JPH0531214Y2 - - Google Patents

Description

[Detailed explanation of the invention] [Purpose of the invention] (Industrial application field) This invention is designed to adjust the engine exhaust gas sent from the exhaust passage to the exhaust chamber, and to adjust the exhaust timing until the engine speed exceeds the specified rotation speed. The present invention relates to an exhaust control device for a two-stroke engine that controls when

(Prior art) Conventionally, in this type of two-stroke engine, in order to improve the output of the engine, for example,
As seen in Publication No. 26121, an exhaust chamber is installed in the middle of the exhaust passage, and the volume of the engine exhaust sent into the exhaust chamber is changed by the rotational position of a power valve installed at the exhaust chamber inlet, thereby increasing the exhaust pressure. Some devices are designed to match pulsation and prevent the generation of pulsation noise.

In addition, as another measure to improve engine output, for example, as shown in Utility Model Application No. 199677, a timing valve is placed in the exhaust passage so that it can appear and retract, and when the exhaust pressure exceeds a specified pressure, One idea is to advance the exhaust timing by retracting the timing valve from the exhaust passage.

All of these technologies seek to improve engine output over a wide range of engine speeds, from low engine speeds to high engine speeds.

(Problem that the invention aims to solve) By the way, conventional two-stroke engines cannot obtain the desired high engine output over a wide range of rotation speeds, from low rotation speeds to high rotation speeds. Therefore, among the above technologies,
It is thought that high engine output can be obtained by combining only the excellent points. In other words, it is possible to incorporate into one device the ability to vary the volume of engine exhaust gas sent into the exhaust chamber and the ability to advance the exhaust timing.

However, in both the former and the latter, these behaviors are directly correlated with the engine speed, but the engine speed range that is the operating command is slightly different between the former and the latter. For this reason,
If the former and the latter are incorporated into one device and attempted to be operated individually, the control system will become complicated, leading to erroneous operations, and the volume of the engine itself will increase, which is undesirable.

Therefore, while recognizing the difference in the engine speed that serves as the operating command for the former and the latter, we have developed a technology that allows the power valve and timing valve to interlock at a predetermined engine speed in one operating command system, thereby further increasing the engine output. It is hoped that it will appear.

This idea was made based on the above circumstances, and when the engine speed exceeds the specified speed, the power valve and timing valve are linked together to reduce the volume of engine exhaust gas sent into the exhaust chamber. An object of the present invention is to provide a two-stroke engine exhaust control device that advances the exhaust timing while reducing the amount of exhaust gas.

[Structure of the idea]

(Means for Solving the Problem) In order to achieve the above object, the two-stroke engine exhaust control device according to this invention provides a power source that can be rotated in conjunction with the engine speed in the exhaust passage of the two-stroke engine. The exhaust chamber communicates with the power valve via the valve, and the power valve is disposed close to the power valve so as to be able to engage with the radially outward protrusion of the power valve so as to be driven backward. A timing valve that is retracted from the exhaust passage in conjunction with the rotation of the power valve, a piston device that applies a pressing force so that the timing valve protrudes into the exhaust passage, and a pressing force of this piston device that can be adjusted. A set spring is provided, which adjusts the amount of engine displacement sent from the exhaust passage to the exhaust chamber as the power valve rotates, and engages with a protrusion of the power valve as the power valve rotates. The exhaust timing is controlled by a timing valve that is retracted from the exhaust passage.

(Function) This two-stroke engine exhaust control device has two
Cycle When the engine speed is below the specified speed, that is, when the engine speed is in the low speed range, the engine exhaust gas is sent from the exhaust passage to the exhaust chamber by the opening of the power valve. The timing valve protrudes into the exhaust passage due to the pressing force of the piston device, thereby delaying the exhaust timing.

As the engine speed increases, the power valve begins to rotate, and as it rotates, the volume of engine exhaust gas being sent into the exhaust chamber decreases. Next, when the engine speed reaches a specified speed, the power valve engages with the timing valve, and the rotational driving force of the power valve causes the timing valve to move and retreat from the exhaust passage to advance the exhaust timing. controlled.

In addition, the exhaust control device for two-stroke engines is
The power valve that communicates the exhaust chamber with the exhaust passage and the timing valve for exhaust timing are placed close to each other, and the radially outward protrusion of the power valve engages with the timing valve to directly drive it backwards, making it compact. While the structure is simplified, the timing valve and the power valve can be reliably driven in conjunction with each other, and there is no need for an interlocking means that takes up a large installation space to drive the timing valves in conjunction with each other. Furthermore, the pressing force of the piston device can be easily adjusted by adjusting the spring force of the set spring.

(Example) Hereinafter, an example of the exhaust gas control device for a two-stroke engine according to the present invention will be described with reference to the accompanying drawings.

In FIG. 1, reference numeral 10 indicates a two-stroke engine, and a piston 12 is slidably housed in a cylinder 11 of this engine 10. A scavenging port (not shown) that guides intake air into the cylinder chamber 13 in conjunction with the operation of the piston 12 and an exhaust port 14 that exhausts combustion gas burned in the cylinder chamber 13 are opened on the side wall of the cylinder 11. An exhaust passage 15 extends outward from the exhaust port 14.

A branch passage 16a is provided in the middle of the exhaust passage 15, and the exhaust chamber 16 is communicated with this branch passage 16a. Further, the branch path 16a is provided with an exhaust control device 17 that controls the engine exhaust gas sent from the exhaust passage 15 to the exhaust chamber 16, and advances the exhaust timing when the engine reaches a specified rotation speed. This exhaust control device 17 includes a timing valve 18 that controls exhaust timing and a power valve 19 that adjusts engine exhaust gas sent into the exhaust chamber 16.
It is equipped with A piston device 20 is connected to the timing valve 18, and the timing valve 18 is always projected into the exhaust passage 15 by the pressing force of a set spring 23 incorporated in the piston device 20. Set spring 2
The spring force 3 can be freely adjusted by adjusting the screwing amount of the cap 24.

On the other hand, a power valve 19 is rotatably provided in a branch path 16a connecting the exhaust passage 15 and the exhaust chamber 16, and a protrusion 25, such as a pin, is screwed or integrally connected to the power valve 19. are doing. The protrusion 25 of the power valve drives the timing valve 18. When the protrusion 25 engages the timing valve 18 as the power valve 19 rotates, this driving force causes the timing valve 18 to move out of the exhaust passage 15. It's starting to move backwards. Power valve 19 has a port 26
is drilled, and the position of the vent 26 changes as the power valve 19 rotates, thereby adjusting so that the engine exhaust gas being sent into the exhaust chamber 16 from the exhaust passage is gradually reduced.

Next, the operation based on the above configuration will be explained. Prior to that, a control system diagram of the motor that drives the power valve and a time chart showing the correlation between the rotation angle of the motor and the engine rotation speed are shown in FIGS. 4 and 5. Explain using. That is, FIG. 4 is a control block diagram of a motor 41, for example, a stepping motor, which rotationally drives the power valve 19. As seen in the figure, the engine rotation speed detection circuit 43
The actual engine rotational speed signal detected at is counted by the control unit 42 and given to the motor 41 as a pulse signal. Upon receiving the pulse signal, the motor 41 rotates the power valve 19 by a specified rotation angle based on the pulse signal, and sends an output signal to the power valve 1 so that the power valve 19 is held at that position.
I sent it out on 9th.

The operation of the motor 41 will now be explained in more detail with reference to FIG. 5 in relation to the rotational speed of the engine. When an ignition key (not shown) is turned on, the motor 41 is activated and rotated to the motor rotation angle position A. As the motor 41 rotates, the power valve 19 rotates, and the port 26 of the power valve 19 shown in FIG. 1 is closed, and the exhaust passage 15 and the exhaust chamber 16 are disconnected. During this time, carbon adhering to the sliding surface of the exhaust control device 17 is removed to ensure operability. At this time, as the power valve 19 rotates, the protrusion 2
Since the timing valve 18, which is engaged with the engine 5, is supported in a half-open state, the exhaust timing is accelerated and startability is improved. During idling, the same motor rotation angle A position is maintained as the setting at startup to prevent cylinder noise (engine noise).

Next, the engine speed is increased beyond the idling speed a, and clutch meet (starting) is performed.
Immediately before reaching the rotational speed b, the pulse signal from the control unit 42 that has been applied to the motor 41 is turned off, and the rotational angular position A of the motor 41 is returned to the initial rotational angular position B, and when starting The output will be improved. When the rotational angular position of the motor 41 is thus returned to its initial state, the port 26 of the power valve 19 is returned to the position shown in the figure, as seen in FIG. Then, a portion of the engine exhaust gas is sent from the exhaust passage 15 to the exhaust chamber 16 via the port 26.

Thus, from the exhaust passage 15 to the exhaust chamber 16
While some of the engine exhaust is being pumped into the
When the engine enters the (medium and high speed range), the engine speed detection circuit 43 detects the rotation speed c, and the control unit 42 converts the signal into a pulse signal and gives it to the motor 41.
moves to rotational angular position C, and the engine reaches rotational speed d.
(The engine speed range from c to d is approximately
It is held in the same position until it reaches 1500rpm). When the engine speed shifts from the rotational speed d to the rotational speed e, the motor 41, which has been held at the rotational angular position C, operates again, moves to the rotational angular position D, and is held at that position thereafter.

The power valve 19 and timing valve 18, which are driven by a motor that operates based on such a time schedule, operate as follows. That is, the engine rotates in the rotation speed region l shown in FIG.
(low and medium speed range), the power valve 19 is in the position shown in the first diagram as described above, the vent 26 is open, and a part of the engine exhaust gas is sent to the exhaust chamber 16. ing. In this case, the timing valve 18 is held in a protruding position to retard the exhaust timing.

Next, the engine speed increases and the engine speed c
When reaching this point, the power valve 19 rotates as the motor 41 operates, as shown in FIG.
As the rotational displacement occurs, the protrusion 25 provided on the power valve 19 engages with the timing valve 18.
This engagement timing is 1/1 when the port 26 is fully opened.
4 or the port 26 is completely blocked. Further, when the engine speed exceeds d, the protrusion 25 rotates while being engaged with the timing valve 18, resisting the spring force of the set spring 23 of the piston device 20 that was pressing the timing valve 18. The timing valve 18 is moved back from the exhaust passage 15 to accelerate the exhaust timing speed.

The timing valve 18 thus engaged with the protrusion 25 operates as the power valve 19 rotates, and eventually the timing valve 18 is completely retracted from the exhaust passage 15, as shown in FIG. As a result, even when the engine enters a high speed range, the engine exhaust only passes through the exhaust passage 15, so that high output can be obtained.

[Effect of idea]

As mentioned above, in this invention, when the engine speed is below the specified speed, a part of the engine exhaust gas sent into the exhaust chamber is adjusted, and when the engine speed reaches the specified speed or higher, the engine is powered up. Since the timing valve is operated so as to retreat from the exhaust passage in conjunction with the rotational force of the valve, the power valve and timing valve operate as one operating command system even if the engine speed ranges for operating commands are different, resulting in stable operation. can be controlled.

In addition, the exhaust control device for two-stroke engines is
The power valve that communicates the exhaust chamber with the exhaust passage and the timing valve for exhaust timing are placed close together, and the radially outward protrusion of the power valve directly engages with the timing valve to drive it backwards, making it compact. While the structure is simplified, the timing valve and power valve can be mechanically linked and driven reliably, eliminating the need for interlocking means that take up a large installation space to drive the timing valves in a linked manner. Become. Furthermore, the pressing force of the piston device can be easily adjusted by adjusting the spring force of the set spring.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an embodiment of the exhaust control device for a two-stroke engine according to this invention, FIG. 2 is a diagram showing the behavior of the power valve, and FIG. 3 is a diagram showing the behavior of the power valve and timing valve. Fourth
The figure is a schematic control block diagram of the motor that drives the power valve, and FIG. 5 is a diagram showing the correlation between the rotation angle of the motor and the engine rotation speed. 10... Two-cycle engine, 15... Exhaust passage, 16... Exhaust chamber, 16a... Branch path, 17... Control device, 18... Timing valve, 19... Power valve, 20... Piston device, 25 ...protrusion.

Claims (1)

[Scope of utility model registration request] An exhaust chamber that communicates with an exhaust passage of a two-stroke engine via a power valve that is rotatable in conjunction with the engine speed, and that engages with a radially outward protrusion of the power valve so as to be capable of being driven backwards. The timing valve is located close to the power valve, and is moved back from the exhaust passage in conjunction with the rotation of the power valve when the engine speed exceeds a specified number of rotations. A piston device that applies a pressing force to the piston device, and a set spring that is provided to be able to adjust the pressing force of the piston device,
A timing valve that adjusts the amount of engine displacement sent from the exhaust passage to the exhaust chamber as the power valve rotates, and that engages with a protrusion of the power valve and is moved back from the exhaust passage as the power valve rotates. An exhaust control device for a two-stroke engine, characterized by controlling exhaust timing.