JP2020153351A - Internal gear pump - Google Patents

Abstract

To provide an internal gear pump which can supply oil to an area between a shaft support part and a protruding part efficiently and achieve low costs.SOLUTION: An internal gear pump according to one embodiment of the invention includes: an outer rotor 41; an inner rotor 42; a pump shaft 13; and a case 11 having a support hole 23 through which the pump shaft 13 penetrates. The support hole 23 includes: a shaft support part 25 into which a spigot part 52 is inserted and which rotatably supports the inner rotor 42 through the spigot part 52; and a seal support part 26 which continues to the outer side of the case 11 relative to the shaft support part 25 and into which an oil seal 14 for sealing a gap between itself and the pump shaft 13 is fitted. In the support hole 23, a portion defined between the spigot part 52 and the oil seal 14 is formed with a buffer chamber 100 capable of storing oil. An inner peripheral surface of the support hole 23 is formed with a communication groove 101 connecting the buffer chamber 100 with the shaft support part 25.SELECTED DRAWING: Figure 4

Description

The present invention relates to an inscribed gear pump.

In the inscribed gear pump, the inner rotor having the outer teeth rolls (eccentric rotation) with respect to the outer rotor inside the outer rotor having the inner teeth. As a result, the volume of the pump chamber formed between the internal teeth and the external teeth changes, and the liquid is discharged.

In this type of inscribed gear pump, the inner rotor includes an in-row portion that protrudes in the axial direction with respect to the rotor body in which the outer teeth are formed (see, for example, Patent Document 1 below). The inner rotor is rotatably supported by the case by slidably supporting the in-row portion in the bearing hole formed in the case. Further, in Patent Document 1 below, an annular oil groove is formed on the outer peripheral surface of the in-row portion. According to this configuration, the oil leaked to the fitting portion between the in-row portion and the bearing hole is collected in the oil groove, and it is said that wear between the inner peripheral surface of the bearing hole and the outer peripheral surface of the in-row portion can be prevented. ..

Japanese Unexamined Patent Publication No. 2004-353479

However, in the above-mentioned conventional technique, there is room for improvement in efficiently supplying oil between the inner peripheral surface of the bearing hole and the outer peripheral surface of the inlay portion. Further, there is also a problem that the processing cost is high in order to form the annular oil groove as in the above-mentioned conventional technique.

The present invention provides a low-cost inscribed gear pump capable of efficiently supplying oil between a shaft support portion and a protruding portion.

In order to solve the above problems, the present invention has adopted the following aspects.
The inscribed gear pump according to one aspect of the present invention includes a tubular outer rotor having internal teeth and
The rotor body has an outer tooth forming a pump chamber between the inner tooth and the rotor body, and a protrusion protruding axially from the rotor body, and the outer rotor is eccentric to the outer rotor inside the outer rotor. It has an inner rotor that is rotatably configured together with the outer rotor, a rotating shaft that is fixed to the inner rotor and rotates around the axis of the inner rotor, and a through hole through which the rotating shaft penetrates, and accommodates the outer rotor and the inner rotor. The through hole is provided with a shaft support portion through which the projecting portion is inserted and rotatably supporting the inner rotor via the projecting portion, and a shaft support portion of the case with respect to the shaft support portion. A seal support portion that is connected to the outside and is fitted with an oil seal that seals between the rotating shaft and the rotating shaft is provided, and a space defined between the protruding portion and the oil seal in the through hole. Is formed with a buffer chamber capable of accommodating oil, and a communication groove connecting the buffer chamber and the shaft support portion is formed on the inner peripheral surface of the through hole.

In the inscribed gear pump, for example, a part of the oil contained in the pump chamber leaks through between the case and each rotor. The oil leaking from the pump chamber flows axially through between the protrusion and the shaft support and enters the buffer chamber. The oil that has entered the buffer chamber is blocked by the oil seal, which prevents leakage to the outside of the case.
Here, in this embodiment, the oil in the buffer chamber is interposed between the inner peripheral surface of the shaft support portion and the outer peripheral surface of the protruding portion through the communication groove. As a result, it is possible to lubricate between the inner peripheral surface of the shaft support portion and the outer peripheral surface of the protruding portion, and to suppress wear between the inner peripheral surface of the shaft support portion and the outer peripheral surface of the protruding portion. As a result, durability can be improved.
Moreover, in this embodiment, the oil leaked into the buffer chamber is used. Therefore, as compared with the case where oil is supplied from the discharge chamber, for example, the pressure of the oil required to supply the oil between the inner peripheral surface of the shaft support portion and the outer peripheral surface of the protruding portion while suppressing the decrease in the discharge pressure. Can be secured.
Further, since the communication groove is configured to open in the buffer chamber, for example, the communication groove can be formed together when the case is molded by the mold. As a result, the cost can be reduced as compared with the configuration in which the communication groove is separately formed by cutting or the like after molding the case.

In the inscribed gear pump of this embodiment, a suction chamber and a discharge chamber that can communicate with the pump chamber as the outer rotor and the inner rotor rotate are formed in a portion located around the through hole inside the case. The communication groove may be formed in the same phase as the suction chamber in the circumferential direction around the axis.
In this embodiment, the pump chamber is configured to be able to communicate with the suction chamber and the discharge chamber by the rotation of the outer rotor and the inner rotor. In this case, the inner rotor may rotate in a state of being pressed against the portion of the inner peripheral surface of the shaft support portion facing the suction chamber due to the discharge pressure.
Therefore, in this embodiment, since the communication groove is formed in the same phase as the suction chamber, oil can be efficiently supplied to the portion of the inner peripheral surface of the shaft support portion facing the suction chamber. As a result, wear between the shaft support portion and the outer peripheral surface of the protruding portion can be more reliably suppressed.

In the inscribed gear pump of this embodiment, the inner diameter of the seal support portion is formed to be larger than that of the shaft support portion, and the seal support portion and the shaft support portion are connected via a stepped surface to form the buffer. The chamber may be defined between the oil seal and the stepped surface inside the seal support portion.
In this embodiment, it becomes easier to secure the volume of the buffer chamber as compared with the case where the inner diameter of the seal support portion is formed to be equal to or smaller than that of the shaft support portion. Therefore, it becomes easier to supply oil between the inner peripheral surface of the shaft support portion and the outer peripheral surface of the inlay portion.

According to each of the above aspects, it is possible to provide a low-cost inscribed gear pump capable of efficiently supplying oil between the shaft support portion and the protruding portion.

It is an exploded perspective view of the inscribed gear pump which concerns on embodiment. It is sectional drawing corresponding to line II-II of FIG. FIG. 3 is a view taken along the line III of FIG. It is operation explanatory drawing of an inscribed gear pump.

Next, an embodiment of the present invention will be described with reference to the drawings. In each of the following embodiments, the corresponding configurations may be designated by the same reference numerals and description thereof may be omitted.
[Inscribed gear pump]
FIG. 1 is an exploded perspective view of the inscribed gear pump 1. FIG. 2 is a cross-sectional view corresponding to line II-II of FIG.
As shown in FIGS. 1 and 2, the inscribed gear pump 1 of the present embodiment is mounted on, for example, a vehicle. The inscribed gear pump 1 is attached to the cylinder block 2 (see FIG. 2), for example, in the engine room. The inscribed gear pump 1 pumps up the oil contained in the oil pan (not shown) according to the rotation of the engine (crankshaft 3), and then sends it to the lubricating member, cooling member, hydraulic device, etc. to which the oil is supplied. To do. The inscribed gear pump 1 may be mounted on a vehicle other than the vehicle. In the following description, the extending direction of the crankshaft 3 will be described as the X direction.

The inscribed gear pump 1 includes a case 11, a pump unit 12, a pump shaft (rotary shaft) 13, and an oil seal 14.
<Case>
The case 11 is formed in a box shape that opens toward the first side in the X direction (the side facing the cylinder block 2). The peripheral wall portion 20 of the case 11 is attached to the side wall 2a of the cylinder block 2 with the opening of the case 11 facing the cylinder block 2. As a result, the pump accommodating portion S is defined between the case 11 and the cylinder block 2. The pump accommodating portion S has a tubular space because the inner peripheral surface of the peripheral wall portion 20 is formed in a circular shape centered on the axis O1 when viewed from the X direction.

A support hole 23 is formed at a position eccentric with respect to the axis O1 at the end portion 21 of the case 11. The support hole 23 is formed in a circular shape centered on the axis O2 parallel to the axis O1 when viewed from the X direction. The support hole 23 is open toward the outside (for example, an oil pan) of the inscribed gear pump 1.

In the present embodiment, the support hole (through hole) 23 has a stepped shape in which the inner diameter is enlarged as it is located on the second side (the side away from the cylinder block 2) in the X direction. Specifically, the support hole 23 includes a shaft support portion 25 and a seal support portion 26.

The shaft support portion 25 is a portion of the support hole 23 located on the first side in the X direction.
The seal support portion 26 is a portion of the support hole 23 located on the second side in the X direction. The seal support portion 26 is formed to have a larger diameter than the shaft support portion 25. The seal support portion 26 is connected to the shaft support portion 25 via a stepped surface 27. In the present embodiment, the stepped surface 27 projects from the second side edge in the X direction of the shaft support portion 25 in the direction orthogonal to the axis O2 (hereinafter, referred to as the second radial direction).

In the end portion 21, a suction chamber 31 and a discharge chamber 32 recessed on the second side in the X direction are formed in a portion located around the support hole 23. The suction chamber 31 and the discharge chamber 32 are formed in an arc shape along the direction around the axis O1 (hereinafter referred to as the first circumferential direction), and are arranged at intervals in the first circumferential direction. The portion of the end portion 21 located between the suction chamber 31 and the discharge chamber 32 has a partition wall (first partition wall 33 and second partition wall 34) that partitions the suction chamber 31 and the discharge chamber 32 in the first circumferential direction. It is configured. The shape and the like of the suction chamber 31 and the discharge chamber 32 can be appropriately changed as long as at least a part of the suction chamber 31 and the discharge chamber 32 can communicate with each other in the pump chamber 59 described later.

A suction port 35 for communicating the inside and outside of the suction chamber 31 is formed in a portion of the peripheral wall portion 20 facing the suction chamber 31. The suction chamber 31 communicates with an oil pan (not shown) or the like through a suction port 35. That is, the suction chamber 31 connects the oil pan and the pump accommodating portion S.
A discharge port 36 for communicating the inside and outside of the discharge chamber 32 is formed in a portion of the peripheral wall portion 20 facing the discharge chamber 32. The discharge chamber 32 is connected to the above-mentioned oil supply target or the like through the discharge port 36. That is, the discharge chamber 32 connects the pump accommodating portion S and the oil supply target.

<Pump section>
FIG. 3 is a view taken along the line III of FIG. In FIG. 3, the oil seal 14 and the like are not shown in order to make the pump unit 12 easy to understand.
As shown in FIGS. 1 to 3, the pump unit 12 includes an outer rotor 41 and an inner rotor 42.
The outer rotor 41 is formed in a tubular shape arranged coaxially with the axis O1. The outer rotor 41 includes an outer cylinder portion 45 and internal teeth 46.
The outer cylinder portion 45 is housed in the pump accommodating portion S. The outer cylinder portion 45 is configured to be slidable on the inner peripheral surface of the peripheral wall portion 20. That is, the outer rotor 41 is supported on the inner peripheral surface of the peripheral wall portion 20 so as to be rotatable around the axis O1.
The internal teeth 46 are formed on the inner peripheral surface of the outer cylinder portion 45. The internal teeth 46 are formed, for example, along a trochoidal curve or by an envelope such as a trochoidal curve.

The inner rotor 42 is formed in a tubular shape arranged coaxially with the axis O2. Specifically, the inner rotor 42 includes a rotor main body 51 and an in-row portion 52.
The rotor main body 51 includes an inner cylinder portion 55 and external teeth 56.

The inner cylinder portion 55 is arranged inside the outer rotor 41 in the pump accommodating portion S.
The outer teeth 56 are formed on the outer peripheral surface of the inner cylinder portion 55. The external teeth 56 are formed, for example, along a trochoidal curve or in a combination of ellipses. The number of outer teeth 56 is one less than the number of internal teeth 46.

The in-row portion 52 projects from the inner peripheral edge of the inner cylinder portion 55 to the second side in the X direction. The in-row portion 52 is formed in a tubular shape arranged coaxially with the inner cylinder portion 55. The inlay portion 52 is inserted into the support hole 23. The in-row portion 52 is configured to be slidable on the inner peripheral surface of the shaft support portion 25 described above. That is, the inner rotor 42 is supported on the inner peripheral surface of the shaft support portion 25 so as to be rotatable around the axis O2.

In the pump unit 12 of the present embodiment, a pump chamber 59 is defined between the internal teeth 46 and the external teeth 56. The pump chamber 59 is partitioned in the first circumferential direction when the internal teeth 46 and the external teeth 56 are in close proximity to or in contact with each other. The volume of each pump chamber 59 changes depending on the amount of engagement between the internal teeth 46 and the external teeth 56. That is, the volume of each pump chamber 59 is small in the portion where the amount of engagement between the internal teeth 46 and the external teeth 56 is large, and is large in the portion where the amount of engagement between the internal teeth 46 and the external teeth 56 is small. In the inscribed gear pump 1, the rotation of the outer rotor 41 and the inner rotor 42 causes the volume of each pump chamber 59 to repeatedly expand and contract to deliver oil.

When each pump chamber 59 is arranged at a portion that overlaps the suction chamber 31 described above when viewed from the X direction, the pump chamber 59 communicates with the suction chamber 31 in the X direction. On the other hand, when each pump chamber 59 is arranged at a portion overlapping the discharge chamber 32 described above when viewed from the X direction, the pump chamber 59 communicates with the discharge chamber 32 in the X direction.

In the present embodiment, the inner rotor 42 is formed with a fitting hole 60 that penetrates the inner cylinder portion 55 and the inner row portion 52 in the X direction. As shown in FIG. 3, the fitting hole 60 is formed in a flat shape (non-round shape) when viewed from the X direction. Specifically, the inner peripheral surface of the fitting hole 60 has a pair of hole-side arc portions 61 and a pair of hole-side detent portions 62 in the circumferential direction around the axis O2 (hereinafter referred to as the second circumferential direction). It is formed in a row alternately.
The hole-side arc portion 61 is formed in an arc shape centered on the axis O2. The hole-side arc portions 61 face each other with the axis O2 interposed therebetween.

The hole-side detent portion 62 is connected to each hole-side arc portion 61 in the second circumferential direction. That is, the hole-side detent portion 62 bridges the end portions of the hole-side arc portions 61 facing each other in the second circumferential direction. The radius of curvature of the hole-side detent portion 62 is different from that of the hole-side arc portion 61. In the present embodiment, the hole-side detent portion 62 is formed on a flat surface (radius of curvature is infinite) extending along the tangential direction of the virtual circle L centered on the axis O2. That is, the center of curvature of the hole-side detent portion 62 is arranged at a position different from the axis O2.

In the present embodiment, the central angle θ1 of the hole-side arc portion 61 centered on the axis O2 is larger than the central angle θ2 of the hole-side detent portion 62. The axis O2 is located at the intersection of the straight line connecting the centers of the hole-side arc portions 61 in the second circumferential direction and the straight line connecting the centers of the hole-side detent portions 62 in the second circumferential direction. There is.

An oil flow groove 65 is formed in the central portion of the hole-side detent portion 62 in the second circumferential direction. The oil flow groove 65 is formed in an arc shape that is convex toward the outside in the second radial direction when viewed from the front in the X direction. The oil flow groove 65 is formed in the hole-side detent portion 62 over the entire length in the X direction. The front view shape of the oil flow groove 65, the position in the second circumferential direction, and the like can be changed as appropriate. Further, the configuration may not have the oil flow groove 65.

As shown in FIG. 2, the pump shaft 13 includes a shaft main body 71, a fitting portion 72, and an outward protruding portion 73. The shaft body 71, the fitting portion 72, and the outer protruding portion 73 may be integrally formed or may be formed separately.

The shaft body 71 is integrally connected to the second end of the crankshaft 3 in the X direction. The shaft body 71 extends in the X direction on the axis O2. That is, the shaft body 71 rotates around the axis O2 integrally with the crankshaft 3 as the crankshaft 3 rotates. The shaft body 71 may be indirectly connected to the crankshaft 3.

As shown in FIG. 3, the fitting portion 72 projects outward from the shaft body 71 in the second radial direction. The fitting portion 72 is formed in a flat shape (non-round shape) in front view by partially flattening the fitting portion 72 in the second circumferential direction.

The fitting portion 72 is fitted in the fitting hole 60 described above. Specifically, the outer peripheral surface of the fitting portion 72 is formed with a pair of shaft-side arc portions 81 and a pair of shaft-side detent portions 82 alternately connected in the second circumferential direction.
The shaft-side arc portion 81 is formed in an arc shape centered on the axis O2. The shaft-side arc portion 81 is formed following the hole-side arc portion 61 described above. The shaft-side arc portion 81 faces each other in the second radial direction with the axis O2 interposed therebetween.

The shaft-side detent portion 82 is connected to each shaft-side arc portion 81 in the second circumferential direction. That is, the shaft-side detent portion 82 bridges the end portions of the shaft-side arc portions 81 facing each other in the second circumferential direction. The radius of curvature of the shaft-side detent portion 82 is different from that of the shaft-side arc portion 81. In the present embodiment, the shaft-side detent portion 82 is formed on a flat surface parallel to the hole-side detent portion 62.

The fitting portion 72 is fitted in the fitting hole 60 in a state where the arc portions 61, 81 and the detent portions 62, 82 are aligned in the second circumferential direction. As a result, the inner rotor 42 rotates around the axis O2 as the pump shaft 13 rotates.

In the present embodiment, the outer protruding portion 73 is connected to the second side in the X direction with respect to the fitting portion 72. The outer protrusion 73 is formed in a columnar shape arranged coaxially with the axis O2. The outer protruding portion 73 passes through the seal support portion 26 and projects to the outside of the case 11. That is, the pump shaft 13 of the present embodiment penetrates the inner rotor 42 and the support hole 23 and projects to the outside of the case 11.

The oil seal 14 is interposed between the inner peripheral surface of the seal support portion 26 and the outer peripheral surface of the outer protruding portion 73. The oil seal 14 is formed in a ring shape centered on the axis O2, for example, by an elastically deformable material. The oil seal 14 is fitted between the inner peripheral surface of the seal support portion 26 and the outer peripheral surface of the outer protrusion 73 by fitting the outer protrusion 73 inside and inside the seal support 26. Is sealed. The portion of the outer protruding portion 73 that protrudes to the outside of the case 11 is connected to a drive shaft or the like.

In the present embodiment, the length of the oil seal 14 in the X direction is shorter than the length of the seal support portion 26. The oil seal 14 is held in the seal support portion 26 in a state of being separated from the stepped surface 27 in the X direction. Therefore, in the support hole 23, the space surrounded by the oil seal 14, the inlay portion 52, and the pump shaft 13 constitutes the buffer chamber 100. The buffer chamber 100 extends continuously in the second circumferential direction.

Here, on the inner peripheral surface of the shaft support portion 25 described above, a communication groove 101 is formed in the same phase as the suction chamber 31 (at the same position in the second circumferential direction). The communication groove 101 communicates the inside of the shaft support portion 25 (buffer chamber 100) with the inside of the seal support portion 26. Specifically, the communication groove 101 extends in the X direction. The second end of the communication groove 101 in the X direction opens into the buffer chamber 100 on the stepped surface 27. The first side end portion of the communication groove 101 in the X direction is terminated on the inner peripheral surface of the shaft support portion 25. A plurality of communication grooves 101 may be formed in the second circumferential direction. Further, the dimensions and the like of the communication groove 101 can be changed as appropriate. Further, the communication groove 101 may be configured to extend not only in the X direction but also in the second direction and the like.

<Action>
Next, the operation of the inscribed gear pump 1 described above will be described.
When the pump shaft 13 rotates around the axis O2 (eccentric rotation with respect to the axis O1) with the rotation of the crankshaft 3, the inner rotor 42 rotates around the axis O2 together with the pump shaft 13. Then, the rotational force of the inner rotor 42 is transmitted to the inner teeth 46 via the outer teeth 56, so that the outer rotor 41 rotates around the axis O1 while meshing with the inner rotor 42. That is, in the pump unit 12, the outer rotor 41 rotates around the axis O1 (arrow P2 in FIG. 3) and the inner rotor 42 rotates around the axis O2 (arrow P1 in FIG. 3), so that the inner rotor 42 becomes the outer rotor 41. Roll inside.

In the inscribed gear pump 1, the rolling of the inner rotor 42 causes the volume of each pump chamber 59 to repeatedly expand and contract to deliver oil. Specifically, when the inner rotor 42 passes over the suction chamber 31 while rolling, the volume of the pump chamber 59 is expanded, and the inside of the pump chamber 59 becomes negative pressure. Then, the oil that has flowed into the suction chamber 31 through the suction port 35 flows into the pump chamber 59. On the other hand, as the rolling of the inner rotor 42 passes over the discharge chamber 32 while rolling, the volume of the pump chamber 59 is reduced and the inside of the pump chamber 59 is pressurized. As a result, the oil in the pump chamber 59 is sent out into the discharge chamber 32. The oil delivered into the discharge chamber 32 is supplied to each supply target through the discharge port 36, and is used for lubrication and cooling of the supply target.

By the way, as described above, the pump chamber 59 is configured to be able to communicate with the suction chamber 31 and the discharge chamber 32 by the rotation of the outer rotor 41 and the inner rotor 42. In this case, the inner rotor 42 may rotate in a state of being pressed against the portion of the inner peripheral surface of the shaft support portion 25 facing the suction chamber 31 due to the pressure (discharge pressure) in the discharge chamber 32.

FIG. 4 is an operation explanatory view of the inscribed gear pump 1.
Here, as shown in FIG. 4, in the inscribed gear pump 1, for example, a part of the oil contained in the pump chamber 59 is between the cylinder block 2 and the pump section 12, or between the case 11 and the pump section 12. It leaks in between. For example, the oil leaked between the cylinder block 2 and the pump portion 12 (see arrow A) enters between the fitting portion 72 and the inner rotor 42 (fitting hole 60) from the first side in the X direction. After that, the oil that has entered between the fitting portion 72 and the inner rotor 42 flows toward the second side in the X direction and enters the buffer chamber 100. The oil that has entered the buffer chamber 100 is blocked by the oil seal 14, so that leakage to the outside of the case 11 is suppressed. The pressure in the buffer chamber 100 (buffer pressure) is lower than the pressure in the discharge chamber 32 (discharge pressure) and higher than the pressure in the suction chamber 31 (suction pressure).

Further, for example, the oil leaked between the case 11 and the pump portion 12 (see arrow B) passes between the end portion 21 and the inner cylinder portion 55 and reaches the outer peripheral surface of the in-row portion 52. The oil that has reached the outer peripheral surface of the in-row portion 52 penetrates into the buffer chamber 100 through between the outer peripheral surface of the in-row portion 52 and the inner peripheral surface of the shaft support portion 25.

The oil that has entered the buffer chamber 100 penetrates into the communication groove 101 due to the buffer pressure (see arrow C). The oil that has flowed into the communication groove 101 spreads on the inner peripheral surface of the shaft support portion 25, and is interposed between the inner peripheral surface of the shaft support portion 25 and the outer peripheral surface of the inlay portion 52. As a result, the space between the inner peripheral surface of the shaft support portion 25 and the outer peripheral surface of the inlay portion 52 can be lubricated with oil.

As described above, in the present embodiment, the communication groove 101 connecting the inside of the buffer chamber 100 and the inside of the shaft support portion 25 is formed on the inner peripheral surface of the support hole 23.
According to this configuration, the oil in the buffer chamber 100 is interposed between the inner peripheral surface of the shaft support portion 25 and the outer peripheral surface of the inlay portion 52 through the communication groove 101. As a result, it is possible to lubricate between the inner peripheral surface of the shaft support portion 25 and the outer peripheral surface of the inlay portion 52, and suppress wear between the inner peripheral surface of the shaft support portion 25 and the outer peripheral surface of the inlay portion 52. As a result, durability can be improved.
Moreover, in the present embodiment, the oil leaked into the buffer chamber 100 is used. Therefore, as compared with the case where oil is supplied from the discharge chamber 32, for example, it is necessary to suppress the decrease in the discharge pressure and to supply the oil between the inner peripheral surface of the shaft support portion 25 and the outer peripheral surface of the inlay portion 52. Oil pressure can be secured.
Further, since the communication groove 101 is configured to open into the buffer chamber 100, the communication groove 101 can also be formed, for example, when the case 11 is molded by the mold. As a result, the cost can be reduced as compared with the configuration in which the communication groove is separately formed by cutting or the like after molding the case 11.

In the present embodiment, the communication groove 101 is formed in the same phase as the suction chamber 31.
According to this configuration, oil can be efficiently supplied to the portion of the inner peripheral surface of the shaft support portion 25 and the outer peripheral surface of the inlay portion 52 facing the suction chamber 31 by the buffer pressure. Therefore, wear between the inner peripheral surface of the shaft support portion 25 and the outer peripheral surface of the inlay portion 52 can be more reliably suppressed.

In the present embodiment, the shaft support portion 25 and the seal support portion 26 are connected to each other via the stepped surface 27.
According to this configuration, it becomes easier to secure the volume of the buffer chamber 100 as compared with the case where the inner diameter of the seal support portion 26 is formed to be equal to or smaller than that of the shaft support portion 25. Therefore, it becomes easier to supply oil between the inner peripheral surface of the shaft support portion 25 and the outer peripheral surface of the inlay portion 52.

(Other variants)
Although preferable examples of the present invention have been described above, the present invention is not limited to these examples. The configuration can be added, omitted, replaced, and other changes can be made without departing from the spirit of the present invention. The present invention is not limited by the above description, but only by the appended claims.
For example, in the above-described embodiment, the configuration in which the communication groove 101 is formed in the same phase as the suction chamber 31 in the second circumferential direction has been described, but the configuration is not limited to this configuration. The communication groove 101 may be formed in the same phase as, for example, the discharge chamber 32.
In the above-described embodiment, the case where the shaft support portion 25 and the seal support portion 26 have different inner diameters has been described, but the present invention is not limited to this configuration. The shaft support portion 25 and the seal support portion 26 may have the same diameter as long as the buffer chamber 100 can be formed on the first side in the X direction of the oil seal 14.

In the above-described embodiment, the configuration in which the pair of arc portions and the pair of detent portions are alternately connected in the second circumferential direction has been described, but the present invention is not limited to this configuration. The arc portion and the detent portion may be one by one or a plurality of three or more.
In the above-described embodiment, the configuration in which the pump shaft 13 rotates integrally with the crankshaft 3 has been described, but the configuration is not limited to this configuration. That is, the inscribed gear pump may be configured to rotate independently of the rotation of the crankshaft 3.
In the above-described embodiment, the configuration in which the space of the pump chamber 59 is formed by the combination of the case 11 and the cylinder block 2 has been described, but the configuration is not limited to this configuration. That is, apart from the cylinder block 2, the case 11 may be closed by the pump cover to form a space for the pump chamber 59.
In addition, the case 11 may be formed with a drain hole for communicating the inside and outside of the buffer chamber 100. That is, a part of the oil leaked into the buffer chamber 100 may be discharged to an oil pan or the like through the drain hole. By adjusting the inner diameter and position of the drain hole, an appropriate lubrication effect can be exhibited.

In addition, it is possible to replace the constituent elements in the above-described embodiment with well-known constituent elements as appropriate without departing from the spirit of the present invention, and the above-mentioned modified examples may be appropriately combined.

1 ... Internal gear pump 11 ... Case 13 ... Pump shaft (rotary shaft)
14 ... Oil seal 23 ... Support hole (through hole)
25 ... Shaft support part 26 ... Seal support part 27 ... Step surface 31 ... Suction chamber 32 ... Discharge chamber 41 ... Outer rotor 42 ... Inner rotor 46 ... Internal teeth 51 ... Rotor body 52 ... Inlay part (protruding part)
56 ... External teeth 59 ... Pump chamber 100 ... Buffer chamber 101 ... Communication groove

Claims (3)

A tubular outer rotor with internal teeth and
The rotor body having external teeth forming a pump chamber between the internal teeth and the rotor body and a projecting portion extending axially from the rotor body, and eccentric to the outer rotor inside the outer rotor. An inner rotor that is rotatably configured with the outer rotor,
A rotating shaft that is fixed to the inner rotor and rotates around the axis of the inner rotor,
It has a through hole through which the rotating shaft penetrates, and includes a case for accommodating the outer rotor and the inner rotor.
The through hole is
A shaft support portion that rotatably supports the inner rotor through the protrusion while the protrusion is inserted.
A seal support portion that is connected to the outside of the case with respect to the shaft support portion and is fitted with an oil seal that seals between the shaft support portion and the rotating shaft is provided.
In the through hole, a buffer chamber capable of accommodating oil is formed in the space defined between the protrusion and the oil seal.
An inscribed gear pump in which a communication groove connecting the buffer chamber and the shaft support portion is formed on the inner peripheral surface of the through hole. Inside the case, a suction chamber and a discharge chamber that can communicate with the pump chamber are formed in a portion located around the through hole as the outer rotor and the inner rotor rotate.
The inscribed gear pump according to claim 1, wherein the communication groove is formed in the same phase as the suction chamber in the circumferential direction around the axis. The inner diameter of the seal support portion is formed to be larger than that of the shaft support portion, and the seal support portion and the shaft support portion are connected via a stepped surface.
The inscribed gear pump according to claim 1 or 2, wherein the buffer chamber is defined between the oil seal and the stepped surface inside the seal support portion.

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