JPH0656103B2 - Exhaust valve control method for two-cycle engine - Google Patents

Description

The present invention relates to a two-cycle engine having an auxiliary exhaust valve or an exhaust passage extending from a main exhaust port (main exhaust passage) having an exhaust control valve. The present invention relates to a method for controlling the auxiliary exhaust valve or the exhaust control valve.

(Prior Art) In a two-cycle engine, for example, a two-cycle engine mounted on a motorcycle or the like, a high-speed rotation is achieved by reducing the passage cross-sectional area of the exhaust passage of the engine body at low speed rotation and at high speed rotation. There is a vehicle equipped with an exhaust control device (for example, Japanese Patent Laid-Open No. 60-249614) for improving the output during rotation. On the other hand, the present applicant has also proposed an exhaust control device that should achieve the same purpose (Japanese Patent Application No. 62-105604). That is, this exhaust control device includes an auxiliary exhaust port provided separately from the main exhaust port in the cylinder, and an exhaust passage (a passage connecting the main exhaust port and the exhaust pipe; a main exhaust passage for distinguishing from the auxiliary exhaust passage). ) Is connected to an auxiliary exhaust passage that connects and disconnects this passage, and this auxiliary exhaust valve is opened and closed by a drive motor depending on the engine speed range.
It is intended to change the passage cross-sectional area of the auxiliary exhaust passage and thus the entire exhaust passage.

Specifically, as shown in FIG. 7 (a diagram showing the relationship between the opening / closing timing of the auxiliary exhaust valve and the rotational speed), a specific rotational speed R ₀ (engine rotational speed at which the auxiliary exhaust valve starts operating) (Hereinafter referred to as "specific rotation speed"), the auxiliary exhaust valve is fully opened by the drive motor to increase the passage cross-sectional area of the entire exhaust passage and improve the output in the high speed rotation range. ing.

A typical example of this kind of auxiliary exhaust valve is a cylindrical valve 2 having a through hole in a part as shown in FIG. 2 (circular shape having a through hole in FIG. 2). In some cases, the auxiliary exhaust passage 1d is opened and closed to change the passage cross-sectional area of the exhaust passage. Also, as changing the passage cross-sectional area of the main exhaust passage itself extending from the main exhaust port,
The passage cross-sectional area of the main exhaust passage 1c is changed by rotating a columnar exhaust control valve 2 '(a circular shape in the side sectional view of Fig. 8) having a notch in a part as shown in Fig. 8. Or a columnar shape having axial notches as shown in FIGS. 8 (a) and 8 (b) (side view of FIG. 9).
(a) A circular exhaust control valve 2'shown in the direction of the arrow I'-I 'is rotated to freely project into the main exhaust passage 1c' to change the passage cross-sectional area, or the tenth An exhaust adjustment valve in a flywheel shape which is rotatably supported by a shaft 20 on the exhaust pipe (not shown) side of the main exhaust passage 1c as shown in FIGS. 2 '
A free end 2a 'of the drive shaft 21 is moved up and down to change its passage cross-sectional area, or a plate-like exhaust gas is introduced into the main exhaust passage 1c by a gear mechanism 22 as shown in FIG. There is one in which the adjusting valve 2'is made to project freely so that the cross-sectional area of the passage can be changed.

(Problems to be Solved by the Invention) However, in the exhaust control device having the auxiliary exhaust passage, the auxiliary exhaust passage is fully opened or the main exhaust passage has an exhaust adjusting valve. If a control state in which the exhaust passage is fully opened is continued, the engine output will exceed a predetermined horsepower (limit horsepower).

On the other hand, in the above-mentioned two-cycle engine, since a mixed fuel of oil and gasoline is used, carbon is likely to adhere to the auxiliary exhaust valve or the exhaust control valve, which may cause malfunction of the auxiliary exhaust valve or the exhaust control valve. There is.

(Means for Solving the Problem) Therefore, in the exhaust valve control method according to the present invention, the auxiliary exhaust valve is provided in the auxiliary exhaust passage communicating with the auxiliary exhaust port, or the passage sectional area is adjusted in the main exhaust passage. In a two-cycle engine equipped with an exhaust control valve, the opening degree (passage cross-sectional area) of the auxiliary exhaust valve is limited when the engine speed is a specific rotation speed or higher, or the passage cross-sectional area of the main exhaust passage is restricted. If the engine becomes a certain acceleration or deceleration or more (the acceleration may be detected directly by the acceleration or by the movement of the throttle), the auxiliary exhaust valve or The exhaust control valve is made to oscillate, while the auxiliary exhaust valve or the exhaust control valve is operated when the engine falls below the certain acceleration. Stop swinging of the probe, characterized by being made to be a or a predetermined cross-sectional area to a predetermined degree.

(Operation) In the above configuration, when the engine speed is equal to or higher than the specific speed, the auxiliary exhaust valve restricts the opening degree of the auxiliary exhaust passage, or the exhaust control valve restricts the passage sectional area of the main exhaust passage to improve the exhaust efficiency. To reduce the engine output within a predetermined range. When the engine is in an acceleration or deceleration state above a certain level, the auxiliary exhaust valve or the exhaust control valve is swung to remove the carbon adhering to them.

When the engine acceleration falls below a certain value, the swing of the auxiliary exhaust valve or the exhaust control valve is stopped to reduce the load on the valve drive system.

(Example) Hereinafter, one example of the present invention will be described with reference to the drawings.

FIG. 1 is a side sectional view of a two-cycle engine equipped with an auxiliary exhaust port, an auxiliary exhaust passage, and an auxiliary exhaust valve, FIG. 2 is a sectional view taken along the line II of FIG. 1, and FIG. 3 is an auxiliary exhaust valve for the engine. Drawing which shows the schematic structure of the engine which shows the state in which the drive motor was attached, FIG. 4 is a block diagram which shows the structure of the igniter (control device) which controls the auxiliary | assistant exhaust valve of an engine, and a connection with the to-be-controlled object. .

As shown in FIG. 1 or 2, a main exhaust port 1a and an auxiliary exhaust port 1b are formed on the peripheral wall surface of the cylinder 1.

The main exhaust port 1a is connected to an exhaust pipe (not shown) by the main exhaust passage 1c. The auxiliary exhaust port 1b is connected to the main exhaust passage 1c by an auxiliary exhaust passage 1d. In the auxiliary exhaust passage 1d, an auxiliary exhaust valve 2 for limiting the opening of this passage is provided.
Is provided.

As shown in FIG. 3, the auxiliary exhaust valve 2 is provided with a drive motor 3 via a transmission mechanism such as a wiper 11 and a reel 12.
Is mechanically coupled to the rotary shaft of the drive motor 3, and by the rotation (drive) of the rotary shaft of the drive motor 3, the auxiliary exhaust valve 2 shown in FIGS. 1 and 2 is switched from fully open to fully closed or an intermediate opening. You can do it. A potentiometer 6 for detecting a rotation angle is attached to a rotation shaft (not shown) of the drive motor 3.

The drive motor 3 and the potentiometer 6 are electrically connected to the igniter 4. This igniter 4
As shown in FIG. 4, it is connected to a sensor 5 attached to a generator (actually disposed around the circumference of the crankshaft) 7 so that the engine speed R _n can be detected. Then, the acceleration α of the engine at that time is calculated. The drive motor 3 is controlled by the igniter 4, and the auxiliary exhaust valve 2 (see FIGS. 1 and 2) is opened and closed by the rotation of the drive motor 3. The opening / closing (including the intermediate opening) operation of the auxiliary exhaust valve 2 is confirmed by the potentiometer 6.

Next, the control method of the present invention will be described. When the fully opened state of the auxiliary exhaust valve 2 as shown in FIG. 2 is continued, the engine output becomes equal to or higher than a predetermined horsepower (limit horsepower).
As shown in FIG. 5, when the valve port (through hole) 2b of the auxiliary exhaust valve 2 has the same size as that of the auxiliary exhaust passage 1d as in the conventional case, the auxiliary exhaust valve 2 has a specific rotational speed or more. The opening of, for example, fully open 3/4 opening,
That is, the opening degree of the auxiliary exhaust passage 1d is limited to an intermediate opening degree of about 75 ° (90 ° when fully opened) (two-dot chain line in FIG. 7) to reduce the exhaust efficiency. This keeps the engine output within the limit.

By the way, when such control of the auxiliary exhaust valve 2 is performed, the wall surface of the auxiliary exhaust passage 1d and the main body of the auxiliary exhaust valve 2 are
Carbon C may be attached and deposited at the intersection with 2a. Therefore, in order to prevent this, the auxiliary exhaust valve 2 is swung slightly to remove the attached carbon using the corners of the wall surface of the auxiliary exhaust passage 1d. The swinging of the auxiliary exhaust valve 2 as described above is performed when the engine is in an accelerating state, and the acceleration is a certain value (for example,
Control is performed only when the engine speed is 8000 rpm or higher and the acceleration α is 300 rpm / sec or higher). The same control is performed during deceleration.

It should be noted that when the acceleration is equal to or lower than a certain value, the rocking operation is not performed, and the number of rocking operations is appropriately maintained to reduce the load on the valve drive system.

FIG. 6 shows another embodiment. That is, in the above-described embodiment, the opening of the auxiliary exhaust valve 2 is set to an intermediate opening of about 3/4 of the full opening in order to narrow the opening of the auxiliary exhaust valve 2 a little less than the full opening. In the example, the valve port (through hole) 2b 'of the auxiliary exhaust valve 2 is formed to be narrower than the auxiliary exhaust passage 1d in advance, that is, the passage cross-sectional area is made small and limited. Therefore, set this auxiliary exhaust valve 2'to 90
Exhaust resistance is added as a fully opened state (solid line in FIG. 7) with a degree of opening to reduce exhaust efficiency. This limits the engine output to within a predetermined horsepower. Also in this case, since carbon C'is easily attached and deposited at the intersection of the main body 2a 'of the auxiliary exhaust valve 2'and the wall surface of the auxiliary exhaust passage 1d,
The auxiliary exhaust valve 2 is swung to remove it.

Further, the above-mentioned embodiment relates to a two-cycle engine equipped with an auxiliary exhaust valve, but the control of the auxiliary exhaust valve is performed by referring to FIG. 8, FIG. 9 (a), (b), and FIG.
(a), (b), as shown in FIG. 11, in the control of the exhaust control valve of the two-cycle engine which is configured to have the exhaust control valve 2'in the main exhaust passage to control the exhaust. Can be similarly applied. That is, when the engine speed is equal to or higher than the specific speed, the exhaust control valve restricts the passage cross-sectional area to reduce the exhaust efficiency and keep the engine within the predetermined output range. Further, when the engine becomes equal to or higher than a certain acceleration or deceleration, the exhaust control valve is swung to remove the carbon adhering to the exhaust control valve. On the other hand, when the engine falls below the certain acceleration, the swing of the exhaust control valve is stopped and a predetermined cross-sectional area of the exhaust passage is provided to reduce exhaust efficiency and reduce the burden on the valve drive system. Reduce.

Incidentally, in the above-mentioned embodiment, the "oscillation" of the auxiliary exhaust valve or the exhaust adjustment valve means "open" when the oscillation signal is first input, and "closes" when the oscillation signal is not output. It is preferable that the rocking is performed at different timings. However, the opening / closing operation may be performed at an appropriate time interval while the swing signal is being output.

(Advantages of the Invention) As described above, according to the present invention, the opening degree of the auxiliary exhaust passage is limited by the auxiliary exhaust valve at a specific engine speed or higher.
Alternatively, since the passage sectional area of the main exhaust passage is limited by the exhaust control valve, it is possible to quickly and smoothly limit the engine output within the predetermined horsepower.

In addition, the drawback of the carbon of the two-cycle engine, which tends to adhere, has been improved by swinging the auxiliary exhaust valve or the exhaust adjusting valve to remove the carbon when acceleration or deceleration is above a certain level. The malfunction of the exhaust valve can be avoided.

As a result, the engine output control by the auxiliary exhaust valve or the exhaust control valve can be improved.

[Brief description of drawings]

FIG. 1 is a side sectional view of an upper portion of a cylinder of a two-cycle engine equipped with an auxiliary exhaust port, an auxiliary exhaust passage, and an auxiliary exhaust valve, FIG. 2 is a sectional view taken along the line II of FIG. 1, and FIG. FIG. 4 is a block diagram showing a schematic configuration of an engine showing a state in which an exhaust valve driving motor is attached, FIG. 4 is a block diagram showing a configuration of an igniter for controlling an auxiliary exhaust valve of the engine, and FIG. 5 is a control of the auxiliary exhaust valve. FIG. 6 is a drawing for explaining the method, FIG. 6 is a drawing for explaining another embodiment of the control method, and FIG. 7 is a view showing the relationship between the opening / closing timing of the auxiliary exhaust valve and the rotational speed, FIG. Is a side sectional view of the upper portion of the cylinder of a two-cycle engine equipped with an exhaust control valve, FIG. 9 (a) is a side sectional view of a two-cycle engine equipped with another type of exhaust control valve, and FIG. 9 (b) is Fig. 9
FIG. 10A is a sectional view taken along the line I′-I ′ of FIG. 10, and FIG. 10A is a side sectional view of a two-cycle engine equipped with another type of exhaust control valve.
Figure (b) is a view taken along the arrow II'-II 'in Figure 10 (a), and Figure 11 is a side sectional view of the upper portion of the cylinder of a two-cycle engine equipped with an exhaust control valve. 1 ... Cylinder, 1a ... Main exhaust port, 1b ... Auxiliary exhaust port, 1c ... Main exhaust passage, 1d ... Auxiliary exhaust passage, 2 ...
... Auxiliary exhaust valve, 2 '... Exhaust control valve.

Claims (2)

[Claims] 1. A cylinder is provided with a main exhaust port and an auxiliary exhaust port, an auxiliary exhaust passage communicating with the auxiliary exhaust port is connected to an exhaust passage communicating with the main exhaust port, and the auxiliary exhaust valve is provided in the auxiliary exhaust passage. A two-cycle engine in which an engine rotation speed is equal to or higher than a specific rotation speed and the opening degree of the auxiliary exhaust passage is limited by the auxiliary exhaust valve, or the passage cross-sectional area thereof is limited. Is oscillating the auxiliary exhaust valve when the acceleration is equal to or higher than a constant acceleration or deceleration, while stopping the oscillation of the auxiliary exhaust valve when the engine is lower than the constant acceleration. A method for controlling an auxiliary exhaust valve in a two-cycle engine, characterized in that a predetermined opening is provided. 2. A two-cycle engine having a main exhaust passage extending from a main exhaust port of a cylinder and an exhaust control valve for changing a passage cross-sectional area of the main exhaust passage, wherein the engine speed is equal to or higher than a specific speed. The size of the passage cross-sectional area of the exhaust control valve is limited so that the exhaust control valve is oscillated when the engine reaches a certain acceleration or deceleration, while the engine controls A method for controlling an exhaust control valve in a two-cycle engine, characterized in that when the acceleration falls below a certain acceleration, the swing of the exhaust control valve is stopped so that a predetermined passage cross-sectional area is achieved.