JP2683388B2 - 4-cycle engine intake system - Google Patents

Description

TECHNICAL FIELD The present invention relates to an intake system for a four-cycle engine having three or more intake valves per cylinder.

[Prior Art] Conventionally, there is known a multi-valve engine in which three or more intake valves are provided for each cylinder, in which one of the intake valves is provided near the center of the cylinder bore. In this engine, in order to increase the amount of intake air to the intake valve near the center of the bore, the intake passage leading to the intake valve near the center of the bore is changed to another one as shown in, for example, "JP-A-58-47109". Is provided independently of the intake passage communicating with the intake valve.

[Problems to be Solved by the Invention] However, in the case of this prior art, since the intake passage connected to the intake valve near the center of the bore is guided to the head cover side as it is, the intake passage accommodates the camshaft and the valve lifter. It will penetrate through the valve chamber. Then, especially in an engine with a large number of valves, the valve mechanism such as the cam shaft and the valve lifter is densely arranged in the limited space portion of the valve chamber, so that the valve mechanism and the intake passage may not interfere with each other. It becomes a problem.

Therefore, if the shape and arrangement of the intake passage are prioritized, it will be a great obstacle in determining the layout of the intake valve and the lift amount, and the arrangement interval of the cam shafts will have to be widened, leading to an increase in the size of the cylinder head. There are problems such as.

The present invention has been made based on such a situation, and the intake passages connected to the intake valves near the center of the bore can be arranged without interfering with the valve mechanism, and moreover, a large passage area of each intake passage can be secured. Another object of the present invention is to provide an intake system for a four-cycle engine that can increase the intake rate by making the intake passage itself from the vicinity of the center of the bore smooth with less bending.

[Means for Solving the Problems] Therefore, in the present invention, three or more intake valves are provided per cylinder, and one of these intake valves is arranged near the center of the bore of the cylinder, and these intake valves are provided. Assuming a 4-cycle engine in which a valve is opened and closed by a valve operating mechanism such as a cam shaft provided on the cylinder head, an intake passage communicating with other intake valves except the intake valve near the center of the bore is provided on one side of the cylinder head. It is characterized in that, while being opened, another intake passage independently connected to the intake valve near the center of the bore is opened on the other side surface of the cylinder head which is adjacent to the one side surface and extends in a direction intersecting with the one side surface.

[Operation] According to this configuration, since the independent intake passage connected to the intake valve near the center of the bore is opened to the side surface of the cylinder head like the other intake passages, this independent intake passage is provided on the valve mechanism side. Therefore, it is possible to prevent the interference with the valve mechanism.

Moreover, in this case, the independent intake passage is not one side surface of the cylinder head where the other intake passage opens,
Since the other side surface adjacent to this one side surface is opened, even if the number of intake passages is large, there is no fear that the space on the side of the cylinder head where these intake passages are opened will be insufficient, and the passage area of each intake passage will be sufficient. Can be secured. At the same time, if the intake passage connected to the intake valve near the center of the bore is independently opened on the other side surface of the cylinder head, the intake passage can be compared with the case where the intake passage is branched from the other intake passage in the cylinder head. You can shorten the length of the passage,
It can also be easily routed, and the intake passage itself can be made smooth with few bends to enhance the intake efficiency.

[Embodiment] A first embodiment of the present invention will be described below with reference to FIGS. 1 to 9 applied to a 4-cycle single cylinder engine.

In FIG. 9, reference numeral 1 is a crankcase, 2 is a cylinder block, 3 is a cylinder head, 4 is a head cover,
The cylinder head 3 is vertically divided into a head body 3a and a cam case 3b. On the lower surface of the head body 3a, a recess 5 is formed corresponding to the cylinder 2a in the cylinder block 2, and the recess 5 forms a combustion chamber 7 with the piston 6.

Then, as schematically shown in FIG. 8, the recess 5 is provided with four intake ports 8a, 8b, 8c, 8d and two exhaust ports 9a, 9b. These intake ports 8a, 8b, 8c, 8d and exhaust ports 9a, 9b
It is provided so as to sandwich an axis A ₁ that passes through the bore center X ₁ of the cylinder 2a and extends in the axial direction of the crankshaft 1a. Intake ports 8a, 8b,
8c, among 8d, one of the intake port 8a is provided on the bore center X _1, the other remaining inlet 8b, 8c, 8d in one side of the axis A _1, the periphery of the inlet port 8a Are located in That is, the inlet port 8a, 8b, 8c, 8d are provided at diagonal positions of the substantially rhombic, with the intake port 8b and 8d located on the axis A ₁ and parallel to the axis A _2, the inlet port 8a 8c intake port on the axis a ₂
8b and 8d are arranged so as to sandwich them from the orthogonal direction. The exhaust port 9a, 9b is positioned on the other side of the axis A _1, it is juxtaposed along the axial direction of the axis A _1.

The intake ports 8a, 8b, 8c, 8d arranged in this way are opened and closed by the four intake valves 10a, 10b, 10c, 10d, and the exhaust ports 9a, 9b are also opened by the two exhaust valves 11a, 11b. It is opened and closed. The valve stems 12 of the intake valves 10a, 10b, 10c, 10d and the exhaust valves 11a, 11b are supported by the head main body 3a, and the distal ends thereof are led out into the cam case 3b. In the case of this embodiment, other intake valve 10 with the exception of the intake valve 10a for opening and closing an intake port 8a on the bore center X ₁
The b, 10c, 10d and the exhaust valves 11a, 11b are arranged radially with respect to the bore center X ₁ , and the valve stem 12 thereof is inclined in a direction away from the axis A _{1 as} it advances toward the cam case 3b. . At this time, the intake valve on the bore center X ₁
The intake valves 10b, 10c, 10d other than 10a are arranged side by side along the circumferential direction of the cylinder 2a, and the inclination angle of the intake valve 10c at the center of the intake valves 10b, 10c, 10d on both sides is as shown in FIG. ,Ten
It is set smaller than the inclination angle of d. Therefore, the tip ends of the valve stems 12 of these three intake valves 10b, 10c, 10d are positioned on the same straight line that is parallel to the axis A ₁ .

The valve stem 12 of the intake valve 10a located on the bore center X ₁ is arranged in a posture standing upright along the axial direction of the substantially cylinder 2a, each such valve 10a, 10b, 10c, 10
Due to the arrangement of d, 11a and 11b, the inner surface of the recess 5 is formed in a smooth hemisphere.

Note that the concave portion 5 as shown in FIG. 8, are located on opposite sides of the inlet 8a of the bore center X _1, a pair of spark plugs 13 are mounted.

A valve operating chamber 14 is formed between the cam case 3b and the head cover 4. In the valve operating chamber 14, the intake valve 10a,
Two intake camshafts 15a, 15b for opening and closing 10b, 10c, 10d
And a single exhaust camshaft 16 for opening and closing the exhaust valves 11a and 11b. These three cam shafts 15a, 15b,
16 are parallel to each other along the axial direction of the crankshaft 1a, and have a plurality of bearing portions 17 protruding from the upper surface of the cam case 3b.
And a cam cap 18, which is bolted to the bearing portion 17, are rotatably supported. One intake camshaft 15
a is for opening and closing the other intake valves 10b, 10c, 10d other than the intake valve 10a located on the bore center X _1, on the extension line of the valve stem 12 of these intake valves 10b, 10c, 10d, that is, It is located on one side of the axis A ₁ . Then, three intake cams 19 are provided on the outer periphery of the intake camshaft 15a.
b, 19c, 19d are projected, and these intake cams 19b, 19c, 1
9d is in sliding contact with the valve stem 12 of the intake valves 10b, 10c, 10d via the valve lifter 20.

The other intake camshaft 15b is for opening and closing a single intake valve 10a located on the bore center X ₁ , and is located on an extension of the valve stem 12 of this intake valve 10a. Therefore, the local intake camshaft 15b is displaced in the direction of the bore center X ₁ from the one intake camshaft 15a, and the single intake cam 21 protruding on the outer periphery of the intake camshaft 15a is inserted through the valve lifter 22 into the intake valve. It is in sliding contact with the valve stem 12 of 10a.

Further, the exhaust cam shaft 16 is located on the extension line of the valve stem 12 of the exhaust valves 11a, 11b, that is, on the other side of the axis A ₁ , and the exhaust cam 23 projecting on the outer periphery of the exhaust cam shaft 16 has an exhaust valve 11a. , 11b are in sliding contact with the valve stem 12 via a valve lifter 24. Therefore, in the case of the present embodiment, the three cam shafts 15a, 15b, 16 and the valve lifters 20, 22, 24 constitute a valve operating mechanism, but rocker arms are used instead of the valve lifters 20, 22, 24. You may use.

 Note that reference numeral 25 in the drawing denotes a valve spring.

Of the three cam shafts 15a, 15b, 16 in the valve operating chamber 14, one of the intake cam shafts 15a and the exhaust cam shaft 16 located on both sides is
The timing gears 26 and 27 mesh with each other, and the timing gear 26 on the exhaust camshaft 16 side meshes with the crank gear 30 of the crankshaft 1a via a pair of middle gears 28 and 29. The exhaust cam shaft 16 and the local intake cam shaft 15b are also interlocked with each other via other timing gears 31 and 32 that mesh with each other. Therefore, both of the two intake cam shafts 15a and 15b are rotationally driven in the same direction at the same speed by the power transmission from the exhaust cam shaft 16.

In the case of this embodiment, the intake cams 19b, 19c, 19d and 21 open and close the four intake valves 10a, 10b, 10c, 10d at the same timing, so that they extend in the same direction as shown in FIG. and out, an intake cam 21 of which opening and closing the intake valve 10a on the bore center X _1, intake cam 19c for opening and closing the intake valve 10c is in a positional relationship facing each other in a direction perpendicular to both the cam shafts 15a, 15b and It is provided. Moreover, the two intake cam shafts 15a and 15b are connected to each other by the two intake cams 19 facing each other.
Rotation loci R ₁ and R ₂ of the tips of c and 21 are arranged at positions where they overlap in the axial direction of the cam shafts 15a and 15b.

By the way, inside the head body 3a, the intake ports 8a, 8
Four intake passages 35a, 35b, 35c, 35d connected individually to b, 8c, 8d
And two exhaust passages 36a, 36b that are connected to the exhaust ports 9a, 9b are formed. Of these intake passages 35a, 35b, 35c, 35d,
The other intake passages 35b, 35c, 35d except the intake passage 35a connected to the intake port 8a on the bore center X ₁ and the exhaust passages 36a, 36b are
As shown in FIG. 4 and FIG. 4, the head main body 3a passes through below the valve operating chamber 14 accommodating the intake camshaft 15a, the exhaust camshaft 16 and the valve lifters 23, 24, which are led out in opposite directions. There are three side-by-side openings. Then, adjacent to one side surface where these intake passages 35b, 35c, 35d open,
And on the other side surface of the head body 3a extending in the intersecting direction,
An intake passage 35a that communicates with the intake port 8a of the bore center X ₁ is independently opened.

That is, the intake passage 35a is once drawn out upward as shown in FIG. 2, and then, in order to avoid the valve lifter 22 and the valve spring 25, other intake passages 35b, 35c, 35d are formed inside the head body 3a. It is bent laterally along the intersecting direction, passes below the valve operating chamber 14, and is opened on the other side surface of the head body 3a. Therefore, all of the intake passages 35a, 35b, 35c, 35d and the exhaust passages 36a, 36b are connected to the valve operating chamber 14
This means that the side surface of the cylinder head 3 is opened without penetrating the inside.

A common intake pipe 37 is connected to the open ends of the intake passages 35b, 35c, 35d, and an intake pipe 38 is also connected to the open end of a single independent intake passage 35a. The intake pipes 37 and 38 are provided with fuel injection valves (not shown).

With this configuration, the intake port 8a near the bore center X ₁
Since the intake passage 35a that communicates with the above is opened to the side surface of the head body 3a through the lower side of the valve operating chamber 14, the intake passage 35a
a does not penetrate into the valve operating chamber 14 and these camshafts 15
It is possible to prevent interference with valve operating mechanisms such as a, 15b, 16 and valve lifters 20, 22, 24.

Moreover, since the intake passage 35a connected to the intake port 8 does not open on one side surface of the head body 3a where the other intake passages 35b, 35c, 35d open, but on the other side surface adjacent to this one side surface independently. , The intake passage 35 per cylinder as in this embodiment.
Even if the number of a, 35b, 35c, 35d is as large as four, there is no shortage of the space on the side surface of the head body 3a where these intake passages 35a, 35b, 35c, 35d open, and each intake aisle
It is possible to secure a sufficiently large passage area for 35a, 35b, 35c, 35d.

Further, if the intake passage 35a is independently opened on the other side surface of the head body 3a, compared to the case where the intake passage 35a is branched from the other intake passages 35b, 35c, 35d in the head body 3a,
It is possible to reduce the length of the intake passage 35a and to make the passage itself smooth with few bends. Because
Intake flow resistance is reduced, and intake passages 35a, 35b, 35c, 35d
In combination with being able to secure a sufficient passage area, the suction efficiency is improved.

In the first embodiment, the intake port near the bore center X ₁
Intake passages 35b, 35c, 35d other than the intake passage 35a connected to 8a
Are independently opened on one side surface of the head main body 3a. For example, as shown by an imaginary line in FIG. 7, the intake passage 35b,
The upstream ends of the 35c and 35d may be merged, and the single merged portion 41 having the elongated hole shape may be opened to one side surface of the head body 3a.

On the other hand, FIG. 10 and FIG. 11 show a cylinder head 3 equipped with the four intake valves 10a, 10b, 10c, 10d and the two exhaust valves 11a, 11b as described above as a V-shape for a motorcycle. A second embodiment is shown when applied to a two cylinder engine.

That is, in FIG. 10, reference numeral 51 is a frame, and the V-shaped two-cylinder engine 52 is mounted on the frame 51. On the crankcase 53 of this engine 52,
The front cylinder 54 and the rear cylinder 55 are V
It stands in shape. These cylinders 54, 55 are common to the front and rear, and the cylinder block 2 and the cylinder head 3 thereof are in the front and rear opposite directions. Because of this, the front cylinder
Of the intake passages 35a, 35b, 35c, 35d of the rear cylinder 55 and the rear cylinder 55, the other intake passages, 35b, 35c, 35d except the intake passage 35a from the bore center X ₁ are provided on the opposing surfaces of these cylinders 54, 55. It is opened, and the remaining independent intake passage 35a is
The front cylinder 54 and the rear cylinder 55 are opened on the opposite side surfaces, respectively.

Since the pistons 6 of the cylinders 54 and 55 are connected to the single common crankshaft 1a, the front cylinder
54 and the rear cylinder 55, as shown in FIG.
It is offset in the axial direction of 1a. Therefore, one side of each cylinder 54, 55 has a cylinder 54, 55 facing the front and rear.
A step portion 56 is formed between and, and the intake pipe 38 is located in the step portion 56.

The intake pipes 37 and 38 are guided right above the engine 52,
It is connected to an air cleaner 58 provided at the bottom of the fuel tank 57.

According to the second embodiment as described above, the intake pipe 38 located on the side of the cylinder head 3 is accommodated in the step portion 56 formed on the side of each cylinder 54, 55.
Can be accommodated within the width L of the front and rear cylinders 54, 55,
The intake pipe 38 does not largely protrude to the side of the engine 52.

Further, FIG. 12 shows a third embodiment of the present invention. In the third embodiment, the intake passages 35a of the front and rear cylinders 54, 55 are arranged on the same side of the cylinder head 3, and the intake pipes 38 are arranged centrally on one side of the engine 52.

According to the third embodiment, since the protruding positions of the intake pipe 38 are concentrated on one side of the engine 52, the intake pipe 38 is neatly arranged, which is advantageous in terms of appearance and the intake system of the engine 52. Can be easily assembled.

Furthermore, FIGS. 13 and 14 show a fourth embodiment of the present invention.

In this fourth embodiment, three intake ports 60a per cylinder,
An engine with 60b, 60c is shown, one of these inlets 60a, 60b, 60c is located on the bore center X ₁ and each inlet 60a, 60b, 60c is The intake valves 10a, 10b, 10c are individually opened and closed. Other intake valves 10b, 10c except intake valve 10a on bore center X ₁
Is the two intake cams 6 provided on one intake camshaft 15a.
The intake valve 60a on the bore center X ₁ is opened and closed individually by the 1a and 61b, and is opened and closed by a single intake cam 62 provided on the other intake cam shaft 15b. And
As shown in FIG. 13, the three intake cams 61a, 61b, and 62 are provided on both intake camshafts 15 when the cylinder head 3 is viewed in plan.
The intake cams 62, which are arranged in a zigzag pattern along the axial direction of a and 15b and open and close the intake valve 60a on the bore center X ₁ , enter between the other two adjacent intake cams 61a and 61b. There is. For this reason, the rotation loci R ₁ , R _{2 of} the intake cams 61a, 61b and 62 are
When the intake camshafts 15a, 15b are viewed from the axial direction, the camshafts 15a, 15b overlap in the axial direction by a distance l.

In the present embodiment, one intake camshaft 15
The timing gear 31 is fixed to a, and the power is transmitted from the intake camshaft 51a to the other intake camshaft 15b.
Is driven to rotate. Therefore, two intake camshafts 15
The a and 15b are rotationally driven in opposite directions.

In each of the above-mentioned embodiments, the driving means for the cam shaft is not limited to the gear, but may be a chain or a toothed belt.

[Effect of the Invention] According to the present invention described in detail above, it is possible to prevent interference between the intake passage connected to the intake valve near the center of the bore and the valve operating mechanism, and this intake passage is a cylinder head in which another intake passage opens. Since it does not open on one side surface but on the other side surface adjacent to this one side surface, there is no shortage of the space on the side surface of the cylinder head where these intake passages open, and the passage area of each intake passage is enlarged accordingly. can do. At the same time, if the intake passage from the center of the bore is opened independently, the intake passage can be routed more easily than when the intake passage is branched from the other intake passage in the cylinder head. The length of the passage can be shortened, and the passage itself can be made smooth with little bending. Therefore, the flow resistance of the intake air is reduced and the passage area of the intake passage can be secured, and the intake air amount can be increased, which contributes to the improvement of the engine output.

[Brief description of the drawings]

1 to 9 show a first embodiment of the present invention.
FIG. 2 is a plan view of the head body, FIG. 2 is a sectional view taken along the line II-II in FIG. 1, FIG. 3 is a perspective view of the intake passage, and FIG.
5 is a sectional view taken along line IV-IV in FIG. 5, FIG. 5 is a plan view of the cylinder head, FIG. 6 is a sectional view taken along line VI-VI in FIG. 5, and FIG.
FIG. 8 is a side view of the cylinder head, FIG. 8 is a schematic view showing the arrangement state of the intake valve and the exhaust valve, FIG. 9 is a side view in which the drive path of the camshaft is partially sectioned, and FIGS. 10 and 11 are FIG. 10 shows a second embodiment of the present invention, FIG. 10 is a side view of a motorcycle, and FIG. 11 is a plan view of a cylinder head of a V-type engine.
FIG. 12 is a plan view around a cylinder head showing a third embodiment of the present invention, FIGS. 13 and 14 show a fourth embodiment of the present invention, and FIG. 13 is a plan view of the cylinder head. The figure is a schematic diagram showing the arrangement of intake valves and exhaust valves. 2a ... cylinder, 3 ... cylinder head, 10a, 10b, 10c, 10d
...... Intake valve, 15a, 15b ...... Intake cam shaft, 16 ...... Exhaust cam shaft, 35a, 35b, 35c, 35d ...... Intake passage.

Claims (1)

(57) [Claims] 1. A cylinder having three or more intake valves,
In a four-cycle engine in which one of these intake valves is arranged near the center of the bore of the cylinder, and these intake valves are opened and closed by a valve mechanism such as a cam shaft provided in the cylinder head, The intake passage that connects to the other intake valves except the valve is opened on one side surface of the cylinder head, and the other side surface of the cylinder head that extends in the direction intersecting with the one side surface is connected to the intake valve near the bore center. An intake device for a four-cycle engine, which is characterized by opening another intake passage that continues independently.