JPS6255415A - Exhaust timing control device for two-cycle engine - Google Patents

Abstract

PURPOSE:To ease the exhaust timing adjustment in a two-cycle engine, in which the exhaust timing control is made through opening or closing the upper brim of an exhaust port by using a closing valve, by installing an actuator, which drives the said closing valve, to the crank case together with connecting this actuator to the closing valve via an easily detachable link mechanism. CONSTITUTION:In driving a valve 10, which opens or closes the upper brim of an exhaust port of an two-cycle engine in accordance with the engine operating condition, by means of an air cylinder 11, the air cylinder 11 is installed to the crank case 1, while a rod 19a of the air cylinder 11 is connected to the valve 10 via an arm 22 and link 23 and 24. This link mechanism 20A is constituted in such a manner that it can be detached as occasion demands.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to an engine exhaust timing control device, and in particular to an engine exhaust timing control device.
The present invention relates to an exhaust timing control device used in cycle engines.

``Conventional Technology J Generally speaking, the engines installed in vehicles, etc. are of the low-speed type, which focuses on power characteristics when driving at low speeds (low speed range), and those that emphasize power characteristics when driving at high speeds (high speed range). They are roughly divided into two types: high-revving types that place emphasis on engine output. It is now possible to obtain

However, in the former case, the output reaches a peak in the high rotation range, and in the latter case, the output is low.

Since it has the characteristic that the output in the rotation range is lower than the former, by increasing the output in the low rotation range while maintaining high output in the high rotation range, it is possible to increase the output from low speed driving. Improving the output characteristics over the entire range up to high-speed driving is being considered, and one specific solution is to change the engine exhaust JCTL between low and high speeds. There is.

As an example of a conventional structure in which the above solution is applied to a two-stroke engine, a valve is provided near the top of the opening of the exhaust passage to the inner surface of the cylinder, and this valve is opened and closed according to the engine speed. It is known that the edge of the opening on the top dead center side is moved in the sliding direction of the piston, thereby changing the timing of communication between the exhaust passage and the inside of the cylinder during the downward movement of the piston. ing. In the above-mentioned exhaust timing control device, the valve installed at the top of the exhaust passage is usually driven via a wire by a pulse motor fixed to the frame side, where there is less vibration, with a vibration isolating material interposed. ing.

"Problems to be Solved by the Invention" The present invention aims to solve the following drawbacks in the conventional techniques described above.

In other words, in the above-mentioned technology, the driving force of the pulse motor is transmitted to the valve via a wire, and since the pulse motor itself is susceptible to vibration, the bell smoke is placed on the side of the frame where there is relatively less vibration, such as a rubber material. The pulse motor is fixed with a vibration isolating material interposed, so that the pulse motor may move slightly.
In addition, the wire connecting the pulse motor and the valve may lengthen due to changes over time, so there is a risk that the valve operation may lack stability, and maintenance must be performed frequently to prevent this. be.

In addition, as another example of an exhaust timing control device, there is a structure in which the valve drive source is an actuator such as a vibration-resistant air cylinder, and this actuator is attached to the cylinder to directly operate the valve. In this case, when the cylinder is removed from the crankcase during maintenance, the air system or hydraulic system piping must also be removed at the same time, and then the piping must be reassembled and checked for leaks, which makes maintenance work unnecessary. The problem is that it is troublesome.

This problem is particularly important in the case of engines mounted on racing vehicles.

``Object of the Invention'' The present invention has been made in view of the above circumstances, and is an exhaust timing control device for a two-stroke engine that is capable of reliably operating the valve as desired and has excellent maintenance workability that requires the removal of the cylinder. The purpose is to provide

"Means for Solving the Problem" In order to achieve the above object, the present invention has a configuration in which an actuator for driving a valve is attached to the crankcase, and the actuator is connected to an exhaust timing control valve via a removable link mechanism. And so.

"Embodiment" Hereinafter, a preferred embodiment of the present invention will be described in detail based on FIGS. 1 to 3.

FIG. 1 is a partial side view of a two-stroke engine, FIG. 2 is a longitudinal cross-sectional view thereof, and FIG. 3 is a cross-sectional view taken along the line ■-■ in FIG. 2.

The engine of this embodiment is a V-type four-cylinder engine with an included angle of 90 degrees, and each cylinder 2 attached to a common sliding crankcase l is arranged so that every other cylinder is located on the same plane. Moreover, these adjacent cylinders are arranged so as to form an included angle of 90 degrees when viewed from the side. Note that 3 in the figure is a cylinder head.

2, 4 is a piston slidably inserted into the cylinder 2, 5 is a plurality of scavenging passages provided at intervals in the circumferential direction of the cylinder 2, 6 is an exhaust passage, and 7 is an exhaust gas passage. This is a rib provided near the opening of the passage 6 to the inner surface of the cylinder, extending in the vertical direction in the figure, and this rib 7 reinforces the vicinity of the opening 6a of the exhaust passage 6 to the inner surface of the cylinder, and also prevents the piston ring from radially outward. This serves to prevent the opening 6a from spreading outward and hitting the upper or lower edge of the opening 6a. An exhaust timing control device 8 according to the present invention is provided near the top of the exhaust passage 6 and between both exhaust passages 6.

The exhaust timing control device 8 includes an exhaust passage 6 as shown in FIG.
A partition wall 9 is provided at the upper part of the exhaust passage 60 and divides the vicinity of the open end 6a of the exhaust passage 60 in the sliding direction of the piston 4, that is, in the vertical direction in the figure, and a partition wall 9 that penetrates the upper wall of the exhaust passage 6 and divides the vicinity of the opening 6a of the exhaust passage 6 into a longitudinally intermediate portion. is located in the exhaust passage 6 and opens and closes between the partition wall 9 and the upper wall of the exhaust passage 6, and as shown in FIGS. 1 and 3, a control valve IO is operated. It is generally constituted by a driving means 11 for driving.

Next, to explain these details, the partition wall 9
is provided integrally with the cylinder 2 at a position spaced downward by a predetermined distance G from the upper edge 6b of the opening 6a, and forms a main passage 12 between the exhaust passage 6 and the lower wall surface of the exhaust passage 6. A sub-passage I3 is formed between the passage 5 and the upper wall thereof. The interval G is set based on the difference between the exhaust timing at high revolutions and the exhaust timing at low revolutions, which is set at the stage of setting the output characteristics of the engine. Further, as shown in FIG. 3, the end surface of the partition wall 9 on the inside side of the cylinder 2 is set back a predetermined distance from the inner circumferential surface 2a of the cylinder 2 toward the downstream side of the exhaust passage 6, and , is formed in a curved shape along the inner circumferential surface 2a.

The control valve IO has both ends formed in a cylindrical shape and a middle portion formed in a semicircular cross section, and is formed on the upper wall of the exhaust passage 6 so as to cross the exhaust passage 6. It is rotatably attached to the through hole 14. The longitudinal intermediate portion of the control valve IO is exposed in the exhaust passage 6 and closes the sub passage 13 when the valve 10 is rotated to a predetermined angular position, while the valve IO closes the sub passage 13. When it is rotated by a predetermined angle from this state, the sub passage 13 is brought into communication.

Further, as shown in FIG. 3, the control valves IO are arranged coaxially with each other in every other cylinder 2, and the control valves 1O arranged coaxially with each other are arranged coaxially with each other.
11O are connected such that their mutually opposing ends rotate integrally by a removable connection means 15.

The connecting means 15 includes a connecting female member 16 attached to an opposite end of one control valve lO so as to be movable in the length direction of the valve and rotate integrally with respect to the valve, and a connecting female member 16 attached to the opposite end of the control valve 10 on the other side. is attached to the end of the valve so as to be movable in the longitudinal direction of the valve and to rotate integrally with the valve, and its head 17a is fitted into the recess 16a of the female connecting member 16, so that the female connecting member 1 a connecting male member 17 that can rotate integrally with the connecting male member 17; and a flange 18 that is slidably provided on the outer periphery of the connecting male member 17 and screwed to a flange portion 16b formed integrally with the connecting female member 16.
It is composed of. The above-mentioned connecting means 15 can be easily removed by simply removing the screws connecting the flange 18 and the flange portion 16b.

On the other hand, as shown in FIG. 1, the exhaust timing control valve driving means 11 includes an air cylinder (actuator) 19 attached to the crankcase l by a fixing means such as a retaining ring, and the driving force of the air cylinder I9. , two link mechanisms 2OA and 20B each transmitting information to the control valves 1O11O, which are arranged vertically apart in the figure.

Both link mechanisms 2OA and 20B have the same configuration, and are given the same reference numerals here to simplify the explanation. To explain this link mechanism, a rod 21 is rotatably disposed in a support portion (not shown) extending from the crankcase l in parallel with the control valve H, and the tip of the rod 21 is connected to the An arm 22 that comes into contact with the output shaft 19a of the cylinder 19 and is rotated is integrally attached. Further, an arm 23.23 is integrally attached to the rod 21 with a predetermined opening angle.

One end of a rod 24 is pin-coupled to the swinging tip of the arm 23, and the other end of the rod 24 is rotatably and removably screwed to the tip of the arm portion 10a extending from the control valve IO. (see figure).

The air cylinder 19 is connected to a compressed air supply source through an air pipe, and a solenoid valve (both not shown) installed in the air pipe is operated according to the rotational speed of the engine. Accordingly, the control valve IO can be rotated to either fully open or fully closed position via link mechanisms 20A and 20B. The arm 22 is biased by a spring (not shown) to rotate counterclockwise in FIG.
When 9a is retracted, the rod 21 is simultaneously rotated counterclockwise in FIG.

According to the exhaust timing control device configured as described above, by rotating the control valve 10 in a predetermined direction according to the rotation speed of the engine, the output characteristics of the engine can be increased over the entire rotation range.

That is, when the engine is operating in a low rotation range, the air cylinder 19 driven based on this information is operated to advance the output shaft 19a, and accordingly, the air cylinder 19 is controlled via the link mechanisms 2OA and 20B. Valve 10 is the second
The rotation operation is performed so as to close the sub passage 13 as shown by the two-dot chain line in the figure.

In this way, when the sub-passage I3 is closed, the outflow of exhaust gas from the sub-passage 13 is blocked, and the exhaust gas from the engine is transferred from the upper edge of the piston 4 in the downward stroke to the lower end of the partition wall 9. It will start from the moment it reaches . As a result, the exhaust timing of the engine is delayed by an amount corresponding to the distance G between the upper edge 6b of the opening 6a and the partition wall 9, and appropriate exhaust is obtained at low rotation speeds, resulting in engine output in the low rotation range. Improvements will be made.

When the engine reaches a high speed range from this state, the output shaft 19a of the air cylinder 19 is operated to retract and the control valve 1o is rotated in the opposite direction to the above-mentioned direction. As shown in FIG.
is communicated. In this state, exhaust gas is discharged from the sub passage 13, and the position of the piston 4 at which exhaust starts is raised from the partition wall 9 to the upper edge 6b of the opening 6a, that is, the exhaust timing is advanced. As a result, appropriate exhaust is performed at high speeds, and at the same time, engine output in the high speed range is improved.

Therefore, an improvement in engine output characteristics can be obtained over the entire rotation range.

In addition, in the exhaust timing control device having the above configuration, the air cylinder (actuator) 19, which is resistant to vibration, is used as the valve drive source, and this air cylinder I9 is directly operated without intervening a vibration isolating material such as a rubber material. Since the air cylinder 19 and the control valve 10 are connected to the crankcase by a link mechanism that does not change much in temperature or over time, the control valve can be operated reliably as desired. can be done.

Also, fix the air cylinder 19 to the crankcase l,
Moreover, since the link mechanism connecting the air cylinder 19 and the control valve 10 is removable, when the cylinder is removed, the connection between the link mechanisms 2OA, 20B and the control valve IO is cut off, and the connection between the adjacent control valves 20A and 20B is cut off. This can be carried out by simply separating the connecting means 15 that connects the cylinders 2 to each other, and therefore maintenance work that requires removing the cylinder 2 can be performed easily and in a short time.

Furthermore, in the above exhaust timing control device, each control valve 10
Since each of the control valves 10 is driven by a common air cylinder 19, the structure can be simplified and the weight reduced, and the control valves 10 can be operated at the same time without any time delay. can get.

In the above embodiment, an air cylinder is used as the control valve drive source, but a hydraulic cylinder may be used instead. Furthermore, it goes without saying that the present invention is not limited to multi-cylinder engines, but can also be applied to single-cylinder engines.

"Effects of the Invention" As explained above, the exhaust timing control device for a two-cycle engine according to the present invention provides the following excellent effects.

(a) A vibration-resistant actuator is used as the valve drive source, and the actuator can be fixedly attached to the crankcase without using a vibration isolating material, and the actuator and control valve can be connected at Since the control valves are connected by a link mechanism that does not change or change over time, the control valve can be operated reliably as desired.

(b) Furthermore, since the actuator is fixed to the crankcase and the link mechanism that connects the actuator and control valve is removable, when removing the cylinder for maintenance, you can simply remove the link mechanism without removing the piping system. It can be carried out with
Maintenance work that requires removing the cylinder 2 can be performed easily and in a short time, and is particularly suitable for application to racing engines.

[Brief explanation of the drawing]

1 to 3 show one embodiment of the present invention, in which FIG. 1 is a partial side view of a two-stroke engine, FIG. 2 is a vertical sectional view thereof, and FIG. It is a cross section and a side view along the line. !・・・・・・ Crankcase, 2・・・・・・
Cylinder, 4... Piston, 6.
...exhaust passage, 6a...opening,
6b... Upper edge, 8... Exhaust timing control device, 9... Bulkhead, 10...
Control valve, 11... Drive means, 12
...Main passage, 13...Sub passage, 15...Connection means,

Claims (1)

[Claims] The upper part of the opening of the exhaust passage communicating with the inside of the cylinder of a two-cycle engine is opened and closed using pulp, and the timing of communication between the inside of the cylinder and the exhaust passage by a piston slidably fitted inside the cylinder is changed. An exhaust timing control device for a two-stroke engine, characterized in that an actuator for driving the valve is attached to the crankcase, and the actuator is connected to the valve via a removable link mechanism.