JP2011226415A - Abnormality determination device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable abnormality determination of a diaphragm while preventing effects etc. from other actuators, in an abnormality determination device for an internal combustion engine.SOLUTION: The abnormality determination device for the internal combustion engine includes a waste gate valve 32 having the diaphragm 32b and first and second pressure chambers 32c, 32d partitioned by the diaphragm 32b. During idle operation in which intake pipe pressure (throttle downstream pressure) becomes negative pressure, solenoid valves 42, 44 are controlled so as to achieve a downstream communication state where the second pressure chamber 32d is communicated with a throttle downstream side portion. In the case where the solenoid valves 42, 44 are controlled so as to achieve the downstream communication state, when convergence time required until the intake pipe pressure converges is longer than a predetermined value, it is determined that the diaphragm 32b has an abnormality.

Description

  The present invention relates to an abnormality determination device for an internal combustion engine, and more particularly to an abnormality determination device for an internal combustion engine suitable for determining an abnormality of a wastegate valve provided in an internal combustion engine with a turbocharger.

  Conventionally, for example, Patent Document 1 discloses a decompressor that divides a decompression chamber and an atmospheric pressure chamber with a plate-like diaphragm and adjusts the gas pressure in the decompression chamber. This conventional pressure reducer includes a pressure sensor that detects the gas pressure in the pressure reduction chamber. Then, when the gas pressure in the decompression chamber decreases by this pressure sensor, it is determined that an abnormality has occurred in the decompressor.

JP 2002-371916 A JP-A-5-209532

  By the way, an internal combustion engine with a turbocharger having a wastegate valve is known. In order to determine the abnormality of the diaphragm provided inside the waste gate valve, it is necessary to use a determination method that is not easily affected by the actuator other than the waste gate valve, the temperature, or the like.

  The present invention has been made to solve the above-described problems, and provides an abnormality determination device for an internal combustion engine that is capable of determining an abnormality of a diaphragm while being hardly affected by other actuators. With the goal.

A first invention is an abnormality determination device for an internal combustion engine,
A turbocharger having a compressor disposed in the intake passage and a turbine disposed in the exhaust passage;
A wastegate valve having a diaphragm, and a first pressure chamber and a second pressure chamber defined by the diaphragm;
A first upstream flow path connecting a throttle upstream side portion between the compressor and the throttle valve in the intake passage and the first pressure chamber;
A second upstream flow path connecting the throttle upstream portion and the second pressure chamber;
A downstream flow path connecting the throttle downstream side portion of the intake passage downstream of the throttle valve and the second pressure chamber;
An upstream communication state in which the second pressure chamber communicates with the throttle upstream portion via the second upstream flow passage, and the second pressure chamber communicates with the throttle downstream portion via the downstream flow passage. Channel switching means for switching between the downstream communication state,
An intake pressure detecting means for detecting a throttle downstream pressure in the intake passage in the throttle downstream portion;
During the steady operation in which the throttle downstream pressure is negative due to the throttle passage being throttled by the throttle valve, the downstream communication state is established in which the second pressure chamber communicates with the throttle downstream portion. An abnormality determination start means for controlling the flow path switching means,
A convergence time measuring means for measuring a convergence time required for the throttle downstream pressure to converge when the flow path switching means is controlled so as to be in the downstream communication state by the abnormality determination start means;
An abnormality determining means for determining that an abnormality has occurred in the diaphragm when the convergence time is longer than a predetermined value;
It is characterized by providing.

The second invention is the first invention, wherein
The steady operation is an idle operation.

The third invention is the first or second invention, wherein
Pressure chamber pressure detecting means for detecting the pressure in the second pressure chamber;
A pressure for determining whether or not the pressure in the second pressure chamber is higher than the throttle downstream pressure by a predetermined value or more after the flow path switching unit is controlled so as to be in the downstream communication state by the abnormality determination start unit. A comparison means,
The abnormality determining means determines that an abnormality has occurred in the diaphragm when the pressure in the second pressure chamber is higher than the predetermined value by the predetermined pressure.

  According to the first aspect of the present invention, the flow path switching means is controlled so as to be in the downstream communication state during steady operation in which the throttle downstream pressure is negative due to the throttle passage being throttled. Thus, the second pressure chamber is controlled to a negative pressure. Then, in a situation in which the second negative pressure chamber is controlled to a negative pressure, it is determined that an abnormality has occurred in the diaphragm when the convergence time required for the throttle downstream pressure to converge is longer than a predetermined value. As a result, it is possible to make an abnormality determination that is less susceptible to the influence of other actuators provided in the internal combustion engine, the temperature, and the like. For this reason, it is possible to accurately determine the abnormality of the diaphragm.

  According to the second aspect of the present invention, it is possible to ensure a sufficient opportunity for executing the abnormality determination by performing the abnormality determination during idling with a high operation frequency.

  Even when there is an abnormality in the diaphragm, the convergence time of the throttle downstream pressure may be in a period equivalent to that in the normal state. However, even if the convergence time is equal to that at the normal time, a difference is generated between the pressure in the second pressure chamber and the throttle downstream pressure at the time of abnormality. According to the third aspect of the invention, even when the convergence time of the throttle downstream pressure is equal to the normal time, it is possible to make a more accurate abnormality determination.

It is a figure for demonstrating the structure of the internal combustion engine of Embodiment 1 of this invention. It is a figure for demonstrating the specific structure of the wastegate valve | bulb shown in FIG. 1, and its periphery. It is a time chart for demonstrating the abnormality determination method of the diaphragm in Embodiment 1 of this invention. It is a flowchart of the routine performed in Embodiment 1 of the present invention. It is a flowchart of the routine performed in Embodiment 2 of this invention.

Embodiment 1 FIG.
[System Configuration of Embodiment 1]
FIG. 1 is a diagram for explaining a configuration of an internal combustion engine 10 according to a first embodiment of the present invention. As shown in FIG. 1, an intake passage 12 and an exhaust passage 14 communicate with the internal combustion engine 10. An air cleaner 16 is attached to the inlet of the intake passage 12. An air flow meter 18 that outputs a signal corresponding to the flow rate of air taken into the intake passage 12 is provided in the vicinity of the downstream side of the air cleaner 16.

  A compressor 20 a of the turbocharger 20 is disposed downstream of the air flow meter 18 in the intake passage 12. An intercooler 22 for cooling the compressed air is provided downstream of the compressor 20a. A throttle valve 24 is disposed downstream of the intercooler 22. The throttle valve 24 is an electronically controlled valve that is driven by a throttle motor (not shown) based on the accelerator opening. A throttle position sensor 26 for detecting the throttle opening is provided in the vicinity of the throttle valve 24.

  The intake passage 12 includes an intake manifold 12a for distributing intake air to each cylinder on the downstream side of the throttle valve 24. The intake manifold 12a is provided with an intake pressure sensor 28 for detecting the internal pressure (referred to as “intake pipe pressure” or “throttle downstream pressure” in this specification).

  A turbine 20 b of the turbocharger 20 is disposed in the exhaust passage 14. The exhaust passage 14 is provided with an exhaust bypass passage 30 that bypasses the turbine 20b. The exhaust bypass passage 30 is provided with a waste gate valve 32 that opens and closes the exhaust bypass passage 30.

FIG. 2 is a view for explaining a specific configuration of the wastegate valve 32 and its periphery shown in FIG.
The waste gate valve 32 shown in FIG. 2 is a two-chamber waste gate valve. The wastegate valve 32 includes a diaphragm (rubber film) 32b to which a valve body 32a for opening and closing the exhaust bypass passage 30 is fixed. Inside the waste gate valve 32, a first pressure chamber 32c and a second pressure chamber 32d defined by a diaphragm 32b are formed. In addition, a spring 32e that urges the diaphragm 32b toward the first pressure chamber 32c is provided inside the second pressure chamber 32d.

  Here, a portion of the intake passage 12 between the compressor 20a and the throttle valve 24 is hereinafter referred to as a “throttle upstream portion”. The upstream portion of the throttle and the first pressure chamber 32 c are connected by a first air pipe 34. One end of the second air pipe 36 is connected to the upstream portion of the throttle. In addition, one end of a third air pipe 38 is connected to a portion of the intake passage 12 on the downstream side of the throttle valve 24 (hereinafter referred to as “throttle downstream portion”). The second air pipe 36 and the third air pipe 38 merge at the other end of the fourth air pipe 40 whose one end is connected to the second pressure chamber 32d.

  A first solenoid valve (actuator) 42 that opens and closes the second air pipe 36 is installed in the middle of the second air pipe 36, and the third air pipe 38 is installed in the middle of the third air pipe 38. The 2nd solenoid valve (actuator) 44 which bears opening and closing of is installed. According to such a configuration, when the first electromagnetic valve 42 is opened and the second electromagnetic valve 44 is closed, the intake passage 12 is connected via the second air pipe 36 and the fourth air pipe 40. The upstream portion of the throttle and the second pressure chamber 32d communicate with each other (hereinafter referred to as “upstream communication state”). Conversely, when the first solenoid valve 42 is closed and the second solenoid valve 44 is opened, the throttle downstream side portion of the intake passage 12 is connected to the intake passage 12 via the third air pipe 38 and the fourth air pipe 40. The second pressure chamber 32d communicates (hereinafter referred to as “downstream communication state”). Further, a pressure sensor 46 for detecting the internal pressure is incorporated in the second pressure chamber 32d.

  According to the above configuration, the upstream communication state and the downstream communication state can be switched by controlling the opening and closing of the first electromagnetic valve 42 and the second electromagnetic valve 44. When the upstream communication state is selected, atmospheric pressure or higher pressure similarly acts on both the first pressure chamber 32c and the second pressure chamber 32d. In this case, since no pressure difference is generated between the first pressure chamber 32c and the second pressure chamber 32d, the waste gate valve 32 is closed by the urging force of the spring 32e. Further, when the downstream communication state is selected under the condition that the intake manifold 12a is at a negative pressure because the intake passage 12 is throttled by the throttle valve 24, the second pressure chamber 32d also has a negative pressure. Become. That is, in this case, the second pressure chamber 32d functions as a negative pressure chamber. It should be noted that the pressure in the second pressure chamber 32d can be adjusted by adjusting the opening degree of the first electromagnetic valve 42 and the second electromagnetic valve 44 to an arbitrary opening degree, whereby the first pressure chamber 32c. The pressure difference between the inside and the second pressure chamber 32d can be adjusted. When the pressure difference is set to a value that overcomes the urging force of the spring 32e, the valve body 32a opens. That is, the opening degree of the waste gate valve 32 can be adjusted to an arbitrary opening degree by adjusting the opening degree of the first electromagnetic valve 42 and the second electromagnetic valve 44 to an arbitrary opening degree.

  Further, the system shown in FIG. 1 includes an ECU (Electronic Control Unit) 50. In addition to the intake pressure sensor 28 and the pressure sensor 46 described above, various sensors such as a crank angle sensor 52 for detecting the engine speed and an accelerator opening sensor 54 for detecting the accelerator opening are connected to the ECU 50. In addition, various actuators such as the first electromagnetic valve 42 and the second electromagnetic valve 44 described above are connected.

[Diaphragm Abnormality Determination Method in Embodiment 1]
The abnormality determination method for the diaphragm 32b in this embodiment is to determine whether or not there is a gas leak from the first pressure chamber 32c to the second pressure chamber 32d due to the occurrence of a hole or a crack in the diaphragm 32b. Specifically, in the present embodiment, when the internal combustion engine 10 is in an idling state, the first electromagnetic valve 42 and the second electromagnetic valve 44 are controlled in order to control the second pressure chamber 32d to have a negative pressure. Control to form a downstream communication state. In this case, when the convergence time required for the intake pipe pressure (throttle downstream pressure) to converge to the value before the formation of the downstream communication state is longer than a predetermined value, the gas leakage (abnormality of the diaphragm 32b) ) Has occurred.

Hereinafter, the abnormality determination method will be described in detail with reference to FIG.
FIG. 3 is a time chart for explaining an abnormality determination method for the diaphragm 32b in the first embodiment of the present invention. More specifically, FIG. 3A shows a waveform representing a change in diaphragm pressure (pressure in the second pressure chamber 32d that can be on the negative pressure side), and FIG. 3B shows the intake pipe pressure (throttle downstream pressure). 3 (C) shows a waveform indicating success or failure of the idle flag, FIG. 3 (D) shows a waveform showing success or failure of the abnormal leakage determination control execution flag of the diaphragm 32b, and FIG. 3 (F) shows a waveform representing the opening of the second electromagnetic valve 44, and FIG. 3 (G) shows a waveform representing a change in the throttle opening. ing.

  The time chart shown in FIG. 3 shows an idle flag indicating that the internal combustion engine 10 is idling at time t0 when the throttle valve 24 is fully closed, as shown in FIGS. 3 (C) and 3 (G). Shows an example in which is set to ON. When the idle flag is turned ON, the first electromagnetic valve 42 is opened and the second electromagnetic valve 44 is closed as shown in FIGS. 3E and 3F to close the wastegate valve 32. . Further, when the solenoid valves 42 and 44 are controlled in this way, an upstream communication state is formed, so that the pressures in the first pressure chamber 32c and the second pressure chamber 32d are the same value (because the idling time is large). Pressure).

  As described above, the abnormality determination (leakage determination) of the present embodiment is started under the situation where the upstream communication state is formed at the time of idling. Specifically, in order to enter the downstream communication state, as shown in FIGS. 3E and 3F, the first electromagnetic valve 42 is closed and the second electromagnetic valve 44 is opened. Further, during execution of this abnormality determination, the leakage determination control execution flag is turned ON as shown in FIG.

Here, the following equation (1) indicates the Wheelshall's law. The following equation (2) is an equation relating to the gas flow rate M flowing into and out of the intake manifold 12a.
dP · V = dM · R · T (1)
dM = M _in + M _WGV −M _out (2)
In the above formula (1), P is the intake pipe pressure (throttle downstream pressure), V is the intake manifold volume, R is the gas constant, and T is the gas temperature in the intake manifold 12a. In the above _{(2), M in} is a gas flow rate flowing into the intake manifold 12a through the intake passage 12 on the upstream _{side, M WGV} the gas flow entering the intake manifold 12a from the second pressure chamber 32d Yes, M _out is the flow rate of gas flowing _out of the intake manifold 12a.

(1), according to (2) the relationship is the throttle opening as during idling is constant, and the condition is M _out and M _in a constant gas flow rate from the second pressure chamber 32d As _MWV increases, the intake pipe pressure P increases.

  In the idling state where the throttle valve 24 is closed, the intake pipe pressure (throttle downstream pressure) is negative. Accordingly, when the state is switched from the upstream communication state to the downstream communication state at the time of idling at time t1, the second pressure chamber 32d in the atmospheric pressure state communicates with the intake manifold 12a in the negative pressure state. As a result, a gas flow from the second pressure chamber 32d toward the intake manifold 12a occurs, so that the diaphragm pressure decreases as shown in FIG. 3 (A), and as shown in FIG. 3 (B), The intake pipe pressure P increases.

Here, first, the case where the diaphragm 32b is normal will be described.
If the diaphragm 32b is normal, the gas in the second pressure chamber 32d is exhausted into the intake manifold 12a, and then the diaphragm pressure and the intake air as shown by the solid line in FIGS. 3 (A) and 3 (B). The pipe pressure is the same value. Thereafter, at time t2, the intake pipe pressure P converges to a value before the start of leakage determination control (ie, time t1). That is, when a gas flow from the second pressure chamber 32d toward the intake manifold 12a occurs, and the diaphragm 32b is normal, the gas flow rate _MWV is consumed by the intake manifold 12a. Eventually it becomes zero. Therefore, if the diaphragm 32b is normal, the intake pipe pressure P increases with a temporary increase in the gas flow rate M _WGV , but the gas flow rate M _out increases with the increase in the intake pipe pressure P. As a result, the intake pipe pressure P decreases as shown in FIG.

On the other hand, if an abnormality such as a hole or a crack is generated in the diaphragm 32b, the first pressure chamber 32c and the second pressure chamber 32d communicate with each other when the downstream communication state is formed at the time t1, so that the gas flow rate M _out gas will continue to flow. As a result, as shown by a broken line in FIG. 3A, the diaphragm pressure is less likely to be lower than that at normal time. For this reason, as indicated by a broken line in FIG. 3B, the convergence time (t2-t1) required until the intake pipe pressure P converges is longer than that in the normal state.

  Therefore, in this embodiment, as described above, when the convergence time (t2-t1) required for the intake pipe pressure (throttle downstream pressure) to converge to the value before the start of the leak determination is longer than a predetermined value. The gas leakage (abnormality of the diaphragm 32b) is determined to occur.

FIG. 4 is a flowchart of a routine executed by the ECU 50 in the first embodiment to realize the above function.
In the routine shown in FIG. 4, first, based on the output of the accelerator opening sensor 54 or the like, it is determined whether or not the operating state of the internal combustion engine 10 is an idle state (step 100). As a result, when it is determined that the engine is not in the idle state, the leakage determination control execution flag is turned off (step 102).

  On the other hand, if it is determined in step 100 that the engine is in the idle state, it is determined whether a predetermined leakage determination execution condition is satisfied (step 104). As a result, when it is determined that the leak determination execution condition is not satisfied, the first electromagnetic valve 42 is fully opened and the second electromagnetic valve 44 is fully closed (step 106).

  On the other hand, when it is determined in step 104 that the leakage determination execution condition is satisfied, it is determined whether or not the leakage determination control is not executed based on whether or not the leakage determination control execution flag is satisfied (step 108). . As a result, when the determination of this step 108 is established, that is, when the leakage determination control execution flag is OFF, the current intake pipe pressure (negative pressure) P is measured using the intake pressure sensor 28, and The measured value is recorded as the convergence value of the intake pipe pressure P when the leakage determination is executed in this routine (step 110).

  Next, in order to bring the second pressure chamber 32d into a negative pressure state, the first electromagnetic valve 42 is fully closed and the second electromagnetic valve 44 is fully opened (step 112). Next, the time t1 when the electromagnetic valves 42 and 44 are controlled in this way is recorded (step 114). Next, the leakage determination control execution flag is turned ON (step 116).

  On the other hand, when it is determined that step 108 is not established, that is, when the leak determination control execution flag is ON, the intake pipe pressure P is measured using the intake pressure sensor 28 (step 118). Next, it is determined whether or not the intake pipe pressure P measured in step 118 has converged to the convergence value recorded in step 110 (step 120).

  As a result, if it is determined that the intake pipe pressure P has not yet converged to the convergence value, the leakage determination control execution flag remains ON (step 122). On the other hand, when it is determined in step 120 that the intake pipe pressure P has converged to the convergence value, the time t2 at the time of convergence is recorded (step 124). Next, the leakage determination control execution flag is turned off (step 126).

  Next, the difference between the time t2 recorded in the step 124 and the time t1 recorded in the step 114, that is, the convergence time (t2-t1) required for the convergence of the intake pipe pressure P this time is a predetermined value ( For example, it is determined whether it is longer than 1 second (step 128). As a result, when the determination in step 128 is established, it is determined that an abnormality has occurred in the diaphragm 32b (that is, a gas leak has occurred) (step 130). On the other hand, when the determination in step 128 is not established, it is determined that the diaphragm 32b is normal (that is, there is no gas leakage) (step 132).

According to the routine shown in FIG. 4 described above, in the idling state, control is performed so that the inside of the second pressure chamber 32d communicates with the throttle downstream side portion of the intake passage 12 under a negative pressure condition, and then this control is started. The abnormality determination of the diaphragm 32b is executed according to the convergence time (t2-t1) required until the intake pipe pressure P converges to the previous value. That is, in the steady idle state, the pressure in the second pressure chamber 32d is changed to the negative pressure state using the electromagnetic valves 42 and 44, and the convergence time of the intake pipe pressure (throttle downstream pressure) is used. An abnormality is determined. According to such a method, it is possible to perform abnormality determination that is not easily influenced by other actuators provided in the internal combustion engine 10 or temperature. For this reason, it is possible to accurately determine the abnormality of the diaphragm 32b.

  Moreover, when performing abnormality determination of the diaphragm 32b provided in the wastegate valve 32, it is preferable that a sufficient opportunity for performing abnormality determination is ensured. In the present embodiment, by performing abnormality determination in an idling state with high driving frequency, it is possible to sufficiently ensure an opportunity for executing abnormality determination.

  In the first embodiment described above, the first air pipe 34 is the “first upstream flow path” in the first invention, and the second air pipe 36 and the fourth air pipe 40 are the first invention. In the “second upstream flow path”, the third air pipe 38 and the fourth air pipe 40 are in the “downstream flow path” in the first invention, and the first electromagnetic valve 42 and the second electromagnetic valve 44 are in the above-described manner. It corresponds to the “channel switching means” in the first invention. Further, when the ECU 50 executes the processing of step 110 or 118, the “intake pressure detecting means” in the first invention executes the processing of step 112, thereby executing the “abnormality determination” in the first invention. When the “starting means” executes the processes of steps 114 and 124, the “convergence time measuring means” in the first invention executes the processes of steps 128, 130, and 132. The “abnormality determination means” in FIG.

Embodiment 2. FIG.
Next, a second embodiment of the present invention will be described with reference to FIG.
The system of the present embodiment can be realized by causing the ECU 50 to execute a routine shown in FIG. 5 described later instead of the routine shown in FIG. 4 using the hardware configuration shown in FIG.

  In the first embodiment described above, in a steady idling state, control is performed so that the second pressure chamber 32d communicates with the throttle downstream side portion of the intake passage 12 under a negative pressure condition, and then this control is started. The abnormality determination of the diaphragm 32b is performed according to the convergence time (t2-t1) required for the intake pipe pressure to converge to the previous value. On the other hand, in the present embodiment, in the steady idling state, the second pressure chamber 32d is similarly controlled to communicate with the throttle downstream side portion of the intake passage 12 under a negative pressure condition. When the pressure (diaphragm pressure) in the second pressure chamber 32d is higher than the intake pipe pressure (throttle downstream pressure) by a predetermined value or more, it is determined that an abnormality has occurred in the diaphragm 32b.

  FIG. 5 is a flowchart of a routine executed by the ECU 50 in the second embodiment in order to realize the above function. In FIG. 5, the same steps as those shown in FIG. 4 in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted or simplified. In the routine shown in FIG. 5, steps 114 and 124 shown in FIG. 4 are deleted.

  In the routine shown in FIG. 5, if it is determined in step 120 that the intake pipe pressure P has converged to the convergence value, the diaphragm pressure (pressure in the second pressure chamber 32 d) is measured using the pressure sensor 46. (Step 200). Next, after the leakage determination control execution flag is turned off in step 126, the pressure in the second pressure chamber 32d measured in step 200 is higher than the intake pipe pressure P measured in step 118 by a predetermined value or more. It is determined whether or not (step 202).

  As a result, when the determination in this step 202 is established, it is determined that an abnormality has occurred in the diaphragm 32b (that is, a gas leak has occurred) (step 130). On the other hand, when the determination in this step 202 is not established, it is determined that the diaphragm 32b is normal (that is, there is no gas leakage) (step 132).

  As shown in FIGS. 3A and 3B, when the diaphragm 32b is abnormal, the diaphragm pressure and the intake pipe pressure are not the same value, and the diaphragm pressure is higher than the intake pressure. Become. According to the routine shown in FIG. 5 described above, when the second pressure chamber 32d is controlled to communicate with the throttle downstream side portion of the intake passage 12 in a negative pressure state in the idle state, When the pressure (diaphragm pressure) in the two pressure chambers 32d is higher than the intake pipe pressure (throttle downstream pressure) by a predetermined value or more, it is determined that an abnormality has occurred in the diaphragm 32b. That is, in the steady idle state, the electromagnetic valve 42, 44 is used to change the pressure in the second pressure chamber 32d to a negative pressure state, and then an abnormality is made using the difference between the diaphragm pressure and the intake pipe pressure. A determination is made. According to such a method, it is possible to perform abnormality determination that is not easily influenced by other actuators provided in the internal combustion engine 10 or temperature. For this reason, it is possible to accurately determine the abnormality of the diaphragm 32b.

  In the second embodiment described above, the abnormality determination method shown in FIG. 5 is performed instead of the abnormality determination method (see FIG. 4) in the first embodiment described above. Unlike such an embodiment, the abnormality determination in the following manner may be performed. That is, when it is determined that the convergence time (t2-t1) required for the convergence of the intake pipe pressure P is longer than a predetermined value using the routine method shown in FIG. 4, an abnormality occurs in the diaphragm 32b. It is determined that Further, when it is determined that the convergence time (t2-t1) required for the convergence of the intake pipe pressure P is equal to or less than the predetermined value, the process of step 202 of the routine shown in FIG. Then, it is determined whether or not the pressure (diaphragm pressure) in the second pressure chamber 32d is higher than the intake pipe pressure (throttle downstream pressure) by a predetermined value or more. If the determination in step 202 is true, even if it is determined that the convergence time (t2-t1) required for the convergence of the intake pipe pressure P is equal to or less than the predetermined value, the diaphragm 32b It is determined that an abnormality has occurred.

  Even when there is an abnormality in the diaphragm 32b, the convergence time of the intake pipe pressure may be the same as that during normal operation. However, even if the convergence time is equal to that in the normal state, a difference occurs between the diaphragm pressure and the intake pipe pressure in the abnormal case. Therefore, by using the abnormality determination method that combines the method of the first embodiment and the method of the second embodiment as described above, more accurate abnormality determination can be performed.

  In the modification of the second embodiment described above, the ECU 50 executes the same process as in step 200, so that the “pressure chamber pressure detection means” in the third invention is the same as in step 202. By executing the processing, the “pressure comparison means” in the third aspect of the present invention is realized.

  Incidentally, in the first and second embodiments described above, the abnormality determination of the diaphragm 32b is performed when the internal combustion engine 10 is idling. However, in the present invention, the abnormality determination is performed at the time of steady operation in which the throttle downstream pressure is negative due to the throttle passage being throttled by the throttle valve (that is, the flow path switching means is controlled and 2), it is not always necessary during idle operation.

10 internal combustion engine 12 intake passage 12a intake manifold 14 exhaust passage 20 turbocharger 20a compressor 20b turbine 24 throttle valve 28 intake pressure sensor 30 exhaust bypass passage 32 wastegate valve 32a valve body 32b diaphragm 32c first pressure chamber 32d second pressure Chamber 32e Spring 34 First air pipe 36 Second air pipe 38 Third air pipe 40 Fourth air pipe 42 First electromagnetic valve 44 Second electromagnetic valve 46 Pressure sensor 50 ECU (Electronic Control Unit)

Claims (3)

A turbocharger having a compressor disposed in the intake passage and a turbine disposed in the exhaust passage;
A wastegate valve having a diaphragm, and a first pressure chamber and a second pressure chamber defined by the diaphragm;
A first upstream flow path connecting a throttle upstream side portion between the compressor and the throttle valve in the intake passage and the first pressure chamber;
A second upstream flow path connecting the throttle upstream portion and the second pressure chamber;
A downstream flow path connecting the throttle downstream side portion of the intake passage downstream of the throttle valve and the second pressure chamber;
An upstream communication state in which the second pressure chamber communicates with the throttle upstream portion via the second upstream flow passage, and the second pressure chamber communicates with the throttle downstream portion via the downstream flow passage. Channel switching means for switching between the downstream communication state,
An intake pressure detecting means for detecting a throttle downstream pressure in the intake passage in the throttle downstream portion;
During the steady operation in which the throttle downstream pressure is negative due to the throttle passage being throttled by the throttle valve, the downstream communication state is established in which the second pressure chamber communicates with the throttle downstream portion. An abnormality determination start means for controlling the flow path switching means,
A convergence time measuring means for measuring a convergence time required for the throttle downstream pressure to converge when the flow path switching means is controlled so as to be in the downstream communication state by the abnormality determination start means;
An abnormality determining means for determining that an abnormality has occurred in the diaphragm when the convergence time is longer than a predetermined value;
An abnormality determination device for an internal combustion engine, comprising:   2. The abnormality determination device for an internal combustion engine according to claim 1, wherein the steady operation is an idle operation. Pressure chamber pressure detecting means for detecting the pressure in the second pressure chamber;
A pressure for determining whether or not the pressure in the second pressure chamber is higher than the throttle downstream pressure by a predetermined value or more after the flow path switching unit is controlled so as to be in the downstream communication state by the abnormality determination start unit. A comparison means,
3. The abnormality determination unit according to claim 1, wherein the abnormality determination unit determines that an abnormality has occurred in the diaphragm when the pressure in the second pressure chamber is higher than the predetermined pressure by the downstream pressure of the throttle. An abnormality determination device for an internal combustion engine.

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