CN214660819U

CN214660819U - Self-balancing gear pump

Info

Publication number: CN214660819U
Application number: CN202023339383.5U
Authority: CN
Inventors: 王军强
Original assignee: Ji'nan Boer Power Equipment Co ltd
Current assignee: Ji'nan Boer Power Equipment Co ltd
Priority date: 2020-12-30
Filing date: 2020-12-30
Publication date: 2021-11-09
Anticipated expiration: 2030-12-30

Abstract

The application relates to a self-balancing gear pump, which comprises a shell and a pumping assembly, wherein the shell is internally provided with a main cavity, and the pumping assembly is arranged in the main cavity and used for conveying fluid; the pumping assembly divides the main cavity into a pressure oil cavity and an oil suction cavity, communicating holes communicated with the main cavity are formed in two opposite sides of the shell, the communicating holes communicated with the pressure oil cavity are oil outlets, and the communicating holes communicated with the oil suction cavity are oil suction holes; the pumping assembly comprises a driving gear and a driven gear, the driving gear and the driven gear rotate relative to the shell, the driving gear is meshed with the driven gear and arranged in parallel, and the shell is further provided with a power input hole which is coaxially arranged with the driving gear; the driving gear and the driven gear are helical gears. This application has the effect of the trapped oil phenomenon of alleviating the gear pump.

Description

Self-balancing gear pump

Technical Field

The application relates to the field of mechanical pumps, in particular to a self-balancing gear pump.

Background

Gear pumps are pumps that deliver liquid by virtue of the change in swept volume created by meshing gears. When the two gears are disengaged, the space between the two gears is small and large, vacuum is formed, and liquid is sucked into the tooth grooves. As the gear rotates, liquid is delivered to the discharge chamber. The change in working volume changes from large to small when the gears mesh, forcing liquid into the conduit. The suction chamber and the discharge chamber are separated by a meshing line of two gears.

In the working process of the gear pump, in a time interval when the two pairs of teeth are meshed simultaneously, a part of oil is trapped in a closed oil cavity formed by the two pairs of gears, and the oil cavity is not communicated with an oil suction cavity and is not communicated with an oil pressing cavity. When the volume is reduced from large to small (from the process that the teeth are not meshed to the process that the teeth are meshed), oil in the closed oil cavity is extruded and overflows through the gap, so that the pressure in the closed oil cavity is increased, and the gear is impacted by periodical radial pressure; when the volume is changed from small to large (from tooth meshing to separation), local vacuum and air pocket are formed due to the fact that oil cannot be supplemented, cavitation phenomenon occurs, and vibration and noise are caused. The phenomenon is called oil trapping.

In view of the above-mentioned related art, the inventors consider that the gear pump has a defect of oil trapping phenomenon.

SUMMERY OF THE UTILITY MODEL

In order to alleviate the oily phenomenon of trapping of gear pump, the application provides a self-balancing gear pump.

The application provides a self-balancing gear pump adopts following technical scheme:

a self-balancing gear pump comprises a shell with a main cavity formed inside and a pumping assembly arranged in the main cavity and used for conveying fluid; the pumping assembly divides the main cavity into a pressure oil cavity and an oil suction cavity, communicating holes communicated with the main cavity are formed in two opposite sides of the shell, the communicating holes communicated with the pressure oil cavity are oil outlets, and the communicating holes communicated with the oil suction cavity are oil suction holes; the pumping assembly comprises a driving gear and a driven gear, the driving gear and the driven gear rotate relative to the shell, the driving gear is meshed with the driven gear and arranged in parallel, and the shell is further provided with a power input hole which is coaxially arranged with the driving gear; the driving gear and the driven gear are helical gears.

Through adopting above-mentioned technical scheme, two helical gear meshing in-process, two teeth mesh gradually from one end, and when two tooth one end meshing teeth, the other end of tooth has not meshed yet, and in the period of two pairs of teeth meshing simultaneously, be difficult to form confined space, consequently the difficult oily phenomenon of trapping of appearing.

Optionally, the teeth of the driving gear and the driven gear satisfy the following condition:

wherein:

the length of the teeth along the axial direction of the gear;

is the helix angle of the gear;

is the tooth spacing.

By adopting the technical scheme, the helical angle of the gear is large enough, and when one end of the gear is meshed, the other end of the gear is not meshed, so that the oil trapping phenomenon is further reduced.

Optionally, a balancing assembly for applying axial pressure to the driving gear and the driven gear is arranged on one side of the housing, which is away from the power input hole, and the teeth of the driving gear are far away from the power input hole along the rotation direction.

By adopting the technical scheme, the balance assembly is utilized to apply axial balance force to the driving gear and the driven gear, the axial force of fluid to the driving gear and the driven gear in the working process is balanced by the axial balance force, the axial pressure of the driving gear and the driven gear to the shell is reduced, and the abrasion between the pumping assembly and the shell is reduced.

Optionally, the shell deviates from power input hole one side and has seted up balanced chamber, the shell sets up two holes of sliding with balanced chamber intercommunication, the hole of sliding deviates from the one end and the main cavity room intercommunication in balanced chamber, one the hole of sliding sets up with the driving gear is coaxial, another the hole of sliding sets up with driven gear is coaxial, two all be provided with in the hole of sliding and be the piston of sliding connection with the shell, the slip direction of piston is on a parallel with the axis direction of driving gear, the piston is closed the hole of sliding, balanced runner has been seted up to the shell, balanced runner will balance chamber and pressure oil pocket intercommunication.

By adopting the technical scheme, when the self-balancing gear pump works, fluid in the pressure oil cavity flows into the balancing cavity, and the pressure in the balancing cavity is increased, so that the piston is pushed to slide. The piston applies transverse thrust to the driving shaft and the driven shaft, so that the reaction force of fluid to the driving gear and the driven gear in the working process is balanced.

Optionally, the casing is provided with a pressure-resistant flow passage, one end of the pressure-resistant flow passage is communicated with the pressure oil cavity, and the other end of the pressure-resistant flow passage is communicated with the oil suction cavity.

By adopting the technical scheme, the pressure-resistant flow passage communicates the pressure oil cavity with the oil suction cavity, and when the oil pressure of the oil suction cavity is too high, hydraulic oil can enter the pressure oil cavity through the pressure-resistant flow passage to finish oil drainage of the oil suction cavity.

Optionally, a check valve is installed in the pressure-resistant flow passage, and a flow direction of the check valve is from the oil suction chamber to the pressure oil chamber.

By adopting the technical scheme, the one-way valve is utilized to block the fluid which flows back from the pressure oil cavity to the oil suction cavity, and the reduction of the output oil pressure of the gear pump caused by the existence of the pressure-resistant flow passage is reduced.

Optionally, the shell is provided with a pressure relief runner, one end of the pressure relief runner is communicated with the balance cavity, and the other end of the pressure relief runner is communicated with a space outside the shell.

By adopting the technical scheme, the fluid entering the balance cavity finally flows out of the pump body from the pressure relief flow channel, so that the fluid in the balance cavity flows, the temperature of the fluid in the balance cavity can be diluted, and the gear pump is cooled.

Optionally, the shell is including the pump body of seting up the main cavity room, pump body one end fixedly connected with front end housing, the front end housing is seted up in the power input hole, the balanced end cover of front end housing one end fixedly connected with is kept away from to the pump body, the hole of sliding is seted up in the balanced end cover, the balanced end cover deviates from the one end fixedly connected with rear end cap of the pump body, the lateral wall of rear end cap and the laminating of balanced end cover has been seted up balanced chamber.

By adopting the technical scheme, the main cavity and the balance cavity are convenient to arrange, the whole body is simpler to process, and the processing cost is reduced.

Optionally, the balance end cover is provided with two first distribution oil paths, the two first distribution oil paths are both communicated with the balance flow channel, the first distribution oil paths correspond to the sliding holes in a one-to-one manner, and the first distribution oil paths are circular arcs and use central axes of the corresponding sliding holes as circle centers.

Through adopting above-mentioned technical scheme, utilize first distribution oil circuit to flow into fluid fast dispersion to balanced intracavity with balanced runner to make near oil pressure in two holes that slide more close, make the oil pressure in two holes that slide also more close, reduce the pressure differential that balanced subassembly was applyed driving gear and driven gear, reduce the compressive stress between driving gear and the driven gear.

Optionally, the balance end cover is provided with two second distribution oil paths communicated with the pressure relief flow passage, the second distribution oil paths correspond to the sliding holes in a one-to-one manner, the second distribution oil paths are circular arcs and use central axes of the corresponding sliding holes as circle centers, and the radius of the second distribution oil paths is smaller than that of the first distribution oil paths.

Through adopting above-mentioned technical scheme, utilize the second to distribute the oil circuit and will balance intracavity fluid and concentrate on the pressure release runner more to make two near oil pressures that slide the hole more close, make two oil pressures that slide the downthehole also more close, reduce the pressure differential that balanced subassembly applyed driving gear and driven gear, reduce the compressive stress between driving gear and the driven gear.

In summary, the present application includes at least one of the following beneficial technical effects:

1. utilize the meshing of helical gear to carry fluid, two helical gear meshing in-process, in the period of two pairs of tooth meshing simultaneously, be difficult to form confined space, consequently the difficult oily phenomenon of trapping of appearing to reduce to produce radial pressure impact, vibration and noise because of pumping assembly is trapped oil.

2. A pressure-resistant flow passage for communicating the pressure oil cavity with the oil suction cavity is formed in the shell, and when the oil pressure of the oil suction cavity is too high, hydraulic oil can enter the pressure oil cavity through the pressure-resistant flow passage to finish oil drainage of the oil suction cavity.

3. The balance assembly is installed on the shell and used for applying axial balance force to the driving gear and the driven gear, the axial force of oil pressure discharged from the pressure oil cavity in the working process of the driving gear and the driven gear to the driving gear and the driven gear is balanced by the axial balance force, the axial pressure of the driving gear and the driven gear to the shell is reduced, and abrasion between the pumping assembly and the shell is reduced.

Drawings

Fig. 1 is a perspective view for showing the entirety of an embodiment of the present application.

Fig. 2 is a cross-sectional view of an embodiment of the present application showing a pumping assembly.

Fig. 3 is a cross-sectional view for showing a pressure-proof flow channel according to an embodiment of the present application.

Fig. 4 is a schematic structural diagram for a balance end cover according to an embodiment of the present application.

Description of reference numerals: 100. a housing; 101. a pump body; 102. a front end cover; 103. balancing the end cover; 104. a rear end cap; 105. an oil outlet; 106. an oil suction hole; 107. a power input aperture; 108. a pressure oil chamber; 109. an oil suction cavity; 110. a first distribution oil passage; 111. a sealing groove; 112. a second distribution oil passage; 113. a pressure-resistant flow channel; 114. a one-way valve; 200. a pumping assembly; 201. a driving gear; 203. a driven gear; 204. a drive shaft; 205. a driven shaft; 206. a bushing; 300. a balancing component; 301. a balancing chamber; 302. a sliding hole; 303. a piston; 304. a balance flow channel; 305. a pressure relief flow passage.

Detailed Description

The present application is described in further detail below with reference to figures 1-4.

The embodiment of the application discloses self-balancing gear pump. Referring to fig. 1, the self-balancing gear pump basically includes a housing 100 and a pumping assembly 200. Wherein a pumping assembly 200 is mounted within the housing 100, the pumping assembly 200 being for conveying a fluid.

Referring to fig. 2, the housing 100 includes a pump body 101, a front end cover 102, a balance end cover 103, and a rear end cover 104. The pump body 101 is cylindric, and its axial one end has seted up the main cavity, and the main cavity runs through pump body 101. Two opposite sides of the pump body 101 are both provided with a communicating hole communicated with the main chamber, one is an oil outlet 105, and the other is an oil suction hole 106. The front end cover 102 is fixedly connected to one end of the pump body 101, which is opened with a main chamber. In the embodiment of the present application, the pump body 101 and the front end cover 102 are fixed by bolts. The front end cover 102 is provided with a power input hole 107, and a power structure for driving the self-balancing gear pump transmits power to the pumping assembly 200 through the power input hole 107. The balance end cap 103 is fixedly connected to an end of the pump body 101 away from the front end cap 102, and the rear end cap 104 is fixedly connected to an end of the balance end cap 103 away from the pump body 101. In the embodiment of the present application, the pump body 101 and the balance end cover 103, and the rear end cover 104 and the balance end cover 103 are fixed by bolts.

Referring to fig. 2 and 3, the pumping assembly 200 is located within the main cavity and divides the main cavity into a pressure oil chamber 108 and an oil suction chamber 109, wherein the oil outlet 105 communicates with the pressure oil chamber 108 and the oil suction hole 106 communicates with the oil suction chamber 109. When the pumping assembly 200 is operated, the fluid in the oil suction chamber 109 is transferred to the pressure oil chamber 108, so that the oil suction chamber 109 forms a negative pressure and the pressure oil chamber 108 forms a positive pressure.

Referring to fig. 2, the pumping assembly 200 includes a driving gear 201 and a driven gear 203.

Referring to fig. 2, a driving shaft 204 is coaxially and fixedly connected to the driving gear 201. Both ends of the driving shaft 204 protrude from both ends of the driving gear 201. One end of the driving shaft 204 penetrates the power input hole 107 and extends to the outside of the casing 100. The driving shaft 204 is coaxially connected with an output shaft of a motor, and the motor drives the driving shaft 204 to rotate so as to enable the gear pump to work. In another embodiment of the present application, the output shaft of the motor may be inserted into the power input hole 107 and extend into the housing 100, so as to be coaxially connected to the driving shaft 204.

Referring to fig. 2, a driven shaft 205 is coaxially and fixedly connected to the driven gear 203, and both ends of the driven shaft 205 protrude from both ends of the driven gear 203. The two ends of the driving shaft 204 and the driven shaft 205 are sleeved with bushings 206, and the bushings 206 are tightly attached to the side wall of the main cavity so as to be fixedly connected with the pump body 101. Both the driving shaft 204 and the driven shaft 205 rotate relative to the housing 100 through bushings 206.

Referring to fig. 2, when the driving gear 201 rotates the driven gear 203, the pumping assembly 200 performs fluid transportation. The drive gear 201 and the driven gear 203 are helical gears, and the teeth of the helical gears satisfy the following conditions in the embodiment of the present application:

wherein:

the length of the teeth along the axial direction of the gear;

is the helix angle of the gear;

is the tooth spacing.

In the meshing process of the two helical gears, two teeth which are meshed are gradually meshed from one end, and when one end of each of the two teeth is meshed, the other end of each of the two teeth is not meshed. In the period when two pairs of teeth are meshed simultaneously, a closed space is not easy to form, so that the oil trapping phenomenon is not easy to occur, and the radial pressure impact, vibration and noise caused by the oil trapping of the pumping assembly 200 are reduced.

Referring to fig. 2, when the helical gear conveys fluid, the helical gear receives a reaction force of the fluid parallel to the axial direction of the helical gear. The direction of the reaction force is related to the helical direction of the helical gear. The direction of the reaction force is the direction in which the helical line of the helical gear extends axially along the direction of rotation of the helical gear. The helical line is a term specially used for helical teeth, and because the gear teeth are inclined relative to the gear axis, the intersection line of the gear teeth and the coaxial cylinder of the gear axis is the helical line.

Referring to fig. 2, in the embodiment of the present application, the teeth of the driving gear 201 are distant from the power input hole 107 in the rotation direction, so that the reaction force of the fluid received by the driving gear 201 is directed away from the power input hole 107. The teeth of the driven gear 203 are opposite to the teeth of the driving gear 201, and the rotation directions of the two are also opposite, so the directions of the reaction forces of the fluid received by the driving gear 201 and the driven gear 203 are the same. Under the reaction force, the driving gear 201 and the driven gear 203 press the bushing 206 on the side close to the rear end cover 104, so that the friction force between the two is increased, and the abrasion between the two is further increased.

Referring to fig. 2, to alleviate the above, the balanced gear pump further includes a balancing assembly 300. The counterbalance assembly 300 is used to apply an axial counterbalance force to the drive gear 201 and the driven gear 203 that is in a direction opposite to the reaction force of the fluid.

Referring to fig. 2, a balance cavity 301 is provided on the side wall of the rear end cover 104 attached to the balance end cover 103, two sliding holes 302 communicated with the balance cavity 301 are provided on the balance end cover 103, and one end of the sliding hole 302 departing from the balance cavity 301 is communicated with the main cavity. One of the sliding holes 302 is arranged coaxially with the driving shaft 204, and the other sliding hole 302 is arranged coaxially with the driven shaft 205. The counterbalance assembly 300 includes two pistons 303. Two pistons 303 are respectively arranged in the two sliding holes 302, and the pistons 303 are connected with the balance end cover 103 in a sliding manner. The sliding direction of the piston 303 is parallel to the axial direction of the driving gear 201, and the piston 303 closes the sliding hole 302.

Referring to fig. 3, the housing 100 is opened with a balance flow passage 304 communicating the balance chamber 301 and the pressure oil chamber 108. The balance flow passage 304 is partially opened in the balance cover 103 and partially opened in the pump body 101. Pressure oil chamber 108 and balance chamber 301 are communicated through balance flow passage 304, and when the self-balancing gear pump operates, fluid in pressure oil chamber 108 flows into balance chamber 301, and the pressure in balance chamber 301 rises, so that piston 303 is pushed to slide towards pumping assembly 200. One piston 303 abuts against the driving shaft 204, and the other piston 303 abuts against the driven shaft 205, and applies a thrust force in the lateral direction to the driving shaft 204 and the driven shaft 205, thereby balancing the reaction force of the fluid to the driving gear 201 and the driven gear 203 during operation.

Referring to fig. 2, in the embodiment of the present application, the rear end cover 104 further defines a pressure relief flow passage 305, one end of the pressure relief flow passage 305 is communicated with the balance cavity 301, and the other end is communicated with a space outside the housing 100. The fluid entering the balance cavity 301 finally flows out of the pump body 101 through the pressure relief flow channel 305, so that the fluid in the balance cavity 301 flows, the temperature of the fluid in the balance cavity 301 can be diluted, and the temperature of the gear pump is reduced. To reduce the pollution of the working environment by the fluid flowing out of the pressure relief flow passage 305, a self-balancing gear pump may be installed in the oil tank.

Referring to fig. 4, the balance end cap 103 is provided with an annular seal groove 111, and a seal ring is mounted in the seal groove 111. When the rear end cover 104 is fixedly connected with the balance end cover 103, the rear end cover 104 and the balance end cover 103 compress the sealing ring, so that a sealing effect is achieved.

Referring to fig. 4, two first distribution oil passages 110 are opened at one end of the balance end cover 103 facing the rear end cover 104, and both the two first distribution oil passages 110 are communicated with the balance flow passage 304. The first distribution oil passages 110 correspond to the sliding holes 302 in a one-to-one manner, and the first distribution oil passages 110 are circular arcs and take the central axes of the corresponding sliding holes 302 as the circle centers. Because the flow passage cross section of the first distribution oil passage 110 is larger relative to the rest space of the balance cavity 301, the balance flow passage 304 is quickly dispersed into the balance cavity 301 by the first distribution oil passage 110, the oil pressures near the two sliding holes 302 are closer, the oil pressures in the two sliding holes 302 are also closer, the pressure difference applied to the driving gear 201 and the driven gear 203 by the balance assembly 300 is reduced, and the pressure stress between the driving gear 201 and the driven gear 203 is reduced.

Referring to fig. 4, the balance end cap 103 is provided with two second distribution oil paths 112 communicated with the pressure relief flow passage 305, the second distribution oil paths 112 correspond to the sliding holes 302 in a one-to-one manner, the second distribution oil paths 112 are circular arcs and have a center axis of the corresponding sliding hole 302, and the radius of the second distribution oil paths 112 is smaller than that of the first distribution oil paths 110.

Referring to fig. 4, the second distribution oil passage 112 concentrates the fluid in the balance chamber 301 more on the relief flow passage 305, and brings the oil pressures near the two sliding holes 302 closer to each other, and brings the oil pressures in the two sliding holes 302 closer to each other, thereby reducing the pressure difference applied to the drive gear 201 and the driven gear 203 by the balance assembly 300, and reducing the pressure stress between the drive gear 201 and the driven gear 203.

Referring to fig. 3, the pump body 101 is provided with a pressure-resistant flow passage 113, one end of the pressure-resistant flow passage 113 is communicated with the pressure oil chamber 108, the other end is communicated with the oil suction chamber 109, a check valve 114 is installed in the pressure-resistant flow passage 113, and the flow direction of the check valve 114 is that the oil suction chamber 109 flows to the pressure oil chamber 108. When the oil pressure in the oil suction chamber 109 is too high, the hydraulic oil enters the pressure oil chamber 108 through the pressure-resistant flow passage 113, and the oil drainage of the oil suction chamber 109 is completed. Meanwhile, the check valve 114 blocks the fluid flowing back from the pressure oil chamber 108 to the oil suction chamber 109, thereby reducing the decrease of the output oil pressure of the gear pump due to the pressure-proof flow passage 113.

The implementation principle of a self-balancing gear pump in the embodiment of the application is as follows: the driving gear 201 rotates to drive the driven gear 203 to rotate. The drive gear 201 and the driven gear 203 are helical gears. Two helical gear meshing in-process, two teeth mesh from one end gradually, and when two tooth one end meshing teeth, the other end of tooth has not meshed yet, and in the period of two pairs of teeth meshing simultaneously, be difficult to form confined space, consequently the difficult oily phenomenon of trapping of appearing.

When the self-balancing gear pump operates, the fluid in the pressure oil chamber 108 flows into the balancing chamber 301 through the balancing flow passage 304, and the pressure in the balancing chamber 301 increases, thereby pushing the piston 303 to slide in the direction of the pumping assembly 200. One piston 303 abuts against the driving shaft 204, and the other piston 303 abuts against the driven shaft 205, and applies a thrust force in the lateral direction to the driving shaft 204 and the driven shaft 205, thereby balancing the reaction force of the fluid to the driving gear 201 and the driven gear 203 during operation.

The above embodiments are preferred embodiments of the present application, and the protection scope of the present application is not limited by the above embodiments, so: all equivalent changes made according to the structure, shape and principle of the present application shall be covered by the protection scope of the present application.

Claims

1. A self-balancing gear pump, its characterized in that: comprises a shell (100) with a main cavity arranged inside and a pumping assembly (200) arranged in the main cavity and used for conveying fluid; the pumping assembly (200) divides the main cavity into a pressure oil cavity (108) and an oil suction cavity (109), two opposite sides of the shell (100) are respectively provided with a communication hole communicated with the main cavity, the communication hole communicated with the pressure oil cavity (108) is an oil outlet (105), and the communication hole communicated with the oil suction cavity (109) is an oil suction hole (106); the pumping assembly (200) comprises a driving gear (201) and a driven gear (203), the driving gear (201) and the driven gear (203) rotate relative to the shell (100), the driving gear (201) is meshed with the driven gear (203), the driving gear and the driven gear are arranged in parallel, and the shell (100) is further provided with a power input hole (107) which is coaxially arranged with the driving gear (201); the driving gear (201) and the driven gear (203) are helical gears.

2. A self-balancing gear pump according to claim 1, characterized in that: the teeth of the driving gear (201) and the driven gear (203) satisfy the following condition:

L tanβ≥P

wherein:

l is the length of the teeth along the axial direction of the gear;

beta is the helix angle of the gear;

p is the tooth spacing.

3. A self-balancing gear pump according to claim 1, characterized in that: one side of the shell (100) departing from the power input hole (107) is provided with a balance assembly (300) for applying axial pressure to the driving gear (201) and the driven gear (203), and the teeth of the driving gear (201) are far away from the power input hole (107) along the rotating direction.

4. A self-balancing gear pump according to claim 3, wherein: balance chamber (301) have been seted up to shell (100) one side that deviates from power input hole (107), shell (100) are seted up two and balance chamber (301) intercommunication slide hole (302), slide hole (302) one end and the main cavity room intercommunication that deviates from balance chamber (301), one slide hole (302) and driving gear (201) coaxial arrangement, another slide hole (302) and driven gear (203) coaxial arrangement, two all be provided with in slide hole (302) and be piston (303) of sliding connection with shell (100), the sliding direction of piston (303) is on a parallel with the axis direction of driving gear (201), piston (303) will slide hole (302) and seal, balance runner (304) have been seted up to shell (100), balance chamber (301) and pressure oil pocket (108) intercommunication are balanced runner (304).

5. A self-balancing gear pump according to claim 1, characterized in that: the shell (100) is provided with a pressure-resistant flow passage (113), one end of the pressure-resistant flow passage (113) is communicated with the pressure oil cavity (108), and the other end of the pressure-resistant flow passage (113) is communicated with the oil suction cavity (109).

6. A self-balancing gear pump according to claim 5, wherein: a one-way valve (114) is installed in the pressure-resistant flow passage (113), and the flow direction of the one-way valve (114) is that the oil suction cavity (109) flows to the pressure oil cavity (108).

7. The self-balancing gear pump of claim 4, wherein: the shell (100) is provided with a pressure relief flow channel (305), one end of the pressure relief flow channel (305) is communicated with the balance cavity (301), and the other end of the pressure relief flow channel is communicated with the space outside the shell (100).

8. A self-balancing gear pump according to claim 7, wherein: the shell (100) is including the pump body (101) of seting up the main cavity, the balanced end cover of front end cover (102) one end fixedly connected with is seted up to the pump body (101), front end cover (102) one end fixedly connected with (103) are kept away from to the pump body (101), balanced end cover (103) are seted up in slip hole (302), balanced end cover (103) deviate from one end fixedly connected with rear end cap (104) of the pump body (101), balanced chamber (301) have been seted up to the lateral wall of rear end cap (104) and the laminating of balanced end cover (103).

9. A self-balancing gear pump according to claim 8, wherein: the balance end cover (103) is provided with two first distribution oil ways (110), the two first distribution oil ways (110) are communicated with the balance flow passage (304), the first distribution oil ways (110) correspond to the sliding holes (302) in a one-to-one mode, and the first distribution oil ways (110) are circular arcs and use the central axis of the corresponding sliding holes (302) as the circle center.

10. A self-balancing gear pump according to claim 9, wherein: the balance end cover (103) is provided with two second distribution oil paths (112) communicated with the pressure relief flow passage (305), the second distribution oil paths (112) correspond to the sliding holes (302) in a one-to-one mode, the second distribution oil paths (112) are circular arcs and take the central axes of the corresponding sliding holes (302) as the circle centers, and the radius of the second distribution oil paths (112) is smaller than that of the first distribution oil paths (110).