Engine unit

Abstract

An engine unit (EU) according to the present disclosure comprises a scavenge pump (30) that suctions and discharges a lubricating liquid (OL) from inside a lubricating liquid pan (14) of an engine (E), a lubricating liquid tank (28) that stores the lubricating liquid (OL) discharged by the scavenge pump (30), and a feed pump (32) that supplies the lubricating liquid (OL) led out from the lubricating liquid tank (28) to a to-be-lubricated portion of the engine (E). The scavenge pump (30) and the feed pump (32) are disposed inside the lubricating liquid pan (14). The scavenge pump (30) and the feed pump (32) are trochoid pumps, and a rotary shaft of the scavenge pump (30) and a rotary shaft of the feed pump (32) are coaxial. The scavenge pump (30) and the feed pump (32) are such that the offsets of respective pump rotation axes relative to the outside diameter are set in mutually opposite directions.

Description

engine unit Related Applications

[0001] This application claims priority to Japanese Patent Application No. 2024-017005, filed February 7, 2024, the entire contents of which are incorporated herein by reference.

[0002] The present disclosure relates to a dry sump lubrication engine unit.

[0003] Dry sump lubrication engines are sometimes used as drive sources for vehicles (see, for example, Patent Document 1). In dry sump lubrication engines, lubricating fluid is stored in a lubricating fluid tank, allowing for a stable supply of lubricating fluid without being affected by changes in the vehicle's attitude. This reduces the stirring resistance of the crankshaft, improving output. Furthermore, because the lubricating fluid pan can be made smaller, the engine can be made smaller in the vertical direction, lowering the center of gravity.

[0004] JP 2009-013887 A

[0005] In a dry sump lubrication engine, a scavenge pump and a feed pump are located at the bottom of the engine, and the scavenge pump discharges lubricating fluid into a lubricating fluid tank, while the feed pump receives lubricating fluid from the lubricating fluid tank. Therefore, it is preferable that the scavenge pump outlet and the feed pump inlet are located on the same side of the engine.

[0006] The disclosure of the present application provides an engine unit that allows for simplified piping to and from the lubricating fluid tank.

[0007] The engine unit of the present disclosure includes a scavenge pump that sucks and discharges lubricating liquid from a lubricating liquid pan of an engine, a lubricating liquid tank that stores the lubricating liquid discharged by the scavenge pump, and a feed pump that supplies the lubricating liquid drawn from the lubricating liquid tank to lubricated parts of the engine. The scavenge pump and the feed pump are disposed inside the lubricating liquid pan, and the scavenge pump and the feed pump are trochoid pumps, with the rotational axes of the scavenge pump and the feed pump being coaxial. The offsets of the pump rotational axes relative to the outer diameters of the scavenge pump and the feed pump are set in opposite directions.

[0008] Here, "the offset of the pump rotation axis relative to the outer diameter is set in opposite directions" means that, when viewed from the direction of the pump rotation axis, a line segment connecting the center of the outer diameter of the scavenge pump, the common pump rotation axis, and the center of the outer diameter of the feed pump forms an obtuse angle. This also includes a configuration in which the center of the outer diameter of the scavenge pump, the common pump rotation axis, and the center of the outer diameter of the feed pump are aligned in a straight line. In other words, "the offset of the pump rotation axis relative to the outer diameter is set in opposite directions" means that the center of the outer diameter of the scavenge pump and the center of the outer diameter of the feed pump are located in regions on opposite sides of the common pump rotation axis.

[0009] According to the engine unit of the present disclosure, the scavenge pump and the feed pump have their rotational axes offset in opposite directions relative to their outer diameters. In other words, the center of the outer diameter of the scavenge pump and the center of the outer diameter of the feed pump are located on opposite sides of the common pump rotational axis. The flow direction of a trochoid pump is determined by the offset direction, and reversing the offset allows the suction and discharge ports to be reversed. This allows the two pumps to be driven coaxially while the scavenge pump discharge port and the feed pump suction port to be located on the same side of the engine. This simplifies the piping leading to and from the lubricating liquid tank.

[0010] Any combination of at least two features disclosed in the claims and / or the specification and / or the drawings is included in the present disclosure. In particular, any combination of two or more of the claims is included in the present disclosure.

[0011] The present disclosure will be more clearly understood from the following description of preferred embodiments with reference to the accompanying drawings. However, the embodiments and drawings are merely for illustration and explanation purposes and should not be used to define the scope of the present disclosure. The scope of the present disclosure is defined by the accompanying claims. In the accompanying drawings, the same part numbers in multiple drawings indicate the same parts.

[0023] Figure 1 is a side view of an engine unit according to a first embodiment of the present disclosure. Figure 2 is a front view of the engine unit. Figure 3 is a perspective view of a scavenge pump and a feed pump of the engine unit. Figure 4 is a bottom view of the engine unit as seen from below. Figure 5 is a view showing the arrangement of rotors of the scavenge pump and the feed pump.

[0012] A preferred embodiment of the present disclosure will now be described with reference to Figures 1 to 5. The engine E of this embodiment is a reciprocating engine, and is used, for example, in an airplane in which a propeller is located at the tip of the fuselage. In this case, the engine E is housed within the fuselage, and engine power is transmitted to the propeller. The use of the engine E is not limited to this, and it can also be used, for example, as a drive source for a ship, or as a drive source for vehicles such as motorcycles and automobiles.

[0013] In the following description, the "width direction WD" refers to the direction in which the crankshaft 2 of the engine E extends, i.e., the axial direction of the crankshaft 2. In the width direction WD, the direction toward the width center is referred to as the "width inner side," and the direction away from the width center is referred to as the "width outer side." The "reciprocating direction VD" refers to the direction of reciprocating motion of the piston of the engine E. The direction perpendicular to both the "width direction WD" and the "reciprocating direction VD" is referred to as the "perpendicular direction PD."

[0014] The engine E of this embodiment is a six-cylinder engine with six cylinders aligned in the direction of the crankshaft 2. However, the number of cylinders is not limited to this and may be, for example, four. Furthermore, although the engine E of this embodiment is a gasoline engine, the fuel is not limited to gasoline. The crankshaft 2 converts the reciprocating motion of the pistons 3 into rotational motion.

[0015] The engine E has a crankcase 4 that supports the crankshaft 2, a cylinder 6 that protrudes from the crankcase 4 in one direction in the reciprocating direction VD, a cylinder head 8 connected to the protruding end of the cylinder 6, and a head cover 12 connected to the upper end of the cylinder head 8. In the following description, the direction in the reciprocating direction VD in which the cylinder 6 protrudes from the crankcase 4 is referred to as "upward," and the opposite side is referred to as "downward."

[0016] The crankcase 4 is divided into two parts, a lower crankcase 4a and an upper crankcase 4b. In this embodiment, the upper crankcase 4b and the cylinder 6 are integrally formed by molding. However, the upper crankcase 4b and the cylinder 6 may be separate bodies. In the following description, the integrated upper crankcase 4b and the cylinder 6 are referred to as a cylinder block 10.

[0017] The engine E further has an oil pan 14 connected to the lower end of the crankcase 4. The oil pan 14 stores engine oil OL, which is a type of lubricating liquid that lubricates parts of the engine E that need to be lubricated. In other words, the oil pan 14 serves as a lubricating liquid pan that stores the lubricating liquid.

[0018] An intake port 16 opens on one side (right side in FIG. 1) of the cylinder head 8 in the orthogonal direction PD, and an exhaust port 18 opens on the other side (left side in FIG. 1) in the orthogonal direction PD. In the following description, the intake port side in the orthogonal direction PD will be simply referred to as the "intake side," and the exhaust port side will be simply referred to as the "exhaust side."

[0019] The intake port 16 and the exhaust port 18 are passages formed inside the cylinder head 8. The upstream end of the intake port 16 opens to one side of the cylinder head 8 in the orthogonal direction PD, and the downstream end opens to a combustion chamber 20 inside the cylinder 6. The upstream end of the exhaust port 18 opens to the combustion chamber 20 inside the cylinder 6, and the downstream end opens to the front of the other side of the cylinder head 8 in the orthogonal direction PD. An intake port 16 is formed for each cylinder. Similarly, an exhaust port 18 is formed for each cylinder.

[0020] External air is supplied as intake air from the intake port 16 to the combustion chamber 20, and fuel is injected into the combustion chamber 20 from the injector 22 to form a fuel-air mixture. The mixture in the combustion chamber 20 is ignited by the spark plug 24 and burns. Exhaust gas after combustion is discharged to the outside of the engine from the exhaust port 18.

[0021] 2 is a front view of the engine E as seen from the intake side in the orthogonal direction PD. As shown in the figure, an output shaft 25 and a reduction mechanism 26 are provided on one side of the engine E in the width direction WD (the right side in FIG. 2). The rotational force of the crankshaft 2 is reduced in speed by the reduction mechanism 26 and transmitted to the output shaft 25. An aircraft propeller, a vehicle wheel, a turbine rotor blade, a compressor impeller, etc. are connected to the output shaft 25 directly or via a power transmission member.

[0022] The engine E of the present disclosure is a dry sump lubrication engine having a scavenge pump 30 that sucks oil OL from the oil pan 14 and discharges it into the oil tank 28. In other words, the oil tank 28 constitutes a lubricating liquid tank that stores lubricating liquid. The engine E of the present disclosure further includes a feed pump 32 that supplies the oil OL drawn from the oil tank 28 to parts of the engine E that need to be lubricated.

[0023] In this embodiment, the oil tank 28 is provided outside the engine E, i.e., separated from the engine E. The oil OL discharged from the scavenge pump 30 is stored in the oil tank 28 and then pressurized by the feed pump 32 to lubricate the lubricated parts of the engine E. After lubricating the lubricated parts, the oil is returned to the oil pan 14. However, the oil tank 28 may also be provided inside the engine E.

[0024] In this embodiment, the oil pan 14 has a bottom wall 14a that forms the deepest part, and an inclined wall 14b that extends horizontally from the bottom wall 14a, and in this embodiment, slopes upward as it moves away from the bottom wall 14a in the engine width direction WD.

[0025] In this embodiment, the scavenge pump 30 and the feed pump 32 are trochoid pumps and are attached to the crankcase 4. Specifically, the scavenge pump 30 and the feed pump 32 are attached to the lower end of the crankcase 4. However, the scavenge pump 30 and the feed pump 32 may also be attached to the oil pan 14.

[0026] In this embodiment, the scavenge pump 30 is disposed inside the oil pan 14. Specifically, the scavenge pump 30 is disposed in the deepest part of the oil pan 14. More specifically, the suction port 30a of the scavenge pump 30 is disposed in the deepest part of the oil pan 14. In other words, the suction port 30a of the scavenge pump 30 is disposed at a low position inside the oil pan 14.

[0027] In this embodiment, the scavenge pump 30 is driven in conjunction with the rotation of the crankshaft 2. More specifically, the rotational force of the crankshaft 2 is transmitted to the scavenge pump 30 by a power transmission member 34 such as a drive chain.

[0028] In this embodiment, the feed pump 32 is also disposed within the oil pan 14. Specifically, the feed pump 32 is disposed inside the oil pan 14 on one side in the width direction WD of the engine E (the right side in FIG. 2 ). The scavenge pump 30 and the feed pump 32 are disposed side by side in the engine width direction WD. In this embodiment, the suction port 30a of the scavenge pump 30 is disposed below the entire feed pump 32.

[0029] The feed pump 32 pressurizes the oil OL stored in the oil tank 28 and pumps it to the parts of the engine E that need to be lubricated. The oil OL pumped by the feed pump 32 is first supplied to the main oil gallery 36. Of the passages inside the engine through which the oil OL pressurized by the feed pump 32 flows, the main oil gallery 36 is the largest diameter passage into which the oil OL from the feed pump 32 first flows. Of the passages inside the engine, the main oil gallery 36 is also the passage with the highest pressure. As shown in FIG. 1 , in this embodiment, the main oil gallery 36 is provided on the exhaust side. The main oil gallery 36 is provided with an oil jet that sprays the oil OL onto the back of the piston 3.

[0030] In this embodiment, the feed pump 32 is also driven in conjunction with the rotation of the crankshaft 2. More specifically, the rotational force of the crankshaft 2 is transmitted to the feed pump 32 by a power transmission member 34 such as a drive chain.

[0031] 2, in this embodiment, the rotational force of the crankshaft 2 is transmitted to both the scavenge pump 30 and the feed pump 32 by a common power transmission member 34. Specifically, a rotating shaft 30s of the scavenge pump 30 and a rotating shaft 32s of the feed pump 32 are concentrically arranged, and the two rotating shafts 30s, 32s are connected to each other. The power transmission member 34 is stretched across the rotating shaft 32s of the feed pump 32, and the rotational force of the crankshaft 2 is transmitted via the power transmission member 34 to the rotating shaft 32s of the feed pump 32 and to the rotating shaft 30s of the scavenge pump 30 connected thereto.

[0032] When the engine E starts, the scavenge pump 30 and the feed pump 32 are driven in conjunction with the rotation of the crankshaft 2. The feed pump 32 pumps the oil OL stored in the oil tank 28 to the main oil gallery 36. The oil OL is supplied from the main oil gallery 36 to the parts of the engine E that need to be lubricated, and after lubricating the parts, is returned to the oil pan 14. The oil OL in the oil pan 14 is recovered by the scavenge pump 30 and supplied to the oil tank 28.

[0033] As shown in Fig. 3, the discharge port 30b of the scavenge pump 30 and the suction port 32a of the feed pump 32 are arranged on the same side in the orthogonal direction PD. In this embodiment, as shown in Fig. 4, the discharge port 30b of the scavenge pump 30 and the suction port 32a of the feed pump 32 are arranged on the intake side in the orthogonal direction PD.

[0034] 1, the discharge port 32b of the feed pump 32 is disposed on the side in the orthogonal direction PD where the piston jet is disposed, i.e., on the exhaust side where the main oil gallery 36 is disposed. As such, as shown in Fig. 4, the discharge port 30b of the scavenge pump 30 and the suction port 32a of the feed pump 32 are disposed on the intake side of the center line CL of the engine E in the orthogonal direction PD, and the discharge port 32b of the feed pump 32 is disposed on the exhaust side.

[0035] 5, the offsets of the pump rotation axes 30s, 32s relative to the outer diameters of the scavenge pump 30 and the feed pump 32 are set in opposite directions. Here, "the offsets of the pump rotation axes relative to the outer diameters are set in opposite directions" means that, when viewed from the direction of the axes AX of the pump rotation axes 30s, 32s, an obtuse angle is formed between the center 30c of the outer diameter (outer rotor 30o) of the scavenge pump 30, the axis AX of the pump rotation axes 30s, 32s (inner rotors 30i, 32i), and the center 32c of the outer diameter (outer rotor 32o) of the feed pump 32.

[0036] Furthermore, "the offset of the pump rotation axis with respect to the outer diameter is set in opposite directions" also includes a case where the line segment (30c-AX-32c) is aligned in a straight line, and in this embodiment, the line segment (30c-AX-32c) is aligned in a straight line. In other words, "the offset of the pump rotation axis with respect to the outer diameter is set in opposite directions" means that the center 30c of the outer rotor 30o of the scavenge pump 30 and the center 32c of the outer rotor 32o of the feed pump 32 are located in opposite regions across the axis AX of the common pump rotation axis 30s, 32s (inner rotors 30i, 32i).

[0037] In a trochoid pump, the fluid flow is determined by the offset direction, or the direction of displacement of the outer rotor relative to the inner rotor. In other words, reversing the offset direction reverses the fluid flow direction. In other words, reversing the offset direction allows the suction and discharge ports of the trochoid pump to be reversed.

[0038] In this embodiment, the center 30c of the outer rotor 30o of the scavenge pump 30 is located below the axis AX of the pump rotary shaft 30s, and the center 32c of the outer rotor 32o of the feed pump 32 is located above the axis AX of the pump rotary shaft 30s. In the scavenge pump 30 of this embodiment, the oil OL flows from the exhaust side into the rotors 30i, 30o through the suction port 30a and is discharged from the rotors 30i, 30o to the intake side. On the other hand, in the feed pump 32 of this embodiment, the oil OL flows from the intake side into the rotors 32i, 32o through the suction port 32a and is discharged from the rotors 32i, 32o to the exhaust side.

[0039] As shown in FIG. 1 , in this embodiment, a main oil gallery 36 is disposed on the exhaust side of the crankcase 4 in the orthogonal direction PD. Providing the main oil gallery 36 on the exhaust side simplifies the structure for the convenience of the piston jet that injects oil OL into the piston 3. Oil OL is supplied to this main gallery 36 from the feed pump 32. As described above, the trochoid pump takes in oil from one side of the rotor as viewed from the axial direction and discharges it to the other side. Therefore, when discharging oil OL to the exhaust side in the orthogonal direction PD, the oil OL is drawn in from the intake side of the feed pump 32. In other words, the intake port 32 a of the feed pump 32 is disposed on the intake side in the orthogonal direction PD.

[0040] The oil OL discharged from the scavenge pump 30 flows toward the oil tank 28, and is supplied from the oil tank 28 to the feed pump 32. Therefore, it is preferable that the discharge port 32b of the scavenge pump 30 and the suction port 32a of the feed pump 32 are on the same side. When the suction port 32a of the feed pump 32 is provided on the intake side in the orthogonal direction PD as described above, the discharge port 30b of the scavenge pump 30 is also provided on the intake side. Furthermore, providing the oil tank 28 on the intake side can reduce the effect of heat from the engine on the oil tank 28. Therefore, the discharge port 30b of the scavenge pump 30 and the suction port 32a of the feed pump 32 are provided on the intake side in the orthogonal direction PD.

[0041] Since both the scavenge pump 30 and the feed pump 32 are driven by the power of the crankshaft 2, it is efficient to rotate the two pumps 30, 32 on the same shaft. For this reason, it is not easy to arrange the discharge direction of the scavenge pump 30 and the suction direction of the feed pump 32 on the same side.

[0042] In this embodiment, the two pumps 30, 32 are rotated on the same shaft, and the displacement direction of the outer rotors 30o, 32o relative to the inner rotors 30i, 32i, i.e., the offset direction, is reversed to reverse the flow direction of oil OL in the scavenge pump 30 and the feed pump 32. In a trochoid pump, the flow is determined by the offset direction, and by reversing the offset direction in the scavenge pump 30 and the feed pump 32, the suction ports 30a, 32a and the discharge ports 30b, 32b can be reversed.

[0043] According to the above configuration, the pump rotation axes 30s, 32s of the scavenge pump 30 and the feed pump 32 are offset in opposite directions relative to the outer rotors 30o, 32o. In other words, the center 30c of the outer rotor 30o of the scavenge pump 30 and the center 32c of the outer rotor 32o of the feed pump 32 are located on opposite sides of the axis AX of the common pump rotation axes 30s, 32s. This allows the two pumps 30, 32 to be driven coaxially, while the discharge port 30b of the scavenge pump 30 and the suction port 32a of the feed pump 32 being located on the same side. As a result, the piping leading to and from the oil tank 28 is simplified.

[0044] In this embodiment, the suction port 30a of the scavenge pump 30 is disposed below the feed pump 32. With this configuration, the oil OL in the oil pan 14 can be efficiently collected.

[0045] 1, in this embodiment, the discharge port 32b of the feed pump 32 is disposed on the exhaust side where the main oil gallery 36 is disposed in the orthogonal direction PD. With this configuration, the pressure of the oil OL is high in the portion of the oil passage close to the discharge port 32b of the feed pump 32. Piston jetting can be performed from this high-pressure portion.

[0046] In this embodiment, as shown in Figure 3, the discharge port 30b of the scavenge pump 30 and the suction port 32a of the feed pump 32 are disposed on the intake side in the orthogonal direction PD. With this configuration, the discharge passage of the scavenge pump 30 and the suction passage of the feed pump 32 can be disposed on the intake side, which is relatively cool. This not only suppresses a temperature rise of the oil OL heading toward the oil tank 28, but also allows the oil OL to cool in the external oil tank 28, and further suppresses a temperature rise of the oil OL returning from the oil tank 28. As a result, the temperature of the oil OL supplied to the lubricated parts of the engine E can be lowered.

[0047] In this embodiment, as shown in Fig. 2, the oil pan 14 is attached to the bottom surface of the crankcase 4 with fastening members 15 such as bolts, and the scavenge pump 30 and the feed pump 32 are attached to the crankcase 4 with fastening members 35 (Fig. 3) such as bolts. With this configuration, the scavenge pump 30 and the feed pump 32 are attached to the sturdy crankcase 4, so that the pumps 30, 32 are stably supported.

[0048] The engine unit of the present disclosure is preferably mounted on mobile objects such as aircraft, vehicles, etc. The engine of the present disclosure is also preferably mounted on off-road vehicles such as four-wheel buggies (all-terrain vehicles), utility vehicles, and recreational vehicles.

[0049] The present disclosure is not limited to the above embodiments, and various additions, modifications, and deletions are possible without departing from the spirit and scope of the present disclosure. For example, the engine unit of the above embodiment can also be applied to saddle-type vehicles such as motorcycles, tricycles, and four-wheeled buggies (all-terrain vehicles). The engine unit may be used in an outboard motor or as a propulsion source for aircraft. Additionally, the engine unit may be used as a propulsion source for four-wheeled vehicles or small personal watercraft. The number of cylinders is not limited to six, and may be less than six, or seven or more. The engine unit may be provided with a supercharger such as a turbocharger or a supercharger. Therefore, such configurations are also included within the scope of the present disclosure.

[0050] 2 Crankshaft 3 Piston 4 Crankcase 14 Oil pan (lubricant pan) 28 Oil tank (lubricant tank) 30 Scavenge pump 30a Scavenge pump suction port 30b Scavenge pump discharge port 30s Scavenge pump rotating shaft 32 Feed pump 32a Feed pump suction port 32b Feed pump discharge port 32s Feed pump rotating shaft E Engine EU Engine unit OL Oil (lubricant)

Claims

1. An engine unit comprising: a scavenge pump that sucks and discharges lubricating liquid from within a lubricating liquid pan of an engine; a lubricating liquid tank that stores the lubricating liquid discharged by the scavenge pump; and a feed pump that supplies the lubricating liquid drawn out from the lubricating liquid tank to lubricated parts of the engine, wherein the scavenge pump and the feed pump are disposed inside the lubricating liquid pan; the scavenge pump and the feed pump are trochoid pumps, the rotational axes of the scavenge pump and the feed pump are coaxial; and the offset of the pump rotational axis relative to the outer diameter of the scavenge pump and the feed pump is set in opposite directions.

2. An engine unit according to claim 1, wherein the suction port of the scavenge pump is located below the feed pump.

3. An engine unit according to claim 1 or 2, wherein the discharge port of the feed pump is located on the side where a piston jet that injects lubricating liquid onto the piston is located, in a direction perpendicular to both the axial direction of the crankshaft and the reciprocating direction of the piston.

4. An engine unit according to any one of claims 1 to 3, wherein the discharge port of the scavenge pump and the suction port of the feed pump are arranged on the side where the intake port is formed, in a direction perpendicular to both the axial direction of the crankshaft and the reciprocating direction of the piston.

5. An engine unit according to any one of claims 1 to 4, wherein the lubricating liquid pan is attached to the bottom surface of the crankcase of the engine, and the scavenge pump and the feed pump are attached to the crankcase.

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