JPH0110409Y2 - - Google Patents

Description

[Detailed explanation of the idea] The present invention relates to an internal combustion engine with a prechamber.

BACKGROUND ART It is essential for an internal combustion engine, especially an internal combustion engine for a vehicle, to be able to provide stable rotation over a wide range from a low speed rotation range to a high speed rotation range. However, since the compression ratio is generally set to obtain a certain level of output in the medium and high speed range, the compression ratio is too high in the low speed range, resulting in the knocking phenomenon. This makes it difficult for the engine to rotate smoothly, resulting in increased vehicle body vibration and engine noise.
It may cause discomfort to passengers. Furthermore, when the compression ratio is set to smooth engine rotation in the low speed rotation range, the compression ratio in the middle and high speed rotation ranges is too small, and as a result, sufficient output cannot be obtained.

Therefore, in recent years, an auxiliary chamber of a predetermined volume is connected to the cylinder through a small hole, and a part of the compressed gas in the combustion chamber is released into this auxiliary chamber during compression, resulting in the same effect as expanding the volume of the compression chamber. This substantially reduces the compression ratio in the low-speed rotation range, and in the high-speed rotation range, the compressed gas flowing into the pre-chamber decreases due to an increase in the low resistance of the compressed gas passing through the small holes, which reduces engine rotation. As the number increases, the compression ratio approaches the original setting, and the compression ratio is varied continuously and smoothly within a certain range, making engine rotation smooth in the low speed range and increasing engine output in the medium and high speed ranges. An engine has been proposed that prevents a decrease in .

However, in engines equipped with the above-mentioned sub-chamber, the bottom surface of the sub-chamber is generally flat, so lubricating oil, fuel oil, etc. tend to accumulate in the sub-chamber.
In such a case, generation of white smoke and unstable rotation may occur.

Furthermore, the engine body and subchamber are formed separately, which reduces the workability of assembling the engine in order to obtain a subchamber with a volume corresponding to the size (displacement) of the engine to which it is applied. or invite
Since a separate member is attached around the cylinder, especially when a larger auxiliary chamber is required, problems such as a large amount of protrusion to the outside of the engine arise in order to secure a predetermined volume.

The present invention has been made in view of the above points, and includes a small hole opened at a predetermined position of the cylinder bore of the engine excluding the cam chain chamber side, and a sub-hole having a predetermined volume that is communicated and connected to the cylinder through the small hole. a sub-chamber for introducing a portion of the compressed gas into the chamber to reduce the compression ratio in a low-speed rotation range; the sub-chamber has an upper box portion integrally formed with the cylinder head; Further, the lower box portion having an opening that faces and abuts the opening of the upper box portion is formed integrally with the cylinder block, and the bottom surface of the lower box portion having a split configuration is formed as an inclined surface. The lowest part of the inclined surface is configured to communicate with the small hole opened in the cylinder bore, which improves the workability of assembling the engine, and at the same time facilitates the cleaning of the inside of the pre-chamber. The volume of the subchamber can be set and the desired volume can be easily secured, without considering the interference of , during engine operation, even if the pre-chamber has a large volume,
To enable the compression ratio to be automatically and effectively varied according to the engine speed without the explosion pressure directly entering the subchamber, and to prevent lubricating oil, fuel oil, etc. from accumulating in the subchamber. An object of the present invention is to provide an internal combustion engine having a pre-chamber with a pre-chamber.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a vertical sectional view of essential parts of an internal combustion engine equipped with a pre-chamber according to the present invention, in which an engine body 1 has a cylinder block 2, a cylinder head 3, and a crank chamber 4, which are connected through gaskets 5 and 6 to a through bolt 7. It is made up of joined parts. A cylinder liner 8a is fitted into the inner hole of the cylinder block 2, and the inner surface forms a cylinder bore 8. A piston 9 that reciprocates within the cylinder bore 8 is fitted into the cylinder bore 8 while being kept airtight by a piston ring 9a. A spark plug 10 is attached to the cylinder head 3, and its tip faces a combustion chamber 11 at the top of the cylinder bore 8. Cooling fins 2a are provided on the outer surfaces of the cylinder block 2 and cylinder head 3.
3a is formed, and on the side of the engine body 1,
A cam chain chamber 12 of a cam chain 12a that interlocks the rotation of a crankshaft (not shown) connected to a connecting rod 9b of a piston 9 with a valve mechanism (not shown).
is formed.

The auxiliary chamber 13 according to the present invention is divided into an upper auxiliary chamber 13a on the cylinder head 3 side and a lower auxiliary chamber 13b on the cylinder block 2 side, and is formed by integral casting with the cylinder head 3 and cylinder block 2, respectively. Ru. The bottom of the lower subchamber 13b is formed into an inclined surface 13c as shown in FIG. On the other hand, a small hole 14 having a predetermined diameter is opened at a predetermined position near the upper portion of the cylinder bore 8. As shown in FIG. 1, the small hole 14 is opened at a position excluding the cam chain chamber 12 side, is approximately horizontal or slightly inclined toward the cylinder bore 8 side, penetrates the cylinder liner 8a and the cylinder side wall, and is located on the side surface of the cylinder block 2. The opening is closed with a plug 16 and communicated with the sub chamber 13 by connecting with a vertical small hole 15 bored at the lowest part of the lower sub chamber 13b and the lower inclined surface 13c formed in the cylinder block 2. Ru. In this way, the small hole communicating between the predetermined position of the cylinder bore 8 and the auxiliary chamber 13 is formed into a substantially horizontal small hole 14 and a vertical small hole 15.
The reason why this is formed is for convenience of processing, and a single inclined hole may be directly bored at a predetermined position of the cylinder bore 8 from the lowest part of the lower inclined surface 13c of the auxiliary chamber 13.

In the above structure, the gasket 5 is connected to the upper end surface of the cylinder block 2, and the cylinder head 3 is connected to the upper end surface of the cylinder block 2 through the gasket 5.
The sealing material 17a is fitted into the sealing groove 17 provided at the lower edge of the upper sub-chamber 13a integrally molded with the cylinder block 2, and the cylinder head 3 is passed through the cylinder block 2.
At the same time as the engine body 1 is assembled,
An airtight subchamber 13 having a predetermined volume and communicating with each other through small holes 14 and 15 having a predetermined opening is formed at a predetermined position of the cylinder bore 8 .

In such an internal combustion engine, when the engine is in a low speed rotation range, the movement speed of the piston 9 is slow, so the influence of the fluid resistance of the small holes 14 and 15 that communicate the predetermined position of the cylinder bore 8 and the auxiliary chamber 13 is small, and the cylinder bore The gas in the cylinder bore 8 flows out into the auxiliary chamber 13 through the small holes 14 and 15 as the piston 9 moves, and easily returns from the auxiliary chamber 13 into the cylinder bore 8, which means that the volume of the cylinder bore 8 has increased. The high compression ratio unique to the engine is substantially reduced to a low compression ratio. As the engine speed increases and the movement speed of the piston 9 becomes faster, the small hole 1
4 and 15 becomes large, it flows out from the cylinder bore 8 to the auxiliary chamber 13, and the auxiliary chamber 13
The delay in the gas returning from the cylinder bore 8 to the cylinder bore 8 increases, resulting in a state in which the gas appears to be trapped in the subchamber 13. Therefore, the function of the auxiliary chamber 13 gradually decreases in proportion to the engine speed, and in the high speed range, the compression ratio almost returns to the high compression ratio unique to the engine.

As a result of the above-mentioned effects, engine startability is improved, similar to conventional engines equipped with a pre-chamber, and knocking and associated vibration and noise can be prevented when the engine is idling or running at low speeds. can.

Moreover, in the internal combustion engine configured as described above, when changing the compression ratio, it can be varied automatically and effectively, and if the rotational speed increases, even if there is a pre-chamber 13 of the required capacity, Sufficient output similar to that without such an auxiliary chamber can be obtained. That is, when an explosion is caused by the spark plug 10 in the combustion chamber 11, if the explosion pressure directly enters the pre-chamber, the explosive force will constantly decrease, leading to a decrease in output.This tendency is particularly strong in cases where the pre-chamber volume is large. However, in the configuration described above, the pre-chamber 13 does not directly communicate with the combustion chamber 11, and therefore, the necessary volume can be secured for the pre-chamber, and the explosion pressure does not directly enter the combustion chamber 11. On the other hand, even in the low speed rotation range, there is no reduction in output due to the above-mentioned reasons.
During the compression stroke, the auxiliary chamber 13 continues to have the above-mentioned introduction effect, so that the predetermined capacity of the auxiliary chamber 13 can be fully utilized to exhibit the compression ratio reduction function during compression.

Furthermore, the internal combustion engine includes a cylinder block 2
If the cylinder head 3 is attached to the engine 1, a pre-chamber 13 of a predetermined volume is formed at the same time as the engine 1 is assembled, while if the cylinder head is removed, the pre-chamber can be washed, and the interior can be easily cleaned. Moreover, the small hole is opened at a position excluding the cam chain chamber 12 side of the engine 1, and the sub-chamber 13 is divided into an upper sub-chamber on the cylinder head side and a lower sub-chamber on the cylinder block side. In other words, the auxiliary chamber 13 is divided into an upper box part and a lower box part, each having a predetermined volume, and the volume is shared between them to form one auxiliary chamber 13 with a predetermined volume. Therefore, the volume of the auxiliary chamber can be determined without considering the interference of the cam drive member passing through the cam chain chamber 12, and even if a large volume is required depending on the displacement of the cylinder of the engine to which it is applied. Even if the sub-chamber 13 is large, it can be easily accommodated, and even if an inclined surface is provided at the bottom of the sub-chamber 13 for discharging lubricating oil etc., the volume of the sub-chamber can be easily secured. be.

As described above, according to the present invention, a small hole is opened at a predetermined position other than the cam chain chamber side of the cylinder bore of an engine, and an auxiliary chamber has a predetermined volume and is connected to the cylinder through the small hole. and a sub-chamber for introducing a part of the compressed gas into the chamber to reduce the compression ratio in the low-speed rotation range, and the sub-chamber has an upper box part integrally formed with the cylinder head, and The cylinder block is configured by integrally forming a lower box part having an opening that faces and comes into contact with the opening of the upper box part, and the bottom surface of the lower box part having a split configuration is an inclined surface,
Since the lowest part of the inclined surface communicates with the small hole opened in the cylinder bore, it is possible to improve the workability of assembling the engine, and by removing the cylinder head, the inside of the pre-chamber can be cleaned. In particular, the volume is shared between the upper and lower box parts, and the volume of the sub-chamber can be determined without considering the interference of the drive member passing through the cam chain chamber, and the size of the sub-chamber is required to be increased depending on the engine to which it is applied. The pre-chamber can be enlarged according to the cylinder displacement, making it easy to secure a predetermined volume, and the compression ratio can be automatically and effectively varied according to the engine speed. In addition, by making the bottom of the subchamber an inclined surface and communicating the bottom of this inclined surface with a small hole opened in the cylinder bore, lubricating oil and fuel oil accumulated in the subchamber can be transferred to the cylinder through the small hole. This has the effect that the normal function of the subchamber is not impaired, and the volume of the subchamber can be easily secured even if such an inclined surface is provided.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is a vertical sectional view of a main part, and FIG. 2 is a sectional view taken along the line A--A in FIG. DESCRIPTION OF SYMBOLS 1...Engine body, 2...Cylinder block, 3...Cylinder head, 8...Cylinder bore, 9...Piston, 13...Subchamber, 13a...
Upper sub-chamber, 13b...lower sub-chamber, 13c...slope surface.

Claims (1)

[Scope of utility model registration request] A sub-chamber having a small hole opened at a predetermined position other than the cam chain chamber side of the cylinder bore of the engine, and a predetermined volume connected to the cylinder via the small hole, and a part of the compressed gas is introduced into the chamber. It has an auxiliary chamber that is introduced to reduce the compression ratio in the low speed rotation range, and the auxiliary chamber has an upper box part formed integrally with the cylinder head and an opening that faces and abuts against the opening of the upper box part. It is constructed by integrally forming a lower box part with a cylinder block, and the bottom face of the lower box part having a split structure is an inclined surface, and an opening is formed between the lowest part of the inclined surface and the cylinder bore. An internal combustion engine equipped with a pre-chamber characterized by communication with a small hole.