JPS63195317A - Exhaust control device for two-cycle engine - Google Patents

Abstract

PURPOSE:To increase the output of an engine smoothly by arranging a plate in the hole cut through toward the upper wall of an exhaust port from a subchamber, and by engaging the rack of the plate with the pinion of a cylindrical valve. CONSTITUTION:A plate 6 is slidably arranged in the hole cut through toward the upper wall of an exhaust port 3 from a subchamber 4. The rack 6c formed on the back side of the plate 6 is engaged with the pinion 5b of a cylindrical valve 5. Thus, the volume of exhaust pipe and exhaust timing suitable for every revolution region can be secured, and the output of an engine can be smoothly increased over a wide range of revolution region.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] This invention relates to an air control device for a two-stroke engine.

[Conventional technology]

In a 2-stroke engine, exhaust is performed by a so-called scavenging stroke in which combustion gas is pushed out by the air-fuel mixture. Therefore, compared to an engine with an independent exhaust valve like a 4-stroke engine, gas exchange is more moderate, i.e., the mixture is not mixed. The drawback was that air could not be exchanged with exhaust gas. For this reason, in a 2-cycle engine, part of the air-fuel mixture comes out of the exhaust boat during exhaust (a so-called blowout phenomenon).
, the filling efficiency of the air-fuel mixture in the cylinder decreased, and it was not possible to improve the output over a wide range of rotation speeds. Conventionally, in order to prevent this type of blow-out phenomenon, a sub-chamber that changes the volume of the exhaust pipe is connected to the exhaust port, and the air-fuel mixture is drawn into the cylinder by the exhaust pulsating pressure generated in this sub-chamber. By improving the push-back and air-fuel mixture filling efficiency, the aim was to improve the output of the two-stroke engine over a wide range of rotation speeds.

By the way, even in the above-mentioned engine with a subchamber, the volume of the subchamber that synthesizes the optimal exhaust pulsation pressure for pushing back the air-fuel mixture differs depending on each rotation of the engine. It is extremely difficult to smoothly increase the output of a two-stroke engine over a wide range of rotations using only a chamber.

[Purpose of the invention]

In view of the above-mentioned problems, the present invention provides an exhaust control device that smoothly improves the output of a two-stroke engine over a wide range of engine speeds from low speeds to high speeds.

[Structure of the invention]

In order to solve the above-mentioned problems, the present invention includes a subchamber that communicates with an exhaust port, and a cylinder that is disposed between the subchamber and the exhaust port and that opens and closes between the subchamber and the exhaust port. Exhaust control of a two-stroke engine with a shaped valve
In the device, a hole is bored from inside the subchamber toward the upper wall of the exhaust port immediately after the cylinder side port, and a plate whose lower surface forms the upper wall of the exhaust port is slidably disposed in the hole. At the same time, a rack is formed on the back surface of the plate, and a pinion that meshes with the rack is formed on the circumferential surface of the cylindrical valve, and the cylindrical valve is rotated in a low rotational speed range of the engine to open the subchamber. and the exhaust port, the lower surface of the plate protrudes into the exhaust port to lower the upper edge position of the cylinder-side opening of the exhaust port, and set the exhaust timing later, When the cylindrical valve is rotated to close the space between the subchamber and the exhaust port in a high rotational speed range of the engine, the lower surface of the plate escapes from inside the exhaust port and the exhaust port is closed. The upper edge position of the cylinder-side opening is raised and the exhaust timing is set quickly, thereby simultaneously securing the tracheal volume and exhaust timing corresponding to each rotational speed range of the two-stroke engine.

〔Example〕

Hereinafter, one embodiment of the exhaust gas control device according to the present invention will be described in detail.

FIG. 1 is a sectional view of a main part of a two-stroke engine 2 equipped with an exhaust control system 1lvtW11 according to the present invention.

This exhaust control device ff1 is connected to the exhaust port 3 of the 2-stroke engine 2! A sub-chamber 4 for variable exhaust pipe volume is provided, a cylindrical valve 5 that opens and closes between the sub-chamber 4 and the exhaust port 3, and a cylindrical valve 5 that operates in conjunction with the cylindrical valve 5, Plate 6 that raises and lowers the upper edge position 3b of the frontage 3a
It is composed of. Of these, the plate 6 is slidably accommodated in a hole 7a bored from inside the subchamber 4 toward the upper wall 3C immediately after the exhaust port 3 formed in the cylinder block 7, and its lower surface 6a It forms part of the earthen wall 3C of port 3. The hole 7a has a substantially rectangular cross section as shown in view A in FIG. 1 and a west view of the main part in FIG. When it is slid and projected into the exhaust port 3, the upper edge 3b of the cylinder side opening 3a is apparently lowered by an amount H by the lower surface 6a, as shown in FIG. Further, a hole 5a is formed between the circumferential surfaces of the cylindrical valve 5 to communicate the subchamber 4 and the exhaust port 3. When the shaped valve 5 is rotated at a predetermined speed of the engine, the hole 5a and the circumferential surface of the valve 5 open and close the space between the subchamber 4 and the exhaust port 3, and the exhaust pipe volume changes.

On the other hand, interlocking means 8 is formed between the plate 6 and the cylindrical valve 5 to raise and lower the plate 6 in accordance with the rotation of the cylindrical valve 5.

This interlocking means 8 is connected to the second link shown in the enlarged perspective view of the main part in FIG.
As shown in the figure, it is composed of a rack 6C formed on the back surface 6b of the plate 6 and a pinion 5b that meshes with the rack 6c, and the pinion 5b is formed over the circumferential surface of the cylindrical valve 5. There is. Furthermore, as shown in Figure 3,
A groove 7b that allows the rack 6c to move is formed in the hole 7a that slidably accommodates the plate 6. In FIG. 1, reference numeral 9 denotes a cylinder head constituting a part of the subchamber 4. In FIG. 2, reference numeral 6d denotes a plate-shaped stopper erected at the rear end of the plate 6. As shown in the figure, when the plate 6 is engaged with the upper end 7C of the cylinder block 7, the movement of the plate 6 is caused by the cylinder fJ.
J 17il O The valve 5 is reliably stopped just before the group 3a, and the rotation of the cylindrical valve 5 beyond a predetermined rotation angle is also regulated by the engagement between the rack 6C and the pinion 5b.

Next, the operation of the above-described exhaust control device 1 will be explained, and the configuration will also be explained in more detail.

When the two-stroke engine 2 starts and its rotational speed range reaches a predetermined low/medium rotational speed range, the cylindrical valve 5 is stopped at the initial position shown in FIG. 1 at rotation Q by the driving means (not shown). . At the stop position of the cylindrical valve 5 shown in Fig. 1, the subchamber 4 and the exhaust port 3 communicate with each other, so the volume of the exhaust pipe is expanded and the blow-out phenomenon of fresh air is prevented mainly in the low and medium speed range. In addition, the plate 6 protrudes into the exhaust port 3 by the interlocking means 8 consisting of the rack 6c and the pinion 5b, and the upper edge 3b of the cylinder side opening 3a is secured.
Since the engine is lowered by H, at the same time, suitable exhaust timing for gas exchange is ensured in the low and medium rotational speed ranges.

On the other hand, when the two-stroke engine 2 reaches a predetermined high rotation speed range, the cylindrical valve 5 is instantaneously rotated clockwise from the initial position shown in FIG. 1 by the driving means and stopped at the position shown in FIG. 4. do.

According to the stop position of the cylindrical valve 5 shown in Fig. 4, the space between the subchamber 4 and the exhaust port 3 is closed and the exhaust pipe volume is reduced, so fresh air is not blown out mainly in the high rotation speed range. The exhaust pressure pulsating pressure suitable for preventing this phenomenon is ensured, and the plate 6 is moved upward by the interlocking means 8 to raise the position of the upper edge 3b of the cylinder opening by an amount H, so that at the same time high rotation is achieved. Exhaust timing for suitable gas exchange can be ensured within several ranges.

〔Effect of the invention〕

This invention includes a cylindrical valve that changes exhaust pipe volume;
The plate that changes the exhaust timing is linked via an interlocking means to ensure the exhaust pipe volume and exhaust timing suitable for each rotation speed range, so it can be used over a wide range from low rotation speeds to high rotation speeds. It is possible to smoothly improve the output of a 2-cycle engine in the rotation speed range. Also,
Since the interlocking means is composed of a rack formed on the back of the plate and a pinion formed on the circumferential surface of the cylindrical valve that meshes with this rack, the operation of the exhaust control device is reliable and the structure is Since it is simple and easy to attract, exhaust control tiD devices can be provided at low cost.

[Brief explanation of the drawing]

FIG. 1 shows a vehicle equipped with an exhaust control device according to the present invention.
Fig. 2 is a conceptual perspective view of the main parts of Fig. 1, Fig. 3 is a cross-sectional view of the main parts as seen from A in Fig. 1, and Fig. 4 shows the exhaust control according to the present invention. 1. Exhaust control device, 2. 2-stroke engine,
3...Exhaust port, 3a...Cylinder frontage, 3b...Cylinder side mouth part upper edge, 3c...Top wall, 4...Subchamber, 5...Cylindrical valve, 5b
...Pinion, 6...Plate, 6a...Bottom surface,
6b...Back, 6C...Rack, 7...Cylinder block.

Claims (1)

[Claims] a subchamber communicating with an exhaust port; and a subchamber disposed between the subchamber and the exhaust port,
In the exhaust control device for a two-stroke engine, which includes a cylindrical valve that opens and closes between the subchamber and the exhaust port, a hole is bored from inside the subchamber toward the upper wall of the exhaust port immediately after the cylinder side opening. and a plate whose lower surface forms the upper wall of the exhaust port is slidably disposed in the hole, a rack on the back surface of the plate, and a pinion that meshes with the rack on the circumferential surface of the cylindrical valve. , and when the cylindrical valve is rotated to widen the space between the subchamber and the exhaust port in a low rotational speed range of the engine, the cylindrical valve opens the lower surface of the plate. The upper edge position of the cylinder side opening of the exhaust port is lowered by protruding into the exhaust port, and the exhaust timing is set late, and the cylindrical valve is rotated in the high rotational speed range of the engine to lower the upper edge position of the cylinder side opening of the exhaust port. When the space between the chamber and the exhaust port is closed, the lower surface of the plate is caused to escape from the exhaust port by the cylindrical valve to raise the position of the upper edge of the cylinder side opening of the exhaust port, thereby adjusting the exhaust timing. An exhaust control device for a two-stroke engine, characterized in that it can be set quickly.