Micro gear pump

Abstract

The present invention discloses a micro gear pump, comprising: a pump body; a lower shell, mounted on the pump body, the lower shell is provided with an oil inlet and an oil outlet extending from the outside to the upper end surface of the lower shell; a sealing cover, sealingly connected to the lower shell, the inner side of the sealing cover and the upper end surface of the lower shell enclose an oil pressure chamber; a middle shell, a first compression elastic member acts downward on the middle shell to press the lower side of the middle shell against the upper end surface of the lower shell; a driving gear, a driven gear, the upper end surface of the lower shell and the lower side of the middle shell enclose an oil suction chamber, the oil suction chamber is surrounded by the oil pressure chamber except the upper end surface of the lower shell; a rotary drive unit and a magnetic transmission. The present gear pump is different from the traditional micro gear pump in terms of structural layout, the upper shell and a part of the sealing elements are eliminated, and the oil suction chamber adopts a floating closed structure, which can not only reduce the processing accuracy requirements for the middle shell, the lower shell and the sealing cover, but also reduce the internal leakage of the oil as a whole, so that the flow rate tends to be stable.

Description

Technical Field

[0001] The invention relates to the technical field of rotary piston variable displacement pumps, in particular to a micro gear pump. Background Art

[0002] The gear pump is a rotary pump that relies on the change and movement of the working volume formed between the pump cylinder and the meshing gears to transport oil or increase its pressure. The two gears and the pump body form the oil suction chamber and the oil pressure chamber. When the gears rotate, the volume of the space on the gear disengagement side changes from small to large, forming a vacuum, sucking the oil from the oil inlet, and the volume of the space on the gear meshing side changes from large to small, and the oil is pressed out from the oil outlet.

[0003] The pump body of a traditional micro gear pump is mainly composed of an upper shell, a middle shell and a lower shell that are fixedly connected. The structure is complex, and the mating surfaces of these shells need to be sealed with multiple sealing elements, which requires high processing accuracy of the shell parts.

[0004] Moreover, the pressure of the oil outlet and the oil pressure chamber of the gear pump depends on the size of the resistance at the outlet of the gear pump. As the gear rotates continuously, the gear pump also discharges oil continuously. While keeping the gear speed unchanged, as the pressure in the oil pressure chamber increases, the oil flow rate will gradually decrease. On the one hand, due to objective reasons, when the pressure in the oil pressure chamber increases, the viscosity of the oil will increase, and the resistance of the oil to the gear pump will also increase, resulting in a decrease in flow rate; on the other hand, since leakage points are prone to occur at the connections between the various parts that enclose the oil pressure chamber and the oil suction chamber, when the pressure in the oil pressure chamber increases, the more leakage there is, the smaller the oil flow rate. Summary of the invention

[0005] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention provides a micro gear pump that can simplify the structure, reduce the machining accuracy requirements for parts, and reduce the internal leakage of oil to make the flow rate stable.

[0006] The micro gear pump according to the embodiment of the present invention comprises: a pump body; a lower shell, mounted on the pump body, the lower shell is provided with an oil inlet and an oil outlet extending from the outside to the upper end surface of the lower shell, the upper end surface of the lower shell is provided with a first positioning hole, a second positioning hole and a third positioning hole extending in the up-down direction; a sealing cover, sealingly connected to the lower shell, the inner side of the sealing cover and the upper end surface of the lower shell are enclosed to form an oil pressure chamber, the oil pressure chamber is communicated with the oil outlet, the inner top center of the sealing cover is provided with a centering groove aligned with the third positioning hole in the upper and lower directions, the inner side of the sealing cover is provided with a A squeezing portion is provided; a middle shell, the lower side of which is inserted into the first positioning hole through a first positioning column, a first compression elastic member is provided between the upper side of the middle shell and the squeezing portion, the first compression elastic member acts downward on the middle shell to press the lower side of the middle shell against the upper end surface of the lower shell, and a first anti-rotation constraint portion is provided on the middle shell; a driven gear extends axially in the up and down directions, the driven gear is inserted into the second positioning hole through a second positioning column, the driven gear can rotate relative to the second positioning column, and the second positioning column is provided with a first anti-rotation constraint portion that cooperates with the first anti-rotation constraint portion The second anti-rotation constraint portion constrained by the constraint, the lower end of the driven gear is pressed against the upper end surface of the lower shell, and the upper end is pressed against the lower side of the middle shell; the driving gear extends axially in the up and down directions and meshes with the driven gear, and the driving gear is inserted into the third positioning hole and the centering groove through a third positioning column, and the driving gear can rotate relative to the third positioning column, and the lower end of the driving gear is pressed against the upper end surface of the lower shell, and the upper end is pressed against the lower side of the middle shell, and the driving gear, the driven gear, the upper end surface of the lower shell and the lower side of the middle shell enclose an oil suction cavity, The oil suction chamber is surrounded by the oil pressure chamber except for the upper end surface of the lower shell, and the oil suction chamber is connected to the oil inlet; a rotation drive unit and a magnetic transmission device, the magnetic transmission device includes an outer magnetic rotor and an inner magnetic rotor, the inner magnetic rotor is rotatably sleeved on the third positioning column and is connected to the driving gear, a gap is left between the inner magnetic rotor and the inner side of the sealing cover and is connected to the oil pressure chamber, the rotation drive unit is installed on the pump body and is connected to the outer magnetic rotor, the outer magnetic rotor is located on the outer side of the sealing cover, and the rotational power is transmitted to the inner magnetic rotor without contact.

[0007] At least the following beneficial effects are achieved: the gear pump is different from the traditional micro gear pump in terms of structural layout, the upper shell and a part of the sealing elements are eliminated, the inner side of the sealing cover and the upper end face of the lower shell are enclosed to form an oil pressure chamber, the second anti-rotation constraint part of the second positioning column can constrain the first anti-rotation constraint part of the middle shell to prevent the middle shell from rotating, the driving gear, the driven gear, the upper end face of the lower shell and the lower side of the middle shell are enclosed to form an oil suction chamber, the oil suction chamber adopts a floating closed structure, the first compression elastic member acts downward on the middle shell to press the lower side of the middle shell against the upper end face of the lower shell, which can not only reduce the machining accuracy requirements for the middle shell, the lower shell and the sealing cover, but also the oil suction chamber except the upper end face of the lower shell is enclosed to form an oil suction chamber. The outer shell is surrounded by the oil pressure chamber. When the pressure in the oil pressure chamber increases, the pressure of the oil pressure chamber on the middle shell will press the middle shell more tightly against the lower shell, the driving gear and the driven gear, thereby reducing the internal leakage of the oil in the oil pressure chamber from the various pressure surfaces of the middle shell to the oil suction chamber. The oil pressure chamber only needs to ensure the sealed connection between the sealing cover and the lower shell, and there is no other leakage point. The internal leakage of the oil can be reduced as a whole, and the flow rate tends to be stable. In addition, the spatial layout of the oil pressure chamber is ingenious. The oil pressure chamber includes the driving gear, the driven gear, the middle shell, the inner magnetic rotor, the second positioning column and the third positioning column, which is convenient for the oil to directly lubricate the components without designing lubrication holes separately, thereby reducing the processing difficulty.

[0008] According to some embodiments of the present invention, the inner magnetic rotor is key-connected to the driving gear.

[0009] According to some embodiments of the present invention, a transmission sleeve is extended and connected to the upper end of the driving gear, and the outer surface of the transmission sleeve is provided with external splines. An isolation sleeve is injection-molded inside the inner magnetic rotor, and the inner surface of the isolation sleeve is provided with internal splines. The isolation sleeve and the transmission sleeve are both rotatably sleeved on the third positioning column, and the isolation sleeve and the transmission sleeve are spline-connected.

[0010] According to some embodiments of the present invention, a second compression elastic member is provided between the lower end of the third positioning column and the bottom of the third positioning hole, and the second compression elastic member acts on the third positioning column to press the upper end of the third positioning column against the centering groove.

[0011] According to some embodiments of the present invention, the second anti-rotation restraint portion is a step structure arranged at the upper end of the second positioning column, the step structure having a step facade and an arched step plane, the first anti-rotation restraint portion is a notch groove opened on the lower side of the middle shell, the notch groove extends in the up and down directions and has an arched cross-section, the step plane is fitted and embedded in the notch groove, and the notch of the notch groove presses against the step facade.

[0012] According to some embodiments of the present invention, the first compression elastic member is a compression spring, an accommodating blind hole is opened on the upper side of the middle shell, and the first compression elastic member is partially accommodated in the accommodating blind hole.

[0013] According to some embodiments of the present invention, the sealing cover is provided with an annular step extending in a circumferential direction, and the extrusion portion is an inner side surface of the annular step.

[0014] According to some embodiments of the present invention, the outer ring of the lower shell is provided with a boss extending in the circumferential direction, the lower end of the sealing cover is pressed against the upper end surface of the boss, a sealing ring is installed between the inner side of the sealing cover and the outer ring of the lower shell, and the pump body is fastened with an annular pressure plate, and the annular pressure plate and the pump body clamp the outer side surface of the annular step and the lower end surface of the boss respectively.

[0015] According to some embodiments of the present invention, the outer ring of the lower shell is provided with a sealing groove extending in the circumferential direction, the sealing groove is located above the boss, and the sealing ring is partially accommodated in the sealing groove.

[0016] According to some embodiments of the present invention, the rotation driving unit is a motor.

[0017] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The present invention will be further described below with reference to the accompanying drawings and embodiments, wherein:

[0019] Figure 1 It is a structural schematic diagram of an embodiment of the present invention;

[0020] Figure 2 for Figure 1 A cross-sectional view of

[0021] Figure 3 for Figure 2 The enlarged view of point A in the middle;

[0022] Figure 4 for Figure 1 Schematic diagram of the decomposition of

[0023] Figure 5 for Figure 4 The enlarged view of point B in the middle;

[0024] Figure 6 It is a partial structural decomposition schematic diagram of an embodiment of the present invention;

[0025] Figure 7 for Figure 6 Enlarged view of point C in the middle;

[0026] Figure 8 Schematic diagram of the structure of the middle shell of an embodiment of the present invention.

[0027] Figure numbers: pump body 1, lower shell 2, oil inlet 21, oil outlet 22, first positioning hole 23, second positioning hole 24, third positioning hole 25, boss 26, sealing groove 27, sealing cover 3, centering groove 31, extrusion part 32, annular step 33, oil pressure chamber 4, middle shell 5, first anti-rotation constraint part 51, accommodating blind hole 52, driven gear 6, driving gear 7, transmission sleeve 71, external spline 72, oil suction chamber 8, magnetic transmission device 9, external magnetic rotor 91, internal magnetic rotor 92, isolation sleeve 93, internal spline 94, rotation drive unit 10, first positioning column 11, second positioning column 12, second anti-rotation constraint part 121, step facade 1211, step plane 1212, third positioning column 13, first compression elastic member 14, second compression elastic member 15, sealing ring 16, annular pressure plate 17. DETAILED DESCRIPTION

[0028] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0029] In the description of the present invention, it is necessary to understand that descriptions involving orientations, such as up, down, inside, outside, etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the drawings, and are 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 cannot be understood as a limitation on the present invention.

[0030] In the description of the present invention, if there is a description of first, second, and third, it is only for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the sequence of the indicated technical features.

[0031] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installing, connecting, pressing, etc. should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in the present invention based on the specific content of the technical solution.

[0032] Reference Figures 1 to 8 The present invention discloses a micro gear pump, including a pump body 1, a lower shell 2, a sealing cover 3, an oil pressure chamber 4, a middle shell 5, a driven gear 6, a driving gear 7, an oil suction chamber 8, a magnetic transmission 9 and a rotation drive unit 10.

[0033] Among them, refer to Figure 1 and Figure 6 The lower shell 2 is installed on the pump body 1. The lower shell 2 is provided with an oil inlet 21 and an oil outlet 22 extending from the outside to the upper end surface of the lower shell. It can be understood that the oil inlet 21 is used for oil liquid suction, and the oil outlet 22 is used for oil liquid discharge. The upper end surface of the lower shell 2 is provided with a first positioning hole 23, a second positioning hole 24 and a third positioning hole 25 extending in the up-and-down direction. The first positioning hole 23, the second positioning hole 24 and the third positioning hole 25 are spaced apart from each other and are all blind holes.

[0034] Reference Figure 2 and Figure 3 The sealing cover 3 is sealingly connected to the lower shell 2 , and the inner side of the sealing cover 3 and the upper end surface of the lower shell 2 enclose an oil pressure chamber 4 , which is connected to the oil outlet 22 and can press the oil out from the oil outlet 22 .

[0035] Reference Figures 4 to 8 The lower side of the middle shell 5 is inserted into the first positioning hole 23 through the first positioning column 11, and an extrusion portion 32 is provided on the inner side of the sealing cover 3. A first compression elastic member 14 is provided between the upper side of the middle shell 5 and the extrusion portion 32. The first compression elastic member 14 acts downward on the middle shell 5 so that the lower part of the middle shell 5 is pressed tightly against the upper end surface of the lower shell 2.

[0036] Reference Figures 4 to 7 The driven gear 6 extends axially in the up-down direction. The driven gear 6 is inserted into the second positioning hole 24 through the second positioning column 12 . The driven gear 6 can rotate relative to the second positioning column 12 .

[0037] A first anti-rotation constraint portion 51 is provided on the middle shell 5, and a second anti-rotation constraint portion 121 is provided on the second positioning column 12. The first anti-rotation constraint portion 51 cooperates with the second anti-rotation constraint portion 121 to constrain and prevent the middle shell 5 and the second positioning column 12 from rotating relative to the lower shell 2, thereby constraining and positioning the middle shell 5 along the circumferential direction. The lower end of the driven gear 6 presses against the upper end surface of the lower shell 2, and the upper end presses against the lower side of the middle shell 5.

[0038] Reference Figure 2 , Figure 4 , Figure 5 and Figure 6 The driving gear 7 extends axially in the up-down direction and meshes with the driven gear 6. A centering groove 31 is provided at the inner top center of the sealing cover 3, which is aligned with the third positioning hole 25 in the upper and lower directions. The driving gear 7 is inserted into the third positioning hole 25 and the centering groove 31 through the third positioning column 13. The driving gear 7 can rotate relative to the third positioning column 13. The lower end of the driving gear 7 is pressed against the upper end surface of the lower shell 2, and the upper end is pressed against the lower side of the middle shell 5.

[0039] Reference Figure 4 and Figure 5The driving gear 7, the driven gear 6, the upper end surface of the lower shell 2 and the lower side of the middle shell 5 enclose an oil suction chamber 8. The oil suction chamber 8 is surrounded by the oil pressure chamber 4 except for the upper end surface of the lower shell 2. The oil suction chamber 8 is connected to the oil inlet 21 and can suck oil from the oil inlet 21.

[0040] Reference Figure 5 and Figure 6 The oil suction chamber 8 adopts a floating closed structure, and the first compression elastic member 14 acts downward on the middle shell 5 to press the lower part of the middle shell 5 against the upper end surface of the lower shell 2, which can not only reduce the processing accuracy requirements for the middle shell 5, the lower shell 2, and the sealing cover 3, but also the oil suction chamber 8 is surrounded by the pressure oil chamber 4 except for the upper end surface of the lower shell 2. When the pressure of the pressure oil chamber 4 increases, the pressure of the pressure oil chamber 4 on the middle shell 5 will press the middle shell 5 against the lower shell 2, the driving gear 7 and the driven gear 6, reducing the internal leakage of the oil in the pressure oil chamber 4 from the various pressing surfaces of the middle shell 5 to the oil suction chamber 8, and the pressure oil chamber 4 only needs to ensure the sealing connection between the sealing cover 3 and the lower shell 2, and there is no other leakage point, which can reduce the internal leakage of the oil as a whole and make the flow rate tend to be stable;

[0041] Reference Figure 2 and Figure 6 The magnetic transmission device 9 includes an outer magnetic rotor 91 and an inner magnetic rotor 92. The inner magnetic rotor 92 is rotatably sleeved on the third positioning column 13 and is transmission-connected to the driving gear 7. A gap is left between the inner magnetic rotor 92 and the inner side of the sealing cover 3 and is connected to the oil pressure chamber 4.

[0042] Reference Figure 1 and Figure 2 The rotation drive unit 10 is installed on the pump body 1 and is connected to the external magnetic rotor 91. The external magnetic rotor 91 is located on the outside of the sealing cover 3 and transmits the rotational power to the internal magnetic rotor 92 without contact. While the internal magnetic rotor 92 can receive the rotational power, it can also be sealed in the oil pressure chamber 4 to prevent leakage.

[0043] The rotary drive unit 10 can be a motor. When the rotary drive unit 10 drives the driving gear 7 to rotate through the magnetic transmission device 9, the driven gear 6 rotates accordingly. The volume of the oil suction chamber 8 formed by the space on the gear disengagement side of the driven gear 6 and the driving gear 7 changes from small to large, forming a vacuum, sucking oil from the oil inlet 21, and the volume of the oil pressure chamber 4 formed by the space on the gear meshing side of the driven gear 6 and the driving gear 7 changes from large to small, and the oil is pressed out from the oil outlet 22.

[0044] The gear pump is different from the traditional micro gear pump in terms of structural layout. The upper shell and a part of the sealing elements are eliminated. The inner side of the sealing cover 3 and the upper end surface of the lower shell 2 enclose an oil pressure chamber 4. The second anti-rotation constraint portion 121 of the second positioning column 12 can constrain the first anti-rotation constraint portion 51 of the middle shell 5 to prevent the middle shell 5 from rotating.

[0045] Reference Figure 2 The spatial layout of the oil pressure chamber 4 is ingenious. The oil pressure chamber 4 includes the driving gear 7, the driven gear 6, the middle shell 5, the inner magnetic rotor 92, the second positioning column 12 and the third positioning column 13, which is convenient for the oil to directly lubricate the components without designing additional lubrication holes, thereby reducing the processing difficulty.

[0046] Reference Figure 2 , Figure 4 and Figure 6 , the inner magnetic rotor 92 and the driving gear 7 can be connected by a key. In some embodiments, the upper end of the driving gear 7 is extended and connected with a transmission sleeve 71, and the outer surface of the transmission sleeve 71 is provided with an outer spline 72. The inner surface of the inner magnetic rotor 92 is injection-molded with a spacer sleeve 93, and the inner surface of the spacer sleeve 93 is provided with an inner spline 94. The spacer sleeve 93 and the transmission sleeve 71 are both rotatably sleeved on the third positioning column 13, and the spacer sleeve 93 and the transmission sleeve 71 are spline-connected, so that the inner magnetic rotor 92 can transmit the rotational power to the driving gear 7.

[0047] It should be emphasized that the outer splines 72 and the inner splines 94 are both located in the oil pressure chamber 4 , and the oil in the oil pressure chamber 4 can directly lubricate the outer splines 72 and the inner splines 94 .

[0048] In addition, a second compression elastic member 15 may be disposed between the lower end of the third positioning column 13 and the bottom of the third positioning hole 25. Figure 2 and Figure 6 The second compression elastic member 15 acts on the third positioning column 13 to press the upper end of the third positioning column 13 against the centering groove 31. The combined design of the spline connection structure and the second compression elastic member 15 can allow the external spline 72 and the internal spline 94 to float relative to each other in the up and down directions, so that the inner magnetic rotor 92 and the outer magnetic rotor 91 can be automatically aligned when they are non-contact matched. It is also convenient for the third positioning column 13 to be assembled between the third positioning hole 25 and the centering groove 31, and can always be centered with the centering groove 31, thereby ensuring the stability of the rotation of the inner magnetic rotor 92 and the driving gear 7, reducing noise, and reducing the processing accuracy of each component, compensating for the processing error of the sealing cover 3.

[0049] The second compression elastic member 15 may specifically be a compression spring.

[0050] In some embodiments, reference Figures 6 to 8The second anti-rotation constraint part 121 is a step structure arranged at the upper end of the second positioning column 12. The second anti-rotation constraint part 121 has a step facade 1211 and an arched step plane 1212. The first anti-rotation constraint part 51 is a notch groove opened on the lower side of the middle shell 5. The first anti-rotation constraint part 51 extends in the up and down directions and has an arched cross-section. The step plane 1212 is fitted and embedded in the first anti-rotation constraint part 51. The notch of the first anti-rotation constraint part 51 is pressed against the step facade 1211. The second anti-rotation constraint part 121 can clamp the first anti-rotation constraint part 51 to prevent the middle shell 5 from rotating relative to the first positioning column 11, thereby ensuring that the middle shell 5 is in a relatively correct position. At the same time, the first anti-rotation constraint part 51 also relatively clamps the second anti-rotation constraint part 121 to prevent the second positioning column 12 from rotating around its own axial direction. The two constrain each other to facilitate the alignment and assembly of the middle shell 5.

[0051] Reference Figure 4 and Figure 6 The first compression elastic member 14 may be a compression spring, and a blind hole 52 is provided on the upper side of the middle shell 5, and a portion of the first compression elastic member 14 is accommodated in the blind hole 52. In some embodiments, referring to Figure 3 and Figure 6 The sealing cover 3 is provided with an annular step 33 extending in the circumferential direction. The extrusion portion 32 is the inner side surface of the annular step 33. The inner side surface of the annular step 33 presses against the upper end of the first compression elastic member 14, so that the first compression elastic member 14 is compressed by the inner side surface of the annular step 33 and the accommodating blind hole 52, so that the middle shell 5 is always pressed against the upper end surface of the lower shell 2, which facilitates the assembly of the middle shell 5 and the first compression elastic member 14.

[0052] The first compression elastic member 14 may specifically be a compression spring.

[0053] In some embodiments, reference Figures 2 to 4 The outer ring of the lower shell 2 is provided with a circumferentially extending boss 26, the lower end of the sealing cover 3 is pressed against the upper end surface of the boss 26, a sealing ring 16 is installed between the inner side of the sealing cover 3 and the outer ring of the lower shell 2, and the pump body 1 is fastened with an annular pressure plate 17, the annular pressure plate 17 and the pump body 1 respectively clamp the outer side surface of the annular step 33 and the lower end surface of the boss 26 up and down to ensure the sealing connection between the sealing cover 3 and the lower shell 2 to prevent leakage of the oil pressure chamber 4.

[0054] In some embodiments, reference Figure 3 The outer ring of the lower shell 2 is provided with a sealing groove 27 extending along the circumferential direction. The sealing groove 27 is located above the boss 26. The sealing ring 16 is partially accommodated in the sealing groove 27 to prevent the sealing ring 16 from shifting, thereby further improving the sealing performance.

[0055] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0056] Of course, the present invention is not limited to the above-mentioned embodiments, and those skilled in the art may make equivalent modifications or substitutions without violating the spirit of the present invention, and these equivalent modifications or substitutions are all included in the scope defined by the claims of this application.

Claims

1. A micro gear pump, characterized in that: include: Pump body; A lower shell is mounted on the pump body, the lower shell is provided with an oil inlet and an oil outlet extending from the outside to the upper end surface of the lower shell, and the upper end surface of the lower shell is provided with a first positioning hole, a second positioning hole and a third positioning hole extending in the up-down direction; A sealing cover is sealingly connected to the lower shell, the inner side of the sealing cover and the upper end surface of the lower shell enclose an oil pressure chamber, the oil pressure chamber is communicated with the oil outlet, a centering groove aligned with the third positioning hole is provided at the center of the inner top of the sealing cover, and an extrusion portion is provided on the inner side of the sealing cover; The middle shell is inserted into the first positioning hole at the lower side through the first positioning column, a first compression elastic member is arranged between the upper side of the middle shell and the extrusion portion, the first compression elastic member acts downward on the middle shell to press the lower side of the middle shell against the upper end surface of the lower shell, and a first anti-rotation constraint portion is arranged on the middle shell, the first anti-rotation constraint portion is a notch groove opened on the lower side of the middle shell, and the first anti-rotation constraint portion extends in the up-down direction and has an arcuate cross section; The driven gear extends axially in the up-down direction, the driven gear is inserted into the second positioning hole through the second positioning column, the driven gear can rotate relative to the second positioning column, the second positioning column is provided with a second anti-rotation constraint portion that cooperates and constrains with the first anti-rotation constraint portion, the second anti-rotation constraint portion is a step structure arranged at the upper end of the second positioning column, the second anti-rotation constraint portion has a step vertical surface and an arched step plane, the step plane is fitted and embedded in the first anti-rotation constraint portion, the notch of the first anti-rotation constraint portion is pressed against the step vertical surface, the lower end of the driven gear is pressed against the upper end surface of the lower shell, and the upper end is pressed against the lower side of the middle shell; A driving gear extends axially in the up-down direction and meshes with the driven gear. The driving gear is inserted into the third positioning hole and the centering groove through a third positioning column. The driving gear can rotate relative to the third positioning column. The lower end of the driving gear presses against the upper end surface of the lower shell, and the upper end presses against the lower side of the middle shell. The driving gear, the driven gear, the upper end surface of the lower shell and the lower side of the middle shell form an oil suction chamber. The oil suction chamber is surrounded by the oil pressure chamber except for the upper end surface of the lower shell, and the oil suction chamber is communicated with the oil inlet. A rotational drive unit and a magnetic transmission, wherein the magnetic transmission comprises an outer magnetic rotor and an inner magnetic rotor, wherein the inner magnetic rotor is rotatably sleeved on the third positioning column and is transmission-connected to the driving gear, wherein a gap is left between the inner magnetic rotor and the inner side of the sealing cover and the inner magnetic rotor is connected to the oil pressure chamber, wherein the rotational drive unit is mounted on the pump body and transmission-connected to the outer magnetic rotor, wherein the outer magnetic rotor is located on the outer side of the sealing cover and transmits rotational power to the inner magnetic rotor without contact.

2. The micro gear pump according to claim 1, characterized in that: The inner magnetic rotor is key-connected to the driving gear.

3. The micro gear pump according to claim 2, characterized in that: The upper end of the driving gear is extended and connected with a transmission sleeve, the outer surface of the transmission sleeve is provided with external splines, the interior of the inner magnetic rotor is injection-molded with an isolation sleeve, the inner surface of the isolation sleeve is provided with internal splines, the isolation sleeve and the transmission sleeve are both rotatably sleeved on the third positioning column, and the isolation sleeve and the transmission sleeve are spline-connected.

4. The micro gear pump according to claim 3, characterized in that: A second compression elastic member is provided between the lower end of the third positioning column and the bottom of the third positioning hole, and the second compression elastic member acts on the third positioning column to press the upper end of the third positioning column tightly against the centering groove.

5. The micro gear pump according to claim 1, characterized in that: The first compression elastic member is a compression spring, and an accommodating blind hole is opened on the upper side of the middle shell, and the first compression elastic member is partially accommodated in the accommodating blind hole.

6. The micro gear pump according to claim 1 or 5, characterized in that: The sealing cover is provided with an annular step extending in the circumferential direction, and the extrusion portion is the inner side surface of the annular step.

7. The micro gear pump according to claim 6, characterized in that: The outer ring of the lower shell is provided with a boss extending in the circumferential direction, the lower end of the sealing cover is pressed against the upper end surface of the boss, a sealing ring is installed between the inner side of the sealing cover and the outer ring of the lower shell, and the pump body is fastened with an annular pressure plate, and the annular pressure plate and the pump body clamp the outer side surface of the annular step and the lower end surface of the boss respectively.

8. The micro gear pump according to claim 7, characterized in that: The outer ring of the lower shell is provided with a sealing groove extending in the circumferential direction, the sealing groove is located above the boss, and the sealing ring is partially accommodated in the sealing groove.

9. The micro gear pump according to claim 1, characterized in that: The rotation driving unit is a motor.

Images