JPH0430322Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Field of Industrial Application) The present invention relates to an improvement of an intake and exhaust valve device for an internal combustion engine.

(Prior Art) A rotary valve is known as an intake and exhaust valve for a four-stroke internal combustion engine.

This is equipped with a rotary valve that rotates around an axis perpendicular to the intake and exhaust ports of the cylinder head.
Intake and exhaust are performed by rotating a rotary valve in synchronization with engine rotation.

Although this rotary valve has various advantages over ordinary reciprocating poppet valves, such as no opening/closing noise, good high-speed follow-up, and simplified structure,
Because the rotating parts are exposed to high-temperature combustion gases, they are prone to deformation and wear, resulting in problems such as poor sealing against high-pressure gas and malfunctions due to rotational friction, making them difficult to put into practical use. Nakatsuta.

(Problem that the invention aims to solve) However, recent internal combustion engines for automobiles tend to become faster and more powerful, and improvements in intake and exhaust valves are strongly needed in order to increase intake and exhaust efficiency. It was wanted.

In this respect, the rotary valve will be able to fully satisfy the above requirements if the above-mentioned problems such as sealability are solved.

The present invention focuses on these points and aims to provide an intake/exhaust valve device that makes it possible to realize high speed and high output internal combustion engines by eliminating the drawbacks of the rotary valves described above.

(Means for Solving the Problems) The present invention provides an internal combustion engine in which an intake/exhaust port is formed in a cylinder head, and an intake/exhaust valve for opening and closing the intake/exhaust port is constituted by a rotary valve. Intake and exhaust cylindrical holes for freely rotating the cylinder head are provided in parallel in the cylinder head, the intake and exhaust ports are formed to cross a part of the cylindrical holes, and each intake and exhaust rotary valve is made of ceramics. At the same time, each rotary valve is provided with a notch that communicates the port with the engine combustion chamber for a predetermined period corresponding to the intake stroke or the exhaust stroke, and a passage that guides cooling oil along the rotation axis, and Valve driving means for driving the valve in synchronization with engine crankshaft rotation;
The notch is configured to be driven in the direction of closing the valve while rotating toward the combustion chamber from a position where the port communicates with the combustion chamber.

(Function) The rotary valve made of ceramics exhibits high heat resistance against high temperatures from the combustion chamber, and at the same time, it guides cooling oil into the passage that passes through the shaft center, thereby avoiding localized high temperatures of the rotary valve. The amount of thermal deformation of the rotary valve is extremely small. Therefore, even if the operating conditions change, the sealing performance against gas pressure does not change, and the rotary operating characteristics can be stably maintained.

In addition, each rotary valve for intake and exhaust is closed by rotating the notch in the direction facing the combustion chamber from the state where the port is open, so between the start of the combustion stroke and the end of the exhaust stroke, the intake rotary valve Combustion gas does not enter the notch, and even after the exhaust stroke ends and the port is closed, the notch temporarily faces the combustion chamber and combustion gas does not enter the exhaust side rotary valve. The residual gas in the chamber is taken into the notch and carried away before the combustion stroke begins. As a result,
Gas exchange is ensured and stable combustion performance is achieved.

(Example) An example of the present invention will be described below based on FIGS. 1 to 4.

In FIG. 1, 1 is a cylinder head, 2 is a cylinder block, and 3 is a piston.

An intake port 4 and an exhaust port 5 are formed in the cylinder head 1 and communicate with a combustion chamber 6. An intake side rotary valve 7 and an exhaust side rotary valve 8 are provided in parallel so as to be perpendicular to the intake port 4 and the exhaust port 5, respectively. An ignition plug 9 is installed between these rotary valves 7 and 8.

As shown in FIGS. 2 and 3, the rotary valves 7 and 8
cylindrical holes 10 and 11 are formed in the cylinder head 1 in a state that partially communicates with the combustion chamber 6 in order to accommodate the intake and exhaust ports 4, A cylindrical seal metal 12 is disposed except for a portion 5, and the rotary valves 7 and 8 are supported in sliding contact therewithin. Note that a side seal metal 13 for sealing the end faces of the rotary valves 7 and 8 is disposed perpendicular to the rotation axis.

The rotary valves 7 and 8 are connected to the seal metals 12 and 13.
It is composed of a cylindrical valve part 14 that is in contact with the cylindrical valve part 14, and a shaft part 15 that is integrally fitted to the axis of the valve part 14, and the valve part 14 is made of highly heat-resistant ceramics.
The shaft portion 15 is formed of metal so as to maintain a predetermined mechanical strength, and a passage 16 for guiding cooling oil is formed through the center thereof, through which a portion of the engine lubricating oil is circulated.

Although not shown, a cooling jacket is formed on the cylinder head 1 to circulate cooling water, thereby promoting heat dissipation from the intake and exhaust valves 7 and 8 from the head side.

As shown in FIG. 4, a notch 18 as a valve hole is formed in the valve portion 14 at a position corresponding to the intake port 4 and the exhaust port 5.
The combustion chamber 6 and the intake/exhaust ports 4, 5 are communicated through the combustion chamber 6 and the intake/exhaust ports 4, 5, respectively.

In addition, the bottom sides of the intake and exhaust ports 4 and 5 connected to the combustion chamber 6 are provided with overlapping parts over a predetermined rotation angle with the valve portions 14 of the rotary valves 7 and 8, respectively, in order to ensure gas sealing during the combustion stroke. Seat part 20
is formed.

The rotary valves 7 and 8 open the intake and exhaust ports 4 and 5 during the intake stroke and exhaust stroke of the engine, respectively, during one rotation.
The rotation angle range of the notch 18 in the circumferential direction is determined in order to minimize the loss caused by guiding the intake air flow or the exhaust air flow at an acute angle, and also to communicate with the combustion chamber 6. Because of the overlap between the valve and The thickness of the portion 14 is set so as to obtain a predetermined intake and exhaust efficiency.

Further, the axial width W of the notch 18 is made to correspond to the inner diameter of the cylinder, and the seal width Ws of the valve portion 14 is appropriately set in consideration of gas sealing properties.

The valve part 14, including the notch part 18, is integrally molded by lowering a ceramic mold, so even if it has a complicated shape, it can be manufactured easily.

These rotary valves 7 and 8 have their respective notches 18
so that after opening the intake port 4 or exhaust port 5, the valve closes while rotating in the direction of the combustion chamber 6.
In other words, in the figure, the rotary valve 7 on the intake side rotates counterclockwise, and the rotary valve 8 on the exhaust side rotates clockwise, and in the case of a four-stroke cycle internal combustion engine, one rotation for every two rotations of the crankshaft. The valve is rotated by a valve driving means such as a chain or belt (not shown) so as to be rotated.

Note that if the rotational phase of the rotary valves 7 and 8, for example, the winding angle of the timing belt, can be changed by an idler pulley, intake and exhaust timing can be obtained in accordance with the operating state.

The system is constructed as described above, and its operation will be explained next.

The state shown in FIG. 1 shows just before the start of the intake stroke, and as the intake side rotary valve 7 rotates counterclockwise in the figure, the notch 18 opens the intake port 4.
The combustion chamber 6 starts communicating with the piston 3, and the air-fuel mixture (air) is sucked into the cylinder as the piston 3 descends.

By the time the piston 3 reaches the bottom dead center, the rotational rear end of the notch 18 reaches the seal 20 and communication between the intake port 4 and the combustion chamber 6 is cut off.

After that, the piston 3 enters the upward stroke, but at this point the exhaust side rotary valve 8, which rotates clockwise,
The notch 18 is closed by the seal metal 12 in the cylinder head 1, and as the rotation of the rotary valve 7 progresses, the amount of overlap with the seal part 20 increases, so as the piston 3 rises, the piston 3 is compressed. Gas is completely sealed.

Ignition is performed by the spark plug 9 near the top dead center of the piston 3, the combustion stroke begins, and when the piston 3 eventually descends to near the bottom dead center, the notch 18 of the exhaust side rotary valve 8 connects the combustion chamber 6 and the exhaust gas. Port 5 begins to communicate, and combustion gas is discharged to exhaust port 5.

The notch 18 of the rotary valve 8 communicates the exhaust port 5 with the combustion chamber 6 during the exhaust stroke when the piston 3 finishes rising, and then closes at the time of transition to the aforementioned intake stroke.

In addition, since the notch 18 temporarily faces the combustion chamber 6 immediately after the exhaust stroke ends and the exhaust port 5 is closed, the combustion gas remaining in the combustion chamber 6 is captured by the notch 18 during this time. As the rotary valve 8 rotates, the gas is discharged from the port 5 just before entering the next exhaust stroke. This is substantially the same effect as lengthening the exhaust stroke, and residual gas can be removed more reliably.

On the other hand, focusing on the rotary valve 7 on the intake side, although its notch 18 temporarily faces the combustion chamber 6 after the intake stroke ends (immediately after the intake port 4 is closed),
By the time the combustion stroke is started, it has rotated to the area of the cylindrical surface of the cylindrical hole 10 and is cut off from the combustion chamber 6. Therefore, combustion gas does not enter the notch 18 of the intake side rotary valve 7, and good intake efficiency can be obtained. If the rotation direction of the rotary valve 7 is reversed (clockwise in the figure), it is possible to perform the suction action, but in this case, the notch 1
8 will open the port 4 while retaining the gas immediately after the exhaust stroke, resulting in deterioration of suction efficiency and the possibility of backfire.

It goes without saying that gas exchange efficiency is improved and stable combustion performance is exhibited by removing exhaust residual gas and improving intake efficiency as described above.

By the way, cooling oil is introduced into the passage 16 of the shaft portion 15 of the rotary valves 7, 8, and in order to actively promote heat exchange from inside, the rotary valves 7, 8 are directly exposed to the combustion gas. The rotary valves 7 and 8 do not become locally hot, and since the outer valve part 14 in particular is made of ceramics with excellent heat resistance, the rotary valves 7 and 8 are almost free from thermal deformation regardless of the operating condition. It never happens.

Therefore, the seal gap between the seal metal 12 that is in sliding contact with the outer periphery of the rotary valves 7 and 8 does not partially change and cause unbalanced contact, or conversely, the contact pressure does not become excessively high, and the sealing gap is always stable. Seal performance can be maintained.

This is further facilitated by the fact that when the rotary valves 7, 8 are closed, there is sufficient overlap, including the seat portion 20.

The valve parts 14 of the rotary valves 7 and 8 are formed of ceramics with minute irregularities on the surface, and as carbon generated during combustion adheres to these minute irregularities, the seal metal 12 on the outer periphery of the valve parts 14 It also ensures lubricity and improves airtightness.

As a result, it is possible to make the seal gap as small as possible without impeding the rotational operation of the rotary valves 7 and 8, which is fully satisfactory from a practical point of view in maintaining gas pressure during the combustion stroke. It was found that the following results were obtained.

The intake and exhaust efficiency is proportional to the area of the notch 18 of the rotary valves 7 and 8, but this depends on the outer diameter and axial length of the valve part 14, and by increasing the outer diameter, it can be improved by increasing the outer diameter and the cylinder inner diameter. In this regard, it is possible to increase the effective area by increasing the axial length, so it is not possible to complicate the valve train system, such as in an engine with 4 valves per cylinder, as is often done recently. It is possible to expand the valve area without having to do so.

By applying the present invention to an oversquare short stroke type engine, it becomes easier to increase the intake and exhaust efficiency by increasing the valve area. Further, since the rotary valves 7 and 8 are arranged in parallel in this way, and the flow of intake air and exhaust air is a through flow, a smooth flow is ensured, which, together with the above, contributes to improving the intake and exhaust efficiency.

(Effects of the invention) As described above, according to the invention, the rotary valve made of ceramics exhibits high heat resistance against high temperatures from the combustion chamber, and at the same time, cooling oil is introduced into the passage passing through the shaft center. This prevents high heat from accumulating in the rotary valve and avoids localized high temperatures.As a result, the amount of thermal deformation of the rotary valve is extremely small, so even if the operating conditions change, the gas pressure remains constant. It always exhibits good sealing performance and maintains stable rotational operating characteristics.

In addition, in the present invention, the valve driving means is configured so that the notch portion of each intake/exhaust rotary valve closes each port while rotating toward the combustion chamber, thereby directing combustion gas to the notch portion of the intake side rotary valve. The gas exchange efficiency of the engine is improved by preventing the infiltration of residual gas and eliminating residual gas through the notch of the exhaust side rotary valve, thereby achieving the effect of achieving stable combustion performance.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of the present invention, FIG. 2 is a perspective explanatory view of a cylinder block centered on a rotary valve, FIG. 3 is a perspective explanatory view of a cylinder block centered on a rotary valve seal metal, FIG. 4 is a perspective view of the rotary valve. 1...Cylinder block, 2...Cylinder, 4
...Intake port, 5...Exhaust port, 6...Combustion chamber, 7...Intake side rotary valve, 8...Exhaust side rotary valve,
DESCRIPTION OF SYMBOLS 10, 11... Cylindrical hole, 12, 13... Seal metal, 14... Valve part, 15... Shaft part, 16... Passage, 18... Notch part, 20... Seat part.

Claims (1)

[Scope of utility model registration request] In an internal combustion engine in which an intake/exhaust port is formed in a cylinder head, and an intake/exhaust valve for opening/closing the intake/exhaust port is constituted by a rotary valve, a cylindrical hole for intake/exhaust that rotatably accommodates the rotary valve is provided. The intake and exhaust ports are provided in parallel to the cylinder head, and the intake and exhaust ports are formed to cross a part of the cylindrical hole, and each rotary valve for intake and exhaust is formed of ceramics, and each rotary valve has an intake stroke or an exhaust stroke. A valve drive for driving each rotary valve in synchronization with the rotation of the engine crankshaft, the valve drive having a notch that communicates the port with the engine combustion chamber for a predetermined period corresponding to An intake/exhaust valve device for an internal combustion engine, characterized in that the means is configured to be driven in a direction to close the valve while rotating toward the combustion chamber from a position where the notch communicates the port and the combustion chamber.