JP2011007115A - Throttle control device of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve accuracy in abnormality diagnosis of a biasing means for biasing a throttle valve.SOLUTION: A throttle driving mechanism 16 includes a throttle motor 17 for opening and closing a throttle valve 15, and an opener spring 34 and a return spring 35 for biasing the throttle valve in an opening direction and a closing direction. An ECU 30 executes feedback control for converging a throttle opening to a target throttle opening. For abnormality diagnosis of the opener spring 34 and the return spring 35, the throttle valve 15 is controlled to have the target opening by motor energization against tensile force of the springs 34, 35, then, while the throttle valve 15 is controlled to have the target opening, motor energization cutoff and re-energization are repeatedly executed in the ECU 30. Then, the abnormality of the springs 34, 35 is diagnosed based on a motor driving current during the motor energization cutoff and the re-energization.

Description

  The present invention relates to a throttle control device for an internal combustion engine that performs an abnormality diagnosis on an electronically controlled throttle drive mechanism.

  2. Description of the Related Art Conventionally, an electronic throttle control system that includes a motor that opens and closes a throttle valve and a valve spring that biases the throttle valve in an opening direction or a closing direction has been embodied. For example, Patent Document 1 is known. That is, in Patent Document 1, after driving the motor so that the throttle valve opening position is equal to or greater than the predetermined opening position, the power supply to the motor is shut off, and the throttle opening sensor of the throttle opening sensor after a predetermined time elapses from the cutoff time. When the output value is equal to or greater than a predetermined determination value, it is determined that the return spring is broken. Thereby, the erroneous determination of the breakage failure of the return spring of the throttle valve is prevented, and the breakage of the return spring is detected.

JP 2004-225538 A

  When the power supply of the motor is shut off from the state where the throttle valve is at a predetermined opening as described above and the throttle valve is self-returned by the urging force of the valve spring, in the situation where the urging force of the valve spring is not sufficient, Even if the valve spring is normal, the throttle valve does not return to its original state, and as a result, the accuracy of abnormality diagnosis may be reduced. In other words, the urging force of the valve spring changes according to the opening difference with respect to the initial position (the opening position of the motor de-energized state), and when the opening difference is small, the urging force of the valve spring is weakened. May not return to the initial position. Also, for example, if deposits (deposits) are attached to the inner wall of the intake pipe, there is a risk that the throttle valve will stick or the sliding resistance will increase. Without returning to the return position, the accuracy of abnormality diagnosis is reduced.

  SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has as its main object to provide a throttle control device for an internal combustion engine that can increase the abnormality diagnosis accuracy of the urging means that urges the throttle valve. To do.

  Hereinafter, means for solving the above-described problems and the effects thereof will be described.

  The throttle control device for an internal combustion engine according to the present invention is applied to a throttle drive mechanism having a drive means for opening and closing a throttle valve of the internal combustion engine and an urging means for urging the throttle valve in at least one of the opening and closing directions. Feedback control is performed to converge the valve opening to the target opening. In the first aspect of the invention, the first control means controls the throttle valve to a predetermined target opening degree by the driving means against the urging force of the urging means, and the first control means. Second control means for repeatedly executing drive stop and redrive of the drive means while the throttle valve is controlled to a predetermined target opening, and drive stop and redrive of the drive means by the second control means An abnormality diagnosing unit that acquires an amount of change in the opening of the throttle valve accompanying the above or a correlation amount correlated therewith as an abnormality diagnosing parameter and diagnoses an abnormality of the urging unit based on the abnormality diagnosing parameter.

  In the above configuration, when the driving valve is repeatedly stopped and re-driven while the throttle valve is controlled to the predetermined target opening against the urging force of the urging means, the urging means is normal. If there is, the increase / decrease of the opening degree of the throttle valve is repeated, and the opening degree change amount or the correlation amount thereof (for example, the feedback control amount based on the opening degree deviation) is calculated as a normal value. Therefore, it can be determined that the biasing means is normal. On the other hand, if the urging means is abnormal, the throttle valve opening does not increase or decrease, so it can be determined that the urging means is abnormal based on the amount of change in the opening or the correlation amount. It becomes.

  In such a case, the opening change of the throttle valve due to the drive stop and re-drive of the drive means occurs near a predetermined target opening, that is, in a state where the biasing force of the biasing means is relatively large. It is possible to make a clear difference in the abnormality diagnosis parameter (the amount of change in the opening degree and the correlation amount) between the abnormality and the abnormality. Therefore, the accuracy of abnormality diagnosis can be increased. In addition, since the driving means is repeatedly stopped and re-driven while a sufficient urging force is secured, the change in the opening of the throttle valve may be caused by a factor that is different from the abnormality of the urging means, such as sticking of the throttle valve. Even if it becomes difficult to occur, it is possible to prompt the change in the original throttle valve opening while eliminating the factor. As a result, it is possible to improve the abnormality diagnosis accuracy of the throttle valve urging means.

  When a motor is used as the driving means, the motor energization is repeatedly cut off and re-energized while the throttle valve is controlled to a predetermined target opening (second control means). An abnormality diagnosis of the urging unit is preferably performed based on the abnormality diagnosis unit.

  In the second aspect of the present invention, an integrated value of the abnormality diagnosis parameter acquired every time the driving unit is re-driven is calculated, and an abnormality of the urging unit is determined based on the calculated integrated value of the abnormality diagnosis parameter. Diagnose. Thereby, the accuracy of the abnormality diagnosis can be improved as compared with the case where the abnormality diagnosis is performed with one abnormality diagnosis parameter after the driving unit is re-driven.

  According to a third aspect of the present invention, after the driving means is re-driven by the second control means, a feedback control amount is calculated based on the opening deviation of the throttle valve at that time as the abnormality diagnosis parameter, and the calculated feedback An abnormality of the biasing means may be diagnosed based on the control amount.

  According to a fourth aspect of the present invention, the drive stop time for each time of the drive means can be detected, and the change in the opening of the throttle valve accompanying the drive stop of the drive means can be detected and the biasing means is attached. The time width is in the middle of the opening change of the throttle valve due to the force.

  According to this configuration, the drive means is stopped based on the drive stop time described above, so that a change in the opening of the throttle valve can be reliably detected during subsequent re-drive, and an abnormality diagnosis parameter can be acquired appropriately. . In addition, since the throttle valve opening change is in progress at the start of re-driving, the throttle valve opening change is near the target opening as compared to the configuration in which the drive is stopped until the opening change is completed. It can be done.

  In the fifth aspect of the present invention, the switching cycle between the driving stop and the re-driving of the driving unit is set as a cycle at which the throttle valve can be changed to the target opening every time the driving unit is re-driven. Yes.

  According to this configuration, the throttle valve changes to the target opening every time the driving means is driven again when the driving means is stopped and re-driven. Can be done near degrees.

  As an urging means for urging the throttle valve in either of the opening and closing directions, an opener spring that urges the throttle valve toward the valve opening side to maintain the throttle valve at a predetermined intermediate opening degree (Claim 6), A return spring (claim 7) for returning the valve to the valve closing side can be applied. In this case, according to the abnormality diagnosis method described above, the abnormality of the opener spring and the return spring can be suitably diagnosed.

  In particular, the intermediate opening is a throttle valve opening that secures an intake air amount for realizing retreat travel when a vehicle failure occurs, and is generally near the fully closed position (for example, +5 to +5 from the fully closed position). 10 deg). Therefore, in the abnormality diagnosis of the opener spring, the amount of change in the opening of the throttle valve toward the valve closing side is inevitably small, and a sufficient urging force cannot be secured. In this respect, by performing the abnormality diagnosis as described above, the accuracy of the abnormality diagnosis can be improved even when the amount of change in the opening of the throttle valve to the valve closing side is limited in the abnormality diagnosis of the opener spring.

The block diagram which shows the outline of the engine control system in embodiment of invention. The schematic diagram which shows the structure of a throttle drive mechanism. The flowchart which shows the process sequence of an abnormality diagnosis main routine. The flowchart which shows the process sequence of the abnormality diagnosis about an opener spring. The flowchart which shows the process sequence of the abnormality diagnosis about a return spring. The time chart for demonstrating the specific aspect of the abnormality diagnosis process of an opener spring and a return spring. The time chart for demonstrating the specific aspect of the abnormality diagnosis process of an opener spring and a return spring.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, an embodiment of the invention will be described with reference to the drawings. The present embodiment is embodied as a vehicle engine control system having an electronic throttle control function, and the throttle valve is electronically controlled in accordance with the driver's accelerator operation.

  First, a schematic configuration of the entire engine control system will be described with reference to FIG. An air cleaner 13 is provided at the most upstream portion of the intake pipe 12 of the engine 11 that is an internal combustion engine, and an air flow meter 14 for detecting the intake air amount is provided downstream of the air cleaner 13. A throttle valve 15 that is an intake throttle valve is provided on the downstream side of the air flow meter 14. The throttle valve 15 is opened and closed by a throttle drive mechanism 16 having a throttle motor 17 as a drive means, and the throttle opening is adjusted by driving the throttle motor 17. The throttle drive mechanism 16 is provided with a throttle opening sensor 18 (throttle opening detecting means) for detecting the throttle opening.

  An intake manifold 19 that introduces air into each cylinder of the engine 11 is provided on the downstream side of the throttle valve 15, and a fuel injection valve 21 that injects fuel for each cylinder in the vicinity of the intake port of the intake manifold 19 of each cylinder. It is attached. An ignition plug (not shown) is attached to the cylinder head of the engine 11 for each cylinder, and the air-fuel mixture in the cylinder is ignited by the spark discharge of each ignition plug and used for combustion. The exhaust gas after combustion is discharged through the exhaust pipe 22.

  In this system, the crank angle sensor 24 that outputs a crank angle signal (pulse signal) every time the crankshaft rotates a predetermined crank angle, and the accelerator sensor that detects the amount of depression of the accelerator pedal 25 (accelerator operation amount) by the driver. 26 is provided. Based on the crank angle signal from the crank angle sensor 24, the crank angle position and the engine speed are detected each time.

  Detection signals from the various sensors described above are input to an electronic control unit (hereinafter referred to as ECU) 30. The ECU 30 is configured mainly by a microcomputer including a CPU, a ROM, a RAM, and the like, and executes various engine control programs stored in the ROM, thereby causing the fuel injection amount of the fuel injection valve 21 based on the engine operating state. Further, the ignition timing of the spark plug, the opening degree of the throttle valve 15 and the like are controlled.

  Next, the configuration of the throttle drive mechanism 16 will be described with reference to the schematic diagram of FIG. 2A shows a state when the motor is not energized (initial state), FIG. 2B shows a state where the motor is energized and the throttle is driven to the open side, and FIG. 2C shows a state when the motor is energized and is closed. The throttle drive state to the side is shown, respectively.

  In FIG. 2, a throttle motor 17 is connected to a rotating shaft 15a of the throttle valve 15 via a speed reduction mechanism 31, and when the throttle motor 17 is energized, the throttle valve 15 is either open or closed. Driven by. A valve lever 32 is connected and fixed to the rotating shaft 15a, and an opener 33 is provided on the open side of the valve lever 32 so as to engage with the valve lever 32. The valve lever 32 is urged by the opener spring 34 in the opening direction of the throttle valve 15 (upward in FIG. 2), and the opener 33 is urged by the return spring 35 in the closing direction of the throttle valve 15 (downward in FIG. 2). ing. In particular, the opener spring 34 is provided between the valve lever 32 and the opener 33, and the valve lever 32 is pulled and biased against the opener 33 by the opener spring 34. The opener 33 includes a spring connecting portion 33a to which the end portions of the opener spring 34 and the return spring 35 are connected, and an engaging portion 33b that engages the opener 33 while ensuring a separation distance from the valve lever 32. ing.

  A throttle fully closed stopper 36 for defining the fully closed position of the throttle valve 15 is provided on the closed side of the valve lever 32, and a throttle opening (when the throttle motor 17 is not energized) is provided on the closed side of the opener 33. An opener stopper 37 for defining an intermediate opening) is provided.

  In the above configuration, when the throttle motor 17 is not energized, the opener 33 is held in contact with the opener stopper 37 by the tensile force of the return spring 35 as shown in FIG. In this state, the engaging portion 33b of the opener 33 is engaged with the valve lever 32, the valve lever 32 is held at a position where the opener 33 is regulated by the opener stopper 37, and the throttle opening is at a predetermined intermediate position. The opening is maintained. The intermediate opening is set to a throttle opening that can secure an intake air amount during retreat travel, and is, for example, 5 to 10 deg.

  When the throttle motor 17 is energized, the throttle opening is adjusted by rotating the throttle motor 17 in either the forward or reverse direction in accordance with the operation of the accelerator pedal 25. At this time, the throttle motor 17 is rotated in the forward direction (forward rotation) at the time of opening driving for increasing the throttle opening. 2B, the valve lever 32 moves in the opening direction against the pulling force of the return spring 35 together with the opener 33, and the throttle valve 15 is driven in the opening direction.

  Further, at the time of the closing drive for decreasing the throttle opening, the throttle motor 17 is rotated in the reverse direction (reverse rotation). As a result, as shown in FIG. 2C, the valve lever 32 moves in the closing direction against the pulling force of the opener spring 34, and the throttle valve 15 is driven in the closing direction. When the throttle valve 15 is closed to the fully closed position (for example, 0 deg), the valve lever 32 is brought into contact with the throttle fully closed stopper 36 to prevent further rotation.

  Here, when the electronic throttle control system is abnormal, the power supply to the throttle motor 17 is kept off (OFF). In this state, as described in FIG. 2A, the opener 33 is held in contact with the opener stopper 37 by the tensile force of the return spring 35, and the valve lever 32 is held by the tensile force of the opener spring 34. The throttle opening is maintained at a state in contact with the opener 33, and the throttle opening becomes a predetermined intermediate opening (for example, 5 to 10 degrees). As a result, the amount of intake air for retreat travel (limp home) is secured, and retreat travel is possible when an abnormality occurs.

  The opener spring 34 biases the valve lever 32 to the open side so as to contact the opener 33, thereby holding the valve lever 32 at a position where the throttle opening becomes a predetermined opener opening. Acts as a spring.

  The ECU 30 executes the throttle control programs stored in the ROM, thereby calculating the target throttle opening based on the accelerator operation amount detected by the accelerator sensor 26 and the like, and detecting it by the throttle opening sensor 18. The throttle motor 17 is driven so that the actual throttle opening matches the target throttle opening, and feedback control of the throttle opening is executed.

  Further, the ECU 30 performs abnormality diagnosis on the opener spring 34 and the return spring 35 while the engine is stopped. In this case, as an abnormality diagnosis of the opener spring 34, the throttle motor 17 drives the throttle valve 15 closer to the intermediate opening degree against the pulling force of the opener spring 34, and then the energization of the throttle motor 17 is cut off. Whether or not there is an abnormality in the opener spring 34 is determined based on the opening return amount of the throttle valve 15 that accompanies this. In this case, if the opener spring 34 is normal, the throttle valve 15 returns to the intermediate opening position after the energization of the throttle motor 17 is interrupted. On the other hand, if the opener spring 34 is abnormal, the energization of the throttle motor 17 is interrupted. The throttle valve 15 does not return to the intermediate opening position. Thereby, abnormality diagnosis of the opener spring 34 becomes possible.

  As an abnormality diagnosis of the return spring 35, the throttle motor 17 is driven to the opening side from the intermediate opening degree against the tensile force of the return spring 35, and then the energization of the throttle motor 17 is cut off. The presence / absence of abnormality of the return spring 35 is determined based on the opening return amount of the throttle valve 15. In this case, if the return spring 35 is normal, the throttle valve 15 returns to the intermediate opening position after the energization of the throttle motor 17 is interrupted. On the other hand, if the return spring 35 is abnormal, the energization of the throttle motor 17 is interrupted. The throttle valve 15 does not return to the intermediate opening position. Thereby, abnormality diagnosis of the return spring 35 becomes possible.

  In this embodiment, in order to perform abnormality diagnosis of the opener spring 34 and the return spring 35 while the engine is stopped, in this embodiment, the main relay (not shown) of the power supply line is kept for a while after the ignition switch (IG switch) (not shown) is turned off. ) Is kept in the ON state, and energization to the ECU 30 is continued.

  By the way, in the above abnormality diagnosis, the throttle valve 17 is driven from the intermediate opening position to either the closed side or the open side against the tensile force of the springs 34 and 35 by energization of the throttle motor 17, and then the throttle motor 17 is turned on. When the energization is cut off and the throttle valve 15 is returned to the intermediate opening position by the tension force of the springs 34 and 35, even if the springs 34 and 35 are normal when the tension force of the springs 34 and 35 is not sufficient. It is conceivable that the throttle valve 15 does not perform the original return operation, and as a result, the accuracy of abnormality diagnosis decreases. Specifically, the urging force of the springs 34 and 35 changes according to the opening difference with respect to the intermediate opening position, and when the opening difference is small, the urging force of the springs 34 and 35 is weakened. May not return to a predetermined return position (intermediate opening position). Further, when deposits (deposits) or the like adhere to the inner wall of the intake pipe, the throttle valve 15 is fixed or the sliding resistance is increased. It will not return to the return position.

  Incidentally, as described above, when the throttle valve 15 is self-returned by the tension force of the springs 34 and 35, the throttle drive mechanism 16 has an intermediate open position because it does not return to the intermediate opening position which is the initial position. It can be said that there is an opening range (valve dead zone) in which the throttle valve 15 cannot be returned only by the tensile force of the springs 34 and 35 in a predetermined opening range around the intermediate opening including the degree position.

  Therefore, in the present embodiment, when each abnormality diagnosis of the opener spring 34 and the return spring 35 is performed, the throttle valve 15 is opened to a predetermined target opening degree by energizing the motor against the tensile force (biasing force) of the springs 34 and 35. Next, with the throttle valve 15 being controlled to a predetermined target opening, the energization interruption and re-energization of the throttle motor 17 are repeatedly performed. Then, the motor drive current accompanying the energization interruption and re-energization of the throttle motor 17 is acquired as an abnormality diagnosis parameter, and the abnormality of each spring 34, 35 is diagnosed based on the abnormality diagnosis parameter.

  3 to 5 are flowcharts showing a processing procedure for abnormality diagnosis of the throttle drive mechanism 16. 3 is a flowchart showing the processing procedure of the abnormality diagnosis main routine, FIG. 4 is a subroutine showing the processing procedure of the abnormality diagnosis for the opener spring 34, and FIG. 5 is the processing procedure of the abnormality diagnosis for the return spring 35. It is a subroutine which shows.

  First, the abnormality diagnosis main routine of FIG. 3 will be described. This process is repeatedly executed at a predetermined cycle by the ECU 30 as the IG switch is turned off.

  In the present embodiment, after the IG switch is turned off, first, the fully closed position learning is performed, and then the abnormality diagnosis of the throttle drive mechanism 16 is performed subsequently. That is, in FIG. 3, first, in step S101, it is determined whether or not learning of the fully closed position of the throttle valve 15 is completed.

  Here, the fully closed position learning is a process of learning the fully closed position of the throttle valve 15 and storing the learned value in a backup memory such as an EEPROM or a backup RAM. Specifically, the throttle motor 17 is driven until the valve lever 32 comes into contact with the throttle fully closed stopper 36 to hold the throttle valve 15 in the fully closed position, and the output value of the throttle opening sensor 18 at the held position. Is obtained as the fully closed position output value. Then, the previous learning value is updated with the fully closed position output value. As a result, variations in sensor output due to changes in the throttle motor 17 over time, output errors of the throttle opening sensor 18, and the like are eliminated.

  If the fully closed position learning is not completed, this routine is terminated as it is, and the fully closed position learning is executed in another routine (not shown). On the other hand, if the fully closed position learning is completed, the process proceeds to step S102, and it is determined whether or not the abnormality diagnosis of the opener spring 34 is completed. If the abnormality diagnosis of the opener spring 34 has not been completed, the process proceeds to step S103, and the opener spring abnormality diagnosis process of FIG. 4 described later is executed. If the abnormality diagnosis of the opener spring 34 has been completed, the process proceeds to step S104. It is determined whether or not the abnormality diagnosis of the return spring 35 has been completed. If the abnormality diagnosis of the return spring 35 has not been completed, the process proceeds to step S105, where a return spring abnormality diagnosis process shown in FIG. 5 described later is executed. If the abnormality diagnosis has been completed, this routine is immediately terminated. .

  Next, the opener spring abnormality diagnosis process will be described with reference to the flowchart of FIG. This process is a process for determining whether or not the opener spring 34 is abnormal.

  In FIG. 4, first, in step S201, a target opening degree TT1 for opener spring abnormality diagnosis is set. The target opening TT1 is a target value in the feedback control of the throttle opening. After the target opening TT1 is set, the feedback control is executed in a separate routine so that the actual throttle opening matches the target opening TT1. Is done. Here, as the target opening TT1, the throttle opening closer to the intermediate opening is set.

  Thereafter, in step S202, it is determined whether or not a predetermined time Ta has elapsed after the start of feedback control based on the target opening TT1. The predetermined time Ta may be a time sufficient for the actual throttle opening to converge to the target opening TT1 after the feedback control is started. If the predetermined time Ta has elapsed, the process proceeds to step S203. If the predetermined time Ta has not elapsed, the present process is terminated.

  In step S203, the energization interruption and re-energization of the throttle motor 17 are performed. Here, the energization interruption and re-energization of the throttle motor 17 are performed at a predetermined time interval (fixed period), and the motor is re-energized when a predetermined time has elapsed since the energization interruption, and then the predetermined time elapses. Continue to energize the motor.

  In the present embodiment, the energization cutoff time Toff for each time of the throttle motor 17 can be detected as a change in the opening degree of the throttle valve 15 due to the motor energization interruption, and the opening degree change of the throttle valve 15 due to the spring tension force is being changed. The time span is as follows. That is, the minimum time width in which the opening degree change of the throttle valve 15 can be detected is the minimum value of the energization cut-off time Toff, and is the maximum in the middle of the opening degree change of the throttle valve 15 due to the spring tension. Is a maximum value of the energization cut-off time Toff. However, the energization cut-off time Toff may be a time near the minimum value within the above time width. In addition, the motor energization interruption and re-energization switching period is a period in which the throttle valve 15 can change to the target opening degree TT1 every time the throttle motor 17 is re-energized.

  In the subsequent step S204, the motor drive current Im is read after the throttle motor 17 is re-energized. In the present embodiment, the motor current control value calculated as a control command value (feedback control amount) for feedback control in the ECU 30 is read as the motor drive current Im. At this time, an opening degree deviation (difference in actual throttle opening degree with respect to the target opening degree TT1) is generated as the throttle motor 17 is de-energized. Therefore, a motor drive current Im corresponding to the opening degree deviation is calculated. Alternatively, the actual motor drive current Im may be detected by a current detector provided in the throttle drive mechanism 16 or the like, and the detected value may be read.

  Thereafter, in step S205, a motor current integrated value Iacc that is an integrated value of the motor drive current Im is calculated. In the present embodiment, energization interruption and re-energization of the throttle motor 17 are repeatedly performed a plurality of times, and the motor drive current Im for each of the re-energizations is accumulated to calculate the motor current integrated value Iacc.

  Thereafter, in step S206, it is determined whether or not the energization interruption and re-energization of the throttle motor 17 have been performed n times (for example, twice). If it is not performed n times, the process is terminated as it is, and if it is performed n times, the process proceeds to the subsequent step S207.

  In step S207, it is determined whether or not the motor current integrated value Iacc is less than the abnormality determination value TH1. If Iacc> TH1, it is determined that the opener spring 34 is normal, and the process is terminated. If Iacc ≦ TH1, the process proceeds to step S208, where it is determined that the opener spring 34 is abnormal. In this case, the driver is notified that there is an abnormality by turning on the warning lamp or generating an alarm sound, and the abnormality information is stored in the backup memory of the ECU 30.

  Next, the return spring abnormality diagnosis process will be described with reference to the flowchart of FIG. This process is a process for determining whether or not there is an abnormality in the return spring 35. Basically, the above-described opener spring abnormality diagnosis is performed except that the target opening of the throttle valve 15 is set to the open side of the intermediate opening position. This is the same as the processing (FIG. 4). Here, the description of the overlapping processing is simplified.

  In FIG. 5, first, in step S301, a target opening degree TT2 for return spring abnormality diagnosis is set. This target opening TT2 is a target value in the feedback control of the throttle opening. After the target opening TT2 is set, feedback control is executed in a separate routine so that the actual throttle opening matches the target opening TT2. Is done. Here, as the target opening degree TT2, a throttle opening degree that is more open than the intermediate opening position is set.

  Thereafter, in step S302, after the feedback control based on the target opening degree TT2 is started, it is determined whether or not the predetermined time Tb has elapsed. If the predetermined time Tb has elapsed, the process proceeds to step S303. The predetermined time Tb may be a time sufficient for the actual throttle opening to converge to the target opening TT2 after the feedback control is started.

  In steps S303 to S305, similarly to steps S203 to S205 in FIG. 4, the energization interruption and re-energization of the throttle motor 17 (step S303), the motor drive current Im read after the throttle motor 17 is re-energized (step S304), The motor current integrated value Iacc is calculated (step S305). If it is determined that the energization interruption and re-energization of the throttle motor 17 have been performed n times (YES in step S306), the process proceeds to the subsequent step S307. In step S307, it is determined whether or not the motor current integrated value Iacc is less than the abnormality determination value TH2. If Iacc ≦ TH2, it is determined in step S308 that the return spring 35 is abnormal.

  Here, in the opener spring abnormality diagnosis process (FIG. 4) and the return spring abnormality diagnosis process (FIG. 5), the target opening setting (steps S201 and S301) is different, and the target when the intermediate opening position is used as a reference. The opening change amount ΔT1 until the opening degree TT1 and the opening change amount ΔT2 until the target opening degree TT2 are either ΔT1 = ΔT2 or ΔT1 ≠ ΔT2. In this embodiment, since the opening width to the fully open position when the intermediate opening position is used as a reference is larger than the opening width to the fully closed position, ΔT1 <ΔT2. The predetermined times Ta and Tb in steps S202 and S302 may be either Ta = Tb or Ta ≠ Tb, and the abnormality determination values TH1 and TH2 in steps S207 and S307 may be either TH1 = TH2 or TH1 ≠ TH2. It may be good.

  Next, a specific mode of the abnormality diagnosis process for the opener spring 34 and the return spring 35 will be described with reference to the time charts of FIGS. FIG. 6 shows a mode when both springs 34 and 35 are normal, and FIG. 7 shows a mode when both springs 34 and 35 are abnormal. 6 and 7, (a) shows the change in IG switch on / off, (b) shows the change in throttle opening, and (c) shows the change in motor energization on / off (energization / energization interruption). (D) shows the transition of the motor drive current Im, and (e) shows the transition of the motor current integrated value Iacc. Note that, in (b), the solid line indicates the transition of the actual throttle opening, and the alternate long and short dash line indicates the transition of the target opening. The motor drive current Im and the motor current integrated value Iacc are shown as absolute values with the positive and negative directions omitted.

  First, an embodiment in which both springs 34 and 35 are normal will be described with reference to FIG. Now, when the IG switch is turned off, the fully closed position learning is first executed, and the abnormality diagnosis process of the opener spring 34 is performed after the timing t1 when the fully closed position learning is completed. In this abnormality diagnosis process, the target opening TT1 is set closer to the closing position than the intermediate opening position at timing t1, and feedback control is performed on the target opening TT1. As a result, the actual throttle opening changes to the closing side and converges to the target opening TT1. That is, the throttle valve 15 is controlled to the target opening TT1 against the pulling force of the opener spring 34.

  Then, at the timing t2 when the predetermined time Ta has elapsed from the timing t1, the energization interruption and re-energization of the throttle motor 17 are started. Specifically, the actual throttle opening starts to return to the open side (intermediate opening position side) due to the pulling force of the opener spring 34 as the throttle motor 17 is turned off. Then, when the throttle motor 17 is energized again, the actual throttle opening again changes to the closed side. At this time, if the motor energization is interrupted and the actual throttle opening changes to the open side, a deviation occurs between the actual throttle opening and the target opening TT1. When the motor is re-energized, a motor drive current Im corresponding to the opening deviation is generated by feedback control, and the actual throttle opening again converges to the target opening TT1.

  At the time of motor energization interruption and re-energization after timing t2, the energization interruption time Toff starts the motor re-energization before the actual throttle opening returns to near the intermediate opening position (region including the dead zone) after the energization interruption. It is a time span. Further, the motor energization interruption and re-energization switching period is a period in which the actual throttle opening can converge to the target opening TT1 every time the throttle motor 17 is re-energized. That is, the energization cut-off time Toff and the re-energization time Ton are set from the viewpoint that the actual throttle opening is converged to the target opening TT1 every time re-energization is performed. Since the change rate of the opening (speed away from the target opening) is faster than the change speed of the actual throttle opening accompanying the motor re-energization (speed approaching the target opening), the energization cutoff time Toff <the re-energization time Ton (The illustration is omitted).

  By setting the energization cut-off time Toff and the re-energization time Ton as described above, the opening change of the throttle valve 15 can be performed near the target opening. Further, the change in the opening degree of the throttle valve 15 can be reliably detected during re-energization, and the motor drive current Im can be acquired appropriately.

  The energization interruption and re-energization of the throttle motor 17 are repeated a plurality of times (twice in the figure), each time a motor drive current Im is generated, and the motor current integrated value Iacc changes as shown. At timing t3, the motor current integrated value Iacc and the abnormality determination value TH1 are compared. In FIG. 6, since the opener spring 34 is normal, Iacc> TH1.

  Further, following the abnormality diagnosis process for the opener spring 34, the abnormality diagnosis process for the return spring 35 is performed. That is, at the timing t4, the target opening TT2 is set on the open side with respect to the intermediate opening position, and feedback control for the target opening TT2 is performed. As a result, the actual throttle opening changes to the open side and converges to the target opening TT2. That is, the throttle valve 15 is controlled to the target opening TT2 against the tensile force of the return spring 35.

  Then, at the timing t5 when the predetermined time Tb has elapsed from the timing t4, the energization interruption and re-energization of the throttle motor 17 are started. Specifically, the actual throttle opening starts to return to the closed side (intermediate opening position side) by the pulling force of the return spring 35 as the throttle motor 17 is de-energized. Then, when the throttle motor 17 is energized again, the actual throttle opening is changed to the open side again. At this time, when the motor energization is interrupted and the actual throttle opening changes to the closed side, a deviation occurs between the actual throttle opening and the target opening TT2. When the motor is re-energized, a motor drive current Im corresponding to the opening deviation is generated by feedback control, and the actual throttle opening converges again to the target opening TT2.

  The energization interruption and re-energization of the throttle motor 17 are repeated a plurality of times (twice in the figure), each time a motor drive current Im is generated, and the motor current integrated value Iacc changes as shown. At timing t6, the motor current integrated value Iacc and the abnormality determination value TH2 are compared. In FIG. 6, since the return spring 35 is normal, Iacc> TH2.

  Next, a mode in which both springs 34 and 35 are abnormal will be described with reference to FIG.

  In FIG. 7, feedback control for the target opening TT1 is performed at timings t11 to t14. At timing t12, the energization interruption and re-energization of the throttle motor 17 are started. At this time, since the opener spring 34 is abnormal in FIG. 7, even if the motor energization is cut off, the actual throttle opening hardly changes, and the deviation between the actual throttle opening and the target opening TT1 becomes slight. Therefore, the motor driving current Im generated when the motor is re-energized is also small. In this case, at timing t13, since the motor current integrated value Iacc falls below the abnormality determination value TH1, it is determined that the opener spring 34 is abnormal.

  Further, after timing t14, feedback control for the target opening TT2 is performed. At timing t15, the energization interruption and re-energization of the throttle motor 17 are started. At this time, since the return spring 35 is abnormal in FIG. 7, the actual throttle opening hardly changes even when the motor energization is cut off, and the deviation between the actual throttle opening and the target opening TT2 becomes slight. Therefore, the motor driving current Im generated when the motor is re-energized is also small. In this case, at the timing t16, since the motor current integrated value Iacc falls below the abnormality determination value TH2, it is determined that the return spring 35 is abnormal.

  According to the embodiment described in detail above, the following excellent effects can be obtained.

  When the abnormality of the opener spring 34 and the return spring 35 is diagnosed, the energization of the throttle motor 17 is cut off while the throttle valve 15 is controlled to a predetermined target opening against the tensile force (biasing force) of the springs 34 and 35. Then, re-energization was repeated and abnormality of each spring 34, 35 was diagnosed based on the motor current integrated value Iacc at that time. According to this configuration, the opening change of the throttle valve 15 due to motor energization interruption and re-energization occurs in the vicinity of a predetermined target opening, that is, in a state where the spring tension is relatively large. It becomes possible to make a clear difference in the motor current integrated value Iacc. Therefore, the accuracy of abnormality diagnosis can be increased.

  Further, since the motor energization interruption and re-energization are repeatedly performed in a state where a sufficient spring tension force is ensured, the throttle valve 15 is caused by factors different from the abnormality of the springs 34 and 35, such as the fixing of the throttle valve 15 and the like. Even if the change in the opening is less likely to occur, the original change in the opening of the throttle valve 15 can be promoted while eliminating the cause. As a result, the abnormality diagnosis accuracy for each of the springs 34 and 35 can be increased.

  In particular, since the intermediate opening set for the vehicle retreat travel is set near the fully closed position (+5 to 10 deg), in the abnormality diagnosis of the opener spring 34, the throttle valve 15 is opened to the closed side. There is a concern that the degree of change of the degree is inevitably small, and a sufficient spring tension cannot be secured. Also, if the target opening (target opening TT1) at the time of abnormality diagnosis is set near the fully closed position, the throttle valve may stick due to deposits (deposits) adhering to the inner wall of the intake pipe, and the spring tensile force is reduced. It is conceivable that the original return operation of the throttle valve 15 cannot be obtained simply by making it act. In this regard, by performing the abnormality diagnosis as described above, the accuracy of the abnormality diagnosis can be improved even if the amount of change in the opening of the throttle valve 15 toward the valve closing side is limited in the abnormality diagnosis of the opener spring 34.

  The motor drive current Im is acquired every time the motor is re-energized, and the abnormality diagnosis is performed based on the motor current integrated value Iacc that is an integrated value of the motor drive current Im. The accuracy of the abnormality diagnosis can be increased as compared with the case where the abnormality diagnosis is performed.

  The energization cut-off time for each time of the throttle motor 17 is a time width that can detect the change in the opening of the throttle valve 15 due to the motor turn-off and is in the middle of the change in the opening of the throttle valve 15 due to the spring tension. . According to this configuration, when the energization of the throttle motor 17 is interrupted during the above-described energization interruption time, the change in the opening of the throttle valve 15 can be reliably detected during subsequent energization, and the motor drive current Im is appropriately acquired. it can. Also, since the opening of the throttle valve 15 is in the middle of reopening at the start of re-energization, the opening change of the throttle valve 15 is changed near the target opening as compared to the configuration in which the power supply is cut off until the opening change is completed. It can be done.

  The switching cycle of motor energization interruption and re-energization was set to a cycle that allows the throttle valve 15 to change to the target opening (target opening TT1, TT2) each time the throttle motor 17 is re-energized. According to this configuration, when the motor energization is interrupted and re-energized, the throttle valve 15 changes to the target opening every time the motor is re-energized. Can be done.

(Other embodiments)
The present invention is not limited to the description of the above embodiment, and may be implemented as follows, for example.

  In the above embodiment, the motor drive current Im is acquired as the abnormality diagnosis parameter when the motor is re-energized, and the abnormality diagnosis is performed based on the motor current integrated value Iacc that is an integrated value of the motor drive current Im. Change this. For example, an abnormality diagnosis may be performed based on the motor drive current Im.

  Both the motor drive current Im and the motor current integrated value Iacc described above are correlation amounts that correlate with the amount of change in the throttle opening caused by motor energization interruption and re-energization. Although the configuration for performing the diagnosis has been described, it is also possible to perform an abnormality diagnosis based on the throttle opening change amount itself instead. In this case, since the amount of change in the throttle opening when the motor power is cut off is the amount of change from the target opening, an abnormality diagnosis is performed based on the opening deviation of the throttle valve (difference from the target opening). I agree.

  In the above embodiment, the abnormality diagnosis of the opener spring 34 and the abnormality diagnosis of the return spring 35 are continuously performed after the engine is stopped. However, only one of them may be performed after the engine is stopped.

  The motor energization interruption and re-energization switching period (energization interruption time Toff, re-energization time Ton) may be variably set according to each target opening. For example, as the target opening degree is larger (that is, the opening degree change amount with respect to the initial position is larger), the motor energization interruption / re-energization switching period is increased.

  The motor energization interruption / re-energization switching period (the energization interruption time Toff, the re-energization time Ton) may be changed with the elapse of time within the period in which the motor energization interruption and re-energization are repeatedly performed. For example, the switching cycle is increased or decreased with time.

  ・ When an abnormality is diagnosed, the motor energization interruption and re-energization as described above are repeated only when the amount of change in opening according to the target opening of the throttle valve (in other words, the opening difference with respect to the initial position) is less than a predetermined value. You may make it implement.

  In the above embodiment, the opener spring 34 that urges the throttle valve toward the valve opening side and the return spring 35 that urges the throttle valve toward the valve closing side are both provided as the throttle drive mechanism. It may be configured to have only one of an urging means for urging to the side and an urging means for urging to the valve closing side. In addition to the motor, it is also possible to use a pressure type actuator that operates by hydraulic pressure or pneumatic pressure as the driving means.

  DESCRIPTION OF SYMBOLS 10 ... Engine (internal combustion engine), 15 ... Throttle valve, 16 ... Throttle drive mechanism, 17 ... Throttle motor (drive means), 30 ... ECU (1st control means, 2nd control means, abnormality diagnosis means), 34 ... Opener Spring (biasing means), 35... Return spring (biasing means).

Claims (7)

Applied to a throttle drive mechanism having drive means for opening and closing a throttle valve of an internal combustion engine and biasing means for biasing the throttle valve in at least one of opening and closing directions;
In a throttle control device for an internal combustion engine that performs feedback control to converge the opening of the throttle valve to a target opening,
First control means for controlling the throttle valve to a predetermined target opening by the driving means against the urging force of the urging means;
Second control means for repeatedly stopping and re-driving the drive means in a state where the throttle valve is controlled to a predetermined target opening by the first control means;
The amount of change in the opening of the throttle valve or the amount of correlation correlated therewith is acquired as an abnormality diagnosis parameter when the second control unit is driven and stopped by the driving unit, and the biasing unit is based on the abnormality diagnosis parameter. An abnormality diagnosis means for diagnosing abnormalities of
A throttle control device for an internal combustion engine, comprising: Means for calculating an integrated value of the abnormality diagnosis parameter acquired each time the driving means is re-driven;
2. The throttle control device for an internal combustion engine according to claim 1, wherein the abnormality diagnosis unit diagnoses abnormality of the biasing unit based on an integrated value of the abnormality diagnosis parameter. A means for calculating a feedback control amount based on an opening deviation of the throttle valve at that time as the abnormality diagnosis parameter after the driving means is re-driven by the second control means;
The throttle control device for an internal combustion engine according to claim 1 or 2, wherein the abnormality diagnosis means diagnoses an abnormality of the urging means based on the calculated feedback control amount.   The second control means can detect the drive stop time for each driving means by detecting the change in the opening degree of the throttle valve accompanying the driving stop of the driving means, and by the biasing force of the biasing means. The throttle control device for an internal combustion engine according to any one of claims 1 to 3, wherein the time width is a time period during which the opening degree of the throttle valve is changing.   The second control means sets the driving stoppage and redrive switching period of the driving means to a period in which the throttle valve can be changed to the target opening every time the driving means is redriven. Item 5. The throttle control device for an internal combustion engine according to any one of Items 1 to 4. The biasing means is an opener spring that biases the throttle valve toward the valve opening side in order to maintain the throttle valve at a predetermined intermediate opening.
The first control means drives the throttle valve to the valve closing side by the driving means against the urging force of the opener spring,
The throttle control device for an internal combustion engine according to any one of claims 1 to 5, wherein the abnormality diagnosis means diagnoses an abnormality of the opener spring. The urging means is a return spring for returning the throttle valve to the valve closing side,
The first control means drives the throttle valve to the valve opening side by the driving means against the urging force of the return spring,
The throttle control device for an internal combustion engine according to any one of claims 1 to 6, wherein the abnormality diagnosis means diagnoses an abnormality of the return spring.

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