JPS62243923A - Exhaust controller of two cycle engine - Google Patents

Abstract

PURPOSE:To make compact the entity by providing a power chamber as a volume chamber for communicating through a gate valve with an exhaust port while providing an actuator such as an exhaust port open/close timing control valve in said power chamber. CONSTITUTION:A power chamber 8 is communicated through a gate valve 11 with an exhaust port 7 and opened/closed according to the operating condition of engine so as to improve the scavenging efficiency through proper pulsating exhaust effect. An actuator for an exhaust port open/close timing control valve 13 which opens/closes the upper edge section of an opening 5 of the exhaust port according to the operating condition of engine is constructed in the power chamber 8. Furthermore, a coupling section with a rotary shaft, a lever 16 and a rod 14 is also arranged. Since an actuator is arranged in the power chamber, the space can be utilized effectively.

Description

Detailed Description of the Invention 3. Full description of the invention (objective of the invention) (Field of industrial application) This invention is a two-stroke engine that is installed in the exhaust system in order to improve the output from low speed to high speed. exhaust flil
Regarding J III @Oki.

(Prior art) In a two-stroke engine, the piston descends due to the explosion of fuel, and in the process opens into the cylinder.The exhaust port, which had been closed by the piston, opens as the piston descends, and subsequently, the scavenging port opens in the same way. By opening, combustion gas is exhausted, but fresh air, which has been primarily compressed in the crankcase, flows into the cylinder (scavenging). During that time, the piston reverses itself from bottom dead center and rises, closes the scavenging port, then the exhaust port, compresses the fresh air that has flowed in, and ignites and explodes, repeating the process. However, since the scavenging is performed with the exhaust port open, there is a phenomenon in which the fresh air that has flowed in flows through the exhaust port, which affects the engine output.

The above-mentioned blowout phenomenon can be prevented by using exhaust pulsation. That is, if the timing is adjusted so that the exhaust pressure pulsates in the exhaust pipe and the exhaust port becomes a positive pressure during blow-through, blow-through can be suppressed and the filling rate can be improved. In order to match the above-mentioned timing from low speed to high speed of engine rotation, it is necessary to adjust the frequency of exhaust pulsation. A power chamber is one such means. The power chamber is an interference chamber with an appropriate volume that communicates with the exhaust passage through an opening/closing valve, and the opening/closing degree of this opening/closing valve is changed in response to the engine operating status, thereby controlling the frequency of exhaust pulsation. is adjusted for interference.

Additionally, in order to prevent blow-out during idling or low-speed operation where it is difficult to utilize exhaust pulsation, there is a system in which the exhaust passage is narrowed by an exhaust valve interposed in the exhaust passage. During,
At high speeds, the exhaust valve opens. Therefore, the exhaust valve is controlled according to the engine operating state.

On the other hand, in the atrium, in order to improve the filling of fresh air by scavenging, it is necessary to set an appropriate time difference between exhaust and scavenging, and at high rotation speeds, the piston descends faster and the time difference increases. Since the engine speed becomes shorter, the exhaust timing must be advanced, and conversely, the exhaust timing must be delayed at low rotation speeds. For this reason, some exhaust timing valves are attached to the upper edge of the exhaust port, and the height of the upper edge of the exhaust port is adjusted according to the engine speed to match the exhaust timing to the engine speed.

As described above, the two-cycle exhaust control is provided with a power chamber opening 1r1 valve, an exhaust valve, an exhaust timing valve, etc., and each valve is controlled via a drive mechanism according to required conditions.

Therefore, some of these drive mechanisms are arranged in the exhaust passage layer of the engine cylinder block.

For example, as shown in FIGS. 3 and 4, a power chamber e integrally formed with a cylinder block C and a cylinder head d is provided above the exhaust passage opening into the cylinder a, and the power chamber e and the exhaust passage A rotary type opening m valve Q is interposed and provided in the communication path f that communicates the two. On the other hand, a valve operating chamber i is recessed in the upper wall of the exhaust passage immediately behind the exhaust port, and an exhaust timing valve j that fills this portion is fitted so as to be vertically slidable. The operating rod fixed to the exhaust timing valve j extends downward through the exhaust passage, and its lower end protrudes outward, and an operating rod fixed to the swing shaft m is attached to the engaging pin l protruding from the lower end. Forked portion 0 at the tip of lever n is engaged. A driven pulley p is fixed to a swing shaft m, and a driven pulley p is rotated in relation to the engine speed by a wire connected thereto, and the exhaust timing valve j
The exhaust timing is controlled by raising and lowering the

In this way, the drive mechanisms for each valve exist in a crowded state in the exhaust passage, which not only makes space cramped and gets in the way, but also exposes them to the outside in motorcycle engines. Because of this, water and debris can be exposed to large amounts, causing problems. For this reason, a mechanism 9Js may be provided for sealing, which poses the problem of further complicating the structure.

(Problems to be Solved by the Invention) The conventional arrangement of drive mechanisms such as the power chamber rM valve closing, exhaust valve, or exhaust timing valve provided in the two-stroke engine exhaust system does not require space. In view of the fact that there are many structural problems, it is an object of the present invention to solve these problems and to provide an exhaust control device for a two-stroke engine that makes effective use of space.

[Structure of the invention]

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a power chamber with an appropriate volume that communicates with the exhaust passage through an on-off valve that opens in response to the operating state of the engine. In addition, a part of the drive mechanism such as an exhaust timing valve attached to the exhaust port, an exhaust valve that adjusts the opening of the exhaust passage, or the power chamber 1mrll valve described above is arranged in a sealed state in the power chamber. be done.

(Function) With the above configuration, the operating mechanisms of various valves are organized in the power chamber, and water and debris are shut off to ensure precision maintenance without providing a special mechanism chamber. Since the power chamber requires a relatively large volume, it is easy to accommodate part of the drive mechanism, and the drive mechanism is extremely small compared to its volume and has a small operating range, so Even if something exists, there is no problem with the function of the power chamber itself.

(Example) DESCRIPTION OF THE PREFERRED EMBODIMENTS The drawings showing embodiments of the present invention will be explained below.

The figures show a two-stroke engine equipped with a power chamber and an exhaust timing valve, with FIG. 1 being a longitudinal side view and FIG. 2 being a longitudinal front view.

The cylinder 1 is constructed on the inner surface of a sleeve 3 fitted into a cylinder block 2, and a cylinder head 4 is stacked on the upper surface of the cylinder block 2. The cylinder 1 has an exhaust port 5 and a scavenging port 6, which are opened and closed by the vertical movement of the piston. 7 is an exhaust passage continuous with the exhaust port 5, and a lower chamber Ba is formed in the cylinder block 2 above the exhaust passage 7.
The power chamber 8 is constructed by overlapping an intermediate chamber 8b formed in the cylinder head 4 and an upper chamber 8C formed in the cover 9. A communication passage 10 communicates between the power chamber lower chamber 8a and the exhaust passage 7, and the opening degree is controlled by a rotary nm valve 11 interposed therein. The power chamber 8 has the role of an interference chamber, which interferes with the exhaust air pulsation in which the exhaust system is a single pipe, and changes the pulsation frequency depending on the opening degree of the opening m valve 11. Open/close valve 1
1 is controlled according to the engine speed, and in the rotation range from low speed to high speed, positive pressure is applied to the vicinity of the exhaust port 5 in a well-timed manner to prevent scavenging air from blowing through.

Next, a valve operating chamber 12 is recessed in the upper wall of the exhaust passage 7 immediately behind the exhaust port 5, and an exhaust timing valve 13 is fitted into the chamber so as to be vertically slidable. Exhaust timing valve 13
The lower end of the actuating rod 14 is fixed to the actuating rod 14.
passes through the cylinder block 2 and cylinder head 4, and an upper end 14a protrudes into the power chamber 8. A swing shaft 15 is horizontally suspended within the power chamber 8, and a fork 17 at the tip of a swing lever 16 fixed to one end engages with a pin 18 at the upper end 14a of the operating rod. The swing shaft 15 projects outside the power chamber 8, and a driven pulley 19 is fixed thereto. A drive mechanism (not shown) such as a centrifugal force related to the engine speed rotates the swing shaft 15 forward and backward through the driven pulley 19, and the swing lever 16 swings up and down to move the actuating rod 14. By moving it up and down, the exhaust timing valve 13 moves up and down in accordance with the engine speed. At low speeds, it goes down to delay the exhaust timing, and at high speeds, it goes up to speed up the exhaust timing.

As described above, of the drive mechanism that controls the exhaust timing valve 13 up and down, the upper end of the operating rod 14, the swing shaft 15, the swing lever 16, etc. are housed in the power chamber 8, so that the power chamber Due to its nature, it is naturally sealed, preventing damage from water, dust, and dirt. At the same time, space can be used effectively and the appearance can be organized. The power chamber 8 is constituted by a cover 9 whose upper half can be divided, which facilitates processing and maintenance of the device.

The original function of the power chamber 8 is not affected at all.

〔Effect of the invention〕

The two-stroke engine exhaust control device according to the present invention includes:
As mentioned above, part of the drive mechanism for the exhaust timing valve, exhaust valve, or power chamber opening/closing valve is housed and sealed inside the power chamber, eliminating the need for individual special mechanisms to simplify the structure and save space. This has the effect of maintaining the precision of various valve controls, improving durability, and reducing costs.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional side view of a two-stroke engine showing an embodiment of the present invention, FIG. 2 is a longitudinal sectional front view of the same, and FIG. 3 is a longitudinal sectional side view of a two-stroke engine showing a conventional exhaust timing valve drive mechanism. FIG. 4 is a plan view taken along the line AA in FIG. 3. 1...Cylinder, 2...Cylinder block, 4...
・Cylinder head, 5...Exhaust port, 7...Exhaust passage, 8...Power chamber, 11...Opening/closing valve, 1
2... Valve operating chamber, 13... Exhaust timing valve, 14... Operating rod, 15... Swing shaft, 16...
... Swing lever, 19... Driven pulley. Figure 1 Figure 2

Claims (1)

[Claims] A power chamber with an appropriate volume is provided in the middle of the exhaust passage and communicates with it via an on-off valve that opens and closes in response to the operating state of the engine. 1. An exhaust gas control device for a two-stroke engine, characterized in that a part of a drive mechanism such as an exhaust valve for adjusting temperature or the above-mentioned power chamber opening/closing valve is disposed.