage driving gear (3); The three-stage synchronizer ring (16) is configured as a ring structure with a conical surface, and a plurality of slider grooves are provided on the inner cylindrical surface thereof in the circumferential direction, and a three-stage corrugated gasket (14) and a three-stage slider (15) are placed in each slider groove. The three-stage synchronizer ring (16) with the three-stage corrugated gasket (14) and the three-stage slider (15) is integrally installed in the friction inner cone cavity of the three-stage driving gear (4), and the three-stage positioning ring (13) is installed in the positioning ring groove, and is used to limit the axial installation position of the three-stage synchronizer ring (16); the conical end of the three-stage synchronizer ring (16) is provided with an internal spline and a conical front end; The three-stage slider (15) has a conical inclined platform, which cooperates with the three-stage spline on the transmission shaft (17) through the conical inclined platform. The three-stage slider (15) and the three-stage synchronous ring (16) are driven to rotate by the rotation of the transmission shaft (17), and the axial position of the three-stage spline in the transmission shaft (17) is limited by the three-stage slider on the three-stage spline.

8. The variable displacement multistage gear pump according to claim 7, characterized in that: The transmission shaft (17) further comprises: a three-stage external spline and a three-stage transition section from the two-stage transition section to the shaft end; wherein the diameter of the three-stage transition section is smaller than the minor diameter of the gear internal spline; a plurality of three-stage slides are circumferentially arranged at a preset position of the three-stage external spline; a three-stage sliding groove is arranged at the position of each three-stage slide in the three-stage transition section for avoiding the three-stage slider (15) during installation; and the plurality of three-stage slides are used for limiting the plurality of three-stage sliders (15) in a one-to-one correspondence.

9. The variable displacement multistage gear pump according to claim 8, characterized in that: The variable displacement multi-stage gear pump is used to drive the three-stage slider (15) and the three-stage synchronizing ring (16) to synchronously move axially during the axial movement of the transmission shaft (17) toward the three-stage driving gear (4), until the conical end surface of the three-stage synchronizing ring (16) abuts against the end of the friction inner conical surface of the three-stage driving gear (4), and the friction force generated by the two friction surfaces drives the three-stage driving gear (4) to rotate, until the rotation speed of the three-stage driving gear (4) is the same as that of the transmission shaft (17), the dynamic friction is converted into static friction, and the three-stage slide on the transmission shaft (17) pushes the three-stage slider (15) to overcome the elastic force of the three-stage driving gear (4) and then move radially, so that the transmission shaft (17) continues to move axially toward the three-stage driving gear (4), until the three-stage external spline is meshed with the internal spline of the three-stage driving gear (4) and the internal spline of the three-stage synchronizing ring (16), driving the three-stage synchronizing ring (16) and the three-stage driving gear (4) to rotate synchronously.

10. The variable displacement multi-stage gear pump according to claim 9, characterized in that: The number of teeth of the secondary external spline in the transmission shaft (17) is equal to the number of teeth of the primary external spline minus the number of secondary slides, and the reduced number of spline teeth is used to process the secondary sliding groove in the transmission shaft (17); the front end of the secondary external spline in the transmission shaft (17) has a bevel spline that is the same as the front end of the internal spline of the secondary synchronization ring (12), and is used for pre-synchronization with the internal spline of the secondary gear; the length of the secondary external spline in the transmission shaft (17) is not less than the sum of the lengths of the internal spline of the secondary driving gear (3) and the internal spline of the tertiary driving gear (4); The number of spline teeth of the third-level external spline in the transmission shaft (17) is equal to the number of teeth of the first-level external spline minus the number of the third-level slides, and the reduced number of spline teeth is used to process the third-level sliding groove in the transmission shaft (17); the front end of the third-level external spline in the transmission shaft (17) has a conical spline that is the same as the front end of the internal spline of the third-level synchronization ring (16); the length of the third-level external spline in the transmission shaft (17) is not less than the length of the internal spline of the third-level driving gear (4).

Images