JP4306483B2 - Control device for internal combustion engine having supercharger with electric motor - Google Patents

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. In the internal combustion engine described in [Patent Document 1], the intake passage is once branched and then merged again. And the supercharger with an electric motor is arrange | positioned on one branch passage. Furthermore, a switching valve is also provided for opening (branching the other branch path) / blocking (opening the other branch path) the branch path in which the supercharger is disposed.
JP-T-2001-518590

  In the internal combustion engine described in [Patent Document 1] described above, no consideration is given to detecting a failure of the switching valve. For this reason, it is not possible to take an appropriate action when the switching valve fails. Accordingly, an object of the present invention is to provide a control device for an internal combustion engine that can accurately determine a failure of a valve (switching valve or on-off valve) that switches an intake passage in a supercharger with an electric motor.

The control apparatus for an internal combustion engine according to claim 1 bypasses the supercharger, an electric motor that electrically drives the supercharger, and a supercharger disposed on an intake passage of the internal combustion engine mounted on the vehicle. In this way, an electric supercharging means having a bypass path having both ends connected to the intake passage and an on-off valve for opening and closing the bypass path, a pressure detection means for detecting the pressure in the intake passage on the downstream side of the supercharger, and pressure detection Based on the pressure value detected by the means, the divergence degree acquisition means for acquiring the degree of divergence of the supercharged state by the electric supercharging means from the desired supercharging state, and the divergence degree acquired by the divergence degree acquisition means when the supercharging insufficient side is a predetermined degree of deviation or more, off valve failure judgment means to judge that a failure, the downstream turbocharger disposed downstream of the supercharger on the intake passage, The target for calculating the target intake pressure of the internal combustion engine Intake pressure calculating means, and variable supercharging for changing the supercharging state by the downstream supercharger based on the deviation between the pressure value detected by the pressure detecting means and the target intake pressure calculated by the target intake pressure calculating means Provided with a mechanism, the pressure detection means detects the pressure in the intake passage on the downstream side of the downstream supercharger, and the failure determination means has a control amount that is greater than a predetermined control amount when the supercharging state is changed by the variable supercharging mechanism. The on / off valve is determined to be malfunctioning, the control amount associated with the supercharging state change to the supercharging increasing side by the variable supercharging mechanism is greater than or equal to a predetermined amount, and the engine speed is If it is in the high rotation range, it is determined that the on-off valve is stuck in the closed state, the control amount associated with the supercharging state change to the supercharging increasing side by the variable supercharging mechanism is a predetermined amount or more, and When the engine speed is in the low speed range, the open / close valve is open. When it is determined that the open / close valve is stuck in the closed state or the open state by the limiting means for limiting the control amount by the variable supercharging mechanism to a predetermined range and the failure judging means Further, the present invention is characterized by further including a restriction relaxation means for relaxing the restriction by the restriction means .

According to the control apparatus for an internal combustion engine according to claim 1, how far the actual supercharging state differs from the intended supercharging state based on the pressure in the intake passage (intake pressure, supercharging pressure). (The degree of deviation) is acquired, and it is determined that the on-off valve is malfunctioning when the degree of deviation is greater than or equal to a predetermined value on the supercharging underside. By doing so, it is possible to accurately detect a failure of the on-off valve and take an appropriate countermeasure. Note that the degree of deviation may be any value as long as it is a value determined based on the pressure value in the intake passage. For example, the difference between the detected intake pressure and the target intake pressure may be adopted as the degree of deviation. Examples of superchargers here include those that drive a compressor wheel with an electric motor, what is called a supercharger that pumps intake air using an electric motor, and those that incorporate an electric motor in a turbine / compressor wheel of a turbocharger. Can do. Further, in addition to the electric motor supercharger on the upstream side, a supercharger is provided on the downstream side, and the downstream supercharger is provided with a mechanism (variable supercharging mechanism) for variably controlling the supercharging state. The pressure detection means detects the pressure in the intake passage on the downstream side of the downstream supercharger, and when the control amount of the variable supercharging mechanism (corresponding to the above-mentioned divergence degree) is a predetermined amount or more on the supercharging increase side, Judge that the on-off valve is faulty. The failure can be accurately detected by determining the failure based on the control amount of the variable supercharging mechanism determined based on the pressure in the intake passage. An example is a case where the downstream supercharger is a turbocharger and the variable supercharging mechanism is a variable nozzle mechanism. An example of the variable supercharging mechanism is an electronically controlled waste gate valve. Also, rather than simply detecting that the on-off valve is malfunctioning, is the change in the control amount of the variable supercharging mechanism more than a predetermined amount on the boost side, in the high or low speed range? Based on the above, the failure mode of the on-off valve can also be specified.

  A first 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 supercharger 29 with a motor (electric motor) 29a, a turbocharger (downstream supercharger) 11, an intercooler 12, a throttle valve 13 and the like are arranged from the upstream side. Yes. The supercharger 29 functions as electric supercharging means.

  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 supercharger 29 with the motor 29a is a supercharger that performs supercharging by supercharging the motor 29a with electric energy. In the supercharger 29, the above-described motor 29a is incorporated so that the rotation shaft of the compressor wheel becomes the output shaft. It is possible to perform supercharging by driving the motor 29a.

  The motor 29a can also function as a generator that generates power using intake energy, and is sometimes called a motor generator because it has the functions of a motor and a generator. The motor 29a has a rotor fixed to the rotating shaft of the compressor wheel and a stator disposed around the rotor as main components. The turbocharger 11 disposed on the downstream side of the supercharger 29 has its compressor wheel disposed on the intake passage 2 and its turbine wheel disposed on the exhaust passage 8. Is a normal turbocharger.

  The turbocharger 11 includes a variable nozzle mechanism 11a as a variable supercharging mechanism. The variable nozzle mechanism 11a has a plurality of vanes arranged outside the turbine wheel, and is a mechanism that variably controls the supercharging state by changing the flow velocity of the exhaust flow corresponding to the turbine by changing the vane angle. . When the opening degree of the vane (variable nozzle opening degree) is controlled to the closing side, the flow rate of the exhaust flow that hits the turbine is increased and the supercharging effect is enhanced.

  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 with the increase in pressure due to supercharging by the turbocharger 29 or 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. Thus, the opening degree of the throttle valve 13 is determined by an electronic control unit (ECU) 16 described later. The throttle valve 13 is opened and closed by a throttle motor 17 that is provided in association therewith. In addition, a throttle position sensor 18 for detecting 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 (pressure detection means) 19 for detecting the pressure (supercharging pressure / intake pressure) in the intake passage 2 is disposed. The pressure in the intake passage 2 (supercharging pressure / intake pressure) may be detected by an intake manifold portion or the like.

  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 position sensor 26 for detecting the rotational position of the crankshaft is attached in the vicinity of the crankshaft of the engine 1. The crank position sensor 26 can also detect the engine speed Ne from the 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 controller 16 of the motor 29a described above is also connected to the ECU 16, and the ECU 16 and the controller 21 emphasize and control the motor 29a. The controller 21 can also detect the number of rotations of the motor 29a. The controller 21 is also connected to a battery 22 that stores electrical energy supplied to the motor 29a. 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 motor 29 a is possible, and the electric power generated by the motor 29 a is stored in the battery 22 via the controller 21. The ECU 16 functions as divergence degree acquisition means, failure determination means, target intake pressure calculation means, restriction means, and restriction relaxation means. The controller 21 functions as a drive prohibiting unit together with the ECU 16.

  An intake side bypass passage 24 is provided so as to bypass the supercharger 29 described above. A valve (open / close valve) 25 for opening and closing the intake side bypass passage 24 is disposed on the intake side bypass passage 24. The valve 25 of the present embodiment is an electromagnetic valve, but may be a throttle type valve as long as the intake side bypass passage 24 can be opened and shut off. Further, if the opening and closing of the valve 25 can be controlled by DUTY, the flow rate can be adjusted by the DUTY ratio. The operation of the valve 25 is electrically controlled based on a signal from the ECU 16. If the valve 25 is fully opened, if the compressor wheel of the supercharger 29 has an intake resistance, the intake air passes through the intake side bypass path 24 having no (or less) intake resistance, and the intake air moves downstream. Flowing.

  An exhaust side bypass passage 27 is provided so as to bypass the above-described exhaust side turbine wheel of the turbocharger 11, and a waste gate valve 28 is disposed on the exhaust side bypass passage 27. A normal wastegate valve is intended to allow the exhaust flow to bypass the turbine if it is too high and the pressure downstream of the turbocharger compressor wheel opens. This avoids excessive supercharging. The waste gate valve 28 of the present embodiment is of an electronic control type, and is opened / closed by a command from the ECU 16.

  Next, failure diagnosis control of the valve 25 in the control device described above will be described. Flow charts for this control are shown in FIGS. The control of the flowchart shown in FIGS. 2 and 3 is repeatedly executed. First, it is determined whether or not the drive prohibition flag of the motor 29a is 0 (drive permission) (step 200). When the flag is 1 and driving is prohibited, the control of the flowcharts of FIGS. 2 and 3 is finished. On the other hand, if the flag is 0 and the driving of the motor 29a is not prohibited, the engine speed Ne is detected by the crank position sensor 26 and the engine load is detected (step 205). The engine load is obtained from the intake air amount detected by the air flow meter 20 and the throttle opening detected by the throttle position sensor 18.

  Next, based on the engine speed Ne and the engine load, a drive command value for the motor 29a is determined on the basis of a map created in advance by experiments or the like and stored in the ROM of the ECU 16, and output to the motor 29a. (Step 210). The drive command value is given as, for example, the amount of supplied power (current value) or the rotation speed of the motor 29a. An example of the map described above is shown in FIG. The supercharger 29 with the motor 29a is mainly intended to compensate for supercharging in a low and medium load range where a sufficient supercharging effect cannot be obtained depending on the turbocharger 11, and the engine speed is low and the engine load is low. The lower the is, the greater the amount of power supplied to the motor 29a. On the other hand, when the engine speed is high and the engine load is high, the turbocharger 11 can sufficiently obtain the supercharging effect, and conversely, the capacity of the motor 29a becomes insufficient, so that the amount of power supplied to the motor 29a is reduced. The The upstream supercharger 29 starts supercharging based on this command value.

  Similarly, based on the engine speed Ne and the engine load, an atmospheric pressure correction standard variable variable that becomes a control amount of the variable nozzle mechanism 11a based on a map that is created in advance by experiments or the like and stored in the ROM of the ECU 16. The nozzle opening VN0 is determined and output as a variable nozzle opening command value VN to the variable nozzle mechanism 11a (step 215). An example of the map described above is shown in FIG. As described above, in the turbocharger 11, it is difficult to obtain a sufficient supercharging effect in the low and medium load range. Therefore, the lower the engine speed and the lower the engine load, the smaller the atmospheric pressure correction standard variable nozzle opening VN0 is set (to the closed side), and the exhaust flow rate flowing into the turbine section is increased to improve the supercharging effect. . On the other hand, when the engine speed is high and the engine load is high, an exhaust flow with a sufficient flow rate and flow rate can be secured, so an atmospheric pressure correction standard variable nozzle can be used to obtain an optimum supercharging effect while preventing excessive supercharging. The opening degree VN0 is set to gradually increase (open side).

  The atmospheric pressure correction standard variable nozzle opening VN0 is corrected by the atmospheric pressure detected by an atmospheric pressure sensor (not shown). Further, instead of the engine load, the accelerator position TA may be used by the accelerator position sensor 15. After step 215, the intake (supercharging) pressure Pd expected to be obtained by setting the variable nozzle opening to VN0 is obtained (step 220). Here, the desired intake (supercharging) pressure Pd is obtained as a function f (VN0) of the atmospheric pressure correction standard variable nozzle opening VN0.

  After step 220, the actual intake (supercharging) pressure P1 is now detected by the pressure sensor 19 (step 225). Next, based on the difference between the desired intake pressure Pd and the actual intake pressure P1, a correction amount VNc for the variable nozzle opening VN is calculated (step 230). Here, the correction amount VNc is obtained as a function f (Pd−P1) of the difference (Pd−P1) described above. The control amount of the variable nozzle opening VN is VN0 + VNc. The greater the difference (Pd−P1), the greater the correction amount VNc. When the difference (Pd−P1) is small and the actual intake pressure P1 is close to the desired intake pressure Pd, the correction amount VNc is small.

  After step 230, it is first determined whether or not the corrected variable nozzle opening (VN0 + VNc) is a negative value (step 235). Since the minimum opening of the variable nozzle opening VN is 0, in this case, VNc is set to 0−VN0 (step 240). As a result, VN0 + VNc = VN0 + (0−VN0) = 0, and the variable nozzle opening VN is set to 0, which is the minimum opening. On the other hand, if step 230 is negative, it is determined whether or not the corrected variable nozzle opening (VN0 + VNc) exceeds 100 (step 245). Since the maximum opening of the variable nozzle opening VN is 100, in this case, VNc is set to 100-VN0 (step 250). As a result, VN0 + VNc = VN0 + (100−VN0) = 100, and the variable nozzle opening VN is set to 100 which is the maximum opening. In this way, the upper and lower limits of the variable nozzle opening VN are guarded by changing the value of the correction amount VNc.

  If step 245 is negative, the corrected variable nozzle opening (VN0 + VNc) is between 0 and 100, so that value is maintained. After step 240, 250 or step 245 is negated, in order to guard the lower limit of the correction amount VNc itself, it is determined whether or not the correction amount VNc is less than the lower limit guard value Gu (step 255). This lower limit guard value Gu is used to prevent the turbocharger 11 from rotating beyond the allowable rotational speed in order to prevent excessive charging to the closed side of the variable nozzle 11a and prevent overcharging, or to prevent the turbocharger 11 from rotating beyond the allowable rotational speed. Is to do. However, the lower limit guard value Gu is variably controlled depending on the situation, such as when the desired boost pressure is not reached even after correction. The initial value of the lower limit guard value Gu is, for example, −10.

  If step 255 is denied and the correction amount VNc is equal to or greater than the lower limit guard value Gu, it can be determined that the correction amount VNc is not so small that it is lower than the lower limit guard value Gu. Can be determined to function normally (step 260). In this case, the control of the flowcharts of FIGS. 2 and 3 is temporarily terminated. On the other hand, if the correction amount VNc is less than the lower limit guard value Gu, the correction amount VNc is guarded with the lower limit guard value Gu (the lower limit guard value Gu is substituted into the correction amount VNc) (step 265). Even when VNc after the change in steps 240 and 250 is less than the lower limit guard value Gu, the correction amount VNc is changed to the lower limit guard value Gu.

  Then, the counter Cg is incremented (counted up) (step 270). This counter Cg counts how long the situation where the correction amount VNc exceeds the lower limit value. In other words, this counter Cg determines whether or not the correction amount VNc for correcting the variable nozzle opening VN is stuck to the lower limit guard value Gu (the limit value for correcting the variable nozzle 11a to be closed). Monitoring. After step 270, whether or not the counter Cg exceeds the predetermined value Cg0, that is, whether or not the situation where the correction amount VNc exceeds the lower limit guard value Gu beyond the period defined by the predetermined value Cg0 continues. Determination is made (step 275).

  If step 275 is negative, the control of the flowcharts of FIGS. 2 and 3 is temporarily terminated. On the other hand, when the counter Cg exceeds the predetermined value Cg0, it can be determined that the supercharging is insufficient and the situation in which the supercharging is increased by the variable nozzle 11a of the turbocharger 11 continues. That is, it can be determined that the output torque of the engine 1 is lower than the desired torque, and that further output enhancement is required, and this can be determined because the valve 25 is out of order. In this case, in order to determine the failure mode of the valve 25, first, it is determined whether or not the engine speed Ne is equal to or less than a predetermined speed Ne0 (step 280). Here, it is preferable to re-detect the engine speed Ne by the crank position sensor 26 again.

  In the present embodiment, a supercharger 29 with a motor 29 a is disposed on the upstream side of the turbocharger 11. If only turbocharging by the turbocharger 11 is performed, the turbo lag in the low and medium rotation range (low and medium load range) tends to become prominent. Therefore, in such a low and medium rotation range (low and medium load range), the motor 29a is driven to compensate for the output, and a good output is obtained over the entire range from the low rotation to high rotation range (low load range to high load range). Trying to get. At this time, in the low / medium speed range (low / medium load range), the intake flow supercharged by the supercharger 29 with the valve 25 closed is prevented from blowing back to the upstream side by the bypass passage 24, and the supercharging effect is ensured. Control is obtained as obtained. On the other hand, in this case, the capacity of the supercharger 29 is limited in order to compensate for the low / medium rotation range (low / medium load range). In the high rotation range (high load range), the intake resistance is changed due to insufficient capacity. It becomes. Therefore, in the high speed range (high load range), control is performed such that the valve 25 is opened and the bypass passage 24 is opened, and the intake air bypasses the supercharger 29 so that the turbocharger 11 can reliably obtain the supercharging effect. Made.

  As described above, when step 275 is positive, it can be determined that the torque has continued to decrease and the valve 25 on the bypass path 24 has failed. In this case, in order to determine the failure mode, it is determined in step 280 whether or not the engine rotational speed Ne is equal to or lower than the predetermined rotational speed Ne0. As the failure mode, there are a case where the valve 25 is stuck in an open state and a case where it is stuck in a closed state. If the valve 25 is fixed in a state where the valve 25 is fully open or close to full open, the supercharging blowback to the upstream side by the bypass path 24 occurs in the low and middle rotation range, and a torque drop occurs with respect to the torque that should originally be obtained. However, since the intake air can bypass the supercharger 29 in the high speed range, there is no particular problem. On the other hand, if the valve 25 is fixed in a fully closed state or nearly fully closed state, there is no particular problem because the supercharging blowback to the upstream side by the bypass passage 24 is prevented in the low and middle rotation range. However, the intake air cannot bypass the supercharger 29 in the high speed range, and a torque drop occurs with respect to the torque that should originally be obtained.

  The predetermined rotational speed Ne0 in step 280 is set as a threshold value that serves as a reference for determining whether the rotational speed range is low or medium. If step 280 is affirmed, it is determined that a torque drop has occurred in the low and middle rotation regions, and in this case, it can be determined that the valve 25 is open and has failed (step 285). In the case of a failure due to sticking in the open state (open fail), the counter Cf is incremented (counted up) here (step 290). This counter Cg counts how long the state of the open failure is maintained. After step 290, it is determined whether or not the counter Cf exceeds a predetermined value Cf0 (step 295).

  If the state of the open failure continues for a predetermined period or longer, even if the motor 29a is driven, the intake air blows back to the upstream side and can continue to be driven without the boost pressure reaching the desired boost pressure. High nature. For this reason, when step 295 is affirmed, 1 which shows prohibiting the drive of the motor 29a is set to a motor drive prohibition flag (step 300). If step 295 is negative, 1 is not set in the motor drive prohibition flag, and the control of the flowcharts of FIGS. 2 and 3 is terminated. However, if the open fail continues, step 295 will be denied.

  On the other hand, if step 280 is negative, it is determined that a reduction in supercharging occurs in the high engine speed range, and in this case, it can be determined that the valve 25 is closed and malfunctions (step 305). In the case of a failure due to sticking in the closed state (closed fail), the limitation of the variable nozzle 11a is relaxed in order to improve the supercharging effect by the turbocharger 11 in the high rotation range. Specifically, the lower limit guard value Gu of the correction amount VNc described above is further reduced so that the opening degree of the variable nozzle 11a can take a smaller value. Here, Gu-20 is set as the new current lower limit guard value Gu (step 310).

  Here, the control restriction of the variable nozzle 11a is relaxed only during the closed failure. This is because the supercharging effect can be expected to be improved by the turbocharger 11 in the high rotation range if it is a closed failure. On the other hand, the torque is insufficient in the low and medium rotation range at the time of open failure, and even if the control restriction of the variable nozzle 11a is relaxed, it seems that the benefit of improving the supercharging effect by the turbocharger 11 is not as high as in the high rotation range. However, the control restriction of the variable nozzle 11a may be relaxed even during the open failure. An example of control in this case is shown in FIG. The flowchart shown in FIG. 6 replaces FIG. 3, and the first half of the control is step 200 to step 250 shown in FIG. In the flowchart of FIG. 6, steps having the same contents as those in the flowchart of FIG. 3 are denoted by the same step numbers.

  In this control, when step 275 is affirmed and it is determined that the situation in which the correction amount VNc exceeds the lower limit guard value Gu exceeds the period defined by the predetermined value Cg0, Gu-20 is set. The new current lower limit guard value Gu is set (step 315). As described above, when it is determined that the torque shortage has occurred, the control restriction of the variable nozzle 11a may be relaxed immediately to improve the torque by the variable nozzle 11a. Further, in this embodiment, the failure state is classified in more detail using the value of the lower limit guard value Gu. That is, after the step 315, the above-described step 280 is executed, and thereafter, it is determined whether or not the lower limit guard value Gu is -80 or less (steps 320 and 335).

  First, a case will be described in which step 280 is affirmed and torque reduction occurs in the low and middle rotation ranges. In this case, in step 320, it is determined whether or not the lower limit guard value Gu is −80 or less. The correction amount VNc is a value for correcting the variable nozzle opening degree VN that takes a value between 0 and 100, and its possible range is between -100 and 100. The lower limit guard value Gu that guards the lower limit of the correction amount VNc being −80 or less means that the correction to the closing side is considerably necessary. For this reason, when step 320 is affirmed, a sufficient supercharging effect is not obtained in the low / medium rotation range even though the variable nozzle opening VN is moderately reduced to the closed side. It can be judged that there is. In such a case, even if it is an open failure, it is determined that the valve 25 is a fully open fail that is fixed in a fully open state (step 325).

  On the other hand, when the result of step 320 is negative, it is determined that the battery is not fully opened but is open fail (step 330). Even in the case of a full open failure, it is determined in step 330 that it is a simple open failure until the lower limit guard value Gu is updated to -80 or less. In this embodiment, the drive prohibition flag of the motor 29a is set based on the counter Cf described above only when the fully open fails, and the drive of the motor 29a is not prohibited during the simple open fail. In this manner, the driving of the motor 29a may be prohibited only when the power consumption by the motor 29a is particularly significant.

  Next, the case where step 280 is denied and torque reduction occurs in the high rotation range will be described. In this case as well, in step 335, it is determined whether or not the lower limit guard value Gu is −80 or less. As described above, the lower limit guard value Gu being equal to or less than −80 means that the correction to the closing side is considerably necessary. For this reason, when step 335 is affirmed, it is a situation where a sufficient supercharging effect is not obtained in the high rotation range even though the variable nozzle opening VN has been considerably relaxed to the closed side. It can be judged. In such a case, even if it is a closed failure, it is determined that the valve 25 is a fully closed failure that is fixed in a fully closed state (step 340).

  On the other hand, if step 335 is negative, it is determined that the battery is not fully closed but a closed failure (step 345). Even in the case of a fully-closed fail, it is determined in step 340 that it is a mere closed fail until the lower limit guard value Gu is updated to -80 or less. In this embodiment, when a failure on the closed side of the valve 25 is predicted, the control restriction of the variable nozzle 11a is relaxed in advance. That is, in this embodiment, when a failure on the closed side or the open side of the valve 25 is predicted, the control restriction of the variable nozzle 11a is relaxed before the failure mode is determined (determined). It doesn't matter.

  Next, another embodiment of the present invention will be described. FIG. 7 shows a diagram corresponding to FIG. 1 of the present embodiment. In addition, the same code | symbol is attached | subjected to the component which is the same as that of embodiment of FIG. 1, or the detailed description is abbreviate | omitted. The engine 1 of the embodiment of FIG. 1 is mainly configured with the idea that supercharging in the low and medium rotation range is performed by a supercharger 29 with a motor 29a, and supercharging in the high rotation range is performed by the turbocharger 11. . For this reason, the capacity | capacitance of the supercharger 29 was selected for the purpose of supercharging in the low and medium speed range. In contrast, in the present embodiment, only one supercharger 30 is arranged on the intake passage 2. The supercharger 30 includes a motor 30a.

  The engine 1 of the present embodiment has a specification with high-rotation type tuning, and functions as a naturally aspirated engine using the bypass path 24 in the high-rotation range. On the other hand, since the engine 1 has a high rotation specification, the torque in the low and medium rotation range is thin, and this is compensated by supercharging by the supercharger 30. For this reason, in the case of the present embodiment, the capacity of the supercharger 30 and the performance of the motor 30a are selected mainly focusing on the performance in the low / medium rotation range.

  The failure diagnosis control of the valve 25 in the control device of this embodiment will be described. A flowchart of this control is shown in FIG. The control of the flowchart shown in FIG. 8 is repeatedly executed. First, it is determined whether or not the drive prohibition flag of the motor 30a is 0 (drive permission) (step 700). When the flag is 1 and driving is prohibited, the control of the flowchart of FIG. On the other hand, if the flag is 0 and the driving of the motor 30a is not prohibited, the engine speed Ne is detected by the crank position sensor 26 and the engine load is detected (step 705). Next, on the basis of the engine speed Ne and the engine load, a drive command value i for the motor 30a is determined based on a map created in advance by experiments or the like and stored in the ROM of the ECU 16, and the motor 30a is determined. Is output (step 710: see FIG. 4). The supercharger 30 starts supercharging based on this command value.

  After step 710, an intake (supercharge) pressure Pd expected to be obtained by driving the supercharger 30 is obtained (step 715). Here, the desired intake (supercharging) pressure Pd is obtained as a function f (i) of the command value i to the motor 30a. After step 715, the actual intake (supercharging) pressure P1 is detected by the pressure sensor 19 (step 720), and the difference (Pd−P1) between the desired intake pressure Pd and the actual intake pressure P1 is a predetermined value α (positive Value) is exceeded (step 725). That is, here, the supercharged state by the supercharger 30 is detected as the actual intake pressure P1, the desired supercharged state is represented by the desired intake pressure Pd, and the difference between the two (Pd− P1).

  That the degree of difference [difference (Pd−P1)] is larger than the predetermined value α is a situation where the actual intake pressure P1 is deviated to a lower side with respect to the intended intake pressure Pd. It can be determined that the torque is insufficient. On the contrary, if the degree of divergence [difference (Pd−P1)] is equal to or less than the predetermined value α, it is determined that the actual intake pressure P1 is close to the intended intake pressure Pd and the valve 25 is normal ( Step 730). If step 725 is negative, in order to determine the failure mode of the valve 25, it is first determined whether or not the engine speed Ne is equal to or lower than a predetermined speed Ne0 (step 735). Here, it is preferable to re-detect the engine speed Ne by the crank position sensor 26 again.

  In this case, in order to determine the failure mode of the valve 25, first, it is determined whether or not the engine speed Ne is equal to or less than a predetermined speed Ne0 (step 280). Here, it is preferable to re-detect the engine speed Ne by the crank position sensor 26 again. As described above, the engine 1 of the present embodiment has been subjected to high-rotation type tuning, and compensates for a shortage of torque in the low and medium rotation range by supercharging by the supercharger 30. For this reason, when the valve 25 is fixed in a state where the valve 25 is fully opened or close to the fully opened state, the supercharging blowback to the upstream side by the bypass passage 24 occurs in the low and middle rotation range, and the torque is reduced with respect to the torque that should originally be obtained. . However, since the intake air can bypass the supercharger 30 in the high speed range, there is no particular problem. On the other hand, if the valve 25 is fixed in a fully closed state or nearly fully closed state, there is no particular problem because the supercharging blowback to the upstream side by the bypass passage 24 is prevented in the low and middle rotation range. However, the intake air cannot bypass the supercharger 30 in the high rotation range, and a torque drop occurs with respect to the torque that should originally be obtained.

  If step 735 is affirmed, it is determined that a reduction in supercharging has occurred in the low-medium rotation range, and in this case, it can be determined that the valve 25 is open and has failed (step 740). In the case of a failure due to sticking in the open state (open fail), the counter C is incremented (counted up) here (step 745). This counter C counts how long the state of the open failure is maintained. After step 745, it is determined whether or not the counter C exceeds a predetermined value C0 (step 750). If the open fail state continues for a predetermined period or longer, even if the motor 30a is driven, the intake air blows back upstream, and the boost pressure does not reach the desired boost pressure and can continue to be driven. High nature. For this reason, when step 750 is affirmed, 1 which shows prohibiting the drive of the motor 30a is set to a motor drive prohibition flag (step 755).

  If step 750 is negative, 1 is not set in the motor drive prohibition flag, and the control of the flowchart of FIG. 8 ends. However, if the open fail continues, step 750 is eventually denied. On the other hand, if step 735 is negative, it is determined that a reduction in supercharging has occurred in the high speed range, and in this case, it can be determined that the valve 25 is closed and has failed (step 760). Thus, even when the turbocharger 30 with the motor 30a is used alone, it is possible to determine the failure of the valve 25 that opens and closes the bypass path 24.

  In the present embodiment, the high-rotation engine 1 and the supercharger 30 that compensates for the torque in the low and medium rotation range are used in combination. However, the capacity of the supercharger 30 and the performance of the motor 30a may be selected as being capable of supercharging in a well-balanced manner from a low rotation range (low load) to a high rotation range (high load). However, since there is a situation where it is not necessary to drive the motor 30a, such as during idling, in such a case, intake air is bypassed by the bypass path 24, and consumption of electrical energy is suppressed. Alternatively, it may be used as a naturally aspirated engine using the bypass path 24 in the low and medium rotation range and drive the motor 30a only in the high load / high rotation range to perform supercharging to obtain a high output. In this case, the capacity of the supercharger 30 and the performance of the motor 30a are selected mainly focusing on performance in a high load / high rotation range.

  Also in these cases, the failure of the valve 25 is determined based on the intake pressure in each operation state. If the motor 30a is driven and the torque is reduced in the operation state in which the valve 25 is closed, it can be determined that the valve 25 is open. Further, although depending on the capacity of the motor 30a, it can be determined that the valve 25 is closed if there is a torque drop in an operation state where the valve 25 is opened when the capacity of the motor 30a is insufficient.

  The present invention is not limited to the embodiment described 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 above-described embodiment of FIG. 1, the control example using the variable nozzle 11a as the variable supercharging mechanism has been described. However, it is also possible to use an electronically controlled waste gate valve 28 as the variable supercharging mechanism (in this case, the variable nozzle 11a may not be present). Since the waste gate valve 28 in the embodiment of FIG. 1 described above is electronically controlled, the supercharging pressure (supercharging situation) can be controlled by adjusting the opening degree. For example, the opening degree of the waste gate valve 28 can be controlled by a DUTY signal.

  If the opening degree of the waste gate valve 28 is opened so that the exhaust flow bypasses the turbocharger 11, the supercharging effect can be reduced. On the other hand, if the opening degree of the waste gate valve 28 is closed, it can be used (can be increased) without reducing the supercharging effect due to the exhaust flow. In this way, the electronically controlled waste gate valve 28 is used as the variable supercharging mechanism, and control is performed based on the operation amount (opening of the waste gate valve 28: equivalent to the variable nozzle opening VN of the above-described embodiment). It is also possible.

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) of failure diagnosis control by one Embodiment of the control apparatus of this invention. It is a flowchart (second half) of failure diagnosis control by one embodiment of the control device of the present invention. It is a map used when determining the instruction value to a motor. It is a map used when determining the atmospheric pressure correction standard variable nozzle opening VN0. 10 is a flowchart (second half) of another example of failure diagnosis control. It is a block diagram which shows the structure of the internal combustion engine (engine) which has other embodiment of the control apparatus of this invention. It is a flowchart of failure diagnosis control by other embodiment of the control apparatus of this invention.

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 DESCRIPTION OF SYMBOLS ... Turbocharger (downstream supercharger), 11a ... Variable nozzle (variable supercharging mechanism), 13 ... Throttle valve, 14 ... Accelerator pedal, 15 ... Accelerator position sensor, 16 ... ECU (Deviation degree acquisition means: Failure judgment means) : Target intake pressure calculation means: restriction means: restriction relaxation means: drive prohibition means), 19 ... pressure sensor (pressure detection means), 21 ... controller, 24 ... intake side bypass, 25 ... valve (open / close valve), 26 ... Crank position sensor, 27 ... exhaust side bypass passage, 28 ... valve, 29,30 ... supercharger (electric supercharging means), 29a, 30a ... motor ( Motivation).

Claims (1)

A supercharger disposed on an intake passage of an internal combustion engine mounted on a vehicle, an electric motor that electrically drives the supercharger, and both ends connected to the intake passage so as to bypass the supercharger Electric supercharging means having a bypass passage and an on-off valve for opening and closing the bypass passage;
Pressure detecting means for detecting the pressure in the intake passage on the downstream side of the supercharger;
Based on the pressure value detected by the pressure detection means, a divergence degree acquisition means for acquiring the degree of divergence from the supercharged state of the supercharged state by the electric supercharging means, and
Failure judgment means to judge the degree of deviation obtained by the deviation degree acquisition unit when the supercharging insufficient side is a predetermined degree of deviation or more, the on-off valve is faulty,
A downstream supercharger disposed on the intake passage downstream of the supercharger, a target intake pressure calculating means for calculating a target intake pressure of the internal combustion engine, and a pressure detected by the pressure detecting means A variable supercharging mechanism that changes a supercharging state by the downstream supercharger based on a deviation between a value and a target intake pressure calculated by the target intake pressure calculating means;
The pressure detection means detects the pressure in the intake passage on the downstream side of the downstream supercharger;
The failure determination means determines that the on-off valve has failed when the control amount associated with the supercharging state change by the variable supercharging mechanism is equal to or greater than a predetermined control amount, and further, by the variable supercharging mechanism When the control amount associated with the supercharging state change to the supercharging increasing side is equal to or greater than the predetermined amount and the engine speed is in the high speed range, it is determined that the on-off valve is stuck in the closed state. When the control amount accompanying the supercharging state change to the supercharging increasing side by the variable supercharging mechanism is a predetermined amount or more and the engine speed is in the low speed range, the on-off valve is in the open state. Judge that it is stuck,
By limiting means for limiting the control amount by the variable supercharging mechanism to a predetermined range, and by the limiting means when the failure determining means determines that the on-off valve is stuck in the closed state or the open state A control device for an internal combustion engine having a supercharger with an electric motor , further comprising restriction relaxation means for relaxing the restriction .

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