JPH01159414A - Exhaust timing variable method for two-cycle engine and device therefor - Google Patents

Abstract

PURPOSE:To smooth a variation in a compression ratio at the whole speed range as well as to secure optimum output conformed to engine speed by installing two valve bodies in an exhaust passage free of rising and setting after superposing them on each other, and making these valve bodies retractable according to low or high in the engine speed. CONSTITUTION:A hole 2b is bored in an upper wall 2a of a housing 2 forming an exhaust passage 1, and a guide sleeve 11 is additionally installed on an upper circumferential surface of this hole 2b. In addition, a valve body 12 is installed in this guide sleeve 11 free of sliding motion, and a pin 12a of this valve body 12 is fitted in a long groove 11c of the guide sleeve 11. Furthermore another valve body 13 is installed in the valve body 12 free of sliding motion, and the pin 12a of the valve body 12 is fitted in a long groove 13a of the valve body 13. On the other hand, there is provided with an actuator 40 which interlocks a crankshaft 6, and its lever 41 is connected to the valve body 13. With the lowering of engine speed, by way of example, these valve bodies 12, 13 are projected from the upside in order, and each of upper parts A1, A2 of an exhaust port 1 is closed by each of the tips 12b, 13e.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method and apparatus for varying the exhaust timing of a two-stroke engine.

(Prior Art) As shown in FIGS. 9 and 10, a two-stroke engine has an upper wall 2a of a housing 2 forming an exhaust passage 1.
A valve body 3 is disposed so as to be freely retractable, and the valve body 3 is made to protrude in the low speed range of the engine. By blocking the upper part of the exhaust port 5, the compression ratio is increased as the exhaust timing approaches, thereby improving the output in the low speed range. Some devices are equipped with a variable exhaust timing device that moves the engine out of the exhaust port 5, advances the exhaust timing, lowers the compression ratio, and thereby improves the output in a high speed range.

By the way, in such a variable exhaust timing device, the valve body 3 is retracted from the exhaust port 5 between a low engine speed range and a high engine speed range, but the compression ratio changes rapidly before and after that. As a result, valleys are created in the output special.

[Purpose of the invention]

An object of the present invention is to provide a method and device for varying the exhaust timing of a two-stroke engine, which allows the compression ratio to be changed as smoothly as possible in order to obtain the optimum output in each rotation speed range. It is in.

[Structure of the invention]

In the method and device for varying the exhaust timing of a two-stroke engine of the present invention, a plurality of plate-shaped valve bodies are arranged so as to be movable on the upper wall of the exhaust passage, and the valve bodies are arranged at the engine rotational speed. As the engine speed increases, the upper part of the exhaust port is divided into multiple stages and blocked by protruding from above in order. I'm trying to evacuate more.

〔Example〕

1 to 4 show an apparatus for carrying out a method for varying the exhaust timing of a two-stroke engine according to the present invention.

In this device, a hole 2b having a circular cross section is bored in the upper wall 2a of the housing 2. A guide sleeve 11 is attached to the upper peripheral surface of this hole 2b.

The sleeve 11 has a flange 11a at one end (base end), and is fixed to the housing 2 by the flange 11a. This sleeve 11 has a distal end 11b forming the upper side of the exhaust port 5 and a part of the upper wall 2a of the exhaust passage 1, and has a long groove 110 on the lower surface of the intermediate portion.

In this device, two valve bodies 12,13 are used. The valve body 12 is slidably attached to the guide sleeve 11, and a pin 12a is attached to the intermediate portion. The upper end of this pin 12a is fitted into the long groove 11c of the guide sleeve 11. Further, this valve body 12 is urged toward the exhaust port 5 by a spring 14 disposed between its base end and the flange 11a. The valve body 13 has a substantially semi-cylindrical shape, and its upper plane portion is similar to the valve body 12.
It is slidably attached to the. The upper surface of this valve body 13 has a long W! 413a is formed in the long groove 138,
The lower end of the pin 12a is fitted. Further, this valve body 13 has a rod portion 13b at the axis of the base end.

A pin 13c is implanted at the end of the rod portion 13b, and a stopper 13d is fixed to the intermediate portion thereof.

As shown in FIG. 1, the valve body 12 is positioned in a protruding state with its pin 12a touching the end wall of the long groove 11G of the guide sleeve 11. The tip 12b faces the exhaust port 5 and closes the upper part of the exhaust port 5. Further, the valve body 13 is protruded by an actuator to be described later, and the stopper 13
d hits the flange 11a and is positioned, d3
In this state, the tip 130 of the valve body 13 is blocking the upper part A2 of the exhaust port 5.

The actuator 20 of this B1ff is configured with a shaft 21 installed parallel to the crankshaft 6, as shown in Fig. fj52. This actuator 20 has a governor that detects the rotational speed range of the crankshaft 6 and generates force in the six directions of arrows in FIG. 2 according to the rotational speed range.
2 and a cam mechanism 23 that receives the force of the governor mechanism and converts the force into a force in the rotational direction. The governor mechanism 22 includes a gear 24 fixed to the shaft 21 and a movable plate 26 that is movable in the axial direction with respect to the shaft 21 and is biased toward the gear 24 by a spring 25. There is. This movable plate 26 has a recess 27 facing the gear 24 side, and the bottom of this recess 27 has a
A first slant 26 having a small inclination angle with respect to a plane perpendicular to the axis 21
a, and a second slope 26b that is located on the outer periphery of the first slope 26a in the radial direction and has a greater slope than the ff11 slope 26a. A ball 28 is housed in a hollow portion formed between the recess 27 of the movable plate 26 and the side surface 24a of the gear 24. Furthermore, the movable plate 26 has a boss 26c on the opposite side from the teeth 1124. The cam mechanism 23 includes a rotating plate 29 that is rotatably arranged around the shaft 21 and can rotate in the axial direction;
It has a fixed plate 30 fixedly installed on the housing 2, facing the rotating plate 29. As shown in FIG. 1, the rotating plate 29 has a tongue piece 29a on its circumferential surface, and is also moved by a spring 31 in the +J direction.
Forced. Roughly speaking, this rotating plate 29 has an arc-shaped groove 29b on its side surface, and this groove 29b is formed to become deeper as it goes counterclockwise in FIG. The fixed plate 30 has four portions 30a on the surface facing the rotating brake 1-29, and a ball 32 is accommodated between this recess 30a and N29b of the rotating plate 29.

In the actuator 20 configured in this manner, the gear 24 of the governor mechanism is meshed with the gear 7 fixed to the crankshaft 6. When the crankshaft 6 is at rest, the balls 28G are positioned in contact with the shaft 21 as shown in FIG. It is in the first position located at the top.

Here, when the crankshaft 6 rotates, its rotational force is transmitted to the gear 24 of the governor mechanism 22 via the gear 7, and drives the shaft 21 at a rotation speed corresponding to the crankshaft 6. Then, a centrifugal force acts on the hole 28 of the governor mechanism 22, but the ball 28 cannot move in the radial direction due to resistance from the first slope 26a of the movable plate 26 until the number of revolutions exceeds a certain level. Therefore, when the rotational speed of the crankshaft 6 is in a low rotational speed range such as when starting or idling, the rotating plate 29 is not rotated and remains at the position Fi (first position) shown in FIG. .

When the rotation of the crankshaft 6 exceeds a certain number of rotations, the balls 28 move radially outward along the first slope 26a due to centrifugal force. Accordingly, the movable plate 26 is moved in the direction of the arrow, and the rotary plate 29 is moved through the boss 26c.
is pressed to the left in Fig. 2. When the rotating plate 29 is pressed, the ball 31 moves relative to the rotating plate 29.
As a result, the rotating plate 29 is rotated in the direction of arrow B in FIG. 1.

Then, the ball 28 is connected to the first slope 26a and the second slope 26b.
When the ball 28 reaches the boundary, it is resisted by the second slope 26b and remains there. Along with this, the rotation of the rotation plate 29 also stops at the position shown in FIG. 3 (second position). Note that the rotational speed of the crankshaft 6 during this period is defined as a medium speed rotational speed range.

When the rotation of the crankshaft 6 slows down, the balls 28 rest on the second slope 26b and move outward in the radial direction 31', further moving the movable plate 26 to the left in FIG. Therefore, the ball 31 is relatively
9 @29b, and as a result, the rotating plate 29 is further rotated in the direction of arrow C in FIG. When the ball 28 reaches the radially outermost end of the second slope 26b, the rotation of the rotation plate 29 stops at the position shown in FIG. 4 (third position).

Note that the rotational speed of the crankshaft 6 during this period is defined as a high rotational speed.

When the rotational speed of the sixth crankshaft decreases and reaches a low rotational speed range, the rotating plate 29 returns to the position shown in FIG. The position in Figure 2 vi! l1lI suru.

Further, this device includes interlocking means 40 for transmitting the power of the actuator 20 to the valve body 13.

This interlocking means 40 includes a lever 4 supported on the housing 2.
1. A notch 41a is provided at one end of this lever 41.
A pin 13c of the valve body 13 is formed in this notch 41a.
is engaged. Further, one end of a rod 42 is linked to the other end of this lever 41, and the other end of this rod 42 is linked to the tongue piece 29a of the rotating plate 29.

The operation of the variable exhaust timing device described above will be explained below.

When the engine is stopped, the rotating plate 29 is
It is in the first position shown in Figure a'51. At this time, valve body 1
3 is in a protruding state and blocks the upper part A2 of the exhaust port 5. Incidentally, at this moment, the valve body 12 is also in a protruding state due to the A' force of the spring 14, and the upper part A1 of the exhaust port 5 is
is blocked.

Even if the engine is started in this state, the rotating plate 29 is not rotated and remains at the first position during the low speed range. Therefore, during this period, the compression ratio is low and stable combustion can be achieved at low rotational speeds.

When the rotation of the crankshaft 6 becomes faster and reaches a medium rotation speed range, the actuator 20 is activated and the rotation plate 29 is rotated to the second position shown in FIG. 3. Then, as shown in FIG. 3, the valve body 13 is slightly recessed into the housing 2, and the upper part A2 of the exhaust port 5 is unblocked. Therefore, the compression ratio is slightly lowered and stable combustion can be achieved at medium speeds.

Furthermore, when the rotation of the crankshaft 6 becomes faster and reaches the n-speed rotation speed range, the rotation plate 29 is rotated to the third position shown in FIG. 4. Then, the valve body 13 is further recessed into the housing 2 from the position shown in FIG. At this time, the end wall of the length 13a of the valve body 13 and the pin 12a are engaged with each other, and the valve body 12 is pulled up together with the valve body 13 to the position shown in FIG. As a result, the upper part A1 of the exhaust port 5 is also opened, and the compression ratio further decreases. Therefore, stable combustion can be obtained in the 33I rotation speed range.

Note that when the rotation of the crankshaft 6 slows down, the exhaust timing variable device operates in the opposite manner to the above operation to adjust the valve body 12,
Prick 13.

5 to 8 show other apparatuses for implementing the exhaust timing variable method according to the present invention.

This device uses three valve bodies 51, 52, and 53, and the respective valve bodies 51, 52, and 53 are engaged with each other by a similar structure to the valve body 12, 13 of the above embodiment. ing.

That is, the valve body 51 is provided with a pin 51a, and the upper end of the pin 51a is fitted into the long groove 11c of the guide sleeve 11.

A pin 52a is also installed in the valve body 52, and the upper end of the pin 52a is connected to a long fi51 formed on the lower surface of the valve body 52.
It is inserted into b. A long groove 52 is provided on the upper surface of this valve body 52.
b is formed, and the long groove.

The lower end of the pin 51a of the valve body 51 is fitted into 52b. Further, the valve body 53 has a length 153a on its upper surface, and the lower end of the pin 52a of the valve body 52 is fitted into the section length m53a. The valve body 51, 5 formed in this way
2.53 are slidably superimposed on each other and have the above length W.
Ii11c, 51b determine the protruding position of the valve body 51, 52, and the long grooves 52t), 53a are necessary to sink the valve body 51, 52 into the housing. and,
Spring 54, 55 is interposed between the base end of each valve body 51, 52 and flange 11a of guide sleeve 11, respectively, and biases these valve bodies 51, 52 in the projecting direction. The valve body 53 has a one-tight portion 53b at the base end, and a pin 53G is provided at the end of the rod portion 53b, and a stopper 53d is provided at the intermediate portion. on the other hand,
The housing 2 includes an actuator 56 such as a pulse motor.
is installed, and a lever 5 is attached to the tip of the shaft 56a.
7 is fixed. There is a notch 5 at the tip of this lever 57.
7a is formed, and the notch 57a engages with a pin 53c of the valve body 53.

The actuator 56 used in this device is controlled based on, for example, a pulse signal output from a pickup coil of a rotation speed detecting means provided in an AC generator and comprising a signal rotor and a pickup coil. Ru.

The operation of the variable exhaust timing device described above will be explained below.

In the low speed range of the engine, each valve body 51.52
, 53 are in the state shown in FIG.

When the engine rotation reaches a predetermined number, the actuator 5
6 is driven at a constant angle to pull up the valve body 53 to the position shown in FIG. Therefore, the upper part A3' of the exhaust port 5 is opened. When the rotation of the engine further increases and reaches a predetermined rotation speed, the actuator 56 is driven at a certain angle, and the valve body 53
is pulled up together with the valve body 52, as shown in FIG. Therefore, the upper part A2' of the exhaust port 5 is opened.

Then, when the rotation of the engine reaches a high speed range, the actuator 56 is further driven at a certain angle, and the valve body 53
is further pulled up together with the valve bodies 51 and 52, as shown in FIG. Therefore, the upper part A1' of the exhaust port 5 is opened, and a compression ratio suitable for a high speed range can be obtained. Moreover, when the rotation of the engine becomes slow, each valve body 52, 53 .
54 returns to its original position in the reverse order of the above operating order.

In the above embodiment, only the lowest valve body is engaged with the seventh regulator, and the other valve bodies are respectively engaged with the lowest valve body through pins, but the method of the present invention can be applied, for example. It is also possible to carry out the first embodiment by directly linking each of the valve bodies to the actuator.

〔Effect of the invention〕

As described above, according to the method and device for varying the exhaust timing of a two-stroke engine according to the present invention, the compression ratio changes smoothly from low speed rotation to high speed rotation of the engine, and the optimum output corresponding to the n rotation speed is achieved. is turned blue.

[Brief explanation of the drawing]

1 to 4 conceptually show eight positions for carrying out the method for varying the exhaust timing of a two-stroke engine according to the present invention, and FIG. 1 is a sectional view showing the main parts of the device; Fig. 2 is a sectional view showing the actuator of the device, Figs. 3 and 4 are sectional views showing the operating state of the device, and Figs. 5 to 8 are the exhaust gas of the two-stroke engine according to the present invention. FIG. 9 is a cross-sectional view of a main part conceptually showing the operating state of another device for carrying out the variable timing method; FIG. 9 is a cross-sectional view of a main part showing a conventional variable exhaust timing device for a two-stroke engine; FIG. FIG. 2 is a front view showing the IJ1 blockage state of the exhaust port. DESCRIPTION OF SYMBOLS 1... Exhaust passage, 2... Housing, 2a... Upper wall, 5... Exhaust port, 6... Crankshaft, 11...
Guide sleeve, 11a... flange, 11c...
Long groove, 12...valve body, 12a...pin, 12b...
・Tip, 13... Valve body, 13a... Long vortex, 13b.
...Rod part, 13c...Bin, 13d...Stopper, 13e...Tip, 14...Spring, 20...
...Actuator, 51...Valve body, 51a...Bin, 51b...Long groove, 52...Valve body, 52a...
Pin, 52b...long groove, 53...valve body, 53a...
・Long groove, 53b...Rod part, 53c...Bin, 5
3d...Stopper, 54.55...Spring, 56...Actuator, 57...Lever, 57a
...Notch, A, A1# A2, A1'*Δ2',Δ3'...
Above the exhaust port. Applicant: Suzuki Shirobosha Industry Co., Ltd.? Figure 2 Figure 3 Figure 4

Claims (3)

[Claims] (1) A plurality of plate-shaped valve bodies are stacked one on top of the other and are disposed on the upper wall of the exhaust passage so that they can appear and retract from each other, and as the engine speed decreases, the valve bodies are made to protrude from above in order to open the upper part of the exhaust port. A method for varying the exhaust timing of a two-stroke engine, characterized in that the valve is closed in multiple stages, and each valve body in a closed state is evacuated from the exhaust port in sequence from the bottom as the rotational speed of the engine increases. (2) A plurality of plate-shaped valve bodies are stacked one on top of the other and disposed on the upper wall of the exhaust passage so that they can appear and retract freely, and an actuator that is driven in relation to the engine speed is engaged with the valve bodies. As the engine speed decreases, the valve bodies are sequentially protruded from above to block the upper part of the exhaust port in multiple stages, and each valve body that is in a closed state is protruded from below as the engine speed increases. A variable exhaust timing device for a two-stroke engine, characterized in that the exhaust timing is evacuated from an exhaust port in order. (3) The lowest valve body is connected to the actuator, and each valve body except the lowest valve body is biased toward the exhaust port by a spring, and the valve bodies that are in contact with each other are connected by pins and long grooves. When the lower valve element is recessed into the upper wall of the exhaust passage by a predetermined distance, the upper valve element is locked and moved together with the lower valve element. Characteristic Claim No. (
2) The variable exhaust timing device for a two-stroke engine as described in item 2).