JPH01262321A - Exhaust diffuser of two-cycle engine - Google Patents

Abstract

PURPOSE:To reduce blown gas over an entire rotation range and increase output by a method wherein an aperture consisting of bendable plates is provided at the rear inside an exhaust diffuser and the aperture is rocked according to the number of engine rotations so that an aperture angle or the like is varied. CONSTITUTION:An exhaust diffuser 4 which is connected at the rear end of an exhaust pipe is formed in a taper shape, and a muffler 6 is connected to a tail pipe 5 at the rear part. The front end of a pair of right and left apertures 7 is fixed on the rear part inside the exhaust diffuser 4. On the other hand, a cam 10 fixed on a rotation shaft 9 of a motor 8 is provided on the exterior of the rear part of each aperture. A switch 11 for detecting the engine rotation is connected to the motor 8. In other words, the motor 8 is rotated according to the number of engine rotations so that inner protrusion amount of the aperture 7 is adjusted. This enables an aperture angle or the like to be varied until exhaust pressure is high enough to secure required reflection pressure waves, so that blown gas is reduced and output is increased.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an exhaust diffuser for a two-cycle engine that can be varied in accordance with the exhaust pulsation wave of the engine.

(Conventional technology and its problems) The exhaust system of a two-cycle engine has an important influence on the engine's output characteristics.The engine exhausts intermittently and rapidly, and the inside of the exhaust pipe is pulsating at first sight. Waves are generated.Furthermore, due to the structural features of a twin cycle engine, while the exhaust gas in the cylinder is exhausted through the air holes, fresh air is filled into the cylinder through the scavenging holes. Some of the fresh air may blow directly into the exhaust hole, and most of this fresh air blows through just before the exhaust hole closes.In the exhaust pipe (
By installing an air diffuser in series and adjusting the quality, thickness, and rear end throttle of this exhaust diffuser appropriately, the pressure vibration of the pulsating wave of the exhaust can be effectively utilized) ■ 1. The exhaust hole opens. Immediately before, by applying positive pressure near the exhaust hole to 1, the fresh air that can be blown is pushed back and filled into the cylinder, increasing the filling efficiency of the fresh air, increasing the engine output. Generally, the frequency of the exhaust pulsating waves changes with changes in the rotational speed, so the exhaust diffuser only works effectively within a certain rotational range. Normally, the length, volume, and rear aperture that become effective are set when the engine is at maximum output.

Therefore, it has no effect in other rotation ranges. To compensate for this, some exhaust pipes have a subtire bar in the middle of the exhaust pipe. For example, see JP-A-60-101221. Also, exhaust day-11
- Some models have a movable plate at the rear that can move in the forward direction. For example, see Japanese Utility Model Application No. 62-3930. Furthermore, some exhaust diffusers have variable volume. For example, see JP-A-62-135828. Although it is effective to set the frequency of the exhaust pulsating wave to 14 nodes in the nub chamber and to vary the length and volume of the exhaust diffuser according to the rotation, it is not yet fully satisfactory.

(Purpose of the Invention) This invention shows that varying the volume of the exhaust diffuser according to the rotation speed is effective in increasing output, but furthermore, the aperture angle at the rear end of the exhaust diffuser effectively reflects reaction force vibration. Focusing on the fact that it can be changed, we created an exhaust diffuser for a two-cycle engine that can produce high output over a wide rotation range by installing a diaphragm at the rear of the exhaust day-use -1F- that can change the aperture angle according to the rotation speed. purpose.

[Structure of the invention] Hereinafter, the present invention will be explained with reference to embodiments shown in the drawings.

1 and 2 show one embodiment of the present invention. Exhaust pipe 3 connected to the exhaust hole 2 of the two-cycle engine 1
An exhaust daylight 11-4 is connected to the rear of the engine. The exhaust diffuser 4 is tapered to gradually widen at the front, and tapered to gradually narrow at the rear, and each muffler 6 is connected to the tail pipe 5. The front end of an aperture 7 made of movable plates such as spring plates on the left and right sides is fixed to the internal rear part of the exhaust diffuser 4. A cam 10 mounted on a shaft 9 rotated by a motor 8 is provided outside the rear part of the aperture 7. The motor 8 rotates the cam 10 when the rotation detection switch 11 is energized, so that the rear part of the diaphragm 7 can be pushed inward as shown by the two-dot chain line in FIG.

FIGS. 3 and 4 show other embodiments of the present invention. In this case, a diaphragm 7 is provided in which band-shaped flexible plates such as spring plates are partially overlapped like a camera shutter, and a movable ring 1 is placed on the outside of the rear part of the diaphragm 7.
2, the movable ring 12 is pushed out by a rod 13 connected to a motor 8, and the motor 8 is energized by a rotation detection switch 11. The other parts are the same as those shown in FIGS. 1 and 2.

[Action of the invention]

The length and volume of the exhaust diffuser 4 and a portion of the taper at the rear end are set to be optimal for low speeds, so that reflected waves can be effectively utilized and output can be improved in the low speed range. In the high speed range, the rotation detection switch 11 drives the motor 8 to rotate the cam 10 or the movable ring 1
2 is pushed out and moved forward, the aperture 7
As shown by the two-dot chain line in the figure, it is pushed inward and bent, the taper angle at the rear becomes larger, and the aperture becomes stronger. When this happens, the exhaust pressure increases and reflected pressure waves suitable for the high rotation range can be obtained. In this way, even at high speeds,
The atrium allows for less gas and higher output.

(Effects of the Invention) As explained above, the present invention provides an exhaust diffuser that is connected to the exhaust pipe connected to the end of the exhaust port of the engine, and a diaphragm that is provided with a flexible plate at the rear of the exhaust diffuser.
Since the diaphragm is movable in relation to the rotational speed of the engine, by moving the diaphragm, the diaphragm angle and the opening area at the rear end of the diaphragm can be varied in accordance with the rotational speed. In particular, the aperture angle has a large effect on the influence of reflected waves, and at both high and low speeds, the reflected waves can reduce gas in the atrium and increase engine output.

[Brief explanation of the drawing]

1 and 2 show one embodiment of the present invention, in which FIG. 1 is an overall side view, FIG. 2 is an enlarged longitudinal sectional plan view of the portion indicated by the arrow in FIG. 1, and the third factor and FIG. A third embodiment of the present invention is shown.
The figure is an enlarged ILIi plan view of the main part, and FIG. 4 is a side view of the same. 1...engine, 2...exhaust hole, 3...exhaust pipe,
4...Exhaust diffuser 17...Aperture. Figure 3

Claims (1)

[Claims] An exhaust diffuser is connected to the exhaust pipe connected to the end of the exhaust hole of the engine, and a diaphragm is provided at the rear of the exhaust diffuser using a flexible plate, and the diaphragm is movable in relation to the engine speed. Features a two-stroke engine exhaust diffuser.