JPS6347904B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention improves the volumetric efficiency over a wide operating range of the engine by changing and adjusting the substantial length of the intake pipe in response to changes in engine speed. The present invention relates to an intake system for an internal combustion engine that has a variable length intake pipe and is capable of improving output.

Generally, during operation of an internal combustion engine, the pulsating effect caused by pressure waves in the intake pipe and the inertial effect of the air column in the intake pipe cause the volumetric efficiency to fluctuate greatly as the engine speed changes. If the length of the tube is set to a certain length, the volumetric efficiency will be maximum at a certain engine speed, but even if the engine speed is lower or higher than that, the volumetric efficiency will be the maximum. There is a tendency for efficiency to decrease and output to decrease. and,
The longer the length of the intake pipe, the maximum volumetric efficiency occurs at a lower engine speed, and the shorter the length of the intake pipe, the maximum volumetric efficiency occurs at a higher engine speed. It is.

Conventionally, the length of the intake pipe is usually set to a certain length in advance, and internal combustion engines equipped with such an intake pipe always maintain high volumetric efficiency over a wide operating range of the engine. It was difficult to achieve this, and there remained room for improvement from the viewpoint of fuel economy, power performance, etc.

Therefore, by changing and adjusting the actual length of the intake pipe according to changes in the engine speed, high volumetric efficiency can be achieved at all times over a wide range of engine operation.
A device that improves fuel economy and power performance has already been proposed (see Utility Model Application Publication No. 144815/1983), but in this conventional device, the upstream part of the intake pipe is connected to the intake pipe. It is composed of telescopic double tubes that can expand and contract along the direction.
In order to change the intake pipe length, it is necessary to drive the movable pipe of the double pipes relatively long in the intake direction, and the intake pipe length cannot be changed quickly. A large drive device with a long length is required, and the maximum overall length of the intake pipe must be set at least twice the length of the movable pipe.
There are problems such as the intake device becoming larger as a whole.

SUMMARY OF THE INVENTION An object of the present invention is to provide a compact intake system for an internal combustion engine that allows the intake pipe length to be quickly changed according to the engine speed without causing the above-mentioned problems. In order to achieve this object, the present invention provides an intake pipe length changing device for changing the substantial length of the intake pipe, and a device for changing the substantial length of the intake pipe according to the rotational speed of the engine. In the intake system for an internal combustion engine, the intake pipe length changing device includes an opening provided in a peripheral wall of the intake pipe and extending in the intake direction of the intake pipe. , is supported by the intake pipe so as to be able to reciprocate in a direction perpendicular to the intake direction, and intersects obliquely with the longitudinal side edge of the opening in order to increase the opening amount of the opening from the upstream side in the intake direction by the forward movement. The present invention is characterized in that it includes a valve body having a sloped side edge that can be tilted, and a drive device that is operated and controlled by the control device to reciprocate the valve body.

Hereinafter, one embodiment of the present invention will be described with reference to the drawings. In FIGS. 1 to 3, a multi-cylinder internal combustion engine E has four cylinders 8 ₁ to 8 ₄ arranged in parallel with each other, and each cylinder 8 _{1 Four} combustion chambers 11 are recessed in the cylinder head H so as to face the pistons 12 which are slidably engaged with the cylinder head H. In addition, the cylinder head H has intake and exhaust ports 9 ₁ to 9 that open to each combustion chamber 11.
9 ₄ , 14 ₁ to 14 ₄ are formed, and intake and exhaust valves 10 and 1 which can open and close these ports, respectively.
3 is provided. Furthermore, one side of the cylinder head H is connected to the downstream ends of four intake pipes 5 ₁ to _{5 4 that} communicate with each of the intake ports _{9 1 to} 9 ₄ . A known fuel injection device 7 and throttle valves 6 ₁ to 6 ₄ are provided, and each of the throttle valves 6 ₁ to 6 ₄ is connected to a common throttle valve shaft 6 .

Openings 5a ₁ to 5a ₄ extending linearly in the intake direction are bored in the upper circumferential wall of each intake pipe 5 ₁ to 5 ₄ , and a wide air passage communicating with each of the openings 5 _{a 1} to 5a ₄ is provided. A casing 30 of the air cleaner 1 having a chamber 4 is mounted integrally thereon. The casing 30 is provided with an air suction port 2 on one side of the upper part, and an air filter 3 is housed inside the casing 30.
Clean air that has passed through the filter 3 is drawn from the air chamber 4 into the intake pipes ₅₁ to ₅₄ through the openings _5a1 to _5a4 .

The intake pipes 5 ₁ to 5 ₄ have a substantial length thereof;
That is, an intake pipe length changing device C for changing the effective pipe length is attached. Next, the structure of this device C will be explained. The casing 30 has each intake pipe 5.
A valve assembly 16 is supported so as to be slidable back and forth in a direction perpendicular to the intake direction of the valves ₁ to 5 ₄ , and the valve assembly 16 adjusts the opening amount of each of the openings 5a ₁ to 5a ₄ individually. It is composed of a plurality of flat plate-shaped valve bodies v ₁ to v ₄ that can be rotated, and a frame body 31 that integrally connects these valve bodies v ₁ to v ₄ to each other. Each of the valve bodies v ₁ to v ₄ is configured to increase the opening amount of the openings 5 _{a 1} to 5 a ₄ from the upstream side in the intake direction by forward movement (movement in the X direction in FIG. ₂ ). The intake pipes _5a4 have inclined side edges _s1 to _s4 that can obliquely intersect with the longitudinal side edges of the intake pipes 5a4, and by increasing the opening amount, the effective pipe length of the intake pipes ₅₁ to ₅₄ can be shortened. . The casing 30 also includes a valve assembly 1.
A drive device 18 is provided for reciprocating the valve 6 in a direction perpendicular to the intake direction (X, Y directions in FIG. Concatenated. Drive device 18
The operation of the internal combustion engine 8 is controlled by a control device 21 that generates a control signal based on a rotational speed signal sent from a rotational speed detector 20 that detects the rotational speed of the internal combustion engine 8.

Next, the operation of the above embodiment will be explained. Valve assembly 1
6 is in the solid line position in Fig. 2, each valve body v ₁ ~
The opening amount of the openings _{5a 1 to} 5a ₄ due to v 4 is the minimum, and in Fig. 1, the air inside the air chamber 4 is
The lengthwise section of the intake pipe 5 ₁ as indicated by B ₁
It flows into _the intake pipe ₅₁ through the openings _5a1 to _5a4 of _A0A1 . At this time, the interval _{1 o} is each valve body v ₁ ~
v ₄ , the actual position of the air introduction opening end of the intake pipe 5 ₁ is point A ₁ , and therefore the actual length of each intake pipe 5 ₁ to 5 ₄ is the maximum l ₁ becomes.

When the valve assembly 16 is moved to the intermediate position shown by the imaginary line xi in FIG. 2, the air in the air chamber 4 in _FIG . Openings 5a ₁ to 5a ₄ in section _{0 i}
and flows into the intake pipe ₅₁ . At this time, _{the section io is} closed by each valve body v ₁ to v ₄ ,
The actual position of the air introduction opening end of the intake pipe ₅₁ is Ai
Therefore, the substantial length of each intake pipe 5 ₁ to 5 ₄ becomes intermediate li.

Further, when the valve assembly 16 is moved to the position indicated by the imaginary line xn in FIG. 2, the air in the air chamber 4 in _FIG. Opening 5a ₁ in section _{0 o}
It flows into the intake pipe ₅₁ via _5a4 . In this case, the actual position of the air introduction opening end of the intake pipe ₅₁ is
This is the point An, and therefore the substantial length of each intake pipe 5 ₁ to 5 ₄ is the minimum ln.

FIG. 4 shows various curves showing changes in the volumetric efficiency ηv with respect to the rotational speed Ne of the internal combustion engine. When the substantial length of the intake pipes 5 ₁ to 5 ₄ is l ₁ ,
Assuming that the volumetric efficiency ηv changes as shown, for example, by the curve _a1 , when the substantial length of the intake pipes ₅₁ to ₅₄ is li, the volumetric efficiency ηv changes as shown by the curve ai, for example.
The maximum value of the volumetric efficiency ηv at this time is determined by the substantial length of the intake pipes 5 ₁ to 5 ₄ .
l Move the engine to a higher rotation speed than when setting ₁ . Furthermore, when the substantial length of the intake pipes 5 ₁ to 5 ₄ is ln, the volumetric efficiency ηv changes, for example, as shown by the curve an, and the maximum value of the volumetric efficiency ηv at this time is
Move to the higher rotation speed side of the engine.

Therefore, as long as the substantial length of the intake pipes 5 ₁ to 5 ₄ is set to a constant length, the volumetric efficiency ηv
The range in which the engine speed is high is narrowed down to an extremely narrow engine speed range, but according to this embodiment, the control device 21 controls the engine speed based on the engine speed signal sent from the engine speed detector 20. The operation of the drive device 18 is controlled so as to always obtain the maximum volumetric efficiency ηv・max in response to variations in the rotation speed of the intake pipes 5 ₁ to 5 ₄ . ₁ to ln, a high volumetric efficiency is obtained over a very wide engine speed range, as shown by curve b in Figure 4. High output can be obtained over the operating range.

The present invention is not limited to the illustrated example and includes many embodiments. For example, the rotation speed detector 20 and the control device 21 are not separate units, and the engine rotation speed is detected by a mechanical governor, and the valve assembly 16 is directly moved in sliding contact with the governor. The air cleaner 1 and the air chamber 4 can also be separated remotely.

As described above, according to the present invention, there is provided an intake pipe length changing device for changing the substantial length of the intake pipe, and an intake pipe length changing device for changing the substantial length of the intake pipe, and the intake pipe length changing device for changing the substantial length of the intake pipe. In the intake system for an internal combustion engine, the intake pipe length changing device includes an opening provided in a peripheral wall of the intake pipe and extending in the intake direction of the intake pipe; It is supported by the intake pipe so as to be able to reciprocate in a direction perpendicular to the intake direction, and can obliquely intersect with the longitudinal side edge of the opening in order to increase the opening amount of the opening from the upstream side in the intake direction by its reciprocating movement. Since the valve body includes a valve body having an inclined side edge and a drive device that is operated and controlled by the control device to reciprocate the valve body, the drive device that is operated and controlled by the control device moves the valve body. By simply reciprocating, the opening amount of the opening in the intake pipe peripheral wall can be increased or decreased, and the effective length of the intake pipe can be changed as appropriate depending on the engine speed. It is possible to obtain high output and to reduce the reduction ratio of the vehicle's speed reducer, which can contribute to improving fuel economy and power performance. In particular, the valve body is configured to intersect obliquely with the longitudinal side edge of the opening in the peripheral wall of the intake pipe in order to increase the opening amount of the opening in the peripheral wall of the intake pipe from the upstream side in the intake direction by forward movement of the intake pipe in a direction orthogonal to the intake direction. Since the valve body has a sloped side edge that allows the valve body to move back and forth, the ratio of the intake pipe length adjustment stroke to the reciprocating stroke of the valve body can be increased. Since it can be changed quickly, the length of the intake pipe can be changed with good responsiveness in response to changes in engine speed. Moreover, since the operating stroke of the drive device that drives the valve body can be shortened, the drive device itself can be easily downsized, and even if the adjustment stroke of the intake pipe length becomes long, this allows the maximum overall length of the intake pipe to be reduced. There is no need to set it particularly long,
As a result of the above, the present invention can greatly contribute to downsizing of the intake device as a whole.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view of main parts of an intake and exhaust system of an internal combustion engine according to an embodiment of the present invention, and FIG.
Figure 3 is a vertical cross-sectional view taken along the - line in Figure 2, and Figure 4 shows an example of changes in volumetric efficiency with respect to engine speed. It is a graph. 5 ₁ to 5 ₄ ... Intake pipe, 5a ₁ to 5a ₄ ... Opening part,
18... Drive device, 21... Control device, C... Intake pipe length changing device, _v1 to _v4 ... Valve body, _s1 to _s4 ... Inclined side edge.

Claims (1)

[Claims] 1. An intake pipe length changing device C for changing the substantial length of the intake pipes 5 ₁ to 5 ₄ , and the intake pipes 5 ₁ to 5 ₄
In the intake system for an internal combustion engine, the intake pipe length changing device C includes a control device 21 for controlling the operation of the intake pipe length changing device C in order to change the substantial length of the intake pipe length changing device C according to the rotational speed of the engine. Intake pipe 5 ₁
Openings 5a 1 to 5a ₄ provided in the peripheral wall of the intake pipes 5 ₁ to 5 ₄ and extending in the intake direction of the intake pipes 5 ₁ to 5 ₄ ;
₁ to 5 ₄ so as to be able to reciprocate in a direction perpendicular to the intake direction, and the forward movement opens the openings 5 a ₁ to 5 4 .
Valve bodies v _{1 to v 4} have inclined side edges s ₁ to s ₄ that can diagonally intersect with the longitudinal side edges of the openings 5 a 1 to 5 a _{4 in order to increase the opening amount of the openings 5 a 4 from the upstream} side in the intake direction. , the operation of which is controlled by the control device 21 to cause the valve body v ₁ to
An intake system for an internal combustion engine having a variable length intake pipe, characterized by comprising a drive device 18 for reciprocating the _V4 .