Bidirectional hydraulic gear pump

Abstract

The invention relates to the field of gear pumps, in particular to a bidirectional hydraulic gear pump. The bidirectional hydraulic gear pump comprises a pump body, a front cover and a rear cover, the pump body, the front cover and the rear cover define a cylindrical sealed space, a gear shaft, an inner gear ring, a crescent main plate, a crescent auxiliary plate, a side plate and a positioning rod are arranged in the cylindrical sealed space, and the crescent main plate is provided with six special-shaped grooves which are symmetrically distributed left and right. The special-shaped groove comprises two flat spring exclusive grooves and four composite function grooves, the two flat spring exclusive grooves are formed in the outermost side, flat springs are arranged in the flat spring exclusive grooves, flat springs and sealing rods are arranged in the composite function grooves, and the flat spring exclusive grooves are formed in the outermost side.

Description

TECHNICAL FIELD

[0001] The application relates to the field of gear pumps, in particular to a bidirectional hydraulic gear pump. BACKGROUND

[0002] The hydraulic gear pump is a common hydraulic element, which is mainly used for converting mechanical energy into hydraulic energy and conveying liquid through the meshing of gears to provide power for the hydraulic system. The hydraulic gear pump is widely used in various industrial mechanical equipment, such as injection molding machines, die casting machines and machine tools, for providing hydraulic power. The hydraulic gear pump is also used in the power steering system and brake system of an automobile.

[0003] In the actual use of customers, higher use requirements are put forward for the gear pump, and the bidirectional gear pump can better meet the actual use requirements of customers.

[0004] The prior art CN111089050A provides a bidirectional gear motor pump, which has the problem of slow pressure during starting. SUMMARY

[0005] The application aims to provide a bidirectional hydraulic gear pump, and the specific scheme is as follows:

[0006] A bidirectional hydraulic gear pump comprises a pump body, a front cover and a rear cover, which surround a cylindrical sealing space, wherein a gear shaft, an inner gear ring, a crescent main plate, a crescent auxiliary plate, a side plate and a positioning rod are arranged in the cylindrical sealing space, the crescent main plate is provided with six symmetrical special-shaped grooves, the special-shaped grooves comprise two leaf spring special grooves and four composite function grooves, the two leaf spring special grooves are arranged at the outermost sides, leaf springs are arranged in the leaf spring special grooves, and leaf springs and sealing rods are arranged in the composite function grooves.

[0007] The crescent auxiliary plate is provided with an oil passage, and the oil passage is in communication with at least one group of composite function grooves.

[0008] The crescent auxiliary plate is provided with a trapezoidal groove, the positioning rod comprises a trapezoidal rod part and a trapezoidal rod cylindrical part, and the trapezoidal groove and the trapezoidal rod part are matched.

[0009] The trapezoidal groove and the trapezoidal rod part have a gap one and a gap two.

[0010] The front cover comprises a pump body sealing surface, the pump body sealing surface is symmetrically provided with an oil port A and an oil port B, and the pump body sealing surface is symmetrically provided with a back pressure groove A and a back pressure groove B.

[0011] The phase angles of the back pressure groove A and the back pressure groove B are 25-36°.

[0012] The phase angle of the back pressure groove A and the back pressure groove B is 28°, and the angle between the adjacent two oil holes on the inner gear ring and the center line of the inner gear ring is 25°, and the angle with the starting point of the third oil hole is 36°.

[0013] The side plate comprises a side plate gear shaft hole, a side plate oil guide groove one, a side plate oil guide groove two, a side plate through hole one, a side plate through hole two, a side plate through hole three, a side plate through hole four, a side plate through hole five and a side plate through hole six, and the side plate through hole one and the side plate through hole six are symmetrically arranged, the side plate through hole three and the side plate through hole four are symmetrically arranged, and the side plate through hole two and the side plate through hole five are symmetrically arranged; the front cover comprises a front cover special-shaped groove one and a front cover special-shaped groove two, the rear cover comprises a rear cover special-shaped groove one and a rear cover special-shaped groove two, the positions of the side plate through hole two and the side plate through hole three are matched with the positions of the front cover special-shaped groove two and the rear cover special-shaped groove two, and the positions of the side plate through hole four and the side plate through hole five are matched with the positions of the front cover special-shaped groove four and the rear cover special-shaped groove five.

[0014] The side plate through hole two extends a side plate eyebrow groove two, the side plate through hole five extends a side plate eyebrow groove three, the side plate eyebrow groove two and the side plate eyebrow groove three jointly point to the gap between the gear shaft and the crescent main plate, the side plate through hole one extends a side plate eyebrow groove one, the side plate through hole six extends a side plate eyebrow groove four, and the side plate eyebrow groove one and the side plate eyebrow groove four jointly point to the gap between the inner gear ring and the crescent auxiliary plate.

[0015] The side plate and the front cover and the rear cover are both provided with special-shaped O-rings and special-shaped retainer rings, and the shapes of the special-shaped O-rings and the special-shaped retainer rings are matched with the front cover special-shaped groove one, the front cover special-shaped groove two, the rear cover special-shaped groove one and the rear cover special-shaped groove two.

[0016] The crescent main plate of the application comprises 6 special-shaped grooves, and the outermost 2 are special grooves for leaf springs, and the remaining 4 middle composite function grooves are the core points of the application. The leaf springs are installed in the special grooves for leaf springs, and through the compression pre-tightening force when installed, the crescent main plate and the crescent secondary plate are pushed open to both sides, so that the inner arc surface of the crescent main plate is tightly attached to the gear tooth top circle of the gear shaft, and the outer arc surface of the crescent secondary plate is tightly attached to the tooth top circle of the inner gear ring, so that the gear pump realizes the static sealing effect of the crescent gear ring in the non-running state. The realization of this effect can make the gear pump suck in oil liquid faster when starting, reach the target pressure, and the number of leaf springs will affect the static sealing effect, and more leaf springs will make the pressure building process shorter. When the gear pump is running, the output port will reach a high pressure value, at this time the pre-tightening force of the leaf spring alone cannot press the crescent main plate and the crescent secondary plate to the tooth top circle of the gear ring, so high-pressure oil needs to be introduced between the crescent main plate and the crescent secondary plate to make the crescent main plate and the crescent secondary plate continue to fit the tooth top circle of the gear ring during the running of the gear pump, and realize the sealing effect. The reason why the application does not set a plastic rod at the special groove for leaf spring is to leave a gap so that high-pressure oil can enter the special groove for leaf spring, and then the oil pressure of the special groove for leaf spring is equal to the pressure of the output port; similarly, the function of the oil groove on the crescent secondary plate is to guide the oil in the gradually increasing pressure process between the inner gear ring teeth into the composite function groove, so the oil pressure of the composite function groove is lower than the pressure of the output port. The function of the plastic rod is to seal and prevent high-pressure oil from leaking; the two plastic rods are to prevent high-pressure oil from leaking from the output port to the high-pressure transition area and the low-pressure area (the outer plastic rod), and to prevent high-pressure oil from leaking from the high-pressure transition area to the low-pressure area (the inner plastic rod). The two plastic rods greatly isolate the communication possibility between the high-pressure area and the low-pressure area.

[0017] The side plate is provided with side plate through holes two, three, four and five, and pressure oil is introduced into the special-shaped grooves (front cover special-shaped groove one, front cover special-shaped groove two, rear cover special-shaped groove one and rear cover special-shaped groove two) surrounded by special-shaped sealing rings on the front and rear covers, that is, the pressure values on both sides of the side plate in the high-pressure area are consistent, and the area of the special-shaped grooves on the front and rear covers is larger than the area of the high-pressure area on the other side of the side plate (that is, the gear ring surface, the gear ring occupies part of the area), so during the running of the gear pump, the hydraulic force acting on the side plate is directed to the gear ring direction, and the side plate is pressed towards the gear ring to provide axial sealing for the gear pump. The side plate eyebrow groove two and the side plate eyebrow groove three extend to the gap between the gear shaft and the crescent main plate, and during the running of the gear pump, the high-pressure oil introduced from the side plate through hole one and the side plate through hole five will gradually pressurize the hydraulic oil between the gear teeth until the pressure value reaches the pressure value of the output port; similarly, the side plate eyebrow groove one and the side plate eyebrow groove four have the same function, because the oil pressure between the teeth does not change suddenly, so the noise value during the running of the gear pump is greatly reduced.

[0018] The phase angle of the sealing area between the two symmetrical back pressure grooves (back pressure groove A and back pressure groove B) on the pump body will affect the volumetric efficiency of the gear pump during operation, which is obviously embodied in the experimental results. The phase angle should be greater than the angle formed by two adjacent through holes on the inner ring gear and less than the angle formed by three through holes. When the phase angle is less than the angle formed by two adjacent through holes on the inner ring gear, i.e. less than 25°, the volumetric efficiency is 90.23% at 1500 rpm and 25 MPa pressure difference, which does not meet the factory standard. The main reason is that the smaller phase angle leads to insufficient sealing arc, and a part of the high-pressure oil is taken away from the high-pressure area by the inner ring gear during the operation of the gear pump, causing internal leakage. When the phase angle is greater than the angle formed by three through holes, it will cause serious oil entrapment phenomenon, and the high-pressure oil is trapped in the channel of the inner ring gear for a long time, causing damage to the sealing area of the inner ring gear and the pump body. Therefore, the design of the phase angle of the sealing area on the pump body should be appropriate, i.e. 25-36°, and 28° is the most appropriate angle in this range after multiple tests. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 Structure diagram of a bidirectional hydraulic gear pump of the present application Figure 1 ;

[0020] Figure 2 Structure diagram of a bidirectional hydraulic gear pump of the present application Figure 2 ;

[0021] Figure 3 Structure diagram of a bidirectional hydraulic gear pump of the present application Figure 3 ;

[0022] Figure 4 Structure diagram of a bidirectional hydraulic gear pump of the present application Figure 1 ;

[0023] Figure 5 Structure diagram of a bidirectional hydraulic gear pump of the present application Figure 2 ;

[0024] Figure 6 Structure diagram of a bidirectional hydraulic gear pump of the present application Figure 3 ;

[0025] Figure 7 Structure diagram of a bidirectional hydraulic gear pump of the present application Figure 4 ;

[0026] Figure 8 Structure diagram of a bidirectional hydraulic gear pump of the present application Figure 5 ;

[0027] Figure 9Part structure diagram of a bidirectional hydraulic gear pump of the present application Figure 6 ;

[0028] Figure 10 Part structure diagram of a bidirectional hydraulic gear pump of the present application Figure 7 ;

[0029] Figure 11 Part structure diagram of a bidirectional hydraulic gear pump of the present application Figure 8 ;

[0030] Figure 12 Part structure diagram of a bidirectional hydraulic gear pump of the present application Figure 9 ;

[0031] Figure 13 Part structure diagram of a bidirectional hydraulic gear pump of the present application Figure 10 ;

[0032] Figure 14 Part structure diagram of a bidirectional hydraulic gear pump of the present application Figure 10 ;

[0033] Figure 15 Part structure diagram of a bidirectional hydraulic gear pump of the present application Figure 10 ;

[0034] Figure 16 Part structure diagram of a bidirectional hydraulic gear pump of the present application Figure 10 ;

[0035] Figure 17 Test chart of low-speed (80 rpm) steady pressure test of Example 1

[0036] Figure 18 Test chart of low-speed steady pressure test of Example 1

[0037] Figure 19 Test chart of pressure-maintaining (5 MPa) rotation speed test of Example 1

[0038] Figure 20 Test chart of pressure-maintaining (10 MPa) rotation speed test of Example 1

[0039] Figure 21 Test chart of pressure-maintaining (15 MPa) rotation speed test of Example 1

[0040] Figure 22 Test chart of pressure-maintaining (17.5 MPa) rotation speed test of Example 1

[0041] Figure 23 Test chart of low-speed (80 rpm) steady pressure test of Example 2

[0042] Figure 24 Low speed steady pressure test plot for Example 2;

[0043] Figure 25 Hold pressure (5 MPa) speed experiment plot for Example 2;

[0044] Figure 26 Hold pressure (10 MPa) speed experiment plot for Example 2;

[0045] Figure 27 Hold pressure (15 MPa) speed experiment plot for Example 2;

[0046] Figure 28 Hold pressure (17.5 MPa) speed experiment plot for Example 2;

[0047] Figure 29 Low speed (80 rpm) steady pressure test plot for Example 3;

[0048] Figure 30 Low speed steady pressure test plot for Example 3;

[0049] Figure 31 Hold pressure (5 MPa) speed experiment plot for Example 3;

[0050] Figure 32 Hold pressure (10 MPa) speed experiment plot for Example 3;

[0051] Figure 33 Hold pressure (15 MPa) speed experiment plot for Example 3;

[0052] Figure 34 Hold pressure (17.5 MPa) speed experiment plot for Example 3;

[0053] Wherein the label: 1. Pump body; 1.1. Pump body outer drain; 1.2. Oil port A; 1.3. Back pressure tank A; 1.4. Back pressure tank B; 1.5. Oil port B; 1.6. Pump body sealing surface; 2. Inner ring; 2.1. Inner ring oil hole; 3. Crescent main plate; 3.1. Special-shaped groove one; 3.2. Special-shaped groove two; 3.3. Special-shaped groove three; 3.4. Trapezoidal groove; 3.5. Special-shaped groove four; 3.6. Special-shaped groove five; 3.7. Special-shaped groove six; 4. Positioning rod; 4.1. Positioning rod trapezoidal part; 4.2. Positioning rod cylindrical part; 5. Crescent sub-plate; 5.1. Oil groove; 6. Plastic rod; 7. Leaf spring; 8. Gear shaft; 9. Front cover; 9.1. Front cover special-shaped groove one; 9.2. Front cover oil groove; 9.3. Front cover special-shaped groove two; 9.4. Front cover oil seal space; 10. Special-shaped O-ring; 11. Special-shaped check ring; 12. Side plate; 12.1. Positioning rod through hole; 12.2. Side plate eyebrow groove one; 12.3. Side plate through hole one; 12.4. Side plate eyebrow groove two; 12.5. Side plate through hole two; 12.6. Side plate through hole three; 12.7. Side plate gear shaft hole; 12.8. Side plate through hole four; 12.9. Side plate through hole five; 12.10. Side plate eyebrow groove three; 12.11. Side plate through hole six; 12.12. Side plate eyebrow groove four; 12.13. Side plate oil guide groove one; 12.14. Side plate oil guide groove two; 13. Rear cover; 13.1. Rear cover outer drain hole; 13.2. Rear cover special-shaped groove one; 13.3. Rear cover oil groove; 13.4. Rear cover special-shaped groove two; 34.1. Gap one; 34.2. Gap two. DETAILED DESCRIPTION

[0054] Example 1

[0055] The following will be described in conjunction with Figures 1-13 :

[0056] Pump body 1, front cover 9, rear cover 13 (including rear cover outer drain hole 13.1) are connected together by hexagonal socket head cap screws, and the inside forms a cylindrical sealing space. The gear shaft 8 and the inner ring 2 are rotated by the motor, and in the rotating process, the gear shaft 8, the inner ring 2, the two side plates 12, the crescent main plate 3, the two crescent sub-plates 5 and the two positioning rods 4 divide the cylindrical internal space into three areas, which are low pressure area, outer drain area and high pressure area in turn according to the flow direction of the oil. The oil is first sucked by the oil suction port, and when the gear shaft 8 and the inner ring 2 rotate to the position of the positioning rod 4, the oil of the gear shaft 8 and the inner ring 2 is communicated with the oil of the outer drain area through the oil groove on the side plate 12, and after rotating through the oil groove area on the side plate 12, the gear shaft 8 and the inner ring 2 The tooth top circle and the inner and outer arc surface of the crescent main and sub-plate 5 form a seal, which isolates the high pressure area from the outer drain area. The oil between the teeth passes through the eyebrow groove on the side plate 12, and is continuously pressurized in the rotating process until the pressure reaches the rated pressure value, and the high pressure oil is extruded in the meshing process of the gear shaft 8 and the inner ring 2.

[0057] Oil flow direction (as shown below Figure 2

[0058] Side plate 12: Side plate hole two 12.5 / side plate hole three 12.6 and side plate hole four 12.8 / side plate hole five 12.9 connect front cover special-shaped slot one 9.1 / front cover special-shaped slot two 9.3 and rear cover special-shaped slot one 13.2 / rear cover special-shaped slot two 13.4, the through hole leads high pressure oil into the special-shaped slot of front cover and rear cover, the area of special-shaped slot of front cover and rear cover is larger than the area of high pressure zone of gear ring side, under the same high pressure, the direction of resultant force of side plate 12 points to the gear ring side, in the running process, side plate 12 is pressed to the gear ring end face, reducing internal leakage during operation; Positioning rod through hole 12.1 is used for placing positioning rod 4; Side plate gear shaft hole 12.7 is used for placing gear shaft 8. Side plate eyebrow slot two 12.4 and side plate eyebrow slot three 12.10 extend to the gap between gear shaft 8 and crescent main plate 3, during the operation of gear pump, the high pressure oil led out from side plate hole one 12.3 and side plate hole five 12.9 will gradually pressurize the hydraulic oil between gear teeth, until the pressure value reaches the pressure value of output port; Similarly, the function of side plate eyebrow slot one 12.2 (extended from side plate hole one 12.3) and side plate eyebrow slot four 12.12 (extended from side plate hole six 12.11) is the same, because the oil pressure between teeth is not sudden change, so the noise value during the operation of gear pump is greatly reduced.

[0059] ​The pump body 1 comprises a pump body outer oil leakage channel 1.1 and a pump body sealing surface 1.6, two oil ports A1.2 and oil port B1.5 are symmetrically arranged on the pump body sealing surface 1.6, the oil port A1.2 is a high-pressure oil outlet when the gear shaft 8 rotates clockwise, the oil port B1.5 is a high-pressure oil outlet when the gear shaft 8 rotates counterclockwise, the oil port A1.2 and the oil port B1.5 are not limited in direction, can be distributed left and right, can also be vertically distributed, and can also be connected to the special-shaped groove position from the rear cover. Two symmetrically arranged back pressure grooves A1.3 and back pressure groove B1.4, when the gear shaft rotates clockwise, the back pressure groove A1.3 is a high-pressure back pressure area, the pressure of the high-pressure oil will push to the inner ring gear, the size of the pressure is affected by the angle of the phase angle occupied by the oil channel, and the angle of the phase angle is not limited here. When rotating counterclockwise, the back pressure groove B1.4 is a high-pressure back pressure area. The two symmetrically arranged back pressure grooves are the focus of this patent application (especially the angle). The angle between the center line of the inner ring gear 2 and the two adjacent inner ring gear oil holes 2.1 is 25°, and the angle between the center line and the start point of the third oil hole is 36°, so the angle between the sealing area of the inner ring gear 2 and the center line of the pump body hole is 28°, which not only ensures the sealing of high-pressure oil when the gear ring is engaged, but also avoids the oil accumulation caused by excessive sealing area. The phase angle of the sealing area between the back pressure grooves (back pressure groove A1.3 and back pressure groove B1.4) will affect the volumetric efficiency of the gear pump during operation, which is obviously shown in the experimental results. The phase angle should be greater than the angle between the two adjacent holes on the inner ring gear and less than the angle between the three holes. The design of the phase angle of the sealing area on the pump body should be appropriate, 25-36°, and 28° is the most appropriate angle in this range (the embodiment is 28°).

[0060] The positioning rod 4 is divided into upper and lower parts, the upper positioning rod trapezoidal part 4.1 is embedded in the trapezoidal groove 3.4 of the crescent main plate 3 during assembly, and after embedding, there are two symmetrical gaps between the two parts, i.e. gap one 34.1 and gap two 34.2, which are used to ensure that the main plate can move in a small range according to the force during operation, realize real-time dynamic sealing of the high-pressure area during operation, and improve the volumetric efficiency.

[0061] There are six symmetrical special-shaped grooves on the outer circular surface of the crescent main plate 3, special-shaped groove one 3.1 / special-shaped groove six 3.7 are used to place the leaf spring 7 (i.e. leaf spring special groove); special-shaped groove two 3.2 / special-shaped groove three 3.3 / special-shaped groove four 3.5 / special-shaped groove five 3.6 are used to place the plastic rod 6 (i.e. sealing rod) and the leaf spring 7 (i.e. composite function groove); the symmetrical distribution of the six special-shaped grooves and the number and specific groove function design are the focus of this patent application.

[0062] Six special-shaped slots installed in the leaf spring 7, before the gear pump operation provides pre-tightening force, the inner arc of the crescent main plate 3 is pressed to the tooth top circle of the gear shaft 8, and the outer arc of the crescent secondary plate 5 is pressed to the tooth top circle of the inner ring gear 2; The sealing rod installed in the special-shaped slot two 3.2 / special-shaped slot three 3.3 / special-shaped slot four 3.5 / special-shaped slot five 3.6 provides sealing during the operation of the gear pump, prevents high-pressure oil from leaking into the low-pressure area, causing a large amount of internal leakage; And the two sealing rods on each side also provide two fulcrums for the crescent secondary plate, so that the crescent secondary plate 5 can rotate and move in a small range around the fulcrum during the operation of the gear pump.

[0063] The inner ring gear 2 is arranged with the same number of oil holes 2.1 as the number of teeth, which are in line with the center of the inner ring gear 2, for supplying oil to the back pressure groove and oil inlet and outlet on the pump body.

[0064] The side plate 12 and the front cover 9, the rear cover 13 are provided with special-shaped O-rings 10 and special-shaped retainer rings 11, and the shapes of the special-shaped O-rings 10 and the special-shaped retainer rings 11 match the front cover special-shaped groove one 9.1, the front cover special-shaped groove two 9.3, the rear cover special-shaped groove one 13.2 and the rear cover special-shaped groove two 13.4.

[0065] The test data are as follows in Tables 1-2:

[0066] Table 1

[0067]

[0068] Table 2

[0069]

[0070] Example 2

[0071] The other is the same as example 1, except that the phase angle of the two back pressure grooves is less than the angle formed by the two adjacent through holes on the inner ring gear, that is, less than 25°, and in this example, it is 20°.

[0072] The experimental results are referred to Figures 23-28 , and Tables 3-4 below, the volumetric efficiency is 90.23% at 1500 rpm and 25 MPa pressure difference, which does not meet the factory standard, and the main reason is that the smaller phase angle leads to insufficient sealing arc, and part of the high-pressure oil is taken away from the high-pressure area by the inner ring gear during the operation of the gear pump, causing internal leakage.

[0073] Table 3

[0074]

[0075] Table 4

[0076]

[0077] Example 3

[0078] Other are the same as example 1, except that the two back pressure groove phase angle is greater than the angle of three through holes, the specific embodiment is 38 °. High pressure oil long time trapped in the inner tooth circle passage hole 2.1, cause the damage to the inner tooth circle and pump body sealing area, the experimental results are extremely undesirable (results refer to Figures 29-34 , table 5-6).

[0079] Table 5

[0080]

[0081] Table 6

[0082]

[0083]

[0084] The above are only preferred embodiments of the present application, and are not used to limit the present application, although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacements to some of the technical features. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A bi-directional hydraulic gear pump characterized by: The pump body, the front cover and the rear cover surround to form a cylindrical sealed space, the cylindrical sealed space is internally provided with a gear shaft, an inner gear ring, a crescent main plate, a crescent auxiliary plate, a side plate and a positioning rod, the crescent main plate is provided with six left-right symmetrical special-shaped grooves, the special-shaped grooves include two leaf spring special grooves and four composite function grooves, and the two leaf spring special grooves are arranged at the outermost sides, the leaf spring special grooves are internally provided with leaf springs, and the composite function grooves are internally provided with leaf springs and sealing rods.

2. A bi-directional hydraulic gear pump as claimed in claim 1, characterized in that: The crescent auxiliary plate is provided with an oil passage, and the oil passage is in communication with at least one set of composite function grooves.

3. A bi-directional hydraulic gear pump as in claim 1, wherein: The crescent auxiliary plate is provided with a trapezoidal groove, and the positioning rod includes a trapezoidal part and a trapezoidal rod cylindrical part, and the trapezoidal groove and the trapezoidal part of the positioning rod are matched.

4. A bi-directional hydraulic gear pump as claimed in claim 3, characterized in that: The trapezoidal groove and the trapezoidal part of the positioning rod have a gap one and a gap two.

5. A bi-directional hydraulic gear pump as in claim 1, wherein: The front cover includes a pump body sealing surface, and the pump body sealing surface is symmetrically provided with an oil port A and an oil port B, and is symmetrically provided with a back pressure groove A and a back pressure groove B.

6. A bi-directional hydraulic gear pump as claimed in claim 5, characterized in that: The phase angle of the back pressure groove A and the back pressure groove B is 25-36°.

7. A bi-directional hydraulic gear pump as in claim 1, wherein: The side plate includes a side plate gear shaft hole, a side plate oil guide groove one, a side plate oil guide groove two, a side plate through hole one, a side plate through hole two, a side plate through hole three, a side plate through hole four, a side plate through hole five and a side plate through hole six, and the side plate through hole one and the side plate through hole six are symmetrically arranged, the side plate through hole three and the side plate through hole four are symmetrically arranged, and the side plate through hole two and the side plate through hole five are symmetrically arranged; the front cover includes a front cover special-shaped groove one and a front cover special-shaped groove two, the rear cover includes a rear cover special-shaped groove one and a rear cover special-shaped groove two, and the positions of the side plate through hole two and the side plate through hole three are matched with the positions of the front cover special-shaped groove two and the rear cover special-shaped groove two, and the positions of the side plate through hole four and the side plate through hole five are matched with the positions of the front cover special-shaped groove four and the rear cover special-shaped groove five.

8. A bi-directional hydraulic gear pump as claimed in claim 7, characterized in that: The side plate through hole two extends a side plate eyebrow groove two, the side plate through hole five extends a side plate eyebrow groove three, the side plate eyebrow groove two and the side plate eyebrow groove three jointly point to the gap between the gear shaft and the crescent main plate, the side plate through hole one extends a side plate eyebrow groove one, the side plate through hole six extends a side plate eyebrow groove four, and the side plate eyebrow groove one and the side plate eyebrow groove four jointly point to the gap between the inner gear ring and the crescent auxiliary plate.

9. A bi-directional hydraulic gear pump as in claim 1, wherein: The special-shaped O-shaped ring and the special-shaped retainer ring are matched with the front cover special-shaped groove one, the front cover special-shaped groove two, the rear cover special-shaped groove one and the rear cover special-shaped groove two.

10. A bi-directional hydraulic gear pump as claimed in claim 9, characterized in that: ​

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