JPH06193452A - Intake air control device for engine - Google Patents

Abstract

PURPOSE:To provide an engine intake air control divice which can prevent turbulance of intake air flow and generate tumble with certainty. CONSTITUTION:An intake air control device comprises such an intake air control valve 21 as allowing intake air to flow while deviating it to the side of the ceiling wall 17f of an intake passage 17 by throttling the bottom wall 17d of the intake air passage 17, and such a streamlining member 20 as streamlining the intake air to the ceiling wall side flow and the bottom wall side flow at a downstream side part from the intake control valve 21 of the intake passage 17. A control means for setting minimum opening of the intake air control valve 21 in such a way that the higher an engine speed is, the larger it is, under a small throttle valve opening condition. An intake air amount flowing into the bottom wall side portion on the downstream side of the intake air control valve is increased follwing the increase in an intake flow rate, so that turbulance of the intake air caused by a negative pressure is suppressed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention prevents turbulence of the intake air flow and reliably generates tumble when the intake air passage area is variably controlled by an intake air control valve arranged in the intake air passage. The present invention relates to an intake control device for an engine.

[0002]

2. Description of the Related Art In order to improve the fuel efficiency of an engine,
A lean air-fuel ratio engine with a high A / F (air-fuel ratio) has been put into practical use. In order to further improve the fuel consumption rate in such an engine, it is possible to stabilize the lean combustion by generating, for example, tumble (longitudinal vortex) in the combustion chamber by increasing the flow velocity of the intake air even in an operating region where the intake air amount is small. It is known to be effective. As an intake control device capable of generating such a tumble, the applicant of the present application first arranged the intake control valve rotatably in the bottom wall of the intake passage, and intake air at a portion downstream of the intake control valve. A rectifying member is arranged to rectify the flow of the intake air to the top wall side and the bottom wall side, and when the intake air amount is low, the intake air is diverted to the top wall side by narrowing down the bottom wall side part of the intake passage. An intake control device has been proposed in which intake air is allowed to flow in vertically from the center of the combustion chamber (for example, Japanese Patent Application No. 3-11.
1182).

[0003]

By the way, in the intake control device according to the above-mentioned proposal, when the intake air amount is low as described above, the intake control valve is closed to narrow the intake passage area and increase the intake flow velocity, thereby reducing the tumble. I am trying to raise it. By the way, even when the throttle opening is low, the intake interval becomes shorter as the engine speed increases, and the intake air amount due to the intake inertia increases accordingly. Therefore, depending on the control of the opening degree of the intake control valve, the intake control valve may become an intake resistance and the intake intake amount may decrease.

Further, in the above-mentioned proposed device, tumble is generated by narrowing the intake control valve to increase the flow velocity and rectifying the intake flow by the rectifying member. However, when the intake passage is narrowed by the intake control valve, the space surrounded by the rectification member and the bottom wall on the downstream side of the intake control valve becomes negative pressure, and the intake flow is introduced from the downstream side of the rectification member to the space. It was found that the tumbles were apt to be caught in the and the tumbles could not be obtained as expected.

The present invention has been made in view of the above circumstances, and provides an intake control device for an engine capable of reliably generating tumble by preventing an increase in intake resistance when the intake passage is narrowed and a disturbance in the intake flow. The purpose is to do.

[0006]

According to a first aspect of the present invention, an intake control valve that allows intake air to flow toward a top wall of an intake passage by narrowing the bottom wall side portion in the bottom wall of the intake passage. The intake control of the engine is characterized in that the opening control means is provided for rotatably arranging and controlling the minimum opening of the intake control valve to increase as the engine speed increases at low throttle valve opening. It is a device.

According to a second aspect of the present invention, a rectifying member for rectifying the intake air into a flow on the top wall side and a flow on the bottom wall side is provided in a portion of the intake passage downstream of the intake control valve, and a low throttle is provided. At the time of opening, the minimum opening of the intake control valve is controlled to be large so that the clearance between the rectifying member and the intake control valve becomes larger as the engine speed increases.

[0008]

According to the intake control device of the present invention, the intake control valve rotates to the closing side when the throttle valve opening is low. In this case, the higher the engine speed, the more the intake control valve operates. The minimum opening is largely controlled. Therefore, it is possible to avoid the intake control valve from increasing the intake resistance when the intake inertia increases due to the increase in the engine speed and the intake amount increases, and as a result, a sufficient intake amount is obtained.

According to the second aspect of the present invention, the lower the engine speed and the intake air amount, the smaller the gap between the intake control valve and the rectifying member, and the higher the engine speed and the intake air amount. Opening / closing is controlled so that the above-mentioned gap becomes large. As a result, when the intake air amount is low, almost all of the intake air flows through the portion of the intake passage that is closer to the ceiling wall than the rectifying member, so the intake flow velocity is not reduced so much, and as the intake air amount increases, The negative pressure generated in the bottom wall side portion downstream of the intake control valve by the inflow of the intake air can be suppressed, and the turbulence of the intake air can be prevented. As a result, tumble can be reliably generated while preventing turbulence of intake air even if the intake air amount changes, and fuel consumption can be improved.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 4 are diagrams for explaining an engine intake control device according to an embodiment of the present invention, FIGS. 1 to 3 are diagrams for explaining the structure of the present embodiment device, and FIG. 4 is an engine. It is a three-dimensional map figure which shows the relationship of rotation speed-slottle valve opening-intake control valve opening.

In FIG. 1, reference numeral 1 denotes a water-cooled four-cycle four-valve engine, in which a cylinder block 3 and a cylinder head 4 are stacked on a crankcase 2 and fastened with head bolts, and the cylinder head 4 has a head cover side. The structure is such that the head cover 5 is attached to the mating surface 4i.
Cylinder bore 3a formed in the cylinder block 3
A piston 7 is slidably inserted therein, and the piston 7 is connected to a crankshaft (not shown) by a connecting rod 8.

On the cylinder block side mating surface 4a of the cylinder head 4, a combustion concave portion 4b forming a combustion chamber is provided. The combustion recess 4b has two intake valve openings 4c and two exhaust valve openings 4d. At each exhaust valve opening 4d, the valve head 10a of the exhaust valve 10 is
The valve head 11a of the intake valve 11 is provided in each intake valve opening 4c.
Are arranged so that they can be opened and closed, respectively. The valve stems 10b and 11b of the exhaust and intake valves 10 and 11 extend obliquely upward so as to form a predetermined included angle when viewed in the cam axis direction, and exhaust and intake lifters 12 and 13 are attached to the upper ends thereof, respectively. Has been done. Further, on each of the lifters 12 and 13,
Exhaust and intake cam shafts 14 and 15 that press and drive the cylinders are arranged in a direction perpendicular to the cylinder axis and parallel to each other. In addition, 12a and 13a are valve springs for urging each valve in the closing direction, and 29 is an ignition plug.

The two exhaust valve openings 4d are led out to the front wall 4f side of the cylinder head 4 by a bifurcated exhaust passage 16, and an exhaust pipe (not shown) is provided in a wall opening 16a of the exhaust passage 16. It is connected. In addition, each intake valve opening 4
c and 4c 'are led out to the rear wall 4g side of the cylinder head 4 by intake passages 17 and 17', respectively. The intake passages 17 and 17 'are viewed in the cylinder axis direction (see FIG. 3).
They are parallel to each other, and when viewed in the cam axis direction (see FIG. 1), they are bent in an arc shape from the intake valve opening 4c to the cylinder rear wall 4g side and then extend in a substantially straight line shape. A common cab joint 18 is connected to the wall surface openings 17a of the intake passages 17 and 17 ', and joins into one passage in the joint 18. One carburetor 19 is connected to the cab joint 18. The carburetor 19 is of an automatic variable venturi type having a butterfly type throttle valve 19a which is opened and closed by a throttle operation and a piston valve 19b which is automatically opened and closed by an intake negative pressure of the engine.

A valve hole 17c is formed in the bent portion 17b of the intake passage 17 near the opening of the intake valve in the cam shaft direction. The axis of the valve hole 17c is the intake passage 17
Is located in the vicinity of the surface of the bottom wall 17d, the inner portion of the intake passage 17 is formed in a substantially semicircular shape, and communicates two adjacent intake passages for cylinders.

In the valve hole 17c, each intake passage 17,
Intake control valve 21 for changing the passage cross-sectional area of 17 '
Is rotatably inserted and arranged. This intake control valve 21
Is formed by notching a part of the round bar so as to form a continuous surface with the lower inner surface of the intake passage 17, thereby forming a valve portion 21a for opening and closing the intake passages 17 and 17 '. Is sunk into the valve hole 17c and is flush with the inner surface of the intake passage, and the valve portion 21a stands substantially vertically from the surface of the bottom wall 17d so that the intake passage 17 is 50 to 70%, preferably 67%. It can be rotated between the fully closed position and the closed position. In this case, the valve portion 21a is rotated so that the outer peripheral surface thereof is located on the upstream side.

A switching valve 26 is arranged in the cab joint 18. The switching valve 26 includes a valve shaft 26a arranged to penetrate the joint 18 in parallel with the intake control valve 21, and a valve plate fixed to the valve shaft 26a for opening and closing the one intake passage 17 '. 26b.

A rectifying member 20 is arranged downstream of the intake control valve 21 on the side of the intake passage 17 where the valve plate 26b of the switching valve 26 is not provided. This straightening member 20
Is configured by connecting and fixing an annular holding ring 20b to the downstream end of a tongue-shaped current plate 20a, and projecting a convex locking portion 20c on the outer peripheral surface of the holding ring 20b. The locking portion 20c is fitted in a concave portion of the inner peripheral surface of the valve seat 11d press-fitted into the intake valve opening 4c.

The current plate 20a extends substantially along the center line of the intake passage 17 and has the same width as the intake passage 17. The downstream end 20e of the straightening vane 20a is located closer to the combustion chamber than the press-fitting end of the valve seat 11d, and the downstream end 20e is the valve stem 11.
It is located closer to the spark plug 29 than the center of the cylinder. Further, an insertion hole 20d through which the valve stem 11b of the intake valve 11 is inserted is formed in the upper part of the straightening plate 20a.

The upstream end 20f of the straightening plate 20a abuts on the upper end of the valve portion 21a of the intake control valve 21 in the fully closed position, and forms a continuous surface with the upper end portion of the valve portion 21a. On the downstream side of the intake control valve 21, the flow is biased toward the top wall side portion C side and is rectified by the rectifying plate 20a.

The outward protruding portion of the intake control valve 21 is connected to the control motor 30 via a pulley and a cable.
The outward protruding portion of the switching valve 26 is connected to the switching motor 31 via a pulley and a cable. The rotations of the control motor 30 and the switching motor 31 are controlled by the ECU 23.

The ECU 23 receives the opening signal a of the throttle valve 19a from the throttle opening sensor 24 and the engine speed signal b from the rotation sensor 25, and controls the intake control valve 21 according to the map shown in FIG. A control signal B for outputting the control signal A to the control motor 30 and for closing the switching valve 26 in an operating range where the intake air amount is below a predetermined amount and opening it in an operating range where the intake air amount exceeds the predetermined amount. Is output to the switching motor 31.

The ECU 23 constitutes an opening control means for the intake control valve 21. The opening control means is set to increase the minimum opening of the intake control valve 21 as the engine speed signal b from the rotation sensor 25 increases. As a result, when the throttle valve opening is low, the opening A of the intake control valve 21 is increased so that the gap A between the upstream end 20f of the straightening plate 20a and the valve 21a of the intake control valve 21 becomes larger as the engine speed increases. Controlled.

Next, the function and effect of the apparatus of this embodiment will be described. In this embodiment, the control signal A from the ECU 23
The control motor 30 controls the opening / closing of the intake control valve 21, and the control signal B from the ECU 23 controls the switching motor 31 to open / close the switching valve 26.

The switching valve 26 is controlled to be opened and closed by the ECU 23, and one of the intake passages 17 'is operated in a low speed / low load operation range in which the required intake air amount is small and in a medium speed / medium load operation region in which the required intake air amount is medium. Then, close it completely. As a result, intake air flows only in the other intake passage 17. Further, in the high speed / high load operation range where the required intake air amount is large, the switching valve 26 fully opens the intake passage 17 '. As a result, intake air is in the intake passage 1
It flows through both 7, 17 '.

Further, the ECU 23 reads the engine speed signal b and the throttle opening signal a, calculates the intake control valve opening from the built-in three-dimensional map of FIG. 4, and controls the control motor 30 according to the opening. To drive. That is, when the engine is idling, the intake control valve 21 is rotated to the fully closed position as shown in FIG. 2 regardless of the throttle valve opening, and the valve portion 21a of the intake control valve 21 is Current plate 20
It is in contact with the upstream end 20f of a. As a result, the intake air is concentrated in the intake passage 17 on the other side and is biased toward the top wall side portion C of the passage 17 to reliably generate tumble even when the intake amount is the smallest. In this case, as shown in FIG. 2, since the intake flow velocity is small, the eddy turbulent flow E due to the negative pressure in the bottom wall side portion D hardly occurs.

When the throttle valve opening is a1 to a4 (for example, 10 degrees or less), the engine speed is b1.
When rising to ~ b4, the intake control valve 21 gradually opens to c1 to c4, whereby the gap A between the valve portion 21a of the intake control valve 21 and the upstream end 20f of the flow straightening plate 20a gradually increases. Therefore, most of the intake air flows in a biased manner to the top wall side portion C, and a part of the intake air flows into the bottom wall side portion D from the gap. Then, at each of the engine speeds, when the throttle valve opening further increases, the intake control valve 21 rotates to the fully open position.

Since the gap A is narrow when the engine speed is low, almost all of the intake air is in the top wall side portion C.
Flow, the flow velocity becomes faster, and tumble is likely to occur. Further, in this case, since the flow rate is small, the above-mentioned negative pressure is unlikely to be generated, and therefore the flow is not disturbed. on the other hand,
As the engine speed increases, the minimum opening of the intake control valve 21 increases and the gap A widens, and the amount of intake air flowing to the bottom wall side portion D increases accordingly, which suppresses the generation of negative pressure and reduces the tumble. It certainly occurs. Further, in this case, the intake resistance by the intake control valve 21 can be reduced as much as the minimum opening degree of the intake control valve 21 is large.

Here, as indicated by the alternate long and short dash line in FIG. 4, the intake control valve 21 has a linear or arcuate control curve F that gradually increases from the minimum opening to full opening.
You may control along 1 and F2. In addition, the intake control valve 2
The minimum opening degree of 1 may be controlled along the curve F3 so as to gradually and continuously increase according to the engine speed. Furthermore, in the normal region where the engine power is not so required, the minimum opening degree of the intake control valve 21 may be lowered from c2 to c1 as indicated by the straight line F4. In this case, combustibility can be improved and intake noise can be reduced.

As described above, according to this embodiment, the minimum opening degree of the intake control valve 21 is fully closed at the time of idle rotation, and is set larger as the engine speed is higher. The gap A between the straightening vane and the intake control valve becomes wider, and a part of the intake air flows into the bottom wall side portion D from here, thereby reliably generating the tumble while preventing the turbulent flow E of the intake air. Therefore, the combustibility can be further improved, and the fuel consumption can be improved.

In the above embodiment, the valve portion 21a of the intake control valve 21 when the valve is fully closed is replaced by the upstream end portion 2 of the straightening plate 20a.
Although the case of abutting against 0f has been described as an example, in the present invention, as shown in FIG. 5, a gap t may be provided in advance between the valve portion 21a and the current plate 20a when fully closed. Also in this case, by setting the minimum opening degree of the intake control valve 21 in accordance with the engine speed, substantially the same effect as the above embodiment can be obtained.

The present invention can also be applied to the case where no rectifying member is provided. In this case, it is possible to avoid an increase in intake resistance at low throttle opening and high engine speed.

[0032]

As described above, according to the intake control system for an engine of the present invention, the minimum opening of the intake control valve is increased as the engine speed becomes higher at a low throttle valve opening. By doing so, the amount of intake air that flows into the bottom wall side through the gap between the intake control valve and the rectifying member is controlled, so it is possible to avoid an increase in intake resistance, prevent turbulence of intake air, and ensure tumble. There is an effect that can be generated.

[Brief description of drawings]

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

FIG. 2 is an enlarged view of an intake control valve and a rectifying member portion of the above embodiment.

FIG. 3 is a cross-sectional plan view of the intake passage of the above embodiment.

FIG. 4 is a map diagram showing a relationship of engine speed-throttle valve opening-intake control valve opening in the above embodiment.

FIG. 5 is an enlarged view of an intake control valve and a rectifying member portion of a modified example of the above embodiment.

[Explanation of symbols]

 1 engine 17 intake passage 17d bottom wall 17f ceiling wall 20 rectifying member 21 intake control valve ECU control valve opening degree control means

Claims (2)

[Claims] 1. A rotatably disposed on the bottom wall of the intake passage,
An intake control valve that narrows the bottom wall side portion of the intake passage to flow the intake air toward the top wall side of the intake passage, and the minimum of the intake control valve as the engine speed increases at low throttle valve opening. An intake control device for an engine, comprising an opening control means for largely controlling the opening. 2. A rectifying member for rectifying the intake air into a flow on the top wall side and a flow on the bottom wall side is arranged downstream of the intake control valve in the intake passage, and the opening control means comprises: An intake control of an engine, wherein the minimum opening of the intake control valve is controlled to be large so that the clearance between the rectifying member and the intake control valve increases as the engine speed increases at a low throttle valve opening. apparatus.