JP3213356U - Internal gear pump - Google Patents

Abstract

An internal gear pump that prevents seizure between an end face of an external gear and a housing is provided. An external gear having a tooth portion formed on the outer peripheral surface and having a rotation shaft extending outwardly from the both end surfaces along the central axis at the center of both end surfaces; A housing 2 that accommodates an annular internal gear 30 having teeth on the inner peripheral surface, an external gear 20 and an internal gear 30 in a state in which the teeth are partially engaged with each other, and a housing 2. And a bearing that rotatably supports the rotating shaft 22 of the external gear 20. The external gear 20 is provided with through-holes 24 for bearing lubrication that are opened at both end faces thereof, and the openings are formed so as to at least partially overlap the bearing when viewed from the direction along the axis of the rotary shaft 22. The end face lubrication through-hole 25 is provided in the region sandwiched between the bottom circle of the tooth portion that is concentric and open to both end faces and the same diameter as the outer diameter of the bearing. [Selection] Figure 2

Description

  The present invention relates to an internal gear pump provided with an external gear and an internal gear in which a part of tooth portions mesh with each other.

  Conventionally, for example, the internal gear pump disclosed in Patent Document 1 below is known. The internal gear pump includes an integrally formed pinion gear (external gear) and a drive shaft, a ring gear (internal gear) externally fitted to the pinion gear, a front side mounting body and an end side mounting that accommodate the pinion gear and the ring gear. A body (housing), and a front bearing and a rear bearing which are provided on each of the front side mounting body and the end side mounting body and rotatably support the drive shaft.

  The pinion gear has teeth on the outer periphery, while the ring gear has an inner diameter that is larger than the outer diameter of the pinion gear and has teeth on the inner periphery. The pinion gear and the ring gear are partially engaged. The end-side attachment body is accommodated in the accommodation chamber, and the opening of the accommodation chamber is closed by the front-side attachment body. The pinion gear is provided with a small hole penetrating from one side surface to the other side surface at a boundary portion with the drive shaft.

  Thus, according to this internal gear pump, the pinion gear housed in the housing chamber is moved, for example, to the front bearing side by an external force, and the end surface of the pinion gear is pressed against the front mounting body. In addition, since hydraulic oil is supplied from the rear bearing side to the front bearing side through the small hole, seizure of the front bearing is prevented by this hydraulic oil. Conversely, even if the pinion gear moves to the rear bearing side and the end surface of the pinion gear is pressed against the end mounting body, hydraulic oil is supplied from the front bearing side to the rear bearing side through the small hole, and this operation The oil prevents seizure of the rear bearing.

  As described above, according to this conventional internal gear pump, the front bearing and the rear bearing are prevented from being seized by the action of the small hole.

Microfilm of Japanese Utility Model Application No. Sho 62-167076 (Japanese Utility Model Application Laid-Open No. 1-71185)

  By the way, in recent years, a pump capable of outputting higher-pressure hydraulic oil, that is, a high-pressure pump has been developed in response to a request in the field.

  However, when the hydraulic oil becomes higher in pressure, the contact surface pressure when the pinion gear moves in the axial direction thereof and comes into sliding contact with the front side mounting body or the end side mounting body increases, so the end surface of the pinion gear and the front side mounting There has been a problem that seizure occurs due to running out of oil between the body and the attachment body on the end side.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide an internal gear pump that prevents seizure between the end face of the external gear and the housing.

The present invention for solving the above problems
Toothed portions are formed on the outer peripheral surface, and external gears each having a rotation shaft extending outwardly from the both end surfaces along the central axis at the center portions of the both end surfaces;
An annular internal gear having teeth formed on the inner peripheral surface;
A housing that accommodates the external gear and the internal gear in a state in which a part of the tooth portion meshes with each other;
A bearing that rotatably supports both rotation shafts of the external gear within the housing;
The external gear includes a through-hole for bearing lubrication that is opened at both end faces thereof, and the opening is formed so as to at least partially overlap the bearing when viewed from the direction along the axis of the rotating shaft. In the internal gear pump,
Further, the external gear is open at both end faces thereof, and is used for end face lubrication drilled in a region sandwiched by a bottom circle of the tooth portion that is a concentric circle and a circle having the same diameter as the outer diameter of the bearing. The present invention relates to an internal gear pump having a through hole.

  In this internal gear pump, the external gear accommodated in the housing is moved to one side in the axial direction by an external force, for example, and the end surface on one side of the external gear is the internal gear on the same side of the housing. When slidably contacted with the end face, the high-pressure working liquid on the other side is supplied to the bearing disposed on the one side via the bearing lubrication through-hole, whereby seizure occurs on the bearing on the one side. Is prevented.

  Further, the high-pressure working liquid on the other side is also supplied between the end surface on one side of the external gear and the inner end surface on the same side of the housing via the through hole for end surface lubrication. Therefore, the gap between them is lubricated, and seizure is prevented from occurring in the same part.

  Conversely, when the external gear moves to the other side in the axial direction and the end surface on the other side of the external gear slides on the inner end surface on the other side of the housing, the high-pressure operation on the one side is performed. The liquid is supplied to the bearing disposed on the other side through the bearing lubrication through-hole, thereby preventing seizure from occurring on the other side bearing.

  Further, the high-pressure working liquid on the one side is also supplied between the end surface on the other side of the external gear and the inner end surface on the other side of the housing via the through hole for end face lubrication. Therefore, the gap between them is lubricated, and seizure is prevented from occurring in the same part.

  As described above, according to the internal gear pump according to the present invention, even if the external gear moves in the axial direction, the end surface of the external gear and the inner surface of the housing are connected via the through hole for end surface lubrication. The working liquid is supplied between the end faces and lubricated, and the pressure difference acting on each end face of the external gear, that is, the difference in the face pressure is reduced, thereby preventing seizure from occurring in the same part. . In addition, the working liquid is supplied to the bearing through a through hole for lubricating the bearing, thereby preventing the bearing from being seized.

  Further, the internal gear pump according to the present invention preferably includes a plurality of the bearing lubrication through holes and end face lubrication through holes formed at equal intervals.

  If it does in this way, rotation of an external gear can be stabilized and it can prevent that unstable behaviors, such as vibration, arise. Further, the working liquid can be supplied in a well-balanced manner between the end face of the external gear and the inner end face of the housing and to the bearing, and seizure in these parts can be effectively prevented.

In the present invention, the end face lubricating through-hole, the tooth root D ₁ the diameter of the _circle, when the outer diameter of the bearing and D _2, puncture on a circle diameter D _P is in the range of the following formula It is preferable to be provided.
0.9 (D ₁ + D ₂ ) / 2 ≦ D _P ≦ 1.1 × (D ₁ + D ₂ ) / 2

  If the arrangement position of the through hole for end face lubrication is within this range, lubrication between the end face of the external gear and the inner end face of the housing can be performed satisfactorily.

Further, in the present invention, it is preferable that the diameter d ₁ of the end surface through hole for lubrication is set within the range of the following formula.
0.3 (D ₁ -D ₂ ) / 2 ≦ d ₁

The diameter d ₁ of the end face lubrication holes By setting this range, is possible to supply a sufficient amount of hydraulic fluid lubrication between the end face and the inner end surface of the housing of the external gear to satisfactorily perform it can.

  According to the internal gear pump according to the present invention, even if the external gear moves in the axial direction, it is provided between the end face of the external gear and the inner end face of the housing via the through hole for end face lubrication. The working liquid is supplied and lubricated, and further, the pressure difference acting on each end face of the external gear, that is, the difference in surface pressure, is reduced, thereby preventing seizure from occurring in the same part. In addition, the working liquid is supplied to the bearing through a through hole for lubricating the bearing, thereby preventing the bearing from being seized.

It is a front sectional view of the internal gear pump according to one embodiment of the present invention, and is a sectional view in the direction of arrow BB in FIG. It is a sectional side view of the internal gear pump which concerns on this embodiment, and is sectional drawing of the arrow AA direction in FIG. It is the side view which showed the external gear which concerns on this embodiment, and is a side view of the arrow E direction in FIG. It is a front sectional view showing an external gear according to the present embodiment, and is a sectional view in the direction of arrow CC in FIG. It is explanatory drawing for demonstrating the effect of the internal gear pump which concerns on this embodiment. It is explanatory drawing for demonstrating the effect of the internal gear pump which concerns on this embodiment.

  Hereinafter, specific embodiments of the present invention will be described with reference to the drawings. As shown in FIGS. 1 and 2, the internal gear pump 1 of this example includes a housing 2 in which a storage chamber 4 is formed, and an external gear 20 and an internal gear 30 stored in the storage chamber 4. With. For the sake of explanation, the front-rear direction set for convenience is shown in FIG.

  The housing 2 opens to the front end surface (front end surface), and has a main body 3 in which the storage chamber 4 having a space with a circular cross-section is formed, and a liquid-tight shape on the front end surface of the main body 3. The cover body 10 is fixed, the rear cover body 9 is fixed to the rear end face (rear end face) of the main body 3, and the front cover body 14 is provided on the front side of the cover body 10.

  The external gear 20 includes a gear portion 21 having a tooth portion formed on the outer peripheral surface thereof, and a rotation shaft extending rearward from the both end surfaces 21a and 21b along the central axis at the center portion of the gear portion 21. 22 and a rotating shaft 23 extending forward. The internal gear 30 is an annular gear having a tooth portion formed on the inner peripheral surface, and the gear portion 21 of the external gear 20 is disposed inside the ring.

  The main body 3 is provided with a through hole 5 opened at the inner end surface 4 a of the storage chamber 4 and a rear end surface of the main body 3 at the center thereof, and the central axis of the storage chamber 4 is the center of the through hole 5. It is in an eccentric state from the central axis. Then, the internal gear 30 is rotatably fitted in the storage chamber 4, and the external gear is placed inside the ring of the internal gear 30 in a state where a part of the tooth portions are meshed with each other. As a result, the internal gear 30 and the gear portion 21 of the external gear 20 are stored in the storage chamber 4 in an eccentric state. A bearing 17 is fitted into the through-hole 5, and a rotating shaft 22 of the external gear 20 is rotatably supported in a state of being inserted into the bearing 17.

  On the inner end surface 4a of the storage chamber 4, a crescent-shaped partition piece 6 called a crescent protrudes from a portion where the gear portion 21 of the external gear 20 and the internal gear 30 are not meshed with each other. The inner peripheral surface of the tooth portion of the internal gear 30 is in sliding contact with the protrusion of the partition piece 6, and the outer peripheral surface of the tooth portion of the gear portion 21 is in sliding contact with the concave portion of the partition piece 6.

  On the other hand, the cover body 10 is provided with a through-hole 11 that opens at the front end face and the rear end face 10a at the center thereof. The front side of the through hole 11 is formed to have a larger diameter than the rear side, and a bearing 18 is inserted into a rear small diameter portion, and the rotary shaft 23 is inserted in the bearing 18 and is supported rotatably. ing. Further, the front portion of the rotary shaft 23 from the bearing 18 is rotatably supported by a bearing 15 inserted into the large diameter portion of the through hole 11, and the front portion of the bearing 15 is sealed by an oil seal 16. ing. The large-diameter portion of the through hole 11 is closed by the front lid 14, and the oil seal 16 is held by the front lid 14.

  The rotary shaft 23 is provided with a key 23a at the front end thereof, and the rotary shaft 23 and an output shaft of a drive motor are appropriately connected via the key 23a, and the rotary shaft 23 is connected by the drive motor. By rotating, the external gear 20 rotates in the direction of the arrow shown in FIG.

  The main body 3 is formed with an arcuate suction side recess 7 opened in the inner wall surface 4a on the upstream side in the rotation direction of the external gear 20 (hereinafter simply referred to as “upstream side”) with respect to the partition piece 6. In addition, an arc-shaped discharge-side recess 8 that is similarly open to the inner wall surface 4a is formed on the downstream side in the rotational direction (hereinafter simply referred to as “downstream side”) with respect to the partition piece 6.

  The suction-side recess 7 and the discharge-side recess 8 open along the root path in the gear portion 21 of the external gear 20 and the root path in the internal gear 30, respectively. The portion has a shape that gradually widens from the upstream side toward the downstream side, and the opening of the discharge-side concave portion 8 has a shape that gradually widens from the downstream side toward the upstream side.

  The cover body 10 is formed with a suction channel 12 and a discharge channel 13. One of the suction flow paths 12 opens on one side surface (the lower surface in FIG. 1) of the cover body 10, and the other opens on the rear end surface 10 a of the cover body 10. Further, one of the discharge flow paths 13 is opened on the other side surface (upper surface in FIG. 1) of the cover body 10, and the other is opened on the rear end face 10a. The openings to the rear end face 10a of the suction flow channel 12 and the discharge flow channel 13 are opposed to the suction side concave portion 7 and the discharge side concave portion 8 with the gear portion 21 and the internal gear 30 of the external gear 20 interposed therebetween. The opening to the rear end surface 10a of the suction flow channel 12 is gradually widened from the upstream side toward the downstream side, and the opening to the rear end surface 10a of the discharge flow channel 13 is It gradually becomes wider from the downstream side toward the upstream side.

  Further, as shown in FIGS. 3 and 4, the external gear 20 has two bearing lubrication through holes 24, 24 opened on both end faces 21 a, 21 b and two end face lubrications. Through-holes 25, 25 are provided. The through hole 24 for bearing lubrication is bored so that the opening thereof overlaps at least partly with the bearings 17 and 18 when viewed from the direction along the axis of the rotary shafts 22 and 23. Further, the end face lubricating through hole 25 is formed in a region sandwiched by a concentric circle at the bottom of the gear portion 21 and a circle having the same diameter as the outer diameter of the bearings 17 and 18. The bearing lubrication through holes 24 and 24 and the end surface lubrication through holes 25 and 25 are alternately drilled at equal angular intervals, and the end surface lubrication through holes 25 and 25 are connected to the tooth crest portion of the gear portion 21. They are provided at the same angular position.

  According to the internal gear pump 1 of the present example having the above-described configuration, first, an appropriate pipe (not shown) connected to an appropriate tank that stores hydraulic oil is formed on the lower surface of the cover body 10. Connected to the opening of the flow channel 12 and connected to an appropriate pipe connected to an appropriate hydraulic device to the opening of the discharge flow channel 13 formed on the upper surface of the cover body 10. After appropriately connecting a drive motor to the motor, the drive motor is operated to rotate the external gear 20.

  As a result, the rotational force is transmitted to the internal gear 30 in which the external gear 20 and a part of the tooth portion mesh with each other, and the gears 20 and 30 rotate in an eccentric state, and the suction flow path 12 is formed. That is, on the upstream side of the partition piece 6, the tooth portion of the external gear 20 and the tooth portion of the internal gear 30 are gradually separated from each other, and the space between the tooth portions is widened to produce a suction action. Then, this suction action acts on the suction flow path 12, and between the tooth portions of the gears 20, 30 through a pipe (not shown) connected to the tank and the suction flow path 12 connected thereto. Hydraulic fluid is inhaled.

  Then, the hydraulic oil sucked in this way is divided into an inner peripheral side and an outer peripheral side of the partition piece 6, and to the side where the discharge flow path 13 is formed, that is, downstream from the partition piece 6. Since the tooth portions of the gears 20 and 30 gradually approach and narrow between the tooth portions on the downstream side of the partition piece 6, the hydraulic oil transferred from the upstream side is pressurized and discharged. 13 and a pipe (not shown) connected to this and sent to the hydraulic equipment.

  In a normal case, the gear portion 21 of the external gear 20 is in an intermediate position in the storage chamber 4 in the axial direction, and the front end surface 21b of the gear portion 21 and the rear end surface 10a of the cover body 10 A gap is formed between the rear end surface 21a of the gear portion 21 and the inner end surface 4a of the storage chamber 4. Then, high pressure hydraulic oil flows into the gap between the front end surface 21b of the gear portion 21 and the rear end surface 10a of the cover body 10 from the discharge flow path 13 to lubricate the same portion. The bearing 18 is supplied to lubricate the bearing 18. In addition, high pressure hydraulic oil flows into the gap between the rear end surface 21a of the gear portion 21 and the inner end surface 4a of the storage chamber 4 from the discharge-side concave portion 8 to lubricate the same portion. The bearing 17 is supplied to lubricate the bearing 17.

  Thus, in the normal case, the above action causes the front end surface 21b of the gear portion 21 and the rear end surface 10a of the cover body 10 to be between the rear end surface 21a of the gear portion 21 and the inner end surface 4a of the storage chamber 4. The bearing 17 and the bearing 18 are each lubricated by the hydraulic oil, and seizure in each part is prevented.

  By the way, in the internal gear pump 1 of this example, a drive motor (not shown) is connected to the rotating shaft 23 of the external gear 20, and external force is input via this drive motor (not shown). As a result, the external gear 20 moves in the axial direction thereof, or the pressure difference of the hydraulic oil acting on the both end faces 21a and 21b of the gear portion 21 is locally increased, so that the pressure is increased from the higher pressure side. It is possible that a pressing force acts on the smaller side of the external gear 20 and the external gear 20 moves in the axial direction.

  In this case, in the internal gear pump 1 of this example, the external gear 20 moves to one side in the axial direction, for example, the cover body 10 side, and the front end surface 21b of the gear portion 21 is the cover body 10 side. When slidably contacting the rear end surface 10a, high-pressure hydraulic oil supplied from the discharge-side concave portion 8 between the rear end surface 21a of the gear portion 21 and the inner end surface 4a of the storage chamber 4 passes through the end surface lubricating through holes 25, 25. And is supplied between the front end surface 21 b of the gear portion 21 and the rear end surface 10 a of the cover body 10, and is supplied to the bearing 18 through the bearing lubrication through holes 24 and 24. Thereby, between the front-end surface 21b of the gear part 21, and the rear-end surface 10a of the cover body 10, and the bearing 18 are lubricated with hydraulic fluid, and the seizing in the part is prevented.

  On the contrary, when the external gear 20 moves to the inner end surface 4 a side of the storage chamber 4 and the rear end surface 21 a of the gear portion 21 slides on the inner end surface 4 a of the storage chamber 4, the gear from the discharge flow path 13 High-pressure hydraulic oil supplied between the front end surface 21 b of the portion 21 and the rear end surface 10 a of the cover body 10 passes through the end surface lubricating through holes 25, 25, so that the rear end surface 21 a of the gear portion 21 and the storage chamber 4 It is supplied between the inner end surface 4 a and the bearing 17 through the bearing lubrication through holes 24 and 24. Thereby, between the rear-end surface 21a of the gear part 21 and the inner end surface 4a of the storage chamber 4, and the bearing 17 are lubricated with hydraulic fluid, and the seizing in the part is prevented.

  Thus, according to the internal gear pump 1 of this example, even if the external gear 20 moves in the axial direction thereof, the rear end surface 21a of the gear portion 21 through the end surface lubricating through holes 25, 25. And the inner end surface 4a of the storage chamber 4 or between the front end surface 21b of the gear portion 21 and the rear end surface 10a of the cover body 10 are supplied with hydraulic oil and lubricated, respectively, and further, the front end surface 21b and the rear end surface The pressure difference acting on 21a, that is, the difference in surface pressure, is reduced, thereby preventing seizure from occurring in the same part. The bearings 17 and 18 are supplied with hydraulic fluid through the bearing lubrication through holes 24 and 24, thereby preventing the bearings 17 and 18 from being seized.

  Further, in the internal gear pump 1 of this example, the bearing lubrication through holes 24 and 24 and the end surface lubrication through holes 25 and 25 are alternately drilled at equal angular intervals. Can be made stable, and unstable behavior such as vibration can be prevented. Further, the hydraulic oil is balanced between the rear end surface 21a of the gear portion 21 and the inner end surface 4a of the storage chamber 4, between the front end surface 21b of the gear portion 21 and the rear end surface 10a of the cover body 10, and in the bearings 17 and 18. Can be supplied, and seizure in these parts can be effectively prevented.

  Incidentally, in the internal gear pump 1 of this example and the internal gear pump of the conventional structure in which the end face lubricating through holes 25 and 25 are omitted from the internal gear pump 1 of this example, the external gear 20 is connected to the cover body 10 side. The hydraulic oil pressure between the front end face 21b of the gear part 21 and the rear end face 10a of the cover body 10 (the front side pressure of the gear part), the rear end face 21a of the gear part 21 and the inside of the storage chamber 4 FIG. 5 and FIG. 6 show the results of measuring the pressure of the hydraulic oil between the end surface 4a (the rear pressure of the gear portion) and the pressure of the hydraulic oil in the discharge passage 13. 5 shows a case of an internal gear pump having a conventional structure, and FIG. 6 shows a case of the internal gear pump 1 of this example.

  As shown in FIG. 5, in the case of the internal gear pump having the conventional structure, when the external gear 20 moves to the cover body 10 side, the pressure on the front side of the gear portion 21 is reduced, while the rear side of the gear portion 21 is The pressure rises, creating a difference between the two. This indicates that it is difficult for hydraulic oil to flow between the front end surface 21b of the gear portion 21 and the rear end surface 10a of the cover body 10, and it can be seen that seizure is likely to occur between them.

  On the other hand, in the case of the internal gear pump 1 of this example, as shown in FIG. 6, even if the external gear 20 moves to the cover body 10 side, the pressure on the front side of the gear portion 21 and the rear side of the gear portion 21 It can be seen that a sufficient amount of hydraulic fluid flows between the front end surface 21b of the gear portion 21 and the rear end surface 10a of the cover body 10. Thereby, the seizing between the front end surface 21b of the gear part 21 and the rear end surface 10a of the cover body 10 is prevented.

  Further, in the internal gear pump 1 of the present example, the end surface lubrication through holes 25 and 25 are provided at the same angular position as the tooth crest portion of the gear portion 21, so that the outer surface of the gear portion 21 and the end surface lubrication through hole 25, The end face lubrication through holes 25 and 25 can be provided to minimize the reduction in the strength of the gear portion 21. it can.

Incidentally, the end face lubrication holes 25 and 25, the tooth root _{D 1} the diameter of a circle, as _{D 2} the outer diameter of the bearing 17, on a circle diameter _{D P} is in the range of the following formula preferably it is drilled _{(for D 1, D 2, D P} , see Figure 3).
0.9 (D ₁ + D ₂ ) / 2 ≦ D _P ≦ 1.1 × (D ₁ + D ₂ ) / 2
If the arrangement positions of the end surface lubricating through holes 25 and 25 are within this range, the front end surface 21b of the gear portion 21 and the rear end surface 10a of the cover body 10, and the rear end surface 21a of the gear portion 21 and the accommodating chamber are provided. The lubrication between the inner end surface 4a and the inner end surface 4a can be performed well.

Also, preferably the diameter d ₁ of the end face lubrication holes 25, 25 is set in a range represented by the following formula (for d _1, see FIG. 4).
0.3 (D ₁ -D ₂ ) / 2 ≦ d ₁
The diameter _{d 1} of the end face lubrication holes 25, 25 by setting in this range, between the rear end surface 10a of the front end face 21b and the cover member 10 of the gear portion 21, and a rear end surface 21a of the gear portion 21 accommodated It is possible to supply a sufficient amount of hydraulic fluid to satisfactorily lubricate between the inner end surface 4a of the chamber 4.

The diameter d ₂ of the bearing lubrication through holes 24, 24 is preferably is set within the range represented by the following formula (for d _2, see FIG. 4).
0.3 (D ₁ -D ₂ ) / 2 ≦ d ₂
The diameter d ₂ of the bearing lubrication through holes 24, 24 by setting this range, it is possible to supply a sufficient amount of hydraulic oil to satisfactorily perform the lubrication of the bearings 17, 18.

  As mentioned above, although one Embodiment of this invention was described, the specific aspect which this invention can take is not limited to this at all.

  For example, in the above example, the bearing lubrication through holes 24 and 24 and the end surface lubrication through holes 25 and 25 are round holes. However, the present invention is not limited to this, and various shapes of holes such as long holes and square holes may be used. Can be adopted. In addition, although the number of each provided is two, it is naturally not limited to this number, and may be more or less.

DESCRIPTION OF SYMBOLS 1 Internal gear pump 2 Housing 3 Main body 4 Storage chamber 6 Partition piece 7 Suction side recessed part 8 Discharge side recessed part 9 Rear cover body 10 Cover body 12 Suction flow path 13 Discharge flow path 14 Front cover body 15 Bearing 16 Oil seal 17 Bearing DESCRIPTION OF SYMBOLS 18 Bearing 20 External gear 21 Gear part 22, 23 Rotating shaft 24 Through hole for bearing lubrication 25 Through hole for end face lubrication 30 Internal gear

Claims (4)

Toothed portions are formed on the outer peripheral surface, and external gears each having a rotation shaft extending outwardly from the both end surfaces along the central axis at the center portions of the both end surfaces;
An annular internal gear having teeth formed on the inner peripheral surface;
A housing that accommodates the external gear and the internal gear in a state in which a part of the tooth portion meshes with each other;
A bearing that rotatably supports both rotation shafts of the external gear within the housing;
The external gear includes a through-hole for bearing lubrication that is opened at both end faces thereof, and the opening is formed so as to at least partially overlap the bearing when viewed from the direction along the axis of the rotating shaft. In the internal gear pump,
Further, the external gear is open at both end faces thereof, and is used for end face lubrication drilled in a region sandwiched by a bottom circle of the tooth portion that is a concentric circle and a circle having the same diameter as the outer diameter of the bearing. An internal gear pump comprising a through hole.   2. The internal gear pump according to claim 1, further comprising a plurality of through holes for bearing lubrication and through holes for end face lubrication that are formed at equiangular intervals. It said end face lubricating through-hole, D ₁ the diameter of the root _circle, when the outer diameter of the bearing and D _2, are bored on a circle diameter D _P is in the range of the following formula The internal gear pump according to claim 1, wherein the internal gear pump is provided.
0.9 (D ₁ + D ₂ ) / 2 ≦ D _P ≦ 1.1 × (D ₁ + D ₂ ) / 2 The end surface lubricating through-hole has a diameter d ₁ set within a range of the following formula, where D _{1 is} the diameter of the root circle and D ₂ is the outer diameter of the bearing. The internal gear pump of any one of thru | or 3.
0.3 (D ₁ -D ₂ ) / 2 ≦ d ₁

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