JP7554133B2 - Tandem Oil Pump - Google Patents

Description

The present invention relates to an oil pump, and in particular to a tandem oil pump equipped with two oil pumps.

Tandem oil pumps applied to internal combustion engines mounted on automobiles have a well-known configuration, as shown, for example, in JP 2008-163925 A (Patent Document 1).

The tandem oil pump shown in Patent Document 1 has a pump body formed into a cylindrical shape with a bottom, in which a first pump of the same shape and a second pump arranged with a shifted rotational phase with respect to the first pump are arranged, and is equipped with an annular partition member for separating the pumps, and a drive shaft that is slidably supported within the pump body and passes through both pumps and the partition member to transmit driving force to the inner rotors of both pumps, and each pump performs a pumping action by rotating the drive shaft due to the driving force transmitted from the internal combustion engine. Note that the first pump and the second pump have substantially the same discharge pressure.

Separately, a tandem oil pump has also been proposed that combines a high-pressure oil pump with a low-pressure oil pump. For example, a tandem oil pump is known that combines a scavenging oil pump (low-pressure oil pump) that recovers engine oil (hereinafter simply referred to as oil) from the oil pan with a variable displacement oil feed pump (high-pressure oil pump) that supplies pressurized oil to the variable valve mechanism and the main oil gallery of the internal combustion engine. Note that the scavenging oil pump is, for example, a gear-type oil pump, and the variable displacement oil feed pump is a vane-type oil pump.

A scavenging oil pump is a pump that simultaneously sucks oil, mist, blow-by gas, etc. from inside the oil pan. In addition, the oil containing the sucked-in air bubbles and foreign matter is separated in a reservoir tank or centrifugal separator, and is 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.

The present invention is directed to a tandem oil pump that combines a high-pressure oil pump and a low-pressure oil pump, but the high-pressure oil pump and the low-pressure oil pump are not limited to the above-mentioned scavenging pump or variable displacement oil feed pump.

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 configured to be rotated by power from a rotary drive source such as an internal combustion engine or an electric motor. It is necessary to provide a thrust restriction 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 drive shaft are firmly fixed, and the side of the pump rotor perpendicular to the axis of the drive shaft is brought into contact with the wall of the pump rotor storage section, preventing the drive shaft to which the pump rotor is attached from moving in the axial direction. In this case, the side of the pump rotor rotates while sliding against the wall of the pump rotor storage section that houses the pump rotor.

However, if the pump rotor of the low-pressure oil pump is fixed to the drive shaft, and the wall of the pump rotor housing section and the side of the pump rotor of the low-pressure oil pump come into contact with strong surface pressure, the discharge pressure of the low-pressure oil pump is low, making it difficult to supply sufficient oil to the contact area between the side of the pump rotor and the wall of the pump rotor housing section, causing the oil film to break, and there is a risk of the contact area becoming seized or wearing out rapidly.

The object of the present invention is to provide a new tandem oil pump that can suppress the occurrence of seizure or wear on the side of the pump rotor of the low-pressure oil pump when a high-pressure oil pump and a low-pressure oil pump are combined.

The present invention relates to
a pump body including a first pump rotor accommodating portion, a second pump rotor accommodating portion, a partition wall separating the first pump rotor accommodating portion from the second pump rotor accommodating portion, and a bearing through hole formed in the partition wall connecting the first pump rotor accommodating portion and the second pump rotor accommodating portion;
a drive shaft rotatably disposed in the bearing through hole and rotated by an external power source;
a first oil pump having a first pump rotor disposed in a first pump rotor accommodating portion and fixed to the drive shaft so as to be restricted in relative movement in a drive axial direction and a rotational direction, the first pump rotor being rotationally driven by the drive shaft to pressurize oil introduced from a first suction portion and discharge the oil from a first discharge portion;
and a second oil pump having a second pump rotor disposed in a second pump rotor accommodating portion, capable of moving relative to the drive shaft in the direction of the drive axis but restricted in its movement in the rotational direction relative to the drive shaft, the second pump rotor being rotationally driven by the drive shaft to discharge oil guided from the second suction portion from the second discharge portion at a pressure lower than the pressure discharged from the first pump.

The present invention also provides a method for producing a method for manufacturing a semiconductor device comprising the steps of:
a pump body including a high-pressure pump rotor accommodating section, a low-pressure pump rotor accommodating section, a partition wall separating the high-pressure pump rotor accommodating section from the low-pressure pump rotor accommodating section, and a drive shaft bearing portion formed on the partition wall and connecting between the high-pressure pump rotor accommodating section and the low-pressure pump rotor accommodating section;
a drive shaft that is disposed in the high-pressure pump rotor housing and the low-pressure pump rotor housing, and is rotatably supported by the drive shaft bearing and is driven to rotate by an external power source;
a high-pressure oil pump that is disposed in a high-pressure pump rotor accommodating portion, has a high-pressure pump rotor that is press-fitted and fixed to a drive shaft, and performs a pumping action at a first discharge pressure as the high-pressure pump rotor is rotationally driven by the drive shaft;
and a low-pressure oil pump which has a low-pressure pump rotor disposed in a low-pressure pump rotor accommodating portion and attached so as to be movable in the drive axis direction relative to the drive shaft, and which performs pumping action at a second discharge pressure lower than the first discharge pressure as the low-pressure pump rotor is rotationally driven by the drive shaft.

According to the present invention, in a tandem 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, so that a sufficient amount of oil can be supplied to the side of the second pump rotor (low-pressure pump rotor) of the second oil pump (low-pressure oil pump), and the occurrence of seizure or wear on the side of the second pump rotor (low-pressure pump rotor) can be suppressed.

In addition, since the high-pressure oil pump has a high discharge pressure, even if the side of the first pump rotor (high-pressure pump rotor) abuts against the pump storage section with a large surface pressure, a sufficient amount of oil can be supplied to the side of the first pump rotor (high-pressure pump rotor) of the first oil pump (high-pressure oil pump), and the occurrence of seizure or wear on the side of the first pump rotor (high-pressure pump rotor) can be suppressed.

1 is an external perspective view of a tandem 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 as viewed from the side of the variable displacement oil feed pump. FIG. 2 is a rear view of the tandem oil pump shown in FIG. 1 as viewed 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. 2 is a cross-sectional view illustrating the internal structure of a pump portion of a variable displacement oil feed pump. FIG. 2 is an exploded perspective view of the scavenging oil pump as viewed obliquely from above. FIG. 2 is a cross-sectional view illustrating the internal structure of a pump portion of a scavenging oil pump. 2 is a cross-sectional view showing the AA section of the tandem oil pump shown in FIG. 1. FIG. 2 is an exploded perspective view for explaining the shapes of an inner rotor and a drive shaft of the scavenging oil pump. FIG. 2 is a perspective view of the tandem oil pump shown in FIG. 1 , with a portion cut away and viewed obliquely from above. FIG. 2 is a partially cutaway external perspective view of a modified example of the tandem oil pump shown in FIG. 1, viewed obliquely from above. FIG. 1 is a perspective view of a tandem oil pump as a comparative example, with a portion cut away and viewed obliquely from above.

The following describes in detail an embodiment of the present invention with reference to the drawings. However, the present invention is not limited to the following embodiment, and the scope of the present invention includes various modifications and applications within the technical concept of the present invention.

Figure 1 shows a tandem oil pump according to an embodiment of the present invention, viewed from diagonally above. The tandem oil pump 10 is a roughly rectangular box-shaped pump body 11, a high-pressure pump cover 13 (corresponding to the first pump cover in the claims) attached to the front portion 11F of the pump body 11 with bolts 12, and a low-pressure pump cover 15 (corresponding to the second pump cover in the claims) attached to the back portion 11B of the pump body 11 with bolts 14 (see Figure 3).

Although details will be explained later, a variable displacement oil feed pump, which is a high-pressure oil pump (corresponding to the first pump in the claims), is housed inside the pump body 11 on the high-pressure pump cover 13 side, and a scavenging oil pump, which is a low-pressure oil pump (corresponding to the second pump in the claims), is housed inside the pump body 11 on the low-pressure pump cover 15 side. Note that here, the pump body 11 is formed in a roughly rectangular box shape, but in reality, the shape is changed to correspond to the external shape and size of the internal combustion engine. However, even if the external shape changes, the basic concept of the present invention remains the same.

The tandem oil pump 10 is equipped with a drive shaft 16 that passes through the high-pressure pump cover 13 and the pump body 11 and extends to the low-pressure pump cover 15. This drive shaft 16 is rotated by an external drive source such as the crankshaft of an internal combustion engine or an electric motor. The drive shaft 16 is shared by the high-pressure oil pump and the low-pressure oil pump, and the drive shaft 16 rotates and drives the pump rotors of the high-pressure oil pump and the low-pressure oil pump, respectively.

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

The upper surface 11U of the pump body 11 is provided with a pair of mounting portions 11A that are attached to the oil pan of the internal combustion engine, and are fixed to the internal combustion engine by inserting fixing bolts into the mounting portions 11A, and a low-pressure side suction hole 17 is formed in the mounting portions 11A. The pair of mounting portions 11A are provided in radial positions relative to the drive shaft 16 provided on the pump body 11, sandwiching the pump body 11 from both sides, and are attached to the internal combustion engine. Therefore, when the tandem oil pump 10 is attached to the internal combustion engine, oil in the oil pan can be easily guided to the low-pressure side suction hole 17.

Figure 2 shows the front of the tandem oil pump 10 on the side where the high-pressure pump cover 13 is provided. This high-pressure pump cover 13 is fixed to the front portion 11F of the pump body 11 and forms part of the hydraulic oil chamber (pump chamber) of the high-pressure oil pump. 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.

The high-pressure pump cover 13, which is located radially outward from the drive shaft center of the drive shaft 16, is provided with a high-pressure side discharge hole (corresponding to the first discharge hole in the claims) 18 connected to the discharge part of the high-pressure oil pump (corresponding to the first discharge part in the claims). In this embodiment, the high-pressure side discharge hole 18 supplies pressurized oil to at least the main oil gallery of the internal combustion engine, but it may also be supplied to the variable valve mechanism.

Figure 3 shows the back of the tandem oil pump 10 on the side where the low-pressure pump cover 15 is provided. This low-pressure pump cover 15 is fixed to the back portion 11B of the pump body 11 to form part of the hydraulic oil chamber of the low-pressure oil pump. 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. In addition, the back portion 11B of the pump body 11 at a radially outer position relative to the drive axis of the drive shaft 16 is formed with a high-pressure side suction hole 19 (corresponding to the first suction hole in the claims) connected to the suction portion of the high-pressure oil pump (corresponding to the first suction portion in the claims).

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

Next, the configuration of the high-pressure oil pump and the low-pressure oil pump will be explained with reference to Figures 4 to 7. Figure 4 shows the disassembled state of the high-pressure oil pump side after the low-pressure oil pump has been installed, and Figure 6 shows the disassembled state of the low-pressure oil pump side after the high-pressure oil pump has been installed. Here, as mentioned above, the high-pressure oil pump is a vane-type oil pump (variable displacement type) that uses vanes, and the low-pressure pump is a gear-type oil pump that uses trochoid gears.

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

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

The structure of the vane-type oil pump will be explained using Figures 4 and 5, but because this vane-type oil pump is a well-known structure, the explanation will be brief. Here, Figure 5 shows the pump portion cross-sectioned in a direction perpendicular to the axis of a well-known vane-type oil pump.

In Figures 4 and 5, the pump body 25 is housed in a concave vane pump rotor housing 21 formed in the pump body 11. A vane pump rotor 26 (corresponding to the first pump rotor/high pressure pump rotor in the claims) is arranged in the vane pump rotor housing 21, which is press-fitted with the drive shaft 16 at approximately the center, and an adjustment ring 27, whose oscillation center is eccentric with the drive shaft 16, is arranged on the outside of the vane pump rotor 26. In this way, the vane pump rotor 26 is press-fitted with the drive shaft 16, and is firmly fixed so that relative movement in the drive axis direction and rotation direction is restricted.

The adjustment ring 27 can swing around the pivot 28 as a fulcrum, and in the initial state, the adjustment ring 27 is pushed to the right in FIG. 5 by the preload of the arm portion 29 and the control spring 30 arranged in the vane pump rotor housing portion 21, and the eccentricity is set to the maximum.

Vanes 31 are arranged in multiple slits provided in the vane pump rotor 26, and when the vane pump rotor 26 rotates, their tips slide along the inner circumferential surface of the adjustment ring 27 while protruding from the outer circumferential surface of the vane pump rotor 26. Even when the vane pump rotor 26 is stopped, all of the vanes 31 are supported by the vane ring 32 so that they do not recede inward.

The volume of the space (hereinafter referred to as the hydraulic oil chamber) 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 increases and decreases as the vane pump rotor 26 rotates counterclockwise as shown in FIG. 5. In the range where the volume of the hydraulic oil chamber increases, an intake section 33 is provided on the side of the pump body 11. This intake section 33 is connected to the high-pressure side intake hole 19 provided on the back surface portion 11B of the pump body 11 on the low-pressure oil pump side.

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

The vane-type oil pump performs a pumping action by sucking up oil through the intake hole 19 and discharging the oil through the discharge hole 18 to the variable valve mechanism or the main oil gallery of the internal combustion engine. The compression spring 35 biases the ball valve 36, and is configured so that when the discharge pressure rises above a predetermined value, the ball valve 36 opens to reduce the discharge pressure. The configuration and operation of this vane-type oil pump are well known, so further explanation will be omitted.

In this way, the vane type oil pump has an adjustment ring 27 that is arranged to be able to swing in the vane pump rotor housing 21 and has a vane housing section provided inside, a vane pump rotor 26 that is housed inside the adjustment ring 27 and fixed to the drive shaft 16, and a plurality of vanes 31 that are housed on the outer surface of the vane pump rotor 26 and form a plurality of hydraulic oil chambers to which oil is guided between the adjustment ring 27 and the vane pump rotor 26.The vane type oil pump is an oil pump that draws oil from the suction hole 19 (see Figure 3), which is one of the multiple hydraulic oil chambers whose volume increases as the drive shaft 16 rotates, and discharges oil from the discharge hole 18 (see Figure 2), which is one of the multiple hydraulic oil chambers whose volume decreases as the drive shaft 16 rotates.

Next, the configuration of the gear-type oil pump will be explained using Figures 6 and 7, but as this gear-type oil pump is also well known, the explanation will be brief. Here, Figure 7 shows the pump portion cross-sectioned in a direction perpendicular to the axis of a well-known gear-type oil pump.

In FIG. 6, a gear pump rotor storage section 22 is formed on the rear portion 11B side 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 arranged in this section so as to be able to slide and rotate freely.

Furthermore, an inner rotor 38 (corresponding to a part of the second pump rotor/low-pressure pump rotor in the claims) is disposed inside the outer rotor 37. 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 periphery of the outer rotor 37, and these internal teeth 40 mesh with the external teeth 39 of the inner rotor 38.

Multiple hydraulic oil chambers are formed between the external teeth 39 of the inner rotor 38 and the internal teeth 40 of the outer rotor 37. As the inner rotor 38 rotates, the outer rotor 37 rotates eccentrically, increasing and decreasing the volume of the hydraulic oil chambers, thereby continuously sucking in and discharging oil to perform a pumping action.

The inner rotor 38 is rotated by the drive shaft 16, but in this embodiment, the inner rotor 38 can move relative to the drive shaft 16 in the direction of the drive axis, and its relative movement in the rotational direction relative to the drive shaft 16 is restricted. Specifically, the drive shaft 16 into which the inner rotor 38 fits is formed in a shape that has a two-face width, and the inner rotor 38 can move in this portion in the drive shaft direction.

Here, the two-face width refers to a shape formed along the axial direction of the drive shaft 16, with opposing surfaces being parallel planes. Therefore, the inner rotor 38 can move along the axial direction of the drive shaft 16, and can rotate integrally with the drive shaft 16 in the rotational direction.

In this way, the gear-type oil pump is an oil pump that has an outer rotor 37 that is housed inside the gear pump rotor housing 22 and includes multiple internal teeth 40 on its inner circumference, and an inner rotor that is housed inside the outer rotor 37 and is movably mounted on the drive shaft 16 in the direction of the drive axis of the drive shaft 16 and includes multiple external teeth 39 that mesh with the multiple internal teeth 40 on its outer circumference.

Next, the internal structure of the tandem oil pump 10 shown in FIG. 1 will be explained using FIG. 8, which is a cross section taken along the line A-A in FIG. 1.

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 back portion 11B of the pump body 11. A vane-type oil pump, which is a high-pressure oil pump, is housed inside the pump body 11 on the side of the high-pressure pump cover 13, and a gear-type oil pump, which is a low-pressure oil pump, is housed inside the pump body 11 on the side of the low-pressure pump cover 15.

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

The drive shaft 16 is formed with a large diameter section 16L having a circular cross section, and this large diameter section 16L is supported in a hole formed in the high-pressure pump cover 13. The drive shaft 16 is also supported in 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 against the low-pressure pump cover 15 or extends to the point where it abuts, and this portion is not supported. Therefore, the drive shaft 16 vibrates near the low-pressure pump cover 15. When the drive shaft 16 touches the low-pressure pump cover 15, the relative positions of the inner rotor 38 and outer rotor 37 change, which can cause abnormal noise or oil leakage from the hydraulic oil chamber.

For this reason, in this embodiment, a small diameter shaft portion (corresponding to the second pump rotor small diameter shaft portion/low pressure pump rotor small diameter shaft portion in the claims) 41 is integrally formed on the opposite side of the inner rotor 38 from the low pressure pump cover 15, and extends from the inner rotor 38 toward the vane pump rotor 26. The cross section of this small diameter shaft portion 41 perpendicular to the axis of the drive shaft 16 is formed in a circular shape.

In addition, an inner rotor side bearing through hole (corresponding to the second pump rotor side bearing through hole/low pressure pump rotor side bearing through hole in the claims) 42 that supports the small diameter shaft portion 41 is formed on the low pressure pump cover 15 side of the bearing through hole 24. This 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 housing 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-fitted." "Spigot-fitted" means "a nested structure where one part is concave and the other is convex at the part where the two parts fit together." In this way, the end of the drive shaft 16 near the low-pressure pump cover 15 side is supported by the small diameter shaft portion 41 of the inner rotor 38 in the inner rotor side bearing through hole 42, which suppresses runout of the drive shaft 16.

As shown in FIG. 9, the inner rotor 38 is configured to be movable in the axial direction of the drive shaft 16. In other words, it is capable of relative movement in the direction of the drive axis of the drive shaft 16, but is restricted from moving relative to the drive shaft 16 in the rotational direction. Specifically, the drive shaft 16 into which the inner rotor 38 fits is formed in a shape that has a two-sided flat surface 43, and the inner rotor 38 can move in this portion in the axial direction.

In FIG. 9, the drive shaft 16 is composed of a cylindrical portion 16C and a two-face width portion 16P, and the two-face width portion 16P is configured to be inserted into a fitting hole 44 formed in the inner rotor 38 with a small gap between them. The fitting hole 44 has a similar shape to the two-face width portion 16P and is designed to be slightly larger than the dimensions of the two-face width portion 16P. The two-face width portion 16P is formed to be longer than the axial length of the inner rotor 38, and the driving area is increased to allow the torque of the drive shaft 16 to be transmitted sufficiently.

The vane pump rotor 26 is press-fitted into the cylindrical portion 16C, and the vane pump rotor 26 cannot move axially or rotationally relative to the cylindrical portion 16C. If the vane pump rotor 26 and the cylindrical portion 16C are connected by serrations, they can be fixed even more firmly.

Meanwhile, the fitting hole 44 formed in the inner rotor 38 is fitted into the two-face width portion 16P of the drive shaft 16 so as to be movable in the axial direction. Therefore, as shown in FIG. 8, even if the drive shaft 16 moves in the axial direction (left or right), the inner rotor 38 is not forcibly moved by the drive shaft 16. Furthermore, since the vane pump rotor 26 is press-fitted and fixed to the drive shaft 16, it moves together with the drive shaft 16.

Next, the effect of the tandem oil pump configured in this way will be explained using Figure 10, but because the operation of vane-type oil pumps and gear-type oil pumps is well known, explanations of these will be 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 inner rotor 38 axially movably fitted into the two-face width portion 16P of the drive shaft 16 rotate in synchronization with the rotation of the drive shaft 16. This performs the pumping action.

Then, as the vane pump rotor 26 rotates, the oil is sucked in through the high-pressure side suction hole 19 as shown by the dashed arrow (Ohigh), and is then pressurized to a high pressure by the rotation of the vane pump rotor 26, and is discharged from the high-pressure side discharge hole 18 (see Figure 1) as shown by the dashed arrow (Ohigh).

Similarly, as the inner rotor 38 rotates, oil is sucked in through the low-pressure side suction hole 17 as shown by the dashed arrow (Olow), and is then pressurized to a low pressure (atmospheric pressure or negative pressure in some cases) as the inner rotor 38 rotates, and is then discharged from the low-pressure side discharge hole 20 as shown by the dashed arrow (Olow).

In this way, when the tandem oil pump is operating and the drive shaft 16 moves axially (in the thrust direction), the drive shaft 16 is firmly press-fitted into the vane pump rotor 26, so that the side of the vane pump rotor 26 perpendicular to the axial direction comes into contact with the inner end face of the high-pressure pump cover 13 or the end face 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 rotates and slides against 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. This may cause seizure or wear at this sliding portion. However, because the oil discharge pressure by the vane pump rotor 26 is high, even if the side surface of the vane pump rotor 26 abuts against 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, a sufficient amount of oil can be supplied to the side surface of the vane pump rotor 26, so that the oil film does not break, and the occurrence of seizure or wear on the side surface of the vane pump rotor 26 can be suppressed.

On the other hand, when the tandem oil pump is operating and axial movement (movement in the thrust direction) occurs on the drive shaft 16, the inner rotor 38 is fitted to the drive shaft 16 so as to be movable in the axial direction, so that the inner rotor 38 is free to move 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 come 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 perpendicular to the axial direction rotates and slides against 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. However, the side surface of the inner rotor 38 perpendicular to the axial direction does not abut with a large surface pressure against 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. This is because the inner rotor 38 is free in the axial direction of the drive shaft 16.

As a result, even if the oil discharge pressure from the inner rotor 38 is low, the side of the inner rotor 38 does not come 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, so a sufficient amount of oil can be supplied to the side of the inner rotor 38, preventing the oil film from breaking and suppressing the occurrence of seizure or wear on the side of the inner rotor 38.

In this way, in this embodiment, the inner rotor 38 that constitutes the low-pressure oil pump can move in the axial direction of the drive shaft 16, so that even if the discharge pressure is low, sufficient oil can be supplied to the side of the inner rotor 38, and the occurrence of seizure or wear on the side of the inner rotor 38 can be suppressed.

In addition, the vane pump rotor 26 that constitutes the high-pressure oil pump has a high discharge pressure, so even if the side of the vane pump rotor 26 abuts against the sliding surface with a large surface pressure, sufficient oil can be supplied to the side of the vane pump rotor, and the occurrence of seizure or wear on the side of the vane pump rotor 26 can be suppressed.

Next, a modified version of this embodiment will be described with reference to FIG. 11. In this modified version, the two-face width portion 16P of the drive shaft 16 is changed to a spline. Note that the same reference numbers as in FIG. 10 indicate the same components, so duplicated descriptions will be omitted.

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

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

In this way, the spline portion 16S and the inner rotor 38 are spline-coupled, so that the inner rotor 38 is rotated by the rotation of the drive shaft 16 and can move in the axial direction of the drive shaft 16. This type of spline coupling can also achieve the above-mentioned functions and effects.

Next, as a comparative example, a tandem oil pump in which the inner rotor 38 is press-fitted onto the drive shaft 16 and the vane pump rotor 26 is movable in the axial direction of the drive shaft 16 will be described with reference to FIG. 12.

In FIG. 12, the drive shaft 16 is composed of a cylindrical portion 16C and a two-face width portion 16P, and the two-face width portion 16P is configured to be inserted with a small gap into a fitting hole formed in the vane pump rotor 26. The fitting hole has a similar shape to the two-face width portion 16P and is designed to be slightly larger than the dimensions of the two-face width portion 16P. The inner rotor 38 is press-fitted into the cylindrical portion 16C, and the inner rotor 38 cannot move axially or rotationally relative to the cylindrical portion 16C.

As in the above-described embodiment, when the drive shaft 16 is rotated by an internal combustion engine or an electric motor, the inner rotor 38 press-fitted into the cylindrical portion 16C of the drive shaft 16 and the vane pump rotor 26 axially movably fitted into the two-face width portion 16P of the drive shaft 16 rotate in synchronization with the rotation of the drive shaft 16. This performs the pumping action.

Then, the rotation of the vane pump rotor 26 draws oil into the high-pressure side suction hole 19, and the rotation of the vane pump rotor 26 pressurizes the oil to a high pressure before discharging it from the high-pressure side discharge hole 18 (see Figure 1). Similarly, the rotation of the inner rotor 38 draws oil into the low-pressure side suction hole 17, and the rotation of the inner rotor 38 pressurizes the oil to a low pressure before discharging it from the low-pressure side discharge hole 20.

When the drive shaft 16 moves in the axial direction (movement in the thrust direction), the vane pump rotor 26 is fitted to the drive shaft 16 so that it can move in the axial direction, so even if the drive shaft 16 moves, the vane pump rotor 26 is free in the axial direction of the drive shaft 16. Therefore, the side surface of the vane pump rotor 26 perpendicular to the axial direction does not come 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 with a large surface pressure.

The side surface of the vane pump rotor 26 perpendicular to the axial direction rotates and slides against 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 of the vane pump rotor 26 perpendicular to the axial direction does not abut with a large surface pressure against 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.

As a result, the oil discharge pressure by the vane pump rotor 26 is high, and the side of the vane pump rotor 26 does not come into contact with the inner end face of the high-pressure pump cover 13 or the end face of the partition wall 23 on the vane pump rotor 26 side with a large surface pressure, so sufficient oil can be supplied to the side of the vane pump rotor 26, and the occurrence of seizure or wear on the side of the vane pump rotor 26 can be suppressed.

On the other hand, when the drive shaft 16 moves in the axial direction (movement in the thrust direction), the drive shaft 16 is firmly press-fitted into the inner rotor 38, so that the side of the inner rotor 38 perpendicular to the axial direction 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 great surface pressure.

The side surface of the inner rotor 38 that is perpendicular to the axial direction rotates and slides against 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. This may cause seizure or wear at this sliding portion.

In other words, when the side of the inner rotor 38 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 side of the inner rotor 38 with a large surface pressure, the oil discharge pressure is low, so a sufficient amount of oil cannot be supplied to the side of the inner rotor 38, and there is a risk of the side of the inner rotor 38 becoming seized or worn.

Thus, in the comparative example, there is a risk of the pump rotor of the low-pressure pump becoming seized or worn, but in this embodiment, the risk of the pump rotor of the low-pressure pump becoming seized or worn can be suppressed. Note that in this embodiment, the positions of the high-pressure pump and the low-pressure pump can also be reversed. Even in this case, the above-mentioned configuration remains unchanged.

As described above, according to the present invention, in a tandem 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, so that a sufficient amount of oil can be supplied to the side of the pump rotor of the low-pressure oil pump, and the occurrence of seizure or wear on the side of the pump rotor of the low-pressure oil pump can be suppressed.

In addition, because the high-pressure oil pump has a high discharge pressure, even if the side 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 can be supplied to the side of the pump rotor of the high-pressure oil pump, and the occurrence of seizure or wear on the side of the pump rotor of the high-pressure oil pump can be suppressed.

The present invention is not limited to the above-mentioned embodiments, but includes various modified examples. The above-mentioned embodiments have been described in detail to clearly explain the present invention, and are not necessarily limited to those having all of the configurations described. In addition, it is possible to replace 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. It is also possible to add, delete, or replace other configurations with respect to the configuration of each embodiment.

10...tandem type oil pump, 11...pump body, 12...bolt, 13...high pressure pump cover, 14...bolt, 15...low pressure pump cover, 16...drive shaft, 16C...cylindrical portion, 16P...two-face width portion, 16S...spline portion, 17...low pressure side suction hole, 18...high pressure side discharge hole, 19...high pressure side suction hole, 20...low pressure side discharge hole, 21...vane pump rotor storage portion, 22...gear pump rotor storage portion, 23...partition wall, 24...bearing through hole, 25...po Pump body, 26...vane pump rotor, 27...adjustment ring, 28...pivot, 29...arm portion, 30...control spring, 31...vane, 32...vane ring, 33...suction portion, 34...discharge portion, 35...compression spring, 36...ball valve, 37...outer rotor, 38...inner rotor, 39...external teeth, 40...internal teeth, 41...small diameter portion, 42...inner rotor side bearing through hole, 43...two-sided width flat surface, 44...fitting hole, 45...spline teeth.

Claims (16)

a pump body including a high-pressure pump rotor accommodating portion, a low-pressure pump rotor accommodating portion, a partition wall that separates the high-pressure pump rotor accommodating portion from the low-pressure pump rotor accommodating portion, and a bearing through hole formed in the partition wall that connects the high-pressure pump rotor accommodating portion and the low-pressure pump rotor accommodating portion;
a drive shaft rotatably disposed in the bearing through hole and rotated by an external power source;
a high-pressure oil pump that is disposed in the high-pressure pump rotor accommodating portion, has a high-pressure pump rotor that is fixed to the drive shaft and restricted in its relative movement in the drive axis direction and in the rotational direction, and that pressurizes oil introduced from a first suction portion to a first discharge pressure and discharges it from a first discharge portion by driving the high-pressure pump rotor to rotate by the drive shaft, and lubricates the high-pressure pump rotor with the oil at the first discharge pressure;
a low-pressure oil pump that is disposed in the low-pressure pump rotor accommodating portion, has a low-pressure pump rotor that is freely movable relative to the drive shaft in a drive axial direction but is restricted in its movement in a rotational direction relative to the drive shaft, and that pressurizes the oil guided from a second suction portion at a second discharge pressure lower than the first discharge pressure discharged from a first discharge portion of the high-pressure oil pump and discharges it from the second discharge portion by driving the low-pressure pump rotor to rotate by the drive shaft, and lubricates the low-pressure pump rotor with the oil at the second discharge pressure ,
a low-pressure pump rotor-side bearing through hole is provided in the pump body between the low-pressure pump rotor accommodating portion and the bearing through hole, the low-pressure pump rotor-side bearing through hole being larger in diameter than the bearing through hole and being continuous with the low-pressure pump rotor accommodating portion which is smaller in diameter than the low-pressure pump rotor accommodating portion;
The low-pressure pump rotor is formed with a small-diameter shaft portion that is integral with the low-pressure pump rotor, and the small-diameter shaft portion is received in the low-pressure pump rotor-side bearing through hole and supported.
A tandem oil pump comprising: 2. The tandem oil pump according to claim 1,
The drive shaft has a fixed portion,
The high-pressure pump rotor is press-fitted and fixed to a fixing portion of the drive shaft,
The drive shaft has a pair of two-face width portions,
The low-pressure pump rotor has a pair of two-face width fitting portions that mesh with the pair of two-face width portions, and is movably fitted to the pair of two-face width portions. 2. The tandem oil pump according to claim 1,
The drive shaft has a fixed portion,
The high-pressure pump rotor is press-fitted and fixed to a fixing portion of the drive shaft,
The drive shaft has a male spline portion provided in an extending direction of the drive shaft,
A tandem oil pump, characterized in that the low-pressure pump rotor has a female spline portion that meshes with the male spline portion and is movably fitted relative to the male spline portion. 3. The tandem oil pump according to claim 2,
A tandem oil pump, characterized in that the axial length of the two-face width portion formed on the drive shaft is longer than the axial length of the low-pressure pump rotor. 4. The tandem oil pump according to claim 3,
A tandem oil pump, characterized in that the axial length of the male spline portion formed on the drive shaft is longer than the axial length of the low-pressure pump rotor. 2. The tandem oil pump according to claim 1,
a high-pressure pump cover that closes the high-pressure pump rotor accommodating portion and a low-pressure pump cover that is provided on the opposite side of the high-pressure pump cover and closes the low-pressure pump rotor accommodating portion are attached to the pump body;
the high-pressure pump rotor is disposed between the high-pressure pump cover and the partition wall and is fixed to the drive shaft;
The low-pressure pump rotor is disposed between the low-pressure pump cover and the partition wall, and is fitted to the drive shaft so as to be movable relative to the drive shaft.
A tandem oil pump comprising: 7. The tandem oil pump according to claim 6,
the high-pressure pump cover and the low-pressure pump cover are attached to the pump body along a plane perpendicular to an axis of the drive shaft,
the high-pressure pump cover is provided with a first discharge hole communicating with the first discharge portion that opens at a radial position relative to the drive shaft,
A second suction hole communicating with the second suction portion that opens at a position radially relative to the drive shaft is provided on the side of the pump body on which the low-pressure pump cover is provided.
A tandem oil pump comprising: 8. The tandem oil pump according to claim 7,
a pair of mounting portions provided on the pump body at radial positions relative to the drive shaft so as to sandwich the pump body and be attached to an internal combustion engine;
At least one of the mounting portions is provided with a second suction hole that is connected to the second suction portion of the low-pressure oil pump.
A tandem oil pump comprising: 2. The tandem oil pump according to claim 1,
The high pressure oil pump
the vane-type oil pump includes: an adjusting ring that is arranged to be able to swing in the high-pressure pump rotor housing portion and has a rotor housing portion provided therein; a pump rotor that is housed inside the adjusting ring; and a plurality of vanes that are housed on the outer peripheral surface of the pump rotor and form a plurality of hydraulic oil chambers to which oil is guided between the adjusting ring and the pump rotor, the vane-type oil pump sucking in oil from the first suction portion that opens into the hydraulic oil chamber that increases in volume as the drive shaft rotates and discharging oil from the first discharge portion that opens into the hydraulic oil chamber that decreases in volume as the drive shaft rotates.
A tandem oil pump comprising: 10. The tandem oil pump according to claim 9,
The low pressure oil pump
The low-pressure pump rotor accommodated in the low-pressure pump rotor accommodation portion is an outer rotor including a plurality of internal teeth on an inner circumferential side, and a gear-type oil pump having a plurality of external teeth that mesh with the plurality of internal teeth on an outer circumferential side, the outer rotor being accommodated inside the outer rotor and movably provided in the direction of the drive axis of the drive shaft.
A tandem oil pump comprising: 2. The tandem oil pump according to claim 1,
The high-pressure oil pump is a variable displacement oil feed pump that supplies pressurized oil to at least a main oil gallery of an internal combustion engine,
The low pressure oil pump is a scavenging oil pump that recovers oil from an oil pan of an internal combustion engine.
A tandem oil pump comprising: a pump body including a high-pressure pump rotor accommodating portion, a low-pressure pump rotor accommodating portion, a partition wall that separates the high-pressure pump rotor accommodating portion from the low-pressure pump rotor accommodating portion, and a bearing through hole formed in the partition wall that connects the high-pressure pump rotor accommodating portion and the low-pressure pump rotor accommodating portion;
a drive shaft rotatably disposed in the bearing through hole and rotated by an external power source;
a high-pressure oil pump that is disposed in the high-pressure pump rotor accommodating portion, has a high-pressure pump rotor press-fitted and fixed to the drive shaft, and performs a pumping action of oil at a first discharge pressure as the high-pressure pump rotor is rotationally driven by the drive shaft, and lubricates the high-pressure pump rotor with the oil at the first discharge pressure;
a low-pressure oil pump that is disposed in the low-pressure pump rotor accommodating portion, has a low-pressure pump rotor attached so as to be freely movable in a drive axial direction relative to the drive shaft, and performs a pumping action of the oil at a second discharge pressure lower than the first discharge pressure as the low-pressure pump rotor is rotationally driven by the drive shaft, and lubricates the low-pressure pump rotor with the oil at the second discharge pressure,
a low-pressure pump rotor-side bearing through hole is provided in the pump body between the low-pressure pump rotor accommodating portion and the bearing through hole, the low-pressure pump rotor-side bearing through hole being larger in diameter than the bearing through hole and being continuous with the low-pressure pump rotor accommodating portion which is smaller in diameter than the low-pressure pump rotor accommodating portion;
The low-pressure pump rotor is formed with a low-pressure pump rotor small diameter shaft portion that is integrally formed with the low-pressure pump rotor, and the low-pressure pump rotor small diameter shaft portion is received in the low-pressure pump rotor side bearing through hole and supported.
A tandem oil pump comprising: 13. The tandem oil pump according to claim 12,
The high-pressure oil pump is a variable displacement oil feed pump that supplies pressurized oil to at least a main oil gallery of an internal combustion engine,
The low pressure oil pump is a scavenging oil pump that recovers oil from an oil pan of the internal combustion engine.
A tandem oil pump comprising: 14. The tandem oil pump according to claim 13,
The variable displacement oil feed pump is a vane type oil pump,
The scavenging oil pump is a gear type oil pump.
A tandem oil pump comprising: 13. The tandem oil pump according to claim 12,
The drive shaft has a cylindrical portion and a spline portion or a two-face width portion,
The high-pressure pump rotor is press-fitted and fixed to the cylindrical portion,
The low-pressure pump rotor, which has a fitting hole having a shape similar to that of the spline portion or the two-face width portion, is fitted to the spline portion or the two-face width portion so as to be movable in the axial direction relative to the drive shaft.
A tandem oil pump comprising: 16. The tandem oil pump according to claim 15,
The axial length of the spline portion or the two-face width portion is formed to be longer than the axial length of the low-pressure pump rotor.
A tandem oil pump comprising:

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