Engine

Abstract

To provide an engine for preventing seizure of a bearing part 49a of a supercharger 49.SOLUTION: An engine having an auxiliary machine mounting base 36 mounted on an intake end side of a cylinder block 27 close to a rear, that is, one side in a longitudinal direction, includes an oil branch pipe 50 led out from a rear side of the auxiliary mounting base 36, a rear end wall crossing oil path 27b crossing an internal of a rear end wall 27a of the cylinder block 27, and a supercharger oil supply pipe 51 for supplying engine oil 37 to a bearing part 49a of a supercharger 49. The engine oil 37 in the auxiliary machine mounting base 36 is supplied to the bearing part 49a of the supercharger 49 via the oil branch pipe 50, the rear end wall crossing oil path 27b, and the supercharger oil supply pipe 51 in sequence.SELECTED DRAWING: Figure 9

Description

Technical Field

[0001] The present invention relates to an engine, and more particularly to an engine in which seizure of a bearing portion of a supercharger is prevented.

Background Art

[0002] Conventionally, there is an engine that supplies engine oil to a bearing portion of a supercharger. (See, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] <<Problems>> There is a risk that the bearing portion of the supercharger may seize. In the engine of Patent Document 1, engine oil purified in the engine is supplied to the bearing portion of the supercharger via a supercharger oil supply pipe. However, the supercharger oil supply pipe is led out from the front end portion on the intake side of the engine and is composed of an engine external assembly pipe that surrounds the outer periphery of the engine along the intake side of the engine, the rear end side of the engine, and the exhaust side of the engine. If the oil supply at engine startup is delayed due to the long oil supply path to the supercharger, there is a risk that the bearing portion of the supercharger may seize.

[0005] An object of the present invention is to provide an engine in which seizure of a bearing portion of a supercharger is prevented.

Means for Solving the Problems

[0006] The main configuration of the present invention is as follows. As shown in Fig. 5, with one side in the front-rear direction being the rear, an auxiliary machine mounting base (36) is attached to the rear side of the intake end of the cylinder block (27). As shown in Fig. 9, an oil branch pipe (50) led out from the rear side of the auxiliary machine mounting base (36), a rear end wall transverse oil passage (27b) crossing inside the rear end wall (27a) of the cylinder block (27), and a supercharger oil supply pipe (51) for supplying engine oil (37) to the bearing part (49a) of the supercharger (49) are provided. The engine oil (37) in the auxiliary machine mounting base (36) is configured to be supplied to the bearing part (49a) of the supercharger (49) through the oil branch pipe (50), the rear end wall transverse oil passage (27b), and the supercharger oil supply pipe (51) in sequence. The engine is characterized by this.

[0007] The present invention has the following effects. 《Effect》 Seizure of the bearing part (49a) of the supercharger (49) is prevented. In this engine, since the engine oil (37) is supplied from the auxiliary machine mounting base (36) to the bearing part (49a) of the supercharger (49) through the shortest path, at the start of the engine, the engine oil (37) is supplied to the bearing part (49a) of the supercharger (49) in a short time, and its seizure is prevented. 《Effect》 Seizure of the bearing part (49a) of the supercharger (49) is also prevented during cold start. In this engine, during cold start of the engine when the viscosity of the engine oil (37) becomes high, the engine oil (37) passing through the rear end wall transverse oil passage (27b) crossing inside the rear end wall (27a) of the cylinder block (27) immediately after start is warmed by the combustion heat of the engine and becomes low-viscosity. Since the engine oil (37) is supplied to the bearing part (49a) of the supercharger (49) without delay, seizure of the bearing part (49a) of the supercharger (49) is also prevented during cold start.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

BEST MODE FOR CARRYING OUT THE INVENTION

[0009] FIGS. 1 to 10 are diagrams for explaining a water-cooled engine according to an embodiment of the invention. In this embodiment, a vertical four-cycle in-line four-cylinder diesel engine will be described.

[0010] As shown in FIG. 10, this engine includes a cylinder block (27), a cylinder head (17) assembled on the upper part of the cylinder block (27), a head cover (17d) assembled on the upper part of the cylinder head (17), a crankshaft (13) housed in the crankcase (27c) of the cylinder block (27), a gear case (53) assembled on the front side of the cylinder block (27) with the erection direction of the crankshaft (13) being the front-rear direction, one side of the front-rear direction being the front and the other being the rear, an engine cooling fan (14) arranged on the front side of the gear case (53), and a flywheel (54) attached to the crankshaft (13) on the rear side of the cylinder block (27). The engine cooling fan (14) blows the engine cooling air (15) backward.

[0011] As shown in FIG. 3(B), when viewed in a direction parallel to the cylinder central axis line (16a), with the width direction of the cylinder head (17) orthogonal to the front-rear direction being the lateral direction, as shown in FIGS. 8 and 9, an intake manifold (55) is provided on one lateral side of the cylinder head (17), and an exhaust manifold (56) is provided on the other side. This engine includes an intake device, a fuel supply device, an exhaust device, a valve operating device, an interlocking shaft, a lubrication device, and a water cooling device.

[0012] As shown in FIG. 10, the intake device includes an air cleaner (57), an air compressor (49b) of a supercharger (49) attached to the upper part of the exhaust manifold (56), a supercharging pipe (49c), and the intake manifold (55) shown in FIG. 5. The air purified by the air cleaner (57) shown in FIG. 10 is compressed by the air compressor (49b) and supercharged from the supercharging pipe (49c) into the intake manifold (55) shown in FIG. 5.

[0013] As shown in FIG. 5, the fuel supply device includes a fuel tank (58), a fuel supply pump (59), a common rail (60), a fuel injector (61), and an engine ECU (62). The electromagnetic valve of the fuel injector (61) is electrically connected to the engine ECU (62). The electromagnetic valve is opened for a predetermined time at a predetermined timing under the control of the engine ECU (62), and fuel (73) with a predetermined injection amount is injected from the fuel injector (61) into each cylinder (16) at a predetermined injection timing. The fuel (73) is light oil. ECU is an abbreviation for electronic control unit and is a microcomputer. The injection timing is set by the crank angle, and the crank angle is detected based on a pulse signal associated with the engine rotation formed by an electromagnetic pickup (63) electrically connected to the engine ECU (62).

[0014] As shown in FIG. 10, the exhaust device includes an exhaust manifold (56), an exhaust turbine (49d) of the supercharger (49), and an exhaust treatment device (74). The exhaust gas discharged from the exhaust manifold (56) is processed by a DOC and a DPF (not shown) in the exhaust treatment device (74) after driving the exhaust turbine (49d). DOC is an abbreviation for diesel oxidation catalyst, and DPF is an abbreviation for diesel particulate filter.

[0015] As shown in FIGS. 8 and 9, the valve operating device includes a valve operating camshaft (64) and an intake / exhaust valve (not shown) driven by the valve operating camshaft (64). The valve operating camshaft (64) is interlocked with the crankshaft (13) via a timing transmission gear train (not shown). The crankshaft (13) also interlocks a pair of left and right secondary balance shafts (65)(65) via a timing transmission gear train.

[0016] As shown in Fig. 5, the lubrication device includes an oil pan (34), an oil strainer (66), an oil pump (35), an accessory mounting base (36), a base oil supply passage (38) for supplying engine oil (37) from the oil pump (35) to the accessory mounting base (36), a crankshaft oil supply passage (39) for supplying engine oil (37) from the base oil supply passage (38) to the bearing portion (13a) of the crankshaft (13), and as shown in Fig. 8, a pair of balancer shaft oil supply passages (67) for supplying engine oil (37) to the bearing portions (65a) of the pair of left and right secondary balancer shafts (65)(65) via the crankshaft oil supply passage (39), and a camshaft oil supply passage (68) for supplying engine oil (37) from the bearing portion (65a) of the secondary balancer shaft (65) on the exhaust end side to the bearing portion (64a) of the valve camshaft (64). An oil cooler (19) and an oil filter (44) are attached to the accessory mounting base (36). The oil cooler (19) is disposed at a position higher than that of the oil filter (44).

[0017] As shown in Fig. 1, the water cooling device includes an engine cooling water circulation path (1). The engine cooling water circulation path (1) includes a water jacket (2) in the engine, a valve housing case (4) accommodating a thermostat valve (3), a main water passage (5), a radiator (7), a water pump (8), and a bypass water passage (6).

[0018] When the thermostat valve (3) closes during engine operation when the water temperature of the engine cooling water in the water jacket (2) is lower than a predetermined temperature, all of the engine cooling water (9) in the water jacket (2) bypasses the radiator (7) and returns to the water jacket (2) via the valve housing case (4), the bypass water passage (6), and the water pump (8) in that order. During engine operation, when the thermostat valve (3) opens due to the engine coolant (9) in the water jacket (2) having a temperature higher than a predetermined temperature, most of the engine coolant (9) in the water jacket (2) returns to the water jacket (2) via the valve housing case (4), the main water passage (5), the radiator (7), and the water pump (8) in sequence. At the same time, a part of the engine coolant (9) in the water jacket (2) bypasses the radiator (7) and returns to the water jacket (2) via the valve housing case (4), the bypass water passage (6), and the water pump (8) in sequence. That is, as shown in FIG. 1, during engine operation, this engine is configured such that a predetermined amount of the engine coolant (9) in the water jacket (2) bypasses the radiator (7) and returns to the water jacket (2) via the valve housing case (4), the bypass water passage (6), and the water pump (8) in sequence by the pumping force of the water pump (8).

[0019] As shown in FIG. 1, this engine includes an air bleeding passage (10) that is led out horizontally or in an upward direction from the upper part of the impeller chamber (8a) of the water pump (8) and reaches the bypass water passage (6), and an air passage portion (3a) that allows air to pass from the upstream side to the downstream side of the thermostat valve (3). During the water supply of the engine coolant (9) from the water supply port (7a) of the radiator (7) performed during engine stoppage, the air (11) that attempts to accumulate in the upper part of the impeller chamber (8a) of the water pump (8) is pushed out from the upper part of the impeller chamber (8a) through the air bleeding passage (10) into the bypass water passage (6) due to the rise in the water level of the coolant circulation path (1). And it is configured to be pushed out from the water supply port (7a) of the radiator (7) via the air passage portion (3a) and the main water passage (5) in sequence from the bypass water passage (6).

[0020] In this engine, during the supply of engine cooling water (9), as the water level in the cooling water circulation path (1) rises, air (11) that tends to accumulate in the upper part of the impeller chamber (8a) of the water pump (8) is pushed out from the water inlet (7a) of the radiator (7). Since it is difficult for the air (11) to remain in the engine cooling water circulation path (1) during engine operation, it is difficult for the cooling performance to decrease due to the circulation of the air (11) in the cooling water circulation path (1), and the cooling performance of the engine is enhanced. Also, in this engine, during engine operation, since it is difficult for the air (11) to circulate in the cooling water circulation path (1), damage to the cooling water circulation path (1) due to cavitation is less likely to occur.

[0021] As shown in FIG. 1, in this embodiment, the air bleeding passage (10) is formed by a through-hole that is led out horizontally from the impeller chamber (8a) and reaches the bypass water passage (6), and the air passage portion (3a) is formed in the thermostat valve (3). However, the present invention is not limited to this. The air bleeding passage (10) may be led out obliquely upward or vertically upward from the impeller chamber (8a), and the air passage portion (3a) may be provided in the valve housing case (4). Note that the pump housing (8b) of the water pump (8), the end portion of the water passage wall (6a) of the bypass water passage (6), and the passage wall (10a) of the air bleeding passage (10) installed therebetween are integrally formed of a continuous metal material, and a through-hole air bleeding passage (10) is formed in the passage wall (10a) of the air bleeding passage (10).

[0022] As shown in FIG. 1, this engine includes a reserve tank (12) connected to the water inlet (7a) of the radiator (7). In this engine, since it is difficult for air (11) to remain in the cooling water circulation path (1), the amount of engine cooling water (9) in the reserve tank (12) exchanged with the air (11) is reduced, and the replenishment frequency of the engine cooling water (9) to the reserve tank (12) can be decreased.

[0023] As shown in Fig. 1, the radiator (7) includes an upper tank (7b), a lower tank (7c), and horizontally arranged vertical heat dissipation tubes (7d) therebetween. The upper tank (7b) is connected to the valve housing case (4) via the main water passage (5), and the lower tank (7c) is connected to the water pump (8) via the return water passage (72). The water inlet (7a) is provided in the upper tank (7b) and covered with a radiator cap (7e).

[0024] As shown in Fig. 1, the radiator cap (7e) is provided with a valve mechanism (7f). During engine operation, as the temperature rises, the volume of the engine cooling water (9) in the cooling water circulation path (1) expands, and when the internal pressure of the cooling water circulation path (1) increases, the main pressure valve of the valve mechanism (7f) opens, and a part of the engine cooling water (9) in the cooling water circulation path (1) overflows and accumulates in the reserve tank (12). After the engine stops and the temperature drops, when the internal pressure of the cooling water circulation path (1) decreases, the negative pressure valve of the valve mechanism (7f) opens, and a part of the engine cooling water (9) accumulated in the reserve tank (12) is drawn back into the cooling water circulation path (1).

[0025] As shown in Figs. 3(A) and (B), the water jacket (2) includes a cylinder jacket (2a) around the cylinder (16) and a head jacket (2b) in the cylinder head (17). As shown in Fig. 3(A), the cylinder jacket (2a) has a jacket inlet (2c) at the front end. As shown in Fig. 3(B), the head jacket (2b) has a jacket outlet (2d) at the front end. Between the cylinder jacket (2a) and the head jacket (2b), a plurality of water floating upper ports (18) opened on the peripheral side of each cylinder (16) are provided. Through the plurality of water floating upper ports (18), the engine cooling water (9) floats from the cylinder jacket (2a) to the head jacket (2b). The head jacket (2b) has a rear end side jacket portion (2ba) facing the rear end side water floating upper port (18a) located in the rear end side head portion (17a) of the cylinder head (17) among the plurality of water floating upper ports (18). As shown in FIG. 2, this engine includes a water-cooled oil cooler (19), a cooler water supply pipe (20) from the head jacket (2b) to the oil cooler (19), and a cooler drain pipe (21) from the oil cooler (19) to the water pump (8). The cooler water supply pipe (20) is led out from the rear-end side jacket portion (2ba).

[0026] In this engine, since the suction force of the water pump (8) acts on the rear-end side jacket portion (2ba) through the cooler drain pipe (21), the oil cooler (19), and the cooler water supply pipe (20) in sequence, a large amount of engine cooling water (9) is sucked up from the rear-end side water floating upper port (18a) to the rear-end side jacket portion (2ba), and the cooling performance of the rear-end side head portion (17a) where the engine cooling water (9) is originally difficult to float is improved. Also, in this engine, since a large amount of engine cooling water (9) floats from the rear-end side water floating upper port (18a) to the rear-end side jacket portion (2ba), for this purpose, there is no need to reduce the passage cross-sectional area of the other water floating upper ports (18), the passage resistance of the cooling water circulation path (1) can be reduced, and the cooling performance of the engine is enhanced.

[0027] As shown in FIG. 2, the cooler water supply pipe (20) is led out from the upper-end side portion (2bb) of the rear-end side jacket portion (2ba). In this engine, when the engine is inclined downward in the front, air (11) and water vapor that tend to accumulate in the upper-end side portion (2bb) of the rear-end side jacket portion (2ba) are sucked out through the cooler water supply pipe (20), so it is difficult for air (11) and water vapor to stagnate in the rear-end side jacket portion (2ba), and the cooling performance of the rear-end side head portion (17a) is enhanced.

[0028] As shown in FIG. 3(B), among the both lateral sides, with the inlet (22a) side of the intake port (22) being the intake end side and the outlet (32a) side of the exhaust port (32) being the exhaust end side, the cooler water supply pipe (20) is led out from the intake end side portion (2bc) of the rear-end side jacket portion (2ba). In this engine, since the relatively cold engine cooling water (9) in the intake end side portion (2bc) of the rear end side jacket portion (2ba) is supplied from the cooler water supply pipe (20) to the oil cooler (19), the cooling performance of the oil cooler (19) is enhanced.

[0029] As shown in FIG. 3(B), the head jacket (2b) includes, among a plurality of upper inter-bore water passages (23) located above the cylinder bores, a rear-end side upper inter-bore water passage (23a) closer to the rear end of the cylinder head (17), among a plurality of water floating upper ports (18), a rear-end side water floating upper port (18b) that supplies the engine cooling water (9) to the rear-end side upper inter-bore water passage (23a), a rear-end side jacket portion (2bd) facing the rear-end side water floating upper port (18b), and a partition wall (24). The rear-end side jacket portion (2bd) is disposed on the front side of the rear-end side jacket portion (2ba), and the partition wall (24) is disposed between the rear-end side jacket portion (2bd) and the rear-end side jacket portion (2ba). In this engine, the engine cooling water (9) that has risen from the rear-end side water floating upper port (18b) to the rear-end side jacket portion (2bd) is blocked by the partition wall (24) and is supplied to the rear-end side upper inter-bore water passage (23a) without being sucked into the cooler water supply pipe (20) led out from the rear-end side jacket portion (2ba). Therefore, the cooling performance of the rear-end side head portion (17b) of the cylinder head (17) is enhanced. As shown in FIG. 3(B), the rear-end side upper inter-bore water passage (23a) is located between the rearmost cylinder (16) and the cylinder (16) in front of it.

[0030] As shown in FIG. 3(C), in this engine, the partition wall (24) connects the lower peripheral wall (22b) of the intake port (22) and the head bottom wall (17c) of the cylinder head (17). In this engine, since the heat of the head bottom wall (17c) is radiated to the lower peripheral wall (22b) of the intake port (22) through the partition wall (24), the cooling performance of the head bottom wall (17c) is enhanced. In this engine, the rigidity of the head bottom wall (17c) is enhanced by the partition wall (24).

[0031] As shown in FIG. 3(B), the cylinder head (17) includes an upper inter-bore water passage (23) located above the cylinder bores, and head bolt bosses (25) arranged on both lateral sides of the upper inter-bore water passage (23) as shown in FIG. 4(A). The head bolt bosses (25) include head bolts (26) inserted therein. The cylinder head (17) and the cylinder block (27) are fastened with a head gasket (28) sandwiched therebetween by the fastening force of the head bolts (26). The cylinder head (17) includes a reinforcing wall (29) along one of the pair of head bolt bosses (25)(25) arranged on both lateral sides of the upper inter-bore water passage (23), and a reinforcing rib (30) along the other head bolt boss (25). The reinforcing wall (29) connects the water passage bottom wall (23b) of the upper inter-bore water passage (23) and the jacket ceiling wall (2be) of the head jacket (2b). The reinforcing rib (30) bulges from the water passage bottom wall (23b) toward the jacket ceiling wall (2be).

[0032] In this engine, since the heat of the water passage bottom wall (23b) is dissipated to the engine cooling water (9) passing through the upper inter-bore water passage (23) from the reinforcing wall (29) and the reinforcing rib (30), the cooling performance of the water passage bottom wall (23b) is enhanced. Also, in this engine, since the fastening force of the head bolts (26) is transmitted to the water passage bottom wall (23b) via the reinforcing wall (29) and the reinforcing rib (30), the sealing performance of the head gasket (28) is enhanced. Also, in this engine, the rigidity of the water passage bottom wall (23b) is enhanced by the reinforcing wall (29) and the reinforcing rib (30).

[0033] As shown in FIG. 4(B), the reinforcing wall (29) is connected to the peripheral wall (22c) of the intake port (22). In this engine, since the heat of the water passage bottom wall (23b) is dissipated to the peripheral wall (22c) of the intake port (22) via the reinforcing wall (29), the cooling performance of the water passage bottom wall (23b) is enhanced. In this engine, the rigidity of the water passage bottom wall (23b) is increased by a reinforcing wall (29) connected to the peripheral wall (22c) of the intake port (22).

[0034] As shown in FIGS. 4(A) and 4(C), the reinforcing rib (30) is disposed on a water passage bottom wall portion (23c) on the exhaust end side of the water passage bottom wall (23b). In this engine, the heat of the water passage bottom wall portion (23c) on the exhaust end side, which is prone to overheating, is conducted to the reinforcing rib (30) and dissipated to the engine cooling water (9) that passes through a large amount above the reinforcing rib (30). Therefore, the cooling performance of the water passage bottom wall portion (23c) on the exhaust end side is enhanced.

[0035] As shown in FIG. 4(A), the raised end face (30a) of the reinforcing rib (30) slopes downward from the head bolt boss (25) along the reinforcing rib (30) toward the reinforcing wall (29) side. For this reason, the tightening force of the head bolt (26) is transmitted to the water passage bottom wall portion (23c) on the exhaust end side via the reinforcing rib (30), and the heat of the water passage bottom wall portion (23c) on the exhaust end side is dissipated to the large amount of engine cooling water (9) flowing above the reinforcing rib (30) from the inclined and wide raised end face (30a) of the reinforcing rib (30), enhancing the cooling performance of the water passage bottom wall portion (23c) on the exhaust end side.

[0036] As shown in FIG. 4(A), this engine is provided with a pair of water lifting holes (31)(31) for lifting the engine cooling water (9) from the cylinder jacket (2a) to the head jacket (2b) on both lateral sides in the transverse direction of the water passage bottom wall (23b) of the between-bore upper water passage (23). Among the pair of water lifting holes (31)(31), the water lifting hole (31) on the exhaust end side is defined as the exhaust end side water lifting hole (31a), and the water lifting hole (31) on the intake end side is defined as the intake end side water lifting hole (31b). As shown in FIGS. 4(A) and 4(C), the exhaust end side water lifting hole (31a) is provided inside the reinforcing rib (30). As shown in FIGS. 4(A) and 4(B), the intake end side water lifting hole (31b) is provided inside the reinforcing wall (29). As shown in FIG. 4(B), the water lifting hole outlet (31ba) of the intake end side water lifting hole (31b) is directed toward the exhaust port peripheral wall (32b). As shown in FIG. 4(B), in this engine, since the engine cooling water (9) flowing out from the water floating hole outlet (31ba) of the intake end side water floating hole (31b) is directed toward the exhaust port peripheral wall (32b), the cooling performance of the exhaust port peripheral wall (32b) is enhanced.

[0037] As shown in FIG. 4(A), the cylinder jacket (2a) includes an inter-bore water passage (33) provided between adjacent cylinder bores, a jacket portion (2aa) on the intake end side, and a jacket portion (2ab) on the exhaust end side, and the engine cooling water (9) is sent from the jacket portion (2aa) on the intake end side to the jacket portion (2ab) on the exhaust end side through the inter-bore water passage (33). The inter-bore water passage (33) includes a first transverse water passage (33c) provided between the inter-bore ceiling wall (33a) and the first transverse wall (33b) directly below it, and a second transverse water passage (33e) provided between the first transverse wall (33b) and the second transverse wall (33d) directly below it. Since the intake end side wall portion (33ba) of the first transverse wall (33b) slopes downward toward the jacket portion (2aa) on the intake end side, the lower part (33ca) of the inlet of the first transverse water passage (33c) slopes downward toward the jacket portion (2aa) on the intake end side, and the upper part (33ea) of the inlet of the second transverse water passage (33e) is configured to slope downward toward the jacket portion (2aa) on the intake end side.

[0038] In this engine, as shown in FIG. 3(A), the jacket inlet (2c) on the front end side of the cylinder jacket (2a) faces the lateral center portion of the front surface of the front end side cylinder (16), the passage cross-sectional area of the jacket portion (2aa) on the intake end side is wider than the passage cross-sectional area of the jacket portion (2ab) on the exhaust side, and as shown in FIG. 3(B), since the jacket outlet (2d) on the front end side of the head jacket (2b) is arranged offset toward the exhaust end side, the engine cooling water (9) is sent from the jacket portion (2aa) on the intake end side to the jacket portion (2ab) on the exhaust end side through the inter-bore water passage (33).

[0039] In this engine, the low-temperature engine cooling water (9) located at the lower side of the jacket portion (2aa) on the intake end side is introduced upward along the inclinations of the lower part of the inlet of the first transverse water passage (33c) and the upper part of the inlet of the second transverse water passage (33e), so that the cooling performance between the cylinder bores is enhanced.

[0040] As shown in Fig. 4(A), the inter-bore water passage (33) includes a third transverse water passage (33g) provided between the second transverse wall (33d) and the third transverse wall (33f) directly below it. Since the intake end side wall portion (33da) of the second transverse wall (33d) slopes downward toward the intake side jacket portion (2aa), the lower part of the inlet of the second transverse water passage (33e) slopes downward toward the intake end side jacket portion (2aa), and the upper part of the inlet of the third transverse water passage (33g) is configured to slope downward toward the intake end side jacket portion (2aa). In this engine, the low-temperature engine cooling water (9) located at the lower side of the jacket portion (2aa) on the intake end side is introduced upward along the inclinations of the lower part of the inlet of the second transverse water passage (33e) and the upper part of the inlet of the third transverse water passage (33g), so that the cooling performance between the cylinder bores is enhanced.

[0041] As shown in Fig. 4(A), in this engine, the exhaust end side water floating hole (31a) has a larger minimum passage cross-sectional area than the intake end side water floating hole (31b). In this engine, the flow of the engine cooling water (9) introduced from the jacket portion (2aa) on the intake end side to the exhaust end side water floating hole (31a) through the inter-bore water passage (33) is promoted, so that the cooling performance between the cylinder bores is enhanced. The inter-bore water passage (33) includes a fourth transverse water passage (33k) provided between the third transverse wall (33f) and the fourth transverse wall (33h) directly below it. The fourth transverse water passage (33k) is formed in a horizontal direction.

[0042] As shown in Fig. 5, this engine includes an oil pan (34), an oil pump (35), an accessory mounting base (36) with an oil cooler (19) attached thereto, a base oil supply passage (38) for supplying engine oil (37) in the oil pan (34) from the oil pump (35) to the accessory mounting base (36), and a crankshaft oil supply passage (39) for supplying the engine oil (37) cooled by the oil cooler (19) from the accessory mounting base (36) to the bearing portion (13a) of the crankshaft (13).

[0043] As shown in Fig. 6(B), in this engine, the accessory mounting base (36) includes an oil cooler oil supply port (40), an oil cooler oil supply passage (40a) led out from the oil cooler oil supply port (40), an oil cooler oil drain port (41), and an oil cooler oil drain passage (41a) led out from the oil cooler oil drain port (41). Of the oil cooler oil supply port (40) and the oil cooler oil drain port (41) having a height difference, the higher one is defined as the cooler high - level port (42), and the lower one is defined as the cooler low - level port (43). Of the oil cooler oil supply passage (40a) and the oil cooler oil drain passage (41a), the one led out from the cooler low - level port (43) is defined as the cooler low - level port oil passage (43a). The cooler low - level port oil passage (43a) is led upward to a height equal to or higher than the height of the lower edge (42a) of the cooler high - level port (42). The height equal to or higher than the height of the lower edge (42a) of the cooler high - level port (42) means a height equal to or higher than the height of the lower edge (42a) of the cooler high - level port (42).

[0044] In this engine, during engine stoppage, the engine oil (37) in the oil cooler (19) remains at least up to the height of the lower edge (42a) of the cooler high - level port (42). Therefore, when the engine is restarted, the engine oil (37) is supplied to the bearing portion (13a) of the crankshaft (13) via the crankshaft oil supply passage (39) in a short time, and seizure thereof is prevented.

[0045] As shown in FIG. 6(B), in this engine, among the oil cooler supply oil passage (40a) and the oil cooler drain oil passage (41a), the one led out from the cooler upper port (42) is defined as the cooler upper port oil passage (42c). When viewed in a direction parallel to the lateral direction, the cooler upper port oil passage (42c) is led out downward from the cooler upper port (42). During engine stoppage, the engine oil (37) in the oil cooler (19) flows down to the oil pan (34) side in sequence through the cooler upper port (42), the cooler upper port oil passage (42c), the filter lower port oil passage (48a), the oil filter (44), and the base supply oil passage (38). Therefore, it only remains up to the height of the lower edge (42a) of the cooler upper port (42).

[0046] The cooler upper port oil passage (42c) shown in FIG. 6(B) can be led out upward from the cooler upper port (42) when viewed in a direction parallel to the lateral direction, and can also be led out upward to a height equal to or higher than the height of the lower edge (42a) of the cooler upper port (42) and the cooler lower port oil passage (43a). In this case, during engine stoppage, the engine oil (37) in the oil cooler (19) can remain up to the height of the lower edge (42a) of the cooler upper port (42) or up to the height of the lower edge of the upward leading end of the cooler lower port oil passage (43a) that exceeds this height.

[0047] As shown in FIGS. 6(B) and (C), the cooler upper port (42) is provided in the pipe base end portion (42ba) inserted into the accessory mounting base (36) among the horizontally oriented pipes (42b) oriented in the lateral direction. As shown in FIG. 6(B), when viewed in a direction parallel to the lateral direction, after the cooler lower port oil passage (43a) is led out upward from the cooler lower port (43), it is led out downward to the oil passage inlet (39a) of the crankshaft supply oil passage (39).

[0048] As shown in FIG. 6(B), the oil cooler supply port (40) is the cooler upper port (42), the oil cooler drain port (41) is the cooler lower port (43), and the oil cooler drain oil passage (41a) is the cooler lower port oil passage (43a). During engine operation, the engine oil (37) passing through the oil cooler (19) by the pumping force of the oil pump (35) smoothly descends in the oil cooler (19) while increasing its specific gravity due to the cooling of the oil cooler (19), so the pumping load on the oil pump (35) can be reduced.

[0049] As shown in FIGS. 6(C) to (F), the oil cooler (19) is configured by alternately overlapping an oil passage layer (19b) through which the engine oil (37) passes and a water passage layer (19c) through which the engine cooling water (9) passes. As shown in FIG. 6(E), an oil partition wall (19ba) is provided in the oil passage layer (19b), and as shown in FIG. 6(F), a water partition wall (19ca) is provided in the water passage layer (19c). In the oil passage layer (19b), the engine oil (37) introduced from the upper rear oil cooler oil supply port (40) reverses downward and rearward in front of the oil partition wall (19ba) and is discharged from the lower rear oil cooler oil drain port (41). In the water passage layer (19c), the engine cooling water (9) introduced from the lower front oil cooler water supply port (70) reverses upward and forward behind the water partition wall (19ca) and is discharged from the upper front oil cooler water drain port (71).

[0050] As shown in FIG. 5, this engine is equipped with an oil filter (44) attached to the accessory mounting base (36), and the engine oil (37) supplied to the accessory mounting base (36) is purified by the oil filter (44) and supplied to the oil cooler (19). As shown in FIGS. 6(B) and (C), the accessory mounting base (36) includes an oil filter oil supply port (45), an oil filter oil supply passage (45a) led out from the oil filter oil supply port (45), an oil filter oil drain port (46), and an oil filter oil drain passage (46a) led out from the oil filter oil drain port (46). Of the oil filter fuel inlet (45) and the oil filter drain outlet (46) with a level difference, the higher one is defined as the filter high point port (47), and the lower one is defined as the filter low point port (48). Among the oil filter fuel supply line (45a) and the oil filter drain line (46a), the one derived from the filter low point port (48) is defined as the filter low point port oil line (48a). The filter low point port oil line (48a) is led upward to a height equal to or higher than the height of the lower edge (47a) of the filter high point port (47). The height equal to or higher than the height of the lower edge (47a) of the filter high point port (47) means the same height as or a higher height than the height of the lower edge (47a) of the filter high point port (47).

[0051] As shown in FIG. 6(C), in this engine, among the oil filter fuel supply line (45a) and the oil filter drain line (46a), the one derived from the filter high point port (47) is defined as the filter high point port oil line (47b). The filter high point port oil line (47b) is led out horizontally from the filter high point port (47). When the engine is stopped, the engine oil (37) in the oil filter (44) flows down to the oil pan (34) side sequentially through the filter high point port (47), the filter high point port oil line (47b), and the base fuel supply line (38), and only remains up to the height of the lower edge (47a) of the filter high point port (47).

[0052] The filter high point port oil line (47b) may be led upward from the filter high point port (47) when viewed in a direction parallel to the horizontal direction. In this case, when the engine is stopped, the engine oil (37) in the oil filter (44) can remain up to the height of the lower edge of the upward leading end of the filter high point port oil line (47b) that is the same as or exceeds the height of the lower edge (47a) of the filter high point port (47).

[0053] As shown in FIG. 6(C), the filter high point port (47) is provided at the oil outlet (47c) of the horizontal filter high point port oil line (47b) directed in the lateral direction of the accessory mounting base (36). As shown in FIG. 6(C), the filter high point port oil line (47b) is connected to the oil outlet (38a) of the base fuel supply line (38). As shown in FIG. 6(B), the filter lower outlet oil passage (48a) is connected to the upward cooler upper outlet oil passage (42c) after being led out upward from the filter lower outlet (48).

[0054] In this engine, during engine stop, the engine oil (37) in the oil filter (44) remains at least up to the height of the lower edge (47a) of the filter upper outlet (47). Therefore, when the engine is restarted, the engine oil (37) is supplied to the bearing portion (13a) of the crankshaft (13) via the crankshaft oil supply passage (39) in a short time, and its seizure is prevented.

[0055] As shown in FIG. 6(B), the oil filter oil supply port (45) is the filter upper outlet (47), the oil filter oil drain port (46) is the filter lower outlet (48), and the oil filter oil drain passage (46a) is the filter lower outlet oil passage (48a). In this engine, during engine operation, the engine oil (37) passing through the oil filter (44) by the pumping force of the oil pump (35) descends by its own weight inside the oil filter (44), so the burden of pumping by the oil pump (35) can be reduced.

[0056] Modifications of the accessory mounting base (36) shown in FIGS. 7(A) and (B) are as follows. Both the oil cooler oil supply passage (40a) and the oil cooler oil drain passage (41a) of the accessory mounting base (36) are led out upward to a height equal to or higher than the height of the uppermost part (19a) inside the cooler of the oil cooler (19).

[0057] The height equal to or higher than the height of the uppermost part (19a) inside the cooler of the oil cooler (19) means a height equal to or higher than the height of the uppermost part (19a) inside the cooler of the oil cooler (19).

[0058] In this engine, while the engine is stopped, the engine oil (37) in the oil cooler (19) remains filled in the oil cooler (19). Therefore, when the engine is restarted, the engine oil (37) is supplied to the bearing portion (13a) of the crankshaft (13) via the crankshaft oil supply passage (39) in a short time, preventing seizure thereof.

[0059] As shown in FIGS. 7(A) and (B), both the oil filter oil supply passage (45a) and the oil filter oil drain passage (46a) are led upward to a height equal to or higher than the height of the uppermost part (44a) inside the filter of the oil filter (44).

[0060] In this engine, while the engine is stopped, the engine oil (37) in the oil filter (44) remains filled in the oil filter (44). Therefore, when the engine is restarted, the engine oil (37) is supplied to the bearing portion (13a) of the crankshaft (13) via the crankshaft oil supply passage (39) in a short time, preventing seizure thereof.

[0061] Other configurations of the modification of the accessory mounting base (36) shown in FIGS. 7(A) and (B) are the same as the basic example of the accessory mounting base (36) shown in FIGS. 6(A) to (F). In FIGS. 7(A) and (B), the same elements as those in FIGS. 6(A) to (F) are denoted by the same reference numerals.

[0062] As shown in FIG. 5, in this engine, the accessory mounting base (36) is attached to the rear side of the intake end side of the cylinder block (27). As shown in FIG. 9, an oil branch pipe (50) led out from the rear side of the accessory mounting base (36), a rear end wall transverse oil passage (27b) crossing inside the rear end wall (27a) of the cylinder block (27), and a supercharger oil supply pipe (51) for supplying engine oil (37) to the bearing portion (49a) of the supercharger (49) are provided. The engine oil (37) in the accessory mounting base (36) is configured to be supplied to the bearing portion (49a) of the supercharger (49) through the oil branch pipe (50), the rear end wall transverse oil passage (27b), and the supercharger oil supply pipe (51) in this order.

[0063] In this engine, engine oil (37) is supplied from the accessory mounting base (36) to the bearing portion (49a) of the supercharger (49) along the shortest path. Therefore, at engine startup, the engine oil (37) is supplied to the bearing portion (49a) of the supercharger (49) in a short time, preventing seizure thereof. Also, in this engine, at cold startup of the engine when the viscosity of the engine oil (37) increases, the engine oil (37) passing through the rear end wall transverse oil passage (27b) that traverses inside the rear end wall (27a) of the cylinder block (27) immediately after startup is heated by the combustion heat of the engine, becoming low in viscosity. Since the engine oil (37) is supplied to the bearing portion (49a) of the supercharger (49) without delay, seizure of the bearing portion (49a) of the supercharger (49) is also prevented at cold startup.

[0064] As shown in FIGS. 8 to 10, in this engine, a supercharger drain pipe (69) is led out from the bearing portion (49a) of the supercharger (49), and the engine oil (37) that has lubricated the bearing portion (49a) of the supercharger (49) returns to the oil pan (34) via the supercharger drain pipe (69). The oil branch pipe (50), the supercharger oil supply pipe (51), and the supercharger drain pipe (69) are all external engine assembly pipes, and the rear end wall transverse oil passage (27b) is an internal engine oil passage.

[0065] As shown in FIG. 6(B), engine oil (37) is branched from the oil cooler drain oil passage (41a) of the accessory mounting base (36) to the oil branch pipe (50). In this engine, since the engine oil (37) cooled by the oil cooler (19) is supplied to the bearing portion (49a) of the supercharger (49), seizure of the bearing portion (49a) of the supercharger (49) is prevented even when the engine is running at high speed where the rotational speed of the supercharger (49) increases.

[0066] The structure of the modified example of the oil branch pipe (50) shown in FIG. 7(C) is as follows. A check valve (52) shown in Fig. 7(D) is attached to the oil branch pipe (50) shown in Fig. 7(C) to prevent the backflow of engine oil (37) from the oil branch pipe (50) to the accessory mounting base (36). In this engine, during engine shutdown, the engine oil (37) in the oil branch pipe (50), the rear end wall transverse oil passage (27b), and the supercharger oil supply pipe (51) shown in Fig. 9 does not leak to the accessory mounting base (36) side. Therefore, when the engine is restarted, the engine oil (37) is supplied to the bearing portion (49a) of the supercharger (49) in a short time, preventing seizure of the bearing portion (49a) of the supercharger (49). Note that the oil branch pipe (50) shown in Fig. 9 is led out from the oil filter drain port (46) on the upstream side of the oil cooler (19) in the flow path.

[0067] A modification of the oil branch pipe (50) shown in Fig. 7(C) may be combined with the basic example of the accessory mounting base (36) shown in Fig. 6(B), or may also be combined with the modification example of the accessory mounting base (36) shown in Fig. 7(A).

Explanation of Reference Numerals

[0068] (13)…Crankshaft, (13a)…Bearing portion, (16)…Cylinder, (16a)…Cylinder central axis line, (22)…Intake port, (27)…Cylinder block, (27a)…Rear end wall, (27b)…Rear end wall transverse oil passage, (34)…Oil pan, (35)…Oil pump, (36)…Accessory mounting base, (37)…Engine oil, (38)…Base oil supply passage, (41a)…Oil cooler drain oil passage, (49)…Supercharger, (49a)…Bearing portion, (50)…Oil branch pipe, (51)…Supercharger oil supply pipe, (52)…Check valve.

Claims

1. In an engine comprising an oil pan (34), an oil pump (35), an accessory mounting base (36) to which an oil cooler (19) is attached, a base oil supply passage (38) for supplying engine oil (37) in the oil pan (34) from the oil pump (35) to the accessory mounting base (36), and a crankshaft oil supply passage (39) for supplying the engine oil (37) cooled by the oil cooler (19) from the accessory mounting base (36) to a bearing portion (13a) of a crankshaft (13), when looking at the installation direction of the crankshaft (13) in a direction parallel to the cylinder center axis (16a) with the front-rear direction as the front-rear direction, and taking the width direction of the engine perpendicular to the front-rear direction as the lateral direction, among both sides in the lateral direction, with the inlet end side of the intake port (22) as the intake end side and the outlet end side of the exhaust port (32) as the exhaust end side, the base oil supply passage (38) and the accessory mounting base (36) are arranged on the intake end side of the cylinder block (27), and a supercharger (49) is arranged on the exhaust end side of the cylinder head (17), with one side in the rear direction as the rear, the accessory mounting base (36) is attached to the rear side of the intake end side of the cylinder block (27), and an oil branch pipe (50) led out from the rear side of the accessory mounting base (36), a rear end wall transverse oil passage (27b) crossing inside the rear end wall (27a) of the cylinder block (27), and a supercharger oil supply pipe (51) for supplying the engine oil (37) to a bearing portion (49a) of the supercharger (49) are provided, and the engine oil (37) in the accessory mounting base (36) is configured to be supplied to the bearing portion (49a) of the supercharger (49) through the oil branch pipe (50), the rear end wall transverse oil passage (27b), and the supercharger oil supply pipe (51) in sequence. The engine is characterized by this.

2. In the engine according to Claim 1, the engine oil (37) is branched from an oil cooler drain passage (41a) of the accessory mounting base (36) to the oil branch pipe (50). The engine is characterized by this.

3. In the engine according to Claim 1 or Claim 2, a check valve (52) is attached to the oil branch pipe (50), and the backflow of the engine oil (37) from the oil branch pipe (50) to the accessory mounting base (36) is blocked. The engine is characterized by this.

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