JPS58160539A - Secondary air introducing device of internal combustion engine - Google Patents

Abstract

PURPOSE:To maintain enhanced power output in a device, in which the secondary air is injected in cylinders at a point near the lower dead point of piston, by lessening the amount of counterflow of combustion gas into the secondary air intake port. CONSTITUTION:A secondary air intake port 19 is furnished in each cylinder 2 of an engine 1 at a locarion near the lower dead point of piston 3. Discharge hole 16 of an air pump 14 is connected with the secondary air intake port 19 through a secondary air introducing passage 17, and a one-way valve 20 is installed in each of branch passages 18 for said pair of secondary air introducing passage 17. Even though the combustion gas makes counterflow back to the secondary air intake port at the final stage of the expansion stroke, the amount of counterflow of combustion gas back to the secondary air intake port is suppressed to an ignorable amount to ensure maintenance of the enhanced power output, since inside of the cylinder is in communication with the atmosphere because the opening timing of the secondary air intake port is set so as to open when or after the exhaust valve is opened.

Description

[Detailed Description of the Invention] In order to not only completely burn the unused gas in the exhaust gas and improve the properties of the exhaust gas, but also to improve the output and torque characteristics of the engine from low to medium speed ranges to high speed ranges. This invention relates to a secondary air introduction device for an internal combustion engine that injects secondary air into a cylinder from near the bottom dead center of a piston.

In a conventional secondary air introduction device for an internal combustion engine, as shown in FIG. 1, a secondary air introduction port d is provided above the bottom dead center of a piston C in a cylinder b of an engine A discharge port e of an air pump e connected to and driven by a rotating part of the air pump e.

is connected to the secondary air inlet d via the discharge passage f, and a one-way valve g that allows air to pass only towards the inlet d is interposed in the discharge passage f, and the upper end of the piston C is connected to the secondary air inlet d. When the secondary air inlet d is opened by passing through the secondary air inlet d from above to below, the air pumped by the air pump θ passes from the secondary air inlet d to the cylinder b via the one-way pulp g. It was to be introduced internally.

However, in the conventional secondary air introduction device, since the secondary air introduction port d is opened before the exhaust valve is opened, the high-pressure combustion gas exploded within the pulling cylinder b is transferred to the secondary air introduction port d. The air flows from the air inlet d to the one-way pulp g in the discharge passage f, and the volume component therebetween does not perform any effective work, the increased energy is wasted, and the output characteristics, torque characteristics, and fuel efficiency of the engine deteriorate.

The present invention relates to an improvement of a secondary air introduction device for an internal combustion engine that eliminates such inconveniences.

An embodiment of the present invention illustrated in FIGS. 2 to 6 will be described below.

3 is a four-cycle gasoline engine for a motorcycle, and a secondary air inlet 19 is provided near the bottom dead center of a piston 3 in a cylinder 2 of the engine 1.

Further, a small end of a connecting rod 5 is pivotally connected to the piston 3 via a piston pin 4, a large end of the connecting rod 5 is pivotally connected to a crank 7 via a crank pin 6, and an intake pulp 9 is connected to the cylinder head 8. And when the exhaust pulp 10 is installed, the overhead camshaft 7
) 11 (see Figure 3) is pivotally mounted, and the camshaft 11
Pulp opening/closing cams 12 and 13 are attached to the intake valve 9, and as shown in FIG. The intake valve 9 is closed at β0 after bottom dead center, and in the exhaust valve 10, the pulp starts to open as an exhaust stroke at β0 before bottom dead center, and is closed at α0 after top dead center. And the pulp timing of the exhaust valve 10 is set, and the exhaust stroke and the intake stroke each have an interval (pulp overlap) in which the pulp is released.

Further, the vane type air t'>F1 is attached to the camshaft 11.
4 (see Figure 2) are connected, and the vane type air pump 1
The suction port 15 of the air pump 14 is connected to an air cleaner (not shown), and the discharge port 16 of the air pump 14 is connected to the secondary air introduction port 19 via the secondary air introduction passage 17. Bifurcated branch passage 18 of secondary air introduction passage 17
One-way pulp 20 is inserted into the container.

Therefore, the lower edge 19a of the secondary air inlet 19 is
It is located at the upper edge 3a of the piston 3 at the bottom dead center, and the upper edge 19b of the secondary air inlet 19 corresponds to the position of the upper edge 3a of the piston 3 at the part where the exhaust pulp 10 begins to be released. It is now set to the location where it was set.

When this is expressed numerically, it is expressed as the secondary air inlet 19.

Note that R: Crank rotation radius L: Connecting rod length θ: Crank angle when the exhaust valve IO starts to open, in this example, β0 from the bottom dead center. Therefore, to explain based on the operating stroke, the secondary air inlet 191F starts opening at 2β0 before the end of the suction stroke (β0 from the bottom dead center), and at the same time as the suction stroke ends, or the suction valve closes. Since the secondary air inlet 19 is closed before the valve, the air pressurized by the vane type air pump 14 flows through the secondary air inlet passage 17, the bifurcated branch passage 18,
The air is introduced into the cylinder 2 through a one-way valve and a secondary air introduction port 19.

Therefore, compared to an engine with a conventional compression ratio that does not introduce secondary air, extra air is supplied by the amount of air introduced by the vane type air pump 14 during this period. The effective indicated pressure of the expansion stroke in the example (dotted chain line px) is significantly increased compared to that of the conventional compression ratio without secondary air introduction (solid line py). Furthermore, according to this embodiment, even if the volume in the two-way branch passage 18 between the secondary air inlet 19 and the one-way valve is large enough, this can be done in synchronization with the opening of the exhaust valve 10 during the expansion stroke. At the same time, the secondary air inlet 19 opens, so that the combustion gas in the two-way branch passage 18 will not flow backwards, and a drop in the effective operating pressure can be avoided.

For the reasons described above, the output characteristics, torque characteristics, and fuel efficiency of the engine can be improved.

Further, since secondary air is introduced into the cylinder 2 by the vane type air pump 14 from the end of the expansion stroke to the beginning of the exhaust stroke in the same way as described above, unburned gas is oxidized and the properties of the smoldering gas are improved. Ru.

As described above, the present invention provides a reciprocating internal combustion engine that has an intake valve and an exhaust valve near the top dead center of a piston, and also has a secondary air inlet on the inner wall of the cylinder near the bottom dead center of the piston. In 1, the opening timing of the secondary air inlet is set to be opened at the same time as the opening timing of the exhaust valve or after the exhaust valve is opened, so that the secondary air inlet is opened at the end of the expansion stroke. Even if the combustion gas flows back into the secondary air inlet, the inside of the cylinder is communicated with the atmosphere through the exhaust valve and the exhaust pipe, so even if the combustion gas flows back into the secondary air inlet, combustion will not flow into the exhaust pipe. The amount of gas discharged is overwhelmingly large, and the amount of backflow of combustion gas into the secondary air inlet is negligibly small, so the effective work in the expansion stroke is maintained, and the output increase due to the introduction of secondary air is reduced. effectively maintained, improving engine output, torque characteristics, and fuel efficiency.

Although the present invention has been described above in detail with reference to the embodiments illustrated in the drawings, the present invention is not limited to such embodiments, and can be freely modified as necessary without departing from the spirit of the present invention. The design can be modified.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram schematically illustrating a conventional secondary air introduction device for an internal combustion engine, and FIG. 2 is a part of an internal combustion engine equipped with an embodiment of the secondary air introduction device for an internal combustion engine according to the present invention. A cutaway side view, Figure 3 is a vertical side view of the main part, Figure 4 is a vertical side view of the main part when the piston is at F dead center, and Figure 5 is the moment when the secondary air inlet is closed. FIG. 6 is a partial cross-sectional plan view of the engine in the above embodiment, FIG. 7 is an explanatory diagram illustrating the opening/closing timing of the anchor air pulp and the secondary air inlet, and FIG. is a p-v diagram of a conventional internal combustion engine and an internal combustion engine equipped with this embodiment. ■... Four-cycle gasoline engine, 2... Cylinder, 3... Piston, 4... Piston pin, 5...
・Connecting rod, 6... Crank pin, 7.
... Crank, 8... Cylinder head, 9... Intake Harz, 10... Exhaust valve, 11... Overhead camshaft, 12.13... Hartz opening/closing cam, 1
4... Vane type air pump, 15... Suction port, 16
...Discharge port, 17...Secondary air introduction passage, 1B...
・Two-pronged branch passage, 19...Secondary air inlet, addition...
One way valve. Agent: Patent attorney Nozomu Ehara and 1 other person Figure 5 Figure 6 Figure 1

Claims (1)

[Claims] In a reciprocating internal combustion engine that has an intake valve and an exhaust valve near the top dead center of the piston, and also has a secondary air inlet on the inner wall of the cylinder in the stroke area of the piston, the opening of the secondary air inlet A secondary air introduction device for an internal combustion engine, wherein the timing is set to open at the same time as the opening timing of the exhaust valve or after the opening of the exhaust valve.