JP2003074410A - Set of cylinder heads for operating desmodromick valve for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a set of cylinder heads for an internal combustion engine, improved so that an intake duct and an exhaust duct are always positioned at the same position, and an induction system and an exhaust system always have the same connection as to versions of two, three and four valves, in either case of air cooling or liquid cooling. SOLUTION: An intake valve assembly is positioned by making an angle relative to an exhaust valve assembly. The two assemblies severally operate through a locker arm by a single camshaft provided practically along a line running on the center between the two assemblies. The intake duct and the exhaust duct are positioned at the same position in a head in all versions of two, three and four valves, and the induction system and the exhaust system have the same connection.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a set of cylinder heads for an internal combustion engine, the set of cylinder heads being operated by a desmodromic valve, i.e. a valve which positively opens and closes both. The cylinder head for an internal combustion engine according to the invention is particularly applicable to either air-cooled or liquid-cooled, single camshafts and motorcycle engines with two, three or four valves.

The present invention also relates to a motorcycle engine with a set of heads as described herein. The invention also relates in particular to a motorcycle engine which is constructed in a 90-degree V-shape and which has a cylinder with a head according to the invention.

[0003]

U.S. Pat. No. 4,754,728 discloses a four valve cylinder head for a motorcycle engine having a desmodromic valve actuation, a double camshaft, and a liquid cooling system.

Although this type of engine has excellent power characteristics, it is expensive to assemble due to not only the double camshaft but also the desmodromic valve gear.

Furthermore, the engine is not always required to deliver the maximum power possible with respect to its cylinder capacity, so that two or three valve heads, namely:
It is often preferable to use a cylinder head having a single intake valve and a single exhaust valve or two intake valves and a single exhaust valve.

In an air-cooled cylinder head, the use of four valves that are operated in a forced opening / closing manner does not allow proper cooling. Because the size of the passage for the cooling air is small. It is also related to the power that can be delivered by this type of valve timing system and thus to the heat generated by the head. That is, a large area of intake and exhaust port means, which is a four-valve desmodromic engine, can be significantly charged and, as the engine is air cooled, the cylinder head reaches a very high temperature, which Permanent structural deformation and irreversible damage can be introduced to the head.

Thus, the use of four valves for desmodromic operation in an air-cooled engine is not only futile but also dangerous. The power levels that can be achieved by an engine with this type of valve configuration reach temperatures beyond what a typical configuration used for air-cooled engines can support, thus resulting in non-uniform deformation and eventual failure.

With desmodromic valve actuation and air cooling, the cylinder head can have no more than three valves (two intake valves and one exhaust valve). However, the larger cooling capacity of the liquid cooling system provides more space for movement and also improves the power characteristics of an engine with four valves (two intake valves and two exhaust valves).

A liquid cooled version of the cylinder head can also be made from three valves. This is because this configuration also strikes a good compromise between the economy of the configuration and the possibility of engine power generated. The possibility of this generated engine power can be further increased compared to the air-cooled version of the three valve cylinder head,
It approaches the power level that can be obtained by the four valve heads.

[0010]

SUMMARY OF THE INVENTION The present invention is directed to the location of intake and exhaust ducts, and the connection of induction and exhaust systems, whether air cooled or liquid cooled, two, three, and four. The aim is to provide an improved set of cylinder heads for an internal combustion engine, such that they are always the same for one valve version.

[0011]

The cylinder head of the present invention is a set of cylinder heads for operating a desmodromic valve for an internal combustion engine, each head (1) having a shaft (3 '). Applicable to a cylinder (3) having an assembly (4a) of one or two intake valves (4) and an assembly (6a) of one or two exhaust valves (6), so that Two, three,
And forming a set of heads with four valves,
The intake valve assembly (4a) is positioned at an angle with respect to the exhaust valve assembly (6a), and a single camshaft (8) is provided for the two intake and exhaust valve assemblies (4a, 6a). An intake valve (4) provided substantially along a line running in the center between
And each exhaust valve (6) is actuated by a cam (9) for opening a rocker arm (11a, 11).
b, 12a, 12b) and rocker arms (13a, 13a, operated by a cam (10) for opening and closing
13b, 14a, 14b), the intake duct (5) is connected to the intake valve (4), the exhaust duct (7) is connected to the exhaust valve (6), the intake duct (5) and the An exhaust duct (7) is located on the opposite side of the centerline, the intake duct (5) and the exhaust duct (7) each having a connection with an induction and exhaust system, the set of cylinder heads. In all versions with two, three and four valves, said intake duct (5) of each head (1) is positioned at the same position within said head (1) itself and said induction And with the same connection with the exhaust system, said exhaust duct (7) of each head (1)
Are located in the same position in the head (1) itself and have the same connections with the induction and exhaust system,
This achieves the above object.

The intake duct (5) is positioned at an angle (γ) of 35 to 55 degrees with respect to the cylinder shaft (3 ').

The exhaust duct (7) is positioned at an angle (δ) of 80 to 100 degrees with respect to the cylinder axis (3 ').

The intake valve assembly (4a) is positioned at an angle (α) of 10 to 20 degrees with respect to the cylinder axis (3 ').

The exhaust valve assembly (6a) is positioned at an angle (β) of 10 to 20 degrees with respect to the cylinder axis (3 ').

It is characterized in that it includes two intake valves (4) and one exhaust valve (6).

It is characterized in that it comprises two intake valves (4) and two exhaust valves (6).

It is characterized in that it includes one intake valve (4) and one exhaust valve (6).

Includes two spark plugs (16).

The two spark plugs (16) ignite at different moments with a small phase angle with respect to the crank angle, and one and the other of the spark plugs (16) are cyclically alternate front ends. Light up.

The motorcycle engine of the invention comprises a cylinder head (1) forming part of the set of cylinder heads described above.

The motorcycle engine of the present invention includes two cylinders configured in a 90 degree V-shape.

A set of cylinder heads for an internal combustion engine according to the invention can be equipped with two, three or four valves, the engine power and therefore the
The type of cooling the cylinder head heat level (ie,
It can be flexibly adapted to air or liquid).

In particular, the three valve version according to the invention has either air cooling or liquid cooling, optimally between cooling capacity, deliverable power and economy of construction. Come to terms.

One problem in making different versions of cylinder heads having either air cooling or liquid cooling and having two, three, or four valves is that each of the induction and exhaust systems Positioning and positioning of the portion adjacent to the cylinder head itself. This is a particularly important issue for motorcycle engines where the cylinder has a "V" configuration, especially for motorcycle engines whose "V" is 90 degrees. Because these types of engines are relatively large, it is difficult to fit the engine and engine accessories to the motorcycle frame.

Generally, different internal configurations of different head versions result in different positioning of the intake and exhaust ducts,
And requires different connections with each of the induction and exhaust systems. The layout of these systems and the space they occupy therefore need to be modified and adapted as different cylinder head versions are made. This is not always easy
It may not even be possible, with the modification of the parts adjacent to the cylinder head and the connection of the induction and exhaust systems, possibly with the complete redesign of these parts.

The present invention therefore seeks to provide an improved set of cylinder heads for an internal combustion engine, wherein the positions of the intake and exhaust ducts, and
Induction and exhaust system connections, whether air cooled or liquid cooled, are always the same for the two, three, and four valve versions.

This makes it easy to mount the engine on the frame, which means that if the engine type can be changed, the connection with the induction and exhaust system does not have to be changed, which makes the motorcycle more flexible. Be improved. In addition, versions with two, three, or four valves, with either liquid cooling or air cooling, have power levels that require the type of engine needed (more economical engine, or more Engine with output).

[0029]

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a set of cylinder heads for desmodromic valve operation for an internal combustion engine, as set forth in the claims. The dependent claims describe preferred and advantageous embodiments of the invention.

Preferred embodiments of the present invention will now be described with reference to the accompanying drawings, without limiting the scope of the inventive concept.

As mentioned above, with reference to the accompanying drawings, the numeral 1 designates, in its entirety, a cylinder head forming part of a set of heads according to the invention. Head 1
Includes a block 2 forming the combustion chamber of a cylinder 3.
The block 2 includes an intake valve assembly 4a including one or two intake valves 4 each having an intake duct 5.
And an exhaust valve assembly 6a including one or two exhaust valves 6 each having an exhaust duct 7.
If the assembly 4a or 6a has two valves, the valves are parallel to each other.

The intake valve assembly 4a is positioned at an angle α of 10 to 20 degrees with respect to the axis 3'of the cylinder. Similarly, the exhaust valve assembly 6a is positioned at an angle β of 10 to 20 degrees with respect to the cylinder axis 3 ′. Intake and exhaust valve assembly 4 as a whole
a and 6a make an angle that can vary from 20 to 40 degrees with each other. Preferably, the intake and exhaust valve assemblies 4a and 6a each have a 12 with respect to the axis 3'of the cylinder 3.
Positioned at an angle of degrees, thus making an angle of 24 degrees with each other.

These angles depend on the compact combustion chamber,
It allows an optimum compromise between the bending angles of the intake and exhaust ducts in the vicinity of the valve and the dimensions of the system connected to the cylinder head.

The camshaft 8 is used in the valve assembly 4
at least two cams 9a, 9b for opening the intake and exhaust valve assemblies and closing the intake and exhaust valve assemblies 4a, 6a, located substantially along a centerline in a half position between a and 6a. And at least two cams 10a, 10b for

Preferably, each intake valve 4 and exhaust valve 6 has a single rocker arm 11, 12 for opening.
And the single rocker arms 13 and 14 for closing the single actuating cams 9a, 9b, 10a, 10
It is opened and closed by b.

That is, the valve opening cams 9a and 9b and the valve closing cams 10a and 10b respectively actuate one valve 4, 6 via the single rocker arms 11, 12, 13, 14, respectively. This reduces the weight of the reciprocating portion of the valve timing system and thus allows the engine to reach higher rpm.

With the single rocker arm 11, 12 for opening the valve, the centerline positioning of the camshaft 8 further allows the use of the same rocker arm 11, 12. The single rocker arms 13, 14 for closing the valves can also be identical.

Another advantageous characteristic of the valve timing system for obtaining high rpm and low inertia is related to the positioning of the camshaft 8 and the rocker arm locking axis.

The camshaft 8 is positioned in the head 1 with its axis 8'at a height corresponding to the ends of the stems of the valves 4,6. Therefore, the rocker arm 11,
12, 13, 14 can be as short as possible, thus minimizing their weight and moment of inertia.

The rocking arms of the rocker arms 11, 12, 13, 14 are closer to the camshaft 8 than the ends of the stems of the valves 4, 6. Therefore, the lever arms of the rocker arms 11, 12, 13, 14 on the cam side are shorter than the lever arms on the valve side. The ratio of the lever arm on the cam side to the lever arm on the valve side is 0.5.
~ 0.8, preferably 0.8 for rocker arms to open and 0.7 for rocker arms to close.

As a result of the preferred lever arm ratio of the rocker arm, the lift of the valves 4, 6 can be higher than the lift of the corresponding actuating cam, which reduces the valve inertia and the overall size of the cylinder head.

The characteristics of each cylinder head according to the invention will now be described.

1 to 3 show a liquid cooled version of a three valve, showing a passage 15 for the cooling liquid. The intake duct 5 is positioned at an angle γ with respect to the cylinder axis 3 ′, which angle γ is between 35 and 55 degrees, preferably 45 degrees.

The difference between the angle α of the intake valve 4 and the angle γ of the intake duct 5 is 15 to 45 degrees, that is,
Note that the difference is small. This allows a wide angle connection between the intake duct and the valve abutment surface and prevents the valve from obstructing the passage.

The angle of the exhaust duct 7 is larger than the angle of the intake duct. This is because the exhaust gas is subject to a relatively high pressure, so there are less interference problems. Therefore,
The exhaust duct is positioned at an angle δ ranging from 80 to 100 degrees with respect to the cylinder axis 3 ′, the angle δ being preferably 90 degrees.

The angles α, β, γ, δ are the same for all cylinder heads in the set according to the invention, even in the two and four valve versions. Furthermore, as mentioned above, the respective connections with the induction and exhaust systems are also the same for all heads, both in terms of position and shape.

That is, three and four cylinder heads
For the one valve version, the intake duct 5 initially has two valve bearing surfaces and is merged into a single duct, such as a two valve cylinder head with a single valve bearing surface.

The exhaust duct is also merged into a single duct, such as the two and three valve versions, which initially have two valve bearing surfaces in the four valve version and first have a single valve bearing surface. It

The above intake and exhaust duct angles γ and δ are particularly advantageous for a V-shaped cylinder configuration with a guide on the inner surface of the cylinder.

In particular, it is advantageous to position the intake duct at an angle γ equal to half the angle between the cylinders. For example, if the angle between the cylinders is 90 degrees, which is a preferable angle, the angle γ of the intake duct is 45 degrees. This angle γ
The value of is optimally balanced between the need to limit the size of the cylinder head and making the intake duct as vertical as possible.

FIG. 2 is a partial sectional view showing two rocker arms 13a and 13b for closing two intake valves and a rocker arm 14 for closing an exhaust valve. The rocker arms 13a, 13b, 14 for closing the three valves are identical, thus reducing manufacturing and spare parts costs.

FIG. 3 shows two intake valves for opening two intake valves.
It is a partial sectional view showing two rocker arms 11a and 11b and a rocker arm 12 for opening an exhaust valve. Rocker arms 11a, 11 for opening the valve
b and 12 are also identical to each other.

As shown in FIGS. 2 and 3, the camshaft 8 has three cams 10 for closing the valves 4, 6.
a, 10b, 10c and three cams 9a, 9b, 9c for opening the valves 4, 6. That is, each valve operates with a single cam.

FIG. 4 shows an air cooled version of a three valve. This presents air passages that dissipate heat even between the intake and exhaust valves.

FIG. 5 is a front view of the combustion chamber, with some parts cut away, showing the position of the valve and the two spark plugs 16.

As a result of the position of the centerline of the camshaft 8, it is not possible to fit a single spark plug, so that the two sparkplugs 16 also do not interfere with the camshaft 8 so that the centerline is not disturbed. Positioned along and tilted towards the exhaust valve. The spark plug 16 is directed towards the exhaust valve 6 to start combustion first in the hotter part of the combustion chamber, thus eliminating the possibility of knocking. This knocking tends to occur in the hotter parts of the combustion chamber, as is known.

In order to reduce the roughness of the combustion typical of a double ignition system and improve the smoothness of combustion, the two spark plugs 16 have a small phase angle with respect to the crank angle at different instants. Light up. In order to prevent creating hot areas in the cylinder head 2 and the piston crown, one and the other of the spark plugs 16 are ignited alternately in an alternating manner first.

The double ignition system, which has different ignition times for the two spark plugs, also makes the combustion quieter, and experiments have shown that the engine produced in this way produces 3 dB less noise than a simultaneously ignited engine. I understood it.

It should be noted that a single exhaust valve with a single exhaust duct offers two main advantages.

The first advantage is effective cooling, even in air cooled versions. Because the single duct is around and behind the exhaust duct,
This is because the sorting effect by air is reduced.

A second advantage is that the substantially cylindrical single exhaust duct keeps the exhaust gases flowing towards the exhaust system hot. This is because the ratio of the side surface area to the passage cross-sectional area is smaller than the two valve configuration with two exhaust ducts.

Due to the fact that the exhaust gas remains hot while traveling to the exhaust system, the catalytic converter can be warmed faster and begin to process the burned gas faster, thus reducing pollution. It That is, the temperature of the catalytic converter having such a configuration and the single exhaust valve and the single exhaust duct is faster,
Reach its operating temperature.

FIGS. 6-10 show a liquid cooled version of four valves.

In this case, as described above, the configuration in which the liquid is only cooled is selected. This is because effective heat dissipation is possible.

The part of the induction-side combustion chamber with the intake valve and the duct is substantially the same as the three-valve version of the cylinder head.

There are two exhaust valves 6 on the exhaust side,
The exhaust ducts are each merged to form a single duct. Thus, in addition to having the same position and the same exhaust system connections as the other cylinder heads in the set according to the invention (ie cylinder heads with two and three valves), the exhaust gas will have two separate exhaust ducts. It allows it to be maintained at a higher temperature than the version it has. This has the advantage, as mentioned above, of quickly raising the temperature of the catalytic converter to the operating temperature.

FIG. 8 shows the construction of the single rocker arms 13a, 13b, 14a, 14b for closing, which are respectively cams 10a, 10b, 10c, 10d.
, The single valves 4 and 6 are closed.

9 and 10 show two different embodiments of the rocker arm configuration for opening. Figure 9
Single rocker arms 11a, 11b, 1 for opening
2a, 12b, each rocker arm opens a single valve 4, 6 by a cam 9a, 9b, 9c, 9d.

FIG. 10 shows a configuration with two rocker arms 11 and 12, each rocker arm opening two valves 4, 6 simultaneously via cams 9a, 9b respectively.

The second embodiment slightly increases the inertia of the valve timing gear, but makes it possible to reduce the space occupied by the cam for opening.
This is because there are two less cams to open and the camshaft 8 is shorter.

In another embodiment, not shown, the rocker arms 13, 14 for closing the valves are also provided with two valves 4, via cams 10a, 10b, respectively.
Close 6 at the same time. In this embodiment, the camshaft 8 is very similar to the camshaft of the two valve version of the cylinder head shown in FIGS. 13 and 14 and described below.

This four valve version also has a double ignition system to avoid obstruction between the camshaft 8 and the spark plug 16.

11-14 show a two valve, air cooled version of the cylinder head.

In this two-valve version, derived from the three-valve air-cooled version described above, the part of the combustion chamber with the valve 6 and the exhaust duct 7, which is on the exhaust side, is of the cylinder head with three valves. Substantially the same as the corresponding side. 1 on the induction side
There are only one intake valve 4 and one intake duct 5.
In this version as well, the positions and connections for the induction and exhaust systems are the same as for the other cylinder heads (with three and four valves) of the set according to the invention.

As shown in FIGS. 13 and 14, the valves 4 and 6 have single cams 9a, 9b and 10a, respectively.
Rocker arms 11, 12, 1 operated by 10b
It is opened and closed by 3, 14.

In this case, the camshaft 8 has only four cams (two for opening and two for closing) and is therefore relatively short. For this reason, only one spark plug 16 is used, which is located in a substantially central position.

The present invention has important advantages.

As a result of the modular construction, the manufacture of cylinder heads in the set according to the invention is economical. Of course, the parts of the three valve heads on the exhaust side are substantially the same as the corresponding parts of the two valve heads in the set, and the parts on the induction side are the same as the corresponding parts of the four valve heads. Is. The rocker arm that actuates the valve is the same in each of the rocker arm assembly for opening and the rocker arm assembly for closing. In addition, the opening and closing rocker arm has 2
It may be the same for different cylinder head versions with one, three, and four valves.

The rocker arm lever ratio reduces the valve timing gear inertia and overall cylinder head size. The single camshaft design helps reduce head size and manufacturing costs.

Intake and exhaust ducts in the same position,
Having the same connection to the exhaust and induction systems respectively,
The structure of the head according to the invention greatly simplifies the design of these systems and the parts adjacent to the engine,
It is very convenient for V-shaped engines, especially for engines where the V-shaped configuration is 90 degrees. This is because the engine can be easily attached to the frame.

With a single exhaust duct, two and three
The fact of having a single exhaust valve in a two valve version is advantageous for reducing exhaust emissions. This is because the exhaust gas is kept at a higher temperature and thus the temperature of the catalytic converter can reach the operating temperature faster.

With respect to crank angle, the double ignition system, which ignites the spark plug at different moments, runs the engine quieter than an engine with a system that ignites simultaneously.

[0083]

According to the present invention, whether the positions of the intake and exhaust ducts and the connection of the induction and exhaust systems are air-cooled or liquid-cooled, two or three,
An improved set of cylinder heads for an internal combustion engine may be provided, as is always the same for four and four valve versions.

[Brief description of drawings]

FIG. 1 is a cross-sectional side view of a three valve liquid cooled cylinder head forming part of a set of heads according to the present invention.

FIG. 2 shows some parts cut away,
2 is a partial cross-sectional view of the engine cylinder head shown in FIG. 1, showing a rocker arm for closing a valve.

FIG. 3 shows that some parts have been cut away,
FIG. 6 is a partial cross-sectional view of the engine cylinder head shown in the previous figures, showing a rocker arm for opening the valve.

FIG. 4 is a cross-sectional side view of a three valve air cooled cylinder head forming part of a set of heads according to the present invention.

5 is a partial view of a combustion chamber of the cylinder head shown in FIG. 4, showing a configuration of a valve.

FIG. 6 is a cross-sectional side view of a four valve liquid cooling cylinder head forming part of a set of heads according to the present invention.

FIG. 7 is a partial view of a combustion chamber of the cylinder head shown in FIG. 6, showing a configuration of a valve.

FIG. 8 shows that some parts have been cut away,
FIG. 8 is a partial cross-sectional view of the engine cylinder head shown in FIGS. 6 and 7, showing a rocker arm for closing the valve.

FIG. 9 shows that some parts have been cut away,
9 is a partial cross-sectional view of the engine cylinder head shown in FIGS. 6-8, showing a first rocker arm for opening a valve; FIG.
2 shows an embodiment of the present invention.

FIG. 10 is a partial cross-sectional view of the engine cylinder head shown in the previous figures, with some parts cut away, showing a second embodiment of a rocker arm for opening a valve. .

FIG. 11 is a cross-sectional side view of a two valve air cooled cylinder head forming part of a set of heads according to the present invention.

FIG. 12 is a partial view of a combustion chamber of the cylinder head shown in FIG. 11, showing a configuration of a valve.

FIG. 13 is a partial cross-sectional view of the engine cylinder head shown in FIGS. 11 and 12, with some portions cut away, showing a rocker arm for closing the valve.

FIG. 14 is a partial cross-sectional view of the engine cylinder head shown in FIGS. 11-13, with some portions cut away, showing the rocker arm for opening the valve.

[Explanation of symbols]

1 engine cylinder head 2 cylinder head block 3 cylinders 3'cylinder shaft 4 intake valve 4a Intake valve assembly 5 intake duct 6 exhaust valve 6a Exhaust valve assembly 7 exhaust duct 8 camshaft 8'camshaft axis 9a cam 9b cam 9c cam 9d cam 10a cam 10b cam 10c cam 10d cam

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) F01L 1/30 F01L 1/30 F02B 75/22 F02B 75/22 D F02F 1/32 F02F 1/32 1 / 36 1/36 // F02B 75/18 F02B 75/18 L (72) Inventor Mengoli Gianluigi Italy E-40054 Bologna Maddalena di Budurio, Bierse. Donato, 15 / Ar F term (reference) 3G016 AA02 AA07 AA19 BA03 BA06 BA18 BA27 BA39 BA42 BA43 BB25 BB26 CA28 CA46 GA01 3G024 AA04 AA05 AA09 AA11 AA17 AA18 CA05 CA20 DA01 DA03 DA04 DA05 DA06 DA09 DA16 EA04

Claims (12)

[Claims] 1. A set of cylinder heads for operating a desmodromic valve for an internal combustion engine, each head (1) having a shaft (3 ').
Applicable to one or two intake valves (4)
Assembly (4a) and one or two exhaust valves (6) assembly (6a), so that 2
Forming a set of heads having one, three, and four valves, the intake valve assembly (4a) being positioned at an angle with respect to the exhaust valve assembly (6a) and having a single camshaft. (8) is provided substantially along a line running through the center between the two intake and exhaust valve assemblies (4a, 6a), each intake valve (4) and each exhaust valve (6) opening. Rocker arm (11) operated by a cam (9) for
a, 11b, 12a, 12b) and closed by a rocker arm (13a, 13b, 14a, 14b) actuated by a cam (10) for closing, the intake duct (5) to the intake valve (4). Connected, the exhaust duct (7) is connected to the exhaust valve (6), the intake duct (5) and the exhaust duct (7) are
Located on opposite sides of the centerline, the intake duct (5) and the exhaust duct (7) each have a connection with an induction and exhaust system, the set of cylinder heads being two, three , And in all versions with four valves, the intake duct (5) of each head (1) is located in the same position in the head (1) itself and has the same connection with the induction and exhaust system. And the exhaust duct (7) of each head (1) is located at the same position in the head (1) itself and has the same connection with the induction and exhaust system, A set of cylinder heads for operating a desmodromic valve for an internal combustion engine. 2. The internal combustion engine according to claim 1, characterized in that the intake duct (5) is positioned at an angle (γ) of 35 to 55 degrees with respect to the cylinder axis (3 ′). Set of cylinder heads (1) for. 3. Internal combustion according to claim 1 or 2, characterized in that the exhaust duct (7) is positioned at an angle (δ) of 80 to 100 degrees with respect to the cylinder axis (3 ′). A set of cylinder heads (1) for the engine. 4. The intake valve assembly (4a) comprises:
Cylinder head (1) for an internal combustion engine according to any of claims 1 to 3, characterized in that it is positioned at an angle (?) Of 10 to 20 degrees with respect to the cylinder axis (3 '). set. 5. The exhaust valve assembly (6a) comprises:
Cylinder head (1) for an internal combustion engine according to any of claims 1 to 4, characterized in that it is positioned at an angle (?) Of 10 to 20 degrees with respect to the cylinder axis (3 '). set. 6. Cylinder head (1) for an internal combustion engine according to any of claims 1 to 5, characterized in that it comprises two intake valves (4) and one exhaust valve (6). 7. Cylinder head (1) for an internal combustion engine according to any of claims 1 to 5, characterized in that it comprises two intake valves (4) and two exhaust valves (6). 8. Cylinder head (1) for an internal combustion engine according to any of claims 1 to 5, characterized in that it comprises one intake valve (4) and one exhaust valve (6). 9. A set of cylinder heads (1) for an internal combustion engine according to any of claims 1 to 8, characterized in that it comprises two spark plugs (16). 10. The two spark plugs (16)
However, with a small phase angle with respect to the crank angle,
10. Cylinder head (1) for an internal combustion engine according to claim 9, characterized in that it ignites at different moments and one and the other of the spark plugs (16) ignite alternately in a cyclical manner first. set. 11. A motorcycle engine comprising a cylinder head (1) forming part of a set of cylinder heads according to claim 1. 12. The motorcycle engine of claim 11, including two cylinders configured in a 90 degree V-shape.