JP2022171106A - dual fuel engine - Google Patents

Abstract

To provide a dual fuel engine capable of suppressing a temperature rise of liquid fuel 34a stagnating in a delivery pipe 5 during gas fuel operation.SOLUTION: A dual fuel engine includes an intake manifold 3, a cylinder head cover 28, and an axial flow type engine cooling fan 7. As viewed in a direction parallel to the central axis 8a of a crankshaft 8, between the intake manifold 3 and the cylinder head cover 28, the entirety of the delivery pipe 5 is located at a position overlapping with blades 7a of an engine cooling fan 7. The periphery of the delivery pipe 5 is used as an air blast path 9. A gas mixer 6 is attached to the end of a collector portion 3a of the intake manifold 3, and the gas mixer 6 faces the air blast inlet 9a of the air blast path 9 from its peripheral side.SELECTED DRAWING: Figure 1

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dual fuel engine, and more particularly to a dual fuel engine capable of suppressing temperature rise of liquid fuel stagnant in a delivery pipe during gas fuel operation.

Conventionally, a plurality of fuel injectors, a delivery pipe for distributing liquid fuel to the plurality of fuel injectors, and a gas mixer are provided, and liquid fuel operation and gas fuel operation can be switched between each other. There is a dual fuel engine in which liquid fuel is injected from the engine to form an air-fuel mixture, and air and gas fuel are mixed in a gas mixer to form an air-fuel mixture during gas fuel operation (see, for example, Patent Document 1).
This type of engine has the advantage that the user can select and operate a fuel that is easy to handle, and if a clean image is required, a gas fuel such as LPG, which has a clean image, can be selected and used.

Japanese Unexamined Patent Application Publication No. 2017-14961 (see FIGS. 1 and 4)

<Problem> During gas fuel operation, the liquid fuel stagnating in the delivery pipe may rise in temperature.
In the engine of Patent Document 1, when viewed in a direction parallel to the central axis of the crankshaft, part of the liquid fuel delivery pipe is arranged at a position that does not overlap with the engine cooling fan. There is a risk that the temperature of the liquid fuel stagnating in the delivery pipe will rise during gas fuel operation due to the small amount of wind. A rise in the temperature of the liquid fuel causes percolation, so it must be avoided.

SUMMARY OF THE INVENTION An object of the present invention is to provide a dual fuel engine in which temperature rise of liquid fuel stagnating in a delivery pipe is suppressed during gas fuel operation.

The main configuration of the present invention is as follows.
As illustrated in FIG. 1, it comprises an intake manifold (3), a cylinder head cover (28) and an axial engine cooling fan (7) oriented parallel to the central axis (8a) of the crankshaft (8). As can be seen, between the intake manifold (3) and the cylinder head cover (28), the entirety of the delivery pipe (5) is positioned so as to overlap the blades (7a) of the engine cooling fan (7), and the delivery pipe (5) A gas mixer (6) is attached to the end of the collector (3a) of the intake manifold (3). ) from its peripheral side.

The present invention has the following effects.
<<Effect 1>> It is possible to suppress the temperature rise of the liquid fuel (34a) stagnating in the delivery pipe (5) during gas fuel operation.
As illustrated in FIG. 1, in this engine, the engine cooling air (7f) generated by the engine cooling fan (7) flows into the air passage (9) around the delivery pipe (5) overlapping the blades (7a). It is possible to suppress the temperature rise of the liquid fuel (34a) supplied in large quantity and stagnating in the delivery pipe (5) during gas fuel operation.

As illustrated in FIG. 1, the engine cooling air (7f) supplied to the air inlet (9a) of the air passage (9) is prevented from diffusing in the peripheral direction of the air inlet (9a) by the gas mixer (6). Therefore, the air volume of the engine cooling air (7f) for cooling the delivery pipe (5) is relatively large.
As shown in FIG. 1, the gas mixer (6) receives radiant heat from the cylinder head (1) while the engine is running. ), and its surface temperature is maintained at a relatively low temperature, the engine cooling air (7f) guided by the surface of the gas mixer (6) is supplied to the air passage (9) without increasing in temperature. be.
In addition, since the delivery pipe (5) is located between the intake manifold (3) and the cylinder head cover (28), which have relatively low surface temperatures, the temperature rise of the liquid fuel (34a) due to radiant heat from these is also small. .

<<Effect 2>> The gas mixer (6) can also be used as a diffusion preventing component for the engine cooling air (7f).
As shown in FIG. 1, in this engine, the gas mixer (6) suppresses the diffusion of the blower inlet (9a) in the peripheral direction, so the gas mixer (6) is used as a diffusion prevention component for the engine cooling air (7f). can also be used as

FIG. 6 is a diagram for explaining the cooling structure of the delivery pipe of the engine according to the embodiment of the present invention, and is a front view in which a water pump and an engine cooling fan are overlapped with a sectional view taken along the line II of FIG. 5 . FIG. 6 is a sectional view taken along line II-II of FIG. 5; 8 is a cross-sectional view taken along line III-III of FIG. 7; FIG. 1 is a front view of an engine according to an embodiment of the invention; FIG. Figure 5 is a side view of the intake side of the engine of Figure 4; 5 is a side view of the exhaust side of the engine of FIG. 4; FIG. Figure 5 is a plan view of the engine of Figure 4; Figure 5 is a rear view of the engine of Figure 4;

1 to 8 are diagrams for explaining an engine according to an embodiment of the present invention. In this embodiment, a vertical water-cooled series multi-cylinder dual fuel engine will be explained.

As shown in FIGS. 4 to 8, this engine includes a cylinder block (27), a cylinder head (1) assembled on the upper part of the cylinder block (27), and a cylinder head (1) assembled on the upper part of the cylinder head (1). A head cover (28), a front case (29) assembled to the front side of the cylinder block (27) with the direction of the central axis (8a) of the crankshaft (8) as the front-rear direction, and a front case (29) mounted to the rear of the cylinder block (27). It has a flywheel housing (30) arranged and an oil pan (31) assembled under the cylinder block (27). As shown in FIG. 8, a flywheel (30a) is accommodated in the flywheel housing (30).
This engine includes an intake system, a fuel supply system, an ignition system, an exhaust system, a breather system, a water cooling system, and a lubrication system.

As shown in FIG. 4, the intake system of this engine consists of an intake manifold (3) mounted on one lateral side of the cylinder head (1) with the width direction of the engine as the lateral direction, and an intake manifold (3) shown in FIG. 3) is connected to the throttle body (32) attached to the front end of the collector portion (3a), the gas mixer (6) attached to the front portion of the throttle body (32), and the gas mixer (6) shown in FIG. An air cleaner (33) is provided, and air (33a) from the air cleaner (33) is supplied to the intake manifold (3) through the gas mixer (6) and the throttle body (32) in order.
As shown in FIG. 2, the intake manifold (3) has a rectangular box-shaped collector portion (3a) installed parallel to the central axis (8a) of the crankshaft (8), and a collector portion (3a). A plurality of branch portions (3b) are provided downwardly led out from the lateral side, and each branch portion (3b) communicates with the intake port (1a) of the cylinder head (1) and from the air cleaner (33) shown in FIG. Air (33a) introduced into collector portion (3a) shown in FIG. 2 through gas mixer (6) and throttle body (32) in order is distributed to each intake port (1a) through each branch portion (3b). be done.
As shown in FIG. 2, each of the branch portions (3b) is L-shaped when viewed in a direction parallel to the central axis (8a) of the crankshaft (8).
This engine is a four-cylinder engine, and has four branch portions (3b) and four intake ports (1a). Four branches (3b) are shown in FIGS.

As shown in FIG. 7, the fuel supply system for this engine includes a liquid fuel tank (34), a liquid fuel supply pump (35), a delivery pipe (5), and a plurality of fuel tanks attached to the delivery pipe (5). A fuel injector (4) is provided, each fuel injector (4) is inserted into the cylinder head (1), and liquid fuel (34a) in a liquid fuel tank (34) is supplied to a delivery pipe (5) by a liquid fuel supply pump (35). , and as shown in FIG. 2, liquid fuel (34a) is injected from each fuel injector (4) into air (33a) passing through each intake port (1a).
As shown in FIGS. 5 and 7, four fuel injectors (4) are arranged.
Gasoline is used as the liquid fuel (34a).

As shown in FIG. 1, the fuel supply system for this engine comprises a liquefied gas fuel source (36), a vaporizer (37), a gas regulator (10) and a gas mixer (6). ) is vaporized by the vaporizer (37) to become the gas fuel (37a), the pressure of the gas fuel (37a) is adjusted by the gas regulator (10), supplied to the gas mixer (6), and the gas mixer ( At 6), the mixture is mixed with air (33a) from the air cleaner (33) to form an air-fuel mixture, and the air-fuel mixture is introduced from the throttle body (32) shown in FIG. , to each intake port (1a) shown in FIG. 2 via each branch portion (3b).
A liquefied gas fuel cylinder is used as the liquefied gas fuel source (36) shown in FIG. Liquefied petroleum gas, liquefied natural gas, and other liquefied gas fuels can be used as the liquefied gas fuel (36a).

As shown in FIG. 1, the engine fuel supply system includes a fuel switching operation device (38) and an electronic control device (39). Control of device 39 alternates between liquid fuel operation and gas fuel operation.
The fuel switching operation device (38) is a fuel switching operation lever (38a), and the electronic control unit (39) is an engine ECU (39a). ECU is an abbreviation for electronic control unit.
The electronic control device (39) is electrically connected to the gas regulator (10) and the fuel injector (4). (not shown) is closed, and the solenoid valve (not shown) of the fuel injector (4) is opened at a predetermined timing for a predetermined time, thereby injecting a predetermined amount of liquid fuel (34a) at a predetermined timing. When liquid fuel operation is performed and the fuel switching operation device (38) is switched to the gas fuel side, the electromagnetic valve of the fuel injector (4) is normally closed and the metering valve of the gas regulator (10) is opened. As a result, the gas fuel (37a) is supplied from the gas regulator (10) to the gas mixer (6), and gas fuel operation is performed.

As shown in FIG. 2, the ignition system of this engine comprises an electronic controller (39), an ignition coil (40), a spark plug (not shown), and a plug cap (13) for the spark plug. Under the control of the control device (39), high voltage generated by the ignition coil (40) causes a spark to fly from between the electrodes of each spark plug, igniting the mixture of liquid fuel or gas fuel in each cylinder (2). .
Each ignition coil (40) is integrally attached to each plug cap (13). Each plug cap (13) is connected to each spark plug. A spark plug is mounted on the cylinder head (1), and electrodes for emitting sparks face the inside of each cylinder (2).

The exhaust system of this engine has an exhaust manifold (20a) shown in FIG. 6 assembled on the opposite horizontal side of the cylinder head (1) shown in FIG. I have.

As shown in FIG. 7, the breather device of this engine has a PCV system (11). PCV is an abbreviation for positive crankcase ventilation.
The PCV system (11) consists of a breather chamber (42) arranged in the cylinder head cover (28), a PCV valve (43) arranged at the outlet of the breather chamber, and a blow-by gas outlet tube led out from the PCV valve (43). (44), blow-by gas introduction port (3c) of intake manifold (3) connected to outlet end of blow-by gas outlet tube (44), air cleaner (33) and gas mixer (6) shown in FIGS. A fresh air lead-out tube (45) led out from between and a fresh air lead-in case (12) connected to the lead-out end of the fresh air lead-out tube (45), the fresh air lead-in case (12) being the front case ( 29) communicates with the crank chamber (2c) shown in FIG.

In the PCV system (11), during normal operation, the blow-by gas (42a) flowing out from each cylinder (2) shown in FIG. 2 into the crank chamber (2c) flows from the breather chamber (42) shown in FIG. (43) into the intake manifold (3), the inside of the crank chamber (2c) shown in FIG. The case (29) is ventilated with fresh air (33b) introduced sequentially through the case (29).

As shown in FIG. 1, the water cooling system for this engine includes a water pump (15), a cylinder cooling water jacket (2b), a head cooling water jacket (1b), a head cooling water outlet case (14), and a radiator. (16), a radiator inlet hose (18), a radiator outlet hose (19), and a bypass tube (14b).
The head cooling water lead-out case (14) has a thermostat chamber (14a), a thermostat valve (14d) housed in the thermostat chamber (14a), a radiator side outlet (14e), and a bypass side outlet (14f). there is The water pump (15) also has a bypass inlet case (15a).

As shown in FIG. 1, the radiator side outlet (14e) of the head cooling water lead-out case (14) communicates with the hot water inlet of the radiator (16) through a radiator inlet side hose (18). The facility water outlet of is communicated with the facility water inlet (15c) of the water pump (15) through the radiator outlet side hose (19).
A bypass side outlet (14f) of the head cooling water outlet case (14) communicates with a bypass inlet case (15a) of the water pump (15) through a bypass tube (14b).

When the temperature of the engine cooling water (1c) flowing into the thermostat chamber (14a) from the head cooling water jacket (1b) shown in FIG. The engine cooling water (1c) pumped by the water pump (15) flows through the cylinder cooling water jacket (2b), the head cooling water jacket (1b), and the thermostat chamber (14a) of the head cooling water lead-out case (14). After that, as indicated by the arrow of the engine cooling water (14c), it flows back from the bypass inlet case (15a) to the water pump (15) through the bypass side outlet (14f) and the bypass tube (14b) in order, and flows into the radiator (14c). By bypassing 16), the water temperature is raised quickly.

When the temperature of the engine cooling water (1c) flowing into the thermostat chamber (14a) from the head cooling water jacket (1b) shown in FIG. 1 becomes relatively high (80°C or higher), the thermostat valve (14d) is fully opened Then, the engine cooling water (1c) pumped by the cooling water pump (15) is sent to the cylinder cooling water jacket (2b), the head cooling water jacket (1b), and the thermostat chamber ( 14a) through the radiator side outlet (14e), the radiator inlet side hose (18), the radiator (16), and the radiator outlet side hose (19) in order like the arrow of the engine cooling water (1c). The water is then returned to the water pump (15) and cooled by the heat released by the radiator (16).

The radiator (16) shown in FIG. 1 is air-cooled by engine cooling air generated by an engine cooling fan (7).
As shown in FIG. 4, fan pulley (7e) of engine cooling fan (7) is driven from crank pulley (8b) via fan belt (8c), and fan belt (8c) is driven by belt tensioner (22). Tension is adjusted.
The belt tensioner (22) swings at its upper end about a fulcrum (22a) at its lower end, and its upper end is fixed to a stay (22b) at a predetermined swinging position.
The tension pulley (22c) of the belt tensioner (22) is laterally covered with a belt cover (22d).

As shown in FIG. 4, the lubrication system for this engine consists of an oil pump (46) arranged in the front case (29) and an oil filter (47) mounted on the lateral side of the front case (29). and an oil cooler (48) and an oil gallery (not shown) formed in the cylinder block (27). Then, the oil passes through an oil filter (47) and an oil cooler (48), and is supplied from the oil gallery to sliding parts such as bearings (not shown) of the crankshaft (8).

As shown in FIG. 1, the engine comprises a plurality of fuel injectors (4), a delivery pipe (5) for distributing liquid fuel (34a) to the plurality of fuel injectors (4), a gas mixer (6), Liquid fuel operation and gas fuel operation can be switched between each other, and during liquid fuel operation, liquid fuel (34a) is injected from fuel injector (4) into air (33a) shown in FIG. 2 to form a mixture, During gas fuel operation, air (33a) and gas fuel (37a) are mixed in the gas mixer (6) shown in FIG. 1 to form an air-fuel mixture.
This type of engine has the advantage that the user can select and operate a fuel that is easy to handle, and if a clean image is desired, a gas fuel such as LPG with a clean image can be selected and used.

As shown in FIG. 1, this engine is equipped with an axial engine cooling fan (7), and when viewed in a direction parallel to the central axis (8a) of the crankshaft (8), the entire delivery pipe (5) is arranged at a position overlapping the blades (7a) of the engine cooling fan (7), the circumference of the delivery pipe (5) is used as an air passage (9), and at the end of the collector (3a) of the intake manifold (3) A gas mixer (6) is attached, and this gas mixer (6) faces the air inlet (9a) of the air passage (9) from its peripheral side (upper side).

As shown in FIG. 1, in this engine, a large amount of engine cooling air (7f) generated by the engine cooling fan (7) passes through the air passage (9) around the delivery pipe (5) overlapping the blades (7a). It is possible to suppress the temperature rise of the liquid fuel (34a) supplied to and stagnant in the delivery pipe (5) during gas fuel operation.

As shown in FIG. 1, the engine cooling air (7f) supplied to the air inlet (9a) of the air passage (9) is blown by the gas mixer (6) in the peripheral direction (upward) of the air inlet (9a). Since the diffusion is suppressed, the air volume of the engine cooling air (7f) for cooling the delivery pipe (5) is relatively large.
As shown in FIG. 1, during engine operation, the gas mixer (6) receives radiant heat from the cylinder head (1), and during gas fuel operation, air (33a) and gas fuel (37a) passing through the inside are and its surface temperature is maintained at a relatively low temperature, the engine cooling air (7f) guided by the surface of the gas mixer (6) is supplied to the air passage (9) without increasing its temperature. .
Also, since the delivery pipe (5) is located between the intake manifold (3) and the cylinder head cover (28), which have relatively low surface temperatures, the temperature rise of the liquid fuel (34a) due to radiant heat from these is small. or almost none.

As shown in FIG. 1, in this engine, the gas mixer (6) suppresses diffusion of the engine cooling air (7f) in the peripheral direction (upward direction) of the air inlet (9a). It can also be used as a diffusion prevention component for the engine cooling air (7f).

As shown in FIG. 2, in this engine, the peripheral wall (5a) of the delivery pipe (5) is made of sheet metal.
In this engine, the delivery pipe (5) can be made slimmer than that made of cast iron, the heat capacity can be reduced, the surrounding air passage (9) can be widened, and the liquid stagnating in the delivery pipe (5) can be removed. The efficiency of cooling the fuel (34a) is increased.

As shown in FIG. 2, in this engine, the peripheral wall (5a) of the delivery pipe (5) is a rectangular cylinder, and the fuel injector (4) is attached to one side portion (one diagonally lower side portion), and the remaining three side portions. faces the air duct (9).
In this engine, the heat dissipation area of the peripheral wall (5a) of the delivery pipe (5) is large, and the cooling efficiency of the liquid fuel (34a) stagnating in the delivery pipe (5) is enhanced.

As shown in FIG. 1, in this engine, when viewed in a direction parallel to the central axis (8a) of the crankshaft (8), the delivery pipe (5) is located on the tip side of the blades (7a) of the engine cooling fan (7). It is positioned so that it overlaps the half.
In this engine, a large amount of engine cooling air generated at the tip side half of the blades (7a), which rotate at high speed, is supplied to the air duct (9) around the delivery pipe (5), and in the delivery pipe (5) The efficiency of cooling the stagnant liquid fuel (34a) is enhanced.

As shown in FIG. 1, in this engine, a gas regulator (10) is connected to a gas mixer (6). coming from

In this engine, engine cooling air supplied to the air inlet (9a) of the air passage (9) is prevented from diffusing in the peripheral direction (upward direction) of the air inlet (9a) by the gas regulator (10). Therefore, the air volume of the engine cooling air (7f) for cooling the delivery pipe (5) is relatively large.
The gas regulator (10), which receives radiant heat from the cylinder head (1) during engine operation, is cooled by the gas fuel (37a) passing through the interior during gas fuel operation, and its surface temperature is relatively low. The engine cooling air, which is maintained at a low temperature and whose diffusion is suppressed on the surface of the gas regulator (10), is supplied to the air passage (9) without increasing its temperature.

In this engine, the gas regulator (10) suppresses diffusion of the engine cooling air (7f) in the peripheral direction (upward direction) of the air inlet (9a). It can also be used as the diffusion prevention component of (7f).

As shown in FIG. 1, this engine is equipped with a fresh air introduction case (12) of a PCV system (11), and this fresh air introduction case (12) is positioned at a blast inlet (9a) of a blast passage (9). It is facing from the side (bottom side).

In this engine, the engine cooling air (7f) supplied to the air inlet (9a) of the air passage (9) is diffused in the peripheral direction (downward) of the air inlet (9a) by the fresh air introduction case (12). is suppressed, the air volume of the engine cooling air (7f) for cooling the delivery pipe (5) becomes relatively large.
The surface of the fresh air introduction case (12) receiving radiant heat from the cylinder head (1) during engine operation is cooled by the fresh air (33b) passing through the inside during engine operation, and the surface temperature is The engine cooling air (7f), which is maintained at a relatively low temperature and whose diffusion is suppressed on the surface of the fresh air introduction case (12), is supplied to the air passage (9) without increasing its temperature.

In this engine, the fresh air introduction case (12) suppresses diffusion of the engine cooling air (7f) in the peripheral direction (downward) of the air inlet (9a), so the fresh air introduction case (12) is used. It can also be used as a diffusion prevention component for the engine cooling air (7f).

As shown in FIGS. 1 and 2, this engine has a plug cap (13) of an ignition plug, and the outer peripheral surface of the plug cap (13) of the ignition plug faces the air passage (9).
In this engine, the plug cap (13) of the spark plug is cooled by the engine cooling air (7f) passing through the air passage (9), thereby suppressing thermal damage and thermal deterioration of the spark plug and plug cap (13).

As shown in FIG. 1, this engine has a head cooling water outlet case (14) attached to the cylinder head (1), and when viewed parallel to the central axis (8a) of the crankshaft (8), Assuming a fan center imaginary line (7c) that is parallel to the cylinder center axis (2a) and passes through the rotation center (7b) of the engine cooling fan (7), and with the fan center imaginary line (7c) as a boundary, the delivery pipe Assuming an exhaust-side blowing area (7d) located on the opposite side of the air intake (9a) of the intake-side blowing passage (9) around (5), in the exhaust-side blowing area (7d) A head cooling water lead-out case (14) is arranged.

In this engine, the heat of the head cooling water lead-out case (14) is absorbed by the engine cooling air (7g) passing through the air blowing area (7d) on the exhaust side, making it difficult for it to flow into the air blowing passage (9) on the intake side. Therefore, the cooling efficiency of the liquid fuel (34a) stagnating in the delivery pipe (5) is enhanced.
During engine operation, high-temperature engine cooling water (1c) immediately after flowing out from the cylinder head (1) passes through the head cooling water outlet case (14), so the surface of the head cooling water outlet case (14) Although the temperature becomes relatively high, the heat is difficult to flow into the intake air passage (9).

As shown in FIG. 1, this engine includes a thermostat chamber (14a) provided in a head cooling water lead-out case (14), a bypass tube (14b) led out from the thermostat chamber (14a), and a bypass tube (14b). ), the engine cooling water (14c) in the thermostat chamber (14a) bypasses the radiator (16) and enters the bypass inlet case (15a) of the water pump (15). It is configured to be sucked into (15a).
As shown in FIG. 1, in this engine, the engine cooling fan (7) has a central blade mounting base (7h) and blades (7a) projecting radially from the peripheral edge of the blade mounting base (7h), When viewed parallel to the crankshaft 8, the bypass inlet case 15a of the water pump 15 is positioned so as to overlap the blade mounting base plate 7h of the engine cooling fan 7.

In this engine, the heat of the bypass inlet case (15a) of the water pump (15) is difficult to flow into the intake side air passage (9), so the liquid fuel (34a) stagnant in the delivery pipe (5) Increases cooling efficiency.
During engine operation, the high-temperature engine cooling water (14c) immediately after flowing out of the head cooling water discharge case (14) passes through the bypass inlet case (15a) of the water pump (15). ) becomes relatively high, but the heat of the bypass inlet case (15a), which overlaps the blade mounting board (7h) of the engine cooling fan (7), is difficult to transfer to the engine cooling air (7f), and the intake side It is difficult for the air to flow into the air duct (9).

As shown in FIG. 1, a radiating water inlet pipe (15b) attached to a bypass inlet case (15a) of a water pump (15) and a head cooling water jacket (1b) of a cylinder head (1) are provided. The engine cooling water (1c) from the water jacket (1b) passes through the radiator (17a) of the air conditioner (17) and enters the bypass inlet case (15a) of the water pump (15) from the facility water inlet pipe (15b). configured to be aspirated.
As shown in FIG. 1, when viewed parallel to the central axis (8a) of the crankshaft (8), the facility water inlet is closer to the delivery pipe (5) than the thermostat chamber (14a) and the bypass inlet case (15a). A pipe (15b) is arranged.

In this engine, radiant heat from the relatively high-temperature thermostat chamber (14a) and the bypass inlet case (15a) is blocked by the relatively low-temperature facility water inlet pipe (15b) during engine operation, and is close to the delivery pipe (5). Since the engine cooling air (7f) passing through the blower inlet (9a) is not heated, the cooling efficiency of the liquid fuel (34a) stagnant in the delivery pipe (5) is enhanced.
During the heat dissipation of the air conditioner (17), the surface temperature of the facility water inlet pipe (15b) becomes relatively low due to the facility water (17b) passing through the facility water inlet pipe (15b). During the heat radiation stop of (17), the stagnant water in the facility water inlet pipe (15b) causes the surface temperature of the facility water inlet pipe (15b) to become relatively low. It shields the radiant heat from the bypass inlet case (15a) and suppresses the heating of the engine cooling air (7f) passing through the air inlet (9a).

As shown in FIG. 3, this engine includes a cylinder head (1), an exhaust pipe (20) assembled to the cylinder head (1), and a heat insulating cover (21) covering the exhaust pipe (20) from its surroundings. and a belt tensioner (22) arranged on the side facing the end wall (21a) of the heat insulating cover (21).
As shown in FIG. 3, this engine consists of a (front) engine suspension fitting (23) assembled to the cylinder head (1) and a (front) end wall (21a) of the heat shield cover (21). The heat shield plate (24) is led out from the (front) engine hanging hardware (23) and is connected to the (front) end wall (21a) of the heat shield cover (21). Located between the belt tensioners (22).
The exhaust pipe (20) is an exhaust manifold (20a).

In this engine, radiant heat from the (front) end wall (21a) of the heat shield cover (21) is blocked by the heat shield plate (24), and heat accumulation in the heat shield plate (24) Since heat is radiated from both the belt tensioner (22) and the (forward) engine hanging hardware (23), the temperature rise of the belt tensioner (22) can be suppressed.

As shown in FIG. 7, the (front-side) sling fitting (23) is arranged on the front side of the cylinder head (1). It has a rearward engine suspension fitting (23c) facing the (forward) suspension fitting (23).

As shown in FIG. 4, this engine is equipped with an axial engine cooling fan (7). A (forward) engine hanger (23) is arranged at a position overlapping the blade (7a).
In this engine, the engine cooling air (7g) generated by the engine cooling fan (7) is blown into the exhaust side air blowing area (7d) around the engine hanging hardware (23) overlapping the blades (7a) (closer to the front). A large amount of heat is supplied to the (front) engine hanging hardware (23) to promote heat dissipation.

As shown in FIGS. 3 and 4, in this engine, the (forward) engine hanging hardware (23) is a linear guide portion ( 23a) and a cooling air receiving portion (23b) bent from the edge of the rectilinear guide portion (23a).
In this engine, the engine cooling air (7g) is received by the cooling air receiving portion (23b), and the heat dissipation of the engine suspension fitting (23) is promoted.
Further, in this engine, the bending of the cooling air receiving portion (23b) from the rectilinear guide portion (23a) makes it possible to increase the strength of the (forward) engine suspension fitting (23).

As shown in FIG. 3, in this engine, the heat shield plate (24) has an extended portion (24a) ( 24b), and as shown in FIG. 4, the engine cooling fan (7) is located between the cylinder head (1) and the belt tensioner (22) when viewed parallel to the central axis (8a) of the crankshaft (8). ) is provided with a cooling air introduction gap (25) that overlaps with the blade (7a) of ).
As shown in FIG. 4, in this engine, the engine cooling air (7g) generated by the engine cooling fan (7) passes through the cooling air introduction gap (25) overlapping the blades (7a) to the exhaust side air blow area (7d). A large amount of heat is supplied to the heat shield plate (24), and the heat of the heat shield plate (24) is radiated from the wide heat dissipation surface extended by the extensions (24a) and (24b) shown in FIG. is high.
The extensions 24a and 24b consist of an upper extension 24a and a lower extension 24b.

As shown in FIG. 3, in this engine, the extended portion (24a) of the (upper) heat shield plate (24) is bent toward the downstream side in the blowing direction of the air passage (9) of the engine cooling fan (7). and is inclined with respect to the blowing direction of the air blowing passage (9b) on the exhaust side.
In this engine, the inclination of the (upper) extension part (24a) reduces the flow path resistance of the exhaust-side blowing passage (9b), and the heat shield plate (24) in the exhaust-side blowing passage (9b) Increases cooling efficiency.

As shown in FIG. 3, in this engine the belt tensioner (22) is the generator (26).
In this engine, since the temperature rise of the generator (26), which is susceptible to thermal deterioration and thermal damage, is suppressed, the effect of suppressing thermal deterioration and thermal damage becomes apparent.
An alternator is used for the generator (26).

(1) Cylinder head (1a) Intake port (1b) Head cooling water jacket (1c) Engine cooling water (1d) Engine cooling water (2) Cylinder (2a) Cylinder Central axis (2b) Cylinder cooling water jacket (2c) Crank chamber (3) Intake manifold (3a) Collector (3b) Branch (3c) Blow-by gas inlet ( 4) Fuel injector (5) Delivery pipe (5a) Peripheral wall (5b) Liquid fuel (6) Gas mixer (7) Engine cooling fan (7a) Blade (7b) Rotation center (7c) Fan center imaginary line (7d) Exhaust side air blowing area (7e) Fan pulley (7f) Engine cooling air (7g) Engine cooling air (7h) Base part (8)...Crankshaft, (8a)...Center axis, (9)...Blower path, (9a)...Blower inlet, (9b)...Blower path on the exhaust side.

(10) Gas regulator (11) PCV system (12) Fresh air introduction case (13) Plug cap (14) Head cooling water discharge case (14a) Thermostat chamber (14b) Bypass tube (14c) Engine cooling water (14d) Thermostat valve (14e) Radiator side outlet (14f) Bypass side outlet (15) Water pump (15a) Bypass inlet case (15b) Radiating water inlet pipe (15c) Radiating water inlet (16) Radiator (16a) Radiating water (17) Air conditioner (17a) Radiator (18) Radiator Inlet side hose, (19)...Radiator outlet side hose.

(20) exhaust pipe (21) heat shield cover (21a) end wall (22) belt tensioner (22a) fulcrum (22b) stay (22c) tension pulley (22d) ) Belt cover, (23) Front engine hanging hardware, (23a) Straight guide part, (23b) Cooling air receiving part, (23c) Rear engine hanging hardware, (24) Heat shield Plate (24a) Extension portion (24b) Extension portion (25) Cooling air introduction gap (26) Generator (27) Cylinder block (28) Cylinder head cover (29) front case.

(30) Flywheel housing (31) Oil pan (32) Throttle body (33) Air cleaner (33a) Air (33b) Fresh air (34) Liquid fuel tank ( 34a) Liquid fuel, (35) Liquid fuel supply pump, (36) Liquefied gas fuel source, (36a) Liquefied gas fuel, (37) Vaporizer, (37a) Gas fuel, (38) Fuel Switching operation device, (38a)...Fuel switching operation lever, (39)...Electronic control unit, (39a)...Engine ECU.

(40) Ignition coil (42) Breather chamber (42a) Blow-by gas (43) PCV valve (44) Blow-by gas lead-out tube (45) Fresh air lead-out tube (46)... Oil pump, (47) ... oil filter, (48) ... oil cooler.

Claims (10)

Equipped with a plurality of fuel injectors (4), a delivery pipe (5) for distributing liquid fuel (34a) to the plurality of fuel injectors (4), and a gas mixer (6), switching between liquid fuel operation and gas fuel operation. During liquid fuel operation, the liquid fuel (34a) is injected from the fuel injector (4) into the air (33a) to form an air-fuel mixture, and during gas fuel operation, the air (33a) is mixed with the gas mixer (6). In a dual fuel engine in which gas fuel (37a) is mixed to form a mixture,
Equipped with an intake manifold (3), a cylinder head cover (28), and an axial engine cooling fan (7), the intake manifold (3) is seen in a direction parallel to the central axis (8a) of the crankshaft (8). ) and the cylinder head cover (28), the entirety of the delivery pipe (5) is positioned so as to overlap the blades (7a) of the engine cooling fan (7), and the periphery of the delivery pipe (5) forms an air passage (9). A gas mixer (6) is attached to the end of the collector (3a) of the intake manifold (3). A dual fuel engine characterized by The dual fuel engine of claim 1, wherein
A dual fuel engine characterized in that a peripheral wall (5a) of a delivery pipe (5) is formed of sheet metal. In the dual fuel engine of claim 2,
A dual fuel characterized in that the peripheral wall (5a) of the delivery pipe (5) is a rectangular tube, one side of which is fitted with a fuel injector (4), and the remaining three sides face an air duct (9). engine. In the dual fuel engine according to any one of claims 1 to 3,
When viewed in a direction parallel to the central axis (8a) of the crankshaft (8), the delivery pipe (5) is positioned so as to overlap the leading end half of the vane (7a) of the engine cooling fan (7). A dual fuel engine characterized by In the dual fuel engine according to any one of claims 1 to 4,
A dual fuel engine, characterized in that a gas regulator (10) is connected to a gas mixer (6), and the gas regulator (10) faces an air inlet (9a) of an air duct (9) from its peripheral side. In the dual fuel engine according to any one of claims 1 to 5,
A fresh air introduction case (12) for a PCV system (11) is provided, and the fresh air introduction case (12) faces an air inlet (9a) of an air duct (9) from its peripheral side. dual fuel engine. In the dual fuel engine according to any one of claims 1 to 6,
A dual fuel engine comprising a plug cap (13) of an ignition plug, wherein the outer peripheral surface of the plug cap (13) of the ignition plug faces an air passage (9). In the dual fuel engine according to any one of claims 1 to 7,
A head cooling water outlet case (14) attached to the cylinder head (1) is provided,
When viewed in a direction parallel to the central axis (8a) of the crankshaft (8), a fan central imaginary line (7c) parallel to the cylinder central axis (2a) and passing through the rotation center (7b) of the engine cooling fan (7) ), and an exhaust-side blast area located on the opposite side of the blast inlet (9a) of the intake-side blast passage (9) around the delivery pipe (5) with the fan center imaginary line (7c) as a boundary. A dual fuel engine characterized in that, assuming (7d), a head cooling water lead-out case (14) is arranged in an exhaust-side blowing area (7d). A dual fuel engine as claimed in claim 8,
A thermostat chamber (14a) provided in the head cooling water lead-out case (14), a bypass tube (14b) led out from the thermostat chamber (14a), and a water pump (15) connected to the bypass tube (14b). A bypass inlet case (15a) is provided so that the engine cooling water (14c) in the thermostat chamber (14a) bypasses the radiator (16) and is drawn into the bypass inlet case (15a) of the water pump (15). is,
An engine cooling fan (7) has a blade mounting base (7h) on the center side and blades (7a) projecting radially from the peripheral edge of the blade mounting base (7h). A dual fuel engine characterized in that the bypass inlet case (15a) of the water pump (15) is positioned so as to overlap the vane mounting substrate (7h) of the engine cooling fan (7) when viewed in a parallel direction. . A dual fuel engine as claimed in claim 9,
Equipped with a facility water inlet pipe (15b) attached to a bypass inlet case (15a) of a water pump (15) and a head cooling water jacket (1b) of a cylinder head (1). The engine cooling water (1c) is radiated by the radiator (17a) of the air conditioner (17) and turned into facility water (17b). ) is configured to be sucked into the bypass inlet case (15a) of
A facility water inlet pipe (15b) is arranged closer to the delivery pipe (5) than the thermostat chamber (14a) and the bypass inlet case (15a) when viewed in a direction parallel to the central axis (8a) of the crankshaft (8). A dual fuel engine characterized by:

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