WO2024257563A1 - Internal gear pump - Google Patents

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

The present invention relates to an internal gear pump.

JP 6096545B discloses an oil pump with an oil guide groove formed in 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, which communicates 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 to introduce pump discharge pressure over a specified angular range. JP 7-145785A discloses a trochoidal type 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.

In the discharge region of an internal gear pump, the pump chamber defined by the inner rotor and outer rotor shrinks while pressurizing the liquid. As a result, an unbalanced load acts on the inner rotor and 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 smaller, which can lead to poor sliding characteristics and torque deterioration.

The present invention was made in consideration of these problems, and aims to effectively reduce the effects of unbalanced loads that occur in the discharge area.

According to one aspect of the present invention, there is provided an internal gear pump comprising a pump section which discharges liquid by rotating a drive shaft, and a housing which accommodates the pump section, the pump section having an inner rotor having a number of external teeth and connected to the drive shaft, and an outer rotor having a number of internal teeth which are in sliding contact with the external teeth and which is disposed outside the inner rotor, the pump section having a throttle section which faces the outer periphery of the outer rotor in the discharge region and is formed along said outer periphery, a volume chamber into which the liquid discharged from the pump section is guided, and a discharge passage which discharges the liquid which has passed through the throttle section from the volume chamber.

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

Below, 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 an 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 is used as a viscous fluid as the liquid discharged by the internal gear pump, but instead of oil, for example, a water-soluble substitute liquid may be used.

The 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 with the cover section 40A removed (plan view of the pump section 10 and the main body section 30A of the housing 20A). Figure 3 is a plan view showing the back surface of the cover section 40A that covers the pump section 10.

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

As shown in FIG. 2, the pump section 10 has 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 the outer rotor 12 are housed in a housing 20A (specifically, a main body section 30A described later), are arranged eccentrically with respect to each other, and are covered by a cover section 40A of the housing 20A. Specifically, the inner rotor 11 is arranged so that its center coincides with the center of the drive shaft 1, and the outer rotor 12 is arranged so that its center is shifted downward from the drive shaft 1 in FIGS. 1 and 2. The inner rotor 11 has a plurality of external teeth 11a on its outer peripheral surface, and the outer rotor 12 has a plurality of internal teeth 12a on its inner peripheral surface that are in sliding contact with the external teeth 11a. The external teeth 11a and the internal teeth 12a are formed with different numbers of teeth, and a pump chamber 13 is defined by the adjacent external teeth 11a of the inner rotor 11 and the internal teeth 12a of the outer rotor 12. A plurality of pump chambers 13 are formed in the pump section 10. Note that a trochoid curve tooth profile is applied to the external teeth 11a of the inner rotor 11 and the internal teeth 12a of the outer rotor 12, but this is not limited thereto, and curve tooth profiles such as an involute curve or a cycloid curve may also be used.

As shown in Figs. 1 and 3, the cover section 40A is formed with a suction port 42 and a suction port 43 for leading oil from the outside to the pump chamber 13, and a discharge port 44 and a discharge port 45 for leading the pressurized oil (liquid, pressurized liquid) discharged from the pump chamber 13 to the outside. When the drive shaft 1 is rotated by the motor section 15, the inner rotor 11 and the outer rotor 12 rotate while the outer teeth 11a of the inner rotor 11 slide against the inner teeth 12a 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 the expansion region (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, and in the contraction region (discharge region 66 described later) where the pump chamber 13 contracts, oil is discharged and led to the outside through the discharge port 44 and the discharge port 45.

As shown in Figures 1 and 2, the housing 20A has a main body 30A that houses the pump section 10, and a cover 40A that is attached to the main body 30A and covers the pump section 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").

As shown in FIG. 2, the main body 30A has a pump accommodating recess 31 in which the pump section 10 is accommodated. The pump accommodating recess 31 is a recess with a circular bottom surface, and the inner rotor 11 and outer rotor 12 of the pump section 10 are accommodated eccentrically relative to each other inside. Specifically, the center of the pump accommodating recess 31 coincides with the center of the outer rotor 12 and is formed 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 section 40A are fastened. The fastening members 70 are bolts. The fastening holes 32 are formed to correspond to the insertion holes 47 (see FIG. 3) provided in the cover section 40A.

As shown in Figures 1 and 2, the cover part 40A is provided to cover the pump accommodation recess 31 in which the inner rotor 11 and the outer rotor 12 are accommodated. The cover part 40A is attached to the end surface 30a of the main body part 30A by a fastening member 70. The cover part 40A has a disk-shaped cover main body part 41 attached to the end surface 30a, and a cylindrical protrusion part 48 formed to protrude in the axial direction from the cover main body part 41.

The cover body 41 is formed with an area that faces the inner rotor 11 and the outer rotor 12 protruding in the axial direction. As shown in Figures 1 and 3, the cover 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 of the drive shaft 1, and a number of insertion holes 47 through which fastening members 70 are inserted to fix the cover portion 40A to the body portion 30A. The above-mentioned discharge port 45 is also formed in the protruding portion 48.

3, the suction port 42 and the discharge port 44 are formed on a circular arc on the back surface of the cover body 41. The inner circumferences 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 circumferences 42b, 44b of the suction port 42 and the discharge port 44 are formed on a circle B1 centered on the outer rotor 12. A discharge-suction transition section 60 is formed between the tip end 44c of the discharge port 44 and the rear end 42d of the suction port 42 in the rotation direction of the drive shaft 1, and a suction-discharge transition section 61 is formed between the tip end 42c of the suction port 42 and the rear end 44d of the discharge port 44 in the rotation direction of the drive shaft 1. The cover body 41 is divided into a plurality of virtual regions by a first virtual line 62 passing through the midpoint of the discharge-suction transition section 60 and the center of the drive shaft 1, and a second virtual line 63 perpendicular to the first virtual line 62 and the drive shaft 1 and passing through the center of the drive shaft 1.

For example, the suction area 65 is the area where the suction port 42 is formed (planar area perpendicular to the axial direction) and is the area on one side (the suction port 42 side) of the first imaginary line 62. The discharge area 66 is the area where the discharge port 44 is formed and is the area 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.

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 the entire suction port 43 faces the suction port 42. The shaft accommodating portion 46 is formed in a concave shape in 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, and the shaft accommodating portion 46 supports the drive shaft 1 so that it can rotate freely. The discharge port 45 is formed by penetrating the protruding portion 48 in the axial direction (see FIG. 1) and communicates with the discharge port 44. The internal gear pump 100A has the protruding portion 48 (see FIG. 1) 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 the suction passage 80 shown by the two-dot dashed line, and oil is sucked through the suction passage 80.

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 smaller in the suction region 65, which can deteriorate the sliding characteristics and torque.

For this reason, the internal gear pump 100A is further configured as described below.

2 and 3, the internal gear pump 100A further includes a first volume chamber R1 provided in the discharge area 66, an introduction 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. Both the introduction passage 49 and the discharge passage 50 are formed in a groove shape on the back surface of the cover part 40A, and are configured as passages when the cover part 40A is installed on the end surface 30a of the main body part 30A. In addition, in FIG. 2, the suction port 42, the discharge port 44, the introduction passage 49, and the discharge passage 50 formed in the cover part 40A, as well as the suction passage 80, are shown by two-dot dashed lines. In addition, in FIG. 3, the first volume chamber R1 and the outer periphery of the outer rotor 12 are also shown by two-dot dashed lines. In FIG. 4, the first volume chamber R1 is shown in an enlarged state.

The inlet passage 49 connects the discharge port 44 to the first volume chamber R1, and pressure oil discharged from the pump unit 10 is introduced to 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, in the first volume chamber R1, pressure oil introduced from the discharge port 44 flows in the direction from one circumferential end to the other end, that is, along the rotation 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.

2 and 4, the first volume chamber R1 is defined by the outer periphery of the outer rotor 12 and the inner periphery of the pump accommodating recess 31 of the main body 30A (recess 33 described later), and is also defined by 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 formed in a concave shape along the radial direction from the inner circumferential surface of the pump accommodating recess 31, and its bottom surface 33a is provided along a direction perpendicular to the radial direction. The recess 33 is provided in the axial direction from the end surface 30a of the main body 30A to the bottom surface of the pump accommodating recess 31 in accordance with the thickness of the outer rotor 12. The first volume chamber R1 extends along the circumferential direction, and its circumferential length is set in consideration of the biasing force to be applied to the outer rotor 12 based on the pressure oil in the first volume chamber R1. The first 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.

The throttling 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 in the portion sandwiched 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 throttling 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 throttling portion T, acts on the outer rotor 12.

In the internal gear pump 100A configured in this manner, the pressurized oil introduced into the first volume chamber R1 through the inlet passage 49 is drawn into the throttling section T by the rotation of the outer rotor 12, creating a wedge effect, which 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 effects of the biased load F generated in the discharge area 66 can be suitably reduced. In addition, the oil that has passed through the throttling section T can be discharged from the first volume chamber R1 through the discharge passage 50.

The first volume chamber R1 is defined by an outer periphery consisting of the circumferential surface of the outer rotor 12 and a bottom surface 33a consisting of 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 throttling 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 throttling section T. This effectively generates a wedge effect, so that the influence of the unbalanced load F can be more suitably reduced. The first volume chamber R1 has a shape in which the cross-sectional area gradually increases from the throttling section T toward the oil discharge side.

The pressurized oil in the first volumetric chamber R1 that has passed through the throttling 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, the 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.

The bottom surface of the pump accommodating recess 31 may be provided with a recess of a similar shape 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 way, the pressurized oil in the first volume chamber R1 can be guided to the pump chamber 13 located in the suction region 65.

(First Modification)
Next, an internal gear pump 100B according to a first modified example 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, the discharge port 44, the introduction passage 49, and the discharge passage 51 formed in the cover portion 40B are shown together with the suction passage 80 by two-dot dashed lines.

The first modified example differs from the above embodiment in the configuration of the 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, and the discharge passage 51 connects to the suction port 42 in a direction S that follows the suction flow of oil into the suction port 42, as described below, 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 it axially overlaps with the suction passage 80.

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. For this reason, 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 connects 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.

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

The oil sucked into the suction port 42 is subjected to a force in the rotational direction of the drive shaft 1. Between orientations S2 and S3, orientation S2, which forms an acute angle α with respect to orientation S1 in the direction toward the suction port 42, is more in line with the rotational direction than orientation S3, which forms an acute angle α in the direction away from the suction port 42. For this reason, between orientations S2 and S3, orientation S2 is less likely to impede the flow of oil sucked into the suction port 42, and is therefore preferable.

(Second Modification)
Next, an internal gear pump 100C according to a second modified example 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 two-dot dashed lines.

The second modified embodiment differs from the above embodiment in the configuration of the volume chamber. In the second modified embodiment, 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 formed in a radially concave shape from the pump accommodating recess 31, the outer periphery of the outer rotor 12, and the cover part of the internal gear pump 100C, and has a rectangular cross section perpendicular to the radial direction. The cross section is set to a size that allows the ball 90 described later to slide, and a gap is formed between the second volume chamber R2 and the ball 90 by the cross section. Pressurized oil is introduced into the second volume chamber R2 from the discharge port 44 through an introduction passage 52 that communicates between 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 (wall surface 34a perpendicular to the radial direction of the recess 34).

The second chamber R2 applies the pressurized 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 taking into consideration the biasing force to be applied to the outer rotor 12 based on the pressurized 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.

The second chamber R2 contains a ball 90 and a spring 91. The ball 90 faces the outer rotor 12, and the spring 91 is provided between the ball 90 and the wall surface 34a that constitutes the bottom surface of the second chamber R2. The spring 91 is a biasing member that is contained in the second chamber R2 in a compressed state and biases the ball 90 toward the outer rotor 12.

The internal gear pump 100C configured in this manner generates a biasing force against the biased 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 volume chamber R2. Therefore, in this case too, the outer rotor 12 can be biased against the biased load F with a biasing force greater than the biasing force based on the discharge pressure, so the influence of the biased load F can be suitably reduced. Note that if an attempt is made to bias the outer rotor 12 only by the spring 91, it may not be possible to generate a suitable biasing 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.

(Other Modifications)
Next, other modified examples will be described with reference to FIGS.

As shown in FIG. 8, the bottom surface 33a of the recess 33 of the first chamber R1 may be, for example, an arc surface. In this example, the bottom surface 33a is formed by a gentle arc 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 arc-shaped bottom surface 33a, so a wedge effect can be generated. In addition, the first chamber R1 can be formed in a shape in which the cross-sectional area gradually decreases from the oil inlet side toward the throttle section T, so a wedge effect can also be effectively generated.

As shown in FIG. 9, the throttling portion T of the first chamber R1 may be, for example, a portion in which the cross-sectional area is set to be smaller in a stepped manner than the oil inlet side of the first chamber R1. Even with such a throttling portion T, a wedge effect can be generated when oil is drawn in by the rotating outer rotor 12. Alternatively, a wedge effect can be generated by providing multiple steps in the circumferential direction from the oil inlet side to gradually reduce the cross-sectional area.

As shown in FIG. 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 oil in the first chamber R1 is increased above the discharge pressure due to the wedge effect when it is drawn into the throttling section T, so it is possible to discharge the oil from the first chamber R1.

The configuration, operation, and effects of the embodiment of the present invention are summarized below.

The internal gear pump 100A includes a pump section 10 that discharges oil when the 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 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 100A has a throttle section T that faces the outer periphery of the outer rotor 12 in the 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.

With this configuration, the rotating outer rotor 12 draws pressurized oil into the throttling section T, creating a wedge effect and making the oil pressure of the pressurized oil introduced into the first chamber R1 higher than 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 effects of the biased load F generated in the discharge area 66 can be suitably reduced. In addition, the oil that has passed through the throttling section T can be discharged from the first chamber R1 via the discharge passage 50.

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

This configuration effectively creates a wedge effect, so the effects of the unbalanced load F can be more effectively reduced.

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

With this configuration, the pressurized oil in the first volumetric chamber R1 is guided through the discharge passage 51 to the pump chamber 13 located in the suction region 65, thereby suppressing the drop in oil pressure that may occur in the pump chamber 13 located in the suction region 65, thereby suppressing the occurrence of cavitation.

The discharge passage 51 connects to the suction port 42 in a direction S that is in line with the oil suction flow into the suction port 42, which guides the oil to the pump chamber 13.

With this configuration, the oil in the discharge passage 51 is guided to the suction port 42 without interfering with the suction flow in the suction port 42, thereby suppressing the occurrence of pressure loss.

The internal gear pump 100C comprises 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 comprises 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 that are in sliding contact with the external teeth 11a and disposed outside the inner rotor 11. The internal gear pump 100C comprises a second volume chamber R2 that faces the outer periphery of the outer rotor 12 in the discharge region 66 and to which the pressurized oil discharged from the pump section 10 is guided, and a spring 91 that is accommodated in the second volume chamber R2 and biases the outer rotor 12.

With this configuration, the outer rotor 12 can be biased against the biased 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 guided to the second volume chamber R2. Therefore, the effect of the biased 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.

　Although the embodiments of the present invention have been described above, the above embodiments merely show some of the application examples of the present invention, and are not intended to limit the technical scope of the present invention to the specific configurations of the above embodiments.

This application claims priority to 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 (5)

a pump unit that discharges liquid by rotating a drive shaft;
A housing that accommodates the pump portion,
the pump section includes 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 disposed outside the inner rotor,
a volume chamber having a throttle portion formed along an outer periphery of the outer rotor in a discharge region, the volume chamber receiving the liquid discharged from the pump portion;
A discharge passage for discharging the liquid that has passed through the throttle portion from the volume chamber.
Internal gear pump. 2. The internal gear pump according to claim 1,
The volume chamber has a shape in which the cross-sectional area gradually decreases from the liquid inlet side toward the throttle portion.
Internal gear pump. 2. The internal gear pump according to claim 1,
The discharge passage communicates the volume chamber with a pump chamber of the pump section located in the suction region.
Internal gear pump. The internal gear pump according to claim 3,
the discharge passage is connected to the suction port in a direction parallel to the intake flow of liquid into the suction port which directs liquid into the pump chamber;
Internal gear pump. a pump unit that discharges liquid by rotating a drive shaft;
A housing that accommodates the pump portion,
the pump section includes 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 disposed outside the inner rotor,
a volume chamber facing an outer periphery of the outer rotor in a discharge region, into which liquid discharged from the pump portion is guided;
a biasing member that is accommodated in the volume chamber and biases the outer rotor,
Internal gear pump.

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