OIL PUMP

An oil pump includes: an outer rotor including internal teeth; an inner rotor including external teeth meshing with the internal teeth; a drive shaft connected to the inner rotor and configured to rotationally drive the inner rotor; and a housing including a pump chamber accommodating the inner and outer rotors. In the housing, a suction port and a discharge port are formed. The discharge port includes a first discharge port and a second discharge port. The suction port includes first and second suction ports respectively disposed on the same side as the first and second discharge ports. A pressure reducing oil passage communicating with the second discharge port and configured to reduce pressure of oil in the second discharge port is formed on the side of the second discharge port.

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Description
CROSS REFERENCE TO RELATED APPLICATIONS

This application is based on and claims priority under 35 U.S.C. § 119 to Japanese Patent Application 2020-073053, filed on Apr. 15, 2020, the entire content of which is incorporated herein by reference.

TECHNICAL FIELD

This disclosure relates to an oil pump.

BACKGROUND DISCUSSION

An oil pump includes an outer rotor including internal teeth, an inner rotor including external teeth, a housing accommodating the outer rotor and the inner rotor, and a drive shaft connected to the inner rotor. A suction port through which oil is suctioned into a pump chamber and a discharge port through which the oil in the pump chamber is discharged are formed in the housing. In the oil pump, the oil is pumped from the suction port to the discharge port by rotating the inner rotor disposed eccentrically with respect to the outer rotor by the drive shaft. Such an oil pump is disclosed in, for example, WO2019/208073 (Reference 1).

In the oil pump disclosed in Reference 1, the discharge port includes a bag structure region communicating with the suction port with the pump chamber sandwiched therebetween, and an open region continuous with a discharge oil passage. Here, at a time of operation of the oil pump, a positive pressure constantly acts on a side of the discharge port. Therefore, in the discharge port, a pressure of the oil in the bag structure region is higher than a pressure of the oil in the open region. In this way, since a pressure difference of the oil is present in the housing, the outer rotor is pressed toward an open region side of the discharge port in the pump chamber, and a sliding friction (rotational resistance) of a pump rotor with respect to an inner surface of the housing is increased. As a result, it is difficult for the oil to flow, and vibration and noise easily occur.

In the oil pump using a motor as a drive source, when an input voltage to the motor is constant, a drive torque of the motor decreases as a motor rotation speed increases, and a motor current decreases. Here, an oil discharge amount of the electric oil pump is proportional to the motor rotation speed. Therefore, when the motor rotation speed increases and the motor current decreases, the oil discharge amount per unit current increases, and a pump efficiency increases. However, when the rotational resistance of the outer rotor increases due to the outer rotor being pressed toward the open region side of the discharge port and the motor rotation speed decreases, the drive torque increases and the motor current increases. As a result, the oil discharge amount per unit current decreases, and the pump efficiency decreases.

A need thus exists for an oil pump which is not susceptible to the drawback mentioned above.

SUMMARY

A characteristic configuration of an oil pump according to this disclosure resides in that the oil pump includes: an outer rotor including internal teeth; an inner rotor including external teeth meshing with the internal teeth; a drive shaft connected to the inner rotor and configured to rotationally drive the inner rotor; and a housing including a pump chamber accommodating the inner rotor and the outer rotor. In the housing, a suction port through which oil is suctioned into the pump chamber and a discharge port through which the oil in the pump chamber is discharged are formed. The discharge port includes a first discharge port directly connected to a discharge oil passage and a second discharge port with the pump chamber sandwiched therebetween. The suction port includes a first suction port disposed on the same side as the first discharge port and a second suction port disposed on the same side as the second discharge port with the pump chamber sandwiched therebetween. A pressure reducing oil passage that communicates with the second discharge port and configured to reduce pressure of the oil in the second discharge port is formed on a side of the second discharge port of the discharge port.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and additional features and characteristics of this disclosure will become more apparent from the following detailed description considered with the reference to the accompanying drawings, wherein:

FIG. 1 is a side sectional view of an oil pump;

FIG. 2 is a cross-sectional view taken along a line II-II of FIG. 1;

FIG. 3 is a cross-sectional view taken along a line III-Ill of FIG. 1;

FIG. 4 is a graph illustrating a relationship between a discharge pressure and a current and a flow rate in an example and a comparative example;

FIG. 5 is a cross-sectional view of main parts of a modification of a first embodiment;

FIG. 6 is a cross-sectional view of main parts of a second embodiment;

FIG. 7 is a cross-sectional view of main parts of a modification of the second embodiment;

FIG. 8 is a cross-sectional view of main parts of a third embodiment; and

FIG. 9 is a cross-sectional view of main parts of another embodiment.

 DETAILED DESCRIPTION

Hereinafter, an oil pump according to embodiments disclosed here will be described with reference to the drawings.

As illustrated in FIG. 1, an oil pump 1 includes a pump portion 10 and a motor portion 30.

The pump portion 10 includes a pump body 11, a pump rotor 14, and a pump cover 18. The pump body 11 and the pump cover 18 are examples of a housing. The pump rotor 14 includes an inner rotor 15 and an outer rotor 16. The motor portion 30 is disposed adjacent to the pump portion 10. The motor portion 30 includes a motor body 31, a motor rotor 32, a stator 33, and a motor cover 34. The motor body 31 is an example of the housing.

As illustrated in FIGS. 1 and 2, the pump body 11 has a cylindrical outer shape, and an inside thereof is formed as a pump chamber 12 for accommodating the pump rotor 14. The pump cover 18 is disposed adjacent to the pump body 11. The pump cover 18 and the pump body 11 are fastened and integrated by a screw (not illustrated). The pump cover 18 and the motor body 31 are formed with a suction port 41 through which oil is suctioned into the pump chamber 12 and a discharge port 42 through which the oil in the pump chamber 12 is discharged.

The discharge port 42 includes a first discharge port 42a and a second discharge port 42b with the pump chamber 12 sandwiched therebetween. The suction port 41 includes a first suction port 41a disposed on the same side as the first discharge port 42a and a second suction port 41b disposed on the same side as the second discharge port 42b with the pump chamber 12 sandwiched therebetween. In the present embodiment, the first suction port 41a and the first discharge port 42a are formed in the pump cover 18, and the second suction port 41b and the second discharge port 42b are formed in the motor body 31. In the pump cover 18, a suction oil passage 43 extends outward from the first suction port 41a, and a discharge oil passage 44 extends outward from the first discharge port 42a.

A bearing hole 19 is formed at a position eccentric from an axial center of the pump chamber 12, and a rotating shaft 13 (an example of a drive shaft) that rotationally drives the inner rotor 15 is inserted and connected so as to penetrate the bearing hole 19 and the inner rotor 15. The rotating shaft 13 is rotatably supported by the bearing hole 19, and the rotating shaft 13 and the inner rotor 15 have a common axis center X and rotate integrally.

In the motor portion 30, the motor rotor 32 is formed in a cylindrical shape, and the annular stator 33 is disposed outside the motor rotor 32. Both the motor rotor 32 and the stator 33 are coaxial with the axial center X. The motor rotor 32 is formed by accommodating and fixing a magnet 36 inside a cylindrical rotor yoke 35 formed by laminating electromagnetic steel plates, and rotates integrally with the rotating shaft 13. The stator 33 includes a stator core 37 in which electromagnetic steel plates are laminated, a coil support frame 38 of an insulator that covers teeth of the stator core 37, and a coil 39 wound from above the coil support frame 38. An alternating current is applied to the coil 39 by power supply from an external driver unit. The motor rotor 32 is rotated by repetition of attraction and repulsion between the coil 39 and the magnet 36 by the alternating current, and the inner rotor 15 is rotated accordingly.

As illustrated in FIG. 2, the pump rotor 14 is configured such that external teeth 15a formed on the inner rotor 15 and internal teeth 16a formed on the outer rotor 16 mesh with each other, and an axial center of the outer rotor 16 coincides with the axial center of the pump chamber 12. When the inner rotor 15 rotates, the outer rotor 16 rotates around the inner rotor 15. A plurality of cells 17 whose volume increases and decreases with the rotation are formed between the external teeth 15a of the inner rotor 15 and the internal teeth 16a of the outer rotor 16. The oil is stored in the cells 17.

As illustrated in FIGS. 2 and 3, the suction ports 41a and 41b and the discharge ports 42a and 42b are crescent-shaped grooves. The suction ports 41a and 41b are formed so as to communicate with the cells 17 along a direction in which the volume of the cells 17 increases when the pump rotor 14 rotates, and the discharge ports 42a and 42b are formed so as to communicate with the cells 17 along a direction in which the volume of the cells 17 decreases when the pump rotor 14 rotates. FIG. 3 illustrates the second suction port 41b and the second discharge port 42b.

Since the volume of the cell 17 communicating with the suction port 41 increases as the pump rotor 14 rotates, negative pressure is generated in the cells 17 and the oil is suctioned from the suction port 41. Thereafter, since the volume of the cells 17 communicating with the discharge port 42 in a state where the oil is stored decreases as the pump rotor 14 rotates, positive pressure is generated in the cells 17 and the oil is discharged toward the discharge port 42. The oil discharged to the discharge port 42 is pumped through the discharge oil passage 44.

As illustrated in FIGS. 1 to 3, a lubrication groove 45 is formed in an inner peripheral region of the motor body 31 facing the rotating shaft 13. The lubrication groove 45 communicates with the second discharge port 42b, and is provided to lubricate the rotating shaft 13 by allowing the oil to enter a gap between the bearing hole 19 and the rotating shaft 13.

As described above, in the oil pump 1, the oil is discharged in a state where the pressure of the oil (hereinafter, also referred to as “oil pressure”) in the discharge port 42 is increased. Here, in the discharge port 42, the first discharge port 42a is connected to the discharge oil passage 44, whereas the second discharge port 42b communicates with the pump chamber 12 but is not connected to the discharge oil passage 44. Therefore, oil pressure in the second discharge port 42b is higher than oil pressure in the first discharge port 42a. In this case, the outer rotor 16 is easily pressed toward the first discharge port 42a by the oil pressure in the second discharge port 42b, and friction is easily generated in the pump chamber 12.

Therefore, in the present embodiment, as illustrated in FIGS. 1 and 3, the motor body 31 includes a first groove portion 51 formed by extending from the second discharge port 42b to the outside. The first groove portion 51 is provided to maintain a pressure balance of the pump chamber 12. That is, the first groove portion 51 is a pressure reducing oil passage 50 that reduces the pressure of the oil in the second discharge port 42b, and functions as a pressure balance groove. That is, since a part of the oil in the second discharge port 42b flows through the pressure reducing oil passage 50 (first groove portion 51), the pressure of the oil in the second discharge port 42b can be reduced. Specifically, the oil in the second discharge port 42b flows out to the outside via the first groove portion 51 (the pressure reducing oil passage 50). Accordingly, since the oil pressure in the second discharge port 42b is reliably reduced, the outer rotor 16 is less likely to be pressed toward a first discharge port 42a side, and the rotational resistance of the pump rotor 14 in the pump chamber 12 can be reduced. As a result, in the oil pump 1, smooth rotation of the pump rotor 14 can be implemented, and pump efficiency can be improved.

Test Example

Using the electric oil pump (example) having the first groove portion 51 (groove) and an electric oil pump (comparative example) not having the first groove portion 51 (groove), a driving current (current) supplied to the motor portion 30 and a flow rate of the oil per unit time accompanying a change in the discharge pressure of the oil were measured. FIG. 4 illustrates a change in the current and the flow rate with respect to the discharge pressure of the oil as a test result. As illustrated in FIG. 4, it was demonstrated that the electric oil pump “with the groove” has a lower current value corresponding to the discharge pressure and a higher flow rate, that is, higher pump efficiency, than the electric oil pump “without the groove”.

[Modification of First Embodiment]

The above embodiment illustrates an example in which the pressure reducing oil passage 50 is formed of the first groove portion 51 formed in the motor body 31, and the pressure reducing oil passage 50 may be constituted by forming a groove portion over two members. In a modification illustrated in FIG. 5, the first groove portion 51 formed in the motor body 31 is shortened, and a second groove portion 52 communicating with the first groove portion 51 and communicating with an outside is formed in the pump body 11. That is, in the present modification, the pressure reducing oil passage 50 includes the first groove portion 51 formed in the motor body 31 and the second groove portion 52 formed in the pump body 11.

Second Embodiment

As illustrated in FIG. 6, in the second embodiment, as the pressure reducing oil passage 50, a third groove portion 53 is formed in the motor body 31 from the second discharge port 42b toward a suction port (the second suction port 41b in the present embodiment) on the same side. The second suction port 41b is formed in a crescent shape along a portion where the internal teeth 16a of the outer rotor 16 and the external teeth 15a of the inner rotor 15 mesh with each other as viewed in a direction along the axial center X, and one end side 41b1 of both ends in a longitudinal direction is formed to be wider than the other end side 41b2. Specifically, in the second suction port 41b, a width W1 of the one end side 41b1 is larger than a width W2 of the other end side 41b2. Further, the second discharge port 42b is formed in a crescent shape along the portion where the internal teeth 16a of the outer rotor 16 and the external teeth 15a of the inner rotor 15 mesh with each other as viewed in the direction along the axial center X, and one end side 42b1 of both ends in the longitudinal direction is formed to be wider than the other end side 42b2. Specifically, in the second discharge port 42b, a width W3 of the one end side 42b1 is larger than a width W4 of the other end side 42b2. The one end side 41b1 of the second suction port 41b and the one end side 42b1 of the second discharge port 42b face each other, and the other end side 41b2 of the second suction port 41b and the other end side 42b2 of the second discharge port 42b face each other.

The third groove portion 53 (pressure reducing oil passage 50) communicates with the other end side 42b2 of the second discharge port 42b, and is formed over the other end side 41b2 of the second suction port 41b. Further, the third groove portion 53 (pressure reducing oil passage 50) is formed outside the second discharge port 42b and the second suction port 41b with respect to the rotating shaft 13. Therefore, oil in the second discharge port 42b can be returned to the second suction port 41b via the third groove portion 53 (pressure reducing oil passage 50). Accordingly, oil pressure in the second discharge port 42b can be reliably reduced, and the oil pump 1 can effectively use the oil in the second discharge port 42b without discharging the oil to the outside.

FIG. 6 illustrates virtual straight lines (one-dotted lines) L1 and L2 obtained by connecting the axial center X of the rotating shaft 13 and both ends 53a and 53b of the third groove portion 53 (pressure reducing oil passage 50). In FIG. 6, in the third groove portion 53, an end portion on a side of the suction port 41 is indicated by 53a, and an end portion on a side of the discharge port 42 is indicated by 53b. In the third groove portion 53, an angle θ formed by the two virtual straight lines L1 and L2 on a side where the third groove portion 53 is formed around the axial center X is preferably 180 degrees or more. In the example illustrated in FIG. 6, the angle θ is 180 degrees or more. Accordingly, the third groove portion 53 can ensure a wide region in which the oil in the second discharge port 42b flows. As a result, the oil pump 1 can reliably reduce the oil pressure in the second discharge port 42b by the third groove portion 53 (pressure reducing oil passage 50).

In the present embodiment, as described above, when viewed in the direction along the rotating shaft 13, in the second discharge port 42b formed in the crescent shape, the one end side 42b1 of both ends in the longitudinal direction is wider than the other end side 42b2. Here, in the oil pump 1, since the discharge port 42 increases the oil pressure to discharge the oil, the oil pressure on the other end side 42b2 with a narrow width is more likely to increase than that on the one end side 42b1 with a wide width. Therefore, in the present embodiment, the third groove portion 53 (pressure reducing oil passage 50) is formed so as to communicate with the other end side 42b2 having the narrow width of the second discharge port 42b. Accordingly, the oil pressure in the second discharge port 42b can be more effectively reduced.

(Modification of Second Embodiment)

As illustrated in FIG. 7, the third groove portion 53 (pressure reducing oil passage 50) may communicate with the one end side 42b1 of the second discharge port 42b and may be formed over the one end side 41b1 of the second suction port 41b. Even in a modification illustrated in FIG. 7, the angle θ formed by the two virtual straight lines L1 and L2 on a side where the third groove portion 53 (pressure reducing oil passage 50) is formed around the axial center X is 180 degrees or more. Further, although not illustrated, the third groove portion 53 (pressure reducing oil passage 50) may be formed to communicate with the one end side 42b1 of the second discharge port 42b and to extend over the other end side 41b2 of the second suction port 41b, or may be formed to communicate with the other end side 42b2 of the second discharge port 42b and to extend over the one end side 41b1 of the second suction port 41b.

Third Embodiment

The above embodiment illustrates an example in which the pressure reducing oil passage 50 is provided by the groove portions 51 and 52 formed in the motor body 31 or the pump body 11. In a third embodiment, as illustrated in FIG. 8, the pressure reducing oil passage 50 is formed of a through hole 54 formed in the motor body 31. Since the pressure reducing oil passage 50 is formed with the through hole 54 instead of the groove portion, a degree of freedom of a shape and arrangement of the pressure reducing oil passage 50 is increased. Further, in the present embodiment, the motor body 31 and the pump body 11 may be integrally formed. Accordingly, the number of components of the oil pump 1 can be reduced.

Other Embodiments

(1) The above embodiments illustrate an example in which the suction oil passage 43 and the discharge oil passage 44 are provided on the pump cover 18. As illustrated in FIG. 9, the suction oil passage 43 and the discharge oil passage 44 may be provided in the motor body 31. In this case, the first suction port 41a and the first discharge port 42a are formed in the motor body 31, and the second suction port 41b and the second discharge port 42b are formed in the pump cover 18. Although not illustrated, the suction oil passage 43 may be provided in one of the motor body 31 and the pump cover 18, and the discharge oil passage 44 may be provided in the other of the motor body 31 and the pump cover 18. For example, when the suction oil passage 43 is provided in the motor body 31 and the discharge oil passage 44 is provided in the pump cover 18, the pump cover 18 is provided with the first suction port 41a and the first discharge port 42a, the motor body 31 is provided with the second suction port 41b and the second discharge port 42b, the suction oil passage 43 communicates with the second suction port 41b, and the discharge oil passage 44 communicates with the first discharge port 42a.

In an arrangement of the suction port 41 and the discharge port 42 illustrated in FIG. 9, in the first to third embodiments described above, the first groove portion 51, the third groove portion 53, and the through hole 54 illustrated as the pressure reducing oil passage 50 are formed in the pump cover 18. FIG. 9 illustrates an example in which the first groove portion 51 is formed in the pump cover 18.

(2) The above embodiments illustrate an example in which a drive source of the rotating shaft 13 is an electric motor, but the drive source of the rotating shaft 13 is not limited to the electric motor. The drive source of the rotating shaft 13 may be, for example, a crankshaft of an internal combustion engine.

(3) The inner rotor 15 and the outer rotor 16 are not limited to those having the shape and the support structure described in the above embodiments, and can be appropriately changed.

INDUSTRIAL APPLICABILITY

This disclosure can be widely used in an oil pump.

A characteristic configuration of an oil pump according to this disclosure resides in that the oil pump includes: an outer rotor including internal teeth; an inner rotor including external teeth meshing with the internal teeth; a drive shaft connected to the inner rotor and configured to rotationally drive the inner rotor; and a housing including a pump chamber accommodating the inner rotor and the outer rotor. In the housing, a suction port through which oil is suctioned into the pump chamber and a discharge port through which the oil in the pump chamber is discharged are formed. The discharge port includes a first discharge port directly connected to a discharge oil passage and a second discharge port with the pump chamber sandwiched therebetween. The suction port includes a first suction port disposed on the same side as the first discharge port and a second suction port disposed on the same side as the second discharge port with the pump chamber sandwiched therebetween. A pressure reducing oil passage that communicates with the second discharge port and configured to reduce pressure of the oil in the second discharge port is formed on a side of the second discharge port of the discharge port.

In the oil pump, the oil is discharged in a state where pressure of the oil is increased in the discharge port. Here, in the discharge port, the first discharge port is connected to the discharge oil passage, whereas the second discharge port communicates with the pump chamber but is not connected to the discharge oil passage. Therefore, the pressure of the oil in the second discharge port is higher than the pressure of the oil in the first discharge port. In this case, the outer rotor at the pump rotor is easily pressed toward the first discharge port by the pressure of the oil in the second discharge port, and friction is easily generated in the pump chamber. Therefore, in the present configuration, the pressure reducing oil passage that communicates with the second discharge port and reduces pressure of oil in the second discharge port is formed on the side of the second discharge port which is a side opposite to the first discharge port connected to the discharge oil passage. Therefore, since a part of the oil in the second discharge port flows through the pressure reducing oil passage, the pressure of the oil in the second discharge port can be reduced. Accordingly, the outer rotor is less likely to be pressed toward the first discharge port side, and the rotational resistance of the pump rotor in the oil pump can be stably reduced. As a result, in the oil pump, smooth rotation of the pump rotor can be implemented, and pump efficiency can be improved.

Another characteristic configuration resides in that the pressure reducing oil passage is formed from the second discharge port to an outside.

According to the present configuration, since the pressure reducing oil passage is formed from the second discharge port to the outside, the oil in the second discharge port can flow out to the outside via the pressure reducing oil passage. Therefore, the pressure of the oil in the second discharge port can be reliably reduced.

Another characteristic configuration resides in that the pressure reducing oil passage is formed from the second discharge port to the second suction port.

According to the present configuration, since the pressure reducing oil passage is formed from the second discharge port to the second suction port, the oil in the second discharge port can be returned to the second suction port via the pressure reducing oil passage. Accordingly, the pressure of the oil in the second discharge port can be reliably reduced, and the oil pump can effectively use the oil in the second discharge port without discharging the oil to the outside.

Another characteristic configuration resides in that the pressure reducing oil passage is formed outside the second discharge port and the second suction port with respect to the drive shaft, and an angle formed by two virtual straight lines on the side where the pressure reducing oil passage is formed when an axial center of the drive shaft is connected to both ends of the pressure reducing oil passage by the virtual straight lines is 180 degrees or more.

According to the present configuration, the pressure reducing oil passage formed from the second discharge port to the second suction port is formed around the axial center of the drive shaft at an angle of 180 degrees or more. Accordingly, the pressure reducing oil passage can ensure a wide region in which the oil in the second discharge port flows. As a result, the oil pump can reliably reduce the pressure of the oil in the second discharge port by the pressure reducing oil passage.

Another characteristic configuration resides in that the second discharge port is formed in a crescent shape along a portion where the internal teeth of the outer rotor and the external teeth of the inner rotor mesh with each other as viewed in a direction along the drive shaft, one end side of both ends in a longitudinal direction is formed to be wider than the other end side, and the pressure reducing oil passage is formed so as to communicate with the other end side of the second discharge port.

According to the present configuration, when viewed in the direction along the drive shaft, the second discharge port formed in the crescent shape is formed such that one end side of both ends in the longitudinal direction is wider than the other end side. Here, in the oil pump, since the discharge port increases the pressure of the oil to discharge the oil, the pressure of the oil on the other end side with a narrow width is more likely to increase than that on the one end side with a wide width. Therefore, in the present configuration, the pressure reducing oil passage is formed so as to communicate with the other end side with the narrow width of the second discharge port. Accordingly, the pressure of the oil in the second discharge port can be more effectively reduced.

Another characteristic configuration resides in that the pressure reducing oil passage is formed of a groove formed in the housing.

According to the present configuration, since the pressure reducing oil passage is formed of the groove formed in the housing, the pressure reducing oil passage can be easily formed in the oil pump.

The principles, preferred embodiment and mode of operation of the present invention have been described in the foregoing specification. However, the invention which is intended to be protected is not to be construed as limited to the particular embodiments disclosed. Further, the embodiments described herein are to be regarded as illustrative rather than restrictive. Variations and changes may be made by others, and equivalents employed, without departing from the spirit of the present invention. Accordingly, it is expressly intended that all such variations, changes and equivalents which fall within the spirit and scope of the present invention as defined in the claims, be embraced thereby.

Claims

1. An oil pump comprising:

an outer rotor including internal teeth;
an inner rotor including external teeth meshing with the internal teeth;
a drive shaft connected to the inner rotor and configured to rotationally drive the inner rotor; and
a housing including a pump chamber accommodating the inner rotor and the outer rotor, wherein
in the housing, a suction port through which oil is suctioned into the pump chamber and a discharge port through which the oil in the pump chamber is discharged are formed,
the discharge port includes a first discharge port directly connected to a discharge oil passage and a second discharge port with the pump chamber sandwiched therebetween,
the suction port includes a first suction port disposed on the same side as the first discharge port and a second suction port disposed on the same side as the second discharge port with the pump chamber sandwiched therebetween, and
a pressure reducing oil passage communicating with the second discharge port and configured to reduce pressure of the oil in the second discharge port is formed on the side of the second discharge port of the discharge port.

2. The oil pump according to claim 1, wherein

the pressure reducing oil passage is formed from the second discharge port to an outside.

3. The oil pump according to claim 1, wherein

the pressure reducing oil passage is formed from the second discharge port to the second suction port.

4. The oil pump according to claim 3, wherein

the pressure reducing oil passage is formed outside the second discharge port and the second suction port with respect to the drive shaft, and an angle formed by two virtual straight lines on the side where the pressure reducing oil passage is formed when an axial center of the drive shaft is connected to both ends of the pressure reducing oil passage by the virtual straight lines is 180 degrees or more.

5. The oil pump according to according to claim 1, wherein

the second discharge port is formed in a crescent shape along a portion where the internal teeth of the outer rotor and the external teeth of the inner rotor mesh with each other as viewed in a direction along the drive shaft, and one end side of both ends in a longitudinal direction is formed to be wider than the other end side, and
the pressure reducing oil passage is formed so as to communicate with the other end side of the second discharge port.

6. The oil pump according to claim 1, wherein

the pressure reducing oil passage is formed of a groove formed in the housing.
Patent History
Publication number: 20210324855
Type: Application
Filed: Mar 19, 2021
Publication Date: Oct 21, 2021
Applicant: AISIN SEIKI KABUSHIKI KAISHA (Kariya-shi)
Inventors: Toshiyuki YOKOI (Kariya-shi), Hirokazu HATA (Kariya-shi), Yusuke NAKAYAMA (Kariya-shi)
Application Number: 17/206,202
Classifications
International Classification: F04C 15/06 (20060101); F04C 2/10 (20060101); F04C 13/00 (20060101);