JPH0636280Y2 - Exhaust control device for 2-cycle engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to an exhaust control device for a two-cycle engine, and more particularly to an exhaust control device in which an exhaust port of the engine is provided with a control valve for controlling exhaust timing. At
The present invention relates to an exhaust control device for a two-cycle engine having a function of removing carbon attached to the control valve.

(Prior Art) In a motorcycle, an automobile, etc. (hereinafter, referred to as a vehicle) equipped with a two-cycle engine, a control valve (hereinafter, referred to as a vehicle) for varying an exhaust timing to an exhaust port of the engine.
A technique has been proposed in which an exhaust valve is provided) and the exhaust valve is controlled according to the engine speed or the like to improve the output of the engine.

Such techniques are described in, for example, Japanese Patent Application Laid-Open No. 61-4820 and Japanese Patent Application No. 63-239787.

FIG. 5 shows an example of the relationship between the target opening degree of the exhaust valve and the engine speed.

By the way, carbon contained in the exhaust gas adheres to such an exhaust valve. However, if the amount of carbon adhered is too large, good operation of the exhaust valve is hindered.

Therefore, Japanese Patent Application Laid-Open No. 54-158514 discloses a technique in which the exhaust valve is forcibly fully opened when the ignition switch is turned on to remove carbon adhering to the exhaust valve.

(Problems to be Solved by the Invention) The above-described conventional technique has the following problems.

As described in Japanese Patent Laid-Open No. 54-158514, if the exhaust valve is once fully opened when the ignition switch is turned on, the exhaust valve cannot be driven when the battery voltage is low. There are cases.

The present invention has been made to solve the above-described problems, and an object thereof is to provide an exhaust control device for a two-cycle engine that can reliably remove carbon from an exhaust valve even when the battery voltage is low. To provide.

(Means and Actions for Solving the Problem) In order to solve the above-mentioned problems, the present invention is directed to a time point when the engine speed becomes equal to or higher than a predetermined speed (set speed) higher than an idle speed. The feature is that the exhaust valve is temporarily forced to rotate.

When the engine is rotating by itself, the exhaust valve is reliably rotated by the power generation of the AC generator even if the battery voltage is low, whereby carbon is removed.

(Example) Hereinafter, the present invention will be described in detail with reference to the drawings.

In the figure, an exhaust port 3 which is opened and closed by a piston 2 slidably arranged in the cylinder 1 is formed on the inner surface of a cylinder 1 of a two-cycle engine 43 mounted on a vehicle. An exhaust valve 4 is provided above the exhaust port to control the opening / closing timing of the valve 3. The exhaust valve 4 changes the exhaust timing of the two-cycle engine according to the engine speed. The exhaust valve 4 may be controlled based on not only the engine speed but also data such as throttle opening.

Further, the exhaust pipe 5 connected to the exhaust port 3 has the first pipe portion 5a.
And a second truncated cone-shaped second pipe portion 5b having a large-diameter end connected to the downstream end of the first pipe portion 5a.
An expansion chamber 6 is provided in the tube portion 5b.

A tail pipe 23 is fitted and fixed to a small-diameter end, that is, a downstream end of the second pipe portion 5b of the exhaust pipe 5, and an outer end of the tail pipe 23 is connected to the silencer 8. In the second pipe portion 5b, a truncated cone-shaped reflecting pipe 24 is arranged as a control operating means for reflecting the positive pressure wave generated by the exhaust toward the exhaust port 3. The reflecting pipe 24 changes the exhaust pipe length of the two-cycle engine to change its exhaust characteristic.

This reflecting tube 24 has a second end with the large diameter end facing the first tube portion 5a.
Servo motor 26, which is arranged in tube portion 5b and whose operation is controlled by electronic control device 20, is
They are connected via the electric mechanism 27. That is, in the second pipe portion 5b, the drive shaft 29 is rotatably supported by the bearing portion (not shown) provided on the upper outer surface of the large diameter end of the second pipe portion 5b.
29 and a driven shaft 30 provided on the large-diameter end of the reflecting tube 24 are connected by a connecting rod 31, and the electric mechanism 27 is connected to the drive shaft 29.

As a result, the connecting rod 31 is driven in response to driving the drive shaft 29.
Oscillates, which causes the reflection tube 24 to oscillate along the tail pipe 23.

A potentiometer 34 is attached to the servomotor 26. The potentiometer 34 detects the position of the reflection tube 24, that is, the rotation amount of the drive shaft 24, and the detected amount is input to the electronic control unit 20.

The exhaust valve 4 provided in the exhaust port 3 is fixed to a drive shaft 12 rotatably arranged in the cylinder 1.
The drive shaft 12 is connected to a servo motor 14 as a drive source via a transmission mechanism 13 including a pulley and an electric belt. Further, the servomotor 14 is provided with a potentiometer 15 for detecting the operation amount of the servomotor 14, that is, the opening degree of the exhaust valve 4, and the detected amount is also the electronic control unit 20.
Entered in.

Further, the electronic control unit 20 includes an engine speed sensor.
Output signals (engine speed Ne and throttle opening θth) of the throttle valve 21 and the throttle opening sensor 22 are input.

The electronic control unit 20 is provided with a microcomputer including a CPU, a ROM, a RAM, an input / output interface and a bus connecting them, and as will be described later,
The opening of the exhaust valve 4 is controlled and the position of the reflection tube 24 is controlled. The electronic control unit 20 includes a servo motor 14
And 26 drivers.

FIG. 3 is a side view showing an essential part of an example of a motorcycle equipped with an exhaust control device for a two-cycle engine as shown in FIG. In FIG. 3, the same reference numerals as those in FIG.
Represents the same or equivalent part. Further, in FIG. 3, the exhaust valve 4 is arranged in the two-cycle engine 43 and is not shown.

In FIG. 3, reference numeral 41 is a frame body, 42 is a seat rail, 44 is a radiator, 45 is a front fork, 46 is a front fender, 47 is a front wheel, 48 is a swing arm, 49 is a rear fender, 50 is a rear wheel, and 65 is a rear wheel.
Is a fuel tank, 67 is a cowl, 68 is a side cover, and
70 is a battery.

The change pedal 55 having the step 71A is attached to the step plate 71L, and the step plate 71L is
It is fixed to a back plate 41A formed at the rear of the frame body 41.

A reflection tube 24 (Fig. 2) arranged inside the rear end of the exhaust pipe 5.
A pulley 51L is attached to a drive shaft 29 that drives the.

On the rear fender 49 attached to the seat rail 42,
A pedestal 69B is attached, and the pedestal 69B has a servo motor.
26 are placed.

The pulley 51L is connected to a pulley 69A attached to the rotary shaft of the servo motor 26 by a control cable 53L.

The control cable 53L is composed of an outer wire and an inner wire slidably arranged in the outer wire. Both ends of the outer wire are fixed to the adjuster stopper 52L and the mount 69B by an adjuster, and the inner wire in the outer wire is connected to the pulley 51L and the pulley 69A by an appropriate method. The adjuster stopper 52L is
It is formed of metal, resin, or the like into a box shape, and a pulley 51L is housed in the adjuster stopper 52L.

When the servo motor 26 is rotated by the connection using the control cable 53L, the pulley 51L rotates, which causes the reflection tube 24 shown in FIG. 2 to slide back and forth.

As shown in FIG. 3, the control cable 53L passes through the back surface of the step plate 71L to which the step 71A is attached and the back surface (inside) of the back plate 41A formed at the rear of the frame body 41. There is. In other words, the control cable 53L is arranged so as to pass through the inside of the frame of the motorcycle. As a result, there is no risk of the control cable 53L getting caught on the foot of the passenger of the motorcycle.

The exhaust valve 4 shown in FIG. 2 also has the same structure.
It is connected to the servomotor 14.

Now, the operation of the electronic control unit 20 for removing the carbon attached to the exhaust valve 4 will be described.

FIG. 4 is a flowchart showing a control method of the exhaust valve 4 by the electronic control unit 20. This process is interrupted by the crank signal output according to the rotation of the crankshaft.

First, in step S1, the engine speed Ne is detected by a known method.

In step S2, it is determined whether or not the engine speed Ne is a predetermined speed equal to or higher than the idle speed, for example, 2000 [rpm] or higher.

If it is 2000 [rpm] or higher, it is determined in step S3 whether the timer flag is 0 or not. This timer flag will be described later with respect to step S9.

If the timer flag is 0, it is determined in step S4 whether or not the RC flag is 1. This RC flag will be described later regarding step S7.

If the RC flag is not 1, the timer in the electronic control unit 20 is started (started) in step S5.

When the RC flag is 1, or after the processing of step S5,
In step S6, the exhaust valve 4 is driven to the fully open state.

In step S7, the RC flag is set to 1.

In step S8, the time measured by the timer is 1
It is determined whether or not the time has exceeded the second. If 1 second or more has elapsed, the timer flag is set to 1 in step S9.
Is set to.

When the time measured by the timer has not elapsed for 1 second or more, or after the processing of step S9, the processing ends.

In step S2, the engine speed Ne is 2000 [rp
m] or more, it is determined, or the step S3
If it is determined that the timer flag is not 0 in step S10, normal control of the exhaust valve 4 is performed in step S10. This normal control is performed so that the opening degree of the exhaust valve 4 has a relationship with the engine speed Ne, for example, as shown in FIG.

As is clear from the above description, in this embodiment, the engine speed Ne starts after the engine is started.
At the time of 2000 [rpm] or more, the exhaust valve 4 is fully opened for 1 second, and the carbon adhering to the exhaust valve 4 is removed. And after that, the exhaust valve 4
Returns to the normal control state.

After the engine speed Ne falls below 2000 [rpm], it becomes 200 again.
Even when the speed becomes 0 [rpm] or more, the timer flag is set to 1, so that carbon is not removed.

The present inventor conducted an experiment in which the exhaust valve 4 was fully opened only once and the carbon was removed after the engine speed Ne became 2000 [rpm] or more after the operation of the engine was started, It has been found that if the carbon is removed only once in this manner, then the carbon is continuously removed by the operation of the exhaust valve 4 under the normal control, and the operation of the exhaust valve 4 has no bearing.

Of course, the carbon removal by the fully opening operation of the exhaust valve 4 may be performed not only once but also several times after the engine is started.

FIG. 1 is a functional block diagram of an embodiment of the present invention. In FIG. 1, the same reference numerals as those in FIG. 2 represent the same or equivalent parts.

In FIG. 1, a set engine speed storage means 102 is an engine speed Ne1 (hereinafter, a set engine speed N for determining whether or not the exhaust valve 4 is fully opened for carbon removal).
It is called e1. In the above example, the storage means is 2000 [rpm]). This set speed Ne1 is the engine speed detecting means 101.
The actual rotation speed Ne of the engine (hereinafter, simply referred to as engine rotation speed Ne) detected by the comparison means 10
Entered in 3.

The comparison means 103 includes an engine speed Ne and a set speed Ne1.
When the engine rotation speed Ne is equal to or higher than the set rotation speed Ne1, "1" is output to the inverter 104 and the timer 110. The output source of this inverter 104 is an OR gate 105.
Connected to one of the input terminals.

The timer flag storage means 109 stores the timer flag output from the timer 110. When the timer flag is stored, “1” is stored. When the timer flag is not stored, “0” is stored. Output to the other input terminal.

The normal control means 106 is energized when "1" is output from the OR gate 105, and stores the relationship between the target opening degree of the exhaust valve 4 and the engine speed Ne as shown in FIG. The map 107 and the engine speed Ne output from the engine speed detector 101 are used to output the opening signal of the exhaust valve 4 to the driver 108.

The driver 108 drives the servomotor 14, which causes
The exhaust valve 4 is set to a predetermined opening degree.

In FIG. 1, the illustration of the configuration of the opening control of the exhaust valve 4 by the feedback control using the potentiometer 15 is omitted.

The timer 110 is activated by “1” output from the comparison means 103 when the timer flag is not stored in the timer flag storage means 109. Then, the fully-open value storage means 111 is energized for the scheduled time (1 second in the above example), and the data (fully-open angle of the exhaust valve 4) stored in the fully-open value storage means 111 is output to the driver 108. .

The normal control means 106 sets the opening degree according to the engine speed Ne, but when data is output from the full-open value storage means 111, only the scheduled time is irrespective of the engine speed Ne. The opening degree of the exhaust valve 4 is fully opened.

When the engine is started, the timer flag storage means 109
Since the timer flag stored therein is reset, the timer 110 is started when the engine speed Ne first becomes equal to or higher than the set speed Ne1. In this case, the inverter 1
The output of 04 is “0”, and the timer flag storage means 109
Since the timer flag is not stored therein, the output signal of the timer flag storage means 109 is also "0". Therefore, in this case, the normal control means 106 is not energized.

As described above, the timer 110 activates the full-open value storage means 111 by its activation and outputs the data in the storage means 111 to the driver 108, but stops the activation when the scheduled time has elapsed. Then, the timer flag is output to the timer flag storage means 109. Then, the timer flag storage means 109 stores the timer flag.

Therefore, the timer 110, once started, is not started even when the engine speed Ne falls below the set speed Ne1 and becomes equal to or higher than the set speed Ne1 again, and is output from the timer flag storage means 109. By the "1" signal, the normal control means 106 continues to be energized.

FIG. 6 is a functional block diagram of another embodiment of the present invention.
6, the same reference numerals as those in FIGS. 1 and 2 represent the same or equivalent portions.

In FIG. 6, the switching means 113 normally connects the map 107 to the normal control means 106, but when the timer 110 is started, the full-open map 112 is normally opened for the scheduled time by the start of the timer 110.
Connect to. The full-open map 112 stores full-open angle data such that the exhaust valve 4 is fully open at any engine speed.

Further, the normal control means 106 is always energized.

Also in this example, similar to the embodiment shown in FIG.
Carbon removal can be performed.

The electronic control unit 20 controls the reflection tube 24 shown in FIG. 2 and the ignition device in addition to the control of the exhaust valve 4.
It controls a fuel injection device, an automatic transmission, etc. (none of which is shown).

FIG. 7 is a vertical sectional view of the electronic control unit 20.

In FIG. 7, various elements 203 such as a microcomputer for realizing the function of the electronic control unit 20 are arranged on a circuit board 206. And these are the mounting holes 2
A case 201 having 01A is half-molded with resin. That is, the circuit board 206 and the element 203
Only the mounting part of the mold 204 is molded. The tip portion of the element 203 is exposed.

The lid 202 having the drain hole 202A is attached to the case 201 by a known method.

The electronic control unit 20 configured in this way is attached to the rear fender 49 (Fig. 3) using the bolts 205 and the like so that the case 201 is located above (see Fig. 8).

As a result, even if the inside of the electronic control unit 20 is flooded due to rain or the like,
Since water collects on the lid 202 side, it hardly affects the element 203, the circuit board 206, etc., and in this case,
Water is discharged through the drain hole 202A.

(Effect of the Invention) As is apparent from the above description, according to the present invention, the exhaust valve can be reliably rotated even when the battery voltage is low,
Carbon is removed. Therefore, good operation of the exhaust valve is always guaranteed.

[Brief description of drawings]

FIG. 1 is a functional block diagram of an embodiment of the present invention. FIG. 2 is a block diagram of an embodiment of the present invention. FIG. 3 is a side view showing an essential part of an example of a motorcycle equipped with an exhaust control device for a two-cycle engine as shown in FIG. FIG. 4 is a flowchart showing a method of controlling the exhaust valve by the electronic control unit. FIG. 5 is a graph showing an example of the relationship between the target opening of the exhaust valve and the engine speed. FIG. 6 is a functional block diagram of another embodiment of the present invention. FIG. 7 is a vertical sectional view of an example of the electronic control unit. FIG. 8 is a diagram showing how the electronic control unit is attached. 4 ... Exhaust valve, 14 ... Servo motor, 20 ... Electronic control device, 43 ... Two-cycle engine, 101 ... Engine speed detection means, 102 ... Set speed storage means, 103 ... Comparison means, 10
6 ... Normal control means, 107 ... Map, 108 ... Driver, 109 ...
Timer flag storage means, 110 ... Timer, 111 ... Full open value storage means, 112 ... Full open map, 113 ... Switching means

Claims (1)

[Scope of utility model registration request] 1. An exhaust valve provided in an exhaust port of a two-cycle engine for varying exhaust timing,
And an exhaust control device for a two-cycle engine including a control means for adjusting the opening of the exhaust valve at least according to the engine speed, whether the engine speed is equal to or higher than a set speed equal to or higher than an idle speed. An exhaust control device for a two-cycle engine, comprising: a determination unit that determines whether or not the engine speed is equal to or higher than the set speed, and a unit that forcibly rotates the exhaust valve.