JPS6313427Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a starting promotion device for a compression ignition internal combustion engine.

In order to start the above-mentioned compression ignition internal combustion engine, the temperature of the air after being compressed by the piston must be raised to above the ignition temperature of the fuel in the initial stage of startup, but the temperature after compression has a large influence on the initial compression temperature. Therefore, the starting performance of the internal combustion engine can be improved by increasing the initial compression temperature.

For this reason, various means have been considered in the past to increase the pre-compression temperature, and one of them, as shown in Japanese Utility Model Publication No. 36-12607, is to rotate the intake pipe at an appropriate location eccentrically from the center of the engine. Some have a butterfly valve attached to a freely adjustable shaft.

When starting, the intake pipe passage is constricted by the butterfly valve and the engine is rotated.The constriction causes the pressure inside the cylinder, which is subject to inflow resistance, to drop below atmospheric pressure, and intake air rapidly flows into the cylinder through the narrow passage. By doing so, the gas temperature can be increased. In principle, in a container a with a lid with a narrowed opening as shown in FIG.
After reducing the internal pressure to below atmospheric pressure, when lid b is opened, air is rapidly introduced into container a from the inlet, and this rapidly flowing air performs adiabatic compression work to compress the air inside the container. In this case, a device that increases the temperature inside the container a is applied.

By the way, in an engine with a large number of cylinders, there are cases where several cylinders are on the intake stroke at the same time.
In such an engine, in which intake air is supplied to each cylinder through one intake pipe, the intake air is rapidly introduced into a certain cylinder as described above, and the adiabatic compression work is performed as described above to lower the gas temperature. Even if you try to raise the piston, if the piston in another cylinder is in a descending state during the intake stroke, the intake air in the combustion chamber of the previous cylinder will be sucked out by the descent of the piston of that cylinder due to the communication of the intake pipe. In the end, no adiabatic compression work is done and the temperature inside the cylinder does not rise.

For this reason, in internal combustion engines provided with a throttle valve as described above, it has been common to have a structure in which a throttle valve is provided at the inlet of each cylinder in order to avoid the influence between the cylinders.
However, if each cylinder is equipped with a throttle valve, it goes without saying that the number of parts will increase, and since the throttle valve brings about the best effect by optimizing the throttle amount, all cylinders will have a uniform throttle amount. In order to do so, they had to be manufactured with great care and precision, which greatly increased product costs.

On the other hand, as shown in Japanese Utility Model Publication No. 52-71632, an on-off valve with a notch is provided in the exhaust pipe connected to the exhaust manifold of the engine, and this valve is operated at startup to close the exhaust gas and reduce the temperature inside the cylinder. However, exhaust gas remains, reducing suction efficiency, and in order to avoid engine stoppage, the on-off valve cannot be sealed, and a cutout is formed in a part of the valve, so the exhaust gas pressure is reduced. I can't raise it. In this regard, the technology disclosed in Japanese Patent Publication No. 51-34526 is that a two-stage cam is provided to open the exhaust valve for a short period from the end of the intake stroke to the beginning of the compression stroke, and when the intake valve of a certain cylinder is open, the exhaust valve is opened. According to exhaust gas recirculation technology that connects the exhaust pipes of other cylinders with valves open, it is possible to increase exhaust pressure without reducing intake efficiency, but since a portion of the exhaust gas is exhausted, the increase in exhaust pressure is small.

In view of the above, the present invention aims to increase the temperature due to the adiabatic compression work as described above easily and without reducing intake efficiency, and to improve starting performance. An opening/closing valve is provided in the engine so that the engine exhaust pipe is sealed via a control device when the starting switch is closed, and the engine exhaust valve is also opened between the end of the suction stroke and the beginning of the compression stroke by a two-stage cam. The present invention is configured such that the exhaust valve can be opened and closed, and the pressure gas from the exhaust valve to the opening/closing valve is introduced into the combustion chamber through the exhaust valve.

This will be explained below with reference to an illustrated embodiment. In FIGS. 2 and 3, reference numeral 1 denotes a cylinder of a compression ignition internal combustion engine, into which a piston 2 is slidably inserted. 3 is a combustion chamber, 4 is an intake valve, 5 is an exhaust valve, and 6 is a cam that interlocks with a crankshaft (not shown).

The intake valve 4 and the exhaust valve 5 are actuated by a tappet 7 lifted by a cam 6, a push rod 8, and rocker arms 9 and 10 swung thereby to open and close the intake passage 11 and the exhaust passage 12. do.

In this proposal, the cam 6 that operates the exhaust valve 5 is, in particular,
As shown by the solid line in FIG. 4, the exhaust valve 5 and the cam nose 6a operated during the normal exhaust stroke, the end of the intake stroke, for example, from 50 degrees before bottom dead center BDC to the beginning of the compression stroke,
For example, it is provided with a cam nose 6b that is particularly activated during a period of 70 degrees after bottom dead center BDC.

Reference numeral 13 denotes an exhaust pipe, and an on-off valve 14 is provided in the middle of the exhaust pipe, which is electromagnetically opened and closed by a control device 15 that is linked to the opening and closing of a starting switch 16. 1
7 is a power source, and when the start switch 16 is closed, a starter ST (not shown) rotates the crankshaft, and the control device 15 operates the on-off valve 14 to close the exhaust passage 13a.

Note that 18 is an intake pipe connected to the intake path 11.

Now, when the starter switch 16 is closed to start the engine, the starter ST rotates the crankshaft and at the same time the control device 15 operates the on-off valve 14 to seal the exhaust passage 13a. In this state, the intake valve 4 opens in a certain cylinder and the piston 2 begins to descend, but the inflowing intake air flows in while encountering inflow resistance from the intake valve 4, etc., so that the internal pressure of the combustion chamber 3 becomes atmospheric pressure. It becomes the lowest value near the bottom dead center.

On the other hand, since the interior of the exhaust passage 12 and the exhaust passage 13a is at least atmospheric pressure while the exhaust valve 5 is closed, the piston 2 from the end of the suction stroke to the beginning of the compression stroke is at the bottom dead center as shown in FIG. The cam nose 6 of said cam 6 is shown in FIG.
When the exhaust valve 5 is operated to open the exhaust passage 12 by b, the pressure of the pressure gas in the exhaust passage 12 is equal to or higher than the atmospheric pressure, and the pressure (negative pressure) in the combustion chamber 3 is increased.
Due to the pressure difference between
As a result, adiabatic compression work is performed in the combustion chamber 3 according to the above-mentioned theory, and the temperature of the intake air in the combustion chamber 3 is increased.

This increased intake air temperature becomes the initial temperature of the gas in the combustion chamber 3 immediately after it is compressed by the piston 2, and therefore increases the temperature after compression, so that the injected fuel can easily ignite. .

After ignition, as the engine rotational speed increases, the pressure in the exhaust passage 12 and the exhaust passage 13a further increases, and the adiabatic compression work also increases, so the temperature in the combustion chamber 3 increases accordingly, and complete combustion rapidly occurs. Close. When the start switch 16 is opened after the engine has completely exploded, the power to the starter ST is cut off and at the same time the spring 18
4 is quickly returned to the dashed line position in the figure, and the exhaust passage 1
3a is opened, so that when the exhaust valve 5 is subsequently opened during the intake stroke, the cam 6 will perform appropriate exhaust gas recirculation.

As described above, the present invention provides an on-off valve in the engine exhaust pipe so that the engine exhaust pipe is sealed via a control device when the start switch is closed, and the engine exhaust valve is controlled by a two-stage cam during the suction stroke. The valve is configured so that it can be opened even between the end of the compression stroke and the beginning of the compression stroke, and the pressure gas from the exhaust valve to the opening/closing valve is introduced into the combustion chamber through the exhaust valve. The structure is significantly simpler than when a valve was provided, and when the start switch is closed, the on-off valve is sealed to increase exhaust pressure and temperature, and when the above switch is opened, the on-off valve is immediately opened. It has the effect of allowing the engine to rev up without any hindrance, allowing the engine to operate smoothly, and also introduces the air in the exhaust passage from the opening/closing valve to the exhaust valve and the exhaust passage into the combustion chamber without reducing air intake efficiency. It also has the effect of increasing exhaust pressure.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram for explaining adiabatic compression work, Figure 2 is a sectional view of a compression ignition internal combustion engine showing an embodiment of the present invention, Figure 3 is an enlarged view of the main parts, and Figure 4 is a valve lift. It is an explanatory view showing a curve. 1...Cylinder, 2...Piston, 3...Combustion chamber, 4
...Intake valve, 5...Exhaust valve, 6...Cam, 13...Exhaust pipe, 14...Open/close valve, 15...Control device, 16...Start switch.

Claims (1)

[Scope of utility model registration request] An on-off valve is provided in the engine exhaust pipe so that when the start switch is closed, the engine exhaust pipe is sealed via a control device, and the engine exhaust valve is
A compression ignition internal combustion engine configured so that the valve can be opened even between the end of the suction stroke and the beginning of the compression stroke by a stage cam, and the pressure gas from the exhaust valve to the opening/closing valve is introduced into the combustion chamber via the exhaust valve. starting accelerator.