A multi-cylinder engine wherein a direction in which a crank shaft spans is a front and rear direction and a widthwise direction of a cylinder head (1) perpendicular to the front and rear direction is a lateral direction, the multi-cylinder engine comprising the cylinder head (1) which has one lateral side to which an intake-air distributing passage wall (2) and has the other lateral side to which an exhaust-gas converging passage wall (3), a common rail (10) being arranged around the cylinder head (1). In this multi-cylinder engine, the common rail (10) is arranged immediately lateral of the intake-air distributing passage wall (2), thereby positioning the intake-air distributing passage wall (2) between the cylinder head (1) and the common rail (10). Preferably, an intake-air inlet pipe (11) is made to stand up at an upper portion of the intake-air distributing passage wall (2) and is provided with an intake-air flange portion (12), which is positioned just above the common rail (10).

BACKGROUND OF THE INVENTION

The present invention concerns a multi-cylinder engine and more particularly, relates to a multi-cylinder engine able to inhibit a common rail from being damaged.

There is a conventional example of the multi-cylinder engine which comprises a cylinder head having one lateral side surface onto which an intake-air distributing passage wall is attached and having the other lateral side surface onto which an exhaust-gas converging passage wall is attached, with a common rail arranged around the cylinder head as well as the present invention, on the assumption that a direction where a crank shaft spans is taken as a front and rear direction and that a widthwise direction of the cylinder head perpendicular to the front and rear direction is deemed as a lateral direction.

However, in the conventional multi-cylinder engine, the common rail is not sufficiently isolated from the cylinder head, as indicated in Japanese Patent Application Laid-Open (Kokai) No. 2001-227407 (seeFIGS. 1 and 3), to result in entailing problems.

The conventional technique has the following problem.

<Problem> The common rail is easily damaged.

The common rail is not so sufficiently isolated from the cylinder head that combustion heat of the engine is readily conducted to the common rail. Thus the common rail is easily damaged by overheating.

SUMMARY OF THE INVENTION

The present invention has an object to provide a multi-cylinder engine able to solve the above-mentioned problem and more specifically a multi-cylinder engine capable of inhibiting the common rail from being damaged.

The featuring matter of the invention according to a first aspect is as follows.

As illustrated inFIG. 1, a direction where a crank shaft spans is defined as a front and rear direction and a widthwise direction of a cylinder head1perpendicular to the front and rear direction is specified as a lateral direction. Then a multi-cylinder engine comprises the cylinder head1having one lateral side surface onto which an intake-air distributing passage wall2is attached and having the other lateral side surface onto which an exhaust-gas converging passage wall3is attached, with a common rail10arranged around the cylinder head1, wherein

as shown inFIG. 4, the common rail10is arranged just laterally of the intake-air distributing passage wall2, thereby positioning the intake-air distributing passage wall2between the cylinder head1and the common rail10.

(Effect of the Invention)

(The invention of the First Aspect)

<Effect> It is possible to prohibit the common rail from being damaged.

As illustrated inFIGS. 1 and 4, the common rail10is arranged just laterally of the intake-air distributing passage wall2, thereby positioning the intake-air distributing passage wall2between the cylinder head1and the common rail10. Thus the intake-air distributing passage wall2isolates the common rail10from the cylinder head1with the result of hardly conducting the combustion heat of the engine to the common rail10. This prevents the overheating of the common rail10and therefore inhibits the common rail10from being damaged by the overheating.

(The invention of a second aspect)

<Effect> It is possible to inhibit the common rail from being damaged.

It offers the following effect in addition to that of the invention according to the first aspect.

As shown inFIGS. 1 and 4, an intake-air inlet pipe11is made to stand up at an upper portion of the intake-air distributing passage wall2and is provided with an intake-air flange portion12. This intake-air flange portion12is positioned just above the common rail10. In consequence, at the time of manufacturing the engine or effecting the maintenance, even if parts, tools or the like substances fall in an upper area of the engine, the intake-air flange portion12can receive those substances before they collide against the common rail10immediately from above. This results in the possibility of inhibiting the common rail10from being damaged by the collision of the substances thereagainst just from above.

(Invention of a third aspect)

It offers the following effect in addition to that of the invention according to the first aspect or the second aspect.

<Effect> It is possible to inhibit the common rail from being damaged.

As shown inFIGS. 1 and 4, an EGR-gas inlet pipe13is made to stand up at the upper portion of the intake-air distributing passage wall2and has an upper portion provided with a gas flange portion14. This gas flange portion14is positioned just above the common rail10. In consequence, at the time of manufacturing the engine or effecting the maintenance, even if parts, tools or the like substances fall in the upper area of the engine, the gas flange portion14can receive those substances before they collide against the common rail10immediately from above. This results in the possibility of inhibiting the common rail10from being damaged by the collision of the substances thereagainst just from above.

(Invention of a fourth aspect)

It offers the following effect in addition to that of the invention according to the third aspect.

<Effect> It is possible to prohibit an EGR valve from being damaged.

As illustrated inFIGS. 1,3and4, the gas flange portion14is positioned at the back of an engine cooling fan6and an EGR valve case8is attached to the gas flange portion14, so that engine cooling air produced by the engine cooling fan6blows against the gas flange portion14. Therefore, the heat of the EGR gas is diffused from the EGR valve case8into the engine cooling air through the gas flange portion14to result in lowering the temperature of the EGR gas. This inhibits the overheating of the EGR valve with the result of being able to prohibit the EGR valve from being damaged by the overheating.

<Effect> It can highly reduce Nox.

The heat of the EGR gas is diffused from the EGR valve case8into the engine cooling air through the gas flange portion14to lower the temperature of the EGR gas. This enables Nox to be highly reduced.

<Effect> Maintenance can be made easily.

As illustrated inFIGS. 1,3and4, the gas flange portion14is positioned just above the common rail10and the EGR valve case8is attached to the gas flange portion14. Accordingly, the maintenance can be performed for the common rail10and the EGR valve case8all together on the same lateral side of the engine and therefore can be effected easily.

<Invention of a fifth aspect>

It offers the following effect in addition to that of the invention according to the fourth aspect.

<Effect> It can more enhance the ability of inhibiting the EGR valve from being damaged.

As illustrated inFIGS. 3 and 4, the gas flange portion14has an under surface inclined rearwards downwardly, thereby enabling the engine cooling air to blow against the gas flange portion14efficiently with the result of inhibiting the overheating of the EGR valve. Thus it is possible to more enhance the ability of prohibiting the EGR valve from being damaged by the overheating.

<Effect> It is possible to more enhance the ability of reducing Nox.

As illustrated inFIGS. 3 and 4, the gas flange portion14has the under surface inclined rearwards downwardly, thereby allowing the engine cooling air to blow against the gas flange portion14efficiently with the result of lowering the temperature of the EGR gas. Thus the ability of reducing Nox can be more enhanced.

<Effect> It is possible to inhibit the common rail from being damaged.

As exemplified inFIGS. 3 and 4, the engine cooling air is guided by the under surface of the gas flange portion14so as to blow against the common rail10. This prohibits the overheating of the common rail10to entail the possibility of inhibiting the common rail10from being damaged by the overheating.

(Invention of a Sixth Aspect)

It offers the following effect in addition to that of the invention according to any one of the third to fifth aspects.

<Effect> It is possible to inhibit a fuel supply pump from being damaged.

As illustrated inFIGS. 1,3and4, attached to the gas flange portion14is the EGR valve case8, to which a valve actuator15is attached. This valve actuator15is positioned just above a fuel supply pump16. Therefore, at the time of manufacturing the engine or performing the maintenance, even if parts, tools or the like substances fall, the valve actuator15can receive those substances before they collide against the fuel supply pump16. Thus it is possible to inhibit the fuel supply pump16from being damaged by the collision of the substances thereagainst immediately from above.

<Effect> Maintenance can be effected easily.

As exemplified inFIGS. 1,3and4, the gas flange portion14is positioned just above the common rail10. Attached to the gas flange portion14is the EGR valve case8, to which the valve actuator15is attached. Further, the valve actuator15is arranged just above the fuel supply pump16. Thus maintenance can be performed for the common rail10, the EGR valve case8, the valve actuator15and the fuel supply pump16all together on the same lateral side of the engine and therefore can be effected easily.

(Invention of a Seventh Aspect)

It offers the following effect in addition to that of the invention according to any one of the first to sixth aspects.

<Effect> It is possible to inhibit the common rail from being damaged.

As exemplified inFIGS. 3 and 4, a cooling water pump17is attached to a front portion of the engine and has an inlet pipe portion18positioned just in front of the common rail10ahead thereof. In consequence, at the time of producing the engine or effecting the maintenance, even if parts, tools or the like substances approach from the just front portion of the common rail10ahead thereof, the inlet pipe portion18of the cooling water pump17can receive those substances before they collide against the common rail10from the just front portion of the common rail10ahead thereof. Thus it is possible to prevent the common rail10from being damaged by the collision of the substances thereagainst just from the front portion of the common rail10ahead thereof.

(Invention of an Eighth Aspect)

It offers the following effect in addition to that of the invention according to any one of the first to seventh aspects.

<Effect> It is possible to inhibit the common rail from being damaged.

As shown inFIGS. 3 and 4, a fuel filter19is arranged just laterally of the cylinder head1and positioned immediately at the back of the common rail10. Thus at the time of producing the engine or effecting the maintenance, even if parts, tools or the like substances approach just from the back of the common rail10, the fuel filter19can receive those substances before they collide against the common rail10just from the back of the latter. Therefore, it is possible to inhibit the common rail10from being damaged by the collision of the substances thereagainst just from the back of the common rail10.

<Effect> Maintenance can be facilitated.

As exemplified inFIGS. 3 and 4, the fuel filter19is disposed immediately at the back of the common rail10. Thus the maintenance can be performed for the common rail10and the fuel filter19all together on the same lateral side of the engine and therefore can be effected easily.

(Invention of a Ninth Aspect)

It offers the following effect in addition to that of the invention according to any one of the first to eighth aspects.

<Effect> It is possible to inhibit the common rail from being damaged.

As exemplified inFIGS. 1,3and4, a cylinder block5has a lateral wall provided with a seat20for attaching an oil filter21. The oil filter21is attached to this oil-filter attaching seat20, which is positioned just below the common rail10. Thus at the time of manufacturing the engine and performing the maintenance, even if parts, tools or the like substances approach the common rail10just from below, the oil-filter attaching seat20can receive those substances before they collide against the common rail10just from below. Therefore, it is possible to inhibit the common rail10from being damaged by the collision of the substances thereagainst just from below the common rail10.

<Effect> Maintenance can be facilitated.

Since the oil-filter attaching seat20is positioned just below the common rail10, maintenance can be performed for the common rail10and the oil filter21all together on the same lateral side of the engine and therefore can be effected easily.

(Invention of a Tenth Aspect)

It offers the following effect in addition to that of the invention according to any one of the first to ninth aspects.

<Effect> It is possible to make an EGR cooler compact.

As shown inFIGS. 1 to 3, an EGR gas lead-out pipe7conducted out of an EGR cooler4is arranged rearwards of the engine cooling fan6in order that the engine cooling air produced by the engine cooling fan6might blow against the EGR gas lead-out pipe7. Therefore, it is possible to alleviate the cooling load of the EGR cooler4in proportion to the EGR gas to be air-cooled by the EGR gas lead-out pipe7. This invites the possibility of making the EGR cooler4compact.

(The invention of an Eleventh Aspect)

It offers the following effect in addition to that of the invention according to the tenth aspect.

<Effect> It is possible to inhibit an EGR valve from being damaged.

As shown inFIGS. 1 to 3, an EGR valve case8is arranged downstream of the EGR gas lead-out pipe7. Thus the EGR gas is cooled by the EGR cooler4and is air-cooled by the EGR gas lead-out pipe7and then reaches the EGR valve case8. This prohibits the overheating of the EGR valve with the result of inhibiting the EGR valve from being damaged by the overheating.

(Invention of a Twelfth Aspect)

It offers the following effect in addition to that of the invention according to the tenth or eleventh aspect.

<Effect> It is possible to make a radiator compact.

As exemplified inFIGS. 1 to 3, a cooling water lead-out pipe9, which is conducted out of an EGR cooler4, is disposed at the back of the engine cooling fan6so that the engine cooling air generated by the engine cooling fan6blows against the cooling water lead-out pipe9. Therefore, it is possible to reduce the cooling load of a radiator (not shown) in proportion to the cooling water, which has been flowed out of the EGR cooler4, to be air-cooled by the cooling water lead-out pipe9. This invites the possibility of making the radiator compact.

MOST PREFERRED EMBODIMENT OF THE INVENTION

An embodiment of the present invention is explained based on the attached drawings.FIGS. 1 to 4show an engine according to the embodiment of the present invention. In this embodiment, an explanation is given for a water-cooled vertical straight multi-cylinder diesel engine.

The embodiment of the present invention is outlined as follows.

As shown inFIGS. 2 to 4, a cylinder head1is assembled to an upper portion of a cylinder block5and has an upper portion to which a head cover22is assembled. The cylinder block5has a lower portion to which an oil pan23is assembled and has a front portion to which a gear case24is assembled. Further, the cylinder block5has a rear portion to which a flywheel housing25is assembled.

A cooling water pump17is attached to the cylinder block5above the gear case24. The cooling water pump17has an input shaft to which an engine cooling fan6is attached. The cooling water pump17and the engine cooling fan6are driven by a crank shaft through a belt transmission device (not shown). A radiator (not shown) is arranged ahead of the engine cooling fan6. When the engine cooling fan6is rotated, cooling air is sucked from a front portion of the radiator thereinto and is outputted as cooling exhaust-gas which comes to be engine cooling air.

This engine is equipped with an EGR device and with a fuel injection device of common-rail type. The EGR device reduces part of the exhaust-gas into intake air. The fuel injection device of common-rail type accumulates the fuel having its pressure increased by a fuel supply pump16in its common rail10. An injector has an electromagnetic valve to be opened and closed through electronic control so as to adjust the amount of the fuel to be injected at the time of fuel injection of every cylinder.

The EGR device is devised as follows.

As shown inFIG. 1, a direction where the crank shaft spans is a front and rear direction and a widthwise direction of the cylinder head1perpendicular to this front and direction is a lateral direction. The cylinder head1has a left side surface to which an intake-air distributing passage wall2is attached and has a right side surface to which an exhaust-gas converging passage wall3is attached. An EGR cooler4is interposed between an exhaust-gas converging passage and an intake-air distributing passage. The intake-air distributing passage wall2is an intake air manifold and the exhaust-gas converging passage wall3is an exhaust-gas manifold.

As exemplified inFIGS. 1 to 3, the EGR cooler4spans in the front and rear direction laterally of the cylinder block5and the exhaust-gas converging passage wall3is positioned just above this EGR cooler4. The position just above the EGR cooler4refers to a position which is above the EGR cooler4and overlaps the same, as shown inFIG. 1, when seen in a direction parallel to a cylinder center axis26. Further, if seen in the direction parallel to the cylinder center axis26, the EGR cooler4is arranged so as not to project laterally of the exhaust-gas converging passage wall3.

As shown inFIGS. 1 to 3, one side where the engine cooling fan6is present is defined as the front and the opposite side is determined as the rear. An EGR gas lead-out pipe7conducted out of the EGR cooler4is arranged rearwards of the engine cooling fan6in order that the engine cooling air produced by the engine cooling fan6might blow against the EGR gas lead-out pipe7. An EGR valve case8is positioned downstream of the EGR gas lead-out pipe7. A cooling water lead-out pipe9conducted out of the EGR cooler4is disposed rearwards of the engine cooling fan6so that the engine cooling air generated by the engine cooling fan6might blow against the cooling water lead-out pipe9. Either of the EGR gas lead-out pipe7and the cooling water lead-out pipe9is arranged immediately rearwards of the engine cooling fan6.

The position immediately rearwards of the engine cooling fan6, as sown inFIG. 3, refers to a position which is at the back of the engine cooling fan and overlaps the same when seen in a direction parallel to a center axis27of the crank shaft. As illustrated inFIG. 3, the cooling water lead-out pipe9has a lead-out end made to communicate with a sucking side of the cooling water pump17. As shown inFIG. 2, a cooling water lead-in pipe28conducted out of the EGR cooler4has a lead-out end made to communicate with a cylinder jacket (not shown) within the cylinder bock5.

The fuel injection device of common-rail type is devised as follows.

As represented inFIGS. 1 and 4, the common rail10is arranged just laterally of the intake-air distributing passage wall2, thereby positioning the intake-air distributing passage wall2between the cylinder head1and the common rail10. The position just lateral of the intake-air distributing passage wall2refers to, as shown inFIG. 4, a position which is opposite to the cylinder head1and overlaps the intake-air distributing passage wall2when seen in a direction perpendicular to the cylinder center axis26and to the center axis27of the crank shaft. An intake-air inlet pipe is made to stand up at an upper portion of the intake-air distributing passage wall2and is provided with an intake-air flange portion12. This intake-air flange portion12is positioned just above the common rail10. The position just above the common rail10refers to a position which is above the common rail and overlaps the same as shown inFIG. 1when seen in the direction parallel to the cylinder center axis26. An intake-air connection pipe30is attached to the intake-air flange portion12through an intake air heater29. Connected to this intake-air connection pipe30is a lead-out end of an intake air pipe (not shown) conducted out of a supercharger31.

As shown inFIGS. 1 and 4, an EGR-gas inlet pipe13is made to stand up at the upper portion of the intake-air distributing passage wall2. A gas flange portion14is provided above the EGR gas inlet pipe13and is positioned just above the common rail10. Attached to the EGR gas inlet pipe13is an EGR gas connection pipe32. This EGR gas connection pipe32has an upper end portion to which the gas flange portion14is attached.

As shown inFIGS. 1,3and4, the gas flange portion14is positioned at the back of the engine cooling fan6. The EGR valve case8is attached to this gas flange portion14so that the engine cooling air generated by the engine cooling fan6might blow against the gas flange portion14. The gas flange portion14has an under surface inclined rearwards downwardly in order that the engine cooling air might be guided by the under surface of the gas flange portion14to blow against the common rail10. The EGR valve case8is attached to the gas flange portion14and a valve actuator15is attached to the EGR valve case8. The valve actuator15is positioned just above a fuel supply pump16. The position just above the fuel supply pump16refers to a position which is above the fuel supply pump16and overlaps the same, when seen in the direction parallel to the cylinder center axis26.

As represented inFIGS. 1,3and4, the cooling water pump17is attached to the front portion of the engine and has an inlet pipe portion18positioned in the just front of the common rail10ahead thereof. The inlet pipe portion18is connected to a lead-out end of a cooling water return pipe (not shown) conducted out of the radiator. The position in the just front of the common rail10ahead thereof refers to a position which is in front of the common rail10and overlaps the same as shown inFIG. 3when seen in a direction parallel to the center axis27of the crank shaft.

As illustrated inFIGS. 1,3and4, a fuel filter19is arranged immediately lateral of the cylinder head1and is positioned immediately rearwards of the common rail10. The cylinder block5has a lateral wall provided with a seat20for attaching an oil filter21. The oil filter21is attached to the oil-filter attaching seat20, which is positioned just below the common rail10. The position immediately rearwards of the common rail10refers to a position which is at the back of the common rail10and overlaps the same, as shown inFIG. 3when seen in the direction parallel to the center axis27of the crank shaft. The position just below the common rail10refers to a position which is below the common rail10and overlaps the same as shown inFIG. 1when seen in the direction parallel to the cylinder center axis26.