JP2984044B2 - Engine intake system - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an intake system for an engine, and more particularly, to an intake system for an engine, in which air is taken into a combustion chamber via a plurality of intake passages, and a part of the plurality of intake passages is partially removed. The present invention relates to an intake device for an engine, which is appropriately closed and controlled by an intake passage variable unit.

<< Conventional Technology >> As an intake device for this type of engine, for example, there is one disclosed in Japanese Patent Application Laid-Open No. 60-216031.
Although applied to a rotary piston engine, two intake passages, a low-load intake port and a high-load supply port, are provided, and these low-load intake ports and high-load intake ports are provided in accordance with the operation state of the engine. It is designed to be switchable with the intake port.

By the way, there has been proposed a reciprocating engine in which air is drawn into a combustion chamber through a plurality of intake passages. For example, in the engine shown in FIG. The intake passage is branched into a primary intake passage 3 and a secondary intake passage 4,
These intake passages 3 and 4 are respectively connected to intake ports 5a and 5b provided two by two for each cylinder.

The primary intake passage 3 and the secondary intake passage 4 are connected to each other at two branch portions.
Two throttle valves 6a, 6b are provided, and an opening / closing valve 7 is provided in the secondary intake passage 4 on the downstream side of the throttle valve 6b.

The opening / closing valve 7 is closed in a low engine load and low engine speed range. At this time, the engine is sucked only from the primary intake passage 3. A fuel injection valve 8 is provided in the passage 3, and is supplied to the combustion chamber as an air-fuel mixture with the fuel injected from the fuel injection valve 8.

Further, the opening / closing valve 7 is opened in a high-load, high-speed region where a large amount of intake air is required, so that a large amount of air can be supplied to the engine from the secondary intake passage 4 into the combustion chamber.

In other words, in the low load and low rotation region where the intake air amount is small, the secondary intake passage 4 is closed, so that the intake flow velocity in the primary intake passage 3 is increased and the intake air is sucked into the combustion chamber. The air and the air are sufficiently stirred. Further, in a high-load, high-rotation region where the amount of intake air is large, the intake resistance is reduced by opening the secondary intake passage 4 to intake air.

FIG. 6 shows the torque characteristic (P) when the air is taken only from the primary (Pry) intake passage 3 and the open / close valve 7.
And the torque characteristic (P + S) when the intake valve 4 is opened and air is also taken in from the secondary (Sry) intake passage 4, so that the opening / closing of the opening / closing valve 7 is controlled by using the intersection X of these characteristics P and P + S as a switching point. Has become.

<< Problems to be Solved by the Invention >> In such a conventional intake system for an engine, it is ideal that the open / close valve 7 is switched at the point X in FIG. Is switched via an actuator (not shown). Therefore, the switching time of the opening / closing valve 7 may deviate from the point X due to a delay in the operation of the actuator.

For example, when the engine and the drive train are not connected,
If the speed drops rapidly due to the throttle valve closing,
The closing operation of the on-off valve 7 cannot follow the rapid decrease in rotation, and the return of the flow velocity of the first intake passage is delayed, resulting in engine stall or output reduction.

As described above, when closing the opening / closing valve 7 due to the operation delay of the actuator that switches the opening / closing valve 7, the rise of the intake flow velocity on the primary intake passage 3 side is delayed, and the output of the engine is reduced. There was a problem such as that

Accordingly, the present invention has been made in view of such a conventional problem, and provides an engine intake device capable of correcting an operation delay of an actuator for operating an opening / closing valve and sufficiently generating an original engine output. Aim.

<< Means for Solving the Problems >> In order to achieve this object, the present invention relates to a first embodiment which is connected to a combustion chamber and is set to a normally open state as shown in FIG.
An intake passage b, a second intake passage c that is opened at a predetermined rotational speed of the engine or more and closed at a lower rotational speed,
An intake system for an engine having a fuel injection valve g provided in an intake passage b.
A no-load detecting means i for detecting a disconnected state between the engine and the drive system, a first intake passage b and a second intake passage c
And an intake passage changing means d for setting the second intake passage c to a closed state when the throttle opening is equal to or less than a predetermined throttle opening and no load is detected.

<< Operation >> In the intake system for an engine of the present invention having the above configuration, in the configuration shown in FIG. 1, the intake passage variable means d detects the second intake passage c when the throttle opening is equal to or less than the predetermined opening degree and no load is detected. Can be closed.
When the engine speed is rapidly decreased, the flow velocity of the first intake passage b is quickly returned, and the fuel injected from the fuel injection valve g can be sufficiently stirred, so that the engine output becomes excessive. Significant reduction can be prevented.

<< Example >> Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 2 shows an embodiment of an engine intake device 10a according to the present invention, and describes an example in which the present invention is applied to an engine 12 having four cylinders.

That is, a twin turbo supercharger 14 is provided in an intake system of the engine 12, and an intake passage 16 is provided through the supercharger 14.
Air is introduced into the air.

The intake passage 16 is branched into two from the middle, one of which is a primary intake passage 18 as a first intake passage, and the other is a secondary intake passage 20 as a second intake passage.

On the other hand, each cylinder 22, 22,... Of the engine 12 is provided with two intake ports 24a, 24b and exhaust ports 26a, 26b, respectively, and the primary intake passage 18 is connected to one intake port 24a, and The secondary intake passage 2
0 is connected to the other intake port 24b.

By the way, the primary intake passage 18 has a smaller cross-sectional area than the secondary intake passage 20 so that a large intake flow velocity can be secured, and the primary intake passage 18 is used as a main passage. Can be

The secondary intake passage 20 has a relatively large cross-sectional area and a small intake resistance, and the primary intake passage 20 is used in a high-load, high-speed range.

The primary intake passage 18 and the secondary intake passage
The 20 branch section includes a primary throttle valve 28 and a secondary throttle valve 30 that are interlocked with each other.
The throttle valve 28, 30 is controlled in opening in conjunction with the accelerator pedal to control the amount of intake air.

In the vicinity of the downstream side of the throttle valves 28 and 30, a primary intake passage 18 and a secondary intake passage 20 are provided.
Is opened.

By the way, first fuel injection valves 34, 34,... Are provided near the upstream side of the intake ports 24a, 24a. , 34 ... are agitated by the intake air in the primary intake passage 18, and this is supplied to each of the cylinders 22, 22, ... as an air-fuel mixture.

On the other hand, the secondary intake passage 20 includes the communication passage
A shutter valve as an open / close valve near the downstream side of 32
When the shutter valve 36 is set to the open state, the shutter valve 36 is set to the open state, and the shutter valve 36 is set to the closed state, and the shutter valve 36 is set to the closed state to set the air flow to the secondary intake path 20. Is cut off.

The shutter valve 36 is linked to a diaphragm 38 driven by a negative pressure generated on the downstream side of the throttle valve 28, and is opened and closed by the diaphragm 38.

Further, a negative pressure passage for introducing a negative pressure to the diaphragm 38.
A duty-controlled solenoid valve 42 is provided in the middle of 40, and the solenoid valve 42 can control the negative pressure value supplied to the diaphragm 38.

The shutter valve 36, the diaphragm 38, and the solenoid valve 42 constitute an intake passage changing means 44. A negative pressure downstream of the throttle valve 28 on the primary intake passage 18 side is introduced into the diaphragm 38.

Further, an engine speed signal, a throttle opening signal, and a gear switch signal are input to a control unit 46a that outputs control signals to the solenoid valve 42 and the first fuel injection valves 34, 34,. The control signal is calculated based on the control signal.

Here, in the opening / closing area of the shutter valve 36 by the intake passage changing means 44, as shown in FIG. 3, a position where the engine rotation speed becomes a predetermined value a (rpm) is a switching line B. In the rotation speed region below B, the shutter valve 36 is closed (the valve closing region is indicated by oblique lines), and air is taken in only from the primary intake passage 18.

Further, when the rotation speed is equal to or higher than the rotation speed of the switching line B, the shutter valve 36 is opened so that air is taken in from both the primary intake passage 18 and the secondary intake passage 20.

In the intake device 10a of this embodiment having such a configuration, the control executed by the control unit 46a is processed according to the flowchart shown in FIG.

That is, in the flowchart, first, at step 110
, The engine speed (rpm) is read. In the next step 111, it is determined whether or not the engine speed read in step 110 exceeds the predetermined speed a (rpm) serving as the switching line B. .

If the engine speed is in the low speed region not exceeding a, the routine proceeds to step 112, where the shutter valve 3
6 is closed.

On the other hand, if the engine rotation speed exceeds the predetermined rotation speed a, the process proceeds to step 113 to read a gear switch signal, and in the next step 114, it is determined whether or not the vehicle is in a no-load (N / L) state based on the gear switch signal. Is determined.

At this time, if it is determined that the vehicle is in the no-load state, the routine proceeds to step 115, where the throttle opening (TVO) is read. In the next step 116, it is determined whether or not the throttle opening exceeds the predetermined opening b. If the throttle opening is equal to or smaller than the predetermined opening b, the routine proceeds to step 112, where the shutter valve 36 is set to a closed state.

On the other hand, if the opening degree exceeds the predetermined opening b in step 116, the process proceeds to step 117, where the shutter valve 36 is set to the open state.

Even if it is determined in step 114 that the vehicle is not in the no-load state, the process jumps to step 117 to set the shutter valve 36 to the open state.

Therefore, in this embodiment, as shown by a mesh portion in FIG. 3, when the throttle opening is equal to or less than the predetermined opening b and the engine is in the no-load state, the engine rotation speed is equal to or higher than the predetermined rotation speed a. Even if there is a shutter valve 112
Can be closed to take in air only from the primary intake passage 18.

That is, when the vehicle rapidly decreases during no-load fully-closed deceleration and the rotation rapidly decreases, and when the opening and closing of the shutter valve 36 is determined on the switching line B determined only by the predetermined rotation speed a, the shutter valve 36 Air-fuel ratio (A / F) due to delay in switching time from open state to closed state and delay in flow velocity return of primary intake passage 18
, The engine stalls or the output decreases.

However, when the vehicle is in the no-load state at a predetermined throttle opening b or less as in the present embodiment, the shutter speed is closed before the rotation speed is reduced to the predetermined rotation speed a by closing the shutter valve 36. When the rotational speed is actually decreased to the predetermined rotational speed a, the flow velocity of the primary intake passage 18 can be sufficiently restored.

For this reason, the fuel injected from the first fuel injection valves 34, 34... Is sufficiently agitated to prevent misfire, and the acceleration performance from the low rotation speed region is significantly improved.

Further, in this embodiment, the control for closing the shutter valve 36 can be performed by detecting only the no load regardless of the throttle opening, and in this case, when performing the downshift during the high-speed operation, The output can be prevented from lowering.

That is, when downshifting during high-speed driving, first, disengage the clutch and set it to the no-load state to perform a downshift, then perform engine idling to reduce the engine speed in the downshift state. Raise, and
Smooth downshifting is performed by connecting the clutch when the engine speed increases, but by closing the shutter valve 36 only in the no-load state, the fuel is sufficiently agitated as described above. It is possible to quickly start the engine rotation.

<< Effects of the Invention >> As described above, in the intake system for an engine according to the first aspect of the present invention, the intake passage variable means closes the second intake passage when the throttle opening is equal to or less than a predetermined opening degree and no load is detected. Therefore, when the engine speed is rapidly decreased, the flow rate of the first intake passage is quickly returned to sufficiently stir the injected fuel, and the output of the engine is excessively greatly reduced. Can be prevented.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a concept of an intake device for an engine according to the present invention, FIG. 2 is a schematic configuration diagram of an intake device for an engine showing an embodiment of the present invention, and FIG. FIG. 4 is a characteristic diagram showing a switching line of the intake passage, FIG. 4 is a flowchart showing one processing example for executing control of the embodiment of the present invention, FIG. 5 is a schematic configuration diagram showing a conventional intake device, FIG. 6 is a torque characteristic diagram with respect to the engine rotational speed obtained by the conventional intake device. 10a intake device 12 engine 14 supercharger 16 intake passage 18 primary intake passage (first intake passage) 20 secondary intake passage (second intake passage) 22 cylinder 24a, 24b Intake ports 26a, 26b Exhaust ports 28 Primary throttle valve 30 Secondary throttle valve 34 First fuel injection valve 36 Shutter valve (switching valve) 38 Diaphragm 42 Solenoid valve 44 …… Intake path variable means 46a …… Control unit

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yoshihiro Hidehira 3-1 Shinchi, Fuchu-cho, Aki-gun, Hiroshima Mazda Co., Ltd. (72) Inventor Hiroshi Nose 3-1 Shinchi, Fuchu-cho, Aki-gun, Hiroshima Matsu (56) References JP-A-62-17318 (JP, A) JP-A-62-228624 (JP, A) JP-A-64-29225 (JP, U) (58) Fields investigated (Int .Cl. ⁶ , DB name) F02B 27/02 F02D 45/00 F02D 41/34

Claims (1)

(57) [Claims] A first intake passage which is communicated with a combustion chamber and is set to a normally open state;
A second intake passage that is closed at a lower rotational speed,
An intake system for an engine, comprising: a fuel injection valve provided in an intake passage; a throttle opening detecting unit; a no-load detecting unit for detecting a disconnected state between the engine and a driving system; a first intake passage and a second intake passage An intake system for an engine, comprising: intake passage variable means for setting the second intake passage to a closed state when the throttle opening is equal to or less than a predetermined throttle opening and no load is detected in a passage open region.