WO2022176545A1

WO2022176545A1 - Tandem type oil pump

Info

Publication number: WO2022176545A1
Application number: PCT/JP2022/002864
Authority: WO
Inventors: 英俊楊; 亮松村
Original assignee: 日立Astemo株式会社
Priority date: 2021-02-16
Filing date: 2022-01-26
Publication date: 2022-08-25
Also published as: JP2022124700A; CN116897248A

Abstract

The present invention provides a tandem type oil pump in which a high-pressure oil pump and a low-pressure oil pump are combined, wherein a pump rotor (38) of the low-pressure oil pump is configured to be movable in the axial direction with respect to a drive shaft (16). This makes it possible for the pump rotor (38) of the low-pressure oil pump to move in the axial direction of the drive shaft (16). Therefore, even when discharge pressure is low, it is possible to supply oil to a side surface of the pump rotor (38) of the low-pressure oil pump, and possible to prevent seizure or abrasion from occurring on the side surface of the pump rotor (38).

Description

tandem oil pump

The present invention relates to an oil pump, and more particularly to a tandem oil pump having two oil pumps.

A tandem-type oil pump applied to an internal combustion engine mounted on an automobile has a well-known configuration, for example, as disclosed in Japanese Patent Application Laid-Open No. 2008-163925 (Patent Document 1).

A tandem-type oil pump disclosed in Patent Document 1 includes a first pump having the same shape and a second pump arranged with a rotation phase shifted with respect to the first pump, in a pump body formed in a cylindrical shape with a bottom. An annular partition member for partitioning between the pumps, and a pump body slidably supported in the pump body penetrates both pumps and the partition member to transmit driving force to the inner rotors of both pumps. Each pump performs a pumping action when the drive shaft is rotationally driven by the driving force transmitted from the internal combustion engine. The first pump and the second pump are pumps having substantially the same discharge pressure.

Apart from this, a tandem oil pump that combines a high-pressure oil pump and a low-pressure oil pump has also been proposed. For example, a scavenging oil pump (low-pressure oil pump) that collects engine oil (hereinafter simply referred to as oil) from the oil pan, and supplies pressurized oil to the variable valve mechanism and the main oil gallery of the internal combustion engine. BACKGROUND ART A tandem oil pump combined with a variable capacity oil feed pump (high pressure oil pump) is known. A gear-type oil pump is used as the scavenging oil pump, and a vane-type oil pump is used as the variable displacement oil feed pump.

The scavenging oil pump is a pump that simultaneously sucks oil, mist, blow-by gas, etc. from the oil pan. In addition, the sucked oil containing air bubbles and foreign matter is separated by a reservoir tank and a centrifugal separator, pressurized by a variable displacement oil feed pump, and supplied to the variable valve mechanism and the main oil gallery of the internal combustion engine. It is designed to be

The present invention is directed to a tandem-type oil pump in which the high-pressure oil pump and the low-pressure oil pump are combined. is not limited to

JP 2008-163925 A

As shown in Patent Document 1, a drive shaft is engaged with the pump rotor of the first pump and the pump rotor of the second pump, and this drive shaft is used to rotate an internal combustion engine, an electric motor, or the like. It is configured to be rotationally driven by power from a source. In addition, it is necessary to provide a thrust control function so that the drive shaft to which the pump rotor is attached does not move in the axial direction.

For this reason, the pump rotor and the drive shaft are firmly fixed, and the side surface of the pump rotor orthogonal to the axis of the drive shaft is brought into contact with the wall surface of the pump rotor storage section, so that the drive shaft with the pump rotor mounted thereon is moved in the axial direction. I try not to move. In this case, the side surface of the pump rotor rotates while sliding against the wall surface of the pump rotor housing section that houses the pump rotor.

However, when the pump rotor of the low-pressure oil pump is fixed to the drive shaft, the discharge pressure of the low-pressure oil pump is low when the wall surface of the pump rotor housing portion and the side surface of the pump rotor of the low-pressure oil pump come into contact with each other with a high surface pressure. As a result, it becomes difficult to supply sufficient oil to the contact portion between the side surface of the pump rotor and the wall surface of the pump rotor storage section, causing the oil film to run out, which may cause seizure or rapid wear at the contact portion.

SUMMARY OF THE INVENTION An object of the present invention is to provide a novel tandem-type oil pump that can suppress seizure or wear on the side surface of the pump rotor of the low-pressure oil pump when a high-pressure oil pump and a low-pressure oil pump are combined. to provide.

The present invention
a first pump rotor accommodation portion and a second pump rotor accommodation portion; a partition wall that partitions the first pump rotor accommodation portion and the second pump rotor accommodation portion; a pump body having a bearing through-hole connecting between two pump rotor accommodating portions; a drive shaft rotatably disposed in the bearing through-hole and driven to rotate by an external power source; and a first pump rotor. Having a first pump rotor disposed in the housing portion and fixed to the drive shaft so as to restrict relative movement in the drive axis direction and the rotational direction, the first pump rotor being rotationally driven by the drive shaft; a first oil pump that pressurizes the oil introduced from the first suction portion and discharges it from the first discharge portion;
Having a second pump rotor disposed in the second pump rotor accommodating portion, capable of moving relative to the drive shaft in the direction of the drive axis, and restricted from moving relative to the drive shaft in the rotational direction; A second oil pump that rotates the second pump rotor by the drive shaft to discharge the oil introduced from the second suction part from the second discharge part at a pressure lower than the pressure discharged from the first pump. And, it is characterized by having.

In addition, the present invention
a high-pressure pump rotor housing portion and a low-pressure pump rotor housing portion; a partition wall that separates the high-pressure pump rotor housing portion and the low-pressure pump rotor housing portion; a pump body having a drive shaft bearing connecting between
a drive shaft arranged in the high-pressure pump rotor housing and the low-pressure pump rotor housing, and rotatably driven by an external power source rotatably supported by the drive shaft bearing;
High-pressure oil having a high-pressure pump rotor disposed in the high-pressure pump rotor accommodating portion and press-fitted and fixed to the drive shaft. The high-pressure pump rotor is rotationally driven by the drive shaft to perform a pump action at a first discharge pressure. a pump;
It has a low-pressure pump rotor disposed in a low-pressure pump rotor accommodating section and mounted movably in the drive axis direction with respect to the drive shaft. a low-pressure oil pump that performs a pumping action at a low second discharge pressure.

According to the present invention, in a tandem-type oil pump that combines a high-pressure oil pump and a low-pressure oil pump, the second pump rotor (low-pressure pump rotor) can move in the axial direction of the drive shaft. ), a sufficient amount of oil can be supplied to the side surface of the second pump rotor (low-pressure pump rotor), thereby suppressing the seizure phenomenon or wear phenomenon on the side surface of the second pump rotor (low-pressure pump rotor). can do.

In addition, since the high-pressure oil pump has a high discharge pressure, even if the side surface of the first pump rotor (high-pressure pump rotor) comes into contact with the pump housing portion with a large surface pressure, the first oil pump (high-pressure oil pump) will To supply a sufficient amount of oil to the side surface of a first pump rotor (high-pressure pump rotor), and to suppress the occurrence of a seizure phenomenon or a wear phenomenon on the side surface of the first pump rotor (high-pressure pump rotor). can be done.

1 is an external perspective view of a tandem-type oil pump according to an embodiment of the present invention, viewed obliquely from above; FIG. FIG. 2 is a front view of the tandem oil pump shown in FIG. 1 viewed from the side of a variable displacement oil feed pump; FIG. 2 is a rear view of the tandem oil pump shown in FIG. 1 as seen from the scavenging oil pump side; FIG. 2 is an exploded perspective view of a variable displacement oil feed pump, viewed obliquely from above; FIG. 3 is a cross-sectional view for explaining the internal structure of a pump portion of a variable displacement oil feed pump; FIG. 4 is an exploded perspective view of the scavenging oil pump when viewed obliquely from above; FIG. 4 is a cross-sectional view for explaining the internal structure of the pump portion of the scavenging oil pump; FIG. 2 is a sectional view showing the AA section of the tandem oil pump shown in FIG. 1; FIG. 3 is an exploded perspective view for explaining the shapes of the inner rotor and drive shaft of the scavenging oil pump; FIG. 2 is an external perspective view of the tandem oil pump shown in FIG. 1 with a part cut away and viewed obliquely from above; 1. It is the external perspective view which notched a part of modification of the tandem-type oil pump shown in FIG. 1, and was seen from the diagonally upper side. FIG. 3 is an external perspective view of a tandem oil pump as a comparative example, with a part cut away and viewed obliquely from above;

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the following embodiments, and various modifications and applications can be made within the technical concept of the present invention. is also included in the scope.

FIG. 1 shows a tandem-type oil pump according to an embodiment of the present invention as seen obliquely from above. A high-pressure pump cover 13 (corresponding to the first pump cover in the claims) attached at 12, and a low-pressure pump cover 15 (see FIG. 3) attached to the rear portion 11B of the pump body 11 with bolts 14 (see FIG. 3). (corresponding to the second pump cover).

Although the details will be described later, the pump body 11 on the side of the high-pressure pump cover 13 houses a variable displacement oil feed pump, which is a high-pressure oil pump (corresponding to the first pump in the claims). A scavenging oil pump, which is a low-pressure oil pump (corresponding to a second pump in the claims), is accommodated in the pump body 11 on the low-pressure pump cover 15 side. Here, the pump body 11 is formed in a substantially rectangular parallelepiped box shape, but in reality, the shape is changed according to the external shape and size of the internal combustion engine. However, even if the external shape changes, the basic idea of the present invention does not change.

The tandem-type oil pump 10 has a drive shaft 16 extending through the high-pressure pump cover 13 and the pump body 11 to the low-pressure pump cover 15. The drive shaft 16 may be the crankshaft of an internal combustion engine or an external drive such as an electric motor. Rotationally driven by a source. The drive shaft 16 is shared by the high-pressure oil pump and the low-pressure oil pump, and the drive shaft 16 rotates the pump rotors of the high-pressure oil pump and the low-pressure oil pump, respectively.

In addition, on the upper surface portion 11U of the pump body 11 located between the high-pressure pump cover 13 and the low-pressure pump cover 15, a low-pressure side connected to the suction portion (corresponding to the second suction portion in the claims) of the low-pressure oil pump is provided. A suction hole 17 (corresponding to a second suction hole in the claims) is formed.

A pair of attachment portions 11A to be attached to the oil pan of the internal combustion engine are provided on the upper surface portion 11U of the pump body 11. Fixing bolts are inserted through the attachment portions 11A to be fixed to the internal combustion engine. A low-pressure side suction hole 17 is formed in the mounting portion 11A. The pair of attachment portions 11A are provided so as to sandwich the pump body 11 from both sides at radial positions with respect to the drive shaft 16 provided in the pump body 11, and are attached to the internal combustion engine. Therefore, when the tandem-type oil pump 10 is attached to the internal combustion engine, the oil in the oil pan can be easily guided to the low-pressure side suction hole 17 .

FIG. 2 shows the front of the tandem-type oil pump 10 on the side on which the high-pressure pump cover 13 is provided. (pump chamber). The high-pressure pump cover 13 is attached to the pump body 11 along a plane perpendicular to the axis of the drive shaft 16 .

A high-pressure oil pump connected to a discharge portion (corresponding to a first discharge portion in the claims) of the high-pressure oil pump is provided on the high-pressure pump cover 13 located radially outside the drive shaft center of the drive shaft 16 . A side discharge hole 18 (corresponding to a first discharge hole in the claims) is formed. The high-pressure side discharge hole 18 supplies pressurized oil to at least the main oil gallery of the internal combustion engine in this embodiment, but it may also supply the variable valve mechanism.

FIG. 3 shows the rear surface of the tandem-type oil pump 10 on the side where the low-pressure pump cover 15 is provided. forms part of The low-pressure pump cover 15 is attached to the pump body 11 along a plane perpendicular to the axis of the drive shaft 16 . A suction portion (corresponding to a first suction portion in the claims) of a high-pressure oil pump is connected to the rear surface portion 11B of the pump body 11 located radially outside the drive shaft center of the drive shaft 16. A high-pressure side suction hole 19 (corresponding to a first suction hole in the claims) is formed.

The low-pressure pump cover 15 has a low-pressure side discharge hole 20 (corresponding to the second discharge hole in the claims) connected to the discharge part (corresponding to the second discharge part in the claims) of the low-pressure oil pump. is formed.

Next, the configurations of the high-pressure oil pump and the low-pressure oil pump will be described with reference to FIGS. 4 to 7. FIG. FIG. 4 shows the disassembled state of the high-pressure oil pump after the low-pressure oil pump is assembled, and FIG. 6 shows the disassembled state of the low-pressure oil pump after the high-pressure oil pump is assembled. Here, as described above, the high-pressure oil pump is a vane-type oil pump (variable displacement type) using vanes, and the low-pressure pump is a gear-type oil pump using a trochoid gear.

As shown in FIG. 4, one side of the pump body 11 is formed with a vane pump rotor accommodating portion 21 (corresponding to the first pump rotor accommodating portion/high pressure pump rotor accommodating portion in the claims) of the vane type oil pump. Further, as shown in FIG. 6, on the other side of the pump body 11, a gear pump rotor accommodating portion 22 (corresponding to the second pump rotor accommodating portion/low-pressure pump rotor accommodating portion in the claims) of the gear type oil pump is provided. do) is formed. A partition wall 23 that partitions the vane pump rotor accommodating portion 21 and the gear pump rotor accommodating portion 22 is formed between the vane pump rotor accommodating portion 21 and the gear pump rotor accommodating portion 22 .

Since the partition wall 23 is integrally formed with the pump body 11, the vane-type oil pump can be assembled from one side of the pump body 11, and the gear-type oil pump can be assembled from the other side of the pump body 11. can. A bearing through hole 24 (corresponding to a drive shaft bearing portion in the claims) through which the drive shaft 16 passes is formed in the partition wall 23 (see FIG. 8).

　The configuration of the vane-type oil pump will be described using FIGS. 4 and 5, but since this vane-type oil pump has a well-known configuration, the description will be brief. Here, FIG. 5 shows a pump portion of a well-known vane-type oil pump taken in a cross section perpendicular to the axis.

4 and 5, a pump body 25 is housed in a recessed vane pump rotor housing portion 21 formed in the pump body 11. As shown in FIG. A vane pump rotor 26 (corresponding to a first pump rotor/high-pressure pump rotor in the claims) press-fitted with the drive shaft 16 is arranged substantially in the center of the vane pump rotor accommodating portion 21, and a swinging rotor 26 is arranged on the outer side thereof. An adjustment ring 27 is arranged whose dynamic center is eccentric to the drive shaft 16 . Since the vane pump rotor 26 is press-fitted onto the drive shaft 16 in this manner, it is firmly fixed so as to restrict relative movement in the drive axis direction and the rotational direction.

The adjustment ring 27 is pivotable about the pivot 28, and in the initial state, the adjustment ring 27 is pushed rightward in FIG. and the eccentricity is at its maximum setting.

The vanes 31 are arranged in a plurality of slits provided in the vane pump rotor 26, and when the vane pump rotor 26 rotates, the tips of the vanes slide on the inner peripheral surface of the adjustment ring 27 while appearing and disappearing from the outer peripheral surface of the vane pump rotor 26. All of the vanes 31 are supported by vane rings 32 so as not to retreat inward even when stopped.

A space formed by the outer peripheral surface of the vane pump rotor 26, the inner peripheral surface of the adjustment ring 27, and the two vanes 31 (hereinafter referred to as the hydraulic oil chamber) rotates counterclockwise as shown in FIG. The volume increases and decreases as the vane pump rotor 26 rotates. A suction portion 33 is provided on the side surface of the pump body 11 within a range where the volume of the hydraulic oil chamber increases. The suction portion 33 is connected to the high-pressure side suction hole 19 provided in the rear portion 11B of the pump body 11 on the low-pressure oil pump side.

On the other hand, a discharge portion 34 is provided on the side surface of the pump body 11 within a range where the volume of the hydraulic oil chamber is reduced. This discharge portion 34 is connected to a high pressure side discharge hole 18 provided in the front portion 11F of the pump body 11 on the side of the high pressure oil pump.

The vane type oil pump sucks up oil through the suction hole 19 and discharges the oil through the discharge hole 18 to the variable valve mechanism or the main oil gallery of the internal combustion engine to perform a pumping action. The compression spring 35 biases the ball valve 36, and when the discharge pressure rises above a predetermined value, the ball valve 36 is opened to reduce the discharge pressure. Since the configuration and operation of this vane type oil pump are well known, further explanation will be omitted.

Thus, the vane-type oil pump is arranged swingably in the vane pump rotor accommodating portion 21 and accommodated in the adjustment ring 27 having the vane accommodating portion therein, and the drive shaft and a plurality of vanes 31 accommodated on the outer peripheral surface of the vane pump rotor 26 and forming a plurality of hydraulic oil chambers through which oil is directed between the adjustment ring 27 and the vane pump rotor 26. Then, the oil is sucked from the suction hole 19 (see FIG. 3) whose volume increases among the plurality of hydraulic oil chambers as the drive shaft 16 rotates, and It is an oil pump that discharges oil from a discharge hole 18 (see FIG. 2) whose volume decreases.

Next, the configuration of the gear-type oil pump will be described with reference to FIGS. 6 and 7. Since this gear-type oil pump is also well-known, the description will be brief. Here, FIG. 7 shows a pump portion of a known gear-type oil pump taken in a cross section perpendicular to the axis.

In FIG. 6, a gear pump rotor accommodating portion 22 is formed on the side of the rear portion 11B of the pump body 11, and an outer rotor 37 (corresponding to a part of the second pump rotor/low-pressure pump rotor in the claims) is formed therein. ) are slidably and rotatably arranged.

Further, inside the outer rotor 37, an inner rotor 38 (corresponding to a part of the second pump rotor/low-pressure pump rotor in the claims) is arranged. As shown in FIG. 7, five internal teeth 40, one more than the external teeth 39 of the inner rotor 38, are formed on the inner peripheral side of the outer rotor 37. It meshes with the external teeth 39 of the rotor 38 .

A plurality of working oil chambers are formed between the outer teeth 39 of the inner rotor 38 and the inner teeth 40 of the outer rotor 37. When the inner rotor 38 rotates, the outer rotor 37 rotates eccentrically, thereby The volume of the oil chamber increases and decreases, thereby continuously sucking and discharging oil to perform a pump action.

Here, the inner rotor 38 is rotationally driven by the drive shaft 16. In the present embodiment, the inner rotor 38 can move relative to the drive shaft 16 in the direction of the drive axis, and the drive shaft 16 can rotate. Relative movement in the rotational direction is restricted with respect to Specifically, the drive shaft 16 to which the inner rotor 38 is fitted is formed in a shape having a width across flats, and the inner rotor 38 can move in the drive shaft direction at this portion.

Here, the width across flats means a shape formed along the axial direction of the drive shaft 16 and having planes facing each other parallel to each other. Therefore, the inner rotor 38 can move along the axial direction of the drive shaft 16 and rotate together with the drive shaft 16 in the rotational direction.

In this way, the gear-type oil pump is housed inside the gear pump rotor housing portion 22 and also housed inside the outer rotor 37 including the plurality of internal teeth 40 on the inner peripheral side and the outer rotor 37. , and an inner rotor provided on a drive shaft 16 so as to be movable in the direction of the drive axis of the drive shaft 16 and having a plurality of external teeth 39 meshing with a plurality of internal teeth 40 on the outer peripheral side. .

Next, the internal configuration of the tandem-type oil pump 10 shown in FIG. 1 will be described using FIG. 8, which is taken along line AA shown in FIG.

8, a high-pressure pump cover 13 is attached to the pump body 11 with bolts 12 on the front portion 11F of the pump body 11, and a low-pressure pump cover 15 is attached to the pump body 11 with bolts 14 on the rear portion 11B of the pump body 11. installed. A vane-type oil pump, which is a high-pressure oil pump, is accommodated in the pump body 11 on the high-pressure pump cover 13 side, and a gear-type oil pump, which is a low-pressure oil pump, is accommodated in the pump body 11 on the low-pressure pump cover 15 side. Contains the oil pump.

It also has a drive shaft 16 extending through the high-pressure pump cover 13 and the partition wall 23 formed in the pump body 11 and extending to the low-pressure pump cover 15 . The drive shaft 16 is shared by the high-pressure oil pump and the low-pressure oil pump, and rotates the vane pump rotor 26 of the high-pressure oil pump and the inner rotor 38 of the low-pressure oil pump, respectively.

A large diameter portion 16L having a circular cross section is formed on the drive shaft 16, and the large diameter portion 16L is supported by a hole formed in the high pressure pump cover 13. Further, the drive shaft 16 is supported by a bearing through hole 24 provided in the partition wall 23 . Therefore, the drive shaft 16 has a circular cross section at least up to the point where it contacts the partition wall 23 .

The drive shaft 16 abuts on the low-pressure pump cover 15 or extends until just before it abuts, and this portion is not supported by a bearing. Therefore, in the vicinity of the low-pressure pump cover 15, a phenomenon occurs in which the drive shaft 16 vibrates. If the drive shaft 16 touches, the positional relationship between the inner rotor 38 and the outer rotor 37 changes, which may cause abnormal noise and oil leakage from the working oil chamber.

For this reason, in the present embodiment, a small diameter shaft portion 41 (a second pump rotor diameter (corresponding to the small shaft portion/low-pressure pump rotor diameter small shaft portion) are integrally formed. The small-diameter shaft portion 41 has a circular cross section perpendicular to the axis of the drive shaft 16 .

On the side of the low-pressure pump cover 15 of the bearing through-hole 24, an inner rotor-side bearing through-hole 42 (second pump rotor-side bearing through-hole/low-pressure pump rotor-side corresponding to the bearing through hole) are formed. The inner rotor side bearing through-hole 42 is designed to have a larger diameter than the bearing through-hole 24 and a smaller diameter than the gear pump rotor accommodating portion 22 .

Therefore, the inner-rotor-side bearing through-hole 42 and the small-diameter shaft portion 41 of the inner rotor 38 are "spigot-engaged". "Spigot engagement" means "a nested structure in which two parts fit together, one of which has a concave shape and the other has a convex shape". In this way, the vicinity of the end portion of the drive shaft 16 on the low-pressure pump cover 15 side is supported by the inner rotor side bearing through hole 42 by the small diameter shaft portion 41 of the inner rotor 38 , so that the drive shaft 16 has a Shaking can be suppressed.

Also, the inner rotor 38 is configured to be movable in the axial direction of the drive shaft 16, as shown in FIG. That is, relative movement in the direction of the drive axis of the drive shaft 16 is possible, and relative movement in the rotational direction with respect to the drive shaft 16 is restricted. Specifically, the drive shaft 16 to which the inner rotor 38 is fitted is formed in a shape having a flat surface 43 with a width across flats 43, and the inner rotor 38 can move in the drive shaft direction at this portion.

In FIG. 9, the drive shaft 16 is composed of a cylindrical portion 16C and a width across flat portion 16P. It is configured to be inserted. The fitting hole 44 has a similar shape to the width across flat portion 16P and is designed to be slightly larger than the width across flat portion 16P. The width across flat portion 16</b>P is formed longer than the axial length of the inner rotor 38 to increase the drive area and sufficiently transmit the torque of the drive shaft 16 .

A vane pump rotor 26 is press-fitted to the columnar portion 16C, and the vane pump rotor 26 is configured so as not to move in the axial direction and the rotational direction with respect to the columnar portion 16C. Furthermore, when the vane pump rotor 26 and the columnar portion 16C are serration-coupled, they can be in a more rigid fixed state.

On the other hand, the width across flat portion 16P of the drive shaft 16 is fitted with a fitting hole 44 formed in the inner rotor 38 so as to be axially movable. Therefore, as shown in FIG. 8 , even if the drive shaft 16 moves in the axial direction (leftward or rightward), the inner rotor 38 is not forced to move by the drive shaft 16 . Since the vane pump rotor 26 is press-fitted onto the drive shaft 16 , it is moved together with the drive shaft 16 .

Next, the effects of the tandem oil pump configured as described above will be described with reference to FIG. Description is omitted.

Now, when the drive shaft 16 is rotated by an internal combustion engine or an electric motor, the vane pump rotor 26 press-fitted into the cylindrical portion 16C of the drive shaft 16 and the width across flat portion 16P of the drive shaft 16 can move in the axial direction. The inner rotor 38 fitted to is rotated in synchronization with the rotation of the drive shaft 16 . A pump action is thereby performed.

As the vane pump rotor 26 rotates, the oil is sucked from the high-pressure side suction hole 19 as shown by the broken line arrow (Ohigh), and is further pressurized to a high pressure by the rotation of the vane pump rotor 26, as shown by the broken line arrow (Ohigh). is discharged from the high-pressure side discharge hole 18 (see FIG. 1) as shown in FIG.

Similarly, the rotation of the inner rotor 38 causes the oil to be sucked from the low-pressure side suction hole 17 as indicated by the dashed arrow (Olow), and the rotation of the inner rotor 38 further pressurizes the oil to a low pressure (atmospheric pressure or negative pressure). ) and is discharged from the low-pressure side discharge hole 20 as indicated by the dashed arrow (Olow).

In this way, when the drive shaft 16 moves in the axial direction (moves in the thrust direction) while the tandem oil pump is operating, the drive shaft 16 is firmly press-fitted into the vane pump rotor 26. Therefore, the side surface perpendicular to the axial direction of the vane pump rotor 26 comes into contact with the inner end surface of the high-pressure pump cover 13 or the end surface of the partition wall 23 on the vane pump rotor 26 side.

The side surface of the vane pump rotor 26 perpendicular to the axial direction slides while rotating on the inner end surface of the high-pressure pump cover 13 or the end surface of the partition wall 23 on the vane pump rotor 26 side. For this reason, there is a possibility that a seizing phenomenon or an abrasion phenomenon may occur at this sliding portion. However, since the oil discharge pressure of the vane pump rotor 26 is high, the side surface of the vane pump rotor 26 is in contact with the inner end surface of the high-pressure pump cover 13 or the end surface of the partition wall 23 on the vane pump rotor 26 side with a large surface pressure. Also, a sufficient amount of oil can be supplied to the side surface of the vane pump rotor 26 so that oil film shortage does not occur, and the side surface of the vane pump rotor 26 can be suppressed from seizing or wearing.

On the other hand, when the drive shaft 16 is moved in the axial direction (moved in the thrust direction) while the tandem oil pump is operating, the inner rotor 38 is fitted on the drive shaft 16 so as to be movable in the axial direction. Therefore, the inner rotor 38 is free in the axial direction of the drive shaft 16 even if the drive shaft 16 moves. Therefore, the side surface of the inner rotor 38 perpendicular to the axial direction does not contact the inner end surface of the low-pressure pump cover 15 or the inner rotor 38 side end surface of the partition wall 23 with a large surface pressure.

The side surface of the inner rotor 38 orthogonal to the axial direction slides while rotating on the inner end surface of the low-pressure pump cover 15 or the end surface of the partition wall 23 on the inner rotor 38 side. However, the side surface perpendicular to the axial direction of the inner rotor 38 does not contact the inner end surface of the low-pressure pump cover 15 or the inner rotor 38 side end surface of the partition wall 23 with a large surface pressure. The reason is that the inner rotor 38 is free in the axial direction of the drive shaft 16 .

Therefore, even if the oil discharge pressure of the inner rotor 38 is low, the side surface of the inner rotor 38 contacts the inner end surface of the low-pressure pump cover 15 or the inner rotor 38 side end surface of the partition wall 23 with a large surface pressure. Therefore, it is possible to supply a sufficient amount of oil to the side surface of the inner rotor 38 without running out of the oil film, thereby suppressing the seizure phenomenon or wear phenomenon on the side surface of the inner rotor 38. can.

As described above, in this embodiment, since the inner rotor 38 constituting the low-pressure oil pump can move in the axial direction of the drive shaft 16, it is possible to sufficiently supply oil to the side surfaces of the inner rotor 38 even when the discharge pressure is low. Therefore, it is possible to suppress the occurrence of seizure phenomenon or wear phenomenon on the side surface of the inner rotor 38 .

Further, since the vane pump rotor 26 constituting the high-pressure oil pump has a high discharge pressure, even if the side surface of the vane pump rotor 26 comes into contact with the sliding surface with a large surface pressure, the oil is sufficiently supplied to the side surface of the vane pump rotor. It is possible to suppress the occurrence of seizure phenomenon or wear phenomenon on the side surface of the vane pump rotor 26 .

Next, a modified example of this embodiment will be described with reference to FIG. In this modification, the width across flat portion 16P of the drive shaft 16 is changed to a spline. Note that the same reference numerals as those in FIG. 10 indicate the same component parts, and redundant description will be omitted.

In FIG. 11, a spline portion (male spline portion) 16S is formed on the tip side of the drive shaft 16. As shown in FIG. The spline portion 16S is formed longer than the axial length of the inner rotor 38 so that the torque of the drive shaft 16 can be sufficiently transmitted.

The spline portion 16S is formed with spline teeth 45 having a gear-shaped cross section perpendicular to the axial direction. Needless to say, the inner rotor 38 is also formed with an insertion hole (female spline portion) having a similar shape to the spline teeth 45 and having internal teeth that engage with the spline teeth 45 .

Since the spline portion 16S and the inner rotor 38 are spline-coupled in this way, the inner rotor 38 can be rotated by the rotation of the drive shaft 16 and can be moved in the axial direction of the drive shaft 16 . Such a spline connection can also provide the above-described functions and effects.

Next, as a comparative example, a tandem oil pump in which the inner rotor 38 is press-fitted to the drive shaft 16 and the vane pump rotor 26 is configured to be movable in the axial direction of the drive shaft 16 will be described with reference to FIG. .

In FIG. 12, the drive shaft 16 is composed of a cylindrical portion 16C and a width across flat portion 16P. The width across flat portion 16P is inserted into a fitting hole formed in the vane pump rotor 26 with a slight clearance. It is configured to be The fitting hole has a shape similar to that of the width across flat portion 16P, and is designed to be slightly larger than the width across flat portion 16P. An inner rotor 38 is press-fitted to the cylindrical portion 16C, and the inner rotor 38 cannot move in the axial direction and the rotational direction with respect to the cylindrical portion 16C.

When the drive shaft 16 is rotated by an internal combustion engine or an electric motor as in the above-described embodiment, the inner rotor 38 press-fitted into the cylindrical portion 16C of the drive shaft 16 and the width across flat portion 16P of the drive shaft 16 are rotated. A vane pump rotor 26 , which is axially movably fitted, is rotated in synchronization with the rotation of the drive shaft 16 . A pump action is thereby performed.

The rotation of the vane pump rotor 26 causes the oil to be sucked in through the high-pressure side suction hole 19, further pressurized to a high pressure by the rotation of the vane pump rotor 26, and discharged from the high-pressure side discharge hole 18 (see FIG. 1). Similarly, the rotation of the inner rotor 38 causes the oil to be sucked from the low-pressure side suction hole 17 , further pressurized to a low pressure by the rotation of the inner rotor 38 , and discharged from the low-pressure side discharge hole 20 .

When the drive shaft 16 is moved in the axial direction (moved in the thrust direction), the vane pump rotor 26 is fitted in the drive shaft 16 so as to be movable in the axial direction. The rotor 26 is free in the axial direction of the drive shaft 16 . Therefore, the side surface perpendicular to the axial direction of the vane pump rotor 26 does not contact the inner end surface of the high-pressure pump cover 13 or the end surface of the partition wall 23 on the vane pump rotor 26 side with a large surface pressure.

The side surface of the vane pump rotor 26 perpendicular to the axial direction slides while rotating on the inner end surface of the high-pressure pump cover 13 or the end surface of the partition wall 23 on the vane pump rotor 26 side. However, the side surface perpendicular to the axial direction of the vane pump rotor 26 does not contact the inner end surface of the high-pressure pump cover 13 or the end surface of the partition wall 23 on the vane pump rotor 26 side with a large surface pressure.

Therefore, the oil discharge pressure of the vane pump rotor 26 is high, and the side surface of the vane pump rotor 26 contacts the inner end surface of the high-pressure pump cover 13 or the end surface of the partition wall 23 on the vane pump rotor 26 side with a large surface pressure. Therefore, sufficient oil can be supplied to the side surface of the vane pump rotor 26, and the side surface of the vane pump rotor 26 can be prevented from being seized or worn.

On the other hand, when the drive shaft 16 is moved in the axial direction (moved in the thrust direction), the side surface of the inner rotor 38 perpendicular to the axial direction is It comes into contact with the inner end face of the low-pressure pump cover 15 or the end face of the partition wall 23 on the inner rotor 38 side with a large surface pressure.

The side surface of the inner rotor 38 orthogonal to the axial direction slides while rotating on the inner end surface of the low-pressure pump cover 15 or the end surface of the partition wall 23 on the inner rotor 38 side. For this reason, there is a possibility that a seizing phenomenon or an abrasion phenomenon may occur at this sliding portion.

That is, when the side surface of the inner rotor 38 contacts the inner end surface of the low-pressure pump cover 15 or the inner rotor 38 side end surface of the partition wall 23 with a large surface pressure, the oil discharge pressure is low. Since a sufficient amount of oil cannot be supplied to the side surface of the inner rotor 38, the side surface of the inner rotor 38 may be seized or worn.

Thus, in the comparative example, there is a possibility that the pump rotor of the low-pressure pump is seized or worn, but in the present embodiment, the pump rotor of the low-pressure pump is seized or worn. Fear can be controlled. In addition, in this embodiment, the arrangement positions of the high-pressure pump and the low-pressure pump can be reversed. Even in this case, the above configuration remains the same.

As described above, according to the present invention, in a tandem-type oil pump that combines a high-pressure oil pump and a low-pressure oil pump, the pump rotor of the low-pressure oil pump can move in the axial direction of the drive shaft. A sufficient amount of oil can be supplied to the side surface of the low-pressure oil pump, and it is possible to suppress the seizure phenomenon or wear phenomenon on the side surface of the pump rotor of the low-pressure oil pump.

Also, since the high-pressure oil pump has a high discharge pressure, even if the side surface of the pump rotor of the high-pressure oil pump abuts against the pump storage section with a large surface pressure, a sufficient amount of oil is applied to the side surface of the pump rotor of the high-pressure oil pump. Oil can be supplied, and seizure phenomenon or wear phenomenon can be suppressed on the side surface of the pump rotor of the high-pressure oil pump.

It should be noted that the present invention is not limited to the several embodiments described above, and includes various modifications. The above embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the described configurations. Moreover, it is possible to replace a part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. Other configurations can be added, deleted, or replaced with respect to the configuration of each embodiment.

Claims

a first pump rotor accommodating portion and a second pump rotor accommodating portion; a partition wall partitioning the first pump rotor accommodating portion and the second pump rotor accommodating portion; and the first pump formed in the partition wall. a pump body having a bearing through hole connecting between the rotor accommodating portion and the second pump rotor accommodating portion;
a drive shaft rotatably arranged in the bearing through hole and driven to rotate by an external power source;
A first pump rotor disposed in the first pump rotor accommodating portion and fixed relative to the drive shaft in a direction of the drive axis and a direction of rotation thereof, wherein the first pump rotor is the drive shaft. a first oil pump that is rotationally driven by the shaft to pressurize the oil introduced from the first suction portion and discharge it from the first discharge portion;
A second rotor that is disposed in the second pump rotor accommodating portion, is movable relative to the drive shaft in the drive axis direction, and is restricted from moving relative to the drive shaft in the rotational direction. A pump rotor is provided, and the second pump rotor is rotationally driven by the drive shaft so that the oil introduced from the second suction portion is reduced by the pressure discharged from the first discharge portion of the first oil pump. a second oil pump that discharges from the second discharge portion at a lower pressure than the second oil pump.
In the tandem type oil pump according to claim 1,
The drive shaft has a fixed portion,
The first pump rotor is press-fitted and fixed to a fixed portion of the drive shaft,
The drive shaft has a pair of width across flats parts,
The second pump rotor is provided with a pair of width across flats fitting portions that mesh with the pair of width across flats portions, and is movably fitted to the pair of width across flats portions. Tandem type oil pump.
In the tandem type oil pump according to claim 1,
The drive shaft has a fixed portion,
The first pump rotor is press-fitted and fixed to a fixed portion of the drive shaft,
The drive shaft has a male spline portion provided in the direction in which the drive shaft extends,
The tandem-type oil pump, wherein the second pump rotor includes a female spline portion that meshes with the male spline portion, and is movably fitted to the male spline portion.
In the tandem oil pump according to claim 2,
A tandem type oil pump, wherein the axial length of the width across flat portion formed on the drive shaft is longer than the axial length of the second pump rotor.
In the tandem type oil pump according to claim 3,
A tandem-type oil pump, wherein the axial length of the male spline portion formed on the drive shaft is longer than the axial length of the second pump rotor.
In the tandem type oil pump according to claim 1,
The pump body is provided between the second pump rotor accommodating portion and the bearing through hole, and has a diameter larger than that of the bearing through hole and smaller than that of the second pump rotor accommodating portion. a second pump rotor side bearing through hole formed continuously with the second pump rotor accommodating portion;
The second pump rotor is formed with a second pump rotor diameter small shaft portion integrally formed with the second pump rotor, and the second pump rotor diameter small shaft portion is a through hole for the second pump rotor side bearing. A tandem-type oil pump characterized by being housed in a hole and bearing.
In the tandem type oil pump according to claim 1,
Attached to the pump body are a first pump cover that closes the first pump rotor accommodating portion, and a second pump cover that is provided on the opposite side of the first pump cover and closes the second pump rotor accommodating portion. be
The first pump rotor is arranged between the first pump cover and the partition wall and fixed to the drive shaft,
The second pump rotor is arranged between the second pump cover and the partition wall, and is fitted to the drive shaft so as to be able to move relative to the drive shaft. tandem type oil pump.
In the tandem type oil pump according to claim 7,
The first pump cover and the second pump cover are attached to the pump body along a plane perpendicular to the axis of the drive shaft,
The first pump cover is provided with a first discharge hole that opens at a radial position with respect to the drive shaft and is connected to the first discharge portion,
A first suction hole, which opens at a radial position with respect to the drive shaft and communicates with the first suction portion, is provided on the side of the pump body on which the second pump cover is provided. Tandem type oil pump.
In the tandem oil pump according to claim 8,
a pair of mounting portions which are provided on the pump body so as to sandwich the pump body at positions in a radial direction with respect to the drive shaft and which are mounted on an internal combustion engine;
A tandem-type oil pump, wherein at least one of the mounting portions is provided with a second suction hole communicating with the second suction portion of the second oil pump.
In the tandem type oil pump according to claim 1,
The first oil pump is
an adjustment ring arranged swingably in the first pump rotor accommodation portion and having a rotor accommodation portion provided therein; a pump rotor accommodated inside the adjustment ring; an outer peripheral surface of the pump rotor; a plurality of vanes forming a plurality of hydraulic fluid chambers through which oil is guided between the adjustment ring and the pump rotor, wherein the volumes of the plurality of hydraulic fluid chambers increase as the drive shaft rotates. Oil is sucked from the first suction portion that opens to the hydraulic oil chamber that is open to the hydraulic oil chamber, and the first discharge opens to the hydraulic oil chamber that decreases in volume among the plurality of hydraulic oil chambers as the drive shaft rotates. A tandem-type oil pump characterized by being a vane-type oil pump that discharges oil from a part.
In the tandem oil pump according to claim 10,
The second oil pump is
As the second pump rotor accommodated in the second pump rotor accommodation portion, an outer rotor including a plurality of internal teeth on the inner peripheral side, and an outer rotor accommodated inside the outer rotor and along the drive axis of the drive shaft A tandem-type oil pump characterized by being a gear-type oil pump provided movably in the direction of and having a plurality of external teeth meshing with the plurality of internal teeth on an outer peripheral side.
In the tandem type oil pump according to claim 1,
The first oil pump is a variable capacity oil feed pump that supplies pressurized oil to at least a main oil gallery of the internal combustion engine,
A tandem oil pump, wherein the second oil pump is a scavenging oil pump that collects oil from an oil pan of an internal combustion engine.
a high-pressure pump rotor housing portion and a low-pressure pump rotor housing portion; a partition wall that separates the high-pressure pump rotor housing portion and the low-pressure pump rotor housing portion; a pump body having a bearing through-hole connecting with the low-pressure pump rotor accommodating portion;
a drive shaft rotatably arranged in the bearing through hole and driven to rotate by an external power source;
A high-pressure pump rotor disposed in the high-pressure pump rotor accommodating portion and press-fitted to the drive shaft is provided, and the high-pressure pump rotor is rotationally driven by the drive shaft to act as a pump at a first discharge pressure. a high-pressure oil pump that performs
It has a low-pressure pump rotor disposed in the low-pressure pump rotor accommodating portion and mounted movably in the drive axis direction with respect to the drive shaft. and a low-pressure oil pump that performs a pumping action at a second discharge pressure lower than the first discharge pressure.
A tandem oil pump according to claim 13,
The high-pressure oil pump is a variable displacement oil feed pump that supplies pressurized oil to at least a main oil gallery of the internal combustion engine,
A tandem-type oil pump, wherein the low-pressure oil pump is a scavenging oil pump that collects oil from an oil pan of the internal combustion engine.
A tandem oil pump according to claim 14,
the variable displacement oil feed pump is a vane oil pump,
A tandem-type oil pump, wherein the scavenging oil pump is a gear-type oil pump.
A tandem oil pump according to claim 13,
The low-pressure pump is provided in the pump body between the low-pressure pump rotor accommodating portion and the bearing through-hole, and has a diameter larger than that of the bearing through-hole and smaller than that of the low-pressure pump rotor accommodating portion. a low-pressure pump rotor-side bearing through-hole formed continuously with the rotor accommodating portion,
The low-pressure pump rotor is formed with a low-pressure pump rotor diameter small shaft portion integrally formed with the low-pressure pump rotor, and the low-pressure pump rotor diameter small shaft portion is accommodated in the low-pressure pump rotor side bearing through hole. A tandem type oil pump characterized by bearings.
A tandem oil pump according to claim 16,
The drive shaft has a cylindrical portion and a spline portion or a width across flat portion,
The high-pressure pump rotor is press-fitted and fixed to the cylindrical portion,
In the spline portion or the width across flat portion, the low-pressure pump rotor provided with a fitting hole having a similar shape to the spline portion or the width across flat portion extends in the axial direction with respect to the drive shaft. A tandem-type oil pump, characterized by being movably fitted.
A tandem oil pump according to claim 17,
A tandem oil pump, wherein the axial length of the spline portion or the width across flat portion is longer than the axial length of the low-pressure pump rotor.