An internal gear pump with long meshing line and design method thereof

Abstract

The present invention provides an internal gear pump with a long meshing line and a design method, comprising a pump body, an output shaft, an outer rotor, an inner rotor and a crescent plate, wherein the outer rotor is rotatably arranged in the pump body, the inner rotor is coaxially connected to the output rotating shaft, the crescent plate is fixedly installed in the pump body, the outer rotor is arranged on the outer side of the crescent plate, the inner rotor is arranged on the inner side of the crescent plate, the areas of the outer rotor and the inner rotor away from the crescent plate are mutually meshing areas, the inner rotor rotates counterclockwise, the area in the pump body where the outer rotor and the inner rotor gradually disengage their teeth when rotating counterclockwise is set as an oil suction chamber, the area in the pump body where the outer rotor and the inner rotor gradually mesh when rotating counterclockwise is set as an oil pressure chamber, the tooth profile of the outer rotor is set as a cycloid shape, and the tooth profile of the inner rotor is also set as a cycloid shape; during the operation of the internal gear pump, the long meshing line disperses the force to multiple tooth surfaces, reduces the meshing stress, effectively reduces the tooth surface wear, and improves the service life.

Description

Technical Field

[0001] The invention relates to the field of mechanical design, in particular to an internal meshing gear pump with a long meshing line and a design method thereof. Background Art

[0002] A conventional internal gear pump usually includes a pump body and an outer rotor, an inner rotor and a crescent plate arranged in the pump body. The inner rotor is coaxially connected to the drive shaft in the pump body, the outer rotor is rotatably connected in the pump body, the crescent plate is fixedly arranged in the pump body, the outer rotor is arranged around the outside of the crescent plate, and the inner rotor is arranged on the inside of the crescent plate. The outer rotor and the inner rotor are in a mutually meshing state at one end away from the crescent plate, and the outer rotor and the inner rotor are separated by the crescent plate at one end close to the crescent plate. The outer rotor rotates along the outer side of the crescent plate, and the inner rotor rotates along the inner side of the crescent plate.

[0003] The tooth profile of a conventional internal gear pump is an involute tooth profile. The meshing line of the involute internal rotor is short, and the number of meshing teeth is only 1 to 2. The force can only be concentrated on these 1 to 2 tooth surfaces. There are several main problems:

[0004] The first is that the meshing stress of the gear meshing pump increases, which will accelerate the wear of the tooth surface and shorten the service life;

[0005] The second is that the gear meshing pump has internal leakage problems;

[0006] The third is that the gear meshing pump has the phenomenon of "tooth profile overlapping interference" and "transition curve interference". Summary of the invention

[0007] In order to solve the above technical problems, the present invention provides an internal gear pump with a long meshing line and a design method.

[0008] The present invention is achieved through the following technical solutions.

[0009] The present invention provides an internal meshing gear pump with a long meshing line, comprising a pump body, an output shaft, an outer rotor, an inner rotor and a crescent plate. The outer rotor is rotatably arranged in the pump body, the inner rotor is coaxially connected to the output rotating shaft, the crescent plate is fixedly installed in the pump body, the outer rotor is placed on the outside of the crescent plate, the inner rotor is placed on the inside of the crescent plate, the areas of the outer rotor and the inner rotor away from the crescent plate are mutually meshing areas, the inner rotor rotates counterclockwise, the area in the pump body where the outer rotor and the inner rotor gradually lose teeth when rotating counterclockwise is set as an oil suction chamber, and the area in the pump body where the outer rotor and the inner rotor gradually mesh when rotating counterclockwise is set as an oil pressure chamber.

[0010] Preferably, the tooth profile of the outer rotor is arranged in a cycloid shape, and the tooth profile of the inner rotor is also arranged in a cycloid shape.

[0011] Preferably, the tooth top of the outer rotor is in a planar shape, the tooth root of the outer rotor is in a curved shape, and the length of the tooth top of the outer rotor is greater than the length of the tooth root of the outer rotor.

[0012] Preferably, the tooth tops of the inner rotor are arranged to be planar, and the tooth roots of the inner rotor are arranged to be curved.

[0013] Preferably, the tooth profile length of the inner rotor is greater than the tooth profile length of the outer rotor.

[0014] The present invention also provides a design method for an internal gear pump with a long meshing line, comprising the following steps:

[0015] S1: The center of the inner rotor is set to O1, the center of the outer rotor is set to O2, the intersection point of the inner rotor tooth tip circle and the outer rotor tooth tip circle is set to B2, the intersection point of the inner rotor pitch circle and the outer rotor pitch circle is set to P, the arc line between point B2 and point P forms the PB2 arc segment, the perpendicular bisector of the PB2 straight line segment intersects with the O1O2 straight line segment, and the intersection point is set to O';

[0016] S2: Point B1 is set on the tooth tip circle of the outer rotor, and the arc line between point B1 and point P forms a B1P arc segment, and the B1P arc segment and the PB2 arc segment are tangent to point P;

[0017] S3: The center of the B1P arc segment is set to O", the radius of the B1P arc segment is PO", and the center of the PB2 arc segment is also O', satisfying that the length of PO" is equal to the length of O'O2, and the meshing line between the outer rotor and the inner rotor is composed of the B1P arc segment and the PB2 arc segment.

[0018] Preferably, the radii of the inner rotor pitch circle and the outer rotor pitch circle are set to r1 and r2 respectively, and the radius of the PB2 arc segment is set to R, satisfying PO"=r2-R.

[0019] Preferably, the tooth profile of the inner rotor is set to a1Pb1, a1 is set on the inner rotor tooth top circle, b1 is set on the outer rotor tooth top circle, and the inner rotor tooth profile intersects at point P; the tooth profile of the outer rotor is set to a2'a2Pb2, a2' is set on the inner rotor tooth top circle, b2 is set on the outer rotor tooth top circle, and the outer rotor tooth profile intersects at point P; when in the meshing stage of the B1P arc segment, Pb1 in the inner rotor tooth profile and Pb2 in the outer rotor tooth profile produce a conjugate relationship; when in the meshing stage of the PB2 arc segment, a1P in the inner rotor tooth profile and Pb2 in the outer rotor tooth profile produce a conjugate relationship.

[0020] Preferably, in the whole meshing process, only the Pb2 segment of the tooth profile of the outer rotor tooth profile a2'a2Pb2 participates in the meshing, the tooth profile a2P is a symmetrical curve of the tooth profile Pb2 about the point P, and the straight line segment a2'a2 is tangent to the tooth profile a2P at the point a2.

[0021] Preferably, the pressure angle at point P is 0°.

[0022] The beneficial effects of the present invention are:

[0023] 1. The entire structural modulus becomes smaller and the number of teeth is dense, which can reduce the pulsation rate of the internal gear pump, thereby improving the stability of the oil pump pressure and the oil chamber pressure.

[0024] 2. The tooth profiles of the inner rotor and the outer rotor are both cycloid-shaped. There is no overlapping interference of tooth profiles and interference of transition curves. The full height of the tooth is not restricted. At the same time, the pressure angle at the node P is set to 0°. The length of the meshing line is longer than that of the conventional involute gear, and the gap is smaller during the meshing process, which effectively reduces internal leakage.

[0025] 3. During the operation of the internal gear pump, the long meshing line disperses the force to multiple tooth surfaces, reducing the meshing stress, effectively reducing tooth surface wear and increasing service life.

[0026] 4. Compared with the conventional involute, this structure reduces the pulsation rate groove while having a smaller displacement attenuation, thereby reducing the internal leakage of the internal gear pump and increasing the oil flow rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of the structure of the present invention;

[0028] Figure 2 It is a structural schematic diagram of an internal gear pump with a long meshing line for the first set of module and number of teeth data test in the present invention;

[0029] Figure 3 It is a structural schematic diagram of a common involute internal meshing gear pump for the first set of module and tooth number data test in the present invention;

[0030] Figure 4 It is a structural schematic diagram of an internal gear pump with a long meshing line in the second set of module and number of teeth data test in the present invention;

[0031] Figure 5 It is a structural schematic diagram of a common involute internal gear pump for the second set of module and number of teeth data test in the present invention;

[0032] Figure 6 It is a structural schematic diagram of an internal gear pump with a long meshing line in the third group of module and number of teeth data test in the present invention;

[0033] Figure 7 It is a structural schematic diagram of a common involute internal gear pump for the second set of module and number of teeth data test in the present invention;

[0034] Figure 8 It is a schematic diagram of the meshing principle of the outer rotor and the inner rotor in the present invention;

[0035] Fig. 9 It is an enlarged schematic diagram of part I of the present invention;

[0036] In the figure: 1-outer rotor; 2-inner rotor; 3-crescent plate. DETAILED DESCRIPTION

[0037] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0038] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0039] In this embodiment, refer to Figure 1 , including a pump body, an output shaft, an outer rotor 1, an inner rotor 2 and a crescent plate 3, the outer rotor 1 is rotatably arranged in the pump body, the inner rotor 2 is coaxially connected to the output rotating shaft, the crescent plate 3 is fixedly installed in the pump body, the outer rotor 1 is placed on the outside of the crescent plate 3, the inner rotor 2 is placed on the inside of the crescent plate 3, the areas of the outer rotor 1 and the inner rotor 2 away from the crescent plate are mutually meshing areas, the inner rotor 1 rotates counterclockwise, the area in the pump body where the outer rotor 1 and the inner rotor 2 gradually lose teeth when rotating counterclockwise is set as an oil suction chamber, and the area in the pump body where the outer rotor 1 and the inner rotor 2 gradually mesh when rotating counterclockwise is set as an oil pressure chamber.

[0040] The tooth profile of the outer rotor 1 is set to be cycloid, the tooth top of the outer rotor 1 is flat, the tooth root of the outer rotor 1 is curved, and the length of the tooth top of the outer rotor 1 is greater than the length of the tooth root of the outer rotor 1;

[0041] The tooth profile of the inner rotor 2 is also set to be cycloid, the tooth top of the inner rotor 2 is set to be flat, the tooth root of the inner rotor 2 is curved, and the tooth profile length of the inner rotor 2 is greater than the tooth profile length of the outer rotor 1. By setting the tooth profiles of the outer rotor 1 and the inner rotor 2 to be cycloid, there will be no involute interference, tooth profile overlap interference, and transition curve interference, so that the full height of the outer rotor 1 tooth is not limited, and at the same time, the meshing line is extended, the module is reduced, and the number of teeth is increased, thereby reducing the pulsation rate of the internal gear pump, thereby improving the stability of the oil pump pressure and the oil chamber pressure.

[0042] The working principle of this embodiment is as follows: the driving shaft drives the inner rotor 2 to rotate, the inner rotor 2 drives the outer rotor 1 to rotate, and oil is introduced into the oil suction chamber from the outside. Through the rotation of the outer rotor 1 and the inner rotor 2 in the pump body, the oil in the pump body is transmitted to the oil pressure chamber and transmitted out from the oil pressure chamber to realize the oil conversion transmission. The crescent plate has a sealing effect inside the pump body to prevent oil leakage in the pump body.

[0043] In order to more clearly observe the difference between this structure and the conventional involute gear structure, in this embodiment, three groups of experiments are designed, in which the module and the number of teeth are set to variable values, and in each group of experiments, the internal gear pump with a long meshing line and the ordinary involute internal gear pump use the same module and number of teeth, and the displacement values ​​of the internal gear pump with a long meshing line and the ordinary involute internal gear pump are compared, wherein the calculation formula of the displacement is: Unit: L / r;

[0044] Where, d a1 is the diameter of the inner rotor tooth tip circle, in mm;

[0045] d a2 is the outer rotor diameter, in mm;

[0046] h is the rotor thickness, in mm;

[0047] η is the volumetric efficiency, and in engineering it is generally taken as η=0.8~0.9.

[0048] The comparison of different displacements of the long meshing line internal gear pump and the ordinary involute internal gear pump in three groups of tests is shown in Table 1:

[0049] Table 1 Comparison of displacement of two internal gear pumps

[0050]

[0051]

[0052] From the above data, it can be concluded that with the increase of module and number of teeth, the displacement of the long meshing line internal gear pump decays from 0.026L / r to 0.023L / r, a decay of 11.5%, while the displacement of the ordinary involute internal gear pump decays from 0.026L / r to 0.014L / r, a decay of 46.2%. It can be clearly seen from the data that the displacement of the long meshing line internal gear pump has a lower attenuation degree, which can more effectively reduce internal leakage, increase service life, and has a good application prospect.

[0053] In order to meet the above-mentioned specific structural design of the outer rotor tooth profile and the inner rotor tooth profile, the preferred embodiment of the present invention also provides a design method for an internal gear pump with a long meshing line, comprising the following steps:

[0054] S1: Reference Figure 8 , the center of the inner rotor 2 is set to O1, the center of the outer rotor 1 is set to O2, the intersection point of the inner rotor tooth tip circle and the outer rotor tooth tip circle is set to B2, the intersection point of the inner rotor pitch circle and the outer rotor pitch circle is set to P, the arc line between point B2 and point P forms an arc segment PB2, the perpendicular bisector of the straight line segment PB2 intersects with the straight line segment O1O2, and the intersection point is set to O';

[0055] A point B1 is provided on the tooth tip circle of the outer rotor, and the arc line between point B1 and point P forms a B1P arc segment, and the B1P arc segment and the PB2 arc segment are tangent to point P;

[0056] The center of the B1P arc segment is set to O", the radius of the B1P arc segment is PO", and the center of the PB2 arc segment is also O', satisfying that the length of PO" is equal to the length of O'O2, the radii of the inner rotor pitch circle and the outer rotor pitch circle are set to r1 and r2 respectively, and the radius of the PB2 arc segment is set to R, satisfying PO"=r2-R, and the meshing line between the outer rotor 1 and the inner rotor 2 is composed of the B1P arc segment and the PB2 arc segment; the meshing line of the outer rotor 1 and the inner rotor 2 is composed of two arc segments, which is longer than that of conventional involute gears, has a wider meshing surface, and a smaller gap during the meshing process.

[0057] S2: Reference Fig. 9 , the tooth profile of the inner rotor is set to a1Pb1, a1 is set on the inner rotor tooth top circle, b1 is set on the outer rotor tooth top circle, and the inner rotor tooth profiles intersect at point P; the tooth profile of the outer rotor is set to a2'a2Pb2, a2' is set on the inner rotor tooth top circle, b2 is set on the outer rotor tooth top circle, and the outer rotor tooth profiles intersect at point P; when in the meshing stage of the B1P arc segment, Pb1 in the inner rotor tooth profile and Pb2 in the outer rotor tooth profile produce a conjugate relationship ; During the meshing stage of the PB2 arc segment, a1P in the inner rotor tooth profile and Pb2 in the outer rotor tooth profile form a conjugate relationship; in the entire meshing process, only the Pb2 segment tooth profile of the outer rotor tooth profile a2'a2Pb2 participates in the meshing, the tooth profile a2P is the symmetrical curve of the tooth profile Pb2 about point P, and the straight line segment a2'a2 is tangent to the tooth profile a2P at point a2; when the inner rotor 2 and the outer rotor 1 are meshing, the tooth profile overlapping interference and transition curve interference are avoided.

[0058] S3: Point P is a node. When it is at point P, the pressure angle between the outer rotor tooth profile and the inner rotor tooth profile is 0°. The pressure angle gradually increases with the movement of the meshing line, so increasing the number of teeth and reducing the module have little effect on the tooth height, reducing the meshing stress and effectively reducing the tooth surface wear.

[0059] The above are only preferred embodiments of the present invention, and are not intended to limit the patent scope of the present invention. All equivalent structural changes made using the contents of the present invention's specification and drawings, or directly / indirectly applied in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. An internal gear pump with a long meshing line, comprising a pump body, an output shaft, an outer rotor (1), an inner rotor (2) and a crescent plate (3), characterized in that: The outer rotor (1) is rotatably arranged in the pump body, the inner rotor (2) is coaxially connected to the output rotating shaft, the crescent plate (3) is fixedly installed in the pump body, the outer rotor (1) is arranged on the outside of the crescent plate (3), the inner rotor (2) is arranged on the inside of the crescent plate (3), the areas of the outer rotor (1) and the inner rotor (2) away from the crescent plate are mutually meshing areas, the inner rotor (1) rotates counterclockwise, the area in the pump body where the outer rotor (1) and the inner rotor (2) gradually lose teeth when rotating counterclockwise is set as an oil suction chamber, and the area in the pump body where the outer rotor (1) and the inner rotor (2) gradually mesh when rotating counterclockwise is set as an oil pressure chamber.

2. An internal gear pump with a long meshing line as claimed in claim 1, characterized in that: The tooth profile of the outer rotor (1) is arranged in a cycloid shape, and the tooth profile of the inner rotor (2) is also arranged in a cycloid shape.

3. An internal gear pump with a long meshing line as claimed in claim 1, characterized in that: The tooth top of the outer rotor (1) is in a plane shape, the tooth root of the outer rotor (1) is in a curved surface shape, and the length of the tooth top of the outer rotor (1) is greater than the length of the tooth root of the outer rotor (1).

4. An internal gear pump with a long meshing line as claimed in claim 1, characterized in that: The tooth top of the inner rotor (2) is arranged in a plane shape, and the tooth root of the inner rotor (2) is in a curved surface shape.

5. An internal gear pump with a long meshing line as claimed in claim 1, characterized in that: The tooth profile length of the inner rotor (2) is greater than the tooth profile length of the outer rotor (1).

6. A method for designing an internal gear pump with a long meshing line as claimed in any one of claims 1 to 5, characterized in that: The following steps are involved: S1: The center of the inner rotor (2) is set to O1, the center of the outer rotor (1) is set to O2, the intersection point of the inner rotor tooth tip circle and the outer rotor tooth tip circle is set to B2, the intersection point of the inner rotor pitch circle and the outer rotor pitch circle is set to P, the arc line between point B2 and point P forms an arc segment PB2, the perpendicular bisector of the PB2 straight line segment intersects with the O1O2 straight line segment, and the intersection point is set to O'; S2: Point B1 is set on the tooth tip circle of the outer rotor, and the arc line between point B1 and point P forms a B1P arc segment, and the B1P arc segment and the PB2 arc segment are tangent to point P; S3: The center of the B1P arc segment is set to O", the radius of the B1P arc segment is PO", and the center of the PB2 arc segment is O', so that the length of PO" is equal to the length of O'O2, and the meshing line between the outer rotor (1) and the inner rotor (2) is composed of the B1P arc segment and the PB2 arc segment.

7. The design method of a long meshing line internal gear pump according to claim 6, characterized in that: The radii of the inner rotor pitch circle and the outer rotor pitch circle are set to r1 and r2 respectively, and the radius of the PB2 arc segment is set to R, satisfying PO"=r2-R.

8. The design method of a long meshing line internal gear pump according to claim 6, characterized in that: The tooth profile of the inner rotor is set as a1Pb1, a1 is set on the inner rotor tooth top circle, b1 is set on the outer rotor tooth top circle, and the inner rotor tooth profiles intersect at point P; the tooth profile of the outer rotor is set as a2'a2Pb2, a2' is set on the inner rotor tooth top circle, b2 is set on the outer rotor tooth top circle, and the outer rotor tooth profiles intersect at point P; when in the meshing stage of the B1P arc segment, Pb1 in the inner rotor tooth profile and Pb2 in the outer rotor tooth profile produce a conjugate relationship; When in the meshing stage of the PB2 arc segment, a1P in the inner rotor tooth profile and Pb2 in the outer rotor tooth profile produce a conjugate relationship.

9. The design method of a long meshing line internal gear pump according to claim 8, characterized in that: During the entire meshing process, of the outer rotor tooth profile a2'a2Pb2, only the Pb2 segment tooth profile participates in the meshing. The tooth profile a2P is a symmetrical curve of the tooth profile Pb2 about point P, and the straight line segment a2'a2 is tangent to the tooth profile a2P at point a2.

10. The design method of a long meshing line internal gear pump according to claim 6, characterized in that: The pressure angle at point P is 0°.

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