JP5264628B2 - Control device for internal combustion engine - Google Patents

Description

  The present invention relates to a control device for an internal combustion engine having a function of controlling driving of an electric supercharger in accordance with a driving state of a vehicle and an intake pipe pressure.

  In a conventional control device for an internal combustion engine, in order to increase the output of the internal combustion engine, the drive of the electric motor of the electric supercharger provided on the intake passage is controlled, and the pressure of the intake air sucked into the cylinder ( In some cases, the intake air pressure is increased to supercharge the intake air. In recent years, an electric supercharger has been used to reduce the engine displacement for the purpose of reducing fuel consumption in addition to the conventional purpose of improving output.

  Here, at the time of high output of the internal combustion engine, when the throttle disposed downstream of the compressor is closed in the compressed state by the compressor of the electric supercharger, the intake pipe pressure is extremely high, that is, It becomes supercharged. This supercharging may damage intake system components.

  On the other hand, in order to reduce the influence of the supercharging of the electric supercharger as described above, the drive of the electric motor is feedback-controlled so as to cope with the case where the throttle is closed. For example, in a conventional control device for an internal combustion engine as shown in Patent Document 1, an electric motor is provided coaxially with a turbine compressor, and the rotational speed of the electric motor having the same rotational speed as that of the turbine compressor is monitored. The drive of the electric motor is feedback controlled based on the rotational speed of the electric motor by utilizing the fact that the rotational speed of the turbine / compressor increases prior to the increase of the intake pipe pressure.

JP 2007-23816 A

  However, in the conventional control device for an internal combustion engine as shown in Patent Document 1, as shown in the conventional example of FIG. 5, the intake pipe pressure rises when the throttle valve is fully closed. Then, after the throttle valve is fully closed, a mechanical delay time (arrow X) is left, and then the motor rotation speed increases due to the influence of the increase in the intake pipe pressure. Thereafter, when the motor rotation speed reaches a predetermined pressure reduction control start value (arrow Y), the pressure reduction control is started and the intake pipe pressure is reduced. Thus, in the conventional control device for an internal combustion engine as shown in Patent Document 1, a relatively large delay as shown in FIG. 5 occurs.

  Therefore, in the control apparatus for a conventional internal combustion engine as shown in Patent Document 1, since the feedback control is based on the rotation speed of the electric motor, until the feedback control action occurs as indicated by an arrow Z in FIG. An increase in intake pipe pressure is inevitable. For this reason, even in a conventional control device for an internal combustion engine as shown in Patent Document 1, intake system components such as a compressor, a throttle valve, and an intake pipe may be damaged by supercharging.

  Further, in order to suppress such supercharging, it is necessary to provide a blow-off valve on the intake side of the internal combustion engine for releasing the air between the compressor and the throttle to the atmosphere or circulating the air upstream of the intake air. For this reason, in the conventional one, the number of parts has increased.

  The present invention has been made to solve the above-described problems, and can reduce the intake pipe pressure at an early stage, and can generate supercharging even when the blow-off valve is not used. An object of the present invention is to obtain a control device for an internal combustion engine that can suppress the above-mentioned problem.

  A control device for an internal combustion engine according to the present invention is provided rotatably in an intake passage of the internal combustion engine, and supercharges intake air of the internal combustion engine by rotating, and an electric motor that drives rotation of the compressor wheel. An intake pipe pressure detecting means for generating a signal corresponding to the intake pipe pressure, and a signal corresponding to the throttle opening of the throttle valve provided in the intake passage. A throttle opening detection means to be generated; and an electric motor control unit that monitors the intake pipe pressure and the throttle opening through the intake pipe pressure detection means and the throttle opening detection means and controls the driving of the electric motor. The motor control unit calculates a displacement amount per unit time of the throttle valve based on the monitored throttle opening, and calculates When a displacement in the closing direction of the throttle valve is detected from the displacement amount, an intake pipe that is an estimated value of the intake pipe pressure after a predetermined time based on the intake pipe pressure and the displacement amount at that time When a pressure increase estimated value is calculated and it is confirmed that the calculated intake pipe pressure increase estimated value exceeds a predetermined threshold value, it is determined that supercharging occurs, and the drive of the electric motor is controlled by the intake pipe. It controls to the pressure reduction side.

  According to the control device for an internal combustion engine according to the present invention, when the motor control unit detects the displacement in the closing direction of the throttle valve from the displacement amount of the throttle valve per unit time, the intake pipe pressure and the displacement amount are calculated. Based on the above, the estimated intake pipe pressure rise is calculated, and when it is confirmed that the estimated intake pipe pressure rise exceeds the predetermined threshold, it is determined that supercharging occurs, and the drive of the motor is Since the pipe pressure is controlled to the pressure reduction side, feedback pipe control to the pressure reduction side of the intake pipe pressure is triggered by the displacement of the throttle valve in the closing direction. An effect can be produced, and the occurrence of supercharging can be suppressed even when the blow-off valve is not used.

1 is a configuration diagram showing an internal combustion engine according to Embodiment 1 of the present invention. FIG. It is a flowchart which shows operation | movement of the electric motor control apparatus of FIG. It is explanatory drawing for demonstrating an operating condition. It is explanatory drawing for demonstrating the operation timing of the electric motor control apparatus of FIG. It is explanatory drawing for demonstrating the operation timing of the control apparatus of the conventional internal combustion engine.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.
Embodiment 1 FIG.
1 is a block diagram showing an internal combustion engine according to Embodiment 1 of the present invention.
In FIG. 1, an internal combustion engine 1 is a four-cylinder gasoline engine and has a cylinder block 2 having four cylinders. Further, the internal combustion engine 1 is configured to achieve high output and low fuel consumption by supercharging intake air into each cylinder by the electric supercharger 10.

  An intake manifold 3 is connected to the suction port of each cylinder. An exhaust manifold 4 is connected to the discharge port of each cylinder. An intake pipe is connected to the side of the intake manifold 3 opposite to the cylinder, and an intake passage 5 is formed by the intake pipe and the intake manifold 3. An exhaust pipe is connected to the non-cylinder side of the exhaust manifold 4, and an exhaust passage 6 is formed by the exhaust pipe and the exhaust manifold 4.

  An electric supercharger 10 is provided between the intake passage 5 and the exhaust passage 6. The electric supercharger 10 includes a turbine wheel 11, a rotating shaft 12, a compressor wheel 13 and an electric motor 14. The turbine wheel 11 and the compressor wheel 13 are attached to one end and the other end of the rotating shaft 12, respectively. That is, the turbine wheel 11 and the compressor wheel 13 are arranged coaxially with each other.

  The turbine wheel 11 receives exhaust gas generated in each cylinder of the cylinder block 2 and rotates. The turbine wheel 11 has a turbine variable vane 11a for adjusting the transmission efficiency of exhaust energy. The compressor wheel 13 rotates together with the turbine wheel 11. Moreover, the compressor wheel 13 compresses intake air by rotating. Furthermore, the compressor wheel 13 has a compressor variable vane 13a for adjusting the amount of compressed air.

  The electric motor 14 drives the rotary shaft 12 to rotate. The electric motor 14 is provided with a rotational speed detection means (not shown) that generates a signal corresponding to the rotational speed of the rotary shaft 12. Further, when the electric motor 14 rotates the rotary shaft 12 and the compressor wheel 13 in the forward direction (one of the circumferential directions of the rotary shaft 12), the electric motor 14 pressurizes the intake pipe pressure of the intake passage 5 and is sucked into the cylinder. Supercharge intake air. At the same time, the electric motor 14 reduces the intake pipe pressure when the rotary shaft 12 and the compressor wheel 13 are rotationally driven in the reverse direction (the other in the circumferential direction of the rotary shaft 12).

  The basic operation of the electric supercharger 10 is that when the internal combustion engine 1 is rotating at low speed, the intake air is supercharged by the rotational drive of the electric motor 14, and at the time of high rotation of the internal combustion engine 1, The intake air is supercharged by rotation. However, the operation of the electric supercharger 10 is not limited to this example. Even if the supercharging due to the rotational drive of the electric motor 14 and the supercharging due to the exhaust energy are superimposed regardless of the rotational speed of the internal combustion engine 1. Good.

  In addition, an air flow sensor 20 (intake amount detection means) that generates a signal corresponding to the intake air amount is provided on the intake passage 5 upstream of the electric supercharger 10 (on the side of the anti-internal combustion engine 1). Further, an intake pipe pressure sensor 21 (intake pipe pressure detecting means) for generating a signal corresponding to the intake pipe pressure on the downstream side of the electric supercharger 10 is provided on the downstream side of the electric supercharger 10 in the intake passage 5. It has been.

  An intercooler 22 that cools the intake air is provided on the intake passage 5 downstream of the intake pipe pressure sensor 21. Further, a throttle valve 23 for adjusting the flow rate of the intake air flowing through the intake passage 5 is provided on the downstream side of the intercooler 22 in the intake passage 5. A throttle valve actuator 24 that opens and closes the throttle valve 23 is connected to the throttle valve 23.

  The throttle valve actuator 24 generates a signal corresponding to the opening degree of the throttle valve 23. Further, the throttle valve actuator 24 has a built-in throttle opening detecting means (not shown), and the throttle opening detecting means generates a signal corresponding to the opening of the throttle valve 23.

  Here, the exhaust passage 6 branches into a turbine side passage 6 a that guides exhaust gas to the turbine wheel 11 and a bypass passage 6 b that bypasses the turbine wheel 11. A waste gate valve 30 that opens and closes an opening to the bypass passage 6b and a waste gate valve actuator 31 that opens and closes the waste gate valve 30 are attached to a branch point in the exhaust passage 6.

  Next, a flow until the intake air taken into the intake passage 5 of the internal combustion engine 1 is discharged from the exhaust passage 6 will be described. First, dust is removed from the intake air taken into the intake passage 5 from the atmosphere by an air cleaner (not shown). Subsequently, the intake air from which the dust has been removed passes through the air flow sensor 20 and is compressed by the rotation of the compressor wheel 13 of the electric supercharger 10.

  Next, the compressed intake air expands due to an increase in temperature due to an increase in pressure. Therefore, the compressed intake air is cooled by the intercooler 22 in order to improve the intake charge efficiency of the internal combustion engine 1. Subsequently, the flow rate of the cooled intake air is adjusted according to the opening degree of the throttle valve 23. In the case of a port injection engine, it is mixed with fuel to form an air-fuel mixture, and is sucked into each cylinder of the cylinder block 2.

  Thereafter, the air-fuel mixture sucked into the cylinder is ignited, and a piston (not shown) in the cylinder is pushed down. Subsequently, the vertical motion of the piston is converted into a rotational motion by a crank (not shown), and the energy generated by the combustion of the air-fuel mixture is used as motive power as the driving force of the vehicle.

  Further, exhaust gas generated by combustion in the cylinder is exhausted from the cylinder through the exhaust manifold 4. Subsequently, when the wastegate valve 30 is closed, the exhaust gas discharged from the cylinder is guided to the turbine wheel 11 through the turbine side passage 6a to rotate the turbine wheel 11.

  On the other hand, the exhaust gas is guided to the bypass passage 6b when the wastegate valve 30 is open. Then, the exhaust gas that has rotated the turbine wheel 11 and the exhaust gas that has passed through the bypass passage 6b merge, and are purified by a muffler (not shown) integrated with an exhaust gas purification catalyst or the like, and discharged into the atmosphere. The

  Next, the control system of the internal combustion engine 1 and the electric supercharger 10 will be described. An electric motor control device 40 (electric motor control unit) is connected to the electric motor 14 of the electric supercharger 10. An engine control device 41 is connected to the motor control device 40. The electric motor control device 40 and the engine control device 41 are hardware (arithmetic logic operable circuits) each having a CPU, a RAM, a ROM, and the like.

  Further, the engine control device 41 monitors the motor rotation speed, the intake air amount, and the intake pipe pressure via the electric motor 14, the airflow sensor 20, and the intake pipe pressure sensor 21, respectively. Further, the engine control device 41 includes a throttle opening signal from the throttle valve actuator 24, a waste gate valve opening signal from the waste gate valve actuator 31, a turbine variable vane opening signal from the turbine variable vane 11a, And a compressor variable vane opening signal from the compressor variable vane 13a.

  The engine control device 41 controls the driving of the turbine variable vane 11a, the compressor variable vane 13a, the throttle valve actuator 24, and the wastegate valve actuator 31. Further, the engine control device 41 sends information on the throttle opening and the intake pipe pressure to the motor control device 40.

  Further, the motor control device 40 calculates an intake pipe pressure increase estimated value (intake pipe pressure increase predicted value) based on information on the throttle opening and the intake pipe pressure from the engine control apparatus 41, and feedback controls the motor 14. To do. Specifically, the electric motor control device 40 calculates a time differential value of the detected throttle opening. That is, the motor control device 40 calculates the displacement amount of the throttle valve 23 per unit time.

  When the motor control device 40 confirms that the time differential value of the throttle opening is a negative value (when the throttle moves in the closing direction), the current intake pipe pressure and the unit of the throttle valve 23 are determined. Based on the amount of displacement per time, an intake pipe pressure increase estimated value that is an estimated value of the intake pipe pressure after a predetermined time from the present is calculated. When it is confirmed that the calculated intake pipe pressure increase estimated value exceeds a predetermined threshold, the electric motor control device 40 determines that supercharging occurs, and the intake pipe pressure increase estimated value exceeds the predetermined threshold. Intake pipe pressure reduction control is performed according to the value (difference) that has been exceeded.

  Here, the decompression control of the intake pipe pressure is rotation control of the electric motor 14, opening control of the waste gate valve 30, opening control of the turbine variable vane 11a, and opening control of the compressor variable vane 13a. Specifically, the motor control device 40 causes the motor 14 to brake the rotation of the turbine compressor when performing pressure reduction control. At the same time, the motor control device 40 increases the opening degree of the wastegate valve 30 (based on the respective states at the time when it is determined that supercharging occurs) via the engine control device 41, and the turbine variable vane 11a. And the opening degree of the compressor variable vane 13a is decreased.

  When the motor 14 is caused to brake the rotation of the turbine compressor, the motor 14 may be driven and controlled in the direction opposite to the supercharging direction, or the motor 14 may be regeneratively controlled. In other words, the drive of the motor 14 is controlled to the pressure reducing side of the intake pipe pressure by performing drive control or regenerative control of the motor 14 in the reverse direction. In this case, more effective braking control is possible when the drive control is performed in the reverse direction than when the regenerative control is performed.

  Next, an example of the operation of the motor control device 40 will be described. FIG. 2 is a flowchart showing an example of the operation of the motor control device 40 of FIG. In FIG. 2, first, the motor control device 40 acquires vehicle parameters from the engine control device 41 (step S1). Specifically, the motor control device 40 acquires information on the motor speed, the opening degree of the throttle valve 23, the intake air amount, and the intake pipe pressure from the engine control device 41.

  In step S2, the motor control device 40 calculates a time differential value of the throttle opening, and determines whether the time differential value is positive or negative. Here, the time differential value of the throttle opening is synonymous with the rotational direction of the throttle valve 23. When the time differential value is positive, it means that the throttle valve 23 has moved in the opening direction. Is negative, it means that the throttle valve 23 has moved in the closing direction.

  In step S2, when it is confirmed that the time differential value of the throttle opening is positive (that is, in the NO direction), the motor control device 40 ends the operation of FIG. On the other hand, in step 2, when it is confirmed that the time differential value of the throttle opening is negative (that is, in the YES direction), the motor control device 40 calculates the intake pipe pressure increase estimated value (step S3). .

  Here, the estimated value of the intake pipe pressure rise is a sum value of the intake pipe pressure rise difference value calculated from the current intake pipe pressure and the time differential value of the throttle opening. This intake pipe pressure increase difference value can be calculated based on the current intake pipe pressure, but in order to improve estimation accuracy, at least one of the motor rotation speed and the intake air amount may be used together with the intake pipe pressure. Good. FIG. 3 shows an example of intake pipe pressure rise estimation. FIG. 3 shows that the magnitude of the intake pipe pressure increase difference value can be determined by the magnitudes of the intake pipe pressure, the time differential value (the absolute value thereof) of the throttle opening, the motor rotation speed, and the intake air amount.

  Subsequently, the motor control device 40 determines whether or not there is a possibility of falling into a supercharged state based on the estimated intake pipe pressure increase estimated value (step S4). At this time, if the motor control device 40 confirms that the estimated intake pipe pressure increase value is smaller than the predetermined threshold value (that is, the NO direction in step S4), there is no possibility of entering a supercharging state. And the operation shown in FIG.

  On the other hand, in step S4, when the motor control device 40 confirms that the estimated intake pipe pressure increase is larger than the predetermined threshold (that is, the YES direction in step S4), the motor control device 40 may fall into a supercharged state. The process proceeds to step S5 to perform braking control (pressure reduction control) of the electric motor 14.

  Here, the braking force of the electric motor 14 corresponds to the differential pressure between the intake pipe pressure increase estimated value and a predetermined threshold value. This braking force is obtained by reverse drive control of the electric motor 14 or by regenerative control of the electric motor 14. When the differential pressure between the intake pipe pressure increase estimated value and the predetermined threshold is larger than the braking force obtained by the regenerative control, the braking force is obtained by reverse driving of the motor 14.

  Therefore, the motor control device 40 predicts whether or not supercharging occurs from the amount of change per unit time (minute time) of the throttle valve 23 using the time differential value of the throttle opening, When the occurrence of supply is predicted, drive control is performed in the pressure reducing direction.

  According to the control device for the internal combustion engine of the first embodiment as described above, when the motor control device 40 detects the displacement of the throttle valve 23 in the closing direction from the amount of displacement of the throttle valve 23 per unit time. Based on the intake pipe pressure and the displacement amount, an estimated intake pipe pressure rise is calculated. When it is confirmed that the intake pipe pressure increase estimated value exceeds a predetermined threshold, the motor control device 40 determines that supercharging occurs, and drives the motor 14 to reduce the intake pipe pressure. To control. With this configuration, when the throttle valve 23 is displaced in the closing direction, feedback control of the intake pipe pressure to the pressure reduction side is started, thereby causing the intake pipe pressure to be reduced earlier than the conventional one. Even when the blow-off valve is not used, the occurrence of supercharging can be suppressed.

  Here, FIG. 4 is an explanatory diagram for explaining the operation timing of the motor control device 40 of FIG. As shown in FIG. 4, the motor control device 40 starts feedback control (braking control) of the motor 14 at the time indicated by the arrow A. Therefore, the time required for estimating the increase in the intake pipe pressure in the motor control device 40 That is, it can be seen that the delay (arrow B) until it is determined that supercharging occurs is shorter than the conventional example of FIG. As a result, in the motor control device 40, as shown by an arrow C in FIG. 4, an increase in the intake pipe pressure is suppressed as compared with the conventional example in FIG.

  In the first embodiment, the electric supercharger 10 is provided between the intake passage 5 and the exhaust passage 6, and the turbine wheel 11 and the compressor wheel 13 are connected to each other by the rotating shaft 12. However, the present invention is not limited to this example. The electric supercharger 10 is a so-called electric compressor that has a compressor wheel 13 and an electric motor 14 provided in the intake passage 5 and supercharges intake air only by electric energy. May be. Thus, even when the turbine wheel 11 of the first embodiment is omitted, the same effect as that of the first embodiment can be obtained.

  In addition to the electric supercharger 10, a so-called twin charger may be configured by further providing a mechanical supercharger at the rear stage or the front stage of the electric supercharger 10 in the intake passage 5 and the exhaust passage 6. Even in this case, the same effect as in the first embodiment can be obtained.

  Furthermore, in the first embodiment, the motor control device 40 and the engine control device 41 are each configured by different hardware. However, the present invention is not limited to this example. For example, when the functions can be integrated into the engine control device 41 or the like, the motor control device 40 may function as a simple driver (drive power generation means) that drives the motor 14. Good. Also in this case, the same effect as in the first embodiment can be obtained.

  In the first embodiment, the turbine wheel 11 has the turbine variable vane 11a, and the compressor wheel 13 has the compressor variable vane 13a. However, these turbine variable vane 11a and compressor variable vane 13a may be omitted.

  Further, in the first embodiment, a 4-cylinder gasoline engine has been described. However, the present invention can also be applied to an internal combustion engine having a number of cylinders and a fuel type other than a 4-cylinder gasoline engine. Further, there is no limitation on the combustion system of the internal combustion engine to which the present invention is applied, and the present invention can be applied to a direct injection engine that directly injects fuel into a cylinder, and an intake on the downstream side of the throttle valve 23. The present invention can also be applied to a port injection engine that injects fuel into the manifold 3.

  DESCRIPTION OF SYMBOLS 1 Internal combustion engine, 5 Intake passage, 10 Electric supercharger, 11 Turbine wheel, 11a Turbine variable vane, 12 Rotating shaft, 13 Compressor wheel, 13a Compressor variable vane, 14 Electric motor, 20 Air flow sensor (intake amount detection means), 21 Intake pipe pressure sensor, 24 Throttle valve actuator, 30 Wastegate valve, 31 Wastegate valve actuator, 40 Motor control device (motor control unit), 41 Engine control device.

Claims (7)

A compressor wheel which is rotatably provided in an intake passage of the internal combustion engine and supercharges intake air of the internal combustion engine by rotating;
A control device for an internal combustion engine connected to an electric supercharger comprising: an electric motor that drives rotation of the compressor wheel;
An intake pipe pressure detecting means for generating a signal corresponding to the intake pipe pressure;
Throttle opening detection means for generating a signal corresponding to the throttle opening of a throttle valve provided in the intake passage;
An electric motor control unit that monitors the intake pipe pressure and the throttle opening degree via the intake pipe pressure detection unit and the throttle opening degree detection unit, and controls driving of the electric motor;
The motor controller is
Based on the throttle opening being monitored, the displacement amount per unit time of the throttle valve is calculated,
When a displacement in the closing direction of the throttle valve is detected from the calculated displacement amount, an estimated value of the intake pipe pressure after a predetermined time based on the intake pipe pressure and the displacement amount at that time. Calculate the estimated intake pipe pressure rise,
When it is confirmed that the calculated estimated intake pipe pressure rise exceeds a predetermined threshold value, it is determined that supercharging occurs, and the drive of the electric motor is controlled to the pressure reducing side of the intake pipe pressure. A control device for an internal combustion engine. A rotational speed detection means for generating a signal according to the rotational speed of the electric motor;
And at least one of intake air amount detecting means for generating a signal corresponding to the intake air amount in the intake passage,
When calculating the intake pipe pressure increase estimated value, the electric motor control unit uses at least one of the intake air amount in the intake passage and the rotation speed of the electric motor together with the intake pipe pressure and the displacement amount. The control apparatus for an internal combustion engine according to claim 1. The motor control unit generates a braking torque for the rotation of the compressor by driving the motor in a direction opposite to a supercharging direction when controlling the driving of the motor to the pressure reducing side of the intake pipe pressure. The control device for an internal combustion engine according to claim 1 or 2, characterized by: The electric motor control unit generates a braking torque for the rotation of the compressor from the electric motor by setting the electric motor to a regenerative state when controlling the driving of the electric motor to the pressure reduction side of the intake pipe pressure. The control apparatus for an internal combustion engine according to claim 1 or 2. The electric supercharger further includes a turbine wheel that is provided in an exhaust passage of the internal combustion engine and rotates together with the compressor wheel,
The exhaust passage of the internal combustion engine is branched into a turbine side passage that passes through the compressor wheel and a bypass passage that bypasses the compressor wheel,
When the motor control unit controls the opening degree of a wastegate valve provided at a branch point between the turbine side passage and the bypass passage and opens and closes the opening to the bypass passage, and determines that supercharging occurs. The control device for an internal combustion engine according to any one of claims 1 to 4, wherein the opening degree of the waste gate valve is increased from a state at the time when it is determined that supercharging occurs. . The turbine wheel has a turbine variable vane for adjusting the transmission efficiency of exhaust energy,
When the motor control unit controls opening and closing of the turbine variable vane and confirms that the intake pipe pressure increase estimated value exceeds the predetermined threshold, when determining that supercharging occurs, The control device for an internal combustion engine according to claim 5, wherein the opening of the turbine variable vane is reduced from a state at the time when it is determined that supercharging occurs. The compressor has a compressor variable vane for adjusting the amount of compressed air,
The motor control unit controls opening and closing of the compressor variable vane, and when it is determined that supercharging occurs, the opening of the compressor variable vane is decreased from a state at the time when it is determined that supercharging occurs The control device for an internal combustion engine according to any one of claims 1 to 6, wherein the control device is an internal combustion engine.

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