阅读说明：本技术 泵装置 (Pump device ) 是由 海野圭祐 于 2020-02-28 设计创作，主要内容包括：一种泵装置包括旋转体、包括有吸入端口(83)和排出端口(84)的泵外壳(2),和卸压阀(9)。在该泵装置中,通过旋转体的旋转,流体被从吸入端口(83)吸入并且被从排出端口(84)排出。卸压阀(9)包括阀体(91)和偏压构件。排出端口(84)包括在排出端口(84)延伸的方向上的一端部。该一端部比排出端口(84)的中央部浅。泵外壳包括卸压流路,当卸压阀(9)打开时流体流过该卸压流路。卸压流路被设置成朝向排出端口(84)的该一端部的沟槽底表面打开。(A pump device includes a rotary body, a pump housing (2) including a suction port (83) and a discharge port (84), and a pressure relief valve (9). In the pump device, fluid is sucked from a suction port (83) and discharged from a discharge port (84) by rotation of the rotary body. The pressure relief valve (9) includes a valve body (91) and a biasing member. The discharge port (84) includes one end portion in a direction in which the discharge port (84) extends. The one end portion is shallower than a central portion of the discharge port (84). The pump housing includes a pressure relief flow path through which fluid flows when the pressure relief valve (9) is opened. The pressure relief flow path is provided so as to open toward the groove bottom surface of the one end portion of the discharge port (84).)

1. A pump device (1), characterized by comprising:

a rotary body rotationally driven around a rotation axis;

a pump housing (2) that includes a suction port (83) and a discharge port (84), the suction port (83) and the discharge port (84) opening toward a housing chamber (20) that houses the rotating body, the suction port (83) and the discharge port (84) extending in the shape of an arc-shaped groove; and

a pressure relief valve (9) that opens when the hydraulic pressure in the discharge port (84) becomes equal to or higher than a predetermined value, wherein:

in the pump device (1), by the rotation of the rotary body, fluid is sucked from the suction port (83) and discharged from the discharge port (84);

the pressure relief valve (9) includes a valve body (91) and a biasing member that biases the valve body (91) in a valve closing direction;

the discharge port (84) includes one end portion in a direction in which the discharge port (84) extends, the one end portion being shallower than a central portion of the discharge port (84);

the pump housing (2) includes a pressure relief flow path (87) through which the fluid flows when the pressure relief valve (9) is opened, the pressure relief flow path (87) being provided so as to open toward a groove bottom surface of the one end portion of the discharge port (84); and is

A valve body (91) and a biasing member of the pressure relief valve (9) are arranged in a direction parallel to the rotation axis with an opening (87b) of the pressure relief flow path (87), the opening (87b) being provided in the groove bottom surface.

2. The pump device (1) according to claim 1, characterized in that the rotating body defines a plurality of pump chambers (30) on an outer peripheral side of the rotating body, each of the pump chambers (30) has a volume that changes with rotation of the rotating body, the pump device performs a pump operation in which the fluid flows from the suction port (83) into each of the pump chambers (30) in a suction stroke in which the volume increases, and the fluid flows from each of the pump chambers (30) into the discharge port (84) in a discharge stroke in which the volume decreases, and the one end of the discharge port (84) is one of two ends of the discharge port (84) in the direction in which the discharge port (84) extends, and each of the pump chambers (30) communicates with the end portion in an initial stage of the discharge stroke.

3. The pump device (1) according to claim 1 or 2, characterized in that a groove bottom surface of the discharge port (84) is an inclined surface that causes a depth of the discharge port (84) in a direction parallel to the rotation axis to gradually increase from the one end portion toward the central portion.

4. A pump device (1) according to claim 1 or 2, wherein said biasing member is a coil spring (92) and the direction in which said coil spring (92) extends and contracts is substantially parallel to said axis of rotation.

5. The pump device (1) according to claim 1 or 2, characterized in that the pump housing (2) includes a disk-shaped body portion including the suction port (83) and the discharge port (84), a tubular portion is provided in the body portion, the tubular portion includes the pressure relief flow path (87) inside the tubular portion, the tubular portion accommodates the valve body (91) and the biasing member, and the tubular portion is located entirely radially inside an outer peripheral surface of the body portion when the pump housing (2) is viewed in the direction of the rotation axis.

6. The pump device (1) according to claim 4, characterized by further comprising an electric motor unit that rotationally drives the rotary body, wherein the rotary body is attached to an output rotary shaft of the electric motor unit, the coil spring (92) is housed in a tubular portion provided in the pump housing (2), and the tubular portion is located entirely radially inside an outer peripheral surface of the electric motor unit when the pump housing (2) is viewed in the direction of the rotary axis.

Technical Field

The present invention relates to a pump device.

Background

Conventionally, an electric pump device is widely used which is attached to, for example, a transmission case of a vehicle and sucks transmission oil from an oil pan to supply the oil to each part for lubrication, cooling, and the like. In such a pump device, the rotor is rotated in the housing chamber of the housing by an electric motor as a drive source. The housing includes a suction port and a discharge port that open toward the accommodation chamber. When the rotor rotates in the accommodation chamber, oil sucked from the suction port is discharged from the discharge port. The pump devices described in japanese unexamined patent application publication No. 2008-.

In the pump device (electric oil pump) described in JP 2008-215087A, a fluid communication hole through which the discharge side and the suction side of the pump communicate with each other is provided in a valve body as a valve body. This spool is biased in the valve closing direction by a coil spring. When the discharge pressure becomes high, the spool is retracted against the biasing force of the coil spring to allow the discharge side and the suction side of the pump to communicate with each other through the fluid communication hole. The coil spring is disposed in a compressed state between the valve spool and the adjustment screw, and a central axis of the coil spring extends in a direction perpendicular to a rotational axis of the electric motor. The spool advances and retracts along the central axis of the coil spring according to the discharge pressure.

The pump device (electric pump) described in JP 2013-241837A includes a pressure receiving body as a valve body at a position facing the discharge port via a flow path, and the pressure receiving body is biased toward the discharge port in the valve closing direction by a coil spring. The pump device comprises an opening on the downstream side of the pressure receiving body. When the pressure receiving body is retracted by a predetermined amount, the opening is opened. When the pressure receiving body is retracted due to the pressure received from the discharge port and the opening is opened, a part of the fluid in the discharge port is discharged from the opening to the outside. The coil spring is accommodated in the tubular portion of the housing such that a central axis of the coil spring extends parallel to the rotational axis of the electric motor. The coil spring is axially compressed between a plug body closing one end of the tubular portion and the pressure receiving body.

Disclosure of Invention

For example, as in the pump device described in JP 2008-215087A, when the center axis of the coil spring is perpendicular to the rotation axis of the electric motor, the pump device attached to the circular opening of the transmission housing may not be attachable to the transmission housing. This is because the coil spring or the adjustment screw protrudes outward in the radial direction of the pump housing. When the coil spring is disposed such that its central axis extends parallel to the rotational axis of the electric motor as in JP 2013-241837A, the housing can be inserted into the transmission case through the opening of the transmission case without increasing the opening diameter of the opening of the transmission case. However, because the tubular portion of the housing that accommodates the coil spring protrudes to a large extent in the axial direction parallel to the rotational axis of the electric motor, the tubular portion tends to interfere with the constituent members in the transmission housing.

The invention provides a pump device capable of realizing size reduction.

A pump apparatus according to a first aspect of the present invention includes: a rotary body rotationally driven around a rotation axis; a pump housing including a suction port and a discharge port that open toward a housing chamber in which the rotary body is housed, the suction port and the discharge port extending in the shape of an arc-shaped groove; and a pressure relief valve that opens when the hydraulic pressure in the discharge port becomes equal to or higher than a predetermined value. In the pump device, fluid is sucked from the suction port and discharged from the discharge port by rotation of the rotary body. The pressure relief valve includes a valve body and a biasing member that biases the valve body in a valve closing direction. The discharge port includes one end portion in a direction in which the discharge port extends, and the one end portion is shallower than a central portion of the discharge port. The pump housing includes a pressure relief flow path through which fluid flows when the pressure relief valve opens. The relief flow path is provided so as to open to the groove bottom surface of the one end portion of the discharge port. The valve body and the biasing member of the pressure relief valve are arranged in a direction parallel to the rotational axis with the opening of the pressure relief flow path. An opening is disposed in the trench bottom surface.

The present invention achieves a reduction in the size of the pump apparatus.

Drawings

Features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will be described below with reference to the accompanying drawings, in which like numerals represent like elements, and in which:

fig. 1A is a sectional view showing a configuration example of a pump device attached to an opening of a transmission case, which is an object to which the pump device is to be attached, and fig. 1B and 1C are partially enlarged sectional views of the pump device;

FIG. 2 is a cross-sectional view of the pump apparatus taken along line II-II in FIG. 1A;

fig. 3A and 3B are perspective views of a second housing member, wherein fig. 3A illustrates a surface of the second housing member opposite to the first housing member, and fig. 3B illustrates a surface of the second housing member facing the first housing member;

fig. 4A illustrates the second housing member as viewed in the axial direction from the opposite side of the second housing member from the first housing member, and fig. 4B illustrates the second housing member as viewed in the axial direction from the first housing side of the second housing member;

FIG. 5 is a cross-sectional view of the second housing member and the pressure relief valve taken along line V-V in FIG. 4B; and is

Fig. 6 is a graph showing the measurement result of the relationship between the oil flow rate and the oil pressure measured in one end portion and the other end portion of the discharge port.

Detailed Description

An embodiment of the present invention will be described with reference to fig. 1A to 6. The embodiments described below are shown as specific examples suitable for implementing the present invention, and in some parts, specifically illustrate various technical problems that are technically preferable. The technical scope of the present invention is not limited to this specific embodiment.

Fig. 1A is a sectional view illustrating a configuration example of a pump device 1 of an opening 100 of a transmission case 10, which is an object to which the pump device 1 is to be attached. Fig. 1B and 1C are partially enlarged sectional views of the pump device 1. Fig. 2 is a sectional view of the pump device 1 taken along line II-II in fig. 1A. In FIG. 1A, the transmission housing 10 is shown in hidden outline (a long double short dashed line). The pump device 1 is attached to the gearbox housing 10, wherein a part of the pump device 1 is inserted in a circular opening 100 of the gearbox housing 10. In fig. 1A to 1C, the lower side of the drawing corresponds to the inside of the transmission case 10.

In the present embodiment, the pump device 1 is configured as an electric pump including an electric motor unit (described later) as a drive source. The pump apparatus 1 is mounted on an electric vehicle or a hybrid vehicle including a high-power motor such as an interior permanent magnet motor (IPM) as a driving source for moving the vehicle. The pump device 1 sucks oil (transmission oil) as a fluid of the present invention from an oil pan of the transmission case 10 and supplies the oil to an object to which the oil is to be supplied. Examples of the object to which oil is to be supplied include a high-power motor and a transmission mechanism of a transmission. The oil supplied from the pump device 1 is used to lubricate, cool, or operate an object to which the oil is to be supplied and is returned from the object to the oil pan.

The pump device 1 includes a pump housing 2, a pump unit 3, an electric motor unit 4, and a control unit 5. The pump housing 2 includes a housing chamber 20. The pump unit 3 includes an inner rotor 31 and an outer rotor 32 accommodated in the accommodation chamber 20 of the pump housing 2. The electric motor unit 4 rotationally drives the inner rotor 31. The control unit 5 controls the electric motor unit 4.

The electric motor unit 4 includes a stator core 41, a rotor core 42, a rotor shaft 43, and a motor housing 44. The stator core 41 is made of a soft magnetic metal and includes a plurality of teeth. The rotor core 42 is disposed inside the stator core 41. The rotor shaft 43 is an output rotation shaft and is inserted through the center of the rotor core 42. The motor housing 44 is made of resin for molding the stator core 41. A plurality of permanent magnets 421 are fixed to the rotor core 42. The coil 412 is wound around the stator core 41 with the insulator 411 interposed therebetween. A three-phase Alternating Current (AC) motor current is supplied from the control unit 5 to the coil 412. The stator core 41 generates a rotating magnetic field by a motor current supplied to the coil 412. The rotor core 42 rotates to follow this rotating magnetic field.

The rotor shaft 43 is rotatably supported by a bearing (not shown) attached to the pump housing 2, and rotates with the rotor core 42. The pump device 1 is attached to the gearbox housing 10 with bolts, not shown. For example, the pump device 1 is attached in a direction such that the rotor shaft 43 extends horizontally.

The control unit 5 is constituted by a circuit board 51 and a plurality of electronic components mounted on the circuit board 51. The control unit 5 operates using the DC voltage supplied to the terminal 50 of the connector unit 441 provided in the motor housing 44 as its power supply. The circuit board 51 is covered by a metal cover 500 attached to the motor housing 44. The plurality of electronic components includes a Central Processing Unit (CPU) and a switching element. The control unit 5 generates a motor current to be supplied to the electric motor unit 4 by Pulse Width Modulation (PWM) control achieved by opening and closing the switching element. In the present embodiment, the control unit 5 is integrated with the electric motor unit 4. However, the control unit 5 may be separated from the electric motor unit 4 and connected to the electric motor unit 4 by a cable.

As shown in fig. 2, the pump unit 3 includes a circular plate-shaped inner rotor 31 including a plurality of outer teeth 311 and an annular outer rotor 32 including a plurality of inner teeth 321. The inner rotor 31 is a rotary body rotationally driven by the electric motor unit 4. The inner rotor 31 is attached to the rotor shaft 43 so as not to be rotatable relative to the rotor shaft 43. In the present embodiment, the rotor shaft 43 is spline-fitted in the center of the inner rotor 31. In fig. 1A, the rotation axis O of the rotor shaft 43 is shown by a long and short dashed line. The inner rotor 31 is rotationally driven about the rotation axis O by the electric motor unit 4. Hereinafter, a direction parallel to the rotation axis O is sometimes referred to as an axial direction.

The number of the inner teeth 321 of the outer rotor 32 is one more than the number of the outer teeth 311 of the inner rotor 31. The outer rotor 32 is provided in the accommodation chamber 20 so as to be rotatable about a position eccentric from the rotation center of the inner rotor 31. The inner rotor 31 defines a plurality of pump chambers 30 between the inner rotor 31 and the outer rotor 32, and the outer rotor 32 is disposed on an outer peripheral side of the inner rotor 31. The plurality of pump chambers 30 are defined by the external teeth 311 of the inner rotor 31 and the internal teeth 321 of the outer rotor 32. The volume of each pump chamber 30 changes as the inner rotor 31 and the outer rotor 32 rotate.

In the present embodiment, the pump unit 3 is configured as an internal gear pump. However, the present invention is not limited thereto, and the pump unit 3 may be configured as, for example, a vane pump. In this case, the rotor, which is a rotating body having radial slits that accommodate a plurality of blades, is rotationally driven by the electric motor unit 4. A plurality of pump chambers are defined on an outer peripheral side of the rotor by vanes, and a volume of each pump chamber changes with rotation of the rotor.

The pump housing 2 includes a first housing member 7 and a second housing member 8 and is fixed to the motor housing 44 by a plurality of bolts 66. When the pump device 1 is attached to the transmission case 10, the entire pump housing 2 is disposed in the transmission case 10. In the present embodiment, the pump housing 2 is fixed to the motor housing 44 by three bolts 66, and one of the bolts 66 is shown in fig. 1A. Each bolt 66 is screwed into a nut member 67 molded in the motor housing 44.

The first housing member 7 is made of die cast metal. The first housing member 7 is a one-piece member, which is constituted by a disk-shaped body portion 71 including the housing chamber 20 in the center, and a plurality of projections 72 projecting radially outward from an outer peripheral surface 71a of the body portion 71. In the present embodiment, the first housing member 7 includes three protruding portions 72 protruding in the radial direction, and each protruding portion 72 includes a bolt insertion hole 720 through which the bolt 66 is inserted. The first housing member 7 is disposed between the second housing member 8 and the motor housing 44, and a part of the first housing member 7 in the axial direction is fitted in the motor housing 44.

The first housing member 7 includes an insertion hole 70 in the center. The rotor shaft 43 is inserted through the insertion hole 70, and the tip end of the rotor shaft 43 is disposed in the central hole 80 of the second housing member 8. The first housing member 7 holds the annular seal member 69, and the seal member 69 is in elastic contact with the rotor shaft 43.

Fig. 3A and 3B are perspective views of the second housing member 8. Fig. 3A illustrates a surface of the second housing member 8 opposite to the first housing member 7, and fig. 3B illustrates a surface of the second housing member 8 facing the first housing member 7. Fig. 4A illustrates the second housing member 8 when viewed in the axial direction from the opposite side of the second housing member 8 from the first housing member 7, and fig. 4B illustrates the second housing member 8 when viewed in the axial direction from the first housing member 7 side of the second housing member 8. Fig. 1A shows a cross section taken along line I-I in fig. 4B.

The second housing member 8 is made of die-cast metal similarly to the first housing member 7. The second housing member 8 is a one-piece member, and is constituted by a disk-shaped body portion 81, the body portion 81 having the same diameter as the body portion 71 of the first housing member 7, and a plurality of projecting portions 82, the plurality of projecting portions 82 projecting radially outward from an outer peripheral surface 81a of the body portion 81. In the present embodiment, the second housing member 8 includes three protruding portions 82 protruding in the radial direction, similarly to the first housing member 7, and each protruding portion 82 includes a bolt insertion hole 820 through which the bolt 66 is inserted. The metal material for the first and second case members 7 and 8 is suitably an aluminum alloy. However, the present invention is not limited thereto, and the metal material may be, for example, an iron-based metal.

The body portion 71 of the first housing member 7 and the body portion 81 of the second housing member 8 are positioned relative to each other in the radial direction and the circumferential direction by two positioning pins 60 (see fig. 2). The body portion 71 of the first housing member 7 includes fitting holes 710 at two positions with the housing chamber 20 interposed therebetween, and the two positioning pins 60 are fitted in the fitting holes 710. Similarly, the body portion 81 of the second housing member 8 includes fitting holes 810 at two positions, and the two positioning pins 60 are fitted in the fitting holes 810.

The body portion 81 of the second housing member 8 includes a suction port 83 and a discharge port 84 that are open toward the accommodation chamber 20. The suction port 83 and the discharge port 84 have the shape of arc-shaped grooves, and extend in the rotational direction of the inner rotor 31 and the outer rotor 32. The suction port 83 and the discharge port 84 are recessed in the axial direction from the flat surface 8a of the second housing member 8 facing the first housing member 7.

In the suction stroke in which the volume of the pump chamber 30 increases, oil flows from the suction port 83 into the pump chamber 30. In a discharge stroke in which the volume of pump chamber 30 is reduced, oil flows out of pump chamber 30 into discharge port 84. Therefore, the pump unit 3 sucks oil from the suction port 83 by a pump operation composed of a suction stroke and a discharge stroke, and discharges the sucked oil from the discharge port 84.

The second housing member 8 includes a cylindrical suction conduit portion 85. The hollow portion of the suction conduit portion 85 serves as a suction flow path 850 that guides oil into the suction port 83. The second housing member 8 further includes a cylindrical discharge conduit portion 86. The hollow portion of the discharge conduit portion 86 serves as a discharge flow path 860 that guides the oil from the discharge port 84 to the outside. The suction duct portion 85 and the discharge duct portion 86 protrude from the body portion 81 in the axial direction. The pump device 1 sucks oil into the suction flow path 850, and supplies the sucked oil from the discharge flow path 860 to a subject to which the oil is to be supplied.

The pump apparatus 1 further includes a pressure relief valve 9, and the pressure relief valve 9 opens when the hydraulic pressure (oil pressure) in the discharge port 84 becomes equal to or greater than a predetermined value. When the pressure relief valve 9 is opened, a portion of the oil that has flowed into the discharge port 84 from the pump chamber 30 is discharged to the low-pressure side in the discharge stroke, without being supplied to the subject to which the oil is to be supplied. In the present embodiment, when the pressure relief valve 9 is opened, a part of the oil in the drain port 84 is drained to the oil pan. However, the flow path may be provided such that a portion of the oil is discharged to the suction flow path 850.

The pressure relief valve 9 includes a valve body 91, a coil spring 92, and a retaining ring 93. The coil spring 92 is a biasing member that biases the valve body 91 in the valve closing direction. The coil spring 92 is in contact with the retaining ring 93. In the present embodiment, the valve body 91 is spherical, and the coil spring 92 is compressed between the valve body 91 and the retaining ring 93. In the present embodiment, the coil spring 92 has a partial cone shape having a smaller inner diameter as it approaches the end portion thereof contacting the valve body 91.

The second housing member 8 includes a pressure relief flow path 87 that opens toward the groove bottom surface 84a of the discharge port 84. When the pressure relief valve 9 is opened, oil flows from the discharge port 84 to the low pressure side through the relief flow path 87. The pressure relief flow path 87 is formed by a small diameter hole 871 and a large diameter hole 872 which communicate with each other. The small-diameter hole 871 is provided on the discharge port 84 side. The small-diameter hole 871 has an inner diameter smaller than the diameter of the valve body 91, and the large-diameter hole 872 has an inner diameter larger than the diameter of the valve body 91. The step surface between the small-diameter hole 871 and the large-diameter hole 872 is a tapered seating surface 87 a. The valve body 91 contacts the tapered seating surface 87a due to the biasing force of the coil spring 92.

The relief flow path 87 includes an opening 87b provided in the groove bottom surface 84a of the discharge port 84. The valve body 91, the coil spring 92, and the opening 87b of the pressure relief flow path 87 are arranged in the axial direction, and the valve body 91 and the coil spring 92 are accommodated in the large-diameter hole 872 of the pressure relief flow path 87. A large-diameter hole 872 is provided in the second housing member 8. Specifically, a large-diameter hole 872 is provided in the tubular portion 88, and the pressure relief flow path 87 is included in the tubular portion 88. The tubular portion 88 has a cylindrical shape and has a large-diameter hole 872 in the center. The tubular portion 88 accommodates the valve body 91 and the coil spring 92, and the retaining ring 93 is press-fitted in the open end of the tubular portion 88. The grommet 93 has a ring shape. When the pressure relief valve 9 is opened, oil is discharged from the inside of the retaining ring 93 into the oil pan.

As shown in fig. 1B, when the hydraulic pressure in the discharge port 84 is less than the predetermined value, the valve body 91 is in contact with the seating surface 87a due to the urging force (restoring force) of the coil spring 92, and the pressure relief valve 9 is in the closed state. As shown in fig. 1C, when the hydraulic pressure in the discharge port 84 becomes equal to or higher than a predetermined value, the coil spring 92 is compressed and the valve body 91 is retracted. Thus, the pressure relief valve 9 is opened, with the valve body 91 separated from the seating surface 87 a. Therefore, the oil flows into the large-diameter hole 872 through the clearance between the valve body 91 and the seating surface 87 a.

The coil spring 92 extends and contracts along a central axis C (shown in FIG. 1A) of the tubular portion 88. In the present embodiment, the central axis C of the tubular portion 88 is parallel to the rotation axis O of the rotor shaft 43, and the direction in which the coil spring 92 extends and contracts is a direction parallel to the rotation axis O of the rotor shaft 43. The central axis C of the tubular portion 88 and the direction in which the coil spring 92 extends and contracts may be slightly inclined with respect to the rotation axis O. In other words, the central axis C of the tubular portion 88 and the direction in which the coil spring 92 extends and contracts need only be substantially parallel to the rotational axis O.

As shown in fig. 4A, when the second housing member 8 is viewed in the axial direction, the tubular portion 88 is located entirely radially inward of the outer peripheral surface 81a of the body portion 81. In other words, when the second housing member 8 is viewed in the axial direction, the tubular portion 88 does not project radially outward beyond the outer peripheral surface 81a of the body portion 81. The tubular portion 88 is less likely to interfere with the constituent members of the transmission case 10. The central axis C may be inclined with respect to the rotation axis O in such a range that the tubular portion 88 does not protrude outward in the radial direction beyond the outer peripheral surface 81a of the body portion 81 when the second housing member 8 is viewed in the axial direction (in such a range that the tubular portion 88 is located completely inside in the radial direction of the outer peripheral surface 81a of the body portion 81 when the second housing member 8 is viewed in the axial direction). When the inclination of the center axis C with respect to the rotation axis O is within this range, it is easy to avoid the tubular portion 88 from interfering with the constituent members in the transmission housing 10.

The tubular portions 88 lie on the pitch circle C₁And outer diameter circle C₂Inside, the pitch circle C₁The outer diameter circle C passing through the center point of the plurality of bolt insertion holes 820₂An outer peripheral surface 4a of the electric motor unit 4 (an outer diameter of a portion of the motor housing 44 surrounding the stator core 41) is indicated. With this arrangement, it is not necessary to increase the size of the opening 100 in order to insert the tubular portion 88 into the opening 100 of the transmission case 10.

Fig. 5 is a sectional view of the second housing member 8 and the pressure relief valve 9 taken along the line V-V in fig. 4B, i.e., in the direction in which the discharge port 84 extends. Discharge port 84 includes a start 841, a finish 842, and a central portion 843. The start 841 is one end in the direction in which the discharge port 84 extends, and the pump chamber 30 communicates with the start 841 in the initial stage of the discharge stroke. The tip 842 is the other end in the direction in which the discharge port 84 extends, and the pump chamber 30 communicates with the tip 842 in the final stage of the discharge stroke. The central portion 843 corresponds to an intermediate position between the start 841 and end 842. The discharge port 84 is shallower in the starting end 841 and the ending end 842 than in the central portion 843. The discharge flow path 860 communicates with the discharge port 84 at a position near the center portion 843. The deepest portion 840 of the discharge port 84 is positioned closer to the tip 842 than the central portion 843.

The opening 87b of the relief flow path 87 is provided in the groove bottom surface 84a of the start 841 of the discharge port 84. The groove bottom surface 84a between the start end 841 and the central portion 843 of the discharge port 84 is inclined such that the axial depth of the discharge port 84 gradually increases from the start end 841 toward the central portion 843. Groove bottom surface 84a may be configured such that the axial depth of discharge port 84 gradually increases from start 841 toward central portion 843. When the groove bottom surface 84a is such an inclined surface that the axial depth of the discharge port 84 gradually increases from the starting end 841 toward the central portion 843, the oil stably flows in the discharge port 84.

As described above, the opening 87b of the relief flow path 87 is provided in the groove bottom surface 84a of the start 841 of the discharge port 84, where the depth from the flat surface 8a is relatively shallow. In this case, the height H of the tubular portion 88 from the flat surface 8a is smaller than in the case where the opening 87b is provided near the central portion 843, for example. The tubular portion 88 is therefore less likely to interfere with the constituent members in the transmission housing 10 in the axial direction of the pump device 1. The height of the suction duct portion 85 and the discharge duct portion 86 from the flat surface 8a is higher than the height of the tubular portion 88 from the flat surface 8 a. However, because the oil duct is connected to the suction duct portion 85 and the discharge duct portion 86, there is no need to consider interference of the suction duct portion 85 and the discharge duct portion 86 with the constituent members in the transmission case 10.

FIG. 6 is a graph showing the measurement point P in the beginning 841 and end 842 of the discharge port 84 with the pressure relief valve 9 closed₁、P₂(shown in fig. 5) a graph of the measurement results of the relationship between the oil flow and the oil pressure measured at the point. A hole with a small diameter is provided in the second housing member 8, and measurement is performed with a pressure sensor inserted into the discharge port through this hole. The pulsation instantaneous values are averaged and plotted on a graph.

As shown in FIG. 6, for measurement point P in tip 842₂And a measurement point P in the start 841₁Both of these, as the oil flow increases, the oil pressure increases. At any flow rate, the point P is measured₂The oil pressure is higher than the measuring point P₁The oil pressure of the oil. At the measuring point P₂And a measuring point P₁This pressure difference therebetween is regarded as an amount corresponding to an increase in pressure caused when the oil that has flowed out of the pump chamber 30 with the rotation of the inner rotor 31 hits the inner surface of the discharge port 84 on the tip 842 side, etc., due to the inertia of the oil.

In order to appropriately open the pressure relief valve 9 in accordance with the discharge pressure of the oil, it is desirable to minimize the influence of the pressure increase caused by the inertia of the oil flow so that the pressure relief valve 9 does not open due to this pressure increase. In the present embodiment, since the opening 87b of the pressure relief flow path 87 is provided in the groove bottom surface 84a of the start 841 of the discharge port 84, the valve body 91 receives the oil of which dynamic pressure is reduced, and the pressure relief valve 9 opens at an appropriate pressure set by the spring constant and the compression amount of the coil spring 92.