JP3318357B2 - 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 system for an engine in which the area of an intake passage is variably controlled, and more particularly, to a reduction in intake air amount due to intake resistance when the intake passage area is reduced. Regarding what you did.

[0002]

2. Description of the Related Art In order to improve the fuel efficiency of an engine, it is necessary to stabilize combustion by generating, for example, a tumble (longitudinal vortex) in a combustion chamber by increasing the flow rate of intake air even in an operation region where the amount of intake air is small. It is known to be effective.
As an intake control device that can generate such a tumble,
The present applicant disposes an intake control valve rotatably in the bottom wall of the intake passage and narrows the bottom wall side portion of the intake passage when the amount of intake air is low to bias the intake air toward the top wall. sink,
Thus, an intake control device has been proposed in which intake air is caused to flow vertically from the center of the combustion chamber (for example, Japanese Patent Application No. 3-111182).

[0003]

However, the intake control device according to the above-mentioned proposal reduces the intake passage area by closing the intake control valve when the amount of intake air is low, that is, in the operation region where the throttle valve opening is small as described above. The squeezing is performed to generate a tumble, thereby stabilizing the combustion. However, this intake control valve has an intake resistance depending on the setting of its operation region, and therefore, there is a concern that the intake air amount is reduced as compared with a case where the intake control valve is not provided at the same throttle valve opening, and the engine output is reduced. .

In order to avoid this problem, in the intake control device according to the above proposal, the intake control valve is fully closed only in a narrow operating range where the throttle valve opening is, for example, about 1/10 or less. The area was small.
Therefore, it is required to expand the operating region of the intake control valve (the operating region in which the intake control valve is fully closed) to expand the region where the fuel efficiency improvement effect is obtained.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has an engine intake control device capable of expanding an operation range in which the intake control valve can be fully closed to operate, thereby expanding an operation range in which an effect of improving fuel efficiency can be obtained. It is intended to provide.

[0006]

According to a first aspect of the present invention, there is provided a supercharging means for pressurizing and supplying intake air, and a supercharging means disposed downstream of the supercharging means for biasing the intake air toward the top wall of the intake passage. An intake control valve for the engine, the intake control valve comprising: a valve portion formed by cutting a part of a round bar so as to form a continuous surface with an inner surface of a bottom wall of the intake passage. The valve portion is inserted and disposed in a valve hole formed in the bottom wall of the intake passage in the direction of the cam shaft, and the valve portion is immersed in the valve hole to be flush with the intake passage inner surface. The intake passage is rotatable between a fully closed position in which the intake passage rises from the valve hole and narrows the intake passage, and a portion of the intake passage downstream of the intake control valve is defined as a top wall passage and a bottom wall passage. The intake control valve is set to the fully closed position when the required amount of air is small and the amount of intake air is small. A switching control for rotating the supercharging means to a low-speed supercharging state when the engine is running at a low speed and a high-speed supercharging state when the engine is running at a high speed, by rotating the turbocharger to the fully open position when the required amount of air is high and the intake air amount is large. Means for controlling the intake of an engine.

According to a second aspect of the present invention, in the first aspect, the supercharging means extends the intake passage in an axial direction so that an inertia supercharging effect can be obtained when the engine rotates at a high speed. A low-speed passage connected to the high-speed passage so as to be located on a bottom wall side of the supercharging passage that is narrowed when the intake control valve is closed, and having an inertial supercharging effect when the engine is running at a low speed; And a switching source for switching between the high-speed passage and the high-speed passage, and the switching control means includes a low-speed passage for the supercharging means at the time of low-speed rotation, and a high-speed passage at the time of high-speed rotation. It is characterized in that it is configured to be selected.

The supercharging means in the present invention may employ a supercharger in addition to the above-described structure for switching the length of the intake passage.

[0009]

According to the intake control device for an engine of the present invention, when the intake air amount is low, the switching control means turns the intake control valve to the closing side to narrow the intake passage area, so that the intake air amount is small. Nevertheless, the intake flow velocity is increased, enabling the generation of tumble, stabilizing combustion, and thereby improving the fuel efficiency.

At the time of low speed rotation, the switching control means sets the supercharging means in the low speed supercharging state, so that an increase in the intake resistance due to the narrowing of the intake passage area can be compensated for by an increase in the intake air amount due to the supercharging. Therefore, the operating range in which the intake passage area can be narrowed by the intake control valve is expanded from, for example, about 1/10 to about 1/6 in throttle valve opening. As a result, the range in which the fuel efficiency improvement effect can be obtained is expanded.

When the amount of intake air is high, the switching control means rotates the intake control valve to the open side. Therefore, an increase in intake resistance caused by the intake control valve can be avoided, and a sufficient intake amount can be secured.

[0012]

Embodiments of the present invention will be described below with reference to the accompanying drawings. 1 and 2 are views for explaining an intake control system for an engine according to an embodiment of the present invention. FIG. 1 is a schematic configuration diagram of the embodiment, and FIG. 2 explains the effects of the present embodiment. FIG. 7 is a characteristic diagram showing a relationship between engine speed, torque, and throttle valve opening for the purpose.

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 and fastened with head bolts. It has a structure in which the head cover 5 is mounted on the surface 4i. A piston 7 slidably inserted into the cylinder bore 3a of the cylinder block 3 is connected to a crankshaft (not shown) by a connecting rod 8.

A combustion recess 4b constituting a combustion chamber is formed in the cylinder head 4 at the cylinder block side mating surface 4a. The combustion recess 4b has two intake valve openings 4c and two exhaust valve openings 4d. An exhaust valve 10 is arranged at each exhaust valve opening 4d, and an intake valve 11 is arranged at each intake valve opening 4c so that each opening can be opened and closed. Exhaust and intake lifters 12 and 13 are mounted on the upper ends of the exhaust and intake valves 10 and 11, respectively. Are arranged in a direction perpendicular to the cylinder axis and parallel to each other.

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 each of the intake valve openings 4c is connected to the bifurcated intake passage 1.
At 7, it is led to the rear wall 4 g side of the cylinder head 4.
When this intake passage 17 is viewed in the camshaft direction (see FIG. 1),
After bending in an arc shape from the intake valve opening 4c to the cylinder rear wall 4g side, it extends substantially linearly.

A circular valve hole 17c is formed through the bent portion 17b of the intake passage 17 near the opening of the intake valve in the direction of the cam shaft. The axis of the valve hole 17c is
Therefore, the inside of the intake passage 17 of the valve hole 17c has a substantially semicircular shape.

An intake control valve 21 for changing the cross-sectional area of the intake passage 17 is rotatably inserted into the valve hole 17c. The intake control valve 21 is formed of a round bar, and has a valve portion 21a formed by cutting out so as to form a continuous surface with the lower inner surface of each intake passage 17. The intake control valve 21 has a fully open position in which the valve portion 21a enters the valve hole 17c and is flush with the inner surface of the intake passage. Can be turned between a fully closed position where the diameter is reduced to approximately 1/2. In this case, the valve 21a rotates so that the outer peripheral surface of the valve 21a is located on the upstream side.

A partition plate 2 is provided downstream of the intake control valve 21.
0 is provided. This partition plate 20 is connected to the intake passage 1.
7 extends to the vicinity of the intake valve opening 4 c along the approximate center line of the intake valve 7 and has substantially the same width as the intake passage 17. The upstream end of the partition plate 20 is in contact with the upper end of the valve portion 21a of the intake control valve 21 which has been turned to the fully closed position, and forms a substantially continuous surface with the outer peripheral surface thereof. Thus, the partition plate 20 defines the intake passage 17 downstream of the intake control valve into a top wall side passage and a bottom wall side passage.

An end of the intake control valve 21 protrudes outside the intake passage, and a control pulley 22 is fixed to the protruding end. The control pulley 22 is connected to a drive pulley 24 fixed to a control motor 23 by a cable 25.

An intake manifold 26 is connected to a wall opening of the intake passage 17. The intake manifold 26 is formed by integrally forming one surge tank 27 common to all cylinders, and a high-speed passage 28 and a low-speed passage 29 provided in pairs for each cylinder. The surge tank 27 is integrally formed with one outside air introduction port 27 a, which can be opened and closed by a throttle valve 30.

The length of the high-speed passage 28 is the length of the passage L1.
Is set so that the inertia supercharging effect can be obtained in cooperation with the low speed passage 29 when the engine is rotating at high speed. The low-speed passage 29 joins the middle of the high-speed passage 28, and its length is set so that the passage length L2 is long enough to obtain an inertial supercharging effect when the engine is running at a low speed. ing. A switching valve 31 is disposed on the upstream side of the low-speed passage merging portion of the high-speed passage 28.

A drive rod 32a of a diaphragm valve 32 is connected to a drive arm 31a fixed to the outer end of the valve shaft of the switching valve 31. The negative pressure chamber 32 b of the diaphragm valve 32 communicates with the surge tank 27 via a negative pressure introducing passage 33. And this negative pressure introduction passage 3
A solenoid valve 34 is provided in the middle of 3.

Reference numeral 35 denotes a CPU (switch control means) which receives an engine speed signal a and a throttle valve opening signal b and outputs control signals A and B to the control motor 23 and the solenoid valve 34, respectively. I do. The control signal A causes the intake control valve 21 to operate at a predetermined engine speed,
It is set to rotate to the fully closed position when the intake air amount is lower than the throttle valve opening degree, and to rotate to the fully open position when the intake air amount exceeds the predetermined rotation speed and the predetermined opening degree.
The control signal B is set so that the solenoid valve 34 is closed when the intake air amount is low and is opened when the intake air amount is high. It is open at the time of quantity.

Next, the operation and effect of this embodiment will be described. In the present embodiment, the control signal A from the CPU 35 is used.
The control motor 23 controls the opening and closing of the intake control valve 21 according to the control signal B from the CPU 35, and the solenoid valve 34 controls the switching valve 31 through the diaphragm valve 32 according to the control signal B from the CPU 35.
Open / close control.

First, when the intake air amount is low such as at low speed and low load, the control motor 23 rotates the intake control valve 21 to the fully closed position as shown in FIG. Valve portion 21a narrows the bottom wall side of the intake passage 17. Further, the solenoid valve 34 is closed by the control signal B, and the diaphragm valve 32 operates the switching valve 31 as shown in FIG.
Is turned to the closed position indicated by the solid line. As a result, the intake air flows from the surge tank 27 through the low-speed passage 29, and flows in a deviated manner in the top wall side passage by the intake control valve 21 and the partition plate 20, and flows into the combustion chamber with a vertical direction from the central portion thereof. I do. As a result, a tumble is generated, and as a result, combustion is stabilized even at a low intake air amount.

Further, in this case, since the intake passage 17 is narrowed to approximately 1/2 by the intake control valve 21 and the partition plate 20, there is a concern that the intake resistance increases and the intake air amount decreases. However, in the present embodiment, the intake air flows through the low-speed side passage 29 having the passage length L2 at which the inertia supercharging effect can be obtained at the time of low-speed rotation. The increase in the intake air amount due to the inertial supercharging can compensate for the decrease in the intake air amount due to the intake resistance.

At the time of a high intake air amount such as a high speed and a high load, the control motor 23 rotates the intake control valve 21 to the fully open position by the control signal A, and the valve portion 21a of the intake control valve 21 takes the intake air. It is flush with the lower inner surface of the passage 17. Further, the solenoid valve 34 is opened by the control signal B, and the diaphragm valve 32 rotates the switching valve 31 to an open position indicated by a two-dot chain line in FIG. As a result, the intake air flows from the surge tank 27 through both the low-speed passage 29 and the high-speed passage 28, without biasing the entire region of the intake passage 17.
It flows into the combustion chamber. In this case, the intake control valve 21 does not have an intake resistance, and a portion of the intake has a passage length L1 at which the inertia supercharging effect is obtained at a high speed.
A sufficient amount of intake air is obtained from flowing through.

As described above, in the present embodiment, the intake control valve 21 is fully closed at the time of low speed rotation and the low intake air amount,
Since the intake passage is switched to the low-speed passage 29, a decrease in the intake air amount due to an increase in intake resistance can be compensated for by an increase in the intake air amount due to inertial supercharging.

FIG. 2 is a characteristic diagram for explaining the effect of the present embodiment. In FIG. 2, the engine speed N indicates the switching point between the low-speed and high-speed intake passages. If the rotation speed 29 exceeds this rotation speed, the high-speed passage 28 is selected in addition to the low-speed passage 29.

The characteristic curves C1 and C2 shown by solid lines indicate that the intake control valve is fully opened and the throttle valve opening is 1 /
The characteristic curves C1 'and C2' indicated by broken lines are torque curves when the intake control valve 21 is fully closed. As shown in the figure, the intake control valve 21 with the throttle valve opening set to about 1/6
It can be seen that the torque is reduced when is fully closed. In order to avoid this decrease in torque, the proposed device uses the intake control valve 21 only when the throttle valve opening is about 1/10 or less.
Was fully closed.

On the other hand, in the present embodiment, when the engine speed is equal to or lower than N, the intake passage is switched to the low-speed passage 29 side, so that the inertia supercharging effect compensates for a decrease in the intake air amount. As a result, a torque characteristic equivalent to that shown by the characteristic curve C2 is obtained while the intake control valve 21 is fully closed. Therefore, even when the throttle valve opening is 1/6, the intake control valve 21 can be fully closed without causing a decrease in torque, and the operating range in which the fuel efficiency improvement effect is obtained is expanded accordingly.

The characteristic curve C3 'is a torque curve when the intake control valve 21 is fully opened. In this embodiment, when the engine speed is lower than N, the intake passage is switched to the low-speed passage 29 side. The intake air amount increases due to the supercharging effect, and the torque characteristic shown in the characteristic curve C3 is obtained.

FIGS. 3 and 4 show an example in which the above-mentioned tumble is generated and another air flow is caused to flow on both sides of the tumble. In FIG. 3, the same reference numerals as those in FIG. Show.

A carburetor 41 is connected to a cylinder wall opening of the intake passage 17 via a cab joint 40, and an air cleaner 42 is connected to a suction port of the carburetor 41. The carburetor 41 is of an automatic variable venturi type having a throttle valve 41a that is opened and closed by a throttle grip, and a piston valve 41c that automatically changes the area of the venturi passage 41b by negative pressure of the intake air of the engine. Reference numeral 41d denotes a pilot nozzle that measures fuel during idling.

The upstream end of the air introduction passage 43 is open on the opposite side of the venturi passage 41b from the pilot nozzle 41d and upstream of the throttle valve 41a. The introduction passage 43 is connected to the cab joint 4.
At the zero point, the air intake passage 17 branches to the left and right side walls, extends to both side portions of the intake control valve 21, and has a downstream end opened to be able to communicate with the valve portion 21a.

When the intake air amount is low, the throttle valve 41
a, the opening degree of the piston valve 41c is small, and the fuel is mainly supplied from the pilot nozzle 41d. Further, the intake control valve 21 is pivoted to the fully closed position, so that the fuel-air mixture from the pilot nozzle 41d flows toward the top wall side of the intake passage 17 so that the tumble flows in the combustion chamber. appear. At this time, air in which fuel is almost not mixed flows through the air introduction passage 43 from the valve portion 21a of the intake control valve 21 so as to be located on both sides of the tumble.

As described above, the dense A / F is located at the center of the combustion chamber.
, And a flow of almost only air is generated on both sides. As a result, a two-layer flow having a high concentration and a low concentration is formed, and the lean mixture can be stably burned as a whole.

[0038]

As described above, according to the intake control apparatus for an engine according to the present invention, when the intake air amount is low, the intake passage area is reduced and supercharging is performed, so that the intake passage area is reduced. An increase in intake resistance can be compensated for by an increase in intake air volume due to supercharging, so that the operating range in which the intake passage area can be narrowed by the intake control valve can be expanded, and as a result, the range in which the fuel efficiency improvement effect can be obtained can be expanded There is. In addition, since the intake control valve is formed by forming a valve portion in a round bar along the shape of the intake passage,
An increase in intake resistance due to the provision of the intake control valve when the intake air amount is high can be avoided.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an intake control device according to an embodiment of the present invention.

FIG. 2 is an engine speed-torque characteristic diagram for explaining the effect of the embodiment.

FIG. 3 is a sectional side view showing a modification of the above embodiment.

FIG. 4 is a cross-sectional plan view of the modification.

[Explanation of symbols]

 Reference Signs List 1 engine 17 intake passage 21 intake control device 26 intake manifold (supercharging means) 28 high-speed passage 29 low-speed passage 31 switching valve 35 CPU (switching control means)

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Claims (2)

(57) [Claims] 1. A supercharging means an intake air pressure supplied, the
It is located downstream of the supercharging means and directs intake air to the top of the intake passage.
An intake control valve that is biased toward the wall
In the air control device, the intake control valve includes a part of a round bar.
Cut so that it can form a continuous surface with the inner surface of the bottom wall of the intake passage.
It has a notched valve part, and the bottom wall of the intake passage is
The valve portion is inserted and disposed in the valve hole formed through, and the valve portion is
The fully open position that is immersed inside and is flush with the inner surface of the intake passage
The fully closed position where the valve section rises from the valve hole to narrow the intake passage
Between the intake passage and the intake control of the intake passage.
A part downstream from the valve is defined as a top wall side passage and a bottom wall side passage
A partition plate is provided, and the intake control valve is set to a required air amount.
When the intake air volume is small and low, the
When the intake air volume is high,
In addition, the supercharging means should be used when the engine is running at low speed.
High-speed supercharging when the engine is running at high speed.
Intake control device for an engine characterized by comprising a switching control means for switching, respectively Re. 2. The supercharger according to claim 1, wherein
The intake passage is extended in the axial direction, and the engine rotates at high speed.
A high-speed passage that can sometimes provide an inertial supercharging effect,
Located on the bottom wall side of the road that is throttled when the intake control valve is closed
A low-speed passage connected to the high-speed passage so as to obtain an inertial supercharging effect when the engine is running at a low speed.
A passage and changeover valve for switching between high-speed passage, and a driving source of the switching valve, the switching control means, said supercharging means, a low-speed path at the time of low speed rotation, high-speed passage during high-speed rotation An intake control device for an engine, characterized in that it is configured to select the following.