JPH02163410A - Exhaust controller for two-cycle engine - Google Patents

Abstract

PURPOSE:To improve the suction efficiency and scavenging efficiency by arranging a conical guide cylinder whose upstream edge is connected, in shiftable ways in an exhaust flow passage direction, in an expansion chamber formed at the downstream edge of an exhaust pipe, and by shifting the downstream edge according to the engine operation state. CONSTITUTION:A conical guide cylinder 14 in which a movable cylinder part 17 slidingly contacts along a fixed cylinder part 16 is arranged in shiftable ways in the exhaust flowing direction 15 at the upstream edge part in an expansion chamber 6 formed on the downstream edge of an exhaust pipe 5, and the exhaust gas supplied from an engine 1 is introduced into the expansion chamber 6 through the guide cylinder 14, and negative pressure waves are generated in the conical guide cylinder 14. A control means 25 drives a servomotor 23 according to the operation state of the engine 1, and shifts the downstream edge of the guide cylinder 14 through a driving member 19, and the stable output characteristic is obtained by varying the generation position of the negative pressure waves. Thus, the driving part of the guide cylinder can be made small-sized and lightweight, improving the suction efficiency and scavenging efficiency of the engine body.

Description

Detailed Description of the Invention A1 Object of the Invention (1) Industrial Application Field The present invention is directed to an engine in which an upstream end of an exhaust pipe is connected to an exhaust port of an engine body, and an expansion chamber is connected to a downstream end of the exhaust pipe. The present invention relates to an exhaust control device for a two-stroke engine.

(2) Prior Art Conventionally, such a device is known from, for example, Japanese Utility Model Application Publication No. 1623/1983.

(3) Problems to be Solved by the Invention In the above conventional system, the muffler body forming the expansion chamber is movable in the axial direction and connected to the exhaust pipe, and the muffler body is driven in accordance with the operating state of the engine. This improves the air supply efficiency and scavenging efficiency of the engine body.

However, since the muffler main body is relatively large and heavy, a large driving force is required.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide an exhaust control device for a two-stroke engine that solves the above-mentioned conventional problems by making the driven portion smaller and lighter.

B1 Structure of the Invention (1) Means for Solving the Problems The present invention provides that the downstream end of the exhaust pipe is basically formed into a conical shape whose diameter increases toward the downstream side, and the upstream end in the expansion chamber The upper 2ii ends of the guide tube disposed in the section are connected, and the guide tube is configured such that its downstream end is movable along the exhaust flow direction, and the downstream end is moved according to the engine operating state. The first feature is that the drive member is connected to the drive member.

Further, in the present invention, the downstream end of the exhaust pipe is connected to the upstream end of a guide cylinder which is basically formed into a conical shape with its diameter increasing toward the downstream side and is disposed at the upstream end in the expansion chamber. The guide tube is configured to be able to vary the substantial spread angle of the exhaust gas from the exhaust pipe to the expansion chamber, and is coupled to a drive member to change the spread angle in accordance with engine operating conditions. This is the second feature.

(2) Effect According to the first feature, since the exhaust gas is guided to the expansion chamber through the conical guide tube, a negative pressure wave can be generated in the guide tube, and the downstream end of the guide tube can be generated. By moving the negative pressure wave, the generation position of the negative pressure wave can be changed depending on the engine operating state, and stable output characteristics can be obtained from the engine high load state to the low engine load state.

Further, according to the second feature, since the exhaust gas is guided to the expansion chamber through the conical guide tube, a negative pressure wave can be generated in the guide tube, and the exhaust gas from the guide tube to the expansion chamber can be generated. By changing the spread angle, the magnitude of the negative pressure wave and the position of the negative pressure generating part can be changed according to the engine operating conditions, making it possible to obtain stable output characteristics from engine high load conditions to low engine load conditions. Become.

(3) Examples Examples of the present invention will be explained below with reference to the drawings.
First, in FIG. 1 showing a first embodiment of the present invention, there is a cylinder on the inner surface of a cylinder bronck l that constitutes the engine body of a two-cycle engine E mounted on a motorcycle, and is slidable inside the cylinder bronk l. An exhaust port 3 is opened and opened and closed by a piston 2 fitted in the exhaust port 3, and an exhaust timing control valve 4 is disposed above the exhaust port 3 to control the opening and closing timing of the exhaust port 3. The upstream end of an exhaust pipe 5 is connected to the exhaust port 3, and the exhaust pipe 5 is connected to a muffler (not shown) via a pipe member 7 that defines an expansion chamber 6 therein.

The exhaust % J] flin+ control valve 4 provided at the exhaust port 3 is fixed to a drive shaft 10 rotatably disposed on the cylinder lock 1, and this drive shaft 10 is composed of a pulley, a transmission wire, etc. It is connected to a servo motor 12 via a transmission mechanism 11 . Further, the servo motor 12 is provided with a potentiometer 13 for detecting the operating amount of the servo motor 12, that is, the opening degree of the exhaust time control valve 4.

Referring also to FIG. 2, the pipe member 7 is formed so that its cross-sectional area is larger than that of the exhaust pipe 5, and the upstream end thereof has a diameter that decreases toward the upstream side. A tapered tube portion 7a is provided. The upstream end of the expansion chamber 6 formed by the pipe member 7 is basically formed into a conical shape whose diameter increases toward the downstream side of the expansion chamber 6, and the downstream end is connected in the exhaust flow direction. A guide tube 14 configured to be movable along the guide tube 15 is disposed, and the upstream end of the guide tube 14 is connected to the downstream end of the exhaust pipe 5.

The guide tube 14 includes a fixed tube portion 16 connected to the exhaust pipe 5,
It consists of a movable cylinder part 17 that is movable along the exhaust flow direction 15. The fixed cylinder part 16 is formed in a conical shape whose diameter becomes smaller toward the upstream side, and is fixed to the upstream end of the tube member 7 with the upstream end protruding. is connected to the downstream end of the exhaust pipe 5. Moreover, the movable cylinder part 17 is arranged so as to be movable along the exhaust flow direction 15 within the expansion chamber 6, and an upstream straight pipe part 17a and a downstream Taber pipe part 17b are integrally connected. It consists of being done. The inner diameter of the straight tube portion 17a is set to be slightly larger than the outer diameter of the large diameter end, that is, the downstream end, of the fixed tube portion 16, and the straight tube portion 17a is in contact with the outer surface of the large diameter end of the fixed tube portion 16. The fixed cylinder portion 16 is disposed so as to surround the portion of the fixed cylinder portion 16 facing into the expansion chamber 6 so as to move in the exhaust flow direction 15 .

Further, the Taber pipe portion 17b is formed in a conical shape whose diameter increases toward the downstream side along the exhaust flow direction 15, and its small diameter end, that is, the upstream end thereof, is coaxially connected to the straight pipe portion 17a.

A drive shaft 18 having an axis perpendicular to the exhaust flow force 1i115 is rotatably supported on the pipe member 7, and a drive member 19 fixed to the drive shaft 18 is attached to the movable cylinder portion 17 of the guide cylinder 14. Concatenated. That is, the drive member 19 is formed to straddle the Taber tube portion 17b of the movable cylinder portion 17, and the Taber tube portion 17b is connected to the drive member 19 via a pair of connecting pins 20 parallel to the drive shaft 18. be done.

Then, the movable cylinder portion 17 moves in the exhaust flow direction 15 in response to the swinging motion of the drive member 19 due to the rotation of the drive shaft 18,
As a result, the downstream end of the movable cylinder portion 17, that is, the downstream end of the guide cylinder 14, moves along the exhaust flow direction 15.

A pulley 2 is attached to the protruding end of the drive shaft 18 protruding from the pipe member 7.
1 is fixedly attached thereto, and this pulley 21 is connected to a servo motor 23 via a transmission mechanism 22 such as a transmission wire.

Moreover, a potentiometer 24 is attached to the servo motor 23 to detect the operating amount of the servo motor 23, that is, the position of the downstream end of the guide cylinder 14 within the expansion chamber 6.

The operation of both servo motors 12,23 is controlled by control means 25. Further, the control means 25 includes the engine rotation speed NE detected by the engine rotation speed detector 26 and the throttle opening degree θA detected by the throttle opening degree detector 27. , the exhaust temperature T7 detected by the exhaust temperature detector 28 that detects the exhaust temperature in the expansion chamber 6, the engine cooling water a"rc detected by the cooling water temperature detector 29, and the atmosphere detected by the atmospheric temperature detector 30. The temperature TA and the atmospheric pressure PA detected by the atmospheric pressure detection 131 are inputted, as well as the detected value of the operating amount of the servo motor 12.23 by the potentiometer 13.24.Furthermore, the amount of bleed air in the carburetor (not shown) is controlled. The operation of the solenoid valve 32 and the operation of the oil pump 33 for this purpose are controlled by the control means 25.

In this control means 25, the opening degree of the exhaust timing control valve 4, that is, the operating amount of the servo motor 12 is controlled according to the engine operating state, and the downstream end position of the guide tube 14 is moved according to the engine load. The operation of the servo motor 23 is controlled according to the control procedure shown in FIG.

In FIG. 3, data is read in a first step St, and an atmospheric pressure correction coefficient KPM necessary for the correction calculation in a fourth step S4 is retrieved in a second step S2. That is, as shown in FIG. 4, a map is prepared in advance in which the atmospheric pressure correction coefficient KPA is determined according to the atmospheric pressure PA, and when this map is used, 0 is searched for in the atmospheric pressure correction coefficient. In the next third step S3, an atmospheric temperature correction coefficient KTA necessary for the correction calculation in the fourth step S4 is retrieved. That is, as shown in FIG. 5, a map in which the atmospheric temperature correction coefficient K7A is determined in accordance with the atmospheric temperature TA is prepared in advance, and a search is made for the atmospheric temperature correction coefficient according to this map.

In the fourth step S4, the above-mentioned second and third steps S2. Throttle opening degree θTII read by equation (1) using correction coefficient KPA+KTk obtained in S3
is corrected.

θTH'”'θTHX KPAX Krs・・・・・・
(1) In the next fifth step S5, the operating amount of the servo motor 23 is searched based on the engine speed N and the corrected throttle opening θTH'.

That is, as shown in FIG. 6, the amount of rotation θ of the drive member 19 is the amount of operation of the servo motor 23. is predetermined as a three-dimensional map based on the throttle opening θ□′ and the engine rotational speed N, and the rotation amount θ8 is obtained according to this map. Here θ. As the value increases, the downstream end of the guide tube 14 moves toward the exhaust flow direction 15.
This indicates movement upstream along the .

In the sixth step S6, the exhaust gas temperature correction coefficient KT necessary for the correction calculation to be performed in the next seventh steno knob S7 is searched.

That is, as shown in FIG. 7, the map in which the exhaust temperature correction coefficient KTE is determined according to the exhaust temperature T is 4! According to this map, the exhaust temperature correction coefficient is searched for. Furthermore, in the seventh step S7, the operating amount θD is corrected according to the following (2) 2 using '[ as the correction coefficient.

θIl′ −θ. ×7. (2) In the final eighth step S8, the operating amount θ obtained from the above equation (2). ' is output, and its operating amount θ.

The servo motor 23 will be operated accordingly.

Next, to explain the operation of this example of a real box, by controlling the opening degree of the exhaust timing control valve 4 according to the engine operating condition, the output of the two-cycle engine E can be adjusted as shown by the diagonal line downward to the left in FIG. increases to In addition, by controlling the downstream end position of the guide tube 14 according to the engine load, two
The output of the cycle engine E increases as shown by the diagonal line downward to the right in FIG. That is, in the low-load operating range of the two-stroke engine E, the downstream end of the guide tube 14 is located on the downstream side along the exhaust flow direction 15, so that exhaust gas flows into the guide tube 14.
The location where the negative pressure generated as the pressure is introduced into the expansion chamber 6 is located relatively downstream at the upstream end of the expansion chamber 6, and the time interval between the exhaust and scavenge strokes is relatively long. Correspondingly, the negative pressure generating section can be located relatively far from the exhaust port 3, and in the high-load operating range of the two-cycle engine E, the downstream end of the guide tube 14 can be located on the upstream side along the exhaust flow direction 15. Since the exhaust gas is located in the guide tube 14
The site where the negative pressure generated as a result of being introduced into the expansion chamber 6 is located relatively upstream at the upstream end of the expansion chamber 6, and the time interval between the exhaust and scavenge strokes is relatively short. Correspondingly, the negative pressure generating section can be positioned relatively close to the exhaust port 3, and by controlling the position of the negative pressure generating section in this way, fresh air introduction and combustion gas exhaust can be adjusted according to the engine operating condition. By doing so, the output of the two-stroke engine E can be improved.

Moreover, the part that is driven to improve the output is the expansion chamber 6.
There is only a movable cylindrical portion 17 that constitutes the guide tube 14, and the driving force for driving the movable cylindrical portion 17 is relatively small.

FIG. 9 and FIG. 1O show a second embodiment of the present invention, and parts corresponding to the first embodiment are given the same reference numerals.

Exhaust flow direction 1 in the expansion chamber 6 formed by the pipe member 7
At the upstream end along 5, there is an exhaust pipe 5 connected to the exhaust port 3.
A guide cylinder 34 is provided, which includes a fixed cylinder part 36 connected to the exhaust gas flow direction 15 and a movable cylinder part 37 that is expandable and retractable along the exhaust flow direction 15.

The fixed cylindrical portion 36 is formed into a conical shape whose diameter becomes smaller toward the upstream side, and the upstream end of the fixed cylindrical portion 36 is coaxially connected to the exhaust pipe 5 that is inserted into the pipe member 7. Moreover, the movable cylinder part 37 is made up of first, second, and third conical cylinder members 3B, 39.40 whose diameters become smaller toward the upstream side and are connected coaxially and relatively movably along the exhaust flow direction 15. That is, the inner diameter of the upstream end of the first conical cylinder member 38 is formed to be slightly larger than the outer diameter of the downstream end of the fixed cylinder part 36, and the inner diameter of the upstream end of the second conical cylinder member 39 is formed to be slightly larger than the outer diameter of the downstream end of the first conical cylinder member 38. It is formed slightly larger than the diameter, and the third
The inner diameter of the upstream end of the conical cylindrical member 40 is slightly larger than the outer diameter of the downstream end of the second conical cylindrical member 39 . Further, at the downstream end of the fixed cylinder part 36, there is a locking collar 3 that extends outward in the radial direction.
At the upstream end of the first conical cylindrical member 38, an engaging flange 38a that can be engaged with the locking flange 36a from the upstream side along the exhaust flow direction 15 is provided and extends radially inward, The downstream end of the first conical cylinder member 3B is provided with a locking collar 38b that extends outward in the radial direction, and the upstream end of the second conical cylinder member 39 is provided with a locking collar 38b that extends along the exhaust flow direction 15. An engaging collar 39a that can be engaged from the upstream side is provided to protrude radially inward, a locking collar 39b that protrudes radially outward is provided at the downstream end of the second conical cylinder member 39, and a third At the upstream end of the conical cylinder member 40, an engaging collar 40a that can be engaged with the locking collar 39b from the upstream side along the sushi air flow direction 15 is provided so as to protrude radially inward. Further, both ends of a locking rod 41 extending in the -diameter direction are fixed near the downstream end of the third conical cylinder member 40.

A drive member 19 fixed to a drive shaft 18 rotatably supported by the tube member 7 is connected to the third conical cylinder member 40 via a connecting pin 20.20.

The servo motor 23 connected to the drive shaft 18 is operated by the control means 2 according to the control procedure shown in FIG. 3 in the first embodiment.
5, the two-stroke engine E
The operation of the servo motor 23 is controlled so that the drive member 19 swings to the left in FIG. 9 as the rotation speed increases.

To explain the operation of this second embodiment, as the two-stroke engine E rotates at a high speed, the drive member 19 swings to the left in FIG. As a result, the third conical cylinder member 40 first moves upstream along the exhaust flow direction 15, and after the locking rod 41 comes into contact with the locking collar 39b of the second conical cylinder member 39, the second conical cylinder member 39 moves upstream along the exhaust flow direction 15, and when the locking rod 41 further comes into contact with the locking flange 38b of the first conical cylinder member 38, the first conical cylinder member 38 also moves upstream along the exhaust flow direction 15. Moving. In this way, the movable cylinder portion 37 in the guide cylinder 34 is extended.

Due to the contraction operation, the position of the downstream end of the guide tube 34 moves, and the magnitude of the negative pressure wave generated when exhaust gas enters the guide tube 34 and the negative pressure generation site change. That is, when the engine is running at low load, a relatively small negative pressure wave is generated at a position relatively far from the exhaust port 3, and when the engine is running at high load, a relatively large negative pressure wave is generated at a position relatively close to the exhaust port 3. As a result, the output of the two-stroke engine E can be improved by efficiently introducing fresh air and exhausting combustion gas in accordance with the engine operating state.

Furthermore, the movable cylinder portion 37 to be driven by the servo motor 23 is relatively light, so the capacity of the servo motor 23 does not need to be increased.

In the first and second embodiments described above, the negative pressure generation position is changed by moving the downstream end of the guide tube 14.34 in order to improve the engine output. Driving the guide cylinder 14.34 disposed at the upstream end of the expansion chamber 6 so that the actual expansion angle of the exhaust gas from the pipe 5 to the expansion chamber 6 changes. There is also. That is, as shown in FIG. 1, by changing the position of the downstream end of the guide tube 14, the substantial spread angle of the exhaust gas from the exhaust pipe 5 to the expansion chamber 6 changes between α1 and α2, and As shown in FIG. 9, the position of the downstream end of the guide tube 34 changes, so that the exhaust pipe 5
The actual spread angle of the exhaust air from the expansion chamber 6 to the expansion chamber 6 is βl−β
Varies between 2. By changing the cough angle, the magnitude of the negative pressure wave at the upstream end of the expansion chamber 6 and the position of the negative pressure generating section can be changed, thereby improving the engine output.

Effects of the C1 Invention As described above, according to the first feature of the present invention, the downstream end of the u1 trachea is basically formed into a conical shape that increases in diameter toward the downstream side, and the upstream portion of the expansion chamber The upstream end of a guide tube disposed at the end is connected to the guide tube, and the guide tube is configured such that the downstream end can be moved along the exhaust flow direction, and the downstream end is moved according to the engine operating state. Since the guide cylinder is connected to the drive member, it is possible to change the position of negative pressure wave generation in the guide tube depending on the engine operating condition, and obtain stable output characteristics from engine high load conditions to low engine load conditions. , and the guide tube is relatively light.
Therefore, only a small driving force is required.

According to the second feature of the present invention, the downstream end of the exhaust pipe is basically formed into a conical shape with its diameter increasing toward the downstream side, and is disposed at the upstream end in the expansion chamber. The upstream end of the guide tube is connected to the guide tube, and the guide tube is configured to be able to vary the actual divergence angle of exhaust gas from the exhaust pipe to the expansion chamber, and is driven to change the divergence angle according to engine operating conditions. Since it is connected to a member, it is possible to change the negative pressure wave generation position and magnitude in the guide cylinder portion according to the engine operating condition, and obtain stable output characteristics from engine high load conditions to low engine load conditions. Moreover, the guide cylinder is relatively light, so the driving force can be small.

[Brief explanation of the drawing]

1 to 8 show a first embodiment of the present invention. FIG. 1 is an overall schematic diagram, FIG. 2 is an enlarged sectional view taken along the line ■-■ in FIG. 1, and FIG. 3 is a control diagram. A flowchart showing the control procedure of the means, FIG. 4 is a map for searching the atmospheric pressure correction coefficient, FIG. 5 is a map for searching the atmospheric temperature correction coefficient, and FIG. 6 is a diagram showing the map for searching the atmospheric temperature correction coefficient. FIG. 7 is a diagram showing a map for searching the operating amount, FIG. 7 is a diagram showing the map for searching the exhaust temperature correction coefficient, FIG. 8 is an output characteristic diagram, and FIGS. This shows the second embodiment, and the ninth
The figure is an overall schematic diagram, and FIG. 10 is a sectional view taken along the line X--X in FIG. 9. ]...Solinda Blosoku as the engine body, 3.
...Exhaust port, 5...Exhaust pipe, 6...Expansion chamber, 1
4゜34... Guide tube, 19... Drive member, 15...
・Exhaust flow direction, α1. α2, β1. β2... Spreading angle, E...2
Cycle engine Figure 2 Figure 3 Figure 6 Engine speed Figure 7 Figure 8 Engine speed Figure 4 Figure 5 Atmospheric temperature

Claims (2)

[Claims] (1) In an exhaust control device for a two-stroke engine, in which an upstream end of an exhaust pipe is connected to an exhaust port of an engine main body, and an expansion chamber is connected to a downstream end of the exhaust pipe, the downstream end of the exhaust pipe includes: The upstream end of a guide tube is connected to the guide tube, which is basically formed into a conical shape with its diameter increasing toward the downstream side and is disposed at the upstream end of the expansion chamber. What is claimed is: 1. An exhaust gas control device for a two-cycle engine, characterized in that the device is configured to be movable along the downstream end and is connected to a drive member to move the downstream end according to engine operating conditions. (2) In an exhaust control device for a two-stroke engine, in which an upstream end of an exhaust pipe is connected to an exhaust port of an engine main body, and an expansion chamber is connected to a downstream end of the exhaust pipe, the downstream end of the exhaust pipe includes: The upstream end of a guide tube is connected to the guide tube, which is basically formed into a conical shape with its diameter increasing toward the downstream side and is disposed at the upstream end of the expansion chamber. 1. An exhaust gas control device for a two-stroke engine, characterized in that the exhaust gas control device is configured to vary a substantial spread angle of exhaust gas, and is connected to a drive member to change the spread angle according to engine operating conditions.