JPS6321809B2 - - Google Patents

Description

[Detailed description of the invention] Industrial applications The present invention relates to a four-stroke internal combustion engine.

BACKGROUND TECHNOLOGY Conventionally, an engine with a multi-cylinder arrangement has been deactivated during partial load operation by deactivating some of the cylinders, for example, deactivating 3 cylinders out of 6 cylinders, that is, stopping the fuel supply and rendering them inactive. There are some systems that reduce friction by closing the intake and exhaust valves of the cylinder, but since the piston normally moves back and forth while the intake and exhaust valves are closed, the pressure inside the blocked cylinder is reduced by blow-by. The pressure gradually decreases, and the pressure inside the cylinder becomes negative. This negative pressure state causes oil to be sucked into the cylinder through the gap between the piston ring and the cylinder liner, increasing oil build-up. Then, when the cylinder is put into operation, the oil that has been pumped up burns or explodes, creating an unfavorable situation.

To deal with this, the system consists of a bypass communication passage that connects the combustion chamber and the exhaust passage, and a valve device that is provided in the middle of the communication passage and opens and closes the communication passage in conjunction with the fuel injection device, and is operated during operation. Japanese Unexamined Patent Application Publication No. 134115/1983 discloses a cylinder number control engine configured to introduce exhaust gas into cylinders that are inactive, thereby reducing pumping loss and suppressing the inflow of fuel from active cylinders. The present invention is equipped with an intake valve control means for holding the intake valves of the cylinders closed and deactivating the partial cylinders, and an exhaust gas introduction control means for introducing exhaust gas into the cylinders during the intake stroke of the deactivated partial cylinders, thereby reducing pumping loss. A multi-cylinder internal combustion engine with cylinder number control that can reduce the amount of oil and prevent oil rise and fall was published in Japanese Patent Application Laid-Open No. 1983-
Publication No. 69737 discloses that in a multi-cylinder engine equipped with a device that stops operation by cutting off the supply of fuel and fresh air to some cylinders when the engine is under low load, the combustion chambers and exhaust system of these cylinders that are inactive during partial cylinder operation are disclosed. A cylinder number control engine was developed in 1983, which reduced pumping loss and eliminated the risk of large amounts of oil flowing into the combustion chamber.
Each is described in Publication No. 93933.

However, all of these systems introduce exhaust gas into cylinders whose operation is suspended during operation.

Further, in an internal combustion engine equipped with a fuel injection pump and a device that interrupts fuel injection to some of the cylinders of a multi-cylinder, the valves of some of the cylinders whose fuel injection is interrupted are slightly opened when the fuel injection is interrupted. JP-A-52-135903 describes an internal combustion engine that is equipped with a holding device to prevent cylinders that are not in regular operation from performing compression work and to reduce friction during startup.

However, this was designed so that the gas in the combustion chamber was pushed out to the atmosphere when the piston rose, and did not prevent oil buildup into the cylinder.

Problems to be Solved by the Invention An object of the present invention is to supply oil to the cylinders of an engine that is at rest during partial load operation without providing equipment for introducing exhaust gas into the cylinders that are not in operation during operation. An object of the present invention is to provide a four-stroke internal combustion engine that can prevent an increase in pumping loss and reduce pumping loss.

Means for Solving the Problems The four-stroke internal combustion engine of the present invention has at least one of the intake valve and the exhaust valve of a cylinder in a rest state during partial load operation, and only slightly closes just before the bottom dead center of the piston. It has a configuration characterized in that the pressure inside the cylinder is replenished by changing the operating timing of the valve so that it opens.

Embodiments Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

The graph in Figure 1 shows the valve timing, or operating characteristics, of the intake and exhaust valves during normal operation of the engine, with the horizontal axis X representing the crank angle and the vertical axis Y representing the valve lift of the intake and exhaust valves. ing. Crank angles from 0 degrees to 180 degrees correspond to the engine's suction stroke, crank angles from 180 degrees to 360 degrees correspond to the engine's compression stroke, crank angles from 360 degrees to 540 degrees correspond to the engine's expansion stroke, and crank angles from 540 degrees to 720 degrees. corresponds to the exhaust stroke of the engine. During operation of this engine, the operating characteristics of the intake valve follow the curve indicated by number 10, and the operating characteristics of the exhaust valve follow the curve indicated by number 11.

The graph in FIG. 2 shows the operating characteristics of the intake valve or exhaust valve in the internal combustion engine according to the present invention. Similar to FIG. 1, the horizontal axis X is the crank angle and the vertical axis Y is the valve of the intake valve or exhaust valve. It represents a lift. The crank angle and engine operating stroke are the same as in FIG. The operating characteristics of the intake valve and exhaust valve shown in FIG. 2 are such that at least one of them opens slightly near the end of the intake stroke, that is, just before the bottom dead center of the piston. Such operating characteristics prevent the pressure in the cylinder when the engine is at rest from gradually decreasing due to blow-by; that is, when at least one of the intake valve and the exhaust valve opens, Since air is introduced into the cylinder, there will be no increase in oil buildup inside the cylinder.

An embodiment of a device that allows at least one of the intake valve and the exhaust valve to exhibit the above operating characteristics is shown in FIGS. 3 and 4.

A pair of cams 1 are connected to the Rotsuker arm 5 during normal operation.
It consists of a cam 8 that engages with one end of the rocker arm 5, and a cam 7 that engages with one end of the rocker arm 5 during partial load operation. The other end of the rocker arm 5 engages with the intake valve 3. The rocker arm 5 is pivotally connected to the rocker shaft 6 so as to be movable in its axial direction. The axial movement of the Rotsuker arm 5 is
This is done by actuating the actuator 9 depending on whether the engine is in normal operation or partial load operation. In the figure,
4, 12, and 13 indicate springs. Cam 1 rotates in the direction of arrow A, and cam 8 has its maximum valve lift around 90 degrees of crank angle, and cam 7 rotates in the direction of arrow A.
is adjusted so that the maximum valve lift is achieved just before the crank angle of 180 degrees. Of course, it is also possible to move the camshaft instead of moving the rocker arm as described above.

In addition, when the cam 8 is used for an exhaust valve, its maximum lift may be set at a crank angle of 630 degrees, and the intake valve 3 may be replaced with an exhaust valve.

Effects of the Invention With the above configuration, the four-stroke internal combustion engine of the present invention does not introduce exhaust gas into cylinders that are not in operation during operation, reduces pumping loss, and at the same time prevents an increase in oil buildup into the cylinders. During subsequent engine operation, the oil in the cylinders may burn, increasing oil consumption.
Unfavorable conditions that could cause an unauthorized combustion explosion do not occur.

[Brief explanation of the drawing]

Figure 1 shows the valve timing during normal operation of the engine, Figure 2 is a graph showing the valve timing during partial load operation of the engine, and Figure 3 shows the relationship between the cam rocker arm and the intake and exhaust valves. The top view, FIG. 4, shows the front view of FIG. 3...Intake valve, 5...Rotzker arm, 7...
cam.

Claims (1)

[Claims] 1. During partial load operation, the operating timing of at least one of the intake valves and exhaust valves of the cylinders in the idle state was changed to allow them to open slightly only just before the bottom dead center of the piston, thereby replenishing the pressure in the cylinders. A 4-stroke internal combustion engine featuring: