JP2000303846A - Multivalve intake engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate intake interference within a cylinder and to aim at high swirling. SOLUTION: In this multivalve intake engine, a plurality of intake ports are provided per cylinder, the intake port of a swirl direction upstream side and the downstream side intake port of the intake ports are made into a helical port 2 and a tangential port, respectively, and a valve guide boss within the helical port 2 is eliminated. As a result, outflow streams of both the ports become a swirl direction, intake interference is eliminated, and the helical port 2 is drawn to a valve stem 18 side of an intake valve 17. When a valve guide 16 within the helical port 2 is eliminated, the helical port 2 is further drawn. When the tangential port is made a straight tangential port, intake resistance is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a multi-valve intake type engine applied to a diesel engine or the like.

[0002]

2. Description of the Related Art A four-valve multi-valve intake engine is known which is provided with two intake ports and two exhaust ports for each cylinder and opens and closes them by intake valves and exhaust valves, respectively.

FIG. 5 shows a conventional example (see Japanese Patent Application Laid-Open No. 6-288240). The left side of the figure is the front of the engine, the right side is the back of the engine, an injector b is arranged at the center of the cylinder a, two exhaust ports c and c are arranged on the right side of the engine, and two intake ports d and e are arranged on the left side of the engine. . The front intake port d is a helical port, and the intake air is swirled in the same rotational direction as the swirl direction S and flows out into the cylinder a. The rear intake port e is a deformed tangential port, and the intake air is reversed in the swirl direction S by the concave portion f in the port and flows out into the cylinder a. Each port is opened and closed by an intake valve and an exhaust valve (not shown).

[0004]

By the way, in such a port layout, the intake air flowing out of the helical port d is clockwise and collides with the flow in the swirl direction S flowing out of the tangential port e. The swirl is weakened by the intake interference. In matching between a fuel injection system and a combustion system today, it is essential to obtain a high swirl at a high rotation speed. However, such a layout makes it impossible and causes smoke deterioration. In particular, a small direct injection diesel engine (hereinafter, referred to as a small DI) has a large demand for high rotation and high swirl, and such a layout cannot meet the demand. Further, the deformed tangential port e has a disadvantage that the passage resistance is larger than that of a normal straight tangential port.

[0005]

A multi-valve intake engine according to the present invention is provided with a plurality of intake ports per cylinder,
Among them, the intake port on the upstream side in the swirl direction is a helical port, the intake port on the downstream side is a tangential port, and the valve guide boss in the helical port is removed.

Here, it is preferable that the valve guide is further removed at a portion where the valve guide boss is removed.

Preferably, the tangential port is a straight tangential port.

The helical port is provided immediately upstream of the outlet, and is provided with a concave portion which is swollen toward the upstream in the swirl direction with respect to the outlet and reverses the introduced intake air in the swirl direction. The swirl direction is the same as that of the swirl direction, and the swirl direction is provided in the swirl direction. Is preferred.

The concave portion has a maximum bulging amount on a straight line along a tangential direction of the swirl passing through the center of the port outlet,
And the same rotational direction 0 as the swirl direction with respect to the straight line.
It is preferred to have the outlet in an angle range of 90 °.

[0010]

Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 4 shows a multi-valve intake engine according to the present invention.
FIG. 2 is a plan view schematically showing a four-valve engine.
As described above, two intake ports 1 and 2 and two exhaust ports 3 and 3 are provided for each cylinder, and these are opened and closed by intake valves and exhaust valves (not shown), respectively. The left side of the figure is the front of the engine, and the right side is the back of the engine. An injector 5 for performing fuel injection is arranged at the center of the cylinder 4.
Two exhaust ports 3, 3 are arranged on the right side of the engine, and two intake ports 1, 2 are arranged on the left side of the engine.

Although not shown, this engine is a multi-cylinder engine, and a plurality of (for example, four) engines are provided along the front-rear direction of the engine.
Are arranged in a row. The crankshaft and camshaft are also arranged along the front-rear direction of the engine. The intake ports 1 and 2 and the exhaust ports 3 and 3 are defined inside the cylinder head, and the injector 5 is also attached to the cylinder head. The cylinder 4 is partitioned and formed inside the cylinder block. The outlets of the intake ports 1 and 2 and the inlets of the exhaust ports 3 and 3 are opened facing the combustion chamber in the cylinder 4. These outlets and inlets are formed on the lower surface of the cylinder head.

Unlike the conventional example, the front intake port 1 is a normal straight tangential port having a constant passage area, and directs intake air from the entire port outlet 1a toward the downstream side in the swirl direction S and in the swirl tangential direction. To be drained to Hereinafter, the front intake port is referred to as a tangential port. Note that the swirl direction S here is a clockwise rotation direction.

On the other hand, the rear intake port 2 is a helical port having a shape similar to the conventional variant tangential port. Hereinafter, the rear intake port 2 is referred to as a helical port. The helical port 2 is disposed upstream of the tangential port 1 in the swirl direction S. The helical port 2 includes a concave portion 7 provided immediately upstream of the outlet 6, a winding portion 8 provided upstream of the concave portion 7, and a straight portion 9 provided upstream of the winding portion 8. .

An intake valve is disposed on the outlet 6 of the helical port 2 so as to be able to move up and down. FIG. 4 shows only the valve stem 10 of the intake valve. The valve stem 10 is the valve guide 1
1 and supported. Although not shown, the same applies to the tangential port 1 and the exhaust ports 3 and 3.

Here, the center of the cylinder is O ₄ , the center of the helical port exit is O ₂ , the straight line from the cylinder center O ₄ to the left is X, and the radial straight lines passing through O ₂ and O ₄ are L ₂ and O ₂ .
The straight line perpendicular ₂ as straight L ₂ L _2t, a straight line parallel to O ₂ as axis X L _2XT, the same line perpendicular to L _2xN.

Straight line L ₂ or helical port exit center O
Reference numeral ₂ is positioned on a straight line obtained by rotating the straight line X about the cylinder center O ₄ in the anti-swirl direction by about θ ₁ = 45 °. Recess 7 is provided swirl direction S upstream side of the straight line L _2, is swelled in a crescent shape toward the port outlet 6 in the swirl direction S upstream side. Crescent shape of the concave portion 7 is a symmetrical with respect to the straight line L _2t, the maximum bulging amount on the straight line L _2t. In particular, the straight line L _2t corresponds to the port exit center O
Coincides with the swirl tangent direction at position ₂ . Recess 7
Is substantially within the range of the port exit width B along the straight line _L2t .

The straight section 9 has a rear partition wall 12 connected to the valve guide 11. The connection position p becomes a boundary between the straight portion 9 and the winding portion 8. The winding portion 8 is wound around the valve stem 10 in the swirl direction S from the connection position p, and is connected to the concave portion 7. The winding portion 8 is also substantially contained within the range of the port exit width B along the straight line _L2t . Straight line L ₂
Is a boundary between the winding portion 8 and the concave portion 7, and on the straight line L ₂ , those connecting portions slightly project from the port outlet 6 inward and outward in the radial direction.

The helical port 2 has a straight portion 9
Has a substantially constant height over its entire length.
, The height is gradually lowered, and the outlet 6 reaches the lowest position. Then, the intake air flowing through the straight portion 9 is swirled by the winding portion 8 in the same rotational direction as the swirl direction S, and the swirl is maintained along the outer peripheral wall 13 of the concave portion 7, and the intake air flows toward the upstream side in the swirl direction S. The flow is reversed from the flow toward the downstream side of the swirl direction S, and flows out from the outlet 6 along the swirl direction S. In particular, a reservoir for the intake air flow is created in the concave portion 7, and the intake air is discharged from the outlet 6 using the momentum. Accordingly, the flow flowing out of the outlet 6 is a flow having a swirl component in the swirl direction S while following the swirl tangential direction. The substantial outlet of the concave portion 7 is within the angular range θ ₂ rotated from the straight line L _{2t in the} swirl direction S by 0 to 90 ° (that is, the latter half of the flow in the concave portion 7).

Here, a partition wall 14 having a thickness t is formed between the injector 5 and the helical port 2. Conversely, the helical port 2 required to secure the partition 14
It was adopted. That is, the helical port d of the conventional shape shown in FIG. 5 is configured to protrude to the upper left in the figure with respect to the port outlet. If this is replaced with the helical port 2 at the lower right of FIG. Can not be laid out. Therefore, the partition wall 14 is secured by adopting such a port layout.

Further, by adopting such a port layout, it is possible to avoid intake interference. That is, since both the tangential port 1 and the helical port 2 allow the intake air to flow out in the swirl direction S, the swirl does not weaken due to the collision of the intake air with each other, and a high swirl can be obtained. In particular, a high swirl can be obtained at a high rotation speed, and a small DI
It is also possible to respond to In addition, since the winding portion 8 and the concave portion 7 of the helical port 2 have a compact configuration that can be accommodated substantially within the range of the port exit width B, it is suitable for the small DI. Furthermore, the use of a normal straight tangential port instead of the irregular tangential port reduces the passage resistance.

By the way, when such a port layout is adopted, the structure around the intake valve of the helical port 2 is shown in FIG.
Something like: In this figure, the flow of the intake air is indicated by arrows.

That is, the valve guide 16 is inserted and fixed to the cylinder head 15, and the valve stem 18 of the intake valve 17 is inserted into the valve guide 16 so as to be able to move up and down. The lower side of the valve guide 16 is held by a valve guide boss 19 projecting into the helical port 2. A sleeve insertion hole 20 is formed vertically adjacent to the helical port 2 with the partition wall 14 interposed therebetween, and an injector sleeve 21 is press-fitted into the sleeve insertion hole 20 from above. In particular, press-fitting is performed at the upper and lower portions of the sleeve insertion hole 20, and a narrow gap 25 is formed at an intermediate portion. An injector (not shown) is inserted into the injector sleeve 21. The injector sleeve 21 is immersed in the water jacket 22 and is water-cooled. 8 is a winding part, 7
Is a recess, 6 is a port outlet, and 23 is a valve seat.

[0024] In this case, an attempt to secure the partition wall 14 having a sufficient thickness t, the passage width B ₈ of the winding unit 8 can not be narrowed will manufacture enough impossible casting. Therefore there is a method of widening the passage width B ₈ is separated position from the helical port 2 of the injector sleeve 21, injector which can not be adopted because it is desirable to place the center of the cylinder.

To solve this problem, the valve guide boss 19 may be removed as shown in FIG. In this way by that amount, it is possible to widen the left of the passage width B ₈ of the valve guide 16 in castable size. At this time, the valve guide 16 is exposed in the helical port 2.
The valve guide boss 19 is removed around the entire periphery of the valve guide 16, and a thin portion is also removed on the right side of the valve guide 16 to form a gap 24. This is to allow the drill blade to escape during drilling of the valve guide hole. Since the gap 24 also forms a part of the winding portion 8, intake air flowing therethrough is generated. In other words, a flow that short-circuits the inside of the valve guide 16 is generated.

However, this structure also has a problem. That is, the gap 25 between the partition wall 14 and the injector sleeve 21 can be obtained.
However, there are problems such as cavitation and crevice corrosion caused by the flow of boiling or heated cooling water.

In order to solve this problem, the valve guide 16 may be further removed at the portion where the valve guide boss 19 is removed as shown in FIG. Then the partition 1
4 can be moved to the intake valve 17 side, and the gap 25 can be enlarged. At this time, the lower end of the valve guide 16 is slightly protruded in the helical port 2, and the valve stem 18 is exposed longer. Thus the left passage area of the valve stem 18, in addition to the passage width B ₈ is enlarged, the right of the gap 24 of the valve stem 18 is also enlarged, the flow of shortcut inside of the valve guide 16 is increased.

When the winding portion 8 is moved toward the valve stem 18 in this manner, the radius of curvature of the winding portion 8 in a plan view state (FIG. 4) is reduced, and there is a concern about the revolvability of the flow in the winding portion 8. However, in the helical port 2, the turning is given even in the concave portion 7 later, so that the turning performance is not substantially reduced. On the contrary, since the flow is given to the concave portion 7 linearly or by shortcut, the flow resistance is reduced.

When the valve guide boss 19 and the valve guide 16 in the helical port 2 are removed as described above, the support rigidity of the intake valve 17 may be reduced. Because there are few thermal problems,
It is sufficient to support the intake valve 17 only with the head portion above the port. Therefore, there is no practical problem due to a decrease in support rigidity. If there is a problem, the support length of the head portion may be increased.

In this way, there is no adverse effect on the intake performance,
It is possible to realize a port layout that enables high swirl without any intake interference in the cylinder. In addition, the use of the straight tangential port 1 can reduce the overall intake resistance, reduce pumping loss, and contribute to improving fuel efficiency. VVT (Variable Valve Timing) that changes the phase of the intake camshaft according to the engine operating condition
) The possibility of adopting a mechanism increases.

As described above, the embodiments of the present invention are not limited to those described above. For example, the helical port on the upstream side in the swirl direction may be a normal helical port as shown in FIG. If there is no problem with the tangential port on the downstream side in the swirl direction, a modified tangential port as shown in FIG. 5E is possible. The number of intake ports is not limited to two.

[0032]

The present invention exhibits the following excellent effects.

(1) Elimination of intake interference in the cylinder,
High swirl can be realized.

(2) The intake resistance can be reduced, the pumping loss can be reduced, and the fuel efficiency can be improved.

(3) Suitable for small DI.

[Brief description of the drawings]

FIG. 1 is a view showing a form of a main part of a multi-valve intake engine according to the present invention, and is a view corresponding to a cross section taken along line AA of FIG.

FIG. 2 is a view showing another embodiment of a main part of the multi-valve intake engine according to the present invention, and is a view corresponding to a cross section taken along line AA of FIG.

FIG. 3 is a diagram illustrating an example of a main part when the port layout of FIG. 4 is adopted, and is a view corresponding to a cross section taken along line AA of FIG. 4;

FIG. 4 is a plan view schematically showing a port layout of the multi-valve intake engine according to the present invention.

FIG. 5 is a plan view schematically showing a port layout of a conventional multi-valve intake engine.

[Explanation of symbols]

1 tangential port 2 helical port 6 outlet 7 recess 8 wound portion 16 valve guide 19 the valve guide boss B port outlet width L _2t linear O ₂ helical port outlet center S swirl direction theta ₂ angle range

Claims (5)

[Claims] 1. A plurality of intake ports are provided for each cylinder, of which a helical port is an upstream intake port in the swirl direction, a tangential port is a downstream intake port, and a valve guide boss in the helical port is removed. A multi-valve intake engine characterized by: 2. The multi-valve intake engine according to claim 1, wherein a valve guide is further removed at a portion where the valve guide boss is removed. 3. The multi-valve intake engine according to claim 1, wherein the tangential port is a straight tangential port. 4. A recess provided in the helical port immediately upstream of the outlet to swell the intake air swollen toward the upstream in the swirl direction and invert the intake air introduced in the swirl direction, and an upstream side of the recess. And a winding portion for turning the swirling direction in the same direction as the swirling direction for the intake air directed to the concave portion, and the concave portion and the winding portion are contained within a range of a substantially port exit width along the swirl tangential direction. The multi-valve intake engine according to claim 1. 5. The swollen portion has a maximum swelling amount on a straight line along a tangential direction of the swirl passing through the center of the port outlet, and the rotation direction is the same as the swirl direction.
The multi-valve intake engine according to any one of claims 1 to 4, wherein the engine has an outlet within an angle range of 0 °.