engine

Abstract

To provide an engine that has high heat shielding properties of a heat shielding cover 4, and does not require removing a stud bolt 3c from an exhaust outlet flange 3b when attaching or detaching the heat shielding cover 4 to or from an exhaust manifold 3.SOLUTION: An upper heat shielding plate 4a has an upward raised part 4aa above a head flange portion 3d, where a portion of the upper heat shielding plate 4a is raised upward in a protruding manner. When a heat shielding cover 4 is detached from an exhaust manifold 3 to an anti-head side, or when the heat shielding cover 4 is attached to the exhaust manifold 3 from the anti-head side, an upper end wall 4ad of a raised heat shielding part 4aa is inclined downward toward the anti-head side, and the heat shielding cover 4 is slid laterally along a direction of the inclination, so that a tip part 3ca of a stud bolt 3e passes through an internal space 4ae of the raised heat shielding part 4aa.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an engine, and more particularly to an engine in which the heat shield cover has high heat insulation properties and in which it is not necessary to remove stud bolts from the exhaust outlet flange when attaching or detaching the heat shield cover to or from the exhaust manifold. [Background technology]

[0002] BACKGROUND ART Conventionally, there is an engine that is provided with an exhaust manifold and a heat insulating cover that covers the exhaust manifold (see, for example, Patent Document 1). In this engine, the portion of the exhaust manifold between the exhaust outlet flange and the head flange, which is sandwiched between the cylinder head, is exposed above the heat insulating cover. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2013-199880 A (see Figure 1) Summary of the Invention [Problem to be solved by the invention]

[0004] <Problem> The heat-shielding cover has poor heat-shielding properties. In the engine of Patent Document 1, the portion of the exhaust manifold between the head flanges is exposed above the heat shield cover, so the heat shield cover has poor heat insulation properties.

[0005] <<Prototype engine prior to the present invention>> In order to solve the above problems, the inventor of the present invention produced a prototype engine shown in FIGS. 14 to 17 prior to the present invention. In this prototype engine, the heat shield cover (4) is provided with upper and lower heat shield plates (4a) and (4b) and an anti-head side heat shield plate (4c) that cover the exhaust manifold (3) from the upper, lower, and anti-head side, and the anti-head side has an anti-head side cover opening (4d) that exposes the end face (3ba) of the exhaust outlet flange (3b) on the anti-head side, and a stud bolt (3c) protrudes from the end face (3ba) of the exhaust outlet flange (3b) on the anti-head side.

[0006] The portion of the exhaust manifold (3) sandwiched between the exhaust outlet flange (3b) and the cylinder head (2) is the head flange portion (3d), and the head flange portion (3d) is covered from above by the flat portion (4ag) of the upper heat shield plate (4a).

[0007] In this prototype engine, the portion 3d between the head flanges of the exhaust manifold 3 is not exposed upward, and the heat insulating cover 4 has high heat insulating properties. 13(A) to 13(F) are explanatory diagrams of the heat insulating cover 4 used in the prototype engine.

[0008] <<New Problems with the Prototype>> When attaching or detaching the heat insulating cover (4) to the exhaust manifold (3), it is necessary to remove the stud bolts (3c) from the exhaust outlet flange (3b). In this prototype engine, as shown in Figure 12(A), if the upper and lower heat shield plates (4a) and (4b) are moved closer to the head flange portion (3d) in order to prevent the head flange portion (3d) from being exposed from the anti-head side cover opening (4d), a new problem will arise. That is, as shown in Figures 12(A) to (D), when the heat shield cover (4) is removed from the exhaust manifold (3) to the anti-head side, or when the heat shield cover (4) is attached to the exhaust manifold (3) from the anti-head side, if the flat portion (4ag) of the upper heat shield plate (4a) is tilted downward toward the anti-head side and the heat shield cover (4) is slid sideways along this tilt, as shown in Figures 12(B) to (D), the lower heat shield plate (4b) does not interfere with the exhaust outlet flange (3b), but the flat portion (4ag) of the upper heat shield plate (4a) interferes with the tip portion (3ca) of the stud bolt (3c). Therefore, when attaching or detaching the heat insulating cover (4) to or from the exhaust manifold (3), it is necessary to remove the stud bolts (3c) from the exhaust outlet flange (3b). 12(E) to 12(H) are side views of FIGS. 12(A) to 12(D) viewed from the side opposite the head.

[0009] An object of the present invention is to provide an engine in which the heat shielding cover has high heat shielding properties and in which it is not necessary to remove the stud bolts from the exhaust flange when attaching or detaching the heat shield cover to or from the exhaust manifold. [Means for solving the problem]

[0010] The main features of the present invention are as follows. As illustrated in Figures 3 and 4, a portion of the exhaust manifold (3) sandwiched between the exhaust outlet flange (3b) and the cylinder head (2) is defined as a head-flange portion (3d), and as illustrated in Figures 3 to 5, the upper heat shield plate (4a) has an upper protruding portion (4aa) formed by protruding a part of the upper heat shield plate (4a) upward above the head-flange portion (3d), As illustrated in Figures 1(A) to 1(D), when the heat shield cover (4) is detached from the exhaust manifold (3) toward the opposite head side, or when the heat shield cover (4) is attached to the exhaust manifold (3) from the opposite head side, as illustrated in Figures 1(B) to 1(D), the heat shield cover (4) is slid laterally along the direction of the inclination with the upper end wall (4ad) of the upper protrusion (4aa) inclined downward toward the opposite head side, so that the tip end portion (3ca) of the stud bolt (3c) passes through the internal space (4ae) of the upper protrusion (4aa) as illustrated in Figures 1(C) and 1(D). [Effects of the Invention]

[0011] The present invention has the following advantages. Effect 1: The heat-shielding cover (4) has high heat-shielding properties. As illustrated in Figures 4 and 5, in this engine, the portion (3d) between the head flanges of the exhaust manifold (3) is not exposed above the upper heat shield plate (4a) due to the upward protrusion (4aa), and the heat shield cover (4) has high heat shielding properties.

[0012] <Effect 2> When attaching or detaching the heat insulating cover (4) to or from the exhaust manifold (3), it is not necessary to remove the stud bolts (3c) from the exhaust outlet flange (3b). As illustrated in Figure 1(A), in this engine, even if the upper and lower heat shield plates (4a) and (4b) are brought close to the portion between the head flanges (3d) in order to prevent the portion between the head flanges (3d) from being exposed from the anti-head side cover opening (4d), when attaching or detaching the heat shield cover (4) to or from the exhaust manifold (3) as illustrated in Figures 1(A) to 1(D), the tip portions (3ca) of the stud bolts (3c) pass through the internal space (4ae) of the upper protrusions (4aa) as illustrated in Figures 1(C) and 1(D), so there is no need to remove the stud bolts (3c) from the exhaust outlet flange (3b).

[0013] Effect 3: The heat-shielding cover (4) is highly rigid. As illustrated in Figures 3 to 5, in this engine, the upper raised portion (4aa), which is a part of the upper heat shield plate (4a) raised upward in a embossed shape, also functions as a reinforcing rib for the upper heat shield plate (4a), making the heat shield cover (4) less susceptible to thermal deformation. [Brief explanation of the drawings]

[0014] [Figure 1] 1(A) to 1(H) are side views of FIGS. 1(A) to 1(D) viewed from the opposite head side of FIGS. 1(A) to 1(D). In all of the drawings, the sheet metal heat shield cover (4) is transparent except for its outline so that the relationship between the internal space (4ae) of the upper protrusion (4aa) and the tip (3ca) of the stud bolt (3c) can be seen. [Figure 2] 2(A) is an explanatory diagram of a heat-shielding cover used in an engine according to an embodiment of the present invention, in which FIG. 2(A) is a side view seen from the opposite head side, FIG. 2(B) is a view taken in the direction of the arrow B in FIG. 2(A), FIG. 2(C) is a view taken in the direction of the arrow C in FIG. 2(A), FIG. 2(D) is a view taken in the direction of the arrow D in FIG. 2(A), FIG. 2(E) is a view taken in the direction of the arrow E in FIG. 2(A), and FIG. 2(F) is a view taken in the direction of the arrow F in FIG. 2(D). [Figure 3] 1 is a perspective view of an engine according to an embodiment of the present invention, viewed diagonally downward from the front side opposite the head, and is an exploded view with a heat insulating cover detached from an exhaust manifold. [Figure 4] In the perspective view of the engine with the heat shield cover attached to the exhaust manifold in Figure 3, the sheet metal heat shield cover is transparent except for the outline. [Figure 5] A perspective view of the engine corresponding to Figure 4, with the sheet metal heat shields left opaque. [Figure 6] 1 is a perspective view of an engine according to an embodiment of the present invention, viewed obliquely upward from the front side opposite the head side. FIG. [Figure 7] FIG. 1 is a plan view of an engine according to an embodiment of the present invention. [Figure 8] FIG. 8 is a side view of the exhaust side of the engine of FIG. [Figure 9] FIG. 8 is a front view of the engine of FIG. 7. [Figure 10] FIG. 8 is a side view of the intake side of the engine of FIG. 7. [Figure 11] FIG. 8 is a rear view of the engine of FIG. 7.

[0015] [Figure 12] These figures explain the procedure for removing and attaching a heat-shielding cover to an exhaust manifold in a prototype engine that precedes the present invention. Figure 12(A) is a front view of the heat-shielding cover when it is attached, Figure 12(B) is a front view of the heat-shielding cover just before it has started to be removed or just before it has been attached, Figure 12(C) is a front view of the heat-shielding cover when it is in the middle of being removed or attached, Figure 12(D) is a front view of the heat-shielding cover just before it has been removed or just after it has started to be attached, and Figures 12(E) to (H) are side views of Figures 12(A) to 12(D) seen from the opposite head side.In all of these figures, the sheet metal heat-shielding cover (4) is transparent except for the outline so that the relationship between the flat portion (4ag) of the upper heat-shielding plate (4a) and the tip portion (3ca) of the stud bolt (3c) can be seen. [Figure 13] 13(A) is an explanatory diagram of a heat-shielding cover used in a prototype engine prior to the present invention, where FIG. 13(A) is a side view from the opposite head side, FIG. 13(B) is a view viewed in the direction of arrow B of FIG. 13(A), FIG. 13(C) is a view viewed in the direction of arrow C of FIG. 13(A), FIG. 13(D) is a view viewed in the direction of arrow D of FIG. 13(A), FIG. 13(E) is a view viewed in the direction of arrow E of FIG. 13(A), and FIG. 13(F) is a view viewed in the direction of arrow F of FIG. 13(D). [Figure 14] FIG. 1 is a perspective view of a prototype engine prior to the present invention, viewed diagonally downward from the front side opposite the head, and is an exploded view with a heat insulating cover detached from the exhaust manifold. [Figure 15] In the perspective view of the engine shown in Figure 14 with the heat shield cover attached to the exhaust manifold, the sheet metal heat shield cover is transparent except for the outline. [Figure 16] A perspective view of the engine corresponding to Figure 15, with the sheet metal heat shields left opaque. [Figure 17]FIG. 1 is a perspective view of a prototype engine prior to the present invention, viewed obliquely upward from the front side opposite the head side. DETAILED DESCRIPTION OF THE INVENTION

[0016] 1 to 11 are diagrams illustrating an engine according to an embodiment of the present invention, and in this embodiment, a vertical, water-cooled, in-line multi-cylinder, four-cycle spark ignition engine will be described.

[0017] This engine is a dual-fuel engine, and as shown in Figure 5, includes a cylinder block (9), a cylinder head (2) attached to the top of the cylinder block (9), a cylinder head cover (17) attached to the top of the cylinder head (2), a gear case (18) attached to the front of the cylinder block (9), and an oil pan (19) attached to the bottom of the cylinder block (9). The cylinder block (9) includes a cylinder section (9b) in its upper half and a crankcase (9a) in its lower half. The crankcase (9a) houses the crankshaft (1). The engine includes an intake system, a fuel supply system, an ignition system, an engine cooling system, and an exhaust system.

[0018] The intake system is configured as follows. As shown in FIGS. 3 to 11, the direction in which the crankshaft (1) is installed is the front-rear direction, one side of the front-rear direction is the front, the other side is the rear, and the width direction of the engine perpendicular to the front-rear direction is the lateral direction. As shown in Figures 7 and 10, the intake system includes an intake manifold (20) disposed on one lateral side (right side) of the cylinder head (2) and an electronic throttle (21) attached to the front of the intake manifold (20). The throttle opening of the electronic throttle (21) is controlled by an electronic control device (22) shown in Figure 10. The electronic control unit 22 is an engine ECU 22a. EUC is an abbreviation for electronic control unit. As shown in Figure 10, the intake manifold (20) includes a rectangular parallelepiped intake collector (20a) that is long in the front-rear direction, and four intake branch pipes (20b) branching off from the intake collector (20a), and an electronic throttle (21) is attached to the front of the intake collector (20a). Although not shown, an intake valve that opens and closes a valve opening of an intake port in the cylinder head (2) is driven to open and close by a cam on a valve camshaft.

[0019] The fuel supply device is configured as follows. As shown in Figures 7 and 10, the fuel supply device includes a gas mixer (24) mounted in front of the electronic throttle (21), and as shown in Figures 9 and 11, a delivery pipe (25) installed in the intake side in the front-rear direction has a plurality of fuel injectors (26) attached in a branched manner at predetermined intervals in the front-rear direction to the delivery pipe (25). By switching the fuel injectors, it is possible to select between supplying gas fuel to the gas mixer (24) and supplying liquid fuel to the delivery pipe (25). The gas fuel supplied to the gas mixer (24) is mixed with air to form an air-fuel mixture, which is then supplied to each cylinder from the intake manifold (20). The liquid fuel supplied to the delivery pipe (25) is supplied to each cylinder from the fuel injector (26) through the intake port of each cylinder, where it forms an air-fuel mixture in each cylinder. The fuel gas may be LNG (liquefied natural gas), LPG (liquefied petroleum gas), or the like. The liquid fuel may be gasoline or the like.

[0020] The ignition device is configured as follows. As shown in Figures 7 and 11, the ignition device includes a plurality of coil-on plugs (27) corresponding to the respective cylinders, and the air-fuel mixture in each cylinder is ignited by a spark generated by the coil-on plugs (27). The amount of gas fuel supplied to the gas mixer (24), the timing of fuel injection from the fuel injector (26), the amount of fuel injection, and the ignition timing of the coil-on plug (27) are controlled by the engine ECU (22a) according to the engine rotation speed and the engine load. The injection timing from the fuel injector (26) and the ignition timing of the coil-on plug (27) are set based on the crank angle. The engine rotation speed and crank angle are calculated by the engine ECU (22a) based on the detection of the rotation state of the crankshaft (1) by the rotation detection sensor (10) shown in FIG. The rotation detection sensor (10) includes a sensor body (10a) inserted into the gear case (18) and a connector (10b) connected to the sensor body (10a), and a cable (8) extending from the connector (10b) is electrically connected to the engine ECU (22a).

[0021] The engine cooling system is configured as follows. As shown in Figures 7 and 8, the engine cooling device includes an engine cooling fan (7) disposed at the front of the engine, and the engine cooling fan (7) passes cooling air backward through a radiator (not shown) disposed in front of the engine, thereby dissipating heat from the engine cooling air passing through the radiator and air-cooling the engine by using the cooling air that has passed through the radiator as engine cooling air. The engine cooling fan (7) is driven by a crank pulley (1a) through a fan belt (12). The fan belt (12) is tensioned by a generator that also serves as a belt tensioner (13).

[0022] The exhaust system is configured as follows: As shown in Figures 7, 8 and 11, the exhaust system includes an exhaust manifold (3) arranged on the other lateral side (left side) of the cylinder head (2), opposite to the intake manifold (20) on one lateral side thereof, and a heat insulating cover (4) that covers the exhaust manifold (3). As shown in Figures 3 to 6, the side of the exhaust manifold (3) that is outwardly away from the exhaust side wall (2a) of the cylinder head (2) in the lateral direction is defined as the anti-head side, and the exhaust manifold (3) includes an exhaust collector portion (3a) and an exhaust outlet flange (3b) provided on the anti-head side of the exhaust collector portion (3a).

[0023] As shown in Figures 3 to 6, the heat shield cover (4) includes upper and lower heat shield plates (4a) and (4b) and a counter-head side heat shield plate (4c) that cover the exhaust manifold (3) from the upper, lower, and counter-head side, and the counter-head side has a counter-head side cover opening (4d) that exposes the end face (3ba) of the exhaust outlet flange (3b) on the counter-head side. As shown in FIGS. 4 to 6, a stud bolt 3c protrudes from an end face 3ba of the exhaust outlet flange 3b toward the opposite side to the head.

[0024] As shown in Figures 3 and 4, the portion of the exhaust manifold (3) sandwiched between the exhaust outlet flange (3b) and the cylinder head (2) is the head flange portion (3d), and as shown in Figures 3 to 5, the upper heat shield plate (4a) has an upper protrusion (4aa) formed by protruding a part of the upper heat shield plate (4a) upward above the head flange portion (3d).

[0025] As shown in Figures 1(A) to 1(D), when the heat shield cover (4) is detached from the exhaust manifold (3) toward the opposite side of the head, or when the heat shield cover (4) is attached to the exhaust manifold (3) from the opposite side of the head, as shown in Figures 1(B) to 1(D), the heat shield cover (4) is slid laterally along the direction of the inclination while the upper end wall (4ad) of the upper protrusion (4aa) is inclined downward toward the opposite side of the head, so that the tip end (3ca) of the stud bolt (3c) passes through the internal space (4ae) of the upper protrusion (4aa) as shown in Figures 1(C) and 1(D).

[0026] As shown in Figures 4 and 5, in this engine, the portion (3d) between the head flanges of the exhaust manifold (3) is not exposed above the upper heat shield plate (4a) due to the upper protrusion (4aa), and the heat shield cover (4) has high heat shielding properties.

[0027] As shown in Figure 1(A), in this engine, even if the upper and lower heat shield plates (4a) and (4b) are brought close to the portion between the head flanges (3d) in order to prevent the portion between the head flanges (3d) from being exposed from the anti-head side cover opening (4d), when attaching or detaching the heat shield cover (4) to or from the exhaust manifold (3) as shown in Figures 1(A) to 1(D), the tip portions (3ca) of the stud bolts (3c) pass through the internal space (4ae) of the upper protrusions (4aa) as shown in Figures 1(C) and 1(D), so it is not necessary to remove the stud bolts (3c) from the exhaust outlet flange (3b).

[0028] As shown in Figures 3 to 5, in this engine, the upper raised portion (4aa), which is a part of the upper heat shield plate (4a) raised upward in a embossed shape, also functions as a reinforcing rib for the upper heat shield plate (4a), making the heat shield cover (4) less susceptible to thermal deformation.

[0029] The procedure for removing the heat shield cover (4) from the exhaust manifold (3) is as follows. To remove the heat shield cover (4) shown in FIG. 1(A) from the exhaust manifold (3), the upper end wall (4ad) of the upper raised portion (4aa) in a horizontal position is tilted downward toward the opposite side of the head as shown in FIG. 1(B), and the heat shield cover (4) is slid laterally toward the opposite side of the head along the slope of the upper end wall (4ad) of the upper raised portion (4aa) as shown in FIG. 1(C) so that the tip portions (3ca) of the stud bolts (3c) pass through the internal spaces (4ae) of the upper raised portion (4aa). Once the tip portions (3ca) of the stud bolts (3c) have passed through the internal spaces (4ae) of the upper raised portion (4aa), as shown in FIG. 1(D), the heat shield cover (4) is removed from the exhaust manifold (3) toward the opposite side of the head.

[0030] The procedure for attaching the heat insulating cover (4) to the exhaust manifold (3) is as follows. To attach the heat shield cover (4) to the exhaust manifold (3), as shown in FIG. 1(D), the heat shield cover (4) is brought close to the exhaust manifold (3) from the side opposite the head, with the upper end wall (4ad) of the upper protrusion (4aa) inclined downward toward the side opposite the head, and the tip end (3ca) of the stud bolt (3c) is inserted from the head side into the internal space (4ae) of the upper protrusion (4aa). Then, as shown in FIG. 1(C), the heat shield cover (4) is attached to the exhaust manifold (3) along the direction of the inclination of the upper end wall (4ad) of the upper protrusion (4aa). By sliding the heat shield cover (4) laterally toward the head side, the tip (3ca) of the stud bolt (3c) passes through the internal space (4ae) of the upper raised portion (4aa), and as shown in FIG. 1(B), when the tip (3ca) of the stud bolt (3c) has passed through the internal space (4ae) of the upper raised portion (4aa), the inclined upper end wall (4ad) of the upper raised portion (4aa) is brought into a horizontal position as shown in FIG. 1(A), and the heat shield cover (4) is attached to the exhaust manifold (3).

[0031] As shown in FIG. 1(E), when viewed from the opposite side of the head, the end face (3ba) of the exhaust outlet flange (3b) is formed in a rectangular shape with both upper and lower edges (3bb) and (3bc) horizontal, and stud bolts (3c) protrude from each of the four corners of the end face (3ba). As shown in Figure 2(D), the upper protrusion (4aa) is formed in a horizontally elongated rectangular shape when viewed from above, and as shown in Figures 1(C), 1(D), 1(G), and 1(H), when the heat shield cover (4) is attached to or detached from the exhaust manifold (3), the tip portions (3ca) of a pair of front and rear stud bolts (3c) protruding from a pair of front and rear upper corner portions (3bc) protruding from the upper corners of the end face (3ba) of the exhaust outlet flange (3b) are configured to pass through the internal space (4ae) of the upper protrusion (4aa).

[0032] As shown in FIG. 1(E), in this engine, when viewed from the side opposite the head, the end face (3ba) of the exhaust outlet flange (3b) is square, and a stud bolt (3c) protrudes from each of the four corners of the end face (3ba). Therefore, when connecting a vertical or horizontal exhaust guideway (not shown) to the exhaust outlet flange (3b), the stud bolt (3c) is not hidden behind the piping of the exhaust guideway when viewed from the side opposite the head, making it easy to attach the exhaust guideway to the exhaust outlet flange (3b).

[0033] Furthermore, as shown in FIG. 1(E), in this engine, the end face (3ba) of the exhaust outlet flange (3b) is square, so the upper and lower height dimensions can be shorter than if it were circular. This allows the height dimension of the cover opening (4d) on the opposite side to the head, and therefore the distance between the upper and lower heat shield plates (4a) and (4b), to be shortened accordingly. In addition, the horizontal upper and lower end edges (3bb) and (3bc) are less likely to interfere with the upper end wall (4ad) of the upper protrusion (4aa) or the lower heat shield plate (4) when the heat shield cover (4) is attached to or detached from the exhaust manifold (3), so the heat shield cover (4) can be made compact.

[0034] 1(E)(H) and 2(A)(D)-(F), the upper heat shielding plate (4a) is provided with an upper additional raised portion (4af) on the rear side of the upper raised portion (4aa) by raising a part of the upper heat shielding plate (4a) upward in a embossed shape, and the upper additional raised portion (4af) is formed in a horizontally elongated rectangular shape when viewed from above. The upper additional raised portion (4af) may be disposed on the front side of the upper raised portion (4aa).

[0035] As shown in Figures 1(E)(H) and 2(A)(D) to (F), in this engine, the upper additional raised portion (4af), which is a part of the upper heat shield plate (4a) raised upward in a protruding shape, functions as a reinforcing rib for the upper heat shield plate (4a), so that the heat shield cover (4) has high rigidity and is less likely to undergo thermal deformation.

[0036] As shown in FIG. 2(D), the front-to-rear width of the upper additional protrusion (4af) is formed to be shorter than the front-to-rear width of the upper protrusion (4aa). In this engine, the upper additional protrusions (4af) function as reinforcing ribs, so the heat insulating cover (4) has high rigidity and is less likely to be thermally deformed.

[0037] As shown in Figures 3 to 5, the upper heat shield plate (4a) has an upper raised portion (4aa) and an upper additional raised portion (4af) as well as a flat portion (4ag), and the heat shield cover (4) is fixed to the exhaust manifold (3) with fasteners (5) that press the upper additional raised portion (4af) and the flat portion (4ag) from above.

[0038] As shown in Figures 3 to 5, in this engine, the flat portion (4ag) of the upper heat shield plate (4a), which is resistant to deformation due to pressure from above, and the upper additional raised portion (4af) with a short front-to-rear width receive pressure from above on the fastener (5), so the fastener (5) is less likely to loosen.

[0039] As shown in FIG. 3, the exhaust manifold (3) includes a plurality of exhaust branch pipes (3e) arranged in the front-to-rear direction to guide exhaust gas from a plurality of cylinders, and the portion of the exhaust collector portion (3a) adjacent to the anti-head side of each exhaust branch pipe (3e) is defined as an anti-head side collector portion (3ab), and as shown in FIGS. 3 to 5, each fastener (5) is fixed to each exhaust branch pipe (3e) or the anti-head side collector portion (3ab).

[0040] As shown in FIG. 3, in this engine, the heat shield cover (4) is pressed by the fasteners (5) at equal distances in the front-to-rear direction according to the arrangement of the exhaust branch pipes (3e) or the anti-head side collector portion (3ab), so that the pressure distribution on the heat shield cover (4) from the fasteners (5) is equalized, and distortion of the heat shield cover (4) due to the pressing force of the fasteners (5) is suppressed.

[0041] As shown in Figures 2(A) to (C) (E) (F) and Figure 6, the lower heat shielding plate (4b) has a lower raised portion (4ba) formed by raising a part of the lower heat shielding plate (4b) downward in a embossed shape, and the lower raised portion (4ba) is formed in a horizontally elongated rectangular shape when viewed from below.

[0042] As shown in Figures 2(A) to (C) (E) (F) and Figure 6, in this engine, the lower raised portion (4ba) formed by raising a part of the lower heat shield plate (4b) downward in a protruding shape functions as a reinforcing rib for the lower heat shield plate (4b), so that the heat shield cover (4) has high rigidity and is less likely to be thermally deformed.

[0043] As shown in Figures 1(A)(D) and 2(A)(B)(D) to (F), the upper protruding portion (4aa) has standing walls (4ab) that surround its internal space (4ae) from the front, rear, and anti-head sides, and a head-side opening (4ac) that opens the internal space (4ae) toward the cylinder head (2). In this engine, heat in the internal space (4ae) of the upper protrusion (4aa) escapes through the head-side opening (4ac) to the cylinder head (2), so that the upper protrusion (4aa) is unlikely to be thermally deformed.

[0044] As shown in Figures 3 to 5, this engine is a four-cylinder engine, and the portion between the head flanges (3d) includes a part of the exhaust collector portion (3a), a part of each exhaust branch pipe (3e) for the first and second cylinders, and the space between each exhaust branch pipe (3e) for the first and second cylinders. The portion between the head flanges (3d) may be located between the exhaust branch pipes (3e) of the second and third cylinders, or between the exhaust branch pipes (3e) of the second and third cylinders. In this engine, the front cylinder is cylinder 1 and the rear cylinder is cylinder 4.

[0045] As shown in Figures 1(A) and 2(A)(B), the upper opening edge (4da) of the anti-head side cover opening (4d) is positioned at the same height as the flat portion (4ag) of the upper heat shield plate (4a), and the lower opening edge (4db) of the anti-head side cover opening (4d) is positioned at the same height as the flat portion (4bb) of the lower heat shield plate (4b).

[0046] As shown in Figure 1(E), when viewed from the opposite head side, the exhaust outlet flange (3b) is formed in a rectangular shape that is slightly longer in the front-to-rear direction, and its upper edge (3bb) is at the same height as the upper end of the exhaust collector portion (3a), and its lower edge (3bc) is positioned at a height lower than the flat portion (4bb) of the lower heat shield plate (4b). Of the four corners of the end face (3ba) of the exhaust outlet flange (3b), a pair of upper protrusions, one in front and one out back, on the upper side are provided with upwardly convex semicircular arc-shaped upper projections, and a pair of lower protrusions, one in front and one out back, on the lower side are provided with downwardly convex semicircular arc-shaped lower projections, and stud bolts (3c) are threadedly fitted into the female threaded holes provided in these upper and lower protrusions.

[0047] As shown in FIGS. 7 and 8, the heat shield cover (4) includes front and rear heat shield plates (4e) and (4f) that cover the exhaust manifold (3) from the front and rear sides. As shown in FIG. 7, the front heat shield (4e) is formed in an inclined shape that moves away from the cylinder head (2) toward the opposite side of the head as it approaches the rear, and the engine cooling air that passes between the belt tensioner (13) and the cylinder head (2) is guided by the inclination of the front heat shield (4e) to an exhaust outlet passage (not shown) connected to the exhaust outlet flange (3b). As shown in FIG. 7, the rear heat shield plate (4f) is formed in an inclined shape that approaches the cylinder head (2) as it approaches the rear, and a rear opening (4fa) is formed at the rearmost end, and heat inside the heat shield cover (4) is released rearward from the rear opening (4fa).

[0048] As shown in FIG. 9, the engine cooling fan (7) is an axial flow type and can be arranged in two different positions: an upper position and a lower position. In the case of the upper arrangement, the crankshaft sensor (10) is arranged so that a part of the connector (10b) overlaps with the projected area of ​​the engine cooling fan (7) located inside the upper fan rotation trajectory (7a) when viewed from the front side. In the case of the lower positioning, the crankshaft sensor (10) is positioned so that the exposed portion of the sensor body (10a) and the entire connector (10b) overlap with the projected area of ​​the engine cooling fan (7) located inside the lower fan rotation trajectory (7b) when viewed from the front side. In this engine, the crankshaft sensor (10) is cooled by the engine cooling air flowing backward, and the crankshaft sensor (10) is prevented from overheating due to heat generated by the engine, so that the rotational state of the crankshaft (1) is detected with high accuracy.

[0049] As shown in FIG. 9, when viewed from the front side of the engine, the cable (8) led out from the connector (10b) is introduced into a head exhaust side gap (2b) between the belt tensioner (13) of the fan belt (12) of the engine cooling fan (7) and the exhaust side wall (2a) of the cylinder head (2), and is led out from this head exhaust side gap (2b) to the intake side of the engine via the front side of the heat insulating cover (4) shown in FIG. 8 and the upper side of the engine shown in FIG. 7. In this engine, the cable (8) does not come into contact with the heat shield cover (4) or the exhaust guide pipe (not shown) connected to the exhaust outlet flange (3b) of the exhaust manifold (3), and the cable (8) is less likely to be damaged by heat. [Explanation of symbols]

[0050] (1)...crankshaft, (2)...cylinder head, (3)...exhaust manifold, (3a)...exhaust collector portion, (3ab)...opposite-head-side collector portion, (3b)...exhaust outlet flange, (3ba)...end face, (3bb)...upper edge, (3bc)...lower edge, (3c)...stud bolt, (3ca)...tip portion, (3d)...portion between head flanges, (3e)...exhaust branch pipe, (4)...heat shield cover, (4a)...upper heat shield plate, (4aa)...upper raised portion, (4ab)...standing wall, (4ac)...head-side opening, (4ad)...upper end wall, (4ae)...internal space, (4af)...upper additional raised portion, (4b)...lower heat shield plate, (4ba)...lower raised portion, (4c)...opposite-head-side heat shield plate, (4d)...opposite-head-side cover opening, (5)...fastener.

Claims

1. The crankshaft (1) is installed in a longitudinal direction, and the width direction of the engine, which is perpendicular to the longitudinal direction, is the horizontal direction. The engine is provided with an exhaust manifold (3) arranged on one side of the cylinder head (2) in the horizontal direction, and a heat insulating cover (4) that covers the exhaust manifold (3). The exhaust manifold (3) includes an exhaust collector portion (3a) and an exhaust outlet flange (3b) provided on the opposite side of the exhaust collector portion (3a), with the side facing outward from the exhaust side wall (2a) of the cylinder head (2) being the opposite side of the head in the lateral direction. The heat shield cover (4) includes upper and lower heat shield plates (4a) and (4b) and a counter-head-side heat shield plate (4c) that cover the upper, lower, and counter-head-side sides of the exhaust manifold (3). The counter-head-side heat shield plate (4c) is provided with a counter-head-side cover opening (4d) that exposes the end face (3ba) of the exhaust outlet flange (3b) to the counter-head side. A stud bolt (3c) protrudes from the end face (3ba) of the exhaust outlet flange (3b) to the counter-head side. The portion of the exhaust manifold (3) sandwiched between the exhaust outlet flange (3b) and the cylinder head (2) is defined as a head flange portion (3d), and the upper heat shield plate (4a) is provided with an upper raised portion (4aa) formed by raising a part of the upper heat shield plate (4a) upward in a embossed shape above the head flange portion (3d). This engine is characterized in that, when the heat shield cover (4) is detached from the exhaust manifold (3) toward the opposite head side, or when the heat shield cover (4) is attached to the exhaust manifold (3) from the opposite head side, the upper end wall (4ad) of the upper raised portion (4aa) is tilted downward toward the opposite head side, and the heat shield cover (4) is slid laterally along the direction of this tilt, so that the tip portion (3ca) of the stud bolt (3c) passes through the internal space (4ae) of the upper raised portion (4aa).

2. 2. The engine according to claim 1, When viewed from the opposite side of the head, the end face (3ba) of the exhaust outlet flange (3b) is formed in a rectangular shape with both upper and lower edges (3bb) and (3bc) horizontal, and stud bolts (3c) protrude from each of the four corners of the end face (3ba). When viewed from above, the upper raised portion (4aa) is formed in a horizontally elongated rectangular shape, and is configured so that, when the heat shield cover (4) is attached to or detached from the exhaust manifold (3), the tip portions (3ca) of a pair of front and rear stud bolts (3c) protruding from the upper corners of the end face (3ba) of the exhaust outlet flange (3b) pass through an internal space (4ae) of the upper raised portion (4aa).

3. 3. The engine according to claim 2, The engine is characterized in that the upper heat shield (4a) is provided with an upper additional raised portion (4af) on the rear or front side of the upper raised portion (4aa) by raising a part of the upper heat shield (4a) upward in a embossed shape, and the upper additional raised portion (4af) is formed in a horizontally elongated rectangular shape when viewed from above.

4. 4. The engine according to claim 3, An engine characterized in that the front-to-rear width of the upper additional raised portion (4af) is formed shorter than the front-to-rear width of the upper raised portion (4aa).

5. 5. The engine according to claim 4, The engine is characterized in that the upper heat shield plate (4a) has an upper raised portion (4aa) and an upper additional raised portion (4af) as well as a flat portion (4ag), and the heat shield cover (4) is fixed to the exhaust manifold (3) with fasteners (5) that press the upper additional raised portion (4af) and the flat portion (4ag) from above.

6. 6. The engine according to claim 5, The engine is characterized in that the exhaust manifold (3) is provided with a plurality of exhaust branch pipes (3e) arranged in a longitudinal direction for guiding exhaust gas from a plurality of cylinders, and the portions of the exhaust collector section (3a) adjacent to the opposite side of the head of each exhaust branch pipe (3e) are defined as opposite-head-side collector sections (3ab), and each fastener (5) is fixed to either each exhaust branch pipe (3e) or the opposite-head-side collector section (3ab) of each exhaust branch pipe (3e).

7. In the engine according to any one of claims 1 to 6, The engine is characterized in that the lower heat shield (4b) has a lower raised portion (4ba) formed by raising a part of the lower heat shield (4b) downward in a embossed shape, and the lower raised portion (4ba) is formed in a horizontally elongated rectangular shape when viewed from below.

8. In the engine according to any one of claims 1 to 6, The upper raised portion (4aa) is provided with a standing wall (4ab) that surrounds the internal space (4ae) from the front, rear, and opposite head sides, and a head-side opening (4ac) that opens the internal space (4ae) to the cylinder head (2).

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