Internal gear pump

Abstract

An internal gear pump (100A) comprises: a pump unit (10) that discharges oil by the rotation of a drive shaft (1A); and a housing (20A) that accommodates the pump unit (10). The pump unit (10) includes: an inner rotor (11) having a plurality of external teeth (11a) and connected to the drive shaft 1; and an outer rotor (12) having a plurality of internal teeth (12a), which come into sliding contact with the external teeth (11a), and disposed outside the inner rotor (11). The internal gear pump (100A) includes: a first volume chamber (R1) which faces the outer periphery of the outer rotor (12) in a discharge region (66), has a throttle (T) formed along the outer periphery, and into which hydraulic oil discharged from the pump unit (10) is guided; and a discharge passage (50) through which the oil that has passed through the throttle (T) is discharged from the first volume chamber (R1).

Description

Internal gear pump

[0001] The present invention relates to an internal gear pump.

[0002] JP 6096545B discloses an oil pump having an oil guide groove formed on the inner peripheral surface of the housing facing the outer peripheral surface of the outer rotor at the same circumferential position as the discharge port and communicating with a discharge passage. JP 2008-1251A discloses a pump device in which an introduction groove is formed on the inner peripheral surface of the cam ring over a predetermined angular range to introduce pump discharge pressure. JP 7-145785A discloses a trochoidal refrigerant compressor in which an oil groove is formed to introduce pressurized lubricating oil between the cylindrical bearing surface of the front housing and the sliding surface of the outer periphery of the outer rotor.

[0003] In the discharge region of an internal gear pump, the pump chamber defined by the inner rotor and outer rotor contracts while pressurizing the liquid. As a result, an unbalanced load acts on the inner rotor and the outer rotor in a direction that moves them away from each other in the discharge region. As a result, the clearance between the external gear of the inner rotor and the internal gear of the outer rotor in the suction region becomes small, which can deteriorate the sliding characteristics and torque.

[0004] The present invention has been made in view of the above-mentioned problems, and has an object to suitably reduce the influence of the unbalanced load generated in the ejection area.

[0005] According to one aspect of the present invention, there is provided an internal gear pump comprising: a pump section that discharges liquid as a drive shaft is rotated; and a housing that accommodates the pump section, wherein the pump section comprises an inner rotor having a plurality of external teeth and connected to the drive shaft; and an outer rotor having a plurality of internal teeth that are in sliding contact with the external teeth and arranged outside the inner rotor, and a throttling section that faces the outer periphery of the outer rotor in the discharge region and is formed along the outer periphery; a volume chamber into which liquid discharged from the pump section is guided; and a discharge passage that discharges liquid that has passed through the throttling section from the volume chamber.

[0006] Fig. 1 is a plan view of a pump section of an internal gear pump according to an embodiment of the present invention. Fig. 2 is a plan view of the pump section with the cover section removed. Fig. 3 is a plan view showing the back surface of the cover section. Fig. 4 is an enlarged view of a volume chamber. Fig. 5 is a plan view showing the back surface of the cover section in a first modified example. Fig. 6 is a plan view of the pump section and main body section in the first modified example. Fig. 7 is a cross-sectional view of the pump section and main body section in a second modified example. Fig. 8 is an enlarged view of a modified example of the volume chamber. Fig. 9 is an enlarged view of another modified example of the volume chamber. Fig. 10 is a view showing a modified example of a discharge passage.

[0007] Hereinafter, an internal gear pump according to an embodiment of the present invention will be described with reference to the drawings. The internal gear pump according to the embodiment of the present invention is mounted, for example, on a vehicle and discharges a coolant (liquid) for cooling an electric motor mounted on the vehicle, or discharges oil (liquid) for lubricating gears mounted on the vehicle. The internal gear pump may be used as a fluid pressure supply source that discharges a working fluid (liquid) for driving equipment. The internal gear pump may also be mounted on industrial machinery other than vehicles. In this embodiment, a case will be described in which oil, which is a viscous fluid, is used as the liquid discharged by the internal gear pump. However, instead of oil, for example, a water-soluble substitute liquid may be used.

[0008] An internal gear pump 100A according to this embodiment will be described with reference to Figures 1 to 4. Figures 1 and 2 are plan views of the pump section 10 of the internal gear pump 100A, and Figure 2 shows a plan view (a plan view of the pump section 10 and the main body section 30A of the housing 20A) with the cover section 40A removed. Figure 3 is a plan view showing the back surface of the cover section 40A that covers the pump section 10.

[0009] The internal gear pump 100A includes a pump unit 10 that discharges oil when a drive shaft 1 is rotated, and a housing 20A that accommodates the pump unit 10. The arrow in Figure 2 indicates the direction of rotation of the drive shaft 1.

[0010] As shown in FIG. 2 , the pump section 10 includes an inner rotor 11 to which the drive shaft 1 is connected, and an outer rotor 12 disposed outside the inner rotor 11. The inner rotor 11 and outer rotor 12 are housed in a housing 20A (specifically, a main body section 30A, described later), are eccentrically disposed relative to each other, and are covered by a cover section 40A of the housing 20A. Specifically, the center of the inner rotor 11 coincides with the center of the drive shaft 1, and the center of the outer rotor 12 is offset downward from the drive shaft 1 in FIGS. 1 and 2 . The inner rotor 11 has a plurality of external teeth 11 a on its outer peripheral surface, and the outer rotor 12 has a plurality of internal teeth 12 a on its inner peripheral surface that slide against the external teeth 11 a. The external teeth 11 a and the internal teeth 12 a have different numbers of teeth, and a pump chamber 13 is defined by adjacent external teeth 11 a of the inner rotor 11 and the internal teeth 12 a of the outer rotor 12. A plurality of pump chambers 13 are formed in the pump section 10. Although a trochoid curve tooth profile is applied to the external teeth 11 a of the inner rotor 11 and the internal teeth 12 a of the outer rotor 12, the present invention is not limited to this, and curve tooth profiles such as an involute curve and a cycloid curve may also be used.

[0011] 1 and 3 , the cover portion 40A is formed with a suction port 42 and a suction port 43 that introduce oil from the outside into the pump chamber 13, and a discharge port 44 and a discharge port 45 that introduce pressure oil (liquid, pressurized liquid) discharged from the pump chamber 13 to the outside. When the drive shaft 1 is rotated by the motor portion 15, the inner rotor 11 and the outer rotor 12 rotate while the external teeth 11 a of the inner rotor 11 slide against the internal teeth 12 a of the outer rotor 12. As the inner rotor 11 and the outer rotor 12 rotate, the volume of the pump chamber 13 repeatedly expands and contracts. In an expansion region (a suction region 65 described later) where the pump chamber 13 expands, oil is sucked in through the suction port 42 and the suction port 43. In a contraction region (a discharge region 66 described later) where the pump chamber 13 contracts, oil is discharged and introduced to the outside through the discharge port 44 and the discharge port 45.

[0012] 1 and 2, the housing 20A has a main body 30A that houses the pump unit 10, and a cover 40A that is attached to the main body 30A and covers the pump unit 10. The main body 30A and the cover 40A are arranged side by side in the axial direction of the drive shaft 1 (hereinafter also simply referred to as the "axial direction").

[0013] As shown in FIG. 2 , the main body 30A has a pump housing recess 31 in which the pump unit 10 is housed. The pump housing recess 31 is a recess with a circular bottom, and the inner rotor 11 and outer rotor 12 of the pump unit 10 are housed eccentrically relative to each other. Specifically, the center of the pump housing recess 31 coincides with the center of the outer rotor 12 and is offset from the center of the drive shaft 1. A plurality of fastening holes 32 are formed in the end surface 30a of the main body 30A, into which fastening members 70 (see FIG. 1) for attaching the cover 40A are fastened. The fastening members 70 are bolts. The fastening holes 32 are formed to correspond to insertion holes 47 (see FIG. 3) provided in the cover 40A.

[0014] 1 and 2, the cover portion 40A is provided to cover the pump accommodation recess 31 that accommodates the inner rotor 11 and the outer rotor 12. The cover portion 40A is attached to the end surface 30a of the main body portion 30A by fastening members 70. The cover portion 40A has a disk-shaped cover main body portion 41 that is attached to the end surface 30a, and a cylindrical protrusion portion 48 that protrudes axially from the cover main body portion 41.

[0015] The cover main body 41 is formed so that an area facing the inner rotor 11 and the outer rotor 12 protrudes in the axial direction. As shown in Figures 1 and 3, the cover main body 41 is formed with the above-mentioned suction port 42, discharge port 44, and suction port 43, a shaft accommodating portion 46 that accommodates the tip end of the drive shaft 1, and a plurality of insertion holes 47 through which fastening members 70 are inserted to fix the cover portion 40A to the main body 30A. The above-mentioned discharge port 45 is also formed in the protruding portion 48.

[0016] As shown in FIG. 3 , the suction port 42 and the discharge port 44 are formed on an arc on the back surface of the cover body 41. The inner peripheries 42a, 44a of the suction port 42 and the discharge port 44 are formed on a circle A1 centered on the drive shaft 1, and the outer peripheries 42b, 44b of the suction port 44 are formed on a circle B1 centered on the outer rotor 12. A discharge-suction transition section 60 is formed between the front end 44c of the discharge port 44 and the rear end 42d of the suction port 42 in the rotational direction of the drive shaft 1, and a suction-discharge transition section 61 is formed between the front end 42c of the suction port 42 and the rear end 44d of the discharge port 44 in the rotational direction of the drive shaft 1. The cover body 41 is divided into multiple imaginary regions by a first imaginary line 62 passing through the midpoint of the discharge-suction transition section 60 and the center of the drive shaft 1, and a second imaginary line 63 perpendicular to the first imaginary line 62 and the drive shaft 1 and passing through the center of the drive shaft 1.

[0017] For example, the suction region 65 is a region (a planar region perpendicular to the axial direction) where the suction port 42 is formed, and is a region on one side (the suction port 42 side) of the first imaginary line 62. The discharge region 66 is a region where the discharge port 44 is formed, and is a region on the other side (the discharge port 44 side) of the first imaginary line 62. The suction port 42 and the discharge port 44 are formed symmetrically with respect to the first imaginary line 62.

[0018] The suction port 43 is formed in an arc on the surface of the cover body 41 and communicates with the suction port 42. The suction port 43 is formed so that its entire surface faces the suction port 42. The shaft accommodating portion 46 is formed in a concave shape at the center of the back surface of the cover body 41. The tip of the drive shaft 1 is accommodated inside the shaft accommodating portion 46, which rotatably supports the drive shaft 1. The discharge port 45 is formed by axially penetrating the protruding portion 48 (see FIG. 1) and communicates with the discharge port 44. The protruding portion 48 (see FIG. 1) of the internal gear pump 100A is inserted into a hole (not shown) provided in the device to which the internal gear pump 100A is attached, and the discharge port 45 is connected to a flow path (not shown). The suction port 43 is connected to a suction passage 80, indicated by a two-dot dashed line, and oil is sucked through the suction passage 80.

[0019] In the discharge region 66, the pump chamber 13 defined by the inner rotor 11 and the outer rotor 12 contracts while pressurizing the oil. As a result, an offset load F (see FIG. 2) acts on the inner rotor 11 and the outer rotor 12 in a direction that moves them away from each other in the discharge region 66. As a result, the clearance between the external gear of the inner rotor 11 and the internal gear of the outer rotor 12 becomes small in the suction region 65, which may deteriorate the sliding characteristics and torque.

[0020] For this reason, the internal gear pump 100A is configured as will be further explained below.

[0021] As shown in FIGS. 2 and 3 , the internal gear pump 100A further includes a first volume chamber R1 provided in the discharge region 66, an inlet passage 49 for introducing oil into the first volume chamber R1, and a discharge passage 50 for discharging oil from the first volume chamber R1. The inlet passage 49 and the discharge passage 50 are both groove-shaped formed on the rear surface of the cover portion 40A and function as passages when the cover portion 40A is attached to the end surface 30a of the main body portion 30A. In FIG. 2 , the suction port 42, the discharge port 44, the inlet passage 49, and the discharge passage 50 formed in the cover portion 40A, as well as the intake passage 80, are indicated by two-dot dash lines. In FIG. 3 , the first volume chamber R1 and the outer periphery of the outer rotor 12 are also indicated by two-dot dash lines. FIG. 4 shows an enlarged view of the first volume chamber R1.

[0022] The inlet passage 49 connects the discharge port 44 to the first volume chamber R1, and pressure oil discharged from the pump section 10 is introduced into the first volume chamber R1 through the inlet passage 49. The discharge passage 50 connects the first volume chamber R1 to the suction port 42, and pressure oil is discharged from the first volume chamber R1 to the suction port 42 through the discharge passage 50. The inlet passage 49 connects to the first volume chamber R1 at one circumferential end, and the discharge passage 50 connects to the first volume chamber R1 at the other circumferential end. Therefore, pressure oil introduced from the discharge port 44 flows through the first volume chamber R1 in a direction from one circumferential end to the other circumferential end, i.e., along the rotational direction of the drive shaft 1. The inlet passage 49 connects to the discharge port 44 at one circumferential end, and the discharge passage 50 connects to the suction port 42 at one circumferential end.

[0023] As shown in FIGS. 2 and 4 , the first volume chamber R1 is defined by the outer periphery of the outer rotor 12, the inner periphery of the pump accommodating recess 31 (recess 33, described later) of the main body 30A, the bottom surface of the pump accommodating recess 31, and the cover 40A. A recess 33 is formed on the inner periphery of the pump accommodating recess 31 where the first volume chamber R1 is formed. The recess 33 is recessed radially from the inner periphery of the pump accommodating recess 31, and its bottom surface 33a extends perpendicular to the radial direction. The recess 33 is axially formed from the end surface 30a of the main body 30A to the bottom surface of the pump accommodating recess 31, matching the thickness of the outer rotor 12. The first volume chamber R1 extends circumferentially, and its circumferential length is set taking into account the biasing force to be applied to the outer rotor 12 based on the pressure oil in the first volume chamber R1. The first volume chamber R1 is formed along the outer periphery and faces the outer periphery of the outer rotor 12. In the first chamber R1, a throttle portion T is formed by the outer periphery of the outer rotor 12 and the bottom surface 33a of the recess 33.

[0024] The throttle portion T is the portion of the first volume chamber R1 with the smallest cross-sectional area (minimum cross-sectional area portion) and its neighboring portion, and is formed along the outer periphery of the outer rotor 12 in the circumferential center of the first volume chamber R1. The cross-sectional area is the cross-sectional area along the radial direction of the first volume chamber R1 between the outer periphery of the outer rotor 12 and the bottom surface 33a of the recess 33. The minimum cross-sectional area portion has a smaller cross-sectional area than the oil inlet side of the first volume chamber R1, and is further smaller than the oil discharge side of the first volume chamber R1. The throttle portion T is formed facing the outer periphery of the outer rotor 12, and a biasing force based on the pressurized oil in the first volume chamber R1, including the throttle portion T, acts on the outer rotor 12.

[0025] In the internal gear pump 100A configured as described above, pressurized oil introduced into the first volume chamber R1 through the introduction passage 49 is drawn into the throttle section T by the rotation of the outer rotor 12, creating a wedge effect that increases the oil pressure above the discharge pressure. Therefore, by biasing the outer rotor 12 against the biased load F with a biasing force based on the oil pressure higher than the discharge pressure, the influence of the biased load F generated in the discharge region 66 can be suitably reduced. Furthermore, the oil that has passed through the throttle section T can be discharged from the first volume chamber R1 through the discharge passage 50.

[0026] The first volume chamber R1 is defined by an outer periphery formed by the circumferential surface of the outer rotor 12 and a bottom surface 33a formed by the flat surface of the recess 33, and the outer periphery of the outer rotor 12 approaches the bottom surface 33a of the recess 33 from the oil inlet side of the first volume chamber R1 toward the throttle section T. Therefore, the first volume chamber R1 has a shape in which the cross-sectional area gradually decreases from the oil inlet side toward the throttle section T. This effectively generates a wedge effect, thereby more suitably reducing the influence of the unbalanced load F. The cross-sectional area of ​​the first volume chamber R1 gradually increases from the throttle section T toward the oil discharge side.

[0027] The pressure oil in the first chamber R1 that has passed through the throttle section T is led to the pump chamber 13 located in the suction region 65 through the discharge passage 50 and the suction port 42. As a result, a drop in oil pressure that may occur in the pump chamber 13 located in the suction region 65 is suppressed, and the occurrence of cavitation is also suppressed.

[0028] A recess of a similar shape may be provided on the bottom surface of the pump accommodating recess 31, facing the suction port 42, and the discharge passage 50 may be formed in the main body 30 and communicate between the first volume chamber R1 and the recess facing the suction port 42. In this manner, too, the pressure oil in the first volume chamber R1 can be guided to the pump chamber 13 located in the suction region 65.

[0029] (First Modification) Next, an internal gear pump 100B according to a first modification will be described with reference to Figures 5 and 6. Figure 5 is a plan view showing the back surface of the cover portion 40B of the housing 20B of the internal gear pump 100B. Figure 6 is a plan view of the pump portion 10 of the internal gear pump 100B and the main body portion 30A of the housing 20B. In Figure 6, the suction port 42, discharge port 44, introduction passage 49, and discharge passage 51 formed in the cover portion 40B, as well as the suction passage 80, are indicated by dashed two-dot lines.

[0030] The first modified example differs from the above embodiment in the configuration of a discharge passage that discharges liquid from the volume chamber. In the first modified example, a discharge passage 51 is formed in the cover portion 40B. As described below, the discharge passage 51 connects to the suction port 42 in a direction S that follows the oil suction flow into the suction port 42, thereby communicating the first volume chamber R1 with the suction port 42. The discharge passage 51 communicates with the suction port 42 at the circumferential center and also communicates with the suction port 42 at a position where the discharge passage 51 axially overlaps with the suction passage 80.

[0031] Oil is sucked into the suction port 42 through the suction passage 80, and the suction flow of oil into the suction port 42 is formed along the extension direction of the suction passage 80. Therefore, the direction S along the suction flow of oil into the suction port 42 is, for example, direction S1 along the extension direction of the suction passage 80 as viewed from the axial direction, and the discharge passage 51 is connected to the suction port 42 in direction S1. This prevents the flow of oil discharged from the discharge passage 51 to the suction port 42 from interfering with the suction flow into the suction port 42, thereby reducing pressure loss.

[0032] The direction S along the intake flow may be a direction S2 or S3 that intersects with the direction S1 at an acute angle α from the exhaust passage 51 toward the intake port 42. The acute angle α can be set to, for example, less than 45 degrees. If the acute angle is less than 45 degrees, the vector component of the direction S1 along the extension direction of the intake passage 80 is larger than the vector component in the direction perpendicular to the direction S1, making it less likely that the intake flow into the intake port 42 will be obstructed. From the perspective of suppressing obstruction of the intake flow into the intake port 42, the smaller the acute angle α, the better.

[0033] The oil sucked into the suction port 42 is subjected to a force in the rotational direction of the drive shaft 1. Between the directions S2 and S3, the direction S2, which forms an acute angle α with respect to the direction S1 in the direction toward the suction port 42, is more aligned with the rotational direction than the direction S3, which forms an acute angle α in the direction away from the suction port 42. Therefore, between the directions S2 and S3, the direction S2 is less likely to obstruct the flow of oil sucked into the suction port 42 and is therefore preferable.

[0034] (Second Modification) Next, an internal gear pump 100C according to a second modification will be described with reference to Fig. 7. Fig. 7 is a plan view showing the pump section 10 of the internal gear pump 100C and the main body section 30B of the housing 20C. In Fig. 7, the suction port 42, the discharge port 44, and the introduction passage 52 formed in the cover section (not shown) of the housing 20C are also shown by dashed two-dot lines.

[0035] The second modified example differs from the above embodiment in the configuration of the volume chamber. In the second modified example, the main body 30B has a second volume chamber R2 facing the outer periphery of the outer rotor 12. The second volume chamber R2 is defined by a recess 34 radially recessed from the pump accommodating recess 31, the outer periphery of the outer rotor 12, and the cover of the internal gear pump 100C, and has a rectangular cross section perpendicular to the radial direction. The cross section is sized to allow a ball 90 (described later) to slide therethrough, and a gap is formed between the second volume chamber R2 and the ball 90. Pressurized oil is introduced into the second volume chamber R2 from the discharge port 44 through an introduction passage 52 that connects the discharge port 44 and the second volume chamber R2. The pressurized oil is introduced near the bottom surface of the second volume chamber R2 (the wall surface 34a of the recess 34 perpendicular to the radial direction).

[0036] The second chamber R2 applies the pressure oil introduced from the discharge port 44 directly to the outer rotor 12. Therefore, the second chamber R2 does not require the discharge passage 50 described in the above embodiment or the discharge passage 51 described in the first modified example. The opening area of ​​the portion of the second chamber R2 facing the outer rotor 12 is set in consideration of the biasing force that should be applied to the outer rotor 12 based on the pressure oil in the second chamber R2, and may be set wider in the circumferential or radial directions than the cross section described above, for example.

[0037] The second chamber R2 accommodates a ball 90 and a spring 91. The ball 90 is provided facing the outer rotor 12, and the spring 91 is provided between the ball 90 and a wall surface 34a that forms the bottom surface of the second chamber R2. The spring 91 is a biasing member that is accommodated in the second chamber R2 in a compressed state and biases the ball 90 toward the outer rotor 12.

[0038] The internal gear pump 100C configured in this manner generates an urging force against the unbalanced load F by the urging force of the spring 91 in addition to the urging force based on the discharge pressure of the pressurized oil introduced into the second chamber R2. Therefore, in this case too, the outer rotor 12 can be urged against the unbalanced load F with an urging force greater than the urging force based on the discharge pressure, thereby suitably reducing the influence of the unbalanced load F. However, if an attempt is made to urge the outer rotor 12 using only the spring 91, it may not be possible to generate a sufficient urging force, or the spring 91 may become too large, resulting in an increase in the size of the internal gear pump 100C or making it difficult to install the spring 91.

[0039] (Other Modifications) Next, other modifications will be described with reference to FIGS. 8 to 10. FIG.

[0040] As shown in Figure 8, the bottom surface 33a of the recess 33 of the first chamber R1 may be, for example, an arcuate surface. In this example, the bottom surface 33a is formed by a gently arcuate surface with a smaller curvature than the cylindrical surface of the outer periphery of the outer rotor 12. Even in this case, a throttle section T can be formed in the circumferential center of the first chamber R1 by the outer periphery of the outer rotor 12 and the arcuate bottom surface 33a, thereby generating a wedge effect. Furthermore, the first chamber R1 can be formed so that the cross-sectional area gradually decreases from the oil inlet side toward the throttle section T, thereby effectively generating a wedge effect.

[0041] 9, the throttle portion T of the first chamber R1 may be, for example, a portion whose cross-sectional area is set to be smaller in a stepped manner compared to the oil inlet side of the first chamber R1. Such a throttle portion T can also generate a wedge effect when oil is drawn in by the rotating outer rotor 12. Alternatively, a wedge effect may be generated by providing multiple steps in the circumferential direction from the oil inlet side to gradually reduce the cross-sectional area.

[0042] 10, the first chamber R1 may be connected to the discharge port 44 through a discharge passage 52 that connects the first chamber R1 to the discharge port 44. Even in this case, the pressure of the pressurized oil in the first chamber R1 is increased above the discharge pressure due to the wedge effect when it is drawn into the throttle section T, so it is possible to discharge the oil from the first chamber R1.

[0043] The configuration, operation, and effects of the embodiment of the present invention will be described below.

[0044] The internal gear pump 100A includes a pump section 10 that discharges oil when a drive shaft 1A is rotated, and a housing 20A that accommodates the pump section 10. The pump section 10 includes an inner rotor 11 that has a plurality of external teeth 11a and is connected to the drive shaft 1A, and an outer rotor 12 that has a plurality of internal teeth 12a that are in sliding contact with the external teeth 11a and is disposed outside the inner rotor 11. The internal gear pump 100A has a throttle section T that faces the outer periphery of the outer rotor 12 in a discharge region 66 and is formed along the outer periphery, a first volume chamber R1 to which pressure oil discharged from the pump section 10 is guided, and a discharge passage 50 that discharges oil that has passed through the throttle section T from the first volume chamber R1.

[0045] According to this configuration, a wedge effect is generated by drawing pressurized oil into the throttle section T by the rotating outer rotor 12, and the oil pressure of the pressurized oil introduced into the first volume chamber R1 can be made higher than the discharge pressure. Therefore, by biasing the outer rotor 12 against the unbalanced load F with a biasing force based on the oil pressure higher than the discharge pressure, the influence of the unbalanced load F generated in the discharge region 66 can be suitably reduced. In addition, the oil that has passed through the throttle section T can be discharged from the first volume chamber R1 via the discharge passage 50.

[0046] The first chamber R1 has a shape in which the cross-sectional area gradually decreases from the oil inlet side toward the throttle portion T.

[0047] According to this configuration, a wedge effect can be effectively generated, and the influence of the unbalanced load F can be reduced more suitably.

[0048] The discharge passage 50 and the discharge passage 51 communicate the first chamber R1 with the pump chamber 13 of the pump section 10 located in the suction region 65 .

[0049] According to this configuration, by guiding the pressurized oil in the first volume chamber R1 through the discharge passage 51 to the pump chamber 13 located in the suction region 65, it is possible to suppress a drop in oil pressure that may occur in the pump chamber 13 located in the suction region 65, thereby suppressing the occurrence of cavitation.

[0050] The discharge passage 51 is connected to the suction port 42 in a direction S along the oil suction flow into the suction port 42 that leads the oil to the pump chamber 13 .

[0051] According to this configuration, the oil in the discharge passage 51 is guided to the suction port 42 so as not to interfere with the suction flow in the suction port 42, thereby suppressing the occurrence of pressure loss.

[0052] The internal gear pump 100C includes a pump section 10 that discharges oil when the drive shaft 1 is rotated, and a housing 20C that accommodates the pump section 10. The pump section 10 includes an inner rotor 11 that has a plurality of external teeth 11a and is connected to the drive shaft 1, and an outer rotor 12 that has a plurality of internal teeth 12a that are in sliding contact with the external teeth 11a and is disposed outside the inner rotor 11. The internal gear pump 100C also includes a second chamber R2 that faces the outer periphery of the outer rotor 12 in the discharge region 66 and to which pressure oil discharged from the pump section 10 is directed, and a spring 91 that is accommodated in the second chamber R2 and biases the outer rotor 12.

[0053] According to this configuration, the outer rotor 12 can be biased against the unbalanced load F by the biasing force of the spring 91 in addition to the biasing force based on the discharge pressure of the pressurized oil introduced into the second chamber R2. Therefore, the influence of the unbalanced load F can be suitably reduced compared to when the outer rotor 12 is biased only by the biasing force based on the discharge pressure.

[0054] Although the embodiments of the present invention have been described above, the above embodiments merely illustrate some of the application examples of the present invention, and it is not intended that the technical scope of the present invention be limited to the specific configurations of the above embodiments.

[0055] This application claims priority based on Japanese Patent Application No. 2023-098722, filed with the Japan Patent Office on June 15, 2023, the entire contents of which are incorporated herein by reference.

Claims

1. The pump section discharges liquid as the drive shaft rotates, The system comprises a housing that accommodates the pump section, The pump section comprises an inner rotor having a plurality of external teeth and connected to the drive shaft, and an outer rotor having a plurality of internal teeth that slide in contact with the external teeth and positioned outside the inner rotor. The discharge region has a constricted portion facing the outer circumference of the outer rotor and formed along the outer circumference, and a volume chamber through which the liquid discharged from the pump section is guided, It has a discharge passage for discharging the liquid that has passed through the restricting portion from the volume chamber, In the discharge region, the outer rotor is biased toward the inner rotor. Internal gear pump.

2. An internal gear pump according to claim 1, The volume chamber has a shape in which the cross-sectional area gradually decreases from the liquid introduction side toward the constricted portion. Internal gear pump.

3. An internal gear pump according to claim 1, The aforementioned discharge passage connects the volume chamber and the pump chamber of the pump section located in the suction region. Internal gear pump.

4. An internal gear pump according to claim 3, The discharge passage is connected to the suction port in a direction that aligns with the suction flow of liquid to the suction port that leads the liquid to the pump chamber. Internal gear pump.

5. The pump section discharges liquid as the drive shaft rotates, The system comprises a housing that accommodates the pump section, The pump section comprises an inner rotor having a plurality of external teeth and connected to the drive shaft, and an outer rotor having a plurality of internal teeth that slide in contact with the external teeth and positioned outside the inner rotor. In the discharge region, a volume chamber facing the outer circumference of the outer rotor, through which the liquid discharged from the pump section is guided, The volume chamber contains a biasing member that biases the outer rotor toward the inner rotor in the discharge region, Internal gear pump.