Internal gear pump

Abstract

An internal gear pump includes a pump body. An internal gear ring is arranged in the pump cavity of the pump body. A driving gear is arranged inside the internal gear ring. The internal gear ring is offset relative to the driving gear. A positioning rod is arranged on the outer side of the biting-in side at the meshing position between the driving gear and the internal gear ring. A floating sealing device is arranged between the meshing position and the positioning rod. The sealing device includes a crescent main board, a crescent sub-board, a spring piece, and a sealing rod. Three through holes are arranged on the inner side surface of the crescent main board at two-fifths of the arc length. The included angle between the axial center line of the through hole and the normal line of the inner side surface is 24.68°, and it is inclined towards the positioning rod side. The diameter of the through hole is 0.52 mm. Due to the through holes arranged on the crescent main board, it ensures that the pressure difference between the inner and outer side surfaces of the crescent main board is appropriate, which is beneficial to significantly delaying the uniform wear of the inner side surface of the crescent main board and the deformation of the sealing rod, thereby effectively extending the service life of the internal gear pump.

Description

Technical Field

[0001] The present invention relates to a hydraulic pump, and more specifically, to an internal gear pump for outputting high-pressure hydraulic oil. Background Art

[0002] In the existing internal gear pump, a crescent main plate and a crescent sub-plate divide the cavity in the pump body into a high-pressure hydraulic area and a low-pressure hydraulic area. The high-pressure hydraulic area is located on the side of the crescent main and sub-plates facing the meshing part, and the other side opposite to the crescent main and sub-plates is the low-pressure hydraulic area. A plurality of elastic sealing mechanisms composed of sealing rods and spring pieces are connected between the crescent main plate and the crescent sub-plate. During actual use, it is found that the inner contact surface between the crescent main plate and the inner side of the driving gear wears relatively fast, and the sealing rod also undergoes unexpected deformation and fails, resulting in premature damage of the internal gear pump. Summary of the Invention

[0003] To overcome the above defects, the technical problem to be solved by the present invention is to provide an internal gear pump that can improve the pressure difference between the inner and outer sides of the crescent main plate, thereby delaying the wear of the inner side surface of the crescent main plate and the deformation of the sealing rod, and thus extending the service life.

[0004] The technical solution adopted by the present invention to solve the problems existing in the prior art is: an internal gear pump, which includes a hollow pump body. A rotatable annular internal gear ring is provided in the pump cavity of the pump body. A driving gear meshing with the internal gear ring is provided inside the internal gear ring. The outer diameter of the driving gear is smaller than the inner diameter of the internal gear ring. The axial center of the internal gear ring is offset relative to the axial center of the driving gear. A positioning rod fixedly connected to the pump body is provided outside the biting side of the meshing part between the driving gear and the internal gear ring. A floating sealing device is provided between the meshing part and the positioning rod. The sealing device includes a crescent main plate and a crescent sub-plate. One end of the crescent main plate close to the positioning rod is pivotally connected to the pump body through a pin shaft. The inner side surface of the crescent main plate close to the driving gear is arc-shaped and adapted to the outer peripheral surface of the driving gear. The outer side surface of the crescent sub-plate away from the crescent main plate is circular-arc-shaped and adapted to the inner peripheral surface of the internal gear ring. A plurality of elastic sealing mechanisms are provided between the outer side surface of the crescent main plate close to the crescent sub-plate and the inner side surface of the crescent sub-plate close to the crescent main plate. At least one through hole is provided between the inner and outer side surfaces of the crescent main plate. The ratio of the arc length of the position of the through hole on the inner side surface of the crescent main plate to the total arc length of the inner side surface of the crescent main plate is between one-fourth and one-half. The included angle between the axial center line of the through hole and the normal line at the position of the through hole on the inner side surface of the crescent main plate is between 20° and 30°. The axial center line of the through hole is inclined towards the positioning rod side relative to the normal line. The total cross-sectional area of the through hole is between 0.4 and 2 square millimeters.

[0005] Multiple inner seal areas are formed between the tooth grooves of the driving gear and the inner side surface of the crescent main plate. An elastic sealing mechanism composed of a sealing rod and a spring plate divides the gap between the crescent main plate and the crescent auxiliary plate into multiple outer seal areas. Since there will inevitably be some small amount of internal leakage of oil in the hydraulic pump, the oil pressure in the inner and outer seal areas close to the low-pressure hydraulic area increases successively to the inner and outer seal areas close to the high-pressure hydraulic area; because the time for the inner seal area to transfer from the low-pressure hydraulic area to the high-pressure hydraulic area is extremely short and the amount of internally leaked oil obtained is less, the oil pressure in the inner seal area is relatively low; while the outer seal area is fixed and continuously obtains more internally leaked oil, so the oil pressure in the outer seal area is relatively high. Based on these actual phenomena, the inventor uses the lever principle to find the balance point on the inner side surface of the crescent main plate according to the gradient of the oil pressure increase in each inner seal area, and confirms that the position of the balance point on the inner side surface of the crescent main plate is within the range of one-fourth to one-half of the ratio of the arc length of the inner side surface of the crescent main plate near the positioning rod end to the total arc length of the inner side surface of the crescent main plate, that is, the outlet position of the through hole on the inner side surface of the crescent main plate is within this range. Similarly, the inventor uses the lever principle to find the balance point on the outer side surface of the crescent main plate according to the gradient of the oil pressure increase in each outer seal area. The connection line between the balance points on the inner and outer side surfaces of the crescent main plate is the axial center line of the through hole. For the convenience of making the through hole, it is confirmed that the axial center line of the through hole is inclined towards the positioning rod side with respect to the normal line of the position of the through hole on the inner side surface of the crescent main plate, and the included angle with this normal line is between 20° and 30°. If the pressure difference between the inner and outer side surfaces of the crescent main plate is too large, it will cause premature wear and damage to the inner side surface of the crescent main plate, and the sealing rod will also be deformed and damaged in advance; if the pressure difference between the inner and outer side surfaces of the crescent main plate is too small, it will cause unreliable sealing between the crescent main plate and the tooth tip of the driving gear, excessive oil backflow in the high-pressure hydraulic area, reducing the working efficiency of the internal gear pump, and in severe cases, it may even cause the working pressure of the internal gear pump not to reach the rated pressure; determining whether the pressure difference between the inner and outer side surfaces of the crescent main plate is appropriate depends on the total oil flow generated by the number and diameter of the through holes. Therefore, the inventor calculates the total cross-sectional area of the through holes according to relevant parameters = 0.6291 mm2; where the total flow rate Q of the through holes = k b , k: system error correction coefficient, : pressure difference at both ends of the through hole = - ( generally takes 0.1~0.2 MPa), is the pressure at the balance point position on the inner side surface of the crescent main plate, is the pressure at the balance point position on the outer side surface of the crescent main plate, Absolute viscosity, l: length of the through-hole, b: width of the driving gear, h: clearance on the side of the crescent main board, : linear velocity of the outermost circle of the driving gear. Considering the sealing reliability between the crescent main board and the tooth tip of the driving gear, the total cross-sectional area S of the through-hole is taken to be between 0.4 and 2 square millimeters.

[0006] As a further technical solution, the ratio of the arc length of the position of the through-hole on the inner side of the crescent main board to the inner side of the crescent main board near one end of the positioning rod to the total arc length of the inner side of the crescent main board is between seven twentieths and nine twentieths.

[0007] As a further technical solution, the ratio of the arc length of the position of the through-hole on the inner side of the crescent main board to the inner side of the crescent main board near one end of the positioning rod to the total arc length of the inner side of the crescent main board is two fifths.

[0008] As a further technical solution, the angle between the axial center line of the through-hole and the normal line is between 23° and 26°.

[0009] As a further technical solution, the angle between the axial center line of the through-hole and the normal line is between 24° and 25°. In the optimal technical solution, the angle between the axial center line of the through-hole and the normal line is 24.68°.

[0010] As a further technical solution, the total cross-sectional area of the through-hole is between 0.5 and 1 square millimeter.

[0011] As a further technical solution, the total cross-sectional area of the through-hole is between 0.5 and 0.7 square millimeter. In the optimal technical solution, the total cross-sectional area of the through-hole is 0.6371 square millimeter, that is, the diameter of the through-hole is 0.52 millimeter.

[0012] As a further technical solution, the number of the through-holes is 3, and the 3 through-holes are arranged at equal intervals, and the through-hole arranged in the middle is located in the middle of the width of the crescent main board. This is beneficial to the uniformity of the pressure difference on both sides of the crescent main board.

[0013] As a further technical solution, a process hole is provided at one end of the through-hole, and the diameter of the process hole is larger than the diameter of the through-hole. This can reduce the reaming depth of the through-hole, reduce the risk of the reaming drill bit breaking, and thus reduce the manufacturing cost.

[0014] As a further technical solution, the process hole is located at one end of the through-hole facing the inner side of the crescent main board, and the diameter of the process hole is larger than the thickness of the tooth tip of the driving gear. This can effectively avoid the blockage of the through-hole by the tooth tip of the driving gear when passing through the through-hole, and ensure the smooth flow of the oil in the through-hole.

[0015] Beneficial effects: Since through holes are provided between the inner and outer sides of the crescent main board, and the openings of the through holes on the inner and outer sides of the crescent main board are exactly located at the balance points of the inner and outer sides of the crescent main board. At the same time, the appropriate flow rate through the through holes makes the pressure difference between the inner and outer sides of the crescent main board just ensure the effective seal between the inner side of the crescent main board and the tooth tip of the driving gear, without generating excessive pressure. This is beneficial to significantly delaying the uniform wear of the inner side of the crescent main board and the deformation of the sealing rod, thereby effectively extending the service life of the internal gear pump. Description of the drawings

[0016] Figure 1 It is a schematic structural diagram of one embodiment of the present invention.

[0017] Figure 2 is Figure 1 An enlarged schematic view of the R part in

[0018] Figure 3 is Figure 2 An enlarged schematic view of the M part in

[0019] Figure 4 It is a schematic structural diagram of the crescent main board in the present invention.

[0020] In the figure: pump body 1, internal gear ring 2, low-pressure hydraulic area 3, positioning rod 4, crescent sub-board 5, crescent main board 6, high-pressure hydraulic area 7, driving gear 8, pin shaft 9, through hole 10, outer sealing area 11, inner sealing area 12, round convex 13, sealing rod 14, spring piece 15, process hole 16. Specific embodiments

[0021] The present invention will be further described below through specific embodiments in conjunction with the drawings.

[0022] Embodiment: An internal gear pump, as shown in the figure, includes a hollow pump body 1. Inside the pump cavity of the pump body 1, there is a rotatable annular internal gear ring 2. Inside the internal gear ring 2, there is a driving gear 8 that meshes with the internal gear ring 2. The outer diameter of the driving gear 8 is smaller than the inner diameter of the internal gear ring 2. The axial center of the internal gear ring 2 is offset relative to the axial center of the driving gear 8. Outside the biting side of the meshing part between the driving gear 8 and the internal gear ring 2, there is a positioning rod 4 fixedly connected to the pump body 1. Between the meshing part and the positioning rod 4, there is a floating sealing device. The sealing device divides the cavity inside the pump body 1 into a high-pressure hydraulic area 7 and a low-pressure hydraulic area 3. The high-pressure hydraulic area 7 is located on the side of the sealing device facing the meshing part of the driving gear 8 and the internal gear ring 2, and the other side opposite to the sealing device is the low-pressure hydraulic area 3. The sealing device includes a crescent main board 6 and a crescent sub-board 5. One end of the crescent main board 6 close to the positioning rod 4 is pivotally connected to the pump body 1 through a pin shaft 9. One end of the crescent sub-board 5 abuts against the positioning rod 4. The inner side of the crescent main board 6 close to the driving gear 8 is arc-shaped and adapted to the outer peripheral surface of the driving gear 8. Multiple inner sealing areas 12 are formed between the tooth grooves of the driving gear 8 and the inner side surface of the crescent main board 6. The outer side surface of the crescent sub-board 5 away from the crescent main board 6 is arc-shaped and adapted to the inner peripheral surface of the internal gear ring 2. Between the outer side surface of the crescent main board 6 close to the crescent sub-board 5 and the inner side surface of the crescent sub-board 5 close to the crescent main board 6, there are multiple elastic sealing mechanisms. The elastic sealing mechanisms divide the gap between the crescent main board 6 and the crescent sub-board 5 into multiple outer sealing areas 11. The elastic sealing mechanism is jointly composed of a sealing rod 14 and a spring piece 15. There are 3 through holes 10 arranged equidistantly between the inner and outer side surfaces of the crescent main board 6. The middle one of the 3 through holes 10 is located in the middle of the width of the crescent main board 6. The arc length of the position of the through hole 10 on the inner side surface of the crescent main board 6 from the inner side surface of the end of the crescent main board 6 close to the positioning rod 4 to the total arc length of the inner side surface of the crescent main board 6 is two-fifths. The included angle between the axial center line of the through hole 10 and the normal line at the position of the through hole 10 on the inner side surface of the crescent main board 6 is 24.68°. The axial center line of the through hole 10 is inclined towards the positioning rod 4 relative to the normal line. The diameter of the through hole 10 is 0.52 mm. One end of the through hole 10 facing the inner side surface of the crescent main board 6 is provided with a process hole 16. The diameter of the process hole 16 is larger than the thickness of the tooth tip of the driving gear 8. In order to effectively increase the contact area between the sealing rod 14 and the crescent main board 6, thereby improving the contact stress of the sealing rod 14, extending the service life of the sealing rod 14, and ensuring the sealing effectiveness of the outer sealing area 11 of the crescent main board 6, a circular convex 13 that lifts outwards is provided at the position of the sealing rod 14 in the outer sealing area 11 of the crescent main board 6.

[0023] The above-described embodiments are only a preferred solution of the present invention, and do not impose any form of limitation on the present invention. There are other variations and modifications without exceeding the technical solutions recorded in the claims.

[0024] The content not described in detail in this specification belongs to the prior art well known to those skilled in the art.

Claims

1. An internal gear pump, which comprises a hollow pump body. A rotatable annular internal gear ring is arranged in the pump cavity of the pump body. A driving gear meshing with the internal gear ring is arranged inside the internal gear ring. The outer diameter of the driving gear is smaller than the inner diameter of the internal gear ring. The axial center of the internal gear ring is offset relative to the axial center of the driving gear. A positioning rod fixedly connected with the pump body is arranged on the outer side of the biting-in side at the meshing position between the driving gear and the internal gear ring. A floating sealing device is arranged between the meshing position and the positioning rod. The sealing device comprises a crescent main plate and a crescent sub-plate. One end of the crescent main plate close to the positioning rod is pivotally connected to the pump body through a pin shaft. The inner side surface of the crescent main plate close to the driving gear is arc-shaped and adapted to the outer peripheral surface of the driving gear. The outer side surface of the crescent sub-plate away from the crescent main plate is circular-arc-shaped and adapted to the inner peripheral surface of the internal gear ring. A plurality of elastic sealing mechanisms are arranged between the outer side surface of the crescent main plate close to the crescent sub-plate and the inner side surface of the crescent sub-plate close to the crescent main plate. It is characterized in that, There are through holes provided between the inner and outer sides of the crescent main board. The number of the through holes is 3, and the 3 through holes are arranged at equal intervals. Among them, the through hole arranged in the middle is located at the middle of the width of the crescent main board. The arc length of the position of the through hole on the inner side of the crescent main board from the inner side near the positioning rod end of the crescent main board to the total arc length of the inner side of the crescent main board is between one-fourth and one-half. The included angle between the axial center line of the through hole and the normal line at the position of the through hole on the inner side of the crescent main board is between 23° and 26°. The axial center line of the through hole inclines towards the positioning rod side relative to the normal line. The total cross-sectional area of the through hole is between 0.5 and 1 square millimeter.

2. The internal gear pump according to claim 1, characterized in that, The ratio of the arc length of the position of the through hole on the inner side of the crescent main board from the inner side near the positioning rod end of the crescent main board to the total arc length of the inner side of the crescent main board is between seven-twentieths and nine-twentieths.

3. The internal gear pump according to claim 2, characterized in that, The ratio of the arc length of the position of the through hole on the inner side of the crescent main board from the inner side near the positioning rod end of the crescent main board to the total arc length of the inner side of the crescent main board is two-fifths.

4. The internal gear pump according to claim 1, characterized in that, The included angle between the axial center line of the through hole and the normal line is between 24° and 25°.

5. The internal gear pump according to claim 1, characterized in that, The total cross-sectional area of the through hole is between 0.5 and 0.7 square millimeter.

6. The internal gear pump according to any one of claims 1 to 5, characterized in that, One end of the through hole is provided with a process hole, and the diameter of the process hole is larger than the diameter of the through hole.

7. The internal gear pump according to claim 6, characterized in that, The process hole is located at one end of the through hole facing the inner side of the crescent main board, and the diameter of the process hole is larger than the thickness of the top of the driving gear tooth.

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