JPH0364613A - Exhaust gas purifying device for two cycle engine - Google Patents

Abstract

PURPOSE:To quickly accelerate the reaction of catalysts while exhaust gas is controlled to be low in temperature by closing a revolving valve mounted on an exhaust port, thereby flowing exhaust gas to the catalysts through a slender pipe when an engine is warmed up just after it has been started. CONSTITUTION:A revolving valve 2 is mounted on the exhaust port 1 of an engine so that it can be actuated from outside by a wire 3, and a cut-out 5 in an inverted U-shape configuration is concurrently formed at one place in the lower side of a valve face 4. The forward end of an expansion chamber 6 is connected with the exhaust port 1, a slender pipe 7 is interposed in parallel within the expansion chamber 6, and the forward end of the slender pipe 7 is faced just to the rear section of the cut-out 5. In addition, a muffler 9 is connected with the rear end of the expansion chamber 6, and catalysts 10 are concurrently interposed to the front section of the muffler 9. Exhaust gas is concentrated into the cut-out 5 and the slender passage 7 so that it passes through with the revolving valve 2 closed when the engine is warmed up just after it has been started. By this constitution, exhaust gas is controlled to be low in temperature so that the reaction of the catalysts 10 can be accelerated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an exhaust gas purification device for a two-cycle engine.

[Conventional technology]

In a four-cycle engine and a two-cycle engine, a catalyst is attached to the exhaust system, and the exhaust gas is passed through the catalyst so that unburned components contained in the exhaust gas are oxidized and purified by the catalyst. Since the temperature of the exhaust gas in a two-cycle engine is lower than that in a four-cycle engine, a catalyst is installed immediately after the exhaust hole of the engine to raise the temperature at which the catalyst can react.

[Problem to be solved by the invention]

A two-cycle engine has an expansion chamber connected to the exhaust pipe connected to the engine exhaust hole, or the front end of the expansion chamber is connected directly to the exhaust hole, and the exhaust gas is intermittently exhausted when the engine rotates to obtain high output. The volume of the expansion chamber is matched to the pulsating waves of gas, and the atrium prevents gas from entering, ensuring high output. However, if the catalyst is installed immediately after the exhaust hole, the effect of the expansion chamber on the rear side will be reduced, the effect of utilizing the pulsation of exhaust gas will be reduced, and the output of the engine will be significantly reduced.

In view of the above, this invention has been developed to provide a two-cycle engine in which a catalyst is installed in front of the muffler on the rear side of the expansion chamber so as not to impair the exhaust pulsation effect, and the reaction of the catalyst can be started in a short time after starting. The purpose is to obtain an exhaust gas purification device.

[Means to solve the problem]

In order to achieve the above object, the exhaust gas purification device for a two-cycle engine of the present invention includes a rotary valve provided in an exhaust hole of a two-cycle engine, a notch provided in the rotary valve, and connected to the exhaust hole. Thin pipes are arranged in parallel inside the expansion chamber, the tips of the thin pipes are placed close to the notch, and the catalyst is attached to the front part of the muffler connected to the rear end of the expansion chamber.

[Effect]

When the engine is started and warmed up, if the rotary valve is closed, only the notch is open and exhaust gas flows through the notch.

Immediately after the notch, the tip of a thin pipe is opened, and most of the exhaust gas flows through the thin pipe. With thin pipes, the expansion of exhaust gas can be reduced, reducing the drop in temperature and allowing the thin pipes to heat up at an early stage. Then, exhaust gas with a small temperature drop is released from the rear end of the thin pipe, and the catalyst portion facing the rear end of the thin pipe is heated intensively, so that the catalyst quickly reaches the reaction temperature. When a catalyst starts a reaction, it generates heat and its temperature rises, and the reaction rapidly spreads throughout the catalyst. When the catalyst has completely reacted, a temperature sensor installed behind the catalyst causes a servo motor to fully open the rotary valve and resume normal operation. At this time, exhaust gas flows throughout the fat expansion chamber, and the engine output can be increased due to the effect of utilizing the pulsation of the exhaust gas.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

A rotary valve 2 is rotatably attached to an exhaust hole 1 of a two-cycle engine, and the rotary valve 2 is rotatably operated from the outside with a wire 3. The rotary valve 2 is provided with an inverted U-shaped notch 5 at a lower portion of the valve surface 4. The front end of the expansion chamber 6 is connected to the exhaust hole 1 . The expansion chamber 6 has a rear cross section that is widened and has the same shape as the expansion chamber 6. Inside the expansion chamber 6, there is a thin pipe 7.
are installed in parallel. The thin pipe 7 is provided with ribs 8, and the ribs 8 are inserted between the outer plates stacked and welded in the middle of forming the expansion chamber 6.
They are sandwiched together and welded together. thin pipe 7
The front end of the rotary valve 2 is made to protrude from the front end of the expansion chamber 6.
Align it immediately after notch 5. A muffler 9 is connected to the rear end of the expansion chamber 6. A catalyst 10 having a catalyst agent adhered to a honeycomb-shaped carrier is attached to the front part of the muffler 9. catalyst 10
A temperature sensor 11 is attached to the rear side, and the rotary valve 2 is operated via a servo motor or the like.

As shown in FIGS. 1 and 2, when the rotary valve 2 is closed, only the notch 5 is open, and the exhaust gas flows through the notch 5.
, most of it flows through the thin pipe 7, expansion is limited, temperature drop is small, the thin pipe 7 is heated in a short time, and exhaust gas with a small temperature drop is released from the rear end of the thin pipe 7. Become so. Then, the reaction starts from the part of the catalyst 10 facing the thin pipe 7, and the reaction spreads to the entire catalyst 10 due to the heat generated by the reaction. When the temperature sensor 11 senses the temperature increase due to the reaction, as shown by the arrow in FIG.
Turn the valve surface 4 of the rotary valve 2 upward twice to fully open it.

Then, the exhaust gas comes to flow throughout the fat expansion chamber 6.

〔Effect of the invention〕

As explained above, since the present invention is configured as described above, the exhaust gas can be concentrated and passed through the thin pipe during warm-up operation after startup, and the temperature drop of the exhaust gas can be minimized, resulting in an early start. By heating a thin pipe, the reaction starts from the part of the catalyst facing the thin pipe, and the heat generated by the reaction spreads the reaction throughout the entire body, making it possible to purify exhaust gas. When the catalyst is able to continue the reaction by generating heat, the rotary valve is opened to allow exhaust gas to flow into the expansion chamber, and the pulsation of the exhaust gas can be used to generate high output. In addition, the muffler can be made into a simple cylindrical shape, making it easy to hold the catalyst, and the catalyst can be replaced at low cost.

[Brief explanation of drawings]

The figures show one embodiment of the present invention, Fig. 1 is a vertical side view of the engine section, Fig. 2 is a front view of the rotary valve section, Fig. 3 is a perspective view of the rotary valve, and Fig. 4 is an exhaust Figure 5 is a longitudinal cross-sectional view of the entire system, Figure 5 is a cross-sectional view of the expansion chamber, and Figure 6 is a partial perspective view of a thin pipe. 1... Exhaust hole, 2... Rotating valve, 5... Notch, 6... Expansion chamber, 7... Thin pipe, 9... Muffler, 10... Catalyst.

Claims (1)

[Claims] A rotary valve is installed in the exhaust hole of a two-stroke engine,
A notch is provided in the rotary valve, thin pipes are placed in parallel inside the expansion chamber connected to the exhaust hole, the tips of the thin pipes are brought close to the notches, and a catalyst is placed in front of the muffler connected to the rear end of the expansion chamber. An exhaust gas purification device for a two-stroke engine, characterized in that the device is adapted to be installed.