JP6068580B2 - Pump rotor - Google Patents

Description

  The present invention relates to a pump rotor that can increase the discharge amount and improve the durability without increasing the outer diameter and axial thickness of the rotor.

  In rotors such as trochoid type gears used in conventional internal gear pumps such as oil pumps, the number of teeth is almost limited by specifications such as the root diameter of the inner rotor and the amount of eccentricity with the outer rotor. Therefore, the number of teeth can be increased or decreased only within a narrow range. In addition, when the above-described root diameter, eccentric amount, and number of teeth are determined, the theoretical discharge amount is almost determined.

  In the conventional trochoid rotor, in order to increase the theoretical discharge amount, the eccentric amount between the inner rotor and the outer rotor is increased and the rotor diameter is increased, or the eccentric amount and the rotor diameter are left as they are. A method of increasing the thickness is taken. However, in either method, the rotor size becomes large, which causes a deterioration of friction.

Patent Document 1 exists as an example for solving such a problem. The contents of Patent Document 1 will be outlined. First, the rotor must have a higher degree of freedom in setting the tooth height and increase the theoretical discharge rate of the pump. The plurality of ellipses that create the tooth profile are appropriately combined with ellipses of an appropriate size so that teeth having a tooth height larger than the inner rotor using the tooth profile of the cycloid curve or the trochoid curve are created.

  As described above, the inner rotor has a tooth profile of the tooth tip portion, the tooth bottom portion, and the meshing portion with the outer rotor (portion connecting the tooth tip portion and the tooth bottom portion), respectively, along a curve along the major axis of the ellipse ( An ideal tooth profile can be created by creating a curve with a larger radius of curvature.

  In the tooth profile of FIG. 4 disclosed in Patent Document 1, both the tooth tip portion 2a and the tooth bottom portion 2b are formed by curves along the major axis of the ellipse. Therefore, the contact area | region of the tooth tip with respect to the tooth | gear of an outer rotor and a tooth root can be expanded, and the protection effect of a tooth tip and a tooth bottom increases. Further, as shown in FIG. 4 disclosed in Patent Document 1, it is possible to sufficiently increase the tooth height h by forming the meshing portion 2c with a curve along the long axis of the ellipse.

The rotor of the internal gear pump in Patent Document 1 is compared with the rotor of a general trochoid curve. FIG. 12 disclosed in Patent Document 1 is a pump rotor in which an inner rotor having 8 teeth and an outer rotor having 9 teeth are combined.
The specifications of the tooth profile of Patent Document 1 are shown below.
Outer rotor outer diameter: φ60.0mm
Outer rotor large diameter (tooth root circular diameter): φ52.0mm
Outer rotor small diameter (tooth circle diameter): φ38.4mm
Inner rotor large diameter (tooth diameter): φ45.2mm
Inner rotor small diameter (tooth root circular diameter): φ31.6mm
Inner rotor inner diameter: φ15.0mm
Rotor thickness: 15mm
Eccentricity e: 3.4 mm (Tooth height 2e: 6.8 mm)
The theoretical discharge amount of Patent Document 1 is 12.3 cm ³ / rev.

As a comparative product with respect to Patent Document 1, a pump rotor having a tooth profile of a trochoid curve shown in FIG. 15 disclosed in Patent Document 1 was adopted. FIG. 15 disclosed in Patent Document 1 is disclosed as a pump rotor having a conventional tooth profile. The specifications of this comparative product are as follows.
Outer rotor outer diameter: φ60.0mm
Outer rotor large diameter: φ52.0mm
Outer rotor small diameter: φ39.6mm
Inner rotor large diameter: φ45.8mm
Inner rotor small diameter: φ33.4mm
Rotor thickness: 15mm
Eccentricity e: 3.1 mm (Tooth height 2e: 6.2 mm)
The theoretical discharge amount of this comparative product is 11.4 cm ³ / rev.
As described above, the rotor of Patent Document 1 is extended inward longer than the comparative product to increase the tooth height. And the theoretical discharge amount is increasing.

JP 2011-17318 A

  As described above, Patent Document 1 discloses a rotor having a larger tooth height and an increased theoretical discharge amount. Then, in order to increase the tooth height, the tooth shapes of the tooth tip portion, the tooth bottom portion, and the meshing portion are created by curves along the major axis of the ellipse, respectively, thereby forming an ideal tooth shape. However, since the tooth profile is formed by an ellipse smaller than the molded tooth profile, the partially overlapping ellipses are connected at an angle of approximately 90 °. Near the inflection point, the radius of curvature becomes small, causing a sudden change in shape and not very smooth.

  Since the tooth angle of the meshing portion is increased by increasing the tooth height, the meshing range is reduced in meshing with the outer rotor, and the force pushing the outer rotor is concentrated, and the surface pressure is concentrated. And the outer rotor is driven in a state where the sliding element is large, the durability becomes low. Further, since the portion where the tooth tip of the inner rotor and the tooth bottom of the outer rotor are close to each other is large in the deepest meshing portion, the oil becomes a bag path when the oil is discharged, resulting in a large pumping loss.

  Furthermore, the noise when the rotor meshes tends to be loud, and it cannot be said that the silence is good. An object of the present invention (technical problem to be solved) is an oil pump rotor capable of increasing the discharge amount and improving the durability without increasing the outer diameter or axial thickness of the rotor. Is to provide.

  In view of the above, the inventor has intensively studied to solve the above-mentioned problems. As a result, the invention of claim 1 can be applied to the tooth profile of the inner rotor of the internal gear type pump by an ellipse constituting the half tooth region of the tooth profile. There are three tooth forming circles, and two of these tooth forming circles, one of which is a small tooth forming circle and inscribed in the other large tooth forming circle, the small tooth forming circle. In the half tooth region, a tip portion is formed by a part of the small tooth forming circle, and the small tooth forming circle is inscribed and includes one of the large tooth forming circles. A meshing portion is formed at a portion, a tooth bottom portion is formed by a part of the other tooth forming circle circumscribing the large tooth forming circle, and the large tooth forming circle is formed by the small tooth forming circle. The teeth The small tooth forming circle is included in the large tooth forming circle so that a part of the small tooth forming circle is in contact with the inside of the large tooth forming circle. The above problem was solved by using a pump rotor.

  According to a second aspect of the present invention, in the tooth profile of the inner rotor of the internal gear pump, there are four tooth-forming circles that are ellipses constituting the half-tooth region of the tooth profile, The two tooth-forming circles are two combinations that include the whole of the small tooth-forming circle while inscribed in the other large tooth-forming circle with one being a small tooth-forming circle. A tooth tip portion is formed by a part of the first set of small tooth forming circles, a tooth root portion is formed by a part of the second set of small tooth forming circles, and the other two large tooth forming shapes. The half-tooth region meshing portion is formed while part of the circle is circumscribed, and the large tooth-forming circle is sized to include the tooth profile of the tip portion formed by the small tooth-forming circle. The small tooth forming circle is By the pump rotor formed by inclusion in tooth shaped circle entire small tooth shaped yen is large so as partially to contact the inside of the large tooth shaped circle, the above-mentioned problems are eliminated.

  In the pump rotor according to the invention of claim 1, the number of teeth can be increased without changing the tip diameter, the root diameter, and the eccentric amount, that is, without increasing the tooth height, as compared with a normal trochoid type rotor. The discharge amount can be increased without increasing the outer diameter or axial thickness of the rotor.

  Furthermore, by increasing the number of teeth, a low noise pump rotor with small pulsation is obtained. Further, by inscribed the ellipse, the radius of curvature can be increased in the vicinity of the inflection point of the joint portion between the arc of the tooth tip and the arc of the meshing portion, and the joint portion can be made smooth. Further, since the angle of the teeth of the meshing portion is laid down, the meshing range becomes large in meshing with the outer rotor, the force pushing the outer rotor can be dispersed, and the surface pressure can be kept low.

  And since the outer rotor is driven in a state where the rolling element is larger than the sliding, the durability is improved, and the portion where the tooth tip of the inner rotor and the tooth bottom of the outer rotor are close to each other at the deepest engagement portion is small. The oil can be pushed out efficiently when the oil is discharged, the pumping loss is reduced, the sound when the rotor is engaged can be reduced, and the silence is also improved. The pump rotor drawn in the present invention is the same size as the rotor drawn in a normal trochoid curve, so the size of the rotor storage chamber of the housing does not change, and it can be easily changed to a rotor with a large theoretical discharge amount. Can do.

  In the invention of claim 2, the tooth forming circle is 4, and one of the combinations of the two tooth forming circles is included as a small tooth forming circle while being partially in contact with the other tooth forming circle. In the half tooth region, the tooth bottom region is formed by a part of the small tooth forming circle, so that the tooth profile can be formed with higher accuracy.

(A) is a front view of the inner rotor in the pump rotor according to the first embodiment of the present invention, (B) is an enlarged view of part (A) of (A), and (C) is a tooth profile of the inner rotor in the first embodiment. The state figure which combined the oval tooth formation circle and the small tooth formation circle which comprise, (D) thru | or (F) is a figure which shows the process in which the half-tooth area | region of the tooth profile of the inner rotor in 1st Embodiment is shape | molded. is there. (A) is a state diagram in which an elliptical tooth forming circle and a small tooth forming circle constituting the tooth profile of the inner rotor in the second embodiment of the present invention are combined, and (B) and (C) are in the second embodiment. It is a figure which shows the process until a tooth profile is shape | molded from the half-tooth area | region of the tooth profile of an inner rotor. (A) is a state diagram in which a perfect circular tooth forming circle and a small tooth forming circle constituting the tooth profile of the inner rotor in the other embodiment 1 are combined, and (B) and (C) are inner diagrams in the other embodiment 1. It is a figure which shows the process until a tooth profile is shape | molded from the half-tooth area | region of the tooth profile of a rotor. (A) is a state diagram in which oval and true circular tooth forming circles and small tooth forming circles constituting the tooth profile of the inner rotor in other embodiment 2 are combined, and (B) and (C) are other embodiments. It is a figure which shows the process until a tooth profile is shape | molded from the half-tooth area | region of the tooth profile of the inner rotor in 2. FIG. It is the figure which compared the tooth profile of the inner rotor of this invention with the tooth profile of the normal trochoid type inner rotor. It is an example of the pump rotor of the present invention, and is a diagram in which an inner rotor having 8 teeth and an outer rotor having 9 teeth are combined. FIG. 2 is a diagram of a conventional trochoidal curve pump rotor for comparison with the present invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The pump rotor of the present invention is a gear-shaped rotor constituting an internal gear pump. This type is generally a combination of an inner rotor and an outer rotor that rotates with the inner rotor disposed inward.

  The present invention relates to a pump rotor, and mainly relates to an inner rotor. Hereinafter, the inner rotor will be mainly described in the pump rotor. FIG. 5 is a comparison of the tooth profile A of the pump rotor (inner rotor) according to the present invention and the tooth profile B of the inner rotor drawn by a normal trochoid curve. The tooth profile A of the present invention and the tooth profile B made of a trochoid curve are arranged at the same position.

  The tooth tip circle Ja and the root circle Jb are the same in the tooth profile A of the pump rotor (inner rotor) drawn in the present invention and the tooth profile B of the inner rotor drawn in a normal trochoid curve. That is, the tooth tip diameter and the tooth root diameter do not change, and the pitch angle of one tooth (from the top of the tooth root to the top of the tooth bottom) is the pitch angle of one tooth of the pump rotor drawn in the present invention. When the pitch angle of one tooth of the inner rotor drawn by a normal trochoid curve is θb, “θb> θa” is satisfied.

  By making the tip circle Ja and the root circle Jb the same as the inner rotor of a normal trochoid curve, the number of teeth can be easily increased while maintaining the same amount of eccentricity. Therefore, there is no change in the sizes of the pump rotor (inner rotor) and the outer rotor of the present invention, and the center positions of each do not change. In other words, the outer diameter of the outer rotor does not increase, and it can be easily applied to a pump without changing the size and axial position of the rotor storage chamber of the housing using the rotor drawn with a normal trochoid curve. And the theoretical discharge amount can be increased.

  Next, a drawing for the tooth profile A of the pump rotor (inner rotor) of the present invention to be “θb> θa” and the tip circle Ja and the root circle Jb to be the same as the inner rotor of a normal trochoidal curve. A method will be described. The half-tooth region A1 is composed of a plurality of large and small tooth forming circles (large tooth forming circle C, small tooth forming circle Cs). The half-tooth region A1 refers to a portion on one side divided into two regions so that the tooth tip portion 1 is symmetric with respect to the diameter direction line Lc passing through the diameter center P of the pump rotor. That is, the tooth profile A is formed by the left and right symmetrical half-tooth regions A1, A1.

  The plurality of tooth forming circles C and Cs is a combination of at least three. Furthermore, in two of these tooth forming circles, one part is in contact with the other large tooth forming circle C as a small tooth forming circle Cs, and a small tooth forming circle Cs is formed in the large tooth forming circle C. Combined to be included. A tooth tip portion of the half tooth region A1 of the tooth profile A is formed by a part of the small tooth forming circle Cs, and a part of the other large tooth forming circle C is smoothly joined to each other to form the half tooth region A1. Formed from the tooth tip to the tooth bottom.

  Further, in the case where the half-tooth region A1 is composed of four large and small tooth forming circles C and Cs, the small tooth profile which is included while partly contacting the large tooth forming circle C and the large tooth forming circle C. There are two combinations with the forming circle Cs. One of the two small tooth-forming circles Cs constitutes the tooth tip of the half-tooth region A1, and the other small tooth-forming circle Cs constitutes the tooth bottom of the half-tooth region A1.

  The large and small tooth forming circles C and Cs have an ellipse. In the present invention, the large and small tooth forming circles C and Cs have a plurality of embodiments shown below by a combination of ellipses. First, in the first embodiment, the plurality of large and small tooth forming circles C and Cs constituting the half-tooth region A1 are composed of a combination of only ellipses (see FIG. 1).

  The half-tooth region A1 is composed of three tooth-forming circles C, and the large and small tooth-forming circles C and Cs are all elliptical (see FIGS. 1B, 1C, etc.). As described above, in the three tooth forming circles, one is a small tooth forming circle Cs, which is smaller than other large tooth forming circles C. The plurality of (three) tooth forming circles C (including the small tooth forming circle Cs) constitute the tooth tip portion 1, the meshing portion 2, and the tooth bottom portion 3 of the half tooth region A1.

  In the first embodiment, the three oval large and small tooth forming circles C and Cs used are the same as the other two large tooth forming circles C except for the small tooth forming circle Cs. The first tooth-forming circle C1 and the second tooth-forming circle C2 that are elliptical (see FIG. 1C). And in the tooth tip part 1 of half-tooth area | region A1, a part of small tooth formation circle Cs is used. In the meshing portion 2, a part of each of the first tooth forming circle C1 and the second tooth forming circle C2 is used continuously. The other part of the second tooth forming circle C2 is used for the tooth bottom part 3.

  The small tooth forming circle Cs is included so as to partially contact the first tooth forming circle C1. That is, a small tooth formation circle Cs is arranged inside the elliptical first tooth formation circle C1, and a part of both ellipses are in contact with each other. The first tooth forming shape circle C1 is larger than the tooth shape to be formed. That is, it is an ellipse that substantially encloses the tooth profile outline and projects outward.

  Since the small tooth forming circle Cs constituting the tooth tip portion 1 is in contact with the inside of the first tooth forming circle C 1, the shape locus of the tooth tip portion 1 is the first tooth forming circle C 1 constituting the meshing portion 2. It does not protrude more radially outward. As a result, it is possible to suppress the tip position of the tooth tip portion 1 from protruding outward in the radial direction, and to prevent the tooth height from becoming long.

  And, the small tooth forming circle Cs constituting the tooth tip portion 1 is included so that the meshing portion 2 is formed, but the first tooth forming circle C1 is arranged is small in the tooth tip portion 1. Looking at how the tooth tip centerline, which is the short axis of the tooth forming circle Cs, penetrates, the first tooth forming circle C1 of the meshing portion 2 is first penetrated from the radially outer side, and then the tooth forming shape of the tooth tip portion 1 is small. It passes through the circle Cs, and then passes through the small tooth forming circle Cs of the tooth tip 1 and finally passes through the first tooth forming circle C1.

  That is, the portion of the circumference of the small tooth forming circle Cs that gradually forms the tooth tip 1 gradually approaches the curve of the first tooth forming circle C1 that includes the inside of the small tooth forming circle Cs. When the small tooth forming circle Cs of the portion 1 and the first tooth forming circle C1 of the meshing portion 2 are in contact with each other, the tooth tip portion 1 is connected to the meshing portion 2, and the first tooth forming shape of the meshing portion 2 is established. The portion where the meshing portion 2 is formed by the circle C1 and the small tooth forming circle Cs of the tooth tip portion 1 gradually move away from each other.

  The first tooth forming circle C1 in the meshing portion 2 gradually approaches the small tooth forming circle Cs of the tooth tip portion 1, and after passing through the connecting portion, the small tooth forming circle Cs of the tooth tip portion 1 gradually becomes the meshing portion. By moving away from the second first tooth forming circle C 1, the curve of the tooth tip portion 1 is connected to the curve of the meshing portion 2. The radius of curvature of the joint is not reduced, and it is smoothly connected, so the meshing with the outer rotor becomes smooth, the durability is improved, the noise when the rotor meshes is also reduced, and the quietness is reduced Get better.

  Since the first tooth forming circle C1 constituting the meshing part 2 is an ellipse larger than the small tooth forming circle Cs constituting the tooth tip part 1, the radius of curvature of the meshing part 2 can be increased, and the meshing part Since the second tooth can be raised and the thickness of the tooth can be reduced, the pitch angle of the tooth can be reduced.

  When the small tooth forming circle Cs constituting the tooth tip portion 1, the first tooth forming circle C1 constituting the meshing portion 2, and the second tooth forming circle C2 constituting the tooth bottom portion 3 are smoothly connected, the tooth shape of the inner rotor is obtained. A half-tooth region A1 is formed. And the tooth profile A for one tooth of the inner rotor can be created by arranging the half-tooth region A1 in line symmetry with respect to the diameter direction line Lc.

  Next, a second embodiment of the present invention will be described with reference to FIG. In the second embodiment, the half-tooth region A1 is composed of four tooth-forming circles C that are all elliptical. First, in the second embodiment, the four oval tooth forming circles C are, for convenience, the first tooth forming circle C1, the second tooth forming circle C2, the small first tooth forming circle Cs1, and the small second tooth forming circle. Let Cs2.

  And in the tooth tip part 1 of half-tooth area | region A1, a part of 1st tooth formation circle Cs1 with a small ellipse is used. In the meshing portion 2, a part of each of the oval first tooth forming circle C1 and the second tooth forming circle C2 is used continuously. Further, the tooth bottom portion 3 is a small second tooth forming circle Cs2 having an elliptical shape.

  The configuration of the tooth tip portion 1 is included in such a manner that a small first tooth forming circle Cs1 is partly in contact with the first tooth forming circle C1 constituting the meshing portion 2 as in the first embodiment. The small first tooth forming circle Cs1 constitutes the tooth tip portion 1, and the first tooth forming circle C1 constitutes a part of the meshing portion 2.

  Further, the remaining portion of the meshing portion 2 is constituted by an elliptical second tooth-forming circle C2, and the tooth bottom portion 3 is included in the second tooth-forming circle C2 while being partly in contact with each other. It is constituted by a second tooth forming circle Cs2 which is smaller than the two tooth forming circle. A small first tooth forming circle Cs1 constituting the tooth tip portion 1, a first tooth forming circle C1 constituting the meshing portion 2, a second tooth forming circle C2 and a small second tooth forming circle Cs2 constituting the tooth bottom portion 3. Are connected smoothly, a half-tooth region A1 of the tooth profile A of the inner rotor is formed. And the tooth profile A for one tooth of the inner rotor can be created by arranging the half-tooth region A1 in line symmetry with respect to the diameter direction line Lc.

  Next, another embodiment 1 will be described with reference to FIG. In another embodiment 1, the half-tooth region A1 is composed of four tooth-forming circles C that are all perfectly round. First, in the other embodiment 1, for the sake of convenience, the four perfectly circular tooth forming circles C are a perfect circular third tooth forming circle C3, a fourth tooth forming circle C4, a small third tooth forming circle Cs3, and a small first tooth forming circle Cs3. A four-tooth forming circle Cs4 is used.

  And in the tooth tip part 1 of the half-tooth region A1, a part of the third tooth forming circle Cs3 having a small perfect circle is used. In the meshing portion 2, a part of each of the round third tooth forming circle C3 and the fourth tooth forming circle C4 is used in a continuous manner. In addition, the tooth bottom portion 3 is a small fourth circle forming circle Cs4 having a perfect circular shape.

  The configuration of the tooth tip portion 1 is included in such a manner that a small third tooth formation circle Cs3 is partly in contact with the third tooth formation circle C3 constituting the meshing portion 2 as in the first embodiment. The small third tooth forming circle Cs3 constitutes the tooth tip portion 1, and the third tooth forming circle C3 constitutes a part of the meshing portion 2.

Further, the remaining portion of the meshing portion 2 is configured by a perfectly circular fourth tooth-forming circle C4, and the tooth bottom portion 3 is included in a small first shape that is partly in contact with the fourth tooth-forming circle C4. 4-tooth forming circle C
Consists of s4. A small third tooth forming circle Cs3 constituting the tooth tip 1, a third tooth forming circle C3, a fourth tooth forming circle C4 constituting the meshing portion 2, and a small fourth tooth forming circle constituting the tooth bottom 3. When Cs4 is smoothly connected, a half tooth region A1 of the tooth profile A of the inner rotor is formed. And the tooth profile A for one tooth of the inner rotor can be created by arranging the half-tooth region A1 in line symmetry with respect to the diameter direction line Lc.

  Next, another embodiment 2 will be described with reference to FIG. In another embodiment 2, the half-tooth region A1 is composed of a tooth-forming circle C having an elliptical shape and a true circular shape. Specifically, it consists of two oval first tooth forming circles C1, second tooth forming circles C2, two true circular small third tooth forming circles Cs3, and small fourth tooth forming circles Cs4.

  And in the tooth tip part 1 of the half-tooth region A1, a part of the third tooth forming circle Cs3 having a small perfect circle is used. In the meshing portion 2, a part of each of the oval first tooth forming circle C1 and the second tooth forming circle C2 is used continuously. In addition, the tooth bottom portion 3 is a small fourth circle forming circle Cs4 having a perfect circular shape.

Regarding the configuration of the tooth tip portion 1, the oval first tooth forming circle C 1 constituting the meshing portion 2 is included so that a small third round tooth forming circle Cs 3 is in contact with each other. A small third round tooth-forming circle Cs3 having a perfect circular shape constitutes the tooth tip portion 1, and an elliptical first tooth-forming circle C 1 constitutes a part of the meshing portion 2.

Further, the remaining portion of the meshing portion 2 is constituted by an elliptical second tooth-forming circle C2, and the tooth bottom portion 3 is a small fourth tooth shape that is included while partly contacting the tooth-forming circle C2. It is constituted by a forming circle Cs4. A third tooth forming circle Cs3 having a small round shape constituting the tooth tip portion 1, an elliptical first tooth forming circle C1 and a second tooth forming circle C2 constituting the meshing portion 2, and a tooth bottom portion 3 are constituted. When the small round fourth tooth forming circle Cs4 is smoothly connected, a half tooth region A1 of the tooth profile A of the inner rotor is formed. And the tooth profile A for one tooth of the inner rotor can be created by arranging the half-tooth region A1 in line symmetry with respect to the diameter direction line Lc.

A normal trochoidal curve rotor for comparison with the pump rotor of the present invention was designed. As an example of the invention according to the present invention, a pump rotor in which an inner rotor having 8 teeth and an outer rotor having 9 teeth are combined is shown in FIG. The invention product is a tooth profile created by the method of the first embodiment. FIG. 7 shows a comparative product, which employs a pump rotor having a trochoidal curve. The specifications of the tooth profile of the invention and comparative product are shown below.

A ... tooth profile, A1 ... half-tooth region, 1 ... tooth tip part, 2 ... meshing part, 3 ... tooth bottom part,
C ... tooth formation circle, Cs ... small tooth formation circle,
C1 ... first tooth formation circle, Cs1 ... small first tooth formation circle,
C2 ... second tooth forming circle, Cs2 ... small second tooth forming circle,
C3 ... third tooth formation circle, Cs3 ... small third tooth formation circle,
C4: Fourth tooth forming circle, Cs4: Small fourth tooth forming circle.

Claims (2)

In the tooth profile of the inner rotor of the internal gear pump, there are three tooth forming circles that are ellipses constituting the half tooth region of the tooth profile, and there are three tooth forming circles, two of which are the tooth forming circles. , One of the small tooth-forming circles is used as a combination including the whole of the small tooth-forming circle while inscribed in the other large tooth-forming circle, and the tip of the small tooth-forming circle is part of the small tooth-forming circle. A portion of the larger tooth forming circle in which the small tooth forming circle is inscribed and contained, and a part of the other tooth forming circle circumscribing the large tooth forming circle is formed. tooth bottom portion is formed by the larger tooth shaped circle, with a size enclosing the tooth profile of the tooth tip which is formed by the small tooth forming circles, the small tooth forming circles, the larger tooth formation Pump rotor, wherein a portion inwardly of the circle formed by inclusion in tooth shaped circle entire small tooth shaped yen is large so as to contact. The tooth profile of the inner rotor of the internal gear pump is a tooth forming circle that is an ellipse that constitutes the half tooth region of the tooth profile, and includes four tooth forming circles, two of which are the tooth forming circles. , One set being a small tooth forming circle and inscribed in the other large tooth forming circle and including the whole of the small tooth forming circle, there are two sets. addendum portion is formed in some tooth profile forming a circle, the tooth bottom portion is formed at a portion of the small tooth shaped circle second set, a part between the other two of said larger tooth shaped circle circumscribing the engagement portion of the semi-tooth region is formed with the large tooth shaped circle, with a size enclosing the tooth profile of the tooth tip which is formed by the small tooth forming circles, the small tooth shaped circles The large tooth formation Pump rotor, wherein a portion inwardly of the circle formed by inclusion in tooth shaped circle entire small tooth shaped yen is large so as to contact.

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