JPH10122039A - Direct injection diesel engine - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To improve the fuel efficiency of a direct injection diesel engine by reducing the exhaust extrusion loss. An intake port provided with a cylinder head of an engine is arranged so that an intake swirl is generated in a cylinder during an intake stroke. On the other hand, two or more exhaust ports are provided, and at least one of the exhaust ports is provided. Are arranged substantially tangential to the swirl flow. Further, the two or more exhaust ports are arranged parallel to each other, and preferably are formed to extend linearly obliquely upward.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a direct injection diesel engine.

[0002]

2. Description of the Related Art FIG. 3 shows an example of the configuration of a conventional direct injection diesel engine mounted on a vehicle such as a truck.
4 and a conceptual plan view of FIG. In the drawing, reference numeral 10 denotes a plurality of cylinders 1 arranged side by side, each center line being included in a center plane OO perpendicular to the paper surface of FIG.
Reference numeral 14 denotes a cylinder head mounted on the upper end of the crankcase 10 in the figure via a head gasket 16.

[0003] The cylinder 12 is formed by a cylinder liner 18 fitted in the crankcase 10, and a connecting rod 20 is provided in the cylinder liner 18.
A piston 22 connected to a crankshaft (not shown) via the shaft 22 is slidably fitted. At the top of the piston 22, a combustion chamber 24 of a toroidal type or any other shape is recessed.

[0004] As best shown in the conceptual plan view of FIG. 4, in the cylinder head 14, each cylinder 12 for each, each two being controlled communication between the cylinder 12 by the exhaust valve V _e Exhaust ports 26a and 26b are provided, and both exhaust ports 26a and 26b are joined on the downstream side and connected to the exhaust manifold 28. (Note that the exhaust ports 26a and 26b may be connected to the exhaust manifold 28 as separate passages without merging on the downstream side as shown in the figure.

Further, in the cylinder head 14, each cylinder 12 for each, two intake ports 30a and 30b respectively the intake valves V _{i (illustration} is omitted) controlled communication between the cylinder 12 by the These intake ports 30 a and 30 b are connected at their upstream ends to an intake manifold 32. Above intake manifold 3
2 is mounted on one side of the cylinder head 14 with respect to the center plane OO of the crankcase 10, and the exhaust manifold 28 is mounted on the cylinder head 1 with respect to the center plane OO.
4 is mounted on the other side.

The downstream portion of the intake ports 30a and 30b adjacent to the cylinder 12 swirls intake air flowing through the intake ports 30a and 30b and flowing into the cylinder 12 during an intake stroke, and is indicated by an arrow S in FIG. It is formed as a helical port with a swirl chamber that creates a swirl of intake air.

Further, as shown in FIG. 4, in the case of many truck diesel engines, usually six cylinder heads 14 are provided on the cylinder head 14 while avoiding the exhaust ports 26a and 26b and the intake ports 30a and 30b. A head bolt hole 34 is provided, and a head bolt 36 inserted from above in FIG.
By screwing into a female screw hole 38 provided in the outer peripheral portion of the cylinder of the crankcase 10, the cylinder head 1
4 is configured to be tightly fixed to the crankcase 10.

In the above conventional diesel engine,
During the intake stroke, the intake in the intake manifold 32 is performed by two intake ports 30a and 30b as the piston 22 descends.
Flows into the cylinder 12 to form a swirl of intake air as shown by an arrow S in FIG. During the subsequent compression stroke, the intake air in the cylinder 12 is compressed while maintaining the swirl S, and turns into high-temperature and high-pressure intake in a combustion chamber 24 recessed at the top of the piston 22 near the compression top dead center.

Near the compression top dead center, fuel is injected into the combustion chamber 24 from a fuel injection valve (not shown) disposed near the extension of the cylinder center line of the cylinder head 14 to cause explosion and combustion. A combustion stroke is performed. During the exhaust stroke in which the piston 22 continues to rise, the cylinder 12
Combustion gas of the internal flows out the exhaust ports 26a and 26b as the exhaust manifold 28 from exhaust valves V _e which is opened as an exhaust.

Since the combustion gas and exhaust gas in the cylinder 12 swirl substantially in the same direction as the intake swirl S through the combustion stroke and the exhaust stroke, they flow into the exhaust ports 26a and 26b from the cylinder 12 in the exhaust stroke. exhaust, as indicated by the arrow E _a and E _b in FIG. 4, flows into the exhaust port 26a and 26b by changing the large direction. For this reason, the flow coefficients of the exhaust ports 26a and 26b are deteriorated, and the exhaust push-out loss in the exhaust stroke is increased, so that the fuel efficiency of the engine is deteriorated.

[0011]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned drawbacks of the conventional direct injection type diesel engine, and makes it possible to smoothly discharge combustion gas or exhaust gas in a cylinder to an exhaust port during an exhaust stroke. An object of the present invention is to provide a diesel engine of this type that can reduce extrusion loss and thereby improve fuel efficiency of the engine.

[0012]

SUMMARY OF THE INVENTION The present invention has been devised to achieve the above object, and has a crankcase having a plurality of cylinders arranged in a row, and a cylinder mounted on the crankcase and having intake air in each cylinder. A cylinder head having an intake port for supplying air and an exhaust port for exhausting exhaust of each cylinder; an intake manifold disposed on one side of a center plane including a center line of the plurality of cylinders and communicating with the intake port; An exhaust manifold arranged on the other side of the center plane and communicating with the exhaust port, the intake port is arranged to generate a swirl flow of intake air in the cylinder during an intake stroke, and the exhaust port is The present invention proposes a direct-injection diesel engine that is arranged to extend substantially tangentially to the swirl flow. With this configuration, the flow coefficient of the exhaust port can be improved, and the exhaust extrusion loss can be reduced.

In the present invention, it is preferable that two exhaust ports are provided for each cylinder and arranged substantially parallel to each other. With this configuration, a wide exhaust port passage area can be secured, and the length of the exhaust port in the cylinder head can be shortened to reduce heat loss. In the present invention, it is preferable that a head bolt for tightening the cylinder head to a crankcase is inserted from the lower deck side of the cylinder block and screwed to a portion of the cylinder head adjacent to the crankcase. By adopting a configuration in which the head bolts that tighten the cylinder head against the crankcase are inserted from the lower deck side of the cylinder block portion of the crankcase, contrary to the normal structure, the degree of freedom in the arrangement of the exhaust ports inside the cylinder head Can be greatly improved. Further, in the present invention, it is preferable that two or more exhaust ports are provided in each cylinder, and at least one of the exhaust ports is arranged substantially tangentially to the swirl flow. In order to increase the exhaust passage area and reduce the exhaust flow resistance, it is desirable to provide two or more exhaust ports in each cylinder. In this case, at least one exhaust port is required due to the arrangement of the exhaust ports in the cylinder head. It is advantageous to arrange the ports tangentially to the swirl flow in the cylinder.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the present invention will be described below with reference to a schematic longitudinal sectional view of FIG. 1 and a conceptual plan view of FIG. (Note that the same reference numerals are used for members and portions that are substantially the same as or correspond to the previous configuration described with reference to FIGS. 3 and 4.) The illustrated embodiment illustrates the present invention as an example. it is applied to a so-called 4-valve engine equipped with two intake valves V _i and two exhaust valves V _e. In particular, as best seen in the conceptual plan view of FIG. 2, each of the upstream ends provided in the cylinder head 14 is formed in the cylinder 12 among the intake ports 30 a and 30 b connected to the intake manifold 32. Intake port 30a on the downstream side with respect to swirl S
Is a so-called tangential port through which intake air flows out tangentially toward the inner peripheral surface of the cylinder 12.
No vortex chamber is provided in the downstream part of the port adjacent to 2.
On the other hand, the intake port 30b on the upstream side with respect to the swirl S is
A helical port provided with a vortex chamber for swirling intake air is formed in a downstream portion adjacent to the cylinder 12.

Of the two exhaust ports 26a and 26b provided in the cylinder head 14 and having respective downstream ends connected to the exhaust manifold 28, the exhaust port 26a on the upstream side with respect to the swirl S has a swirl flow. 1 and 2, and extends linearly outward and upward in the radial direction from the opening end to the cylinder 12, that is, obliquely upward as shown in FIGS. 1 and 2. Is formed,
The exhaust port 26b on the downstream side is arranged substantially parallel to the exhaust port 26a.

Further, the cylinder head 14 is provided with the cylinder head 14 shown in FIG.
As shown in FIG. 1, the lower end of the cylinder block 10a of the crankcase 10, that is, the lower deck 1
0b, the head bolt 36 inserted substantially parallel to the center plane including the cylinder axis is
Is screwed into a female screw hole 40 provided in a portion adjacent to the crankcase 10, that is, a lower portion of the cylinder head in the figure, and is tightened and fixed to the crankcase 10 via the head gasket 16. In the case of a diesel engine such as a truck, the head bolt 36
It is preferable to provide about six per cylinder from the viewpoint of ensuring the sealing performance of the combustion gas. Also, the exhaust port 26
By arranging the intake ports 30a and 30b so as to extend obliquely upward, as in the case of a and 26b,
The six female bolt holes 40 for head bolts can be easily arranged so as not to interfere with the intake ports 26a, 26b and the exhaust ports 30a, 30b.

[0017] In FIG. 1, reference numeral 42 is a cooling water chamber provided in the cylinder head 14, 44 is an intake valve spring for urging the intake valves V _i in the normally closed direction via the valve retainer 46, 48 Sets the exhaust valve _Ve to the valve retainer 50.
This is an exhaust valve spring that is normally urged in the closing direction via the valve.

The basic operation cycle of the diesel engine shown in FIGS. 1 and 2 is substantially the same as that of the conventional diesel engine, and therefore, the description thereof will not be repeated. In the intake stroke, the intake ports 30a and 30b
Form a swirl swirling around the centerline of the cylinder, as indicated by arrow S in FIG. 2, which swirl S persists during the compression and combustion strokes. .

Subsequently, in the exhaust stroke, the combustion gas or exhaust gas in the cylinder 12 is discharged to the exhaust ports 26a and 26b.
Is discharged to the outside air through the exhaust manifold 28. At this time, since the exhaust port 26a on the upstream side with respect to the swirl S is formed substantially tangentially to the swirl flow, an arrow E in FIG. _As shown by _a , the combustion gas or exhaust gas flowing into the port 26a has an extremely low inflow resistance, and also in the process of flowing through the port and reaching the exhaust manifold 28, the exhaust port 26a , The flow resistance is small. Further, the remaining combustion gas or exhaust gas in the cylinder 12 flows into the exhaust port 26b while slightly changing the direction of the streamline with respect to the swirl S, as shown by an arrow _Eb in the drawing. Since the change in the flow direction at the time of inflow is small, the inflow resistance is sufficiently small. Further, since the exhaust port 26b is arranged substantially parallel to the exhaust port 26a and substantially straight obliquely upward, the port There is an advantage that the flow resistance in the process from the inlet to the exhaust manifold 28 is extremely small.

As a result, the exhaust ports 26a and 26b
The integrated flow rate coefficient is improved as compared with the same type of conventional device, and the exhaust extrusion loss is reduced, so that the fuel efficiency of the engine can be improved. Since the flow resistance from the inlets of the exhaust ports 26a and 26b to the exhaust manifold 28 is essentially small, the flow path on the way does not necessarily have to be formed linearly. For the above reasons, the curve may be slightly curved, and the curve coefficient hardly deteriorates the flow coefficient.

However, by arranging the exhaust ports 26a, 26b linearly and in parallel to each other and extending obliquely upward as shown in the figure, the head ports are arranged below the cylinder block portion 10a of the crankcase 10. In conjunction with a special head bolt arrangement for tightening bolts 36, typically one
There is a space advantage that the exhaust ports 26a and 26b can be arranged while avoiding interference with the six head bolts 36 provided for each cylinder. Further, the exhaust ports 26a,
Since the thermal energy possessed by the combustion gas or exhaust gas flowing in the inside 26b can suppress the heat loss taken by the cylinder head 14 and the cooling water therein substantially to a minimum, the exhaust energy can be reduced downstream of the exhaust manifold 28. It is effectively recovered by a turbocharger (not shown) that includes an exhaust turbine located on the side, further improving the fuel efficiency of the engine,
There are additional advantages that can improve performance such as power.

The present invention is not limited to the embodiments shown in FIGS. 1 and 2, and various changes and modifications can be made within the scope of the claims of the present invention.
For example, the number of exhaust valves is not limited to two, but may be three or more, and one or more suitable number of intake valves may be provided. Further, the intake port 3 in FIG.
0a can also be a helical port.

[0023]

As described above, the direct injection diesel engine according to the present invention has a crankcase having a plurality of cylinders arranged in a row, and an intake air mounted on the crankcase and supplying intake air to each cylinder. A cylinder head having a port and an exhaust port for discharging exhaust gas from each cylinder; an intake manifold disposed on one side of a center plane including a center line of the plurality of cylinders and communicating with the intake port; An exhaust manifold arranged on the side and communicating with the exhaust port, wherein the intake port is arranged to generate a swirl flow of intake air in the cylinder during an intake stroke, and the exhaust port is provided with respect to the swirl flow. It is arranged so as to extend substantially tangentially. With this configuration, the flow coefficient of the exhaust port is improved, and the exhaust extrusion loss is reduced. Reduced to an advantage capable of improving the fuel economy of the engine.

In the present invention, the two exhaust ports are provided in each cylinder and arranged substantially parallel to each other, so that the exhaust ports can be easily arranged in the cylinder head. This has the effect of effectively improving the flow coefficient of exhaust gas and preserving exhaust energy. Further, a head bolt for tightening the cylinder head to the crankcase is inserted from the lower deck side of the cylinder block portion and screwed to a portion of the cylinder head adjacent to the crankcase, so that it is substantially tangential to swirl flow. There is an advantage that it is easy to arrange the two exhaust ports arranged in parallel with each other and in a straight line while avoiding interference with the head bolt.

[Brief description of the drawings]

FIG. 1 is a schematic longitudinal sectional view showing a preferred embodiment of the present invention.

FIG. 2 is a conceptual plan view showing an arrangement of intake and exhaust ports of the diesel engine shown in FIG.

FIG. 3 is a schematic longitudinal sectional view of a conventional direct injection diesel engine.

FIG. 4 is a conceptual plan view showing an arrangement of intake and exhaust ports of the diesel engine shown in FIG.

[Explanation of symbols]

10 ... Crankcase, 10a ... Cylinder block part,
10b lower deck, 12 cylinder, 14 cylinder head, 20 connecting rod, 22 piston, 24 combustion chamber, 26a and 26b exhaust port, 2
8 Exhaust manifold, 30a and 30b Intake port, 32 Intake manifold, 36 Head bolt, V
_e ... exhaust valve, V i _... intake valve.

Claims (4)

[Claims] A cylinder head having a plurality of arranged cylinders, an intake port mounted on the crankcase for supplying intake air to each cylinder, and an exhaust port for discharging exhaust gas from each cylinder; An intake manifold arranged on one side of a center plane including a center line of the plurality of cylinders and communicating with the intake port, and an exhaust manifold arranged on the other side of the center plane and communicating with the exhaust port, The intake port is arranged to generate a swirl flow of intake air in the cylinder during an intake stroke, and the exhaust port is arranged to extend substantially tangentially to the swirl flow. Direct injection diesel engine. 2. The direct-injection diesel engine according to claim 1, wherein two exhaust ports are provided for each cylinder and are arranged substantially in parallel with each other. 3. A head bolt for tightening the cylinder head to a crankcase is inserted from a lower deck side of a cylinder block and screwed to a portion of the cylinder head adjacent to the crankcase. The direct injection diesel engine according to claim 1 or 2. 4. The cylinder according to claim 1, wherein at least two exhaust ports are provided in each cylinder, and at least one of the exhaust ports is arranged substantially tangentially to the swirl flow. The direct injection diesel engine according to claim 2 or 3.