JP2014238034A - Control device and control method of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To raise a supercharging pressure in starting the operation of an electric supercharger 2 without interference by a bypass valve 16.SOLUTION: An internal combustion engine 1 includes a compressor 5 of a turbo supercharger 3 and an electric supercharger 2 in series in an intake passage 11. The electric supercharger 2 includes a bypass passage 15 and a bypass valve 16 for bypassing the electric supercharger 2 so that the electric supercharger 2 is prevented from becoming ventilation resistance during a non-operation period. When target torque is in a non-supercharge region and the rotating speed is lower than a prescribed rotating speed, the bypass valve 16 is retained at an intermediate opening. Thus, when an accelerator pedal is actuated to transfer the target torque to a supercharging region, the bypass valve 16 is immediately fully closed simultaneously with the start of the operation of the electric supercharger 2, and supercharging pressure is quickly raised.

Description

  The present invention relates to a control device and a control method for an internal combustion engine having an electric supercharger and a bypass passage in an intake passage.

  An internal combustion engine having an electric supercharger in an intake system is known. In Patent Document 1, a bypass passage is provided in parallel with the electric supercharger in order to prevent the electric supercharger from becoming a ventilation resistance when the electric supercharger is not operated, and a bypass valve is provided in the bypass passage. The provided arrangement is disclosed. The bypass valve provided in the bypass passage is driven by, for example, a solenoid, and is configured to open the bypass passage when the electric supercharger is not operated and close the bypass passage when the electric supercharger is operated.

JP 2005-226505 A

  However, in the configuration in which the bypass passage provided in parallel with the electric supercharger as described above is opened and closed by the bypass valve, when the electric supercharger starts to operate in accordance with a change in operating conditions, the bypass valve is quickly If it is not closed, the rise of the supercharging pressure by the electric supercharger will deteriorate. Therefore, high responsiveness is required for the bypass valve, and a large solenoid or the like is required as an actuator.

  The present invention includes an electric supercharger that operates in accordance with a target torque in an intake passage, a bypass passage that bypasses the electric supercharger, and a non-operating state of the electric supercharger in the bypass passage. A control device for an internal combustion engine comprising a bypass valve that opens and closes the bypass passage according to operation, wherein the bypass valve is held at an intermediate opening when the target torque is in a non-supercharging region. It is a feature.

  By maintaining the intermediate opening in the non-supercharging region in this way, the bypass valve can be fully closed immediately when the target torque increases and the electric supercharger starts to operate. The rise of pressure is improved.

  In a preferred aspect, the apparatus has means for calculating an intake air amount necessary for realizing the target torque, and the intermediate opening is variably set according to the intake air amount. That is, when the target torque is in the non-supercharging region, the intermediate opening of the bypass valve is set to the minimum opening within the range that does not limit the intake air amount, and the boost pressure is not increased without increasing the pump loss. Can be maximized in improving

  According to this invention, when the electric supercharger starts to operate with the increase in the target torque, the bypass passage is quickly closed, and the rise of the supercharging pressure is improved. In addition, it is possible to use a relatively small actuator for driving the bypass valve, which is advantageous in reducing driving energy.

BRIEF DESCRIPTION OF THE DRAWINGS Structure explanatory drawing which shows the system structure of one Example of this invention. The flowchart which shows the flow of control of one Example. Explanatory drawing which shows the action | operation area | region etc. of the electric supercharger on the operation area | region which used the target torque and the rotational speed as parameters.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows an internal combustion engine 1 in which an electric supercharger 2 and a turbocharger 3 are used in combination as an embodiment of the present invention. The internal combustion engine 1 is, for example, a 4-stroke cycle spark-ignition gasoline engine, and an exhaust turbine 4 of the turbocharger 3 is disposed in an exhaust passage 6 thereof. A catalytic converter 7 using a three-way catalyst is arranged. An exhaust silencer (not shown) is provided further downstream of the exhaust passage 2, and the exhaust passage 6 is opened to the outside through the exhaust silencer. The exhaust turbine 4 includes a known waste gate valve 8 for supercharging pressure control. The internal combustion engine 1 has, for example, an in-cylinder direct injection type configuration. A fuel injection valve (not shown) that injects fuel into the cylinder is provided for each cylinder, and includes an ignition plug 9. The injection timing and injection amount of the fuel injection valve and the ignition timing of the spark plug 9 are controlled by the engine control unit 10.

  In the intake passage 11 of the internal combustion engine 1, an air cleaner 12, an air flow meter 13, and a throttle valve 14 are arranged in this order from the upstream side, and the compressor 5 of the turbocharger 3 is connected to the air flow meter 13 and the throttle valve. It is arranged between the valve 14. The electric supercharger 2 is disposed between the compressor 5 and the air flow meter 13. That is, the compressor 5 and the electric supercharger 2 of the turbocharger 3 are arranged in series so that the electric supercharger 2 is relatively upstream. A bypass passage 15 is provided so as to connect the inlet side and the outlet side of the electric supercharger 2 without going through the electric supercharger 2. The bypass passage 15 is provided with a bypass valve 16 that opens and closes the bypass passage 15. An intercooler 17 is interposed between the compressor 5 and the throttle valve 14. The throttle valve 14 is located at the inlet of the collector 11a, and the intake passage 11 downstream of the collector 11a is branched as a branch for each cylinder. In the present invention, a configuration in which the electric supercharger 2 is disposed on the downstream side of the compressor 5 of the turbocharger 3 is also possible.

  The throttle valve 14 includes an actuator such as an electric motor, and the engine control is based on a detection signal of an accelerator opening sensor 21 that detects an opening of an accelerator pedal (not shown) operated by a driver. The opening degree is controlled by a control signal from the unit 10. The intake air amount controlled by the throttle valve 14 is detected by the air flow meter 13. The engine control unit 10 receives detection signals from various sensors including a detection signal from the crank angle sensor 22 indicating the engine speed and a detection signal from the air flow meter 13 indicating the intake air amount. ing.

  The electric supercharger 2 includes a compressor unit 2a interposed in the intake passage 11 and an electric motor 2b that drives the compressor unit 2a. In FIG. 1, the compressor section 2a is illustrated as a centrifugal compressor, similarly to the compressor 5 of the turbocharger 3. However, in the present invention, any type of compressor such as a roots blower or a screw compressor is used. Is possible. Similarly, in FIG. 1, the bypass valve 16 is exemplified by a butterfly valve that is opened and closed by a solenoid or an electric motor. However, in the present invention, the bypass valve 16 is not limited to a butterfly valve and may be another type of valve. May be. The electric supercharger 2 and the bypass valve 16 are controlled by the engine control unit 10 as described later.

  Next, FIG. 3 is an explanatory diagram illustrating the operating region of the electric supercharger 2 using the target torque tTe and the rotational speed Ne of the internal combustion engine 1 as parameters. An outline of control of the feeder 2 and the bypass valve 16 will be described.

  In FIG. 3, the broken line T0 indicates the torque (load) at which the supercharging pressure is equivalent to the atmospheric pressure. Accordingly, the operating region above this is the supercharging region, and the lower operating region is the non-supercharging region. It becomes. In the present embodiment, the supercharging region is further divided into three operation regions. That is, as shown in the figure, the supercharging region is located between the first supercharging region A located in the low speed and high load region, the third supercharging region C located in the high speed region where the rotational speed Ne is high, and both. 2nd supercharging area | region B is included.

  Here, a line indicated as “WOT” surrounding the entire operation region indicates the fully open characteristic of the entire internal combustion engine 1 that uses both the electric supercharger 2 and the turbocharger 3. The line indicated by “” indicates the torque that can be realized in the steady state only by the turbocharger 3 without depending on the electric supercharger 2. Thus, the torque that can be obtained in a steady state only with the turbocharger 3 is relatively low in the low-speed rotation region, and becomes the maximum torque at a rotational speed that is sufficient for driving the exhaust turbine 4 so that the displacement is sufficient. The first supercharging region A is set so as to compensate for the torque shortage in the low speed rotation region, and therefore, the first supercharging region A is between the line WOT and the line WOT1 in the low speed rotation region. In the first supercharging region A, the electric supercharger 2 operates and the bypass valve 16 is kept fully closed.

  The third supercharging region C is a region on the relatively high speed side where the turbocharger 3 operates sufficiently, and the target torque tTe can be realized only by the turbocharger 3. Accordingly, in the third supercharging region C, the electric supercharger 2 is not operated. The bypass valve 16 is fully opened so that the electric supercharger 2 does not become a ventilation resistance. On the line of the fully open characteristic WOT, the third supercharging region C and the first supercharging region A are substantially adjacent to each other at a certain rotational speed.

  In the second supercharging region B, the target torque tTe can be realized only by supercharging of the turbocharger 3 in a steady state (that is, included in the region of WOT1), but the turbocharger is in a transient state. This corresponds to an operation region where it is difficult to obtain the target torque tTe due to a response delay of 3. The rotational speed that becomes the boundary between the second supercharging region B and the third supercharging region C substantially coincides with the boundary between the first supercharging region A and the third supercharging region C on the high load side. Yes. On the low load side, the rotational speed Neth on the slightly higher rotation side becomes the boundary between the second supercharging region B and the third supercharging region C. In the second supercharging region B, the electric supercharger 2 operates and the bypass valve 16 is fully closed for a predetermined time after the operating condition shifts to the second supercharging region B. Thereby, the rising of the supercharging pressure by the turbocharger 3 is assisted by the electric supercharger 2 and the acceleration performance is improved. After a predetermined time has elapsed, the electric supercharger 2 is deactivated and the bypass valve 16 is fully opened. By fully opening the bypass valve 16 in this way, the occurrence of pressure loss due to the bypass valve 16 is avoided, and subsequent rise of the supercharging pressure by the turbocharger 3 is not hindered.

  On the other hand, the non-supercharging region where the supercharging pressure is negative is further divided into a first non-supercharging region D on the low speed side and a second non-supercharging region E on the high speed side. These two regions are divided with the rotational speed Neth serving as the boundary between the second supercharging region B and the third supercharging region C as a boundary. This rotational speed Neth corresponds to a rotational speed at which the electric supercharger 2 does not need to be operated even when the accelerator pedal is depressed and the operating condition shifts to the supercharging region when the rotational speed Ne is higher than this.

  In the second non-supercharging region E, the electric supercharger 2 is inactive and the bypass valve 16 is fully opened in order to prevent the electric supercharger 2 from becoming a ventilation resistance. Therefore, the electric supercharger 2 does not impair the responsiveness of the turbocharger 3.

  On the other hand, in the first non-supercharging region D, the electric supercharger 2 is inoperative because it is a non-supercharging region that does not require supercharging, but the bypass valve 16 is not fully opened but is held at an intermediate opening. Is done. More specifically, corresponding to the intake air amount under each operating condition, the minimum opening degree that does not limit the intake air amount is maintained. By maintaining the intermediate opening in this manner, the bypass valve 16 can be fully closed immediately when the target torque tTe shifts to the supercharging region, and the operation of the electric supercharger 2 is started. The boost pressure rises quickly.

  Next, the control of the electric supercharger 2 and the bypass valve 16 of the above embodiment will be described in more detail based on the flowchart of FIG.

  The control routine shown in FIG. 2 is repeatedly executed at predetermined time intervals in the engine control unit 10. In step 1, the control routine is detected by the accelerator opening APO detected by the accelerator opening sensor 21 and the crank angle sensor 22. The engine speed Ne to be read is read.

  In step 2, a target torque (target load) tTe of the internal combustion engine 1 is calculated based on the accelerator opening APO and the rotational speed Ne. Then, in step 3, it is determined whether or not the target operating conditions (target torque tTe, rotational speed Ne) are in the non-supercharging region (see FIG. 3). If YES here, the process proceeds to step 4; if NO, the process proceeds to step 8.

  In step 4, it is determined whether or not the rotational speed Ne is lower than the predetermined rotational speed Neth described above. That is, it is determined whether it is the first non-supercharging region D or the second non-supercharging region E of FIG. If YES, that is, in the first non-supercharging region D, the process proceeds to step 5, and if NO, that is, in the second non-supercharging region E, the process proceeds to step 6.

  In step 5, the bypass valve opening BVO is calculated based on the target torque tTe and the rotational speed Ne. Specifically, since the required intake air amount is determined from the target torque tTe and the rotational speed Ne, the minimum opening at which the bypass valve 16 is not rate-controlled with respect to the intake air amount is defined as the bypass valve opening BVO. The bypass valve 16 is controlled to an intermediate opening according to the bypass valve opening BVO calculated in step 5 by another routine (not shown). Note that the intake air amount detected by the air flow meter 13 when setting the intermediate opening BVO can be used. However, when the intake air amount calculated based on the target torque tTe is used as described above, Therefore, it is possible to maintain an appropriate opening degree.

  By controlling the bypass valve 16 to the intermediate opening in this manner, when the required operating condition shifts from the first non-supercharging region D to the first supercharging region A or the second supercharging region B (for example, 3), the bypass valve 16 can be immediately fully closed at the transition from the D1 point to the A1 point or the transition from the D2 point to the B1 point shown in FIG. 3, and the supercharging pressure by the electric supercharger 2 can be increased. It can be raised quickly.

  In step 6, which is executed when the determination in step 4 is NO, that is, in the second non-supercharging region E, the bypass valve opening BVO is set to fully open. When the rotational speed Ne is equal to or higher than the predetermined rotational speed Neth, even if the accelerator pedal is depressed and the driving condition shifts to the supercharging region (for example, shift from E1 to C1 shown in FIG. 3), Since the supercharging region C is a region where the electric supercharger 2 is not operated, the bypass valve 16 is not closed. Rather, the bypass valve opening BVO is fully opened in advance so as not to hinder the rise of the supercharging pressure by the turbocharger 3.

  In either case of step 5 or step 6, the process proceeds to step 7. In Step 7, since the target operating condition is in the non-supercharging region, the electric supercharger 2 is stopped.

  On the other hand, in step 8 executed when the target operating condition is within the supercharging region, it is further determined whether or not the operating condition is within the first supercharging region A. As described above, the first supercharging region A is an operating region in which the target torque tTe cannot be achieved with the turbocharger 3 alone. Accordingly, if YES is determined in this step, the process proceeds to step 9 so as to set the bypass valve opening BVO to be fully closed, and in step 13, the electric supercharger 2 is operated.

  If the determination in step 8 is NO, it is further determined in step 10 whether or not the target operating condition is within the second supercharging region B. As described above, in the second supercharging region B, the target torque tTe can be realized with only the turbocharger 3 steadily. However, since the rotational speed Ne is relatively low, a delay in rising of the supercharging pressure is caused. (So-called turbo lag) is a problem area. Therefore, the supercharging pressure is assisted by the electric supercharger 2 only at the initial stage when the operating condition has shifted to this region.

  When it is determined in step 10 that it is in the second supercharging region B, the process proceeds to step 11 and a predetermined time (time required for assisting by the electric supercharger 2) after the operating condition shifts to the second supercharging region B. It is determined whether it is within. If it is within the predetermined time, the process proceeds to step 12 where the bypass valve opening BVO is set to be fully closed, and in step 13, the electric supercharger 2 is operated.

  If it is determined in step 11 that a predetermined time has elapsed, the process proceeds to step 14 where the bypass valve opening BVO is set to fully open, and in step 15, the electric supercharger 2 is deactivated. That is, after that, supercharging is performed only by the turbocharger 3.

  On the other hand, if it is determined in step 10 that it is not in the second supercharging region B, the target operating condition is in the third supercharging region C. In this case, since the target torque tTe can be realized only by the turbocharger 3, the process proceeds to step 14, the bypass valve opening BVO is set to fully open, and the electric supercharger 2 is deactivated in step 15. .

  As mentioned above, although one Example of this invention was described in detail, this invention is not limited to the said Example, A various change is possible.

  For example, in the above embodiment, the embodiment in which the electric supercharger 2 and the turbocharger 3 are used together has been described. However, the present invention can be similarly applied to an internal combustion engine having only the electric supercharger. It is. In this case, since the electric supercharger is generally used only on the low speed side, if the opening degree is intermediate in the non-supercharged region on the low speed side and fully opened in the operating condition where the electric supercharger is inactive on the high speed side, Good.

  In the above-described embodiment, the intermediate opening is variably set according to the intake air amount. However, for a simple control, the intermediate opening may be constant.

  Furthermore, the electric supercharger is not limited to one that is simply turned on / off, and may be one whose capacity is variably controlled during operation.

DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine 2 ... Electric supercharger 3 ... Turbocharger 10 ... Engine control unit 15 ... Bypass passage 16 ... Bypass valve

Claims (7)

An electric supercharger that operates in accordance with the target torque is provided in the intake passage, and a bypass passage that bypasses the electric supercharger is provided, and the bypass passage is provided in accordance with non-operation / operation of the electric supercharger. A control device for an internal combustion engine comprising a bypass valve for opening and closing the bypass passage,
A control apparatus for an internal combustion engine, wherein the bypass valve is held at an intermediate opening when the target torque is in a non-supercharging region.   2. The control device for an internal combustion engine according to claim 1, wherein the internal combustion engine further includes a turbocharger, and the compressor of the turbocharger and the electric supercharger are arranged in series. .   3. The control device for an internal combustion engine according to claim 2, wherein the bypass valve is fully opened when the engine speed is not less than a predetermined speed in a non-supercharging region.   4. The control device for an internal combustion engine according to claim 2, wherein an operating region of the electric supercharger is determined from a target torque and an engine speed.   The operating range that can be realized only by supercharging of the turbocharger is included in the operating range. In this region, the electric turbocharger is deactivated and the bypass valve is fully opened after a predetermined time has elapsed. The control apparatus for an internal combustion engine according to claim 4, wherein: Means for calculating an intake air amount necessary to realize the target torque,
6. The control apparatus for an internal combustion engine according to claim 1, wherein the intermediate opening is variably set according to the intake air amount. An electric supercharger that operates in accordance with the target torque is provided in the intake passage, and a bypass passage that bypasses the electric supercharger is provided, and the bypass passage is provided in accordance with non-operation / operation of the electric supercharger. In an internal combustion engine comprising a bypass valve for opening and closing the bypass passage,
A control method for an internal combustion engine, wherein the bypass valve is held at an intermediate opening when the target torque is in a non-supercharging region.

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