JPH03260321A - Control valve driving device of two-cycle engine - Google Patents

Abstract

PURPOSE:To make a full body of an engine compact by arranging a transmission mechanism which connects an arm which openly and closely drives an exhaust air control valve to a control valve driving mechanism arranged at a crank case, at a dead space between a pivotal shaft of the arm and a cylinder bore. CONSTITUTION:At an inner wall of a cylinder bore 5a formed at a cylinder block 5, an exhaust port 35 opened and closed by a piston 33 which reciprocates in the inside is opened. At the exhaust port 35, the port opening area is variably controlled by a control valve 36r. The pivotal shaft 43 adapted to support an arm member 44 which opens or closes the control valve 36r, is arranged in parallel to the tangential ione of a cylinder bore 5a. A transmission mechanism 29 which connects a control valve driving mechanism(not shown) arranged at a crank case 4 to the arm member 44 is arranged along the cylinder bore 5a at the space between the pivotal shaft 43 and the cylinder bore 5a.

Description

Detailed Description of the Invention A1 Object of the Invention (1) Industrial Application Field The present invention has an exhaust port opened and closed on the inner wall of a cylinder bore formed in a cylinder block, which is opened and closed by a piston that reciprocates within the cylinder bore. The present invention relates to a control valve drive device for a two-stroke engine, which includes a control valve provided in the exhaust port to variably control the opening area of the exhaust port.

(2) Prior Art The control valve drive system for the two-stroke engine described above is already known, as described in, for example, Japanese Patent Application Publication No. 192913/1983. According to such a control valve drive device, when the engine is in a low-speed operating range including idling, it is possible to reduce the opening area of the exhaust port to prevent fresh air from blowing through, and when the engine is in a medium- to high-speed operating range. If possible, it will be possible to increase the opening area of the exhaust port and improve the output.

(3) Problems to be Solved by the Invention However, in the conventional control valve drive device described above, the transmission mechanism that transmits driving force to the control valve largely protrudes to the side of the cylinder block, which increases the size of the entire engine. However, there was a problem in that it caused problems when installed in small vehicles such as motorcycles.

The present invention was made in view of the above-mentioned circumstances, and an object of the present invention is to make the entire engine compact by rationally laying out the transmission mechanism of the control valve provided in the control valve drive device of a two-stroke engine. shall be.

B1 Structure of the Invention (1) Means for Solving the Problems In order to achieve the above object, the present invention provides an exhaust port that is opened and closed on the inner wall of a cylinder bore formed in a cylinder block by a piston that reciprocates within the cylinder bore. In a control valve drive device for a two-stroke engine, the control valve drive device for a two-cycle engine is provided with a control valve that opens and variably controls the opening area of the exhaust port, and an arm member that is connected to the control valve and opens and closes the control valve. A swingably supported pivot is disposed parallel to the tangent line of the cylinder bore, and a transmission mechanism connecting the control valve drive mechanism provided in the crankcase and the arm member is connected to the space between the pivot and the cylinder bore. It is characterized in that it is arranged along the cylinder bore.

(2) Function According to the above-mentioned feature, the driving force of the control valve drive mechanism provided in the engine crankcase is transmitted to the arm member via the transmission mechanism, and is connected to the arm member that swings around the pivot opening. The control valve is driven to variably control the opening area of the exhaust port opening into the inner wall of the cylinder body T. At this time,
Since the transmission mechanism is disposed along the dead space formed between the cylinder bore and the pivot that pivots the arm member, the transmission mechanism prevents the entire engine from increasing in size.

(3) Examples Hereinafter, the present invention will be described in detail based on the drawings.

FIG. 1 is an overall side view of a motorcycle equipped with an engine E equipped with a control valve drive device according to an embodiment of the present invention. A front wheel Wf is pivoted on the lower end of a front fork 2 supported by the front part of the vehicle body frame F and rotated from side to side by a handle 1, and a rear fork 3 is supported at the rear of the front fork 2 so as to be swingable up and down. A rear wheel Wr connected to and driven by the engine E is mounted on a shaft at the rear end of the vehicle. The engine E is a single-cylinder two-stroke engine, and as is clear from FIG. 6 is approximately 36 along the front surface of the crankcase 4 located below.
After being bent by 0°, a muffler 7 extends rearward through the right side of the cylinder block 5 and is provided at the rear end of the vehicle body frame F.
is connected to.

3'5th! J is a horizontal cross-sectional view of the crankcase 4, showing a control valve drive mechanism 8 that drives a control valve, which will be described later, provided in the exhaust boat of the engine E. The control valve drive mechanism 8 is housed in a housing B4a integrally connected to the front right side of the crankcase 4 of the engine E, and a pair of ball bearings 9. It is provided with a governor 13 that is interlocked with a water pump 12 for circulating cooling water, which is driven by a crankshaft 11 supported via an IO. The governor 13 is fixed to a pump shaft 16 supported in the storage part 4a via a pair of ball bearings 14.15, and has a ring gear 18a on its outer periphery that meshes with an output gear 17 fixed to the end of the crankshaft 11. A bowl-shaped lamp plate 18 and this lamp plate 1
a slide plate 19 slidably supported on the pump shaft 16 so as to face the recess of the lamp brake 1);
8 and a centrifugal weight 20 disposed between the slide plate 19 so as to be movable in the radial direction. An intermediate portion of a lever 23 is pivotally supported on a bin 21 installed inside the storage portion 4a, and a fork portion 23a formed at one end of this lever 23 is connected to the pressing surface 1 of the slide plate 19.
It is in contact with 9a. Pump shaft 1 with the bottle 21 in between
A slide member 26 biased by a spring 25 is slidably engaged in a guide groove 24 formed parallel to the guide groove 6, and a fork portion 23b formed at the other end of the lever 23 is in contact with the stepped portion 26a of the slide member 26. ing. An arm 28 provided at the lower end of a drive shaft 27 rising from the housing portion 4a of the crankcase 4 toward the cylinder block 5 is engaged with a shaft portion 26b formed at the end of the slide member 26. Therefore, as the rotational speed of the crankshaft 11 of the engine E gradually increases, the centrifugal weight 20 of the governor 13 moves radially outward along the ramp plate 18 and presses the slide plate 19 leftward in the figure. As a result, lever 2
3 swings clockwise to press the slide member 26 to the right against the spring 25, and rotates the drive shaft 27, which is engaged with the shaft portion 26b of the slide member 26 through the T-arm 28, by a predetermined angle.

As shown in FIGS. 4 to 6, a transmission mechanism 29 for transmitting the driving force of the control valve drive mechanism 8, that is, the rotation of the drive shaft 27 to the control valve described later, is connected to the upper part of the crankcase 4. A horizontal shaft 30 is arranged horizontally at the front lower part of the cylinder block 5, and a vertical shaft 3 is connected to the left end of the horizontal shaft 30 and stands up vertically on the left side of the cylinder block 5.
1 (see Figure 6). An eccentric pin 32 provided at the upper end of the drive shaft 27 is engaged with a groove 30a formed at the right end of the horizontal shaft 30, and as the drive shaft 29 rotates, the horizontal shaft 30 is moved through the eccentric pin 32. Moves back and forth from side to side. A rack 30 formed at the left end of this horizontal shaft 30
b is a pinion 31a formed at the lower end of the vertical shaft 31;
are in mesh with each other, so that the movement of the horizontal shaft 30 that reciprocates left and right becomes a reciprocating rotational motion and is transmitted to the vertical shaft 31.

As shown in FIGS. 7 to 10, a cylinder bore 5a into which a piston 33 slides is formed inside the cylinder block 5, and a plurality of scavenging ports 34 and one exhaust port 35 are opened on the inner surface of the cylinder bore 5a. There is. A control valve 36 is attached to the exhaust port 35 so as to be vertically movable in order to variably control the height of its upper edge. A sleeve 40 to which a driving force is transmitted via a torsion spring 38 and an interlocking plate 39 of a lost motion mechanism 37 that absorbs excessive rotation of the vertical shaft 31 is fitted into the upper end of the vertical shaft 31. , a worm gear 40a provided on this sleeve 40 meshes with a worm wheel 43H provided on one end of a pivot 43 disposed parallel to the horizontal shaft 30 via a pair of ball bearings 41, 42 above the cylinder block 5, This axis 43
A bifurcated arm 44a of an arm member 44 fixedly engaged with the control valve 36. The transmission mechanism 29, ie, the horizontal shaft 30 and the vertical shaft 31, are shown in FIGS. 7 and 8.
As is clear from the figure, it is disposed along the dead space formed between the pivot 42 of the arm member 44 that drives the control valve 36 and the cylinder bore 5a, and due to the above-described layout of the transmission mechanism 29, the engine E Efforts have been made to reduce the size. Further, the transmission mechanism 29 and the lost motion mechanism 37 are covered by a removable cover 5b provided on the left side of the cylinder block 5, that is, on the opposite side to the exhaust pipe 6 disposed along the right side of the vehicle body.
It is designed so that maintenance can be performed without removing the exhaust pipe 6.

Next, the structure of the control valve 36 will be explained in detail with reference to FIG. 11. At the front of the cylinder block 5, an exhaust port 35 that opens into the inner surface of the cylinder bore 5a is formed diagonally downward toward the front, and the upper part of the exhaust port 35 is formed with a through hole 45 that opens into the inner surface of the cylinder bore 5a. is formed in the radial direction of the cylinder bore 5a. Inside the through hole 45, the control valve 36, the pivot 42,
A support member 46 that supports the arm member 44 is inserted from the outside as a unit and fixed to the cylinder block 5 with bolts 47. An inclined wall surface 46a is formed at the lower end of the support member 46, and when the support member 46 is inserted into the through hole 45, the wall surface 46a constitutes a part of the earthen wall of the exhaust port 35. . As is clear from FIGS. 8 and 10, the inside of the exhaust port 35 has a vertical reinforcing wall 48 extending in the radial direction of the cylinder bore 5a.
It is divided into two parts, left and right. The lower end of the reinforcing wall 48 is connected to the cylinder block 5 at the lower surface 35a of the exhaust port 35.
and its upper end is connected to the upper surface 45 of the through hole 45.
It is connected to the cylinder block 5 at point a. The upper part of the reinforcing wall 48 is fitted into a slot 7) 46b formed vertically in the support member 46 inside the through hole 45.

The control valve 36 consists of two members, a right valve body 36r and a left valve body 361, which are formed symmetrically with respect to the reinforcing wall 48, and both valve bodies 36r and 361 have their guide portions 36a formed in the support member 46. It is engaged with the guide groove 46c and supported so as to be vertically slidable. Each valve body 36r, 361 includes an arcuate valve portion 36b that smoothly connects to the cylinder bore 5a and slides on the piston 33, and the valve portion 36b and the guide portion 36a are integrally connected via a connecting portion 36c. There is. A sealing surface 36b formed on the back surface of the valve portion 36b.
1 and a sealing surface 46 formed at the tip of the support member 46 (l slidingly contacts each other, both valve bodies 36r.

36I! Airtightness is ensured when the support member 46 slides up and down relative to the support member 46. Further, the T-shaped arm 44a of the arm member 44 is inserted into the hole 36al formed in the guide portion 36a.
The tip end is inserted, and the movement of the arm member 44 causes both valve bodies 36
r, 361.

And both valve bodies 36r, 364! The fully open position where the valves 36r and 361 are raised to the highest level is regulated by the stepped portions 36b2 formed on the valve portions 36'b of the valve bodies 36r and 361 coming into contact with the step R46e formed on the support member 46, so that both the valve bodies 36r and 361 are The lowest fully closed position is the boss portion 44b of the arm member 44.
The stopper 44c protruding from the stopper bolt 4g comes into contact with the stopper bolt 4g, whereby the stopper 44c is regulated.

Next, the operation of the embodiment of the present invention having the above-described configuration will be explained.

When the engine E is currently in a low speed operating range including idling, as shown in FIG.
Both valve bodies 36r are located at the position indicated by the solid line in contact with the valve bodies 36r. 361 has its guide portion 36a guided by the guide groove 46c of the support member 46 and has been lowered to the fully open position shown by the solid line. In this state, the opening period of the exhaust boat 35 becomes the shortest, reducing the blow-through of fresh air introduced into the cylinder bore 5a from the scavenging boat 34 to the exhaust port 35, and suppressing the increase in harmful compounds in the exhaust gas.

During the process in which the rotational speed of the engine E passes through the medium-speed operating range and reaches the high-speed operating range, as shown in FIG. Lever 23, shaft portion 26b1 of slide member 26, drive shaft 27, horizontal M30S and vertical #13
1 moves and rotates in the direction of the arrow, respectively, and the arm member 4
4 swings upward. As a result, the control valve 36 rises to the fully open position shown by the chain line in FIG. The effective aperture area of is the maximum. As a result, a large amount of exhaust gas generated in the middle and high speed range of the engine E can be efficiently removed from the exhaust port 3.
5, making it possible to increase output by improving exhaust efficiency. In addition, after the control valve 36 reaches the fully open position in the process of the engine E moving from the medium-speed operating range to the high-speed operating range, the vertical shaft 31 of the transmission mechanism 29 connected to the control valve drive mechanism 8 rotates excessively. However, the rotation is due to the lost motion mechanism 37
It is not absorbed in the control valve 36 and transmitted to the control valve 36.

When high-temperature exhaust gas passes through the exhaust port 35 due to the operation of the engine E, the reinforcing wall 48 that partitions the exhaust port 35 into left and right sides is heated by the exhaust gas, and the heat is transferred to the exhaust port 35 to which the lower end of the reinforcing wall 48 is connected. A lower surface 35a;
It escapes into the cylinder block 5 from the upper surface 45a of the through hole 45 to which the upper end is connected. At this time, since the outer end of the cylinder bore 58 of the reinforcing wall 48 in the radial direction extends to the outside beyond the outer edge of the wall surface 46a formed on the lower surface of the supporting member 46 (the reinforcing wall 48 in FIG.
46b of the support member 46 into which the reinforcing wall 48 fits in), the cylinder bore 5 of the reinforcing wall 48
a An extremely large width in the radial direction is ensured. Thereby, heat is efficiently transferred from the reinforcing wall 48 to the cylinder block 5, and the strength and durability of the reinforcing wall 48 are improved.

Although the embodiments of the present invention have been described above in detail, the present invention is not limited to the embodiments described above, and various small design changes may be made without departing from the scope of the invention described in the claims. It is possible to do so.

For example, in the embodiment, a case where the present invention is applied to an upright two-stroke engine has been described, but it is obvious that the present invention can also be applied to other types of engines such as a horizontal two-stroke engine.

C1 Effects of the Invention As described above, according to the present invention, the transmission mechanism that connects the arm that opens and closes the control valve that variably controls the opening area of the exhaust port and the control valve drive mechanism provided in the crankcase is configured as described above. Since the arm member is arranged along the dead space formed between the axis parallel to the tangent of the cylinder bore and the cylinder bore in order to swingably support the arm member, the transmission mechanism is compact without protruding significantly from the cylinder block. As a result, it can contribute to downsizing of the entire engine.

[Brief explanation of drawings]

FIG. 1 is an overall side view of a motorcycle equipped with an engine equipped with a control valve drive device according to an embodiment of the present invention, and FIG. 2 is a view taken along the line ■-■ in FIG. A cross-sectional view of the crankcase taken along the line ■-■ in Figure 1, and Figure 4 is a cross-sectional view taken along the line T in Figure 3.
A cross-sectional view taken along the line V-rV, FIG. 5 is a cross-sectional view taken along the line V-v in FIG.
Fig. 6 is a perspective view showing the driving force transmission path from the control valve drive mechanism to the transmission mechanism, Fig. 7 is a partial vertical sectional view of the cylinder block taken along the line ■-■ in Fig. 8, and Fig. 8 is ■－■
9 is a longitudinal sectional view of the cylinder block taken along the line IX--IX in FIG. 8, and FIG. 10 is a longitudinal sectional view of the cylinder block taken along the line XX in FIG. FIG. 11 is an exploded perspective view of the control valve and its surroundings.

Claims (1)

[Claims] The cylinder bore (5) formed in the cylinder block (5)
an exhaust port (35) opened and closed by a piston (33) reciprocating within the cylinder bore (5a) on the inner wall of the cylinder a);
is opened, and the exhaust port (35) is connected to the exhaust port (35).
5) A control valve drive device for a two-stroke engine comprising a control valve (36) that variably controls the opening area of the control valve (36), comprising: an arm member connected to the control valve (36) to open and close the control valve (36); (44) is disposed parallel to the tangent line of the cylinder bore (5a), and the control valve drive mechanism (8) provided in the crankcase (4) and the arm A two-stroke engine, characterized in that a transmission mechanism (29) for connecting the member (44) is disposed in a space between the pivot shaft (43) and the cylinder bore (5a) and along the cylinder bore (5a). control valve drive device.