A precision internal gear pump

Abstract

The present invention provides a precision internal gear pump, which includes a pump housing. A through hole is provided in the middle of the pump housing, and a transmission shaft passes through the through hole. An external gear is provided in the pump housing, and an internal gear is internally meshed with the external gear. An axial hole adapted to the transmission shaft is provided in the middle of the internal gear. An eccentric distance space is formed between the external gear and the internal gear, and a crescent plate is provided in this space. The teeth of the internal gear are in a straight line form, and the teeth of the external gear are in an involute form. A flow guiding gap is provided at the meshing position between the internal gear and the external gear. For the precision internal gear pump provided by the present invention, through the improvement of the teeth of the external gear and the internal gear, the friction force during the meshing of the external gear and the internal gear can be effectively reduced, which not only prolongs the service life of the pump, but also avoids the problems that the coolant or cutting fluid transported by the pump has too high a temperature and contains debris. The setting of the flow guiding gap avoids the problems that the coolant or cutting fluid at the meshing position has too high a pressure and temperature rise due to the meshing extrusion of the internal gear and the external gear.

Description

Technical Field

[0001] The present invention relates to the field of pumps, and particularly to a precision internal gear pump. Background Art

[0002] In machining, it is generally necessary to apply coolant or cutting fluid to the machined part to facilitate the smooth continuation of machining. This requires a pump with a relatively large pressure to transport the coolant or cutting fluid. Gear pumps can provide a relatively large pressure in the transport system, but there are certain problems when the existing gear pumps are in use.

[0003] Most of the inner and outer tooth teeth of the existing gear pumps are of arc-shaped or straight structures. The tooth teeth with double straight structures have more friction, serious gear damage, and are prone to generating a large amount of heat. The tooth teeth with double arc-shaped structures have dense meshing. When applying coolant or cutting fluid, they are prone to heating due to excessive pressure, and the relatively large pressure is also likely to cause the inner and outer gears to jam. At the same time, for the tooth structure with double arc-shaped structures, there may be multiple positions where the tooth teeth are completely in contact at the tooth meshing part. This results in the inability of the coolant or cutting fluid inside the tooth teeth (i.e., at the meshing part of the outer gear and the inner gear) to flow. As the space is compressed and becomes smaller, the coolant or cutting fluid inside will form a relatively large pressure, causing the temperature of the coolant or cutting fluid to rise, and even leading to the jamming of the meshing of the inner and outer gears inside. Finally, due to the existence of the above two reasons, the pressure boost of the existing traditional pumps can only reach about 2 MPa, which is difficult to adapt to the pressure boost intensity under the existing usage conditions. Therefore, neither of the two forms of gear pumps is suitable for the work of applying coolant or cutting fluid in machining. Summary of the Invention

[0004] (1) Technical Problems to be Solved

[0005] The technical problem to be solved by the present invention is to provide a precision internal gear pump, which can well solve the problems existing in the above gear pumps, such as excessive gear meshing friction, large amount of heat, large pressure on the internal cutting fluid or coolant caused by the closed space, and rising temperature.

[0006] (2) Technical Solutions

[0007] To solve the above technical problems, the present invention provides a precision internal meshing gear pump, which includes a pump housing. A through hole is provided in the middle of the pump housing, and a transmission shaft passes through the through hole. An external gear is provided in the pump housing, and an internal gear meshes with the external gear internally. A shaft hole adapted to the transmission shaft is provided in the middle of the internal gear. An eccentric distance space is formed between the external gear and the internal gear, and a crescent plate is provided in this space. The teeth of the internal gear are in a straight line form, and the teeth of the external gear are in an involute form. A flow guiding gap is spaced at the meshing position between the internal gear and the external gear. During operation, when the transmission shaft drives the external gear to rotate through the internal gear, only one surface of the meshing teeth of the internal gear and the external gear has a fitting contact surface. This fitting contact surface divides the flow guiding gap into two, and each of the two divided flow guiding gaps has no closed section. By improving the tooth shapes of the external gear and the internal gear, the problems of large friction between the external gear and the internal gear, excessive oil pressure at the meshing position between the external gear and the internal gear, resulting in too high temperature, and easy jamming between the external gear and the internal gear can be effectively solved.

[0008] The pump housing includes an upper housing and a lower housing. A gear groove adapted to the external gear is provided inside the lower housing. An oil inlet groove and an oil outlet groove communicating with the gear groove are further provided inside the lower housing. The oil inlet groove communicates with an oil inlet hole on the side wall of the lower housing, and the oil outlet groove communicates with an oil outlet hole on the other side wall of the lower housing. The overall conveying process is that cutting fluid or coolant enters the oil inlet groove from the oil inlet hole, and through the meshing of the internal gear and the external gear, while conveying the liquid, a relatively large pressure can also be formed to convey the liquid out, so as to form a relatively large ejection force when the coolant or cutting fluid is ejected, suitable for the use of machine tool processing.

[0009] As a preferred technical solution of the present invention, a broadening groove and a branch groove communicating with the oil outlet groove are further provided inside the lower housing. Among them, the broadening groove broadens one side of the oil outlet groove close to the meshing position of the internal gear and the external gear, and the branch groove extends the oil outlet groove. When the coolant or cutting fluid is transferred from the oil inlet groove to the oil outlet groove through the meshing and rotation of the internal gear and the external gear, by setting the broadening groove near the meshing position of the internal gear and the external gear, it can accelerate the oil conveyed through the meshing of the external gear and the internal gear to enter the oil outlet groove, effectively avoiding the problems of excessive oil pressure and temperature caused by slow oil outlet at the meshing position. The setting of the branch groove can release the coolant or cutting fluid in the meshing teeth in advance, further reducing the oil pressure in the meshing teeth.

[0010] As a preferred technical solution of the present invention, a rotating housing adapted to the transmission shaft is provided in the middle of the lower housing. A connecting groove is further provided inside the lower housing, and the connecting groove connects the oil outlet groove and the rotating housing. The connecting groove can convey a small part of the coolant or cutting fluid into the rotating housing, reducing the friction between the rotating housing and the lower housing.

[0011] As a preferred technical solution of the present invention, a communication hole is provided between the oil inlet groove and the through hole; when the external gear and the internal gear rotate in opposite directions, the coolant or cutting fluid with a relatively high pressure in the oil inlet groove passes through the communication hole to break and discharge the second sealing ring at the lower end, avoiding a relatively high pressure inside the body.

[0012] As a preferred technical solution of the present invention, the upper shell and the lower shell are connected by bolts, and a first sealing ring is provided at the connection between the upper shell and the lower shell; to ensure the sealing of the connection between the upper shell and the lower shell.

[0013] As a preferred technical solution of the present invention, a sealing cover adapted to the through hole is provided on the side of the lower shell away from the upper shell, and a second sealing ring is provided at the connection between the sealing cover and the through hole; to ensure the sealing performance at the lower end of the lower shell.

[0014] As a preferred technical solution of the present invention, the crescent plate and the lower shell are of an integrally formed structure; to ensure the stability of the crescent plate.

[0015] As a preferred technical solution of the present invention, the outer side wall of the crescent plate is in precise dynamic fit with the teeth of the external gear, and the inner side wall of the crescent plate is in precise dynamic fit with the teeth of the internal gear; through the cooperation of the crescent plate with the external gear and the internal gear, the transportation and pressure increase of the coolant or cutting fluid are realized.

[0016] As a preferred technical solution of the present invention, a positioning groove and a positioning rod are provided on the lower shell, and the upper shell is adapted to the lower shell; the setting of the positioning groove and the positioning rod facilitates the positioning and installation of the upper shell and the lower shell.

[0017] (III) Beneficial effects

[0018] 1. The present invention provides a precision internal meshing gear pump, which can effectively reduce the frictional force when the external gear and the internal gear mesh through the improvement of the teeth of the external gear and the internal gear, not only extending the service life of the pump, but also avoiding the excessive temperature and the presence of debris in the coolant or cutting fluid transported through the pump; at the same time, the setting of the diversion gap can also ensure that the coolant or cutting fluid still has a certain fluidity when passing through the meshing and transportation of the internal gear and the external gear, avoiding the problems of excessive pressure and temperature rise of the coolant or cutting fluid at the meshing part due to the meshing extrusion of the internal gear and the external gear.

[0019] 2. The present invention provides a precision internal meshing gear pump, which can enable the coolant or cutting fluid transported through the meshing of the internal gear and the external gear to relieve pressure in advance through the setting of the branch groove, avoiding its excessive temperature, and the setting of the broadening groove can ensure that the coolant or cutting fluid transported through the meshing of the internal gear and the external gear can be quickly discharged, further avoiding its excessive temperature.

[0020] 3. The present invention provides a precision internal gear pump. The arrangement of its communication holes can prevent coolant or cutting fluid from passing through the communication holes and damaging the second sealing ring when the pressure generated inside the pump during reverse operation is relatively high, thereby realizing the release of internal pressure to protect the pump body.

[0021] 4. The present invention provides a precision internal gear pump, in which the crescent plate and the lower shell are integrally formed. This fully ensures the accurate and firm position of the crescent plate between the external gear and the internal gear, and guarantees the stability of the crescent plate during operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a schematic diagram of the overall structure of the present invention;

[0023] Figure 2 is an exploded view of the overall structure of the present invention;

[0024] Figure 3 is a schematic diagram of the first internal structure of the present invention;

[0025] Figure 4 is a schematic diagram of the second internal structure of the present invention;

[0026] Figure 5 is a schematic diagram of the first internal structure of the lower shell of the present invention;

[0027] Figure 6 is a schematic diagram of the second internal structure of the lower shell of the present invention;

[0028] Figure 7 is a schematic diagram of the external structure of the lower shell of the present invention;

[0029] Figure 8 is a schematic diagram of the connection structure between the transmission shaft, internal gear and external gear of the present invention;

[0030] Figure 9 is a schematic diagram of the meshing state structure of the internal gear and external gear of the present invention.

[0031] Wherein: 1 is the pump housing, 11 is the upper shell, 12 is the lower shell, 121 is the gear groove, 122 is the oil inlet groove, 123 is the oil outlet groove, 124 is the oil inlet hole, 125 is the oil outlet hole, 126 is the widened groove, 127 is the branch groove, 128 is the rotating housing, 129 is the communication groove, 13 is the bolt, 14 is the first sealing ring, 15 is the positioning groove, 16 is the positioning rod, 2 is the through hole, 3 is the transmission shaft, 4 is the external gear, 5 is the internal gear, 6 is the shaft hole, 7 is the crescent plate, 8 is the diversion gap, 9 is the communication hole, 10 is the sealing cover, 101 is the second sealing ring. DETAILED DESCRIPTION OF THE INVENTION

[0032] The following will further describe in detail the specific embodiments of the present invention in conjunction with the accompanying drawings and embodiments. The following embodiments are used to illustrate the present invention, but are not used to limit the scope of the present invention.

[0033] Embodiment 1:

[0034] Referring to Figures 1 to 4 , the technical solution provided by the present invention is: a precision internal gear pump, including a pump housing 1. A through hole 2 is provided in the middle of the pump housing 1, and a drive shaft 3 passes through the through hole 2. An external gear 4 is provided in the pump housing 1. An internal gear 5 is internally meshed with the external gear 4, and a shaft hole 6 adapted to the drive shaft 3 is provided in the middle of the internal gear 5. An eccentric space is formed between the external gear 4 and the internal gear 5, and a crescent plate 7 is provided in this space. The teeth of the internal gear 5 are in a straight line form, and the teeth of the external gear 4 are in an involute form. The involute form can also be an arc. There is a diversion gap 8 at the meshing portion between the internal gear 5 and the external gear 4; during operation, when the drive shaft 3 drives the external gear 4 to rotate through the internal gear 5, the teeth of the internally meshed internal gear 5 and external gear 4 have a contact surface only on one surface. This contact surface divides the diversion gap 8 into two, and each of the two divided diversion gaps 8 has no closed section; the external gear 4 meshes with the internal gear 5, and the drive shaft 3 can drive the external gear 4 to rotate through the internal gear 5. That is, under the action of the drive shaft 3, the internal gear 5 drives the external gear 4 to rotate counterclockwise, realizing the transportation and pressurization of coolant or cutting fluid.

[0035] It should be supplemented and explained that: there is a diversion gap 8 at the meshing portion between the internal gear 5 and the external gear 4. The meshing at this meshing portion is defined in this embodiment as that when the teeth of the internal gear 5 enter the space between two adjacent teeth of the external gear 4, it is meshing, and vice versa; this contact surface divides the diversion gap 8 into two. These two refer to that when the internal gear 5 drives the external gear 4 to rotate, there will be a contact surface to push the external gear 4 to rotate, thus dividing the originally continuous diversion gap 8 into two; and each of the two divided diversion gaps 8 has no closed section. The closed section means that when the internal gear 5 drives the external gear 4 to rotate, there is only one tooth engagement surface between the external gear 5 and the internal gear 4 that divides the diversion gap 8 into two, and there will be no more engagement surfaces to divide the diversion gap 8 into more segments to form a closed space. For further convenient understanding, assume that the diversion gap 8 is divided into three segments by two contact surfaces, and the diversion gap 8 between the two contact surfaces is the closed section. In the present invention, there is only one contact surface that divides the diversion gap 8 into two. In the non-operating state, when there is no pushing contact surface between the external gear 4 and the internal gear 5, the diversion gap 8 is a complete one.

[0036] Furthermore, there is a flow guiding gap 8 at the meshing position between the internal gear 5 and the external gear 4; the following is a further supplementary explanation for this sentence; during the meshing rotation process, the teeth of the external gear 4 will not completely fit the space between adjacent teeth of the internal gear 5, so there will be a flow guiding gap, and vice versa. The teeth of the external gear 4 are in a straight line form, and after removing the upper and lower surfaces, it has three surfaces. The teeth of the internal gear 5 are in an involute form, and after removing the upper and lower surfaces, it has three surfaces. During the meshing process of the external gear 4 and the internal gear 5, for both the teeth of the external gear 4 and the internal gear 5, only one surface will fit each other to transmit power to drive the rotation of the external gear 4, and this surface is one of the three surfaces after removing the upper and lower surfaces of the tooth.

[0037] Further, refer to Figure 8 and Figure 9 Since the teeth of the internal gear 5 are in a straight line form, the teeth of the external gear 4 are in an involute form, and there is a flow guiding gap 8 at the meshing position between the internal gear 5 and the external gear 4, during the meshing rotation process of the internal gear 5 and the external gear 4, there is only one place where the teeth of the internal gear 5 are in close contact and transmission with the teeth of the external gear 4, so that the meshing of the teeth of the internal gear 5 and the external gear 4 does not form a closed space. The setting of the flow guiding gap 8 ensures the flow of coolant or cutting fluid at the meshing position, thus ensuring that during the process of the coolant or cutting fluid being transported through the meshing of the internal gear 5 and the external gear 4, a high-pressure closed space will not be formed, resulting in the temperature rise of the coolant or cutting fluid. This effectively solves the problem that when using coolant or cutting fluid in machining, the temperature of the coolant or cutting fluid will not rise due to pump transportation and will not contain friction debris.

[0038] Furthermore, refer to Figure 9 Since the teeth of the internal gear 5 are in a straight line form and the teeth of the external gear 4 are in an involute form, during the meshing rotation process, the contact area between the external gear 4 and the internal gear 5 is small, reducing the friction between the external gear 4 and the internal gear 5. This not only avoids large friction and a large amount of heat generation between the external gear 4 and the internal gear 5, but also extends the service life of the pump.

[0039] Refer to Figure 5 and Figure 6, the pump housing 1 includes an upper housing 11 and a lower housing 12. Inside the lower housing 12, there is a gear groove 121 adapted to the external gear 4. Inside the lower housing 12, there are also an oil inlet groove 122 and an oil outlet groove 123 connected to the gear groove 121. The oil inlet groove 122 is connected to an oil inlet hole 124 on the side wall of the lower housing 12, and the oil outlet groove 123 is connected to an oil outlet hole 125 on the other side wall of the lower housing 12. The size of the oil inlet hole 124 is larger than that of the oil outlet hole 125. On the inner sides of both the upper housing 11 and the lower housing 12, there are corresponding positioning grooves 15 and positioning rods 16, which facilitate the positioning and installation of the upper housing 11 and the lower housing 12. During operation, the oil inlet hole 124 of the pump is connected to an oil inlet pipe, and the oil outlet hole 125 is connected to an oil outlet pipe. In this embodiment, the oil inlet pipe can be filled with coolant or cutting fluid. The coolant or cutting fluid enters from the oil inlet hole 124 and is discharged from the oil outlet hole 125 under the action of the meshing and conveying of the external gear 4 and the internal gear 5 of the pump. The coolant or cutting fluid ejected from the pump will have a strong ejection force due to the action of the pump internal pressure, thus meeting the need for the coolant or cutting fluid to be sprayed onto the machining part during machining.

[0040] Further, the lower housing 12 is provided with positioning grooves 15 and positioning rods 16, and the upper housing 11 is adapted to the lower housing 12. The lower housing 12 is provided with positioning grooves 15 and positioning rods 16, and the upper housing is also provided with positioning rods 16 adapted to the positioning grooves 15 and positioning grooves 15 adapted to the positioning rods 16, which greatly facilitates the positioning and installation of the upper housing 11 and the lower housing 12.

[0041] Refer to Figure 6 , inside the lower housing 12, there are also a widened groove 126 and a branch groove 127 connected to the oil outlet groove 123. Among them, the widened groove 126 widens one side of the oil outlet groove 123 close to the meshing position of the internal gear 5 and the external gear 4, and the branch groove 127 extends the oil outlet groove 123 towards the meshing position of the external gear 4 and the internal gear 5. During operation, although the coolant or cutting fluid will not form a completely closed space to cause a large pressure during the process of being meshed and conveyed by the external gear 4 and the internal gear 5, due to the continuous rotation and change of the tooth meshing of the external gear 4 and the internal gear 5, the coolant or cutting fluid inside the meshing teeth will still be affected by a certain pressure. The branch groove 127 extends the oil outlet groove 123 towards the meshing position of the external gear 4 and the internal gear 5, which can release the coolant or cutting fluid at the gear meshing position in advance, avoiding its temperature rise due to the pressure formed by the meshing of the external gear 4 and the internal gear 5. Through the settings of the branch groove 127 and the widened groove 126, it is fully ensured that when the external gear 4 and the internal gear 5 mesh and convey the coolant or cutting fluid, high pressure will not be formed to cause the external gear 4 and the internal gear 5 inside the pump body to be jammed.

[0042] Furthermore, a widened groove 126 is provided on one side of the oil outlet groove 123 close to the meshing position of the inner gear 5 and the outer gear 4. To some extent, it can be understood that the flow area of the oil outlet groove 123 on one side close to the meshing position of the inner gear 5 and the outer gear 4 is widened, so as to ensure that the coolant or cutting fluid at the meshing position of the inner gear 5 and the outer gear 4 can be quickly discharged.

[0043] Refer to Figure 5 , a rotating shell 128 adapted to the transmission shaft 3 is provided in the middle of the lower shell 12. A communication groove 129 is also provided inside the lower shell 12, and the communication groove 129 connects the oil outlet groove 123 and the rotating shell 128. During operation, since there is also a rotating shell 128 between the transmission shaft 3 and the through hole 2 on the lower shell 12 when the transmission shaft 3 drives the inner gear 5 to rotate, and the communication groove 129 connects the oil outlet groove 123 and the rotating shell 128, a small part of the liquid in the pump body can enter the rotating shell 128, which can lubricate the part between the transmission shaft 3 and the rotating shell 128 or between the rotating shell 128 and the through hole 2, and reduce the temperature rise caused by friction in this part.

[0044] Furthermore, first, the symmetry center line of the oil inlet groove 122 and the oil outlet groove 123 is defined as line a. The radius of the widened groove 126 is 5 mm, the depth is 2 mm, the center of the widened groove 126 forms a 42-degree angle with line a in the counterclockwise direction, and the distance from the center of the widened groove 126 to the center of the through hole 2 is 26.6 mm. The connection line between the center of the widened groove 126 and the center of the through hole 2 is the center line of the communication groove 129, and the width of the communication groove 129 is 1 mm and the depth is 0.5 mm. The radius of the branch groove 127 is 1.5 mm, the depth is 2 mm, and the center of the branch groove 127 forms a 10-degree angle with line a in the counterclockwise direction.

[0045] Refer to Figure 2 , the upper shell 11 and the lower shell 12 are connected by bolts 13, and a first sealing ring 14 is provided at the connection between the upper shell 11 and the lower shell 12. Threaded holes adapted to the bolts 13 are also provided on the upper shell 11. During operation, the pump shell 1 is composed of the upper shell 11 and the lower shell 12. The upper shell 11 and the lower shell 12 are connected by bolts 13 and a first sealing ring 14 is provided at the connection, which can ensure that the upper shell 11 and the lower shell 12 are closely fitted, avoid leakage at the connection between the upper shell 11 and the lower shell 12 of the pump shell 1, and ensure the sealing performance inside the pump body.

[0046] Refer to Figure 2, on the side of the lower housing 12 away from the upper housing 11, there is a sealing cover 10 adapted to the through hole 2, and a second sealing ring 101 is provided at the connection between the sealing cover 10 and the through hole 2; during operation, the through hole 2 on the pump housing 1 penetrates the entire pump housing 1. Among them, the through hole 2 on the upper housing 11 is made to penetrate the upper housing 11 to facilitate the installation and placement of the transmission shaft 3, and the through hole 2 on the lower housing 12 is made to penetrate the through hole 2, which not only facilitates the installation and positioning of the transmission shaft 3 but also facilitates the discharge of the precipitated grease or impurities in the lower housing 12 during the maintenance of the pump, facilitating the subsequent maintenance.

[0047] Refer to Figures 4 to 6 , the crescent plate 7 and the lower housing 12 are of an integrally formed structure. The outer side wall of the crescent plate 7 is in precise dynamic fit with the teeth of the external gear 4, and the inner side wall of the crescent plate 7 is in precise dynamic fit with the teeth of the internal gear 5; during operation, making the crescent plate 7 and the lower housing 12 into an integrally formed structure can ensure that the crescent plate 7 is in the middle of the eccentric space formed between the external gear 4 and the internal gear 5, so that the inner side wall of the crescent plate 7 fits with the teeth of the internal gear 5 and the outer side wall fits with the teeth of the external gear 4, making the crescent plate 7 firmly fixed and ensuring the stability of the crescent plate 7 during operation.

[0048] Furthermore, the outer side wall of the crescent plate 7 is in precise dynamic fit with the teeth of the external gear 4, and the inner side wall of the crescent plate 7 is in precise dynamic fit with the teeth of the internal gear 5, which can not only ensure a certain pressure difference between the oil inlet hole 124 and the oil outlet hole 125 in the pump body but also make the pressure difference remain stable during the operation of the pump body.

[0049] Refer to Figure 7 , there is a communication hole 9 between the oil inlet groove 122 and the through hole 2, and the lower end position of the communication hole 9 is adapted to the position of the second sealing ring 101; during operation, during normal operation, the internal gear 5 and the external gear 4 rotate counterclockwise. When the internal gear 5 and the external gear 4 rotate clockwise due to a work error, the pressure at the oil inlet hole 124 position in the pump body will gradually increase. When the pressure increases to a certain extent, the liquid in the oil inlet groove 122 will pass through the communication hole 9 downward and break the second sealing ring 101 at the lower end to be discharged, achieving the purpose of breaking the second sealing ring 101 to protect the external gear 4, the internal gear 5 and the entire pump body.

[0050] Finally, through the reasonable design among the components in the pump body, it is ensured that when the pump boosts and conveys the coolant or cutting fluid, no high-pressure area will be formed to cause the temperature of the coolant or cutting fluid to rise, ensuring the stable operation of the pump body. Furthermore, it ensures that the pressure of the coolant or cutting fluid conveyed by the pump body is stable and the flow rate is stable, and at the same time further extends the service life of the pump body itself.

[0051] Embodiment Two:

[0052] After applying a precision internal gear pump of the present invention to the central water outlet pressurizing device for injecting cutting fluid or coolant in machining, the data of pressure, flow rate and aperture are as follows:

[0053]

[0054] It can be seen from the experimental data that by using the above-mentioned precision internal gear pump to increase the pressure of cutting fluid or coolant injection, it can effectively avoid the phenomenon of jamming of the external gear and the internal gear meshing inside the gear pump due to excessive pressure. It adopts a form of multiple pressure relief protections for the meshing part of the external gear and the internal gear in advance to solve the jamming phenomenon caused by excessive pressure at the meshing part of the external gear and the internal gear. This not only ensures that the precision internal gear pump can achieve a large pressure output during operation, but also ensures that when injecting cutting fluid or coolant, the precision internal gear pump has a large pressure, a stable flow rate output, and a stable operation. Compared with the traditional pump that can only reach about 2 MPa, a precision internal gear pump provided by the present invention can increase the pressure to 7 MPa, and can ensure that the external gear and the internal gear inside the gear pump do not jam, realizing a large output pressure, a stable flow rate output, and a stable operation.

[0055] The above is only the preferred embodiment of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the technical principle of the present invention, several improvements and retouches can be made, and these improvements and retouches should also be regarded as the protection scope of the present invention.

Claims

1. A precision internal meshing gear pump, comprising a pump housing (1). A through hole (2) is provided in the middle of the pump housing (1), and a transmission shaft (3) passes through the through hole (2). An external gear (4) is provided in the pump housing (1), and an internal gear (5) is internally meshed with the external gear (4). A shaft hole (6) adapted to the transmission shaft (3) is provided in the middle of the internal gear (5). An eccentricity space is formed between the external gear (4) and the internal gear (5), and a crescent plate (7) is provided in this space. Characterized in that, The teeth of the internal gear (5) are in a straight line form, the teeth of the external gear (4) are in an involute form, and a flow guiding gap (8) is spaced at the meshing portion of the internal gear (5) and the external gear (4); within one rotation period, when the transmission shaft (3) drives the external gear (4) to rotate through the internal gear (5), only on one surface there is a fitting contact surface between the teeth of the internally meshed internal gear (5) and the external gear (4). This fitting contact surface divides the flow guiding gap (8) into two, and each of the two divided flow guiding gaps (8) has no closed section; The pump housing (1) includes an upper housing (11) and a lower housing (12). A gear groove (121) adapted to the external gear (4) is provided inside the lower housing (12). An oil inlet groove (122) and an oil outlet groove (123) connected to the gear groove (121) are further provided inside the lower housing (12). The oil inlet groove (122) is connected to an oil inlet hole (124) on the side wall of the lower housing (12), and the oil outlet groove (123) is connected to an oil outlet hole (125) on the other side wall of the lower housing (12); A widened groove (126) and a branch groove (127) connected to the oil outlet groove (123) are further provided inside the lower housing (12). Among them, the widened groove (126) widens one side of the oil outlet groove (123) close to the meshing portion of the internal gear (5) and the external gear (4), and the branch groove (127) extends the oil outlet groove (123) towards the meshing portion of the external gear (4) and the internal gear (5). A positioning groove (15) and a positioning rod (16) are provided on the lower housing (12).

2. A precision internal meshing gear pump according to claim 1, Characterized in that, A rotating housing (128) adapted to the transmission shaft (3) is provided in the middle of the lower housing (12). A communication groove (129) is further provided inside the lower housing (12), and the communication groove (129) connects the oil outlet groove (123) and the rotating housing (128).

3. A precision internal meshing gear pump according to claim 2, Characterized in that, A communication hole (9) is provided between the oil inlet groove (122) and the through hole (2).

4. A precision internal meshing gear pump according to claim 3, Characterized in that, The upper housing (11) and the lower housing (12) are connected by bolts (13), and a first sealing ring (14) is provided at the connection of the upper housing (11) and the lower housing (12).

5. A precision internal meshing gear pump according to claim 4, Characterized in that, A sealing cover (10) adapted to the through hole (2) is provided on the side of the lower housing (12) away from the upper housing (11), and a second sealing ring (101) is provided at the connection between the sealing cover (10) and the through hole (2).

6. A precision internal meshing gear pump according to claim 5, characterized in that the crescent plate (7) and the lower housing (12) are of an integrally formed structure.

7. A precision internal meshing gear pump according to claim 6, characterized in that the outer side wall of the crescent plate (7) is in precise dynamic fit with the teeth of the external gear (4), and the inner side wall of the crescent plate (7) is in precise dynamic fit with the teeth of the internal gear (5).

8. A precision internal meshing gear pump according to claim 1, characterized in that the upper housing (11) is adapted to the lower housing (12).

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