JP2887877B2 - Engine intake control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intake control device provided with an intake control valve for reducing the sectional area of an intake passage when the engine is rotating at a low speed or the like. The present invention relates to an improvement in the shape and arrangement of the intake control valve, which can be gradually narrowed.

[0002]

2. Description of the Related Art An intake control system for an engine increases the flow velocity even when the intake air amount is small, such as during low-speed rotation or low-load operation, so that intake air is blown into the combustion chamber in a directional manner to stabilize lean air-fuel ratio combustion. This is a device for improving the fuel consumption rate (hereinafter referred to as fuel efficiency). Conventionally, as such an intake control device, for example, Japanese Patent Publication No. 59-576
As disclosed in Japanese Patent Application Publication No. 7, the intake control plate is arranged to be able to undulate near the intake valve opening of the intake passage, and the control plate is raised during low-speed rotation or low-load operation so as to reduce the intake passage area. There is something.

[0003]

However, in the above-mentioned conventional intake control device, the control plate remains in the intake passage even when it is fully opened due to the structure of raising and lowering the control plate. However, there is a problem that the intake resistance increases when the intake air amount is large. Further, in the above-described conventional apparatus, since the structure is such that only a part of the intake passage is narrowed, the sectional area of the intake passage changes rapidly, which is disadvantageous in improving low-speed torque and low-speed fuel consumption.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and can avoid the problem of the intake resistance at the time of high-speed operation and the like, and can avoid the rapid change of the cross-sectional area of the intake passage so that the low-speed torque and the low-speed It is an object of the present invention to provide an intake control device for an engine that can improve the fuel efficiency at the time.

[0005]

According to the present invention, there is provided an intake system for an engine having an intake control valve for reducing the cross-sectional area of the intake passage at the time of low speed rotation or low load operation in an intake passage for leading an intake valve opening to an outer wall of a cylinder. In the control device, the control valve includes:
An intake recess extending in the axial direction is formed in a rod having a circular cross-section, and the intake passage is turned around an axial line substantially in parallel with the intake passage on a wall surface on the mating side with the cylinder block of the intake passage. When the control valve is turned to the closed position, the passage cross-sectional area becomes narrower toward the intake valve opening side, and when the control valve is turned to the fully open position, the intake recess is substantially continuous with the wall surface of the intake passage. It is characterized by doing.

[0006]

According to the intake control apparatus of the present invention, when the amount of intake air is small, such as during low-speed rotation, the intake control valve is rotated to the closed position, whereby the cross-sectional area of the intake passage becomes closer to the intake valve opening side. The more narrow it becomes. Therefore, the equivalent pipe length becomes longer, the filling efficiency at the time of low-speed rotation and the like is improved, and the low-speed torque is improved. Even when the amount of intake air is small, the intake air is blown into the combustion chamber with its flow velocity increased, so that lean air-fuel ratio combustion is stabilized, and fuel efficiency at low speed rotation and the like is improved. In addition, when the intake air amount is large, such as during high-speed rotation, the intake control valve rotates to the open position, and the intake concave portion thereof is substantially flush with the wall surface of the intake passage. It is possible to avoid an increase in intake resistance during rotation or the like.

[0007]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 to 8 are views for explaining an intake control device for a four-valve engine according to one embodiment of the present invention.

In the figure, 1 is a water-cooled 4-cycle parallel 4
It is a four-cylinder cylinder engine,
The cylinder block 3 and the cylinder head 4 are stacked on the upper side in a forwardly inclined state and connected with a head bolt.
And a structure in which a head cover 5 is put on the upper mating surface of the head. A piston 7 is slidably inserted into each of the four cylinder bores 3a formed in the cylinder block 3, and each piston 7 is connected to a crankshaft (not shown) by a connecting rod 8.

A lower surface 4a of the cylinder head 4 on the side of the cylinder block 3 has a combustion recess 4b forming a combustion chamber.
Is recessed. An ignition plug 9 is screwed into the center of the combustion recess 4b, and two intake valve openings 4c and two exhaust valve openings 4d are opened around the plug 9. The valve plate 1 of the exhaust valve 10 is provided in each exhaust valve opening 4d.
In the intake valve opening 4c, a valve plate 11a of the intake valve 11 is disposed so as to open and close the openings 4d and 4c, respectively. The valve shafts 10b, 11b of the exhaust and intake valves 10, 11 extend obliquely in the cylinder axis direction so as to form a predetermined angle when viewed in the cam axis direction, and have exhaust and intake lifters 12, 13 at their upper ends. Are attached. Each lifter 1
Exhaust and intake camshafts 1 for driving them are provided on 2 and 13.
4 and 15 are arranged in a direction perpendicular to the cylinder axis and parallel to each other. Although not shown, the above exhaust,
A cam chain connecting the intake camshafts 14, 15 and the crankshaft is arranged in a chain chamber formed at the center of the four cylinder bores 3a.

The two exhaust valve openings 4d are led out to the front wall 4f side of the cylinder head 4 through a bifurcated exhaust passage 16, and the exhaust device 2 is inserted into a wall opening 16a of the exhaust passage 16.
7 are connected to the exhaust manifold 27f. As shown in FIG. 5, the junction 27 of the exhaust manifold 27f
a has an exhaust control valve 2 for controlling the cross-sectional area of the exhaust passage;
A drive pulley 27b is fixed to one end of the exhaust control valve 27c.

The two intake valve openings 4c are led to the rear wall 4g of the cylinder head 4 through forked intake passages 17,17. Each intake passage 17 extends obliquely slightly inward with respect to a line perpendicular to the camshaft when viewed in the cylinder axis direction, and when viewed in the camshaft direction, the intake valve opening 4.
After being bent in an arc shape from c to the cylinder rear wall 4g side, it extends substantially linearly. A carburetor 19 is connected to a wall opening 17 a of the intake passage 17 via an intake manifold 18. This intake manifold 18 is provided with a holding bracket 1 for holding an intake control valve driving mechanism described later.
The holding bracket 18a is connected and fixed to the wall opening 17a, and the discharge port of the vaporizer 19 is connected and fixed to the cab joint 18b. The carburetor 19 is of an automatic variable venturi type having a butterfly type throttle valve 19a which opens and closes by a throttle operation, and a piston valve 19b which automatically opens and closes by negative pressure of the intake air of the engine. An air cleaner 20 is connected to a suction port 19 c of the vaporizer 19.

A valve hole 17c is formed in a bottom wall portion of each of the intake passages 17 so as to open to the bottom wall surface. When viewed in the cylinder axis direction, the valve holes 17c are slightly inclined inward so that the intake passages 17 are located more inward toward the outside, but at right angles to the straight line connecting the cylinder axes. (See FIG. 2). On the other hand, when viewed in the camshaft direction, it is slightly oblique to the intake passage 17 so that the intake valve opening 4c is located closer to the intake passage inside.

An intake control valve 21 for changing the cross-sectional area of the intake passage 17 is provided in each of the valve holes 17c so as to be rotatable around its axis. This intake control valve 21
Is formed by notching a U-groove-shaped intake concave portion 21a in a round bar over the entire length thereof, and an inclined surface 21c at a tip thereof.
The pinion 21b is formed at the rear end. The intake recess 21a forms a continuous surface with the inner wall surface of the intake passage 17 when the control valve 21 is rotated to the fully open position (see FIGS. 6 and 7). When the control valve 21 is rotated to the fully closed position, the valve hole 17 is rotated as described above.
Since c is oblique to the intake passage 17,
The passage cross-sectional area of the intake passage 17 is gradually reduced toward the downstream side (see FIGS. 1, 3, and 4).

A slide hole 18c is formed in the holding bracket 18a of the intake manifold 18 in a direction perpendicular to each of the control valves 21, and a plug 18d is screwed into a leading end opening of the slide hole 18c. ing. A drive shaft 22 having a rack 22a is slidably inserted into the slide hole 18c, and the pinion 21b of the control valve 21 is engaged with the rack 22a. One end of a drive arm 22b pivotally supported by the holding bracket 18a is connected to an outer end of the drive shaft 22, and a drive cable 25a is connected to the other end of the drive arm 22b.

Drive cable 25a for intake control valve 21
The drive cable 25b connected to the drive pulley 27b of the exhaust control valve 27c is connected to a drive motor 23a, and the drive of the drive motor 23a is controlled by a control unit 23b. 23c is a main switch, and 23d is a battery.

Next, the operation and effect of this embodiment will be described. When the intake air amount is small as in the case of low-speed rotation of the engine or low-load operation, as shown in FIGS.
The intake control valve 21 is turned to the fully closed position. Therefore, the intake passage 17 is narrowed from the bottom wall side, and only the top wall side is opened. In this case, since the intake control valve 21 is inclined inward of the intake passage 17 with respect to the intake passage 17 when viewed in the camshaft direction, the intake control valve 21 is gradually narrowed toward the intake valve opening 4c. Also, when viewed in the cylinder axis direction, the intake passage 17 is oblique to the line connecting the cylinder axes, while the intake control valve 21 is at a right angle. Is gradually squeezed. As a result, the equivalent pipe length of the intake passage 17 is increased, the volume efficiency at the time of low-speed rotation is improved (see FIG. 8), and the low-speed torque is accordingly increased. Further, the flow rate of the intake air is gradually increased by the intake control valve 21 and is blown into the combustion chamber at a high speed and direction, thereby generating a vertical swirl as shown by an arrow in FIG.
As a result, even if the air-fuel ratio is made lean, combustion can be stabilized, and fuel efficiency can be improved. In addition, each intake control valve 21
Are arranged in parallel with each other, so that even in a multi-cylinder engine, it is possible to cope with the structure without significantly complicating the structure. Furthermore, at low speed rotation, etc., the exhaust manifold 27
The exhaust control valve 27c disposed in the collecting portion 27a of the valve f rotates in conjunction with the intake control valve 21 to reduce the exhaust passage area. As a result, the exhaust efficiency is improved, and from this point as well, the charging efficiency can be improved and the low-speed torque can be improved.

When the intake air amount is large, such as when the engine is rotating at a high speed or during a high-load operation, the intake control valve 2 is used.
1 is rotated to the fully open position, whereby the intake recess 21a forms a continuous surface with the wall surface of the intake passage 17 (see FIGS. 6 and 7), and the intake control valve 21 does not become an intake resistance.

FIGS. 9 and 10 show modifications of the intake concave portion of the intake control valve. In the drawings, the same reference numerals as those in FIGS. 3 and 4 denote the same or corresponding parts. In this modification, an inclined surface 21d is formed in the intake control valve 21 on the back side of the intake concave portion 21a. The inclined surface 21d is formed such that the boundary portion between the adjacent intake passages 17, 17, that is, the center portion of the cylinder, becomes lower when viewed in the intake passage direction. As a result, when the intake control valve 21 is rotated to the fully closed position, a portion corresponding to the center of the cylinder of the intake passage opens larger,
Therefore, more intake air flows into the center of the combustion chamber.

FIGS. 11 and 12 show an embodiment in which the present invention is applied to a fuel injection engine. In the drawings, the same reference numerals as those in FIG. 1 denote the same or corresponding parts. In the present embodiment, a fuel injection valve 26 is mounted on a top wall portion of the intake passage 17, and the injection nozzle of the fuel injection valve 26 is connected to the intake control valve 2 via an injection hole 26a.
1, that is, a portion extending from the most narrowed portion of the intake passage area to the back surface of the valve plate 11 a of the intake valve 11. A throttle body 24 is connected to a rear wall opening 17a of the intake passage 17 via an intake manifold 18, and a throttle valve 24a is rotatably disposed in the body 24. Although not shown, the drive of the throttle valve 24a is controlled in conjunction with the drive shaft 22. In the present embodiment, the fuel injected from the fuel injection valve 26 also hits the intake control valve 21, so that the control valve 21 can be cooled. In addition, since fuel is injected into the narrowest part of the intake passage area, fuel transfer delay is small,
And atomization becomes good.

In the present invention, since the intake control valve for controlling the area of the intake passage is provided, the lean air-fuel ratio combustion can be stabilized, the CO can be reduced and the fuel efficiency can be improved, but the exhaust gas temperature decreases. In addition, there is a concern that the treatment of HC by the catalyst becomes difficult. In particular, in the case of a high-speed type engine, since the catalyst is arranged as far away from the engine as possible to reduce the resistance of the exhaust gas, the exhaust gas temperature is further lowered, and the above problem is considered to be more remarkable. On the other hand, if the catalyst is brought closer to the engine simply by shortening the exhaust pipe, there is a concern that the exhaust efficiency will deteriorate at low speed rotation and engine performance will decrease.

FIGS. 13 and 14 show a catalyst arrangement structure in which the catalyst can be arranged as close as possible to the engine in order to solve the problem caused by the decrease in the exhaust gas temperature. In the figure, reference numeral 27 denotes an exhaust device, which is an exhaust manifold connected to the exhaust port of each cylinder (see reference numeral 27f in FIG. 1).
Is connected to one collecting portion 2 by each exhaust pipe 27g connected thereto.
7a, and the catalyst chamber 27e is
And a silencer 2 is provided in the chamber 27e.
7d are connected. An exhaust control valve 27c for controlling the area of the opening 27h in the collecting section of each exhaust pipe 27g, that is, an exhaust passage area, is provided in the collecting section 27a, and the catalyst chamber 27e connected to the collecting section 27a. Inside, a catalyst unit 28 is provided. The exhaust control valve 27c is controlled in conjunction with the intake control valve via a wire cable (not shown) wound around a pulley 27b.

In this arrangement, the exhaust control valve 27c for reducing the exhaust passage area when the engine is running at a low speed is provided, so that the operation at a low speed can be stabilized even if the length of the exhaust pipe is shortened.
As described above, when the length of the exhaust pipe is reduced, the negative pressure wave of the exhaust acts on the exhaust valve opening during high-speed rotation to improve the exhaust efficiency. Efficiency decreases. However, in this embodiment, the positive pressure wave of the exhaust gas can be canceled by the exhaust control valve 27c, and the above-described stabilization can be achieved. Therefore, as compared with the case where the exhaust control valve is not provided, the catalyst 28 can be brought closer to the exhaust port of the engine, and the decrease in the exhaust gas temperature can be suppressed accordingly, which is advantageous in the treatment of HC. In addition, the heat capacity of the exhaust pipe is reduced by the shortened length of the exhaust pipe, and the time until activation is started when the engine is started is shortened.

As described above, this arrangement in which the exhaust control valve 27c is provided and the catalyst 28 is disposed immediately downstream of the exhaust control valve 27c stabilizes the lean combustion by controlling the intake passage area as in the above embodiment. It is effective for engines that can be used.

FIGS. 15 to 18 show that the length of the exhaust pipe can be increased when the engine is running at low and medium speeds and shortened when the engine is running at high speed.
This is another catalyst arrangement structure capable of suppressing a decrease in exhaust gas temperature. In the drawings, the same reference numerals as those in FIGS. 13 and 14 indicate the same or corresponding parts. In this arrangement, each exhaust pipe is divided into a front exhaust pipe 27g and a rear exhaust pipe 27i, and a valve chamber 27j and a catalyst chamber 27e are interposed therebetween. A catalyst 28 is provided in the catalyst chamber 27e. The catalyst 28 is of a monolith type in which a large number of passages 28a in a lattice shape have an upstream side passing through a downstream side. The rear exhaust pipe 27i is gathered on the left side in the figure, and the valve chamber 27j has a shape bulging upward.

A gate valve 30 is provided in the valve chamber 27j.
Are located at the standby position located in the bulging portion and each front exhaust pipe 2.
It is disposed so as to be vertically rotatable with respect to a partition position located on an extension of 7 g. This gate valve 30 is provided with a valve shaft 30.
a, five valve plates 30b are fixed to each of the valve plates 30b.
0b is covered with a cover plate 30d. The gate valve 30 is opened and closed by a control motor (not shown) via a drive pulley 30c mounted on an outwardly projecting end of the valve shaft 30a and a drive cable 30e wound therearound.

At the time of low-speed rotation, the gate valve 30 rotates to the partition position, whereby the front exhaust pipe 27g is connected to the passage formed by the partition plate 30b, the cover plate 30d and the bottom surface of the valve chamber 27j, and the catalyst. 28 and a rear exhaust pipe 27i. Further, at the time of high-speed rotation, the gate valve 30 rotates to the standby position, whereby the front exhaust pipes 27g are gathered by the valve chamber 27j, and thus the length of the exhaust pipe is shorter than at the time of low-speed rotation.

As described above, in this arrangement, each exhaust pipe is separated before and after, and the catalyst 28 is disposed between them, so that the catalyst 28 is closer to the exhaust port, and the temperature of the exhaust gas can be reduced accordingly. Also, at low speed rotation, the gate valve 30,
The exhaust pipe length can be increased by connecting the front and rear exhaust pipes with the catalyst 28, and the exhaust pipe length can be shortened by gathering the front exhaust pipe 27g in the valve chamber 27j during high-speed rotation. As a result, the output can be improved both at low speed rotation and at high speed rotation.

As described above, according to the intake control system for an engine according to the present invention, the intake control valve is formed in a rod shape and is disposed on the bottom wall portion of the intake passage in the direction of the passage. Can reduce the intake passage cross-sectional area gradually toward the downstream side, so that the equivalent pipe length at the time of low-speed rotation, etc. becomes longer, which has the effect of improving the charging efficiency and improving the low-speed torque. The intake air can be blown into the combustion chamber at an increased flow velocity, so that lean air-fuel ratio combustion can be stabilized and low-speed fuel efficiency can be improved. Furthermore, at the time of high-speed rotation or the like, the intake recess of the intake control valve forms a substantially continuous surface with the wall surface of the intake passage, so that the intake resistance does not increase.

[Brief description of the drawings]

FIG. 1 is a sectional side view of an intake control device for an engine according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along line II-II of FIG.

FIG. 3 is a sectional view taken along line III-III of FIG. 1;

FIG. 4 is a sectional view taken along line IV-IV of FIG. 1;

FIG. 5 is a sectional view taken along line VV of FIG. 1;

FIG. 6 is a cross-sectional view showing a state at the time of high-speed rotation of the intake control valve of the embodiment.

FIG. 7 is a cross-sectional view showing a state at the time of high-speed rotation of the intake control valve of the embodiment.

FIG. 8 is an engine speed-volume efficiency characteristic diagram for explaining the operation and effect of the embodiment.

FIG. 9 is a sectional view showing a modified example of the intake control valve portion of the embodiment.

FIG. 10 is a sectional view showing a modified example of the intake control valve portion of the embodiment.

FIG. 11 is a sectional side view showing an embodiment when the present invention is applied to a combustion injection type engine.

12 is a sectional view taken along line XII-XII of FIG.

FIG. 13 is a sectional plan view showing a catalyst arrangement structure suitable for an engine including the intake control device of the embodiment.

FIG. 14 is a sectional side view of the catalyst arrangement structure.

FIG. 15 is a cross-sectional side view showing another catalyst arrangement structure suitable for an engine including the intake control device of the embodiment.

FIG. 16 is a cross-sectional plan view of another catalyst arrangement structure.

FIG. 17 is a sectional view taken along line XVII-XVII in FIG. 16;

18 is a sectional view taken along line XVIII-XVIII in FIG.

[Explanation of symbols]

 Reference Signs List 1 engine 4a mating surface 4c intake valve opening 4g cylinder outer wall 17 intake passage 21 intake control valve 21a intake recess

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) F02B 27/02 F02B 29/02 F02B 31/00

Claims (1)

(57) [Claims] 1. An intake control system for an engine having an intake control valve for reducing a passage cross-sectional area during a low-speed rotation or a low-load operation in an intake passage that leads an intake valve opening to an outer wall of a cylinder. , While forming a suction recess extending in the axial direction in a rod having a circular cross section,
The intake passage is disposed on a wall surface on the side of the mating surface with the cylinder block so as to be rotatable substantially in parallel with the intake passage and around an axis. An intake control device for an engine, wherein the intake concave portion forms a substantially continuous surface with a wall surface of an intake passage when the valve is narrowed toward a valve opening side and rotated to a fully open position.