Gear pump device

Abstract

To provide a gear pump device which can improve efficiency as an example.SOLUTION: A gear pump device includes: a rotor unit having an inner gear and an outer gear; and a housing having a cylindrical inner peripheral surface surrounding the outer gear, a side surface away from the rotor unit in an axial direction and facing the rotor unit, a partitioning projection part which projects from the side surface and which partitions a rotor chamber into a low pressure region and a high pressure region, and a converging projection part that projects from the side surface toward the outer gear. The outer gear has a cylindrical outer peripheral surface that faces the inner peripheral surface with a gap therebetween and which is eccentric with respect to the inner peripheral face. The converging projection part includes a sealing surface facing the outer gear and a part with the smallest distance in the gap between the inner peripheral face and the outer peripheral face. A portion of the side surface that is adjacent to the converging projection part is further away from the rotor unit in the axial direction than the sealing surface and faces the gap.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] An embodiment of the present invention relates to a gear pump device. [Background technology]

[0002] A gear pump device including a rotor unit and a housing is known. The gear pump device rotates an inner gear and an outer gear of the rotor unit to transfer fluid between the meshing external teeth of the inner gear and the meshing internal teeth of the outer gear from a low-pressure region to a high-pressure region.

[0003] The housing accommodates the rotor unit. The inner circumferential surface of the housing and the outer circumferential surface of the outer gear face each other with a gap between them, and are eccentric to each other. As a result, the gap tapers toward the point where the distance between the inner circumferential surface and the outer circumferential surface is smallest (minimum distance part). When the rotor unit rotates, fluid is drawn into the minimum distance part, and the wedge effect increases the pressure of the fluid (oil film pressure) (Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2023-19757 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in conventional configurations, fluid can leak from the smallest gaps, which can reduce the oil film pressure in the smallest gaps. If this happens, the efficiency of the gear pump device can be reduced due to losses caused by sliding between the inner and outer circumferential surfaces.

[0006] Therefore, the present invention has been made in view of the above, and provides a gear pump device capable of improving efficiency. [Means for solving the problem]

[0007] As an example, a gear pump device according to an embodiment of the present invention includes a rotor unit having an inner gear rotatable about a rotation axis and an outer gear surrounding the inner gear, wherein a plurality of external teeth provided on the inner gear mesh with a plurality of internal teeth provided on the outer gear, a rotor chamber accommodating the rotor unit, a suction passage communicating with the rotor chamber, and a discharge passage communicating with the rotor chamber, and the gear pump device has a cylindrical inner circumferential surface facing the rotation axis and surrounding the outer gear, a side surface spaced apart from the rotor unit in the axial direction along the rotation axis and facing the rotor unit, and a cylindrical inner circumferential surface protruding from the side surface toward the rotor unit. The housing includes a partitioning protrusion that partitions the rotor chamber into a low-pressure region communicating with the suction passage and a high-pressure region communicating with the discharge passage, and a converging protrusion that protrudes from the side surface toward the outer gear. The outer gear has a cylindrical outer surface that faces the inner circumferential surface with a gap and is eccentric with respect to the inner circumferential surface. The converging protrusion has a sealing surface that faces the outer gear and a portion of the gap where the distance between the inner circumferential surface and the outer circumferential surface is smallest. A portion of the side surface adjacent to the converging protrusion around the rotation axis is spaced apart from the rotor unit in the axial direction relative to the sealing surface and faces the gap. Thus, for example, when the inner gear rotates in a rotational direction around the rotation axis, the outer gear also rotates approximately in the rotational direction due to meshing between the external teeth and the internal teeth. As the outer gear rotates, fluid in the rotor chamber also flows in the rotational direction, for example, through the gap. Because the inner and outer circumferential surfaces are eccentric to each other, the gap tapers toward the point where the distance between the inner and outer circumferential surfaces is smallest (the minimum portion). As a result, fluid flows into the minimum portion, increasing the fluid pressure (oil film pressure) through a wedge effect. The sealing surface of the converging convex portion covers the minimum portion in the vicinity, preventing fluid from leaking axially from the minimum portion. Therefore, the gear pump device can prevent a decrease in oil film pressure at the minimum portion due to fluid leakage, and ultimately prevent frictional loss from occurring between the inner and outer circumferential surfaces. Meanwhile, the side surface faces the outer gear and the gap, farther away from the sealing surface. Therefore, the gear pump device can prevent frictional loss and viscous shear loss from occurring between the side surface and the outer gear.As a result, the gear pump device can improve efficiency. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a cross-sectional view showing a gear pump device according to one embodiment. [Figure 2] FIG. 2 is a cross-sectional view schematically showing a part of the gear pump device of the embodiment taken along line F2-F2 in FIG. [Figure 3] FIG. 3 is a cross-sectional view schematically showing a part of the gear pump device of the embodiment taken along line F3-F3 in FIG. [Figure 4] FIG. 4 is a front view showing the ring seal of the embodiment. [Figure 5] FIG. 5 is a cross-sectional view that schematically shows a part of the outer gear, the casing, and the ring seal of the embodiment. [Figure 6] FIG. 6 is a front view showing a part of the ring seal of the embodiment. [Figure 7] FIG. 7 is a cross-sectional view schematically showing a part of the outer gear and the ring seal of the embodiment taken along line F7-F7 in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0009] An embodiment will be described below with reference to FIGS. 1 to 7. In this specification, components according to the embodiment and descriptions of the components may be described using multiple expressions. The components and their descriptions are merely examples and are not limited by the expressions in this specification. The components may also be identified by names different from those in this specification. Furthermore, the components may also be described using expressions different from those in this specification.

[0010] In the following description, "inhibit" is defined as, for example, preventing an event, action, or effect from occurring or reducing the magnitude of an event, action, or effect.

[0011] Fig. 1 is a cross-sectional view showing a gear pump device 10 of this embodiment. Fig. 2 is a cross-sectional view showing a part of the gear pump device 10 of this embodiment, taken along line F2-F2 in Fig. 1. As shown in Fig. 2, the gear pump device 10 of this embodiment is an internal gear pump (trochoid pump). The gear pump device 10 has a shaft 11, a rotor unit 12, a key 13, a housing 14, and a plurality of outer circumferential seals 15.

[0012] As shown in Fig. 1, the shaft 11 is formed in a generally cylindrical shape extending approximately along a first central axis Ax1. The first central axis Ax1 is an example of a rotation axis. The first central axis Ax1 is the central axis of the shaft 11. However, the first central axis Ax1 is not limited to this example.

[0013] The shaft 11 is mainly made of metal. However, the shaft 11 may be made of other materials. The shaft 11 is rotated in a first circumferential direction Dc1 about a first central axis Ax1 by a power source such as a motor. The first circumferential direction Dc1 is an example of a rotation direction.

[0014] For convenience, the terms axial direction, radial direction, and circumferential direction are defined herein. The axial direction is a direction along the first central axis Ax1. The radial direction is a direction perpendicular to the first central axis Ax1. The circumferential direction is a direction around the first central axis Ax1. The first circumferential direction Dc1 is included in the circumferential direction.

[0015] As shown in FIG. 2, the rotor unit 12 has an inner gear 21 and an outer gear 22. The inner gear 21 may also be referred to as an inner rotor. The outer gear 22 may also be referred to as an outer rotor. The inner gear 21 and the outer gear 22 are mainly made of a metal such as iron. However, the inner gear 21 and the outer gear 22 may also be made of other materials.

[0016] Fig. 3 is a cross-sectional view schematically showing a part of the gear pump device 10 of this embodiment taken along line F3-F3 in Fig. 2. As shown in Fig. 3, the inner gear 21 is formed in a substantially disk shape. The first central axis Ax1 is also, for example, the central axis of the inner gear 21. The inner gear 21 has two end faces 21a and an outer circumferential surface 21b.

[0017] The two end faces 21a are provided on both axial ends of the inner gear 21. The end faces 21a are formed to be substantially flat and face the axial direction. The outer peripheral surface 21b is a substantially cylindrical curved surface extending in the circumferential direction and faces radially outward.

[0018] As shown in FIG. 1 , the inner gear 21 is provided with an insertion hole 23 and a key groove 24. The insertion hole 23 extends along the first central axis Ax1 and passes through the inner gear 21 in the axial direction. The shaft 11 extends axially through the insertion hole 23. In other words, the shaft 11 passes through the insertion hole 23. The key groove 24 is recessed radially outward from the insertion hole 23.

[0019] 2, a plurality of external teeth 25 are provided on an outer peripheral surface 21b of the inner gear 21. The external teeth 25 protrude radially outward from the outer peripheral surface 21b and are arranged in the circumferential direction. The outer peripheral surface 21b forms the tooth bottoms of the external teeth 25.

[0020] The outer gear 22 is formed in a generally annular shape extending around a second central axis Ax2. That is, the second central axis Ax2 is the central axis of the outer gear 22. The second central axis Ax2 extends generally parallel to the first central axis Ax1 and is slightly spaced radially from the first central axis Ax1. Therefore, the axial direction is also the direction extending along the second central axis Ax2. The radial direction is roughly equal to the direction perpendicular to the second central axis Ax2. The circumferential direction is roughly equal to the direction around the second central axis Ax2.

[0021] The outer gear 22 surrounds the inner gear 21. In other words, the inner gear 21 is located inside the outer gear 22. As shown in Fig. 3, the outer gear 22 has two end faces 22a, an inner peripheral surface 22b, and an outer peripheral surface 22c.

[0022] The two end faces 22a are provided on both axial ends of the outer gear 22. The end faces 22a are formed substantially flat and face the axial direction. The end face 22a of the outer gear 22 is positioned on substantially the same plane as the end face 21a of the inner gear 21.

[0023] As shown in Fig. 2, the inner circumferential surface 22b is a substantially cylindrical curved surface extending around the second central axis Ax2 and facing approximately radially inward. In other words, the inner circumferential surface 22b faces the first central axis Ax1 and the second central axis Ax2. The inner circumferential surface 22b faces the outer circumferential surface 21b of the inner gear 21 at a distance. The outer circumferential surface 22c is located on the opposite side of the inner circumferential surface 22b and is a substantially cylindrical curved surface extending around the second central axis Ax2. The outer circumferential surface 22c faces approximately radially outward.

[0024] A plurality of internal teeth 27 are provided on the inner peripheral surface 22b of the outer gear 22. The internal teeth 27 protrude from the inner peripheral surface 22b and are arranged approximately in the circumferential direction. Therefore, the inner peripheral surface 22b forms the tooth bottoms of the internal teeth 27. The multiple internal teeth 27 mesh with the multiple external teeth 25.

[0025] A plurality of gaps 29 are provided between the plurality of external teeth 25 and the plurality of internal teeth 27. The inner gear 21 on which the external teeth 25 are provided is eccentric with respect to the outer gear 22 on which the internal teeth 27 are provided. Therefore, the sizes of the plurality of gaps 29 are different from one another.

[0026] The key 13 is attached to the shaft 11 and protrudes radially outward from the shaft 11. The key 13 fits into the key groove 24. This allows the key 13 to transmit the rotation of the shaft 11 to the inner gear 21. In other words, the inner gear 21 can rotate integrally with the shaft 11 around the first central axis Ax1.

[0027] 1, the housing 14 includes a cylinder 31, a plug 32, a casing 33, and two ring seals 34. The cylinder 31, the plug 32, and the casing 33 are aligned in the axial direction. The casing 33 is located between the cylinder 31 and the plug 32.

[0028] As shown in FIG. 2, the casing 33 is formed in a substantially annular shape extending around a third central axis Ax3. That is, the third central axis Ax3 is the central axis of the casing 33. The third central axis Ax3 extends substantially parallel to the first central axis Ax1 and the second central axis Ax2 and is slightly spaced radially from the second central axis Ax2. Therefore, the axial direction is also a direction extending along the third central axis Ax3. The radial direction is approximately equal to a direction perpendicular to the third central axis Ax3. The circumferential direction is approximately equal to a direction around the third central axis Ax3. As shown in FIG. 3, the casing 33 has two end faces 33a and an inner circumferential surface 33b.

[0029] The two end faces 33a are provided at both ends of the casing 33 in the axial direction. That is, the end faces 33a are end faces of the casing 33 in the axial direction. The end faces 33a are formed substantially flat and face the axial direction. The end face 33a of the casing 33 is positioned on substantially the same plane as the end face 22a of the outer gear 22.

[0030] The inner circumferential surface 33b is a generally cylindrical curved surface extending around the third central axis Ax3 and facing inward in the generally radial direction. In other words, the inner circumferential surface 33b faces the first central axis Ax1, the second central axis Ax2, and the third central axis Ax3.

[0031] 1, the housing 14 is provided with a rotor chamber 35, a suction passage 36, and a discharge passage 37. The rotor chamber 35 is provided inside the housing 14. The rotor chamber 35 is defined by the cylinder 31, the plug 32, and the inner circumferential surface 33b of the casing 33. A portion of the shaft 11 and the rotor unit 12 are housed in the rotor chamber 35.

[0032] The suction passage 36 and the discharge passage 37 are provided in the cylinder 31 and communicate with the rotor chamber 35. The discharge passage 37 is spaced apart from the suction passage 36 in a substantially radial direction. In the radial direction, the first central axis Ax1, the second central axis Ax2, the third central axis Ax3, and the shaft 11 are located between the suction passage 36 and the discharge passage 37. Note that the positions of the suction passage 36 and the discharge passage 37 are not limited to this example.

[0033] 2, the rotor unit 12 is disposed inside the inner circumferential surface 33b. That is, the inner circumferential surface 33b surrounds the outer gear 22. The diameter of the inner circumferential surface 33b is larger than the diameter of the outer circumferential surface 22c of the outer gear 22. Therefore, the outer circumferential surface 22c of the outer gear 22 faces the inner circumferential surface 33b of the casing 33 with a gap G therebetween.

[0034] The outer peripheral surface 22c of the outer gear 22 extends around the second central axis Ax2. The inner peripheral surface 33b of the casing 33 extends around the third central axis Ax3. That is, the outer peripheral surface 22c of the outer gear 22 is eccentric with respect to the inner peripheral surface 33b of the casing 33. For this reason, the distance between the outer peripheral surface 22c and the inner peripheral surface 33b in the gap G is not constant but gradually changes.

[0035] Two recesses 38 are provided in the casing 33. The recesses 38 are recessed from the inner peripheral surface 33b of the casing 33 at positions spaced apart from each other in the circumferential direction and communicate with the rotor chamber 35. The recesses 38 open toward the outer peripheral surface 22c of the outer gear 22 housed in the rotor chamber 35.

[0036] 1, the two ring seals 34 and the rotor unit 12 are aligned in the axial direction. One of the two ring seals 34 is located between the cylinder 31 and the rotor unit 12. The other of the two ring seals 34 is located between the plug 32 and the rotor unit 12. The rotor unit 12 is located between the two ring seals 34. The two ring seals 34 are formed in mirror symmetry with respect to an imaginary plane that is approximately perpendicular to the first central axis Ax1.

[0037] The ring seals 34 are mainly made of metal such as iron, but may also be made of other materials such as synthetic resin. As shown in Fig. 3, each of the two ring seals 34 has a wall 41, an outer peripheral protrusion 42, a partition protrusion 43, and a converging protrusion 44.

[0038] The wall 41 is formed in a disk shape that is approximately perpendicular to the first central axis Ax1. The wall 41 is spaced apart from the rotor unit 12 in the axial direction. The wall 41 has a side surface 41a. The side surface 41a is formed to be approximately flat and faces the axial direction. The side surface 41a faces the rotor unit 12 with a gap therebetween. For example, the side surface 41a faces the end surface 21a of the inner gear 21 and the end surface 22a of the outer gear 22.

[0039] 4 is a front view showing the ring seal 34 of this embodiment. As shown in FIG. 4, a wall 41 is provided with an insertion hole 45, an intake port 46, and a plurality of discharge ports 47. The insertion hole 45 penetrates the wall 41 in the axial direction along the first central axis Ax1 and opens to the side surface 41a. The shaft 11 extends through the insertion hole 45.

[0040] The suction port 46 and the discharge port 47 each penetrate the wall 41 in the axial direction and open to the side surface 41a. The suction port 46 communicates with the suction passage 36 of the cylinder 31. The discharge port 47 communicates with the discharge passage 37 of the cylinder 31.

[0041] The outer peripheral protrusion 42 protrudes from the edge of the side surface 41a of the wall 41 on the radially outer side toward the end surface 33a of the casing 33. The outer peripheral protrusion 42 is formed in a substantially annular shape extending around the third central axis Ax3.

[0042] FIG. 5 is a cross-sectional view that schematically shows a portion of the outer gear 22, the casing 33, and the ring seal 34 of this embodiment. As shown in FIG. 5, the outer peripheral protrusion 42 has a sealing surface 42a. The sealing surface 42a is located at the end of the outer peripheral protrusion 42 in the axial direction and faces the end face 33a of the casing 33 with a small gap therebetween. For example, the distance between the sealing surface 42a and the end face 33a is several μm. The sealing surface 42a may also contact the end face 33a.

[0043] The inner diameter of the sealing surface 42a of the outer peripheral convex portion 42 is larger than the diameter of the inner peripheral surface 33b of the casing 33. Therefore, the sealing surface 42a of the outer peripheral convex portion 42 is spaced radially outward from the inner peripheral surface 33b of the casing 33. In other words, the outer peripheral convex portion 42 is spaced farther from the first central axis Ax1 than the inner peripheral surface 33b of the casing 33. Note that the inner diameter of the sealing surface 42a and the diameter of the inner peripheral surface 33b of the casing 33 may be the same.

[0044] 3, the partitioning protrusion 43 protrudes from the side surface 41a of the wall 41 toward the rotor unit 12. The partitioning protrusion 43 has a sealing surface 43a. The sealing surface 43a is located at the end of the partitioning protrusion 43 in the axial direction and faces the rotor unit 12 with a small gap therebetween. Note that the sealing surface 43a may temporarily come into contact with the rotor unit 12.

[0045] 4, the partitioning protrusion 43 extends in a substantially C-shape so as to surround the shaft 11 and the insertion hole 45. Both ends of the partitioning protrusion 43 are connected to the outer peripheral protrusion 42. The sealing surface 43a of the partitioning protrusion 43 and the sealing surface 42a of the outer peripheral protrusion 42 are continuous with each other.

[0046] 2, the partitioning protrusion 43 divides the rotor chamber 35 into a low-pressure region 35L and a high-pressure region 35H between the wall 41 and the rotor unit 12. As shown in FIG. 1, the low-pressure region 35L communicates with the suction passage 36. The high-pressure region 35H communicates with the discharge passage 37.

[0047] 2, in this embodiment, the shaft 11 and the insertion holes 23, 45 are provided in the low pressure region 35L. The shaft 11 and the insertion holes 23, 45 may also be provided in the high pressure region 35H.

[0048] The low pressure region 35L and the high pressure region 35H may be in communication with each other through a small gap between the rotor unit 12 and the partition convex portion 43. However, this small gap is set narrow enough to maintain a pressure difference between the low pressure region 35L and the high pressure region 35H while the gear pump device 10 is in operation.

[0049] The multiple external teeth 25 of the inner gear 21 and the multiple internal teeth 27 of the outer gear 22 are arranged across the low pressure region 35L and the high pressure region 35H. Therefore, the external teeth 25 and the internal teeth 27 circulate between the low pressure region 35L and the high pressure region 35H as the inner gear 21 and the outer gear 22 rotate.

[0050] When the shaft 11 rotates the inner gear 21 in the first circumferential direction Dc1, the outer gear 22 also rotates about the second central axis Ax2 approximately in the first circumferential direction Dc1 due to the meshing of the external teeth 25 and the internal teeth 27. As a result, the gap 29 between the external teeth 25 and the internal teeth 27 moves approximately in the first circumferential direction Dc1 while expanding and contracting. The gap 29 moves from the low-pressure region 35L to the high-pressure region 35H.

[0051] A fluid such as brake fluid is supplied from the suction passage 36 to the low-pressure region 35L through the suction port 46. The brake fluid flows into the gap 29 in the low-pressure region 35L. As the inner gear 21 and the outer gear 22 rotate in the first circumferential direction Dc1, the rotor unit 12 transports the brake fluid in the gap 29 from the low-pressure region 35L to the high-pressure region 35H. The brake fluid transported to the high-pressure region 35H is discharged from the gap 29 through the discharge port 47 to the discharge passage 37.

[0052] The rotor chamber 35 further includes a first boundary region 35B1 and a second boundary region 35B2. The first boundary region 35B1 and the second boundary region 35B2 are located between the low pressure region 35L and the high pressure region 35H. The first boundary region 35B1 and the second boundary region 35B2 are spaced apart from each other in the circumferential direction.

[0053] The first boundary region 35B1 includes, among the gaps 29 that move in the first circumferential direction Dc1 from the low-pressure region 35L to the high-pressure region 35H, the gaps 29 that are located between the partitioning protrusions 43 of the two ring seals 34. The seal surfaces 43a of the partitioning protrusions 43 face the first boundary region 35B1. The volume of the gaps 29 is maximum in the first boundary region 35B1.

[0054] The second boundary region 35B2 includes, among the gaps 29 that move from the high-pressure region 35H to the low-pressure region 35L in the first circumferential direction Dc1, the gaps 29 that are located between the partitioning protrusions 43 of the two ring seals 34. The seal surfaces 43a of the partitioning protrusions 43 face the second boundary region 35B2. In the second boundary region 35B2, the volume of the gaps 29 is minimum.

[0055] The convergent convex portion 44 protrudes from the side surface 41a of the wall 41 toward the outer gear 22 in the high-pressure region. The convergent convex portion 44 is connected to the outer peripheral convex portion 42 and is spaced apart from the partitioning convex portion. For example, the convergent convex portion 44 extends from the outer peripheral convex portion 42 toward the third central axis Ax3.

[0056] Each of the two recesses 38 houses one of the two outer circumferential seals 15. The two recesses 38 and the two outer circumferential seals 15 are each located between the low pressure region 35L and the high pressure region 35H in the circumferential direction.

[0057] Each of the two peripheral seals 15 includes a seal member 51 and an elastic body 52. ​​The seal member 51 may also be called a chip seal. The elastic body 52 may also be called a chip ball.

[0058] The seal member 51 is made of, for example, synthetic resin. However, the material of the seal member 51 is not limited to this example. The seal member 51 is formed in the shape of a block having a substantially triangular cross section.

[0059] The elastic body 52 is made of an elastomer such as synthetic rubber. The elastic body 52 is not limited to this example and may be another elastic body such as a coil spring. The elastic body 52 of this embodiment is formed in a substantially spherical or substantially ellipsoidal shape. The shape of the elastic body 52 is not limited to this example and may be formed in, for example, a substantially cylindrical shape.

[0060] The seal member 51 is interposed between the outer gear 22 and the elastic body 52. ​​The elastic body 52 is compressed between the casing 33 and the seal member 51, and presses the seal member 51 toward the outer peripheral surface 22c of the outer gear 22 by its elastic force.

[0061] The seal member 51 abuts against the outer peripheral surface 22c, thereby sealing the low pressure region 35L and the high pressure region 35H between the outer peripheral surface 22c of the outer gear 22 and the inner peripheral surface 33b of the casing 33. Note that the seal member 51 and the outer peripheral surface 22c may be slightly spaced apart from each other, for example, via brake fluid.

[0062] The two recesses 38 are spaced apart from each other by an angle less than 180° around the second central axis Ax2. Therefore, the two outer seals 15 press the outer gear 22 toward a point on the inner circumferential surface 33b of the casing 33 located in the high-pressure region 35H. The gap G has a minimum portion Gm near the point on the inner circumferential surface 33b.

[0063] The minimum portion Gm is located in the high-pressure region 35H of the gap G, and is the portion where the distance between the inner circumferential surface 33b of the casing 33 and the outer circumferential surface 22c of the outer gear 22 is the smallest. The gap G tapers toward the minimum portion Gm. The position of the minimum portion Gm is determined by, for example, the differential pressure (discharge pressure) between the low-pressure region 35L and the high-pressure region 35H, the force with which the two outer circumferential seals 15 press against the outer gear 22, and various other conditions.

[0064] Fig. 6 is a front view showing a portion of the ring seal 34 of this embodiment. Fig. 7 is a cross-sectional view schematically showing a portion of the outer gear 22 and the ring seal 34 of this embodiment along line F7-F7 in Fig. 6. As shown in Fig. 7, the converging protrusion 44 has a sealing surface 44a and two inclined surfaces 44b, 44c.

[0065] The sealing surface 44a is located at the end of the converging protrusion 44 in the axial direction. As shown in Fig. 2, the sealing surface 44a of the converging protrusion 44 extends from the sealing surface 42a of the outer peripheral protrusion 42 toward the third central axis Ax3, crossing the inner peripheral surface 33b of the casing 33, the gap G, and the outer peripheral surface 22c of the outer gear 22. The sealing surface 44a of the converging protrusion 44 and the sealing surface 42a of the outer peripheral protrusion 42 are continuous with each other.

[0066] The radial length (width) of the converging protrusion 44 is set to be short. For example, the radial length (width) of the sealing surface 44a of the converging protrusion 44 is shorter than the radial length (width) of the sealing surface 42a of the outer peripheral protrusion 42. The sealing surface 44a of the converging protrusion 44 is spaced radially outward from the inner peripheral surface 22b of the outer gear 22.

[0067] 5, the sealing surface 44a faces the end face 22a of the outer gear 22, the end face 33a of the casing 33, and a part of the gap G including the minimum portion Gm, with a small gap therebetween. The sealing surface 44a may contact the casing 33, or may contact the outer gear 22 temporarily.

[0068] 7, the converging protrusion 44 protrudes from a portion of the side surface 41a in the circumferential direction. Meanwhile, the other portion of the side surface 41a in the circumferential direction is farther away from the outer gear 22 than the sealing surface 44a of the converging protrusion 44.

[0069] As shown in FIG. 2 , a portion of the side surface 41a of the wall 41 adjacent to the convergent protrusion 44 around the first central axis Ax1 extends from the outer peripheral protrusion 42 across the inner peripheral surface 33b of the casing 33, the gap G, and the outer peripheral surface 22c of the outer gear 22 toward the third central axis Ax3. That is, the portion of the side surface 41a adjacent to the convergent protrusion 44 around the first central axis Ax1 is spaced from the rotor unit 12 in the axial direction and faces the end surface 22a of the outer gear 22, the end surface 33a of the casing 33, and the gap G. The side surface 41a faces a part of the gap G excluding the minimum portion Gm. In the circumferential direction, the area of ​​the side surface 41a facing the gap G is larger than the area of ​​the sealing surface 44a facing the gap G.

[0070] As shown in Fig. 7, the inclined surface 44b is connected to the edge of the sealing surface 44a in the first circumferential direction Dc1 and the side surface 41a. The inclined surface 44b is inclined relative to the sealing surface 44a and the side surface 41a. The distance between the inclined surface 44b and the outer gear 22 narrows toward the second circumferential direction Dc2. The second circumferential direction Dc2 is opposite to the first circumferential direction Dc1 and is an example of a reverse direction.

[0071] The inclined surface 44c is connected to the edge of the sealing surface 44a in the second circumferential direction Dc2 and the side surface 41a. The inclined surface 44c is inclined with respect to the sealing surface 44a and the side surface 41a. The distance between the inclined surface 44c and the outer gear 22 narrows in the first circumferential direction Dc1.

[0072] 6, a plurality of grooves 60 are provided in the seal surface 44a. The grooves 60 may also be referred to as texturing. The grooves 60 communicate with a small gap between the seal surface 44a and the end face 22a of the outer gear 22. The plurality of grooves 60 are spaced apart from the edge of the seal surface 44a.

[0073] The groove 60 is provided in the sealing surface 44a by, for example, laser processing. The groove 60 may be formed by other methods. As shown in Fig. 7, the length (depth) of the groove 60 in the axial direction is smaller than the distance between the side surface 41a of the wall 41 and the end surface 22a of the outer gear 22. For example, the depth of the groove 60 is smaller than 10% of the distance between the side surface 41a and the end surface 22a, but is not limited to this.

[0074] 6, each of the plurality of grooves 60 is formed, for example, in a substantially V-shape. That is, each of the plurality of grooves 60 has two linear portions 61, 62. Each of the linear portions 61, 62 is a groove that extends linearly along the sealing surface 44a. One end of the linear portion 61 and one end of the linear portion 62 are connected to each other.

[0075] The two straight line portions 61, 62 extend such that the groove 60 tapers in the first circumferential direction Dc1. That is, the cross-sectional area of ​​the groove 60 decreases in the first circumferential direction Dc1. Note that the groove 60 may be formed in another shape in which the cross-sectional area decreases in the first circumferential direction Dc1.

[0076] Two adjacent grooves 60 overlap in the first circumferential direction Dc1. In other words, a portion of one groove 60 and a portion of another groove 60 are disposed at the same position in the circumferential direction. Note that the grooves 60 are not limited to this example.

[0077] When the shaft 11 rotates the inner gear 21 in the first circumferential direction Dc1, the outer gear 22 also rotates about the second central axis Ax2 due to the meshing of the external teeth 25 and the internal teeth 27. In the gap G between the outer peripheral surface 22c of the outer gear 22 and the inner peripheral surface 33b of the casing 33, the brake fluid flows approximately in the first circumferential direction Dc1 as the outer gear 22 rotates due to, for example, viscosity.

[0078] The brake fluid flowing in the first circumferential direction Dc1 in the gap G is drawn into the minimum pressure portion Gm. As a result, the pressure of the brake fluid (oil film pressure) increases at the minimum pressure portion Gm due to a wedge effect. The oil film pressure causes the outer peripheral surface 22c of the outer gear 22 to separate from the inner peripheral surface 33b of the casing 33, leaving the minimum pressure portion Gm. Note that when the rotor unit 12 is stopped, the outer peripheral surface 22c of the outer gear 22 may come into contact with the inner peripheral surface 33b of the casing 33.

[0079] The sealing surface 44a of the converging protrusion 44 faces the minimum portion Gm with a small gap therebetween, so that the sealing surface 44a essentially blocks the minimum portion Gm in the axial direction, thereby reducing leakage of brake fluid from the minimum portion Gm in the axial direction.

[0080] The position of the minimum pressure portion Gm may vary (change) circumferentially due to, for example, friction caused by contact between various components, the rotational speed of the inner gear 21 and the outer gear 22, the pressure difference between the low-pressure region 35L and the high-pressure region 35H, variations in the dimensions of various components, and various other conditions. The sealing surface 44a of the converging protrusion 44 extends around the third central axis Ax3 so as to axially block the minimum pressure portion Gm even if the position of the minimum pressure portion Gm changes. In other words, the sealing surface 44a of the converging protrusion 44 extends around the third central axis Ax3 so as to axially cover the area of ​​the inner circumferential surface 33b of the casing 33 against which the outer gear 22 may be pressed.

[0081] 2, the sealing surface 44a of the converging protrusion 44 is provided within a range R of 60° in the first circumferential direction Dc1 and the second circumferential direction Dc2 from the position of the minimum point Gm (or the contact point between the outer gear 22 and the casing 33) when the rotor unit 12 is stopped. The position and length of the sealing surface 44a around the third central axis Ax3 are set within the range R based on, for example, the various conditions described above for the gear pump device 10. Note that the position and length of the sealing surface 44a around the third central axis Ax3 are not limited to this example.

[0082] The sealing surface 44a of the converging protrusion 44 prevents the brake fluid from leaking axially from the minimum pressure portion Gm, thereby making the axial distribution of the oil film pressure at the minimum pressure portion Gm more uniform, thereby preventing the outer gear 22 from tilting due to uneven oil film pressure.

[0083] As described above, in a portion in the circumferential direction where the wedge effect occurs, the sealing surface 44a of the converging protrusion 44 faces the gap G and the outer gear 22. On the other hand, in other portions in the circumferential direction where the wedge effect does not occur or is small, the side surface 41a of the wall 41 faces the outer gear 22. Because the side surface 41a is farther away from the outer gear 22 than the sealing surface 44a, loss due to sliding between the side surface 41a and the outer gear 22 and loss caused by shear force due to the viscosity of the brake fluid between the side surface 41a and the outer gear 22 are less likely to occur. Therefore, the ring seal 34 can reduce sliding loss and viscous shear loss.

[0084] When the outer gear 22 rotates, the brake fluid in the space between the end face 22a of the outer gear 22 and the inclined surface 44c of the convex portion 44 also flows in the first circumferential direction Dc1. As a result, the brake fluid is drawn into the small gap between the seal surface 44a and the end face 22a, and the wedge effect increases the oil film pressure.

[0085] Furthermore, in the small gap between the end face 22a and the seal surface 44a, the brake fluid flows through the multiple grooves 60. Therefore, the brake fluid flowing through the straight portion 61 and the brake fluid flowing through the straight portion 62 collide with each other at the tip ends 60a of the grooves 60 in the first circumferential direction Dc1. The collision of the brake fluids increases the oil film pressure in the small gap between the seal surface 44a and the end face 22a.

[0086] The plurality of grooves 60 are aligned in the first circumferential direction Dc1 and overlap with the first circumferential direction Dc1. Therefore, the brake fluids collide with each other multiple times in the first circumferential direction Dc1, causing a cumulative increase in oil film pressure.

[0087] The cross-sectional area of ​​the groove 60 decreases in the first circumferential direction Dc1, and the brake fluid flows in the first circumferential direction Dc1. As a result, the brake fluids collide strongly with each other at the tip 60a, and the oil film pressure increases efficiently.

[0088] As described above, the converging protrusion 44 increases the oil film pressure in the small gap between the end face 22a and the seal surface 44a by means of the inclined surface 44c and the groove 60. This allows the converging protrusion 44 to suppress loss due to sliding between the seal surface 44a and the outer gear 22.

[0089] The sealing surface 44a of the converging protrusion 44 supports the outer gear 22 via the brake fluid. As a result, the converging protrusion 44 suppresses tilting of the outer gear 22, and thus can suppress losses due to sliding between the outer gear 22 and other components. Note that a convex portion other than the converging protrusion 44 may suppress tilting of the outer gear 22.

[0090] In the gear pump apparatus 10 according to the present embodiment described above, the housing 14 has an inner circumferential surface 33b, a side surface 41a, and a converging protrusion 44. The cylindrical inner circumferential surface 33b surrounds the outer gear 22. The side surface 41a is spaced apart from the rotor unit 12 in the axial direction along the first central axis Ax1 and faces the rotor unit 12. The converging protrusion 44 protrudes from the side surface 41a toward the outer gear 22. The outer gear 22 has a cylindrical outer circumferential surface 22c that faces the inner circumferential surface 33b across a gap G and is eccentric relative to the inner circumferential surface 33b. The converging protrusion 44 has a sealing surface 44a. The sealing surface 44a faces the outer gear 22 and a minimum portion Gm of the gap G where the distance between the inner circumferential surface 33b and the outer circumferential surface 22c is smallest. A portion of the side surface 41a adjacent to the converging protrusion 44 around the first central axis Ax1 is spaced apart from the rotor unit 12 in the axial direction relative to the sealing surface 44a and faces the gap G.

[0091] When the inner gear 21 rotates in a first circumferential direction Dc1 around the first central axis Ax1, the outer gear 22 also rotates approximately in the first circumferential direction Dc1 due to the meshing of the external teeth 25 and the internal teeth 27. As the outer gear 22 rotates, the brake fluid in the rotor chamber 35 also flows in the first circumferential direction Dc1, for example, through the gap G. Because the inner circumferential surface 33b and the outer circumferential surface 22c are eccentric to each other, the gap G tapers toward the minimum portion Gm. Therefore, the brake fluid flows into the minimum portion Gm, increasing the pressure (oil film pressure) of the brake fluid due to a wedge effect. The sealing surface 44a of the converging protrusion 44 covers the minimum portion Gm in the vicinity thereof, thereby preventing the brake fluid from leaking axially from the minimum portion Gm. Therefore, the gear pump device 10 can prevent a decrease in oil film pressure at the minimum part Gm due to brake fluid leakage, and can therefore prevent sliding loss from occurring between the inner circumferential surface 33b and the outer circumferential surface 22c. Meanwhile, the side surface 41a faces the outer gear 22 and the gap G, farther away from the seal surface 44a. Therefore, the gear pump device 10 can prevent sliding loss and viscous shear loss from occurring between the side surface 41a and the outer gear 22. As a result, the gear pump device 10 can improve its efficiency.

[0092] The housing 14 has a casing 33 and a ring seal 34. The casing 33 has an inner circumferential surface 33b and an end surface 33a in the axial direction. The ring seal 34 has a side surface 41a, a partitioning protrusion 43, a converging protrusion 44, and an outer circumferential protrusion 42. The outer circumferential protrusion 42 protrudes from the side surface 41a toward the end surface 33a, is farther away from the first central axis Ax1 than the inner circumferential surface 33b, and is connected to the converging protrusion 44.

[0093] The outer peripheral protrusion 42 protrudes toward the end face 33a of the casing 33, thereby substantially sealing the gap between the outer peripheral protrusion 42 and the end face 33a of the casing 33. The converging protrusion 44 extends from the outer peripheral protrusion 42 across (transverse to) the gap G between the inner peripheral surface 33b of the casing 33 and the outer peripheral surface 22c of the outer gear 22. Therefore, the gear pump device 10 can prevent the brake fluid in the minimum part Gm from leaking through the gap between the seal surface 44a and the casing 33.

[0094] The rotor unit 12 transports brake fluid in a gap 29 provided between the plurality of external teeth 25 and the plurality of internal teeth 27 from the low-pressure region 35L to the high-pressure region 35H as the inner gear 21 rotates in a first circumferential direction Dc1 about the first central axis Ax1. A groove 60 whose cross-sectional area decreases in the first circumferential direction Dc1 is provided in the sealing surface 44a.

[0095] The brake fluid converges in the first circumferential direction Dc1 as it flows through the grooves 60. The brake fluid collides with each other at the tips 60a of the grooves 60 in the first circumferential direction Dc1, increasing the oil film pressure between the seal surface 44a and the outer gear 22. This allows the gear pump device 10 to suppress sliding loss between the converging protrusion 44 and the outer gear 22, thereby improving efficiency.

[0096] The converging protrusion 44 has a slope 44c. The slope 44c is connected to an edge of the sealing surface 44a in a second circumferential direction Dc2 opposite to the first circumferential direction Dc1. The distance between the slope 44c and the outer gear 22 narrows in the first circumferential direction Dc1.

[0097] The space between the inclined surface 44c and the outer gear 22 tapers in the first circumferential direction Dc1. Therefore, the brake fluid flows in the first circumferential direction Dc1, and a wedge effect increases the oil film pressure between the convergent convex portion 44 and the outer gear 22. Therefore, the gear pump device 10 can suppress sliding loss between the convergent convex portion 44 and the outer gear 22, thereby improving efficiency.

[0098] In the above-described gear pump device 10, the edge of the sealing surface 44a in the second circumferential direction Dc2 extends linearly in a direction perpendicular to the third central axis Ax3. However, the edge of the sealing surface 44a in the second circumferential direction Dc2 may be V-shaped or U-shaped, tapering toward the first circumferential direction Dc1. In this case, the brake fluid flows along the edge of the sealing surface 44a, thereby increasing the oil film pressure.

[0099] The gear pump device according to at least one embodiment described above, for example, includes an inner gear rotatable about a rotation axis and an outer gear surrounding the inner gear, and includes a rotor unit in which a plurality of external teeth provided on the inner gear mesh with a plurality of internal teeth provided on the outer gear, a rotor chamber accommodating the rotor unit, a suction passage communicating with the rotor chamber, and a discharge passage communicating with the rotor chamber, and includes a cylindrical inner circumferential surface facing the rotation axis and surrounding the outer gear, a side surface spaced apart from the rotor unit in the axial direction along the rotation axis and facing the rotor unit, and a projection protruding from the side surface toward the rotor unit. The housing includes a partitioning protrusion that divides the rotor chamber into a low-pressure region communicating with the suction passage and a high-pressure region communicating with the discharge passage, and a converging protrusion that protrudes from the side surface toward the outer gear. The outer gear has a cylindrical outer surface that faces the inner circumferential surface with a gap and is eccentric with respect to the inner circumferential surface. The converging protrusion has a sealing surface that faces the outer gear and a portion of the gap where the distance between the inner circumferential surface and the outer circumferential surface is smallest. A portion of the side surface adjacent to the converging protrusion around the rotation axis is spaced apart from the rotor unit in the axial direction relative to the sealing surface and faces the gap. Thus, for example, when the inner gear rotates in a rotational direction around the rotational axis, the outer gear also rotates approximately in the rotational direction due to meshing between the external teeth and the internal teeth. As the outer gear rotates, fluid in the rotor chamber also flows in the rotational direction, for example, through the gap. Because the inner and outer circumferential surfaces are eccentric to each other, the gap tapers toward the point where the distance between the inner and outer circumferential surfaces is smallest (the minimum portion). As a result, fluid flows into the minimum portion, increasing the fluid pressure (oil film pressure) through a wedge effect. The sealing surface of the converging convex portion covers the minimum portion in the vicinity, preventing fluid from leaking axially from the minimum portion. Therefore, the gear pump device can prevent a decrease in oil film pressure at the minimum portion due to fluid leakage, and ultimately prevent frictional loss from occurring between the inner and outer circumferential surfaces. Meanwhile, the side surface faces the outer gear and the gap, farther away from the sealing surface. Therefore, the gear pump device can prevent frictional loss and viscous shear loss from occurring between the side surface and the outer gear.As a result, the gear pump device can improve efficiency.

[0100] In the gear pump device, for example, the housing includes a casing and a ring seal. The casing has an inner circumferential surface and an end surface in the axial direction. The ring seal includes the side surface, the partitioning convex portion, the converging convex portion, and an outer circumferential convex portion that protrudes from the side surface toward the end surface, is farther from the rotation shaft than the inner circumferential surface, and is connected to the converging convex portion. The seal surface faces the end surface. Therefore, for example, the outer circumferential convex portion protrudes toward the end surface of the casing, thereby substantially sealing the gap between the outer circumferential convex portion and the end surface of the casing. The converging convex portion extends from the outer circumferential convex portion across (transversely) the gap between the inner circumferential surface of the casing and the outer circumferential surface of the outer gear. This prevents fluid from leaking through the gap between the seal surface and the casing.

[0101] In the above gear pump device, as an example, the rotor unit transports fluid in gaps between the multiple external teeth and the multiple internal teeth from the low-pressure region to the high-pressure region as the inner gear rotates in a rotational direction about the rotation axis, and the seal surface is provided with grooves whose cross-sectional area decreases in the rotational direction. Thus, as an example, the fluid flows through the grooves and converges in the rotational direction. Fluids collide with each other at the ends of the grooves in the rotational direction, increasing the oil film pressure between the seal surface and the outer gear. This allows the gear pump device to suppress sliding loss between the convergent convex portion and the outer gear, thereby improving efficiency.

[0102] In the above-described gear pump device, as an example, the rotor unit transports fluid in a gap between the plurality of external teeth and the plurality of internal teeth from the low-pressure region to the high-pressure region as the inner gear rotates in a rotational direction around the rotation axis, and the convergent convex portion has a slope connected to an edge of the sealing surface in a reverse direction opposite to the rotational direction, and the distance between the slope and the outer gear narrows toward the rotational direction. Therefore, as an example, the space between the slope and the outer gear tapers in the rotational direction. Therefore, as the fluid flows in the rotational direction, a wedge effect increases the oil film pressure between the convergent convex portion and the outer gear. Therefore, the gear pump device can suppress sliding loss between the convergent convex portion and the outer gear, thereby improving efficiency.

[0103] While the embodiments of the present invention have been described above, the above-described embodiments and modifications are merely examples and are not intended to limit the scope of the invention. The above-described embodiments and modifications can be implemented in various other forms, and various omissions, substitutions, combinations, and modifications can be made without departing from the spirit of the invention. Furthermore, the configurations and shapes of each embodiment and each modification can be partially interchanged. [Explanation of symbols]

[0104] 10...gear pump device, 12...rotor unit, 14...housing, 21...inner gear, 22...outer gear, 22c...outer peripheral surface, 25...external teeth, 27...internal teeth, 29...gap, 33...casing, 33a...end face, 33b...inner peripheral surface, 34...ring seal, 35...rotor chamber, 35L...low pressure region, 35H...high pressure region, 36...suction passage, 37...discharge passage, 41a...side face, 42...outer peripheral convex portion, 43...compartment convex portion, 44...converging convex portion, 44a...seal surface, 44c...inclined surface, 60...groove, Ax1...first central axis (rotation axis), Dc1...first circumferential direction (rotation direction), Dc2...second circumferential direction (reverse direction), G...gap, Gm...minimum portion (portion with smallest distance).

Claims

1. a rotor unit including an inner gear rotatable about a rotation axis and an outer gear surrounding the inner gear, wherein a plurality of external teeth provided on the inner gear mesh with a plurality of internal teeth provided on the outer gear; a housing provided with a rotor chamber that accommodates the rotor unit, an intake passage that communicates with the rotor chamber, and a discharge passage that communicates with the rotor chamber, the housing having a cylindrical inner circumferential surface that faces the rotation shaft and surrounds the outer gear, a side surface that is spaced away from the rotor unit in the axial direction along the rotation shaft and faces the rotor unit, a partitioning convex portion that projects from the side surface toward the rotor unit and partitions the rotor chamber into a low-pressure region that communicates with the intake passage and a high-pressure region that communicates with the discharge passage, and a converging convex portion that projects from the side surface toward the outer gear; Equipped with the outer gear has a cylindrical outer peripheral surface that faces the inner peripheral surface with a gap therebetween and is eccentric with respect to the inner peripheral surface, the converging protrusion has a sealing surface facing the outer gear and a portion of the gap where the distance between the inner circumferential surface and the outer circumferential surface is smallest, a portion of the side surface adjacent to the converging protrusion around the rotation axis is spaced apart from the rotor unit in the axial direction relative to the seal surface and faces the gap; Gear pump device.

2. the housing includes a casing and a ring seal; the casing has the inner circumferential surface and an end surface in the axial direction, the ring seal has the side surface, the partitioning convex portion, the converging convex portion, and an outer peripheral convex portion that protrudes from the side surface toward the end surface, is spaced further from the rotation shaft than the inner peripheral surface, and is connected to the converging convex portion, The sealing surface faces the end surface.

2. The gear pump device of claim 1.

3. the rotor unit transports fluid in gaps provided between the plurality of external teeth and the plurality of internal teeth from the low-pressure region to the high-pressure region as the inner gear rotates in a rotational direction around the rotation axis; The seal surface is provided with a groove whose cross-sectional area decreases in the rotation direction.

2. The gear pump device of claim 1.

4. the rotor unit transports fluid in gaps provided between the plurality of external teeth and the plurality of internal teeth from the low-pressure region to the high-pressure region as the inner gear rotates in a rotational direction around the rotation axis; the converging protrusion has a slope connected to an edge of the seal surface in a reverse direction opposite to the rotation direction, and the distance between the slope and the outer gear narrows toward the rotation direction.

2. The gear pump device of claim 1.

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