JPH01253504A - Four-cycle engine - Google Patents

Abstract

PURPOSE:To secure sufficient intake valve area while decreasing a combustion period in an engine provided with at least three intake valves per cylinder by specifying positional relations including inclination between each intake valve and discharge valve. CONSTITUTION:In three intake valves 5 which open/close an intake passage 1, the intermediate intake valve 5 faces a combustion chamber 3 with a smaller inclination to an axis l1 of a cylinder (a) than those of a discharge valves 6. Both side discharge valves 6 are provided to cross a center line l3 which passes the center of combustion chamber 3 and is parallel to a plurality of camshafts 9, 10. A wall surface 17 which faces inside the cylinder (a) and has a larger inclination to the axis l1 thereof than that of a lower end face 5a of the intermediate intake valve 5 is formed on a lower surface of a cylinder head (b) and outside the intermediate intake valve 5. Both side intake valves 5 face the combustion chamber 3 with a larger inclination to the axis l1 of the cylinder (a) than that of the intermediate intake valve 5.

Description

[Detailed description of the invention] The present invention relates to a four-stroke engine.

Conventionally, in order to improve output performance in a high-speed operating range in a four-stroke engine, three intake valves have been provided per cylinder.

(For example, British Patent No. 296125) However, when so many valves are provided, a problem arises as to how the many valves should face the combustion chamber.

In other words, as in British Patent No. 296125, the area occupied by the valve in the combustion chamber, that is, the valve area, is increased. l) A problem arises in that combustion becomes slow.

For this reason, it is conceivable to make the combustion chamber more compact and shorten the combustion period by reducing the inclination of the intake valve, but simply reducing the inclination of the valve makes it difficult to secure a sufficient intake valve area.

The present invention has been made in view of the above circumstances, and its purpose is to shorten the combustion period while ensuring a sufficient intake valve area in an engine provided with at least three intake valves. Our goal is to provide a 4-cycle ennon that can be used.

An example of implementing the present invention will be explained with reference to the drawings.
One cylinder of a cycle engine is shown. In the figure, (a) is the cylinder, (b) is the throat to the cylinder, (1) is the intake passage, and (2) is the cylinder.
) is the exhaust passage.

(3) is a combustion chamber formed on the lower surface of the cylinder head (b), and an intake passage (1) and an exhaust passage (2) are open therein. (17) is the intermediate intake valve (5), which will be described later.
There are 11 prongs located on the outside of the cylinder head (l) and formed on the lower surface of the cylinder head (l). This wall surface (17) is a cylinder (
a) Lower end surface (5a) of the intake valve facing inside and in the middle
The cylinder (a) is formed so that its slope toward the axis #Q (Ql) is thicker than that of the cylinder (a). That is, the axis (C+>
Let the slope of the wall (17) be (α,), and the cylinder ([
If the slope of l) with respect to the axis (0, 1) is (a,), then α, α.

In this case, it is assumed that the inclination with respect to the axis is measured on the combustion chamber (3) side, as shown in FIG.

(4) is a hole for installing a spark plug, and it opens at the center of the upper surface of the serious combustion chamber (3).

(5) is an intake valve that opens the intake passage (1);
6) is an exhaust valve that opens and closes the exhaust passage (2).

The lower ends of these intake valves (5) and exhaust valves (6) face the combustion chamber (3) and correspond to the opening ends of the intake passages (1) and exhaust passages (2), respectively, and the middle portions of the intake valves (5) and exhaust valves (6) face the combustion chamber (3). )
(6b) is slidably supported on the wall surface of the cylinder head (b).

(708) is a cam that is connected to the upper end of both valves (5H6), and both valves (5) and (6) are connected to the corresponding cam directly above it via the 7-tar ()) and (8). Axis (9
) (lO), and is driven by the shafts (9) and (10).

(11) and (12) are the intake valve (5) and the exhaust valve (
6) is a spring that biases the valve in the valve closing direction.

On the other hand, the camshafts (9) and (10) are connected to the cylinder head (b
) is rotatably held via a cam carrier (13) and cam caps (14) and (15).

(]6) is a cover that covers the camshafts (9) and (10) and cam caps (14) and (15), and the cam carrier (
13) are connected in two layers.

However, in order to improve the output performance of the above-mentioned 4-stroke engine, the intake valve (5) and exhaust valve (5) per cylinder are
Although the number of f-lubes (6) is plural, at least three intake valves (5) are provided.

In addition, depending on the number of each valve <5) <6), the intake passage (1)
Of course, the number of exhaust passages (2) is also increased.

The arrangement structure of the three intake valves (5) is such that the middle intake valve (5) faces the combustion chamber (3) with a smaller inclination with respect to the cylinder axis (Ql) than the exhaust valve (6). . In addition, the intake valves (5) on both sides are tilted more toward the axis (Q+) than the one in the middle, so that the combustion chamber (
3).

That is, the inclination angle of the intermediate intake valve (5) is (αI),
If the inclination angle of the intake valves (5) on both sides is (α2), and the inclination angle of the exhaust valve (6) is (αyu), then α1 × α
2 hsα1kua.

Further, each of the intake valves (5) is arranged so that its axis (Q2) passes through the axis (0,) of the camshaft (9).

In addition, the intake valves on both sides are arranged so as to intersect with a center line (Q,) that passes through the center of the combustion chamber (3) and is flat on the camshafts (9) and (10).

According to this embodiment configured as described above, on the lower surface of the cylinder head (b) on the outside of the intermediate intake valve (5),
The lower end surface of the middle intake valve (5a) facing into the cylinder (a)
) is formed so that the wall surface (17) has a larger inclination with respect to the axis (Ql) of the cylinder (a), so that squish is likely to occur between the wall surface (17) and the top surface of the piston.

Furthermore, since the inclination of the intermediate intake valve (5) with respect to the axis CQl) of the cylinder (a) is made smaller than that of the exhaust valve (6), the piston top surface and the intermediate intake valve (5)
The distance from the surroundings becomes narrower, and it is emitted from the wall surface (17).
- The squish remains at a high speed in the combustion chamber (3)
Since it is transmitted to the center side of the squish, the combustion period is shortened together with the squish emission/L.

Moreover, at this time, the intake valves (5) on both sides are aligned with the center line (Q).
Intake valve (5)
can be brought closer to the exhaust valve (6) as a whole, making it easy to form a wide wall surface (17) on the lower surface of the cylinder head (b) outside the intermediate intake valve (5).

Furthermore, the intake valves (5) on both sides are connected to the middle intake valve (5).
) The inclination of the cylinder (a) with respect to the axis (Ql) is larger than that of the cylinder (a) so that it faces the combustion chamber (3), so the inclination of the intermediate intake valve (5) is reduced to ensure that the squish is transmitted effectively. Nevertheless, a wide surface area for arranging the intake valves (5) on both sides can be secured, and a sufficient intake valve area can be secured.

On the other hand, the intake valves (5) are arranged such that the middle intake valve (5) is offset outward from the center line (O3) as shown in FIG. do not interfere with each other.

In addition, since each intake valve (5) has its axis (Ql) passing through the axis (O3) of the camshaft (9), it is possible to use a valve other than the 7ter (7) as a means to connect the intake valve (5) to the axis (O3) of the camshaft (9). There is no need for a new one.

On the other hand, two exhaust valves (6) are provided, and the combustion chamber (3)
It is arranged on a straight line (O4) parallel to the center line (Q,) within the center line.

In addition, the exhaust valve (6) has its 4Q (QS>) passing through the axis (0,) of the camshaft (10), and the inclination angle (α,) with respect to the axis (Q, ) of the cylinder (a) is equal. It is set.

Since there are two exhaust valves, they can be arranged in series within the combustion chamber (3) without interfering with each other, and they can also be used as a means for connecting them to the camshaft (]O0.
There is no need for anything other than the tar (8).

In the above embodiment, only three intake valves (5) were provided, but three exhaust valves (6) can be provided if the same arrangement as the intake valve (5) is adopted.

As described above, in providing three intake valves, the present invention makes the inclination of the intermediate intake valve with respect to the axis of the cylinder smaller than that of the exhaust valve, so that the lower surface of the cylinder head on the outside of the intermediate intake valve faces into the cylinder. Since we formed a wall surface that has a larger inclination to the cylinder axis than the lower end surface of the intake valve, squishes are more likely to occur between the wall surface and the top surface of the piston, and the gaps between the squishes and the top surface of the piston are narrower. The combustion period is shortened because it passes between the intake valve and the intermediate intake valve and is transmitted to the center of the combustion chamber while maintaining a high velocity.

However, because the intake valves on both sides are arranged so that they intersect with the center line that passes through the center of the combustion chamber and is parallel to the camshaft, the intake valves as a whole can be moved toward the exhaust valve side, and the intake valves in the middle It is easier to form a wide wall surface on the lower surface of the cylinder head on the outside of the valve, which is more advantageous in shortening the fuel period.

In addition, the intake valves on both sides were tilted more toward the cylinder axis than the middle intake valve so that they faced the combustion chamber, so even though the middle intake valve was made to have a smaller tilt to effectively transmit the squish. First, a wide surface area for arranging the intake valves on both sides can be secured, and a sufficient intake valve area can be secured.

Therefore, the intended purpose can be achieved.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal sectional view showing the ennon of the present invention, and Fig. 2 is a longitudinal sectional view showing the ennon of the present invention.
3 is a sectional view taken along the line (II)-(It) in the figure, FIG. 3 is a sectional view taken along the line (I[l)-(III) in FIG.
It is a sectional view taken along the line (IV)-(■) in the figure. In the figure, (a) - cylinder (b) - cylinder head (1
) - Intake passage (2) - Exhaust passage (3) - Combustion chamber (5) - Intake valve (5a) - Lower end surface of middle intake valve (6) - Exhaust valve (9) (10) - Camshaft (1
7) - Wall surface (Ql) - Cylinder axis (O
2) - Axis of the intake valve (Q,) - Center line of the combustion chamber (Q,) - Axis of the exhaust valve (0,) (02) - Axis of the camshaft (O1) - Inclination angle of the intermediate intake valve (O2) - Inclination angle of intake valves on both sides (α,) - Inclination angle of exhaust valve (α,) - Inclination angle of lower end of middle intake valve (a,) -
Wall slope angle Patent applicant: Yamaha Motor Co., Ltd. Figure ■Figure 2

Claims (1)

[Claims] In a four-stroke engine with at least three intake valves per cylinder, the middle intake valve faces the combustion chamber at a smaller angle to the cylinder axis than the exhaust valve, while passing through the center of the combustion chamber to the camshaft. The intake valves on both sides are arranged so as to intersect the parallel center line, and a wall surface facing into the cylinder is formed on the lower surface of the cylinder head on the outside of the intermediate intake valve, and has a greater inclination with respect to the cylinder axis than the lower end surface of the intermediate intake valve. At the same time, the intake valves on both sides face the combustion chamber at a greater inclination to the cylinder axis than the intake valve in the middle.