JPH04298612A - Valve system of internal combustion engine - Google Patents

Abstract

PURPOSE:To reduce the whole weight and inertia mass uniformly on the suction valve side and on the exhaust valve side when a suction valve and an exhaust valve are opened or closed via locker arms which have different length. CONSTITUTION:A suction valve 3 and an exhaust valve 4 which are provided in a cylinder head 2 are opened or closed via locker arms 5, 6 of pivot type which have a support point 16 on the same side as the cylinder head 2. The suction valve 3 which is further from the support point 16 is made smaller than the exhaust valve 4 which is closer to the support point 16. Consequently, it becomes possible to reduce the whole weight and inertia mass down to equal value on the suction valve side and on the exhaust valve side, and it becomes possible to increase time number of bounce revolutions in the same way.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention provides suction and
This invention relates to a valve train system for an internal combustion engine that has an exhaust valve.

0002

[Prior Art] The valve train of recent automobile engines includes:
Many cylinder heads are constructed so that the intake valve and exhaust valve provided in the cylinder head are driven to open and close via pivot-type rocker arms. According to such a valve train system, valve clearance can be automatically adjusted. Furthermore, since the rocker shaft is not required, it is convenient for making the rocker arm and cylinder head more compact. The rocker arms are formed to have the same length and the same size, and when the intake and exhaust valves are arranged side by side on one side of the cylinder head, they are arranged on the same side of the cylinder head. has been done. When intake and exhaust valves are arranged on both sides of the cylinder head, they are arranged on each valve side.

[0003] Furthermore, as prior art to the present invention, for example,
As shown in Japanese Utility Model Publication No. 51-22165, there is also a structure in which the intake and exhaust valves located on both sides of the cylinder head are driven to open and close from the same side via rocker arms of different lengths. be. Each rocker arm is carried by a separate rocker shaft and is driven by a push rod located on one side of the cylinder head.

0004

However, in the prior art, it is difficult to make the rocker arm compact, and the rocker arm is larger than the pivot type. In particular, the longer rocker arm is heavier, so
When the inertial mass increases during operation, followability tends to decrease,
There is a relatively high possibility that jumps will occur in the high speed rotation range. Therefore, it is difficult to increase the bounce rotational speed of the entire valve train and the allowable rotational speed of the engine, and it is difficult to achieve high output.

[0005] In order to deal with this problem, it is possible to replace the rocker arm with a pivot type rocker arm, but this alone would result in the overall weight and weight difference between the intake valve side and the exhaust valve side. This results in a large difference in inertial mass. Therefore, the bounce rotation speed is limited by either the intake valve side or the exhaust valve side, and it is difficult to sufficiently increase the bounce rotation speed of the entire valve train.

The present invention aims to solve these problems all at once.

[0007]

[Means for Solving the Problems] In order to achieve the above object, the present invention takes the following measures.

That is, in the valve train system for an internal combustion engine according to the present invention, an intake valve and an exhaust valve disposed in a cylinder head are connected to each other via a pivot type rocker arm having a fulcrum on the same side of the cylinder head. The valve is configured to be driven to open and close, and the valve farther from the fulcrum is lighter than the valve closer to the fulcrum.

[0009]

[Operation] According to such a structure, the rocker arm for driving the opening and closing of the valve farther from the fulcrum is longer than the rocker arm for driving the opening and closing of the valve closer to the fulcrum, The inertial mass during operation is greater than that of the shorter rocker arm. However, since the valve driven to open and close by the longer rocker arm is lighter, its inertial mass can be smaller than that of the valve closer to the fulcrum.

On the other hand, since the valve closer to the fulcrum is heavier than the valve farther from the fulcrum, the inertial mass during operation is larger than the valve farther from the fulcrum. However, the rocker arm for opening and closing the valve closer to the fulcrum is
Since it is lighter than the longer rocker arm, its inertial mass can be reduced.

[0011] With such a structure, it becomes possible to reduce the overall weight and inertial mass on the intake valve side and the exhaust valve side, and to achieve good balance.

0012

DESCRIPTION OF THE PREFERRED EMBODIMENTS A case in which an embodiment of the present invention is applied to an automobile engine will be described below with reference to the drawings.

Valve train system 1 of the engine schematically shown in FIG.
This is constructed so that an intake valve 3 and a plurality of exhaust valves 4 provided in a cylinder head 2 are respectively driven to open and close by a single camshaft 7 via a plurality of pivot-type rocker arms 5 and 6. be.

[0014] The cylinder head 2 is connected to a cylinder block 8.
It is fixed on the top and has a flat bottom surface 2a. This bottom surface 2a has a top surface 9a of the piston 9 at the top dead center.
A recess 11 forming a combustion chamber 10 is provided between the two. As shown in FIGS. 1 and 3, the recess 11 is a half-moon-shaped recess provided on the intake side, and the intake valve 3 is disposed in the center of the upper surface 11a. However, this recess 11 is
Intake passage 13 with the tip of the injector 12 facing in the middle
is connected to. As shown in FIG. 3, spark plugs 14 are arranged on both sides of the intake valve 3, respectively.

The intake valve 3 is driven to open and close by the longer rocker arm 5 in the direction of operation of the piston 9, and as shown in FIG. 3, one intake valve is arranged for each cylinder. be. This intake valve 3 is smaller and lighter than the exhaust valve 4.

The exhaust valves 4 are driven to open and close in the operating direction of the piston 9 by the shorter rocker arm 6, and as shown in FIG. 3, two are arranged for one cylinder. be.

Each rocker arm 5, 6 has a slipper surface 5a, 6 on its upper surface that engages with the cam surface 7a of the camshaft 7.
a, and one end is pivotally connected to the upper end of a lash adjuster 15 disposed on the exhaust side of the cylinder head 2. Each pivot portion is used as a fulcrum 16 to be swung by a camshaft 7.

According to this configuration, the rocker arm 5 for driving the intake valve 3 to open and close is longer than the rocker arm 6 for driving the exhaust valve 4 to open and close, so that the inertial mass during operation is greater than that of the exhaust gas. It is larger than the rocker arm 6 for the valve. However, since the intake valve 3 is lighter than the exhaust valve 4, its inertial mass is smaller than that of the exhaust valve 4.

On the other hand, since the exhaust valve 4 is heavier than the intake valve 3,
The inertial mass during operation is larger than the intake valve 3, but since the exhaust valve rocker arm 6 is lighter than the intake valve rocker arm 5, its inertial mass is smaller than the rocker arm 5.

Therefore, with such a device, it is possible to make the inertial mass of the entire intake valve side substantially equal to the inertial mass of the entire exhaust valve side, and to make the entire inertial mass on both sides effective. can be reduced to As a result, the followability of the entire valve train on the intake valve side and the exhaust valve side can be improved, and the bounce rotation speed can be effectively increased.

In this embodiment, a recess 11 is formed on the intake side of the bottom surface 2a of the cylinder head 2.
An intake valve 3 is disposed on the bottom surface 2a, and an exhaust valve 4 is disposed on the bottom surface 2a. These are connected to pivot type rocker arms 5 and 6 having a fulcrum 16 on the same side of the cylinder head 2.
A single camshaft 7 disposed above the piston 9 drives the piston 9 to open and close in the operating direction. Therefore, the entire valve train and the cylinder head 2 can be made particularly compact compared to conventional ones.

[0022] Also, the combustion chamber 10 and the intake/exhaust valves 3, 4
If the configuration is as described above, the intake valve 3 and the exhaust valve 4
A wall surface 11b of the recess 11 exists between the intake valve 3 and the exhaust valve 4, and the intake valve 3 and the exhaust valve 4 are opened and closed at different positions in the operating direction of the piston 9. Therefore, when the intake valve 3 and the exhaust valve 4 overlap, the air-fuel mixture introduced through the intake valve 5 does not immediately blow through to the outside through the exhaust valve 4. Incidentally, in the conventional type, since the intake valve and the exhaust valve are close to each other at substantially the same position, there is a problem that air-fuel mixture blows through.

Furthermore, the combustion chamber 10 is formed on the intake valve side and is compact. Furthermore, since the air-fuel mixture is forcibly forced into the combustion chamber 10 from the squish area 17 on the exhaust valve side as a hot squish, air and fuel are effectively agitated. As a result, the combustion speed of the air-fuel mixture can be increased, and the compression ratio can be increased without difficulty, thereby increasing thermal efficiency and achieving low fuel consumption. In particular, if the intake valve 3 is made single and the spark plugs 14 are arranged on both sides of the intake valve 3 as in the above embodiment, not only can ignition be ensured, but also the air flow from the spark plug 14 to the end of the combustion chamber 10 can be ensured. Distance can be shortened. Therefore, together with the compact combustion chamber 10, the combustion period can be effectively shortened, and rapid combustion can be achieved.

[0024] The engine may be a four-stroke engine, a two-stroke engine, or a variable cycle engine.
It can be used as an engine. Hereinafter, aspects in which the engine is used as a two-cycle engine or a variable-cycle engine will be schematically explained. In addition,
In the following description, the same reference numerals will be used for parts that overlap with those in the above embodiment, and the description will be omitted. When used as a two-stroke engine, a supercharger is used to introduce compressed air into the cylinder, and the opening and closing timings of the intake valve 3 and exhaust valve 4 are set approximately as follows. When the piston 9 is moving from the top dead center to the bottom dead center, the exhaust valve 3 is opened to start blowdown. After a certain blowdown period, the intake valve 3 begins to open just before the piston 9 reaches the bottom dead center to begin scavenging. After a certain scavenging period, the exhaust valve 4 is closed. After supercharging the air-fuel mixture into the cylinder for a certain period of time, the intake valve 3 is closed, and the air-fuel mixture is ignited by the ignition plug 14 just before the piston 9 reaches top dead center.

When the engine is used as a variable cycle engine, it is used in the following manner. Here, a variable cycle engine means that, for example, when the engine is under high load, there is a combustion stroke every time the crankshaft rotates once, and when the engine is under low load, there is a combustion stroke during multiple revolutions of the crankshaft. refers to an engine with a combustion stroke of When the engine is under high load, combustion and gas exchange occur in the same manner as in the two-stroke engine described above. That is, when the intake valve 3 is opened, the necessary amount of fuel is injected from the injector 12,
Combustion takes place. On the other hand, when the engine is under low load, the air cycle in which only air is introduced into the cylinder during intake, and the combustion cycle in which the air-fuel mixture is supplied to the cylinder and combusted are performed every time the crankshaft rotates once. Do this alternately. In this case, it is preferable that the fuel injection be completed before the intake valve 3 closes, so that the fuel adhering to the intake valve 3 and the like can be forced into the cylinder using compressed air. In the air cycle, when the intake valve 3 is opened, no fuel is injected from the injector 12, and only air compressed by the supercharger is supercharged into the cylinder. Then, only the air is compressed and expanded, and the inside of the cylinder is scavenged with the air. After that, the combustion cycle described above again starts.

According to this variable cycle engine, the inside of the cylinder is cleaned using only air at low load to exhaust residual gas, and then the air-fuel mixture is introduced into the cylinder, so there is no problem caused by the influence of residual gas. Simultaneous combustion can be prevented and emissions etc. can be improved. Furthermore, like a four-stroke engine, fuel only needs to be supplied once during two revolutions of the crankshaft, so fuel consumption can be reasonably suppressed. At high loads, combustion occurs every time the crankshaft rotates, similar to a two-stroke engine, and energy is output each time.
Engine output can be increased.

[0027]

[Effects of the Invention] Since the present invention has the above-described configuration, in a valve train having rocker arms of different lengths,
The bounce rotational speeds on the intake valve side and the exhaust valve side can be effectively increased, and the bounce rotational speeds on the intake valve side and the exhaust valve side can be made approximately equal. As a result, the followability of the entire valve train system and the permissible engine speed can be improved, and high output can be achieved.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing one embodiment of the present invention.

FIG. 2 is a plan view of a valve train showing an embodiment of the present invention.

FIG. 3 is a bottom view of a cylinder head showing one embodiment of the present invention.

[Explanation of symbols]

1...Valve train system 2...Cylinder head 3...Intake valve 4...Exhaust valve 5...Rocker arm 6...Rocker arm 16...Fulcrum

Claims (1)

[Claims] 1. A valve train for an internal combustion engine, in which an intake valve and an exhaust valve disposed in a cylinder head are respectively opened and closed via a pivot type rocker arm having a fulcrum on the same side of the cylinder head. 1. A valve train system for an internal combustion engine, characterized in that a valve farther from the fulcrum is lighter than a valve closer to the fulcrum.