JP2005171896A - Control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device for an internal combustion engine capable of realizing good supercharging performance and prevention of degradation of fuel economy performance by suppressing increase of exhaust resistance increase at a time of start of supercharging by motor drive in a turbocharger with a motor. <P>SOLUTION: This control device for the internal combustion engine controls the internal combustion engine 1 provided with the turbocharger 11 and is provided with a motor 11a capable of driving and rotating a compressor wheel and generating power by rotation of a turbine wheel by exhaust gas flow, a bypass passage 27 provided on an exhaust passage 8 for bypassing a turbine wheel, an open close means 28 releasing/shutting off the bypass passage 27, and a control means 16 controlling the motor 11a and the open close means 28. The control means 16 release the bypass passage 27 by the open close means 28 until supercharging pressure rises right after the motor 11a starts driving. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a control device for an internal combustion engine including a supercharger driven by an electric motor on an intake passage.

Attempts to obtain a high output (or low fuel consumption) by supercharging by the supercharger by arranging a supercharger driven by an electric motor on the intake passage of the engine (internal combustion engine) have been used regularly. Yes. [Patent Document 1] also describes a similar internal combustion engine. The supercharger in the internal combustion engine described in [Patent Document 1] is a turbocharger that performs supercharging using exhaust energy, and not only boosts the supercharging effect by supercharging the motor but also reduces the exhaust flow. It is also possible to recover energy by performing regenerative power generation using an electric motor. During regenerative power generation, the motor functions as a generator.
JP-A-5-149143

  In the internal combustion engine described in [Patent Document 1], a bypass path for bypassing the turbine of the turbocharger is also provided, and the turbine of the turbocharger can be bypassed in the exhaust flow. The bypass path opening / closing control is performed by a valve provided in the bypass path. In the internal combustion engine described in [Patent Document 1], the above-described valve opening / closing control is performed for the purpose of improving the regeneration efficiency during engine braking (when the accelerator is not depressed). That is, when the accelerator is off, the exhaust flow is introduced into the turbine of the turbocharger to perform regenerative power generation, so the exhaust flow does not bypass the turbine of the turbocharger (the waste gate valve is also closed). For this reason, if turbo lag occurs when the accelerator pedal is depressed from the accelerator-off state and turbocharging is started, the turbine may become exhaust resistance and adversely affect fuel efficiency.

  Accordingly, an object of the present invention is to suppress an increase in exhaust resistance at the start of supercharging by driving an electric motor in a turbocharger with an electric motor, and to realize good supercharging performance and suppression of deterioration of fuel consumption performance. An object of the present invention is to provide a control device for an internal combustion engine.

  The control apparatus for an internal combustion engine according to claim 1 controls an internal combustion engine including a turbocharger in which a compressor wheel is disposed on an intake passage and a turbine wheel is disposed on an exhaust passage. An electric motor that can be driven to rotate, and that can generate electricity by rotating the turbine wheel by an exhaust flow; a bypass path provided to the exhaust passage so as to bypass the turbine wheel; and an opening / closing means that opens and closes the bypass path; Control means for controlling the electric motor and the opening / closing means, and the control means opens the bypass path by the opening / closing means until the boost pressure rises after the start of driving of the electric motor.

  According to a second aspect of the present invention, in the control apparatus for an internal combustion engine according to the first aspect, the control means shuts off the bypass path by the opening / closing means when the supercharging pressure rises after the start of driving of the electric motor. .

  The invention according to claim 3 further includes a rotational speed detection means for detecting the rotational speed of the electric motor, and based on the rotational speed of the electric motor detected by the rotational speed detection means, whether the boost pressure of the motor has risen. It is characterized by judging whether or not.

  The invention described in claim 4 further includes actual boost pressure detecting means for detecting the actual boost pressure of the internal combustion engine, and the electric motor is based on the actual boost pressure detected by the actual boost pressure detecting means. It is characterized by determining whether or not the supercharging pressure of the engine has risen.

  In the control apparatus for an internal combustion engine according to the first aspect, the bypass path is opened until the actual supercharging is reliably started after the start of driving of the electric motor. For this reason, the exhaust flow bypasses the turbine wheel until the actual supercharging pressure rises after the start of driving of the electric motor, so that the exhaust resistance does not increase and the fuel efficiency does not deteriorate. On the other hand, supercharging is promoted by driving the electric motor. As a result, it is possible to realize good supercharging performance and suppression of deterioration of fuel consumption performance.

  According to the second aspect of the present invention, after the boost pressure rises, the bypass passage is cut off and the turbine wheel is rotated by the exhaust flow. As a result, good supercharging performance can be obtained with the exhaust energy and the electric motor. Further, the backflow of the exhaust flow can be prevented. Note that the rotation drive of the electric motor may be stopped when the supercharging pressure rises. In this case, since the supercharging pressure has already risen, it is possible to perform supercharging with only the exhaust flow with high energy efficiency without consuming electric energy. In addition, when regenerative power generation is possible with an electric motor using the exhaust flow, further improvement in energy efficiency can be realized by performing regenerative power generation when the boost pressure rises.

  An embodiment of the control device of the present invention will be described below. An engine 1 having a control device of the present embodiment is shown in FIG. The engine 1 described in the present embodiment is a multi-cylinder engine, but only one cylinder is shown in FIG. 1 as a sectional view.

  In the engine 1, outside air is taken in as intake air through the intake passage 2, and this intake air is mixed with fuel injected from the injector 4 immediately before the cylinder 3 to form an air-fuel mixture. The air-fuel mixture is sucked into the cylinder 3, compressed by the piston 5, ignited by the spark plug 6, and burned. At this time, the pressure in the cylinder rises due to combustion, and this is taken out as an output via the piston 5 and the connecting rod. An intake valve 7 opens and closes the inside of the cylinder 3 and the intake passage 2. The exhaust gas after combustion is exhausted to the exhaust passage 8. An exhaust valve 9 opens and closes the inside of the cylinder 3 and the exhaust passage 8. On the intake passage 2, an air cleaner 10, an air flow meter 20, a turbocharger 11, an intercooler 12, a throttle valve 13 and the like are arranged from the upstream side.

  The air cleaner 10 is a filter that removes dust and dirt in the intake air. The air flow meter 20 of the present embodiment is of a hot wire type and detects an intake air amount as a mass flow rate. The turbocharger 11 is disposed between the intake passage 2 and the exhaust passage 8 and performs supercharging. In the turbocharger 11 of this embodiment, the compressor wheel and the turbine wheel are connected by a rotating shaft (hereinafter, this portion is simply referred to as a turbine / compressor). Further, the turbocharger 11 of this embodiment incorporates a turbo motor (electric motor) 11a so that the rotating shaft of the turbine / compressor serves as an output shaft. It is possible to assist supercharging by driving the turbo motor 11a.

  The turbo motor 11a can also function as a generator that generates power using exhaust energy, and is sometimes called a motor generator because it has the functions of a motor and a generator. The turbocharger 11 can also function as a normal turbocharger that performs supercharging only with exhaust energy without being assisted by the turbomotor 11a. The turbo motor 11a has a rotor fixed to the rotating shaft of the turbine / compressor and a stator disposed around the rotor as main components.

  On the downstream side of the turbocharger 11 on the intake passage 2, an air-cooled intercooler 12 is disposed that lowers the temperature of the intake air whose temperature has increased as the pressure has increased due to supercharging by the turbocharger 11. The temperature of the intake air is lowered by the intercooler 12 to improve the filling efficiency. A throttle valve 13 that adjusts the amount of intake air is disposed downstream of the intercooler 12.

  The throttle valve 13 of the present embodiment is a so-called electronically controlled throttle valve, and an operation amount (accelerator opening degree TA) of the accelerator pedal 14 is detected by an accelerator position sensor 15, and this detection result and other information amounts are used. Then, the opening degree of the throttle valve 13 is determined by an electronic control unit (ECU: control means) 16 described later. The throttle valve 13 is opened and closed by a throttle motor 17 that is provided in association therewith. Further, a throttle positioning sensor 18 that detects the opening degree of the throttle valve 13 is also provided. In the surge tank on the downstream side of the throttle valve 13, a pressure sensor (actual supercharging pressure detecting means) 19 for detecting the pressure (supercharging pressure / intake pressure) in the intake passage 2 is disposed.

  On the other hand, an exhaust purification catalyst 23 for purifying exhaust gas is attached on the exhaust passage 8 downstream of the turbocharger 11. A crank positioning sensor 26 that detects the rotational position of the crankshaft is attached in the vicinity of the crankshaft of the engine 1. The crank positioning sensor 26 can also detect the engine speed Ne from a change in the position of the crank position. The sensors / actuators described above are connected to the ECU 16, and the detection result is sent to the ECU 16 or controlled by a signal from the ECU 16. The ECU 16 is an electronic control unit that includes a CPU, a ROM, a RAM, and the like.

  The ECU 16 is also connected to the above-described controller 21 of the turbo motor 11a, and the ECU 16 and the controller 21 emphasize and control the turbo motor 11a. The controller 21 can also detect the rotation speed of the turbo motor 11a. The controller 21 is also connected to a battery 22 that stores electrical energy supplied to the turbo motor 11a. The battery 22 is also connected to the ECU 16, and its voltage is monitored by the ECU 16. As described above, regenerative power generation by the turbo motor 11 a is possible, and the electric power generated in the turbo motor 11 a is stored in the battery 22 via the controller 21.

  An intake side bypass passage 24 is provided so as to bypass the upstream side and the downstream side of the compressor wheel on the intake side of the turbocharger 11 described above. On the intake side bypass path 24, a valve 25 for adjusting the amount of intake air passing through the intake side bypass path 24 is disposed. The flow rate of the valve 25 of this embodiment can be adjusted by DUTY control, and can be maintained in a fully open state or a fully closed state. The opening degree (open / close DUTY ratio) of the valve 25 is electrically controlled based on a signal from the ECU 16, and the flow rate of air passing through the intake side bypass path 24 can be arbitrarily adjusted. When the valve 25 is fully opened, if the compressor wheel has an intake resistance, the intake air flows downstream through the intake side bypass passage 24 having no (or less) intake resistance, and the compressor wheel is Bypass.

  On the other hand, an exhaust side bypass passage 27 is provided so as to bypass the upstream side and the downstream side of the turbine wheel on the exhaust side of the turbocharger 11 described above. A valve (opening / closing means) 28 for adjusting the amount of exhaust gas passing through the exhaust side bypass passage 27 is disposed on the exhaust side bypass passage 27. Similarly to the valve 25 described above, the flow rate of the valve 28 can be adjusted by DUTY control, and the valve 28 can be maintained in a fully open state or a fully closed state. The opening degree of the valve 28 is also electrically controlled based on a signal from the ECU 16, and the amount of exhaust gas passing through the exhaust side bypass passage 27 can be arbitrarily adjusted. When the valve 28 is fully opened, if the turbine wheel has an intake resistance, the exhaust gas flows downstream through the exhaust-side bypass path 27 having no intake resistance (or less) and bypasses the turbine wheel.

  Next, the supercharging control by the control device described above will be described. The supercharging control flowcharts are shown in FIGS. The control of the flowcharts shown in FIGS. 2 to 4 is repeatedly executed. The present invention has a feature in bypassing the exhaust flow by the exhaust side bypass passage 27. In the following description, the above-described opening / closing control of the intake side bypass passage 24 is not mentioned.

  First, the engine speed Ne is detected by the crank positioning sensor 26, and the accelerator opening degree TA is detected by the accelerator position sensor 15 (step 200). Next, based on the detected engine speed Ne and accelerator opening degree TA, a target boost pressure Tp is determined from a map created in advance by experiments or the like and stored in the ROM of the ECU 16 (step 205). An example of the map used at this time is shown in FIG. The map of FIG. 5 shows a plurality of target boost pressure Tp curves on a two-dimensional coordinate axis composed of the engine speed Ne and the accelerator opening degree TA. The target boost pressure Tp is determined based on the target boost pressure Tp curve at the coordinate position obtained from the detected engine speed Ne and the accelerator opening degree TA. The map for obtaining the target boost pressure Tp may be a three-dimensional or higher map including other parameters.

  When the target boost pressure Tp is determined, the actual boost pressure Rp is detected by the pressure sensor 19 (step 210). Here, the actual supercharging pressure Rp is measured by the surge tank on the intake passage 2, but may be measured by the intake manifold section. Next, the difference Ep = Tp−Rp is calculated from the target boost pressure Tp and the actual boost pressure Rp (step 215). When the difference Ep is calculated, it is determined whether or not the difference Ep is a negative value (step 220). If step 220 is negative, that is, if the difference Ep is a positive value (or zero) and the actual supercharging pressure Rp is smaller than the target supercharging pressure Tp, supercharging by the turbo motor 11a is necessary. Therefore, as shown in FIG. 3, first, an energization addition amount α to the turbo motor 11a is calculated (step 225). This energization addition amount α is obtained as a function f (Ep) of the difference Ep. Then, the calculated addition amount α is added to the current motor energization amount Im, and this is set as a new motor energization amount Im (step 230).

  When the driving is started from the state where the turbo motor 11a is not driven, the current motor energization amount Im is zero, so the energization addition amount α calculated in step 225 becomes the motor energization amount Im as it is. When the driving of the turbo motor 11a has already been started, a new Im is calculated as Im ← Im + α. Next, it is determined whether or not the motor supercharging flag is 0 (step 235). The motor supercharging flag is a flag indicating whether or not supercharging by the turbo motor 11a is being performed (whether the supercharging pressure is rising). If “1”, supercharging by the turbo motor 11a is performed. “0” indicates that turbocharging by the turbo motor 11a is not performed (including a situation where the supercharging pressure is not sufficiently raised).

  When step 235 is affirmed, it can be said that the turbocharging by the turbo motor 11a has not yet started, and the situation starts from the energization amount Im determined in step 230. In this case, the controller (rotation speed detecting means) 21 detects the motor rotation speed Nm (step 240), and stores this rotation speed Nm as Nm0 in the RAM in the ECU 16 (or a storage area in the controller 21) (step 240). 245). After storing Nm0, the motor energization amount Im calculated in step 230 is energized to the turbo motor 11a to promote supercharging (step 250). Immediately after the start of supercharging promotion by the turbo motor 11a, the valve 28 of the exhaust side bypass 27 is opened (step 225). By doing so, the exhaust flow bypasses the turbine wheel of the turbocharger 11.

  Then, the rotational speed Nm of the turbo motor 11a is detected again (step 260), and it is determined whether the rotational speed Nm exceeds the rotational speed (Nm0 + β) obtained by adding the predetermined rotational speed β to the rotational speed Nm0 stored in step 245. (Step 265). That is, it is determined whether or not the supercharging pressure has risen reliably after the start of driving of the turbo motor 11a based on the increase width β of the rotational speed of the turbo motor 11a. In the present embodiment, it is determined that the boost pressure has risen when the rotational speed Nm of the turbo motor 11a increases by the predetermined rotational speed β. However, depending on whether or not the rotational speed Nm of the turbo motor 11a has reached the predetermined rotational speed. You may determine whether the supercharging pressure rose. The predetermined rotational speed at this time may be a fixed value, or may be a value that varies based on values such as the engine rotational speed and the accelerator opening.

  Here, whether or not the supercharging pressure has risen is determined based on the rotational speed Nm of the turbo motor 11a. However, in step 260, the actual supercharging pressure is redetected by the pressure sensor 19, and this redetected actual value is detected. It can also be determined whether the boost pressure has risen based on the boost pressure. In this case as well, the determination may be made based on the pressure increase width from the actual boost pressure Rp detected in step 210, or by determining whether or not the re-detected actual boost pressure Rp has reached a predetermined pressure. Also good. The predetermined pressure may be a fixed value or a variable value, as in the case described above.

  If step 265 is negative, the process returns to step 260 and is repeated until Nm> (Nm0 + β) is satisfied, that is, until it is determined that the boost pressure has risen. On the other hand, when step 265 is affirmed, it can be determined that the supercharging pressure has risen due to the supercharging assist by the turbo motor 11a, and therefore, the above-described motor supercharging flag is set to “1”, and FIGS. The flowchart is temporarily terminated.

  Here, after the supercharging assist by the turbo motor 11a is started, the valve 28 of the exhaust side bypass passage 27 remains open until it is determined that the supercharging pressure has risen sufficiently [steps 250 to 265]. . For this reason, since the exhaust flow bypasses the turbine wheel until the boost pressure rises, the exhaust resistance does not increase and the fuel efficiency does not deteriorate. Moreover, since the supercharging assist is performed by driving the turbo motor 11a, the supercharging effect is obtained.

  On the other hand, after “1” is set to the motor supercharging flag in step 270, that is, when supercharging assist by the turbo motor 11a has already been performed, and the actual supercharging pressure Rp is the target supercharging pressure. If Tp has not been reached (after step 220 is negative and step 235 is also negative), the turbo motor 11a is driven by the motor energization amount Im newly added at step 225 and step 230 (step 235). 275). At this time, since the supercharging pressure has already risen, the valve 28 of the exhaust side bypass 27 is closed, and the supercharging effect by the turbo motor 11a and the supercharging effect by the exhaust flow are used in combination.

  While the supercharging by the turbo motor 11a is continued, the actual supercharging pressure Rp exceeds the target supercharging pressure Tp. In this case, step 220 is affirmed in the flowcharts of FIGS. In this case, that is, when the difference Ep is a negative value and the actual supercharging pressure Rp is larger than the target supercharging pressure Tp, it can be determined that the turbocharging by the turbo motor 11a is no longer necessary, so that FIG. As shown in FIG. 5, first, the energization amount Im to the turbo motor 11a is subtracted by a predetermined width γ (step 285). At this time, the lower limit of the motor energization amount Im is guarded to zero. Specifically, it is determined whether or not the motor energization amount Im subtracted in step 285 is negative (step 290). If the motor energization amount Im is negative, the motor energization amount Im is set to zero (step 295). In this case, since the turbo motor 11a is not energized, the motor supercharging flag is set to “0” (step 300). After step 290 is affirmed and step 295 and step 300 described above are completed, or when step 290 is denied, the determined motor energization amount Im is passed through the turbo motor 11a (motor energization amount Im = 0) (step 305).

  After step 305, it is determined whether or not the target boost pressure Tp exceeds a predetermined pressure ε (step 310). This predetermined pressure ε is set as a supercharging pressure at the boundary of whether or not the turbine wheel becomes exhaust resistance. When the target boost pressure Tp is high to some extent and the boost pressure is controlled based on this, it can be determined that the turbine wheel does not act as a large exhaust resistance. On the contrary, if the target boost pressure Tp is lowered to some extent, the turbine wheel may act as a large exhaust resistance when the boost pressure is controlled based on this.

  Therefore, when step 310 is affirmed, the valve 28 of the exhaust-side bypass 27 is closed (step 315), and both the supercharging effect by driving the turbo motor 11a and the supercharging effect by the exhaust flow are obtained. The driving amount by the turbo motor 11a is gradually reduced while obtaining the above. On the other hand, when step 310 is denied, the valve 28 of the exhaust side bypass 27 is opened to gradually reduce the supercharging effect by the turbo motor 11a while avoiding the turbine wheel from becoming exhaust resistance.

  In addition, this invention is not limited to embodiment mentioned above. For example, in the above-described embodiment, the valves 25 and 27 adjust the flow rate by controlling the open / close DUTY ratio. However, the flow rate of these valves may be adjusted not by DUTY control, such as the throttle valve 13, but by adjusting the amount of opening. Further, in the present invention, shutting off the exhaust side bypass passage 27 means substantially eliminating the exhaust flow flowing through the exhaust side bypass passage 27. In other words, even when there is a slight flow, if the exhaust flow passing through the exhaust side bypass 27 is substantially restricted, this corresponds to the interruption according to the present invention.

It is a block diagram which shows the structure of the internal combustion engine (engine) which has one Embodiment of the control apparatus of this invention. It is a flowchart (first half part) of the supercharging control by one Embodiment of the control apparatus of this invention. It is a flowchart (the second half part 1) of the supercharging control by one Embodiment of the control apparatus of this invention. It is a flowchart (second half part 2) of the supercharging control by one Embodiment of the control apparatus of this invention. It is a map used when determining a target supercharging pressure.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Engine (internal combustion engine), 2 ... Intake passage, 3 ... Cylinder, 4 ... Injector, 5 ... Piston, 6 ... Spark plug, 7 ... Intake valve, 8 ... Exhaust passage, 9 ... Exhaust valve, 10 ... Air cleaner, 11 ... turbocharger, 11a ... turbo motor (electric motor), 13 ... throttle valve, 14 ... accelerator pedal, 15 ... accelerator position sensor, 16 ... ECU (control means), 19 ... pressure sensor (actual boost pressure detection means), 21 ... Controller (rotational speed detection means) 24... Intake side bypass path, 25... Valve, 26... Crank positioning sensor, 27.

Claims (4)

In a control device for an internal combustion engine provided with a turbocharger in which a compressor wheel is arranged on an intake passage and a turbine wheel is arranged on an exhaust passage,
An electric motor capable of rotationally driving the compressor wheel; a bypass path provided to the exhaust passage so as to bypass the turbine wheel; an opening / closing means for opening / closing the bypass path; the electric motor and the opening / closing means; And control means for controlling
The control device of the internal combustion engine, wherein the control means opens the bypass passage by the opening / closing means until a boost pressure rises after the start of driving of the electric motor.   2. The control apparatus for an internal combustion engine according to claim 1, wherein the control means shuts off the bypass passage by the opening / closing means when a supercharging pressure rises after the start of driving of the electric motor.   The apparatus further comprises a rotation speed detection means for detecting the rotation speed of the electric motor, and determines whether or not the supercharging pressure of the electric motor has risen based on the rotation speed of the electric motor detected by the rotation speed detection means. 3. The control apparatus for an internal combustion engine according to claim 1, wherein the control apparatus is an internal combustion engine.   An actual boost pressure detecting means for detecting an actual boost pressure of the internal combustion engine is further provided, and the boost pressure of the electric motor rises based on the actual boost pressure detected by the actual boost pressure detecting means. 3. The control device for an internal combustion engine according to claim 1 or 2, wherein it is determined whether or not.

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