JPH07279675A - Exhaust gas controller of two-cycle engine - Google Patents

Abstract

PURPOSE:To enable smooth acceleration from low speed to high speed without lowering output in switching of a valve. CONSTITUTION:In an exhaust gas controller of a two-cycle engine wherein a sub valve 4 is arranged in a sub exhaust hole 3 communicated with a main exhaust hole 1 formed on the peripheral wall of a cylinder, the sub exhaust hole 3 is formed in the inclined direction in relation to a horizontal surface perpendicular to a center shaft of a cylinder S, and the sub valve 4 is constituted of a slide-type valve capable of projecting and retreating into/from the sub exhaust hole 3 by being reciprocated in the horizontal surface by a driving means 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust control system for a two-cycle engine, and more particularly to a two-cycle engine mounted on a motorcycle or a small planing boat that requires high and smooth acceleration performance. Exhaust control device.

[0002]

2. Description of the Related Art In the case of a two-cycle engine, the air-fuel mixture is supplied from a crankcase to a combustion chamber through a scavenging port formed on a cylinder peripheral wall, and combustion gas is discharged after combustion at another portion of the cylinder peripheral wall. From the exhaust hole formed on the side toward the exhaust manifold side.

In recent years, with the intention of increasing exhaust efficiency over the entire range from the low speed range to the high speed range of such an engine, a sub exhaust hole is provided on the side of the main exhaust hole formed in the cylinder peripheral wall to rotate at a high speed. There is provided an exhaust control device capable of opening the auxiliary exhaust hole with respect to the main exhaust hole at times and closing the auxiliary exhaust hole at low speed rotation. Hereinafter, the valve for opening and closing the main exhaust hole will be referred to as a main valve (main valve in the claims), and the valve for opening and closing the auxiliary exhaust hole will be referred to as a sub valve (sub valve in the claims). . Conventionally, as the sub-valve, a switching cock, a butterfly valve, a ball valve or the like that is rotated according to the number of revolutions of the engine has been adopted.

However, such a structure has a low drive characteristic, which allows a compact drive mechanism, but has a low sealability, and since it is disposed in the flow path, the flow path resistance is large even when it is fully opened. Therefore, recently, a sub valve has been proposed which employs a slide type valve similar to the slide type main valve.

As shown in FIGS. 5 and 6, the sub-valve 51 is rotatably attached to an arm 54 formed on the same drive shaft 53 as the main valve 52 so as to interlock with the slide-type main valve 52. The rotation of the drive shaft 53 causes the drive shaft 53 to project and retract to the sub exhaust hole 55 via the arm 54. As a prior art, there is, for example, JP-A-5-133230.

[0006]

However, like the main valve 52, the sub-valve 51 having the above-described structure is inclined from above with respect to the horizontal plane orthogonal to the central axis of the cylinder S and protrudes into the sub exhaust hole 55. . On the other hand, generally, the auxiliary exhaust hole 55 extends horizontally from the opening 56 into the cylinder S for a little longer than the main exhaust hole 5 as shown in FIG.
7 extends slightly downward toward the opening 58 toward the opening 7, and the opening 56 of the auxiliary exhaust hole 55 is formed in the cylinder wall.
A scavenging hole 58 is formed in the lower part of the vicinity in the vicinity of the thin wall 59.

Therefore, the sub valve 51 is connected to the sub exhaust hole 5
When it is attempted to insert and close the opening 56 to the inner peripheral surface of the cylinder to the end of the cylinder 5, it is necessary to form the horizontal portion of the auxiliary exhaust hole 55 by inclining from the top to the bottom. Then, the partition wall portion 59 between the sub exhaust hole 55 and the scavenging hole 58 is formed.
Becomes extremely thin, and durability against gas pressure is poor, and erosion is generated by a high-speed gas flow, resulting in poor durability. For this reason, at present, the sub-valve is only projected to a position slightly retracted from the inner peripheral surface of the cylinder. As a result, a concave portion is formed on the inner peripheral surface of the cylinder, which impairs smooth intake and combustion of the air-fuel mixture in the cylinder, making it impossible to improve the output during low-speed rotation.

The present invention has been made in order to solve the above problems, and the inner wall surface of the auxiliary exhaust hole can be extended to the inner peripheral surface of the cylinder without thinning the partition wall between the auxiliary exhaust hole and the scavenging hole. It is an object of the present invention to provide an exhaust control device for a two-cycle engine, which includes a sub-valve capable of fully closing the sub-exhaust hole by inserting the exhaust valve up to the opening of the above, and which does not reduce the output even when switching.

[0009]

In the exhaust control system for a two-cycle engine of the present invention, a main valve is provided in a main exhaust hole formed in a cylinder peripheral wall, and a sub-exhaust hole communicates with the main exhaust hole. In an exhaust control device for a two-cycle engine, in which a valve is provided and the opening timing and opening area of the exhaust hole can be adjusted by the both valves, a horizontal plane in which the auxiliary exhaust hole is orthogonal to a central axis of a cylinder. Is formed in a direction inclined with respect to the sub-valve, and the sub-valve is configured as a slide-type valve that can be projected / retracted to / from the sub-exhaust hole by being reciprocally moved in the horizontal plane by a driving means. .

The drive means may be composed of a governor mechanism that is operated by the rotation of the engine and a transmission means that transmits the operation of the governor mechanism to the sub valve. In this case, the transmission means is the governor. If a gear that is rotated by the driving force from the mechanism and a rack member that meshes with the gear and is movable in the moving direction of the sub valve are used, the device has a simple mechanism and is highly reliable.

The drive means is composed of an electric motor which is controlled in accordance with the rotation of the engine, and a transmission means which transmits the operation of the electric motor to the sub-valve. It is also possible to comprise a gear that is rotated by the driving force of and a rack member that meshes with the gear and that is movable in the moving direction of the sub-valve. The rotation speed can be finely controlled or can be controlled without being directly related to the rotation speed of the engine, and the device has high reliability.

The driving means is provided with a detent mechanism arranged between the rotating portion of the transmitting means and the fixed side of the engine, and the rotating shaft for causing the detent mechanism to perform the projecting / retracting operation of the sub valve. And a cam plate having at least one engaging concave portion disposed on the side, and the engaging concave portion of the cam plate when the base portion is embedded in the engine fixed side so as to be retractable by spring means and the auxiliary valve is projected. If the ball is engaged with the ball, the output can be further improved.

The detent mechanism is provided with
Retracting operation of the sub valve by engaging the engaging portion formed on the rotating shaft side for performing the retreating operation and the engaging portion when the base portion is fixed to the fixed side of the engine and the sub valve is projected. And a spring means for giving resistance to.

When the drive means is composed of an electric motor which is controlled in response to the rotation of the engine, when the auxiliary valve is in a protruding state, it is formed so as to give a rotational torque in the protruding direction of the auxiliary valve to the electric motor. The blocking means can be constituted by the provided electric circuit.

A through hole is formed in the support shaft of the gear, and when the gear rotates so as to project the sub valve and close the sub exhaust hole, the through hole communicates the resonance chamber with the main exhaust hole. If the gear is configured to block the communication between the resonance chamber and the main exhaust hole when the gear is rotated so as to retract the auxiliary valve and open the auxiliary exhaust hole, the output is further increased. It is possible to obtain an engine that can smoothly blow up.

The horizontal plane in this specification is not used in a strict sense, but is simply used as a plane orthogonal to the central axis of the cylinder.

[0017]

According to the exhaust control system for a two-cycle engine of the present invention (hereinafter, simply referred to as an exhaust system), the sub-valve is horizontally inserted along the horizontal portion of the sub-exhaust hole to the inner peripheral surface of the cylinder. be able to. That is, even if the partition wall between the sub-exhaust hole and the scavenging hole is made thin, the sub-exhaust hole can be fully closed, and no irregularities are formed on the inner peripheral surface of the cylinder. It is possible to improve the output.

Further, in the exhaust device provided with the detent mechanism, during the switching operation of the sub-valve, that is, when the sub-valve projects and closes the sub-exhaust hole to the retracting operation (opening operation). Even if a high pressure due to combustion acts from inside the cylinder, the backward movement of the sub-valve due to the high pressure is prevented, so that the desired valve operation can be performed accurately. As a result, the desired opening timing and opening area can be obtained even in the rotation range corresponding to the switching of the valve, and the output of the engine does not decrease at the switching of the valve.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Exhaust devices according to embodiments of the present invention will be described in more detail below with reference to the drawings.

FIG. 1 is a plan sectional view of an exhaust hole portion of a cylinder showing a state where a sub-valve is projected in an embodiment of the exhaust system of the present invention, and FIG. 2 is a cylinder showing a state where a sub-valve is projected in the exhaust system of FIG. 3 is a partial cross-sectional side view of the exhaust hole portion of FIG. 3, FIG. 3 is a partial cross-sectional side view of the exhaust hole portion of the cylinder showing a state where the sub-valve of the exhaust device of FIG. 1 is retracted, and FIG. It is explanatory drawing which shows the detent mechanism in an apparatus.

1 to 3, 1 is a main exhaust hole, 2 is a main valve provided in the main exhaust hole 1, 3 is a sub exhaust hole, 4 is a sub valve provided in the sub exhaust hole 3, Reference numeral 5 is a drive means for driving the sub-valve 4, 6 is a detent mechanism, and 7 is a resonance chamber for improving the engine output at low speed rotation. In FIG. 2, in order to clarify the configuration of the sub valve 4, the main exhaust hole 1 and the main valve 2 are shown by a chain double-dashed line.

The main exhaust hole 1 has a tip open to the peripheral wall of the cylinder S and a base end extending toward the exhaust manifold.
At the upper end of the main exhaust hole 1 in the vicinity of the cylinder S, the main valve 2 is slidably arranged with respect to the main exhaust hole 1 so that the upper surface contacts the ceiling surface of the main exhaust hole 1. There is. At the base end portion (right end in FIG. 1) of the main valve 2, a pivot shaft 2a forming a part of the transmission means of the drive means 5 is provided in a protruding manner. The tip end of a lever 8 that constitutes a part is locked, and the pivotal movement of the lever 8 around a pivot shaft 9 causes the pivot shaft 2 to rotate.
When a is pushed toward the cylinder S side, the main valve 2 is projected or retracted toward the cylinder S side. Thus, the drive means 5 of the sub-valve doubles the drive source (such as a governor mechanism (not shown)) and the rotary shaft 9 among the constituent elements thereof for the main valve 2. The rotating shaft 9 is configured to rotate according to the number of rotations by a crank shaft of an engine (not shown) and a governor mechanism that interlocks with the crank shaft.

As shown in FIGS. 1 and 3, the sub-exhaust holes 3 are formed on both sides of the main exhaust hole 1, and their tips open to the peripheral wall of the cylinder S, and a small area 3a at the tip portion (see FIGS. 2) extends horizontally, and then is inclined downward so that the base end communicates with the main exhaust hole 1. A scavenging hole 10 is opened below the opening 3b of the auxiliary exhaust hole 3 to the peripheral wall of the cylinder S. That is, the horizontal region 3a of the auxiliary exhaust hole 3
Below this, a scavenging hole 10 is formed via a partition wall 11 inside the cylinder wall.

As is apparent from FIGS. 1 and 3, the sub-valve 4 is inserted and arranged from both sides of the main valve 2 toward the cylinder S at an angle to each other, as shown in FIG. It is capable of reciprocating horizontally. That is, the insertion hole 12 of the sub valve 4 is formed so as to communicate with the horizontal region 3 a of the sub exhaust hole 3 from outside the cylinder S. Therefore, the sub valve 4
The tip end portion of is inserted into the horizontal region 3a of the auxiliary exhaust hole 3 and can reach a position where it coincides with the inner peripheral surface of the cylinder S. By doing so, the operation of fully closing the sub exhaust hole 3 (see FIG. 1) becomes possible. Of course, the partition wall portion 11 is not thinned as in the conventional case.

The sub-valve 4 is provided with teeth 13 as a rack along its longitudinal direction, and a gear 14 rotatably around its own axis and arranged parallel to the axis of the cylinder S. Meshes with. The gear 14 is rotated by a rack member 16 that meshes with a pinion gear 15 fixed to the rotating shaft 9 and reciprocates. Thus, the sub-valve 4 and the main valve 2 have the same rotary shaft 9
Since it is driven by, it will be linked. Of course, it is also possible to shift the operation timing of both valves 2 and 4 by partially forming the teeth of the pinion gear 15 instead of forming the entire circumference.

Further, the support shaft portion 1 below the gear 14
A through hole 14a is formed in 4b. This through hole 14
Reference character a forms a part of a communication passage 7a between the auxiliary exhaust hole 3 and the resonance chamber 7, and the support shaft portion 14b of the gear 14 also serves as a switching valve for the communication passage 7a. There is.
When the sub-valve 4 is in a position to close the sub-exhaust hole 3, the through hole 14a communicates the sub-exhaust hole 3 with the resonance chamber 7 (FIG. 1), and the sub-valve 4 rotates by the gear 14 to cause the sub-exhaust hole to rotate. When retracting to the position where 3 is opened, the support shaft portion 14b closes the communication passage 7a (FIG. 3). In this way, the action of the sub-valve 4 and the action of the resonance chamber 7 preferably cooperate with each other, so that the output is effectively improved during low-speed rotation.

The rotating shaft 9 (see FIGS. 1 and 3)
In the right side of the pinion gear 15)), a cam plate 6a constituting the detent mechanism 6 is fixedly provided, and the engagement recess 6b (see FIG. 4 (a) is formed on the peripheral surface of the cam plate 6a. ), 4 (b)) are formed. A ball 6c is arranged on the cylinder S side of the engine so that the head contacts the peripheral surface of the cam plate 6a. The ball 6c is inserted from below from the coil spring 6d into the cylinder 6e by the cam plate 6a. Pressed to the side. The coil spring 6
Instead of d, another spring such as a leaf spring or a disc spring may be appropriately selected and used. In this exhaust device, the driving force of the governor mechanism (not shown) is set to be larger than the resistance force due to the engagement between the engagement recess 6b and the ball 6c. This setting can be made, for example, by increasing the weight of the weight of the governor mechanism or by increasing the length of the lever 8 to increase the boosting action. Further, the sum of the resistance force in the opposite direction of the governor mechanism and the resistance force causes the high pressure due to the combustion in the cylinder to be the main valve 2 and the sub valve 4.
It is set to be larger than the force acting on. In the exhaust device in which the drive timings of the main valve 2 and the sub valve 4 are different, if two engaging recesses are formed on the peripheral surface of the cam plate 6a, the closed positions of both valves 2 and 4 will be different. The action of the detent mechanism is performed.

In FIG. 2, reference numeral 17 is a cap valve for covering the lower surface of the main valve 2 in the retracted state of the main valve 2 to make the upper surface of the main exhaust hole 1 smooth. The cap valve 17 swings around the swing shaft 17a in conjunction with the protrusion / retraction movement of the main valve 2 to cover the upper surface of the main exhaust hole 1 as described above (see FIG. 2). Alternatively, it functions to expose the tip of the main valve 2 (see FIG. 1).

According to the exhaust device equipped with such a detent mechanism, it is possible to avoid the phenomenon that the output is lowered in the exhaust valve switching range as in the conventional case.

That is, in the region from the low-speed region to the medium-speed region of the engine, as shown in FIG. 1, the sub-exhaust hole 3 is closed by the sub-valve 4, and the main valve 2 has its tip almost at the peripheral wall of the cylinder. It projects to the same position (to be exact, slightly retracted position). And in this state,
As shown in FIG. 4 (a), the engaging recess 6b of the cam plate 6a fixed to the rotating shaft 9 for operating both valves 2 and 4 is shown.
Is engaged with the head of the ball 6c. Therefore, in this state, the air-fuel mixture burns in the cylinder S, and a high pressure in a direction (see arrow X in FIGS. 1 and 2) for retracting the valves 2 and 4 acts on the tips of the valves 2 and 4. However, as a result of the addition of the resistance force of the driving means and the resistance force of the engagement of the detent mechanism 6, both valves 2 and 4 do not retract. Conversely speaking, as described above, the total resistance force obtained by adding the resistance force in the reverse direction by the driving means 6 and the resistance force by the engagement of the detent mechanism 6 is applied to the high pressure acting on the tips of both valves 2, 4. It is necessary to set it larger than the force caused by. Then, when the engine speed reaches the medium speed range, the governor mechanism rotates the rotating shaft 9 and the two valves 2,
4 is retracted, the driving force of the governor mechanism overcomes the resistance force due to the engagement between the engagement recess 6b and the ball 6c, and as shown in FIG. Can be retracted (see also Fig. 4 (b)).

As described above, the pinion gear 15
Teeth of the cam plate 6a are partially formed instead of the entire circumference to form two engaging recesses on the peripheral surface of the cam plate 6a.
In the exhaust device configured to shift the operation timing of No. 4, the main valve 2 moves backward (at this time, the sub-valve 4
Does not retreat), the ball 6c engages with the engaging recess 6b at another location, and the same action as described above is achieved.

Therefore, in the two-cycle engine provided with this exhaust system, the engine output smoothly rises even in the middle speed range of the engine in which one or both of the main valve 2 and the sub valve 4 are switched, and the comfort is improved. You can get a great acceleration.

Further, in place of the detent mechanism of the above-mentioned embodiment, although not shown, a protrusion for engagement is formed on the valve body or the above-mentioned cam plate and the spring means (for example, The detent mechanism may be formed by a leaf spring, or a leaf spring, a coil spring, or a disc spring with a contact piece attached to the tip).

In the above embodiment, both valves 2,
4 was driven by the governor mechanism, but an electric motor can be used instead of this governor mechanism. In this case, a pulley or sprocket is fixedly mounted on the rotating shaft 9 and a wire is attached to this pulley. An electric motor can be used to actuate both valves, via the sprocket or via a chain and a drive sprocket. By using the electric motor in this way, the control amount of both valves can be obtained electrically more freely than the governor mechanism with respect to the engine speed, that is, without being directly related to the engine speed. It is possible to further improve the output of the engine or obtain an arbitrary output characteristic with respect to the engine speed. Further, even when an electric motor is used, the detent mechanism can be used as it is, but instead, torque in the reverse direction (which means torque in the direction to close the valve) may be applied to the electric motor. .

If the main valve and the sub-valve can be operated by independent electric motors, the output of the engine can be further improved.

[0036]

According to the present invention, since the exhaust hole can be preferably fully closed, not only can a high and smooth acceleration performance be obtained in the entire range from the low speed region to the high speed region, but also the scavenging hole and the auxiliary exhaust gas can be obtained. A partition wall between the holes can be secured. Therefore,
In a motorcycle or a small planing boat equipped with a two-cycle engine equipped with this exhaust control device, good acceleration is guaranteed.

[Brief description of drawings]

FIG. 1 is a plan view of an exhaust hole portion of a cylinder, showing a partial cross section, showing a configuration of an exhaust device according to an embodiment of the present invention in a state where a sub valve is projected.

FIG. 2 is a side view of an exhaust hole portion of a cylinder, which is a partial cross-section, showing the configuration of the exhaust device shown in FIG. 1 in a state where a sub valve is projected.

FIG. 3 is a plan view of an exhaust hole portion of a cylinder, which is a partial cross-section, showing the configuration of the exhaust device shown in FIG. 1 in a state where a sub valve is retracted.

FIG. 4 is an explanatory diagram showing an example of a detent mechanism in the exhaust system of FIG.

FIG. 5 is a partially sectional plan view showing an example of a conventional exhaust device.

6 is a side view showing a partial cross section of the exhaust device of FIG.

[Explanation of symbols]

 1 ... Main exhaust hole 2 ... Main valve 3 ... Sub exhaust hole 4 ... Sub valve 5 ... Driving means 6 ... Detent mechanism

Claims (7)

[Claims] 1. A main valve is provided in a main exhaust hole formed in a cylinder peripheral wall, a sub valve is provided in a sub exhaust hole communicating with the main exhaust hole, and the opening timing of the exhaust hole is provided by the both valves. In the exhaust control device for a two-cycle engine, the auxiliary exhaust hole is formed in a direction inclined with respect to a horizontal plane orthogonal to the central axis of the cylinder, and the auxiliary valve is driven. The exhaust control device for a two-cycle engine according to claim 1, wherein the exhaust control device is configured as a slide valve that can reciprocate in the horizontal plane by means to project and retract in the auxiliary exhaust hole. 2. The drive means includes a governor mechanism that operates by rotation of an engine and a transmission means that transmits the operation of the governor mechanism to the sub-valve, and the transmission means includes the governor mechanism. 2. The exhaust control device for a two-cycle engine according to claim 1, further comprising: a gear that is rotated by the driving force of the gear and a rack member that meshes with the gear and is movable in the moving direction of the sub valve. . 3. The drive means comprises an electric motor controlled in response to engine rotation, and a transmission means for transmitting the operation of the electric motor to the sub valve, the transmission means comprising: The two-cycle engine according to claim 1, comprising a gear that is rotated by a driving force from the electric motor, and a rack member that meshes with the gear and is movable in a moving direction of the sub valve. Exhaust control device. 4. The drive means has a detent mechanism arranged between the rotating portion of the transmission means and the fixed side of the engine, and the detent mechanism controls the projecting / retracting operation of the auxiliary valve. A cam plate which is disposed on the side of the rotating shaft and which has at least one engaging recess, and a cam on the fixed side of the engine when the base is supported by spring means so as to be retractably embedded and the auxiliary valve is projected. The exhaust control device for a two-cycle engine according to any one of claims 1 to 3, wherein the exhaust control device comprises a ball that engages with an engaging recess of the plate. 5. The detent mechanism is provided with an engaging portion formed on a rotation shaft side for performing a projecting / retracting operation of the sub valve, and a state in which a base portion is fixed to a fixed side of the engine and the sub valve is projected. 4. The spring according to claim 1, further comprising a spring means that engages with the engaging portion and provides resistance to the backward movement of the sub valve. Exhaust control device for cycle engine. 6. The drive means is composed of an electric motor that is controlled in response to engine rotation, and when the auxiliary valve is in a protruding state, applies a rotational torque in the auxiliary valve protruding direction to the electric motor. 2. The exhaust control device for a two-cycle engine according to claim 1, further comprising a blocking means constituted by an electric circuit formed as described above. 7. A through hole is formed in a support shaft of the gear, and when the gear rotates so as to project the sub valve and close the sub exhaust hole, the through hole causes the resonance chamber and the main exhaust to flow. The support shaft is configured to block communication between the resonance chamber and the main exhaust hole when the gear rotates so as to communicate with the hole, and the gear rotates to retract the sub valve and open the sub exhaust hole. An exhaust control device for a two-cycle engine according to claim 2.