A self-boosting gear pump with low torque fluctuation

Abstract

The present invention discloses a self-boosting gear pump with low torque fluctuation, which relates to the technical field of hydraulic pumps. Its main structure is as follows: between two driving shaft gears and between two driven shaft gears, they are arranged to rotate coaxially, in the same direction and synchronously. Moreover, the meshing teeth of the driving shaft gears and the driven shaft gears located in the lower pump housing are installed with a half-tooth dislocation relative to the meshing teeth of the driving shaft gears and the driven shaft gears located in the upper pump housing. For the self-boosting gear pump with low torque fluctuation provided by the present invention, the periodic change amplitude of the driving force arm of the meshing point relative to the rotation center of the driving shaft will be significantly weakened, thereby reducing the fluctuation amplitude of the input torque and achieving low torque fluctuation of the self-boosting gear pump.

Description

Technical Field

[0001] The invention relates to the technical field of hydraulic pumps, and in particular to a self-pressurizing gear pump with low torque fluctuation. Background Art

[0002] Gear pumps, plunger pumps, and vane pumps are the three major hydraulic pumps in the hydraulic industry. Among them, gear pumps are the most widely used due to their simple structure, small size, strong anti-pollution ability, easy manufacturing and maintenance, and low price. However, due to the problems of large flow pulsation, low working pressure, and unbalanced radial force in gear pumps, their application range is greatly limited. Therefore, gear pumps are mainly used in medium and low pressure application scenarios. However, as the hydraulic system develops towards high response, high power density, etc., high speed and high pressure have become the main development trend of gear pumps.

[0003] To this end, the patent (application number: 202310102797.5) designs a self-pressurizing gear pump, which better meets the development needs of the hydraulic system towards high speed and high pressure, and has a very strong anti-pollution ability - specifically, because the self-pressurizing gear pump can achieve pressure increase and output high-pressure oil through hydraulic oil extrusion when the closed variable volume cavity formed by the meshing of the gears becomes smaller; when the closed variable volume cavity becomes larger, it can be connected to the oil inlet to achieve oil replenishment, so the self-pressurizing gear pump can achieve a higher output pressure, and the cavitation effect is not obvious. At the same time, since the gear rotation circumferential direction in the self-pressurizing gear pump is a circular motion, it can achieve high-speed and high overspeed operation, thereby achieving a higher output flow rate. At the same time, due to the large radial clearance between the "8"-shaped mounting cavity of the self-pressurizing gear pump and the gear tooth top circle, it also has a very strong anti-pollution ability.

[0004] However, during the meshing operation of the gear teeth of the self-pressurizing gear pump in the above patent, the variable volume cavity formed by the meshing point of the gears on the same side of the plane formed by the axes of the gears of the active and driven shafts involved in the meshing, that is, the meshing start side or the meshing disengagement side, is only connected to one of the two distribution waist-shaped openings on the same side. Therefore, when the gears are running continuously, the driving force arm formed by the meshing point relative to the rotation center of the active shaft will inevitably change continuously and periodically, resulting in continuous periodic fluctuations in the input torque. This is extremely unfavorable to the smooth and continuous operation of the drive motor, and will inevitably cause additional power loss of the motor.

[0005] Therefore, a new hydraulic pump is urgently needed to solve the above problems. Summary of the invention

[0006] The object of the present invention is to provide a self-pressurizing gear pump with low torque fluctuation, in which the periodic variation amplitude of the driving force arm of the meshing point relative to the rotation center of the driving shaft will be significantly weakened, thereby reducing the fluctuation amplitude of the input torque and realizing the low torque fluctuation of the self-pressurizing gear pump.

[0007] To achieve the above-mentioned object, the present invention provides a self-pressurizing gear pump with low torque fluctuation, comprising a lower distributor, a lower pump housing, a middle distributor, an upper pump housing and an upper distributor which are arranged in sequence from bottom to top, wherein both the lower pump housing and the upper pump housing are provided with an "8"-shaped mounting cavity, the two "8"-shaped mounting cavities are arranged opposite to each other up and down, and both the two "8"-shaped mounting cavities are horizontally installed with a driving shaft gear and a driven shaft gear meshed with involute gears, the two driving shaft gears and the two driven shaft gears are coaxially, in the same direction, and rotate synchronously, and the meshing teeth of the driving shaft gear and the driven shaft gear in the lower pump housing and the meshing teeth of the driving shaft gear and the driven shaft gear in the upper pump housing are staggered by half a tooth;

[0008] The lower surface and the upper surface of the middle distribution plate are both provided with a middle distribution waist-shaped opening a connected with the variable volume cavity on the engagement start side, and a middle distribution waist-shaped opening b connected with the variable volume cavity on the engagement disengagement side. The middle distribution plate is provided with a middle oil passage a located on the engagement start side and a middle oil passage b located on the engagement disengagement side. One end of the middle oil passage a is connected with the oil port a arranged on the outer side wall of the middle distribution plate, and the other end is connected with the middle distribution waist-shaped opening a. One end of the middle oil passage b is connected with the oil port b arranged on the outer side wall of the middle distribution plate, and the other end is connected with the middle distribution waist-shaped opening b.

[0009] As a further improvement of the present invention, there are two middle flow waist-shaped openings a on the lower surface of the middle flow distribution plate and they are arranged oppositely, and the two middle flow waist-shaped openings a are respectively communicated with the two variable volume chambers on the engagement start side of the lower pump housing, and there are two middle flow waist-shaped openings b on the lower surface of the middle flow distribution plate and they are arranged oppositely, and the two middle flow waist-shaped openings b are respectively communicated with the two variable volume chambers on the engagement and disengagement side of the lower pump housing;

[0010] There are two middle flow waist-shaped openings a on the upper surface of the middle flow distribution disc and they are arranged opposite to each other. The two middle flow waist-shaped openings a are respectively connected to the two variable volume chambers on the starting side of the engagement with the upper pump housing. There are two middle flow waist-shaped openings b on the upper surface of the middle flow distribution disc and they are arranged opposite to each other. The two middle flow waist-shaped openings b are respectively connected to the two variable volume chambers on the engagement and disengagement side of the upper pump housing.

[0011] As a further improvement of the present invention, the upper surface of the lower flow distribution disk is provided with a lower flow distribution waist-shaped port a communicating with the variable volume chamber on the starting side of the engagement with the lower pump housing, and a lower flow distribution waist-shaped port b communicating with the variable volume chamber on the disengaging side of the engagement with the lower pump housing. The lower flow distribution waist-shaped port a is further connected to the middle oil passage a through a lower oil passage a provided in the lower flow distribution disk and a lower connecting oil passage a provided in the lower pump housing. The lower flow distribution waist-shaped port b is further connected to the middle oil passage b through a lower oil passage b provided in the lower flow distribution disk and a lower connecting oil passage b provided in the lower pump housing;

[0012] The lower surface of the upper flow distribution disk is provided with an upper flow distribution waist-shaped port a communicating with the variable volume chamber on the starting side of the engagement with the upper pump housing, and an upper flow distribution waist-shaped port b communicating with the variable volume chamber on the disengaging side of the engagement with the upper pump housing. The upper flow distribution waist-shaped port a is further connected to the middle oil passage a through an upper oil passage a provided in the upper flow distribution disk and an upper connecting oil passage a provided in the upper pump housing. The upper flow distribution waist-shaped port b is further connected to the middle oil passage b through an upper oil passage b provided in the upper flow distribution disk and an upper connecting oil passage b provided in the upper pump housing.

[0013] As a further improvement of the present invention, there are two lower flow distribution waist-shaped ports a on the upper surface of the lower flow distribution disk, which are arranged oppositely. The two lower flow distribution waist-shaped ports a are respectively connected to the two variable volume chambers on the starting side of the engagement with the lower pump housing. There are two lower flow distribution waist-shaped ports b on the upper surface of the lower flow distribution disk, which are arranged oppositely. The two lower flow distribution waist-shaped ports b are respectively connected to the two variable volume chambers on the disengaging side of the engagement with the lower pump housing.

[0014] As a further improvement of the present invention, there are two upper flow distribution waist-shaped ports a on the lower surface of the upper flow distribution disk, which are arranged oppositely. The two upper flow distribution waist-shaped ports a are respectively connected to the two variable volume chambers on the starting side of the engagement with the upper pump housing. There are two upper flow distribution waist-shaped ports b on the lower surface of the upper flow distribution disk, which are arranged oppositely. The two upper flow distribution waist-shaped ports b are respectively connected to the two variable volume chambers on the disengaging side of the engagement with the upper pump housing.

[0015] As a further improvement of the present invention, at the connection of the lower oil passage a and the lower connecting oil passage a, at the connection of the lower connecting oil passage a and the middle oil passage a, at the connection of the lower oil passage b and the lower connecting oil passage b, at the connection of the lower connecting oil passage b and the middle oil passage b, at the connection of the upper oil passage a and the upper connecting oil passage a, at the connection of the upper connecting oil passage a and the middle oil passage a, at the connection of the upper oil passage b and the upper connecting oil passage b, and at the connection of the upper connecting oil passage b and the middle oil passage b, flow channel sealing rings are provided along the joints.

[0016] As a further improvement of the present invention, two lower gear shaft mounting holes for mounting the driving shaft gear and the driven shaft gear are provided on the upper surface of the lower distribution plate, two middle gear shaft mounting holes for mounting the driving shaft gear and the driven shaft gear are provided on the middle distribution plate, and two upper gear shaft mounting holes for mounting the driving shaft gear and the driven shaft gear are provided on the lower surface of the upper distribution plate;

[0017] Bearings for rotatably mounting the gear shafts of the driving shaft gear and the driven shaft gear are provided in the lower gear shaft mounting holes, the middle gear shaft mounting holes, and the upper gear shaft mounting holes.

[0018] As a further improvement of the present invention, the upper gear shaft mounting holes and the middle gear shaft mounting holes for mounting the driving shaft gear are through holes, and a retaining ring and a sealing leather cup sleeved on the gear shaft of the driving shaft gear are sequentially provided from top to bottom in the upper part of the upper gear shaft mounting hole.

[0019] As a further improvement of the present invention, edge sealing rings are provided between the lower distribution plate and the lower pump housing, between the lower pump housing and the middle distribution plate, between the middle distribution plate and the upper pump housing, and between the upper pump housing and the upper distribution plate along the edges of the contact surfaces.

[0020] As a further improvement of the present invention, positioning pin holes and threaded holes are provided on the lower distribution plate, the lower pump housing, the middle distribution plate, the upper pump housing, and the upper distribution plate.

[0021] Compared with the prior art, the advantages of a self-boosting gear pump with low torque fluctuation of the present invention are:

[0022] 1. In this gear pump, by providing upper and lower groups of meshing gear sets that are coaxial, rotate in the same direction, rotate synchronously, and are installed with a half-tooth offset from each other, and cooperating with the middle distribution plate with middle distribution waist-shaped ports a and middle distribution waist-shaped ports b provided on both the upper and lower surfaces, the periodic change amplitude of the driving force arm of the meshing point relative to the rotation center of the driving shaft can be effectively weakened, thereby reducing the fluctuation amplitude of the input torque and realizing low torque fluctuation of the self-boosting gear pump.

[0023] Through the following description and in combination with the drawings, the present invention will become clearer. These drawings are used to explain the embodiments of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0025] Figure 1Explosion diagram of the present invention;

[0026] Figure 2 Stereogram of the lower pump housing of the present invention;

[0027] Figure 3 Stereogram of the middle distribution plate of the present invention;

[0028] Figure 4 Sectional stereogram of the middle distribution plate of the present invention;

[0029] Figure 5 Stereogram of the lower distribution plate of the present invention;

[0030] Figure 6 Sectional stereogram of the lower distribution plate of the present invention;

[0031] Figure 7 Stereogram of the upper distribution plate of the present invention;

[0032] Figure 8 Sectional stereogram of the upper distribution plate of the present invention;

[0033] Figure 9 Schematic diagram of the working principle of the lower distribution plate of the present invention for oil inlet and oil discharge - one;

[0034] Figure 10 Schematic diagram of the working principle of the lower distribution plate of the present invention for oil inlet and oil discharge - two;

[0035] Figure 11 Schematic diagram of the working principle of the lower distribution plate of the present invention for oil inlet and oil discharge - three;

[0036] Figure 12 Schematic diagram of the working principle of the lower distribution plate of the present invention for oil inlet and oil discharge - four;

[0037] Figure 13 Schematic diagram of the change of the force arm of the driving gear torque of the existing self - pressurizing gear pump - one;

[0038] Figure 14 Schematic diagram of the change of the force arm of the driving gear torque of the existing self - pressurizing gear pump - two;

[0039] Figure 15 Schematic diagram of the change of the force arm of the driving shaft gear torque of the present invention - one;

[0040] Figure 16 Schematic diagram of the change of the force arm of the driving shaft gear torque of the present invention - two.

[0041] Wherein: 1 - lower distribution disk; 11 - lower gear shaft mounting hole; 12 - lower oil passage a; 13 - lower oil passage b; 14 - lower distribution kidney-shaped port a; 15 - lower distribution kidney-shaped port b; 16 - lower pump housing; 17 - lower connecting oil passage a; 18 - lower connecting oil passage b; 2 - middle distribution disk; 21 - middle gear shaft mounting hole; 22 - middle oil passage a; 23 - middle oil passage b; 24 - middle distribution kidney-shaped port a; 25 - middle distribution kidney-shaped port b; 26 - oil port a; 27 - oil port b; 3 - upper distribution disk; 31 - upper gear shaft mounting hole; 32 - upper oil passage a; 33 - upper oil passage b; 34 - upper distribution kidney-shaped port a; 35 - upper distribution kidney-shaped port b; 36 - upper pump housing; 37 - upper connecting oil passage a; 38 - upper connecting oil passage b; 4 - driving shaft gear; 41 - retaining ring; 42 - sealing leather cup; 5 - driven shaft gear; 51 - "8"-shaped mounting cavity; 6 - bearing; 7 - runner sealing ring; 8 - edge sealing ring; 9 - positioning pin hole; 91 - threaded hole. Detailed implementation manners

[0042] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Apparently, the described embodiments are some but not all of the embodiments of the present invention. The components of the embodiments of the present invention usually described and illustrated in the drawings here can be arranged and designed in various different configurations.

[0043] Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed present invention, but merely represents selected embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0044] It should be noted that: similar reference numerals and letters denote similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0045] In the description of the embodiments of the present invention, it should be noted that if terms such as "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. are used to indicate the orientation or positional relationship, it is based on the orientation or positional relationship shown in the drawings or the orientation or positional relationship in which the product of the invention is usually placed during use. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention.

[0046] In addition, when terms such as "horizontal", "vertical", "hanging" appear, it does not mean that the components are required to be absolutely horizontal or hanging, but they can be slightly inclined. For example, "horizontal" only means that its direction is more horizontal relative to "vertical", and it does not mean that the structure must be completely horizontal, but it can be slightly inclined.

[0047] In the description of the embodiments of the present invention, "a plurality of" represents at least three.

[0048] In the description of the embodiments of the present invention, it should also be noted that unless otherwise clearly specified and limited, when terms such as "set", "installed", "connected", "connected" appear, they should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0049] Now, the embodiments of the present invention will be described with reference to the accompanying drawings.

[0050] Embodiment

[0051] The specific implementation manner of the present invention is as follows Figure 1 As shown, a self-boosting gear pump with low torque fluctuation includes a lower distribution plate 1, a lower pump housing 16, a middle distribution plate 2, an upper pump housing 36, and an upper distribution plate 3 that are sequentially overlapped from bottom to top. In this embodiment, the self-boosting gear pump composed of the lower distribution plate 1, the lower pump housing 16, the middle distribution plate 2, the upper pump housing 36, and the upper distribution plate 3 has a columnar structure. Among them, "8"-shaped installation cavities 51 are provided in both the lower pump housing 16 and the upper pump housing 36. In this embodiment, the intersection of the two cylindrical surfaces of the "8"-shaped installation cavity 51 is a smooth transition, and the two smooth transition surfaces are symmetrically distributed along the plane formed by the axes of the two cylindrical holes.

[0052] At the same time, the two "8"-shaped installation cavities 51 are arranged vertically opposite to each other, and a driving shaft gear 4 and a driven shaft gear 5 are horizontally installed in both of the two "8"-shaped installation cavities 51. In this implementation, the driving shaft gear 4 and the driven shaft gear 5 are in involute gear engagement, and the driven shaft gear 5 is driven by the driving shaft gear 4 to rotate synchronously. The two driving shaft gears 4 are coaxial, rotate in the same direction, and rotate synchronously, and the two driven shaft gears 5 are also coaxial, rotate in the same direction, and rotate synchronously. Moreover, the meshing teeth of the driving shaft gear 4 and the driven shaft gear 5 in the lower pump housing 16 are installed with a half-tooth offset from the meshing teeth of the driving shaft gear 4 and the driven shaft gear 5 in the upper pump housing 36.

[0053] Regarding the middle distribution plate 2, as Figure 3-4As shown, the lower surface and the upper surface of the middle distribution disk 2 are respectively provided with a middle distribution waist-shaped port a24 communicating with the variable volume chamber on the starting side of meshing and a middle distribution waist-shaped port b25 communicating with the variable volume chamber on the disengaging side of meshing. The middle distribution waist-shaped port a24 and the middle distribution waist-shaped port b25 are arranged oppositely. At the same time, a middle oil passage a22 on the starting side of meshing and a middle oil passage b23 on the disengaging side of meshing are further arranged inside the middle distribution disk 2. One end of the middle oil passage a22 is communicated with an oil port a26 arranged on the outer side wall of the middle distribution disk 2, and the other end is communicated with the middle distribution waist-shaped port a24. One end of the middle oil passage b23 is communicated with an oil port b27 arranged on the outer side wall of the middle distribution disk 2, and the other end is communicated with the middle distribution waist-shaped port b25.

[0054] In this embodiment, there are two middle distribution waist-shaped ports a24 on the lower surface of the middle distribution disk 2 and they are arranged oppositely. The two middle distribution waist-shaped ports a24 are respectively communicated with the two variable volume chambers on the starting side of meshing of the lower pump housing 16. There are two middle distribution waist-shaped ports b25 on the lower surface of the middle distribution disk 2 and they are arranged oppositely. The two middle distribution waist-shaped ports b25 are respectively communicated with the two variable volume chambers on the disengaging side of meshing of the lower pump housing 16. There are two middle distribution waist-shaped ports a24 on the upper surface of the middle distribution disk 2 and they are arranged oppositely. The two middle distribution waist-shaped ports a24 are respectively communicated with the two variable volume chambers on the starting side of meshing of the upper pump housing 36. There are two middle distribution waist-shaped ports b25 on the upper surface of the middle distribution disk 2 and they are arranged oppositely. The two middle distribution waist-shaped ports b25 are respectively communicated with the two variable volume chambers on the disengaging side of meshing of the upper pump housing 36.

[0055] When the driving shaft gear 4 starts to rotate, the oil port a26 of the middle flow distribution disk 2 located at the starting side of the meshing between the driving shaft gear 4 and the driven shaft gear 5 will serve as the oil discharge port, jointly forming the oil discharge cavity of the pump with the middle oil passage a22 and the middle flow distribution waist-shaped port a24. The oil port b27 of the middle flow distribution disk 2 located at the disengaging side of the meshing between the driving shaft gear 4 and the driven shaft gear 5 will serve as the oil inlet port, jointly forming the oil inlet cavity of the pump with the middle oil passage b23 and the middle flow distribution waist-shaped port b25. Specifically, this self-boosting gear pump can gather the oil fluid on both sides of the "8"-shaped mounting cavity 51 towards the starting side of meshing by the rotation of the driving shaft gear 4 and the driven shaft gear 5 which are assembled in the upper and lower "8"-shaped mounting cavities 51 and mesh with each other, thereby self-boosting the oil fluid. Then, in the "variable volume cavity" formed by the meshing of the driving shaft gear 4 and the driven shaft gear 5 at the starting side of meshing, the volume of the variable volume cavity becomes smaller to squeeze and boost the oil fluid for the second time, and the high-pressure oil fluid is output through the middle flow distribution waist-shaped port a24, the middle oil passage a22 and the oil port a26, thus realizing the oil fluid boosting and high-pressure output of the gear pump. At the same time, in the "variable volume cavity" formed by the meshing of the driving shaft gear 4 and the driven shaft gear 5 at the disengaging side of meshing, the "variable volume cavity" will gradually expand to generate suction with the rotation of the driving shaft gear 4 and the driven shaft gear 5, and timely replenish oil to the "variable volume cavity" through the middle flow distribution waist-shaped port b25, the middle oil passage b23 and the oil port b27, without generating local vacuum, effectively avoiding the generation of cavitation.

[0056] Compared with the existing gear pump technology, when the self-boosting gear pump operates with continuous gear meshing, the volume between the inner walls of the upper and lower "8"-shaped cavities 51 and the gear pitch circle on the meshing side becomes smaller, realizing the first-stage boosting of the oil fluid. Then, by using the reduction of the volume of the variable volume cavity formed during continuous gear meshing to squeeze the oil fluid, the second-stage boosting is achieved, thereby greatly increasing its output pressure. Therefore, this self-boosting gear pump can have a higher output pressure without the need for multi-stage series connection of gear pumps, thus avoiding the defects such as complex structure, high manufacturing cost and difficult maintenance caused by multi-stage series connection of gear pumps. At the same time, since the circumferential rotation of the gears in this self-boosting gear pump is circular motion, high-speed and ultra-high-speed operation can be achieved. Therefore, compared with the poor self-priming characteristics of the existing piston pumps at the inlet and the poor self-priming characteristics of the reciprocating linear motion of piston pumps, this self-boosting gear pump realizes a higher output flow rate through the high-speed and ultra-high-speed gear rotation speed. And, compared with the high precision requirements for each mating pair due to the small sealing gaps between the flow distribution disk, the plunger, the slipper, etc. in the existing piston pumps, this self-boosting gear pump has a larger radial clearance between the "8"-shaped mounting cavity 51 and the gear pitch circle, so it has stronger anti-pollution ability and better anti-temperature rise and deformation ability. And the parts also have higher cost advantages in manufacturing and installation.

[0057] Moreover, when the gear pump is operating, in the two groups of middle flow distribution waist-shaped ports a24 on the upper and lower surfaces of the middle flow distribution disk 2 respectively located on the starting side of meshing, one group of middle flow distribution waist-shaped ports a24 communicates with one of the variable volume chambers formed by one group of meshing gear sets, and the other group of middle flow distribution waist-shaped ports a24 communicates with one of the variable volume chambers formed by the other group of meshing gears. In the two groups of middle flow distribution waist-shaped ports b25 on the upper and lower surfaces of the middle flow distribution disk 2 respectively located on the disengaging side of meshing, one group of middle flow distribution waist-shaped ports b25 communicates with one of the variable volume chambers formed by one group of meshing gear sets, and the other group of middle flow distribution waist-shaped ports b25 communicates with one of the variable volume chambers formed by the other group of meshing gears. And, since the two groups of meshing gear sets are arranged to rotate coaxially, in the same direction, and synchronously and are installed with a half-tooth misalignment relative to each other. Therefore, when the gear pump is operating, at a certain time, there is a left-right symmetric relationship between the variable volume chamber communicated with the middle flow distribution waist-shaped port a24 on the upper surface of the middle flow distribution disk 2 and the variable volume chamber communicated with the middle flow distribution waist-shaped port a24 on the lower surface of the middle flow distribution disk 2, and they will discharge oil simultaneously; there is a left-right symmetric relationship between the variable volume chamber communicated with the middle flow distribution waist-shaped port b25 on the upper surface of the middle flow distribution disk 2 and the variable volume chamber communicated with the middle flow distribution waist-shaped port b25 on the lower surface of the middle flow distribution disk 2, and they will intake oil simultaneously.

[0058] Thus, compared with the existing self-boosting gear pump technology, when the gear pump in this embodiment is operating, the periodic change amplitude of the driving force arm of the meshing point relative to the rotation center of the driving shaft will be significantly weakened, thereby reducing the fluctuation amplitude of the input torque, and further enabling low torque fluctuation of the self-boosting gear pump.

[0059] Regarding the lower flow distribution disk 1, as Figure 5-6 shown, in order to increase the oil flow rate, the upper surface of the lower flow distribution disk 1 is provided with a lower flow distribution waist-shaped port a14 communicating with the variable volume chamber on the starting side of meshing of the lower pump housing 16 and a lower flow distribution waist-shaped port b15 communicating with the variable volume chamber on the disengaging side of meshing of the lower pump housing 16. The lower flow distribution waist-shaped port a14 and the lower flow distribution waist-shaped port b15 are oppositely arranged. The lower flow distribution waist-shaped port a14 is also communicated with the middle oil passage a22 through a lower oil passage a12 provided in the lower flow distribution disk 1 and a lower connecting oil passage a17 provided in the lower pump housing 16. The lower flow distribution waist-shaped port b15 is also communicated with the middle oil passage b23 through a lower oil passage b13 provided in the lower flow distribution disk 1 and a lower connecting oil passage b18 provided in the lower pump housing 16. In this embodiment, there are two lower flow distribution waist-shaped ports a14 on the upper surface of the lower flow distribution disk 1 and they are oppositely arranged, and the two lower flow distribution waist-shaped ports a14 respectively communicate with two variable volume chambers on the starting side of meshing of the lower pump housing 16. There are two lower flow distribution waist-shaped ports b15 on the upper surface of the lower flow distribution disk 1 and they are oppositely arranged, and the two lower flow distribution waist-shaped ports b15 respectively communicate with two variable volume chambers on the disengaging side of meshing of the lower pump housing 16.

[0060] Regarding the upper flow distribution disk 3, as Figure 7-8As shown in the figure, in order to increase the flow rate of the oil fluid, upper oil distribution waist-shaped port a34 communicating with the variable volume chamber on the starting side of the engagement with the upper pump housing 36 and upper oil distribution waist-shaped port b35 communicating with the variable volume chamber on the disengaging side of the engagement with the upper pump housing 36 are provided on the lower surface of the upper oil distribution disk 3. The upper oil distribution waist-shaped port a34 and the upper oil distribution waist-shaped port b35 are arranged opposite to each other. The upper oil distribution waist-shaped port a34 is also connected to the middle oil passage a22 through the upper oil passage a32 provided in the upper oil distribution disk 3 and the upper communication oil passage a37 provided in the upper pump housing 36. The upper oil distribution waist-shaped port b35 is also connected to the middle oil passage b23 through the upper oil passage b33 provided in the upper oil distribution disk 3 and the upper communication oil passage b38 provided in the upper pump housing 36. In this embodiment, there are two upper oil distribution waist-shaped ports a34 on the lower surface of the upper oil distribution disk 3 and they are arranged opposite to each other. The two upper oil distribution waist-shaped ports a34 are respectively connected to the two variable volume chambers on the starting side of the engagement with the upper pump housing 36. There are two upper oil distribution waist-shaped ports b35 on the lower surface of the upper oil distribution disk 3 and they are arranged opposite to each other. The two upper oil distribution waist-shaped ports b35 are respectively connected to the two variable volume chambers on the disengaging side of the engagement with the upper pump housing 36.

[0061] When the driving shaft gear 4 starts to rotate, the oil port a26 on the starting side of the engagement between the driving shaft gear 4 and the driven shaft gear 5 will serve as the oil discharge port, and together with the middle oil passage a22, the middle oil distribution waist-shaped port a24, the lower communication oil passage a17, the lower oil passage a12, the lower oil distribution waist-shaped port a14, the upper communication oil passage a37, the upper oil passage a32, and the upper oil distribution waist-shaped port a34, they form the oil discharge chamber of the pump. The oil port b27 on the disengaging side of the engagement between the driving shaft gear 4 and the driven shaft gear 5 will serve as the oil inlet, and together with the middle oil passage b23, the middle oil distribution waist-shaped port b25, the lower communication oil passage b18, the lower oil passage b13, the lower oil distribution waist-shaped port b15, the upper communication oil passage b38, the upper oil passage b33, and the upper oil distribution waist-shaped port b35, they form the oil inlet chamber of the pump.

[0062] Moreover, the connection points between the lower oil passage a12 and the lower communication oil passage a17, between the lower communication oil passage a17 and the middle oil passage a22, between the lower oil passage b13 and the lower communication oil passage b18, and between the lower communication oil passage b18 and the middle oil passage b23 are all on the end face of the lower pump housing 16. In order to prevent the oil fluid from leaking between the lower oil passage a12 and the lower communication oil passage a17, between the lower communication oil passage a17 and the middle oil passage a22, between the lower oil passage b13 and the lower communication oil passage b18, and between the lower communication oil passage b18 and the middle oil passage b23, in this embodiment, flow path sealing rings 7 are provided along the joints at the connection points between the lower oil passage a12 and the lower communication oil passage a17, between the lower communication oil passage a17 and the middle oil passage a22, between the lower oil passage b13 and the lower communication oil passage b18, and between the lower communication oil passage b18 and the middle oil passage b23. In order to install the flow path sealing rings 7, sealing ring installation grooves are provided on the end face of the lower pump housing 16, the upper end face of the lower oil distribution disk 1, and the lower end face of the middle oil distribution disk 2.

[0063] At the connection between the upper oil passage a32 and the upper connecting oil passage a37, at the connection between the upper connecting oil passage a37 and the middle oil passage a22, at the connection between the upper oil passage b33 and the upper connecting oil passage b38, and at the connection between the upper connecting oil passage b38 and the middle oil passage b23, they are all located on the end face of the upper pump housing 36. To prevent oil leakage between the upper oil passage a32 and the upper connecting oil passage a37, between the upper connecting oil passage a37 and the middle oil passage a22, between the upper oil passage b33 and the upper connecting oil passage b38, and between the upper connecting oil passage b38 and the middle oil passage b23 during oil transportation, in this embodiment, at the connection between the upper oil passage a32 and the upper connecting oil passage a37, at the connection between the upper connecting oil passage a37 and the middle oil passage a22, at the connection between the upper oil passage b33 and the upper connecting oil passage b38, and at the connection between the upper connecting oil passage b38 and the middle oil passage b23, there are all flow path sealing rings 7 arranged along the joints. To install the flow path sealing rings 7, there are sealing ring installation grooves on the end face of the upper pump housing 36, the upper end face of the upper distribution plate 3, and the upper end face of the middle distribution plate 2.

[0064] In this embodiment, to further prevent oil leakage, there are edge sealing rings 8 arranged along the edges of the contact surfaces between the lower distribution plate 1 and the lower pump housing 16, between the lower pump housing 16 and the middle distribution plate 2, between the middle distribution plate 2 and the upper pump housing 36, and between the upper pump housing 36 and the upper distribution plate 3.

[0065] In addition, regarding the installation of the driving shaft gear 4 and the driven shaft gear, there are two lower gear shaft installation holes 11 on the upper surface of the lower distribution plate 1 for installing the driving shaft gear 4 and the driven shaft gear 5, there are two middle gear shaft installation holes 21 on the middle distribution plate 2 for installing the driving shaft gear 4 and the driven shaft gear 5, and there are two upper gear shaft installation holes 31 on the lower surface of the upper distribution plate 3 for installing the driving shaft gear 4 and the driven shaft gear 5. At the same time, to enable the driving shaft gear 4 and the driven shaft gear 5 to rotate smoothly, there are bearings 6 for the rotational installation of the gear shafts of the driving shaft gear 4 and the driven shaft gear 5 in the lower gear shaft installation holes 11, the middle gear shaft installation holes 21, and the upper gear shaft installation holes 31.

[0066] In this embodiment, in order to connect the gear shaft of the driving shaft gear 4 to the driving device, the upper gear shaft mounting hole 31 and the middle gear shaft mounting hole 21 for mounting the driving shaft gear 4 are both through holes. The gear shaft at the upper part of the driving shaft gear 4 in the upper pump housing 36 passes through the upper gear shaft mounting hole 31 and is connected to the driving device. At the same time, an external spline is provided at the lower part of the driving shaft gear 4 in the upper pump housing 36, and an internal spline is provided at the upper part of the driving shaft gear 4 in the lower pump housing 16. The lower part of the driving shaft gear 4 in the upper pump housing 36 and the upper part of the driving shaft gear 4 in the lower pump housing 16 are connected by an involute spline through the middle gear shaft mounting hole 21. Moreover, in order to prevent the oil from leaking from the upper gear shaft mounting hole 31, a retaining ring 41 and a sealing leather cup 42 sleeved on the gear shaft of the driving shaft gear 4 are sequentially provided from top to bottom at the upper part of the upper gear shaft mounting hole 31.

[0067] It should be noted that:

[0068] The lower distribution disk 1, the lower pump housing 16, the middle distribution disk 2, the upper pump housing 36 and the upper distribution disk 3 are fixedly connected by two screws vertically penetrating through each component and two positioning pins vertically penetrating through each component. For this purpose, positioning pin holes 9 and threaded holes 91 are provided on the lower distribution disk 1, the lower pump housing 16, the middle distribution disk 2, the upper pump housing 36 and the upper distribution disk 3. In this embodiment, the setting positions of the positioning pin holes 9 and the threaded holes 91 are as Figure 1-8 shown.

[0069] Regarding the specific operation of this device, in combination with Figure 9-12 , taking the lower distribution disk 1 as an example, the working principle of the self-boosting gear pump to achieve oil inlet and oil discharge twice for each rotation of one tooth is described as follows:

[0070] When the driving shaft gear 4 rotates counterclockwise continuously, the oil port b27 will become the oil inlet port, and the oil port a26 will become the oil discharge port. Define the position where the tip of the driving shaft gear 4, the root of the driven shaft gear 5 coincide with the connecting line of the two rotation centers as the initial critical state - as Figure 9 shown. Since the contact ratio of the two gears is greater than 1, at least two meshing lines will be generated between the two gears, thus forming a variable volume chamber I as Figure 9 shown. The variable volume chamber I is composed of a closed chamber formed by the involute tooth surface of the driving shaft gear 4, the root circle of the driven shaft gear 5, the end face of the middle distribution disk 2 and the end face of the lower distribution disk 1. At this time, the variable volume chamber I is in the maximum compression state, the pressure of the squeezed oil is the highest, and the two lower distribution waist-shaped ports b15 communicating with the oil inlet chamber and the two lower distribution waist-shaped ports a14 communicating with the oil discharge chamber are both blocked by the gear end faces.

[0071] Then, the driving shaft gear 4 rotates from the initial critical position to 1 / 4 of a tooth, that is: from Figure 8 — Figure 9The process. During this process, a new variable volume chamber two is formed. Variable volume chamber two is composed of the closed chamber jointly formed by the top circle of the driven shaft gear 5, the involute tooth surface of the driving shaft gear 4, the end face of the middle distribution plate 2, and the end face of the lower distribution plate 1. During this process, the volume of variable volume chamber one gradually increases, the oil pressure gradually decreases, and the oil will replenish variable volume chamber one through one of the lower distribution waist-shaped ports b15 communicating with the oil inlet chamber. The volume of variable volume chamber one becomes larger and larger until the pair of gears disengage. At this time, the oil sucked from the oil inlet chamber enters the gap between the "8"-shaped installation chamber 51 and the top circle of the gear teeth through the disengaged gears, and as the gears rotate, it is carried to the side where the gears gradually engage, completing self-boost. During this process, the volume of variable volume chamber two gradually decreases, the oil is squeezed, the pressure gradually increases, and one of the lower distribution waist-shaped ports a14 communicating with the oil discharge chamber is not blocked by the gear tooth profile after rotation, and the high-pressure oil will flow to the oil discharge chamber through this lower distribution waist-shaped port a14. During this process, the other lower distribution waist-shaped port b15 and the other lower distribution waist-shaped port a14 are completely blocked by the gear end face, thus completing one oil suction and oil discharge.

[0072] Next, the driving shaft gear 4 continues to rotate from 1 / 4 tooth to half a tooth, that is: from Figure 9 — Figure 10 The process. During this process, the volume of variable volume chamber two will gradually decrease, the pressure inside the chamber gradually increases, and the oil continues to be discharged to the oil discharge chamber through the aforementioned lower distribution waist-shaped port a14. As the gears rotate, the aforementioned lower distribution waist-shaped port b15 communicating with the oil suction chamber will gradually be blocked by the end face of the driven shaft gear 5 until it is completely blocked. Similarly, the unblocked part of the aforementioned lower distribution waist-shaped port a14 will gradually decrease until it is completely blocked by the end face of the driving shaft gear 4. At this time, the volume of variable volume chamber two becomes the smallest, and variable volume chamber one disappears due to the gears gradually disengaging. During this process, the other lower distribution waist-shaped port b15 and the other lower distribution waist-shaped port a14 continue to be completely blocked. When the volume of variable volume chamber two is the smallest, the two lower distribution waist-shaped ports b15 communicating with the oil inlet chamber and the two lower distribution waist-shaped ports a14 communicating with the oil discharge chamber are all blocked by the gear end faces.

[0073] Finally, the driving shaft gear 4 continues to rotate from half a tooth to 3 / 4 tooth, that is: from Figure 10 — Figure 11During this process, the volume of the second variable chamber will gradually increase, the oil pressure in the chamber will gradually decrease, and the uncovered part of one of the lower porting waist-shaped ports b15 communicating with the oil inlet chamber will gradually increase. Oil will replenish the second variable chamber through this lower porting waist-shaped port b15 until the second variable chamber disappears due to the complete disengagement of the gears during rotation. The oil sucked from the oil inlet chamber enters the gap between the "8"-shaped mounting chamber 51 and the addendum circle of the gear through the disengaged gears, and as the gears rotate, it is carried to the side where the gears gradually engage, completing self-boost. During this process, the third variable chamber will be re-formed. The third variable chamber is composed of a closed chamber jointly formed by the addendum circle of the driving shaft gear 4, the involute tooth surface of the driven shaft gear 5, the end face of the middle porting disk 2, and the end face of the lower porting disk 1. As the gears rotate, the volume of the third variable chamber gradually decreases, the oil pressure will gradually increase, and the uncovered part of one of the lower porting waist-shaped ports a14 communicating with the oil discharge chamber will gradually increase. The high-pressure oil is discharged to the oil discharge chamber through the lower porting waist-shaped port a14. During this process, the other lower porting waist-shaped port b15 and the other lower porting waist-shaped port a14 are completely blocked by the gear end face, thus completing one oil suction and one oil discharge again.

[0074] Meanwhile, the working principles of the middle porting waist-shaped ports a24 and b25 in the middle porting disk 2, and the upper porting waist-shaped ports a34 and b35 in the upper porting disk 3 are the same as those of the lower porting waist-shaped ports a14 and b15 in the lower porting disk 1, and will not be elaborated here. By repeating the above steps, oil discharge can be achieved through the lower porting waist-shaped port a14, the middle porting waist-shaped port a24, and the upper porting waist-shaped port a34 communicating with the oil discharge chamber, while oil replenishment for the variable chamber can be achieved through the lower porting waist-shaped port b15, the middle porting waist-shaped port b25, and the upper porting waist-shaped port b35 communicating with the oil inlet chamber. For each tooth the meshing gears rotate through, 2 oil suction operations and 2 oil discharge operations will be achieved.

[0075] Similarly, when the driving shaft gear rotates clockwise continuously, the working principle of the gear pump is the same as above and will not be elaborated here. Therefore, this gear pump can also freely switch the oil discharge and oil suction directions according to the rotation direction of the driving shaft gear 4, enabling the gear pump to have a two-way function.

[0076] Regarding how to achieve low torque fluctuation of the self-boost gear pump, combined with Figure 13 and Figure 16 , the specific principle is described as follows:

[0077] When the driving shaft gear 4 rotates clockwise, Figure 13-14 shows the change in the force arm of the torque during the process of the driving gear of the existing self-boost gear pump rotating half a tooth. Figure 15-16The figure shows the change in the torque arm during the rotation of the driving shaft gear 4 of a self - pressurizing gear pump capable of achieving low torque fluctuation provided by an embodiment of the present invention by half a tooth. Taking the torque arm change in the above - mentioned two processes as an example, the principle of achieving low torque fluctuation is compared and explained.

[0078] As Figure 13-14 shown, during the process of the driving gear of the existing self - pressurizing gear pump rotating by half a tooth from the illustrated position, that is, during the process of, when the driving gear rotates clockwise, since only one set of gears is meshing, only one of the two flow - distribution kidney - shaped ports on the same side communicating with the oil inlet cavity will participate in the work, and the two flow - distribution kidney - shaped ports will alternately participate in oil discharge. Similarly, only one of the two flow - distribution kidney - shaped ports on the same side communicating with the oil discharge cavity will participate in the work, and the two flow - distribution kidney - shaped ports will alternately participate in oil suction. This will inevitably cause the torque arm formed by the gear meshing point relative to the rotation center of the driving gear to change from L to L', and the torque arm of the input shaft will change periodically between L and L', thus showing a periodic fluctuation in the amplitude of the input - shaft torque.

[0079] As Figure 15-16 shown, during the process of the driving shaft gear 4 of a self - pressurizing gear pump with low torque fluctuation rotating by half a tooth from the illustrated position, when the driving shaft gear 4 rotates clockwise, due to the upper and lower two sets of meshing gear sets installed with a half - tooth stagger, during the operation of the gear pump, at a certain time, the variable - volume cavities communicated with the middle flow - distribution kidney - shaped port a24 on the upper surface of the middle flow - distribution disk 2 and the variable - volume cavities communicated with the middle flow - distribution kidney - shaped port a24 on the lower surface of the middle flow - distribution disk 2 are symmetric about the left and right, and will discharge oil simultaneously; the variable - volume cavities communicated with the middle flow - distribution kidney - shaped port b25 on the upper surface of the middle flow - distribution disk 2 and the variable - volume cavities communicated with the middle flow - distribution kidney - shaped port b25 on the lower surface of the middle flow - distribution disk 2 are symmetric about the left and right, and will suck oil simultaneously.

[0080] During this process, for the first meshing gear set, the torque arm formed by the gear meshing point relative to the rotation center of the driving gear will change from L1 to L1', and the arm L will change periodically between L1 and L1' as the gear rotates; for the second meshing gear set, the torque arm formed by the gear meshing point relative to the rotation center of the driving gear will change from L2 to L2', and the arm L will change periodically between L2 and L2' as the gear rotates. Thus, relative to the input shaft, its average torque arm will change periodically between (L1 + L1') / 2 and (L2 + L2') / 2.

[0081] Therefore, the amplitude of the input shaft torque fluctuation of the self-boosting gear pump with low torque fluctuation proposed by the present invention will be significantly smaller than that of the existing self-boosting gear pump, so that the low torque fluctuation of the self-boosting gear pump can be achieved. Similarly, when the driving shaft gear 4 rotates counterclockwise, the principle of the input shaft torque fluctuation change is the same as above, and will not be elaborated here.

[0082] The present invention has been described above in conjunction with the best embodiments, but the present invention is not limited to the disclosed embodiments above, but should cover various modifications and equivalent combinations made according to the essence of the present invention.

Claims

1. A self-boosting gear pump with low torque fluctuation, comprising a lower distribution plate (1), a lower pump housing (16), a middle distribution plate (2), an upper pump housing (36) and an upper distribution plate (3) which are sequentially overlapped from bottom to top, characterized in that, The lower pump housing (16) and the upper pump housing (36) are both provided with an "8"-shaped installation cavity (51). Two of the "8"-shaped installation cavities (51) are arranged vertically opposite to each other, and a driving shaft gear (4) and a driven shaft gear (5) that mesh with involute gears are horizontally installed in both of the "8"-shaped installation cavities (51). Between the two driving shaft gears (4) and between the two driven shaft gears (5), they are arranged coaxially, in the same direction, and rotate synchronously. Moreover, the meshing teeth of the driving shaft gear (4) and the driven shaft gear (5) located in the lower pump housing (16) are installed with a half-tooth offset from the meshing teeth of the driving shaft gear (4) and the driven shaft gear (5) located in the upper pump housing (36). On the lower surface and the upper surface of the middle distribution plate (2), there are respectively a middle distribution waist-shaped port a (24) communicating with the variable volume cavity on the starting side of meshing and a middle distribution waist-shaped port b (25) communicating with the variable volume cavity on the disengaging side of meshing. Inside the middle distribution plate (2), there is a middle oil passage a (22) located on the starting side of meshing and a middle oil passage b (23) located on the disengaging side of meshing. One end of the middle oil passage a (22) communicates with an oil port a (26) provided on the outer side wall of the middle distribution plate (2), and the other end communicates with the middle distribution waist-shaped port a (24). One end of the middle oil passage b (23) communicates with an oil port b (27) provided on the outer side wall of the middle distribution plate (2), and the other end communicates with the middle distribution waist-shaped port b (25).

2. The self - pressurizing gear pump with low torque fluctuation according to claim 1, wherein, There are two middle distribution waist-shaped ports a (24) on the lower surface of the middle distribution plate (2) and they are arranged relatively. The two middle distribution waist-shaped ports a (24) respectively communicate with the two variable volume cavities on the starting side of meshing of the lower pump housing (16). There are two middle distribution waist-shaped ports b (25) on the lower surface of the middle distribution plate (2) and they are arranged relatively. The two middle distribution waist-shaped ports b (25) respectively communicate with the two variable volume cavities on the disengaging side of meshing of the lower pump housing (16). There are two middle distribution waist-shaped ports a (24) on the upper surface of the middle distribution plate (2) and they are arranged relatively. The two middle distribution waist-shaped ports a (24) respectively communicate with the two variable volume cavities on the starting side of meshing of the upper pump housing (36). There are two middle distribution waist-shaped ports b (25) on the upper surface of the middle distribution plate (2) and they are arranged relatively. The two middle distribution waist-shaped ports b (25) respectively communicate with the two variable volume cavities on the disengaging side of meshing of the upper pump housing (36).

3. The self-boosting gear pump with low torque fluctuation according to claim 1 or 2, characterized in that, On the upper surface of the lower distribution plate (1), there is a lower distribution waist-shaped port a (14) communicating with the variable volume cavity on the starting side of meshing of the lower pump housing (16) and a lower distribution waist-shaped port b (15) communicating with the variable volume cavity on the disengaging side of meshing of the lower pump housing (16). The lower distribution waist-shaped port a (14) also communicates with the middle oil passage a (22) through a lower oil passage a (12) provided in the lower distribution plate (1) and a lower connecting oil passage a (17) provided in the lower pump housing (16). The lower distribution waist-shaped port b (15) also communicates with the middle oil passage b (23) through a lower oil passage b (13) provided in the lower distribution plate (1) and a lower connecting oil passage b (18) provided in the lower pump housing (16). The lower surface of the upper flow distribution disc (3) is provided with an upper flow distribution waist-shaped port a (34) communicating with the variable volume chamber on the starting side of the engagement with the upper pump housing (36), and an upper flow distribution waist-shaped port b (35) communicating with the variable volume chamber on the disengaging side of the engagement with the upper pump housing (36). The upper flow distribution waist-shaped port a (34) is also communicated with the middle oil passage a (22) through an upper oil passage a (32) provided in the upper flow distribution disc (3) and an upper communication oil passage a (37) provided in the upper pump housing (36). The upper flow distribution waist-shaped port b (35) is also communicated with the middle oil passage b (23) through an upper oil passage b (33) provided in the upper flow distribution disc (3) and an upper communication oil passage b (38) provided in the upper pump housing (36).

4. The self-boosting gear pump with low torque fluctuation according to claim 3, characterized in that, There are two lower flow distribution waist-shaped ports a (14) on the upper surface of the lower flow distribution disc (1), which are arranged oppositely. The two lower flow distribution waist-shaped ports a (14) are respectively communicated with the two variable volume chambers on the starting side of the engagement with the lower pump housing (16). There are two lower flow distribution waist-shaped ports b (15) on the upper surface of the lower flow distribution disc (1), which are arranged oppositely. The two lower flow distribution waist-shaped ports b (15) are respectively communicated with the two variable volume chambers on the disengaging side of the engagement with the lower pump housing (16).

5. The self-boosting gear pump with low torque fluctuation according to claim 4, wherein There are two upper flow distribution waist-shaped ports a (34) on the lower surface of the upper flow distribution disc (3), which are arranged oppositely. The two upper flow distribution waist-shaped ports a (34) are respectively communicated with the two variable volume chambers on the starting side of the engagement with the upper pump housing (36). There are two upper flow distribution waist-shaped ports b (35) on the lower surface of the upper flow distribution disc (3), which are arranged oppositely. The two upper flow distribution waist-shaped ports b (35) are respectively communicated with the two variable volume chambers on the disengaging side of the engagement with the upper pump housing (36).

6. The self - pressurizing gear pump with low torque fluctuation according to claim 5, characterized in that, At the connection of the lower oil passage a (12) and the lower communication oil passage a (17), at the connection of the lower communication oil passage a (17) and the middle oil passage a (22), at the connection of the lower oil passage b (13) and the lower communication oil passage b (18), at the connection of the lower communication oil passage b (18) and the middle oil passage b (23), at the connection of the upper oil passage a (32) and the upper communication oil passage a (37), at the connection of the upper communication oil passage a (37) and the middle oil passage a (22), at the connection of the upper oil passage b (33) and the upper communication oil passage b (38), and at the connection of the upper communication oil passage b (38) and the middle oil passage b (23), there are flow passage sealing rings (7) arranged along the joints.

7. The self-boosting gear pump with low torque fluctuation according to claim 1, characterized in that, The upper surface of the lower flow distribution disc (1) is provided with two lower gear shaft mounting holes (11) for mounting the driving shaft gear (4) and the driven shaft gear (5). The middle flow distribution disc (2) is provided with two middle gear shaft mounting holes (21) for mounting the driving shaft gear (4) and the driven shaft gear (5). The lower surface of the upper flow distribution disc (3) is provided with two upper gear shaft mounting holes (31) for mounting the driving shaft gear (4) and the driven shaft gear (5). Bearings (6) for the rotational mounting of the gear shafts of the driving shaft gear (4) and the driven shaft gear (5) are provided in the lower gear shaft mounting holes (11), the middle gear shaft mounting holes (21), and the upper gear shaft mounting holes (31).

8. The self-boosting gear pump with low torque fluctuation according to claim 7, characterized in that, The upper gear shaft mounting hole (31) and the middle gear shaft mounting hole (21) for mounting the driving shaft gear (4) are both through holes. A retaining ring (41) and a sealing leather cup (42) sleeved on the gear shaft of the driving shaft gear (4) are successively arranged from top to bottom in the upper part of the upper gear shaft mounting hole (31).

9. The self - pressurizing gear pump with low torque fluctuation according to claim 1, wherein, Edge sealing rings (8) are arranged along the edges of the contact surfaces between the lower distribution plate (1) and the lower pump housing (16), between the lower pump housing (16) and the middle distribution plate (2), between the middle distribution plate (2) and the upper pump housing (36), and between the upper pump housing (36) and the upper distribution plate (3).

10. The self - pressurizing gear pump with low torque fluctuation according to claim 1, characterized in that, Positioning pin holes (9) and threaded holes (91) are provided on the lower distribution plate (1), the lower pump housing (16), the middle distribution plate (2), the upper pump housing (36), and the upper distribution plate (3).

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