Pump structure of an internal combustion engine

Abstract

To restrain inclination of an oil level OL2 by using the pump action of a scavenging pump 5 when the oil level inclines.SOLUTION: A scavenging pump 5 and a main oil pump are arranged in a lower part of a crankcase 6. The main oil pump sucks up lubricating oil from a suction port 9a of an oil strainer 9, and pumps it to each part. The scavenging pump 5 recovers the lubricating oil from a bearing part of a turbocharger, and returns it into the crankcase 6. An air introduction passage for negative pressure adjustment is connected to an oil suction passage of the scavenging pump 5, and an air introduction port 16a at a tip is opened in the crankcase 6. When an oil level OL2 inclines and reaches the air introduction port 16a, the lubricating oil near the oil level OL2 is returned into the crankcase 6 by the scavenging pump 5, and therefore further inclination of the oil level OL2 is restrained.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a pump structure for an internal combustion engine equipped with a scavenge pump that forcibly recovers used lubricating oil from a lubricated part. [Background technology]

[0002] Patent Document 1 discloses a configuration in which used lubricating oil supplied to the bearings of a turbocharger is forcibly recovered by a scavenge pump to prevent the oil from overflowing into the turbine or compressor. In particular, Patent Document 1 features a configuration in which an air inlet pipe with an orifice is connected to a recovery pipe extending from the bearings to the scavenge pump to create an appropriate negative pressure on the suction side of the scavenge pump. The tip opening of the air inlet pipe is positioned high enough to always protrude above the oil surface regardless of the vehicle's running state. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-280878 Summary of the Invention [Problem to be solved by the invention]

[0004] An internal combustion engine is typically equipped with an oil pump for supplying lubricating oil to various parts of the engine, and this oil pump draws up the lubricating oil stored in the bottom of the crankcase and pumps it to each part through a so-called oil gallery, etc. In such a configuration, when the vehicle tilts significantly, the oil pump's intake port (usually the intake port at the tip of the oil strainer) becomes exposed above the oil surface, causing a temporary inability to draw up lubricating oil.

[0005] The scavenge pump of Patent Document 1 mentioned above does nothing to contribute to the supply of lubricating oil in such a situation. [Means for solving the problem]

[0006] This invention uses lubricating oil stored in the bottom of the crankcase. From the oil strainer intake A main oil pump that sucks in oil and pumps it to each part of the internal combustion engine; A different part from the bottom of the crankcase A pump structure for an internal combustion engine, comprising: a scavenge pump that recovers used lubricating oil from a specific lubricated part and returns it to the inside of a crankcase; and a pump structure for an internal combustion engine, the pump structure being provided at a lower part of the internal combustion engine, an air introduction passage for adjusting negative pressure is connected to the oil suction passage that runs from the lubricated part to the suction side of the scavenge pump; The air inlet at the tip of this air inlet passage opens into the crankcase. And, The air inlet is When the oil level at the bottom of the crankcase is tilted, the lubricating oil flows in. The scavenge pump discharges oil from the discharge port of the scavenge pump, which is positioned above the inclined oil surface. The height position is set so that it can be returned to the inside of the crankcase.

[0007] For example, when the vehicle is stopped on a flat road, the air inlet is located above the oil surface, allowing air to be introduced from inside the crankcase, thereby maintaining an appropriate negative pressure in the oil intake passage.

[0008] On the other hand, if the oil level at the bottom of the crankcase tilts to a certain degree due to tilting of the vehicle or the like and reaches the air inlet, lubricating oil flows in from the air inlet and the scavenge pump acts to return it to the inside of the crankcase, thereby at least partially suppressing further changes in the oil level. Note that the "tilt of the oil level" refers to the tilt relative to the crankcase or the like. [Effects of the Invention]

[0009] According to this invention, the scavenge pump functions to suppress changes in the oil level at the bottom of the crankcase when the oil level tilts due to tilting of the vehicle, etc. This allows the main oil pump to more reliably suck up lubricating oil. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is an explanatory diagram showing a schematic configuration of a first embodiment in which the present invention is applied to a V-type internal combustion engine; [Figure 2] FIG. 2 is a front view showing the configuration of the main part including the scavenge pump. [Figure 3] FIG. 4 is a perspective view showing a main part of a mounting flange portion of the housing. [Figure 4] FIG. 4 is an explanatory diagram showing the relationship between the oil level and when the internal combustion engine is tilted. [Figure 5] FIG. 10 is an explanatory diagram that schematically shows the configuration of a second embodiment in which the present invention is applied to an in-line multi-cylinder internal combustion engine. DETAILED DESCRIPTION OF THE INVENTION

[0011] An embodiment of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a diagram illustrating the configuration of a first embodiment in which the present invention is applied to a V6 internal combustion engine 1. FIG. 2 shows the configuration of a pump portion, which is a key component of the engine. The internal combustion engine 1 of this embodiment is mounted in a vehicle in a so-called longitudinal orientation, and superchargers, more specifically turbochargers 2 (2L, 2R), are disposed on the outside of each of the left and right banks. Lubricating oil is supplied to the bearings of the turbocharger 2 from appropriate locations on the internal combustion engine 1, such as the cylinder heads 3 (3L, 3R) of the left and right banks, as indicated by dashed lines O1.

[0012] A scavenge pump 5 and a main oil pump (not shown) are disposed below the internal combustion engine 1, and these pumps are housed in a crankcase 6. In one embodiment, the scavenge pump 5 and the main oil pump are integrated into one unit so that they form a single housing 7 (see FIG. 2). More specifically, the pump mechanism of the scavenge pump 5 and the pump mechanism of the main oil pump are disposed in tandem (in other words, in series) within the housing 7 so that both are rotationally driven by a common rotating shaft, and power from the crankshaft 8 is transmitted to the rotating shaft via a chain mechanism (not shown), so that both the scavenge pump 5 and the main oil pump are always driven while the internal combustion engine 1 is rotating.

[0013] Lubricating oil is stored at the bottom of the crankcase 6. The main oil pump draws up the lubricating oil stored at the bottom of the crankcase 6 and pumps it to various parts of the internal combustion engine 1 via an oil gallery or the like. As is well known, this lubricating oil lubricates various parts, such as the piston-crank mechanism including the crankshaft 8 and the valve mechanism in the cylinder head 3, and some of the lubricating oil is also used for cooling purposes. The lubricating oil used in the cylinder head 3 and the like basically flows down into the crankcase 6 due to its own weight and is collected at the bottom of the crankcase 6. Figure 2 shows an oil strainer 9 provided on the suction side of the main oil pump. This oil strainer 9 is cylindrical and made of synthetic resin or the like. It is connected to the suction section of the main oil pump in the housing 7, and its opening at the bottom, which extends toward the bottom of the crankcase 6, essentially serves as the suction port 9a of the main oil pump. Therefore, the main oil pump draws lubricating oil through this suction port 9a.

[0014] As shown in FIG. 1 , the main body of the internal combustion engine 1 of this embodiment is composed of a cylinder block 11 with six cylinders arranged in a V-shape and a ladder frame 12 attached to the underside of the cylinder block 11. An oil pan 13 is attached to the underside of the ladder frame 12. Like the cylinder block 11, the ladder frame 12 is made of die-cast aluminum alloy or the like. It is integrally cast with a pair of side walls extending in the longitudinal direction of the engine and connected to the skirt of the cylinder block 11, and a plurality of bearing caps extending in the transverse direction of the engine to connect the pair of side walls between the cylinders and at both the front and rear ends. In this embodiment, the ladder frame 12 and the cylinder block 11 correspond to main body components that make up the main body of the internal combustion engine 1. The crankshaft 8 is rotatably supported between the bulkhead of the cylinder block 11 and the bearing caps of the ladder frame 12. The crankcase 6 , which is the space in which the crankshaft 8 and the connecting rods move, is composed of three components: a skirt portion of a cylinder block 11 , a ladder frame 12 , and an oil pan 13 .

[0015] As shown by dashed line O2 in FIG. 1 , the scavenge pump 5 forcibly recovers used lubricating oil from the bearings of the turbochargers 2, which are lubricated parts, and returns the recovered lubricating oil to the crankcase 6. In one embodiment, the scavenge pump 5 is a trochoid pump. Other types of pumps may also be used. The scavenge pump 5 has a pair of oil suction passages 15 connected to its suction side, and these oil suction passages 15 communicate with the bearings of the turbochargers 2 (2L, 2R) on the left and right banks, respectively. Furthermore, as shown schematically in FIG. 1 , an air inlet passage 16 for adjusting negative pressure is connected to each oil suction passage 15. The passage area of ​​each air inlet passage 16 is set to act as a kind of orifice to obtain an appropriate air flow rate or pressure difference. Air inlet ports 16a at the tip of each of the oil inlet passages 15 open into the crankcase 6.

[0016] The two air inlets 16a are arranged at positions near both sides of the crankcase 6, away from the rotation center of the crankshaft 8 in the width direction of the internal combustion engine 1. A pair of oil suction passages 15 extend to the left and right corresponding to the left and right banks, and the corresponding air inlets 16a are arranged on the same left and right side.

[0017] Next, the configuration of the scavenge pump 5 and the air introduction passage 16 of one embodiment will be described with reference to Figures 2 and 3. Figure 2 is a front view of the housing 7 that accommodates the scavenge pump 5 and the main oil pump, as seen along the axial direction of the crankshaft 8. More specifically, it shows a view from the rear to the front of the internal combustion engine 1 inside the crankcase 6. As described above, the pump mechanism of the scavenge pump 5, which is arranged in tandem, is located relatively to the front of the figure (rear in the longitudinal direction of the internal combustion engine 1), while the pump mechanism of the main oil pump is located behind the scavenge pump 5 in the figure (forward in the longitudinal direction of the internal combustion engine 1). The discharge port 21 of the scavenge pump 5 is located approximately in the center of the end of the scavenge pump 5, and the lubricating oil discharged from here returns to the bottom of the crankcase 6. In addition, the oil strainer 9 for the main oil pump described above extends from a position adjacent to the end of the scavenge pump 5, and the intake port 9a at its lower end opens downward.

[0018] The housing 7 has left and right wing portions 7b, 7c extending diagonally upward from a central portion 7a containing the pump mechanism. Mounting flange portions 7d, 7e are provided at the tips of the wing portions 7b, 7c, extending longitudinally in the axial direction of the crankshaft 8. The mounting flange portions 7d, 7e are attached to the underside of the ladder frame 12 (more specifically, the front end portion of the internal combustion engine 1 in the longitudinal direction). A plurality of bolts (not shown) penetrate the mounting flange portions 7d, 7e and screw into the ladder frame 12, thereby securing the housing 7 to the ladder frame 12. Note that FIG. 2 shows a simplified illustration of the ladder frame 12. The mounting surfaces on the ladder frame 12 side and the mounting flange portions 7d, 7e side (see FIG. 3), which are in contact with each other, are both machined flat and are in close contact with each other to ensure sufficient oil-tightness and airtightness.

[0019] The left and right oil suction passages 15 that communicate with the suction side of the scavenge pump 5 are formed through the inside of the wing portions 7b, 7c, respectively, and cross the mounting surfaces of the mounting flange portions 7d, 7e and the ladder frame 12 to communicate with the oil suction passage inside the ladder frame 12. The oil suction passage that passes through the inside of the ladder frame 12 further passes through the inside of the cylinder block 11 and ultimately communicates with the bearing portion of the turbocharger 2, which is the part to be lubricated, as described in FIG.

[0020] FIG. 3 shows the main configuration of one mounting flange 7d (the other mounting flange 7e is similar). As shown, a bulge 7f is provided near the rear end of the diagonally extending wing 7b to form a conduit, and an oil suction passage 15 is formed through the interior of this bulge 7f. The housing 7 is constructed as a casting using, for example, an aluminum alloy, and the oil suction passage 15 is formed by casting or drilling. Where the tip of this oil suction passage 15 opens to the mounting surface 22 of the mounting flange 7d, a recess 23 is formed as an oil reservoir. The opening is larger than the cross-section of the oil suction passage 15. Therefore, the oil suction passage (not shown) extending vertically inside the ladder frame 12 and the oil suction passage 15 on the housing 7 side are connected to each other through the space within this recess 23.

[0021] As shown in FIG. 3 , the air introduction passage 16 is formed in the rear end of the mounting flange 7d (the end closest to the recess 23) as a groove with a rectangular cross section. For example, the air introduction passage 16 is formed by linearly machining a groove in the mounting surface 22. The mounting surface 22 on the housing 7 side is brought into close contact with the mounting surface on the ladder frame 12 side, thereby forming the air introduction passage 16 in the shape of a passage with a rectangular cross section. One end of the air introduction passage 16 opens toward the crankcase 6 as an air introduction port 16a, and the other end opens into the recess 23. In particular, the groove that becomes the air introduction passage 16 is formed along the axial direction of the crankshaft 8 (the front-rear direction of the internal combustion engine 1). Therefore, the air introduction port 16a opens toward the axial direction of the crankshaft 8. Forming the air introduction passage 16 as a groove in the mounting surface 22 in this way facilitates its formation and also makes it easy to ensure an appropriate passage cross-sectional area as a type of orifice.

[0022] 2 shows the oil level OL1 when the vehicle equipped with the internal combustion engine 1 is horizontal (for example, when traveling on a flat road). This corresponds to the oil level position during operation. When the vehicle and, in turn, the internal combustion engine 1 are in a horizontal position, the pair of air inlets 16a are both above the oil level OL1 and open to the crankcase 6. Therefore, air is appropriately introduced into the oil intake passage 15, and the pressure on the intake side of the scavenge pump 5 is adjusted to an appropriate negative pressure.

[0023] Furthermore, since the air inlet 16a is open toward the axial direction of the crankshaft 8, oil mist that is scattered as the crankshaft 8 rotates does not directly enter the air inlet 16a, and only air can be introduced.

[0024] On the other hand, the intake port 9a of the oil strainer 9 of the main oil pump is submerged below the oil level OL1. Therefore, as the main oil pump is driven, lubricating oil is sucked up and pumped to each part of the internal combustion engine 1.

[0025] 4 is an explanatory diagram showing the positional relationship between the oil level OL2 and the air inlet 16a when a vehicle equipped with a longitudinally mounted internal combustion engine 1 tilts to the left or right while traveling. In this figure, the oil level OL2 has just reached one of the air inlets 16a. At this stage, the intake port 9a of the oil strainer 9 is located slightly below the oil level OL2. If the oil level OL2 tilts further than this, the intake port 9a will be exposed, making it difficult to suck up the lubricating oil.

[0026] When the internal combustion engine 1 is tilted relatively greatly in this manner and the oil level OL2 reaches the height of the air inlet 16a, the lubricating oil near the air inlet 16a begins to flow into the air inlet 16a. The lubricating oil that enters through the air inlet 16a is sucked into the scavenge pump 5 through the air inlet passage 16 and the oil suction passage 15, and is returned to the crankcase 6 through the discharge port 21 by the pumping action of the scavenge pump 5 (see dashed line O3). Note that the discharge port 21 is preferably positioned above the oil level OL2 when the engine is tilted. Furthermore, the air inlet 16a into which the lubricating oil flows is preferably positioned relatively higher than the suction port of the pump mechanism of the scavenge pump 5 in the state shown in FIG. 4.

[0027] 4, the scavenge pump 5 collects lubricating oil from the crankcase 6 through one air inlet 16a and returns it to the crankcase 6. This makes it difficult for the oil level OL2 to rise above the air inlet 16a, thereby suppressing any further rise in the oil level OL2, i.e., the relative tilt of the oil level OL2. This makes it difficult for the intake port 9a of the oil strainer 9 to become exposed when the vehicle tilts, ensuring that the main oil pump continues to lubricate each part more reliably.

[0028] It is desirable that the positional relationship between the oil strainer 9 and the oil level OL2 be such that the intake port 9a of the oil strainer 9 is not yet exposed above the oil level OL2 (the entire intake port 9a is below the oil level OL2) when the oil level OL2 reaches the air inlet 16a as the internal combustion engine 1 tilts. In other words, the positional relationship between the oil strainer 9 and the oil level OL2 is preferably set so that when the internal combustion engine 1 tilts around the crankshaft 8, the relatively inclined oil level OL2 reaches the air inlet 16a before the intake port 9a of the oil strainer 9 of the main oil pump becomes exposed above the oil level OL2.

[0029] The same applies when the oil level tilts in the opposite direction to that shown in FIG. 4, and when the oil level reaches the other air inlet 16 a, the lubricating oil is recovered by the scavenge pump 5 and discharged into the crankcase 6.

[0030] Therefore, the same effect can be obtained whether the internal combustion engine 1 is tilted to the left or right. In addition to when the vehicle (internal combustion engine 1) is tilted, the same effect can also be obtained when the oil level is tilted due to centrifugal force when the vehicle turns.

[0031] While one embodiment in which the present invention is applied to a V-type internal combustion engine 1 has been described above, the present invention can also be applied to an in-line multi-cylinder internal combustion engine 101, as shown in FIG. 5 . As in the first embodiment, the scavenge pump 5 recovers used lubricating oil from the bearings of the turbocharger 2, which is the part to be lubricated. An air introduction passage 16 is connected to the middle of the oil suction passage 15 of the scavenge pump 5. An air introduction port 16a at the end of the air introduction passage 16 is above the oil level when the vehicle is level. However, when the vehicle tilts and the oil level reaches the air introduction port 16a, the air introduction passage 16 recovers lubricating oil from within the crankcase 6 and returns it to the crankcase 6, suppressing further fluctuations in the oil level.

[0032] In the first and second embodiments described above, the bearing portion of the turbocharger 2 is cited as the lubricated portion from which the scavenge pump 5 recovers lubricating oil, but the present invention can be similarly applied to configurations in which the scavenge pump recovers lubricating oil from other lubricated portions.

[0033] Also, the main oil pump may be located in any position. [Explanation of symbols]

[0034] 1,101...Internal combustion engine 2...Turbocharger 3...Cylinder head 5…Scavenge Pump 6...Crankcase 7. Housing 9...Oil strainer 9a…Inlet 11...Cylinder block 12...Ladder frame 15...Oil intake passage 16...Air intake passage 16a...Air inlet

Claims

1. A pump structure for an internal combustion engine, comprising: a main oil pump that sucks lubricating oil stored in the bottom of the crankcase through an intake port of an oil strainer and pumps it to each part of the internal combustion engine; and a scavenge pump that collects used lubricating oil from specific lubricated parts other than the bottom of the crankcase and returns it to the inside of the crankcase, the pump being provided at the bottom of the internal combustion engine; an air introduction passage for adjusting negative pressure is connected to the oil suction passage that runs from the lubricated part to the suction side of the scavenge pump; The air inlet at the tip of the air inlet passage is open to the crankcase, The air inlet is positioned at a height such that when the oil level at the bottom of the crankcase tilts, lubricating oil flows in and is returned to the inside of the crankcase through the discharge port of the scavenge pump, which is positioned above the tilted oil level, by the action of the scavenge pump. Pump structure of an internal combustion engine.

2. the air inlet is disposed at a position near one or both sides of the crankcase away from the rotation center of the crankshaft in the width direction of the internal combustion engine.

2. A pump structure for an internal combustion engine according to claim 1.

3. a positional relationship between the main oil pump and the air inlet is set so that, when the internal combustion engine is tilted around the crankshaft, the oil level reaches the air inlet before the intake port of the oil strainer of the main oil pump is exposed from the oil level.

3. A pump structure for an internal combustion engine according to claim 2.

4. the oil suction passage extends from the scavenge pump in the width direction of the internal combustion engine, an air introduction passage having an air introduction port at a position separated in the width direction of the same internal combustion engine is connected to the oil suction passage; 4. A pump structure for an internal combustion engine according to claim 2 or 3.

5. a housing of the scavenge pump attached to a lower surface of a main body component that constitutes a main body portion of the internal combustion engine, An oil suction passage is provided between the main body component and the housing, crossing the mounting surfaces of both components, The air introduction passage is formed in a groove shape on the mounting surface of the housing, one end of which joins with the oil suction passage and the other end of which opens as an air introduction port. The pump structure for an internal combustion engine according to any one of claims 1 to 4.

6. The air inlet is open toward the axial direction of the crankshaft.

6. A pump structure for an internal combustion engine according to claim 5.

7. the internal combustion engine is a V-type internal combustion engine arranged longitudinally in a vehicle and is provided with a pair of air inlets; When the vehicle tilts left or right, lubricating oil is drawn in from one of the air intake ports. The pump structure for an internal combustion engine according to any one of claims 1 to 6.

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