JPS5925016A - L-head internal combustion engine - Google Patents

Abstract

PURPOSE:To increase the compression ratio of an engine, by installing a piston body on the top surface of a poppet valve. CONSTITUTION:Piston body 30 is installed on a top surface 12a of a valve body 12 of a poppet valve 10 so that the piston body continues to be under a condition to be inserted into a cylinder hole 15 at least until the compression stroke of an engine is completed. This causes a space 23, formed above the top surface of the valve body 12, to be airtightly partitioned from a fuel chamber 7, and thereby a combustion chamber 7 is decreased in an effective capacity after the completion of a compression stroke, resulting in ability to increase the compression ratio of an engine by an amount equivalent to said decreased capacity.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a side valve type in which a poppet valve for controlling opening and closing of a combustion chamber is arranged on the side of a cylinder with the top surface of its valve body facing the bottom surface of the cylinder head. It concerns internal combustion engines.

Conventionally, in this type of side valve type internal combustion engine, the valve lift space of the poppet valves (intake valve and exhaust valve) is secured in the space above the poppet valve that communicates with the combustion chamber in the cylinder.
Therefore, during the compression stroke of the engine, that is, when the poppet valve opens, the volume of the valve lift space formed above the poppet valve becomes part of the combustion chamber, and the effective volume of the combustion chamber at the end of the compression stroke increases accordingly. As a result, it is difficult to increase the reduction ratio of the engine above a certain level, and there is a problem in that various performances such as fuel consumption rate and output of the engine deteriorate accordingly.

The present invention addresses the problems of the conventional side-valve type internal combustion engine as described above, and improves the engine by making it possible to exclude the volume of the valve lift space of the poppet valve from the effective volume of the combustion chamber during the compression stroke. The main objective is to provide a side valve type internal combustion engine that promotes a high compression ratio of the engine and thereby improves the thermal efficiency of the engine. This was done for the other purpose of reducing costs, and in a side-valve type internal combustion engine having the basic configuration as shown in the title, a valve of appropriate size is placed on the lower surface of the cylinder head and facing the valve body of the poppet valve. While forming a cylindrical hole, 12 screws formed separately from the valve body are installed on the top surface of the valve body, and the piston body is inserted into the cylindrical hole at least until the end of the compression stroke of the engine. It is characterized in that it is fitted in the cylindrical hole airtightly and slidably so that the state in which it is fitted can be maintained.

Hereinafter, the side valve type internal combustion engine of the present invention will be explained based on the embodiment shown in FIGS. 1 to 3. FIG. The combustion chamber part of a side-valve type diesel engine using structural members is shown, and the symbol / in the figure is a cylinder block,
Cylinder 13 is the cylinder head, Y is the piston, J is the crankshaft, O is the camshaft, 7 is the combustion chamber, Z is the intake passage,
10 is a poppet valve (intake valve). In addition, fuel injection valve,
Illustrations of the exhaust passage and exhaust valve are omitted.

The poppet 10 includes a thin plate-shaped valve body /2 and a straight rod-shaped valve stem /3
It has a valve body/,! The valve seat 7 is attached to the valve seat 7 formed at the mouth end of the intake passage on the combustion chamber 7 side with the top surface /2α facing upward. On the top surface /2α of the valve body /2, a disc-shaped piston body 30 is formed separately from the valve body /2 with a minute gap △5 and is relatively rotatable by the mounting bolt 3 /. It is attached so that it can be relatively displaced slightly in the radial direction. This piston body 30 is arranged in the cylinder head 3 so as to face the valve body /2 of the poppet valve 10.
It is slidably and airtightly fitted into a cylindrical hole /j formed on the lower surface 3α of the cylindrical hole /j. The inner diameter of the cylindrical hole /3 is set to be larger than the outer diameter d of the valve body /2 by an appropriate amount. This is so that the valve body /2 can be fitted into the cylindrical hole /S even if the mounting position of the cylinder block / and cylinder head 3 is slightly shifted in the horizontal direction, and also to make it possible to fit the valve body /2 into the cylindrical hole /S. Valve body/
This is to enable an intake passage to be formed around the valve body /4 even when the valve body /4 is fitted.

In addition, the most suitable size ratio between the two is D/d=/, about 2◇ Also, since the valve body/2 of the poppet valve 10 and the piston body 30 are constructed as separate bodies, there is no need for the valve seat. In contrast, the piston body 30, which is repeatedly seated and constantly exposed to high-temperature combustion gas (particularly in the case of an exhaust valve) and under relatively favorable conditions compared to the valve body 2, is lighter. Furthermore, it can be formed from inexpensive materials. In the illustrated embodiment, the seal ring 23 is attached to the piston body 30 so that the seal ring 2j and the inner peripheral surface of the cylindrical hole /j are brought into sliding contact, but if this seal ring 2j is removed and the piston In the case where the body 30 and the inner circumferential surface of the cylindrical hole /j are brought into direct metal contact, a material with good lubricity may be particularly selected as the material for the piston body 30.

j- On the other hand, the piston body lift space 23 formed on the upper surface 30α side of the piston body 30 in the cylindrical hole IS is communicated with the outside through a through hole /7 formed in the cylinder Rad 3, Furthermore, if necessary, it can be communicated with an appropriate oil source such as a breather chamber. Therefore, no back pressure is exerted within the piston body lift space 23 due to the upward movement of the piston body 30, so that the intake valve 10 can be operated more smoothly.

As mentioned above, the top surface of the valve body /2 of the poppet valve 10 / , 2
(LJJIC Piston body 30 formed separately from the valve body
cylindrical hole lj at least until the end of the engine's compression stroke.
When the piston body 3 is installed so that it remains fitted in the valve body 2, the piston body 3 formed on the top surface 2α of the valve body 2
0, that is, the lift space 23 of the valve body/2 is airtightly divided from the combustion chamber 7, so that at the end of the compression stroke of the engine, the intake passage is opened from the top surface 41a side of the bistonk. The volume obtained by subtracting the volume of the axially projected portion of the valve body/2 of the poppet valve 10 from the total volume of the series of combustion chambers 7 leading to the valve seat on the g side is -the effective volume of the combustion chamber 7 at the end of the compression stroke. It becomes the volume.

Therefore, the poppet valve 10. Compared to the case where a valve stroke space communicating with the combustion chamber in the cylinder is formed on the top surface/2rL of the valve body/2, the combustion chamber 7 at the end of the compression stroke is
The effective volume of the engine is reduced, and the compression ratio of the engine is increased accordingly, making it possible to obtain a compression ratio suitable for a diesel engine (approximately 7 g or more).

In addition, in this practical example, the valve body /2 and the piston body 30
Since the mounting bolt 3/ is mounted so that it can be relatively rotated and relatively displaced slightly in the radial direction, it is much more convenient than when both are integrally formed as in another embodiment (Fig. 3), which will be described later. This improves the mechanical properties of the valve body even if the axis of the intake valve 10 and the axis of the cylindrical hole /j on the cylinder head 3 side are slightly misaligned in the horizontal direction.
, 2 can be accurately seated on the valve seat, thereby improving the seating performance of the poppet valve 10.

Furthermore, in the embodiment shown in FIG. 1, the valve body /2 and the piston body 30
are arranged at a distance, it is possible to suppress heat transfer from the piston body 30 side to the valve body/2 side as much as possible, and it is relatively preferable compared to the valve body/2 which is seated on the valve seat. Under these conditions, the piston body 30 can be made of a material that is lighter and cheaper than the valve body /2, thereby promoting weight reduction and cost reduction.

Note that the reference numeral 2j in FIG. 1 is a seal ring.

3 and 3 show an intake valve section of a side valve type internal combustion engine according to another embodiment of the present invention. In the suction valve section shown in FIG. 2, a piston body 30 is mounted on the top surface /2α of the valve body /2 of the poppet valve 10 in direct contact with a fixed pole 3.2.

By doing this, it is possible to obtain almost the same effect as in the embodiment shown in FIG. can further increase the compression ratio. In this case, since the outer diameters of the valve body /2 and the piston body 30 are approximately the same, a cutout part 3 is formed at the mouth end of the cylindrical hole /j on the side opposite to the piston. This cutout portion 31 ensures an intake passage area around the valve body /2 when the poppet valve 10 is opened.

Further, the poppet 10 shown in FIG. 3 is installed with the piston body 3θ in direct contact with the valve body /2, as in the case of the poppet valve shown in FIG. 2, or the piston 30 is fitted at the same time. The inner diameter of the cylindrical hole /j is made larger than the outer diameter d of the valve body /2 as in the embodiment shown in FIG. This ensures a sufficient intake passage area.

Next, to explain the present invention in detail, in the side valve type internal combustion engine of the present invention, the piston body attached to the valve body of the poppet valve is fitted into a cylindrical hole formed on the lower surface of the cylinder head. Since the lift volume can be excluded from the combustion chamber volume at the end of the compression stroke,
The effective volume of the combustion chamber at the end of the compression stroke is smaller than in a conventional side-valve type internal combustion engine in which the valve lift volume of the poppet valve is part of the combustion chamber volume at the end of the compression stroke. The effect is that it is possible to increase the compression ratio of the engine to obtain the compression ratio required for a diesel engine, and to improve the engine performance such as fuel consumption rate and output. There is.

In addition, since the poppet valve's valve body and the piston body fitted into the cylindrical hole are separate structures, the screws and torsion body can be used separately from the poppet valve, which is made of relatively expensive high-grade steel, depending on its usage conditions. Accordingly, it can be formed from a cheaper and lighter material, which has the effect of promoting weight reduction and cost reduction of the poppet valve portion.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view of a main part of a side valve type internal combustion engine according to an embodiment of the present invention, and FIGS. ...... Cylinder α ... Cylinder top surface 3 @... Cylinder head 3a --- Bottom surface of cylinder head ... Piston 10 - Ri ...... Top surface of piston 10...Bottom valve/2...Valve body/2α...Top surface of valve body/j---Cylindrical hole 30------ -Piston body applicant Yanmar Diesel Co., Ltd.-//- JIJ Figure 3 121-

Claims (1)

[Claims] t A poppet valve (10) for opening and closing the combustion chamber (7) is installed on the side of the cylinder (2) on the top surface (/2) of its valve body (/2).
A side valve type internal combustion engine is provided, in which a side valve type internal combustion engine is provided, in which a side valve (2G) is disposed facing a lower surface (3G) of the cylinder head (3), and the poppet valve (2G) is disposed opposite the lower surface (3G) of the cylinder head (3). A cylindrical hole (/j) of an appropriate size is formed at a position facing the valve body (/2) of 10), while a cylindrical hole (/j) of an appropriate size is formed on the top surface (/2G) of the valve body (/2). Attach the piston body (30) formed separately from 2), and keep the piston body (30) in the cylindrical hole -(/3) until the end of the engine's compression stroke at least until the cylindrical body (/j). 1. A side valve type internal combustion engine, characterized in that the internal combustion engine is fitted in an airtight and slidable manner so as to maintain a state in which the engine is fitted.