JP4889427B2 - Intake air adjustment system for internal combustion engine - Google Patents

Description

  The present invention relates to an intake air adjustment system for an internal combustion engine including a supercharger such as a turbocharger.

  Conventionally, in an internal combustion engine equipped with an intake / exhaust valve mounted on a vehicle such as an automobile, there are a state in which the intake valve is opened and a state in which the exhaust valve is opened in order to improve combustion efficiency. The valve timing may be set to occur temporarily. When such an internal combustion engine is stopped, the intake valve and the exhaust valve may be opened. In this case, the exhaust gas staying in the exhaust system flows back to the intake system such as the intake manifold, throttle body, intake pipe, and air cleaner through the cylinder due to wind or the like while the internal combustion engine is stopped. Sometimes. In this way, if the exhaust gas flows into the intake system and is full, the amount of oxygen in the intake air at the time of start-up decreases, so startability may deteriorate. This phenomenon may be significant when a turbocharger is provided and the arrangement of the exhaust system and the intake system becomes long due to the arrangement of the internal combustion engine in the vehicle.

In such an internal combustion engine, for example, as described in Patent Document 1, exhaust gas that has accumulated in an intake system can be scavenged when the internal combustion engine is stopped. That is, this Patent Document 1 includes a bypass passage provided with a supercharger in the intake system and a bypass valve that bypasses the supercharger, and is bypassed by opening the bypass valve when the engine is stopped. The exhaust gas staying in the intake system is scavenged through the passage.
JP 2005-140092 A

  By the way, the above-mentioned configuration is such that one end of the bypass passage is connected downstream of the throttle valve and the other end is connected to the intake manifold, so the scavenging efficiency is low and the startability at the next start is improved. It was difficult to do. That is, although the bypass passage itself has a smaller passage resistance than the other main intake passages, the main intake passage to which the bypass passage is connected has a large intake resistance, so that the bypass passage is not completely scavenged. is there. In addition, since the internal combustion engine is stopped, the throttle valve is almost closed, and even if an attempt is made to scavenge toward the upstream side of the throttle valve, since the opening area is small, the exhaust gas located downstream of the throttle valve. Is less likely to flow out upstream of the throttle valve via the throttle valve. Accordingly, incomplete scavenging of the exhaust gas affects the next startability.

  Therefore, the present invention aims to eliminate such problems.

That is, the intake air adjustment system for an internal combustion engine of the invention according to claim 1 of the present application is provided with a supercharger that is provided upstream of a throttle valve provided in an intake passage and supercharges intake air into a combustion chamber. In the engine, an intake bypass passage that allows communication between the upstream and downstream of the compressor of the turbocharger and an exhaust bypass passage that enables communication between the upstream and downstream of the turbine of the turbocharger are provided . the intake bypass valve for opening and closing the intake bypass passage, also the exhaust bypass passage provided an exhaust bypass valve for opening and closing the exhaust bypass passage, introducing the boost pressure from the throttle valve downstream more exhaust bypass valve to open and close the opening regulating valve And a supercharging pressure adjusting passage through which atmospheric pressure can be introduced, and an opening degree adjusting valve so that the upstream of the supercharger communicates with the downstream of the throttle valve when the internal combustion engine is started Wherein the opening a predetermined time.

  According to such a configuration, when the opening adjustment valve is opened when starting the internal combustion engine, fresh air is supplied to the internal combustion engine through the supercharging pressure adjustment passage while bypassing the supercharger and the throttle valve. It will be in the state which can be supplied. That is, when the opening adjustment valve is opened, air is supplied to the internal combustion engine at the time of starting without going through the supercharger and the throttle valve. For this reason, even if the exhaust gas in the previous operation stays in the intake passage upstream of the supercharger and the throttle valve, fresh air flows into the combustion chamber through the supercharging pressure adjustment passage. Therefore, by adjusting the amount of air flowing through the opening adjustment valve, it is possible to supply fresh air required at the time of start-up, and because the amount of air increases, the engine speed of the internal combustion engine blows. It is possible to prevent it from going up.

  An intake air adjustment system for an internal combustion engine according to a fourth aspect of the present invention is an internal combustion engine comprising a supercharger that is provided upstream of a throttle valve provided in an intake passage and supercharges intake air into a combustion chamber. In an engine, an intake bypass passage that enables communication between the upstream and downstream of the compressor of the turbocharger is provided, and an intake bypass valve that opens and closes the intake bypass passage is provided in the intake bypass passage, and an opening adjustment valve that adjusts the air amount Provided with a supercharging pressure adjusting passage communicating with the upstream of the supercharger and the downstream of the throttle valve, and the opening degree so that the upstream of the supercharger communicates with the downstream of the throttle valve when the internal combustion engine is started. The adjusting valve is opened for a certain time.

  According to such a configuration, since the supercharging pressure adjusting passage communicates with the upstream of the supercharger and the downstream of the throttle valve, the opening adjusting valve is opened and the intake bypass is operated during the operation of the internal combustion engine. The supercharging pressure can be adjusted by opening and closing the valve. In addition, when the internal combustion engine is started, by opening the opening adjustment valve, a large amount of fresh air can be supplied from the turbocharger upstream to the throttle valve downstream via the supercharging pressure adjustment passage. Become. In addition, during idle operation after startup, the air necessary for idle operation is appropriately supplied to the internal combustion engine downstream of the throttle valve by adjusting the opening of the opening adjustment valve, in other words, with the throttle valve bypassed. It becomes possible to do.

  The present invention is configured as described above. Since fresh air can be supplied to the combustion chamber of the internal combustion engine at the time of starting, the startability can be improved, and a large amount of air can be supplied to the internal combustion engine. By controlling the supply, it is possible to prevent the rotation of the internal combustion engine from blowing up.

[Example 1]
Hereinafter, an embodiment of the present invention will be described with reference to FIG.

A spark ignition type engine EG which is an internal combustion engine of the first embodiment includes an exhaust turbine supercharger (hereinafter referred to as a turbocharger) 1. This engine EG has an intake valve 2 and an exhaust valve 3, and is set with a so-called overlap period in which the intake valve 2 and the exhaust valve 3 are opened simultaneously. The engine EG is arranged at a position where the intake passage 7 extending from the air cleaner 4 to the surge tank 6 via the compressor 1c and the intercooler 5 of the turbocharger 1 becomes longer than a general one depending on the structure of the vehicle. is there. In the engine EG of this embodiment, an ISC bypass passage 9 that bypasses the throttle valve 8 is provided in order to control the intake air amount so as to control the engine speed during idle operation. 9 is provided with an ISCV (idle speed control valve) 10 for controlling the intake air amount. In addition, the operation of the engine EG is controlled by an electronic control device (not shown) including the control of the engine speed during idle operation. In order to detect the operating state of the engine EG, various sensors such as an O ₂ sensor, a rotation speed sensor, and a cooling water temperature sensor, an ISCV 10, and an electromagnetic VSV (vacuum switching valve) that is an opening adjustment valve described later. 11. A fuel injection valve (not shown) is electrically connected to the electronic control unit.

  As the turbocharger 1 itself, a well-known one in this field can be used. For example, in order to control the supercharging pressure, an exhaust bypass passage 1b that enables communication between the upstream and downstream of the turbine 1t is provided. It is preferable to include a waste gate 1w and an actuator 1a constituting an exhaust bypass valve that opens and closes the exhaust bypass passage. The waste gate 1w is opened and closed by an actuator 1a, and is configured such that a supercharging pressure and an atmospheric pressure can be applied to the actuator 1a by adjusting a supercharging pressure by a supercharging pressure adjusting passage 12. .

  One end of the boost pressure adjusting passage 12 is connected to an air cleaner 4 (which may be a pipe line close to the air cleaner 4 to the inlet of the compressor 1c), and the other end is a surge downstream of the throttle valve 8. The tank 6 is connected to each of the tanks 6 and branched from an intermediate portion thereof to be connected to the actuator 1a. A VSV 11 is provided between one end and a branching portion to the actuator 1a, and the VSV 11 is opened or closed to apply a supercharging pressure or an atmospheric pressure to the actuator 1a. Since the supercharging pressure adjusting passage 12 only needs to allow air for controlling the actuator 1 a to flow therethrough, the inner diameter of the passage is set smaller than that of the ISC bypass passage 9. Therefore, even when the VSV 11 is fully opened, a large amount of air as in the case of controlling idle operation is not discharged to the outside from the surge tank 6, or vice versa.

  On the other hand, on the compressor 1c side of the turbocharger 1, a supercharging pressure bypass mechanism 13 that bypasses the compressor 1t is provided. The supercharging pressure bypass mechanism 13 includes an intake bypass passage 13b that allows communication between the upstream and downstream of the compressor 1t, an ABV (air bypass valve) 13v that is an intake bypass valve that opens and closes the intake bypass passage 13b, and a throttle valve. And a control air passage 13n that introduces a negative pressure into the ABV 13v when 10 is closed. When the throttle valve 8 is closed almost instantaneously and the supercharging pressure suddenly increases and exceeds a predetermined pressure, a negative pressure downstream of the throttle valve 8 is applied to the ABV 13v via the control air passage 13n. The pressure bypass circuit 13b connects the upstream of the compressor 1c and the downstream of the compressor 1c, and releases the pressure of the intake passage 7 between the throttle valve 8 and the compressor 1c to the atmosphere to control the boost pressure. Is.

  In such a configuration, when the engine EG is operated, the turbocharger 1 is operated, and the air that has passed through the air cleaner 4 is compressed by the compressor 1c. When supercharging the intake air, the electronic control unit opens the VSV 11 to bring the inside of the supercharging pressure adjusting passage 12 to atmospheric pressure. As a result, the actuator 1a closes the waste gate 1w. On the other hand, when the supercharging pressure exceeds the predetermined pressure and becomes too high, that is, when the electronic control unit determines that the engine speed exceeds the predetermined speed, the VSV 11 is closed and the supercharging pressure adjusting passage 12 is connected. Then, a supercharging pressure is applied to the actuator 1a to open the waste gate 1w.

  In the state where the engine EG is operated, the engine EG of this embodiment has an overlap period as described above. If the engine EG is stopped at a timing in the vicinity of this overlap period or during that period, both the intake valve 2 and the exhaust valve 3 are in an open state. Gas may flow back into the intake passage 7. When the exhaust gas flows back in this way, the exhaust gas staying in the intake passage 7 becomes the intake air at the next start-up, but in this first embodiment, the supercharging pressure adjustment passage Fresh air is supplied to the combustion chamber 14 via 12.

  Specifically, for example, when the ignition switch is turned on, the VSV 11 is opened. As a result, the supercharging pressure adjusting passage 12 directly communicates with the air cleaner 4 and the surge tank 6. That is, the supercharging pressure adjustment passage 12 communicates with the most upstream of the throttle valve 8 and also communicates with the downstream of the throttle valve. Thus, the intake air can be supplied to the combustion chamber 14 in a state where the intake passage 7 between the outlet of the compressor 1c of the turbocharger 1 and the position of the throttle valve 8 is bypassed.

  The predetermined time for opening the VSV 11 is set in advance. For example, in the idling operation state at the time of starting, it is necessary for the exhaust gas staying over the entire area of the intake passage 7 to be replaced with fresh air. It only has to correspond to time. Alternatively, the amount of exhaust gas remaining in the intake passage 7 may be calculated corresponding to the time during which the engine EG has been stopped. In this case, the electronic control unit starts timing by the timer when the ignition switch is turned off, and then finishes timing when the ignition switch is turned on, while the engine EG is stopped. Measure the duration of. Then, based on the measured duration and the inner diameter of the supercharging pressure adjusting passage 12, the time for opening the VSV 11 is calculated. By configuring in this way and estimating the amount of exhaust gas flowing back to the intake passage 7 and opening the VSV 11, the amount of air supplied through the supercharging pressure adjustment passage 12 is set to an optimum amount required at the time of starting. Can be in quantity.

  When the engine EG is started in this state, fresh air flows into the combustion chamber via the supercharging pressure adjustment passage 12 by the open VSV 11. The intake air amount supplied to the combustion chamber 14 is the total amount of the air amount passing through the supercharging pressure adjustment passage 12 and the air amount supplied via the ISC bypass passage 9. Therefore, the ISCV 10 of the ISC bypass passage 9 is controlled to be closed, and the amount of air supplied to the combustion chamber 14 via the ISC bypass passage 9 is controlled. Thus, by reducing the amount of air through the ISC bypass passage 9, it is possible to suppress the engine speed from blowing up. Since the throttle valve 8 is closed, it is assumed that almost no air flows from the intake passage 7. Further, at the time of starting, the fuel supply amount or the fuel injection amount may be set based on the above-mentioned total amount of air, the temperature of the engine EG, the outside air temperature, and the like.

  In this way, the VSV 11 for opening and closing the waste gate 1w is used, and the supercharging pressure adjusting passage 12 provided with the VSV 11 communicates with the air cleaner 4 positioned upstream of the compressor 1c and the downstream of the throttle valve 8. As a result, fresh air can be supplied as much as necessary for starting, and a good starting can be realized. In addition, by controlling the amount of air from the ISC bypass passage 9, it is possible to prevent the engine speed from rapidly increasing (blowing).

[Example 2]
Next, a second embodiment of the present invention will be described with reference to FIG.

  The second embodiment is directed to an engine EG2 including a turbocharger 101 that is not provided with a waste gate and an intake passage 107 that is not provided with a bypass passage that bypasses the throttle valve 8. In this second embodiment, the intake air adjustment system is composed of a dedicated supercharging pressure adjustment passage 112 and an electromagnetic VSV 111 which is an opening adjustment valve.

  That is, the second embodiment is an engine EG2 provided with a turbocharger 101 that is provided upstream of the throttle valve 8 provided in the intake passage 107 and that supercharges intake air into the combustion chamber 14. A supercharging pressure adjustment passage 112 having one end connected upstream of the turbocharger 101 and the other end connected downstream of the throttle valve 8, and a VSV 111 provided in the supercharging pressure adjustment passage 112 to control the flow of working air. In addition, when starting the engine EG2, the VSV 111 is opened for a certain period of time so that the upstream side of the turbocharger 101 and the downstream side of the throttle valve 8 communicate with each other. Except for the structure of the supercharging pressure adjusting passage 112, the second embodiment is the same as the first embodiment described above.

  One end of the supercharging pressure adjustment passage 112 is connected to the intake passage 107 at a position near the inlet of the compressor 101 c of the turbocharger 101 or a position near the air cleaner 4, and the other end is an intake air at a position downstream of the throttle valve 8. Connected to the passage 107. In the second embodiment, this intake air adjustment system also serves as a supercharging pressure adjustment mechanism and an idle speed control mechanism of the turbocharger 101. Since it also serves as an idle speed control mechanism, the inner diameter of the supercharging pressure adjustment passage 112 is set larger than the inner diameter of the supercharging pressure adjustment passage described above, for example, as described in the first embodiment. What is necessary is just to set to the internal diameter etc. which are substantially equal to the internal diameter of the bypass passage 9 which was made. This is because the amount of air necessary for controlling the rotational speed during idle operation is larger than the amount of air necessary for controlling the above-described waste gate 1w.

  In the above configuration, when the engine EG2 is operated and the supercharging pressure exceeds the predetermined pressure, the VSV 111 is opened and a part of the supercharging pressure is released to the atmosphere. In this case, the control of the VSV 111 is performed when the electronic control unit (not shown) detects that the engine speed exceeds the predetermined speed based on the output signal of the speed sensor, as in the first embodiment. The VSV 111 is opened. When the VSV 111 is fully opened, the supercharging pressure decreases and the pressure of the intake air becomes atmospheric pressure. Therefore, a duty ratio indicating the ratio between the open state and the closed state is set, and the set duty ratio is The electronic control device controls the energization of the VSV 111 so that the opening degree becomes a predetermined opening degree.

  The control of the intake air amount during the idling operation is also performed by the VSV 111. Also in the rotational speed control during the idle operation, the VSV 111 is duty-controlled so that the engine rotational speed becomes the idle target rotational speed. Note that the duty ratio itself may be basically different between the case of the rotational speed control during idle operation and the case of the supercharging pressure control.

  When starting the engine EG2, the VSV 111 is almost fully opened, and fresh air flows directly from the upstream of the compressor 101c of the turbocharger 101 to the downstream of the throttle valve 8 of the intake passage 107. That is, by opening the VSV 111, the boost pressure adjusting passage 112 brings the compressor 101c upstream and the throttle valve 8 downstream into communication. Therefore, almost the entire area of the turbocharger 101c and the intake passage 107 is bypassed by the adjustment passage, and fresh air supplied through the supercharging pressure adjustment passage 112 is combusted as intake air at the start. Supplied to the chamber 14. In this case, the time during which the VSV 111 is opened may be set in the same manner as in the above-described embodiment.

  When the engine EG2 is stopped, the exhaust gas remaining in the combustion chamber 14 and the exhaust gas remaining in the exhaust system including the turbocharger 101 flow back into the intake passage 107 via the opened intake valve 2. Even if the air stays, fresh air can be supplied to the combustion chamber 14 through the supercharging pressure adjustment passage 112 at the time of start-up, so that startability can be improved. In addition, by adopting such a configuration, it is not necessary to provide a waste gate in the turbocharger 101. Accordingly, the waste gate control mechanism can be reduced, and the turbocharger 101 itself and the surrounding structure are simplified. Can be In addition to this, an idle speed control mechanism for controlling the number of revolutions during idling can be reduced, so that the manufacturing cost can be reduced.

  In addition, the specific configuration of each part is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS Schematic structure explanatory drawing explaining the structure of 1st embodiment of this invention. Schematic structure explanatory drawing explaining the structure of 2nd embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Turbocharger 1w ... Waste gate 1a ... Actuator 7 ... Intake passage 8 ... Throttle valve 11 ... VSV
12 ... Supercharging pressure adjustment passage 13b ... Intake bypass passage 13v ... Intake bypass valve 13n ... Intake side control passage

Claims (4)

In an internal combustion engine provided with a supercharger that is provided upstream of a throttle valve provided in an intake passage and supercharges intake air to a combustion chamber, an intake bypass that enables communication between the upstream and downstream of the compressor of the supercharger A passage and an exhaust bypass passage that allows communication between the upstream and downstream of the turbocharger turbine;
The intake bypass passage is provided with an intake bypass valve that opens and closes the intake bypass passage, and the exhaust bypass passage is provided with an exhaust bypass valve that opens and closes the exhaust bypass passage.
Be provided boost pressure adjustment passage with a downstream throttle valve can introduce the supercharging pressure more exhaust bypass valve to open and close the opening regulating valve can introduce atmospheric pressure,
An intake air adjustment system for an internal combustion engine that opens an opening adjustment valve for a predetermined time so that an upstream of a supercharger communicates with a downstream of a throttle valve when the internal combustion engine is started.   2. The intake air adjustment system for an internal combustion engine according to claim 1, wherein when the opening adjustment valve is opened, the idle speed control valve is closed more than the opening at the time of normal starting.   2. The intake air adjustment system for an internal combustion engine according to claim 1, wherein the opening time of the opening adjustment valve is determined in accordance with a duration time during which the internal combustion engine is stopped. In an internal combustion engine provided with a supercharger that is provided upstream of a throttle valve provided in an intake passage and supercharges intake air to a combustion chamber, an intake bypass that enables communication between the upstream and downstream of the compressor of the supercharger A passage,
The intake bypass passage is provided with an intake bypass valve that opens and closes the intake bypass passage.
A supercharging pressure adjusting passage having an opening adjusting valve for adjusting the air amount and communicating with the upstream of the supercharger and the downstream of the throttle valve;
An intake air adjustment system for an internal combustion engine that opens an opening adjustment valve for a predetermined time so that an upstream of a supercharger and a downstream of a throttle valve communicate with each other when the internal combustion engine is started.

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