Duplex gear pump

Abstract

The utility model provides a duplex gear pump, which belongs to the technical field of gear pumps and comprises a pump body, a gear box, a high-pressure chamber and a low-pressure chamber, a driving gear shaft and a driving-driven gear shaft which are parallel in the vertical direction are arranged in the high-pressure chamber; an auxiliary driven gear shaft and an auxiliary driving gear shaft which are parallel in the vertical direction are arranged in the low-pressure chamber; the axes of the driving gear shaft, the main driven gear shaft, the auxiliary driving gear shaft and the auxiliary driven gear shaft are sequentially connected to form a quadrangle; the driving gear shaft and the auxiliary driving gear shaft are diagonally opposite, and the driving driven gear shaft and the auxiliary driven gear shaft are diagonally opposite; a transmission gear set is arranged in the gear box and comprises a main transmission gear and an auxiliary transmission gear which are meshed with each other. The main transmission gear is installed on the driving gear shaft, the auxiliary transmission gear is installed on the auxiliary driving gear shaft, and the main transmission gear and the auxiliary transmission gear are diagonally arranged. The gear pump is compact in structure, energy loss can be reduced, and the supercharging effect of the gear pump is achieved.

Description

Technical Field

[0001] The utility model belongs to the technical field of gear pumps, and in particular relates to a double gear pump. Background Art

[0002] As the requirements for liquid pressure in the process flow continue to increase, the high-pressure design of gear pumps has become an inevitable trend in the development of the industry. The duplex gear pump is composed of two-stage gear pumps connected in series, which has the characteristics of high speed, high pressure and large flow to meet the needs of the market.

[0003] However, most multi-gear oil pumps currently on the market use the driving gear shaft (front end) of the previous pump as the connection to the engine, thereby driving the rotation of the middle and rear pumps. This two-stage series gear pump structure is not compact, takes up a lot of space, and wastes space resources. This uncomplicated structure also leads to significant energy loss during transmission, resulting in high boost energy consumption and unsatisfactory boosting results. Utility Model Content

[0004] The embodiment of the utility model provides a double gear pump, which solves the problem that the current double gear pump has a non-compact structure, occupies a large space, has a large boost loss and ultimately leads to a poor boost effect.

[0005] To achieve the above-mentioned purpose, the technical solution adopted by the utility model is: to provide a double gear pump, comprising: a pump body and a gear box, having a high-pressure chamber and a low-pressure chamber connected in the left and right directions; a driving gear shaft and a main and driven gear shaft parallel to each other in the upper and lower directions are provided in the high-pressure chamber; a secondary driven gear shaft and a secondary driving gear shaft parallel to each other in the lower and upper directions are provided in the low-pressure chamber; the axes of the driving gear shaft, the main and driven gear shafts, the secondary driving gear shaft and the secondary driven gear shaft are connected in sequence to form a quadrilateral shape; the driving gear shaft is diagonal to the secondary driving gear shaft, and the main and driven gear shafts are diagonal to the secondary driven gear shaft; the gear box is fixed to the rear side of the pump body, and a transmission gear set is provided in the gear box, and the transmission gear set includes a main transmission gear and a slave transmission gear that mesh with each other; the main transmission gear is mounted on the driving gear shaft, and the slave transmission gear is mounted on the secondary driving gear shaft so that the main transmission gear is diagonal to the slave transmission gear.

[0006] In one possible implementation, a high-pressure gear set is provided in the high-pressure chamber; the high-pressure gear set includes a driving gear and a master-driven gear meshing in the vertical direction; the front and rear ends of the driving gear shaft are respectively rotatably connected to the pump body through bearings and extend rearward into the gear box, and the main transmission gear and the driving gear are mounted on the driving gear shaft; the front and rear ends of the master-driven gear shaft are respectively rotatably connected to the pump body through bearings, and the master-driven gears are mounted on the master-driven gear shafts;

[0007] A low-pressure gear set is provided in the low-pressure chamber; the low-pressure gear set includes a secondary driven gear and a secondary driving gear meshing in the upper and lower directions; the front and rear ends of the secondary driving gear shaft are respectively connected to the pump body through bearings for rotation and extend backward into the gear box, and the slave transmission gear and the secondary driving gear are mounted on the secondary driving gear shaft; the front and rear ends of the secondary driven gear shaft are respectively connected to the pump body through bearings for rotation, and the secondary driven gear is mounted on the secondary driven gear shaft.

[0008] In one feasible manner, an end cover is provided at the front end of the pump body, a front mounting hole through which the driving gear shaft passes is provided on the end cover at a position corresponding to the driving gear shaft, a first front oil tank is provided on the inner side surface of the end cover at a position corresponding to the master and slave gear shafts, a second front oil tank is provided on the inner side surface of the end cover at a position corresponding to the slave driving gear shaft, and a third front oil tank is provided on the inner side surface of the end cover at a position corresponding to the slave driven gear shaft; a first communicating channel is provided between the first front oil tank and the second front oil tank, and a second communicating channel is provided between the third front oil tank and the front mounting hole.

[0009] In one feasible manner, a first rear mounting hole, a second rear mounting hole, a first rear oil tank and a second rear oil tank are provided on the front end surface of the gear box; the driving gear shaft passes through the first rear mounting hole rearward; the auxiliary driving gear shaft passes through the second rear mounting hole rearward, the first rear oil tank corresponds to the master and driven gear shafts, the second rear oil tank corresponds to the auxiliary driven gear shaft, and a third connecting channel is provided between the first rear oil tank and the second rear oil tank.

[0010] In one achievable manner, the diameter of each oil containing groove is larger than the diameter of the corresponding gear shaft; and the width of each connecting channel is smaller than the diameter of each oil containing groove.

[0011] In one achievable manner, a skeleton oil seal is provided in the front mounting hole, and the skeleton oil seal is sealed on the driving gear shaft.

[0012] In one achievable manner, a front sealing ring is provided between the end cover and the pump body, and a rear sealing ring is provided between the pump body and the gear box.

[0013] In one practicable manner, a box cover is provided on the rear side of the gear box, and an annular stop that fits against the inner wall of the gear box is provided on the inner side surface of the box cover.

[0014] In one achievable manner, the rear end of the driving gear shaft is provided with a main pressure cover for axially limiting the main transmission gear; the rear end of the auxiliary driving gear shaft is provided with a slave pressure cover for axially limiting the slave transmission gear.

[0015] The double gear pump provided by the present invention has the following beneficial effects compared with the prior art: the axes of the driving gear shaft, the main and driven gear shafts, the secondary driving gear shaft and the secondary driven gear shaft of the present invention are connected in sequence to form a quadrilateral shape; the driving gear shaft and the secondary driving gear shaft are arranged diagonally, the main and driven gear shafts and the secondary driven gear shaft are arranged diagonally, and the main transmission gear and the secondary transmission gear are arranged diagonally. The series structure of the two-stage gear pump is compact, which can reduce the external volume, reduce the occupied space, save space, and reduce the waste of space resources; and due to the compact structure, it can reduce the loss of energy transmission, thereby increasing the energy used for supercharging, and ultimately achieving the effect of improving the supercharging effect of the gear pump. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 A schematic diagram of the explosion structure of a double gear pump provided in an embodiment of the present utility model;

[0017] Figure 2 A front structural diagram of a double gear pump provided in an embodiment of the present utility model;

[0018] Figure 3 For the Figure 2 Cross-sectional structural diagram along line AA;

[0019] Figure 4 For the Figure 2 Cross-sectional structural diagram along line BB;

[0020] Figure 5 A schematic top view of the double gear pump provided in an embodiment of the present utility model;

[0021] Figure 6 For the Figure 5 Cross-sectional structural diagram along the CC line;

[0022] Figure 7 A schematic diagram of the layout structure of the master-slave transmission gears provided in an embodiment of the present utility model;

[0023] Figure 8 A schematic diagram of the three-dimensional structure of a pump body provided in an embodiment of the utility model;

[0024] Figure 9 A schematic diagram of the structure of the self-lubricating channel on the end cover provided by an embodiment of the utility model;

[0025] Figure 10 for Figure 9 Schematic diagram of the layout structure of the self-lubricating channel and the high and low pressure gear sets provided in the embodiment;

[0026] Figure 11 A schematic diagram of the structure of the self-lubricating channel on the gear box provided by an embodiment of the utility model;

[0027] Figure 12 for Figure 11 Schematic diagram of the layout structure of the self-lubricating channel and the high and low pressure gear sets provided in the embodiment;

[0028] Description of reference numerals:

[0029] 1. End cover; 101. First front oil tank; 102. Second front oil tank; 103. Third front oil tank; 104. First connecting channel; 105. Second connecting channel; 106. Front mounting hole; 2. Pump body; 201. Oil inlet; 202. Connecting hole; 203. Oil outlet; 204. Low-pressure chamber; 205. High-pressure chamber; 3. Secondary driven gear shaft; 4. Gearbox; 401. First rear oil tank; 40 2. Second rear oil tank; 403. Third connecting channel; 404. First rear mounting hole; 405. Second rear mounting hole; 5. Tank cover; 6. Slave transmission gear; 7. Slave pressure cover; 8. Bearing; 9. Auxiliary driving gear shaft; 10. Driving gear shaft; 11. Main transmission gear; 12. Master and slave gear shafts; 13. Main pressure cover; 14. Driving gear; 15. Master and slave gears; 16. Auxiliary driving gear; 17. Auxiliary driven gear. DETAILED DESCRIPTION

[0030] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0031] In this application, terms such as "first" and "second" are merely used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual quantity, priority or sequence relationship between these entities or operations.

[0032] In the claims, specification and above-mentioned drawings of the present utility model, the terms "upper", "lower", "front", "rear", "left", "right", "inner", "outer", "axial", "radial", "circumferential" and the like indicating directions or positional relationships are based on the positions of the gear pump in normal use. The directions and positional relationships shown in the drawings are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction or be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the specific scope of protection of the present invention.

[0033] Please also refer to Figures 1 to 12 Now, the double gear pump provided by the utility model is described. The double gear pump comprises a pump body 2 and a gear box 4, having a high-pressure chamber 205 and a low-pressure chamber 204 connected in the left and right directions; a driving gear shaft 10 and a main driven gear shaft 12 parallel to each other in the upper and lower directions are provided in the high-pressure chamber 205; a sub-driven gear shaft 3 and a sub-driving gear shaft 9 parallel to each other in the upper and lower directions are provided in the low-pressure chamber 204; the axes of the driving gear shaft 10, the main driven gear shaft 12, the sub-driving gear shaft 9 and the sub-driven gear shaft 3 are connected in sequence to form a quadrilateral shape; the driving gear shaft 10 is diagonal to the sub-driving gear shaft 9, and the main driven gear shaft 12 is diagonal to the sub-driven gear shaft 3; the gear box 4 is fixed to the rear side of the pump body 2, and a transmission gear set is provided in the gear box 4, the transmission gear set includes a main transmission gear 11 and a sub-transmission gear 6 that mesh with each other; the main transmission gear 11 is mounted on the driving gear shaft 10, and the sub-transmission gear 6 is mounted on the sub-driving gear shaft 9 so that the main transmission gear 11 is diagonal to the sub-transmission gear 6.

[0034] The double gear pump provided by the present invention has the following beneficial effects compared with the prior art: the axes of the driving gear shaft 10, the master and slave gear shafts 12, the secondary driving gear shaft 9 and the secondary driven gear shaft 3 of the present invention are connected in sequence to form a quadrilateral shape; the driving gear shaft 10 and the secondary driving gear shaft 9 are arranged diagonally, the master and slave gear shafts 12 and the secondary driven gear shaft 3 are arranged diagonally, and the main transmission gear 11 and the slave transmission gear 6 are arranged diagonally. The series structure of the two-stage gear pump is compact, which can reduce the external volume, reduce the occupied space, save space, and reduce the waste of space resources; and due to the compact structure, it can reduce the loss of energy transmission, thereby increasing the energy used for supercharging, and ultimately achieving the effect of improving the supercharging effect of the gear pump.

[0035] In some embodiments, see Figure 6 and Figure 8 As shown, the left side of the pump body 2 is provided with an oil inlet 201 connected to the low-pressure chamber 204, and the right side of the high-pressure chamber 205 is provided with an oil outlet 203 connected to the high-pressure chamber 205; a connecting hole 202 is provided on the isolation wall between the low-pressure chamber 204 and the high-pressure chamber 205, and the oil inlet 201, the connecting hole 202 and the oil outlet 203 are connected in a straight line. When the oil inlet 201 of the present application is set on the left side of the pump body 2, the oil outlet 203 is set on the right side of the pump body 2, and the connecting hole 202 is provided on the isolation wall formed between the two chambers. The oil inlet 201, the oil outlet 203 and the connecting hole 202 are connected in a straight line, which has a compact structure, reduces energy loss in the medium transfer process, and improves the supercharging effect.

[0036] In some embodiments, see Figures 1 to 8 、 Figure 10 and Figure 12A high-pressure gear set is provided in the high-pressure chamber 205; the high-pressure gear set includes a driving gear 14 and a master driven gear 15 meshing in the vertical direction; the front and rear ends of the driving gear shaft 10 are respectively connected to the pump body 2 through bearings 8 for rotation, and extend backward into the gear box 4, the main transmission gear 11 and the driving gear 14 are mounted on the driving gear shaft 10; the front and rear ends of the master driven gear shaft 12 are respectively connected to the pump body 2 through bearings 8 for rotation, and the master driven gear 15 is mounted on the master driven gear shaft 12 A low-pressure gear set is provided in the low-pressure chamber 204; the low-pressure gear set includes a sub-driven gear 17 and a sub-driving gear 16 that mesh in the upper and lower directions; the front and rear ends of the sub-driving gear shaft 9 are respectively rotatably connected to the pump body 2 through bearings 8, and extend backward into the gear box 4, and the transmission gear 6 and the sub-driving gear 16 are installed on the sub-driving gear shaft 9; the front and rear ends of the sub-driven gear shaft 3 are respectively rotatably connected to the pump body 2 through bearings 8, and the sub-driven gear 17 is installed on the sub-driven gear shaft 3.

[0037] In the present application, each bearing 8 is located in a corresponding chamber of the pump body 2 , and each gear shaft is positioned and supported by the bearing 8 .

[0038] During actual operation, the oil inlet 201 and the oil outlet 203 of the pump body 2 are both connected to the pipeline. The prime mover is connected to the front end of the driving gear shaft 10 extending out of the pump body 2. The driving gear shaft 10 drives the slave transmission gear 6 through the main transmission gear 11, and the slave transmission gear 6 drives the secondary driving gear shaft 9 to rotate. The two driving gear shafts 10 drive their respective meshing driven gear shafts to rotate, sucking the medium into the low-pressure chamber 204 (i.e., the pump chamber where the secondary driving gear shaft 9 is located), and then conveying it to the high-pressure chamber 205 (i.e., the pump chamber where the driving gear shaft 10 is located) after being pressurized by rotation. After secondary rotation and pressurization, it is conveyed to the outlet pipeline.

[0039] See also Figure 6 According to the layout of the gears of the present application, it can be understood that the high-pressure chamber 205 of the present application is an "8"-shaped hole adapted for the high-pressure gear set, and the low-pressure chamber 204 is an "8"-shaped hole adapted for the low-pressure gear set. The two "8"-shaped holes are arranged in series on the left and right. When the oil inlet 201 is set on the right side of the pump body 2, the oil outlet 203 is set on the left side of the pump body 2, and the straight line connecting the oil inlet 201, the oil outlet 203 and the connecting hole 202 is perpendicular to the center line of the gears arranged above and below. The structure is compact, which reduces the energy loss in the medium transmission process and improves the boosting effect.

[0040] In some embodiments, see Figure 1 、 Figure 9 and Figure 10The front end of the pump body 2 is provided with an end cover 1, and a front mounting hole 106 through which the driving gear shaft 10 passes is provided on the end cover 1 at a position corresponding to the driving gear shaft 10, a first front oil groove 101 is provided on the inner side surface of the end cover 1 at a position corresponding to the master and slave gear shafts 12, a second front oil groove 102 is provided on the inner side surface of the end cover 1 at a position corresponding to the slave driving gear shaft 9, and a third front oil groove 103 is provided on the inner side surface of the end cover 1 at a position corresponding to the slave driven gear shaft 3; a first communicating channel 104 is provided between the first front oil groove 101 and the second front oil groove 102, and a second communicating channel 105 is provided between the third front oil groove 103 and the front mounting hole 106.

[0041] The end cover 1 and the pump body 2 are sealed with a lip seal ring, which fits into the "8" shaped hole. Each transmission gear is connected to the corresponding gear shaft with a spline, and then tightened with a gland and hexagon socket bolts.

[0042] In this application, the end cover 1 and the pump body 2 are locked with hexagonal bolts, the pump body 2 and the gear box 4 are locked with hexagonal bolts, and the box cover 5 and the gear box 4 are locked with hexagonal bolts.

[0043] This application provides a front oil tank on the inner side of the end cover 1 and the pump body 2. After the medium passes through the interaxial gap between the bearing 8 and the corresponding gear shaft in the high-pressure chamber 205, it can flow through the connecting channel to the interaxial gap between the bearing 8 and the corresponding gear shaft in the low-pressure chamber 204, and then flow back to the high-pressure chamber 205, completing the self-lubrication of the bearing 8 on the end cover 1 side. Therefore, this application not only reduces the energy loss and space waste caused by the previous need for two pumps in series for pressurization, but also realizes self-lubrication of the bearing 8 on the front side of the pump body 2, avoids dry wear damage, and improves the overall service life.

[0044] In some embodiments, see Figure 1 、 Figure 11 and Figure 12 A first rear mounting hole 404, a second rear mounting hole 405, a first rear oil tank 401 and a second rear oil tank 402 are provided on the front end surface of the gear box 4; the driving gear shaft 10 passes through the first rear mounting hole 404 rearward; the secondary driving gear shaft 9 passes through the second rear mounting hole 405 rearward; the first rear oil tank 401 corresponds to the primary and secondary driven gear shafts 12, the second rear oil tank 402 corresponds to the secondary driven gear shaft 3, and a third connecting channel 403 is provided between the first rear oil tank 401 and the second rear oil tank 402.

[0045] The present application provides a rear oil tank at the joint of the gearbox 4 and the pump body 2. After passing through the interaxial gap between the bearing 8 and the primary and secondary driven gear shafts 12 in the high-pressure chamber 205, the medium flows through the third connecting channel 403 to the interaxial gap between the bearing 8 and the secondary driven gear shaft 3 in the low-pressure chamber 204, completing the lubrication of the two driven gear shafts and the bearing 8 on the gearbox 4 side; the medium flows into the gearbox 4 through the gap between the bearing 8 and the driving gear shaft 10 in the high-pressure chamber 205, lubricates the main transmission gear 11 and the slave transmission gear 6, and then flows to the gap between the bearing 8 and the secondary driving gear shaft 9 in the low-pressure chamber 204, and then flows back to the low-pressure chamber 204, completing the lubrication of the driving gear shaft 10, the secondary driving gear shaft 9 and the bearing 8 on the gearbox 4 side.

[0046] Therefore, the present application not only reduces the energy loss and space waste caused by the previous need for two pumps in series for pressurization, but also can avoid dry wear damage through the self-lubrication of the bearing 8 on the side of the gear box 4, thereby improving the overall service life.

[0047] Therefore, the present application provides oil tanks and connecting channels on the front and rear sides of the pump body 2, which are structures that facilitate self-lubrication, so as to achieve self-lubrication of the bearings 8 at the front and rear ends of each gear shaft, thereby improving the reliability of the gear pump.

[0048] In some embodiments, see Figures 2 to 4 The diameter of each oil containing groove is larger than the shaft diameter of the corresponding gear shaft, so that each oil containing groove and the bearing 8 on the corresponding gear shaft partially overlap in the axial direction to ensure the fluidity of the lubricating oil.

[0049] In some embodiments, see Figure 9 and Figure 11 The width of each connecting channel is smaller than the diameter of each oil containing groove so that the lubricating oil can flow fully.

[0050] In some embodiments, see Figure 3 A skeleton oil seal (not labeled in the figure) is installed in the front mounting hole 106. The skeleton oil seal seals the driving gear shaft 10, forming a seal between the end cover 1 and the driving gear shaft 10 to prevent medium leakage. The skeleton oil seal in the end cover 1 is axially limited by a hole retaining ring.

[0051] In some embodiments, see Figure 1A front sealing ring (not labeled in the figure) is provided between the end cover 1 and the pump body 2, and a rear sealing ring (not labeled in the figure) is provided between the pump body 2 and the gearbox 4. Due to the "8"-shaped shape of the high-pressure chamber 205 and the low-pressure chamber 204, the corresponding sealing rings are all lip-shaped. Annular grooves for mounting the sealing rings are provided at the front and rear ends of the pump body 2. Both the front and rear sealing rings are positioned around the periphery of the high-pressure chamber 205 and the low-pressure chamber 204, ensuring a tight seal between the two chambers and preventing leakage of the medium.

[0052] In some embodiments, see Figure 1 、 Figure 3 and Figure 4 A cover 5 is located behind the gearbox 4. Its inner surface is fitted with an annular stopper (not labeled in the figure) that fits against the inner wall of the gearbox 4. This arrangement of the cover 5 ensures excellent positioning during installation. Specifically, a polyethylene gasket (not labeled in the figure) is used to seal the gearbox 4 and the cover 5, which are secured with hexagonal bolts.

[0053] In some embodiments, see Figures 1 to 4 The rear end of the driving gear shaft 10 is provided with a main pressure cap 13 that axially limits the main transmission gear 11 to prevent the driving gear shaft 10 from falling off; the rear end of the secondary driving gear shaft 9 is provided with a slave pressure cap 7 that axially limits the slave transmission gear 6 to prevent the slave transmission gear 6 from falling off axially. Each pressure cap is fastened by a bolt screwed to the end of the corresponding gear shaft.

[0054] In the above embodiments, the description of each embodiment has its own focus. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant description of other embodiments.

[0055] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A double gear pump, characterized in that: include: The pump body (2) has a low-pressure chamber (204) and a high-pressure chamber (205) connected in the left-right direction; a driving gear shaft (10) and a main driven gear shaft (12) parallel to each other in the vertical direction are arranged in the high-pressure chamber (205); a sub-driven gear shaft (3) and a sub-driving gear shaft (9) parallel to each other in the vertical direction are arranged in the low-pressure chamber (204); The axes of the driving gear shaft (10), the main driven gear shaft (12), the secondary driving gear shaft (9) and the secondary driven gear shaft (3) are connected in sequence to form a quadrilateral shape; the driving gear shaft (10) is diagonally opposite to the secondary driving gear shaft (9), and the main driven gear shaft (12) is diagonally opposite to the secondary driven gear shaft (3); and A gear box (4) is fixed to the rear side of the pump body (2). A transmission gear set is provided in the gear box (4). The transmission gear set includes a main transmission gear (11) and a slave transmission gear (6) that mesh with each other. The main transmission gear (11) is mounted on the driving gear shaft (10), and the slave transmission gear (6) is mounted on the secondary driving gear shaft (9) so that the main transmission gear (11) and the slave transmission gear (6) are diagonally aligned.

2. The double gear pump according to claim 1, characterized in that: An oil inlet (201) communicating with the low-pressure chamber (204) is provided on the left side of the pump body (2), and an oil outlet (203) communicating with the high-pressure chamber (205) is provided on the right side of the high-pressure chamber (205); a connecting hole (202) is provided on the isolation wall between the low-pressure chamber (204) and the high-pressure chamber (205), and the oil inlet (201), the connecting hole (202) and the oil outlet (203) are connected in a straight line.

3. The double gear pump according to claim 1, characterized in that: A high-pressure gear set is provided in the high-pressure chamber (205); the high-pressure gear set comprises a driving gear (14) and a master driven gear (15) meshed in an upper and lower direction; the front and rear ends of the driving gear shaft (10) are respectively rotatably connected to the pump body (2) through bearings (8) and extend rearward into the gear box (4); the main transmission gear (11) and the driving gear (14) are mounted on the driving gear shaft (10); the front and rear ends of the master driven gear shaft (12) are respectively rotatably connected to the pump body (2) through bearings (8), and the master driven gear (15) are mounted on the master driven gear shaft (12); A low-pressure gear set is provided in the low-pressure chamber (204); the low-pressure gear set comprises a secondary driven gear (17) and a secondary driving gear (16) meshed in the upper and lower directions; the front and rear ends of the secondary driving gear shaft (9) are rotatably connected to the pump body (2) through bearings (8) and extend backward into the gear box (4); the driven transmission gear (6) and the secondary driving gear (16) are mounted on the secondary driving gear shaft (9); the front and rear ends of the secondary driven gear shaft (3) are rotatably connected to the pump body (2) through bearings (8), and the secondary driven gear (17) is mounted on the secondary driven gear shaft (3).

4. The double gear pump according to claim 2, characterized in that: The front end of the pump body (2) is provided with an end cover (1); a front mounting hole (106) through which the driving gear shaft (10) passes is provided on the end cover (1) at a position corresponding to the driving gear shaft (10); a first front oil tank (101) is provided on the inner side surface of the end cover (1) at a position corresponding to the master and slave gear shafts (12); a second front oil tank (102) is provided on the inner side surface of the end cover (1) at a position corresponding to the slave driving gear shaft (9); and a third front oil tank (103) is provided on the inner side surface of the end cover (1) at a position corresponding to the slave driven gear shaft (3); a first communicating channel (104) is provided between the first front oil tank (101) and the second front oil tank (102); and a second communicating channel (105) is provided between the third front oil tank (103) and the front mounting hole (106).

5. The double gear pump according to claim 4, characterized in that: The front end surface of the gear box (4) is provided with a first rear mounting hole (404), a second rear mounting hole (405), a first rear oil tank (401) and a second rear oil tank (402); the driving gear shaft (10) passes through the first rear mounting hole (404) backward; the secondary driving gear shaft (9) passes through the second rear mounting hole (405) backward; the first rear oil tank (401) corresponds to the primary and secondary driven gear shafts (12); the second rear oil tank (402) corresponds to the secondary driven gear shaft (3); and a third connecting channel (403) is provided between the first rear oil tank (401) and the second rear oil tank (402).

6. The double gear pump according to claim 5, characterized in that: The diameter of each oil containing groove is larger than the shaft diameter of the corresponding gear shaft; the width of each communication channel is smaller than the diameter of each oil containing groove.

7. The double gear pump according to claim 4, characterized in that: A skeleton oil seal is provided in the front mounting hole (106), and the skeleton oil seal is sealed on the driving gear shaft (10).

8. The double gear pump according to claim 4, characterized in that: A front sealing ring is provided between the end cover (1) and the pump body (2), and a rear sealing ring is provided between the pump body (2) and the gear box (4).

9. The double gear pump according to claim 1, characterized in that: A box cover (5) is provided on the rear side of the gear box (4), and an annular stopper is provided on the inner side surface of the box cover (5) and fits the inner wall of the gear box (4).

10. The double gear pump according to claim 1, characterized in that: The rear end of the driving gear shaft (10) is provided with a main pressure cover (13) for axially limiting the main transmission gear (11); the rear end of the secondary driving gear shaft (9) is provided with a slave pressure cover (7) for axially limiting the slave transmission gear (6).

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