JP2010090904A - Secondary air supply device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a secondary air supply device allowing the malfunction of structural components to be accurately determined and to detect an operating failure. <P>SOLUTION: The secondary air supply device is provided for supplying air to the upstream side of an exhaust emission control device in an engine exhaust pipe so that burnable materials in exhaust gas are secondarily burnt to purify the exhaust gas. It finds pressure behavior patterns (patterns 1-4) from a time average value for a pressure value and a pressure fluctuation value detected by a pressure sensor arranged between an air pump and an on-off valve and determines the operating conditions of the air pump and the on-off valve on the basis of variations of the pressure behavior patterns during controlling the supply and stop of secondary air. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a secondary air supply device that supplies secondary air to an upstream side of an exhaust purification device that is disposed in an exhaust system of an internal combustion engine, and more particularly to a secondary air supply device that can detect abnormality of its components. .

  As an exhaust gas purification device for an internal combustion engine, a device is known in which a three-way catalyst is disposed in an exhaust system to purify the exhaust gas by reducing CO, HC, and NOx components. Further, by pumping air from the air pump to a secondary air supply passage having an on-off valve connected to the exhaust pipe, the secondary air is supplied into the exhaust pipe to increase the oxygen concentration, and HC in the exhaust gas, A technique for promoting the purification of exhaust gas by oxidizing CO is known.

  In such a secondary air supply device, if any of the above components such as an air pump or an on-off valve occurs, the exhaust gas purification efficiency is reduced and the emission deteriorates. Therefore, it is necessary to determine the abnormality early. . Therefore, techniques disclosed in Patent Document 1 and Patent Document 2 are known as techniques for detecting this type of abnormality.

  In the former, a pressure sensor is disposed between the air pump and the on-off valve in the secondary air supply passage, and an abnormality of the secondary air supply device is detected based on the detected pressure value. In the latter, a pressure sensor is disposed in the secondary air supply passage, and an abnormality of the secondary air supply device is detected based on the difference between the detected maximum value and the minimum value of the pressure pulsation.

Japanese Patent Laid-Open No. 9-21312 JP-A-9-125945

  However, according to these techniques, an abnormality in the secondary air supply device itself can be detected, but it is difficult to accurately determine which of the component parts is abnormal. Furthermore, even when the component does not function normally, the abnormality cannot be detected when the pressure value and the pressure pulsation are malfunctioning in which the normal value is indicated.

  Therefore, an object of the present invention is to provide a secondary air supply device that can accurately determine an abnormality of a component and can detect a malfunction.

  In order to solve the above problems, a secondary air supply device according to the present invention includes a secondary air supply passage for supplying secondary air upstream of an exhaust purification device for an exhaust system of an internal combustion engine, and a secondary air supply passage. A secondary air supply device comprising an opening / closing means for opening and closing, and a check valve disposed downstream of the opening / closing means, a pressure sensor disposed on the secondary air supply passage, and a pressure detected by the pressure sensor The apparatus further includes an abnormality detection unit that detects an abnormality of the component based on the time average value and the pressure fluctuation value.

  According to the present invention, by checking the pressure value and the pressure fluctuation value with the pressure sensor, the failure mode of each component can be determined in more detail than before in accordance with the combination.

  It is preferable that the abnormality detection unit detects a failure mode of each component from a combination of pressure behavior patterns during secondary air supply control and supply stop control. A more detailed determination can be made by using a combination of pressure behavior patterns during supply control and stop control.

  It is preferable that an air pump is disposed upstream of the opening / closing means, and the pressure sensor is disposed at an intermediate position between the air pump and the opening / closing means. By disposing the air pump at an intermediate position between the air pump and the opening / closing means in this manner, it becomes easy to individually detect the abnormality of the opening / closing means and the abnormality of the air pump.

  When an absolute pressure sensor is used as the pressure sensor, the abnormality detection unit can grasp the relative pressure when the abnormality is detected and store the detected value immediately before the engine start of the pressure sensor as the atmospheric pressure, and when the secondary supply system is stopped. This pressure sensor can be used as an atmospheric pressure sensor and is preferable.

  It is preferable that the abnormality detection unit further has a function of monitoring the flow rate of the air pump from the output value of the pressure sensor. When the secondary air supply device on the downstream side of the air pump is normal, the discharge flow rate of the air pump and the pressure value are maintained in a predetermined relationship, so that the discharge flow rate can be estimated from the pressure value.

  The abnormality detection unit may detect clogging of the secondary air supply passage by driving the air pump at the time of opening / closing control of the opening / closing means and detecting the discharge pressure of the air pump. If the secondary air supply passage is clogged, when the secondary air is supplied, the pressure behavior may show the same behavior as when the discharge flow rate is not secured due to an abnormality of the air pump. According to the present invention, it is possible to simultaneously determine abnormality of the air pump and clogging of the secondary air supply passage by detecting a decrease in the discharge pressure by driving the air pump during the closing control.

  An air-fuel ratio sensor disposed in the exhaust system may be further provided, and the output thereof may be further input to the abnormality detection unit. By checking the air-fuel ratio in the exhaust system, it can be determined whether or not the secondary air supply is normally performed.

  Here, whether the abnormality determination is based on the difference between the target air-fuel ratio according to the intake air amount and the actual air-fuel ratio, or based on the difference between the expected air-fuel ratio according to the engine coolant temperature and the actual air-fuel ratio. It is preferable to base the difference in air-fuel ratio on the secondary air supply control and on the stop control.

  Although the secondary air supply control is performed at the time of cold start, it takes a certain time after the start until the air-fuel ratio sensor is activated. Therefore, by forcibly turning off the secondary air supply control temporarily, It is preferable to determine the activation of the fuel ratio sensor.

  Further, the pressure sensor may be disposed between the opening / closing means and the check valve. In this case, it is possible to detect an abnormality of the check valve based on the pressure value and the pressure fluctuation value detected by the pressure sensor when the opening / closing means is in the closed control state.

  According to the present invention, unlike the conventional case, it is possible to accurately determine whether or not there is a malfunction such as an abnormality or malfunction of an air pump, an on-off valve, a check valve, piping, etc., which are components constituting the secondary air supply device. can do. Further, depending on the malfunction, it is also possible to make a determination before the secondary air supply control and at an early stage during the control.

It is the schematic which shows the secondary air supply apparatus which concerns on this invention. It is a graph which shows the pressure behavior pattern in A point of FIG. It is a graph which shows the pressure behavior pattern in the B point of FIG. It is a main flowchart of the 1st abnormality detection process routine in the apparatus of FIG. 5 is a flowchart for explaining in detail a part of the processing of FIG. 4. 5 is a flowchart for explaining another part of the process of FIG. 4 in detail. 6 is a flowchart for explaining in detail another part of the processing of FIG. 4. It is a figure which shows the relationship between an air pump flow volume and discharge pressure. It is a flowchart in the case of performing the clogging determination process of piping in addition to the process of FIG. It is a figure which shows the secondary air supply apparatus which performs a 2nd abnormality detection process routine. It is a main flowchart of the 2nd abnormality detection process routine performed in the air supply system of FIG. It is a flowchart which shows a part of FIG. 11 in detail. It is a figure which shows the secondary air supply apparatus which performs a 3rd abnormality detection process routine. It is a main flowchart of the 3rd abnormality detection process routine performed in the air supply system of FIG. It is a flowchart which shows a part of FIG. 14 in detail. It is a main flowchart of a 4th abnormality detection process routine. It is a flowchart which shows in detail the A / F sensor activation determination process which is a part of FIG. It is a graph which shows the relationship between an intake air amount, a secondary A / F value, and an A / F fluctuation value, respectively. It is a main flowchart of a 5th abnormality detection process routine. It is a graph which shows the relationship between engine cooling water temperature, normal engine speed, the expected increase A / F value by secondary air supply, and the expected A / F value at the time of secondary air non-supply, respectively.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described in detail with reference to the accompanying drawings. In order to facilitate the understanding of the description, the same reference numerals are given to the same components in the drawings as much as possible, and duplicate descriptions are omitted.

FIG. 1 is a schematic diagram showing a configuration of a secondary air supply device according to the present invention. The secondary air supply device 1 is attached to a multi-cylinder gasoline engine (hereinafter simply referred to as an engine) 2 that is an internal combustion engine. Here, an intake pipe 20 and an exhaust pipe 21 are attached to the engine 2, and a throttle 24 is disposed in the intake pipe 20 and connected to an intake filter 25. An air flow meter 26 for measuring an air amount (primary air amount) is disposed between the intake filter 25 and the throttle 24. On the other hand, an exhaust purification device 22 comprising a three-way catalyst is disposed downstream of the exhaust pipe 21, and O ₂ sensors 31, 32 for detecting the oxygen concentration in the exhaust both upstream and downstream of the exhaust purification device. Is arranged. Instead of the O ₂ sensor, A / F sensor may also be used a linear O ₂ sensor.

The secondary air supply device 1 includes a secondary air supply passage 11 that connects a position between the intake filter 25 and the throttle 24 of the intake pipe 20 and the engine 2 and the upstream O ₂ sensor 31 of the exhaust pipe 21. An electric motor driven air pump (AP) 12, an air switching valve (ASV) 13, and a reed valve (RV) 14 as a check valve are arranged on the secondary air supply passage 11 from the intake pipe 20 side. Is done. And the pressure sensor 15 is arrange | positioned between AP12 and ASV13. A pipe 16 extending from the downstream side of the throttle 24 of the intake pipe 20 is connected to the ASV 13, and an electromagnetic valve 17 is further disposed on the pipe 16.

The control device 10 that controls the operation of the secondary air supply device 1 is connected to the engine ECU 23 that controls the engine so as to exchange information with each other, and output signals from the pressure sensor 15 and the O ₂ sensors 31 and 32. Is controlled, and the motor drive of the AP 12 and the opening and closing of the electromagnetic valve 17 are controlled. Note that the control device 10 may form part of the engine ECU 23.

  The secondary air supply device 1 has a high fuel concentration mainly during cold start, a small air-fuel ratio (A / F), and the exhaust purification device 22 has not sufficiently raised its function and has a sufficient function. When the control device 10 opens the electromagnetic valve 17 in a state where it is difficult to be exhibited, the negative pressure in the intake pipe 20 is guided to the ASV 13 to control the opening of the ASV 13, and the air pump 12 is driven to drive the air filter 25. A part of the air that has passed through the exhaust gas is introduced into the exhaust pipe 21 through the secondary air supply passage 11, thereby increasing the oxygen concentration in the exhaust gas, increasing its A / F, and increasing the HC and CO in the exhaust gas. While purifying the exhaust gas by promoting secondary combustion in the exhaust pipe 21, the temperature of the three-way catalyst of the exhaust gas purification device 22 is increased by increasing the exhaust gas temperature, thereby suppressing the deterioration of emissions. In place of the combination of the ASV 13 and the electromagnetic valve 17, an electromagnetic valve can be used directly in the ASV 13 portion.

  The secondary air supply device 1 according to the present invention is characterized in that it has a function of detecting an abnormality of components, that is, the air pump 12, the ASV 13, the RV 14, and the like. Specifically, the control device 10 detects an abnormality of the component based on the pressure behavior detected by the pressure sensor 15 disposed on the secondary air supply passage 10. Hereinafter, some of the abnormality detection processing routines will be described in detail.

  First, the first abnormality detection processing routine will be described. Before specifically describing this process, the pressure behavior in the secondary air supply passage 10 will be briefly described.

これを基にして、圧力挙動パターンから逆にエアポンプ１２、ＡＳＶ１３の作動状況を推定することができる。 2 and 3 are graphs schematically showing possible patterns of pressure behavior at both points A and B in FIG. Here, it is assumed that the RV 14 is functioning normally. Here, the point A is between the air pump 12 and the ASV 13 where the pressure sensor 15 is arranged in the present embodiment, and the point B is a position between the ASV 13 and the RV 14. Table 1 summarizes the combinations of operating states of the air pump 12 and the ASV 13 and the pressure fluctuation patterns at both points in each case.

On the basis of this, the operating conditions of the air pump 12 and the ASV 13 can be estimated from the pressure behavior pattern.

  Next, the first abnormality detection routine will be described with reference to the flowcharts of FIGS. FIG. 4 is a main flowchart of this routine, and FIGS. 5 to 7 are flowcharts showing the subroutine in detail. The process shown in FIG. 4 is basically a process performed once by the control device 10 at the time of start-up, and the processes in FIGS. 5 to 7 are each called once from the main process in FIG.

  First, in step S2 shown in FIG. 4, it is checked whether or not an execution condition for secondary air supply control (abbreviated as AI in the flowchart and the following description) is satisfied. This execution condition is determined by the engine coolant temperature, the intake air temperature, the elapsed start time, the battery voltage, the load condition, etc. sent from the engine ECU 23. If the AI execution condition is not satisfied and it is determined that the AI need not be executed, a part of the process is skipped and the process proceeds to step S16 described later. In the case where the AI execution condition is not satisfied yet and the AI needs to be executed after a lapse of time, the process waits in step S2 until the condition is satisfied. When the AI execution condition is satisfied, the process proceeds to step S4.

  In step S4, it is checked whether an abnormality of the AI device has already been detected. It is preferable that a flag indicating an abnormality of the AI device, which will be described later, be reset only when the AI device is inspected and maintained without being reset even when the auxiliary power of the vehicle is turned off. If an abnormality has been detected, the process is skipped and the process proceeds to step S32 described later. Thereby, the trouble which generate | occur | produces by trying to operate AI in the state where abnormality is already known can be prevented.

  If it is determined in step S4 that an abnormality of the AI device has not been detected in advance, the process proceeds to step S6, where the air pump 12 is activated and the ASV 13 is opened. In subsequent step S8, it is checked whether or not an abnormality detection condition is satisfied. The abnormality detection condition is that the air pump 12 is in a stable state after a predetermined time has elapsed since the execution of AI, and the engine is in an idle state based on the rotational speed of the engine 2, the load and the vehicle speed condition. Indicates a condition that can be determined to be in an easy state. When the abnormality detection condition is satisfied, the process proceeds to step S10 to determine the pressure behavior pattern during supply control.

  In this supply control pressure behavior determination process (step S10), as shown in FIG. 5, first, the time change of the pressure value P detected by the pressure sensor 15 in step S100 is captured over a predetermined time. In step S102, the average value Pm is calculated. In step S104, the pulsation amplitude value Pa of the pressure value P is calculated.

  In step S106, first, the pulsation amplitude value Pa of the pressure value P is compared with a threshold value Pa0. If Pa is greater than Pa0, it is determined that the pattern is one of patterns 1 and 2 with large pulsation shown in FIG. 2, and the process proceeds to step S108. In step S108, the pressure average value Pm is compared with the threshold value P0. If Pm is greater than P0, it is determined that pattern 1 is being provided and secondary air is being supplied, and the routine proceeds to step S110 where the supply air amount Q is checked. Here, the discharge pressure of the air pump 12 and the amount of supplied air have a relationship as shown in FIG. Therefore, the supply air amount can be estimated from the discharge pressure (actually, the average value Pm of the measured values by the pressure sensor 15). If the supply air amount is less than Qx shown in FIG. 8, the fuel concentration in the exhaust gas is kept high, and the emission may be deteriorated. In step S110, it is checked whether or not the estimated supply air amount exceeds this Qx. The discharge pressure value itself may be compared with the threshold value Px.

  If it is determined in step S112 that the supply air amount is small, the process proceeds to step S114, 1 is set in the flag Xfaildown, and the process proceeds to step S120. If the supply air amount is sufficient, the process proceeds directly to step S120. In step S120, 1 is set in the flag F11, the process proceeds to step S130, 1 is set in the flag Xstep1, and this subroutine is terminated.

  If Pm is equal to or less than P0 in step S108, it is determined that the pressure behavior pattern is pattern 2, the process proceeds to step S140, 1 is set in the flag F12, and the process in step S130 is performed. This subroutine is finished.

  If Pa is equal to or less than Pa0 in step S106, it is determined that the pattern 3 or 4 has no pulsation shown in FIG. 2, and the process proceeds to step S150. In step S150, Pm and P0 are compared as in step S108. If Pm is greater than P0, it is determined that the pressure behavior pattern is pattern 3, the process proceeds to step S160, 1 is set in the flag F13, the process of step S130 is performed, and then this subroutine is terminated. To do.

  On the other hand, if Pm is less than or equal to P0 in step S150, it is determined that the pressure behavior pattern is pattern 4, the process proceeds to step S170, 1 is set in the flag F14, and the process of step S130 is performed. After that, this subroutine is finished.

  When the subroutine of FIG. 5 ends, the process proceeds to AI end condition determination in step S12 of the main flow shown in FIG. If the AI end condition is not satisfied, the process returns to step S8 and the process is repeated. On the other hand, if the abnormality detection condition is not satisfied in step S8, the pressure behavior determination in step S10 is skipped and the process proceeds to step S12. Thereby, the determination success rate and accuracy of the pressure behavior pattern determination during the execution of AI can be improved.

  If it is determined in step S12 that the AI end condition is satisfied, the process proceeds to step S14, the air pump 12 is stopped, the ASV 13 is closed, and the AI control is stopped. Then, the process proceeds to step S16, and the value of the flag Xstep1 is checked to check whether the pressure behavior determination in step S10 has been completed. When Xstep1 is other than 1, since the pressure behavior pattern at the time of supply control cannot be determined, the subsequent determination process is skipped and the process proceeds to step S32 described later. On the other hand, when Xstep1 is 1, since the determination of the pressure behavior pattern at the time of supply control has been completed, the process proceeds to the next processing step S18. In step S18, it is checked whether or not an abnormality detection condition for performing the next stop control pressure behavior determination (step S20) is satisfied. When it is satisfied, the process proceeds to step S20, and the stop behavior pressure behavior determination is performed.

  The sub-control pressure behavior determination process (step S20) shown in FIG. 6 is similar to the sub-control pressure behavior determination process subroutine shown in FIG. First, the time change of the pressure value P detected by the pressure sensor 15 in step S200 is captured over a predetermined time. Subsequently, the average value Pm is calculated (step S202) and the pulsation amplitude value Pa of the pressure value P is calculated (step S204).

  In step S206, first, Pa is compared with a threshold value Pa0. If Pa is larger than Pa0, it is determined that the pattern is one of the patterns 1 and 2 with large pulsation shown in FIG. 2, and the process proceeds to step S208. In step S208, the pressure average value Pm is compared with the threshold value P0. If Pm is greater than P0, it is determined that the pattern is 1, and the process proceeds to step S220, where 1 is set in the flag F21.

  If Pm is equal to or less than P0 in step S208, it is determined that the pressure behavior pattern is pattern 2, the process proceeds to step S240, and 1 is set in the flag F22.

  If Pa is equal to or less than Pa0 in step S206, it is determined that the pattern 3 or 4 has no pulsation shown in FIG. 2, and the process proceeds to step S250. In step S250, Pm and P0 are compared as in step S208. If Pm is greater than P0, it is determined that the pressure behavior pattern is pattern 3, the process proceeds to step S260, and 1 is set in the flag F23.

  On the other hand, if Pm is equal to or less than P0 in step S250, it is determined that the pressure behavior pattern is pattern 4, the process proceeds to step S270, and 1 is set in the flag F24.

  After the flags F21 to F24 are set, in any case, the process proceeds to step S230, the flag Xstep2 is set to 1, and this subroutine is finished.

  When the subroutine of FIG. 6 ends, the process proceeds to step S24 of the main flow shown in FIG. On the other hand, if the abnormality detection condition is not satisfied in step S18, the process proceeds to step S22 to check whether or not a predetermined time has elapsed after the AI stop. By returning to S18, re-determination is attempted for a predetermined time after the AI stops. If the predetermined time has elapsed, the process proceeds to step S24.

  In step S24, the value of the flag Xstep2 is checked to check whether or not the pressure behavior determination in step S20 has been completed. When Xstep2 is other than 1, the determination of the pressure behavior pattern at the time of stop control has not been made, so the subsequent determination process is skipped and the process proceeds to step S32 described later. On the other hand, when Xstep2 is 1, since the determination of the pressure behavior pattern during the stop control is finished, the process proceeds to the next processing step S30.

ここで、○は正常を、×は機器の異常を表す。 In step S30, the abnormality of the component is determined based on the determination results of steps S20 and S30. Table 2 summarizes the pressure behavior patterns during the supply / stop control for each combination of the normal and abnormal modes of the air pump 12 and the ASV 13.

Here, ◯ represents normality, and x represents device abnormality.

  The process flow of the abnormality determination process in step S30 shown in FIG. 7 is based on this table 2. First, in step S300, it is checked whether or not the flag F11 is 1. In the case of 1, it indicates that the pressure behavior pattern at the time of supply control is pattern 1, so that the process proceeds to step S302 and it is checked whether or not the flag F24 is 1. In the case of 1, it indicates that the pressure behavior pattern at the time of stop control is the pattern 4, so that it is clear from Table 2 that this combination is mode 1, and that both the air pump 12 and the ASV 13 are normal. Therefore, the process proceeds to step S304, where the value of the flag Xfaildown is checked to check whether or not the flow rate has dropped. When Xfaildown is not 1, since the flow rate is not reduced and the devices are all normal, the process proceeds to step S306 and 1 is set in the failure diagnosis flag XAI indicating normal. Exit the subroutine. On the other hand, when Xfaildown is 1, there is a possibility of a malfunction of the air pump 12 because of a decrease in the flow rate, and the process proceeds to step S318 to indicate that the failure diagnosis flag XAI is abnormal −1. Set and exit subroutine.

  If F24 is not 1 in step S302, it is one of modes 2, 4, and 5 in Table 2, and the process proceeds to step S310. In this step S310, it is first checked whether or not the flag F22 is 1. When F22 is not 1, that is, when the pressure behavior pattern at the time of stop control is not pattern 2, but in modes 4 and 5 which are patterns 1 and 3, since the air pump 12 is always in a failure state, The process proceeds to step S312, and 1 is set in the failure diagnosis flag XFAP of the air pump to indicate that there is always a malfunction, and the process proceeds to step S314. On the other hand, when F22 is 1, that is, when the pressure behavior pattern at the time of stop control is pattern 2, that is, in mode 2, the air pump 12 is normal, so step S312 is skipped and the process proceeds to step S314.

  In step S314, it is checked whether the flag F23 is “1”. When F23 is not 1, that is, when the pressure behavior pattern at the time of stop control is not pattern 3, but in modes 2 and 5 which are patterns 1 and 2, the ASV 13 is in an open fixed state in which the valve is always open. Then, the process proceeds to step S316, 1 is set in the ASV failure diagnosis flag XFASV to indicate that the fixing is open, the process proceeds to step S318, the failure diagnosis flag XAI is set to -1, and the subroutine is terminated. . On the other hand, when F23 is 1, that is, when the pressure behavior pattern at the time of stop control is pattern 3, that is, mode 4, the ASV 13 is normal, so step S316 is skipped and the process proceeds to step S318, and the failure diagnosis flag XAI Is set to -1 and the subroutine is terminated.

  On the other hand, if it is determined in step S300 that F11 is not 1, it indicates one of modes 3 and 6-9. In this case, the process proceeds to step S320, and it is checked whether or not the flag F12 is 1. When F12 is 1, that is, when the pressure behavior pattern at the time of supply control is pattern 2, it is either mode 7 or 8, and in any case, the air pump 12 is in an inoperative state, so the air pump failure diagnosis flag XFAP Is set to -1 indicating a non-operational failure, and the process proceeds to step S324. In this step S324, it is checked whether or not the flag F22 is 1. When F22 is 1, that is, when the pressure behavior pattern at the time of stop control is pattern 2, since it is mode 8 and the ASV 13 is in an open fixed state in which the valve is always open, the process proceeds to step S326, and the ASV failure occurs. The diagnostic flag XFASV is set to 1 indicating open fixation, the process proceeds to step S318, the failure diagnostic flag XAI is set to -1, and the subroutine is terminated. On the other hand, when F22 is not 1, it is mode 7 and the ASV 13 is normal, so step S326 is skipped and the process proceeds to step S318, −1 is set to failure diagnosis flag XAI, and the subroutine is terminated.

  On the other hand, if it is determined in step S320 that F12 is not 1, it is one of modes 3, 6, and 9. In any case, since the ASV 13 is in the normally closed closed state, which is a closed valve state, the process proceeds to step S330, and -1 indicating that the ASV failure diagnosis flag XFASV is closed closed is set. Subsequently, in step S332, it is checked whether or not the flag F13 is 1. When F13 is 1, it indicates that the pressure behavior pattern at the time of supply control is pattern 3, which is one of modes 3 and 6. In this case, the process proceeds to step S334 to check whether or not the flag F23 is 1. In the case of 1, the pressure behavior pattern at the time of stop control is also pattern 3, which means that the mode 6 is in a failure state in which the air pump 12 is always operating. Therefore, the process proceeds to step S336, and 1 is set in the failure diagnosis flag XFAP of the air pump to indicate that there is a constant operation failure. Then, the process proceeds to step S318, and the failure diagnosis flag XAI is set to −1 and the subroutine is set. Exit. On the other hand, if F23 is not 1, it is mode 3 and the air pump 12 is normal, so step S336 is skipped and the process proceeds to step S318, the failure diagnosis flag XAI is set to -1, and the subroutine is terminated. .

  If it is determined in step S332 that F13 is not 1, it indicates mode 9 and the air pump 12 is in an inoperative failure state. Therefore, the process proceeds to step S338 and -1 indicating that there is an inoperative failure is set in the failure diagnosis flag XFAP of the air pump. Then, the process proceeds to step S318, and -1 is set in the failure diagnosis flag XAI and the subroutine. Exit.

  When the subroutine of FIG. 7 ends, the process proceeds to step S32 shown in FIG. 4 to check the value of the failure diagnosis flag XAI. If the value is 1 indicating that the system is normal, step S34 is skipped and the process is terminated. On the other hand, if the value is -1 indicating that the system is abnormal or 0 indicating that the system has not been determined, the process proceeds to step S34 to operate using a display device or an alarm (not shown). Warning processing is performed to notify the user that there is an abnormality in the system or failure detection has failed, and the processing is terminated.

  According to the abnormality detection routine according to the present invention, it is possible to accurately detect which of the air pump and the ASV is malfunctioning.

  In the above description, an example is described in which the pressure behavior determination process at the time of stop control is performed after the end of AI, and then the abnormality determination process is performed. However, by temporarily stopping the temporary supply during the AI supply, By performing the pressure behavior determination, the abnormality determination may be performed while the AI supply control condition is satisfied. In this way, it is possible to perform failure diagnosis during AI control.

  Further, as shown in Table 2, since the pressure behavior pattern during the AI supply control at the time of normal equipment is limited to the pattern 1, immediately when the pressure behavior pattern during the supply control is other than the pattern 1, The AI control may be stopped and the process may proceed to pressure behavior pattern determination at the time of stop. In particular, when the pressure behavior pattern at the time of supply control is pattern 4, it is clear that the mode 9 is shown in Table 2, and therefore it is possible to omit the determination of the pressure behavior pattern at the time of stoppage. .

  Further, the position of the pressure sensor 15 is not limited to the point A, and even if it is arranged at the point B, it is possible to determine the failure mode of the device by the same method. Further, as the pressure sensor 15, an absolute pressure sensor can be used in addition to a relative pressure sensor that outputs a differential pressure from the atmospheric pressure. In this case, it is necessary that the atmospheric pressure can be detected when the operation of the secondary air system is stopped. However, in the general air pump 12, the housing and the pump rotating body are not in close contact with each other, Since the front and rear are configured to communicate with each other, the air pressure can be detected in such an air pump 12. In such a configuration, the output value before starting the engine is used as the atmospheric pressure, and the relative pressure may be calculated from the difference. As a result, the pressure sensor 15 can be used as an atmospheric pressure sensor except when a secondary air system abnormality is detected and during the supply of secondary air. However, since there is a possibility that the atmospheric pressure is estimated to be higher by the discharge pressure when the air pump 12 is constantly operating, the power, voltage, current, etc. of the air pump 12 may be checked and corrected. Further, when the ASV 13 is fixed open, exhaust pulsation by the engine 2 may be transmitted. In this case, since the average pressure is close to the atmospheric pressure, the atmospheric pressure can be detected by the averaging process.

  It is also possible to add a pipe clogging determination to the first abnormality detection routine. FIG. 9 is a flowchart showing this clogging determination processing, and insertion between step S304 and step S306 shown in FIG. 7 enables clogging determination in the first abnormality detection routine.

If it is determined in step S304 that the value of the flag Xfaildown is not 1, the air pump 12 is temporarily driven while the ASV 13 is closed (step S301), and the discharge pressure P is read by the pressure sensor 15 (step S303). Then, the measured discharge pressure P is compared with the threshold value P _Y (step S305). When P is smaller than P _Y, it indicates that a constant pressure value has been detected during AI supply control, despite the malfunction of the air pump. This indicates that since the piping downstream of the ASV 13 is clogged, a constant pressure increase was observed even though the discharge amount of the air pump 12 was not sufficient. Therefore, the process proceeds to step S307 and the flag Xjam indicating the piping state is set. While 1 indicating clogging is set, 1 indicating flow rate drop is set in the flag Xfaildown indicating the air pump flow rate, and the process proceeds to step S318. If a sufficient pressure increase is observed, the flow proceeds to step S306 on the assumption that there is no decrease in the flow rate of the air pump 12 or clogging of the piping. Thereby, abnormality of the secondary air supply apparatus including piping can be determined.

  Next, the second abnormality detection routine will be described with reference to FIGS. The secondary air supply apparatus in which this abnormality detection routine is performed differs from the secondary air supply apparatus shown in FIG. 1 in that the pressure sensor 15 is arranged at point B as shown in FIG. FIG. 11 is a main flowchart of abnormality detection processing, and FIG. 12 is a flowchart showing a subroutine of abnormality determination processing for the reed valve.

  First, in step S38, it is checked whether an AI execution condition is satisfied. This is a process equivalent to step S2 shown in FIG. When the condition is not satisfied (except when it is not satisfied. When it is not satisfied, the process waits until the condition is satisfied), the subsequent processing is skipped and the process is ended. If the condition is satisfied, the process proceeds to step S39, where it is checked whether an abnormality of the AI device has already been detected. This process is equivalent to step S4 shown in FIG. If an abnormality has been detected, the process is skipped and the process proceeds to step S57 described later. Thereby, the trouble which generate | occur | produces by trying to operate AI in the state where abnormality is already known can be prevented.

  If it is determined in step S39 that an abnormality in the AI device has not been detected in advance, the process proceeds to step S40 to perform a reed valve abnormality determination process. FIG. 12 is a flowchart showing the abnormality determination process.

First, the fluctuation of the pressure value P for a predetermined time is read (step S400), and the pressure average value Pm is calculated (step S401). Next, this Pm is compared with a threshold value P _A (P _A is a negative pressure, that is, not more than atmospheric pressure) (step S402). When negative pressure is generated, it means that at point B, the pressure pulsation in the exhaust pipe 21 generated by the engine 2 is held at the minimum pressure (negative pressure), and the RV 14 functions normally. It is determined that the process is being performed, and the process is terminated.

On the other hand, if no negative pressure is generated, the process proceeds to step S403, and a value -1 indicating abnormality is set in the flag XAI indicating the system state. Then, the fluctuation value ΔP of the pressure pulsation is calculated (step S404). Then, this ΔP is compared with the threshold value ΔP _A. If ΔP is larger than ΔP _A, it means that the RV 14 is always open and the pressure pulsation in the exhaust pipe 21 generated by the engine 2 is directly transmitted to the point B. Therefore, the process proceeds to step S407. Then, the flag XFRV indicating the failure state of the RV 14 is set to 1 indicating that it is in the open fixing state, and the process is terminated.

  On the other hand, if it is determined in step S406 that there is no pressure pulsation, it means that Pm is held at or near atmospheric pressure. In step S408, it is first checked whether Pm is near atmospheric pressure (relative pressure is near 0) or not. When Pm is not close to atmospheric pressure, that is, in a state higher than atmospheric pressure, it means that AI is operating even though it is in the stop control state, and thus represents a failure state of air pump 12. The flag XFAP is set to 1 indicating that it is always in an operating state, and the flag XFASV indicating a failure state of the ASV 13 is set to 1 indicating that it is in an open fixing state (step S409), and the process is terminated.

If Pm is near atmospheric pressure, the process proceeds to step S410, and ΔP is compared with another threshold value ΔP _C (where ΔP _C <ΔP _A ). When ΔP is larger than ΔP _C, it is determined that the ASV 13 is in an open state and pulsation on the intake side is transmitted, and a flag XFASV indicating a failure state of the ASV 13 is set to 1 indicating that it is in an open fixed state. Set (step S412) and the process is terminated. On the other hand, when ΔP is equal to or less than ΔP _C , it is determined that both ASV 13 and RV 14 are in the closed state, and −1 indicating that the closed state is closed is set to the flag XFRV indicating the failure state of RV 14 ( Step S411) The process is terminated.

  When the subroutine of FIG. 12 is completed, the process proceeds to step S41 shown in FIG. 11, and the value of the flag XAI is checked. If the value is -1, a failure of the device has been detected, so the process proceeds to step S57 to be described later, and the value is not -1 (precisely, since the abnormality detection process has not ended, the initial value is 0). If yes, the process proceeds to step S43, the air pump 12 is operated, the ASV 13 is opened, and the AI supply is started. In subsequent step S44, it is checked whether or not an abnormality detection condition is satisfied. This abnormality detection condition is the same as the condition of step S8 in FIG. If the abnormality detection condition is not satisfied, the determination process is skipped and the process proceeds to step S50.

  If the abnormality detection condition is satisfied, the process proceeds to step S45, and the value of the flag XAI is checked. Only when XAI is 0, that is, when the abnormality detection process has not yet been performed, the process proceeds to step S46. When the determination result is normal, the determination process is skipped and the process proceeds to step S50. And migrate. In the case of an abnormality, this process is bypassed.

In step S46, the fluctuation of the pressure value P for a predetermined time is read. Then, the pressure average value Pm is calculated (step S47). In step S48, this Pm is compared with a threshold value P _D (higher than atmospheric pressure). If Pm is greater than P _D, it is determined that there is sufficient secondary air supply, and the process proceeds to step S49 where 1 indicating that the failure diagnosis flag XAI is normal is set. In step S50, it is checked whether or not the AI end condition is satisfied. If not, the process returns to step S44 to repeat the process and continue the secondary air supply. On the other hand, when the AI end condition is satisfied, the process proceeds to step S51 to stop the air pump 12, and closes the ASV 13 to stop the supply of secondary air and ends the process.

When Pm is determined to be less P _D in step S48, the proceeds to step S52, and compares the this Pm and P _A (which is a negative pressure lower than atmospheric pressure.). If Pm is less than P _A indicates ASV13 is in closed, a closed sticking state flag XFASV indicating a fault condition of the determination to ASV13 the secondary air supply is obstructed -1 Is set (step S53), and the process proceeds to step S55. On the other hand, if Pm is not less than P _A is, ASV 13 is located normally in the open state, as a result of the air pump 12 is stopped, it communicates with the air filter 25 side, as in the state nearly atmospheric pressure The flag XFAP indicating the failure state of the air pump 12 is set to -1 indicating that the air pump 12 is inoperative (step S54), and the process proceeds to step S55.

  In step S55, a value -1 indicating abnormality is set in the flag XAI indicating the system state. In step S56, the air pump 12 is stopped and the ASV 13 is closed. Actually, since any of the parts has failed, the secondary air supply cannot be performed originally, but this processing is performed to avoid inducing the failure of other normal equipment. Subsequently, in step S57, a warning process for notifying the driver that there is an abnormality in the system or failure detection has not been performed using a display device or an alarm (not shown) as in step S34 in FIG. To finish the process.

  According to this embodiment, it is possible to determine the abnormality of the RV 14 and the abnormality of some other devices before executing the AI. In addition, it is possible to determine the abnormality of other devices during the AI execution.

  Next, a third abnormality detection routine will be described with reference to FIGS. The secondary air supply apparatus in which this abnormality detection routine is implemented differs from the secondary air supply apparatus shown in FIG. 10 in that the air pump 12 is not provided as shown in FIG. FIG. 14 is a main flow of the abnormality detection process, and FIG. 15 is a flowchart showing a subroutine of the abnormality determination process for the reed valve.

  Since the processing content of the third abnormality detection routine is substantially the same as the processing content of the second abnormality detection routine, detailed description of the matching parts is omitted. After the AI execution condition establishment determination (step S39) and the AI device abnormality determination (step S40), the routine proceeds to a reed valve abnormality determination process (step S40a). FIG. 15 is a flowchart showing the abnormality determination process. This abnormality determination process excludes only steps S408 and S409 related to the air pump 12 in the abnormality determination process flow shown in FIG. Therefore, detailed description of the content is omitted.

  When the subroutine of FIG. 15 is completed, the process proceeds to step S41 shown in FIG. 14, and after checking the flag XAI (step S41), if the value is not −1, the ASV 13 is opened and the AI is opened. Supply is started (step S43a). Subsequently, the establishment of the abnormality detection condition is confirmed (step S44), and if not satisfied, the determination process is skipped and the process proceeds to step S50.

  If the abnormality detection condition is satisfied, the flag XAI is checked (step S45), and only when XAI is 0, the process proceeds to step S46. In other cases, the determination process is skipped and step S50 is performed. Migrate to

  In step S46, the fluctuation of the pressure value P for a predetermined time is read. Then, the pressure average value Pm is calculated (step S47). In step S48a, it is confirmed whether this Pm is near atmospheric pressure (in the case of relative pressure, near 0). If it is near atmospheric pressure, it is determined that there is sufficient secondary air supply, and the process proceeds to step S49 where 1 is set in the failure diagnosis flag XAI indicating normality. In step S50, it is checked whether or not the AI end condition is satisfied. If not, the process returns to step S44 to repeat the process and continue the secondary air supply. On the other hand, when the AI end condition is satisfied, the process proceeds to step S51a, the ASV 13 is closed, the secondary air supply is stopped, and the process is ended.

  If Pm is not near atmospheric pressure in step S48a, specifically, if the negative pressure is high, it is determined that the ASV 13 is in a closed state and the secondary air supply is blocked, and the process proceeds to step S55a. A flag XFASV indicating a failure state of the ASV 13 is set to -1 indicating a closed fixed state, and a flag XAI indicating a system state is set to -1. (Step S53). In step S56a, control for closing the ASV 13 is performed. In practice, the ASV 13 is in a closed stuck state, but this process is performed to avoid inducing other normal equipment failures. The subsequent processing in step S57 is the same as that in FIG.

  The abnormality detection process routine can also accurately determine the abnormality mode of the component device as in the second abnormality detection process routine.

  Next, a fourth abnormality detection processing routine will be described with reference to FIGS. This abnormality detection processing routine is executed in the secondary air supply apparatus shown in FIG. Then, the discharge amount reduction of the air pump 12 and the fuel system abnormality are determined, and can be used together with the first abnormality detection processing routine shown in FIGS.

  FIG. 16 shows the main flow of this processing routine. First, in step S60, it is checked whether or not AI control is being performed. If the AI control is not in progress, the subsequent processing is skipped and the processing is terminated. On the other hand, when the AI control is being performed, the process proceeds to step S62.

Next, the fluctuation of the discharge pressure P of the air pump 12 for a predetermined time, actually the measured value of the pressure sensor 15 is read (step S62), and the pressure average value Pm is calculated (step S64). Then compared with the Pm and the threshold P _F (step S66). If Pm is less than P _F, since it means that the ejection amount is insufficient (see FIG. 8), together with sets 1 in the flag Xfaildown representing the flow reduction of the air pump operation proceeds to step S67, the system The flag XAI indicating the state of -1 is set to -1 indicating the failure state, and the process is terminated.

On the other hand, if Pm is larger than P _F , the process proceeds to step S68, where Pm is compared with the threshold value P _G (where P _F <P _G ). If Pm is greater than P _G is the air pump 12 is normal, it is determined that the discharge pressure since the piping is clogged is increased, the flag Xjam representing the piping clogging proceeds to step S69 1 Is set, and -1 indicating a failure state is set in the flag XAI indicating the system state, and the process is terminated.

On the other hand, Pm is the case less than P _G, the process proceeds to A / F sensor activation determining processing in step S70. Here, the A / F sensor refers to a sensor that can detect the air-fuel ratio, excess air ratio, etc. of the exhaust gas including the O ₂ sensor 31 shown in FIG.

  FIG. 17 is a flowchart of specific processing of the A / F sensor activation determination processing. First, in step S700, it is checked whether AI control is being performed. If it is not under control, the process is skipped and the process ends. In step S702, the value of the flag XAF indicating the activated state is checked. The value of the flag XAF is 0 when the activation determination has not been completed, and -1 when the sensor is abnormal, and 1 when the activation has been completed. If XAF is other than 0 in step S702, the subsequent process is skipped and the process ends.

In subsequent steps S704 and S706, the elapsed time Δt _st after engine start is compared with predetermined threshold values Δt _th1 and Δt _th2 (where Δt _th1 <Δt _th2 ). If Δt _st is equal to or _smaller than Δt _th1 , the rotation of the engine 2 may not be stable, so the process returns to step S700 and the process is repeated. If Δt _st is equal to or greater than Δt _th2 , it indicates that the A / F sensor has not been activated even after Δt _{th2 has} elapsed, so it is determined that the A / F sensor is abnormal, and the process proceeds to step S707 to flag Set XAF to -1 to end the process. In other cases, that is, when Δt _st exceeds Δt _th1 and is smaller than Δt _th2 , the process proceeds to step S708, and the time change amount Δθ of the throttle opening is fetched from the engine ECU 23 and compared with the threshold value Δθth. If Δθ is greater than or equal to Δθth, the engine 2 is in a transient state and the activation determination described below cannot be performed accurately, so the process returns to step S700 and the process is repeated again.

If it is determined in step S708 that the engine is smaller than Δθth, then the air pump 12 is stopped, the ASV 13 is closed, AI is temporarily stopped (step S710), and the output value of the O ₂ sensor 31 is detected. From A, the difference Δλ between the A / F before and after the stop is calculated (step S712). In the subsequent step S714, this Δλ is compared with the threshold value Δλth. If there is a significant difference between the AI supply and the stop, it can be considered that the A / F sensor is activated. Therefore, the process proceeds to step S716, where the flag XAF is set to 1, and the process is terminated. On the other hand, if no significant difference is found, the process ends without changing the flag XAF because it is not activated yet.

  After completion of the determination process shown in FIG. 17, the process returns to step S72 shown in FIG. 16, and the value of the flag XAF is checked. When this value is 0, it returns to step S70 (it is preferable to provide a fixed waiting time), and re-determination is performed. When the value is −1, the following process determination using the A / F sensor cannot be performed, so that the subsequent process is skipped and the process ends. Only when the value is 1, the process proceeds to step S74.

In step S74, the exhaust secondary A / F value λ ₂ at the time of AI is read from the output of the O ₂ sensor 31, and subsequently, the target secondary A / F calculated from the intake air amount Ga measured by the air flow meter 26. The value λ _2t is calculated (step S76). There is a relationship shown in FIG. 18A between Ga and λ _2t . In step S78, λ ₂ and λ _2t are compared. If λ ₂ is equal to or greater than λ _2t , it is determined that sufficient secondary air is being supplied, and the process proceeds to step S80 where 1 is set in the flag XAI indicating the system status to indicate normality. Exit.

On the other hand, when λ ₂ is less than λ _2t , it indicates that the supply amount of secondary air is insufficient. Therefore, first, the air pump 12 is stopped and the ASV 13 is closed to stop the secondary air supply (step S82), and the output of the O ₂ sensor 31 at this time, that is, the exhaust gas when the secondary air supply is stopped is stopped. An A / F value (hereinafter referred to as a primary A / F value) λ ₁ is read (step S84). Subsequently, the difference between λ ₂ and λ ₁ is set to Δλ (step S86), and a target A / F fluctuation value Δ (A / F) = Δλ _th calculated from the intake air amount Ga measured by the air flow meter 26 is set. Calculate (step S88). There is a relationship shown in FIG. 18B between Ga and λ _2t . Subsequently, Δλ and Δλ _th are compared (step S90). When Δλ is equal to or smaller than Δλ _th , it is determined that the discharge amount itself is actually insufficient, but the discharge pressure itself has increased due to clogging, and the process proceeds to step S91, where flags Xjam, Xfaildown 1 is set to X, and -1 is set to XAI, and the process is terminated.

On the other hand, if Δλ exceeds Δλ _th , it is determined that the air-fuel ratio is abnormally rich, a fuel system abnormality determination is performed (step S92), and then the processing ends. The specific contents of the fuel system abnormality determination process will be omitted.

  According to this process, it is possible to accurately determine a decrease in the flow rate of the air pump 12 or a clogging of the pipe 11.

  Next, a fifth abnormality detection processing routine will be described with reference to FIGS. This abnormality detection processing routine is executed in the secondary air supply apparatus shown in FIG.

  FIG. 19 is a main flow of this process. First, in step S61, it is checked whether or not AI control is being performed. If the AI control is not in progress, the subsequent processing is skipped and the processing is terminated. On the other hand, when the AI control is being performed, the process proceeds to step S63, and it is checked whether or not the engine is in the first idle state after start-up (whether it is first idle).

  Next, the process proceeds to A / F sensor activation determination processing in step S70. The content of this activation determination process is the process shown in FIG. After the processing, the process proceeds to step S71, and the value of the flag XAF is checked. When this value is 0, it returns to step S70 (it is preferable to provide a fixed waiting time), and re-determination is performed. When the value is −1, the following process determination using the A / F sensor cannot be performed, so that the subsequent process is skipped and the process ends. Only when the value is 1, the process proceeds to step S71.

In step S71, the coolant temperature _THW data is received from the engine ECU 23, and the normal engine speed NE1 is calculated based on the relationship shown in FIG. Then, to calculate the Δλw a A / F value is expected to increase by a secondary air supply from the T _HW based on the relationships shown in FIG. 20 (b) (step S75). In step S77, the actual engine speed NE is compared with NE1.

If NE is greater than NE1, the process proceeds to step S79, calculates the λw the expected A / F value in the absence of the secondary air supplied from the T _HW based on the relationships shown in FIG. 20 (c) . Next, the exhaust secondary A / F value λ ₂ at the time of secondary air supply is read from the output of the O ₂ sensor 31 (step S81), and the difference between λ ₂ and λw is set to Δλ (step S83). Then, Δλ and Δλw are compared (step S85).

  If Δλ is larger than Δλw, it is determined that there is sufficient secondary air supply, the secondary air supply device is determined to be normal, the process proceeds to step S87, 1 is set in the flag XAI, and the process is terminated.

On the other hand, if NE is equal to or less than NE1 in step S77, and if Δλ is equal to or less than Δλw in step S85, the process proceeds to step S89, the air pump 12 is stopped, the ASV 13 is closed, and the secondary Stop air supply. Next, the exhaust primary A / F value λ ₁ when the secondary air is stopped is read from the output of the O ₂ sensor 31 (step S93), and the difference between λ ₂ and λ ₁ is set to Δλ (step S95). Then, Δλ and Δλw are compared (step S97).

  If Δλ is larger than Δλw, it is determined that there is sufficient secondary air supply, the secondary air supply device is determined to be normal, the process proceeds to step S87, 1 is set in the flag XAI, and the process is terminated.

  On the other hand, if Δλ is smaller than Δλw, it is determined that the secondary air supply device is abnormal because the secondary air supply is not sufficient, the process proceeds to step S99, and the flag XAI is set to −1 and the process is terminated. .

  In this abnormality detection processing routine, when it is determined to be normal using the predicted A / F, that is, when the combustion state is good immediately after start-up, the determination processing by forcibly turning off the secondary air supply device is not performed. A decrease in emission can be suppressed, which is preferable.

  The present invention is not limited to the use of abnormality abnormality detection processing routines, and all changes, modifications, and improvements of routines that have the same combination and basic concept are included in the present invention.

DESCRIPTION OF SYMBOLS 1 ... Secondary air supply apparatus, 2 ... Engine, 10 ... Control apparatus, 11 ... Secondary air supply passage, 12 ... Air pump, 13 ... ASV (air switching valve), 14 ... Reed valve (check valve), 15 ... pressure sensor, 16 ... pipe, 17 ... electromagnetic valve, 20 ... intake pipe, 21 ... exhaust pipe, 22 ... exhaust gas purifying apparatus, 23 ... engine ECU, 24 ... throttle, 25 ... intake air filter, 31 and 32 ... O ₂ sensor.

Claims (13)

A secondary air supply passage for supplying secondary air upstream from an exhaust purification device of an exhaust system of an internal combustion engine, an opening / closing means for opening / closing the secondary air supply passage, and a check arranged downstream of the opening / closing means A secondary air supply device comprising a valve,
A pressure sensor disposed on the secondary air supply passage; and an abnormality detection unit that detects an abnormality of the component based on a time average value of pressure values detected by the pressure sensor and a pressure fluctuation value. Secondary air supply device. The secondary air supply apparatus according to claim 1, wherein the abnormality detection unit detects a failure mode of each component from a combination of pressure behavior patterns during secondary air supply control and supply stop control. The secondary air supply device according to claim 2, wherein an air pump is disposed upstream of the opening / closing means, and the pressure sensor is disposed at an intermediate position between the air pump and the opening / closing means. 4. The secondary air supply apparatus according to claim 3, wherein the pressure sensor is an absolute pressure sensor, and the abnormality detection unit stores a detected value immediately before starting the engine of the pressure sensor as an atmospheric pressure. 5. The secondary air supply device according to claim 3, wherein the abnormality detection unit further has a function of monitoring a flow rate of the air pump from an output value of the pressure sensor. The abnormality detection unit detects clogging of the secondary air supply passage by driving the air pump and detecting discharge pressure of the air pump at the time of opening / closing control of the opening / closing means. Item 6. The secondary air supply device according to any one of Items 3 to 5. The secondary air supply device according to any one of claims 1 to 6, further comprising an air-fuel ratio sensor disposed in the exhaust system, wherein the output is further input to the abnormality detection unit. 8. The secondary air supply device according to claim 7, wherein the abnormality detection unit makes an abnormality determination based on a difference between a target air-fuel ratio and an actual air-fuel ratio corresponding to an intake air amount. 8. The secondary air supply device according to claim 7, wherein the abnormality detection unit makes an abnormality determination based on a difference between an expected air-fuel ratio and an actual air-fuel ratio corresponding to an engine coolant temperature. The secondary air supply device according to any one of claims 7 to 9, wherein the abnormality detection unit performs an abnormality determination based on a difference in air-fuel ratio between the secondary air supply control and the stop control. The secondary air supply device according to any one of claims 7 to 10, wherein the abnormality detection unit determines activation of the air-fuel ratio sensor by forcibly turning off secondary air supply control temporarily. The secondary air supply device according to claim 1, wherein the pressure sensor is disposed between the opening / closing means and the check valve. The secondary air supply according to claim 12, wherein the abnormality detection unit detects an abnormality of the check valve based on a pressure value and a pressure fluctuation value detected by the pressure sensor when the opening / closing means is in a closed control state. apparatus.

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