JPH0625641Y2 - Intake device for internal combustion engine with turbocharger - Google Patents

Description

TECHNICAL FIELD The present invention relates to an intake system for a turbocharged internal combustion engine in which a compressor of a turbocharger is provided upstream of a throttle valve.

2. Description of the Related Art FIG. 6 shows a configuration example of a conventional intake device for an internal combustion engine with a turbocharger.

In the figure, 1 is an internal combustion engine, 2 is an intake manifold, and a throttle valve 3 is disposed on the inlet side of its collector 2a. The collector 2a is connected to the discharge side of the compressor 6 of the turbocharger 5 via the first intake passage 4. On the suction side of the compressor 6, a second
The intake passage 7 is connected and the second intake passage 7 is connected.
An air cleaner 8 and an air flow meter 9 are provided on the upstream side. In the illustrated example, the hot wire air flow meter 9
Is used.

A fuel injection valve 10 is provided at each branch of the intake manifold 2 to supply fuel to each cylinder.

The turbine 11 of the turbocharger 5 is installed in the middle of the exhaust passage 12 of the internal combustion engine 1, and a wastegate valve 13 is provided upstream of the turbine 11 so as to allow a part of the exhaust gas to escape according to the boost pressure. It is provided.

By the way, in the case where the compressor 6 of the turbocharger 5 is arranged on the upstream side of the throttle valve 3 as described above, when the throttle valve 3 is rapidly closed to decelerate the internal combustion engine 1 from the supercharging state, the compressor 6 Since 6 continues to rotate due to its inertial force and residual exhaust pressure, the pressure in the first intake passage 4 between them rapidly increases. At the same time, the amount of air flowing into the compressor 6 sharply decreases, so that surging occurs and pulsation occurs on the downstream side of the compressor 6. That is, the pressure in the first intake passage 4 becomes extremely high during deceleration as shown by the solid line in FIG. 7, and is accompanied by severe pulsation. Therefore, there is a problem that a large intake noise is generated during deceleration. Further, when the pressure on the downstream side of the compressor 6 increases, the rotation of the compressor 6 decreases rapidly, and the responsiveness at the time of reacceleration deteriorates.

Therefore, in order to deal with such problems during deceleration,
Various intake devices provided with a recirculation mechanism have been proposed.

That is, as shown in FIG. 6, it branches from the first intake passage 4 downstream of the compressor 6 to the second intake passage 4 upstream of the compressor 6.
An intake return passage 14 reaching the intake passage is provided, and a recirculation valve 15 that opens and closes the intake return passage 14 is provided, for example, on the inlet side thereof. The recirculation valve 15 is configured to be opened and closed by, for example, a diaphragm type actuator 16, and a negative pressure chamber of the actuator 16 has a pressure introducing passage 17 therein.
Through the inside of the intake manifold 2.

According to this configuration, during deceleration of the engine, the recirculation valve 15 is opened by the negative pressure that develops downstream of the throttle valve 3, and the intake air pressurized by the compressor 6 flows to the upstream side of the compressor 6 via the intake return passage 14. And circulate. Therefore, as shown by the broken line in FIG. 7, a rapid pressure increase downstream of the compressor 6 is weakened and surging is suppressed. At the same time, the resistance of the intake air exerted on the compressor 6 is reduced, and a relatively high rotation speed can be maintained even during deceleration.

An intake device equipped with a recirculation valve is disclosed in, for example, Japanese Patent Publication No. 56-10452.

However, even if the recirculation valve 15 is provided to circulate intake air upstream of the compressor 6 during deceleration as described above, pressure rise and pulsation downstream of the compressor 6 are completely prevented. You cannot do it. Moreover, since these pressure fluctuations flow back to the air cleaner 8 side and leak to the outside, the intake noise generated during deceleration cannot be sufficiently suppressed.

Further, in the case where the intake air amount is measured by the air flow meter 9 such as a hot wire type as in the illustrated example, there is a problem that a measurement error occurs due to the reverse flow of intake air. In particular, since the intake air amount is measured so as to be larger than the actual amount, the fuel injection amount may be excessive and the afterburn of the engine may be caused.

Therefore, the present invention is directed to an internal combustion engine with a turbocharger, in which a compressor of a turbocharger is provided on the upstream side of a throttle valve and a recirculation mechanism that returns intake air from the compressor downstream to the upstream when the engine is decelerated. In an intake device of an engine, a first negative pressure type actuator that opens a recirculation valve of the recirculation mechanism when an engine intake negative pressure is introduced and a predetermined negative pressure acts, and an intake air of the recirculation mechanism. A shut-off valve that opens and closes the intake passage upstream of the return port and an engine suction negative pressure are introduced, and the shut-off valve is closed when negative pressure acts, and at a negative pressure larger than that of the first negative pressure type actuator. A second negative pressure type actuator whose operating pressure is set to operate. It has a feature.

Operation In the above configuration, at the time of deceleration, the intake passage is closed by the shut-off valve slightly upstream of the opening operation of the recirculation valve on the upstream side of the compressor, specifically, on the upstream side of the intake return port of the recirculation mechanism. Therefore, the pressure fluctuation generated on the downstream side of the compressor is not transmitted to the outside.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a configuration explanatory view showing a configuration of an intake device according to the present invention. Since the basic structure is the same as that shown in FIG. 6 described above, the same reference numerals are given to the same parts, and the duplicated description will be omitted.

This intake device is provided with the recirculation valve 15 described above, and during deceleration when the throttle valve 3 is closed, the intake device returns from the first intake passage 4 downstream of the compressor 6 to the second intake passage upstream of the compressor 6. The intake air is returned to the intake passage 7. Here, although the tip of the intake return passage 14 is connected to an appropriate position of the second intake passage 7, the intake return opening 14 through which the intake return passage 14 opens
A shutoff valve 21 that opens and closes the second intake passage 7 is arranged at a position upstream of a and downstream of the air flow meter 9.

The shutoff valve 21 is, for example, a butterfly valve,
It is driven to open and close by a diaphragm type actuator 22. For details, refer to the above-mentioned diaphragm type actuator 2
If the inside of the second negative pressure chamber 22a is atmospheric pressure, the shutoff valve 21 is opened, and is closed when a predetermined negative pressure is introduced into the negative pressure type 22a. The negative pressure type 22a is
It is connected to the first port 23 a of the three-way solenoid valve 23 via the passage 24. The second port 23b of the three-way solenoid valve 23 is connected to the intake manifold 2 via the negative pressure introducing passage 25.
And the third port 23c is connected to the downstream side of the air cleaner 8 via the atmosphere introduction passage 26. The three-way solenoid valve 23 is configured so that the passage 24 communicates with the atmosphere introduction passage 26 side when it is OFF, and the passage 24 communicates with the negative pressure introduction passage 25 side when it is ON. Further, a throttle valve switch 27 is attached to the throttle valve 3 to detect the closing operation of the throttle valve 3. This throttle switch 2
7 indicates that when the throttle valve 3 is fully closed, that is, at the idle opening degree,
It emits an ON signal.

A control unit 28 controls ON / OFF of the three-way solenoid valve 23. The control unit 28 is composed of, for example, a microcomputer that operates according to a predetermined program. And
The control unit 28 is supplied with a detection signal of a rotation speed sensor 29 for detecting the engine rotation speed and a detection signal of the throttle valve switch 27.

Specifically, the control unit 28 controls ON / OFF of the three-way solenoid valve 23 according to the flowchart shown in FIG. That is, the throttle switch 2
If 7 is ON (that is, the throttle valve 3 is fully closed) and the engine speed N is equal to or more than the predetermined value N ₁ , it is determined that the deceleration is from the supercharging state, and the three-way solenoid valve 23 is turned ON. (Steps 1, 2, 3). In other cases, that is, when the throttle valve switch 27 is OFF or the engine speed N is equal to or less than the predetermined value N ₁ , the three-way solenoid valve 23 is turned OFF (step 4).

On the other hand, the operating pressure of the diaphragm actuator 16 that opens the recirculation valve 15 and the diaphragm actuator 22 that closes the shutoff valve 21.
Is set to a value slightly different from the operating pressure of. Second
The figure shows the pressure characteristics of the diaphragm actuator 16 for the recirculation valve 15.
When the negative pressure becomes stronger than V _{1, the} recirculation valve 15 starts to open, and fully opens at the stage of V ₂ . Further, FIG. 3 shows a diaphragm type actuator 22 for the shutoff valve 21.
The shutoff valve 21 starts to close at a negative pressure of V ₁ + a, which is closer to a vacuum than the operation start pressure V ₁ of the recirculation valve 15, and V
₂ becomes fully closed at a negative pressure of V _{2 +} b close to the more vacuum than.
The pressure difference a and b between the two is set to, for example, about 50 mmHg.

Next, the operation of the above configuration will be described.

When the throttle valve 3 is closed while the internal combustion engine 1 is operating at a rotation speed of the predetermined rotation speed N ₁ or higher, the three-way solenoid valve 23 is turned on according to the above-described flowchart, and the inside of the intake manifold 2 and the diaphragm actuator 22 are operated. Of the negative pressure chamber 22a. Further, in the intake manifold 2, a negative pressure develops due to the closing of the throttle valve 3. Therefore, this negative pressure is guided to the diaphragm actuator 22 for the shutoff valve 21 and the diaphragm actuator 16 for the recirculation valve 15, respectively, and the recirculation valve 15 is opened and the shutoff valve 21 is closed. .

Therefore, the intake air pressurized by the compressor 6 circulates in the closed circuit which is completely cut off from the outside.
As shown by the alternate long and short dash line in the figure, the pressure increase immediately after deceleration on the downstream side of the compressor 6 is weakened and the surging is suppressed. By shutting off the second intake passage 7 by the shutoff valve 21, pressure fluctuations on the downstream side of the compressor 6 do not leak outside, and intake noise during deceleration can be reliably prevented. Further, since the shutoff valve 21 is located on the downstream side of the air flow meter 9, it is possible to prevent a measurement error due to a backflow of intake air.

Since the recirculation valve 15 and the shutoff valve 21 have different operating pressure settings as described above,
First, the recirculation valve 15 opens, and the shutoff valve 21 closes after a slight delay. Therefore, there is no fear that the upstream side of the compressor 6 becomes a negative pressure and promotes surging. Further, the reduction in the rotation speed of the compressor 6 is suppressed, and it is possible to prepare for re-acceleration.

On the other hand, when the throttle valve 3 is opened again and re-accelerated from such a decelerated state, the three-way solenoid valve 23 is immediately turned off based on the above-mentioned flowchart, and the negative pressure chamber 22a of the diaphragm type actuator 22 is exposed to the atmosphere. Open to the public. Therefore, the shutoff valve 21 is immediately opened, and the supply of intake air to the internal combustion engine 1 is restarted. Further, as a result, the negative pressure in the intake manifold 2 is weakened, so that the recirculation valve 15 closes slightly after the shutoff valve 21 opens. That is, since the shut-off valve 21 is opened almost simultaneously with the start of reacceleration and always before the closing operation of the recirculation valve 15, the acceleration response is not impaired, and the occurrence of surging is prevented. still,
As described above, since unnecessary pressure rise and surging are prevented in the downstream of the compressor 6 during deceleration, the decrease in the rotational speed of the compressor 6 during deceleration becomes more gradual, and the response at the time of reacceleration improves. .

As is apparent from the above description, according to the intake device for the internal combustion engine with the turbocharger according to the present invention, the recirculation mechanism is activated during engine deceleration, and at the same time, the intake passage is closed on the upstream side of the compressor. Pressure fluctuations generated on the downstream side of the compressor do not leak to the outside,
It is possible to reliably prevent intake noise during deceleration, which is a problem in an internal combustion engine with a turbocharger. In particular, the operating pressures of the first negative pressure type actuator for opening the recirculation valve and the second negative pressure type actuator for closing the shutoff valve are made different, and the shutoff valve is closed with a slight delay. Surging can be reliably prevented, and a decrease in the number of revolutions of the compressor can be suppressed. Further, at the time of reacceleration, the shutoff valve is opened before the recirculation valve is closed, which is advantageous in terms of acceleration response and surging prevention.

[Brief description of drawings]

FIG. 1 is a configuration explanatory view showing an embodiment of an intake device according to the present invention, FIG. 2 is a characteristic diagram showing a pressure characteristic of a recirculation valve, and FIG. 3 is a characteristic diagram showing a pressure characteristic of a shutoff valve. FIG. 4 is a flow chart showing an outline of control in the control unit, and FIG. 5 is a characteristic diagram showing a pressure change on the compressor downstream side in this embodiment in comparison with a conventional one not equipped with a recirculation valve and a shutoff valve, FIG. 6 is a structural explanatory view showing a structural example of a conventional intake device having a recirculation valve, and FIG.
The figure is a characteristic diagram showing a change in pressure on the downstream side of the compressor in an intake system equipped with this recirculation valve in comparison with that without the recirculation valve. 1 ... internal combustion engine, 3 ... throttle valve, 6 ... compressor, 9
...... Air flow meter, 14 ...... Intake return passage, 15 ......
Recirculation valve, 21 ... Shut-off valve, 23 ...
… Three-way solenoid valve, 27 …… Throttle valve, 28 …… Control unit.

Claims (1)

[Scope of utility model registration request] 1. An intake system for an internal combustion engine with a turbocharger, wherein a turbocharger compressor is provided on the upstream side of a throttle valve, and a recirculation mechanism is provided for returning intake air from the compressor downstream to upstream when the engine is decelerated. A first negative pressure type actuator for opening a recirculation valve of the recirculation mechanism when a negative pressure is introduced and a predetermined negative pressure action, and an intake passage upstream of an intake return port of the recirculation mechanism. And a shut-off valve for opening and closing the shut-off valve and an engine suction negative pressure are introduced, and the shut-off valve is closed when negative pressure acts, and the working pressure is set so that the shut-off valve operates at a negative pressure larger than that of the first negative pressure type actuator. Internal combustion engine with a turbocharger Intake system of Seki.